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ردیف | عنوان | نوع |
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51 |
Nonlinear analysis and active management of production-distribution in nonlinear supply chain model using sliding mode control theory
تحلیل غیرخطی و مدیریت فعال تولید-توزیع در مدل غیر خطی زنجیره تامین با استفاده از تئوری کنترل حالت کشویی-2021 This paper deals with system dynamics approach for dynamical behaviors and control
synthesis of supply chain system by utilizing three-stage production-distribution model.
The presented approach offers systematic tools for determining fundamental relationships
between multi-echelons in the supply chain dynamics by using eigenvalues, bifurcation,
and time history investigation. By exploring system dynamics on time series analysis, it
is found that system performance has suffered severely from the bullwhip effect under
impacts of model uncertainties and perturbed demand. The novel fractional-order sliding
mode control algorithm has been presented based on adaptation mechanism, ensuring that
the shipment flows are robustly stable in supply chain networks against disruptions. This
is a smarter way of getting sufficient strength to sustain existing competitive market for
mitigating the risks and improving the supply chain performance. The system stability has
been thoroughly analyzed by using Routh-Hurwitz criterion and Lyapunov theory. Extensive numerical simulations have been conducted to obtain insights into the system behaviors and to validate effectiveness of active control policies by matching the shipment
sent to customer demand, ensuring supply chains resilience. Finally, it is found that the
presented approach can help decision-makers develop more efficient supply chain management system against severe market disruptions. Keywords: System dynamics | Supply chain management | Production-distribution model | Fractional order | Sliding mode control | Adaptive law |
مقاله انگلیسی |
52 |
Natural vibrations and stability of loaded cylindrical shells partially filled with fluid, taking into account gravitational effects
ارتعاشات طبیعی و پایداری پوستههای استوانهای بارگذاری شده تا حدی پر از مایع، با در نظر گرفتن اثرات گرانشی-2021 The paper presents the results of studying circular cylindrical shells partially filled with an ideal liquid and
subjected to uniform external and internal hydrostatic pressure. The behavior of an elastic structure and a
compressible fluid is described in the framework of the classical nonlinear theory of shells, based on the
Kirchhoff – Love hypotheses, and the Euler equations. The problem is solved using a semi-analytical version
of the finite element method. The influence of the level of fluid in the shell on the critical values of external
pressure is analyzed with and without consideration of gravitational effects on the free and lateral surfaces
of the fluid. Shells with different boundary conditions and linear dimensions are considered. It has been
shown that for certain geometrical parameters the gravitational field can significantly affect the dynamic
characteristics of the structure.
Keywords: Classical shell theory | Ideal compressible fluid | Finite element method | Gravitational field | Natural vibrations | Stability |
مقاله انگلیسی |
53 |
Factors that account for the wealth inequality differences between post-socialist countries
عوامل موثر بر تفاوت های نابرابری ثروت بین کشورهای پس از سوسیالیستی-2021 In general, there are significant cross-country differences in wealth inequality. Recent research has documented
that household socio-economic characteristics do not explain these differences across advanced economies. Thus,
this study is the first to examine the determinants of such disparities in wealth inequality between five postsocialist emerging markets of Central and Eastern Europe (CEE). Based on the findings, the differences in
homeownership rates accounted for up to 42% of the cross-country disparities in wealth inequality (when
measured with the Gini index) and for as much as 63%–109% of wealth inequalities in the bottom part of the
distribution. However, our results are not sensitive to the significant underestimation of top wealth values
observed in household survey data. We argue that the differences in homeownership rates among the CEE
countries are related, among others, to varying government support for mortgage loans before the global financial
crisis (2003–2007) and the degree of government help for indebted households after the crisis.
keywords: نابرابری ثروت | تجزیه | مرکزی و شرقی اروپا (CEE) | مالکیت خانه | گمشده غنی | Wealth inequality | Decomposition | Central and Eastern Europe (CEE) | Homeownership | Missing rich |
مقاله انگلیسی |
54 |
Biometric traits of onion ( Allium cepa L:) exposed to 137Cs and 243Am under hydroponic cultivation
صفات بیومتریک پیاز (Allium cepa L:) در معرض 137 درجه سانتیگراد و 243 آمپر در زیر کشت هیدروپونیک-2021 ≈ ≈≈ ≈To elucidate the features of bioaccumulation and phytotoxic effects of long-lived artificial radionuclides, a hydroponic experiment was carried out with the cultivation of onion (Allium cepa L.) in low-mineralized solutions spiked with 137Cs (250 kBq L—1) or 243Am (9 kBq L—1). After the 27-day growth period, 70% of 137Cs and 14% of 243Am were transferred from the solutions to onion biomass with transfer factor values 400 and 80, respectively. Since the bioaccumulation of both radionuclides mainly took place in the roots of onion (77% 137Csand 93% 243Am of the total amount in biomass), edible organs – bulbs and leaves – were protected to some extent from radioactive contamination. At the same time, the incorporation of the radionuclides into the root tissues caused certain changes in their biometric (geometric and mass) traits, which were more pronounced under the243Am-treatment of onion. Exposure to 243Am significantly reduced the number, length, and total surface area of onion roots by 1.3–2.6 times. Under the influence of 137Cs, the dry-matter content in roots decreased by 1.3 times with a corresponding increase in the degree of hydration of the root tissues. On the whole, the data obtained revealed the specific features of 137Cs and 243Am behaviour in “hydroponic solution – plant” system and suggested that biometric traits of onion roots could be appropriate indicators of phyto(radio)toxicity. Keywords: Radionuclides | Bioaccumulation | Root uptake | Transfer factor | Root–to–shoot translocation | Phytotoxicity |
مقاله انگلیسی |
55 |
Criteria for effective regional scale catchment to reef management: A case study of Australias Great Barrier Reef
معیارهای حمل و نقل موثر منطقه ای به مدیریت ریف: مطالعه موردی صخره های بزرگ مانع استرالیا-2021 Many coastal and marine ecosystems around the world are under increasing threat from a range of anthropogenic
influences. The management of these threats continues to present ongoing challenges, with many ecosystems
increasingly requiring active restoration to support or re-establish the ecosystems biological, cultural, social and
economic values. The current condition of Australias Great Barrier Reef (GBR) and its threats, including water
quality, climate change and the loss of wetlands, causing the continuing decline in the GBRs ecological condition
and function, has received global attention. Activities aimed at halting these declines and system restoration have
been underway for over forty years. These activities are challenging to implement, and much has been learnt
from their various outcomes. This paper considers the GBR and the associated management activities as a case
study for regional scale catchment to reef management. It summarises the management approaches to date,
describing the key role that science, policy and community have played in underpinning various investments.
Four criteria for success are proposed: the lead role of the community, the need for a systems approach, the need
for targeted, cost-effective and sustainable long-term investment, and importantly, building knowledge and
maintaining consensus and political commitment. keywords: سیستم های زیست محیطی | تنوع زیستی | حوضه | سواحل | اقیانوس ها | انجمن | تعمیر | انعطاف پذیری | ریف بزرگ مانع | Ecological systems | Biodiversity | Catchments | Coasts | Oceans | Community | Repair | Resilience | Great Barrier Reef |
مقاله انگلیسی |
56 |
An automated deep learning based anomaly detection in pedestrian walkways for vulnerable road users safety
یک تشخیص ناهنجاری مبتنی بر یادگیری عمیق در معابر پیاده برای ایمنی کاربران جاده ای آسیب پذیر-2021 Anomaly detection in pedestrian walkways is an important research topic, commonly used to improve the safety of pedestrians. Due to the wide utilization of video surveillance systems and the increased quantity of captured videos, the traditional manual examination of labeling abnormal events is a tiresome task. So, an automated surveillance system that detects anomalies becomes essential among computer vision researchers. Presently, the development of deep learning (DL) models has gained significant interest in different computer vision processes namely object classification and object detection, and these applications were depending on supervised learning that required labels. Therefore, this paper develops an automated deep learning based anomaly detectiontechnique in pedestrian walkways (DLADT-PW) for vulnerable road user’s safety. The goal of the DLADT-PWmodel is to detect and classify the various anomalies that exist in the pedestrian walkways such as cars, skating, jeep, etc. The DLADT-PW model involves preprocessing as the primary step, which is applied for removing the noise and raise the quality of the image. In addition, mask region convolutional neural network (Mask-RCNN) with densely connected networks (DenseNet) model is employed for the detection process. To ensure the better anomaly detection performance of the DLADT-PW technique, an extensive set of simulations were performed and the outcomes are investigated under distinct aspects. The obtained experimental values confirmed the superior characteristics of the DLADT-PW technique by achieving a maximum detection accuracy. Keywords: Anomaly detection | Pedestrian walkways | Deep learning | Safety | Mask RCNN |
مقاله انگلیسی |
57 |
Big data management capabilities and librarians innovative performance: The role of value perception using the theory of knowledge-based dynamic capability
قابلیت های مدیریت داده های بزرگ و عملکرد نوآورانه کتابداران: نقش ادراک ارزش با استفاده از تئوری قابلیت پویایی مبتنی بر دانش-2021 This study extended the concept of knowledge-based dynamic capabilities from a firm level to individual level
and investigated the relationship between big data management capabilities and innovative performance of
university librarians in selected Ghanaian universities. The role of big data value perception as a mediator was
also assessed using the PLS-SEM. Data were validated with Cronbach’s alpha above 0.8 and with factor analysis
and further convergent and discriminant validity tests. AVE values were higher than 0.5 and CR above AVE and
discriminant validity test scores below 0.6. Statistical significance was at a P-value of 0.05. Knowledge-based
dynamic capabilities (KDC) were found not to have a direct significant influence on innovative performance
(IP) (r2 = 0.109) of librarians. However, KDC positively influenced the perceived value for big data management
(BDVP) (r2 = 0.674) with the later having a significant effect on the innovative performance of librarians (r2 =
0.777). BDVP among librarians was found to significantly mediate the relationship between KDC and IP such that
KDC indirectly recorded a higher path coefficient (r2 = 0.524) than its initial direct effect of 0.109. Library
managers and librarians are encouraged to develop big data management capability of staff to help create
positive perceptions about the relevance of the field to enhance innovation and improved performance. keywords: توانایی پویا مبتنی بر دانش | عملکرد نوآورانه | مدیریت داده های بزرگ | کتابخانه ها | علم اطلاعات | Knowledge-based dynamic capability | Innovative performance | Big data management | Libraries | Information science |
مقاله انگلیسی |
58 |
Double accounting in energy footprint and related assessments: How common is it and what are the consequences?
حسابداری دوگانه در ارزیابی انرژی و ارزیابی های مرتبط: چقدر رایج است و پیامدهای آن چیست؟-2021 The number of input-output assessments focused on energy has grown considerably in the last years.
Many of these assessments combine data from multi-regional input-output (MRIO) databases with energy extensions that completely or partially depict the different stages through which energy products
are supplied or used in the economy.
The improper use of some energy extensions can lead to double accounting of some energy flows, but the frequency with which this happens and the potential impact on the results are unknown. Based on a literature review, we estimate that around a quarter of the MRIO-based energy assessments reviewed incurred into double accounting. Using the EXIOBASE MRIO database, we also analyse the effects of double accounting in the absolute values and rankings of different countries’ and products’ energy footprints. Building on the insights provided by our analysis, we offer a set of key recommendations to MRIO users to avoid the double accounting problem in the future. Likewise, we conclude that the harmonisation of the energy data across MRIO databases led by experts could simplify the choices of the data users until the provision of official energy extensions by statistical offices becomes a widespread practice. keywords: تجزیه و تحلیل ورودی خروجی | مایه | رد پای انرژی | پسوند انرژی | حسابداری دوگانه | استفاده از انرژی | Input-output analysis | MRIO | Energy footprint | Energy extensions | Double accounting | Energy use |
مقاله انگلیسی |
59 |
Colour assessment of milk and milk products using computer vision system and colorimeter
ارزیابی رنگ شیر و فرآورده های شیر با استفاده از سیستم بینایی ماشین و رنگ سنج-2021 A computer vision system (CVS) and a colorimeter were compared for their abilities to measure the colour of twenty-seven different milks and milk products. The frequency of similarity test showed that CVS-generated colour chips were similar to the actual sample colour in all trials (100%). The CVS- obtained colours were found to be more similar to the colour of sample visualised on the monitor, compared with colorimeter-generated colour chips, with values of 83.3e100.0% depending on the milk product. The third test showed that there was difference between colour measured by CVS and the colorimeter; colorimeter readings resulted in a darker and yellower colour based on average L*a*b* values, while CVS readings resulted in lighter and less yellow appearance. Compared with a colorimeter, measuring colour by CVS was, therefore, found to be reliable and should be considered as a superior tool for replacing traditional devices by offering improved representativeness and accuracy.© 2021 Elsevier Ltd. All rights reserved. |
مقاله انگلیسی |
60 |
Accounting for uncertainties due to high-impact low-probability events in power system development
محاسبه عدم قطعیت های ناشی از رویدادهای با احتمال کم تاثیر زیاد در توسعه سیستم قدرت-2021 In the long-term development of the electric power system, system operators should consider the socio-economic
balance between grid investment costs and security of supply, including the risk of power supply interruptions.
Cost-benefit analyses conducted for this purpose are associated with many uncertainties but have traditionally
focused on the expected value of the net socio-economic benefits of risk-reducing measures. This article focuses
on the large uncertainties that are associated with the possible occurrence of high-impact low-probability
interruption events (HILP events). The objective is to quantify and visualize the implications of uncertainties due
to HILP events in the context of power system development. More specifically, this article describes a method-
ology accounting for uncertainties in socio-economic cost-benefit analysis of measures for reducing the risk of
HILP events. The methodology accounts for the contributions of both aleatory and epistemic uncertainties and
comprises a hybrid probabilistic-possibilistic uncertainty analysis method. Applying the methodology to a real
case involving a grid investment decision, it is demonstrated how it provides additional insight compared to
conventional cost-benefit analyses considering expected values where uncertainties are not accounted for
explicitly. It is furthermore discussed how these results can help to better inform grid development decisions. keywords: برنامه ریزی سیستم قدرت | تحلیل ریسک | آسیب پذیری | قابلیت اطمینان سیستم قدرت | رویدادهای فوق العاده | Power system planning | Risk analysis | Vulnerability | Power system reliability | Extraordinary events |
مقاله انگلیسی |