展览

张观鹿个展空间站中国・北京2024年5月18日-2024年6月30日《惊奇的房间》是张观鹿最新创作的与艺术家工作室有关的系列作品。工作室对于艺术家来说有着非常重要的意义,这与艺术家个人经历和喜好有所不同,也是个人成就和身份的象征。在张观鹿的“工作室”中,有经过他精心编排的保罗·塞尚、一生画瓶子的求索者莫兰迪、墨西哥传奇女艺术家弗里达、图伊曼斯和米罗……张观鹿从他们的作品中窥探出线索创造了“惊奇”的工作室房间。这并不是模仿,这全然来自于艺术史和知识系统,“适当引用,恰当用典”。

Tension Active Disturbance Rejection Control of Automatic Yarn Splicing Robots for Ring Spinning

Automatic splicing of interrupted yarns in ring spinning has always been a problem in the industry.Factors such as low yarn strengths and environmental influence on yarn tensions make it difficult to control the yarn tension during the robotic splicing process.The purpose of this research is to design active disturbance rejection control(ADRC)for a third-order nonlinear tension system subject to external disturbances.Firstly,a third-order extended state observer(ESO)is designed to achieve the suppression and the compensation of the internal modeling error and the external disturbances of the system.Secondly,the adaptive gain error feedback control and the filtering process are designed to reduce the influence of sensor noise on the disturbance observation.Finally,the tension control during the splicing process is simulated and experimented,and the experiments show that the method has good robustness in the tension tracking task under a dynamic environment,which verifies the effectiveness of the method.

状物类说明性课文教什么——“关注文体,聚焦表达”阅读教学主张观照下的教材解读

这次,我们呈现的三篇课文都属于状物类课文,依据《语文课程标准（2011年版）》规定,在文体样式上属于说明性文章。而对于说明性文章,课标提出：阅读说明性文章,能抓住要点,了解文章的基本说明方法。在小学,我们不提文章体裁。即使到初中,课标也只是要求：能够区分写实作品与虚构作品,了解诗歌、

正整数集N的一类可加划分

对于一个给定的递推正整数序列U={u_m},其中,我们证明由这个U所形成的正整数集N的可加划分恰有两个。

“品效合一”广点通

在对的时间,通过对的媒介组合策略,用对的方式,讲给对的人听。2015年,中国移动互联网用户规模接近9亿,且持续增长,其中4G用户达1.62亿。移动端的迅速崛起,带来了媒介的碎片化,伴随着多设备终端、多入口的出现,消费者的时间被切割在不同的屏幕——白天上班用电脑、路上看手机、回到家玩平板……这也就意味着,广告主需要在不同屏幕上用不同的方式和频率跟消费者传达合适的信息,营销向多屏转换,消费者只对＂与自己相关的内容＂有共鸣,个性化消费时代来临。

Fuzzy disturbance rejection predictive control of ultra-supercritical once-through boiler-turbine unit

In order to overcome the wide-range load tracking and unknown disturbance issues of an ultra-supercritical boiler- turbine unit, a fuzzy disturbance rejection predictive control approach is proposed using the techniques of fuzzy scheduling, model predictive control and extended state observer. Local state-space models are established on the basis of nonlinearity analysis and subspace identification. To eiJiance thedisturbance rejection capability of the controller, a extended state observer is employed to estimate unnown disturbances and model mismatches. The disturbance estimation ennaced local predictive controllers ae subsequently devised based on the local models, the performance of which is further strengthened by incorporating the fuzzy scheduling technique. The simulation results verify the merits of the proposed strategy in achieving satisfactory wide-range load tracking ad disturbance rejection performance.

吴其昌《宋代学生干政运动考》微瑕两例

近人感于时艰,多述历代志士事迹以砥砺气节,故其为文原不必拘小节(如黄现瑶、吴景贤、沈忱农、翦伯赞等关于陈东文,请参拙文<陈东与靖康学潮>,<史林>2000年第2期).吴其昌<宋代学生干政运动考>(<清华学报>1926年第3卷第2期)为一学术作品,旨趣不同.其作在相关文字中出产最早,但晚出诸作并未能青出于蓝,三、四十年代至有剿袭此文而成篇者.不过,此文也有智者之失,在此谨举二例以供补白.

Performance of grouts for post-tensioned prestressed structures

New high performance grouts with high volume stability and good fluidity were prepared with Portland cement and a multifunctional admixture (MFA). The theological characteristics and mechanical performance of the grouts were investigated. The addition of MFA effectively improves the pseudo-plasticity of the grout. The Ma cone flow time decreases obviously, and the bleeding rate tends to be zero. The deformation behaviors of fresh mixture and hardened grout are systematically studied. Mercury injection method (MIP), scanning electron microscopy (SEM) and X-ray diffractory analysis experiments are used to analyze the microstructure evolution of the grouts, which manifests that the co-action of the early bubble reaction and the latter ettringite crystallization ensure the volume stability throughout the whole hydration process and result in refined pore structure of the grout.

全国中等林校森林经理教学研讨班在宁举办

在林业部教育宣传司的支持下,由中等林校《森林经理学》课题组主办,于1991年9月2日至19日,在南京林业干部学校举办全国中等林校《森林经理学》教学研讨班,共有25所林校34名学员参加,其中,30岁以下的年青教师占70%。会议期间,林业部教育宣传司张观礼司长看望了大家,并讲了话。要求大家认真研讨,互相学习,返校后,不但要把《森林经理学》这门课教好,还要在育人方面下功夫。

伍博士和他的象棋生活(二)

我看了《中国象棋四明弈派研究》,同样大开了眼界。从这本书里,不仅能了解《吴著梅花谱》、《心武残编》等著作和历来名谱的评述,还能对历代象棋流派有个大致的认识。而在近现代史上,四明弈派的确是重要的一个分支,其特有的棋理棋艺、棋风棋德,具有很高的学术价值与文化教育价值。至于四明弈派中出类拔萃的人物,也是层出不穷的。早在上世纪20年代,就有张观云、

Simulation on model predictive control for PMSM drive system based on double extended state observer

A novel double extended state observer(DESO)based on model predictive torque control(MPTC)strategy is developed for three-phase permanent magnet synchronous motor(PMSM)drive system without current sensor.In general,to achieve high-precision control,two-phase current sensors are necessary for successful implementation of MPTC.For this purpose,two ESOs are used to estimate q-axis current and stator resistance respectively,and then based on this,d-axis current is estimated.Moreover,to reduce torque and flux ripple and to improve the performance of the torque and speed,MPTC strategy is designed.The simulation results validate the feasibility and effectiveness of the proposed scheme.

Differential geometric guidance command with finite time convergence using extended state observer

For improving the performance of differential geometric guidance command(DGGC), a new formation of this guidance law is proposed, which can guarantee the finite time convergence(FTC) of the line of sight(LOS) rate to zero or its neighborhood against maneuvering targets in three-dimensional(3D) space. The extended state observer(ESO) is employed to estimate the target acceleration, which makes the new DGGC more applicable to practical interception scenarios. Finally, the effectiveness of this newly proposed guidance command is demonstrated by the numerical simulation results.

Double ESOs-based field-oriented control for PMSM drive system with current sensorless

A novel double extended state observers(ESOs)-based field-oriented control(FOC)strategy is developed for three-phase permanent magnet synchronous motor(PMSM)drive systems without any phase current sensor.In principle,two current sensors are essential parts of the drive system for implementation of the feedback to achieve high accuracy control.For this purpose,the double ESOs are created to provide feedback stator currents instead of actual current sensors.The first one of the double ESOs is designed to estimate the benchmark value of q-axis stator current,which is a primary premise;While the second is designed to estimate real-time stator currents of d-axis and q-axis simultaneously.The resultant double ESOs can rapidly and accurately give estimation of the actual currents of a-axis,b-axis and c-axis,and the synthesized double ESOs-based FOC strategy for PMSM drive system without any current sensors has satisfactory control performance and strong robustness.Numerical experiments validate the feasibility and effectiveness of the proposed scheme.

Research on improved active disturbance rejection control of continuous rotary motor electro-hydraulic servo system

In order to meet the precision requirements and tracking performance of the continuous rotary motor electro-hydraulic servo system under unknown strong non-linear and uncertain strong disturbance factors,such as dynamic uncertainty and parameter perturbation,an improved active disturbance rejection control(ADRC)strategy was proposed.The state space model of the fifth order closed-loop system was established based on the principle of valve-controlled hydraulic motor.Then the three parts of ADRC were improved by parameter perturbation and external disturbance;the fast tracking differentiator was introduced into linear and non-linear combinations;the nonlinear state error feedback was proposed using synovial control;the extended state observer was determined by nonlinear compensation.In addition,the grey wolf algorithm was used to set the parameters of the three parts.The simulation and experimental results show that the improved ADRC can realize the system frequency 12 Hz when the tracking accuracy and response speed meet the requirements of double ten indexes,which lay foundation for the motor application.

Dynamic Positioning System Based on Active Disturbance Rejection Technology

A dynamically positioned vessel, by the International Maritime Organization （IMO） and the certifying class societies （DNV, ABS, LR, etc.）, is defined as a vessel that maintains its position and heading （fixed location or pre-determined track） exclu- sively by means of active thrusters. The development of control technology promotes the upgrading of dynamic positioning （DP） systems. Today there are two different DP systems solutions available on the market： DP system based on PID regulator and that based on model-based control. Both systems have limited disturbance rejection capability due to their design principle. In this paper, a new DP system solution is proposed based on Active Dis^n＇bance Rejection Control （ADRC） technology. This technology is com- posed of Tracking-Differentiator （TD）, Extended State Observer （ESO） and Nonlinear Feedback Combination. On one hand, both TD and ESO can act as filters and can be used in place of conventional filters; on the other hand, the total disturbance of the system can be estimated and compensated by ESO, which therefore enhances the system＇s disturbance rejection capability. This technology＇s advantages over other methods lie in two aspects： 1） This method itself can not only achieve control objectives but also filter noisy measurements without other specialized filters; 2） This method offers a new useful approach to suppress the ocean disturbance. The simulation results demonstrate the effectiveness of the proposed method.

Active disturbance rejection control FCS-MPC strategy based on ESO of PMSM system

In order to improve the control performance of three-phase permanent magnet synchronous motor(PMSM)system,an active disturbance rejection finite control set-mode predictive control(FCS-MPC)strategy based on improved extended state observer(ESO)is proposed in this paper.ESO is designed based on the arc-hyperbolic sine function to obtain estimations of rotating speed and back electromotive force(EMF)term of motor speed.Active disturbance rejection control(ADRC)is applied as speed controller.The proposed FCS-MPC strategy aims to reduce the electromagnetic torque ripple and the complexity and calculation of the algorithm.Compared with the FCS-MPC strategy based on PI controller,the constructed control strategy can guarantee the reliable and stable operation of PMSM system,and has good speed tracking,anti-interference ability and robustness.

Compound control for speed and tension multivariable coupling system of reversible cold strip mill

To weaken the nonlinear coupling influence among the variables in the speed and tension system of reversible cold strip mill, a compound control(CC) strategy based on invariance principle was proposed. Firstly, invariance principle was used to realize static decoupling between the speed and tension of reversible cold strip mill. Then, considering the influence caused by the time variation of steel coil radius and rotational inertia of the left and right coilers, as well as the uncertainties, a CC strategy that is composed of extended state observer(ESO) and global sliding mode control(GSMC) with backstepping adaptive was proposed,which further realized dynamic decoupling and coordination control for the speed and tension system. Theoretical analysis shows that the resulting closed-loop system is global bounded stable. Finally, the simulation was carried out on the speed and tension system of a 1422 mm reversible cold strip mill by using the actual data, and through the comparison of the other control strategies, validity of the proposed CC strategy was shown by the results.

A novel MPTC sensorless control strategy for ANFTSMC with ESO to control PMSM

Aiming at the problem that the traditional control strategy of permanent magnet synchronous motor(PMSM)for electric vehicles has low control performance,a novel adaptive non-singular fast terminal sliding mode control(ANFTSMC)model predictive torque control(MPTC)strategy is proposed.A new adaptive exponential approach rate is designed,and the traditional switching function sgn()is replaced by the hyperbolic tangent function tanh().A new ANFTSMC with extended state observer(ESO)is constructed as the speed regulator of the system,and ESO can observe disturbances.This improved method weakens chattering and improves the robustness of the system.To realize sensorless control of the speed control system,an ESO speed observer based on tanh(Fal)is constructed.Compared with the traditional ESO based on Fal function,the observation error is smaller,and the observation accuracy is higher.Finally,aiming at the model predictive torque control strategy used,a new objective function construction method is proposed,which avoids the design of weight coefficient,and the traditional voltage vector selection method is improved and optimized,which reduces the calculation amount of the algorithm.

Expansive Fiscal Policies and Supply-Demand Imbalance： A Chicken and Egg Problem？

It is generally accepted that governments favor expansive fiscal policies to address an economic scenario in which supply exceeds demand. In other words, economic imbalance is regarded as the cause of the problem and fiscal expansion as the result. However, this paper posits that China＇s expansive fiscal policies may also be a major cause of its economic imbalance, and that fiscal expansion and economic imbalance create cumulative causation. Specifically, China＇s tax system, characterized by a regressive commodity tax, intensifies constraints on domestic consumption while distributing a large proportion of national income to government and enterprises; supply-demand imbalance prompts the government to expand fiscal expenditures and increase taxes, which further exacerbates this imbalance. Thus, even as the country faces a macroeconomic imbalance, the strong measures it adopts in response may stimulate economic growth in the short term, but in the long term, they may do exactly the opposite and create the next economic crisis.