دانلود و نمایش مقالات مرتبط با Shock::صفحه 1
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نتیجه جستجو - Shock

تعداد مقالات یافته شده: 140
ردیف عنوان نوع
1 Preliminary lessons from COVID-19 disruptions of small-scale fishery supply chains
دروس مقدماتی مربوط به اختلالات COVID-19 در زنجیره های تامین شیلات در مقیاس کوچک-2021
The ongoing COVID-19 pandemic and associated mitigation measures have disrupted global systems that support the health, food and nutrition security, and livelihoods of billions of people. These disruptions have likewise affected the small-scale fishery (SSF) sector, disrupting SSF supply chains and exposing weaknesses in the global seafood distribution system. To inform future development of adaptive capacity and resilience in the sector, it is important to understand how supply chain actors are responding in the face of a macroeconomic shock. Comparing across seven SSF case studies in four countries, we explore how actors are responding to COVID-19 disruptions, identify constraints to adaptive responses, and describe patterns of disruption and response across cases. In all cases examined, actors shifted focus to local and regional distribution channels and particularly drew on flexibility, organization, and learning to re-purpose pre-existing networks and use technology to their advantage. Key constraints to reaching domestic consumers included domestic restrictions on movement and labor, reduced spending power amongst domestic consumers, and lack of existing distribution channels. In addition, the lack of recogni- tion of SSFs as essential food-producers and inequities in access to technology hampered efforts to continue local seafood supply. We suggest that the initial impacts from COVID-19 highlight the risks in of over-reliance on global trade networks. The SSFs that were able to change strategies most success- fully had local organizations and connections in place that they leveraged in innovative ways. As such, supporting local and domestic networks and flexible organizations within the supply chain may help build resilience in the face of future macroeconomic shocks. Importantly, bolstering financial wellbeing and security within the domestic market both before and during such large-scale disruptions is crucial for supporting ongoing supply chain operations and continued food provision during macroeconomic crises.
Keywords: Small-scale fisheries | COVID-19 | Adaptive capacity | Supply chain | Resilience | Global seafood distribution system
مقاله انگلیسی
2 COVID-19 impacts on Flemish food supply chains and lessons for agri-food system resilience
تأثیرات COVID-19 بر روی زنجیره های تأمین مواد غذایی فلاندی و درس هایی برای انعطاف پذیری سیستم کشاورزی-غذایی-2021
Context: Resilience represents the ability of systems to anticipate, withstand, or adapt to challenges. Times of great stress and disturbance offer opportunity to identify and confirm key contributors to agri-food system resilience. The COVID-19 pandemic and its related consequences constituted major shock, challenging the resilience of many agri-food systems worldwide.
Objective: This paper aimed to report the immediate effects of the COVID-19 crisis on various key actors from Flemish food supply chains. By analysing and assessing the observed impacts of and reactions to this crisis from a resilience perspective, it also aimed to gain empirical evidence on resilience-enhancing characteristics of agri-food systems to sudden shocks.
Methods: A first, quantitative step of our mixed method approach measured 718 farmers’ experienced impacts and applied strategies following the crisis through an online survey. A second, qualitative step captured impacts and responses from other key actors downstream the food supply chain through 22 in-depth interviews and 18 on-line questionnaires. Data gathering and interpretation followed a conceptual framework for analysing resilience of agri-food systems to external challenges, that we developed based on the literature. The framework states that resilience actions stem from three types of resilience capacities: anticipatory, coping and responsive capacities. These are determined by both resources allocated by system actors, as well as by resilience attributes from the system.
Results and conclusions: The COVID-19 crisis induced a simultaneous dropped demand for food products in the hospitality industry and risen demand in retail. This shifted demand significantly disturbed food production, processing and marketing processes in terms of labour organization, planning, operation, logistics, and economic returns. Perceived impacts varied extensively across actors from the agri-food system, mostly depending on their marketing strategy, customer base, and flexibility and diversity of their practices. Reported reactions to this crisis revealed that resilience capacities varied according to actors’ abilities to negotiate prices, adjust production processes, and maintain or reorient sales. Some agri-food sectors showed higher responsive capacity because of a higher connectivity and self-organization within the system.
Significance: Our findings suggest that flexibility and diversity, despite their tendency to diminish price optimums, increase resilience capacities, which may be more beneficial to systems for thriving in turbulent and uncertain environments. A more tangible, operationalized understanding of resilience is necessary to effectively improve agri-food system resilience. Our conceptual framework proved a valuable tool for operationalizing resilience assessments to major shocks.
Keywords: COVID-19 | Farmers | Resilience | Shocks | Agri-food system | Food supply chain
مقاله انگلیسی
3 An agent-based model for supply chain recovery in the wake of the COVID-19 pandemic
An agent-based model for supply chain recovery in the wake of the COVID-19 pandemic-2021
The current COVID-19 pandemic has hugely disrupted supply chains (SCs) in different sectors globally. The global demand for many essential items (e.g., facemasks, food products) has been phenomenal, resulting in supply failure. SCs could not keep up with the shortage of raw materials, and manufacturing firms could not ramp up their production capacity to meet these unparalleled demand levels. This study aimed to examine a set of congruent strategies and recovery plans to minimize the cost and maximize the availability of essential items to respond to global SC disruptions. We used facemask SCs as an example and simulated the current state of its supply and demand using the agent-based modeling method. We proposed two main recovery strategies relevant to building emergency supply and extra manufacturing capacity to mitigate SC disruptions. Our findings revealed that minimizing the risk response time and maximizing the production capacity helped essential item manufacturers meet consumers’ skyrocketing demands and timely supply to consumers, reducing financial shocks to firms. Our study suggested that delayed implementation of the proposed recovery strategies could lead to supply, demand, and financial shocks for essential item manufacturers. This study scrutinized strategies to mitigate the demand–supply crisis of essential items. It further proposed congruent strategies and recovery plans to alleviate the problem in the exceptional disruptive event caused by COVID-19.
Keywords: Risk and disruption | COVID-19 pandemic | Supply chain resilience | Essential item | Recovery strategy
مقاله انگلیسی
4 Towards a resilient food supply chain in the context of food safety
به سمت زنجیره تأمین مواد غذایی انعطاف پذیر در زمینه ایمنی مواد غذایی-2021
Global food supply chains have been constantly challenged by various food safety incidents or crisis. Traditional approaches on enhancing robustness of the food supply chain are not sufficient to ensure a safe food supply to the society, while building resilience as a more comprehensive approach has shown to be a good alternative option. With a resilience thinking, the food supply chain is not targeting to achieve a state of zero food safety risks, but rather to pursue the capacity to adapt and manage food safety shocks. A resilient food supply chain can still be vulnerable under the constant pressure of food safety hazards and the changing food chain environment, but has the capacity to adapt to and recover from the shocks. This study aimed to1) provide a clear definition for resilient food supply chains in the context of food safety; 2) provide a procedure to assess food safety resilience; 3) specify how a resilient food supply chain can be quantified and improved by providing a numerical example in a case study. Three dimensions of resilience factors, being time, degree of impacts caused by the food safety shocks, and degree of recovery, are suggested for assessing supply chain resilience. Results of a case study on Salmonella spp. in the pork supply chain show that the proposed framework and modelling allow for selecting the most effective strategies (having alternative suppliers, enhancing animal resilience as examples for the considered case) for improving the resilience of the supply chain for food safety.
Keywords: Resilience | Framework | Quantification | Risk | Hazards | Modelling
مقاله انگلیسی
5 A pressure- or velocity-dependent acceleration rate law for the shock-to-detonation transition process in PBX 9502 high explosive
قانون میزان شتاب فشار یا وابسته به سرعت برای روند انتقال شوک به انفجار در مواد منفجره PBX 9502-2020
Shock-to-detonation transition profiles of PBX 9502 explosive are analyzed to develop a rate law for shock acceleration. The shock motion profiles are seen to follow a common trend in the shock acceleration–velocity frame, aside from an early time transient that is dependent on the initiating shock strength. The duration of the early time transient is seen to correlate with the initial shock strength. The com- mon shock acceleration profile is seen to be Arrhenius-like with respect to the local particle velocity or pressure. A dual-rate pressure-dependent Arrhenius-type rate law is developed with the duration of the early rate set by the initial shock strength. The rate law is able to predict the shock motion for all tests well in both particle velocity and pressure space. In addition to directly measuring commonalities in the acceleration profiles of the experimental shock motion, this work provides insight into the functional form of the reaction rate laws for this TATB-based high explosive. The rate law also supports the concept that shock-driven reaction in heterogenous high explosives is driven by localized ignition and growth of hotspots.
Keywords: Detonation | Shock-to-detonation | transition SDT | Detonation reaction rate | High explosive
مقاله انگلیسی
6 A Hermite WENO scheme with artificial linear weights for hyperbolic conservation laws
یک طرح هرمیت WENO با وزن خطی مصنوعی برای قوانین حفاظت از hyperbolic-2020
In this paper, a fifth-order Hermite weighted essentially non-oscillatory (HWENO) scheme with artificial linear weights is proposed for one and two dimensional hyperbolic conservation laws, where the zeroth-order and the first-order moments are used in the spatial reconstruction. We construct the HWENO methodology using a nonlinear convex combination of a high degree polynomial with several low degree polynomials, and the associated linear weights can be any artificial positive numbers with only requirement that their summation equals one. The one advantage of the HWENO scheme is its simplicity and easy extension to multi-dimension in engineering applications for we can use any artificial linear weights which are independent on geometry of mesh. The another advantage is its higher order numerical accuracy using less candidate stencils for two dimensional problems. In addition, the HWENO scheme still keeps the compactness as only immediate neighbor information is needed in the reconstruction and has high efficiency for directly using linear approximation in the smooth regions. In order to avoid nonphysical oscillations nearby strong shocks or contact discontinuities, we adopt the thought of limiter for discontinuous Galerkin method to control the spurious oscillations. Some benchmark numerical tests are performed to demonstrate the capability of the proposed scheme.
Keywords: Hermite WENO scheme | Hyperbolic conservation laws | Unequal size spatial stencil | Hybrid | Discontinuous Galerkin method
مقاله انگلیسی
7 تعیین کمیت اثر سرریز در بازار ارز دیجیتال (کریپتوکارنسی)
سال انتشار: 2020 - تعداد صفحات فایل pdf انگلیسی: 10 - تعداد صفحات فایل doc فارسی: 18
این مطالعه، اثر سرریز را در بازار ارز دیجیتال با استفاده از مدل اتورگرسیو بردار بیزی پنجره لغزنده تعیین می‌کند. مطالعه‌ی حاضر، درک بهتری از ارتباطات داخلی (در هم تنیدگی) و انتقال شوک در بازار ارز مجازی ارائه می‌دهد و مقدار ریسک سرریز را در سطح جهت دار جفتی را تعیین می‌کند و درک پویایی از نوسانات شوک در بازار ارائه می‌دهد که به نوبه‌ی خود دوره‌های ادغام ریسک را مشخص می‌کند. علاوه بر این، مطالعه‌ی حاضر، عوامل تعیین کننده شوک سرریز را در بازار ارز مجازی بررسی می‌کند و ارتباطات افزایش را به محرک‌های خارجی در طول زمان نشان می‌دهد.
کلمات کلیدی: ارز رمزی | بیت کوین | ریسک سرریز | در هم تنیدگی VAR بیزی
مقاله ترجمه شده
8 Economic feasibility valuing of deep mineral resources based on risk analysis: Songtao manganese ore - China case study
ارزیابی امکان سنجی اقتصادی منابع معدنی عمیق بر اساس ریسک تجزیه و تحلیل: سنگ معدن منگنز Songtao - مطالعه موردی چین-2020
The exploitation of deep mineral resources is an inevitable choice under economic development and resource shortage. Assessing the economic feasibility of deep mineral resource exploit projects is a prerequisite for resource industry development. Mining industry have some problems influence its economic feasibility, including long mining period, high infrastructure investment and lack flexibility, and have risks of geology instability and economic reserve degrade. On the other hand, with the increase of the buried depth of mineral resources, some problems have intensified the uncertainty of the profit of deep resource utilization project, such as high stress, high lithology, high temperature environment, and increase of upgrading cost. Net Present Value (NPV) and Internal Rate of Return (IRR) are traditional economic evaluation means which difficult to identify and assess risks precisely. Decoupled Net Present Value (DNPV) provides an efficiency tool to separate the time value and risk cost which is helpful to finds the real value of projects. A manganese mining project which is located Guizhou province, China is analyzed, paper choices several mainly risks of influence expected revenue to analysis project feasibility based on the DNPV technology, which includes the thickness of ore body, ore grade, market price, operation cost and nature disaster. The cost of potential environmental risk (carbon emission cost) also is analyzed. Paper constructs a risk management framework by risk identify, assess and classification, and analyzes the corresponding measures to reduce risk costs. The mainly risk cost of study case from market price shock and unexpected ore grade decline, which accounting for 80% of the total risk cost. In the process of deep mineral resources exploit, effective cost control measures can reduce the risk cost to a certain extent, including improving productivity, reducing unit cost of ore, improving mine sustainability and exploration accuracy. Green mineral construction is a feasible direction of deep resource utilization. For improve the accuracy of economic feasibility evaluation of deep mineral resources utilization, further improvement is needed in the selection and construction of different risk assessment model.
Keywords: Deep mining | Risk value assess | DNPV | Risk management | Songtao manganese
مقاله انگلیسی
9 Lax-Ole˘ınik explicit formula and structure theory for balance laws
فرمول صریح و نظریه Lax-Ole˘ınik برای تعادل قوانین -2020
source term having the form  ut +f (u)x − α(t)u =0 inR×(0,∞) u(x, 0) = u0 on R × {t = 0}. Consequently, we show that the behaviour of the shock packets and the phenomenon of one shock situation is completely different when compared to equations without a source term. Moreover, contrary to the be-haviour of shock packets in conservation laws, in our situation, we show that the slope of the left boundary of the shock packet can be strictly greater than that of the right boundary.
Keywords:Balance laws | Riemann problem | Hamilton-Jacobi equation | Structure theorem | Asymptotically single shock packet | Lax-Ole˘ınik Formula
مقاله انگلیسی
10 A physics-based model and simple scaling law to predict the pressure dependence of single crystal spall strength
یک مدل مبتنی بر فیزیک و قانون مقیاس پذیری ساده برای پیش بینی وابستگی فشار از قدرت اسپل تک بلور-2020
A homogenized framework for ductile damage accounting for the effect of void growth on the thermomechanical response of single crystals under dynamic loading (CPD-FE) is developed. The current framework extends our prior work (Nguyen et al., 2017) by in- corporating the yield function of Han et al. (2013) for porous single crystals to govern the degradation of the macroscopic critical resolved shear stress. Validation of the model against direct numerical simulations shows a significant improvement in accuracy under conditions of macroscopic shear loading. The model parameters are calibrated to Kolsky bar (split-Hopkinson pressure bar) and plate impact experiments, and utilized to predict spall strength of single crystal copper in  100  orientation. Simulation results exhibit favor- able agreement with single crystal plate impact tests over a range of strain rates and shock compression pressures. These simulation results are used to further interpret previous ex- perimental observations on the rate and pressure sensitivity of spallation. Lastly, a simple analytical model for spall strength depending on the temperature, strain rate and pres- sure is proposed, which shows agreement with molecular dynamics (MD) simulations and experimental results. This analytical model of spall strength concisely captures the phys- ical mechanisms governing the effects of pressure, strain rate, and temperature on spall strength.
Keywords: Crystal plasticity | Damage | Failure | Fracture | Strain rate | Spall | Shock | Void
مقاله انگلیسی
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