Rectification Scheme Research Articles

Quality Diagnosis for Rocket Body Structure Manufacturing Process Based on Product Quality DNA

ABSTRACTIn the current multivariety and small‐batch production mode, it is difficult to fully reflect the evolution law of the sampling population due to incomplete sample information in the manufacturing of the rocket body structure. By referring to the principle of biological DNA, a knowledge‐based quality diagnosis strategy is adopted, and a quality diagnosis method for the rocket body structure manufacturing process based on product quality DNA is proposed in this paper. The accumulated experience or knowledge in the past is stored in the product quality DNA knowledge base in the form of cases. Through knowledge retrieval, historical cases with the highest similarity to the product quality DNA to be diagnosed are found, and reasonable control and rectification schemes are provided for the quality problems in the production process, so as to avoid the same quality problems in the future. The feasibility of the method is verified by two case studies of two welds. The results show that the method can effectively and accurately diagnose weld quality.

Correction effect of jet-grouting on high-speed railway subgrade lateral deformation

Viable remediation of the large lateral deformation of high-speed railway (HSR) subgrades, especially in soft soil areas, is still absent. An integrated rectification scheme of high-pressure jet-grouting (HPJG) combined with stress-release techniques was conducted to rectify the large lateral deformation of an operational HSR subgrade in the soft soil area of China, but without any refined design and mechanical analysis before rectification due to the emergency. The objective of the study is to post-evaluate the rectification effects utilising field monitoring data and numerical calculations. The monitoring data showed that the maximum lateral deviation of the subgrade was 69.1 mm, which almost met the expected correction requirements. However, the influence of the excess pore water pressure (EPWP) dissipation on the correction deviation was not considered in the scheme. Therefore, a numerical model was established to further investigate this effect and corresponding mitigation methods. The calculated results revealed that EPWP in the foundation dissipated mostly within 6 months after rectification, and the deformation loss accounted for 30.7% of the total deviation. Prolonging the interval of two-row pile construction can be a plausible approach to mitigate the deviation loss. The findings provide a feasible method for correcting large lateral deformation of HSR subgrades.

High-Performance Light Emitting Diode Lighting Circuits and Their Interior Design Applications

This study explores the application of the half-bridge Inductor-Inductor-Capacitor (LLC) resonant converter in Light Emitting Diode (LED) lighting driver power supplies, with a specific focus on improving efficiency and dimming capabilities. The investigation begins with an analysis of the sliding mode control (SMC) method, utilizing a constant-current design with a fixed switching frequency (FWF). A novel fuzzy frequency-selective SMC dimming strategy is proposed to recognize the challenge of significant output voltage ripple during dimming under a FSF. To address the ripple issue during dimming, an electromagnetic filtering circuit is designed, and a zero-voltage turn-on Metal—Oxide—Semiconductor (MOS) tube is introduced, incorporating a synchronous rectification scheme to mitigate losses in the secondary-side rectification diode. The study comprehensively considers a current-mode self-driven method, specifically tailored to the LLC circuit’s different operating modes. The LLC resonant circuit, along with the subsequent synchronous rectification circuit, is meticulously designed for a 252 W LED driver power supply prototype. A closed-loop simulation circuit model is developed using PSIM software in experimental validation. The feasibility of SMC based on a FSF is affirmed through a comparative analysis of SMC signal waveforms, steady-state output current (OC) models, and resonant tank current waveforms. The investigation into the OC under various SMC conditions demonstrates the half-bridge LLC resonant converter’s ability to achieve stable output with minimal ripple. The designed LED lighting circuit is applied to indoor design, providing adjustable LED brightness and switch status at different power levels. Although obstacles slightly impact the communication quality of the circuit, it remains suitable for the majority of users’ needs.

Geometrical State-Plane-based Synchronous Rectification Scheme for LLC Converter in EVs

Geometrical State-Plane-based Synchronous Rectification Scheme for <i>LLC</i> Converter in EVs

Numerical Study on the Influence of Combined Rectification Facilities on the Flow in the Forebay of Pumping Station

The flow pattern of the forebay of the pumping station has a considerable effect on the operating efficiency and stability of the pump unit. A good forebay flow pattern can enable the pump unit to improve efficiency and operating conditions. This study takes a large pumping station as the research object and considers two rectification schemes, namely, a single bottom sill and a “bottom sill + diversion pier”. Without rectification facilities under different start-up schemes, the forebay flow pattern after the addition of rectification facilities is calculated, and the influence of single and combined rectification facilities is analyzed. Results show large-scale undesirable flow structures such as backflow and vortex in the forebay of the original design that without rectification facilities and uneven flow distribution occurs in the operating unit. The addition of a bottom sill in the forebay can control the central water beam from the water diversion pipe. The flow is divided to spread to both sides of the forebay and can be rectified twice after installing the diversion piers. The combined rectifier facility of “bottom sill + diversion pier” is beneficial to disperse incoming flow and make the flow distribution of each unit more uniform. The backflow and vortex inside the forepond are basically eliminated, and the flow state of the forepond is significantly improved.

Fundamental impedance-based digital synchronous rectification scheme for bidirectional CLLC resonant converters

Fundamental impedance-based digital synchronous rectification scheme for bidirectional CLLC resonant converters

An Improvement of the Cherenkov THz Generation Scheme Using Convex Silicon Prism-Lens Adapters

The terahertz (THz) generation efficiency in the Cherenkov optical rectification scheme can be improved significantly if the silicon adaptor, mounted at the lateral surface of a nonlinear crystal, has a convex output surface with proper geometry. We demonstrate and compare with the results of direct experiments a method for theoretically modeling the angular distributions of the spectral power of THz radiation in the case of different Si adaptors, constructed by mounting plano-spherical lenses on a conventional flat Si prism. The applied method of theoretical modeling shows its usefulness in choosing the best Si adapter geometry.

A Novel Synchronous Rectification Scheme With Low Computational Burden for LLC Resonant Converter in EV Charger Applications

In EV charger applications, high voltage level and high computational burden caused by multiple charging modes bring serious challenges to the synchronous rectification (SR) of LLC resonant converter. Conventional SR schemes can be classified as current sensing-based, voltage sensing-based and sensorless, which are limited by high cost of current sensing, difficulty of high voltage sensing, narrow operating range or high computational burden, respectively. To deal with these problems, this paper proposes a novel SR scheme for LLC resonant converter in EV charger applications. In this scheme, SR control signals are tuned only by main control signal, output voltage and output current, which are naturally available from main controller in EV charger. To this end, no additional signal sensing is required and the cost for SR is reduced. Moreover, the SR tuning principle is on the basis of Kirchhoff's law and phase relationship between main control signal and secondary-side current, which no longer needs to calculate complicated models. Meanwhile, the foresaid tuning process of SR control signals can be implemented by analog circuits. With these effects, this scheme can tune SR control signals effectively over a wide operating range with low computational burden. Furthermore, a virtual current injection strategy is designed to suppress the inversion current of synchronous rectifier. It can guarantee no inversion current and low body diode conduction (BDC) loss. A 600-V input 200 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\sim$</tex-math></inline-formula> 300-V output LLC prototype converter is built to verify the proposed SR scheme.

A Disturbance Observer-based Novel Fuzzy SMC Control Scheme for Path Tracking of AUV with Mismatched Disturbances

A new sliding mode control scheme is proposed for the path tracking problem of autonomous underwater vehicles (AUVs) with uncertainty and mismatch interference. Considering the complexity of parameter rectification, a fuzzy logic controller-based system rectification scheme is designed in this paper. In the control system, a disturbance observer (DOB) and a radial basis function neural network (RBFNN) are used to estimate the mismatch disturbance and uncertainty, respectively. In addition, this paper analyzes the conditions for the Liapunov stability of the designed controller and the results show the closed-loop stability of the control system. The control scheme can be applied to the path tracking of underwater robots with rapidly changing trajectories in different driving environments. Finally, a number of comparative experiments are carried out to demonstrate the good performance of the proposed controller.

POWER STATIC CONVERTER OF TRACTION ELECTRIC DRIVE OF AC ELECTRIC TRAINS

Purpose. Increasing the operational indicators of suburban transportation on railways electrified by alternating current due to the modernization of traction static converters of ER9M electric trains. Methodology. The methodological basis of the study is the general theoretical provisions and principles of the system approach of theoretical electrical engineering, the theory of power converters. The main principles of construction of traction static converters of electric rolling stock of railways are used. Findings. The analysis of the basic rectification schemes of alternating current electric trains was performed. As an alternative scheme, it is proposed to introduce a controlled rectification scheme based on a four-zone rectification scheme, which is similar to electric locomotives, which allows using most of the known advantages of non-contact traction electric drive control systems. Some energy figures are calculated for the fully controlled and semi-controlled circuit. As a result of the comparison, the modernization option based on a semi-controlled rectification scheme was selected. The required values of starting power of the transformer and power factors for schemes with uncontrolled, fully controlled and semi-controlled rectifiers are determined. A selection of modern semiconductor elements is offered for the configuration of converters. It was shown that in the case of modernization of the rectifier scheme, there is no need for significant capital investments due to the preservation of the main traction transformer and traction motors of the electric train. Practical value. The obtained results can be used by enterprises that carry out major repairs of alternating current electric trains.

Universal Synchronous Rectification Scheme for LLC Resonant Converter Using Primary-Side Inductor Voltage

In recent years, many advanced modulation strategies have been applied in LLC resonant converters, resulting in the increased demand for the synchronous rectification (SR) schemes without modulation strategy limitation. However, the conventional universal SR schemes are mainly on the basis of primary/secondary side current or drain-source voltage of synchronous rectifiers, which are limited by high cost of current transformer (CT) and loss of duty cycle caused by parasitic inductance, respectively. To deal with these problems, this paper proposes a novel SR scheme for LLC resonant converter. Firstly, a SR analysis method on the basis of the idea of power transmission is proposed. It can decouple SR from modulation strategy. Based on this method, this paper proposes a universal SR scheme using primary-side inductor voltage. The scheme is no longer restricted by the modulation strategy of converter. Meanwhile, no CT is required, thereby reducing the cost and conduction loss. Thanks to the large signal sensing-based, this scheme has good noise immunity. Moreover, it eliminates the negative effect of parasitic inductance by integral operation. With these effects, it has high accuracy of SR. Furthermore, an easily-debugged analog implementation is designed, which only needs to adjust one component parameter. Finally, experimental results show that the proposed scheme is compatible with different modulation strategies, and it has higher efficiency than the commercial SR scheme in a wide range of operating conditions.

Virtual trial assembly of large steel members with bolted connections based on point cloud data

Virtual trial assembly (VTA), an alternative to physical trial assembly, has been used in many projects owing to its advantages of low time consumption and low cost. However, the existing methods based on the terrestrial laser scanner (TLS) have low precision, are inefficient, and cannot guide rectification, making them impractical for large steel members with bolted connections. Therefore, this study introduces an automated approach to perform VTA using 3D laser scanning technology and building information modeling (BIM). In particular, a multi-scale data acquisition scheme that integrates a TLS and hand-held scanner is proposed to collect high accuracy point cloud data (PCD). Moreover, a rectification scheme based on particle swarm optimization is developed for gusset plates to guide rectification, and two efficient registration methods are established to align the scanned PCD with BIM model. The accuracy and feasibility of the proposed method are demonstrated through application to an actual suspension bridge.

Deep Learning-Based Improved WCM Technique for Soil Moisture Retrieval with Satellite Images

The water cycle around the globe is significantly impacted by the moisture in the soil. However, finding a quick and practical model to cope with the enormous amount of data is a difficult issue for remote sensing practitioners. The traditional methods of measuring soil moisture are inefficient at large sizes, which can be replaced by remote sensing techniques for obtaining soil moisture. While determining the soil moisture, the low return frequency of satellites and the lack of images pose a severe challenge to the current remote sensing techniques. Therefore, this paper suggested a novel technique for Soil Moisture Retrieval. In the initial phase, image acquisition is made. Then, VI indexes (NDVI, GLAI, Green NDVI (GNDVI), and WDRVI features) are derived. Further, an improved Water Cloud Model (WCM) is deployed as a vegetation impact rectification scheme. Finally, soil moisture retrieval is determined by the hybrid model combining Deep Max Out Network (DMN) and Bidirectional Gated Recurrent Unit (Bi-GRU) schemes, whose outputs are then passed on to enhanced score level fusion that offers final results. According to the results, the RMSE of the Hybrid Classifier (Bi-GRU and DMN) method was lower (0.9565) than the RMSE of the Hybrid Classifier methods. The ME values of the HC (Bi-GRU and DMN) were also lower (0.728697) than those of the HC methods without the vegetation index, the HC methods without the presence of water clouds, and the HC methods with traditional water clouds. In comparison to HC (Bi-GRU and DMN), the HC method without vegetation index has a lower error of 0.8219 than the HC method with standard water cloud and the HC method without water cloud.

Fully automatic DOM generation method based on optical flow field dense image matching

ABSTRACT Automatic Digital Orthophoto Map (DOM) generation plays an important role in many downstream works such as land use and cover detection, urban planning, and disaster assessment. Existing DOM generation methods can generate promising results but always need ground object filtered DEM generation before otho-rectification; this can consume much time and produce building facade contained results. To address this problem, a pixel-by-pixel digital differential rectification-based automatic DOM generation method is proposed in this paper. Firstly, 3D point clouds with texture are generated by dense image matching based on an optical flow field for a stereo pair of images, respectively. Then, the grayscale of the digital differential rectification image is extracted directly from the point clouds element by element according to the nearest neighbor method for matched points. Subsequently, the elevation is repaired grid-by-grid using the multi-layer Locally Refined B-spline (LR-B) interpolation method with triangular mesh constraint for the point clouds void area, and the grayscale is obtained by the indirect scheme of digital differential rectification to generate the pixel-by-pixel digital differentially rectified image of a single image slice. Finally, a seamline network is automatically searched using a disparity map optimization algorithm, and DOM is smartly mosaicked. The qualitative and quantitative experimental results on three datasets were produced and evaluated, which confirmed the feasibility of the proposed method, and the DOM accuracy can reach 1 Ground Sample Distance (GSD) level. The comparison experiment with the state-of-the-art commercial softwares showed that the proposed method generated DOM has a better visual effect on building boundaries and roof completeness with comparable accuracy and computational efficiency.

Двенадцатипульсовые выпрямители в системе электроснабжения городского электрического транспорта

The introduction of twelve-pulse rectifiers instead of six-pulse ones at traction substations of urban electric transport leads to an increase in technical and economic indicators, energy savings, a decrease in leakage current. These result in electrical safety of passengers, a trolleybus driver and depot maintenance personnel. Twelve-pulse rectifiers can have a serial or parallel connection of sixpulse bridges. With a parallel circuit, it is necessary to have an equalizing reactor. The implementation of a twelvepulse serial type rectification scheme can be carried out by industrial development by manufacturers of new dry converter transformers with different typical power and new rectifiers (blocks). As part of the new rectifiers, it is necessary to have tablet avalanche valves with coolers based on heat pipes due to their advantages over nonavalanche valves.

Deviation rectification of a high-rise building with piled raft foundation: a case study

Deviation rectification of a high-rise building with a piled raft foundation was successfully carried out by vertically digging holes. Through site investigation and finite-element analyses of pile foundation settlement, the building tilt was attributed to shortening of the pile length, large post-construction settlement and cancellation of the setting of the post-cast strip of concrete between the main building and the skirt of an underground garage. A comprehensive rectification scheme was conducted, including drilling settlement-resisting micropiles on the side with a greater subsidence, cutting off the raft between the main building and the garage, vertically digging holes and disturbing soil on the side with less subsidence. When the rectified inclination reached the proposed value, the foundation was strengthened by the micropiles for settlement reduction and bearing capacity enhancement. During construction, close monitoring was carried out to guide dynamically the soil extraction operation and monitor building settlement. By analysing the monitoring data over time, the effectiveness of soil extraction for building rectification was verified, and the rectification mechanism of high-rise buildings supported on piled raft foundations was clarified. Finally, the rectification scheme was evaluated and discussed.

Analysis and improvement of measures for lightning protection of 35kV transmission line in a mountainous area

Lightning is an important factor affecting the safe and reliable operation of power transmission and distribution lines. As most power transmission and distribution lines are built in mountainous areas with complex terrain and changeable weather, the lightning accidents in mountainous areas are much higher than those in plain areas. Firstly, the mechanism of lightning damage and common measures of lightning protection are analyzed. Then, taking Lufeng line in Yunnan province as the object, taking the topographic and geomorphic characteristics of the line, the activity intensity of lightning strike and the line structure into consideration, three measures are compared by increasing the number of insulator string pieces, reducing the grounding resistance of poles and towers, and erecting lightning conductor across the line. Finally, erecting lightning conductor across the line is adopted to rectify the line. The feasibility and practicability of the rectification scheme are proved by calculation.

Exploring mechanical assonance for impact energy harvesting using acoustic metamaterials

Acoustic metamaterials are engineered to possess unique dynamic properties that are not commonly found in nature. It has been demonstrated that customizing the characteristics of their local features can help optimize their dynamic performance under specific loading conditions. Drawing inspiration from the literary device called “assonance,” the term “mechanical assonance” may be ascribed to the dynamic phenomenon realized by sequencing oscillators with tuned responses within a waveguide to engineer a prescribed wave transformation across it. In this context, assonance provides a framework to utilize resonant local features within a host structure or material and interactive mechanisms thereof as building blocks to create enriched functionalities for acoustic metamaterials. Using a discrete element representation for an acoustic metamaterial barrier (AMB), a numerical study is conducted to ascertain parametric dependence for assonant mechanisms related to resonator frequencies, their sequencing, and host material stiffness. Normalized metrics are extracted to estimate transmitted pulse mitigation under impact-type loading. It is found that resonator sets with octave spacing having the number of resonators of a specific frequency proportional to that frequency’s amplitude in the input spectrum is desirable for lower transmissibility. Further, sequencing the lowest frequency resonator set closest to the incident-side gives better performance. Engineering a high degree of impedance mismatch between host material sections is also preferable. The energy sequestered by the local resonators can be harvested utilizing the resonator’s mass as the multifunctional kernel for a linear electromagnetic generator. A multiphysical model is developed to predict the harvested electric voltage and power from the AMB and validated using proof-of-concept experiments. Finally, various coil placement and voltage rectification schemes are also studied using simulations to ascertain preferable design configurations.

DQN-based gradual fisheye image rectification

Fisheye image rectification is a classic and important task in the computer vision area, which is generally treated as a pre-processing step in many application scenarios. Most of the existing fisheye image rectification methods focused mainly on building a direct (one-step) projection relationship between fisheye images and corrected images. Although these methods have achieved impressive performance, they depended heavily on data distribution and cannot work well on images whose distortion parameters are out of range. To address this issue, we propose a multi-step gradual image rectification scheme. In particular, we treat the fisheye image rectification problem as one Markov Decision Process and employ a widely-used deep reinforcement learning method (i.e., Deep Q-Network) to solve the problem. In addition, we build a new large-scale fisheye image dataset to evaluate our method, which contains 50,000 training images and 5000 test images. Experimental results show the proposed method can better handle images with a wide range of distortion.

Fast detection method of transmission line defects and faults based on airborne laser LiDAR

In view of the fact that it is difficult for transmission line operators to find transmission line defects and accurate location information in time, and in the face of the discovered transmission line defects, they are unable to quickly and accurately return detailed defect information to provide urgent repair to provide rectification solutions, etc., this paper proposes a fast transmission line defect fault detection method based on airborne laser LiDAR, and compares and analyzes it by using laser point cloud data in different periods. It is found that there are some defects such as the interruption of the transmission line channel and the sinking of the tower foundation. Using laser point cloud data, the tilt detection and deformation of poles and towers are found, and large-scale topographic maps are quickly generated to quickly restore the three-dimensional channel environment of transmission lines, so as to provide auxiliary decision-making for transmission line defects and fault rectification schemes. The digital and scientific management of transmission line defects and equipment fault detection are realized through laser point cloud.