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51.
We will have to wait to see how good our present forecasting methodologies are, but we can test futurologists of earlier times. The author has checked a selection of Fortune's forecasts as far back as 1933. Examination reveals that predictions were on target in three areas-technology, general trends, and structural change in the economy. They fell far short of the mark, however, in the areas of legal, political, and international constraints; the personal impact of economic factors; and the personal impact of various innovations. But the failures were often not too far off and the correct ones, if heeded, could have saved us time and money. Unfortunately, the people problems that plagued the Fortune forecasts are still unsolved today.  相似文献   
52.
We model the dynamics of ask and bid curves in a limit order book market using a dynamic semiparametric factor model. The shape of the curves is captured by a factor structure which is estimated nonparametrically. Corresponding factor loadings are modelled jointly with best bid and best ask quotes using a vector error correction specification. Applying the framework to four stocks traded at the Australian Stock Exchange (ASX) in 2002, we show that the suggested model captures the spatial and temporal dependencies of the limit order book. We find spill-over effects between both sides of the market and provide evidence for short-term quote predictability. Relating the shape of the curves to variables reflecting the current state of the market, we show that the recent liquidity demand has the strongest impact. In an extensive forecasting analysis we show that the model is successful in forecasting the liquidity supply over various time horizons during a trading day. Moreover, it is shown that the model's forecasting power can be used to improve optimal order execution strategies.  相似文献   
53.
With the implementation of the North American Free Trade Agreement (NAFTA) nearly complete, there are concerns that the easy gains in efficiency have been achieved and that additional steps towards the economic integration of the member countries are required. This poses a distinct challenge to the NAFTA governments, since the agreement did not create trinational institutions with the supranational authority to facilitate the deepening of the new trading environment. In any initiative to further the economic integration of the NAFTA countries, agriculture will be a difficult sector in which to make progress. However, at an aggregate level, the support provided directly to agricultural producers by the NAFTA governments is similar, as are tariffs at an aggregate level. All three countries have devised income support programmes that contain a countercyclical element. In each of these areas, as well as in the operation of ‘green box’ programmes that are consistent with the member countries’ obligations to the World Trade Organization, cooperation and consultation among the NAFTA members would seem crucial if they are to achieve greater integration in the agrifood sector. This article examines the opportunities and challenges facing the NAFTA members as they seek further integration in the agrifood sector.  相似文献   
54.
A survey on pickup and delivery problems   总被引:1,自引:0,他引:1  
This paper is the first part of a comprehensive survey on pickup and delivery problems. Basically, two problem classes can be distinguished. The first class, discussed in this paper, deals with the transportation of goods from the depot to linehaul customers and from backhaul customers to the depot. This class is denoted as Vehicle Routing Problems with Backhauls (VRPB). Four subtypes can be considered, namely the Vehicle Routing Problem with Clustered Backhauls (VRPCB – all linehauls before backhauls), the Vehicle Routing Problem with Mixed linehauls and Backhauls (VRPMB – any sequence of linehauls and backhauls permitted), the Vehicle Routing Problem with Divisible Delivery and Pickup (VRPDDP – customers demanding delivery and pickup service can be visited twice), and the Vehicle Routing Problem with Simultaneous Delivery and Pickup (VRPSDP – customers demanding both services have to be visited exactly once). The second class, dealt with in the second part of this survey, refers to all those problems where goods are transported between pickup and delivery locations. These are the Pickup and Delivery Vehicle Routing Problem (PDVRP – unpaired pickup and delivery points), the classical Pickup and Delivery Problem (PDP – paired pickup and delivery points), and the Dial-A-Ride Problem (DARP – passenger transportation between paired pickup and delivery points and user inconvenience taken into consideration). Single as well as multi vehicle versions of the mathematical problem formulations are given for all four VRPB types, the corresponding exact, heuristic, and metaheuristic solution methods are discussed.   相似文献   
55.
Abstract . For more than a generation, contemporary mainland Chinese have lived under first a military dictatorship and now a political party dictatorship. How to explain to an eager Chinese academic audience what the American dream of ‘liberty and justice for all’—realized only in part in some areas but approached progressively nearer in others—really means? The U.S. has predominantly a capitalist system but its people are committed to equality of opportunity. It tempers ‘rugged individualism’ by concern for the poor, the handicapped and the unfortunate. It has many serious economic, social and cultural problems but its citizens, drawn from most of the peoples of the world—not the special interest groups trying to benefit at the expense of others—are determined to solve them equitably and rationally. The trade and budget deficits are related to government instrumentalities.  相似文献   
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Rain is the basic ingredient for the existence of Africa and its people. This article introduces the ‘baseline’ rainfall climatology of Africa and looks at examples of fluctuations in the last 50 years. The author then puts forward some suggestions on the implications of such variability for planning and policy making.  相似文献   
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