The empirical relationship between global radiation and global ultraviolet (0.290–0.385) μm solar radiation components

Measurements of the monthly average daily global and global ultraviolet solar radiation over a period of three years (1985, 1986, 1987) in Kuwait are reported. Over the three years the computed yearly daily means for the above solar radiation components were 5.592 kW h/m² and 0.260 kW h/m². The effect of atmospheric dust on the measured solar radiation components is investigated. Employing the least-square linear regression analysis an estimated empirical function relating global radiation to ultraviolet radiation was proposed for the past three years' measurements.     

Feasibility of using various photovoltaic systems for window-type air-conditioning units under hot-arid climates

This paper reports on the feasibility of using various Photovoltaic (PV) systems namely; Grid PV (GPV), Stand-Alone PV (SAPV), Grid PV Wind (GPVW) and PV Wind (PVW) for supplying the power requirements of a window-type air-conditioning system or other small loads. It was found that the GPVW system is the best system to meet the load requirement of a window-type air-conditioning system under the climatic conditions of Oman with values ranging from $39,500 to $56,500 for the capital cost and $9,000 to $33,000 for the total net capital cost depending on the wind speed. These values are attractive for remote off grid applications.     

Potassium nitrution and nitrogen fixation by nodulated legumes

Seeds ofPisum arvense L.w. Weitor were grown in nitrogen-free nutrient solution for one week and then in the same medium but at a different potassium concentrations (0.0, 0.1 and 10mM) for one month. At the end of the experiment the plants were dried and analysed for total nitrogen, organic carbon, and nutrients (Ca, Mg, Na, K, and P). The number of nodules were counted, and their spatial distribution was studied. The nutrient solution was changed twice a week and analysed for total exuded nitrogen.No positive correlation was found between the total number of nodules and the total nitrogen fixed although nitrogen fixed per one hundred nodules was higher in potassiumrich than in potassium-limited conditions.Plants accumulated higher magnesium concentrations in potassium-limited than in potassium-rich conditions. Roots were relatively more rich in nitrogen (dry weight basis) in potassium-rich conditions. At low supply of potassium a significant amount of the nitrogen fixed was exuded.Increasing the potassium supply increased the total dry weight and total nitrogen fixed by plants but decreased the efficiency of energy (nitrogen fixed per dry weight of green leaves) and potassium utilization for both dry weight production and nitrogen fixation (potassium accumulated per dry weight produced or nitrogen fixed).     

Tolerance to transient faults in microprogrammed control units

The detection of and recovery from transient faults that cause errors in microprogrammed control units are addressed. Error detection is based upon a particular form of signature analysis, namely the run-time computation of a value (the signature) that depends strictly on the microprogram path (the sequence) under execution. The microprogram is statistically segmented (sequences are defined in a fixed way, at design time), and an anticipated signature is associated with each sequence. At run time, at the start of each sequence the computation of the signature is restarted, whereas at the end the computed signature is compared with the anticipated signature of the sequence. If the check is passed, the status of the control unit is saved in suitable registers, and the previously saved status is discarded. If the check fails, the last-saved status is restored (rolled back) and microprogram execution restarts from this last-saved point     

User problems with individual temperature control in offices

Individual thermal control is important for handling personal differences in thermal preference. Several studies have shown that comfort, health and productivity in offices can be improved by individual thermal control. Local controls for temperature are commonly available in modern office buildings. However, office occupants are often still dissatisfied with the thermal environment and their control options. In this study we used contextual techniques to gain an understanding of the user problems with individual temperature control. A total of 27 office occupants in 13 Finnish buildings were interviewed in their offices. They were asked to show and tell us how they use the controls. The results show that the temperature controls were often not used in thermal discomfort. A diversity of problems with individual temperature control was identified and are listed with proposed solutions. The main reason for the many of the problems is that systems are planned and constructed without a realistic view of their users, and end users are presumed to have knowledge they don’t have. The users should be studied and more effort should be put into user interface development.     

Recent Advances in the Modelling of Solid Flows in the Blast Furnace

The solid flow inside a blast furnace is modelled using a standalone finite element program and a constitutive equation called hypo‐plastic, in order to better simulate the granular material behaviour. The parameters of this constitutive equation are calibrated using data obtained from simple soil mechanics tests on coke and sinter materials, such as triaxial and oedometric devices. Steady velocity, stress and void fraction fields are obtained after several iterations of the code. Knowledge of the solids velocity field makes it possible to determine the dead man profile, as well as its renewal kinetics. Burden trajectories and time lines are also computed. Knowledge of the stress field makes it possible to compute pressures acting on the burden as well as on the walls. Finally, knowledge of void fraction field makes it possible to determine gas paths. The solid flow model was validated on 2D and 3D small‐scale cold blast furnaces, but the simulations never required any tuning parameter. This code is in fact an invaluable tool to determine the effect of blast furnace profile on solid flow conditions, and reciprocally.     

A comparative performance study of CFC502, HCFC22 and HFC125

In the paper, the performance of HFC125 as an alternative to CFC502 and R22 is assessed under different operating conditions. Cycle characteristics, such as the thermal capacity, coefficient of performance, pressure ratio, system pressures, temperatures, and compressor power are also discussed. Results obtained after extensive detailed experimental work indicate that the performance is degraded on using HFC125, relative to that obtained with HCFC22.     

Measurements of the suitability of large rock salt formations for radio detection of high-energy neutrinos

We have investigated the possibility that large rock salt formations might be suitable as target masses for detection of neutrinos of energies about 10 PeV and above. In neutrino interactions at these energies, the secondary electromagnetic cascade produces a coherent radio pulse well above ambient thermal noise via the Askaryan effect. We describe measurements of radio-frequency attenuation lengths and ambient thermal noise in two salt formations. Measurements in the Waste Isolation Pilot Plant, located in an evaporite salt bed in Carlsbad, NM yielded short attenuation lengths, 3–7 m over 150–300 MHz. However, measurements at United Salt's Hockley mine, located in a salt dome near Houston, Texas yielded attenuation lengths in excess of 250 m at similar frequencies. We have also analyzed early ground-penetrating radar data at Hockley mine and have found additional evidence for attenuation lengths in excess of several hundred meters at 440 MHz. We conclude that salt domes, which may individually contain several hundred cubic kilometer water-equivalent mass, provide attractive sites for next-generation high-energy neutrino detectors.