Untersuchung überlagerter Effekte von Druckverlust und Totvolumen durch Rekuperation am isobaren Expansionsmotor

The efficiency of heat engines is significantly influenced by heat recovery in recuperators. In the case of the Bush-type isobaric expansion engine (IEE), a heat engine that can be operated with heat sources starting from 60°C, the thermal efficiency increases significantly through the use of recuperators. At the same time, internal fluid volumes of the heat exchanger and the pressure loss arising during operation have a negative effect on the thermal efficiency. In this work, the interaction between dead volume, pressure loss and heat recovery is investigated and recommendations for the operation of recuperators in the isobaric expansion engine are given.     

Aggregation in solutions of poly(γ-benzyl-l-glutamate) monitored by static and dynamic light scattering

We have studied dilute and semidilute solutions of poly(γ-benzyl-l-glutamate) in 1,2-dichloroethane by static and dynamic light scattering. The aggregational behaviour of the semiflexible polymer is evidenced in both static and dynamic scattering, and is sensitive to the temperature and the polypeptide molecular weight. In particular, both the reciprocal specific scattering intensity and the effective decay rate of the dynamic correlations exhibit a minimum as a function of the concentration. The slope of effective diffusion coefficient versus the square of the scattering vector displays an anomalous maximum as a function of the concentration which can also be attributed to aggregation. The experimental evidence is compatible with head-to-tail dimerization of the polymer as the concentration increases.     

Deposition of Refractory Ceramic Fibers (RCF) in the Human Respiratory Tract and Comparison with Rodent Studies

A mathematical model has been developed to calculate the deposition of refractory ceramic fibers (RCF) in the human respiratory tract. For a typical size distribution of airborne RCF found in the work place, the fractional deposition and size distribution of deposited fibers in various regions of the respiratory tract are determined. These results are compared with those obtained earlier in rats and hamsters. The deposition fraction in the human lung is higher consisting of more coarse and long deposited fibers. This is caused by less efficient filtration of RCF in the human extrathoracic airways. Over the same exposure period however, total number of fibers deposited in the pulmonary region of the humans lung is about 5–10 times smaller per gram of lung or 1–2.5 times smaller per unit lung surface area than the rodents, depending upon the mode of breathing.     

Design and optimisation of a (FA)Q-learning-based HTTP adaptive streaming client

In recent years, HTTP (Hypertext Transfer Protocol) adaptive streaming (HAS) has become the de facto standard for adaptive video streaming services. A HAS video consists of multiple segments, encoded at multiple quality levels. State-of-the-art HAS clients employ deterministic heuristics to dynamically adapt the requested quality level based on the perceived network conditions. Current HAS client heuristics are, however, hardwired to fit specific network configurations, making them less flexible to fit a vast range of settings. In this article, a (frequency adjusted) Q-learning HAS client is proposed. In contrast to existing heuristics, the proposed HAS client dynamically learns the optimal behaviour corresponding to the current network environment in order to optimise the quality of experience. Furthermore, the client has been optimised both in terms of global performance and convergence speed. Thorough evaluations show that the proposed client can outperform deterministic algorithms by 11–18% in terms of mean opinion score in a wide range of network configurations.     

Graphene-like film CVD on e-beam exposed SiO2/Si by the pyrolysis of different oxygen-containing precursors

ABSRTACT

We have previously found that pyrolysis of ethanol vapor on charge pre-patterned SiO₂/Si substrate leads to controllable deposition of graphene-like films (GLFs). In this work we aim at the GLFs synthesis from acetone and isopropanol on SiO2/Si exposed to an electron beam with various energies and doses. Electron beam induced charge in 200?nm SiO₂ is determined by the shift of the capacitance-voltage characteristics. Synthesized GLFs are characterized using Raman spectroscopy and atomic force microscopy. It is shown that the thickness of GLF on SiO₂/Si increase together with the preliminary exposure dose and inversely associated with electron energies.     

Manufacturing pharmaceutical granules: Is the granulation end-point a myth?

The moist agglomeration process by high-shear mixing/granulation, i.e. the wet massing, screening and subsequent drying is a wide spread but critical unit operation. Since for decades formulators are looking for the correct “end-point” of this important process, i.e. when do you need to stop massing or stop with the addition of granulating liquid? What is the correct amount of granulating liquid? A similar situation exists in case of the moist agglomeration in fluidized bed equipment. In the latter case the simultaneous drying of the still moist granules have to be taken into account. Recently a science-based virtual equipment simulator could be developed mimicking the granule size evolution in a fluidized bed granulator during the addition of granulating liquid. For the simultaneous drying the Mollier chart is used. With this virtual equipment simulator it is possible to simulate “crash situations”, i.e. by overwetting or by an incorrect use of the parameter setting. However the determination of the “end-point” depends only on the operator, who desires a certain granule size distribution and a well-defined final moisture content of the batch. Thus the existence of a process intrinsic “end-point” has to be questioned. The same situation can be reported in case of high-shear mixing/granulation based on many years of research. In fact nobody could clearly show the existence of an intrinsic “end-point”. However during the continuous addition of a granulating low viscous liquid a sudden increase in power consumption can be measured, which levels off. Such a measurement depends on the formulation and leads to an “early signal” not to the “end-point”. This signal can be used for a tight control of the granulation process and leads to a low batch to batch variability in the final granule size distribution. The latter is the goal of the PAT (Process Analytical Technology) Initiative emphasizing “Quality by Design”.     

A Fully Integrated 0.13 μm CMOS Low-IF DBS Satellite Tuner Using Automatic Signal-Path Gain and Bandwidth Calibration

This paper presents the first low-IF fully integrated receiver for DBS satellite TV applications realized in 0.13 mum CMOS. A wideband ring oscillator based frequency synthesizer having a large frequency step was used to downconvert a cluster of channels to a coarsely defined low-IF frequency, while the second downconversion to baseband was performed in the digital domain. Eliminating the oscillator inductors reduced the parasitic magnetic coupling from the digital core, allowing a single-chip integration of the sensitive tuner and the noisy digital demodulator. A significant die area reduction was achieved by using a single oscillator to cover the entire satellite TV spectrum, while a noise attenuator was cascaded with the PLL loop filter to reduce the equivalent tuning gain. The low-IF architecture allowed a discrete-step AGC that improves both tuner noise and linearity performance. Tuner gain and IF corner frequency were calibrated using replica ring oscillators that are tuned up to the onset of oscillations. The tuner specifications include: 90 dB gain range, 9 dB noise figure at max gain, +25 dBm IIP3 at min gain, 1.3degrms integrated phase noise, les50 dBc spurs, 0.7 W power consumption from dual 1.8/3.3-V supplies, and 1.8times1.2 mm ² die area     

Imperfect repair and lifesaving in heterogeneous populations

In this theoretical paper we generalize the notion of minimal repair to the heterogeneous case, when the lifetime distribution function can be modeled by continuous or a discrete mixture of distributions. The statistical (black box) minimal repair and the minimal repair based on information just before the failure of an object are considered. The corresponding failure (intensity) rate processes are defined and analyzed. Demographic lifesaving model is also considered: each life is saved (cured) with some probability (or equivalently a proportion of individuals who would have died are now resuscitated and given another chance). Those who are saved experience the statistical minimal repair. Both of these models are based on the Poisson or non-homogeneous Poisson processes of underlying events, which allow for considering heterogeneity. We also consider the new model of imperfect repair in the homogeneous case and present generalizations to the heterogeneous setting.     

Spurious consensus and opinion revision: Why might people be more confident in their less accurate judgments?

In the interest of improving their decision making, individuals revise their opinions on the basis of samples of opinions obtained from others. However, such a revision process may lead decision makers to experience greater confidence in their less accurate judgments. The authors theorize that people tend to underestimate the informative value of independently drawn opinions, if these appear to conflict with one another, yet place some confidence even in the spurious consensus, which may arise when opinions are sampled interdependently. The experimental task involved people's revision of their opinions (caloric estimates of foods) on the basis of advice. The method of sampling the advisory opinions (independent or interdependent) was the main factor. The results reveal a dissociation between confidence and accuracy. A theoretical underlying mechanism is suggested whereby people attend to consensus (consistency) cues at the expense of information on interdependence. Implications for belief updating and for individual and group decisions are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)