4,858 research outputs found
Optimising of a domestic paraffin geyser for rural application
No full textA water heating system based on paraffin was investigated. Such a system fulfils a need in rural areas where electrify is not available and solar geysers are not practical. The solution is particularly apt due to the abundant use of paraffin in rural communities. The system was modelled for the previous conference and it was apparent that the product required some optimisation in order to be practical. The product was then optimised in terms of increasing the heat transfer area available and an improvement of 87% in terms of performance was achieved with an 8% reduction in cost to manufacture. This provided a solution that proved more practical when heating water to a suitable showering temperature of 38°C. A flow rate of 4.71/min with warmer summer water inlet conditions was achieved and 3.21/min with colder winter water inlet conditions. The product offers a great deal of versatility due to the nature of inline heat exchangers. It is possible to adjust the outlet water temperature by adjusting only the water flow rate. Thus the product can provide water at any range of temperature from a warm temperature for showering to boiling waterhttp://140.98.202.196/xpl/mostRecentIssue.jsp?punumber=682008
The integrated effect of moderate exercise on coronary heart disease
No full textBackground: Moderate exercise is associated with a lower risk for coronary heart disease (CHD). A suitable integrated model of the CHD pathogenetic pathways relevant to moderate exercise may help to elucidate this association. Such a model is currently not available in the literature.
Methods: An integrated model of CHD was developed and used to investigate pathogenetic pathways of importance between exercise and CHD. Using biomarker relative-risk data, the pathogenetic effects are representable as measurable effects based on changes in biomarkers.
Results: The integrated model provides insight into higherorder interactions underlying the associations between CHD and moderate exercise. A novel ‘connection graph’ was developed, which simplifies these interactions. It quantitatively illustrates the relationship between moderate exercise and various serological biomarkers of CHD. The connection graph of moderate exercise elucidates all the possible integrated actions through which risk reduction may occur.
Conclusion: An integrated model of CHD provides a summary of the effects of moderate exercise on CHD. It also shows the importance of each CHD pathway that moderate exercise influences. The CHD risk-reducing effects of exercise appear to be primarily driven by decreased inflammation and altered metabolis
Vacuum Insulation Panels Applied in Building Constructions
No full textDue to sustainability and due to international treaties, it is desired and required to reduce greenhouse gas emissions drastically. One contributor to these emissions is the burning of fossil fuels for generating power and electricity to be used in and for buildings. Buildings and building-related processes are responsible for about 40% of the primary energy consumption in the European Union. More than half of this energy is applied for heating systems in dwellings and commercial buildings. The European Union therefore has laid down new energy performance requirements for buildings in the European Directive on the Energy Performance of Buildings. Moreover, a reduction of energy losses of buildings during their occupational phase is important for facilitating the implementation of sustainable energy sources in the built environment. Increasing the insulation value of the envelope of buildings may contribute to this reduction of primary energy use. Two strategies can be followed. The first strategy is to increase the thickness of the thermal insulation layer. Until recently, this strategy has primarily been adopted. If, however, German or Swiss Passivhaus standard is applied, the thickness of this insulation layer would increase to beyond 30 cm, resulting in very thick building enclosures. The second, more innovative, strategy for reducing energy losses through the building skin would be the application of more effective thermal insulators. One such more effective thermal insulator is a vacuum insulation panel, abbreviated as VIP. A VIP consists of an open-celled core material which is evacuated and then tightly sealed into a barrier envelope to maintain this vacuum. The vacuum inside the pores of the core material reduces the thermal conductivity of the product significantly, as a result of which the thickness of the insulation layer can be reduced to obtain a certain performance. This reduction of thickness is among the most promising features for large-scale application of VIPs in the building industry. However, integration of VIPs into buildings must be performed very meticulously for several reasons; first, due to its nature a VIP cannot be processed on site and needs careful planning in advance; second, it is very sensitive to mechanical damage thus requiring careful handling; third, thermal bridges along the panel’s edges reduce its performance; fourth, the composite system is highly subjected to aging. This dissertation therefore looks into many of these aspects, presents several calculation tools and shows how VIPs can be applied in façade panels, EPS insulation boards and as under-floor insulation. With the wide-spread proliferation of VIPs in buildings a more sustainable and healthy environment can then be achieved.Building TechnologyArchitectur
Supply Invoice, March 22, 1898
No full textBill: To M.J. Glover, Mathews Bluff, [South Carolina], listing supplies and transportation charges. Handwritten notations on back
Book Review: Reginald M.J. Oduor’s Introduction to Ethics
No full textTITLE OF BOOK: Introduction to Ethics
AUTHOR: Reginald M.J. Oduor
Nairobi: Sophia Publications Ltd., 2009, 116 pages
COVER: Paperback
ISBN: 9966-7457-0-X
This book is a product of more than a decade of Oduor’s experience in teaching ethics (moral philosophy) at the University of Nairobi. In the course of this introduction, the reader gets to see the techniques of philosophic reflection in action, as they are employed to scrutinise various pertinent moral questions
Comments on “Precipitation kinetics of Al–1.12Mg2Si–0.35Si and Al–1.07Mg2Si–0.33Cu alloys”
No full textIt is shown that in analysing DSC data of precipitation reactions in Al–1.12Mg2Si–0.35Si, Al–1.07Mg2Si–0.33Cu and Al–1.0Mg2Si–0.5Ag alloys in work by Gaber et al., accurate values for the activation energies are obtained by applying the method derived by the present author (the Type B-1.92 method). Values obtained from other analysis methods reported by Gaber et al. are less accurate. Averaging activation energies obtained by different methods introduces inaccuracies and obscures these inaccuracies, especially if the set of methods applied includes highly inaccurate ones, such as the Ozawa and Takhor methods
Optical Flow Based State Estimation for an Indoor Micro Aerial Vehicle
No full textThis work addresses the problem of indoor state estimation for autonomous flying vehicles with an optic flow approach. The paper discusses a sensor configuration using six optic flow sensors of the computer mouse type augmented by a three-axis accelerometer to estimate velocity, rotation, attitude and viewing distances. It is shown that the problem is locally observable for a moving vehicle. A Kalman filter is used to extract these states from the sensor data. The resulting approach is tested in a simulation environment evaluating the performance of three Kalman filter algorithms under various noise conditions. Finally, a prototype of the sensor hardware has been built and tested in a laboratory setup. Paper published: Verveld, M.J., Chu, Q.P., De Wagter, C. and Mulder, J.A. “Optic Flow Based State Estimation for an Indoor Micro Air Vehicle” AIAA Guidance, Navigation, and Control Conference, August 2010, Toronto, Canada AIAA 2010-8209, DOI: 10.2514/6.2010-8209Aerospace EngineeringControl & Simulatio
Transient time-averaged spectra of rapidly-modulated semiconductor lasers
No full textUsing the computed solution of multimode rate equations, and including wavelength-chirping effects via the dependence of the refractive index on carrier concentration, it is possible to calculate time-averaged spectra of rapidly-modulated lasers. The averaging time may be used to simulate the effects of measuring equipment with a specific time response. The results show a characteristic line structure within the dominant longitudinal mode spectrum, and are in qualitative agreement with experimental measurements reported by other author
Gift inscription in Minions of the Moon: a little book of song and story
No full textThis edition includes a gift inscription possibly penned by the author, Madison Julius Cawein, "Frank on Valentines Day, 1914. M.J." Madison Julius Cawein (1865-1914).Cawein, Madison Julius, 1865-1914
Cooling and heating rate dependence of precipitation in an Al-Cu alloy
No full textDifferential scanning calorimetry and X-ray diffraction were used to study the cooling and heating rate dependence of precipitation in an Al-1.66 at.% Cu alloy. After homogenizing, cooling at a rate of 22 K min?1 (SC22) is sufficient to retain all copper in solid solution. GP-zone formation during subsequent heat treatment is hindered; this is ascribed to an insufficient number of (excess) vacancies. After a water quench (WQ) a large number of GP zones are formed during subsequent storage at room temperature for 1 h. The heat content of the GP-zone dissolution effect can quantitatively be described in terms of the heat of precipitation of GP I zones and the solid solubilities as derived from the GP I zone solvus. The heat content of the combined ??-/?-phase precipitation effect appeared to be proportional to the number of copper atoms precipitated, yielding an average value for the heat of copper precipitation of 36 kJ mol?1 copper. The activation energy for ??-phase formation is 0.75 eV for SC22 specimens and 1.10 ± 0.10 eV for WQ specimens. The differences in reported activation energies for ??-phase formation are discussed in terms of mobility of dissolve atoms (related to the vacancy concentration), interfacial energy and direction of growth (normal or perpendicular to the ??-phase plate)
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