A Pre-Selection-Based Ant Colony System for Integrated Resources Scheduling Problem at Marine Container Terminal

Marine container terminal(MCT)plays a key role in the marine intelligent transportation system and international logistics system.However,the efficiency of resource scheduling significantly influences the operation performance of MCT.To solve the practical resource scheduling problem(RSP)in MCT efficiently,this paper has contributions to both the problem model and the algorithm design.Firstly,in the problem model,different from most of the existing studies that only consider scheduling part of the resources in MCT,we propose a unified mathematical model for formulating an integrated RSP.The new integrated RSP model allocates and schedules multiple MCT resources simultaneously by taking the total cost minimization as the objective.Secondly,in the algorithm design,a pre-selection-based ant colony system(PACS)approach is proposed based on graphic structure solution representation and a pre-selection strategy.On the one hand,as the RSP can be formulated as the shortest path problem on the directed complete graph,the graphic structure is proposed to represent the solution encoding to consider multiple constraints and multiple factors of the RSP,which effectively avoids the generation of infeasible solutions.On the other hand,the pre-selection strategy aims to reduce the computational burden of PACS and to fast obtain a higher-quality solution.To evaluate the performance of the proposed novel PACS in solving the new integrated RSP model,a set of test cases with different sizes is conducted.Experimental results and comparisons show the effectiveness and efficiency of the PACS algorithm,which can significantly outperform other state-of-the-art algorithms.

Traffic condition estimation with pre-selection space time model

A pre-selection space time model was proposed to estimate the traffic condition at poor-data-detector,especially non-detector locations.The space time model is better to integrate the spatial and temporal information comprehensibly.Firstly,the influencing factors of the "cause nodes" were studied,and then the pre-selection "cause nodes" procedure which utilizes the Pearson correlation coefficient to evaluate the relevancy of the traffic data was introduced.Finally,only the most relevant data were collected to compose the space time model.The experimental results with the actual data demonstrate that the model performs better than other three models.

A Spectrum Prediction-Based Frequency Band Pre-Selection over Deteriorating HF Electromagnetic Environment

As the earliest invented and utilized communication approach, shortwave, known as high frequency(HF) communication now experience the deterioration of HF electromagnetic environment. Finding quality frequency in efficient manner becomes one of the key challenges in HF communication. Spectrum prediction infers the future spectrum status from history spectrum data by exploring the inherent correlations and regularities. The investigation of HF electromagnetic environment data reveals the correlations and predictability of HF frequency band in both time and frequency domain. To solve this problem, we develop a Spectrum Prediction-based Frequency Band Pre-selection(SP-FBP) for HF communications. The pre-selection of HF frequency band mainly incorporated in prediction of HF spectrum occupancy and prediction of HF usable frequency, which provide the frequency band ranking of spectrum occupancy and alternative frequency for spectrum sensing, respectively. Performance evaluation via real-world HF spectrum data shows that SP-FBP significantly improves the efficiency of finding quality frequency in HF communications.

Comparative Study on the Dwarfing Pre-selected Indices of Pear Germplasms with Different Growth Potentials

[ Objective] The aim of this study was to provide a theoretical basis for breeding selection, matching parents and the identification of traits during early period. [ Method ] With Shanli （ Pyrus ussuriensis Maxim） , S2 × Shanli （vigorous）, S2 x ShanU （dwarfing）, S2, super-dwarfing germplasm as the matedais, the dwarfing traits of each germplasm were identified by indices including leaf stomata density, branch-cortex ratio, leaf thickness, palisade tissue thickness, paisade-spongy ratio and vessel density. [Result] Among five kinds of pear germplasms, Shanli with strong growth potential had the smallest branch-cortex ratio, leaf thickness, palisade tissue thickness and palisade-spengy ratio, but the largest stomata density and vessel density. On the contrary, super-dwarfing germplasm with weak growth potential had the largest branch-cortex ratio, leaf thickness, palisade tissue thickness and palisade-spongy ratio, but the smallest stomata density and vessel density. There was a difference in stomata density, branch-cortex ratio, leaf thickness, palisade tissue thickness, palisade-spongy ratio and vessel density for every germplasm. [ Conclusion] Stomata density, branch-cortex ratio, leaf thickness, palisade tissue thickness, palisade-spongy ratio and vessel density can be used as indices of identification for pear growth potential in early period.

Contractor Monitoring and Performance of Road Infrastructure Projects in Uganda: A Management Model

An understanding of the influence of contractor monitoring on performance of road infrastructural projects in Uganda provided an impetus for this study. The objectives of the study were to: assess the relationship between contractors monitoring and performance of national road infrastructure projects and the relationship between contractor monitoring components and performance of national road infrastructure projects in Uganda. Purposive sampling was employed in selecting the procurement professionals, engineers and simple random sampling was adopted in selecting private consultants, members of parliament and respondents from the civil society organizations. Data for this study were collected using a closed ended questionnaire and interviews. Some of the major finding from this study include: weak procurement rules which lead to awarding road projects to incompetent contractors;contractor monitoring being handled by unqualified, incompetent and inexperienced professionals;lack of contractors and contract supervisors appraisal system;delay of contractors payments which affects timelines in services delivery;lack of a strong internal project monitoring and evaluation mechanism at the Uganda National Roads Agency (UNRA). The research therefore recommends the establishment of an Independent Public Infrastructure Development and Monitoring Unit by government and adoption of systems that appraise both contractors and contract supervisors with clear disciplinary actions for unsatisfactory performance by the UNRA.

Synthetic Evaluation of Contractor's Performance in Outcome-Based Contract

Outcome-based contract( OBC) is a kind of contracting mechanism,which allows the customer to pay only when the firm has delivered outcomes,rather than activities and tasks involved. To achieve the higher demand of the delivering outcome of the contract,the evaluation of contractor's performance was focused on. A reasonable and objective contractor performance evaluation system is constructed by considering various uncertainties. The set pair theory is used to analyze the four-element connection of quality of service contractors. It aims to provide a theoretical basis for the decisionmaker to make confirmation of the equipment contractor who has a better performance and development trend.

A NOTE ON PROBABILISTIC CONTRACTOR COUPLE AND SOLUTIONS FOR A SYSTEM OF NONLINEAR EQUATIONS IN N A MENGER PN-SPACES

The concept of (Phi, Delta)-type probabilistic contractor couple was introduced which simplifies and weakens the definition of probabilistic contractor couple given by Zhang Shisheng. The existence and uniqueness of the solutions for a system of nonlinear operator equations with this kind of propabilistic contractor couple in N. A. Menger PN-spaces were studied. The works improve and extend the corresponding results by M. Altman, A. C. Lee, W. J. Padgett et al.

Prediction of Client Support on Contractor Performance as a Critical Success Factor

The aim of this study was to assess the influence of client support on performance of contractors within the road construction industry in Kenya. The study adopted descriptive survey research design and correlation research design. The target population was 156 selected from road contractors, engineers working in road authorities, technical auditors and consultants in the road sector. Stratified and proportionate sampling techniques were employed in coming up with a sample size of 62 respondents drawn from a target population of 156. From the simple linear regression conducted, the findings revealed that client support influences the performance of contractors in the road construction sector. Thus, we recommend that client support is highly needed to avoid issues such as delayed payment that would adversely affect performance of contractors in the road construction industry. This will subsequently lead to timely completion of roads, achieving cost effective and quality road projects.

Investigating Challenges in Financing Contractors for Public Sector Projects in Ghana

Contractors working with the Public sector encounter numerous challenges in financing projects in Ghana. The challenges which have persisted over the years are both financial and managerial. This paper seeks to ascertain the extent to which contractors’ challenges in acquiring funds to execute public sector projects have been solved. The study involved both qualitative and quantitative methods to ascertain the various strategies the contractors go through to obtain public sector projects focusing on the challenges associated with the project execution. The study revealed that delayed payments and inadequate cash flow on the part of government, lack of credit worthiness and inadequate collateral security from contractors are key determinants to challenges associated with financing public sector projects in Ghana. This paper recommends the establishment of a Construction Development Authority (CDA), within the Ministry of Works and Housing to develop financial plans, policies and laws for this important sector of the economy.

（Φ，△）－TYPE PROBABILISTIC CONTRACTOR AND SOLUTIONS FOR A NONLINEAR OPERATOR EQUATIONS IN MENGER PN－SPACES

The purpose of this paper is to introduce the coneept of (Φ,△)-type probabilistic contractor in Menger PN-spaces and to study the existence and uniqueness of solutions for the nonlinear operator equations with such probabilistic contractor in Menger PN-spaces.The results presented in this paper improve and extend the corresponding results in [1] and [4-8].

Contractor Selection Criteria in Ghanaian Construction Industry: Benefits and Challenges

Selecting a contractor for construction project is a difficult decision to be taken by a client because it may lead to construction delivery problems or successful delivery of the project. This study, therefore, investigated the contractor selection criteria in the Ghanaian construction industry, considering the benefits and challenges. A quantitative research method was adopted in this study through the use of a questionnaire. The target population for the study consisted of registered contractors and consultants in the Ashanti and Brong-Ahafo regions of Ghana. It was found that though the construction professionals are well vested with the prequalification selection criteria that are being used within the Ghanaian construction industry, they were not familiar with multi-criterial section methods. It was also found that the benefits of the contractor selection criteria include: enabling the client to select contractors who are performers for the project, saving the project owner a lot of time, minimizing the possibility of contractor default, and facilitating the achievement of project success and the objectives within the scheduled time. Furthermore, excessive cost and time overrun, poor quality standard, imprecise assessments due to lack of information, criteria being very complex and difficult to apply in practice, among others were identified as the challenges to the contractor selection criteria in Ghanaian construction industry. The study recommends for further studies to determine the impact of the identified challenges on construction projects, and ways to minimize the challenges.

Evaluating Contractors’ Safety Record and Its Influence on Performance of Road Infrastructural Projects

A number of studies conducted in Kenya and internationally indicated that most of the construction firms and contractors do not seem to strictly observe safety administration in construction industry, hence compromised performance at implementation stage of projects and even later in the post implementation or post-delivery stage. The study aimed to examine the influence of contractors’ safety record on road performance. This is to create better understanding of how the safety record of contractors could either positively or negatively influence performance of roads during post-delivery stage. The study used both descriptive survey research design and correlation design based on a pragmatic mixed method approach. Through stratified sampling and proportionate sampling, a sample of 210 was drawn from a population of 460 comprising of registered contractors and Public Service Vehicles (PSV) drivers within Nairobi County in Kenya. Questionnaires were distributed using simple random sampling. The questionnaires returned were 153 in total representing 72.8% of all questionnaires distributed to the respondents. Data was descriptively analyzed using percentages, frequencies, means and standard deviations for measuring central tendency and variability. Inferential analysis was done by use of correlation and regression. The descriptive analysis revealed that safety policy management system, insurance policy, and adequacy of standards in addressing safety outcome are to some extent practiced and adhered to. However, compliance behavior to safety procedures is still weak and requires improvement. The null hypothesis was tested and the results obtained from a simple linear regression indicated that, R = 0.657, R2 = 0.431, B = 0.359, t = 10.703, F (1,151) = 114.558, p = 0.000 < 0.05. This means that contractors’ safety record has a strong positive and significant relationship with road performance and that 43.1% of variation in performance is explained by safety record. This study recommends that contractors’ safety record should be part, and parcel of the evaluation criteria used in selection of a suitable road contractor to ensure road performance is achieved even after construction is completed. The study is significant in that it contributes to the body of knowledge by providing empirical data on the need for safety procedures in urban road construction and beyond.

Fuzzy MCDM Model for Selection of Infectious Waste Management Contractors

Healthcare supply chains are under pressure to drive down costs because of digital business,shifting customer needs and new competition.Medical waste generated from medical facilities includes medical activities and daily-life activities of patients and their family members.According to statistics of the Department of Health EnvironmentalManagement,Vietnam currently has more than 13,500 medical facilities,including hospitals from central to provincial and district levels and private hospitals and medical facilities.Preventive medicine generates about 590 tons of medical waste/day and is estimated to be about 800 tons/day.Medical waste includes ordinary medical waste and hazardous medical waste;in which ordinary medical waste accounts for about 80%–90%,only about 10%–20%is hazardous medical waste including infectious waste and non-infectious hazardous waste.This is an environmental and occupational health issue that needs attention in developing countries like Vietnam.Handling large amounts of medical waste to ensure environmental and personal hygiene,doing so inefficiently creates potential hazards to the environment and increases operating costs.However,hospitals lack objective criteria and methods to evaluate and select the most optimal infectious medical waste,relying instead on their own subjective assessment and prior experience.Therefore,the author proposed a fuzzy multicriteria decision making(MCDM)model including Fuzzy Analytic hierarchy process(FAHP)and the Weighted Aggregated Sum-Product Assessment(WASPAS)for infectious medical waste contractors’selection in this research.The proposed Fuzzy MCDM method is in-tended to provide a more efficient,accurate method in the selection of infectious medical waste contractors than subjective assessment methods,thus reduce potential risks to hospitals.The results of this study can be applied to evaluate and select contractors in other industries.

Analysis of top Chinese contractors' developmental tracks and evaluation of their strategic selection of international construction markets

The past decade has witnessed a rapid development of the international construction market. This research aims to investigate top Chinese contractors' developmental tracks and evaluate their strategic selection of international construction markets over the period from 2001 to 2006,based on the modified Boston Consulting Group Matrix (BCG). Results from 2001 to 2005 indicate that Asia and Africa,which were "question marks" markets for top Chinese contractors (abbreviated as TCCs),have the most potential to become "stars" markets; other question marks markets such as the Middle East and Europe are found not to be of potential; "dogs" markets such as the U.S.,Canada and Latin America should be relinquished progressively unless there is renewed growth opportunity over the next two years. Compared to developmental tracks of top contractors from some advanced countries,TCCs' investment and development strategy in Africa seems to be sustainable and intensive; TCCs' exit strategy for the Middle East appears determined and swift,while their strategy in Asia seems to be lacking in persistence. Furthermore,the data of 2006 indicates that TCCs improve their performance in Asia and Africa,and Africa has become a "stars" market for TCCs.This research sheds important lights and insights into the prevailing process of internationalization of TCCs and provides a strategic direction for their selection of international construction market. What is more,this research is also valuable to other Chinese contractors who are seeking the opportunity to enter the international construction markets.

Effects of Delayed Payment of Contractors on the Completion of Infrastructural Projects： A Case of Sondu-Miriu Hydropower Project, Kisumu County, Kenya

Sondu-Miriu hydropower （SMHP） project experienced delay for about five years and one of the contributing factors was delayed payment of the contractor, with ripples effect extending down the contractual hierarchy. This study assessed the effects of delayed payment of the contractor on the completion of SMHP project in Kisumu County, Kenya. More specifically, the study addressed two research questions： What is the relative importance of delayed payment of the contractor compared to other forms of contractual delays？ What is the perceived effect of delayed payment of the contractor on the project＇s completion？ A causal-comparative design was adopted and primary data sourced in May 2011 from 39 senior management staff of contractual parties. Relative importance index （RII） was used to determine the relative importance of perceived effects of delayed payment of the contractor on the project＇s completion; while Kendell＇s coefficient of concordance was applied to determine the degree of agreement among participants regarding their perceived effects of delayed payment. The study found that delayed payment of the contractor affected the project by causing： loss of productivity and efficiency （71.8%）; increase in time-related costs （71.8%）; re-scheduling and re-sequencing of works （69.2%）; extension of time and acceleration （69.2%）; as well as prevention of early completion （53.8%）. The study concludes that timely payment of contractors is crucial for ensuring the continuity of works and completion of infrastructural projects within time, budget, and quality specifications. The study recommends the need for appropriate mitigative measures against potential risks, such as delayed disbursement of funds by external financiers, delayed approval of contractors＇ payment requests, as well as community participation and involvement of civil society to influence accountability in the management of project funds and expedite disbursement of funds for subsequent project phases.

Comparative Study of Information Technology Use by Architects, Engineers and Contractors

The use of information technology （IT） in construction is expanding rapidly. More and more architecture, engineering, and construction companies are adopting new technologies in software design to help accelerate and accurately carry out their functions. Based on a research study carried out in Southern Nevada with a questionnaire survey of 54 construction-related firms, this study aims to compare the types and extent of IT use by architects, engineers, and contractors. It also explores the level of IT skills possessed by professionals working in the industry. The study found that architects mostly used design software whereas engineers and contractors used scheduling and estimating software. All of the respondents believed that IT helped to improve their work productivity. The majority of the respondents thought that IT is useful for Construction Management （CM） students： engineers and architects thought that CM students should take more scheduling and estimating software courses and contractors thought that they should take more scheduling and quantity take-off software courses.

Effects of Internal Control System Deficiency on Contractors＇ Infrastructural Development Capability in the Nigerian Public Sector

Infrastructure development in Nigeria has attracted the attention of researchers in view of the attitudes of contractors and government lead-lag role playing. These attitudes led to the enactment of Fiscal Responsibility Act 2007 and Public Procurement Act 2007 to reduce internal control system deficiencies and budget indiscipline in the Nigerian public sector fiscal matters and procurement process. Ironically, despite these efforts, infrastructure development is still a problem affecting the lives of Nigerians as their poverty level is on the increase. This paper tests the effects of internal control system deficiency on contractors＇ capability in infrastructure development in the Nigerian public sector. Data drawn from a sample of 228 infrastructures were used for analysis. Two research questions on contractors＇ fiduciary obligation to government and capacity were analysed. Kendall＇s Tau-br correlation of coefficient and Chi-square X^2 statistics were employed for data analysis. Findings show that deficient internal control system strongly and directly breeds deficiency in the contractors＇ capability for infrastructure development. The paper recommends that oath of bribery should complement oath of secrecy to ensure that contractors and government agencies that are responsible for execution of infrastructure play to the rules of the ＂games＂, especially the provisions of Public Procurement Act 2007 and Fiscal Responsibility Act 2007. Public-private-partnership-initiative, such as build-operate and transfer method of contracting, should be encouraged to improve on contractors＇ capability and stewardship.

BIM-Enabled Estimating through Technology Ontology for Owners and Contractors

There are progressive architects, engineers, contractors and owners that adopt some of the newest technologies for financial benefits. The moving force to integrate BIM （building information modeling） tools may come from owners demanding a BIM deliverable to approve the work on these projects. Ifa contractor can produce this deliverable, then obtaining the project could be done in a more convincing way. Contractors are confronted with problems in selecting proper construction methods and applying their knowledge about specific and well-defined technologies to a project. Their decision-making process and better project outcomes can be improved through a database-oriented library of construction methods and therefore, a consistent methodology to classify construction methods is needed. This goal can be achieved by introducing rigorous construction method descriptors. The technology solution and the trending need of owners to pay software companies to develop software that really works for them and contractors are empirically proved in this paper through a technology ontology and BIM-enabled estimating procedure. An exploratory case study is presented. This way, owners can efficiently demand deliverables that can be utilized by them downstream, allowing contractors and subcontracting trades to work efficiently and to assure the daily flow of operations.

A trust-based method for selection of contractors in construction industry

This paper presents a method for construction contractor selection based on trust building. By classifying criteria into three types of trust and applying gray correlation analysis, the presented method concerns multi-criteria for evaluation other than price, selects trust- and selection-related criteria, provides approaches for indicator quantification and determines the contractor on the basis of gray correlation degree.

Organizing Independent Contractors in South Korea： A Case of Insurance Solicitors Unionizing

The purpose of this study is to understand limitations and possibilities of organizing independent contractors by focusing on insurance solicitors in South Korea. Among various types of precarious employment, insurance solicitors are an exemplar case of independent contractor jobs in Korea. According to the narrow interpretation on the employment relationship by the courts, the labor standard law does not treat insurance solicitors as workers. And, most of insurance solicitors are not affiliated with labor unions. As a result, insurance solicitors are outside labor protections. Under this context, insurance solicitors attempted to organize their own union--Korean Insurance Agents＇ Union （KIAU） in the early 2000s, and turned it into a branch of Korean Finance and Service Workers＇ Union （KFSWU） in 2004. However, the KIAU lost its membership rapidly since the mid-2000s and has failed to revitalize itself until now. So, in this study, the author focuses on the changes in the employment structure behind the growth of the insurance industry in the private sector and the reason why union organizing of independent contractors was not successful.