Plane harmonic waves in the theory of thermoviscoelastic materials with voids

In this article we analyze the behavior of plane harmonic waves in the entire space filled by a linear thermoviscoelastic material with voids. We take into account the effect of the thermal and viscous dissipation energies upon the corresponding waves and, consequently, we study the damped in time wave solutions. There are five basic waves in an isotropic and homogeneous thermoviscoelastic porous space. Two of them are shear waves, while the remaining three are dilatational waves. The shear waves are uncoupled, damped in time with decay rate depending only on the viscosity coefficients. The three dilatational waves are coupled and consist of a predominantly dilatational damped wave of Kelvin–Voigt viscoelasticity, other is predominantly a wave carrying a change in the void volume fraction and the third takes the form of a standing thermal wave whose amplitude decays exponentially with time. The explicit form of the dispersion equation is obtained in terms of the wave speed and the thermoviscoelastic homogeneous profile. Furthermore, we use numerical methods and computations to solve the secular equation for some special classes of thermoviscoelastic materials considered in literature.     

Transparent ceramics for high-energy laser systems

We demonstrate that transparent magnesium aluminate spinel ceramic possesses excellent thermo-optical properties, a record low absorption loss of 6 ppm/cm, and superior ruggedness which position it as a prime candidate for an exit window aperture for high energy laser systems, especially in hostile environments. We also demonstrate lasing with an efficiency of about 45% in transparent Yb³⁺:Y₂O₃ ceramic made by hot pressing high purity submicron co-precipitated powder. This paves the way forward for high power solid state lasers exploiting hosts with higher thermal conductivity than YAG.     

Is iron status associated with highly unsaturated fatty acid status among Canadian Arctic Inuit?

Impaired fatty acid synthesis was noted in iron deficient animal models. Human data, however, are scarce. Although Canadian Inuit have a traditional diet rich in heme iron and long chain n-3 fatty acids, recent literature has also indicated the presence of prevalent iron deficiency. We aimed to explore whether the presence of iron deficiency would affect fatty acid status and an estimate of the activity of desaturase 5 (Δ5), which is crucial in the biosynthesis of highly unsaturated n-3 fatty acids among Canadian Inuit. Erythrocyte membrane fatty acid composition was utilized as an indicator of fatty acid status and serum ferritin and circulating hemoglobin level were measured as the indicators of iron status. Data analyzed were collected among 1511 Canadian Inuit adult participants in the International Polar Year Inuit Health Survey, 2007-2008. Only 13.7% of survey participants had iron deficiency; however, serum ferritin showed a moderate positive association with highly unsaturated n-3 fatty acids after adjusting for age, waist and C-reactive protein (r = 0.172, P < .0001). Serum ferritin correlated significantly with Δ5 after further adjusting for highly unsaturated n-3 fatty acids (r = 0.126, P < .0001). Although the current study only demonstrated a weak link between ferritin and Δ5, the latter association underscores a possible health risk caused by a nutrient interaction related to reduced iron intake and decreased highly unsaturated n-3 fatty acid biosynthesis. Future studies are recommended to evaluate iron status in relation to highly unsaturated n-3 fatty acid biosynthesis and status among indigenous people undergoing rapid dietary transitions.     

5-GHz 32-bit integer execution core in 130-nm dual-V/sub T/ CMOS

A 32-bit integer execution core containing a Han-Carlson arithmetic-logic unit (ALU), an 8-entry /spl times/ 2 ALU instruction scheduler loop and a 32-entry /spl times/ 32-bit register file is described. In a 130 nm six-metal, dual-V/sub T/ CMOS technology, the 2.3 mm/sup 2/ prototype contains 160 K transistors. Measurements demonstrate capability for 5-GHz single-cycle integer execution at 25/spl deg/C. The single-ended, leakage-tolerant dynamic scheme used in the ALU and scheduler enables up to 9-wide ORs with 23% critical path speed improvement and 40% active leakage power reduction when compared to a conventional Kogge-Stone implementation. On-chip body-bias circuits provide additional performance improvement or leakage tolerance. Stack node preconditioning improves ALU performance by 10%. At 5 GHz, ALU power is 95 mW at 0.95 V and the register file consumes 172 mW at 1.37 V. The ALU performance is scalable to 6.5 GHz at 1.1 V and to 10 GHz at 1.7 V, 25/spl deg/C.     

INTERACTIVE SEMANTIC ANALYSIS OF TECHNICAL TEXTS

Sentence syntax is the basis for organizing semantic relations in TANKA, a project that aims to acquire knowledge from technical text. Other hallmarks include an absence of precoded domain-specific knowledge; significant use of public-domain generic linguistic information sources; involvement of the user as a judge and source of expertise; and learning from the meaning representations produced during processing. These elements shape the realization of the TANKA project: implementing a trainable text processing system to propose correct semantic interpretations to the user. A three-level model of sentence semantics, including a comprehensive Case system, provides the framework for TANKA's representations. Text is first processed by the DIPETT parser, which can handle a wide variety of unedited sentences. The semantic analysis module HAIKU then semi-automatically extracts semantic patterns from the parse trees and composes them into domain knowledge representations. HAIKU's dictionaries and main algorithm are described with the aid of examples and traces of user interaction. Encouraging experimental results are described and evaluated.     

Vitamin E inhibits fish oil-induced hyperlipidemia and tissue lipid peroxidation in hamsters

Previous research has linked hyperlipidemia with increased serum concentrations of lipid peroxidation products; however, a specific association between diet-induced oxidative stress and hyperlipidemia has not been studied. In the present study, the relationship between tissue lipid peroxidation and hyperlipidemia induced by ingestion of fish oil was examined. In Experiment 1, male Golden Syrian hamsters were fed semipurified diets composed of 1.6 wt% safflower oil plus 15.0 wt% of either butterfat (BF), safflower oil (SAFF), or high-cholesterol menhaden oil [MHO(H-CHOL)] semipurified diets for 27 d. The cholesterol contents of the diets were adjusted to 0.088%. The MHO(H-CHOL)-fed hamsters exhibited higher serum concentrations of total cholesterol, triglycerides, apolipoprotein B, and lipid peroxides when compared to the BF and SAFF diet groups. In a further study (Experiment 2), hamsters were fed for 27 d three dietary treatments: (i) MHO(H-CHOL) with no vitamin E content; (ii) a low-cholesterol menhaden oil containing high concentrations of vitamin E (2.5 mg tocopherol/g oil or dietary concentrations of 375 mg/kg) [MHO(L-CHOL)+E]; and (iii) the MHO(L-CHOL+E) with added cholesterol (595 mg/kg) [MHO(L-CHOL)+CHOL+E] to match the cholesterol content of the MHO(H-CHOL). The MHO(L-CHOL)+E and MHO(L-CHOL)+CHOL+E diet groups showed lower concentrations of serum cholesterol, triglycerides, and hepatic lipid peroxides than the MHO(H-CHOL)-treated group. Moreover, in contrast to the hypercholesterolemia caused by the MHO(H-CHOL) feeding, the MHO(L-CHOL)+E and MHO(L-CHOL)+CHOL+ E diets did not show a serum cholesterol-elevating action. This study supports the hypothesis that oxidative stress in the Syrian hamster could play a causal role in dietary-induced hyperlipidemia which can be inhibited by high vitamin E intake.     

高标清混合格式的广播世界

本将针对电视台从标清格式向标清与高清格式混合播出进行改造所需要考虑到的问题进行讨论。要想做到这一点就要找到满带宽基带运行模式与信号压缩模式的平衡点。     

Low-power encodings for global communication in CMOS VLSI

Technology trends and especially portable applications are adding a third dimension (power) to the previously two-dimensional (speed, area) VLSI design space. A large portion of power dissipation in high performance CMOS VLSI is due to the inherent difficulties in global communication at high rates and we propose several approaches to address the problem. These techniques can be generalized at different levels in the design process. Global communication typically involves driving large capacitive loads which inherently require significant power. However, by carefully choosing the data representation, or encoding, of these signals, the average and peak power dissipation can be minimized. Redundancy can be added in space (number of bus lines), time (number of cycles) and voltage (number of distinct amplitude levels). The proposed codes can be used on a class of terminated off-chip board-level buses with level signaling, or on tristate on-chip buses with level or transition signaling     

Analysis of dual-VT SRAM cells with full-swingsingle-ended bit line sensing for on-chip cache

This paper compares different high-V_T and dual-V_T design choices for a large on-chip cache with single-ended sensing in a 0.13 μm technology generation. The analysis shows that the best design is the one using a dual-V_T cell, with minimum channel length pass transistors, and low-V_T peripheral circuits. This dual-V_T circuit provides 20% performance gain with only 1.3× larger active leakage power, and 2.4% larger cell area compared to the best design using high-V_T cells with nonminimum channel length pass transistors     

Simulation of Concrete Paving Operations on Interstate-74

The objective of this paper was to study and optimize the concrete paving operations taking place in the reconstruction project of Interstate-74 using computer simulation. To achieve this objective, field data were collected during construction, and were then used to determine adequate probabilistic density functions for the activities’ duration and to test a developed simulation model. Upon testing, the developed model was used to study the impacts of resources on the flow of operations and on the cost effectiveness of the construction process. In general, application of simulation methods to concrete paving operations was successful and its accuracy was acceptable as compared to field measurements. Based on the results of a sensitivity analysis of the critical resources, multiple factors were considered in the decision-making process to ensure that all aspects of the operation are evaluated. This includes total operation time, productivity, costs of the operation, average truck delay, and idle times for the paver and the spreader. For the conditions pertinent to this construction site, ten trucks, one paver and one spreader, and three finishing and plastic-covering crews are recommended. Using this set of resources would result in a prompt and effective execution of the operation. Practical implementation and limitations of the developed model in similar construction operations is discussed.