Journal of Engineering

This work presents a neural network-based cost estimating method, developed for the generation of conceptual cost estimates for total building and electromechanical systems in building projects, by using eight parameters available at the early design phase. The model establishes a methodology that can provide an economical and rapid means of cost estimating. Eighteen light-rise building projects, built between 1996 and 2009 in Middle East countries, were used in this study. The performance of developed cost models was tested against costs incurred by projects not used in training of those models. Results show the mean absolute percentage errors (MAPE) are between 1.51% and 4.771% for the five networks, and the maximum/minimum deviation of the cost estimation is 10.2/0.17. These figures are considered good cost estimation at the early design stage.

This paper explores the application of high technology systems in building construction to mitigate the impact of external climatic conditions. The integrative approach emphasizes employing systematic solutions to enhance building resilience and sustainability. The study reviews various technological advancements and their effectiveness in creating adaptive and energy-efficient structures. By analyzing case studies and real-world applications, the research highlights the potential benefits and challenges of integrating high-tech solutions in modern building projects.

This paper explores the application of artificial neural networks for estimating the productivity of ceramic walls in construction. The research highlights the need for complex mapping of environmental and management factors to productivity. A generic description of the artificial neural network model is provided, followed by summarized factors affecting ceramic labor productivity. The developed neural-network model uses input data from experienced superintendents employed by a leading construction general contractor. Test results show that the ANN approach can produce accurate estimates with limited data-collection effort, making it a potential efficient tool for construction productivity estimation.

Reinforced concrete slabs with openings are usually designed with help of traditional rules proposed by building codes. Such methods introduce limitations concerning size, location of openings and magnitude of applied loads. Furthermore, there are some traditional approaches to strengthen reinforced concrete slabs with openings which can be either cumbersome or expensive. This paper studies variable locations of an opening with respect to a central column in reinforced concrete flat plates, and presents a good approach to strengthen this opening by using steel plates. Nine reinforced concrete flat plates are cast with dimensions (length, width and thickness) equal to (850, 470 and 50) mm) using a single concrete mix with average compressive strength (fcu) equals 30 MPa. Each slab contains a square cross-section opening (side length =75 mm) and supported by a central square cross-section column (side length =75 mm). The variables of this study are: the type of opening (with or without strengthening) and the clear distance between the opening and the column which takes the values (0.0d, 2d, 4.5d and 7d), where d is the effective depth. The specimens are tested over a simply supported span at four edges. The test results show that, the ultimate load reaches the maximum value for slab without opening while this load reaches the minimum value for slab with a non-strengthening opening and lies in the pattern of the failure zone (where the clear distance between the column and the opening equals 4.5d). When a comparison is made between the test results ,it is concluded that ;strengthening the slab opening with steel plates causes increasing in the ultimate load by (19.44 ,19.51 ,35.13 and 13.46) % for the specimens (0.0d ,2d ,4.5d and 7d ) respectively.

Pilot-scale dead end microfiltration membranes were carried out to determine the feasibility of the process for treating the oily wastewater which discharge from some Iraqi factories such as power station of south of Baghdad and the general company of petrochemical industries. Polypropylene membranes (cylindrical shape) with different pore diameters (1 and 5 micron) were used to conduct the study on micromembrane process. The variables studied are oil concentration (100 – 1000 ppm), feed flow rate (20 – 40 l/h), operating temperature (31 – 50°C) and time (0 – 3 h). It was found that the flux increases with increasing feed flow rate, temperature and pore size of membrane, and decreases with increasing oil concentration and operating time. It was found also that the effect of feed oil concentration has the greatest effect on the fouling of membrane among other variables. The percent rejection of oil improved significantly with decreasing oil concentration but decreased with increasing feed temperature, pore size of membrane and operating time. Feed flow rate has slightly effect on oil rejection. The type of oil used in this work is 20W-50 gasoline and diesel engine oil. A general model of dead end filtration mode has been successfully evaluated to explain fundamental mechanisms involved in flux decline during dead end microfiltration of oily water emulsions. Analysis of the fall in flux with time for the polypropylene membrane (5 μm) indicates that intermediate and standard pore models give the best prediction for experimental behavior. Empirical correlations for the prediction of the flux and percent reject of oil were determined in this study. These equations have the correlation coefficient 98.87% and 91.49% respectively.

This research was conducted using ceramic microfiltration membrane for treatment of oily wastewater in the pilot-scale dead-end filtration system designed in the laboratory under the influence of conditions of feed flow rate 15-35 l/h, feed temperature 32-48°C, oil feed concentration 300-1200 ppm, feed solution pH 2.6-9.8. The influence of these conditions on the permeate flux rate and oil rejection percent were investigated. Experimental results indicated that when feed flow rate increased to 35 l/h permeate flux rates increased to 100 l/m2.h and oil rejection percent decreased to 70.1%, and when feed temperature increased to 48 ºC permeate flux rate increased to 62 l/m2.h and oil rejection percent decreased to 56.44%. But when oil feed concentration increased to 1200 ppm permeate flux rate decreased to 17.2 l/m2.h and oil rejection percent increased to 99.7%. Also basic feed solution (pH=9.8) gave high permeate flux rate (44.51 l/m2.h) and low oil rejection percent (84%) in comparison with acidic feed solution (pH=2.6) which gave low permeate flux rate (26.42 l/m2.h) and high oil rejection percent (99.46%). Four classical models were investigated to flux decline and the results showed that the experimental data was consistent (R2 = 0.9883) with the complete blocking filtration model.

In this paper a robust governor has been designed using H∞ techniques to replace the conventional governor of the steam turbine of the power system to regulate the frequency of the power grid. The robust governor is synthesized using state-space approach with time variations, neglected dynamics, and constant main steam pressure are considered in the design process. The proposed approach ensures internal stability, satisfying both frequency and time domains requirements, and obtaining minimal performance H∞-norm of the closed-loop system in one burden. The simulations are carried out using MATLAB and the results show that the overall system output performance can be improved using the proposed H∞ robust governor.

Engineering education should involve practical laboratory to support theoretical foundation and develop student skills. These hands on laboratories have some disadvantages such as expensive, supervision required, time and place restrictions. This paper presents design and evaluation of a web based virtual laboratory for teaching Digital Signal Processing (DSP) to undergraduate students in Electromechanical Engineering Department at the University of Technology. The laboratory experiments includes classification of signals, sampling theorem, Fourier series, complex Fourier series, Fourier transform, inverse Fourier transform, discrete Fourier transform, Fast Fourier Transform (FFT),convolution , Z-transform, and digital filters. Graphical User Interface (GUI) feature of MATLAB have been used to provide students with a friendly and visual approach in specifying input parameters while Hyper Text Markup Language (HTML) was used to illustrate theoretical foundations. The questionnaire survey and five point Likert scale are utilized in performing evaluation. Results of this evaluation showed that the proposed virtual DSP laboratory was helped students in DSP concepts, made positive effects on students’ achievements and attitudes when compared to traditional teaching methods.

This study focuses on estimating runoff volume and peak runoff for the Goizha-Dabashan watershed (2.02 km²) using remote sensing techniques. The HEC-1 model, Rational method, and Soil Conservation Service curve number method (SCS-CN) were employed. Satellite images from Landsat-7 (ETM+) were used to develop land use and soil type maps. The watershed was delineated using a Digital Elevation Model (DEM) with a 10 m resolution and WMS 7.1 software. The runoff coefficient was calculated using the inverse of the Rational equation, and manual calibration was performed until the Nash-Sutcliffe coefficient provided the best results. The study found that the curve number method was more effective than the Rational method for estimating peak runoff discharge.

This study investigates the performance of a novel pilot-scale, batch recycled, flow-through cell with a stainless steel tubes bundle cathode for the removal of cadmium from simulated wastewaters. The electrochemical reaction involved the cathodic reduction of Cd+2 using 0.5 M sodium sulfate as the supporting electrolyte. Parameters analyzed included different initial Cd+2 concentrations (50, 100, 200, 300, 400 ppm) and different electrolyte flow rates (100, 200, 250, 300, 350 L/hr). The overall empirical mass transfer correlation was found to be: Sh = 0.051 Re^0.859 Sc^1/3 for 5 < Re < 20 and Sc = 649. Experimental results showed good performance of the cell and its adequacy in removing Cd+2 from simulated effluents.

This work presents a neural network-based cost estimating method, developed for the generation of conceptual cost estimates for total building and electromechanical systems in building projects, by using eight parameters available at the early design phase. The model establishes a methodology that can provide an economical and rapid means of cost estimating. Eighteen light-rise building projects, built between 1996 and 2009 in Middle East countries, were used in this study. The performance of developed cost models was tested against costs incurred by projects not used in training of those models. Results show the mean absolute percentage errors (MAPE) are between 1.51% and 4.771% for the five networks, and the maximum/minimum deviation of the cost estimation is 10.2/0.17. These figures are considered good cost estimation at the early design stage.

This paper presents numerical investigations of unsteady natural convection heat transfer through a fluid-saturated porous media in an inclined cylindrical enclosure. The governing (3-D) Darcy-Boussinesq equations were solved using the finite difference method. The momentum equation of flow was solved by the Relaxation method, and the energy equation by the Alternating Direction Implicit (ADI) method. The problem was analyzed for modified Rayleigh numbers ranging from 50 to 300, inclination angles of 0°, 25°, 45°, 60°, and 90°, amplitude of sinusoidal temperature (0.2, 0.4, 0.8), and period (0.005, 0.01, 0.02). Results indicate an increase in heat transfer with increasing Rayleigh number, time, amplitude, angle of inclination, and period. Average and local Nusselt numbers were calculated, showing maximum temperature and velocity at an angle of 45°, indicating a strong buoyancy force effect on convective flow.

This paper is a study of the effect of natural saliva (oral cavity) and a fluoride mouthwash on dental amalgams. Two types of electrodes were made: the first was of a high copper amalgam while the second was made from a low copper amalgam. They were immersed in two types of electrolytes for twelve hours, and the whole galvanic cell was connected to a computer via a potentiosat. Their corrosion currents, corrosion voltage, and corrosion resistance were recorded and compared to find which medium usually has the most severe effect on the amalgams' corrosion.

This paper investigates the behavior of forced convection heat transfer characteristics through and over a porous layer near a heated flat plate with variable temperature boundary conditions. Two cases are studied: linear temperature variation with position along the flat plate and sinusoidal temperature variation with time. The flow field in the porous region is governed by the Darcy-Brinkman-Forchheimer equation, while the thermal field is governed by the energy equation. Solutions were obtained using a finite difference method through a stream function-vorticity transformation. The effects of various dimensionless parameters, such as Darcy number, Reynolds number, Prandtl number, and inertia parameter, were explored. Results indicate that the local Nusselt number on the flat plate increases with increasing non-dimensional values of period and amplitude individually.

This study focused on treating wastewater to remove phosphorus by adsorption onto natural and local materials. Burned kaolin, porcelanite, bauxite, and limestone were selected to be tested as adsorption materials. The adsorption isotherms were evaluated by batch experiments, studying the effects of pH, temperature, and initial phosphorus concentration. The results showed that at pH 6, temperature 20°C, and 300 mg/l initial phosphorus concentration; the sorption capacity was 0.61, 9, 10, and 13 mg/g at 10 h contact time, for burned kaolin, porcelanite, limestone, and bauxite respectively. As the pH increased from 2 to 10, the removal efficiency for the materials differed in behavior. The removal efficiency increased from 40 to 90% for limestone, and decreased from 60 to 30% for porcelanite. As for bauxite, it increased from 60 to 90% reaching pH 6 then decreased to 30%. Burned kaolin showed the lowest adsorption capacities in these tests. The adsorption isotherms showed that the Langmuir–Freundlich model significantly correlated the experimental data for porcelanite and bauxite, whereby the Freundlich model was best for limestone. The Freundlich and Langmuir–Freundlich models both fit for burned kaolin. The results show that it is possible to adsorb phosphate from wastewater onto natural Iraqi materials and their ability could be ranged as limestone > bauxite > porcelanite > burned kaolin.