Injection molding of micro-porous titanium alloy with space holder technique

The powder space holder(PSH) and powder injection molding(PIM) methods have an industrial competitive advantage because they are capable of the net-shape production of micro-sized porous parts.In this study,micro-porous Ti6Al4V alloy(Ti64) parts were produced by the PSH-PIM process.Ti64 alloy powder and spherical polymethylmethacrylate(PMMA) particles were used as a space holder material.After molding,binder debinding was performed by thermal method under inert gas.Debinded samples were sintered at 1250oC for 60 min in a vacuum(10-4 Pa) .Metallographic studies were conducted to determine densification and the corresponding microstructural changes.The surface of sintered samples was examined by SEM.The compressive stress and elastic modulus of the micro-porous Ti64 samples were de-termined.The effects of fraction of PMMA on the properties of sintered micro-porous Ti64 alloy samples were investigated.It was shown that the fraction of PMMA could be controlled to affect the properties of the Ti alloy.     

Electrical characterization of MS and MIS structures on AlGaN/AlN/GaN heterostructures

The forward and reverse bias I-V, C-V, and G/ω-V characteristics of (Ni/Au) Schottky barrier diodes (SBDs) on the Al_0.22Ga_0.78N/AlN/GaN high-electron-mobility-transistor (HEMTs) without and with SiN_x insulator layer were measured at room temperature in order to investigate the effects of the insulator layer (SiN_x) on the main electrical parameters such as the ideality factor (n), zero-bias barrier height (Ф_B0), series resistance (R_s), interface-state density (N_ss). The energy density distribution profiles of the N_ss were obtained from the forward bias I-V characteristics by taking into account the voltage dependence of the effective barrier height (Ф_e) and ideality factor (n_V) of devices. In addition, the N_ss as a function of E_c-E_ss was determined from the low-high frequency capacitance methods. It was found that the values of N_ss and R_s in SBD HEMTs decreases with increasing insulator layer thickness.     

A novel field effect transistor with dielectric polymer gel

A novel organic-field effect transistor (OFET) has been fabricated. This device is original in the sense that it can be produced in ambient conditions with facile and cost-effective methods. Experimental results surprisingly revealed a high mobility value at the order of 0.38 cm²/Vs, and the gate voltage is also found to be lower than 1 V. The device exhibited excellent transistor characteristics at low voltages. Threshold voltage is around 0.26 V with 10³ on/off ratio. The device design is based on high effective capacitance value of a polymer gel, 1 μF, which is sandwiched between glass substrates on which source and drain electrodes were constructed.     

Palmtree: An IP alias resolution algorithm with linear probing complexity

Internet topology mapping studies utilize large scale topology maps to analyze various characteristics of the Internet. IP alias resolution, the task of mapping IP addresses to their corresponding routers, is an important task in building such topology maps. In this paper, we present a new probe-based IP alias resolution tool called palmtree. Palmtree can be used to complement the existing schemes in improving the overall success of alias resolution process during topology map construction. In addition, palmtree incurs a linear probing overhead to identify IP aliases. The experimental results obtained over Internet2 and GEANT networks as well as four major Internet Service Providers (ISPs) present quite promising results on the utility of palmtree in obtaining more accurate network topology maps.