Multilayer Filters Research Articles

Reconfigurable multilayer dual-mode bandpass filter based on memristive switch

A novel memristor-based multilayer dual-mode resonator is presented, which is suitable for the design of reconfigurable multi-band filters. The memristor is used as an RF/microwave switch. A dual-band bandpass filter is realized with the proposed memristor-based dual-mode resonators. The corresponding memristor setup circuitry is optimized in order to minimize the circuitry influence on the desired filter frequency response.

Impact of Wavelength Shift in Relative Spectral Response at High Angles of Incidence in Landsat-8 Operational Land Imager and Future Landsat Design Concepts

The Landsat program plays an important role in providing continuous long-term multispectral moderate resolution observations of the earth’s surface. There is an interest by the community to improve the temporal sampling in future generations of the sensors. One way to achieve higher sampling is to collect imagery with a wider swath. For future instruments using multilayer dielectric filters for band selection, this has the further implication that light may enter the filters on the detectors at a higher angle of incidence, which will shift the center wavelength of the spectral bandpasses. Through simulation of a forest environment this paper explored the impact of this effect on measured spectral radiance and the normalized vegetation difference index. The effect is quantified both for angles of incidence seen in the current Landsat-8 Operational Land Imager as well as for pushbroom designs with up to 13° off-axis imaging. Results indicate the effect will be significant compared to instrument noise and comparable to the limit of current requirements on filter manufacturing tolerances.

Multi-Layer Filters: Adsorption and Filtration Mechanisms for Improved Separation.

Filters made of cellulose fiber and perlite particles were prepared using a wet laying papermaking technique. Polyamide-amine-epichlorohydrin (PAE) was added to provide wet strength. Filters were prepared at two different total basis weights of 200 and 400 grams per square meter (gsm). Single and multi-layered filters were structured for each total basis weights. The effect of total basis weights and multi-layered structure on methylene blue adsorption and silicon dioxide (SiO2) particle filtration was investigated. Methylene blue adsorption was performed in two modes: constant pressure and constant flow rate. In both operation modes, the adsorption capacity of multi-layered filters was significantly higher (16–100%) than for single-layer filters at the same overall weight. The effect of layer separation was also characterized using polypropylene separators and tested under constant flow rate operation. Separators provided more effective methylene blue adsorption by generating a well-distributed flow. Filtration performance was quantified with 0.5 μm silicon dioxide particles under constant pressure conditions; this is to mimic bacteria rejection. Filtration capability of SiO2 particles was reduced slightly (12%) with decreasing individual filter layer thickness regardless of the multi-layered structure. Filtering polyethylene glycol (PEG) molecules with two different molecular weights was performed; however, no rejection was recorded. The filter internal pore structure was visualized by 3D-X ray computed tomography and the void fraction was quantified. 400 gsm single layer presented areas of low fiber density forming pores, while the pore volume decreased for thinner filter layers.

Thermal vacuum regolith environment simulator for China’s deep lunar drilling exploration

A thermal vacuum regolith environment simulator for China’s deep lunar drilling exploration was proposed and developed. The simulator can be used to provide not only a vacuum but also a high or low temperature environment for the lunar regolith simulant to a maximum depth of 2 m. It consisted of a vacuum system for simulating an airless condition, a regolith preparation system for compacting the regolith simulant with different bulking densities, and a thermal system for simulating the lunar regolith temperature distribution. Multi-layer stainless steel filters were used to filter regolith particles during the evacuation process. This method accelerated the dissipation of inner gas molecules and maintained the regolith simulant bulk density. The thermal system used iodine-tungsten lamps to heat the surface regolith and silicon oil to refrigerate the subsurface regolith. A rotating and locking mechanism inside the simulation chamber was proposed for multiple drillings within a single environment simulation.

A Survey on Duplicate Data Filtering Methods in Big Data

Big Data analytics is the process of collecting heterogeneous huge sets of data for analyzing .The data are fetched from different sources and can be in heterogeneous form. Data arriving in the big data system will be in giga-bytes for every second. Since, the data are in huge volume, there is a possibility of redundant data that affect the network performance. This article presents the review of different filtering methods and algorithms that are used for duplicate elimination such as Bloom filter, Stable Bloom Filter, multi-layer bloom filter, Counting Bloom Filter with some disadvantages such as false positive and false negative. The aim of this paper is to propose an algorithm for eliminating the duplicate Data in a large data set by using big data analytics.

Crystalline silicon photovoltaic cells used for power transmission from solar-pumped lasers: I. Light trapping concepts

We have proposed a light trapping concept for crystalline silicon photovoltaic (PV) cells used for power transmission from solar-pumped lasers (SPLs) emitting at 1064 nm. The underlying mechanism is multiple reflection between a multilayered angle-selective filter on the front surface and a diffuse reflector on the rear surface of the cell. For the stationary use and optical fiber connection of the SPL-PV combination in which the incident angles of the laser light to the PV cells (ϕ) change within 5–10°, double-cavity bandpass filters realize the required angle selection function. When the SPLs illuminate moving electric vehicles equipped with the PV cells at larger ϕ values, shortpass filters are appropriate. These specially designed angle-selective filters provide significant light trapping performance and consequently absorbances higher than the Yablonovitch limit up to ϕ = 45°. The fact that the present light trapping configuration requires no microfabrication processes is also a great advantage over two- and three-dimensional photonic crystal structures.

Crystalline silicon photovoltaic cells used for power transmission from solar-pumped lasers: II. Practical implementations

We have designed crystalline silicon photovoltaic (PV) cells used for power transmission from solar-pumped lasers (SPLs) emitting at 1064 nm. The practical light-trapping performance of the combination of a multilayered angle-selective filter on the front surface and a diffuse reflector on the rear surface was evaluated by ray-trace simulation, which was taken into account in device simulation. When the SPLs illuminate stationary PV cells or are connected using optical fibers and hence the incident angles to the PV cells are within 10°, a high laser-to-electricity conversion efficiency of around 50% would be feasible under 100 W/cm2 laser illumination using the 50-µm-thick cells. For power transmission to moving objects such as electric vehicles, in which the incident angles change up to 30°, the efficiency of the 75-µm-thick cells is slightly lower because of the less significant light-trapping effect. To realize these high efficiencies, reduction of contact resistance and surface recombination velocity is required.

Design and Fabrication of a Narrow Bandpass Filter with Low Dependence on Angle of Incidence

A multilayer narrow bandpass filter that consists of silver and silicon thin films is designed using the admittance tracing method. Owing to the low loss of silicon in the infrared range, the peak transmittance at a wavelength of 950 nm exceeds 85%. To eliminate the sidebands that are adjacent to the passband, a compact four-layered structure is proposed to generate an angle-insensitive spectrum. In fabrication, a silver-silicon multilayer is deposited to approach the design.

A computational tool to detect DNA alterations tailored to formalin-fixed paraffin-embedded samples in cancer clinical sequencing

Advanced cancer genomics technologies are now being employed in clinical sequencing, where next-generation sequencers are used to simultaneously identify multiple types of DNA alterations for prescription of molecularly targeted drugs. However, no computational tool is available to accurately detect DNA alterations in formalin-fixed paraffin-embedded (FFPE) samples commonly used in hospitals. Here, we developed a computational tool tailored to the detection of single nucleotide variations, indels, fusions, and copy number alterations in FFPE samples. Elaborated multilayer noise filters reduced the inherent noise while maintaining high sensitivity, as evaluated in tumor-unmatched normal samples using orthogonal technologies. This tool, cisCall, should facilitate clinical sequencing in everyday diagnostics. It is available at https://www.ciscall.org.

Ion assisted deposition of Silica-Titania multilayer optical filter for beam steering of Nd:YAG laser

In the present study, a multilayer reflective optical filter consisting of 24 alternate layers of SiO2 and TiO2 was designed and fabricated on BK7 glass substrate using Ion Assisted electron beam Deposition (IAD) technique. The spectroscopic characterization of the filter was carried out in Vis-NIR range with Universal Measurement Accessory (UMA) to measure its optical performance at normal and oblique angles of incidences. The measurements confirmed the optical peak reflectance of more than 99.98% at design wavelength of Nd:YAG laser centred at 1064 nm. The tuning of refractive indices of the constituent layers during deposition resulted in a Full-Width at Half-Maximum (FWHM) bandwidth of 330 nm of the fabricated filter which enables its use at any angle of incidences between 0 and 60° for manipulating the laser beam. Qualitative assessment of the mechanical stability of the coated filter with respect to its adhesion and abrasion resistance was carried out in accordance with MIL-F-48616 and MIL-E−12397 respectively. The achieved optical performance of the coated filter is suited for beam steering and folding of high power laser beams for metal cutting, diamond processing and in other laser based material processing instruments.

Multilayer End Coupled Band Pass Filter using Low-Temperature Co-Fired Ceramic Technology for Broadband Fixed Wireless

This paper presents design approach for realizing multilayer End Coupled Bandpass Filter (ECBPF) using low temperature co-fired ceramic (LTCC) technology at TMRND's LTCC Lab. Design method for the ECBPF is based on the coupled-resonator filter which was realized in LTCC multilayer substrate and operating at the center frequency of 42GHz. Three samples of EC BPF have been designed, simulated, fabricated and investigated in terms of performance and structure size.This multilayer ECBPF were fabricated in the 8 layers LTCC Ferro A6S materials with dielectric constant of 5.8, loss tangent of 0.002 and metallization of gold. The measured insertion loss for ECBPF was 2.43dB and return loss was 22.81dB at the center frequency at 42GHz. The overall size of the fabricated filter was 6.0 mm x 2.5 mm x 0.77 mm.

Composition of Radioactive Aerosols in the Shelter Construction of the Chernobyl Nuclear Power Plant in 2000–2015

The results of the physicochemical studies of radioactive aerosols inside and outside the Shelter construction at the Arch construction stage of the Chernobyl Nuclear Power Plant (ChNPP) in 2000–2015 were presented. The dominant isotopes were shown to be cesium, strontium, americium, plutonium, and uranium. They are carried by disperse particles of 2–7 μm. In subreactor rooms, in particular, 012/7, the composition of aerosols is affected by the erosion of the fuel-containing mass formed in 1986. Submicron cesium carrier aerosols appear as a result of evaporation and condensation during fires and welding works. Radiocesium is a well-soluble component of aerosols, while plutonium isotopes are not readily soluble components. In several rooms, the contents of radon, thoron, and their daughter products exceeded the permissible values. In April–June 2011, the intake of radionuclides from the accident at the Japanese Fukushima-1 NPP, which had AMAD of ~0.5 μm, was detected and tracked using Petryanov multilayer filters. The productivity of filtration units under the dusty conditions in the exclusion zone of ChNPP and in fogs and haze was investigated. Hydrophilic prefilters with 7–10 μm fibers were recommended.

A mesoscale model for the relationship between efficiency and internal liquid distribution of droplet mist filters

Building on work by Kampa et al. (2014) about the liquid distribution in multi-layer oil mist filters, a mesoscale empirical model is proposed for their efficiency. It decomposes the total penetration into a product of independent ‘building blocks’ that are aligned with the mesoscale liquid distribution in steady state, essentially in the form of an oil film and a channel region. The film (typically one very thin region per sandwich) is associated with a film penetration Pfilm and the channel region (consisting typically of multiple layers) with a channel penetration Pchannel. The first layer of wettable media also represents a separate contribution P1st layer.A method is described to derive these unit penetrations from a set of measurements. Experiments are then carried out with filters composed of conventional glass microfiber media, both wettable and non-wettable to compressor oil, in which the fractional penetration of the entire sandwich was measured by SMPS between about 30 and 700 nm. It is shown that the film penetration is substantially reduced for particles above about 100 nm in comparison to that of the dry media due to enhanced inertial deposition, while the channel penetration is generally higher across the board, probably because of a loss of active fiber in the partially saturated media. The last part of the paper is dedicated to practical consequences of this efficiency model.It is shown that the fractional efficiency for an arbitrary number of (identical) layers can be predicted quite accurately from the unit penetrations. Additional measurements of the total downstream concentration as a function of time are used to discuss and explain changes from start-up until steady state.

Activated carbon fiber filters could reduce the risk of surgical smoke exposure during laparoscopic surgery: application of volatile organic compounds.

Generation of smoke is inevitable during surgical procedures. Some volatile organic compounds (VOCs) in surgical smoke are known to be strong carcinogens. We used a prototype of a multi-layered complex filter in an attempt to eliminate VOCs. From June 2015 to July 2015, 20 patients underwent transperitoneal laparoscopic nephrectomy for renal cell carcinoma. Smoke (pre-filter) was collected 20min after the electrocautery device was first used during the surgery, by the direct collection method, with a 5-L Tedlar® gas-sampling bag. Twenty and 120min after the filter was applied, smoke (post-filter) was again collected using the same method. The sample was analyzed by gas chromatography and mass spectrography. The cancer risk and hazard quotient were analyzed based on US Environmental Protection Agency guidelines. Twenty patients with a median age of 54.5 (30-80) years were enrolled in the study. Eighteen VOCs were detected using the Japanese indoor air standards mix analysis. The total elimination rate of the VOCs was 86.49 ± 2.83%. The post-filter (120min) cancer risk (mean ± standard deviation) reduced to a negligible level for benzene, ethylbenzene, and styrene except 1,2-dichloroethane. The post-filter (120min) hazard quotient for each compound decreased to levels posing a negligible risk for acetone, hexane, benzene, toluene, p-xylene, o-xylene, and styrene. Strong carcinogens, such as 1,2-dichloroethane, benzene, and ethylbenzene, were eliminated by more than 85% by using this activated carbon fiber filter and the risks from these compounds decreased to an almost negligible level. We suggest using every measure, including these filters, to protect the health of operating room personnel.

Tannery Wastewater Treatment Using Low Cost Coagulants with Simple Coagulation-Filtration Process

Tannery is the oldest industries in the world. It is characterized as pollutants generating industries, which produce wide varieties of high strength toxic residues. This study has been focused on the removal of physicochemical parameters of tannery wastewater through simple coagulation-filtration techniques using low cost coagulants. Standard methods were used for sampling and analysis. Removal efficiency was measured in terms of reduction of COD, BOD5, suspended solids (SS), total dissolved solids (TDS), conductivity and color. Several doses of coagulants e.g. alum, ferric chloride and their combination were used in treatment process. Maximum removal efficiency was obtained with the combination of alum and ferric chloride dosing at 75 mg/L in terms of color, BOD5, COD, TDS, SS and conductivity corresponding to 75%, 78%, 76%, 37%, 94% and 41% respectively and that were increased to92%, 82%, 80%, 48%, 98% and 51% respectively after sand-stone filtration. Ferric chloride and combination of alum and ferric chloride are recommended for the effective primary treatment of tannery wastewater. The filtration with multi-layer sand-stone filter was effective in removing of color, TDS, conductivity and SS.

An Extended Filtered Channel Framework for Pedestrian Detection

Pedestrian detection is an important example of object detection and has attracted much attention. Many works have shown that good image features provide high detection accuracy, and a few works have investigated enhancing low-level features (e.g., gradient and color features) using a filtered layer (i.e., convolutional layer) to obtain enhanced features or filtered channel features. To investigate whether these features are saturated, this paper adopts the concept of filtered channel features and strengthens them by adding more convolutional layers. Acting as convolution kernels, multilayer filters are applied to low-level features to obtain the extended filtered channel features, providing a powerful feature extractor with multilayer transformation for pedestrian detection. The proposed extended filtered channel framework (ExtFCF) achieves competitive performance on widely used benchmark datasets (Caltech, INRIA, and KITTI datasets), using only histogram of oriented gradient (HOG) and CIE-LUV [a color space composing of luminance (L) and two chrominance (UV) components by International Commission on Illumination] color features (HOG+LUV) as low-level features. One representative ExtFCF implementation achieves the best result compared with the current best traditional pedestrian detection methods on the Caltech dataset.

71‐3: A New Solution without Quantum Dots for LCD to Achieve More Than 90% BT.2020

In this paper , by using the side‐emitting LED backlight with collimating lens and multilayer optical thin film color filter the LCD were successfully developed with Rosh‐compliant and to achieved more than 90% BT.2020 color gamut .The LED light source can use YAG phosphor or normal nitride RG phosphor without using quantum dots solution.

Optical characterization of pore filling in mesoporous multilayers by ultrathin atomic layer deposited hafnium dioxide

An optical technique for the characterization of pore filling in mesoporous silicon (Si) layers is presented. The technique is applied to analyze pore filling by ultrathin hafnium dioxide (HfO2) fabricated by thermal atomic layer deposition (ALD). This technique uses mesoporous multilayers generated by electrochemical etching of crystalline Si to form rugate filters with small bandwidth of the corresponding reflectance spectra. The pore filling and penetration depth into the porous material of the ultrathin hafnium dioxide ALD layers are derived from the measured spectral peak shift of the filter characteristic by using an effective medium approximation. Optical modeling of the multilayer filters was used to simulate the influence of the penetration depth of the ultrathin hafnium dioxide layer into the mesoporous Si on the spectral peak shift. Simulation results show that oxidation of porous Si causes blue shift, whereas pore filling with HfO2 causes red shift of the used rugate filters spectra. These spectral shifts are a result of the corresponding refractive index change of the individual mesoporous layers. Experimental results comparing freshly prepared rugate filters with those coated by thermal ALD show that the blue shift of the peak and thus the transformation of the pores' surfaces by oxidation is dominant for the first few ALD process cycles and that surface oxidation is completed after approximately eight ALD cycles. A red shift of spectral peak position, an indicator of an effective HfO2 coating of the mesopores, started to occur after eight cycles. Further ALD cycles increase the red shift continuously up to saturation, where further ALD will not change the optical spectra of the rugate filters any more. This saturation is related to complete pore sealing of the smallest pores. Pore size distribution and saturation of pore coating thicknesses are compared to evaluate the pore filling. The results obtained with ALD HfO2 in mesoporous Si with pore diameter in the range of 4–8 nm demonstrate that the proposed optical characterization method is sensitive enough to study ALD steps in mesoporous materials.

Design of wideband LTCCBPF with notch band exploiting one‐third isosceles triangular resonator

AbstractThe design of a novel multilayer wideband bandpass filter with one notch band is presented in this letter. The proposed filter structure is composed of one‐third isosceles triangular substrate integrated waveguide (SIW) cavities and the coupled striplines. The SIW cavities structure generates multiple resonant modes which are used to realize the wideband bandpass filter. Owing to the low temperature co‐fired ceramic technology, the stripline and the SIW cavity are printed on multilayer ceramic, which makes the filter compact. The filter have a compact volume of 6.0 × 8.0 × 0.4 mm3. The measured results exhibit the bandpass filter achieves a center frequency of 15 GHz with a 3 dB fractional bandwidth of 33.33% and more than 15 dB attenuation at skirt band. The width of the notch band was about 600 MHz centered at 15.5 GHz. The measured results of fabricated filter are in close agreement with the simulated ones.

High-performance silver-dielectric interference filters for RGBIR imaging.

New architectures of interference silver-dielectric multilayer filters inspired from induced transmission designs are investigated with the prospect of high-performance red-green-blue (RGB) complementary metal oxide semiconductor imaging. The optimized designs provide combined colorimetric, signal-to-noise ratio and sensitivity performances similar to the traditional organic color filters, but without the equirement of an external infrared (IR)-cut filter, which enables the integration of additional channels such as white or IR, in addition to RGB. Due to the sub-micrometer thickness of the stacks, this is a unique solution for fully integrated, high-performance multispectral filters patterned in very small pixels. The concept is demonstrated by a wafer-scale prototype with RGBIR filters patterned down to 1.4μm adjacent pixels with up to 80% transmission.