S. Soleimani , M. Yousefzadi , H. Rezadoost ,
Volume 9, Issue 4 (Fall 2018)
Abstract
Aims: Sea urchins have been extensively studied due to the commercial importance of their gonads in the global industry. Although after removal of the edible gonads, the remaining shell and spines are usually discarded, they are known to possess various polyhydroxylated naphthoquinone (PHNQ) pigments. The aim of the present research was quantitative and qualitative identification of PHNQ pigments from shell and spine of Echinometra Mathaei of the Persian Gulf.
Materials and Methods: In this experimental study, the Echinometra mathaei was used as the sea urchin test sample. Sea urchins were collected in 2013 from Zeytoon Park in Qeshm Island, Persian Gulf. Shell and spine pigments were extracted by hydrochloric acid from sea urchin. Then, the quantity of Naphthoquinone compounds was evaluated by spectrophotometric and their quality was evaluated by Liquid chromatography–mass spectrometry (LC-MS) and High-performance liquid chromatography (HPLC). The data were analysed by ANOVA and Duncan's new multiple range test at 5% probability level, using SPSS 19 software and the diagrams were drawn by Excel 2013 software.
Findings: The most pigments were Spinochrome A, C, B, and Echinochrome A, respectively. The presence of PHNQ pigments were confirmed in pigments Spinochrome B and C, Echinochrome A, and Spinochrome A, respectively.
Conclusion: The presence of each of the four pigments in shell and spine pigments is confirmed by quantitative and qualitative methods. The most pigments are Spinochrome A, C, B, and Echinochrome A, respectively.
Volume 13, Issue 2 (Summer 2023)
Abstract
Aims: Today, the energy crisis has become a global problem, and all countries are involved in this crisis, so solutions with small results can lead to significant changes on a macro scale. Passive cooling strategies are a method to reduce energy consumption in buildings and help improve and promote energy management in hot climates.
Methods: The current study analysis ventilation performance related to constructing four-story buildings. Furthermore, there is a heavy investigation into the mechanical aspects of ventilation; hence this research is going to fill the gap in the architectural view of the ventilation system. The modeling uses energy software (Design-Builder).
Findings: Studies have been conducted to investigate the position of the stack, and the earth's rotation, in addition to changes in the materials of the stack in the residential area of Dezful city. The most frequent residential land size in the residential area of Dezful is 10x20 square meters. In addition, changing materials has a direct impact on stack ventilation.
Conclusion: The simulation outcomes demonstrated that material and site rotation changes could alter the stack's performance, meaning that glass can be more effective than aluminum. Still, the position of the stack in the plan does not make a significant difference in the stack's performance. The result is outstanding for architects and all people working in this field, which can be a guideline in designing energy-efficient.
Volume 22, Issue 4 (7-2022)
Abstract
Tubular members, due to their convenient equipment installation and high-strength performance, are widely applied in the support system of offshore platforms such as jack-ups and jackets. In most steel tubular structures; the circular hollow section (CHS) members are mainly joined using welding. Commonly, one or more braces are welded directly onto the surface of a chord member to form that so named welded connection. So far, some techniques to improve the performance of tubular connections have been proposed. Most of these methods (e.g., internal ring, doubler plate) can only be used for structures during the design, but there are only a few techniques (e.g., outer ring, FRP) which can be applied during both fabrication and service. This paper studies the static strength of CHS X-joints reinforced with external ring subjected to axially tensile load. The SOLID186 in ANSYS version 21 was used to establish the finite element (FE) models of the tubular X-joints. Validation of the FE model with experimental data showed that the present FE model can accurately predict the static behavior of the external-ring stiffened and un-stiffened tubular X-joints under tension. Afterwards, 143 FE models were generated and analyzed to investigate the effect of the joint geometry and the external ring size on the ultimate strength, failure mechanisms, and initial stiffness through a parametric study. In these models, both geometric and material non-linearity were considered. Moreover, the welds joining the chord and brace members were modeled. Results indicated that the ultimate strength of the ring stiffened X-joints under brace tension can be up to 289% that of the ultimate strength of the corresponding un-stiffened joint. Also, the increase of the β (the ratio of the brace diameter to chord diameter) results in the increase of the ultimate strength and initial stiffens (in a fixed chord diameter). Because, the increase of the β leads to the increase of the brace diameter. The increase of this member results in the increase of the joints stiffness. In addition, the decrease of the γ (the ratio of the chord radius to chord thickness) leads to the remarkable increase of the ultimate strength. Also, the increase of the τ (the ratio of the brace to chord thickness) leads to the increase of the ultimate strength (in a fixed chord thickness). However, it is not remarkable. Moreover, the comparison between failure modes of reinforced and un-reinforced joints showed that the ring can significantly improve the failure mechanisms. Also, the ring can remarkably increase the initial stiffness. Despite this significant difference between the ultimate strength, failure mode, and initial stiffness of unreinforced and ring reinforced X-joints under brace tension, the investigations on this type of the reinforced joints have been limited to only three X-joint tests. Also, no design equation is available to determine the ultimate strength of X-joints reinforced with the external ring. Therefore, the geometrically parametric study was followed by the nonlinear regression analysis to develop an ultimate strength parametric formula for the static design of ring stiffened X-joints subjected to brace tension. The proposed formula was evaluated based on the UK DoE acceptance standard.
