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排序方式: 共有7121条查询结果,搜索用时 15 毫秒
31.
Francisco J. Collado Eduardo Sevilla Carlos Valcárcel 《American Institute of Chemical Engineers》2002,48(5):1100-1108
New thermodynamic fundamentals for vertical pneumatic conueying are proposed with derivation based strictly on mass conservation and continuum concept. For a 1-D, vertical, steady gas-solid flow, these new mass and energy balances allowed the derivation of a new nondimensional energy factor containing the pressure drop. This energy factor correlated quite well with the difference between the inlet gas velocity and solids terminal velocity, when tested against high-pressure, 15-m-high, vertical pneumatic transport data from Institute of Gas Technology. The energy factor was also checked against atmospheric-pressure data of the 5-m lift line of the Pennsylvania State Uniuersity. The new energy factor covers quite well both the atmospheric- and high-pressure sets of data (923 tests) including two heights, lean- and dense-phase transports, several pipe diameters, broad and narrow particle-size distributions, and different materials. The dissipation terms in gas-solid flow were also clearly identified. 相似文献
32.
In this work, we present a novel process to produce plasticized PVC articles. Plasticized PVC dispersion resin (dry blend) was extruded and poured into a hot mold. The mold was transferred to a rotomolding machine, where the final geometry was obtained. Formulations using commercial PVC suspension resin and three different types of plasticizers were prepared under different processing conditions. The physical appearance of the articles and the tensile properties of the materials were evaluated. 相似文献
33.
Dipl.-Phys. Andreas Neuber M. Sc. Guenther Carlos Krieger Dipl.-Ing. Markus Tacke Prof. Dr.-Ing Johannes Janicka 《Forschung im Ingenieurwesen》1996,62(7-8):188-194
Zusammenfassung Die laserspektroskopischen Me?methoden laserinduzierte Fluoreszenz und spontane Ramanspektroskopie werden eingesetzt zur Messung
der Konzentrationen von Stickoxid, Hydroxyl sowie der chemischen Hauptkomponenten und der Temperatur. Betrachtet wird die
thermische Umsetzung von Wasserstoff mit Luftsauerstoff. Es wird die experimentelle Vorgehensweise und Problematik dargestellt.
Ebenso wird der Weg der Modellierung und Berechnung turbulenter Verbrennungsvorg?nge am konkreten Beispiel skizziert. Die
Annahme chemischen Gleichgewichts stellt sich als ungenügend in der Berechnung der Stickoxid- und Hydroxylkonzentrationen
heraus. Eine deutlich bessere Vorhersage wird durch Einführen einer Reaktionsfortschrittsvariablen für das chemische Modell
erreicht. 相似文献
34.
A new method is described for thein-situ measurement of electrical resistivity of concrete structures. The method is based on the early work of J. Newman who calculated
the electrolyte resistivity between a disk and a counter electrode located at infinity. This method has the advantage compared
with Wenner's of using a single small electrode for the measurements. In this paper, results are presented comparing this
method with Wenner's and with results carried out using a conductivity cell in electrolytes. Finally, values of resistivity
are compared to corrosion intensity, and a threshold for active corrosion is suggested.
Editorial note Camen Andrade and Maria-Cruz Alonso are working at the Instituto Eduardo de Torroja which is a RILEM Titular Member. Dr. Andrade, who was the 1986 RILEM Medallist, have had all these years great responsibilities within RILEM. Chairlady of the Advisory Technical Committee until 1993, she is now a member of the Coordinating Committee. She is active in 116-PCD Technical Committee on Permeability of Concrete as a Criterion of its Durability and has been appointed chairdlady of 154-EMC Technical Committee on Electrochemical Techniques for Measuring Metallic Corrosion. Carmen Andrade has been appointed RILEM Fellow in 1995. 相似文献
Résumé On décrit une nouvelle méthode de mesure de la résistivité électrique du béton dont la technique est basée sur un travail ancien de J. Newman qui avait calculé la résistivité entre un disque et une électrode auxiliaire placée à l'infini. Comparée à la méthode de Wenner, cette méthode présente l'avantage de n'utiliser, pour les mesures, qu'une petite électrode. Dans cet article, on présente les résultats de la comparaison établie avec la méthode de Wenner et avec les résultats obtenus avec une cellule de conductivité placée dans les électrolytes. Enfin, on compare les valeurs de la résistivité du béton avec celles de l'intensité de la corrosion et on suggère un seuil de corrosion active.
Editorial note Camen Andrade and Maria-Cruz Alonso are working at the Instituto Eduardo de Torroja which is a RILEM Titular Member. Dr. Andrade, who was the 1986 RILEM Medallist, have had all these years great responsibilities within RILEM. Chairlady of the Advisory Technical Committee until 1993, she is now a member of the Coordinating Committee. She is active in 116-PCD Technical Committee on Permeability of Concrete as a Criterion of its Durability and has been appointed chairdlady of 154-EMC Technical Committee on Electrochemical Techniques for Measuring Metallic Corrosion. Carmen Andrade has been appointed RILEM Fellow in 1995. 相似文献
35.
Carlos A. Felippa Bjrn Haugen Carmelo Militello 《International journal for numerical methods in engineering》1995,38(2):199-229
This paper starts a sequence of three articles that follow an unconventional approach in finite element research. The ultimate objective is to construct high-performance elements and element-level error estimators for those elements. The approach takes off from our previous work in high-performance elements and culminates with the development of finite element templates. The present paper concentrates on the patch test and evolved versions of the test that have played a key role in this research. Following a brief review of the historical roots, we present the Individual Element Test (IET) of Bergan and Hanssen in an expanded context that encompasses several important classes of new elements. The relationship of the IET to the multielement forms A, B and C of the patch test and to the single-element test are investigated. An important consequence of the IET application is that the element stiffness equations decompose naturally into basic and higher-order parts. The application of this decomposition to the “sanitization” of the non-convergent BCIZ element is described and verified with numerical experiments. Two sequel papers in preparation are subtitled ‘the algebraic approach’ and ‘element-level error estimation’. These apply the fundamental decomposition to the derivation of templates for specific mechanical elements and to the construction of element-level error estimators, respectively. 相似文献
36.
An overview of FDA medical device regulation as it relates to deep brain stimulation devices. 总被引:1,自引:0,他引:1
Carlos Pe?a Kristen Bowsher Ann Costello Robert De Luca Sara Doll Khan Li Marie Schroeder Theodore Stevens 《IEEE transactions on neural systems and rehabilitation engineering》2007,15(3):421-424
The United States Food and Drug Administration (FDA) is charged with assuring the safety and effectiveness of a variety of medical products and the FDA's Center for Devices and Radiological Health is responsible for premarket and postmarket regulation of medical devices. In this paper, we review--from device classification and clinical studies to the final marketing application--FDA's premarket requirements and postmarket requirements as they relate to deep brain stimulation devices. 相似文献
37.
Proper integration of scheduling and control in Flexible Manufacturing Systems will make available the required level of decision-making capacity to provide a flexibly-automated, efficient, and quality manufacturing process. To achieve this level of integration, the developments in computer technology and sophisticated techniques of artificial intelligence (AI) should be applied to such FMS functions as scheduling. In this paper, we present an Intelligent Scheduling System for FMS under development that makes use of the integration of two AI technologies. These two AI technologies — Neural Networks and Expert Systems — provide the intelligence that the scheduling function requires in order to generate goodschedules within the restrictions imposed by real-time problems. Because the system has the ability to plan ahead and learn, it has a higher probability of success than conventional approaches. The adaptive behavior that will be achieved contribute to the integration of scheduling and control in FMS. 相似文献
38.
39.
Describes radio receivers that monitor transmissions from beacons on geosynchronous satellites. The receivers can detect ionospheric perturbations of a 300-3000 s period in the electron density integrated from beacon to receiver, for amplitudes as low as (1-2)×1013 m-2. Data are used in studies of atmospheric acoustic and acoustic-gravity waves 相似文献
40.
This study, guided in part by G. A. Marlatt and J. R. Gordon's (1985) abstinence violation effect (AVE) model, examined whether variability in cognitive and emotional reactions to binges accounts for recurrence of binge eating. Attributional, cognitive, and affective reactions to 2 successive binges, as well as the latencies between each binge and a subsequent binge, were evaluated through a series of structured phone interviews with 50 nonpurging normal-weight female bingers. Reported mood after binging was unrelated to binge latency. However, when Ss made more intense internal, global, and uncontrollable causal attributions for a binge, a subsequent binge followed significantly sooner. Within-subject variations in AVEs across binges prospectively predicted within-subject variations in the speed with which another binge followed. Analyses suggested that cognitive states (e.g., AVE and guilt) evoked by particular events were better predictors of how quickly binging repeats than were stable differences in attributional style. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献