Etude de la circulation dans les bassins d'aeration a boues activeesStudy of the circulation pattern in aeration tanks

Keeping the mixed liquor in suspension is one of the critical problems in aeration tanks. This can only be assured by adequate circulation of the liquid. A hydrodynamic study in different laboratory and industrial scale aeration tanks, has been carried out to characterise the circulation (bottom velocity, V_f, mean circulation velocity) using the following parameters i.e. tank geometry and air flow rate G. This study also proposes a scale-up criterion for aeration tanks. All the dimensions of these tanks are given in Table 1.     

Experimental study of conjugate heat transfer within a bottom heated vertical concentric cylindrical enclosure

In this research work an experimental study of conjugate heat transfer within an air filled bottom-heated vertical enclosure is conducted. The enclosure consists of two concentric cylinders with inner cylinder being shorter and open at the top. The study is important with respect to the centrifuge machine used in the process industry. Eighteen different experiments are performed by varying the bottom disc central temperature between 353 and 433 K, using three different materials (aluminum, mild steel and stainless steel) of the inner cylinder and two different diameter outer cylinders of mild steel. This study unfolds the temperature, material and geometric effects of bottom disc, inner cylinder and outer cylinder respectively on thermal convection in the enclosure. Generally, a uniform temperature is required in such enclosures. A more uniform axial and radial temperature is observed in the enclosure by using aluminum inner cylinder within a temperature range of 353–433 K of the bottom disc and using two different diameter outer cylinders. It is observed that the maximum temperature in the enclosure is lowest for aluminum inner cylinder and higher for mild steel and highest for stainless steel. The heat balance and non-dimensional analysis of the enclosure are carried out and discussed critically.     

The preparation of cadmium phosphate and cadmium zinc phosphate glasses and their electrical and optical properties

The preparation of a range of glasses based on CdO-P₂O₅ and CdO-ZnO-P₂O₅ is described and data are reported on density, electrical conductivity and optical absorption. The electrical conduction is electronic rather than ionic and is due to hopping between localized states. The optical absorption is due to forbidden indirect electronic transitions.     

Radioisotope container cum automatic dispenser

The paper describes the design of a radioisotope container and the method used for calculation of the shield dimensions necessary to bring down the surface radiation dose to a desired level. Two such containers were fabricated, each to handle 25 Ci of scandium-46 sand in 16 glass ampoules. Since the containers were also to be used for transportation of the activity over 1000 miles by road [1] the ampoule housing was felt-lined to absorb shocks.     

Development of ethanolamine‐based ionic liquid membranes for efficient CO2/CH4 separation

This study is focused on the development of ionic liquids (ILs) based polymeric membranes for the separation of carbon dioxide (CO₂) from methane (CH₄). The advantage of ILs in selective CO₂ absorption is that it enhances the CO₂ selective separation for the ionic liquid membranes (ILMs). ILMs are developed and characterized with two different ILs using the solution‐casting method. Three different blend compositions of ILs and polysulfone (PSF) are selected for each ILMs 10, 20, and 30 wt %. Effect of the different types of ILs such as triethanolamine formate (TEAF) and triethanolamine acetate (TEAA) are investigated on PSF‐based ILMs. Field emission scanning electron microscopy analysis of the membranes showed reasonable homogeneity between the ILs and PSF. Thermogravimetric analysis showed that by increasing the ILs loading thermal stability of the membranes improved. Mechanical analysis on developed membranes showed that ILs phase reduced the amount of plastic flow of the PSF phase and therefore, fracture takes place at gradually lower strains with increasing ILs content. Gas permeation evaluation was carried out on the developed membranes for CO₂/CH₄ separation between 2 bar to 10 bar feed pressure. Results showed that CO₂ permeance increases with the addition of ILs 10–30 wt % in ILMs. With 20–30 wt % TEAF‐ILMs and TEAA‐ILMs, the highest selectivity of a CO₂/CH₄ 53.96 ± 0.3, 37.64 ± 0.2 and CO₂ permeance 69.5 ± 0.6, 55.21 ± 0.3 is observed for treated membrane at 2–10 bar. The selectivity using mixed gas test at various CO₂/CH₄ compositions shows consistent results with the ideal gas selectivity. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45395.     

Hydrogen Balmer-β and Balmer-γ emission profiles in an abnormal glow region of hydrogen plasma

Emission spectroscopy measurements of Balmer-β and Balmer-γ line profiles are carried out to study their line shapes and line intensities as a function of discharge parameters such as fill pressure (3-7 mbar) and input power (200-400 W). A technique based on determining the relative intensities of neutral atomic hydrogen emission lines is used to evaluate the electron temperature, whereas the electron density is extracted from the Stark broadening (FWHM) of the H_β emission profile. It is found that both the emission intensity and the broadening of the Balmer-β and Balmer-γ lines exhibit significant dependence on the fill pressure in the same manner. However, both the emission intensity and broadening of the H_β line exhibit a weak dependence on input power in contrast to the H_γ emission line. Based on optical measurements reported here, plasma discharge parameters can be selected to optimize the electron temperature and density.     

Chinese Multinational Enterprises in Europe and Africa: How do They Perceive Political Risk?

The concept of political risk has been defined from the perspective of developed-country multinational enterprises (MNEs) and has mainly focused on the political and regulatory perils in developing host countries. However, we have limited understanding of how emerging market firms perceive political risk in international marketplaces. Adopting a case study method, we examine how Chinese MNEs perceive political risk when operating in developed and developing host countries, specifically, the European Union (EU) and Africa. Our findings show that Chinese MNEs regard their home-country origin and industry-specific restrictions as major political risks in the EU. By contrast, they consider the volatile political environment in some African countries as the main source of political risk. In addition to the sharp contrast in the political and regulatory environment between the EU and African states, Chinese MNEs commonly encounter political risks in both markets due to their own behaviour.