Modified Multiple Feedback QR Aided Successive Interference Cancellation Algorithm for Large MIMO Detection

Wireless Personal Communications - Multiple-input multiple-output (MIMO) systems have attracted increased interest due to their capability to achieve higher multiplexing and diversity gains. In...     

Band-Notched Planar UWB Microstrip Antenna with T-Shaped Slot

Ever growing demand for higher data rates requires appropriate radiation systems with large bandwidth and stable gain. Microstrip antennas with unidirectional radiation patterns and stable gain are most useful for this purpose. A ground plane defect of microstrip patch antenna is used to breed multiband applications. As a result, the performance of gain, directivity, and bandwidth is enhanced, the geometry and shape of an ultrawideband (UWB) antenna are simplified, and its size is reduced. Thus, it results in the efficient performance with respect to wideband operation. A novel band notching of microstrip truncated UWB antenna is implemented for insusceptibility in the range 5.2–5.8 GHz. The suggested structure contains circular truncated and T-shaped slots for band notching. The optimal results can be obtained by selecting the antenna parameters. Advantages of the proposed antenna include small size, better impedance match and simple design. Details of the suggested and observational solutions are demonstrated in this paper. The S₁₁ parameter of antenna is–45.5 dB at a resonant frequency of 4.6, 5.5, and 9.8 GHz. The gain of antenna is 5.47 dB, and the value of VSWR is smaller than 2, which makes the proposed structure an ideal choice for its application in wireless communication, 5G and IoT.     

Performance analysis of MIMO–OFDM free space optical communication system with low-density parity-check code

In this paper, we have evaluated the performance of a low-density parity-check (LDPC)-coded multiple-input multiple-output (MIMO) orthogonal frequency division multiplexing (OFDM) free space optical (FSO) communication system. Closed form expressions for the average bit error rate and throughput with diversity using equal gain combining have been obtained for the system under consideration. The Monte Carlo simulation has been carried out for the verification of the results. The performance of the QPSK and 16 QAM modulations is evaluated for different weather and atmospheric turbulence conditions. The results are also compared for both, QPSK and 16 QAM for SISO–OFDM, \(2\times 2\) and \(4 \times 4\) MIMO–OFDM FSO communication system. The results show that the performance of the system under consideration improves, as we move from SISO–OFDM to \(4 \times 4\) MIMO–OFDM. The results also show that the effect of weather is very much pronounced on the system and the performance in terms of average bit error rate of QPSK is better than 16 QAM in the presence of every weather condition. However, the later provides better throughput. Regular LDPC codes with code rate 1/2 have been applied to the simulated results, yielding high coding gains. Coding gain of 29.5 and 22 dB is achieved for QPSK and 16 QAM, respectively, for \(4 \times 4\) MIMO–OFDM.     

Optimal protein library design using recombination or point mutations based on sequence-based scoring functions

In this paper, we introduce and test two new sequence-based protein scoring systems (i.e. S1, S2) for assessing the likelihood that a given protein hybrid will be functional. By binning together amino acids with similar properties (i.e. volume, hydrophobicity and charge) the scoring systems S1 and S2 allow for the quantification of the severity of mismatched interactions in the hybrids. The S2 scoring system is found to be able to significantly functionally enrich a cytochrome P450 library over other scoring methods. Given this scoring base, we subsequently constructed two separate optimization formulations (i.e. OPTCOMB and OPTOLIGO) for optimally designing protein combinatorial libraries involving recombination or mutations, respectively. Notably, two separate versions of OPTCOMB are generated (i.e. model M1, M2) with the latter allowing for position-dependent parental fragment skipping. Computational benchmarking results demonstrate the efficacy of models OPTCOMB and OPTOLIGO to generate high scoring libraries of a prespecified size.     

Dynamics of impact of sphere on flat surfaces of polymer matrix composites

The primary objective of this work was to evaluate the influence of various reinforcements and matrix materials on the dynamic hardness of polymer matrix materials (PMC). Therefore, the impact of a WC ball, using a gravity drop system, was studied on PMCs. The two parameters, coefficient of restitution and dynamic hardness, of PMCs were determined. The mechanical properties of the PMCs were evaluated, and the correlation of the two parameters with the mechanical properties of PMCs was attempted.     

Insights into the Genetic Variations of Human Cytochrome P450 2C9: Structural Analysis,Characterization and Comparison

Cytochromes P450 (CYP) are one of the major xenobiotic metabolizing enzymes with increasing importance in pharmacogenetics. The CYP2C9 enzyme is responsible for the metabolism of a wide range of clinical drugs. More than sixty genetic variations have been identified in CYP2C9 with many demonstrating reduced activity compared to the wild-type (WT) enzyme. The CYP2C9*8 allele is predominantly found in persons of African ancestry and results in altered clearance of several drug substrates of CYP2C9. The X-ray crystal structure of CYP2C9*8, which represents an amino acid variation from arginine to histidine at position 150 (R150H), was solved in complex with losartan. The overall conformation of the CYP2C9*8-losartan complex was similar to the previously solved complex with wild type (WT) protein, but it differs in the occupancy of losartan. One molecule of losartan was bound in the active site and another on the surface in an identical orientation to that observed in the WT complex. However, unlike the WT structure, the losartan in the access channel was not observed in the *8 complex. Furthermore, isothermal titration calorimetry studies illustrated weaker binding of losartan to *8 compared to WT. Interestingly, the CYP2C9*8 interaction with losartan was not as weak as the CYP2C9*3 variant, which showed up to three-fold weaker average dissociation constant compared to the WT. Taken together, the structural and solution characterization yields insights into the similarities and differences of losartan binding to CYP2C9 variants and provides a useful framework for probing the role of amino acid substitution and substrate dependent activity.     

Studies on the curing kinetics and thermal stability of the novel tetrafunctional epoxy resin N,N,N′N′-tetrakis(2,3-epoxypropyl)-4,4′-(1,4-phenylenedioxy)dianiline

A novel tetrafunctional epoxy resin, namely N,N,N′N′-tetrakis(2,3-epoxypropyl)-4,4′-(1,4-phenylenedioxy)dianiline, has been synthesized. The curing kinetics has been studied by differential scanning calorimetry (DSC) using various amine curing agents. Thermal stabilities of the cured products have been investigated by thermogravimetric (TG) analyses. The overall activation energies for the curing reactions are observed to be in the range 63.6–196.7 kJ·mol^–1. The cured products have good thermal stability.     

Temperature stability and bioadhesive properties of delta9-tetrahydrocannabinol incorporated hydroxypropylcellulose polymer matrix systems

The purpose of this study was to determine and compare the bioadhesive profiles of hydroxypropylcellulose (HPC) polymer matrices as a function of Δ⁹-tetrahydrocannabinol (THC) content. In addition, the effect of processing temperature on the stability of THC and its extent of degradation to cannabinol (CBN) was investigated. A hot-melt cast molding method was used to prepare HPC polymer matrix systems incorporated with THC at 0, 4, 8, and 16 percent. Bioadhesive measurements including peak adhesive force, area under the curve, and elongation at adhesive failure were recorded utilizing the TA.XT2i Texture Analyzer^™. Data obtained from these tests at various contact time intervals suggested that the incorporation of THC led to an increase in the bioadhesive strength of the HPC polymer matrices. To determine the stability of THC and the resulting CBN content in the matrices, three different processing temperatures were utilized (120, 160, and 200°C). Post-production High Performance Liquid Chromotography (HPLC) analysis revealed that the processed systems contained at least 94% of THC and the relative percent formation of CBN was 0.5% at 120°C and 0.4% at 160°C compared to 1.6% at 200°C. These findings indicate that the cannabinoid may be a plausible candidate for incorporation into systems utilizing hot-melt extrusion techniques for the development of an effective mucoadhesive transmucosal matrix system for delivery of THC.     

On the significance of developing boundary layers in integrated water cooled 3D chip stacks

We present in this paper a fundamental hydrothermal investigation of the next generation interlayer integrated water cooled three-dimensional (3D) chip stacks, with high volumetric heat generation. Such investigation of flow through microcavities with embedded heat transfer structures such as micro pin-fin arrays and microchannels is crucial for the successful realization of 3D chip stacks. We focus mainly on the complex physics of the entrance region of the cooling microcavities in order to assess its importance. The flow and heat transfer in the entrance region is strongly influenced by developing boundary layers and, as we show herein, the development lengths can occupy a significant portion of the microcavity due to the size restrictions of the 3D chip stack. These effects make a fundamental understanding of conjugate heat transfer in microcavities with heat transfer structures a necessity. The flow field and heat transfer in the entrance region are characterized by means of correlations determining the effective coolant permeability as well as the heat transfer coefficient as a function of the streamwise coordinate x, the flow Reynolds number (Re) and the Prandtl number. Based on a thermal non-equilibrium porous medium model relying on these results, a substantially improved estimation of pressure drop and temperature distribution inside the chip stack is realized. The modeling results are validated against measurements on a 3D chip stack simulator. The range of flow rates and thermal loads in the hot spots of the chip stack, over which it is crucial to consider the developing hydrothermal effects, are analyzed and discussed in detail. Moreover, microchannel and micro pin-fin structures are compared, showing more than 20% increased performance of the latter for all operating conditions investigated.     

Hot water cooled electronics: Exergy analysis and waste heat reuse feasibility

We report an experimental study on exergetically efficient electronics cooling using hot water as coolant. It is shown that water temperatures as high as 60 °C are sufficient to cool microprocessors with over 90% first law (energy based) efficiency. The chip used in our experiment is kept at temperatures of 80 °C or below so as not to exceed any allowable industrial specifications for maximum microprocessor chip temperature. The use of hot water as coolant will eliminate the requirement for chillers typically used in air-cooled data centers and, therefore, significantly reduce the power consumption. An exergy analysis shows that a six fold rise in second law (exergy based) efficiency is achieved by switching the water inlet temperature from 30 °C to 60 °C. The resulting high exergy at the heat sink outlet is a measure of the potential usefulness of the waste heat of data centers, thereby helping to design data centers with minimal carbon footprint. A new metric for the economic value of the recovered heat, based on costs for electricity and fossil fuels, heat recovery efficiency and an application specific utility function, is introduced to underscore the benefits of hot water cooling. This new concept shows that the economic value of the heat recovered from data centers can be much higher than its thermodynamic value.