基于改进Funnel控制的机械臂轨迹跟踪约束控制

针对关节柔性机械臂系统在未知输入饱和的情况下的稳态和瞬态性能约束问题,提出一种改进Funnel控制结合RBF自适应神经网络的轨迹跟踪控制方法。设计了改进的Funnel控制变量以避免控制律中的微分不可导的情况;构造了时变的瞬态性能约束函数,调节系统输出初始阶段的超调量和收敛速度;采用最小参数学习法的RBF自适应神经网络,逼近机械臂系统模型的未知函数和虚拟控制律的导数,简化了控制器的设计;通过李雅普诺夫稳定性定理,证明了闭环系统中所有变量是半全局一致最终有界的。仿真实验验证了所提方法有效性。

带有饱和的电机伺服系统非奇异终端滑模funnel控制（英文）

本文提出一种非奇异终端滑模funnel控制(NTSMFC)方法,实现带有饱和输入电机伺服系统的指定性能跟踪控制.根据中值定理,非光滑饱和函数转化为放射形式,并且应用一个简单的神经网络进行逼近和补偿.为保证跟踪误差被限制在指定的界限内,同时为避免构建复杂的barrier李雅普诺夫函数或逆函数,本文采用一个新的限制变量.然后,构建非奇异终端滑模funnel控制器保证电机伺服系统的指定跟踪性能.该方法无需事先已知输入饱和函数的界限等先验知识,且基于李雅普诺夫函数设计可以保证位置跟踪误差的收敛性,最后给出仿真对比实例证明了该方法的有效性.

Conditions Supporting Funnel Cloud Development in Alaska

The characteristics and climatology of funnel clouds in Alaska were examined using operational radiosondes, surface meteorological observations, and reanalysis data. Funnel clouds occurred under weak synoptic forcing between May and September between 11 am and 6 pm Alaska Daylight Time with a maximum occurrence in July. They occurred under Convective Available Potential Energy >500 J·kg-1 and strong low-level wind shear. Characteristic atmospheric profiles during funnel cloud events served to develop a retrieval algorithm based on similarity testing. Out of more than 129,000 soundings between 1971 and 2014, 2724, 442, and 744 profiles were similar to the profiles of observed funnel cloud events in the Interior, Alaska West Coast, and Anchorage regions. While the number of reported funnel clouds has increased since 2000, the frequency of synoptic situations favorable for such events has decreased.

基于未知系统动态估计器的柔性关节机械臂funnel控制

针对带有模型不确定和外部干扰的柔性关节机械臂,提出一种基于未知系统动态估计器的funnel控制方法。基于低通滤波器设计未知系统动态估计器,用于估计模型不确定和外部干扰,该估计器结构简单,仅有一个可调参数。构造带有时变约束边界的新型funnel变量,保证系统跟踪误差被限制在预先设定的边界内,进而改善系统瞬态性能。在此基础上,设计反演控制器,保证系统输出快速准确跟踪期望轨迹。为避免传统反演法中的“微分爆炸”问题,设计跟踪微分器逼近虚拟控制律导数。并给出数值仿真对比验证本文所提方法的有效性。

多电机驱动系统的保性能鲁棒Funnel控制

本文针对含参数不确定性的多电机驱动系统,提出一种基于最优保性能鲁棒的Funnel控制方法实现系统的规定跟踪性能.该控制方法通过构造Funnel函数对误差系统进行变换,并设计自适应反步控制器保证变换后系统的稳定性即可使跟踪误差的瞬态和稳态响应均被限制在给定的Funnel边界内.然而由于系统中存在的参数不确定性会影响系统的规定控制性能,本文在Funnel控制基础上又设计了最优保性能鲁棒控制器.它是通过将参数不确定性系统的保性能鲁棒控制问题转化为标称系统的最优控制问题,并求解新的黎卡提方程而得到的.因此所设计的控制器不但消除了参数不确定性对系统的影响并且能够使系统的性能指标达到一确定的上界.最后,对四电机驱动系统进行了仿真和实验验证,说明所提出控制方法的有效性.

输入时滞非线性系统的新型动态面Funnel控制

本文针对一类带有输入时滞的不确定非线性系统,提出了新型动态面Funnel控制方案.首先设计补偿动态变量将输入时滞系统转换成无时滞的系统,仅需在递归控制的最后一步补偿,从而优化了控制器设计过程.其次,构造Funnel函数,使系统的瞬态和稳态跟踪误差被限制在给定边界内.最后,提出新型非线性动态面控制方法,不仅避免了自适应反推控制中的“微分爆炸”问题,而且消除了边界层误差,使得系统的跟踪误差最终渐近收敛到零.理论分析表明该闭环系统的所有信号一致最终有界,仿真结果验证了该控制方案的有效性.

Spatial-temporal Characteristics of Land Subsidence Corresponding to Dynamic Groundwater Funnel in Beijing Municipality,China

Due to long-term over-exploitation of groundwater in Beijing Municipality, regional groundwater funnels have formed and land subsidence has been induced. By combining a groundwater monitoring network, GPS monitor- ing network data, radar satellite SAR data, GIS and other new technologies, a coupled process model based on the dy- namic variation of groundwater and the deformation response of land subsidence has been established. The dynamic variation of groundwater fimnels and the land subsidence response process were analyzed systematically in Beijing. Study results indicate that current groundwater funnel areas are distributed mainly in the southwest of Shunyi District, the northeast of Chaoyang District and the northwest of Tongzhou District, with an average decline rate of groundwa- ter level of 2.66 rn/yr and a maximum of 3.82 m/yr in the center of the funnels. Seasonal and interannual differences exist in the response model of land subsidence to groundwater funnels with uneven spatial and temporal distribution, where the maximum land subsidence rate was about --41.08 mm/yr and the area with a subsidence rate greater than 30 mm/yr was about 1637.29 km2. Although a consistency was revealed to exist between a groundwater funnel and the spatial distribution characteristics of the corresponding land subsidence funnel, this consistency was not perfect. The results showed that the response model of land subsidence to the dynamic variation of groundwater was more revealing when combining conventional technologies with InSAR, GIS, GPS, providing a new strategy for environmental and hydrogeological research and a scientific basis for regional land subsidence control.

Feasibility of using recycled CRT funnel glass as partial replacement of high density magnetite sand in radiation shielding concrete

The recycled cathode ray tube(CRT)funnel glass was used as replacement of magnetite sand in the concrete,and its mass replacement rates were 0,20%,40%and 60%,respectively.The flowability,apparent density and mechanical properties of the radiation shielding concrete were investigated,while itsγ-ray radiation shielding parameters such as linear and mass attenuation coefficients(μandμm,respectively),thickness values of half-value layer(hHVL)and tenth-value layer(hTVL)were obtained by theoretical calculation,experiment and Monte.Carlo N-Particle(MCNP)simulation code.The experimental results show that the flowability of the concrete increases significantly,whilst its apparent density,compressive strength and static elastic modulus decrease slightly.The calculated,simulated and experimentalμm,μ,hHVL and hTVL values of all concrete samples are very consistent at the sameγ-ray photon energy,and it is feasible to use MCNP code to simulateγ-ray radiation shielding parameters of materials.The calculated results show that in a wide range ofγ-ray photon energy,theμm value of the concrete with CRT funnel glass replacing magnetite sand is improved effectively,and its radiation shielding performances are the same as those of the control concrete(M.1).By comprehensively comparing the flowability,mechanical properties andγ-ray radiation shielding properties,the concrete samples with 20%.40%funnel glass as fine aggregate have good performances.

Corrosion mechanism of magnesia-chromite refractories by ZnO-containing fayalite slags: Effect of funnel glass addition

An efficient approach for lead extraction from waste funnel glass through the lead smelting process has been proposed. To clarify the effect of funnel glass addition on the degradation of magnesia-chromite refractories by ZnO-containing fayalite slag, the corrosion behavior of magnesia-chromite refractories in lead smelting slags with different funnel glass additions from 0wt% to 40wt% was tested. Scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDS) was used to acquire the microstructural information of the worn refractory samples. Experimental results showed that the corrosion of magnesia-chromite refractory consisted predominantly of the dissolution of MgO into slag. ZnO and FeO reacted with periclase and chromite to form (Zn,Fe,Mg)O solid solution and (Zn,Fe,Mg)(Fe,Al,Cr)2O4 spinel, respectively. With the addition of funnel glass, the solubility of MgO increased whereas ZnO levels remained stable, thereby resulting in a reduced Mg content and an elevated Zn and Fe content in the (Zn,Fe,Mg)O solid solution and the (Zn,Fe,Mg)(Fe,Al,Cr)2O4 spinel. Considering the stability of the (Zn,Fe,Mg)O solid solution layer and the penetration depth of the slag, the optimal funnel glass addition for lead smelting was found to be 20wt%.

INFLUENCES OF CASTING SPEED AND SEN DEPTH ON FLUID FLOW IN THE FUNNEL TYPE MOLD OF A THIN SLAB CASTER

In recent years, thin slab continuous casting technology has been widely used to improve the quality of the product and to reduce the cost. One of the challenges faced by this technology is to design reasonable flow patterns, which strongly affect the surface and inner properties of the final slab in the mold. With the fixed scales and complex geometrical structures of nozzle and funnel type mold, a series of numerical simulations are made to analyze the flow patterns in melt steel using finite volume method based on structured body fitted coordinate grids. The CFD （computational fluid dynamics） package is validated first using one typical case described in previously published studies, and then it is developed to study the effect of operational parameters on fluid flow in thin slab caster. Two operational parameters, casting speed and SEN （submerged entry nozzle） depth, are mainly considered for numerical analysis. On the basis of present simulations, the reasonable SEN submergence depths corresponding to different casting speeds are suggested according to fluid flow characteristics like, flow jet impingement on the narrow side of the mold, flow speed of the melt steel beneath the meniscus and the recirculation region. This is the first stage of study on the numerical analysis of the whole thin slab casting process with electromagnetic brake.

Effect of sintering temperature on microstructure and properties of glass-ceramics synthesized from waste cathode ray tubes funnel glass

Waste cathode ray tube(CRT)funnel glass(FG)is an important part in the disposal of electrical and electronic waste(e-waste).A novel approach for efficient lead extraction and glass-ceramics synthesized from waste FG through collaboratively smelting FG with coal fly ash(CFA)is proposed.Glass-ceramics materials with 40 wt%-80 wt%FG additions were produced under sintering temperatures of 900-1000℃.The microstructure and phase composition of the produced glass-ceramics were studied using X-ray diffraction(XRD)and scanning electron microscopy(SEM).The density,water absorption,Vicker hardness,chemical resistance and heavy metal leaching characteristics of the glassceramics were measured.The experimental results indicate that the samples can be crystallized at sintering temperatures of 900-1000℃.An elevated sintering temperature is favorable for enhancing the degree of crystallization,while the crystallization process is inhibited at excessively high temperatures.Increasing FG addition can lead to the transformation of the main crystalline phase from diopside to gehlenite.Well-crystallized crystals were generated in the specimens with 50 wt%-70 wt%FG additions.The samples with 40 wt%,50 wt%,60 wt%,70 wt%,80 wt%FG addition exhibit the optimal chemical and physical properties at 975,925,950,925 and 900℃,respectively.Overall results demonstrate that this study provides a feasible strategy for reliably detoxifying and reusing waste FG and CFA.

Dynamics of an Ultracold Bose Gas in Funnel-Shaped Potential

In this paper we develop a variational theory to study the dynamic properties of ultracold Bose gas ina funnel external potential.We obtain one-dimensional nonlinear equation which describes the dynamics of transversetight confined bosonic gas from three-dimension to one-dimension,and find one-dimensional s-wave scattering lengthwhich depends on the shape of transverse confining potential.If the funnel trapping potential is strong enough at zerotemperature,all transverse excitations are frozen.We find the dynamic equation which describes the Tonks-Girardeaugas and present a qualitative analysis of the experimental accessibility of the Tonks-Girardeau gas with funnel-trappedalkalic atoms.

Energy funneling and charge separation in CdS modified with dual cocatalysts for enhanced H_(2) generation

Anchoring molecular cocatalysts on semiconductors has been recognized as a general strategy to boost the charge separation efficiency required for efficient photocatalysis.However,the effect of molecular cocatalysts on energy funneling(i.e.,directional energy transfer)inside semiconductor photocatalysts has not been demonstrated yet.Here we prepared CdS nanorods with both thin and thick rods and anchored the conjugated molecules 2‐mercaptobenzimidazole(MBI)and cobalt molecular catalysts(MCoA)sequentially onto the surface of nanorods.Transient absorption measurements revealed that MBI molecules facilitated energy funneling from thin to thick rods by the electronic coupling between thin and thick nanorods,which is essentially a light‐harvesting antenna approach to enhance the charge generation efficiency in the reaction center(here the thick rods).Moreover,MBI and MCoA molecules selectively extracted photogenerated holes and electrons of CdS nanorods rapidly,leading to efficient charge separation.Consequently,CdS/MBI/MCoA displayed 15 times enhanced photocatalytic H_(2) evolution(1.65 mL)than pure CdS(0.11 mL)over 3 h of illumination.The amount of H_(2) evolution reached 60 mL over 48 h of illumination with a high turnover number of 26294 and an apparent quantum efficiency of 71%at 420 nm.This study demonstrates a novel design principle for next‐generation photocatalysts.

Research on numerical simulation of the groundwater funnels restoration in Shijiazhuang

In order to simulate the recovery of groundwater funnels under the condition of reducing groundwater abstraction, hydrogeological conditions of recoverability construction of Shijiazhuang groundwater funnel were analyzed, and a numerical simulation method was used based on the change of various parameters. The results show that the groundwater flow model can accurately reflect groundwater hydrogeological characteristics, and can guarantee the reliability of groundwater restoration prediction. The research has set up four schemes for rural water-saving, planting structure adjustment, urban reducing abstraction and integrated method. The effect of four restoration schemes on the restoration of groundwater funnels was compared with water table variations of two observation well. Comparison results show that the level changes of plan Three and Four are different from the other two kinds of exploitation and the drop trend of water table in the funnel area is flat. So we can conclude that Plan Three and Four have significant effect on the groundwater funnel restoration of Shijiazhuang.

Coupled funnel control for supersonic tailless aerial vehicle on penetrating counter air

Supersonic Tailless Aerial Vehicles(STAVs)will become an essential force in Penetrating Counter Air(PCA),but STAVs do not have the traditional horizontal and vertical tails,making pitch and yaw control difficult.The attack angle and the sideslip angle need to be limited to ensure that the engine inlet and the aerodynamic rudder at the rear of the vehicle can work properly,which is the so-called security constraints.In addition,the tracking error of the aerodynamic angle needs to be limited to achieve effective attitude control or high-accuracy tracking of trajectories,which is the so-called performance constraints.To this end,an attitude control method that meets the needs of PCA has been devised,based on constraint definition,coupled constraints handling,and control law design.Firstly,mathematical descriptions of the security constraints,performance constraints,and control constraints are given.Secondly,two treatment methods,coupled command filter and coupled funnel control are proposed for the aerodynamic angle coupled constraint problem.Finally,based on Nonlinear Dynamic Inverse(NDI)design,the coupled funnel controller is designed and validated by simulation for two typical mission scenarios,high-altitude penetration and low-altitude surprise defence.The proposed control method not only satisfies the security and performance constraints of STAV attitude control but also is highly robust.

Funneling media access control (MAC) protocol for underwater acoustic sensor networks

Due to the characteristics of the underwater acoustic channel, such as long propagation delay and low available bandwidth, the media access control (MAC) protocol designed for underwater acoustic sensor networks (UWASNs) is quite different from that for terrestrial wireless sensor networks. In this paper, we propose a MAC protocol for the UWASNs, named the funneling MAC (FMAC-U), which is a contention-based MAC protocol with a three-way handshake. The FMAC-U protocol uses an improved three-way handshake mechanism and code division multiple access (CDMA) based technology for request-to-send (RTS) signals transmitting to the sink in order that the sink can receive packets from multiple neighbors in a fixed order during each round of handshakes. The mechanism reduces the packet collisions and alleviates the funneling effect, especially alleviating the choke point of the UWASNs. Simulation results show that the proposed FMAC-U protocol achieves higher throughput, smaller packet drop ratio, lower end-to-end delay, and lower overhead of the control packet compared to the existing MAC protocols for UWASNs.

Psychological trauma of funnel chest in adolescents and the appropriate age for minimally invasive surgery repair

Background Funnel chest has a negative effect on adolescents and it has a strong effect on adolescents＇ psychological and behavior. This study aimed to investigate the psychological characteristics and factors that affect adolescents with funnel chest and to evaluate the relationship between the patients＇ age and their physiological and psychological health. We aimed to establish an age model for maximum surgery benefits for funnel chest patients to provide an objective basis for choosing surgery. Methods The study adopted a general evaluation approach to assess the risk and benefits of minimally invasive surgery for funnel chest. The funnel chest index, the Symptom Checklist-90, and the Eysenck Personality Questionnaire were used as assessment tools to observe physiological and psychological features in funnel chest patients. A sample of 234 adolescents with funnel chest was selected from a third-grade class-A hospital in Beijing. Age groups were adopted as an independent variable, and other factors in funnel chest patients were dependent variables. Results There was a significant difference in the relapse rate for funnel chest in the different age groups （X2=11.883, P=-O.008）. There was a higher relapse rate in patients of 〈10 or 〉-19 years old than in patients of 11-18 years old. There was a significant difference in the SCL-90 total score in the different age groups （F=12.538, P=-0.0001）, the patients older than 13 years had a higher score than those younger than 13 years in the SCL-90. There was a significant difference in the standard score of E （introversion/extraversion） in the different age groups （F=10.06, P=0.0001）. There was also a significance in the funnel chest index before surgery in the different psychological scales （P〈0.01）, with a higher funnel chest index score associated with more obvious psychological trauma. Age and the number of variables, including the relapse rate, SCL-90 score, standard score of E, and standard score of N in the EPQ were significantly correlated （correlation indices were 0.402, 0.623, -0.505, and 0.473, respectively, P〈0.01）. Conclusions There are higher complication rates after surgery and relapse rates when funne{ chest patients are too young or too old. There is more obvious psychological trauma in patients with a high funnel chest index. Our results indicate that the best age for surgery for funnel chest is 14-16 years.

Finite-Time Neural Funnel Control for Motor Servo Systems with Unknown Input Constraint

In this paper, a finite-time neural funnel control(FTNFC) scheme is proposed for motor servo systems with unknown input constraint. To deal with the non-smooth input saturation constraint problem, a smooth non-affine function of the control input signal is employed to approximate the saturation constraint, which is further transformed into an affine form according to the mean-value theorem. A fast terminal sliding mode manifold is constructed by using a novel funnel error variable to force the tracking error falling into a prescribe boundary within a finite time. Then, a simple sigmoid neural network is utilized to approximate the unknown system nonlinearity including the saturation.Different from the prescribed performance control(PPC), the proposed finite-time neural funnel control avoids using the inverse transformed function in the controller design, and could guarantee the prescribed tracking performance without knowing the saturation bounds in prior. The effectiveness and superior performance of the proposed method are verified by comparative simulation results.