Parallel Genetic Algorithms for Optimizing Resource Utilization in Large-Scale Construction Projects

This paper presents the development of a parallel multiobjective genetic algorithm framework to enable an efficient and effective optimization of resource utilization in large-scale construction projects. The framework incorporates a multiobjective optimization module, a global parallel genetic algorithm module, a coarse-grained parallel genetic algorithm module, and a performance evaluation module. The framework is implemented on a cluster of 50 parallel processors and its performance was evaluated using 183 experiments that tested various combinations of construction project sizes, numbers of parallel processors and genetic algorithm setups. The results of these experiments illustrate the new and unique capabilities of the developed parallel genetic algorithm framework in: (1) Enabling an efficient and effective optimization of large-scale construction projects; (2) achieving significant computational time savings by distributing the genetic algorithm computations over a cluster of parallel processors; and (3) requiring a limited and feasible number of parallel processors/computers that can be readily available in construction engineering and management offices.     

Minimizing Construction-Related Hazards in Airport Expansion Projects

Airport expansion projects often require the presence and movement of construction labor and equipment near critical airport traffic areas. This close proximity between construction activities and airport operations needs to be carefully considered during the planning of construction site layouts in order to minimize and eliminate all potential construction-related hazards to aviation safety. This paper presents the development of a multiobjective optimization model for planning airport construction site layouts that is capable of minimizing construction-related hazards and minimizing site layout costs, simultaneously. The model incorporates newly developed optimization functions and metrics that enable: (1) maximizing the control of hazardous construction debris near airport traffic areas; (2) minimizing site layout costs including the travel cost of construction resources and the cost of debris control measures on airport sites; and (3) satisfying all operational safety constraints required by the federal aviation administration as well as other practical site layout constraints. The model is implemented using a multiobjective genetic algorithm and an application example is analyzed to demonstrate the use of the model and its capabilities in optimizing construction site layouts in airport expansion projects.     

Evaluating Cost Overruns of Asphalt Paving Project Using Statistical Process Control Methods

While some projects will experience changes to the contracted cost by deduction or additions, construction cost overruns are becoming a common problem in the construction industry. Steps need to be taken to minimize cost overrun through cost and quality control techniques. This paper presents a study conducted to evaluate construction cost overruns of asphalt paving operations performed by the Illinois Department of Transportation (IDOT). The main objective is to analyze the main causes of cost overruns and evaluate the amount of cost overrun of asphalt paving operations, using statistical process control (SPC) techniques. Real data from projects in the year 2000 were collected from IDOT. These data contain cost information of 219 projects. The results indicate that the average cost overrun for the sample collected was 4% above the bid price. Reasons for cost overruns are analyzed and a Pareto chart and a cause and effect diagram are constructed. Individuals and Moving Range (MR) control charts are developed and their interpretation and use are discussed. Furthermore, the benefits and limitations of using the individuals and MR chart in cost control applications are pointed out. It is recommended that SPC analysis be an integral part in managing and controlling project costs.     

Change Orders Impact on Labor Productivity

This paper describes a study conducted to investigate the impact of change orders on construction productivity and introduces a new neural network model for quantifying this impact. The study is based on a comprehensive literature review and a field investigation of projects constructed in Canada and the USA. The field investigation was carried out over a 6-month period and encompassed 33 actual cases of work packages and contracts. Factors contributing to the adverse effects of change orders on labor productivity are identified and a model presented earlier is expanded to account primarily for the timing of change orders, among other factors. The developed model, as well as four models developed by others, have been incorporated in a prototype software system to estimate the loss of labor productivity due to change orders. A numerical example is presented to demonstrate the use of the developed model, and illustrate its capabilities.     

Bond Strength of Tension Lap Splices in High-Strength Concrete Beams Strengthened with Glass Fiber Reinforced Polymer Wraps

This paper presents the experimental results of the first phase of a study undertaken at the American University of Beirut to examine the effectiveness of fiber reinforced polymer (FRP) wraps to confine steel reinforcement in a tension lap splice region anchored in high-strength reinforced-concrete beams. Seven beam specimens were constructed. The specimens were reinforced on the tension side with three deformed bars spliced at midspan. The splice region was devoid of any transverse reinforcement to allow a full examination of the FRP wrap contribution. Glass fiber reinforced polymer (GFRP) sheets were used. The main test variables were the GFRP configuration in the splice region (one strip, two strips, or a continuous strip), and the number of layers of the GFRP wraps placed around the splice region (one layer or two layers). All GFRP wraps were U-shaped. Except for the epoxy adhesive, no other anchorage mechanism or bonding procedure was applied for the GFRP wraps on the concrete beam. Following the application of the GFRP wraps, the beams were tested in positive bending. The test results demonstrated that GFRP wraps were effective in enhancing the bond strength and ductility of failure mode of the tension lap splices, especially when continuous strips were applied over the splice region.     

Punching Shear Behavior of Flat Slabs Strengthened with Fiber Reinforced Polymer Laminates

The present work reports the test results of seven full-scale reinforced concrete slab-column edge connections strengthened against punching shear using different methods. In this study, three slabs contained openings in the vicinity of the column, and the other four were without openings. The dimensions of the slabs were 1,540×1,020×120 mm with square columns (250×250 mm). The openings in the specimens were square (150×150 mm) with the sides parallel to the sides of the column. The slabs were reinforced with an average reinforcement ratio of 0.75%. Except for the two reference slabs, two different strengthening techniques were considered. Technique I applies externally bonded fiber reinforced polymer (FRP) flexible sheets on the slab around the column in two schemes with one or two layers of FRP sheets glued to the tension face or both tension and compression faces of the slab. Both glass and carbon FRP sheets were considered. Technique II applies externally bonded FRP sheets using either the first or second scheme combined with installing steel bolts through holes across the slab thickness around the column. Based on the test results, it is concluded that the presence of FRP sheets and steel bolts substantially increased the punching capacity of the connections. Code design expressions were conservative in predicting the experimental results.     

Development of serviceability prediction model for county paved roads

This paper developed a pavement serviceability prediction model for county paved roads. Most county paved roads were built decades ago without following minimum design standards. The recent increase in industrial/mineral activities in the State of Wyoming required developing a pavement management system (PMS) for local paved roads. The developed PMS used the pavement serviceability index (PSI) as a pavement performance parameter. The proposed PSI model for local roads is based on: international roughness index, pavement condition index (PCI) and rut depth for flexible pavements only. Ten panellists from Wyoming rated 30 pavement sections that were randomly selected at different distresses’ levels; using two vehicles (SUV and Sedan). The statistical analysis indicated that the seating position, age and gender are not significant to the rating process. However, the vehicle’s type found to be significant. The newly developed model from this study explains 80% of the variations in the PSI values of county roads (adjusted R² = 0.80). In addition, the new model seems to provide more realistic representation of the conditions of county roads than the statewide model used on the state’s highway system.     

Inverse diffraction problems for buried objects in the layered elastic media: the anti-plane problem

The authors study direct and inverse scattering problems for buried objects in the stratified layered elastic media. It is assumed that a source load is applied on the upper boundary surface, to generate a certain wave field inside the medium. Then we build the solutions to the direct problems through specially constructed Green’s functions for every considered case. Using the known measured amplitude of the upper boundary oscillations over a certain finite-length interval, the inverse problems in a one-mode frequency range are solved. Some numerical examples demonstrate the stability of the proposed algorithm for the formulated inverse problems.     

Dual-purpose vardenafil hydrochloride/dapoxetine hydrochloride orodispersible tablets: in vitro formulation/evaluation,stability study and in vivo comparative pharmacokinetic study in healthy human subjects

Erectile dysfunction (ED) is the most important disorder after premature ejaculation for sexual activity in men. Vardenafil hydrochloride (VH) is an oral therapy for the treatment of erectile dysfunction. VH oral disintegrating tablets (ODTs) have been prepared by freeze drying technique to improve its dissolution profile and the overall clinical performance. Dapoxetine hydrochloride (DH) was added to the best three formulae of the prepared VH ODTs to treat premature ejaculation. All the ODTs formulae were evaluated for weight variation, friability, drug content, in vitro disintegration time, wetting time, and the dissolution study. Gelatin as a matrix former with N-methylpyrrolidone as a solubilizer in VH/DH ODTs improved the dissolution rate and extent of release of VH and DH with 100% of drug being dissolved after 15?min. In vivo study results from six healthy male volunteers showed shorter T_max of VH from VH/DH ODT of 0.583?±?0.129?h and shorter T_max of DH from VH/DH ODT of 0.625?±?0.137?h and showed AUC_0–12 of VH from VH/DH ODT of 39.234?±?10.932?ng/ml^?h¹ and AUC_0–12 of DH from VH/DH ODT of 531.681?±?129.544?ng/ml^?h¹, with relative bioavailability values of 100.9 and 85%, respectively, compared to (Levitra^®) and (Priligy^®).     

Clinical pharmacokinetic study for the effect of glimepiride matrix tablets developed by quality by design concept

Objective: Implementation of a new pharmaceutical technique to improve aqueous solubility and thus dissolution, enhancement of drug permeation, and finally formulation of a controlled release tablet loaded with glimepiride (GLMP).

Significance: Improve GLMP bioavailability and pharmacokinetics in type II diabetic patients.

Methods: Different polymers were used to enhance aqueous GLMP solubility of which a saturated polymeric drug solution was prepared and physically adsorbed onto silica. An experimental design was employed to optimize the formulation parameters affecting the preparation of GLMP matrix tablets. A compatibility study was conducted to study components interactions. Scanning electron microscope (SEM) was performed before and after the tablets were placed in the dissolution medium. An in vivo study in human volunteers was performed with the optimized GLMP tablets, which were compared to pure and marketed drug products.

Results: Enhancement of GLMP aqueous solubility, using the polymeric drug solution technique, by more than 6–7 times when compared with the binary system. All the studied formulation factors significantly affected the studied variables. No significant interaction was detected among components. SEM illustrated the surface and inner tablet structure, and confirmed the drug release which was attributed to diffusion mechanism. The volunteer group administered the optimized GLMP tablet exhibited higher drug plasma concentration (147.4?ng/mL), longer time to reach maximum plasma concentration (4?h) and longer t_1/2 (7.236?h) compared to other groups.

Conclusions: Matrix tablet loaded with a physically modified drug form could represent a key solution for drugs with inconsistent dissolution and absorption profiles.