Pass Filter Research Articles

Harmonic elimination using SW based HSAPF system and evaluation of compensation effect employing ADALINE-DFFRLS algorithm

This paper presents a low-rated midpoint DC-link capacitor hybrid shunt active power filter (HSAPF) embedded with sliding window (SW) based harmonic detection method for power quality enhancement in a medium-voltage distribution network. The novel composite current control technique utilizes SW based high pass filtering for determining the reference voltages, SW based low pass filtering for absorbing the negative sequence currents of 5th order harmonic. In this study, an additional effort has been made to evaluate the compensation effect of the HSAPF system by using a combinational adaptive linear neural network and dynamic forgetting factor recursive least squares (RLS) (ADALINE-DFFRLS) algorithm. Due to the utilization of dynamic forgetting factor (DFF) mechanism, the DFFRLS based weight updating rule shows faster and accurate estimation results in noisy environments compared to the conventional RLS. The performance of the proposed ADALINE-DFFRLS estimation algorithm is compared with the ADALINE-RLS to exemplify its faster-tracking capability. Extensive simulation is carried out to show the compensating performance of the HSAPF system employing SW based proposed controller under different critical conditions. Additionally, an experimental setup is developed for validation of the proposed control strategy in the real-time using a Spartan 3A DSP processor.

Experimental Verification of Singularity-Robust Torque Control for a 1.2-Nm–5-Hz SGCMG

A single gimbal control moment gyro (SGCMG) has been designed and developed as a torque amplifier to generate 1.2-Nm–5-Hz gyroscopic torque for the angle deviation of 45°. Since the SGCMG is aimed to generate the torque accurately in the designated direction, the return of the gimbal from the disturbance should be guaranteed within a desired frequency. However, unexpected axial drift exists and leads to a null motion under the torque control scheme. Therefore, this paper identifies the cause of axial drift and proposes a new torque control technique with two phases of compensation. Compensator I is designed to eliminate the nonlinear axial drift modeled as a sigmoidal function through an empirical identification process. Compensator II reduces other uncertainties by integrating high-pass filtering, recursive least square, all pass filtering, and moving average filtering (MAF) process. Finally, the proposed control scheme has been verified through experimental studies.

Regional and residual gravity anomaly separation using the singular spectrum analysis-based low pass filtering: a case study from Nagpur, Maharashtra, India

We present here a singular spectrum analysis (SSA)-based low pass filtering algorithm for regional and residual gravity anomaly separation. The data adaptive decomposition in SSA frequency filtering algorithm facilitates reduction of the artefacts in the filtering of the non-linear and non-stationary gravity data. Initially, the method was tested on synthetic gravity data representing combined response of regional and residual components derived from the geological structures like infinite horizontal layers, intrusive dykes, deep-seated faults and volcanic intrusive bodies and compared with fast Fourier transform (FFT) wavenumber and wavelet-based filtering techniques. The results show that SSA-based filtered output exhibits a better match with pure synthetic data than the output generated from the FFT and wavelet filtering methods. The underlying method was then applied to two parallel gravity profiles of real data from the Umred coalfield, Nagpur, Maharashtra, India. Further, the SSA-based filtered regional anomaly was modelled using Geosoft GM-SYS software to construct the model of crustal structure of the study region. In essence, the modelling results suggest the following: (i) a basin-type graben structure with variable trap and sedimentary thicknesses and (ii) deep seated faults on either sides of the basin. These results correlate fairly well with known regional geology attesting the authenticity of the regional models generated from the two gravity profiles, which also agree well with each other. We, therefore, conclude that the SSA-based filtering technique is robust for regional gravity anomaly separation and could be effectively exploited for filtering other geophysical data.

Investigating Image Fusion Techniques on CHRIS/Proba Space Borne Hyperspectral Data for Material Identification

Image fusion can be defined as the process of combining information from two images with unique characteristics to obtain a resultant image which has an assemblage of qualities of both the inputs. Of late, many studies were carried out in fusing multispectral data with panchromatic data, but fusion of hyperspectral data with multispectral data is a topic of interest till date. In the present study, image fusion technique was used to obtain a spatially and spectrally rich hyperspectral (HS) image which can aid in improved material identification. Two conventional pixel basedfusion techniques namely – Gram Schmidt (GS) fusion and High Pass Filtering (HPF) technique were used for fusing the HS CHRIS image with the multispectral (MS) LISS IV image. An overall spectral, spatial/visual and quantitative analysis was carried out to examine the quality offused images. Quantitative analysis of the individual bands was made using SNR and entropy measures. Classification of the fused images helped in identifying five different concrete materials and four different vegetation types within the study area. An overall classification accuracy of 88.33% was obtained using GS fused image, 79.25% with HPF fused image and 73.66% with the CHRIS data.

Rolling element bearings localized fault diagnosis using signal differencing and median filtration

With the increase complexity of bearings’ processing algorithms and the growing trend of using computationally demanding algorithms, it is advantageous to provide analysts with a simple to use and implement algorithm. In this spirit, this paper combines simple functions to provide machine condition analysts with the capacity to diagnose bearing faults without all the complexity and jargon that comes with existing methods. The paper proposes a simplified surveillance and diagnostic algorithm for diagnosing localized faults in rolling element bearings using measured raw vibration signals. The proposed algorithm is based on analyzing the frequency content obtained from applying a median filter on the squared derivative signal (first or higher derivatives) of the vibration signal. The combination of signal differencing and median filters provides a squared envelope signal, which can be used directly to diagnose faults. Signal differencing gives a measure of jerk forces and lifts the high frequency content of the signal. To select the optimum order of differentiation, Kurtosis and maximum correlated kurtosis (MCK) are proposed. Median filter usage represents a better alternative of normal low pass filtration. This completely suppresses impulses with large magnitudes, which may interfere with the diagnosis. The length of the median filter (odd number 3, 5, 7 etc.) is selected as such to include the first 10 harmonics of the defect frequency. Simulated signals are used to demonstrate the efficiency of the proposed algorithm and give insights into the choices of the differentiation and smoothening orders. The proposed processing algorithm gives a first measure (surveillance) for detecting localized faults in rolling element bearings in a very simple way and can be employed in online learning and diagnosis systems. Results obtained from applying the algorithm on complex vibration signals from two types of gearboxes are compared with a well-established semi-automated technique with good correspondence.

Detection of Coastal Damage using Differences in Automatically Generated Digital Surface Models (DSMs): Application to the 2011 Off the Pacific Coast of Tohoku Earthquake Tsunami

Udo, K.; Takeda, Y., and Koshimura, S., 2018. Detection of coastal damage using differences in automatically generated digital surface models (DSMs): Application to the 2011 Off the Pacific Coast of Tohoku Earthquake Tsunami. In: Shim, J.-S.; Chun, I., and Lim, H.S. (eds.), Proceedings from the International Coastal Symposium (ICS) 2018 (Busan, Republic of Korea). Journal of Coastal Research, Special Issue No. 85, pp. 696–700. Coconut Creek (Florida), ISSN 0749-0208.The detection of coastal damage due to the 2011 Off the Pacific Coast of Tohoku Earthquake Tsunami on the southern Sendai Coast was attempted via state-of-the-art remote sensing technology using ALOS PRISM satellite images with a spatial resolution of 2.5 m. Digital surface models (DSMs) were generated semi-automatically, and their accuracies were confirmed via comparisons with digital elevation models generated from aerial laser measurements. The differences between the DSMs prior to and after the tsunami were analyzed statistically for each type of land cover: residential districts, rice fields, coastal forests, and beaches. It was demonstrated that the damage to the coastal forests and residential districts could be detected though the damage in the low land area was difficult to be detected because of its small undulations in topography. Low pass filtering was employed to remove the jitter noise; however, the major characteristics such as damage in the coastal forests and residential areas were not changed by the filtering; that is, the major statistical characteristics could be detected without filtering.

Laser induced fluorescence measurement of liquid film thickness and variation in Taylor flow

In the present work, experiments are done to understand the distribution of liquid film in Taylor flows occurring in small circular mini channels using laser-induced fluorescence. Gas–liquid Taylor flow is generated in 3 different channels of inner diameter 1.5, 2.1 and 3.1 mm to understand the effect of flow parameters and nature of forces on the liquid film thickness. Rhodamine-B, a fluorescent dye is mixed with water, the primary phase in the two-phase mixture and is excited by a pointed laser beam of wavelength 531 nm. The liquid film thickness with the excited fluorescent dye emits light at 610 nm which is captured using a CMOS high-speed camera. A long pass filter is used to filter the reflected laser light before being captured by the CMOS sensor camera. Subsequently, the image obtained is processed with a set of image processing techniques to determine the liquid film thickness. Different slug shapes are obtained for various combinations of flow velocities and are found to depend on the Bond number. Further, it is also found from the experiments that asymmetry in the flow regime is found to depend on the capillary forces acting on the flow and it increases with the capillary number. The film thickness is also found to vary across the air slug length and its distribution along the flow length is also presented.

Experimental study of a compact electrostatically assisted air coarse filter for efficient particle removal: Synergistic particle charging and filter polarizing

Efficient particle removal technology with minimal pressure drop is urgently needed for both air purification and energy conservation. We developed a compact electrostatically assisted air (cEAA) coarse filter, whose particle removal performance is enhanced by the synergistic effect of a corona charging field and a polarizing field. We investigated the influences of charging voltage (U), polarizing distance (dpl), effect of dielectric and geometric characteristics of the filter material on fraction filtration efficiency of PM0.01∼5, net ozone production, pressure drop and power dissipation of the cEAA coarse filter. Our experiments were performed in a ventilation duct using ambient air particulate matter. We found an optimal U between the corona charging onset voltage and the polarizing onset voltage that enhances particle filtration efficiency with nearly no net ozone production and low energy consumption. Single pass filtration efficiency for 0.3 μm particles increased from 4% to 69% with U varying from 0 to +9 kV (dpl = 3.5 cm). We found that filter material of larger relative dielectric constant or larger tortuosity yields higher filtration efficiencies. During a 458-h long-term operating period, the single pass filtration efficiency of the cEAA coarse filter did not decrease but increased slightly, and the pressure drop grew from 14.3 Pa to 31.5 Pa. We present a design strategy for a cEAA coarse filter with less than 30 Pa pressure drop at 1 m/s air velocity.

Design and characterization of Au/In4Se3/Ga2S3/C field effect transistors

Abstract In the current work, the structural and electrical properties of the In4Se3/Ga2S3 interfaces are investigated. The X-ray analysis which concern the structural evolutions that is associated with the substrate type has shown that the hexagonal κ-In2Se3 and the selenium (rhombohedral) rich orthorhombic In4Se3 phases of InSe are grown onto glass and gold substrates, respectively, at substrate of temperature of 300 °C in a vacuum media. The coating of the κ-In2Se3 and of In4Se3 with amorphous layer of Ga2S3 is accompanied with uniform strain. The In4Se3/Ga2S3 interface is found to be of attractive quantum confinement features as it exhibited a conduction and valence band offsets of 0.20 and 1.86 eV, respectively. When the Au/In4Se3/Ga2S3 interface was contacted with carbon metallic point contact, it reveals a back to back Schottky hybrid device that behaves typically as metal–oxidesemiconductor field effect transition (MOSFET). The depletion capacitance analysis of this device revealed built in voltage values of 1.91 and 1.64 V at the Au and C sides, respectively. The designed MOSFET which is characterized in the frequency domain of 0.01–1.80 GHz is observed to exhibit, resonance-anti-resonance phenomena associated with negative capacitance effect in a wide domain of frequency that nominate it for applications in electronic circuits as parasitic capacitance minimizer, bus switching speed enhancer and low pass/high pass filter at microwave frequencies.

Investigating the effects of graphene-based superstrate on characteristic of microwave filters

This paper presents a study based on changes in the cut-off frequency and sharpness of different types of filter by loading with glass and graphene–glass superstrate. Design and fabrication of four basic types of microwave filter – low-pass, high-pass, band pass, and band stop filter are presented and S-parameters are measured with superstrate. The impact of superstrate on the filter characteristics such as cut-off frequency, bandwidth, and sharpness are analyzed experimentally by comparing these characteristics for without superstrate and with superstrate. The superstrate loading resulted in the decrease of cut-off frequency for low-pass and high-pass filter, whereas the bandwidth is decreased for band pass filter and band stop filter with larger shift in high cut-off frequency. Such effects have been confirmed by the simulation of low-pass filter and band pass filter on placing a glass. It is estimated from the filter responses that graphene–glass has conducting as well as dielectric nature compared to glass in the frequency range of study. It has been shown that the cut-off frequency and bandwidth can be tuned by dielectric kind of superstrate without varying the physical dimension of filter.

Transformation of Ladder Based All Pass and Biquad Filters into Active All Pass and Biquad Filter using CFOA

In this paper ladder based all pass and biquad filters are transformed into CFOA based all pass and biquad filters. The ladder based approach is used for design of prototypes. The new circuits have attractive properties of greater linearity, high dynamic rate, high slew rate and high signal bandwidth. A new technique for the conversion has been proposed. The technique uses signal flow graph and converts the existing LC ladder based filter into CFOA based configurations. The design of all pass and Biquad filter has been realized using the proposed technique. The proposed configuration is implemented using CFOA as an active device and all the capacitors are grounded. The new configurations are suitable for various signal processing applications. Simulation has been carried out using simulation software PSpice (v10.2). The simulation results have been demonstrated and discussed.

The PIV study of air flow past the counter-swirler 53983

PIV (particle image velocimetry) measurement of the air flow past a counter-swirler 53983 (anticlockwise swirler surrounded by clockwise swirler) is performed. The measurement is focused to an area at the boundary between the inner swirling jet and the outer one rotating oppositely. The Reynolds number Re based on the inner swirler diameter ranged form 1.2·103 to 2.1·104. By using band pass filtering the shear layer and vortices in the contact region between counter-swirling jets is highlighted. The shear layer between these regions shortens and decays into vortices as Reynolds number increases.

Optical SAR Images Fusion: Comparative Analysis of Resulting Images Data

Image fusion is a useful tool for integrating low spatial resolution multispectral (MS) images with a high spatial resolution panchromatic (PAN) image, thus producing a high resolution multispectral image for better understanding of the observed earth surface. A main proposed the research were the effectiveness of different image fusion methods while filtering methods added to speckle suppression in synthetic aperture radar (SAR) images. The quality assessment of the filtering fused image implemented by statistical parameter namely mean, standard deviation, bias, universal index quality image (UIQI) and root mean squared error (RMSE). In order to test the robustness of the image quality, either speckle noise (Gamma map filter) is intentionally added to the fused image. When comparing and testing result, Gram Scmidth (GS) methods have shown better results for good colour reproduction, as compared with high pass filtering (HPF). And the other hands, GS, and wavelet intensity hue saturation (W-IHS) have shown the preserving good colour with original image for Landsat TM data.

Weight and Diameter Estimation Using Image Processing and Machine Learning Techniques on Apple Images

Classification of table fruits according to size is traditionally hand made. But human factors are the cause of faulty classifications. Automatically performing this process with the machines is important in terms of speeding up the process, reducing costs, and minimizing errors. In this study, weight and diameter estimations were made on Starking type apples using image processing techniques. Firstly 50 photographs were taken with NIR camera and 830nm long pass filter. Afterwards, edge detection algorithms and morphological operations were performed on the images to obtain the boundaries of the images. Diameter and area information obtained from the binary image were used as attributes. These attributes were given as input to Linear Regression method and estimated. As a result, 93% of the diameters of the apples and 96.5% of the weights could be estimated.

OBIST methodology incorporating modified sensitivity of pulses for active analogue filter components

ABSTRACTIn this paper, oscillation-based built-in self-test method is used to diagnose catastrophic and parametric faults in integrated circuits. Sallen–Key low pass filter and high pass filter circuits with different gains are used to investigate defects. Variation in seven parameters of operational amplifier (OP-AMP) like gain, input impedance, output impedance, slew rate, input bias current, input offset current, input offset voltage and catastrophic as well as parametric defects in components outside OP-AMP are introduced in the circuit and simulation results are analysed. Oscillator output signal is converted to pulses which are used to generate a signature of the circuit. The signature and pulse count changes with the type of fault present in the circuit under test (CUT). The change in oscillation frequency is observed for fault detection. Designer has flexibility to predefine tolerance band of cut-off frequency and range of pulses for which circuit should be accepted. The fault coverage depends upon the required tolerance band of the CUT. We propose a modification of sensitivity of parameter (pulses) to avoid test escape and enhance yield. Result shows that the method provides 100% fault coverage for catastrophic faults.

Diagnosis of stator shorted-turn faults in induction machines using discrete wavelet transform

Incipient detection and diagnosis of stator winding shorted-turn faults in induction machines is essential for reliable and economical operations in industries. The problem of detecting shorted-turn faults in stator windings has been difficult. Although, from the supply currents, major winding faults can easily be detected, minor faults with less than five per cent of winding turns are not easily detectable. If not detected early, such faults can lead to major winding faults which may further lead to the disruption of the machine and causes production shutdowns. This paper describes the discrete wavelet transform (DWT) based diagnosis technique that analyses stator currents under faulty (stator shorted-turn) and healthy conditions. The developed technique depends on the band pass filtering carried out by the DWT, facilitating the extraction of the harmonic components produced by the shorted-turn faults. The discrepancies energy spectrum for three frequencies from the residual of de-noising analysis enables us to classify the fault index. From 38 seconds, the shorted turn begins to show significant difference in the energy spectrum, and if this is not detected in time, it may lead to a more serious fault.

Flow cytometry to estimate the cell disruption yield and biomass release of Chlorella sp. during bead milling

A number of visual, chemical and fluorescence-based methods are generally employed for monitoring of algae cell growth, culture health and biomass concentration. These methods are often time-consuming, demand destructive and high volume sampling. Rapid, efficient, cost-effective and automated methods which facilitate high-throughput and non-destructive sampling would highly benefit microalgae biotechnology. It is known in literature that with flow cytometry it is possible to monitor microalgae growth and microalgae culture health. Flow cytometry, however, has not been used to estimate biomass release and cell disruption yield. In this study with representative cultures of Chlorella sp., flow cytometry data were generated by a long pass filter (>670nm) and proved to be a promising technique to rapidly evaluate these parameters during cell disruption by bead milling. Both a laboratory and a commercial culture of Chlorella were bead milled. Prior to and during bead milling, biomass release was evaluated gravimetrically and the cell count was determined via hemocytometer manual counting and 3 flow cytometry methods: 1) direct event count of a certain population, 2) quadrant-upper right event count of a long pass filter (>670nm) and 3) a calculation based on the long pass filter data. The data of all methods were compared and correlated to gravimetric biomass release data. Manual counting resulted in an underestimation of the cell disruption yield as one of the Chlorella cultures manual counts did not agree with biomass release data. Good correlations for both cultures were found for cell disruption yield calculations based on flow cytometry data and gravimetric biomass release data. Flow cytometry is therefore an efficient analytical method to rapidly screen disruption yields during cell disruption in microalgae and can be a substitute for the time-consuming direct methods (e.g. gravimetric, manual counting) for estimating biomass release and cell disruption yield.

Luminescence of thermally altered human skeletal remains

Literature on luminescent properties of thermally altered human remains is scarce and contradictory. Therefore, the luminescence of heated bone was systemically reinvestigated. A heating experiment was conducted on fresh human bone, in two different media, and cremated human remains were recovered from a modern crematory. Luminescence was excited with light sources within the range of 350 to 560 nm. The excitation light was filtered out by using different long pass filters, and the luminescence was analysed by means of a scoring method. The results show that temperature, duration and surrounding medium determine the observed emission intensity and bandwidth. It is concluded that the luminescent characteristic of bone can be useful for identifying thermally altered human remains in a difficult context as well as yield information on the perimortem and postmortem events.

POINT CLOUD DERIVED FROMVIDEO FRAMES: ACCURACY ASSESSMENT IN RELATION TO TERRESTRIAL LASER SCANNINGAND DIGITAL CAMERA DATA

Abstract. The use of image sequences in the form of video frames recorded on data storage is very useful in especially when working with large and complex structures. Two cameras were used in this study: Sony NEX-5N (for the test object) and Sony NEX-VG10 E (for the historic building). In both cases, a Sony α f = 16 mm fixed focus wide-angle lens was used. Single frames with sufficient overlap were selected from the video sequence using an equation for automatic frame selection. In order to improve the quality of the generated point clouds, each video frame underwent histogram equalization and image sharpening. Point clouds were generated from the video frames using the SGM-like image matching algorithm. The accuracy assessment was based on two reference point clouds: the first from terrestrial laser scanning and the second generated based on images acquired using a high resolution camera, the NIKON D800. The performed research has shown, that highest accuracies are obtained for point clouds generated from video frames, for which a high pass filtration and histogram equalization had been performed. Studies have shown that to obtain a point cloud density comparable to TLS, an overlap between subsequent video frames must be 85 % or more. Based on the point cloud generated from video data, a parametric 3D model can be generated. This type of the 3D model can be used in HBIM construction.

Micro EEG/ECG signal’s chopper-stabilization amplifying chip for novel dry-contact electrode**Project supported by the National Natural Science Foundation of China (Nos. 61527815, 31500800, 61501426, 61471342), the National Key Basic Research Plan (No. 2014CB744600), the Beijing Science and Technology Plan (No. Z141100000214002), and the Chinese Academy of Sciences’ Key Project (No. KJZD-EW-L11-2).

Facing the body’s EEG (electroencephalograph, 0.5–100 Hz, 5–100 μV) and ECG’s (electrocardiogram, , 0.01–5 mV) micro signal detection requirement, this paper develops a pervasive application micro signal detection ASIC chip with the chopping modulation/demodulation method. The chopper-stabilization circuit with the RRL (ripple reduction loop) circuit is to suppress the ripple voltage, which locates at the single-stage amplifier’s outputting terminal. The single-stage chopping core’s noise has been suppressed too, and it is beneficial for suppressing noises of post-circuit. The chopping core circuit uses the PFB (positive feedback loop) to increase the inputting resistance, and the NFB (negative feedback loop) to stabilize the 40 dB intermediate frequency gain. The cascaded switch-capacitor sample/hold circuit has been used for deleting spike noises caused by non-ideal MOS switches, and the VGA/BPF (voltage gain amplifier/band pass filter) circuit is used to tune the chopper system’s gain/bandwidth digitally. Assisted with the designed novel dry-electrode, the real test result of the chopping amplifying circuit gives some critical parameters: 8.1 μW/channel, 0.8 μVrms (@band-width = 100 Hz), 4216–11220 times digitally tuning gain range, etc. The data capture system uses the NI CO’s data capturing DAQmx interface, and the captured micro EEG/ECG’s waves are real-time displayed with the PC-Labview. The proposed chopper system is a unified EEG/ECG signal’s detection instrument and has a critical real application value.