Calculation of the Average Coefficient of Thermal Expansion in Oriented Cordierite Polycrystals

In this work, the calculation of the average value of a physical quantity in a textured polycrystal is presented. The method is applied to the coefficient of thermal expansion in cordierite samples, presenting domain and crystal preferred orientation, and compared with experimental data. The knowledge of the experimental or simulated texture intensity function is required to calculate the orientation distribution function. Then, a sum over all oriented crystals, weighted by their population, is carried out. It is shown that this sum must be carried out differently, if different components of the physical quantity (usually a tensor) must be calculated. Results show a very good agreement between the model and the experimental data obtained (a) by neutron diffraction as a polycrystalline average and (b) by dilatometry on real cordierite materials used as diesel particulate filters. Although the method is resting on the possibility of having a simple analytical form of the texture intensity, its numerical implementation does not present any problem.     

Planning order releases for an assembly system with random operation times

A multi-stage assembly network is considered. A number of end items should be delivered at a certain time. Otherwise a delay cost is incurred. End items and components that are delivered before they are needed will cause holding costs. All operation times are independent stochastic variables. The objective is to choose starting times for different operations in order to minimize the total expected costs. We suggest an approximate decomposition technique that is based on repeated application of the solution of a simpler single-stage problem. The performance of our approximate technique is compared to exact results in a numerical study.     

Le Havre电厂4号和Cordemais电厂4号及5号600 MW燃煤机组脱NOX技术

介绍了法国电力公司在Le Havre电厂4号和Cordemais电厂4、5号600 MW燃煤机组进行NOX减排的工程实施情况,针对所遇到的困难采取的技术措施,分析了可供借鉴的经验和可吸取的教训.     

Dissociation of Temporal Dynamics of Heart Rate and Blood Pressure Responses Elicited by Conditioned Fear but Not Acoustic Startle.

Fear-inducing stimuli were hypothesized to elicit fast heart rate (HR) responses but slow mean arterial blood pressure (MAP) responses and thus were studied in auditory fear conditioning and acoustic startle at high temporal resolution in freely moving mice and rats. Fear-induced instantaneous acceleration of HR reaching maximum physiological values and subsequent recovery to baseline were observed. The MAP response consisted of an immediate, mild, and transient increase followed by a sluggish, profound elevation and slow recovery. HR and MAP responses served as reliable indicators of conditioned fear in mice with dissociated temporal dynamics. Unconditioned auditory stimuli, including acoustic startle stimuli, elicited only fast, mild, and transient MAP and HR elevations in mice and rats, reflecting arousal and attention under these experimental conditions. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Observation and characterization of defects in HfO2 high-K gate dielectric layers

A deeper understanding of Hf-based high-K materials in terms of their structural and electrical defects is important for device implementation. We have studied the occurrence of such defects using wet-etch defect delineation, electron microscopy, depth-profiling and conventional electrical measurements. It is evident that defects are present in HfO₂ films that are related to the microstructure and stoichiometry of the film, which in turn depend on the deposition temperature, starting surface and post-deposition treatments. These results appear to be independent of the deposition technique. Two types of defects were observed, those that are physically visible and cause immediate failures especially on large-area structures, and those that cause high leakage but not immediate failures. The existence of defects affects not only leakage or performance but will also affect the reliability through trapping of charge at the defect sites. As films continue to be scaled thinner, the requirements on defect reduction to minimize electrical impact may become more stringent.     

Cardiovascular effects of mibefradil in hypertensive patients with obstructive sleep apnea

OBJECTIVE: Hypertension is often seen in obstructive sleep apnea (OSA) and is characterized by increased sympathetic activity, depressed baroreflex and accentuated vascular responsiveness. The objective of this study was to investigate the effects of the new T-selective calcium channel blocker mibefradil on invasively measured blood pressure (BP) and heart rate in hypertensive patients with OSA. METHODS: The present study was a double-blind, randomized and placebo-controlled before and after trial in two parallel groups. Fifty-three men aged 23 69 years with systemic hypertension and OSA were recruited from the Outpatient Department of the Marburg University Sleep Laboratory and hospitalized for 10 days. Mibefradil (50 mg) or placebo were given orally in the morning for 8 days. The main outcome measure was the mean arterial (radial) BP monitored continuously during nocturnal sleep and during standardized daytime physical and psychological performance testing. RESULTS: Mibefradil lowered mean arterial BP and heart rate with (SD) during the entire measurement period compared with placebo: -7.25 (9.59) vs -2.11 (8.43) mmHg (P=0.039) and -4.83 (5.94) vs -1.34 (4.13) bpm (P=0.022), respectively. Both effects were observed during nocturnal sleep and performance testing, including graded exercise. Adverse events did not differ compared with placebo. CONCLUSION: Mibefradil is an effective but well-tolerated antihypertensive that also lowers heart rate over 24 h in OSA, in conditions known to increase BP.     

Mercury emission control in coal-fired plants: The role of wet scrubbers

When coal is combusted, the combination of the elevated temperature and the volatility of mercury and its compounds results in the presence of gaseous elemental mercury and mercury compounds in the combustion flue gas. In January 2005, the European Commission adopted a mercury strategy that envisages a number of measures to reduce mercury levels in the environment and human exposure. A number of options for mercury removal from coal-fired power plants have been investigated. However, more effort is needed to achieve an efficient and cost-effective technology. The main objective of this work is to investigate the influence of scrubber parameters on mercury removal efficiency to establish effective measures for mercury control. In order to attain these objectives, theoretical predictions based on thermodynamical equilibrium data and lab-scale experimental tests were carried out. The results obtained point to pH and slurry concentration as the most critical parameters for converting FGD (Flue Gas Desulphurization unit) into a multipollutant control technology.     

Formal models and algorithms for decentralized decision making under uncertainty

Over the last 5 years, the AI community has shown considerable interest in decentralized control of multiple decision makers or “agents” under uncertainty. This problem arises in many application domains, such as multi-robot coordination, manufacturing, information gathering, and load balancing. Such problems must be treated as decentralized decision problems because each agent may have different partial information about the other agents and about the state of the world. It has been shown that these problems are significantly harder than their centralized counterparts, requiring new formal models and algorithms to be developed. Rapid progress in recent years has produced a number of different frameworks, complexity results, and planning algorithms. The objectives of this paper are to provide a comprehensive overview of these results, to compare and contrast the existing frameworks, and to provide a deeper understanding of their relationships with one another, their strengths, and their weaknesses. While we focus on cooperative systems, we do point out important connections with game-theoretic approaches. We analyze five different formal frameworks, three different optimal algorithms, as well as a series of approximation techniques. The paper provides interesting insights into the structure of decentralized problems, the expressiveness of the various models, and the relative advantages and limitations of the different solution techniques. A better understanding of these issues will facilitate further progress in the field and help resolve several open problems that we identify. This work was done while S. Seuken was a graduate student in the Computer Science Department of the University of Massachusetts, Amherst.     

An inductive theory of regional development

Regional development tendencies in Western Europe in recent decades are analyzed. They show a mosaic-like pattern of dynamic and declining regions in all parts of Europe, while there is no uniform core/periphery polarization. On this basis, an inductive theory of regional development in economically advanced societies is constructed. It states that the structural composition of the economy of each region plays a role in its development. However, locational shifts occur within all sectors. Whether a region gains or loses depends largely on the local conditions, such as political institutions, regional policy assistance, infrastructure, supply of skilled people, social qualifications, factor prices and population density. This theory fits well into the picture of the emerging service society.