History of Stepped Channels and Spillways: a Rediscovery of the 'Wheel'

Recently, spillways with a stepped profile have regained interest and favor among design engineers to pass flood waters over the dams. The stepped geometry enhances the energy dissipation above the spillway and reduces the size of a downstream stilling basin. In this paper, the author shows that the technique of stepped channels has been developed since Antiquity. Spillways and irrigation channels with stepped profiles were developed by several civilisations around the Mediterranean sea and in America. The main characteristics of the stepped spillways along the ages suggest a regular evolution rather than a revolution. Present stepped spillways are designed to pass similar discharges as two hundred years ago

Design and Microwave-assisted Synthesis of 1,3,4-Oxadiazole Derivatives for Analgesic and Anti-inflammatory Activity

1,3,4-Oxadizoles form a biologically important group of compounds having activities like analgesic, anti-inflammatory, bactericidal, antifungal, anticonvulsant, psychotropic, plant growth regulating and mono amino oxidase inhibition. This research has focused on the incorporation of the oxadiazole moiety into isoniazid because of their versatile biological action, to get 2-aryl-5-(4-pyridyl)-1,3,4-oxadiazole to explore the possibilities of some altered biological action. 1,3,4-Oxadiazole derivatives were synthesized by microwave-assisted synthesis and screened for their analgesic, anti-inflammatory activities. The synthesized compounds were characterized by Melting point, Thin layer chromatographyInfra red, Nuclear magnetic resonance spectroscopy, etc. Almost all the synthesized compounds possessed good activity as compared to the standard

Environmental impact assessments of the Three Gorges Project in China: issues and interventions

The paper takes China's authoritative Environmental Impact Statement for the Yangzi (Yangtze) Three Gorges Project (TGP) in 1992 as a benchmark against which to evaluate emerging major environmental outcomes since the initial impoundment of the Three Gorges reservoir in 2003. The paper particularly examines five crucial environmental aspects and associated causal factors. The five domains include human resettlement and the carrying capacity of local environments (especially land), water quality, reservoir sedimentation and downstream riverbed erosion, soil erosion, and seismic activity and geological hazards. Lessons from the environmental impact assessments of the TGP are: (1) hydro project planning needs to take place at a broader scale, and a strategic environmental assessment at a broader scale is necessary in advance of individual environmental impact assessments; (2) national policy and planning adjustments need to react quickly to the impact changes of large projects; (3) long-term environmental monitoring systems and joint operations with other large projects in the upstream areas of a river basin should be established, and the cross-impacts of climate change on projects and possible impacts of projects on regional or local climate considered. © 2013 Elsevier B.V.Xibao Xu, Yan Tan, Guishan Yan

The Role of Trust in Public Attitudes toward Invasive Species Management on Guam: A Case Study

Public attitudes toward invasive alien species management and trust in managers’ ability to effectively manage non-native species can determine public support for conservation action. Guam has experienced widespread species loss and ecosystem transformation due to invasive species. Despite Guam’s long history with invasives and efforts to eradicate them, we know little about the sociological context of invasive species. Using focused group discussions, we explore public attitudes toward invasive species management. Respondents expressed support for management activities and a desire to participate directly in conservation actions. Participants also expressed frustration with government institutions and lack of confidence in managers’ abilities to control invasive species. Perceptions of managers’ trustworthiness, communication with managers, and positive personal experiences with managers were related to positive attitudes about management and support for existing initiatives

The simulation of urban-scale evacuation scenarios with application to the Swinley forest fire

Forest fires are an annual occurrence in many parts of the world forcing large-scale evacuation. The frequent and growing occurrence of these events makes it necessary to develop appropriate evacuation plans for areas that are susceptible to forest fires. The buildingEXODUS evacuation model has been extended to model large-scale urban evacuations by including the road network and open spaces (e.g. parks, green spaces and town squares) along with buildings. The evacuation simulation results have been coupled with the results of a forest fire spread model and applied to the Swinley forest fire which occurred in Berkshire, UK in May 2011. Four evacuation procedures differing in the routes taken by the pedestrians were evaluated providing key evacuation statistics such as time to reach the assembly location, the distance travelled, congestion experienced by the agents and the safety margins associated with using each evacuation route. A key finding of this work is the importance of formulating evacuation procedures that identifies the threatened population, provides timely evacuation notice, identifies appropriate routes that maintains a safe distance from the hazard front thereby maximising safety margins even at the cost of taking longer evacuation routes. Evacuation simulation offers a means of achieving these goals

Entry into New Niches: The Effects of Firm Age and the Expansion of Technological Capabilities on Innovative Output and Impact

We provide evidence that young firms systematically differ from older firms in their innovative output when they enter 'new to the firm' technological niches. We analyze data from 128 biotechnology firms since their inception and track these firms over time. Our analyses reveal that the organizational age at which the firm branches into new technological niches significantly influences its innovative activity. We refine the focus of the extant literature by separately examining the effects of branching on the quantity of innovative output and the impact that this output has on the technology domain. Subsequent to branching into new niches, we find that older firms have a higher quantity of output than their younger counterparts, whereas young firms tend to outpace their older rivals with higher impact. We discuss the implications of these findings for the literature on dynamic capabilities and entrepreneurship. © 2011 John Wiley & Sons, Ltd.link_to_subscribed_fulltex

The Chicago main drainage channel. A description of the machinery used and methods of work adopted in excavating the 28-mile drainage canal from Chicago to Lockport, Ill.

"Reprinted from Engineering News (Vols. XXXIII and XXXIV), with much additional matter.Mode of access: Internet