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High-speed Permanent Magnet Linear Synchronous Motor (PMLSM) is desired by high performance electromagnetic propulsion system. A novel frequency modulation (FM) secondary proposed here to overcome the issues resulting from a big pole pitch of high-speed PMLSM, as well as avoid a damage to the thrust characteristics. Firstly, the topology structure of FM secondary is designed, modeling of the main magnetic field excited by permanent magnets (PMs) is accomplished. And the impacts of FM secondary on the main magnetic field and PM eddy-current loss are presented based on the analytical method and finite element method (FEM). The electromagnetic thrust of PMLSM with FM secondary is calculated, and the influences of FM secondary on thrust characteristics are studied by FEM simulations. Finally, a prototype of PMLSM with FM secondary is manufactured, the experiments are provided to validate the analytical results and simulation results of FM secondary.

High speed linear motor with low thrust ripple is one of the research focuses of high performance systems. This paper proposes a novel secondary topology for Permanent Magnet Linear Synchronous Motor (PMLSM) with high speed, to suppress the thrust ripple. Permanent magnet (PM) width modulation secondary adopts several PMs to excite the main magnetic field per pole. The issues from a big pole pitch which is generally used by high-speed PMLSM, are solved. These PMs have various longitudinal lengths based on the pulse width modulation principle, to achieve a magnetic field with excellent sinusoidal features. First, the topology structure of PM width modulation secondary is designed. The analytical model of the main magnetic field excited by PMs in this novel secondary is established, the electromagnetic thrust is calculated. Furthermore, the influences of PM width modulation secondary on the main magnetic field and thrust properties are analyzed. The comparisons between two PMLSMs employing PM width modulation secondary and Halbach secondary respectively, are provided. Finally, prototypes are manufactured and tested, to verify the effectiveness of the topology proposed in this research.

Optoelectronic packaging is an important component of optical communication systems. However, it is a challenge for the packaging equipment to simultaneously have multiple degrees of freedom (DOF), wide range, and high precision. In this article, a six-degree-of-freedom (6-DOF) compliant parallel platform with all these features is presented. This platform has a parallel basic structure with large-stroke flexible joints. Based on elastokinematic analysis, the inverse kinematics solution of the platform is derived, and the effectiveness of the platform is proved by analyzing the 6-DOF motion via finite element analysis. The reachable workspace of the platform is analyzed, and its solution process is simplified using the inverse distance weighted method. Furthermore, a prototype of the proposed platform is presented and its accuracy is evaluated through experiments. Error compensation is used to significantly improve the motion accuracy of the platform. A closed-loop control that uses optical power meters instead of a multi-DOF detection device is proposed for optoelectronic packaging. The performance of the prototype applied to the packaging of coaxial optoelectronic devices is also demonstrated by experiments. The results demonstrate that the 6-DOF compliant parallel platform can successfully carry out the optical alignment of optoelectronic devices.

In order to solve the problem of high measurement cost and complex operation of position-independent geometric errors (PIGEs) calibration on a five-axis motion platform, this paper first proposes a low-cost pose measurement method, based on monocular vision, which can accurately determine the pose in the environment, even with image shadow and noise. Next, an improved method, combining pose measurement and kinematic parameters identification, is proposed to calibrate a five-axis motion platform. The kinematic error model of the platform and the pose planning of automatic image acquisition are established, providing the pose data and motor position data, required for calibration. Combined with the kinematic loop method, the kinematic parameters of the five-axis motion platform are identified, while the geometric structure parameters are accurately calibrated. Before and after calibration, a circular trajectory of the target coordinate system (TCS) origin, relative to the camera coordinate system (CCS), is used to test the comprehensive accuracy evolution of the five-axis motion platform, by comparing the position and orientation errors of the theoretical circle trajectory to the actual one. The experimental data show that, before and after calibration, the average position error of the five-axis motion platform is reduced by 79.46%, while the average direction error is reduced by 86.53%. The experimental results clearly demonstrate that the proposed calibration method significantly improves the comprehensive motion accuracy of the five-axis motion platform, and they verify the practical value and effectiveness of the calibration scheme.

This paper investigated the thermal stress distribution in laser welding of Ti6Al4V and 2024-T4 alloys using the coupled thermal–mechanical model based on the thermo-elastoplastic theory. The microstructure and hardness of the dissimilar joint were analyzed based on the simulated results. The asymmetry of temperature and stress distribution indicated that the great difference of material properties had significant effects on the uniformity of thermal stress distribution. The combination of experiment and simulation demonstrated that the growth of grains in heat-affected zone and fusion zone was closely related to the thermal cycle process. The good agreement between the simulated and experimental results verified the rationality of the combined heat source model of double ellipsoid and rotating Gaussian body. The coupled model and simulated results could offer the instructive information in laser welding for other dissimilar alloys.

Infrared antireflection of a zinc sulfide (ZnS) surface is important to improve performance of infrared detector systems. In this paper, double-pulse femtosecond laser micro-machining is proposed to fabricate a subwavelength quasi-periodic array (SQA) on ZnS substrate for infrared antireflection. The SQA consisting of approximately 30 million holes within a 2 × 2 cm2 area is uniformly formed in a short time. The double-pulse beam can effectively suppress the surface plasma shielding effect, resulting in obtaining a larger array depth. Further, the SQA depth is tunable by changing pulse energy and pulse delay, and can be used to readily regulate the infrared transmittance spectra as well as hydrophobicity. Additionally, the optical field intensity distributions of the SQA simulated by the rigorous coupled-wave analysis method indicate the modulation effect by the array depth. Finally, the infrared imaging quality captured through an infrared window embedded SQA is evaluated by a self-built infrared detection system.

In this study, a highly reliable and effective method for copper bonding using femtosecond laser-fabricated microscale tapers array and Ag–Zn–Cu intermetallic compounds as assistants is proposed. By the growth of intermetallic compounds among the microscale tapers array, the copper interfaces were firmly sintered. The cross section after shearing test was marked for analysis of sintering quality. Also, the shearing strength of interconnected copper interfaces under different bonding temperature, and holding times was investigated. The results show that the shearing strength can reach up to 120.1 MPa under 300 °C bonding temperature and 30 min holding time. According to the interconnected cross section and shearing strength test, the mechanism of increased shearing strength is explained. The experimental results show that the shearing strength of interconnected interface is greatly enhanced by the increase of contact area caused by microscale tapers array and the mechanical locking caused by the growth of intermetallic compounds. More possibilities could be provided by this technology in the field of electronic packaging interconnection and three-dimensional integrated circuits.

Passive cooling materials that spontaneously cool an object are promising choices for mitigating the global energy crisis. However, these cooling effects are usually weakened or lost when dust contaminates the surface structure, greatly restricting their applications. In this work, a robust hierarchical porous polytetrafluoroethylene (PTFE) film with coral-like micro/nanostructures is generated by a facile and efficient femtosecond laser ablation technique. Owing to its unique micro/nanostructures, the as-prepared surface exhibits an outstanding self-cleaning function for various liquids with ultralow adhesion. This self-cleaning characteristic enhances the durability of its passive cooling effect. It is demonstrated that the titanium (Ti) sheet covered with laser-ablated PTFE film can realize a maximum temperature decrease of 4 and 10 °C compared to the Ti sheet covered with pristine PTFE film and uncovered, respectively. This study reveals that femtosecond laser micromachining is a facile and feasible avenue to produce robust self-cleaning passive cooling devices.

The morphology of the weld seam, the formation mechanism of interface, and the microstructure and mechanical properties of both direct and AlSi12 (ER4047)-added dissimilar 5A06Al/Ti6Al4V lap joints were investigated, respectively. The Gibbs free energies of intermetallic compounds, such as TiAl3, TiAl, and Ti3Al, were calculated. The results showed that the interface layers were mainly composed of Ti3Al, TiAl, and TiAl3, and the order of them was TiAl3, TiAl, and Ti3Al from outside to inside. The addition of ER4047 interlayer could suppress the formation of IMCs and reduce the micro-cracks in TiAl3 layer. The ER4047-added joints featured good mechanical properties, i.e., the shear strength of 2087 N, 2405 N, and 2157 N respectively, which were much higher than the shear strength of 1721 N for the direct joint. Furthermore, the fracture model of the direct joint was brittle fracture, while that of the ER4047-added joints was quasi-cleavage. The results can provide theoretical guidance for the prediction of Ti/Al interface reaction and welding of other dissimilar metals.

The aluminum-steel hybrid assemblies would simultaneously reach the engineering aim to reduce weight and improve fuel efficiency. However, it is of great challenge to join aluminum to steel due to the great difference in thermal properties and the formation of IMC. In this work, a better joint between aluminum and Al-Si coated boron steel was successfully achieved using laser/DP-MIG hybrid welding-brazing. The examinations of welding appearance, macrostructure, interface microstructure, and tensile tests were carried out. The laser/DP-MIG hybrid welding-brazing could simultaneously strengthen metallurgic bonding and wettability compared to conventional MIG joint. The plasma characteristics of laser/DP-MIG hybrid source contributes to suppress the formation and growth of IMC. Three phases and its formation mechanism were demonstrated in detail: τ5-Fe2Al8Si, θ-Fe(Al,Si)3, and η-Fe2(Al,Si)5. The average joint strength of laser/DP-MIG was 271.8 N/mm whereas that of conventional MIG was 138.4 N/mm. The substantial adhesion area at the brazing interface and the brittle IMC is the two main factors in determining the tensile strength.

The Footprint of Uncertainty (FOU) for an Interval type-2 (IT2) input fuzzy set is a key parameter of IT2 fuzzy PI and PD (FPI and FPD) controllers because it provides additional options to handle uncertainties. Because the effects of FOUs on IT2 FPI and FPD controller are still unclear, it is necessary to provide a guideline for designing the FOUs. In this study, from the input–output relationship of IT2 FPI and FPD controllers using typical and popular configuration, the variation trend of variable gains, in relation to the increase of FOUs, was analyzed. It is mathematically proven that variable gains of typical controllers decrease or not increase as the FOUs increase. These theoretical results can be extended to provide a guideline for designing FOUs of typical IT2 FPI and FPD controllers. Real-time response of linear voice coil motor is used to show the effectiveness of our results.

In this research, amplitude Fresnel zone plates (FZPs) were fabricated on fused silica glass with femtosecond laser. The focusing characteristics including focal length, diffraction efficiency, geo...

Janus wettability membranes have received much attention because of their asymmetric surface wettability. On the basis of this distinctiveness from traditional symmetrical membranes, relevant scholars have been inspired to pursue many innovations utilizing such membranes. Femtosecond laser microfabrication shows many advantages, such as precision, short time, and environmental friendliness, over traditional fabrication methods. Now this has been applied in structuring Janus membranes by researchers. This review covers recent advances in femtosecond laser-structured Janus membranes with asymmetric surface wettability. The background in femtosecond laser-structured Janus membranes is first discussed, focusing on the Janus wettability membrane and femtosecond laser microfabrication. Then the applications of Janus membranes are introduced, which are divided into unidirectional fluid transport, oil-water separation, fog harvesting, and seawater desalination. Finally, based on femtosecond laser-structured Janus membranes, some existing problems are pointed out and future perspectives proposed.

Oxycodone is a common type of opioid used for the treatment of moderate to severe pain. Besides its analgesic effects on neuron cells, the effects of oxycodone on other cell types are yet to be elucidated. We previously demonstrated that oxycodone displayed both pro- and anti-cancer effects on bulk cancer cells. This work further investigated the effects of oxycodone on normal and malignant hematopoietic stem cells. Using hematopoietic CD34+ cells isolated from normal bone marrow (NBM) or patients with acute myeloid leukemia (AML), we showed that oxycodone activates hematopoietic cells regardless of cell development stage and malignant status. Oxycodone dose-dependently increases colony formation and self-renewal capacity of NBM and AML stem/progenitor cells, and promotes proliferation of AML bulk cells. NBM stem/progenitor cells are more sensitive to oxycodone than AML counterparts. In addition, oxycodone alleviates chemotherapy drug-induced toxicity in AML stem/progenitor cells. Mechanism studies demonstrate that oxycodone acts on hematopoietic cells in an opioid-receptor-independent manner. Oxycodone did not affect epithelial growth factor receptor (EGFR) signaling neither but stimulated Wnt/β-catenin signaling. Rescue studies via depleting β-catenin using genetic and pharmacological approaches confirmed that β-catenin was required for the activation of hematopoietic cells induced by oxycodone. Our work demonstrates 1) the protective role of oxycodone in malignant hematopoietic cells from chemotherapy; 2) stimulatory effects of oxycodone in normal hematopoietic stem cells; and 3) ability of oxycodone in Wnt signaling activation.

Femtosecond laser ablation is a flexible method for manufacturing gallium arsenide (GaAs) micro-optical components. However, its machining efficiency and surface quality do not satisfy industry req...

The fuzzy operator is one of the most important elements affecting the control performance of interval type-2 (IT2) fuzzy proportional-integral (PI) controllers. At present, the most popular fuzzy operators are product fuzzy operator and min() operator. However, the influence of these two different types of fuzzy operators on the IT2 fuzzy PI controllers is not clear. In this research, by studying the derived analytical structure of an IT2 fuzzy PI controller using typical configurations, it is proved mathematically that the variable gains, i.e., proportional and integral gains of typical IT2 fuzzy PI controllers using the min() operator are smaller than those using the product operator. Moreover, the study highlights that unlike the controllers based on the product operator, the controllers based on the min() operator have a simple analytical structure but provide more control laws. Real-time control experiments on a linear motor validate the theoretical results.

With the development of high performance processing system, high precision Permanent Magnet Linear Synchronous Motor (PMLSM) has been the focus of research. This paper provides a novel double-sided PMLSM with quasi- sinusoidal ring windings, to reduce the thrust ripple while keep the average thrust at a suitable value. Firstly, the distributions of the magnetic fields in this motor are analyzed, the low-order harmonics of armature magnetic field induced by the quasi- sinusoidal ring windings are studied, by equivalent magnetizing current (EMC) method. The winding factor and the Back Electromagnetic Force of this PMLSM are analyzed theoretically and verified by finite-element (FEM) method, based on the specific structure of quasi-sinusoidal ring windings. Furthermore, the electromagnetic thrust analysis is provided, which is aimed at the influence of the novel winding structure. Finally, a prototype of the double-sided PMLSM with quasi-sinusoidal ring windings is manufactured to verify the effectiveness of the topology proposed in this research. The presented results show that this novel motor can provide a great thrust property, it has a potential in high performance industry applications.

The working environment of Planar Lightwave Circuit (PLC) optical splitter is complex and diverse. In addition to withstanding the test of environmental temperature changes, the device may also be affected by mechanical shock such as vibration. Through the thermal-vibration coupling online test, it was found that the insertion loss of the PLC optical splitter changes significantly when the vibration test is performed under high temperature and low temperature environment (the maximum insertion loss change was 4.491dB at 75 °C, and 3.941dB at −40°C). In the same temperature environment, the optical performance of the device during the lateral test and the vertical test was more affected by vibration than in the horizontal test. The study of reliability under combined vibration and temperature fields is helpful to understand and improve the ability of devices to work normally in complex environments.

The study to obtain a sound joint between aluminum and steel is rather challenging due to the large mismatch in thermal properties and the formation of brittle IMCs, especially for press-hardened steel attributing to its martensite microstructure. In this present study, dissimilar joining of 5052 aluminum and press-hardened steel was comprehensively explored by employing laser offset welding without any fillers and interlayers. The influence of laser offset on welding appearance and mechanical properties was evaluated. The microstructure analysis, bonding mechanism, and fracture behavior were identified and characterized by means of optical microscope (OM), scanning electron microscope (SEM), energy-dispersive X-ray spectrometer (EDS), and X-ray diffraction (XRD). The satisfactory welding appearance and mechanical property of 129.6 MPa was obtained at the laser offset of 0.2 mm. The interface microstructure was composed of continuous Fe2Al5, acicular Fe4Al13 and islands IMCs. In addition, micro cracks could be initiated spontaneously in Fe2Al5 layer due to the residual stress, whereas a consecutive crack seems be induced by a micro pore defect. No matter what the fracture mode was during tensile test, the fracture surface was localized at the welded interface.

Cylindrical vibratory gyroscope is a kind of mode-matched gyros, and the frequency split would affect its sensitivity significantly. Frequency tuning is a major method to decrease the split. In the process of frequency tuning, the natural frequency should be measured firstly, and the measurement error is one of the decisive factor of tuning accuracy. Due to the measurement error of frequency is Normal Distribution, its effects on frequency tuning are studied by theoretical and simulation analysis from the statistical aspect. Firstly, the influence of frequency splitting on gyro sensitivity is studied, which shows the importance of reducing frequency splitting. Then the effect of different measuring accuracy on the measured value is analyzed. Thirdly, the tuning error that caused by the measurement error is researched in the process of trimming, and the tuning error is derived by theoretical analysis. Simulation and experiment results under different measurement error exemplify the value of tuning error. Finally, the optimal measurement accuracy that ensures achieving tuning accuracy is discussed.

Two-degree-of-freedom (2-DOF) actuators capable of producing linear/swing motion are significant for end-effectors in multidimensional complex motion platforms. This paper proposes a novel 2-DOF voice coil motor (VCM) featuring simple structure, small size, and great force properties. The structure of this novel VCM and the distribution of magnetic field are first described, the modeling of linear-thrust and swing-torque is accomplished, force properties of this 2-DOF VCM and stress analyses of the mover brackets are conducted by finite element method (FEM). Then, a prototype of this 2-DOF VCM was manufactured and tested to validate its theoretical features. In order to indicate the improvements of this proposed VCM, the force features of this motor are contrasted with the ones of a linear-swing VCM we designed previously; the simulation and experimental results of the two VCM are compared. Conclusion is drawn as that the proposed VCM has lower ripple ratios of linear-thrust and swing-torque, meanwhile, higher average values of linear-thrust and swing-torque are achieved. This paper provides a theoretical reference and experimental data of this novel 2-DOF VCM for multidimensional complex motion systems.

Cylindrical shell vibration gyroscope is a kind of solid wave gyroscope which uses the inertia effect of elastic wave to detect the rotation angular velocity. Precision dynamic balance is the key to improve the stability of gyro standing wave vibration. In this paper, precision dynamic mass-stiffness balancing along the working mode axis at the top of the resonator cup-wall is studied. The radial region of different trimming types and the variation of resonator natural frequency and frequency split with trimming hole depth are determined by the simulation. The femtosecond laser precision trimming-ablation experiment verifies the simulation results. The experiment and simulation have good consistency. This paper clearly clarifies the precision dynamic mass-stiffness balancing law of trimming along the working mode axis, which provides a guarantee for high efficiency and high precision trimming.

Beam shaping is required for semiconductor lasers to achieve high optical fiber coupling efficiency in many applications. But the positioning errors on optics may reduce beam shaping effects, and then lead to low optical fiber coupling efficiency. In this work, the positioning errors models for the single emitter laser diode beam shaping system are established. Moreover, the relationships between the errors and the beam shaping effect of each shapers are analysed. Subsequently, the relationship between the errors and the optical fiber coupling efficiency is analysed. The result shows that position errors in the Z axis direction on the fast axis collimator have the greatest influence on the shaping effect, followed by the position errors in the Z axis direction on the converging lens, which should be strictly suppressed in actual operation. Besides, the position errors have a significant influence on the optical fiber coupling efficiency and need to be avoided.

Precision linear motion is widely used in industrial application. For precision linear motion actuators, ripples of thrust force can deteriorate the driving performance and increase mechanical vibrations. It is very important to precisely test the thrust force of a linear motion actuator. This paper proposes a novel method based on testing reaction force and on the aerostatic method to achieve high-precision and universal testing capability. In this method, the mover and the stator of tested linear motion actuators are suspended by two air-bearing modules. In contrast to traditional testing methods, the force sensor is connected to the stator to avoid the influence of vibration on the sensor. The air-bearing modules eliminate the friction between the stator and the mover, so that it would not affect the results. To validate the strategy, a sample testing platform is manufactured, then a series of experiments is carried out, and the testing performance is compared with that of the traditional method. Experimental results demonstrate the high accuracy achieved by eliminating interferences due to friction and the vibration of the force sensor.

In this paper, one-step fabrication of fusiform hierarchical micro/nanostructures on copper surface by femtosecond laser is proposed. According to the preferential valley ablation, Marangoni effect based on melt hydrodynamics and the coupling of the incident light and surface plasmon polaritons, the formation mechanism of the fusiform hierarchical micro/nanostructures is explained. And the effect of laser parameters including the defocusing distance, laser power, and scanning speed on the surface morphology is investigated. Also, the quantitative analysis of the fusiform tapers is carried out. It is demonstrated that the three-dimensional size of the fusiform hierarchical micro/nanostructures could be controlled by adjusting laser parameters. In addition, the potential applications of the fusiform hierarchical micro/nanostructures in microliter droplet directional transportation and light absorption are explored.

A novel fiber inline Mach-Zehnder interferometer (MZI) is proposed for simultaneous measurement of curvature and temperature. The sensor composes of single mode-multimode-dispersion compensation-multimode-single mode fiber (MMF-DCF-MMF) structure, using the direct fusion technology. The experimental results show curvature sensitivities of −12.82 nm/m−1 and −14.42 nm/m−1 in the range of 0–0.65 m−1 for two resonant dips, as well as temperature sensitivities of 57.6 pm/°C and 74.3 pm/°C within the range of 20 °C–150 °C. In addition, the sensor has unique advantages of easy fabrication, low cost, high fringe visibility of 24dB, and high sensitivity, which shows a good application prospect in dual-parameters of sensing of curvature and temperature.

By means of the ABCD matrix relation under paraxial approximation, a simple method to calculate the coupling efficiency for laser diode coupling to cylindrical lensed fiber is presented. The allowable aperture is taken into consideration in our formalism. The mathematical model agrees excellently with earlier work. For the first time various coupling parameters are numerically optimized with the help of gradient method in order to make the coupling more efficient. A cylindrical lensed fiber coupling system is presented with a maximum coupling efficiency up to 94.23%. The effects of fiber tip radius and fiber core radius on coupling efficiency are also studied. Calculations presented in this study are executable by a pocket calculator. The results will guide the design of cylindrical lensed fiber coupling systems.

We have demonstrated a high-sensitivity strain sensor based on a novel photonic crystal fiber (PCF) interferometer by means of splicing two sections of thin core fibers (TCF) with a piece of PCF between two single mode fibers (SMFs). The proposed MZI has exhibited an excellent fringe visibility as high as 21 dB in air. Particularly, the measurement range was up to 4 me and a strain sensitivity of −1.89 pm/µe was achieved. It was found that the strain sensitivity of the MZI was weekly dependent on the PCF length. The measured sensitivities of the MZI with 25 mm, 30 mm and 35 mm PCF at ∼1590 nm were −1.83 pm/µe, −1.85 pm/µe and −1.77 pm/µe, respectively. Moreover, the temperature characteristics of the sensor were also investigated. Additionally, the sensor has advantages of simplicity of fabrication, low cost, compact size as well as large strain measurement range.