Novel signal demodulation technique to estimate the amount of chirp in fiber Bragg gratings

A novel detection technique to estimate the amount of chirp in fiber Bragg gratings (FBGs) is proposed. This method is based on the fact that reflectivity at central wavelength of FBG reflection changes with strain/temperature gradient (linear chirp) applied to the same. Transfer matrix approach was used to vary different grating parameters (length, strength and apodization) to optimize variation of reflectivity with linear chirp. Analysis is done for different sets of `FBG length-refractive index strength' combinations for which reflectivity vary linearly with linear chirp over a decent measurement range. This article acts as a guideline to choose appropriate grating parameters in designing sensing apparatus based on change in reflectivity at central wavelength of FBG reflection.

High sensitive Static fiber Bragg grating strain sensing using lasers locked to relative frequency reference

A novel high sensitive fiber Bragg grating (FBG) strain sensing technique using lasers locked to relative frequency reference is proposed and analyzed theoretically. Static strain on FBG independent of temperature can be measured by locking frequency of diode laser to the mid reflection frequency of matched reference FBG, which responds to temperature similar to that of the sensor FBG, but is immune to strain applied to the same. Difference between light intensities reflected from the sensor and reference FBGs (proportional to the difference between respective pass band gains at the diode laser frequency) is not only proportional to the relative strain between the sensor and reference FBGs but also independent of servo residual frequency errors. Usage of relative frequency reference avoids all complexities involved in the usage of absolute frequency reference, hence, making the system simple and economical. Theoretical limit for dynamic and static strain sensitivities considering all major noise contributions are of the order of 25 (p epsilon) / root Hz and 1.2 n epsilon / root Hz respectively.

Dye sensitized visible light degradation of phenolic compounds

The present research work reports the eosin Y (EY) and fluorescein (FL) sensitized visible light degradation of phenol, 4-chlorophenol (CP), 2,4-dichlorophenol (DCP) and 2,4,6-trichlorophenol (TCP) using combustion synthesized nano-TiO2 (CS TiO2). The rate of degradation of the phenolic compounds was higher in the presence of EY/CS TiO2 compared to FL/CS TiO2 system. A detailed mechanism of sensitized degradation was proposed and a mechanistic model for the rate of degradation of the phenolic compound was derived using the pyramidal network reduction technique. It was found that at low initial dye concentrations, the rate of degradation of the phenolic compound is first order in the concentration of the dye, while at high initial dye concentrations, the rate is first order in the concentration of the phenolic compound. The order of degradation of the different phenolic compounds follows: CP > TCP > DCP > phenol. The different phenolic and dye intermediates that were formed during the degradation were identified by liquid chromatography-mass spectrometry (LC-MS) and the most probable pathway of degradation is proposed. (C) 2010 Elsevier B.V. All rights reserved.

Connectionist approach for global optimization

A connectionist approach for global optimization is proposed. The standard function set is tested. Results obtained, in the case of large scale problems, indicate excellent scalability of the proposed approach

Layered Tabu Search Algorithm for Large-MIMO Detection and a Lower Bound on ML Performance

In this paper, we are concerned with low-complexity detection in large multiple-input multiple-output (MIMO) systems with tens of transmit/receive antennas. Our new contributions in this paper are two-fold. First, we propose a low-complexity algorithm for large-MIMO detection based on a layered low-complexity local neighborhood search. Second, we obtain a lower bound on the maximum-likelihood (ML) bit error performance using the local neighborhood search. The advantages of the proposed ML lower bound are i) it is easily obtained for MIMO systems with large number of antennas because of the inherent low complexity of the search algorithm, ii) it is tight at moderate-to-high SNRs, and iii) it can be tightened at low SNRs by increasing the number of symbols in the neighborhood definition. Interestingly, the proposed detection algorithm based on the layered local search achieves bit error performances which are quite close to this lower bound for large number of antennas and higher-order QAM. For e. g., in a 32 x 32 V-BLAST MIMO system, the proposed detection algorithm performs close to within 1.7 dB of the proposed ML lower bound at 10(-3) BER for 16-QAM (128 bps/Hz), and close to within 4.5 dB of the bound for 64-QAM (192 bps/Hz).

Performance Analysis of User Selected Subband Channel Quality Indicator Feedback Scheme of LTE

Frequency-domain scheduling and rate adaptation have helped next generation orthogonal frequency division multiple access (OFDMA) based wireless cellular systems such as Long Term Evolution (LTE) achieve significantly higher spectral efficiencies. To overcome the severe uplink feedback bandwidth constraints, LTE uses several techniques to reduce the feedback required by a frequency-domain scheduler about the channel state information of all subcarriers of all users. In this paper, we analyze the throughput achieved by the User Selected Subband feedback scheme of LTE. In it, a user feeds back only the indices of the best M subbands and a single 4-bit estimate of the average rate achievable over all selected M subbands. In addition, we compare the performance with the subband-level feedback scheme of LTE, and highlight the role of the scheduler by comparing the performances of the unfair greedy scheduler and the proportional fair (PF) scheduler. Our analysis sheds several insights into the working of the feedback reduction techniques used in LTE.

Bayesian Learning for Joint Sparse OFDM Channel Estimation and Data Detection

The impulse response of a typical wireless multipath channel can be modeled as a tapped delay line filter whose non-zero components are sparse relative to the channel delay spread. In this paper, a novel method of estimating such sparse multipath fading channels for OFDM systems is explored. In particular, Sparse Bayesian Learning (SBL) techniques are applied to jointly estimate the sparse channel and its second order statistics, and a new Bayesian Cramer-Rao bound is derived for the SBL algorithm. Further, in the context of OFDM channel estimation, an enhancement to the SBL algorithm is proposed, which uses an Expectation Maximization (EM) framework to jointly estimate the sparse channel, unknown data symbols and the second order statistics of the channel. The EM-SBL algorithm is able to recover the support as well as the channel taps more efficiently, and/or using fewer pilot symbols, than the SBL algorithm. To further improve the performance of the EM-SBL, a threshold-based pruning of the estimated second order statistics that are input to the algorithm is proposed, and its mean square error and symbol error rate performance is illustrated through Monte-Carlo simulations. Thus, the algorithms proposed in this paper are capable of obtaining efficient sparse channel estimates even in the presence of a small number of pilots.

Coalition Formation With Communication Ranges and Moving Targets

A team of unmanned aerial vehicles (UAVs) with limited communication ranges and limited resources are deployed in a region to search and destroy stationary and moving targets. When a UAV detects a target, depending on the target resource requirement, it is tasked to form a coalition over the dynamic network formed by the UAVs. In this paper, we develop a mechanism to find potential coalition members over the network using principles from internet protocol and introduce an algorithm using Particle Swarm Optimization to generate a coalition that destroys the target is minimum time. Monte-Carlo simulations are carried out to study how coalition are formed and the effects of coalition process delays.

Synergistic interaction between particular X-chromosome deletions andSex-lethal causes female lethality inDrosophila melanogaster

We studied the effect on female viability of trans-heterozygous combinations of X-chromosome deficiencies and Sxt-(fl), a null allele of Sex-lethal. Twentyfive deficiencies, which together covered 80% of the X chromosome, were tested. Seven of these trans-heterozygous combinations caused significant levels of female lethality. Two of the seven interacting deficiencies include the previously known sex determination genes sans fille and sisterless-a. Four of the remaining uncover X-chromosomal regions that were not hitherto known to contain sex determination genes. These newly identified regions are defined by deficiencies Df(1)RA2 (7D10; 8A4-5), Df(1)KA14 (7F1-2; 8C6), Df(1)C52 (8E; 9C-D) and Df(1)N19 (17A1; 18A2). These four deficiencies were characterized further to determine whether it was the maternal or zygotic dosage that was primarily responsible for the observed lethality of female embryos, daughterless and extra macrochaetae, two known regulators of Sxl, influence the interaction of these deficiencies with Sxl.

Synthesis of Trilaurin by Developing Pisa Seeds (Actinodaphne hookeri)

The developing seeds of Actinodaphne hookeri were investigated to delineate their ability to synthesize large amounts of trilaurin. Until 88 days after flowering the embryos contained 71% neutral lipids (NL) and 29% phospholipids (PL) and both these components contained C-16:0, C-18:0, C-18:2, and C-18:3 as the major fatty acids (FA). At 102 days after flowering the seeds began to accumulate triacylglycerols (TAG) and to synthesize lauric acid (C-12:0). By 165 days after flowering, when the seeds were mature, they contained about 99% NL and 1% FL. At this stage the TAG contained exclusively C-12:0, while the PL consisted of long-chain fatty acids (LCFA) only. Leaf lipids in contrast did not contain any C-12:0. Experiments on [1-C-14]acetate incorporation into developing seed slices showed that at 88 days after flowering only 4% of the label was in TAG, 1% in diacylglycerols (DAG), and 87% in FL. One hundred two days after flowering seeds incorporated only 2% of the label into TAG, 30% into DAG, and 64% into FL. In contrast at 114 days after flowering 71% of the label was incorporated into TAG, 25% into DAG, and only 2% into FL. Analysis of labeled FA revealed that up to 102 days after flowering it was incorporated only into LCFA, whereas at 114 days after flowering it was incorporated exclusively into C-12:0. Furthermore, 67% of the label in PL at 114 days after flowering was found to be dilaurylglycerophosphate. Analysis of the label in DAG at this stage showed that it was essentially in dilaurin species. These observations indicate the induction of enzymes of Kennedy pathway for the specific synthesis of trilaurin at about 114 days after flowering, Homogenates of seeds (114 days after flowering) incubated with labeled FA in the presence of glycerol-3-phosphate and coenzymes A and ATP incorporated 84% of C-12:0 and 61% of C-14:0, but not C-16:0, C-18:2, and C-18:3, into TAG. In contrast the LCFA were incorporated preferentially into FL. It is concluded that, between 102 and 114 days after flowering, a switch occurs in A. hookeri for the synthesis of C-12:0 and trilaurin which is tissue specific. Since the seed synthesizes exclusively C-12:0 at 114 days after flowering onwards and incorporates specifically into TAG, this system appears to be ideal for identifying the enzymes responsible for medium-chain fatty acid as well as trilaurin synthesis and for exploiting them for genetic engineering. (C) 1994 Academic Press, Inc.

ATP hydrolysis is required for DNA cleavage by EcoPI restriction enzyme

The type III restriction endonuclease EcoPI, coded by bacteriophage Fl, cleaves unmodified DNA in the presence of ATP and magnesium ions. We show that purified EcoPI restriction enzyme fails to cleave DNA in the presence of non-hydrolyzable ATP analogs. More importantly, this study demonstrates that EcoPI restriction enzyme has an inherent ATPase activity, and ATP hydrolysis is necessary for DNA cleavage. Furthermore, we show that the progress curve of the reaction with Eco PI restriction enzyme exhibits a lag which is dependent on the enzyme concentration. Kinetic analysis of the progress curves of the reaction suggest slow transitions that can occur during the reaction, characteristic of hysteretic enzymes. The role of ATP in the cleavage mechanism of type III restriction enzymes is discussed.

Combustion studies on concentrated distillery effluents

Studies on ignition and combustion of distillery effluent containing solids consisting of 38 +/- 2% inorganics and 62 +/- 2% of organics (cane sugar derivatives) have been carried out in order to investigate the role of droplet size and ambient temperature in the process of combustion. Experiments were conducted on in liquid droplets of effluent having solids concentration 65% and (2) spheres of died (100% solids) effluent of diameters ranging from 0.5 to 25 mm. These spheres were introduced into a furnace where air temperature ranged from 500 to 1000 degrees C, and they burned with two distinct regimes of combustion-flaming and glowing. The ignition delay of the 65% concentration effluent increases with diameter as in the case of nonvolatile droplets, while that of dried spheres appears to be independent of size. The ignition delay shows Arrhenius dependence on temperature. The flaming combustion involves a weight loss of 50-80%, depending on ambient temperature, and the flaming time is given by t(f) similar to d(0)(2), as in the case of liquid fuel droplets and wood spheres. Char glowing involves weight loss of an additional 10-20%, with glowing time behaving as t(c) similar to d(0)(2) as in the case of wood char, even though the inert content of effluent char is as large as 50% compared to 2-3% in wood char Char combustion has been modeled, and the results of this model compare well with the experimental results.

Development of specific DNA probes and their usage in the detection of Plasmodium vivax infection in blood

The application of nucleic acid probes, in the detection of pathogenic micro-organisms, has become an integral part of diagnostic technologies. In this study, Plasmodium vivax-specific DNA probes have been identified by carrying out genomic subtractive hybridization. In this approach, the recombinant clones from a P. vivax genomic library are screened with radiolabelled human and P. falciparum DNA. The colonies which react with labelled P. falciparum and human DNA are eliminated and those which do not produce any autoradiographic signal have been subjected to further screening procedures. Three Fl vivax specific DNA probes have been obtained by these repeated screenings. Further analyses indicate that these probes are specific and sensitive enough to detect P. vivax infection in clinical blood samples when used in a non-radioactive DNA hybridization assay. (C) 1995 Academic Press Limited

Structure of Ethyl 5-Methoxy-3-phenyl-2-indolecarboxylate

C18H17NO3, M r = 295"34, monoclinic, C2/c, a = 11.689 (2), b = 22.934 (4), c = 11.592 (2) A, fl=100.16(3) ° , V =3058.8(8) A 3, Z=8, D,n= 1.30 (5), Dx = 1.28 Mg m -3, A(Mo Ka) = 0.7107 A, tz(Mo Ka) = 0.094 mm- 1, F(000) = 1248, T = 300 K, final R = 0.046 for 1849 observed reflections [I > 30"(/)]. The indole nucleus is slightly bent along the C(8)---C(9) bond. The phenyl ring connected to the indole moiety is rotated about the C(3)---C(10) bond by 45.8 (3) °. The carboxyl group makes a dihedral angle of 8.1 (4) ° with the mean plane of the indole moiety. Centrosymmetrically related pairs of molecules are linked through hydrogen bonds across the centre of symmetry and form dimers.