Analysis and design of digital predictive controller for PFC Cuk converter

A digital predictive control strategy for Power Factor Correction (PFC) is presented in this paper. The duty cycles required to achieve unity power factor in one half line period are calculated in advance by using a predictive algorithm and implemented using low cost PIC Microcontroller. A single stage PFC circuit controlled by these pre-calculated duty cycles can achieve sinusoidal current waveform. The output voltage of PFC circuit is regulated by an outer PI controller. A low frequency, small signal model of the rectifier is developed in order to design a PI voltage controller. A prototype of front end AC–DC converter followed by DC–DC Cuk converter controlled by a PIC Microcontroller is developed. Both the simulation and experimental results reveal that the proposed digital predictive strategy provides low THD, high power factor and better performance due to its lower calculation requirement and simple implementation.     

Improvement of battery lifetime in software-defined network using particle swarm optimization based cluster-head gateway switch routing protocol with fuzzy rules

The software-defined network (SDN) is one of the network architectures, in which the data plane and control plane is divided from each other, and the network can be handled using a sensibly centralized controller and this method is adopted to reconfigure the wireless sensor network automatically. In this article, to implement the SDN in MANET, in which control nodes can be chosen in SDN dynamically for the activation of MANET function to allocate the works to other mobile nodes to the base station. However, in the field of mobile ad hoc networks, the network lifetime, and battery lifetime is one of the major problems and the energy consumption can play a significant rule for the transmission of data in the SDN. Therefore, in this article, particle swarm optimization (PSO) based CGSR (cluster-head gateway switch routing protocol) algorithm with fuzzy rules is proposed to increase the network lifetime of battery powered mobile nodes by reducing the energy consumptions of each node in software-defined MANET. In this proposed method, a routing method that can permit various mobile nodes with low battery power to transmits the data from source node to base station. We design a PSO based CGSR routing protocol by selecting the routing mobile nodes using fuzzy rules for packet transmission. In CGSR process, the formation of cluster and selection of cluster head is executed depending on the particle swarm optimization method. This proposed routing protocol can be used to enhance the battery lifetime by extension of the network lifetime with numerical analysis for efficient route node selection.     

HIPAA's Effect on Web Site Privacy Policies

Healthcare institutions typically post their privacy practices online as privacy policy documents. We conducted a longitudinal study that examines the effects of HIPAA's enactment on a collection of privacy policy documents for a fixed set of organizations over a four-year period. We present our analysis of 24 healthcare privacy policy documents from nine healthcare Web sites, analyzed using goal mining, a content-analysis method that supports extraction of useful information about institutions' privacy practices from documents. We compare our results to our pre-HIPAA study of these same institutions' online privacy practices and evaluate their evolution in the presence of privacy laws     

The effects of user factors and symbol referents on public symbol design using the stereotype production method

This study investigated the influence of user factors and symbol referents on public symbol design among older people, using the stereotype production method for collecting user ideas during the symbol design process. Thirty-one older adults were asked to draw images based on 28 public symbol referents and to indicate their familiarity with and ease with which they visualised each referent. Differences were found between the pictorial solutions generated by males and females. However, symbol design was not influenced by participants' education level, vividness of visual imagery, object imagery preference or spatial imagery preference. Both familiar and unfamiliar referents were illustrated pictorially without much difficulty by users. The more visual the referent, the less difficulty the users had in illustrating it. The findings of this study should aid the optimisation of the stereotype production method for user-involved symbol design.     

Fodor and Pylyshyn on connectionism

Fodor and Pylyshyn (1988) have argued that the cognitive architecture is not Connectionist. Their argument takes the following form: (1) the cognitive architecture is Classical; (2) Classicalism and Connectionism are incompatible; (3) therefore the cognitive architecture is not Connectionist. In this essay I argue that Fodor and Pylyshyn's defenses of (1) and (2) are inadequate. Their argument for (1), based on their claim that Classicalism best explains the systematicity of cognitive capacities, is an invalid instance of inference to the best explanation. And their argument for (2) turns out to be question-begging. The upshot is that, while Fodor and Pylyshyn have presented Connectionists with the important empirical challenge of explaining systematicity, they have failed to provide sufficient reason for inferring that the cognitive architecture is Classical and not Connectionist.     

Aerodynamic design via control theory

Conclusion The purpose of the last three sections is to demonstrate by representative examples that control theory can be used to formulate computationally feasible procedures for aerodynamic design. The cost of each iteration is of the same order as two flow solutions, since the adjoint equation is of comparable complexity to the flow equation, and the remaining auxiliary equations could be solved quite inexpensively. Provided, therefore, that one can afford the cost of a moderate number of flow solutions, procedures of this type can be used to derive improved designs. The approach is quite general, not limited to particular choices of the coordinate transformation or cost function, which might in fact contain measures of other criteria of performance such as lift and drag. For the sake of simplicity certain complicating factors, such as the need to include a special term in the mapping function to generate a corner at the trailing edge, have been suppressed from the present analysis. Also it remains to explore the numerical implementation of the design procedures proposed in this paper.     

Nucleation and growth of potassium dihydrogen phosphate crystals in silica gels

Kinetic studies on nucleation and growth of potassium dihydrogen phosphate crystals in silica gels show that the rate-determining process for the growth of these crystals in silica gels is diffusion. Morphology, microhardness and perfection of gel grown crystals are also reported.     

Book reviews

Electronic Finance Law Chris Reed, 1993 Hemel Hempstead: Woodhead‐Faulkner. 450 pp. £50.00

Introduction to Computer Law, 2nd Edn David I. Bainbridge, 1993 London: Pitman £18.99

Deontic Logic in Computer Science: normative system specification John‐Jules CH. Meyer & Roel J. Wieringa, 1993 London: John Wiley £34.95, xiv + 317pp.     

A modular and parameterized presentation of pregroup calculus

The concept of pregroup was introduced by Lambek for natural language analysis, with a close link to non-commutative linear logic. We reformulate the pregroup calculus so as to extend it by composition with other logics and calculi. The cut elimination property and the decidability property of the sequent calculus proposed in the article are shown. Properties of composed calculi are also discussed.     

The effects of incorporating a virtual agent in a computer-aided test designed for stress management education: The mediating role of enjoyment

Drawing upon the Entertainment–Education paradigm, this study evaluated the effectiveness of a computer-aided interactive test designed for stress management education targeting college students. The presence (vs. absence) of a virtual agent incorporated into the interactive test was proposed as the key factor that induces enjoyment and educational outcomes. The interactive test consisted of scenarios describing stressful situations that could occur in college students’ everyday lives. Furthermore, college students could relate the concerns raised by these hypothetical situations to the ways they manage their stress and mental health. After the student’s choice behavior in each scenario, a virtual agent conveyed health-related educational messages via a text-modal dialogue box. Participants who took the interactive test in which there was a virtual agent perceived the test as more educational and entertaining than those who took the test without a virtual agent. Results of a path analysis also revealed a significant mediating role of enjoyment on educational outcomes (i.e., students’ enjoyment of the interactive test mediated the effects of the presence of a virtual agent on their perceived educational value of health information), thus confirming the Entertainment–Education link. In addition, engaging in the interactive test resulted in stress management self-efficacy improvement. Theoretical and practical implications are discussed.