建筑隔震技术及其应用

介绍了结构隔震原理,并对隔震技术的优点、隔震系统及其设计注意要点进行了阐述,最后对隔震结构的设计要求、测试及隔震技术的发展因素进行了分析论述,以提高结构的稳定和安全性能。     

Growth and characterization of well-aligned densely-packed rutile TiO(2) nanocrystals on sapphire substrates via metal-organic chemical vapor deposition

Well-aligned densely-packed rutile TiO(2) nanocrystals (NCs) have been grown on sapphire (SA) (100) and (012) substrates via metal-organic chemical vapor deposition (MOCVD), using titanium-tetraisopropoxide (TTIP, Ti(OC(3)H(7))(4)) as a source reagent. The surface morphology as well as structural and spectroscopic properties of the as-deposited NCs were characterized using field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), selected-area electron diffractometry (SAED), x-ray diffraction (XRD) and micro-Raman spectroscopy. FESEM micrographs reveal that vertically aligned NCs were grown on SA(100), whereas the NCs on the SA(012) were grown with a tilt angle of ～33° from the normal to substrates. TEM and SAED measurements showed that the TiO(2) NCs on SA(100) with square cross section have their long axis directed along the [001] direction. The XRD results reveal TiO(2) NCs with either (002) orientation on SA(100) substrate or (101) orientation on SA(012) substrate. A strong substrate effect on the alignment of the growth of TiO(2) NCs has been demonstrated and the probable mechanism for the formation of these NCs has been discussed.     

Political Risks: Analysis of Key Contract Clauses in China's BOT Project

The reforms introduced by the International Monetary Fund in Asia will bring about greater transparency in the economies and innovative approaches in procurement of contracts. China has taken new initiatives in build, operate, and transfer (BOT) infrastructure projects. It is, however, important to analyze and manage the unique or critical risks associated with China's BOT projects. This is especially so after new policies were introduced in late 1996 when the first state-approved BOT project, the U.S. $650,000,000 2 × 350 MW coal-fired Laibin B Power Plant (Laibin B), was awarded. These include the competitive tendering process and 100% foreign ownership of the operating company. An international survey on risk management of BOT projects in China was conducted to seek the views of practitioners. The overall objectives of the survey are (1) to identify the unique or critical risks associated with China's BOT projects; (2) to evaluate the effectiveness of measures for mitigating these risks; (3) to examine the key contract clauses used in Laibin B's concession agreement; and (4) to provide a risk management framework for investing in future BOT projects in China. This paper discusses the adequacy of key contract clauses in Laibin B's concession agreement related to the political and force majeure risks in China, from the perspective of foreign developers, lawyers, and lenders. The contract clauses discussed include changes in law, corruption, delay in approval, expropriation, and force majeure. Areas for further improvement in the clauses are suggested.     

Sampling plans for vehicle component reliability verification

Today's vehicle customers' demand for better quality and reliability is increasing. A typical reliability requirement is that of a lower bound on product reliability at a pre‐specified design life target (called the ‘bogey’) with specified confidence. For the purpose of reliability verification, one way to verify conformance to the requirements is to perform a test and terminate it after running for a certain period of time, cycles or mileage and to make a decision according to the test criterion. The approach presented in this paper specifically addresses the means to design tests that satisfy these important requirements and objectives. All the mathematical derivations are primarily based on a component life distribution that is assumed to follow a Weibull distribution with an assumed value of the shape parameter. By the proposed approach, only the GEM table (derived from the exponential case) is required. The test engineer has the option of trading off between the quantity of samples and the test bogey ratio (the test length relative to the bogey) so as to meet the specific objectives under the constraints. Copyright © 1999 John Wiley & Sons, Ltd.     

The Effect of Temperature on the Tribological Behavior of RBD Palm Stearin

The wide use of petroleum-based oils raises concerns with regard to pollution, and the rising of awareness of greenhouse gases has created a demand for the use of environmentally friendly and biodegradable lubricants for industrial applications. Vegetable oils are one of the bio-oils that have been promoted as a replacement for petroleum products, in part due to their environmentally friendly characteristics; they are nontoxic, biodegradable, and easy to dispose of. Many researchers have performed studies on sunflower oil, corn oil, and soy oil, but few have studied palm oil as a lubricant. Palm oil produced in a high-throughput manner could fulfill the demand for bio-based lubricants. In this study, the influence of temperature on friction and wear performance for refined, bleached, and deodorized (RBD) palm stearin and additive-free paraffinic mineral oil is presented. The experiments were conducted using a four-ball tribotester. Test temperatures of 55, 65, 75, and 85°C were used. The sliding speeds were set to 1,200 rpm. Experiments were run for 1 h under a 392.4 N load. The results of RBD palm stearin were compared with those of paraffinic mineral oil. The experimental results showed that the RBD palm stearin had better performance compared to paraffinic mineral oil in terms of reducing frictional constraints.     

Heat transfer enhancement by recirculating flow within liquid plugs in microchannels

Plug flow can significantly enhance heat transfer in microchannels as compared to single phase flow. Using an analytical model of flow field, heat transfer in plug flow is investigated. The constant-surface-temperature boundary condition is considered. Three stages of the heat transfer in plugs are identified: (i) development of thermal boundary layer; (ii) advection of heated/fresh fluid in the plug; and (iii) thermally fully developed flow. Due to the transport of heated fluid and fresh fluid within the plug by the recirculating flow, oscillations of the Nusselt number at high Peclet numbers are observed and explained. The effects of the Peclet number and the plug length on the heat transfer process are evaluated. The results show that short plugs are preferable to long plugs since short plugs result in high Nusselt numbers and high heat transfer indices.     

First Public-Private-Partnership Application in Taiwan’s Wastewater Treatment Sector: Case Study of the Nanzih BOT Wastewater Treatment Project

Taiwan has been promoting public-private-partnership (PPP) projects in the wastewater treatment sector with the aim of improving its sustainable environment and increasing its wastewater treatment rate. The Nanzih Wastewater Treatment Project is the first PPP application in Taiwan’s wastewater treatment sector. It provides important experiences and lessons for both the public and private sectors. This paper presents a detailed study of its tender process, concession agreement, financial structure, payment mechanism, and risk management. It explains the key features of the project and provides conclusive findings on the lessons learned. These observations should be useful for practitioners and academia who are interested in the development of future PPP wastewater treatment projects in Taiwan.     

Coping strategies of households affected by flooding: A case study of Sekondi-Takoradi Metropolis in Ghana

Annually, rivers close to communities within Sekondi-Takoradi Metropolis overflow their banks, especially during the rainy seasons; displacing thousands of residents. Despite this, little is known about the coping strategies used by the residents when flooding occurs. Using mixed method, this article examines the coping strategies employed by households within three communities at risk. Two hundred and seven heads of households residing in Eshiem, Kansawurodo and Whindo were systematically selected to fill in questionnaires, while six key informants comprising chiefs and representatives of flood management institutions were chosen for in-depth interviews. The findings suggest that the commonest coping strategies adopted by residents in all the communities were: temporary vacation of homes, transfer of relevant properties to neighbors and building of flood steps. However, the coping strategies employed by the residents varied by communities, although the majority of them resorted to self-sustaining mechanisms in restoring their losses.     

Optical response characteristics arising from delocalized electrons in phase change materials

Phase change materials have great potential for data storage applications owing to the large optical and electrical contrasts during rapid switching between their amorphous and crystalline phases. Hence, significant efforts have been made to identify and understand their unique characteristics. Here, we report a distinct optical characteristic of phase change materials and explain its presence via electronic structure considerations. The optical response of phase change materials and non-phase change materials are investigated via experiments. Annealing them from room temperature to 400 °C, we observed that Sb₂Te₃ exhibits phase change properties but not Bi₂Te₃, despite their similar crystal structures. A red shift in the absorption spectra is observed for crystalline Sb₂Te₃ with respect to its amorphous phase. From first-principles calculations, we explain that the delocalized electrons in crystalline Sb₂Te₃ films are responsible for this red shift. In contrast, the electrons in Bi₂Te₃ films are localized and no absorption red shift is observed. The absorption red shift is also observed in other phase change materials from the GeTe–Sb₂Te₃ pseudo-binary system; hence the detection of such a red shift may be used for identifying potential phase change materials.