Does the use of Solar Home Systems (SHS) contribute to climate protection?

The paper addresses planners and decision-makers in the field of international development cooperation and also institutions concerned with the impacts of project- and technology promotion. The primary aim of the dissemination of Solar Home Systems (SHS) in off grid areas in developing countries is to improve the living conditions of the population in a cost–effective manner. A large-scale dissemination is essential both for significant contributions to development and for climate effectiveness. However, the contribution of SHS to climate protection is disputed. This analysis presents the most important parameters affecting the contribution of SHS to climate protection and quantifies the influence of those parameters. The case considered presupposes the commercial dissemination of SHS. Greenhouse gas (GHG) emissions are affected by the marketing decisions of the supplier of SHS. With regard to the impact on GHG emissions, a comparison is made between traditional lighting with petroleum lamps and the use of dry cell batteries to operate small devices (baseline case) on the one hand and SHSs on the other. The comparison shows GHG savings of around 9 tonnes of CO₂ equivalent GHG emissions within a 20-year period of use of one single 50 Wp SHS compared with the baseline case. The result is robust with respect to variations in GHG-affecting variables. Petroleum consumption and dry cell batteries dominate GHG emissions balances to such an extent that scarcely any importance can be attached to GHG emissions from the transportation and manufacture of SHS. Therefore, it is permissible to use simplified GHG inventories which ignore the GHG emissions arising from the transportation and manufacture of SHS. Therefore the conclusion is, if SHS are commercially disseminated and used cost efficiently to substitute kerosene and dry cell batteries they reduce GHG emissions effectively. In that case SHS can make a significant contribution to climate protection by the dissemination of large numbers.     

Forced convection subcooled boiling of binary mixtures

A mode based on an additive mechanism of heat transfer is proposed for forced convection subcooled boiling of binary mixtures. The contributing modes of heat transfer are: (i) the heat transferred as latent heat by the rising bubbles, (ii) the heat transferred as the heat contained in the superheated thermal layer that is removed from the surface in the wake of the rising bubbles and (iii) the single phase forced convection heat transfer from the heating surface not influenced by the bubbles. Experimental data from the literature on binary systems show good agreement with the model, validating the postulated mechanism.     

Mechanoluminescent pulse pressure sensors. Processing of output optical signal

The process of mechanoluminescence transformation of a pulse pressure sensor is considered. The process consists in excitation of emission under the action of mechanical loading. An algorithm for use in processing the output optical signal of the sensor that makes it possible to determine an input shock pulse is presented. __________ Translated from Izmeritel’naya Tekhnika, No. 10, pp. 28–31, October, 2007.     

Development of ultra light magnesium-lithium alloys

Magnesium-lithium alloys are among the lowest density metallic materials. Addition of lithium, with a relative density of 0·53, in magnesium reduces the density of the alloy significantly. Furthermore, addition of nearly 11 wt.% lithium converts hexagonal close packed structure of pure magnesium to a body centered cubic lattice, markedly improving formability of the alloy. The development of these alloys, however, had been hampered due to the high reactivity of lithium and magnesium in the molten state and also, due to poor creep resistance and instability of mechanical properties at room temperature. In an attempt to indigenize these ultra light alloys for possible applications in Indian satellite programme, detailed research work was initiated in DMRL. The difficulties associated with producing sound cast ingots have been overcome by controlling melting and casting parameters of these alloys. Extensive work has been done on structure-property correlation of alloys with varying lithium content and minor alloying additions. Based on these work, advanced magnesium-lithium alloys have been developed with improved tensile properties, room temperature stability and creep resistance. Wrought products (plates/sheets) of magnesium-lithium alloy have been supplied to ISAC, Bangalore and are being used in their INSAT-2 programme. This paper describes the systematic studies carried out in the laboratory to indigenize these ultra light alloys.     

Dislocations and flux pinning in YBa2Cu3O7

The dislocation structures of bulk textured and epitaxial thin film YBa₂Cu₃O₇ superconductors are examined. Correlations between increases in flux pinning and dislocation densities are noted. A model for flux pinning by individual dislocations is presented. This gives a treatment of strain induced effects and effects of normal state region interactions. It is shown that the values of pinning predicted are in line with experimental observations.     

Evaluation of influence of external magnetic disturbance on superconducting magnet taking conservation of linkage flux into account

External magnetic disturbance influences the quality of the image obtained with a magnetic resonance imaging (MRI) system because it causes magnetic resonance frequency drift. When a superconducting magnet in persistent current mode operation is exposed to external magnetic disturbance coil current varies to keep linkage flux constant. Conventional analysis is usually formulated with constant current and does not provide correct evaluation of drift of magnetic field in the magnet. This paper proposes a method of numerical analysis of magnetic field considering conservation of linkage flux in a superconducting magnet under a persistent current mode operation. This method is applied to evaluate drift of the magnetic field in a superconducting magnet for magnetic resonance imaging due to external magnetic disturbance. Analysis results show good agreement with the experimental results.     

求解电缆自感系数的一个佯谬

用求自感系数的两个常用公式求解实心电缆自感系数时，如果不注意对公式中Φm及I的正确理解，将会得到不一致的“佯谬”结果。本文通过将实心电缆等效为许多细线圈的方法，用2种公式求解得到了一致的结果。     

氧气顶吹转炉吹炼过程动态模型

通过炉气流量和成分的在线采样信息，用积分法计算熔池排出碳量，并根据熔炼体系中碳的守恒，动态推算熔池含碳量，由此来预报吹炼终点。较深入研究了提高炉气流量检测精度的方法，如心平衡修正和钢液成分反馈修正等，并采用了滤波算法，这些措施有利于提高动态模型的精度。     

Flammability characteristics at applied heat flux levels up to 200 kW/m2

This paper documents the first of the two interrelated studies that were conducted to more fundamentally understand the scalability of flame heat flux, the motivation being that it has been reported that flame heat flux back to the burning surface in bench‐scale experiments is not the same as for large‐scale fires. The key aspect was the use of real scale applied heat flux up to 200kW/m² which is well beyond that typically considered in contemporary testing. The main conclusions are that decomposition kinetics needs to be included in the study of ignition and the energy balance for steady burning is too simplistic to represent the physics occurring. An unexpected non‐linear trend is observed in the typical plotting methods currently used in fire protection engineering for ignition and mass loss flux data for several materials tested and this non‐linearity is a true material response. Using measured temperature profiles in the condensed phase shows that viewing ignition as an inert material process is inaccurate at predicting the surface temperature at higher heat fluxes. The steady burning temperature profiles appear to be invariant with applied heat flux. This possible inaccuracy was investigated by obtaining the heat of gasification via the ‘typical technique’ using the mass loss flux data and comparing it to the commonly considered ‘fundamental’ value obtained from differential scanning calorimetry measurements. This comparison suggests that the ‘typical technique’ energy balance is too simplified to represent the physics occurring for any range of applied heat flux. Observed bubbling and melting phenomena provide a possible direction of study. Copyright © 2007 John Wiley & Sons, Ltd.