面向内存文件系统的数据一致性更新机制研究

近年来,研究界提出了多种管理新型存储级内存的内存文件系统,例如BPFS,PMFS和SIMFS。由于内存文件系统的设备访问方式和I/O路径不同于传统面向块设备的文件系统,适用于内存文件系统的数据一致性更新机制尚未得到很好的研究。为此,提出一种适用于内存文件系统的直接拷贝的数据一致性更新机制,讨论多种数据一致性更新机制在内存文件系统中的优缺点,并以内存文件系统SIMFS为基础,实现多种支持不同数据一致性更新机制的SIMFS版本。通过测试基准测试了各个SIMFS版本的性能,并分析了不同数据一致性更新机制对内存文件系统的整体性能的影响。实验结果表明,提出的直接拷贝机制在内存文件系统中取得了最好的性能。     

Group codes on certain algebraic curves with many rational points

We construct a series of algebraic geometric codes using a class of curves which have many rational points. We obtain codes of lengthq ² over _q , whereq = 2q ₀ ² andq ₀ = 2 ⁿ , such that dimension + minimal distance q ² + 1 – q ₀ (q – 1). The codes are ideals in the group algebra _q [S], whereS is a Sylow-2-subgroup of orderq ² of the Suzuki-group of orderq ² (q ² + 1)(q – 1). The curves used for construction have in relation to their genera the maximal number of GF _q -rational points. This maximal number is determined by the explicit formulas of Weil and is effectively smaller than the Hasse—Weil bound.Supported by Deutsche Forschungsgemeinschaft while visiting Essen University     

Size distributions of nanoscaled particles and gas temperatures from time-resolved laser-induced-incandescence measurements

Laser-induced-incandescence (LII) signal decays are measured in sooting premixed atmospheric and low-pressure flames. Soot particle temperatures are obtained from LII signals measured at two wavelengths. Soot particle size distributions P(r) and flame temperatures T are measured spatially resolved by independent techniques. Heat and mass transfer kinetics of the LII process are determined from measured soot particle temperatures, flame temperatures, and particle sizes. Uncertainties of current LII models are attributed to processes during the absorption of the laser pulse. Implications for LII experiments are made in order to obtain primary soot particle sizes. Soot particle size distributions and flame temperatures are assessed from measured particle temperature decays by use of multi-D nonlinear regression.     

Investigation of Electrode Electrochemical Reactions in CH3NH3PbBr3 Perovskite Single‐Crystal Field‐Effect Transistors

Optoelectronic devices based on metal halide perovskites, including solar cells and light‐emitting diodes, have attracted tremendous research attention globally in the last decade. Due to their potential to achieve high carrier mobilities, organic–inorganic hybrid perovskite materials can enable high‐performance, solution‐processed field‐effect transistors (FETs) for next‐generation, low‐cost, flexible electronic circuits and displays. However, the performance of perovskite FETs is hampered predominantly by device instabilities, whose origin remains poorly understood. Here, perovskite single‐crystal FETs based on methylammonium lead bromide are studied and device instabilities due to electrochemical reactions at the interface between the perovskite and gold source–drain top contacts are investigated. Despite forming the contacts by a gentle, soft lamination method, evidence is found that even at such “ideal” interfaces, a defective, intermixed layer is formed at the interface upon biasing of the device. Using a bottom‐contact, bottom‐gate architecture, it is shown that it is possible to minimize such a reaction through a chemical modification of the electrodes, and this enables fabrication of perovskite single‐crystal FETs with high mobility of up to ≈15 cm² V^?1 s^?1 at 80 K. This work addresses one of the key challenges toward the realization of high‐performance solution‐processed perovskite FETs.     

优化乙醇和食糖混合生产过程

新型控制系统平台帮助糖类产品生产商,根据变化的市场需要,最优化食用糖和纯乙醇的混合生产过程。     

Measuring strain distributions in amorphous materials.

A number of properties of amorphous materials including fatigue, fracture and component performance are governed by the magnitude of strain fields around inhomogeneities such as inclusions, voids and cracks. At present, localized strain information is only available from surface probes such as optical or electron microscopy. This is unfortunate because surface and bulk characteristics in general differ. Hence, to a large extent, the assessment of strain distributions relies on untested models. Here we present a universal diffraction method for characterizing bulk stress and strain fields in amorphous materials and demonstrate its efficacy by work on a material of current interest in materials engineering: a bulk metallic glass. The macroscopic response is shown to be less stiff than the atomic next-neighbour bonds because of structural rearrangements at the scale of 4-10 A. The method is also applicable to composites comprising an amorphous matrix and crystalline inclusions.     

Einsatz von Entspannungsturbinen in CO2-Laseranlagen

Zusammenfassung Im Resonator von Laseranlagen werden ca. 20% der zugeführten Energie für den Laserstrahl genutzt. 80% der zugeführten Gesamtenergie werden mit dem Lasergas ungenutzt aus dem Resonator in den nachfolgenden W?rmeübertrager abgeführt. Um den Anlagenwirkungsgrad von Laseranlagen zu erh?hen, soll die ungenutzte Austrittsenergie aus dem Resonator in einer nachgeschalteten Entspannungsturbine in mechanische Energie umgesetzt werden, die zum Antrieb des Lasergasverdichters genutzt wird. Dadurch kann der Verdichter mit der vorhandenen Proze?energie angetrieben werden und der Anlagenwirkungsgrad vonη _A bis 0,20 aufη _A bis 0,34 erh?ht werden. Durch thermodynamische Proze?untersuchungen werden die erreichbaren Wirkungsgradsteigerungen von Laseranlagen ausgewiesen und die optimalen Parameterbereiche für die Druck-und Temperaturverh?ltnisse ermittelt. Das Leistungsverh?ltnis der gewonnenen Turbinenleistung zur notwendigen Verdichterleistung wird angegeben.     

Technofunctional Properties of Films Made From Ethylene Vinyl Acetate/Whey Protein Isolate Compounds

One challenge faced by the plastics industry is that crude oil will become scarcer and more expensive in the future. Furthermore, an increase in plastic waste is leading to a strongly growing demand for sustainable alternatives to traditional, crude oil‐based polymers in the packaging sector. The aim of this study was to investigate the influence of the incorporation of whey protein isolates (WPIs) on the technofunctional properties of ethylene vinyl acetate (EVA) films. The compounding EVA with WPI was conducted in a co‐rotating twin‐screw extruder at varying processing temperatures. WPI and hydrolysed WPI with a degree of hydrolysis of 10% were used up to 35% (w/w) as filler. The tensile strength and elongation at break of the resulting EVA‐based films decreased significantly with increasing filler content. Because of the hydrophilicity of WPI, the water vapour permeability of the films increased. Advantageously, the oxygen barrier was enhanced by 50–80% compared with that of pure EVA films, which offered the potential of using whey proteins as a filler in compounds for packaging materials for their oxygen barrier properties. In addition, this study provides a promising perspective on the thermoplastic processing of whey protein formulations in the future. Copyright © 2013 John Wiley & Sons, Ltd.