一种用于便携式12导数字化心电导联线的QRS波检测方法

针对便携式12导数字化心电导联线不易识别心电信号QRS波的问题,基于信号处理,利用小波函数良好的时频局域化特性和对时变信号分析的优越性,运用小波变换的奇异点与信号变化剧烈处间的联系理论,以软件方法实现了QRS波的检测.仿真结果表明,该方法对于QRS波、特别是R波的检测,有较高的精确度.     

基于小波变换的抑制心电信号噪声方法研究

针对在采集心电信号的过程中容易产生多种多样噪声的问题,利用小波函数的多尺度多分辨分析的特性,采用小波变换分解重构的方法,选用4尺度对心电信号进行滤波处理.仿真结果表明,该方法对于50 Hz工频干扰、肌电干扰、基线漂移有较好的抑制作用,为心电信号QRS波的识别奠定了良好的基础.     

小波阈值降噪法在心电信号处理中的应用

心电信号检测作为心脏病临床诊断的关键环节,要求检测人员必须严格按照心电信号检测原则及要求,做好心电信号检测工作。然而,因心电信号在表现特征方面多具备非平稳特性、污染噪声分布范围大等特点,导致其在一定程度上对传统线性滤波器产生了限制使用影响。目前,为去除心电信号中的噪声问题,研究人员主张运用小波阈值降噪法实现对心电信号的去噪处理。针对于此,文章主要以小波阈值降噪法为研究对象,针对小波阈值降噪法在心电信号处理中的应用实践进行研究与分析。     

起绒织物心电电极的制备及其应用

Ag/AgCl凝胶电极广泛应用于可穿戴心电测量领域,但随时间推移,凝胶逐渐风干,导致其导电性能变差。针对此问题制备了可替代其作用的起绒织物心电电极。以纯涤纶起绒纱线为基底,先采用原位聚合聚苯胺,再进行化学镀银,在纱线绒毛的表面沉积银单质制得导电纱,再用导电纱手工制备起绒织物心电电极。利用扫描电子显微镜和红外光谱对纤维表面形貌和化学组成进行了表征,测试了皮肤-电极阻抗性能和心电信号及皮肤-电极阻抗随时间的变化,评价了该电极电性能的稳定性。结果表明:在纤维表面成功沉积了可还原银离子的聚苯胺薄层,且纤维表面的镀银层致密均匀;在电学性能和心电信号测试结果中,起绒织物电极的皮肤-电极阻抗在5~500 Hz频率范围内小于1MΩ·cm^2,数值为0.65MΩ·cm^2;心电信号可分辨QRS波群以及T波心电特征波,而P波显示不清;该电极与皮肤的阻抗在4 h内保持相对稳定,在一定程度上反映了该电极可应用于可穿戴心电测量设备。     

基于谱峭度Morlet小波变换法和经验模态分解的滚动轴承故障诊断研究

本研究针对轴承早期故障信号微弱不易检测的缺陷,提出了一种基于谱峭度Morlet小波变换法和经验模态分解的轴承早期故障信号检测与增强的方法.该方法把谱峭度引入到Morlet小波中,根据谱峭度变化寻找Morlet小波的最佳匹配参数,最大限度地增强故障弱信号;然后对信号进行经验模态分解,以信号相关系数大小确定重构信号的基本模态分量,对重构信号进行包络分析完成故障诊断.实验结果验证了此方法在滚动轴承早期故障诊断中的良好应用效果.     

石榴皮水提物对中华大蟾蜍心电活动的影响

目的观察石榴皮水提物对中华大蟾蜍心电活动的影响。方法腹腔分别注射1,10,100mg/mL3种不同浓度的石榴皮水提物溶液1mL,记录麻醉状态下,中华大蟾蜍给药前后II导联心电图波形的变化,观察其心率,P波、R波、S波、P-R段、S-T段、QRS波群持续时间及波幅变化。结果与给药前相比,10,100mg/mL2种浓度的石榴皮水提物均使动物心率显著变慢;随着给药时间延长心率变慢更趋明显,一直持续到给药后30min;而1mg/mL组的心率随实验时间的延长也变慢,但无显著差异。3组动物P波、R波、S波、P-R段及S-T段的持续时间和波幅变化与给药前相比均无显著差异;10mg/mL组的QRS波群时程在给药15～30min期间显著延长。结论10,100mg/mL石榴皮水提物对麻醉蟾蜍的心率和心电活动均有抑制作用;石榴皮水提物对麻醉蟾蜍心电活动的调节作用主要表现为影响心室的去极化过程,对心房去极化及复极化过程的影响均不显著。     

石榴皮水提物对中华大蟾蜍心电活动的影响

目的 观察石榴皮水提物对中华大蟾蜍心电活动的影响.方法 腹腔分别注射1,10,100 mg/mL 3种不同浓度的石榴皮水提物溶液1 mL,记录麻醉状态下,中华人蟾蜍给药前后Ⅱ导联心电图波形的变化,观察其心率,P波、R波、S波、P-R段、S-T段、QRS波群持续时间及波幅变化.结果 与给药前相比,10,100 mg/mL 2种浓度的石榴皮水提物均使动物心率显著变慢:随着给药时间延长心率变慢更趋明显,一直持续到给药后30 min;而1 mg/mL组的心率随实验时间的延长也变慢,但无显著差异.3组动物P波、R波、S波、P-R段及S-T段的持续时间和波幅变化与给药前相比均尤显著差异;10mg/mL组的QRS波群时程在给药15～30 min期间显著延长.结论 10,100 mg/mL石榴皮水提物对麻醉蟾蜍的心率和心电活动均有抑制作用;石榴皮水提物对麻醉蟾蜍心电活动的调节作用主要表现为影响心室的去极化过程,对心房去极化及复极化过程的影响均不显著.     

基于边缘检测算子的两类B样条小波的性质和作用

基于Ｍａｌｌａｔ多尺度分析理论，用边缘检测算子构造两类任意阶Ｂ样条小波。给出了这两类小波的小波函数ψ的时域及频解析表达式，讨论了相应的性质及在异常信号检测中的应用。     

基于小波包分析的超声相控阵检测信号特征提取

通过对超声相控阵A扫信号进行小波分析,研究了基于小波能谱信息熵的特征信息获取方法。并对最优小波基的选取提出了基于能量差异原则的选取方法,对40种小波基的能量差异进行分析,选取了三种小波基对两类A扫信号进行小波包分析,用于信息熵值的提取。最后对掺杂不同杂质的碳纤维复合材料的A扫信号的超声检测信号应用所选小波基进行分解,计算了信息熵值并加以比对,作为不同掺杂下碳纤维复合材料的超声相控阵信号的特征值。     

基于小波分析的航空发动机气动失稳信号分析方法

文章旨在做好航空发动机气动失稳信号的有效分析,通过应用小波变换的方式分析了小波变换的原理,以航空发动机气动失稳信号检测为例分析了小波变换过程的信号失稳检测,信号分析结果表明借助于小波变换的时频分析能力逐渐增强,故障诊断率高,应用价值较好。     

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.     

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.     

低温带皮菜籽粕微粉的不同粒级部分的功能特性

为研究低温带皮菜籽粕微粉的不同粒级部分的功能特性,以经低温脱脂的带皮菜籽粕为原料,经微粉碎后筛分成212~425μm、150~212μm和106~150μm的3个不同粒级的微粉样品,检测这些样品的吸水性、吸油性、乳化性和乳化稳定性、蛋白质体外消化率。结果表明:1 3个不同粒级的微粉样品之间的粗纤维含量存在显著差异,表明三者的结构组成成分有一定差异。23个微粉样品的乳化活性和乳化稳定性随粒度级别的减小而显著增加(P0.01)。33个微粉样品的蛋白质体外消化率随粒度级别的减小而显著增加(P0.01)。4不同粒级带皮菜籽粕微粉样品的吸水性与吸油性受其结构组成物质不同和粒度的双重影响,与粒度的相关性不明显。     

Microbiology of food taints

Fresh and processed foods are often spoilt by the presence of undesirable flavours and odours caused by microbial action. The aim of this paper is to review the current knowledge of microbiologically induced taints that occur in a wide range of foodstuffs, including meats, poultry, fish, crustaceans, milk, dairy products, fruits, vegetables, cereals and cereal products. Examples have been chosen where the compounds responsible for the taint have been identified and sufficient data obtained to demonstrate the involvement of microorganisms. However, in some cases the full identity of the causative organism may not have been elucidated. The types of microorganisms covered by this review include bacteria, fungi, yeasts, actinomycetes and cyanobacteria. Although cyanobacteria do not in general infect foods, their presence in aqueous systems and water supplies can lead to off-flavours in aquatic organisms and processed foodstuffs. Several examples of each of these processes are discussed. Wherever possible, the likely biosynthetic pathway used by the microorganism to produce the offending compound in a foodstuff is indicated.     

Analysis for organic residues from aids to polymerization used to make plastics intended for food contact

Polymers intended for food contact use have been analysed for organic residues which could be attributed to a range of substances employed as polymerization aids (e.g. initiators and catalysts). A wide range of polymers was extracted with solvents and the extracts analysed by gas chromatography-mass spectrometry (GC-MS). The overwhelming majority of substances identified were not derived from aids to polymerization but were oligomers, additives and adventitious contaminants. However, a small number of substances were identified as initiator residues. These included tetramethylsuccinonitrile (TMSN) which was observed in two polymers and it derived from recombination of two azobisisobutyronitrile (AIBN) initiator radicals. Methyl benzoate, benzoic acid, biphenyl and phenyl benzoate were detected in one poly(methyl methacrylate) sample and in two polyvinylchlorides and they are thought to be derived from benzoyl peroxide initiator. TMSN was subsequently targeted for analysis of poly-(methyl methacrylate) plastics using proton nuclear magnetic resonance spectrometry (¹     

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

Experiments were performed to characterize the kinetics of the permeation of different medium molecular weight model permeants: bisphenol A, warfarin and anthracene, from liquid paraffin, through a surrogate potential functional barrier (25 microns-thick orientated polypropylene--OPP) into the food simulants olive oil and 3% (w/v) acetic acid. The characterization of permeation kinetics generally observed the permeation models previously reported to explain the experimental permeation results obtained for a low molecular weight group of model permeants. In general, the model permeants exhibited behaviour consistent with their relative molecular weights with respect to (a) the time taken to attain steady-state permeation into the food simulant in which they were more soluble, (b) their subsequent steady-state permeation rates, and (c) their partition between liquid paraffin and the OPP membrane.     

The development of reference materials for paralytic shellfish poisoning toxins in lyophilized mussel. I: Interlaboratory studies of methods of analysis

This paper describes the first part of a project undertaken to develop mussel reference materials for Paralytic Shellfish Poisoning (PSP) toxins. Two interlaboratory studies were undertaken to investigate the performance of the analytical methodology for several PSP toxins, in particular saxitoxin (STX) and decarbamoyl-saxitoxin (dc-STX) in lyophilized mussels, and to set criteria for the acceptance of results to be applied during the second part of the project: the certification exercise. In the first study, 18 laboratories were asked to measure STX and dc-STX in rehydrated lyophilized mussel material and to identify as many other PSP toxins as possible with a method of their choice. In the second interlaboratory study, 15 laboratories were additionally asked to determine quantitatively STX and dc-STX in rehydrated lyophilized mussel and in a saxitoxin-enriched mussel material. The first study revealed that three out of four postcolumn derivatization methods and one pre-column derivatization method sufficed in principle to determine STX and dc-STX. Most participants (13 of 18) obtained acceptable calibration curves and recoveries. Saxitoxin was hardly detected in the rehydrated lyophilized mussels and results obtained for dc-STX yielded a CV of 58% at a mass fraction of 1.86 mg/kg. Most participants (14 out of 18) identified gonyautoxin-5 (GTX-5) in a hydrolysed extract provided. The first study led to provisional criteria for linearity, recovery and separation. The second study revealed that 6 out of 15 laboratories were able to meet these criteria. Results obtained for dc-STX yielded a CV of 19% at a mass fraction of 3.49mg/kg. Results obtained for STX in the saxitoxin-enriched material yielded a CV of 19% at a mass fraction of 0.34mg/kg. Saxitoxin could not be detected in the PSP-positive material. Hydrolysis was useful to confirm the identity of GTX5 and provided indicative information about C1 and C2 toxins in the PSP-positive material. The methods used in the second interlaboratory study showed sufficiently consistent analysis results to undertake a certification exercise to assign certified values for STX and dc-STX in lyophilized mussel.     

Focus on China's Paper Industry

In the English section of this issue, 〈China Paper Newsletters〉 will introduce ＂National Development and Reform Commission Issued Announcement for Selection of Major Preliminary Research Projects for the ＇13th Five-Year Plan＇＂, ＂2013 Annual Report of China＇s Paper Industry＂, and news of projects and other policies.     

Listen to downstream & search for innovation

正Nowadays,textile enterprises are all taking efforts in transformation and upgrading,like improving producing capacity and optimizing production structure to face market downturn.It claimed a higher request to the standard of textile equipments.In the upcoming of ITMA ASIA+CITME 2014exhibition,this magazine have interviewed several branch associations and a series of relative enterprises,to summarize industrial developing status