Evaluation of metal hydride machines for heat pumping and cooling applications: Evaluation des machines à hydrure métallique dans les applications de pompes à chaleur et de refroidissement

Three different schemes of metal hydride solid sorption devices for heat pumping and cooling applications are presented and compared based on theoretical evaluations. Key parameters obtained from experimental and simulation results from coupled metal hydride reaction beds have been used for the theoretical evaluation. The single (HS) and double stage (HD) devices show reasonable performances, but they require many moving parts. Using high performance reaction beds, e.g. a capillary tube bundle reaction bed, cycle times of about 5–10 min can be obtained with these devices. This corresponds to a specific power output of 100–200 W kg⁻¹ (HS) or 150–300 W kg⁻¹ (HD), referred to the total hydride inventory of the machine. The multi-hydride-thermal-wave (HW) system has a lower specific power output, but it offers significant advantages like modest hardware effort, low pumping power and a very wide operating temperature range.     

Personnel planning in concurrent engineering: A case study

Personnel planning is traditionally one of the last activities in the process of bringing a product to the market. This can lead to a lack of necessary knowledge, skills, and abilities (KSA) on the shop floor often causing delays at the start of production. In Concurrent Engineering (CE), planning activities are integrated and information is frequently exchanged to avoid such problems. As job design determines the requirements for personnel planning, this article presents a method for integrating job design and personnel planning. This method makes it possible to define personnel requirements in early phases as well as designing jobs to the availability of personnel. It is based on a tool for modeling the task structure in the early phases, when information is still poorly defined, continuously adapting the task model to increasing levels of detail, and a method of directly deducing from the task structure the necessary KSA. The method is well suited to deal with poorly defined information; it allows the design of jobs, and considers personnel selection, education, and training concurrently to other planning activities. A case study is presented to demonstrate its use. © 2000 John Wiley & Sons, Inc.     

Iminium Salts in Solid‐State Syntheses Giving 100% Yield

Numerous reaction types in the field of iminium salts are performed in the gas‐solid and solid‐solid techniques in order to reach 100% yield. The stoichiometric runs are waste‐free and do not require costly workup. Frequently, iminium salts were avoided, as acid catalysis was dispensable. Thioureas and α‐halogenated ketones give a variety of 2‐aminothiazoles via thiuronium salts in quantitative yield. A new intramolecular solid‐state thermal condensation is reported. Enaminoketones are synthesized quantitatively from anilines and 1,3‐diketones without catalysis and those can be used for quantitative solid‐state 4‐cascade reactions. Solid paraformaldehyde is used to produce methylene imines and internally trapped methylene iminium salts. Benzoylhydrazones are produced again without catalysis in the solid state. Vacuum and ball‐mill techniques are particularly useful in the production of highly sensitive iminium salts. Hexahydro‐1,3,5‐triazines cyclorevert upon exposure to HCl gas to give solid arylmethylene iminium chlorides as new versatile reagents. These are used in arylaminomethylations of β‐naphthol and of themselves to give Troeger's bases in 3‐cascades. More direct are 4‐cascade Troeger's base syntheses by dissolving hexahydro‐1,3,5‐triaryltriazines in trifluoroacetic acid. Alkylations of imines with trimethyloxonium tetrafluoroborate and triphenylmethyl cation give highly sensitive quaternary iminium salts in the ball‐mill. The products are characterized by spectroscopic techniques and density functional theory (DFT) calculations at the B3LYP 6‐31G* level. Molecular movements in the crystal and surface passivation are investigated with atomic force microscopy (AFM) techniques.     

Under bump metallurgy study for Pb-free bumping

The demand for Pb-free and high-density interconnection technology is rapidly growing. The electroplating-bumping method is a good approach to meet finepitch requirements, especially for high-volume production, because to volume change of patterned-solder bumps during reflow is not so large compared with the stencil-printing method. This paper proposes a Sn/3.5 Ag Pb-free electroplating-bumping process for high-density Pb-free interconnects. It was found that a plated Sn/Ag bump becomes Sn/Ag/Cu by reflowing when Cu containing under bump metallurgy (UBM) is used. Another important issue for future flip-chip interconnects is to optimize the UBM system for high-density and Pb-free solder bumps. In this work, four UBM systems, sputtered TiW 0.2 μm/Cu 0.3 μm/electroplated Cu 5 μm, sputtered Cr 0.15 μm/Cr-Cu 0.3 μm/Cu 0.8 μm, sputtered NiV 0.2 μm/Cu 0.8 μm, and sputtered TiW 0.2 μm/NiV 0.8 μm, were investigated for interfacial reaction with electroplated Pb/63Sn and Sn/3.5Ag solder bumps. Both Cu-Sn and Ni-Sn intermetallic compound (IMC) growth were observed to spall-off from the UBM/solder interface when the solder-wettable layer is consumed during a liquid-state “reflow” process. This IMC-spalling mechanism differed depending on the barrier layer material.     

Open systems interconnection: the session service

The paper is similar, in content and organization, to the ISO standard documents on layer service specifications. A model for service specifications is described and discussed.     

Operation conditions of batteries in PV applications

For a continuous energy supply of photovoltaic operated and off-grid loads, the storage of the solar generated electrical energy is necessary. About 60% of all over the world manufactured solar cells are used for such stand alone systems. In case of photovoltaic systems, mainly electrochemical battery storage systems are used.

The paper describes the requirements for batteries in solar systems. The most important storage systems, such as lead–acid, NiMH and Li-ion batteries are described in detail and further developing trends are discussed.

As it is well known that the operation conditions strongly influence the battery lifetime, this paper reviews photovoltaic operation conditions and experience in performance and lifetime in photovoltaic systems.     

International cooperation and high-performance reduction in Siberia

In 1989, a cooperative agreement between German and Russian partners was signed, calling for the joint development and construction of a high performance 300 kA reduction cell. The original plan was to install six cells in an existing pilot potroom within the Sayansk Aluminium Smelter at Sayanogorsk, Russia. The cell design was based on detailed computer simulations, covering all important parameters that influence smooth and efficient pot operation. In January 1993, the new 300 kA cells were started up. Their technical performance has been excellent, with remarkable cell stability, productivity, and low energy consumption.