On the wake of a Darrieus turbine

The theory and experimental measurements on the aerodynamic decay of a wake from high performance vertical axis wind turbine are discussed. In the initial experimental study, the wake downstream of a model Darrieus rotor, 28 cm diameter and a height of 45.5 cm, was measured in a Boundary Layer Wind Tunnel. The wind turbine was run at the design tip speed ratio of 5.5. It was found that the wake decayed at a slower rate with distance downstream of the turbine, than a wake from a screen with similar troposkein shape and drag force characteristics as the Darrieus rotor. The initial wind tunnel results indicated that the vertical axis wind turbines should be spaced at least forty diameters apart to avoid mutual power depreciation greater than ten per cent

Supersymmetry Relations Between Contributions To One-Loop Gauge Boson Amplitudes

We apply ideas motivated by string theory to improve the calculational efficiency of one-loop weak interaction processes with massive external gauge bosons. In certain cases ``supersymmetry'' relations between diagrams with a fermion loop and with a gauge boson loop hold. This is explicitly illustrated for a particular one-loop standard model process with four-external gauge bosons. The supersymmetry relations can be used to provide further significant improvements in calculational efficiency.Comment: 21 pages of plain TeX + 5 PostScript figures (compressed and uuencoded), UCLA/93/TEP/36 and DTP/93/8

Equilibrium configurations of two charged masses in General Relativity

An asymptotically flat static solution of Einstein-Maxwell equations which describes the field of two non-extreme Reissner - Nordstr\"om sources in equilibrium is presented. It is expressed in terms of physical parameters of the sources (their masses, charges and separating distance). Very simple analytical forms were found for the solution as well as for the equilibrium condition which guarantees the absence of any struts on the symmetry axis. This condition shows that the equilibrium is not possible for two black holes or for two naked singularities. However, in the case when one of the sources is a black hole and another one is a naked singularity, the equilibrium is possible at some distance separating the sources. It is interesting that for appropriately chosen parameters even a Schwarzschild black hole together with a naked singularity can be "suspended" freely in the superposition of their fields.Comment: 4 pages; accepted for publication in Phys. Rev.

Barriers which preclude the formation of strong, comprehensive wildfire mitigation plans and strategies in Ontario: a knowledge gap analysis

As occurrences of wildland-urban interface (WUI) wildfires become more frequent throughout Ontario, there has been an increasing need for mitigative approaches towards managing wildfire on landscapes, especially where human settlement has taken place. Since the provincial government and many communities based in Ontario’s boreal forest have not yet implemented mitigative actions against wildfire risk, this study will explore which factors act as barriers to the formation of a comprehensive wildfire mitigation strategy in Ontario. This literature review will analyse factors such as gaps in knowledge in fuel management techniques, social barriers, economic barriers, and policy barriers, which prevent the formation of a wildfire mitigation program in Ontario. Findings from the literature review reveal that the following points act as the main factors which prevent the formation of effective mitigation strategies in Ontario: (1) there is a distinct lack in research regarding fire behaviour in fuel treatments specific to Ontario’s forest types; (2) current forest management policies in Ontario are not conductive to wildfire mitigation; (3) there is an absence of funding and workforce for mitigation planning and implementation; and (4) there is a general lack in social and political understanding and support for community wildfire resiliency projects

Determining the Distribution of the Dowel Bearing Strength of Bambusa bluemana Connections

Bamboo has long been utilized as a structural element, especially in low-rise structures. However, the dowel bearing strength that is used to connect structural bamboo elements has not been fully established. Studying bamboo connections is significant since it affects the structure\u27s stability. In this study, the dowel bearing strength of a proposed bamboo connection is established through experimental tests (ASTM D5764). The species used in the tests is Bambusa blumeana with the following node presence: none, bottom, middle, and top. The dowel (rebar) diameters used are 3/8” and 1/2 , which is where the compressive load is applied until ultimate failure is reached. The results show that a top node placement with a 1/2” dowel (rebar) diameter has the highest failure load of 25.1 kN. Furthermore, the maximum loads can be modeled as a lognormal distribution. The findings contribute to a better understanding of the dowel bearing strength of bamboo connections considering different nodal positions and dowel diameters. The paper also proposes a lognormal distribution of the maximum strength

Physics with antihydrogen

Performing measurements of the properties of antihydrogen, the bound state of an antiproton and a positron, and comparing the results with those for ordinary hydrogen, has long been seen as a route to test some of the fundamental principles of physics. There has been much experimental progress in this direction in recent years, and antihydrogen is now routinely created and trapped and a range of exciting measurements probing the foundations of modern physics are planned or underway. In this contribution we review the techniques developed to facilitate the capture and manipulation of positrons and antiprotons, along with procedures to bring them together to create antihydrogen. Once formed, the antihydrogen has been detected by its destruction via annihilation or field ionization, and aspects of the methodologies involved are summarized. Magnetic minimum neutral atom traps have been employed to allow some of the antihydrogen created to be held for considerable periods. We describe such devices, and their implementation, along with the cusp magnetic trap used to produce the first evidence for a low-energy beam of antihydrogen. The experiments performed to date on antihydrogen are discussed, including the first observation of a resonant quantum transition and the analyses that have yielded a limit on the electrical neutrality of the anti-atom and placed crude bounds on its gravitational behaviour. Our review concludes with an outlook, including the new ELENA extension to the antiproton decelerator facility at CERN, together with summaries of how we envisage the major threads of antihydrogen physics will progress in the coming years

APLIKASI IRIGASI TETES UNTUK OPTIMASI LAHAN KERING DI MUSIM KEMARAU DENGAN BUDIDAYA HORTIKULTURA SEMUSIM PADA KELOMPOK TANI ANUGERAH TRIBUANA DESA MATA AIR, KECAMATAN KUPANG TENGAH, KABUPATEN KUPANG

Tujuan kegiatan pengabdian kepada masyarakat ini adalah: 1) Mengadopsi teknologi irigasi tetes sederhana yang dapat dilakukan oleh petani untuk membudidayakan berbagai jenis tanaman hortikultura dengan memanfaatkan pekarangan yang ada maupun dikembangkan lebih luas pada lahan sawah yang masih ada sedikit air/kelembaban pada musim kemarau. 2) Memberikan pengetahuan kepada para petani pembudidaya  tentang pembuatan pupuk organik dan pestisida nabati dari limbah rumah tangga/limbah pertanian melalui praktek secara langsung. 3) Memberikan pengetahuan untuk penanganan hama dan patogen tanaman hortikultura. Hasil kegiatan ini adalah dengan kehadiran dalam program kemitraaan masyarakat yang telah dilakukan, petani sangat antusias yang ditunjukan dengan berdiskusi mengenai bagaimana budidaya hortikultura semusim dengan penerapan teknologi irigasi tetes yang tepat dan efektif untuk menunjang keterbatasan air di lahan kering, kombinasi pemupukan organik dan anorganik serta pengendalian organisme pengganggu tanaman di lahan kering. Materi yang disajikan mengenai budidaya hortikultura semusim serta aplikasi teknologi irigasi tetes di lahan kering sangat antusias direspons oleh peserta program kemitraan masyarakat yang memberikan pertanyaan dan respons balik, terutama bagaimana penerapan teknologi irigasi tetes dilapangan dan model pemanfatannya

Longevity, body dimension and reproductive mode drive differences in aquatic versus terrestrial life-history strategies

1. Aquatic and terrestrial environments display stark differences in key environmental factors and phylogenetic composition but their consequences for the evolution of species' life-history strategies remain poorly understood. 2. Here, we examine whether and how life-history strategies vary between terrestrial and aquatic species. We use demographic information for 685 terrestrial and 122 aquatic animal and plant species to estimate key life-history traits. We then use phylogenetically corrected least squares regression to explore potential differences in trade-offs between life-history traits between both environments. We contrast life-history strategies of aquatic versus terrestrial species in a principal component analysis while accounting for body dimensions and phylogenetic relationships. 3. Our results show that the same trade-offs structure terrestrial and aquatic life histories, resulting in two dominant axes of variation that describe species' pace of life and reproductive strategies. Terrestrial plants display a large diversity of strategies, including the longest-lived species in this study. Aquatic animals exhibit higher reproductive frequency than terrestrial animals. When correcting for body size, mobile and sessile terrestrial organisms show slower paces of life than aquatic ones. 4. Aquatic and terrestrial species are ruled by the same life-history trade-offs, but have evolved different strategies, likely due to distinct environmental selective pressures. Such contrasting life-history strategies have important consequences for the conservation and management of aquatic and terrestrial species

Role of Social Networks in Adoption of Technology and Empowerment of Women: Sociological Evidences from Village-level Studies

There is abundant literature and information produced regarding social networks and the specific roles that women play in these networks and benefits they receive through them. However, much is left to be explored and understood on the role of social networks in increasing women's and men's access to resources and opportunities, and to establish means to map and measure them and how they are gendered. Another important step is to identify how social networks empower women, speci fically in terms of increasing their bargaining power. Studies suggest that men and women build and utilize social networks differently, and because the multiple roles that women and women's social networks play it is important to recognize and facilitate networks that can increase household access to necessary productive resources (Flora 2001). Increased participation by women in social networks can increase access to resources such as information about employment opportunities or income during economic crisis