Filter Technology Research Articles

A 3.7-to-10 GHz Low Phase Noise Wideband LC-VCO Array in 55-nm CMOS Technology

This paper presents a four-core LC-VCO array in 55 nm CMOS technology. Based on the multi-core VCO array technology and the switched capacitor array technology, the tuning range is expanded, and the phase noise optimization in a wide tuning range is achieved based on the second harmonic noise filtering technology and the Q value degeneration technology, as well as the optimization of the capacitor array switching transistors. The proposed VCO array, occupying a chip area of 1.65 × 1.44 mm2, realizes a measured oscillation frequency range of about 3.7−10 GHz with phase noise of −127.5~−116.08 dBc/Hz at 1 MHz frequency offset, and achieves an output power of 2.69 dBm from a total power consumption of 52.8 mW.

Modelling and analysis of the influence of in-plane vertical modes on the internal resonance of cable-stayed bridges

To study the complex mechanism of internal resonance in cable-stayed bridges, an integrated dynamic system comprised of four stay cables and a bridge beam was established in this study. Considering the effect of the beam’s shear force and axial force and by applying the finite difference method, the dynamic equations under non-linear boundary conditions were derived based on the D’Alembert principle and Galerkin method. By comparing the results obtained from the dynamic equations with those obtained by a finite element model (FEM), the linearization and non-linear characteristics of the dynamic model were further verified and discussed. The results of the analytical simulation based on the 4th Runge–Kutta Method show that a severe internal resonance is observed once the ratio of local mode and the undamped in-plane vertical natural mode (IVNM) meets 1:1 or 1:2. The conditions regarding the threshold of the initial excitations are also discussed. For the exceptions, the concept of the zero-point of a mode shape (ZPS), where the correlation coefficient in the vertical mode of a certain order equals zero, was proposed and applied in the analysis of the influence of the IVNMs on internal resonance. It is further illustrated that the cables located at the ZPS are not excited by the IVNM of the corresponding order. Additionally, when the excitations act on the ZPS, the IVNMs of the corresponding order are not initially observed in the structure. By using the filtering technology with a zero-phase-shift, the separated vibration signals further revealed that the IVNM becomes re-excited in the global system and thus the re-excited resonance occurs in the cables under specific conditions: an increase in time and excitation value. Three conditions regarding the modal interaction processes of the re-excited resonance were further investigated and discussed.

Enhanced soot oxidation by oxygen vacancies via K + doped CuFe 2 O 4 spinel catalysts

Soot particulate emitting from diesel engines are serious to both human health and environment. Efficient catalyst is vital in diesel particulate filter technology to decrease soot oxidation temperature. Cu1−xKxFe2O4 (x = 0, 0.05, 0.1, and 0.15) catalysts are synthesized and analyzed with XRD, Raman, BET, SEM, TEM, TG, EDS, XPS, catalytic activity tests, and kinetic analysis. The results suggests that many factors affect the catalytic activity, and the contents of oxygen vacancies are dominant. A large amount of oxygen vacancies which facilitate to the soot oxidation are created with the assistance of K+, and they increase with the increasing doping contents. Excessive surface concentration of K+ may lead to the partially covering of active sites of the catalysts. Therefore, Cu0.9K0.1Fe2O4 catalyst exhibits the best catalytic activity in soot oxidation, which decreases the Tmax of soot by 279°C. This decrease makes it highly promising for application in diesel particulate filter.

Back to the Basics: Inferior Vena Cava Filters.

Inferior vena cava filters are an important therapeutic option for patients with venous thromboembolism and contraindication to anticoagulation. Indications for filter placement have varied over the previous decades. This article discusses the history of inferior vena cava filter use, with a basic overview of technology and specific devices. Finally, this article reviews emerging filter design and technology. Understanding the basics of inferior vena cava filters is critical to building more robust clinical data for the purpose of improving patient outcomes.

Decentralized Event-Triggered Adaptive Fuzzy Control for Nonlinear Switched Large-Scale Systems With Input Delay Via Command-Filtered Backstepping

This article presents a decentralized fuzzy adaptive event-triggered command-filtered control scheme for switched large-scale nonlinear systems with input delay. Fuzzy logic systems are employed to approximate uncertain nonlinearities and a novel observer is constructed to estimate unmeasured states. The “explosion of complexity” defect inherent in the backstepping approach is overcome by employing command filter technology. An auxiliary system is designed to compensate for the effect of input delay, and a novel event-triggered decentralized controller is derived based on the common Lyapunov function method. This article shows that the presented strategy guarantees that all closed-loop variables are semiglobally uniformly ultimately bounded. Finally, simulation results are shown to further confirm the presented strategy’s validity.

Removal of indoor air ozone using carbon-based filters: Systematic development and validation of a predictive model

Exposure to ozone can cause several adverse health effects on human beings. Carbon-based filters are usually used for the removal of ozone from indoor air. The main problem with Carbon-based filters technology is the exhaustion of carbon because of irreversible reactions with ozone. Therefore, the knowledge of the service life of filters is crucial for building engineers and designers. Since testing at low indoor concentrations is time-consuming and expensive, the existing standards suggest experimenting with high concentrations. Thus, predictive models need to be developed to estimate the service life of filters. This work provides a model to estimate the breakthrough curves of three different combined (multi-layer) filters. The model augmented mass transfer equations with a reaction rate model and divided them into interpellet mass transfer and kinetic models. First, the reaction rate parameters were measured by fitting the model onto experimental data of all filters challenged with 9 ppm or 90 ppm of ozone. This was followed by validating the model for lower concentrations. In addition, to show the model validity for real-life application, its prediction was compared with the experimental data collected using the full-scale experimental setup and higher velocity. There was excellent agreement between the model prediction and the experimental results for all filters. Furthermore, an inter-model comparison was performed to determine the importance of different mass transfer steps. The results showed internal diffusion and axial dispersion as rate-limiting steps along with reaction. Finally, a sensitivity analysis was conducted on reaction kinetic parameters, axial dispersion coefficient, external mass transfer coefficient, and activated carbon particle porosity, which indicated negligible effects of external mass transfer and porosity variations.

Research on the Error of Global Positioning System Based on Time Series Analysis.

Due to the poor dynamic positioning precision of the Global Positioning System (GPS), Time Series Analysis (TSA) and Kalman filter technology are used to construct the positioning error of GPS. According to the statistical characteristics of the autocorrelation function and partial autocorrelation function of sample data, the Autoregressive (AR) model which is based on a Kalman filter is determined, and the error model of GPS is combined with a Kalman filter to eliminate the random error in GPS dynamic positioning data. The least square method is used for model parameter estimation and adaptability tests, and the experimental results show that the absolute value of the maximum error of longitude and latitude, the mean square error of longitude and latitude and average absolute error of longitude and latitude are all reduced, and the dynamic positioning precision after correction has been significantly improved.

IMS: The Greatest Show on Earth [President’s Column

This month&#x2019;s <i>IEEE Microwave Magazine</i> is devoted to all things related to the 2022 IEEE Microwave Theory and Technology Society (MTT-S) International Microwave Symposium (IMS). IMS 2022 is the world&#x2019;s foremost gathering for ultrahigh-frequency, RF, wireless, microwave, millimeter-wave, terahertz, and optical frequency technology. It encompasses everything from basic technologies to components to systems, including the latest RF integrated circuits (ICs), microwave ICs, microelectromechanical systems, and filter technologies, as well as advances in CAD, modeling, electromagnetic simulation, and more. The conference includes technical and interactive sessions, exhibits, student competitions, panels, workshops, tutorials, and networking events <xref ref-type="bibr" rid="ref2">[2]</xref>.

Vision Robot Path Control Based on Artificial Intelligence Image Classification and Sustainable Ultrasonic Signal Transformation Technology

The unsupervised algorithm of artificial intelligence (AI), named ART (Adaptive Resonance Theory), is used to first roughly classify an image, that is, after the image is processed by the edge filtering technology, the image window is divided into 25 square areas of 5 rows and 5 columns, and then, according to the location of the edge of the image, it determines whether the robot should go straight (represented by S), turn around (represented by A), stop (T), turn left (represented by L), or turn right (represented by R). Then, after sustainable ultrasonic signal acquisition and transformation into digital signals are completed, the sustainable supervised neural network named SGAFNN (Supervised Gaussian adaptive fuzzy neural network) will perform an optimal path control that can accurately control the traveling speed and turning of the robot to avoid hitting walls or obstacles. Based on the above, this paper proposes the use of the ART operation after image processing to judge the rough direction, followed by the use of the ultrasonic signal to carry out the sustainable development of artificial intelligence and to carry out accurate speed and direction SGAFNN control to avoid obstacles. After simulation and practical evaluations, the proposed method is proved to be feasible and to exhibit good performance.

Development and Application of SAW Filter.

With the in-depth advancement of the fifth generation (5G) mobile communication technology, the technical requirements for filters are also constantly improving. Surface acoustic wave (SAW) filters are widely used in home TV, mobile communications, radio frequency filters and radar due to their simple structure, few mask layers, easy miniaturization, and low cost. Through the continuous improvement of communication technology, SAW has developed into various high-performance acoustic filters from bulk SAW with the support of some new architectures, new materials and advanced modeling techniques. This paper analyzes and reviews the research situation of SAW filter technology.

Luminescence imaging of solar modules in full sunlight using ultranarrow bandpass filters

AbstractPhotovoltaic (PV) electricity generation is the fastest growing energy source globally and also humanity's best opportunity to achieve the urgently required deep decarbonisation of the energy sector. As PV enters the terawatt scale, with millions of modules in a single PV power plant, quality testing of installed PV modules becomes indispensable to guarantee PV as a reliable long‐term source of electricity. We present a method that extends the use of photoluminescence (PL) imaging to field‐deployed solar modules in full sunlight. The method takes advantage of sunlight absorption in the Earth's atmosphere in a narrow spectral range around 1,135‐nm wavelength and recent developments in ultranarrow bandpass optical filter technology. The technical principles and experimental data are provided. This method lays the foundations for PL imaging, a powerful inspection method for the PV industry and research, to be applied to routine high‐volume inspection of fielded PV modules on large‐scale solar power plants.

Product Assortment, Choice Overload, and Filtering Technology across Retail Contexts

ABSTRACT Research regarding consumer choice and assortment size has led to contradictory findings. Extant research demonstrates that consumers prefer large product assortments, as they are more likely to find an item that matches their preferences). On the other hand, research has shown that large choice sets can overwhelm consumers and lead to increased decision difficulty and levels of regret. Experiment 1 examines the moderating effect filtering has on the relationship between assortment size and decision difficulty, decision process satisfaction, and regret. Experiment 2 examines filtering but adds situational involvement as a moderator. Results offer support for the moderating role of filtering and situational involvement in choice overload. The results of this research extend the choice overload literature and have managerial implications for the retail sector, particularly as it relates to omnichannel filtering technologies and product assortments.

Recommendation method for fusion of knowledge graph convolutional network

In the application of internet of vehicles system, it is particularly important to obtain real-time and effective vehicle information and provide personalized functional services for vehicle operation. This algorithm combines knowledge graph technology with convolutional network and presents a new algorithm model, that is, when calculating the representation of a given entity in the knowledge graph, the information of the neighboring entity is combined with the deviation. Through the integration of neighbor entity information, the local neighborhood structure can be better captured and stored in each entity, and the weight of different neighbor entities depends on the relationship between them and the specific user, which can better reflect the user's personalized interests, in order to fully demonstrate the characteristics of the entity. Compared with the traditional coordinated filtering technology SVD model, this model has improved accuracy and F1 value.

Recognition and Error Correction of Piano Playing Features Based on Filtering Technology

The extraction of piano features needs to be based on mature technology, but there is no mature technology for feature recognition of music to ensure the correct rate of feature extraction. This article combines filter processing technology to carry out the research on piano playing feature recognition and builds an intelligent error correction system, and it realizes the feature recognition and error correction of piano playing with the support of filter technology. Moreover, this article conducts experimental research on the system constructed. Through experimental research, it can be seen that the piano performance feature recognition system proposed in this article can effectively recognize the piano practitioner’s playing effect and record it for error correction. This intelligent method can effectively improve the piano playing effect.

Photoelectrochemical oxidation assisted air purifiers; perspective as potential tools to control indoor SARS-CoV-2 Exposure

Coronavirus diseases 2019 (COVID-19), a viral infection pandemic, arises due to easy human-to-human transmission of severe acute respiratory syndrome coronavirus (SARS-CoV-2). The SARS-CoV-2 causes severe respiratory disorders and other life-threatening diseases (during/post-infection) such as black mold disease, diabetes, cardiovascular, and neurological disorders/diseases. COVID-19 infection emerged challenging to control as SARS-CoV-2 transmits through respiratory droplets (> 10 µm size range), aerosols (< 5 µm), airborne, and particulate matter (PM1.0 PM2.5 and PM10.0). SARS-CoV-2 is more infective in indoor premises due to aerodynamics where droplets, aerosols, and PM1.0/2.5/10.0 float for a longer time and distance leading to a higher probability of it entering upper and lower respiratory tracts. To avoid human-to-human transmission, it is essential to trap and destroy SARS-CoV-2 from the air and provide virus-free air that will significantly reduce indoor viral exposure concerns. In this process, an efficient nano-enable photoelectrochemical oxidation (PECO, a destructive approach to neutralize bio-organism) assisted air purification is undoubtedly a good technological choice. This technical perspective explores the role of PECO-assisted Air-Purifiers (i.e., Molekule as a focus example for proof-of-concept) to trap and destroy indoor microorganisms (bacteria and viruses including Coronaviruses), molds, and allergens, and other indoor air pollutants, such as volatile organic compounds (VOCs) and PM1.0/2.5/10.0. It is observed through various standard and non-standard tests that stimuli-responsive nanomaterials coated filter technology traps and destroys microbial particles. Due to technological advancements according to premises requirements and high-performance desired outcomes, Molekule air purifiers, Air Pro Air -Rx, Air Mini, and Air Mini+, have received Food and Drug Administration (FDA) clearance as a Class II medical device for the destruction of bacteria and viruses.

An Environmentally Friendly Technology of Metal Fiber Bag Filter to Purify Dust-Laden Airflow

Over the past decades, China has suffered from negative environmental impacts from distempered dust-laden airflow-purification activities. After a decade of effort, dust-laden airflow purification and powder particle recycling have been realized in specialized companies in China, and law enforcement for illegal activities of dust-laden airflow discharge has also been made increasingly strict. Thus, up to now, dust-laden airflow purification in China should be developed toward being more in-depth and refined to promote industrial applications of dust-laden airflow purification. This article reviews the status of existing technologies for dust-laden airflow purification. A novel and environmentally friendly technology for purifying the dust-laden airflow is proposed which uses a metal bag filter to collect dust particles. The bottlenecks in the dust-laden airflow-purification system are analyzed. Some preliminary experiments of pinch technologies are also conducted. Finally, in order to provide directional guidance for the future development of metal bag filters, some key points regarding the metal bag filter purification system are proposed to point towards a future trend in dust-laden airflow purification.

Trajectory tracking method of natural gas, district heating and power systems

The accurate state trajectory is essential for the optimal control of natural gas, district heating and power systems. However, the measurements experience random errors and bad data inevitably, which may cause undesirable control strategies. Aiming at this problem, a state trajectory tracking method of natural gas, district heating and power systems is proposed. The physical model of natural gas, district heating and power systems coupled by combined heating and power units and gas turbine units is established based on partial differential equations and Holt’s exponential smoothing techniques. To enhance the tracking accuracy, the predicted states by the physical model and measurements are combined by Kalman filter technologies, and a novel tracking method of natural gas, district heating and power systems is proposed. The method is applied on natural gas, district heating and power systems with a 14-pipe heating system, 30-node gas system and IEEE 39-bus system coupled by two combined heating and power units and gas turbine units. The total variances and filter coefficients are used to evaluate the tracking performance. The results indicate that filter coefficients are less than 1, meaning the method has the ability to enhance the tracking accuracy compared with the measurements.

A hybrid of the selected mapping and partial transmit sequence approaches for reducing the high peak average to power ratio based on multi-carrier systems – review

The orthogonal frequency division multiplexing (OFDM)-4G and 5G filter technology suffer a drawback that represents the direction of the peak average to power ratio (PAPR) in orthogonal frequency division multiplexing due to the nonlinear nature of the transmitter. There are a lot of traditional and hybrid methods of these traditional methods to reduce the harmful high PAPR value. Newly, several new hybrid methods have been adopted to reduce PAPR but it faces an increasing level of computational complexity in the system. In this paper, two important and effective conventional methods for reducing PAPR are studied, analyzed, and investigated for the hybrid pathway which is the incorporation of selective mapping (SLM) method and partial transport sequencing (PTS) method, which achieve increased efficiency of PAPR reduction while computing the computational complexity of each method. The method depends and balances with computational complexity. The search is based on multi-carrier connections such as multi carrier-code division multiple access (MC-CDMA) and OFDM.

A hybrid of the selected mapping and partial transmit sequence approaches for reducing the high peak average to power ratio based on multi-carrier systems–review

The orthogonal frequency division multiplexing (OFDM)-4G and 5G filter technology suffer a drawback that represents the direction of the peak average to power ratio (PAPR) in orthogonal frequency division multiplexing due to the nonlinear nature of the transmitter. There are a lot of traditional and hybrid methods of these traditional methods to reduce the harmful high PAPR value. Newly, several new hybrid methods have been adopted to reduce PAPR but it faces an increasing level of computational complexity in the system. In this paper, two important and effective conventional methods for reducing PAPR are studied, analyzed, and investigated for the hybrid pathway which is the incorporation of selective mapping (SLM) method and partial transport sequencing (PTS) method, which achieve increased efficiency of PAPR reduction while computing the computational complexity of each method. The method depends and balances with computational complexity. The search is based on multi-carrier connections such as multi carrier-code division multiple access (MC-CDMA) and OFDM.

Design of Knitted Garment Design Model Based on Mathematical Image Theory

Iconology is an approach used by Western art theorists and art history researchers to explain plastic art and even relative to other various plastic art activities. This article is aimed at researching and discussing the design of knitted garment design model based on mathematical image theory. This article first discusses the application of digital image processing in the field of knitted clothing; digital image processing technology has a wide range of applications in the field of knitted clothing, including four aspects of fiber, yarn, fabric, and clothing, and proposes digital image filtering technology and digital image fuzzy filtering algorithm and then researches and analyzes the drape performance of knitted fabrics. Fabric drape is an important performance that reflects the beauty of the appearance of the fabric. The design of knitted garments is discussed based on mathematical imagery, and finally, the pressure performance of knitted garments is tested and analyzed. The experimental results in this paper show that the data correlation of the clothing pressure measured in different situations of the upper body is 0.87328, 0.779832, and 0.780213, respectively, under the plain weave, rib, and mesh fabric clothing fabrics. It shows that under the pressure of this degree of knitted clothing, it is in line with the needs of human healthy growth, because a certain degree of clothing pressure can maintain human physical and mental health and improve the quality of life.