“Peel cutting” – A new cutting method for difficult-to-cut workpieces with hard oxide surfaces

A new cutting method named “peel cutting” is proposed in this research to suppress notch wear in machining of metals with hard oxide surfaces. In general, metals are produced by hot deformation processes like rolling, forging, and extrusion, which cause hard oxide surfaces called scales on their surfaces. These hard scales need to be removed first in machining of precision parts. However, the machining causes the severe notch wear at the depth-of-cut position, where the tool contacts the hard scale. To solve this problem, the proposed peel cutting avoids this direct contact between the tool and the scale by inclining the end cutting edge at an extremely large inclination (oblique) angle. This extremely oblique cutting changes the material flow and generates a “burr-like chip”. In the proposed cutting method, the tool contacts only soft non-oxide metal under the scale during cutting. Cutting of titanium alloy Ti–6Al–4V is conducted by modifying commercial tools to provide extremely large inclination angles, and it is clarified that an inclination angle of 70 deg or greater is required to realize the proposed cutting. Tool wear in the proposed cutting of the alloy with a hard scale is also observed in comparison with the ordinary cutting, and the result verifies that the notch wear can be suppressed successfully by the proposed peel cutting.     

Nucleation‐controlled dual semicrystalline morphology of polyamide 11

Crystallization of polyamide 11 at low supercooling of the melt proceeds via heterogeneous nucleation and spherulitic growth of lamellae, while at temperatures close to the glass transition homogeneous nucleation prevails, preventing spherulite formation and leading to formation of a large number of nanometer‐sized mesophase domains. It is shown that spherulitic and non‐spherulitic crystallization at low and high supercooling of the melt, respectively, can be enforced by tailoring the cooling conditions, causing a twofold semicrystalline morphology at ambient temperature. Analysis of non‐isothermal crystallization as a function of the cooling rate, using fast scanning chip calorimetry, reveals that in the case of polyamide 11 such twofold semicrystalline morphology is predicted when cooling at rates between about 20 and 200 K s^?1, since then two separate crystallization events are observed. The prediction has been confirmed by preparation of films crystallized during ballistic cooling at different rates which then were analyzed regarding their structure using optical microscopy, X‐ray diffraction and calorimetry. The study is completed by discussion of implications of twofold non‐isothermal crystallization for structure evolution in polymer processing, as well as by providing information that such behavior is not only typical for polyamide 11 but also for isotactic polypropylene or poly(butylene terephthalate) as two further examples. © 2018 Society of Chemical Industry     

智能温度测量系统设计

以AT89C52单片机作为微控制器，设计了一个智能温度测量系统。该系统通过DS18B20温度传感器实现环境温度的采集和A/D转换，模数转化后的电信号送入AT89C52单片机，再通过单片机将其送入LCD1602数码管进行显示。通过实验结果可以看出，相比较传统的温度采集方法，该系统能够快速准确地检测温度，并且检测精度可以达到0.1 ；同时，该系统具有过温点设定值调节及温度上下限蜂鸣提示的优点。     

基于STM32的开环霍尔电流传感器的温度补偿研究

研究了一种基于软件补偿结合恒流源补偿的改进温度补偿方法,应用单片机、恒流源、数字温度传感器、乘法器等硬件电路,对传统软件补偿进行了优化,补偿效果较传统恒流源补偿有了明显提升,“温漂”整体下降了约13.7%。在传统的温度补偿方法如热敏元件补偿、恒流源补偿、软件补偿等方式上做了补充,对于霍尔电流传感器精度的提升及实际生产需求的满足有重要意义。     

Loop-mediated isothermal amplification-based microfluidic chip for pathogen detection

Abstract

Due to the significant growth of food production, the potential likelihood of food contamination is increasing. Foodborne illness caused by bacterial pathogens has considerably increased over the past decades, while at the same time, the species of harmful microorganisms also varied. Conventional bacterial culturing methods have been unable to satisfy the growing requirement for food safety inspections and food quality assurance. Therefore, rapid and simple detection methods are urgently needed. The loop-mediated isothermal amplification (LAMP) technology is a highly promising approach for the rapid and sensitive detection of pathogens, which allows nucleic acid amplification under isothermal conditions. The integration of the LAMP assay onto a microfluidic chip is highly compatible with point-of-care or resource-limited settings, as it offers the capability to perform experiments in combination with high screening efficiency. Here, we provide an overview of recent advances in LAMP-based microfluidic chip technology for detecting pathogens, based on real-time or endpoint determination mechanisms. We also discuss the promoting aspects of using the LAMP technique in a microfluidic platform, to supply a guideline for further molecular diagnosis and genetic analysis.     

基因芯片法在食源性疾病中诊断效果及影响多因素Logistic分析研究

目的对比基因芯片法在食源性疾病诊断中的效果,并对影响多因素进行logistic分析。方法选择180例临床表现符合食源性疾病诊断标准的患者作为研究对象,随机均分为实验组和对照组各90例,对照组采用传统的常规培养检测方法,实验组采用基因芯片法进行检测,对比2种方法的检出率、检测耗时以及检测灵敏度。结果实验组的检出率和检测灵敏度均高于对照组的检出率和检测灵敏度,对照组的检测耗时大约是实验组检测耗时的8.24倍。结论相比常规方法,应用基因芯片法的诊断速度更快、准确率更高,在诊断食源性疾病中的应用效果更佳。通过对单因素的χ~2和t检验,确定对食源性疾病有直接影响的多个因素。对影响食源性疾病的多个因素进行Logistic分析,分析结果表明在本次研究分析中,影响较大的因素是人们的饮食卫生以及进食规律。     

用于嵌入系统的超声电机驱动设计

为了在嵌入式控制系统中充分利用超声电机特有功能,对超声电机的驱动原理进行了研究,在分析了超声电机的驱动控制原理的基础上,提出了一种基于单片机控制超声电机的软硬件控制实现方法。利用单片机输出数字量作为控制信号,通过串行输入并行输出芯片扩展后,输出到超声电机驱动器,实现超声电机启动/停止/正反转的功能;通过扩展单片机数模转换,将单片机控制超声电机速度的数字信号转换为电压信号,实现超声电机的速度控制功能;利用运行脉冲宽度控制实现超声电机的位置控制功能,并将光电编码器实现超声电机的反馈,最后通过试验验证了单片机系统实现超声电机驱动设计。     

响应面法优化甘薯脆片干燥工艺

为探究甘薯脆片热泵干燥最佳工艺,在单因素试验基础上,以烘干温度、烘干时间、切片厚度、汽漂时间为影响因素,以含油率及感官评分为响应值,用Box-Behnken试验设计建立响应面分析模型。结果表明,甘薯脆片烘干最佳工艺为:烘干温度74℃、切片厚度2.7 mm、汽漂时间3 min,烘干时间为3.5 h,在此优化条件下,甘薯脆片油炸后感官评分为88.75分,含油率为7.84%,在此条件下得到的产品色香味俱全。     

Suppression of forced vibration due to chip segmentation in ultrasonic elliptical vibration cutting of titanium alloy Ti–6Al–4V

Ultrasonic elliptical vibration cutting of titanium alloy Ti–6Al–4V is investigated in this research. Because products made of Ti–6Al–4V alloy are usually designed for possessing low-rigidity structures or good-quality cut surfaces, machining requirements such as low cutting forces and slow rate of tool wear need to be fulfilled for realization of their precision machining. Therefore, the ultrasonic elliptical vibration cutting is applied as a novel machining method for those products. Machinability of Ti–6Al–4V alloy by the ultrasonic elliptical vibration cutting with cemented carbide tools is examined to figure out suitable cutting conditions for precision machining of Ti–6Al–4V alloy. As experimental results, generated chips, cutting forces, and profiles of cut surfaces are indicated. A forced vibration problem occurred due to the segmented chip formation, which is also well-known in the ordinary non-vibration cutting. Therefore, characteristics of the forced vibration due to the chip segmentation are investigated in this research. Through the experiments, it is found that the frequency and magnitude of the forced vibration have relation with the average uncut chip thickness and cutting width. Especially, it is found that the averaging effect can suppress the forced vibration, i.e. the chip segmentation tends to occur randomly over the large cutting width, and hence the force fluctuations with random phases tend to cancel each other as the cutting width increases relatively against the average uncut chip thickness. Based on the investigations, a new practical strategy to suppress the forced vibration due to chip segmentation is proposed and verified. Using the proposed method significantly decreased cutting forces and good quality of surfaces are obtained when the forced vibration is suppressed compared to the ordinary non-vibration cutting results. Therefore, the results suggest that the precision machining can be realized without sacrificing the machining efficiency by increasing the width of cut and decreasing the average uncut chip thickness.     

一种新型高杆灯灯盘挂接装置模型的设计与实验研究

高杆灯是由钢制柱型灯杆和大功率组合式灯架构成的新型照明装置。文中对高杆灯顶部灯盘的挂接进行研究,设计了一套挂接和脱卸方便,电极对接可靠的灯盘挂接装置模型,以指导实际产品的设计制作。通过改变挂接方式与挂接装置结构,借助SolidWorks软件进行三维模型结构设计,加工装配得到挂接装置实物模型。整套机构模型利用单片机控制,引导灯盘挂接顺利完成。