摘要:

In this paper, we present an experimental study on the effect of soluble surface active agents (SAA) on the exothermic absorption removal of gaseous pollutants with chemical reactions. Ammonia is absorbed into sulfuric acid solution, and isopropyl alcohol (IPA) is introduced as the soluble SAA in either the gas or in the absorbent liquid. Both the ammonia absorption rate and the surface temperature change are measured to examine the effect of soluble IPA impurities on chemical absorption systems employing a sulfuric acid solution.

ISSN:0253-3839    

DOI:10.1080/02533839.1995.9677661

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Triple Module redundancy (TMR) is a well known technique used in the development of a fault tolerance system. A system containing more than triple the redundancy may become a more preferable design choice, due to a rapidly progressing VLSI technology. Applications to the system; i.e. spacecraft controls and military communications equipment, must have a larger mean time to failure (MTTF) than TMR for a certain period of time. Massive redundancies will accomplish this. This, however, will also increase the complexity of the voter circuit. Using massive redundancies will cause the overall reliability of the system to decrease. A new configuration of a voter, called a self purging cascaded voter, has been proposed here for improving the conventionally used N module redundancy majority voter. The following advantages can be achieved by using this technique:i.TMR is the basic structure used here, without any concern as to how many modules this system may include. The design of the voter in NMR redundancy will, as a result, be simplified.ii.The reliability of a cascaded voter system is higher (approximately 12%) than that of a conventional majority voter system. A balance setting technique (a modified SPR) being used as the basic unit is suggested here for the best combination for the cascading system.iii.The complexity of the cascaded voter is much less than the conventional NMR voter (without cascading) as N increases.

ISSN:0253-3839    

DOI:10.1080/02533839.1995.9677662

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Experiments are conducted on tubular specimens of type 304 stainless steel. The effect of internal pressure is observed under the combined axial‐internal pressure loading. This experiment is utilized to verify the validity of endochronic theory of plasticity which has been shown to give reasonable predictions in a number of other loading conditions. In this investigation, a form of material function is proposed to govern the increment of intrinsic time such that it has a magnitude equal to unity upon reversed loading. The results of this investigation show that the theory generally does lead to favorable agreement with the experimental results. Especially, predictions of the Bauschinger effect are considerably improved.

ISSN:0253-3839    

DOI:10.1080/02533839.1995.9677663

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Penalty finite‐element solutions have been obtained for steady uniform flow from the left to the right over a clockwise rotating circular cylinder near a plane wall. Results are presented for Reynolds numbers 20 and 40, the non‐dimensional speed of rotation of the cylinder 0.0 ∼ 0.5 and the gap between the plane wall and the cylinder surface 0.2 ∼ 4.5 times the diameter of the cylinder. The motion is assumed to be two‐dimensional and to be governed by the Navier‐Stokes equations for incompressible fluids. The finite element approach is utilized and the frontal method is used to solve the stiffness matrix. In the cases of the cylinder without rotation, the results show that when the gap is large(H>2D), the effect of the wall makes the pressure on the cylinder surface decrease, andCl, CdandCtincrease. When the gap becomes small(H <2D), it makes the pressure andClincrease, andCtandCddecrease. For the gapH <0.7D, a recir‐culation zone is formed on the plane wall behind the cylinder. The smaller the gap, the recirculation zone is closer to the cylinder. The average rate of variation ofClandCdforH <1D isabout ten times those forH >1D.

ISSN:0253-3839    

DOI:10.1080/02533839.1995.9677664

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

The design of a robust feedback controller based on a cascade compensation method, a combination of the modified model feedback concept, and the internal model control (IMC) algorithm is proposed for a single input single output system in the presence of uncertainties. A model feedback concept is modified here to provide more design freedom and the possibility of greater robustness. Constraints which guarantee robust stability and robust performance are given. Finally, application of the proposed design method to control a deadtime system which is relevant for process control is demonstrated.

ISSN:0253-3839    

DOI:10.1080/02533839.1995.9677665

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

A mathematical model was developed to determine the sterility efficiency of a continuous high‐temperature/short‐time sterilizer for a liquid medium containing suspended particles of potato. A steam injection heating system, which is frequently used in industrial sterilization, was considered. Unsteady state balanced energy equations of the liquid medium and of the particles in the holding section and the cooling section were used to calculate the temperature distribution in the liquid medium, and also the particles as a function of time and inside position of the particle. The degree of sterility by the high temperature for the liquid medium and the particles was also calculated. It is shown that as the liquid medium achieved 16 orders of degree of sterility while in the holding section, the degree of sterility in the core of the potato is only 4 orders, which is far below the requirement. This phenomenon may cause a serious problem in the fermentation process. The results show that the cooling section predominates the sterility of particles. The degree of sterility for different potato sizes was also calculated. To meet the sterility requirement, increasing the residence time in the process or the sterilization temperature is required.

ISSN:0253-3839    

DOI:10.1080/02533839.1995.9677666

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Acetal compounds were synthesized by reaction of various alcohols and dibromomethane in an organic solvent and alkaline aqueous solution of KOH using quaternary ammonium salts as a phase‐transfer catalyst. We have greatly enhanced the efficiency of the reaction by adding quaternary ammonium salt in small proportions. A unique final product with two alkoxy substituents indicating a rapid second reaction was obtained in the organic phase. A pseudo‐first‐order rate law was used to describe the reaction only at large KOH concentration. At a small KOH concentration, the system was controlled by the chemical equilibrium of KOH and alcohol present at a limited concentration in the aqueous phase, whereas it was controlled by the reaction in the organic phase at a large concentration of KOH. The effects of the reaction conditions and parameters on the conversion of dibromomethane were investigated in detail. We have improved the reaction to obtain a high yield and a rapid rate by using a large concentration of KOH in a small volume of water and a solvent of appropriate polarity. Tetrabutylammonium bromide (TBAB) provides a high yield of product.

ISSN:0253-3839    

DOI:10.1080/02533839.1995.9677667

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

A study was initiated to observe the concentrations of different nitrogen species in pore water and the solid phases of sediments. Additionally, nitrogen release, ammonium desorption, and denitrification rates in lake sediments were experimentally performed. For an eutrophic lake, the average denitrification rate was approx 14.6 mg N/m2·h within a 5‐cm layer of the sediment; the rates decreased with an increase in sediment depth. By considering adsorption, desorption, and denitrification processes, a model was developed to describe the transformation of nitrogen species between the sediment and the aqueous solution and to predict the effects of nitrogen forms in sediments on the water quality of the overlying water bodies.

ISSN:0253-3839    

DOI:10.1080/02533839.1995.9677668

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

To account for most of the important sources and to minimize the impact of uncertainties of boundary conditions, a rather large domain is usually needed in Eulerian air quality modeling. For selected areas such as in the vicinities of large point sources or urban centers, smaller grid sizes are needed to achieve acceptable resolution. Consequently, a combination of different grid sizes is desirable for an optimal balance in resolution and computational cost. Pleim et al. had established a one‐way nesting process in which information from the coarse grid model is passed to the fine grid subdomain model, but not in the opposite direction. A new two‐way nesting process based on the concept of error correction is proposed. This process can be self‐consistent compared to the two grid systems. We have made comparison between the two nesting processes using the Bott advection scheme in numerical experiments and evaluated their performance in air quality modeling. Wherever the two‐way nesting process is used, we have relatively better results compared to the one‐way nested subdomain model.

ISSN:0253-3839    

DOI:10.1080/02533839.1995.9677669

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Several high performance microprocessor systems have been developed in recent years. Other than the fact that the system clocks were pushed to a higher rate than before, these systems were improved throughout by issuing more than one instruction within a cycle. Due to their increasingly complex pipeline structures as well as employment of multiple functional units, object codes of these systems are in general required to be reorganized in order to keep functional units busy and to avoid pipeline interlocks. Success of such a system design hence depends on not only how many hardware resources it provides, but primarily how efficiently these resources can be utilized.

ISSN:0253-3839    

DOI:10.1080/02533839.1995.9677670

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor