Controllability and observability of glucose insulin glucagon system in humans

Artificial pancreas is one of the solutions to control the type1 diabetes mellitus now days. Efforts are being made to develop the artificial pancreas. The controllability and observability of the glucose insulin glucagon dynamical model is calculated which is the modified form of composite model of glucose insulin glucagon dynamics for type 1 diabetes mellitus is considered. The concept of controllability and observability for the linearized control system is used to design a feedback control. This model completely describes the glucagon affects the safety of artificial pancreas to overcome the risk of hyperglycemia. Composite model of glucagon-glucose dynamics and its extension is treated for type 1 diabetes mellitus to check the linear controllability and observability. Two cases are discussed on the basis of input of the system. For case I, insulin as the only input and glucose as an output and in case II insulin and glucagon as inputs and glucose as only output. The model is observable but not controllable in each case. This may show vital part in the progress of fully automatic artificial pancreas and stabilize the control loop system for the glucose insulin glucagon (GIG) pump to control the type 1 diabetes mellitus.     

Pancreatic β-cell signaling: toward better understanding of diabetes and its treatment

Pancreatic β-cells play a central role in the maintenance glucose homeostasis by secreting insulin, a key hormone that regulates blood glucose levels. Dysfunction of the β-cells and/or a decrease in the β-cell mass are associated closely with the pathogenesis and pathophysiology of diabetes mellitus, a major metabolic disease that is rapidly increasing worldwide. Clarification of the mechanisms of insulin secretion and β-cell fate provides a basis for the understanding of diabetes and its better treatment. In this review, we discuss cell signaling critical for the insulin secretory function based on our recent studies.     

Empirical mathematical model for dynamic manganese-enhanced MRI of the murine pancreas for assessment of β-cell function

Autoimmune ablation of pancreatic β-cells and alteration of its microvasculature may be a predictor of Type I diabetes development. A dynamic manganese-enhanced MRI (MEMRI) approach and an empirical mathematical model were developed to monitor whole pancreatic β-cell function and vasculature modifications in mice. Normal and streptozotocin-induced diabetic FVB/N mice were imaged on a 9.4 T MRI system using a 3D magnetization prepared rapid acquisition gradient echo pulse sequence to characterize low dose manganese kinetics in the pancreas head, body and tail. Average signal enhancement in the pancreas (head, body, and tail) as a function of time was fit by a novel empirical mathematical model characterizing contrast uptake/washout rates and yielding parameters describing peak signal, initial slope, and initial area under the curve. Signal enhancement from glucose-induced manganese uptake was fit by a linear function. The results demonstrated that the diabetic pancreatic tail had a significantly lower contrast uptake rate, smaller initial slope/initial area under the curve, and a smaller rate of Mn uptake following glucose activation (p < 0.05) compared to the normal pancreatic tail. These observations parallel known patterns of β-cell loss and alteration in supportive vasculature associated with diabetes. Dynamic MEMRI is a promising technique for assessing β-cell functionality and vascular perfusion with potential applications for monitoring diabetes progression and/or therapy.     

单模激光Lorenz系统与3D混沌系统之间的混沌同步

研究了异结构混沌系统之间的同步控制问题.采用非线性反馈控制方法实现了3D混沌系统和单模激光Lorenz混沌系统之间的混沌同步.根据系统的稳定性理论,得到了非线性反馈控制器的结构和反馈控制增益的取值范围.仿真模拟的结果表明:目标系统和响应系统达到完全同步,两系统状态变量随时间的演化轨迹完全一致,并且误差变量经过短暂的时间序列以后始终平稳地趋于零.仿真模拟的结果证明了这种方法的有效性.     

Multifunctional design of inertially-actuated velocity feedback controllers

The vibration of a structure can be controlled using either a passive tuned mass damper or using an active vibration control system. In this paper, the design of a multifunctional system is discussed, which uses an inertial actuator as both a tuned mass damper and as an element in a velocity feedback control loop. The natural frequency of the actuator would normally need to be well below that of the structure under control to give a stable velocity feedback controller, whereas it needs to be close to the natural frequency of a dominant structural resonance to act as an effective tuned mass damper. A compensator is used in the feedback controller here to allow stable feedback operation even when the actuator natural frequency is close to that of a structural mode. A practical example of such a compensator is described for a small inertial actuator, which is then used to actively control the vibrations both on a panel and on a beam. The influence of the actuator as a passive tuned mass damper can be clearly seen before the feedback loop is closed, and broadband damping is then additionally achieved by closing the velocity feedback loop.     

Backstepping synchronization of uncertain chaotic systems by a single driving variable

In this paper a parameter observer and a synchronization controller are designed to synchronize unknown chaotic systems with diverse structures. Based on stability theory the structures of the observer and the controller are presented. The unknown Coullet system and Rossler system are taken for examples to demonstrate that the method is effective and feasible. The artificial simulation results show that global synchronization between the unknown Coullet system and the Rossler system can be achieved by a single driving variable with co-operation of the observer and the controller, and all parameters of the Coullet system can be identified at the same time.     

Start-stop control strategies for heat recovery in multi-zone water-loop heat pump systems

A study is made to determine the energy saving potential of a start—stop controlled water-loop heat pump (WLHP) system. The physical model consists of individual heat pumps for each zone, a two-pipe water-loop system (with and without a storage tank), a boiler and an evaporative cooler. The overall system consists of four input energy controllers and an equal number of mass flow rate controllers. A simple start-stop control strategy for the system is developed. Results showing the typical daily operation of the system under changing heating and cooling loads are presented. A method for selecting the appropriate limits for loop water temperature which results in energy savings is given.     

Network-based modelling and active control for offshore steel jacket platform with TMD mechanisms

The network-based modelling and active control for an offshore steel jacket platform with an active tuned mass damper mechanism is investigated. A network-based dynamic model of the offshore platform is first established. A network-based state feedback control scheme is developed. Under this scheme, the corresponding closed-loop system is modelled by a system with an artificial interval time-varying delay. Then, a delay-dependent stability criterion for the corresponding closed-loop system is derived. Based on this stability criterion, a sufficient condition on the existence of the network-based controller is obtained. It is found through simulation results that (i) both the oscillation amplitudes of the offshore platform and the required control force under the network-based state feedback controller are smaller than those under the nonlinear controller and the dynamic output feedback controller; (ii) the oscillation amplitudes of the offshore steel jacket platform under the network-based feedback controller are almost the same as the ones under the integral sliding mode controller, while the required control force by the former is smaller than the one by the latter.     

Input shaping and variable structure control for simultaneous precision positioning and vibration reduction of flexible spacecraft with saturation compensation

This paper treats the question of simultaneous robust attitude control and vibration suppression of orbiting spacecraft with flexible appendages. The spacecraft consists of a rigid body and two flexible appendages and the finite dimensional representation of the flexible spacecraft is assumed to be of arbitrary order. Robust nonlinear variable structure control (VSC) strategy integrated with input shaping technique is concerned for the pitch angle control and elastic vibration suppression under actuator saturation limit. More specially, the input shaper is implemented outside of the feedback loop, which is designed for the reference model and achieves the exact elimination of residual vibration; while for the feedback loop, the variable structure controller is designed to make the closed-loop system behave like the reference model with the input shaper in the presence of parametric uncertainty, external disturbances and actuator saturation. To prevent the presence of input saturation from destroying the system performance, a saturation compensator is designed as well for the variable structure attitude control system. For the synthesis of the attitude controller, only the pitch angel and its derivative are used. Simulation results are presented which show that in the closed loop, pitch angel control and elastic mode stabilization are accomplished in spite of uncertainty and external disturbance.     

不确定自催化反应扩散时空混沌系统的延时同步

设计了一种延迟同步控制器实现了时空混沌系统之间的同步控制.基于Lyapunov稳定性定理,确定了延迟同步控制器的结构以及系统状态变量之间的误差方程.以自催化反应扩散时空混沌系统为例,仿真模拟验证了该控制器的有效性.进一步设计了参量辨识器,对不确定自催化反应扩散时空混沌系统中的参量进行了有效辨识.通过研究有界噪声影响下系统的同步效果,表明该同步方法具有较好的抗干扰能力. 关键词： 时空混沌 延时同步 参量辨识 有界噪声     

直膨式空调人工神经网络在线自适应控制器应用研究

直接膨胀式空调系统人工神经网络控制器已经有了一些研究成果,为了解决控制器控制范围和精度的问题,引入在线自适应控制系统。该控制器的控制能力测试采用直接膨胀式空调系统实验装置进行。试验结果表明,基于人工神经网络动态模型的在线自适应控制器进行训练的前提下,该控制器能够将室内空气的干球和湿球温度控制在一定范围内,具有较高的控制精度。     

Nonlinear suboptimal tracking control of spacecraft approaching a tumbling target

We investigate the close-range relative motion and control of a spacecraft approaching a tumbling target. Unlike the traditional rigid-body dynamics with translation and rotation about the center of mass(CM), the kinematic coupling between translation and rotation is taken into consideration to directly describe the motion of the spacecraft's sensors or devices which are not coincident with the CM. Thus, a kinematically coupled 6 degrees-of-freedom(DOF) relative motion model for the instrument(feature point) is set up. To make the chaser spacecraft's feature point track the target's, an optimal tracking problem is defined and a control law with a feedback-feedforward structure is designed. With quasi-linearization of the nonlinear dynamical system, the feedforward term is computed from a specified constraint about the dynamical system and the reference model, and the feedback action is derived starting from the state-dependent Ricca equation(SDRE). The proposed controller is compared with an existing suboptimal tracking controller, and numerical simulations are presented to illustrate the effectiveness and superiority of the proposed method.     

一种新型自激发布里渊掺铒光纤激光器

利用级联的受激布里渊效应,自激发布里渊掺铒光纤激光器可以实现常温下的多波长激光输出。通过在自激发掺铒光纤激光器中引入一个高双折射萨尼亚克(Sagnac)环形滤波器,调节萨尼亚克环形滤波器的偏振控制器(PC),实现了可调谐多波长输出,同时在实验中观测到双布里渊多波长带的现象。研究了这种光纤激光器中萨尼亚克环形滤波器的带宽和980 nm抽运光功率对输出波长数的影响,在萨尼亚克环形滤波器的带宽为83.3 nm以及980 nm抽运光功率为260 mW时,得到了52个间隔为0.088 nm的多波长激光输出。     

基于DSP的直线感应电机模糊矢量控制系统研究

针对直线感应电机强耦合、多变量、非线性、时变的控制特点,将模糊控制策略应用到转差频率直线感应电机矢量控制系统中。建立了计及端部效应的直线感应电机等效数学模型,设计了基于DSP的直线感应电机模糊控制系统的软硬件,采用磁链开环、速度和电流闭环的矢量控制系统,对速度模糊控制器进行了设计。对直线感应电机在起动和负载情况下的动态特性进行了仿真实验,结果表明：采用模糊控制实现的直线感应电机转差频率矢量控制系统比具有基本数学模型的传统PI控制系统具有更强的鲁棒性。     

基于模型的预警无人机飞控系统开发与验证

为应对城市低空预警任务对固定翼无人机飞控系统自主飞行需求,采用基于模型设计方法完成无人机飞控系统开发与验证。开发过程中以飞控算法模型为中心,逐级开展飞控算法模型设计与数学仿真、算法快速原型验证以及飞控系统硬件产品实现。飞控算法模型在Matlab/Simulink平台中完成了构建及数学仿真验证,结合Higale系统提供的实时仿真环境完成算法快速原型验证,基于代码自动生成方式将算法模型自动转换为可在DSP中运行的实时代码,下载到飞控计算机中,进行硬件在回路仿真验证,并进一步进行整机地面验证。经过实践,所提出的飞控系统开发与验证流程可以将系统设计中存在的问题缺陷在开发早期暴露出来并及时修正,保证了系统研制进度、成本和品质。     

An all-optical buffer based on polarization rotation in an EAM

A theoretical model of the refractive index changes of the TE and TM modes in an electro-absorption modulator （EAM） is deduced. The photon absorption and refractive index changes are analyzed numerically. The influence of pump intensity on the phase difference between the TE and TM modes is studied. The polarization rotation effect is obtained in the EAM, and a novel all-optical fiber loop buffer is designed.     

Partial eigenvalue assignment for structural damage mitigation

In partial eigenvalue assignment, not all eigenvalues of the open loop system matrix are modified through a multiple input state or output feedback controller. This freedom available to assign selected eigenvalues of the closed loop system matrix has been widely used in design contexts such as to eliminate spillover effects in structural control problems. Similar approach is also required to modify damping and/or stiffness characteristics in selected eigenmodes of a damaged structure. When an external force acts on the damaged structure, partial eigenvalue assignment in this fashion will attempt to use minimal control effort and keep the structure active with safe operation. In this paper, a new approach to partial eigenvalue assignment and its application to structural damage mitigation are presented. A three mass spring-damper model with damage in one of the springs is illustrated with damping modifications at specific eigenmodes. The procedure is repeated for a second example, which is a cantilever beam modeled using two inputs and 10 state variables.     

Design of an active suspension to suppress the horizontal vibrations of a spray boom

Spray-boom vibrations are one of the main causes of a non-homogeneous distribution of agro-chemicals. Yawing and jolting motions of the boom are most critical. A horizontal active suspension, reducing yawing and jolting is designed. The use of special and consequently expensive equipment hampers the breakthrough of active suspensions. Therefore the proposed active suspension is built from standard hydraulic equipment, suited for mobile applications. Coulomb friction and asymmetric behaviour introduces considerable non-linearities, complicating the derivation of a linear model and controller design. It is explained how to identify a model, approximating in the best-possible way the general linear behaviour of the system. By the H^∞ methodology and an iterative procedure, introduced in this paper, non-linearities are taken into account in the controller design without increasing the controller dimensions. The resulting controller is stable and shows good performance.     

Booster stage adaptive backstepping tracking control for interceptor

An adaptive backstepping tracking controller in the presence of uncertain parameters and external disturbance is designed for the thrust vector-controlled interceptor during its booster stage. The dynamic equation is formulated into a parametric-strict-feedback form under reasonable assumption. The controller design is decomposed into two loops, which are aerodynamic angle loop and angular rate loop. The whole closed system is proved to converge into a compact set asymptotically by employing feedback control laws and adaptive estimate laws designed in this paper. The controller proposed here has two main advantages. First, it can deal with the disturbances whose bounds have the expression of all system states. Second, there is no chattering in the tracking process by using continuous hyperbolic tangent function in place of sign function. Simulation results demonstrate that the proposed method in this paper not only afford strong capability but also achieve a fast and accurate response of resistance to parameters uncertainty and external disturbances.     

考虑模型不确定性和时延的静止无功补偿器自适应滑膜控制器设计

静止无功补偿器(static var compensator,SVC)不仅可以为电力系统提供无功支撑、稳定电压,其附加控制还可以有效提高系统暂态稳定性,但SVC模型参数的不确定性以及广域测量信号时延等外部干扰给附加控制器的设计带来很大的难度.提出了一种基于自适应滑模变结构理论的SVC鲁棒控制器设计方法,所设计控制器能有效提高系统暂态稳定性,并且其对于模型不确定性以及时延有较好的鲁棒性.首先根据区域惯量中心的运动方程建立了包含SVC的电力系统模型;然后将滑模变结构理论应用于电力系统模型中,求得SVC附加控制律,并通过自适应律优化控制器参数;最后通过四机两区域系统以及IEEE9节点系统对SVC控制器效果进行了仿真验证.结果表明,SVC自适应滑模控制器可以有效提升系统暂态稳定性,并且其性能优于传统的线性控制方法.