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نتیجه جستجو - نقص

تعداد مقالات یافته شده: 86
ردیف عنوان نوع
1 In-situ optimization of thermoset composite additive manufacturing via deep learning and computer vision
بهینه سازی درجای تولید افزودنی کامپوزیت ترموست از طریق یادگیری عمیق و بینایی کامپیوتری-2022
With the advent of extrusion additive manufacturing (AM), fabrication of high-performance thermoset com- posites without the need of tooling has become a reality. However, finding an optimal set of printing parameters for these thermoset composites during extrusion requires tedious experimentation as composite ink properties can vary significantly with respect to environmental parameters such as temperature and relative humidity. Addressing this challenge, this study presents a novel optimization framework that utilizes computer vision and deep learning (DL) to optimize the calibration and printing processes of thermoset composite AM. Unlike traditional DL models where printing parameters are determined prior to printing, our proposed framework dynamically and autonomously adjusts the printing parameters during extrusion. A novel DL integrated extrusion AM system is developed to determine the optimal printing parameters including print speed, road width, and layer height for a given composite ink. This closed loop system is consisted of a computer communicating with an extrusion AM system, a camera to perform in-situ imaging and several high accuracy convolution neural net- works (CNNs) selecting the ideal process parameters for composite AM. The results show that our proposed process optimization framework was able to autonomously determine these parameters for a carbon fiber- composite ink. Consequently, specimens with complex geometries could be fabricated without visible defects and with maximum fiber alignment and thus enhancing the mechanical performance of the specimen’s com- posite material. Moreover, our proposed framework minimizes a labor-intensive procedure required to additively manufacture thermoset composites by optimizing the extrusion process without any user intervention.
keywords: یادگیری عمیق | بینایی کامپیوتر | اکستروژن | پرینت سه بعدی کامپوزیت | Deep learning | Computer vision | Extrusion | Composite 3D printing
مقاله انگلیسی
2 Defect-engineering-enhanced electrical manipulation of anisotropic excitons in two-dimensional ReS2
دستکاری الکتریکی اکسیتون های ناهمسانگرد با نقص مهندسی در ReS2 دو بعدی-2021
Engineering the photoluminescence (PL) properties, such as emission peaks, intensity, and lifetime, is highly desirable for widespread applications. Electric control is a facile and feasible method, and electrical manipulation of the PL properties with a high efficiency becomes increasingly important. ReS2 has excellent environmental stability, distinctive interlayer decoupling, and strong anisotropic properties. Herein, taking ReS2 as a prototype material, we propose a novel strategy to enhance electrical control of anisotropic excitons in ReS2 by defect engineering. Sulfur vacancies have been introduced controllably by mild argon plasma treatment, and contribute to the anisotropic defect-related exciton emission whose polarization direction is almost the same as those of the excitons along the Re–S atomic chains. However, the conversion from the neutral excitons to the defect-related excitons significantly modulate the radiation recombination behavior under a lateral electric field. The defect engineering-enhanced electrical manipulation of anisotropic excitons paves the way towards an exciton engineering in new 2D electronic and optoelectronic devices.
Keywords: Photoluminescence | Anisotropic | Defect engineering | Electric control
مقاله انگلیسی
3 Interval growth across gestation in pregnancies with fetal gastroschisis
رشد فاصله در حاملگی در حاملگی با گاستروشسیس جنین-2021
BACKGROUND: Gastroschisis is often complicated by fetal growth restriction, preterm delivery, and prolonged neonatal hospitalization. Prenatal management and delivery decisions are often based on estimated fetal weight and interval growth; however, appropriate interval growth from week to week across gestation for these fetuses is poorly understood.
OBJECTIVE: This study aimed to determine the median increase in overall estimated fetal weight and individual biometric measurements across each week of gestation in pregnancies with fetal gastroschisis and to assess whether lower in utero fetal weight gain is predictive of postnatal growth or adverse neonatal outcomes.
STUDY DESIGN: This was a retrospective cohort study of pregnancies with gastroschisis evaluated at 5 institutions of the University of California Fetal-Maternal Consortium from December 2014 to December 2019. The inclusion criteria were prenatally diagnosed gastroschisis with at least 1 ultrasound performed at a University of California Fetal-Maternal Consortium institution. Estimated fetal weight and individual biometric measurements were recorded for each ultrasound performed at a University of California Fetal-Maternal Consortium institution from the time of gastroschisis diagnosis to delivery. Median estimated fetal weight and biometric measurements were calculated for each gestational age in 1-week increments. Neonatal outcomes collected were birthweight, length of stay, complications of gastroschisis (bowel atresia, bowel stricture, ischemic bowel before closure, or severe pulmonary hypoplasia), and growth failure at discharge.
RESULTS: We identified 95 pregnancies with fetal gastroschisis who, in aggregate, had 360 growth ultrasounds at a University of California FetalMaternal Consortium institution. The median interval growth was 130 g/wk. The median estimated fetal weight and abdominal circumference in fetal gastroschisis cases were approximately the tenth percentile on the Hadlock growth curve across gestation. Moreover, the median biparietal diameter, head circumference, and femur length measurements remained below the 50th percentile on the Hadlock growth curve across gestation. The median birthweight for neonates with less than the median weekly prenatal weight gain was less than for those with greater than the median weekly prenatal weight gain (2185 g vs 2780 g; P<.01). There was no difference in prenatal weight gain trajectory when comparing neonates who had or did not have bowel complications of gastroschisis.
CONCLUSION: In this multicenter cohort of pregnancies with fetal gastroschisis, the median interval growth was 130 g/wk, and overall, in utero growth closely followed the tenth percentile on the Hadlock curve. Poor prenatal growth in cases of fetal gastroschisis correlates with lower neonatal weights but did not predict a more complicated course. Key words: abdominal wall defect | biometric parameters | fetal anomaly | fetal growth restriction | nomograms | postnatal growth
مقاله انگلیسی
4 Joint finance and order decision for supply chain with capital constraint of retailer considering product defect
تصمیم مشترک مالی و سفارش برای زنجیره تامین با محدودیت سرمایه خرده فروش با توجه به نقص محصول-2021
Small retailers usually face difficulties in obtaining bank loans due to inadequate credit history. Traditional commercial loan can be very costly or even unavailable to such retailers. In order to promote the collaboration of the supply chain to gain the mutual interest of all the parties, larger suppliers are generally willing to inter- mediate between retailers and commercial institutions. In this paper, the proper scheme and its efficiency of supplier intermediation in retailer financing are carefully investigated for the case of existing unreliable prod- ucts. By building a Stackelberg game model, we show that the supplier intermediated financing scheme can significantly improve the supply chain partners’ profits. Furthermore, with an elaborate numerical analysis, we demonstrate that the retailer will be motivated to choose the financing strategy only when the loan interest rate is less than a certain threshold. Finally, we explore how the compensation for product defect influences the supply chain partners’ optimal strategies and profits, which show that the proper compensation can realize Pareto improvement of the supply chain.
Keywords: Capital constraints | Supply chain finance | Stackelberg game
مقاله انگلیسی
5 Tuning optical and electrical properties of TixSn1−xO2 alloy thin films with dipole-forbidden transition via band gap and defect engineering
تنظیم خواص نوری و الکتریکی لایه های نازک آلیاژ TixSn1-xO2 با انتقال دوقطبی ممنوع از طریق شکاف باند و مهندسی نقص-2021
We investigated the optical, electrical properties and electronic band structures of band gap tunable TixSn1−xO2 alloy with dipole-forbidden transition. TixSn1−xO2 alloy thin films with various Ti concentrations (0 ≤ x ≤ 0.36) were fabricated on quartz substrate by sol-gel method. As Ti is alloyed into SnO2, the narrowing of optical band gap of TixSn1−xO2 alloy was observed in the optical absorption spectra and was supported by first-principles calculations, which differs from the widening of fundamental band gap. Hall effect measurements indicate that the electrical resistivity of the TixSn1−xO2 alloy thin films increases with the increase of Ti concentration. Comparing with the pure SnO2, the TixSn1−xO2 alloy thin films exhibit a strong deep-level emission associated to oxygen vacancy (VO) defects in the photoluminescence spectra. First-principles calculation results suggest that the formation energy of TiSn-VO complex defect in a TixSn1−xO2 alloy is lower than that of the single VO in a perfect SnO2 under both oxygen-rich and oxygenpoor conditions. Especially, under the oxygen-poor limit, the TiSn-VO complex defect has the lowest formation energy among several major point defects of SnO2. Our results suggest that the band gap engineering of TixSn1−xO2 can not only control the band gap, but also modulate the defects, thus tuning the electrical and optical properties, which is of great significance for the understanding of the nature of electronic band structure of TixSn1−xO2 alloys.
Keywords: Tin dioxide | Thin film | Dipole-forbidden transition | Band gap engineering | First-principle calculation
مقاله انگلیسی
6 Elucidating the influence of native defects on electrical and optical properties in semiconducting oxides: An experimental and theoretical investigation
تبیین تأثیر عیوب بومی بر خواص الکتریکی و نوری در اکسیدهای نیمه رسانا: یک بررسی تجربی و نظری-2021
Defect engineering using self-doping or creating vacancies in polycrystalline oxide based materials has profound influence on optical absorption, UV photo detection, and electrical switching. However, defects induced semiconducting oxide devices show enhancement in photo detection and photosensitivity, and hence still remain interesting in the field of optoelectronics. In this study, defect engineering in semiconducting oxide materials is discussed along with their roles in optoelectronic device-based applications. Theoretical investigations have been done for identifying defect states by performing first-principles electronic structure calculations, employing the density-functional theory. Particularly, in this work we have focused on probing the defect-induced changes in optical and electrical processes by means of experimental as well as computational investigations. Hence, systematic experimental measurements of optical absorption, electrical switching, charge density, and photocurrent in defect-rich semiconducting oxide samples have been performed. Our results suggest that defects can lead to enhancement of optoelectronic properties such as photocurrent, switching speed, optical absorption etc. for semiconducting oxide based devices.
Keywords: Semiconducting oxides | Photocurrent | Defects | Optical absorption | Charge analysis
مقاله انگلیسی
7 Evaluation of factors contributing to the failure of information systems in public universities: The case of Iran
ارزیابی عوامل مؤثر در عدم موفقیت سیستمهای اطلاعاتی در دانشگاههای دولتی: پرونده ایران-2020
In this paper, we evaluate the reasons for the failure of information systems in public universities. To that end, we start by presenting a hierarchical structure of criteria after reviewing related studies, and dividing the criteria into the categories of project management, organizational management, human- related, organizational and technical. To assess the weight of the criteria in the proposed framework, we collect the opinions of a sample of information technology experts working in different public universities in Iran, using an online questionnaire that is based on the best–worst method (BWM). By analyzing the weight of the criteria, we can reveal that misfit of information systems software (closely followed by lack of top management support and unsuccessful monitoring and measurement) has the greatest impact on the failure of information systems in the public universities of Iran. The methodology proposed in this paper can be used in other countries facing the same problem.
Keywords: Failures of information systems | Public universities | Best–worst method | BWM
مقاله انگلیسی
8 الگوریتم تکاملی چند هدفه مبتنی بر شبکه عصبی برای زمانبندی گردش کار پویا در محاسبات ابری
سال انتشار: 2020 - تعداد صفحات فایل pdf انگلیسی: 16 - تعداد صفحات فایل doc فارسی: 45
زمانبندی گردشکار یک موضوع پژوهشی است که به طور گسترده در محاسبات ابری مورد مطالعه قرار گرفته است و از منابع ابری برای کارهای گردش کار استفاده می¬شود و برای این منظور اهداف مشخص شده در QoS را لحاظ می¬کند. در این مقاله، مسئله زمانبندی گردش کار پویا را به عنوان یک مسئله بهینه سازی چند هدفه پویا (DMOP) مدل می¬کنیم که در آن منبع پویایی سازی بر اساس خرابی منابع و تعداد اهداف است که ممکن است با گذر زمان تغییر کنند. خطاهای نرم افزاری و یا نقص سخت افزاری ممکن است باعث ایجاد پویایی نوع اول شوند. از سوی دیگر مواجهه با سناریوهای زندگی واقعی در محاسبات ابری ممکن است تعداد اهداف را در طی اجرای گردش کار تغییر دهد. در این مطالعه یک الگوریتم تکاملی چند هدفه پویا مبتنی بر پیش بینی را به نام الگوریتم NN-DNSGA-II ارائه می¬دهیم و برای این منظور شبکه عصبی مصنوعی را با الگوریتم NGSA-II ترکیب می¬کنیم. علاوه بر این پنج الگوریتم پویای مبتنی بر غیرپیش بینی از ادبیات موضوعی برای مسئله زمانبندی گردش کار پویا ارائه می¬شوند. راه¬حل¬های زمانبندی با در نظر گرفتن شش هدف یافت می¬شوند: حداقل سازی هزینه ساخت، انرژی و درجه عدم تعادل و حداکثر سازی قابلیت اطمینان و کاربرد. مطالعات تجربی مبتنی بر کاربردهای دنیای واقعی از سیستم مدیریت گردش کار Pegasus نشان می¬دهد که الگوریتم NN-DNSGA-II ما به طور قابل توجهی از الگوریتم¬های جایگزین خود در بیشتر موارد بهتر کار می¬کند با توجه به معیارهایی که برای DMOP با مورد واقعی پارتو بهینه در نظر گرفته می¬شود از جمله تعداد راه¬حل¬های غیرغالب، فاصله¬گذاری Schott و شاخص Hypervolume.
مقاله ترجمه شده
9 Street harassment is marketplace discrimination: The impact of street harassment on young female consumers’ marketplace experiences
آزار و اذیت خیابانی تبعیض در بازار است: تأثیر آزار و اذیت خیابانی بر تجارب بازار مصرف کنندگان زن جوان-2020
This study brings street harassment to the retailing and consumer services literature streams. Street harassment describes unwanted interactions in public spaces between strangers or customers and is often motivated by a person’s gender, sexual orientation, or gender expression. To date, marketers have overlooked the occurrence of street harassment in retail establishments and consumer service domains, such as in theaters, public markets, recreational areas, and shopping malls. This work empirically demonstrates the extent to which young women in Nepal experience harassment from men in the marketplace and the various tactics they employ to lessen it. Furthermore, this research exposes the extent to which Nepali men admit to participating in verbal, physical, or visual harassment of women in various retailing and service settings. The article concludes with a discussion of theoretical, managerial, and societal implications and encourages public policy officials to treat street harassment as a criminal offense.
Keywords: Street harassment | Place avoidance | Discrimination | Service inclusion | Transformative service research | Pink services
مقاله انگلیسی
10 A Systematic Study on BEOL Defectivity Control for Future AI Application
یک مطالعه سیستماتیک در مورد کنترل نقص BEOL برای کاربرد هوش مصنوعی در آینده-2020
In this paper, a case study on control of BEOL defectivity in a systematic way for the future AI application is presented. A few novel methodologies were introduced to identify the source of defectivity in various BEOL sectors, such as, patterning, barrier deposition, plating, and CMP. We successfully reduced the defectivity to the level required to yield target AI devices.
Keywords: BEOL | defectivity control | AI application
مقاله انگلیسی
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