摘要:

AbstractProposed herein is a piecewise polynomial Galerkin approximation to invariant densities of 1‐dimensional nonlinear difference equationsxn+1= τ(xn) (n = 0,1…), in which map τ is an endmorphism of an interval I. The piecewise polynomial is a linear combination of N × K polynomial bases of degree K‐1; N is the number of partitioned subintervals of I. The approximate solution for K = 1 is shown to be identical to the Ulam‐Li solution. Forthermore, the sufficient condition for the L1convergence of the approximate solution (K = 2, 3) for large N is given. Numerical experiments demonstrate that the approximate solution for K = 3 produces a significant improvement of the Ulam

ISSN:8756-6621    

DOI:10.1002/ecja.4410650602

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

年代:1982

数据来源: WILEY

摘要:

AbstractIn this paper a heuristic graph coloring algorithm as applied to random graphs is analyzed theoretically. The result obtained by expanding on the results of [4] is presented first: letx1(n, cnδ−1) be the random variable representing a solution obtained by applying the algorithm to a randomn‐vertex graph having edges with probabilityp(n)=cnδ−(wherecis a constant and 1/2≪δ≦1). Also letx1(n, cnδ−1) be the random variable representing the chromatic number of the graph. Thenx1(n, cnδ−1)/x*(n, cnδ−1)≦(1+ϵ)2δ/(2δ−1)(pr.) holds. Here ϵ represents a value sufficiently smaller than 1. By contrast, it is important from the practical point of view to find an algorithm that is effective for an arbitrary randomn‐vertex graph. In this paper the above‐mentioned algorithm is evaluated using models withp(n)≪ It is found that this algorithm is effective for allnless thanN, w

ISSN:8756-6621    

DOI:10.1002/ecja.4410650603

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

年代:1982

数据来源: WILEY

摘要:

AbstractThis paper discusses the static multi‐object control problem for a distributed system in which more than one geographically distributed decision‐maker (control station) performs control based on their own object functions. The object function of the control station is given in an integral form, with the range of integration being limited to an interval which is of interest to the control station. Then the multi‐object control problem is formulated as an optimization problem for a vector functional, leading to the optimality condition. The paper further discusses the multi‐object decision problem to determine the unique optimal control input from the set of non‐inferior solutions of the multi‐object control problem. The problem is called the central decision problem, where there exists an upper‐level decision maker and his preferable solution is determined based on the global viewpoint and the central object function. The problem is called a set decision problem when such an upper‐level decision maker does not exist, and the solution preferable to the set members is selected for the benefit of the whole set. A method of solution with two steps is proposed using the restricted simplex method and internal point penalty method. The gradient method is used for numerical computation to optimize the system of partial differe

ISSN:8756-6621    

DOI:10.1002/ecja.4410650604

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

年代:1982

数据来源: WILEY

摘要:

AbstractThis paper proposes a method for reducing additive noise from noisy speech signal. The effectiveness of this comb filtering method is demonstrated via experiments. The method is applicable to noise with varying power and non‐flat spectrum. Listening experiments show that the proposed method improves the subjective S/N and the sound articulation of extremely noisy speech. Application of this method for the reduction of quantization noise and noise caused by bit error in PCM speech is investigated. Experimental results indicate that:(1)For error‐free 2‐to‐5 bit PCM the proposed method improves the subjective quality of the speech equivalent to one bit;.(2)For bit error rate ranging from 10−3to 10−1, the proposed method improves the quality of 8‐bit PCM speech equivalent to the reduction of error rate down to about 1/3∼1/5. It is very effective for reducing the quantization noise in 4‐bit PCM speech.(3)The proposed method is particularly useful for improving the sound articulation of extre

ISSN:8756-6621    

DOI:10.1002/ecja.4410650605

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

年代:1982

数据来源: WILEY

摘要:

AbstractThis paper describes the architecture of a hybrid switching network employing both circuit switching and packet switching. The network usually operates in a packet switching mode, but, depending on the traffic conditions, it can use special control packets to temporarily change certain lines to a circuit switching mode. The change between the two switching modes is performed dynamically depending on the traffic load of the network. Also described in this paper is the concept of metapacket which can be employed in some relatively small‐scale networks to average the load of packets and to reduce data transmission tim

ISSN:8756-6621    

DOI:10.1002/ecja.4410650606

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

年代:1982

数据来源: WILEY

摘要:

AbstractA new grating diplexer using dielectric waveguides is proposed for millimeter‐wave applications. It consists of two symmetric rectangular dielectric waveguides in which two 3‐dB hybrids and two gratings for band‐stop filters are contained. Hence, it is convenient for integration. In the analysis of grating structures, we introduce equivalent circuits to whichF, S, andTmatrices are applied to obtain the dispersion properties and the frequency characteristics of reflection and transmission. Experimental data obtained at millimeter‐wave frequencies agree well with theoretical values. It is found that millimeter‐wave grating diplexers can be used as bandsplitting diplexers and channel diplexers in millimeter‐wave communicatio

ISSN:8756-6621    

DOI:10.1002/ecja.4410650607

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

年代:1982

数据来源: WILEY

摘要:

AbstractThis paper describes miniaturization of a hybrid coupled diode phase shifter made of striplines and its widebanding. An impedance transformer setting the phase shift of a single‐bit phase shifter is fabricated with a coupled line with two open ends having a bias blocking capability. This makes the size of the phase shifter about one‐half of the conventional one. It is pointed out that a wideband characteristic of this phase shifter is possible by choosing a large ratio of the even‐mode impedance to the odd‐mode impedance in the coupled line. AnS‐band hybrid coupled phase shifter fabricated based on the present design method has a phase error less than 7.4 (RMS value) in the relative bandwidth of 26%, a loss of less than 1.4 dB and a VSWR of less

ISSN:8756-6621    

DOI:10.1002/ecja.4410650608

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

年代:1982

数据来源: WILEY

摘要:

AbstractEndless phase shifters in which phase angles up to 360° can be endlessly varied are required in such areas as space diversity. Conventional endless phase shifters are large in size because they employ waveguides. To make these phase shifters in an MIC form, this paper adopts a method in which the input signal is divided into two with a 90° phase difference and then vector‐combined with appropriate amplitude ratios. To reduce the loss caused by an MIC, we use the dual‐gate GaAs MESFET as an active element. Realization of an FET endless phase shifter requires a dual‐gate FET amplitude adjustment circuit with a small amount of phase shift for a second gate bias. A method of optimizing the second gate terminating impedance to minimize the phase shift has been experimentally studied, although no theoretical analysis is available to date. In this paper, we analyze an equivalent circuit including the bias dependence of the circuit parameters of the FET and numerically compute the amplitude and phase of a dual‐gate FET. The results are compared with those of experiments. It is found that a theoretical design of the second gate terminating impedance is possible. Finally, the results for a fabricated FET endless phase shifter are

ISSN:8756-6621    

DOI:10.1002/ecja.4410650609

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

年代:1982

数据来源: WILEY

摘要:

AbstractIt is important to develop a frequency synthesizer that does not require a sophisticated multiplier and which oscillates directly at the local oscillation frequency for use as a local oscillator, with a view to the simplification and miniaturization of a large‐capacity land mobile radio equipment. The mobile frequency synthesizer is required to have a high purity oscillation, fast channel‐switching and high stability when subjected to mechanical vibration. A 1000‐channel switchable type frequency synthesizer with direct oscillation and direct division at 800 MHz has been developed to satisfy these requirements, based on consideration of an 800 MHz voltage‐controlled oscillator of high purity and optimum circuit design of a phase synchronizer. This synthesizer consists of an 800 MHz voltage‐controlled oscillator, two synthesizer LSIs and a crystal oscillator. In comparison with the conventional 150 MHz frequency synthesizer, it is only 1/9 as large. This paper describes the design and performance of this 800 MHz frequency sy

ISSN:8756-6621    

DOI:10.1002/ecja.4410650610

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

年代:1982

数据来源: WILEY

摘要:

AbstractA traffic ontrol system using geographically distributed traffic databases is proposed. Each data base maintains nationwide network information such as the busy/idle statuses of customer lines and trunk groups.A local switching system accesses the regional database to process each outgoing call adequately. Each database periodically obtains local network information from all switching systems within the region of its coverage, transferring it to other data bases. Used in this system are, for example, satellite broadcast channels which update simultaneously the information stored in the data bases.For this traffic control system, (1) an acceptable time delay required to update the databases and to set up calls is obtained; (2) the effectiveness of this control system for dealing with focused overload is evaluated; and (3) loads on signaling channels, the satellite channel and the database system also are evaluated.

ISSN:8756-6621    

DOI:10.1002/ecja.4410650611

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

年代:1982

数据来源: WILEY