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To enhance adaptability in orchards with taller average tree heights and improve spraying effectiveness on Jinggang pomelo trees, this paper proposes a UAV-UGV cooperative targeted spraying system (UCTSS) and develops a prototype. The UCTSS primarily consists of a UAV and a UGV, networked using the Robot Operating System (ROS). During operation, both the UAV and UGV navigate between tree rows while carrying the spraying module. When the UAV reaches suitable spraying positions, the UGV halts to activate the spraying module, and the UAV performs targeted spraying from top to bottom. The paper employs a master-slave method for basic formation control of the UAV and UGV, resulting in an average tracking error of 0.118 m and a standard deviation of 0.040 m during testing. Additionally, a LiDAR-based targeted spraying detection method is designed and validated through simulation experiments, achieving an accuracy rate of 96% with an average position error of 0.13 m. Field trials in orchards demonstrate that the UCTSS meets stability requirements, with the average tracking error of the UAV measuring 0.158 m during coordinated movement and 0.013 m during spraying. In terms of spraying effectiveness, the UCTSS exhibits higher average droplet density and deposition values at various heights of the same tree compared to the DJI-T50, along with a lower coefficient of variation between levels, resulting in a more uniform spraying effect. The feasibility of the UCTSS is validated, providing a novel approach for orchard protection in areas with taller average tree heights. [ABSTRACT FROM AUTHOR]

The possibility of transferring the sense and force of the user on the driver side to the follower robot has always been discussed in master/slave systems. It has gained special importance in recent research. In the present study, the control torque of the slave side is adjusted by transferring the user's force (with the haptic handle) from the master side to the slave robot. The proposed system is a four-channel approach where the position signal and force signal are transmitted to the slave on the master's side, and reciprocally, the position signal and the contact force of the environment on the slave reach the master's side. The input-to-state stability for the master-slave system is investigated with the proposed approach. The approach of this research, unlike the approach of many previous studies, does not require the acceleration of the joints to parameterize the robot's dynamics or control it. In this method, the amount of force/torque of the user's hand of the master robot will be directly involved in the control command of the slave robot. In this article, in addition to the four-channel system, a three-channel system is proposed. Both systems, in addition to following the path, can follow the user's will on the master's side when encountering unexpected obstacles and stopping joints. In addition to software simulation, experimental implementation has been done on a leader-follower system with haptic robots, which confirms the correctness of the proposed approach.

The paper analyses the possibilities of reinterpreting the novel The White Castle by situating it within the historical context. The setting of the novel antedates a period in the history of Turkey which is obfuscated from its secular and modern present. It is not random that the fictional historian Darvinoglu, at a period of political instability in Turkey, chooses a dumped manuscript from the governor's office in Gebze and publishes it. Ottoman history presents a spectrum of combats; from territorial warfares to political and religious conflicts and infightings. Darvinoglu is searching for a certitude and a fictional relief from the Republican unassuredness, by clinging to the monolithic empire in the past. The study explores the layers of interactions and hierarchies in the novel and explains how the sultanate nullifies these differences and preserves its integration for centuries. [ABSTRACT FROM AUTHOR]

The possibility of transferring the sense and force of the user on the driver side to the follower robot has always been discussed in master/slave systems. It has gained special importance in recent research. In the present study, the control torque of the slave side is adjusted by transferring the user's force (with the haptic handle) from the master side to the slave robot. The proposed system is a four-channel approach where the position signal and force signal are transmitted to the slave on the master's side, and reciprocally, the position signal and the contact force of the environment on the slave reach the master's side. The input-to-state stability for the master-slave system is investigated with the proposed approach. The approach of this research, unlike the approach of many previous studies, does not require the acceleration of the joints to parameterize the robot's dynamics or control it. In this method, the amount of force/torque of the user's hand of the master robot will be directly involved in the control command of the slave robot. In this article, in addition to the four-channel system, a three-channel system is proposed. Both systems, in addition to following the path, can follow the user's will on the master's side when encountering unexpected obstacles and stopping joints. In addition to software simulation, experimental implementation has been done on a leader-follower system with haptic robots, which confirms the correctness of the proposed approach. [ABSTRACT FROM AUTHOR]

Parallel inverters are commonly used for connecting photovoltaic (PV) and other renewable energy sources to Microgrids (MGs). One of the greatest challenges in MG operation is maximizing the PV system's performance while also enhancing the MG's reliability and efficiency. The PV inverters waste power if the shared load power is less than their maximum output power. When shared load power surpasses the PV inverter's maximum output power, the system may become unstable since PV sources are intermittent. This study proposes a master-slave control system for controlling parallel inverters connected to a PV system. The master inverter is connected to Energy Storage Devices (ESDs) and is responsible for maintaining stable voltage on the load bus. The PV units are connected via slave inverters and are managed using a dual-loop Proportional Integrator Derivative (PID) control approach, with the outer loop maximizing solar panel output. The system is built on a Direct-Quadrature-Zero (d-q-0) inverter architecture, and the controller guarantees that all inverter currents remain in phase to reduce circulating current and enhance overall system efficiency. The simulation model evaluates a system comprising three inverters, with the master inverter powered by ESDs. The PV Units power the other two Slave Inverters. The system is evaluated using four case studies featuring various load and radiation change scenarios. The results demonstrate that the system is highly reliable and operationally efficient, with the absence of circulating currents among the inverters. Moreover, the system is capable of precisely monitoring the MPPs of PV modules with 100% efficiency and a minimal 0.002% fluctuation, while also responding to changes in under 50 ms.

A Fixed-Switching-Frequency Model Predictive Control (FSF-MPC) for Master-Slave inverters in microgrids is proposed in this paper. The Master is a three-phase, two-level inverter with an LC filter, while the Slave is a three-phase, two-level inverter with an LCL filter. The inverters are connected in parallel in a microgrid, composed of different loads. The voltage and current inner control loops of the Master-Slave FSF-MPC are presented for both inverters. Then, two modes of operation are proposed: grid-connected and islanded, and the primary control for both cases is developed. Finally, Hardware-in-the-Loop (HIL) results are presented for different operational conditions of the microgrid with load-related disturbances. The HIL results validate the good performance of the proposed Master-Slave FSF-MPC, including fast dynamic response, multi-objective control, and fixed switching frequency.

Summary: With the advancement of power electronic converters over the last few decades, the capability to integrate solar photovoltaics, wind, diesel generators, batteries, ultracapacitor, and electric vehicles with standalone networks or utility grids has increased. For the reliable operation of standalone networks, accurate load sharing among these sources is required. As a result, several load sharing schemes with inherent merits and related demerits are presented in the literature. This work intends to address shortcomings of earlier reported control schemes with the inheritance of associated merits using the proposed control scheme. The proposed enhanced Master–Slave control, with advanced droop control scheme, is illustrated for Master voltage source inverter with resistive line impedance and improves the steady‐state response by improving voltage and frequency profile. It reduces the voltage drop caused by load effect and droop effect, allowing the voltage and frequency regulation during load changes and distinct load conditions such as balanced linear load, unbalanced linear load, and balanced nonlinear load in standalone alternating current (AC) microgrids. Furthermore, Slave voltage source inverters independently compensate for local load demand. This paper presents precise current control and voltage control design methodology and a mathematical model for voltage control and their performance analysis in time and frequency domain. Finally, the proposed enhanced Master–Slave control for accurate load sharing among parallel standalone AC microgrids validated using real‐time simulator and experimental results is provided to verify the effectiveness of the proposed control scheme. [ABSTRACT FROM AUTHOR]

The predictive torque control (PTC) of electric motor drive is based on the principle that the determined optimum voltage vector will be applied to the motor in the next cycle. PTC with one-step prediction cannot obtain an experimental motor speed control, because in the real-time implementation, there is a single sampling delay between input and optimal actuation due to a large number of real time calculations. The delay time problem could be solved by modifying the optimization steps by using the two-step prediction of PTC model. In this research PTC with two step prediction is applied to control two parallel induction motor fed by a single inverter using two strategies, namely master-slave and average scheme. The experimental results of the dual parallel induction motor fed by a single inverter using master-slave and average scheme are shown in this paper. From these result, the PTC with two step prediction using these schemes is applicable in controlling the two parallel connected induction motors. The experimental results show that both motors can follow and approach the reference speed given for both step response and variable speed experiments. [ABSTRACT FROM AUTHOR]

An iteration-variable-correction (IVC) based method is proposed for solving optimal power flow (OPF) of transmission-distribution-coupled (TDC) systems. First, a TDC system can be divided into a single coordinator and multiple agents. Then, the basic formulation, subproblem construction, and selection of iteration variables are given based on the conventional heterogeneous decomposition algorithm (HGD). Considering the limitations of the conventional HGD, the IVC is proposed. According to the general theory of the IVC, when it is applied to solve TDC OPF, the voltage magnitude of boundary buses and the multipliers corresponding to boundary power injections will be corrected every four iterations with first-order and second-order differential operations on historical results in the previous four iterations. The quadratic convergence of the IVC is proved under several weak assumptions. The numerical experiments demonstrate that the proposed IVC has the same accuracy as the method based on the centralized OPF model. Also, better convergence and efficiency can be achieved under the IVC compared with some conventional decomposition methods, including alternating direction method of multipliers, auxiliary problem principle method, analytical target cascading method, and the HGD. [ABSTRACT FROM AUTHOR]

Rate control is the most used operation method for master–slave hydraulic manipulators. However, the trajectory from the master controlled by the operator cannot completely meet the dynamic limitations and flow restriction of the hydraulic manipulator. Continuous large errors and oscillation will occur due to flow restrictions and high-order dynamics beyond the dynamic boundaries that significantly limits the velocity tracking performance of a hydraulic manipulator. In this article, we propose a flow-limited rate control scheme for the master–slave hydraulic manipulators. The variable velocity mapping is developed, adjusting the velocities to meet the pump and valves’ flow limits. An adaptive robust rate controller of hydraulic manipulators is designed. An adaptive boundary estimator is introduced to estimate the hydraulic manipulator acceleration boundaries, and a variable structure controller is used to plan the velocities to meet dynamic limits. The proposed control scheme is tested on a hydraulic manipulator. The results show that the control scheme reduced velocity error and avoid the manipulator vibration, so the performance is improved for the hydraulic manipulator. [ABSTRACT FROM AUTHOR]

This paper presents an implementation of the parallelization of genetic algorithms. Three models of parallelized genetic algorithms are presented, namely the Master–Slave genetic algorithm, the Coarse-Grained genetic algorithm, and the Fine-Grained genetic algorithm. Furthermore, these models are compared with the basic serial genetic algorithm model. Four modules, Multiprocessing, Celery, PyCSP, and Scalable Concurrent Operation in Python, were investigated among the many parallelization options in Python. The Scalable Concurrent Operation in Python was selected as the most favorable option, so the models were implemented using the Python programming language, RabbitMQ, and SCOOP. Based on the implementation results and testing performed, a comparison of the hardware utilization of each deployed model is provided. The results' implementation using SCOOP was investigated from three aspects. The first aspect was the parallelization and integration of the SCOOP module into the resulting Python module. The second was the communication within the genetic algorithm topology. The third aspect was the performance of the parallel genetic algorithm model depending on the hardware. [ABSTRACT FROM AUTHOR]

This brief focus on the event-triggered synchronization of networked chaotic Lur’e systems. To relieve the burden of communication network with limited bandwidth, a novel memory-based event-triggered mechanism with the past information of the system is presented. The synchronization error system under the memory-based event-triggered mechanism is modeled by a distributed delay system. Applying an integral inequality based on Legendre polynomials, a novel synchronization condition is derived via linear matrix inequalities. Finally, a Chua’s circuit is adopted to illustrate the advantage of the proposed control strategy. [ABSTRACT FROM AUTHOR]

With the advent of the Internet and Internet-connected devices, modern business applications can experience rapid increases as well as variability in transactional workloads. Database replication has been employed to scale performance and improve availability of relational databases but past approaches have suffered from various issues including limited scalability, performance versus consistency tradeoffs, and requirements for database or application modifications. This paper presents Hihooi, a replication-based middleware system that is able to achieve workload scalability, strong consistency guarantees, and elasticity for existing transactional databases at a low cost. A novel replication algorithm enables Hihooi to propagate database modifications asynchronously to all replicas at high speeds, while ensuring that all replicas are consistent. At the same time, a fine-grained routing algorithm is used to load balance incoming transactions to available replicas in a consistent way. Our thorough experimental evaluation with several well-established benchmarks shows how Hihooi is able to achieve almost linear workload scalability for transactional databases. [ABSTRACT FROM AUTHOR]

Micro incision vitrectomy system (MIVS) is considered to be one of the most difficult tasks of eye surgery, due to its requirements of high accuracy and delicate operation under blurred vision environment. Therefore, robot-assisted ophthalmic surgery is a potential and efficient solution. Based on that consideration, a novel master-slave system for vitreoretinal surgery is realized. A 4-DOF remote center of motion (RCM) mechanism with a novel linear stage and end-effector is designed and the master-slave control system is implemented. The forward and inverse kinematics are analyzed for the controller implementation. Then, algorithms with motion scaling are also integrated into the control architecture for the purpose to enhance the surgeon's operation accuracy. Finally, Experiments on an eye model are conducted. The results show that the eye robotic system can fulfill surgeon's motion following and simulate operation of vitrectomy, demonstrating the feasibility of this system. [ABSTRACT FROM AUTHOR]

In this paper, we analyze the existence and stability of equilibrium of dc micro-grids under the master-slave control (where some distributed generations (DGs) are under droop control with dual-loop (Droop-DGs) and some DGs are under MPPT control (MPPT-DGs)). Firstly, the power-flow equation of the dc micro-grids under master-slave control with CPLs is obtained. Then, we transform the solvability of the power-flow equation into the existence of a fixed point for a contraction mapping. Based on Banach's fixed point theorem, a sufficient condition to guarantee the existence of the power-flow solution in dc micro-grids is derived. The condition derived in this paper is not only useful for master-slave control but also for droop control. Besides, to calculate the power-flow solution, an iterative algorithm with exponential convergence rate is proposed. Secondly, we use a singular perturbation model to predict the qualitative behavior of the system near the equilibrium point. By analyzing eigenvalues of the boundary layer system and reduced-order system Jacobian matrix, the robust stable analytic conditions of the system are obtained. The effect of the sampling delay on the system stability is analyzed, the robust stability condition is obtained by using linear matrix inequality. The simulation results verify the correctness of the proposed conditions. The obtained conditions provide a reference for establishing a reliable dc micro-grid. [ABSTRACT FROM AUTHOR]

Featured Application: The proposed IoT-based Master-Slave regionalized intelligent LED-light-controlling system can be applied to LED lights installed in buildings, communities, factories, warehouses, and other large-scale public zones where people and vehicles will pass by for a short time, thus saving energy consumption. Reducing residential and industrial electricity consumption has been a goal of governments around the world. Lighting sources account for a large portion of the whole energy/power consumption. Unfortunately, most of the existing installed lighting systems are ancient and have poor energy efficiency. Today, many manufacturers have introduced light-controlling systems into the current market. However, existing light controlling systems may not be successfully applied to buildings, streets, and industrial buildings due to high costs and difficult installation and maintenance. To combat this issue, this article presents an easy-to-install, low-cost, Master-Slave intelligent LED light-controlling system based on Internet of Things (IoT) techniques. The benefit of using the proposed system is that the brightness of the LED lights in the same zone can be changed simultaneously to save in energy consumption. Furthermore, the parameters of the LED lights can be directly set. Moreover, the related data are collected and uploaded to a cloud platform. In this article, we use 15 W T8 LED tubes (non-induction lamps) as a case study. When the proposed system is installed in a zone with few people, the energy-saving rate is as high as 90%. Furthermore, when 12 people pass by a zone within one hour, its energy-saving rate can reach 81%. Therefore, the advantages of using the proposed system include: (1) the original lamp holder can be retained; (2) no wiring is required; and (3) no server is set up. Moreover, the goal of energy saving can also be achieved. As a result, the proposed system changes the full-dark mode of the available sensor lamp to the low power low-light mode for standby. Further, it makes the sensor lamps in the same zone brighten or low-light way simultaneously, which can quickly complete large-scale energy-saving and convenient control functions of intelligent LED lighting controlling system. [ABSTRACT FROM AUTHOR]

High-performance single-transistor current source is crucial to analog design in advanced CMOS processes. Various approaches to enhance the output resistance of single-transistor current source are studied in this brief in the view of adaptive control. Then a novel compact implementation is proposed, and used to build a fully differential OTA with improved dc gain and common-mode rejection in a 55 nm CMOS with a supply of 1.1 V. [ABSTRACT FROM AUTHOR]

The interest of using robotic surgery especially for gynecology, gastroenterology and urology is increasing everyday as this technology is expected to be the first line of surgery in many medical fields in the near future. This attentiveness is due to the unique features of this method and its advantages over the open surgery and laparoscopy technique. Knowing curiously about robotic surgery, its components, characteristics, advantages and challenges is crucial to be prepared for such huge evolution and to be engaged in advancement of this new technology.

To ensure accurate active power-sharing and an improved dynamic response to DC voltages in a medium voltage DC distribution system (MVDCDS), this paper presents an adaptive master-slave (AMS) control strategy based on a novel nonlinear droop (ND) controller. This ND controller, which is based on an improved sigmoid nonlinear function, is applied to the slave converter stations. An improved sigmoid function is designed to achieve a continuous and nonlinear droop curve. Through use of the proposed ND controller, the proposed AMS strategy can achieve seamless switching between the master-slave control and droop control modes automatically. Consequently, the AMS control strategy not only guarantees precise control of the active power in the steady state but also allows a superior dynamic performance to be achieved in the transient state, during which the system suffers from both large-scale disturbances and communication failures. The effectiveness and superiority of the proposed AMS control strategy are illustrated by theoretical analyses and validated by performing hardware-in-the-loop (HIL) tests in a ±10 kV MVDCDS. [ABSTRACT FROM AUTHOR]

In this article, a model-based sensorless control method which incorporates the orthogonal master-slave adaptive notch filter (ANF) for surface mounted permanent magnet synchronous motor is proposed. Since the rotor position estimation is seriously affected by the harmonics of estimated back-electromotive force (EMF), the orthogonal master-slave ANF is designed to deal with this problem. The orthogonal master-slave ANF is developed based on the ANF with frequency adaptation. The theoretical analysis indicates that the orthogonal master-slave ANF can accurately track the specific harmonics and the fundamental wave of back-EMF. Both the satisfactory harmonics elimination and the fast response speed of filter can also be achieved at the same time. Besides, the proposed frequency adaptation algorithm overcomes the dependence of frequency convergence on the signal amplitude and the problem of “double-frequency oscillation” in the estimated frequency. And since the use of frequency adaptation, the phase-locked loop is unnecessary, which simplifies the system and enhances the reliability. The corresponding experimental results under different conditions demonstrate the effectiveness and the superiority of the proposed method. [ABSTRACT FROM AUTHOR]

Biclustering is a data mining technique that allows us to find groups of rows and columns that are highly correlated in a 2D dataset. Although there exist several software applications to perform biclustering, most of them suffer from a high computational complexity which prevents their use in large datasets. In this work we present ScalaParBiBit, a parallel tool to find biclusters on binary data, quite common in many research fields such as text mining, marketing or bioinformatics. ScalaParBiBit takes advantage of the special characteristics of these binary datasets, as well as of an efficient parallel implementation and algorithm, to accelerate the biclustering procedure in distributed-memory systems. The experimental evaluation proves that our tool is significantly faster and more scalable that the state-of-the-art tool ParBiBit in a cluster with 32 nodes and 768 cores. Our tool together with its reference manual are freely available at https://github.com/fraguela/ScalaParBiBit. [ABSTRACT FROM AUTHOR]

Despite being in use since the 1960's, clock distribution networks continue to be important, mainly since the digitalization of numerous electronic tasks, which demands precise time measures for synchronizing internal and external processes in computational and instrumentation applications. Designing clock distribution networks requires determination/estimation of the appropriate topologies and parameters that guarantee the mutual synchronization of the coupled oscillators. This problem has been largely studied in the telecommunications context, with digital hierarchies succeeding at providing precise multiplexing and switching, integrating services, and in the process, giving rise to a new era of communication. From a mathematical viewpoint, this work considers linear coupling factors, with the study of nonlinear effects still open. As the nodes of time distribution networks are phase-locked loops, considering nonlinearities is helpful for the design and operation of such systems. Herein, an overview of possible solutions concerning topologies and parameters is presented, allowing performance hints regarding network architectures and parameters to help designers. The main contribution is to put together and compare each solution while taking nonlinearities into account and to associate the application to be supported with the best clock distribution solution, thus providing simple rules of thumb for system design. • Acceptable one-way clock distribution networks are chain or star. • Acceptable two-way clock distribution networks are chain or double-loop. • In well controlled environments, one way topologies are better solutions. • In noisy environments, two way topologies are better solutions. [ABSTRACT FROM AUTHOR]

The present study aims to evaluate the advantages of a master-slave robotic rehabilitation therapy in which the patient is assisted in real-time by a therapist. We have also explored if this type of strategy is applicable in a tele-rehabilitation environment. A pilot study has been carried out involving 10 patients who have performed a point-to-point rehabilitation exercise supported by three assistance modalities: fixed assistance (without therapist interaction), local therapist assistance, and remote therapist assistance in a simulated tele-rehabiliation scenario. The rehabilitation exercise will be performed using an upper-limb rehabilitation robotic device that assists the patients through force fields. The results suggest that the assistance provided by the therapist is better adapted to patient needs than fixed assistance mode. Therefore, it maximizes the patient's level of effort, which is an important aspect to improve the rehabilitation outcomes. We have also seen that in a tele-rehabilitation environment it is more difficult to assess when to assist the patient than locally. However, the assistance suits patients better than the fixed assistance mode. [ABSTRACT FROM AUTHOR]

Modular parallel multi-inverters (MPMIs) with master-slave phase synchronization control is proposed for high-power wireless power transfer (WPT) where the MPMI output voltage phase is synchronized to suppress current circulation by compensating for the time delay of the slave inverters caused by signal propagation delay. Different power levels can be conveniently satisfied by flexibly adjusting the number of MPMIs. A modeling method based on the energy-amplitude and phase is developed and linearized to get the slowly changing phase variable and to analyze the system dynamic characteristics at its operating point. To achieve the required dynamic performance of the proposed model, the parameters of a PI controller are obtained by calculating the required settling time and overshoot of the closed-loop dominant poles. A 20.07 kW WPT prototype supplied by three MPMIs with an efficiency of 92.17% was designed and tested. Experimental results show that the proposed modeling method and controller design achieved both good performances of circulating current suppression and MPMIs output voltage phase synchronization. [ABSTRACT FROM AUTHOR]

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In this paper, an improved variational adaptive Kalman filter for cooperative localization with inaccurate prior information is proposed, in which the prior scale matrix of the one-step prediction error covariance matrix is adaptively estimated by using the expectation-maximization algorithm. A novel alternate iteration strategy is proposed to reduce the computational complexity of the proposed method. Convergence analysis and theoretical comparisons with the existing advanced adaptive Kalman filtering methods are also provided. Based on this, a new master-slave cooperative localization method is proposed. Lake experiment results of cooperative localization for autonomous underwater vehicles demonstrate the advantages of the proposed method over existing methods. Compared with the cutting-edge adaptive master-slave cooperative localization method, the proposed method has been improved by 22.52% in average localization error but no more than twice computational time is needed. [ABSTRACT FROM AUTHOR]

The handle design of telemanipulation master devices has not been extensively studied so far. However, the master device handle is an integral part of the robotic system through which the user interacts with the system. Previous work showed that the size and shape of the functional rotational workspace of the human-robot system and its usability are influenced by the design of the master device handle. Still, in certain situations, e.g., due to user preference, a specific grasp type handle might be desired. Therefore, in this article, we provide a systematic approach on how to assess and adjust the functional rotational workspace of a human-robot system. We investigated the functional rotational workspace with two exemplary grasp type handles and two different mounting orientations for each handle. The results showed that by adapting the handle orientation in the home configuration of the telemanipulator, the functional rotational workspace of the human-robot system can be adjusted systematically to cover more of the mechanical workspace of the master device. Finally, we deduct recommendations on how to choose and adjust a telemanipulator handle. [ABSTRACT FROM AUTHOR]

This paper proposes an energy storage system (ESS) for recycling the regenerative braking energy in the high-speed railway. In this case, a supercapacitor-based storage system is integrated at the DC bus of the back to back converter that is connected to the two power phases of the traction power system (TPS). In order to ensure the suitability of the ESS in the TPS, the operation modes are classified by considering the load conditions of the TPS and the state-of-charge limit of the supercapacitor. Then, a master-slave control strategy with a central controller is proposed. In which, the central controller realizes the flexible management for all operation modes, by means of the state machine logic. Meanwhile, the master-slave control serves for coordinating the operation of the multiple converters according to the commands from the central controller. Finally, the capabilities of the proposed ESS are validated by sufficient experiments under different operation modes and the simulation based on the field data. [ABSTRACT FROM AUTHOR]

The surface-to-surface master–master contact treatment is a technique that addresses pointwise contact between bodies with no prior election of slave points, as in master–slave case. For a given configuration of contact-candidate surfaces, one needs to find the material points associated with a pointwise contact interaction. This is the local contact problem (LCP). The methodology can be applied together with numerical models such as geometrically nonlinear finite elements, discrete elements and multibody dynamics. A previous publication has addressed the possibility of degenerating the local contact problem, which yields the derivation of point-surface, curve-surface and other simplifications on the geometric treatment in the same mathematical formulation, sharing a single numerical implementation. This has useful applications for singularities or non-uniqueness scenarios on the LCP. The present work provides a framework for the degenerated master–master contact formulation including friction. An enhanced friction model is proposed, accounting for a combination of elastic and dissipative effects at the interface. Details of derivations and numerical implementation are given as well as examples related to beam-shell interaction. [ABSTRACT FROM AUTHOR]

This paper introduces a novel successive-intersection-approximation-based power flow method for integrated transmission and distribution networks (I-T&D). In this method, the entire I-T&D is split into the transmission network part, distribution network part, and boundary part. Then, alternate iterations are processed between a transmission network (TN) and several distribution networks (DNs) by exchanging the voltage and power injection of boundary buses. Particularly, the voltage magnitude of the boundary buses will be modified every two iterations by obtaining an intersection with the results in the previous two iterations. The local quadratic convergence of the method is proved strictly. The numerical experiment demonstrates that the proposed method has the same accuracy as the method based on the global model. Also, better convergence and efficiency can be achieved under the proposed method compared with the master-slave-splitting method in several different circumstances, DNs with loops, DNs with distributed generations, DNs with on-load tap changers, large-scale systems, etc. Besides, the proposed method is applied in the contingency analysis, achieving satisfying convergence and efficiency. [ABSTRACT FROM AUTHOR]

To improve power supply reliability when enabling energy exchange among multiple dc microgrids (MGs) as well as effectively avoid overload or uncertainty, this paper presents a distributed cluster cooperation strategy through establishing a master-slave control framework over two-layer switching topologies. According to the physical cluster structure of multiple dc MGs, all distributed generators (DGs) within each dc MG cluster are divided into one master-DG and multiple slave-DGs. All master-DGs, allowed to information interaction among multiple MG clusters, constitute the master control layer; whereas slave-DGs, enabled to information exchange within each MG cluster, then together form the slave control layer. Once the stable operation is realized among all master-DGs, the stability of all slave-DGs can be automatically driven by their respective master-DGs. Eventually the weighted average voltage of all DGs can be regulated to their references, meanwhile, the accurate current sharing can be simultaneously realized not only within each dc MG cluster but also among multiple dc MG clusters. All controllers are fully distributed and can be applied in all sparse two-layer switching network topologies, control time constant related sufficient conditions are also derived to ensure the whole system stability. The effectiveness of the results is verified through different cases in MATLAB/SimPowerSystems. [ABSTRACT FROM AUTHOR]

With the increasing penetration of renewable resources and the DC nature loads, voltage source converter (VSC) based DC distribution systems take an important position in the future smart grid architecture due to many distinguishing features. However, DC distribution systems face frequent power disturbances and multi-mode swithcing problem, how to achieve better DC voltage control and reasonable power sharing performance under various disturbances is still a challenge. After analyzing the control structure and master–slave (M–S) method, an equal loading rate based M–S method is proposed based on the power sharing capability of the VSC station. Moreover, error analysis of the proposed M–S method is conducted and a correction method for the proposed M–S method is developed. The proposed M–S method not only preserves the advantage of M–S method, but also changes the power instructions accordingly based on the operation state of the whole DC distribution system. Moreover, the proposed M–S method is simple and easy to implement. Lastly, simulations of a three-terminal VSC based DC distribution system are conducted in PSCAD/EMTDC to validate the effectiveness of the proposed M–S method. [ABSTRACT FROM AUTHOR]

IEEE 1588, built on the classical two-way message exchange scheme, is a popular clock synchronization protocol for packet-switched networks. Due to the presence of random queuing delays in a packet-switched network, the joint recovery of the clock skew and offset from the timestamps of the exchanged synchronization packets can be treated as a statistical estimation problem. In this paper, we address the problem of clock skew and offset estimation for IEEE 1588 in the presence of possible unknown asymmetries between the deterministic path delays of the forward master-to-slave path and reverse slave-to-master path, which can result from incorrect modeling or cyber-attacks. First, we develop lower bounds on the mean square estimation error for a clock skew and offset estimation scheme for IEEE 1588 assuming the availability of multiple master-slave communication paths and complete knowledge of the probability density functions (pdf) describing the random queuing delays. Approximating the pdf of the random queuing delays by a mixture of Gaussian random variables, we then present a robust iterative clock skew and offset estimation scheme that employs the space alternating generalized expectation-maximization (SAGE) algorithm for learning all the unknown parameters. Numerical results indicate that the developed robust scheme exhibits a mean square estimation error close to the lower bounds. [ABSTRACT FROM AUTHOR]

Absolute stability analysis of bilateral teleoperation systems are typically model-based. Under borderline conditions of absolute stability, depending on the degree of uncertainty in the dynamic model of the teleoperator and existing noise, the system may behave as potentially unstable when the model-based analysis predicts otherwise. In this article, we propose a methodology to experimentally verify the absolute stability of master-slave teleoperation systems. Since absolute stability demands bounds of all possible environments, we achieve this by conducting only three experiments that are often experienced in teleoperation: free slave, mass-carrying slave and locked slave (rigid environment). We will validate and compare our proposed method with the benchmark Llewellyns absolute stability criterion. Furthermore, we will examine the robustness of the proposed method and will provide guidelines for choosing the mass for the mass-carrying load condition. [ABSTRACT FROM AUTHOR]