aaaselect * from OA left join Issue on OA.Issue_No=Issue.Issue_No left join Iuuse_Year on Issue.Issue_Year=Iuuse_Year.Issue_Year where OA.Issue_No='2018年4期' order by Page_Num 纳米技术与精密工程 /nm/oa Review of low timing jitter mode-locked fiber lasers and applications in dual-comb absolute distance measurement /nm/oa/darticle.aspx?type=view&id=2018401 &nbsp;Passively mode-locked fiber lasers emit femtosecond pulse trains with excellent short-term stability. The quantum-limited timing jitter of a free running femtosecond erbium-doped fiber laser working at room temperature is considerably below one femtosecond at high Fourier frequency. The ultrashort pulse train with ultralow timing jitter enables absolute time-of-flight measurements based on a dual-comb implementation, which is typically composed of a pair of optical frequency combs generated by femtosecond lasers. Dead-zone-free absolute distance measurement with sub-micrometer precision and kHz update rate has been routinely achieved with a dual-comb configuration, which is promising for a number of precision manufacturing applications, from large step-structure measurements prevalent in microelectronic profilometry to three coordinate measurements in large-scale aerospace manufacturing and shipbuilding. In this paper, we first review the sub-femtosecond preci?sion timing jitter characterization methods and approaches for ultralow timing jitter mode-locked fiber laser design. Then, we provide an overview of the state-of-the-art dual-comb absolute ranging technology in terms of working principles, experimental implementations, and measurement precisions. Finally, we discuss the impact of quantum-limited timing jitter on the dual-comb ranging precision at a high update rate. The route to high?precision dual-comb range finder design based on ultralow jitter femtosecond fiber lasers is proposed. 2018年12月15 00:00 2018年4期 205 217 3968895 &nbsp;Haosen Shi 1, Youjian Song 1, Runmin Li, Yuepeng Li, Hui Cao, Haochen Tian, Bowen Liu, Lu Chai, Minglie Hu Investigation on tool wear and tool life prediction in micro-milling of Ti-6Al-4V /nm/oa/darticle.aspx?type=view&id=2018402 &nbsp;Short tool life and rapid tool wear in micromachining of hard-to-machine materials remain a barrier to the process being economically viable. In this study, standard procedures and conditions set by the ISO for tool life testing in milling were used to analyze the wear of tungsten carbide micro-end-milling tools through<br />slot milling conducted on titanium alloy Ti-6Al-4V. Tool wear was characterized by flank wear rate, cutting-edge radius change, and tool volumetric change. The effect of machining parameters, such as cut?ting speed and feedrate, on tool wear was investigated with reference to surface roughness and geometric<br />accuracy of the finished workpiece. Experimental data indicate different modes of tool wear throughout machining, where nonuniform flank wear and abrasive wear are the dominant wear modes. High cutting speed and low feedrate can reduce the tool wear rate and improve the tool life during micromachining.<br />However, the low feedrate enhances the plowing effect on the cutting zone, resulting in reduced surface quality and leading to burr formation and premature tool failure. This study concludes with a proposal of tool rejection criteria for micro-milling of Ti-6Al-4V. 2018年12月15 00:00 2018年4期 218 225 1804336 &nbsp;Amin Dadgari a, Dehong Huo a, David Swailes b &nbsp;CFD-based design and analysis of air-bearing-supported paint spray spindle /nm/oa/darticle.aspx?type=view&id=2018403 In this paper, an analytical scientific approach is presented for the design and analysis of an air-turbine-driven paint spray spindle, and it is used to improve further the design concept of the existing spindle applied in auto?motive coating and paint spraying applications. The current spindle on the market can operate at a maximum speed of 100,000 rpm and features a maximum bell size of 70 mm diameter. Given the increasing demands for high automotive coating/painting quality and productivity in assembly, the design and development of a paint spray spindle with a speed of 145,000 rpm or higher is needed. Computational fluid dynamics (CFD)-based simulation is applied in the approach. Accordingly, CFD simulation-based design and analysis are undertaken, covering the characteristic factors of velocity, pressure of the air supply, rotational speed of the air-turbine, and torque and force reaction on the turbine blades. Furthermore, the turbine blade geometric shape is investigated through the simulations. Three geometrical concepts have been investigated against the original model. The results on<br />Concept_03 verified the higher angular velocity speeds against the theoretical model. The pressure and velocity effects in the blades have been investigated. The results show that the pressure and velocity of the air supply driving the turbine are critical factors influencing the stability of turbine spinning. The results also demonstrate that the force acting on the blades is at the highest level when the adjacent face changes from a straight surface into a curve. Finally, changing the geometrical shape in the turbine likely increases the tangential air pressure at the blades surface and relatively increases the magnitude of the lateral torque and force in the spindle. Notwithstand?ing this condition, the analytical values surpass the theoretical target values. 2018年12月15 00:00 2018年4期 226 235 4418835 &nbsp;Ali Khaghani , Kai Cheng Effect of particle-particle interaction on dielectrophoretic single particle trap in a sudden contraction flow /nm/oa/darticle.aspx?type=view&id=2018404 Dielectrophoretic (DEP) force is significant in manipulating tiny objects in micro/nano scale. To study the effect of electric interaction force on particle manipulation, a microstructure consisting of a pair of strip electrodes and a sudden contraction micro-channel was constructed. Besides DEP force and hydrodynamic force acting on single particle, the numerical model also involved electric interaction force and force moment on two particles. The analyses revealed that the particle-particle interaction force was in the same order as that of DEP force on single trapped particle. The interaction force resulted in trapping single particle failure under continuous DEP force. Thus, pulsed DEP force, turning on/off DEP force at a given time interval, was suggested. During the “off” period, the velocity difference of the two particles located at sudden contraction micro-channel enlarged the gap be?tween them and further weakened the particle-particle interaction. By a proof-of-concept experiment, both the trapping behavior of single particle and that of two particles were in good agreement with the model. With carefully controlled parameters, the reliable function of retaining single particle was realized by pulsed DEP. 2018年12月15 00:00 2018年4期 236 241 870797 &nbsp;Haihang Cui , Rui Ma, Li Chen, Hongyan Zhang &nbsp;Finite element simulation of the micromachining of nanosized-silicon-carbide-particle reinforced composite materials based on the cohesive zone model /nm/oa/darticle.aspx?type=view&id=2018405 &nbsp;A finite element method based on the cohesive zone model was used to study the micromachining process of nanosized silicon-carbide-particle (SiCp) reinforced aluminum matrix composites. As a hierarchical multiscale simulation method, the parameters for the cohesive zone model were obtained from the stress-displacement curves of the molecular dynamics simulation. The model considers the random properties of the silicon-carbide-particle distribution and the interface of bonding between the silicon carbide particles and the matrix. The machining mechanics was analyzed according to the chip morphology, stress distribution, cutting temperature, and cutting force. The simulation results revealed that the random distribution of nanosized SiCp causes non-uniform interaction between the tool and the reinforcement particles. This deformation mechanics leads to inhomogeneous stress distribution and irregular cutting force variation. 2018年12月15 00:00 2018年4期 242 247 2364918 &nbsp;Hongmin Pen a,, Jianhua Guo b, Zizhen Cao a, Xianchong Wang a, Zhiguo Wang c Study on the method of precision adjustment of star sensor /nm/oa/darticle.aspx?type=view&id=2018406 &nbsp;Star sensors are indispensable spatial measurement sensors for high-resolution earth observation and astronomical observations, and the demand for high measurement accuracy of satellite sensors continues to increase; thus, the star sensor optical machine adjustment error cannot be ignored. The<br />commonly used installation error correction method cannot solely meet the precision analysis require?ments. In this paper, the relationship between the optical machine installation and the star sensor mea?surement error is analyzed, and several common adjustment error correction methods are compared. An<br />adjustment method for optical machines is proposed to meet the requirements of very high precision star sensors. The assembly precision requirements of the investigated very high precision star sensor are analyzed considering the whole machine, and then the optical components are controlled through<br />optical precision adjustments to satisfy the precision requirements. Finally, through the complete ma?chine calibration, the star sensor precision adjustment for an optical machine structure is verified. This method meets the requirements of very high precision sensors and is suitable for the precision adjust?ment of optical machine structures, which is of practical significance to improve the precision of star sensors. 2018年12月15 00:00 2018年4期 248 257 2840792 &nbsp;Xiaoyan Wang, Ran Zheng, Yanpeng Wu, Jianbo Sun, Jun Zhong, Long Wang, Miaomiao Wang