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Records with Subject: Process Control
Showing records 51 to 75 of 3434. [First] Page: 1 2 3 4 5 6 7 Last
Gearbox Fault Diagnosis Based on Optimized Stacked Denoising Auto Encoder and Kernel Extreme Learning Machine
Zhenghao Wu, Hao Yan, Xianbiao Zhan, Liang Wen, Xisheng Jia
August 2, 2023 (v1)
Keywords: fault diagnosis, gearbox, kernel extreme learning machine, stacked denoising automatic encoder
The gearbox is one of the key components of many large mechanical transmission devices. Due to the complex working environment, the vibration signal stability of the gear box is poor, the fault feature extraction is difficult, and the fault diagnosis accuracy makes it difficult to meet the expected requirements. To solve this problem, this paper proposes a gearbox fault diagnosis method based on an optimized stacked denoising auto encoder (SDAE) and kernel extreme learning machine (KELM). Firstly, the particle swarm optimization algorithm in adaptive weight (SAPSO) was adopted to optimize the SDAE network structure, and the number of hidden layer nodes, learning rate, noise addition ratio and iteration times were adaptively obtained to make SDAE obtain the best network structure. Then, the best SDAE network structure was used to extract the deep feature information of weak faults in the original signal. Finally, the extracted fault features are fed into KELM for fault classification. E... [more]
Fault Diagnosis of Rotating Machinery Bearings Based on Improved DCNN and WOA-DELM
Lijun Wang, Dongzhi Ping, Chengguang Wang, Shitong Jiang, Jie Shen, Jianyong Zhang
August 2, 2023 (v1)
Keywords: Bi-directional Long Short-Term Memory, convolutional neural network, DELM, Efficient Channel Attention Module, fault diagnosis, rotating machinery
A bearing is a critical component in the transmission of rotating machinery. However, due to prolonged exposure to heavy loads and high-speed environments, rolling bearings are highly susceptible to faults, Hence, it is crucial to enhance bearing fault diagnosis to ensure safe and reliable operation of rotating machinery. In order to achieve this, a rotating machinery fault diagnosis method based on a deep convolutional neural network (DCNN) and Whale Optimization Algorithm (WOA) optimized Deep Extreme Learning Machine (DELM) is proposed in this paper. DCNN is a combination of the Efficient Channel Attention Net (ECA-Net) and Bi-directional Long Short-Term Memory (BiLSTM). In this method, firstly, a DCNN classification network is constructed. The ECA-Net and BiLSTM are brought into the deep convolutional neural network to extract critical features. Next, the WOA is used to optimize the weight of the initial input layer of DELM to build the WOA-DELM classifier model. Finally, the featur... [more]
Phenotypic and Genotypic Analysis of Antimicrobial Resistance of Commensal Escherichia coli from Dairy Cows’ Feces
Maksud Kerluku, Marija Ratkova Manovska, Mirko Prodanov, Biljana Stojanovska-Dimzoska, Zehra Hajrulai-Musliu, Dean Jankuloski, Katerina Blagoevska
August 2, 2023 (v1)
Keywords: AmpC, commensal E. coli, dairy cow, ESBL, feces, MIC, resistance
Commensal Escherichia coli has the potential to easily acquire resistance to a broad range of antimicrobials, making it a reservoir for its transfer to other microorganisms, including pathogens. The aim of this study was to determine the prevalence of resistant commensal Escherichia coli isolated from dairy cows’ feces. Phenotypic resistance profiles and categorization were determined by minimum inhibitory concentration (MIC) testing with the broth microdilution method, while the PCR method was used to determine the presence of resistant genes. Out of 159 commensal E. coli isolates, 39 (24.5%) were confirmed to have resistance. According to the MIC values, 37 (97.3%) and 1 (2.7%) isolate were phenotypically categorized as ESBL and ESBL/AmpC, respectively. All isolates showed resistance to ampicillin, while 97.4%, 56.4%, and 36% showed resistance to cefotaxime, ciprofloxacine, and azitromycine, respectively. Not all isolates that showed phenotypic resistance were found to be carrying th... [more]
Observer-Based Approximate Affine Nonlinear Model Predictive Controller for Hydraulic Robotic Excavators with Constraints
Jian Wang, Hao Zhang, Peng Hao, Hua Deng
August 2, 2023 (v1)
Keywords: approximate nonlinear model predictive control, EKF, electro-hydraulic system, robotic excavator, trajectory tracking control
Given the highly nonlinear and strongly constrained nature of the electro-hydraulic system, we proposed an observer-based approximate nonlinear model predictive controller (ANMPC) for the trajectory tracking control of robotic excavators. A nonlinear non-affine state space equation with identified parameters is employed to describe the dynamics of the electro-hydraulic system. Then, to mitigate the plant-model mismatch caused by the first-order linearization, an approximate affine nonlinear state space model is utilized to represent the explicit relationship between the output and input and an ANMPC is designed based on the approximate nonlinear model. Meanwhile, the Extended Kalman Filter was introduced for state observation to deal with the unmeasurable velocity information and heavy measurement noises. Comparative experiments are conducted on a 1.7-ton hydraulic robotic excavator, where ANMPC and linear model predictive control are used to track a typical excavation trajectory. The... [more]
Valve Stiction Detection Method Based on Dynamic Slow Feature Analysis and Hurst Exponent
Linyuan Shang, Yuyu Zhang, Hanyuan Zhang
August 2, 2023 (v1)
Keywords: dynamic slow feature analysis, hurst exponent, process control, valve stiction detection
Valve stiction is the most common root of oscillation faults in process control systems, and it can cause the severe deterioration of control performance and system instability, ultimately impacting product quality and process safety. A new method for detecting valve stiction, based on dynamic slow feature analysis (DSFA) and the Hurst exponent, is proposed in this paper. The proposed method first utilizes DSFA to extract slow features (SFs) from the preprocessed and reconstructed data of the controller output and the controlled process variable; then, it calculates the Hurst exponent of the slowest SF to quantify its long-term correlation; and, finally, it defines a new valve detection index to identify valve stiction. The results obtained from simulations and actual process case studies demonstrate that the proposed method, based on a DSFA−Hurst exponent, can effectively detect valve stiction in control loops.
Disturbance Observer-Based Terminal Sliding Mode Tracking Control for a Class of Nonlinear SISO Systems with Input Saturation
Qiang Zhang, Ping Liu, Yu Chen, Quan Deng, Angxin Tong
August 2, 2023 (v1)
Keywords: control saturation, disturbance observer, feedback linearization, sliding mode control, trajectory tracking control
This paper focuses on the trajectory tracking control for general nonlinear single-input single-output (SISO) systems in which the output is not directly related to the control input. To address the tracking problem with the consideration of possible model uncertainty, external disturbance, and control input saturation, we employ the input-output feedback linearization technique and design a finite-time disturbance observer-based terminal sliding mode controller to improve the tracking performance and enhance the robustness. The stability analysis is carried out by using the Lyapunov method. To alleviate the chattering while achieving an acceptable control performance, a boundary layer method is adopted for the trade-off between the high-frequency control actions and the bounded unavoidable nonzero steady-state error. The proposed method is evaluated on the two typical nonlinear systems, which are fully linearizable and partially linearizable, respectively, and compared to the state-of... [more]
Fault Diagnosis of Bearings Using Wavelet Packet Energy Spectrum and SSA-DBN
Jinglei Qu, Xueli Cheng, Ping Liang, Lulu Zheng, Xiaojie Ma
August 2, 2023 (v1)
Keywords: bearing fault diagnosis, classification problem, DBN, SSA, wavelet packet energy spectrum
To enhance fault characteristics and improve fault detection accuracy in bearing vibration signals, this paper proposes a fault diagnosis method using a wavelet packet energy spectrum and an improved deep confidence network. Firstly, a wavelet packet transform decomposes the original vibration signal into different frequency bands, fully preserving the original signal’s frequency information, and constructs feature vectors by extracting the energy of sub-frequency bands via the energy spectrum to extract and enhance fault feature information. Secondly, to minimize the time-consuming manual parameter adjustment procedure and increase the diagnostic accuracy, the sparrow search algorithm−deep belief network method is proposed, which utilizes the sparrow search algorithm to optimize the hyperparameters of the deep belief networks and reduce the classification error rate. Finally, to verify the effectiveness of the method, the rolling bearing data from Casey Reserve University were selecte... [more]
Analysis Method of Full-Scale Pore Distribution Based on MICP, CT Scanning, NMR, and Cast Thin Section Imaging—A Case Study of Paleogene Sandstone in Xihu Sag, East China Sea Basin
Jinlong Chen, Zhilong Huang, Genshun Yao, Weiwei Zhang, Yongshuai Pan, Tong Qu
August 2, 2023 (v1)
Keywords: CT cylinder model, CT scan, full-scale pore distribution, mercury withdrawal, NMR, tortuosity index
Using different experimental methods, the pore radius ranges vary greatly, and most scholars use a single experiment to study pore structure, which is rarely consistent with reality. Moreover, the numerical models used in different experiments vary and cannot be directly compared. This article uniformly revised all experimental data into a cylinder model. Quantitative analysis of the full-scale pore distribution is established by mercury withdrawal−CT data, and semi-quantitative distribution is obtained by mercury−NMR−cast thin section imaging. In this paper, we introduce the tortuosity index (τ) to convert the CT ball-and-stick model into a cylinder model, and the pore shape factor (η) of the cast is used to convert the plane model into the cylinder model; the mercury withdrawal data is applied to void the influence of narrow throat cavities, and the NMR pore radius distribution is obtained using the mercury-T2 calibration method. Studies have shown that the thickness of bound water i... [more]
Temperature−Electrokinetic Co-Driven Perfluorooctane Sulfonic Acid (PFOS) Adsorption on Geo-Adsorbents
Yuzhou Yin, Yongping Shan, Dong Ma, Liuqing Yang, Mingxiu Zhan, Ping Liu, Benzhen Lou, Bo Zhang, Wentao Jiao, Lichu Yin
July 13, 2023 (v1)
Keywords: adsorption kinetics, adsorption thermodynamics, electrokinetic, electroosmotic flow, PFOS, temperature
Per- and polyfluoroalkyl substances (PFAS) have concerned the public due to their worldwide distribution and the threat they pose to drinking water safety and human health. Temperature and DC field-induced electroosmotic flow (EOF) are powerful tools to regulate organic contaminant adsorption and control PFOS (as a typical PFAS) transport in porous media. However, the co-driven mechanisms of temperature−electrokinetic transport of contaminants are still unclear. Here, we investigated the synergistic mechanisms of temperature−electrokinetic co-driven PFOS adsorption on zeolite and activated carbon as model geo-adsorbents. We found that DC fields increased PFOS adsorption on activated carbon by up to 19.8%, while they decreased PFOS adsorption on zeolite by up to 21.4%. Increasing the temperature decreased the adsorption of PFOS by activated carbon and zeolite. The temperature and electrokinetic synergistically drive EOF velocity to control PFOS adsorption. Synergistic mechanisms of temp... [more]
Optimal Control of Technological Processes
Anatoliy M. Tsirlin, Alexander I. Balunov
July 13, 2023 (v1)
Keywords: features of technological objects, maximum stability of linear systems, pure delay, robustness
The paper formulates conditions under which the roots closest to the imaginary axis (critical roots) of the characteristic equation of a linearized system are real for the maximum possible degree of stability of the closed-loop control system of a technological process with pure delay. For the parameters of the controllers corresponding to the maximum degree of stability, these roots are multiples. Their multiplicity order is one more than the number of coefficients in the transfer function of the controller. It is demonstrated that for a typical technological control object, these conditions are satisfied for all “serial” control laws. This allowed for obtaining analytical expressions for optimal settings and limiting degrees of stability as functions of object parameters for typical dynamic characteristics of technological processes. The paper considers the problem of robust stability for control systems with an object containing pure delay. It has been proven that in the maximum sta... [more]
Experimental Investigation on Pressure-Control Characteristics of Liquid Hydrogen Tank Based on Active and Passive Thermodynamic Venting System Technology
Zhenjun Zhou, Jun Wu, Shaohua Zhang, Mengmeng Gong, Xin Liu
July 13, 2023 (v1)
Keywords: active and passive pressure control, liquid hydrogen, TVS, ullage pressure
Pressure control while minimizing the mass loss of liquid hydrogen is one of the key technologies required for the long-term storage of cryogenic propellants in microgravity in space, and the use of a thermodynamic venting system (TVS) has been considered as an effective means to solve this problem. In order to investigate the characteristics of pressure control by TVS technology, a cryogenic test platform for liquid hydrogen that integrated active and passive TVS was set up, a spray-bar exchanger and vapor-cooling screen were used to eliminate thermal stratification and realize the reuse of cold energy. Ten pressure-control tests using passive TVS (PTVS), mixing and active TVS (ATVS) strategies with heating powers of 0 W, 40 W and 80 W, were carried out. The single cycle time under different strategies, the effect of heating power on single cycle time, and the comparison of volume of the venting GH2 in different tests were analyzed in detail, the research showed that TVS technology co... [more]
The Application of Photovoltaic-Electric Spring Technology to Rural Power Grids
Zhibin Cui, Junsheng Shi, Guangpeng Li, Zihan Yuan, Dehua Zang, Lidi Wang
July 13, 2023 (v1)
Keywords: electric spring, photovoltaic system, photovoltaic-grid-connected, PI control strategy, rural power, voltage fluctuations
Rural power grids are essential for rural development, impacting the lives of farmers, the agricultural economy, and the overall efficiency of agricultural production. To ensure the reliable operation of these grids, finding ways to provide high-quality power is imperative. In recent years, the penetration rate of distributed photovoltaic (PV) in the distribution network has been increasing. When the output of PV and load are not matched, the voltage fluctuation of the network affects the safe and stable operation of the distribution network. In this study, we propose that the stable operation of rural power grids can be achieved by employing a photovoltaic-electric spring (PV-ES) device. A state space model of PV-ES is established and a single PV-ES voltage control method, based on a PI controller, is proposed, taking a rural user household with a monthly power consumption of about 120 access to distributed power supply as an example. We analyzed the device’s effectiveness in addressi... [more]
Production Capacity Variations of Horizontal Wells in Tight Reservoirs Controlled by the Structural Characteristics of Composite Sand Bodies: Fuyu Formation in the Qian’an Area of the Songliao Basin as an Example
Ruhao Liu, Yu Sun, Xinrui Wang, Baiquan Yan, Limin Yu, Zhao Li
July 13, 2023 (v1)
Keywords: capacity difference evaluation, composite sand body structure, control factors, Fuyu reservoir
In order to improve the combined exploitation efficiency of horizontal and vertical wells, and given the fact that the complex and varied spatial structure of sand bodies in the Fuyu oil layer in the Qian’an area of Songliao Basin leads to significant differences in production characteristics of horizontal wells, the sand body types and internal spatial structure are finely dissected according to the theory of configuration analysis, and the internal spatial structure is divided into three configuration styles: spatial clipping type, overlapping type, and separation type. Then, by comparing the productivity characteristics of horizontal wells with different configurations of sand bodies, combined with the analysis of fluid flow law under horizontal well volume fracturing, a main fracture−fracture network−matrix coupled fluid flow model in a tight reservoir based on composite sand body configuration is established. Combined with the actual volume fracturing the horizontal well area, the... [more]
Study on the Stability of Coal Pillars in a Gob-Side Two-Entry Arrangement of Different Layers in Fully Mechanized Caving and the Zonal Linkage Control of “Heteromorphic” Surrounding Rock
Hui Li, Sheng Gao, Dongdong Chen, Shengrong Xie, Yiyi Wu, Shaohua Feng, Zaisheng Jiang, Fangfang Guo
July 7, 2023 (v1)
Keywords: broken coal, gob-side entry driving (GED), grouting, roadway surrounding rock control, section coal pillar width
To solve the problem of considerable deformation of the tailgate in a fully mechanized caving face, the position of the main roof fracture line is first obtained by theoretical calculation, combined with the results of a similar simulation test and numerical simulation analysis. The width of the section coal pillar in the tailgate is determined to be 11.5 m. Based on the distribution characteristics of deviatoric stress and the plastic zone of surrounding rock, combined with the location characteristics and geological conditions, a new zoning control design approach is proposed, a “two pillars, three zones, and three parts” arrangement for the surrounding rock of the tailgate. The targeted two-entry support design is carried out following common engineering practices. Mine pressure monitoring data were used to verify the results of the new two-entry design. The comparison shows that the supporting technology can effectively control the considerable deformation of the surrounding rock,... [more]
Innovative Techniques for Safety, Reliability, and Security in Control Systems
Francisco-Ronay López-Estrada, Guillermo Valencia-Palomo
July 7, 2023 (v1)
Control systems have become a critical component in the advancement of many engineering and science fields [...]
Study on Multi-Mode Switching Control of Intelligent Suspension under Full Road Section
Zhaole Qu, Jianze Liu, Yang Li, Fazhan Yang, Jiang Liu
July 7, 2023 (v1)
Keywords: active suspension, adaptive Kalman filtering algorithm, BP-PID control, GA-LQR control, multi-mode switching
The safety, comfort, and energy feedback of active suspension in a single control mode is mutually restricted. To meet the needs of drivers and passengers for vehicle driving performance under different road conditions, this paper proposes a multi-mode switching control strategy of an intelligent suspension system, aiming at improving the stability and comfort of vehicles under different road conditions. In this paper, the adaptive Kalman filter algorithm with a forgetting factor is used to estimate the road input. The accuracy of the algorithm in estimating the road input is verified by simulation and experiment. The single-double threshold logic judgment method is used to formulate the switching rules between each working mode. In the controller, the PID control of the BP neural network and the LQR control optimized by GA are used to optimize and adjust the vehicle driving performance indexes in different modes, which effectively solves the problem of limited adaptability of suspensi... [more]
Research on Assembly Method of Threaded Fasteners Based on Visual and Force Information
Yibang Zhou, Xiaoyong Wang, Lanzhu Zhang
July 7, 2023 (v1)
Keywords: compliant control, force sensor, position and orientation estimation, threaded fasteners assembly, vision
Threaded fastening operations are widely used in assembly and are typically time-consuming and costly. In low-volume, high-value manufacturing, fastening operations are carried out manually by skilled workers. The existing approaches are found to be less flexible and robust for performing assembly in a less structured industrial environment. This paper introduces a novel algorithm for detecting the position and orientation of threaded holes and a new method for tightening bolts. First, the elliptic arc fitting method and the three-point method are used to estimate the initial position and orientation of the threaded hole, and the force impact caused by switching from the free space to the constrained space during bolt tightening is solved. Second, by monitoring the deformation of passive compliance, the position information is introduced into the control process to better control the radial force between the bolt and the threaded hole in the tightening process. The constant force contr... [more]
Monitoring Temperature Profile and Drying Kinetics of Thin-Layer Banana Slices under Controlled Forced Convection Conditions
Baher M. A. Amer, Mostafa M. Azam, AbdelGawad Saad
July 7, 2023 (v1)
Keywords: banana, diffusivity, drying kinetics, infrared camera, shrinkage, thin-layer
The drying kinetics of banana slices were examined in a forced convection dryer using an infrared camera to monitor the temperature profile and drying kinetics under control conditions. The air temperature was tested at 40 °C, 50 °C, 60 °C, and 70 °C and the air velocity at 0.2 m/s, 0.5 m/s, and 0.75 m/s, with initial moisture contents of the banana ranging from 76−80% wet basis. The thicknesses of the banana slices being dried were 2, 4, 6, and 8 mm. The optimum drying conditions for the highest drying rate and best color were found to be a temperature of 70 °C, an air velocity of 0.75 m/s, a low relative humidity of 5 to 7%, and banana slices with a thickness of 2 mm. As the air temperature increased, the drying rate and shrinkage also increased. Shrinkage varies concerning moisture loss, and the reduction in radial dimension of banana slices was around 17−23% from the original slice before drying. An empirical mathematical equation was derived by applying the technique of multiple l... [more]
Special Issue: Intelligent Control and Maintenance of Fluid Component and System
Yong Zhu, Tao Zhou, Qiang Gao, Xiaoming Yuan, Chuan Wang, Bo Hu
July 7, 2023 (v1)
Fluid components and systems are major components of modern mechanical equipment and have been widely used in various fields such as engineering machinery, rotating machinery, and hydraulic machinery [...]
Detecting Plant-Wide Oscillation Propagation Effects of Disturbances and Faults in a Chemical Process Plant Using Network Topology of Variance Decompositions
Dhan Lord B. Fortela, Ashley P. Mikolajczyk
July 7, 2023 (v1)
Keywords: chemical process control, network analysis, oscillation propagation analysis
This work demonstrates for the first time the application of network topology of variance decompositions in analyzing the connectedness of chemical plant process variable oscillations arising from disturbances and faults. Specifically, the time-based connectedness and frequency-based connectedness of variables can be used to compute the net pairwise dynamic connectedness (NPDC), which originated as a volatility spillover index for financial markets studies in the field of econometrics. This work used the anomaly-detection benchmark Tennessee-Eastman chemical process (TEP) dataset, which consists of 41 measured variables and 11 manipulated variables subjected to various faulty operating conditions. The data analytics was performed using key functions from the R-package ‘ConnectednessApproach’ that implements connectedness computations based on time and frequency. The NPDC coefficient matrices were then transformed into network adjacency matrices for the rendering of the network topology... [more]
NN-Based Parallel Model Predictive Control for a Quadrotor UAV
Jun Qi, Jiru Chu, Zhao Xu, Cong Huang, Minglei Zhu
July 7, 2023 (v1)
Keywords: adaptive learning, MPC, neural networks, parallel control, Q-UAVs
A novel neural network (NN)-based parallel model predictive control (PMPC) method is proposed to deal with the tracking problem of the quadrotor unmanned aerial vehicles (Q-UAVs) system in this article. It is well known that the dynamics of Q-UAVs are changeable while the system is operating in some specific environments. In this case, traditional NN-based MPC methods are not applicable because their model networks are pre-trained and kept constant throughout the process. To solve this problem, we propose the PMPC algorithm, which introduces parallel control structure and experience pool replay technology into the MPC method. In this algorithm, an NN-based artificial system runs in parallel with the UAV system to reconstruct its dynamics model. Furthermore, the experience replay technology is used to maintain the accuracy of the reconstructed model, so as to ensure the effectiveness of the model prediction algorithm. Furthermore, a convergence proof of the artificial system is also giv... [more]
Actuator FDI Scheme for a Wind Turbine Benchmark Using Sliding Mode Observers
Vicente Borja-Jaimes, Manuel Adam-Medina, Jarniel García-Morales, Gerardo Vicente Guerrero-Ramírez, Betty Yolanda López-Zapata, Eduardo Mael Sánchez-Coronado
July 7, 2023 (v1)
Keywords: fault detection and isolation (FDI), sliding mode observer (SMO), wind turbines
This paper proposes a fault detection and isolation (FDI) scheme for a wind turbines subject to actuator faults in both the pitch system and the drive train system. The proposed scheme addresses fault detection and isolation problems using a fault estimation approach. The proposed approach considers the use of a particular class of sliding mode observers (SMOs) designed to maintain the sliding motion even in the presence of actuator faults. The fault detection problem is solved by reconstructing the actuator faults through an appropriate analysis of the nonlinear output error injection signal, which is required to keep the SMO in a sliding motion. To ensure accurate fault reconstruction, only two conditions are required, namely that the faults are bounded and they meet the matching condition. A scheme based on a bank of SMOs is proposed to solve the fault detection and isolation problem in the pitch system. For the drive train system, a scheme using only one SMO is proposed. The perfor... [more]
Design of Photovoltaic Power Generation Servo System Based on Discrete Adaptive Network Dynamic Surface Control Technology
Xiaowei Xu, Ding Nie, Wenhua Xu, Ke Wang, Shan Chen, Yongjie Nie, Xiao Fu, Wan Xu
July 4, 2023 (v1)
Keywords: controller, discrete-time system, dynamic surface, photovoltaic power generation, quantizer, servo system
In recent years, under the development of the dual carbon goal, the energy crisis has become increasingly serious, and China has also experienced serious power rationing. However, the research on dynamic surface control technology in solar tracking systems in nonlinear control systems is mostly based on continuous-time systems, while adaptive dynamic surface control based on discrete-time nonlinear control systems can describe an actual control system more accurately in the production process. It can effectively suppress interference with extremely high stability and safety. To solve the problem of low efficiency in photovoltaic power generation, this research first built a photovoltaic power generation servo system model based on the parameter of uncertainty. Then, a discrete adaptive neural network dynamic surface (DANNDS) controller was designed to solve the problems in the design of the traditional backstepping method. Finally, based on the designed method of a dynamic surface cont... [more]
Dynamic Optimization of Variable Load Process for Combined Heat and Power Unit Based on Sequential Quadratic Programming and Interior Point Method Alternating Solution Method
Yuehua Huang, Qing Chen, Lei Zhang, Zihao Zhang, Xingtao Liu, Jintong Tu
July 4, 2023 (v1)
Keywords: convergence depth control, dynamic optimization, IPM-SQP alternate solution, orthogonal collocation method, variable load control process
Aiming at the problem that the modeling and solving method of combined heat and power (CHP) unit variable load control process is challenging to meet the demand for efficient analysis of complex systems, this paper proposes a method based on sequential quadratic programming and interior point method (SQP-IPM) alternating solution for dynamic optimization of the CHP unit variable load process. Firstly, by constructing the CHP unit mechanism model, multi-variable coordination control constraints, and output variable process constraints, the dynamic optimization proposition of the CHP unit variable load control process is formed. Then, the large-scale nonlinear programming (NLP) problem formed by using the orthogonal configuration method to discrete the state and control variables is optimally solved using the IPM-SQP alternating solution method. Further, from the perspective of balancing the accuracy of the solution and computational efficiency, the flexible convergence depth control (CD... [more]
Coupled Excitation Strategy for Crack Initiation at the Adhesive Interface of Large-Sized Ultra-Thin Chips
Tao Wu, Xin Chen, Shiju Wen, Fangsong Liu, Shengping Li
July 4, 2023 (v1)
Keywords: cohesion zone model, coupling excitation of crack initiation, non-destructive chip peeling of large-size ultra-thin chip, peeling angle
The initial excitation of interface crack of large-size ultra-thin chips is one of the most complicated technical challenges. To address this issue, the reversible fracture characteristics of a silicon-based chip (chip size: 1.025 mm × 0.4 mm × 0.15 mm) adhesive layer interface was examined by scanning electron microscope (SEM) tests, and the characteristics of a cohesive zone model (CZM) unit were obtained through peel testing. The fitting curve of the elastic bilinear model was in high agreement with the experimental data, with a correlation coefficient of 0.98. The maximum energy release rate required for stripping was GC = 10.3567 N/m. Subsequently, a cohesive mechanical model of large-size ultra-thin chip peeling was established, and the mechanical characteristics of crack initial excitation were analyzed. The findings revealed that the larger deflection peeling angle in the peeling process resulted in a smaller peeling force and energy release rate (ERR), which made the initial c... [more]
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