Design of Optimal Linear Precoder and Decoder for MIMO Channels with Per Antenna Power Constraint and Imperfect CSI

This paper addresses the problem of designing joint optimum precoder and decoder for multiple-input multiple-output communication system. Conventionally, most of the joint precoder and decoder designs are based on the sum power constraint (SPC) at the transmitter and perfect channel state information (CSI). However, in practice, per-antenna power constraint is more realistic as the power at each transmit antenna is limited individually by the linearity of the power amplifier. Further, the estimate of CSI cannot be obtained perfectly by any methods. Under imperfect CSI, the aim is to design jointly optimum precoder and decoder subject to a power constraint that jointly meets both per-antenna and SPCs. The objective function is formulated into an optimization problem that minimizes the mean square error in estimating the transmitted signal. The simulation results show that the proposed scheme has a near-optimum performance under practical constraints.     

Experimental Investigation of Mechanical and Morphological Properties of Flax-Glass Fiber Reinforced Hybrid Composite using Finite Element Analysis

The use of cellulosic fibers as reinforcing materials in polymer composites has gained popularity due to an increasing trend for developing sustainable materials. In the present experimental study, flax and glass fiber reinforced partially eco-friendly hybrid composites are fabricated with two different fiber orientations of 0° and 90°. The mechanical properties of these composites such as tensile, flexural and impact strengths have been evaluated. From the experiments, it has been observed that the composites with the 0° fiber orientation can hold the maximum tensile strength of 82.71 MPa, flexural strength of 143.99 MPa, and impact strength of 4 kJ/m². Whereas the composites with 90° fiber orientation can withstand the maximum tensile strength of 75.64 MPa, flexural strength of 134.86 MPa, and impact strength of 3.99 kJ/m². Morphological analysis is carried out to analyze fiber matrix interfaces and the structure of the fractured surfaces by using scanning electron microscopy (SEM). The finite element analysis (FEA) has been carried out to predict the resulting important mechanical properties by using ANSYS 12.0. From the results it is found that the experimental results are very close to the results predicted from FEA model values. It is suggested that these hybrid composites can be used as alternate materials for pure synthetic fiber reinforced polymer composite materials.     

Performance Analysis of Millimeter Wave SWIPT System Using Ginibre Point Process

This paper deals with the coverage probability analysis of mmWave simultaneous wireless information and power transfer (SWIPT) system using stochastic geometry. mmWaves are higher frequency waves results in dense deployment of base stations (BS) leading to a higher data rate. Stochastic geometry provides a mathematical model to the randomly distributed nodes in the network. The Poisson point process (PPP) is the most analytically tractable and widely used model for the location of BSs, but it fails to capture the underlying separation between the BSs of cellular networks. Ginibre point process (GPP) model is used for the repulsion between the two nodes and provides a realistic model compared to PPP. In this paper, mmWave interfering base stations are considered to be GPP for deriving the coverage probability analysis. The proposed model considers the interfering base stations for analyzing the coverage probability. The closed form expression for the coverage probability is derived and is analyzed. The theoretical results are validated through simulation results.

     

Some scaling laws governing gun erosion

Gun barrel erosion is one of the major problems limiting the velocity, range and accuracy of the projectile. The various interacting mechanisms causing erosion are discussed. The importance of developing scaling laws governing gun tube erosion is emphasized. The approach adopted in this paper for the development of scaling laws is inspired by similar attempts in cavitation and liquid impact erosion. The concepts of threshold erosion, erosion intensity, erosion strength and erosion parameter are extended, modified and applied to gun tube erosion. As a result, the outlook for developing scaling laws governing gun barrel erosion seems very promising. The nondimensional number called the erosion parameter is given by the ratio between the output intensity of erosion representing the energy absorbed by the material and the input intensity of erosion contributed by the erosive forces. The output intensity of erosion is given by the product of the rate of depth of erosion and erosion resistance of the material, whereas the input intensity includes the Poisson's ratio of the projectile, the maximum acceleration, the maximum velocity and the bore diameter. With the aid of a few justifiable assumptions, it has been shown that the rate of depth of erosion is directly proportional to the square of the bore diameter. Available experimental data support these results for velocity scale and size scale. Further experiments are required to test these predictions fully. The erosion state is highly dependent on the number of rounds fired; it has four stages including incubation, acceleration, deceleration and steady state periods very similar to other erosion phenomena. Previously developed erosion theory correlates well with the available gun tube erosion rates as a function of the number of rounds fired; this lends further support to the erosion model proposed in this paper. However, the interacting influences of thermal and chemical mechanisms must be carefully considered in any further developments.     

Evaluation of Fat Uptake of Polysaccharide Coatings on Deep-Fat Fried Potato Chips by Confocal Laser Scanning Microscopy

In the present investigation, potato slices of 3 cm diameter and 1.5 mm thickness with edible coating (1% Okra and 1% Okra + Carrageen polysaccharide coating solutions) and without any coating treatment (control samples) were fried in sunflower oil at temperatures from 170–180°C for 5 min. Confocal laser scanning microscopy of fried chips was recorded using fluorescence mode of the microscope. We observed gas cells and fat globules in the confocal laser scanning microscopy micrographs of fried chips. The results indicated that both 1% Okra and 1% Okra + Carrageen polysaccharide were effective in reducing the moisture loss and decreasing oil uptake (p ≤ 0.05), but we found the highest effect in those samples treated with 1% Okra + Carrageen polysaccharide coating. These results substantiate the application of edible coating with 1% Okra and 1% Okra + Carrageen polysaccharide to the potato chips resulting in better moisture retention capacity, eventually leading to chips with lower fat content.     

Significance of chemical conditioning to improve dewaterability of biosludge generated from tanneries

To improve the dewaterability, biosludge generated from activated sludge process and membrane bioreactor operated for treatment of tannery wastewater was conditioned with Fenton’s reagent alone and Fenton’s reagent in conjunction with polyelectrolyte, respectively. Studies were carried out at an optimum pH of 3.0 with a fixed Fe²⁺ concentration of 3,000 mg/L. Hydrogen peroxide and polyelectrolyte dosages were varied for the sludge generated from membrane bioreactor and activated sludge process. Optimum dosages were ascertained for hydrogen peroxide and polyelectrolyte. Hydrogen peroxide dosage of 900 and 750 mg/L were observed as optimum for membrane bioreactor sludge and activated process sludge with respect to volume of settled sludge. Polyelectrolyte dosage of 7.5 mg/L for membrane bioreactor sludge and 5 mg/L for activated process sludge in conjunction with Fenton’s reagent was found to be the optimum with respect to volume of settled sludge. For the optimum dosage of Fenton’s reagent in conjunction with polyelectrolyte, results were compared with respect to capillary suction time and release of bound water.     

An improved three-dimensional direct numerical modelling and thermal analysis of a female breast with tumour

It is well known that malignant tumour tissue generally has higher metabolic and blood perfusion rates than most normal tissues. The authors aim to show that the tissue temperature profile within the breast and the surface temperature profile can be quantified to develop an expert system or diagnostic tool for breast cancer detection. The surface temperature and tissue temperature profiles are analysed for a three-dimensional numerical model of a normal breast and a breast with a tumour. Tumours of different sizes are placed at various locations. In the model, the tissue temperature profile is distorted at the tumour location and was found to compare well with in vivo tests. It was also found that as the tumour was moved to deeper locations its effect on surface temperature was lower. It was observed that small tumours in deeper regions do not have a significant isolated impact on the surface. The numerical results could also capture a shift in the position of the tumour. For tumours greater than 10 mm in the superficial regions and of significant size in deeper regions, it could be seen that the surface temperature distribution of the breast is directly related to the position and size of the tumour embedded in it. The feasibility of providing a diagnostic tool in conjunction with numerical modelling and high-resolution thermograms is also discussed.     

DPM dissipation experiment at MST’s experimental mine and comparison with CFD simulation

Diesel Particulate Matter (DPM) is regulated in the U.S. for both underground coal and metal/nonmetal mines. Today, many underground mines still face difficulty in compliance with DPM regulations. The DPM research carried out in Missouri University of Science and Technology (MST) is to use computational fluid dynamics (CFD) to study the DPM distribution in commonly used face areas. The result is expected to be used for selection of DPM reduction strategies and better working practices, which can help the underground mines to meet regulation limits and improve the working environment for the miners. An experiment was conducted at MST’s Experimental Mine to validate CFD simulation. DPM was collected at four locations downstream of a stationary diesel engine. The experiment data were then compared with the CFD simulation results. The comparison shows that CFD simulation can forecast the location of DPM concentration with practical accuracy (less than 0.15 m). CFD can be used to further study DPM distribution in commonly used working faces and give guidance to DPM reduction.