Optimization of furnace residence time and ingots positioning during the heat treatment process of large size forged ingots

High-strength large size forgings which are widely used in the energy and transportation industries (e.g., turbine shaft, landing gears etc.) acquire significant mechanical properties (e.g., hardness) through a sequence of heat treatment processes, called Quench and Temper (Q&T). The heating process (tempering) that takes place inside gas-fired furnaces has a direct impact on the final properties of the product due to several major microstructural changes taking place at this step. Therefore, material properties are usually optimized by controlling the tempering process parameters such as time and temperature. A non-uniform temperature distribution around parts, as a result of thermal interactions inside the furnace or loading pattern, may result in the parts property variations from one end to another, changes in microstructure or even cracking. On the other hand, improvement of large products residence time inside the heat treatment furnace can minimize energy consumption and avoid undesirable microstructural changes. However, at the present time, the industrial production is mainly based on available empirical correlations which are costly and not always reliable. Accurate time-dependent temperature prediction of the large size forgings within gas-fired heat treatment furnaces requires a comprehensive quantitative examination of the heating process and an in-depth understanding of complex conjugate thermal interactions inside the furnace. Limitations in analytical studies and complexity and cost of experimentations have made numerical simulations such as computational fluid dynamics (CFD), effective methods in this field of study. However, among the rarely found studies on gas-fired furnaces, smallscale furnaces or those with shorter operation times were mainly considered (using different simplifications like steady-state calculations) because of complexity of the phenomena and large calculation times. Subsequently, there are very few studies on the improvement of the loading patterns of large-size steel parts inside the gas-fired furnaces and their relevant residence time optimization. Moreover, the limitation and strength of different numerical approaches to calculate thermal interactions in the turbulent reactive flow of the large size gas-fired batch type furnaces were addressed by few researchers in the literature. In this regard, the main objective of the present thesis is to provide a comprehensive quantitative analysis of transient heating and an understanding of thermal interactions inside the furnace so as to optimize the residence time and temperature uniformity of large size products during the heat treatment process. To attain this objective, the following milestones are pursued. The first part of this study provides a comprehensive unsteady analysis of large size forgings heating characteristics in a gas-fired heat treatment furnace employing experimentally measured temperatures and CFD simulations. A three-dimensional CFD model of the gasfired furnace, including heat treating chamber and high momentum natural gas burners, was generated. The interactions between heat and fluid flow consisting of turbulence, combustion and radiation were simultaneously considered using the k -ε , EDM and DO models, respectively. The applicability of S2S radiation model to quantify the effect of participating medium and radiation view factor in the radiation heat transfer was also assessed. Temperature measurements at several locations of an instrumented large size forged block and within the heating chamber of the furnace were performed for experimental analysis of the heating process and validation of the CFD model. Good agreement with a maximum deviation of about 7% was obtained between the numerical predictions and the experimental measurements. The results showed that despite the temperature uniformity of the unloaded furnace, each surface of the product experienced different heating rates after loading (single loading) resulting in temperature differences of up to 200 K. Analysis of the results also revealed the reliability of the S2S model and highlighted the importance of radiation view factor for the optimization purposes in this application. Findings were correlated with the geometry of the furnace, formation of vortical structures and fluid flow circulations around the workpiece. The experimental data and CFD model predictions could directly be employed for optimization of the heat treatment process of large size steel components. The second part of this study aims to determine the effect of loading pattern (in the multiple loading configurations) on the temperature distribution of large size forgings during the heat treatment process within a gas-fired furnace to attain more temperature uniformity and consequently homogenous mechanical properties. This part also focuses on the improvement of residence time of large size forged ingots within a tempering furnace proposing a novel hybrid methodology combining CFD numerical simulations and a series of experimental measurements with high-resolution dilatometer. Transient 3D CFD simulations validated by experimental temperature measurements were employed to assess the impact of loading patterns and skids on the temperature uniformity and residence time of heavy forgings within the furnace. Comprehensive transient analysis of forgings heating characteristics (including heat transfer modes analysis) at four different loading patterns allowed quantifying the impact of skids and their dimensions on the temperature distribution uniformity as well as products residence time. Results showed that temperature non-uniformities of up to 331 K persist for non-optimum conventional loading pattern. The positive influence of skids and spacers applications was approved and quantified using the developed approach. It was possible to reduce the identified non-uniformities of up to 32 % through changing the loading pattern inside the heat treatment furnace. This hybrid approach allowed to determine an optimum residence time of large size slabs improving by almost 15.5 % in comparison with the conventional non-optimized configuration. This approach was validated and it could be directly applied to the optimization of different heat treatment cycles of large size forgings. The third part of the study addresses the details of the numerical simulation of heat treatment process of large size forgings within real scale gas-fired furnaces. Specifically, assessment of chemical equilibrium non-premix combustion model for accurate temperature prediction of heavy forgings, as well as performance of six different RANS based turbulence models for predictions of turbulent phenomenon were discussed in this context. In this regard, thermal interactions at different locations of the forged block as well as critical regions such as burner area, stagnation and wake region were performed using a one-third periodic 3D model of the furnace and validated by experimental measurements. Results showed that the one-third periodic model with chemical equilibrium non-premix combustion is reliable for the thermal analysis of the heat treatment process with a maximum deviation of about 3% with respect to the experimental measurements. It was also revealed that the choice of the turbulence model has a significant effect on the prediction of combustion and heat transfer around the block. Prediction of ɛ/k ratio by different turbulence models showed a significant relation to the turbulent combustion (such as burner flame length) and block temperature predictions, around the stagnation region. Standard and realizable k - ɛ models, due to an unrealistic over prediction of turbulence kinetic energy (under-prediction of ɛ/k ratio), resulted in shorter flame length and under-prediction on the temperature of the forged block around the stagnation region; While, SST k - w model showed reasonable predictions in this region. RSM model was found as the most reliable turbulence model compared to the experimental measurements. Meanwhile, realizable k − ɛ model apart from some under-prediction on the stagnation region and flame length could effectively predict the overall temperature of the heavy forgings with reasonable accuracy with respect to the experimental data and RSM predictions

Analysis on a release history database to assist management of the software maintenance

Software maintenance is the most time consuming activity in the life cycle of software. Software maintenance suffers from missed deadlines and from being over budget. Managers usually pay more attention to development than to maintenance: for example, they prefer to assign senior developers to the development phase tasks and neglect maintenance ones. Managers have difficulty identifying problems, and their causes, in maintenance. This thesis presents techniques for analysis on the proposed release history database to provide metrics for improvement of the maintenance phase. The proposed release history database is enriched by valuable data that comes from an issue tracking system, code repository, and time entry system. The proposed release history database and the analysis of the data contained there provides metrics which allow maintainers to find risky and time consuming codes, recommending maintenance team and maintenance location and a suggestions for the future of the maintenance. Automation is also provided as a proof of concept through a prototypical tool

The effect of development of ethical leadership on organizational adaptability capacity, education and training organization- case study: ILKHCHI city of Iran

The aim of this study is to examine the impact of ethical leadership on organizational adaptability capacity, the city therefore is education. For this purpose, the factors affecting organizational adaptability in five dimensions based on the individual's orientation, organizational justice, power sharing, ethical conduct, transparency and organizational integration is defined roles. The population of the study, employees of city is therefore, the number of 1407 people, therefore Cochran sampling formula was used to calculate the sample size, the sample includes an estimated 302 people and to select a sample of the statistical population stratified random sampling method is used. The data collected, the questionnaire whose validity and reliability, the samples were analyzed. To analyze the data collected from descriptive and inferential statistical methods were used. Thus, classifying, summarizing and interpreting the data, descriptive statistics and then determine the normality of the data by the Kolmogorov-Smirnov inferential statistics to test hypotheses, and linear regression was used to determine the effect of the test. The results indicate that the hypothesis was confirmed, indicating that the components of the individual's orientation, organizational justice, power sharing, moral guidance, role clarity and organizational integration of organizational adaptability 98 percent of changes in education is explained and the city ILKHCHI it has an effect. the results show that the attention is given to ethical leadership, organizational adaptability capacity increases in education Ilkhchi city. And findings with the findings of Golparvar, colleagues, Abbas-Zadeh and Bvdaqy is consistent

Response Surface Methodological Approach toward Optimization of a RP-HPLC Method to Determine Paracetamol in Tablets

Response surface methodology (RSM) was applied to develop an RP-HPLC method in which paracetamol was analyzed and determined on a C18 column with UV detection. To explain more, RSM was used to statistically model the impact of flow rate (ml.min-1) (A), column temperature (°C) (B) and mobile phase composition (H2O: MeOH) (C)on the retention time (RT) of Paracetamol within tablets. Introduction: The major goal of this investigation was to optimize an RP-HPLC method which is simple, linear, accurate, sensitive and selective in determination of Paracetamol in solid dosage forms. Methods and Results:Three distinctive levels were dedicated to each evaluated factor.Box-Behnken experimental design including seventeen independent runs within a range of 25-50% MeOH ratio (mobile phase), 25-45 ºC and 0.7-1.3 mL. min-1 flow rate were carried out to explore the effectivefactors onRT of Paracetamol using RP-HPLC method. ANOVA results revealed that quadratic model was significant (Model F-value of 225.65) and could best describe the relationship between dependent variable (RT) and independent ones: RT= 3.30 - 1.2A - 0.38B - 0.80C + 0.30AC + 0.43BC + 0.53A2 As can be understood from the model terms, the most significant term was the solvent ratio and all the factor levels were indirectly proportional to the Rt. Moreover, the interaction of column temperature and solvent ration seemed to be more important. It was also predicted that optimum assay condition included 1:2 ratio of methanol to water, column temperature of 35ºC and mobile phase flow rate of 1.3 mL.min−1. Using this optimum condition, baseline separation of the drug was achieved with a good resolution and a run time of 2.1 min. The optimized method was validated in terms of linearity, accuracy, limit of detection and limit of quantification of paracetamol within a few commercially available Paracetamol tablets. Conclusions:The optimized RP-HPLC technique provided a convenient and efficient method toward qualitative/quantitative analysis of Paracetamol in its tablets. The improved method is also rapid and sensitive enough to be used for single tablet analysis

Antioxidant Levels in Cord Blood of Term Neonates and Its Association with Birth Weight

How to Cite This Article: Mirzarahimi M, Ahadi A, Bohlooli SH, Namakikhalajan E, Barak M. Antioxidant Levels in Cord Blood of Term Neonates and Its Association with Birth Weight. Iran J Child Neurol. Winter 2016; 10(1):31-34. AbstractObjectiveDue to excessive production of free radicals and antioxidants evolved mechanisms against oxidative stress, infants are very vulnerable. As there was a significant relation between antioxidant levels and birth weight, we aimed verify this relationship.Materials & MethodsIn this descriptive analytical study we evaluated the antioxidant status of 40 healthy term newborns (gestation age 38-42 wk) with weight >2500 g (AGA) and 40 healthy term newborns (gestation age 38-42 wk) with LBW babies (weight < 2500 g) (SGA) in Ardabil Buali Hospital, Ardabil, northwest Iran in 2014. About 15 Ml of cord blood was collected after the second stage of labor.The levels of vitamin A, E, and C, catalase, glutathione peroxidase (GPX), bilirubin and serum uric acid were measured by standard methods. Informed consent was obtained from newborn mothers and study protocol was approved by university Ethics Committee. Data were analyzed using SPSS.19.ResultsThe mean levels of bilirubin, vitamin C, E, catalase and GPX in AGA group were significantly higher than SGA group but the mean of serum uric acid in SGA group was more than AGA. In addition, the mean of vitamin A was similar in two groups.There was a significant relation between antioxidant levels and birth weight in term newborns.ConclusionIn line with other studies the amounts of antioxidant levels except serum uric acid in AGA group was significantly more than SGA group

Investigation and prioritizing the key factors of success in small and medium size enterprises, Res

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Relationships among frozen-thawed semen fertility, physical parameters, certain routine sperm characteristics and testosterone in breeding Murrah buffalo (Bubalus bubalis) bulls

Aim: The present study was carried out to examine the relationships among frozen-thawed semen fertility, physical parameters, seminal quality, and testosterone concentration in Murrah buffalo bulls. Materials and Methods: A total of 30 breeding Murrah buffalo bulls (either progeny tested or under progeny testing program) were randomly selected from two government bull farms in Punjab. None of the bulls selected for this study had any preceding physical abnormality. A field fertility trial was conducted to determine the first service conception rate (FSCR). The number of females inseminated per bull semen was 10. All the bulls were inspected for structural soundness, measurement of scrotal circumference, testicular biometry, and internal pelvic area (IPA). Frozen-thawed semen was evaluated for total motility, progressive motility, viability, concentration, abnormality, and hypo-osmotic swelling test (HOST). Testosterone was estimated in blood plasma, seminal plasma as well as frozen-thawed semen extracts for establishing relationship. Results: The FSCR was 48% in the bulls having a scrotal circumference of ≥44 cm, although, there was no significant correlation between FSCR and scrotal circumference. Similarly, no consistent relationship existed between sperm concentration and scrotal circumference. A positive correlation was observed between IPA and FSCR (r=0.294). Of the six post-thaw seminal components (total motility, progressive motility, viability, HOST (%), total abnormality and concentration) only total motility had a high significant (p<0.01) correlation with FSCR (r=0.694). Varied correlations existed between other seminal parameters and fertility. Using a simple regression analysis, the post-thaw motility, IPA, prepuce length and testosterone (independent variables) combined to explain approximately 62% of the variation in the FSCR (dependent variable). Conclusion: The present study indicated that despite low to high correlations between seminal characteristics, physical parameters, fertility, and testosterone; the observations support the importance of these components and their function in maintaining semen quality and subsequent fertility

Antioxidant Activity-Mediated Neuroprotective Effects of an Antagonist of AT1 Receptors, Candesartan, Against Cerebral Ischemia and Edema in Rats

We examined the effects of post-ischemic blockade of angiotensinAT1 receptors by candesartan on cerebral infarction and formation of edema. Male Sprague–Dawley rats were divided into three groups, sham, control ischemic, and candesartan-treated (0.3 mg/kg) ischemic. Transient focal cerebral ischemia was induced by 90-min-long occlusion of the left middle cerebral artery followed by 24-h-long reperfusion. Neurological deficit score was evaluated at the end of the reperfusion period. Thereafter, the animals were randomly selected and used for three projects: (i) Measurement of the infarct volumes, (ii) investigation of ischemic brain edema formation using a wet/dry method, and (iii) assessment of the malondialdehyde (MDA) and reduced glutathione (GSH) concentrations using a HPLC technique. Induction of cerebral ischemia in the control group produced considerable infarctions in the cortex and striatum in conjunction with severely impaired motor functions. Candesartan treatment significantly reduced the infarct volumes and improved the above functions. The water content in the left (lesioned) hemisphere was considerably elevated in the control ischemic group. Candesartan treatment significantly lowered the water content in the ischemic lesioned hemisphere, retained tissue GSH level, and led to a lower MDA production. AT1 receptor blockade by candesartan treatment can noticeably decrease ischemic brain injury and attenuate edema formation, likely via increasing the antioxidant activity.Досліджували ефекти постішемічного блокування ангіотензивних рецепторів AT1 кандесартаном щодо зони церебрального інфаркту та формування набряку. Самці щурів лінії Спрейг–Доулі були розділені на три групи (інтактних контрольних, контрольних з ішемією та ішемізованих, котрим уводили 0.3 мг/кг кандесартану). Епізод фокальної ішемії мозку створювався за допомогою 90-хвилинної оклюзії лівої середньої церебральної артерії; оклюзія супроводжувалася 24-годинною реперфузією. Неврологічний дефіцит оцінювався в балах після закінчення періоду реперфузії. Потім тварини рандомізовано відбиралися для вимірювань трьох видів: об’єму зони інфаркту, ступеня набряку мозку з використанням методу „суха/волога тканина” та концентрацій малонового діальдегіду (MDA) й відновленого глутатіону (GSH) з використанням методики HPLC. Індукція церебральної ішемії у відповідній контрольній групі призводила до розвитку значних інфарктів у корі та стріатумі, спряженому з важкими порушеннями моторних функцій. Уведення кандесартану забезпечувало істотне зменшення об’ємів інфарктів і послаблення порушень зазначених функцій. Вміст води в лівій (ураженій) півкулі в контрольній групі з ішемією був значно підвищеним. Використання кандесартану призводило до значного зменшення вмісту води в ішемізованій лівій півкулі, відновлення рівня GSH у тканині та зменшення продукції MDA. Отже, блокування AT1-рецепторів кандесартаном може помітно зменшувати ступінь ішемічного пошкодження мозку та послаблювати формування набряку; ці ефекти опосередковуються підсиленням антиоксидантної активност

Identificación y énfasis de factores efectivos de efectividad del e-learning mediante análisis jerárquico en el Ministerio de Educación iraní

The purpose of present study was to identify and prioritize the effective factors of electronic learning effectiveness in the Ministry of Education of Iran, using a hierarchical analysis and through a descriptive-survey method. The statistical population of present study included managers and experts of Education Organization and a sample of professors with Ph.D. in Educational Sciences as well as experience of teaching in electronic training. Therefore, purposeful non-random sampling method was used to select the sample size. The used tool was a hurricane-thinking questionnaire. Indicators were organized as a questionnaire in the form of 5-point Likert scale and the effective factors of electronic learning effectiveness were identified through implementing subsequent rounds. The reliability of research tool with 28 items was calculated equal to 0.88 using Cronbach’s alpha. Data analysis in the section of identifying effective factors of e-learning effectiveness was performed using Delphi method and utilizing from SPSS Software and in the section of prioritizing was performed through AHP method using Expert Choice Software.El propósito del presente estudio fue identificar y priorizar los factores efectivos de efectividad del aprendizaje electrónico en el Ministerio de Educación de Irán, utilizando un análisis jerárquico y mediante un método de encuesta descriptiva. La población estadística del presente estudio incluyó a gerentes y expertos de Organización Educativa y una muestra de profesores con Ph.D. en Ciencias de la Educación así como experiencia en la docencia en formación electrónica. Por lo tanto, se utilizó un método de muestreo intencional no aleatorio para seleccionar el tamaño de la muestra. La herramienta utilizada fue un cuestionario de pensamiento sobre huracanes. Los indicadores se organizaron como un cuestionario en forma de escala Likert de 5 puntos y los factores efectivos de la eficacia del aprendizaje electrónico se identificaron mediante la implementación de rondas posteriores. La fiabilidad de la herramienta de investigación con 28 elementos se calculó igual a 0,88 utilizando el alfa de Cronbach. El análisis de datos en la sección de identificación de factores efectivos de la efectividad del e-learning se realizó utilizando el método Delphi y utilizando el software SPSS y en la sección de priorización se realizó a través del método AHP utilizando el software Expert Choice

Reconocimiento y clasificación de la gestión del desempeño organizacional basado en un enfoque impulsado por procesos en una organización estatal

La evaluación del desempeño y la presentación de un modelo de desempeño integral siempre se han considerado como una de las preocupaciones importantes de los gerentes. La provisión de un modelo de desempeño integral a nivel de las organizaciones estatales es un tema que ha sido investigado durante muchos años. El propósito principal de este estudio es el reconocimiento y la clasificación de la gestión del desempeño organizacional con base en un enfoque impulsado por procesos en las organizaciones estatales. Este modelo se ha propuesto en tres dimensiones: individual, grupal y organizacional. Para ello, en primer lugar, se ha preocupado la identificación de componentes. Entonces, se ha utilizado la herramienta de entrevistas a expertos. En la segunda parte, se utilizaron 384 expertos de organizaciones estatales para examinar la adecuación del modelo. Los resultados del examen de la aptitud del modelo ilustraron que el modelo final tiene una aptitud estadística adecuada. Finalmente, para priorizar los componentes de la investigación se utilizó el método de jerarquía analítica y el software de elección de expertos. Los resultados mostraron que la tasa de inconsistencia en esta etapa se calculó al nivel de 0.09, lo que indica la idoneidad de la situación por pares de comparaciones. Los factores organizacionales con peso de 0.48, los factores individuales con peso de 0.3 y los factores de grupo con peso de 0.22 tienen el peso más alto y más bajo entre las dimensiones principales respectivamente