An integrated analysis is required to evaluate the performance of control algorithms used in power take-off (PTO) systems for floating wave energy converters (FWECs). However, research on PTO systems based on the existing hydraulic device has mainly focused on the input power generation performance rather than on obtaining maximum power through hydraulic device-based electrical load control. The power generation performance is analyzed based on the control variables of the existing torque control algorithm (TCA); however, the amount of power generation for each control variable changes significantly based on the cycle of wave excitation moments. This paper proposes a control algorithm to obtain the maximum power by modeling a hydraulic-device-based integrated FWEC. It also proposes a TCA that can obtain the maximum power regardless of the period of wave excitation moment. The proposed TCA continuously monitors the power generation output and changes the PTO damping coefficient in the d... [more]

Most photovoltaic (PV) plants conduct operation and maintenance (O&M) by periodical inspection and cleaning. Such O&M is costly and inefficient. It fails to detect system faults in time, thus causing heavy loss. To ensure their operations are at an ideal state, this work proposes an unsupervised method for intelligent performance evaluation and data-driven fault detection, which enables engineers to check PV panels in time and implement timely maintenance. It classifies monitoring data into three subsets: ideal period A, transition period S, and downturn period B. Based on A and B datasets, we build two non-continuous regression prediction models, which are based on a tree ensemble algorithm and then modified to fit the non-continuous characteristic of PV data. We compare real-time measured power with both upper and lower reference baselines derived from two predictive models. By calculating their threshold ranges, the proposed method achieves the instantaneous performance monitoring o... [more]

Scientific researchers have applied newly developed technologies, such as sensors and actuators, to different fields, including environmental monitoring, traffic management, and precision agriculture. Using agricultural technology to assist crop fertilization is an important research innovation that can not only reduce the workload of farmers, but also reduce resource waste and soil pollution. This paper describes the design and development of a water-fertilizer control system based on the soil conductivity threshold. The system uses a low-cost wireless sensor network as a data collection and transmission tool and transmits the data to the decision support system. The decision support system considers the change in soil electrical conductivity (EC) and moisture content to guide the application of water-fertilizer, and then improves the fertilization accuracy of the water-fertilizer control system. In the experiment, the proposed water-fertilizer control system was tested, and it was co... [more]

Ammonia is an important chemical raw material and the main hydrogen energy carrier. In the context of “carbon neutrality”, green ammonia produced using renewable energy is cleaner and produces less carbon than traditional ammonia production. Raw hydrogen dynamically fluctuates during green ammonia production because it is affected by the instability and intermittency of renewable energy; the green ammonia production process has frequent variable working conditions to take into account. Therefore, studying the transition state process of green ammonia is critical to the processing device’s stable operation. In this study, a natural gas ammonia production process was modified using green ammonia, and steady-state and dynamic models were established using UniSim. The model was calibrated using actual factory data to ensure the model’s reliability. Based on the steady-state model, hydrogen feed flow disturbance was added to the dynamic model to simulate the transition state process under v... [more]

In view of the working principle of a swashplate axial piston pump, a simulation model of the piston pump was built in AMESim and its output flow pulsation characteristics were simulated and analyzed. We mainly analyzed the influence of the speed of the prime mover, the swashplate angle, the diameter of the piston, and port plate structure on the flow pulsation of the piston pump. The result of this research shows that the port plate structure, the swashplate angle, and the speed of the prime mover have an important influence on the flow pulsation of the piston pump. In order to effectively reduce the flow pulsation generated by the piston pump and reduce the noise generated in the process of flow distribution, the opening of the pre-compression angle and misalignment angle of the port plate of the piston pump must be reduced appropriately and the swashplate angle and the rotation speed of the prime mover should be controlled within a certain range. The flow pulsation of the axial pist... [more]

To solve the dimensional explosion problem, this paper proposes a new architecture for the fuzzy system, the deep hierarchical self-organizing interval type-2 fuzzy system (DHSOIT2FS). Each sub-fuzzy system is a self-organizing interval type-2 fuzzy system, constructed online, with rules constructed by a rule online update algorithm, consequent parameters updated by iterative least squares, and antecedent parameters are updated using a gradient descent algorithm. DHSOIT2FS uses a classic serial-layered structure to build the overall framework. The first layer uses the first two dimensions of data as input. Each subsequent layer uses the output of the previous layer with the next dimensional data as input until it is built. During the training process, each data point is trained with DHSOIT2FS before passing in the next data point to achieve online construction. The effectiveness of the approach in this paper is illustrated using two numerical simulation examples. The proposed method is... [more]

The commutation failure of high voltage direct current (HVDC) systems could lead to unstable operation of the alternating current/direct current (AC/DC) hybrid power grid. The commutation voltage distortion caused by harmonics is a considerable but unclear factor of commutation failure. According to the control switching process of HVDC systems, the commutation voltage-time area method is employed to analyze and reveal the influence mechanism of harmonic components of commutation voltage on first and subsequent commutation failures. Considering the distortion characteristics of AC voltage, a predictive commutation failure suppression strategy considering multiple harmonics of commutation voltage is proposed. In this strategy, the new extinction angle and the zero-crossing offset angle after voltage distortion are calculated considering the harmonic components so as to obtain the compensation margin of the lag trigger angle by combining the correction margin with the voltage change rate... [more]

The interline power flow controller (IPFC) can control the active power and reactive power of different lines in power system. To utilize the flexible control ability of IPFC and increase the damping characteristic of its controller AC system, this paper proposes a low-frequency oscillation (LFO) suppress method through IPFC. The LFO suppress method is designed by adding supplementary signals to the outer current control loop of IPFC. In addition to adding supplementary active power signals, the reactive supplementary signals are also added to related control loop, which is the total control scheme. To obtain the power system’s small signal model, the identification technology based on the PRONY algorithm is used. In addition, the robust control theory is also applied to make the controllers more adaptive. To verify the effectiveness of the proposed method, two controllers including both the active and reactive controllers are designed for in PSCAD software. Furthermore, the simulation... [more]

Lyophilization is a widely used drying operation, but long processing times are a major drawback. Most lyophilization processes are conducted by a recipe that is not changed or optimized after implementation. With the regulatory demanded quality by design (QbD) approach, the process can be controlled inside an optimal range, ensuring safe process conditions. Process analytical technology (PAT) is crucial because it allows real-time monitoring and is part of a control strategy. In this work, emerging PAT (manometric temperature measurement (MTM), comparative pressure measurement, heat flux sensors, and ice ruler) are used for measurements during the freeze-drying process, and their potential for implementation inside a control strategy is outlined.

Two fluorescent dyes, alizarin red S (ARS) and calcein (CAL), were applied to evaluate the marking effects on the juveniles of Acanthopagrus schlegelii. The total mortality rates of the experimental groups were significantly lower (p < 0.05) than those of control groups, but no significant difference was detected between those of the two staining methods. The fluorescence microscopy observation results showed that the marking quality of ARS was better than that of CAL, with fin spines and fin rays being the best marking tissues. The optimal concentration for ARS and CAL was 200 mg/L and 350 mg/L, respectively. To ensure mark quality, the recommended dye grade was above 3, and the most suitable marking conditions were suggested to be fluorescence labeling with ARS dye at a concentration of 200 mg/L, with immersion for 24 h. The results will provide useful data information for future research on stock enhancement using the chemical marking method.

There are unfavorable conditions such as constantly changing working conditions and frequent disturbances that affect Mach number control in wind tunnel flow fields. As the proportional, integral and differential (PID) parameters need to be re-tuned for each working conditions of a wind tunnel, the operational costs of wind tunnels are very high. Therefore, to lower these costs, a genetic algorithm was utilized to tune the PID parameters to achieve Mach number control of a multi-mode wind tunnel flow field. In this paper, firstly, models for the multi-mode wind tunnel were established; secondly, a PID control system was designed based on the genetic algorithm and the control effects of the proposed PID control system were verified by simulations and were compared with the effects of a PSO tuning PID control system.

An unreasonable allocation of resources has led to a low rate of output in the industry−university−research collaboration network. A solution to this problem is to control and predict the input and output. However, the network has the characteristics of strong nonlinearity and insufficient samples. It is difficult for the existing control methods to migrate to collaboration networks because the traditional control methods, including Proportional−Integral−Derivative (PID) control and Model Predictive Control (MPC), are usually not applied to the system with strong nonlinearity and the controlled system needs to have specific parameters, while the modern control methods, including feedforward control and feedback control, have their limitations in both parameters and other aspects. In addition, there is a lack of research on the control and output prediction of collaboration networks, and there is no effective and applicable scheme for the control and prediction. Considering the nonlinea... [more]

The digital transformation of the logistics industry is the current trend of development. In order to promote the integrated development of the logistics industry (LI) and the digital economy (DE), we propose a data-driven method which can be used to measure, evaluate, and identify the coupled and coordinated development (CCD) of the LI and DE. On the basis of data collection, we use the entropy weight method to measure the comprehensive development level of the LI and DE. A coordination model is then used to evaluate their CCD level. Finally, an obstacle degree model (ODM) is used to identify the key factors inhibiting the coordinated development (CD) of the two. This method is then applied to gauge the integration development of the LI and DE in Anhui Province. The results show that energy consumption and the lack of logistics employees are the main obstacles to the development of the LI in Anhui Province. The main obstacles to the development of the DE are the low development level... [more]

This study proposes a recognition method based on symmetrized dot pattern (SDP) analysis and convolutional neural network (CNN) for rapid and accurate diagnosis of insulation defect problems by detecting the partial discharge (PD) signals of XLPE power cables. First, a normal and three power cable models with different insulation defects are built. The PD signals resulting from power cable insulation defects are measured. The frequency and amplitude variations of PD signals from different defects are reflected by comprehensible images using the proposed SDP analysis method. The features of different power cable defects are presented. Finally, the feature image is trained and identified by CNN to achieve a power cable insulation fault diagnosis system. The experimental results show that the proposed method could accurately diagnose the fault types of power cable insulation defects with a recognition accuracy of 98%. The proposed method is characterized by a short detection time and high... [more]

In order to solve the problem that the fault classification accuracy of the main bearing of the wind turbine is not high due to the unbalanced vibration signal data of the main bearing of the wind turbine under the background of noise, this article proposes a double-layer fault diagnosis model for the main bearing of the wind turbine that combines the auxiliary classifier generation adversarial network (ACGAN) and the deep residual shrinkage network (DRSN). First, the wind turbine main bearing data is sent into the ACGAN to learn the distribution features of fault data, and a particular type of fault data is generated to expand the original dataset to achieve balance conditions, and then the expanded dataset is sent to the DRSN to reduce noise to improve the fault classification accuracy. The simulation results show that, compared with the traditional deep learning model, the model proposed in this article can significantly improve the classification accuracy of the main bearing fault... [more]

The proportion of the coal and rock masses in different areas of surrounding rocks is quite different when a large-section coal roadway is excavated in gently inclined soft coal seams. Different creep failure occurs in coal and rock masses under high stress, which results in uneven deformations of roadways and difficulties in maintenance. This work studied the belt grooves of the 2103 working face in the lower coal group of the Wulihou Coal Mine. Theoretical analysis and measured geomechanical evaluation were used to analyze the failure causes of the surrounding rocks of the roadway. The failure law of large-section roadways in the gently inclined soft coal seams was studied using finite-difference numerical simulation software. Combined with the results of mathematical analysis, surrounding rocks were divided into regions. Surrounding-rock control schemes for different areas, such as grouting reinforcement, strengthening support, and pressure-relief grooving, were proposed separately... [more]

From the outset of the war in Ukraine, extensive crises in many sectors of the world economy have occurred, with firms offering services and products both online and through physical stores facing serious problems. These problems are mainly related to higher operational costs and the lack of website visibility. For this research study, centralized payment network organizations (CPNs), firms providing online payment services through their networks, were selected and analytical data from their websites were collected for a period of 6 months. The main focus of this research study is to evaluate benefits and the role of social media strategies for CPNs’ digital marketing performance during crisis events and to also assess their utility as a risk-management tool. Following data collection, the authors performed statistical processes (regression and correlation analysis) and stationary modeling with Fuzzy Cognitive Mapping (FCM) tools; finally, dynamic simulations were performed by utilizin... [more]

In a regenerative aluminum smelting furnace, real-time liquid aluminum temperature measurements are essential for process control. However, it is often very expensive to achieve accurate temperature measurements. To address this issue, a just-in-time learning-based triple-weighted regularized extreme learning machine (JITL-TWRELM) soft sensor modeling method is proposed for liquid aluminum temperature prediction. In this method, a weighted JITL method (WJITL) is adopted for updating the online local models to deal with the process time-varying problem. Moreover, a regularized extreme learning machine model considering both the sample similarities and the variable correlations was established as the local modeling method. The effectiveness of the proposed method is demonstrated in an industrial aluminum smelting process. The results show that the proposed method can meet the requirements of prediction accuracy of the regenerative aluminum smelting furnace.

The quality-control process in manufacturing must ensure the product is free of defects and performs according to the customer’s expectations. Maintaining the quality of a firm’s products at the highest level is very important for keeping an edge over the competition. To maintain and enhance the quality of their products, manufacturers invest a lot of resources in quality control and quality assurance. During the assembly line, parts will arrive at a constant interval for assembly. The quality criteria must first be met before the parts are sent to the assembly line where the parts and subparts are assembled to get the final product. Once the product has been assembled, it is again inspected and tested before it is delivered to the customer. Because manufacturers are mostly focused on visual quality inspection, there can be bottlenecks before and after assembly. The manufacturer may suffer a loss if the assembly line is slowed down by this bottleneck. To improve quality, state-of-the-a... [more]

This paper studies the dynamic formation control of second-order multi-agent systems (MASs) in three-dimensional space based on the distance control approach. A rigid graph represents the communication topology between agents to improve the system’s robustness and stability and avoid collisions and deformations during formation operation. A distributed control strategy based on the relative states among neighbors is designed for each agent to achieve formation and formation maintenance under arbitrary initial conditions. The Lyapunov function, an error function of potential and kinetic energy, is constructed by rigid graph theory and a second-order integrator model. The decreasing of the Lyapunov function is proven by Barbalat’s theory, further indicating that the system is asymptotically stable. A second-order MAS composed of nine agents is constructed, and the dynamic scaling of rigid formations in 3D space is achieved through simulation to verify the effectiveness of the controller... [more]

Control cables transfer force between two separate locations by a flexible mean, and hence, they are important in the automotive industry and many others; their terminals interact with both moving and moved mechanisms, so they must be strong. Cable terminals are commonly made of ZAMAK and are created by injection molding. However, such a production method requires leaving extra material to allow the correct molding, also known as sprues, which are removed later in the process. In this case, the sprues were separating from the terminals in an uncontrolled way. In this work, the cause of sprues separating prematurely from the terminals in a production line is addressed. The whole process was analyzed, and each possible solution was evaluated using process improvement techniques and the Finite Element Method, leading to the best solutions. Molds, mold structures, and auxiliary equipment were improved, resulting in a minimally invasive intervention and remaining compatible with other equip... [more]

Reagent addition is an important operation in the froth flotation process. In most plants, it is manually regulated according to the operator’s experience, by observing the surface features of the froth. Due to the drawbacks of manual operation, large fluctuations in the process are common, resulting in unexpected process indexes. Thus, we investigated the relationship between reagent addition, feed conditions (including ore properties, slurry density, and slurry flow rate), and froth image features based on the mechanism of froth flotation and production technology of gold-antimony flotation. Then, we proposed a two-step optimal-setting control strategy for reagent addition, which included a basic dosage pre-setting model and a feedback reagent addition compensation model. According to operating conditions and ore properties, the pre-setting model was developed using a belief rule base (BRB) method based on an evidential reasoning approach (RIMER), which could effectively address the... [more]

The high-performance control technology of multi-phase motors is a key technology for the application of multi-phase motors in many fields, such as electric transportation. The model predictive current control (MPCC) strategy has been extended to multi-phase systems due to its high dynamic performance. Model-predictive current control faces the problem that it cannot effectively regulate harmonic plane currents, and thus cannot obtain high-quality current waveforms because only one switching state is applied in a sampling period. To solve this problem, this paper uses the virtual vector-based MPCC to select the optimal virtual vector and apply it under the premise that the average value of the harmonic plane voltage in a single switching cycle is zero. Taking a five-phase induction motor as an example, the steady-state and dynamic performance of the proposed virtual vector MPCC and the traditional model predictive current control were simulated, respectively. Simulation results demonst... [more]

Sensor acquired signal has been a fundamental measure in rotary machinery condition monitoring (CM) to enhance system reliability and stability. Inappropriate sensor mounting can lead to loss of fault-related information and generate false alarms in industrial systems. To ensure reliable system operation, in this paper we investigate a system’s multiple degrees-of-freedom (DOF) using the finite element method (FEM) to find the optimum sensor mounting position. An appropriate sensor position is obtained by the highest degree of deformation in FEM modal analysis. The effectiveness of the proper sensor mounting position was compared with two other sensor mounting points, which were selected arbitrarily. To validate the effectiveness of this method we considered a gear-actuator test bench, where the sensors were mounted in the same place as the FEM simulation. Vibration data were acquired through these sensors for different health states of the system and failure patterns were recognized u... [more]

The Lamadian oilfield has entered the stage of strong water cut after natural energy development and conventional water flooding development. The use of asphalt binder for profile control can not only adjust the contradiction between layers, expand the swept volume, but also improve the oil displacement efficiency. The field test has achieved certain results. The main oil layer in the Lamadian oilfield has a strong oil layer thickness and serious vertical and plane heterogeneity. After years of water injection development and polymer injection development, most oilfields have entered a period of strong water cut. In the test, it is found that the effect of different well layers is very different, the effect is unstable, and the reason is unclear. Therefore, it is necessary to carry out research on the adaptability and parameter optimization of profile control of asphalt binder through laboratory experiments. In this paper, the asphalt binder provided on site are modified and the disper... [more]