Path coverage properties of randomly deployed sensors with finite data-transmission ranges

We analyze the path coverage properties of a sensor network, where numerous sensors are randomly deployed. We characterize the path coverage in terms of three metrics: fraction of coverage, probability of complete coverage, and probability of partial coverage. We derive the expressions for the three coverage metrics as functions of the sensor density, the sensing range of a sensor, and the data-transmission range of a sensor. Based on the derived expressions, we study the impact of the data-transmission range on the path coverage and show, for example, that a sensor should have a long data-transmission range in order to achieve high detectability of intruding objects (partial coverage probability of the trajectories of objects) with a modest sensor density.     

PREPARATION OF FUNCTIONAL MATERIALS BY BLENDING COPOLYESTERS WITH PVA AND METAL COMPLEX FORMATION OF POLYMER BLENDS

Copolysters having secodary and tertiaryamine salt groups in the main and side chains are preparedby chemoselective polymerization.These copolyesters aresoluble in a 10% aqueous solution of poly (vinyl alcohol)(PVA) at 90℃ and act as plasticizer in the blend filmscast from the solution.Only a glass transition temperature isobserved for all these blends indicating the formation ofcompatible blends from these polyesers with PVA.Theseblends exhibit manifold characteristics such as ionic conduc-tivity,complex formtion with metal ions,absorption ofmoisture and Color changes.The electric conductivity of thecopolyesters and blends is in the range of 10~(-6)Scm~(-1).Theblends with PVA forms complexes with Cu~(2 ) and Co~(2 ).The coordination structure with two chelate rings is suggst-ed for these polymer blend/metal complexes.     

Effects of Boron, Carbon, and Iron Content on the Stacking Fault Formation during Synthesis of β-SiC Particles in the System SiO2-C-H2

Through the systematic addition of B, C, and Fe, additive effects on the stacking fault formation and the morphology of the particles formed during reaction synthesis of β-SiC were investigated in the present study. The whisker content of the synthesized product and the formation mechanism of whiskers were closely related to the stacking fault density. The addition of B inhibited whisker formation probably because of isotropic imperfection and the suppression of surface diffusion. Increase in the reduction force by using an active carbon source and also adding excess carbon led to an increase in stacking fault density through enhanced whisker formation. In the presence of Fe, the synthesized β-SiC whiskers appeared to possess only a small amount of stacking faults. The growth mechanism was different with Fe; i.e., isotropic growth occurred via a dissolution-precipitation reaction through a liquid phase in the Fe-Si system.     

The effect of time and temperature on flexural creep and fatigue strength of a silica particle filled epoxy resin

Composite materials that use an epoxy resin as a matrix resins have superior mechanical properties over standard structural materials, but these materials exhibit time and temperature behavior when used for long periods and under high temperatures. This time and temperature behavior has not been fully explained. The purpose of this paper is to further describe this time and temperature behavior, increasing the reliability of this class of composite materials. The time and temperature dependence of flexural strength was examined by creep and fatigue testing. Flexural creep tests were carried out at various temperatures below the glass transition temperature. Flexural fatigue tests were carried out at various stress ratios, temperatures below the glass transition temperature and 2 frequencies. The time-temperature superposition principle held for the flexural creep strength of this material. A method to predict flexural creep strength based on the static strength master curve and the cumulative damage law is proposed. When the fatigue frequency was decreased while temperature and stress ratio are held constant the flexural fatigue strength decreases. The time-temperature superposition principle was also found to hold for the flexural fatigue strength with respect to frequency.     

Bioactivity and mechanical properties of CaSiO3/high-density polyethylene (HDPE) composites prepared by a new surface loading method of CaSiO3 powder

CaSiO₃/high-density polyethylene (HDPE) composites with flexibility and biocompatibility were prepared by a new surface loading method. CaSiO₃ powder was synthesized by coprecipitation method with heating at 1300 °C for 2 h. The obtained α-CaSiO₃ powder was sieved to 45-75 μm (sample M) and 75-150 μm (sample C). Fine powder sample (sample F) was prepared by grinding the powder being the average particle size of 2.9 μm. These powders were sprinkled on the melted HDPE sheets heated at 160, 180 and 200 °C. The amounts of sprinkled powder were only <0.1 vol.% but the ratios of surface coverage area were >50% in all the samples. Apatite formation in simulated body fluid (SBF) was observed by soaking for 5 days in sample F while within 1 day in samples M and C. The sample M retained flexible properties of HDPE together with excellent biocompatible properties.     

Angiotensin-I converting enzyme (ACE) inhibitory mechanism of tripeptides containing aromatic residues

Angiotensin-I converting enzyme (ACE) plays important roles in the regulation of blood pressure, and ACE inhibitory peptides in food materials have attracted attention for their antihypertensive function. In this study, the function of amino acids in ACE inhibitory tripeptides was clarified.     

Diffusive-Ballistic Heat Conduction of Carbon Nanotubes and Nanographene Ribbons

Investigations of diffusive-ballistic heat conduction of finite-length single- walled carbon nanotubes and nanographene ribbons at room temperature have been carried out by using non-equilibrium molecular dynamics simulations. The length dependences of the thermal conductivity reveal the variation of the balance between ballistic and diffusive heat conductions. For both systems, the profile indicates a significant contribution of the ballistic phonon transport even with a length of about a micrometer. Comparison of the length effects of single-walled carbon nanotubes and nanographene ribbons highlights the roles of phonon dispersions and the extent of phonon scattering on diffusive-ballistic heat conduction.     

Emissions of mercury and other trace elements from coal-fired power plants in Japan

To evaluate trace element emissions from modern coal-fired power plants into the atmospheric environment in Japan, trace elements in the coal used in electric utility boilers, stack concentrations, emission rates and emission ratios of coal-fired power plants, and proportions of trace elements in coal-fired power plants were studied. The elements were As, B, Be, Cd, Co, Cr, F, Hg, Mn, Ni, Pb, Sb, Se and V, which are designated in the Law of Pollutant Release and Transfer Register. The particulate trace elements were collected in an electrostatic precipitator and a wet desulfurization scrubber. Emissions into the atmosphere were lower than 1% of the quantity in coal, but the volatile trace elements showed somewhat higher emission ratios. For mercury, the mean concentration in coal was 0.045 ppm, the mean emission rate was 4.4 microg/kW h, and the mean emission ratio was 27%, the highest ratio among all elements in this study. The total annual emission of mercury from coal-fired power plants of the electric power industry in Japan was estimated to be 0.63 t/y. On the basis of these data, the atmospheric environment loads from a coal-fired power station were investigated. The calculation of stack gas dispersion showed that maximum annual mean ground level concentrations were in the order of 10(-2) to 10(-5) of the background concentrations, and that the adverse effect of the emissions from the coal-fired power station was small.     

Observation of magnetic domain structure in phase-separated manganites by lorentz electron microscopy

Magnetic domain structure in manganites was investigated by Lorentz electron microscopy, in order to understand some unusual physical properties, such as a colossal magnetoresistance (CMR) effect and a metal-to-insulator (MI) transition. In particular, we examined the spatial distribution of the charge/orbital ordered (CO/OO) insulator state and the ferromagnetic (FM) metallic state in phase-separated manganites, (La5/8-xPrx)Ca3/8MnO3 for x = 0.375, by obtaining both the dark-field and Lorentz images. We found an unusual coexistence of the CO/OO and FM metallic states with micrometer size below a MI transition temperature of 60 K. Our experimental findings provide direct evidence of the phase separation found in CMR manganites.