Cross Interference Research Articles

Tracing methane dissolved in transformer oil by tunable diode laser absorption spectrum

Dissolved gas analysis (DGA)in power transformers is related to the degradation of insulation materials and dissolved methane (CH 4 )is a symbol gas of low energy electrical or thermal faults in power transformer oil. Conventional online DGA equipment suffers from problems such as cross sensitivity, electromagnetic compatibility and reliability. Based on tunable diode laser absorption spectroscopy (TDLAS) technique, a novel optical method is proposed to detect dissolved methane in transformer oil. Oil samples with fault gases are prepared and dissolved methane detection has been carried out in the laboratory. 1653.72 nm is selected as the central wavelength of tunable diode laser, moreover, a multipass gas cell and wavelength modulation strategy is utilized to trace methane dissolved in oil. Results show that the resolution of detection reaches 0.28 µL/L, and accuracy is less than 2 µL/L at low concentration. In addition, the detection cycle is so time-saving, less than 5 minutes. The proposed measurement method shows tremendous advantages, such as immediate response to concentration changes, no cross interference, no carrier gases, which is proved to be a promising maintain-free technique instead of conventional DGA equipment.

A Collaboration Incentive Exploiting the Primary-Secondary Systems’ Cross Interference for PHY Security Enhancement

We investigate the spectrum sharing possibility as an incentive to enhance the physical layer security. The concept behind is that a legitimate source-destination pair, communicating in the presence of a passive eavesdropper, stimulates the help of another source-destination nodes looking for transmission opportunities, referred to as secondary network (SN). We thus propose a cooperative scheme, whereby the secondary transmitter (ST) will act as a friendly jammer to confound the eavesdropper and be granted to share the spectrum of the legitimate pair, referred to as primary network (PN), as a reward. Meanwhile, the ST has to secure its own secrecy communication and thus exploit the impact of the induced interference by the PN. To evaluate the performance of our cooperative scheme, we derive the closed-form expressions of the secrecy outage probability (SOP) for both cooperative networks. However, to assess its usefulness, we introduce the mutual outage probability (MOP) and we carry out analysis to derive its expression. We show that a satisfactory SOP is a necessary condition for triggering the cooperation, whereas a satisfactory MOP is a sufficient condition to guarantee that the PN–SN collaboration leads to a win–win situation. Furthermore, an asymptotic analysis is also carried out to derive the generalized secrecy diversity for the scheme under investigation, where it has been shown that the primary system achieves its full secrecy diversity order, equal to the number of antenna at the primary transmitter. Such results present useful insights for practical design and setups.

Tunable Negative Group Delay in a Birefringent Fabry–Pérot-Like Cavity With High Fractional Advancement Induced by Cross-Interference Effect

A strong and broadband negative group delay (NGD) is demonstrated in a circular waveguide with an asymmetric cross-shaped slotted structure in the millimeter-wave region. For an input of 45° linear polarization (relative to the orientation of the cross-shaped slots), the NGD fractional bandwidth is as high as 3.57%, in which the optimal group advancement obtained is nearly 24 times greater than the delay traveling with the speed of light in vacuum. This further indicates a very high fractional advancement of 12.10%. In addition, the NGD can be controlled by adjusting the polarization azimuthal angle of the incident pulse. The observed tunable NGD effect is attributed to the destructive cross interference between the two polarization eigenstates, which effectively reduces the released field energy at the observed polarization channel. A general theory is provided with excellent agreement in the experimental and simulation results.

Adaptive estimation of state of charge and capacity with online identified battery model for vanadium redox flow battery

Abstract Reliable state estimate depends largely on an accurate battery model. However, the parameters of battery model are time varying with operating condition variation and battery aging. The existing co-estimation methods address the model uncertainty by integrating the online model identification with state estimate and have shown improved accuracy. However, the cross interference may arise from the integrated framework to compromise numerical stability and accuracy. Thus this paper proposes the decoupling of model identification and state estimate to eliminate the possibility of cross interference. The model parameters are online adapted with the recursive least squares (RLS) method, based on which a novel joint estimator based on extended Kalman Filter (EKF) is formulated to estimate the state of charge (SOC) and capacity concurrently. The proposed joint estimator effectively compresses the filter order which leads to substantial improvement in the computational efficiency and numerical stability. Lab scale experiment on vanadium redox flow battery shows that the proposed method is highly authentic with good robustness to varying operating conditions and battery aging. The proposed method is further compared with some existing methods and shown to be superior in terms of accuracy, convergence speed, and computational cost.

Polarized digital shearography for simultaneous dual shearing directions measurements.

The selection of the direction of sensitivity for digital shearography is determined by its shearing direction. As a result, directionally shaped defects could be missed in non-destructive testing using a digital shearography system with only one shearing direction. This paper reports a polarized digital shearography system based on two Mach-Zehnder interferometers, which can create two orthogonal shearing directions and record shearograms in the two orthogonal directions simultaneously. The two shearograms are separated from each other by proper polarization design so that no cross interference occurs. The phase maps of the shearograms are generated by spatial phase shift methods through the introduction of different carrier frequencies in the two orthogonal shearograms and use of the Fourier transform method. This enabled simultaneous dual directional non-destructive testing during continuous loading. Theory derivation, spectrum analysis, and non-destructive testing application results are shown in detail.

Cantilever enhanced photoacoustic spectrometry: Quantitative analysis of the trace H2S produced by SF6 decomposition

As one of the key characteristic components that result from sulfur hexafluoride (SF6) decomposition in SF6 gas-insulated equipment, hydrogen sulfide (H2S) can reflect the severity of the internal insulation faults and indicate whether or not such faults involve solid insulation material effectively. The decomposition of SF6 and its reaction with other impurities to form H2S are simulated in this study via Materials Studio. The simulation verifies that H2S is generated only when serious faults occur in the equipment; thus, the online monitoring of the trace H2S is highly necessary. To achieve a high detection accuracy and avoid cross interference, the spectral line R (8) of the H2S ν1+ν2+ν3 co-frequency absorption band is taken as the absorption line for the gas detection by online simulation based on the HITRAN on the Web. In addition, this study develops a cantilever-enhanced photoacoustic spectrometry trace gas detection platform and conducts experimental research on the quantitative detection of trace H2S/SF6 and H2S/N2. Experimental results show that the detection sensitivity of the detection platform to trace H2S under the background gas N2 and SF6 is 0.84 and 1.75μL/L, respectively, and a strong linear relationship exists between the trace H2S concentration and its corresponding PA signal. Moreover, based on both the theoretical simulation and experiment, the influence of temperature and pressure on the detection platform is discussed and analyzed. The results indicate that the change in the PA signal amplitude decreases with an increase in the pressure or temperature of the PA cell, and the detection platform is more sensitive to pressure.

A synthetic research on the multimedia data encryption based mobile computing security enhancement model and multi-channel mobile human computer interaction framework

With the development of computer network, people could obtain information through the network with stronger impulsion, the dependence of the requirements also becomes higher, this is not only reflected in the increase of information, but to obtain and submit more reflected in real-time and easy to access to information on the pressing needs of the. Therefore, people devoted all aspects from the terminal, network and software platforms to make unremitting efforts. Under this basis, we conduct synthetic research on the data encryption based mobile computing security enhancement model and multi-channel mobile human computer interaction framework in this paper. We firstly introduce the discrete-time Hopfield neural network based data encryption algorithm beyond the analysis on the information flow security and type based model, data security review and attack model under mobile computing environment. We improve learning algorithm of the MD method to avoid the sample mobile and cross interference problems of Hebb rule. Later, we integrate the multi-channel concept to propose the new multi-channel man–machine interaction. In our framework, the 3D interactive technology, speech recognition and synthesis technology, natural language understanding and processing technology, eye tracking technology, posture, input, tactile, force display basic technology are taken into consideration for the synthetic analysis. The result from the experimental simulation proves that our methodology obtains better effectiveness and feasibility from both the angels of data security and interface experience.

Energy Optimization for Bidirectional Multimedia Communication in Unsynchronized TDD Systems

Energy efficiency is one of the main system resources that has to be optimally allocated, due to its impact on the amount of generated interference and the battery life for multimedia communication. In this paper, we concentrate on the time-division duplexing (TDD) option and how to efficiently allocate energy on both uplink (UL) and downlink (DL) channels that share the same bandwidth but over different time intervals. One of the main advantages of TDD is the possibility for load compensation between UL and DL, by allocating a larger percentage of time for the operation in DL if the system is congested in DL, and vice versa. While this allocation can be done on each cell independently, the result is that adjacent cells would have a different compensation value, thus generating cross interference, which decreases the system performance, mainly on the cell-edge users. This paper presents an energy allocation in order to compensate the unsynchronization in the percentage allocation, where the objective is to guarantee minimum quality of service satisfaction at all receivers, while the least amount of energy is consumed.

Online state of charge and model parameter co-estimation based on a novel multi-timescale estimator for vanadium redox flow battery

A key function of battery management system (BMS) is to provide accurate information of the state of charge (SOC) in real time, and this depends directly on the precise model parameterization. In this paper, a novel multi-timescale estimator is proposed to estimate the model parameters and SOC for vanadium redox flow battery (VRB) in real time. The model parameters and OCV are decoupled and estimated independently, effectively avoiding the possibility of cross interference between them. The analysis of model sensitivity, stability, and precision suggests the necessity of adopting different timescales for each estimator independently. Experiments are conducted to assess the performance of the proposed method. Results reveal that the model parameters are online adapted accurately thus the periodical calibration on them can be avoided. The online estimated terminal voltage and SOC are both benchmarked with the reference values. The proposed multi-timescale estimator has the merits of fast convergence, high precision, and good robustness against the initialization uncertainty, aging states, flow rates, and also battery chemistries.

Auxiliary Circuits for Power Flow Control in Multifrequency Wireless Power Transfer Systems With Multiple Receivers

This paper describes a technique for multifrequency wireless power transfer systems in which the wireless power can be transmitted through the wireless power transfer channel or channels from the transmitter to the targeted loads with receiver coils specifically tuned for energy reception. Auxiliary circuits comprising bandpass and/or bandstop circuits are proposed for incorporation into the receiver circuits and optional relay circuits so as to facilitate the selection and enhancement of the wireless power transfer to the designated load without causing significant cross interference due to the use of multifrequency wireless power flow control. A unique feature of this technique is that the nontargeted receiver will automatically act as a relay resonator to enhance 1) magnetic coupling, and thus, 2) the power transfer between the power transmitter and the targeted receiver. A second novel feature is that the chosen operating frequencies for the tuned receivers need not be widely apart because the auxiliary circuits consist of bandpass and/or bandstop filters to reduce any cross interference from the nontargeted frequency. The proposed technique has been practically verified in experimental prototype.

Preparation and Characterization of a Triple Layered Au‐PMMA‐PbSe Hybrid Nanocomposite: Manipulation of PMMA Spacer Layer by Oxygen Plasma Etching

A hybrid triple‐layered nanocomposite structure of plasmonic gold (Au), polymethylmethacrylate (PMMA), and lead selenide (PbSe) quantum dot (QD) on quartz substrate was developed. The fabricated nanocomposite exhibited well‐established triple‐layered morphology (Au‐PMMA‐QD on quartz), but had different coupling distances between Au, on the bottom, and PbSe QD, on the top. Control of the coupling distances in terms of different thicknesses of a PMMA spacer layer was examined by etching for different durations, from 7 to 30 min. The corresponding thicknesses of the PMMA layer ranged from ~3.8 to ~88 nm at an etching rate of 2 nm/min. Atomic force microscopy measurements showed that the well‐established triple‐layered hybrid nanocomposite structure had the heights of ~15 nm (Au) and ~4 nm (PbSe QD). X‐ray photoelectron spectroscopy results revealed the characteristic peaks assigned to each nanoparticle and polymer layer. The results illustrated the triple‐layered structures with different PMMA spacer layers, with no cross interference between the layers.

Guided Wave Propagation in a Gold Electrode Film on a Pb(Mg1/3Nb2/3)O3−33%PbTiO3 Ferroelectric Single Crystal Substrate

Dispersion relations of Love mode acoustic guided waves propagation in Pb(Mg1/3Nb2/3)O3−33%PbTiO3 (PMN-0.33 PT) single crystal with a gold electrode film are calculated. There is no cross coupling among Love wave modes, which is conducive to eliminating the cross interference between modes. The general formula is derived to precisely measure the thickness of the electrode. More acoustic energy would be concentrated inside the electrode with the increase of film thickness for a given frequency. Compared with the PZT-5 ceramic, [001]c poled PMN-33%PT single crystal has a slower attenuation of the amplitude of the acoustic guided wave. Therefore, single crystal is extremely suitable for making low loss acoustic wave devices with a high operating frequency.

Role of antioxidants in electro catalytic activity of cytochrome P450 3A4

The electrochemical analysis of cytochrome Р450 3А4 catalytic activity has shown that vitamins C, A and Е influence on electron transfer and Fe3+/Fe2+ reduction process of cytochrome Р450 3А4. These data allow to assume possibility of cross effects and interference of vitamins-antioxidants with drugs metabolised by cytochrome Р450 3А4, at carrying out of complex therapy. This class of vitamins shows antioxidant properties that lead to increase of the cathodic current corresponding to heme reduction of this functionally significant haemoprotein. Ascorbic acid of 0.028-0.56 mM concentration stimulates cathodic peak (an electrochemical signal) of cytochrome Р450 3А4. At the presence of diclofenac (Voltaren) - a typical substrate of cytochrome Р450 3А4 - the increase growth of a catalytic current testifying to an electrocatalysis and stimulating action of ascorbic acid is observed. In the presence of vitamins A and Е also is registered dose-dependent (in a range of 10-100 M) increase in a catalytic current of cytochrome Р450 3А4: the maximum increase corresponds to 229 ± 20% for 100 M of vitamin A, and 162±10% for 100 M of vitamin E. Vitamin E in the presence of P450's inhibitor itraconazole doesn't give essential increase in a reductive current, unlike retinol (vitamin A). This effect can manifest substrate properties of tocopherol (vitamin E). The electrochemical approach for the analysis of catalytic activity of cytochrome Р450 3А4 and studies of influence of biologically active compounds on an electrocatalysis is the sensitive and effective sensor approach, allowing to use low concentration of protein on an electrode (till 10-15 mol/electrode), to carry out the analysis without participation of protein redox partners, and to reveal drug-drug or drug-vitamins interaction in pre-clinical experiments.

Application of distributed sensor networks for estimating exposures to air pollution in urban areas

Background: Urban air quality is a major concern given the health effects associated with traffic related air pollutants. To date, exposure estimates used in environmental epidemiology studies are unable to resolve the fine spatial structure of air pollution at urban areas, where emission sources and sinks are extremely variable both in space and in time and create microenvironments of great diversity. New technologies recently emerged based on mini sensors for air pollutants. Aims: Test the applicability of mini air pollution sensors for an urban environment as distributed sensors network (DSN). Methods: 1.Sensors for several pollutants (NO2, O3, CO) as well as temperature and relative humidity were compared to standard air quality monitors (AQM) at Haifa, Israel. 2. At an “across the street” experiment, sensors were placed on opposite sides of a busy road. 3. Sub-neighborhood scale variations were examined by mounting the sensors on private vehicles. Results: Sensors collocated at a roadside and an urban background AQM sites showed good agreement with standard measurements, though with significant bias during periods with high RH. Excellent correlations between traffic related primary pollutants were observed, which deteriorated as the distance to traffic increased. When placed across the street, higher NO2 and CO (5 ppb and 0.4 ppm, respectively) and lower O3 (13 ppb) concentrations were measured by the downwind vs. the upwind sensors. At the sub-neighborhood scale, the sensors were able to detect the fine spatial pollution structure near busy vs. quiet streets. A clear spatial negative correlation between NO2 and O3 concentrations was obtained. Conclusions: DSN have a potential to complement standard urban AQM networks, and may provide improved exposure estimates at the individual and the population level. Further research is needed for improving the current technology, analysis and interpretation of the measurements, and for accounting for the effect of ambient conditions as well as cross interference with other pollutants.

Stack emission monitoring using non-dispersive infrared spectroscopy with an optimized nonlinear absorption cross interference correction algorithm

Abstract. In this paper, we present an optimized analysis algorithm for non-dispersive infrared (NDIR) to in situ monitor stack emissions. The proposed algorithm simultaneously compensates for nonlinear absorption and cross interference among different gases. We present a mathematical derivation for the measurement error caused by variations in interference coefficients when nonlinear absorption occurs. The proposed algorithm is derived from a classical one and uses interference functions to quantify cross interference. The interference functions vary proportionally with the nonlinear absorption. Thus, interference coefficients among different gases can be modeled by the interference functions whether gases are characterized by linear or nonlinear absorption. In this study, the simultaneous analysis of two components (CO2 and CO) serves as an example for the validation of the proposed algorithm. The interference functions in this case can be obtained by least-squares fitting with third-order polynomials. Experiments show that the results of cross interference correction are improved significantly by utilizing the fitted interference functions when nonlinear absorptions occur. The dynamic measurement ranges of CO2 and CO are improved by about a factor of 1.8 and 3.5, respectively. A commercial analyzer with high accuracy was used to validate the CO and CO2 measurements derived from the NDIR analyzer prototype in which the new algorithm was embedded. The comparison of the two analyzers show that the prototype works well both within the linear and nonlinear ranges.

Intercomparison of NO<sub>3</sub> radical detection instruments in the atmosphere simulation chamber SAPHIR

Abstract. The detection of atmospheric NO3 radicals is still challenging owing to its low mixing ratios (≈ 1 to 300 pptv) in the troposphere. While long-path differential optical absorption spectroscopy (DOAS) has been a well-established NO3 detection approach for over 25 yr, newly sensitive techniques have been developed in the past decade. This publication outlines the results of the first comprehensive intercomparison of seven instruments developed for the spectroscopic detection of tropospheric NO3. Four instruments were based on cavity ring-down spectroscopy (CRDS), two utilised open-path cavity-enhanced absorption spectroscopy (CEAS), and one applied "classical" long-path DOAS. The intercomparison campaign "NO3Comp" was held at the atmosphere simulation chamber SAPHIR in Jülich (Germany) in June 2007. Twelve experiments were performed in the well-mixed chamber for variable concentrations of NO3, N2O5, NO2, hydrocarbons, and water vapour, in the absence and in the presence of inorganic or organic aerosol. The overall precision of the cavity instruments varied between 0.5 and 5 pptv for integration times of 1 s to 5 min; that of the DOAS instrument was 9 pptv for an acquisition time of 1 min. The NO3 data of all instruments correlated excellently with the NOAA-CRDS instrument, which was selected as the common reference because of its superb sensitivity, high time resolution, and most comprehensive data coverage. The median of the coefficient of determination (r2) over all experiments of the campaign (60 correlations) is r2 = 0.981 (quartile 1 (Q1): 0.949; quartile 3 (Q3): 0.994; min/max: 0.540/0.999). The linear regression analysis of the campaign data set yielded very small intercepts (median: 1.1 pptv; Q1/Q3: −1.1/2.6 pptv; min/max: −14.1/28.0 pptv), and the slopes of the regression lines were close to unity (median: 1.01; Q1/Q3: 0.92/1.10; min/max: 0.72/1.36). The deviation of individual regression slopes from unity was always within the combined accuracies of each instrument pair. The very good correspondence between the NO3 measurements by all instruments for aerosol-free experiments indicates that the losses of NO3 in the inlet of the instruments were determined reliably by the participants for the corresponding conditions. In the presence of inorganic or organic aerosol, however, differences in the measured NO3 mixing ratios were detectable among the instruments. In individual experiments the discrepancies increased with time, pointing to additional NO3 radical losses by aerosol deposited onto the filters or on the inlet walls of the instruments. Instruments using DOAS analyses showed no significant effect of aerosol on the detection of NO3. No hint of a cross interference of NO2 was found. The effect of non-Lambert–Beer behaviour of water vapour absorption lines on the accuracy of the NO3 detection by broadband techniques was small and well controlled. The NO3Comp campaign demonstrated the high quality, reliability and robustness of performance of current state-of-the-art instrumentation for NO3 detection.

Spectrum Sharing with Limited Channel Feedback

In this paper, an underlay spectrum sharing scheme is proposed where both primary and secondary users are discrete power-rate adaptive systems with limited feedback from receivers. By receiving secondary and overhearing primary quantized channel quality information from the secondary receiver and primary receiver, respectively, the secondary transmitter adapts its resource allocation to the current channel quality by selecting a proper power-rate pair from a pre-designed secondary quantization codebook. The secondary quantization codebook is designed to maximize the secondary average rate subject to the primary rate loss constraint and the average secondary transmit power constraint, which is discussed in three cases when different amount of side information of the primary codebook and the cross interference link are available at the secondary receiver side. Differential Evolution algorithm is employed to provide the global optimal solutions to the proposed secondary quantization codebook optimization problems. Numerical results show that, by introducing the secondary feedback, the secondary throughput is greatly improved. Furthermore, more secondary feedback bits or more primary side information result in better secondary performance.

The effect of antioxidants on electrocatalytic activity of cytochrome P450 3A4

The electrochemical analysis of cytochrome P450 3A4 catalytic activity has shown that vitamins C, A and E influence reduction of cytochrome P450 3A4. These data suggest a possibility of cross effects and interference of vitamins-antioxidants with drugs metabolised by cytochrome P450 3A4, during complex therapy of patients. These vitamins demonstrate antioxidant properties that lead to the increase of the cathodic current corresponding to heme reduction of this functionally significant hemoprotein. Ascorbic acid (0.028–0.56 mM) stimulated the cathodic peak (an electrochemical signal) of cytochrome P450 3A4. In the presence of diclofenac (Voltaren), a typical substrate of cytochrome P450 3A4, the increase in the catalytic current suggesting electrocatalysis and stimulating action of ascorbic acid was observed. In the presence of vitamins A and E the dose-dependent increase in the catalytic current of cytochrome P450 3A4 was observed in the range of vitamin concentrations from 10 to 100 μM. The maximal increase of 229 ± 20 and 162 ± 10% was observed at 100 μM vitamin A and vitamin E, respectively. In contrast to vitamin A, vitamin E in the presence of the cytochrome P450 inhibitor itraconazole did not increase the catalytic current. The latter implies existence of some substrate properties in vitamin E. The electrochemical approach for the analysis of catalytic activity of cytochrome P450 3A4 and studies of the effect of biologically active compounds on electrocatalysis is the sensitive and effective sensor approach, allowing to use low concentration of protein on an electrode (up to 10–15 mol/electrode), to carry out the analysis without involvement of protein redox partners, and to reveal drug-drug or drug-vitamins interaction in pre-clinical experiments.

Cross Talk and Interference Enhance Information Capacity of a Signaling Pathway

A recurring motif in gene regulatory networks is transcription factors (TFs) that regulate each other and then bind to overlapping sites on DNA, where they interact and synergistically control transcription of a target gene. Here, we suggest that this motif maximizes information flow in a noisy network. Gene expression is an inherently noisy process due to thermal fluctuations and the small number of molecules involved. A consequence of multiple TFs interacting at overlapping binding sites is that their binding noise becomes correlated. Using concepts from information theory, we show that in general a signaling pathway transmits more information if 1), noise of one input is correlated with that of the other; and 2), input signals are not chosen independently. In the case of TFs, the latter criterion hints at upstream cross-regulation. We demonstrate these ideas for competing TFs and feed-forward gene-regulatory modules, and discuss generalizations to other signaling pathways. Our results challenge the conventional approach of treating biological noise as uncorrelated fluctuations, and present a systematic method for understanding TF cross-regulation networks either from direct measurements of binding noise or from bioinformatic analysis of overlapping binding sites.

The Research on Detection Method of Multi-Gas Sensor Based on BP Neural Network

In the paper the multi-gas sensor are detected aimed at the problem of cross interference between the eight kinds of toxic and harmful gases. The cross sensitive characteristics between the different gases are determined through the interference degree, and the cross sensitive model with the environment parameters is built. The BP network is designed with the Matlab toolbox and the data are trained. The results show that the forecast accuracy of the gas concentration can be improved effectively, and the average relative error is reduced. So the new method is put forward to solve the cross interference problem of dangerous chemicals gas effectively.