Prediction and driving factors of forest fire occurrence in Jilin Province,China

Forest fires are natural disasters that can occur suddenly and can be very damaging,burning thousands of square kilometers.Prevention is better than suppression and prediction models of forest fire occurrence have developed from the logistic regression model,the geographical weighted logistic regression model,the Lasso regression model,the random forest model,and the support vector machine model based on historical forest fire data from 2000 to 2019 in Jilin Province.The models,along with a distribution map are presented in this paper to provide a theoretical basis for forest fire management in this area.Existing studies show that the prediction accuracies of the two machine learning models are higher than those of the three generalized linear regression models.The accuracies of the random forest model,the support vector machine model,geographical weighted logistic regression model,the Lasso regression model,and logistic model were 88.7%,87.7%,86.0%,85.0%and 84.6%,respectively.Weather is the main factor affecting forest fires,while the impacts of topography factors,human and social-economic factors on fire occurrence were similar.

Four driving forces for the advance of dyeing and printing equipment

The year of 2017 saw an obvious improvement in the sector of China’s textile machinery industry and an increase of the main business income and gross profit.Besides,foreign trade in textile machinery products grew in number.

An Example of Machine Vision Applied in Printing Quality Checking——Research on the Checking of Printing Quality by Image Processing

The traditional printing checking method always uses printing control strips,but the results are not very well in repeatability and stability. In this paper,the checking methods for printing quality basing on image are taken as research objects. On the base of the traditional checking methods of printing quality,combining the method and theory of digital image processing with printing theory in the new domain of image quality checking,it constitute the checking system of printing quality by image processing,and expound the theory design and the model of this system. This is an application of machine vision. It uses the high resolution industrial CCD(Charge Coupled Device) colorful camera. It can display the real-time photographs on the monitor,and input the video signal to the image gathering card,and then the image data transmits through the computer PCI bus to the memory. At the same time,the system carries on processing and data analysis. This method is proved by experiments. The experiments are mainly about the data conversion of image and ink limit show of printing.

Role of three-dimensional printing and artificial intelligence in the management of hepatocellular carcinoma:Challenges and opportunities

Hepatocellular carcinoma(HCC)constitutes the fifth most frequent malignancy worldwide and the third most frequent cause of cancer-related deaths.Currently,treatment selection is based on the stage of the disease.Emerging fields such as three-dimensional(3D)printing,3D bioprinting,artificial intelligence(AI),and machine learning(ML)could lead to evidence-based,individualized management of HCC.In this review,we comprehensively report the current applications of 3D printing,3D bioprinting,and AI/ML-based models in HCC management;we outline the significant challenges to the broad use of these novel technologies in the clinical setting with the goal of identifying means to overcome them,and finally,we discuss the opportunities that arise from these applications.Notably,regarding 3D printing and bioprinting-related challenges,we elaborate on cost and cost-effectiveness,cell sourcing,cell viability,safety,accessibility,regulation,and legal and ethical concerns.Similarly,regarding AI/ML-related challenges,we elaborate on intellectual property,liability,intrinsic biases,data protection,cybersecurity,ethical challenges,and transparency.Our findings show that AI and 3D printing applications in HCC management and healthcare,in general,are steadily expanding;thus,these technologies will be integrated into the clinical setting sooner or later.Therefore,we believe that physicians need to become familiar with these technologies and prepare to engage with them constructively.

Profibus-DP总线在印染拉幅定形机电气控制系统上的应用

对印染拉幅定形机的电气控制系统进行概述。该系统采用先进的西门子Profibus-DP总线通信技术,配备丹佛斯FC302变频器构成速度闭环控制方式。通过信号级联输出方式,实现各传动单元之间的速度同步,提高速度信号的实时性和精确度。此外,介绍了风机变频器和温控表所采用的Modbus总线通信方式,该通信方式实现了更好的设备数据整合与数据交换。

Load-sharing Characteristic of Multiple Pinions Driving in Tunneling Boring Machine

The failure of the key parts, such as gears, in cutter head driving system of tunneling boring machine has not been properly solved under the interaction of driving motors asynchronously and wave tunneling torque load. A dynamic model of multi-gear driving system is established considering the inertia effects of driving mechanism and cutter head as well as the bending-torsional coupling. By taking into account the nonlinear coupling factors between ring gear and multiple pinions, the influence for meshing angle by bending-torsional coupling and the dynamic load-sharing characteristic of multiple pinions driving are analyzed. Load-sharing coefficients at different rotating cutter head speeds and input torques are presented. Numerical results indicate that the load-sharing coefficients can reach up to 1.2-1.3. A simulated experimental platform of the multiple pinions driving is carried out and the torque distributions under the step load in driving shaft of pinions are measured. The imbalance of torque distribution of pinions is verified and the load-sharing coefficients in each pinion can reach 1.262. The results of simulation and test are similar, which shows the correctness of theoretical model. A loop coupling control method is put forward based on current torque master slave control method. The imbalance of the multiple pinions driving in cutter head driving system of tunneling boring machine can be greatly decreased and the load-sharing coefficients can be reduced to 1.051 by using the loop coupling control method. The proposed research provides an effective solution to the imbalance of torque distribution and synchronous control method for multiple pinions driving of TBM.

Evaluation of driving behavior based on massive vehicle trajectory data

Based on the driver surveillance video data and controller area network(CAN)data,the methods of studying commercial vehicles’driving behavior is relatively advanced.However,these methods have difficulty in covering private vehicles.Naturalistic driving studies have disadvantages of small sample size and high cost,one new driving behavior evaluation method using massive vehicle trajectory data is put forward.An automatic encoding machine is used to reduce the noise of raw data,and then driving dynamics and self-organizing mapping(SOM)classification are used to give thresholds or the judgement method of overspeed,rapid speed change,rapid turning and rapid lane changing.The proportion of different driving behaviors and typical dangerous driving behaviors is calculated,then the temporal and spatial distribution of drivers’driving behavior and the driving behavior characteristics on typical roads are analyzed.Driving behaviors on accident-prone road sections and normal road sections are compared.Results show that in Shenzhen,frequent lane changing and overspeed are the most common unsafe driving behaviors;16.1%drivers have relatively aggressive driving behavior;the proportion of dangerous driving behavior is higher outside the original economic special zone;dangerous driving behavior is highly correlated with traffic accident frequency.

Design Research on Drive System of Underwater Tapping Machine

The underwater tapping machine is composed of a center bit, a tapping cutter, a seal box, a main drive box, a boring bar assembly, a envelop, a gear case, a counter and so on. The drive system in underwater tapping machine consists of a worm drive, a gear drive system and a screw drive. The worm drive is in the main drive box. The worm is connected with a hydraulic motor and driven by the hydraulic motor. The gear drive system is a combined gear train which is the combinations of the fixed axes and differential gear train in the gear case. On the one hand, by means of the fixed axes gear trains the turn and power of transmission shaft are transferred to the boring bar and the screw rod, causing differential turn between the boring bar and the screw rod. On the other hand, the turns of the boring bar and the screw rod are transferred to the differential gear train. The differential gear train is used to drive a special counter to count axial travel of the boring bar. The screw drive is composed of a feed screw and a nut on the boring bar. There is the differential turn between the boring bar and the feed screw. By means of the nut, the boring bar can feed automatically. With the movement of the sliding gear 7 in the gear case, the designed drive system can also be provided with the ability of fast forward and fast backward movement of the boring bar in its idle motion, resulting in the increase of the tapping efficiency.

Research on HCI Prototype Design of Ink Automatic Control System for Offset Printer

In order to solve the low efficiency and poor precision problems of traditional ink control methods on domestic offset printers,developing modern ink automatic control system has become more and more urgent.As an important subsystem,the hu- man computer interface (HCI) is a key function for the wholly automatic control.Once this goal is obtained,all the printing pro- cedures especially the automatic control of ink volume should be finished with human computer interface in different areas.consid- ering the HCI design theory and structure characteristics of domestic printers comprehensively,the HCI prototype for automatic ink control system has been developed based on Visual Basic platform.As the individual ink key is instead of the integrated key,the di- vision result of ink fountain can be displayed on the interface.Through the interface,the dynamic adjusting functions such as mod- ifying ink volume,locking or unlocking each ink key and real-time displaying the adjusting results etc.can be completed.The sim- ulation test has shown that the opening and practical feature of the prototype is satisfactory.

Robust Multiobjective and Multidisciplinary Design Optimization of Electrical Drive Systems

Design and optimization of electrical drive systems often involve simultaneous consideration of multiple objectives that usually contradict to each other and multiple disciplines that normally coupled to each other.This paper aims to present efficient system-level multiobjective optimization methods for the multidisciplinary design optimization of electrical drive systems.From the perspective of quality control,deterministic and robust approaches will be investigated for the development of the optimization models for the proposed methods.Meanwhile,two approximation methods,Kriging model and Taylor expansion are employed to decrease the computation/simulation cost.To illustrate the advantages of the proposed methods,a drive system with a permanent magnet synchronous motor driven by a field oriented control system is investigated.Deterministic and robust Pareto optimal solutions are presented and compared in terms of several steady-state and dynamic performances(like average torque and speed overshoot)of the drive system.The robust multiobjective optimization method can produce optimal Pareto solutions with high manufacturing quality for the drive system.

A Review of Drive Techniques for Multiphase Machines

Multiphase machines are gaining increasing popularity because of their distinct advantages over three-phase counterparts,such as reduced per phase power rating,improved reliability and increased degrees of freedom.This paper overviews the development history of multiphase machines and drive techniques in Section II.Three kinds of drive algorithms,including Field-Oriented Control(FOC),Direct Torque Control(DTC)and Model Predictive Control(MPC),are introduced in Section III.Then two types of fault-tolerant methods are compared in Section IV,which are the Vector Space Decomposition(VSD)strategy and Optimal Current Control(OCC)method.Furthermore,different types of existing multiphase converter topologies are listed in Section V,and various kinds of multiphase PWM methods are discussed in Section VI.Finally,based on the review,developing trends of multiphase drive techniques are forecasted.

DYNAMICS OF THE LOOPER DRIVE MECHANISM ON A BLIND STITCHING MACHINE

The looper drive mechanism is a main moving part in the blind stitching machine, which is aspatial 5 bar RRRSR linkage. In this paper, a dynamic analysis of the looper drive mechanism is made by means of the ma-trix method. Two methods are adopted in the calculation of the shaking force and shaking moment, one isdone by the constraint reaction of the flame-connected kinematic parts; the other is the inertialforces of all moving links.

Dynamic Analysis on the Main Transmission Device of Wooden Ice Cream Sticks Branding Machine

In order to reduce the labor intensity,improve the production efficiency and enhance the equipment stability and the branding accuracy of the pattern,we have completed a double-row high-efficiency wooden ice cream stick branding machine structural design.The rigid-flexible coupling dynamics model is established and the movement and stress of the first-stage chain drive are calculated and analyzed.The comparison of the theoretical calculation results shows that the dynamic modeling and the structural design of the equipment are reasonable and the result of dynamic calculation also provides the basis of load data for dynamic strength calculation of structural components.

Modeling and TOPSIS-GRA Algorithm for Autonomous Driving Decision-Making Under 5G-V2X Infrastructure

This paper is to explore the problems of intelligent connected vehicles(ICVs)autonomous driving decision-making under a 5G-V2X structured road environment.Through literature review and interviews with autonomous driving practitioners,this paper firstly puts forward a logical framework for designing a cerebrum-like autonomous driving system.Secondly,situated on this framework,it builds a hierarchical finite state machine(HFSM)model as well as a TOPSIS-GRA algorithm for making ICV autonomous driving decisions by employing a data fusion approach between the entropy weight method(EWM)and analytic hierarchy process method(AHP)and by employing a model fusion approach between the technique for order preference by similarity to an ideal solution(TOPSIS)and grey relational analysis(GRA).The HFSM model is composed of two layers:the global FSM model and the local FSM model.The decision of the former acts as partial input information of the latter and the result of the latter is sent forward to the local pathplanning module,meanwhile pulsating feedback to the former as real-time refresh data.To identify different traffic scenarios in a cerebrum-like way,the global FSM model is designed as 7 driving behavior states and 17 driving characteristic events,and the local FSM model is designed as 16 states and 8 characteristic events.In respect to designing a cerebrum-like algorithm for state transition,this paper firstly fuses AHP weight and EWM weight at their output layer to generate a synthetic weight coefficient for each characteristic event;then,it further fuses TOPSIS method and GRA method at the model building layer to obtain the implementable order of state transition.To verify the feasibility,reliability,and safety of theHFSMmodel aswell as its TOPSISGRA state transition algorithm,this paper elaborates on a series of simulative experiments conducted on the PreScan8.50 platform.The results display that the accuracy of obstacle detection gets 98%,lane line prediction is beyond 70 m,the speed of collision avoidance is higher than 45 km/h,the distance of collision avoidance is less than 5 m,path planning time for obstacle avoidance is averagely less than 50 ms,and brake deceleration is controlled under 6 m/s2.These technical indexes support that the driving states set and characteristic events set for the HFSM model as well as its TOPSIS-GRA algorithm may bring about cerebrum-like decision-making effectiveness for ICV autonomous driving under 5G-V2X intelligent road infrastructure.

机耕道自动驾驶农机局部路径规划

针对机耕道场景下自动驾驶农机行驶的安全性、平稳性与规划实时性的实际需求,该研究提出了一种基于二次规划的局部路径规划方法。首先基于有限状态机构建农机机耕道行驶模式,其次采用横纵向解耦的方法,通过改进状态栅格法分别对农机速度行为和轨迹行为进行决策,随后利用二次规划方法生成满足多目标、多约束条件的农机轨迹和速度,得到最优路径,最后在多种行驶环境中进行仿真和实车试验,行驶参考速度为2 m/s。实车试验结果表明,在绕行静态障碍物场景中,规划轨迹的平均绝对曲率为0.021 m^(-1),最大绝对曲率为0.056 m^(-1),平均绝对横向误差为3.23 cm,最大绝对横向误差为8.69 cm,农机与障碍物外轮廓的距离大于0.76 m;在规避相向行驶、同向行驶和横穿机耕道的动态障碍物场景中,规划速度的平均绝对速度误差为0.08~0.12 m/s,绝对速度误差小于0.38 m/s,加速度变化范围为-0.38~0.44 m/s^(2)。在规划周期为200 ms的仿真试验中,该文算法平均耗时48 ms,最大耗时75 ms,相比采用静态状态栅格法平均耗时减少38 ms,算法效率提升44%。研究结果可为机耕道场景下的农机局部路径规划提供技术支持。

CYLINDRICAL WORM MACHINED BY THE CONE GRINDING WHEEL WITH TWO DEGREE－OF－FREEDOM AND MESHING THEORY OF ITS DRIVE①

The characteristics of novel cone-generated cylindrical worm and the machining princi- ple of using a grinding wheel with two degree-of-freedom motions are described. A systematic study is made on the first enveloping process of the grinding wheel forming a worm and the second enveloping process of the worm forming a worm wheel with the meshing theory of kinematic method. Some numerical calculation formulas and important conclusions are obtained.

数据驱动的中温隔热陶瓷管件结构优化设计及性能评估

随着中温区电加热的电子产品和家电用品不断涌现,低成本的高效保温隔热材料研究日益成为热点。如何确保管路内部快速升温并避免外表温度大幅波动,有效提高能源利用率,是保温隔热材料领域的挑战。据此,本研究以低熔点玻璃助烧结的镁橄榄石、莫来石、珍珠岩和磷酸锌等复合物陶瓷为对象,从数据驱动的壁内多孔结构隔热管件优化设计出发,开展陶瓷隔热管件三维打印制造,通过显微结构和力学性能分析,并围绕管件的导热、隔热影响因素评估,系统考察了该类新型隔热管件的理化、力学和隔热性能及影响关系。结果表明,通过对沿管壁环绕的矩形大孔高度调控(400~1 200μm)、管腔内热源区的管壁倍增(1.2 mm×2 mm)以及有机微球造孔剂引入(~9%),同时通过烧结温度控制(700~750℃),可以显著改善热流出口区的温度水平(~20℃),并显著优于不锈钢真空隔热管的出口温度。研究结果表明,增材制造复合陶瓷管件具有优良的综合性能以及较低的原料成本,使得多孔陶瓷隔热管件在中温隔热领域具有广阔的应用前景。

跟驰事件下网联混驾编队的运行特征及生态安全影响

考虑当前自动驾驶技术成熟度和公众接受程度等问题,网联混驾编队模式可能是自动驾驶编队全面普及应用前的可行的过渡模式之一。为研究网联条件和车队形式对网联混驾编队运行特征及生态安全的影响,文中基于驾驶模拟技术搭建的网联混驾编队实验测试平台,构建由5辆车组成的“领航车-网联L2级人工驾驶车辆、跟驰车-网联自动驾驶车辆”的网联混驾编队模式,并邀请36名被试开展驾驶模拟实验。考虑时域分析侧重呈现指标的时间维度变化,而频域分析可以挖掘指标的频率分布特性,文中选取速度、加速度指标从时域和频域维度分析车辆运行特征,同时选取油耗、速度安全熵指标评价车辆运行的生态安全性。结果表明:网联条件和编队模式均有助于车辆行驶更加平稳,并显著提升其生态安全性;网联混驾编队的综合效能最佳,相较传统单车模式,油耗可降低10.67%,速度安全熵值可降低73.25%。该研究成果可为自动驾驶企业及行业开展网联人机交互终端设计、领航驾驶辅助系统研发、网联混驾编队可行性及有效性测试等提供方案借鉴和平台支持。

草原公路驾驶接管风险的模糊推理评估方法研究

为探究草原公路行车场景和非驾驶相关任务对驾驶人接管过程的影响,提出了基于生理特性和接管绩效的模糊逻辑风险评估方法。首先,模拟牛羊出没、前方停车、匝道来车三种草原公路典型场景,并考虑在模拟场景下执行无次任务、听新闻、看视频、玩游戏四种非驾驶相关任务;其次,构建基于生理指标(心率变异性)和接管绩效(接管时间、接管质量)的风险评估指标体系;最后,采用模糊推理建立风险评估模型,量化评价不同场景和非驾驶相关任务组合的风险水平。结果表明,匝道来车场景和玩游戏在驾驶接管风险等级中被评估为高风险和极高风险占比较高。整体而言,高风险和极高风险样本占比达44.2%,反映出草原公路特定场景下执行感官参与维度多的任务具有较高的接管风险隐患。场景和非驾驶相关任务存在交互作用,在复杂场景下从事感官参与维度较高的任务极易导致高风险情况。相较于简单场景,驾驶人在复杂场景中的风险累积更快、波动更大,并在中后段达到峰值。

3D打印膝关节曲面磨粒流抛光数值模拟及实验研究

目的解决磨粒流加工3D打印制造的TC4钛合金膝关节时存在配合端面抛光效率低以及表面质量不均匀的问题。方法运用FLUENT软件并结合非牛顿流体的Carreau-Yasuda方程对有、无仿形工装的磨粒流加工3D打印膝关节进行对比分析,研究仿形工装对磨粒流加工的影响规律,并通过单因素实验确定颗粒直径倍数与流道间隙大小的关系,从而完成最佳仿形工装设计。结果仿真对比分析结果表明,仿形工装有助于减小压力损失,并且膝关节表面的切削量显著提升,最大提升了182.92%。同时,在双向磨粒流工艺下,膝关节表面切削量的不均匀程度平均降低73%,提升了表面质量的均匀性,证实了仿形工装的有效性。加工结果表明,当仿形流道间隙大小为5倍Si C颗粒直径、工作压力为2 MPa、加工时间为45 min、使用双向磨粒流工艺时,3D打印膝关节的整体表面粗糙度显著降低,平均表面粗糙度为0.67μm。主要配合曲面呈现镜面效果,表面粗糙度达0.38μm与0.46μm。结论当仿形工装的流道间隙为5倍SiC颗粒直径时,磨粒流抛光效果最优。采用双向磨粒流工艺,获得了优于单向磨粒流工艺的均匀表面压力,从而有效提升了表面质量的均匀性,为3D打印钛合金人工骨复杂曲端面的光整加工提供了理论参考和实验依据。