ISSN:0253-3839    

DOI:10.1080/02533839.1992.9677411

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Noise analysis of buried channel CCD by computer simulation is presented. The potential profile and signal charge distribution in potential well are obtained by solving Poisson's equation with a depletion approximation model. According to this model, it is possible to predict the volume occupied by signal charges in potential well. Thereby, the well capacitance and free carrier density are obtained. Then the device noise in the buried channel charge‐coupled device, including the output reset noise, dark current noise, transfer noise and electrical injection noise at the input, can be calculated. Also, the charge handling capacity can be evaluated by integrating over the charge occupied volume.

ISSN:0253-3839    

DOI:10.1080/02533839.1992.9677412

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

The instability caused by aerodynamic forces from blade‐tip clearance is one of the most troublesome problems found in high performance tur‐bomachinery. An optimization technique has been proposed in previous work to improve the stability of a rotor‐bearing system. In this work, the validity and the practical procedure of the optimization technique are experimentally verified and demonstrated using a rotor‐bearing system. The experimental results verify the important theoretical conclusion that the threshold of stability of a rotor‐bearing system can be significantly increased by slight modification of the rotor diameters. Two examples are given to show the detailed procedure when the proposed optimization technique is used to increase the threshold of stability of an existing rotor‐bearing system.

ISSN:0253-3839    

DOI:10.1080/02533839.1992.9677413

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Laboratory experiments conducted in a wave basin with movable sand bed have shown that, under the action of 2‐D standing water waves, longitudinal sand bars with small ripples riding on their tops are formed beneath the nodes of standing waves. Wavelengths of the sand bars are approximately equal to one‐half of those of standing water waves. The formation of sand bars under standing waves over an initially horizontal sand bed is explained by the suction and impinging effects of the wave action. A mathematical model for describing the induced density of sediment‐water mixture due to wave action is proposed. By employing the induced‐density model and mass conservation of sediment‐water mixture, a numerical simulation model is constructed. Bed configurations resulting from the actions of 2‐D standing waves are studied by using the simulation model. The simulation results of sand bed configuration under the action of 2‐D standing waves are in good agreement with those obtained from laboratory experiments.

ISSN:0253-3839    

DOI:10.1080/02533839.1992.9677414

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

The governing equations for switched‐capacitor band pass filters are greatly simplified into a new set of much simpler equations, with no approximation involved. For sharp band pass filters with narrow bandwidths, we expand the new set, cancel out many leading terms, and get a set of new formulae. Based on these formulae, we obtain and tabulate numerical design data for sharp 4th to 8th order Butterworth band pass filters, including values for the required resistors. The application of switched‐capacitor filters MF5 and MF10 is then greatly expanded to cover sharp and very sharp band pass filters.

ISSN:0253-3839    

DOI:10.1080/02533839.1992.9677415

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

The parameters of anaerobic digestion include not only those of anaerobic biological reaction, but also those of the related operational‐physical characteristics, such as dispersion, diffusion, cell accumulation and transportation. In this paper, we conduct a laboratory experiment to find out the relationship between design‐operation parameters with dispersion, and combine this information with physical characteristics to set up the “dispersion model”. Then, we analyze the feasibility of a dispersion model in anaerobic filter digester simulation.

ISSN:0253-3839    

DOI:10.1080/02533839.1992.9677416

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

A modified gravity arc welding installation has been used to study underwater welding and the weld metal characteristics under simulated laboratory conditions. The constant deposition of metal per unit length of the weld, independent of the electrode consuming rate, could be controlled by a given electrode leading angle. X‐ray radiographie inspection revealed that only few detectable defects, in addition to undercuts, were presented in the underwater welds. Fractographic observations have shown that many fine inclusions existed; however, microcracks and microvoids were rather few in the deposit. Microcracks, if any, generally propagated along the columnar grain boundary ferrite and arrested in the region of acicular ferrite. The correlations between fracture and microstructure have indicated that the grain boundary ferrite and associated Widmanstätten side plates induced the brittle fracture, while acicular ferrite led to a ductile type of failure.

ISSN:0253-3839    

DOI:10.1080/02533839.1992.9677417

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Using the conformai mapping technique, the elastic interaction between a screw dislocation and an internal crack in a thin plate material is investigated. The stress field, the stress intensity factor at the crack tip, and the force on the dislocation are derived. The stress intensity factor at the crack tip is dependent on the positions of the lattice screw dislocations, the dislocations inside the crack, the applied stress and the geometry of the medium. From the image force, the zero‐force points between the crack tip and free surface are obtained. The number of zero‐force points varies from one to five depending on the applied stress and dislocations inside the internal crack. Finally, our results can be reduced to several special cases.

ISSN:0253-3839    

DOI:10.1080/02533839.1992.9677418

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

In this paper, a simple practical analytic method is proposed for designing multiloop‐controlled pulse width modulation (PWM) switching regulators. First, an equivalent single loop gain is presented and an approximate optimal set of closed‐loop poles is suggested according to the given specification such that the familiar design concept of a single‐loop second order system can be applied directly. In particular, closed form expressions of the feedback gains and the unknown parameters of the standard implemented circuit are derived. This renders the implementation problem surprisingly simple. Finally, some experimental results are also presented to demonstrate the effectiveness of the proposed method.

ISSN:0253-3839    

DOI:10.1080/02533839.1992.9677419

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Undrained cyclic triaxial tests are performed on specimens of Ottawa sand to study the evolution of fabric during undrained cyclic loading. Isotropic consolidation tests and triaxial drained compression or extension tests are conducted before or after cyclic loading to characterize the state of fabric indirectly. The effects of stress path, cyclic stress ratio, cyclic number, and initial fabric on fabric evolution during undrained cyclic loading are investigated.

ISSN:0253-3839    

DOI:10.1080/02533839.1992.9677420

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor