Peak-Average-Power Ratio Techniques for 5G Waveforms Using D-SLM and D-PTS

Multicarrier Waveform (MCW) has several advantages and plays a very important role in cellular systems. Fifth generation (5G) MCW such as Non-Orthogonal Multiple Access (NOMA) and Filter Bank Multicarrier (FBMC) are thought to be important in 5G implementation. High Peak to Average Power Ratio (PAPR) is seen as a serious concern in MCW since it reduces the efficiency of amplifier use in the user devices. The paper presents a novel Divergence Selective Mapping (DSLM) and Divergence Partial Transmission Sequence (D-PTS) for 5G waveforms. It is seen that the proposed D-SLM and PTS lower PAPR with low computational complexity. The work highlighted a combination of multi-data block partial transmit schemes along with tone reservation. In this, an overlapping factor is used to determine the number of data blocks for every group. Here, considering only those data blocks that have minimum signal power, the use of DSLM and DPTS are required to eliminate the segment’s peaks. Simulation results reveal that the suggested hybrid technique proves to be better than the conventional PTS scheme. Furthermore, the power saving performance of FBMC and NOMA is compared with the Orthogonal Frequency Division Multiplexing (OFDM) waveform.     

Recovery of potash values from feldspar

ABSTRACT

India does not possess any soluble potassium (K) sources but an abundant resource of alumino-silicate rock such as feldspar is available. In the present work, an attempt has been made to unlock the potassium values from feldspar sample by mechanical milling, roasting and leaching and delineating the underlying mineral phase changes. CaCl₂ was found to be effective flux for K release with valuable by-products such as quartz and anorthite. The roasting kinetics follows the product layer diffusion model with an activation energy of 49.50 kJ/mol. It is found that the planetary ball milling has a significant effect on enhancing K-dissolution. With the combination of different treatments, it is possible to recover more than 95% K from feldspar.     

Effects of external reflector and glass cover cooling on thermo-enviro-economic performance of a stepped solar still

In the current research work, performance enhancement of stepped solar still (SSS) having an external reflector (ER) and glass cover cooling (GCC) arrangements is presented. The individual and combined effects of ER and GCC on the performance of SSS have been evaluated and compared with simple SSS. The GCC reduces the glazing temperature significantly and results in increased distillate. The ER reflected the solar radiation inside the basin that increases the water temperature, consequently increasing distillate. The SSS having ER and GCC (SSS-ER-GCC) gave a maximum distillate of 4.340 kg/m² which was observed, respectively, 12.43%, 3.21%, and 1.36% higher than that of simple SSS, SSS with ER (SSS-ER) and SSS with GCC (SSS-GCC). The average energy efficiency of SSS-ER-GCC was evaluated as 40.78%, which was found to be 14.36%, 7.84%, and 10.64%, respectively, higher than that of simple SSS, SSS-ER, and SSS-GCC. The carbon credits earned and CO₂ mitigation were found the maximum for SSS-ER-GCC having values $65.96 and 4.40 tons, respectively. The economic payback period was found the minimum (490 days) for SSS-ER-GCC.     

Productivity amelioration of stepped solar still using phase change material and evacuated tube collector

This study investigates the individual and cumulative effects of phase change material (PCM) and evacuated tube collector (ETC) on the performance of a stepped solar still (SSS). Experiments have been performed on SSS, SSS loaded with PCM (SSS-PCM), SSS coupled with ETC (SSS-ETC), and SSS loaded with PCM and coupled with ETC (SSS-PCM-ETC). An innovative way of loading paraffin wax as PCM is introduced to utilize solar energy efficiently for the distillation process during off-sunshine hours. ETC is used to provide pre-heated RO wastewater to the distillation unit. The distillate output was observed maximum for SSS-PCM-ETC (4.97 kg/m² day) which is 99% more than that of the SSS unit. The PCM and ETC individually with SSS unit increases the distillate output by 31% and 24%, respectively. The working time of the distillation unit was observed to be increased by 3 h by the use of PCM. The total heat transfer coefficient was evaluated at the maximum for SSS-PCM-ETC and was observed in the range of 16.94–167.04 W/m² °C. The thermal energy efficiencies of SSS, SSS-ETC, SSS-PCM, and SSS-PCM-ETC were evaluated as 28.65%, 35.59%, 43.88%, and 44.04%, respectively. SSS-PCM-ETC is found to be the most economic with the best environmental conservation having maximum values of daily productive cost ($0.69) and carbon credits earned ($184.8).     

Mechanism of selenium sorption by activated carbon

Selenium, along with mercury and halides, represents one of the most volatile trace metallic emissions from coal‐fired combustors and utility boilers. This study investigates the potential of activated carbon in capturing gas phase selenium species in the low temperature range (125°C to 250°C) and elucidates the mechanism of interaction between selenium species and activated carbon. Selenium dioxide is chosen as the representative selenium species and experimental investigations are carried out in a differential bed reactor to illustrate the mechanism of SeO₂ and carbon Interaction, Activated carbons with different structural properties are studied as adsorbents for selenium dioxide capture at low temperature. The capture mechanism is found to involve both physical and chemical adsorption in the low temperature range. At 125°C, about 1.5 wt% of selenium is captured at equillbrium. Carbon surface analyses and XPS studies confirm the presence of both elemental and oxide forms of selenium on the surface suggesting partial reduction of selenium dioxide to elemental selenium at carbon surface.     

Tiled ChrI RHS collection: a pilot high‐throughput screening tool for identification of allelic variants

Reciprocal hemizygosity analysis is a genetic technique that allows phenotypic determination of the allelic effects of a gene in a genetically uniform background. Expanding this single gene technique to generate a genome‐wide collection is termed as reciprocal hemizygosity scanning (RHS). The RHS collection should circumvent the need for linkage mapping and provide the power to identify all possible allelic variants for a given phenotype. However, the published RHS collections based on the existing genome‐wide haploid deletion library reported a high rate of false positives. In this study, we report de novo construction of a RHS collection that is not based on the yeast deletion library. This collection has been constructed for the shortest yeast chromosome, ChrI. Using this ChrI RHS collection, we identified 13 allelic variants for the previously mapped loci and novel allelic variants for the growth differences in different environments. A few of these novel variants, which were fine mapped to a gene level, identified novel genetic variation for the previously studied environmental conditions. The availability of a genome‐wide RHS collection would thus help us uncover a comprehensive list of allelic variants and better our understanding of the molecular pathways modulating a quantitative trait. Copyright © 2014 John Wiley & Sons, Ltd.     

Crack interaction study in piezoelectric materials under thermo-electro-mechanical loading environment

Multiple voids and cracks were generated during material processing techniques, which interact with each other and affects the service performance of piezoelectric components. This work aims to study the behavior of piezoelectric components in presence of multiple cracks under thermo-electro-mechanical loading environment. Extended finite element method has been implemented to model geometrical discontinuities with crack interaction phenomenon. In this work, thermo-electro- mechanical problem has been decoupled into thermal and electro-elastic problems. Temperature distribution has been obtained by solving heat conduction equation and then used as an input to the electro-elastic problem. In post processing phase, interaction integral method and generalized Stroh formalism were used to predict the stress intensity factors. The methodology has been implemented with in-house developed MATLAB code. Set of cases for crack interaction studies were presented using the proposed approach.

     

Transistor size optimization in digital circuits using ant colony optimization for continuous domain

In this paper, ant colony optimization (ACO) algorithm is presented, as a tool to find transistor sizes in digital circuits. Performance of ACO has been tested on four digital circuits, of different complexity, to find optimum balance between power and delay of circuits. Optimization problem has been set up by first, formulating an objective function, to be minimized, for each circuit and then finding the values of variables of circuits, using optimization algorithm. For the purpose of examining the results, circuits are optimized using genetic algorithm (GA) also. Results show that, ACO performs better than GA, for all the four circuits, in finding optimized transistor sizes. Copyright © 2012 John Wiley & Sons, Ltd.