Abstract:In the field of trace gas detection,tunable semiconductor laser absorption spectroscopy technology is rapidly devel-oping.Compared to traditional measurement methods,it has advantages such as non-intrusiveness,no need for frequent calibra-tion,high precision,and high sensitivity.Oxygen(O2)is crucial for human survival,production,and life.Detecting the concentra-tion of O2 is essential in safety protection,medical healthcare,combustion diagnostics,and other areas.This study uses semicon-ductor lasers,TDLAS technology,and direct absorption spectroscopy technology to measure the concentration of oxygen in the air.By using two absorption lines for measurement separately and comparing the experimental results,the accuracy and reliability of the experimental method and results are ensured.The HITRAN database is utilized to analyze the absorbance curves of O2 at six differ-ent concentrations under normal temperature and pressure conditions,this study analyzes the method of monitoring and early warn-ing of O2 concentration in the air using TDLAS technology.The final results show that the measurement system and method in this study have a good detection effect on O2 concentration and lay a certain foundation for its early warning analysis.

Abstract:A electrochromic temperature monitoring system integrating temperature sensors,STM32 control circuits,and elec-trochromic devices(ECD)is proposed to address the issues of bearing failure caused by extreme temperatures.The system uses an electrochromic device(ECD)as a visualization window to observe temperature changes,establishing a connection between the tem-perature changes of the bearings and the color changes of the devices.PT100 is used as a temperature sensor to detect the tempera-ture of the external environment.This paper uses STM32 as the main control core of the regulating circuit,and coordinates with ADC,DAC conversion circuits,and peripheral circuits to equivalently connect external temperature changes with color changes of ECD devices.Simultaneously it transmits the temperature detection value,ECD interface voltage,and monitoring screen to the up-per computer for real-time display.The use of this temperature detection system can comprehensively understand the temperature status of bearings during operation,and has high practical value and application prospects in bearing temperature measurement.

Abstract:MEMS vector hydrophones offer advantages such as small size,low cost,and good low-frequency performance.To achieve real-time transmission of the signals acquired by the hydrophone,this paper presents a wireless data transmission system for MEMS vector hydrophones based on FPGA.The system can detect the analog signals captured by the hydrophone in real time and perform digital processing.Meanwhile,it integrates an inertial navigation module to acquire the three-dimensional attitude an-gle data of the hydrophone.Practical tests show that the system successfully achieves complete data-link transmission within a range of 5 km.With its long-range wireless communication,high speed,reliable data storage,and high portability,the system provides an effective solution for the acquisition and storage of underwater acoustic source information and self-attitude information.

Abstract:In order to solve the problems of insufficient environmental information description and low mapping accuracy in the process of map construction using separate 2D LiDAR and RGBD cameras,this study proposes a SLAM algorithm based on infor-mation fusion of 2D LiDAR and RGBD cameras.Firstly,this paper obtains the camera's internal and external parameters through joint calibration,and establishes the conversion relationship between laser data and radar data.Secondly,time interpolation method is used to complete the laser frame at the corresponding visual frame,in order to achieve time synchronization of the two types of da-ta.Finally,a weighted error joint loss function is introduced to optimize the mapping and localization effects.The experimental re-sults show that in the testing of long corridor environments with single features and complex indoor environments,compared with a single SLAM,this algorithm has achieved significant improvement in both mapping and localization.Compared to laser SLAM,the positioning accuracy is improved by 17％,and compared to visual SLAM,the fusion accuracy is improved by 24％.

Abstract:The widespread application of offshore multi-module floating systems drives the development of their connectors.This article provides a review of the development status of existing connectors for offshore multi-module floating systems and briefly categorizes them.It also offers a concise analysis of the development trends in material selection and intelligentization for multi-mod-ule floating connectors.

Abstract:Aiming at the problem that the vibration of bearing outer ring is difficult to detect in real time under high tempera-ture rotating environment,a high temperature resistant wireless passive vibration accelerometer for in-situ measurement of bearing outer ring is designed in this paper.The eddy current electromagnetic coupling method is used to measure the vibration signal of the bearing surface by changing the distance between the eddy current probe coil and the metal bearing.Copper wire is used as the mate-rial to prepare high temperature resistant eddy current coil.The output signal of the designed high temperature resistant wireless pas-sive vibration sensor under 1 g～9 g acceleration excitation signal is verified on the vibration test platform.The results show that the output voltage signal of the sensor is linearly related to the input vibration signal.The sensitivity of the sensor is about 0.1549 mV/g,and the repeatability error is small.The wireless real-time detection of bearing outer ring vibration signal in high temperature envi-ronment can be realized.

Abstract:Aiming at the poor mixture of oil and gas in the cylinder of marine large-bore engine and the difficult ignition of nat-ural gas under lean burn,the simulation model of marine dual-fuel engine is established by CFD software to study the influence of diesel micro-injection ignition technology on marine engine performance.The results show that under the coupling of the two diesel injection parameters,advancing the diesel inject timing,increasing the injection angle,increasing the diesel nozzles number and increasing the injection pressure can improve the indicated thermal efficiency of the engine to a certain extent.In addition,advanc-ing the injection time and increasing the nozzles number have more obvious effects on improving oil and gas mixing and promoting combustion than increasing the injection angle and increasing the injection pressure.The coupling of diesel injection parameters is more beneficial to improve marine engine performance.

Abstract:Aiming at the optimization of the task allocation method of daily flight schedule,a daily flight schedule task alloca-tion model is established based on mixed integer programming,which is abstract to linear programming problem,solving the prob-lem of traditional daily flight schedule task allocation method mainly relying on experience.Finally,combining the case of a unit's task allocation method of daily flight schedule,the validity and practicability of this allocation method are verified.

Abstract:To solve the problem of UAV flight safety,a spectrum analysis system of UAV vibration information based on DSP is proposed,which collects and analyzes the UAV vibration signal in real time,records the vibration signal and analyzes its frequen-cy domain information,including the amplitude and phase of each frequency.It provides a variety of data interfaces,which can not only analyze the vibration spectrum characteristics in real time and upload the airborne link,but also provide data support for re-al-time monitoring of UAV flight status.It can also download and store the data afterwards to provide a practical basis for analyzing and evaluating the flight status of the UAV during the whole period.At the same time,the system uses four 5-order Nuttall window FFT algorithms to solve the spectrum leakage problem in vibration signal spectrum analysis,ensure the accuracy of the data,and greatly improve the reliability of the system.

Abstract:High dynamic range integrated magnetometers demonstrate extensive potential applications in fields involving com-plex varying magnetic fields such as biomagnetic measurements,nuclear magnetic resonance analysis,and smart grid systems.Therefore,this study proposes an innovative frequency tracking scheme,which continuously monitors the resonance frequency drift caused by time-varying magnetic fields and feeds it back to the microwave source in real-time.By adjusting the central frequency of the microwave source to expand its dynamic range,this scheme successfully extends the dynamic range to 6.4 mT,approximately 34 times that of the inherent dynamic range of diamond nitrogen-vacancy(NV)color centers.Additionally,the scheme achieves ef-ficient detection of rapidly changing magnetic field signals at 0.038 T/s.This research result provides strong support for the versatile applications of high dynamic range integrated magnetometers across multiple domains.

Abstract:In view of the limited wireless transmission distance in the current test and transmission scheme of explosion shock wave data,it is difficult to achieve long-distance real-time transmission.In this paper,a long-distance wireless transmission sys-tem based on high-speed serial port server is designed to realize the high-speed and reliable real-time transmission of explosion shock wave signal to the PC terminal outside the explosion field.In order to realize the continuous transparent transmission function of serial server without error code,a data receiving cache mode and data forwarding strategy are proposed.In order to realize high-speed and long-distance wireless transmission,pDDL900 with Ethernet communication interface is selected for wireless trans-mission,and the wireless transmission distance is tested several times by configuring transmission parameters.In order to adapt the speed of the serial port to the speed of the remote lower network port,the protection mechanism of the serial port receiving overflow is designed to improve transmission reliability.The test results show that the maximum baud rate of the serial port can reach 9 Mbps without error,the transmission distance can reach more than 4 km,and the transmission speed is 1 Mbps.It can improve the trans-mission speed and transmission distance,improve the stability and universality of the system.

Abstract:The rectification of distorted document images is an essential approach to enhance text recognition and information extraction accuracy,thereby promoting the intelligentization of documents.Existing methods for correcting distorted documents pri-marily focus on tightly cropped document images and are ineffective in addressing documents with significant environmental bound-aries.To address this issue,this paper proposes a distortion document correction method that involves detection before correction.Initially,improvements to the Mask R-CNN are introduced to enhance the accuracy of detecting blurry document images.This in-cludes the incorporation of a higher-resolution ROI Align layer and decoder layer,along with optimizations to the Mask module.Subsequently,precise correction of distorted documents is achieved by introducing offset field learning.Experimental results demon-strate notable performance on the Doc3DShade dataset compared to other state-of-the-art algorithms,with a 1.6％improvement in SSIM metric,a 0.5％decrease in LD metric,and a 5.42％reduction in character error rate.These findings substantiate its excep-tional performance and provide an efficient and accurate document correction solution for document capture on mobile devices.

Abstract:This paper introduces a new dung beetle algorithm developed in 2023,but the new algorithm also has its shortcom-ings,such as uneven initial population,easy to fall into local optimization,insufficient population diversity,and inaccurate conver-gence.Based on these problems,three improvement schemes,Singer chaotic mapping initial population location,variable spiral search strategy and Levy flight strategy,are proposed,and eight standard test functions are used to conduct simulation experiments and compare with GWO,SSA,WOA,NGO and the original DBO(Dung Beetle Algorithm).The simulation results show that after optimization and improvement,HDBO(Improved Dung Beetle Algorithm)has obvious advantages in terms of stability and conver-gence.

Abstract:This article analyzes the current development status of underwater acoustic beacons and provides prospects for fu-ture development.This article introduces the research status of two kinds of underwater acoustic beacon search platforms and the search systems and equipment they carry.This article analyzes three kinds of underwater acoustic beacon search methods and their current improvements and explorations.The paper provides prospects for the future development of underwater acoustic beacon search technology from two directions,which are improving search capabilities in various complex environments and developing search equipment towards industrialization,it provides reference for underwater acoustic beacon search work under different conditions.

Abstract:In response to the problems of long training time,slow convergence,and poor performance in some complex situa-tions in deep reinforcement learning in dynamic environments,a combination of multi-step bootstrap,perturbation fluid algorithm(IFDS),and deep deterministic policy gradient algorithm(DDPG)is proposed.Firstly,N-step Bootstrap is added to DDPG to en-dow the model with the ability to combine multiple future time steps.Secondly,the perturbation fluid algorithm is introduced to joint-ly construct a potential field with the velocity information of obstacles in the environment,solving the problem of high-dimensional continuous action space and improving training efficiency.Finally,an environment consisting of a single obstacle and multiple obsta-cles is constructed to simulate and validate the algorithm.The simulation results show that the improved DDPG algorithm has higher training stability and speed compared to traditional DDPG algorithms in the simulation environment,and it can successfully achieve dynamic obstacle avoidance in more complex environments.At the same time,the success rate of training is improved.

Abstract:Centerline extraction is a basic and critical step in line laser 3D scanning systems.In this paper,an algorithm for field programmable gate array(FPGA)is proposed to extract the laser centerline quickly and accurately.The algorithm is divided in-to three low-coupling modules for parallel coarse positioning,precise positioning and centerline interpolation modules.In the coarse positioning module,a sliding window is used to traverse all the pixel points in a column scanning manner to compute the local fea-tures of the image and detect the initial centroid of the laser line based on them.In the precise positioning module,a posi-tion-weighted grayscale gravity method is used to determine the location of the subpixel centroid.In the interpolation module,a hardware-friendly non-uniform linear interpolation method is proposed to improve the accuracy of the centerline in the horizontal di-rection.Experiments show that the algorithm is highly robust to subpixel accuracy extraction.By implementing the algorithm on FP-GA,high-speed and high-precision laser centerline extraction of 2.2 megapixel video streams at 1430 frames/sec is achieved.

Abstract:Aiming at the issue of blurriness and detail loss in outdoor images captured during rainy days,this paper proposes a single-image deraining algorithm that leverages convolutional neural networks(CNN)and Transformer technology.Initially,a fea-ture extraction module that combines the local modeling strengths of CNNs with the global context capturing ability of the Swin Trans-former is developed.Subsequently,incorporating contrastive constraint loss,a comprehensive loss function is proposed to optimize network training.When compared to prevailing deraining algorithms,the proposed solution not only removes rain streaks more effec-tively,but also retains image details more efficiently.

Abstract:The electrical mechanism of DC drift of langasite piezoelectric sensor during high temperature testing is analyzed in this work.The interactions among sensors,operational amplifier misalignments,passive components and electrical connections in the test environment are discussed.By establishing a simplified test loop model,the influence of chip devices and environmental fac-tors on output DC bias is deduced.The zero-drift suppression method is summarized according to the comprehensive influence ex-pression in the worst case,and the charge amplifier used for the high temperature test is optimized.After optimization,the test drift baseline at 800℃can be controlled to about 50％of the op amp supply rail,contributing>89.5％of the suppression effect com-pared with the uncompensated case.

Abstract:In engineering,three-dimensional potential flow theory is often used to describe the influence of floating platform on flow field.In frequency domain analysis,the wave force and related parameters under specific velocity potential are obtained by Bernoulli equation,and then the response of the floating platform under linear wave action is solved.In other words,the influence of regular wave on the amplitude of floating platform motion is studied.Then,the frequency domain response parameters are converted into time domain response parameters by Fourier transform,and the response characteristics of the floating platform under nonlinear wave action are revealed.This reflects the process that the floating platform produces motion response after being impacted by irregu-lar waves until it returns to the equilibrium state.

Abstract:Two artificial aging regimes,single aging and double aging,are developed to address the issue of strength reduc-tion in multi-pass MIG-welded joints made of 7N01-T4 aluminum alloy.The effects of the two artificial aging treatments on the mi-crostructure and mechanical properties of the joints are investigated.The results show that artificial aging treatments have minimal impact on the morphology of the metallographic structure in the fusion zone of the joint,and the microstructure essentially maintains its original appearance.After artificial aging treatments,the number of precipitated phases increases in the joint,while the acicular precipitates occur.The fracture of the joint changes from a mixed mode to a ductile mode after artificial aging.Both the hardness and impact toughness of the joint are significantly enhanced after the single aging.During the double aging process,the tensile strength and elongation of the joint increase by 8.2％and 15.6％,respectively,compared to those of the as-welded state.