In this paper, we analyze the multiple access interference of a variable processing gain DS/CDMA system and define discrete partial crosscorrelation functions. We also evaluate the bit error rate of the system using Gaussian approximation and bounding technique. Three kinds of spreading codes (long, short, and random codes) are considered in the analysis of the system. It is shown that the bit error rate of a user is not relevant to the processing gain of interfering users: it is relevant only to the processing gain of the user, transmitted powers, PN sequences, and spreading codes. The performance of short codes turns out to be better than that of long and random codes as in other systems.

The use of existing metallic local line facilities is being studied for the provision of high-speed digital transmission services. Local line characteristics have to be modeled in the form of the objective requirements that should be met by DSL for estimating the feasibility of the service provision in the actual network. This paper presents the results of a study that models the metallic media characteristics of NTT's local network. First, the line lenghts determined by the existing local line deployment rule and the cable types used in the networks are introduced. Second, the values of crosstalk characteristics, the most significant factors in limiting DSL range, are given by classifying essential line conditioning states of each cable. The values of crosstalk characteristics are newly computed by taking into account detailed cable pair-binding (cabling) structures, and the worst case values among all possible combinations of multiple inter-pair interfering-interfered relationships within a cable are given though a previous study approximated cable pair-binding structures. The crosstalk characteristics of NTT's and American local networks are also compared. A modified approximate equation of line propagation characteristics is also proposed for representative local lines, and its precision is verified by comparing simulation results to actual measurements in both frequency and time domains.

Micromachined sensors and actuators applied with electrostatic fields are getting widely developed. At the same time, "electrets," which are dielectrics carrying non-equilibrium permanent space charges or polarization distribution, are in demand because they improve the transducer characteristics. In this paper, we have reported on our successful fabrication of silicon dioxide electrets with extremely superior long-term charge stability by plasma chemical vapor deposition (PCVD). We have also reported on the correlation between the deposition conditions, the long-term charge stability and thermally stimulated current (TSC). Finally, the characterization of the long-term stable electrets will be described and discussed.

In-line transceiver chip emitting at 1.3 µm and receiving at 1.55 µm is described regarding the crosstalk occurring between the 1.3-µm laser and the 1.55-µm integrated photodiode. Contribution of optical and electrical crosstalk to the overall crosstalk is measured and discussed. Techniques to overcome the crosstalk are proposed and demonstrated by showing the feasibility of system compatible diplex sensitivities.

In this letter, a theoretical estimation of pick-up characteristics of the fiber probe of Photon Scanning Tunneling Microscopy based on the Wiener-Hopf technique taken account of the weakly guiding approximation are reported. As a result, it is found that diffracted waves by the extremity of the fiber probe mainly act on the mode excitation rather than transmitted waves, then the pick-up characteristics are well accordance with typical experiments quality and quantity.

With the scale-down of VLSI chip size and the reduction of switching time of logic gates, crosstalk faults become an important problem in testing of VLSI. For synchronous sequential circuits, the crosstalk pulses on data lines will be considered to be harmless, because they can be invalidated by a clocking phase. However, crosstalk pulses generated on clock lines or reset lines will cause an erroneous operation. In this work, we have analyzed a crosstalk fault scheme, and developed a fault simulator based on the scheme. Throughout this work, we considered the crosstalk fault as unexpected strong capacitive coupling between one data line and one clock line. Since we must consider timing in addition to a logic value, the unit delay model is used in our fault simulation. Our experiments on some benchmark circuits show that fault activation rates and fault detection rates vary widely depending on circuit characteristics. Fault detection rates of up to 80% are obtained from our simulation with test vectors generated at random.

This paper analyzed the connection points of Main Distribution Frames (MDF), which are installed between outside plants and inside plants (service nodes). This paper also proposes a connecting system for forthcoming FITL (Fiber In The Loop) networks. NTT has developed the Subscriber Line Cross-Connecting Module (LXM) for the FITL network and will continue to introduce LXMs and deploy optic subscriber networks in big cities throughout Japan.

We report on the formation technique and the first observation of visible light emission from silicon nanoparticles (<10nm) embedded in CaF22 Iayers grown on Si(111) substrates by using codeposition of Si and CaF2. It is shown that the size and density of silicon particles embedded in the CaF2 layer can be controlled by varying the substrate temperature and the evaporation rates of CaF2 and Si. The photoluminescence (PL) spectra of Si nanoparticles embedded in CaF2 thin films were investigated. The blue or green light emissions obtained using a He-Cd laser (λ=325nm) could be seen with the naked eye even at room temperature for the first time. It is shown that the PL intensity strongly depends on growth conditions such as the Si:CaF2 flux ratio and the growth temperature. The PL spectra were also changed by in situ annealing process. These phenomena can be explained qualitatively by the quantum size effect of Si nanoparticles embedded in CaF2 barriers.

It is well known that extracting parallel loops plays a significant role in designing parallelizing compilers. The execution efficiency of a loop is enhanced when the loop can be executed in parallel or partial parallel, like a DOALL or DOACROSS loop. This paper reports on the practical parallelism detector (PPD) that is implemented in PFPC (a portable FORTRAN parallelizing compiler running on OSF/1) at NCTU to concentrate on finding the parallelism available in loops. The PPD can extract the potential DOALL and DOACROSS loops in a program by invoking a combination of the ZIV test and the I test for verifying array subscripts. Furthermore, if DOACROSS loops are available, an optimization of synchronization statement is made. Experimental results show that PPD is more reliable and accurate than previous approaches.

Time-domain characteristics of the signal of an open-loop fiber optic gyroscope were analyzed. The waveform moments of the gyroscope signal were dependent upon the rotation-induced Sagnac phase, just as the signal frequency spectra are. The peak positions of the time signal also varied with the supplied rotation, and the Sagnac phase could be read out, with optimum sensitivity, from the intervals between peaks. To demonstrate the time-domain measurement technique, the gyroscope signal was transferred to lower frequencies and the signal period was lengthened. This equivalent-time scheme lowered the operational speed requirement on the signal processing electronics and improved measurement resolution.

In this paper, we present an analysis of microstrip line with a trapezoidal dielectric ridge in multilayered media. The method employed in this characterization is called partial-boundary element method (p-BEM) which provides an efficient technique to the analysis of the structures with multilayered media. To improve the convergence of the Green's function used in the analysis with the P-BEM, we employ a technique based on a combination of the Fourier series expansion and the method of images. Treatment on convergence for the boundary integrals is also described. After this treatment, it requires typically one tenth or one hundredth of Fourier terms to obtain the same accuracy compared with the original Green's function. Numerical results are presented for two microstrip lines that have a trapezoidal dielectric ridge placed on a one-layered substrate and a two-layered substrate. These numerical results demonstrate the effects on the characteristics of the microstrip line due to the existence of the dielectric ridge as well as the second layer between the ridge and the fundamental substrate.

Resonant properties of resistance shunted tunnel junctions have been investigated using the RLCSJ model. We found that an increase in dc current resulted from an increase in impedance of the shunted tunnel junctions. The static and dynamic properties of the shunted tunnel junctions were described in detail by numerical simulations and experiments. The simulated and measured results showed good agreement in I-V characteristics. A Josephson array oscillator has been proposed using the resonant properties for increasing oscillator output impedance. We designed and fabricated the oscillator with 20 shunted tunnel junctions. The output power of the oscillator delivered to the load resistor was estimated to be about 0.5µW at 312 GHz.

In this study, we analyze the system which simultaneously transmits spread-spectrum signals with different processing gains. The main purpose of this study is to give an analytical framework that describes the influence of the interfering signals with different processing gains. For this purpose, we define a crosscorrelation function between the spreading sequences with different code lengths, and discuss the effects of interaction between the signals. As the results, we show that the power of the interference component after despreading procedure, the power ratio of the desired to undesired components, and thus the bit error rate are not constant but vary symbol by symbol.

This paper presents a configuration of circularly polarized annular-ring microstrip antenna (ARMSA) and its design method to obtain high gain and low axial ratio including the analysis of finite ground plane effect using G.T.D. for personal satellite communication use. The ARMSA excited at TM21 mode through co-planar branch-line hybrid coupler for circular polarization produces a conical pattern which has high gain in low elevation angle. The relation of gain and axial ratio versus the dielectric constant of substrate are shown and the existence of the dielectric constant which satisfies two requirements, that is, high gain and low axial ratio are clarified. For car-top application, experimental results in the L-band showed satisfactory characteristics for vehicle antenna.

The recent advance of semiconductor technologies enable to produce a medium size of crossbar with reasonable cost. By making the best use of the high bandwidth of such crossbars, indirect networks including the base-m n-cube and HyperCross have been proposed and researched. In these networks, a node is connected other nodes through crossbars in multiple dimensions. Although these networks are practically used in commercial machines, almost no discussion on a class of networks including them has been done. In this paper, a network class called Multi-Dimensional X'bar (MDX) which includes the above two networks is defined. Several new networks in this class are proposed, and relationship between these networks and direct networks/multistage interconnection networks is discussed. Finally, routing methods for these new networks are proposed and the average distance is evaluated. Through the discussion and evaluation, the MDX supports higher bandwidth than the corresponding multistage interconnection network with smaller hardware than the corresponding direct network.

Either GMW sequence or m-sequence possesses a 2-valued auto-correlation function which helps to improve the performance of a RAKE receiver. However, their cross-correlation functions are less well controlled. Before they can be applied to a CDMA system, it is necessary to construct their sub-families (taking advantage of their large family size) which offer satisfactory cross-correlation functions. This paper studies several algorithms for constructing those quasi-optimum sub-families in terms of minimized bit error rate under co-channel interference. The study shows that the performance of resultant sub-families is sensitive to sub-family sizes and algorithms. A new criterion based on combined (even and odd) maximum cross-correlation for code selection is introduced, and highest-peak-deleting and most-peak-deleting algorithms are suggested for constructing quasi-optimum sub-families of GMW and m-sequences.

A cavity model well suited for computed-aided design is developed to synthesize the dimensions of patches for a given resonant frequency, an input resistance and a substrate. The antennas which have been investigated are rectangular patches fed with either a microstripline or a coaxial probe.

We proposed a new thchnique using saw wave modulation light to measure the thermal diffusivity of a transparent adhesive by photoacoustic microscope. In this technique, the time required for the measurement of it can be reduced by one-fifth compared with that of a conventional method.

The E-polarized plane wave diffraction by a perfectly conducting strip located at the plane interface between two different media is analyzed by the Wiener-Hopf technique. Applying the boundary conditions to the integral representations for the unknown scattered field, the problem is formulated in terms of the modified Wiener-Hopf equation(MWHE), which is reduced to a pair of simultaneous integral equations via the factorization and decomposition procedure. The integral equations are solved asymptotically for large strip width via the method of successive approximations leading to the first, second and third order solutions, which are valid at high frequencies. The scattered far field expression is derived by taking the inverse Fourier transform and applying the saddle point method. It is shown that the high-frequency scattered far field comprises the geometrical optics field, the singly, doubly and triply diffracted fields and the lateral waves. Numerical examples of the radar cross section(RCS) and the lateral waves are presented, and the far field scattering characteristics discussed in detail.

The charge neutralized at a small gap discharge has been evaluated from measured electromagnetic fields by two methods. The small gap discharges simulate ESD events. The evaluated charge decreases rapidly as a step shape immediately in a moment of the discharge. The accumulated static charge and the risetime of the neutralization step increase with the gap length. When the gap length is 0.1mm, risetime and the initial static charge are about 0.3ns and 5.6nC, respectively.