Searching Databases with Keywords

Traditionally, SQL query language is used to search the data in databases. However, it is inappropriate for end-users, since it is complex and hard to learn. It is the need of end-user, searching in databases with keywords, like in web search engines. This paper presents a survey of work on keyword search in databases. It also includes a brief introduction to the SEEKER system which has been developed.     

科技无极限之CPU篇

从本期开始,我们将针对目前PC中的配件为大家分析其诞生、发展的历程和未来走向预测,希望大家喜欢!有任何意见、建议可发送电子邮件至azuryice@pophardcom.cn     

A Broadcast Mechanism Supporting Power-Conserving Mobile Stations<Superscript>*</Superscript>

Power saving is an important issue in the mobile computing environment. In this paper, we propose a broadcast mechanism which constructs the broadcast channels according to the access frequency of each disseminated kind of message in order to save power in mobile stations. The pinwheel scheduling algorithm presented in this paper is used to organize all kinds of messages in the broadcast channels in a most symmetrical distribution for reducing both tuning time and access time. Performance of the proposed mechanism is analyzed and the improvement is demonstrated with numerical results. The results show that the proposed mechanism is capable improving both tuning time and access time as the skew access characteristic exists among the disseminated messages. ^*This work was supported in part by the National Science of Council, R.O.C., under Contract NSC94-2213-E-130-003.     

Human response to blast-induced vibration and air-overpressure: an Indian scenario

Ground vibration (V_max) and air-overpressure/noise (p) are some of the negative effects of blasting. The associated human annoyance and complaints are expected to show an increasing trend in the future as there is no economically viable alternative to blasting in mines in India.A study of the human response to blasting in four mining localities across India has shown that the response is not simply political, as frequently assumed. It has been found that irrespective of those questioned, a basic concern for the safety of property was the main response. There was a greater response from the middle-aged and middle-educated while fewer women than men responded. Assuming that a 100% negative response from the inhabitants will translate into complaints, a methodology is suggested to take account of the human response criteria when considering blasting within 400 m of habitations.     

Wear resistance of amorphous-crystalline detonation coatings with solid lubricant additive in vacuum

Detonation amorphous-crystalline coatings Zr–Si–B that additionally contain solid lubricant additive as an anti-friction component in the form of the dispersed molybdenum disulfide have been developed. The high wear resistance of coatings that contain molybdenum disulfide has been noted. In a study of the surface layer, photomicrographs of friction surfaces on which activation processes take place have been used in electron diffraction analysis. The wear resistance of the coatings has been established, which enabled the creation of separating juvenile thin film surface of an object that represented the product of oxygen-free structures based on chemical elements of intermetallic phases included in the coating composition.     

Biocompatibility of surface treated pure titanium and titanium alloy by<Emphasis Type="Italic">in vivo</Emphasis> and<Emphasis Type="Italic">in vitro</Emphasis> test

In the present study, commercial pure Ti and Ti-6Al-4V alloy specimens with and without alkali and heat treatments were implanted in the abdominal connective tissue of mice. Conventional stainless steel 316L was also implanted for comparison. After three months, their biocompatibility was evaluated byin vitro andin vivo experiments. Surface structural changes of specimens due to the alkali treatment and soaking in Hank’s solution were analyzed by XRD, SEM, XPS and AES. An apatite layer, which accelerates the connection with bone, was formed more easily on the alkali treated specimens than the non-treated specimens. The number of macrophages, which is known to increase as the inflammatory reaction proceeds, was much lower for the alkali and heat treated specimens than for the others. The average thickness of the fibrous capsule formed around the implant was much thinner for the alkali and heat treated specimens than for the others.