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It is indeed seldom that a specialised subject can be considered independently. Usually it is allied to and embodied in a systematic sequence of principles, and its field is generally an integral part of a reflection of some broader conception. This is especially true of this thesis, which is concerned with the climatic environmental influences on regional architecture. In the process of evolving the passive solar aspects, theoretical considerations yielded some interesting details and solutions. Examples studied showed a great variety of design principles. Thus as the material grew it suggested an entity -a theme itself. Cont/d.

with the development of a low-grade energy engine in the School of Mechanical Engineering at Cranfield, there began a venture towards utilizing the Sun's power to operate the engine via a thermodynamic cycle, in an Egyptian desert area, i. e latitude 3Q0N. The derived mechanical power is to drive an irrigation pump at the site. The solar thermal system is to operate in a Rankine-cycle using an organic working fluid. The engine is in the form of a multi-vane expander. The solar-energy collector comprises of an array of gravity-assisted heat- pipes each enclosed within a cylindrical high-vacuum glass tube. The irrigation water which is to be sucked from below ground level, is also to cool the shell-and-tube condenser. The first section(i. e. PART A) of this thesis is a presentation of some design optimization concepts in the development of the thermodynamically operated solar-energy system. As in any desert area dust will constitute a problem, reducing the harnessing capability of the collector array. Regular cleaning would therefore be essential. However, cleaning a large array (1000) of such fragile tubes in situ is unlikely to be accomplished without cracks and breakages occurring. This perhaps means that the high-vacuum which is essential for each collectors continued adequate thermal performance could be easily lost. The collectors are also considered expensive. For example, one tube with an effective aperture area of about 0.102ml costs about twenty pounds Sterling. These and the fact that the maximum anticipated working temperature in the organic Rankine-cycle would be about 1201 C, led to the study into a means other than evacuation of reducing thermal losses from the receiver of a flat-plate solar-energy collector in the second section (i. e. PART B). A flat-plate collector employing a simple slatted convection suppression device was studied. It was shown that a flat-plate collector employing an effective convection suppression device and an initial cost of about £1o0/m'would be more cost effective than the evacuated-tube collector, when employed to activate the pilot power plant for operatinq temperaures of (80-X120)° C. The cost per peak watt could be reduced by an average value of about 15% depending upon the'operating temperture. Whereas the break-even time against electricity could be reduced by about 4%. However, the overall efficiency of the power plant could fall by an average value of about 23%, depending upon the operating temperature.

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This thesis describes the 1983 solar shape investigation performed at the Santa Catalina Laboratory for Experimental Relativity by Astrometry (SCLERA). Solar diameter measurements, with the North Solar Pole defined as θ = 0° polar angle, have been made between the following polar coordinates: from θ = 0° to θ = 180° (the polar diameter), from θ = 90° to θ = -90° (the equatorial diameter), from θ = -45° to θ = 135° and from θ = 45° to θ = -135°. Expressing the Sun's apparent shape in terms of a Legendre series, these diameters have enabled the calculation of the P₂ (quadrupole) and P₄ (hexadecapole) shape coefficients. The theoretical framework used to provide a relationship between the observed shape of the Sun and the multipole moments of the solar gravitational potential field has been improved to include, in general, the effect of differential rotation in both latitude and radius. Using the shape coefficients and the theoretical framework, the gravitational potential multipole moments, expressed as the P₂ and P₄ coefficients of a Legendre series, have been found to be J₂ = (3.4 ± 1.3)E-6 and J₄ = (1.7 ± 1.1)E-6, respectively. It has been found that the contribution to the perihelion precession of Mercury's orbit, caused by the combined effects from the gravitational quadrupole term and general relativity, was approximately 1σ different from the observed amount after all other known Newtonian contributions had been removed from the observed precession. The total apparent oblateness ΔR (equator-polar radii) found from SCLERA observations is ΔR = 13.8 ± 1.3 milliarcseconds. The surface rotation contribution ΔR' to the apparent solar shape is ΔR' = 7.9 milliarcseconds. The quoted uncertainties represent formal statistical 1σ errors only. Also, it has been shown that large changes in the apparent limb darkening functions were occurring near the equatorial regions of the Sun during the time of the observations. Evidence for periodic shape distortions near the equator have also been found.

A versatile solar spectroradiometer has been designed which is capable of measuring direct solar radiation, the solar aureole, and sky radiance far from the sun. An active tracker consisting of a quadrant detector, telescope and stepper-motor driven alt-azimuth mount is used to position the spectroradiometer by computer control for solar tracking and almucantur scans. An internally baffled telescope designed to suppress stray light is employed as the optical receiver, and a photodiode serves to convert the collected flux to an electrical signal. A digitally controlled gain-switching transimpedance amplifier is used to scale the photodiode output to accommodate the large signal range encountered between measuring direct solar radiation and sky radiance well away from the sun. Example measurements are presented which demonstrate the system's capabilities.

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