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运用扫描电镜图像、红外光谱分析及吸附量测定等手段。系统地研究选择性絮凝剂FD在微细粒黑钨矿颗粒表面的吸附作用。在黑钨矿颗粒表面,Fe2 的晶体场稳定能大于Mn2 ,是较迟钝的离子,Mn2 活性较强。FD在徽细粒黑钨矿颗粒表面形成特性吸附,FD可使徽细粒黑钨矿和磁铁矿形成致密而稳定的复合聚团。分散剂(NaPO3)6不影响FD在黑钨矿表面的吸附,磁铁矿对FD的吸附量则随(NaPO3)6用量的增加而减小。 相似文献
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Kensuke Konishi Jun-Ichi Toyooka Kenji Kamiyama Ikken Sato Shigenobu Kubo Shoji Kotake Kazuya Koyama Alexander D. Vurim Valery A. Gaidaichuk Alexander V. Pakhnits Yuri S. Vassiliev 《Nuclear Engineering and Design》2007,237(22):2165-2174
The WF (wall failure) test of the EAGLE program, in which 2 kg of uranium dioxide fuel-pins were melted by nuclear heating, was successfully conducted in the IGR (Impulse Graphite Reactor) of NNC/Kazakhstan. In this test, a 3 mm-thick stainless steel (SS) wall structure was placed between fuel pins and a 10 mm-thick sodium-filled channel (sodium gap). During the transient, fuel pins were heated, which led to the formation of a fuel-steel mixture pool. Under the transient nuclear heating condition, the SS wall was strongly heated by the molten pool, leading to wall failure. The time needed for fuel penetration into the sodium-filled gap was very short (less than 1 s after the pool formation). The result suggests that molten core materials formed in hypothetical LMFBR core disruptive accidents have a certain potential to destroy SS-wall boundaries early in the accident phase, thereby providing fuel escape paths from the core region. The early establishment of such fuel escape paths is regarded as a favorable characteristic in eliminating the possibility of severe re-criticality events. A preliminary interpretation on the WF test results is presented in this paper. 相似文献
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对于函数依赖、多值依赖都建立了正确(sound)、完备的(complete)公理系统.对于嵌入型多值依赖的正确、完备的公理系统问题,Sagir、Walacka 已证明它没有有限公理系.但嵌入型多值依赖作为特殊情况包含的型板依赖被定义之后,它的成员问题已有半判定方法.特别是对嵌入型多值依赖集合作一些限制后,它的成员问题可解性已被提出.本文对 Chase过程作了更改后,形成 N-Chase 过程,并利用它对一种嵌入型多值依赖集证明了其成员问题的可解性. 相似文献
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Explicit solution techniques have been widely used in geotechnical engineering for simulating the coupled hydro-mechanical (H-M) interaction of fluid flow and deformation induced by structures built above and under saturated ground, i.e. circular footing and deep tunnel. However, the technique is only conditionally stable and requires small time steps, portending its inefficiency for simulating large-scale H-M problems. To improve its efficiency, the unconditionally stable alternating direction explicit (ADE) scheme could be used to solve the flow problem. The standard ADE scheme, however, is only moderately accurate and is restricted to uniform grids and plane strain flow conditions. This paper aims to remove these drawbacks by developing a novel high-order ADE scheme capable of solving flow problems in non-uniform grids and under axisymmetric conditions. The new scheme is derived by performing a fourth-order finite difference (FD) approximation to the spatial derivatives of the axisymmetric fluid–diffusion equation in a non-uniform grid configuration. The implicit Crank-Nicolson technique is then applied to the resulting approximation, and the subsequent equation is split into two alternating direction sweeps, giving rise to a new axisymmetric ADE scheme. The pore pressure solutions from the new scheme are then sequentially coupled with an existing geomechanical simulator in the computer code fast Lagrangian analysis of continua (FLAC). This coupling procedure is called the sequentially-explicit coupling technique based on the fourth-order axisymmetric ADE scheme or SEA-4-AXI. Application of SEA-4-AXI for solving axisymmetric consolidation of a circular footing and of advancing tunnel in deep saturated ground shows that SEA-4-AXI reduces computer runtime up to 42%–50% that of FLAC's basic scheme without numerical instability. In addition, it produces high numerical accuracy of the H-M solutions with average percentage difference of only 0.5%–1.8%. 相似文献
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分形维数计算具有计算复杂度高、计算时间长等特点,严重影响计算的实时性。针对此问题,在充分分析分形维数计算内在特性的基础上,利用分形维数具有流水线计算的特点,提出了一种计算分形维数的流水线体系结构,可有效提高分形维数计算的实时性。由于嵌入式并行处理硬件平台资源有限,对分形维数计算实时性进行优化的同时还需要考虑资源消耗的优化。通过对不同级数流水线运行时间和资源消耗的分析,建立基于运行时间与资源消耗的优化目标函数,从而得到运行时间与资源消耗最优的流水线结构。并与已有的计算分形维数的并行算法进行对比分析,实验结果表明,本文提出的优化方法在提高计算实时性的同时有效降低了资源消耗,实现了运行时间与资源消耗的优化。 相似文献
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Erik Abenius Ulf Andersson Fredrik Edelvik Lasse Eriksson Gunnar Ledfelt 《International journal for numerical methods in engineering》2002,53(9):2185-2199
We present a new approach to time domain hybrid schemes for the Maxwell equations. By combining the classical FD‐TD scheme with two unstructured solvers, one explicit finite volume solver and one implicit finite element solver, we achieve a very efficient and flexible second‐order scheme. The second‐order accuracy of the hybrid scheme is verified through convergence studies on perfectly conducting as well as dielectric and diamagnetic circular cylinders. The numerical results also show its superiority to the FD‐TD scheme. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
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EI源出现M 2H峰是很罕见的现象。在研究五种醌亚胺染料时,发现它们的M 2H峰显著大于M峰,其强度比值(M 2H/M)随蒸发温度升高而增加。接照FD的数据和D_2O、D_2的实验结果,认为上述现象是属于热氢转移,它与能承受大热应力的醌亚胺染料分子有关,而与周围的条件无关。 相似文献