Aktuelle Aspekte der Eisenbahnbetriebsführung — das Betriebsführungssystem ALINET von Alcatel

Liberalization of the European railway transport system and the thus obliged discrimination-free entry to the railway network create new basic conditions for railway operational traffic management. State-of-the-art signaling and train control systems standardized Europe-wide are the basis for a maximum amount of safety and reliability. With ALINET, the extensive management operational system of Alcatel, a corresponding platform is available for the optimized traffic control of railway infrastructure.     

Downstream natural gas in Europe—High hopes dashed for upstream oil and gas companies

Access for independents to retail gas markets was a central concern in European policy reform efforts in the 1990s. Upstream oil and gas companies reacted with strategic intentions of forward integration. By late 2004, forward integration was still weak, however. An important explanation of the gap between announced strategic re-orientation and actual strategy implementation lies in the political failure of EU member states to dismantle market barriers to entry for independents. Variations between companies in downstream strategy implementation are explained by variations in business opportunities and internal company factors.     

Availability, reliability and downtime of systems with repairable components

Closed-form expressions are derived for the steady-state availability, mean rate of failure, mean duration of downtime and lower bound reliability of a general system with randomly and independently failing repairable components. Component failures are assumed to be homogeneous Poisson events in time and repair durations are assumed to be exponentially distributed. The results are expressed in terms of the mean rates of failure and mean durations of repair of the individual components. Closed-form expressions are also derived for the rates of change of the various probabilistic system performance measures with respect to the mean rate of failure and the mean duration of repair of each component. These expressions provide a convenient framework for identifying important components within the system and for decision-making aimed at upgrading the system availability or reliability, or reducing the mean duration of system downtime. Example applications to an electrical substation system demonstrate the use of the formulas developed in the paper.     

In situ, high-pressure differential thermal analysis and ionic conductance of PMMA-based gels with and without TiO2 nano-particle filler

The transition behaviours of PMMA-based gels with and without nano-particle filler have been investigated at elevated pressures up to 0.9 GPa and in the temperature range 220-310 K. Both gels had molar ratios of 53.9:22:5.2:18.9 of ethylene carbonate (EC), propylene carbonate (PC), lithium perchlorate, PMMA, and one gel contained 8 wt.% TiO₂ nano-particles. The results show a sluggish transition between a low-pressure (high temperature) state and a high-pressure (low temperature) state. The nano-particle filler facilitates the kinetics of the transition, yielding a significantly lower transition pressure as well as a better homogeneity in the sample after a transition back to the low-pressure state. These results can be explained by a filler-induced increase of the nucleation rate, which yields smaller crystallites. The transition is observed also by differential scanning calorimetry and Raman spectroscopy at ambient pressure and is likely associated with crystallization of the EC-PC solvent. The logarithmic pressure derivative of the conductance and, consequently, the activation volume changes a factor of 3 as a result of the transition.     

用于过流保护的薄膜电阻技术

电子电路中的电源意外可分成两大类:过流风险和过压风险。过流情况通常是由过载或短路引起的,而过压情况通常是由闪电或切换感性负载造成的快速瞬态电压引起的。     

Sorption Equilibrium in Relation to the Spatial Distribution of Molecules — Application to Desorption of Potato

ABSTRACT

An analysis of desorption isotherms for potato shows the following probable qualities in the water-potato system. In the natural state the water is bound rather strongly due to loss of rotational degrees of freedom in the sorbed molecules, which is caused by small molecular voids in the cellulose structure. This structure therefore is formed as a uniformly cross bound state of the OH-groups. This state prevails up to a certain temperature, above which a reaction sets in, where OH bonds are successively broken, giving possibility for a partial rotation of sorbed molecules. In the range of lower moisture content the cellulose structure is changed into a crystalline state as in wood, although the degree of crystallinity is lower, which is the probable reason why the statistical fluctuations in the isotherms are greater for potato than for wood.     

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)     

Asymptotic first-passage time distributions in compound poisson processes

First-passage problems for compound Poisson processes appear in reliability investigations concerning damage accumulation in structures that are subject to random process excitations. Asymptotic first-passage time distributions are easily obtained. Their accuracies are studied by use of simulation. Surprisingly good accuracy is achieved.