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D. Lepadatu R. Hambli A. Kobi A. Barreau 《The International Journal of Advanced Manufacturing Technology》2006,28(3-4):272-278
The aim of this paper is the statistical process control analysis of the tool wear evolution during metal extrusion process
for better understanding the principal causes that generate the variability of such a complex phenomenon. The wear prediction
is carried out using finite element simulation including the Archard wear model. The tool wear modeling is presented briefly
as well as the response surface methodology. The study is based on the application of the central composites designs and allows
for the analysis of the response (wear) sensitivity of the tool. The statistical investigation of the process makes it possible
to study the influence of each process parameter on the response sensitivity. 相似文献
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Baruch B. Schwarz Naomi Prusak Osama Swidan Adva Livny Kobi Gal Avi Segal 《International Journal of Computer-Supported Collaborative Learning》2018,13(2):189-211
This paper is about orchestrating the emergence of conceptual learning in a collaborative setting. We elaborate on the idea of critical moments in group learning, events which may lead to a particular development at the epistemic level regarding the shared object. We conjecture that teachers’ identification of critical moments may help them guide students to the emergence of conceptual learning. The complexity of small group settings in classrooms prevents teachers from noticing these critical moments, though. Here we present an environment, SAGLET (System for Advancing Group Learning in Educational Technologies), based on the VMT (Virtual Math Teams) environment (Stahl 2009), which allows teachers to observe multiple groups engaging in problem-solving in geometry. SAGLET capitalizes on machine learning techniques to inform teachers about on-line critical moments by sending them alerts, so that they can then decide whether (and how) to use the alerts in guiding their students. One teacher in an elementary school used SAGLET to help multiple groups of students solve difficult problems in geometry. We observed how the teacher mediated two cohorts of multiple groups at two different times in a mathematics classroom. We show that in both cases the teacher could detect the needs of the groups (partly thanks to the alerts) and could provide adaptive guidance for all the groups. 相似文献
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Highly fractionated designs are often used for screening purposes in order to reduce the number of runs. In fractionary-designed experiments, the factor effects are confounded with interactions that are potentially active. Estimating separately the confounded effects is sometimes difficult and the results may be inconclusive as to which effect is real. Foldover designs are usually used to resolve such ambiguities. In this article, a method based on overlapping designs that enables one to separate the confounded effects in a smaller amount of runs is proposed. We illustrate this with an application. 相似文献
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Samayendra Kumar Abhilash Chakraborty Sushobhan Kobi P. Gopalan T. R. S. Prasanna 《Journal of the American Ceramic Society》2022,105(5):3625-3635
In strontium- and magnesium-doped LaGaO3 (LSGM) electrolyte-based solid oxide fuel cells (SOFC), lanthanum-doped CeO2 (LDC) is usually used as buffer layer material to prevent reactions between LSGM electrolyte and NiO-based anode. In literature, based on results for one particular LSGM composition, a fixed buffer layer composition of 40% La-doped ceria (LDC40) has been used even with electrolytes of different LSGM compositions. In this study, we report the results of a comprehensive study of phase formations between various LSGM and LDC compositions. Our results show that only one LSGM/LDC combination results in no additional phases. For the other combinations, at least one and often two additional phases, LaSrGaO4 and LaSrGa3O7, result. Because LaSrGa3O7 has much lower conductivity, it is necessary to select combinations that avoid this phase. We propose that the combination that results in no additional phase should be considered favorably for SOFCs. For other LSGM compositions, LDC50 should be used as a buffer layer instead of LDC40 as is presently done in SOFC studies. Alternately, if LDC40 is preferred for buffer layer, then lower Sr content LSGM compositions should be used as electrolytes. These combinations are likely to lead to better long-term SOFC performance. 相似文献
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A single center,open‐label,randomized, parallel group study assessing the relationship between asymptomatic bacteriuria and inflammation in maintenance hemodialysis patients 下载免费PDF全文
Ilia Beberashvili Evgeni Golovko Liat Golinsky Nedal Garra Inna Sinuani Leonid Feldman Oleg Gorelik Shai Efrati Kobi Stav 《Hemodialysis international. International Symposium on Home Hemodialysis》2018,22(1):110-118
Introduction: The significance of asymptomatic bacteriuria in maintenance hemodialysis (MHD) patients remains controversial. We hypothesized that the presence of asymptomatic bacteriuria as a sole clinical manifestation of urinary tract infection (UTI) in asymptomatic MHD patient may contribute to the chronic inflammatory response. Our aim was to explore the relationship between asymptomatic bacteriuria and elevated levels of inflammatory markers in MHD patients. Methods: A randomized open‐label single center study of 114 MHD patients was conducted. Forty‐six patients presented negative urine culture and 41 subjects were excluded due to different reasons. The remaining 27 patients (mean age of 71.5 ± 12.2 years, 63% men), fulfilling the criteria for having asymptomatic bacteriuria, were randomly assigned to either the treatment group (13 patients) or the observational group (14 subjects). The treatment group received 7 days of antibiotic treatment given according to bacteriogram sensitivity. After 3 months of follow‐up all measurements of the study were repeated. The primary end point was change in inflammatory biomarkers from baseline by the end of the study. Findings: There were no statistically significant differences in white blood cell changes (P = 0.27), ferritin (P = 0.09), C‐reactive protein (P = 0.90), and interleukin‐6 (P = 0.14) levels between the groups from baseline to the end of study or at the end of the study. Analyzing cross‐sectional data, asymptomatic bacteriuria was found to not be a predictor of higher levels of inflammatory parameters at baseline. Discussion: Asymptomatic bacteriuria is not a modifiable risk factor for chronic inflammation in the MHD population. 相似文献
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Among the Li-ion conducting inorganic materials, lithium lanthanum zirconate (LLZO) is believed to possess good chemical stability against Li metal and hence considered to be a promising solid electrolyte for Li-ion batteries. However, systematic sets of studies conducted here at regular intervals during storage of Al-doped LLZO (cubic garnet) sintered pellets in ambient atmosphere have raised serious concerns over their structural/mechanical stability/integrity upon exposure to air. Spontaneous cracking/disintegration/pulverization of LLZO pellets takes place after about three weeks of exposure, primarily due to formation of La2Zr2O7 in the LLZO bulk; as found to be thermodynamically feasible at room temperature upon reaction with CO2/moisture. Steep increase in La2Zr2O7 content coincides with the spontaneous cracking/disintegration. Estimation suggests that internal stresses associated with the formation of La2Zr2O7 from LLZO can be high enough to cause spontaneous fracture. This mandates the development/fabrication/usage of solid-state cells using LLZO under stringent controls against exposure to atmospheric species. 相似文献
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Atmospheric modulation transfer function in the infrared 总被引:2,自引:0,他引:2
Buskila K Towito S Shmuel E Levi R Kopeika N Krapels K Driggers RG Vollmerhausen RH Halford CE 《Applied optics》2004,43(2):471-482
In high-resolution ultranarrow field-of-view thermal imagers, image quality over relatively long path lengths is typically limited by atmospheric degradation, especially atmospheric blur. We report our results and analyses of infrared images from two sites, Fort A. P. Hill and Aberdeen Proving Ground. The images are influenced by the various atmospheric phenomena: scattering, absorption, and turbulence. A series of experiments with high-resolution equipment in both the 3-5- and 8-13-microm regions at the two locations indicate that, as in the visible, image quality is limited much more by atmosphere than by the instrumentation for ranges even of the order of only a few kilometers. For paths close to the ground, turbulence is more dominant, whereas for paths involving higher average elevation, aerosol modulation transfer function (MTF) is dominant. As wavelength increases, turbulence MTF also increases, thus permitting aerosol MTF to become more dominant. A critical role in aerosol MTF in the thermal infrared is attributed to absorption, which noticeably decreases atmospheric transmission much more than in the visible, thereby reducing high-spatial-frequency aerosol MTF. These measurements indicate that atmospheric MTF should be a basic component in imaging system design and analysis even in the infrared, especially as higher-resolution hardware becomes available. 相似文献
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Bicycle injuries: a matter of mechanism and age 总被引:1,自引:0,他引:1
Siman-Tov M Jaffe DH;Israel Trauma Group Peleg K 《Accident; analysis and prevention》2012,44(1):135-139
Bicycle riding is a popular form of recreation with positive health and environmental effects. These road users are vulnerable to serious injuries, especially when motor vehicles are involved. The goal of this study was to characterize cyclist-related injuries according to motor vehicle involvement for adults versus children. A retrospective study was carried out using data from 11 trauma centers in the Israeli National Trauma Registry (2001-2007). Injuries were classified according to whether a motor vehicle was involved, and differences in injury characteristics were assessed for adults (18+ years) versus children (1-17 years). A total of 5529 patients were hospitalized for bicycle injuries, of whom 1765 were adults and 3764 were children. Thirty percent (n=1662) of all bicycle injuries involved motor vehicles, although the rate of injuries resulting in hospitalization was 37% among adults and 27% among children. Injury characteristics and hospital resource utilization differed substantially by age group. Cyclists struck by a motor vehicle presented with more severe injuries requiring more hospital resources and resulting in poorer outcomes than those not involved with motor vehicles. The interaction effect between motor vehicle involvement and age was significant for torso injuries and need for medical imaging. We found that injury characteristics, hospital resource utilization and health-related outcomes for bicycle injuries are highly dependent on patient's age and mechanism of injury. Effect modification of motor vehicle involvement by age may in part reflect physicians' attitudes toward pediatric imaging. The risks identified in this study should be used for preparedness and management of trauma hospitalizations from bicycle injuries. 相似文献