Random vibration analysis of space flight hardware using NASTRAN

During liftoff and ascent flight phases, the Space Transportation System (STS) and payloads are exposed to the random acoustic environment produced by engine exhaust plumes and aerodynamic disturbances. The analysis of payloads for randomly fluctuating loads is usually carried out using the Miles' relationship. This approximation technique computes an equivalent load factor as a function of the natural frequency of the structure, the power spectral density of the excitation, and the magnification factor at resonance. Due to the assumptions inherent in Miles' equation, random load factors are often over-estimated by this approach. In such cases, the estimates can be refined using alternate techniques such as time domain simulations or frequency domain spectral analysis. Described here is the use of NASTRAN to compute more realistic random load factors through spectral analysis. The procedure is illustrated using Spacelab Life Sciences (SLS-1) payloads and certain unique features of this problem are described. The solutions are compared with Miles' results in order to establish trends at over or under prediction

Transient loads analysis for space flight applications

A significant part of the flight readiness verification process involves transient analysis of the coupled Shuttle-payload system to determine the low frequency transient loads. This paper describes a methodology for transient loads analysis and its implementation for the Spacelab Life Sciences Mission. The analysis is carried out using two major software tools - NASTRAN and an external FORTRAN code called EZTRAN. This approach is adopted to overcome some of the limitations of NASTRAN's standard transient analysis capabilities. The method uses Data Recovery Matrices (DRM) to improve computational efficiency. The mode acceleration method is fully implemented in the DRM formulation to recover accurate displacements, stresses, and forces. The advantages of the method are demonstrated through a numerical example

Modeling input validation in UML

Security is an integral part of most software systems but it is not considered as an explicit part in the development process yet. Input validation is the most critical part ofsoftware security that is not covered in the design phase of software development life-cycle resulting in many security vulnerabilities. Our objective is to extend UML to new integrated jramework for model driven security engineering leading to ideal way to design more secure software. Input validation in UML has not been addressed previously, hence we incorporate input validation into UML diagrams such as use case, class, sequence and activity. This approach has some advantages such as preventing jrom common input tampering attacks, having both security and convenience in software at high level of abstraction and ability of solving the problem ofweak security backgroundfor developers

Fast Subpixel Full Search Motion Estimation

Motion estimation is one of the most important part in video coding, where only the difference between the current and reference frames will be coded by the encoder.There are many advancements happening in motion estimation techniques. The proposed algorithm provides high precision matching and even reduces the errors during compensation. The algorithm also reduces the computation time when compared to traditional Block matching techniques. It mainly aims at the motion estimation with subpixelaccuracy without interpolation, it is the combination of Block matching and the optical flow method.Fast computation may be evaluated by experimental results while even motion vectors are more accurate reducing the PSNR

Maximally robust controllers for multivariable systems

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Distribution of finfish resources along southeast coast of India in relation to certain environmental parameters

This paper embodies the distribution pattern of major finfish resources along the southeast coast of India as observed during the cruises operated by FORV Sagar Sampada. A total of 16 cruises (1985-90) operated along latitude 7° 15'- 15°00' N and longitude 75°50'- 82°3r E hauled a total catch 37.5 tonnes with a catch rate of 537 kg/hr. The catch was constituted mainly by threadfin breams (43%), perches (14%), barracudas (9.72%), carangids (8.56%) and elasmobranchs (4.81%). Seasonally higher catch rates were obtained during July- September period. Depth range of 60 - 80 m had denser population of finfish resources. Water temperature and salinity appeared to influence the distribution of major finfishes more than dissolved oxygen. Groups such as threadfin breams were found preferring cooler waters of Wadge Bank area, while barracudas appear to occupy warmer waters of Gulf of Mannar

A Feasibility Study of Quantifying Longitudinal Brain Changes in Herpes Simplex Virus (HSV) Encephalitis Using Magnetic Resonance Imaging (MRI) and Stereology.

OBJECTIVES: To assess whether it is feasible to quantify acute change in temporal lobe volume and total oedema volumes in herpes simplex virus (HSV) encephalitis as a preliminary to a trial of corticosteroid therapy. METHODS: The study analysed serially acquired magnetic resonance images (MRI), of patients with acute HSV encephalitis who had neuroimaging repeated within four weeks of the first scan. We performed volumetric measurements of the left and right temporal lobes and of cerebral oedema visible on T2 weighted Fluid Attenuated Inversion Recovery (FLAIR) images using stereology in conjunction with point counting. RESULTS: Temporal lobe volumes increased on average by 1.6% (standard deviation (SD 11%) in five patients who had not received corticosteroid therapy and decreased in two patients who had received corticosteroids by 8.5%. FLAIR hyperintensity volumes increased by 9% in patients not receiving treatment with corticosteroids and decreased by 29% in the two patients that had received corticosteroids. CONCLUSIONS: This study has shown it is feasible to quantify acute change in temporal lobe and total oedema volumes in HSV encephalitis and suggests a potential resolution of swelling in response to corticosteroid therapy. These techniques could be used as part of a randomized control trial to investigate the efficacy of corticosteroids for treating HSV encephalitis in conjunction with assessing clinical outcomes and could be of potential value in helping to predict the clinical outcomes of patients with HSV encephalitis

Review on cephalopod resources, biology and stock assessment in Indian seas

Cephalopods are fished from the seas around India from very early times and at present contribute one of the most important exploited marine fishery resources oj the country (between 4 and 5% of the all India production). The production, which remained at very low level up to the early seventies, has shown a remarkable increase crossing the 1,00,000 tonne mark in 1994. The taxonomy, biology and stock assessment of the various exploited species have been studied since the early seventies by the CMFRI. Studies indicate that uplo 1994 tlie exploitation has remained within rational limits in almost all maritime states. The recent rapid increase in production warrants close monitoring of this short-lived resource from the viewpoint of Judicious management

Structural identifiability of dynamic systems biology models

22 páginas, 5 figuras, 2 tablas.-- This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.A powerful way of gaining insight into biological systems is by creating a nonlinear differential equation model, which usually contains many unknown parameters. Such a model is called structurally identifiable if it is possible to determine the values of its parameters from measurements of the model outputs. Structural identifiability is a prerequisite for parameter estimation, and should be assessed before exploiting a model. However, this analysis is seldom performed due to the high computational cost involved in the necessary symbolic calculations, which quickly becomes prohibitive as the problem size increases. In this paper we show how to analyse the structural identifiability of a very general class of nonlinear models by extending methods originally developed for studying observability. We present results about models whose identifiability had not been previously determined, report unidentifiabilities that had not been found before, and show how to modify those unidentifiable models to make them identifiable. This method helps prevent problems caused by lack of identifiability analysis, which can compromise the success of tasks such as experiment design, parameter estimation, and model-based optimization. The procedure is called STRIKE-GOLDD (STRuctural Identifiability taKen as Extended-Generalized Observability with Lie Derivatives and Decomposition), and it is implemented in a MATLAB toolbox which is available as open source software. The broad applicability of this approach facilitates the analysis of the increasingly complex models used in systems biology and other areasAFV acknowledges funding from the Galician government (Xunta de Galiza, Consellería de Cultura, Educación e Ordenación Universitaria http://www.edu.xunta.es/portal/taxonomy/term/206) through the I2C postdoctoral program, fellowship ED481B2014/133-0. AB and AFV were partially supported by grant DPI2013-47100-C2-2-P from the Spanish Ministry of Economy and Competitiveness (MINECO). AFV acknowledges additional funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 686282 (CanPathPro). AP was partially supported through EPSRC projects EP/M002454/1 and EP/J012041/1.Peer reviewe