Jingyang Zhou

A Review of Methods and Algorithms for Optimizing Construction Scheduling

Optimizing construction project scheduling has received a considerable amount of attention over the past 20 years. As a result, a plethora of methods and algorithms have been developed to address specific scenarios or problems. A review of the methods and algorithms that have been developed to examine the area of construction schedule optimization (CSO) is undertaken. The developed algorithms for solving the CSO problem can be classified into three methods: mathematical, heuristic and metaheuristic. The application of these methods to various scheduling problems is discussed and implications for future research are identified.

Assessing the impact of RFIs in electrical and instrumentation engineering contracts

Using a case study, errors, omissions and information redundancy contained in the electrical and instrumentation (E&I) ‘As-built’ drawings for a Stacker Conveyor were examined. A total of 449 errors and omissions were identified within 42 documents. In addition, 231 cables and components appeared once among the 42 documents; 86 cables and components appeared twice and 12 cables and components appeared thrice. As a result of the errors, omissions and redundancy, requests for information (RFIs) were required. Retrospective analysis indicates that the indirect cost of raising the RFIs to the contractor was estimated to be approximately 9% of the cost of the E&I contract. To address the problems of errors, omissions and redundancy, it is suggested that there is a need to adopt an object orientated system information model (SIM) for E&I engineering design and documentation. It is demonstrated in the case study that the use of a SIM could bring significant improvements in productivity and reduce the cost of engineering design.

Systems information modelling: Enabling digital asset management

Abstract Having access to the right information at the right time has been, and remains a pervasive problem during operations and maintenance (O&M) and thus hinders an asset owners ability to ensure their facilities performance are being optimized. Typically, asset managers are often confronted with ‘As-built’ documentation that is prepared using Computer-Aided-Design (CAD) and is often incomplete, erroneous and/or redundant, which adversely impacts an assets integrity and productivity during O&M. With this mind, the quality of information contained within ‘As-Built’ electrical documentation for an ‘Underground Railway Station’ is evaluated by quantifying the errors and omissions contained within them. The cost to document information using CAD compared to the development of a System Information Model (SIM) is determined. A retrospective SIM is constructed and a bi-directional link with a three dimensional (3D) model is established to ensure the integrity of the information required for O&M. The use of a SIM instead of CAD can provide engineers with a new medium and process for preparing the design and documentation of electrical systems as it provides them with an ability to obtain significant productivity and cost benefits. The empirical research presented in this paper provides the impetus for future research in the fertile and unexplored area of Digital Asset Management for infrastructure projects.

A systems information model for managing electrical, control, and instrumentation assets

Purpose – The purpose of this paper is to present a systems information model (SIM) that is akin to a building information model (BIM) and can be used by asset managers and staff to make more informed and quicker decisions about maintenance. Design/methodology/approach – The problems associated with managing assets are examined alongside recent international efforts to standardize methods of data collection for meeting the objectives of owners. A case study in the domain of electrical, control and instrumentation (ECI) documentation is examined in detail, with particular reference to the amelioration of errors and omissions in “as built” drawings in order to provide the underlying foundation to support effective asset management (AM). Findings – The findings show that object oriented data models such as SIM provide a robust structure for effective and efficient AM and associated leverage of benefits throughout the entire facility lifecycle of a project. In particular object oriented data enables appropria...

Nonlinear optimal feedback control for lunar module soft landing

In this paper, the task of achieving the soft landing of a lunar module such that the fuel consumption and the flight time are minimized is formulated as an optimal control problem. The motion of the lunar module is described in a three dimensional coordinate system. We obtain the form of the optimal closed loop control law, where a feedback gain matrix is involved. It is then shown that this feedback gain matrix satisfies a Riccati-like matrix differential equation. The optimal control problem is first solved as an open loop optimal control problem by using a time scaling transform and the control parameterization method. Then, by virtue of the relationship between the optimal open loop control and the optimal closed loop control along the optimal trajectory, we present a practical method to calculate an approximate optimal feedback gain matrix, without having to solve an optimal control problem involving the complex Riccati-like matrix differential equation coupled with the original system dynamics. Simulation results show that the proposed approach is highly effective.

Synchronization control for a class of underactuated mechanical systems via energy shaping

A synchronization control strategy for a class of underactuated mechanical systems is proposed by using the energy shaping technique, aiming to achieve the required performance of the synchronization motion. A synchronization controller is designed based on the interconnection and damping assignment passivity-based control methodology. It will guarantee that the position tracking errors and the synchronization errors of the underactuated mechanical systems are to converge to zero asymptotically. Experiments on a synchronization control system with two single-inverted pendulums as well as simulations of a synchronization control system consisting of four ball-beam devices are presented to demonstrate the effectiveness of the proposed method.

An exact penalty function method for optimising QAP formulation in facility layout problem

A quadratic assignment problem (QAP), which is a combinatorial optimisation problem, is developed to model the problem of locating facilities with material flows between them. The aim of solving the QAP formulation for a facility layout problem (FLP) is to increase a system’s operating efficiency by reducing material handling costs, which can be measured by interdepartmental distances and flows. The QAP-formulated FLP can be viewed as a discrete optimisation problem, where the quadratic objective function is optimised with respect to discrete decision variables subject to linear equality constraints. The conventional approach for solving this discrete optimisation problem is to use the linearisation of the quadratic objective function whereby additional discrete variables and constraints are introduced. The adoption of the linearisation process can result in a significantly increased number of variables and constraints; solving the resulting problem can therefore be challenging. In this paper, a new approach is introduced to solve this discrete optimisation problem. First, the discrete optimisation problem is transformed into an equivalent nonlinear optimisation problem involving only continuous decision variables by introducing quadratic inequality constraints. The number of variables, however, remains the same as the original problem. Then, an exact penalty function method is applied to convert this transformed continuous optimisation problem into an unconstrained continuous optimisation problem. An improved backtracking search algorithm is then developed to solve the unconstrained optimisation problem. Numerical computation results demonstrate the effectiveness of the proposed new approach.

Toward productivity improvement in electrical engineering documentation

Purpose - – The purpose of this paper is to determine the unproductive time and additional cost to re-engineer a safety control system for a Floating Production Storage Offloading vessel that was originally engineered and documented in computer-aided design (CAD). Design/methodology/approach - – The “As-Built” drawings contained numerous errors and omissions, which resulted in a “requests for information” being raised and productivity rates reduced – these costs and productivity losses are quantified. The use of CAD to originally engineer and document the safety control system was found to be inefficient as a 1: Findings - – The use of a SIM to re-engineer and document the new safety control system resulted in significant productivity benefits being achieved. Consequently, it is proffered that a paradigm shift from a 1: Originality/value - – The paper concludes by suggesting that future research is required to examine how processes and procedures can be re-designed to accommodate the use of a SIM.