Modal Analysis of Thread off Failure of Oil Round Thread Casing Connection

The dynamic modal model analysis of the oil casing connection is done by finite element method (FEM), and the first nature frequency, the second nature frequency, the vibration mode shape and the time domain of the node displacement and the element stress variation in the thread connection are gotten. The Von.Mises stresses of the connection in the static and dynamic state are also studied. The results of calculation and analysis show: (1) because the maximum of static stress is at the coupling thread end of connection, the connection begins to thread off at the coupling thread end, which is in accord with the results of the thread off experiment in laboratory; (2) because the first nature frequency is very high, the probability of casing connection to be damaged from vibration is little; (3) the shock dynamic load makes casing connection begin to thread off at the tube thread end.

Roller Screw and Threaded Chain Speed Reducer: An Experimental Evaluation

We are developing a speed reducer that can be considered a transformation of a worm gear reducer: the worm is replaced by an inverted roller screw, and the gear is replaced by a threaded chain drive. This configuration lessens wear, increases load capacity, and improves efficiency. The threaded chain consists of nut-shaped links. This paper presents the results of tests carried out on a prototype with a reduction ratio of 46.

基于BL602的RT Thread移植方法研究

RT Thread是一款嵌入式实时操作系统,因其易于移植、可裁剪性好等特点备受广大嵌入式开发者的喜爱。BL602芯片内含一个32位的RISC V架构的微处理器,兼具高性能、超低功耗等特点。但目前关于将RT Thread实时操作系统移植到BL602芯片上还没有成熟的方案,针对这一现象,给出了将RT Thread移植到BL602上的详细方案。通过剪裁源码、修改配置文件、修改系统时钟、添加串口输出、采用轮询或中断回调实现串口输入等操作进行移植。实验结果表明,移植到BL602上的RT Thread操作系统可以正常运行,并且具备任务管理、任务调度等功能。本文提出的移植方案不仅可以降低BL602的开发难度、提高CPU的利用率,而且为其他RTOS移植提供了参考。

Summary and clinical application of Zhuang medicine medicated thread moxibustion

Zhuang medicine medicated thread moxibustion is a kind of external therapy with ethnic medicine characteristics that spreads in Guangxi Zhuang region.It has a wide range of clinical application and significant curative effect,and can be used to treat diseases such as internal medicine,surgery,dermatology,gynecology,pediatrics,and five sense organs.Through reviewing and combing the literature on the Zhuang medicine medicated thread moxibustion in recent years,this paper summarizes and prospects its clinical application,with a view to further explaining the basic principles and application rules of Zhuang medicine medicated thread moxibustion and digging its clinical value.

Security Threads and IoT Security

One of the technologies that have attracted the most attention recently across a variety of applications is the Internet of Things (IoT). The Internet of Things (IoT) is the combination of sensor, embedded computing, and communication technologies. The goal of the Internet of Things is to provide seamless services to anything, everywhere, at any time. The internet of things (IoT) technologies plays a vital role everywhere after the internet and information and communication technology, ushering in the fourth disruptive technology revolution (ICT). For real-time processing, communication, and monitoring, the smart items are linked together through wired or wireless connections. Implementing the IoT system presents security and privacy challenges since IoT devices are incompatible with current security standards based on tradition. This paper discusses IoT security strands, mitigation strategies, and privacy issues. This study’s major objective is to get more knowledge about security threats, mitigation techniques, and privacy concerns in IoT devices. The authors also mentioned a few cutting-edge technologies that can address general security problems. This study’s major objectives are to find research gaps in IoT security and match solution paradigms. The advent and rapid growth of the Internet of Things (IoT), which offers innumerable benefits, facilities, and applications including smart grids, smart homes, smart cities, and intelligent transportation systems (ITS), have an impact on everyone’s life. However, the deployment and use of sensing devices exposes IoT-based systems and applications to many security flaws and attacks. Furthermore, the lack of standardization brought on by the diversity of devices and technologies makes integrating security in the IoT a severe problem. The purpose of this review paper is to highlight the numerous security threats, challenges, and attacks that IoT-enabled applications face.

RT-Thread操作系统的电池管理系统设计

为了保证电池在充放电过程中的安全,针对目前电池管理系统存在可移植性差、不便于功能扩展等问题,提出一种智能电池管理系统。系统采用国产嵌入式实时操作系统RT-Thread,并选用STM32作为主控制器芯片,使整个系统的监控、调试更加方便。测试结果表明,该系统可以实时监控电池的充放电过程,预留的接口可以方便以后做功能扩展。

RT-Thread和Qt的可视化印花机控制系统设计

为了提高印花机控制系统的自动化水平,针对当前印花机控制系统功能单一、稳定性差、缺少直观的数据显示和命令操作界面等缺陷,提出一种基于上下位机模式的可视化印花机控制方案。该方案采用嵌入式实时操作系统RT-Thread实现下位机模块的任务调度,采用Qt应用程序框架设计上位机的人机交互图形界面,并通过CAN总线连接下位机进行印花电机的监控。实验证明,该方案不仅提高了系统的可靠性和操作的直观性,而且有利于系统的进一步改进与升级。

MSP432的RT Thread操作系统移植

RT Thread是一个组件丰富、功能强大、可裁剪性好的开源嵌入式操作系统,而MSP432兼具高性能和低功耗优点,在医疗、能源等领域应用广泛,两者结合必将使得开发更加高效、便捷。但是,关于RT Thread向MSP432单片机移植的详细过程尚未有现成方案。为此,本文给出了RT Thread操作系统在MSP432P401R上移植的具体方法,通过剪裁源码、修改配置文件、更改系统时钟等操作进行适配并移植。实验结果表明,RT Thread系统成功移植到MSP432并能正常运行,具备任务管理、调度以及中断及异常管理等功能。

RT-Thread的I^2C总线驱动结构分析、移植及应用

针对RT-Thread操作系统下I^2C总线驱动展开研究,对驱动结构进行介绍与分析。以STM32F407VG上的软件I2C驱动移植为例介绍了驱动移植步骤,并通过STM32F407VG读写24LC02B的实例,详细介绍I^2C编程步骤及技术细节。最后通过实验验证I^2C驱动移植及编程的有效性。实验结果表明,RT-Thread操作系统下的I^2C总线驱动结构简洁,且易于移植及进行程序设计。

Comprehensive Survey of the Landscape of Digital Twin Technologies and Their Diverse Applications

The concept of the digital twin,also known colloquially as the DT,is a fundamental principle within Industry 4.0 framework.In recent years,the concept of digital siblings has generated considerable academic and practical interest.However,academia and industry have used a variety of interpretations,and the scientific literature lacks a unified and consistent definition of this term.The purpose of this study is to systematically examine the definitional landscape of the digital twin concept as outlined in scholarly literature,beginning with its origins in the aerospace domain and extending to its contemporary interpretations in the manufacturing industry.Notably,this investigationwill focus on the research conducted on Industry 4.0 and smartmanufacturing,elucidating the diverse applications of digital twins in fields including aerospace,intelligentmanufacturing,intelligent transportation,and intelligent cities,among others.

Analysis of secondary makeup characteristics of drill collar joint and prediction of downhole equivalent impact torque of Well SDTK1

Based on the three-dimensional elastic-plastic finite element analysis of the 8"(203.2 mm)drill collar joint,this paper studies the mechanical characteristics of the pin and box of NC56 drill collar joints under complex load conditions,as well as the downhole secondary makeup features,and calculates the downhole equivalent impact torque with the relative offset at the shoulder of internal and external threads.On the basis of verifying the correctness of the calculation results by using measured results in Well GT1,the prediction model of the downhole equivalent impact torque is formed and applied in the first extra-deep well with a depth over 10000 m in China(Well SDTK1).The results indicate that under complex loads,the stress distribution in drill collar joints is uneven,with relatively higher von Mises stress at the shoulder and the threads close to the shoulder.For 203.2 mm drill collar joints pre-tightened according to the make-up torque recommended by American Petroleum Institute standards,when the downhole equivalent impact torque exceeds 65 kN·m,the preload balance of the joint is disrupted,leading to secondary make-up of the joint.As the downhole equivalent impact torque increases,the relative offset at the shoulder of internal and external threads increases.The calculation results reveal that there exists significant downhole impact torque in Well SDTK1 with complex loading environment.It is necessary to use double shoulder collar joints to improve the impact torque resistance of the joint or optimize the operating parameters to reduce the downhole impact torque,and effectively prevent drilling tool failure.

基于嵌入式的通信电源控制器软件升级系统设计

研究了一种用于通信电源控制器的软件升级系统。系统基于GD32F405RG芯片开发,在APP阶段使用RS485通信总线作为信息传输方式接收升级程序,再利用CRC等校验算法验证信息传输的正确性,接着将升级程序存储到片外存储芯片W25Q128JVSQ并重启通信电源控制器;在BootLoader阶段将升级程序搬运到GD32F405RG的内部FLASH,同样验证通过后跳转运行。文中详细介绍了系统的总体设计和具体实现方法。测试结果表明,系统在15分钟内成功完成了对通信电源控制器的软件升级,升级后通信电源控制器正常运行。这种软件升级方法降低了升级通信电源维护过程的经济投入,提高了通信电源的可持续性和稳定性。

基于RT-Thread的嵌入式网络通信系统的设计与实现

结合应用广泛的以太网物理接口和TCP/IP网络通信协议,设计了一个基于ARM Cortex-M3的嵌入式网络通信系统;系统选用源代码开放的RT-Thread操作系统,配合其中的LwIP协议栈,最终实现与远程网络设备间的数据通信。通过网络应用及测试表明,该系统能满足实时性和多任务的要求,并保证数据传输速率与可靠性。

实时操作系统RT Thread启动流程剖析

RT Thread是一个物联网实时操作系统(RTOS),它提供了线程调度、时钟管理、内存管理、线程同步与通信、中断管理等基本功能要素,具有组件完整丰富、高度可伸缩、简易开发、超低功耗、高安全性等特点。在深入分析RT Thread的功能要素和函数调用关系基础上,简要给出了其在STM32单片机芯片上的启动流程,重点剖析了RT Thread的芯片上电、板级初始化、定时器初始化、调度器初始化、线程创建、线程切换等流程,可作为RT Thread在不同微控制器上移植的技术基础,也可作为分析其他RTOS启动过程的技术参考。

面向ARM Cortex⁃M系列MCU的RT⁃Thread驻留方法

为了提高实时操作系统下应用程序的简捷性和可移植性并缩短编译时间,文中以RT⁃Thread为例,研究实时操作系统在通用嵌入式计算机架构下的驻留问题,提出BIOS与User程序的功能分离机制以及FLASH、RAM空间划分原则,并设计一种RT⁃Thread系统服务接口的映射方法,以ARM Cortex⁃M系列的STM32L431微控制器为蓝本,实现RT⁃Thread的驻留与User程序的编译。实验结果表明,将RT⁃Thread驻留于BIOS中的方法有效地实现了实时操作系统与User程序的物理隔离,缩短了微控制器应用开发的编译时间,降低了编程难度,可为RT⁃Thread的应用开发提供一种高效途径。

Nonlinear Analysis of Axial-load and Stress Distribution for Threaded Connection

Analytical method for the distributions of axial-load and stress is based on elastic assumption, but the threaded connections are often in plastic deformation stage in practice. Meanwhile the strain in the threaded connection is difficult to measure. So it is necessary to study the reliable numerical method. At present neither the convergence analysis of the computational results nor the elastic-plastic analysis in the loading-unloading process are studied. In this paper, von Mises plasticity and kinematic hardening model is used to describe the material response. A new convergence criterion for nonlinear finite element analysis of the loading-unloading process is proposed. An axisymmetric finite element model according to the proposed convergence criterion is developed and used to analyze the distributions of axial-load and stress. It can be conclude that the stress distribution analysis is more dependent on the mesh density than the axial-load distribution analysis. The stress distribution result indicates that with increasing of applied load, the engaged threads close to the nut-bearing surface become plastic firstly. The axial-load distribution result reveals that the load percentage carried by single thread depends on the position of thread and load intensity. When the load is relatively small, the applied load is mainly carried by the engaged threads near the nut-bearing surface, when the load is larger, the differences of percentages for all threads become small. The proposed convergence analyzing procedure is applicable for other nonlinear analyses. The obtained distributions of axial-load and stress can be a reference of engineering application.

采用Scheduled Thread Pool Executor执行定时重试任务时内存溢出的分析及解决

开发Java Web项目中发现服务之间的调用存在超时情况,由于涉及的处理逻辑全部是异步,引入定时重试的机制,重试工具选择了JDK自带的Scheduled Thread Pool Executor。当A服务依赖B服务,B服务由于在业务高峰期处理能力降低,导致大量A服务过来的请求超时,A加入了超时重试机制,间隔时间根据重试次数的多少来决定,次数越多,两次重试之间间隔的时间越多,此时的业务高峰也会给A带来大量请求,大量的超时会导致重试队列迅速堆积,直到内存溢出。该文从线程池工作机制、Scheduled Thread Pool Executor实例的创建,获取重试任务的过程以及提交任务的过程角度分析,并通过源代码的剖析和测试工具My Eclipse进行演示测试内存泄露的情况,得出避免内存泄露的解决方案。

Three-dimensional Finite Element Analysis of the Mechanical Properties of Helical Thread Connection

Conventional analytical and numerical methods for the mechanical properties of helical threads are relied on many assumptions and approximations and thus hardly yield satisfied results. A parameterized 3D finite element model of bolted joints with real helical thread geometry is established and meshed with refined hexahedral elements. The Von Mises plasticity criterion, kinematic hardening rule of materials and interfacial contacts are employed to make it possible for the suggested model be able to approach real assembly conditions. Then, the mechanical properties of bolted joints with different thread pitches, thread numbers and modular ratios are investigated, including the contact pressure distribution at joint interfaces, the axial load distribution and stress concentration in screw threads during the loading and unloading process. Simulation results indicate that the load distribution in screw threads produced by the suggested model agrees well the results from CHEN’s photoelastic tests. In addition, an interesting phenomenon is found that tightening the bolt with a large preload first and then adjusting the clamping force by unloading can make the load distribution more uniform and reduce the maximum residual equivalent stress in thread roots by up to 40%. This research provides a simple and practical approach to constructing the 3D finite element model and predicting the mechanical properties of helical thread connection.

基于RT Thread的可信启动实现方法

基于国产操作系统RT Thread与国产开发板AB32VG1提出一种可信启动实现方法。可信启动框架从建立可信实体与完整性度量方向出发,将U boot分割为两部分,与操作系统核心文件共同构成可信实体,发送至可信加密模块进行完整性度量,度量成功则返回控制信号至外部设备,并保存可信实体到非易失性存储器中;反之,则禁止启动,可信加密模块作为系统可信根,通过SM4与SM3双重加密完成。在AB32VG1开发板上进行验证,可正确输出控制信号,系统稳定运行、安全启动、多次加密结果正确、可快速完成完整性度量,与预期设计目标一致。

RT-Thread操作系统在STM32中移植的研究

介绍了RT-Thread操作系统在STM32F107VC上的移植,简要说明了具体的移植过程和使用的方法,并分析了RT-Thread操作系统内核代码的各个功能,给出了移植环境的如何搭建,及编写应用程序如何修改代码的方法。最后通过一个实例成功实现RT-Thread在STM32F107VC上的移植,证明了移植是可行的。