论直流电动机换向火花的检测与调整

本文着重探讨直流电动机换向火花的形成、征状以及使用的一些对其进行判别、调整的简单方法，并阐述其原理及效果。     

试述小城镇建设中的生态旅游规划——以江苏省宝应县生态旅游规划为例

生态旅游是以生态环境、生态类型和生态资源为主要旅游对象,以欣赏大自然风光、接受生态知识的科普教育或探索、研究生态科学为主要内容及目的的综合性旅游类型。一、生态旅游规划的原则(一)保护优先原则保护有价值的自然与文化景观资源以及生态环     

In Google We Trust: Users' Decisions on Rank, Position, and Relevance

An eye tracking experiment revealed that college student users have substantial trust in Google's ability to rank results by their true relevance to the query. When the participants selected a link to follow from Google's result pages, their decisions were strongly biased towards links higher in position even if the abstracts themselves were less relevant. While the participants reacted to artificially reduced retrieval quality by greater scrutiny, they failed to achieve the same success rate. This demonstrated trust in Google has implications for the search engine's tremendous potential influence on culture, society, and user traffic on the Web.     

New Solution Approaches to the General Single- Machine Earliness-Tardiness Problem

This paper addresses the general single-machine earliness-tardiness problem with distinct release dates, due dates, and unit costs. The aim of this research is to obtain an exact nonpreemptive solution in which machine idle time is allowed. In a hybrid approach, we formulate and then solve the problem using dynamic programming (DP), while incorporating techniques from branch-and-bound (BB). This approach (DP-BB) has been proven to be effective in solving certain types of scheduling problems. We further propose a new adaptation of the approach to a general problem with a nonregular objective function. To address some shortcomings of DP-BB, we also apply a BB approach in which partial dynamic programming dominance (BB-PDP) is exploited. Computational experiments were conducted with randomly generated test instances in order to evaluate the effectiveness of the two approaches. The results clearly showed that our new approaches can solve all the instances with up to 40 jobs and most of the instances with 50 jobs, which outperforms those frequently used approaches in scheduling research.     

Non-contact measurement of the mechanical properties of materials using an all-optical technique

Describes an optically-based measurement mechanism which realizes a totally noncontact assessment of the most important mechanical properties of structural materials - namely effective stiffness and Poisson ratio. These parameters are sensitive indicators of material integrity. The technique uses laser generated broadband ultrasound as a probe and interferometric optical detection as the detector again exploiting the broadband capability of optics in both space and time. Both detection and excitation systems are most conveniently realized in practical systems through optical fiber linkages. Observing the coupled waveforms between source and detector as a function of source: detector separation after a space : time Fourier transform yields a set of dispersion curves for the ultrasonic (typically Lamb wave) transfer function of the sample. This, in turn, can be inverted using curve fitting routines to obtain effective values of modulus and stiffness. An initial assessment of this inversion process is presented and demonstrates that the effective modulus can be extracted with a confidence level of better than a few percent with slightly larger errors in the Poisson ratio.     

Kinetics and mechanism of carbothermic reduction of magnesia

The reaction between MgO and graphite powders under flowing argon atmosphere was studied using a dynamic thermogravimetric method. In the temperature range 293 to 1973 K, the effects of compacting pressure, magnesia/carbon ratio, heating rate, Ar carrier-gas flow rate, and CO-partial pressure were investigated. An experimentally determined reaction mechanism was proposed and discussed. The reduction process could be divided into two stages. The first stage includes the direct reaction between MgO and graphite particles and partial gas-solid reaction at relatively low temperature (below 1750 K). The overall reaction rate depends on the solid phase-boundary reaction between magnesia and carbon particles. The second stage is the gas-solid reaction between CO and MgO, which determines the overall reaction rate. The apparent activation energies of the two stages were estimated to be 208.29 and 374.13 kJ/mol, respectively.     

柳钢混铁炉炉衬结构及运行管理的技改实践

针对混铁炉使用过程中出现的各种侵蚀状况，设计采用砖砌十浇注复合炉衬结构，特别对前墙拐角和后墙中段等侵蚀快的关键部位作了有针对性的技术改进；在运行管理上，制定推行全新的工艺操作规程，取得了显著的使用效果。     

Red Wine Polyphenols for Cancer Prevention

Conventional cancer therapies, the second leading cause of death worldwide, result in serious side effects and, at best, merely extend the patient''s lifespan by a few years. Searching for effective prevention is of high priority in both basic and clinical sciences. In recent decades natural products have been considered to be an important source of cancer chemopreventive agents. Red wine polyphenols, which consisted of various powerful antioxidants such as flavonoids and stilbenes, have been implicated in cancer prevention and that promote human health without recognizable side effects. Since resveratrol, a major component of red wine polyphenols, has been studied and reviewed extensively for its chemopreventive activity to interfere with the multi-stage carcinogenesis, this review focuses on recent progress in studies on cancer chemopreventive activities of red wine polyphenol extracts and fractions as well as other red wine polyphenols, like procyanidin B5 analogues and myricetin.     

短脉冲激光与岩石相互作用机理初探

石油开采过程中，为增大原始岩体的渗流速度，一般采用水压致裂或射孔弹的方法来加以实现，但两种方法都存在一定缺陷。为探索一种新概念石油开采技术，即采用激光技术增大原始岩体的渗透率，对短脉冲激光辐照自然、饱水和饱油状态的花岗岩、大理岩和红砂岩的响应作了初步研究。得到了激光辐照下，岩石试样内烧蚀坑的三维形态以及烧蚀状态与脉冲数的初步关系。结果表明：脉冲激光可以在试样局部产生一定的裂纹；饱油试样的烧蚀情况较饱水和自然状态更严重。但对于产生的裂纹数量，尺寸以及方向等方面的控制尚需进一步的工作。     

杀菌剂异螺环-4-烯-2,3-5''''-氯-吲哚的合成

研究了以薯蓣皂素(diosgenin)为原料,根据活性叠加原理,在分子中引入一个新的活性基团吲哚环,合成了全新化合物异螺环-4-烯-2,3-5'-氯-吲哚.杀菌药效试验结果表明:所设计的全新目标化合物具有原料所没有的杀菌活性.