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We consider a manufacturer that produces in response to a stochastic demand and emits pollution during the production process. Industrial pollutants released into the air are characterised by spatial variability and heterogeneity, and the precision of instruments for measuring stochastic pollution stocks varies widely across pollutants. Consequently, commitment (open-loop) strategies to control production and associated emissions are considered more practical than contingent (feedback) approaches when manufacturers are concerned about environmental consequences. In this article, we derive an optimal, open-loop control policy over an infinite time horizon and show a condition that ensures that such a policy induces asymptotic convergence of expected inventory stock and pollution stock trajectories to unique steady states. Moreover, we find that the variance in the pollution stock also converges asymptotically to a unique steady state, which is critical for prevention of irreversible environmental consequences. We show that environmental uncertainty affects inventories, leading, in the long run, to lower expected steady-state inventory stocks. We compare feedback and open-loop production policies and show that though there are losses associated with the inability to track inventory and pollution stocks accurately and thus applying the open-loop control instead of feedback, the expected long-term inventory and pollution stocks are not affected. [ABSTRACT FROM AUTHOR]

Undesired dynamics during a rocket launch can lead to failures such as the fatigue and fracture of a whole spacecraft. Moreover, low-frequency vibration in a spacecraft cannot effectively be controlled through traditional passive isolation. We thus present a novel active–passive hybrid vibration isolation technique based on a piezoelectric hybrid constrained-layer damping treatment to reduce whole-spacecraft vibration and improve the vibration isolation bandwidth. The new technique has the advantages of an active–passive hybrid piezoelectric network and passive constrained-layer damping features. The installation location and structural form of the presented treatment on the satellite–launch vehicle system are proposed by simplifying the link mode of the satellite and rocket structure. On this basis, governing equations of the simplified whole-spacecraft vibration isolation system with the presented treatment are derived by virtue of Hamilton's principle combined with the Rayleigh–Ritz method. The active controller is designed by adopting a velocity feedback control strategy. The vibration suppression effect is illustrated in numerical simulations of the open-loop and closed-loop characteristics. It is notable that good vibration attenuation behaviors are realized in the whole-spacecraft hybrid isolation system. Furthermore, a prototype of the system with the presented treatment is designed and experimental investigations are carried out to verify the accuracy of the theoretical investigation, further illustrating the feasibility and effectiveness of the presented control scheme. [ABSTRACT FROM AUTHOR]

In the active vibration reduction of two-dimensional structures, piezoelectric actuators of regular shapes, e.g. rectangular, circular, are commonly used. However, the shape of the transducers can be irregular, asymmetric (a-PZT), and its geometry can be an object for optimization. The paper presents an experimental validation of the application of optimal shaped a- PZT in the active reduction of triangular plate vibrations. Optimization was based on the criterion of the maximum bending moment. This means that the center of a-PZT is located at the point where the bending moment of the plate has reached its absolute maximum. The isosceles right triangular plate with simply supported edges was chosen as the research object. The research confirms the validity of the criterion used for optimization and may be an introduction to considering the use of optimal a-PZT in the active reduction of vibrations for more complex structures.

For the VSC-HVDC system transmitting new energy， poor parameter matching between the new energy controller and the VSC-HVDC controller can lead to sub-synchronous and super-synchronous oscillation. To address this， an open-loop strategy based on virtual synchronous generator （VSG） control has been adopted. This strategy eliminates the inner and outer loops and the phase lock of traditional closed-loop control methods， optimizing the impedance characteristics of the VSC-HVDC system and reducing the risk of sub-synchronous and super-synchronous oscillations of new energy. It is also compatible with both islanded and grid-connected operating modes. To address bipolar power imbalance and excessive short-circuit current after faults in open-loop control， bipolar power balancing and fault ride-through （FRT） strategies have been proposed. The effectiveness of the proposed VSG control and FRT strategies has been validated through RTDS simulations.

In this work, we focus on an infinite horizon mean-field linear-quadratic stochastic control problem with jumps. Firstly, the infinite horizon linear mean-field stochastic differential equations and backward stochastic differential equations with jumps are studied to support the research of the control problem. The global integrability properties of their solution processes are studied by introducing a kind of so-called dissipation conditions suitable for the systems involving the mean-field terms and jumps. For the control problem, we conclude a sufficient and necessary condition of open-loop optimal control by the variational approach. Besides, a kind of infinite horizon fully coupled linear mean-field forward-backward stochastic differential equations with jumps is studied by using the method of continuation. Such a research makes the characterization of the open-loop optimal controls more straightforward and complete. [ABSTRACT FROM AUTHOR]

Copyright of Zhejiang Electric Power is the property of Zhejiang Electric Power Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In the active vibration reduction of two-dimensional structures, piezoelectric actuators of regular shapes, e.g. rectangular, circular, are commonly used. However, the shape of the transducers can be irregular, asymmetric (a-PZT), and its geometry can be an object for optimization. The paper presents an experimental validation of the application of optimal shaped a-PZT in the active reduction of triangular plate vibrations. Optimization was based on the criterion of the maximum bending moment. This means that the center of a-PZT is located at the point where the bending moment of the plate has reached its absolute maximum. The isosceles right triangular plate with simply supported edges was chosen as the research object. The research confirms the validity of the criterion used for optimization and may be an introduction to considering the use of optimal a-PZT in the active reduction of vibrations for more complex structures. [ABSTRACT FROM AUTHOR]

Copyright of Electronic Components & Materials is the property of Electronic Components & Materials and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The vector or pest control is essential to reduce the risk of vector-borne diseases or crop losses. Among the available biological control tools, the sterile insect technique (SIT) is one of the most promising. However, SIT-control campaigns must be carefully planned in advance in order to render desirable outcomes. In this paper, we propose SIT-control intervention programs that can avoid the real-time monitoring of the wild population and require to mass-rear a minimal overall number of sterile insects, in order to induce a local elimination of the wild population in the shortest time. Continuous-time release programs are obtained by applying an optimal control approach, and then laying the groundwork of more practical SIT-control programs consisting of periodic impulsive releases. [ABSTRACT FROM AUTHOR]

Soft robots distinguish themselves from traditional robots by embracing flexible kinematics. Because of their recent emergence, there exist numerous uncharted territories, including novel actuators, manufacturing processes, and advanced control methods. This research is centred on the design, fabrication, and control of a pneumatic soft robot. The principal objective is to develop a modular soft robot featuring multiple segments, each one with three degrees of freedom. This yields a tubular structure with five independent degrees of freedom, enabling motion across three spatial dimensions. Physical construction leverages tin-cured silicone and a wax-casting method, refined through an iterative processes. PLA moulds that are 3D-printed and filled with silicone yield the desired model, while bladder-like structures are formed within using solidified paraffin wax-positive moulds. For control, an empirically fine-tuned open-loop system is adopted. This paper culminates in rigorous testing. Finally, the bending ability, weight-carrying capacity, and possible applications are discussed. [ABSTRACT FROM AUTHOR]

Nowadays saving the planet's resources plays a very important role in improving our life conditions. The purpose of the paper is to supply the separately excited dc motor by using different chopper circuits. A very sustainable solution is to replace the resistors from classic theory with dc choppers for better efficiency. The armature voltage can be controlled by using IGBT chopper and the PWM signal received from controller is done with a dedicated block created by MATLAB environment. The advantages of developing this technique are that the speed changes proportionally with armature voltage and inversely with field voltage by keeping field and armature voltage constant respectively. The chopper designed with IGBT and Diode modules offers good control at any frequency value and the speed, the armature current and electromagnetic torque of DC motor can be control. In this paper, different choppers had been simulating were working in four quadrants for supply an excited dc motor by using Matlab program. [ABSTRACT FROM AUTHOR]

Piezoelectric actuators have been widely applied to precision positioning platforms. However, the positioning accuracy of piezoelectric ceramic has been significantly affected by its characteristics of hysteresis. Owing to the voltage-keeping feature of capacitive load for piezoelectric ceramic, this paper has proposed a switch-based driving in sequence method, which alternately drives each layer of PZT by using switches. Based on the driving in sequence method, the proposed method is capable of reducing the hysteresis to 1/N of the hysteresis under traditional voltage driving method, while significantly lowering the scale and cost of hardware, compared with the previous driving in sequence method. Thus, it allows for application to hundreds of layers of piezoelectric ceramic. According to experiment results, the hysteresis under different frequencies from 0.1 to 500 Hz for homemade seven-layer piezoelectric ceramic can be reduced from 12.5 to 2.1%. Furtherly, the residual hysteresis can be corrected by applying a simple quadratic-polynomial feedforward control, and the hysteresis is constrained within 0.8%, even with feedforward parameters that are not strictly calibrated. The dual-amplifier driving in sequence method proposed in this paper can significantly reduce the hysteresis in open-loop control of piezoelectric stack actuators, effectively improving the positioning and driving performance and saving cost. [ABSTRACT FROM AUTHOR]

The purpose of the present research endeavor is to propose a novel control strategy for a DC-DC electrical converter realized as a switched circuit. The present endeavor is based on an early work by Leonard and Krishnaprasad where a prototypical DC-DC converter was modeled as a state space dynamical system and controlled by an open-loop strategy based on Lie group theory. In this work, we shall rather introduce a closed-loop control strategy based on maximum convergence rate, study some features of the novel method, and illustrate its behavior by numerical simulations. A numerical comparison of the two methods complements the paper. The numerical comparison shows how the proposed feedback control method outperforms the static one in terms of convergence rate and resiliency against parameters mismatch. [ABSTRACT FROM AUTHOR]

Abstract The architecture and a flight test campaign of a small‐scale testbed aimed at aerodynamic and dynamic characterization of airborne wind energy systems are presented. The testbed involves a two‐line rigid‐framed delta kite and an automatic ground station for the lateral control of the kite and reel‐in/reel‐out of the two tethers. The environment, and the states of the kite, the tethers and the actuators are measured by a set of on‐ground and onboard sensors that include, among others, an inertial measurement unit, GNSS receivers, load cells, actuator encoders, a wind station, and a visual motion tracking (VMT) system based on three cameras and an artificial neural network (YOLOv2). The results of a 5‐min flight, including the take‐off, cross‐wind flight, and landing, were used to analyze the capabilities of the testbed. It was shown that the time derivative of the kite course angle exhibits a linear correlation with both the delayed steering input and the delayed differential tether tension, being the dispersion lower for the latter. The intrinsic and extrinsic calibrations proposed for the VMT system led to a good agreement between the estimation of the kite position and course angle provided by the VMT system and the onboard computer. Moreover, although the YOLOv2 algorithm failed in the detection of the kite within around 5% of the images, the simultaneous non‐detection from the three cameras was below 0.1% during the full flight. Such a reliability suggests that a VMT system can be used as a redundant or backup sensor for the GNSS.

This paper introduces a new gripper mechanism that is capable of grasping objects of various sizes and shapes without the need for a closed-loop control system. Industries such as the food and beverage industry are seeking innovative soft grippers with a simplified control system. The proposed design utilizes a rotary mechanism with springs to achieve both force-closure and form-closure grasping. The design sets itself apart from most soft grippers with its ability to offer grasping forces in all lateral directions. The gripper is designed in a cylindrical shape and is actuated by a stepper motor with a gearbox to enhance the torque. Three stacked curvilinear and linear rails convert the motor's rotational motion into linear motion. The grasping component consists of three curved parts, each incorporating numerous compression springs. Currently, the gripper can effectively grasp objects ranging from five to nine centimeters in diameter, with a maximum height of ten centimeters. However, the design is scalable based on specific application requirements. A comprehensive CAD model of the mechanism was developed, and multiple analyses were conducted, including motion, topology, and stress analyses. Finally, a functional prototype of the gripper was constructed and successfully tested for grasping fruits and vegetables of different sizes and shapes. This research can be further expanded to explore the application of the gripper in space exploration with its novel and completely electro-mechanical foundation. [ABSTRACT FROM AUTHOR]

The architecture and a flight test campaign of a small-scale testbed aimed at aerodynamic and dynamic characterization of airborne wind energy systems are presented. The testbed involves a two-line rigid-framed delta kite and an automatic ground station for the lateral control of the kite and reel-in/reel-out of the two tethers. The environment, and the states of the kite, the tethers and the actuators are measured by a set of on-ground and onboard sensors that include, among others, an inertial measurement unit, GNSS receivers, load cells, actuator encoders, a wind station, and a visual motion tracking (VMT) system based on three cameras and an artificial neural network (YOLOv2). The results of a 5-min flight, including the take-off, cross-wind flight, and landing, were used to analyze the capabilities of the testbed. It was shown that the time derivative of the kite course angle exhibits a linear correlation with both the delayed steering input and the delayed differential tether tension, being the dispersion lower for the latter. The intrinsic and extrinsic calibrations proposed for the VMT system led to a good agreement between the estimation of the kite position and course angle provided by the VMT system and the onboard computer. Moreover, although the YOLOv2 algorithm failed in the detection of the kite within around 5% of the images, the simultaneous non-detection from the three cameras was below 0.1% during the full flight. Such a reliability suggests that a VMT system can be used as a redundant or backup sensor for the GNSS. [ABSTRACT FROM AUTHOR]

We show that for stabilization of Boolean control networks (BCNs) with unobservable initial states, open-loop control and close-loop control are not equivalent. An example is given to illustrate the nonequivalence. Enlightened by the nonequivalence, we explore open-loop set stabilization of BCNs with unobservable initial states. More specifically, this issue is to investigate that for a given BCN, whether there exists a unified free control sequence that is effective for all initial states of the system to stabilize the system states to a given set. The criteria for open-loop set stabilization is derived and for any open-loop set stabilizable BCN, every time-optimal open-loop set stabilizer is proposed. Besides, we obtain the least upper bounds of two integers, which are respectively related to the global stabilization and partial stabilization of BCNs in the results of two literature articles. Using the methods in the two literature articles, the least upper bounds of the two integers cannot be obtained. [ABSTRACT FROM AUTHOR]

Soft robots distinguish themselves from traditional robots by embracing flexible kinematics. Because of their recent emergence, there exist numerous uncharted territories, including novel actuators, manufacturing processes, and advanced control methods. This research is centred on the design, fabrication, and control of a pneumatic soft robot. The principal objective is to develop a modular soft robot featuring multiple segments, each one with three degrees of freedom. This yields a tubular structure with five independent degrees of freedom, enabling motion across three spatial dimensions. Physical construction leverages tin-cured silicone and a wax-casting method, refined through an iterative processes. PLA moulds that are 3D-printed and filled with silicone yield the desired model, while bladder-like structures are formed within using solidified paraffin wax-positive moulds. For control, an empirically fine-tuned open-loop system is adopted. This paper culminates in rigorous testing. Finally, the bending ability, weight-carrying capacity, and possible applications are discussed.

These days, societies need for energy increased due to the expansion of societies, industries, and technology. The production of electricity from renewable energy sources such as solar energy, which does not harm the environment and has little pollution, has attracted the attention of many researchers and engineers. This article will present a new plan for the dual polar axis solar tracker, its design and construction in laboratory dimensions, and the experimental evaluation of its performance using the open-loop control method. For this purpose, after examining the advantages and disadvantages of the previous designs, a new and different conceptual design for the tracker is proposed. Among the features of the proposed tracker, we can point out the ability to combine, install and operate quickly and easily, the self-locking feature, and the ability to rotate 360 degrees around both axes. This tracker has no restrictions for use in different geographical areas, including areas near the North or South Pole and in the early and late hours of the day when the direction of the sun's radiation is strongly inclined. In the following, the detailed design of the proposed detector and the presentation of the open-loop control method will be discussed. Finally, by conducting experimental tests, the production power of the proposed detector is evaluated in comparison with a fixed solar panel. Based on the results, the electricity energy produced from the proposed solar tracker is 49% more than the fixed solar panel. [ABSTRACT FROM AUTHOR]

Summary: This article investigates a modelization of the energy management strategy of a grid‐tied photovoltaic (PV), wind generator, and battery system. The model uses a smart metering system to collect data from various electrical components of a microgrid. The power optimization strategy is modeled under demand response, including time‐of‐use pricing to create a home's energy flow more efficiently. Two optimal control strategies are developed to coordinate energy expenses, expressed as the cost of minimizing electricity supplied by the utility grid and maximizing the opportunity for energy to sell to the grid. A nonlinear open‐loop control and quadratic programming using model predictive control (MPC) are compared to assess the performance of the developed model. The design model takes into consideration the operational cost of batteries and degradation. The importance of the energy storage system is demonstrated in the context of energy conservation and gain on the demand side. MPC's capacity to specify the proper control and forecast future system reaction enables the proposed method to ensure significant daily energy and cost savings from 70.44 to 24.74 $ day−1 in the first scenario (without disturbances) and from 70.44 to 18.24 $ day−1 in the second case (with disturbances). In both methods, the net savings of greenhouse gas are approximately 288.10 (kgCO2‐eq) and 338.87 (kgCO2‐eq). These show better performance of the MPC compared to the linear model. Highlights: Investigate the dynamic performance of an intelligent home energy management scheme.Implement a grid‐tied photovoltaic, wind turbine, and energy storage system.Use intelligent metering to collect data from various electrical components of a smart home.Compare the energy saving from an open‐loop algorithm and a model predictive control.Assess the topmost benefits of the optimal control method of grid‐tied distributed energy resources. [ABSTRACT FROM AUTHOR]

The realization of the desired damping characteristics based on magnetorheological (MR) dampers is important for semi-active control and useful for the matching process of suspension damper. To reduce the cost of the control system and improve the output accuracy of the desired damping force, this study proposes an open-loop control method featuring an accurate inverse model of the MR damper and a tripolar current driver. The reversible sigmoid model is used to accurately and quickly calculate the desired current. Furthermore, the change characteristic of the desired current is analyzed qualitatively and quantitatively, which shows that the desired current needs to change suddenly to make the actual damping force velocity curve quickly approach the desired one. To meet the demand of the desired current, a tripolar current driver controlled by an improved PI control algorithm is proposed, which is with fast response and low noise. Finally, the bench test verifies that the control system can achieve different desired damping characteristics well, and the inherent error in this process is explained through the gap between the available damping force area and the desired damping characteristic curve and the crossover phenomenon of the dynamic characteristic curves of the MR damper. [ABSTRACT FROM AUTHOR]

This paper designs an optimal open-loop leader-follower control strategy of input-delay stochastic systems. The leader-follower control problem is described as an optimal problem based on Stackelberg strategies. A control strategy of the leader is given to minimize the function of $H_{2}$ norm, while a control strategy of the follower in worst case maximizing the function of $H_\infty $ norm is applied to the systems. Then the optimal leader-follower control strategy is obtained by establishing the information relationship of the forward and the backward variables with augmentation of the variables and solving several Riccati equations. At last, an example illustrates the effectiveness of the proposed strategy.

A robust input command based on multiple steps for eliminating the residual vibrations of a multimode linear system is proposed. Only the system resonant frequencies are needed to determine the step magnitudes in the shaped command. The command duration is selectable to help in designing an optimum command that compensates between the reduction in the transient vibration, the enhancement in the command robustness, and the increase in the total maneuver time. The induced transient and residual sloshing oscillations of a suspended water-filled container are suppressed using the proposed command. The dynamics of the sloshing is numerically simulated using finite element method that accommodates the interactions between the fluid, structural, and multi-body dynamics. A short move time penalty is incurred with the price of significant reduction in the liquid sloshing. The performance of the shaped command to the system parameters and the robustness to their uncertainty are investigated. An improved robust input command in the presence of uncertainties in the cable length and water depth is also introduced. The effectiveness and excellence of the proposed command is demonstrated through a comparison with multimode zero-vibration input shaper and time-optimal flexible-body control. [ABSTRACT FROM AUTHOR]

This paper introduces a new gripper mechanism that is capable of grasping objects of various sizes and shapes without the need for a closed-loop control system. Industries such as the food and beverage industry are seeking innovative soft grippers with a simplified control system. The proposed design utilizes a rotary mechanism with springs to achieve both force-closure and form-closure grasping. The design sets itself apart from most soft grippers with its ability to offer grasping forces in all lateral directions. The gripper is designed in a cylindrical shape and is actuated by a stepper motor with a gearbox to enhance the torque. Three stacked curvilinear and linear rails convert the motor’s rotational motion into linear motion. The grasping component consists of three curved parts, each incorporating numerous compression springs. Currently, the gripper can effectively grasp objects ranging from five to nine centimeters in diameter, with a maximum height of ten centimeters. However, the design is scalable based on specific application requirements. A comprehensive CAD model of the mechanism was developed, and multiple analyses were conducted, including motion, topology, and stress analyses. Finally, a functional prototype of the gripper was constructed and successfully tested for grasping fruits and vegetables of different sizes and shapes. This research can be further expanded to explore the application of the gripper in space exploration with its novel and completely electro-mechanical foundation.

• Paper title: hybrid rocket engine optimization by controlled oxidizer flow dynamics. • Mass flowrate equation was significantly simplified. • It is possible to improve the oxidizer-to-fuel ratio by varying the mass flowrate. • The thrust output of the hybrid rocket engine is stabilized. • Improvement in combustion efficiency is achieved. Rocket engines are an essential component in delivering any payload such as satellites, rovers, and probes into space. One such kind of engine is the hybrid rocket engine. Classical hybrid rocket engines have first become popular in the early 1970s. These engines, while providing combined advantages of both solid rocket motors and liquid rocket engines, as well as being relatively cheap to manufacture when compared to liquid rocket engines, exhibit drawbacks in thrust throughout the burn of the engine caused by the oxidizer to fuel ratio shifts induced by fuel regression. Their loss in efficiency is what makes them undesirable in the construction of rockets and causes companies to use the more expensive liquid rocket engines which are higher in efficiency and overall thrust output. The negative side effects of the fuel regression can be reduced by eliminating the oxidizer to fuel ratio shifts during the operation of a hybrid rocket engine. In this paper, a new approach of controlled oxidizer flow is proposed to achieve a more favourable combustion. The differential equations of the fuel mass flow rate function are numerically solved in terms of oxidizer mass flow rate, the results of which are taken as a basis to define a control function. It was demonstrated that it is possible to eliminate the oxidizer-fuel ratio shifts for all fuel types. [ABSTRACT FROM AUTHOR]

Hard-magnetic soft materials belong to a class of the highly deformable magneto-active elastomer family of smart materials and provide a promising technology for flexible electronics, soft robots, and functional metamaterials. When hard-magnetic soft actuators are driven by a multiple-step input signal (Heaviside magnetic field signal), the residual oscillations exhibited by the actuator about equilibrium positions may limit their performance and accuracy in practical applications. This work aims at developing a command-shaping scheme for alleviating residual vibrations in a magnetically driven planar hard-magnetic soft actuator. The control scheme is based on the balance of magnetic and elastic forces at a critical point in an oscillation cycle. The equation governing the dynamics of the actuator is devised using the Euler–Lagrange equation. The constitutive behaviour of the hard-magnetic soft material is modeled using the Gent model of hyperelasticity, which accounts for the strain-stiffening effects. The dynamic response of the actuator under a step input signal is obtained by numerically solving the devised dynamic governing equation using MATLAB ODE solver. To demonstrate the applicability of the developed command-shaping scheme, a thorough investigation showing the effect of various parameters such as material damping, the sequence of desired equilibrium positions, and polymer chain extensibility on the performance of the proposed scheme is performed. The designed control scheme is found to be effective in controlling the motion of the hard-magnetic soft actuator at any desired equilibrium position. The present study can find its potential application in the design and development of an open-loop controller for hard-magnetic soft actuators. [ABSTRACT FROM AUTHOR]

PINK1 and parkin constitute a mitochondrial quality control system mutated in Parkinson's disease. PINK1, a kinase, phosphorylates ubiquitin to recruit parkin, an E3 ubiquitin ligase, to mitochondria. PINK1 controls both parkin localization and activity through phosphorylation of both ubiquitin and the ubiquitin‐like (Ubl) domain of parkin. Here, we observed that phospho‐ubiquitin can bind to two distinct sites on parkin, a high‐affinity site on RING1 that controls parkin localization and a low‐affinity site on RING0 that releases parkin autoinhibition. Surprisingly, ubiquitin vinyl sulfone assays, ITC, and NMR titrations showed that the RING0 site has higher affinity for phospho‐ubiquitin than phosphorylated Ubl in trans. We observed parkin activation by micromolar concentrations of tetra‐phospho‐ubiquitin chains that mimic mitochondria bearing multiple phosphorylated ubiquitins. A chimeric form of parkin with the Ubl domain replaced by ubiquitin was readily activated by PINK1 phosphorylation. In all cases, mutation of the binding site on RING0 abolished parkin activation. The feedforward mechanism of parkin activation confers robustness and rapidity to the PINK1‐parkin pathway and likely represents an intermediate step in its evolutionary development. Synopsis: The ubiquitin ligase parkin protects against Parkinson's disease by binding and ubiquitinating damaged mitochondria. Here, cellular, biochemical and biophysical results identify a novel feedforward mechanism involving direct parkin activation without phosphorylation by the protein kinase PINK1. Parkin has two binding sites for phosphorylated ubiquitin (pUb)The first binding site recruits parkin to damaged mitochondriaThe second site binds either pUb or the phosphorylated parkin Ubl domain, to switch on ubiquitin ligase activity [ABSTRACT FROM AUTHOR]

The paper proposes an algorithm for solving the optimal open-loop terminal control problem of two spacecraft rendezvous with constraints on their states. A system of nonlinear differential equations that describes the dynamics of the active (maneuvering) spacecraft relative to the passive spacecraft (station) in the central gravitational field of the Earth in the orbital coordinate system of coordinates related to the passive spacecraft center-of-mass is considered as an initial model. The obtained nonlinear model of the active spacecraft dynamics is linearized relative to the specified reference state trajectory of the passive spacecraft, and then it is discretized and reduced to linear recurrence relations. Mathematical formalization of the spacecraft rendezvous problem under consideration is carried out at a specified final moment of time for the obtained discrete-time controlled dynamical system. The quality of solving the problem is estimated by a convex functional taking into account the geometric constraints on the active spacecraft states and the associated control actions in the form of convex polyhedral-compacts in the appropriate finite dimensional vector space. We propose a solution of the problem of optimal terminal control over the approach of the active spacecraft relative to the passive spacecraft in the form of a constructive algorithm on the basis of the general recursive algebraic method for constructing the availability domains of linear discrete controlled dynamic systems, taking into account specified conditions and constraints, as well as using the methods of direct and inverse constructions. In the final part of the paper, the computer modeling results are presented and conclusions about the effectiveness of the proposed algorithm are made.

The paper deals with an optimal control problem in a dynamical system described by a linear differential equation with the Caputo fractional derivative. The goal of control is to minimize a Bolza-type cost functional, which consists of two terms: the first one evaluates the state of the system at a fixed terminal time, and the second one is an integral evaluation of the control on the whole time interval. In order to solve this problem, we propose to reduce it to some auxiliary optimal control problem in a dynamical system described by a first-order ordinary differential equation. The reduction is based on the representation formula for solutions to linear fractional differential equations and is performed by some linear transformation, which is called the informational image of a position of the original system and can be treated as a special prediction of a motion of this system at the terminal time. A connection between the original and auxiliary problems is established for both open-loop and feedback (closed-loop) controls. The results obtained in the paper are illustrated by examples.

This work is concerned with solving neural network-based feedback controllers efficiently for optimal control problems. We first conduct a comparative study of two prevalent approaches: offline supervised learning and online direct policy optimization. Albeit the training part of the supervised learning approach is relatively easy, the success of the method heavily depends on the optimal control dataset generated by open-loop optimal control solvers. In contrast, direct policy optimization turns the optimal control problem into an optimization problem directly without any requirement of pre-computing, but the dynamics-related objective can be hard to optimize when the problem is complicated. Our results underscore the superiority of offline supervised learning in terms of both optimality and training time. To overcome the main challenges, dataset and optimization , in the two approaches respectively, we complement them and propose the Pre-train and Fine-tune strategy as a unified training paradigm for optimal feedback control, which further improves the performance and robustness significantly. Our code is accessible at https://github.com/yzhao98/DeepOptimalControl. • Benchmarking offline vs. online learning in neural network control. • Main challenges: dataset for offline, optimization for online. • Offline learning outperforms online in optimality and speed. • Proposing "Pre-Train and Fine-Tune" paradigm for better, robust control. [ABSTRACT FROM AUTHOR]

This paper presents an experimental approach for the design of a brushless DC (BLDC) motor-driven pump that is intended to pump fluids with unknown specific gravity. We propose a control mechanism that will enable the pump to operate at a higher efficiency irrespective of fluid types. Experimental results from a prototype pump system controlled by two different open-loop controllers are used for determining the optimized closed-loop control algorithm to run the pump while tracking its higher efficiency point. A set of computer simulations is conducted based on a conventional finite-element method to design the best possible BLDC motor, which is employed in the proposed fault-tolerant and efficient pump. Experimental results are presented to validate the efficiency of the proposed pump and also compared with that of a commercial motor design simulator.

Automated insulin delivery (AID) systems enhance glucose management by lowering mean glucose level, reducing hyperglycemia, and minimizing hypoglycemia. One feature of most AID systems is that they allow the user to view "insulin on board" (IOB) to help confirm a recent bolus and limit insulin stacking. This metric, along with viewing glucose concentrations from a continuous glucose monitoring system, helps the user understand bolus insulin action and the future "threat" of hypoglycemia. However, the current presentation of IOB in AID systems can be misleading, as it does not reflect true insulin action or automatic, dynamic insulin adjustments. This commentary examines the evolution of IOB from a bolus-specific metric to its contemporary use in AID systems, highlighting its limitations in capturing real-time insulin modulation during varying physiological states., Competing Interests: Declaration of Conflicting InterestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

To improve the linearisation of the variable flow-regulate system under the open-loop control, a proportional solenoid valve with high-linearity performance was developed to meet that requirement of the high-precision and open-loop control. The design of the proportional solenoid valve evolves the optimisation of a magnetic circuit structure, the construction of a balanced pressure structure and the compensation of a feedforward control device. As for the solenoid, it is very challenging to meet the requirement of 95% linearity. A feedforward control device with the Bouc–Wen model and a quadratic inverse function model is a good solution to address the hysteresis problem and achieve better performance. The optimisation of a simple magnetic circuit with low sensitivity to the moving armature and a balance chamber for removing the pressure difference are both preconditions to make the compensation. The feedforward control device is the next step to eliminate the hysteresis problem and non-linear characteristics of the solenoid by solving model coefficients measured in the test. After the improvement in these aspects, the proportional solenoid valve can meet the demand of digital proportional flow control with >98% linearity and excellent repeatability, through the validation of both no-load and high-load performance tests.

This study proposed an approach to control voice coil motors (VCMs) installed in smartphone modules as autofocus actuators. The VCM developed in this study comprises guide rods. The magnetic field attraction force between guide rods and movable parts serves as lens restoring force. This study did not use feedback elements to avoid the stick-slip phenomenon between VCM guide rods and movable parts. Instead, this study used a high-low frequency composite signal based on the findings from a mathematical model analysis and VCM dynamic attribute analysis, preventing stick-slip and offering the VCM a more favorable positioning precision.

A smooth polynomial shaped command with an adjustable command time length is proposed for eliminating the residual vibrations of a multi-mode system. The ability of eliminating jerks and vibrational modes, regardless of their number, offers the most advantage of the proposed command. A numerical simulation is conducted to test the command's effectiveness by eliminating the residual sloshing oscillations of a liquid-filled container conveyed by an overhead crane in a rest-to-rest manoeuvre. The governing equations of the liquid free-surface level are derived by modelling the sloshing dynamics by a series of mass–spring–damper harmonics. The proposed model accounts for the coupling between the pendulum dynamics and the sloshing equivalent mechanical model. The command's robustness to the system parameters' uncertainties, liquid depth and cable length, are investigated as well. The ability of adjusting the command length and retaining higher sloshing modes in command-designing are also outlined. [ABSTRACT FROM AUTHOR]

The residuals of liquid free-surface wave oscillations induced by a rest-to-rest crane maneuver of a suspended liquid container are eliminated using a command-shaped profile. The dynamics of liquid sloshing are modeled using an equivalent mechanical model based on a series of mass-spring-damper systems. The proposed model considers the excited frequencies of the container swing motion and liquid sloshing modes. The objective is to design a discrete-time shaped acceleration profile with a variable command length that controls the moving crane-jib, while suppressing the sloshing modes. Simulations are conducted to illustrate the command effectiveness in eliminating liquid sloshing with a wide variation range of system and command-designing parameters; liquid depth, cable length, command duration, and the employing of higher sloshing modes in representing the sloshing dynamics. The command sensitivity of the input command to changes of the system parameters are treated as well. A refined and smooth input command based on suppressing the residuals of multimodes is also introduced. Furthermore, the command effectiveness was supported by a comparison with the time-optimal flexible-body control and multimode zero vibration input shaper. [ABSTRACT FROM AUTHOR]