Interrelationships among Egg, Larvae and Maternal Characteristics in Persian Sturgeon Acipenser persicus

This study was aimed to observe the correlations among egg, larvae and maternal characteristics of Persian sturgeon. A total of 41 females were used and the variables including fertilization rate, incubation survival rate, larvae survival rate during yolk sac absorption (before feeding), and larvae survival rate after first feeding were determined. As a result, fertilization rate was positively correlated with three variables: incubation survival, larvae survival during yolk sac absorption, and GSI (gonadosomatic index). Also, maternal size (age, weight, total length) did not show a significant relation (P > 0.05) with incubation survival, larvae survival during yolk sac absorption and larvae survival at first feeding stage

2-Amino­pyridinium diphenyl­phosphinate monohydrate

In the crystal of the title hydrated salt, C5H7N2 +·C12H10O2P−·H2O, the cations, anions and water mol­ecules connected by N—H⋯O and O—H⋯O hydrogen bonds into a layer along the bc plane; the phenyl rings protrude into the space between the layers. The dihedral angle between rings of anion is 86.1 (1)°

ASSESSMENT OF FATIGUE RELIABILITY FOR JACKET-TYPE OFFSHORE PLATFORMS CONSIDERING DYNAMIC BEHAVOIR

peer reviewedIn order to traditionally investigate the strength of marine structures, the structure is subjected to a maximum static load. However, the marine structures are usually suffering environmental forces varying with time. Wave forces are the most important time dependent loading that causes fatigue in structural elements and joints. In this paper different methods base on S-N curve and linear elastic failure mechanics are presented. The governing equations and theories that are used in each method are expressed and the application of each method will be discussed. The two main methods of deterministic analyses are: stressbased approach (S-N curve approach) and linear elastic fracture mechanics (LEFM) approaches. These approaches are applicable to different analyzing strategies, ie the first approach is used for cases in which general form of fatigue is dominant, but the latter involves the calculations of reliability as functions of crack geometry and its boundary conditions. The SPD12C jacket platform is also modeled as a case study and the results of fatigue reliability analysis are presented. In this paper a comprehensive method is presented to accurately predict the reliability of offshore platforms. This method is based on S-N curve and the results are compared with the fatigue life of joints. Due to nonlinear interaction of soil and piles and the other affecting parameters such as flexibility of joints, non Gaussian procedure of loading, and nonlinearity of reaction force, the precise analyzing of stress levels will be impossible and a complex numerical analysis could only give limited information about the statistical properties of stress. In order to perform the fatigue analysis and predicting the cycles of stress SACS was used which is known as a powerful software in designing and analyzing offshore structures. In this paper the whole structure was modeled subjected to different forces such as wave and sea currents. The effects of parameters such as marine growth and interaction of soil and piles are also included. The latter is shown to have a significant effect on determination of fatigue life of the platform

Applications of machine learning approaches in aerodynamic aspects of axial flow compressors: A review

A compressor is one of the key components of a gas turbine engine and its performance and characteristics significantly affect the overall performance of the engine. Axial flow compressors are one of the most conventional types of compressors and are widely used in turbine engines for large-scale power generation. Intelligent techniques are useful for numerical simulation, characterization of axial compressors, and predicting their performance. The present work reviews studies applying different intelligent methods for performance forecasting and modeling different aerodynamic aspects of axial compressors. Corresponding to the outcomes of the considered research works, it can be expressed that by using these methods, axial compressors can be characterized properly with acceptable exactness. In addition, these techniques are useful for performance prediction of the compressors. The accuracy and performance of these methods is impacted by several elements, specifically the employed method and applied input variables. Finally, some suggestions are made for future studies in the field

Assessment of an Tentative Novel Body of X-Ray tube in order to Decrease the Applicability Limitation in Medical Practice

The output of X-ray, especially in the field of required energy for diagnosing the disease is very low (in diagnosing lamps, it is less than 1%). In this kind of lamps the rest of the electrical energy is transformed to heat. This considerable amount of heat induces a myriad of too many limitations in choosing higher levels of radiation, particularly in specialized techniques. This process is the outcome of X-ray generating mechanism; thus, one of the proper solutions to reduce the limitations caused by generating high heat is enhancing the cooling rate in these lamps. In this project, the design and alloy of the framework, surface and the substance were altered in a manner whereby the cooling rate increases or heat accumulation in lamps decreases. This surface was designed in the shape of a two-part disc with wings whose substance is the same as the framework. The substance of the framework is made of an alloy of copper and chromium. The disc shape of the framework and its aerodynamic compatibility further expose its contacting surface to the air.  This contacting surface can be expanded to 10 times more than the ordinary frameworks. The heat conductivity coefficient of this alloy is approximately 220 w/ mk, which in comparison with the heat conductivity coefficient of the ordinary lamps framework, being about 10, is 22 times more. The results of the tests reveal that the cooling rate of this framework is 10 times (or 1000%) more than the ordinary one. This process reduces the limitations of choosing radiation factors with the same proportio

Standardization of a trauma symptoms checklist for children

Background: The aim of this study was to standardize and assign validity and reliability of the Trauma Symptom Checklist for Children (TSCC-A). Methods: Normative data for the TSCC-A were based on 3042 students participating in a prevalence child abuse study in 19 different locations of Tehran and 140 participants who had been refered to the run-away children centers in Tehran. After the TSCC was validated on run-away and abused children, it was made available to researchers doing larger studies on a normative group. Results: Reliability analysis of the TSCC-A scales in the normative sample demonstrated high internal consistency. The evidence for its validations (convergent, discriminant and construct validity) showed that they were significantly acceptable. Conclusion: This paper presents data demonstrating the psychometric reliability and validity of the TSCC-A scales in the Iranian student population. We suggest to include the TSCC-A in a battery of relevant standardized tests