Journal articles on the topic 'Interference fit estimation'
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Bonisoli, Elvio, Gabriele Marcuccio, and Simone Venturini. "Interference fit estimation through stress-stiffening effect on dynamics." Mechanical Systems and Signal Processing 160 (November 2021): 107919. http://dx.doi.org/10.1016/j.ymssp.2021.107919.
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Wang, Xingyuan, Zhifeng Lou, Xiaodong Wang, Xiupeng Hao, and Yue Wang. "Prediction of stress distribution in press-fit process of interference fit with a new theoretical model." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 233, no. 8 (September 7, 2018): 2834–46. http://dx.doi.org/10.1177/0954406218799783.
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Interference fit is widely used in many industrial fields for its high ability to transmit an axial force or torque between a shaft and hub. But the performance of interference fits during their life in service is limited by stress concentrations and surface wear. Nowadays, theoretical methods based on thick-walled cylinder theory become increasingly abundant. However, the prediction results of stress distribution in press-fit process are not accurate for ignoring the stress concentrations. Since the stress distribution is significant for analysis of surface wear and assembly quality, especially for precision assembly of small parts, the purpose of this study is to build a new theoretical model to predict the stress distribution. The stress distribution equation was deduced based on a simplified model that a nonuniform linear load acts on a portion of semi-infinite plane. Finally, the stress distribution in the press-fit process was analyzed by the theoretical model, as well as the stress distribution of different material pairs (Ni36CrTiAl–50Ni-50Fe, AISI 1045–AISI 1045) under full contact condition. The comparison between theoretical and numerical results shows that the new theoretical model has high accuracy in predicting stress distribution and maximum stress, and the relative error is less than 17%. Therefore, the new theoretical model can give more reasonable results and provide a more reliable approach for design of interference fits. Furthermore, the model provides a method for the optimization of interference analysis under different structures and working conditions, and gives a theoretical basis for real-time estimation of assembly quality.
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Fellows, Gary M., and Fred W. Roeth. "Shattercane (Sorghum bicolor) Interference in Soybean (Glycine max)." Weed Science 40, no. 1 (March 1992): 68–73. http://dx.doi.org/10.1017/s0043174500056976.
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Shattercane interference in irrigated soybean was evaluated during 1987, 1988, and 1989 at Clay Center, NE, using ‘Rox’ forage sorghum to simulate shattercane. Soybean yield reduction did not occur if shattercane was removed by 2 wk after emergence in 1987 and 6 wk after emergence in 1988 and 1989. Shattercane interference with soybean began when shattercane height exceeded soybean height. Soybean yield was reduced up to 25% before the height differential reached 30 cm, the minimum difference required for selectively applying glyphosate with a wiper applicator. Soybean nodes per stem, pods per stem, and beans per pod decreased as duration of interference increased. A direct relationship between soybean yield loss and shattercane density fit a rectangular hyperbolic function. Yield loss per shattercane plant was highest at low shattercane densities. Soybean plant height, biomass, nodes per stem, pods per stem, pods per node, and beans per pod decreased as shattercane density increased. An interference model for estimation of soybean yield and economic loss based on shattercane density was developed.
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Nakata, Rie, David Lumley, Gary Hampson, Kurt Nihei, and Nori Nakata. "Waveform-based estimation of Q and scattering properties for zero-offset vertical seismic profile data." GEOPHYSICS 85, no. 4 (May 14, 2020): R365—R379. http://dx.doi.org/10.1190/geo2019-0369.1.
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Estimating [Formula: see text] using downgoing waves in zero-offset vertical seismic profiles (VSPs) can be challenging when scattered waves from near-borehole heterogeneities interfere with direct arrivals. In any [Formula: see text] estimation method that assumes a downgoing plane wave, constructive and destructive wave-mode interference can cause errors in the estimate. For example, in the spectral-ratio method, such interference modulates the amplitude spectra introducing significant variations and even nonphysical negative [Formula: see text] (amplification) estimates. We have investigated this phenomenon using synthetic and field data sets from offshore Australia and developed a two-step waveform-based method to characterize scattering anomalies and improve [Formula: see text] estimates. Waveform information is key to deal with closely spaced band-limited seismic events. First, we solve an inverse problem to locate and characterize scatterers by minimizing the traveltime and waveform misfits. Then, using the estimated parameters, we model the scatterers’ contribution to the VSP data and remove it from the observed waveforms. The resulting spectra resemble those that would have been acquired in the absence of the scatterers and are much more suitable for the spectral-ratio method. By assuming a 1D medium and a simple scatterer shape (i.e., circular), we parameterize a scattering heterogeneity using five parameters (depth, distance, size, velocity, and density) and seek a solution using a grid search to handle the nonuniqueness of the VSP inversion. Instead, adaptive subtraction is required to fine-tune the modeled interference to better fit the observation. We successfully use this method to characterize and mitigate the strongest wave interference in the field data. The final [Formula: see text] estimates contain milder variations and much less nonphysical negative [Formula: see text]. Our results demonstrate that the proposed method, readily extendible to multiple scatterer cases, can locate discrete scatterers, remove the effects of their interference, and thus significantly improve the [Formula: see text] estimates from VSP data.
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Che, Hao, An Li, Jie Fang, Xi Chen, and Fang-Jun Qin. "Interference fringe fitting of atom gravimeter based on fitness particle swarm optimization." AIP Advances 12, no. 7 (July 1, 2022): 075211. http://dx.doi.org/10.1063/5.0096967.
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In the atom gravimeter, three Raman pulses are utilized to realize the interference of atom matter waves, and atom interference fringes are obtained by scanning the chirp rate of the Raman laser during the interference time. Previously, fringe data analysis methods used LS (Least Squares) to fit the cosine function of each interference fringe data to minimize the standard deviation between the estimated value and the observed value of each group of fringe data or the EKF (Extended Kalman Filter) method to obtain the estimation of the gravity value. In this paper, we propose a new method applied to the interference fringe fitting of the atom gravimeter, namely, through the FPSO (Fitness Particle Swarm Optimization) method to estimate the parameters of the interference fringe atom and then estimate the gravity value. First, the theoretical analysis and proof are carried out by using simulation data. On this basis, we carried out a gravity measurement experiment in the ship-mounted mooring state, which further verified the feasibility and effectiveness of the algorithm. The simulation and experimental results show that, compared with LS and EKF methods, the FPSO method can search the relatively optimal fitting parameters of atom interference fringes quickly and accurately and improve the accuracy and stability of the atom gravimeter measurement. It is feasible and effective to apply the FPSO method to fitting atom interference fringes. The FPSO method proposed in this paper can be used as a new method for fitting atom interference fringes, which provides a new idea and choice for accurate gravity measurement in a dynamic environment.
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Singh, M., M. C. Saxena, B. E. Abu-Irmaileh, S. A. Al-Thahabi, and N. I. Haddad. "Estimation of Critical Period of Weed Control." Weed Science 44, no. 2 (June 1996): 273–83. http://dx.doi.org/10.1017/s0043174500093899.
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An estimation of the critical period of weed control is helpful in formulating appropriate weed-control strategies. A regression approach is presented to estimate the thresholds of critical period of weed control and time of equal interference (or time of onset of competition). In this approach, yields were either a linear or logistic function of the duration of weed-free and weed-infested periods. Confidence intervals of the thresholds of critical period and time of equal interference were determined for the linear model. An approximation to the standard error of critical period and associated confidence interval were given for any general form of the model. The method was applied to estimate the critical period of weed control in rainfed lentil using data from four field experiments conducted in Jordan. The relationship of yield with the duration of weed-free period was described by a linear function, whereas the relationship with the duration of weed-infested period showed a better fit with a logistic function. To maintain 90% of maximum seed yield, the maximum time allowed to let weeds grow after the crop emergence varied over locations from 4.8 to 5.8 wk. The same level could be achieved if the crop is kept free of weeds from its emergence until 12.1 to 14.1 wk; while the time when the same amount of yield would be achieved under both approaches varied from 7.7 to 9.3 wk after crop emergence. For straw yield, the time to get 90% of the maximum yield could vary over location from a maximum of 4.5 to 8.0 wk under weed-infestation and from at least 11.5 to 13.5 wk when weed-free. The time to achieve the same amount of straw under two systems of competition varied from 6.5 to 9.9 wk after crop emergence. One of the four experiments showed a longer critical period than the others for seed and straw yields.
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Musovic, Jasmin, Adriana Lipovac, and Vlatko Lipovac. "BER Aided Energy and Spectral Efficiency Estimation in a Heterogeneous Network." Computation 10, no. 9 (September 16, 2022): 162. http://dx.doi.org/10.3390/computation10090162.
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In this work, we adopt the analysis of a heterogeneous cellular network by means of stochastic geometry, to estimate energy and spectral network efficiency. More specifically, it has been the widely spread experience that practical field assessment of the Signal-to-Noise and Interference Ratio (SINR), being the key physical-layer performance indicator, involves quite sophisticated test instrumentation that is not always available outside the lab environment. So, in this regard, we present here a simpler test model coming out of the much easier-to-measure Bit Error Rate (BER), as the latter can deteriorate due to various impairments regarded here as equivalent with additive white Gaussian noise (AWGN) abstracting (in terms of equal BER degradation) any actual non-AWGN impairment. We validated the derived analytical model for heterogeneous two-tier networks by means of an ns3 simulator, as it provided the test results that fit well to the analytically estimated corresponding ones, both indicating that small cells enable better energy and spectral efficiencies than the larger-cell networks.
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Syme, Neil R., Kathryn Stevens, Catherine Stirling, Donald C. McMillan, and Dinesh Talwar. "Clinical and Analytical Impact of Moving from Jaffe to Enzymatic Serum Creatinine Methodology." Journal of Applied Laboratory Medicine 5, no. 4 (April 3, 2020): 631–42. http://dx.doi.org/10.1093/jalm/jfaa053.
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Abstract Background Identification and monitoring of chronic kidney disease (CKD) requires accurate quantification of serum creatinine. The poor specificity of Jaffe creatinine methods is well documented, and guidelines recommend enzymatic methodology. We describe our experience of moving from Jaffe to enzymatic creatinine methodology. We present comparison of >5000 paired Jaffe and enzymatic creatinine results, examine interferences, and attempt to assess clinical consequences of changing methodology. Methods Overall, 5303 serum samples received for routine creatinine measurement were analyzed using Jaffe and enzymatic methods with an Abbott Architect autoanalyzer. Associated results for glucose, total bilirubin, triglycerides, total protein, and hemolytic, icteric, and lipemic indexes were extracted from the laboratory database. CKD staging was estimated for each sample to assess potential clinical effects. Results The methods correlated well (r = 0.996) and showed good agreement (Passing-Bablok fit, y = 0.935x + 0.074). Paired analysis, however, showed significant differences (P < 0.001), and approximately 20% of results differed by more than ±10%. Multivariate analysis demonstrated independent associations between difference in creatinine results, glucose (P < 0.0001), and hemolytic index (P = 0.009). Glucose demonstrated positive interference in the Jaffe method, and hemolysis produced negative interference in the enzymatic method. Little or no association was observed with other analytes. CKD staging differed in 4% of samples. Conclusions Differences between Jaffe and enzymatic serum creatinine results exceed the recommended 5% target for a significant proportion of samples, particularly at concentrations <1.13 mg/dL (100 µmol/L). Both glucose and hemolysis contribute to the variance in results. Although the clinical impact of these differences seems small, laboratories should continue moving toward enzymatic creatinine estimation to ensure the best estimate of renal function.
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Zhou, Jianguo, Liyuan Ren, and Zhiliang Liu. "Instantaneous lift-off distance estimation in magnetic flux leakage testing of steel wire ropes." Journal of Physics: Conference Series 2184, no. 1 (March 1, 2022): 012051. http://dx.doi.org/10.1088/1742-6596/2184/1/012051.
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Abstract Steel wire rope (SWR) defects plagued its application in many important fields, such as cranes, ports, etc. However, the accuracy of SWRs’ local flaws detection based on magnetic flux leakage (MFL) method is susceptible to the lift-off distance. This paper proposes an instantaneous lift-off distance estimation method to study the effect of lift-off distance on MFL detection for SWR. We firstly derive the relation between the lift-off distance and the MFL field strength based on the magnetic dipole model. After obtaining the time-frequency representation of the MFL signal by using multi-synchrosqueezing transform, we extract the instantaneous amplitude (IA) of the strand signal without other noise interference. Finally, the nonlinear least-squares method is used to fit the relation between the IAs of the strand signals and the lift-off distances to achieve the estimation of the instantaneous lift-off distance. A SWR with three local flaws is tested to validate the proposed method. This work provides instantaneous monitoring of lift-off distances, and it can be used in future noise suppressing methods development or quantitative analysis of local flaws.
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Ye, WenFang, Chuang Qian, Jian Tang, Hui Liu, XiaoYun Fan, Xinlian Liang, and HongJuan Zhang. "Improved 3D Stem Mapping Method and Elliptic Hypothesis-Based DBH Estimation from Terrestrial Laser Scanning Data." Remote Sensing 12, no. 3 (January 21, 2020): 352. http://dx.doi.org/10.3390/rs12030352.
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The detailed structure information under the forest canopy is important for forestry surveying. As a high-precision environmental sensing and measurement method, terrestrial laser scanning (TLS) is widely used in high-precision forestry surveying. In TLS-based forestry surveys, stem-mapping, which is focused on detecting and extracting trunks, is one of the core data processing tasks and the basis for the subsequent calculation of tree attributes; one of the most basic attributes is the diameter at breast height (DBH). This article explores and improves the methods for stem mapping and DBH estimation from TLS data. Firstly, an improved 3D stem mapping algorithm considering the growth direction in random sample consistency (RANSAC) cylinder fitting is proposed to extract and fit the individual tree point cloud section. It constructs the hierarchical optimum cylinder of the trunk and introduces the growth direction into the establishment of the backbone buffer in the next layer. Experimental results show that it can effectively remove most of the branches and reduce the interference of the branches to the discrimination of trunks and improve the integrity of stem extraction by about 36%. Secondly, a robust least squares ellipse fitting method based on the elliptic hypothesis is proposed for DBH estimation. Experimental results show that the DBH estimation accuracy of the proposed estimation method is improved compared with other methods. The mean root mean squared error (RMSE) of the proposed estimation method is 1.14 cm, compared with other methods with a mean RMSE of 1.70, 2.03, and 2.14 cm. The mean relative accuracy of the proposed estimation method is 95.2%, compared with other methods with a mean relative accuracy of 92.9%, 91.9%, and 90.9%.
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Avarmaa, Katri, Lassi Klemettinen, Hugh O’Brien, Ari Jokilaakso, Daniel Lindberg, and Pekka Taskinen. "Solubility of Palladium in Alumina-Iron Silicate Melts." JOM 73, no. 6 (April 23, 2021): 1871–77. http://dx.doi.org/10.1007/s11837-021-04672-4.
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AbstractDissolution and solubility of palladium in iron silicate melts saturated with alumina–iron spinel at 1300°C has been measured using an equilibration-drop quenching technique combined with electron probe microanalysis and laser ablation–inductive coupled plasma–mass spectrometry analysis from polished sections. Composition of the resulting Fe-Pd alloy allowed estimation of the activity of palladium at different oxygen partial pressures, and, thus, the solubilities of palladium in the studied slags in conditions typical of copper and nickel smelting as well as slag cleaning at pO2=10-5 to 10-10 atm. The mechanism of palladium dissolution in the studied iron silicate slags was oxidation by formation of the monovalent oxide species PdO0.5 over the entire oxygen activity range of this study. Testing the applicability of the various palladium isotopes for quantitative analyses of Pd in these types of matrices resulted in a good fit of measured concentrations of 104Pd and 105Pd with interference-corrected 106Pd and 108Pd.
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Piqueras, José Antonio, José Olivares, María Dolores Hidalgo, Pablo Vera-Villarroel, and Juan Carlos Marzo. "Psychometric Update of the Social Anxiety Screening Scale (SASS/EDAS) in a Spanish Adolescent Population." Spanish journal of psychology 14, no. 2 (November 2011): 977–89. http://dx.doi.org/10.5209/rev_sjop.2011.v14.n2.43.
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The aim of this work was to update the validation of the Social Anxiety Screening Scale (SASS/EDAS) in a sample of Spanish adolescents. To achieve this, one study with a sample of 1489 students in secondary education, of ages 14 to 17 years, were carried out. The psychometric properties of EDAS were examined through confirmatory factor analysis, reliability (Cronbach's alpha), temporal stability (test-retest), and concurrent criterion validity. The results supported the three-independent-factor structure (avoidance, distress and interference), that showed best fit indices compared to alternative models. They also showed that the scores of participants on EDAS scales were reliable in terms of internal consistency (α > .80) and moderately reliable concerning temporal stability (r= .48-.60) over a five-week period. The correlations between the EDAS factors and other social anxiety measures were positive and significant. Data provide empirical evidence of the estimation of reliability and validity of this scale. Future work should extend the validation of the EDAS in clinical samples.
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Liu, Yanli, Zhenchun Li, Guoquan Yang, and Qiang Liu. "An improved method to estimate Q based on the logarithmic spectrum of moving peak points." Interpretation 7, no. 2 (May 1, 2019): T255—T263. http://dx.doi.org/10.1190/int-2017-0234.1.
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The quality factor ([Formula: see text]) is an important parameter for measuring the attenuation of seismic waves. Reliable [Formula: see text] estimation and stable inverse [Formula: see text] filtering are expected to improve the resolution of seismic data and deep-layer energy. Many methods of estimating [Formula: see text] are based on an individual wavelet. However, it is difficult to extract the individual wavelet precisely from seismic reflection data. To avoid this problem, we have developed a method of directly estimating [Formula: see text] from reflection data. The core of the methodology is selecting the peak-frequency points to linear fit their logarithmic spectrum and time-frequency product. Then, we calculated [Formula: see text] according to the relationship between [Formula: see text] and the optimized slope. First, to get the peak frequency points at different times, we use the generalized S transform to produce the 2D high-precision time-frequency spectrum. According to the seismic wave attenuation mechanism, the logarithmic spectrum attenuates linearly with the product of frequency and time. Thus, the second step of the method is transforming a 2D spectrum into 1D by variable substitution. In the process of transformation, we only selected the peak frequency points to participate in the fitting process, which can reduce the impact of the interference on the spectrum. Third, we obtain the optimized slope by least-squares fitting. To demonstrate the reliability of our method, we applied it to a constant [Formula: see text] model and the real data of a work area. For the real data, we calculated the [Formula: see text] curve of the seismic trace near a well and we get the high-resolution section by using stable inverse [Formula: see text] filtering. The model and real data indicate that our method is effective and reliable for estimating the [Formula: see text] value.
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Su, Liyun, Meini Li, Shengli Zhao, and Ting Xie. "Distributed Sensor Local Linear Fusion Detection of Weak Pulse Signal in Chaotic Background." Journal of Sensors 2021 (February 10, 2021): 1–11. http://dx.doi.org/10.1155/2021/6661142.
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This paper combines the distributed sensor fusion system with the signal detection under chaotic noise to realize the distributed sensor fusion detection from chaotic background. First, based on the short-term predictability of the chaotic signal and its sensitivity to small interference, the phase space reconstruction of the observation signal of each sensor is carried out. Second, the distributed sensor local linear autoregressive (DS-LLAR) model is constructed to obtain the one-step prediction error of each sensor. Then, we construct a Bayesian risk model and also obtain the corresponding conditional probability density function under each sensor’s hypothesis test which firstly needs to fit the distribution of prediction errors according to the parameter estimation. Finally, the fusion optimization algorithm is designed based on the Bayesian fusion criterion, and the optimal decision rule of each sensor and the optimal fusion rule of the fusion center are jointly solved to effectively detect the weak pulse signal in the observation signal. Simulation experiments show that the proposed method which used a distributed sensor combined with a local linear model can effectively detect weak pulse signals from chaotic background.
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Ferreira, Jodavid A., Abraão D. C. Nascimento, and Alejandro C. Frery. "PolSAR Models with Multimodal Intensities." Remote Sensing 14, no. 20 (October 11, 2022): 5083. http://dx.doi.org/10.3390/rs14205083.
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Polarimetric synthetic aperture radar (PolSAR) systems are an important remote sensing tool. Such systems can provide high spacial resolution images, but they are contaminated by an interference pattern called multidimensional speckle. This fact requires that PolSAR images receive specialised treatment; particularly, tailored models which are close to PolSAR physical formation are sought. In this paper, we propose two new matrix models which arise from applying the stochastic summation approach to PolSAR, called compound truncated Poisson complex Wishart (CTPCW) and compound geometric complex Wishart (CGCW) distributions. These models offer the unique ability to express multimodal data. Some of their mathematical properties are derived and discussed—characteristic function and Mellin-kind log-cumulants (MLCs). Moreover, maximum likelihood (ML) estimation procedures via expectation maximisation algorithm for CTPCW and CGCW parameters are furnished as well as MLC-based goodness-of-fit graphical tools. Monte Carlo experiment results indicate ML estimates perform at what is asymptotically expected (small bias and mean square error) even for small sample sizes. Finally, our proposals are employed to describe actual PolSAR images, presenting evidence that they can outperform other well-known distributions, such as WmC, Gm0, and Km.
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Dewitt, Barry, David Feeny, Baruch Fischhoff, David Cella, Ron D. Hays, Rachel Hess, Paul A. Pilkonis, et al. "Estimation of a Preference-Based Summary Score for the Patient-Reported Outcomes Measurement Information System: The PROMIS®-Preference (PROPr) Scoring System." Medical Decision Making 38, no. 6 (June 26, 2018): 683–98. http://dx.doi.org/10.1177/0272989x18776637.
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Background. Health-related quality of life (HRQL) preference-based scores are used to assess the health of populations and patients and for cost-effectiveness analyses. The National Institutes of Health Patient-Reported Outcomes Measurement Information System (PROMIS®) consists of patient-reported outcome measures developed using item response theory. PROMIS is in need of a direct preference-based scoring system for assigning values to health states. Objective. To produce societal preference-based scores for 7 PROMIS domains: Cognitive Function–Abilities, Depression, Fatigue, Pain Interference, Physical Function, Sleep Disturbance, and Ability to Participate in Social Roles and Activities. Setting. Online survey of a US nationally representative sample ( n = 983). Methods. Preferences for PROMIS health states were elicited with the standard gamble to obtain both single-attribute scoring functions for each of the 7 PROMIS domains and a multiplicative multiattribute utility (scoring) function. Results. The 7 single-attribute scoring functions were fit using isotonic regression with linear interpolation. The multiplicative multiattribute summary function estimates utilities for PROMIS multiattribute health states on a scale where 0 is the utility of being dead and 1 the utility of “full health.” The lowest possible score is –0.022 (for a state viewed as worse than dead), and the highest possible score is 1. Limitations. The online survey systematically excludes some subgroups, such as the visually impaired and illiterate. Conclusions. A generic societal preference-based scoring system is now available for all studies using these 7 PROMIS health domains.
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Sa, Rula, Yonghui Nei, and Wenyi Fan. "Combining Multi-Dimensional SAR Parameters to Improve RVoG Model for Coniferous Forest Height Inversion Using ALOS-2 Data." Remote Sensing 15, no. 5 (February 25, 2023): 1272. http://dx.doi.org/10.3390/rs15051272.
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This paper considers extinction coefficient changes with height caused by the inhomogeneous distribution of scatterers in heterogeneous forests and uses the InSAR phase center height histogram and Gaussian function to fit the normalized extinction coefficient curve so as to reflect the vertical structure of the heterogeneous forest. Combining polarization decomposition based on the physical model and the PolInSAR parameter inversion method, the ground and volume coherence matrices can be separated based on the polarization characteristics and interference coherence diversity. By combining the new abovementioned parameters, the semi-empirical improved RVoG inversion model can be used to both quantify the effects of temporal decorrelation on coherence and phase errors and avoid the effects of small vertical wavenumbers on the large temporal baseline of spaceborne data. The model provided robust inversion for the height of the coniferous forest and enhanced the parameter estimation of the forest structure. This study addressed the influence of vertical structure differences on the extinction coefficient, though the coherence of the ground and volume in sparse vegetation areas could not be accurately estimated, and the oversensitivity of temporal decorrelation caused by inappropriate vertical wavenumbers. According to this method we used spaceborne L-band ALOS-2 PALSAR data on the Saihanba forest in Hebei Province acquired in 2020 for the purpose of height inversion, with a temporal baseline range of 14–70 days and the vertical wavenumber range of 0.01–0.03 rad/m. The results are further validated using sample data, with R2 reaching 0.67.
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Miles, Georgina M., Richard Siddans, Roy G. Grainger, Alfred J. Prata, Bradford Fisher, and Nickolay Krotkov. "Retrieval of volcanic SO<sub>2</sub> from HIRS/2 using optimal estimation." Atmospheric Measurement Techniques 10, no. 7 (July 26, 2017): 2687–702. http://dx.doi.org/10.5194/amt-10-2687-2017.
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Abstract. We present an optimal-estimation (OE) retrieval scheme for stratospheric sulfur dioxide from the High-Resolution Infrared Radiation Sounder 2 (HIRS/2) instruments on the NOAA and MetOp platforms, an infrared radiometer that has been operational since 1979. This algorithm is an improvement upon a previous method based on channel brightness temperature differences, which demonstrated the potential for monitoring volcanic SO2 using HIRS/2. The Prata method is fast but of limited accuracy. This algorithm uses an optimal-estimation retrieval approach yielding increased accuracy for only moderate computational cost. This is principally achieved by fitting the column water vapour and accounting for its interference in the retrieval of SO2. A cloud and aerosol model is used to evaluate the sensitivity of the scheme to the presence of ash and water/ice cloud. This identifies that cloud or ash above 6 km limits the accuracy of the water vapour fit, increasing the error in the SO2 estimate. Cloud top height is also retrieved. The scheme is applied to a case study event, the 1991 eruption of Cerro Hudson in Chile. The total erupted mass of SO2 is estimated to be 2300 kT ± 600 kT. This confirms it as one of the largest events since the 1991 eruption of Pinatubo, and of comparable scale to the Northern Hemisphere eruption of Kasatochi in 2008. This retrieval method yields a minimum mass per unit area detection limit of 3 DU, which is slightly less than that for the Total Ozone Mapping Spectrometer (TOMS), the only other instrument capable of monitoring SO2 from 1979 to 1996. We show an initial comparison to TOMS for part of this eruption, with broadly consistent results. Operating in the infrared (IR), HIRS has the advantage of being able to measure both during the day and at night, and there have frequently been multiple HIRS instruments operated simultaneously for better than daily sampling. If applied to all data from the series of past and future HIRS instruments, this method presents the opportunity to produce a comprehensive and consistent volcanic SO2 time series spanning over 40 years.
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Zeiger, Pierre, Frédéric Frappart, José Darrozes, Nicolas Roussel, Philippe Bonneton, Natalie Bonneton, and Guillaume Detandt. "SNR-Based Water Height Retrieval in Rivers: Application to High Amplitude Asymmetric Tides in the Garonne River." Remote Sensing 13, no. 9 (May 10, 2021): 1856. http://dx.doi.org/10.3390/rs13091856.
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Signal-to-noise ratio (SNR) time series acquired by a geodetic antenna were analyzed to retrieve water heights during asymmetric tides on a narrow river using the Interference Pattern Technique (IPT) from Global Navigation Satellite System Reflectometry (GNSS-R). The dynamic SNR method was selected because the elevation rate of the reflecting surface during rising tides is high in the Garonne River with macro tidal conditions. A new process was developed to filter out the noise introduced by the environmental conditions on the reflected signal due to the narrowness of the river compared to the size of the Fresnel areas, the presence of vegetation on the river banks, and the presence of boats causing multiple reflections. This process involved the removal of multipeaks in the Lomb-Scargle Periodogram (LSP) output and an iterative least square estimation (LSE) of the output heights. Evaluation of the results was performed against pressure-derived water heights. The best results were obtained using all GNSS bands (L1, L2, and L5) simultaneously: R = 0.99, ubRMSD = 0.31 m. We showed that the quality of the retrieved heights was consistent, whatever the vertical velocity of the reflecting surface, and was highly dependent on the number of satellites visible. The sampling period of our solution was 1 min with a 5-min moving window, and no tide models or fit were used in the inversion process. This highlights the potential of the dynamic SNR method to detect and monitor extreme events with GNSS-R, including those affecting inland waters such as flash floods.
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Kastridis, Aristeidis, and Dimitrios Stathis. "Evaluation of Hydrological and Hydraulic Models Applied in Typical Mediterranean Ungauged Watersheds Using Post-Flash-Flood Measurements." Hydrology 7, no. 1 (February 18, 2020): 12. http://dx.doi.org/10.3390/hydrology7010012.
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In this paper, three different flash floods episodes were analyzed, which occurred in October 2006, February 2010, and June 2018 in the Chalkidiki peninsula (North Greece). The Soil Conservation Service (SCS) model and a revised assessment of the CN parameter were applied to estimate the flood hydrographs, and Hydrologic Engineering Center’s-River Analysis System (HEC-RAS) software was used for the flood simulations. Initially, hydrological and hydraulic models were calibrated at Vatonias watershed (240.90 km2, North Greece), where three rain gauges and one water level station are located. Vatonias is located very close to the Stavros ungauged watersheds and presents similar geomorphology and land use conditions. The effectiveness and accuracy of the methodology were validated using post-flash-flood measurements. The root mean square error goodness of fit was used to compare the observed and simulated flood depths. Critical success index was calculated for the assessment of the accuracy of observed and modeled flooded areas. The results showed that the dense forest vegetation was not capable of preventing the flash flood generation or reducing the peak discharge, especially in small watersheds characterized by short concentration times. The main cause of flash flood generation was the human interference that influenced the hydraulic characteristics of streams and floodplains. The revised assessment of the CN parameter enhanced the estimation and spatial distribution of CN over the entire watershed. The results revealed that the proposed methodology could be a very useful tool to researchers and policy makers for flood risk assessment of higher accuracy and effectiveness in ungauged Mediterranean watersheds.
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Costa, Yuri A., Carlos P. Filho, Gabriela A. Flores, Evandro L. L. Rodrigues, and Fernando F. Paiva. "Full-Range Liver Fat Fraction Estimation in Magnitude MRI Using a Signal Shape Descriptor." Concepts in Magnetic Resonance Part A 2019 (July 9, 2019): 1–11. http://dx.doi.org/10.1155/2019/3439468.
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Current methods for estimation of proton density fat fraction (PDFF) of the liver using magnitude magnetic resonance (MR) imaging face the challenge of correctly estimating it when fat is the dominant molecule; i.e., PDFF is more than 50%. Therefore, the accuracy of the methods is limited to half-range operation. We introduce a method based on neural networks for regression capable of estimating over the full range of fat fractions. We built a neural network based on the angles and distances between the data in the discrete MR signal (ADALIFE), using these as features associated with different PDFFs and as input for the network. Tests were performed using ADALIFE and Multi-interference, a state-of-the-art method to estimate PDFFs, with simulated signals at various signal-to-noise (SNR) values. Results were compared in order to verify repeatability and agreement using Bland-Altman and REC curves. Results for Multi-interference were similar to its in vivo literature, showing the relevance of a simulation. ADALIFE was able to correctly estimate fat fractions up to 100%, breaking the current paradigm for full-range estimation using only offline postprocessing. Within half range, our method outperformed Multi-interference in repeatability and agreement, with narrower limits of agreement and lower expected error at any SNR.
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Corradini, S., L. Merucci, and A. J. Prata. "Retrieval of SO<sub>2</sub> from thermal infrared satellite measurements: correction procedures for the effects of volcanic ash." Atmospheric Measurement Techniques Discussions 2, no. 1 (February 9, 2009): 303–42. http://dx.doi.org/10.5194/amtd-2-303-2009.
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Abstract. The simultaneous presence of SO2 and ash in a volcanic plume can lead to a significant error in the SO2 columnar abundance retrieval when multispectral Thermal InfraRed (TIR) data are used. The ash particles within the plume with effective radii (from 1 to 10 μm) reduce the Top Of Atmosphere (TOA) radiance in the entire TIR spectral range, including the channels used for SO2 retrieval. The net effect is a significant SO2 overestimation. In this work the interference of ash is discussed and two correction procedures for satellite SO2 volcanic plume retrieval in the TIR spectral range are developed to achieve an higher computation speed and a better accuracy. The ash correction can be applied when the sensor spectral range includes the 7.3 and/or 8.7 μm SO2 absorption bands, and the split window bands centered around 11 and 12 μm required for ash retrieval. This allows the possibility of a simultaneous estimation of both volcanic SO2 and ash in the same data set. The proposed ash correction procedures have been applied to the Moderate Resolution Imaging Spectroradiometer (MODIS) and the Spin Enhanced Visible and Infrared Imager (SEVIRI) measurements. Data collected during the 24 November 2006 Mt. Etna eruption have been used to illustrate the technique. The SO2 and ash estimations are carried out by using a least squares fit method and the Brightness Temperature Difference (BTD) procedures, respectively. The simulated TOA radiance Look-Up Table (LUT) needed for the SO2 columnar abundance and the ash retrievals have been computed using the MODTRAN 4 Radiative Transfer Model. The results show the importance of the ash correction on SO2 retrieval at 8.7 μm – the SO2 columnar abundance corrected by the ash influence is less than one half of the values retrieved without the correction. The ash correction on SO2 retrieval at 7.3 μm is much less important and only significant for low SO2 columnar abundances. Results also show that the simplified and faster correction procedure underestimates the ash correction compared with the more time consuming but more accurate correction procedure. Such underestimation is greater for instruments having better ground pixel resolution, i.e. greater for MODIS than for SEVIRI.
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Corradini, S., L. Merucci, and A. J. Prata. "Retrieval of SO<sub>2</sub> from thermal infrared satellite measurements: correction procedures for the effects of volcanic ash." Atmospheric Measurement Techniques 2, no. 1 (May 26, 2009): 177–91. http://dx.doi.org/10.5194/amt-2-177-2009.
Full textAbstract:
Abstract. The simultaneous presence of SO2 and ash in a volcanic plume can lead to a significant error in the SO2 column abundance retrieval when multispectral Thermal InfraRed (TIR) data are used. The ash particles within the plume with effective radii from 1 to 10 μm reduce the Top Of Atmosphere (TOA) radiance in the entire TIR spectral range, including the channels used for SO2 retrieval. The net effect is a significant SO2 overestimation. In this work the interference of ash is discussed and two correction procedures for satellite SO2 volcanic plume retrieval in the TIR spectral range are developed to achieve an higher computational speed and a better accuracy. The ash correction can be applied when the sensor spectral range includes the 7.3 and/or 8.7 μm SO2 absorption bands, and the split window bands centered around 11 and 12 μm required for ash retrieval. This allows the possibility of simultaneous estimation of both volcanic SO2 and ash in the same data set. The proposed ash correction procedures have been applied to the Moderate Resolution Imaging Spectroradiometer (MODIS) and the Spin Enhanced Visible and Infrared Imager (SEVIRI) measurements. Data collected during the 24 November 2006 Mt. Etna eruption have been used to illustrate the technique. The SO2 and ash estimation is carried out by using a best weighted least squares fit method and the Brightness Temperature Difference (BTD) procedures, respectively. The simulated TOA radiance Look-Up Table (LUT) needed for the SO2 column abundance and the ash retrievals have been computed using the MODTRAN 4 Radiative Transfer Model. The results show the importance of the ash correction on SO2 retrievals at 8.7 μm, where the corrected SO2 column abundance values are less than 50% of the uncorrected values. The ash correction on SO2 retrieval at 7.3 μm is much less important and only significant for low SO2 column abundances. Results also show that the simplified and faster correction procedure underestimates the ash correction compared with the more time consuming but more accurate correction procedure. Such underestimation is greater for instruments having better ground pixel resolution, i.e. greater for MODIS than for SEVIRI.
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Kato, K., T. Kayaba, I. Nitta, and S. Shimoda. "The Effect of Surface Roughness on Fitting Strength of Shrink Fit Between Ceramic and Metal Elements." Journal of Vibration and Acoustics 111, no. 3 (July 1, 1989): 318–25. http://dx.doi.org/10.1115/1.3269859.
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Shrink fit is a basic and simple technique for joining metal elements. But it is not suitable for ceramic and metal elements, especially at elevated temperatures. For the accurate estimation of fitting strength between ceramic and metal elements, an understanding of the deformation of surface micro-asperities during contact is introduced in this paper. The elastic deformation of a shaft and a cylinder and the elastic-plastic deformation of the asperities were taken into consideration for the theoretical fitting strength. Theoretical estimations of fitting strength between a ceramic shaft and a metal cylinder showed good agreement wtih experimental values in various fitting interferences and at temperatures of 20°C–180°C.
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Deng, Leilei, and Kaijing Leng. "Application of two spectrum refinement methods in frequency estimation." Journal of Physics: Conference Series 2290, no. 1 (June 1, 2022): 012070. http://dx.doi.org/10.1088/1742-6596/2290/1/012070.
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Abstract Considering the limitation of FFT frequency estimation method in resolution, this paper briefly introduces the complex modulation ZOOM-FFT and Chirp-Z transform spectrum zooming methods. The simulation results show that the ZOOM-FFT method has better anti spectrum leakage and interference effect. Furthermore, the two methods are applied to the frequency estimation of underwater high-speed maneuvering target, and it is found that Chirp-Z transform method can obtain smoother and stable frequency history, and has more flexible frequency resolution.
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He, Qi-fang, Qun Zhang, Ying Luo, and Li Sun. "Sinusoidal Frequency Modulation Fourier-Bessel Series for Multicomponent SFM Signal Estimation and Separation." Mathematical Problems in Engineering 2017 (2017): 1–14. http://dx.doi.org/10.1155/2017/5852171.
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Multicomponent sinusoidal frequency modulated (SFM) signals are widely used in radar, acoustics, and biomedicine. The instantaneous frequency (IF) characterizes important physical parameters of the real applications. In this paper, a sinusoidal frequency modulation Fourier-Bessel (SFMFB) series is defined for IF estimation. It provides the signal decomposition on the Bessel function basis with a finer resolution, which proposes an extension of the performance and the applicability of the classic Fourier-Bessel transform (FBT). Based on the property analysis of the SFMFB series, an algorithm of IF estimation and signal separation is introduced. Unlike the existing estimation methods which apply sliding windows to make an instantaneous approximation, the proposed method uses the global data, which provides a longer period gain, therefore achieving a better estimation performance. Moreover, considering that most estimation methods are invalid in multicomponent separation, the individual signals are well separated by the proposed algorithm, which facilitates the further monocomponent analysis. A performance comparison between the proposed method, the FBT, and another recently proposed sinusoidal frequency modulation Fourier transform (SFMFT) is also provided. Simulation results indicate that the proposed method outperforms the existing methods in estimation precision and computation load, and it is free of interference which exists in SFMFT.
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Weaver, Susan E., Nancy Smits, and Chin S. Tan. "Estimating Yield Losses of Tomatoes (Lycopersicon esculentum) Caused by Nightshade (Solanumspp.) Interference." Weed Science 35, no. 2 (March 1987): 163–68. http://dx.doi.org/10.1017/s004317450007898x.
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Reductions in yields of processing tomatoes (Lycopersicon esculentumMill. ‘H2653’ and ‘Earlirouge′) caused by interference from eastern black nightshade (Solanum ptycanthumDun. # SOLPT) and hairy nighthsade (S. sarrachoidesSendt. # SOLSA) were estimated for transplanted and seeded tomatoes at two locations in southern Ontario. Tomato yield losses were significantly greater in seeded than in transplanted tomatoes. Stomatal conductance and transpiration rates of seeded tomatoes decreased more rapidly with increased nightshade density than did those of transplanted tomatoes. Percent yield losses also differed between sites. Seeded tomatoes grown at high density in twin rows (33 300 and 45 000 plants/ha) had higher yields and lower percent yield losses than did tomatoes grown at low density in single rows (12 500 to 22 500 plants/ha). Nightshade dry weight and seed production decreased per plant but increased per unit area with increasing nightshade density. Nightshade dry weights and seed production did not vary with site or method of tomato establishment. A hyperbolic model provided an excellent fit to data on both tomato yield losses and nightshade seed production as a function of nightshade density.
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Zhang, Zhou, and Wang. "A Novel Noise Suppression Channel Estimation Method Based on Adaptive Weighted Averaging for OFDM Systems." Symmetry 11, no. 8 (August 3, 2019): 997. http://dx.doi.org/10.3390/sym11080997.
Full textAbstract:
Orthogonal frequency division multiplexing (OFDM) systems have inherent symmetric properties, such as coding and decoding, constellation mapping and demapping, inverse fast Fourier transform (IFFT) and fast Fourier transform (FFT) operations corresponding to multi-carrier modulation and demodulation, and channel estimation is a necessary module to resist channel fading in the OFDM system. However, the noise in the channel will significantly affect the accuracy of channel estimation, which further affects the recovery quality of the final received signals. Therefore, this paper proposes an efficient noise suppression channel estimation method for OFDM systems based on adaptive weighted averaging. The basic idea of the proposed method is averaging the last few channel coefficients obtained from coarse estimation to suppress the noise effect, while the average frame number is adaptively adjusted by combining Doppler spread and signal-to-noise ratio (SNR) information. Meanwhile, to better combat the negative effect brought by Doppler spread and inter-carrier interference (ICI), the proposed method introduces a weighting factor to correct the weighted value of each frame in the averaging process. Simulation results show that the proposed channel estimation method is effective and provides better performance compared with other conventional channel estimation methods.
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Dieleman, Anita, Allan S. Hamill, Stephan F. Weise, and Clarence J. Swanton. "Empirical Models of Pigweed (Amaranthusspp.) Interference in Soybean (Glycine max)." Weed Science 43, no. 4 (December 1995): 612–18. http://dx.doi.org/10.1017/s0043174500081728.
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Three empirical crop yield loss models were used to describe the interference of redroot pigweed and Powell amaranth populations with soybean. Data were obtained from field experiments conducted in 1992 and 1993. Pigweed densities of 0 to eight plants m−1were established within the soybean row. Pigweed sowing dates were selected so that weed seedling emergence coincided with VE, VC, and V2 soybean growth stages within the time frame of the critical weed-free period. The model incorporating pigweed density and time of emergence gave the best description of soybean yield loss in comparison to the two relative leaf area models. This model was fit to a combined data set of percent yield loss because parameter estimates did not differ among locations and years. Estimated soybean yield losses decreased from 16.4 to 0.5% with delayed pigweed emergence from 0 to 20 degree days. Leaf area of pigweed relative to soybean encompassed pigweed density and time of emergence. Relationship between relative leaf area and soybean yield loss was best described by the one-parameter model estimating a relative damage coefficient ‘q’ than the two-parameter model that also estimated maximum expected yield loss. The relative damage coefficient ‘q’ decreased with later times of leaf area assessment but could be predicted with one leaf area observation. Empirical models that incorporate time of weed emergence represent a step toward improving predictions of yield loss. This is important for the selection of cost-effective weed control strategies.
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Al-Asady, Heba Abdul-Jaleel, Hassan Falah Fakhruldeen, and Mustafa Qahtan Alsudani. "Channel estimation of OFDM in C-band communication systems under different distribution conditions." Indonesian Journal of Electrical Engineering and Computer Science 23, no. 3 (September 1, 2021): 1778. http://dx.doi.org/10.11591/ijeecs.v23.i3.pp1778-1782.
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<p>Orthogonal frequency division multiplexing (OFDM) is a transmission system that uses multiple orthogonal carriers that are sent out at the same time. OFDM is a technique for mobile and wireless communication that has high-efficient frequency utilization, high data-rate transmission, simple and efficient implementation using the fast Fourier transform (FFT) and the inverse fast Fourier transform (IFFT), and reduces inter symbol interference (ISI) by inserting cyclic prefix (CP). One of the most important approaches in an OFDM system is channel estimation. In this paper, the orthogonal frequency division multiplexing system with the Rayleigh channel module is analyzed for different areas. The proposed approach used large numbers of subcarriers to transmit the signals over 64-QAM modulation with pilot add channel estimation. The accuracy of the OFDM system is shown in the measuring of the relationships of peak power to the noise ratio and bit error rate.</p>
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Gong, Xiaorong, Shudong Chen, and Shuang Zhang. "JOM-4S Overhauser Magnetometer and Sensitivity Estimation." Sensors 21, no. 22 (November 19, 2021): 7698. http://dx.doi.org/10.3390/s21227698.
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The Overhauser magnetometer is a scalar quantum magnetometer based on the dynamic nuclear polarization (DNP) effect in the Earth’s magnetic field. Sensitivity is a key technical specification reflecting the ability of instruments to sense small variations of the Earth’s magnetic field and is closely related to the signal-to-noise ratio (SNR) of the free induction decay (FID) signal. In this study, deuterated 15N TEMPONE radical is used in our sensor to obtain high DNP enhancement. The measured SNR of the FID signal is approximately 63/1, and the transverse relaxation time T2 is 2.68 s. The direct measurement method with a single instrument and the synchronous measurement method with two instruments are discussed for sensitivity estimation in time and frequency domains under different electromagnetic interference (EMI) environments and different time periods. For the first time, the correlation coefficient of the magnetic field measured by the two instruments is used to judge the degree of the influence of the environmental noise on the sensitivity estimation. The sensitivity evaluation in the field environment is successfully realized without electrical and magnetic shields. The direct measurement method is susceptible to EMI and cannot work in general electromagnetic environments, except it is sufficiently quiet. The synchronous measurement method has an excellent ability to remove most natural and artificial EMIs and can be used under noisy environments. Direct and synchronous experimental results show that the estimated sensitivity of the JOM-4S magnetometer is approximately 0.01 nT in time domain and approximately 0.01 nT/Hz in frequency domain at a 3 s cycling time. This study provides a low-cost, simple, and effective sensitivity estimation method, which is especially suitable for developers and users to estimate the performance of the instrument.
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Altube, Patricia, Joan Bech, Oriol Argemí, and Tomeu Rigo. "Quality Control of Antenna Alignment and Receiver Calibration Using the Sun: Adaptation to Midrange Weather Radar Observations at Low Elevation Angles." Journal of Atmospheric and Oceanic Technology 32, no. 5 (May 2015): 927–42. http://dx.doi.org/10.1175/jtech-d-14-00116.1.
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AbstractA quality control method for combined online monitoring of weather radar antenna pointing biases and receiver calibration using solar signals detected by an operational radar is adapted for application to midrange radar data (80–150 km). As the original method was developed using long-range data, additional criteria based on robust statistical estimators are imposed in the sun signature detection and selection process, allowing to discard observations biased by ground clutter or precipitation and to remove very influential outliers. The validity ranges of the physical model describing the solar interferences detected by the scanning radar antenna are explicitly defined and an equation for estimation of the effective scanning width in reception is provided in a thorough theoretical derivation. The method proposed reveals its sensitivity to changes in the antenna pointing accuracy and receiver calibration when applied to operational data obtained with three C-band radars during one year. A comparative study on the goodness of fit between a three- and a five-parameter model highlights the effect on the stability and accuracy of the antenna and receiver parameters retrieved for each radar system, considering the dissimilar information content of the observations collected by each radar. The performance of the proposed methodology under the effects of the presence of ground clutter and radio local area network interferences is discussed in the results presented.
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Chen, Weiyi, Jenny L. Wilson, Mohammad Khaksari, Michael A. Cowley, and Pablo J. Enriori. "Abdominal fat analyzed by DEXA scan reflects visceral body fat and improves the phenotype description and the assessment of metabolic risk in mice." American Journal of Physiology-Endocrinology and Metabolism 303, no. 5 (September 1, 2012): E635—E643. http://dx.doi.org/10.1152/ajpendo.00078.2012.
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Clinical studies have demonstrated a strong relationship between visceral fat content and metabolic diseases, such as type 2 diabetes and liver steatosis. Obese mouse models are an excellent tool to study metabolic diseases; however, there are limited methods for the noninvasive measurement of fat distribution in mice. Although micromagnetic resonance imaging and microcomputed tomography are the “gold standards” in the measurement of fat distribution, more economical and accessible methods are required. Dual energy X-ray absorptiometry (DEXA) is an effective method in characterizing fat content; however, it cannot discriminate between visceral and subcutaneous fat depots. We demonstrate that an evaluation of abdominal fat content measured by DEXA through the selection of one localized abdominal area strongly correlates with visceral fat content in C57BL/6J mice. We found that DEXA is able to measure fat pad volume ex vivo with high accuracy; however, the measurement of visceral fat in vivo shows an overestimation caused by subcutaneous tissue interference. The overestimation is almost constant for a wide range of values, and thus it is possible to correct the data for a more accurate estimation of visceral fat content. We demonstrate the utility of this technique in characterizing phenotypes of several obese mouse models ( ob/ob, db/db, MC4R-KO, and DIO) and evaluating the effect of treatments on visceral fat content in longitudinal studies. Additionally, we also establish abdominal obesity as a potential biomarker for metabolic abnormalities (liver fat accumulation, insulin resistance/diabetes) in mice, similar to that described in humans.
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Nita, Gelu M., Aard Keimpema, and Zsolt Paragi. "Statistical Discrimination of RFI and Astronomical Transients in 2-bit Digitized Time Domain Signals." Journal of Astronomical Instrumentation 08, no. 01 (March 2019): 1940008. http://dx.doi.org/10.1142/s2251171719400087.
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We investigate the performance of the generalized Spectral Kurtosis (SK) estimator in detecting and discriminating natural and artificial, very short duration transients in the 2-bit sampling time domain Very-Long-Baseline Interferometry (VLBI) data. We demonstrate that, while both types of transients may be efficiently detected, their natural or artificial nature cannot be distinguished if only a time domain SK analysis is performed. However, these two types of transients become distinguishable from each other in the spectral domain, after a 32-bit FFT operation is performed on the 2-bit time domain voltages. We discuss the implication of these findings on the ability of the Spectral Kurtosis estimator to automatically detect bright astronomical transient signals of interests, such as pulsar or fast radio bursts (FRB), in VLBI data streams that have been severely contaminated by unwanted radio frequency interference.
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Zhan, Lang, Phil S. Fair, Robert J. Dombrowski, Edwin N. Quint, and Richard Cao. "Estimating Ultralow Permeability at Multiple Locations Using Simultaneous-Impulse Tests: A Fit-for-Purpose Pressure-Transient Solution and Its Field Application." SPE Journal 23, no. 04 (June 11, 2018): 1184–200. http://dx.doi.org/10.2118/187063-pa.
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Summary One of the major challenges in efficiently developing ultratight or shale reservoirs is to obtain reliable permeability distribution. Ultralow permeability and very strong stratification or heterogeneity in the formations require conducting long-duration tests at multiple locations in a well to attain a complete reservoir characterization. Because of these characteristics, existing tools or methods that work well for conventional reservoirs are usually not applicable for ultralow-permeability formations. An innovative reservoir-monitoring/testing tool system was developed and successfully applied to fields in both the United States and Canada (Zhan et al. 2016). The tool created multiple pressure pulses at targeted locations simultaneously along monitoring wells for zonal in-situ permeability estimations as well as long-term formation-pressure monitoring. Existing pressure-transient solutions are incapable of handling the measured data when potential zonal-pressure interferences appear. A fit-for-purpose pressure solution, the associated optimization algorithm, and a suitable data-interpretation work flow were developed to analyze the data whenever commercial software tools are inadequate. The new solution fully considers all impulses as well as potential interferences among them through suitable superposition. In-situ permeability values at all involved zones can be obtained through a combination of individual-impulse analyses and systematic multiple-impulse inversions. The new pressure-transient solution was verified through comprehensive synthetic cases using numerical simulations. The results show that the solution can handle either fully or partially open wellbores in each zone and properly considers crossflow between formation layers. In addition, it allows any number of perforated intervals and formation layers where the number of perforated intervals is fewer than that of the formation layers. Field examples demonstrate the applicability of the new solution and the data-interpretation work flow to formation permeability down to tens of nanodarcies. The detailed zonal-permeability distribution in the formation enables a more-representative reservoir model for better hydraulic-fracturing design and field-development optimization.
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Mendoza, Tito R., Amylou C. Dueck, Qiuling Shi, Haijun Ma, Jeffrey Zhang, Yi Qian, and Charles S. Cleeland. "The Significant Contribution of Pain in Determining the Health Status of Patients with Multiple Myeloma (MM)." Blood 126, no. 23 (December 3, 2015): 4495. http://dx.doi.org/10.1182/blood.v126.23.4495.4495.
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Abstract BACKGROUND: Most cancer patients with bone metastases report significant pain and substantial impairment in their ability to function. In particular, patients with MM are susceptible to bone pain because of bone damage. Patient-reported outcomes such as a general health outcome measure and a legacy pain instrument may provide valuable information in determining the impact of this condition. The goal of this study was to provide a descriptive profile of health status for cancer patients using the EQ-5D-3L (EQ-5D), a commonly used tool to measure health utility scores. Another goal is to evaluate the predictive information provided by the Brief Pain Inventory (BPI), a self-report pain assessment tool designed to capture pain severity and interference in patients. These information may be useful in estimating the health status of patients where the EQ-5D was not administered. METHODS: Data was pooled across three denosumab registrational trials '20050136', '20050103', and '20050244'. Patients completed the EQ-5D and the BPI at baseline. Eligible patients had histologically confirmed advanced cancers, radiographic evidence of at least one bone metastasis (or lytic bone lesion from multiple myeloma), ECOG of 2 or better and adequate organ function. Using data from patients with MM (N=168), descriptive statistics were used to present summary information on health-related quality of life states and utility scores. Linear regressions were used to examine how BPI severity and interference subscale scores relate with EQ-5D utility scores. Ordinal regressions were used to evaluate how well BPI items predict EQ-5D individual items. Bonferroni adjustments were made when evaluating the relationships of BPI items to individual EQ-5D items. These analyses were repeated using data across several groups of cancer patients to determine if similar results can be obtained (breast cancer, N=2,044, prostate cancer, N=1,819 and others, N=1,509). RESULTS: About 9% of MM patients reported perfect health compared with 11% of all cancer patients. Of the 5 dimensions measured by the EQ-5D, the MM cohort rated pain (80%) the highest with moderate to extreme problems. This was followed by usual activities (68%), mobility (63%), anxiety/depression (49%), and self-care (36%). Similar order was observed across all cancer groups, but with slightly lower percentages for most items: pain (78%), usual activities (58%), mobility (55%), anxiety/depression (57%), and self-care (26%). Although pain interference subscale score explained more of the variability in the EQ-5D utility scores compared with pain severity items in the MM cohort (39% vs 31%) and for all patients (41% vs 34%), model fit was less than ideal (mean squared error=0.23 - 0.25). Hence, BPI items were fitted into individual EQ-5D items. Ordinal regression models fitting BPI items into individual EQ-5D items for the MM cohort showed good predictive power as measured by the concordance index c for mobility (86%), self-care (80%), usual activities (83%), pain (90%) and anxiety/depression (78%). For all patients, similar model fit were obtained for mobility (83%), self-care (78%), usual activities (81%), pain (90%) and anxiety/depression (72%). Further examination of the ordinal regression models across all groups showed that three BPI pain severity items, 'pain at its worst', 'average pain' and 'pain now' in addition to interference with activity and interference with work significantly predicted the EQ-5D pain item. Five interference items, activity, walking ability, work, sleep and enjoyment of life significantly predicted the EQ-5D usual activities item. Finally, 'pain now' and four interference items, relationship with others, enjoyment of life, mood, and activity significantly predicted the EQ-5D anxiety/depression item. CONCLUSIONS: Patients with MM reported several functional limitations on the EQ-5D. Majority of the patients reported moderate to extreme problems in all EQ-5D dimensions except self-care. Model fit of ordinal regression models relating BPI items with EQ-5D items are reasonable underscoring the benefit of using the BPI for planning patient care and health status evaluation. This consistency was also found across cancer groups that primarily include breast and prostate. The resultant model demonstrates the significant contribution of pain severity and interference in determining health status in this patient population. Disclosures Mendoza: Amgen Inc.: Consultancy. Shi:Amgen Inc.: Consultancy. Ma:Amgen Inc.: Employment. Zhang:Amgen Inc.: Employment. Qian:Amgen Inc.: Employment. Cleeland:Amgen Inc.: Consultancy.
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Zhang, Lin Xi, Peng Song, and Ying Jun Zhang. "A Novel Method Based on Cyclic Spectral Analysis about Carrier Frequency Estimation in the UAV Data Chain." Advanced Engineering Forum 6-7 (September 2012): 215–20. http://dx.doi.org/10.4028/www.scientific.net/aef.6-7.215.
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When UAV works on the end of the task path, or affected by waves transmission environment and the influence of the electromagnetic interference, the signal of receiver will be made low signal-to-noise ratio (SNR) signal and the phase lock loop (PLL) using for carrier extraction will performance serious decline or loss locks. Therefore, in order to ensure UAV completed a predefined task successfully, low SNR carrier recovery has become one of the key technologies in the UAV data chain. In this paper, based on the basic concept of cyclic spectral analysis, we research and give the cyclic autocorrelation function and the cyclic spectral density function of the BPSK modulation signal. We emphasis a computer simulation method based on the time-smoothing FFT accumulation method and use this method to verify cyclic spectral analysis is still effective to estimate the carrier frequency when the SNR is -10 dB.
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Enamorado-Báez, S. M., J. M. Abril, and J. M. Gómez-Guzmán. "Determination of 25 Trace Element Concentrations in Biological Reference Materials by ICP-MS following Different Microwave-Assisted Acid Digestion Methods Based on Scaling Masses of Digested Samples." ISRN Analytical Chemistry 2013 (June 27, 2013): 1–14. http://dx.doi.org/10.1155/2013/851713.
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The use of normalized procedures designed for soil and sediment samples (like US-EPA 3051) to chemically prepare some kind of organic samples is a common practice in some laboratories. However, the performance of this method for other matrices has to be demonstrated. Three microwave-assisted digestion procedures with 0.5 g of sample and simplified reagents (10 mL HNO3 alone and mixtures of HNO3/HCl- and HNO3/H2O2 procedures A, B, and C, resp.) were compared for quantitative determination of 25 elements (Be, B, Al, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Sr, Mo, Ag, Cd, Sb, Cs, Ba, Tl, Pb, Th and U) in three biological reference materials provided by NIST (mussel tissue (MT), tomato leaves (TL), and milk powder (MP)) by ICP-MS. From scaling masses (from 0.1 up to 0.9 g at 0.1 g interval) in procedure A, a linear relationship among instrumental signal and mass of digested sample could be constructed at 99% CL for most of the target analytes. The slope of this linear fit provided the estimation of sample concentration, while the ordinate in origin allowed the identification of matrix interferences which were absent in the reagent blank.
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Li, Jialing, I.-Tai Lu, and Enoch Lu. "Robust MMSE Transceiver Designs for Downlink MIMO Systems with Multicell Cooperation." International Journal of Digital Multimedia Broadcasting 2010 (2010): 1–19. http://dx.doi.org/10.1155/2010/815704.
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Therobust-generalized iterative approach(Robust-GIA),robust-fast iterative approach(Robust-FIA), androbust-decoder covariance optimization approach(Robust-DCOA) are proposed for designing MMSE transceivers of downlink multicell multiuser MIMO systems with per-cell and per-antenna power constraints and possibly imperfect channel state information. TheRobust-DCOAis the most restrictive but is always optimum, theRobust-GIAis the most general, and theRobust-FIAis the most efficient. When theRobust-DCOAis applicable and the decoder covariance matrices are full rank, the three proposed approaches are equivalent and all provide the optimum solution. Numerical results show that the proposed robust approaches outperform their non-robust counterparts in various single-cell and multicell examples with different system configurations, channel correlations, power constraints, and cooperation scenarios. Moreover, performances of the robust approaches are insensitive to estimation errors of channel statistics (correlations and path loss). With cell-cooperation, cell edge interference problems can be remedied without reducing the number of data streams by using the proposed robust approaches.
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Puricer, Kovar, and Barta. "Modernized Solar Radio Spectrograph in the L Band Based on Software Defined Radio." Electronics 8, no. 8 (August 3, 2019): 861. http://dx.doi.org/10.3390/electronics8080861.
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The paper presents the concept, implementation, and test operation of a modernized solar radio spectrograph for an investigation of the solar emission and solar bursts in radio frequency bands. Besides having a strong diagnostic significance for studying the flare energy release, the solar radio bursts can also cause strong interference for radio communication and navigation systems. The current spectrograph for the Ondrejov observatory (Astronomical Institute of Czech Academy of Sciences) was modernized by using a direct-conversion receiver connected to a field-programmable gate array (FPGA) for the fast Fourier transform (FFT) spectrum estimation and put into the test operation. The higher time and frequency resolution and lower noise in comparison with the existing analog instrument were reached by the implementation of the latest optimal signal processing methods. To reduce the costs for such modernization, the operating frequency range was divided into four sub-bands of bandwidth 250 MHz, which brings another benefit of greater scalability. The first observations obtained by the new spectrograph and their comparison with the analog device are presented in the paper with future steps to put the spectrograph into the regular operation.
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Hussain, Arif, Arslan Ahmed, Hina Magsi, Jahangeer Badar Soomro, Syed Sabir Hussain Bukhari, and Jong-Suk Ro. "Adaptive Data Length Method for GPS Signal Acquisition in Weak to Strong Fading Conditions." Electronics 10, no. 14 (July 19, 2021): 1735. http://dx.doi.org/10.3390/electronics10141735.
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Satellite-based navigation is an essential part of all the technology-dependent applications, such as road transport, cell phones, the medical field, aviation or the shipping industry, etc. The performance of the navigation systems depends upon how quickly they can acquire and process the received signals for positioning solutions. However, in dense urban or indoor environments, signal acquisition can be a challenging task due to fading as a result of multipath and/or interference. This paper presents post-processing acquisition results on Global Positioning System (GPS) signals to study the relationship between data lengths used for signal acquisition and the achieved signal power using a Fast Fourier Transform (FFT)-based circular correlation method. Based on this study, the detection performance of the FFT-based method has also been analyzed by intentionally degrading the signal power levels. A new Adaptive Data length (ADL) method for acquisition has been proposed in this paper, which can be used for speeding up the acquisition process and uses adaptive data lengths rather than fixed data lengths. The ADL method works by estimating the threshold level based on the noise present in the signal and then comparing it with the signal power levels. Less difference between the threshold level and signal power level means less data length will be used while more difference means that more data length will be used for acquisition. The proposed algorithm can be used in commercially available receivers for adopting to an adaptive acquisition process for increased efficiency.
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Al-A'miri, Zeineb Sabeeh Hameed, and Khadeeja Sadiq Jaffer Al-Hussainy. "Studying Chemical Composition of Myofibril and Sarcoplasmic Proteins Separated From Different Types of Meats." IOP Conference Series: Earth and Environmental Science 910, no. 1 (November 1, 2021): 012109. http://dx.doi.org/10.1088/1755-1315/910/1/012109.
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Abstract The present study was dealt with the estimation of the chemical composition (moisture, protein, fat, and ash) and physical properties (pH and water holding capacity) of camel, duck, and tuna meat purchased from local markets. Muscle proteins were separated, including myofibril and sarcoplasmic proteins from these meats, estimation of the yield and study of their content. have been studied. the results were as follows: 1. Statistical results disclosed that there was a significant difference at a probability level (P≤0.05) in the percentage of moisture, protein, fat, ash, pH, and values of water holding capability in each of camel, duck, and tuna's meat. 2. Statistical results made a clear reference that there were significant differences at a probability level (P≤0.05) in the percentage of yield, moisture, protein, fat, and ash of myofibril and sarcoplasmic proteins in each of camel, duck, and tuna's meat. Also, a dual interference between meat type and protein type was significant in its impact on percentages of yield and chemical composition. 3. It was observed the percentage of moisture and fat in tuna meat was higher than the percentage of moisture in duck meat. As to the lowest percentage of moisture, it was in the meat of tuna, while the tuna meat recorded the highest percentage in protein and ash, then followed by the percentage of protein and ash in duck meat, while camel's meat recorded the lowest percentage of protein and ash. Besides, results indicated that the values of pH and water holding capability of duck meat were higher than that in the meat of tuna meat and camel. 4. It was found that the percentage of the yield for proteins of a myofibril of duck meat was higher than that in the meat of tuna and camels, as the percentage of yield of sarcoplasmic proteins for tuna was higher than that in the meat of duck and camels. 5. It was found that the percentage of yield for myofibril of duck meat was higher than that in the meat of tuna and camels. As to the percentage of yield for sarcoplasmic proteins of tuna meat, it was higher than that in the meat of duck and camels. 6. The highest percentage of moisture for myofibril proteins was in the meat of camels, and the lowest percentage of it was registered in myofibril proteins in tuna meat, whilst the highest percentage of moisture for sarcoplasmic proteins was registered in the meat of duck, and the lowest of it registered in sarcoplasmic proteins in tuna meat. 7. It was observed that the highest percentage of protein and fat for myofibril and sarcoplasmic proteins was registered in tuna meat, as the lowest percentage of protein and fat for myofibril and sarcoplasmic proteins were observed in duck meat. 8. The study came up with a result revealing that the percentage of ash in proteins of myofibril proteins for duck meat was higher than that in myofibril proteins for camels and tuna meat, whilst, the percentage of ash in sarcoplasmic proteins for camel meat was higher than that in sarcoplasmic proteins for duck and tuna meat. 9. Results showed that the highest concentration of sarcoplasmic proteins was in tuna meat, followed by duck meat, and the lowest concentration for these proteins was in camel meat. The values of proteins (myosin, tropomyosin, reticulin, and collagen) in camel meat, then followed by duck meat, whilst the lowest values for these proteins were in tuna meat.
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Abbaszadeh, M., K. Asakawa, H. Cinco-Ley, and N. Arihara. "Interference Testing in Reservoirs With Conductive Faults or Fractures." SPE Reservoir Evaluation & Engineering 3, no. 05 (October 1, 2000): 426–34. http://dx.doi.org/10.2118/66406-pa.
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Summary This paper addresses interference testing in reservoirs with conductive faults allowing fluid flow along and across the fault plane. An altered skin region around fault thrusts is also included. It is found that the classical line-source solution does not apply. When active and observation wells are located across a fault, the interference behavior resembles that of a hydraulically fractured well with bilinear flow characteristics. However, different flow regimes are developed on the pressure derivative when the well pairs are situated at the same side: initially, the basic line-source behavior; then, constant pressure effect from the fault represented by a negative unit-slope line; and, finally, bilinear flow. Interference type curves for various regions in the reservoir are developed and practical guidelines are provided for interpretation of these tests. Field data from an interference test in a faulted carbonate reservoir are analyzed and fault parameters are estimated. Introduction Faults are the most common form of heterogeneity in hydrocarbon reservoirs. The nature of fluid conductivity of faults, whether sealing or partially sealing or fully conductive, has a profound effect on oil and gas recovery from faulted reservoirs. While sealing faults block fluid and pressure communication with other regions of reservoir leading to reservoir compartmentalization, conductive faults can act as pressure support sources by allowing fluid transfer along and across their planes.1–3 Therefore, characterization of faults with respect to their conductivity behavior, fluid transmissibility potential, orientation, and geometrical attributes is important in many aspects of petroleum exploitation, field development, and production. Pressure-transient testing is a powerful tool for providing reliable and useful information about many reservoir characteristics. The use of single-well pressure-transient tests in delineating faults is abundant in the literature. The simplest of the models address estimation of distance to sealing faults.4–8 Cinco-Ley et al.9 considered an infinite conductivity fault or fracture and derived analytical solutions based on the concept of source functions. The first attempt to represent a fault as a partial barrier was introduced by Stewart10 who numerically modeled the fault zone as a vertical semipermeable barrier of negligible capacity. This model correctly imposed the linear flow pattern at the fault plane. Yaxley11 obtained analytical solutions for transient pressures by considering the fault as a semi-impermeable linear discontinuity, a generalization of the Bixel et al.12 solution for reservoirs with linear discontinuities. Ambastha et al.13 analytically modeled a partially communicating fault as a thin skin region in the reservoir. The work of Abbaszadeh and Cinco-Ley14 provided a complete generalization where a fault (or a fracture) is viewed as a separate porous medium with two-dimensional flow occurring inside the fault plane. That work showed that it was possible to estimate reservoir properties, fault conductivity, fault skin factor, and distance to the fault from a pressure-buildup or a pressure-drawdown test. Although the solutions provided by Abbaszadeh and Cinco-Ley14 are general enough to cover transient pressure distribution in a faulted reservoir, multiple-well tests of interference or pulse tests were not addressed specifically. Because the compounding experience with interference tests has demonstrated their usefulness in identifying interwell heterogeneity and other reservoir characteristics,15 their application to reservoirs with conductive faults is warranted. This paper studies interference tests when an observation well is located at either side of an infinitely long conductive fault. Various flow regimes and transient behavior occurring in such tests are discussed. Because multiple parameters are involved and the characteristics of pressure response are often complex, guidelines are provided to help in the interpretation of interference tests. Type curves specific to the right side and left side of a fault are developed and used to interpret field data from an interference test near a conductive fault. These type curves and the interpretation procedure are discussed. Assumptions and Method of Solution We consider a homogeneous isotropic reservoir of uniform thickness containing slightly compressible single-phase fluid. There is a fault of infinite extent which separates the reservoir into two regions with transmissibility and diffusivity of (?1,?1) and (?2, ?2). This situation can be created when a reservoir rock is juxtaposed against a formation with different properties. The fault plane itself has permeability kf width wf and a damaged region of permeability ka whose extent is wa as seen in Fig. 1. The active well is located at the left side of the fault, and the observation well can be situated at either side. The solution for pressure transients in this system is obtained by decoupling the reservoir and fault systems, and solving for the diffusivity equations in each system with flux distributions at the fault plane as unknowns. The flux distributions are then obtained by coupling the reservoir and fault solutions at the fault plane. The derivations are done in transformed Laplace space and the method of images along with the Green's function formulation are used. The details are given in Ref. 14. Briefly, p L D ( x D , y D , t D f ) = ∫ 0 t D f ∫ 0 ∞ u f L D ( y D ′ , τ D ) t D f − τ D { e x p [ − ( 1 − x D ) 2 + ( y D + y D ′ ) 2 4 ( t D f − τ D ) ] + e x p [ − ( 1 − x D ) 2 + ( y D − y D ′ ) 2 4 ( t D f − τ D ) ] } d y D ′ d τ D − 1 2 E i [ − x D 2 + y D 2 4 t D f ] − 1 2 E i [ − ( 2 − x D ) 2 + y D 2 4 t D f ] ( 1 ) and p R D ( x D , y D , t D f ) = M ∫ 0 t D f ∫ 0 ∞ u f R D ( y D ′ , τ D ) t D f − τ D { e x p [ − F η ( x D − 1 ) 2 + ( y D + y D ′ ) 2 4 ( t D f − τ D ) ] + e x p [ − F η ( x D − 1 ) 2 + ( y D − y D ′ ) 2 4 ( t D f − τ D ) ] } d y D ′ d τ D . ( 2 )
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Jha, Sudhanshu Kumar, Shiv Prakash, Rajkumar Singh Rathore, Mufti Mahmud, Omprakash Kaiwartya, and Jaime Lloret. "Quality-of-Service-Centric Design and Analysis of Unmanned Aerial Vehicles." Sensors 22, no. 15 (July 22, 2022): 5477. http://dx.doi.org/10.3390/s22155477.
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Recent years have witnessed rapid development and great indignation burgeoning in the unmanned aerial vehicles (UAV) field. This growth of UAV-related research contributes to several challenges, including inter-communication from vehicle to vehicle, transportation coverage, network information gathering, network interworking effectiveness, etc. Due to ease of usage, UAVs have found novel applications in various areas such as agriculture, defence, security, medicine, and observation for traffic-monitoring applications. This paper presents an innovative drone system by designing and developing a blended-wing-body (BWB)-based configuration for next-generation drone use cases. The proposed method has several benefits, including a very low interference drag, evenly distributed load inside the body, and less radar signature compared to the state-of-the-art configurations. During the entire procedure, a standard design approach was followed to optimise the BWB framework for next-generation use cases by considering the typically associated parameters such as vertical take-off and landing and drag and stability of the BWB. Extensive simulation experiments were performed to carry out a performance analysis of the proposed model in a software-based environment. To further confirm that the model design of the BWB-UAV is fit to execute the targeted missions, the real-time working environments were tested through advanced numerical simulation and focused on avoiding cost and unwanted wastages. To enhance the trustworthiness of this said computational fluid dynamics (CFD) analysis, grid convergence test-based validation was also conducted. Two different grid convergence tests were conducted on the induced velocity of the Version I UAV and equivalent stress of the Version II UAV. Finite element analysis-based computations were involved in estimating structural outcomes. Finally, the mesh quality was obtained as 0.984 out of 1. The proposed model is very cost-effective for performing a different kind of manoeuvring activities with the help of its unique design at reasonable mobility speed and hence can be modelled for high-speed-based complex next-generation use cases.
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Vuyyuru, Nagi Reddy, A. Malleswara Reddy, B. Ramadevi, Y. Ravindra Kumar, and B. Janaki Durga Prasad. "A Simple, Specific, Mass Compatible and Validated Gas Chromatographic Method for the Estimation of Piperidine-3-amine Content in Linagliptin Finished and Stability Samples without Derivatization." Asian Journal of Chemistry 32, no. 10 (2020): 2567–72. http://dx.doi.org/10.14233/ajchem.2020.22817.
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A new simple, selective, highly sensitive, specific (stability indicating), robust, rugged and mass compatible gas chromatographic method and sample with direct injection-mode was developed for the quantitative determination of amino-3-piperidine (3-aminopiperidine, 3-AMP) in linagliptin. As the CAD-LC method did not proved for specificity and pre-derivitizations are challenging task for quality control (QC), a simple GC method has been developed. Compared to LC-CAD method, which is not proved for specificity and pre-column derivitization methods having the limitations to analyze the reaction monitoring in-process samples and degradation samples, the present method is selective, simple, cost effective, QC friendly, widely available GC technique with direct injection and high in sensitivity. Also this method is mass compatible, specificity proved by forced degradation, method was validated as per ICH guidelines. Mass balance was proved by analyzing the stressed samples for net degradation by HPLC and assay by HPLC methods. This GC method also provides an advantage to analyze the in-process samples to monitor the progress of the synthetic process, where the reaction monitoring samples are unpurified or non-isolated samples and contains many process related impurities (reference) and solvents, which will have interference with 3-AMP in LC-CAD and pre-column derivitization methods. This method involves simple sample preparation process and direct injection with GC-FID technique. Hence, this method can be used to analyze the finished product samples, degradation samples, stability samples and reaction monitoring samples. The method was developed with widely available GC column (diphenyl dimethyl polysiloxane as stationary phase, 30 m length, 0.53 mm internal diameter & 5.0 μm thickness), helium as carries gas, FID detector set at 240 ºC, column oven starts at 200 ºC and starts increases after 2 min with 20 ºC/min and holds up to 11 min, which will ensure the column bake. The solvents used for the process were well separated from 3-AMP peak. Mass balance was reported > 99%. The limit of quantification and limit of detection values for 3-AMP were 0.002% (0.4 μg/mL) and 0.007% (1.4 μg/mL) of targeted concentration (20 mg/mL), respectively. The method was precise at LOQ and at specification level with %RSD values 2.8 and 4.7, respectively. Linearity was established in the range of 0.0014 mg/mL (LOQ) to 0.045 mg/mL for 3-AMP with correlation coefficient (r2 > 0.9995). The percentage recoveries were obtained between 99.9% and 104.4%. The range of the method was established from LOQ (0.0014 mg/mL) to 150% (0.045 mg/mL) of the specification targeted limit of 0.15% (0.03 mg/mL). The standard and spiked sample solutions were studied up to 2 days and are stable at room temperature. The forced degradation studies were performed by using HCl, NaOH, H2O2 thermal, UV radiation and water. A mild degradation bout 0.25% was observed in base degradation condition, which was confirmed with mass number by GC-MS analysis. Validation parameters were evaluated according to the International Conference on Harmonization (ICH) Q2 guidelines.
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Chu, Wei-Chun, C. H. Fleming, and K. M. Carroll. "Determination of Original Gas in Place in Ballycotton, Offshore Ireland." SPE Reservoir Evaluation & Engineering 4, no. 01 (February 1, 2001): 11–15. http://dx.doi.org/10.2118/69735-pa.
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Summary Early, accurate determination of original gas in place (OGIP) is highly desirable for planning the future of a gas field. This paper presents a case history of an offshore gas field, using a recently developed pressure-rate-time analysis technique to illustrate the effectiveness of the method. In addition, this paper demonstrates the great benefit of permanently installed pressure gauges in obtaining consistent pressure and flow-rate data for the effective use of the technique for subsea completed wells. Introduction Early, accurate determination of OGIP is always desirable in a new gas field development, as this information is critical in decision making for reservoir management. For example, the optimum number of wells or the need for compression at the surface depends on OGIP. In addition, the operator is often required to project production rates in order to secure a gas sales contract. These decisions are typically made early in the life of a field, and erroneous estimates of OGIP can lead to poor decisions that may be costly or impossible to correct later in the field life. Various reserve estimation methods have been published in the literature,1 ranging from basic material-balance calculation to decline-curve analysis. Recently, Agarwal et al.2 presented new production decline curves for analyzing well production data by combining type-curve and decline-curve analysis concepts. In this report, we applied Agarwal et al.'s analysis techniques2 to pressure and rate measurements over a period of approximately 3,000 days at Ballycotton. Subsequent analysis of short-term performance data showed that an accurate estimate of OGIP was established from the first 6 months of production. The results were confirmed independently using reservoir simulation while examining the effects of water influx and production interference from Kinsale Head. Background Information Geologic Setting and Field Description. The Ballycotton gas field lies approximately 25 miles off the coast of Cork, Ireland in the North Celtic Sea basin. It was discovered in March 1989 and has been produced from Well 48/20-2 since July 1991 as a satellite field by means of a single subsea well completion and tieback to the Kinsale Head's Bravo platform. A location map is shown in Fig. 1. The ‘A’ Sand producing interval in Ballycotton and Kinsale Head is the focus of this paper. This sand extends from Kinsale Head gas field in the south to Ballycotton gas field in the north, thus connecting the two fields by a common aquifer. Ref. 3 gives a comprehensive geologic description of the region. The Kinsale Head gas field was discovered in 1971 and was placed on production in October 1978. The existence of gas-processing facilities at Kinsale Head made it commercially feasible to produce Ballycotton, which at the time of discovery was thought to contain 80 Bcf from a volumetric study. About 760 Bcf of gas were produced from the ‘A’ Sand of Kinsale Head by the time Ballycotton was placed on-line. Immediately after Ballycotton was put on production in July 1991, an attempt was made to estimate OGIP from the initial production data. Assuming hydrostatic equilibrium between the two fields, the initial pressure at Ballycotton was estimated from 1978 pressures at Kinsale Head gas field. This pressure, compared to the Ballycotton pressure measured immediately before commercial production, shows a pressure loss of 50 psi, thus reflecting interference resulting from production at Kinsale Head. Pressure interference is transmitted through the common aquifer between Kinsale Head and Ballycotton. Because the complexities of water influx and interference cannot be easily accounted for in a gas/water system, it was difficult to provide an OGIP estimate from the simple material balance. However, a numerical simulation study of a single well in an edge-waterdrive gas reservoir indicated that it was possible to estimate an OGIP from the drawdown data in the early life of a reservoir before the influence of water influx becomes dominant.4 Later, a full-field model was set up to examine the strength of water influx. This will be discussed in the simulation study section. The Ballycotton completion was the first subsea development in the Celtic Sea. A permanent gauge was installed on the subsea tree in 285 ft of water to monitor wellhead pressure (WHP). From the corresponding gas rate and measured WHP, we calculated bottomhole pressure (BHP) with the Cullender and Smith method.5Fig. 2 shows a graph of calculated flowing BHP and gas-flow rate between July 1991 and September 1999. Both pressure and rate are monotonically decreasing. Our goal was to determine the OGIP from the production-performance data with both flowing BHP and gas-flow rate. Historical Development of Analysis Technique. Analysis of the gas-production performance data involves nonlinear effects of gas physical properties and variable-rate production mode during boundary-dominated flow. Recognizing that the partial-differential equation governing the flow of gases is nonlinear, researchers have focused on correlating the gas-flow solutions with the appropriate liquid-flow solutions.6 Gradually, a new time function was developed to convert the production data of either constant rate or constant BHP into a form that could be analyzed with constant-rate liquid solutions. This section presents the historical development of these techniques. To analyze monotonically declining rate and pressure data to estimate reserves, pseudosteady-state flow must be established in the long-term performance data. Using the principle of superposition, Blasingame and Lee7 showed that equivalent time, te, defined as cumulative production divided by the corresponding flow rate, could be applied to a liquid system in pseudosteady-state flow. This suggests that long-term performance data can be used to estimate pore volume by plotting the pressure difference (?=pi-pwf) normalized by the corresponding flow rate vs. te. The slope of the graph is used to calculate reserves for a slightly compressible liquid case. Al-Hussainy et al.8 showed that during the boundary-dominated flow period there are considerable differences between the liquid and gas solutions. It is clear that nonlinear effects become dominant during the pseudosteady-state flow period, when the wellbore pressure depends on the physical properties of the produced gas and the flow rate.
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Kanai, Satoshi, and Jouke C. Verlinden. "Special Issue on Augmented Prototyping and Fabrication for Advanced Product Design and Manufacturing." International Journal of Automation Technology 13, no. 4 (July 5, 2019): 451–52. http://dx.doi.org/10.20965/ijat.2019.p0451.
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“Don’t automate, augment!” This is the takeaway of the seminal book on the future of work by Davenport and Kirby.*1 The emergence of cyber-physical systems makes radical new products and systems possible and challenges the role of humankind. Throughout the design, manufacturing, use, maintenance, and end-of-life stages, digital aspects (sensing, inferencing, connecting) influence the physical (digital fabrication, robotics) and vice versa. A key takeaway is that such innovations can augment human capabilities to extend our mental and physical skills with computational and robotic support – a notion called “augmented well-being.” Furthermore, agile development methods, complemented by mixed-reality systems and 3D-printing systems, enable us to create and adapt such systems on the fly, with almost instant turnaround times. Following this line of thought, our special issue is entitled “Augmented Prototyping and Fabrication for Advanced Product Design and Manufacturing.” Heavily inspired by the framework of Prof. Jun Rekimoto’s Augmented Human framework,*2 we can discern two orthogonal axes: cognitive versus physical and reflective versus active. As depicted in Fig. 1, this creates four different quadrants with important scientific domains that need to be juxtaposed. The contributions in this special issue are valuable steps towards this concept and are briefly discussed below. AR/VR To drive AR to the next level, robust tracking and tracing techniques are essential. The paper by Sumiyoshi et al. presents a new algorithm for object recognition and pose estimation in a strongly cluttered environment. As an example of how AR/VR can reshape human skills training, the development report of Komizunai et al. demonstrates an endotracheal suctioning simulator that establishes an optimized, spatial display with projector-based AR. Robotics/Cyborg Shor et al. present an augmentation display that uses haptics to go beyond the visual senses. The display has all the elements of a robotic system and is directly coupled to the human hand. In a completely different way, the article by Mitani et al. presents a development in soft robotics: a tongue simulator development (smart sensing and production of soft material), with a detailed account of the production and the technical performance. Finally, to consider novel human-robot interaction, human body tracking is essential. The system presented by Maruyama et al. introduces human motion capture based on IME, in this case the motion of cycling. Co-making Augmented well-being has to consider human-centered design and new collaborative environments where the stakeholders involved in whole product life-cycle work together to deliver better solutions. Inoue et al. propose a generalized decision-making scheme for universal design which considers anthropometric diversity. In the paper by Tanaka et al., paper inspection documents are electronically superimposed on 3D design models to enable design-inspection collaboration and more reliable maintenance activities for large-scale infrastructures. Artificial Intelligence Nakamura et al. propose an optimization-based search for interference-free paths and the poses of equipment in cluttered indoor environments, captured by interactive RGBD scans. AR-based guidance is provided to the user. Finally, the editors would like to express their gratitude to the authors for their exceptional contributions and to the anonymous reviewers for their devoted work. We expect that this special issue will encourage a new departure for research on augmented prototyping for product design and manufacturing. *1 T. H. Davenport and J. Kirby, “Only Humans Need Apply: Winners and Losers in the Age of Smart Machines,” Harper Business, 2016. *2 https://lab.rekimoto.org/about/ [Accessed June 21, 2019]
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Hameed, Ahmed A., and Kamal M. Abood. "A Model of Sky Temperature Estimation at 1.42 GHz using University of Baghdad’s Radio Telescope." Iraqi Journal of Science, December 24, 2021, 4537–44. http://dx.doi.org/10.24996/ijs.2021.62.11(si).33.
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The objective of this study is to select a suitable observing region at Baghdad location (44o 22' 48", 33o 16' 30") with low interference that may affect frequency of 1.42 GHz. Baghdad University Radio Telescope (BURT) is used in this study to determine a convenient region for observation in Baghdad sky. Different azimuths and elevations were chosen at different observations time. The results of this study showed that the best observations regions were located at azimuth (120o-160o) and (210o-260o). These regions included less sky temperature and estimated to be (42.8 to 163) K. The sky temperature model could be represented as a polynomial of third degree that could fit the behavior of the observation points.
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Hanne, Aylin A., Jan Tünnermann, and Anna Schubö. "Target templates and the time course of distractor location learning." Scientific Reports 13, no. 1 (January 30, 2023). http://dx.doi.org/10.1038/s41598-022-25816-9.
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AbstractWhen searching for a shape target, colour distractors typically capture our attention. Capture is smaller when observers search for a fixed target that allows for a feature-specific target template compared to a varying shape singleton target. Capture is also reduced when observers learn to predict the likely distractor location. We investigated how the precision of the target template modulates distractor location learning in an additional singleton search task. As observers are less prone to capture with a feature-specific target, we assumed that distractor location learning is less beneficial and therefore less pronounced than with a mixed-feature target. Hierarchical Bayesian parameter estimation was used to fit fine-grained distractor location learning curves. A model-based analysis of the time course of distractor location learning revealed an effect on the asymptotic performance level: when searching for a fixed-feature target, the asymptotic distractor cost indicated smaller distractor interference than with a mixed-feature target. Although interference was reduced for distractors at the high-probability location in both tasks, asymptotic distractor suppression was less pronounced with fixed-feature compared to mixed-feature targets. We conclude that with a more precise target template less distractor location learning is required, likely because the distractor dimension is down-weighted and its salience signal reduced.
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Zhao, Nan, Yubo Wang, Xiaoke Tang, Jie Gan, Xu Zhao, and Yubing Zhang. "The influence of ISI on channel estimation and optimized channel estimation in PSK-chirp system." Journal of Intelligent & Fuzzy Systems, February 1, 2021, 1–10. http://dx.doi.org/10.3233/jifs-189697.
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Due to the influence of filters and multipath channels, the received signal of the current symbol will be affected by the interference of the previous symbol and the next symbol, the interference will reduce the performance of channel estimation, especially when the SF is relatively low, which will affect the system throughput rate. In this paper, based on BPSK chirp spread spectrum modulation system, we first describe the channel estimation of matched filtering and FFT, and derive the influence of ISI on the channel estimation of the current pilot symbol. Then we proposed the improved channel estimation based on the estimated time delay spread and transmitted signals. Finally, we simulate the MSE performance of channel estimation under different channels and different transmitted signals. The simulation results show that the MSE performance of the improved channel estimation can be improved under different channel when the SF is low, and higher throughput can be obtained.