javad akbari

The conventional material removal processes have always run into difficulties in machining hard materials, and nickel-based superalloys are no exception. The inherent properties of these materials usually lead to high tool wear rates and low surface integrity. These concerns justify the need for combining conventional material removal processes with advanced technologies. Laser Assisted Machining is one such process by which, through localized softening of work material prior to the cutting operation, a more efficient material removal process can be realized compared with what can be done by conventional machining. This work studies the effect of machining parameters such as constant Rotational speed at 400 RPM, feed rates of 0.035, 0.07, 0.105 mm/rev, and cutting depths of 0.3, 0.6, and 0.9 mm on variation of cutting force, chip temperature, surface roughness, and microhardness in variation of the workpiece surface. The process is a Laser Assisted Turning (LAT) process compared to conventional Turning (CT) by analyzing the parameters for a Waspaloy. A fiber laser with constant power output of 500 W was used to irradiate the tool material. The angle of contact of the beam with the tip of the tool was fixed at 60°. The workpiece's hardness was 385 ± 10 Vickers initially and had a diameter of 25 mm. It has been revealed that the application of LAT decreases the cutting force up to 16% compared to CT. The workpiece surfaces produced by LAT had higher chip temperatures than CT and were of 42% better quality in terms of surface roughness. In the LAT process, the difference in microhardness values at different points on the workpiece surface was within a much smaller range than in the CT process. The results showed that as the scanning speed of the laser increased on the surface of the workpiece, the thickness of the laser heat-affected zone below the surface of the workpiece decreased.

Waspaloy is a type of nickel-based superalloy that is mainly used in aircraft turbine parts, compressor disks, shafts, and turbine parts. Waspaloy, like many nickel base superalloys, is difficult to machine at room temperature (conventional turning). In this paper, the cutting and feeding forces and cutting temperature have been evaluated by changing rotational speed, feed rate and constant depth of cut, in the dry oblique turning process of Waspaloy. The workpiece's diameter and hardness were 25 mm and 385±10 Vickers, respectively. In order to investigate of the cutting force, temperature and the surface roughness, a full factorial design experiment was used, and a regression model of the influencing factors was presented. Moreover, the surfaces roughness and micro hardness of the machined parts were evaluated. The results showed that the hardness on the surface of the workpiece increases with the increase of the cutting depth and the feed rate.

Virtual learning has been defined as any system of education and instruction that brings together participants who are separated by geographical distances or time. Significantly, in a virtual learning environment, interactive telecommunications systems are utilized to connect learners, resources, and instructors. As such, the present study sought to investigate the possible effect of a synchronous virtual learning environment on the reading comprehension of undergraduate EFL university students. To this end, from the population of students majoring in English translation at Islamic Azad University, Isfahan, Iran, one control group, and one experimental group were non-probabilistically selected based on their availability. Indeed, thirty students were chosen for the control group and thirty students were nominated for the experimental group. Live interactive teaching rooms were utilized in the experimental group during the term, whereas asynchronous instructional practices were adopted in the control group within the study. According to the results of paired samples t-test, the experimental group, which was instructed by live interactive teaching rooms over the term, progressed at the end of the period as compared to the beginning of the term. Moreover, the independent samples t-test showed that the students' scores on the post-test in the experimental group were higher than that of the control group. Evidently, the results of the present study may have practical implications for EFL teachers, online instructors, distance education programmers, materials developers, and syllabus designers.

Today's man is not able to live without considering what has happened to him, and in order to have a better life, he must rely on the infrastructure he has already acquired. Human identity is manifested in the most basic state in the environment that is self-decorated. With the arrival of cultural elements from other countries, especially western countries, the culture and the identity of the Iranian society have undergone changes; Therefore, today, the discussion about identity and culture has been paid attention to in various scientific branches. Since one of the methods of investigating the identity of society is to pay attention to its spatial and urban communication elements, this article is presented with the aim of investigating the place of mosque architecture in giving identity to the urban space. The goals of this research are to revive the urban space and its aesthetic features, to breathe a new spirit in different social, economic, cultural and physical fields, to change the level of culture, to preserve and promote ancient values, to create a contemporary urban space with the pattern of elements Tradition and consolidation of the sense of belonging to the named place.

The research method in the data collection section was carried out in a qualitative manner, the extraction and examination of the elements of identity in the architecture of mosques was carried out in the form of a conceptual diagram and in a library and documentary manner.

The findings of the research show that paying attention to the body and the way of arranging spaces and other urban elements, along with the cultural and spiritual issues that are the duties of urban designers, are among the things that promote the identity of mosques in the urban space.

Increased competition in a volatile, turbulent and volatile global marketplace has led companies to move to distant markets around the world to maintain their profitability and growth by gaining market share and earning revenue. Therefore, market orientation in modern marketing sciences has long been considered by academics and professional managers. One of the important issues of market orientation is "customer satisfaction and service quality". Therefore, the present study was conducted with the aim of the effect of market orientation on service quality and customer (student) satisfaction. The present study is descriptive-correlational in terms of applied purpose and in terms of data collection method. The method of data collection is the use of library studies and Internet searches. The statistical population of the study is the students of universities located in Ilam city. The statistical population is 23948 people and the sample size was 378 people using Morgan table. The method of simple random sampling is provided to students through telegram groups. Data collection tools of this study are market orientation questionnaires (Lee et al., 2015) and service quality (Parason et al., 2008) and customer satisfaction (Darzi and Bahat, 2018). The data of this study were analyzed using SPSS and pls3 software. The results of this study showed that market orientation has a positive and significant effect on service quality and student satisfaction and only the hypothesis of the effect of customer orientation on student satisfaction has been rejected

In this paper, an attempt has been made to provide a numerical method for investigating the mechanical properties of multilayer scaffolding. These scaffolds can be used as implants in bone fractures. For this purpose two numerical simulation methods are introduced to predict the elastic properties of multilayer cell scaffolds. These simulations are based on two models: a 3D model with a volumetric element, and a 1D model with a linear element. To compare the results of these models, three types of two- and three-layer titanium alloy scaffolds have been simulated by the two methods. Also, Young's modulus of the scaffolds has been compared with the experimental conclusions of earlier studies. The results confirm that simulations with 1D models are more cost-effective compared to 3D ones. Additionally, because of the more reliable agreement of Young's modulus results of numerical modeling with the linear element (1.8 to 5 times) compared to the volumetric element (11 to 23 times) compared to the experimental findings, the numerical method with the linear elements can be a reliable tool for studying multilayer scaffoldings.

Advances in the additive manufacturing technology have led to the production of complex microstructures with unprecedented accuracy and due todesigning an effective implant is a major scientific challenge in bone tissue regeneration and bone growth. In this research, titanium alloy cylindrical scaffolds with three-dimensional architectures have been simulated and compared for curing partial bone deficiencies. The cylindrical networks in the scaffold (outer diameter 15 and length 30 millimeters) were designed in 36 different convergent, two-layer and three-layer types with 50% and 70% porosity. In all the samples, outer layers were denser than the inner layers. Mechanical characteristics of these scaffolds have been determined by simulating uniform compression load. The stress-strain curve of the samples showed that Young’s modulus and yield stress in the scaffolds with constant porosity were related to a unit-cell and the two-layer scaffolds, without changing Young’s modulus, had higher yield stress. This advantage was more significant in high-density scaffolds.

The static deflection of the machine tool and thus the displacement of the tool due to the high machining forces is the most important factor in reducing the dimensional accuracy of the workpiece. Also, the overlap of the frequency range of operation with the machine natural frequencies causes an undesirable resonance phenomenon. Reducing the strain energy of the column and thus reducing the displacement of the tooltip, and increasing the first natural frequency of the milling machine, given that the frequency range of operating is below the first natural frequency, is a desirable change that can be achieved by optimizing the distribution of the wall thickness of the column and the arrangement of the internal rib stiffeners. In this paper, a method based on sensitivity analysis was presented to optimize the arrangement of rib stiffeners connected to plate and shell structures. In each step of optimization, by establishing a loop of relationship between MATLAB and ABAQUS software and based on the sensitivity analysis performed by the finite element solver, the stiffeners that have the greatest impact in optimizing the objective function are added to the design space. After optimizing the distribution of the wall thickness of the column using the ABAQUS software size optimization module, the method presented in this paper was used to optimize the arrangement of internal rib stiffeners. Ultimately, despite a 0.5% reduction in the weight of the column, the maximum displacement of the machine tool decreased by 6.9% and the first natural frequency increased by 16.5%.

Not only have recent global challenges including drought, climate change, land degradation and land use change impacted the quantity of available surface water and groundwater, but also water quality has been affected as well. To study this impact, Landsat 5 satellite images and water quality data were obtained to compare the effects of land use changes on surface water quality between July of 1992 and 2011. The maximum likelihood algorithm was used for preparing and processing land use maps in ENVI 4.8 and Arc GIS9.3. For land use classification, the Jeffreys–Matusita, Kappa coefficient, and overall accuracy indexes were used. The results showed that the values ​​of Kappa coefficients and overall accuracy were 84.23 and 87.72% for 1992 and 93.84% and 95.55% for 2011, respectively. Most land use changes were related to dryland agriculture and residential land use, which increased 1.46 and 2.45 times, respectively. The results for water quality parameters showed that electrical conductivity (EC) and total dissolved solids (TDS) increased during the study period and that their values ​​at Gardeh Yaghub station (basin outlet) were higher relative to the Cotter station (upstream). This observation can be explained by the fact that the Mahabad River flows through agricultural lands between Cotter and Gardeh Yaghub stations. It can be concluded that land use changes have played a major role in changing surface water quality parameters in the region and have reduced water quality of the Mahabad River during the period from 1992 to 2011.

Thermal expansion and hot deformation are two phenomena causing dimensional errors in investment casting. This error occurs in dimensions between the die and wax pattern. Therefore, the wax's thermo-physical and thermo-mechanical properties, the metal die features, and the process parameters affect the dimensions of the wax pattern. Some important effective process parameters are the injection temperature, die temperature, and holding time. In this paper, the effect of injection parameters on the dimensional accuracy of the wax model created by a metallic die is studied. The Taguchi formulation based on the design of experiments is applied to obtain the optimum condition in achieving the best dimensional accuracy. The studied specimen has an “F” shape with 10 dimensions. The root mean square (RMS) of dimensional differences is considered for accuracy analysis. The results show that if the injection temperature, injection pressure, and holding time are considered as 80oC, 20 bar, and 2.5 min, respectively, the best accuracy may be achieved.

Chronic renal failure is caused by irreversible damage to the nephrons, in which the body fails to maintain water balance and electrolytes, thereby resulting in the incidence of uremia. Various oral manifestations are associated with renal failure and can have a significant effect on the quality of life in these people. Identification and evaluation of the prevalence of these oral manifestations in patients with renal insufficiency can facilitate the implementation of appropriate interventions targeted toward the elimination of such manifestations in this group of patients. Therefore, the present study aimed to evaluate the prevalence of oral manifestations in end stage renal disease (ESRD) patients. Materials &

In this cross-sectional study, 120 ESRD patients that were under hemodialysis in Imam Reza Hospital in Kermanshah, Iran, were evaluated. Oral manifestations were recorded after the examination of the oral cavity.

In this study, out of 120 patients, 74 (61.7%) cases were male, and 46 (38.3%) cases were female. The most common underlying causes of renal failure were hypertension (35.8%) and diabetes (24.2%). The most common oral manifestations were dry mouth (66.7%), uremic odor (45.8%), white tongue (37.5%), and petechial/purpura/ecchymosis (35%). Aging was associated with dry mouth. Furthermore, diabetes showed a statistically significant relationship with dry mouth (P=0.04), taste changes (P=0.007), and petechia, purpura and ecchymosis (P=0.022).

Renal failure leads to a variety of manifestations in oral cavity. With regard to the various oral manifestations, conditions inherent to the disease, as well as the side effects of their medications and treatments, these patients need careful evaluation, oral care, and special considerations during dental treatment.

One of the most important last century challenges in the world was drought and monitoring and assessing drought severity and duration to combat and mitigate its impacts is very necessary. In recent decades, with developing of remote sensing issues, satellite-based estimating drought with high spatial resolution and different time steps were widely used. Hence, the aim of this study was focused on the analyzing drought and error distribution of TRMM satellite data-based estimation with ground data over the period 1998 to 2014. In this regard, in order to assess the accuracy of meteorological drought index based on the TRMM satellite data, 41 synoptic stations were used in Iran. In this study, error assessment criteria were included NSE, RMSE, ME, Bias and correlation coefficient and also the IDW interpolation method in ArcGIS 10.3 was used for spatial analysis. Results of drought index showed that in terms of severity, Kerman, Bushehr, Kashmar, Ghazvin, Bojnurd, Kashan stations have suffered from at least one extreme status for 1998 to 2014 and in terms of frequency, the most frequent drought was in Karaj station. Results of spatial analysis of error criteria  showed that the drought index estimated of TRMM satellite had the lower error in northeast of Iran (around Mashhad and Kashmar stations) and southwest of Iran (around Shahrkord, Esfahan, Yasouj, and Shiraz stations) while the most error was in central region of Iran (around Biarjomand, Tabass stations), respectively. In most areas of the country, drought index estimated by TRMM data had acceptable agreement with ground stations data. Calibrating the TRMM data with ground stations can be used for drought monitoring in areas without stations for networks 0.25*0.25 latitude and longitude degrees.

Porous materials are a special class of engineering materials which have received increasing interest for technical and medicinal applications within the last decade. However, one of the main challenges in the cutting of porous structure is the microfractures occurred around pores having a profound impact on the final surface quality. In this study, the effect of tool geometry on the magnitude of microfractures around pores of porous silicon has been investigated. The results reveal that as rake angle decreases, microfractures around pore edges increase influencing the cutting pressure. The calculated pressure in the contact area shows a decrease as the rake angle decreases. Increase in microfractures can be explained based on a large tensile stress area formed beneath the tool cutting edge as tool tip feeds toward pore. The simulation results agree well with the experimental results. The findings also reveal that by choosing the optimal tool rake angle in the cutting process, a nanometric surface flatness (25 nanometer) can be achieved on porous silicon.n.

Identifying the factors associated with the job prospect of their promotion can be an effective step on the academic motivation and progress of the students. Since spiritual health is an important aspect of health that strengthens the mental function and adaptability of the individual and promotes general health, this study aimed to investigate the relationship between spiritual health and the job prospect of the students of Gonabad University of Medical Sciences in 2017. This cross-sectional study was conducted on 288 students of Gonabad University of Medical Sciences. Data were collected based on a researcher-made questionnaire on job prospect hope and standard spiritual health instrument. Finally, data were analyzed by SPSS software version 16 using descriptive statistics (mean, standard deviation, frequency and percent) and analytical statistics (Linear Regression, Pearson correlation coefficient, t independent and one way ANOVA). Results were considered significant at a level less than 0.05. The mean and standard deviation of spiritual health was 90.36 ± 15.83 and the hope of job prospect was 76.05 ± 10.48. The findings of this study showed that there was a statistically significant positive correlation between spiritual health and hope for job prospect (P < 0.001). There was a significant relationship between the two dimensions of spiritual well-being (spiritual well-being and spiritual religious wellbeing) with the hope of a career future (P < 0.001). Findings emphasize the importance of addressing the issue of spiritual health among students. As spiritual health increases the hope of the job prospect of students, itis suggested that administrators should pay special attention to the students' spiritual health and the solutions to improve it.

The power of praise in changing student behavior is that it both indicates teacher approval and informs the student about how the praised academic performance or behavior conforms to teacher expectations. Notably, praise plays a significant role in the rate and success of learning process in general, and in language learning classroom in particular. Accordingly, the present study sought to investigate the significant influence of praise on the growing trend of university students with different majors, namely, TEFL and linguistics. To this end, from the population of students majoring in English, at the Islamic Azad University, Isfahan, Iran, two classes of sophomore students were selected, each containing thirty participants. Subsequently, the experimental group was exposed to a wide variety of distinguishing instructor praise expressions throughout the entire term while the students in the control group were not praised and encouraged. The results of the t- test revealed that the group which was praised by the instructor during the term progressed substantially in comparison with the other group. Moreover, there appeared to be a positive correlation between instructor praise and learner progress. Evidently, the results of the present study may have practical implications for EFL teachers, materials developers, and syllable designers.

By increasing the level of public awareness, more recyclable and natural materials are used. The aim of this research was to fabricate natural fiber reinforced composites and to investigate the effects of fiber length (5mm and 9mm), fiber mass percent (5%, 10%, 12.5%, and 15%), and fiber surface treatment on tensile, flexural, and water absorption properties of the fabricated composite. The experiments were designed, by the Taguchi method. In this research, epoxy resin and kenaf fiber have been used. Tensile, flexural and water absorption tests were performed on the samples. The highest values were 37.67 MPa for tensile strength, 4.94 GPa for tensile modulus, 31.78 MPa for flexural strength, and 6.05 GPa for flexural modulus. The lowest percentage of water absorption was 0.3%. Alkali treatment improved tensile, flexural, and water absorption properties. The optimum of fiber mass percent was 12.5% to maximize tensile strength, tensile modulus, and flexural strength, 10%to maximize flexural modulus, and 5% to minimize water absorption. Except for the tensile modulus, the effect of fiber length on the mechanical properties of the composite is observed to be less pronounced than the other two factors. To maximize the tensile modulus, the fiber length is better to be 9 mm. In this study, the values obtained for the tensile strength and tensile modulus of the fabricated composite are more than the ones in the previous works. Finally, the strength and tensile modulus obtained experimentally were compared with the ones obtained via two micro-mechanical models, modified rule of mixture, and modified Halpin-Tsia model

The activity of speaking is conducted spontaneously and there is not much time devoted to preplanning and arranging the utterances the speaker intends to deliver. Briefly defined, gambits and routines refer to the words and phrases that facilitate the flow of conversations. As such, one way to help learners acquire oral proficiency is to teach gambits that support the social skills emphasized. The present study aimed to investigate the speaking fluency of Iranian intermediate EFL learners through conversational gambits and routines. To this end, the subjects of the present study consisted of an experimental group and a control group each containing 30 students who attended listening and speaking classes. To count the frequency of gambit tokens and identify their functions, the recorded data were analyzed utilizing Keller and Warner’s classification of conversational gambits. The results of the t-test revealed that the experimental group possessed better speaking fluency based on the occurrences of gambit categories. There was a positive correlation between the number of gambits and the scores of fluency test. Evidently, the findings of the present study may have implications for EFL teachers and syllabus designers.

Laser ablation is a novel non-mechanical wheel preparation method for optimizing the treatment costs of superabrasive tools. In this study, the thermal effects of picosecond laser radiation on vitrified and resin bond CBN superabrasive grinding wheel surfaces was analytically and experimentally investigated. The analytical approach is intended to find threshold process parameters for selective ablation of cutting grains and bond material. A picosecond Yb:YAG laser device was integrated with a cylindrical grinding machine which facilitates the treatment of grinding wheel as it is mounted on the grinding spindle. It has been shown that, the extent of material ablation is defined by the maximum surface temperature induced by the laser radiation which is in turn defined by the laser pulse energy. It is also suggested that, the depth of laser thermal effects is governed by the relative speed of the laser scanner with respect to the wheel surface.

Surface and subsurface cracks in part are induced by mechanical cutting of brittle material specially glass which decrease part's life-cycle. The goal of this research is to present a finite element model for predicting induced median cracks as the most deterministic cracks on the BK7 glass subsurface in micromachining. Bilinear Cohesive Zone Method (CZM) was used for simulation of crack and its specifications. CZM's parameters were obtained and calibrated by micro-Vickers experiment and the results were validated by micro-scratch test. Finite element model demonstrated median cracks dramatically increase from ductile-to-brittle-changing-regime point in micro-scratch. Finally, the validated finite element model facilitated the prediction of the depth of median cracks with respect to tool cutting depth in micromachining.

Image retrieval is an important research field which has received great attention in the last decades. In this paper, we present an approach for the image retrieval based on the combination of text-based and content-based features. For text-based features, keywords and for content-based features, color and texture features have been used. Query in this system contains some keywords and an input image. At first, the images are retrieved based on the input keywords. Then, visual features are extracted to retrieve ideal output images. For extraction of color features we have used color moments and for texture we have used color co-occurrence matrix. The COREL image database have been used for our experimental results. The experimental results show that the performance of the combination of both text- and content- based features is much higher than each of them which is applied separately.

This study aimed to evaluate enamel roughness after adhesive removal using different burs and an Er:YAG laser. The buccal surfaces of forty human premolars were sealed by two layers of nail varnish, except for a circular area of 3 mm in diameter on the middle third. The enamel surfaces were initially subjected to profilometry analysis and four parameters of surface irregularity (Ra, Rq, Rt and Rz) were recorded. Following bracket bonding and debonding, adhesive remnants were removed by tungsten carbide burs in low- or high- speed handpieces (group 1 and 2, respectively), an ultrafine diamond bur (group 3) or an Er:YAG laser (250 mJ, long pulse, 4 Hz) (group 4), and surface roughness parameters were measured again. Then, the buccal surfaces were polished and the third profilometry measurements were performed. The specimens that were cleaned with a low speed tungsten carbide bur showed no significant difference in surface irregularity between the different treatment stages (p>0.05). Surface roughness increased significantly after clean-up with the diamond bur and the Er:YAG laser (p<0.01). In comparison between groups, adhesive removal with tungsten carbide burs at slow- or high-speed handpieces produced the lowest, while enamel clean-up with the Er:YAG laser caused the highest values of roughness measurements (P<0.05). Under the study conditions, application of the ultrafine diamond bur or the Er:YAG laser caused irreversible enamel damage on tooth surface, and thus these methods could not be recommended for removing adhesive remnants after debonding of orthodontic brackets.

Habermas is a theorist who is active in the framework of critical theory and he has، in his intellectual life، combated against different dominations، particularly against the intellectual domination which intangibly dominates people. Among his most important goals in his methodology and philosophy was critique of scientism and positivistic attitude that were trying to spread quantitative and technological views in all facets of human life. Habermas for this purpose developed and analyzed the doctrine of «knowledge-constitutive interest». In the next period of his intellectual life، he introduced the theory of «Communicative rationality» to make transparent his philosophy، and thereby to give emphasis on the efficiency of reason in the mutual understanding pattern. Habermas renewed his previous ideas، such as his theory of truth، to overcome criticisms against him. The aforementioned points are discussed in this article along with his important epistemological and philosophical views.

Many researches have been conducted to evaluate the treatment methods of borderline personality disorder (BPD). In this study we compared the cognitive behavioral therapy, pharmacotherapy and their combination. In this clinical trial, 40 males with BPD were divided randomly to four groups.(method and materials) This study is a experimental research. the sample was consider of 40 male in prison mashhad, the sample were allocted either to a experimental group or to a (control group) in a randomized design. The Beck Anexiety inventory and impulsivity checkList were used as the pre-test. Using for group pharmacotherapy (lithium carbonate, Fluoxetine).At first, all patients were evaluated by Beck anxiety test and impulsivity questionnaire. The first group received pharmacotherapy (lithium carbonate and fluoxetine). The second group received cognitive behavioral therapy including 16 sessions of 90 minutes. The third group received a combined therapy and the control group received no intervention. The same tests were administered of four groups as the post-tests. To analyze the data, a one way ANOVA and Tokay test were conducted. Analysis of variance showed that symptoms of impulsivity (F=39.71, P>0.01) were significantly different in post-tests. Tokay test revealed that combined treatment and pharmacotherapy were more effective than the other methods (P>0.01). Post-test anxiety scores also showed a significant difference among the four study groups (F=5.11, P>0.06). The findings indicated that cognitive behavioral therapy was more effective than the other three groups (P>0.01). Cognitive behavioral therapy can be effective in reducing anxiety and impulsivity symptoms in patients with borderline personality disorder.

Ultrasonic Assisted Drilling (USD) is new technique to drill difficult to machine materials. In this method, tool or workpiece vibrates with amplitude of few microns in addition to conventional drill bite rotation. In this experimental research, the bone was drilled both conventionally and using UAD, then the thrust was measured in two methods at feed rates of 50, 75 and 125 mm/s and 500, 710 and 1000 RPMs. The results show that USD method causes the thrust force decreases considerably in compare whit conventional drilling. The maximum temperature is less in USD at low RPMs.