Real-time Calculation Method Research Articles

Precision encoder grating mounting: a near-sensor computing approach.

The rotary motor plays a pivotal role in various motion execution mechanisms. However, an inherent issue arises during the initial installation of the encoder grating, namely, eccentricity between the centers of the encoder grating and motor shaft. This eccentricity substantially affects the accuracy of motor angle measurements. To address this challenge, we proposed a precision encoder grating mounting system that automates the encoder grating mounting process. The proposed system mainly comprises a near-sensor detector and a push rod. With the use of a near-sensor approach, the detector captures rotating encoder grating images, and the eccentricity is computed in real-time. This approach substantially reduces the time delays in image data transmission, thereby enhancing the speed and accuracy of eccentricity calculation. The major contribution of this article is a method for real-time eccentricity calculation that leverages an edge processor within the detector and an edge-vision baseline detection algorithm. This method enables real-time determination of the eccentricity and eccentricity angle of the encoder grating. Leveraging the obtained eccentricity and eccentricity angle data, the position of the encoder grating can be automatically adjusted by the push rod. In the experimental results, the detector can obtain the eccentricity and eccentricity angle of the encoder grating within 2.8 s. The system efficiently and precisely completes a encoder grating mounting task in average 25.1 s, and the average eccentricity after encoder grating mounting is 3.8 µm.

Research on bearing capacity and stability of deep-water novel combined wellhead based on experimental methods

The combined wellhead has the advantage of high bearing capacity and broad prospects for application in the construction of deep water surface wells; therefore, it is important to conduct relevant research to guide the construction of combined wellheads. The aim of this paper is to study the mechanical characteristics of the combined wellhead in the longitudinal direction and establish the method for real-time calculation of the bearing capacity of the combined wellhead taking into account the effects of installation. The variations of external wall pressure and internal soil pressure during installation and the waiting process of the combined wellhead were investigated by indoor experiments. The installation efficiency of the combined wellhead at different negative pressure conditions was also compared. The experimental results show that the pressure on the outer wall of the combined wellhead facility gradually increases as the depth of the combined wellhead facility increases, and the closer it is to the bottom, the greater the soil pressure. The pressure on the inner soil will increase rapidly during the installation process to almost the same level, while the pressure on the outer soil will increase slightly. During the waiting process of the combined wellhead, as the waiting time increases, the soil damaged during the installation process gradually recovers, and the external wall pressure gradually rises. Moreover, the pressure on the outer wall gradually increases, the pressure on the inner soil decreases slightly leveling off within about 24 h. An appropriate increase in suction pressure facilitates the installation of the combined wellhead, and approximately 2.0 L/min is the optimal option for installation. The computational model developed in this paper and the experimental measurements corroborate each other. These combined wellheads significantly improve the stability of deep water soft-soil well construction and provide a theoretical benchmark for developing oil, gas and hydration in deep water.

Research on Real-Time Calculation Method of Transformer Temperature Field Based on Reduced Order Model and Sparse Measurement

The lifespan of transformers is closely related to their operating temperature. Among the existing temperature acquisition methods, the measurement method cannot obtain the complete temperature field temperature, while the numerical calculation method presents the challenge of significant computational expenses. This study theoretically derived how to determine the real-time temperature distribution of transformer windings based on sparse measurement data and reduced order models and solved sensor layout issues, including the number and placement position of sensors. In this study, the maximum calculation error of the temperature distribution is 1.8 K, and the calculation time is 0.38 seconds. The research findings suggest that multiple modes can contribute to the temperature distribution of a transformer. Under a constant load condition, the calculation of transformer temperature can be achieved by utilizing a temperature sensor positioned at the hot spot in conjunction with the first mode.

A study on table tennis landing point detection algorithm based on spatial domain information

To address the limitations of computer vision-assisted table tennis ball detection, which heavily relies on vision acquisition equipment and exhibits slow processing speed, we propose a real-time calculation method for determining the landing point of table tennis balls. This novel approach is based on spatial domain information and reduces the dependency on vision acquisition equipment. This method incorporates several steps: employing dynamic color thresholding to determine the centroid coordinates of all objects in the video frames, utilizing target area thresholding and spatial Euclidean distance to eliminate interference balls and noise, optimizing the total number of video frames through keyframe extraction to reduce the number of operations for object recognition and landing point detection, and employing the four-frame difference slope method and polygonal area determination to detect the landing point and area of the target object, thereby obtaining precise coordinates and their corresponding areas. Experimental results on the above method on the Jetson Nano development board show that the dynamic color thresholding method achieves a detection speed of 45.3 fps. The keyframe extraction method correctly identifies the landing point frames with an accuracy rate exceeding 93.3%. In terms of drop point detection, the proposed method achieves 78.5% overall accuracy in detecting table tennis ball drop points while ensuring real-time detection. These experiments validate that the proposed method has the ability to detect table tennis ball drop points in real time and accurately in low frame rate vision acquisition devices and real environments.

Queue Length Estimation Based on Probe Vehicle Data at Signalized Intersections

Queue length is one of the important indexes to evaluate the operation efficiency of signalized intersection and also the key parameter of intersection signal control optimization. Traditional queue length estimation models are mostly based on fixed detection equipment, and the models assumptions are too harsh; there are certain limitations. Based on the probe vehicle data, this paper establishes a model of queue length estimation for signalized intersection based on shockwave theory. First, based on the speed and location data of the probe vehicle, the vehicle density is calculated to estimate the intersection stop line. A real-time calculation method of vehicle arrival rate is proposed to improve the applicability of the model. Then, based on the shockwave theory, the meeting time of the queue forming wave and the queue discharging wave are calculated after the green light is on. Finally, the queue length is summed in sections, including the distance between the last queued probe vehicle and the stop line during the red light period, the length of the subsequent vehicles arriving during the residual red light time, and the newly increased queue length within the queue discharging time. This paper uses the VISSIM software to simulate the actual intersection. The simulation results show that when the penetration of probe vehicle is 50%, 25%, and 10%, their corresponding mean absolute relative error are 11.27%, 27.77%, and 39.12%, respectively. It can be seen that with the increase of penetration, the error gradually decreases. The average absolute relative error is within the acceptable range. After analyzing the existing similar methods, although the accuracy of the method proposed in this paper does not reach the highest level, it has the advantages of simple operation, less computation, and good real-time computation. Relevant research results can provide support for traffic control at signalized intersections.

Analysis of the Influence and Propagation Law of Urban Rail Transit Disruptions: A Case Study of Beijing Rail Transit

In the context of the network operation of urban rail transit systems, disruptions caused by signal interruptions influence not only the operation of the service at a single station but also the level of service of the whole network. Moreover, it is even possible to induce the cascading failure of the urban rail transit network. Therefore, it is essential to maintain the real-time dynamic monitoring of abnormal stations in urban rail transit systems for security reasons. Based on the large amounts of automated fare collection (AFC) data, a real-time calculation method to estimate the influence intensity of the passenger flow is presented, the spatiotemporal distribution of the influence characteristics is analyzed, and the propagation law of disruptions in the urban rail transit network is explored. First, the fluctuation threshold of passenger flow in a normal situation for all stations was calculated. Accordingly, abnormal stations influenced by the disruption were identified. Then, an evaluation method for calculating the influence intensity of the passenger flow was proposed. Finally, a real-world case study based on the Beijing rail transit system was conducted. All abnormal stations were identified dynamically and displayed in real time, and the distribution and propagation law of abnormal stations were constructed by spatiotemporal diagrams. The influence intensity of passenger flow was analyzed in detail from the perspective of the whole network and representative stations. The results revealed that transfer stations were more vulnerable to the effects of disruption, and the duration for which these stations were affected was longer than that of ordinary stations. Moreover, short-distance travelers were less affected by the disruption than long-distance travelers. The method proposed in this paper can provide a theoretical basis for rail management departments to grasp the characteristics of passenger flow in real time, formulate disposal measures dynamically, and provide more accurate information services for passengers.

A Real-Time Calculation Method to Improve Boiler Safety in Deep Peak Shaving Cases

To tackle the overheating problem of the heating surface in deep peak shaving, it is urgent to develop working substance (steam) temperature regulation and heating surface safety control technologies that combine combustion and hydrodynamic instability evaluation. This work relies on a 1000 MW boiler involved in deep peak shaving, and adopts CFD numerical simulation technology to obtain reasonable holographic heat load data of the boiler. The heat load data and the working substance side data are coupled to develop a real-time performance calculation model that combines combustion and hydrodynamic steam temperature. Real-time monitoring of the local position of the boiler water wall and the convection heating surface can be achieved through the three steps: heat load screening, heat exchange process calculation, and result display. The results show that through the corresponding expression of on-site industrial parameters and CFD simulation data, the effective analysis, extraction, modeling and optimization of the operation data can be realized for real-time online monitoring and intelligent early warning of the entire working condition. The model error is less than 2 °C and the model can realize early warnings at 5 min, so as to ensure the safety and stability of boiler operation and save the operating cost of the power plant to a certain extent.

Real-time calculation method of transformer winding temperature field based on sparse sensor placement

The Real-time obtain of the transformer winding temperature field is of great significance for understanding the operation status of the transformer. Limited by the spatial sampling rate of the sensor measurement method and the computational efficiency of the Computational Fluid Dynamics (CFD) method, the existing techniques cannot complete the real-time obtain of the transformer winding temperature field well. In this study, an estimator is designed, and used as a bridge to establish the relationship between the sparse measurement data of the winding temperature and the winding temperature field, and the real-time obtain of the winding temperature field is realized. Firstly, the proper orthogonal decomposition (POD) modes are obtained based on the prior information on the winding temperature field. Then, a sparse placement strategy of sensors is designed based on the QR factorization with column pivoting (QR-pivot) method, the measurement matrix is formed, and the sparse measurement data of the winding temperature are obtained. Finally, an estimator is designed to complete the winding temperature field's real-time calculation using the winding temperature's sparse measurement data. The transformer temperature rise test proves the effectiveness of the method. This study can provide a new approach for the real-time obtain of transformer winding temperature field.

A Polynomial Multiplication Accelerator for Faster Lattice Cipher Algorithm in Security Chip

Polynomial multiplication is the most computationally expensive part of the lattice-based cryptography algorithm. However, the existing acceleration schemes have problems, such as low performance and high hardware resource overhead. Based on the polynomial multiplication of number theoretic transformation (NTT), this paper proposed a simple element of Montgomery module reduction with pipeline structure to realize fast module multiplication. In order to improve the throughput of the NTT module, the block storage technology is used in the NTT hardware module to enable the computing unit to read and write data alternately. Based on the NTT hardware module, a precalculated parameter storage and real-time calculation method suitable for the hardware architecture of this paper is also proposed. Finally, the hardware of polynomial multiplier based on NTT module is implemented, and its function simulation and performance evaluation are carried out. The results show that the proposed hardware accelerator can have excellent computing performance while using fewer hardware resources, thus meeting the requirements of lattice cipher algorithms in security chips. Compared with the existing studies, the computing performance of the polynomial multiplier designed in this paper is improved by approximately 1 to 3 times, and the slice resources and storage resources used are reduced by approximately 60% and 17%, respectively.

Real-time trajectory position error compensation technology of industrial robot

In order to meet the requirements of high positioning accuracy and trajectory accuracy of industrial robots in the field of high-precision operation, this paper studied the real-time compensation method of the robot trajectory error used laser tracker to measure the end position of robot in real time. This real-time error calculation method of robot trajectory based on continuous dynamic time warping (CDTW), which was studied to determine the position error of robot trajectory at each moment. Moreover, this paper researched the PID parameter tuning technology of response surface model method based on gray analysis and got a real-time compensation method. The compensation value was fed back to the robot for motion compensation in real time through KUKA RSI. The last, the influence of compensation parameters and period was analyzed and the error compensation experiment of positioning, linear trajectory and arc trajectory were carried out. After compensation, the absolute positioning error of the robot was less than 0.06 mm and the trajectory position error was less than 0.15 mm, which greatly improved the position accuracy of the robot.

Study on Dynamic Probability and Quantitative Risk Calculation Method of Domino Accident in Pool Fire in Chemical Storage Tank Area.

The domino event caused by fire is one of the common accidents in hydrocarbon storage tank farms, which further expands the severity and scope of the accident. Due to the different failure sequence of the storage tanks in a domino accident, the radiant heat generated by the failed storage tank to the target tank is different. Based on the influence of this synergistic effect, this study combined the Monte Carlo algorithm and FSEM, and proposed a fast real-time probability calculation method for a fire domino accident in a storage tank area, for the first time. This method uses the Monte Carlo algorithm to simulate all accident scenarios, and obtains the evolution of multiple escalation fire domino accidents under the synergistic effect according to FSEM, and then calculates the real-time failure probability and risk. Based on a comprehensive analysis of the accident propagation path, this method avoids the problem of a large amount of calculation, and is conducive to the rapid and effective analysis of the fire risk in a storage tank area and the formulation of corresponding risk reduction measures. The effectiveness and superiority of the proposed method were proved by a case study.

Research on real-time power flow calculation method in closed-loop distribution networks

It is less intelligent to calculate the closed-loop power flow of the distribution network by manually inputting the closed-loop power flow parameters. Therefore, it is necessary to study the real-time calculation method of the loop power flow in the distribution network. In this paper, a real-time calculation method is put forward based on the Thévenin’s Theorem. Forward/backward sweep algorithm is used to calculate the power flow of the closed-loop distribution network with the aid of the equivalent impedance and the maximum inrush current. A real-time automatic analysis tool for the closed-loop power flow is developed as well, based on the autonomous decentralized concept. The closed-loop power flow calculation is embedded in the DSCADA system to evaluate the feasibility of the loop-closing operation. Test results show that the proposed method can effectively identify the limit violation conditions within the distribution network, and that the calculation error in closed-loop power flow is small.

A real-time three-phase line loss calculation method for distribution network based on feeder terminal unit

Combined with the monitoring data of the new distribution network Feeder Terminal Unit (FTU), an innovative three-phase real-time line loss calculation method based on the feeder segment rather than the entire feeder as the basic calculation unit is proposed. This method uses the variable structure dissipative network theory, divides the feeder into feeder segments, and conducts mathematical modeling for each equipment in the segment based on the feeder segment. The detailed line loss of each equipment makes the line loss distribution in the system clear at a glance, which is convenient for operation and maintenance personnel to scientifically manage and carry out distribution network line loss analysis and calculation, and provides a favorable basis for further optimization of the distribution network system.

Development of a Real-Time Monitoring and Calculation Method for TBM Disc-Cutter’s Cutting Force in Complex Ground

Abstract Cutting force is an essential parameter of the operating state of tunneling boring machines. In this study, a real-time cutting force monitoring method is proposed for widely used disc-cutters. A microcylindrical strain gauge is embedded in predrilled small boreholes in the bottom and side surface of the two C-shaped cushion blocks on the cutter saddle. The strain gauges are protected by a glue seal, and the sensor leads are protected using a groove and covered by wear-resistant steel. The strain is measured using a wireless strain node and transmitted from the strain node to the wireless gateway connected to a computer. Then, the strain-force relationship of the cushion block is fitted using a laboratory static calibration test. The load on the cushion block is calculated based on the measured cushion block strain. Subsequently, considering the cutter system’s vibration, a multi-degree-of-freedom coupling vibration differential equation of the cutter system is established. The mass matrix, stiffness matrix, and damping matrix of the cutter system are also determined. Finally, a Wilson-θ inverse analysis method is put forward to calculate the cutter’s external load. The developed real-time cutting force monitoring method will not affect cutter replacement, and the cushion block equipped with sensors can be reused. The cutting force identification method, which considers the cutter system vibration, is rigorous in theory, and a useful numerical inverse analysis calculation method is provided.

温控射频消融温度场快速计算方法的研究

温控射频消融温度场快速计算方法的研究

Quantitative Detection of In Vivo Aggregation Degree for Enhanced M2 Macrophage MR Imaging.

In situ self-assembly in vivo can be used in the enhanced diagnosis and therapy of major diseases such as cancer and bacterial infections on the basis of an assembly/aggregation-induced-retention (AIR) effect. However, the aggregation degree (αagg) is a significant parameter for determining the delivery efficiency to lesions in a complex physiological environment and a real-time quantitative calculation of the aggregation degree in vivo is still a great challenge. Here, we developed a magnetic resonance imaging (MRI) method for sensitive and quantitative calculation of αagg with a detection limit of 10-4 M and a bioactivated in vivo assembly (BIVA) magnetic resonance (MR) probe was optimized for enhanced T1-weighted MR imaging of M2 macrophages in tumors. Our MRI quantitative calculation method had a high fitting degree (R2 = 0.987) with the gold standard fluorescence (FL) method. On the basis of the BIVA mechanism of CD206 active targeting and cathepsin B specific tailoring to induce an in situ nanofiber assembly, our optimized BIVA probe exhibited a high intracellular aggregation degree of over 70% and a high in vivo αagg value of over 55%. Finally, the aggregation-enhanced T1 MR signal and the AIR effect both contributed to enhanced T1-weighted MR imaging of M2 macrophages in triple-negative breast cancer. We believe that our αagg real-time quantitative calculation method of MRI will help to further screen and optimize the in vivo enhanced imaging and treatment of the BIVA drug.

Real time reduced order model for angiography fractional flow reserve

Background and ObjectivesFractional flow reserve (FFR) is the gold standard for quantification of coronary stenosis and pressure wire is the gold standard for measuring FFR. Recently, computational fluid dynamics (CFD) methods have been used to compute FFR less invasively using images obtained from coronary angiography. This approach is, however, computationally intensive and solutions to reduce computation time are clearly required. MethodsWe hypothesized that FFR can be calculated instantly using a reduced order model (ROM) derived using response surface method (RSM) for simulation modeling in lieu of the computationally intensive CFD. Specifically, eleven physiological and anatomical factors known to affect FFR were selected as input variables, and Plackett–Burman analysis was performed in conjunction with CFD on model arteries to identify set of variables affecting FFR the most. Based on the Box–Behnken design, a mathematical model was developed to compute FFR using the retained set of variables. ResultsThe model fidelity was tested on a cohort of 90 patients (100 coronary arteries) with known pressure-wire FFR. FFR derived from this ROM had a strong correlation with pressure-wire FFR with sensitivity of 89.4%, specificity of 100% and area under curve of 0.947 (p < 0.05). ConclusionsThe ROM method can be used to reliably calculate FFR in patients with coronary stenosis and able to replace time-consuming CFD-based FFR estimation and provide instead a real-time calculation method.

On real-time creep damage prediction for steam turbine

In this paper, in order to solve the calculation problem of creep damage of steam turbine rotor, a real-time calculation method based on finite element model is proposed. The temperature field and stress field of the turbine rotor are calculated using finite element analysis software. The temperature data and stress data of the crucial positions are extracted. The data of temperature, pressure, rotational speed, and stress relating to creep damage calculation are normalized. A real-time creep stress calculation model is established by multiple regression method. After that, the relation between stress and damage function is analyzed and fitted, and creep damage is calculated in real-time. A creep damage real-time calculation system is constructed for practical turbine engineering. Finally, a numerical simulation experiment is designed and carried out to verify the effectiveness of this novel approach. Contributions of present work are that a practical solution for real-time creep damage prediction of steam turbine is supplied. It relates the real-time creep damage prediction to process parameters of steam turbine, and it bridges the gap between the theoretical research works and practical engineering.

On-orbit real-time calculation method of solar elevation angle of sub-satellite point of Tianwen-1

On-orbit real-time calculation method of solar elevation angle of sub-satellite point of Tianwen-1

Generator stator windings ground fault diagnosis for generator–grid​ directly connected system of floating nuclear power plant

For floating nuclear power plants, the internal power system adopts the generator–grid directly connected structure. Generator ground fault diagnosis enables the protective device to adaptively determine the generator tripping control mode based on the fault degree, and shorten the troubleshooting time by fault location. To accurately calculate the ground fault current under different system operating modes, a real-time grounding capacitance parameters calculation method without injection devices is proposed based on third harmonic voltage. Using the fault component principle, the ground fault current is calculated including the fundamental and the third harmonic components. Through fuzzy membership function, the ground fault degree function is established including the ground fault current and the system overvoltage. It comprehensively reflects the damage degree of both the generator operating security and the system insulation security. According to the 60° phase-band distribution characteristic of the stator windings, a fault coil location method based on the windings’ electric potential distribution characteristics is proposed. PSCAD/EMTDC simulation results show that the proposed method has high computational accuracy.