فصلنامه فناوری آموزش
پیاپی 1 (پاییز 1385)

Analyzing the flow on dams by numerical methods compared to the physical model preparation is the most efficient way to reduce costs and time. In general the type of method used, flow analysis on overflows in its permanent condition requires solving the category of differential equations involved called Navirastox equations in order to make the free surface of the flow very complex and uneconomical.One type of equation used in overflows is the use of medium depth equation model, or in other words, shallow water equations that result from integrating the Navier-Stokes equations in depth and applying boundary conditions of surface and substrate. Intermediate depth equations, also known as shallow water equations, are mainly used to simulate currents where the velocity value is constant at depth of flow and the pressure distribution at depth is hydrostatic.Due to the complexity of the equations and the lack of a precise answer, different numerical methods have been developed to solve the equations governing the physical phenomena.One of the newest of these methods is the set of methods without a network, which has been introduced in the last two decades to solve differential equations, each of which has its own advantages and disadvantages.Dissociation of the problem in many non-networked methods leads to integral equations, the solution of which requires numerical integralization and the introduction of gaseous points and related weights along with networking.In this paper, the least squares method is used to solve shallow water equations.At least discrete squares have been used in the dissection phase of the differential equation to achieve algebraic equations, as well as the minimum weight squares of the data in order to obtain the values ​​of the form functions.The most important advantage of this method should be considered in eliminating the steps of integrating the process of calculating the matrices of the coefficients and also supporting it without networking in the real sense.Correction of the method has been done by numerical analysis of the flow on the overflow of one of the dams of the country and its comparison with the results related to the speed and water level in the physical model.

In this paper, the effect of microsilica on the short-term mechanical properties of high-strength concrete is discussed. Nowadays, due to the fact that the use of microsilica in high-strength concrete has become very common, it is very important to know the effect of this material on different characteristics of concrete. The relationship between resistance, the sequential elastic modulus and the return elastic modulus is one of the cases discussed in this study.Another effect has been the length of the wet storage period on the long-term strength of these concretes. In the laboratory work performed in this study, the ratio of water to cement materials and the total amount of cement materials are 0.35 and 500 kg / m3, respectively. The percentage of microsilica substitutes for cement was 0, 6, 8, 10 and 15%. The 28-day strength of the concrete in question was between 58 and 70 megapascals. To study the effect of storage conditions on the long-term resistance of these types of concretes, the 400-day resistance of the samples kept in saturated conditions until the test was compared with the samples stored in these conditions for 7 days.The result is that long-term processing has little effect on the long-term strength of microsilica concrete. This is not true of microsilica-free concrete. Research on the relationship between resistance and modulus of elasticity and modulus of return elasticity also shows that the model proposed by the ACI 318 regulations does well in these high-strength concretes similar to this research predicts.

Open urban spaces and contemporary urban neighborhoods are not compatible with the physical and mental characteristics of Iranian male and female students. The per capita restriction of educational spaces in schools threatens the quantitative and qualitative limitation of contemporary residential homes and the prevalence of students' environmental lifestyle machine health patterns. Symptoms such as students' high dependence on horseback riding from home to school, construction of schools without desirable open spaces, expansion of apartment living and housing at least without yard and desirable open spaces, continuous TV viewing, excessive computer use, nutrition patterns Unhealthy and the prevalence of phenomena such as overweight and obesity, social avoidance and depression of some students are a confirmation of the problem of students' environmental health.In such a situation, improving urban environments and redeveloped spaces can be effective in changing some unhealthy patterns of students' perceptions and behaviors. The present article tries to introduce some of the planning and environmental design capabilities of residential neighborhoods compatible with the growth and physical and mental health of children and adolescents.Planning and designing pedestrian and bicycle paths from home to school, proper location and design of social schools, planning and design of access networks and connected local sidewalks, planning and design to prevent crime in the neighborhood, traffic calming And expanding neighborhood safety and tranquility, improving and developing neighborhood and neighborhood parks, designing beautiful local streets with environmental design and furniture and natural landscapes and rows of street trees, expanding mixed and diverse local uses and controlling average residential density to In order to increase the access to the services required by students and the socio-local interaction of students, practical solutions are suggested.Also, the development of specialized interdisciplinary research by programmers and environmental and transportation designers with students' general growth and health specialists is one of the proposed research fields.

For cellular mobile users, forced disconnection of a conversation is more undesirable than blocking and rejecting initial communication requests. Various traffic prioritization schemes seek to reduce the forced disconnection of conversations that require channel replacement.In this paper, while reviewing and presenting conventional methods without prioritization, with FIFO and MBPS queuing, with a reserved channel and a combination with queuing and reserved channel, a mobile cellular telecommunication system is considered by considering two types of initial requests and in Now, the connection needs to be replaced, the simulation has been simulated and the results of simulating different methods have been extracted according to the conventional evaluation criteria "probability of forced disconnection" and "probability of blockages" and a comparison has been made between these methods. The results of simulations presented in this study show that the MBPS queuing method is better than the FIFO method and these two methods, while having the possibility of optimal traffic jams, have a much lower probability of forced disconnection than the non-prioritized method.The combined method works better than the reserved channel method because it has the advantages of the reserved channel method and does not have long queues. The results of this study will be useful in selecting the appropriate method and considering the key parameters of each method such as the length of the queue in the queuing methods and the number of channels reserved in the methods based on the reserved channel.

Determining the stress intensity coefficient is the main parameter in reservoir design, and what in the linear failure mechanism controls the crack behavior is the value of the stress intensity coefficient. There are different ways to estimate this value. The weight function method is widely used as one of the stress intensity estimation methods. In this paper, the weight function based on estimating the crack displacement function is obtained using modeling in software in a specific geometry of the ball tube. Then, using the weight function, the stress intensity coefficient and the fatigue life of the ball tube in the case of autophagy, using the actual behavior of the material, are obtained and compared with the available results. The method presented in this paper is a general method that can be applied to any geometry of the tank with any number of internal or external cracks and any relative length of cracks.

Since 1970s the use of laser based range-finders has become a necessary part of many military and domestic systems. According to the needs and the circumstances, many different types of such systems have been developed and their technologies are adapted to the local needs. Distance or displacement measurement in the medium range is mainly divided to three groups; time of flight, frequency modulation continuous wave, and phase-shift laser range finder. In this paper we present the design, implementation and/or simulation of three such systems and compare their characteristics.

Abrasion of industrial concrete floors is a major problem resulting in their lower service lives. Attempt has been made to relate the abrasion resistance of concrete to its compressive strength. However there are other factors which influence the abrasion resistance of concrete. In this study, several concrete mixtures containing different types of cements, aggregates, admixtures and additives such as silica fume and styrene butadiene rubber (S.B.R) polymer were made to assess their abrasion resistances. All concrete specimens were tested for wear action in accordance with ASTM and EN standard test methods. Based on data obtained from the tests, an empirical model was proposed to evaluate the abrasion resistance of different concretes. Results of this investigation show that the incorporation of silica fume, S.B.R polymer and granite aggregates in concrete improve its abrasion resistance. The proposed mathematical model is capable to predict the abrasion resistance of concrete and provide a guide for selection of materials to produce more durable concrete when subjected to wear action.

The purpose of this investigation was to study the effect of bonding behavior of concrete substrate and repair materials. Three different cementitious or modified-cementitious repair materials and three surface roughnesses were studied. Repair materials were ordinary mortar, modified cementitious mortar by silica fume and modified cementitious mortar by styrene butadiene rubber latex. Surface preparations were smooth surface, rough surface and epoxy resin adhesive as a bonding agent. The method used for evaluation of bond strength was pull-off test. the influence of the electrical conductivity of repairing materials was analyzed by rapid chloride permeability test. Finally, the performance of the adhesives was evaluated considering both the bond strength and electrical conductivity. Results obtained from these tests indicated that the roughness of substrate surface has a main effect on the performance of bond between adhesives and concrete. There are not great differences in bonding strength between various repairing materials but considering electrical conductivity, modified cementitious mortars are better materials for using in corrosive environments to increase service life of repaired structures.