S.Y. Wang

A method used for evaluating bids in the chinese construction industry

Abstract Firstly, the history of development of competitive bidding systems in China is reviewed. Then, a method for evaluating bids used in Beijing—which is based on multiple criteria such as “Degree of response to the bid document”, “Construction organization design”, “Firm honor and competence”, “Bid prices and amounts used of steel, cement and lumber”, etc—is presented. Thirdly, a real case in the Beijing construction market is given to demonstrate the method. Finally, some problems on the bidding systems presently existing in China that are in urgent need of further research are proposed. This paper will benefit anyone wishing to deal with bidding for a project from China.

A sequential method for preventive maintenance and replacement of a repairable single-unit system

This paper is concerned with when to implement preventive maintenance (PM) and replacement for a repairable ‘single-unit’ system in use. Under the main assumption that a ‘single-unit’ system gradually deteriorates with time, a sequential method is proposed to determine an optimal PM and replacement strategy for the system based on minimising expected loss rate. According to this method, PM epochs are determined one after the other, and consequently we can make use of all previous information on the operation process of the system. Also the replacement epoch depends on the effective age of the system. A numerical example shows that the sequential method can be used to solve the PM and replacement problem of a ‘single-unit’ system efficiently. Some properties of the loss functions W(L̄n,b̄n) and W̄r(N) with respect to PM and replacement respectively are discussed in the appendix.

Booking models for hotel revenue management considering multiple-day stays

This study presents several revenue optimisation models for hotel room reservations for a future target day with multiple-day stays. Assume that the hotel has only one type of room but the unit rate for the room may be different during every booking period and every reservation may cover several days. A stochastic programming model with semi-absolute deviations for measuring the risk for hotel revenue under an uncertain environment is proposed. And this stochastic model can be changed into a linear programming model by applying linearisation techniques. Numerical examples are presented to illustrate the efficiency of these models.

A general multivariate analysis approach for determining bid mark‐up strategy

In choosing a bidding strategy, the original multivariate approach cannot handle a more general and usual bidding situation when the mean value of the bid price for the strategic bidder is not zero. This problem is solved by extending the original approach, assuming that the cost estimate is normally distributed with a non‐zero mean value. The new obtained formula for the probability of winning and the expected profit for the generalized approach are proved to be not influenced by the contract datum parameters and are suitable for determining the optimal mark‐up strategy for a future construction contract. A supplementary model is proposed and combined with the original model to determine relevant parameters in the bid distribution and to justify the previously originally obtained estimation formula. Finally, the real data in the original approach is used to demonstrate the new multivariate analysis approach.

New Generalized Invexity for Duality in Multiobjective Programming Problems Involving N-Set Functions

In this paper, we introduce four types of generalized convexity for an n -set function and discuss optimality and duality for a multiobjective programming problem involving n -set functions. Under some mild assumption on the new generalized convexity, we present a few optimality conditions for an efficient solution and a weakly efficient solution to the problem. Also we prove a weak duality theorem and a strong duality theorem for the problem and its Mond-Weir and general Mond-Weir dual problems respectively.

Optimality and duality for V-invex non-smooth multiobjective programming problems

We consider non-smooth multiobjective programming problems with inequality and equality constraints involving locally Lipschitz functions. Several optimality conditions under various (generalized) V-invexity assumptions and certain regularity conditions are presented. Further, we introduce a Mond–Weir type dual and establish duality relations under the aforesaid assumptions.

Recycling systems design using reservation incentive data

We consider a problem of siting compact scale biomass recycling units in residential districts, where residents can be motivated to participate in the recycling program when offered with sufficient monetary incentives. Available data samples of the residents’ reservation incentive levels are used directly to estimate the recycling participation rate in the model, which is solved for the optimal recycling unit locations and incentive-to-offer. We propose a novel approximation of the participation rate estimator that can significantly improve the tractability and scalability of the resulting mixed integer optimization model. Furthermore, we consider the effects of feedstock impurity on the economic feasibility of the recycling system, and extend our model to develop solutions that can achieve specified profit targets as well as possible in the presence of feedstock impurity. Finally, computational studies show the efficiency of the proposed model and solution approach, and give positive demonstrations of our proposed model in providing the requisite decision support in realistic recycling systems design problems.