钻具稳定器修复工艺可靠性探讨

通过分析研究钻具稳定器的可焊性，针对其性能要求选择合理的摘取合金镶块工艺、合理的焊补堆焊材料和工艺参数，使钻具稳定器的修复取得了较为理想的效果，满足了质量要求。     

屋顶花园荷载问题探析

屋顶花园是屋顶绿化的一种特殊形式,而屋面荷载问题则是发展屋顶花园的首要关键问题。本文主要从活荷载和静荷载两个方面阐述了屋顶花园的荷载来源及分类,分析了各类荷载的特点和标准。减少屋面荷载主要从减少静荷载的种植基质重量、优先绿化植物、景观小品的设置规模数量和位置以及排水设施材料等方面入手。     

晶体管多级放大电路中的负载问题研究

多级放大电路由输入级、中间级和输出级组成。通常要求输入级具有输入阻抗高和噪声低的特性;中间级应有较大的电压放大倍数;输出级应有输出阻抗低和输出功率大的特点。对于复杂电路的负载问题分析比较困难,本文对多级放大电路中负载问题做一些总结。     

Economically significant stock market forecasts

It has been known for some time that a small, but statistically significant portion of the monthly variation in excess returns on the S&P 500-stock index is predictable using ex ante information. This paper presents a model whose out-of-sample forecasts have economic significance. Specifically, a switching rule conditioned on out-of-sample forecasts of stock excess returns, produces investment outcomes that mean-variance dominate the buy-and-hold. The switching strategy yields superior risk-adjusted returns as judged by the composite performance measures of Treynor, Sharpe, and Jensen.     

Initially Testing an Improved Extrapolative Hotel Room Occupancy Rate Forecasting Technique

SUMMARY

The existing time series forecasting models either capture the informationof the last few data in the data series or the entire data series is used for projecting future values. In other words, the time series forecasting models are unable to take advantage of the last trend in the data series, which always have a direct influence on the estimated values. This paper proposes an improved extrapolative time series forecasting technique to compute future hotel occupancy rates. The performance of this new technique was tested with officially published room occupancy rates in Hong Kong. Forecasted room occupancy rates were compared with actual room occupancy rates in several accuracy performance dimensions. Empirical results indicate that the new technique is promising with reasonably good forecasting results.     

煤矿井下救援机器人供电系统开发

文章针对煤矿井下救援机器人长时间续航工作的问题,设计开发了一套供电系统。设计了机器人总体结构,构建了供电系统方案,开发了电量监控系统及其算法,并结合实验结果进行了对比分析,证明了该设计方案的可行性。     

论电力工程全过程监理

目前我国建设监理实质上是施工监理,本文提出了在我国电力工程中实施全过程监理,首先论述了在我国实施全过程监理的作用,并就实施全过程监理中存在的问题及对策进行了探讨分析。     

Modeling Tourism Demand

SUMMARY

Most of the existing studies on tourism demand forecasting apply economic models that use mathematical functions, which require many statistical assumptions and limitations. This paper presents a new approach that applies the rough sets theory to form a forecasting model for tourism demand. The objective of this research is to create patterns which are able to distinguish between the classes of arrivals in terms of volume, based upon differences in the characteristics in each arrival. The information about the arrivals was organized in an Information Table where the number of arrivals corresponds to condition attributes, and the classification was defined by a decision attribute that indicated the forecast categorical value of future arrivals. Utilizing Japanese arrivals data in Hong Kong, empirical results showed the induced decision rules could accurately forecast (86.5%) of the test data.     

Rational vs historical reconstruction – a counter-note on Signorino's note on Blaug

Heckscher's 1919 article originated the Heckscher-Ohlin theory of international trade. In 1987 Carl Uhr pointed out that Heckscher in 1928 made another major contribution to economics in a German-language article on ‘intermittently free goods’, presenting ‘a theory of imperfect competition nine years ahead of that by Joan Robinson and Edward Chamberlin, and a discussion of collective goods not priced by the market’. This paper summarizes the salient ideas of Heckscher's article. It evaluates its merits, originality and significance for the history of economic thought, and how it fits into the ‘revolutionary’ developments of the theory of imperfect competition in the 1930s.     

An assessment of Charter airline benefits for Port Elizabeth and the Eastern Cape

Tourism is becoming a vital component for economic development in South Africa. The income generated by the tourism industry is about 6% of the GDP, which is significant but still falls short of the goal set by the White Paper on Tourism in 2000. In the light of South Africa hosting the 2010 Football World Cup, it is important to identify ways of sustainable tourism development that would continue to increase the benefits to the economy long after the event＇s over. The main objective of the research was to explore an idea for increasing the level of tourist income generated in the Port Elizabeth （Eastern Cape） area. The idea was researched by means of conducting a cost-benefit analysis of two tourist related projects. These projects would introduce Charter airline services between Europe and Port Elizabeth. A second objective was to identify constraints on the project or market failures which would prevent their implementation. The economic theory behind the operation of an airline showed that lease costs and aeroplane operating costs are the two most important factors determine Charter airline＇s profitability. In order to offset these costs, airlines must achieve high passenger load factors. Charter airlines have the advantage over scheduled airlines, in that they will only fly if a minimum level of people has pre-booked seats. Two aeroplanes were chosen for comparison purpose： an Airbus A 340-300 and a Boeing 767-300ER. The private benefits calculated were based on load factors between 80 and 95 percent for ticket prices of USD 667 and USD 773. In addition, to private costs and benefits, social benefits were also estimated in the form of additional secondary revenue generated. With the introduction of net social benefits, both projects become profitable. A 50 percent substitution of revenue generated by the Charter tourists reduces the profits for the both projects drastically. A project based on a Boeing 767-300ER is the most efficient project as it has the highest NPV and BCR values. A reduction in the lease cost of the Airbus 340-300 could make projects based on it more competitive. A few constraints on the establishment of a Charter airline operator based in Port Elizabeth are： the lack of adequate runway for the landing of the long-haul carriers and the need of a larger liberalisation of the aviation policy by eliminating protectionism. The cost benefit analysis undertaken in this research does not take into account social costs and benefits to the economy of establishing a Charter airline based in Port Elizabeth, such as an employment, infrastructure development and poverty alleviation. Nevertheless the analysis does suggest that there are strong private and social benefits warranting the establishment of an airline business between Europe and Port Elizabeth. The economic benefits of the tourism industry and its link to airline travel are outlined in section 3. It is shown that the growth of the airline industry is a major component and contributor to tourism growth.