The research on tall buildings has been increased due to the demands of suitable spaces. The use of Pyramidal architecture in tall structures has several benefits including the ability to lighten the adjacent buildings and prevention from the closure of the view in urban spaces. However, the seismic behavior of Pyramidal tube structures requires a closer examination of their design and probable behavior under lateral loads. One of the most important parameters in the Pyramidal tapered buildings is the calculation of natural frequency of the vibrating structures (ω). In this study we have proposed new equations and methods for the mentioned calculations which has been compared with software calculations. Many researchers have calculated the free vibration of structures using different methods. One formula to obtain the natural frequency of tube structures is obtained from the fourth-order differential equation (Wang, 1996). An approximate solution in order to analyze the free vibration of tall tube-in-tube buildings have been proposed by different researchers (Lee, 2007; Lee and Bang, 2008; Lee and Tovar, 2014). The modeling of tall building using a beam with varying stiffness and mass subject to the variable axial force caused by simple weight was presented by Mohammadnejad (2015). Free vibration analysis using differential equation has been evaluated by Bozdogan (2009) and Bozdogan (2013). The first natural frequency of tall buildings with a system combined of framed tube, shear core, and belt truss has been calculated under axial force (Kamgar and Rahgozar, 2014; 2015; 2018). A new and simple method of determining the natural frequency of tube structures with tube-in-tube wall has been presented. The novelty of this method refers to the mathematical computation process which is much simpler and shorter. The effect of structure’s weight on the natural frequency of structure has been considered by variable axial force. Tall building is modeled by a beam with variable stiffness and mass along the height of the building. Therefore, the partial differential equation with variable coefficients is used which have been presented by Mohammadnejad and Haji-Kazemi (2018). Furthermore, there is no regular research on the vibrational frequency calculation of Pyramidal tube systems, especially by mathematical methods, or a small number of studies have been done most of which have been done on 90-degree structures with tube systems.

Unlike a single building, determining the performance of two or more buildings next to each other under the effect of wind is very complex due to the inference effect. One of the latest efforts in investigating the interference effect is determining the interference factors and pressure coefficients of a group of tall buildings using Computational Fluid Dynamics (CFD). In this paper, the pressure coefficients and interference factors of a group of tall buildings with different heights placed at different distances due to various wind directions have been studied. The effect of buildings distances and direction of wind load on two groups of four tall buildings on the average pressure coefficients of the buildings in the group has been investigated. For the selected distances, in over 50% of cases by increasing the distance between the tall buildings the average pressure coefficients on buildings increase. In order to show the wind interference effects, the interference factors, i.e. the ratio of pressure coefficients on a building in a group of tall buildings to those of a single building, are calculated and compared. Interference factors show that the maximum and minimum pressure coefficients on a building in a group of tall buildings are up to three times of those of a single building.

Wind loads of high-rise buildings are a key parameter in architectural design. The magnitude and distribution characteristics of wind loads are of great importance for the safety and economy of structural design. The wind loads of high-rise buildings are quite different from those of monomer buildings. The wind-induced interference effect could significantly increase the local wind pressure of buildings, causing potential safety hazards for the main structure and enclosure structure. For the three common high-rise buildings, we adopted the wind tunnel test method to measure the surface pressure of each building. The corresponding Re number was 8. 2×106. This paper studied the shape coefficients, fluctuating wind pressure coefficients and base bending moment coefficient of each building with different wind direction angles and different spacing ratios, and the maximum value of each parameter and the corresponding working condition were statistically analyzed. The results showed that, under any wind direction angle, the fluctuating wind pressure coefficients on all sides of the building were affected by the spacing ratio, and the fluctuation range was large. When the wind angle was 180º, the fluctuating wind pressure coefficients on the sides of Building 1 were most affected by the slope ratio. At this wind angle, the maximum value was 0. 43 at a slope ratio of 5. 0, which was 65% different from the minimum. Partition shape coefficients of some sides and top surfaces changed significantly with the spacing ratio. When the spacing ratio was 5. 0, the base bending moment coefficients in the downwind and crosswind directions reached their maximum values, and the wind direction angles where the maximum values of the base bending moment coefficients in the downwind direction were 40º and 50º, respectively, and the wind direction angle where the maximum value of the base bending moment coefficients in the crosswind direction was 10º. Due to the influence of the wind angle and the building spacing ratio, the wind loads on the facades of the Pyramidal group of buildings varied greatly, and the wind-induced interference effect was evident. The wind load between the building facades in the three buildings was different, and the wind disturbance effect was evident. Therefore, the most unfavorable stress state and interference state of the structure should be comprehensively considered in the wind resistance design of the three buildings. The building spacing ratio should preferably be set to 3. 0, and wind angles of 10º, 40º, and 50º should be avoided whenever possible.

Network marketing phenomenon in which mendacious mediators are eliminated, basically is a useful matter. But the companies so-called Pyramidal schemes misuse this title. In this companies there isn’t any production, consumable goods and useful work and they just constitute the pyramids in which the money belongs to persons in lower level go into the pocket of company and few people who are in the apex of pyramid. These companies are divided into three groups: investment companies, product based companies and companies that offer no product.Every country which has a law about these schemes, recognize them a crime. Rational proof and multiple jurisprudential proof implicate that these activities are illegitimate.

When the density current smashes into the lower dense fluid mass a plunge region will occur. Since the plunge depth bounds between density current and ambient fluid, determining of this point is important. In this research, the hydraulic parameters of density current and bed slope of stagnant fluid were investigated. To achieve the purpose of this research a physical model was built in the hydraulic laboratory of Shahid Chamran University (SCU) and various experiments were performed. In the experiments, the plunge depth at the different discharge of density current and density difference 6, 9, 13 and 16 kg/m3 at three slopes 8, 12 and 16% was measured. Then using Flow-3D under RNG turbulence model, plunge depth was simulated for the same experimental condition. The comparison of results obtained showed that the predicted plunge depth with Flow-3D under RNG turbulence model had a high and satisfactory accuracy. Finding showed that for the 8% bed slope, the results of RNG turbulence model 14% was more than experimental data. While, for the entire slope, the results of RNG turbulence model was predicted 10.5% in average more than measured data. Generally, the statistical investigations showed that the RNG turbulence model with satisfactory precision estimated the plunge point depth.

Context and purpose. Obtaining the private GAP standard for healthy product certification due to costs is out of reach in many small and mediumsized farms among smallholder farmers. groupGAP has provided a much-anticipated alternative where operators and farmers' cooperatives can pay the cost of certification on a cost-sharing basis. Therefore, the purpose of this research was to explain the development strategies of GAP standard with emphasis on groupGAP in the rice production system of Mazandaran province. Methodology/approach. Current research is qualitative and data analysis was conducted in the grounded theory method, during a three-stage process of open coding, central coding, and selective coding. The data collection tool included an in-depth and semi-structured interview with a qualitative content analysis technique, which was analyzed through Maxquda software. The statistical population of the research was 18 experts and specialists of the Agricultural Jihad Organization and managers of the Rice Farmers Cooperative Company of Mazandaran Province, who were selected by the purposeful sampling method. Findings and conclusions. After extracting the concepts of the content analysis of the interviews, 9 conceptual codes out of 30 initial codes were identified in the first stage of coding. After refining and merging, the codes were classified into 3 subcategories. These components include the group certification system, the development of publicGAP programs and the development of private GAP. In the group certificates, the two dimensions of contract system development and guaranteed purchase, the development of the cooperative company for the production of healthy products have been taken into consideration. It is recommended to strengthen the organizations and cooperatives of farmers and exporters, especially to strengthen young farmers and women organizations. Originality. Originality/innovation: Due to the importance of the GAP standard issue and farmers' problems in providing the audit fees and establishment of GAP certificate, so far, no comprehensive study has been carried out in Iran on the development of operational strategies for the establishment of GAP and groupGAP. Therefore, the current research is an attempt to provide a useful framework in explaining GAP standard development strategies with the participation of farmers in adopting the government, private, group and cooperative certification system.

In this paper the morphological umbra sampling scheme is introduced. In addition, a new morphological pyramid is proposed that provides a higher performance than other Pyramidal schemes. The high performance of the proposed pyramid is due to: 1- it is applied not only to spatial dimensions, x and y, but also to the gray levels, 2- in the new scheme, the error signal (image) is non-negative. Results of experiments done on a variety of images have validated the proposed method.

Introduction: Considerable attention is focused on the effects of the electromagnetic field (EMF) due to its wide-ranging use in every day of life. Appliances and various equipments are sources of electromagnetic fields with a wide-range of technical characteristics. Power lines and almost all kinds of household electrical appliances Emit EMF. Epidemiological studies suggest a possible link between EMF exposures and clinically recognized medical disorders in people; in this study we investigated the effect of EMF on frontal cortex of mouse.Methods: 30 BALB/c mice were selected and divided in 2 of experimental & Control groups. Experimental group was exposed to 50 Hz, 0.5mT EMF for 4 hours per days in, 6 days per week for 2 months. Controls was not exposed to EMF but were in the same condition. Animals were killed after 2 months exposing of EMF and the brain were removed and the left frontal lobe of 2 groups was selected. After normal routine processing, slices were stained with cresyl violet for histological examination and evaluated with image tool software. The data were analyzed in highly significantly P< 0.05 with SPSS software.Results: Some histological and degenerative changes were seen in neurons of frontal lobe in experimental group compare to control group. These features were including shrinkage of Pyramidal cell in experimental animals. Statistical results like changes of long diameter of Pyramidal cell was decreased related to the same neuronal cells in control groups P<0.05. Finally the number of Pyramidal cell in experiment groups has decrees in compare with control groups.Conclusion: It can be concluded that long term exposure to EMF has detrimental effects on the morphological changes of neurons of the frontal cortex and may lead to the degenerative phenomenon on the Pyramidal cells.

Background and Objective: As one of the widely used drugs, aspirin (acetyl-salicylic acid, ASA) plays an important role in stroke treatment and prevention. In a previous study, we demonstrated ASA injection at 30 min after ischemia onset is neuroprotective. To determine whether the neurons protected by ASA had a normal ultrastructure, hippocampal CA1 Pyramidal neurons were examined by Transmission Electron Microscope (TEM).Material and Methods: Adult male wistar rats were divided into three different groups (6 animals/ group): Sham-operated, control (48 MCAO+vehicle) and aspirin (48 MCAO+ASA). ASA (30 mg/kg) was injected 30 min after ischemia onset. The animals were killed 2 days after ischemia induction and their brain removed, processed, and examined under a TEM.Results: Apoptotic changes were observed in rats not treated with ASA. In contrast, Pyramidal neuron ultrastructure appeared normal in rats that exhibited neuroprotection (defined at the light microscope level) by ASA when studied two days after ischemia.Conclusion: We conclude that administration of ASA after permanent focal cerebral ischemia remains a considerable therapeutic strategy.