The Effect of Ignition Parameters on the Combustion Characteristics of an Aviation Piston Engine

A cylinder combustion simulation model was established for a two-stroke aviation piston engine used in a small unmanned aerial vehicle. The influence of different ignition system parameters on the combustion process of aviation kerosene was studied using this model. The research results showed that under the working conditions of 5500 r/min and 50% throttle opening, as the ignition energy increased, the peak values of average cylinder pressure and average temperature increased, and the combustion duration shortened, The advance of the combustion center of gravity increases the tendency of the engine to knock. Under the same operating conditions, as the ignition timing advances, the peak values of average pressure and average temperature in the cylinder increase, gradually approaching the top dead center, and the tendency of engine detonation increases more significantly.

Clinical Study on Adjuvant Chemotherapy of Cinobufacin Injection in Senior Patients with Colorectal Cancer

To investigate the clinical efficacy of adjuvant chemotherapy of cinobufacin injection in the treatment of senior patients with colorectal cancer and its influence on serum tumor markers and immune function,from November 2018 to November 2019,84 senior colorectal cancer patients in author's hospital were al randomly divided into control group and observation group,42 cases in each group,and the control group was treated with routine chemotherapy,the observation group was treated with routine chemotherapy and intravenous injection of cinobufacin,the two groups were all treated for 4 cycles,then the short-term efficacy,serum tumor markers[carbohydrate antigen 19-9(CA19-9),carbohydrate antigen 724(CA724),carcinoembryonic antigen(CEA)]and immune function indexes(CD3+,CD4+,CD4+/CD8+),as well as the unward reaction of chemotherapy were compared between the two groups before and after treatment.As results,Short-term efficacy:the total effective rate of observation group was significantly higher than that of control group(78.57%vs 47.62%,P<0.05).Tumor markers:after treatment,the levels of CA19-9,CA724 and CEA in the two groups were significantly lower than those before treatment(P<0.05).Compared between the two groups,the levels of each index in observation group were lower(P<0.05).Immune function after treatment the levels of CD3+,CD4+,CD4+/CD8+in observation group were significantly higher than those before treatment while the levels of CD3+,CD4+,CD4+/CD8+in control group were significantly lower(P<0.05).After treatment,the above each index in observation group were higher than those in control group(P<0.05).Untoward reaction:the incidence of leukopenia,thrombocytopenia,gastrointestinal response,fatigue and myelosuppresion in observation group were significantly lower than those in control group(P<0.05).The results show that cinobufacin injection in the adjuvant treatment of senior patients with colorectal cancer can improve the shortterm efficacy of chemotherapy,reduce the untoward reaction,and reduce the serum levels of CA19-9,CA724 and CEA,improve the immune function of the body,thus with high clinical application value.

Bionic Stepping Motors Driven by Piezoelectric Materials

By imitating the behavioral characteristics of some typical animals, researchers develop bionic stepping motors to extend the working range of piezoelectric materials and utilize their high accuracy advantage as well. A comprehensive review of the bionic stepping motors driven by piezoelectric materials is presented in this work. The main parts of stepping piezoelectric motors, including the feeding module, clamping module, and other critical components, are introduced elaborately. We classify the bionic stepping piezoelectric motors into inchworm motors, seal motors, and inertia motors depending on their main structure modules, and present the mutual transformation relationships among the three types. In terms of the relative position relationships among the main structure modules, each of the inchworm motors, seal motors, and inertia motors can further be divided into walker type, pusher type, and hybrid type. The configurations and working principles of all bionic stepping piezoelectric motors are reported, followed by a discussion of the advantages and disadvantages of the performance for each type. This work provides theoretical support and thoughtful insights for the understanding, analysis, design, and application of the bionic stepping piezoelectric motors.

Compression Behavior and Failure Mechanisms of Bionic Porous NiTi Structures Built via Selective Laser Melting

Inspired by the crystal microstructure of metals and the bamboo,the bionic porous NiTi structures with the porosities in the range of 75.8%–84.9%were built via selective laser melting(SLM).The compression behavior and the failure mechanisms of the porous NiTi structures were evaluated.It demonstrated an increase in the elastic modulus and ultimate strength when the porosity was decreased,from 3.06 to 7.66 GPa and from 34.1 to 147.6 MPa,respectively.The relationship between the elastic modulus and the porosity obtained by the finite element analysis exhibited similar tendency with the experiment,and agreed well with the Gibson-Ashby model’s prediction.Based on the theoretical model above and the observation of the deformation processing,the plastic deformation behavior and failure mechanisms of the SLMed porous NiTi structures were analyzed.

基于预激励磁场的无线电能传输绕组位置辨识方法

本文通过共用原边绕组产生直流磁场,为无线充电系统提出了一种精确的线圈定位方法。在对磁场的研究和对磁传感器布置的讨论的基础上,提出了包含磁芯放置系数G的位置方程,其中G代表磁芯对磁场的影响。在此基础上,通过判断磁场的零点,提出了可以适用于不同的充电板的G的自动识别方法。此外,本文给出了定位算法的流程图,该算法包括分区以提高定位精度。此外,所提出的定位系统己在1kW样机中使用,通过自动改变补偿电容,从而提高了错位的耐受性。

Design, Analysis and Experimental Performance of a Bionic Piezoelectric Rotary Actuator

This study presents a piezoelectric rotary actuator which is equipped with a bionic driving mechanism imitating the cen- tipede foot. The configuration and the operational principle are introduced in detail. The movement model is established to analyze the motion of the actuator. We establish a set of experimental system and corresponding experiments are conducted to evaluate the characteristics of the prototype. The results indicate that the prototype can be operated stably step by step and all steps have high reproducibility. The driving resolutions in forward and backward motions are 2.31 grad and 1.83 μrad, respectively. The prototype can also output a relatively accurate circular motion and the maximum output torques in forward and backward directions are 76.4 Nmm and 70.6 Nmm, respectively. Under driving frequency of 1 Hz, the maximum angular velocities in forward and backward directions are 1029.3 grad·s^-1 and 1165 μrad·s^-1 when the driving voltage is 120 V. Under driving voltage of 60 V, the angular velocities in forward and backward motions can be up to 235100 grad·s^-1 and 153650 μrad·s^-1 when the driving frequency is 1024 Hz. We can obtain the satisfactory angular velocity by choosing a proper driving voltage and frequency for the actuator.