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A rotor dynamic analysis method for the complex three-dimensional design blade was developed and applied to analyzing its aeroelastic stability. Based on the medium-size deformation beam theory and Hamilton principle, the joint transfer matrix was used in the blade kinematic and the deformation compatibility principle was used in the assembled finite element matrix to develop the complex three-dimensional rotor structural dynamics model. The BO105 rotor was used to validate this method and the aeroelastic characteristic of the complex three-dimensional rotor was analyzed in detail. The results showed that the negative structural coupling of flap-torsion was appeared with tip sweep, and the 1/rev torsion modal frequency was decreased, and the 1/rev torsion modal damping ratio was maximally decreased about 90%. The positive structural coupling of lag-torsion was appeared with tip droop, the 2/rev lag modal frequency was decreased, the 1/rev torsion modal damping ratio was maximally decreased about 62%. The torsion stability was sharply decreased with tip sweep and droop design.

基于准线性化隐式建模方法, 建立适用于大展弦比机翼的动力学模型, 研究分布式吊舱机翼的气动弹性特点。其中结构模型采用中等变形梁模型, 气动模型采用准定常理论, 利用小扰动和有限差分法, 建立求解机翼气弹稳定性的方法。在验证结构和气动模型准确性基础上, 研究吊舱的个数、质量、展向站位、弦向/法向偏置等参数对分布式吊舱机翼气动特性的影响。分析结果发现: 吊舱越靠近机翼中部、弦向和法向偏置越大机翼稳定性越高, 但质量分布不均时反而会降低稳定性; 机翼经历了振动收敛、单频简谐振动和倍频简谐振动, 其颤振形式为面内外弯曲和扭转耦合, 三维效应显著。文中的方法能够有效描述分布式吊舱机翼的气动弹性特性。

A vibration load computing method for a coaxial rigid rotor was developed and applied to analyzing its vibration load in rotor interference. The structural dynamics model based on the medium-size deformation beam theory and the double-rotor aerodynamics model that contains unsteady free wake were jointly used to develop the coaxial rigid rotor's vibration load computing method. The wind tunnel test data of the XH-59A helicopter was used to validate this computing method. The vibration load of a rotor hub was analyzed in detail. The results show that the 3Ω harmonic wave amplitude of the vertical force Fz of the rotor hub and that of its pitch moment My decrease in high pitch angle, but the 3Ω harmonic wave amplitude of the roll moment Mx of the rotor hub obviously increases. The vibration load of the rotor hub increases with the decrease of the range of the coaxial rigid rotor; the roll moment and pitch moment of the rotor hub are sensitive to phase angle. The results also show that the increase of the 3Ω harmonic wave amplitude of the roll moment Mx is greater than the decrease of that of the roll moment My at the phase angle of 30° and that the level of vibration load of the rotor hub is minimum at the phase angle of 0° in forward flight.

Objective To analyze the factors related to gallbladder cholesterol polyp (GCP) and gallbladder adenoma (GA) and establish predictive model for distinction between GCP and GA before surgery. Methods Patients with gallbladder polyps diameter≥10 mm diagnosed by ultrasonography in Xuanwu Hospital Capital Medical University and the First Hospital of Peking University from January 2015 to December 2019 were studied. There were GCP group and GA group based pathological diagnosis. Univariate and multivariate analyses were used to study the factors related to GCP and GA. Logistic linear regression was used to establish a predictive model and to evaluate the diagnostic effect. Results A total of 384 patients with gallbladder polyp were in this study with male to female ratio of 1:1.49 and age of (50.32±14.15) years. There were 250 patients (65.1%) in GCP group and 134 patients (34.9%) in GA group. Univariate analysis showed that five factors in quantitative data including age, blood glucose, low density lipoprotein, albumin, and total bile acid and three factors in count data including age 50 years or older, low density lipoprotein ≥3.1 mmol/L and total bile acid ≥10.0 μmol/L had significant difference statistically between two groups (P

For problems of short cycle life and high maintenance cost of existing power supply of domestic mine auxiliary transportation vehicle which uses lead-acid batteries as power supply, the paper proposed application of LiFeO4 battery to the mine vehicle. Firstly, characteristics of the lithium battery group was studied through analyzing influence of cell capacity and resistance characteristics on li-ion battery inconsistency, and then li-ion battery power supply system that can be used for the mine transportation vehicle was developed according to related security standard of coal mine, mainly including li-ion battery pack, battery management system and explosion-proof box. The test results of prototype show that the power supply system can be applied to a variety of auxiliary transportation vehicles, and can meet use requirements.

Two-dimensional (2D) organic semiconductor crystals are single crystal materials grown by self-assembly using intermolecular van der Waals forces. The intrinsically single crystal properties make it possess excellent electrical properties. More importantly, the enhanced interfacial properties in the 2D limit can greatly tune the device behaviors, providing the possibility to construct multifunctional interfacial devices. In addition, the exposed charge transport channel and few in-plane defects make it possible to study the intrinsic transport properties of organic electrons. At present, great progress has been made in the growth process of two-dimensional organic semiconductor crystals, however, the theoretical study of the self-assembly process of two-dimensional crystal growth is still very scarce. In this work, two-dimensional organic semiconductor crystals were successfully prepared by additive-assisted crystallization technology, the surface morphology and structure of the two-dimensional crystals were comprehensively characterized by polarized light microscopy and atomic force microscopy. For the mechanistic study of crystal growth, the SEM combined with EDS techniques were employed to study structural and compositional characterization of key nucleation interfaces. The results show that the growth material can nucleate stably at the additive interface, and it is calculated that the favorable interface constructed by the additive can reduce the nucleation barrier to 1/5 of that on the SiO2 interface. This work fully demonstrates the key role of the growth interface in crystal growth, and theoretically reveals the regulated behavior of the interface, that provides a reliable idea for the growth process design of two-dimensional organic semiconductor crystals. [ABSTRACT FROM AUTHOR]

Temporal interference (TI) as a new neuromodulation technique can be applied to non-invasive deep brain stimulation. In order to verify its effectiveness in the regulation of motor behavior in animals, this paper uses the TI method to focus the envelope electric field to the ventral posterior lateral nucleus (VPL) of the thalamus in the deep brain of mouse to regulate left- and right-turning motor behavior. The focusability of TI in the mouse VPL was analyzed by finite element method, and the focus area and volume were obtained by numerical calculation. A stimulator was used to generate TI current to stimulate the mouse VPL to verify the effectiveness of the TI stimulation method, and the accuracy of the focus location was further determined by c-Fos immunofluorescence experiments. The results showed that the electric field generated by TI stimulation was able to focus on the VPL nuclei when the stimulation current reached 800 μA; the mouse were able to make corresponding left and right turns according to the stimulation position; and the c-Fos positive cell markers in the VPL nuclei increased significantly after stimulation. This study confirms the feasibility of TI in regulating animal motor behavior and provides a non-invasive stimulation method for brain tissue for animal robots.

Power supply plays a key role in ensuring animal robots to obtain effective stimulation. To extending the stimulating time, there is a need to apply photovoltaic cells and monitor their parameter variations, which can help operators to obtain the optimal stimulation strategy. In this paper, an online monitoring system of photovoltaic cells for animal robot stimulators was presented. It was composed of battery information sampling circuit, multi-channel neural signal generator, power module and human-computer interaction interface. When the signal generator was working, remote navigation control of animal robot could be achieved, and the battery voltage, current, temperature and electricity information was collected through the battery information sampling circuit and displayed on the human-computer interaction system in real time. If there was any abnormal status, alarm would be activated. The battery parameters were obtained by charging and discharging test. The battery life under different light intensity and the stimulation effect of neural signal generator were tested. Results showed that the sampling errors of battery voltage, current and electric quantity were less than 15 mV, 5 mA and 6 mAh, respectively. Compared with the system without photovoltaic cells, the battery life was extended by 148% at the light intensity of 78 320 lx, solving the battery life problem to some extent. When animal robot was stimulated with this system, left and right turns could be controlled to complete with the success rate more than 80%. It will help researchers to optimize animal robot control strategies through the parameters obtained in this system.