Application of battery energy storage system to load frequency control of an isolated power system

A battery energy storage system (BES) can provide fast active power compensation and hence it also can be used to improve the performance of the load frequency control. In this paper, the study is carried out on a single area model representing the whole power system considering generation rate constraint (GRC). An incremental model of BES is proposed and merged into the load frequency control of the power system. Optimum value of integral gain setting is obtained using integral squared technique (ISE). Dynamic responses of the system are presented with and without considering BES facility. Analysis reveals that BES improves the system performance significantly. Copyright © 1999 John Wiley & Sons, Ltd.     

Shielded edge-coupled coplanar waveguide structures: Modes and field configurations

In this article we present the dispersion characteristics as well as frequency-dependent field configuration and characteristic impedance for edge-coupled, shielded, coplanar waveguide structures. The structures studied include conductor-backed and suspended configurations. Phenomena such as mode conversion and dispersion of the dominant modes are explained. The characteristic impedance behavior is shown to be directly related to the phenomenon of mode conversion. The analysis uses the method of lines. © 1996 John Wiley & Sons, Inc.     

Interconnected operation of small-hydroelectric and diesel power systems

The paper deals with some aspects of the interconnected operation of small-hydroelectric and diesel power systems provided with classical controllers. A comprehensive procedure for optimizing the integral controller gain setting using an integral squared error (ISE) technique is suggested. Analysis reveals that the integral-derivative (ID) controller in the small-hydroelectric area and integral controller in the diesel area improves the system performance significantly as compared to that of integral control in both areas. Analysis also reveals that the continuous frequency and tie-power oscillations can completely be eliminated using an ID controller in the small-hydroelectric area. © 1998 John Wiley & Sons, Ltd.     

Grain size engineered Ba0.9Sr0.1Ti0.9Hf0.1O3-Na0.5Bi0.5TiO3 relaxor ceramics with improved energy storage performance

Novel lead-free diphasic (1-x)Ba_0.9Sr_0.1Ti_0.9Hf_0.1O₃-xNa_0.5Bi_0.5TiO₃ (BSTH-NBT) ceramic nanocomposites were synthesized via an economically viable modified mechano-chemical activation technique. In the present investigation, we have developed an energy storage composite material by systematically optimizing the charge transport behavior and charge storage characteristics between the ferroelectric BSTH and piezoelectric NBT phase. The composite with x = 0.09 NBT concentration has shown the best energy storage properties with 1.61 J/cm³ discharge energy density along with 80.1% energy efficiency. The BSTH and NBT had a synergetic effect on the ferroelectric properties of the composites. The improvement in ferroelectric and piezoelectric properties along with excellent aging characteristics in composite materials is mainly attributed to enhancement in microstructural density, grain boundary interface, and stress effects. The improved dispersibility and excellent compatibility between BSTH and NBT phase have resulted in approximately 20% enhancement in breakdown strength of composite compared to pure BSTH ceramic.     

A continuum‐approach modeling of surface composition and ternary component distribution inside low fat milk emulsions during single droplet drying

Surface composition of dairy powders plays an important role in determining the functionality. However, the surface composition may be different from the bulk composition because of component migration during drying. In this study, a comprehensive mathematical model has been developed to describe the phenomena. To the best of our knowledge, it is the first mathematical model which predicts the dynamics of surface composition during drying. The model consists of a set of equations of conservation of mass of water, lactose, protein, and fat as well as conservation of heat and momentum in which the effects of diffusion induced material migration and surface activity are incorporated. This model is applicable to describe the kinetics of surface composition of dairy droplets during drying. It suggests that both diffusion and protein surface activity govern the component segregation during drying. The study indicates that the model implementing the measured initial surface composition as the initial conditions generates more realistic profiles than the one using the bulk composition. The modeling confirms that the difference between the surface and bulk composition that occurs prior to drying is not primarily governed by diffusion, but the emulsion's atomization behavior seems to play an essential role in the overrepresentation of fat. © 2017 American Institute of Chemical Engineers AIChE J, 63: 2535–2545, 2017     

Interference-aware feedback based iterative Hungarian approach to allocate multiple channels to multiple D2D pairs to maximize underlay D2D network capacity

The spectral efficiency of a cellular network can be increased significantly by allowing spatial reuse of its spectrum by an underlay device-to-device (D2D) network. In an underlay D2D network, devices in close vicinity are allowed to establish low-power direct links with little to no involvement of the base station. In order to increase the spectral efficiency and the number of devices with channel access, multiple D2D pairs may transmit in each cellular channel. Additionally, each pair can be allowed to utilize multiple channels to transmit so as to maximize the D2D network capacity. This multiple-pair multiple-channel (MPMC) strategy is quite appealing but is limited by the resultant additional aggregate interference and the inherent complexity, hence necessitating the need for a fast and reliable channel allocation scheme. This work proposes a polynomial-time iterative Hungarian assignment with feedback (IHAF) algorithm for multiple channel allocations amongst multiple D2D pairs that increases the D2D network capacity manifold while maintaining the desired minimum capacity for each cellular user.     

Superconducting state parameters of Pb-Tl-Bi alloys

An extensive theoretical study of the superconducting state parameters (SSPs), that is, electron-phonon coupling strength λ, Coulomb pseudopotential μ*, transition temperature T _C , isotope effect exponent α, and effective interaction strength N ₀ V of Pb-Tl-Bi alloys, including Tl_0.90Bi_0.10, Pb_0.40Tl_0.60, Pb_0.60Tl_0.40, Pb_0.80Tl_0.20, Pb_0.60Tl_0.20Bi_0.20, Pb_0.90Bi_0.10, Pb_0.80Bi_0.20, Pb_0.70Bi_0.30, Pb_0.65Bi_0.35, and Pb_0.45Bi_0.55, has been conducted for the first time using model potential formalism. A considerable influence of various exchange and correlation functions on λ and μ* is found. The obtained values of the SSPs are in qualitative agreement with the available experimental data.     

Variable Step Size Affine Projection Algorithm for Adaptive Multiuser DS-CDMA MMSE Receiver

In this paper, we consider the use of affine projection algorithm (APA) for interference suppression in direct sequence code-division multiple-access (DS-CDMA) system. We first derive the multiuser fixed step-size APA (FSS-APA) algorithm. The computational complexity offered by the APA algorithm is linear in terms of the number of taps with additional terms of O (L ²) and a matrix inversion of dimension L, where L is known as the order of the filter. The value of L is chosen very small as compared to the number of filter-taps N _T . We next propose a novel variable step-size APA (VSS-APA) algorithm, which further improves the performance of the FSS-APA algorithm with very small increase in computational complexity as compared to the FSS-APA. It is demonstrated that the performance of the APA based minimum mean-square error (MMSE) receivers is far superior to that of the normalized least-mean-square (NLMS) based receivers. Though, the recursive-least-square (RLS) algorithm based adaptive receivers offer better performance but at the cost of much higher computational complexity.     

Study of Screening Dependence Superconducting State Parameters of Cu<Subscript><Emphasis Type="Italic">C</Emphasis></Subscript>Zr<Subscript>100−<Emphasis Type="Italic">C</Emphasis></Subscript> Binary Metallic Glasses by a Pseudopotential

The screening dependence theoretical investigations of the superconducting state parameters (SSP) viz. electron–phonon coupling strength λ, Coulomb pseudopotential μ ^*, transition temperature T _C , isotope effect exponent α and effective interaction strength N _O V of ten binary Cu _C Zr_100−C (C=25, 30, 33, 35, 40, 45, 50, 55, 57 and 60) metallic glasses have been reported using Ashcroft’s empty core (EMC) model potential. Five local field correction functions proposed by Hartree (H), Taylor (T), Ichimaru–Utsumi (IU), Farid et al. (F), and Sarkar et al. (S) are used in the present investigation to study the screening influence on the aforesaid properties. It is observed that the electron–phonon coupling strength λ and the transition temperature T _C are quite sensitive to the selection of the local field correction functions, whereas the Coulomb pseudopotential μ ^*, isotope effect exponent α and effective interaction strength N _O V show weak dependences on the local field correction functions. The values of T _C obtained from the H-local field correction function are in qualitative agreement with available theoretical or experimental data and show almost linear nature with the concentration C of Cu element. A linear T _C equation is proposed by fitting the present outcomes for the H-local field correction function, which is in conformity with other results for the experimental data. Also, the present results are in qualitative agreement with other such earlier reported data, which confirms the superconducting phase in the metallic glasses.