Journal of Engineering

This paper presents a design of a broadband thin metamaterial absorber (MMA) that provides a wide bandwidth with a compatible overall size. The designed absorber consists of a combination of an octagon disk and a split octagon resonator to cover the Ku and K bands' frequency range. The absorber uses cheap FR-4 material with a thickness of 1.6 mm and an overall unit cell size of 6.5×6.5 mm. CST Studio Suite was used for the simulation, which showed an absorption bandwidth of 14.4 GHz over a frequency range of 12.8-27.5 GHz with more than 90% absorption. The working principle of the structure was analyzed through input impedance, surface current, and the electric field. The proposed absorber was compared with recent MMAs in the literature, showing the widest bandwidth and highest absorption value, making it a good candidate for RADAR applications.

This paper investigates the deasphalting process of Iraqi atmospheric oil residue using different solvents, including light naphtha, n-heptane, and n-hexane. The oil residue from Al-Dura refinery, with specific gravity 0.9705, API 14.9, and 0.5 wt. % sulfur content, was treated under various operation conditions such as temperature, solvent concentration, solvent-to-oil ratio, and duration time1. The study examines the effects of these parameters on asphaltene yield. Results indicate that an increase in temperature enhances asphaltene extraction for all solvents1. The highest reduction in asphaltene content was achieved with hexane solvent at 90°C and a 4:1 solvent-to-oil ratio, yielding 93% asphaltene. The highest recorded API value was 32 using n-heptane solvent at 15:11

This study aims to identify the notion of Post-Occupancy Evaluation (POE) pertinent to the performance of three general hospitals constructed inside Sulaimani City, tracing the relationship between the quality of the indoor environments and medical staff (doctors and nurses) satisfaction level. Using some indoor environment elements in the right way will positively influence the mood, stress level of the medical staff, and patient recovery as a result. The POE toolkits (AEDET and ASPECT) have been implemented on targeted wards at the selected hospitals. AEDET and ASPECT questionnaires were distributed among 152 medical staff to obtain their perspectives. In total, 112 valid questionnaires were received. The medical staff at tested hospitals were generally satisfied with the quality of newly built hospitals' indoor environment. The results have shown that exploring medical staff experiences can expose factors that affect their satisfaction levels. Also, the findings reveal that the building's physical quality can be vastly related to the fulfillment of the medical staff's satisfaction. Moreover, the findings underline the role of the quality of the indoor environment in increasing medical staff's satisfaction levels, informing design decisions. Additionally, the persuasive associative outcomes have proven that POE (AEDET and ASPECT) will be pertinent as a tool to the building's physical quality.

This paper investigates the impact of slit weir dimensions and locations on the maximum scour depth and scour area created upstream. A total of 48 experiments were conducted using a slit weir model with a 110 mm slit opening installed at the end of the working section in a laboratory flume. The flume was 10.0 m long, 30 cm wide, and 30 cm deep, with a 2 m working section and a mobile bed with 110 mm in thickness. Two types of nonuniform sand (with geometric standard deviations of 1.58 and 1.6) were tested separately. The weir dimensions and location were varied with flow rates, which were changed from 2.6 to 8 l/s. The maximum scour depth and scour area recorded were 72 mm and 32357 mm², respectively, when the slit height, flow rate, and D50 of the movable bed were 110 mm, 8 l/s, and 0.3 mm, respectively.

This research aims to develop a new formula to evaluate the sediment capacity in the upstream part of Al-Gharraf River. The study reach lies in Wasit province with a distance equal to 58 km. The selected reach of the river was divided into thirteen stations. At each station, the suspended load and the bedload were collected from the river during a sampling period extended from February 2019 till July 2019. The samples were examined in the laboratory with a different set of sample tests. The formula was developed using data from ten stations, and the other three stations were used for validation. The determination coefficient, root mean square error, and average relative error values were equal to 0.987, 0.97 kg/s, and 7%, respectively. The values of the sediment load that resulted from the formula were close to the results of the HEC-RAS model from a previous study, with determination coefficient, root mean square error, and average relative error values equal to 0.988, 0.88 kg/s, and 7%, respectively, for the simulated model.

This paper aims to determine the causes of variation orders in projects performed between 2007-2014 in Erbil governorate projects. Data was collected from contract documents and questionnaires given to engineers involved in executing these projects1. The study seeks to identify the most significant causes of delays by assessing the common causes of delays in terms of frequency, severity, and important indices of owners, consultants, and contractors related to the implementation of public construction projects in Erbil Governorate. The results showed that the ranking of overall causes of variation order from highest to lowest was "Contractor's financial difficulties," "Change of plans or scope by owner," "The required labor skill are not available," "Differing site conditions," "Owner's financial problems," "Design change originated by owner," "Errors and omissions in design," "The required equipment and tools are not available," "Inadequate working drawing details," and "Change in design by the engineer or consultant"1. The source of "Errors and omissions in design," "Inadequate working drawing details," and "Change in design by the engineer or consultant" is the consultant.