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Showing 149 results for Asadi
Volume 21, Issue 1 (3-2021)
Abstract
The loading rate and specimen size are two main influential factors which control the tensile and compressive strengths of Quasi-brittle materials such as concrete, ceramic and rock. Most of the studies in the past have been focused on the size effect in the static loading situations i.e. in situations in which the effect of the loading rate and inertia can be ignored. In particular, fracture mechanics size effect have received substantial attention both with respect to the physical testing and the numerical modeling. On the other hand, combined effect of the specimen size and loading rate on the rock strength has received little attention in the literature. Understanding the dynamic size effect of Quasi-brittle materials such as rock is essential for better analysis and design of rock structures. This is particularly the case when rock is subjected to the blasting loads or when it is prone to the strain bursting. Studies on the failure of rock under the coupled effect of specimen size and loading rate are far from sufficient. Due to the limitations of the laboratory test devices, limited research efforts have been conducted on the size effect of materials under dynamic loading. In this study, a 3D hybrid finite-discrete element code called CA3 was used to simulate the Split Hopkinson Pressure Bar test. The Incident and Transmitted bars were modeled by the finite element method while the Brazilian specimen was simulated using a Bonded Particle Model (BPM). The bars were assumed to beave elastically while the simulated specimen could develop micro and macro cracks which eventually could end up to complete disintegration and failure. Brazilian specimens with different sizes were numerically modeled. The specimen contained a vertical notch so that fracture mechanics size effect under high strain loading rate could be studied. The samples were subjected to different loading rate by adjusting the incoming wave in the incident bar. A micromechanical model in which the contact bond strength was allowed to vary in proportion to the relative velocity at the contact point of the involved particles was employed to capture the loading rate effect. The effect of sample size on the dynamic tensile strength of rock was explored and compared with the static size effect. The results were analyzed and discussed using the dimensional analysis approach. The numerical results suggest that the dynamic size effect on tensile strength of rock is different from the static size effect. While for small loading rates, the rock strength reduces as the specimen size increases, this is not the case when high loading rates are involved. For high loading rates, with the increase in the specimen size, the tensile strength initially increases. However, with further increase in the specimen size and the increase in the distance between the notch tips and the impact points, it appears that the inertia and loading rate effects reach to a stable situation, i.e. with further increase in the specimen size, the material strength remains constant. This interesting observation is discussed and compared with the published data in the literature.
Volume 21, Issue 2 (Summer 2017)
Abstract
Today in legal system of some countries including Germany, constitutional rights (fundamental rights) affect contract law greatly. So content of contracts and rules of contract law should not contradict with constitutional rights. Right to life, freedom of speech, equality and freedom of labour are examples of the most important constitutional rights.
In legal system of these countries, effect of constitutional rights in contract law accomplishes through various methods. In accordance with direct horizontal effect method a claim or defense rises directly on the base of constitutional rights against the other party. In indirect horizontal effect although a claim or defense is on the base of rules of contract law but these rules interpret in light of constitutional rights. This manner divides to strong indirect horizontal effect and weak indirect horizontal effect. Apart from direct and indirect horizontal effect, according to a different method, constitutional rights address state, and state obliged to protect constitutional rights. This method called State duties to protect constitutional rights.
Also in Iranian legal system, constitutional rights affect contract law. So persons can not devest their constitutional rights by contracts.
In a summary of what has been proposed in this paper it can be said in Iranian contract law system, manner of effect of constitutional rights is strong indirect horizontal effect.
Volume 21, Issue 5 (11-2021)
Abstract
Considering the goals of sustainable development and increasing environmental pollution, attention to the environmental effects of each product has increased more than ever. In the meantime, the building industry plays a major role in environmental pollution, as a major part of the urban waste comes from the industry. The most important factor affecting the amount and nature of environmental impacts is the type of building system. Life cycle analysis is a method used to assess environmental impacts along with all stages of the life of a product from cradle to grave. It is a method for designing sustainable structures, identifying environmental impacts of materials throughout the life cycle, providing financial and environmental details for choosing between different options by the relevant user, and the ability to select different indicators for assessing the life cycle of the application. In this research, a framework for evaluating the environmental life cycle of buildings is described. Due to the fact that in most buildings in Iran there are steel or concrete frames, the environmental impacts of two types of steel and concrete buildings in Isfahan have been estimated and compared. The analysis of the life-cycle analysis is carried out in four stages of the production and processing of materials, materials, construction, operation and end-of-life. Environmental impacts are categorized in the form of potential warming groups, acidification potential, water nutrition, reduction of fossil fuel resources, air pollutants, human health, photochemical smoke formation potential, ozone depletion and toxic emissions. . The analysis of effects is performed during the steps of classification, determination of the coefficient of influence and normalization and weighing. This analysis is performed in steps of classification, determination of the coefficient of influence and normalization and weighting. In the stage of classification of resources or contaminants that are similar in terms of environmental effects, Commitment and the determination of a single index for the effects defined in the groups through the process of determining the coefficient of influence of each work belonging to a group, normalization (converted to a comparable and comparable scale), and ultimately weighing the effect based on the importance of the type of effect is obtained. Weighing in these methods is performed as a triangle of weighting Showed that the highest pollution was related to the production of materials and in particular the manufacture of steel. The percentage of the raw materials used was generally more than 95%. Steel structures have been contaminated with most of the environmental impacts, including global warming, suspended particles, acidification, nutrition, and smog emissions. The impact of concrete building on greenhouse gas and particulate emissions is much higher and contributes significantly to the production of steel in the production of cancerous and toxic substances. It also showed that due to the increased importance of the release of carcinogens and toxic substances in The whole effect is more and more severe on human health and environmental degradation, and the greater role of steel in the release of these contaminations, the environmental contamination of the steel structure for the release of toxic carcinogens and toxic chemicals such as chromium multiplicity, is much greater than the concrete structure.
Volume 21, Issue 149 (July 2024)
Abstract
Russian olive is one of plants belonging to the Elaeagnacea family. The aim of this study was investigating the diversity of fatty acids in seeds of some populations of Russian olive. Soxhlet apparatus was used to extract oil and chromatography was used to identify the compounds of fatty acids. The lowest and highest percentage of oil was seen in the populations of Shahrekord, Naein 1 and Semirom, respectively. The observed saturated fatty acids were myristic, palmitic, stearic, arachidonic, behenic and lignoceric acid. The highest percentage of saturated fatty acids was found in the population of Shahrekord (31.32±0.2) and the lowest percentage was seen in the sample of Semirom (2.70±0.15) without significant differences with the samples of Mimeh, Kohiaye, Naein 1 and 2, and Zarrin-shahr. The observed unsaturated fatty acids were pentadecanoic acid, palmthiolic acid, oleic acid, linoleic acid, and linolenic acid. The population of Habibabad 1 (57.54±1.60) and Farokhshahr (55.41±1.60) have the highest percentage of monounsaturated fatty acids and Mimeh population (28.30±2.00) has the lowest percentage of monounsaturated fatty acids. Shahrekord population had the lowest percentage of polyunsaturated fatty acids. In clustering and at a distance of 25, the population of Shahrekord was separated from other populations and placed in a separate cluster. It seems that the difference between the percentages of oil has caused Shahrekord population to be placed in a separate cluster. At distance 25, the population of Shahrekord was separated from other populations and placed in a separate cluster, and at distance 5, three clusters could be separated, which can be discussed based on the diversity and composition of fatty acids. The results of this study revealed that there are noticeable variations in terms of oil percent and fatty acids composition in Russian olive in studied region which can be used in special purpose.
Volume 21, Issue 152 (October 2024)
Abstract
The aim of this research was to produce a diet beverage based on aloe vera and investigate its physicochemical, microbiological, antioxidant, and sensory properties. To achieve this goal, aloe vera gel at concentrations of 5%, 5.7%, and 10% underwent heat treatment at 80°C for 30 minutes (Treatment A) and 90°C for 3 minutes (Treatment B). Aspartame was added at concentrations of 100, 150, and 200 ppm, and the beverages were stored for a period of 31 days. The study was conducted using a fractional factorial design with 34 samples under investigation. Optimization was performed based on a maximum amount of 10 gr of aloe vera, 200 ppm of aspartame, and a minimum amount of 5 gr of aloe vera and 100 ppm of aspartame. The use of the sweetener aspartame was highly effective in improving the taste of the beverage, as it provides a much sweeter sensation compared to saccharide sugars and is beneficial for diabetic patients. Based on the microbiological test results, the heat treatment (pasteurization) was successful. Furthermore, sensory evaluation showed improvements in taste, aroma, texture, and mouthfeel with the addition of aloe vera gel to the samples with no undesirable characteristics observed. After determining the models and variable combinations using the Design Expert software, an optimized sample was introduced, containing 200 ppm of aspartame, 10 gr of aloe vera, and the optimized pasteurization process, which was Treatment B for 30 minutes. The results of this study indicate that a vegetable-based diet beverage containing aloe vera can be successfully produced as a beneficial product with desirable sensory characteristics that are acceptable to consumers.
Volume 21, Issue 157 (March 2025)
Abstract
This research aimed to investigate the physical, mechanical, antioxidant, and antimicrobial properties of a smart nanocomposite film based on chitosan/ aloe vera containing hydrolyzed tomato seed protein. For this purpose, the hydrolyzed tomato seed protein was first prepared using the Alcalase enzyme under different time conditions (30, 60, 90, 120 minutes). Then, 5 edible films including nano-chitosan, nano-chitosan and aloe vera gel with different concentrations of hydrolyzed protein (0, 0.5, 1 and 1.5%) were prepared, and the film properties were evaluated. Based on the results of the hydrolyzed protein, the hydrolyzed protein had a high protein content and degree of hydrolysis. This protein also had a high content of hydrophobic amino acids (31.78%) and aromatic amino acids (11.74%). The mechanical test results of the films showed that increasing the protein concentration led to a decrease in tensile strength and an increase in elongation at break of the polylactic acid films. According to the physical test results, increasing the protein concentration did not have a significant effect on moisture and solubility, but increased water vapor permeability and turbidity (p<0.05). the hydrolyzed tomato seed protein had high DPPH radical scavenging activities and increasing the concentration had a positive effect on these parameters (p<0.05). These films also had high antimicrobial activity against pathogenic bacteria, with higher antimicrobial activity against Staphylococcus aureus than Escherichia coli. The nanocomposite film containing 1.5% hydrolyzed protein had the highest antioxidant and antimicrobial activity (p<0.05). This study showed that hydrolyzed protein can improve the physical and mechanical properties of chitosan/aloe vera based films. Specifically, films containing 1.5% hydrolyzed protein had better properties such as higher antioxidant activity and antimicrobial activity.
Masoud Asadi, Arsalan Golfam, Ferdows Aghagolzadeh,
Volume 22, Issue 1 (1-2015)
Volume 22, Issue 1 (1-2015)
Abstract
Through uncovering the underlying elements of language, this research aims to reveal the hidden layers of meaning in press texts in the framework of a critical discourse analysis. Having used socio-semantic features of Van Leeuwen's model (1996), this paper has studied, qualitatively, 40 issues of four Iranian Persian publications for a period of two months, from July 22 to September 21, 2011. These publications were 'E'temad', 'Sharq', Resalat' and Keyhan. The analyses included recognizing discursive structures in the texts, determining the linguistic realizations of structures, and explaining along with uncovering the hidden layers of meaning and the ideology behind the texts. The research results out of the data analysis indicate that the ideology dominating the minds of writers and groups is reflected in the texts using discursive features as exclusion, activation, passivation, personalization and impersonalization. Exclusion has been the most frequently used feature in 'E'temad and 'Sharq', whereas activation has had the highest frequency of occurrences in 'Resalat' and 'Keyhan'. The discursive structures take place using linguistic instruments like pre-modifiers, active vs. passive structures, coordination and circumstantials, in the texts. Besides, the relationship between discursive structures and ideology is dialectal, which can be determined by studying these structures in the texts and social institutions.
Volume 22, Issue 1 (Winter 2018)
Abstract
Aims: Nowadays, people are exposed at large quantities of magnetic field due to
Materials and Methods: The present experimental study was carried out in the employees of a power generation plant in Tehran in 2017. Using
Findings: The mean of hemoglobin concentration in the exposed group (15.67±1.42) was significantly different from that of the unexposed group (17.31±3.03), so that the hemoglobin level of the exploitation department staff was lower than that of the administrative and support staff (p<0.0001). Fourier-transform infrared spectroscopy showed significant changes in the 1413 and 11430cm-1
Conclusion: Contact with extremely low frequency of
Volume 22, Issue 2 (6-2022)
Abstract
Fine-grained soils, especially those consist of high content clay minerals, generally have high strength in dry state, but they loss their strength when subjected to absorb water as well as they may be swell. These phenomenon may lead to damage the structures located on them and it is required to stabilize them with different additive materials. Common additives for stabilization of problematic soils are cement, lime, fly ash, etc., which are almost costly and have environmental consequences. Nowadays, non-traditional material such as polymeric materials were added to the soils in order to their stabilization.
In this research, the effect of polyester polymer resin on the physical and mechanical properties of fine-grained bentonite soil, with liquid limit and plasticity index of 226% and 179% respectively, was studied by performing Atterberg limits and unconfined strength tests. For this purpose, a polyester polymer resin were added to bentonite soil with various amount of 1.0, 2.5, 5.0, and 7.5 percent in dry weight. Soil mixtures were cured about 7 days and Atterberg tests were performed on them. Moreover, cylindrical specimens with 50 mm in diameter and 100 mm in height were prepared and cured during 7, 14 and 28 days. Soil specimens compacted in a splitted steel mold at four equal thickness layers. Then, the unconfined compression tests were carried out on these specimens with loading rate of 0.5 mm/min.
The results of Atterberg tests indicated that the addition of polyester resin reduces liquid limit and increases plastic limit of bentonite and consequently it is led to decrease in plasticity index of the soil. Maximum decrements in liquid limit and plasticity index observed in treated soil with 7.5 percent polyester, which are about 41.0 and 65.0 percent respectively. In addition, the polyester resin improves the unconfined compressive strength of the soil and the rate of increment is high when the polyester amount rises from 0 to 7.5%. It was revealed that the polyester resin influences the unconfined strength considerably in a short time, and the rate of improvement gradually decreases with passing time. For example, adding 5.0 percent polyester polymer resin to bentonite soil improves the strength up to 2.05, 2.11 and 2.58 times respectively after curing times of 7, 14 and 28 days. It also means that after 7 day curing time the improvement effect of stabilizer is considerable and by passing time its effect diminishes. Moreover, adding polyester polymer resin to the soil decreases deformability of soil; it means that this additive cause the treated soil exhibits more brittle behavior rather than the pure soil. The photos of specimen after failure explain that failure surface of pure bentonite is inclined in relation with horizontal, while it tends to vertical direction in treated specimens. Analysis of SEM images, results of XRD analysis and FTIR spectroscopy suggest that polyester stabilizer penetrates into the layers of soil particles and, by inducing effective interaction makes the layers closer or sticks them together. These phenomena decrease water absorbing tendency in soil minerals and improve the plastic characteristics and shear strength of the soil.
Volume 22, Issue 5 (12-2022)
Abstract
Proper and timely maintenance of concrete pavement plays a decisive role in increasing the life of these pavements. Joint plain concrete pavement is a type of concrete pavement used for roads. One of the important parts of this type of pavement is the joints created in it. The use of joints to provide conditions for expansion and contraction in concrete pavements and thus reduce stresses due to changes in weather conditions (temperature and humidity), friction, and facilitate the manufacturing process. Due to the fact that the joint in the joint plain concrete pavements is a weakened area for the conduction of cracks from unforeseen areas of the concrete slab to it, the entry of water and other materials into it causes penetration into the underlying layers of the slab to prevent penetration. Joint Sealants are used in these areas. Hot applied bitumen sealant is one of the most common sealants used in joints, which is based on bitumen. One of the key factors in the longevity of concrete pavement is the proper functioning of the joint and joint sealant. The adhesion and cohesion failures are two main damage types in the hot-applied bituminous joint sealants in concrete pavement joints. The mentioned failures are caused by the contraction of concrete pavement under the temperature drop and fluctuation as well as vertical displacement due to passing traffic load. The failure in joint sealant causes elimination of water proofing feature in joints leading to penetration of water into the sublayers. Subsequently, the presence of water in sublayers results in pumping of water under the concrete slab, which leads to other failures types, such as faulting, blow up, corner break. The resealing of joint sealant is the commonly used approach to repair the joints, which takes considerable costs, times and environmental consequences. In recent years, induction heating has attracted substantial attentions among the pavement engineers for innovative applications, specifically for induced healing. The researchers used this method in asphalt mixtures to heal cracks and microcracks. To make the electromagnetic radiations more effective, they used bipolar additives such as activated carbon and carbon black to raise the temperature of the asphalt mixture and cover the cracks and microcracks. In this study, the induction heating and induced healing of asphalt binder was carried out in reaping the joint sealant and to recover the cohesion-adhesion failures. To this end, a new testing setup and frame were designed to conduct the tensile test on hot-applied bituminous joint sealant. First, the sealant bitumen was placed between two concrete blocks, and then the specimens were conditioned at low temperatures (i.e. -10 °C, -20 °C, and -30 °C). After conditioning, the tensile under a displacement controlled loading test was carried out until failure point of joint sealant. Subsequently, the broken joint sealants were exposed to the electromagnetic radiation in a microwave machine to heat and heal the joint sealant. Then, the tensile test was again conducted on the specimen until failure point. The results showed that induced healing can recover and heal the joint sealant experienced cohesion-adhesion under contraction loading. This observation indicates that the induced heating is a potential technique to repair the joint sealants in jointed concrete pavements.
Volume 22, Issue 10 (October 2022)
Abstract
The non-reproducibility of the measured results of a piece by reference laboratories is a problem that often causes differences of opinion in production workshops and doubts about the adjustment of production devices with the results provided by laboratories. In this paper, the effect of geometric parameters created by machining on the ability to measure control tools through statistical techniques of quality engineering is investigated, so that first a piece was subjected to drilling and machining, after measurements The exact diameter of the hole with geometric deviation was determined to be cylindrical error to 0.01 mm. Then it was examined with two common measuring systems of air gauge and coordinate measuring machine (CMM) and the capability of the instruments was calculated as follows through the mini-tab software. Capability of air gauge (Cg) in measuring the diameter of hole was 0.27 and capability of CMM device in controlling the said diameter was 0.28. After removing the scattering caused by geometric parameters to calculate the ability of measuring instruments, The power of the instruments was improved to 1.20 in the wind gauge and 1.05 in the CMM and finally, by removing or reducing the geometrical error of the work piece, the repeatability (VARIATION) and the ability of both measurement systems are improved to many times.
Volume 22, Issue 12 (December 2022)
Abstract
The concept of Zero Energy Building [5] has been introduced globally to reduce energy consumption and carbon emissions in the building sector. Renewable energy systems such as Solar Thermal collectors, Photovoltaic collectors, and Heat Pumps are used to implement ZEBs. This study proposes a Building Integrated Photovoltaic Thermal-Air Source Heat Pump (BIPVT-ASHP) to realize ZEB in a small-scale building. To evaluate the performance of the system, a BIPVT-ASHP hybrid system model was designed, and also the building load model was defined based on the actual building conditions. Then, the heating and cooling performance of the BIPVT-ASHP system was dynamically simulated for one year using TRNSYS software. Then the system was numerically evaluated from energy, economic and environmental perspectives. According to the results of this study, for this system, the initial non-renewable energy consumption was 1.29 kWh/m2 per year, which was less than the heating energy threshold for the ZEB, and the proposed system met well the ZEB conditions. In addition, it was shown that for a given area, photovoltaic/thermal technology leads to a further reduction in non-renewable primary energy consumption but less solar thermal energy production compared to traditional separate production using photovoltaic [2] collectors.
Volume 23, Issue 2 (5-2023)
Abstract
Groundwater is an essential source of fresh water, which is less prone to pollution in comparison to surface water, and access to this valuable resource is affordable. These issues make groundwater a viable source during surface water shortages such as drought, especially in arid and semi-arid countries. In this research, the equation of contamination transport in groundwater is modeled by a novel dual discrete finite volume method (DDFVM). Using this numerical method, the contamination concentrations are obtained at the center and vertices of each element. This model has been applied to an unstructured triangular mesh that could be fitted to complex geometric boundaries. For the transient flow regimes, the flow equation has been coupled with the contaminant transport problem, and the results of the numerical model are validated with the model of Modflow. Finally, the flow and transport FV coupled model has been applied in a porous media with strong heterogeneity. The free-oscillation results for the two parameters of head and concentration demonstrate the stability of the model.
Volume 23, Issue 3 (Fall 2019)
Abstract
Introduction: Disaster occurrence undermines the basis of the place and one of its consequences is the rupture of place identity and attachments, followed by a variety of psychological and social anomalies. On the other hand, the community health is linked to its sense of identity. Contradictions become apparent when this need is distorted or overlooked in the reconstruction process. Considering the profound effects of disasters on the objective and subjective landscape of the residents, and its inevitable effects on place identity and attachment, the need to create solutions aimed at rehabilitating them during the period of reconstruction and within the framework of resilience theory as the broadest approach to dealing with disasters, is seen.
Methodology: The current research has an exploratory nature so Q Methodology with a combination of qualitative and quantitative approach has been used. In the qualitative stage, the combination of the Delphi method in three stages and the grounded theory were used to codify and extract concepts and categories. The concepts that were effective on the subject of the research were used in the formulation of closed questions of questionnaires in the form of propositions with a Likert scale of 0 to 9. Panel members included 17 experts from the faculty members of three universities in Tehran, Which were initially selected using non-random sampling method, and in the next step, a non-randomized network sampling was selected. Finally, the Q factor analysis was performed on the data. Based on the findings of the grounded theory method, 6 dimensions including, emotional-cognitive, functional, physical, semantic / historical, social and cultural and 62 indicators of place identity and attachment were identified. The findings were evaluated based on the eight criteria influencing the resilient dimensions of place such as continuity, distinction, self-esteem, self-efficacy, readiness, sustainability, creativity and flexibility. After the initial pilot by 5 experts, the most relevant target - content relationship with resiliency criteria were determined. In the next level after Q factor analyzing on the data, five schools of thought were identified among the experts. Then Shannon algorithm was used to determine the process of rehabilitating resilient dimensions of place identity and attachment.
Result and Discussion: Based on the findings, the experts identified five schools of thought including place-based cognitive-emotional connections; place as the resonance of individual and collective characteristics; providing opportunities by the features and spatial affordance of place; place as the body of values and contents; and place efficiency, which rehabilitate resilient dimensions of the place identity and attachment, and as a result adaptability to Changes caused by disasters. It was also found that according to the experts' view, place identity and attachment priority order are: emotional-cognitive, physical-functional, and ultimately cultural-social dimensions.
Conclusion: it seems that place distinction along with continuity, self-efficacy and sustainability of emotional-cognitive, functional, physical, cultural, social and semantic dimensions of place, enhances self-esteem in the place, sustain dimensions of place attachment, creativity, and innovate in place belonging, and therefore resilient place identity.
Methodology: The current research has an exploratory nature so Q Methodology with a combination of qualitative and quantitative approach has been used. In the qualitative stage, the combination of the Delphi method in three stages and the grounded theory were used to codify and extract concepts and categories. The concepts that were effective on the subject of the research were used in the formulation of closed questions of questionnaires in the form of propositions with a Likert scale of 0 to 9. Panel members included 17 experts from the faculty members of three universities in Tehran, Which were initially selected using non-random sampling method, and in the next step, a non-randomized network sampling was selected. Finally, the Q factor analysis was performed on the data. Based on the findings of the grounded theory method, 6 dimensions including, emotional-cognitive, functional, physical, semantic / historical, social and cultural and 62 indicators of place identity and attachment were identified. The findings were evaluated based on the eight criteria influencing the resilient dimensions of place such as continuity, distinction, self-esteem, self-efficacy, readiness, sustainability, creativity and flexibility. After the initial pilot by 5 experts, the most relevant target - content relationship with resiliency criteria were determined. In the next level after Q factor analyzing on the data, five schools of thought were identified among the experts. Then Shannon algorithm was used to determine the process of rehabilitating resilient dimensions of place identity and attachment.
Result and Discussion: Based on the findings, the experts identified five schools of thought including place-based cognitive-emotional connections; place as the resonance of individual and collective characteristics; providing opportunities by the features and spatial affordance of place; place as the body of values and contents; and place efficiency, which rehabilitate resilient dimensions of the place identity and attachment, and as a result adaptability to Changes caused by disasters. It was also found that according to the experts' view, place identity and attachment priority order are: emotional-cognitive, physical-functional, and ultimately cultural-social dimensions.
Conclusion: it seems that place distinction along with continuity, self-efficacy and sustainability of emotional-cognitive, functional, physical, cultural, social and semantic dimensions of place, enhances self-esteem in the place, sustain dimensions of place attachment, creativity, and innovate in place belonging, and therefore resilient place identity.
Volume 23, Issue 4 (Winter 2019)
Abstract
Extended Abstract
Introduction
A large number of researches demonstrated that built environment attributes affect the walking and cycling for transportation (Ewing & Cervero, 2010; Bauman et al., 2012). Studies examining the potential effect of the built environment on physical activity have employed objective and/or perceived (self-report) measures to assess characteristics of the neighborhood environment. Findings illustrated people who live in neighborhoods with traditional or walkable designs report about 30 minutes more walking for transportation each week and more total physical activity, compared to those who live in neighborhoods with less walkable suburban designs (Frank, et al., 2006). Therefore, the association between the built environment and walking activity are complicated due to spatial heterogeneity, self-selection issues such as attitudes and perceptions on walking behavior, and methodological differences (Lee, et al., 2017). Some evidence shows that residents’ self-reports of their neighborhood environment may be less revealing than are objective assessments. However, other studies suggest that perceived neighborhood environment exerts a unique effect and may be a more telling indicator for individual health than objective neighborhood characteristics (Wen et al., 2006). So, the aim of this research is discovering the preferences of the residence towards the walkable spaces and explaining spatial association of the perceived and objective measures of neighborhood walkability in district of 4, 8 and 13 of Tehran.
Methodology
This research is a descriptive and exploratory research that has been conducted with quantitative research approach. In this regard, GIS software were used to mapping the neighborhood walkability criteria. Network analyst functions, also, was used in order to service area determination and accessibility to public services. Exploratory factor analysis and multiple regression were cooperatively employed with regard to reduce the set of variables and extract variables that explain the objective and perceived measures of neighborhoods walkability at a 95% confidence interval in Tehran metropolitan. In relation to perceived measure of neighborhoods walkability, we used the standard questionnaire developed by Saelens et al. (2002), as well as Cerin et al. (2006), has been developed as Neighborhood Environment Walkability Scale (NEWS). The questionnaire has the following dimensions: Time taken to get from residence home to the nearest businesses or facilities, Access to services, Streets condition or quality in the neighborhood, Places for walking and cycling, Neighborhood surroundings, Safety from traffic, Safety from crime neighborhood satisfaction. In the present study for each neighborhood, walkability index, which is the sum of the standard Z score of four urban form metrics, is defined as a function of net residential density (ratio of the number of residential units to residential areas in each neighborhood per hectare), sum of the ratio of floor area of retail units to their parcels in each neighborhood, Land-use mix index (entropy coefficient) and street connectivity (Number of intersections with 3 or more legs per km2). Also, census data, land use and road layers and survey data were used. The statistical population of the present study is the population of all districts of the 22 districts of Tehran. The statistical samples which selected by purposeful method were 31 neighborhoods.
Results and discussion
Findings revealed that the gap between the objective and the perceived walkability, except the component of walking and cycling places, the rest of the studied dimensions, including the time of access to shops or stores, facilities, etc., access to services; neighborhood streets; neighborhood environment; perceived security of traffic and crime; and the satisfaction of the neighborhood in relation to subjective pedestrian assessment have a higher mean in neighborhoods with high objective walkability compared to those with low walkable neighborhoods. Research findings in regard to the people preferences about the walkable spaces are in line with other studies. Residents of our case study in connection with the issue of walking, as well as people from other parts of the world, prefer spaces with appropriate access to services, facilities and infrastructure needed for everyday life, and safe, attractive, lively and free of contamination and traffic environments as well as well-defined spaces for walking. The point that needs to be mentioned is the population density, the density of residential units, as well as the density of activities (commercial and service as well as offices or administrative activities). In most previous investigations, mainly in link to walking, built environment with urban sprawl form are compared to more compact cities or so-called smart cities with mixed and diverse land uses, and the result is typically that urban environments which have a dense and smart urban form that are high in density of population, activity and residential are reported proper for walking behavior. In this regard, although the urban form of the studied neighborhoods of this research compared to many previous case studies in terms of those variables, is still more compact, according to the participants’ opinion, they prefer to walkability of their residential spaces, neighborhoods that have diverse land uses (cloth stores, food markets, supermarkets, juices and ice cream shops, home appliances malls and etc.), as well as green and open spaces and environments that have more attractive facets.
Conclusion
In order to achieve the appropriate developmental model to increase the subjective and objective walkability of urban neighborhoods, some steps must be taken to increase the green and public open spaces and redistribute the land uses in accordance with the urban smart growth pattern, by through less dependence on the personal car usage, many challenges of Tehran metropolitan will reduce in line with sustainable development.
Introduction
A large number of researches demonstrated that built environment attributes affect the walking and cycling for transportation (Ewing & Cervero, 2010; Bauman et al., 2012). Studies examining the potential effect of the built environment on physical activity have employed objective and/or perceived (self-report) measures to assess characteristics of the neighborhood environment. Findings illustrated people who live in neighborhoods with traditional or walkable designs report about 30 minutes more walking for transportation each week and more total physical activity, compared to those who live in neighborhoods with less walkable suburban designs (Frank, et al., 2006). Therefore, the association between the built environment and walking activity are complicated due to spatial heterogeneity, self-selection issues such as attitudes and perceptions on walking behavior, and methodological differences (Lee, et al., 2017). Some evidence shows that residents’ self-reports of their neighborhood environment may be less revealing than are objective assessments. However, other studies suggest that perceived neighborhood environment exerts a unique effect and may be a more telling indicator for individual health than objective neighborhood characteristics (Wen et al., 2006). So, the aim of this research is discovering the preferences of the residence towards the walkable spaces and explaining spatial association of the perceived and objective measures of neighborhood walkability in district of 4, 8 and 13 of Tehran.
Methodology
This research is a descriptive and exploratory research that has been conducted with quantitative research approach. In this regard, GIS software were used to mapping the neighborhood walkability criteria. Network analyst functions, also, was used in order to service area determination and accessibility to public services. Exploratory factor analysis and multiple regression were cooperatively employed with regard to reduce the set of variables and extract variables that explain the objective and perceived measures of neighborhoods walkability at a 95% confidence interval in Tehran metropolitan. In relation to perceived measure of neighborhoods walkability, we used the standard questionnaire developed by Saelens et al. (2002), as well as Cerin et al. (2006), has been developed as Neighborhood Environment Walkability Scale (NEWS). The questionnaire has the following dimensions: Time taken to get from residence home to the nearest businesses or facilities, Access to services, Streets condition or quality in the neighborhood, Places for walking and cycling, Neighborhood surroundings, Safety from traffic, Safety from crime neighborhood satisfaction. In the present study for each neighborhood, walkability index, which is the sum of the standard Z score of four urban form metrics, is defined as a function of net residential density (ratio of the number of residential units to residential areas in each neighborhood per hectare), sum of the ratio of floor area of retail units to their parcels in each neighborhood, Land-use mix index (entropy coefficient) and street connectivity (Number of intersections with 3 or more legs per km2). Also, census data, land use and road layers and survey data were used. The statistical population of the present study is the population of all districts of the 22 districts of Tehran. The statistical samples which selected by purposeful method were 31 neighborhoods.
Results and discussion
Findings revealed that the gap between the objective and the perceived walkability, except the component of walking and cycling places, the rest of the studied dimensions, including the time of access to shops or stores, facilities, etc., access to services; neighborhood streets; neighborhood environment; perceived security of traffic and crime; and the satisfaction of the neighborhood in relation to subjective pedestrian assessment have a higher mean in neighborhoods with high objective walkability compared to those with low walkable neighborhoods. Research findings in regard to the people preferences about the walkable spaces are in line with other studies. Residents of our case study in connection with the issue of walking, as well as people from other parts of the world, prefer spaces with appropriate access to services, facilities and infrastructure needed for everyday life, and safe, attractive, lively and free of contamination and traffic environments as well as well-defined spaces for walking. The point that needs to be mentioned is the population density, the density of residential units, as well as the density of activities (commercial and service as well as offices or administrative activities). In most previous investigations, mainly in link to walking, built environment with urban sprawl form are compared to more compact cities or so-called smart cities with mixed and diverse land uses, and the result is typically that urban environments which have a dense and smart urban form that are high in density of population, activity and residential are reported proper for walking behavior. In this regard, although the urban form of the studied neighborhoods of this research compared to many previous case studies in terms of those variables, is still more compact, according to the participants’ opinion, they prefer to walkability of their residential spaces, neighborhoods that have diverse land uses (cloth stores, food markets, supermarkets, juices and ice cream shops, home appliances malls and etc.), as well as green and open spaces and environments that have more attractive facets.
Conclusion
In order to achieve the appropriate developmental model to increase the subjective and objective walkability of urban neighborhoods, some steps must be taken to increase the green and public open spaces and redistribute the land uses in accordance with the urban smart growth pattern, by through less dependence on the personal car usage, many challenges of Tehran metropolitan will reduce in line with sustainable development.
Volume 23, Issue 4 (7-2021)
Abstract
Cultural methods such as crop fertilization can affect susceptibility of plants to herbivores by altering plant tissue nutrient. In this study, the life table parameters of the two-spotted spider mite (TSSM), Tetranychus urticae Koch were determined under different chemical fertilizer regimes on resistant bean cultivar (var. Parastoo) under laboratory conditions at 25±1°C, 60±5% RH and a photoperiod of 16:8 (L:D) hour. Treatments included 30, 60, and 100% of the recommended level of urea, ammonium nitrate, and potassium sulfate fertilizers. According to the obtained results, the longest preadult development time was related to individuals reared on the fertilized bean with potassium sulfate 60%, while the shortest period was related to those on 30% ammonium nitrate and 60%urea. The mean fecundity of the individuals reared on fertilized beans with different concentrations of ammonium nitrate (especially 60% ammonium nitrate) were significantly higher than the other fertilizers. The highest and lowest values of intrinsic rate of increase (r) were obtained on beans fertilized with 60% ammonium nitrate and 100%potassium sulfate, respectively. In addition, the values of net Reproductive rate (R0) and the Gross Reproductive Rate (GRR) of TSSM reared on bean fertilized with 60% ammonium nitrate were significantly higher than the other fertilizer treatments. Our findings may provide important information in the design of a comprehensive program for integrated soil fertility management and subsequently integrated management of TSSM in bean fields.
Volume 23, Issue 5 (9-2021)
Abstract
Optimum cropping pattern increases productivity where input resources are limited. An optimized cropping pattern was developed for a region in Moghan Plain, located in the northwestern Iran, to help water supplier in pre-season decision making on water and land allocation. AquaCrop simulation model was calibrated and executed for yield predictions for 11 different crops and 13 diverse soil types. Evaluation of AquaCrop model showed great robustness for a broad range of crops, even for the crops like canola and alfalfa that were undefined for the model. The precise generated crop water functions revealed the ideal conditions for water allocation by considering the impact of the existing limitation in monthly water availability on optimum cropping pattern without imposing any manipulation. Optimum cropping pattern based on water productivity (OCPWP) was identified by LINGO software. Integrating AquaCrop model and LINGO optimization problem solver created a Decision Support System (DSS) for technical analysis at the regional level. The created DSS is able to support the OCPWP in terms of the complex regional crop-mixture acreage. The ecological considerations introduced diverse winter crops to benefit from autumn precipitations. This strategy decreases irrigation requirement and saves some water for spring/summer high water-demanding crops like alfalfa and cotton, which generally enhances the system resiliency. The generated DSS revealed that 8,762 m3 water ha-1 was required for optimum cropping pattern, which is 8% lower than the maximum and 3% more than the average available water.
Volume 23, Issue 5 (May 2023)
Abstract
The non-reproducibility of the measured results of a work piece by reference laboratories is a problem that often causes differences of opinion in production workshops and doubts about the adjustment of production devices with the results provided by laboratories. In this paper, the effect of geometric parameters created by machining on the ability to measure control tools through statistical techniques of quality engineering is investigated, so that first a piece was subjected to drilling and machining, after measurements The exact diameter of the hole with geometric deviation was determined to be cylindrical error to 0.01 mm. Then it was examined with two common measuring systems of air gauge and coordinate measuring machine (CMM) and the capability of the instruments was calculated as follows through the mini-tab software. Capability of air gauge (Cg) in measuring the diameter of hole was 0.27 and capability of CMM device in controlling the said diameter was 0.28. After removing the scattering caused by geometric parameters to calculate the ability of measuring instruments, The power of the instruments was improved to 1.20 in the wind gauge and 1.05 in the CMM and finally, by removing or reducing the geometrical error of the work piece, It should be noted that in this study, after removing the error of workpiece the lack of repeatability in the air gauge increased from 74% to 16.66% and in the coordinate measuring machine (CMM) from 70.80% to 19.13%.
Volume 23, Issue 10 (October 2023)
Abstract
In this research, processing and 3D printing of PETG-ABS-
Volume 23, Issue 10 (October 2023)
Abstract
Smart materials can react to environmental changes like living organisms and adapt themselves to environmental conditions and changes such as changes in temperature, electric current, magnetic field, light, humidity, etc. Using 3D printing to process smart materials is a new approach known as 4D printing. In this research, processing, manufacturing and 3D printing of PETG-ABS in three weight percentages of 70/30, 50/50 and 30/70 were done. The results of SEM also confirmed the compatibility of these two polymers. In all PETG-ABS mixtures, a combination of sea-island and drop-matrix morphology was observed, and for the 30/70 and 30/70 blends, phase droplets dispersed in the matrix were clearly observed. The results of mechanical properties also showed that as the percentage of ABS in the mixture increases, the tensile strength increases and the elongation decreases. The results obtained from the shape memory test indicate the existence of the ability to program the shape memory property in 4D printing mixtures. As expected, the increase in the weight percentage of ABS was associated with the disorder in the recovery of the mixtures, so the mixture with 70% by weight of PETG and 30% by weight of ABS showed the most favorable shape memory properties.