Interference Reduction in Packet-Switched Time Division Duplexing Systems

In this paper, we propose two approaches to reduce interference in packet-switched TDD systems. The first involves the arranging of a judicious power margin between the BS and MS transmitters with and without power control. The second explores various slot assignment algorithms with and without slot reassignment. Significant improvements in performance can be obtained using such approaches, leading to gains in effective throughput.     

ZnS-based visible-blind UV detectors: Effects of isoelectronic traps

The aim of this study is to reveal the underlying cause of the gradual turn-on characteristic of low Te containing ZnSTe Schottky barrier photodiodes. The results of photoresponse studies on ZnS, ZnSSe and ZnSTe diodes indicate that the Te isoelectronic trapping effect is responsible for the gradual turn-on characteristic of low Te containing ZnSTe Schottky barrier photodiodes. The results also reveal that the ZnSSe diode, having the advantage of being free of isoelectronic centers, is a more suitable choice for applications requiring high visible rejection power. It is demonstrated that highly UV sensitive responsivity with an abrupt long wavelength cutoff tailored to lie between 340–400 nm can be achieved in the ZnSSe diode system.     

Simultaneous mobility: analytical framework,theorems and solutions

The original Mobile IP (MIP) protocol does not perform Route Optimisation but uses Home Agents to forward traffic. Thus, it does not have problems with simultaneous mobility, that is, the special case when both end hosts are mobile and move at about the same time. However, MIP for IPv6 (MIPv6) uses binding updates that are sent directly to a correspondent node. Session Initiation Protocol based mobility management (SIPMM) and MIP with location registers (MIP‐LR) also use direct binding updates between a mobile host and a correspondent node. Thus, MIPv6, MIP‐LR and SIPMM are vulnerable to the simultaneous mobility problem. In this paper, we analyse the simultaneous mobility problem and solution mechanisms, and propose new ways for MIPv6, MIP‐LR and SIPMM to handle simultaneous mobility. Copyright © 2006 John Wiley & Sons, Ltd.     

Effects of fiber composition and graft‐copoly(ethylene/maleic anhydride) on thermoplastic natural rubber composites reinforced by aramid fiber

Thermoplastic natural rubber (TPNR) composites of natural rubber and high‐density polyethylene at a ratio of 70/30 were prepared by melt blending with aramid fibers using an internal mixer. The fiber loadings were varied from 0 to 30% for systems with and without graft‐copoly(ethylene/maleic anhydride) (PE‐g‐MA) as a compatibilizer to study the variation of mechanical and dynamic mechanical properties. The tensile strength, modulus, hardness, and storage modulus improved with fiber loadings for both systems. The interaction between the matrix and fiber had also improved with the addition of PE‐g‐MA. Nevertheless, different behavior was observed in tan δ peak. The tan δ peak decreased with the increment of Twaron composition in the system with PE‐g‐MA and increased in the system without PE‐g‐MA. The results showed the importance of PE‐g‐MA in the system in improving the mechanical properties of Twaron–TPNR composite. POLYM. COMPOS., 27:395–401, 2006. © 2006 Society of Plastics Engineers     

Dead Zones in LX‐17 and PBX 9502

Pin and X‐ray corner turning data have been taken on ambient LX‐17 and PBX 9052, and the results are listed in tables as an aid to future modeling. The results have been modeled at 4 zones/mm with a reactive flow approach that varies the burn rate as a function of pressure. A single rate format is used to simulate failure and detonation in different pressure regimes. A pressure cut‐off must also be reached to initiate the burn. Corner turning and failure are modeled using an intermediate pressure rate region, and detonation occurs at high pressure. The TATB booster is also modeled using reactive flow, and X‐ray tomography is used to partition the ram‐pressed hemisphere into five different density regions. The model reasonably fits the bare corner turning experiment but predicts a smaller dead zone with steel confinement, in contradiction with experiment. The same model also calculates the confined and unconfined cylinder detonation velocities and predicts the failure of the unconfined cylinder at 3.75 mm radius. The PBX 9502 shows a smaller dead zone than LX‐17. An old experiment that showed a large apparent dead zone in Composition B was repeated with X‐ray transmission and no dead zone was seen. This confirms the idea that a variable burn rate is the key to modeling. The model also produces initiation delays, which are shorter than those found in time‐to‐detonation.     

Borate as a Phosphate Ester Mimic in Aldolase‐Catalyzed Reactions: Practical Synthesis of L‐Fructose and L‐Iminocyclitols

Dihydroxyacetone phosphate (DHAP)‐dependent aldolases have been widely used for the organic synthesis of unnatural sugars or derivatives. The practicality of using DHAP‐dependent aldolases is limited by their strict substrate specificity and the high cost and instability of DHAP. Here we report that the DHAP‐dependent aldolase L ‐rhamnulose 1‐phosphate aldolase (RhaD) accepts dihydroxyacetone (DHA) as a donor substrate in the presence of borate buffer, presumably by reversible in situ formation of DHA borate ester. The reaction appears to be irreversible, with the products thermodynamically trapped as borate complexes. We have applied this discovery to develop a practical one‐step synthesis of the non‐caloric sweetener L ‐fructose. L ‐Fructose was synthesized from racemic glyceraldehyde and DHA in the presence of RhaD and borate in 92 % yield on a gram scale. We also synthesized a series of L ‐iminocyclitols, which are potential glycosidase inhibitors, in only two steps.     

Stability study of PC power system

In this paper, the computer power system is studied from the point of view of system integration stability. The voltage regulator module (VRM) and silver-box are modeled and analyzed. The computer power system is unlikely to have stability problems based on today's structure, although there can be strong interactions between the VRM and silver-box in multiple VRM systems. Future trends of the PC power system are also analyzed. With power level increases, VRMs will have stronger interactions at lower frequencies. An example of conditional stability is shown to challenge the impedance stability criterion of integrated systems. Possible solutions to this problem are provided     

Quality adjusted life years (QALYs) and dose-response models in environmental health policy analysis -- methodological considerations.

Analyses of competing risks are currently limited by the lack of empirically well-founded and generalizable quantitative methods. Specifically, quantitative methods for comparative risk analysis require the consideration of the population impacted, the duration of impact, the health endpoints at risk, and the impact on individual quality of life. Whereas risk analysis can be used to provide quantitative estimates of disease incidence, environmental health policy analyses do not often account for differences in health impact from alternative disease states. We discuss the methodological issues related to the use of quality adjusted life years (QALY) as a metric for normalizing expected disease incidence to account for health impact. Through a case study of the risks and benefits of fish consumption, we demonstrate the use of QALY weights with dose-response models for environmental health policy decision making. We suggest that, although this approach can be generalized for use in comparative risk and health policy analysis, it is informationally intensive and requires additional assumptions to those used in traditional safety/risk assessment.     

A comparison of hot-gas by-pass and suction modulation method for partial load control in refrigerated shipping containers

Simulation studies using a mathematical model are made to compare the performance of the hot-gas by-pass control and the suction modulation control in refrigerated shipping containers. Key factors such as compressor power draw, coefficient of performance and the sensible heat factor of evaporator coil against variations in container load, set-point and ambient temperatures are examined. Results show that the suction modulation control strategy is the more energy efficient of the two. The evaporator performance is found to be largely unaffected by either strategy. The analysis indicates the possibility of controlling relative humidity in the cargo space by variation of the superheat level.