Study on Impact of Vibration Direction on Linear Vibration Screening Effect

2012 ◽  
Vol 226-228 ◽  
pp. 186-190
Author(s):  
Yue Min Zhao ◽  
Ke Wang ◽  
Liang Dong ◽  
Bo Zhang ◽  
Xu Liang Yang ◽  
...  
Keyword(s):  
Sieve Plate ◽  
Test Results ◽  
Simulation Test ◽  
Screening Process ◽  
Vibration Direction ◽  
Screening Effect ◽  
Direction Angle ◽  
Movement Characteristics ◽  
Screening Efficiency ◽  
Dip Angle

Based on Hertz-Mindlin contact model in software EDEM by discrete element method, using linear vibrating screen 360 mm×600 mm, movement characteristics of particle group on sieve plate and law of particles going through sieve plate were studied in screening process of coal in certain conditions, which were as follows: dip angle was 0 °, amplitude was 5 mm, frequency was 11 Hz. The simulation test results show that there are important influences of vibration direction on screening process. And influence law of vibration direction on screening effect was revealed finally. The paper also gained mathematical model between particle group’s screening efficiency and vibration direction angle, and mathematical models of particles easy or hard to sieve and material between average movement speeds and vibration direction angle.

Numerical Simulation of Vibration Sieve Based on DEM

2012 ◽  
Vol 482-484 ◽  
pp. 1358-1361
Author(s):  
Yue Jing Zhao ◽  
Zhi Ying Qin
Keyword(s):  
Numerical Simulation ◽  
Discrete Element Method ◽  
Special Kind ◽  
Particle Flow ◽  
Particle Flow Code ◽  
Screening Process ◽  
Vibration Direction ◽  
Sieve Effect ◽  
Screening Efficiency ◽  
Particle Group

Vibrating sieve is a special kind of equipment which used to grading materials according to particle granularity. By the vibration acted on the sieve, the materials are loosed, are divided into layers, are transported and are permeated the sieve to screen the materials. Discrete Element Method (DEM) has been an effective numerical method to research the granule system motion. Using Particle Flow Code (PFC) based DEM, the screening process, the particle group motions on the screen, are simulated. How the amplitude, the frequency of vibration, the vibration direction angle, the decline degree of sieve effect screening efficiency are presented.

scholarly journals Study on screening performance and parameter optimization of vibrating-dewatering screen

2021 ◽  
Vol 13 (9) ◽  
pp. 168781402110465
Author(s):  
Zhanfu Li ◽  
Peiyu Jia ◽  
Kunyuan Li ◽  
Xin Tong ◽  
Zhihong Wu
Keyword(s):  
Optimal Parameter ◽  
Slope Angle ◽  
Physical Experiment ◽  
Simulation Test ◽  
Processing Efficiency ◽  
Screening Process ◽  
Factors Affecting ◽  
Experiment Platform ◽  
Screening Performance ◽  
Screening Efficiency

In this paper, the dewatering and screening process of vibrating-dewatering screen is studied by the combination of simulation test and physical experiment. The simulation model of dewatering screening process is established by the method of computational fluid dynamics (CFD) and discrete element method (DEM). Subsequently, the screening efficiency and processing efficiency are defined as evaluating indexes for performance of dewatering and screening. Four parameters of amplitude, vibration frequency, vibrating direction angle and slope angle of screen surface are selected for single factor simulation test, and the variation of dewatering and screening performance under different parameters is obtained. Finally, the reliability of the simulation results is verified by the physical experiment platform, and significant factors affecting the evaluation index of the vibrating-dewatering screen parameters and the optimal parameter combination are obtained by orthogonal test.

scholarly journals AI-Empowered Computational Examination of Chest Imaging for COVID-19 Treatment: A Review

2021 ◽  
Vol 4 ◽  
Author(s):  
Hanqiu Deng ◽  
Xingyu Li
Keyword(s):  
False Negative ◽  
Screening Tools ◽  
Polymerase Chain Reaction Test ◽  
Test Results ◽  
First Case ◽  
Lung Scan ◽  
Screening Efficiency ◽  
Polymerase Chain ◽  
Chain Reaction Test ◽  
Full Swing

Since the first case of coronavirus disease 2019 (COVID-19) was discovered in December 2019, COVID-19 swiftly spread over the world. By the end of March 2021, more than 136 million patients have been infected. Since the second and third waves of the COVID-19 outbreak are in full swing, investigating effective and timely solutions for patients’ check-ups and treatment is important. Although the SARS-CoV-2 virus-specific reverse transcription polymerase chain reaction test is recommended for the diagnosis of COVID-19, the test results are prone to be false negative in the early course of COVID-19 infection. To enhance the screening efficiency and accessibility, chest images captured via X-ray or computed tomography (CT) provide valuable information when evaluating patients with suspected COVID-19 infection. With advanced artificial intelligence (AI) techniques, AI-driven models training with lung scans emerge as quick diagnostic and screening tools for detecting COVID-19 infection in patients. In this article, we provide a comprehensive review of state-of-the-art AI-empowered methods for computational examination of COVID-19 patients with lung scans. In this regard, we searched for papers and preprints on bioRxiv, medRxiv, and arXiv published for the period from January 1, 2020, to March 31, 2021, using the keywords of COVID, lung scans, and AI. After the quality screening, 96 studies are included in this review. The reviewed studies were grouped into three categories based on their target application scenarios: automatic detection of coronavirus disease, infection segmentation, and severity assessment and prognosis prediction. The latest AI solutions to process and analyze chest images for COVID-19 treatment and their advantages and limitations are presented. In addition to reviewing the rapidly developing techniques, we also summarize publicly accessible lung scan image sets. The article ends with discussions of the challenges in current research and potential directions in designing effective computational solutions to fight against the COVID-19 pandemic in the future.

scholarly journals Performance Comparison of 2L-VSC, 3L-NPC, and 3L-MMC Converter Topologies for Interfacing Grid-Connected Systems

2021 ◽  
Author(s):  
Victor R. F. B. de Souza ◽  
Luciano S. Barros ◽  
Flavio B. Costa
Keyword(s):  
Reactive Power ◽  
Harmonic Distortion ◽  
Performance Comparison ◽  
Test Results ◽  
Multilevel Converter ◽  
Simulation Test ◽  
Comparative Performance ◽  
Higher Power ◽  
Converter Topologies ◽  
Level Converter

Nowadays, power converters play a fundamental role in the conditioning and processing of active and reactive power, and are directly related to power quality indexes. In this sense, new multi-level converter topologies have been integrated in order to provide higher power processing capacity with lower harmonic distortion, switch stress, heating, and losses. The use of these structures compared to conventional two-level converters is especially suitable for high power of the order of megawatt. Considering the relevance of this approach, this paper presents a comparative performance analysis among the conventional two-level topology (2L-VSC) and two multilevel topologies in a grid-connected system: neutral point clamped (NPC) and modular multilevel converter (MMC). Simulation test results present the impacts on voltages and currents for the switches and the whole system, as well as the evaluation of the total harmonic distortion (THD) in order to highlight the crucial points of each topology for this kind of application.

Numerical simulation of particle screening efficiency of large multi-layer vibrating screen based on discrete element method

2021 ◽  
pp. 095440892110606
Author(s):  
Yujia Li ◽  
Peng Zhao ◽  
Li Mo ◽  
Tao Ren ◽  
Minghong Zhang
Keyword(s):  
Discrete Element Method ◽  
Environmental Protection ◽  
Inclination Angle ◽  
Discrete Element ◽  
Physical Parameters ◽  
Screening Process ◽  
Efficient Operation ◽  
Vibrating Screen ◽  
Screening Efficiency ◽  
Element Method

With the increasing requirements for energy conservation and environmental protection, multi-layer vibrating screens have become hot issues. Compared with single-layer vibrating screens, multi-layer vibrating screens has much better performance in terms of processing effect, treatment capacity, and environmental protection. The research on the physical parameters of the multi-layer vibrating screen is of great significance to the actual production. However, analysis and simulation studies of multi-layer vibrating screens are limited. In this paper, the screening process of wet particles on a multi-layer vibrating screen was simulated by using the discrete element method. The characteristics and application scope of the two vibration modes were analyzed. The particle penetration rate, the number of collisions, and the distribution of the particles under 23 combinations of structures and vibration parameters were investigated. The influence of different parameters on screening performance was analyzed. Several optimal combinations of frequency, amplitude and screen inclination angle under different working conditions were obtained. The screening efficiency of the balanced elliptic motion is higher than that of the linear motion. The best combination of the three parameters is 4 mm amplitude, 20 Hz frequency, and 3° inclination angle. The efficiency is higher when the particles follow a distribution of arithmetic on the screen. This study provides a reference for the efficient operation and optimal design of large multi-layer screening equipment.

scholarly journals Dynamic Characteristics of a Vibrating Flip-Flow Screen and Analysis for Screening 3 mm Iron Ore

2020 ◽  
Vol 2020 ◽  
pp. 1-12 ◽  
Author(s):  
Chi Yu ◽  
Xinwen Wang ◽  
Kunfeng Pang ◽  
Guofeng Zhao ◽  
Wenpeng Sun
Keyword(s):  
Dynamic Model ◽  
Iron Ore ◽  
Coarse Particles ◽  
Screening Length ◽  
Screening Process ◽  
Fine Grained ◽  
Screening Performance ◽  
Proposed Model ◽  
Screening Efficiency ◽  
Multistage Sampling

Deep dry screening is the key unit in mineral processing. A vibrating flip-flow screen (VFFS) can provide effective solutions for screening fine-grained minerals, and it has been extensively used in many industrial fields. An accurate dynamic model of VFFS considering the influence of materials is significant for its dynamic analysis and screening process research, but it has rarely been studied in detail. In this paper, an improved dynamic model of VFFS is proposed and its dynamic equations are solved to find the reasonable operating condition, and experiments are carried out to verify the reasonability of the proposed model under no-load and loading materials conditions. Furthermore, the method of multistage sampling and multilayer screening is also applied to evaluate the screening performance of iron ore at 3 mm cut size on VFFS. Results show that when the mass of materials, relative amplitude, and operating frequency have values of 107 kg, about 6 mm and 80.79 rad/s, respectively, the screening efficiency gradually increases with an increase of screening length, reaching 89.05%; however, it does not change much when the screening length exceeds 1900.8 mm. Additionally, the misplaced materials of coarse particles will continue to increase as the screening length increases. This provides theoretical and technical support for the optimization of the length of the VFFS.

scholarly journals Numerical Investigation on the Sieving Performance of Elliptical Vibrating Screen

Processes ◽  
2020 ◽  
Vol 8 (9) ◽  
pp. 1151
Author(s):  
Zhiquan Chen ◽  
Xin Tong ◽  
Zhanfu Li
Keyword(s):  
Major Axis ◽  
The Finite Element Method ◽  
Semi Major Axis ◽  
Vibration Direction ◽  
Maximum Deformation ◽  
Vibrating Screen ◽  
Performance Indexes ◽  
Screening Efficiency ◽  
Axis Length ◽  
Element Method

Screening techniques have been widely deployed in industrial production for the size-separation of granular materials such as coal. The elliptical vibrating screen has been regarded as an excellent screening apparatus in terms of its high screening efficiency and large processing capacity. However, its fundamental mechanisms and operational principles remain poorly understood. In this paper, the sieving process of an elliptical vibrating screen was numerically simulated based on the discrete element method (DEM), and an approach coupling the DEM and the finite element method (DEM–FEM) was introduced to further explore the collision impact of materials on the screen deck. The screening time, screening efficiency, maximum stress and maximum deformation were examined for the evaluation of sieving performance. The effects of six parameters—length of the semi-major axis, length ratio between two semi-axes, vibration frequency, inclination angle, vibration direction angle and vibration direction—on different sieving results were systematically investigated in univariate and multivariate experiments. Additionally, the relationships among the four performance indexes were discussed and the relational functions were obtained. The conclusions and methodologies presented in this work could be of great significance for the design and improvement of elliptical vibrating screens.

Analysis and Simulation System for Stepper Motor Controller

2013 ◽  
Vol 457-458 ◽  
pp. 938-943
Author(s):  
Rong Chun Sun ◽  
Ming Qiu Li
Keyword(s):  
Precise Measurement ◽  
Simulation System ◽  
Test Results ◽  
Cnc Machine ◽  
Simulation Test ◽  
Test Analysis ◽  
Motor Controller ◽  
Stepper Motors ◽  
Motor Load ◽  
The Many

Stepper motors are wildly used in the many fields, such as CNC machine, motion robot, aeronautics and astronautics. To realize online precise measurement, error analysis and verification of control strategy, it is necessary to sample and analyze the driving signals of motors, and simulate mechanical motion in a computer. So a test, analysis and simulation system of stepper controllers was designed. Driving signals of stepper motors are synchronously sampled and analyzed by the unit of acquisition and analysis. A connecting Motherboard was used to link the various parts and finish the data transmission. The working states of motor divers under load were simulated by connecting motor driver to the simulation board of motor load. In the industrial computer, the control effects of multi-axis control system were displayed by 3D simulation. Test results show that the system is stable and reliable, and has a certain application value.

A Design of MIMU/GPS Integrated Navigation System

2013 ◽  
Vol 278-280 ◽  
pp. 1719-1722 ◽  
Author(s):  
Xiao Yu Zhang ◽  
Chun Lei Song
Keyword(s):  
Navigation System ◽  
Inertial Measurement Unit ◽  
High Performance ◽  
Inertial Navigation System ◽  
Measurement Unit ◽  
Integrated Navigation ◽  
Test Results ◽  
Simulation Test ◽  
Integrated Navigation System ◽  
Navigation Algorithm

A new scheme of small integrated navigation system based on micro inertial measurement unit (MIMU), global position system (GPS) is presented. The characteristic of these sensors and the structure of system are introduced respectively. The TI high performance floating point DSP TMS320C6713B is used as core processor, which is designed to realize both the data collecting and the navigation calculating. According to the error models of inertial navigation system, an integrated navigation algorithm used Kalman filter is proposed to fuse the information from all of the sensors. The simulation test results show the feasibility of the system design.

Test and Simulation System of Multi-Axis Controller

2013 ◽  
Vol 860-863 ◽  
pp. 1069-1072
Author(s):  
Rong Chun Sun ◽  
Yan Xin Yu
Keyword(s):  
Control System ◽  
Error Analysis ◽  
Real Time ◽  
Control Strategy ◽  
Simulation System ◽  
Test Results ◽  
Simulation Test ◽  
Motion Mechanism ◽  
Simulation Unit ◽  
Time Acquisition

To realize the online error analysis and verification of control strategy, it is necessary to simulate the states of the motion mechanism, and accurately to obtain the motion relationship between multi-axis and between motors. So a test and simulation system of multi-axis controller was designed. The system consists of a unit of real-time acquisition and analysis, a simulation unit of motor loads, a motherboard and a computer. Motor driving signals for multi channels are synchronously sampled and analyzed by the unit of acquisition and analysis. Motherboard is used to link the various parts. The working states of motor divers under loads are simulated by simulating the motor loads. In the industrial computer, the control effects of multi-axis control system are displayed by 3D simulation. Test results show that the system is stable and reliable, and has a certain application value.

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