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

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

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

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

Medium-term performance and maintenance of SUDS:a case-study of Hopwood Park Motorway Service Area, UK

One of the main barriers to implementing SUDS is concern about performance and maintenance costs since there are few well-documented case-studies. This paper summarizes studies conducted between 2000 and 2008 of the performance and maintenance of four SUDS management trains constructed in 1999 at the Hopwood Park Motorway Service Area, central England. Assessments were made of the wildlife value and sedimentation in the SUDS ponds, the hydraulic performance of the coach park management train, water quality in all management trains, and soil/sediment composition in the grass filter strip, interceptor and ponds. Maintenance procedures and costs were also reviewed. Results demonstrate the benefits of a management train approach over individual SUDS units for flow attenuation, water treatment, spillage containment and maintenance. Peak flows, pond sediment depth and contaminant concentrations in sediment and water decreased through the coach park management train. Of the 2007 annual landscape budget of £15,000 for the whole site, the maintenance costs for SUDS only accounted for £2,500 compared to £4,000 for conventional drainage structures. Furthermore, since sediment has been attenuated in the management trains, the cost of sediment removal after the recommended period of three years was only £554 and, if the design is not compromised, less frequent removal will be required in future

Advanced secondary power system for transport aircraft

A concept for an advanced aircraft power system was identified that uses 20-kHz, 440-V, sin-wave power distribution. This system was integrated with an electrically powered flight control system and with other aircraft systems requiring secondary power. The resulting all-electric secondary power configuration reduced the empty weight of a modern 200-passenger, twin-engine transport by 10 percent and the mission fuel by 9 percent

The Riemann Hypothesis

This literature review provides a brief discussion of the Riemann Hypothesis, a conjecture regarding the location of the zeros on the Riemann zeta function. We also look at the implications of solving the hypothesis, and investigate historical attempts to solve the conjecture

Carriage rates, circulating serotypes and antibiotic resistance among Streptococcus pneumoniae in healthy infants in Yei, South Sudan

The carriage of Streptococcus pneumoniae, serotypes, antimicrobial susceptibility patterns and disease development are poorly understood in Yei. Availability of affordable antibiotics over the counter, lack of laboratory infrastructure and high rates of penicillin resistance have the potential to aggravate rates of childhood mortality associated with Streptococcus pneumoniae. There is an urgent need to strengthen microbiological and public health services