基于卓越工程师教育的频率特性分析课堂教学研究

频率特性分析在工程应用中具有重要的作用,在电路分析、模拟电子技术、信号与系统、自动控制理论等相关课程中都涉及到相关章节内容,在不同课程中如何根据工程应用和学生学习阶段把握具体的讲解内容和讲解方式非常重要。本文从频率特性的求解方法和具体物理意义角度开展在不同课程中讲解的方法,从时域和频域角度分别讨论其物理意义和具体的分析方法。通过渐进深化的教学过程和教学方法不断提高学生的知识掌握和应用技能,提高学生的工程意识、工程素质和工程创新能力,强化学生对于频率特性课程知识的综合应用能力。     

小型核桃脱壳分选一体机的设计

核桃不仅营养价值极高,而且核桃壳的药用价值也非常高,国内小企业和家庭在核桃硬壳脱壳加工环节,一般采用人工破壳取仁的方式,这种方式劳动强度大,人工成本高且不卫生;针对这个问题设计了一款小型的硬壳脱壳,壳仁分离分选的机器来提高生产效率,减少成本,提高收入。     

Vulnerable objects detection for autonomous driving: A review

Object detection performed by Autonomous Vehicles (AV)s is a crucial operation that comes ahead of various autonomous driving tasks, such as object tracking, trajectories estimation, and collision avoidance. Dynamic road elements (pedestrians, cyclists, vehicles) impose a greater challenge due to their continuously changing location and behaviour. This paper presents a comprehensive review of the state-of-the-art object detection technologies focusing on both the sensory systems and algorithms used. It begins with a brief introduction on the autonomous driving operations and challenges. Then, different sensory systems employed on existing AVs are elaborated while illustrating their advantages, limitations and applications. Also, sensory systems employed by different research are reviewed. Moreover, due to the significant role Deep Neural Networks (DNN)s are playing in object detection tasks, different DNN-based networks are also highlighted. Afterwards, previous research on dynamic objects detection performed by AVs are reviewed in tabular forms. Finally, a conclusion summarizes the outcomes of the review and suggests future work towards the development of vehicles with higher automation levels.     

Technology enhanced learning of quantitative critical thinking

A Quantitative Critical Thinking (QCT) software tool was developed in this study to facilitate students’ learning of quantitative critical thinking via repeated practice by chemical engineering students reading a core module called fluid-solid systems. The software tool generated detailed calculation steps to typical engineering design problems encountered in this module that contained weaknesses, flaws or even errors. Students utilized the software tool to practice identifying these weaknesses, flaws or errors in the design solutions and then present a better or correct design by applying the concepts and knowledge acquired in the module. Since the QCT software tool was built upon an existing design software tool that was able to generate the correct, detailed design calculation steps to design problems, students were able to check their own design calculations against those presented by the software tool during this second learning step, thereby engaging in and learning quantitative critical thinking via a repeated practice approach. The software tool was successful in enhancing the performance of second-year undergraduate students in solving a question that required quantitative critical thinking in the final examination of the module. The average percentage scores achieved by students for the question who reported higher frequencies of usage of the software were generally higher than those who reported lower frequencies of usage or did not utilize the software tool throughout the semester.     

Nonstoichiometric effect of A-site complex ions on structural,dielectric, ferroelectric,and electrostrain properties of bismuth sodium titanate ceramics

To investigate the nonstoichiometric effect of (Bi_0.5Na_0.5)TiO₃ (BNT) ceramics on their properties, we propose a novel chemical expression, (Bi_0.5+xNa_0.5−3x)TiO₃. The nonstoichiometric effect of BNT can be explored in compounds with this composition without being hampered by the charge imbalance problem. With x ranging from −0.02 to 0.02, we find that the morphological, dielectric, ferroelectric, and electrostrain properties differ considerably between Na-rich and Bi-rich ceramic samples. The average grain size (AGS) increased significantly in Na-rich samples compared to that in stoichiometric BNT, while it decreased slightly in Bi-rich samples. The dielectric characteristics measured from 30 °C to 500 °C indicate that conductivity is activated in Na-rich nonstoichiometric samples but is effectively suppressed in Bi-rich nonstoichiometric samples. The ferroelectric properties also show the same trend. In Na-rich samples, elliptical polarization against electric field (P-E) hysteresis loops were detected, indicating a conductive character induced by high electric field loading. However, saturated P-E loops are observed in Bi-rich samples with well-inhibited conductivity. Furthermore, compared to stoichiometric BNT and nonstoichiometric x = 0.02 Bi-rich samples, (Bi_0.5+xNa_0.5−3x)TiO₃ samples with x = 0.01 exhibit higher electrostrain from 30 °C to 150 °C. Based on the assumption of charge balance, our findings indicated that the presence of 1 mol% excess Bi would facilitate significant improvement in the dielectric, ferroelectric, and electrostrain properties of BNT and BNT-based systems.     

Simulation is essential for embedded control systems with task jitter

Sampling or task jitter affects the performance of digital control systems but realistic simulation of this effect has not been possible to date. Our previous work has developed a novel method to simulate sampling jitter in MATLAB/Simulink simulation software where the jitter is generated randomly. What has been missing is a way to capture sampling jitter from a target platform and then feed this timing information into the simulation. This paper presents a low-cost and novel solution to these problems. The method uses an Arduino board to capture task jitter from two different hardware platforms with multiple stressing conditions. Then the recorded performance data is used to drive realistic simulations of a control system. Measurement shows that the task jitter data does not follow any specific random distribution such as Gaussian or Uniform. Furthermore, very occasional timing patterns, which may not be picked up while testing a real system, can result in extreme controller responses. This novel method allows comparisons of different platforms and reduces the effort required to choose the most appropriate platform for full implementation.

     

机械设备故障规律及运行趋势预测方法综述

对于机械设备的故障运行问题,技术人员应当深入研究机械设备的故障规律,并研究出运行趋势的预测方法,从传感器的检测时间间隔与使用数量等方面加以深入的研究。本文介绍了机械设备运行状态的故障预测方法,并将机械设备运行状态的故障预测方法总结为三个步骤,分别是数据获取、处理与设备寿命预测,结合这些内容,提出了关于机械设备故障运行的一些方法,旨在为相关技术人员提供参考依据。     

Inter-Sample and Intra-Sample Variability in Electronic Properties of Methylammonium Lead Iodide

While the challenges associated with the stability of metal halide perovskites are well known and intensely studied, variability in electronic properties represents an equally significant, yet seldom studied, challenge that could potentially slow or inhibit the commercial viability of these systems. In this work, the contactless characterization technique time-resolved microwave conductivity (TRMC) is used to quantify the variability in electronic properties of the prototypical perovskite, methylammonium lead iodide (MAPbI₃) both between different samples, and at different locations within the same sample. Using scanning electron microscopy (SEM) and a quasi-automated image-analysis strategy, it is possible to evaluate the metrics of heterogeneity in surface microstructure and correlate them with the electronic properties as obtained by TRMC. Substantial intra-sample and inter-sample variation is observed in the mobility-yield product in samples prepared following differing protocols, and in samples prepared following identical protocols.     

Application of web embedded system and machine learning in english corpus vocabulary recognition

Built-in applications built on a stand-alone device, TCP / IP network and interconnected are a need for high integration with other systems. The system provided through Web services interconnects service-oriented distributed architecture. The TCP / IP network is widely employed to integrate business applications. This integration is still not provided through the embedded application. The applications connected to the Internet are an especially difficult problem in embedded systems to interpret the sensor data. Real-time sensor function generates a training/classification result for IoT application selected, customized, or data structure design. It has an integrated hardware/software system to achieve the continuous training and real-time data analysis and re-training of Machine Learning (ML) algorithm. World of English native speakers on top of all, this is the database of words that have been separated from the local and non-collection English. It also reported a variety of methods that are used in the English vocabulary recognition system. Please check the study of learners of mediation based on the part of the corpus. Students, in writing, too much-advanced technology and general vocabulary. These students, publicly their discourse in and contributed to the professional corpus of "existence" I mentioned that there is a professional writer, is better. To stimulate the different means of integration, it evaluated several network technology today, discussing the balance between the use of shared with this integration in the adaptability and built-in the field of Web network technology of today.     

Down-link OFDRMA communications

Wireless Networks - Orthogonal frequency-division multiplexing with random multiple access (OFDRMA) is discussed for down-link communications, whereby a single base-station transmits information...