Passive damping concepts for slender columns in space structures

Research into the identification of potential passive damping concepts for use in very slender structural members was continued. The following damping concepts are under investigation: mass-string dampers; bright zinc chain; polyethylene tubing; external viscoelastic tape; brushes for electrostatic and frictional damping; suspended chambers with oil and discs; and hybrid concepts. Each of these concepts are briefly discussed

Changing Scottish education policy definitions of what it means to be a teacher: fit for a diverse system?

As countries seek to secure their economic future, education has become increasingly central to socioeconomic strategy in the United Kingdom and beyond. As a result, there is increased governmental expectation and scrutiny of the learning outcomes achieved by pupils. Following from this, teaching quality has become a significant focus in a number of countries. As part of the quality agenda, career-long professional learning has become a major policy theme from which a range of approaches has been implemented in Scotland: increased entry qualifications, the development of professional standards, and emphasis on the ongoing professional development of teachers. Within these approaches can be identified a reconceptualisation of what it means to be a teacher. While there is some expression of values related to social justice, equality and inclusion in education policy, the actions to implement policy tend to centre on instrumental approaches to career-long development. The idea of 'career-long teacher education' is underpinned by an assumption of a stable and readily accepted understanding of what it means to be a teacher. However, as expectations of schools have intensified, education policy indicates significant changes in the construction of the ‘effective’ teacher within an overall reconstruction of the nature and trajectory of the teaching career. This paper draws from a comparative policy study project and traces the evolving and competing ideas of what it means to be a teacher evident in recent key reviews (McCrone 2000; Donaldson, 2010; McCormac, 2011). It pays particular attention to how these ideas have been translated into expectations for initial teacher education and beyond in the form of the Standards for Registration (GTCS, 2012) and the Standard for Career-Long Professional Learning (GTCS, 2012). The paper considers the implications of the policy and the standards for the construction of teacher identity in both an increasingly globalised educational policy context and a more diverse Scottish society. It sets out for discussion the question of whether or not policy definitions of what it means to be a teacher in Scotland today are fit for a diverse, globalised and inclusive education system

Passive damping concepts for free and forced member and grillage vibration

The performance of potential passive damping concepts is investigted for a long tubular aluminum alloy member, and a two-bar grillage structure. The members are restrained partially at the ends and are of the type being considered by NASA for possible use in the construction of a future space station. Four different passive damping concepts are studied and include nylon brush, wool swab, copper brush, and silly putty in chamber dampers. Both free and forced vibration tests are conducted. It is found that the silly putty in chamber damper concept provides considerably greater passive damping as compared to that of the other three concepts. For the grillage natural vibration, a five wool swab damper configuration provides greater damping than the five silly putty dampers in chamber configuration. Due to the constrained motion imposed by the vibrator used in the tests, the effectiveness of the passive dampers could not be adequately evaluated for the individual member. However, it is found that for the grillage under forced vibration, the five silly putty dampers in chamber damper configuration provides very effective passive damping although only at and around the resonant frequency. At resonance, these dampers provide a 51 percent reduction in the dynamic magnification factor for this case

Estimating Import-Demand Function in ARDL Framework: The Case of Pakistan

We develop a structural econometric model of import demand for Pakistan, with binding foreign exchange constraint. ARDL and DOLS techniques are used to estimate the log-run coefficients of price and income elasticities. The empirical results from ARDL bound testing approach and Johansen’s method for cointegration show strong evidence of the existence of a long-run stable relationship among the variables included in the import demand model. The price and income elasticity estimates have correct signs and are statistically significant. The coefficient of scarcity premium, as it appeared statistically significant with correct sign, confirms the presence of a binding foreign exchange constraint on aggregate import demand, particularly before the period of trade liberalization.Import Demand; Foreign Exchange Constraint; ARDL; DOLS; Pakistan

Dynamic Relationship between Income and Consumption: A Time Series Analysis of Spain

This study examined the household and government consumption with income separately both in short and long run.The data is collected from the WDI from 1960 to 2010 of spain. Analysis is  done by using the co integration technique and error correction model. The results of the study demonstrate that household consumption is more than that of income in short run but in long run with the adjustment rate of 7% the consumption is less than income. In contrast ,the expenditures of government and consumption is more than that of its income in long run and vice versa. The reason for the more expenditures in long run is due to the debt financing. Keywords: Income, Consumption, Co integration, Error correction model, Spai

Two-Dimensional Sequential and Concurrent Finite Element Analysis of Unstiffened and Stiffened Aluminum and Composite Panels with Hole

The results of a detailed investigation of the distribution of stresses in aluminum and composite panels subjected to uniform end shortening are presented. The focus problem is a rectangular panel with two longitudinal stiffeners, and an inner stiffener discontinuous at a central hole in the panel. The influence of the stiffeners on the stresses is evaluated through a two-dimensional global finite element analysis in the absence or presence of the hole. Contrary to the physical feel, it is found that the maximum stresses from the glocal analysis for both stiffened aluminum and composite panels are greater than the corresponding stresses for the unstiffened panels. The inner discontinuous stiffener causes a greater increase in stresses than the reduction provided by the two outer stiffeners. A detailed layer-by-layer study of stresses around the hole is also presented for both unstiffened and stiffened composite panels. A parallel equation solver is used for the global system of equations since the computational time is far less than that using a sequential scheme. A parallel Choleski method with up to 16 processors is used on Flex/32 Multicomputer at NASA Langley Research Center. The parallel computing results are summarized and include the computational times, speedups, bandwidths, and their inter-relationships for the panel problems. It is found that the computational time for the Choleski method decreases with a decrease in bandwidth, and better speedups result as the bandwidth increases

Experimental and theoretical investigation of passive damping concepts for member forced and free vibration

Potential passive damping concepts for use in space structures are identified. The effectiveness of copper brush, wool swab, and silly putty in chamber dampers is investigated through natural vibration tests on a tubular aluminum member. The member ends have zero translation and possess partial rotational restraints. The silly putty in chamber dampers provide the maximum passive damping efficiency. Forced vibration tests are then conducted with one, two, and three damper chambers containing silly putty. Owing to the limitation of the vibrator used, the performance of these dampers could not be evaluated experimentally until the forcing function was disengaged. Nevertheless, their performance is evaluated through a forced dynamic finite element analysis conducted as a part of this investigation. The theoretical results based on experimentally obtained damping ratios indicate that the passive dampers are considerably more effective under member natural vibration than during forced vibration. Also, the maximum damping under forced vibration occurs at or near resonance

Capacity of local communities in pre and post disasters situation in coastal area of Pakistan

The present study attempted to assess the vulnerability of coastal areas of Pakistan that cashed in one's chips in the monsoon flood, 2010. This assessment helps to recognize the vulnerability of local people of coastal communities for planning better developmental work. The study conducted through field work in two districts “Thatta and Badin” of coastal area of Sindh Province of Pakistan. Multistage cluster sampling technique has used to select the sample size of 360 households from the area. Data was collected through well-structured questionnaire. Most of population in the study area is illiterate i.e. about 61% of population. This is not only due to lack of awareness and lack of passion to seek education, but, government also ignores these areas in the provision of educational facilities. Considering the disaster vulnerability of coastal areas, these health facilities are very few and it leads to make them more vulnerable towards various diseases caused by frequent disasters. Depending on the disaster vulnerability of the target area, disaster management arrangement had analyzed through the availability of emergency camp along with its distance from the villages. Vulnerability of coastal communities assessed using various indicators and in the end suggestions and recommendations put forward in the light of local vulnerability to have minimum loss in upcoming disasters.Disaster, Disaster Management, Vulnerability, Hazards, Global Warming, Rehabilitation, Awareness, Local Community

Higher-Order Effects in Biaxial Flexure of GFRP I-Section Beams

A theoretical study of Glass Fiber Reinforced Polymer (GFRP) beams subjected to biaxial bending moments is presented with a focus on the influence of higher-order effects on maximum normal stresses. It is shown that the biaxial bending type of loading causes a dramatic increase in the maximum normal stress for a GFRP beam when induced torsional effects are included. The study demonstrates that the traditional first-order theory can grossly underestimate the maximum normal stress in a GFRP beam. Based on the numerical results presented using a higher-order theory which also accounts for induced warping normal stresses, the maximum normal stress is found to be about two to three times larger than that determined using the first-order theory