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排序方式: 共有598条查询结果,搜索用时 15 毫秒
1.
The application of online analytical processing (OLAP) technology to bibliographic databases is addressed. We show that OLAP
tools can be used by librarians for periodic and ad hoc reporting, quality assurance, and data integrity checking, as well
as by research policy makers for monitoring the development of science and evaluating or comparing disciplines, fields or
research groups. It is argued that traditional relational database management systems, used mainly for day-to-day data storage
and transactional processing, are not appropriate for performing such tasks on a regular basis. For the purpose, a fully functional
OLAP solution has been implemented on Biomedicina Slovenica, a Slovenian national bibliographic database. We demonstrate the system's usefulness by extracting data for studying a selection
of scientometric issues: changes in the number of published papers, citations and pure citations over time, their dependence
on the number of co-operating authors and on the number of organisations the authors are affiliated to, and time-patterns
of citations. Hardware, software and feasibility considerations are discussed and the phases of the process of developing
bibliographic OLAP applications are outlined.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
2.
Bronisław Jańczuk Tomasz Białopiotrowicz Emil Chibowski Andrzej Dawidowicz Anna Kliszcz 《Journal of Materials Science》1990,25(3):1682-1685
The contact angles of water drops and diiodomethane drops on pellets made of controlled porosity glasses have been measured. The surface of the glasses was modified by thermal treatment at 873 K which led to an increase in the surface concentration of boron atoms. Glass modified with Carbowax 20M (polyethylene glycol) and fully hydroxylated glass have also been studied. Using the measured contact angles and modified Young equation, the dispersion and nondispersion components of the glass surface free energy have been calculated. The values show that with increasing heating time (increasing surface density of boron atoms) an increase in the surface polarity takes place. However, the polarity of the same samples decreases after treatment with Carbowax, increasingly so with higher boron atom concentrations. 相似文献
3.
A study of the behavior of current limiting fuses and of their effectiveness in protecting power thyristors is presented. Mathematical models simulating the prearcing and arcing characteristics of the fuse are described and used for analog computer evaluations. The junction temperature response of a thyristor to surge currents is analyzed with the aid of a further model. Finally, the fuse and thyristor simulations are coupled for a survey of the combined system. From this, a practical fuse/thyristor coordination rule is developed. 相似文献
4.
Alberto Schaeffer-Filho Emil Lupu Morris Sloman 《Journal of Network and Systems Management》2015,23(3):753-793
Ubiquitous systems and applications involve interactions between multiple autonomous entities—for example, robots in a mobile ad-hoc network collaborating to achieve a goal, communications between teams of emergency workers involved in disaster relief operations or interactions between patients’ and healthcare workers’ mobile devices. We have previously proposed the Self-Managed Cell (SMC) as an architectural pattern for managing autonomous ubiquitous systems that comprise both hardware and software components and that implement policy-based adaptation strategies. We have also shown how basic management interactions between autonomous SMCs can be realised through exchanges of notifications and policies, to effectively program management and context-aware adaptations. We present here how autonomous SMCs can be composed and federated into complex structures through the systematic composition of interaction patterns. By composing simpler abstractions as building blocks of more complex interactions it is possible to leverage commonalities across the structural, control and communication views to manage a broad variety of composite autonomous systems including peer-to-peer collaborations, federations and aggregations with varying degrees of devolution of control. Although the approach is more broadly applicable, we focus on systems where declarative policies are used to specify adaptation and on context-aware ubiquitous systems that present some degree of autonomy in the physical world, such as body sensor networks and autonomous vehicles. Finally, we present a formalisation of our model that allows a rigorous verification of the properties satisfied by the SMC interactions before policies are deployed in physical devices. 相似文献
5.
Mesh parameterization is one of the fundamental operations in computer graphics (CG) and computeraided design (CAD). In this paper, we propose a novel local/global parameterization approach, ARAP++, for singleand multi-boundary triangular meshes. It is an extension of the as-rigid-as-possible (ARAP) approach, which stitches together 1-ring patches instead of individual triangles. To optimize the spring energy, we introduce a linear iterative scheme which employs convex combination weights and a fitting Jacobian matrix corresponding to a prescribed family of transformations. Our algorithm is simple, efficient, and robust. The geometric properties (angle and area) of the original model can also be preserved by appropriately prescribing the singular values of the fitting matrix. To reduce the area and stretch distortions for high-curvature models, a stretch operator is introduced. Numerical results demonstrate that ARAP++ outperforms several state-of-the-art methods in terms of controlling the distortions of angle, area, and stretch. Furthermore, it achieves a better visualization performance for several applications, such as texture mapping and surface remeshing. 相似文献
6.
Robust‐Adaptive Control Strategies for a Time Delay Bioelectrochemical Process Using Interval Observers 下载免费PDF全文
The paper addresses the design and the analysis of adaptive and robust‐adaptive control strategies for a complex recycled wastewater treatment bioprocess. The design procedures are developed under the realistic assumptions that the bacterial growth rates are unknown and the influent flow rates are time‐varying and uncertain, but some lower and upper bounds of these uncertainties are known. The proposed control structures are achieved by combining a linearizing control law with an appropriately (asymptotic or interval based) state observer and with a parameter estimator used for on‐line estimation of unknown kinetics. These approaches are applied to a complex time delay bioprocess resulting from the association of a recycling bioreactor with an electrochemical reactor. Numerical simulations are performed in order to validate the proposed algorithms. 相似文献
7.
The high-resolution X-ray structures of the deoxy forms of four recombinant hemoglobins in which Trp37(C3)beta is replaced with Tyr (betaW37Y), Ala (betaW37A), Glu (betaW37E), or Gly (betaW37G) have been refined and analyzed with superposition methods that partition mutation-induced perturbations into quaternary structure changes and tertiary structure changes. In addition, a new cross-validation statistic that is sensitive to local changes in structure (a "local Rfree" parameter) was used as an objective measure of the significance of the tertiary structure changes. No significant mutation-induced changes in tertiary structure are detected at the mutation site itself for any of the four mutants studied. Instead, disruption of the intersubunit contacts associated with Trp37(C3)beta results in (1) a change in quaternary structure at the alpha1beta2 interface, (2) alpha subunit tertiary structure changes that are centered at Asp94(G1)alpha-Pro95(G2)alpha, (3) beta subunit tertiary structure changes that are located between residues Asp99(G1)beta and Asn102(G4)beta, (4) increased mobility of the alpha subunit COOH-terminal dipeptide, and (5) shortening of the Fe-Nepsilon2His(F8) bond in the alpha and beta subunits of the betaW37G and betaW37E mutants. In each case, the magnitude of the change in a particular structural parameter increases in the order betaW37Y < betaW37A < betaW37E approximately betaW37G, which corresponds closely to the degree of functional disruption documented in the preceding papers. 相似文献
8.
This paper constructs multirate linear multistep time discretizations based on Adams-Bashforth methods. These methods are
aimed at solving conservation laws and allow different timesteps to be used in different parts of the spatial domain. The
proposed family of discretizations is second order accurate in time and has conservation and linear and nonlinear stability
properties under local CFL conditions. Multirate timestepping avoids the necessity to take small global timesteps—restricted
by the largest value of the Courant number on the grid—and therefore results in more efficient computations. Numerical results
obtained for the advection and Burgers’ equations confirm the theoretical findings.
This work was supported by the National Science Foundation through award NSF CCF-0515170. 相似文献
9.
Leonidas Lymberopoulos Emil Lupu Morris Sloman 《Journal of Network and Systems Management》2003,11(3):277-303
This paper presents a framework for specifying policies for the management of network services. Although policy-based management has been the subject of considerable research, proposed solutions are often restricted to condition-action rules, where conditions are matched against incoming traffic flows. This results in static policy configurations where manual intervention is required to cater for configuration changes and to enable policy deployment. The framework presented in this paper supports automated policy deployment and flexible event triggers to permit dynamic policy configuration. While current research focuses mostly on rules for low-level device configuration, significant challenges remain to be addressed in order to:a) provide policy specification and adaptation across different abstraction layers; and, b) provide tools and services for the engineering of policy-driven systems. In particular, this paper focuses on solutions for dynamic adaptation of policies in response to changes within the managed environment. Policy adaptation includes both dynamically changing policy parameters and reconfiguring the policy objects. Access control for network services is also discussed. 相似文献
10.
S?ren?Emil?S?rensenEmail author Michael?R.?Hansen Morten?K.?Ebbesen Ole??.?Mouritsen 《Structural and Multidisciplinary Optimization》2012,45(6):907-916
Poor dynamics owing to polygon action is a known concern in mechanical applications of closed articulated chains. In this
paper a kinematic model of the polygon action in large chains of loop-sorting-systems is proposed. Through optimization techniques
the chain dynamics is improved by minimizing the polygon action using a parametric model of the track layout as design variables.
Three formulations of the kinematic polygon action are tested on an average sized planer tracks layout to find a superior
model. Verification of the proposed optimization method is performed using a state-of-the-art multi-body simulation model
of the chain dynamics. 相似文献