摘要:

AbstractDevelopment of a method to measure the position and attitude of a tunneling machine is required for constructing a curved and long tunnel with a small diameter for communication cables. This paper presents a method to satisfy this requirement. Two coils (“send coils”) are set on the ground to generate an ac magnetic field. Another coil (“search coil”) to detect this magnetic field is set on the tunneling machine under use. This search coil rotates on orthogonal planes, one of which is parallel to the direction of the tunneling‐machine progression. The position and attitude of the machine are calculated from the voltage induced in the search coil. The direction of a component of the magnetic field at an arbitrary position (with reference to the send coils) is essential in this method; this was obtained from theoretical (the finite‐element method) and experimental values. Appropriate dimensions of the search coil were found by introducing “the height/width ratio” and “the winding ratio.” The detection accuracy of this method is about 20 cm on a horizontal plane, and about 2° in attitude, thereby confirmi

ISSN:8756-663X    

DOI:10.1002/ecjb.4420710301

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

年代:1988

数据来源: WILEY

摘要:

AbstractOptical pulse measuring instruments (OTDRs) are very useful in locating broken areas and assessing the homogeneity of optical fibers, etc. Until now, the theoretical relation between the measured results of the optical and splicing losses of cut‐back and OTDR methods was not known and OTDRs were not used to measure losses of steady‐state mode distributions. This study investigates the backscattering mode distribution of graded‐index optical fibers using geometrical optics. The launching condition of the light pulse and the receiving condition of back‐scattering, and their relation to the measured optical and splicing losses, are determined. The theoretical and experimental relation between the measured values of backscattering by OTDR and cut‐back methods is also discussed. As a result, it is shown that the steady‐state condition of the received backscattering light is necessary when measuring the losses of steady‐state mode distribution by OTDR method. We propose the possibility of estimating the splicing loss values of the cut‐back method from the difference of the splicing loss measurements under varied launching conditions of OTDR method. Correctness of this method is confirmed experimentally. In this method, no previous preparation is required and by changing the launching conditions at only one end, only two measurements are made and a simple calculation is required. Therefore, it is expected that measurement efforts are significantly reduced

ISSN:8756-663X    

DOI:10.1002/ecjb.4420710302

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

年代:1988

数据来源: WILEY

摘要:

AbstractIn this paper, the successive approximate method is used to treat the two‐mode loose coupled inhomogeneous systems where the propagation constants and coupling coefficients are functions of the propagation distance. That is, the successive approximate method is used to analyze in a general way the response of the system of coupled inhomogeneous equations. As a result, two or three comprising conditions are obtained for the devices to be used as mode transformers. To verify the correctness of the present method, the results are compared against those of the so‐called approximate integral method applied to the inhomogeneous systems in which only the coupling coefficients are varied with propagation distance. It is indicated that similar results are obtained. For example, in the case of the tapered lens medium, which has previously been treated from a wave point of view, no contradiction is observed. Finally, to demonstrate application of the present method, we use two‐mode directional couplers that are simple to construct and have only small l

ISSN:8756-663X    

DOI:10.1002/ecjb.4420710303

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

年代:1988

数据来源: WILEY

摘要:

AbstractThis paper proposes pre‐processing and matrix computation to improve the convergence, accuracy and computation speed required in the device simulator. In the pre‐conditioning, a method to increase the number of elements and Gustafsson's modification are employed. The result of application indicated that the element‐increasing method is more effective. In the solution of the problem represented by a symmetrical matrix derived from Poisson's equation, the element‐increasing incomplete Cholesky decomposition conjugate complex gradient method (ICCG (2, 4)) is seen to be suitable. Three methods to solve the problem represented by an asymmetrical matrix, which is derived from the current continuity, are examined; the ORTHOMIN method; the bi‐conjugate gradient method; and the CG‐square (CGS) method. From the viewpoint of the convergence and the computation time, the element‐increasing incomplete LU‐decomposition CGS method (ILUCGS (2, 4)) is seen to be the best. It is demonstrated that by those matrix manipulations, the convergence of the device simulator is improved, and a solution with a satisfactory accuracy is obtained in a short c

ISSN:8756-663X    

DOI:10.1002/ecjb.4420710304

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

年代:1988

数据来源: WILEY

摘要:

AbstractThe three‐phase three‐conductor transmission line can be used in an inductive radio system for detecting the position of a vehicle of a linear synchronous motor car. A quantitative investigation is developed on the relation between the crosstalk between positive and negative‐phase‐sequence components in a helically wound transmission line and deviations of the line conductors from their normal positions. The authors have derived the required accuracy in a manufacturing process of a line for the desired accuracy in detecting the vehicle position. Cases where line conductors deviate randomly from their normal positions and cases where there exist manufacturing imperfections similar to “asymmetrical twisting,” which occasionally happens in manufacturing “star quads” used in ordinary telephone cables, are analyzed. It is clarified that the position detection error is affected mainly by the near‐end crosstalk between positive and negative phase circuits, which is maximized when a vehicle approaches the nearest start terminal of the transmission line. Moreover, it is expected that the fairly satisfactory accuracy in the vehicle position detection is obtained if we can make the layout accuracy of line conductors within a few percent of the helical radius. The obtained results are expected to be applied analogously also to the flat‐type three‐phase

ISSN:8756-663X    

DOI:10.1002/ecjb.4420710305

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

年代:1988

数据来源: WILEY

摘要:

AbstractA single‐crystal thin‐film of 2‐methyl‐4‐nitroaniline (MNA), which is an organic compound with a very large optical nonlinearity was formed on a pyrex substrate. Using the structure as a waveguide, the phase‐matched second harmonic generation (SHG) of a YAG laser (wavelength 1.064 μm) was observed. The phase‐matching was achieved utilizing the TE mode phase‐dispersion of the guided wave. This is the first report where MNA thin‐film is used as a waveguide. The conversion efficiency for SHG is estimated as approximately 0.3 percent for the input power of 10 W, waveguide‐length of 2 mm and bea

ISSN:8756-663X    

DOI:10.1002/ecjb.4420710306

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

年代:1988

数据来源: WILEY

摘要:

AbstractA new NMR imaging method is proposed, where the data with contributions from the whole imaging area are examined, and the spin distribution image is reconstructed by computer processing. The method uses a weak scanning nonlinear gradient field which is an extension of the magnetic focusing method. The experimental result is described. It is shown that the detected signal is given by the Fresnel transform of the spin distribution, and a solution is obtained by a convolution integral. Based on the theory, imaging experiments were performed using a phantom, realizing a clear spin density distribution image. In the experiment, a magnetic field ofB0= 0.0192 Tesla was used, which is one order of magnitude weaker than the field in the usual NMR‐CT. The image was obtained with the resolution of approximately 1 mm by collecting the data for 32 s to 8 min. Some discussions are made on the spatial resolution of the method and the application to a large‐scale system, indicating that the method is highly promis

ISSN:8756-663X    

DOI:10.1002/ecjb.4420710307

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

年代:1988

数据来源: WILEY

摘要:

AbstractThis paper proposes a surface‐emitting‐type optical threshold device and analyzes its characteristics. For a surface‐emitting laser resonator with a saturable absorber, its static characteristics and small signal analysis with a current or light injection are obtained from rate equations. As a result, the possibility of an optical threshold device which operates with a practical optical energy of approximately 30 kW/cm2has been shown. Furthermore, it has been shown that the optical threshold varies by controlling an injection current, and that AND and OR logics are possible with one device. As a result of small signal analysis, the device is shown to have a bandwidth of approximately

ISSN:8756-663X    

DOI:10.1002/ecjb.4420710308

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

年代:1988

数据来源: WILEY

摘要:

AbstractThe output of the ISFET (Ion Sensitive Field Effect Transistor) was obtained as a voltage signal. To achieve the temperature compensation, a differential amplifier composed of ISFET and MOSFET was fabricated. For integration, the process and circuit designs for the ISFET and MOSFET were done carefully by considering both the device fabrication process and the electrical properties of the device. Polycrystalline silicon was used for the connection between the devices and the MOSFET gate electrode. The entire device surface was covered with Si3N4/SiO2to ensure the waterproof properties of the device. As a result, the MOSFET could be located near the ISFET and both FETs could be processed in the same manner. The fabricated ISFET could produce the voltage signal in accordance with the change in the gate membrane potential of the ISFET. The sensitivity of the device was 49 mV/pH. In addition, temperature compensation in the ISFET was achieved and the temperature coefficient was −0.8 mV/

ISSN:8756-663X    

DOI:10.1002/ecjb.4420710309

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

年代:1988

数据来源: WILEY

摘要:

AbstractThe collector‐top heterojunction transistor (C‐top HBT) with inverted structure is expected to operate at a much higher speed than the emitter‐top heterojunction transistor (E‐top HBT) because the former has a smaller base‐collector junction area. In this paper, the merits of the C‐top HBT compared to the E‐top HBT in circuit applications were investigated by the simulation of ring oscillation characteristics, including dependence on fan‐out and interconnect line length, and the divide‐by‐four circuit characteristics. The influences of the emitter, base and collector resistances and the external base capacitance of the HBT's on the switching characteristics, and the divide‐by‐four circuit performance were also investigated. The degree of improvement was evaluated, using results of simulation over HBT's with the reduced base resistance and the ex

ISSN:8756-663X    

DOI:10.1002/ecjb.4420710310

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

年代:1988

数据来源: WILEY