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The advancement of capital market to a more mature stage is shown in the construction of the securities issurance registration system. ChiNext announced the registration system reform in June 2020, which has helped ChiNext make significant strides and attracted investors' attention. The DID Model will be used in this study to assess the effects of the registration system reform on the volatility over the past four years for Shenzhen Component Index and ChiNext Index. At the same time, linear regression was used to verify the validity of the Fama-French three-factor model on ChiNext yield in recent four years. The results show that the introduction of the registration system increases the volatility of ChiNext yield; In ChiNext market, the ability of the Fama-French three-factor model to predict the yield has declined slightly after the implementation of the registration system, while the market risk premium factor is highly significant, and the model still has the predictability of returns.

This article presents a control strategy to improve the energy efficiency of a quadrotor for field inspections. A power consumption analytical model for a quadrotor is constructed, which indicates that the power consumption of a quadrotor is correlated with the roll and pitch angles. Based on that, a cascaded bounded control framework is developed to regulate the roll and pitch angles within the predefined energy-efficient ranges, while a successful inspection trajectory tracking can be achieved simultaneously. Experimental studies are carried out to prove the effectiveness of the proposed method through a mock-up scenario of wind farm inspection. Compared to the conventional cascaded control framework, the proposed energy saving control strategy is capable of saving 5% energy for the same inspection assignment under wind disturbance.

In order to improve the dynamic performance of the sensorless permanent magnet synchronous motor drive system, the modified pulsating high frequency voltage injection method is proposed. Firstly, the second order generalized integrator can be used to extract the high frequency voltage signal instead of band-pass filters. The specific frequency harmonic elimination unit is applied to obtain the rotor position error signal to avoid using the low-pass filter. Therefore, the system dynamic performance can be improved. In addition, the system parameter is easier to adjust than traditional methods with band-pass filters and low-pass filters. Finally, the simulation model and experimental platform are built to verify the effectiveness of the proposed method. The simulation and experimental results present that the dynamic performance of motor drive system can be improved.

Small-diameter tissue-engineered vascular grafts (sdTEVGs) with hyperglycemia resistance have not been constructed. The intimal hyperplasia caused by hyperglycemia remains problem to hinder the patency of sdTEVGs. Here, inspired by bionic regulation of nerve on vascular, we found the released neural exosomes could inhibit the abnormal phenotype transformation of vascular smooth muscle cells (VSMCs). The transformation was a prime culprit causing the intimal hyperplasia of sdTEVGs. To address this concern, sdTEVGs were modified with an on-demand programmable dual-responsive system of ultrathin hydrogels. An external primary Reactive Oxygen Species (ROS)-responsive Netrin-1 system was initially triggered by local inflammation to induce nerve remolding of the sdTEVGs overcoming the difficulty of nerve regeneration under hyperglycemia. Then, the internal secondary ATP-responsive DENND1A (guanine nucleotide exchange factor) system was turned on by the neurotransmitter ATP from the immigrated nerve fibers to stimulate effective release of neural exosomes. The results showed nerve fibers grow into the sdTEVGs in diabetic rats 30 days after transplantation. At day 90, the abnormal VSMCs phenotype was not detected in the sdTEVGs, which maintained long-time patency without intima hyperplasia. Our study provides new insights to construct vascular grafts resisting hyperglycemia damage., Graphical abstract Image 1, Highlights • VSMCs undergo a phenotypic transformation under high glucose, which lead to intimal hyperplasia in sdTEVGs. • Neural exosomes could inhibit the abnormal phenotype transformation of VSMCs from contractile to synthetic. • SdTEVGs with on-demand programmable dual responsive system inhibited intimal hyperplasia in diabetes.

The high-speed maglev train based on the doubly-fed linear motor (DFLM) has the potential advantages to achieve suspension, traction, and contactless power transfer simultaneously, which improves the reliability of the maglev system and system cost. However, there is still a lack of relevant designs of the doubly-fed linear motor to meet critical requirements for practical high-speed maglev applications, e.g., the low fluctuations of the levitation and thrust forces. In this paper, based on the performance of the German TR08 maglev train, finite element analysis (FEA) technology is used to investigate the effects of different pole-slot combinations and multi-phase winding structures on the suspension force and thrust force of the doubly-fed linear motor. A doubly-fed linear motor topology based on 36-slot 12-pole three-phase stator and 20-slot 12-pole five-phase mover is proposed, which can greatly reduce the fluctuations of suspension and thrust forces, and its performance is close to the level of TR08 maglev train. Finally, the performance of the contactless power transfer for the DFLM is analyzed.

In this brief, a bounded integral controller (BIC) with limited control power is proposed for a class of nonlinear multiple-input multiple-output (MIMO) systems. The sum-of-squares constraint on the control inputs with time-varying weights is studied and handled through the BIC design, which guarantees that both the control inputs and an auxiliary time-varying variable are dynamically constrained on a designed control circle. The BIC inherits the properties of the traditional integral controller to eliminate tracking errors and achieve disturbance rejections. Even under time-varying input weights, the BIC guarantees limited control power independently of both plant information and system states. The input-to-state (practical) stability of the closed-loop system is established. To demonstrate the effectiveness of the proposed method, experimental validations are conducted for two systems: a system with multiple dc motors subject to a power limit with time-varying input weights and a permanent magnet synchronous motor system subject to a voltage limit with time-invariant input weights.

The uncertainty and disturbance estimator (UDE)-based controller has emerged as an effective robust control method to handle systems with uncertainties and disturbances. However, similar to other controllers including an integral action, the UDE-based controller faces the integral windup issue when the system has input constraints. In this article, a bounded UDE-based controller is proposed to deal with systems subject to uncertainties, disturbances, and input constraint. An additional time-varying variable is introduced into the design of the error dynamics to naturally avoid integral windup. The boundedness design guarantees that both the final controller output and the additional time-varying variable dynamically move on an ellipse so that the controller output always satisfies the input constraint. The proposed bounded UDE-based controller inherits the robustness of the conventional UDE-based control method, and has a clear structure, with guidelines provided for parameter selections. Both theoretical analysis and experimental results are provided to validate the proposed design.

In this paper, a quasi-synchronization operation of a doubly-fed linear motor is proposed to achieve accurate regulation of both the traction and the contactless power transfer. A new control structure is proposed to achieve the loose coupling control between the stator side and the mover side, where the scalar control is used for the stator side controller (SSC), and the field-oriented control (FOC) is adopted for the mover side controller (MSC). The SSC and the MSC is with “frequency-coupling”, which enhances the reliability of the whole control system with less information exchange between the SSC and the MSC. The effectiveness of the proposed design is validated through both simulation and experimental studies.

Carbon fiber reinforced plastic (CFRP) composites were attractive in lots of applications, in which surface machining processes were always needed after molding fabrication processes to achieve the final functional surface geometry with desired accuracy. To improve the effectiveness and efficiency, rotary ultrasonic surface machining (RUSM) had been applied in processing CFRP composites. With the assistance of vertical ultrasonic vibration in RUSM, cutting forces were significantly reduced, but the surface roughness was increased. To improve the surface conditions and additionally reduce the cutting force for RUSM, the applied ultrasonic vibration should be aligned with surface generation direction (namely horizontal feeding direction). Up till now, there were no reported investigations on RUSM with horizontal vibration and 3D elliptical ultrasonic vibration, formed from the combination of horizontal and vertical ultrasonic vibrations. In this investigation, the horizontal and 3D elliptical ultrasonic vibrations were applied in RUSM. The comparisons among RUSM with 3D elliptical ultrasonic vibration, RUSM with horizontal ultrasonic vibration, and the surface machining without ultrasonic vibration on machining performance and surface quality were conducted. Experimental results showed that RUSM with horizontal ultrasonic vibration reduced both cutting force and surface roughness. With the application of 3D elliptical ultrasonic vibration, both cutting force and surface roughness can be further decreased. The critical horizontal ultrasonic frequency for the overlapping of abrasive grains’ trajectories was analyzed. The mechanisms of RUSM with both horizontal and 3D elliptical ultrasonic vibrations and the reasons for both cutting force decreasing and surface roughness decreasing were also investigated.

Control and power electronics are two major enablers for the paradigm shift of power systems from centralized generation to distributed generation, the electrification of transportation, and the transformation of billions of lives in third-world countries. Experimental validations of control algorithms for these systems play a vital role. However, setting up a suitable experimental system requires time, effort, and a broad range of expertise. This demonstration session aims to help researchers, graduate students, and engineers remove the barriers to go real from simulations to experiments for various power electronic-based systems. It shows that it is possible to obtain experimental results within hours after completing simulations by adopting the SYNDEM Smart Grid Research and Educational Kit, which is a reconfigurable, open-source, multifunctional power electronic converter with the capability of directly downloading codes from Matlab/Simulink. This will maximize the strengths of the control community in developing control algorithms, minimize the efforts on developing hardware systems and programming control algorithms, and improve the efficiency and productivity of research and learning.

The energy flow is step-by-step among Lithium-ion-battery when an equalizer based on the buck-boost converter is adopted, resulting in a long energy transmission path and low equalization efficiency. First, a Lithium-ion-battery equalizer based on the dual active half-bridge is studied in this paper. Second, the key parameters of the energy flow between cells in the same group and cells in different groups in the equalizer are analyzed. Third, a phase shift control strategy is put forward according to the analysis results. The equalizer with the proposed control strategy not only can realize the energy flow between cells in the same group and different groups but also work at high frequency. Therefore, the transformer can be designed to be small in size and light in weight, greatly reducing the volume and weight of the equalizer. A prototype of the dual active half-bridge equalizer with four lithium batteries was managed. The experimental results show that the proposed Lithium-ion-battery equalizer based on phase shift control has good equalization performances.

Power systems are going through a paradigm shift. More and more distributed energy resources (DERs) and loads are being connected to power systems, mostly through power electronic converters. These power electronic converters can be controlled as virtual synchronous machines (VSMs), leading to a unified interface for grid integration. As a result, all active players in a power system can take part in the regulation of system frequency and voltage in a synchronized and democratized (SYNDEM) manner, significantly simplifying system operation and improving grid stability, reliability, resiliency, security, and sustainability. This article presents a pilot smart home grid at the Llano River Field Station, Texas Tech University Center at Junction, that is built according to the SYNDEM grid architecture. The home grid consists of five DER units, including four 3-kW solar units and one 3-kW wind unit with built-in battery storage in each unit, and one energy bridge for grid connection. The energy bridge has two VSMs connected back-to-back with a common dc bus. All the units are equipped with a self-synchronized universal droop controller (SUDC) with many advanced functions, i.e., black-start, grid-forming, self-synchronization without a phase-locked-loop (PLL), voltage and frequency regulation, power sharing, and power quality control. The home grid can work with or without the public grid, with seamless mode change between grid-tied operation and islanded operation. All the functions are achieved without using a communication network; hence, potential cyberattacks can be avoided. Field operation results of the home grid are presented to demonstrate the autonomous operation of the system.

Although the polysaccharide utilization loci (PULs) activated by pectin have been defined, due to the complex of side-chain structure, the degradative mechanisms still remain vague. Thus, we hypothesize that there may have other specific PULs to target pectin. Here, we characterize loci-encoded proteins expressed by Bacteroides thetaiotaomicron (BT) that are involved in the pectin capturing, importation, de-branching and degradation into monosaccharides. Totally, four PULs contain ten enzymes and four glycan binding proteins which including a novel surface enzyme and a surface glycan binding protein are identified. Notably, PUL2 and PUL3 have not been reported so far. Further, we show that the degradation products support the growth of other Bacteroides spp. and probiotics. In addition, genes involved in this process are conservative in other Bacteroides spp. Our results further highlight the contribution of Bacteroides spp. to metabolism the pectic network.

The effects of nitrification inhibitor in tea gardens with different urea&ndash, N rates have rarely been assessed. For eight months, a glasshouse experiment was conducted to investigate the effects of a nitrification inhibitor (3, 4&ndash, dimethylpyrazole phosphate, DMPP) on the changes of soil pH and inorganic N loss. Urea (0, 300, 500, and 800 kg N ha&minus, 1) with or without DMPP (1% of urea&ndash, N applied) were added to pots that hosted six plants that were three years old. Next, three leaching events were conducted with 600 mL of water after 7, 35, and 71 days of intervention while soil samples were collected to determine pH and inorganic N. Averaged across sampling dates, urea&ndash, N application at an increasing rate reduced soil pH with the lowest values at 800 kg urea&ndash, N ha&minus, 1. Adding DMPP increased soil pH up to a rate of 500 kg ha&minus, 1. Irrespective of the addition of DMPP, gradient urea&ndash, N application increased the leaching loss of inorganic N. On overage, DMPP increased soil pH and decreased leaching losses of total inorganic N, suggesting a higher soil N retention. Therefore, we believe that this increase in soil pH is associated with a relatively lower proton release from the reduced nitrification in the DMPP&ndash, receiving pots. This nitrification reduction also contributed to the N loss reduction (NO3&minus, &ndash, N). Altogether, our results suggest that DMPP can reduce N leaching loss while maintaining the pH of tea&ndash, cultivated soils. Therefore, DMPP application has a significant potential for the sustainable N management of tea gardens.

The open-winding topology with common dc bus is applied to permanent magnet brushless motor for promoting power density and elevating torque output capacity, however zero-sequence current will be generated in the winding which would reduce the efficiency and system stability. Therefore, a kind of decoupled space vector pulse width modulation strategy is proposed in this paper which can eliminate the common mode voltage to suppress the zero-sequence current. In addition, the utilization of dc link voltage can be improved effectively. Finally, the experimental platform is built and the proposed control strategy is verified by the experimental results.

The uncertainty and disturbance estimator (UDE)-based robust control has a two-degree-of-freedom nature through the design of the error dynamics and the design of the UDE filters. In the conventional design to handle periodic disturbances or mixed sinusoidal disturbances, high-order UDE filters incorporated with the internal model principle (IMP) or time-delay filters (TDF) are adopted to achieve the asymptotic reference tracking and the asymptotic disturbance rejection. In this paper, a new error dynamics design combined with a repetitive loop is proposed for the UDE-based robust control to achieve the asymptotic rejection of both step disturbances and periodic disturbances. The disturbance rejection performance is investigated through the two-degree-of-freedom nature, and the practical implementation of the proposed design is illustrated to eliminate the infinite bandwidth of the repetitive loop. The proposed design is validated through the simulation studies of a battery charging system with comparison to different reported designs of the conventional UDE-based robust control.

The only constant is change-power systems worldwide are going through a paradigm change from centralized generation to distributed generation; transportation systems are being electrified; and billions of lives in third-world countries are awaiting low-cost sustainable electricity. Control and power electronic technologies are two common enablers to address these grand challenges. Empowering next-generation engineers with hands-on skills in control and power electronics has become a priority for global higher education. However, setting up a suitable experimental system requires time, effort, and a broad range of expertise. This article aims to help researchers, university professors, graduate students, and engineers lower the barriers to go real from simulations to experiments for various power electronic systems and improve the efficiency and productivity of research, development, and education. It shows that it is possible to obtain experimental results within hours after completing simulations by adopting the SYNDEM Smart Grid Research and Educational Kit, which is a reconfigurable, opensource, multifunctional power electronic converter with the capability of directly downloading codes from MATLAB/Simulink. This minimizes the time, cost, and efforts needed to develop hardware systems and removes the burden of coding. After briefly introducing the SYNDEM kit and highlighting the automatic code generation capability, two case studies will be illustrated: an ac motor drive and a dc-dc-ac converter for an integrated PV-storage system.

For achieving higher energy transferring efficiency from the resources to the load, the Combined Cooling, Heating, and Power (CCHP) systems have been widely researched and applied as an efficient approach. The key idea of this study is designing a novel structure of a hybrid CCHP system and evaluating its performance. In this research, there is a hybrid energy storage unit enhancing the whole system’s operation flexibility while supplying cooling, heating, and power. An ORC system is integrated into the CCHP system which takes responsibility of absorbing the low-temperature heat source for electricity generation. There are a few research studies focusing on the CCHP systems’ performance with this structure. In order to evaluate the integrated system’s performance, investigation and optimisation work has been conducted with the approaches of experimental studies and modelling simulation. The integrated system’s configuration, the model building process of several key components, the optimisation method, and the case studies are discussed and analysed in this study. The design of the integrated system and the control strategy are displayed in detail. Several sets of dynamic energy demand profiles are selected to evaluate the performance of the integrated system. The simulation study of the system supplying selected scenarios of loads is conducted. A comprehensive evaluation report indicates that the system’s efficiency during each study process differs while supplying different loads. The results include the power supplied by each component, the energy consumed by each type of load, and the efficiency improvements. It is found that the integrated system fully satisfies the selected domestic loads and various selected scenarios of loads with high efficiency. Compared to conventional power plants or CHP systems, the system efficiency enhancement comes from higher amount of recovery waste heat. Especially, the ORC system can absorb the low-temperature heat source for electricity generation. Compared to the original following electrical load (FEL) control strategy, the optimisation process brings overall efficiency improvements. The system’s overall efficiency was increased by from 3%, 3.18%, 2.85%, 17.11%, 8.89%, and 21.7% in the second case studies. Through the whole study, the main challenge lies within the design and the energy management of the integrated system.

Compared to a long-stator linear synchronous motor (LLSM), a long-stator doubly-fed linear motor (DFLM) exhibits two distinct advantages for high-speed maglev application: 1) It has two additional degrees of freedom with both the frequency and the phase angle of the mover to improve its control accuracy and dynamic responses; 2) It can use the slip power to feed the mover contactlessly and directly. In order to achieve the propulsion, the levitation, and the contactless power transfer through the common air-gap magnetic field, the “quasi-synchronous operation (QSO)” principle of the DFLM is proposed for high-speed maglev train. Based on the DFLM modeling and distinctive constraints for maglev train, the operation point analysis of the performance evaluation is further investigated. To validate the feasibility of the DFLM application for high-speed maglev train, a unit DFLM prototype is designed and tested, and the corresponding simulation studies of the QSO control structure are investigated.

An energy optimization control strategy for the Hybrid Electric Vehicle (HEV) is developed in this paper to reduce the fuel consumption, on the premise of the operation demand, which makes the engine and motor working in the high efficiency operation area. The energy management model of Pontryagin's Minimum Principle (PMP) for the parallel hybrid vehicle is set up, the state of charge (SOC) and the output power of the battery are chosen as the state variable and control variable, respectively. The total fuel consumption during the HEV operation is considered as the objective function, and PMP is used to obtain the optimum solution. The simulation results verify the effectiveness of the developed control strategy, with which the higher output torque of the engine and the lower output torque and higher efficiency of the motor are achieved compared with the energy management strategy based on logic rule. Moreover, the 100-kilometer fuel consumption is reduced by 40%, and the fuel economy is greatly improved.

Fuel economy is pursued by hybrid electric bus (HEB). However, a key challenge for a hybrid bus is to achieve near-optimality while keeping the energy management strategy (EMS) simple. In this paper, an EMS based on the Pontryagin’s minimum principle (PMP) is developed and implemented in ADVISOR. The designed EMS can successfully calculate the fuel consumption of the parallel HEB under the specific driving cycle. The simulation result suggests that the fuel economy of the hybrid electric bus with PMP-based control strategy is close to the benchmarking optimal solution calculated through DP, which is much better than the fuel economy of the parallel HEB with the default control strategy in ADVISOR. To sum up, the EMS based on PMP can improve the fuel economy by adjusting the engine operating point to reduce the exhaust emissions. Simultaneously, it can also extend the battery life by maintaining the battery state of charge at an appropriate level.

The flux-switching permanent-magnet double-rotor machine (FSPM-DRM) used for hybrid electric vehicles has attracted considerable attention due to the compact structure and high torque density. Compared with conventional machine, the FSPM-DRM suffers from more severe thermal problems in its inner rotor. This paper aims to make an accurate prediction of the performances and temperature distributions in the FSPM-DRM. First, the eddy current loss in windings with an improved analytical method is discussed and the results are validated by those from a 2-D finite-element (FE) model. With the obtained power losses, the lumped-parameter scheme considering end effect is compared with a 3-D FE thermal model to predict the temperature in each part of the FSPM-DRM at hybrid driving mode, in which both yield similar results. Then the maximum temperatures of different parts at the rated load and 160% load under various operational modes are simulated. Some experimental results are reported, validating the numerical and simulated results.