Solar thermal energy receiver

A plurality of heat pipes in a shell receive concentrated solar energy and transfer the energy to a heat activated system. To provide for even distribution of the energy despite uneven impingement of solar energy on the heat pipes, absence of solar energy at times, or failure of one or more of the heat pipes, energy storage means are disposed on the heat pipes which extend through a heat pipe thermal coupling means into the heat activated device. To enhance energy transfer to the heat activated device, the heat pipe coupling cavity means may be provided with extensions into the device. For use with a Stirling engine having passages for working gas, heat transfer members may be positioned to contact the gas and the heat pipes. The shell may be divided into sections by transverse walls. To prevent cavity working fluid from collecting in the extensions, a porous body is positioned in the cavity

Structure determination of new algal toxins using NMR methods

Shellfish are considered a delicacy by many consumers. In NZ, as in many overseas countries, there is a now thriv¬ing shellfish industry servicing both domestic and inter-national markets. Periodically shellfish accumulate harm¬ful levels of a variety of algal toxins, including domoic acid, yessotoxins, pectenotoxins and brevetoxins. When this occurs, regulatory authorities may impose harvesting closures which have a consequential economic impact on both farmers and staff employed to harvest and market shellfish products

A heat receiver design for solar dynamic space power systems

An advanced heat pipe receiver designed for a solar dynamic space power system is described. The power system consists of a solar concentrator, solar heat receiver, Stirling heat engine, linear alternator and waste heat radiator. The solar concentrator focuses the sun's energy into a heat receiver. The engine and alternator convert a portion of this energy to electric power and the remaining heat is rejected by a waste heat radiator. Primary liquid metal heat pipes transport heat energy to the Stirling engine. Thermal energy storage allows this power system to operate during the shade portion of an orbit. Lithium fluoride/calcium fluoride eutectic is the thermal energy storage material. Thermal energy storage canisters are attached to the midsection of each heat pipe. The primary heat pipes pass through a secondary vapor cavity heat pipe near the engine and receiver interface. The secondary vapor cavity heat pipe serves three important functions. First, it smooths out hot spots in the solar cavity and provides even distribution of heat to the engine. Second, the event of a heat pipe failure, the secondary heat pipe cavity can efficiently transfer heat from other operating primary heat pipes to the engine heat exchanger of the defunct heat pipe. Third, the secondary heat pipe vapor cavity reduces temperature drops caused by heat flow into the engine. This unique design provides a high level of reliability and performance

Two-stage reusable launch system utilizing a winged core vehicle and glideback boosters

A near-term technology launch system is described in which Space Shuttle main engines are used on a manned orbiter and also on twin strap-on unmanned boosters. The orbiter has a circular body and clipped delta wings. The twin strap-on boosters have a circular body and deployable oblique wings for a glideback recovery. The dry and gross weights of the system, capable of delivering 70klb of cargo to orbit, are compared with a similar system with hydrocarbon-fueled boosters and with the current Shuttle

Solar dynamic power for Earth orbital and lunar applications

Development of solar dynamic (SD) technologies for space over the past 25 years by NASA Lewis Research Center brought SD power to the point where it was selected in the design phase of Space Station Freedom Program as the power source for evolutionary growth. More recent studies showed that large cost savings are possible in establishing manufacturing processes at a Lunar Base if SD is considered as a power source. Technology efforts over the past 5 years have made possible lighter, more durable, SD components for these applications. A review of these efforts and respective benefits is presented

Health chatbots acceptability moderated by perceived stigma and severity: A cross-sectional survey

Background: Chatbots and virtual voice assistants are increasingly common in primary care without sufficient evidence for their feasibility and effectiveness. We aimed to assess how perceived stigma and severity of various health issues are associated with the acceptability for three sources of health information and consultation: an automated chatbot, a General Practitioner (GP), or a combination of both. Methods: Between May and June 2019, we conducted an online study, advertised via Facebook, for UK citizens. It was a factorial simulation experiment with three within-subject factors (perceived health issue stigma, severity, and consultation source) and six between-subject covariates. Acceptability rating for each consultation source was the dependant variable. A single mixed-model ANOVA was performed. Results: Amongst 237 participants (65% aged over 45 years old, 73% women), GP consultations were seen as most acceptable, followed by GP-chatbot service. Chatbots were seen least acceptable as a consultation source for severe health issues, while the acceptability was significantly higher for stigmatised health issues. No associations between participants’ characteristics and acceptability were found. Conclusions: Although healthcare professionals are perceived as the most desired sources of health information, chatbots may be useful for sensitive health issues in which disclosure of personal information is challenging. However, chatbots are less acceptable for health issues of higher severity and should not be recommended for use within that context. Policymakers and digital service designers need to recognise the limitations of health chatbots. Future research should establish a set of health topics most suitable for chatbot-led interventions and primary healthcare services

The Anisotropic and isotropic strength behavior of an illitic clay

The cause and the nature of anisotropy in a cohesive soil was investigated by direct shear and triaxial compression tests. Laboratory techniques and procedures used to prepare isotropic clay samples are given where consolidation was accomplished under hydrostatic pressure. Direct shear tests were performed on these specimens trimmed at different inclinations to the physical horizontal from the block samples. The ratio of undrained shear strengths in any direction to shear strength in the vertical direction was found to be equal to one, proving isotropy existed. Similar tests were performed on specimens trimmed from the same clay consolidated one-dimensionally. Results from these tests showed the shear strength ratio to be maximum for specimens trimmed at 90° to the horizontal plane. In this case, the aniso- tropic characteristics were directly attributed to the sample stress history. These samples indicated preferred particle orientation. Undrained triaxial compression tests were performed on both hydrostatic and one-dimensionally consolidated samples. Triaxial test results confirmed the results of the direct shear tests and more accurately defined the stress/strength parameters. The angle between the failure plane and the test specimens axis was essentially constant and the ratio between pore water pressure at failure and the mean consolidation stress remained a constant.For each maximum consolidation stress, pore pressure was isotropic, but in all cases was higher for hydrostatically prepared samples. The hydrostatic method of preparing isotropic test specimens was effective and produced reliable results