Development of transparent and conductive ZnO films by spray pyrolysis

Indium-doped zinc oxide (IZO) films were deposited on Corning 7059 substrates by the spray pyrolysis technique. To achieve higher electrical conductivity both the zinc acetate concentration and indium concentration in the solution were varied. The films were characterized for their structural and electrical properties. Film stability in H₂ plasma was also checked for possible use in amorphous and microcrystalline silicon related fields. It was observed that the films can be sustained in a hydrogen plasma, and hence IZO films of high conductivity can be used for the development of amorphous and microcrystalline silicon solar cells.     

Cell formation using multiple process plans

Cell formation (CF) consists of identifying machine groups and part families. Many CF procedures use a part machine matrix as an input and attempt to obtain a block diagonal form. But perfect block diagonalization of parts and machines is not possible is many cases. In this paper we consider a generalized cellular manufacturing (CM) problem, in which each part can have alternate process plans and each operation can be performed on alternate machines. Under these conditions the CF problem of assigning parts and machines to each manufacturing cell can be considered as a two stage process. The first stage deals with the problem of determining a unique process plan for each part. The second stage determines the part families and machine cells. In this research a model for forming part families and machine cells is presented considering alternate process plans. The objective is to analyze how alternate process plans influence and enhance the CM process giving better flexibility to the designer while designing cells for CM.     

Rare earth cobaltite catalysts: Relation of activity to spin and valence states of cobalt

Catalytic activities of rare earth cobaltites and related compounds are shown to be related to the spin and valence states of cobalt.     

Structured selective coatings

Nickel-impregnated anodized Al₂O₃ films on aluminium substrates were investigated as possible selective coatings for the photothermal conversion of solar energy. A purely chemical dip process for producing these spectrally selective coatings was developed as an alternative to the electrochemical process reported earlier. The process parameters were optimized to give α = 0.92 and ε = 0.19. These coatings are cheap, efficient and durable.X-ray diffraction, scanning electron microscopy and electron spectroscopy for chemical analysis investigations were performed at various stages during the formation of these coatings and their structure was determined from the data obtained. The proposed structure agrees with that reported earlier. Maxwell Garnett theory and the concept of the equivalent homogeneous medium were used to determine the theoretical optical properties of these films as a function of (1) the thickness and porosity of the Al₂O₃ layer and (2) the thickness of nickel deposited in the pores. The optimum values of the theoretical parameters are in good agreement with those determined experimentally.     

Scheduling Algorithms for Star-Coupled WDM Networks with Tunable Transmitter and Tunable Receiver Architecture

This paper presents the design and analysis of two scheduling algorithms for a reservation-based medium access control (MAC) protocol for wavelength division multiplexed (WDM) multi-channel optical networks. The network architecture is based on a passive star topology with one tunable transmitter and receiver (TT-TR) per node. The main objective of scheduling algorithm design is to reduce the computation time while maximizing the utilization of the network resources. In this paper, we propose two scheduling schemes called SEQSAM (SEQuential Scheduling AlgorithM) and BALSAM (BALanced Scheduling AlgorithM). Let M denote the number of nodes, C the number of channels, and K the maximum number of packets transmitted by one node to another. SEQSAM uses the M × M traffic demand matrix--obtained during the reservation phase of the MAC protocol--to compute a collision-free schedule for the nodes of the network. BALSAM uses the modified MULTI-FIT algorithm (MMFT) [1] to convert the M × M matrix into a corresponding M × C matrix, which is input to the IBS (Interval Based Scheduling) algorithm [2] that schedules the requests of the nodes. The overall time complexity of SEQSAM is O(M ³) compared to BALSAM algorithm's time complexity of O(M ² CK + M ² + MlogM). Note that the lower bound for any scheduling algorithm operating on a M × M matrix is O(M ²). A simulation-based performance study that considers network utilization, computation time, tuning latency, average packet latency and throughput for 1.2 Gbps and 2.4 Gbps data streams is presented.