Infrared Study of Adsorbed Trans-Stilbene and Azobenzene

Previous reflectance study in our laboratory has shown that stilbenes and azobenzenes adsorbed on alumina or silica undergo a more-or-less reversible loss of olefinic double bond character up on irradiation at appropriate wavelengths, and an intermediate was proposed. The purpose of this work was trying to characterize the intermediate using infrared technique. Stilbene exists in two isomeric forms. The molecular structure of trans-stilbene was found to be almost planar in the solid state with the phenyl rings only slightly twisted from the general plane of the molecule, 1 and a careful study by Suzuki indicates that it is safe to, assume the molecule to be planar in solution as well. The phenyl rings of cis-stilbene are twisted by about 30° to relieve the steric interaction effects in the ortho hydrogens. Both thermal and photoinduced isomerizations are known to occur. Thermal isomerization of cis - stilbene takes place both in solution and in the vapor phase. The energy of activation in solution is 46±2.0 kcal/mole4 and in the vapor phase 42.6±1.0 kcal/mole. The isomerization can occur either through the vibrationally excited ground state or the first excited triplet, where the olefinic bond has less double bond character. Isomerization in solution is catalyzed by radicals such as Br, Lewis acids like A1Cl3 and Broensted acids such as H 2SO4. All have the effect of removing the double bond character from the olefinic bond. In the above-mentioned studies of adsorbed stilbene, the resultant irradiation products were all identified following rapid removal from the surface of the solid matrix. A careful study by Hecht and Jensen13 indicates that trans-stilbene adsorbed on 150°C activated neutral alumina using vacuum line techniques showed a complete loss of the trans peak upon irradiation, followed by a slow return for 22.5 hours at 95°C. The intermediate for irradiated trans-stilbene adsorbed on alumina was also proposed

An Integrated Design Optimization for Monolithic Mechanical Amplifier in PZT Nano-Positioning Stage

[[abstract]]In order to satisfy the accelerating nanotechnology of high-tech precision manufacturing, it is essential to develop the efficient integration of amplifying device producing very fine resolution. This paper proposes such a development using topological optimal synthesis to design a monolithic mechanical amplifying lever actuated by a PZT in single-axis nano-positioning stage. This one-piece compound compliant mechanism consists of an amplifier and nano-motion bed. The resultant amplifier yields to a larger magnification factor than that in original design. The completed design implementation shows that the presenting design optimization is practical to apply. In addition, it provides a creative computational aided design (CAD) environment and integrated design process for mechanical amplifier and nano-positioning stage.[[notice]]補正完畢[[booktype]]紙

Initial Public Offering and Corporate Governance in China's Transitional Economy

This paper empirically investigates the performance of Chinese initial public offerings (IPOs). The data used covers the period from mid-1995 to mid-1999 with the sample including 884 companies (both in the A- and B-share markets). In an examination of growth, profitability and stability of listed companies either individually or as a combination, it can be seen that the only industries in which listed companies in China display strong performance are public utilities, transportation and finance. If one examines the changes in listed companies' financial indicators following the IPO, it becomes apparent that with the exception of earnings related indicators (EPS and ROE) there are no significant changes. What's more, the financial indicators tend to fall rapidly year on year. This means that the IPO is of little obvious help to companies' operational performance, and may actually make things worse. One of the reasons for this is that in order to implement the IPO and secure stock market listing, companies tend to submit inflated figures in the financial statements that they are required to provide. Another possible factor is the poor corporate governance characteristics of Chinese enterprises.

A comparative analysis of the air transport liberalization and global airline alliances on market concentration

As a leading aviation country in the world, the U.S. has open skies agreements with more than 120 countries around the world. In the last twenty years, the three global alliances – Oneworld, Star and Skyteam has grown in parallel with the increased air service liberalization. In 2019, these three global alliances carried about 44% of global passenger traffic, while earning about 66% of global airline revenue. The transatlantic market is highly concentrated among the three global alliances, having 80% of market share on the routes between the U.S. and Europe. Using the three alliances as focal groups, this paper will investigate market concentration on non-stop international routes to and from the U.S. under open-skies and non-open-skies agreements. The key research question addressed will be: whether and to what extent the growth of global alliances may lead open-skies routes to be less competitive as compared to those non-open-skies routes. Policy implications will be drawn and discussed based on the findings of the study

Use of Impaired Waters in Power Plant Cooling Tower System:Review of Regulations and Feasibility Analysis

In 2000, the freshwater withdrawn for industrial use in the U.S., including mining, industrial process usage, power generation, etc., has reached 45% of the total daily freshwater withdrawal of 346 billion gallons. Among these industries, thermoelectric generation is the largest freshwater user with a withdrawal of 136 BGD. Fierce competition for this valuable resource will force difficult decisions to be made about allocation priorities and water availability for electric power production. Studies have shown that impaired waters can be used as alternative water sources for certain applications, including makeup water in electric power plant cooling systems. Among all possible impaired waters that could potentially be used in power production, secondary treated municipal wastewater is the most common and widespread source. Review of regulations that govern water reuse revealed that there are no federal regulations specifically addressing water reuse and that a number of states have implemented their own regulations. Several states were investigated for specific regulations and/or guidelines related to water reuse in power plant cooling water systems.The geospatial analysis performed in this study was designed to evaluate the feasibility of using treated municipal wastewater for cooling in power industry. By utilizing the geoprocessing tools of a geographic information system (GIS), this study evaluated if the water demand of a particular facility can be satisfied by nearby Publicly Owned Treatment Works (POTWs). Datasets of 110 power plants proposed for development and 11785 POTWs were evaluated as part of this feasibility analysis. Estimated cooling water needs for the proposed power plants were compared with the total wastewater flowrates discharged by nearby POTWs. Data analysis revealed that 81% of the proposed power plants would have sufficient cooling water supply from POTWs within a 10 mile radius, while 97% of the proposed power plants would be able to meet their cooling water needs from POTWs located within 25 miles from these plants. On average, 1.15 POTWs were needed to completely satisfy the cooling water demand for each of these power plants. In other words, one fairly large POTW within a reasonable distance from each power plant could meet most of its cooling water needs.Dataset of 407 existing coal fired power plants was also evaluated using the same process. All of the existing power plants were assumed to be renovated to wet recirculating cooling systems regardless of their original design. Results indicate 49.4% of the existing power plants would have sufficient cooling water supply from POTWs within a 10 miles radius; 75.9% of the existing power plants would have sufficient cooling water supply from POTWs within a 25 miles radius. For those power plants which have sufficient water supply, an average number of 1.46 POTWs are required to satisfy the cooling water demand.The tools developed in this study can be used to evaluate a number of scenarios for alternative cooling water supply needed for energy generation in the future. It is clear that the reclaimed municipal wastewater can and will likely play a more prominent role in this critical industrial sector

USE OF CHLORINE, CHLORAMINE, OR CHLORINE DIOXIDE TO CONTROL BIOLOGICAL GROWTH IN POWER PLANT RECIRCULATING COOLING SYSTEMS USING TREATED MUNICIPAL WASTEWATER

Cooling water deficiency due to limited freshwater sources posed an obstacle of expending current thermoelectric power generation in the U.S. and has led the power industry to seek an alternative water resource to meet its cooling water requirement. Of all the potential alternatives, secondary treated municipal wastewater is prominent because of its vast allocation and abundant quantity. However, the impaired water quality and unique environment make the cooling tower management more challenging. Therefore, prudent water quality management with chemicals is required to prevent corrosion, scaling, and biological growth in the cooling systems. This study focused on the understanding of the kinetic, effectiveness, and dosage requirement of chlorine-based biocides (chlorine, chloramine and chlorine dioxide) in the recirculating cooling systems using treated municipal wastewater as makeup. Laboratory-scale studies and pilot-scale cooling systems were used to evaluate the biological growth under realistic conditions associated with full-scale cooling systems. Results of 30-day field tests indicated that the pilot-scale cooling towers developed in this study are reliable for evaluating different chemical regimes by maintaining steady cooling performance under various operating conditions. Direct use of secondary treated effluent for cooling water is a feasible option when using monochloramine as major biocide. The low oxidizing ability of monochloramine resulted in a high residence time and high penetrating ability, and thus provided better biocidal effectiveness against planktonic and sessile heterotrophic bacteria and Legionella in recirculating cooling systems. A minimum monochloramine residual above 3 mg/L in the recirculating cooling water is needed for proper biological growth control with this impaired water. Biological growth potential is comparable in secondary treated effluent subjected to different tertiary treatment (i.e., nitrification, sand filtration, activated carbon adsorption) regardless of total organic carbon concentration in the wastewater. The performance of monochloramine was optimized when the secondary treated effluent was subjected to nitrification and sand filtration. The key findings of this study indicate that biological growth can be controlled in cooling systems using treated municipal effluents as makeup. The biocide regime demonstrated in this study offers a useful guideline to meet biological growth control criteria in recirculating cooling systems