Simple approach to the mechanical anisotropy of cold-rolled zirconium alloys

The anisotropy for the mechanical properties of Zr was revisited using the developed modeling approach based on the physical constraints of the hexagonal close-packed lattice structure. The current approach successfully reproduced the anisotropy for the mechanical properties depending on the cold-rolling directions. It is suggested that the reversing behavior of the tensile strength and the yield strength with respect to the rolling and transverse directions is highly correlated with the structural characteristics of the hexagonal close-packed lattice.     

DSP-based active power filter with predictive current control

This paper presents an active power filter based on a digital signal processing (DSP) controller with enhanced current control performance. A novel predictive current control method is introduced to compensate the phase error of harmonic components caused by discrete sampling and finite nonnegligible execution time delay. The concept of average current control is also introduced that is adequate for digital current control. With a close coordination between the reference current prediction, PWM pattern generation, and control timing, a high performance control is achieved. Experimental results show that the developed system gives satisfactory performance in harmonic and reactive power compensation     

Channel width effect for organic thin film transistors using TIPS-pentacene employed as a dopant of poly-triarylamine

The effects of the physical channel width on the characteristics of organic thin film transistors (OTFTs), made with 6,13-bis(triisopropyl-silylethynyl)-pentacene (TIPS-pentacene) embedded into poly-triarylamine (PTAA, hole conductor within an active channel), have been examined in this paper. The devices are estimated by measuring the drain-source current (I_DS) for different contact metals such as Au and Ag, at fixed gate and drain voltages. The results show that the threshold voltage (V_T) and I_DS increase with increasing channel width. Furthermore, it has been observed that the field effect mobility is dependent on V_T, which is influenced by the channel width. The OTFTs, produced using Au and Ag contacts, exhibited the highest values of mobility in the saturation regime, namely 5.44 × 10^?2 and 1.33 × 10^?2 cm²/Vs, respectively.     

Influence of Aging Treatment on the Mechanical and Electrical Properties of Cu-0.5%Be Alloy

The influence of aging treatment on the microstructure,mechanical properties and electrical conductivity of Cu-0.5 wt pct Be alloy for connector material applications was investigated.The properties of mechanical strength and electrical conductivity increase with increasing aging temperature and time.Microstructure of the aged Cu-Be alloy revealed that grain size and fraction of low angle and high angle grain boundary were not greatly changed;however,transmission electron microscopy （TEM） analysis exhibited that beryllides precipitation （CoBe and NiBe） with a size of 50 nm were distributed in grains.It was,therefore concluded that these beryllide precipitates improved the mechanical strength and also it was favor in improvement of electrical conductivity.     

Heat conduction across monolayer and few-layer graphenes

We report the thermal conductance G of Au/Ti/graphene/SiO(2) interfaces (graphene layers 1 ≤ n ≤ 10) typical of graphene transistor contacts. We find G ≈ 25 MW m(-2) K(-1) at room temperature, four times smaller than the thermal conductance of a Au/Ti/SiO(2) interface, even when n = 1. We attribute this reduction to the thermal resistance of Au/Ti/graphene and graphene/SiO(2) interfaces acting in series. The temperature dependence of G from 50 ≤ T ≤ 500 K also indicates that heat is predominantly carried by phonons through these interfaces. Our findings suggest that metal contacts can limit not only electrical transport but also thermal dissipation from submicrometer graphene devices.     

Comparative analysis of phytochemicals and polar metabolites from colored sweet potato (Ipomoea batatas L.) tubers

Food Science and Biotechnology - We determined the phytochemical diversity, including carotenoids, flavonoids, anthocyanins, and phenolic acids, in sweet potatoes (Ipomoea batatas L.) with...     

Characteristics of A356/SiCp and A390/SiCp composites

Aluminum alloy matrix composites reinforced with SiC particles (AMC) are potential materials applicable to weight reduction of friction materials. We developed two AMC: A356/SiC and A390/SiC. 30 ??m and 60 ??m SiC particles with volume fraction of 20% were dispersed in the matrix of A356 and A390 alloys. When the temperature of the liquid alloy was higher than that of the melting point, SIC particles floated up to the surface because of the low viscosity, high surface tension and interfacial energy. To mix the ceramic particles, the aluminum alloy was in the mushy state near the solidus temperature, 610°C for A356 and 645°C for A390. Metallurgical, mechanical and tribological characteristics of the manufactured composites were evaluated.     

Nanoscale Joule heating, Peltier cooling and current crowding at graphene-metal contacts

The performance and scaling of graphene-based electronics is limited by the quality of contacts between the graphene and metal electrodes. However, the nature of graphene-metal contacts remains incompletely understood. Here, we use atomic force microscopy to measure the temperature distributions at the contacts of working graphene transistors with a spatial resolution of ~ 10 nm (refs 5-8), allowing us to identify the presence of Joule heating, current crowding and thermoelectric heating and cooling. Comparison with simulation enables extraction of the contact resistivity (150-200 Ω μm2) and transfer length (0.2-0.5 μm) in our devices; these generally limit performance and must be minimized. Our data indicate that thermoelectric effects account for up to one-third of the contact temperature changes, and that current crowding accounts for most of the remainder. Modelling predicts that the role of current crowding will diminish and the role of thermoelectric effects will increase as contacts improve.     

An improved PSF mapping method for EPI distortion correction in human brain at ultra high field (7T)

Object  

To further improve the quality and robustness of the point-spread function (PSF) mapping method for fully automatic and accurate correction of geometric distortions in EPI at ultra high field such as 7 Tesla with high fidelity.     

Microstructure and Mechanical Properties of Hyper-eutectic Al-Si Alloys Fabricated by Spray Casting

Microstructure and mechanical properties of hyper-eutectic Al-Si alloy fabricated by spray casting were in- vestigated and then these results were compared with those by squeeze cast.The spray-cast specimen was found to have finer Si particles （～5μm） compared to the squeeze-cast specimen （10-25μm）.The tensile strength and elongation of the spray-cast specimen are also higher than those of the squeeze cast one.It was considered that the increased mechanical properties of the spray-cast specimen were mainly due to finer size of the Si particles distributed in Al matrix.