The evaluation of structural responses is key element in the design of ships and offshore structures. Fundamental to this is the determination of the design loads to support the Rule requirements and ...for application in direct calculations. To date, the current design philosophy for the prediction of motions and wave-induced loads has been driven by empirical or first-principles calculation procedures based on well-proven applications such as ship motion prediction programs. In recent years, the software, engineering and computer technology available to predict the design loads imposed on ships and offshore structures has improved dramatically. Notwithstanding, with the stepwise increase in the size and structural complexity of ships and floating offshore installations and the advances in the framework of Rules and Standards it has become necessary to utilise the latest technologies to assess the design loads on new designs. Along the lines of the recommendations from the International Ship and Offshore Structures Committee (ISSC) I.2 on Loads this paper reviews some of the recent advances in the assessment of loads for ships and offshore structures with the aim to draw the overall technological landscape available for further understanding, validation and implementation by the academic and industrial communities. Particular emphasis is attributed on methodologies applicable for the prediction of environmental and operational loads from waves, wind, current, ice, slamming, sloshing and operational factors. Consideration is also given to deterministic and statistical load predictions based on model experiments, full-scale measurements and theoretical methods.
•Loads on ships and offshore structures support classification rule requirements and procedures.•47% of research efforts focus on prediction and validation of wave induced loads.•Engineering and computing technology has improved dramatically.•Combining computer, statistical, full scale and experimental methods eliminates uncertainties.
A broad spectrum of anomalies of sexual differentiation may exist at birth, which can be unreported until adolescence. A 17-year-old patent with female phenotype came with complaints of primary ...amenorrhea. On imaging (ultrasound and MRI) uterus and bilateral ovaries were absent. Small blind-ending vaginal pouch was noted along with features suggesting bilateral cryptorchidism. No definite male external genitalia/scrotal sac was seen except for subtle rudimentary bulbo-cavernous muscles. Karyotyping confirmed 46 XY consistent with Male Pseudohermaphroditism.
Male pseudohermaphroditism refers to a condition that affects 46, XY individuals with differentiated testes who exhibit varying degrees of feminization. In these cases there is a spectrum of external genitalia; some individuals are completely phenotypically female. Androgen insensitivity syndrome (AIS), also known as the testicular feminization syndrome, results from end-organ resistance to androgens, particularly testosterone. As the appearance of the external genitalia often is not distinctive enough to make a specific diagnosis, this must be accomplished by clinical findings along with a combination of imaging, cytogenetic and biochemical studies. Ultrasound and MRI studies are extremely useful to diagnose such conditions at the earliest as these patients have an increased incidence of malignancy in the undescended testes. The treatment is influenced by genital tissue responsiveness to androgens and reconstructive surgical procedures. There is a need for counselling regarding pubertal development, sexual performance and fertility.
A 17year old patent came with complaints of primary amenorrhea. On examination patient has normal external female genitalia, with developed breast. On laboratory correlation, it shows high testosterone level: 881 ng/dL and Normal progesterone level: 0.182 ng/mL. On karyotyping, it shows 46XY karyotype. On USG: Uterus is not well appreciated. There is iso-echogenic oval shaped soft tissue seen in bilateral inguinal regions with vascularity within-likely to be gonads. On MRI: Absence of uterus and bilateral ovaries are confirmed with evidence of symmetrical oval-shaped soft tissue lesions identified within bilateral inguinal canals - consistent with bilateral cryptorchidism. Male pseudohermaphroditism refers to a condition that affects 46, XY individuals with differentiated testes who exhibit varying degrees of feminization.
In cases of male pseudohermaphroditism, there is a spectrum of external genitalia; some individuals are completely phenotypically female, whereas others appear to be normal males with varying spermatogenesis and/or pubertal virilization. As the appearance of the external genitalia often is not distinctive enough to make a specific diagnosis, this must be accomplished by clinical findings along with a combination of cytogenetic, biochemical, and radiologic studies. Sonographic and radiographic studies are often used initially to evaluate such conditions. Male pseudohermaphrodites all possess testes yet exhibit incomplete virilization of the genital ducts and/or external genitalia. The findings depend on the underlying defect. Complete androgen insensitivity (testicular feminization) is an X-linked recessive disorder in which the absence of cytoplasmic testosterone receptors prevents specific gene activation and subsequent differentiation of the external genitalia. In this disorder, the external genitalia are completely feminized, while in the other forms of male pseudohermaphroditism various degrees of virilization occur. The absence of internal female genital tract structures reflects the synthesis of active Mullerian regression factor by the testes, which may be maldescended. Multiplanar MR images will confirm the absence of a uterus and demonstrate intraabdominal or inguinal testes. Integrated imaging in the form of ultrasound, genitography and MRI is important in demonstrating the anatomy, classification, possible effects or congenital malformations in other organs, warning patients of any risk of neoplasia and guiding the clinician to plan other investigations, hormonal replacement or reconstruction surgery if required. References Tanaka YO, Mesaki N, Kurosaki Y, et al. Testicular feminization: role of MRI in diagnosing this rare male pseudohermaphroditism. J Comput Assist Tomogr 1998;22(6):884-888. Nakhal RS, Hall-Craggs M, Freeman A, et al. Evaluation of retained testes in adolescent girls and women with complete androgen insensitivity syndrome. Radiology 2013;268(1):153-160.
The aim of this paper is to critically assess the methods used for the evaluation of wave-induced loads on ships examining analytical, numerical and experimental approaches. The paper focuses on ...conventional ocean going vessels and loads originating from steady state and transient excitations, namely slamming, sloshing and green water, for the latter, and including extreme or rogue waves, as well as the more occasional loads following damage. The advantages and disadvantages of the relatively simpler potential flow approaches against the more time consuming CFD methods are discussed with reference to accuracy, modeling nonlinear effects, ease of modeling and of coupling with structural assessment procedures, suitability for long term response prediction and suitability for integration within design and operational decision making. The paper also assesses the uncertainties involved in predicting wave-induced loads and the probabilistic approaches used for the evaluation of long term response and fatigue analysis. The current design practice is reviewed and the role of numerical prediction methods within the classification framework and goal based design approach discussed. Finally the suitability of current developments in prediction methods to meet the needs of the industry and future challenges is assessed.
•Critical assessment of analytical, numerical and experimental approaches for the evaluation of wave-induced loads on ships.•Advantages and disadvantages of relatively simpler potential flow against more time consuming CFD methods are discussed.•Uncertainties in predicting wave loads & probabilistic approaches for long term response & fatigue analysis are discussed..•The role of numerical prediction methods within the classification framework and goal based design approach discussed.
The problem of determining the bounds of applicability of perturbation expansions in terms both of the system parameters and the state-space variable amplitude is a key point in the perturbation ...analysis of nonlinear systems. In the present paper an analysis in a finite neighborhood of a Hopf bifurcation is presented in order to analyze the conditions under which a Normal Form zero-divisors-based approach fails to describe the local dynamics and, therefore, a small divisor approach is required. The condition of “smallness” referred to the divisors is analyzed from both a qualitative and a quantitative point of view. Finally, a simple but effective analytical and numerical example is introduced to illustrate the theoretical issues along with an interpretation within a codimension-two framework.
In this study, the polar metabolite profile of commercial yoghurt samples produced in Sardinia (Italy) from milk of local sheep and goats was studied by GC-MS and multivariate statistical data ...analysis (MVA). Milks underwent the same manufacturing procedures and yoghurts were analysed one day post-manufacture. Results of discriminant analysis indicated that the two yoghurt types had very different metabolite profiles, with different levels of health promoting compounds. Goats' milk yoghurt was richer in free amino acids, γ-aminobutyric acid, pyroglutamic acid and β-phenyllactic acid when compared with yoghurt produced with sheep's milk. Sheep's milk yoghurt was characterised by higher levels of myo-inositol, N-acetylgalactosamine and N-acetylglucosamine. Comparing yoghurt metabolites with those of the original milk, it was found that goats' milk underwent stronger metabolite changes after inoculum. The comparison between the two yoghurt types gave us a deeper insight on the effects of manufacture on different milks.
In this paper, the mechanism of limit-cycle excitation is investigated for an aeroelastic system with structural nonlinearities. The analysis is performed on a simplified aeroelastic model retaining ...only two structural modes (first bending and first torsional modes) and with a simplified description of both unsteady loads due to wing oscillation and external gust excitation. Two cases are considered, without and with gust excitation. In the first case, normal form analysis is employed to give an approximation of the basin of attraction of stable limit cycles in the space of initial conditions. In the second case, a critical gust intensity for a given gust gradient leading again to undamped oscillations is identified.
A three-degree-of-freedom aeroelastic typical section with a trailing-edge control surface is theoretically modelled, including nonlinear springs for both the nonlinear description of the torsional ...stiffness and of the hinge elastic moment. Furthermore, augmented states for linear unsteady aerodynamic of 2-D incompressible potential flow, have been considered in the model. First, the system response is determined by numerically integrating the governing equations using a standard Runge–Kutta algorithm in conjunction with a ‘shooting method’. The numerical analysis has revealed the presence of stable and unstable limit cycles, along with stability reversal in the neighborhood of a Hopf bifurcation. Consequently, the equations of motion are analysed by a singular perturbation technique based on the normal-form method. This method, originally introduced by strictly applying a resonance condition, is herein extended by applying a near-resonance condition in order to improve the semi-analytical description of the stability reversal behavior. Therefore, amplitudes and frequencies of limit cycles depending on the flow speed
V are obtained from the normal-form equations, and the terms which are essentially responsible for the nonlinear system behavior are identified.
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