Traditional auxiliary power supply bidirectional DC/DC converter in hydrogen electric hybrid vehicle has the problems of high power tube loss and reverse recovery of parasitic diode. In order to solve these problems, this paper first improves its topology, adopts a non-isolated bidirectional Buck/Boost topology, and makes its two power switch tubes complementary on when working, realizes the zero voltage conduction of the power tube, and inhibits the reverse recovery of the parasitic diode of the power tube. Secondly, the analytical model of the converter is established by the modified state average method, and the two power switch tubes are uniformly controlled by the complementary control mode, which ensures the stable operation of the two-way flow of energy of the system. By using the built 1.2 Kw experimental prototype to verify, the obtained experimental waveform and data verify that the converter realizes soft switching, reduces power loss and improves conversion efficiency.

In view of the fact that the existing OTDR (Optical Time-Domain Reflectometry) system is difficult to meet the requirements of high resolution and long distance sensing, based on the optical time domain reflectometer, this paper studies the factors affecting the performance of the system by analyzingBOTDR (Brillouin Optical Time-Domain Reflectometry) technology, by means of the time-varying Markoffchain model, combined with the compilation of the time-varying Markoff chain model, an code sequencepulse light technology is proposed to optimize the signal-to-noise ratio of BOTDR system. This method canrealize the long distance sensing under the condition of low detecting light power, and improve the accuracyof the sensing system by improving the data fitting method. Finally, the practicability and effectiveness ofthe method is verified by experiments..Keywords- OTDR, optical time domain

Neoadjuvant chemotherapy (NAC) is the widely Immune checkpoint inaccepted treatment strategy for locally advanced ESCC and has been used in the past decades to downstage and improve the surgical resection rate for this malignancy. Immune checkpoint inhibitors (ICIs) have been shown to be efficient for advanced ESCC, while few studies focus on the neoadjuvant combination of immunotherapy and chemotherapy. To this end, we designed a trial to evaluate the safety and efficacy of toripalimab, a PD-1 inhibitor, combined with nab-paclitaxel (nab-P) and S-1 followed by radical resection surgery for resectable ESCC.

In order to simulate the target echo energy of semi-active laser guidance in actual combat environment, an injection laser energy simulation device was designed and developed. The laser-guided energy transfer process and simulation techniques were researched. First of all, aiming at the working process of laser guided weapons, the laser scattering and attenuation model in the atmosphere were established. Fog, rainfall, and interference smoke existing in actual combat were modeled and simulated. Then, the overall scheme of the laser target echo energy simulator was proposed. The DPS-A laser and Brewster angle polarizer were used to simulate the laser attenuation. A fiber coupling and uniform light collimation system was designed. Finally, a laser-guided semi-physical simulation system was constructed, laser echo energy simulation experiments, seeker calibration and laser terminal guidance experiments were performed, respectively. The results show that laser energy simulation error is less than 3%, the residual error within the linear range of the seeker is less than 0. 08, the accuracy of angle measurement is less than 0. 45 mrad, and the tracking error of line-of-sight angle in the terminal guidance process is less than 0. 2. The system can simulate laser energy transmission in a variety of real-world environments with high accuracy, which can meet the requirements of laser-guided semi physical simulation.

Heavy vehicle brake system controlled by electron-hydraulic servo is analyzed and designed in this paper. Considered the high speed, heavy weight and quick brake of heavy vehicle, the schemes of double pipeline brake that double chamber in brake cylinder controlled by dual brake valve used electron-hydraulic servo control is adopted in the brake system which can accomplish steering brake and emergent brake for heavy vehicle. Based on analyzed the influence of composed unit and linked pipeline to brake performance, the nonlinear mathematic model is developed for the brake system. The double pipeline steering brake is discussed by simulation experiment. The simulation results proved the rationality to develop the double pipeline brake system. Moreover the test-bed control experiments for the brake system of heavy vehicle are carried out, the experimental data prove that the brake performance achieve the design request.