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Scrutiny of Leakage Currents with Insulating Materials for Transistor Applications
Muhammad Sana Ullah,
Emadelden Fouad
Issue:
Volume 7, Issue 5, September 2018
Pages:
167-173
Received:
31 July 2018
Accepted:
27 August 2018
Published:
28 September 2018
Abstract: Continuous reducing the size of transistor technology has enabled extraordinary improvements in the switching speed, density, functionality and cost of microprocessors. Integrated Circuit industry is pursuing Moore’s curve down to deep-nanoscale dimensions. Advanced transistor technology now faces many challenges that together result in static power consumption due to leakage currents. In fact, leakage currents are responsible for more than 50% of the total power consumption in nanoscale designs. In deep-nanoscale arena, this percentage will increase further. However, diagnosing of the interface quality and interaction between insulators and semiconductors is significant to reduce the leakage current and achieve the high performance of switching devices in the nanoscale domain. Continuous scaling down has required drastic decreases of the SiO2 dielectric film thickness to achieve ever-higher capacitance densities. Fundamental limits of SiO2 as a dielectric material, imposed by electron tunneling, will be reached as this SiO2 film thickness approaches ~1nm. Therefore, alternate high-k interlayer dielectric material will be needed to replace SiO2 as a capacitor and gate dielectric material. Numerous alternate high-k materials are being actively investigated, ranging from Al2O3 (k ~ 9) to HfO2 (k ~ 25). High-k materials hold the promise of achieving very high capacitance densities with relatively thick films.
Abstract: Continuous reducing the size of transistor technology has enabled extraordinary improvements in the switching speed, density, functionality and cost of microprocessors. Integrated Circuit industry is pursuing Moore’s curve down to deep-nanoscale dimensions. Advanced transistor technology now faces many challenges that together result in static powe...
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Optimizing the Choice of Limestone Deposits for the Production of Portland Cement in Cameroon
Blaise Ngwem Bayiha,
Emmanuel Yamb,
Jordan Valdès Sontia Metekong,
Ndigui Billong,
Robert Nzengwa
Issue:
Volume 7, Issue 5, September 2018
Pages:
174-185
Received:
22 August 2018
Accepted:
10 September 2018
Published:
9 October 2018
Abstract: Despite the presence of raw materials (limestone and clay) deposits for Portland cement production, the major part of cement sold in Cameroon is from crushed imported clinker. This contributes to high cost of this material and reduction of local employment. In this study and based on existing data, a multi-criteria analysis tool was developed and applied to guide decision in the choice of limestone deposits in Cameroon for the production of Portland cement. The criteria evaluated were: calcium carbonate (CaCO3) content of limestone, proximity of the limestone deposit to a qualified clay source, estimate of its capacity, area covered by the limestone deposit, extraction of limestone easiness, accessibility to the limestone deposit and the proximity of the limestone deposit to a source of energy. The study is conducted on twelve limestone deposits identified by previous studies around the country. The PROMETHEE II methodology used made it possible to highlight the best deposits with respect to the criteria set. The results showed in terms of preference that, the Bidzar and Mintom deposits respectively in the North and South Regions are the two best deposits to be considered for the local production of Portland cement. Their exploitation will more promote purely local cement industry in Cameroon.
Abstract: Despite the presence of raw materials (limestone and clay) deposits for Portland cement production, the major part of cement sold in Cameroon is from crushed imported clinker. This contributes to high cost of this material and reduction of local employment. In this study and based on existing data, a multi-criteria analysis tool was developed and a...
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Effect of Physical Properties of Pr-Nd Oxide on Its Melton Salt Electrolysis
Wenyi Zhao,
Rongrong Fan,
Zhaoqiang Li,
Yan Wang,
Cheng Zhang,
Rong Wang,
Xin Guo,
Yu Wang,
Xuxia Zhang
Issue:
Volume 7, Issue 5, September 2018
Pages:
186-191
Received:
13 August 2018
Accepted:
28 August 2018
Published:
11 October 2018
Abstract: Industrial Pr-Nd oxide product has different physical properties, and shows different behaviors in the process of producing Pr-Nd metal by molten salt electrolytic. To meet the specific requirements of molten salt electrolysis for the physical properties of Pr-Nd oxide, different physical properties of raw materials such as particle size, specific surface area, morphology, bulk density and mobility were compared by chemical analogy experiment and actual production, the influence of physical properties of Pr-Nd oxide on its electrolysis process were studied, and the physical properties of the suitable electrolytic Pr-Nd oxide are quantified. The results show that particle size and morphology are the most important physical properties of Pr-Nd oxide in the electrolysis process. Pr-Nd oxide with good physical property requires the particle size is uniform and not too big or small. Additionally, the microstructure should not be over dispersed, but with agglomerate status, besides the micro surface should have porous structure to avoid melting phenomenon. The physical properties of raw materials produced by the method of oxalic acid precipitation are more stable than that by the ammonium bicarbonate precipitation method, and the good and stable physical properties are more suitable for molten salt electrolysis. So the oxalic acid precipitation method can be used as reference of the ammonium bicarbonate precipitation method.
Abstract: Industrial Pr-Nd oxide product has different physical properties, and shows different behaviors in the process of producing Pr-Nd metal by molten salt electrolytic. To meet the specific requirements of molten salt electrolysis for the physical properties of Pr-Nd oxide, different physical properties of raw materials such as particle size, specific ...
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Dynamic Characteristics of the End-effector of a Drilling Robot for Aviation
Ying Xu,
Qianfeng Wan,
Gang Lu,
Benshuang Zhang
Issue:
Volume 7, Issue 5, September 2018
Pages:
192-198
Received:
9 December 2018
Published:
11 December 2018
Abstract: This study discusses the dynamic stiffness of the End-effector of a drilling robot for aircraft. In view of the requirements of automatic drilling processing for aircraft parts, based on the analysis of the working process of the automatic drilling End-effector, the End-effector of drilling unit has been employed in precision machine tools, It can provide very smooth motion and good verticality. In the design of the machines, it is necessary to obtain the stiffness of these guideway. Therefore, an identification method of the guideway stiffness is verified in this paper. In this method, the guideway stiffness is identified from the natural frequency of the moving body. First, a virtual prototype of the End-effector of drilling unit flexible is constructed by jointly using both ANSYS, which provides a foundation for further dynamic characteristic simulations. Next, the impact test is carried out for a drilling tool to obtain the vibration mode of its moving body, and simple vibration model is developed based on the obtained vibration mode to identify the natural frequency of the guideways. For further verification, natural frequencies of the moving body are calculated by FEM with the identified natural frequency and compared with the measured natural frequencies. The results shows that : the natural frequencies were calculated almost correctly with the identified equivalent stiffness, and which provides theoretical reference for improving the drilling efficiency and assembly quality of aircraft components.
Abstract: This study discusses the dynamic stiffness of the End-effector of a drilling robot for aircraft. In view of the requirements of automatic drilling processing for aircraft parts, based on the analysis of the working process of the automatic drilling End-effector, the End-effector of drilling unit has been employed in precision machine tools, It can ...
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