Design of a reusable kinetic energy absorber for an astronaut safety tether to be used during extravehicular activities on the Space Station

The goal of this project is to design a reusable safety device for a waist tether which will absorb the kinetic energy of an astronaut drifting away from the Space Station. The safety device must limit the tension of the tether line in order to prevent damage to the astronaut's space suit or to the structure of the spacecraft. The tether currently used on shuttle missions must be replaced after the safety feature has been developed. A reusable tether for the Space Station would eliminate the need for replacement tethers, conserving space and mass. This report presents background information, scope and limitations, methods of research and development, alternative designs, a final design solution and its evaluation, and recommendations for further work

Construct Validity of Dimensions of Adaptive Behavior: A Multitrait-Multimethod Evaluation.

The construct validity of four dimensions of adaptive and maladaptive behavior was investigated using the multitrait-multimethod matrix procedure of Campbell and Fiske (1959). Measures off our traits cognitive competence, social competence, social maladaption, and personal maladaption were obtained on a sample of 157 persons with moderate, severe, or profound mental retardation using each of three methods of measurement-standardized assessment instrument, day shift staff ratings, and evening shift staff ratings. Applying the Campbell and Fiske rules of thumb and recently proposed structural equation modeling techniques to the data demonstrated strong convergent validity, clear discriminant validity, and only moderate levels of method variance in the observed measures. implications of the results for the assessment of adaptive behavior and its dimensional structure were discussed

An Integro-Differential Equation of the Fractional Form: Cauchy Problem and Solution

Producción CientíficaWe solve the Cauchy problem defined by the fractional partial differential equation [∂tt − κD]u = 0, with D the pseudo-differential Riesz operator of first order, and certain initial conditions. The solution of the Cauchy problem resulting from the substitution of the Gaussian pulse u(x, 0) by the Dirac delta distribution ϕ(x) = μδ(x) is obtained as corollary.MINECO grant MTM2014-57129-C2-1-P

Geometric Quantization on the Super-Disc

In this article we discuss the geometric quantization on a certain type of infinite dimensional super-disc. Such systems are quite natural when we analyze coupled bosons and fermions. The large-N limit of a system like that corresponds to a certain super-homogeneous space. First, we define an example of a super-homogeneous manifold: a super-disc. We show that it has a natural symplectic form, it can be used to introduce classical dynamics once a Hamiltonian is chosen. Existence of moment maps provide a Poisson realization of the underlying symmetry super-group. These are the natural operators to quantize via methods of geometric quantization, and we show that this can be done.Comment: 17 pages, Latex file. Subject: Mathematical physics, geometric quantizatio

Toeplitz operators on symplectic manifolds

We study the Berezin-Toeplitz quantization on symplectic manifolds making use of the full off-diagonal asymptotic expansion of the Bergman kernel. We give also a characterization of Toeplitz operators in terms of their asymptotic expansion. The semi-classical limit properties of the Berezin-Toeplitz quantization for non-compact manifolds and orbifolds are also established.Comment: 40 page

A Study of Challenges and Benefits of Lean Construction (LC) Principles in Omani Construction Industry

There are frequent failures in the project delivery in time and increasing the waste in Oman construction industry. Lean Construction (LC) principles which is lean thinking in design and construction process may be a possible solution. Hence, the paper is aimed on exploring the status of the LC practices and its impact on Omani Construction Industry (OCI). The paper presents barriers, potential benefits, and the measures of suitability and acceptability of LC principles. A quantitative research approach was adopted and research data was collected using an online questionnaire survey in Oman. The data was analysed and results are presented in tables and charts followed by critical discussions. The survey found that one-third of the construction professionals have a good awareness and half of then having a higher level awareness about LC practices. More than one third of the construction organisations are adopting LC principles with a high consensus on the suitability and acceptability, and they recognised that time commitment are necessary for the successful implementation and achieve benefits. The study concludes that the reduction in project delivery time and construction at site waste is the key advantage of implementing LC principles in design and construction stages in the Omani construction industry

Analyzing the Critical Risk Factors in Oil and Gas Pipelines Projects Regarding the Perceptions of the Stakeholders

Oil and Gas Pipeline (OGP) projects face a wide range of Risk Factors (RFs) at the design, construction and operational stages of the project particularly because of Third Party Disturbance (TPD) in the insecure environments. The lack of risk information and the root causes of pipelines’ failures are hindering the efforts of managing these risks. Therefore, this paper aims to analyze the existing risk factors and recommend an effective Risk Mitigation Methods (RMMs) based on a holistic approach from the prospect of stakeholders’ interest. An investigation was carried out to identify the critical RFs and existing RMMs in different circumstances to overcome the problem of the historical records about the RFs and RMMs. The findings of the literature review were used to design a questionnaire survey to analyze RFs and evaluate the “usability and effectiveness” of the RMMs. The RFs were ranked by using Risk Index (RI) method based on the probability and severity levels of each RF. The survey results revealed that sabotage and terrorism as part of TPD, corruption and insecure areas are the most critical RFs, whereas, anti-corrosion efforts, underground pipelines and technologically advanced risk monitoring systems are the most effective RMMs. These ranking are vary based on the occupation of the stakeholder in OGPs; like the planners and the researchers said corruption is the most critical RF, and the researchers said that the advance risk monitoring systems are the most effective RMM

Challenges and prospects of applying asset management principles to Highway maintenance: A case study of the UK

Past models and tools that support in the decision making process based on Asset Management Principles (AMP) are lacking in terms of the effective outcomes and transparency of the process in highway maintenance. There is also little research on how to align the decision areas when applying AMP and how to improve the inclusive effectiveness. Hence, the paper focuses on examining the challenges and prospects of applying AMP in a highway maintenance agency or department. An exploratory research method was used through an extensive review of literature and an industry survey. The findings from the literature and case study review were used to design a questionnaire and conduct the survey. The survey results revealed that the AMP are only being implemented ineffectively in maintaining highways, and a strong commitment is required to improve the asset management capability for effective use of the asset data. It is highly recommended that the Highway Agency should issue a guideline for implementing asset management policy and also encourage associate departments to achieve asset management maturity level 3 so that ISO55000 certification can be achieved. The study concludes that there is still substantial work needed within the asset management process, particularly in the highway maintenance before its effectiveness can be realised and measured

Tracer Advection in an Idealised River Bend with Groynes

This paper presents numerical simulations of particle advection in the bend of an open channel containing groynes, which is an idealised form of a shallow river bend in a wide river. The flow field is computed using a boundary-fitted solver of the non-orthogonal, curvilinear shallow water equations. The computational grid is generated by solving Poisson-type elliptic partial differential equations using an iterative multi-grid scheme for prescribed boundary coordinates. The shallow water equations are discretised with finite differences in space, and 4th order Runge-Kutta integration in time. Tracers introduced at specific initial locations have their trajectories computed using Lagrangian particle tracking. The numerical shallow flow model is verified by comparison to the analytical solution of fully developed flow in an open channel. The combined shallow flow and Lagrangian particle-tracking model is then used to simulate the advection of tracer particles in a rectangular channel containing a pair of parallel groynes, and tracer particles in a curved open channel containing groynes, of dimensions roughly equivalent to a Danube River bend