24位A/D转换芯片在力标准机设计中的应用

介绍了A/D转换芯片在力标准机系统中的应用。该系统采用24位A/D转换芯片AD7190实现对力传感器信号的采集。设计了该系统中A/D转换部分的硬件电路,软件部分采用输出信号设定阈值以及均值滤波的方法,有效的抑制了系统的噪声干扰。测试结果表明,该系统的A/D转换精度达到4‰,满足系统设计的要求。     

基于DSP和FPGA的视频采集实时处理系统设计

运用高性能数字信号处理器TMS320C6713及SAA7111A,设计了一个视频采集实时处理系统.该系统采用灵活可配置的FPGA芯片对视频解码芯片SAA7111A进行视频解码控制.通过对系统的性能实验,证明该系统可以完成常用算法的实时处理.     

地铁智能广播调节系统设计

以MSP430F149单片机为控制芯片,主要通过噪音检测电路和音频放大电路,寻找地铁广播的空闲时段,采集地铁车厢内的环境噪声,A/D转换后的噪音经音频放大电路放大,适当地控制地铁车厢内的广播音量,实现在地铁噪声环境下自适音量调节控制。该系统采用TPA3112D1音频放大器、LM358双运算放大器,性能良好,适应能力较强。实验结果表明,该系统实现了音量自动调节,适应环境噪声能力良好,性价比较高,应用较为广泛。     

基于FPGA电子技术的实验设备的研制

研制了一款基于现场可编程门阵列的实验设备.该设备以XCS40-PQ208C为主芯片构建了FPGA最小系统,外围电路配置了A/D接口、D/A接口、RS232通信接口、单片机接口和步进电机接口等.此外,还设计了开放性的硬件支持,通过预留FPGA接口可以实现对不同型号和不同系列FP-GA芯片的支持.     

啤酒发酵罐群温度网络测控系统

提出了一种网络智能型啤酒发酵罐群温度测控系统，该系统采用AD590L这种性价比，线性化良好的温度传感器作为测温元件，由BCD-10进制码译码器9CC4028）和多路模拟转换开关（CC4051）组成温度矩阵测控网络，通过A/D，D/A与单片机I/O相联，实现对啤酒发酵罐群各点温度巡回检测与控制，从而保证了啤酒质量。     

基于芯片测试模式的12位A/D转换器修调技术

提出一种提高12位逐次逼近(SAR)A/D转换器精度的修调技术。该技术通过在芯片测试模式下,自动校准A/D转换器内部参考电压,从而达到提高整个A/D转换器精度的目的。电路采用COMS工艺实现,并已成功流片。测试结果显示,经过修调后12位A/D转换器有效位数至少可提高到9位,有效地提高了A/D转换器转换精度。     

基于单片机的LED闪光灯电源设计

本设计采用Ti公司的MSP430F169芯片作为系统处理核心,完成了LED闪光灯电源的构建。系统主要由开关型升压电路模块、恒流源电路模块、A/D和D/A转换模块、按键控制模块以及报警提示模块组成。开关型升压电路模块采用XL6009升压芯片,通过调节滑动变阻器,改变输出电压大小;恒流源电路模块由P沟道场效应管F9530N、LM358运放以及单片机内部D/A组成,实现恒流输出;报警提示模块使用单片机内部ADC12模数转换功能,将模拟信号转换成数字信号实现报警。该电源具有连续输出和脉动输出两种模式,并具有欠压保护和过热保护功能。     

A/D转换芯片选型

在现代工业自动控制设备中,往往需要把模拟信号转换成数字信号,经过处理后,再把处理好的数字信号转换成模拟信号输出,从而去控制设备。因此,A/D、D/A和单片机的接口电路在现代工业中的应用是很广泛的。本文主要介绍在设计A/D转换器选择A/D芯片时,从成本、性能等各方面考虑,如何选择合适的A/D芯片,使设计的前向通道A/D转换系统稳定,并得到优化。     

基于C8051F020的自动称重系统设计

针对砂轮产品生产中传统的人工称重速度慢、精度低等问题,设计了碳化硅砂子自动称重系统.该系统采用C8051F020单片机实现传感器微弱信号的采集与转换,对A/D转换值进行数字平均值滤波,并对主直流电机进行PWM调速控制,实现碳化硅砂子的实时准确称重与定量输送.实验结果表明,该系统动态称重精度较高,误差为±0.1 g,可完全满足生产要求.     

基于TMS320VC5402的谐波电源设计

以DSP芯片TMS32 0VC5 4 0 2为核心处理部件 ,外围附加高速、高性能A/D ,D/A以及RAM和FPGA等部件 ,设计了一种新型谐波电源 ,软件设计参照C 面向对象的编程思想 ,采用电压、电流各控制参量分开处理、独立运算的方式 .实践表明 ,该谐波电源工作性能稳定 ,控制精度和快速响应性能均较程控电源有较大提高 .     

Reliable identification of grapevine rootstock varieties using RAPD PCR on woody samples

Since grapevine ( Vitis spp .) rootstock material is being traded increasingly as disbudded woody material a lack of distinctive morphological features on such material necessitates an alternative and reliable means of identification. Methods described here were developed for rapid and efficient extraction of DNA from woody samples rich in phenolic compounds and polysaccharides, and for subsequent identification of varieties by RAPD PCR. Using these methods, and with the application of only one selected RAPD primer, we were able to differentiate sixteen rootstock varieties, including the seven varieties most commonly used in Germany. Problems commonly encountered with reproducibility of RAPD patterns were avoided by choosing primers with a dinucleotide sequence and a high G/C content that allowed a rather high annealing temperature of 45°C. Methods described here should also be useful for other horticultural crops, especially those with woody tissues rich in phenolic compounds and polysaccharides.     

An internet compendium of analytical methods and spectroscopic information for monomers and additives used in food packaging plastics

An internet website (http://cpf.jrc.it/smt/) has been produced as a means of dissemination of methods of analysis and supporting spectroscopic information on monomers and additives used for food contact materials (principally packaging). The site which is aimed primarily at assisting food control laboratories in the European Union contains analytical information on monomers, starting substances and additives used in the manufacture of plastics materials. A searchable index is provided giving PM and CAS numbers for each of 255 substances. For each substance a data sheet gives regulatory information, chemical structures, physico-chemical information and background information on the use of the substance in particular plastics, and the food packaging applications. For monomers and starting substances (155 compounds) the infra-red and mass spectra are provided, and for additives (100 compounds); additionally proton NMR are available for about 50% of the entries. Where analytical methods have been developed for determining these substances as residual amounts in plastics or as trace amounts in food simulants these methods are also on the website. All information is provided in portable document file (PDF) format which means that high quality copies can be readily printed, using freely available Adobe Acrobat Reader software. The website will in future be maintained and up-dated by the European Commission's Joint Research Centre (JRC) as new substances are authorized for use by the European Commission (DG-ENTR formerly DGIII). Where analytical laboratories (food control or other) require reference substances these can be obtained free-ofcharge from a reference collection housed at the JRC and maintained in conjunction with this website compendium.     

Aroma characterization of various apricot varieties using headspace–solid phase microextraction combined with gas chromatography–mass spectrometry and gas chromatography–olfactometry

The characterization of the aromatic profile of several apricot cultivars with molecular tracers in order to obtain objective data concerning the aromatic quality of this fruit was undertaken using headspace–solid phase microextraction (HS–SPME). Six apricot cultivars were selected according to their organoleptic characteristics: Iranien, Orangered, Goldrich, Hargrand, Rouge du Roussillon and A4025. The aromatic intensity of these varieties measured by HS–SPME–Olfactometry were defined and classified according to the presence and the intensity of grassy, fruity and apricot like notes. In the six varieties, 23 common volatile compounds were identified by HS–SPME–GC–MS. Finally, 10 compounds, ethyl acetate, hexyl acetate, limonene, β-cyclocitral, γ-decalactone, 6-methyl-5-hepten-2-one, linalool, β-ionone, menthone and (E)-hexen-2-al were recognized by HS–SPME–GC–O as responsible of the aromatic notes involved in apricot aroma and considered as molecular tracers of apricot aromatic quality which could be utilized to discriminate apricot varieties.     

Tests of potential functional barriers for laminated multilayer food packages. Part I: Low molecular weight permeants

The advent of the functional barrier concept in food packaging has brought with it a requirement for fast tests of permeation through potential barrier materials. In such tests it would be convenient for both foodstuffs and materials below the functional barrier (sub-barrier materials) to be represented by standard simulants. By means of inverse gas chromatography, liquid paraffin spiked with appropriate permeants was considered as a potential simulant of sub-barrier materials based on polypropylene (PP) or similar polyolefins. Experiments were performed to characterize the kinetics of the permeation of low molecular weight model permeants (octene, toluene and isopropanol) from liquid paraffin, through a surrogate potential functional barrier (25 μm-thick oriented PP) into the food simulants olive oil and 3% (w/v) acetic acid. These permeation results were interpreted in terms of three permeation kinetic models regarding the solubility of a particular model permeant in the post-barrier medium (i.e. the food simulant). The results obtained justify the development and evaluation of liquid sub-barrier simulants that would allow flexible yet rigorous testing of new laminated multilayer packaging materials.     

Textural Properties of Cold-set Gels Induced from Heat-denatured Whey Protein Isolates

A 9% whey protein (WP) isolate solution at pH 7.0 was heat-denatured at 80°C for 30 min. Size-exclusion HPLC showed that native WP formed soluble aggregates after heat-treatment. Additions of CaCl2 (10–40 mM), NaCl (50–400 mM) or glucono-delta-lactone (GDL, 0.4–2.0%, w/v) or hydrolysis by a protease from Bacillus licheniformis caused gelation of the denatured solution at 45°C. Textural parameters, hardness, adhesiveness, and cohesiveness of the gels so formed changed markedly with concentration of added salts or pH by added GDL. Maximum gel hardness occurred at 200 mM NaCl or pH 4.7. Increasing CaCl2 concentration continuously increased gel hardness. Generally, GDL-induced gels were harder than salt-induced gels, and much harder than the protease-induced gel.     

Occurrence of bisphenol-F-diglycidyl ether (BFDGE) in fish canned in oil

The levels of bisphenol-F-diglycidyl ether (BFDGE) were quantified as part of a European survey on the migration of residues of epoxy resins into oil from canned fish. The contents of BFDGE in cans, lids and fish collected from all 15 Member States of the European Union and Switzerland were analysed in 382 samples. Cans and lids were separately extracted with acetonitrile. The extraction from fish was carried out with hexane followed by re-extraction with acetonitrile. The analysis was performed by reverse phase HPL C with fluorescence detection. BFDGE could be detected in 12% of the fish, 24% of the cans and 18% of the lids. Only 3% of the fish contained BFDGE in concentrations considerably above 1mg/kg. In addition to the presented data, a comparison was made with the levels of BADGE (bisphenol-A-diglycidyl ether)analysed in the same products in the context of a previous study.     

Analysis of benzo[a]pyrene in spiked fatty foods by second derivative synchronous spectrofluorimetry after microwave-assisted treatment of samples

A simple, rapid and inexpensive method has been developed for the determination of benzo[a     

The development of reference materials for paralytic shellfish poisoning toxins in lyophilized mussel. II: Certification study

This paper describes the second part of a project undertaken to develop certified mussel reference materials for paralytic shellfish poisoning toxins. In the first part two interlaboratory studies were undertaken to investigate the performance of the analytical methodology for several PSP toxins, in particular saxitoxin and decarbamoyl-saxitoxin in lyophilized mussels, and to set criteria for the acceptance of results to be applied during the certification exercise. Fifteen laboratories participated in this certification study and were asked to measure saxitoxin and decarbamoyl-saxitoxin in rehydrated lyophilized mussel material and in a saxitoxin-enriched mussel material. The participants were allowed to use a method of their choice but with an extraction procedure to be strictly followed. The study included extra experiments to verify the detection limits for both saxitoxin and decarbamoyl-saxitoxin. Most participants (13 of 15) were able to meet all the criteria set for the certification study. Results for saxitoxin.2HCl yielded a certified mass fraction of <0.07 mg/kg in the rehydrated lyophilized mussels. Results obtained for decarbamoyl-saxitoxin.2HCl yielded a certified mass fraction of 1.59+/-0.20 mg/kg. The results for saxitoxin.2HCl in enriched blank mussel yielded a certified mass fraction of 0.48 +/- 0.06 mg/kg. These certified reference materials for paralytic shellfish poisoning toxins in lyophilized mussel material are the first available for laboratories to test their method for accuracy and performance.     

Contribution of European research to risk analysis

The European Commission's, Quality of Life Research Programme, Key Action 1—Health, Food & Nutrition is mission-oriented and aims, amongst other things, at providing a healthy, safe and high-quality food supply leading to reinforced consumer confidence in the safety of European food. Its objectives also include the enhancing of the competitiveness of the European food supply. Key Action 1 is currently supporting a number of different types of European collaborative projects in the area of risk analysis. The objectives of these projects range from the development and validation of prevention strategies including the reduction of consumers risks; development and validation of new modelling approaches; harmonization of risk assessment principles, methodologies, and terminology; standardization of methods and systems used for the safety evaluation of transgenic food; providing of tools for the evaluation of human viral contamination of shellfish and quality control; new methodologies for assessing the potential of unintended effects of genetically modified (genetically modified) foods; development of a risk assessment model for Cryptosporidium parvum related to the food and water industries; to the development of a communication platform for genetically modified organism, producers, retailers, regulatory authorities and consumer groups to improve safety assessment procedures, risk management strategies and risk communication; development and validation of new methods for safety testing of transgenic food; evaluation of the safety and efficacy of iron supplementation in pregnant women; evaluation of the potential cancer-preventing activity of pro- and pre-biotic ('synbiotic') combinations in human volunteers. An overview of these projects is presented here.