ISSN:0253-3839    

DOI:10.1080/02533839.1989.9677161

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

This study aims at establishing empirical correlations for the soil deposits in Taipei City. These correlations are valuable in the planning and preliminary design stages. For cohesive soils, correlations between (1) virgin compression index and nautral water content, (2) virgin compression index and initial void ratio, (3) coefficient of consolidation and liquid limit, and (4) angle of shearing resistance and plasticity index are proposed. Profiles of overcons‐olidation ratio (OCR) as well as strength ratio are presented. Relationships between the coefficient of earth pressure at rest and the angle of shearing resistance and the plasticity index have also been carefully studied. For cohesionless soils, correlations between (1) permeability and effective particle size, and (2) angle of shearing resistance and standard penetration test (SPT) TV‐value are presented. Due to inherent variations in the Taipei soil deposits, there are practical limitations and the correlations presented in the paper should be used with great care.

ISSN:0253-3839    

DOI:10.1080/02533839.1989.9677162

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

In this paper, a robust simplified adaptive controller is proposed to control the motion of a one‐link flexible robot arm. In the proposed controller, the natural frequency of the first vibration mode is identified, and the output feedback control algorithm with time‐varying gains is employed. The stability of the controlled system is proved through the use of the second Liapunov's theorem. Then, experiments are carried out to evaluate the perfromance of the proposed controller. It is found from the experimental results that the performance of the adaptive controller is satisfactory. Also, it is shown that the proposed controller is robust to parameter errors or variations.

ISSN:0253-3839    

DOI:10.1080/02533839.1989.9677163

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

A kinetic study of the Wittig reaction for synthesizing stilbene is carried out by reacting benzaldehyde (C6H5CHO) with benzyltri‐phenylphosphonium bromide (BTPPB) in the NaOH(aq)/CH2Cl2(org) two‐phase reaction system. The rate of reaction depends on the agitation speed, the temperature and the concentrations of C6H5CHO, BTPPB, and NaOH. When the agitation speed is low, the reaction is highly affected by interface diffusion. The reactant rate constant, based on theSN2 substitution mechanism and the activation energy are also determined. It is found that the activation energy obtained from the present study (Ea=11.97 kcal/mole) is less than that of the previously documented data (Ea=12.984 kcal/mole) in which benzyltriphenylphosphonium chloride (BTPPC) was used as a phase transfer catalyst.

ISSN:0253-3839    

DOI:10.1080/02533839.1989.9677164

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

In the last decade several primitives of quad trees have been proposed as data structures for the hierarchical design of VLSI. This paper presents algorithms, implementation, and experimental results of a hierarchical mask layout compaction scheme based on a fast region‐query and space‐efficient data structure called the hierarchical multiple storage quad tree. Contrary to symbolic compaction, this mask layout compaction is based on rectangle edges rather than symbols. A new method for the generation of a constraint‐graph is proposed in detail by using an alternative dynamic event scheduling algorithm (DES algorithm) in 2‐Dspace. This is a new plane sweep method based on the multiple storage quad tree and is capable of being extended to support the inherent problems in computational geometry and image processing. Some important features of the mask layout compactor: such as error‐tolerance, mixed‐constraint, grid‐freeness, and hierarchical design and amalgamation, are described in this article. In consequence, we have successfully accomplished the layout compactor in practical linear time performance in terms of the rectangles in the VLSI layout.

ISSN:0253-3839    

DOI:10.1080/02533839.1989.9677165

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

In this paper, a cost function considering execution time, communication time and even idle time, is employed to measure the performance of task assignment in a distributed computing system. We successfully develop a new mathematical model to describe this kind of cost function. The task assignment problem is formulated as one of directed‐to‐undirected graph mapping (DU‐mapping) which maps a directed acyclic task graph onto an undirected system graph. The search of optimal DU‐mapping is NP‐complete and is transformed into a state space search problem. Using an underestimation toA*algorithm, we can obtain an optimal DU‐mapping and prune the most nodes in a state space tree. An alternative overesti‐mation is applied to prune more nodes but also obtain a suboptimal DU‐mapping. Results of a wide range of experiments reveal that both estimates perform very well due to close evaluation of the real cost.

ISSN:0253-3839    

DOI:10.1080/02533839.1989.9677166

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

With little error, taking assumption of sinusoidal current distribution on the half‐wave dipole for exact (near and far) field and using the geometrical optics (GO) theory for ground reflection, a simplified yet improved method is derived for calculating site attenuation in terms of the antenna factors of transmitting and receiving antennas. The near field and mutual coupling problems that have caused errors between theoretical and measured data in the past can be easily solved. The deviation in the site attenuation curve due to equipment impedance mismatch and dissipative losses is also discussed. The results obtained by using this method show a good agreement with those obtained by Kawana using the moment method (MM) (for 3 meter site) and those measured by the National Bureau of Standards of U. S. A. (NBS) (for 3, 10 and 30 meter sites), while much more calculating time is saved. That is, this method provides a more effective solution for evaluating theoretical site attenuation of a standard open site.

ISSN:0253-3839    

DOI:10.1080/02533839.1989.9677167

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

The performance of a communication system in a hostile environment can often be evaluated by game theory. If one chooses the payoff appropriately, then the results of finite two‐person zero‐sum games are directly applicable. In this paper, we study the performance of a communication link with two data rates in the presence of a hostile jammer. Ensemble mean of the time average throughput is defined as the payoff to the communicator and the system is modeled as a two‐person zero‐sum game. The saddlepoints as well as the value of the game are determined for both symmetric and asymmetric communication strategy cases. Some results for similar systems have been obtained and discussed in Ref. [5]. However, in this paper, we allow the jammer to locate himself in some region at his will, and hence include the model discussed in Ref. [5] as a special case. It is found that the payoff to the communicator is larger if an asymmetric communication strategy is adopted. Like the conclusion stated in Ref. [5], the system results obtain from optimal asymmetric communication strategy may become non‐ergodic. The results obtained analytically are applied to a practical and interesting example.

ISSN:0253-3839    

DOI:10.1080/02533839.1989.9677168

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

The major advantage of token‐passing‐bus local area networks (LANs) is its collision‐free characteristic but its drawback is the overhead in passing the token to idle users when the channel load is light. It is commonly known that the system performance can be increased considerably by increasing the capacity of the bus. One way of increasing the bus capacity, and also the system reliability, is to increase the number of buses. In this paper, we propose adding a second bus to provide high bandwidth as well as reliable service for token‐passing‐bus LANs. The second bus proposed here normally is used for reservations so that the token on the data bus is dynamically passed to ready users for packet transmission. Furthermore, it will take the place of the data bus when the data bus fails. The protocol discussed here is a reservation token‐passing protocol which not only is collision‐free but also minimizes the token‐passing delay. The analysis of this dynamic token‐passing protocol is provided with both analytical results as well as simulation results.

ISSN:0253-3839    

DOI:10.1080/02533839.1989.9677169

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

This paper presents a visual programming environment for users to develop their own defined icon‐based Chinese input methods. It will show the following four aspects. First, Chinese characters are concrete icons (decomposition graphs or webs). Second, a grammar that generates the above mentioned webs is a context‐free web grammar. Third, an icon‐based Chinese input method defines semantic rules to the production rules of the web grammar which then becomes an attributed web grammar. Fourth, a Chinese input simulator is a machine that accepts these webs. Developing such a simulator can be regarded as the construction of a user‐defined application program under the proposed visual programming environment. This paper also shows that form‐based visual languages included in the environment can be used to specify ways of evaluation and simulation in the user‐defined simulator.

ISSN:0253-3839    

DOI:10.1080/02533839.1989.9677170

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor