Minimizing the guard time, Tguard, in the TCM-TDMA PDS scheme is essential in maximizing TCM transmission efficiency. As a replacement for the commonly adopted worst-case approach to TCM-TDMA PDS system estimation, this paper proposes a statistical approach. The level distributions of losses and n-th order Fresnel reflections are determined from published measurements. The proposed approach estimates the reflection of the optical access network.

The full liquid crystal display (LCD) simulation with real transistors and other active components is unrealistic. Because a flat panel display (FPD) includes thin-film-transistors (TFT's) whose number is, at least, the number of total pixels. It hits the simulation limit of SPICE if the number of transistors are more than 0.5 million. This paper demonstrates a new, fast, and effective simulation method for a full LCD panel. The method makes it possible to simulate large LCD panels whereas the conventional method cannot handle. The simulation circuit consists of a-Si TFT model presented earlier, the liquid crystal, the pixel macro models, and interconnects. We show the model parameter extraction and the pixel macro modeling process associated with the simulation results. Using the simulation method presented here some larger LCD panels can be accurately simulated in less than a minute on a workstation.

This paper discusses a new form of network database access with mobile agent technology, where many small database servers are distributed geographically, and are accessed through dial-up network on-demand. Coined "scattered database access" here, it enables such interesting ways of data access as asynchronous, circulatory, and the-more-you-spend-the-more-you-get kind of access. Databases to be accessed are relational databases, possibly from many different vendors, and PDM databases, also from several vendors. Relational databases, or RDBs, can be accessed by the SQL, an international standard that allows the interoperability of different RDB products in general. On the other hand, PDM databases, the data-stores for Product Data Management software, are not as inter-operable as RDBs, since the product-specific set of APIs has to be used to access them. An SQL-like language and a parser framework have been introduced to solve this problem. By implementing the parser as an object-oriented framework, the workload to adapt to many PDM products has been greatly reduced. The design and preliminary implementation has been carried out in a government-sponsored CALS project in Japan, and has been proven viable in the field, where a large steel-making company gathering information from many subordinate companies around the steel plant, and from other steel companies and equipment manufacturers.

Initial leveling of strapdown inertial navigation system is a prerequisite work for distinguishing between gravity and acceleration effects in the accelerometer sensing's. This study presents an on-line methodology to resolve the initial leveling problem of a vehicle, which is subject to a large, long duration, and abrupt disturbance input with a deterministic nature under noisy circumstances. The developed method herein is the Kalman filter based scheme with a robust input estimator, generalized M estimator, and a testing criterion. The generalized M estimator identifies the unexpected disturbance inputs in real time. In addition, hypothetical testing based on the least-squares estimator is devised to detect the input's onset and presence. A required regression equation between the observed value of the residual sequence with an unknown input and theoretical residual sequence of the Kalman filter with no input is formulated. Input estimation and detection are then provided on the basis of the derived regression equation. Moreover, Monte Carlo simulations are performed to assess the superior capabilities of the proposed method in term of rapid responses, accuracy, and robustness. The efficient initial leveling can facilitate the entire alignment of the inertial system.

In this study the spectral intensities of a breaking arc were measured near the cathode and the anode between separating Pd contacts in a DC 50 V/5 A circuit, and arc temperature and metal-vapor quantity and density were calculated. Results show the radial distribution of temperature in the cross section of an arc column was constant both near the cathode and the anode from the beginning to the extinction of the breaking arc. Near the cathode the arc temperature in the position of the peak value of spectral intensity rose to about 6000 K at the beginning and remained constant, but near the anode it rose to about 6000 K at the beginning and then decreased towards the extinction of the arc. Both near the cathode and the anode metal-vapor quantity and density rose suddenly at the beginning. Afterwards, they fell near the cathode until extinction. But they became constant approaching extinction near the anode. And the metal-vapor quantity was greater and the density higher near the cathode than near the anode.

Performance of optical asynchronous code-division multiple-access (CDMA) systems with double optical hard-limiters is analyzed in the presence of avalanche photodiode (APD) noise and thermal noise. Optical orthogonal codes (OOC's) are employed as signature sequence codes. In the analysis, chips are assumed to be synchronous among users: the chip synchronous case. Thus, the performance results in the upper bound on the performance of the asynchronous system. The results show that the optical asynchronous CDMA systems with double optical hard-limiters have good performance in the presence of the APD noise and the thermal noise even when the number of simultaneous users is large.

The alloy of Ag (40wt%)-Pd(60wt%) has been used in the electrical contacts of electromechanical devices due to its superior contact properties. There is currently, an increasing trend to decrease the size of electromechanical devices. However, it has been difficult to obtain a high contact force and the high restoring force of contacts, and these problems cause contact failures such as high contact resistance. In response to this problem, the alloy is overlaid with an Au layer which is not affected by oxide films. However, when the contacts are subjected to an unacceptable amount of mechanical shock, adhesion of the Au overlay occurs easily. In order to solve these difficulties, it can be proposed to cover the contact surface with high electric conductive oxide films. With this concept, the Au overlay should be unnecessary. In the present study, to reduce the high contact resistance of the Ag-Pd alloy contaminated with an oxide film, very small amounts of Mg and Cr were used in separate doping trials to the alloy. The improvement of contact resistance characteristics is the focus of the present study. Specimens of Ag (40wt%)-Pd(60wt%), Ag-Pd-Mg(0.1, 0.5 and 1.0wt%), and Ag-Pd-Cr(0.1 and 0.5wt%) were oxidized at elevated temperatures to accelerate the process of oxidation, and the growth kinetic law of oxide films grown on the surfaces were evaluated by ellipsometry. The effect of the oxide film on the contact resistance characteristics were then clarified. A marked improvement of the contact resistance caused by the oxide film was found for the Ag-Pd alloy with a Mg doping agent. However, for the Cr doping agent, a low contact resistance was not obtained as same as the Ag-Pd alloy itself.

Arc and contact resistance characteristics of Ag and Pd contacts were determined in several kinds of dielectric liquids, such as distilled water, methanol and n-hexane, under the inductive load condition. The experimental results showed that arc discharge types are dependent on dielectric liquids. A steady arc develops in air under this test condition. However, it was found that not the steady arc but the showering arc occurs in distilled water and methanol at a low load current. It was demonstrated that this phenomenon is caused by the high capacitance generated by the ambient dielectric liquid. Also, in almost all cases, the contact resistance behavior in dielectric liquids is satisfactory because metal spots remain on the contact surface. However, in n-hexane, the contact resistance tends to deteriorate, particularly for the Ag contact, with increasing load current. It seems that the deterioration of contact resistance is caused by carbon included in n-hexane.

On account of its superior electrical contact performance, Ag (40wt%)-Pd(60wt%) alloy has been widely used to the electrical contacts of electromechanical devices. However, regarding small devices, some important difficulties arise due to the small size such as the degradation of the contact resistance caused by the oxide film grown on the surface. To solve these problems, it was reported previously that doping Mg and Cr into the Ag-Pd alloy was tried to improve the oxide film. As a result, the oxide film grown on the Ag-Pd-Mg surface exhibited a remarkably low contact resistance. However, for the oxide film on Ag-Pd-Cr, no improvement of the contact resistance was observed. In this study, to clarify the cause of the low contact resistance for Ag-Pd-Mg, the effect of the doping with a third element on the composition and formation of the oxide film was analyzed using electron diffractometry, XPS and STM. As a result, Ag was found to be distributed on the outermost surface and inside the oxide film formed on Ag-Pd-Mg. However, Ag was not found on the surface of and inside the oxide film formed on Ag-Pd-Cr. Therefore, it was concluded that the presence of Ag on the surface of and inside the oxide film reduces the resistivity of the film.

In a DC 50 V/5 A circuit, the relationship between the number of breaking arcs and the spatial distribution of the spectral intensity of breaking arcs of long duration near the cathode in palladium contact were examined through substitution of the contact surfaces of three different shapes: flat and spherical (1 mm radius and 2 mm radius). Findings show the distribution of spectral intensity in Pd arcs to be influenced remarkably by the shape of contact surface and the number of breaking arcs. However, the temperature of Pd arcs was affected neither by the shape of contact surface nor by the number of breaking arcs. The metal-vapor quantity present differed for flat and spherical surface contacts; however, it was not affected by the radius of the curved contact surfaces or by the number of breaking arcs. Additionally, the longer the duration of the breaking arc, the more metal-vapor was presented in the beginning of the arc. Furthermore, arc tracks on contact surfaces were observed with microscopes, clarifying that the relationship between the area of the clouded white metal on the cathode and the shape of contact surface is the same as the relationship between the existent area of measured spectra and the shape of the contact surface.

This paper discusses a power save management method appropriate for the features of the fiber-optic access network based on Passive Double Star (PDS) topology, where PDS termination processing LSIs for the Optical Network Unit (ONU) operate intermittently and the usage rate is low at the residential customer. We developed PDS termination processing LSIs for the ONU, performed power management, and evaluated the degree of consumed power.

This paper discusses an ATM based access system for a broadband access network that provides flexible and cost effective multimedia services for mass consumption including households. The access system proposed herein uses ATM-PDS subscriber transmission technologies, thus enabling multiple users to share a single fiber resource while transmitting or receiving multimedia information within the broadband network. The system also has virtual channel concentration function by using the bearer connection control protocol being studied for VB5. 2 interface in the ITU-T. We show that the virtual channel concentration function reduces the access cost per user. We also discuss multiple QoS control methods in the system to provide multiple services efficiently. This paper evaluates two methods to handle ABR class and UBR class traffic: shared bandwidth with preferred ABR method, and guaranteed bandwidth with overriding method. The result indicates that when using the shared bandwidth with preferred ABR method for the access system, ABR throughput and UBR throughput per VC depend on the proportion of the number of ABR-VC connections to the total active VCs and on the each buffer size in the access system. And it is difficult to control ABR-VC and UBR-VC throughputs in the access network by using the shared bandwidth with preferred ABR method, which simple mechanism. With the guaranteed bandwidth with overriding method, while ABR-VC throughput and UBR-VC throughput also depend on the proportion of ABR-VCs to the total VCs and on the buffer size, it can offer the minimum guaranteed throughput to the UBR traffic. The result shows the method is effective for easy service provisioning.

The introduction of networks providing Internet-like services such as the Open Computer Network (OCN) by NTT and others like it will lead to higher level demands by users. For example, users will be asking for higher quality, greater functionality, and lower charges for high-speed, high-throughput data transfer. To respond effectively to the wishes of sophisticated and varied users, technological development must be pursued from the user's point of view. For this reason, research and development is being performed on middleware to open up network functions and make it possible for the user and network to cooperate with each other. This paper discusses the development of major technologies for achieving an enhanced internetworking that should become a catalyst for the future multimedia network, and presents a future vision for the network.

In this paper, we propose a novel algorithm for all-digital high speed symbol synchronization to be called the MBECM (Modified-Band Edge Component Maximization). The proposed algorithm has a structure based on the spectral line method. It simplifies and modifies the existing BECM algorithm to compensate for the timing offset caused by different phase characteristics of the BPF (band pass filter) at 1/2T and -1/2T. The algorithm is also independent of the carrier recovery and requires only two samples per symbol for its operation. Until now the timing detector's characteristics of the spectral line method including the M-BECM was not analyzed, particularly effect of the timing offset at convergence point. We analyze the timing detector's characteristics of the M-BECM and derive expressions for the timing detector's mean value (often called the S-curve) as a function of the normalized symbol-clock phase, the rolloff parameterand the bandwidth of the BPF. By using these expressions, the PDbias for eliminating the timing offset at an optimal convergence point are calculated. We also analyze and evaluate performance of the proposed algorithm in various ways such as jitter, timing detector output characteristics, etc. and suggest improvements. The proposed M-BECM is compared to the popular Gardner algorithm for high speed modem applications. The proposed algorithm has simpler structure than the Gardner algorithm and simulation results reveal that the proposed algorithm has better overall performance than the Gardner algorithm in narrow band.

Next generation hand-held devices must provide seamless connectivity while obeying stringent power and size constrains. In this paper we examine this issue from the point of view of the Network Interface (NI). We measure the power usage of two PDAs, the Apple Newton Messagepad and Sony Magic Link, and four NIs, the Metricom Ricochet Wireless Modem, the AT&T Wavelan operating at 915 MHz and 2.4 GHz, and the IBM Infrared Wireless LAN Adapter. These measurements clearly indicate that the power drained by the network interface constitutes a large fraction of the total power used by the PDA. We then examine two classes of optimizations that can be used to reduce network interface energy consumption on these divices: transport-level strategies and application-level strategies. Simulation experiments of transport-level strategies show that the dominant cost comes not from the number of packets sent or received by a particular transport protocol but the amount of time that the NI is in an active but idle state. Simulation experiments of application-level strategies that significant energy savings can be made with a minimum of user-visible latency.

In order to improve luminance and luminous efficiency of color ac plasma displays (PDPs), absorption characteristics of ultraviolet rays were investigated for dielectric materials from a viewpoint of protecting layer of ac PDPs. The double protecting layer of MgF2 and MgO is clarified to be excellent property to improve the optical performance of color ac PDPs. The double protecting layer of MgF2 and MgO was applied to the barrier-rib electrode color ac PDPs and resulted in high luminance and luminous efficiency of 1030 cd/m2 and 1.0lm/W, respectively.

A GaAs SPDT switch IC operating at a low power supply voltage of 2.7 V has been developed for use in 1.9 GHz band personal handy phone system (PHS). In combination with MESFETs with low on-resistance and high breakdown voltage, the switch IC adopts parallel-LC resonant circuits and utilizes both stacked FETs and an additional shunt capacitor at the receiver side in order to realize low insertion loss, high isolation and low distortion characteristics. An insertion loss of 0.55 dB and an isolation of 35.8 dB were obtained at 1.9 GHz. The IC also achieved an output power of 25.0 dBm at 1 dB gain compression point, a second order distortion of -54.3 dBc and an adjacent channel leakage power of -66 dBc at 600 kHz apart from 1.9 GHz at 19 dBm output power.

We describe the implementation of an iterative method with the goal of gaining a long vector length. The strategy for vectorization by means of multipoint stencils used for discretization of the partial differential equations is discussed. Numerical experiments show that the strategy that requires certain restrictions on the number of grid points in the x and y directions improves the performance on the vector supercomputer.

In logic programming or functional programming languages, data objects, such as terms and lists, are immutable. In a basic implementation of such language, updating one element of an aggregate (contiguous data structure, such as an array) involves making a new copy of the whole aggregate. However, such copying can be expensive, and can be avoided by using a destructive update. We introduce the concept of a wrapper which enables destructive operation on an immutable object. Based on this concept, we designed the reversible functor as a solution to the aggregate update problem. We implemented the reversible functor in the existing SB-Prolog system and carried out several benchmarks. These benchmark results show its effectiveness. When using a large functor and updating it many times, the performance is improved dramatically by implementing the reversible functor. It incurs some overhead at runtime, but the amount is small and acceptable.

In this work is first presented that a PDLC film with a ferroelectric alignment layer realizes a bistable switching in similar to the surface-stabilised ferroelectric liquid crystal display devices. Such a bistability is found to critically depend on the squareness parameter of the ferroelectric layer as well as such material properties of the dispersed nematics as the elastic and the dielectric constants. It is also found that there exists an appropriate elastic constant to improve the optical transmittance. The dependence of the distribution of the radii of the nematic droplets on the electro-optic bistability is also investigated in detail by means of the numerical computations assuming a fractal distribution. The fundamental electro-optic properties of the presently, proposed PDLC cells imply the advantage beyond the conventional PDLC without any ferroelectric alignment layer.