Salvatore Cannella  Elena Ciancimino 《国际生产研究杂志》2013,51(22):6739-6776

This paper provides an assessment of the impact of collaboration and smoothing replenishment rules on supply chain operational performance and customer service level. Three supply chain configurations (i.e. Traditional, Information Exchange and Synchronised) in which orders are generated by smoothing (S, R) inventory control policies are studied for different proportional controllers. A supply chain stress test is performed through a sudden and intense change in demand. A structured and extended supply chain assessment framework is adopted. The main conclusions of this paper are the following. (i) The impact of Supply Chain Collaboration on overall supply chain performance is greater than that of order smoothing. Order smoothing mitigates the bullwhip effect, but it may have a negative impact on customer service. Supply Chain Collaboration mitigates the bullwhip effect, provides inventory stability, limits lumpy orders and enhances customer service level. (ii) The negative effect on customer service level of order smoothing is almost eliminated in synchronised supply chains.  相似文献   

    

Vignesh T. Subrahmaniam  Anup Dewanji  Bimal K. Roy 《技术计量学》2015,57(4):576-585

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Bruce E. Dale 《Biofuels, Bioproducts and Biorefining》2007,1(1):14-17

As the world shifts away from a dependency on petroleum resources it is imperative that clear and accurate perceptions of the value of alternative fuel sources are recognized. The silly “net energy” argument revolving around fuel ethanol offers a textbook example of how not to think about alternative fuels. For over 25 years a small but vocal group of critics has argued that ethanol from corn has a negative net energy. This viewpoint has been widely disseminated and is a major perceived drawback to ethanol. Net energy analysis is simple and has great intuitive appeal. It is also dead wrong and dangerously misleading. If we are to make wise decisions as we embark on this brave new world of alternative fuels, we will need to carefully choose our metrics of comparison. Two complementary metrics suggest themselves. First, alternative fuels (e.g. ethanol) can be rated on their ability to displace petroleum; and second, ethanol could be rated on the total greenhouse gases produced per km driven. These are appropriate metrics, though there is still room for more discussion. Useless, misleading and dangerous metrics such as net energy must be eliminated from our discourse. © 2007 Society of Chemical Industry and John Wiley & Sons, Ltd  相似文献   

    

《Food Control》2015

In this concept paper, we have developed three case scenarios to illustrate how one can derive a Microbiological Criterion (MC) from a Performance Objective (PO) or from a Food Safety Objective (FSO). In the first scenario, we show how one can derive an MC from a PO that is set as a numerical limit to the concentration of a pathogen. In the second scenario, it is shown how one can derive an MC from a PO that is set as the limit to the prevalence or proportion of a microorganism. In the final scenario, we show how to derive an MC from an FSO for a product supporting growth of the target pathogen between the PO and FSO. These case scenarios present guidance on how to derive an MC from risk-based metrics and very explicitly detail all the steps to be taken and assumptions/decisions that need to be made. In all three cases, MCs could successfully be established, but to do so required specific data, assumptions and decisions, as appropriate.  相似文献   

    

Xuegang Duan;Zelin Cao;Kaikai Gao;Wentao Yan;Siyu Sun;Guangdong Zhou;Zhenhua Wu;Fenggang Ren;Bai Sun; 《Advanced materials (Deerfield Beach, Fla.)》2024,36(14):2310704

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《International Journal of Hydrogen Energy》2021,46(63):31952-31962

Vanadium redox flow battery (VRFB) is the best choice for large-scale stationary energy storage, but its low energy density affects its overall performance and restricts its development. In order to improve the performance of VRFB, a new type of spiral flow field is proposed, and a multi-physics coupling model and performance metrics evaluation system are established to explore the electrolyte distribution characteristics. The results show that the new spiral flow field can effectively improve the uniformity of electrolyte flow and alleviate the phenomenon of local concentration polarization as compared with the traditional serpentine flow field and parallel flow field. Due to the long flow channel and large pressure drop, the system efficiency is low. However, coulombic efficiency, voltage efficiency and energy efficiency are significantly better than the traditional flow fields. Therefore, the novel flow field has obvious advantages in the application of small stacks.  相似文献   

    

《Signal Processing: Image Communication》2021

Objective quality assessment of digital holograms has proven to be a challenging task. While prediction of perceptual quality of the recorded 3D content from the holographic wavefield is an open problem; perceptual quality assessment from content after rendering, requires a time-consuming rendering step and a multitude of possible viewports. In this research, we use 96 Fourier holograms of the recently released HoloDB database to evaluate the performance of well-known and state-of-the-art image quality metrics on digital holograms. We compare the reference holograms with their distorted versions: (i) before rendering on the real and imaginary parts of the quantized complex-wavefield, (ii) after converting Fourier to Fresnel holograms, (iii) after rendering, on the quantized amplitude of the reconstructed data, and (iv) after subsequently removing speckle noise using a Wiener filter. For every experimental track, the quality metric predictions are compared to the Mean Opinion Scores (MOS) gathered on a 2D screen, light field display and a holographic display. Additionally, a statistical analysis of the results and a discussion on the performance of the metrics are presented. The tests demonstrate that while for each test track a few quality metrics present a highly correlated performance compared to the multiple sets of available MOS, none of them demonstrates a consistently high-performance across all four test-tracks.  相似文献   

    

K. E. Juracek  K. Eng  D. M. Carlisle  D. M. Wolock 《河流研究与利用》2017,33(7):993-1003

In the Central United States, the Arkansas darter (Etheostoma cragini) is listed as a threatened fish species by the State of Kansas. Survival of the darter is threatened by loss of habitat caused by changing streamflow conditions, in particular flow depletion. Future management of darter populations and habitats requires an understanding of streamflow conditions and how those conditions may have changed over time in response to natural and anthropogenic factors. In Kansas, streamflow alteration was assessed at 9 U.S. Geological Survey streamgages in 6 priority basins with no pronounced long‐term trends in precipitation. The assessment was based on a comparison of observed (O) and predicted expected (E) reference conditions for 29 flow metrics. The O/E results indicated a likely or possible diminished flow condition in 2 basins; the primary cause of which is groundwater‐level declines resulting from groundwater pumping for irrigated agriculture. In these 2 basins, habitat characteristics adversely affected by flow depletion may include stream connectivity, pools, and water temperature. The other 4 basins were minimally affected, or unaffected, by flow depletion and therefore may provide the best opportunity for preservation of darter habitat. Through the O/E analysis, anthropogenic streamflow alteration was quantified and the results will enable better‐informed decisions pertaining to the future management of darters in Kansas.  相似文献   

    

《International Journal of Communication Systems》2017,30(6)

There has been an escalation in deployment and research of wireless mesh networks by both the business community and academia in the last few years. Their attractive characteristics include low deployment cost, a low‐cost option to extend network coverage and ease of maintenance due to their self‐healing properties. Multiple routes exist between the sender and receiver nodes because of the mesh layout that ensures network connectivity even when node or link failures occur. Recent advances among others include routing metrics, optimum routing, security, scheduling, cross‐layer designs and physical layer techniques. However, there are still challenges in wireless mesh networks as discussed in this paper that need to be addressed. Cross‐layer design allows information from adjacent and non‐adjacent layers to be used at a particular layer for performance improvement. This paper presents a survey of cross‐layer protocol design approaches applied to the IEEE 802.11 standards for wireless multi‐hop mesh networks that have been proposed over the last few years for improved performance. We summarize the current research efforts in cross‐layer protocol design using the IEEE 802.11 standard in identifying unsolved issues that are a promising avenue to further research. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

    

Rodolfo Alvarado‐Cervantes  Edgardo M. Felipe‐Riverón  Vladislav Khartchenko  Oleksiy Pogrebnyak 《Color research and application》2017,42(2):156-172

In this article, we present an adaptive color similarity function defined in a modified hue‐saturation‐intensity color space, which can be used directly as a metric to obtain pixel‐wise segmentation of color images among other applications. The color information of every pixel is integrated as a unit by an adaptive similarity function thus avoiding color information scattering. As a direct application we present an efficient interactive, supervised color segmentation method with linear complexity respect to the number of pixels of the input image. The process has three steps: (1) Manual selection of few pixels in a sample of the color to be segmented. (2) Automatic generation of the so called color similarity image (CSI), which is a gray level image with all the gray level tonalities associated with the selected color. (3) Automatic threshold of the CSI to obtain the final segmentation. The proposed technique is direct, simple and computationally inexpensive. The evaluation of the efficiency of the color segmentation method is presented showing good performance in all cases of study. A comparative study is made between the behavior of the proposed method and two comparable segmentation techniques in color images using (1) the Euclidean metric of the a* and b* color channels rejecting L* and (2) a probabilistic approach on a* and b* in the CIE L*a*b* color space. Our testing system can be used either to explore the behavior of a similarity function (or metric) in different color spaces or to explore different metrics (or similarity functions) in the same color space. It was obtained from the results that the color parameters a* and b* are not independent of the luminance parameter L* as one might initially assume in the CIE L*a*b* color space. We show that our solution improves the quality of the proposed color segmentation technique and its quick result is significant with respect to other solutions found in the literature. The method also gives a good performance in low chromaticity, gray level and low contrast images. © 2016 Wiley Periodicals, Inc. Col Res Appl, 42, 156–172, 2017  相似文献