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Optimum design is proven significant for improving task performances of robotic manipulators under certain constraints. However, when it is utilized for collaborative robots (Cobots), there are still many challenges such as complex smooth surface links, time-varying kinematic configurations, computational expensiveness, and nonstructural parameter optimization. Therefore, based on orthogonal design experiment (ODE) and finite element substructure method (FESM), a multi-objective optimum design method of Cobots is proposed with the structural dimensions and parameterized joint components as the optimization variables and the natural frequency, the Cartesian stiffness, and the mass of the robot as optimization objectives. Firstly, to obtain multiple global performance indexes (GPIs) of robots in real-time and efficiently, the FESM model of Cobots is established which can preserve the accuracy of the finite element method (FEM) while ensuring the computational efficiency. Then, the gray relational analysis method (GRAM) is used to construct the multi-objective optimization function which includes the global first-order natural frequency index (GFNFI), the global elastic deformation index (GEDI), and the mass of robots. The ODE is constructed, and the structural dimensions and parameterized joint components are taken as influencing factors. According to the orthogonal array (OA), the degree of gray incidence under different levels of influencing factors is solved. And the optimal combination of influencing factor levels is obtained by range analysis (RA), which is used to guide the design of Cobots. Finally, a Cobot SHIR5-I is taken as an illustrative example to perform optimum design in this paper.

In this paper, we report an impregnated type of tungstate dispenser cathode prepared by Ba5Sr(WO6)2. The direct-current (dc) and pulsed-current (pc) emission properties and their evaporation rates have been investigated compared with the traditional Ba-W dispenser cathodes. Experimental results show that the current densities of the impregnated tungstate cathodes are twice larger than that of a typical 6-1-2 aluminate cathode, e.g., the dc and pc emission densities of the tungstate cathode can reach up to 10.6 and 56.6 A/cm2 at $1050~^{\circ }\text{C}_{{\text {br}}}$ , respectively. The evaporation rate of the impregnated tungstate cathode is $2.02\times 10^{-{9}}\text{g}\cdot $ cm $^{-2}\cdot \text{s}^{-1}$ at $1050~^{\circ }\text{C}_{{\text {br}}}$ , which is only 54% as much as that of the aluminate cathode, as measured by a quartz crystal oscillating method. The work function model of the tungstate cathode was studied by ab initio density functional theory (DFT) calculation. It is found that free Ba is preferentially adsorbed on the hollow site of ZrO2-W (001), and on BaZrO3 (001) in a more stable way during operation, resulting from its fine emitting and evaporation characteristics.

In order to enhance output power and prolong lifetime of the high-power magnetron tubes, a novel Y 2 Hf 2 O 7 Ceramic cathode had been developed. The thermionic emission and lifetime characteristics of the Y 2 Hf 2 O 7 cathode had been measured. The results show that the cathode can provide 0.15A/cm2, 3.5A/cm2 current density for the space charge limitation at 1300 Cbr, 1600 °C br respectively under 300V anode voltage. The lifetime of the cathode is more than 4100 h with an initial load of 0.5A/cm2 at 1400Cbr.

Transparent and highly oriented 3C-SiC bulks were speedily fabricated at deposition temperature (Tdep) of 1623 K by halide laser chemical vapor deposition (HLCVD). The effect of total pressure (Ptot) on the optical transmittance, preferred orientation, microstructure, deposition rate (Rdep) and micro-hardness were investigated. The maximum Rdep of the transparent 3C-SiC reached 2450 μm/h at Ptot = 10 kPa. With an increase in Ptot, the transmittance of 3C-SiC bulks increased firstly, and then decreased. At Ptot = 10 kPa, 3C-SiC bulk, a highly -oriented and low density of defects, showed the highest transmittance, greater than 55% in the wavelength range of 800–1100 nm. At Ptot = 4 kPa and 20 kPa, 3C-SiC bulks showed much lower transmittance, in which contained poorly oriented grains and numerous defects. The Vickers micro-hardness of 3C-SiC bulks increased with increasing Ptot and showed the highest value of 34.8 GPa at Ptot = 40 kPa.

In order to improve the stiffness modeling accuracy, an extended stiffness modeling and identification method of a 7 degrees of freedom(Dofs) collaborative robot is introduced in this paper. Unlike the traditional stiffness model which is assumed that each actuated joint is presented by a single one-dimensional virtual spring, the compliance of links, bearings and other structural components are considered and equivalent to two virtual joints in this method. These two additional virtual joints are orthogonal to the rotation axis of actuated joints. Including the equivalent virtual joint of joint torsional stiffness, each actuated joint of the robot has three virtual joints eventually. The method extends the traditional virtual joint method(VJM) and opens new prospects in terms of the stiffness optimal synthesis. Meanwhile, the accuracy of stiffness modeling is improved. Based on a 7 Dofs collaborative robot SHIR5, the static compliance simulations are performed to identify the elastic parameters of the robot, and the results show that more precise Cartesian stiffness characteristics are obtained from the extended stiffness model. Finally, the influence of compliance of links, bearings and other structural components on the stiffness model of the robot are analyzed.

A W-Y alloy cathode applied in magnetron tube has been developed. The thermionic emission experimental results show that the dc thermionic characteristic curve of the cathode has been straight up at 1500° br with no space charge deviation point. The lifetime experimental results show that the thermionic emission current density of the cathode decreases linearly from the initial 1.5A/cm2 to 0.2A/cm2 after 80h lifetime testing at 1600° br.

In order to enhance the emission current, reduce the operating temperature and prolong the lifetime of the pure W filament cathode for application in high-power (i.e., more than 10KW) continuous wave magnetron tube, a novel Y2O 3 -Gd2O 3 -HfO 2 impregnated W base direct-heated cathode (Y-Gd-Hf-O impregnated cathode) has been developed. In this abstract, the thermionic emission mechanism of the Y-Gd-Hf-O impregnated cathode has been researched by SEM, EDS and AES.

Earth-abundant and low-cost hydrogen evolution reaction (HER) electrocatalysts represent a future direction for achieving sustainable hydrogen energy production. Low-cost amorphous molybdenum sulfides (MoSx), with their highly active HER activity, have emerged as outstanding catalysts for electrochemical hydrogen production. Herein, we report the development of a synergetic amorphous MoSx hybrid catalysts on V2O3 with optimized HER activity of MoSx. Our synthetic and structural characterization shows that MoSx distributes on V2O3 uniformly. HER-inert V2O3 provides a highly electrochemically active surface area for HER and promotes electron transport. The obtained hybrid MoSx/V2O3/CC catalyst exhibits a low overpotential of 146 mV at 10 mA cm−2 toward HER under acidic conditions, which is comparable with the current advanced catalysts, and high stability with no significant changes over 10 h of electrolysis. The density functional theory calculations also demonstrate that the interface of V2O3 and MoSx helps to improve the conductivity.

In order to enhance the emission current, reduce the operating temperature and prolong the lifetime of the pure W filament cathode for application in high-power (i.e., more than 10KW) continuous wave magnetron tube, a novel Y 2 O 3 -Gd 2 O 3 -HfO 2 impregnated W base direct-heated cathode (Y-Gd-Hf-O impregnated cathode) has been developed. At 1700°br, the dc emission density of the Y-Gd-Hf-O impregnated cathode can reach to 10.5A/cm2. After 3600 h operation of the cathode under 1600°br, the dc emission current density of it is still stable at the initial value of 1.5A/cm2.

In this paper we mainly describes the research progress in a kind of ammonium perrhenate impregnated W matrix Ba-W cathode, which includes the evaporation rate measuring and the lifetime testing of the cathode. The evaporation rate measuring results shows that the evaporation rate of the cathode is 8.66×10-10g.cm−2s−1 at 1000 °Cbr measured by a quartz crystal oscillating method. The lifetime testing results show that the emission current, after 22392h lifetime at a temperature of 1000 °Cbr, has still increased more than 6% of the initial 3.0 A/cm2 DC current density.

Tungstate cathodes have been prepared by impregnating a mixture of the barium-strontium tungstate and zirconium hydride at 1840 °C b . Emission characteristics and evaporation properties were tested. The result shows that the dc emission current density reaches 4.30A/cm2 at 1000 °C b , 7.54A/cm2 at 1050 °C b , 9.43A/cm2 at 1100 °C b . The evaporation rate of the cathode is lower than an uncoated aluminate cathode.

In order to enhance output power and prolong lifetime of the high-power continuous wave magnetron tubes, a novel Y 2 O 3 -Gd 2 O 3 -ZrO 2 impregnate W sponge layer directly heated cathode is researched. The testing results show that the DC emission density of the cathode can reach 3.58A/cm2 at a temperature of 1750°C. Lifetime experiment results show that the thermionic emission current density is still above 1.5A/cm2 after 2600h operation.

In order to enhance output power and prolong lifetime of the high-power continuous wave magnetron tubes, a novel La 2 Zr 2 O 7 impregnated cathode is adopted to enhance the thermionic emission. In this abstract, we compare the thermionic emission ability of this cathode with traditional pure W filament cathode. Experimental results show that this cathode can provide the same thermionic emission with at least 300 ° lower than pure W filament cathode.

In this paper we mainly describes the research progress in a kind of ammonium perrhenate impregnated W matrix Ba-W cathode, which includes the preparation of W-Re matrix by impregnated ammonium perrhenate solution and the cathode properties testing. The lifetime testing results show that the emission current, after 16056h lifetime at a temperature of 1000 °Cbr, has still increased more than 8% with 3.0 A/cm2 DC current.

Energy and local distribution of electron around the cathode have been simulated in a 30kW continuous wave magnetron tube which operates in normal output power. According to the simulation results, it is clearly that the cathode of magnetron is bombed by low energy electrons mostly among 0 and 2keV. Based on the fact that most of the back bombardment electron belong to low energy electron, when the energy of incident electron is among 0 and 2keV, the secondary electron emission yield (SEEY) of cathodes provided with different mass percent Re doping W-Re alloy are measured, eventually, we obtain the maximum SEEY of W-Re alloy cathode when adopted by 5%Re doping.