Charge-discharge characteristics of a lead oxide-zinc secondary battery system

Performance characteristics of a rechargeable cell using PbO₂ and Zn electrodes and inorganic sulphate electrolytes were studied and compared to those of a conventional lead-acid test cell. The PbO₂-Zn battery exhibits only limited advantages over the lead-acid system.     

Estimating the global solar radiation for solar energy projects – Egypt case study

The main objective of this paper is to determine the best models for estimating the global solar radiation (GSR) on a horizontal surface over Egypt. A model selection criterion is used to determine the best model for each site. A general two-stage method is developed. In the first stage, 40 popular empirical models are evaluated for a specific set of sites in Egypt. In the second stage, Egypt is divided into a set of regions each of which is described by the best found GSR model. The determined regions and regional models are based on the results of the first stage and determined based on the determined best model for the sites contained in a specific region. The results show that the solar radiation over the whole lands of Egypt can be characterised by two models: the Iranna and Bapat 10P GOB 1 and the K?l?c and Ozturk.     

Effect of polymethylmethacrylate–montmorillonite nanocomposite on the release of some biologically active 1,2,4‐triazine derivatives

Methylmethacrylate chloromethylstyrene copolymer–montmorillonite (PMMA–MMT) intercalated nanocomposite was prepared by bulk copolymerization of methylmethacrylate (MMA) and chloromethylstyrene (2 wt%) followed by phosphonium salt formation. The intercalation of polymeric phosphonium salt into montmorillonite was achieved through an ion exchange process between sodium cations in MMT and phosphonium groups attached to the copolymer. Thermogravimetric analysis (TGA) showed improved thermal stability for the intercalated nanocomposite in comparison with the pure PMMA. Biologically active compounds including 4‐amino‐6‐methyl‐3‐thioxo‐3,4‐dihydro‐2H‐[1,2,4]triazin‐ 5‐one (I), 4‐amino‐6‐methyl‐3,4‐dihydro‐2H‐[1,2,4]triazin‐3,5‐dithione (II), 4‐amino‐6‐(4‐methoxystyryl)‐3‐thioxo‐3,4‐dihydro‐2H‐[1,2,4]triazin‐5‐one (III), and 4‐amino‐6‐styryl‐3‐thioxo‐3,4‐dihydro‐2H‐[1,2,4]triazin‐5‐one (IV) have been prepared and reacted with PMMA–MMT intercalates and ion exchanged with sodium montmorillonite (MMT) in the presence of HCl. Infrared spectra (IR) show bands characteristic to amide linkage between triazine derivatives and PMMA. These nanocomposites have been characterized by X‐ray diffraction (XRD) and transmission electron microscope (TEM). The release of biologically active compounds intercalated layered silicates is controllable and these materials have a great potential as a delivery host in the pharmaceutical field. The effect of temperature and presence of saline solution on the release was studied. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers     

Estimation of sensitivity coefficients of core characteristics based on reduced-order modeling using sensitivity matrix of assembly characteristics

We propose an estimation method of sensitivity coefficients of core neutronics parameters based on a multi-level reduced-order modeling approach. The idea is to use lower-level models to identify the dominant input parameter variations, constrained to the so-called active subspace, which are employed to determine the sensitivity coefficients of the core neutronic parameters. In our implementation, the lower-level model is represented by two-dimensional assembly calculations, which are employed in the preparation of the few-group cross-sections for core-wide calculations. The active subspace basis is estimated using the singular value decomposition of sensitivity matrices of assembly neutronics parameters. In numerical verification calculation, sensitivity coefficients of core characteristics for a typical three-loop PWR equilibrium-cycle are estimated using the proposed method and the direct method. Comparison of these two results shows that the proposed method well reproduces the results obtained by the direct method with lower calculation costs. Through the verification calculations, applicability of the proposed method to practical light water reactor analysis is confirmed.     

Scale-up of the deposit ion-threshold voltage in the electrodeposition of bright chromium

A single nonlinear equation is described whose root yields the minimum potential drop required for the onset of bright chromium deposition as a function of electrode size and separation.     

Thermolysis of mono-, di- and tri-benzylamines,IV

Thermolysis of mono-, di- or tri-benzylamine for some days in the absence of promoters gave the same products: ammonia, toluene, dibenzyl, stilbene and benzaldehyde. Thermolysis of dibenzylamine in isoquinoline as a solvent gave 1-benzyl-isoquinoline together with the normal pyrolysis products. When naphthalene and 2-naphthol are used as solvents, benzylation of the solvent nuclei was observed to give 1- and 2-benzylnaphthalenes and 1-benzyl-2-naphthol respectively. In conclusion, thermolysis of tri-, di- or mono-benzylamines proceeds through a free radical mechanism with successive conversions of the tertiary, through secondary to primary alkylamines resulting in the same pyrolysis products.     

Effect of some operating variables on the flotation of aluminium particles

The effects of impeller speed, air flow rate, cell concentration, agitator size and cell volume on the recovery of aluminium particles have been studied in a KHD Humboldt Wedge AG machine, using alkyl benzene sodium sulphonate paste as collector and pine oil as frother. The recovery yield increased with increasing impeller speed, air flow rate, cell concentration and cell volume, up to a certain range, whereafter it decreased. A decrease in the recovery yield was observed on increasing the agitator size. A mathematical model has been developed to correlate percentage recovery with the above variables.     

An experimental investigation of convection patterns in flow past an obstacle

The propagation of liquid flow in a cylindrical tube past solid obstacles of various shapes and sizes has been studied at Reynolds numbers up to about 6,600 via a direct electrochemical flow visualization technique where the obstacles were connected as cathodes and the colour change of a suitable analytical indicator was employed for the marking of convecting flow. Typical propagation patterns are shown by photographs and the effect of the obstacle on local velocities at the core of tube is analyzed.