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1.
Tokay geckos are skillful climbers and are able to negotiate difficult terrain such as steep slopes and overhanging inclines without losing their foothold. Here, we present data on the changes in locomotor kinematics when geckos are challenged to walk on various inclined surfaces. We trained individual geckos to move along a platform which can be tilted to simulate different slopes. The animals were filmed using a high-speed video camera. The results showed that their speed decreased with increasing slope angle, and their speed on the steep and inverted slopes (sloped angle 〉60~) decreased at a faster rate than on the shallow slopes (sloped angle 〈60~). The geckos' stride length was much greater on the shallow slopes compared to the inverted slopes. The influence of stride length and stride frequency on speed was different when the geckos moved across different slopes. There are significant differences duty factor, which varied from 0.54 when wall climbing (90° slope) to 0.84 when walking on the ceiling (180° slope). The mechanisms revealed this study will improve our understanding of control strategies in kinematics and inspire the design of robots with greater mobility.  相似文献   

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3.
蛤蚧发声通路核团定位的初步研究   总被引:2,自引:0,他引:2  
采用辣根过氧化物酶(HRP)方法和电刺激技术对爬行类动物蛤蚧发声通路的神经核团进行了定位研究。结果表明:在延脑部位,疑核和迷走神经运动核参与对蛤蚧发声活动的调节,但以疑核对发声活动的调节作用最为重要。疑核对蛤蚧发声器的支配为双侧性的,但以同侧为主。而迷走神经运动核只有单侧的标记。实验结果提示,中脑的中央灰质区(SGC)的背外侧核团可能通过对凝核的调节来影响蛤蚧的发声活动,大脑皮质的背侧皮质区(DX)也可能参与对发声活动的调节,且均为双侧性的调节作用。  相似文献   

4.
为了研究盾构掘进过程对周边桩基础内力的影响,结合苏州轻轨1号线玉山公园与苏州乐园盾构隧道区间的施工情况,采用三维有限元数值模型,研究盾构施工过程对单桩内力的动态影响.结果表明:在盾构施工过程中,侧桩的轴力均呈现桩顶和桩底处小、隧道轴线处最大的特点,侧桩的轴力和弯矩随盾构的不断逼近而变大,且最大负弯矩大于最大正弯矩;同时侧桩越长,桩身轴力也越大,不同长度侧桩的弯矩均在隧道轴线处最大.在盾构从正下方穿越单桩的施工过程中,桩身轴力均呈现中间小、两端大的特点,最大弯矩均出现在桩身中点附近.当盾构切削面到达正上方单桩时,桩变长后,桩身部分截面的轴力由压力变为拉力,桩身弯矩均在桩中点附近处达到最大值.  相似文献   

5.
Geckos are known for their excellent ability to climb walls and run on ceilings. Previous studies of the gecko’s locomotive and adhesive mechanisms, its neuro-sensory and neuro-modulatory systems, its fabrication of artificial setae array, and other related developments, have inspired further research on gecko-based and gecko-like robots. Key research findings in this area are reviewed in the present paper.  相似文献   

6.
Geckos are known for their excellent ability to climb walls and run on ceilings. Previous studies of the gecko's locomotive and adhesive mechanisms, its neuro-sensory and neuro-modulatory systems, its fabrication of artificial setae array, and other related developments, have inspired further research on gecko-based and gecko-like robots. Key research findings in this area are reviewed in the present paper.  相似文献   

7.
To study the modulation mechanism of the middle brain of the Gekko to the locomotion, we introduced a stereotaxic method first in literature and developed an apparatus suitable for Gekko gecko, the big-gest wall and ceiling climber in nature. We defined the bregma and nasal points as reference points, selected the bilateral infraorbital margin and top point of the maxillary tooth for locating and fixing, and set up the line passing through the bregma and paralleling to a line connecting the bilateral infraorbital margin as x axis. Then, we defined a horizontal plane in the stereotaxic instrument, passing through x axis and the certain point which is 4.8 mm exactly above the nasal point, as the XOY plane; the sagittal plane, i.e. the YOZ plane, is the plane which is perpendicular to x axis and passes through the bregma; the plane, i.e. the XOZ plane, which passes through x axis and is perpendicular to the horizontal plane is the coronal plane. We designed a set of head holder which includes three parts: bilateral infraorbital margin clamps, a gecko adaptor holding the rostral side of the upper jaw. The allocation and operation of the head holder is accurate and simple, and the device is low in cost and compatible with standard stereotaxic instrument.  相似文献   

8.
用原子力显微镜(atomic force microscopy,AFM)对凝胶法生长的KClO4晶体的最重要面{001}面微观形貌进行了研究。结果表明,在不同的过饱和度下,KClO4晶体分别表现为二维成核生长、三维成核生长、层核生长以及多层堆垛生长等生长机理。从热力学角度解释了过饱和度对KClO4晶体生长机理的影响。对二维成核生长机理,揭示了KClO4晶体生长中二维核的形状和取向,及生长台阶的取向。研究结果还表明,杂质的存在将阻止台阶的向前推进,并导致聚并台阶及弯曲台阶的形成。  相似文献   

9.
通过体内外黏附实验优选复方丹参黏附微丸黏附材料,并对微丸体外释放度进行考察.利用挤出滚圆法制备普通微丸、HPMC微丸、壳聚糖微丸、壳聚糖/HPMC混合微丸.以在体肠黏附实验评价微丸黏附性能,结果显示壳聚糖/HPMC混合微丸具有更高的黏附指数.通过转篮法测定微丸体外释放度,结果显示丹酚酸B、三七皂苷类成分及丹参酮ⅡA于12h内持续释放,其中丹酚酸B于12h内释放接近80%;三七皂苷R_1、人参皂苷Rg_1于12h内均释放完全.人参皂苷Rb112h内释放达84.23%,人参皂苷Rd达81.93%.丹参酮ⅡA释放缓慢,12h内持续释放,达48.02%,成功实现在体黏附和缓释.  相似文献   

10.
采用种子乳液聚合法,以丙烯酸丁酯、甲基丙烯酸甲酯等为单体,加入乳化剂、引发剂、链转移剂合成了液体可剥离胶。考察了单体配比、乳化剂、聚合温度、聚合反应时间等因素对聚合的影响。  相似文献   

11.
采用种子乳液聚合法,以丙烯酸丁酯、甲基丙烯酸甲酯等为单体,加入乳化剂、引发剂、链转移剂合成了液体可剥离胶。考察了单体配比、乳化剂、聚合温度、聚合反应时间等因素对聚合的影响。  相似文献   

12.
He  LingHui  Ding  KeWei 《科学通报(英文版)》2009,54(11):1970-1972
Exemplified by adhesive contact of a rigid sphere with equiaxially stretched elastomeric substrates, the effect of finite pre-strain on adhesion behavior is studied based on the JKR model. The analysis indi- cates that the pre-strain reduces the contact area between the sphere and the substrate, but does not alter the adhesion strength.  相似文献   

13.
为研究频率法在单索玻璃幕墙拉索索力监测中的准确性,基于某单索玻璃幕墙索力监测项目,采用有限元软件ANSYS建立幕墙拉索在不同边界条件下的振动模型,分析模拟频率与实测频率之间的关系,结果表明:幕墙拉索的边界条件更接近两端固支,并且短索更明显;高阶频率(n=3~6)较低阶频率(n=1~2)更稳定。将幕墙拉索的实测频率与边界条件为两端固支的模拟频率(n=3~6)进行比对,得到弦理论公式的频率修正系数为0.968,提出索力修正计算公式,其适用于长细比在270~340之间的单索玻璃幕墙拉索。采用弓式测力计法对修正公式进行验证,索力相对误差为-5.4%,表明该修正公式能有效提高索力计算精度。  相似文献   

14.
The advent of atomic force microscopy (AFM) provides a powerful tool for investigating the behaviors of single living cells under near physiological conditions. Besides acquiring the images of cellular ultra-microstruc- tures with nanometer resolution, the most remarkable advances are achieved on the use of AFM indenting tech- nique to quantify the mechanical properties of single living ceils. By indenting single living cells with AFM tip, we can obtain the mechanical properties of cells and monitor their dynamic changes during the biological processes (e.g., after the stimulation of drugs). AFM indentation-based mechan- ical analysis of single cells provides a novel approach to characterize the behaviors of cells from the perspective of biomechanics, considerably complementing the traditional biological experimental methods. Now, AFM indentation technique has been widely used in the life sciences, yielding a large amount of novel information that is meaningful to our understanding of the underlying mechanisms that govern the cellular biological functions. Here, based on the authors' own researches on AFM measurement of cellular mechani- cal properties, the principle and method of AFM indentationtechnique was presented, the recent progress of measuring the cellular mechanical properties using AFM was summa- rized, and the challenges of AFM single-cell nanomechani- cal analysis were discussed.  相似文献   

15.
本文报导了一种新型氧化淀粉粘合剂合成方法.其特点是:a)冷制,节约能源.b)设备工艺简短.c)成本低,不足800元/T.d)粘度大,用途广.e)稳定性好.  相似文献   

16.
Blinov BB  Moehring DL  Duan L  Monroe C 《Nature》2004,428(6979):153-157
An outstanding goal in quantum information science is the faithful mapping of quantum information between a stable quantum memory and a reliable quantum communication channel. This would allow, for example, quantum communication over remote distances, quantum teleportation of matter and distributed quantum computing over a 'quantum internet'. Because quantum states cannot in general be copied, quantum information can only be distributed in these and other applications by entangling the quantum memory with the communication channel. Here we report quantum entanglement between an ideal quantum memory--represented by a single trapped 111Cd+ ion--and an ideal quantum communication channel, provided by a single photon that is emitted spontaneously from the ion. Appropriate coincidence measurements between the quantum states of the photon polarization and the trapped ion memory are used to verify their entanglement directly. Our direct observation of entanglement between stationary and 'flying' qubits is accomplished without using cavity quantum electrodynamic techniques or prepared non-classical light sources. We envision that this source of entanglement may be used for a variety of quantum communication protocols and for seeding large-scale entangled states of trapped ion qubits for scalable quantum computing.  相似文献   

17.
In nature, geckos have developed complex adhesion structures capable of smart adhesion, which is the ability to cling to different smooth and rough surfaces, even ceilings, and detach at will. The hierarchical structure of gecko foot hairs consists of microscale setae, branches and nanoscale spatulae, which contributes to their strong adhesion on different surfaces. In this paper, we propose a simple and low-cost method for fabricating two-level high aspect ratio microfiber arrays that mimic gecko foot hairs. SU-8 photoresist was used and single-level SU-8 microfiber arrays were obtained by a thick film photolithography process. Single-level polydimethyl-siloxane (PDMS) microfiber arrays were also obtained by a micromolding process and the master template for this process was fabricated using inductively coupled plasma (ICP) technology. Using the silicon mold with deep-hole arrays as a substrate, an SU-8 layer with microhole arrays was added to it using thick film photolithography and it formed a double stack mold from which the two-level hierarchical PDMS microfiber arrays were replicated. Water contact angle tests showed that the two-level hierarchical structures are extremely hydrophobic (about 148.5° compared with the Tokay gecko’s 160°).  相似文献   

18.
Poly(allylamine hydrochloride) (PAH), which is frequently used in fabricating polyelectrolyte multilayer films, was studied by single molecule force spectroscopy (SMFS). Plenty of force-extension curves with a long plateau were obtained in water, indicating that train-like structure was predominant when PAH was adsorbed on the substrate. It was found that the peak-type force-extension curves of PAH in water were not able to be fitted by the modified freely-jointed chain model. Additionally, there was a flat region in the derivative of force-extension curves. Thus, it was inferred that PAH chain in water was in a special conformation and underwent a "conformational transition" under the stretching of an external force. This phenomenon did not appear in the SMFS experiment in 1 mol/L urea solution, which indicated that urea was able to break the special conformation.  相似文献   

19.
以MMA为硬单体,EA、BA为软单体,NMA和AA为交联单体,OP和SDS为乳化剂,过硫酸铵为引发剂合成可低温固化的聚丙烯酸酯胶黏剂.探讨了各单体配比,乳化剂、引发剂用量及温度条件对转化率的影响.使用该胶黏剂植绒时,100℃下固化7 min,所得植绒产品柔软度佳,各项指标均达到FZ/T64011—2001《静电植绒织物》标准.  相似文献   

20.
以聚乙烯醇(PVA)和甲醛为主要原料,制备了聚乙烯醇缩甲醛(PVF)胶粘剂。研究了PVA与甲醛溶液的质量比(MpvA/M甲醛)、缩合反应时间、缩合温度及pH对产品性能的影响,获得了制备PVF胶粘剂的最佳工艺条件。在此条件下,通过加入改性剂,在提高粘结强度和耐水性的同时,降低了游离甲醛含量,制得了环保且性能优良的PVF胶粘剂。  相似文献   

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