Capacity of the WCDMA System Using High Altitude Platform Stations

In this paper, we provide a method to estimate the capacity of the wideband code division multiple access (WCDMA) scheme using High Altitude Platform Stations (HAPS), and demonstrate the results. This is to validate that the HAPS system is one of the most effective solutions to provide high quality wireless communication services, such as IMT-2000 services. We use a practical system model which describes the HAPS system most appropriately, and this leads to realistic estimation results. We estimate the reverse and forward link capacity of the HAPS WCDMA system and compare it to that of the terrestrial system. The estimation results show that the capacity of the HAPS WCDMA system is about 1.2–1.67 times larger than that of the terrestrial system.     

Volatile, Potential Attractants from Ripe Coffee Fruit for Female Mediterranean Fruit Fly

Twenty-eight volatile compounds from freshly crushed, ripe, dark red coffee fruit, Coffea arabica, were identified by dynamic headspace analysis techniques. Identifications were made on the basis of a comparison of Kovats indices and GC-MS spectra for unknowns and authentic samples. Of the compounds identified, 10 were alcohols, nine were aldehydes, five were ketones, and four were monoterpenes. The five most abundant volatiles in decreasing order were hexanal (21%), 2-(E)-hexenal (11%), 3-methyl-1-butanol (9.0%), 3-methyl-1-butanal (8.5%), and 1-hexanol (8.4%). The five least abundant volatiles of the 28 identified, in increasing order, were decanal (0.19%), methyl hexanoate (0.33%), pulegone (0.44%), α-isomenthone (0.45%), and 2-nonanone (0.55%). In preliminary tests, many of the identified volatiles attracted more female Mediterranean fruit flies than the control.     

DC and AC characteristics ofAL0.25Ga0.75As/GaAs quantum-well delta-dopedchannel FET grown by LP-MOCVD

Al_0.25Ga_0.75As/GaAs quantum well delta-doped channel FETs (QWDFETs) have been successfully fabricated by low-pressure metalorganic chemical vapor deposition (LP-MOCVD). The FETs with a gate dimension of 1.8 μm×100 μm had a maximum extrinsic transconductance of 190 mS/mm and a maximum current density of 425 mA/mm. The device showed extremely broad transconductances around its peak. The S-parameter measurements indicated that the current gain and power gain cutoff frequencies of the device were 7 and 15 GHz, respectively. The transconductance versus gate voltage profiles showed a plateau region through a range of 1.7 V supporting spatial confinement of the electrons. These values are among the best reported for delta-doped GaAs-based FETs with a similar device geometry     

A study of the interaction of atomic oxygen with various carbonaceous materials

A variety of techniques have been used to examine the manner by which atomic oxygen species interact with various carbonaceous solids. In addition, the effect of such a treatment on the physical and surface chemical properties of the carbons has been determined. In situ electron microscopy studies have enabled us to establish that graphite is probably the most reactive form of carbon for this reaction. This behavior is rationalized according to the notion that atomic oxygen reacts preferentially with the delocalized π electrons in the graphite basal plane to create micro-pits. It is shown that careful control of the reaction of atomic oxygen with a carbonaceous surface can lead to certain beneficial effects when such structures are used in a reinforcement application.     

The thermal environment in an earth-sheltered home in Korea

A number of Korea's climatological, geographical and social features make earth-sheltered construction an attractive option. This paper compares the thermal performance of an earth-sheltered house (specially designed to accommodate the conditions in Korea) with the thermal performance of a conventional residence. The researchers conclude that, except for the high humidity levels in the earth-sheltered house, the thermal environment of the earth-sheltered house is superior to that of the conventional residence. In light of these findings, the authors recommend that research be aimed at improving waterproofing and condensation control measures in earth-sheltered houses.     

Multi-objective genetic algorithm in reliability-based design optimization with sequential statistical modeling: an application to design of engine mounting

Structural and Multidisciplinary Optimization - The present study explores reliability-based design optimization (RBDO) using multi-objective genetic algorithm (MOGA) in the context of practical...