A review of the cost estimation issues in the tender preparation process in construction industry

Cost estimation process is undertaken to predict the total cost of the project. Studies indicate that one of the construction company failures in contracting is because of the uncertain, incorrect, and unrealistic cost estimation. Cost estimation process are heavily influenced by the complexity of the project, scale and scope of construction, market conditions, method of construction, site constraints, client’s financial position, buildability and the location of the project. However, there are other combinations factors that have not been studied thus far. Hence, this paper focuses on the review of other researchers’ findings in relation to cost estimation issues in the construction industry. Among the findings, it has been revealed that the cost estimation issues are related to accuracy, human factors, practical knowledge and insufficient cost data/information. The aim of this paper is to investigate these factors and determining other potential factors that may influence cost estimation process in the construction industry.

Use of ultraviolet C (UVC) radiation to inactivate infectious hematopoietic necrosis virus (IHNV) and viral haemorrhagic septicaemia virus (VHSV) in fish processing plant effluent

We determined the stability of infectious hematopoietic necrosis virus (IHNV) and viral hemorrhagic septicemia virus (VHSV) suspended in either fish processing plant effluent blood water (EBW) or culture media and examined the effectiveness of UVC radiation to inactivate IHNV and VHSV suspended in both solutions. Without exposure to UVC, IHNV and VHSV were maintained in 4°C blood water for up to 48 hours without significant reduction in virus titer. However when exposed to UVC radiation using a low pressure mercury vapour lamp collimated beam, IHNV and VHSV were inactivated, and the efficacy of UVC radiation was dependent upon the solution and virus type being treated. A 3-log reduction for VHSV and IHNV in culture media was achieved at 3.28 and 3.84 mJ cm-2, respectively. The UV dose needed for a 3-log reduction of VHSV in EBW was 3.82 mJ cm-2. However, exposure of IHNV in EBW to the maximum UVC dose tested (4.0 mJ cm-2) only led to a 2.26-log-reduction. Factors such as particle size, and possible association of viruses with suspended EBW particulate, were not investigated in this study, but may have contributed to the difference in UVC effectiveness. Future work should emphasize improved filtration methods prior to UV treatment of processing plant EBW at an industrial scale.

The factors that affect the cost estimation activities in the tender preparation process in the Malaysian construction industry

The possibility of winning the tender is subject to the cost estimation proposed by the contractors compared to the cost estimation prepared by the client’s representative. Studies indicated that one of the construction company failures in the tendering process is due to the uncertain, incorrect, and unrealistic cost estimation. Failure to provide a competitive cost estimation on time is the main reason the contractor is not successful in winning the tender, and will not be considered for the tender evaluation stage. The aim of this paper is to validate the key factors that affect the cost estimation activities in the tender preparation process. This paper describes the results of a pilot study, from a questionnaire survey on the factors that affect the cost estimation activities in the tender preparation process. The study shows the importance of all the factors in the cost estimation activities in the tender preparation process in terms of human factors, working culture, and information technology.

Robust channel estimation algorithm for dual-hop MIMO relay channels

In conventional two-phase channel estimation algorithms for dual-hop multiple-input multiple-output (MIMO) relay systems, the relay-destination channel estimated in the first phase is used for the source-relay channel estimation in the second phase. For these algorithms, the mismatch between the estimated and the true relay-destination channel affects the accuracy of the source-relay channel estimation. In this paper, we investigate the impact of such channel state information (CSI) mismatch on the performance of the two-phase channel estimation algorithm. By explicitly taking into account the CSI mismatch, we develop a robust algorithm to estimate the source-relay channel. Numerical examples demonstrate the improved performance of the proposed algorithm. © 2012 IEEE.

Precocious egg development in the blowfly Calliphora vicina : implications for developmental studies and post-mortem interval estimation

The occurrence of precocious egg development in forensically important calliphorid species has previously been reported; however, the frequency of occurrence in both wild and captive colonies, and the consequent effects on developmental studies and post-m

Wind farm power uncertainty quantification using a mean-variance estimation method

This paper proposes an innovative optimized parametric method for construction of prediction intervals (PIs) for uncertainty quantification. The mean-variance estimation (MVE) method employs two separate neural network (NN) models to estimate the mean and variance of targets. A new training method is developed in this study that adjusts parameters of NN models through minimization of a PI-based cost functions. A simulated annealing method is applied for minimization of the nonlinear non-differentiable cost function. The performance of the proposed method for PI construction is examined using monthly data sets taken from a wind farm in Australia. PIs for the wind farm power generation are constructed with five confidence levels between 50% and 90%. Demonstrated results indicate that valid PIs constructed using the optimized MVE method have a quality much better than the traditional MVE-based PIs.