Optical analysis of parabolic dish concentrators for solar dynamic power systems in space

An optical analysis of a parabolic solar collection system operating in Earth orbit was performed using ray tracing techniques. The analysis included the effects of: (1) solar limb darkening, (2) parametric variation of mirror surface error, (3) parametric variation of mirror rim angle, and (4) parametric variation of alignment and pointing error. This ray tracing technique used numerical integration to combine the effects of rays emanating from different parts of the sun at different intensities with the effects of normally distributed mirror-surface errors to compute the angular intensity distribution of rays leaving the mirror surface. A second numerical integration was then performed over the surface of the parabolic mirror to compute the radial distribution of brightness at the mirror focus. Major results of the analysis included: (1) solar energy can be collected at high temperatures with high efficiency, (2) higher absorber temperatures can be achieved at lower efficiencies, or higher efficiencies can be achieved at lower temperatures, and (3) collection efficiency is near its maximum level across a broad plateau of rim angles from 40 deg to 70 deg

Experimental investigation of reactor-loop transients during SNAP-8 power conversion system startup

Experimental investigation of reactor loop transients during SNAP 8 power conversion system startu

Selecting SUDS in the Valencia Region of Spain

This paper reports on a study of the implementation of sustainable urban drainage systems (SUDS) in two Spanish towns (Xàtiva and Benaguasil) as part of the EU LIFE+ Project AQUAVAL, which has been conceived to introduce examples of sustainable drainage to the Valencia Region of Spain. Six sites in a range of common urban spaces and land uses are selected and appropriate SUDS techniques proposed by means of a decision-support process. This primarily consisted of the systematic application of key selection criteria through matrices and scores, followed by a brief sustainability analysis. Stakeholders’ preferences and opinions as well as educational and social opportunities are highly considered throughout the process. General monitoring requirements and major limitations in using the methodology are outlined, stressing the need for improvement of four main aspects: local data regarding SUDS performance, detail of the sustainability analysis, support through comprehensive modelling tools, and level of stakeholder engagement. The importance of creating showcases for SUDS in Mediterranean Regions, thus adapting key selection criteria as to foster sustainable drainage understanding and expertise is highlighted

Digital computer study of nuclear reactor thermal transients during startup of 60-kWe Brayton power conversion system

A digital computer study was made of reactor thermal transients during startup of the Brayton power conversion loop of a 60-kWe reactor Brayton power system. A startup procedure requiring the least Brayton system complication was tried first; this procedure caused violations of design limits on key reactor variables. Several modifications of this procedure were then found which caused no design limit violations. These modifications involved: (1) using a slower rate of increase in gas flow; (2) increasing the initial reactor power level to make the reactor respond faster; and (3) appropriate reactor control drum manipulation during the startup transient

A water vision for Johnstone

The Water Vision is based on ideas from The Netherlands which promote communication with the public on key water related issues in a local authority area. A Water Vision for Johnstone was developed in Renfrewshire, Scotland where serious flooding has occurred in the past and new, predominantly non-structural approaches to surface water management were demanded. The paper outlines the development of a ‘Water Vision for Johnstone’ which became a key outcome of the Interreg III B project ‘Urban Water’.The Water Toets (Assessments) are statutory procedures in the Netherlands which come into play from the concept stage of developments onwards to full implementation. They are undertaken jointly on behalf of the spatial planning authority and the water authorities to evaluate the impact of development on the water network. In contrast, the Water Vision is a less well-defined process to identify community needs and aspirations but in many areas the vision is essential to support the Water Toets. The Water Vision is initiated by planning officers from the municipalities asking very basic questions of their communities about what they required of the water network. It was felt that adopting such a proactive approach where virtually any question about water bodies and drainage infrastructure could be asked, would not be practicable in the UK and it was decided to assemble information about water issues in the area, the agencies involved and potential ways forward, before approaching the public.Johnstone was selected as a test area as it was felt that this locality included many of the water related problems that can be found throughout Renfrewshire. Key water issues were identified and a range of possible solutions provided. Problems, solutions and organisations responsible for different aspects of the water network are described in the document, using images and plans to facilitate the public awareness. Normally the man in the street would not be expected to be as familiar with the nature of water-related problems as the general public in the Netherlands. The Water Vision is yet to go to public consultation as it is currently primarily a planning tool in which council processes are embedded. However, it is planned that workshops including all key stakeholders involved in water management will be held. Those bodies currently responsible for water management will then be encouraged to discuss the various options and opportunities available in a creative and integrated manner. By working together as a team in addressing water related issues it will be possible to develop a vision for the future that better assists the public in moving forward together

Session:management of drainage near source – disconnection/minimise surface water entering public drainage

Many combined sewer networks are currently constrained due to lack of capacity. Surface water entering the network may have an impact on the local environment by causing additional spills from Combined Sewer Overflows (CSOs) and flooding events. With the increasing number of developments taking place in Scotland, more and more demands are being placed upon the existing wastewater assets and infrastructure of the drainage utility, Scottish Water. The principal way of preventing these CSO spills/flooding event s is to reduce the number of surface water connections to the combined sewer network and promote more surface water discharges to nearby watercourses.The problem is being addressed by examining all development applications as they are considered by a drainage planning officer in the water authority. The research reported in this paper is investigating the conditions under which it is reasonable and practical for Scottish Water to accept surface water flows into its combined sewer network . This paper presents a summary of the initial findings of the research to date by examining a sample of the sites examined. The objective of the work is to develop a methodology to support a rigorous stance on the acceptance of surface water flows into the combined sewer network. The results have not as yet been obtained

Any Time? Any Place? The impact on student learning of an on-line learning environment.

Original paper can be found at: http://www.actapress.com/Content_of_Proceeding.aspx?proceedingID=292#pages Copyright ACTA Press [Full text of this paper is not available in the UHRA]An increasing number of HE institutions are adopting virtual and managed learning environments (VLEs and MLEs), which offer flexible access to on-line learning materials all day and every day. There are multiple claims about e-learning enhancing learning and teaching (eg. [1] Britain and Liber, 1999; [2]Conole, 2002; [4]Allen, 2003; [5]Littlejohn and Higginson, 2003) such as supporting active learning, facilitative rather than didactic teaching and increased student motivation but these are not pre determined outcomes. Much depends on how lecturers use the available technology and how students respond to that use. This paper reports on a research project which has evaluated the students' own experience of on-line learning at the University of Hertfordshire. Using its own institution-wide MLE (StudyNet) academic staff at the university have been able to offer students on-line access to their study material from September 2001. Activities available for students using StudyNet include participating in discussion forums, using formative assessment materials and accessing journal articles as well as viewing and downloading courseware for each of their courses. Students were invited to participate in a questionnaire and focus groups to identify the characteristics of the on-line learning environment which benefited their learning

Experimental investigation of reactor-loop transients during startup of a simulated SNAP-8 system

Primary loop transients during startup of Rankine cycle space power system in SNAP 8 simulato

Concentration of off-axis radiation by solar concentrators for space power

Off-axis radiation is radiation from any direction not parallel to the axis of the solar concentrator. It will be reflected to regions other than the focus of the parabolic concentrator and possibly concentrated there. Four types of off-axis radiation are discussed. These are: (1) small off-axis angles during walk-off; (2) large off-axis angles; (3) an extended off-axis source such as Earth albedo; and (4) miscellaneous off-axis sources including radio frequency sources and local point sources. A previous analytical study used a computer code named PIXEL to predict concentration of off-axis radiation and a previous experimental study used an 11-m diameter multifaceted dish concentrator to validate the PIXEL analysis. The PIXEL code was limited in that it represented concentration by an ideal parabolic reflector of light from a point source. Another code named OFFSET has been developed to represent the solar concentrator being developed for Space Station Freedom. It is a detailed, ray tracing model which represents 50 ray originating points on the Sun and reflections from 10 points on each of the 456 concentrator facets. Results of this code are generally similar to the PIXEL results although there are small differences due to the more detailed representations of the Sun and concentrator that were used in the OFFSET code