Synthesis of cyclic carbonates from carbon dioxide and epoxides using alkali metal halide supported liquid phase catalyst

Using combination of Mn–Co transition metal species with N-hydroxyphthalimide as a catalyst for one-step oxidation of cyclohexane with molecular oxygen in acetic acid at 353 K can give more than 95% selectivity towards oxygenated products with adipic acid as a major product at a high conversion (ca. 78%). A turnover number of 74 for this partial oxidation are also recorded.     

Speed ripple minimization in PM synchronous motor using iterative learning control

Permanent-magnet synchronous motor (PMSM) drives are widely used for high-performance industrial servo applications where torque smoothness is an essential requirement. However, one disadvantage of PMSM is parasitic torque pulsations, which induce speed oscillation that deteriorates the drive performance particularly at low-speeds. To suppress these speed ripples, two iterative learning control (ILC) schemes implemented in the time domain and frequency domain respectively are proposed in this paper. Although a conventional proportional-integral (PI) speed controller does suppress speed ripples to a certain extent, it is not adequate for many high performance applications. Thus, the proposed plug-in ILC controller is applied in conjunction with a PI speed controller to further reduce the periodic speed ripples. Experimental verification of the two schemes is carried out, and test results obtained demonstrate that the scheme implemented in frequency domain has better performance in reducing speed ripples than that implemented in time domain because of the elimination of forgetting factor that is indispensable for robustness in time domain learning method.     

Integrated energy system for industrial complexes. Part I: A linear programming approach

A personal-computer based model of an Integrated Energy System for Industrial Estates (IESIE) has been developed as a pre-feasibility tool: it addresses the total energy concept by combining a set of CHP plant(s), boilers, vapor-compression and absorption chillers, national grid and utility transportation system. The core of the general model is the linear programming (LP) model which takes into account the changing demand-pattern of various loads and their tariffs, standby charge of electricity, unit fuel price, equipment costs, land cost, depreciation, O & M expenses, interest rate, taxes, etc. The output of the LP model yields the minimum total operating cost, optimal sizes of the equipment and their respective operational schedules. The hot utility and cold utility transportation model estimates the economic-minimum pipe size, considering installation cost, heat loss/gain cost and pumping cost. The heat balance model finds the thermal cycle equipment sizes as well as the variation of the heat-to-power ratio with load. Finally the economic model does the cash-flow analysis to determing whether the project will yield a required rate-of-return to be economically viable.

Simulations have been done using the model considering a number of sample load patterns with the prevailing cost factors in India. An after tax IRR of 20% was found for sites having load factors greater than 0·6, and up to 10 km utility transportation distance.     

Characteristics of DC magnetron sputtered ternary cobalt-nickel silicide thin films for ultra shallow junction devices

Ternary cobalt-nickel silicide thin films were synthesized by DC magnetron sputtering from an equiatomic cobalt-nickel alloy target. Grazing incidence XRD, Rutherford back scattering, high-resolution cross-sectional TEM analysis and electrical study were carried out to investigate the formation of silicide, stoichiometry, film thickness, depth profile and sheet resistance of as-deposited and post-deposition annealed films. The ternary silicide layer thickness was calculated from RBS simulated data, which was found to vary 20-43 nm for as-deposited and different vacuum annealed films. A minimum value of sheet resistance 2.73 Ω/sq corresponding to a resistivity of ∼8.4 μΩ-cm was obtained for optimized deposition and annealing conditions.     

Self-Sensing Actuation With Adaptive Control in Applications With Switching Trajectory

This paper presents the application of self-sensing actuation (SSA) to facilitate the implementation of piezoelectric actuator in an intelligent mechatronic system. SSA is a technique to employ smart materials, such as piezoelectric materials, simultaneously as a sensor and an actuator; thereby increasing the level of integration of the system. The piezoelectric actuator is equipped with an exclusive adaptive controller amidst its nonlinearities and system's disturbance. The application area to be discussed is a microdispensing system, which is an example of a micromanufacturing process, combining a fluidic system and a positioning system.     

Doping-Dependent Nonlinear Electron Mobility in GaAs|InxGa1 –xAs Coupled Quantum-Well Pseudo-Morphic MODFET Structure

Semiconductors - We analyze the asymmetric delta-doping dependence of nonlinear electron mobility μ of GaAs|InxGa1 –xAs double quantum-well pseudo-morphic modulation doped field-effect...     

High Performance Lithium‐Ion Batteries Using Layered 2H‐MoTe2 as Anode

The major challenges faced by candidate electrode materials in lithium‐ion batteries (LIBs) include their low electronic and ionic conductivities. 2D van der Waals materials with good electronic conductivity and weak interlayer interaction have been intensively studied in the electrochemical processes involving ion migrations. In particular, molybdenum ditelluride (MoTe₂) has emerged as a new material for energy storage applications. Though 2H‐MoTe₂ with hexagonal semiconducting phase is expected to facilitate more efficient ion insertion/deinsertion than the monoclinic semi‐metallic phase, its application as an anode in LIB has been elusive. Here, 2H‐MoTe₂, prepared by a solid‐state synthesis route, has been employed as an efficient anode with remarkable Li⁺ storage capacity. The as‐prepared 2H‐MoTe₂ electrodes exhibit an initial specific capacity of 432 mAh g^?1 and retain a high reversible specific capacity of 291 mAh g^?1 after 260 cycles at 1.0 A g^?1. Further, a full‐cell prototype is demonstrated by using 2H‐MoTe₂ anode with lithium cobalt oxide cathode, showing a high energy density of 454 Wh kg^?1 (based on the MoTe₂ mass) and capacity retention of 80% over 100 cycles. Synchrotron‐based in situ X‐ray absorption near‐edge structures have revealed the unique lithium reaction pathway and storage mechanism, which is supported by density functional theory based calculations.