Operation of Sardar Sarovar Conveyance System

Conveying 11.7 BCM of water annually over a distance of up to 700 km fulfilling the functional requirements such as safety, flexibility, dependability, equity of distribution and efficiency is challenging by any standard. Operation of the Sardar Sarovar Conveyance System is even more critical because of its unprecedented size, complexity, value of water for the drought-prone areas and inter-state commitments. This paper analyses the functional requirements of the system vis-à-vis the limitations of conventional operation. The Controlled Volume Concept of operation through remote monitoring and a control system is adopted, which calls for canal automation as a 'solution'. Discussing issues such as maintenance, training, economic evaluation etc., the paper concludes that the pilot project taken up on Vadodara DOC will be a forerunner for other irrigation projects.     

Modeling of chip–tool interface friction to predict cutting forces in machining of Al/SiCp composites

In Al/SiCp metal matrix composites, in addition to machine, tool and process-related parameters, a change in composition (size and volume fraction of reinforcement) has a influence on machining force components. In the analytical models in the literature, the effect of abrasive reinforcement particles, which affects the coefficient of friction and consequently the friction angle, has not been considered while predicting cutting forces in machining of MMCs. In this paper, chip–tool interface friction in machining of Al/SiCp composites has been considered to involve two-body abrasion and three-body rolling caused due to presence of reinforcements in composites. The model evaluates resulting coefficient of friction to predict the cutting forces during machining of Al/SiCp composites using theory of oblique cutting. Further, the model considers various frictional forces on the wiper geometry on the cutting edge that has been found to improve the integrity of machined surface on composites. The predicted cutting force values were found to agree well with the corresponding experimental values for finer reinforcements composites with the assumption that 40% of the reinforcement particles contribute to the abrasion at chip–tool interface. However, for the coarser reinforcement composites, assumption that the 60% of the particles contribute to the abrasion yields better results.     

Polybutylene terephthalate/high-density polyethylene alloys. I. Morphological studies

Polybutylene terephthalate (PBT) is a commercially successful thermoplastic polyester but has certain drawbacks such as low impact strength and low melt strength. An attempt has been made to modify the properties of PBT by blending it with polyolefin such as highdensity polyethylene (HDPE). Since PBT and HDPE are incompatible, an ionomer has been used as a compatibilizer to form an alloy. Alloys of PBT and HDPE with varying amounts (2-8%) of ionomer were prepared by melt blending. The ultimate mechanical properties improved significantly on the addition of the ionomer due to an increase in interfacial adhesion between PBT and HDPE. DSC studies show that the presence of ionomer facilitated the crystallization of PBT in the alloy. DMTA studies show that more of PBT (amorphous) is going in to the HDPE-rich phase in the presence of ionomer. The morphology of the alloys was studied using scanning electron microscopy (SEM), polarizing microscopy (PM), and small-angle light scattering (SALS). They showed improved dispersion of HDPE domains in PBT matrix with increasing ionomer content and change in the type of superstructure on adding the ionomer. It has been shown that an alloy of PBT and HDPE with improved mechanical properties and homogeneous morphology can be made with use of ionomer as a compatibilizer. Such alloys are cost effective and can find use in several engineering applications.     

A new public-domain simulator for power electronic circuits

A new public-domain simulator (SEQUEL) for power electronic circuits is described. The organization of the simulator is briefly discussed. The most important feature of the simulator is that the user can define new elements in a flexible manner. The differences between the new simulator and other simulators are enumerated. Some simulation examples are discussed to demonstrate the applications of the simulator. It is pointed out that the new simulator is particularly attractive for engineering institutes in developing countries where access to expensive commercial packages with similar capabilities may be difficult     

Segregation and intermixing in polydisperse liquid–solid fluidized beds: A multifluid model validation study

Multifluid model (MFM) simulations have been carried out on liquid–solid fluidized beds (LSFB) consisting of binary and higher-order polydisperse particle mixtures. The role of particle–particle interactions was found to be as crucial as the drag force under laminar and homogenous LSFB flow regimes. The commonly used particle–particle closure models are designed for turbulent and heterogeneous gas–solid flow regimes and thus exhibit limited to no success when implemented for LSFB operating under laminar and homogenous conditions. A need is perceived to carry out direct numerical simulations of liquid–solid flows and extract data from them to develop rational closure terms to account for the physics of LSFB. Finally, a recommendation flow regime map signifying the performance of the MFM has been proposed. This map will act as a potential guideline to identify whether or not the bed expansion characteristics of a given polydisperse LSFB can be correctly simulated using MFM closures tested.