An architecture framework for an adaptive extensible processor

To improve the performance of embedded processors, an effective technique is collapsing critical computation subgraphs as application-specific instruction set extensions and executing them on custom functional units. The problem with this approach is the immense cost and the long times required to design a new processor for each application. As a solution to this issue, we propose an adaptive extensible processor in which custom instructions (CIs) are generated and added after chip-fabrication. To support this feature, custom functional units are replaced by a reconfigurable matrix of functional units (FUs). A systematic quantitative approach is used for determining the appropriate structure of the reconfigurable functional unit (RFU). We also introduce an integrated framework for generating mappable CIs on the RFU. Using this architecture, performance is improved by up to 1.33, with an average improvement of 1.16, compared to a 4-issue in-order RISC processor. By partitioning the configuration memory, detecting similar/subset CIs and merging small CIs, the size of the configuration memory is reduced by 40%.     

Colored Fluorescent Silk Made by Transgenic Silkworms

Silk is a protein fiber used to weave fabrics and as a biomaterial in medical applications. Recently, genetically modified silks have been produced from transgenic silkworms. In the present study, transgenic silkworms for the mass production of three colors of fluorescent silks, (green, red, and orange) are generated using a vector originating from the fibroin H chain gene and a classical breeding method. The suitability of the recombinant silks for making fabrics is investigated by harvesting large amounts of the cocoons, obtained from rearing over 20 thousand silkworms. The application of low temperature and a weakly alkaline solution for cooking and reeling enables the production of silk fiber without loss of color. The maximum strain tolerated and Young's modulus of the fluorescent silks are similar to those of ordinary silk, although the maximum stress value of the recombinant silk is slightly lower than that of the control. Fabrics with fluorescent color are demonstrated using the recombinant silk, with the color persisting for over two years. The results indicate that large amounts of genetically modified silk can be made by transgenic silkworms, and the silk is applicable as functional silk fiber for making fabrics and for use in medical applications.     

Effect of GaAs surface pretreatment on electrical properties of MBE-ZnSe/GaAs substrate interfaces

Interface properties of MBE-grown ZnSe/GaAs substrate systems formed on variously pretreated GaAs surfaces, which include standard chemically etched (5H₂SO₄:1H₂O₂: 1H₂O), (NH₄)₂S_x-, NH₄I-, and HF-pretreated surfaces, are investigated by capacitance-voltage (C-V) and deep level transient spectroscopy (DLTS) measurements. A HF-pretreated and annealed ZnSe/p-GaAs sample showed marked reduction of interface state density, N_ss, with N_ss,_min below 4 x 10¹¹cm^-2 eV^-1 near E_c- E_FS= 1.0 eV. The value is about one order of magnitude smaller than that of the standard chemically etched interface, and comparable to (NH₄)₂S_x- pretreated interface. Nevertheless, C-V characteristics of ZnSe/nGaAs samples, which were measured for the first time, indicate that interface Fermi level, E_FS, is not completely unpinned due to the interface states located above the midgap. A consistent result was obtained by DLTS method in determining E_FS position. The influence of N_ss distribution on vertical current conduction is also analyzed. It is found that U-shaped interface states with N_ss(E) > 1 x 10¹³ cm^-2 eV^-1 above the midgap may cause an excess voltage drop larger than a few volts at the interface.     

Analysis of degradation in PEMFC caused by cell reversal during air starvation

The damage caused by cell reversal during proton exchange membrane fuel cells (PEMFCs) operation with air starvation was investigated by a single-cell experiment. Samples from degraded membrane–electrode assemblies (MEAs) were characterized. The loss of electrochemical surface area of the cathode platinum was detected by in situ cyclic voltammetry, and platinum sintering was detected by transmission electron microscopy (TEM) analysis. Degradation at the anode was not detected in the chemical analysis of the anode catalyst layer of MEA samples by energy dispersive X-ray analysis (EDX) and TEM. An obvious decrease in the performance of PEMFC was observed in a sample degraded by cell reversal for 120 min.     

Phase and amplitude comparison between experiment and calculation of ultrabroad-band pulses generated in a taper fiber

Using a cross-correlation frequency-resolved optical gating apparatus, the phases and amplitudes of ultrabroad-band optical pulses from a taper fiber have been measured for various input pulse peak powers. The measured waveforms have been compared with calculated waveforms using a finite-difference in the frequency domain method, in which no envelope approximations were used and the variation of the taper shape was taken into account. Excellent agreement between the measured and the calculated waveforms was obtained when the additional dispersion of a normal fiber and an objective was considered.     

The equivalent transmission-path model-a tool for analyzing errorfloor characteristics due to intersymbol interference in Nakagami-Ricefading environments

Land mobile radio systems such as car telephones and handy personal terminals used outdoors have enjoyed a remarkable evolution. To design reliable mobile radio systems, however, it is vital to have a good understanding of the impact of wave propagation characteristics on digital transmission quality in a wide variety of mobile radio environments. A very simple but general scheme for calculating irreducible bit error rate (BER) (namely, BER floor) due to intersymbol interference in frequency-selective Nakagami-Rice fading environments has been developed. The scheme, which we call the equivalent transmission-path model, plays a role in connecting wave propagation with digital transmission characteristics in a general manner. Through computer simulations assuming various types of delay profiles, we first identify key parameters of Nakagami-Rice fading dominating principally the occurrence of irreducible errors and we develop a simple method for the calculation of irreducible BER utilizing the nature or the key parameters. Then we examine the accuracy of the scheme for various types of phase-shift keying (PSK) transmission systems. Finally, based on the scheme, we show calculation examples of BER floor characteristics in line-of-sight fading environments     

SIR and SNR improvement in wideband beamspace array processing

Owing to limitations of frequency resources, advanced sensor array processing techniques are needed in a growing wireless wideband communications market. A beamspace wideband processing technique is proposed and is shown to reduce both signal to interference and SNR ratios. Performances for different array processing algorithms, flexibility and complexity cost are thus improved     

Analysis of availability improvement in LMSS by means of satellitediversity based on three-state propagation channel model

Aiming at future multimedia land mobile-satellite services (LMSS) consisting of a large number of nongeostationary Earth-orbit satellites, we present an LMSS propagation channel model for assessing the effect of a satellite diversity scheme so that high service availability and high signal quality are assured. We classify general fading environments for LMSS into three states. By taking the occurrence probability of each state into account, a new fading channel model is developed. The validity of the model is identified by comparing its predicted values in terms of the cumulative distribution function (CDF) with measured data available so far. Then, based on this model, we calculate the satellite diversity effect assuming that the area is illuminated simultaneously by at least two satellites moving in low Earth orbits (LEO) over urban and suburban environments. In addition, state transition characteristics based on a Markov model are presented     

3D computation of hydrogen-fueled combustion around turbine blade-effect of arrangement of injector holes-

Recently,a number of environmental problems caused from fossil fuel combustion have been focused on.Inaddition,with the eventual depletion of fossil energy resources,hydrogen gas is expected to be an alternativeenergy resource in the near future.It is characterized by high energy per unit weight,high reaction rate,widerange of flammability and the low emission property.On the other hand,many researches have been underway inseveral countries to improve a propulsion system for an advanced aircraft.The system is required to have higherpower,lighter weight and lower emissions than existing ones.In such a future propulsion system,hydrogen gaswould be one of the promising fuels for realizing the requirements.Considering these backgrounds,our group hasproposed a new cycle concept for hydrogen-fueled aircraft propulsion system.In the present study,we perform 3dimensional computations of turbulent flow fields with hydrogen-fueled combustion around a turbine blade.Themain objective is to clarify the influence of arrangement of hydrogen injector holes.Changing the chordwise andspanwise spacings of the holes,the 3 dimensional nature of the flow and thermal fields is numerically studied.     

Surface activity of the lipid products hydrolyzed with lipase and phospholipase A-2

We examined thein vitro surface activity, immersional wettability and adhesional wettability shown by aqueous solutions of soy lysophospholipid (SLP)/monoglyceride (MG)/fatty acid (FA), SLP/FA and SLP/MG, and found that many lipid mixtures showed significant surface activity when their MG and FA components consisted of polyunsaturated FA and/or medium chain FA. The more unsaturated the FA, the higher the surface activity. A mixture of SLP/medium chain fatty acid MG (medium chain MG)/medium chain FA showed the highest surface activity, and was comparable to an Aerosol-OT surfactant, the most effective wetting agent. SLP/polyunsaturated FA monoglyceride (polyunsaturated MG)/polyunsaturated FA, SLP/medium chain FA, and SLP/polyunsaturated FA, SLP/medium chain MG, and SLP/polyunsaturated MG also showed a high degree of activity. Wettability decreased rapidly when the amount of saturated, long chain FA moieties increased. It is recognized that the degrees of unsaturation and the chain length of FAs in the lipid mixtures have a decisive influence on surface activities. Higher ratios of MG and FA to SLP gave higher activity; and solubilizers such as bile salts were necessary to dissolve them in water.