不同上楼速度下的垂直地面反力

上楼垂直地面反力决定着人体质心在垂直方向上的运动,与垂直方向上的平均行走速度、初速有密切的联系。该文建立了上楼行走垂直方向模型,提出了连续周期行走约束,给出了垂直地面反力表达式,研究了其最大值的影响因素,建立了垂直方向初速与垂直地面反力参数、水平方向平均速度之间的数学关系,并对不同上楼速度下的垂直地面反力最大值变化情况进行了预测。用光学运动捕捉系统和六维力台进行了不同速度下的上楼行走测试,测试结果表明:预测结论较准确,上楼低速行走时更加接近水平行走,为使垂直地面反力最大值变化较小,随着行走速度的增加,垂直方向初速增加。     

融合高度数据的行走定位算法研究

为了提高航姿参考系统跟踪人体行走位移的能力,抑制垂直方向位移的严重漂移,在系统中加入高度计芯片BMP180,并提出了基于互补滤波的信息融合算法,用于提高定位精度.分析发现:漂移是加速度二次积分过程中误差累计造成的,时间越长,精度越差;与之相对,高度计的测量结果几乎没有漂移,但短时精度很低;互补滤波融合了两者的优势,取长补短,提高了垂直方向位移的估计精度.新增加的芯片BMP180价格低廉,互补滤波算法计算量小,实验结果表明垂直方向位移的漂移已经完全消除.     

一种新的变步长LMS算法及在自适应波束形成中的应用

LMS算法是自适应波束形成的经典算法之一,由于其步长中参数是固定值,造成收敛速度与稳态误差之间相互制约,影响算法的性能.因此,提出了基于Sigmoid函数的变步长LMS方法,并且误差e(n)在接近为零时有缓慢变化的特点,分析了α、β与e(n)的函数关系以及对收敛性能的影响.计算机仿真表明,该算法有较好的收敛性能.     

基于异构多源传感的行人长航时变步长误差修正技术

低成本微机电系统(micro-electro-mechanical system,MEMS)传感器广泛应用于行人定位导航中,但在长航时下,MEMS传感器零位会随时间产生漂移,导致行人变步长误差成为主要误差.且传统的足绑式导航利用MEMS传感器自身信息判断零速时刻会出现错判漏判等问题.针对这两点,根据行人步态变化规律,在判断零速时刻时,加入压力传感器辅助的异构多源传感,同时针对系统误差设计了用于补偿的误差修正算法.对比传统方法,该设计可以明显提高导航定位精度,定位精度可提高一个数量级.     

一种新型变步长LMS自适应滤波算法及性能分析

针对现有LMS算法不能同时提高收敛速度及降低稳态误差的矛盾。提出一种在步长参数u(n)与误差e(n)之间建立了一种分段线性函数关系。该关系具有在误差e(n)接近零处缓慢变化的优点,克服了一些变步长LMS算法在自适应稳态阶段u(n)取值偏大的缺陷。实验证明,本算法具有计算量小,抗干扰能力强,性能可以明显改善等优点。     

超宽带矢量测距与惯性传感组合的精准步长计算算法

为适应复杂环境下变步长精准测量要求,提出一种基于超宽带（ultra wide band,UWB）矢量测距和惯性传感组合的精准步长计算算法;针对基于惯性传感组合的步长测算精度受佩戴方式和系统运行时间影响以致无法实现行人步长精准测量和长航时精度保持的问题,提出一种结合足间模型与零速检测联合步长算法。根据行人行走时足部轨迹模型构造足间步长模型,得到准确的步长计算公式;根据足部惯性传感器运动特征进行零速检测并触发UWB测距,结合陀螺解算角度和足间模型公式计算得到步长。实验表明,提出的步长估计算法精度可达98.20%,与传统步长算法相比,误差显著降低。     

多体系统动力学方程的反馈参数自适应约束违约稳定法

约束违约稳定法的反馈参数的正确选择,是影响其计算准确性和稳定性的重要因素之一.通过计算误差、位移约束违约程度和速度约束违约程度3项指标来综合选择反馈参数,提出了一种多体系统动力学方程的反馈参数自适应的约束违约稳定法.数值分析表明：该方法适用于定步长和变步长、显式和隐式算法,有利于减小数值误差的积累和数值解的漂移,执行简单、高效、易于嵌入已有算法,且无需依赖于特定的积分方法.     

基于微机电系统的室内行人航向修正算法

室内环境下的行人导航问题是当前导航领域的研究难点与热点。足绑式微机电系统(MEMS)是行人导航的主要形式之一。针对目前行人导航航向发散的问题,同时避免磁力计引入外部误差,在零速更新(ZUPT)的基础上,研究了磁角速率更新(MARU)的航向修正算法。假定行人处于零速区间时磁场是恒定的,当惯性传感器转动时,磁力计的三维矢量也会相应变化。利用磁场的变化信息作为零速时刻陀螺仪输出角速率的观测值;并通过扩展卡尔曼滤波(EKF)对角速度误差进行补偿,从而限制航向角的漂移。实验结果表明,该算法航向跟踪性强,对航向修正有一定的有效性,其终点定位误差占总路径的0.55%,达到了良好的定位精度。     

一种新型稳定可结合三维本构的近场动力学方法

[目的]针对目前两种近场动力学(PD)理论,键型PD(BPD)无法应用三维材料本构模型,而态型PD在均匀化过程中出现零能模式常导致强非线性问题不稳定的挑战,研究一种新型混合PD(HPD),以增强PD理论在求解复杂强非线性问题时的稳定性和实用性.[方法] HPD方法结合BPD和SPD的优点参照BPD,将PD点与影响域内其他PD物质点相连形成键,键上的力通过键中点截面上的应力及其法向向量的乘积计算得到,应力可由三维本构关系计算,而应变则使用与SPD类似的方法拟合得到.在HPD中,键力方向与键的方向并不一致.最后通过两个数值算例验证了HPD方法的正确性和稳定性.[结果]在第一个算例中,可以观察到两种影响域半径的HPD和有限元方法(FEM)的结果高度相似.力加载行(M-M)中的最大相对误差仅为4.58%,模型顶行(N-N)中的最大相对误差仅为0.51%.相比之下,由于零能模式的存在,SPD的最大相对误差为382.68%和5.61%.在第二个算例中,选择A点作为代表点,比较了3种方法计算的位移时程.在靠近底座的A点,SPD在位移计算的初始阶段表现出较高的精度.然而,当模型进入强非线性时,误差便会...     

双足机器人变步长步行模式的在线生成方法

双足机器人在进行变步长步行模式行走的过程中,步长的突然改变会导致其行走不稳定.为此提出一种双足机器人步长实时变化的步行模式补偿方法.此方法中运用了时间补偿和零力矩点补偿.通过两者的补偿能够使步行模式的步长在发生变化时,在线修正双足机器人实际状态与目标状态的偏差,以保证其行走的稳定性.双足机器人AFU10的步行实验证明了该方法的有效性.     

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

Features of Women's language

Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women＇s language from these perspectives： pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women＇s language, more attention should be paid to language use in social context. What＇s more, the linguistic phenomena in a speaking community can be understood more thoroughly.     

An Analysis of Catherine＇s Character——Wuthering Heights

Wuthering Heights, Emily Bronte＇s only novel, was published in December of 1847 under the pseudonym Ellis Bell. The book did not gain immediate success, but it is now thought one of the finest novels in the English language. Catherine is the key character of this masterpiece, because everybody and everything center on her though she had a short life. We can understand this masterpiece better if we know Catherine well.     

Lower Paleozoic oil relationships within Williston Basin, Canada

The Williston Basin is a significant petroleum province, containing oil production zones that include the Middle Cambrian to Lower Ordovician, Upper Ordovician, Middle Devonian, Upper Devonian and Mississippian and within the Jurassic and Cretaceous. The oils of the Williston Basin exhibit a wide range of geochemical characteristics defined as "oil families", although the geochemical signature of the Cambrian Deadwood Formation and Lower Ordovician Winnipeg reservoired oils does not match any "oil family". Despite their close stratigraphic proximity, it is evident that the oils of the Lower Palaeozoic within the Williston Basin are distinct. This suggests the presence of a new "oil family" within the Williston Basin. Diagnostic geochemical signatures occur in the gasoline range chromatograms, within saturate fraction gas chromatograms and biomarker fingerprints. However, some of the established criteria and cross-plots that are currently used to segregate oils into distinct genetic families within the basin do not always meet with success, particularly when applied to the Lower Palaeozoic oils of the Deadwood and Winnipeg Formation.     

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

On Tragic Consciousness In The Works By Ernest Hemingway

As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.     

Design and analysis of generic LBS application developing platform

Location based services is promising due to its novel working style and contents.A software platform is proposed to provide application programs of typical location based services and support new applications developing efficiently. The analysis shows that this scheme is easy implemented, low cost and adapt to all kinds of mobile nework system.     

橡胶颗粒沥青混合料低温抗裂性试验研究

以AC-13级配为基础,将橡胶颗粒代替部分集料掺入混合料中,以低温弯曲试验为评价方法对不同橡胶颗粒掺量下沥青混合料的低温抗裂性进行研究,并引入应变能密度值对混合料的低温抗裂性进行综合评价.试验结果表明:橡胶颗粒沥青混合料试件的破坏微应变均超过2 300,满足冬寒区的技术指标;无论是否掺加橡胶颗粒,随着温度的下降,沥青混合料破坏时的最大弯拉强度增大,弯拉应变降低,劲度模量增大;弯曲应变能密度在胶粒掺量为1%左右时具有较大的弯曲应变能密度值,此时橡胶颗粒沥青混合料具有较好的低温抗裂性.     

Achieving Unusual States of Matter Under High Pressure

正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-     

Exchange-Correlation and Electronic Excitation Energies from Pairing Matrix Fluctuations

We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-