摘要:

In this work, a simple model is provided which accounts for any value of distribution coefficient of a solute, to describe the mass transfer for a batch process of extracting the solute between two immiscible fluids. A Lewis cell of constant interfacial area and a stirring tank were employed as the apparatuses for measuring the mass transfer rates of a solute between two immiscible phases. The model, which was based on the two‐film theory to determine the rate of mass transfer of solute across the interface, and the equilibrium concentration of solute at the interface, was derived and used to express the extraction of phenol. Experimental work, in which phenol was extracted from the aqueous phase to the organic phase by trioctylamine sulfate salts (TOA salts) dissolved in trioctylamine (TOA), was conducted to obtain the mass transfer coefficient. The effects of the operating conditions in a constant interfacial area cell and in the stirring tank are both discussed.

ISSN:0253-3839    

DOI:10.1080/02533839.1998.9670365

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

An on‐wafer surface charging sensor was developed for real‐time measurement of the local charging voltage during plasma processing. This sensor is based on a modified MOS capacitor structure with charging voltage built up between an electrode and the substrate across a thick oxide as an indicator of charging. An array of electrodes are designed to measure the local plasma charging condition across the wafer. The processes needed for this sensor manufacturing are fully compatible with present CMOS processes. Comparisons between different characterization methods of plasma charging are also discussed. This sensor can differentiate the charging condition for different process stages (on‐transient, steady state, off‐transient). In addition, this sensor provides a faster reading method of charging without further device measurements after plasma processing. From the experimental results of probe measurements in Ar, SF6and C2CIF5plasma, this probe shows excellent capability on real‐time monitoring of charging voltage. This sensor can be applied to IC plasma processing and equipment development, and trouble shooting in the future.

ISSN:0253-3839    

DOI:10.1080/02533839.1998.9670366

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Geographic information systems (GISs) are required to support a wide range of applications, many of which involve vast quantities of geographic data and a variety of data types, which include vector‐form and raster‐form spatial data as well as non‐spatial data. However, melting vector and raster data and expressing the natural associations between the spatial data and non‐spatial data in a GIS cannot be conveniently managed by the traditional record‐based system. A system based on an object‐oriented paradigm seems to be an appropriate candidate for effectively managing these data since the object‐oriented paradigm provides a basic and flexible modeling concept,object, and different modeling mechanisms, such as abstraction, encapsulation, and inheritance, to facilitate the representation and management of diverse geographic data. Thus, spatial data and its relevant non‐spatial data as well as the manipulations on them are tied together and represented by an object, which is the basic construction unit of a GIS application. In such a way, the underlying functions and structures of a GIS can be constructed by organizing objects to form a GIS shell, which is the kernel of a GIS. The design of an object‐oriented GIS shell based on notations given by the Object Modeling Technique (OMT) is described in this paper. In addition, features provided by the GIS shell are also discussed.

ISSN:0253-3839    

DOI:10.1080/02533839.1998.9670367

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

According to published research results, no directory‐based cache coherence protocol provides best performance for all application programs in conventional multiprocessor systems that use sequential consistency models. However, recently it has been claimed that competitive‐update protocols are superior to other protocols under a relaxed consistency model. Moreover, incorporating write caches improves the system performance of clean and competitive‐update protocols.

ISSN:0253-3839    

DOI:10.1080/02533839.1998.9670368

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

A microprocessor‐based adaptive pulse‐pump controller (μP‐APPC) for X‐Y mode frequency‐locked stepping position servo control system (XY‐FLSPS) is proposed. A control strategy inμP‐APPC for fasting the system locking process is developed. A discrete frequency set is built to represent the servo position so as to raise the accuracy of position lock and reduce the conversion error in the signal processing. TheμP‐APPC can respectively provide proper X's and Y's motion profiles for guiding their movements according to the detected position errors. An X‐Y pulse rate identifier (XY‐RI) is built to prescribe the instant X‐axis and Y‐axis motion speeds so that both X and Y motors can reach the target at approximately the same time. System modeling for analysis and computer simulation is constructed. A prototype of the XY‐FLSPS withμP‐APPC controller is developed for assessing system performance, and the X‐Y position and speed responses are described by three‐dimensional display.

ISSN:0253-3839    

DOI:10.1080/02533839.1998.9670369

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

The rapid growth in the number of Internet users makes Internet accessing speed increasingly slower. When applications that require a large amount of bandwidth, for example, the world wide web, are running through these snail‐like connections, delays and response time are often intolerable. Sometimes, the user's screen is stuck for a long time. World wide web becomes world wide wait. To increase responsiveness, a bandwidth sensitive hypertext transfer protocol is proposed in this paper. This protocol possesses the capability to match the amount and nature of the data transmitted with the amount of bandwidth available in the connection. That is, it tries to keep the communication going meaningfully and responsively as far as the connection bandwidth allows. This protocol can be applied to any situation where the available bandwidth is often inadequate and constantly changing. For example, in wireless networks where the connection bandwidth is limited and often variable, this protocol can be used to decrease response time and increase users’ satisfaction.

ISSN:0253-3839    

DOI:10.1080/02533839.1998.9670370

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

The quick buildup of higher pressure drop in the fixed‐bed reactor of a hydrotreating unit of a petroleum process is identified and improved. The results indicated that coke deposits formed in the catalyst bed are due to both the polymerization initiated by the dissolved oxygen in the presence of olefins, and the dehydrogenation reaction formed by hydrogen deficiency in the event of power failure in the unit. The buildup of pressure drop in the hydrotreating unit is improved by adding both an oxygen stripper in the feed stream to minimize the dissolved oxygen and catalysts with high void fraction and low activity in the top of the reactor to increase the tolerance of coke deposits. After revamping, the hydrotreating unit can operate at design throughput and the operation cycle time is not limited by the pressure drop. The results of this study are a breakthrough in the study of hydrotreating units. A correlation method was also developed to check the operation cycle time of the hydrotreating unit.

ISSN:0253-3839    

DOI:10.1080/02533839.1998.9670371

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

This study examines the effect of oil composition (including the anti‐static agent ‐ alkyl ether sulfate) on the physical properties and spread width of polyester multifilament for spinning a composite yarn. The results show that the solid content and viscosity of a special oil are slightly lower than normal oil, which reduces the stickiness of the spreading multifilament. Also, the coefficient of kinetic frictionμkand electrical conductivity of oiled polyester multifilaments are higher than normal oil in order to conduct and store charges, and to divide easily and spread widely to maintain good spreading performance. The content of the anti‐static agent is the most important component of a special oil. For example, the amount of alkyl ether sulfate (RO(CH2CH2O)nSO3Na) should be 14% to reduce electrical resistance, and increase spreading performance. Furthermore, the number n of oxyethylene groups(CH2CH2O) on alkyl ether sulfate is 2 or 3 in order to maintain a lower electrical resistance and wider spread width.

ISSN:0253-3839    

DOI:10.1080/02533839.1998.9670372

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

This paper presents a new method for factoring a self‐inversive Hermitian matrix polynomial relative to the unit‐radius circle. It formulates the factorization problem as that of evaluating a set of definite integrals along the unit circle and of solving a block‐Toeplitz system of linear equations. Since the evaluation of definite integrals along the unit circle can be accomplished via parallel computations and the solution of a block‐Toeplitz system can be obtained by a fast algorithm, the proposed method is very useful in real‐time applications.

ISSN:0253-3839    

DOI:10.1080/02533839.1998.9670373

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

The interaction of the fundamental and the subharmonic instability modes of an elliptic jet under excitations are investigated experimentally in this paper. Results indicated that the fundamental instability modef0saturated in the major axis location is almost the same as the subharmonic instability modef0/2 saturated in the minor axis. These two instability modes interact nonlinearly to produce the sum‐ and the difference‐modes. The newly produced instability modes grow and subsequently interact with other instability modes to produce other sum‐ and difference‐modes. A comb‐like spectrum resulted from the nonlinear interaction during the evolution process in the free shear layer of the elliptic jet flow.

ISSN:0253-3839    

DOI:10.1080/02533839.1998.9670374

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor