Active vibration control (AVC) of a satellite boom structure using optimally positioned stacked piezoelectric actuators

In this paper, results for active vibration control predicted from experimental measurements on a lightweight structure are compared with purely computational predictions. The structure studied is a 4.5m long satellite boom consisting of 10 identical bays with equilateral triangular cross sections. First, the results from a Fortran code that is based on a receptance analysis are validated against the experimental forced response of the boom structure. Exhaustive searches are then carried out to find the optimum positions for one and two actuators. Finally, a genetic algorithm is employed to find high-quality positions for three actuators on the structure that will achieve the greatest reductions in vibration transmission. Having found these actuator positions, experiments are then carried out to verify the quality of the theoretical predictions. It was found that the attenuation achievable in practice for one, two and three actuators were, respectively, 15.1, 26.1 and 33.5 dB

Systematic Review of Supported Housing Literature 1993 – 2008

Supported housing for individuals with severe mental illness strives to provide the services necessary to place and keep individuals in independent housing that is integrated into the community and in which the consumer has choice and control over his or her services and supports. Supported housing can be contrasted to an earlier model called the “linear residential approach” in which individuals are moved from the most restrictive settings (e.g., inpatient settings) through a series of more independent settings (e.g., group homes, supervised apartments) and then finally to independent housing. This approach has been criticized as punishing the client due to frequent moves, and as being less likely to result in independent housing. In the supported housing model (Anthony & Blanch, 1988) consumers have choice and control over their living environment, their treatment, and supports (e.g., case management, mental health and substance abuse services). Supports are flexible and faded in and out depending on needs. Results of this systematic review of supported housing suggest that there are several well-controlled studies of supported housing and several studies conducted with less rigorous designs. Overall, our synthesis suggests that supported housing can improve the living situation of individuals who are psychiatrically disabled, homeless and with substance abuse problems. Results show that supported housing can help people stay in apartments or homes up to about 80% of the time over an extended period. These results are contrary to concerns expressed by proponents of the linear residential model and housing models that espoused more restrictive environments. Results also show that housing subsidies or vouchers are helpful in getting and keeping individuals housed. Housing services appear to be cost effective and to reduce the costs of other social and clinical services. In order to be most effective, intensive case management services (rather than traditional case management) are needed and will generally lead to better housing outcomes. Having access to affordable housing and having a service system that is well-integrated is also important. Providing a person with supported housing reduces the likelihood that they will be re-hospitalized, although supported housing does not always lead to reduced psychiatric symptoms. Supported housing can improve clients’ quality of life and satisfaction with their living situation. Providing supported housing options that are of decent quality is important in order to keep people housed and satisfied with their housing. In addition, rapid entry into housing, with the provision of choices is critical. Program and clinical supports may be able to mitigate the social isolation that has sometimes been associated with supported housing.National Institute on Disability and Rehabilitation Research, Grant # (H133A050006

The impact of internal and external factors on human rights conditions in Xinjiang, China

In 1949, the Chinese Communist Party (CCP) took control of Xinjiang from the Koumintang (KMT) and declared that Xinjiang was to be an autonomous region in 1955. However, major decisions were still made by the CCP led by the Han Chinese and not the Uyghurs from Xinjiang. The CCP implemented aggressive assimilation policies in the 1960s especially during the Cultural Revolution during which the Uyghurs were subjected to serious abuses. In 1978, Deng Xiaoping took over the leadership of China after the demise of Mao Zedong. It brought about dramatic changes in the human rights situation in China. These included freedom for the Uyghurs to practice their religion, culture and language. Hence, there was an improvement in human rights in Xinjiang. However, in the late 1990s the CCP reverted to harsh policies once again. This study examines the internal and external factors that have influenced China's policies on the human rights condition in Xinjiang. The aim of this study is to analyse the changes in the human rights condition in Xinjiang under the different administrations and the factors that have caused the changes

Correction-to-scaling exponents for two-dimensional self-avoiding walks

We study the correction-to-scaling exponents for the two-dimensional self-avoiding walk, using a combination of series-extrapolation and Monte Carlo methods. We enumerate all self-avoiding walks up to 59 steps on the square lattice, and up to 40 steps on the triangular lattice, measuring the mean-square end-to-end distance, the mean-square radius of gyration and the mean-square distance of a monomer from the endpoints. The complete endpoint distribution is also calculated for self-avoiding walks up to 32 steps (square) and up to 22 steps (triangular). We also generate self-avoiding walks on the square lattice by Monte Carlo, using the pivot algorithm, obtaining the mean-square radii to ~0.01% accuracy up to N = 4000. We give compelling evidence that the first non-analytic correction term for two-dimensional self-avoiding walks is Delta_1 = 3/2. We compute several moments of the endpoint distribution function, finding good agreement with the field-theoretic predictions. Finally, we study a particular invariant ratio that can be shown, by conformal-field-theory arguments, to vanish asymptotically, and we find the cancellation of the leading analytic correction.Comment: LaTeX 2.09, 56 pages. Version 2 adds a renormalization-group discussion near the end of Section 2.2, and makes many small improvements in the exposition. To be published in the Journal of Statistical Physic

'War is a snake that bites us with our own teeth' : reading war in Southern African literature from 1960 to 2002.

1960 marked the beginning of a profoundly violent and unstable period in southern Africa’s history. Central to the fundamental socio-political changes that took place in the region and many of its countries during this period were a number of wars, the last of which only ended in 2002. While the specific reasons for each of these wars were complex and varied, according to each country, the central roles these wars have played in the creation of the countries they affected – and the region as a whole – are evident to this day. It is, therefore, important to look at the position the writing of war holds in southern Africans’ attempts to represent, define and imagine southern Africa and its component countries during and after the experience of war. With this in mind, this study examines the manner in which the texts under scrutiny form a web of creative engagement in the context of a violent and unstable region. The aim of the work is to illustrate that the region’s writing of war can be seen to respond to both national and regional concerns and, in doing so, form a platform for an imagining of both nation and region. Methodologically, the research presented in this study is based on a close reading, through extensive contextualisation, of the selected primary texts with a view to understanding the similarities, commonalities and differences present in the region’s war writing. It is divided into six chapters which, aside from the Introduction and Conclusion, include readings of texts from Angola, Zimbabwe, South Africa and Mozambique. The study finds war to be central to the selected texts’ presentation of their imaginings of nation and, importantly, to the realisation, defence or dissolution of that imagined nation. Two factors are found to be key to these imaginings: the role of the moment in which the texts are written and the depiction of the role of the hero, in various forms, in the attainment or illustration of the nation. In terms of the study’s contentions relating to southern Africa as a region, the readings illustrate that war is central to the manner in which the region is also imagined by the texts’ authors. Additionally, the study reveals imaginings of region that change over time and thus map the shifting configurations of southern Africa formed as political allegiances between countries were transformed, or restructured, by the experience of war. In response to these findings, the study suggests that as a region, southern Africa owes much of its current configuration to the shared experience of war between 1960 and 2002. Paradoxically, therefore, war in southern Africa, as the primary texts show it to function, can be seen to have been socially developmental through the forced creation of a sense of region. This view has implications for the manner in which regions are viewed in other areas of the African continent because, by way of a similar use of war as a point of focus through which to read region in primary texts, the imaginings of other African regions, such as that created by wars in Somalia and Sudan, can be conceptualised and configured

Active vibration control (AVC) of a satellite boom structure using optimally positioned stacked piezoelectric actuators

In this paper, results for active vibration control predicted from experimental measurements on a lightweight structure are compared with purely computational predictions. The structure studied is a 4.5m long satellite boom consisting of 10 identical bays with equilateral triangular cross sections. First, the results from a Fortran code that is based on a receptance analysis are validated against the experimental forced response of the boom structure. Exhaustive searches are then carried out to find the optimum positions for one and two actuators. Finally, a genetic algorithm is employed to find high-quality positions for three actuators on the structure that will achieve the greatest reductions in vibration transmission. Having found these actuator positions, experiments are then carried out to verify the quality of the theoretical predictions. It was found that the attenuation achievable in practice for one, two and three actuators were, respectively, 15.1, 26.1 and 33.5 dB

The diffusion of IP telephony and vendors' commercialisation strategies

This is a post-peer-review, pre-copyedit version of an article published in the Journal of Information Technology. The definitive publisher-authenticated version is available at the link below.The Internet telephony (IP telephony) has been presented as a technology that can replace existing fixed-line services and disrupt the telecommunications industry by offering new low-priced services. This study investigates the diffusion of IP telephony in Denmark by focusing on vendors’ commercialisation strategies. The theory of disruptive innovation is introduced to investigate vendors’ perceptions about IP telephony and explore their strategies that affect the diffusion process in the residential market. The analysis is based on interview data collected from the key market players. The study's findings suggest that IP telephony is treated as a sustaining innovation that goes beyond the typical voice transmission and enables provision of advanced services such as video telephony