Search

Low- and medium-carbon structural steel components face random vibration and dynamic loads (like earthquakes) in many applications. Thus a modification to improve their mechanical properties, essentially damping properties, is required. The present study focuses on improving and developing these properties, significantly dampening properties, without losing the other mechanical properties. The specimens used in the present study are structural steel ribbed bar ISO 6935 subjected to heating temperatures of (850, 950, and 1050) ˚C, and cooling schemes of annealing, normalizing, sand, and quenching was selected. The damping properties of the specimens were measured experimentally with the area under the curve for the loading and unloading paths experienced from the tensile test. Considering the effect of different parameters on the damping properties, such as heat treatment temperatures, cooling rates, and carbon content, the results show that the damping properties in the annealing process at different temperatures have interesting damping properties, among other processes. Also, the highest damping energy for the annealing cooling scheme was attained at a heating temperature of 1050 ˚C, irrespective of the carbon content. Finally, better damping properties for the medium carbon content of (0.299%C) is achieved for all types of heat treatment process compared with a low carbon content of (0.188% C); and, in general, with increasing carbon content from medium to low, steel response to heat treatment increases and better damping properties are obtained.

Numerous tests are recently conducted to assess vibration's role in accelerating the heat transfer rate in various heat exchangers. In this work, the enhancement of heat transfer by the effect of transfer vibration and inclination angles on the surface of a double pipe heat exchanger experimentally has been investigated. A data acquisition system is applied to record the data of temperatures, flow rates, and frequencies over the tests. A compound technique was adopted, including the application of a set of inclination angles of (0°, 10°, 20°, and 30°) under the effect of frequency of vibration ranging from sub-resonance to over-resonance frequencies. The results showed that the overall heat transfer coefficient enhances by applying the compound technique at all the working fluid's temperatures and flow rate ranges. The maximum increase in overall heat transfer coefficient occurs at an angle of 30° and the resonance frequency. Moreover, the effectiveness of the double pipe heat exchanger gradually expanded when temperature, inclination angles, and vibration amplitude rosed. But the effectiveness value declined as the hot working flow rate increased considerably. Finally, the enhancement factor demonstrated that the combined strategy (vibration frequencies and inclination angles) had been the most effective technique in improving and enhancing heat transfer and was superior to the other ways. Additionally, the extremes improvement in overall heat transfer coefficient, effectiveness, and enhancement factor are 183.4, 191, and 164.4 %. The improvement was situated at the resonance frequency with a 30° inclination angle.

When a vehicle is left parked in the sun for an extended period, the gathered heat causes damage to several interiors within the cabin and causes discomfort for people and animals left inside the car. In the present work, the effect of the orientation of a parked white minibus on temperature distribution and cooling load calculation is studied experimentally in an open environment. Two different cases were studied facing south and facing east. For several hours, the temperature inside the car cabin had been monitored and measured at five separate locations. The cooling load calculations are carried out based on the experimental measurements. The results show that the overheating of parked cars always happens as a result of the radiation load especially when a car has a large surface glass area. Also, the ambient load is directly proportional to the ambient temperature, and the total load related directly to radiation load reaches the maximum value of 2358.1 W at 3:00 pm for 1st case and 2118.3 W at 11:00 am for 2nd case which shows an increase of 11.32 %. Thus, these results emphasized the fact that the orientation of the parked car may considerably affect the temperature distribution and the cooling load of the car cabin. Also, the study may be considered an essential step in designing any assisted ventilation or auxiliary air conditioning system that may enhance the car cabin conditions even while the car’s engine was off (parked automobile).

Failures of the crankshaft-slider mechanism are the most reasons that affect the durability and operational reliability of the internal combustion engine. An accurate and sophisticated nonlinear dynamic model overcomes the obvious simulation errors of linearized models. The present work studies the effect of the non-conservative forces and nonlinear damping on the torsional vibration of single-cylinder internal combustion engines. Comprehensive dynamic modeling based on a developed expression for the instantaneous kinetic energy of the reciprocating parts and a general model of the overall kinetic energy of the system in terms of the inertia parameters were derived. The effect of variable inertia and nonlinear damping on the damped forced response of slider-crank assembly of the engine was investigated using the numerical integration method. The numerical results show that the phenomenon of secondary rolling excitation torque is well activated and gives arises to variation of frequencies and their corresponding amplitudes. Also, the amplitude of the external excitation torque is strengthened by the secondary excitation inertia torque and introduces multi resonance amplitudes phenomenon and widening the critical range of engine speed which results in producing of dangerous vibrational stress amplitudes. Also, the damped forced results indicate that the presents of damping lead to a vital reduction in the amplitude of torsional displacement and excitation torques. The present work aims to enhance nonlinear dynamic modeling and introduces more reliable design for reciprocating engine crankshaft assembly.

Liquefied petroleum gas (propane or butane) is a colorless liquid which readily evaporates into a gas. It has no smell, although it will normally have an odor added to help detect leaks. Liquefied petroleum gas is stored and handled as a liquid when under pressure inside an LPG cylinder. Liquefied petroleum gas cylinders are subjected to various tests to ensure their compliance requirements as per standard. This research studies the durability of welding and performance of base metal of L. P. G. home cylindrical in Kurdistan region. The experiments were carried out on three types of LPG cylinder using in Kurdistan regions A, B, and C and an unformed plate. To carried out the samples and tests during the research we depending on the standard tests for LPG cylinders. Three samples are extracted from each of LPG cylinders and unformed plate for each of tensile test, Bending test and Hardness test according to ISO 6892-2016 and ASME standards from each type of LPG cylinders and from unformed plate to examine the mechanical properties. In addition, chemical compositions also were carried out. These values are compared with standard.

Liquefied petroleum gas (propane or butane) is a colourless liquid which readily evaporates into a gas. It has no smell, although it will normally have an odour added to help detect leaks. Liquefied petroleum gas is stored and handled as a liquid when under pressure inside an LPG cylinder. Liquefied petroleum gas cylinders are subjected to various tests to ensure their compliance requirements as per standard. This research studied the durability of welding and performance of base metal of LPG home cylindrical in Kurdistan region. The experiments were carried out on an unformed plate and three types of LPG cylinder designated as A, B, and C and D. In this research standard tests for LPG cylinders were conducted. Three samples were extracted from each of LPG cylinders and unformed plate for each of tensile test, bending test and hardness test according to ISO 6892-2016 and ASME standards to examine the mechanical properties. In addition, chemical compositions also were carried out. These values are compared with standard.

In the present work, the behavior of thick-walled cylinder of elasto-plastic material (polymeric material) has been studied analytically. The study is based on modified Von-Mises yield criterion (for non metallic material). The equations of stress distribution are obtained for the cylinder under general cases of elastic expansion, plastic initiation and elastic-plastic expansion. A computer program is developed for evaluating the stress distribution. The solution is carried out for worst boundary conditions when the cylinder is subjected to the combination of pressure load, inertia load, and temperature gradient. The results are presented graphically in terms of dimensionless stresses and radius ratio. They indicate that the thermal and rotational loads are greatly influencing the stress distribution and the initiation of plastic zone, as well as the spreading out of the plastic zone. Moreover, it was found that the critical values of loads required for starting plastic deformation are determined by the amount of the applied load and the type of loading conditions, and it is found that the variation of stresses are greatly influenced by increasing of the temperature gradient at constant pressure and inertial loads than other increases in loading conditions.

In the present paper a low cost mechanical vibration shaker of rotating unbalanced type with uniaxial shaking table was designed and constructed in an attempt to provide opportunities for experimental testing and application of vibration in experimental modal analysis, stress relief of weldments, effect of vibration on heat transfer and seismic testing of civil engineering structures. Also, it provides unexpressive solution to enhance the knowledge and technical skills of students in mechanical vibration laboratory. The shaker consists of a five main parts shaker frame, shaker table, flexible support, drive motor, and eccentricity mechanism. The experimental results show that the amplitude of the shaker is increased with increasing the frequency ratio and the maximum value was attained near the resonance condition. Also, the magnitude of amplitude is increased with increasing the eccentric mass and eccentricity values. A reasonable agreement with theoretical results shows that the shaker can be used with reliable results in vibration testing purposes. Also, in this paper, the frequency ranges of the shaker were determined for constant displacement and for constant acceleration tests to satisfy all the frequency limitation requirements of the mechanical shaker.

In the present work, the behavior of thick-walled cylinder of elasto-plastic material (polymeric material) has been studied analytically. The study is based on modified Von-Mises yield criterion (for non metallic material). The equations of stress distribution are obtained for the cylinder under general cases of elastic expansion, plastic initiation and elastic-plastic expansion.A computer program is developed for evaluating the stress distribution. The solution is carried out for worst boundary conditions when the cylinder is subjected to the combination of pressure load, inertia load, and temperature gradient.The results are presented graphically in terms of dimensionless stresses and radius ratio. They indicate that the thermal and rotational loads are greatly influencing the stress distribution and the initiation of plastic zone, as well as the spreading out of the plastic zone. Moreover, it was found that the critical values of loads required for starting plastic deformation are determined by the amount of the applied load and the type of loading conditions, and it is found that the variation of stresses are greatly influenced by increasing of the temperature gradient at constant pressure and inertial loads than other increases in loading conditions.

In the present work a general dynamic behavior of non return valves subjected to jet flow is presented. The differential equations of valve motion and discharge were developed in a non-dimensional from, in terms of suitable dimensionless variables and parameters of the valve system. The derived equations are coupled nonlinear differential equations. Thus, a computer program was developed using a package called (MatLab) to solve these equations. The study shows that there are three types of the valve responses depending on the overall hydrostatic pressure difference and it is found that the valve vibrating at a constant limit cycle, which is leading to the failure of the system. It is also shown that the limit cycle frequency decreases with increasing the stiffness parameter and inertia factor. Finally the study shows that the losses factor has negligible effect on valve vibration and discharge.

Copyright of Journal of Engineering (17264073) is the property of Republic of Iraq Ministry of Higher Education & Scientific Research (MOHESR) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The bacterial isolates Streptomyces were obtained from the soil and cultivated in a wheat bran medium, which was used to produce the L–glutamate oxidase enzyme. The extracellular enzyme was then extracted using a cooling centrifugation process to obtain the filtrate that represents the crude enzyme. Afterward, the enzyme purification processes were carried out which included precipitation with ammonium sulfate as a preliminary purification step followed by dialysis to remove the salts. Next, ion-exchange chromatography and gel filtration were used to finish the purification process, and the enzyme activity was determined for each purification step. The results of purification of L-glutamate oxidase enzyme from streptomyces using ammonium sulfate showed that the specific activity was 8.25 units/mg protein with a saturation ratio of 60%. Moreover, the results of purification using a dialysis tube indicated that the specific activity was 9.5 units/mg protein. In addition, the result of purification using diethylaminoethyl cellulose ion column revealed that the specific activity was 25 unit/mg protein and the results of purification using gel filtration showed that the specific activity was 56 units/mg protein which was the best step in the purification process due to high specific activity of the enzyme. The optimum temperature and pH for the activity and stability of the enzyme were tested. Based on the findings, the optimum temperature for the activity of the enzyme was 37 °C. In addition, it was found that the optimum temperature range for the stability of the enzyme was 30-50 °C. Besides, the optimum pH for the activity was 7.0 and the optimum pH range for the enzyme stability was 5.0-7.0. [ABSTRACT FROM AUTHOR]

This investigational analysis exemplifies the design and test of diffuser at compressor inlet and nozzles at condenser outlet and expansion valve outlet in VCR with the help of Rl34a refrigerant. The diffuser with divergence angle of l5°, l7° and the nozzle with convergent angle l5°, l7° are designed for same inlet and outlet diameters. Initially diffusers are tested at compressor inlet diffuser is used with inlet diameter equal to exit tube diameter of evaporator and outlet tube diameter is equal to suction tube diameter of the compressor. Diffuser helps to increases the pressures of the refrigerant before entering the compressor it will be helps to reduces the compression work and achieve higher performance of the vapour compression refrigeration system. Then nozzles are testing at condenser outlet and expansion valve outlet, where as nozzle inlet diameter equal to discharging tube diameter of condenser and outlet diameter equal to inlet diameter of expansion valve. Extra pressure drop in the nozzle helped to accomplish higher performance of the vapour compression refrigeration system. The system is analyze using the Ist and IInd laws of thermodynamics, to resolve the refrigerating effect, the compressor work input, coefficient of performance(COP).. [ABSTRACT FROM AUTHOR]

Aims: The purpose of our study is to assess the role of high-resolution real-time gray-scale ultrasonography with ultrasound-guided fine-needle aspiration cytology (FNAC) in detecting malignant nodules in the thyroid gland. Settings and Design: It is a retrospective study of 25 patients (aged 16–63 years) who underwent high-resolution ultrasound (HRUSG) of the thyroid gland and ultrasound-guided FNAC from February 2017 till November 31, 2017. Materials and Methods: A total of 25 patients with thyroid nodules detected at ultrasound were included in this study. The characteristics of each nodule were determined. The results were then compared with FNAC (ultrasound-guided) findings. Statistical Analysis Used: Sensitivity, specificity, positive predictive value, negative predictive value and accuracy were used. Results: Of the 25 nodules examined, 5 (20%) were found to be malignant on cytology. Conclusions: Gray-scale ultrasound features of thyroid nodules are useful to distinguish malignant thyroid nodules from those with benign nodules. From our study, it is obvious that the HRUSG findings of hypoechogenicity, microcalcification, and poorly defined margins have high diagnostic accuracy for identifying malignant thyroid nodules. [ABSTRACT FROM AUTHOR]

A 24-year-old woman presented to the emergency department with profound icterus, which had not resolved with standard hepatoprotective measures (ursodeoxycholic acid, cholestyramine, I N i -acetyl cysteine). As both the skin eruption and icterus appeared concurrently, we considered progesterone-related cholestatic hepatitis coexisting with autoimmune progesterone dermatitis (APD). We hypothesize that progesterone-induced inflammatory oedema at progesterone-secreting biliary canaliculi may be the reason for cholestasis in drug-induced causes, and the APD in our patient might be an external inflammatory marker. [Extracted from the article]

This research examines the use of vibratory treatments to reduce residual stresses in small welded parts. In this experimental investigation, a post weld vibration treatment was applied to T- A106 steel pipe fitting specimens to study the effect of the treatment on the residual stress and the hardness of the material. The vibratory stress relief treatment was carried out at different vibration frequency. The results have demonstrated that post-weld vibratory stress relief of small size fittings is possible and residual stress may be relieved, and the treatment may be an alternative method for heat treatment especially when unchange in dimensions and material stability are required.

Human cystic hydatidosis (cystic echinococcosis) is a chronic zoonotic disease that results from infection with the dog tapeworm Echinococcus granulosus. In Egypt, cystic echinococcosis (CE) is recognized in slaughtered livestock by veterinarians, however, there is little information about human CE infection rates. We describe an immunological assay useful for the diagnosis of human cystic hydatidosis. Sera were collected from surgically confirmed hydatid cases (34), nonendemic subjects free from parasitic infection (20) and from subjects (109) infected with other helminths (Hymenolepis nana, Schistosoma mansoni, Fasciola hepatica and Ancylostoma duodenale). Hydatid cyst fluid (HCF) of camel origin was used as antigen in an ELISA format to measure total E. granulosus specific IgG antibodies and IgG subclasses. Sensitivity measurements of total IgG, and IgG1-4 were 100, 100, 79.4, 61.8 and 55.9%, respectively, whereas respective specificity reached 65.1, 97.7, 98.4, 96.1 and 83. 7%. The diagnostic value of measuring IgG1 (97.7%), as assessed by a rating index (J) for combined sensitivity and specificity, was superior to total IgG (65.1%) and IgG2-4 (77.8, 57.9 and 39.6%, respectively). These findings set the stage for field evaluation of the IgG1 assay in areas endemic with human cystic hydatidosis. [ABSTRACT FROM AUTHOR]

In this study, a correlation between an approximate analysis of beam vibration problem and experimental measurements of vibration property was achieved in an attempt to develop a simple and reliable experimental method for determining the elastic constant of materials as a non-destructive test. The analytical solution was based on Euler and Rayleigh beam models with simply supported boundary conditions, and the experimental work was based on Dunkerly's approach. Development of an existing test setup was done to be more suitable for beam specimens of composite materials. The present experimental measurements of the elastic constants were compared with published results and it is found that the proposed experimental work is provided acceptable and reliable measurements. The comparisons indicate errors in the measurements that are ranging between (3.1-12.7) % based on the Euler model and (0.87-4.6) % based on the Rayleigh model. Finally, a numerical solution to the problem based on the feedback of the present experimental results was developed using a computer package program called ANSYS. The numerical results reflected that the proposed experimental scheme is a simple, reliable, and accurate one.

Abstract Background Local pelvic recurrence after radical cystectomy for muscle invasive bilharzial related squamous cell carcinoma accounts for 75% of treatment failures even in organ confined tumors. Despite the proven value of lymphadenectomy, up to 60% of patients undergoing cystectomy do not have it. These factors are in favor of adjuvant radiotherapy reevaluation. objectives: to evaluate the effect of adjuvant radiotherapy on disease free survival in muscle invasive bilharzial related squamous cell carcinoma of the urinary bladder and to test the predictability of radio-sensitivity using the anti apoptotic protein Bcl-XL. Methods The study prospectively included 71 patients, (47 males, 24 females) with muscle invasive bilharzial related squamous cell carcinoma of the bladder (Stage pT2a-T3N0-N3M0) who underwent radical cystectomy in Assiut university hospitals between January 2005 and December 2006. Thirty eight patients received adjuvant radiotherapy to the pelvis in the dose of 50Gy/25 fractions/5 weeks (Group 1), while 33 patients did not receive adjuvant radiotherapy (group 2). Immunohistochemical characterization for bcl-xL expression was done. Follow up was done every 3 months for 12 to 36 months with a mean of 16 ± 10 months. All data were analyzed using SPSS version 16. Three years cumulative disease free survival was calculated and adjusted to Bcl-XL expression and side effects of the treatment were recorded. Results The disease free cumulative survival was 48% for group 1 and 29% for group 2 (log rank p value 0.03). The multivariate predictors of tumor recurrence were the positive Bcl-XL expression (odd ratio 41.1, 95% CI 8.4 - 102.3, p < 0.0001) and radiotherapy (odd ratio 0.19, 95% CI 0.05 - 0.78, p < 0.02). With Cox regression, the only independent multivariate predictor of radio-sensitivity was the Bcl-XL expression with odd ratio 4.6 and a p value < 0.0001. All patients tolerated the treatment with no life threatening or late complications during the period of follow up. Conclusions Adjuvant radiotherapy for muscle invasive bilharzial related squamous cell carcinoma of the urinary bladder has potential effectiveness and minor side effects. Moreover, Bcl-XL expression is a valuable tool for predicting those who might not respond to this adjuvant treatment.

Abstract Background In Egypt, where bilharziasis is endemic, bladder cancer is the commonest cancer in males and the 2nd in females; squamous cell carcinoma (SCC) is the commonest type found, with a peculiar mode of presentation. The aim of this study is to identify and rank the risk factors of muscle invasive bladder cancer (MIBC) in Upper Egypt and describe its specific criteria of presentation and histopathology. Methods This is an analytical, hospital based, case controlled study conducted in south Egypt cancer institute through comparing MIBC cases (n = 130) with age, sex and residence matched controls (n = 260) for the presence of risk factors of MIBC. Data was collected by personal interview using a well designed questionnaire. Patients' records were reviewed for histopathology and Radiologic findings. Results The risk factors of MIBC were positive family history [Adjusted odds ratio (AOR) = 7.7], exposure to pesticides [AOR = 6.2], bladder stones [AOR = 5], consanguinity [AOR = 3.9], recurrent cystitis [AOR = 3.1], bilharziasis [odds ratio (OR) = 5.8] and smoking [OR = 5.3]. SCC represented 67.6% of cases with burning micturition being the presenting symptom in 73.8%. Conclusion MIBC in Upper Egypt is usually of the SCC type (although its percentage is decreasing), occurs at a younger age and presents with burning micturition rather than hematuria. Unlike the common belief, positive family history, parents' consanguinity, exposure to pesticides and chronic cystitis seem to play now more important roles than bilharziasis and smoking in the development of this disease in this area.