A.F Bouhdjar  L. Ayat  AM. Meftah  N. Sengoug  AF. Meftah 《半导体学报》2015,36(1):014002-8

Using a previous model, which was developed to describe the light-induced creation of the defect density in the a-Si:H gap states, we present in this work a numerical modelling of the photodegradation effect in the a-Si:H p-i-n solar cell under continuous illumination. We first considered the simple case of a monochromatic light beam with a wavelength λ between 530-540 nm non uniformly absorbed, then the global standard solar spectrum (AM 1.5) illumination is taken into account. The photodegradation is analysed on the basis of the resulting changes in the free carrier's densities, recombination rate, band structure, electrical potential and field, space charge, and current densities. Changes in the cell's external parameters: the open circuit voltage V_oc, the short circuit current density J_sc, the fill factor FF and the maximum power density P_max are also presented.  相似文献   

    

L. R. Foulds  J. M. Wilson 《Computers & Industrial Engineering》1999,37(4):847-858

We describe a branch and bound algorithm for an assignment problem subject to a special set of side constraints. The problem has application in the design of tool carousels for certain flexible manufacturing systems. The resulting model represents a special case of the restricted facilities layout problem in which it is forbidden to locate any facility in certain zones. The bounds for the algorithm are generated by relaxing the side constraints and using the Hungarian method to solve the resulting assignment problem. Partitioning in a manner similar to subtour elimination for the travelling salesman problem leads to encouraging computational results.  相似文献   

    

P. Clegg  L. Bruciatelli  F. Domingos  R.R. Jones  M. De Donatis  R.W. Wilson 《Computers & Geosciences》2006,32(10):1682-1698

Both the hardware and software available for digital geological mapping (DGM) have advanced considerably in recent years. Mobile computers have become cheaper, lighter, faster and more power efficient. Global Positioning Systems (GPS) have become cheaper, smaller and more accurate, and software specifically designed for geological mapping has become available. These advances have now reached a stage where it is effective to replace traditional paper-based mapping techniques with those employing DGM methodologies. This paper attempts to assess and evaluate two currently available DGM systems for geological outcrop mapping: one based on a Personal Digital Assistant (PDA) running ESRI “ArcPad”, and the second based on a Tablet PC running “Map IT” software. Evaluation was based on field assessment during mapping of a well-exposed coastal section of deformed Carboniferous and Permian rocks at N. Tynemouth in NE England. Prior to the field assessment, several key criteria were identified as essential attributes of an effective DGM system. These criteria were used as the basis for the assessment and evaluation process. Our findings suggest that the main concerns presented by sceptics opposed to DGM have largely been resolved.In general, DGM systems using a Tablet PC were found to be most suitable for a wide range of geological data collection tasks, including detailed outcrop mapping. In contrast, systems based on a PDA, due to small screen and limited processing power, were best suited for more basic mapping and simple data collection tasks. In addition, PDA-based systems can be particularly advantageous for mapping projects in remote regions, in situations where there is a limited power supply or where total weight of equipment is an important consideration.  相似文献   

    

Bhagavathi D.  Olariu S.  Schwing J. L.  Shen W.  Wilson L.  Zhang J. 《Journal of Parallel and Distributed Computing》1995,27(2)

Our contribution is twofold. First, we show that Ω(log n) is a time lower bound on the CREW-PRAM and the mesh with multiple broadcasting for the tasks of computing the perimeter, the area, the diameter, the width, the modality, the smallest-area enclosing rectangle, and the largest-area inscribed triangle of a convex n-gon. We show that the same time lower bound holds for the tasks of detecting whether a convex n-gon lies inside another as well as for computing the maximum distance between two convex n-gons. We obtain our time lower bound results for the CREW-PRAM by using a novel technique involving geometric constructions. These constructions allow us to reduce the well-known OR problem to each of the geometric problems of interest. We then port these time lower bounds to the mesh with multiple broadcasting using simulation results. Our second contribution is to show that the Ω(log n) time lower bound is tight by providing O(log n) time algorithms to solve these problems on a mesh with multiple broadcasting of size n × n. Finally, we show that for two separable convex n-gons P and Q, the task of computing the minimum distance between P and Q can be performed in O(1) time on a mesh with multiple broadcasting of size n × n.  相似文献   

    

P. Wu  S-C. Fang  H.L.W. Nuttle  J.R. Wilson  R.E. King 《International Transactions in Operational Research》1995,2(3):259-272

We apply neural networks to build a metamodel of the relation between key input parameters and output performance measures of a simulated textile spinning plant. We investigate two different neural network estimation algorithms, namely back-propagation and an algorithm incorporating a fuzzy controller for the learning rate. According to our experience, both algorithms are capable of providing high-quality predictions. In addition, results obtained using a fuzzy controller for the learning rate suggest a significant potential for speeding up the training process.  相似文献   

    

P. Stansby  N. Chini  D. Apsley  A. Borthwick  L. Bricheno  J. Horrillo‐Caraballo  M. McCabe  D. Reeve  B.D. Rogers  A. Saulter  A. Scott  C. Wilson  J. Wolf  K. Yan 《Journal of Flood Risk Management》2013,6(3):229-252

An integrated model system is based on downscaling from climate models, to wave climate and continental shelf models for tides and surge, to coastal models for waves and water levels, to beach levels and overtopping of sea defences and inundation. Present operational practice in the UK is described. The model system is applied to the prediction of flooding at Walcott on 9 November 2007. Inundation levels are predicted in reasonable agreement with those at certain residential properties in Walcott as reported by the occupants. The effect of time‐varying and time‐averaged overtopping discharge is considered. Sensitivity of overtopping and inundation to uncertainties in nearshore wave height and water level is analysed, with the greatest sensitivity being to water level. Extreme joint probability analysis is undertaken, showing the event to be close to a 1 in 100‐year event. Finally, the effects of different rates of sea level rise and a climate change scenario are investigated for 2100; the simulations indicate that the return period of the equivalent 2007 event could reduce to less than 2 years with a 0.5m sea level rise.  相似文献   

    

D.J. Duke  I. Herman  T. Rist  M. Wilson   《Computer Standards & Interfaces》1997,18(6-7):525-535

The need for a suitable classification of media types arises for several reasons when building or comparing multimedia systems. Within an Intelligent Multimedia Presentation Systems (IMMPS), it is necessary to formulate and encode design knowledge for decision making on the appropriate medium in which to present information and for the generation of the presentation. It is also required in order to specify interfaces to and between system components which will be employed to run a generated presentation before the user's eyes. This task is reflected in the Standard Reference Model (SRM, see this volume) for IMMPS by the Presentation Display Layer. However, the SRM does not instantiate this layer in detail, but instead refers to the Presentation Environment for Multimedia Objects (PREMO) ISO/IEC standard which provides a reference model for a presentation runtime environment for multimedia. PREMO already contains a set of basic structures, the so-called PREMO Primitive Hierarchy, to describe different media types. Thus the question arises, as to how far the PREMO Primitive Hierarchy could serve as a media classification for the SRM in general. In particular, this would support consistency between the design and presentation layers of the SRM if PREMO were used to instantiate the presentation layer. In the current paper, we first point to a number of typical problems with generating classifications of media types. We then provide a brief introduction to PREMO and its Primitive Hierarchy. Finally, the benefits and costs of using the PREMO Primitive Hierarchy for the SRM are discussed.  相似文献   

    

M E Womble  S D Wilson  H N Keiser  M L Tworek 《Computers and biomedical research》1979,12(5):471-481

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Marc Gravel  Laszlo Kiss  Jean-Marc Martel  Wilson L. Price 《International Transactions in Operational Research》1994,1(3):363-373

This paper presents a decision support system designed to aid the production planner in choosing the values of the principle parameters governing just-in-time manufacturing. The DSS uses a knowledge base composed of data from simulations of the production of the entire product line under systematically varied conditions. The planners may add data from actual production experience as it is obtained. The stochastic dominance outranking method of Martel and Zaras allows the identification of clusters of parameters that respect the preferences of the decision maker. When launching an order for a product, the decision maker may judge certain sets of parameters to be equivalent. A visual interactive simulation model will then allow their comparison according to three performance criteria.  相似文献   

    

Pauline A Smith  John R Wilson 《Interacting with computers》1993,5(4):371-384

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