Narrow Results

Exploration algorithms based on the Boustrophedon path seldom consider the impacts of a robot turning at corners on the exploration time. This paper proposes the Forecast-Island and Bidding A*-Euclidean Selecting Boustrophedon Coordination (FIBA*ESBC) algorithm to calculate the turning time at corners in the overall exploration time and introduces a method to estimate the walking time in the Boustrophedon paths in order to determine the directions for path execution. Typically, in bidding-based exploration tasks, the cost is the Euclidean distance between the current position of the robot and the target point. When there is an obstacle between two points, the cost is set to infinity. Therefore, the selected target point is sometimes not optimal. The FIBA*ESBC algorithm is based on the exploration cost of a combination of the Euclidean distance and A* algorithm walking path, which can effectively solve this problem. Because the bidding is based on a greedy algorithm, the robot has a small unexplored island in the later exploration stage; therefore, full exploration is not possible or requires a long time with several repeated paths. The FIBA*ESBC algorithm prioritizes the exploration and estimation of hidden and existing unexplored islands. It can realize complete exploration and decrease the exploration time. Through simulation experiments conducted using Gazebo and RViz, the feasibility of the FIBA*ESBC algorithm is verified. Moreover, a simulation experiment is conducted in MATLAB for comparison with other algorithms. The analysis of the experimental data shows that the proposed algorithm has a relatively short exploration time.

A reverse auction can be likened to a tendering process where a contract is awarded to the lowest bidder. This is in contrast to a conventional forward auction where the highest bidder wins. In this paper we analyze a minority game version of the reverse auction where an extra condition is imposed that, namely, the bid must be unique. In other words, the bidder with the lowest positive unique integer (LUPI) wins. We examine and compare two extrema, namely, the case when all players are rational and the case when all players make random selections.

When a Make-To-Order (MTO) enterprise receives a bidding invitation from a customer, he does not know the demand is price-sensitive or time-sensitive. In order to increase the possibility of winning this contingent order, the enterprise tenders his bid with two options characterized with price and delivery time. One is for time-sensitive demand, and it ensures that the products will be delivered as soon as possible. The other is for price-sensitive demand, and it ensures that the products will be produced at the lowest cost. The enterprise is comprised of several plants that jointly produce custom products and each plant's decision is made in a distributed way. Hence, the enterprise has to coordinate the production plans of these plants to generate the two options. Since Analytical Target Cascading (ATC) can solve multi-level hierarchical distributed problem and its convergence is proven, it is adopted to coordinate the plants' planning. This paper proposes a unique bidding option generating process in which an extended ATC model is utilized to produce time-sensitive and price-sensitive options by adjusting the coefficient of delivery tardiness. The numerical study in this paper demonstrates (1) the extended ATC model works effectively; (2) ATC with augmented Lagrangian relaxation (AL-ATC) is more effective in producing solutions than ATC with quadratic penalty function (QP-ATC); (3) ATC is an effective coordination tool by comparing the solutions made by ATC and All-In-One (AIO).

What constitutes unacceptable client behaviour in competitive tendering is considered based on theoretical, legislative and moral considerations. A range of malpractices is then identified through the examination of reported abuses. Finally, a case study is presented which illustrates some of these practices and the difficulties faced by those affected in offering resistance. It is suggested that a practical solution may found by requiring clients to make a more direct contribution to tenderers' costs.