Al-Nahrain Journal for Engineering Sciences

Total hip replacement (THR) is an elective surgical procedure with the primary indication being pain relief. The aim of this study is to analyze gait dynamics for patients after they underwent a unilateral THR surgery and compare it with normal parameters. To investigate the gait dynamics a gait analysis was performed on five patients after they underwent a unilateral THR surgery; only two of them were examined before the surgery. The gait analysis was performed using a digital video camera with two force plates. Kinematics data were obtained from 2D trajectories of seven passive markers using SkillSpector software. MATLAB software has been used for inverse dynamics computation. General gait parameters, Harris Hip Score, joints’ angles, forces, moments and powers were obtained during gait cycle. It was found that the average of improvement in Harris Hip Score (for four patients who were examined 1.5, 2.5, 3 and 9 months after surgery) is 61.8 points, which is an indication of pain relief. In the other hand, the general gait parameters were found slightly lower than normal after THR surgery. The average hip reaction force was found to be 2.988 N/BW, which is within normal range. Also, the average of maximum hip extension and maximum hip flexion angles were found to be 25.69 and -13.524 degree respectively, which both are within normal ranges. Furthermore, hip, knee and ankle moments and powers results showed some abnormality. Therefore as a conclusion, patient satisfaction and functional improvement are not related to general gait parameter. And it is not unusual that gait mechanics improvement would not reach normal after months of recovery. Also, the results of gait dynamics which are from the engineer’s perspective are compatible with Harris Hip Score, which is from the physician’s perspective, in quantifying surgical results and subsequent recovery progress.
Keyword: Total Hip Replacement, Gait cycle, Gait dynamics, Force platform, Harris Hip Score, General Gait Parameter.

The microstructural analysis and electrochemical measurements tests were used to investigate the behaviors of (TiO2) and (HAp)-coated Ti-6Al-7Nb alloy in the SBF solution .By using RF sputtering, a thin TiO2 layer coated the substrate, while a thick layer of HAp coated the outer side of surface. The generated middle layer consist of the composite of TiO2 and HAp which is by AFM characterized as uniformly distributed coating system with nano size. The images of the scan electron microscopy (SEM) shows that there is no any cracking observed in the outer layer of tested samples due to the use of thin film TiO2 as mid lead to reduce the difference in the thermal expansion between the HAp material and Ti-6Al-7Nb substrate .The HAp upper layer significantly improve the bioactivity of the Ti-6Al-7Nb alloy. In this study, the bonding strength and the corrosion resistance was improved by using thin layer of TiO2. From electrochemical impedance spectroscopy (EIS) study Bod plot, the composite layer of TiO2 and HAp was suggested by the capacitive act as barrier layer coated substrate and prevent the relays of the ion from metallic. The results shows the values of Rox (309.2 kΩ cm2)are greater than for Rct(19.2 kΩ cm2), by assumes the presence oxide film increases for coated substrate are greater than that of uncoated, which is a result of the presence of coated film that improve the corrosion resistance of the sample.

The control of quenching process has been investigated in this study by developing a quench system design to simulate the quenching process and measure the time – temperature history inside the sample during the cooling stage. The main purpose of this quench system is to evaluate the quench power of different quenchant at different conditions (type, temperature and agitation).
A stainless steel sample was used with a suitable measurement as a probe in designing this quench system.
The performance of two of quenchants (water and brine) with different conditions was investigated, and the designed probe was used to illustrate the effect of quenching parameters (quenchant type, temperature and its agitation) on cooling curves and cooling rate.The quenching system has proven its ability to work effectively and the results showed that heat transfer properties were significantly affected by quenchant parameters

In this study the friction stir lap welding was carried out by a new technique (diffusion bonding phenomenon) between (AA1100 and low carbon steel C10 sheets of 3mm and 1mm thickness respectively. These alloys have difference ranges in melting temperature and other physical properties. Different parameters were used: tool rotation speeds (630, 1250) rpm, travel speeds (80, 32) mm/min. and pin length (2.8,3) mm using cylindrical threaded pin. Many tests and inspections were performed such as tensile shear test and X-Ray diffraction tests. Microhardness and microstructure observations were conducted by using optical and SEM. The above tests were used to evaluate the weld quality and joint efficiency under different welding parameters. Best result for FSLW by diffusion phenomenon appear in (low carbon steelC10 / AA1100-H112) joint at 1250rpm in 32 mm/min. with 2.8mm pin length and the maximum tensile shear strength was (3.9)KN.It was found that the highest micro hardness was (138HV) at the interface between the low carbon steel and AA1100.

There are many patients who face a lot of things that hurt the knee joint. Knee replacement is the best solution to these problems. This research was based on reducing the vibrations of daily activities as measured by the frequency of foot and knee for the patient for three cases when the bare foot, sports shoes with ground air and sports shoes with ground air with silicon damping. Patient information for this work was of age, weight, height and leg length 48 years, 90 kg, 160 cm, 84 cm, respectively. The results was shown that the decline in acceleration results was in the case of sport shoes with ground air with silicon damping with 22.57%, while the decline in vibration results was in the case of sports shoes with ground air with -54.9%.

Pressure vessels are the heart of plants and oil refineries stations. In many engineering applications such vessels can be subjected to periodic loading either internally due to the charging and discharging process or externally due to the excitation from other nearby components such as pumps, compressors or from seismic. So that in spite of a good design according static assumption it may be critical in dynamics. In this work a horizontal pressure vessel with accessories subjected to liquefied petroleum gas pressure LPG is considered. Three models of different head types are investigated herein namely; Deep torispherical, Elliptical 2:1 and Hemispherical. The design and material selections are chosen as per ASME. For practical service many accessories are attached to the vessel such as manhole, supports, inlet and outlet opining. Finite Element method via ANSYS R18.2 is introduced for the numerical analysis. The fatigue life in case of fully reversed cyclic loading are estimated and located. Vibration characteristics such as mode shapes and natural frequencies for the lowest five modes are evaluated and compared. It is found that the fatigue life can be increased as higher as 180% for hemi- spherical head as compared with deep torispherical head pressure vessel and the lowest four natural frequencies are nearly identical for all models, however significant change observed in the fifth natural frequency

In this work, the control of Translational Oscillations with a Rotational Actuator (TORA) system is presented in this paper. The optimal sliding mode controller is proposed to control the two DOF underactuated mechanical system. The nonlinear coupling from the rotational to the translational motion is the main problem that faces the controller design. The H2 sliding mode controller is designed to give a better performance if only sliding mode control is used. The results illustrate that the proposed H2 sliding mode controller can achieve the stabilization of the system with the variation in system parameters and disturbance

Abstract
In this work, the control of Translational Oscillations with a Rotational Actuator (TORA) system is presented in this paper. The optimal sliding mode controller is proposed to control the two DOF underactuated mechanical system. The nonlinear coupling from the rotational to the translational motion is the main problem that faces the controller design. The H2 sliding mode controller is designed to give a better performance if only sliding mode control is used. The results illustrate that the proposed H2 sliding mode controller can achieve the stabilization of the system with the variation in system parameters and disturbance.

Abstract
Liquid nitrate is an important method used to improve mechanical properties, one of these properties is resistance to fatigue. The aim of this study was to improve the fatigue resistance of the stainless steel 316L. The rotational bending method was used with constant and variable stresses at different times of (1, 3, 5) hours and at (530, 630) oC. These tests were performed before and after nitration.
The results showed that the depth of the nitride layer was (0.21, 0.33, 0.45) mm, increasing with time nitriding when the temperature was 530 oC. While the depth of this layer at a temperature of 630 oC (0.26, 0.39, 0.5) mm with increasing time. As a result of these processes, a layer of solid chromium nitrides and other phases of iron nitride were formed on the outer surface. These layers helped to inhibit the growth of the cracks and their progress in addition to the generation of pressure stresses on the surface leading to obstructing the progress of the cracks.
This study showed that the fatigue resistance was directly proportional to the increase in nitrate time due to the increased depth of the hardened layer, but this resistance decreased when the temperature was 630 oC due to the formation of brittle phase with low resistance

The objective of this study is determining the mixing and compaction temperature of the modified asphalt mixture. Results of binder tests showed that the addition of 3% SBS to control asphalt (PG 64-16) would achieve the desired performance level (PG 76-16) a performance grade that fits our climate with traffic loads. When using 5% SBS the performance grade of binder increased three grades (PG 82-16) and when increasing SBS content to 8% the performance grade increased four grades (PG 88-16). At shear rate of 500 (s-1), the modified asphalt viscosity can be obtained at different temperatures and the viscosity temperature curve can be achieved. As a result, the mixing and compaction temperature of modified asphalt can be determined to reach 0.17 ± 0.02 Pa.s and 0.28 ± 0.03 Pa.s for mixing and compaction, respectively. It is noted that SBS modified reached a viscosity of 3 Pa.s when 8 % additive. Additive contents above these values may not be suitable for good workability and pump ability according to Superpave specifications. While addition of 5% SBS with control asphalt, more than 3.7times at 135°C Increase the viscosity. Marshall Stability test indicated that the strength for the SBS specimens increases as compared to the conventional specimens. An increase of about 39%, 74%, 102%, was observed with 3%SBS 5%SBS 8%SBS modified binders, respectively. The Marshall test results for 8%SBS binders required compaction temperatures above 175°C need to keep up quality of HMA item while limiting natural effect amid development, these proposals are unsatisfactory Modified mixtures the 5% SBS modification was determined to be the maximum useful content. The Superpave method to estimate mixing and compaction temperatures show are not practical for use with modified binders. Also, it is observed that good agreement values between the average Marshall compaction temperature and the High Shear Viscosity Method (HSRV) and lower than Superpave methods Where the decline ranges from 15 ºC to 17 ºC.
Keywords: SBS, HMA Mixing And Compaction Temperatures, HSRV, Modified Asphalt Mixture

The heat exchanger is a device used to transfer heat energy between two fluids, hot and cold. In this work, an output feedback adaptive sliding mode controller is designed to control the temperature of the outlet cold water for plate heat exchanger. The measurement of the outlet cold temperature is the only information required. Hence, a sliding mode differentiator was designed to estimate the time derivative of outlet hot water temperature, which it is needed for constructing a sliding variable. The discontinuous gain value of the sliding mode controller is adapted according to a certain adaptation law. Two constraints which imposed on the volumetric flow rate of outlet cold (control input) were considered within the rules of the proposed adaptation law in this work. These are the control input is a positive quantity, and it limited by a maximum value. The maximum allowable desired outlet cold water has been estimated as function of heat exchanger parameters and maximum control input. The simulation results demonstrate the performance of the proposed adaptive sliding mode control where the outlet cold water was forced to follow desired temperature equal to 〖45〗^o. Additionally, the robustness of the proposed controller was tested for the case where the cold water inlet temperature is not constant, and also for the case of heat exchanger parameters uncertainty. The results were revealed the robustness of the proposed controller.

This research focuses on studying the importance of quality management system ISO 9001: 2015 and its impact on machinery breakdowns in the general company for the manufacture of wool and carpets in Hama for reducing the machines stops and thus increasing production quantities in the company. We did a field study in the company which a random sample of workers was interviewed in, taking into consideration the characteristics of the categories of workers.
We analyzed the data obtained from the workers by using statistical analysis program (SPSS19).
The statistical results have shown that there is a strong correlation between the quality management system ISO 9001: 2015 and machinery breakdowns, which necessitates giving greater attention to the ISO 9001standard by the company's management and seeking ISO 9001 certification to achieve high performance for the company under study

An investigation of performance response of two types of bearings such as Cylindrical Roller Bearing and bush bearing on evaporative cooler driven by DC motor of 1500 r.p.m, through studying many parameters like vibration response, temperature raise, humidity, sound level and total performance. high quality 3D positions X, Y and Z, vibration sensors type (ADXL335 accelerometers) with Arduino mega 2560 that interfaced with Lab-View program were used to measure changes in vibration amplitude and frequency. Two temperature sensors of type (LM35) were used to investigate the temperature raise in the bearings also with Arduino mega 2560 that interfaced with Lab-View program. For humidity a sensor of type DHT22 was used, also, a portable device was used to measure electricity consumption, rotary speed and sound level in the bearings of evaporative cooler. By replacing bearings all the parameters above wear measured then a comparison between them were made to find the best performance and operation of these bearings. The obtained results from the experimental work have clarified and explained by tables and figures. It has been found that the vibration of evaporative cooler in X, Y and Z-directions increased by using two cylindrical roller bearings than using two of bush bearings. The temperature of cylindrical roller bearings increased When running the evaporative cooler more than bush bearings. the noise of Evaporative Cooler by using both types of Bearings was almost same but with a little Reduce by using cylindrical roller Bearings. Which means the Evaporative Cooler has better Performance by using bush bearings than using cylindrical roller bearings.

Abstract
The depleting of the conventional sources of energy and the excess use of HCF components lead to the need for new techniques both for conservation of energy sources for the future and for decreasing the its harmful effects on the environment. This study investigated the adsorption capabilities of activated carbon. The adsorption of methanol on this substance was tested for their application in the adsorption refrigeration system based on solar energy.
Adsorption refrigeration system has been designed and manufactured with the energy source being solar energy. Methanol/activated carbon pairs have been used in experiments. The present work focused on the performance of the adsorption refrigeration system considering the temperature attained in the evaporator and the cooled spaced cabinet. The amounts of activated carbon used was (8 kg), while the amount of methanol were (1, 1.25, and 1.5) kg. The experiments were done in different days of the year. The amount of adsorption of methanol (as a result of decreasing the evaporator and cooled spaced temperature) was found to depend on the generator pressure and its increase as the primary generator pressure decreases. The best mass of methanol used was (1 kg) which give the lowest temperature obtained at the evaporative surface was ( 3.4 oC ) at the day ( 4/4/2017 ). The results shown that even in cloudy days there is a benefit from using such a system because the temperature attained is enough to start the adsorption process. The lowest temperature obtained at the evaporative surface was (3.4 oC) at the day (4/4/2017) for methanol mass of (1 kg) at an opening time of the valve between the evaporator and the generator (9:30am). The increase of methanol amount used in the experiment led to a good decrease in temperature attained in cooled spaced, but this is related to the time of connecting the evaporator and generator