单馈圆极化天线等效电路轴比与反射系数关系研究

基于腔模理论本文提出了理想单馈圆极化天线的等效电路,并且给出了轴比参数和反射系数的计算公式,同时推导得到了单馈圆极化天线等效电路轴比与反射系数关系。从而实现利用电路参数计算得到的反射系数来预估轴比曲线参数的目的。将结果与电路参数计算得到的轴比进行对比,验证了结论的正确性。     

Public procurement for innovation through supplier firms' sustainability lens: A systematic review and research agenda

Public sector purchasing processes are gaining increasing prominence as a demand-side innovation tool for addressing national sustainability challenges. Accordingly, there has been growing research attention to this topic. Prior studies suggest three key rationales that underlie the use of public sector procurement to drive innovation: (i) the buyer–user rationale (for creating new needs); (ii) the market/system failure rationale (for improving suppliers' capacity to innovate); and (iii) the public services rationale (for improving public services). However, operational activities at the upstream supply chain affecting the sustainable innovation capacities of supplier firms appear to be under-researched in the public procurement for innovation (PPI) scholarship, despite knowledge about innovation capacity being critical to successfully implementing PPI. This paper adopts a systematic literature review approach to synthesise existing fragmented literature on sustainability-oriented PPI, focusing on supplier perspectives. Findings from a synthesis of 41 relevant articles suggest, among others conditions, that a procurement framework that maintains a good balance of competition and innovation, builds buyer–supplier relationship and urges strong supply networks, maintains a stable political commitment, offers security for niche markets with effective innovation risk management culture would enhance suppliers' sustainability capacity and propensity to innovate. This paper contributes to the PPI literature and the literature on determinants of sustainable innovation systems from supplier firms' sustainability lens.     

Outsourcing logistics operations in circular economy towards to sustainable development goals

One of novel manners to achieve sustainable development is concentrating on circular economy in order to manage greenhouse gas emissions, energy consumption, and waste. It also helps to protect the environment and optimize usage of input resources. The main element of circular economy is closed-loop supply chain which covers both forward and reverse products flows. This study aims to outsource logistics operations in a closed-loop supply chain. An innovative analytical multi-step fuzzy decision-making method is proposed to rank sustainable third-party logistics service providers (3PLSPs). Fuzzy Decision-Making Trial and Evaluation Laboratory (DEMATEL) is first used to evaluate the relationships among the main criteria. Then, fuzzy analytic network process (ANP) is applied to weight the determined set of criteria. In order to develop the hybrid fuzzy DEMATEL-ANP method and to simplify the computation, the expert judgment method is used between the two techniques as a middle step to reduce the number of criteria. As many of the criteria overlap with each other on content and context, expert opinions are used to shortlist and rank the criteria. Finally, the 3PLSPs are ranked through the fuzzy complex proportional assessment (COPRAS) method. To validate the practicability and applicability of the improved decision-making model, a household appliance case study is applied with data obtained from industry experts. In this case, five service providers are considered and ranked, while the first one gets the best score. A sensitivity analysis is performed by altering the criteria weights to validate the proposed approach, data, and the obtained results. In terms business and the environment, this study provides success critical criteria for decision-making problems in circular economy for addressing sustainable development.