Journal articles on the topic 'High thickness variations'
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1
Stockert, Sven, Matthias Wehr, Johannes Lohmar, Gerhard Hirt, and Dirk Abel. "Development of a Laser Triangulation Gauge for High Precision Strip Thickness Control." Advanced Materials Research 1140 (August 2016): 107–14. http://dx.doi.org/10.4028/www.scientific.net/amr.1140.107.
Abstract:
Almost all metal strips with thicknesses of < 2 mm are produced by cold rolling. Thickness variations of cold rolled strips are caused by various factors like fluctuation in strength of the material, the eccentricity of the rolls or thickness variation of the incoming strip. As the demands concerning the thickness variation are ever increasing the Institute of Automatic Control and the Institute of Metal Forming aim at reducing the thickness tolerance of thin, cold-rolled steel and copper strips to 1 μm. As high frequency disturbances are expected, it is assumed that this goal can only be achieved by using a predictive controller in combination with a high precision strip thickness gauge and, for roll adjustment, a piezoelectric actuator in addition to the existing electromechanical actuator. The objective of this work is the constructive implementation and the testing of a thickness gauge based on laser triangulation. The gauge includes guide rollers to prevent strip vibration, a C-frame to allow an inline calibration and mechanical adjustment of the measuring range so that even flexible strip thicknesses can be measured. The designed gauge showed a high repeat accuracy of 0.4 μm for two different metal strips. Furthermore the gauge was used to investigate the dynamics of the thickness change of a steel strip at maximum rolling speed of 5 m/s using a Fourier transformation. This frequency analysis supports the need for a piezoelectric actuator that can also subsequently be dimensioned based on the obtained frequency data.
2
Feng, Jian, Yuqiang Zhang, Na Xu, Bo Chen, Tong Xu, Zhensen Wu, Zhongxin Deng, et al. "Statistical Study of the Ionospheric Slab Thickness at Yakutsk High-Latitude Station." Remote Sensing 14, no. 21 (October 24, 2022): 5309. http://dx.doi.org/10.3390/rs14215309.
Abstract:
The ionospheric equivalent slab thickness (EST, also named τ) is defined as the ratio of the total electron content (TEC) to the F2-layer peak electron density (NmF2), and it is a significant parameter representative of the ionosphere. This paper presents a comprehensive statistical study of the ionospheric slab thickness at Yakutsk, located at the high latitude of East Asia, using the GPS-TEC and ionosonde NmF2 data for the years 2010–2017. The results show that the τ has different diurnal and seasonal variations in high- and low-solar-activity years, and the τ is greatest in the winter, followed by the equinox, and it is smallest in the summer in both high- and low-solar-activity years, except during the noontime of low-solar-activity years. Specifically, the τ in inter of high-solar-activity year shows an approximate single peak pattern with the peak around noon, while it displays a double-peak pattern with the pre-sunrise and sunset peaks in winter of the low-solar-activity years. Moreover, the τ in the summer and equinox have smaller diurnal variations, and there are peaks with different magnitudes during the sunrise and post-sunset periods. The mainly diurnal variation of τ in different seasons of high- and low-solar-activity years can be explained within the framework of relative variation of TEC and NmF2 during the corresponding period. By defining the disturbance index (DI), which can visually assess the relationship between instantaneous values and the median, we found that the geomagnetic storm would enhance the τ at Yakutsk. An example on 7 June 2013 is also presented to analyze the physical mechanism. It should be due to the intense particle precipitation and expanded plasma convection electric field during the storm at high-latitude Yakutsk station. The results would improve the current understanding of climatological and storm-time behavior of τ at high latitudes in East Asia.
3
Rizqi Widyanti, Elvira, Choirul Anam, Eko Hidayanto, Ariij Naufal, and Mohammad Haekal. "An evaluation of automated measurement of slice sensitivity profile of computed tomography image: field of view variations." Indonesian Journal of Electrical Engineering and Computer Science 29, no. 3 (March 1, 2023): 1430. http://dx.doi.org/10.11591/ijeecs.v29.i3.pp1430-1437.
Abstract:
This study aims to evaluate the automated measurement of slice sensitivity profile (SSP) on the American Association of Physicists in Medicine (AAPM) computed tomography (CT) performance phantom for variations of slice thickness and field of view (FOV). The AAPM CT performance phantom was scanned using a Philips MRC 880 CT Scanner for variations of slice thickness and FOV. The slice thickness values were 1, 3, and 5 mm. The FOV values were 240, 300, 340, 400, and 440 mm. The automated SSPs and their fullwidth at half maximums (FWHMs) were automatically measured from the middle stair object of the phantom. To validate the automated measurement results, the FWHM values of SSPs obtained were compared to those from manual measurements. The differences between FWHMs from automated measurements and set slice thicknesses are less than 0.3 mm, while the differences between FWHMs from automated and manual measurements are less than 0.2 mm. The results from automated measurements are closer to the set slice thickness than those from manual measurements. This automated SSP measurement provides high accuracy and precision for both the slice thickness and the FOV variations.
4
Garbe, S., Dorte Juul Jensen, Henning Friis Poulsen, N. C. Krieger Lassen, and Dierk Raabe. "Through-Thickness Texture Variations Determined Non-Destructively by High Energy Synchrotron Radiation." Materials Science Forum 273-275 (February 1998): 271–76. http://dx.doi.org/10.4028/www.scientific.net/msf.273-275.271.
5
Morina, Edona, Marius Dotter, Christoph Döpke, Ilda Kola, Tatjana Spahiu, and Andrea Ehrmann. "Homogeneity of Needleless Electrospun Nanofiber Mats." Nanomaterials 13, no. 18 (September 6, 2023): 2507. http://dx.doi.org/10.3390/nano13182507.
Abstract:
Nanofiber mats can be electrospun by different techniques, usually subdivided into needle-based and needleless. The latter allow for producing large-area nanofiber mats, e.g., with a width of 50 cm and lengths of several meters, if electrospinning proceeds for several hours, depending on the required thickness. Even spinning smaller samples, however, raises the question of homogeneity, especially if defined mechanical properties or a defined thickness is required, e.g., for filtration purposes. Very often, only the inner parts of such electrospun nanofiber mats are used to avoid too high variation of the nanofiber mat thickness. For this study, we used wire-based electrospinning to prepare nanofiber mats with slightly varying spinning parameters. We report investigations of the thickness and mass per unit area, measured on different positions of needleless electrospun nanofiber mats. Martindale abrasion tests on different positions are added as a measure of the mechanical properties. All nanofiber mats show unexpectedly strong variations of thickness, mass per unit area, and porosity, as calculated from the apparent density of the membranes. The thickness especially varied by nearly one order of magnitude within one sample, while the apparent density, as the most uniform parameter, still showed variations by more than a factor of two within one sample. This shows that even for apparently highly homogeneous areas of such nanofiber mats, variations cannot be neglected for all potential applications.
6
George, Daniel, Stéphane Pallu, Céline Bourzac, Rkia Wazzani, Rachele Allena, Yves Rémond, and Hugues Portier. "Prediction of Cortical Bone Thickness Variations in the Tibial Diaphysis of Running Rats." Life 12, no. 2 (February 3, 2022): 233. http://dx.doi.org/10.3390/life12020233.
Abstract:
A cell-mechanobiological model is used for the prediction of bone density variation in rat tibiae under medium and high mechanical loads. The proposed theoretical-numerical model has only four parameters that need to be identified experimentally. It was used on three groups of male Wistar rats under sedentary, moderate intermittent and continuous running scenarios over an eight week period. The theoretical numerical model was able to predict an increase in bone density under intermittent running (medium intensity mechanical load) and a decrease of bone density under continuous running (higher intensity mechanical load). The numerical predictions were well correlated with the experimental observations of cortical bone thickness variations, and the experimental results of cell activity enabled us to validate the numerical results predictions. The proposed model shows a good capacity to predict bone density variation through medium and high mechanical loads. The mechanobiological balance between osteoblast and osteoclast activity seems to be validated and a foreseen prediction of bone density is made available.
7
Zhang, Qianwen, Xue Chu, Zhipeng Gao, Yulong Ding, Feng Que, Zishan Ahmad, Fen Yu, Muthusamy Ramakrishnan, and Qiang Wei. "Culm Morphological Analysis in Moso Bamboo Reveals the Negative Regulation of Internode Diameter and Thickness by Monthly Precipitation." Plants 13, no. 11 (May 28, 2024): 1484. http://dx.doi.org/10.3390/plants13111484.
Abstract:
The neglect of Moso bamboo’s phenotype variations hinders its broader utilization, despite its high economic value globally. Thus, this study investigated the morphological variations of 16 Moso bamboo populations. The analysis revealed the culm heights ranging from 9.67 m to 17.5 m, with average heights under the first branch ranging from 4.91 m to 7.67 m. The total internode numbers under the first branch varied from 17 to 36, with internode lengths spanning 2.9 cm to 46.4 cm, diameters ranging from 5.10 cm to 17.2 cm, and wall thicknesses from 3.20 mm to 33.3 mm, indicating distinct attributes among the populations. Furthermore, strong positive correlations were observed between the internode diameter, thickness, length, and volume. The coefficient of variation of height under the first branch showed strong positive correlations with several parameters, indicating variability in their contribution to the total culm height. A regression analysis revealed patterns of covariation among the culm parameters, highlighting their influence on the culm height and structural characteristics. Both the diameter and thickness significantly contribute to the internode volume and culm height, and the culm parameters tend to either increase or decrease together, influencing the culm height. Moreover, this study also identified a significant negative correlation between monthly precipitation and the internode diameter and thickness, especially during December and January, impacting the primary thickening growth and, consequently, the internode size.
8
Jalali-Vahid, D., Z. M. Jin, and D. Dowson. "Elastohydrodynamic lubrication analysis of hip implants with ultra high molecular weight polyethylene cups under transient conditions." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 217, no. 7 (July 1, 2003): 767–77. http://dx.doi.org/10.1243/095440603767764417.
Abstract:
The transient variation of both the load and speed experienced during walking in an elastohydrodynamic lubrication (EHL) analysis for artificial hip joints employing an ultra high molecular weight polyethylene (UHMWPE) acetabular cup against either a metallic or ceramic femoral head was considered in this study. A general numerical procedure to solve the transient EHL problem in spherical ball-in-socket coordinates, developed in a previous study by Jalali-Vahid and Jin in 2002, was applied under three specific conditions experienced during typical gait cycles, including speed reversal, a sudden load increase and a sudden load decrease. The predicted minimum film thickness was found to stay remarkably constant and similar to that prior to the change in either the load or the angular velocity, despite a large change in these operating conditions. This was attributed to the remarkably effective squeeze-film action of preserving and maintaining the lubricating film developed before the transient variations in either the load or speed. It is therefore possible to neglect the effect of these specific transient variations of load and speed under physiological walking conditions considered in the present study on the predicted film thickness in hip implants with UHMWPE cups.
9
Tu, Qianguang, Yun Zhao, Jing Guo, Chunmei Cheng, Liangliang Shi, Yunwei Yan, and Zengzhou Hao. "Spatial and Temporal Variations of Aerosol Optical Thickness over the China Seas from Himawari-8." Remote Sensing 13, no. 24 (December 14, 2021): 5082. http://dx.doi.org/10.3390/rs13245082.
Abstract:
Six years of hourly aerosol optical thickness (AOT) data retrieved from Himawari-8 were used to investigate the spatial and temporal variations, especially diurnal variations, of aerosols over the China Seas. First, the Himawari-8 AOT data were consistent with the AERONET measurements over most of the China Seas, except for some coastal regions. The spatial feature showed that AOT over high latitude seas was generally larger than over low latitude seas, and it is distributed in strips along the coastline and decreases gradually with increasing distance from the coastline. AOT undergoes diurnal variation as it decreases from 9:00 a.m. local time, reaching a minimum at noon, and then begins to increase in the afternoon. The percentage daily departure of AOT over the East China Seas generally ranged ±20%, increasing sharply in the afternoon; however, over the northern part of the South China Sea, daily departure reached a maximum of >40% at 4:00 p.m. The monthly variation in AOT showed a pronounced annual cycle. Seasonal variations of the spatial pattern showed that the largest AOT was usually observed in spring and varies in other seasons for different seas.
10
Zachariah, T., S. B. Rawal, S. N. Pramanik, M. V. Singh, S. Kishnani, H. Bharadwaj, and R. M. Rai. "Variations in skinfold thickness during de-acclimatisation and re-acclimatisation to high altitude." European Journal of Applied Physiology and Occupational Physiology 56, no. 5 (1987): 570–76. http://dx.doi.org/10.1007/bf00635372.
11
Goldshteyn, A. E., and Kh Kh Abakumov. "Mitigation of the effect of variations in the electrical conductivity of the material via two-frequency eddy current testing of the thickness of the electrically conductive wall under significantly varying influence parameters." Bulletin of the Karaganda University. "Physics" Series 109, no. 2 (March 30, 2023): 71–79. http://dx.doi.org/10.31489/2023ph1/71-79.
Abstract:
The paper analyzes feasibility of the two-frequency eddy current method for measuring the thickness of an electrically conductive wall under significantly varying test and influence parameters of the test object — the lift-off between the eddy current probe and the test object surface, and the electrical conductivity of the material. An analytical solution was used to determine the dependence of the two-frequency signal of the surface eddy current probe on the influence parameters of the test object. The informative parameters used to simultaneously mitigate the effect of the two influence parameters were the amplitude of the added high-frequency voltage to determine the lift-off, the phase of the added low-frequency voltage to determine the wall thickness, and the phase of the added high-frequency voltage to suppress variations in the electrical conductivity of the material. The calculated dependences of the informative parameters on the test and influence parameters were analyzed. The use of nonlinear functions of the inverse transformation of the informative parameter into the test parameter was shown to efficiently mitigate the effect of variations in the lift-off on measurement results. A method to suppress variations in the electrical conductivity of the test object material is proposed. It implies the correction of the phase of the added low-frequency voltage by the correction value calculated from the parameters of the lift-off and wall thickness, and high-frequency phase variation caused by varying the electrical conductivity of the material.
12
Ghosh, M. K., R. K. Pandey, and P. Singh. "Thermal effect on the film thickness in high-speed lubricated cold rolling of a strip—an inlet zone analysis." Proceedings of the Institution of Mechanical Engineers, Part J: Journal of Engineering Tribology 217, no. 2 (February 1, 2003): 155–66. http://dx.doi.org/10.1243/13506500360603589.
Abstract:
A thermal analysis of hydrodynamic lubrication of high-speed cold rolling of strips in the inlet zone has been made to estimate the film thickness in the contact region. The piezoviscous effect, which would be significant in the case of heavy-duty rolling when a large reduction in the thickness of the strip takes place during the rolling process, has been incorporated using Roelands' viscosity model. The generalized Reynolds equation in the inlet zone has been solved using the finite difference method to determine the pressure distribution. Temperature variations across the film have been expressed using Legendre's polynomial at Lobatto points while solving the energy equation. Temperature variations along the film were determined using the finite difference method by solving the energy equation. The results for the film thickness-temperature profile in the inlet zone have been estimated for high-speed rolling of the strip (up to 50m/s) with and without sliding for heavy reduction in thickness of the strip. Significant reduction in the film thickness due to the thermal effect has been found.
13
Chen, Wei, Yubo Guan, Guanghui He, Zhiwei Li, Hui Song, Shiyong Xie, and Quanhong Han. "Aqueous Levels of Pigment Epithelium-Derived Factor and Macular Choroidal Thickness in High Myopia." Journal of Ophthalmology 2015 (2015): 1–6. http://dx.doi.org/10.1155/2015/731461.
Abstract:
Purpose. To investigate the correlation between aqueous and serum levels of pigment epithelium-derived factor (PEDF) and macular choroidal thickness in high myopia patients, both with and without choroidal neovascularization (CNV).Methods. Serum and aqueous levels of PEDF were measured by enzyme-linked immunosorbent assay in 36 high myopia patients (36 eyes) with no CNV (non-CNV group), 14 high myopia patients (14 eyes) with CNV (CNV group), and 42 nonmyopia patients (42 eyes) (control group). Macular choroidal thickness was measured by enhanced-depth imaging optical coherence tomography.Results. Aqueous levels of PEDF were significantly higher in CNV group compared with non-CNV (P<0.001) and control (P<0.001) groups. Macular choroidal thicknesses were significantly decreased in the non-CNV and CNV groups compared with the control (P<0.001) group. A statistically significant difference (P=0.012) was found between the CNV and non-CNV groups. There was a positive correlation between aqueous PEDF and macular choroidal thickness in the non-CNV group (P=0.005), but no correlation with the CNV group. No correlation between serum PEDF and macular choroidal thickness was detected in the three groups.Conclusion. Variations in aqueous PEDF levels coincide with changes in macular choroidal thickness in high myopia patients with no CNV, while no such relationship exists in high myopia patients with CNV.
14
Muadifah, Afidatul, Arif Santoso, Khoirul Ngibad, Rahma Diyan Martha, and Siti Nurriyatul Kholifah. "Calcium Reduction Using Variations of Thickness and Retention Time of Cocoa Shell Activated Carbon." CHEMPUBLISH JOURNAL 7, no. 1 (July 30, 2023): 42–53. http://dx.doi.org/10.22437/chp.v7i1.24768.
Abstract:
High levels of hardness can lead to increased cases of kidney stones. Hardness levels can be reduced by using activated carbon from the cocoa rind as an adsorbent. The purpose of this research was to determine the variation of activated carbon thickness and optimum retention time in reducing the calcium content of dug well water, to determine the percent decrease in calcium ion levels at the optimum variation, and to determine the significance of the difference in the decreased in calcium levels between the treatment groups. The research method used the principle of adsorption of activated carbon from cocoa shells to calcium ions, which are activated by KOH. There were ten treatment samples with different variations of activated carbon thickness and retention time. The results showed that the thickness of activated carbon of 60 cm with a retention time of 50 minutes had the optimum ability to reduce the calcium content of dug well water. The percentage decrease in calcium levels reached 89,041 % with a decreased concentration of 234 ppm. The result of the statistical test showed a significance value of 0,05. The conclusion of the research is that activated carbon of cocoa shells can reduce calcium levels to the levels of soft water hardness, with variations in activated carbon thickness and retention time having a significant effect.
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Rathore, Rituraj S., and Viranjay M. Srivastava. "(Digital Presentation) Influence of Fin Width Modulation on Nanoscale FinFET." ECS Meeting Abstracts MA2022-02, no. 36 (October 9, 2022): 1326. http://dx.doi.org/10.1149/ma2022-02361326mtgabs.
Abstract:
ABSTRACT In the present research work, the influence of Fin width thickness variation on the electrical performance parameters have been performed for the FinFET device. Various Fin angle (i.e., θ) have been considered to analyze the effect of Fin thickness variations. All the analyzed results have been compared with the ideal FinFET (i.e., θ = 0) device to observe the effect of angle variation on threshold voltage (VTH), Transconductance (gm), Gate current (IG) and Drain Induced Barrier Lowering (DIBL). In addition, the impact of Fin width thickness variations has been used to realize the inverter Voltage Transfer Characteristics (VTC). The characteristics comparison reveals that including the effect of Fin width improves the device performance of FinFET devices. INTRODUCTION The FinFET device has been considered as a future candidate for VLSI circuit design and manufacturing. Compared with planar technology, the FinFET device shows reduced Short Channel Effects (SCEs) and improved electrostatic control. However, device variability poses a severe threat to downscaling FinFET dimensions in the nanoscale regime because non-uniformity has a significant influence on short-channel devices [1, 2]. In the fabrication of FinFET devices, the effect of the nonrectangular Fin shape must be carefully considered because the Fin thickness of the fabricated FinFET differs from the ideal shape. It is found that it is difficult to achieve a perfect rectangular Fin shape due to Line Edge Roughness (LER) and Line Width Roughness (LWR) [3]. In previous research works, authors considered the variations introduced in the vertical direction of the Fin while ignoring the fact that Fin width fluctuates in the lateral direction too [4]. This lateral Fin fluctuation introduces significant errors during performance parameter analysis. Therefore, this present research work focused on fluctuations in the Fin in the lateral direction. Here, the effects of non-uniformity on electrical performance parameters such as VTH, gm, IG and DIBL have been analyzed and compared with the ideal FinFET device. Furthermore, the impact of these variations is incorporated into the realization of inverter VTC characteristic. DEVICE DESIGN AND RESULT ANALYSIS Fig. 1(a) shows the full 3D view of the FinFET device. The doping concentration of the Source/Drain (S/D) region is maintained at 1×1020 cm-3 . Here, channel thickness (Tsi ) and gate oxide thickness (tox ) are 8 nm and 1 nm, respectively. Titanium Nitride (TiN) metal has been employed as the gate electrode because TiN shows low resistivity, high melting, thermal stability, and compatibility with the standard CMOS process [5]. To analyze the effects of fin width variation on the performance parameters of FinFET, the non-uniformity has been shown in Fig. 1(b). Here, Tsi fluctuations are approximated as a linear slope, making an angle (θ) to X-axis in the range of -70 to 70 to exaggerate the width variation effects. A Positive angle means the drain area is more significant compared to the source area and vice versa. Fig. 2 displays the VTH and DIBL variations against the Fin width variation. It has been realized that for Fin thickness variation from -70 to +70 there is a shift in threshold voltage (VTH ) of 6.12% and 4.08%, respectively. However, it is also observed that the non-uniform Fin width improves the DIBL for the FinFET device. This is due to the modulation of the effective S/D area with the channel region. CONCLUSIONS AND FUTURE ASPECTS The effect of Fin width thickness variation is increasing as the feature size of the FinFET device reduces. This work realized that the linear variation in the overall Fin width thickness introduces comparable variations in electrical performance parameters for FinFET device. For instance, there is a significant improvement in DIBL for Fin thickness variation from -70 to +70 because these variations are directly correlated to the Fin thickness reduction. These insights will allow technologists and designers to capture a valid performance characteristic for Fin width variations effects to meet future design challenges in the nanometer regime. REFERENCES [1] A Khakifirooz, IEEE Trans. Elect. Dev., vol. 55(6), pp. 1401-1408, 2008. [2] RS Rathore, IEEE 4th International Conference on Signal Processing, Computing and Control (ISPCC), Solan, 2017, pp. 377-380. [3] RS Rathore, Superlattices and Microstructures, vol. 113, pp. 213-227, 2018. [4] X Wu, IEEE Trans. Elect. Dev., vol. 52(1), pp. 63-68,2005. [5] AR Brown, IEEE Trans. Elect. Dev., vol. 54(11), pp. 3056-3063, 2007. Figure 1
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Pandey, Shubham, A. K. Sachan, Anupam Rawat, and Saurabh Singh. "Optimum Pavement Thickness for Rigid Pavement in UP Eastern Region." International Journal of Engineering and Advanced Technology 10, no. 5 (June 30, 2021): 173–81. http://dx.doi.org/10.35940/ijeat.e2738.0610521.
Abstract:
Highways are important in the growth of the economy of the nation. Pavement distributes and reduces the loads to the subgrade so as not to destruct the pavement foundation and subgrade. Thermal stresses are more vulnerable and to be included as the ability to contract and expand concrete is very less. The roads provide vehicle access to various points in all weather conditions and provide road users with a clean, smooth, and comfortable ride without unnecessary delay or excessive wear and tear. Since the UP eastern region faces tremendous temperature differences, load variations, and moisture conditions. This paper puts an attempt to identify the optimum thickness of the rigid pavement to sustain these extreme temperature variations, high humidity, and various load configurations. In this paper the various configurations of the loads are taken from the IRC 6: 2016 along with the various moisture and temperature data are taken from the Indian Meteorological Department (IMD) ministry of Earth and Science government of India. The paper gives a brief idea of pavement thickness selection. This paper utilizes Finite Element Method (FEM) based Software’s KENPAVE along with ANSYS 12.1 for a better understanding of the critical stress and its positions where the pavement needs attention in the design. All these varying conditions are incorporated in these software’s and the results obtained were in the form of figures, graphs, and deflected shapes. Parametric variation in the pavement section (i.e. variation in thickness of PQC, DLC layer, and in Modulus of Elasticity), variation in poisons ratio and temperature by using these results and doing cost analysis the optimum pavement thickness was obtained.
17
Riyadi, Tri Widodo Besar, and Sopyan Sahid Fatuloh. "The effect of internal pressure and thickness on the creep strain of the superheater pipes." Applied Research and Smart Technology (ARSTech) 1, no. 1 (June 5, 2020): 11–15. http://dx.doi.org/10.23917/arstech.v1i1.21.
Abstract:
Superheater pipes in turbines commonly are used to produce superheated steam. Internal pressure is critical for steam superheater elements. The pipes in such applications are vulnerable to temperature environments, which can bring the component to enter the creep regime, creep deformation, or even creep fracture. In general, most of the failures in boilers are caused by creep. Creep-resistant materials used in facilities operated at high temperatures must, therefore, be able to withstand the highest possible temperature loads. This study aims to investigate the creep behaviour of a 617 alloys steel steam pipe, which operated within 100,000 hours. The temperature of steam was set at 700?C, and the pressure in the pipe was 35 MPa. Abaqus software based on the finite element method was used in the study. The effect of internal pressure and pipe thickness on the creep strains was observed. The variation of the internal pressure was 35, 37.5, 40, 42.5, and 45 MPa. Whereas, the thickness variations were 30, 35, 40, 45, and 50 mm. The simulation results revealed that an increase in the internal pressure and the decrease of the pipe thickness increase the creep strain. This study can be used to predict the possibility of creep damaged for the superheater pipes operated at high temperatures, which have different thicknesses.
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Xu, Weisheng, and Jin Zhang. "Investigation of Through-Thickness Residual Stress, Microstructure and Texture in Radial Forged High-Strength Alloy Steel Tubes." Metals 12, no. 4 (April 4, 2022): 622. http://dx.doi.org/10.3390/met12040622.
Abstract:
Gradient variations of through-thickness residual stress, microstructure and texture greatly affect the performance of cold radial forged tubes. In this work, the through-thickness distribution of residual stress was measured based on the Debye ring. The microstructure was characterized with the electron backscattering diffraction technique. The texture was measured by the X-ray diffractometer. The influence of microstructure and texture on the strength and anisotropy of forged tubes with different thickness reductions was analyzed. The results show that the residual stress varies gradually from compressive to tensile from the outer to inner surface. The microhardness of the outer surface is lower than the inner. The dislocation density and low-angle grain boundary fraction are the smallest in the one-third thickness. The dislocation density and low-angle grain boundary fraction increase gradually from the one-third thickness to the inner surface. The main texture components of the forged tube include {111}<110>, {001}<110> and {114}<110>. Texture {111}<110> deflects gradually toward {114}<110>, {112}<110> and {110}<110> from the external tube to the internal tube. The gradient variation of strength mainly resulted from the difference of the dislocation density. The difference of strength along the radial direction is reduced with a larger thickness reduction. This work has important significance for improving the performance of high-strength alloy steel tubes processed by cold radial forging.
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Wicaksono, Ariawan Bayu, Zulkifli Djafar, and Asniawaty Kusno. "Sound Absorption Coefficient Analysis for Composite Made of Agricultural Waste." Materials Science Forum 1091 (June 5, 2023): 161–70. http://dx.doi.org/10.4028/p-mo2395.
Abstract:
The background of this study is to reduce and reuse agricultural waste, specifically rice husk and rice straw waste. This research aimed to determine the sound absorption coefficient / noise absorption coefficient (NAC) of a composite material made of rice husk and rice straw so that it can be used as an alternative acoustic material. Rice husk and straw were processed into composite materials using a polyester matrix with a volume fraction of 30:70 and sample thickness variations of 25 mm and 40 mm. In addition to treating variations in sample thickness, samples were made with different cavity holes diameter variations, including flat (without cavity holes), 3 mm, and 4 mm with 10 mm cavity depth. Samples were tested using a type 4206 impedance tube with two microphones according to the ASTM E1050 standard in the 200 – 1600 Hz frequency range. According to the findings of this study, the maximum sound absorption coefficient value of the rice straw composite material is obtained from samples with a thickness variation of 40 mm and a cavity diameter of 3 mm, with α value of 0.87 at a high frequency of 1,600 Hz. Meanwhile, the rice husk composite material's maximum sound absorption coefficient value was obtained from samples with a thickness variation of 40 mm and a cavity diameter of 3 mm with α value of 0.65 at a low frequency of 400 Hz. According to the findings of this study, rice straw composite material and rice husk composite material have different properties as sound absorbing materials and can be used as acoustic materials in a specific frequency range.
20
Yoon, Jun-Sik. "DC Performance Variations of SOI FinFETs with Different Silicide Thickness." Advances in Condensed Matter Physics 2018 (2018): 1–7. http://dx.doi.org/10.1155/2018/2426863.
Abstract:
DC performance and the variability of n-type silicon-on-insulator dopant-segregated FinFETs with different silicide thickness (Tsili) are analyzed. DC parameters including threshold voltage, low-field-mobility-related coefficient, and parasitic resistance are extracted from Y-function method for the comparison of DC performance and variability, and the correlation analysis. All the devices show similar subthreshold characteristics, but the devices with thicker Tsili have greater threshold voltages. The devices with thicker Tsili suffer from the DC performance degradation and its greater variations because the Schottky barrier height at the NiSi/Si interface increases and fluctuates greatly. This effect is validated by greater threshold voltages, larger parasitic resistances, and high correlations among all the DC parameters for the thicker Tsili. The devices with thicker Tsili also have higher low-frequency noise because of larger parasitic resistances and their correlated mobility degradations. Therefore, the device with relatively thin Tsili is expected to have better DC performance and variability concerns.
21
Hui Zhang, Yu-ran Wang, Shu-yi Zhang, and Li Fan. "Nondestructive evaluation of thickness variations for elastic plates by high-overtone bulk acoustic resonance." IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control 59, no. 12 (December 2012): 2709–15. http://dx.doi.org/10.1109/tuffc.2012.2512.
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COSCAS, G. "Choroidal thickness measurements and variations with age, gender in normal, myopia and high myopia." Acta Ophthalmologica 91 (August 2013): 0. http://dx.doi.org/10.1111/j.1755-3768.2013.3211.x.
23
Gee, Jeff, and Dennis V. Kent. "Variations in layer 2A thickness and the origin of the central anomaly magnetic high." Geophysical Research Letters 21, no. 4 (February 15, 1994): 297–300. http://dx.doi.org/10.1029/93gl03422.
24
Long, Hui, I. S. Al-Tubi, and M. T. M. Martinze. "Analytical and Experimental Study of Gear Surface Micropitting Due to Variable Loading." Applied Mechanics and Materials 750 (April 2015): 96–103. http://dx.doi.org/10.4028/www.scientific.net/amm.750.96.
Abstract:
This paper presents an investigation of the effect of load variation on gear tooth surface micropitting, for an application in planet gears in a wind turbine gearbox. To study the effect of load variation, two methods are employed: an experimental testing of gear micropitting under variable loading and a probabilistic analysis of gear contact stress and specific lubricant film thickness variations using the ISO Technical Report ISO/TR 15144-1:2010. The load variation of wind turbine gearbox is derived from SCADA (Supervisory Control and Data Acquisition) data recorded in operation. Both experimental and analytical results show that high levels of contact stress, load variations and repeated load cycles are determinant factors for the initiation and propagation of micropitting of gear tooth surfaces.
25
McMurray, Robert J., Alan G. Leacock, and Desmond Brown. "The Influence of Through-Thickness Material Property Variation on Stretch Forming Springback." Key Engineering Materials 473 (March 2011): 436–43. http://dx.doi.org/10.4028/www.scientific.net/kem.473.436.
Abstract:
Stretch forming is commonly used in the manufacture of low-volume convex aircraft panels. The gentle curvature and high degree of stretch leads to relatively low levels of elastic recovery post forming. Previous investigations [1] have shown that there is a large difference in the measured springback depending upon which side of an Alclad aluminium sheet is in contact with the tool surface. Initial investigation into the clad layer properties revealed no accountable variation in either thickness or strength. Instead the asymmetric springback behaviour was attributed to material property variations through the alloy core of the sheet. An analytical method for the prediction of the asymmetric springback incorporating the through thickness property variation is presented. Material strengths at specific through thickness positions were determined using a procedure based on residual strength measurements. The predicted results correlate well with the experimental data, which had initially demonstrated the asymmetric springback
26
Steeples, D. W., R. D. Miller, and R. A. Black. "Static corrections from shallow‐reflection surveys." GEOPHYSICS 55, no. 6 (June 1990): 769–75. http://dx.doi.org/10.1190/1.1442889.
Abstract:
Shallow seismic reflection surveys can assist in determination of velocity and/or thickness variations in near‐surface layers. Static corrections to seismic reflection data compensate for velocity and thickness variations within the “weathered zone.” An uncompensated weathered‐layer thickness variation on the order of 1 m across the length of a geophone array can distort the spectrum of the signal and result in aberrations on final stacked data. P-wave velocities in areas where the weathered zone is composed of unconsolidated materials can be substantially less than the velocity of sound in air. Weathered‐layer thickness variation of 1 m in these low‐velocity materials could result in a static anomaly in excess of 3 ms. Shallow‐reflection data from the Texas panhandle illustrate a real geologic situation with sufficient variability in the near surface to significantly affect seismic signal reflected from depths commonly targeted by conventional reflection surveys. Synthetic data approximating a conventional reflection survey combined with a weathered‐layer model generated from shallow‐reflection data show the possible dramatic static effects of alluvium. Shallow high‐resolution reflection surveys can be used both to determine the severity of intra‐array statics and to assist in the design of a filter to remove much of the distortion such statics cause on deeper reflection data. The static effects of unconsolidated materials can be even more dramatic on S-wave reflection surveys than on comparable P-wave surveys.
27
Suryani, E., M. M. Pratamaningsih, R. Q. Muslim, Erwinda, D. P. Hati, P. Kricella, E. S. Nugroho, R. E. Subandiono, and M. Anda. "Variations in peat soil properties at the west coast of Sumatra Island." IOP Conference Series: Earth and Environmental Science 1025, no. 1 (May 1, 2022): 012025. http://dx.doi.org/10.1088/1755-1315/1025/1/012025.
Abstract:
Abstract Peat in coastal areas has different characteristics compared to peat in inland areas because coastal peat usually has high DHL, pyrite, marine sandy substratum, and maturity which is generally classified as hemic to sapric. These variants in soil characteristics drive peculiarity in its management. For this reason, a more detailed information about the characteristics is needed to allow sustainable management and utilization. A total of 78 peat soil samples from 20 peat soil profiles taken over west coast of Sumatra was studied and analyzed for their physical and chemical properties. Field observations were made using a peat auger to determine thickness and maturity, substratum, presence of pyrite, and others. Results showed that peat thickness varied from shallow (50-100 cm), medium (100-200 cm), to very deep (>700 cm); peat situated closer to the coast generally has shallow peat depth. Peat soil in coastal areas contained a mineral soil substrate with a sand content of >70%. It was found that soil had a hemic maturity level and a very acidic to acidic pH value (pH 2.5-5.4). The P2O5 content extracted by 25% HCl varied from low to moderate, while K2O content of 25% HCl extraction was very low. Cations K, Na, and Ca were very low to very high, while Mg spanned from very low to high. Based on its thickness, 25% of peatland were not suitable (Nrc) for general agriculture uses because of >300 cm thickness. Therefore, it is necessary to improve soil fertility and water management in several places.
28
Nöhring, Wolfram G., Jan Grießer, Patrick Dondl, and Lars Pastewka. "Surface lattice Green’s functions for high-entropy alloys." Modelling and Simulation in Materials Science and Engineering 30, no. 1 (December 17, 2021): 015007. http://dx.doi.org/10.1088/1361-651x/ac3ca2.
Abstract:
Abstract We study the surface elastic response of pure Ni, the random alloy FeNiCr and an average FeNiCr alloy in terms of the surface lattice Green’s function. We propose a scheme for computing per-site Green’s function and study their per-site variations. The average FeNiCr alloys accurately reproduces the mean Green’s function of the full random alloy. Variation around this mean is largest near the edge of the surface Brillouin-zone and decays as q −2 with wavevector q towards the Γ-point. We also present expressions for the continuum surface Green’s function of anisotropic solids of finite and infinite thickness and show that the atomistic Green’s function approaches continuum near the Γ-point. Our results are a first step towards efficient contact calculations and Peierls–Nabarro type models for dislocations in high-entropy alloys.
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Kim, Yeon-Bok, and Jeong Kim. "Influence of Specimen Thickness on the Acquisition of Al6061-T6 Material Properties Using SHPB and Verified by FEM." Materials 14, no. 1 (January 4, 2021): 205. http://dx.doi.org/10.3390/ma14010205.
Abstract:
The Split-Hopkinson pressure bar (SHPB), which is used for acquiring material properties at high strain rates (102–104 s−1), requires proper specimen size selection. Under the same applied pressure, an increased S-S curve is obtained as the thickness of the specimen decreases. In this study, 1.5 t, 2.0 t, 3.0 t, 5.0 t, and 7.0 t specimens of Al6061-T6 material were tested under 1.0 bar to understand the influence of specimen thickness on the acquisition of material properties. To grasp the behavior of the SHPB test in real time, Finite Element Method (FEM) was performed using the LS-DYNA program. During the SHPB test, the impedance is increased due to the variation in the specimen area. Because of the influence of impedance, the transmitted pulse increases, and the reflected pulse decreases. As a result, the specimen is deformed in the high-strain rate region, and the S-S curve is increased as the thickness decreases. In addition, by performing the test under different pressure conditions that created similar strain rate regions, the material properties remained constant with thickness variations.
30
Schwartz, Kenneth B., Jinlong Cheng, Vijay N. Reddy, Matilda Fone, and Howard P. Fisher. "Crystallinity and Unit Cell Variations in Linear High-Density Polyethylene." Advances in X-ray Analysis 38 (1994): 495–502. http://dx.doi.org/10.1154/s0376030800018152.
Abstract:
Abstract The degree of crystallinity and unit cell parameters have been determined using WAXS on a number of compression molded high-density polyethylene (HDPE) plaques processed at widely varying conditions of crystallization and annealing times and temperatures. Changes in unit cell parameters with variations in processing conditions can be explained in terms of increases in lamellar thickness of polyethylene crystals with increasing thermal treatments. Concomitant increases in the degree of crystallinity of these samples can also be explained in terms of lamellar thickening and other changes in polyethylene morphology. Crystallinity determinations using XRD data are also compared with values determined by differential scanning calorimetry (DSC) and solid-state 13C nuclear magnetic resonance (NMR). Comparisons of crystallinity values obtained by these three different techniques can reveal details of the morphology of HDPE including the presence of an interfacial zone in addition to the crystalline and amorphous components of the system.
31
Fang, Jun, Shi Qiang Lu, Chuang Liang, and Xu Guang Min. "Springback Behavior of High Strength Titanium Tube after Bending under Variations of Material Property Parameters." Key Engineering Materials 881 (April 2021): 13–18. http://dx.doi.org/10.4028/www.scientific.net/kem.881.13.
Abstract:
In order to reveal the springback behavior of high strength TA18 tube after numerical control (NC) bending under the variations of material property parameters, the finite element (FE) model of the whole process for the high strength TA18 tube during NC bending was established under ABAQUS code and its stability was evaluated. Then, using the model, the springback behavior after tube bending under the variations of material property parameters was studied, and the significance of material property parameters on springback was revealed. The results show that the springback angle decreases with the increase of the Young’s modulus, hardening exponent and thickness anisotropy exponent or with the decrease of the strength coefficient and yield stress. The significance of material property parameters on springback of the high strength TA18 tube after NC bending from high to low are the yield stress, Young’s modulus, strength coefficient, thickness anisotropy exponent and hardening exponent.
32
Ghosh, Sayantan, John N. Hooker, Caleb P. Bontempi, and Roger M. Slatt. "High-resolution stratigraphic characterization of natural fracture attributes in the Woodford Shale, Arbuckle Wilderness and US-77D Outcrops, Murray County, Oklahoma." Interpretation 6, no. 1 (February 1, 2018): SC29—SC41. http://dx.doi.org/10.1190/int-2017-0056.1.
Abstract:
Natural fracture aperture-size, spacing, and stratigraphic variation in fracture density are factors determining the fluid-flow capacity of low-permeability formations. In this study, several facies were identified in a Woodford Shale complete section. The section was divided into four broad stratigraphic zones based on interbedding of similar facies. Average thicknesses and percentages of brittle and ductile beds in each stratigraphic foot were recorded. Also, five fracture sets were identified. These sets were split into two groups based on their trace exposures. Fracture linear intensity (number of fractures normalized to the scanline length [[Formula: see text]]) values were quantified for brittle and ductile beds. Individual fracture intensity-bed thickness linear equations were derived. These equations, along with the average bed thickness and percentage of brittle and ductile lithologies in each stratigraphic foot, were used to construct a fracture areal density (number of fracture traces normalized to the trace exposure area [[Formula: see text]]) profile. Finally, the fracture opening-displacement size variations, clustering tendencies, and fracture saturation were quantified. Fracture intensity-bed thickness equations predict approximately 1.5–3 times more fractures in the brittle beds compared with ductile beds at any given bed thickness. Parts of zone 2 and almost entire zone 3, located in the upper and middle Woodford, respectively, have high fracture densities and are situated within relatively organic-rich (high-GR) intervals. These intervals may be suitable horizontal well landing targets. All observed fracture cement exhibit a lack of crack-seal texture. Characteristic aperture-size distributions exist, with most apertures in the 0.05–1 mm (0.00016–0.0032 ft) range. In the chert beds, fracture cement is primarily bitumen or silica or both. Fractures in dolomite beds primarily have calcite cement. The average fracture spacing indices (i.e., bed thickness-fracture spacing ratio) in brittle and ductile beds were determined to be 2 and 1.2, respectively. Uniform fracture spacing was observed along all scanlines in the studied beds.
33
Budiana, Budiana, Choklin Brema Situmorang, Hana Mutialif Maulidiah, and Widya Rika Puspita. "Effect of Current, Voltage, Temperature, and Time Variations on Thickness of Steel using Electroplating Process." JURNAL INTEGRASI 15, no. 2 (October 31, 2023): 97–103. http://dx.doi.org/10.30871/ji.v15i2.6519.
Abstract:
The use of low carbon steel is categorized as one of the supporting materials in industrial and technological developments because it has high ductility and toughness. However, low carbon steel has limitations in terms of corrosion resistance. There are several ways to increase corrosion resistance in steel. One of them is by providing a layer of protection on the steel surface. The steel plating method used is the electrolysis method or electroplating method. This study aims to determine the influence of variations in current, voltage, temperature, and time on the thickness of the coating formed on steel. The steel plating process is carried out by electroplating process where the coating material or anode is Nickel (Ni) with dimensions (60 mm x 30 mm x 0,1 mm). In comparison, the coated object or cathode is SK5 steel with dimensions (50 mm x 20 mm x 0,3 mm). The aim of this study is to investigate the effect of Current, Voltage, Temperature, and Time Variations on the thickness of steel using electroplating processes. Moreover, all factors will be optimised to achieve the best thickness for steel. Consequently, the corrosion resistance of SK5 can be significantly improved by increasing its thickness. The current variations were used 1A, 2A, 3A, and 4A; voltage variations were used 3V, 6V, 9V, and 12V; temperature variations were used 30°C, 40°C, and 50°C; and times variations were used 0 m, 5 m, 10 m, and 20 m. Based on the results of research that has been carried out on all samples, it is concluded that current, voltage, temperature and time affect the thickness of the sample in the electroplating process. The current, voltage, temperature and time values are linearly related to the thickness resulting from the electroplating process.
34
Blaschke, Daniel N., Cody Miller, Ryan Mier, Carl Osborn, Sean M. Thomas, Eric L. Tegtmeier, William P. Winter, John S. Carpenter, and Abigail Hunter. "Predicting electrical conductivity in Cu/Nb composites: A combined model-experiment study." Journal of Applied Physics 132, no. 4 (July 28, 2022): 045105. http://dx.doi.org/10.1063/5.0096880.
Abstract:
The generation of high magnetic fields requires materials with high electric conductivity and good strength properties. Cu/Nb composites are considered to be good candidates for this purpose. In this work, we aim to predict, from theory, the dependence of electric conductivity on the microstructure, most notably on the layer thickness and grain sizes. We also conducted experiments to calibrate and validate our simulations. Bimetal interfaces and grain boundaries are confirmed to have the largest impact on conductivity in this composite material. In this approach, a distribution of the layer thickness is accounted for in order to better model the experimentally observed microstructure. Because layer thicknesses below the mean free path of Cu significantly degrade the conductivity, an average layer thickness larger than expected may be needed to meet conductivity requirements in order to minimize these smaller layers in the distribution. We also investigate the effect of variations in volume fraction of Nb and temperature on the material’s conductivity.
35
Ravindra, N. M., J. Narayan, Dariush Fathy, J. K. Srivastava, and E. A. Irene. "Silicon oxidation and Si–SiO2 interface of thin oxides." Journal of Materials Research 2, no. 2 (April 1987): 216–21. http://dx.doi.org/10.1557/jmr.1987.0216.
Abstract:
High-resolution transmission electron microscopy (HRTEM) and ellipsometry techniques have been employed to measure thicknesses of silicon oxide, grown at 800°C in dry oxygen, in the thickness range of 2–20 nm. While the oxide growth data measured from TEM obey a nearly linear behavior, those obtained from ellipsometry are seen to vary nonlinearly. The interface structure as function of the increasing oxide thickness was studied using HRTEM. At these oxidation temperatures, the earlier reported variations of roughness at the interface on the oxide thickness for oxides grown at 900°C are not seen. Attempts aimed at correlating the high-resolution transmission electron micrographs with some physical parameters like the refractive index and the dielectric breakdown lead to considerations of the importance of the effect of protrusions of silicon atoms of 1 mm size into SiO2 layers on the interface properties. These findings lead to explanations of some key features concerning the refractive index and density of thin SiO2.
36
Kahn, Brian H., Annmarie Eldering, Michael Ghil, Simona Bordoni, and Shepard A. Clough. "Sensitivity Analysis of Cirrus Cloud Properties from High-Resolution Infrared Spectra. Part I: Methodology and Synthetic Cirrus." Journal of Climate 17, no. 24 (December 15, 2004): 4856–70. http://dx.doi.org/10.1175/jcli-3220.1.
Abstract:
Abstract A set of simulated high-resolution infrared (IR) emission spectra of synthetic cirrus clouds is used to perform a sensitivity analysis of top-of-atmosphere (TOA) radiance to cloud parameters. Principal component analysis (PCA) is applied to assess the variability of radiance across the spectrum with respect to microphysical and bulk cloud quantities. These quantities include particle shape, effective radius (reff), ice water path (IWP), cloud height Zcld and thickness ΔZcld, and vertical profiles of temperature T(z) and water vapor mixing ratio w(z). It is shown that IWP variations in simulated cloud cover dominate TOA radiance variability. Cloud height and thickness, as well as T(z) variations, also contribute to considerable TOA radiance variability. The empirical orthogonal functions (EOFs) of radiance variability show both similarities and differences in spectral shape and magnitude of variability when one physical quantity or another is being modified. In certain cases, it is possible to identify the EOF that represents variability with respect to one or more physical quantities. In other instances, similar EOFs result from different sets of physical quantities, emphasizing the need for multiple, independent data sources to retrieve cloud parameters. When analyzing a set of simulated spectra that include joint variations of IWP, reff, and w(z) across a realistic range of values, the first two EOFs capture approximately 92%–97% and 2%–6% of the total variance, respectively; they reflect the combined effect of IWP and reff. The third EOF accounts for only 1%–2% of the variance and resembles the EOF from analysis of spectra where only w(z) changes. Sensitivity with respect to particle size increases significantly for reff several tens of microns or less. For small-particle reff, the sensitivity with respect to the joint variation of IWP, reff, and w(z) is well approximated by the sum of the sensitivities with respect to variations in each of three quantities separately.
37
Kabius, B., V. Seybold, S. Hiller, A. Rilk, E. Zellmann, and W. Probst. "Energy-Filtering Techniques for Thick Samples." Microscopy and Microanalysis 6, S2 (August 2000): 166–67. http://dx.doi.org/10.1017/s1431927600033328.
Abstract:
Imaging of sample regions with a thickness significantly larger than the extinction length and strong thickness variations introduces two major problems for transmission electron microscopy (TEM) : (i) inelastic scattering increases the energy width of the transmitted electrons and therefore the resolution decreases (ii) the contrast differences caused by thickness variations can be higher than the dynamic range of the detector system.Both problems can be solved by using energy filtering techniques. The advantage here is that for energy filtered imaging the resolution limit is not determined by the sample thickness but by the width of the energy selection aperture. Fig. 1 shows three envelope functions of the temporal coherence calculated for different values of the energy width. The functions were plotted for an acceleration voltage of 200 kV and a high voltage stability of 2 ppm.
38
Jacobsson, H. "Disc brake judder considering instantaneous disc thickness and spatial friction variation." Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 217, no. 5 (May 1, 2003): 325–42. http://dx.doi.org/10.1243/095440703321645043.
Abstract:
Brake judder is a braking-induced vibration. The character of judder is typical of forced vibrations passing through a critical speed. No specific friction characteristic is needed for judder to occur. In two previous models, i.e. a rotor-stator model and a whole vehicle model, the vibration during a brake application was simulated. The vibrations were assumed to be driven by a brake torque variation (BTV) during a wheel revolution. The BTV was assumed to be proportional to the brake pressure variation (BPV) which was measured. Moreover, the proportionality constant was assumed to be independent of the braking conditions. Verifying measurements were made on a street going vehicle with strong disc thickness variation (DTV) on one of its front wheels. The measured vibration variation during braking was predicted almost exactly by the models. However, the maximum measured vibration level could only be approximated. In the present paper a more accurate analysis of the measurements was found to improve strongly the agreement between predicted and measured vibrations. Hence, the deviation in slope between measured and experimentally generated curves was markedly reduced by replacing the overall mean values of brake pressure level, etc. by slowly varying time functions. The new extended model of the present paper takes into account that the BTV may be generated by variations in normal force (i.e. BPV) and other synchronous variations (called BXV), e.g. spatial friction variation and variation of the equivalent brake radius. The result indicates that BXV may be induced by high BPV levels. Even at judder vibrations primarily caused by heavy DTV (20 μm or more in the cold state), there may be considerable contributions to the vibration level from other synchronous disturbances, i.e. BXV. Further, it was found that the pad stiffness increases with the brake pressure. For such a pad stiffness characteristic, an increase of the DTV level (for whatever reason) by 50 per cent might result in more than a 100 per cent increase in the corresponding BPV and BTV levels. Hence, a progressive pad is more sensitive to increases of the DTV level than a linear pad would be.
39
Mahmoud Ahmed, Naser, M. Roslan Hashim, and Hassan Zainuriah. "Effects of Layer Thickness and Incident Angle Variations on DBR Reflectivity." Materials Science Forum 517 (June 2006): 29–32. http://dx.doi.org/10.4028/www.scientific.net/msf.517.29.
Abstract:
In this paper we discussed the relation between depth errors that happened in films growth and incidence angle variation on DBR reflectivity. We assume that there is 10% depth error in high and low index materials, and there are four plus one situations to be considered. Four are combinations of Hi +/- 10% error and Lo +/- 10% error, and no error. Our simulation results show that the depth error makes the reflective band shift and it almost doesn’t reduce reflectivity. The thickness error of +/- 10% in (Al0.4Ga0.6N/GaN) DBR structure (15 pairs) at 420nm was 42nm. A theoretical analysis using Transfer Matrix Mode with MATLAB software on the influence of layer thickness and incidence angle variation in vertical-cavity surface-emitting lasers with distributed Bragg reflectors (DBRs) on lasing wavelength is presented. It is shown that changing the thickness of the layers in the DBR mirror by only 10% is sufficient to produce shifts in the peak reflectance wavelength up to ± 20 nm (for a blue laser at 420nm). This could limit the precision of a desired wavelength, which is its reproducibility.
40
Eşiyok, Dursun, Kadri Bozokalfa, and Tansel Kaygisiz-Aşçioğul. "Variability, heritability and association analysis in plant traits of swiss chard (Beta vulgaris subsp. cicla)." Genetika 43, no. 2 (2011): 239–52. http://dx.doi.org/10.2298/gensr1102239e.
Abstract:
Plant breeders mainly interested in improvement agronomic properties of desirable trait accompanied with genetic architecture of major characters and their interrelationship. Genetic variability and character association are prime importance and provide essential contribution for successful breeding programme. In the present research genetic variability, heritability, phenotypic and genotypic correlations of several agronomic characters were studied in fifty-four swiss chard accessions and cultivars. Analysis of variance observed highly significant variations among accessions, and phenotypic coefficient of variation (PCV) was higher magnitude of genotypic coefficient of variation (GCV) for all agronomic characters. The lamina length, lamina width, petiole thickness, petiole width, lightness, chroma and leaf dry matter observed high magnitude broad sense heritable characters accompanied with high genetic advance. Genotypic correlation coefficient showed higher than phenotypic correlation coefficient which could be explained by low environmental effect on investigated agronomic traits. Positive correlation was revealed between petiole length, lamina length, lamina width, petiole thickness and petiole width which comprise total yield in swiss chard.
41
Xiao, Kai, Haibo Yuan, J. Varela, Hu Zhan, Jifeng Liu, R. Abramo, J. Alcaniz, et al. "The mini-JPAS: A Study of the Wavelength Dependence of the Photon Response Nonuniformity of the JPAS-Pathfinder Camera." Astrophysical Journal Supplement Series 257, no. 2 (November 12, 2021): 31. http://dx.doi.org/10.3847/1538-4365/ac1d43.
Abstract:
Abstract Understanding the origins of small-scale flats of CCDs and their wavelength-dependent variations plays an important role in high-precision photometric, astrometric, and shape measurements of astronomical objects. Based on the unique flat data of 47 narrowband filters provided by JPAS-Pathfinder, we analyze the variations of small-scale flats as a function of wavelength. We find moderate variations (from about 1.0% at 390 nm to 0.3% at 890 nm) of small-scale flats among different filters, increasing toward shorter wavelengths. Small-scale flats of two filters close in central wavelengths are strongly correlated. We then use a simple physical model to reproduce the observed variations to a precision of about ±0.14% by considering the variations of charge collection efficiencies, effective areas, and thicknesses between CCD pixels. We find that the wavelength-dependent variations of the small-scale flats of the JPAS-Pathfinder camera originate from inhomogeneities of the quantum efficiency (particularly charge collection efficiency), as well as the effective area and thickness of CCD pixels. The former dominates the variations in short wavelengths, while the latter two dominate at longer wavelengths. The effects on proper flat-fielding, as well as on photometric/flux calibrations for photometric/slitless spectroscopic surveys, are discussed, particularly in blue filters/wavelengths. We also find that different model parameters are sensitive to flats of different wavelengths, depending on the relations between the electron absorption depth, photon absorption length, and CCD thickness. In order to model the wavelength-dependent variations of small-scale flats, a small number (around 10) of small-scale flats with well-selected wavelengths are sufficient to reconstruct small-scale flats in other wavelengths.
42
Lee, Tae Gon, Seung-Young Yu, and Hyung Woo Kwak. "VARIATIONS IN CHOROIDAL THICKNESS AFTER HIGH-DOSE SYSTEMIC CORTICOSTEROID TREATMENT IN CHILDREN WITH CHRONIC GLOMERULONEPHRITIS." Retina 35, no. 12 (December 2015): 2567–73. http://dx.doi.org/10.1097/iae.0000000000000626.
43
Costa, Danusa Silva da, Geovana Rocha Placido, Katiuchia Pereira Takeuchi, and Tainara Leal de Sousa. "Physical and biometric characterization of jabuticaba variety 'Pingo De Mel' oriunda of cerrado goiano." Research, Society and Development 9, no. 5 (April 1, 2020): e146953323. http://dx.doi.org/10.33448/rsd-v9i5.3323.
Abstract:
The biometric and physical characterization can provide information on format, yield, concentration of soluble solids. The objective was to characterize physically and biometrically the jabuticaba variety 'Pingo de mel' from the cerrado of Goiás. 200 jaboticaba were used. The content of total soluble solids, longitudinal and transverse diameters, total mass, volume, shape index, density, yield of peeled pulp and the thickness of the peeled pulp were determined. The total soluble solids 15,16 ° Brix, soluble solids content is one of the most important tools to estimate fruit quality. The longitudinal and transverse diameter was 22.25 and 21.56 mm, respectively. The total mass had an average variation because the coefficient of variation was above 20%. Variations can occur due to cultivation techniques and climate can be related to this also variations presented for the volume of this fruit. As for the format index, the fruit was classified as round. The density was 8.35 g mL -1, yield and pulp thickness were already high. Samples of total soluble solids and yield are parameters used as control and selection by the food industry, it means that the fruits in evaluation presented good potential of industrial processing.
44
Saravanos, Dimitris A., and Paul R. Heyliger. "Mechanics and Computational Models for Laminated Piezoelectric Beams, Plates, and Shells." Applied Mechanics Reviews 52, no. 10 (October 1, 1999): 305–20. http://dx.doi.org/10.1115/1.3098918.
Abstract:
A considerable number of laminate theories, analytical approaches, numerical solutions and computational models have been reported for the analysis of laminates and structures with piezoelectric actuators or sensors. This article provides a review of published work in this area of mechanics. The reported laminate theories and structural mechanics are classified based on fundamental assumptions, the approximation of the through-the-thickness variation of the electromechanical state variables, the method of representation of piezoelectric layers, and their capability to model curvilinear geometries and thermal effects. The performance, advantages and limitations of the various categories of laminate theories are subsequently assessed by correlating results obtained by representative average models. The capability of each theory to model global structural response, local through-the-thickness variations of electromechanical variables, stresses, and piezoelectric laminates of high thickness is also quantified. This review article includes 103 references.
45
Huang, Da-Ming, and Shyh-Hau Wang. "In Situ Monitoring and Assessment of Ischemic Skin Flap by High-Frequency Ultrasound and Quantitative Parameters." Sensors 24, no. 2 (January 7, 2024): 363. http://dx.doi.org/10.3390/s24020363.
Abstract:
Skin flap surgery is a critical procedure for treating severe skin injury in which post-surgery lesions must well monitored and cared for noninvasively. In the present study, attempts using high-frequency ultrasound imaging, quantitative parameters, and statistical analysis were made to extensively assess variations in the skin flap. Experiments were arranged by incising the dorsal skin of rats to create a skin flap using the chamber model. Measurements, including photographs, 30 MHz ultrasound B-mode images, skin thickness, echogenicity, Nakagami statistics, and histological analysis of post-surgery skin flap, were performed. Photograph results showed that color variations in different parts of the skin flap may readily correspond to ischemic states of local tissues. Compared to post-surgery skin flap on day 7, both integrated backscatter (IB) and Nakagami parameter (m) of the distal part of tissues were increased, and those of the skin thickness were decreased. Overall, relative skin thickness, IB, and m of the distal part of post-surgery skin flap varied from 100 to 67%, −66 to −61 dB, and 0.48 to 0.36, respectively. These results demonstrate that this modality and quantitative parameters can be feasibly applied for long-term and in situ assessment of skin flap tissues.
46
Wallin, Erin L. "Sensitivity of the high-frequency sounding method to variations in electrical properties." GEOPHYSICS 75, no. 4 (July 2010): WA189—WA197. http://dx.doi.org/10.1190/1.3464772.
Abstract:
Instrumentation for high-frequency sounding (HFS) was developed by the U.S. Geological Survey (USGS) in the late 1980s, continuing until 2006. To aid in this development, forward modeling and sensitivity analysis of vertical magnetic fields to electromagnetic (EM) properties between [Formula: see text] and [Formula: see text] were completed. Because these frequencies encompass the transition between the diffusion and propagation regimes, the HFS method ought to be sensitive to all properties contained in the EM wavenumber — namely, electrical conductivity, dielectric permittivity, and magnetic permeability as well as layer thickness. The models consist of three layers that simulate the contam-ination and remediation of dense nonaqueous-phase liquid (DNAPL) contaminants by oxidation. This scenario provides values of [Formula: see text] that would attenuate ground-penetrating radar signals and a range of [Formula: see text] which is a parameter that direct-current resistivity and low-frequency electromagnetic-induction (EMI) techniques are insensitive to. Conductivity and permittivity parameters are calculated with Archie’s law and the Bruggeman-Hanai-Sen (BHS) mixing formula. The importance of thickness and electrical properties to vertical-magnetic-field response of the models initially was addressed using numerical differencing between models containing slight perturbations in electrical properties. Results from this procedure were oscillatory and hence problematic, so analytic partial derivatives of the vertical magnetic field with respect to each parameter were computed for the same scenarios. The derivatives show that the sensitivity to the second-layer permittivity is less than the sensitivity to other properties, and the response is sensitive to slightly magnetic soils. It is also evident that sensitivity and resolution are limited by depth of penetration. The sensitivity curves and plots of the real and imaginary portions of the EM wavenumber demonstrate that propagation begins near [Formula: see text].
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Li, Zhuoyue, Cheng Wang, Xiangyu Ding, Xin Li, Jiabo Yu, Qiuliang Li, and Yi Qu. "Effect of Slurry Thickness on the Quality of Aluminized Coatings." Materials 15, no. 19 (September 29, 2022): 6758. http://dx.doi.org/10.3390/ma15196758.
Abstract:
Diffusion aluminum coating is crucial to protect aero-engine turbine blades from high-temperature oxidation. Slurry aluminizing, as a commonly-used coating preparation technology, has variations in the process parameters that directly affect the quality of the coating. Therefore, this paper investigates the effect of slurry thickness on coating quality. Different forms of aluminized coatings were obtained by coating nine DZ22B nickel-based superalloy plates of the same size with different slurry thicknesses while keeping other parameters constant. These aluminized coatings were characterized using a scanning electron microscope (SEM) with an energy dispersive spectrometer (EDS), an X-ray diffractometer (XRD), and a surface gauge. The results show that the AlNi phase dominates the matrix of the aluminized coating, and the outer layer of the coating has white dotted precipitates of Cr. As the slurry thickness increases, the coating thickness increases, and the proportion of the outer layer in the overall coating increases. In contrast, the thickness of the interdiffusion layer does not change significantly. The thicker the slurry, the higher the Al content of the coating surface. A medium-thickness slurry can form a smooth aluminizing coating with a roughness Ra < 4.5 μm surface. The combined results show that a medium-thick slurry can produce a high-quality coating.
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Röhlig, Martin, Ruby Kala Prakasam, Jörg Stüwe, Christoph Schmidt, Oliver Stachs, and Heidrun Schumann. "Enhanced Grid-Based Visual Analysis of Retinal Layer Thickness with Optical Coherence Tomography." Information 10, no. 9 (August 23, 2019): 266. http://dx.doi.org/10.3390/info10090266.
Abstract:
Optical coherence tomography enables high-resolution 3D imaging of retinal layers in the human eye. The thickness of the layers is commonly assessed to understand a variety of retinal and systemic disorders. Yet, the thickness data are complex and currently need to be considerably reduced prior to further processing and analysis. This leads to a loss of information on localized variations in thickness, which is important for early detection of certain retinal diseases. We propose an enhanced grid-based reduction and exploration of retinal thickness data. Alternative grids are computed, their representation quality is rated, and best fitting grids for given thickness data are suggested. Selected grids are then visualized, adapted, and compared at different levels of granularity. A visual analysis tool bundles all computational, visual, and interactive means in a flexible user interface. We demonstrate the utility of our tool in a complementary analysis procedure, which eases the evaluation of ophthalmic study data. Ophthalmologists successfully applied our solution to study localized variations in thickness of retinal layers in patients with diabetes mellitus.
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Sumakeris, Joseph J., Jason Henning, Michael J. O'Loughlin, Saptharishi Sriram, and Vijay Balakrishna. "Extremely Uniform, High Quality SiC Epitaxy on 100-mm Substrates." Materials Science Forum 600-603 (September 2008): 99–102. http://dx.doi.org/10.4028/www.scientific.net/msf.600-603.99.
Abstract:
We have developed a horizontal hot-wall reactor for growing extremely uniform epilayers on 100-mm diameter SiC substrates using a novel supplemental reagent source. Doping and thickness variations of 2% and 1% s / mean, respectively, have been demonstrated. The typical defect density is 2 cm-2. We describe the growth cell in detail and discuss the development of the design and process to produce these very uniform epilayers.
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Mozumder, SN, N. Nath, N. Akter, S. Akter, and BR Banik. "Variability and character association in cinnamon germplasm." Bangladesh Journal of Agricultural Research 41, no. 3 (September 24, 2016): 555–64. http://dx.doi.org/10.3329/bjar.v41i3.29726.
Abstract:
The experiment was conducted at the Regional Spices Research Center, BARI during May 2014 to April 2015 to study the variability and character association in cinnamon germplasm taking the characters - tree growth, leaf characteristics, bark thickness, specific bark weight and quality of bark of cinnamon plants. Range, variance and coefficient of variation of 30 different characters showed variations in 53 cinnamon accessions. High coefficient of variation was found for base girth, main stem height, number of tertiary branches/plant, tree volume, fresh and dry bark weight of tertiary branches. Bark thickness and specific bark weight gradually declined from main stem to lateral branches. The hierarchical cluster analysis with single scaled dendrogram showed eight clusters due to variation among the germplasm. Cluster III contained maximum 14 genotypes followed by cluster I and cluster VII, each having 12 genotypes. Association analysis revealed that significant correlation of base girth with tree volume, and secondary branches/plant had also significant correlation with leaf thickness and tree volume. It also revealed that significant correlation of fresh bark thickness of main stem with fresh bark thickness of primary, secondary and tertiary stems, also with fresh and dry bark weight of main, primary, secondary and tertiary stems. Specific bark weight had also significant correlation with fresh and dry bark weight of main, primary, secondary and tertiary barks.Bangladesh J. Agril. Res. 41(3): 555-564, September 2016