Security aware hybrid precoding based peak‐to‐average power ratio reduction Approaches for telecommunication systems

In wireless telecommunication, one of the modulation approaches used is the orthogonal frequency division multiplexing (OFDM). Moreover, the high peak‐to‐average power ratio (PAPR) is the one notorious demerit in OFDM systems. Hence, the high power amplifier (HPA) is used in its linear region. Otherwise, the bit error rate (BER) will be increased. Several approaches are proposed in the wireless communications for reducing the PAPR issue. In this paper, we propose a hybrid Discrete Hartley Matrix Transform (DHMT) precoding using both selected mapping (SLM) and partial transmit sequence (PTS) PAPR reduction strategies. For the multicarrier modulation process, instead of Inverse Fast Fourier transform (IFFT) operation, the DHMT operation is used because of its low computational complexity. Based on multi‐chaotic, the time‐frequency domain encryption (TFDE) approach is adopted for physical layer security to confirm the security in data transmission. For enhancing the physical layer security, the proposed encryption system generates chaotic sequences based on Logistic maps and Lozi in the frequency and time domains together. In this study, the implementation of the DHMT‐based OFDM system is processed to reduce the maximum PAPR. Implementation is performed on the MATLAB platform, and the performances are calculated using complementary cumulative distribution function (CCDF), BER regards to signal‐to‐noise ratio (SNR), and the outputs are compared based on the computation time. However, compared with the existing models, the proposed model produced better PAPR minimization regarding SNR.     

Digital Simulaiion of a Commercial Scale High Temperature Gas-Cooled Reactor (HTGR) Steam Power Plant

A nonlinear dynamic model of a commercial scale high temperature gas-cooled reactor (HTGR) steam power plant was derived in state-space form from fundamental principles. The plant model is 40th order, time-invariant, deterministic and continuous-time. Numerical results were obtained by digital simulation. Steady-state performance of the nonlinear model was verified with plant heat balance data at 100, 75 and 50 percent load levels. Local stability, controllability and observability were examined in this range using standard linear algorithms. Transfer function matrices for the linearized models were also obtained. Transient response characteristics of 6 system variables for independent step disturbances in 2 different input variables are presented as typical results. Simulation of the HTGR steam power plant provides the basis for (a) understanding the complex and highly interactive process dynamics, (b) designing an interactive multivariable controller, and (c) studying plant dynamic performance under various operating and upset conditions. Modeling and simulation techniques developed in the work from which this paper is abstracted have general applicability, and can be readily adapted to the study of gas-cooled steam power plants.     

Glass‐transition temperature of poly(vinylidene fluoride)‐poly(methyl acrylate) blends: Influence of aging and chain structure

The glass‐transition temperature (T_g) of the poly(vinylidene fluoride) (PVF₂)‐poly(methyl acrylate) (PMA) blends increase with aging time. The T_g versus log(time) plots are straight lines whose slope values depend on the head to head (H–H) defect content of PVF₂ samples and on the composition of the blends. The values of polymer–polymer interaction parameters (χ) increase with an increase in the H–H defect of PVF₂ for a fixed composition of the blend. Consequently, the T_g of the blend decreases with an increase in the H–H defect of the PVF₂ sample. However, after aging for longer times this decrease of the T_g with H–H defects is lower than those of the unaged blends. The possible reasons are discussed. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 1541–1548, 2001     

Initial rate study on the vapor-phase condensation of aniline to diphenylamine

The vapor-phase condensation of aniline to diphenylamine has been studied in a downflow differential reactor at 370–426°C and under atmospheric pressure using H-151 ALCOA catalyst. An initial rate equation based on the Langmuir-Hinshelwood model, i.e. surface reaction control with a similar dual site mechanism, has been proposed: r_o = (k₁K_A²p_Ao²)/ (1 + K_Ap_Ao)² The effects of different mass transfer resistances, of longitudinal and of radial dispersion have been taken into consideration. The rate constant value at 404°C is 1.488 × 10^?7 (k mol)/ (s) (kg cat) [5.358 × 10^?4 (mol)/ (h) (g cat)] and the activation energy is calculated to be 123.3 kJ/mol [29.45 k cal/mol] in the working temperature range.     

PAPR reduction using twin symbol hybrid optimization-based PTS and multi-chaotic-DFT sequence-based encryption in CP-OFDM system

Photonic Network Communications - Orthogonal frequency division multiplexing (OFDM) is considered as one of the most significant transmission methodologies of the recent past. Moreover, it permits...     

Structural and interactional homology of clinically potential typsin inhibitors: molecular modelling of Cucurbitaceae family peptides using the X-ray structure of MCTI-II

Protein Engineering, 13,     

A cluster approach to hydrogen chemisorption on the GaAs(1 0 0) surface

Chemisorption properties of atomic hydrogen on the Ga-rich GaAs(1 0 0), (2×1) and β(4×2) surfaces are investigated using ab initio self-consistent restricted open shell Hartree–Fock (ROHF) total energy calculations with Hay–Wadt (HW) effective core potentials. The effects of electron correlation have been included using many-body perturbation theory through second order with the exception of β(4×2) symmetry due to computational limitations. The semiconductor surface is modeled by finite sized hydrogen saturated clusters. The effects of surface reconstruction have been investigated in detail. We report on the energetics of chemisorption on the (1 0 0) surface layer, including adsorption beneath the surface layer at an interstitial site, and also report on the possible dimer bond breaking at the bridge site. Chemisorption energies, bond lengths, and charge population analysis are reported for all considered sites of chemisorption.     

Performance management of manufacturing system networks

Performance management of communication networks is critical for speed, reliability, and flexibility of information exchange between different components, subsystems, and sectors (e.g., factory, engineering design, and administration) of production process organizations in the environment of computer integrated manufacturing (CIM). Essential to this distributed total manufacturing system is the integrated communications network over which the information leading to process interactions and plant management and control is exchanged. Such a network must be capable of handling heterogeneous traffic resulting from intermachine communications at the factory floor, CAD drawings, design specifications, and administrative information. The objective is to improve the efficiency in handling various types of messages, e.g., control signals, sensor data, and production orders, by on-line adjustment of the parameters of the network protocol.This paper presents a conceptual design, development, and implementation of a network performance management scheme for CIM applications including flexible manufacturing. The performance management algorithm is formulated using the concepts of: (1) Perturbation analysis of discrete event dynamic systems; (2) stochastic approximation; and (3) learning automata. The proposed concept for performance management can also serve as a general framework to assist design, operation, and management of flexible manufacturing systems.The performance management procedure has been tested via emulation on a network test bed that is based on the manufacturing automation protocol (MAP) which has been widely used for CIM networking. The conceptual design presented in this paper offers a step forward to bridging the gap between management standards and users' demands for efficient network operations since most standards such as ISO and IEEE address only the architecture, services, and interfaces for network management.This work was supported in part by National Science Foundation under Research Grant No. DDM-90-15173.