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《国家科学评论(英文版)》2015,(2)
Catalysis, as a key and enabling technology, plays an increasingly important role in ields ranging from energy, environment and agriculture to health care. Rational design and synthesis of highly eicient catalysts has become the ultimate goal of catalysis research. hanks to the rapid development of nanoscience and nanotechnology, and in particular a theoretical understanding of the tuning of electronic structure in nanoscale systems, this element of design is becoming possible via precise control of nanoparticles' composition, morphology, structure and electronic states. At the same time, it is important to develop tools for in situ characterization of nanocatalysts under realistic reaction conditions, and for monitoring the dynamics of catalysis with high spatial, temporal and energy resolution. In this review, we discuss coninement efects in nanocatalysis, a concept that our group has put forward and developed over several years. Taking the conined catalytic systems of carbon nanotubes, metal-conined nano-oxides and 2D layered nanocatalysts as examples, we summarize and analyze the fundamental concepts, the research methods and some of the key scientiic issues involved in nanocatalysis. Moreover, we present a perspective on the challenges and opportunities in future research on nanocatalysis from the aspects of:(1) controlled synthesis of nanocatalysts and rational design of catalytically active centers;(2) in situ characterization of nanocatalysts and dynamics of catalytic processes;(3) computational chemistry with a complexity approximating that of experiments; and (4) scale-up and commercialization of nanocatalysts. 相似文献
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电力电子设备谐波污染问题越来越严重,功率因数校正技术是解决该问题的最有效方法,而有源功率因数校正(APFC)技术因其独特的优势成了该领域的研究重点。文章介绍了功率因数的定义和有源功率因数校正技术原理,并根据当前的工业应用以及研究热点,对数字控制APFC技术进行分析研究,重点阐述了APFC技术的控制策略以及数字控制的实现方式。 相似文献
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资源系统工程的研究与应用 总被引：2，自引：1，他引：1
本文从资源定义出发,提出资源系统是指在一定区域内能够产生经济价值的、以提高人类当前和将来福利因素和条件的复杂系统。资源系统工程是对资源系统进行合理规划、设计和运行管理的一门交叉学科。研究分析认为：资源系统工程的理论基础是系统工程理论、系统工程技术和资源科学,研究的主要内容为资源系统规律、资源开发利用、资源协调控制,并初步确定了资源系统工程研究的方法论和学科体系。文章最后指出资源生态学、资源信息学的研究、资源系统定量分析,以及现代工程技术和方法的采用是资源系统工程研究的重点方向。资源系统工程是一门正在孕育发展中的学科,有待进一步去探索。 相似文献
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《Information processing & management》2023,60(2):103219
Misinformation threatens modern society by promoting distrust in science, changing narratives in public health, heightening social polarization, and disrupting democratic elections and financial markets, among a myriad of other societal harms. To address this, a growing cadre of professional fact-checkers and journalists provide high-quality investigations into purported facts. However, these largely manual efforts have struggled to match the enormous scale of the problem. In response, a growing body of Natural Language Processing (NLP) technologies have been proposed for more scalable fact-checking. Despite tremendous growth in such research, however, practical adoption of NLP technologies for fact-checking still remains in its infancy today.In this work, we review the capabilities and limitations of the current NLP technologies for fact-checking. Our particular focus is to further chart the design space for how these technologies can be harnessed and refined in order to better meet the needs of human fact-checkers. To do so, we review key aspects of NLP-based fact-checking: task formulation, dataset construction, modeling, and human-centered strategies, such as explainable models and human-in-the-loop approaches. Next, we review the efficacy of applying NLP-based fact-checking tools to assist human fact-checkers. We recommend that future research include collaboration with fact-checker stakeholders early on in NLP research, as well as incorporation of human-centered design practices in model development, in order to further guide technology development for human use and practical adoption. Finally, we advocate for more research on benchmark development supporting extrinsic evaluation of human-centered fact-checking technologies. 相似文献
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Various technology innovations and applications have been developed to fight the coronavirus pandemic. The pandemic also has implications for the design, development, and use of technologies. There is an urgent need for a greater understanding of what roles information systems and technology researchers can play in this global pandemic. This paper examines emerging technologies used to mitigate the threats of COVID-19 and relevant challenges related to technology design, development, and use. It also provides insights and suggestions into how information systems and technology scholars can help fight the COVID-19 pandemic. This paper helps promote future research and technology development to produce better solutions for tackling the COVID-19 pandemic and future pandemics. 相似文献
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Reducing the NOx emissions from Diesel engines remains as a challenging issue as the emission standards for Diesel engine powered vehicles have become more stringent than ever before. Urea-based selective catalytic reduction (SCR) systems have emerged as a promising technique in addressing this issue. However, the SCR performance in terms of NOx reduction and ammonia slip continues as an ongoing challenge due to the engine exhaust gas temperature variations, Diesel emission characteristics (especially high NO/NO2 ratio), and immature SCR controls. The purpose of this study is to improve the SCR performance by feeding the SCR system with exhaust gas having the desired NO/NO2 ratio. The proposed complete active NO/NO2 ratio control consists of a low-level adaptive NO/NO2 ratio controller and a high-level nonlinear soot mass controller. The low-level controller utilizes the pre-SCR catalysts such as Diesel oxidation catalyst (DOC) to convert part of NO into NO2, while the high-level controller was designed and coordinated with the low-level controller to avoid NO2 reduction through the Diesel particulate filter (DPF). Simulation and experimental results show that the proposed active NO/NO2 ratio control has the potentials of regulating the NO/NO2 ratio to the desired value and thus considerably improving the SCR performance. Simulation results also illustrate that the active NO/NO2 ratio control can enable the SCR system size reduction by a half without a significant sacrifice on the overall tailpipe emission control performance. Such an integrated aftertreatment system control can be instrumental in reducing the cost and improving the performance of SCR systems, especially in low-temperature operations. 相似文献
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George N. Arnovick 《Information processing & management》1978,14(6):369-380
A perspective is presented to bring into focus the state-of-the-art and development of methods and criteria which relate to the problem of design and performance evaluation of information systems. Two major aspects of design and evaluation are considered. These are the initiation, planning, development and testing of new information systems, to include modification of existing structures; and the appraisals and measurement of operational systems and their components. A taxonomy of information systems is presented in order to provide for a basis of organized evaluation of system performance. 相似文献
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Charles Aguiar Daniel Leite Daniel Pereira Goran Andonovski Igor Škrjanc 《Journal of The Franklin Institute》2021,358(2):1376-1402
Overhead cranes are widely used structures for lifting and conveying heavy loads. The development of feedback control systems for such equipment is important due to the large number of potential applications and advantages over manual operation concerning stability and robustness. This paper aims to represent the key nonlinear dynamics of crane systems by means of a state-space fuzzy model with compact rule-base structure. The fuzzy model is useful to assist the design of a fuzzy controller based on the concept of parallel compensation. A well-posed conservative linear-matrix-inequality (LMI) feasibility problem is formulated so that a solution guarantees closed-loop Lyapunov stability, bounded control inputs, quick positioning of the supporting cart, and suppression of load oscillations and collisions. The fuzzy controller is composed by rules with linear control laws derived from local state-space models. The controller warrants asymptotic convergence of the states. Due to the nonlinear nature of the fuzzy model and controller, Jacobian linearization is avoided. The proposed fuzzy control approach for cranes has shown to be more effective and robust than an optimal quadratic controller, and able to move cargo smoothly and safely to a destination. Particularly, constrained and smoother control inputs avoid actuator saturation, and tend to increase its lifetime. Laboratory experiments using the LMI fuzzy controller and actual data validates the approach for cranes in actual scenario. 相似文献
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This article examines one particular set of technologies arising from developments in human genetics, those aimed at improving the targeting, design and use of conventional small molecule drugs-pharmacogenetics. Much of the debate about the applications and consequences of pharmacogenetics has been highly speculative, since little or no working technology is yet on the market. This article provides a novel analysis of the development of pharmacogenetics, and the social and ethical issues it raises, based on the sociology of technological expectations. In particular, it outlines how two alternative visions for the development of the technology are being articulated and embedded in a range of heterogeneous discourses, artefacts, actor strategies and practices, including: competing scientific research agendas, experimental technologies, emerging industrial structures and new ethical discourses. Expectations of how pharmacogenetics might emerge in each of these arenas are actively shaping the trajectory of this nascent technology and its potential socio-economic consequences. 相似文献
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《普罗米修斯》2012,30(4):357-372
Virtually everywhere, there is governmental interest in developing and using science and technology as a tool for economic development and other public purposes. States within the United States look to advance vis-à-vis other states, just as nations seek to rise in competitiveness. What institutional mechanisms work? What research and other strategies are effective? The Georgia Research Alliance (GRA) represents an important model that appears successful. During the 1990s, key business executives, university presidents, and state government forged a research partnership - GRA. A non-profit entity, GRA played a catalytic role in getting state government, industry, and universities in a specific region to work in concert to hire scientific luminaries, attract federal research funds, and translate research into economic development. The dynamics of this catalytic entity are discussed using a life-cycle model of organizational development. 相似文献
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The organization of open data hackathons or digital innovation competitions is a significant opportunity for nascent entrepreneurs to collaborate with external partners, promote new ideas and extend their applications to a new start-up. Prior studies have not thoroughly compared the execution of different strategies in many hackathons or digital innovation competitions. They only focus on the actions that the organizers of a specific hackathon have implemented or the challenges they have faced. Thus, the purpose of this paper is to examine goals and design strategies that contribute to the successful execution of open data hackathons and innovation competitions. Six case studies of open data hackathons and innovation competitions held between 2014 and 2018 in Thessaloniki have been explored to understand the co-ordination between the multiple stakeholders of these events and improve the execution of open data hackathons and innovation competitions. The outcomes indicate that the most critical design strategy was the involvement of mentors in the event and the level of support provided to nascent entrepreneurs to accelerate their creativity, develop applications and launch their prototypes on the market. 相似文献
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数据在不同信息系统之间传递的集成方案是当前企业信息化研究的重点,同时也是突破企业信息孤岛的有效手段,因此如何有效使用集成技术控制数据的输入和输出成为企业是否能成功实施信息系统的关键指标。在以往研究的基础上,从技术角度出发提出把XML编程语言作为底层数据库实现信息集成的关键阀门,突破了仅从应用层实现的信息集成局限,为今后企业有效实施信息集成提供了方便、可行的技术支撑。 相似文献
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In this paper, we present the state of the art in the field of information retrieval that is relevant for understanding how to design information retrieval systems for children. We describe basic theories of human development to explain the specifics of young users, i.e., their cognitive skills, fine motor skills, knowledge, memory and emotional states in so far as they differ from those of adults. We derive the implications these differences have on the design of information retrieval systems for children. Furthermore, we summarize the main findings about children’s search behavior from multiple user studies. These findings are important to understand children’s information needs, their search strategies and usage of information retrieval systems. We also identify several weaknesses of previous user studies about children’s information-seeking behavior. Guided by the findings of these user studies, we describe challenges for the design of information retrieval systems for young users. We give an overview of algorithms and user interface concepts. We also describe existing information retrieval systems for children, in specific web search engines and digital libraries. We conclude with a discussion of open issues and directions for further research. The survey provided in this paper is important both for designers of information retrieval systems for young users as well as for researchers who start working in this field. 相似文献
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《Research Policy》2019,48(10):103832
There has been an increasing interest in science, technology and innovation policy studies in the topic of policy mixes. While earlier studies conceptualised policy mixes mainly in terms of combinations of instruments to support innovation, more recent literature extends the focus to how policy mixes can foster sustainability transitions. For this, broader policy mix conceptualisations have emerged which also include considerations of policy goals and policy strategies; policy mix characteristics such as consistency, coherence, credibility and comprehensiveness; as well as policy making and implementation processes. It is these broader conceptualisations of policy mixes which are the subject of the special issue introduced in this article. We aim at supporting the emergence of a new strand of interdisciplinary social science research on policy mixes which combines approaches, methods and insights from innovation and policy studies to further such broader policy mix research with a specific focus on fostering sustainability transitions. In this article we introduce this topic and present a bibliometric analysis of the literature on policy mixes in both fields as well as their emerging connections. We also introduce five major themes in the policy mix literature and summarise the contributions made by the articles in the special issue to these: methodological advances; policy making and implementation; actors and agency; evaluating policy mixes; and the co-evolution of policy mixes and socio-technical systems. We conclude by summarising key insights for policy making. 相似文献
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目前我国的大气污染形势非常严峻,短期内难以取得明显的治理效果。治理大气污染需要科研工作在基础研究、技术研发等方面提供强有力的支撑。尽管我国对相关的科研工作有多年的长期支持,但未按照长期稳定支持的思路进行设计,导致目前的科研产出成果难以满足治理大气污染的需求。建议借鉴国际经验,突破现有科研支持方式,在大气污染重点方向上建立长期稳定的财政投入机制,加大对重点优秀研发团队持续稳定的支持,建立绩效评估和调整机制,以服务于长期大气污染防治的科技需求。 相似文献
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当前，在信息资源管理领域，有关信息自动化处理方面的研究较多涌现，相关的实用系统也在开发实验。自动分类便是其中之一。本文结合基于VSM理论的实用行业自动分类系统的开发实现，对构建分类概念空间的思路、步骤及主要技术，包括权值确定、算法构思、正确性及效率评价等相关问题进行讨论。 相似文献
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基于战略的组织结构设计 总被引：4，自引：0，他引：4
美国著名学者钱德勒(A.D.Chandler)认为:战略决定结构,结构追随战略。表明了组织结构必须依据战略而设计。以往的组织结构设计旨在为企业提供一个堆满了各种结构形式的篮子,任凭企业去选择,没有提出形式设计或选择的标准,结果这些结构外衣穿在企业身上并不得体。组织结构设计并非一定要在众多的形式中进行选择,甚至也并非一定要有清晰确定的结构形式,只要符合战略要求,并依据战略所确定的组织结构倾向程度都可以作为企业的组织结构。 相似文献