科创中国

首先对物流配送及相关理论进行了综述,提出了共同配送模式在广西-东盟物流中的应用,同时,对广西现行的自营配送模式与共同配送模式进行了比较,并从成本、路线、经营主体等方面进行了定性、定量分析,由此,得出了自营配送模式存在成本高、路线不完善、经济主体单一等一系列问题,而共同配送模式更适合于广西物流发展的现状,并提出了共同配送的三种组织模式在广西物流应用中的优势和劣势.最后,提出了共同配送模式在广西物流配送应用中需要注意的问题及其对策.

Most of current running quadruped robots have similar construction: a stiff body and four compliant legs. Many researches have indicated that the stiff body without spine motion is a main factor in limitation of robots' mobility. Therefore, investigating spine motion is very important to build robots with better mobility. A planar quadruped robot is designed based on cheetahs' morphology. There is a spinal driving joint in the body of the robot. When the spinal driving joint acts, the robot has spine motion; otherwise, the robot has not spine motion. Six group prototype experiments with the robot are carried out to study the effect of spine motion on mobility. In each group, there are two comparative experiments: the spinal driving joint acts in one experiment but does not in the other experiment. The results of the prototype experiments indicate that the average speeds of the robot with spine motion are 8.7%–15.9% larger than those of the robot without spine motion. Furthermore, a simplified sagittal plane model of quadruped mammals is introduced. The simplified model also has a spinal driving joint. Using a similar process as the prototype experiments, six group simulation experiments with the simplified model are conducted. The results of the simulation experiments show that the maximum rear leg horizontal thrusts of the simplified mode with spine motion are 68.2%–71.3% larger than those of the simplified mode without spine motion. Hence, it is found that spine motion can increase the average running speed and the intrinsic reason of speed increase is the improvement of the maximum rear leg horizontal thrust.

Straight-line compliant mechanisms are important building blocks to design a linear-motion stage,which is very useful in precision applications.However,only a few configurations of straight-line compliant mechanisms are applicable.To construct more kinds of them,an approach to design large-displacement straight-line flexural mechanisms with rotational flexural joints is proposed,which is based on a viewpoint that the straight-line motion is regarded as a compromise of rigid and compliant parasitic motion of a rotational flexural joint.An analytical design method based on the Taylor series expansion is proposed to quickly obtain an approximate solution.To illustrate and verify the proposed method,two kinds of flexural joints,cross-axis hinge and leaf-type isosceles-trapezoidal flexural(LITF)pivot are used to reconstruct straight-line flexural mechanisms.Their performances are obtained by analytic and FEA method respectively.The comparisons of the results show the accuracy of the approach.Both examples show that the proposed approach can convert a large-deflection flexural joint into approximate straight-line mechanism with a high linearity that is higher than 5 000within 5 mm displacement.This can lead to a new way to design,analyze or optimize straight-line flexure mechanisms.

"行不行"在现代汉语中可表疑问、征询、祈使、感叹、反驳等语气,这些句法功能的不同,与其句法分布由句内一句外一固化的演变有关,"行不行"已不仅仅是一个疑问标记,还是一个多功能标记."行不行"的发展过程,也是一个"主观化"过程,由命题成分变为话语成分,由客观意义变为主观意义等,随着语法化程度的不断加深,"行不行"的疑问功能渐渐削弱,逐渐固化为祈使、感叹和话语标记."行不行"能用于正反问句,与"行"表"可以"情态义的出现紧密相关,伴随着"行不行"的语法化,"行不行"的固化也有词汇化的因素.

以某拱坝为例,深入分析了不同固结灌浆阶段拱坝出现裂缝的成因和机理.高温季节控制固结灌浆上抬压力是避免开裂的关键;低温季节固结灌浆时表面温度应力是主导因素,尤其是出现长间歇期时.结合反馈分析与预报仿真结果,提出高温季节固结灌浆时应合理控制盖重厚度、灌浆压力以及灌浆开始的龄期;低温季节固结灌浆时,要做好保温工作.此外还可考虑采用无盖重灌浆来减小长间歇时间.

Several typical flexible pneumatic actuators(FPA) and different mechanical models describing their behaviors have been proposed, however, it is difficult to balance compliance and load capacity in conventional designs, and these models still have limitations in predicting behavior of FPAs. A new flexible pneumatic bending joint(FPBJ) with special anisotropic rigidity structure is proposed. The FPBJ is developed as an improvement with regard to existing types of FPA, and its principal characteristic is derived from the special anisotropic rigidity structure. With this structure, the load capacity in the direction perpendicular to bending plane is strengthened. The structure of the new FPBJ is explained and a mathematical model is derived based on Euler-Bernoulli beam model and Hook's law. To obtain optimum design and usage, some key structure parameters and input-output characteristics are simulated. The simulation results reveal that the relationship between the structure parameters and FPBJ's bending angle is nonlinear. At last, according to the simulation results, the FPBJ is manufactured with optional parameters and tested. The experimental results show that the joint's statics characteristics are reflected by the mathematical model accurately when the FPBJ is deflated. The maximum relative error between simulation and experimental results is less than 6%. However, the model still has limitations. When the joint is inflated, the maximum relative error reaches 20%. This paper proposes a new flexible pneumatic bending joint which has sufficient load capacity and compliance, and the mathematical model provides theoretical guidance for the FPBJ's structure design.

安氏Ⅱ类错胎是正畸临床中常见的错胎畸形,促进颞下颌关节(TMJ)和下颌骨的生长改建是正畸治疗追求的目标.许多学者针对逐步和一次最大程度前移下颌对矫治效果及TMJ改建的影响进行了大量的临床及实验研究.本文就此作一综述.