摘要：The optimization design of the parameters, such as the groove depth, groove number, ratio of the groove width to the land width, and spiral angle of a new kind of double spiral grooves face seal, which works under the condition of high velocity, high sealing pressure and ultra-low temperature, is presented under the assump-tion of fixed closure force by finite element analysis method. The results show that the stiffness of the maximum film can be obtained when the ratio of the groove width to the land width is 0.5 and the spiral angle is about 75 degrees, when the influence of the groove number on the sealing performance is not obvious.

摘要：To diminish the thermal load, two ways, that is, in-band direct pumping and micro-rod crystal, could be adopted at the same time. The efficiency of LD in-band direct-pumping side surface polished micro-rod Nd：YVO_4 laser is numerically analyzed. By optimizing parameters such as crystal length, laser mode radius, pump beam radius, doping concentration and crystal cross-section size, the overall efficiency can reach over 50%. It is found that with micro-rod crystal implemented in the laser oscillator, high overall efficiency LD in-band direct-pumping Nd：YVO_4 laser could be realized. High efficiency combined with low thermal load makes this laser an outstanding scheme for building high-power Nd：YVO_4 lasers.

摘要：A novel evaluation term and a more reasonable criterion,which is described by a new parameter of brightness factor for active large mode area fiber design,are *** brightness factor evaluation method is based on the transverse mode competition mechanism in fiber lasers and *** brightness factor can be seen as a description of fiber general property since it can represent the output laser brightness of the fiber laser system and because of its ability to resist the nonlinear effect.A core-doped active large pitch fiber with a core diameter of 190 μm and a mode-field diameter of180 μm is designed by this method,and the designed fiber allows effective single-mode operation.

摘要：The radial force is a critical factor to determine the sealing performance of radial lip *** effects of radial force produced by garter spring and interference on the static contact properties and sealing performance of a radial lip seal are investigated by numerical simulations and ***-element analysis and mixed elastohydrodynamic lubrication simulation are *** force,contact width,temperature in the sealing zone,the reverse pumping rate and friction torque are measured.A critical value of interference for a cost-effectively designed radial lip seal is *** force is required to compensate the decrease of the radial force because of the interference and used as a possible way to obtain intelligent control of sealing *** quantitative results gotten in this study could provide guide for the seal design and improvement.

摘要：For about three decades, DNA-based nanotechnology has been undergoing development as an assembly method for nanostructured materials. The DNA origami method pioneered by Rothemund paved the way for the formation of 3D structures using DNA self assembly. The origami approach uses a long scaffold strand as the input for the self assembly of a few hundred staple strands into desired shapes. Herein, we present a 3D origami "roller" (75 nm in length) designed using caDNAno software. This has the potential to be used as a template to assemble nanoparticles into different pre-defined shapes. The "roller" was characterized with agarose gel electrophoresis, atomic force microscopy (AFM) and transmission electron microscopy (TEM).

摘要：Optimum design of rider-bicycle mechanisms is very important for customizing bicycles and plays a crucial role in the improvement of athletes' performances and in protection of the *** the birth of the first bicycle,people have been keeping optimizing bicycles with respect to physical conditions of *** modern design,the basic structure of a bicycle has been formulized,while many geographic parameters remain *** this paper,the bicycle and the human body are considered as a kinematic mechanism,called rider-bicycle *** optimum design is implemented from the perspective of ***-saving and comfortableness are considered at the same *** corresponding performance charts are drawn and the relationship between the performances and parameters of seat height,crank length and body parameters are *** using these charts,the optimal design method of bicycle's parameters for a specified person is then *** solutions to get suitable seat height and crank length for a person are obtained *** research is of significance for customizing bicycles and design of bicycle robot.

摘要：A five-axis serial-parallel kinematic milling machine, the SPKM 165, is introduced. This machine consists of a three-degree of-freedom parallel module and a two-degree-of-freedom serial table. The SPKM 165 is capable of five-face machining. A discussion of the inverse kinematics of the five-axis control is provided. A dimensional synthesis procedure is presented in terms of motion/force transmissibility. Finite-element analysis was used to evaluate the stiffness of a CAD model before the machine was manufactured. Kinematic calibration was implemented to improve the accuracy of the end effector. The results of a calibration experiment are presented. The stiffness of the developed machine was then measured. Milling experiments were conducted, and the test piece showed that the developed machine has satisfactory performance.

摘要：The conflict detection and resolution in collaborative design is a key issue to maintain multi disciplinary design consistency. This paper proposes a new method for conflict detection and resolution based on constraint satisfaction technique. The representation of design constraint, the interval arithmetic of the constraint satisfaction problem CSP and the conflict resolution strategy based on constraint relaxation and adjustment are introduced. A constraint satisfaction based conflict detection and resolution tool CSCDR is then developed. It can help collaborative designers to detect and resolve the conflicts in time in the early stage of the design process so that the unnecessary design iteration and repeated negotiation are avoided and the design efficiency is then much improved. A design case illustrates the effectiveness of CSCDR.