摘要:

AbstractA piezoelectric interdigital transducer (IDT) normally used for SAW devices can emit high frequency ultrasonic waves into water. To make use of this phenomenon in an acoustic imaging system, characteristics of longitudinal waves radiated from the IDT into water and the radiation mechanisms using the ASPW method were investigated. It was found that two types of longitudinal waves are radiated from the IDT and one of them can be beam‐scanned by changing the frequency. Finally, a focussed ultrasonic wave was obtained from an arched IDT in water and the surfaces of several objects were observed with good resolutio

ISSN:8756-6621    

DOI:10.1002/ecja.4410650702

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1982

数据来源: WILEY

摘要:

AbstractSome applications of microwave distributed‐line networks have recently become known in the field of ultra high‐speed (gigab its per second) digital communication systems as signal‐processing or waveform‐transformation networks. constant‐resistance, two‐strip, n‐section coupled‐line bridged‐T networks constructed on thin‐film substrates in aplanar‐structure. An equivalent signal flow‐chart is given for an n‐section coupled‐line which is part of the bridged‐T network. This signal flow‐chart shows that both numerator and denominator of the transfer function of the bridged‐T network have real‐coefficient rational functions of order n with respect to 2‐1. However, depending on the choice of element values of the bridged‐T network, we can obtain a non‐recursive transfer function in which the denominator is constant, or a recursive transfer function i n which the numerator is constant. It is demonstrated that in this case all reflection coefficients for the backward‐traveling power waves must be zero in the n‐section coupled‐line. AS a result, the bridged‐T network ma? be used as a digital frequency multiplier, as a code converter lacking the characteristic wave distortion, or as a wavefo

ISSN:8756-6621    

DOI:10.1002/ecja.4410650703

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1982

数据来源: WILEY

摘要:

AbstractThis paper describes a method for determining the coefficients of a transfer function. In this description when the ideal two‐dimensional Markov parameters and the orders of the separable‐denominator two‐dimensional transfer function are given, the two‐dimensional Markov parameters generated from this transfer function will give the best approximation to the ideal two‐dimensional Markov parameters over a designated finite interval. To minimize the performance measures in this paper, the optimization technique proposed by Evans and Fischl for the time‐domain design of one‐dimensional digital filters is extended to this two‐dimensional case. Their technique has the merit of easy judgement of stability because the two‐dimensional digital filters are designed using a separable‐denominator two‐dimensio

ISSN:8756-6621    

DOI:10.1002/ecja.4410650704

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1982

数据来源: WILEY

摘要:

AbstractThe degree of IC integration has shown yearly increases. Hence, the amount of layout data also has increased. Therefore it is very important to verify that a given circuit is realized correctly on a layout. To simplify verification we reconstruct the diagram of a given circuit from its layout data. We present an algorithm for reconstruction and describe a system which incorporates it. The circuit diagrams reconstructed by this algorithm resemble these drawn by layout designers. Hence it is a very effective means of layout verification. In this algorithm we use a graph to show the interconnections of transistors given by layout data. We group transistors into a number of subgroups so that each group forms a logical unit. Then we determine the positions of the transistors within each group and the positions of the logical units. Finally we reconstruct a circuit diagram resembling the hand drawn one by determining the final positions of the transistors of the circuit based on those positions.

ISSN:8756-6621    

DOI:10.1002/ecja.4410650705

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1982

数据来源: WILEY

摘要:

AbstractThis paper uses the constant group average degree model, which is a generalization of the constant average degree model, and evaluates the method of solution given in [1] to determine the independent vertex set. The model is a set of graphs in which there exist edges with probability pij= cicj/cn (c Σmi=1ci|Vi|/n) independently between two vertices v and w such that v ϵ Viand w ϵ Vjin the vertex set V = Umi=1Vi. When m = 1 holds as a special case, the model includes the constant average degree model. It is shown first that the stochastic variable BG(n, c) representing the solution by the method of [1] satisfies (1 ‐ ϵ) βG(c)n

ISSN:8756-6621    

DOI:10.1002/ecja.4410650706

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1982

数据来源: WILEY

摘要:

AbstractExisting facsimile compression schemes include the CCITT recommendation T.4 for a one‐dimensional modified Huffman scheme and the optional 2‐dimensional modified READ scheme. This paper proposes a 2‐dimensional coding method using the corner edge points of a contour line. The features and characteristics of this method are compared to those of the modified READ and other 2‐dimensional methods. The amount of encoded data in the conventional methods generally increases quadratically with the scanning resolution. In coding a contour line, however, the amount of data increases linearly with scanning resolution. Furthermore, only the corner points, not the straight line segment between them, need to be encoded for a contour line with straight edge. This is one of the reasons why the proposed method is more efficient for data compression than the conventional 2‐dimensional methods such as the modified RE

ISSN:8756-6621    

DOI:10.1002/ecja.4410650707

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1982

数据来源: WILEY

摘要:

AbstractHyperthermia (heating therapy) has attracted attention as a possible cancer therapy. Hyperthermia treats an affected area with heat. It is effective alone and its effect is multiplied when combined with other treatments. Many heating devices already proposed limit their heating to the surface; therefore, proposals for devices which can perform deep heating are strongly demanded. This paper proposes an applicator for hyperthermia which provides deep heating by exciting in‐phase dipole elements arranged on a circumference. Theoretical study is conducted to determine numerically various parameters of the proposed applicator and its temperature rise during heating. It is shown that deep heating with less overheating on the surface is possible with this proposed applicator. Furthermore, temperature rise at the tumor area can be expected with heating using a relatively low frequency but overheating and multiple hot‐spots (heating point) as in the case of conventional high‐frequency heating are not pro

ISSN:8756-6621    

DOI:10.1002/ecja.4410650708

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1982

数据来源: WILEY

摘要:

AbstractA feature of the spread‐spectrum multiple‐access communication system is that multiple users can simultaneously utilize a common frequency spectrum, and applications to vehicle and satellite communications are anticipated. A problem, however, is that several seconds are required to establish synchronization for the PN code used on the receiving side. To solve this problem, it is proposed that the information for synchronization be acquired using a surface acoustic wave matched filter, but this is difficult in multiple‐access communication owing to the restriction on the number of taps. A new code applicable to the spread‐spectrum multiple‐access communication system with direct spread scheme aimed at the communication of analog information is proposed. It is shown that the surface acoustic wave matched filter, which has fewer taps and is more practical, can be used to drastically decrease the time required for the establishment of synchr

ISSN:8756-6621    

DOI:10.1002/ecja.4410650709

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1982

数据来源: WILEY

摘要:

AbstractIn radio astronomy by a super‐synthesis array the element antennas are rearranged and the rotation of earth is also used. By such arrangement, the spatial frequency components of radio source distributions are measured and are subsequently Fourier transformed for radio photographs. Spatial frequency components detected are determined by the element arrangement. Therefore, the element arrangement is important for effective tive use of the array. This paper discusses the number of weighted holes, which is proposed as a criterion for evaluation of the characteristics of element arrangement. As a method for analysis, we use random number trial experiments by computer and show from the results that the number of weighted holes becomes a good indication of the peak sidelobe level under an appropriate condition. Further, we propose a method of optimizing the element arrangement using this evaluation criterion. Its usefulness is confirmed by a simulation of super‐synthe

ISSN:8756-6621    

DOI:10.1002/ecja.4410650710

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1982

数据来源: WILEY

摘要:

AbstractMonochromatic light‐emitting diodes of different sizes and colors are widely used as small display devices. However, diodes of different colors for commercial purposes are those having a combination of red light‐emitting pellets and green light‐emitting pellets. Such a combination involves problems of color uniformity and brightness degradation. Therefore, a single pellet which has different uniform colors was proposed several years ago, but it has not yet been marketed due to many technical difficulties. The authors succeeded in making a single pellet with a green light‐emitting part and a red light‐emitting part on both sides of a GaP substrate. By changing the current ratio of the current flowing through the device, different colors were attained. This paper deals with different technical problems associated with device fabrication and the solutions to these problems. Also, electrical and optical properties of the device are

ISSN:8756-6621    

DOI:10.1002/ecja.4410650711

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1982

数据来源: WILEY