A Refined Methodology for Durability-Based Service Life Estimation of Reinforced Concrete Structural Elements Considering Fuzzy and Random Uncertainties

A reliable method for service life estimation of the structural element is a prerequisite for service life design. A new methodology for durability-based service life estimation of reinforced concrete flexural elements with respect to chloride-induced corrosion of reinforcement is proposed. The methodology takes into consideration the fuzzy and random uncertainties associated with the variables involved in service life estimation by using a hybrid method combining the vertex method of fuzzy set theory with Monte Carlo simulation technique. It is also shown how to determine the bounds for characteristic value of failure probability from the resulting fuzzy set for failure probability with minimal computational effort. Using the methodology, the bounds for the characteristic value of failure probability for a reinforced concrete T-beam bridge girder has been determined. The service life of the structural element is determined by comparing the upper bound of characteristic value of failure probability with the target failure probability. The methodology will be useful for durability-based service life design and also for making decisions regarding in-service inspections.

Fuzzy logic based TCSC supplementary controller for damping of inter area oscillations in power system

This paper describes an application of a FACTS supplementary controller for damping of inter area oscillations in power systems. A fuzzy logic controller is designed to regulate a thyristor controlled series capacitor (TCSC) in a multimachine environment to produce additional damping in the system. Simultaneous application of the excitation controller and proposed controller is also investigated. Simulation studies have been done with different types of disturbances and the results are shown to be consistent with the expected performance of the supplementary controller.

Photoluminescence study of mixed doped Ge-Se-In-Bi glasses

Photoluminescence studies, carried out using the Fourier Transform method rather than the conventional monochromator-dispersion method,are reported on glassy samples of indium-bismuth mixed doped Ge (10) Se(90-x-y) In (x) Bi (y) system (x,y = 5,10). The amorphous Bi2Se3 is found to be n-type like the crystalline counterpart. The possible contributions from microscopic cluster-level phase separation of Bi2Se3 and from the defects to the change in conductivity from p- to n- typein this system is discussed. The similar situation in related systems is also pointed out.

Thermal management using the bi-disperse porous medium approach

Thermal management of distributed electronics similar to data centers is studied using a bi-disperse porous medium (BDPM) approach. The BDPM channel comprises heat generating micro-porous square blocks, separated by macro-pores. Laminar forced convection cooling fluid of Pr = 0.7 saturates both the micro- and macro-pores. Bi-dispersion effect is induced by varying the macro-pore volume fraction phi(E), and by changing the number of porous blocks N-2, both representing re-distribution of the electronics. When 0.2 <= phi(E) <= 0.86, the heat transfer No is enhanced twice (from similar to 550 to similar to 1100) while the pressure drop Delta p* reduces almost eightfold. For phi(E) < 0.5, No reduces quickly to reach a minimum at the mono -disperse porous medium (MDPM) limit (phi(E) -> 0). Compared to N-2 = 1 case, No for BDPM configuration is high when N-2 >> 1, i.e., the micro-porous blocks are many and well distributed. The Nu increase with Re changes from non-linear to linear as N-2 increases from 1 to 81, with corresponding insignificant pumping power increase. (C) 2011 Elsevier Ltd. All rights reserved.

Fuzzy Expert Approach with Curtailed Controllers for Improved Reactive Power Dispatch

This paper addresses the problem of curtailing the number of control actions using fuzzy expert approach for voltage/reactive power dispatch. It presents an approach using fuzzy set theory for reactive power control with the purpose of improving the voltage profile of a power system. To minimize the voltage deviations from pre-desired values of all the load buses, using the sensitivities with respect to reactive power control variables form the basis of the proposed Fuzzy Logic Control (FLC). Control variables considered are switchable VAR compensators, On Load Tap Changing (OLTC) transformers and generator excitations. Voltage deviations and controlling variables are translated into fuzzy set notations to formulate the relation between voltage deviations and controlling ability of controlling devices. The developed fuzzy system is tested on a few simulated practical Indian power systems and modified IEEE-30 bus system. The performance of the fuzzy system is compared with conventional optimization technique and results obtained are encouraging. Results obtained for a modified IEEE-30 bus test system and a 205-node equivalent EHV system a part of Indian southern grid are presented for illustration purposes. The proposed fuzzy-expert technique is found suitable for on-line applications in energy control centre as the solution is obtained fast with significant speedups with few number of controllers.

Inter-domain interactions influence the stability and catalytic activity of the bi-domain protein tyrosine phosphatase PTP99A

The two protein tyrosine phosphatase (PTP) domains in bi-domain PTPs share high sequence and structural similarity. However, only one of the two PIP domains is catalytically active. Here we describe biochemical studies on the two tandem PTP domains of the bi-domain PTP, PTP99A. Phosphatase activity, monitored using small molecule as well as peptide substrates, revealed that the inactive (D2) domain activates the catalytic (D1) domain. Thermodynamic measurements suggest that the inactive D2 domain stabilizes the bi-domain (D1-D2) protein. The mechanism by which the D2 domain activates and stabilizes the bi-domain protein is governed by few interactions at the inter-domain interface. In particular, mutating Lys990 at the interface attenuates inter-domain communication. This residue is located at a structurally equivalent location to the so-called allosteric site of the canonical single domain PIP, PTP1B. These observations suggest functional optimization in bi-domain PTPs whereby the inactive PTP domain modulates the catalytic activity of the bi-domain enzyme. (C) 2012 Elsevier B.V. All rights reserved.

Effect of Thickness on The Optical Properties Change in Bi/As2S3 Bilayer Thin Films

Bilayer thin films of Bi/As2S3 were prepared from Bi and As2S3 by thermal evaporation technique under high vacuum. We have prepared three bilayer films of 905nm, 910nm and 915nm thickness with with As2S3 as bottom layer (900nm) and Bi as top layer (5,10,15 nm). We have compared the optical changes due to the thickness variation of Bi layer on As2S3 film. The changes were characterized by FTIR and XPS techniques.

Raman & Infrared Study of Bi Filled Co4Sb12

CoSb3 skutterudites are established thermoelectric materials in the 500-800K temperature range. Undoped and Bi filled CoSb3 samples were synthesized by induction melting-annealing process and phase confirmation done by X-Ray diffraction. The role of bismuth as a filler in CoSb3 was investigated by Raman and far infrared reflectance study. It was found that bismuth strengthens Sb vibrations, and can potentially scatter Sb related acoustic phonons effectively. As a result substantial reduction in thermal conductivity may be possible with proper control of Bi filling.

Optical properties change with the addition and diffusion of Bi to As2S3 in the Bi/As2S3 bilayer thin film

The role of Bi layer (thickness similar to 7 nm) on As2S3 film was extensively studied for different optical applications in which Bi (top layer) as active and diffusing layer and As2S3 as barrier (matrix) layer. Bilayer thin films of Bi/As2S3 were prepared from Bi and As2S3 by thermal evaporation technique under high vacuum. The decrease of optical band gap with the addition of Bi to As2S3 has been explained on the basis of density of states and the increase in disorder in the system. It was found that the efficient changes of optical parameters (transmission, optical band gap, refraction) could be realized due to the photo induced diffusion activated by the focused 532 nm laser irradiation and formation of different bonds. The diffusion of Bi into As2S3 matrix increases the optical band gap producing photo bleaching effect. The changes were characterised by different experimental techniques. (C) 2012 Elsevier B.V. All rights reserved.

An Optimal Fuzzy Logic Controller tuned with Artificial Immune System

In this paper, a method for the tuning the membership functions of a Mamdani type Fuzzy Logic Controller (FLC) using the Clonal Selection Algorithm(CSA) a model of the Artificial Immune System(AIS) paradigm is examined. FLC's are designed for two problems, firstly the linear cart centering problem and secondly the highly nonlinear inverted pendulum problem. The FLC tuned by AIS is compared with FLC tuned by GA. In order to check the robustness of the designed PLC's white noise was added to the system, further, the masses of the cart and the length and mass of the pendulum are changed. The PLC's were also tested in the presence of faulty rules. Finally, Kruskal Wallis test was performed to compare the performance of the GA and AIS. An insight into the algorithms are also given by studying the effect of the important parameters of GA and AIS.

Thermoelectric properties of Bi-added Co4Sb12 skutterudites

Void filling in (I) Bi-x-added Co4Sb12 or (II) Sb/Bi substitution of Co4Sb12-xBix has been investigated for structural and thermoelectric properties evaluation. X-ray powder data Rietveld refinements combined with electron probe microanalyses showed a polycrystalline and practically Bi-free CoSb3 skutterudite phase as the major constituent as well as a secondary Bi phase in the grain boundaries. For series I alloys, the electrical conductivity, Seebeck coefficient and thermal conductivity were measured as a function of temperature in the range from 450 to 750 K. The electrical conductivity of all the samples increased with increasing temperature, showing a semiconducting nature with smaller values of the Seebeck coefficient for higher Bi fractions. Conduction over the entire temperature range was found to arise from a single p-type carrier. Thermal conductivity showed a reduction with Bi added in all the samples, except for Bi0.75Co4Sb12, and the lowest lattice thermal conductivity was found for a Bi-added fraction of 0.5. The maximum zT value of 0.53 at 632 K is higher than that of Co4Sb12.

Network congestion management by fuzzy inference using virtual flows

Effective network overload alleviation is very much essential in order to maintain security and integrity from the operational viewpoint of deregulated power systems. This paper aims at developing a methodology to reschedule the active power generation from the sources in order to manage the network congestion under normal/contingency conditions. An effective method has been proposed using fuzzy rule based inference system. Using virtual flows concept, which provides partial contributions/counter flows in the network elements is used as a basis in the proposed method to manage network congestions to the possible extent. The proposed method is illustrated on a sample 6 bus test system and on modified IEEE 39 bus system.

Comparison of one cycle control of charge and current for bi-directional boost rectifiers

Classical control and one cycle control of current are popular methods used to modulate pulses in active rectifiers for ac-dc power conversion. One cycle control has lower control complexity and can be implemented using linear analog circuits when compared with the classical approach. However, it also suffers from problems such as instability and offsets in current that is severe at light load conditions. A control strategy for bidirectional boost rectifiers based on one cycle control of charge is proposed for that overcomes these limitations. The integral of sensed current, which represents charge, is compared with a non-linear carrier, which is modified for ac-dc power conversion. This generates the gating signals for the switching devices. The modifications required for the control law governing one cycle control of charge is derived in the paper. Detailed simulation studies are carried out to compare one cycle control of current with the proposed method for ac-dc power conversion, which are validated on a laboratory hardware prototype.