首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 31 毫秒
1.
The paper analyses the Italian contribution to the world scientific production, its relative citation impact, its international collaborations and scientific productivity compared with the most productive EU countries over the period 1980–2009. It shows that despite the fact that the level of funding has been dramatically low during the past decades, Italian science has been able to increase its performance up to 2007. Italian science is a “cathedral in the desert”. However, a recent reduction in the level of scientific production, the lagging behind in international scientific collaboration (highly correlated with the relative citation impact) and the great heterogeneity of researchers’ productivity (absence of correlation of number of researchers with quality and quantity of scientific production) may mark the start of a decline of Italian science. The paper concludes that the increased funding must go hand-in-hand with reform of autonomy and governance and calling for a sound system of internal quality control and performance enhancement.  相似文献   

2.
3.
Awareness has been extensively studied in human computer interaction (HCI) and computer supported cooperative work (CSCW). The success of many collaborative systems hinges on effectively supporting awareness of different collaborators, their actions, and the process of creating shared work products. As digital libraries are increasingly becoming more than just repositories for information search and retrieval – essentially fostering collaboration among its community of users – awareness remains an unexplored research area in this domain. We are investigating awareness mechanisms in CiteSeer, a scholarly digital library for the computer and information science domain. CiteSeer users can be notified of new publication events (e.g., publication of a paper that cites one of their papers) using feeds as notification systems. We present three cumulative user studies – requirements elicitation, prototype evaluation, and naturalistic study – in the context of supporting CiteSeer feeds. Our results indicate that users prefer feeds that place target items in query-relevant contexts, and that preferred context varies with type of publication event. We found that users integrated feeds as part of their broader, everyday activities and used them as planning tools to collaborate with others.  相似文献   

4.
This paper is concerned with control design for a generalized Takagi–Sugeno fuzzy system. The Takagi–Sugeno fuzzy system generally describes nonlinear systems by employing local linear system representations, while a generalized fuzzy system to be considered in this paper describes even a wider class of nonlinear systems by representing locally nonlinear systems. For such a generalized system, a stabilizing controller design method is proposed by introducing a new class of non-PDC controllers. A non-PDC controller is a generalized controller of PDC one, which is a traditional fuzzy controller. Stabilizing controller design conditions are given in terms of a set of linear matrix inequalities (LMIs), which are easily numerically solvable. A relaxation method is used to reduce the conservatism of design conditions. Finally, numerical examples are given to illustrate our nonlinear control design and to show the effectiveness over other existing results.  相似文献   

5.
The facet-analytic paradigm is probably the most distinct approach to knowledge organization within Library and Information Science, and in many ways it has dominated what has be termed “modern classification theory”. It was mainly developed by S.R. Ranganathan and the British Classification Research Group, but it is mostly based on principles of logical division developed more than two millennia ago. Colon Classification (CC) and Bliss 2 (BC2) are among the most important systems developed on this theoretical basis, but it has also influenced the development of other systems, such as the Dewey Decimal Classification (DDC) and is also applied in many websites. It still has a strong position in the field and it is the most explicit and “pure” theoretical approach to knowledge organization (KO) (but it is not by implication necessarily also the most important one). The strength of this approach is its logical principles and the way it provides structures in knowledge organization systems (KOS). The main weaknesses are (1) its lack of empirical basis and (2) its speculative ordering of knowledge without basis in the development or influence of theories and socio-historical studies. It seems to be based on the problematic assumption that relations between concepts are a priori and not established by the development of models, theories and laws.  相似文献   

6.
The transformation of many governments all around the world into new forms, namely, electronic government (e-Government), could not leave the Greek government unaffected. Therefore, it initiated an e-Government project related to national information systems and finance services, the Greek Taxation Information System (TAXIS). The purpose of this paper is to investigate the success of TAXIS from the perspective of expert employees, who work in public taxation agencies. This topic is interesting, because TAXIS is applied in a tax-driven country, under a mandatory setting. Also, it is the first time that the success of this project is examined, from the perspective of employees, using IS success models. The study adapts DeLone and McLean [DeLone, W. H., & McLean, E. R. (2003). The DeLone and McLean model of information systems success: A ten year update. Journal of Management Information Systems, 19(4), 9–30] and Seddon's [Seddon, P. B. (1997). A respecification and extension of the DeLone and McLean model of IS success. Information Systems Research, 8(3) 240–253] information systems success models. The model developed includes the constructs of information, system and service quality, perceived usefulness and user satisfaction. The results provide evidence that there are strong connections between the five success constructs. All hypothesized relationships are supported, except for the relationship between system quality and user satisfaction. The empirical evidence and discussion presented can help the Greek Government improve and fully exploit the potential of TAXIS as an innovative tool for taxation purposes.  相似文献   

7.
The thesis of this study is to propose an extended methodology for laboratory based Information Retrieval evaluation under incomplete relevance assessments. This new methodology aims to identify potential uncertainty during system comparison that may result from incompleteness. The adoption of this methodology is advantageous, because the detection of epistemic uncertainty – the amount of knowledge (or ignorance) we have about the estimate of a system’s performance – during the evaluation process can guide and direct researchers when evaluating new systems over existing and future test collections. Across a series of experiments we demonstrate how this methodology can lead towards a finer grained analysis of systems. In particular, we show through experimentation how the current practice in Information Retrieval evaluation of using a measurement depth larger than the pooling depth increases uncertainty during system comparison.  相似文献   

8.
This paper presents a new stability analysis of networked control systems (NCSs) with network-induced delay and packet dropout. A novel augmented Lyapunov–Krasovskii functional (LKF) is constructed, which takes into account the feature of the sawtooth delay induced by sample-and-hold. Based on an improved version of Wirtinger's inequality and the convex combination method, a delay-dependent stability criterion is derived in terms of linear matrix inequalities (LMIs). The advantage of the proposed criterion lies in its simplicity and less conservativeness than some of the existing results. The new criterion is applied to the network-based state feedback control problems. Numerical examples are given to verify the effectiveness of the proposed criterion.  相似文献   

9.
This paper is about how institutions adapt and change to accommodate new technologies. Specifically it looks at how one set of institutions, the British Research Councils, accommodated to the emergence of biotechnology in the 1980s, charting the vicissitudes of their relationship and in particular the bitter quarrel which broke out between the Medical Research Council (MRC) and the Science and Engineering Research Council (SERC). It suggests that the key factor behind the conflict was not remit (i.e. defence of research territory) but differences in culture, with a lack of symmetry between the scientific paradigm which dominated the MRC's approach and the technological paradigm which drove the SERC's Biotechnology Directorate. Given this difference in cultures, it argues that some plurality of approach was inevitable and that attempts to impose a strong element of co-ordination would not have prevented conflict. However, lighter coordination might have helped, and this could in fact have been achieved had the British government at that time not abdicated from all leadership roles in relation to new technologies and provided no resources to help oil the wheels of change.  相似文献   

10.
The use of outcome control modes of research evaluation exercises is ever more frequent. They are conceived as tools to stimulate increased levels of research productivity, and to guide choices in allocating components of government research budgets for publicly funded institutions. There are several contributions in the literature that compare the different methodological approaches that policy makers could adopt for these exercises, however the comparisons are limited to only a few disciplines. This work, examining the case of the whole of the “hard sciences” of the Italian academic system, makes a comparison between results obtained from peer review type of evaluations (as adopted by the Ministry of Universities and Research) and those possible from a bibliometric approach (as developed by the authors). The aim is to understand to what extent bibliometric methodology, which is noted as relatively inexpensive, time-saving and exhaustive, can complement and integrate peer review methodology in research evaluation.  相似文献   

11.
This paper deals with the problem of stabilization by state feedback control of Takagi–Sugeno (T–S) fuzzy discrete-time systems with multiple fixed delays while imposing positivity in closed-loop. The obtained results are presented under linear programming (LP) form. In particular, the synthesis of state feedback controllers is first solved in terms of Linear programming for the unbounded controls case. This result is then extended to the stabilization problem by nonnegative controls, and stabilization by bounded controls. The stabilization conditions are derived using the single Lyapunov–Krasovskii functional (LKF). An example of a real plant is studied to show the advantages of the design procedure. A comparison between linear programming and LMI approaches is presented.  相似文献   

12.
The communication systems and disk or tape memory can sometimes cause clusters of errors, namely burst errors. There have been many designs in order to detect and even correct such errors. Recently, a new class of codes called m-spotty byte error correcting codes has found applications in high speed memory systems that employ random access memory chips wide Input/Output data, especially at 8, 16, or 32 bits. The MacWilliams identity provides the relationship between the weight distribution of a code and that of its dual code. Also, an interesting new metric called Rosenbloom–Tsfasman metric has been studied as an alternative metric for linear codes recently. In this paper, we combine these two interesting topics and introduce the m-spotty Rosenbloom–Tsfasman weights and the m-spotty Rosenbloom–Tsfasman weight enumerator of a binary code. Moreover, we prove a MacWilliams identity for the m-spotty Rosenbloom–Tsfasman weight enumerators.  相似文献   

13.
The financial and innovation literature generally claims that venture capital (VC) investments spur the growth of new technology-based firms (NTBFs). However, it has proved difficult so far to separate the “treatment” effect of the VC investment from the “selection” effect attributable to the ability of the VC investor to screen high growth NTBFs. The aim of this work is to test whether VC investments have a positive treatment effect on the growth of employment and sales of NTBFs. For this purpose we consider a 10-year longitudinal data set for 538 Italian NTBFs, most of which are privately held. The sample includes both VC-backed and non-VC-backed firms. We estimate Gibrat-law-type dynamic panel-data models augmented with time-varying variables that capture the VC status of firms. To control for the endogeneity of VC investments we use several GMM estimators. The econometric results strongly support the view that VC investments positively influence firm growth. The treatment effect of VC investments is of large economic magnitude, especially on growth of employment. Most of it is obtained immediately after the first round of VC finance. Conversely, the selection effect of VC appears to be negligible in the Italian context.  相似文献   

14.
The aim of this paper is to propose an explanation of the changes of dynamic matching between systemic properties of local production systems (LPS) and characteristics of the competitive environment. An evolutionary sequence travelled during the last three decades by Italian LPS is identified and an explanation of long-term dynamics is based on how information flows and knowledge are structured within a local environment. The “traditional” pattern of interlocking behaviours of different agents is defined as cognitive architecture, which evolutionarily emerges as invisible mind. Evolutionary pressures lead new patterns of relationships and interlocking behaviours, which we define as a tendency for more visible “minds” to assert themselves.  相似文献   

15.
多药马兜钤亚属是马兜铃属目前已知3个亚属中最小的一个亚属,约9种,其中8种产于热带 非洲,1种产于热带亚洲(马来西亚)。  本工作从经典分类学角度对该亚属的系统进行了探讨,首次利用花药数目及其排列方式将其划分为三个组,并对其中所含的种类进行了分类学处理,本文承认9种及3个新异名。  相似文献   

16.
In this paper, we describe an operational methodology for characterizing the architecture of complex technical systems and demonstrate its application to a large sample of software releases. Our methodology is based upon directed network graphs, which allows us to identify all of the direct and indirect linkages between the components in a system. We use this approach to define three fundamental architectural patterns, which we label core–periphery, multi-core, and hierarchical. Applying our methodology to a sample of 1286 software releases from 17 applications, we find that the majority of releases possess a “core–periphery” structure. This architecture is characterized by a single dominant cyclic group of components (the “Core”) that is large relative to the system as a whole as well as to other cyclic groups in the system. We show that the size of the Core varies widely, even for systems that perform the same function. These differences appear to be associated with different models of development – open, distributed organizations develop systems with smaller Cores, while closed, co-located organizations develop systems with larger Cores. Our findings establish some “stylized facts” about the fine-grained structure of large, real-world technical systems, serving as a point of departure for future empirical work.  相似文献   

17.
18.
The article analyzes user–IR system interaction from the broad, socio-cognitive perspective of lessons we can learn about human brain evolution when we compare the Neanderthal brain to the human brain before and after a small human brain mutation is hypothesized to have occurred 35,000–75,000 years ago. The enhanced working memory mutation enabled modern humans (i) to decode unfamiliar environmental stimuli with greater focusing power on adaptive solutions to environmental changes and problems, and (ii) to encode environmental stimuli in more efficient, generative knowledge structures. A sociological theory of these evolving, more efficient encoding knowledge structures is given. These new knowledge structures instilled in humans not only the ability to adapt to and survive novelty and/or changing conditions in the environment, but they also instilled an imperative to do so. Present day IR systems ignore the encoding imperative in their design framework. To correct for this lacuna, we propose the evolutionary-based socio-cognitive framework model for designing interactive IR systems. A case study is given to illustrate the functioning of the model.  相似文献   

19.
This paper presents a robust quasi-min–max model predictive control algorithm for a class of nonlinear systems described by linear parameter varying (LPV) systems subject to input constraints and unknown but bounded disturbances. The proposed control algorithm solves a semi-definite programming problem that explicitly incorporates a finite horizon cost function and linear matrix inequalities (LMI) constraints. For the purpose of the recursive feasibility of the optimization, the dual-mode approach is implied. Input-to-state stability (ISS) and quasi-min–max MPC are combined to achieve the closed-loop ISS of the controller with respect to the disturbance in LMI paradigm. Two examples of continuous stirred tank reactor (CSTR) and couple-mass-spring system are used to demonstrate the effectiveness of the proposed results.  相似文献   

20.
This paper is concerned with the problem of delay-dependent stability for a class of singular time-delay systems. By representing the singular system as a neutral form, using an augmented Lyapunov–Krasovskii functional and the Wirtinger-based integral inequality method, we obtain a new stability criterion in terms of a linear matrix inequality (LMI). The criterion is applicable for the stability test of both singular time-delay systems and neutral systems with constant time delays. Illustrative examples show the effectiveness and merits of the method.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号