Tikrit Journal of Engineering Sciences

The effects of limestone dust and superplasticizer upon the permeability, mechanical properties and durability of concrete exposed to sulfuric acid have been investigated. The properties of admixtured concrete and conventional concrete are compared. The coefficient of permeability of admixtured concrete was lower than that of normal concrete by 91.44%. The results indicated that the mechanical properties (compressive, splitting and flexural) strengths of superplasticized limestone dust concrete were higher than of normal reference concrete at all ages of concrete. The compressive strength of superplasticized concrete containing limestone dust were 46.94%, 49.48% and 47.59% more than that of reference concrete at ages 28, 60 and 90 days, respectively. The decreasing ratios in compressive strength of normal and superplasticized limestone dust concrete were (21.41%, 55.73% and 65.80%) and (20.46%, 43.81% and 54.20%) at 28,60 and 90 days of exposure to sulfuric acid, respectively.

This study is an application of optimization method to the structural design of circular silo, considering the total cost of the silo as an objective function of the properties of the silo and stored materials (unit weight of stored materials, angle of inclination of hopper wall, height of silo, height of hopper and silo diameter), as a design variables. A computer program has been written to solve numerical examples using the ACI code equations and all new requirements and criteria in concrete design. It has been proved that the minimum total cost of the silo increases with the increase of the angle of internal friction between stored materials, the coefficient of friction between stored materials and concrete, and the number of columns supporting hopper.

The present paper describe the design of an interface for measuring electric conductivity of different materials. It is designed and built an interface circuit consists of three analogue / Digital converters and its accessories to engage it with Microcomputer through the card of parallel port of printer. The main aim of building this circuit is to measure the electrical properties such as voltage, current, and then electric conductivity. The operating programs for this circuit runs under MSDOS environment for the sake of controlling its operation and calculating the required results later.

When possible, existing highway levels of service should be monitored by field measurements. As is the case with all fieldwork, traffic measurements are relatively expensive; they take time, personnel and equipment This research look after the feasibility of developing an acoustic sensing model to monitor the traffic flow at the highway sections instead of continuous counting of volume or other method of traffic monitor and surveillance devices. Vehicle tires radiate the major source of road noise. These phenomena can be used by cross-correlating the acoustic responses from roadside microphones with highway measure of effectiveness. The results demonstrated the feasibility of detecting LOS in the acoustic manner. The statistical regression technique gives power correlation model between the noise level as Noise Equivalent level or Noise Pollution Level and the density on the road sections. Other linear correlation models can be seen between these noise levels and the Level of Service of the highway but with less significant. This noise measurement receiver continually measures noise levels and can give around-the-clock picture of LOS variations at highway section This model allows the designer/planner to obtain quickly the first approximation of the expected LOS.

The optimum conditions of bubble column would be the ones that enhance mass transfer and this is accomplished by maximizing gas-liquid interfacial area. In the present work the effect of electrolyte concentration (aqueous solution of sodium chloride NaCl 0.005-0.015 gm/cm3) on bubble size, gas-liquid interfacial area and gas holdup at various superficial gas velocities (0.35-0.312 m/s)) in bubble column was studied. A series of experiments were also performed for air – distilled water system at various superficial gas velocities. The results for the two systems were compared and show a significant difference on gas-liquid interfacial area, bubble size and gas holdup. Digital camera for bubble size measurements was used and the fractional gas holdup was estimated using bed expansion. Correlation based on dimensionless groups for the prediction of bubble size, gas- liquid interfacial area and gas holdup is suggested. An agreement with available data was found

Graphite substrate lead dioxide (GSLD) was used to make a suitable anode for the production of potassium bromate from potassium bromide. This anode has been used successfully in the presence of certain addition agents (like potassium dichromate) as a replacement for graphite anode. A laboratory electrolytic cell was designed to produce of potassium bromate. A solution of potassium bromide (240 g/l) and potassium bromate (20 g/l) is electrolyzed in batch wise. The effect of anodic current density, temperature, and starting PH of electrolyte on the current efficiency of bromate formation was studied. High current efficiency of about 92 – 94 % was obtained by using (GSLD).

Quality assurance as a cultural standing point and economic role become more essential in the view of the new activation of the Iraqi Construction Sector. A comprehensive view of local factors must be considered side by side with the international development issues. This paper discusses the results of obtaining construction managers consensus opinion on factors to improve quality in the construction projects of governmental contracting companies. With the aid of Nominal Group Technique a consensus opinion of 100 construction managers in the Ministry of Construction and Housing is obtained on 25 factors sudjested by them to improve quality on their projects together with the relative importance of each factor. A Pareto analysis is carried out to show the weight of contribution of each factor and it was found that basic wages and quality related incentives together with obligations and delegations to construction project managers are the most important factors. The factors that have the same source of problems were also combined and categorized into five areas where it was found that satisfaction and quality knowledge together with instructions and procedures are the most critical areas. These findings are compatible with the new philosophy of total quality management.

The aim of this research is to computerized design of thread forms (ISO Metric thread) by converted geometrical description of thread forms elements into mathematical equation which have well coherency with one of most popular (CAD) format file that is Data Interchange Formats File (DXF). The developed (CAD) part of the system of thread forms designs allows automatic thread forms drawing generation using the AutoCAD Rel.2000 package thus by using (DXF). The developed system was tested and showed beneficial results when applied to thread forms design and found the capability to obtain thread forms in three dimensions with reduced time and efforts and high accuracy.

The present study is aimed to compare between the effect of the modified isothermal annealing with conventional full annealing and normalizing on the properties of medium carbon steel by full annealing and normalizing tensile test and otherdisclike shape specimens by heating them at (860Ċ) for (15min); followed by slowly cooling inside furnace for the former treatment and by air cooling for the later to room temperature. The modified isothermal annealing was conducted by heating eight group of specimen (each groups includes a tensile and adisclike shape specimen ) respectively at (860Ċ) for (15min) ,then slowly cooled inside furnace to different temperatures(760,700,600,560,460,380,340,and 260) Ċ then each group issoaked at one of those temperatures for an (1hr), then air cooled to room temperature .Larger (σT) which exceed (800 Mpa) and(VHN) values of the treated specimens at (760Ċ) were obtainedwhen compared with those obtained by normalizing. While an increase was took place in value of the treated specimens ∈%at (260Ċ) over its value when full annealed , hence the formability was improved by treating at. (260Ċ) isothermallywith a reduction in consumed electric energy because of the shorter thermal cycle. Also the toughness was considered by evaluating the restricted areas under stress – strain curves. Finally the resulted variations in microstructures were observed by optical microscope.

The sheet metal forming is defined as the ability of metal to deform plastically (stretch forming) without necking or fracture. To control the sheets forming operation failure a diagram is used , in which the ; accepted forming , failure and critical regions are shown.This diagram is known as “Forming Limit Diagram”(FLD) . It is considered as an important tool todetermine the formability of sheet metals . The forming limit diagrams for Aluminum , low carbon Steel and Brass were constructed experimentally as received and after annealing (with and without lubrication). Results have shown that the forming limit diagram for Brass was the highest and for Aluminum was the lowest. Annealing and lubrication have increased FLD for all metals in different quantities . Highest values of strain limits were appeared in FLD using both annealing and lubrication in the same time (widening limit curve) specially in brass .