Partitioning the energetics of walking and running: swinging the limbs is expensive

Explaining the energetics of walking and running has been difficult because the distribution of energy use among individual muscles has not been known. We estimated energy use by measuring blood flow to the hindlimb muscles in guinea fowl. Blood flow to skeletal muscles is controlled locally and varies directly with metabolic rate. We estimate that the swing-phase muscles consume 26% of the energy used by the limbs and the stance-phase muscles consume the remaining 74%, independent of speed. Thus, contrary to some previous suggestions, swinging the limbs requires an appreciable fraction of the energy used during terrestrial legged locomotion. Models integrating the energetics and mechanics of running will benefit from more detailed information on the distribution of energy use by the muscles.     

动态检测与容错机器人

提出了机器人容错模型,设计了多智能体机器人的框架结构,并且对各部分功能进行了详细说明。为了提供具备检测和隔离能力的接口,提出了使用有效数据进行检测的方法。最后采用故障树对机器人的可靠性进行了分析。     

一类Lienard系统的中心—焦点问题

为了定性地研究微分方程系统，通常要讨论中心－焦点问题。本文讨论了一类Ｌｉｅｎａｒｄ系统，通过证明定理，指出连续奇，偶次这类系统在原点具有不同的拓扑结构（即相连奇，偶次系统不能同时为中心），以便于进一步求得该系统的焦点量上界问题。     

不定方程x^2-py^2=z^2的正整数解

研究了一类不定方程求正整数解的问题.借助一个引理,推导并证明了不定方程x^2-py^2=z^2（p为奇素数）正整数解的一般公式.不定方程x^2-py^2=z^2（p为奇素数）满足（x,y）=1的一切正整数解可表示为x=12（a^2＋pb^2）,y=ab,z=│12a2-pb2│,这里a〉0,b〉0,a,b都是奇数,p a;或x=a^2＋pb^2,y=2ab,z=│a2-pb2│,这里a〉0,b〉0,a,b一奇一偶,p a.     

Broken-symmetry states in doubly gated suspended bilayer graphene

The single-particle energy spectra of graphene and its bilayer counterpart exhibit multiple degeneracies that arise through inherent symmetries. Interactions among charge carriers should spontaneously break these symmetries and lead to ordered states that exhibit energy gaps. In the quantum Hall regime, these states are predicted to be ferromagnetic in nature, whereby the system becomes spin polarized, layer polarized, or both. The parabolic dispersion of bilayer graphene makes it susceptible to interaction-induced symmetry breaking even at zero magnetic field. We investigated the underlying order of the various broken-symmetry states in bilayer graphene suspended between top and bottom gate electrodes. We deduced the order parameter of the various quantum Hall ferromagnetic states by controllably breaking the spin and sublattice symmetries. At small carrier density, we identified three distinct broken-symmetry states, one of which is consistent with either spontaneously broken time-reversal symmetry or spontaneously broken rotational symmetry.     

高阶色散对光纤耦合器不稳定性影响的计数机模拟

从光纤耦合器的耦合模方程出发,用奇偶超模对其进行重写,讨论了当输入条件使奇次超模被单独激发时,计算机数值模拟了高阶色散对光纤耦合器稳定性的影响,结果表明:光纤耦合器中在正常和反常色散区均存在不稳定性,并且不稳定性与3阶色散项无关、与4阶色散项有关,给出了增益谱在不同色散区随输入功率的变化关系.     

Scattering and interference in epitaxial graphene

A single sheet of carbon, graphene, exhibits unexpected electronic properties that arise from quantum state symmetries, which restrict the scattering of its charge carriers. Understanding the role of defects in the transport properties of graphene is central to realizing future electronics based on carbon. Scanning tunneling spectroscopy was used to measure quasiparticle interference patterns in epitaxial graphene grown on SiC(0001). Energy-resolved maps of the local density of states reveal modulations on two different length scales, reflecting both intravalley and intervalley scattering. Although such scattering in graphene can be suppressed because of the symmetries of the Dirac quasiparticles, we show that, when its source is atomic-scale lattice defects, wave functions of different symmetries can mix.     

正整数分拆成公差为偶数的等差分拆

讨论了将正整数n分拆成连续奇数或者连续偶数的分拆,给出了这类分拆数与正整数n的满足一定条件的因数个数之间的关系,并将这些结论作了推广,得到了正整数n分拆成公差为偶数的等差分拆数的结果.     

How animals move: an integrative view

Recent advances in integrative studies of locomotion have revealed several general principles. Energy storage and exchange mechanisms discovered in walking and running bipeds apply to multilegged locomotion and even to flying and swimming. Nonpropulsive lateral forces can be sizable, but they may benefit stability, maneuverability, or other criteria that become apparent in natural environments. Locomotor control systems combine rapid mechanical preflexes with multimodal sensory feedback and feedforward commands. Muscles have a surprising variety of functions in locomotion, serving as motors, brakes, springs, and struts. Integrative approaches reveal not only how each component within a locomotor system operates but how they function as a collective whole.     

基于模型的仿射约化割线法的收敛性

本文讨论了精确线性搜索下,基于模型的仿射约化判战法的全局收效性。     

A tunable kondo effect in quantum dots

A tunable Kondo effect has been realized in small quantum dots. A dot can be switched from a Kondo system to a non-Kondo system as the number of electrons on the dot is changed from odd to even. The Kondo temperature can be tuned by means of a gate voltage as a single-particle energy state nears the Fermi energy. Measurements of the temperature and magnetic field dependence of a Coulomb-blockaded dot show good agreement with predictions of both equilibrium and nonequilibrium Kondo effects.     

两年一代落叶松毛虫的生物学特性

研究了２年一代落叶松毛虫Ｄｅｎｄｒｏｌｉｍｕｓ Ｓｕｐｅｒａｎｓ（Ｂｕｔｌｅｒ）的生物学特性。完成一个世代跨３个年度７３０ｄ左右，下一世代约有１０％进入１年一代虫，１年一代虫的下一世代均进入２年一代虫。２年一代虫在第２年的小署及大署期间进行越夏。大虫、大虫在奇数、偶数年间交替发生。     

Euglena gracilis: a novel lipid energy reserve and arachidonic acid enrichment during fasting

In Euglena gracilis grown in the dark, was esters, consisting of a combination of medium-chain fatty acids and alcohols that contain both odd and even numbers of carbon atoms, appear to be a reservoir for metabolic energy. When the organisms are fasted, their pellicular membrane systems become quite rich in long-chain polyenoic acids, mostly of the arachidonic acid family.     

German farmers’ intention to use autonomous field robots: a PLS-analysis

Autonomous field robots are a promising technology for solving several problems in agriculture, as they are electrical driven, can control weeds single-plant based mechanically or with microdoses of pesticides and exert less ground pressure on the field. Whether such robots will be applied on a large scale in German agriculture depends on various parameters. Therefore, the factors influencing the behavioural intention of farmers with respect to their future adoption of autonomous field robots were investigated. The analysis applies a structural equation model based on an extended version of the Unified Theory of Acceptance and Use of Technology. The dataset, collected in 2019, consists of 500 German farmers. The results reveal significantly positive effects of farmers’ expected performance, social influence and trust as well as significantly negative effects of farmers’ effort expectancy and anxiety on the behavioural intention to use autonomous field robots. Additionally, moderating effects of age on the relationship of individual constructs to the behavioural intent to use robots could be confirmed. The results provide important information for various stakeholders. Robot suppliers should better inform farmers about the performance of their products, for instance by involving farmers in the development process of the robots. The ecological benefits attributed to field robots could meet public expectations and should be better communicated to address farmers’ social influence on the behavioural intention to use the robots. Policymakers could try to create better framework conditions, for example by establishing a stable legal situation for autonomous systems or promote its use.

     

计算机图形学中二维布尔运算的稳定性分析

系统介绍了二维图形布尔运算的原理及其计算机实现，详细分析了被覆盖实体的起点在覆盖多边形边界上时布尔运算的不稳定性，给出了当被覆盖实体起点在覆盖多边形边界上时奇偶段的取舍规则，应用该规则可提高算法的稳定性。     

图K4,4∨Kt 的点可区别正常边染色

讨论了图K4,4∨Kt的点可区别正常边染色及其色数.利用正多边形的对称性构造染色以及组合分析的方法.确定了图K4,4∨Kt的点可区别正常边色数,得到了:当t是奇数且t≥3以及t是偶数且2≤t≤32时,χ′s(K4,4∨Kt)=t+8;当t是偶数且t≥34时,χ′s(K4,4∨Kt)=t+9.     

非完整性约束移动机器人的鲁棒控制研究

分析了移动机器人中的轮式机器人在非完整约束条件下的建模问题,并以三轮小车式移动机器人为例讨论了运动学模型建模。应用鲁棒控制技术,设计了移动机器人轨迹跟踪控制方法,并仿真实现。     

Behavioral neurophysiology: insights into seeing and grasping

One marvels at a batter's ability to hit a baseball traveling at 150 kilometers per hour or a monkey's skill in snatching a flying insect. Indeed, the ability of many animals to reach out, grasp, and manipulate objects is a feat of biological engineering unmatched by even state-of-the-art robots. But how are the objects of our attention chosen and how are the eyes and hands directed to it? Recent progress in behavioral neurophysiology has clarified some of the brain mechanisms at work.     

Biomechanics. Geckos climb by the hairs of their toes

Biomechanists have uncovered the secret of how the gecko manages to run up walls and across ceilings: rows of tiny hairs with multiple split ends on the bottom of each toe pad. As they report in the 8 June issue of Nature, weak attractive forces between the 1000 or so split ends on each hair and the ceiling help the gecko grab even the smoothest surface. Armed with that knowledge, the researchers hope to design synthetic "footpads" to improve the maneuverability of robots and perhaps to design an entirely new type of adhesive.     

小型人力水稻收割机的改进设计

改进设计后的割禾器主机，基本解决了原割禾器存在的刀片磨损集中、寿命低的问题。由于动刀片每个齿都参与切割，所以，磨损较均匀。设计使动、定刀片皆可自磨锐，切割功率随时问增加反而有所下降。刀片磨损后，只要调整动定刀间隙即可继续切割，刀片寿命估计比原来的要提高4倍以上。由于推进只是起到行走和预切割部分茎秆的作用，切割主要还是由动刀旋转来完成。