Context: Since the end of 2019, the COVID-19 pandemic had a worst impact on world’s economy, healthcare, and education. There are several aspects where the impact of COVID-19 could be visualized. Among these, one aspect is the productivity of researcher, which plays a significant role in the success of an organization. Problem: There are several factors that could be aligned with the researcher’s productivity of each domain and whose analysis through researcher’s feedback could be beneficial for decision makers in terms of their decision making and implementation of mitigation plans for the success of an organization. Method: We perform an empirical study to investigate the substantial impact of COVID-19 on the productivity of researchers by analyzing the relevant factors through their perceptions. Our study aims to find out the impact of COVID-19 on the researcher’s productivity that are working in different fields. In this study, we conduct a questionnaire-based analysis, which included feedback of 152 researchers of certain domains. These researchers are currently involved in different research activities. Subsequently, we perform a statistical analysis to analyze the collected responses and report the findings. Findings: The results indicate the substantial impact of COVID-19 pandemics on the researcher’s productivity in terms of mental disturbance, lack of regular meetings, and field visits for the collection of primary data. Conclusion: Finally, it is concluded that researcher’s daily or weekly meetings with their supervisors and colleagues are necessary to keep them more productive in task completion. These findings would help the decision makers of an organization in the settlement of their plan for the success of an organization. 相似文献
Protonic ceramic fuel cells (PCFCs) can use hydrogen and hydrocarbon fuels to generate electricity with good performance and anti-cooking resistance. Herein, a novel dual-phase perovskite oxide BaCe0.5Fe0.4Ni0.1O3-δ (BCFN) with BaCe0.5Fe0.5O3-δ (BCF) as one reference was synthesized, characterized and then evaluated as the symmetrical electrodes for PCFCs. Both BCF and BCFN can be self-assembled into an orthorhombic cerium-rich oxide phase and a cubic iron-rich oxide phase after calcined at 1000 °C and show good redox stability. BCFN shows much better electrical conductivity and lower area specific resistance than BCF. Applying BCF and BCFN as symmetrical electrodes for PCFCs with the BaZr0.1Ce0.7Y0.2O3-δ (BZCY) electrolyte supporting, the cell performance with BCFN symmetrical electrode is almost twice (141 mW·cm2 at 700 °C) than those with BCF symmetrical electrode, and the electrode polarization resistances are also reduced from 0.7 to 0.5 Ω·cm2 using humidified H2. The preliminary experimental results can demonstrate that dual-phase perovskite oxides with nanoparticle in situ precipitation are very promising symmetrical electrodes for protonic ceramic fuel cells.
For the first time, the brittle fracture of epoxy‐based nanocomposite reinforced with MWCNTs (multi‐walled carbon nanotubes) and subjected to mixed mode II/III loading conditions is investigated. This experimental investigation is carried out using a newly developed test configuration. Araldite LY 5052 epoxy, which is a resin frequently used in aerospace industry, is utilized to fabricate pure epoxy and nanocomposite test specimens with two different MWCNTs contents of 0.1 and 0.5 wt%. The obtained experimental results reveal that adding MWCNTs to epoxy resin up to 0.5 wt% improves the fracture toughness under pure mode II and pure mode III loading with an increasing trend. This is while the improvement under mixed mode II/III loading is reduced by adding nanotubes more than 0.1 wt%. To justify the variations of fracture toughness in terms of nanoparticles content, SEM (scanning electron microscopy) photographs of the fracture surfaces of the specimens in the vicinity of the initial crack front are prepared. Additional fracture mechanisms caused by adding carbon nanotubes are discussed in detail based on the provided SEM images. 相似文献
AbstractIn this work, three different arrangements of circuit board in an electronic device were designed and the effects of random vibration frequencies on the reliability of ball grid arrays (BGA) in these arrangements were evaluated. The failure criterion in solder balls was the root mean square of peeling stress exerted during the dynamical loadings. According to the finite element method (FEM) results, the uttermost stress concentration was generated at the interface of printed circuit board (PCB) and the solder balls. It was also revealed that the increase of input power spectral density (PSD) decreased the fatigue life of solder joint in all the arrangements. Considering the arrangements of circuit boards, it was found that the maximum domain of peeling stress had a minimum effect on the solder balls when the heat sinks were away from the packages. The microstructural characterization of critical zone in solder balls indicated that with the increase of maximum peeling stress, the crack initiated and propagated along the interface. 相似文献
This paper uses Kharitonov's theorem to present a new idea for assessment of the stability of linear systems that are described by fuzzy differential equations, while system uncertainty is expressed as fuzzy convex sets for coefficients of the characteristic equation. The paper then deals with determination of stability margins and the design of classical robust controllers of fuzzy type for those systems. In each part, illustrative examples and simulation results are provided. 相似文献
In this paper a new fuzzy Multidimensional Multiple-choice Knapsack Problem (MMKP) is proposed. In the proposed fuzzy MMKP, each item may belong to several groups according to a predefined fuzzy membership value. The total profit and the total cost of the knapsack problem are considered as two conflicting objectives. A mathematical approach and a heuristic algorithm are proposed to solve the fuzzy MMKP. One method is an improved version of a well-known exact multi-objective mathematical programming technique, called the efficient ?-constraint method. The second method is a heuristic algorithm called multi-start Partial-Bound Enumeration (PBE). Both methods are used to comparatively generate a set of non-dominated solutions for the fuzzy MMKP. The performance of the two methods is statistically compared with respect to a set of simulated benchmark cases using different diversity and accuracy metrics. 相似文献
Cooperation in learning (CL) can be realized in a multiagent system, if agents are capable of learning from both their own experiments and other agents' knowledge and expertise. Extra resources are exploited into higher efficiency and faster learning in CL as compared to that of individual learning (IL). In the real world, however, implementation of CL is not a straightforward task, in part due to possible differences in area of expertise (AOE). In this paper, reinforcement-learning homogenous agents are considered in an environment with multiple goals or tasks. As a result, they become expert in different domains with different amounts of expertness. Each agent uses a one-step Q-learning algorithm and is capable of exchanging its Q-table with those of its teammates. Two crucial questions are addressed in this paper: "How the AOE of an agent can be extracted?" and "How agents can improve their performance in CL by knowing their AOEs?" An algorithm is developed to extract the AOE based on state transitions as a gold standard from a behavioral point of view. Moreover, it is discussed that the AOE can be implicitly obtained through agents' expertness in the state level. Three new methods for CL through the combination of Q-tables are developed and examined for overall performance after CL. The performances of developed methods are compared with that of IL, strategy sharing (SS), and weighted SS (WSS). Obtained results show the superior performance of AOE-based methods as compared to that of existing CL methods, which do not use the notion of AOE. These results are very encouraging in support of the idea that "cooperation based on the AOE" performs better than the general CL methods. 相似文献
Security is one of the critical aspects of current systems, which are based on loosely coupled and technology-agnostic service-oriented architectures (SOA). Though SOA is the driving force for enterprises to open their ends for global business collaborations, nevertheless it evolves many challenges for modeling and enforcing security. One of the main problems for designing secure systems is the lack of consistent frameworks and methodologies for modeling security concerns. Traditional approaches consider security at the end of system development, which evolves inflexible and un-configurable systems, which are too difficult to maintain and manage. The other major problem with current approaches is that they assume pre-defined and hard-coded security patterns and mechanisms for secure system design. Whereas, the evolving SOA systems require configurable security to realize different security patterns and security policies in a variety of business scenarios. To solve these problems, it is necessary to model security concerns from the beginning of system modeling in a platform-independent way. This paper proposes a pattern refinement approach for security modeling to achieve configurable and declarative security, based on the principles of abstraction, refinement, separation-of-concerns and maintainability to achieve flexible configurations of SOA security. In the proposed approach, a Domain Expert defines abstract policies using common security vocabulary and a Security Expert models security with patterns and refines them for a target architecture in successive systematic refinements. Furthermore, it facilitates the transformation of abstract security models into executable security policies for the target platforms. 相似文献