Effect of support flexibility on the fundamental frequency of vibrating beams

The effect of rotational and translational support flexibility on the fundamental frequency of both an almost-clamped-clamped beam and a flexibly supported cantilever beam is considered. In each case the effect of a rotationally flexible support becomes more pronounced for decreasing values of the length-to-depth ratio. It is shown that the effect of end-fixity on the fundamental frequency can be of a magnitude equal to or greater than that due to the effect of shear deformation or rotatory inertia. Results using Bernoulli-Euler beam theory and Timoshenko beam theory are compared. Expressions are formulated that give the fundamental frequency as a function of the support flexibility, length to depth ratio and fundamental frequency for a rigid support.     

Simple inequalities in the vibrating string and heat conduction problems

Certain inequalities are presented, related to the L² norms of the solutions to the vibrating string and heat conduction partial differential equations; in particular, an “L² maximum principle” is derived for the heat equation, and similar inequalities for the vibrating string problem.     

A geometrical approach to problems of pursuit-evasion games

In this paper it is shown that a class of pursuit-evasion games can be treated more simply by the geometrical approach with the topological properties of the reachable region and by the method of functional analysis. Conditions for capture and optimal strategies are derived. A numerical example is given to show both the optimal open-loop strategies of players and the optimal trajectories of the game.     

Generalized procedure of the reduction method for vibrating problems of orthotropic plates

A reduction method is proposed for deriving an approximate formula for estimating the natural frequency of an orthotropic plate by using the results of an isotropic one. To justify the method, approximate formulae for estimating the natural frequency of clamped orthotropic rectangular and elliptical plates are derived from results previously reported for clamped isotropic rectangular and elliptical ones, respectively. The accuracy of the approximate formulae is discussed.     

An information-pattern-based approach to novelty detection

In this paper, a new novelty detection approach based on the identification of sentence level information patterns is proposed. First, “novelty” is redefined based on the proposed information patterns, and several different types of information patterns are given corresponding to different types of users’ information needs. Second, a thorough analysis of sentence level information patterns is elaborated using data from the TREC novelty tracks, including sentence lengths, named entities (NEs), and sentence level opinion patterns. Finally, a unified information-pattern-based approach to novelty detection (ip-BAND) is presented for both specific NE topics and more general topics. Experiments on novelty detection on data from the TREC 2002, 2003 and 2004 novelty tracks show that the proposed approach significantly improves the performance of novelty detection in terms of precision at top ranks. Future research directions are suggested.     

An Asian rally in Beijing to discuss energy problems

About 180 scientists and governmental officials from 11 Asian countries rallied in Beijing on February 21 and 22 to discuss issues concerning energy and the environment.     

一种自适应变步长迭代动态规划方法研究

针对传统迭代动态规划方法计算效率低的缺点,提出了一种改进的自适应变步长迭代动态规划方法,在求解中引人Runge—Kutta—Fehlberg自适应变步长方法来提高寻优精度和求解效率。以经典的间歇反应过程动态优化问题作为研究实例．研究结果表明：所提出的自适应变步长迭代动态规划方法,在保留传统的迭代动态规划方法有效寻找全局最优优点的同时,能够进一步提高寻优精度,而且优化效率也较高。     

An interdisciplinary and application-oriented approach to teach microfluidics

Microfluidics is a relatively novel interdisciplinary research area with broad applications in chemistry, physics, material science, and biology. Despite the rapid growth of the field, students'' exposure to microfluidic technologies is still limited and often insufficient to appreciate the advantages over other commonly used technologies. To this end, we designed a five-day course, “Microfluidics for microbial ecology,” in which students with very different backgrounds learn the basics of microfluidic technologies and sample a range of applications in microbial ecology. The course was created for Master and Ph.D. students interested in applying microfluidics to their research and, therefore, followed an application-oriented approach. The presentation of critical aspects of fluid flow phenomena at the microscale and an outline of the advantages and constraints of the technology provide students with the background to design and perform microfluidics-based experiments. In order to improve the effectiveness of learning in a class with diverse interests and backgrounds, two active learning exercises were implemented. The first comprised the design of an individualized microfluidics experiment in parallel with the lectures: students were guided to apply each module to their personalized application and discuss it in groups. The second was a group experimental activity, in which students jointly set up, performed, analyzed, and presented a microfluidics-based experiment. Given the multidisciplinary teaching context, the course was able to foster common conceptual ground and promote discussion among students. This application-oriented approach built upon experimental activities and in-class discussion is well suited to promote learning in a technology-related subject such as microfluidics.     

An integer programming approach to reference staff scheduling

We address the problem of scheduling the reference staff of a large academic library where available reference staffing and time flexibility are highly constrained. The problem is modeled as a multiple choice integer program and is solved using existing software. The computer model constructed a superior schedule to the current manual method and takes 1.2 seconds of computer time versus many hours by hand.     

A Compressive Privacy approach to Generalized Information Bottleneck and Privacy Funnel problems

This paper explores a Compressive Privacy (CP) methodology for optimal tradeoff between utility gain and privacy loss. CP represents a dimension-reduced subspace design of optimally desensitized query that may be safely shared with the public. Built upon the information and estimation theory, this paper proposes a “differential mutual information” (DMI) criterion to safeguard the privacy protection (PP). Algorithmically, DMI-optimal solutions can be derived via the Discriminant Component Analysis (DCA). Moreover, DCA has two machine learning variants (one in the original space and another is the kernel space) good for supervised learning applications. By extending the notion of DMI to the utility gain and privacy loss, CP unifies the conventional Information Bottleneck (IB) and Privacy Funnel (PF) and lead to two constrained optimizers, named Generalized Information Bottleneck (GIB) and Generalized Privacy Funnel (GPF). In the supervised learning environments, DCA can be further extended to a DUCA machine learning variant to reach an optimal tradeoff between utility gain and privacy loss. Finally, for fast convergence, a golden-section iterative method is developed particularly for solving the two constrained optimization problems: GIB and GPF.     

An efficient solution of hamiltonian boundary value problems by combined gauss pseudospectral method with differential continuation approach

Our paper deals with an effective application of the pseudospectral method to solution of Hamiltonian boundary value problems in optimal control theory. The developed numerical methodology is based on the celebrated Gauss pseudospectral approach. The last one makes it possible to reduce the conventional Hamiltonian boundary value problem to an auxiliary algebraic system. The implementable algorithm we propose is computationally consistent and moreover, involves numerically tractable results for a relative small discretization grids. However, the solution of the obtained algebraic equations system may has a low convergence radius. We next use the differential continuation approach in order to weaken the necessity of the well-defined initial conditions for the above algebraic system. The presented solution procedure can be extremely useful when the generic shooting-type methods fail because of sensitivity or stiffness. We discuss some numerical results and establish the efficiency of the proposed methodology.     

胎心监护在临床应用中常见问题分析及处理措施

胎心监护是监测胎儿宫内状况的检查之一,目的在于及时发现胎儿宫内缺氧,已越来越广泛应用于临床。临床应用中,胎监曲线图常常受多种因素的影响,导致假阳性率升高和胎儿宫内窘迫的过度诊断,增加过多的产科干预。文章分析了胎心监护在临床应用中存在的问题,探讨了提高胎心监护曲线准确性的临床技术要领,指出加强临床医师素质和技能培训的重要性,也就仪器的维护和管理提出了建议。     

CANSEARCH: An expert systems approach to document retrieval

This paper concerns the provision of a computerized intermediary system to facilitate online document retrieval from large-scale data bases directly by users of the retrieved information. The system does not require the user to be knowledgeable or undergo any training in the use of the underlying retrieval system. The scope for a novel intermediary system relating to recent developments in expert systems has been identified and a system entitled CANSEARCH designed to enable doctors to specify queries to retrieve cancer-therapy-related documents stored in the MEDLINE data base. The design of the intermediary system uses the principle of search space abstraction, employing menu selection from a touch terminal and encapsulating the necessary intermediary expertise using rule-based techniques programmed in PROLOG. CANSEARCH performed well enough to justify the approach taken, suggesting that further development of CANSEARCH and of intermediary systems for document retrieval in other subject areas should be undertaken.     

An economic modelling approach to information security risk management

This paper presents an approach enabling economic modelling of information security risk management in contemporaneous businesses and other organizations. In the world of permanent cyber attacks to ICT systems, risk management is becoming a crucial task for minimization of the potential risks that can endeavor their operation. The prevention of the heavy losses that may happen due to cyber attacks and other information system failures in an organization is usually associated with continuous investment in different security measures and purchase of data protection systems. With the rise of the potential risks the investment in security services and data protection is growing and is becoming a serious economic issue to many organizations and enterprises. This paper analyzes several approaches enabling assessment of the necessary investment in security technology from the economic point of view. The paper introduces methods for identification of the assets, the threats, the vulnerabilities of the ICT systems and proposes a procedure that enables selection of the optimal investment of the necessary security technology based on the quantification of the values of the protected systems. The possibility of using the approach for an external insurance based on the quantified risk analyses is also provided.     

A new approach to average consensus problems with multiple time-delays and jointly-connected topologies

This paper investigates average consensus problem in networks of continuous-time agents with delayed information and jointly-connected topologies. A lemma is derived by extending the Barbalat's Lemma to piecewise continuous functions, which provides a new analysis approach for switched systems. Then based on this lemma, a sufficient condition in terms of linear matrix inequalities (LMIs) is given for average consensus of the system by employing a Lyapunov approach, where the communication structures vary over time and the corresponding graphs may not be connected. Finally, simulation results are provided to demonstrate the effectiveness of our theoretical results.     

An embedding approach to the stability of some nonlinear discrete systems

An embedding approach is proposed to investigate the stability of some nonlinear sampled data systems. It is shown that the stability criterion so obtained may conclude for stability when other criteria do not apply. The approach could be extended in a more general way.