摘要:

AbstractThe paper addresses the design of two‐level power system stabilizers using an optimal reduced order model whose state variables are torque angles and speeds. The reduced order model retains their physical meaning and is used to design a two‐level linear feedback controller that takes into account the realities and constraints of electrical power systems. The two‐level control strategy is used, and a global control signal is generated from the output variables to minimize the effect of interactions. The effectiveness of this controller is evaluated and a multimachine system is given as an example to illustrate the advantages of the proposed method. Responses of the system with a two‐level scheme and an optimal reduced order scheme are included for comparative a

ISSN:0363-907X    

DOI:10.1002/er.4440160202

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractBy proper passive design concepts which essentially consist of collection, storage, distribution, and control of thermal energy flow, an energy saving of 2.35% of the world energy output is possible. The basic methods of heating and cooling of buildings are solar radiation, outgoing longwave radiation, water evaporation, and nocturnal radiation cooling. A Trombe‐Michel wall consists of a large concrete mass, exposed to sunlight through large, south‐facing windows; it is used for heating buildings. Solar absorption cooling and solar dehumidification and evaporative cooling are two approaches that utilize solar energy for the generation of the working fluid and the cooling of dwellings. Outgoing longwave radiation is the most practical way of cooling buildings in desert climates and is effective on roof surfaces, emitting the radiations from the surface of earth to the atmosphere and to outer space. Water evaporation in desert coolers is the usual method of cooling in arid regions. Nocturnal radiation both heats in winter and cools in summer, in suitable climates, and does so with no nonrenewable energy other than a negligible amount required to move the insulation twice a day. The study of 24 different locations in Libya divides the country into regions with distinct passive strategies. The northern region and the Mediterranean coast need passive heating. The buildings in this region should restrict conductive heat flow, prevent infiltration and promote solar heat gains. The southern region, a part of the Sahara desert, needs passive cooling. The buildings in this region need high thermal mass and should promote natural ventilation, restrict solar heat gains and encourage evaporative and radiant cooling. The difficulties encountered in passive solar design are the large exposed area required with suitable orientation for the collection of energy and the large space requirement for the storage of thermal energy. This paper reviews these passive systems and discusses suitable strategies to be adopted for Li

ISSN:0363-907X    

DOI:10.1002/er.4440160203

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractA combined linear programming model for three important end uses, namely cooking, irrigation pumping, and lighting, in rural areas of India, is described. The results of the solution of the combined model are presented. A brief comparison of these results with the results of the individual submodels is also discussed.

ISSN:0363-907X    

DOI:10.1002/er.4440160204

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractThis study investigates the increase in the relative importance of diesel fuel in terms of aggregate farm energy consumption over the 1971–1989 period coupled with the decline in the absolute quantity of diesel fuel consumed over the 1978–1989 period in the USA. Four factors are identified as being central to the observed trend. These include the relative efficiency of diesel‐powered equipment versus gasoline‐powered equipment, the technological changes in dieselpowered equipment that have impacted energy efficiency, the trend towards larger farms, and the enhanced energy conservation by farmers as a result of the adoption of reduced tillage pr

ISSN:0363-907X    

DOI:10.1002/er.4440160205

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractThe paper is an extension to another paper recently published in this same journal by Harvie (1990a). In that paper he developed a simple model to try to identify the possible macroeconomic adjustment processes arising in an economy experiencing a temporary period of oil production, under alternative wage adjustment assumptions, namely nominal and real wage rigidity. Certain assumptions were made regarding the characteristics of actual oil production, the permanent revenues generated from that oil production, and the net exports/imports of oil. The role of the price of oil, and possible changes in that price, was essentially ignored, which was equivalent there to setting it to a value of zero. Hence Harvie (1990a) was effectively concerned with analysing the economic effects arising from the production of oil alone.Here we attempt to overcome this deficiency by incorporating the price of oil, as well as changes in that price, in conjunction with the production of oil, the objective being to identify the contribution which the price of oil, and changes in it, make to the adjustment process itself.As in Harvie (1990a), the emphasis in this paper is not given to a mathematical derivation and analysis of the model's dynamics of adjustment or its comparative statics. But rather to the derivation of simulation results from the model, for a specific assumed case, using a numerical algorithm program, conducive to the type of theoretical framework utilized here.The results presented suggest that although the adjustment profiles of the macroeconomic variables of interest, for either wage adjustment assumption, remain fundamentally the same, the magnitude of these adjustments is increased. Hence, to derive a more accurate picture of the dimensions of adjustment of these macroeconomic variables, it is essential to include the price of oil as well as changes in that price.

ISSN:0363-907X    

DOI:10.1002/er.4440160206

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractThis paper extends the results presented by Harvie (1990) and Harvie and Maleka (1991), using a similar theoretical and simulation framework to analyse the macroeconomic adjustment processes arising for an economy experiencing a temporary period of oil production. Similar assumptions to those in the aforementioned papers, regarding actual oil production, permanent oil revenues and the net export/import of oil, as well as to developments in the price of that oil under alternative wage adjustment assumptions are made.Here, however, emphasis is placed on developments in the current account, as reflected in foreign asset stock movements, after oil production ceases, as well as on the role that monetary, fiscal or fiscal/monetary policy can play in influencing current‐account developments during this same period. Both Harvie (1990) and Harvie and Maleka (1991) conclude that, after a period of temporary oil production, the current account is likely to deteriorate. It is the contention here that the authorities will be concerned with such a potential development, and in the role which fiscal and/or monetary policy can play in alleviating such an effect.The results presented suggest that, to improve the performance of the current account, irrespective of the wage adjustment mechanism operative, after oil production ceases, the major thrust of macroeconomic policy should operate through fiscal rather than monetary policy. However developments in non‐oil output would be influenced by the wage adjustment mechanism. With wage indexation, a tight fiscal policy after oil production ceases leads to a higher level of non‐oil output than in the no policy response case, or one where monetary policy alone is used. With no wage indexation, the use of monetary and/or fiscal policy leads to lower levels of non‐oil output. Hence the extent of wage indexation is important for this latter variable. The use of fiscal policy also has the added benefit of contributing to a lower consumer price level, again irrespective of the operative wage adjustment mechanism.If the emphasis of policy operates through monetary policy this paper suggests that, irrespective of the wage adjustment mechanism, the current‐account problem will be exacerbated since foreign assets stocks will be lower. In addition, non‐oil output and consumer prices will be lower.Hence potentially important policy prescriptions regarding the operation of fiscal and/or monetary policy for an economy after a temporary period of oil production, can be derived from

ISSN:0363-907X    

DOI:10.1002/er.4440160207

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractThe paper solves an optimization problem concerning the conditioned minimization of fuel feed rate against a control vector which incorporates both zonal irradiation and the configuration of an adjusting rod system. One starts from a reference core with two irradiation zones of which the first contains 188 channels and for which all control devices and parasitic absorbers are taken into account. The fuel feed rate is minimized subject to four restrictions imposed, namely reactivity to equilibrium, maximum channel and bundle powers and reactivity of an adjusting rod system. The codes FMDP and LPROG are used to solve this problem.

ISSN:0363-907X    

DOI:10.1002/er.4440160208

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

ISSN:0363-907X    

DOI:10.1002/er.4440160209

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

ISSN:0363-907X    

DOI:10.1002/er.4440160201

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY