Performance of coded DS‐CDMA system using reduced rank MMSE receiver in Rayleigh fading channels

This paper examines the performance of a reduced rank minimum mean square error (MMSE) receiver‐based direct sequence code division multiple access (DS‐CDMA) system. For such system, when a large processing gain is employed, substantial time is consumed in computing the filter tap weights. Many schemes for reducing the complexity of the MMSE have been proposed in recent years. In this paper, computational complexity reduction of the MMSE receiver is achieved by using the K‐mean classification algorithm. The performance of the uncoded and coded systems are investigated for the full rank MMSE receiver and reduced rank MMSE receiver and results are compared in terms of bit error rate at different loading levels in both AWGN and fading channels. A system with the matched filter (MF) receiver is also presented for the purpose of comparison and an analytical pair‐wise error bound for the coded system is derived. In the adaptive implementation of the receivers, results show that good performance is achieved for the reduced rank receiver when compared to the full rank receiver in both coded and uncoded systems, while in the optimum implementation of the tap weights, the reduced dimension receiver performance experiences degradation when compared to the full rank scheme. Over the band‐limited channels considered, results for the reduced rank receiver also reiterate the fact that higher code rates tend to yield lower BER than that of low rate codes. Copyright © 2006 John Wiley & Sons, Ltd.     

Thermal performance analysis of gas turbine engines based on different compressor configurations

In this study, the performance of several gas turbine engines has been investigated using computational modelling based on the actual manufacturer's data. Further, the study focuses on evaluating the impact of varying the configuration of the compressor on overall engine performance based on the first and second laws of thermodynamics. The results confirm that the main source of irreversibilities occurs in the combustion chamber in all cases. The exergetic efficiency of the gas turbine engine significantly varies with compressor configurations, type of compressors, load variation, climatic condition, and isentropic efficiency. The engine capacity and high‐pressure turbine inlet temperature govern the gas turbine performance, and higher values are more favourable. The gas turbine exergetic efficiency drops off when the power setting adjusted at part‐load and at high ambient temperature. The most optimal gas turbine performance is located at the single axial compressor case, followed by the axial‐centrifugal compressor and then the centrifugal–centrifugal compressor.     

Retracted: Resveratrol Derivative,Trans-3, 5, 4′-Trimethoxystilbene,Prevents the Developing of Atherosclerotic Lesions and Attenuates Cholesterol Accumulation in Macrophage Foam Cells

Mol. Nutr. Food Res.2020, 64, 1 901 115 https://doi.org/10.1002/mnfr.201901115 . The above article, published online on 22 January 2020, in Wiley Online Library (wileyonlinelibrary.com), has been retracted by agreement between the journal's Editor-in-Chief, Dr. Julia Reuter, and Wiley-VCH GmbH. Following publication, the journal was contacted by the University of Kansas who indicated that three of the co-authors, Jinke Li, Siying Li and Mohammed M. Almutairi, whose affiliations had been noted at the Department of Pharmacology & Toxicology, University of Kansas, were not affiliated with the university. In addition, the journal was made aware of concerns raised by third parties regarding this article which evidences image duplication between Figures 1, 2, 3, 4, 6, and 7, and Table 1 in this article and two other articles purporting to show different data. The authors were contacted to ask for their explanation of the concerns raised, but no response was received. The retraction has been agreed as the editorial team no longer have confidence in the reported results and conclusions given the significant overlap between the results reported in the Figures and other published articles.     

Resistive-switching in yttria-stabilized hafnia ceramics

Yttria-stabilized hafnia ceramics are high-temperature oxide ion conductors that lose a small amount of oxygen, both at high temperatures and on the application of a small dc bias. At zero applied bias, a small amount of p-type conductivity is present. This increases with low bias and is attributed to reactions initiated at the positive electrode/ceramic interface. With a further increase in bias, n-type conductivity is initiated at the negative electrode/ceramic interface. After a short time-lapse, the overall conductivity increases rapidly by 1.5–3 orders of magnitude and is reversible, with hysteresis, on subsequent removal of the bias. Switching has been observed over the range 457–531°C and is sensitive to both temperature and oxygen partial pressure in the surrounding atmosphere. This is the first example of low field, resistive switching in bulk hafnia ceramics, in contrast to most examples of resistive switching which are observed in nanometre-thick devices using similarly applied voltages.     

Graphitic Carbon Nitride Decorated with Iron Oxide Nanoparticles as a Novel High-Performance Biomimetic Electrochemical Sensing Platform for Paracetamol Detection

Design and development of new generation smart sensors for medical applications have gained considerable interest of research community in the recent past. In this work, we propose the fabrication of highly sensitive paracetamol sensors-based iron oxide nanoparticles intercalated with graphitic carbon nitride (g-C₃N₄) (GCN) via insitu chemical synthesis. Structural features of the composites were analyzed through SEM, EDX, XRD, FTIR, and UV-Visible spectroscopic techniques. Presence of iron oxide nanoparticles in GCN, significantly improved the conductivity bare GCN from 16 to 125 S cm^?1 due to extended π–π conjugation and large surface area in the composite system. The GCN-Iron oxide (GCN-FO) nanocomposite has been employed as an electrochemical sensing platform for non-enzymatic detection of paracetamol. The electrochemical studies and cyclic voltammetry (CV) results shows that the GCN-FO composite exhibit superior electrochemical properties due to their lower values of the oxidation and reduction potentials. Electrochemical impedance spectroscopy (EIS) studies indicate decreased charge-transfer resistance for iron oxide doped GCN composite in compare to base GCN. The improved electrochemical sensing performance of modified GCN-FO composite electrode is attributed to the formation heterojunctions between iron oxide nanoparticles and GCN. The modified GCN-FO electrodes were employed for non-enzymatic electrochemical detection of PR. The GCN-FO composite electrode shows excellent sensitivity towards PR with a LOD 0.3 μM. Furthermore, the modified GCN-FO electrodes show excellent reproducibility, selectivity, stability and anti-interference performance. Due to its low-cost fabrication, superior electrochemical sensing performance, these modified GCN-FO electrodes could be a promising material for the detection of paracetamol at low concentrations.

     

Sparrow Search Optimization with Transfer Learning-Based Crowd Density Classification

Due to the rapid increase in urbanization and population, crowd gatherings are frequently observed in the form of concerts, political, and religious meetings. HAJJ is one of the well-known crowding events that takes place every year in Makkah, Saudi Arabia. Crowd density estimation and crowd monitoring are significant research areas in Artificial Intelligence (AI) applications. The current research study develops a new Sparrow Search Optimization with Deep Transfer Learning based Crowd Density Detection and Classification (SSODTL-CD2C) model. The presented SSODTL-CD2C technique majorly focuses on the identification and classification of crowd densities. To attain this, SSODTL-CD2C technique exploits Oppositional Salp Swarm Optimization Algorithm (OSSA) with EfficientNet model to derive the feature vectors. At the same time, Stacked Sparse Auto Encoder (SSAE) model is utilized for the classification of crowd densities. Finally, SSO algorithm is employed for optimal fine-tuning of the parameters involved in SSAE mechanism. The performance of the proposed SSODTL-CD2C technique was validated using a dataset with four different kinds of crowd densities. The obtained results demonstrated that the proposed SSODTL-CD2C methodology accomplished an excellent crowd classification performance with a maximum accuracy of 93.25%. So, the proposed method will be highly helpful in managing HAJJ and other crowded events.     

The Correlation of Device Parameters with Illumination Energy to Explore the Performance of a Monocrystalline Silicon Solar Module

Silicon - The effect of illumination energy on the electrical parameters of a monocrystalline silicon solar module was investigated and results used to reveal the effective spectrum which can help...     

Hill Matrix and Radix-64 Bit Algorithm to Preserve Data Confidentiality

There are many cloud data security techniques and algorithms available that can be used to detect attacks on cloud data, but these techniques and algorithms cannot be used to protect data from an attacker. Cloud cryptography is the best way to transmit data in a secure and reliable format. Various researchers have developed various mechanisms to transfer data securely, which can convert data from readable to unreadable, but these algorithms are not sufficient to provide complete data security. Each algorithm has some data security issues. If some effective data protection techniques are used, the attacker will not be able to decipher the encrypted data, and even if the attacker tries to tamper with the data, the attacker will not have access to the original data. In this paper, various data security techniques are developed, which can be used to protect the data from attackers completely. First, a customized American Standard Code for Information Interchange (ASCII) table is developed. The value of each Index is defined in a customized ASCII table. When an attacker tries to decrypt the data, the attacker always tries to apply the predefined ASCII table on the Ciphertext, which in a way, can be helpful for the attacker to decrypt the data. After that, a radix 64-bit encryption mechanism is used, with the help of which the number of cipher data is doubled from the original data. When the number of cipher values is double the original data, the attacker tries to decrypt each value. Instead of getting the original data, the attacker gets such data that has no relation to the original data. After that, a Hill Matrix algorithm is created, with the help of which a key is generated that is used in the exact plain text for which it is created, and this Key cannot be used in any other plain text. The boundaries of each Hill text work up to that text. The techniques used in this paper are compared with those used in various papers and discussed that how far the current algorithm is better than all other algorithms. Then, the Kasiski test is used to verify the validity of the proposed algorithm and found that, if the proposed algorithm is used for data encryption, so an attacker cannot break the proposed algorithm security using any technique or algorithm.     

Glass transition,topology, and elastic models of Se-based glasses

Features intrinsic to disorder and network aspects are ubiquitous in structural glasses. Among this important class of materials, chalcogenide glasses are special—they are built of short-range covalent forces, making them simpler than silicate glasses that possess mixed ionic and covalent forces. Selenium-based glasses also display complex elastic phase transitions that have been described from various models, including mean-field approaches to molecular simulations. These point to the presence of two sharply defined elastic phase transitions, a rigidity and stress transition that are non-mean-field in character, and separate the three distinct topological phases of flexible, isostatically rigid, and stressed-rigid. This article reviews the physics of these glassy networks. The elastic phases and glass transition temperature are explained on a molecular level in terms of topological constraint theory (TCT), connectivity, and the open degrees of freedom. The broader aspects of TCT in relation to phase change materials, high-k dielectrics, and cements are also commented upon.