基于GPRS网络的农村电网监测系统设计

设计了一种基于GPRS网络的农村电网监测系统.该系统利用STC12C5410AD单片机片内定时器测量频率和相位差,与采样、放大、精密整流和滤波电路配合,通过瞬时采样法测量电压、电流有效值,并把正常运行信息和故障信息通过GPRS无线通信模块传送给数据中心.该系统具有体积小、价格低、功耗低、方便实用、稳定可靠等特点,是电网参数远程监测的一个有效的解决方案.     

可变增益控制放大器设计与研究

本文描述的可变增益放大器由AT89S51单片机、可变增益放大电路、控制电路、比较器等组成。可通过选择按钮开关选择或调整放大器的增益,也可通过采样电路将采样信号与理想输出信号进行比较,通过AT89S51单片机程序调整放大器的增益,实现自动增益的控制。     

基于CCD的片烟规格测量装置的设计应用

现使用的打叶后烟叶面积的测量方法是人工采样、筛选分级、称重,以及计算每个面积段的片烟比例。该检测方法为离线检测模式,其测定结果滞后,无法及时指导生产。为此,设计了基于CCD(Charge-coupled device)图像传感器的片烟规格测量装置,通过测量片烟的面积比反映打叶效果。该装置由工作平台、弹簧板、电磁铁和衔铁组成片烟分散装置;光源置于镜头正下方,与工作平台构成图像采集部分。在单片机的控制下,CCD图像传感器与片烟分散装置协调工作,每个周期采集一帧数据,采用二值化电路将视频信号转换为二进制数据,并完成片烟面积计算和比例统计工作。与传统的称重测量法相比,该装置能够及时、准确、自动测量片烟的面积并统计各个面积段的片烟比例,为打叶工序工艺参数的快速调整提供了依据。     

基于电能芯片CS460的远距离电能测试仪研究

文章介绍了以CS5460为核心的电能测试仪,该测试仪采用AT89C52单片机为中央处理器,通过对电路的电流和电压测量,实现了对电能的测量。通过显示屏显示测得的数据并由无线传输模块将数据输出给PC机处理。     

验证理想气体状态方程实验装置的设计

文章设计一种验证理想气体状态方程的实验装置.该实验装置为一体化实验仪,通过多种传感器进行参数测量,利用单片机控制低功率加热棒、半导体制冷片和活塞实现温度和体积的改变以及压强的恒定,从而验证理想气体状态方程.该装置还可以进行气体比热容测定实验.     

基于单片机的测量尺设计

本设计利用超声波指向性强,能量消耗缓慢,在介质中传播的距离较远的特点,通过单片机编程产生40kHz的方波,由P1.0口输出,再经过放大电路,驱动超声波发射探头发射超声波。发射出去的超声波经障碍物反射回来后,由超声波接收头接收到信号,通过接收电路的检波放大、积分整形及一系列处理,送至单片机,为了提高测量精度,引入温度传感器DS18B20对环境温度进行测量,单片机根据环境温度选择超声波的传播速度,然后利用声波的传播速度和发射脉冲到接收反射脉冲的时间间隔计算出障碍物的距离,并由单片机控制显示出来。     

数控直流电源设计

系统采用单片机技术与开关电源技术相结合,由升压电路、电压与电流采样电路和信号放大电路构成数字化直流电源。实现对输出电压与电流的设置,同时通过AD采样控制校正电压,从而有效的提高该电源电压及电流的输出精度。     

纸张厚度自动测量系统设计与实现

纸张厚度自动测量系统以STC15F2K61S2单片机为主控器,由NE555芯片与平行金属板构成的多谐振荡电路、信号采集电路、控制电路、存储电路、报警电路、按键控制电路、Nokia5110液晶显示等电路组成。通过对振荡电路将被测电容值的变化转化为频率值的变化关系进行分析,再通过对单片机不同频率信号进行分析处理,运用多种算法精确测出纸张的实际频率,从而根据不同频率值计算出与纸张的数量对应关系。测试系统具有频率采集、处理、计数显示和自校准功能,并将校准数据参数存储于AT24C02中。通过WiFi无线通信电路、专用手机APP程序,可实现测试的纸张张数在移动终端实时显示。该系统识别迅速、准确、适应性强,能够满足纸张厚度测试实验设计要求,为纸张测量设备智能制造提供参考。     

交流量的单片机检测系统设计

在电源系统中,常常需要对交流电源进行监测,其监测量主要为电压、电流、频率、功率因数等。本文介绍了常用单片机采样电路的硬件结构和软件算法;提出了全周期采样算法,并对测量的误差进行了分析。     

电量测量仪表的设计与实现

提出了一种三相多功能电量测量系统设计方案.该方案以凌阳单片机为处理器,利用多功能芯片ADE7758对交流信号采样和计算,可实时测量三相电压、三相电流、有功功率、无功功率、视在功率及电量等参数,具有电量、电价、历史记录存储和RS485接口的远程抄表等功能.用标准的测试设备对系统的测量精度进行了实验论证,结果表明,系统测量精度达到0.5级,可以满足一般场合电量测量的精度以及电力设备实时监控方面的要求.     

黄酒发酵过程中物位测量技术的研究与改进

对大罐黄酒发酵工艺过程中物位测量技术进行了研究,采用射频导纳技术实现在导电介质中物位测量技术的实现,分别针对前后酵发酵过程中物料的不同属性特征,进行数据模型的算法设计,并对挂料问题进行了分析与改进,以保证发酵过程中物料物位的测量精准度,提高黄酒品质。针对物位测量技术设计一套物位控制系统,对物位测量系统硬件部分的电源电路进行了设计,提出了单片机PWM输出时钟与取样积分电路两种方案,进一步提高了物位测量技术的准确率;并提出了前后酵发酵导纳数学模型,并采用visual studio 2015设计了上位机监控系统,可以在线实时查看发酵罐内的物位;采用RFID技术实现发酵罐之间、发酵罐与监控系统之间的无线通信,不仅提高了数据传输的可靠性,也填补了国内在测量黄酒发酵物位测量技术方面的空白。     

针刺式谷物含水率检测仪设计

为了提高谷物含水率在线检测的精确度和速度,更好地满足烘干机械在线检测的要求,设计了一种直接刺入谷物籽粒的对称针形含水率检测传感器;并配合高精度检测电路与优化算法,设计了相应的系统检测装置。试验结果显示,该装置对稻谷含水率的测量误差不大于1%,单次测量响应时间小于2s。通过简单的参数设定,该装置即可应用于不同种类谷物的水分检测。该检测方法的提出为谷物含水率在线测量提供了新的解决方案。     

微机控制预付费智能电表系统的研制

设计了一种基于87C51单片机的IC卡预付费电表,阐述了单相IC卡电度表的工作原理、设计方法和硬件电路并讨论了其工作过程,同时给出了程序的主要工作过程流程图和设计思想.实际应用表明,该系统计量精度高、抗干扰性好,且结构简单.     

10—THE VARIABILITY OF YIELD AND FINENESS IN SOME CARDING AND INFERIOR TOPMAKING WOOLS

Studies of sampling variability relating to the measurement of yield and fineness of greasy wool have been published previously for auction lots of Australian wool in spinners-wool categories.

This paper describes similar studies for auction lots of carding and inferior topmaking wools. As expected, the between-bales and within-bales variability proved higher for these wools than for the spinners wools. Nevertheless, present sampling practices are expected to give acceptable precision.     

Designing and utilizing 3D printed chitosan/halloysite nanotubes/tea polyphenol composites to maintain the quality of fresh blueberries

In this study, we prepared a composite of chitosan (CS), halloysite nanotubes (HNTs), and tea polyphenols (TP) using 3D printing technology. The intermolecular interactions between the components and the printability of the ink were analyzed via Fourier transform infrared (FTIR) spectroscopy and rheological properties. The prepared CS/HNTs-TP composite container exhibited high fidelity and precision. The effects of printing parameters, such as nozzle diameter, air pressure, nozzle height, printing speed, and layer height, on the precision of printed CS/HNTs-TP composite containers were examined. The optimal parameters for printing 3D constructs were found to be 0.8-mm nozzle diameter, 0.4-MPa air pressure, 0.5-mm nozzle height, 30-mm/s printing speed, and 0.3-mm layer height, matching the target model with fine resolution, smooth surface texture, and high precision. The printed CS/HNTs-TP composite container was used for storing blueberries. After 12 days of storage, the blueberries preserved in the CS/HNTs-TP composite maintained a 41.87% weight loss ratio, a 59% decay rate, 9.1% total soluble solids (TSS), 4.1 N firmness, 0.43% titratable acidity (TA), and 14.27% ascorbic acid when compared with those of the control group and CS group. The results indicate that CS/ HNTs-TP composites are highly effective in maintaining the quality of blueberries.     

Improved quantitative recovery of Listeria monocytogenes from stainless steel surfaces using a one-ply composite tissue

Four sampling devices, a sterile environmental sponge (ES), a sterile cotton-tipped swab (CS), a sterile calcium alginate fiber-tipped swab (CAS), and a one-ply composite tissue (CT), were evaluated for quantitative recovery of Listeria monocytogenes from a food-grade stainless steel surface. Sterile 304-grade stainless steel plates (6 by 6 cm) were inoculated with approximately 106 CFU/cm2 L. monocytogenes strain Scott A and dried for 1 h. The ES and CT sampling devices were rehydrated in phosphate buffer solution. After plate swabbing, ES and CT were placed in 40 ml of phosphate buffer solution, stomached for 1 min and hand massaged for 30 s. Each CS and CAS device was rehydrated in 0.1% peptone before swabbing. After swabbing, CS and CAS were vortexed in 0.1% peptone for 1 min. Samples were spiral plated on modified Oxford agar with modified Oxford agar Rodac Contact plates used to recover any remaining cells from the stainless steel surface. Potential inhibition from CT was examined in both phosphate buffer solution and in a modified disc-diffusion assay. Recovery was 2.70, 1.34, and 0.62 log greater using CT compared with ES, CS, and CAS, respectively, with these differences statistically significant (P < 0.001) for ES and CT and for CAS, CS, and CT (P < 0.05). Rodac plates were typically overgrown following ES, positive after CS and CAS, and negative after CT sampling. CT was noninhibitory in both phosphate buffer solution and the modified disc-diffusion assay. Using scanning electron microscopy, Listeria cells were observed on stainless steel plates sampled with each sampling device except CT. The CT device, which is inexpensive and easy to use, represents a major improvement over other methods in quantifying L. monocytogenes on stainless steel surfaces and is likely applicable to enrichment of environmental samples.     

Domestic cooking and food skills: A review

Domestic cooking skills (CS) and food skills (FS) encompass multiple components, yet there is a lack of consensus on their constituent parts, inter-relatedness, or measurement, leading to limited empirical support for their role in influencing dietary quality. This review assessed the measurement of CS and FS in adults (>16 years); critically examining study designs, psychometric properties of measures, theoretical basis, and associations of CS/FS with diet. Electronic databases (PsychInfo), published reports, and systematic reviews on cooking and home food preparation interventions provided 834 articles of which 26 met the inclusion criteria. Multiple CS/FS measures were identified across three study designs—qualitative, cross-sectional, and dietary interventions—conducted from 1998 to 2013. Most measures were not theory-based, limited psychometric data were available, with little consistency of items or scales used for CS/FS measurements. Some positive associations between CS/FS and fruit and vegetables intake were reported, though lasting dietary changes were uncommon. The role of psycho-social (e.g., gender, attitudes) and external factors (e.g., food availability) on CS/FS is discussed. A conceptual framework of CS/FS components is presented for future measurement facilitation, which highlights the role for CS/FS on food-related behavior and dietary quality. This will aid future dietary intervention design.     

扩散硅压力传感器在水力模型实验装置液位测控中的应用

基于扩散硅压力传感器良好线性标准输出,结合方便的校验、标定方法,通过接口电路,将扩散硅压力传感器作为压力测量元件,应用于水力模型实验装置过程控制系统.该设计不仅使测量精度得到提高,克服了量程迁移误差,而且由于它采用标准输出,易于实现多点集成化、数字化网络测量与控制.     

基于TI低功耗MSP430的便携式血糖仪设计

设计了一种基于TI低功耗MSP430单片机的便携式血糖仪.通过恒电位检测电路,获取微电流信号,采用业界功耗最低的MSP430单片机作为主控制器,完成模拟数据采集和数据处理功能.本设计具有低功耗、高效率、高精度的特点,仪器小巧,适合个人、家庭使用.     

气相色谱法测定饮料中苯甲酸的一些改进

探讨了通过改变样品处理方法，色谱条件及进样量，改进传统气相色谱法测定饮料中苯甲酸的方法。以增加峰面积，提高测量的准确度和精密度，苯甲酸测定的检出限为1mg/ml，相对标准偏差为1.30%，样品加标回收率为93％－104％。