Showing 6 results for Hafezi
Volume 6, Issue 2 (9-2017)
Abstract
Growth indices (WG and SGR), food (FCR) and protein efficiency (PER and PCE) of fingerling Nile tilapia, Oreochromis niloticus,were evaluated in 3 synchronous examinations with 12 treatments in triplicates. Groups of control, canola meal (at rates of 25, 50, 75 and 100%), cottonseed meal (at rates of 15, 25, 35 and 45%), as the replacements of expensive protein sources (fish meal and soybean meal), and azolla (at rates of 13, 21 and 29% of diet) were studied. Growth indices, total food intake and protein intake of the control were the highest of all. They decreased with increase in plant protein in every group (p<0.05). FCR and protein efficiency indices didn’t show significant differences (p>0.05) between control and canola meal (at rates of 25 and 50%), cottonseed meal (at rates of 15, 25 and 35%) and azolla (at rates of 13 and 21%). Total food intake, protein consumption and growth indices decreased, because all plant protein ingredients were unpalatable. If the problem of palatability is solved, it seems that the expensive protein sources replace with canola meal and cottonseed meal at the rates of 50 and 35% respectively, and azolla can be used at the rate of 21% in diets.
Volume 11, Issue 4 (Winter 2022)
Abstract
Aims: Topology optimization is among contemporary approaches introduced to connect Architecture and Structural Engineering through simultaneous form-finding of the Architecture and Structural design. It is among various optimizations methods in structural engineering, which has been recently adopted in the architectural design process due to its direct effect on the overall form of the structure. This research aims to outline the potentials of this method within the realm of the design process as a framework.
Methods: Given that this research is performed using Finite Element modelling, at first, the theoretical framework of TO within FE software is described briefly and practically. Further on, different examples of the application of this method for architectural design is introduced, and the procedure of utilizing the method within architectural design process by use of related software and algorithms is described.
Findings: Throughout the Architectural design with TO, the effect of the initial design decisions on the resulting forms becomes somewhat unclear; for this purpose, morphology diagrams have been provided for cases similar to the design problem to facilitate the initial decision making of the designer at the initial stages of the design. Morphology diagrams, describing the effect of parameters related to boundary conditions for similar cases, make the design process transparent.
Conclusion: in this paper, a well-defined framework of the TO process and the required information to apply this method in the architectural design process are presented, and its application in the case study of an urban pedestrian bridge is described.
Volume 12, Issue 3 (9-2023)
Abstract
This study was conducted to investigate the effect of adding Bacillus subtilis (IS02) to the diet on survival, biochemical indices, and histological alternations of juvenile wild common carp, Cyprinus carpio, exposed to salinity stress. Juvenile common carp (about 1.1 g) were fed diets containing 0 (control), 2.5 × 108 (pro-8), and 2.5 × 109 (pro-9) cfu/g probiotic for 15 days and then transferred directly to brackish water (13 g/L) and sampled after 3 and 10 days. Diet and sampling time had no significant effect on fish survival, which was above 96% in all treatments. Body moisture and potassium were only affected by sampling time, with moisture decreasing significantly after salinity stress while potassium increased significantly. Whole body sodium in pro-8 treatment did not change significantly during salinity stress, and probiotic treatments had lower chloride levels than the control before and after salinity stress. Adding probiotic to the diet increased glutathione reductase, glutathione peroxidase activity, and reduced glutathione concentration, while decreasing malondialdehyde concentration. Probiotics caused white blood cells infiltration in the kidney tissue. No significant tissue damage was observed in the gill and kidney, compared to the control after salinity stress. This study shows that juvenile wild common carp can tolerate direct transfer to the Caspian Sea without dietary probiotic supplementation. However, probiotic stimulates the kidney immunity, enhances ionoregulation, and increase antioxidant capacity in fish, which can have beneficial effects under field conditions.
Volume 16, Issue 8 (10-2016)
Abstract
A solar-powered robot is a mobile robot powered completely or significantly by direct solar energy. The sun's energy is converted into electric energy by solar panels mounted on the robot. These solar panels are required to be light, because of the important demands for low-energy consumption. As a result of the flexibility of elements of the panels, undesirable low-frequency vibration may occur when the robot moves on a rough terrain. In this paper, a new method for stabilization of solar panels vibration base on trajectory planning for articulated mobile robot is presented. The dynamics of solar panels attached to the robot is derived using Kane’s method. The attitude and configuration of a rover as a function of the terrain on which it moves is determined using inverse kinematics of the robot. The attitude and configuration of a rover is required to approximate the domain of vibration by derived dynamics equations. Base on this approximation, a trajectory planning algorithm is presented that can reduce vibration without significant decrease in the velocity of the robot. The proposed method is simulated for a six-wheeled mobile robot with rocker-bogie structure The obtained results show that the algorithm stable the domain of vibration in allowable area and do not decrease the velocity of the robot significantly.
Volume 17, Issue 4 (7-2015)
Abstract
Soil contamination significantly reduces environmental quality and affects human health. To investigate and assess the effects of land use on the concentrations of some heavy metals in surface soils of Golestan province, 227 soil samples (0-60 cm) were collected from three types of land uses including agricultural lands, natural, and industrial areas. The total metals and metalloids (Cr, Se, As, Cd, Ni, Pb, Zn, Cu, Fe) were extracted and their concentrations were measured in all samples. The results showed that heavy metals accumulations in soil samples of the industrial land uses were higher than agricultural and natural land uses. There was significant correlation among the soils heavy metals (more than 30% for most samples) and also between soil heavy metals and organic carbon content in different types of land uses (average of 40%). Cluster analysis revealed that As and Se had the highest concentration values compared to their corresponding background in most samples and showed the evidence of anthropic effects. Various indices including pollution load index (PLI), modified contamination degree (mCd), and enrichment factor (EF) were used to determine the soil contamination level. The results of PLI and mCd,indicated the higher accumulation of heavy metals at industrial land uses. The enrichment factor of Se and As in soils were higher than the other metals, however, their values showed that anthropogenic activities had not serious effects on the environment quality in the studied area.
Volume 21, Issue 8 (August 2021)
Abstract
The Resin transfer molding (RTM) process is a closed mold process to produce composite products in mass production. This method includes various parameters such as mold temperature, vacuum pressure, injection point, fiber volume fraction, injection pressure and so on. It is only by controlling these parameters that parts with the desired surface quality and high properties can be achieved. In this study, the effect of input parameters of resin transfer molding process including vacuum pressure, injection point and mold temperature on mold filling time, curing time, tensile strength and flexural strength of carbon-epoxy composite was investigated. Each of the input parameter has been investigated at three levels using the RSM full factorial method. Finally, after making carbon/epoxy composite samples with this process, their evaluation in terms of filling time, curing time and mechanical properties have been investigated. The results showed that the injection point has a significant effect on the mechanical properties and production volume of the part in the Resin transfer molding process. According to the results, the optimal sample was determined by prioritization mechanical properties with mold temperature parameters of 106.7° C, vacuum pressure of 0.83 bar and injection point B (one resin input in the middle of the part and two vacuum outputs at the end of the part). Tensile strength of the sample was 546.7 MPa, flexural strength was 759.2 MPa, curing time was 7.3 minutes and mold filling time was 8.6 minutes by software.
