A theoretical analysis of the current-voltage characteristics of solar cells

Various mechanisms which limit the conversion efficiency of silicon solar cells were studied. The effects of changes in solar cell geometry such as layer thickness on performance were examined. The effects of various antireflecting layers were also examined. It was found that any single film antireflecting layer results in a significant surface loss of photons. The use of surface texturing techniques or low loss antireflecting layers can enhance by several percentage points the conversion efficiency of silicon cells. The basic differences between n(+)-p-p(+) and p(+)-n-n(+) cells are treated. A significant part of the study was devoted to the importance of surface region lifetime and heavy doping effects on efficiency. Heavy doping bandgap reduction effects are enhanced by low surface layer lifetimes, and conversely, the reduction in solar cell efficiency due to low surface layer lifetime is further enhanced by heavy doping effects. A series of computer studies is reported which seeks to determine the best cell structure and doping levels for maximum efficiency

A theoretical analysis of the current-voltage characteristics of solar cells

The current-voltage characteristics and efficiencies of solar cells are discussed. For one solar cell structure detailed curves are presented which include carrier densities, current densities, potential, and quasi-Fermi levels at different voltage levels both with and without optically generated carriers (AMO conditions). In addition some results are presented concerning the influence of various parameter variations such as lifetime, cell thickness, and high-low junction width on solar cell performance

The Sea Waters surrounding the Québec-Labrador peninsula

L'histoire de l'exploration des eaux côtières de la péninsule Québec-Labrador remonte très loin dans le temps, mais c'est vraiment l'Année polaire internationale de 1882 qui marqua les débuts des premières recherches sérieuses. Les progrès les plus considérables des recherches océanographiques ont cependant été réalisés depuis la IIe guerre mondiale, grâce surtout aux travaux entrepris dans l'Arctique oriental par le Bureau des recherches sur les pêcheries.L'auteur s'étend d'abord sur l'océanographie physique de la région ; il étudie successivement la bathymétrie, la répartition et les caractères des principales masses d'eau, les courants, les glaces et les marées. Suit une analyse de la biologie marine, qui souligne en particulier l'importance d'un facteur : l'absence de brassage vertical des eaux. La répartition de la faune marine indique que si les régions dominées par les eaux arctiques sont riches en mammifères, celles où l'influence atlantique est forte sont de beaucoup les plus poissonneuses. L'auteur insiste sur l'importance des ressources biologiques de la mer dans l'économie alimentaire des Esquimaux.De même qu'il existe des preuves d'oscillations climatiques à courte période, on peut aussi conclure à un réchauffement des eaux depuis le début du siècle, bien que cette tendance soit moins évidente depuis quelques années

The life cycle of Sagitta elegans in Arctic and Subarctic Seas, and the modifying effects of hydrographic differences in the environment

Sagitta elegans arctica of the Canadian eastern Arctic waters has a life span of two years. Its breeding cycle is two-phase, or alternating, and the population consists of two distinct groups breeding in different years. The spawning period is long, extending from July into the winter, probably up to February. Winter spawning is taken to imply that the breeding behaviour is not timed to coincide with the maximum abundance of food, but that the cycle is determined by the growth limitations imposed by the low temperature...

Gossip on Weighted Networks

We investigate how suitable a weighted network is for gossip spreading. The proposed model is based on the gossip spreading model introduced by Lind et.al. on unweighted networks. Weight represents "friendship." Potential spreader prefers not to spread if the victim of gossip is a "close friend". Gossip spreading is related to the triangles and cascades of triangles. It gives more insight about the structure of a network. We analyze gossip spreading on real weighted networks of human interactions. 6 co-occurrence and 7 social pattern networks are investigated. Gossip propagation is found to be a good parameter to distinguish co-occurrence and social pattern networks. As a comparison some miscellaneous networks and computer generated networks based on ER, BA, WS models are also investigated. They are found to be quite different than the human interaction networks.Comment: 8 pages, 4 figures, 1 tabl

Defining environmental river flow requirements ? a review

International audienceAround the world, there is an increasing desire, supported by national and regional policies and legislation, to conserve or restore the ecological health and functioning of rivers and their associated wetlands for human use and biodiversity. To achieve this, many organisations have developed methods for defining "environmental flows?, i.e. the flow regime required in a river to achieve desired ecological objectives. This paper reviews the various methods available and suggests a simple categorisation of the methods into four types: look-up tables, desk-top analysis; functional analysis and hydraulic habitat modelling. No method is necessarily better than another; each may be suitable for different applications. Whilst look-up methods are easy and cheap to apply, they can be expensive to develop, are less accurate and more suitable for scoping studies; in contrast, although hydraulic habitat modelling is more expensive to apply, it is suitable for impact assessment at specific sites. Each method would need to be used within a wider decision-support framework. These are generally either objective-based to define a target flow regime for a specific desired river status, or scenario-based to indicate the relative merits of various flow regime options for the river environment. Keywords: environmental flow, instream flow, river habitat modelling, building block method, flow scenario analysis, objective setting

Checks and cheques : implementing a population health and recall system to improve coverage of patients with diabetes in a rural general practice

Identification of all diabetic patients in the population is essential if diabetic care is to be effective in achieving the targets of the St Vincent Declaration.1 The challenge therefore is to establish population based monitoring and control systems by means of state of the art technology in order to achieve quality assurance in the provision of care for patients with diabetes. 2,3 Disease management receives extensive international support as the most appropriate approach to organising and delivering healthcare for chronic conditions like diabetes.4 This approach is achieved through a combination of guidelines for practice, patient education, consultations and follow up using a planned team approach and a strong focus on continuous quality improvement using information technology. 5,6 The current software (Medical Director) could not easily meet these requirements which led us to adopt a trial of Ferret. In designing this project we used change management7 and the plan, do, study, act cycle8 illustrated in Diagram 1.<br /

Scaffold searching: automated identification of similar ring systems for the design of combinatorial libraries

Rigid ring systems can be used to position receptor-binding functional groups in 3D space and they thus play an increasingly important role in the design of combinatorial libraries. This paper discusses the use of shape-similarity methods to identify ring systems that are structurally similar to, and aligned with, a user-defined target ring system. These systems can be used as alternative scaffolds for the construction of a combinatorial library

On the hydrographic mechanism of the so-called brown zones associated with tidal glaciers

The presence of zones of muddy, ice-free water at the sea faces of tidal glaciers has been recorded from Alaska (Gilbert, 1910), and from Spitzbergen (Stott, 1936). In view of their great significance in local ecology an understanding of the causes of these so-called Brown Zones seemed desirable and the problem of their establishment was first attacked hydrographically by the Oxford University Expedition to Spitzbergen, in 1933...