Articles in This Issue
Abstract
WMAN (wireless metropolitan area network) technology is based on the IEEE 802.16 air interface standard suite, which provides the wireless technology for fixed and nomadic data access. WMAN employs orthogonal frequency division multiplexing (OFDM), and supports adaptive modulation and coding depending on the channel conditions. The objective of this paper is to study the performance of the IEEE 802.16d WMAN physical layer under Nakagami model as a Multi-path and frequency-selective fading channel beside the additive white Gaussian noise (AWGN) and Doppler. Finally, we compared it with the Rayleigh fading model. The transmission bit rate, Probability of Error ( ) and estimated SNR have been compared under single/multi path propagation conditions.
Abstract
The study of springs Abu-Aljeer natural asphalt at proven of al-anbar (Iraq), to find a mean of exploiting the asphalt springs as alternative energy resource, Included two stages The first: Separation the components of asphalt in two ways the first is column chromatography and second represented by extraction- chromatography. The results of separation were 10.20% Asphltene, 89.18% Maltene which separated lately to (Paraffinic 45.23%, Aromatic 28. 39% and Resin 21.66%). The second: Trying to improve the asphalt specifications by using natural materials that are available locally (limestone) with (5, 15, 25, 35%), which have given good results. Rheological properties have been tested, in such average that (virgin Softening was 430C, became 560C, Penetration was 110 dropped 39 and viscosity was 11355 turnedy other 47231cent-Stok, mm2Sec), and flash point ( 1790 C became 200 0C), Fractionated parts of asphalt were characterized by (UV), (FT-IR) spectra. This study also clarified paraffin compounds which represent the main part material and the colloidal state is in Gel phase.
Abstract
Estimation of the reliability for repairable system after maintenance actions is usually based on mathematical models, which can be classified as parametric and non-parametric models where the parametric model is required a prior specified life time distribution while Non-parametric model is that relaxes of the assumption of the life time distribution. Nonparametric life time models are including proportional hazard model and proportional odd model. In this paper we develop repairable reliability model concentrate on generalized repairable model that indicate the mixture of proportional hazard model and proportional odd model. A proportional hazard-proportional odds (PH-PO) model for the purpose of to improve the repairable reliability to obtain accurate estimates of reliability for repairable industrial boiler system at normal operating conditions depending on transformation parameter for reliability prediction for repairable system that represent Beji industrial boiler in power plant. The results show the odd model better than hazard model for repairable system after preventive maintenance depends on time to repair where transformation parameter (c) equal 0.0525094 it is closer to odds model than hazard model. In addition, reliability industrial boiler in case without temperature effect is better than reliability with temperature effect by using exponential model where we note that the reliability at 500 it is worse state where degrade more than (400,450) .
Abstract
The white cement Kiln dust (WCKD) is a secondary production from the cement industry through its production operation. Environmentally, it is considered as an unwanted waste because it causes air pollution and ground congealment, and it is needed great efforts and financial support to disposal it. In this study, the WCKD was used partially instead of limestone as a filler in the asphalt mix, where it was used by ratios of 0%,25%,50%,75% and 100% from the weight of limestone. An evaluation of the mechanical characteristics was conducted by carrying out Marshall test and Indirect Tensile test, and the results showed that the increase in the WCKD percent reduces the asphalt mix density and increases the percentage of air voids, while the other characteristics (stability, Marshall Stiffness, flow and Indirect Tensile Strength) increase when the WCKD ratio is 25% and 50%. These those characteristics start decreasing when the WCKD ratio was 75% and 100%. The study showed that the optimum ratio of the WCKD is 50% from the limestone weight, and the WCKD cannot be used as a filler entirely in asphalt mix, but it can be used partially.
Abstract
The cash flow forecasting is beneficial for the project in both the tender stage and during the project construction progress, where the contractors want to make sure that their planned cash funds is sufficient to cover any possible financial deficit of the project. This research aims to find out minimum fund needed for highway projects in Iraq required by the contractor to maintain the progress of work under some circumstances and effects of the shortage of fund, particularly in case of payment delay, in addition to the implication of the payment delay. Data from record files of 9 highway projects in Iraq, of the unit price type contracts. It was found that the minimum fund required is 20.944 percent of the contract value of three months delay . The minimum fund required for those projects is directly proportional to the time of payment delay. The minimum fund required for projects is represented in a linear equation as a function of payment delay time, such equation would help the contractor to estimate the future amount of minimum fund required for any delay in months. Interim profit is calculated for the purpose of comparison with the expected profit for the purpose of exploring the consequences in case exceedance. Because of the use of unit price contracts in the implementation of highway projects in Iraq, it did not cause the appearance that the contractor receives large profit at early stages of the project. The delay in payment leads to negative results, including the delay in the project, reduces the level of performance of the contractor which is negatively affects project, reduce the quality of implementation and, increased cost of the project in case of the contractor to claim compensation for the damage, as well as the occurrence of a difference in currency and inflation due to the time difference between the payment date and the actual date.
Abstract
The role of strategic planning is particularly important in the development of trends graphic appropriate in the distribution of land uses for the city according to their importance and role in the development of the city. From this standpoint the idea of search to give the application of an analytical about how to adopt him graphical to insert the style of strategic planning and steps concatenated to give the relative importance of the distribution of applications and their role in the city's development in the future. two methods have been used in research assays are the factor analysis for the purpose of diagnosis and urban style quartet analysis SWOT developer + AHP for the purpose of determining the development priorities of the city and graphic orientation. Search concluded the conclusions and recommendations of the group serve the decision-makers and planners note that the study area to a city in Anbar province, Iraq (HIT) as a case study.
Abstract
Initial delineation of prospecting zones of groundwater was conducted in the present studyusing remote sensing and geographic information system (GIS) techniques. It has been preparingan integrated geographic database of spatial and non-spatial data for the study area. The spatialdata were generated by using image processing software (Erdas 8.3) and GIS software (Arc view3.3) enhanced by real frequent field visits of the study area. These data include: surface featureswhich give a direct and indirect indicators of the existence of groundwater and affect to thegroundwater movement such as hydrogeomorphological, drainage density, slope, landuse andsoil maps. The non spatial data were derived primarily from real views during field visits to thestudy area and from the existing writing or previous studies. All the data generated were saved inthe GIS databank for the purpose of digitization, computational and generate the best possibleoutput results to determine the extent of possible areas where the water that exists for the purposeof prospecting. Results showed that more areas could be have very good categories of prospectzones are the southern parts of the study area, which covers about 375 Km2 while the northernareas, which covers about 164 Km2 of the study area are grouped as runoff zone. Accordingly thepossibilities of the presence of groundwater are poor to negligible in this zone. The current studydemonstrated that a remote sensing and GIS technique are very effective tools that can give theinitial predictions on the presence or probability of the presence of ground water in areas whichhave the same considered geological deposits for the study area.
Abstract
In this paper, turbulent forced convection of nanofluid flow in channel with isoscelestriangularbaffles is numerically investigated over Reynolds number ranges of 5000-10000.One baffle mounted on the bottom wall of channel and another mounted on the top wall.Al2O3-water nanofluid with nanoparticles volume fraction of 4% and nanoparticles diametersof 25 nm is used. The governing continuity, momentum and energy equations as well as thelow Reynolds number k-ε model of Launder and Sharma have been solved using finitevolume method. The effect of baffle height, baffle distance as well as Reynolds number onthe flow and thermal characteristics have been presented and discussed. It is found that theenhancement ratio of the average Nusselt number as well as the fraction factor increase withincreasing in the baffles height. It is also found that the enhancement ratio of the averageNusselt number increases as the distance of top baffle decrease. Furthermore, the bestthermal-hydraulic performance of channel with triangular baffles using nanofluid can beobtained at baffle height of 2.5 mm, distance of the top baffle of 40 mm and Reynoldsnumber of 5000.