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Yang, Shengying, Huibin Qin, Xiaolin Liang i Thomas Gulliver. "An Improved Unauthorized Unmanned Aerial Vehicle Detection Algorithm Using Radiofrequency-Based Statistical Fingerprint Analysis". Sensors 19, nr 2 (11.01.2019): 274. http://dx.doi.org/10.3390/s19020274.
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Unmanned aerial vehicles (UAVs) are now readily available worldwide and users can easily fly them remotely using smart controllers. This has created the problem of keeping unauthorized UAVs away from private or sensitive areas where they can be a personal or public threat. This paper proposes an improved radio frequency (RF)-based method to detect UAVs. The clutter (interference) is eliminated using a background filtering method. Then singular value decomposition (SVD) and average filtering are used to reduce the noise and improve the signal to noise ratio (SNR). Spectrum accumulation (SA) and statistical fingerprint analysis (SFA) are employed to provide two frequency estimates. These estimates are used to determine if a UAV is present in the detection environment. The data size is reduced using a region of interest (ROI), and this improves the system efficiency and improves azimuth estimation accuracy. Detection results are obtained using real UAV RF signals obtained experimentally which show that the proposed method is more effective than other well-known detection algorithms. The recognition rate with this method is close to 100% within a distance of 2.4 km and greater than 90% within a distance of 3 km. Further, multiple UAVs can be detected accurately using the proposed method.
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Ma, Qinghua, Lin Chen, Manyi Du, Yongan Zhang i Yaoxiang Zhang. "Localized and Moderate Phosphorus Application Improves Plant Growth and Phosphorus Accumulation in Rosa multiflora Thunb. ex Murr. via Efficient Root System Development". Forests 11, nr 5 (19.05.2020): 570. http://dx.doi.org/10.3390/f11050570.
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Roots have high plasticity with the ability to adapt to heterogeneous nutrient distribution, but little is known about the effects of phosphorus (P) supply methods and levels on Rosa multiflora Thunb. ex Murr. root growth and nutrient accumulation. A pot study was conducted with two P supply methods (mixed and localized application) and three levels (P-deficient, P-moderate and P-adequate). The results showed that with localized application, P-deficient and P-moderate treatments significantly improved total root length, total surface area, total length of fine roots, shoot DW and total P accumulation in Rosa multiflora compared with their respective mixed application at 45 days after being transplanted (DAT) and 92 DAT; for P-adequate supply, the same trends were observed at 45 DAT, but not at 92 DAT. At 92 DAT, with localized application, when P levels increased from P-deficient to P-moderate, total P accumulation increased by 43.3%; but when P levels increased from P-moderate to P-adequate, no effect was observed. Furthermore, higher P accumulation in leaves was observed in localized P-moderate condition; decreased P uptake per root dry weight and greater root/shoot ratio were observed in localized P-adequate at 92 DAT. Total P accumulation was positively correlated with total root length and root surface area (R2: 0.68~0.94). There was a significant interaction effect among treatment days, P supply methods and levels (p ≤ 0.05) on shoot DW, root DW, root/shoot ratio and total P accumulation. These findings indicated that localized and moderate P supply appear efficient for improving R. multiflora growth and P accumulation via efficient root system development.
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Chatterjee, Kaushik, C. S. Singh, A. K. Singh, Ashok Kr Singh i S. K. Singh. "Performance of wheat cultivars at varying fertility levels under system of wheat intensification and conventional method of wheat production system". Journal of Applied and Natural Science 8, nr 3 (1.09.2016): 1427–33. http://dx.doi.org/10.31018/jans.v8i3.977.
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A field experiment was conducted during rabi season of 2009-10 at Ranchi, Jharkhand to evaluate the performance of wheat cultivars at varying fertility levels under system of wheat intensification and conventional method of cultivation. The morpho-physiological analysis of growth and yield in wheat revealed that system of wheatintensification manifested higher total tillers m-2, leaf area index, dry matter accumulation, crop growth rate, number of spikes m-2, grains per spike and 1000-grain weight resulting in higher grain and straw yield over conventional method of cultivation. The net return and benefit: cost ratio as well as the nutrient uptake of nitrogen, phosphorus and potash was also recorded significantly higher under system of wheat intensification. Higher fertility level of 120 kg N ha-1, 60 kg P2O5 ha-1 and 40 kg K2O ha-1 also significantly improved the plant height, total tillers m-2, leaf area index, dry matter accumulation, crop growth rate, number of spikes m-2, grains per spike, 1000-grain weight, grain yield, straw yield, net return, benefit: cost ratio and nutrient uptake of nitrogen, phosphorus and potash. Among the wheat cultivars, K 9107 manifested significant improvement in growth attributes at all the growth stages resulting in significantly higher yield attributes, grain yield, straw yield, net return, benefit: cost ratio and nutrient uptake of nitrogen, phosphorus and potash than Birsa Gehu 3, HUW 468 and K 0307. Thus it can be concluded that the wheat variety K 9107 fertilized with 120 kg N ha-1, 60 kg P2O5 ha-1 and 40 kg K2O ha-1 under System of Wheat Intensification may able to boost up the wheat productivity under irrigated ecosystem of Chhotanagpur plateau region, India.
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He, Z. H., J. Parajka, F. Q. Tian i G. Blöschl. "Estimating degree day factors from MODIS for snowmelt runoff modeling". Hydrology and Earth System Sciences Discussions 11, nr 7 (25.07.2014): 8697–735. http://dx.doi.org/10.5194/hessd-11-8697-2014.
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Abstract. Degree-day factors are widely used to estimate snowmelt runoff in operational hydrological models. Usually, they are calibrated on observed runoff, and sometimes on satellite snow cover data. In this paper, we propose a new method for estimating the snowmelt degree-day factor (DDFS) directly from MODIS snow covered area (SCA) and ground based snow depth data without calibration. Subcatchment snow volume is estimated by combining SCA and snow depths. Snow density is estimated as the ratio of observed precipitation and changes in the snow volume for days with snow accumulation. Finally, DDFS values are estimated as the ratio of changes in the snow water equivalent and degree-day temperatures for days with snow melt. We compare simulations of basin runoff and snow cover patterns using spatially variable DDFS estimated from snow data with those using spatially uniform DDFS calibrated on runoff. The runoff performances using estimated DDFS are slightly improved, and the simulated snow cover patterns are significantly more plausible. The new method may help reduce some of the runoff model parameter uncertainty by reducing the total number of calibration parameters.
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He, Z. H., J. Parajka, F. Q. Tian i G. Blöschl. "Estimating degree-day factors from MODIS for snowmelt runoff modeling". Hydrology and Earth System Sciences 18, nr 12 (3.12.2014): 4773–89. http://dx.doi.org/10.5194/hess-18-4773-2014.
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Abstract. Degree-day factors are widely used to estimate snowmelt runoff in operational hydrological models. Usually, they are calibrated on observed runoff, and sometimes on satellite snow cover data. In this paper, we propose a new method for estimating the snowmelt degree-day factor (DDFS) directly from MODIS snow covered area (SCA) and ground-based snow depth data without calibration. Subcatchment snow volume is estimated by combining SCA and snow depths. Snow density is estimated to be the ratio between observed precipitation and changes in the snow volume for days with snow accumulation. Finally, DDFS values are estimated to be the ratio between changes in the snow water equivalent and difference between the daily temperature and the melt threshold value for days with snow melt. We compare simulations of basin runoff and snow cover patterns using spatially variable DDFS estimated from snow data with those using spatially uniform DDFS calibrated on runoff. The runoff performances using estimated DDFS are slightly improved, and the simulated snow cover patterns are significantly more plausible. The new method may help reduce some of the runoff model parameter uncertainty by reducing the total number of calibration parameters. This method is applied to the Lienz catchment in East Tyrol, Austria, which covers an area of 1198 km2. Approximately 70% of the basin is covered by snow in the early spring season.
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Zhu, Zijuan, Zengxiang Zhang, Lijun Zuo, Tianshi Pan, Xiaoli Zhao, Xiao Wang, Feifei Sun, Jinyong Xu i Ziyuan Liu. "Study on the Classification and Change Detection Methods of Drylands in Arid and Semi-Arid Regions". Remote Sensing 14, nr 5 (4.03.2022): 1256. http://dx.doi.org/10.3390/rs14051256.
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The aim of this study was to clarify the distribution of irrigated drylands in arid and semi-arid areas, where complex terrain, diverse crops and staggered cultivated lands exist. This paper studied the classification methods of irrigated drylands based on temperature, precipitation, Normalized Difference Vegetation Index (NDVI) and Normalized Difference Water Index (NDWI) from Landsat data in the one-harvest area of the northern Loess Plateau of China by using the Google Earth Engine (GEE) platform. An extraction method was proposed for irrigated drylands in arid and semi-arid regions of northwest China. In addition, the change types of irrigated and rainfed drylands in the two periods were classified, and a method was also put forward to directly classify the change types by using the image differences between the two periods combined with the classification results of each period. It was found that combining the ratio of NDVI and NDWI with the accumulated values of temperature and precipitation of the 30 days before imaging could effectively improve the classification accuracy. Moreover, directly classifying the gaps of remote sensing factors in the time dimension before combining spatial clustering information could yield a more accurate type of change, because the accumulation of errors in the change maps obtained from the overlay analysis of distribution maps of the two periods could be avoided. The accuracy of classification could be improved by introducing the dynamic information of time dimension into the classification of historical periods. This study complements the extraction method for this type of irrigated dryland, and the classification results can improve the accuracy of existing products in terms of spatial resolution, which can fill the shortage of detailed distribution data for irrigated and rainfed drylands in this region.
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Wang, Zhi, Jiajia Zhou, Linjian Song i Long Li. "Experimental Study of Low Cycle Fatigue Properties for Epoxy Resins with Dibutyl Phthalate (Dbp)". Archives of Civil Engineering 64, nr 2 (31.12.2018): 147–59. http://dx.doi.org/10.2478/ace-2018-0021.
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AbstractIn order to improve the toughness of traditional epoxy resin, dibutyl phthalate (DBP) was introduced into the epoxy resin. The static mechanical performance of plasticized and unplasticized epoxy resin was evaluated. The test results showed that the DBP modified epoxy resin can obtain a higher toughness than conventional epoxy resin, but the elastic modulus and the tensile strength were slightly reduced. The low cycle fatigue test results indicated that the stress ratio and the stress level were two critical factors of fatigue life, which was increased with the growth of stress ratio. It was also found that the fatigue life of plasticized specimen was much less than that of the unplasticized specimen because of the plastic deformation. A logarithmic linear relationship was then established to predict the fatigue life for plasticized epoxy resin. The strain energy density was also applied to demonstrate the accumulation of energy loss. In addition, the fatigue toughness can be obtained by the hysteresis loop area method.
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Tawde, Sayli Atul, Anil V. Kulkarni i Govindasamy Bala. "An estimate of glacier mass balance for the Chandra basin, western Himalaya, for the period 1984–2012". Annals of Glaciology 58, nr 75pt2 (lipiec 2017): 99–109. http://dx.doi.org/10.1017/aog.2017.18.
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ABSTRACTAn improved understanding of fresh water stored in the Himalaya is crucial for water resource management in South Asia and can be inferred from glacier mass-balance estimates. However, field investigations in the rugged Himalaya are limited to a few individual glaciers and short duration. Therefore, we have recently developed an approach that combines satellite-derived snowlines, a temperature-index melt model and the accumulation-area ratio method to estimate annual mass balance of glaciers at basin scale and for a long period. In this investigation, the mass balance of 146 glaciers in the Chandra basin, western Himalaya, is estimated from 1984 to 2012. We estimate the trend in equilibrium line altitude of the basin as +113 m decade−1and the mean mass balance as −0.61 ± 0.46 m w.e. a−1. Our basin-wide mass-balance estimates are in agreement with the geodetic method during 1999–2012. Sensitivity analysis suggests that a 20% increase in precipitation can offset changes in mass balance for a 1 °C temperature rise. A water loss of 18% of the total basin volume is estimated, and 67% for small and low-altitude glaciers during 1984–2012, indicating a looming water scarcity crisis for villages in this valley.
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Sun, Yongshuai, Xinyan Zhong, Jianguo Lv i Guihe Wang. "Experimental Study on Silt Soil Improved by Microbial Solidification with the Use of Lignin". Microorganisms 11, nr 2 (20.01.2023): 281. http://dx.doi.org/10.3390/microorganisms11020281.
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At present, in the field of geotechnical engineering and agricultural production, with increasingly serious pollution an environmentally friendly and efficient means is urgently needed to improve the soil mass. This paper mainly studied the microbial induced calcium carbonate precipitation (MICP) technology and the combined effect of MICP technology and lignin on the improvement of silt in the Beijing area. Through unconfined compressive strength and dynamic triaxial test methods, samples improved by microorganisms were studied to obtain the optimal values of cement concentration and lignin under these two test schemes. The results show that after the incubation time of Sporosarcina pasteurii reached 24 h, the OD600 value was 1.7–2.0 and the activity value (U) was 930–1000 mM ms/min. In the unconfined static pressure strength test, after MICP treatment the optimal concentration of cementitious solution for constant temperature and humidity samples and constant-temperature immersion samples was 1.25 mol/L. The compressive strength of the constant temperature and humidity sample was 1.73 MPa, and the compressive strength of the constant-temperature immersion sample was 3.62 Mpa. At the concentration of 1.25 mol/L of cement solution, MICP technology combined with lignin could improve the constant temperature and humidity silt sample. The optimal addition ratio of lignin was 4%, and its compressive strength was 1.9 MPa. The optimal lignin addition ratio of the sample soaked at a constant temperature was 3%, and the compressive strength was 4.84 MPa. In the dynamic triaxial multi-stage cyclic load test, the optimal concentration of cementation solution for the constant temperature and humidity sample after MICP treatment was 1.0 mol/L, and the failure was mainly inclined cracks. However, in the condition of joint improvement of MICP and lignin, the sample mainly had a drum-shaped deformation, the optimal lignin addition ratio was 4%, and the maximum axial load that the sample could bear was 306.08 N. When the axial dynamic load reached 300 N, the strain accumulation of the 4% group was only 2.3 mm. In this paper, lignin, an ecofriendly material, was introduced on the basis of MICP technology. According to the failure shape and relevant results of the sample, the addition of lignin was beneficial for the improvement of the compressive strength of the sample.
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Yao, Lili, Qing Wang, Jinbo Yang, Yu Zhang, Yan Zhu, Weixing Cao i Jun Ni. "UAV-Borne Dual-Band Sensor Method for Monitoring Physiological Crop Status". Sensors 19, nr 4 (17.02.2019): 816. http://dx.doi.org/10.3390/s19040816.
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Unmanned aerial vehicles (UAVs) equipped with dual-band crop-growth sensors can achieve high-throughput acquisition of crop-growth information. However, the downwash airflow field of the UAV disturbs the crop canopy during sensor measurements. To resolve this issue, we used computational fluid dynamics (CFD), numerical simulation, and three-dimensional airflow field testers to study the UAV-borne multispectral-sensor method for monitoring crop growth. The results show that when the flying height of the UAV is 1 m from the crop canopy, the generated airflow field on the surface of the crop canopy is elliptical, with a long semiaxis length of about 0.45 m and a short semiaxis of about 0.4 m. The flow-field distribution results, combined with the sensor’s field of view, indicated that the support length of the UAV-borne multispectral sensor should be 0.6 m. Wheat test results showed that the ratio vegetation index (RVI) output of the UAV-borne spectral sensor had a linear fit coefficient of determination (R2) of 0.81, and a root mean square error (RMSE) of 0.38 compared with the ASD Fieldspec2 spectrometer. Our method improves the accuracy and stability of measurement results of the UAV-borne dual-band crop-growth sensor. Rice test results showed that the RVI value measured by the UAV-borne multispectral sensor had good linearity with leaf nitrogen accumulation (LNA), leaf area index (LAI), and leaf dry weight (LDW); R2 was 0.62, 0.76, and 0.60, and RMSE was 2.28, 1.03, and 10.73, respectively. Our monitoring method could be well-applied to UAV-borne dual-band crop growth sensors.
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Mehboob, Noman, Tauqeer Ahmad Yasir, Shahid Hussain, Shahid Farooq, Muhammad Naveed i Mubshar Hussain. "Osmopriming Combined with Boron-Tolerant Bacteria (Bacillus sp. MN54) Improved the Productivity of Desi Chickpea under Rainfed and Irrigated Conditions". Agriculture 12, nr 8 (20.08.2022): 1269. http://dx.doi.org/10.3390/agriculture12081269.
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Chickpeas are rich source of protein and predominantly grown in boron (B)-deficient sandy-loam soils in Pakistan. Boron-tolerant bacteria (BTB) could tolerate higher B levels in soil and increase B availability to the plants. Field trials were conducted under irrigated (district Layyah) and rainfed (district Chakwal) conditions to evaluate the interactive effects of pre-optimized B application methods and BTB (Bacillus sp. MN54) on the nodule’s population, grain quality, productivity, and grain-B concentration in desi chickpea during 2019–2020 and 2020–2021. Boron was applied as soil application (1 kg B ha−1), foliar application (0.025% B), osmopriming (0.001% B), and seed coating (1.5 g B kg−1 seed) with or without BTB inoculation. Untreated seeds receiving no B through any of the methods were regarded as control. The individual and interactive effects (up to three-way interaction of location × BTB inoculation × B application methods) of year, location, B application methods and BTB inoculation significantly altered the growth and yield-related traits of desi chickpea. The four-way interaction of year × location × BTB inoculation × B application methods was non-significant for all recorded growth and yield-related traits. Regarding individual effects, the higher values of growth and yield-related traits were noted for 2020–2021, rainfed location, BTB inoculation and B application through seed priming. Similarly, in two-way interactions 2020–2021 with rainfed location and BTB inoculation, rainfed location with BTB inoculation and osmopriming and osmopriming with BTB inoculation recorded higher values of the growth and yield-related traits. Osmopriming combined with BTB inoculation significantly improved dry matter accumulation and leaf area index in both locations. Boron application through all the methods significantly improved grain quality, yield grain B concentration. The highest grain and biological yields, and nodules’ population were recorded with osmopriming followed by soil application of B combined with BTB inoculation. The highest plant B concentration (75.05%) was recorded with foliar application of B followed by osmopriming (68.73%) combined with BTB inoculation. Moreover, the highest economic returns (USD 2068.5 ha−1) and benefit–cost ratio (3.7%) were recorded with osmopriming + BTB inoculation in 2020–2021 under rainfed conditions. Overall, B application through osmopriming and soil application combined with BTB inoculation could be used to increase productivity and profitability of desi chickpea, whereas foliar application is a better method to enhance grain and plant B concentration.
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Zhai, Yunlong, Quanzhong Wu, Guodong Chen, Hailin Zhang, Xiaogang Yin i Fu Chen. "Broadcasting Winter Wheat Can Increase Grain Yield without Reducing the Kernels per Spike and the Kernel Weight". Sustainability 10, nr 12 (19.12.2018): 4858. http://dx.doi.org/10.3390/su10124858.
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In North China, row spacing is the most common planting pattern used for winter wheat. Currently, there are three sowing and tillage methods for row spacing: rotary tillage sowing with straw return (RTS), subsoil tillage sowing with straw return (DTS), and no-tillage sowing with straw return (NTS). Recently, Hao proposed a new sowing pattern called uniform broadcast sowing with straw return (BSS) which could increase winter wheat yield. In this research, a field experiment was conducted during the growing seasons in 2011–2012 and 2012–2013. The winter wheat (Triticum aestivum L.) variety Jimai 22 was sowed with the four seeding and tillage methods—RTS, DTS, NTS, and BSS—at the China Agriculture University Wuqiao experimental station in the North China Plain. After tillage sowing and determining the sowing efficiency, the effective cover ratio of the seeds was measured, and the emergence ratio was calculated after emergence. In the two growing seasons, the growth and development stages were recorded. The dry matter accumulation (DMA), the yield, and the yield components (spikes per hectare, kernels per spike, and kernel weight) were also determined. We also measured the canopy structure leaf area index (LAI) and the stand uniformity. The results showed that BSS had the lowest emergence rate and lowest plant stands when compared with the other treatments. However, BSS had the highest grain yield at 7599.0 kg·ha−1 and 9763.3 kg·ha−1, which was 11.55, 16.17, 20.16% and 13.01, 15.68, 21.88% higher than DTS, RTS, and NTS in the 2011/2012 and 2012/2013 growing seasons, respectively. The improved grain yield of BSS was due to the increased productive tillers per hectometer-squared, which was attributed to the higher stand uniformity. More importantly, the increased tillers per hectare and grain yield were not accompanied by a reduction in grain number per spike or grain weight. The stand uniformity could facilitate canopy construction and population architecture and result in more even sunlight distribution, increased leaf area index (LAI) and sunlight interception, and enhanced photosynthetic activity. The stand uniformity also could increase both the pre-anthesis and post-anthesis DMA and promote the harvest index (HI). This study indicates that BSS is the most suitable sowing method for winter wheat production in North China.
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Cecato, Ulysses, Josmar Almeida Junior, Fabíola Cristine de Almeida Rego, Sandra Galbeiro, Wagner Paris, Carlos Alberto Scapim, Augusto Manoel Rodrigues i Glauber Marcelo Fakir. "Animal performance, production, and quality of Tanzania grass fertilized with nitrogen". Semina: Ciências Agrárias 38, nr 6 (23.11.2017): 3861. http://dx.doi.org/10.5433/1679-0359.2017v38n6p3861.
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This study aimed to assess forage production, animal performance, and the chemical composition of Tanzania grass pasture fertilized with 50, 100, 200, and 400 kg ha-1 of nitrogen. The variables analyzed were: leaf mass, daily accumulation rate, leaf/stem ratio, average daily gain, stocking rate, live weight gain per unit of area crude protein, neutral detergent fiber, and in vitro dry matter digestibility of leaves. The pasture management maintained the pasture height at 50 cm by using a continuous grazing method with the adjustment of stocking rate. The experimental design was a randomized block with three replicates. The leaf mass increased linearly in response to nitrogen, with an increase of 1003 kg (34%) observed between a nitrogen content of 50 and 400 kg ha-1. Nitrogen did not affect the average daily gain, but increased the stocking rate and live weight gain ha-1. The value of crude protein and neutral detergent fiber were higher with increased nitrogen levels, whereas the leaf digestibility did not affect nitrogen use. The comparison of 50 and 400 kg ha-1 levels indicated that there was an average increase of 19.2% in the leaf crude protein. The increased application of nitrogen fertilizer in Tanzania grass improved the chemical composition and animal performance; with regard to studied variables, the dose of 200 kg ha-1 resulted in the greatest improvement.
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Li, Xiang, Ninglian Wang i Yuwei Wu. "Automated Glacier Snow Line Altitude Calculation Method Using Landsat Series Images in the Google Earth Engine Platform". Remote Sensing 14, nr 10 (14.05.2022): 2377. http://dx.doi.org/10.3390/rs14102377.
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Glacier snow line altitude (SLA) at the end of the ablation season is an indicator of the equilibrium line altitude (ELA), which is a key parameter for calculating and assessing glacier mass balance. Here, we present an automated algorithm to classify bare ice and snow cover on glaciers using Landsat series images and calculate the minimum annual glacier snow cover ratio (SCR) and maximum SLA for reference glaciers during the 1985–2020 period in Google Earth Engine. The calculated SCR and SLA values are verified using the observed glacier accumulation area ratio (AAR) and ELA. We select 14 reference glaciers from High Mountain Asia (HMA), the Caucasus, the Alps, and Western Canada, which represent four mountainous regions with extensive glacial development in the northern hemisphere. The SLA accuracy is ~73%, with a mean uncertainty of ±24 m, for 13 of the reference glaciers. Eight of these glaciers yield R2 > 0.5, and the other five glaciers yield R2 > 0.3 for their respective SCR–AAR relationships. Furthermore, 10 of these glaciers yield R2 > 0.5 and the other three glaciers yield R2 > 0.3 for their respective SLA–ELA relationships, which indicate that the calculated SLA from this algorithm provides a good fit to the ELA observations. However, Careser Glacier yields a poor fit between the SLA calculations and ELA observations owing to tremendous surface area changes during the analyzed time series; this indicates that glacier surface shape changes due to intense ablation will lead to a misclassification of the glacier surface, resulting in deviations between the SLA and ELA. Furthermore, cloud cover, shadows, and the Otsu method limitation will further affect the SLA calculation. The post-2000 SLA values are better than those obtained before 2000 because merging the Landsat series images reduces the temporal resolution, which allows the date of the calculated SLA to be closer to the date of the observed ELA. From a regional perspective, the glaciers in the Caucasus, HMA and the Alps yield better results than those in Western Canada. This algorithm can be applied to large regions, such as HMA, to obtain snow line estimates where manual approaches are exhaustive and/or unfeasible. Furthermore, new optical data, such as that from Sentinel-2, can be incorporated to further improve the algorithm results.
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Mezzomo, Roberto F., Jose M. Luvizotto i Cesar L. Palagi. "Improved Oil Recovery in Carmópolis Field: R&D and Field Implementations". SPE Reservoir Evaluation & Engineering 4, nr 01 (1.02.2001): 4–10. http://dx.doi.org/10.2118/69811-pa.
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Summary Carmópolis field, in northeastern Brazil's Sergipe/Alagoas basin, is the country's largest onshore oil accumulation at 253×106 m3 original oil in place (OOIP) and a current total oil production of 2880 m3/d. Discovered in 1963, it was quickly put into primary production. Waterflooding followed in 1971 at the central portion of the field. The combination of adverse fluid mobility ratio, reservoir heterogeneity, and the lack of proper selective injection led to the quick decline of production; however, a major program of selective plugging, stimulation, and selective injection was able to stabilize production immediately. Waterflooding was then extended to the entire main block of the field. The well pattern was changed from five- to nine-spot arrangement, with a corresponding downsizing in well spacing and injection rates. Carmópolis also was subjected to an intense improved oil recovery (IOR) campaign with pilot tests on polymer flooding, steamflooding and in-situ combustion. The history of Carmópolis field and the significance of waterflooding to oil production in Brazil, with approximately 2000×106 m3 OOIP currently submitted to this method of recovery, led to the selection of Carmópolis as the target for one of the projects in the PRAVAP (Petrobras Strategic IOR Program) portfolio. The scope of this project included a review of the waterflooding operation through improved reservoir characterization and flow simulation, as well as the investigation of other IOR methods that might reverse the declining production trend. This paper reviews the IOR history of Carmópolis field and summarizes the outcome of the PRAVAP project that led to the approval of field implementations worth U.S. $34 million net present value (NPV). Introduction Waterflooding has come a long way since its accidental implementation in 1865,1 in the area around the city of Pithole, Pennsylvania. Less than a century later, this improved method of recovery was responsible for more than 10% of the total oil production in the U.S. By 1986, this share was thought to be in the 50% range.2 This scenario is not any different around the world, especially in major producing regions like the former USSR and the Middle East. A good example is the giant field of Ghawar in Saudi Arabia, already partially under waterflooding. The situation in Brazil is very similar. Close to 2000×106 m3 OOIP are currently under the influence of water injection. In the near future, water injection rates will reach more than 500 000 m3/d in the discovered fields of Campos basin. In that basin, water injection in Marlim field alone is expected to peak around 100 000 m3/d. In fact, the history of waterflooding in Brazil dates back to the early 1950's, and Carmópolis field onshore Sergipe/Alagoas basin, as shown in Fig. 1, is a very characteristic part of it. Discovered in 1963 and quickly brought on stream, it produces predominantly from the sandstone and conglomerate reservoirs of the Carmópolis/Muribeca formation and secondarily from the deeper Barra de Itiuba formation and the fractured basement (see Fig. 2). Accordingly, oil quality varies considerably throughout the stratigraphic column. General reservoir data is given in Table 1; for a good description of the reservoir geology, refer to Candido and Wardlaw.3 This paper focuses on the review of IOR applications in Carmópolis field over the past 28 years, the results of the recently concluded project within the PRAVAP portfolio, and the corresponding field pilot implementations. History of IOR Applications in Carmópolis Field Waterflooding. Waterflooding was first implemented in Carmópolis field in 1968 on a 65-ha inverted nine-spot pattern in the southern part of the field. The target was the 2.97×106 m3 OOIP in zones CPS-1, −2 and −3. This project was operated for 3 years at an injection rate of 0.01 PV/yr, with no significant results. Injection was then confined to zones CPS-1 and −2 alone; still, after 2 years of close monitoring, results were inconclusive. Eventually, poor performance led to project abandonment. Meanwhile, in 1971, waterflooding had been initiated at the main block of the field, where substantial reservoir depletion (40 kg/cm2) had led to an average well productivity decline of 30%. The project was designed as nine inverted nine-spot patterns occupying an area of 576 ha. The target oil was 42×106 m3 in zones CPS-1, −2, −3, and −4 of the Carmópolis/Muribeca formation, as well as the reservoirs in the Barra de Itiuba formation. The final estimated recovery factor (FR) was 25.3% for a projected injection rate of 1800 m3/d (200 m3/d/well). During this 8-year project, injection in the Barra de Itiuba formation and zones CPS-3 and −4 of the Carmópolis/Muribeca was suspended owing to the high oil viscosity in the former and the bad quality of the conglomerate reservoirs in the latter. Despite the difficulties in managing selective injection, the project was considered an overall success. Reservoir pressure was restored and well productivity increased. However, the price hike that culminated with the second oil shock of 1979, as well as the fact that the project life expectancy was estimated at 30 years under the original design specifications, led to an effort to upgrade the project design to anticipate production from that area of the field. The result was the conversion of the original nine-spot arrangement of the waterflooding operation to 44 inverted five-spot patterns of 8 ha each, with water injection concentrated in zones CPS-1 and −2 alone. Forty-four new injectors and 28 production wells were drilled and completed only in zones CPS-1 and −2 for a target oil of 15×106 m3. Former injection wells were converted into producers. Injection began in April 1978 at a rate of 100 m3/d/well totaling 4400 m3/d for the entire operation. Because of the downsizing in well patterns and the increase in injection rate, oil production in the area rose from 600 to 800 m3/d within 3 years. Water/oil ratio then began to increase sharply with massive water breakthrough in the producing wells. Originally thought to be simply inherent to the higher injection rates, this breakthrough was later found to be associated to the high mobility ratio of the fluid displacement and reservoir high-permeability streaks. Together with the decrease of the injection rate and the extension of completion to zone CPS-3, an ambitious program of injection well profile modification, through stimulation and selectivity plugging, was implemented. It ensured the maintenance of oil production at acceptable levels up to the mid-1980's. By 1986, however, with the profile modification treatments losing their effectiveness, production went into a sharp decline once again. Fig. 3 gives an overall view of the exploitation history in the main block of Carmópolis field.
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Hai, Yang, Ling Zuo, Meng Wang, Ruoyu Zhang, Munan Wang, Li Ren, Congwen Yang i Jianwei Wang. "Icariin Alleviates Nonalcoholic Fatty Liver Disease in Polycystic Ovary Syndrome by Improving Liver Fatty Acid Oxidation and Inhibiting Lipid Accumulation". Molecules 28, nr 2 (5.01.2023): 517. http://dx.doi.org/10.3390/molecules28020517.
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(1) Background: Icariin is the main component of the Chinese herb Epimedium. A number of studies have shown that it alleviates abnormal lipid metabolism. However, it is not clear whether and how icariin can ameliorate hepatic steatosis with polycystic ovary syndrome (PCOS). This study was designed to explore the anti-hepatosteatosis effect of icariin in rats with polycystic ovary syndrome. (2) Methods: Female Sprague Dawley(SD)rats were treated with a high-fat diet and letrozole for 21 days to make nonalcoholic fatty liver disease (NAFLD) in the polycystic ovary syndrome model. Then model rats were treated with icariin (by gavage, once daily) for 28 days. Serum hormones and biochemical variables were determined by ELISA or enzyme. RNA-sequence analysis was used to enrich related target pathways. Then, quantitative Real-time PCR (qRT-PCR) and Western blot were performed to verify target genes and proteins. (3) Results: Icariin treatment reduced excess serum levels of Testosterone (T), Estradiol (E2), Luteinizing hormone (LH), Follicle-stimulating hormone (FSH), LH/FSH ratio, insulin, triglycerides (TG), and aspartate aminotransferase (AST) in high-fat diet (HFD) and letrozole fed rats. Meanwhile, icariin ameliorated HFD and letrozole-induced fatty liver, as evidenced by a reduction in excess triglyceride accumulation, vacuolization, and Oil Red O staining area in the liver of model rats. Results of RNA-sequencing, western blotting, and qRT-PCR analyses indicated that icariin up-regulated fatty acid translocase (CD36), in mitochondria, and peroxisome proliferator-activated receptor α (PPARα) expression, which led to the enhancement of fatty acid oxidation molecules, such as cytochrome P450, family 4, subfamily a, polypeptide 3 (CYP4A3), carnitine palmitoyltransferase 1 α (CPT1α), acyl-CoA oxidase 1 (ACOX1), medium-chain acyl-CoA dehydrogenase (MCAD), and long-chain acyl-CoA dehydrogenase (LCAD). Besides, icariin reduced lipid synthesis, which elicited stearoyl-Coenzyme A desaturase 1 (SCD1), fatty acid synthase (FASN), and acetyl-CoA (ACC). (4) Conclusion: Icariin showed an ameliorative effect on hepatic steatosis induced by HFD and letrozole, which was associated with improved fatty acid oxidation and reduced lipid accumulation in the liver.
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Wang, Jiaqiang, Jie Peng, Hongyi Li, Caiyun Yin, Weiyang Liu, Tianwei Wang i Huaping Zhang. "Soil Salinity Mapping Using Machine Learning Algorithms with the Sentinel-2 MSI in Arid Areas, China". Remote Sensing 13, nr 2 (17.01.2021): 305. http://dx.doi.org/10.3390/rs13020305.
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Accurate monitoring of soil salinization plays a key role in the ecological security and sustainable agricultural development of arid regions. As a branch of artificial intelligence, machine learning acquires new knowledge through self-learning and continuously improves its own performance. The purpose of this study is to combine Sentinel-2 Multispectral Imager (MSI) data and MSI-derived covariates with measured soil salinity data and to apply three machine learning algorithms in modeling to estimate and map the soil salinity in the study sample area. According to the convenient transportation conditions, the study area and sampling quadrat were set up, and the 5-point method was used to collect the soil mixed samples, and 160 soil mixed samples were collected. Kennard–Stone (K–S) algorithm was used for sample classification, 70% for modeling and 30% for verification. The machine learning algorithm uses Support Vector Machines (SVM), Artificial Neural Network (ANN), and Random Forest (RF). The results showed that (1) the average reflectance of each band of the MSI data ranged from 0.21–0.28. According to the spectral characteristics corresponding to different soil electrical conductivity (EC) levels (1.07–79.6 dS m−1), the spectral reflectance of salinized soil in the MSI data ranged from 0.09–0.35. (2) The correlation coefficient between the MSI data and MSI-derived covariates and soil EC was moderate, and the correlation between certain MSI data sets and soil EC was not significant. (3) The SVM soil EC estimation model established with the MSI data set attained a higher performance and accuracy (R2 = 0.88, root mean square error (RMSE) = 4.89 dS m−1, and ratio of the performance to the interquartile range (RPIQ) = 1.96, standard error of the laboratory measurements to the standard error of the predictions (SEL/SEP) = 1.11) than those attained with the soil EC estimation models established with the RF and ANN models. (4) We applied the SVM soil EC estimation model to map the soil salinity in the study area, which showed that the farmland with higher altitudes discharged a large amount of salt to the surroundings due to long-term irrigation, and the secondary salinization of the farmland also caused a large amount of salt accumulation. This research provides a scientific basis for the simulation of soil salinization scenarios in arid areas in the future.
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Rastner, Philipp, Rainer Prinz, Claudia Notarnicola, Lindsey Nicholson, Rudolf Sailer, Gabriele Schwaizer i Frank Paul. "On the Automated Mapping of Snow Cover on Glaciers and Calculation of Snow Line Altitudes from Multi-Temporal Landsat Data". Remote Sensing 11, nr 12 (14.06.2019): 1410. http://dx.doi.org/10.3390/rs11121410.
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Mapping snow cover (SC) on glaciers at the end of the ablation period provides a possibility to rapidly obtain a proxy for their equilibrium line altitude (ELA) which in turn is a metric for the mass balance. Satellite determination of glacier snow cover, derived over large regions, can reveal its spatial variability and temporal trends. Accordingly, snow mapping on glaciers has been widely applied using several satellite sensors. However, as glacier ice originates from compressed snow, both have very similar spectral properties and standard methods to map snow struggle to distinguish snow on glaciers. Hence, most studies applied manual delineation of snow extent on glaciers. Here we present an automated tool, named ‘ASMAG’ (automated snow mapping on glaciers), to map SC on glaciers and derive the related snow line altitude (SLA) for individual glaciers using multi-temporal Landsat satellite imagery and a digital elevation model (DEM). The method has been developed using the example of the Ötztal Alps, where an evaluation of the method is possible using field-based observations of the annual equilibrium line altitude (ELA) and the accumulation area ratio (AAR) measured for three glaciers for more than 30 years. The tool automatically selects a threshold to map snow on glaciers and robustly calculates the SLA based on the frequency distribution of elevation bins with more than 50% SC. The accuracy of the SC mapping was about 90% and the SLA was determined successfully in 80% of all cases with a mean uncertainty of ±19 m. When cloud-free scenes close to the date of the highest snowline are available, a good to very good agreement of SC ratios (SCR)/SLA with field data of AAR/ELA are obtained, otherwise values are systematically higher/lower as useful images were often acquired too early in the summer season. However, glacier specific differences are still well captured. Snow mapping on glaciers is impeded by clouds and their shadows or when fresh snow is covering the glaciers, so that more frequent image acquisitions (as now provided by Sentinel-2) would improve results.
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Jiao, Huazhe, Wenbo Yang, Huiming Shen, Yingjie Yang i Juanhong Liu. "Study on Multi-Layer Filling Treatment of Extra-Large Goaf and Its Underground Application". Materials 15, nr 16 (18.08.2022): 5680. http://dx.doi.org/10.3390/ma15165680.
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At present, the many domestic, large mined-out areas caused by single filling ability of the slurry flow state, thin layer flow and hardening after filling in multilayer structure generally need to finish filling for many times, because after a filling experience shows that filling body in the last solidification of flow, this leads to a lower one side of the roof, and far distance part of the filling body cannot pick up top. The determination of backfill strength is the key problem of the cemented backfill method, and it is affected by many factors. Therefore, through theoretical calculation, laboratory testing and numerical simulation methods, combined with the field filling process, this paper has verified the flow accumulation and stratification characteristics of stope layered filling slurry. When the slurry concentration is 60–73%, the slope increases exponentially from 2.5° to 8°. It is revealed that the delamination and meshing state are the key factors to determine the overall strength of large-scale stope filling through the testing of particle size distribution in interlayer and flow direction. The reduction effect of the number and Angle of structural weak surface formed by layering and filling on strength is revealed: cement–sand ratio 1:12, concentration 68%, standard curing R28 > 1.81 MPa. The strength reduction coefficient is 61.31% and 92.96% when the number of layers is 1–4. The higher the number of layers, the greater is the reduction coefficient, and when the stratification angle increases by 2, the strength of backfill decreases by 20–30%. The verification of stope filling coring shows that the in situ strength reaches 2.42 MPa, which is 0.61 MPa higher than the standard curing strength, with an increase of 33.7%. When the depth is from 1 m to 5 m, the strength increases from 2.26 MPa to 2.69 MPa, with an increase rate of 18.2%. Finally, through the research and application of the comprehensive technology of mining and filling coordination under the complex goaf group, the residual ore resources of Xianglushan tungsten mine are effectively recovered, the volume of goaf is significantly reduced, and the safety of goaf is improved.
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Huseby, Olaf K., Mona Andersen, Idar Svorstol i Oyvind Dugstad. "Improved Understanding of Reservoir Fluid Dynamics in the North Sea Snorre Field by Combining Tracers, 4D Seismic, and Production Data". SPE Reservoir Evaluation & Engineering 11, nr 04 (1.08.2008): 768–77. http://dx.doi.org/10.2118/105288-pa.
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Summary To obtain improved oil recovery (IOR), it is crucial to have a best-possible description of the reservoir and the reservoir dynamics. In addition to production data, information can be obtained from 4D seismic and from tracer monitoring. Interwell tracer testing (IWTT) has been established as a proven and efficient technology to obtain information on well-to-well communication, heterogeneities, and fluid dynamics. During such tests, chemical or radioactive tracers are used to label water or gas from specific wells. The tracers then are used to trace the fluids as they move through the reservoir together with the injection phase. At first tracer breakthrough, IWTT yields immediate and unambiguous information on injector/producer communication. Nevertheless, IWTT is still underused in the petroleum industry, and data may not be used to their full capacity--most tracer data are used in a qualitative manner (Du and Guan 2005). To improve this situation, we combine tracer-data evaluation, 4D seismic, and available production data in an integrated process. The integration is demonstrated using data from the Snorre field in the North Sea. In addition to production data, extensive tracer data (dating back to 1993) and results from three seismic surveys acquired in 1983, 1997, and 2001 were considered. Briefly this study shows thatSeismic and tracer data applied in combination can reduce the uncertainties in interpretations of the drainage patterns.Waterfronts interpreted independently by tracer response and seismic dimming compare well.Seismic brightening interpreted as gas accumulation is supported by the gas-tracer responses. Introduction The Snorre field is located in the Tampen Spur area on the Norwegian continental shelf and is a system of rotated fault blocks with beds dipping 4 to 10° toward the northwest. The reservoir sections are truncated by the Base Cretaceous unconformity. The reservoir sections consist of fluvial deposits of the Statfjord and Lunde formations. The reservoir units contain thin sand layers with alternating shale in a complex fault pattern. A challenge regarding optimization of the reservoir drainage, as well as oil production, is to understand how the different sand layers communicate and to what degree the faults act as barriers or not. The present work concentrates on the integration of 4D-seismic and tracer methods to obtain information on fluid flow in the Upper Statfjord (US) and Lower Statfjord (LS) formations in the Central Fault Block (CFB). The outline of this fault block is indicated in Fig. 1. The net/gross ratio is higher and the reservoir quality is generally better in the US than the LS formation. The CFB is produced by water-alternating-gas (WAG) injection as the drive mechanism, where the injectors are placed downdip and the producers updip. The average reservoir pressure in the CFB is 300 bar, and the reservoir temperature is 90°C. Tracer data are used to understand fluid flow in the reservoir. The data give valuable information about the dynamic behavior and well communication, but in some cases the interpretation may be complicated by reinjection of produced gas and water. Tracer studies in the Snorre field have been presented previously in several papers (Dugstad et al. 1999; Ali et al. 2000; Aurdal et al. 2001). To use the data fully, however, integration with other types of reservoir data is important. The main objectives of the seismic monitoring of Snorre are to contribute to increased oil recovery and to optimize placement of new wells. 4D analysis, together with tracers, should potentially increase the multidisciplinary understanding of the drainage pattern in the reservoirs. The results should, in addition to all the reservoir and production data, be used actively in target-remaining-oil processes and in well planning. In addition, the 4D data can give input to update the geological model and simulation model (history matching) and to identify possible well interventions. There is also a potential to include the data in workflows to identify lithology changes.
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Kurita, Hisatsugu, Masataka Nakamura, Hayato Miyagawa i Yoshiaki Kamigaki. "Effect of N2-Anneal Temperature on Silicon Nitride Film: (I) Time-Dependent Dielectric Breakdown and ESR Evaluations". ECS Meeting Abstracts MA2022-01, nr 28 (7.07.2022): 1250. http://dx.doi.org/10.1149/ma2022-01281250mtgabs.
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Silicon Nitride (SiN) film has been used as insulating material in many electronic devices such as capacitors and memories . In this report, the effect of N2 anneal temperature on charge break down (Qbd) of LP-CVD SiN film was electrically evaluated using the time-dependent dielectric breakdown (TDDB) test method, and the variation and the density of defects which exist in SiN film, in the oxide layer between SiN and Si substrate, and at the surface of Si substrate, were investigated using an Electron Spin Resonance (ESR) to reveal the defect behavior related to the trigger of Qbd. SiN metal-insulator-metal (MIM) capacitors were fabricated to evaluate TDDB. A 54 nm dielectric layer of SiN film was deposited at 700 degree-C, using a mixture of dichlorosilane（SiH2Cl2）and ammonia (NH3) gasses, by a LP-CVD vertical furnace. For the lower and upper electrode, a 400 nm polycrystalline silicon films were deposited using a LP-CVD. In order to evaluate the effect of anneal temperature on SiN film breakdown frequency, these samples were annealed in nitrogen atmosphere at temperatures between 700 and 1150 degree-C for 1 hour, using a vertical furnace. Breakdown voltage was measured with a current-voltage tester (HP4071A, Hewlett Packard) for each SiN MIM capacitor. The breakdown frequency was defined as the ratio of failed capacitors to tested capacitors. For the TDDB measurements, a constant current stress of 1.33 A/cm2 was applied to the MIM capacitors with the area of 0.00375cm2, 0.0075cm2, 0.015cm2 and 0.03cm2. For each area, 100 chips were made from one wafer and measured. In Fig.1, SiN film breakdown frequency increases toward a peak at around the N2 anneal temperature of 900 degree-C, then decreases at 1000 degree-C, and at more than 1100 degree-C, the frequency increases again drastically at 1150 degree-C. SiN films for ESR study were fabricated on Si wafer in the same LP-CVD process, and annealed in nitrogen atmosphere at temperatures between 700 and 1150 degree-C for 1 hour, using a vertical furnace. The ESR measurements were performed at room temperature using an X-band spectrometer (JES-RE1X). To improve the signal-to-noise ratio of an ESR signal waveform, we set the accumulation number of magnetic-field (H) sweep about 300 times. Mn2+/ MgO hyperfine lines were used for the g marker, and spin densities were determined by using the standard of known spin content. In Fig.2, Dangling bond density at silicon interface (Pb center) has a peak at 900 degree-C, and those in SiO2 (E’ center) and SiN film (K center) increase with increasing temperature from 1000 to 1150 degree-C. The former phenomena of Pb center coincides with the peak of SiN film breakdown frequency at 900 degree-C, and the latter one of E’ center and K center coincides with the tendency of increasing Qbd frequency at more than 1000 degree-C. Figure 1
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Liu, Hui, Fabio Fiorani, Ortrud Jäck, Tino Colombi, Kerstin A. Nagel i Martin Weih. "Shoot and Root Traits Underlying Genotypic Variation in Early Vigor and Nutrient Accumulation in Spring Wheat Grown in High-Latitude Light Conditions". Plants 10, nr 1 (18.01.2021): 174. http://dx.doi.org/10.3390/plants10010174.
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Plants with improved nutrient use efficiency are needed to maintain and enhance future crop plant production. The aim of this study was to explore candidate traits for pre-breeding to improve nutrient accumulation and early vigor of spring wheat grown at high latitudes. We quantified shoot and root traits together with nutrient accumulation in nine contrasting spring wheat genotypes grown in rhizoboxes for 20 days in a greenhouse. Whole-plant relative growth rate was here correlated with leaf area productivity and plant nitrogen productivity, but not leaf area ratio. Furthermore, the total leaf area was correlated with the accumulation of six macronutrients, and could be suggested as a candidate trait for the pre-breeding towards improved nutrient accumulation and early vigor in wheat to be grown in high-latitude environments. Depending on the nutrient of interest, different root system traits were identified as relevant for their accumulation. Accumulation of nitrogen, potassium, sulfur and calcium was correlated with lateral root length, whilst accumulation of phosphorus and magnesium was correlated with main root length. Therefore, special attention needs to be paid to specific root system traits in the breeding of wheat towards improved nutrient accumulation to counteract the suboptimal uptake of some nutrient elements.
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Tang, G., X. Zhu, B. Hu, J. Xin, L. Wang, C. Münkel, G. Mao i Y. Wang. "Vertical variations of aerosols and the effects responded to the emission control: application of lidar ceilometer in Beijing during APEC, 2014". Atmospheric Chemistry and Physics Discussions 15, nr 9 (5.05.2015): 13173–209. http://dx.doi.org/10.5194/acpd-15-13173-2015.
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Abstract. During the 2014 Asia-Pacific Economic Cooperation (APEC) summit, a reduction of air pollution sources was coordinated to ensure good air quality in Beijing and the surrounding provinces and cities. By investigating variations in air pollution during this period, the effects of local emissions and regional transport can be better understood and the information can be used to evaluate the effectiveness of emission reduction strategies and provide a theoretical basis to guide future emission reduction strategies. From 15 October to 30 November 2014, the height of the atmospheric mixing layer and the aerosol attenuated backscattering coefficient profile were observed online using a lidar ceilometer. By investigating the correlation between fine particulate matter (PM2.5) data near the surface and attenuated backscattering coefficients measured by the lidar ceilometer as well as the correlation between aerosol optical depth (AOD) and attenuated backscattering coefficients of the 0 to 4500 m column, we found that the attenuated backscattering coefficient measured by the lidar ceilometer is highly correlated with the PM2.5 concentration and AOD (correlation coefficients of 0.89 and 0.86, respectively). This result demonstrates the reliability of the vertical profile of aerosols measured by the lidar ceilometer. By analyzing the atmospheric backscattering profile, we found that during the initial stage of pollution accumulation, which is affected by transport of southerly jet flows at low altitude, the attenuated backscattering coefficient of atmospheric aerosols from 0 to 1500 m was greatly enhanced by approximately 1.4 Mm-1 sr-1 (140%). At the peak pollution stage, the height of the mixing layer gradually decreased, the ratio of CO/SO2 gradually increased and emissions were dominated by local emissions. The attenuated backscattering coefficient of aerosols from 0 to 300 m suddenly increased, and the aerosols near surface had the highest value (approximately 14 Mm-1 sr-1); however, the attenuated backscattering coefficient of aerosols from 300 to 900 m gradually decreased, and the average value from 0 to 1500 m decreased by 0.5 Mm-1 sr-1 (20%). By comparing the PM2.5 concentrations before, during and after APEC (BAPEC, DAPEC and AAPEC, respectively), we found that the concentration of fine particles decreased by 60% and visibility improved by 60% during APEC. In addition, compared with the BAPEC and AAPEC periods, the contribution of regional transport in the DAPEC period decreased by approximately 36 and 25%, respectively, and the local contribution decreased by approximately 48 and 54%, respectively. Thus, the most effective method of controlling air pollution in the Beijing area is to reduce regional emissions during the initial stage of air pollution and reduce local emissions during the peak pollution stage.
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Lou, Haiyang, Rujiang Hao, Jianchao Zhang i Qiang Xue. "Application of Improved Phase Lock Method in Weak Signal Extraction". Mathematical Problems in Engineering 2022 (25.02.2022): 1–17. http://dx.doi.org/10.1155/2022/9137927.
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The existing method of the weak signal under the background of strong noise (signal amplitude relative to the noise amplitude is much smaller) analysis is not very ideal. This study proposes an improved phase lock method to analyze the weak periodic signal under Gaussian white noise. Experimental results show that this method can better analyze weak signal-related information than the stochastic resonance method in a certain range of signal-to-noise ratio, and the amount of calculation is small, and the correlation theory is simple and adapted to the rapid detection of the signal; in order to further reduce the amount of calculation, the introduction of a high-order accumulation of the signal presence detection, experiments verify that the high-order accumulation can detect whether there is a weak signal in the Gaussian noise. The combination of high-order cumulant and improved phase lock method has a good effect on the analysis of weak periodic signals under strong noise backgrounds.
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Cramer, GR, GJ Alberico i C. Schmidt. "Leaf Expansion Limits Dry Matter Accumulation of Salt-Stressed Maize". Functional Plant Biology 21, nr 5 (1994): 663. http://dx.doi.org/10.1071/pp9940663.
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Two maize (Zea mays L.) hybrids, differing in their salt tolerance (percentage of control on a dry weight basis) and ability to accumulate Na+ in the shoot, were treated with 80 mol m-3 NaCl salinity or 80 mol m-3 NaCl plus 8.75 mol m-3 CaCl2. Multiple harvests were performed and the interactions of salinity with time were examined with growth analysis. Relative growth rate (RGR) and leaf area ratio (LAR) were significantly reduced by NaCl salinity, but net assimilation rate (NAR) was unaffected. Supplemental Ca2+ improved RGR by maintaining LAR closer to control values. LAR was inhibited in the early stages of salt stress, but was not limiting growth relative to controls in later stages. Salinity also reduced the specific leaf area and leaf weight ratio, which indicates that leaf expansion and carbon allocation were altered. Differences in salt tolerance between the hybrids were small, but significant throughout the lifecycle of the plants. These differences were associated with differences in leaf elongation rates and LAR within the first 9 days of salinity.
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Odongo, Rhoda A., Hans De Moel i Anne F. Van Loon. "Propagation from meteorological to hydrological drought in the Horn of Africa using both standardized and threshold-based indices". Natural Hazards and Earth System Sciences 23, nr 6 (28.06.2023): 2365–86. http://dx.doi.org/10.5194/nhess-23-2365-2023.
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Abstract. There have been numerous drought propagation studies in data-rich countries, but not much has been done for data-poor regions (such as the Horn of Africa, HOA). In this study, we characterize meteorological, soil moisture and hydrological drought and the propagation from one to the other for 318 catchments in the HOA to improve understanding of the spatial variability in the drought hazard. We calculate the standardized precipitation index (SPI), standardized soil moisture index (SSMI) and standardized streamflow index (SSI). In addition, we use the variable threshold method to calculate the duration of drought below a predefined percentile threshold for precipitation, soil moisture and discharge. The relationship between meteorological and soil moisture drought is investigated by finding the SPI accumulation period that has the highest correlation between SPI and SSMI, and the relationship between meteorological and hydrological drought is analysed by the SPI accumulation period that has the highest correlation between SPI and SSI time series. Additionally, we calculated these relationships with the ratio between the threshold-based meteorological-drought duration and soil moisture drought duration and the relation between threshold-based meteorological-drought duration and streamflow drought duration. Finally, we investigate the influence of climate and catchment characteristics on these propagation metrics. The results show that (1) the propagation from SPI to SSMI and the mean drought duration ratio of meteorological to soil moisture drought (P / SM) are mainly influenced by soil properties and vegetation, with the short accumulation periods (1 to 4 months) of SPI in catchments with arable land, high mean annual precipitation, and low sand and silt content, while longer accumulations (5 to 7 months) are in catchments with low mean annual upstream precipitation and shrub vegetation; (2) the propagation from SPI to SSI and precipitation-to-streamflow duration ratio are highly influenced by the climate and catchment control, i.e. geology, elevation and land cover, with the short accumulation times in catchments with high annual precipitation, volcanic permeable geology and cropland and the longer accumulations in catchments with low annual precipitation, sedimentary rocks and shrubland; and (3) the influence of mean annual upstream precipitation is more important for the propagation from SPI to SSI than from SPI to SSMI. Additionally, precipitation accumulation periods of approximately 1 to 4 months in wet western areas of the HOA and of approximately 5 to 7 months in the dryland regions are found. This can guide forecasting and management efforts as different drought metrics are thus of importance in different regions.
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Wang, Cheng, i Bing Yi Li. "CVT Ratio Adjusting Process Control". Advanced Materials Research 139-141 (październik 2010): 1929–32. http://dx.doi.org/10.4028/www.scientific.net/amr.139-141.1929.
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Aiming at the shortcoming of the integral accumulation in the process of CVT ratio adjusting control, which is caused by the general PID control method, a new ratio adjusting control system based on the shift integral PID control method was designed. The theory of CVT ratio adjusting process and the enhanced control method were analized. The enhanced PID parameter tuning principle was presented. The test-bed of CVT ratio adjusting control was devised and adopted to do the CVT ratio tracing experiments. The experiments of step ratio from 0.45 to 1.45 and from 1.7 to 0.7 were made. The experimental results proved that the new ratio adjusting control system and the enhanced PID parameter tuning principle were valid, which made the real ratio trace the object ratio rapidly and steadily. The control performance of CVT ratio adjusting was improved.
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Kopylov, K. V., i K. V. Kopylova. "STUDY OF NON-CODING AREAS OF THE DNA GENOME OF DIFFERENT ANIMAL SPECIES". Animal Breeding and Genetics 65 (3.07.2023): 184–90. http://dx.doi.org/10.31073/abg.65.17.
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The introduction to the review article contains information that the genome is the totality of the DNA of a species, that is, the totality of all genes, non-coding regions of nuclear DNA and extrachromosomal genetic material, which includes mitochondrial, plastid DNA, plasmids, etc. An exon is a stretch of DNA within a gene that is translated into a mature matrix RNA (mRNA) molecule by transcription and splicing. They are separated by non-coding sequences (introns), that is, sections of DNA that are part of the gene, but, unlike exons, do not contain information about the amino acid sequence. In many organisms, only a small part of 2%–6% of the total genome sequence encodes proteins, and more than 90% of DNA consists of non-coding DNA sequences, satellite DNA, introns, tandem repeats, transposons, etc.). Non-coding sequences are sections of DNA whose sequence is not translated directly into the amino acid sequence of proteins.
As a research method, the authors declared a systematic approach to the study of factual materials, conducted a study of factual material and generalized their results.
The research results are as follows. The use of genotyping technologies and the use of molecular analysis methods made it possible to obtain an individual characteristic of an individual genotype – a DNA profile. Modern methods of DNA typing of genomes differ in complexity, reliability, and amount of information obtained. The most promising method is the analysis of polymorphism of hypervariable genome sequences, which makes it possible to obtain reproducible, informative profiles of genome fragments. DNA sequences are divided into multilocus (RAPD, AFLP, ISSR) and monolocus (STMS, SNP, SSCP) and others. The study of multilocus markers is based on the use of the polymerase chain reaction (PCR). The essence of the ISSR-PCR method (Inter-simple-sequence-repeats) is the use of microsatellite loci as primer firing sites that are complementary to microsatellite repeats (4–12 repeat units) and have 1–4 anchors at one 5' or 3' end. Such primers allow the amplification of DNA fragments located between microsatellite sequences. RAPD – markers (Random Amplified Polymophic DNA) – the essence of the method is to conduct a polymerase chain reaction using a primer with an arbitrary sequence of 10–12 nucleotides. For the synthesis of these primers, it is not necessary to know the specific nucleotide sequences of the genome, they must only meet the requirements for the ratio of GC pairs (about 60%) in length. AFLP (Amplified fragment length polymorphism) - amplified fragment length polymorphism (AFLP markers). The essence of the method is that DNA is treated with a combination of two restrictases. Specific adapters are ligated to sticky ends and the fragments are amplified using primers containing sequences in common with the adapters and 1–3 random bases. The set of resulting fragments depends on the restriction enzyme and primer extensions used. The primers have a fixed part with a complementary sequence of the adapter and the restriction site of the used endonuclease (~ 15 nucleotides), and a fragment at (at the 3'-end) with an arbitrary nucleotide sequence (2–4 nucleotides). The fixed part gives the primer stability, and the short part allows you to determine and control the proportion of ligated fragments. From each pair of primers, 75–100 fragments are amplified (AFLP - fingerprinting). AFLP markers are often inherited as tightly linked clusters in the centromere or telomere regions of chromosomes and have a dominant mode of inheritance. AFLP markers are used for genomic mapping in population and phylogenetic studies. Repeat sequences are divided into two classes: dispersed sequences and tandem repeats. Dispersed sequences, depending on their length, are classified into long interdispersion elements (LINEs) with a length of more than 1000 b. p. and short (SINEs) – less than 500 b. p. Depending on the length of the repeating fragments, they are divided into several classes: maxi (length over 5 x 105 b. p.), mini (length of the tandem repeating sequence 10–60 b. p.) and microsatellites with a motif length of 1–6 b. p. Minisatellites are used in "genomic fingerprinting" (DNA fingerprinting). The main mechanism for the emergence and existence of polymorphism in minisatellites is considered to be unequal crossing over and gene conversion, and high variability is associated with the mutation initiator flanking the repeat and activation of the mutagenic systems of the genome. The microsatellites are dispersed in tandem repeating mono-, di-, tri-, tetra-, and pentanucleotide sequences, which average less than 100 b. p. in size. They are a universal system of genetic markers for the analysis of configurations inherited at the level of nuclear DNA and used in animal husbandry.
The make the conclusion that molecular approaches make it possible to compare very distant organisms, and it is also important that the range of objects from which DNA suitable for analysis can be isolated continues to expand. The genome analysis technique, as well as the methods of phylogenetic data processing, are being developed and improved through the complex automation of the experimental part and the involvement of the mathematical apparatus of phylogenetic algorithms. Therefore, the planning of future research in the field of molecular phylogenetics is directly related to the accumulation of information about the nature of the evolution of genome regions studied in phylogenetics.
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Chen, Hai Ying, i Yin Yin Zhou. "An Improved Texture Compression Method for Graphics Hardware". Applied Mechanics and Materials 63-64 (czerwiec 2011): 444–48. http://dx.doi.org/10.4028/www.scientific.net/amm.63-64.444.
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In this paper, we proposed an improved texture compression method for graphics hardware. We first give a detail introduction for the texture compression methods which are popular now. Then, an MIPMap-based texture compression method is proposed that is hybrid compression scheme. For smooth area, we can only use 2Bytes to represent the 4*4 pixels block by bilinear interpolation. Otherwise, we will use iPACKMAN algorithm to deal with the noise areas. Actually, this method is feasible to be implemented by hardware since it is very simple. Experimental results show that our method can achieve high compress ratio and high image quality.
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Roussel, Camille, Alexandre Morel, Michaël Dussiot, Mickael MARIN, Martin Colard, Aurélie Fricot, Anaïs Martinez i in. "Storage-Induced Micro-Erythrocytes Are Rapidly Cleared from Recipient Circulation and Predict Transfusion Recovery". Blood 134, Supplement_1 (13.11.2019): 717. http://dx.doi.org/10.1182/blood-2019-128161.
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Background Hypothermic storage of red blood cell (RBC) concentrates for up to 42 days is associated with biochemical, molecular, morphological, and mechanical modifications. This "storage lesion" increases with storage duration and is associated with increased clearance of transfused storage-damaged RBCs from the recipient's circulation in the first few hours post-transfusion. This rapid clearance reduces transfusion efficacy, but how it occurs is not fully elucidated. RBCs with reduced surface area called "storage-induced micro-erythrocytes" (SMEs) were recently described. Their proportion increases from 2% to 23% during storage. Their reduced surface-to-volume ratio is expected to induce rapid mechanical clearance by the spleen. We aimed to evaluate whether SMEs can be used as a marker of transfusion efficacy, if this subpopulation of RBCs is preferentially cleared by the spleen after transfusion, and if so, by which mechanisms. Methods We evaluated the proportion of SMEs in stored RBC concentrates in vitro using ImageStream and correlated it to the 51Chromium-labeled 24h post-transfusion recovery (24hPTR) in vivo in 31 healthy human volunteers. We then investigated the fate of SMEs during 8 ex vivo perfusions of human spleens (16 RBC concentrates stored for 35-42 days). Finally, we developed a mouse transfusion model to assess the fate of SMEs in vivo and determine their main mechanisms of clearance. Results The proportion of SMEs in RBC concentrates at day 42 of storage correlated negatively with 24hPTR in healthy volunteers (r=-0.42, P<0.01). When perfused ex vivo into human spleens, 15% of stored RBCs (35-42 days of storage) were cleared during the first 40 min of perfusion in a 2-step process: 7% of circulating RBCs disappeared in the first 2 min (1-2 passages through the spleen) while 8% were cleared between 10 and 40 min after initiating perfusion (>5 passages through the spleen). The percentage of SMEs correlated with splenic retention rate ex vivo (r=0.46, p<0.05). Morphological analysis of 6 stored RBC concentrates showed a mean decrease in the proportion of SMEs from 20.2% to 7.8% between the beginning and end of splenic perfusions. In our mouse transfusion model, SMEs accumulated during RBC storage. The 24hPTR also decreased with storage duration (64% on Day 14 vs. 95% on Day 1). The decrease in 24hPTR of long-stored RBCs was mostly due to clearance of the SME subpopulation. SME and morphologically normal long-stored RBC subpopulations displayed clearances of 83% and 13%, respectively. Stored RBCs accumulated predominantly in the spleen post-transfusion, and were mainly ingested by macrophages. In macrophage-depleted mice, 24hPTR improved (from 64% to 79%), splenic accumulation and clearance of SMEs were delayed, and the proportion of inflammatory monocytes increased and mediated clearance. In splenectomized mice, clearance of SMEs was not delayed, but increased accumulation was observed in the liver and bone marrow, and increased erythrophagocytosis by inflammatory monocytes was also observed. Conclusions We show that the proportion of SMEs correlates with 24hPTR in healthy human volunteers and with retention in human spleens perfused ex vivo. In vivo mouse data confirms these findings, showing that SMEs are cleared from the recipient circulation during the 24h following transfusion. Clearance of SMEs is delayed in macrophage-depleted mice, suggesting a central role of macrophages in this process. The human spleen is also likely to clear SMEs from the recipient's circulation, as suggested by experiments with human spleens perfused ex vivo. However, the spleen is not required, because SME clearance is not affected in splenectomized mice. This suggests that other organs may compensate to remove SMEs and highlights the importance of eliminating these morphologically-altered RBCs. Finally, quantification of SMEs is an operator-independent, reproducible marker of transfusion efficacy. It can be used to assess the potential of new processes to prepare and store RBC concentrates. Pre-transfusion quantification of SMEs could benefit chronically transfused patients, for whom improved transfusion efficacy is expected to reduce transfusion-induced iron overload. Disclosures Roussel: Zimmer Biomet: Research Funding. MARIN:Zimmer Biomet: Research Funding. Spitalnik:Hemanext: Membership on an entity's Board of Directors or advisory committees; Tioma, Inc.: Consultancy. Hermine:AB science: Consultancy, Equity Ownership, Honoraria, Research Funding; Celgene: Research Funding; Novartis: Research Funding. Buffet:Zimmer Biomet: Research Funding. Amireault:Zimmer Biomet: Research Funding.
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Zhao, Dawei, Jun Wang, Luo Zuo i Jipeng Wang. "A Novel Cross-Correlation Algorithm Based on the Differential for Target Detection of Passive Radar". Remote Sensing 15, nr 1 (31.12.2022): 224. http://dx.doi.org/10.3390/rs15010224.
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For the problem of traditional passive radar target detection, the cross-correlation method is a popular solution. By processing the reference signal and the target echo signal coherently, the method is able to extract the target parameters, such as distance, velocity, and azimuth. However, the estimation performance is limited by the low signal-to-noise ratio. Therefore, a new cross-correlation algorithm for passive radar target detection is proposed in this paper. The echo signal received by the echo antenna and the reference signal received by the reference antenna are processed by differential operations to transform the single signal into multiple signals. Then, the differential reference signal is used to eliminate the signal phase in the differential echo signal. With the two-dimensional Fourier transform, the coherent accumulation of multiple signals is realized based on matched filtering of the single signal. This makes the secondary accumulation of the target signal coherent, while the interference part can only obtain incoherent secondary accumulation. In this way, the signal-to-noise ratio for target detection can be greatly improved. The paper presents the theoretical derivation of the algorithm and the quantitative analysis of its performance. The results of both simulated and measured data show that the detection performance is greatly improved compared with the traditional method.
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Deleu, S., B. Trindade de Carvalho, I. Jacobs, K. Arnauts, L. Deprez, E. Vissers, M. Lenfant i in. "P079 Attenuation of inflammation and histologic production-dependent improvement by engineered high acetate producing Saccharomyces boulardii in DSS-induced colitis". Journal of Crohn's and Colitis 17, Supplement_1 (30.01.2023): i243—i245. http://dx.doi.org/10.1093/ecco-jcc/jjac190.0209.
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Abstract Background It has been hypothesized that the probiotic potential of the yeast Saccharomyces boulardii (Sb) is associated with its acetate production. This SCFA is of interest in IBD due to its cross-feeding potential with beneficial butyrate-producing bacteria and low toxicity to epithelial cells . Our previous in vitro work supports this hypothesis (Deleu et al, 2022) but still requires in vivo validation. Therefore, we evaluated the effect of different engineered Sb strains producing variable amounts of acetate in DSS-induced colitis in mice. Methods Nine week old female C57/Bl6 mice (N=120) were allocated to 12 treatment groups receiving drinking water or 2.75% DSS in combination with PBS (control), Baker’s yeast (non-probiotic control), SDH1 (non-acetate producing Sb), ENT (transient acetate producing Enterol strain-probiotic control), SbP (high acetate producing Sb) and ENT3 (extra high acetate producing Sb). Disease activity including weight loss, diarrhoea and the presence of occult blood was scored daily. On day 7, the DSS groups were transferred to regular drinking water and on day 14 mice were sacrificed. Colonic tissue and blood were collected for resp. histologic and cytokine analysis. Results Disease activity, determined by the area under the curve, in DSS subgroups was lower for SbP compared to PBS and Baker’s yeast (both p<0.05). Remarkably, Sb SDH1 showed even higher disease activity compared to the Sb strains ENT, SbP and ENT3 (all p<0.05). At sacrifice, macroscopic damage score in DSS subgroups was lower for SbP and ENT3 (both p<0.05) compared to Sb SDH1 and the colon weight/length-ratio was decreased for ENT and SbP compared to Sb SDH1 (resp. p=0.06 and p=0.08). Higher histologic inflammation was noted in the non- or only transient-acetate producing strains on DSS compared to healthy PBS control (all p<0.05), whereas this increase was not observed for both high-acetate producing strains SbP and ENT3 on DSS (p=NS). Lower IL1β, IL2 and IL4 concentrations for DSS groups on SbP and ENT3 compared to DSS groups on Sb SDH1 and ENT were observed (all p<0.05). In contrast, IL10, TNFα and KC/GRO were lower for the DSS groups on Sb SDH1 and ENT compared to DSS groups on SbP, ENT3, and even PBS for IL2 and 4 (all p<0.05). Conclusion Engineered high acetate producing Sb strains show a significant trend towards improved attenuation of DSS-induced colitis compared to the parent Sb strain on disease activity, macroscopic damage score and show production-dependent response on histology. Mixed pro-inflammatory serum profiles were observed potentially pointing in the direction of other effects of acetate accumulation. Together with our previous in vitro work, these data indicate a role for Sb-produced acetate in attenuating inflammation.
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Wan, M., Y. Guo, S. Li i T. Liu. "METHOD OF IMPROVED TDICCD DESIGN BASED ON SENSOR CLOCKING". ISPRS Annals of Photogrammetry, Remote Sensing and Spatial Information Sciences V-3-2020 (3.08.2020): 689–93. http://dx.doi.org/10.5194/isprs-annals-v-3-2020-689-2020.
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Abstract. The final output signal quality of TDICCD is related to the key parameters such as working mode, output mode, signal-to-noise ratio, dynamic range and so on. We can improve these parameters of TDICCD by reasonably designing the sensor clocking. Therefore, this text discussed four methods of improved TDICCD sensor clocking to solve some problem in TDICCD application based on using the principle of TDICCD. The technique of TDICCD Taps merging can reduce the number of TDICCD Taps, which helps to reduce the size of the TDICCD rear-end circuit significantly; The technique of TDICCD continuous transfer clocking can improve the charge transfer efficiency, which helps to promote the final signal-to-noise ratio; The technique of pixel binning clocking can enlarge the dynamic range of image; The technique of TDICCD area-array working mode can extend the field of TDICCD working; The principle, derivation process, clocking sequence diagram and application range of these clocking design schemes are given in this paper. At the same time, it also explains its actual effect and the matters to be noted.
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Pelto, Mauri S. "The Annual Balance of North Cascade Glaciers, Washington, U.S.A., Measured and Predicted Using An Activity-Index Method". Journal of Glaciology 34, nr 117 (1988): 194–99. http://dx.doi.org/10.1017/s0022143000032238.
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AbstractThe annual balance has been measured for ten North Cascade glaciers in 1983–84, 1984–85, 1985–86, and 1986–87 (1984, 1985, 1986, and 1987). Based on these data, an annual balance prediction method was designed and tested. Comparison of measured versus predicted annual balances indicates an accuracy of ±0.22–0.30 m. The method is based on annual measurement of the accumulation area ratio (AAR), and determination of the perennially constant activity index and area-altitude distribution on each glacier. The accumulation area ratio is determined from aerial and ground photographs at the end of the ablation season. The activity index is identified from observation of the rise of the snow line with time, compared to measured snow depths above the snow line. The AAR-activity index method was used to calculate the annual balance of 47 North Cascade glaciers in 1984, 1985, 1986, and 1987. The mean balance during the 4 year period was —0.33 m.From the mass-balance records, it is apparent that North Cascade glaciers can be divided into six climatic sensitivity groups. Each glacier type responds differently to specific climatic conditions. The mass-balance variation for glaciers of the same type is small.Since 1977, warmer, drier climatic conditions have prevailed in the North Cascades, resulting in the retreat of 42 of the 47 glaciers examined.
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Pelto, Mauri S. "The Annual Balance of North Cascade Glaciers, Washington, U.S.A., Measured and Predicted Using An Activity-Index Method". Journal of Glaciology 34, nr 117 (1988): 194–99. http://dx.doi.org/10.3189/s0022143000032238.
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AbstractThe annual balance has been measured for ten North Cascade glaciers in 1983–84, 1984–85, 1985–86, and 1986–87 (1984, 1985, 1986, and 1987). Based on these data, an annual balance prediction method was designed and tested. Comparison of measured versus predicted annual balances indicates an accuracy of ±0.22–0.30 m. The method is based on annual measurement of the accumulation area ratio (AAR), and determination of the perennially constant activity index and area-altitude distribution on each glacier. The accumulation area ratio is determined from aerial and ground photographs at the end of the ablation season. The activity index is identified from observation of the rise of the snow line with time, compared to measured snow depths above the snow line. The AAR-activity index method was used to calculate the annual balance of 47 North Cascade glaciers in 1984, 1985, 1986, and 1987. The mean balance during the 4 year period was —0.33 m.From the mass-balance records, it is apparent that North Cascade glaciers can be divided into six climatic sensitivity groups. Each glacier type responds differently to specific climatic conditions. The mass-balance variation for glaciers of the same type is small.Since 1977, warmer, drier climatic conditions have prevailed in the North Cascades, resulting in the retreat of 42 of the 47 glaciers examined.
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Mukhopadhyay, Biswajit, i Asif Khan. "Altitudinal variations of temperature, equilibrium line altitude, and accumulation-area ratio in Upper Indus Basin". Hydrology Research 48, nr 1 (1.02.2016): 214–30. http://dx.doi.org/10.2166/nh.2016.144.
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Quantitative measures of adiabatic lapse rate, equilibrium line altitude (ELA), and accumulation-area ratio (AAR) are important to understand the hydrological processes and conduct hydrological modeling in a highly glaciated watershed. We present a detailed analysis of temperature data from 21 climatic stations, hypsometric analyses of glacier distributions, and a method to analyze ablation gradients and runoff curves concurrently to quantify these parameters for the watersheds of the Upper Indus Basin (UIB), with 15,062 km2 of glacierized area and an elevation range of 361–8,611 m. We show that the ELA varies considerably from one watershed to another, implying a highly variable upper elevation limit up to which melting of snows and glaciers takes place throughout the basin. This is in sharp contrast to the assertions made by previous researchers. We show that the ELA is as low as 4,840 m in Astore watershed and it is as high as 6,200 m in Shyok watershed. In accordance with the variation of ELA, the AAR also varies considerably from one watershed to another. It is as low as 0.10 in Gilgit and as high as 0.65 in Zanskar watersheds. We ascribe 15–20% uncertainty to these estimates of ELA and AAR in UIB.
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Kircher, Moritz F., Lee Josephson i Ralph Weissleder. "Ratio Imaging of Enzyme Activity Using Dual Wavelength Optical Reporters". Molecular Imaging 1, nr 2 (1.04.2002): 153535002002011. http://dx.doi.org/10.1162/15353500200201124.
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The design of near-infrared fluorescent (NIRF) probes that are activated by specific proteases has, for the first time, allowed enzyme activity to be imaged in vivo. In the current study, we report on a method of imaging enzyme activity using two fluorescent probes that, together, provide improved quantitation of enzymatic activity. The method employs two chemically similar probes that differ in their degradability by cathepsin B. One probe consists of the NIRF dye Cy5.5 attached to a particulate carrier, a crosslinked iron oxide nanoparticle (CLIO), through cathepsin B cleavable l-arginyl peptides. A second probe consists of Cy3.5 attached to a CLIO through proteolytically resistant d-arginyl peptides. Using mixtures of the two probes, we have shown that the ratio of Cy5.5 to Cy3.5 fluorescence can be used to determine levels of cathepsin B in the environment of nanoparticles with macrophages in suspension. After intravenous injection, tissue fluorescence from the nondegradable Cy3.5–d-arginyl probe reflected nanoparticle accumulation, while fluorescence of the Cy5.5–l-arginyl probe was dependent on both accumulation and activation by cathepsin B. Dual wavelength ratio imaging can be used for the quantitative imaging of a variety of enzymes in clinically important settings, while the magnetic properties of the probes allow their detection by MR imaging.
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Wang, Fang, Yang Chao, Ming Han Xu, Rui Hua Wang, Ai Xia Chen, Ru Xin Deng, Du Juan Chang, Jie Guang Song i Yue Ning Qin. "Preparation of Tin Oxide Nanometer Thin Films by Hydrothermal Method". Solid State Phenomena 279 (sierpień 2018): 197–201. http://dx.doi.org/10.4028/www.scientific.net/ssp.279.197.
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Given the shortage of energy reserves, new energy sources must be identified. In this regard, improving the efficiency of solar cell conversion and simplifying the solar cell technology have become the focus of research. In this study, tin oxide nanometer thin film was fabricated on FTO conductive glass as photocathode through hydrothermal method. The synthesis condition was regulated, and performance test was also conducted. Results show that the crystallization driving force, crystallization rate, and grain size of tin dioxide crystal increase with increasing alkali ratio, leading to disorganized accumulation of tin oxide. Under prolonged holding time, tin oxide crystal became complete, and the surface area of the crystal increased. The crystallization driving force and rate also increased with increasing salt concentration and accompanied by clutter of tin oxide. The optimized process condition included 1:4 molar ratio of salt to alkali, 0.05 mol/L salt concentration, 200 °C reaction temperature, and 8 days of reaction. The highest specific surface area of the tin oxide nanometer film was obtained under the optimized condition.
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Xi, Jian Hui, i Jia Chen. "An Improved Noise Reduction Based on Wavelet Threshold". Key Engineering Materials 474-476 (kwiecień 2011): 1701–5. http://dx.doi.org/10.4028/www.scientific.net/kem.474-476.1701.
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Based on multi-resolution analysis of wavelet, this article is aimed at building a new soft threshold function for wavelet de-noising, to overcome the discontinuous disadvantage of the hard threshold function. In the area adjacent to the threshold, continuously adjustable nonlinear functions are introduced in piecewise to process the wavelet coefficients more carefully in this area. Consequently, large deviation caused by super-compression of wavelet coefficients when using traditional soft threshold could be avoided, and the nonlinearity of the system is able to be effectively kept. Using both signal to noise ratio (SNR) and mean square error (MSE) as the evaluation indicators, simulation results show that the improved method is more effective than the method based on traditional hard and soft threshold.
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Faria, O. A. C., T. S. Kawamoto, L. R. O. Dias, A. A. G. Fidelis, L. O. Leme, J. F. W. Sprícigo i M. A. N. Dode. "200 Maturation method affects lipid accumulation in bovine oocytes". Reproduction, Fertility and Development 32, nr 2 (2020): 228. http://dx.doi.org/10.1071/rdv32n2ab200.
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Invitro maturation is a key step in invitro embryo production, since its success will depend on the availability of good quality oocytes. Previous studies have shown that it is during this stage that the greatest accumulation of lipid droplets occurs, which is reflected in the amount of lipid present in embryos produced invitro. However, this is not observed when maturation is performed invivo. Therefore, we hypothesised that lipid accumulation would be avoided if oocyte maturation were carried out in ovarian follicles following intrafollicular transfer of immature oocytes (IFIOT). We compared lipid accumulation in oocytes matured invitro, invivo, and by IFIOT. A total of 90 Nellore heifers were distributed in 3 experimental groups: donors of immature oocytes (D-IMA), ovulators of IFIOT oocytes (D-OV), and superstimulated donors of invivo-matured oocytes (D-FSH). All animals rotated through all groups during the experiment. To obtain immature oocytes, the D-IMA were submitted to ovum pickup (OPU), in which aspiration medium was supplemented with 500μM 3-isobutyl-1-methylxanthine (IBMX), and, after selection, part of the oocytes were cultured invitro for 22h (MatF) and part were used for IFIOT (MatT). To perform MatT, the D-OV had their ovulation synchronized by a progesterone and benzoate oestradiol protocol, in which 30h after the implant removal, the IFIOT was performed on the dominant follicle. The D-FSH oocytes were stimulated with 80mg of FSH (Folltropin; Vetoquinol) over 4 days, every 12h, in decreasing doses. At the same time that the immature oocytes were placed in MatF and IFIOT, ovulation was induced with the gonadotrophin releasing hormone (GnRH) analogue (50µg of lecirelin) in D-OV and D-FSH groups. After 22h, matured oocytes were either removed from culture (MatF) or recovered from follicles by OPU (MatT and MatS). From the recovered oocytes of all groups, only those with a polar body were used for lipid droplet evaluation. To quantify lipid accumulation, denuded oocytes were fixed and stained with boron-dipyrromethene (Bodipy) 493/503 (20 µgmL−1) and evaluated by confocal microscopy. Captured images were evaluated in the ImageJ program (National Institutes of Health), and lipid content was determined by calculating the ratio of the area of the lipid droplets to total oocyte area. Data were analysed by ANOVA with statistical significance set at P<0.05. A total of 95 oocytes were evaluated: 25 immature (CT), 24 invitro (MatF), 30 invivo (MatS), and 16 invivo (MatT). The mean area containing lipid droplets in immature oocytes (14%±0.9) was similar (P>0.05) to that observed in both invivo maturation systems (MatS=17.26%±0.8 and MatT=14.11%±0.9). However, in the MatF oocytes, lipid content (24.34%±1) increased during maturation and was higher than in the other groups (P<0.05). We showed for the first time that oocytes matured by IFIOT are similar to those invivo matured with regard to lipid content, which may imply their superior quality over those matured invitro. This new maturation method opens new possibilities for biotechnologies that need to use mature oocytes, such invitro embryo production, oocyte and embryo cryopreservation, cloning, and transgenesis. This study was supported by FAP-DF and Capes.
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Liu, Ya Jie, Yan Zhao i Fa Lin Wu. "An Improved Geomagnetic Matching Algorithm Using Rotation Angle Search Technique". Advanced Materials Research 383-390 (listopad 2011): 7576–81. http://dx.doi.org/10.4028/www.scientific.net/amr.383-390.7576.
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The accumulation course angle error of inertial navigation system will decrease the accuracy and reliability of an geomagnetism aided inertial navigation system using a geomagnetic contour matching algorithm. To improve the matching accuracy, the matching track and true track should be as parallel as possible. An improved geomagnetic matching algorithm is presented by introducing rotation angle search technique. To reduce the computation burden, improve operation efficiency and reduce false matching probability, a new search area determination method is proposed, which redefines the search region and reduces the search range. Simulation results demonstrate the effectiveness of the proposed algorithm and the improvement in the matching accuracy.
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Fan, Xiangsuo, Zhiyong Xu, Jianlin Zhang, Yongmei Huang i Zhenming Peng. "Infrared Dim and Small Targets Detection Method Based on Local Energy Center of Sequential Image". Mathematical Problems in Engineering 2017 (2017): 1–16. http://dx.doi.org/10.1155/2017/4572147.
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In order to detect infrared (IR) dim and small targets in a strong clutter background, a method based on local energy center of sequential image is proposed. This paper began by using improved anisotropy for background prediction (IABP), followed by target enhancement by improved high-order cumulates (HOC). Finally, on the basis of image preprocessing, the paper constructs a sequential image energy center detection algorithm that integrates the neighborhood, continuity, area, and energy and other motion characteristics of the target. Experiments showed that the improved anisotropic background predication could be loyal to the true background of the original image to the maximum extent, presenting a superior overall performance to other background prediction methods; the improved HOC significantly increased the signal-noise ratio of images; when the signal-noise ratio (SNR) is lower than 2.5 dB, the proposed method could effectively eliminate noise and detect targets.
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Liu, Li Yan, Rong Fu, Yi He i Ying Qian Zhang. "Deployment Strategy in Distributed Underwater Sensor Networks". Applied Mechanics and Materials 602-605 (sierpień 2014): 3643–47. http://dx.doi.org/10.4028/www.scientific.net/amm.602-605.3643.
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Distributed underwater sensor network coverage is divided into two main categories: deterministic coverage and stochastic coverage. A strategy is put forward to deploy determinate area by using a triangular-grid method. When a coverage ratio is known, the distance between nodes can be adjusted to meet the coverage ratio in the monitored area, and the least number of sensor nodes can be calculated. Also a heuristic method is proposed for stochastic area deployment strategy. It is under the premise that the initial node location randomly deployed is given, using Voronoi diagram, the not easiest monitored path is searched, and the network coverage performance is improved by configuring the new nodes in the path. Finally it is proved that network performance is more improved by the simulation experiments, when one to four nodes are configured in the easiest breach path.
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Dai, Yan, Dan Liu, Qingrong Hu i Xiaoli Yu. "Radar Target Detection Algorithm Using Convolutional Neural Network to Process Graphically Expressed Range Time Series Signals". Sensors 22, nr 18 (11.09.2022): 6868. http://dx.doi.org/10.3390/s22186868.
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Under the condition of low signal-to-noise ratio, the target detection performance of radar decreases, which seriously affects the tracking and recognition for the long-range small targets. To solve it, this paper proposes a target detection algorithm using convolutional neural network to process graphically expressed range time series signals. First, the two-dimensional echo signal was processed graphically. Second, the graphical echo signal was detected by the improved convolutional neural network. The simulation results under the condition of low signal-to-noise ratio show that, compared with the multi-pulse accumulation detection method, the detection method based on convolutional neural network proposed in this paper has a higher target detection probability, which reflects the effectiveness of the method proposed in this paper.
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Zhang, Yi, i Jinli Huang. "Structure of the Sediment and Crust in the Northeast North China Craton from Improved Sequential H-k Stacking Method". Open Geosciences 11, nr 1 (26.10.2019): 682–96. http://dx.doi.org/10.1515/geo-2019-0054.
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Abstract H-k stacking method is a standard receiver-function method to detect crustal thickness. But this method can not be applied in low-velocity sedimentary basins. To solve this problem, we propose an improved sequential H-k stacking method. The improved method needs two sequential stacks. Firstly, sediment structure is calculated using converted waves and multiples on the bottom boundary of sediments. Secondly, the sedimentary results are applied to calculate the crustal structure. Theoretical calculations and “recovery tests” indicate that the improved method can obtain accurate estimates in sedimentary basins. With the teleseismic data of North China Craton, the structure of sediments is thick in the depression and thin in the uplifted area, which is consistent with Deep Seismic Sounding results. The crust to the west of the North-South Gravity Lineament is relatively thick and has a low average Poisson ratio, whereas the east is relatively thin and has a high average Poisson ratio. This result and the structural feature from data regression imply that the eastern crust of the North China Craton has experienced wide extension, which reflect the crustal response to the severe destruction and deformation in that area compared to the western crust.
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Zhang, Yiyi, Keshuo Shi, Chunyan Zang, Wenchang Wei, Chuanhui Xu i Junwei Zha. "Improved Insulation Properties of Polypropylenes in HVDC Cables Using Aqueous Suspension Grafting". Materials 15, nr 18 (10.09.2022): 6298. http://dx.doi.org/10.3390/ma15186298.
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Owing to its lack of crosslinking, polypropylene (PP) is considered an environmentally friendly alternative to crosslinked polyethylene as high-voltage direct current (HVDC) cable insulation. However, pure PP can accumulate space charges under a HVDC, and thus must be modified for use as an insulating material for HVDC cables. In this study, 4-methylstyrene is grafted onto PP using an aqueous suspension grafting method to improve its properties. The effects of the swelling time, reaction time, and 4-methylphenylene concentration on the reaction were investigated. The optimum process conditions were determined, including an optimum grafting ratio of 0.97%. The volume resistivity, ability to suppress space-charge accumulation, and DC breakdown strength of modified PP were also studied. Modified PP with a grafting ratio of 0.88% showed optimal space-charge suppression and the highest volume resistivity and breakdown strength. The work will facilitate the design and development of more efficient insulation materials for HVDC cables.
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Qin, Hongde, Lingyu Li, Peng Li i Xiangqian Wang. "Hydrodynamic performance optimization and experimental verification of underwater glider based on parametric method". Science Progress 105, nr 4 (październik 2022): 003685042211313. http://dx.doi.org/10.1177/00368504221131380.
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In this paper, the wing body fusion method is used to complete the design of underwater glider. On this basis, the traditional optimization algorithm of underwater gliding wing shape is improved. Based on the improved Hicks Henne algorithm and genetic algorithm, the shape optimization of underwater glider is completed. Through the further optimization of the overall performance, the overall shape of the glider is improved and the maximum lift drag ratio is increased. Finally, the physical experiment of the optimized shape is carried out according to the experimental water area of the circulating water tank. Through the comparative analysis of the data, the accuracy of the numerical calculation is verified.
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Wang, Yanjun, Gang Li, Wenjuan Yan, Guoquan He i Ling Lin. "Heterogeneity Detection Method for Transmission Multispectral Imaging Based on Contour and Spectral Features". Sensors 19, nr 24 (5.12.2019): 5369. http://dx.doi.org/10.3390/s19245369.
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Transmission multispectral imaging (TMI) has potential value for medical applications, such as early screening for breast cancer. However, because biological tissue has strong scattering and absorption characteristics, the heterogeneity detection capability of TMI is poor. Many techniques, such as frame accumulation and shape function signal modulation/demodulation techniques, can improve detection accuracy. In this work, we develop a heterogeneity detection method by combining the contour features and spectral features of TMI. Firstly, the acquisition experiment of the phantom multispectral images was designed. Secondly, the signal-to-noise ratio (SNR) and grayscale level were improved by combining frame accumulation with shape function signal modulation and demodulation techniques. Then, an image exponential downsampling pyramid and Laplace operator were used to roughly extract and fuse the contours of all heterogeneities in images produced by a variety of wavelengths. Finally, we used the hypothesis of invariant parameters to do heterogeneity classification. Experimental results show that these invariant parameters can effectively distinguish heterogeneities with various thicknesses. Moreover, this method may provide a reference for heterogeneity detection in TMI.
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Zhao, Gaofeng, Hao Zheng, Yingying Li, Kehui Zhu i Jianfeng Li. "A Frequency Domain Direct Localization Method Based on Distributed Antenna Sensing". Wireless Communications and Mobile Computing 2021 (1.06.2021): 1–10. http://dx.doi.org/10.1155/2021/6616729.
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Traditional two-step passive localization methods need to extract the parameters like the direction of arrival (DOA), time of arrival (TOA), and time difference of arrival (TDOA) from the original data to determine the source position, which causes the poor positioning accuracy due to error accumulation. In this paper, a direct position determination (DPD) method is proposed to improve the positioning accuracy and robustness, which is based on a correlation algorithm. Firstly, the cost function directly related to the location of the source can be established by synthesizing the data received by multiantenna in the frequency domain. Then, the position of the source is estimated by the correlation DPD method to search the monitoring area. Compared to the improved TDOA algorithm and Least Squares DPD algorithm, the proposed method shows better localization accuracy of different SNRs. Finally, based on real measured data, it can be seen that the results of the proposed algorithm are better than the improved TDOA algorithm.
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von Windheim, Jesko A., i Jeffrey T. Glass. "Improved uniformity and selected area deposition of diamond by the oxy-acetylene flame method". Journal of Materials Research 7, nr 8 (sierpień 1992): 2144–50. http://dx.doi.org/10.1557/jmr.1992.2144.
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The role of SiO2 in nucleation of diamond has been investigated in an oxy-acetylene flame. It was found that growth methods that minimize SiO2 formation enhance diamond nucleation. A short pretreatment of a scratched Si surface in a low oxygen-to-acetylene ratio flame, at a distance 1.5 cm from the flame core, significantly improved uniformity of subsequent diamond growth. When scratched surfaces were intentionally oxidized, nucleation of diamond was completely inhibited. By using a mask to controllably deposit SiO2 on a scratched Si surface, highly selective deposition of diamond was achieved with resolution below 5 μm. These results are discussed with reference to competing oxidation and carbon formation processes that take place during the nucleation of diamond. During the nucleation stage, carbon may be deposited on the scratched Si via a route in which the Si surface catalyzes carbon formation reactions that are otherwise kinetically unfavorable. The formation of an oxide layer, on the other hand, would act to passivate the surface, and thus inhibit carbon formation via a catalytic route. The decomposition of CO to C and CO2 is given as an example of a reaction that is favored at temperatures below 1000 K, but requires surface catalysis to proceed because it remains frozen out in the gas phase due to a very slow reaction rate.