This development proposes a highly efficient air-conditioning airflow system for a computer-machine room having high-heat-generating equipment using forced-air cooling. The proposed system recirculates room air in the area surrounding equipment back to the cooling supply air supplied from a double floor. The recirculated air is therefore used as cooling air for computers. This system enables the blowing temperature difference of air-conditioner units to be increased, blower capacity to be decreased, and overall efficiency of air-conditioner units to be increased. Here, we have proposed an air-conditioning airflow system that decreases the amount of cooling supply air while ensuring adequate air ventilation for equipment using forced-air cooling, and a design method for achieving this system.

A switched nonlinear system is considered, and the interval between two consecutive switchings is assumed to be greater than a value called "the dwell time." When switching among nonlinear systems, using a constant dwell time generally fails to lead to stability. In this letter, a state dependent dwell time function with convergence guarantees is presented for discrete-time stable nonlinear systems.

As Internet access had spread, it has become an important potential means of lifeline communication. The Internet can fulfill a role in the everyday life of citizens by offering lifeline communication services such as the police, ambulance, gas, electricity, and water services when an emergency occurs. In these lifeline communications, a caller needs to be able to communicate with the nearby lifeline service in the same manner as on a PSTN (Public Switched Telephone Networks) without being consciously aware of the path the caller's message is taking. Moreover, the lifeline service agency must be able to acquire the caller's location and identity. However, it is very difficult to transfer these essential functions from the PSTN to the Internet without making significant changes, because of large differences between the PSTN and the Internet. In this paper, we discuss how to obtain these functions for lifeline communications in the Internet. We further propose a model and implement a lifeline communication system on the Internet.

The effects of air-intake format of forced-air-cooled equipment on the efficiency of air conditioning systems are studied. A modern data center features a large number of information-processing devices to provide telecommunication services. These devices generate considerable heat, and the equipment that houses these devices often employs "forced air cooling" in which a cooling effect is achieved by sucking in large amounts of room air. An air conditioning system used for a machine room filled with such equipment therefore requires high fan driving power resulting in significantly low air conditioning efficiency. In this study, we first performed mockup-based experiments to obtain a quantitative understanding of how different air-intake formats for equipment affect the temperature at various room locations such as equipment intake. We then created a model for predicting the temperature at various locations, and on the basis of this model, we analyzed the factors affecting intake temperature and examined how intake temperature affects air conditioning efficiency. It was found that placing air inlets in the lower 1/3 portion of forced-air-cooled equipment could prevent the equipment from reabsorbing the hot air that it blows out and therefore improve air conditioning efficiency.

A UPS with an energy storage function using long-cycle-life VRLA batteries has been developed. Combining the functions of UPS and energy storage is effective to enhance the cost-effectiveness of the UPS. New long-cycle-life VRLA batteries, with capacities of 1000 or 1500 Ah at 2 V, have been developed for the UPS. A cycle life of 3000 or more cycles was estimated from our cycle test. The UPS has been installed in a telecommunications building for field-testing. This paper describes the system configuration, electrical characteristics of the UPS and its components, and result of our field test.

In the formerly proposed theory for sub-linear (linear in a changed addition rule) systems, we developed a sub-linear mathematical theory and demonstrated its capability in several sub-linear systems. In this paper, we assert that we can further construct hybrid systems useful in engineering by combining sub-linear systems with linear systems, and as an example, we show the construction of a divergence-free electrodynamics. Since the energy of photon fields in engineering is tending upward, it would be desirable for us to get rid of the divergence difficulties encountered in the conventional high energy electrodynamics. The most important result is the recognition that Nature herself has a hybrid system composed of sub-linear photon fields and linear electron fields. Mathematically, our electrodynamics is formulated by only one point correction (the insertion of tanh into the electromagnetic energy density) in the conventional electrodynamics of photons and electrons (including positrons).

This report describes a concrete method for realizing adiabatic charging reversible logic. First, we investigate the stabilization properties of a charge recycle regenerator using a switched capacitor circuit by SPICE simulation and an analytical method. In the N-step case, we proved that a step waveform is spontaneously generated. Next, for combinational logic, we propose an adiabatic charging binary decision diagram logic gate (AC-BDD) that uses this regenerator. The AC-BDD uses pass transistor logic based on a BDD, which is suitable for adiabatic logic. 8-bit AC-BDD multipliers were fabricated, and it is clarified that power consumption is reduced to 15% that of the same-rule-designed CMOS at 1 V and 1 MHz. Finally, we propose clocked energy reversible logic (CERL) that maintains the CMOS architecture for CMOS compatibility. CERL can reduce the clocked energy, which is used for charging the clock load capacitance, to 10% that of CMOS by using a power clock from the charge recycle regenerator.

Energy consumption is one of the most critical constraints in the design of portable embedded systems. This paper describes an empirical study about the impacts of compiler optimizations on the energy consumption of the address bus between processor and instruction memory. Experiments using a number of real-world applications are presented, and the results show that transitions on the instruction address bus can be significantly reduced (by 85% on the average) by the compiler optimizations together with bus encoding.

This paper discusses stability boundaries in an electric power system with dc transmission based on a differential-algebraic equation (DAE) system. The DAE system is derived to analyze transient stability of the ac/dc power system: the differential equation represents the dynamics of the generator and the dc transmission, and the algebraic equation the active and reactive power relationship between the ac system and the dc transmission. In this paper complete characterization of stability boundaries of stable equilibrium points in the DAE system is derived based on an energy function for the associated singularly perturbed (SP) system. The obtained result completely describes global structures of the stability boundaries in solution space of the DAE system. In addition the characterization is confirmed via several numerical results with a stability boundary.

Broadcasting in wireless mobile computing environments is an effective technique to disseminate information to a massive number of clients equipped with powerful, battery operated devices. To conserve the usage of energy, which is scarce resource, the information to be broadcast must be organized so that the client can selectively tune in at the desired portion of the broadcast. In this letter, the power efficient behavior of a predeclaration-based transaction processing in mobile broadcast environments is examined. The analytical studies have been performed to observe the effectiveness of predeclaration-based transaction processing combined with selective tuning ability in mobile broadcast environments.

In this letter, we show the effects of the chip waveform selection on the detection performance of the energy detector in DS/SS communications. Three chip waveforms such as rectangular, half-sine and raised-cosine are examined as the DS/SS chip waveform. It is demonstrated that the partial-band detection can enhance the detection performance of the energy detector approximately 50-70% compared with the full-band detection. When the chip rate is identical, the raised-cosine waveform shows lower detection probability due to its wider spreading bandwidth. However, when the spreading bandwidth is identical, the rectangular waveform shows lower detection probability due to its lower partial-band energy factor.

We propose a new electric contact device that greatly improves arc discharge characteristics. Electric contact functions are divided into an energizing operation and a switching operation. A capacitor is connected in series to a contact for switching contact. Using two conventional relay contacts, no arc operation is confirmed for a 42 V/3 A break operation. Contact resistances are measured over many operations, and the surfaces of electrodes are observed. A chip capacitor is arranged at one side of the contact electrodes of a twin relay, confirming the possibility of miniaturization.

In this paper we propose a parallel composition based adaptive notch filter for eliminating sinusoidal signals whose frequencies are unknown. The proposed filter which is implemented using second order all-pass filter and a band-pass filter can achieve high convergence speed by using the output of an additional band-pass filter to update the coefficients of the notch filter. The high convergence speed of the proposed notch filter is obtained by reducing an effect that an updating term of coefficient for adaptation of a notch filter significantly increases when the notch frequency approaches the sinusoidal frequency. In this paper, we analyze such effect obtained by the additional band-pass filter. We also present an analysis of a convergence performance of cascaded system of the proposed notch filter for eliminating multiple sinusoids. Simulation results have shown the effectiveness of the proposed adaptive notch filter.

Many parallel applications involve different independent tasks with their own data. Using the MPMD model, programmers can have a modular view and simplified structure of the parallel programs. Although MPI supports both SPMD and MPMD models for programming, MPI libraries do not provide an efficient way for task communication for the MPMD model. We have developed a programming environment, called ClusterGOP, for building and developing parallel applications. Based on the graph-oriented programming (GOP) model, ClusterGOP provides higher-level abstractions for message-passing parallel programming with the support of software tools for developing and running parallel applications. In this paper, we describe how ClusterGOP supports programming of MPMD parallel applications on top of MPI. We discuss the issues of implementing the MPMD model in ClusterGOP using MPI and evaluate the performance by using example applications.

The market for IP convergence services is expanding rapidly due to the rising number of Internet users. To respond to market trends, service systems must provide services quickly. This paper discusses that application server called the service agent which provides IP convergence services. The service agent meets the requirements for four application servers, centralized intelligence, supporting various interfaces: service creativity and scalability. The architecture is based on that of AIN systems, but whole system is written in Java especially to achieve service creativity and scalability. As a result of trial manufacture, feasibility of the service agent and scalability was achieved. Enough performance was also confirmed to obtain for commercial services.

This paper proposed a watermarking algorithm for image, which assumed an image compression based on DWT (Discrete Wavelet Transform). To reduce the amount of computation, this algorithm selects the watermarking positions by a threshold table which is statistically established from computing the energy correlation of the corresponding wavelet coefficients. The proposed algorithm can operate in a real-time if the image compression process operates in a real-time because the watermarking process was designed to operate in parallel with the compression process. Also it improves the property of losing the watermak and reducing the compresson ratio by the quantization and Huffman coding steps. It was done by considering the sign of the coefficients and the change in the value for watermarking. Visually recognizable pattern such as a binary image were used as the watermark. The experimental results showed that the proposed algorithm satisfied the properties of robustness and imperceptibility that are the major conditions of watermarking.

This letter deals with the common randomness problem formulated by Ahlswede and Csiszar. Especially, we consider their source-type models without wiretapper for ergodic sources, and clarify the secret key-capacity by using the bin coding technique proposed by Cover.

Many diverse methods have been developed in the field of biometric identification as a greater emphasis is placed on human-friendliness in the area of intelligent systems. One emerging method is the use of human footprint. However, in the previous research, there were some limitations resulting from the spatial resolution of sensors. One possible method to overcome this limitation is through the use additional information such as dynamic walking information in dynamic footprint. In this study, we suggest a new person recognition scheme based on overlapped foot shape and COP (Center Of Pressure) trajectory during one-step walking. And, we show the usefulness of the suggested method, obtaining a 98.6% recognition rate in our experiment with eleven people.

The high-end telecom terminal and PDAs, sometimes called Personal Trusted Devices (PTDs) are programmable, have tens of megabytes memory, and rather fast processors. In this paper we analyze, when it is energy-efficient to transfer application data compressed over the downlink and then decompress it at the terminal, or compress it first at the terminal and then send it compressed over up-link. These questions are meaningful in the context of usual application code or data and streams that are stored before presentation and require lossless compression methods to be used. We deduce an analytical model and assess the model parameters based on experiments in 2G (GSM) and 3G (FOMA) network. The results indicate that if the reduction through compression in size of the file to be downloaded is higher than ten per cent, energy is saved as compared to receiving the file uncompressed. For the upload case even two percent reduction in size is enough for energy savings at the terminal with the current transmission speeds and observed energy parameters. If time is saved using compressed files during transmission, then energy is certainly saved. From energy savings at the terminal we cannot deduce time savings, however. Energy and time consumed at the server for compression/decompression is considered negligible in this context and ignored. The same holds for the base stations and other fixed telecom infrastructure components.

A vibration-to-electric energy converter as a power generator through a variable-resonating capacitor is theoretically and experimentally demonstrated as a potential on-chip battery. The converter is constructed from three components: a mechanical-variable capacitor, a charge-transporter circuit and a timing-capture control circuit. An optimum design methodology is theoretically described to maximize the efficiency of the vibration-to-electric energy conversion. The energy-conversion efficiency is analyzed based on the following three factors: the mechanical-energy to electric-energy conversion loss, the parasitic elements loss in the charge-transporter circuit and the timing error in the timing-capture circuit. Through the mechanical-energy conversion analysis, the optimum condition for the resonance is found. The parasitic elements in the charge-transporter circuit and the timing management of the capture circuit dominate the output energy efficiency. These analyses enable the optimum design of the energy-conversion system. The converter is fabricated experimentally. The practical measured power is 0.12 µW, and the conversion efficiency is 21%. This efficiency is calculated from a 43% mechanical-energy conversion loss and a 63% charge-transportation loss. The timing-capture circuit is manually controlled in this experiment, so that the timing error is not considered in the efficiency. From our result, a new system LSI application with an embedded power source can be explored for the ubiquitous computing world.