The design of an RF monolithic CMOS down‐converter

Abstract

The circuitry was constructed by standard commercial 0.35 μm CMOS fabrication processes and consists of a low noise amplifier (LNA) and a low voltage mixer that down‐converts S band RF signals into the IF band. The LNA is designed with the consideration of non‐quasi‐static channel resistance to accomplish the input matching both for gain and noise. A single‐ended Gilbert cell mixer is designed with LC tanks in order to achieve a low voltage scheme. Then the inter‐stage matching between the LNA and the mixer was accomplished by using a single integrated capacitor to save chip area.     

The design and implementation of an interactive news‐on‐demand system

Abstract

In this paper, we present a news‐on‐demand system that consists of 1) a news database, 2) a news search engine, and 3) a news editor. All multimedia data are stored in the news database. Through the system, readers not only can browse multimedia news in the database, but also can query the relevant news with a specified predicate. Also, to help journalists to edit their electronic news, we also design the news editor. It helps journalists to edit their news homepages, even if they are not experts in HTML programming.     

The relationship between the eigenstructures and trajectory sensitivity of autonomous linear time‐invariant systems

Abstract

In this paper we examine the relationship between the state trajectory deviation caused by system parameter variation and the normality of the system matrix for autonomous linear time‐invariant systems. Starting from two rational definitions of the state trajectory deviation, we derive upper bounds for the state trajectory deviation. All the results developed indicate that the normality of the system matrix is the dominant factor in the trajectory sensitivity to the system parameter variation.     

The design of a multi‐speed PSK modem

Abstract

Charge‐temperature, modified from bias‐temperature, technique is presented for the investigation of the interface properties of Al‐SiO₂‐Si (P) MOS capacitors. By using this technique, the change of interface trap states was found to be related to the treatment of charge‐temperature agin gand consequently the distribution of the mobile charges inside the oxide. An equivalent equation is expressed for the evaluation of interface trap states from the measured C‐V data. In addition, a two‐region model describing the distributions of the mobile charges of the capacitor after various charge‐temperature agings is proposed for the experimental observations. And the fitting results indicate that the effective Debye length due to interface trap states is about 20 Å.     

An application of experimental design‐an improvement of a golden mill

Abstract

The seismic behavior of lifeline systems is predominately controlled by the ground displacement/strain characteristics. This study investigates the wave propagation effect and the ground displacements and ground strains from the latest strong‐motion array data recorded at the Public Work Research Institute (PWRI) of Japan by using finite element method. Usually, the buried pipeline almost moves with the surrounding soil during seismic shaking. In this respect, the investigation of ground displacement characteristics can be used for further application to seismic design of buried pipelines.     

The hardware design of a speaker‐independent speech recognizer

Abstract

This paper presents a hardware approach to the realization of a speaker‐independent speech recognizer. This hardware includes a feature normalizer, a vector quantizer, and a hidden Markov model (HMM) scoring processor. It can meet real time requirements in moderate vocabulary applications. The finite‐register‐length effect is investigated so that the register length for representing the model parameters and the computation results can be determined. An error analysis for the HMM scoring procedure is also derived.     

Identification of continuous‐time delayed systems using an input pulse of arbitrary shape

Abstract

This article resolves difficulties of continuous identification often encountered in field testing, such as unsteady initial states, unknown disturbances, and noise‐corrupted measurements. The unique feature of the proposed method is that it divides the identification problem into two simpler estimation problems based on pulse testing of arbitrary shape. Sequential algorithms are developed to deal with the first estimation problem subjected to the zero portion of the input and then to solve the remaining problem subjected to the arbitrary portion of the input. The method provides a convenient way to fit model predictions to output measurements in the face of unknown initial states and static disturbances. Simulation results demonstrate that the use of the integral filter renders the method rather robust with respect to noise and model structure mismatch.     

The impact of the cost of quality on serial supply‐chain network design

This paper presents a model for supply‐chain design that considers the Cost of Quality as well as the traditional manufacturing and distribution costs (SC‐COQ model). It includes three main contributions: (1) the SC‐COQ model internally computes quality costs for the whole supply chain considering the interdependencies among business entities, whereas previous works have assumed exogenously given Cost of Quality functions; (2) the SC‐COQ model can be used at a strategic planning level to design a logistic route that achieves a maximum profit while considering the overall quality level within a supply chain; and (3) we provide two solution methods based on simulated annealing and a genetic algorithm and perform computational experiments on test instances.     

Transformation of continuous‐time state equations to discrete‐time state equations

Abstract

A method is proposed for transforming a continuous‐time state equation, x(t)=Ax(t)+Bu(t), to a discrete‐time state equation, x[(k+1)τ]=ø(τ)x(kτ)+B(τ)u(kτ). It is based on expanding the matrix exponential exp (Aτ) into a shifted matrix Chebyshev series. An example is given to demonstrate the superiority of the method over other methods.     

The effects of silica content,sintering temperature and sintering time on a Ni‐Zn ferrite

Abstract

In this experiment the effects of silica content, sintering time, and sintering temperature on the microstructure and magnetic properties of a ferrite, Ni₀₃₂Zn₀₆₈Fe₂O₄, were studied.

The initial permeability is reduced only slightly when the silica content is less than 0.2 wt %. The Q value is proportional to the silica content approximately. The peak value of μ _iQ product is about constant when the silica content is less than 0.2 wt %.

The best sintering temperature is between 1175°C and 1200°C. The addition of silica (<0.2 wt%) enhances the rate of densification, but the control of sintering time has to be more precise because the addition of silica makes the shape of μ _iQ product peak become sharper and narrower.     

Wind‐resistant design of high mast structures

Abstract

Today, a large number of High Mast Structures (HMS) is being constructed around the world. Usually, the structural systems are presented as monotubular towers or masts with a mass at the tip which has utility equipment mounted. The monotubular configuration of an HMS has a large ratio of height to horizontal dimension. This means that the HMS is not only very slender, but also more wind‐sensitive than any other common structures. Since failures of masts and monotubular towers or poles have occurred often, this confirms the necessity for a better understanding of wind‐excited behaviour on the HMS, and also a better design for a wind‐resistant HMS. This paper illustrates the basic theories of behaviors of along‐wind response, and across‐wind response. Prior to the present, design codes for HMSes have not been standardized. Therefore, this study has aimed to develop a suitable criterion of Wind Resistant Design (WRD) for HMS. We wish to produce guidelines to be used when designing a wind‐resistant HMS to counter wind‐excited responses. This paper starts with a theoretical approach. Computational Fluid Dynamics (CFD) and Finite Element Method (FEM) are reviewed and applied to the analytical development of the design criteria. Then, the design criteria and the procedure of WRD are established. And finally, a case study is presented for illustration. There are three major findings in this study. First, the results of the analysis of CFD show that when the polygon sides are more than 16, the total drag coefficient tends to the constant, which closes to leeward drag coefficient, and the windward coefficient tends to be zero. Second, it's recommended that an HMS had better adopt a gust effect factor, G, equal to 2.33 due to flexibility by geometric configuration and structural properties. Third, the total maximum response limitation of an HMS should be considered in across‐wind analysis for WRD procedures.     

A real‐time feature extraction method for PVC detection in bedside monitor

Abstract

This paper describes a fast and very efficient feature extraction method for discrimination of QRS and Premature Ventricular Contraction (PVC) beats in a microprocessor‐based bedside monitoring system. It converts each QRS and PVC beat into a positive‐pulse waveform by signal preprocessing. Two characteristic factors, the positive‐pulse and the pulse duration, are calculated when the onset and end points of each pulse have been detected by threshold detection. The prominent feature is extracted from a product of these two factors. This algorithm has been examined using 40 different patients’ electrocardiograph (ECG). The accuracy of QRS detection was 99.3 percent in the tests performed. The identification sensitivity of PVC was 81.2 percent with 18‐ different arrhythmia patients.     

Stability and robustness of time‐delay systems

Abstract

Using some properties of matrix measures and matrix's spectral radius, a new stability criterion for a linear time‐delay system is derived. This result is also extended to interval time‐delay systems.     

Space–time computational analysis of bio-inspired flapping-wing aerodynamics of a micro aerial vehicle

We present a detailed computational analysis of bio-inspired flapping-wing aerodynamics of a micro aerial vehicle (MAV). The computational techniques used include the Deforming-Spatial-Domain/Stabilized Space?CTime (DSD/SST) formulation, which serves as the core computational technique. The DSD/SST formulation is a moving-mesh technique, and in the computations reported here we use the space?Ctime version of the residual-based variational multiscale (VMS) method, which is called ??DSD/ SST-VMST.?? The motion and deformation of the wings are based on data extracted from the high-speed, multi-camera video recordings of a locust in a wind tunnel. A set of special space?Ctime techniques are also used in the computations in conjunction with the DSD/SST method. The special techniques are based on using, in the space?Ctime flow computations, NURBS basis functions for the temporal representation of the motion and deformation of the wings and for the mesh moving and remeshing. The computational analysis starts with the computation of the base case, and includes computations with increased temporal and spatial resolutions compared to the base case. In increasing the temporal resolution, we separately test increasing the temporal order, the number of temporal subdivisions, and the frequency of remeshing. In terms of the spatial resolution, we separately test increasing the wing-mesh refinement in the normal and tangential directions and changing the way node connectivities are handled at the wingtips. The computational analysis also includes using different combinations of wing configurations for the MAV and investigating the beneficial and disruptive interactions between the wings and the role of wing camber and twist.     

Displacement bound of beam‐column with time‐dependent boundary constraints

Abstract

A simplified explicit formula for the displacement bounds of the beam‐column subjected to time‐dependent boundary constraints is proposed. The formula is derived by means of removing time dependence from the boundary conditions. The proposed bounds provide a quick estimation of the displacements for problems with complex loading conditions.     

Development of machine learning‐based real time scheduling systems: using ensemble based on wrapper feature selection approach

There are two items that significantly enhance the generalisation ability (i.e. classification accuracy) of machine learning‐based classifiers: feature selection (including parameter optimisation) and an ensemble of the classifiers. Accordingly, the objective in this study is to develop an ensemble of classifiers based on a genetic algorithm (GA) wrapper feature selection approach for real time scheduling (RTS). The proposed approach can better enhance the generalisation ability of the RTS knowledge base (i.e. classifier) in comparison with three classical machine learning‐based classifier RTS systems, including the GA‐based wrapper feature selection mechanism, in terms of the prediction accuracy of 10‐fold cross validation as measured according to all the performance criteria. The proposed ensemble classifier RTS also provides better system performance than the three machine learning‐based RTS systems, including the GA‐based wrapper feature selection mechanism and heuristic dispatching rules, under all the performance criteria, over a long period in a flexible manufacturing system (FMS) case study.     

On the design theory of constant‐area‐mixing type jet compressors

Abstract

An analytical model for supersonic air ejector and the basic theory of ejector have been reviewed and used to obtain the performance characteristics of nozzles with different area ratios. The complete performance curve has been established. The entrainment ratio equation has been varified by experiments. In conjunction with an experimentally‐determined compression efficiency correlation, it is able to provide a simple and rapid way for designing.     

Quasi‐Self‐Similar Description of an Exhaust Jet

The method of construction of an analytical solution for the far field of an exhaust jet on the basis of the quasiselfsimilar solution of Prandtl equations and the turbulence model with one differential equation for the coefficient of kinematic viscosity is described. An exact numerical solution for distances to about 10¹ radii of the nozzle is constructed for the basic version. Then, a numerical solution and its analytical approximation by the quasiselfsimilar solution are constructed. Approximations of the similarity parameters of the selfsimilar problem as functions of the similarity parameters of the initial problem in the form of polynomials allow construction of analytical solutions for different situations, which are in satisfactory agreement with the exact numerical solution at distances of radii.