ISSN:0253-3839    

DOI:10.1080/02533839.1989.9677209

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

The objective of this study is to investigate the seismic wave propagating in dipping layered medium. Firstly, the assumption for the omission of diffraction and radiation of waves by the apex of a wedge is made when both source and the receiver are at large distances from the apex, and when the angle of inclination is small. For such cases, the generalized ray theory is employed as a mathematical tool to solve the aformentioned problem, of which the source function for transient shear fault is derived. Then, the construction of ray integral, which is in the form of Laplace transform, is inverted by the well‐known Cagniard method. Hence, from the obtained results, it shows that the responses in up‐dipping medium are larger than those in down‐dipping medium, and the energy decays with the numbers of reflection.

ISSN:0253-3839    

DOI:10.1080/02533839.1989.9677210

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

MOSFET's and MOS memory devices suffer the increase of interface state density and oxide trapped charge density after ionization radiation such as gamma rays. The drain‐current dependence and the gate‐voltage dependence of the flicker noise of the irradiated MOSFET's are illustrated in this paper. The annealing effect, the bias effect, and the total dose effect on the noise behavior are shown. It is also shown that the change of the interface state density is essential to the noise change and the change of oxide trapped charge density may cause the “apparent” change of MOSFET's flicker noise after gamma irradiation.

ISSN:0253-3839    

DOI:10.1080/02533839.1989.9677211

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Some popular stability problems, such as “even if all eigenvalues of a linear time‐varying system are independent of time and have negative real parts, the system can be unstable”, are explained reasonably in this paper. We also give interesting examples to show that even for a stable system, its transposed system may be unstable. All the discussions are brand‐new.

ISSN:0253-3839    

DOI:10.1080/02533839.1989.9677212

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

In this paper, the performance of several speech recognition techniques applied on the highly confusing Mandarin syllables were carefully compared, including dynamic time warping (DTW), the newly proposed DTW with superimposed weighting function (DTWW), the discrete hidden Markov models (DHMM) and the continuous hidden Markov models (CHMM). The vocabulary used here consists of 409 first tone isolated Mandarin syllables. Due to the fact that many confusing sets exist in this vocabulary, the accurate recognition of these syllables is relatively difficult, and all the recognition experiments were performed in the speaker dependent mode. After a series of 13 experiments, it was found that the recognition rate of the newly proposed DTWW (88.3) is higher than that of DTW (85.1), DHMM (65.0) and CHMM (83.9), and that the CPU time used for DTWW is 1.03 times that for DTW, 24 times that for DHMM and 4.3 times that for CHMM. In addition, the memory space required for DTWW and DTW is 3.4 times that of DHMM and 8.5 times that of CHMM. Therefore, DTWW has the highest recognition rate, DHMM has the fastest recognition speed, whereas CHMM appears to be very attractive when all the different factors including recognition rate, recognition speed and memory space requirement are considered.

ISSN:0253-3839    

DOI:10.1080/02533839.1989.9677213

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

The purpose of this work is to study the radiation heat transfer through some typical ultra‐fine powder insulations. The spectral extinction coefficients for these powders have been measured via infrared transmission measurements. The experimental results are compared with both the dependent and independent scattering and absorption theoretical calculations. The radiative transport process is modeled by the diffusion approximation method. Based on the experimental data, the radiant thermal conductivity between two concentric cylinders and spheres was calculated. The results show that the radiant thermal conductivity between two concentric spheres is about 50 percent higher than that between two cylinders.

ISSN:0253-3839    

DOI:10.1080/02533839.1989.9677214

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

This work studies the combustion and gasification behavior of individual coal particles in a hot environment. The model contains (1) heat and mass transfer and pyrolysis within the particle, (2) thermal radiation, diffusion and combustion of the reactive gases outside of the particle. The stages of preheating, ignition, and combustion are discussed separately.

ISSN:0253-3839    

DOI:10.1080/02533839.1989.9677215

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

In this paper, the details of the experimental techniques and set‐ups needed in the acoustic birefringence measurement are given. To precisely determine the wave speeds, the Echo‐Overlap method with reflection mode is adopted. The details of the fabrication of a dual‐polarization ultrasonic shear‐wave transducer are also included. The anelastic effect which occurs in the acoustoelastic measurement of a plastically deformed steel (C1018) specimen is examined. The general assumption of slight orthotropy which is used in ultrasonic stress measurement of polycrystalline metal is tested. The annealing experiment shows that the preferred orientation of the cold‐rolled steel plate can not be changed by annealing the specimen at the recovery temperature. The measurement of the third order elastic constants of the steel specimen is also conducted.

ISSN:0253-3839    

DOI:10.1080/02533839.1989.9677216

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

The present work analyzes the problem of vapor condensation in porous media. Specific consideration is given to a transient‐state one‐dimensional formulation, representing a porous slab exposed to the saturated vapor from one side and the cold plate on the other side. When condensation occurs, three zones will exist inside the porous medium. Near the cold plate, a liquid zone is expected. Adjacent to this zone and extending into the medium will be a two‐phase zone which is dominated by capillary and vapor phase transport. Ahead of this zone the medium will remain saturated with vapor phase. Predictions from the three‐zone model used in this study have been compared with the two‐zone model which neglects the effect of surface tension forces. The results show that the two‐zone model can only predict the condensation phenomena in low permeability media. Capillary pressure or surface tension effects become significant and cannot be neglected during the condensation of vapor in high permeability media.

ISSN:0253-3839    

DOI:10.1080/02533839.1989.9677217

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Stress corrosion cracking (SCC) of zircaloy cladding is generally believed to be the major failure mode of current nuclear fuel in light water reactors. Iodine, an abundant fission product, has been identified to possibly cause zircaloy to become susceptible to SCC. An understanding of the kinetics of the reaction between zirconium and iodine is an essential part of the complex iodine induced SCC mechanism. The kinetics of reaction between zirconium and iodine are investigated by TGS‐2 thermogravimetry system at the temperature range of 300∼350°C. Results show that the activation energy, pre‐exponential factor and reaction order of molecular iodine are 43.8 kJ/mole, 3.1 mg/cm2‐min and 1.06, respectively. A study of the effect of surface texture on the kinetics is also performed by using the different cold rolled specimens whose textures are examined by an X‐ray diffraction method. Cold rolling will shift the basal pole to the rolling direction and only influence slightly the pre‐exponential factor. The results on zircaloy‐4 also indicate that it exhibits better corrosion resistance in the iodine vapor as compared to zirconium.

ISSN:0253-3839    

DOI:10.1080/02533839.1989.9677218

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor