Fuel cells for non-automotive uses: Status and prospects

Fuel cells are in varying stages of commercialization for both automotive and non-automotive applications. The fuel cell industry has made substantial progress but still needs to reduce costs and improve performance to compete successfully with established technologies. In just 5 years, costs have been reduced by a factor of two while improving efficiency and durability. Based on interviews with fuel cell manufacturers in the U.S., Japan and the EU and information from published sources, a model of non-automotive fuel cell markets is constructed and used to estimate the impacts of government policies and to project the potential evolution of the industry to 2025. The model includes the effects of learning-by-doing, scale economies and exogenous technological progress on component and system costs, estimates customer choices between fuel cell and competing established technologies, and attempts to measure the impacts of government policies. With continued policy support it appears likely that the industry can become self-sustaining within the next decade.     

A mathematical model for mammary fatty acid synthesis and triglyceride assembly: the role of stearoyl CoA desaturase (SCD)

An increase in the proportion of unsaturated fatty acids in milk is considered desirable for human health. A prerequisite for the manipulation of milk fat composition is a co-ordinated understanding of the complex interactions in its biosynthesis. It has been suggested that an increase in the expression of mammary stearoyl-CoA-desaturase (SCD) would enrich mono-unsaturated fatty acids in milk, and therefore improve its nutritional properties. To investigate the potential effects of changes in expression of mammary enzymes and substrate availability on milk fat composition, we constructed, parameterized and evaluated a mechanistic mathematical model of fatty acid biosynthesis and milk-fat triglyceride assembly. The objective was to describe changes in the amount and composition of milk fat produced by bovine mammary cells due to changes in nutrition. Using the model we found that a 50% up-regulation in SCD activity increased the molar fraction of milk triglyceride 18:1 from 0.30 to 0.33 and 16:1 from 0.04 to 0.06. Up-regulation of SCD therefore did not appear to be the optimal method for increasing the content of unsaturated fatty acids in milk fat. The model was also used to determine the likely rate-limiting processes for the incorporation of unsaturated fatty acids into milk fat. Halving the concentration of glycerol 3-phosphate increased the molar fraction of milk triglyceride 18:1 from 0.30 to 0.35 and decreased the molar fraction of milk triglyceride 16:0 from 0.30 to 0.22. This achieved the desirable outcome of producing more unsaturated low-fat milk. Our model also predicted that a K232A mutation in the bovine mammary DGAT1 gene that is linked with an increase in milk fat yield would be consistent with a 120% increase in the DGAT acylation rate and also would be associated with a decrease in milk mono-unsaturated fatty acids.     

Micro-irrigation development in India: an analysis of distributional pattern and potential correlates

ABSTRACT

In India, of late, micro-irrigation has received considerable policy focus. However, as of 2017, only about 10% of the potential area is under micro-irrigation. The present study analyzes the pattern and equity issues of distribution of micro-irrigation in India and identifies the potential correlates. The regression analysis reveals that the stage of groundwater development and agro-climatic differences significantly influence the spread of micro-irrigation. The relatively low spread of micro-irrigation in states with over-exploited groundwater needs attention. Overall, the study points to the need to revamp the current micro-irrigation development programmes, which focus excessively on subsidy.     

Analysis of grey wolf optimizer based fractional order PID controller in speed control of DC motor

Microsystem Technologies - The present work deals with comparative and robustness analysis of grey wolf optimization (GWO) based fractional order proportional–integral derivative (FOPID)...     

The consequences of different temperatures on pore structure development in carbon

Particles of a porous, degassed Wyoming coal were reacted with carbon dioxide under surface-rate-limited conditions using a differential reactor. Different temperatures were used, and as the reaction progressed, extensive pore-structure measurements were made. This enabled the pore development to be followed at the different temperatures. Several characteristics of the burning were notable. The intrinsic surface rates (i.e., the reaction rates per unit surface unaffected by diffusion) in the macropores differed from those in the intermediate pores, and in turn the surface rates in the intermediate pores differed from those in the micropores. The intrinsic burning rates of the different sizes of pores relative to one another changed with temperature. The intrinsic burning rates of the different sizes of pores relative to one another also changed with burnoff. These three characteristics indicate that the parameters in the rate equation (pre-exponential factors and activation energies) changed with both pore size and extent of reaction. In the macropore system (pore radius >10 nm), the material constricting the pores appeared to burn faster than the material composing the bodies of the pores. In the intermediate pore system (1 nm < pore radius < 10 nm), there was some evidence of single-crystal burning to produce pores of the same size as the carbon crystallites. The last two of these characteristics have been observed before, but the first three appear to have gone unreported.     

Scheduling job shop associated with multiple routings with genetic and ant colony heuristics

The general job shop problem is one of the well known machine scheduling problems, in which the operation sequence of jobs are fixed that correspond to their optimal process plans and/or resource availability. Scheduling and sequencing problems, in general, are very difficult to solve to optimality and are well known as combinatorial optimisation problems. The existence of multiple job routings makes such problems more cumbersome and complicated. This paper addresses a job shop scheduling problem associated with multiple job routings, which belongs to the class of NP hard problems. To solve such NP-hard problems, metaheuristics have emerged as a promising alternative to the traditional mathematical approaches. Two metaheuristic approaches, a genetic algorithm and an ant colony algorithm are proposed for the optimal allocation of operations to the machines for minimum makespan time criterion. ILOG Solver, a scheduler package, is used to evaluate the performance of the proposed algorithms. The comparison reveals that both the algorithms are capable of providing solutions better than the solution obtained with ILOG Solver.     

Scalable processes for fabricating non-volatile memory devices using self-assembled 2D arrays of gold nanoparticles as charge storage nodes

We propose robust and scalable processes for the fabrication of floating gate devices using ordered arrays of 7 nm size gold nanoparticles as charge storage nodes. The proposed strategy can be readily adapted for fabricating next generation (sub-20 nm node) non-volatile memory devices.     

Investigations on thiourea content in ternary Sn–Ag–Cu bath using electrochemical studies

We have developed a methane sulfonic acid (MSA) based ternary electrolytic bath for co-deposition of the eutectic Sn–Ag–Cu films. The bath contains thiourea (TU), which functioned as an effective chelating agent in controlling the bath stability as well as the elemental and microstructural properties of the deposited film. A study of the bath behaviour at TU concentrations in the range 0.06–0.2 M is undertaken with the help of elemental and microstructure analysis, cyclic voltammetry (CV) and impedance analysis. The deposited films have close to eutectic composition with slightly higher Cu content for all the TU concentrations. On the other hand, the microstructure is found to be increasingly refined with increasing TU content. The CV and impedance analysis confirm chelation of Ag and Cu with TU and absence of such chelation with Sn ions. It also indicates close deposition potentials for each metal ion. Impedance analysis specifically reveals presence of an adsorbed insulating film on cathode surface, contributed by MSA or water. It also reveals competitive deposition between the insulating film and metal ions.     

Particle size effects on the slurry erosion of aluminium alloy (AA 6063)

The effect of particle size on erosion wear of aluminium alloy (AA 6063) has been investigated in a slurry pot tester. Eight different sized quartz particles with mean size varying between 37.5 and 655 μm have been used. The wear specimens are rotated inside the pot at 3 m/s velocity with orientation angle of 30° and 90° in a sand–water mixture of 20% concentration (by weight). It is seen that the erosion wear increases with increase in mean particle size. Two distinct mechanisms are noticed for mean particle size above 200 μm and below this size for the range of parameters under this investigation. It seems that a threshold kinetic energy of impacting particle may exist, which results in change in the wear rate at a particular particle size. The threshold kinetic energy for different operating conditions has been determined and its relation with the change in erosion mechanism is discussed.