Spectral Analysis of Stochastically Sampled Dynamic Systems

In this paper a spectral analysis methodology is introduced for stochastically sampled linear, dynamic, and stochastic continuous-time systems. This particular problem is considered for the purpose of investigating the spectral analysis issues associated with turbulent velocity measurements. The properties of the equivalent linear discrete-time system allow for the determination of the covariance between observations as a function of the number of in-between measurements. Subsequently, this autocovariance function is analyzed in the frequency domain. Date received: March 31, 1998. Date revised: November 11, 1999.     

Corrosion of high temprature alloys in the primary circuit helium of high temperature gas cooled reactors. – Part I: Theoretical background

The interaction of Ni and Fe-Ni base alloys with the reactive impurities H₂O, CO, H₂ and CH₄ in simulated cooling gas of the primary circuit of the High Temperature Gas Cooled Reactor (HTGR) causes corrosion effects that can significantly influence the mechanical properties. Apart from the formation of surface scales (oxides, carbides or mixed oxides/carbides), structural changes of the alloys are observed; depending on gas composition, gas supply rate and test temperature, carburization or decarburization can occur. In this report it is shown that an interpretation of the basic corrosion effects is possible on the basis of a modified stability diagram for chromium provided that - the kinetics of elementary gas metal reactions are incorporated in the expressions for carbon activity and oxygen partial pressure of the atmosphere and - the gradients of the potentials across the surface scales are taken into account. The interpretation allows the derivation of the corrosion behaviour of NiCr-base alloys in different HTGR helium compositions and enables the limits for the formation of protective chromia surface scales to be given. The influence of alloying elements other than chromium can be explained qualitatively. The results can be transferred to other reactive gas mixtures, which are characterized by an oxygen partial pressure near to the dissociation pressure of the scale forming oxides.     

Improved chitin production by pretreatment of shrimp shells

Pretreatment of shrimp shells was investigated in order to lower the costs and to improve the sustainability of chitin production. Physical pretreatment comprising drying, grinding and sieving is attractive for the recovery of 50% of shrimp protein as a dry powder. Pretreatment of shells by shearing in acidified water results in the removal of up to 60% of the protein and a reduction of their mineral content without a decrease in the chitin yield. Both pretreatment procedures will lead to cleaner technology for chitin production, to a considerably lower need for chemicals, to useful protein by‐products, and to less‐contaminated industrial effluent. Copyright © 2004 Society of Chemical Industry     

Technology, society, and culture: A framework for understanding

The many specific studies of science-technology-society relationships fail to provide a general framework for understanding the fundamental transformation that is taking place in human society. An analysis of the central role of culture in traditional societies—and how technology competes with and partially replaces culture as a mediating factor in human experience—can provide the basis for such a framework by thorough recognition of the phenomenon of Technique. This concept also provides some guidance for practical responses to the diverse problems characteristic of our society.     

The referents of trait inferences: The impact of trait concepts versus actor–trait links on subsequent judgments.

The authors investigated the hypothesis that when trait inferences refer to abstract behavior labels they act as a general interpretation frame and lead to assimilation in subsequent judgments of an ambiguous target, whereas when they refer to a specific actor–trait link they will be used as a scale anchor and lead to contrast. Similar to G. B. Moskowitz and R. J. Roman's (see record 1992-31124-001) study, participants who were instructed to memorize trait-implying sentences showed assimilation, and participants who were instructed to form an impression of the actors in these sentences showed contrast. However, exposure to trait-implying sentences that described actors with real names and were accompanied with photos of the actors resulted in contrast under both memorization and impression instructions (Experiment 1). Furthermore, contrast ensued when trait-implying sentences were accompanied with information that suggested a person attribution, whereas assimilation ensued when that information suggested a situation attribution, independent of processing goals (Experiment 2). These findings are interpreted as support for referent-based explanations of the consequences of trait inferences. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The effect of processing conditions on glucosinolates in cruciferous vegetables

Summary Glucosinolates are found naturally in cruciferous plants, such asbrassica vegetables, which are important in the human diet. Glucosinolates are readily converted into a range of physiologically active compounds by hydrolysis under the influence of an endogenous thioglucosidase, which becomes active when plant cells are disrupted. Cruciferous vegetables are eaten raw, they are also consumed in the processed form. The influence of processing conditions on glucosinolate degradation and on the type and levels of the reaction products formed is reviewed.

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Der Einfluß von Prozeßbedingungen auf Glucosinolate in Cruciferen-Gemüse

Zusammenfassung Glucosinolate kommen naturgemäß in Kreuzblütlern vor, wie z. B. inBrassica-Gemüse, welche einen wesentlichen Bestandteil der Nahrung bilden. Glucosinolate werden leicht umgesetzt in eine Reihe physiologisch aktiver Verbindungen unter Einfluß einer endogenen Thioglucosidase, welche aktiv wird, wenn das pflanzliche Gewebe zerstört wird. Die Cruciferen-Gemüse werden roh, aber auch in verarbeiteter Form, gegessen. Der Einfluß der Verarbeitung auf den Abbau der Glucosinolate, sowie auf Art und Menge der gebildeten Reaktionssprodukte, wird besprochen.

     

Fundamental aspects of energy conservation policy

The formulation of a governmental energy conservation policy requires that the issues involved be fundamentally analyzed. Information transfer, more intensive use of data, and good housekeeping can all contribute to reduced energy use. Our major choice, however, is between producing the present mix of materials, commodities, and services more efficiently or decreasing demand for them. The first option is referred to as the “technical fix”, the second one as “change of lifestyle”. If the first option fails, changes in life-style might become mandatory.This paper deals with the technical fix approach. Higher capital investment can lead to a decrease in direct use of energy. Both the cost and the energy involved in these investments are analyzed along a conservation path, and a limited number of constants is used to describe the changes along this path. These constants can also be used to feed technological information into macroeconomic analysis.The time scales involved pose the major problem to achieving conservation by means of a technological fix. An increase in the price of energy will lead to higher capital investments in accordance with the economic lifecycles in the different sectors. For applications with a short life-time, such as in the transport sector, energy conservation will mainly take place through the construction of new equipment. In sectors with long lifetime investments (e.g. buildings), retrofitting will be important.Including the indirect energy requirements in the conservation study leads to some important conclusions. It can be demonstrated that the thermodynamic limit is not the ultimate limit for conservation. An energy minimum is obtained, which corresponds to a use of energy higher than the thermodynamic limit. It is also impossible to reduce or eliminate some components of the present energy supply system and at the same time to introduce a new decentralized supply system.A crucial aspect of the technological fix approach is that within the present rules, capital investments for saving direct energy can only be made after the increase in energy price has taken place or when it can be firmly anticipated on a short term. At this point, however, the time needed for making these capital investments is lacking and adverse economic consequences can be expected.It is therefore the major task of governmental policy to induce conservation before it is economically acceptable or possible. This requires some form of government interaction. The theory developed in this paper provides a method by which to rank the options according to the energy saved per dollar of public funds invested. This measures the difference between the objectives of the private sector and those of society.The longer this policy is postponed, the larger is the risk that conservation will have to be achieved in an emergency program. In that situation the indirect energy necessary for the capital construction might jeopardize the short-term goals.     

Engineering Technology, and the University

The historically unprecedented interpenetration of the human, societal, and technological spheres has created a theoretical and intellectual challenge for engineering and the university as a whole. A greater interdependence between the social sciences and humanities on the one hand, and the professional, applied science, and engineering on the other, continues to be an urgent problem. Engineering education can make a decisive contribution by developing a complementary science that will relate to the social sciences and humanities the way the applied sciences relate to the natural sciences. A similar approach may be taken by other sectors of the university, permitting them to remain vital in a technological age.     

Supertankers: Simulators for the study of steering.

Reports on the development of simulators for the study of supertankers, one of the largest man-machine systems ever built. Since the law requires that they be steered by hand in critical conditions (e.g., entering a harbor), supertankers offer an opportunity to study various aspects of human performance as controllers of complex systems. Limitations of the simulators and experimental applications are examined. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

海牙城市设计：新旧城市设计项目中蕴含的持久价值

城市设计项目对判别和界定当代城市的构成和特性十分重要。因为城市设计的跨学科属性,其实践活动的运作须在建筑科学规律与设计定位、城市规划的政策制定以及其他诸如交通工程等相关学科之间取得平衡。对西方后工业化城市而言,城市经济与建成环境相关的新感知和经验联系的产生日益密切。因此,当谋划具备承载力、竞争力、可塑性以及充满社会活力的城市时,