Ergonomics of the Operative Field in Paediatric Minimal Access Surgery

Imperial Users onl

A floor sensor system for gait recognition

This paper describes the development of a prototype floor sensor as a gait recognition system. This could eventually find deployment as a standalone system (eg. a burglar alarm system) or as part of a multimodal biometric system. The new sensor consists of 1536 individual sensors arranged in a 3 m by 0.5 m rectangular strip with an individual sensor area of 3 cm2. The sensor floor operates at a sample rate of 22 Hz. The sensor itself uses a simple design inspired by computer keyboards and is made from low cost, off the shelf materials. Application of the sensor floor to a small database of 15 individuals was performed. Three features were extracted : stride length, stride cadence, and time on toe to time on heel ratio. Two of these measures have been used in video based gait recognition while the third is new to this analysis. These features proved sufficient to achieve an 80 % recognition rate

Manufacturers'responses to infrastructure deficiencies in Nigeria : private alternatives and policy options

As cities in developing countries grow, the need to meet increasing demand for urban infrastructure services has become an important policy problem. Failure to respond adequately affects productivity and the quality of life in those cities. In order to make the Bank's lending programs in this area more effective, greater understanding is needed of: (a) the ways inadequate services affect business and productivity in urban areas; (b) the options for more efficiently providing and maintaining the delivery of various infrastructure services; and (c) potential cost savings from improved services. Based on empirical observations, this report suggests policy options for improving the provision of infrastructure services in Nigeria, the first country for which the Bank has undertaken this type of research: (a) regulatory changes to enable greater use of existing private capacity (for example, allowing the sale of excess private electrical power); (b) participation of the private sector in the supply of infrastructure-related services; and (c) pricing policies that are more efficient in the presence of congestion, system failures, and variations in the private provision of services.Banks&Banking Reform,Private Participation in Infrastructure,Microfinance,Economic Theory&Research,Public Sector Economics&Finance

The Forecasting Ability of Money Market Fund Managers and its Economic Value

The model proposed by Merton(1981) to determine the value of forecasting ability is adapted to investigate whether money market fund managers successfully anticipate changes in the yield curve by adjusting the average maturity of their portfolios in the right direction. The potential economic value of such behavior is assessed, and it is shown that if the portfolios of all money market funds were aggregated it would appear that managers are good forecasters even if individually they possess insignifcant forecasting ability. At the same time, the economic value of the aggregate portfolio will be diminished because of the reduced net change in average maturity. Thus, diversifying into many money market funds will not attain the gain that could be realized if an individual manager had a forecasting ability equal to the quality of the average forecast.A sample of 34 money market funds is investigated. Analysis suggests that a small fraction of the funds exhibited forecasting skills, but even they generated negligible economic value because the changes in their portfolios average maturity were too small.There appears to be no relationship between forecasting ability and economic success of money market funds as measured by asset size and growth.

The benefits of alternative power tariffs for Nigeria and Indonesia

The authors present simulation results on the benefits of alternative power tariffs for Nigeria and Indonesia, based on several closely related models of the firm. Nigeria is representative of developing countries where the public sector is inefficient and manufacturers provide their own electricity to compensate for that inefficiency. The use of private generators by Nigerian manufacturers is virtually ubiquitous, even though the government, to protect its monopoly, did not encourage that use in the 1980s. About 89 percent of a sample of Nigerian firms produced some of their power needs internally. But many large firms underused their power plants because of the substantial quantity discounts public power offered to large manufacturers. By contrast, in Indonesia, manufacturers were offered only slight quantity discounts for public power. Indonesia has encouraged manufacturers to produce their own power. About 61 percent of Indonesian manufacturers produced some power internally. Generally, in both countries firms purchase some power from the public sector at a quantitydiscount (slight in Indonesia, considerable in Nigeria) and also produce power internally at a declining marginal cost. The reliability of public power declines as the total quantity purchased increases, because transmission gets congested. Simulations confirm that an increasing block tariff is optimal in each country and produces savings in the cost of producing public power and in firms'operating costs (including the firm's cost of producing power internally). Under increasing block tariffs, firms that purchase more public power would be charged higher marginal prices than firms that purchase less. Large firms respond to the increasing block tariff by expanding their generating capacity and reducing their reliance on public power, while smaller firms contract their capacities and buy more from the public sector. When congestion in transmission persists, cost savings are higher as the increasing block tariff reduces total use of public power which in turn improves reliability. In Nigeria, where strong quantity discounts are offered, total costs savings (for NEPA and manufacturers) under 1989 conditions are about 4 percent without congestion and increase to 9 percent when there is some congestion. In Indonesia, where quantity discounts are mild, increasing the block tariff produces only slight cost savings.Anthropology,Economic Theory&Research,Environmental Economics&Policies,Energy Technology&Transmission,Windpower,Environmental Economics&Policies,Economic Theory&Research,Energy Technology&Transmission,Power&Energy Conversion,Windpower

Intelligent computational sketching support for conceptual design

Sketches, with their flexibility and suggestiveness, are in many ways ideal for expressing emerging design concepts. This can be seen from the fact that the process of representing early designs by free-hand drawings was used as far back as in the early 15th century [1]. On the other hand, CAD systems have become widely accepted as an essential design tool in recent years, not least because they provide a base on which design analysis can be carried out. Efficient transfer of sketches into a CAD representation, therefore, is a powerful addition to the designers' armoury.It has been pointed out by many that a pen-on-paper system is the best tool for sketching. One of the crucial requirements of a computer aided sketching system is its ability to recognise and interpret the elements of sketches. 'Sketch recognition', as it has come to be known, has been widely studied by people working in such fields: as artificial intelligence to human-computer interaction and robotic vision. Despite the continuing efforts to solve the problem of appropriate conceptual design modelling, it is difficult to achieve completely accurate recognition of sketches because usually sketches implicate vague information, and the idiosyncratic expression and understanding differ from each designer

Shape matching and clustering

Generalising knowledge and matching patterns is a basic human trait in re-using past experiences. We often cluster (group) knowledge of similar attributes as a process of learning and or aid to manage the complexity and re-use of experiential knowledge [1, 2]. In conceptual design, an ill-defined shape may be recognised as more than one type. Resulting in shapes possibly being classified differently when different criteria are applied. This paper outlines the work being carried out to develop a new technique for shape clustering. It highlights the current methods for analysing shapes found in computer aided sketching systems, before a method is proposed that addresses shape clustering and pattern matching. Clustering for vague geometric models and multiple viewpoint support are explored