Tank模型及其在边坡水位预测中的应用

 Tank模型可以模拟非线性的降雨–地下水运移过程,并且能迅速得到解答。基于现有的单列tank模型,提出新的复合水箱模型。由于新模型参数超过20个,应用传统优化算法难以快速找到最优解,一种新的启发式自搜索算法(变维数搜索算法)被引入并改进后用于模型最优解的寻找。变维数搜索算法能够根据搜索进程的变化自动改变搜索维数并且快速找到最优解。27个参数的复合tank模型被应用于日本国道九号线的一个边坡,计算结果表明：变维数搜索算法能够在10 min左右找到合适的最优解;降雨过程复合tank模型计算的地下水位变化和观测值非常接近。最后通过和有限单元法计算结果的比较表明,有限单元法的计算结果受地质渗透特性的影响很大,而复合tank模型不存在这种问题。工程实例计算表明,该方法和监测结果比较一致,但其适应性更强,特别适用于没有进行足够地质结构探查的边坡。它能够快速反映降雨过程中地下水位的运移过程,可以推广使用。     

EFFECTS OF DIETARY PLANT CEREBROSIDE ON GENE EXPRESSION IN THE LARGE INTESTINE OF 1,2-DIMETHYLHYDRAZINE (DMH)-TREATED MICE DETERMINED BY DNA MICROARRAY ANALYSIS

The effects of dietary plant cerebroside on colon gene expression by DNA microarray analysis in 1,2-dimethylhydrazine (DMH)-treated mice were investigated. After 9 weeks of feeding with DMH, decreases and increases in the levels of expression of 110 and 145 genes were detected, respectively. Especially, the expression of Soggy-1, which suppresses the Wnt signaling pathway, was increased, while that of Ras-associated protein, which induces the mitogen-activated protein (MAP)-kinase pathway and is responsible for the development of aberrant crypt foci (ACF), was decreased. The results of the present study indicated that dietary cerebroside in DMH-treated mice regulates the Wnt signaling and MAP-kinase pathways, and prevents the development of ACF in the large intestine.

PRACTICAL APPLICATIONS

Dietary plant cerebroside increased expression of Soggy-1 mRNA, which suppresses the Wnt signaling pathway, and decreased expression ofRas-associated protein, which induces the MAP-kinase pathway in 1,2-dimethylhydrazine (DMH)-treated mice. The results of the present study indicated that dietary cerebroside in DMH-treated mice regulates the Wnt signaling and MAP-kinase pathways, and prevents the development of aberrant crypt foci in the large intestine, thus being of potential use for nutraceutical applications.     

Soft‐Switching Interleaved PFC Converter with Lossless Snubber

This paper describes a soft‐switching interleaved power factor correction (PFC) converter with a lossless snubber. AC–DC converters require a unity input power factor characteristic with highly efficient operation to prevent the inflow of harmonic current to the power source. The proposed PFC converter improves the input current ripple with interleave control. The converter realizes a high efficiency by the soft‐switching operation of all switching devices without a large auxiliary resonant circuit. This paper introduces the soft‐switching operation of the converter. In order to confirm the validity of the proposed converter, experiments with a prototype of the PFC converter have been performed. The experimental results indicate that the proposed converter can realize the soft‐switching operation of all switching devices, a reduction in the input current ripple, a unity power factor of 98% or more, a sinusoidal input current, and constant output voltage control. The efficiency of the proposed PFC converter with a lossless snubber is higher than that without the lossless snubber. The results presented in this paper confirm the validity of the proposed converter.     

环境控制与等离子体技术融合对未来高精密抛光难加工材料所构成的挑战

以碳化硅、氮化镓和金刚石为代表的宽禁带半导体材料是典型的难加工材料。本研究中，设计2种基于化学机械抛光（CMP）的加工设备，以开发高效高质量加工此类晶体衬底的新技术，并研究讨论使用新设备时的加工机理和难加工衬底的加工特征。加工设备的原型机分别为封闭箱式（closed chamber-type）环境控制CMP设备和等离子体熔融（plasma fusion）CMP设备。在前者中引入光催化反应，并在高压氧气环境下增加紫外辐射，试图提高加工效率。在后者中预期实现常压等离子体化学蒸发加工（P-CVM）和CMP各自优势的协同效应，尤其适合高硬度、极稳定的金刚石衬底。在验证设备加工机理的过程中，随加工过程进行，在极限表面（extreme surface）上形成了如水合物膜或氧化物膜的反应产物。因此，引入紫外辐射的箱式CMP设备在高压氧气环境下效率极高；而对等离子熔融CMP设备，在氧气氛围下，同时开展P-CVM和CMP时可实现对金刚石晶片的高效加工。通过对加工机理进行研究，提出由伪自由基场（pseudo radical filed）/反应产物形成和新表面接触磁流变抛光这两步构成的“循环处理方法”，可实现对难加工材料的高效率加工。      

SIMPLE STRUCTURE MULTILEVEL INVERTER USEFUL FOR AC MOTOR DRIVES

ABSTRACT

In this paper, a new simplified configuration for a multilevel PWM inverter and its control strategy is proposed. The proposed configuration consists of an auxiliary circuit with four switching devices, and a single full-bridge inverter. For medium power applications, the new circuit design, in which the number of switching devices is reduced, offers characteristics similar to conventional NPC inverters. The control method is based on closed loop regulation of the instantaneous line-to-line output voltages. The proposed scheme is simple, has fast response, and is effective for reducing the size of the DC-link capacitors. The performance of the system is verified by computer simulation and by practical experience