Pass Filter Research Articles

Longevity of size-dependent particle removal performance of do-it-yourself box fan air filters.

Filtration performance of do-it-yourself (DIY) box fan filters deployed across a university campus was assessed over an academic year. Four DIY air filters were constructed from box fans and air filters with a minimum efficiency reporting value (MERV) of 13 and deployed in four spaces (two laboratories that include sources of particles and two offices). They were operated 9 hours daily with a programmable timer and were continuously monitored with power meters. Particle concentrations in the spaces were continuously monitored with low-cost nephelometers. The particle size dependent clean air delivery rate (CADR) and single pass filtration efficiency for each box was measured in a laboratory before deployment and every 10 weeks, for a total of five measurements over 40 weeks. We find that these DIY box fan filters maintain robust performance over time, with each air filter maintaining at least 60% of its initial CADR at the end of the 40 week study even with daily operation in environments with modest particle concentrations. CADR values for particles of 1.0-3.0 μm optical diameter averaged 34% higher than CADR values for 0.35-1.0 μm particles, aligning with MERV 13 filter size-dependent filtration expectations. Reductions in CADR over time were attributed to a reduction in filtration efficiency, likely due to a loss of filter electrostatic charge over time. There was no strong indication that increased resistance due to particle accumulation on filters appreciably decreased flow rates over time for any of the fans. The long-term robustness of DIY box fan air filters demonstrates their validity as a cost-effective, high performance, alternative to portable high efficiency particulate air (HEPA) filters.

A 2.4 GHz High-Efficiency Rectifier Circuit for Ambient Low Electromagnetic Power Harvesting.

A novel 2.4 GHz high-efficiency rectifier circuit suitable for working under very-low-input electromagnetic (EM) power conditions (-20 to -10 dBm) is proposed for typical indoor power harvesting. The circuit features a SMS7630 Schottky diode in a series with a voltage booster circuit at the front end and a direct-current (DC)-pass filter at the back end. The voltage booster circuit consists of an asymmetric coupled transmission line (CTL) and a high-impedance microstrip line (of 100 Ω instead of 50 Ω) to significantly increase the potential at the diode's input, thereby enabling the diode to operate effectively even in very-low-power environments. The experimental measurements show that the microwave direct-current (MW-DC) conversion efficiency of the rectifier circuit reaches 31.1% at a -20 dBm input power and 62.4% at a -10 dBm input power, representing a 7.4% improvement compared to that of the state of the art. Furthermore, the rectifier circuit successfully shifts the input power level corresponding to the peak rectification efficiency from 0 dBm down to -10 dBm. This design is a promising candidate for powering low-energy wireless sensors in typical indoor environments (e.g., the home or office) with low EM energy density.

Mental Stress Prediction Using Machine Learning on Real Time Dataset

Mental stress is a significant issue affecting individuals across all age groups in today's society. The impact of stress extends beyond mental well-being and can lead to various chronic illnesses, including depression, malignancy, and cardiovascular disease (CVD). Addressing mental stress and implementing strategies for stress management and prevention are crucial not only for mental well-being but also for reducing the risk of associated chronic illnesses. In this paper, we are focussing of the problem of mental stress in today's society and the significance of early prediction and management. The use of Random Forest (RF) method with enhanced band pass filtration technique on ECG data for predicting stress levels is a promising approach. Achieving a 96.73% accuracy in stress categorization, along with improvements over prior research results, highlights the effectiveness of the proposed model. The main contribution of the research work is that the results of the model are validated using real-time datasets which further strengthens its reliability and applicability in practical scenarios.

Reliable human authentication using AI-based multibiometric image sensor fusion: Assessment of performance in information security

Reliable human authentication is essential for assuring the availability, confidentiality, and integrity of sensitive data and resources in the field of information security. Due to the vulnerabilities of conventional authentication techniques like passwords and PINs, interest in biometric-based authentication systems has developed. To get over this, we suggest an efficient voice and iris recognition-based multimodal biometric verification strategy for human authenticating tools. We first collect the voice and iris datasets from 150 people. Then, we used a median filter and high pass filter to preprocess the voice and iris data. The features of voice identification are extracted using the shifted delta cepstral coefficient (SDCC) and the Mel frequency discrete wavelet coefficient (MFCC), and these two coefficients are evaluated. The outcomes of the extraction of iris identification features using Local binary pattern (LBP) and Speeded robust features (SURF) are evaluated. The classifier Fine Tuned Cuckoo Search Optimized Convolutional Neural Network (FCSO-CNN) performs voice and iris recognition modalities. Voice and iris biometric systems may be combined into a single multimodal biometric system by fusing their respective feature sets and scoring algorithms. The results of the computer simulation demonstrate that for speech recognition, using the SDC and MFC coefficients produces better results, while for iris recognition, using the LBP and FCSO-CNN experiment produces superior outcomes. Additionally, the scores fusion works superior to other scenarios in the proposed multimodal biometrics system. The suggested system provides a dependable and strong solution for human identification, assisting in the improvement of security measures across a variety of industries, including financial institutions, governmental agencies, and the defense of key infrastructure.

Efficient Performance Analysis of Image Enhancement Filtering Methods Using MATLAB

Image enhancement is both an art and a science, playing a pivotal role in enhancing the quality of high-resolution images like those captured by digital cameras. Its primary goal is to unveil hidden details within an image and augment the contrast in images with low contrast. This method offers a plethora of options for elevating the visual appeal of images, making it an indispensable tool in numerous applications that face challenges such as noise reduction, degradation, and blurring. In this paper, we implemented frequency domain low pass filters like ideal low pass filter, Butterworth low pass filter and Gaussian low pass filters with execution time using MATLAB. The Butterworth low pass filter given better results than other two with less execution time.

Power Performance Evaluation of Standalone Renewable Energy Source Energy Management Using Pass Filter

Hybrid energy storage systems have shown promise in enhancing solar panel systems reliability and efficiency. However, managing the power distribution balance with multiple energy storage units remains a challenge. This research addresses power distribution balancing during solar irradiation intermittency by employing a first-order filter with lowpass and highpass characteristics. The study aims to investigate energy and power management issues for off-grid electrical systems using this filter. Results from numerical simulations and experiments with a hybrid energy storage setup comprising a battery and supercapacitor show that the first-order filter effectively allocates the first-order signal to the main energy storage and subsequent orders to the supporting energy storage. During increased intermittency, the battery contributes 62 W and stores 387 W, while the supercapacitor contributes 167 W and stores 297 W. Conversely, during reduced intermittency, the battery stores 390 W and contributes 62 W, and the supercapacitor stores 295 W and contributes 164 W. The findings demonstrate the filter's efficacy in optimizing power distribution balance within hybrid energy storage systems. However, using the supercapacitor as the main energy storage does not result in higher power efficiency compared to the battery. In conclusion, the First Order Filter presents a viable solution for addressing power distribution challenges in hybrid energy storage systems, contributing to improved energy and power management for off-grid electrical systems. Further research on cost-effectiveness, maintenance, and environmental impact is warranted for practical implementation

Simulation of Active Sallen Key Notch Filter Circuit Using Circuit Wizard and Its Real Testing

An electronic circuit that functions to block or hold signals with intermediate frequencies (median) and will forward signals between low frequencies and high frequencies is the definition of a Notch Filter. The Band Stop Filter, also often referred to as the Notch Filter, is a combination of a Low Pass Filter and a High Pass Filter connected in parallel. This connection differs from the Band Pass Filter, which connects the Low Pass Filter and High Pass Filter in series. This study aims to discuss the simulation of the Sallen-key notch filter Circuit. The author also conducts real simulations to prove the Circuit by changing or adjusting the value of the components installed in the Circuit so that the frequency response is according to the target. The purpose and role of the Sallen-key notch filter and the working principle of the theory of each filter used. The research method used in the research work is to carry out virtual simulations using virtual simulators and live simulations

Preliminary Analysis on the Effect of Different Denoising Techniques towards Texture Features of MRI Images of Alzheimer’s Disease

Early detection of Alzheimer’s disease (AD) has become one of the major research topics nowadays. The utilization of the computerized system may help medical experts to better understand and analyse the magnetic resonance imaging (MRI) images of AD patients for early detection. One of the commonly steps taken for the analysis of the image is image denoising using certain filters. However, finding shows that previous researchers use different approaches. This study aims to analyse the effect of different denoising techniques towards detection of Alzheimer’s disease. Data of two different groups (AD patients and Normal Control) were collected from Alzheimer's Disease Neuroimaging Initiative (ADNI). Then brain extraction and skull stripping were performed. Several image denoising techniques were implemented for both groups namely median filter, Wiener filter, histogram equalization filter and Gaussian low pass filter. After that, all images underwent texture feature extraction process and analysis were made to see the effect of those denoising techniques towards the features of Gray-Level Co-occurrence Matrix (GLCM) extracted which are the contract, correlation, energy and homogeneity features. The result shows that the use of mentioned denoising filters do not give effect to the extracted features. All values of contrast, correlation, energy and homogeneity cannot clearly distinguish between AD and NC groups. Without any filters on the other hand, contrast feature gives the best output in distinguishing between AD and NC groups with the normalized value of 0.1. The result from this study may help in thorough investigation of other features or hybrid features that could be used for the purpose of detection and classification of AD.

High-Q terahertz bandstop filter via cuboid frame structure

A terahertz (THZ) bandstop filter can be used to filter interference signals in a filter passband. The quality factor (Q) is the most important index in evaluating the transmission performance of the filter. Usually, a higher Q value, a narrow bandwidth and a larger stopband slope ensures good filtering accuracy and transmission response. However, the Q value taken from metamaterial structures designed on the plane is only ever in single digits, resulting in a less than satisfactory filtering performance. Herein, a high-Q THZ bandstop filter based on metamaterials was proposed. To fabricate this 3D metamaterial structure, a microtopographic substrate-guided method with feasible and high accuracy capacities was proposed. As a result, it is ascertained that the device is in the filtering state in the range 1.038–1.102 THz while it is stopped in the range 1.062–1.066 THz. The similarity between the experimental and simulated transmissions is up to 86.32%, indicating that the fabricating method possesses high accuracy. Accordingly, the Q value was calculated to be as high as 532. In future, the bandstop filter with this record Q value can be widely used in THZ detection, imaging and sensing. Meanwhile, the proposed fabrication method is effectively applied to a 3D metamaterial and a THZ device as well.

Single CDBA-based grounded parallel lossy inductor simulator circuits

Two new configurations for the realization of lossy grounded inductor each employing one current differencing buffered amplifier (CDBA), three resistors, a voltage follower and one grounded capacitor are presented. The realized inductances from the proposed configurations have independent tunability through a single resistor. The proposed circuits make use of the intrinsic current differencing property of CDBAs by not leaving any of its input terminals open or connected to ground. Both the presented circuits use grounded capacitor (which is particularly attractive for integrated circuit implementation) connected at the Z-terminal of CDBA which may also absorb the parasitic capacitance. The proposed lossy inductors can be used in applications such as low frequency sinusoidal oscillator, low pass filter (LPF) and band pass filter (BPF). Such examples may be suitable from the viewpoint of biomedical instrumentation and geo-physical applications. Non-ideal analysis has been carried out to support the theoretical propositions for both the proposed circuits. PSPICE simulation results with CMOS CDBA have been presented to establish the workability of the proposed lossy inductor structures. Experimental results using commercially available AD844 ICs have also been included to demonstrate the viability of the proposed lossy inductors based on CDBAs.

Manual single lumen alternating micro-batch dialysis achieves reliable clearance via diffusion.

Acute kidney injury is a cause of preventable deaths in low resource settings due to lack of dialysis access and cost. A manual single lumen alternating micro-batch (mSLAMB) dialysis technique performs kidney replacement therapy using single lumen access, low-cost bags/tubing, intravenous fluids, anda filter without electricity, a battery, or a pump. We propose a protocol whereby mSLAMB can perform diffusive clearance simply and efficiently to bring dialysis to underserved populations. Expired packed red blood cells mixed with crystalloid solution were spiked with urea and anticoagulated with heparin. A Static diffusion Technique (with short flushes of fluid before each filter pass) was compared to a Dynamic diffusion Technique (with fluid running through the filter during the forward pass) to assess urea and potassium clearance. Passive ultrafiltration was the difference between the 200 mL batch volume and volume returned to the blood bag per cycle. Five cycles achieved urea reduction ratios (URR) between 17-67% and potassium clearance of 18-60%, with higher percentagesachieved from higher proportions of batch volume dialyzed to patient volume. Dynamic Technique increased clearance over the Static Technique. Passive ultrafiltration volumes were 2.5-10% of batch volume. mSLAMB dialysis performs diffusive clearance and passive ultrafiltration efficiently, while preserving resources and available manpower. mSLAMB is a dialysis technique that can perform efficient diffusive clearance and passive ultrafiltration without electricity, batteries, or a pump. With basic medical supplies and limited manpower, mSLAMB is a cost-effective means of providing emergency dialysis in low resource areas. We propose a basic algorithm for safe and cost-effective dialysis for people of different ages and sizes.

Visible-light-induced strong oxidation capacity of metal-free carbon nanodots through photo-induced surface reduction for photocatalytic antibacterial and tumor therapy

Biocompatible metal-free carbon dots (CDs) with good photo-induced strong oxidation capacity in aqueous solutions are scarce for high-performance photocatalytic antibacterial and tumor therapy. In this work, we achieved effective visible light-induced cell death and antibacterial performance based on biocompatible metal-free CDs. The visible-light-induced reducing ability of the surface electron-withdrawing structure of the CDs allowed for the remaining photo-induced holes with high oxidation capacity to oxidize water molecules and generate hydroxyl radicals. Antibiotic-resistant bacteria were effectively inhibited by the CDs under xenon lamp irradiation with 450 nm long pass filter. Moreover, CD-based tumor photocatalytic therapy in mice was achieved using a xenon lamp with 450 nm long pass filter (0.3 W cm−2).

Couette flow fluorescence detected linear dichroism for analytes in lipid bilayers.

Membranes are important sites of intermolecular interactions in biological systems. However, they present significant analytical challenges as they contain multiple analytes and are dynamic in nature. In this work, we show how a Jasco J-1500 circular dichroism spectropolarimeter can be used with a microvolume Couette flow cell and appropriate cut-off filters to measure excitation fluorescence detected linear dichroism (FDLD) of fluorophores embedded in liposomal membranes. The result is a spectrum that selectively probes the fluorophore(s) and eliminates the scattering that is apparent in the corresponding flow linear dichroism (LD) spectrum. The FDLD spectrum is opposite in sign from the LD spectrum with relative magnitudes modified by the quantum yields of the transitions. FDLD thus enables analyte orientations to be identified in a membrane. Data for a membrane peptide, gramicidin, and two aromatic analytes, anthracene and pyrene, are presented. Issues with the "leakage" of photons by the long pass filters used is also discussed.

Characteristic of Asphalt Mixture using Fly Ash and Bottom Ash Substitution in Reducing Environment Pollution

One of the waste materials produced by industry activities is fly ash and bottom ash (FABA), it is produced by brick combustion waste. Fly ash and bottom ash waste is hazardous and toxic (B3) waste for it contains heavy metal oxides polluting the environment. Related to the condition, the output study of toxicity potential test carried out to coal ash in Nagan Raya PLTU (Electric Steam Power Plant) proving conversely. The coal ash of Nagan Raya PLTU is relatively safe to be used as construction material. The output explained that coal ash of Nagan Raya PLTU have adequate good potency to be utilized. One of coal ash potencies developed is the utilization asphalt mixture material including bottom ash as fine aggregate substitution and fly ash as filler substitution. The research aimed to find out the mixture characteristic by utilizing FABA for the road pavement of asphalt concrete layer (AC-WC) to reduce environment pollution and detect the appropriate proportion for the optimal utilization. The percentage of fine aggregate in the mixture must meet the requirement of binder as 5-15% to the weight, while the filler must meet the minimum of 75% to weight of filter pass No. 200 (0.075 mm). The test output of both mixtures by using bottom ash and fly ashin 15%-30% variation was different. The output is similar. Both of the output concluded that the optimum asphalt level was 5% and the variation of 30% bottom ash : 70% fine aggregate meet the requirement specification, while variation fly ash as subtitution Portland cement resulting that all the parameters meet the specification required by Bina Marga specification 2018.

A New Varactor-Tuned 5.8 GHz Dielectric Resonator Band-Stop Filter for ITS and C-V2X Coexistence with Vehicular DSRC

In this paper, we introduce an electronically tuneable band-stop filter based on a dielectric resonator, along with its design principles and equivalent circuit model aimed at the coexistence of intelligent transport systems (ITS) and cellular vehicle-to-everything (C-V2X) communications operating at 5.9 GHz, with the widely spread vehicular dedicated short range communications (DSRC) at 5.8 GHz. The proposed architecture involves a dielectric resonator coupled via a microstrip transmission line to a planar ring resonator. The resonance is electronically tuned by varying the bias voltage of a varactor diode placed in the ring. This design is analyzed theoretically and experimentally. For validation, a filter operating at 5.8 GHz was designed. The prototype is capable of enhancing coexistence exhibiting to features. First, when inserted into the ITS transmitter chain, it reduces unwanted transmitter emissions in the out-of-band spectrum occupied by the DSRC carriers in the 5.8 GHz frequency band of at least 25 dB, with a minimal insertion loss at 5. 9 GHz of 1.6 dB; secondly, when inserted in the ITS receiver chain, it exhibits high linearity that prevents the generation of intermodulation products falling into the filter pass band. The prototype features more than 21 dBm of third-order input intercept points, and a tuning range of 26 MHz while maintaining a minimal loaded Q factor of 93. The prototype is discussed regarding the detailed equivalent circuit parameter extraction and their dependency upon the control voltage.

Classification of Electroencephalogram Generated by Brain for Analysis of Brain Wave Signals in Students Depression

Electroencephalogram (EEG) is a brain signal processing technique used to detect abnormal brain waves. EEG signal recording uses electrodes placed on the scalp. AD620 is used to obtain high input impedance. The EEG signal is amplified by transmitting the signal into the notch filter, high pass filter and low pass filter to improve the quality of the signal such as eliminating and reducing noise. EEG recording focuses on analyzing alpha waves to determine whether the subject is students who suffering depression. For cases of depression, the lobes of the brain placed electrodes are the Occipital and Parietal lobes of the brain. The selection of participants in this study was based on the results of tests using the Student Health Questionnaire-9 (PHQ-9) method. The results obtained after recording EEG showed there was theta wave shaped abnormally large and abnormal alpha wave who shaped abnormally large.

Effect of filters on the accommodation and colour discrimination

AbstractPurpose: To evaluate the effect of coloured filters on the accommodative response and colour discrimination in young subjects.Methods: Two long pass filters (LED light reduction and 511 nm filter), two selective absorption filters (ML41 and emerald filter), and no filter condition were evaluated. The photorefractor PowerRef3 (PlusOptix) was used to measure the objective refraction at 3 different distances (40, 100, and 400 cm). The measurement obtained at 400 cm was used as a reference to calculate the accommodative response. The fixation target consisted of five letter length words (size corresponding to 6/12 Snellen) that were presented in black font over white background. Words changed with a frequency of 2 Hz according to the rapid serial visual presentation paradigm. The Cambridge Colour Test (Metropsis) was used to measure the discrimination threshold in a 10‐vector ellipse at a 3 m viewing distance. The measurement was repeated twice, and it was performed monocularly. In total, 20 healthy volunteers with no accommodation problems or colour blindness were included.Results: On average, the accommodative response with no filter condition was larger compared to the measurements with filters for 40 and 100 cm. The differences were in all cases lower than 0.25D, and differences were not statistically significant (p > 0.05). For the colour discrimination thresholds, the ML41 and 511 filters showed statistically significant different values compared to the other two conditions for most of the vectors. The filter 511 had the highest impact on the colour vision, as the results resemble to a Tritan defect.Conclusions: The accommodative response in healthy young adults was not significantly different than the no filter condition. The colour discrimination thresholds with the filter ML41 and 511 were significantly different compared to the no filter condition.

Investigation and reduction of finite width effect of coupling beam in bandwidth estimation of coupled MEMS resonator

AbstractBand pass filters are realized by coupled microelectromechanical resonators and their bandwidth is determined by the ratio of coupling beam stiffness to resonator beam stiffness at the coupling location. The coupling beam is connected to the resonator beam in such a way that the resonator beam length and coupling beam width are in the same axis. Practically, it is not possible for the coupling beam to make contact with the resonator beam at a single point. But presently, coupled resonators are designed for specific bandwidth by considering resonator beam stiffness at any point within the contact area between the coupling beam and resonator beam. Due to the finite width of the coupling beam, resonator stiffness at the coupling location is multivalued. It causes additional velocity coupling. So, the bandwidth calculated using single‐point stiffness on the resonator beam will be far from the bandwidth of the actually coupled resonator. For the first time, this finite‐width effect is taken into account. The novelty of this work is the consideration of this finite width effect of coupling beam and cancellation of additional velocity coupling to minimize error in bandwidth estimation. This is achieved by a combination of λ/4 and 3λ/4 coupling beams. In this work, the coupled resonator is modeled using an electrical equivalent circuit.

Electronically tunable positive and negative fractional order inductor circuit using single topology

This article presents electronically tunable grounded and floating fractional order inductor circuits. The proposed circuits employ two operational transconductance amplifiers (OTAs), one fractional order capacitor, one inverter and four MOS switches and are capable to work in positive mode and negative mode without change in topology. The behaviour of the proposed circuit is also analyzed in presence of parasites that may appear in the practical circuit. The functional verification is done via pre and post layout simulations at 90 nm CMOS technology parameter. The usefulness of the proposed positive fractional inductor circuit is demonstrated through fractional order band pass filter and fractional order high pass ladder filter. The performance of the proposed negative fractional inductance circuit is demonstrated through a fractional inductance cancellation circuit.

Investigations on Complementary Split Ring Resonator (CSRR) array integrated printed conformal band pass filters for modern wireless communication applications

This paper presents the performance analysis of two different conformal band pass filters (BPFs) loaded with an array of circular complementary split ring resonators (CSRRs). Type-1 bandpass filter has been designed by integrating a 9 × 9 array of circular complementary split ring resonator on the bottom layer of the filter. Similarly, Type-2 bandpass filter has been constructed by loading an array of 5 × 5 split ring resonator on the patch layer of the filter. A comparative study between Type-1 and Type-2 bandpass filters are also evaluated that shows dual pass bands for Type-1 filter and triple pass bands for the Type-2 bandpass filter. Furthermore, the conformality of both bandpass filters are judged through bending deformation analysis with various bending positions at 15°, 30°, 45°, 60° and 90°. During the bending performance analysis, the suggested BPFs retains the dual and triple pass band characteristics without any major deviations in its characteristic's parameters. Various performance parameters like return loss, insertion loss, group delay, bandwidth, and quality factor are measured. Detailed analysis of E and H field distributions and surface current distributions are also presented. The Type-2 bandpass filter shows better performance in terms of filter properties compared to Type-1 band pass filter. Hence, the prototype of Type-2 filter with an area of 30 × 30 mm2 is fabricated and measured. The validated results are agreed with the simulated results which confirms the applicability of the proposed filter for several modern wireless communication applications such as Wi-Max and personal communication systems (PCS) applications.