Endoreversible Thermodynamics: A Tool for Simulating and Comparing Processes of Discrete Systems

Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG geförderten) Allianz- bzw. Nationallizenz frei zugänglich.This publication is with permission of the rights owner freely accessible due to an Alliance licence and a national licence (funded by the DFG, German Research Foundation) respectively.Endoreversible thermodynamics is concerned with reversible sub-systems that are in irreversible interaction with each other. Consequently, endoreversible thermodynamics represents the analogue for discrete systems to the local equilibrium hypothesis in continuum thermodynamics. Here a real cyclic 2-reservoir process is simulated by different endoreversible model processes. Simulation means that the simulating process has the same net heat exchanges, cycle time, power, entropy production, and efficiency as the original one. By introducing process-independent simulation parameters as constraints for the irreversible interaction, a family of comparative endoreversible processes is generated including the simulation of the original process. This procedure allows the process parameters of the family of comparative processes to be compared to those of the original one. The fraction “power of the real process over the maximal power inbetween the comparative family” is introduced as a parameter describing the process excellence

Die Entwicklung und Bewertung von managementunterstützenden Informationssystemen: Eine empirische Anwenderstudie

In dieser Arbeit werden der Entwicklungsprozeß und die damit verbundenen Bewertungen von managementunterstützenden Informationssystemen empirisch untersucht. Es zeigt sich, daß Kontextfaktoren, insbesondere die Initiatoren des Projektes, erheblichen Einfluß auf den Entwicklungsprozeß ausüben. Der Bewertungsprozeß wird in Hinblick auf die benutzten Kriterien, die eingesetzten Methoden und die Zufriedenheit mit der Bewertung analysiert. Dabei können theoretische Überlegungen und frühere empirische Ergebnisse weitgehend bestätigt werden, denen zufolge bei entscheidungsunterstützenden Systemen qualitativen Kriterien größere Bedeutung zukommt und nutzenorientierte Bewertungsmethoden besser geeignet sind.The paper describes the results of an empirical study on the development and evaluation of management support Systems in Germany. Contextual factors like the project initiator are found to have considerable influence on the development process. The evaluation of MSS is analyzed with respect to the criteria and methods employed and the level of satisfaction with the process. The results of previous studies are confirmed: in evaluating decision-oriented Systems, qualitative criteria are considered to be more important, and utility-oriented methods prove more suitable for this kind of evaluation

Lorentz shift measurements in heavily irradiated silicon detectors in high magnetic fields

An external magnetic field exerts a Lorentz force on drifting electric charges inside a silicon strip sensor and thus shifts the cluster position of the collected charge. The shift can be related to the Lorentz angle which is typically a few degrees for holes and a few tens of degrees for electrons in a 4 T magnetic field. The Lorentz angle depends upon magnetic field, electric field inside the sensor and temperature. In this study the sensitivity to radiation for fluences up to 10^16 n/cm^2 has been studied. The Lorentz shift has been measured by inducing ionization with 670 nm red or 1070 nm infrared laser beams injected into the back side of the irradiated silicon sensor operated in magnetic fields up to 8 T. For holes the shift as a function of radiation is increasing, while for electrons it is decreasing and even changes sign. The fact that for irradiated sensors the Lorentz shift for electrons is smaller than for holes, in contrast to the observations in non-irradiated sensors, can be qualitatively explained by the structure of the electric field in irradiated sensors.Comment: Accepted publication for RD09 conference in Proceedings of Scienc

Phase II Study of Vicriviroc versus Efavirenz (both with Zidovudine/Lamivudine) in Treatment-Naive Subjects with HIV-1 Infection

Background. Vicriviroc (VCV) is a CCR5 antagonist with nanomolar activity against human immunodeficiency virus (HIV) replication in vitro and in vivo. We report the results of a phase II dose-finding study of VCV plus dual nucleoside reverse-transcriptase inhibitors (NRTIs) in the treatment-naive HIV-1-infected subjects. Methods. This study was a randomized, double-blind, placebo-controlled trial that began with a 14-day comparison of 3 dosages of VCV with placebo in treatment-naive subjects infected with CCR5-using HIV-1. After 14 days of monotherapy, lamivudine/zidovudine was added to the VCV arms; subjects receiving placebo were treated with efavirenz and lamivudine/zidovudine; the planned treatment duration was 48 weeks. Results. Ninety-two subjects enrolled. After 14 days of once-daily monotherapy, the mean viral loads decreased from baseline values by 0.07 log10 copies/mL in the placebo arm, 0.93 log10 copies/mL in theVCV25 mg arm, 1.18 log10 copies/mL in the VCV 50 mg arm, and 1.34 log10 copies/mL in the VCV 75 mg arm (P < .001 for each VCV arm vs. the placebo arm). The combination-therapy portion of the study was stopped because of increased rates of virologic failure in the VCV 25 mg/day arm (relative hazard [RH], 21.6; 95% confidence interval [CI], 2.8-168.9) and the VCV 50 mg/day arm (RH, 11.7; 95% CI, 1.5-92.9), compared with that in the control arm. Conclusion. VCV administered with dual NRTIs in treatment-naive subjects with HIV-1 infection had increased rates of virologic failure, compared with efavirenz plus dual NRTIs. No treatment-limiting toxicity was observed. Study of higher doses of VCV as part of combination therapy is warrante