Time-Domain Analysis of Body Freedom Flutter Based on 6DOF Equation

The reduced weight and improved efficiency of modern aeronautical structures result in a decreasing separation of frequency ranges of rigid and elastic modes.Particularly,a high-aspect-ratio flexible flying wing is prone to body freedomflutter(BFF),which is a result of coupling of the rigid body short-periodmodewith 1st wing bendingmode.Accurate prediction of the BFF characteristics is helpful to reflect the attitude changes of the vehicle intuitively and design the active flutter suppression control law.Instead of using the rigid body mode,this work simulates the rigid bodymotion of the model by using the six-degree-of-freedom(6DOF)equation.A dynamicmesh generation strategy particularly suitable for BFF simulation of free flying aircraft is developed.An accurate Computational Fluid Dynamics/Computational Structural Dynamics/six-degree-of-freedom equation(CFD/CSD/6DOF)-based BFF prediction method is proposed.Firstly,the time-domain CFD/CSD method is used to calculate the static equilibrium state of the model.Based on this state,the CFD/CSD/6DOF equation is solved in time domain to evaluate the structural response of themodel.Then combinedwith the variable stiffnessmethod,the critical flutter point of the model is obtained.This method is applied to the BFF calculation of a flyingwing model.The calculation results of the BFF characteristics of the model agree well with those fromthe modalmethod andNastran software.Finally,the method is used to analyze the influence factors of BFF.The analysis results show that the flutter speed can be improved by either releasing plunge constraint or moving the center ofmass forward or increasing the pitch inertia.

Triad-displaced ULAs configuration for non-circular sources with larger continuous virtual aperture and enhanced degrees of freedom

Non-uniform linear array(NULA)configurations are well renowned due to their structural ability for providing increased degrees of freedom(DOF)and wider array aperture than uniform linear arrays(ULAs).These characteristics play a significant role in improving the direction-of-arrival(DOA)estimation accuracy.However,most of the existing NULA geometries are primarily applicable to circular sources(CSs),while they limitedly improve the DOF and continuous virtual aperture for noncircular sources(NCSs).Toward this purpose,we present a triaddisplaced ULAs(Tdis-ULAs)configuration for NCS.The TdisULAs structure generally consists of three ULAs,which are appropriately placed.The proposed antenna array approach fully exploits the non-circular characteristics of the sources.Given the same number of elements,the Tdis-ULAs design achieves more DOF and larger hole-free co-array aperture than its sparse array competitors.Advantageously,the number of uniform DOF,optimal distribution of elements among the ULAs,and precise element positions are uniquely determined by the closed-form expressions.Moreover,the proposed array also produces a filled resulting co-array.Numerical simulations are conducted to show the performance advantages of the proposed Tdis-ULAs configuration over its counterpart designs.

Degree of Freedom Analysis for Holographic MIMO Based on a Mutual-Coupling-Compliant Channel Model

Degree of freedom(DOF)is a key indicator for spatial multiplexing layers of a wireless channel.Traditionally,the channel of a multiple-input multiple-output(MIMO)half-wavelength dipole array has a DOF that equals the antenna number.However,recent studies suggest that the DOF could be less than the antenna number when strong mutual coupling is considered.We utilize a mutual-coupling-compliant channel model to investigate the DOF of the holographic MIMO(HMIMO)channel and give a upper bound of the DOF with strong mutual coupling.Our numerical simulations demonstrate that a dense array can support more DOF per unit aperture as compared with a half-wavelength MIMO system.

Physical Modeling and Parametric Study on Two-Degree-of-Freedom VIV of A Cylinder near Rigid Wall

Unlike most previous studies on the transverse vortex-induced vibration（VlV） of a cylinder mainly under the wallfree condition （Williamson ＆ Govardhan, 2004）, this paper experimentally investigates the vortex-induced vibration of a cylinder with two degrees of freedom near a rigid wall exposed to steady flow. The amplitude and frequency responses of the cylinder are discussed. The lee wake flow patterns of the cylinder undergoin^g VIV were visualized by employing the hydrogen bubble technique. The effects of the gap-to-diameter ratio （eo/D） and the mass ratio on the vibration amplitude and frequency are analyzed. Comparisons of VIV response of the cylinder are made between one degree （only transverse） and two degrees of freedom （streamwise and transverse） and those between the present study and previous ones. The experimental observation indicates that there are two types of streamwise vibration, i.e. the first streamwise vibration （FSV） with small amplitude and the second streamwise vibration （SSV） which coexists with transverse vibration. The vortex shedding pattern for the FSV is approximately syrmnetric and that for the SSV is ahernate. The first streamwise vibration tends to disappear with the decrease of eo/D. For the case of large gap-to-dianeter ratios （ e.g. eo/D = 0. 54 ～ 1.58）, the maximum amplitudes of the second streamwise vibration and transverse one increase with the increasing gap- to-diameter ratio. But for the case of small gap-to-diameter ratios （e. g. eo/D= 0. 16, 0.23）, the vibration amplitude of the cylinder increases slowly at the initial stage （i.e. at small reduced velocity Vr）, and across the maximum amplitude it decreases quickly at the last stage （i.e. at large Vr）. Within the range of the examined small mass ratio （m 〈 4）, both streamwise and transverse vibration amplitude of the cylinder decrease with the increase of mass ratio for the fixed value of Vr- The vibration range （ in terms of Vr） tends to widen with the decrease of the mass ratio. In the second streamwise vibration region, the vibration frequency of the cylinder with a small mass ratio （ e.g. mx = 1.44） undergoes a jump at a certain Vr＋ The maximum amplitudes of the transverse vibration for two-degree-of-freedom case is larger than that for one-degree-of-freedom case, but the transverse vibration frequency of the cylinder with two degrees of freedom is lower than that with one degree of freedom（transverse）.

Trimming the Degrees of Freedom via a K^(+) Flux Rectifier for Safe and Long‑Life Potassium‑Ion Batteries

High degrees of freedom(DOF)for K^(+)movement in the electrolytes is desirable,because the resulting high ionic conductivity helps improve potassium-ion batteries,yet requiring support from highly free and flammable organic solvent molecules,seriously affecting battery safety.Here,we develop a K^(+)flux rectifier to trim K ion’s DOF to 1 and improve electrochemical properties.Although the ionic conductivity is compromised in the K^(+)flux rectifier,the overall electrochemical performance of PIBs was improved.An oxidation stability improvement from 4.0 to 5.9 V was realized,and the formation of dendrites and the dissolution of organic cathodes were inhibited.Consequently,the K||K cells continuously cycled over 3,700 h;K||Cu cells operated stably over 800 cycles with the Coulombic efficiency exceeding 99%;and K||graphite cells exhibited high-capacity retention over 74.7%after 1,500 cycles.Moreover,the 3,4,9,10-perylenetetracarboxylic diimide organic cathodes operated for more than 2,100 cycles and reached year-scale-cycling time.We fabricated a 2.18 Ah pouch cell with no significant capacity fading observed after 100 cycles.

Temperature Control Based on Fuzzy Logic Two-degree-of-freedom Smith Internal Model

According to the characteristics of the large time delay,nonlinearity and the great inertia of temperature control system in biomass pyrolysis reactor,a two-degree-of-freedom Smith internal model controller based on fuzzy control is proposed.Firstly,the mathematical model of the temperature control system is established by using the step response method,and then the two-degree-of-freedom Smith internal model controller is designed,and the good tracking performance and disturbance suppression performance can be obtained by designing the set value tracking controller and interference rejection capability.Secondly,the fuzzy control algorithm is used to realize the on-line tuning of the control parameters of the two-degree-of-freedom Smith internal model algorithm.The simulation results show that,compared with the traditional internal model control,fuzzy internal model PID control and two-degree-of-freedom Smith internal model control,the algorithm proposed in this paper improves the influence of lag time on the control system,realizes the separation control of set point tracking and anti-jamming performance and the self-tuning of control parameters,and improves the control performance of the system.

Freedom EVO全自动酶联免疫前处理仪故障分析

全自动酶联免疫前处理是一种高自动化酶免诊断分析仪,用于检验科各类样品的液体处理工作。仪器在正常保养的情况下,由于标本量巨大、项目繁多,运行过程中不可避免地会出现故障。以Freedom EVO全自动酶联免疫前处理为例,分析总结使用过程中出现的常见故障及解决方法,以尽快解决故障,提高检验质量和工作效率,确保设备长期有效的运行,供操作及维护人员参考。

The Kinematics Performance of Self-Propelled Full Freedom Filament in Wakes of Flow around Cylinder

In vortex streets, the kinematics performance of self-propelled full freedom filament is closely related to the length and the position of filaments in the flow field. In this paper, the changes of passive propulsion velocity and pressure of full-degree-of-freedom filaments after cylindrical wake were analyzed by 15 sets of experiments when the length and position of filaments were changed. The results show that the propulsive velocity of the filament, it approximately increases first and then decreases with the filament length increasing, and the further away from the center of the cylinder, the smaller the propulsive velocity of the filament. In addition, the longer the filament length and the further it is from the center of the cylinder, the lower the pressure around the filament. Experiments show that filaments without energy input can obtain energy from the surrounding flow field to maintain self-propelled motion. Studying the influence of length and position on the kinematics of filaments is helpful to provide a reference for revealing the hydrodynamic mechanism on passive propulsion process and developing low resistance energy harvesting device in swimming fish movement.

ON THE HOMOCLINIC ORBITS IN A CLASS OF TWO-DEGREE-OF-FREEDOM SYSTEMS UNDER THE RESONANCE CONDITIONS

A class of two-degree-of-freedom systems in resonance with an external, parametric excitation is investigated, the existence of the periodic solutions locked to Omega is proved by the use of the method of multiple scales. This systems can be transformed into the systems of Wiggins under some conditions. A calculating formula which determines the existence of homoclinic orbits of the systems is given.

The Prisoner of“Freedom”:Cultural Displacement of Santosh in Naipaul’s In a Free State

In a Free State is a post-colonial novel written by Naipaul.“One out of Many”is one of the stories in this novel to explore the freedom of the culturally rootless.The protagonist,Santosh,lives under the collision between the Indian culture and American culture.In the“crevice”of two different cultures,he is deeply involved in the tumultuous and painful process of cultural displacement.His behaviors in cultural displacement can be divided into three stages.Firstly,he has experienced a“cultural shock”after his arrival in Washington,D.C.as a new comer.Secondly,after being fully exposed to the host culture and American style,he has experienced assimilation and absorption to be like an American.Finally when he escapes from his employer and chooses his own way of living,he finds that he is not free at all because he is confronted with an awkward cultural dilemma:he can neither return to his past life;nor can he aspire to a better future.The anxiety about the dislocation causes misery for his fate.As a result,he becomes a prisoner in an unfamiliar culture,and his“freedom”can only be a rootless“freedom”.

Set-point Filter Design for a Two-degree-of-freedom Fractional Control System

This paper focuses on a new approach to design(possibly fractional) set-point filters for fractional control systems.After designing a smooth and monotonic desired output signal,the necessary command signal is obtained via fractional input-output inversion.Then,a set-point filter is determined based on the synthesized command signal.The filter is computed by minimizing the 2-norm of the difference between the command signal and the filter step response.The proposed methodology allows the designer to synthesize both integer and fractional setpoint filters.The pros and cons of both solutions are discussed in details.This approach is suitable for the design of two degreeof-freedom controllers capable to make the set-point tracking performance almost independent from the feedback part of the controller.Simulation results show the effectiveness of the proposed methodology.

The Conflict and Balance Between Intellectual Property Rights and Public Freedom of Information in the“Anti-circumvention Clause”

There is a long-standing conflict between intellectual property rights and public freedom of information.The continuous development of the“anti-circumvention clause”has caused the conflict to intensify.As a basic human right,freedom of information is being gradually eroded by the expansion of intellectual property rights.The existing research mainly carries on the right balance from the negative protection path,but the positive protection path is more advantageous to realizing the public freedom of information and alleviates the conflict between the two kinds of rights.In practice,there are some problems in the application of the anti-circumvention clause,such as the legality of the aim,the division of the protected part,and the determination of the circumvention.This is mainly due to the lack of restrictions on technical measures,the failure to distinguish between“copyright protection”and“contact control”,and the offside and absence of administrative bodies in practice.We should protect public freedom of information by distinguishing the two measures of copyright protection and contact control and the two torts of access and use,increasing the restrictive conditions for the use of technical protection measures,and changing the functions of administrative supervision agencies.

公序良俗在情人遗赠纠纷中的适用——基于私法与基本权利冲突理论的二元视角

遗赠是否违背公序良俗应以遗赠本身为审查对象,而不能以遗赠以外之事实为断。同时,情人遗赠行为是否违背公序良俗,尤应考察当事人一方遗赠的动机是否是将性奉献与经济上的对待给付联结起来,抑或是存在其他更值得尊重的动机。但在私法视角下,情人遗赠的效力,总是呈现出完全有效或完全无效的形态。而在基本权利冲突与权衡的视角下,各基本权利相互较量各自在具体个案中的分量,此种权衡和较量之结果体现在法律行为效力上,即既非完全有效亦非完全无效,而是在两者间存在多种可能性,因而更能适应个案中的具体情况,也更具灵活性。

宪法视野下的婚检制度变革与完善——基于《民法典》第1053条告知义务的履行

《民法典》第1053条对禁婚疾病传统作出重大调整,成为新时代背景下婚检制度设计的重要法律依据。在婚姻宪法保护框架下,“婚姻自由—私人告知—自愿婚检”的传统思路忽略了比“婚姻自由保护”更为根本的“婚姻传统功能保护”。婚姻的公共性及解决相关司法实践难题的客观需要,使得婚检融入履行环节成为可能。从《宪法》到《民法典》再到《婚姻登记条例》,民法典时代婚检制度设计应沿循“婚姻保护—法定告知—弱强制婚检”设计思路,采取“程序强制+形式审查”模式,即当事人于婚前相互告知专业健康检查结论,婚姻登记机关仅要求当事人填写知晓声明并进行必要口头提示而不对告知内容及其真实性进行实质审查。

自由的实现:黑格尔与马克思

自由的实现是黑格尔和马克思思想的共同主题,也是二者的分歧所在。在《法哲学原理》中,黑格尔批判了法国大革命“绝对自由”的原则,试图以理性国家统一普遍与特殊,调和个体与共同体之间的矛盾,最终实现私人领域和公共领域的统一。在一个有机共同体中实现具体的自由,这一点成为后来马克思共产主义观念的理论起点,也构成后者的原则高度。不同的是,马克思敏锐地发现了黑格尔理性国家的问题,把对市民社会的批判推进到政治经济学批判中,进而在哲学批判、政治经济学批判以及各种形式的社会主义理论及其现实运动的批判这一总体性的视野中为黑格尔的伦理自由找到了一条通达现实的道路——共产主义及其现实运动。因此,作为观念与现实的统一,马克思的共产主义就在根本上超越了黑格尔的理性国家,是自由的真正实现,即人类解放。

基于改进麻雀优化PID的波浪补偿控制方法

随着海上风电“十四五”规划的不断推动,在深远海域对兆瓦级大功率海上风机的需求量随之增加,其规模也在不断扩大。但是,在吊运、安装等海上工作过程中,复杂海浪对船舶产生的持续影响导致风机安装的精度和效率大幅下降,甚至会对人员安全以及财产造成重大损失。在深远海域复杂海况下对工程船舶进行有效的波浪补偿,可提供稳定的作业环境以保证精准高效地完成各项工作,因此,本文提出了一种基于改进麻雀优化PID的波浪补偿控制方法并将其应用于Stewart补偿平台。首先,建立波浪补偿平台动力学以及运动学反解模型,并设计正解模型迭代求解算法。随后,使用PID进行波浪补偿控制,并通过麻雀搜索算法优化参数。接着,采用Circle混沌映射对其进行初始化分布,以解决初始化不均匀的问题;并采用动态自适应加权、柯西突变以及反向学习以提升算法全局寻优能力。最后,生成4~6级海况下的某工程船运动数据作为系统输入,利用MATLAB和Simulink软件平台搭建模型进行补偿控制验证,并在Stewart硬件平台上做补偿试验。结果表明,改进麻雀搜索算法具有较快的收敛速度、较高的精度和更好的寻优能力,优化后的PID控制方法更适合用于复杂海况下波浪补偿平台的控制优化,可为大功率海上风机安装的补偿平台控制系统设计提供参考。

营商环境法治化三维论

市场秩序稳定公平、规则透明公开、法治公正、投资可预期的营商环境,是投资主体实现投资自由便利制度的核心价值所现。推进政府职能新定位,强化“放管服”,放宽市场主体准入等,是优化营商环境的基本环节。自由度是主体最活跃的动力源和策源地,政府确保“中立地位”,促进主体公平竞争和实施反垄断,维护所有市场主体都享有平等、自由、公平竞争机制。便利度是彰显政府向市场主体提供快速实现自由度的便捷化、快捷化和效率化的社会效应程度,核心在于强化市场主体获得从商活动权利能力的快捷、简便、高效行为状态等。创新度是市场主体实现自由度与便利度融合发展处于动态的追求状态,显现了优化营商环境持续创新的法治动力。政府干预与市场调节有机协同调控,做大主体自由度,提升主体更多便利度,促进营商环境的持续创新优化。自由、便利与创新,已成为优化营商环境的路径选择,创新成为优化营商环境的否定之否定规律。自由度、便利度与创新度的辩证关系价值,成为引导探寻优化营商环境的立足点、突破点和发力点。

基于双自由度转台的全向空间单目视觉室内定位测量方法

针对传统单目视觉测量系统测量视场有限的问题,本文提出一种基于双自由度旋转平台的全向空间单目视觉测量方法。首先,对双自由度旋转平台的转轴参数进行标定,用副相机拍摄固定在双自由度转台上的棋盘格标定板,提取棋盘格角点的位置坐标,并将其转化到同一相机坐标系下。利用PCA(主成分分析)平面拟合得到初始位置转轴参数中的方向向量,使用空间最小二乘圆拟合方法得到初始位置下转轴参数中的位置参数。然后,通过转台转动的角度以及罗德里格斯公式将不同位置下相机获取的数据进行坐标系统一,实现水平和竖直方向全向空间下的目标测量。最后,通过高精度激光测距仪验证了本方法的测量精度,并通过与双目视觉测量系统、wMPS测量系统进行比对实验,验证了本方法的全向空间测量能力。实验结果表明,本方法测量精度基本达到双目视觉测量系统水平,但测量范围远大于双目视觉测量,可以满足全向空间测量要求。

罗马法复兴与近代欧洲的自由主义传统

自由主义是一个近现代的概念,但也有古代渊源。古代罗马的法律观、人性观、政治观中都具有近代自由主义的元素,这些古老的思想通过罗马法的复兴运动重新回到了中世纪,给社会带来了深刻的变革。16—18世纪罗马法复兴的新浪潮更是直接促进了古典自由主义的诞生。17世纪以来,古典自由主义学者基于前述研究成果论述了自由主义的人性观、财产观与法治观,构建了西方的自由主义传统。回顾自由主义的发展历史,可以发现罗马法的复兴既是自由主义连续发展的关键,也给予了自由主义新风格。它不仅是学术上的复古运动,同时也对西方社会变革产生了深远的影响。

针对半月板损伤患者的运动学步态分析

目的:探讨应用Codamotion 2CX1三维动态关节运动捕捉系统分析不同程度半月板损伤患者运动学特征。方法:2020年12月至2022年6月收治的半月板损伤患者及招募的正常人共135例,男82例,女53例;年龄14~29岁;病程1~3个月。结合临床症状及MRI检查明确半月板损伤诊断,根据Stoller分级标准将半月板损伤分为4级:0级(正常)37例,Ⅰ级30例,Ⅱ级33例,Ⅲ级35例。采用Codamotion 2CX1三维动态关节运动捕捉系统对各组受试者进行行走测试,采集步行及运动学定量化指标,包括膝关节屈伸、内外旋、内外翻,并对其进行运动学进行分析。结果:在膝关节屈曲/伸直的分布中,4组患者膝关节最大屈曲、最小伸直及膝关节屈伸范围比较,差异有统计学意义(P<0.05);在膝关节内旋/外旋的分布中,4组患者膝关节内旋及膝关节旋转范围比较,差异有统计学意义(P<0.05);在膝关节内翻/外翻的分布中,4组患者膝关节外翻及膝关节翻转范围比较,差异有统计学意义(P<0.05);临床分期进展与膝关节伸直、外旋、内外翻及翻转活动范围呈正相关(P<0.05);与膝关节屈曲、内旋及屈伸、旋转活动范围呈现负相关(P<0.05);膝关节内旋、外旋角度可以作为半月板损伤临床分期的独立影响因素(P=0.006,0.019<0.05)。结论:半月板损伤患者膝关节运动发生了明显变化,且不同临床分期下,变化有一定差异,步态分析为半月板损伤的运动学分析提供了一个可靠的依据,有助于更好了解关节的运动学指标,同时提供了一个较为可靠的辅助诊疗方案,为后续医学研究提供了新方向。