An iterative technique for fitting exponentials

An interative method to fit the function \documentclass{article}\pagestyle{empty}\begin{document}$\mathop \[y = \sum\nolimits_i^n { = 1} a_i e^{lix}\] $\end{document} to data is considered. The technique used is that of inversion of a linear differential operator with constant coefficients. This method reproduces the parameters for mathematically precise data and gives satisfactory results when the data are affected by random errors.     

Wear of grinding wheels

Wear phenomena accompanying cylindrical grinding were investigated directly from the wear particles removed from the wheel. The self-dressing mechanism was identified from the wear particle size distribution.     

Design data for solar heating of air Using a Heat Exchange and Storage System

An arrangement for heating with solar energy by means of a heat exchanger and storage coupled to the two water heaters has been described^*. In the present paper, the amount of the heat transferred from water to air in the shell-and-tube heat exchanger and the temperature of the outgoing air have been estimated by considering various parameters, viz. flow rate and temperature of incoming air, temperature of incoming and outgoing water, length and diameter of tubes, etc. Both natural and forced convection mode of heat transfer have been considered.

Under boundary conditions of free convection, heat transfer would be rapid and efficient with a possible reduction in the pipe length. The maximum permissible limit of pressure drop per foot of each tube for pipes of different diameters at different Reynolds numbers has been given.

As conditions of drying vary from material to material, the data presented will help in arriving at the final design of the shell-and-tube heat exchanger to be used in drying a particular material.     

From Experience with Indoor Wireless Networks: A Link Quality Metric that Captures Channel Memory

With ARQ based link-layer schemes, energy consumption on a link increases with packet retransmissions. We define the inefficiency of a link as the expected number of transmissions before a packet is successfully received on that link. Memory in the packet success process, caused by long indoor coherence times, strongly influences inefficiency. Based on measurements, we build a simple model for the packet success process that incorporates memory and predicts our metric practically and accurately. In particular, inefficiency is asymptotically linear in the memory duration when there is a nonzero probability of a deep fade, and approximately logarithmic otherwise.     

Pareto-optimal clustering scheme using data aggregation for wireless sensor networks

The presence of cluster heads (CHs) in a clustered wireless sensor network (WSN) leads to improved data aggregation and enhanced network lifetime. Thus, the selection of appropriate CHs in WSNs is a challenging task, which needs to be addressed. A multicriterion decision-making approach for the selection of CHs is presented using Pareto-optimal theory and technique for order preference by similarity to ideal solution (TOPSIS) methods. CHs are selected using three criteria including energy, cluster density and distance from the sink. The overall network lifetime in this method with 50% data aggregation after simulations is 81% higher than that of distributed hierarchical agglomerative clustering in similar environment and with same set of parameters. Optimum number of clusters is estimated using TOPSIS technique and found to be 9–11 for effective energy usage in WSNs.     

Development of MMIC-based modules for multichannel RF/opticalsubcarrier multiplexed communications applications

We present a C-band monolithic microwave integrated circuit (MMIC) transmitter module development for multichannel RF/optical subcarrier multiplexed (OSCM) communication applications. The C-band MMIC transmitter module consists of one fully monolithic four-channel OSCM transmitter IC and four coupled-line filters. This MMIC is designed and implemented in a commercial GaAs MESFET process and coupled line bandpass filters are fabricated on the module board. We present the design and performance of the first fully monolithic IC transmitter module for OSCM packet switched applications     

An Experimental Evaluation of Link Outage Due to Beam Wander in a Turbulent FSO Link

Wireless Personal Communications - Wireless communication using free space optics (FSO) is becoming attractive for data transmission purposes. However, the system performance gets affected by...     

The design and implementation of a low-power clock-poweredmicroprocessor

We describe the design and implementation of a 16-bit clock-powered microprocessor that dissipates only 2.9 mW at 15.8 MHz based on laboratory measurements. Clock-powered logic (CPL) has been developed as a new approach for designing and building low-power VLSI systems that exploit the benefits of supply-voltage-scaled static CMOS and energy-recovery CMOS techniques. In CPL, the clock signals are a source of ac power for the other large on-chip capacitive loads. Clock amplitude and waveform shape combine to reduce power. By exploiting energy recovery and an energy-conserving clock driver, it is possible to build ultra-low-power CMOS processors with this approach. We compare the CPL approach with a conventional, fully dissipative approach for a processor with a similar ISA and VLSI architecture which was designed using the same set of VLSI CAD tools. The simulation results indicate that the CPL microprocessor would dissipate 40% less power than the conventional design     

Secure and Privacy-Preserving RFID Authentication Scheme for Internet of Things Applications

Wireless Personal Communications - Privacy issue has become a crucial concern in internet of things (IoT) applications ranging from home appliances to vehicular networks. RFID system has found...