Rapid-Erection Backstepping Tracking Control for Electrohydraulic Lifting Mechanisms of Launcher Systems

Uncertainties and disturbances widely exist in electrohydraulic lifting mechanisms of launcher systems, which may worsen the rapid-erection tracking accuracy and even make the system unstable. To deal with the issue, an asymptotic tracking control framework is developed for electrohydraulic lifting mechanisms of launcher systems. Firstly, the dynamic equations and state-space forms of the electrohydraulic lifting mechanism are modeled. Based on the system model, a nonlinear rapid-erection robust controller is constructed to achieve the improvement of the system control performance, in which a nonlinear feedback term is employed to remove the effects of uncertainties and disturbances on tracking performance. Compared to the existing results, the asymptotic tracking stability of the closed-loop system can be assured based on the Lyapunov theory analysis. In the end, the simulation example of an actual electrohydraulic lifting mechanism of the launcher system is done to validate the effectiveness with the proposed controller.

A Linear Regression Model for THD Sensitivity in PV Based Microgrid with Varying Insolation Levels

Solar PV systems can be used for powering small microgrids in rural area of developing countries. Generally, a solar power microgrid consists of a PV array, an MPPT, a dc-dc converter and an inverter, particularly as the general loads are A.C in nature. In a PV system, reactive current, unbalancing in currents, and harmonics are generated due to the power electronics-based converters as well as nonlinear loads (computers induction motors etc). Thus, estimation of the harmonics levels measured by the Total Harmonic Distortion (THD) is an essential aspect of performance assessment of a solar powered microgrid. A major issue that needs to be examined is the impact of PV system control parameters on the THD. In this paper, we take up this assessment for a small PV based rural microgrid with varying levels of solar irradiance. A Simulink model has been developed for the study from which the THD at equilibrium conditions is estimated. This data is in turn used to design a generalized Linear Regression Model, which can be used to observe the sensitivity of three control variables on the magnitude of the THD. These variables are: Solar Irradiance levels, Power Factor (PF) of connected load magnitude of the connected load (in kVA) The results obtained show that the greatest sensitivity is obtained for load kVA variation.

Fully Isolated Quad-Port Electric Energy Routing Converter with Medium- and High-Voltage Grid Connection Capability

Aiming at the demand for medium- and high-voltage port access capability in energy router, this study proposes a quad-port DC/DC converter topology scheme based on modular multilevel converter (QP-M2DC). Compared with the traditional multiterminal energy routing converter, it has the advantages of high modularity, strong flexibility, and high power density. In addition, for the modular structure on the medium- and high-voltage sides, this study proposes a narrow phase-shift cyclic modulation strategy, which reduces the system need for voltage balance control and simplifies the overall system control. This study comprehensively introduces and analyses the QP-M2DC topology, working principle, high-frequency link equivalent, and power characteristics, then establishes an equivalent model of system control, and proposes a control scheme for a multiterminal energy routing converter. Finally, a simulation model of the system is established through PLECS, and the simulation results show that in such a narrow phase-shift modulation strategy, the proposed topology can have stable operation in a variety of patterns, reduce the capacitance, and achieve better voltage balance at the same time. The experimental results show the converter efficiency of up to 97.8%. It further shows the superiority of the proposed topology structure and the correctness and effectiveness of the proposed control schemes.

Concurrent Control Algorithm for Large-scale Remote Multi-user Information Management System

When the current concurrency control algorithm is used to control of the multi-user information management system, the system’s channel transmission capability is low, and the time it takes is long. In this paper, a concurrency control algorithm for large-scale remote multi-user information management system is proposed. According to the average use rate of the large-scale remote multi-user information management system, the concurrency control structure and state of the system are analyzed and judged; Through the analysis of the results, the delay of data link layer in multi-user information management system is carried out modeling; Combined with the queuing delay and accessing delay, the large-scale remote multi-user information management system control can be realized. Experimental results show that the channel utilization rate of the proposed algorithm is over 98.3%, which can transmit large amounts of information in a relatively short time and concurrency control of information management system. Therefore, the proposed algorithm has high channel utilization and efficiency of information transmission

Central Nervous System Control of Glucose Homeostasis: A Therapeutic Target for Type 2 Diabetes?

Historically, pancreatic islet beta cells have been viewed as principal regulators of glycemia, with type 2 diabetes (T2D) resulting when insulin secretion fails to compensate for peripheral tissue insulin resistance. However, glycemia is also regulated by insulin-independent mechanisms that are dysregulated in T2D. Based on evidence supporting its role both in adaptive coupling of insulin secretion to changes in insulin sensitivity and in the regulation of insulin-independent glucose disposal, the central nervous system (CNS) has emerged as a fundamental player in glucose homeostasis. Here, we review and expand upon an integrative model wherein the CNS, together with the islet, establishes and maintains the defended level of glycemia. We discuss the implications of this model for understanding both normal glucose homeostasis and T2D pathogenesis and highlight centrally targeted therapeutic approaches with the potential to restore normoglycemia to patients with T2D.

Towards a Modular Elbow Exoskeleton: Concepts for Design and System Control

In industrial workplaces, strenuous, repetitive, and long-term tasks at head level or above as well as carrying heavy loads may lead to musculoskeletal disorders of different task dependent body parts. With an increasing trend towards wearable support systems, there is already a large quantity of exoskeletons that may support the user during movements, or stabilize postures, in order to reduce strain on various parts of the body. However, most commercially available exoskeletons mainly focus on the back and shoulder support. Only a few of them address the elbow joint, despite it being prone to injury. Therefore, this paper discusses different possible design and control concepts of modular elbow exoskeletons. The modular architecture potentially enables coupling to existing commercial- and research-associated systems, through appropriate interfaces. Different morphological structures and control mechanisms are assessed in respect to their ability to extend common exoskeletons for back and shoulder support. Based on these considerations, a first functional passive prototype is presented, which supports the flexion of the elbow joint and can be coupled to an existing exoskeleton. In future work, the prototype may be used for further elaboration and practical investigations in laboratory settings to evaluate its technical functionality and biomechanical effects on the user.

Operation Control and Analysis of a Hybrid AC/DC Microgrid.

Distributed renewable energy production is making smart microgrid concepts based on AC, DC, and hybrid-MG design more attractive (DRE). In light of the growing population and the pressing need to minimize the load, research into effective control techniques and architectural solutions is a hot topic right now. "However, a comprehensive and coordinated literature assessment of hierarchical control approaches based on diverse configurations of the microgrid (MG) architecture has been explored relatively little in the past.'' Primary, secondary, and tertiary methods to MG system control are outlined in this suggested method. Primary, secondary and third-tier techniques are examined for each MG structure in a short literature review. In addition, the paper offers the best and worst aspects of current control methods. In addition, a simulation research connected to the literature review's future trends in MG control is offered as a further contribution to this subject. Since renewable energy supplies are intermittent in nature, a hybrid microgrid is needed to minimize overall deficit inadequacies and increase system dependability. This is due to the depletion of natural resources and to the intermittent nature of renewable energy resources. Using a hybrid microgrid, the present distributed and concentrated load situations may be accommodated. In order to better understand how the hybrid microgrid may be integrated, optimized and controlled, there is a growing demand for research. It is necessary to do a thorough evaluation of the performance, efficiency, dependability, security, design flexibility, and cost-effectiveness of a hybrid microgrid. Issues such as AC and DC microgrids integrating into a single hybrid microgrid are discussed in this paper, as well as how to manage renewable energy resources in a cost-effective manner and how to place the optimal number of feeders in a microgrid. There is a quick overview of the primary research fields, with the goal of finding the research gap that may further enhance the grid's performance. ''New hybrid microgrid solutions are being offered in light of current study trends that have been determined to be the most effective and most-friendly." Research, comparative analysis, and further development of new methodologies related to hybrid microgrids will be aided by this study as the foundation for future work