Preliminary investigation for the production of wet-process phosphoric acid from Saudi phosphate ores

This paper represents the first published report of a preliminary investigation of the possibility of using Saudi phosphate ores for the production of wet-process phosphoric acid.     

Evaluation of corrosion behavior of Al-Mg-Li alloys in seawater

Weldalite 050, a high-strength Al-Mg-Li alloy, was evaluated for its corrosion resistance in deaerated and air saturated Arabian Gulf water to determine its suitability for marine applications. Weight loss and electrochemical studies showed that the alloy had minimum corrosion rates of 1.82 and 4.82 mpy (mils per year), respectively, in deaerated and air saturated Arabian Gulf water with very high total dissolved solids (TDS) content. Weldalite 050 exhibited good resistance to corrosion at velocities up to 3.9 m/s. The formation of Al₂MgLi, Al-Li, Al₁₂Mg₁₇, and Al-Li precipitates has a pronounced effect on its corrosion resistance. The corrosion resistance of Weldalite 050 compares favorably with that of alloys 5052 and 5054, wrought alloys 6061 and 6013, and silicon carbide (SiC) reinforced alloys 6061 and 6013.     

A Model for the Estimation of Viscosity of Pure Hydrocarbon Liquids

 

A simple model is developed for the estimation of viscosity of hydrocarbon liquids considering that drag on molecular motion due to thermal energy is balanced by intermolecular attractions. The model equation is validated with National Institute of Standards and Technology data on hydrocarbon liquids (C₃-C₁₀ and C₁₂) considering the effect of molecular shape on drag force. The molecular shape is correlated well with molecular weight of hydrocarbon liquids. The accuracy of the proposed model equation is compared with the correlation. The result showed that the proposed model is more accurate. The proposed model equation predicts the viscosity over a wide range of temperature for C₃-C₂₅ with overall absolute average deviation of 5.13%.     

Laser nitriding of tool steel: thermal stress analysis

In this paper, bees algorithm (BA) has been used for determine the optimal number of material handling equipment (MHE) used on the production centers. The unmet demands become zero at the end of the planning horizon, i.e., the part demands are totally satisfied through the horizon. The newly developed model provides network information, such as unmet demands and number of loaded and empty of MHE at any given time and centers. Consequently, the model provides a tool for helping managers with planning and decision-making in manufacturing systems. Computational tests showed that small-sized instances can be solved by the exact approach in a fair amount of central processing unit time, but it is not feasible for medium and large-sized instances. To tackle this problem, a bees algorithm is proposed to solve the model. The algorithm is a search procedure inspired by the way honeybees forage for food. The results obtained show the robust performance of the bees algorithm.     

Axi-symmetric tube extrusion/piercing using die–mandrel combinations: some experiments and a generalised upper bound analysis

A generalised upper bound technique is applied to the solution of working pressures in extrusion–piercing of hollow tubes starting from either solid circular or initially hollow billets by using axi-symmetric die–mandrel combinations of different shapes. Characteristic deformation modes during processing of these tubes made of tellurium lead and commercially pure aluminium were studied experimentally and the results presented. Estimates of working pressures based on the generalised upper bound analysis are compared with the experimental and with those estimated earlier from the slab method of analysis given in Chitkara and Aleem (International Journal of Mechanical Sciences, submitted for publication). These show good co-relations with each other and with the experiments.     

Extrusion of axi-symmetric tubes from hollow and solid circular billets: : a generalised slab method of analysis and some experiments

To analyse the mechanics of extrusion of an axi-symmetric tube starting from either a hollow or a solid circular billet, a generalised analytical approach based on the slab method of analysis is developed for a somewhat general case of tube extrusion through a general profile-shaped die and over a general profile-shaped mandrel. The results of mean extrusion pressures obtained from the theoretical analysis for the various die–mandrel combinations are compared with the experimental investigation carried out on a model material and with the work of other authors. These show reasonably good agreements.     

Review and application of closed-loop systems in flow-induced corrosion

Various closed-loop systems have been developed in recent years to investigate flow-induced corrosion. Because of different parameters and techniques used by investigators, interpretation of results is often confusing and complicated. This paper presents a review of important techniques employed and interpretation of corrosion data.     

Chromosome instability and unusual features of some widely used strains of Candida albicans

Electrophoretic karyotyping of the Candida albicans revealed a different migration pattern of ChR in three different stocks of the sequencing strain SC5314. In one stock, the high instability of ChR size prevented the migration of ChR as a compact band; ChR appeared, instead, as a smear. In some stocks, ChR and/or Ch1 ploidy diminished, suggesting mixed populations of disomic and monosomic cells. Similarly, some stocks of widely used derivatives CAI4 and BWP17 contained smearing of ChR. In addition, the most manipulated strain in the lineage of SC5314, the last derivative, BWP17, acquired an increase in the size of Ch7b and revealed an unusual property. BWP17 did not tolerate a well-established procedure of telomere-mediated fragmentation of a chromosome; the remaining intact homologue always duplicated. We suggest that some stocks of SC5314 are unstable and that BWP17 may not be appropriate for general studies. Instead of BWP17 or CAI4, we recommend using for general research CAF4-2, which is a relatively stable Ura- derivative, and which has been successfully used for more than a decade in our laboratory.