摘要:

AbstractThe analysis is made for hard‐mode instability in the Hodgkin‐Huxley model (H‐H model) axon and fluctuations near instability points under the current‐clamp condition. When stimulating currents reach 9.8 μA/cm2, the steady‐state solutions of the Hodgkin‐Huxley equation become unstable and stable limit cycles appear. The fluctuation at a certain frequency is greatly enhanced near instability points due to an increase of irreversible circulation of the fluctuation. The membrane impedance shows a sharp peak in this region. In the H‐H model, circulation equilibrium is maintained below instability points. For I = 9.8 μA/cm2, hard‐mode instability occurs due to increasing fluctuation of a certain oscillation mode caused by sharp frequency responses of the system. This result can explain qualitatively the critical slowing‐down phenomenon and a sharp peak in fluctuation spectrum obse

ISSN:8756-6621    

DOI:10.1002/ecja.4410640402

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

年代:1981

数据来源: WILEY

摘要:

AbstractA variable network is a network in which a designated input‐output characteristic can be obtained continuously by varying continuously a specific parameter. This paper describes two methods of approximating the desired variable characteristics by a rational transfer function and constructing it as a concrete network. In the conventional method, an approximation with good accuracy is obtained by raising the orders of the complex frequency s and the variable parameter λ. The actual construction of the network becomes difficult because of the higher orders. Two methods are proposed in this paper to avoid this difficulty. In the first method, the approximated transfer function is divided into unit blocks, lower order for the complex frequency s and a bilinear form for the variable parameter λ. By this method, the actual construction of a network can be simplified considerably. In the second method, the desired characteristics are approximated in the form of a transfer function in which the denominator polynomial is resolved into the polynomials of s and λ, respectively. The approximated transfer function in this form has a merit in that it can be realized with a minimal number of dynamic elements and variable elements in the network construction. Moreover, its stability is independent

ISSN:8756-6621    

DOI:10.1002/ecja.4410640403

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

年代:1981

数据来源: WILEY

摘要:

AbstractIn transmitting and storing signals and images, the information content of the signals and images must be compressed using sampling and quantization techniques. This paper examines a generalization of the sampling theorem permitting a realistic observation window and proposes a new inverse quantization method suitable for this generalized sampling and usual quantization.

ISSN:8756-6621    

DOI:10.1002/ecja.4410640404

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

年代:1981

数据来源: WILEY

摘要:

AbstractThis paper deals principally with the phenomenological description and structural analysis of the signal flow of a nonuniform transmission line and presents a theoretical discussion, including the traditional theories, of the uniform transmission line. Due to the existence of local multiple reflections caused by nonuniformity, the phenomena on the nonuniform transmission line cannot be as clearly described as in the case of the uniform transmission line. The reason for existence of the local multiple reflections, however, is the lack of appropriate selection of the incident and reflected waves from the solutions of the transmission line equation. From such a viewpoint, this paper newly defines the incident and reflected waves as waves obtained by exciting a semiinfinite transmission line in the positive or negative direction. According to this definition, the two waves are not coupled and do not produce the local multiple reflections due to the nonuniformity. Thus, using such incident and reflected waves, a unified analysis can be made for the transmission line, independently of whether it is uniform or nonuniform. At the same time, the signal‐flow structure for such phenomena as reflection, matching and resonance can clearly be described. Using the concept of signal flow, the ultimate expressions for various quantities can easily be reache

ISSN:8756-6621    

DOI:10.1002/ecja.4410640405

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

年代:1981

数据来源: WILEY

摘要:

AbstractThis paper discusses the relation between the diameter and the number of nodes of a regular graph; also discussed is the relation between a regular graph with minimum diameter and minimal d‐connectivity from the viewpoint of graph theory for the construction of a communication network with high reliability and quality of communication.First, it is shown that the upper bound of the number of nodes n for given diameter k is Nk−2 in almost all cases, where Nkis Moore's upper bound. Second, it is derived that a regular graph with diameter k and degree d is minimal d‐connected when k ≧ 3 and Nk−d ≦ n

ISSN:8756-6621    

DOI:10.1002/ecja.4410640406

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

年代:1981

数据来源: WILEY

摘要:

AbstractThis paper describes a method for designing backfeed‐type one‐point fed circularly polarized antennas. These antennas are fed at one point from the back side of the substrate and have degeneracy‐resolving segments. Characteristics of the rectangular microstrip antennas with degeneracy‐resolving segments are obtained by means of a variational method. The equivalent circuit at and near the resonance with perturbations is obtained and the condition for circularly polarized antennas is found from both theoretical and experimental viewpoints. Configurations and radiation characteristics of these antennas are discussed and it is shown that these antennas can be used as array e

ISSN:8756-6621    

DOI:10.1002/ecja.4410640407

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

年代:1981

数据来源: WILEY

摘要:

AbstractSuper‐wideband amplifiers have become necessary in order to realize super‐highspeed digital transmission above 1 Gbit/s. In this paper a super‐wideband amplifier is realized based on a design method which makes practical use of the voltage gain and input impedence peaking effect due to the excessive phase shift of transistor. First, a single‐stage transistor unit amplifier is taken as a basic building block. These individual stages are then combined so as to simplify the design method. It is shown that the most suitable circuit for realizing wideband characteristics is that of voltage‐feedback unit amplifiers in cascade and with flattening circuits of parallelCRin the front. Also, from experiments using packaged bipolar transistor (fT= 10GHz), the characteristics of 4.3GHz high‐band cutoff frequency and 31 dB (6.2 dB per stage) a

ISSN:8756-6621    

DOI:10.1002/ecja.4410640408

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

年代:1981

数据来源: WILEY

摘要:

AbstractIn the past, variable length DPCM coding of gray scale image utilized block coding such as Hoffman coding scheme. However, if the midriser quantizer is used, the two levels close to zero level will occur with high probability. In such a case, the Huffman coding without extending the information source still results in a considerable level of redundancy. This is because the codewords can exist only at the tips of the branches of the coding‐tree, which is the constraint for the instantaneously decodable block code. This paper proposes a coding scheme which applies a technique similar to that used for transparency acquisition in the HDLC scheme, to insert a dummy bit into the non‐blocked codewords. In principle, it uses the properties of the bifix‐free pattern. When the two quantized levels close to zero occur with high probability, the proposed coding scheme yields a higher compression factor than does the Huffman code. Furthermore, the coding parameters can be varied adaptively depending on the properties of the image. Both the theoretical aspect of the proposed scheme and the simulation based on the standard test images are discussed in this

ISSN:8756-6621    

DOI:10.1002/ecja.4410640409

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

年代:1981

数据来源: WILEY

摘要:

AbstractRadiation characteristics of a balanced helical antenna with tapered open ends operating in both polarizations are described and compared with those of a balanced uniform helical antenna (UH). The effect of the taper which heretofore has been treated only experimentally, is evaluated numerically in detail. First, using an integral equation with a simplified kernel, we derive the current distributions on an arm with 4 to 10 turns of windings. Next, we calculate the radiation characteristics from the current distributions thus obtained. We find that variations of the axial ratio are small when the gain is almost equal to that of the UH. From the frequency characteristics over 2.6 to 4.5 GHz, we find that the suppression of the reflected current at the tapers is maintained over a wide bandwidth. From the theory and experiment, the fluctuation of the input impedance vs. the frequency is smaller than that in the UH. Due to the taper at the open ends, degradation of the axial ratio in the UH at high frequencies is removed.

ISSN:8756-6621    

DOI:10.1002/ecja.4410640410

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

年代:1981

数据来源: WILEY

摘要:

AbstractThis paper deals with an injection‐looking amplifier with opposite phase self‐injection circuit to which a part of the microwave oscillation output is injected by reflection with proper time delay and opposite phase to the oscillator. The amplifier characteristics are compared with those of the non‐self‐injection case under the oscillator load coupling state which gives maximum amplifier output. First, the optimum delay time of the opposite phase self‐injection circuit for different input and self‐injection conditions is obtained together with the static and phase responses, from which necessary basic data for self‐injection circuit construction are obtained. Next, one of the self‐injection circuits is shown and the characteristics of the amplifier with self‐injection circuit are investigated. Finally, the amplifier is tested and the phase response as a principal characteristic is investigated experimentally. Results show that the amplifier has fast phase response when the comparison is made under maximum

ISSN:8756-6621    

DOI:10.1002/ecja.4410640411

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

年代:1981

数据来源: WILEY