摘要：Tissue engineering is an emerging means for resolving the problems of tissue repair and organ replacement in regenerative *** supply of nutrients and oxygen to cells in large-scale tissues has led to the demand to prepare blood ***-based tissue engineering approaches are effective methods to form new blood vessel *** demand for blood vessels prompts systematic research on fabrication strategies of vascular scaffolds for tissue *** advances in 3D printing have facilitated fabrication of vascular scaffolds,contributing to broad prospects for tissue *** review presents state of the art on modeling methods,print materials and preparation processes for fabrication of vascular scaffolds,and discusses the advantages and application fields of each ***,significance and importance of scaffold-based tissue engineering for vascular regeneration are *** materials and preparation processes are discussed in *** a focus is placed on preparation processes based on 3D printing technologies and traditional manufacturing technologies including casting,electrospinning,and Lego-like *** related studies are *** of vascular scaffolds to clinical application is ***,four trends of 3D printing of tissue engineering vascular scaffolds are presented,including machine learning,near-infrared photopolymerization,4D printing,and combination of self-assembly and 3D printing-based methods.

摘要：Multi-wall carbon nanotube filled shape memory polymer composite(MWCNT/SMC)possessed enhanced modulus,strength,and electric conductivity,as well as excellent electrothermal shape memory properties,showing wide design scenarios and engineering application *** thermoelectrically triggered shape memory process contains complex multi-physical mechanisms,especially when coupled with finite deformation rooted on micro-mechanisms.A multi-physical finite deformation model is necessary to get a deep understanding on the coupled electro-thermomechanical properties of electrothermal shape memory composites(ESMCs),beneficial to its design and wide *** into consideration of micro-physical mechanisms of the MWCNTs interacting with double-chain networks,a finite deformation theoretical model is developed in this work based on two superimposed network chains of physically crosslinked network formed among MWCNTs and the chemically crosslinked *** intact crosslinked chemical network is considered featuring with entropic-hyperelastic properties,superimposed with a physically crosslinked network where percolation theory is based on electric conductivity and electric-heating *** model is calibrated by experiments and used for shape recoveries triggered by heating and electric *** captures the coupled electro-thermomechanical behavior of ESMCs and provides design guidelines for MWCNTs filled shape memory polymers.

摘要：Near net-shape production of complex parts with higher mechanical properties is one of the most important final goals of the recent researches on the semi-solid *** the knowledge of the influence of every parameter on the properties of final parts is the key in the production of high quality complex *** these parameters forming temperature and velocity,and reheating and holding times have the greatest effects on the final mechanical properties of the *** influence of the parameters of non-dendritic billet production,forming speed,temperature and holding time on the properties of semi-solid extruded parts were ***-slope method was employed in order to produce non-dendritic *** material used was A356 aluminum *** the number of the parameters influencing the final properties of the parts was high(these parameters include:cooling slope angle,ram velocity,temperature and holding time),the final number of the experiments required would be n4,in which n is the number of the states of the parameters(5 in our case).In order to reduce this amount,design of experiments Tachuchi method was employed(design L25).Using this method the number of required experiments was reduced to *** the experiments the prepared semi-solid samples were extruded under isothermal condition and with 5 different ram *** tensile tests were conducted on the extruded parts and the mechanical properties of the parts were *** obtained results analyzed with MiniTab and the influence of each of the parameters and also the percentage of its influence were *** an optimum region for the parameters was *** temperature,ram speed,slope angle and holding time have more important effects descendingly.

摘要：The selected modifications to the construction of grinding wheels were described which facilitate an increase in the material removal rate （grinding wheels with conic chamfer and grinding wheels with microdiscontinuities on the active surface）. Using these background details, a suggested thesis was put forward regarding the need to develop a device which will allow for the shaping of the macrogeometry of the grinding wheel （cylindrical and conical surfaces） and the microdiscontinuities within the dressing operation simultaneously. The device was presented and prepared in two functional variants （horizontal and vertical mounting of the motor）, then a prototype was described. An example of the grinding wheel active surface, shaped by using this device, was also presented. The theoretical analysis and experimental verification performed determine that the error of shaping the conic chamfer angle within the range of 0-1.5°, using the developed device, is approximately ±3%.

摘要：Thermophotovoltaic （TPV） system has been regarded as one promising means to alleviate current energy demand because it can directly generate electricity from radiation heat via photons. However, the presently available TPV systems suffer from low conversion efficiency and low throughput. A viable solution to increase their efficiency is to apply micro/nanoscale radiation principles in the design of different components to utilize the characteristics ~f thermal radiation at small distances and in microstructures. Several critical issues are reviewed, such as photovoltaic effect, quantum efficiency and efficiency of TPV system. Emphasis is given to the development of wavelength-selective emitters and filters and the aspects of micro/nanoscale heat transfer. Recent progress, along with the challenges and opportunities for future development of TPV systems are also outlined.

摘要：Flexible risers are crucial pieces of equipment for moving output fluids from wells to platforms during the extraction of oil and gas from deepsea *** of the causes of collapse in these pipes is the high hydrostatic pressure applied to risers in deep *** innermost layer of a riser,known as the carcass layer,plays a critical role in resistance to external *** this study,we investigated the collapse(nonlinear buckling)of a riser under external pressure,and a novel design based on the structure of a beetle’s exoskeleton was used to increase the load capacity of the carcass *** type of beetle skeleton is constructed in such a way that it creates strong connections among the various parts of the external skeleton to considerably enhance strength against external pressure while allowing necessary *** assess the performance of the design in comparison with the original design,we examined the nonlinear buckling of the new structure under external *** genetic algorithm optimization,design parameters were obtained,and the maximum strength before collapse was *** show that the critical pressure in the new design substantially increases relative to that in the original design.

摘要：Synthesizing the mechanical models of the belt, the driver and the take-up device, the dynamics model was established on the longitudinal vibration of the overall belt conveyor system with finite elemental method, and S-function simulation block of asynchronous motor owing feedback function was built in Matlab/Simulink software, the simulation block indicates that motor rotation speed and its output moment vary with load and time, and the motor is a dynamic feedback system in working process. The state space block was adopted to express model of the belt. Thus it created simulation model of established dynamic model of overall belt conveyor system with Mat- lab/Simulink software, and simulates the course of starting by properly setting simulation parameters, and processes data for visualization.

摘要：Ceramic is an important material with outstanding physical properties whereas impurities and porosities generated by traditional manufacturing methods limits its further industrial applications. In order to solve this problem, direct fabrication of Al2O3 ceramic structures is conducted by laser engineered net shaping system and pure ceramic powders. Grain refinement strengthening method by doping Zr O2 and dispersion strengthening method by doping Si C are proposed to suppress cracks in fabricating Al2O3 structure. Phase compositions, microstructures as well as mechanical properties of fabricated specimens are then analyzed. The results show that the proposed two methods are effective in suppressing cracks and structures of single-bead wall, arc and cylinder ring are successfully deposited. Stable phase of α-Al2O3 and t-Zr O2 are obtained in the fabricated specimens. Micro-hardness higher than 1700 HV are also achieved for both Al2O3 and Al2O3/Zr O2, which are resulted from fine directional crystals generated by the melting-solidification process. Results presented indicate that additive manufacturing is a very attractive technique for the production of high-performance ceramic structures in a single step.

摘要：Product innovation can be achieved by analyzing leading products patents in the *** methods have been proposed for design around patent,commonly using the elimination or replacement of a single patent element However,the existing research fails to restore the position and function of the design around object in the original patent portfolio of enterprises,which often leads to the phenomenon of evading one patent and violating *** paper proposes a method for design around patent through using the fusion of technologies of the evolution theory and bundle-type patent portfolio analysis in the initial stage of product *** object system is analyzed to select technical opportunities through the evolutionary path of technologies and functional trimming methods to achieve circumvent barriers of bundle-type *** bundle patent portfolio is analyzed for the product evolution with a radar *** technological evolution path is combined with the TRIZ innovation method to identify and solve the design *** of the new design is evaluated using the patent system rules for innovative scheme difference from the original patent *** method is verified in a case study for the design of a glass-wiping *** design solution has been patented.

摘要：Elastic diodes with nonreciprocity have the potential to enable unidirectional modulation of elastic ***,it is a challenge to achieve nonreciprocity at low frequencies(<100 Hz)using existing elastic *** paper proposes a quasizero-stiffness(QZS)elastic diode to resolve such a tough issue and fulfill high-quality low-frequency *** proposed elastic diode is invented by combining a QZS locally resonant metamaterial with a linear one,where the beneficial nonlinearity of the QZS metamaterial facilitates opening an amplitude-dependent band gap at very low ***,the dispersion relation of the QZS metamaterial is derived theoretically based on the harmonic balance method(HBM).Then,the transmissibility of the QZS elastic diode in both the forward and backward directions is calculated through theoretical analyses and numerical ***,the influences of system parameters on the low-frequency nonreciprocal effect are *** results indicate that considerable nonreciprocity is observed at a quite low frequency(e.g.,9 Hz),which is achieved by amplitude-dependent local resonance combined with interface ***,a machine learning-based design optimization is introduced to evaluate and enhance the nonreciprocal effect of the QZS elastic *** the aid of machine learning(ML),the computational cost of predicting nonreciprocal effects during design optimization can be significantly *** design optimization,the nonreciprocal frequency bandwidth can be broadened while maintaining considerable isolation quality at low frequencies.