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91.
Chun Yang Yin Sharifah Aishah Syed Abdul KadirYing Pei Lim Sharifah Nawirah Syed-AriffinZurinawati Zamzuri 《Fuel Processing Technology》2008
Ash derived from combustion of Malaysian oil palm biomass (empty fruit bunches consisting of fibers) was physically and chemically characterized in order to provide a comprehensive understanding of its specific properties in terms of toxicity, compositions and reusability. Principal analyses conducted include particle size distribution, scanning electron microscopy, elemental dispersive X-ray, elemental analysis, toxicity characteristic leaching procedure (TCLP) as well as thermogravimetric, X-ray diffractometry and Fourier-transform infrared analyses. TCLP result indicated that the oil palm ash (OPA) should not be classified as toxic wastes in terms of heavy metal leachability since leachable copper, cadmium, lead and nickel concentrations were detected below the stipulated leachability limits. It was determined that the OPA contained high amount of potassium as well as presence of silica which implied its suitability to be reused as crude fertilizer or cement replacement material. 相似文献
92.
We present a numerical study of the packing of uniform spheres under three-dimensional vibration using the discrete element method (DEM), focusing on the effects of vibration condition (amplitude and frequency) and inter-particle frictions (sliding and rolling frictions). The results are analysed in terms of packing density, coordination number (CN), radial distribution function (RDF) and pore structure. It is shown that increasing either the vibration amplitude or frequency causes packing density to increase initially to a maximum and then decrease. Both vibration frequency and amplitude should be considered to characterize the effect of vibration process on packing structure. The sliding and rolling frictions between particles can decrease packing density since they dissipate energy, although the effect of rolling friction is less significant. In line with the change of packing density, microstructural properties such as CN, RDF and pore distribution also change: a looser packing often corresponds to smaller CN, less peaked RDF and larger but more widely distributed pores. 相似文献
93.
本文介绍了磁电机点火系统的点火提前角测量原理。对点火系统的点火信号和触发信号进行采集、调理,再用单片机进行处理,最后用LabVIEW进行点火提前角数据存储和显示。 相似文献
94.
Seyeong Choi Alouini M.-S. Qaraqe K.A. Hong-Chuan Yang 《Wireless Communications, IEEE Transactions on》2008,7(2):495-499
We propose and analyze new finger assignment techniques that are applicable for RAKE receivers in the soft handover (SHO) region. Specifically, extending the results for the case of two-base station (BS), we consider the multi-BS situation, attack the statistics of several correlated generalized selection combining (GSC) stages, and provide closed-form expressions for the statistics of the output signal-to-noise ratio (SNR). By investigating the tradeoff among the error performance, the average number of required path estimations/comparisons, and the SHO overhead, we show through numerical examples that the new schemes offer commensurate performance in comparison with more complicated GSC-based diversity systems while requiring a smaller estimation load and SHO overhead. 相似文献
95.
Calculations and detailed first principle and thermodynamic analyses have been performed to understand the formation mechanism of K2Ti6O13 nanowires (NWs) by a hydrothermal reaction between bulk Na2Ti3O7 crystals and a KOH solution. It is found that direct ion exchange between K+ and Na+ plus H+ interactions with [TiO6] octahedra in Na2Ti3O7 promote the formation of an intermediate H2K2Ti6O14 phase. The large lattice mismatch between this intermediate phase and the bulk Na2Ti3O7 structure, and the large energy reduction associated with the formation of this intermediate phase, drive the splitting of the bulk crystal into H2K2Ti6O14 NWs. However, these NWs are not stable because of large [TiO6] octahedra distortion and are subject to a dehydration process, which results in uniform K2Ti6O13 NWs with narrowly distributed diameters of around 10 nm. 相似文献
96.
如何对接入网络的用户进行身份认证、授予相应权限并进行计费,是卫星移动通信系统网络管理需解决的重要问题。简要介绍认证、授权、计费(AAA)的基本概念,分析Diameter协议框架、协议原理以及协议应用于网络接入的特点。阐述协议中包含的各种应用,给出Diameter NASREQ应用的一种系统模型。重点研究Diameter NASREQ协议在卫星移动通信系统中的应用,详述应用中客户机和服务器中各模块的功能和工作原理。通过分析,说明该应用的可行性及有效性。 相似文献
97.
Tian Xiao Qing Huo Liu 《Antennas and Propagation, IEEE Transactions on》2008,56(3):765-773
In this paper, we present an enlarged cell technique (ECT) to avoid the time step reduction encountered in the conformal finite-difference time-domain (CFDTD) method due to small irregular cells truncated by metallic boundaries. We focus our efforts on the discussion of the accuracy and stability of the ECT and its comparison with other conformal methods, especially the one called the uniformly stable conformal (USC) method. We also provide a simplified ECT, which is much easier to implement. In the ECT, a stability criterion is first constructed to identify instable irregular cells, i.e., those having so small an area to cause instability. Those instable cells are then enlarged into their adjacent cells to obtain a large, stable area. Careful treatment is performed on the communication between the intruding and intruded cells in terms of electromotive force by keeping the total electromotive force conservative. This technique is verified by several 3-D numerical experiments. Results show that the ECT is second-order accurate and numerically stable at the regular Courant time step limit. 相似文献
98.
对在五坐标数控加工中心上铣制三元流叶轮时出现的叶轮附面尺寸误差问题,进行了详细分析,并提出了问题的解决方法,有效地避免了加工中产生的超差。 相似文献
99.
Yawei Li Shaobai Sang Shengli Jin Chunyan Yang Nan Li 《Journal of Materials Science》2006,41(18):5815-5819
Synthesis of Mg-α-Sialon has been investigated by the mixture of silicon, aluminum and magnesia powders in a flowing nitrogen atmosphere in the range of 1300–1600 °C, when Mg-α-Sialon is designed with a chemical formulation of Mg
x
Si12−3x
Al3x
O
x
N16−x
in present work. The results showed that Mg-α-sialon initially occurred at 1400 °C and basically increased with elevated temperatures. For the samples of x = 0.6, 0.8 and 1.0 the products mainly consisted of Mg-α-Sialon with small amounts of Si, AlN and 21R AlN-polytypoid phases at 1600° C. However, in final products of x = 1.2, 1.4 and 1.6 only a little of Mg-α-Sialon formed and a great amount of Si remained in these samples at all the fired temperatures. Fortunately, the content of Mg-α-Sialon in these samples were obviously increased by adding a small amount of α-Si3N4 as seeds before nitridation. 相似文献
100.