Internet-based monitoring of distributed control systems-Anundergraduate experiment

This paper presents the development of an Internet-based system to allow monitoring of important process variables from a distributed control system (DCS). The system is formulated as an add-on to an undergraduate experiment on the development of a desktop DCS. This paper describes the hardware and software design considerations which enable the users to access the process variables on the DCS, remotely and effectively, using only a commonly available Web browser     

A dry-patterned Cu(Mg) alloy film as a gate electrode in a thin-film transistor liquid crystal display

The annealing of a Cu(4.5at.%Mg)/SiO₂/Si structure in ambient O₂ at 10 mtorr and 300–500°C allows for the out-diffusion of the Mg to the Cu surface, forming a thin MgO (15 nm) layer on the surface. The surface MgO layer was patterned and successfully served as a hard mask for the subsequent dry etching of the underlying Mg-depleted Cu films using an O₂ plasma and hexafluoroacetylacetone (H(hfac)) chemistry. The resultant MgO/Cu structure, with a taper slope of about 30°, shows the feasibility of dry etching of Cu(Mg) alloy films using a surface MgO mask scheme. A dry-etched Cu(4.5at.%Mg) gate a-Si:H thin-film transistor (TFT) has a field-effect mobility of 0.86 cm²/Vs, a subthreshold swing of 1.08 V/dec, and a threshold voltage of 5.7 V. A novel process for the dry etching of Cu(Mg) alloy films that eliminates the use of a hard mask, such as Ti, and results in a reduction in the process steps is reported for the first time in this work.     

Optimal Layout of Bridge Trusses by Genetic Algorithms

In this paper we present an approach to the layout and shape-optimization problem of bridge truss structures using genetic algorithms. The objective is to find an optimal layout design that will have minimum weight or material volume, subject to performance constraints related to member stresses, joint displacements, and member buckling. An automated two-stage optimization search process, which integrates structural analysis by finite-element method, genetic algorithms, and cognitive topology patterns (domain knowledge), is developed to solve the optimal problem. Two examples concerning bridge truss structure are investigated to demonstrate the effectiveness of the proposed method in solving these layout-optimization problems.     

Robust stability of discrete-time systems using delta operators

The robust stability of discrete-time systems formulated in terms of the delta (δ) operator is discussed. That is, given the nominal characteristic equation P(δ) of a discrete-time system, it is of interest to know how much the coefficients can be perturbed while preserving stability. A procedure to obtain the maximum intervals for a perturbed polynomial P(δ) to still be stable is presented     

The Singapore Government's �ole in national computerization efforts

This paper examines the role of the Singapore Government in Singapore's computerization efforts. In restructuring Singapore's economy and sharpening its competitive edge, information technology (IT) is singled out as one of the economic boosting engines whose dynamic, innovative role will change the economic and social fabric of society leading to a better quality of life for Singaporeans. The government and its agencies have deliberately intervened in the IT diffusion process through proactive IT policies, effective regulations and implementation. The national computerization plans, namely, the National IT Plan and the IT2000 Report, contain a set of IT strategic initiatives. Although the socioeconomic conditions and the cultural factors do have a significant influence on the IT diffusion process, an understanding of roles different institutions play and the various institutional policies will provide a better assessment of the impacts of IT on Singapore's information economy.     

A frequency aliasing approach to chaos-based cryptosystems

In this paper, a chaos-based cryptosystem using sampled chaos signals with frequency-domain aliasing is proposed. In this scheme, a higher degree of randomness of the running-key sequence is obtained, and an additional random seed consisting of the sampling frequency as the parameter is introduced. This leads to an enhancement of the cryptosystem security. Numerical and simulation results of a Lorenz cryptosystem are given to demonstrate the performance and effectiveness of the proposed approach.     

IT2000: A critical appraisal of Singapore's state-wide strategic planning process for information technology

In April 1992, the Singapore Government announced its information technology (IT) vision and plan for the next 15 years to turn Singapore into ‘an intelligent island’, providing a strategic regional switching centre for expertise, goods, services and information. At the heart of this plan is a national information infrastructure that would capitalize on information as a key factor of production and an important ingredient for enhancing the quality of life of its people. Code named ‘IT2000’, the plan was developed by 60 senior managers at the National Computer Board in 1991 with participation and inputs from about 200 business and industry leaders, domain experts and academics. This paper describes the background of Singapore's drive into the information age, the IT2000 planning process, the roles of various participants and the main recommendations of the plan. An evaluation of IT2000 is made in terms of its objectives, its unanticipated results and its impacts on industry participants. Implications and lessons are drawn for strategic IT planning at the national or sectoral level.     

A framework for integrating databases with knowledge bases for structural engineering

The focus of this paper is on the problem of how can we easily combine the advantages of database and knowledge-based systems. Solving this problem has the potential to radically extend the usefulness of existing database systems. Conversely, the solution would also make large-scale knowledge-based systems less costly to construct. In order to solve this problem, we present a framework for exploring the various alternatives in the integration of the two kinds of systems. We also use this framework to motivate our proposed solution: knowledge-embedded database systems. Our proposal entails the use of simple but powerful extensions of a database system to increase its ability to represent and manipulate knowledge. We describe Kbase, an environment for developing knowledge-embedded database systems. We further illustrate our proposed solution with IPDOS, a Kbase application for the preliminary design of offshore structures.     

Experimental results on preprocessing of path/cut terms in sim ofdisjoint products technique

Researchers have proposed cardinality-, lexicographic-, and Hamming-distance-order methods to preprocess the path terms in sum of disjoint products (SDP) techniques for network reliability analysis. For cutsets, an ordering based on the node partition associated with each cut is suggested. Experimental results showing the number of disjoint products and computer time involved in generating SDP terms are presented. Nineteen benchmark networks containing paths varying from 4 to 780, and cuts from 4 to 7376, are considered. Several SDP techniques are generalized into three propositions to find their inherent merits and drawbacks. An efficient SDP technique is then used to run input files of paths/cuts preprocesses using cardinality-, lexicographic-, and Hamming-distance-ordering, and their combinations. The results are analyzed, showing that preprocessing based on cardinality or its combinations with lexicographic-, and/or Hamming-distance-ordering performs better     

AN IMPROVED PROCEDURE FOR THE DETERMINATION OF HOT SPOT STRESSES IN TUBULAR JOINTS

Abstract— A conventional finite element method may show a weakness when determining the hot spot stress distributions in the brace/chord intersection region of offshore tubular joints. This is because the chosen element displacement functions do not implicitly satisfy the conditions which prevail on the free surfaces. A procedure has been proposed to modify the conventional finite element method so as to allow the hot spot stresses, which occur at the free boundary of the weld toe of tubular joints, to be determined with improved accuracy. The results obtained by this modified method are compared with both an experimental and a traditional finite element solution. The comparison shows that the modified solution is in better agreement with the experimental data as compared with the traditional solution.