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.

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.

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.

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.

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.

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”.

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.

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。

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。

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。

基于定位法线的工件最少定位点布局规划方法

以建立满足工序需求的工件定位点数量最少的定位布局为目标,以定位法线为介质,基于定位法线的工件定位的几何定理,推论出工件自由度与定位法线关系,获得自由度约束模型的定位法线信息;建立工件自由度数学模型,运用逻辑减运算法则建立工件各类型自由度之间关系,获得自由度模型的规划方案;根据规划方案中的定位法线信息,得出定位点初始布局。利用典型实例详细介绍了基于定位法线进行工件定位点布局规划的应用过程。该方法仅需自由度信息,规划过程简便,适用于各类工件,尤其是复杂工件的初步定位方案设计。

稳定分析中滑动面构造方法分析

滑动面的构造方法是边坡稳定分析的关键课题之一。任意滑动面的构造比较复杂,基于Logistic函数积分等基函数构造的曲线可以代替传统的折线形滑动面,改善滑动面的光滑性,也有利于减少其自由度。对基于基函数的滑动面构造方法进行梳理,将其划分为基于连续函数叠加的构造方法和基于积分运算的构造方法。重点对Logistic函数及其积分的性质进行分析,得到了不同参数对曲线形态的影响规律,从而缩小了相关参数的取值范围,为减小滑动面自由度提供了依据。在此基础上也给出了一种确定给定滑动面参数初值的方法。针对两个边坡算例的计算表明,所提出的方法能够满足边坡稳定分析的要求。

“自由的解放”:论马克思主义对主体实践“元信念”的重估

主体实践的“元信念”具有作为主体实践的起点和动力的“元原因”和作为主体实践的终极标准的“元尺度”两重意蕴。然而无论是功利主义还是德国古典哲学的义务论对这两重意蕴的解释都因其理论体系的封闭性和自足性而无法与主体实践进行彻底的结合。马克思通过将社会历史的视角重新引入对主体实践“元信念”的解释中,通过对“自由”和“实践”的同一化理解,指出主体实践的“元信念”正是能动的实践在具体社会历史中不断展开的倾向。因其受到了阶级社会的深重阻碍,故必须通过无产阶级革命与阶级社会彻底决裂,在“全部可能性展开”的共产主义社会中通过对实践活动作为“第一需要”的认识才能实现主体实践“元信念”两重意蕴的真正统一以及其自身的彻底完成。

半无限介质多自由度频响函数离散时间有理近似的稳定参数识别

离散时间有理近似函数是将半无限土频响函数转化为时域模型的重要工具,离散时间有理近似函数和时域模型具有相同的稳定性和精度。目前关于离散时间有理近似函数的研究只针对于单自由度系统。该文基于线性控制理论,给出了多自由度有理近似系统的稳定条件。将稳定性条件与遗传-序列二次算法相结合,开发了多自由度频响函数参数辨识方法,保证了多自由度系统的稳定性和精度。不同维度的多自由度有理近似系统的数值仿真验证了该文方法可以保证多自由度有理近似系统的稳定性和精度。

美国教师表达自由的法律标准及实践

美国在规制教师表达自由时有比普通公民更严格的法律标准。其实质标准要求教师在私人生活中模范遵守公序良俗,在教育实践中遵守履职专业规范;形式标准主要有分类规制原则、价值中立原则和公共论坛原理。在规制教师表达时,美国司法审查围绕“教育”形成了教育本位、利益衡平、路径清晰等特点。这些做法对我国完善规制教师表达自由的法规政策有一定参考价值。

高校学术权力的异化表征与归正路径

学术权力既是高校办学自主权的重要内容,也是大学组织的基础权力。然而,当前我国高校学术权力的异化现象较为严重,这种异化的负向力量会降低公众对于学术权力的心理预期,进而影响高校治学管理和学术研究顺利运行。高校学术权力异化主要表现在高校学术权力主体异化、高校学术权力活动异化、高校学术权力配置异化及高校学术权力监督异化等方面,高校学术主体道德失范、政府过多干预高校学术管理、高校学术权力行政化色彩和高校学术权力法律地位缺乏独立是造成高校学术权力异化的主要归因。回归高校学术权力的本真要义,应进一步规范高校学术权力主体行为、明确高校学术权力运行规则、协调高校“学术”与“行政”权力关系及健全高校学术权力监督机制。

自由的两种面相——再论艾丽丝·门罗的《逃离》

艾丽丝·门罗的中篇小说《逃离》历来被置于女性主义理论的阐释窠臼,评论者通常赞许女主人公卡拉的逃离,而对她的回归却颇有微词,认为这是对男权妥协的无奈之举。这种模式的解读忽视了小说更为丰富的细节和意象。要理解卡拉的逃离与回归,首先需要厘清自由不同层次的内涵。在西方文化中,自由除了指人身自由,还指在世的精神自由,卡拉的两次逃离是对无所束缚的人身自由的追寻,回归则意味着她将自由保留在精神的范畴,而担负起自己在世的责任。小说中小羊弗洛拉这一文化意象,一方面呼应着卡拉的命运,另一方面其拯救功能也昭示了卡拉回归的意义。

下腰椎椎体在不同负荷下屈伸运动特点的分析

目的探索不同负重状态下直立位腰椎L_(3)、L_(4)椎体屈伸运动过程中体运动轨迹,分析负重状态下腰椎在体运动的规律和特点。方法招募2018年8月至2020年8月10名无症状的青年志愿者,使用双荧光透视系统DFIS与CT相匹配技术,经平扫CT获取L_(3)~S_(1)的图像进行三维重建。于放射线透视不同负重下0、5、10 kg完成下腰椎的前屈到直立到后伸动作获得X线影像,通过轮廓重叠实现二维到三维图像的匹配,还原下腰椎椎体的三维运动轨迹。结果下腰椎在前屈到站立位时:不同负重下腰椎椎体0、5、10 kg的X轴的运动位移分别为-1.05(-2.42,1.72)、0.63(0.15,4.26)、-0.39(-0.75,3.12)mm。X轴运动位移比较5 kg>10 kg>0 kg,差异有统计学意义(P<0.05)。γ角度分别为-0.26(-1.30,5.43)、0.93(0.24,5.42)、-0.95(-2.12,4.32)°。γ角度比较5 kg>0 kg>10 kg,差异有统计学意义(P<0.05)。下腰椎在站立到后伸位时:不同负重下腰椎椎体0、5、10 kg X轴的运动位移分别为0.90(-0.82,3.74)、-0.91(-1.55,4.26)、0.07(-0.92,3.25)mm。Z轴的运动位移分别为-0.25(-0.54,1.78)、0.40(-0.68,2.37)、-0.19(-0.92,1.03)mm。X轴运动位移比较0 kg>10 kg>5 kg,Z轴运动位移比较5 kg>10 kg>0 kg,差异有统计学意义(P<0.05)。α角度分别为0.91(-0.82,2.85)、-0.61(-0.14,3.79)、0.54(-0.82,3.87)°。γ角度分别为1.15(0.24,5.32)、0.92(-0.67,5.45)、0.65(-1.24,5.32)°。α角度比较0 kg>10 kg>5 kg,γ角度比较0 kg>5 kg>10 kg,差异有统计学意义(P<0.05)。结论负重5 kg下腰椎椎体在体运动的位移和旋转角度和0 kg相比差异有统计学意义,可能与腰椎退行性疾病有一定关联。下腰椎退行性疾病可能与X轴位移的关系更为密切。

六自由度运动模拟平台设计与分析

针对实际道路测试周期长、成本高、容易受到恶劣天气影响等问题,设计一种能够用于车载光电跟踪系统进行模拟试验的六自由度摇摆台。模拟扰动测试,通过六自由度摇摆台提供扰动;对六自由度摇摆台进行结构设计、运动及频率特性分析。结果表明,该摇摆台能够推导其固有频率与机构刚度矩阵和质量矩阵的关系。