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.

Background: Walking and RUNNING frequency domain analysis of ground reaction forces are associated with injuries. Comparison of frequency domain analysis of ground reaction forces could be useful in rehabilitation of low back patients. The objective of this study was to investigate frequency domain of ground reaction forces during RUNNING in patients with low back pain compared to healthy control ones. Methods: This study was a semi-experimental. The statistical sample of the present study include forty males that divided into a healthy control GROUP (n=20) and a GROUP of patients with low back pain (n=20). A foot scan system (sampling rate: 300 Hz) was used for measuring ground reaction forces in ten regions of the foot during RUNNING. Independent sample t-test was used for statistical analysis. Alpha level was set at p<0. 05. Results: The frequency content with power 99. 5% in the Toe 1 region in low back patients GROUP was significantly greater that that healthy GROUP by 50% (P=0. 017). Also, the frequency content with power 99. 5% in the Toe 1-5 region in low back patients GROUP was significantly lower than that healthy GROUP (P=0. 007). Number of essential harmonics in forth metatarsal in low back patients GROUP was greater than that healthy ones (P=0. 049). Conclusion: Patients with low back pain had lower RUNNING speed than that healthy ones and therefore lower values of most of the components of the frequency may be due to the guarded gait mechanism in these patients. This altered RUNNING speed and lower frequency content is suggestive of a lower mechanical efficiency of RUNNING in patients with low back pain.