6 resultados para Trade off
em WestminsterResearch - UK
Resumo:
Air traffic controller shortages remain a significant challenge in European ATM. Comparing different rules, we quantify the cost effectiveness of adding controller hours to Area Control Centre regulations to avert the delay cost impact on airlines. Typically, adding controller hours results in a net benefit. Distributions of delay duration and aircraft weight play an important role in determining the total cost of a regulation. Errors are likely to be incurred when analysing performance based on average delay values, particularly at the disaggregate level.
Resumo:
This paper deals with and details the design of a power-aware adaptive digital image rejection receiver based on blind-source-separation that alleviates the RF analog front-end impairments. Power-aware system design at the RTL level without having to redesign arithmetic circuits is used to reduce the power consumption in nomadic devices. Power-aware multipliers with configurable precision are used to trade-off the image-rejection-ratio (IRR) performance with power consumption. Results of the simulation case studies demonstrate that the IRR performance of the power-aware system is comparable to that of the normal implementation albeit degraded slightly, but well within the acceptable limits.
Resumo:
Following the 1978 rural reform, a series of agricultural reforms were introduced in China with an aim to create incentives for the farmers to produce more. However, the nineties’ reforms towards liberalization eventually resulted in a huge drop in agricultural production, which apparently motivated the grain self-sufficiency program in 1998. For a dataset that covers wheat production during these reforms, we examine how and to what extent these reforms affected the Total Factor Productivity (TFP) and the welfare of wheat farmers in China, both at the national and at the regional level. We find that although the nineties' price reforms led to a relatively faster growth of the incentivized TFP of wheat production, they failed to improve profits vis a vis welfare for the farmers. A series of weather shocks in the early nineties resulted in a scarcity of cultivable land and a shortage of agricultural labour, which eventually led to a sharp increase in their relative prices. The introduction of grain self-sufficiency program stabilized these agricultural prices but destroyed the growth in TFP for most regions. However, this reform resulted in some improvement in farmers’ welfare. Wheat farmers in China therefore experienced a trade off between productivity and welfare; competition boosted their productivity and regulation improved their welfare. Not only these findings add a completely new set of results to the existing literature, they can also form a strong basis for future agricultural reforms in China.
Resumo:
Waterways have many more ties with society than as a medium for the transportation of goods alone. Waterway systems offer society many kinds of socio-economic value. Waterway authorities responsible for management and (re)development need to optimize the public benefits for the investments made. However, due to the many trade-offs in the system these agencies have multiple options for achieving this goal. Because they can invest resources in a great many different ways, they need a way to calculate the efficiency of the decisions they make. Transaction cost theory, and the analysis that goes with it, has emerged as an important means of justifying efficiency decisions in the economic arena. To improve our understanding of the value-creating and coordination problems for waterway authorities, such a framework is applied to this sector. This paper describes the findings for two cases, which reflect two common multi trade-off situations for waterway (re)development. Our first case study focuses on the Miami River, an urban revitalized waterway. The second case describes the Inner Harbour Navigation Canal in New Orleans, a canal and lock in an industrialized zone, in need of an upgrade to keep pace with market developments. The transaction cost framework appears to be useful in exposing a wide variety of value-creating opportunities and the resistances that come with it. These insights can offer infrastructure managers guidance on how to seize these opportunities.
Resumo:
Ground delay programs typically involve the delaying of aircraft that are departing from origin airports within some set distance of a capacity constrained destination airport. Long haul flights are not delayed in this way. A trade-off exists when fixing the distance parameter: increasing the ‘scope’ distributes delay among more aircraft and may reduce airborne holding delay but could also result in unnecessary delay in the (frequently observed) case of early program cancellation. In order to overcome part of this drawback, a fuel based cruise speed reduction strategy aimed at realizing airborne delay, was suggested by the authors in previous publications. By flying slower, at a specific speed, aircraft that are airborne can recover part of their initially assigned delay without incurring extra fuel consumption if the ground delay program is canceled before planned. In this paper, the effect of the scope of the program is assessed when applying this strategy. A case study is presented by analyzing all the ground delay programs that took place at San Francisco, Newark Liberty and Chicago O’Hare International airports during one year. Results show that by the introduction of this technique it is possible to define larger scopes, partially reducing the amount of unrecovered delay.
Resumo:
Different charging zones are found within European airspace. This allows airlines to select different routes between origin and destination that have different lengths and en-route charges. There is a trade- off between the shortest available route and other routes that might have different charges. This paper analyses the routes submitted by airlines to be operated on a given day and compares the associated costs of operating those routes with the shortest available at the time, in terms of en-route charges and fuel consumption. The flights are characterised by different variables with the idea of identifying a behaviour or pattern based on the airline or flight characteristics. Results show that in some areas of the European airspace there might be an incentive to select a longer route, leading to both a lower charge and a lower total cost. However, more variables need to be considered and other techniques used, such as factor analysis, to be able to identify the behaviour within an airline category.