ON DE FINETTI'S OPTIMAL IMPULSE DIVIDEND CONTROL PROBLEM UNDER CHAPTER 11 BANKRUPTCY

Motivated by recent advances made in the study of dividend control and risk management problems involving the U.S.bankruptcy code,in this paper we follow[44]to revisit the De Finetti dividend control problem under the reorganization process and the regulator's intervention documented in U.S.Chapter 11 bankruptcy.We do this by further accommodating the fixed transaction costs on dividends to imitate the real-world procedure of dividend payments.Incorporating the fixed transaction costs transforms the targeting optimal dividend problem into an impulse control problem rather than a singular control problem,and hence computations and proofs that are distinct from[44]are needed.To account for the financial stress that is due to the more subtle concept of Chapter 11 bankruptcy,the surplus process after dividends is driven by a piece-wise spectrally negative Lévy process with endogenous regime switching.Some explicit expressions of the expected net present values under a double barrier dividend strategy,new to the literature,are established in terms of scale functions.With the help of these expressions,we are able to characterize the optimal strategy among the set of admissible double barrier dividend strategies.When the tail of the Lévy measure is log-convex,this optimal double barrier dividend strategy is then verified as the optimal dividend strategy,solving our optimal impulse control problem.

两阶段pH控制和碳氮源协同补加促进谷氨酸棒杆菌高产L-谷氨酰胺

为提高谷氨酸棒杆菌发酵产L-谷氨酰胺产量、糖酸转化率、生产强度等技术指标,该文通过响应面法优化了摇瓶发酵培养基中葡萄糖、(NH_(4))_(2)SO_(4)和玉米浆含量,并利用50 L发酵罐进行分批发酵,构建了菌体生长、底物消耗和产物生成动力学模型,进而在50 L发酵罐中采用两阶段控制pH策略,并通过补加葡萄糖和(NH_(4))_(2)SO_(4),协同控制发酵液中碳氮源浓度,促进菌体高效合成L-谷氨酰胺。结果表明,优化后发酵培养基中葡萄糖、(NH_(4))_(2)SO_(4)和玉米浆含量分别为167、61、31 g/L,摇瓶发酵L-谷氨酰胺产量达到38.13 g/L,较优化前提高了34.12%;50 L发酵罐分批发酵80 h后L-谷氨酰胺产量达42.06 g/L,糖酸转化率达到25.85%,生产强度为0.53 g/(L·h);在50 L发酵罐中基于两阶段pH控制的碳氮源协同补加策略,显著促进了谷氨酸棒杆菌高产L-谷氨酰胺,发酵周期缩短至52 h,L-谷氨酰胺产量达68.01 g/L,糖酸转化率达33.93%,生产强度为1.31 g/(L·h)。该研究对促进L-谷氨酰胺的工业化生产具有重要参考价值。

R^(1+1)中Maxwell-Chern-Simons-Higgs模型解的L^(∞)估计

用能量守恒估计和特征线估计的方法解决(1+1)维Maxwell-Chern-Simons-Higgs模型解的Sobolev范数增长性估计问题,给出模型有限能量解的一阶导数的L^(∞)估计,并通过改进指数增长得到解的H^(2)范数的多项式增长.

Parameters Optimization and Performance Evaluation of the Tuned Inerter Damper for the Seismic Protection of Adjacent Building Structures

In order to improve the seismic performance of adjacent buildings,two types of tuned inerter damper(TID)damping systems for adjacent buildings are proposed,which are composed of springs,inerter devices and dampers in serial or in parallel.The dynamic equations of TID adjacent building damping systems were derived,and the H2 norm criterion was used to optimize and adjust them,so that the system had the optimum damping performance under white noise random excitation.Taking TID frequency ratio and damping ratio as optimization parameters,the optimum analytical solutions of the displacement frequency response of the undamped structure under white noise excitation were obtained.The results showed that compared with the classic TMD,TID could obtain a better damping effect in the adjacent buildings.Comparing the TIDs composed of serial or parallel,it was found that the parallel TIDs had more significant advantages in controlling the peak displacement frequency response,while the H2 norm of the displacement frequency response of the damping system under the coupling of serial TID was smaller.Taking the adjacent building composed of two ten-story frame structures as an example,the displacement and energy collection time history analysis of the adjacent building coupled with the optimum design parameter TIDs were carried out.It was found that TID had a better damping effect in the full-time range compared with the classic TMD.This paper also studied the potential power of TID in adjacent buildings,which can be converted into available power resources during earthquakes.

Lipschitz非线性离散系统基于观测器的鲁棒镇定控制设计

本文研究Lipschitz非线性离散时间系统的基于观测器的鲁棒镇定控制问题.首先,针对Lipschitz非线性离散系统,应用微分中值定理和线性参变系统理论,以线性矩阵不等式(LMI)的形式给出基于观测器的鲁棒镇定控制设计的充分条件.随后,将设计结果进一步推广,针对含干扰的Lipschitz非线性离散系统进行H∞性能分析,实现了基于观测器的鲁棒H∞镇定控制,同时给出观测器增益矩阵和控制器增益矩阵的一步求解算法.最后,通过两个数值例子验证了所提方法的有效性.

HB-Continuous Mappings in L-Topological Space

In this paper, we introduce and study the notion of HB-closed sets in L-topological space. Then, HB-convergence theory for L-molecular nets and L-ideals is established in terms of HB-closedness. Finally, we give a new definition of fuzzy H-continuous [1] which is called HB-continuity on the basis of the notion of H-bounded L-subsets in L-topological space. Then we give characterizations and properties by making use of HB-converges theory of L-molecular nets and L-ideals.

Active Cancelation of Acoustic Noise in Waveguides by Standard Control Task Decision Usage

Cybernetic decision variants were analyzed in order to use for physical task of active noise cancelation. 10 dB mean active noise cancellation is demonstrated in two decades frequency band by usage of cybernetic decision for acoustical duct physical scale model. The used decision was found on minimization of acoustical field power transfer function from the beginning of waveguide to their end.

H∞ Control for Externally Excited Building Structures with Active Mass Damper under Actuator Saturation

This paper investigates the application of active mass dampers to mitigate the vibrations of building structures subjected to unknown external excitations under controller saturation conditions. By utilizing an H∞ control strategy, the optimal state feedback controller is derived by solving the linear matrix inequality problem for controller saturation. Case studies show that the proposed controller is capable of stabilizing the closed-loop system with good control performance and effectively suppressing vibrations in building structures under unknown external excitation. When compared to controllers that do not consider saturation, the proposed controller requires lower gain and results in reduced energy consumption. The research findings provide valuable insights for addressing real-world building structure control problems, contributing to both theoretical significance and practical applications.

Finite-Time H∞ Control of Switched Nonlinear Systems under State-Dependent Switching

This paper investigates the finite-time H∞ control problem of switched nonlinear systems via state-dependent switching and state feedback control. Unlike the existing approach based on time-dependent switching strategy, in which the switching instants must be given in advance, the state-dependent switching strategy is used to design switching signals. Based on multiple Lyapunov-like functions method, several criteria for switched nonlinear systems to be finite-time H∞ control are derived. Finally, a numerical example with simulation results is provided to show the validity of the conclusions.

具有介质访问约束的网络化控制系统H∞状态估计

研究了一类存在介质访问约束和信号量化的网络化控制系统的H∞状态估计问题。首先,考虑到介质访问约束和信号量化的影响,将信号量化误差转化为扇形有界的不确定性,对由于访问约束而未获得网络传输的系统输出采用加权补偿策略,根据网络介质的随机访问机制将网络化系统建模为具有不确定性的马尔可夫跳跃系统。然后,在此基础上借助李雅普诺夫稳定性理论和H∞性能约束条件,利用线性矩阵不等式(linear matrix inequality,LMI)方法给出状态估计器存在的充分条件,所设计的状态估计器使得估计误差系统渐近稳定且具有给定的H∞性能。最后,通过仿真实例验证了该设计方法的有效性。

含时滞的不确定性交直流微电网直流母线电压H_∞控制

针对含通信网络延时的不确定性交直流微电网的直流母线电压稳定问题,提出了一种将状态空间法和阻抗分析法相融合的方法,构建具有时滞的范数有界不确定交直流微电网模型。基于系统鲁棒二次稳定的求解,获得了满足H_∞控制性能的时滞无关型状态反馈控制器的条件。然后应用S-procedure定理,提出一种降低时滞依赖型Lyapunov方法的泛函构造难度且无须再次求导的方法,引用Wirtinger积分不等式和自由矩阵的积分不等式,得到时滞依赖型的H_∞控制器。仿真分析验证了所提控制方法能在一定的通信延时约束下抑制不确定参数对直流母线电压的影响。

带扰动补偿的永磁同步电机鲁棒H∞控制

为了提高永磁同步电机调速系统的抗干扰能力,提出了一种鲁棒H∞控制方法。首先,根据鲁棒H∞控制原理,提出了永磁同步电机H∞速度控制设计方法,并介绍了求解方法。设计加权函数时考虑了跟踪性能、干扰抑制、输出限制和模型不确定性。通过伯德图详细说明了性能加权函数对动态性能的影响,并给出了加权函数的设计方法。然后,在考虑参数不确定性和未建模动态的情况下,为进一步提高系统的抗干扰能力,通过Luenberger扰动观测器将扰动作为前馈补偿观测,并将其反馈到速度控制器中,以加速动态响应,增强对扰动的抑制能力。最后,通过试验对比了传统比例积分控制器、H∞速度控制器和所提的复合速度控制器,试验结果验证了所提复合速度控制器的有效性。

罕见EGFR L833V/H835L复合突变的肺腺癌患者1例及文献回顾

表皮生长因子受体(epidermal growth factor receptor,EGFR)突变是非小细胞肺癌(non-small cell lung cancer,NSCLC)发生发展过程中最常见的驱动基因,其中18-21号外显子的突变常见,尤其是19号外显子的缺失和21号外显子L858R点突变最为常见,但是EGFR L833V/H835L罕见基因复合突变的发生率非常低,患者数量很少,相关临床数据和治疗方法的证据也不足。部分EGFR-酪氨酸激酶抑制剂(EGFR-tyrosine kinase inhibitors,EGFR-TKIs)在治疗伴有罕见基因突变的肺癌患者方面同样具有良好疗效。本文报道了1例携带EGFR L833V/H835L罕见基因复合突变的NSCLC患者,在给予阿法替尼治疗5个月后,计算机断层扫描(computed tomography,CT)显示肺部病灶缩小,患者对阿法替尼联合安罗替尼治疗反应良好。同时,我们还对以往报道的EGFR L833V/H835L罕见基因复合突变的NSCLC患者进行了整理,总结了该类患者的特点及应用不同种类EGFR-TKIs治疗的效果。

H型钢连接L形方钢管混凝土组合异形柱偏压性能研究

为提升方钢管混凝土组合异形柱加工制作的便捷性与精度、减小焊接对板件变形的影响,提出了新型H型钢连接L形方钢管混凝土组合异形柱(LCFST-H),并研究其偏压荷载下的力学性能。设计了两个试件进行偏压加载试验,建立计算模型开展有限元分析。在验证有限元模型准确性的基础上,分析了H型钢连接板尺寸、方钢管截面尺寸、柱高度等参数对组合异形柱偏压受力性能的影响。结果表明:构件破坏形式为整体弯曲失稳与局部屈曲破坏,达到极限承载力后,单肢柱之间仍能通过H型钢连接板很好地协同工作,具备一定承载能力,体现出较高的延性性能。方钢管截面尺寸和柱高度对其偏压性能影响较大。结合相关规范,给出了H型钢连接L形方钢管混凝土组合异形柱单向偏压承载力计算公式,公式计算结果与有限元结果吻合较好。

过表达组蛋白甲基转移酶ASH1L对牛卵丘细胞增殖和凋亡的影响

旨在探究缺失的、小的、同源异形1(absent,small,or homeotic 1-like,ASH1L)过表达对牛卵丘细胞(cumulus cells,CCs)增殖和凋亡的影响。本研究将牛ASH1L SET结构域的cDNA序列克隆到pcDNA3.1上,构建牛ASH1L过表达载体;以导入pcDNA3.1+ASH1L载体的牛CCs为过表达组(ASH1L-OE),野生型牛CCs为对照组(Control),采用免疫荧光染色检测两组细胞中ASH1L表达水平和H3K36me1/2/3甲基化水平;通过流式细胞术分析ASH1L过表达细胞的凋亡和增殖情况;采用荧光定量PCR检测两组细胞中凋亡、增殖相关基因的mRNA表达水平。以牛CCs cDNA为模板,PCR扩增获得长2487 bp的牛ASH1L SET结构域DNA片段,与pcDNA3.1载体连接;经Nhe I/Not I双酶切和测序鉴定,成功构建过表达载体pcDNA3.1+ASH1L。过表达载体转染牛CCs后,细胞中ASH 1L mRNA及其蛋白表达水平、H3K36me1/2甲基化水平均显著升高(P<0.05)。另外,ASH 1L过表达显著提高了活细胞率(91.85±1.25)%vs.(87.39±1.71)%,降低了细胞凋亡率(8.08±1.21)%vs.(12.51±1.72)%,并显著下调了凋亡基因BAX和CASPASE-3 mRNA表达水平(P<0.05),上调抗凋亡基因BCL-2 mRNA表达水平(P<0.01)。ASH 1L过表达24、36 h时,细胞增殖率、增殖相关基因PCNA、CCND 2表达水平显著升高(P<0.05)。可见,ASH 1L过表达抑制了牛CCs凋亡,诱导了细胞增殖及H3K36me1/2甲基化水平的升高,为进一步研究ASH1L对CCs生长和卵泡发育的调控提供技术和理论基础。

H_∞ Consensus Control of Discrete-Time Multi-Agent Systems Under Network Imperfections and External Disturbance

This paper presents a distributed control protocol for consensus control of multi-agent systems(MASs) under external disturbances and network imperfections, including communication delay and random packet dropout. To comply with the discrete nature of networked systems, in contrast to most of the existing work for MASs under network imperfections,the agents are modeled by discrete-time dynamics. The communication network is considered to be undirected, its delay is considered to be time-varying but bounded, and its packet dropout is modeled by a Bernoulli distributed white sequence.Sufficient conditions in terms of linear matrix inequalities(LMIs)for asymptotic mean-square consensus stability are derived under network imperfections without considering external disturbances.A desired disturbance attenuation level in the presence of both external disturbances and network imperfections is also provided.A simulation example is given to verify the effectiveness of the proposed approach in coping with network imperfection and disturbances.

Improved Hybrid Robust Control Method for the Electromechanical Actuator in Aircrafts

In the flight process of aircrafts, their electromechanical actuators（EMA） must have the ability of enduring uncertainties caused by factors such as load disturbance, the variation of work temperature and the EMA＇s nonlinearity. At present, in order to increase the EMA＇s robustness on the uncertainties, the H, control method has been applied in aircrafts. The major problems with standard H∞ control lie in the large overshoot of step response and the high orders of the controller. For the purpose of addressing the two problems, this paper investigates several kinds of robust control strategies of the EMA. A mathematical model of the EMA is first built, and then with MATLAB software a H∞ controller and an improved hybrid robust controller composed of a reduced order H∞controller and a lead compensator are designed. In order to make a scientific comparison of the control effects of H∞ controller, hybrid controller and classic proportion-integral-differential（PID） controller, a simulation research is made in respect of the open loop frequency response and the closed loop step response of the three controllers. For comparing the robustness of the three controllers, the load torque is entered as a disturbance and the disturbance response of error and control input are thus obtained. The experiments with the three controllers are also conducted. Through giving the EMA a command and a disturbance torque successively, the transient response and disturbing process of EMA are recorded. The simulation and experiment results show that with the help of the hybrid controller, the EMA not only guarantees good dynamic characteristics, but also has strong robustness of disturbance rejection. Therefore, the excogitated H∞ hybrid control method effectively solves the problem of large overshoot in dynamic response, and moderately meets the requirement of overcoming the uncertainties in the EMA of aircrafts.

Real-time Feed-forward Force Compensation for Active Magnetic Bearings System Based on H∞ Controller

There are two kinds of unbalance vibrations—force vibration and displacement vibration due to the existence of unbalance excitation in active magnetic bearings（AMB） system. And two unbalance compensation methods—closed-loop feedback and open loop feed-forward are presented to reduce the force vibration. The transfer function order of the control system directly influencing the system stability will be increased when the closed-loop method is adopted, which makes the real-time compensation not easily achieved. While the open loop method would not increase the primary transfer function order, it provides conditions for real-time compensation. But the real-time compensation signals are not easy to be obtained in the open loop method. To implement real-time force compensation, a new method is proposed to reduce the force vibration caused by the rotor unbalance on the basis of AMB active control. The method realizes real-time and on-line force auto-compensation based on H∞ controller and one novel feed-forward compensation controller, which makes the rotor rotate around its inertia axis. The time-variable feed-forward compensatory signal is provided by a modified adaptive variable step-size least mean square（VSLMS） algorithm. And the relevant least mean square（LMS） algorithm parameters are used to solve the H∞ controller weighting functions. The simulation of the new method to compensate some frequency-variable and sinusoidal signals is completed by MATLAB programming, and real-time compensation is implemented in the actual AMB experimental system. The simulation and experiment results show that the compensation scheme can improve the robust stability and the anti-interference ability of the whole AMB system by using H∞ controller to achieve close-loop control, and then real-time force unbalance compensation is implemented. The proposed research provides a new control strategy containing real-time algorithm and H∞ controller for the force compensation of AMB system. And the stability of the control system is finally improved.

Sliding mode H_∞ control for a class of uncertain nonlinear state-delayed systems

A new proportional-integral （PI） sliding surface is designed for a class of uncertain nonlinear state-delayed systems. Based on this, an adaptive sliding mode controller （ASMC） is synthesized, which guarantees the occurrence of sliding mode even when the system is undergoing parameter uncertainties and external disturbance. The resulting sliding mode has the same order as the original system, so that it becomes easy to solve the H∞ control problem by designing a memoryless H∞ state feedback controller. A delay-dependent sufficient condition is proposed in terms of linear matrix inequalities （LMIs）, which guarantees the sliding mode robust asymptotically stable and has a noise attenuation level γ in an H∞ sense. The admissible state feedback controller can be found by solving a sequential minimization problem subject to LMI constraints by applying the cone complementary linearization method. This design scheme combines the strong robustness of the sliding mode control with the H∞ norm performance. A numerical example is given to illustrate the effectiveness of the proposed scheme.

Comparative Study of Trajectory Tracking Control for Automated Vehicles via Model Predictive Control and Robust H-infinity State Feedback Control

A comparative study of model predictive control(MPC)schemes and robust Hstate feedback control(RSC)method for trajectory tracking is proposed in this paper.The main objective of this paper is to compare MPC and RSC controllers’performance in tracking predefined trajectory under different scenarios.MPC controller is designed based on the simple longitudinal-yaw-lateral motions of a single-track vehicle with a linear tire,which is an approximation of the more realistic model of a vehicle with double-track motion with a non-linear tire mode.RSC is designed on the basis of the same method as adopted for the MPC controller to achieve a fair comparison.Then,three test cases are built in CarSim-Simulink joint platform.Specifically,the verification test is used to test the tracking accuracy of MPC and RSC controller under well road conditions.Besides,the double lane change test with low road adhesion is designed to find the maximum velocity that both controllers can carry out while guaranteeing stability.Furthermore,an extreme curve test is built where the road adhesion changes suddenly,in order to test the performance of both controllers under extreme conditions.Finally,the advantages and disadvantages of MPC and RSC under different scenarios are also discussed.