Photovoltaic characterization of amorphous hydrogenated and chlorinated silicon films

Hydrogenated and chlorinated silicon films were used to deposit Schottky barrier solar cells. Photovoltaic characterization, together with the results of electronic transport measurements, led to the conclusion that the presence of chlorine is detrimental to the properties of this kind of device.     

An efficient heuristic for scheduling batches of parts in a flexible flow system

Flexible manufacturing systems (FMSs) are a class of automated systems that can be used to improve productivity in batch manufacturing. Four stages of decision making have been defined for an FMS—the design, planning, scheduling, and control stages. This research focuses on the planning stage, and specifically in the area of scheduling batches of parts through the system.The literature to date on the FMS planning stage has mostly focused on the machine grouping, tool loading, and parttype selection problems. Our research carries the literature a step further by addressing the problem of scheduling batches of parts. Due to the use of serial-access material-handling systems in many FMSs, the batch-scheduling problem is modeled for a flexible flow system (FFS). This model explicitly accounts for setup times between batches that are dependent on their processing sequence.A heuristic procedure is developed for this batch-scheduling problem—the Maximum Savings (MS) heuristic. The MS heuristic is based upon the savings in time associated with a particular sequence and selecting the one with the maximum savings. It uses a two-phase method, with the savings being calculated in phase I, while a branch-and-bound procedure is employed to seek the best heuristic solution in phase II. Extensive computational results are provided for a wide variety of problems. The results show that the MS heuristic provides good-quality solutions.     

Synthesis and properties of zinc nanoparticles: The role and prospects of radiation chemistry in the development of modern nanotechnology

Zinc-containing nanoparticles stable in the liquid phase are synthesized by the radiation chemical reduction of zinc ions in solutions of inverse micelles. The effects of the absorbed radiation dose and the size of the micelle water pool on the spectral characteristics of samples are studied. The HPLC and electron microscopy results indicate that the composition of nanoparticles synthesized depends on the salt nature. Original Russian Text ? A.A. Revina, E.V. Oksentyuk, A.A. Fenin, 2007, published in Zashchita Metallov, 2007, Vol. 43, No. 6, pp. 613–618.     

浅谈降低电解槽氟化铝单耗的方法

氟化铝是电解生产中十分重要的原料，它对控制电解槽电解质温度，保持电解槽技术条件发挥着重要的作用。但随着电解生产成本的逐渐降低，氟化铝的消耗成为电解生产成本中的一项重要内容。本文就某分厂电解槽氟化铝添加的生产工艺、设备、控制以及管理等方面，提出降低氟化铝单耗的简要方法。     

Performance-Analyse und -Optimierung in der Softwareentwicklung

Nicht-funktionale Anforderungen an ein Softwaresystem beschreiben Aspekte, die nicht direkt die Funktionalit?t, wie sie der Benutzer sieht, betreffen.     

Processing of engineering ceramics with high power CO2 lasers

The hardness and brittleness of high performance engineering ceramics such as zirconia, aluminia, silicon carbide and silicon nitride makes traditional processing very expensive and time consuming. Efforts have been made to cut thick commercial ceramics with a continuous wave CO₂ laser. The results obtained so far are very promising and materials up to 10 mm in thickness have been cut successfully.     

Formation of C4 species in the deactivation of a Pd/SiO2 catalyst during the selective hydrogenation of acetylene

The deactivation characteristics of Pd/SiO₂ in the selective hydrogenation of acetylene were correlated with changes in the amount of the C4 species produced. The amounts of butenes produced changed in parallel with the catalyst activity, indicating that the rate limiting step for butene production was the same as that for acetylene hydrogenation. On the other hand, the amount of 1,3-butadiene produced changed, showing a maximum with catalyst deactivation because 1,3-butadiene is an intermediate in the sequential reaction process which involves both the production and consumption of 1,3-butadiene. This was verified by a simultaneous TG/reaction experiment showing that 1,3-butadiene was a precursor of green oil. The catalyst showed a self-regenerative behavior in its activity and the amounts of C4 species produced during the early stage of deactivation because two opposite factors, which contributed to either the lowering or the promotion of activity, were involved in the process. A specific type of polymer species, produced during the initial period of deactivation, is proposed to be responsible for the promotion of catalyst activity.