Applicability of Heuristic Approach in Planning and Scheduling Project

This paper focuses on the application of heuristic approach in solving scheduling problems of ongoing project. This study is primarily aimed at providing a suitable heuristic for finding an optimum resource level, which ought to be kept over the project execution period, and a sensitivity analysis of which resource type ought to be increased in order to reduce the project completion time towards the ultimate. The use of resource utilization and a “constraining index” in the search for optimal solutions to this problem of meeting delivery date requirements, and optimize utilization of multiple resources in project and minimize other resources. Keywords: Heuristic; resource constraints; constraining index.

Optimum Arrangement of Ponds in a Given Area

Several factors that affect the arrangement of ponds in a given area are presented and the weaknesses of the current pond orientation highlighted. The concept of orthogonality in pond layout is also introduced. It is illustrated that non-orthogonal pond arrangement could result in optimal land use. Efficiency, cost of inter-pond pipe connections and maintenance of orthogonal and non-orthogonal systems were discussed. Land area and cost of inter-pond connections could further be reduced if pond shapes other than rectangular shapes are used

THEORETICAL INVESTIGATION OF STRESSES DISTRIBUTIONS IN HOLLOW SANDCRETE BLOCKS DUE TO VARIATION OF CAVITY SIZES AND NUMBER WEB THICKNESS

The relationship between cavity size and number on one hand and combinations of web thicknesses were investigated theoretically. The least number of cavities was 4 for end-web to centre web ratio of 1:2 at constant shell thickness with the least web thickness equal to 12.5mm. The effects of the number of cavities and web thickness on strength were also investigated. The test thin plate distributes the load on the block and the hollow block is regarded as a two way slab. One of the principal findings is that the variation of maximum stresses with the number of cavity is Gaussian for end-web to centre-web ratio of 1:1 but polynomial for 1:2. In addition, the lowest stress is induced when the end to centre ratio is one. The maximum stress, (21.5N/mm2) occurred at the cavity length (a*) of 125mm for 3 cavities while the end (end centre) web thickness (t) was 25mm respectively. In order words, this combination should be avoided as it will lead to creation of highest stress in the hollow sandcrete blocks. The configuration which will result in least stress (0.5N/mm2) is (a *, N, t) = (50mm, 4mm, 50mm). However, this combination also gave a high maximum stress (6.9N/mm2) in a web, implying that the right choice of configuration should be rather the one that creates the smallest set of maximum stresses in all members. Overall, the best configuration is 2 cavities with web thickness 50mm for an end web to centre web ratio of 1:1 (3.3N/mm2). The corresponding values for 1: 2 ratios are 3 cavities with 50mm shell thickness (4.8N/mm2). The method presented showed meaningful insight could be investigating theoretically. http://dx.doi.org/10.4314/njt.v35i2.

Verification of Machinery Salvage Value Function

Salvage value or resale value is one of the cost components of machinery replacement models. Some replacement models exclude salvage value in the build-up of cost. Yet it is the value that is adversely affected by deterioration. Various mathematical formulas for machinery salvage value have been formulated. The formula for salvage value presented by Lake and Muhlemann is of interest. It is presented in an exponential form. The suitability of this function to our industrial environment has to be justified bearing in mind that some assets have little or no secondhand value. To ensure a balanced investigation, efforts are made to obtain salvage values for motor grader, representing large scale industrial environment and photocopier, representing small and medium scale industrial environment. It is difficult to obtain salvage values because records are hardly kept for such values. However, two sets of salvage values are obtained for each of the machines. One set is for the calibration of the salvage value function by Lake and Muhlemann while the other is for comparison between the measured and predicted salvage values. This paper therefore sets out to investigate and verify the suitability of salvage value function formulated by Lake and Muhlemann to our industrial environment. It is hoped that the investigation will lead to a better understanding of the salvage value function for proper application in our industrial environment

Generation of Machinery Deterioration Rates

The effects of deterioration on the resale value of machinery and indeed on the machinery replacement date are yet to be appreciated. Deterioration rates are usually assumed or at best determined by subjective methods as well as methods that are expensive like the popular machinery failure analysis. Most machinery replacement models do not include resale value in the build-up of cost, yet it is the value (component) that is adversely affected by deterioration. The need arises to find simple methods of obtaining reliable values for deterioration rates. This paper provides one of such methods. The first step is to ensure that the generated random numbers are reliable and should pass the statistical test of randomness. There are many ways of generating random numbers. The methods include the congruential, midsquare, manual and RAND table. The computer combines these methods in generating random numbers that are predictable, reproducible and possess the statistical attributes of randomness. In this study the computer is used to generate random numbers which are simple and statistically reliable. The next step is to find a way of converting these random numbers to obtain values for deterioration. The uniform (rectangular) probability distribution readily comes to mind. It possesses a probability density that has inverse value within a range of values and zero elsewhere. This property is exploited in conjunction with the useful life of the machine to convert the random numbers to obtain values for deterioration. This is simple, reliable and cost saving

Dynamic Programming for Machinery Replacement Models.

Dynamic programming is an optimization technique used in solving problems that exhibit the characteristics of overlapping sub-problems and optimal substructure. Optimal substructure indicates that optimal solutions of sub-problems can lead to the optimal solution of the overall problem. Machinery replacement problems exhibit such properties and therefore can be solved by dynamic programming technique. The technique is simple in application and produces definite solutions to machinery replacement problems. It has this advantage over other optimization techniques like the cumbersome forward/backward algorithm which may produce infinite solutions. This paper demonstrates the use of dynamic programming technique in solving machinery replacement problems of a hypothetical front-end loader and an identified Motor Grader. The choice of hypothetical and measured cost data from the construction industry is deliberate. The focus here is on the versatility of the dynamic programming technique in handling such data from the same industry. It can also be extended to other industries. The result reveals the simplicity and efficiency of dynamic programming technique in solving machinery replacement problems. It also shows the difference between hypothetical and measured data. There is also an indication that the Motor Grader has an appreciable secondhand value. The dynamic programming technique is therefore a good tool for industry managers in making machinery replacement decision

Health Information Brokers in the General Population: An Analysis of the Health Information National Trends Survey 2013-2014

BACKGROUND: Health information exchanged between friends or family members can influence decision making, both for routine health questions and for serious health issues. A health information broker is a person to whom friends and family turn for advice or information on health-related topics. Characteristics and online behaviors of health information brokers have not previously been studied in a national population. OBJECTIVE: The objective of this study was to examine sociodemographic characteristics, health information seeking behaviors, and other online behaviors among health information brokers. METHODS: Data from the Health Information National Trends Survey (2013-2014; n=3142) were used to compare brokers with nonbrokers. Modified Poisson regression was used to examine the relationship between broker status and sociodemographics and online information seeking. RESULTS: Over half (54.8%) of the respondents were consulted by family or friends for advice or information on health topics (ie, they acted as health information brokers). Brokers represented 54.1% of respondents earning \u3c $20,000 yearly and 56.5% of respondents born outside the United States. Women were more likely to be brokers (PR 1.34, 95% CI 1.23-1.47) as were those with education past high school (PR 1.42, CI 1.22-1.65). People aged \u3e /=75 were less likely to be brokers as compared to respondents aged 35-49 (PR 0.81, CI 0.67-0.99). Brokers used the Internet more frequently for a variety of online behaviors such as seeking health information, creating and sharing online content, and downloading health information onto a mobile device; and also reported greater confidence in obtaining health information online. CONCLUSIONS: More than 50% of adults who responded to this national survey, including those with low income and those born abroad, were providing health information or advice to friends and family. These individuals may prove to be effective targets for initiatives supporting patient engagement and disease management, and may also be well-positioned within their respective social networks to propagate health messages

Hydraulic & Design Parameters in Full-Scale Constructed Wetland & Treatment Units: Six Case Studies

The efficiency of pond and constructed wetland (CW) treatment systems, is influenced by the internal hydrodynamics and mixing interactions between water and aquatic vegetation. In order to contribute to current knowledge of how emergent real vegetation affects solute mixing, and on what the shape and size effects are on the mixing characteristics, an understanding and quantification of those physical processes and interactions was evaluated. This paper presents results from tracer tests conducted during 2015-2016 in six full-scale systems in the UK under different flow regimes, operational depths, shapes and sizes, and in-/outlet configurations. The aim is to quantify the hydraulic performance and mixing characteristics of the treatment units, and to investigate the effect of size and shape on the mixing processes. Relative comparison of outlet configuration, inflow conditions, and internal features between the six different treatment units showed variations in residence times of up to a factor of 3. A key outcome of this study, demonstrated that the width is a more important dimension for the efficiency of the unit compared to the depth. Results underlined the importance of investigating hydrodynamics and physics of flow in full-size units to enhance treatment efficiency and predictions of water quality models

Regional inequalities in under-5 mortality in Nigeria: a population-based analysis of individual- and community-level determinants

<p>Abstract</p> <p>Background</p> <p>Regions with geographically diverse ecology and socioeconomic circumstances may have different disease exposures and child health outcomes. This study assessed variations in the risks of death in children under age 5 across regions of Nigeria and determined characteristics at the individual and community levels that explain possible variations among regions.</p> <p>Methods</p> <p>Multilevel Cox proportional hazards analysis was performed using a nationally representative sample of 6,029 children from 2,735 mothers aged 15-49 years and nested within 365 communities from the 2003 Nigeria Demographic and Health Survey. Hazard ratios (HR) with 95% confidence intervals (CI) were used to express measures of association among the characteristics. Variance partition coefficients and Wald statistic were used to express measures of variation.</p> <p>Results</p> <p>Patterns of under-5 mortality cluster within families and communities. The risks of under-5 deaths were significantly higher for children of mothers residing in the South South (Niger Delta) region (HR: 1.30; 95% CI: 1.76-2.20) and children of mothers residing in communities with a low proportion of mothers attending prenatal care by a doctor (HR: 1.36; 95% CI: 1.15-1.86). In addition, the cross-level interaction between mothers' education and community prenatal care by a doctor was associated with a more than 40% higher risk of dying (HR: 1.41; 95% CI: 1.21-1.78).</p> <p>Conclusion</p> <p>The findings suggest the need to differentially focus on community-level interventions aimed at increasing maternal and child health care utilization and improving the socioeconomic position of mothers, especially in disadvantaged regions such as the South South (Niger Delta) region. Further studies on community-levels determinants of under-5 mortality are needed.</p