现浇钢筋混凝土连续箱梁桥裂缝成因分析

从荷载、温度变化、收缩、地基础变形、钢筋锈蚀、冻胀、施工材料质量、施工工艺质量等方面分析混凝土结构裂缝的成因。     

风光互补能源系统的结构与控制策略研究

在世界能源短缺的大背景下,风光互补型能源系统以其较高的可靠性和经济型,目前成为了一种被广泛认可的能源解决方案.风能和太阳能的特性,设计了一种基于远程控制终端(RTU)的风光互补能源系统.简要介绍了其基本构成,以及系统的控制策略.并通过计算机仿真对控制方案进行了验证.实验结果对今后风光互补型能源系统的设计与研究有一定指导...     

提高电动公交车经济性的营运方式与技术方案

在分析比较电动公交车两种营运方式的电费、电池折旧费后,指出目前国内正在试运行的电动公交车的营运方式并不经济。提出了电动公交车采用自动集电器的技术方案,一方面能实现大幅度延长电池寿命的“浅充浅放”的营运方式,另一方面可以省去占地较大的专用充电站,显著降低电动公交车营运项目投资额。     

5G高清摄像机在SA组网下业务异常中断机理研究

随着5G模组和小型化5G工业网关面世,支持5G网络接入的摄像机已经出现,但5G摄像机并不仅是5G模组+传统摄像机的简单组合,而是对低峰均比、极致数传、智能编码等技术的全方位升级,文章结合南京5G+MEC智慧轨道交通行业项目应用实例,对5G摄像机在接入5GSA网络并进行极致数传过程中出现的异常中断现象展开分析,给出对应解决方案,为后期5G新技术、新产品、新应用推广提供参考与借鉴。     

上海轨道交通5号线车站建筑设计特色

针对上海轨道交通5号线沿线环境以及轻轨车站的特点,介绍了该工程车站建筑的设计特色,并对设计布置做了多方面的探讨,包括车站功能完善、规模控制、设计方法、建筑造型、结合环境以及投资控制等。     

Magnetic field tuning characteristics of bimodal ultrasonic motor stator

The magnetic field tuning characteristics of an ultrasonic motor (USM) stator are discussed. The stator consists of two piezoelectric ceramic transducer (PZT) plates and one sandwiched-in Terfenol-D plate. The dimensions of the stator are carefully adjusted to specifically discuss the influence of the magnetic field on the frequency difference between the longitudinal and bending modes of the stator. The frequency difference discussed in this paper is usually small and mainly caused by uneven materials, machining errors and changes in external conditions (temperature, pre-stress or load). The longitudinal and bending modes of the stator are simultaneously excited by an external electric field to generate the elliptic motion trajectories of the driving points. A direct current (DC) magnetic field is applied to decrease the difference between the two mode frequencies of the fabricated stator. In experiments, the dependences of the two mode frequencies and their difference on DC magnetic fields are all investigated. The experimental results indicate that the difference between the longitudinal and bending mode frequencies of the PZT/Terfenol-D/PZT composite stator can be tuned by changing the intensity of the external DC magnetic field.     

Sensorimotor self-learning model based on operant conditioning for two-wheeled robot

Traditional control methods of two-wheeled robot are usually model-based and require the robot’s precise mathematic model which is hard to get. A sensorimotor self-learning model named SMM TWR is presented in this paper to handle these problems. The model consists of seven elements: the discrete learning time set, the sensory state set, the motion set, the sensorimotor mapping, the state orientation unit, the learning mechanism and the model’s entropy. The learning mechanism for SMM TWR is designed based on the theory of operant conditioning (OC), and it adjusts the sensorimotor mapping at every learning step. This helps the robot to choose motions. The leaning direction of the mechanism is decided by the state orientation unit. Simulation results show that with the sensorimotor model designed, the robot is endowed the abilities of self-learning and self-organizing, and it can learn the skills to keep itself balance through interacting with the environment.     

Approximate method for reliability assessment of complex phased mission systems

Phased-mission systems (PMSs) have wide applications in engineering practices, such as manmade satellites. Certain critical parts in the system, such as cold standby, hot standby and functional standby, are designed in redundancy architecture to achieve high reliability performance. State-space models such as Markov process have been used extensively in previous studies for reliability evaluation of PMSs with dynamic behaviors. The most popular way to deal with the dynamic behaviors is Markov process, but it is well known that Markov process is limited to exponential distribution. In practice, however, the lifetime of most machinery products can follow non-exponential distributions like the Weibull distribution which cannot be handled by the Markov process. In order to solve this kind of problem, we present a semi-Markov model combined with an approximation algorithm to analyze PMS reliability subjected to non-exponential failures. Furthermore, the accuracy of the approximation algorithm is investigated by comparing to an accurate solution, and a typical PMS (attitude and orbit control system) is analyzed to demonstrate the implementation of the method.     

Design of car battery protection device based on torsion spring

In recent years, electric vehicles are developing rapidly in automotive industry. When involved in accidents, if the batteries of electric cars break, it is likely to cause a short circuit and start a fire. Aimed at this issue, a car battery protection device based on torsion spring has been designed. The car battery protection device can deform in a particular pattern in a collision accident. Impact energy of the accident is absorbed by the deformation, which can significantly reduce impact force on the batteries. Meanwhile, based on the principle of maximum energy absorption, some crucial parameters of the device can be determined. Furthermore, an impact simulation conducted on ANSYS software shows that maximum safety factors can be obtained when the material of car battery protection device is carbon steel. The analysis of “safe space” in the car battery protection device shows that the device can prevent battery damage effectively in general circumstances, which means the reliability of the device has been verified. Therefore, when applied to electric vehicles, the car battery protection device, which can prevent secondary accidents, significantly improves the vehicle security in accidents.     

Gain and noise figure analysis of Er<Superscript>3+</Superscript>-doped YAG transparent ceramic microchip amplifier

The rate equations and the power evolution equations based on excited state absorption (ESA) and cooperative upconversion (CUC) of high concentration erbium-doped yttrium aluminum garnet (YAG) transparent ceramic waveguide amplifier are set up to analyze the effects of the pump power, active ion concentration and waveguide length on the amplifier gain and noise figure (NF). The numerical analysis predicts that with a pump power of 100mW, an active ion concentration of 1.0×10²⁶ ion/m³ and a waveguide length of 3 cm, a small-signal gain of 30 dB and an NF of 5 dB can be achieved in the micro-chip amplifier.