Numerical‐Analytical Investigation of Self‐Similar Regimes of Propagation of Nonstationary Convective Jets and Thermals in a Homogeneous Medium over a Point Heat Source

An integral model of a nonstationary vertical convective jet is suggested that involves a universal equation of the propagation of the upper boundary of a convective front depending on the power of the point heat source. A class of selfsimilar solutions is considered; they correspond to the heat sources whose power changes instantly and also according to the power and exponential laws. Analytical and numerical solutions of the selfsimilar equations are constructed. Numerical calculations are compared with the wellknown experimental data on the profiles of the vertical velocity and temperature on the jet axis.     

Influence of the Random Structure of an Initial Material on the Processes of Self‐Propagating High‐Temperature Synthesis in Thin Films

Numerical simulation of the process of selfpropagating hightemperature synthesis in twodimensional systems, the physical prototypes of which are thin films, has been performed. The emphasis has been on consideration of the heterogeneity of the system and randomness in the spatial arrangement of its different components. It has been found that taking into account the randomness factor, all other things being the same, leads to a substantial change in the basic characteristics of both the combustion process (for example, of the wave velocity) and the end product of synthesis. It has been demonstrated that, first, the critical level of external heat loss decreases significantly as compared to the case of a uniform distribution of the reagents and, second, this characteristic undergoes an abrupt increase in the vicinity of the reagent concentration corresponding to the percolation threshold for the lattice used in simulation. A qualitative comparison of the simulation results with experimental works has been carried out.     

Quasi‐static analysis of electric and magnetic fields in tem cell

Abstract

A method is presented whereby the electric and magnetic fields within a rectangular coaxial transmission line (TEM cell) can easily be obtained. The analysis is based on the variational technique in the space domain combined with the Green's function method. Numerical data are presented for the characteristic impedance and for the field distributions within the cell. The results calculated by the present method are found to be in good agreement with those in open literature.     

Numerical Analysis of the Jet‐Vortex Pattern of Flow in a Rectangular Trench

Numerical simulation of the vortex structure of threedimensional laminar flow in a rectangular trench of square cross section has been carried out on the basis of the finitevolume solution of steadystate Navier–Stokes equations.     

Description of the Shape Memory Effect of Radiation‐Modified Polymers under Thermomechanical Action

The shape memory effect of crystallizing polymer materials is simulated. The polymer is considered to be an inhomogeneous medium with a moving boundary (temperaturedependent phase composition). Using a model based on the frozen strain hypothesis, the temperature dependences of stresses under isometric heating and cooling have been obtained. On the basis of the known data on the influence of irradiation on the thermomechanical characteristics the dependences of thermorelaxation and thermoshrinkage stresses on the absorbed dose for highdensity polyethylene have been found.     

Distribution of Impact Momenta over a Surface Treated with a Water‐Drop Jet

A model of a random field of the momenta of impact forces acting on a plane surface treated with a waterdrop jet has been developed. Based on the calculation and experimental data, it is shown that the action of individual drops is statistically independent in time and coordinates.     

Techno‐economic evaluation and sensitivity analysis of an energy‐recovery system

Abstract

A computation algorithm for the techno‐economic evaluation and sensitivity analysis of an air‐preheated energy recovery system is presented. Through the study, we find that different equipment designs of the same project affect the benefit of the recovery system remarkably. It is therefore necessary to consider technical and economic factors simultaneously to obtain a reasonable evaluation result for an energy recovery project. The sensitivity study shows that the annual operating hours is the primary factor in the profitability of an energy recovery system; thus, the reliability of the recovery system should be considered as the investment decision is made. In brief, this article offers the concepts of economic optimization for an energy recovery system.     

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.     

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 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.     

Design of an adjustable‐way cache for energy reduction

Abstract

Conventional set‐associative caches, with higher associativity, provide lower miss rates. However, they suffer from longer hit access time and larger energy dissipation. Based on the consideration of different program localities, programs should have their own appropriate associativity of caches. In this paper, we propose a set‐associative cache that can provide flexibilities to adjust its associativity according to different program behaviors, which means that the proposed cache scheme can be adjusted from an n‐way set‐associative cache to a direct‐mapped cache. By use of this cache architecture, power consumption can be lowered when an n‐way set‐associative cache configures the cache with lower associativity (less than n) due to only enabling fewer subarrays of the tag memory and data memory. However, the performance is still maintained at the same level as in a conventional set‐associative cache or direct‐mapped cache. Adjustable‐way set‐associative caches can also be applied to multiprocessor systems to reduce the average, overall system, energy dissipation.     

Change of the Sign of the Effect with Increase in the Intensity of High‐Frequency Acoustic Excitation of a Turbulent Jet

Results of an experimental investigation of highfrequency acoustic excitation of turbulent jets for different intensities of the acoustic field are presented. It is shown that upon reaching a certain limiting level of excitation at high frequencies, the sign of the effect changes, i.e., at this level, highfrequency excitation leads to generation of turbulence in the jet rather than its suppression. Hence it follows that the highfrequency acoustic effect that suppresses turbulence is most efficient within an optimum range of frequencies and at an optimum level of excitation.     

Self‐Cooling of a Gas, Absorbing Laser Radiation, Due to the Intensification of Photoabsorption Convection

The effect of decrease in the temperature of an absorbing gas in a volume occupied by the beam of a continuously operated laser with decrease in the beam diameter has been investigated experimentally for the case of constant radiation power. Based on theoretical evaluations it has been inferred that the intensification of photoabsorption convection is the reason for the temperature decrease. It has been shown that an optimum diameter of the beam exists for which (for a given radiation power) the temperature of the absorbing gas attains its maximum (accordingly the maximum is attained by the yield of the reaction of thermal decomposition of the gas in the case of its pyrolysis). When the diameter is optimum the heat loss from the beam volume by heat conduction is equal to the heat loss by photoabsorption convection. It has been inferred that in constructing an adequate theoretical model of laserinduced chemical vapor deposition it is necessary to take into account the convection.     

Control of an Error of a Finite‐Difference Solution of the Heat‐Conduction Equation by the Conjugate Equation

The results of the calculation of temperature by the finitedifference method can be verified and the value of the remaining error can be estimated by the conjugate problem with a moderate expenditure of computer resources.     

The design of an intelligent real‐time autonomous vehicle,TAIWAN iTS‐1

Abstract

Developed at National Chiao Tung University, TAIWAN iTS‐1 is the first smart car with active safety systems and comfortable autonomous driving in Taiwan. An adaptive vision‐based lane detection algorithm was proposed to help the lateral control unit to keep the car in its lane safely. It also carries a DSP system to generate warning signals for unintentional roadway departures. A laser radar measures the distance between the preceding car and TAIWAN iTS‐1. With this information, the longitudinal control unit performs intelligent cruise control and stop‐and‐go functions. The remote control function is realized on TAIWAN iTS‐1 for safety testing and military applications. Unlike most smart car studies, this paper considers not only driving safety demands but also non‐driving security. An active mobile surveillance system will inform the car owner when the car is illegally broken into, anytime and anywhere. For drivers and passengers, the perception of comfort is achieved by intelligent vehicle dynamic control. All functions integrated into TAIWAN iTS‐1 have been tested repeatedly on National Highway 3 and Expressway 68 in the Hsinchu area and the system's robustness has been successfully demonstrated in these real‐road experiments.     

Heat‐Source‐Initiated Thermoelastic State of a Semiinfinite Plate with an Edge Crack

A study is made of the influence of the internal heat source on the factors of intensity of the stresses at the tip of an arbitrarily oriented edge cut in a homogeneous halfplane.     

Self‐Organization and Dynamic Chaos in Chemical‐Technology and Heat‐Exchange Devices: Problems and Tasks

Nonlinear phenomena in thermophysical and chemicaltechnology processes are considered in the context of nonlinearity, instability, nonuniqueness, nonstationarity, and irreversibility. The perturbation frequency (phase)toamplitude ratio is the governing parameter of the nonlinear interaction of perturbations that are described by the proposed general nonlinear parabolic equation. The nonlinearity of this ratio characterizes turbulence, while its linearity characterizes selforganization. It is shown that chaotic conditions can be selforganized under the action of white noise, which favors the system getting into the domain of attraction of a stable node. The mechanism of the occurrence of turbulence is substantiated.     

Filtration of a High‐Viscosity Oil in an Electromagnetic Field

Results of experimental investigations of the time dependences of the change in the temperature of an oil pool and in the discharge of an oil well under the action of a microwave electromagnetic field are presented. An experimental setup is described. It is shown that the temperature is distributed nonuniformly over the thickness of the oil pool depending on the initial discharge of the well and the time of the microwave electromagnetic action on the face zone of the pool.