مجید قاسمی

The energy crisis and environmental concerns in recent decades are a serious challenge to human life. The fuel cell, especially the solid oxide type, has been welcomed due to its features such as fuel flexibility, good efficiency and no need for precious metals. However, the problems of hydrogen fuel, such as the low energy density of the gas phase, difficult storage and portability, have suggested ammonia as a suitable alternative fuel. In this research, tubular all porous solid oxide fuel cell ammonia fueled has been simulated and investigated. Therefore, the equations of conservation of mass, momentum, energy, species and electric flux are defined, coupled and solved in the form of finite element code. The results show that the presence of electrolyte porosity increases the efficiency of fuel cell ammonia fueled. It was also observed that the power and current density of the fuel cell have a direct relation with the operation temperature and flow rate and an inverse relation with the porosity of the electrodes.

According to the declining trend of fossil fuel resources and the need to use renewable energies, appropriate research should be conducted for technical and functional studies in this regard. Therefore, in this research, a tubular PEM fuel  cell as a suitable energy source with three-dimensional geometry has been numerically simulated and investigated. For a comprehensive study, the equations of continuity, momentum, energy, stress-strain, and fluid-solid-heat interaction at steady state are defined, coupled together, and then solved by a finite element numerical code. Assuming the cell voltage changes from 0.95 to 0.4 volts, the passage of compressible fuel and air through the channels and porous media of the electrode and catalyst, and also about 6 degrees increase in the average cell temperature, causes approximately 35 nm displacement in different parts. These displacements, due to fluid-solid-heat interactions, cause thermal and mechanical stresses. The maximum stress is about 3500 kN/m2  in the electrolyte due to its displacement limit (average displacement 12.8 nm). Then the relation of voltage variation with current density, stress, fuel flow rate, displacement and fuel cell temperature was shown. Also the results showed that the assumption of fluid-solid-heat interaction reduces the fuel cell power density by about 3%. Finally, the effect of different parameters such as fuel and air channel radius, electronic and ionic conductivity were investigated. For example, at a voltage of 0.4 volt, 20 percent reduction in the radius of air or fuel channels, or 100 percent increase in the electron or ionic conductivity, increases the electrical current density by about 2.17, 0.05, 3.69, and 40 percent, respectively.

rapid population growth will increase the need for renewable energy resources. On the other hand, the extent of pollution from fossil fuels has made life on Earth difficult. However, the need to choose a suitable, cheap and clean alternative to fossil fuels is obvious. One of the proposed energy sources is electrical energy generated by fuel cells, which are currently a suitable solution due to high efficiency, non-pollution of the environment and the use of hydrogen as fuel. In this research, a solid oxide fuel cell with two different geometries is simulated in three dimensions. The equations governing the performance of the fuel cell, including electrochemical, momentum, mass transfer, and energy, are coupled using a finite element code defined, solved, and investigated. The results showed that the tubular geometry with the same dimensions and mechanical characteristics has a better performance than the planar type. It was shown that solving the energy equation and non-uniform temperature distribution reduces the power density of the fuel cell by about 7%. It was also found that cathodic pressure changes have a greater effect on fuel cell performance than anodic pressure changes. In the end, the results showed that increasing the thickness of the anode has a significant effect on increasing its performance compared to increasing the thickness of other fuel cell components.

Previous studies have shown that people with a family history are more likely to develop multiple sclerosis (MS). The purpose of this study was to investigate the relationship between positive familial history and disability rates based on the Extended Disability Status Scale (EDSS) among the patients with MS.

This cross-sectional study was performed on 320 patients with MS referred to MS Clinic in Kashani hospital, Isfahan, ran, who were randomly selected and divided into two groups with and without familial history. Data related to patients' demographic characteristics and data related to age of onset, number of attacks per year, and EDSS were supplemented by face-to-face interviews and examinations performed by a physician. The EDSS ranking criterion was determined based on neurological function and functional systems (cerebral, pyramidal, brainstem, etc.).

There was no significant difference between the average number of attacks per year in both groups of with or without positive family history. In addition, there was no significant difference in the mean of primary and secondary EDSS between two study groups.

Our study showed that the age of patients with familial type of MS was significantly lower than the age of patients with non-familial type. However, there was no significant difference in the degree of disability between the group of patients with or without familial history.

Cardiovascular diseases have been one of the main causes of death throughout the world in recent decades.One of the most common heart diseases is stenotic arteries, which usually appears with middle age. This disease, called atherosclerosis, causes an abnormal reduction in the inside diameter of blood vessels. In this study, the effect of a uniform magnetic field on blood flow and artery walls is investigated. The geometry of the problem is simulated in three dimensions. The governing equations, which include continuity, momentum, ohm’s law, stress-strain of linear elastic material, and fluid-solid interaction with moving mesh method, are defined, coupled, and solved with a finite element code in the Comsol software.The results indicate that the magnetic field has a significant effect on the behavior of blood flow and artery walls. For example, the Hartmann number is inversely related to the blood flow velocity and is directly related to the wall shear stress, the von Mises stress, and the artery wall displacement. It is also observed that the trend of changes with non-Newtonian viscosity model is greater than the Newtonian model.

One of the most common cardiovascular deseases is stenotic arteries. In this study, blood flow with different models of viscosity in a stenotic artery with the assumption of a wall has been investigated. Stenosis geometry is modeled by cosine relation. for The problem equations including continuity, momentum, energy, Hooke's law for linear elastic material, and the method (ALE) for fluid-solid interaction are defined and solved as finite element code. The results showed that the vessel wall had the most displacement near the stenosis region. Assuming the fluid-solid interaction reduces the wall shear stres. For example, the maximum wall shear stress in the stenotic region decreases from 2.32 to 2.23 with Carreau viscosity and from 2.1 to 2 with Newtonian viscosity. It was also observed that applying heat flux on the outer surface of the vessel wall causes a significant increase in blood flow and the wall temperature in the stenotic region.

The direct impact of bitumen properties on the performance of asphalt mixtures has made bitumen behavior modification one of the key issues for researchers. Studies in this area have shown that waste Crumb Rubber have positive and acceptable effects on classical behavior of bitumen, but the rheological behavior of bitumen has been less studied. In this study, 8, 12 and 16 percent of Waste Crumb Rubber (#80 sieve size) by the weight of bitumen were used and then SHRP tests including Rotational Viscometer (RV), Dynamic Shear Rheometer (DSR), Bending Beam Rheometer (BBR), Rolling Thin-Film Oven (RTFO) and Pressure Aging Vessel (PAV) and SHRP Plus test including Multiple Stress Creep Recovery (MSCR) were performed on the samples .finally the Performance Grade (PG) of bitumens was evaluated by standard method and also by the results of MSCR test. The results showed that with increasing CR percentage, viscosity and high temperature PG increased so that the sample containing 16 percent CR had the highest temperature grade. also aging after RTFO had no effect on high temperature of PG.Increasing the CR had a positive effect on Jnr and increased the elastic behavior and consequently the bitumen's rutting resistance, especially the specimen containing 16 percent CR achieved the H traffic level which included heavy traffic load (10 to 30 ESALs) or slow moving. It also improved the low-temperature performance of bitumen for samples containing 8 and 16 percent of CR. review of the PG map of Iran showed that bitumen containing waste Crumb rubber is usable in most parts of the country

A fuel cell is an electro-chemical tool capable of converting chemical energy into electrical energy. The high operating temperature of the solid oxide fuel cell (SOFC), (between 700oC to 1000oC), causes thermal stress which is the origin of crack initiation and propagation. Thermal stress causes gas escape, structure variability and SOFC operation cessation before its lifetime. The purpose of the current paper is to present a method that predicts the thermal stress distribution and forecasts the beginning of fissure or crack occurrences in an anisotropic porous electrode of the planar SOFC. The governing coupled non-linear differential equations of heat transfer, fluid flow, mass transfer, mass continuity, and momentum are solved numerically. A code based on computational fluid dynamics (CFD), computational structural mechanics and finite element method (FEM) is developed and utilized. The results show that the highest thermal stress occurs at the lower corners of anode and the upper corners of cathode. The cathode’s thickness at the left side increases by 1.5% and the concentrated temperature and thus the fissure occurs between the top and bottom left corners of the cathode.

For conquering the crisis of the diminution of fossil fuels resources and environmental problems owing to their excessive consumption, some alternative technologies have been introduced. Among these possible choices, the fuel cell technology is a prominent candidate for a large scale and long term energy source. Between different types of fuel cells, the Polymer Electrolyte Membrane Fuel Cell (PEMFC) attracts greatest interest for its noticeable advantages and more over for being a “Green Energy” as it simply generates electricity by combining Oxygen and Hydrogen and producing merely water. However, the most important hindrances in the way of commercializing this technology are those associated with water and heat management in PEM fuel cells. In the present work the dynamic and droplet motion mechanisms is simulated by Volume of Fluid (VOF) two phase technique and implementing of Hoffman function as hysteresis model. In this study, the dynamic contact angle of the droplet motion is considered and the dynamic motion of the droplet is investigated in an application geometry that includes the manifolds of the gas flow distributor in the PEMFC. The effect of the manifold slopes on the discharge of liquid water droplets compare to straight manifold has also been studied. By changing the geometry of the inlet and outlet manifolds, the problem created in conventional geometry, which causes the obstruction of the channel caused by liquid water, is overcome, thus improving geometry improves water management in the channels.

In recent years, research on metal oxide gas micro-sensors has been rapidly developed. These sensors are small in size, low cost in fabrication and consume little power. The purpose of the current study is to numerically investigate converge micro-channel on gas inlet temperature under the influence of thermal creeping. The governing nonlinear differential equations, mass, momentum, energy, and species, are coupled and solved by a commercial code. Since the Knudsen number is between 0.01 and 0.1, the slip boundary condition, Maxwell equation, is utilized. The result shows that flow velocity and temperature increases from the micro-channel inlet to the heat source and decreases from the heat source to the micro-channel outlet. Also as the inlet height and convergence increases, at the first flow velocity increases then decreases. This trend for temperature is reverse of the trend for flow velocity.

One of the main concerns for structures and infrastructures is to evaluate their reliability and functionality as they can suffer long-term damage due to gradual deterioration over time, or they can be imposed to natural or manmade hazards and overloading during their lifetime. Thus, Structural Health Monitoring (SHM) has been a hot research topic in order to introduce efficient methods and feasible techniques for evaluating, monitoring and improving structural reliability and life cycle management. The SHM process typically includes three stages: a) data acquisition: measurement of the structural responses using an array of sensors; b) extraction of damage-sensitive features; and c) analysis of extracted features to develop statistical models and estimate structure health condition. During the last decades, vibration-based damage detection methods have been greatly developed. The purpose of these methods is to determine the resulting changes in structural properties including stiffness, natural frequency, mode shape and damping ratio of the structure. For example, the basis of the Fourier Transform (FT) method is to determine the structural modal parameters from the random vibration data in the frequency range. Since local damages mostly impact higher frequency modes which are hard to excite and detect, most of FT based methods are unable to detect local or light damages accurately. Therefore, time-frequency analysis is introduced to overcome the limitations of the Fourier method, the most important of which is not providing a frequency-time range of a signal. The first case of frequency-time analysis was the short-time Fourier transform method based on the Fourier transform of the data divided by the time window function. According to this method, the interaction between time and frequency is difficult due to the existence of the time window function. If the windows are smaller in the time segment, its accuracy increases and in the frequency domain it becomes less accurate. The signal processing techniques such as wavelet transform and the Hilbert-Huang transform are playing an increasingly important role in structural health monitoring. Hilbert-Huang transform (HHT) is a novel signal-processing technique for analysing nonstationary and nonlinear signals. HHT method consists of empirical mode decomposition (EMD) and Hilbert transform (HT). According to this theory, the primary signals can be decomposed into different basic time-dependent intrinsic mode functions (IMFs) through the empirical mode decomposition (EMD). Afterward, instantaneous frequency and amplitude of each IMF can be obtained as Hilbert–Huang spectrum. The application of HHT based approaches in structural health monitoring has been widely studied through the numerical and experimental researches. This paper proposes a damage detection method based on the amplitude coefficient correlation of responses of damaged and undamaged structures using Hilbert–Huang transform (HHT). Structural responses have been decomposed to intrinsic mode functions (IMFs) through the empirical mode decomposition (EMD) method and the changes appear in the first IMF. Therefore, every change on the original signal can be revealed on IMFs, since the original signal depends on IMFs. Also, these changes have an effect on the analytical signal and the Hilbert transform. The instantaneous amplitude in measured joints on the structure is calculated using the Hilbert transform of the first IMF of response. The coefficient correlation matrix of the damaged and undamaged elements is demonstrated by graphical diagram in order to estimate the location of the damage. In this research, the accuracy of proposed damage detection method has been verified by applying the method on a finite element model of two-span continuous concrete beam structure. The concrete beam is 80 m long with two equal 40 m span bays covered by a concrete deck with 0.5 m thickness. The dynamic responses of the beam at all sensors have been obtained by numerical analysis of finite element model under triangular pulse loading. The responses were also contaminated with 2% random noise to consider measurement uncertainties. The damage has been modelled as stiffness reduction in a 1.25 m long segment of finite element model of beam. To evaluate the efficiency of the proposed method, different damage scenarios are studied. IMFs of all responses at sensor locations were obtained by combination of EMD and HT, and the instantaneous frequency and amplitude of Hilbert were derived. Auto correlation of instantaneous amplitude of undamaged and damaged structures were calculated and introduced as Damage Index Correlation. According to the results, this method is able to trace the location of the damage by the comparison of the correlation coefficients. Therefore, the locations of damages in different scenarios were located with a variety of coefficients correlation in sensors. The results show that the proposed method can determine the location of the damage with an acceptable accuracy for low and moderate damage intensities in all damage scenarios.

 With advances of technology and the rapid flow of global developments, universities have been located more interaction with their surrounding environment and this has created numerous challenges for higher education in various fields. Therefore, identifying them and adopting rational and realistic strategies against them will make the higher education system more effective. For this purpose, the present research, intends to identify emerging challenges in the development of higher education and provide a conceptual model in this regard.

 The present study was a type of qualitative research where using a grounded theory approach, identified emerging challenges in higher education. Data collection was carried out with a deep interviewing tool that theoretical saturation of the findings was achieved at the 16th interview. Data analysis was carried out using grounded theory method and using open, axial and selective coding. Research field in this study was experts and specialists and managers of higher education in different universities of the country. The participants were selected through a purposeful sampling (snowball type). In order to observe the qualitative characteristics of the research, three criteria of acceptability, validity and reliability were used. The outcomes of this study were presented to the university teachers participating in the study, and the results of the study were confirmed.

 According to the findings, four categories of serious and emerging challenges in higher education include: Internationalization challenges; Interdisciplinary challenges; Challenges of relation with industry; Challenges in the new fields of science were identified. If these challenges are seen from the perspective of opportunity, it will certainly provide an appropriate platform for the development of higher education. Finally, the strategies were proposed and the final model was presented.

The purpose of this study is the numerical analysis of hyperthermia on the damage of cancerous tissue in the presence of magnetic nanoparticles under the influence of external magnetic field. For this purpose the governing equations continuity, momentum, energy and arrhenius damage equation are coupled and solved by COMSOL, a finite element based code. The blood flow in capillary is assumed as non-newtonian fluid with the Carreau viscosity model. A three dimensional geometric model includes the capillary and surrounding tissue. The results indicated that the temperature of the blood stream increases with the application of the magnetic field, and the surrounding tissue is damaged over time as a result of this heat. The effect of field strength and concentration was also investigated, which was found to correlate with the amount of damaged tissue. In general, this method can be used to degrade the tissues by placing the nearby magnetic field and injecting nanoparticles at low scales.

Applying the tire rubber powder as an additive of bitumen has been one of the considerable topics for the researches. The use of the recycled tire rubber as a measure for protecting the environment moreover the considerable improvement in the bitumen performance and cheaper than the other polymers make the topic more important. In this research, in addition to the tire rubber powder, it has been tried to use the asphalt recycled from reclaimed asphalt pavement as an alternative for replacing bitumen. So, a sample of rubber modified bitumen was prepared and combined with different percentages of the recycled asphalt and tested. The aim of the tests has been examining the rutting and fatigue performance of the bituminous binder by the newer methods such as multiple stress creep recovery, temperature and frequency sweep and linear amplitude sweep. The test results showed that adding 15 to 25 percent of the recycled asphalt to the base rubber bitumen has a considerable effect in increasing complex shear modulus and decreasing the phase angle. So, the recycled asphalt improved the elastic behavior of the rubber bitumen and increased rutting resistance of the bitumen. But, the fatigue resistance of the rubber bitumen was decreased.

Caffeine is one of most important ligand of adenosine deaminase (ADA). In the present study, changes in adenosine deaminase activity were measured in Tris-HCl buffer 50mM, pH 7.3 at 37oC in the presence and absence of caffeine in increasing concentrations of adenosine as a substrate (0-50µM) and in various incubation times with caffeine. Regarding the analysis of the saturation curves, for the first time, their sigmoidal shape shows considerable differences with previous reports which can be referred to differences in concentration range of substrate and incubation time with caffeine. Based on the sigmoidal shape of saturation curve, mechanism of caffeine effect is explainable.  Moreover, based on finding of this study, the effect of caffeine on ADA activity is a function of incubation time and will be stable after 6 hours incubation of enzyme with caffeine. This is noteworthy when interpreting the results of the studies on ADA and its ligands.

The formation and expansion of the activities of the well-known institutes to the production of articles and thesis have put Iran's higher education system at faced with questions and serious challenges that has been consequences at individual, organizational and social levels. The Present study aimed to analyze intra-organizational factors in the tendency to use the articles and thesis production institutions. The study was conducted using a qualitative method and phenomenological approach. Sampling was done purposefully and with using criterion sampling. The sample size to the theoretical saturation of data was dependent that based on this, the lived experience of 22 experts in the realm of the subject was deeply investigated. The data are collected via semi-structured interviews, and was analyzed using Colaizzi strategy. Data analysis has led to the identification and categorization of five categories of effective intera-organization factors in the tendency to use the articles and thesis production institutions, including management, cultural, regulatory, educational and individual factors. The results show that developing essay writing institutions, can accompany the vitality and dynamism of scientific and academic centers with serious challenges from their inside and could be faced them with double problems in fulfilling their mission for the creating value and welfare and preparing sustainable development of society.

The purpose of this study is to numerically investigate the heat and mass transfer of magnetic nanoparticles inside a 3D capillary with non-Newtonian blood flow, Under the influence of external non-uniform magnetic field. For this purpose, the governing equations including continuity, momentum, energy, Maxwell, and concentration were coupled and solved by COMSOL, a finite element based software. Blood is assumed as non-Newtonian fluid with Carreau viscosity model and the vessel wall is assumed to be rigid. the results indicate that the concentration of magnetic nanoparticles in the upper wall of the vessel at long times reaches a constant value. This accumulation affects the blood flow temperature. Magnetic field strength, magnetic susceptibility, and concentration of nanoparticles are directly related to the temperature of the bloodstream at the location of particles accumulation. By increasing the size of nanoparticles and inlet velocity, the blood flow temperature decreases so that in sizes above 70 nm, the thermal effect of particles becomes very low. Also, the non-Newtonian blood assumption has significant effect on the results.

Migraine is a common disease with throbbing and unilateral quality, which is accompanied by aura symptoms such as nausea, vomiting and photophobia. The level of procalcitonin is increased in migraine, which is due to the inflammation caused by a low level of serum serotonin. This study aims to investigate the level of serum procalcitonin in patient with migraine by prescribing serotonin agonist drugs. In this case-control study, 40 migraine patients in the center of migraine patients of al-zahra university hospital in Isfahan were selected, among which 26 patients received serotonin as a treatment while the other 14 ones were treated by drugs other than sumatriptan agonist. Then, the level of procalcitonin in these patients was calculated and analyzed. Findings: The results of the study showed that there was a difference between of the case and control groups in the level of procalcitonin in the serum of their sample blood tests. It seems that the case group patients have a lower level of procalcitonin compared to the control group. Totally, the current study indicates the effect of serotonin in reducing the level of serum procalcitonin.

The main aim of this research was to identify effective components on policymaking based on the market-place in Iran's higher education. The research methodology was qualitative and Grounded Theory, and the data gathering tool was a semi-structured interview. The sampling method was purposive and 40 researchers and specialists of  technology, research and sciences ministry and universities of Hamedan, Kurdistan, and Sistan and Baluchestan provinces were selected for interviews. The data was analyzed by using themes analysis in the forms of Open, Axial and Selective coding. Policymaking based on market-place in higher education at two dimensions of horizontal and vertical was the central hypothesis of the research. The vertical policymaking based on market-place includes: labor culture-making, modifying the structure of universities and market, need-assessment based on market- place, modifying educational roles (educational, research, faculty) based on market-place, government supporting of internal knowledge-producing and productions, advertising of universities' ideas regarding market- place, macro and micro policy making regarding market-place. The horizontal policymaking based on market-place includes: changing the curricula based on economical approaches, relationship between industry and university, training entrepreneurship students in market-place, policies of training and learning skills, using information technologies in market-place and universities, considering educational issues based on economy, turning Human resources to Human Capital, changing evaluation system. At last, the policymaking based on market-place model was presented by using the research findings.