RESEARCH ON MICROWAVE HUMIDITY TESTING OF CERAMIC PRODUCTS

This paper analyses the principle of microwave humidity testing. According to the problems in the production procedure of ceramic products, a microwave humidity testing system is designed and analyzed for its advantages. Furthermore, the system has been applied to the production line that produces ceramic products and the testing results are also satisfying.

Effect of microwave-vacuum drying(MVD)method on quality properties of agro-products

Microwave-vacuum drying is an accepted drying method for agro-products, which is nonetheless still relatively unknown to some. This paper attempted to give an overview of the most important aspects of microwaves-vacuum drying （MVD） and their relevance to agro-products processing. Some advantages on microwave-vacuum drying properties were discussed to provide a better insight into the reasons for the use of microwaves. Also the effects of the MVD on the quality of several agro-products and reasonable processing parameters were given, which develop the guidance to the application of MVD on the agro-products dehydration. As a potential drying technology, MVD will be broadly utilized for the other agro-products processing

STUDY ON MICROWAVE DIELECTRIC PROPERTIES OF EPOXY RESIN MIXTURES USED FOR RAPID PRODUCT DEVELOPMENT

This paper presents a preliminary study on the dielectric properties and curing of three different types of epoxy resins mixed at various stoichiometric mixture of hardener, flydust and aluminium powder under microwave energy. In this work, the curing process of thin layers of epoxy resins using microwave radiation was investigated as an alternative technique that can' be implemented to develop a new rapid product development technique. In this study it was observed that the curing time and temperature were a function of the percentage of hardener and fillers presence in the epoxy resins. Initially dielectric properties of epoxy resins with hardener were measured which was directly correlated to the curing process in order to understand the properties of cured specimen. Tensile tests were conducted on the three different types of epoxy resins with hardener and fillers. Modifying dielectric properties of the mixtures a significant decrease in curing time was observed. In order to study the microstructural changes of cured specimen the morphology of the fracture surface was carried out by using scanning electron microscopy.

Switchable down-,up-and dual-chirped microwave waveform generation with improved time–bandwidth product based on polarization modulation and phase encoding

A switchable down-,up-and dual-chirped microwave waveform generation technique with improved time–bandwidth product(TBWP)is proposed and demonstrated based on a dual-polarization dual-parallel Mach–Zehnder modulator(DPDPMZM)cascaded with a polarization modulator(Pol M).By properly controlling the phase shifts of the radio frequency signals applied to the DP-DPMZM,switchable down-,up-and dual-chirped waveforms with simultaneous frequency and bandwidth doubling can be generated.To enlarge the TBWP further,splitting parabolic signal and phase-encoding splitting parabolic signal are used to drive the Pol M for the enhancement of bandwidth and time duration.Numerical results demonstrate the generation of down-,up-and dual-chirped microwave waveform with TBWP of 8,160 and 10240.The proposed method may find applications in future multifunction radar systems due to the high performance and flexibility.

The Effects of Microwave Pretreatment of Dairy Manure on Methane Production

This study was undertaken to evaluate the efficiency of a liquid-solids separation process and microwave pretreatment, as well as anaerobic biodegradability of microwave pretreated dairy manure. Liquid-solids separation of raw dairy manure resulted in solid and liquid fractions having different properties, with the solid fractions richer in total and volatile solids content and liquid fractions richer in nutrients and metal ions. Substantial amounts of soluble chemical oxygen demand and nutrients were released into the solution after the microwave treatment. The microwave pretreated dairy manure was also subjected to anaerobic digestion. The kinetic parameters of methane production potential, maximum methane production rate and lag time were determined using the modified Gompertz equation. Anaerobic digestion of liquid manure, without microwave treatment, outperformed the sets with microwave treatment. The microwave-treated liquid dairy manure, without acid addition had better results in terms of methane potential and methane production, than with acid addition. Thermophilic digestion exhibited a higher maximum methane production rate than that of mesophilic digestion, but lower methane yields. The microwave pretreatment of dairy manure resulted in high soluble chemical oxygen demand;however, methane yield was not increased.

Low temperature microwave-assisted vs conventional pyrolysis of various biomass feedstocks

A comparison between conventional pyrolysis and a novel developed low-temperature microwave-assisted pyrolysis methodology has been performed for the valorisation of a range of biomass feedstocks including waste residues. Microwave pyrolysis was found to efficiently deliver comparable evolution of bio-gases in the system as compared with conventional pyrolysis at significantly reduced temperatures （120-180 ℃vs 250-400 ℃）. The gas obtained from microwave-assisted pyrolysis was found to contain CO2, CH4 and CO as major components as well

Preparation of lithium carbonate by microwave assisted pyrolysis

Investigations were conducted to purify crude Li_(2)CO_(3)via direct carbonation with CO_(2)at atmospheric pressure and pyrolysis with both water bath heating method and microwave heating method.The reaction kinetics of LiHCO_(3)pyrolysis was studied and the effect of different operating conditions including initial concentration of LiHCO_(3)solution,pyrolysis temperature and stirring speed on the purity of Li_(2)CO_(3)was investigated to obtain the optimal operating conditions.Results showed that the effect law is similar in the two pyrolysis processes.The purity of the Li_(2)CO_(3)increases firstly and then decreases with the increase of the initial concentration of LiHCO_(3)solution and the stirring speed,while the purity of Li_(2)CO_(3)first decreases and then increases with the increase of pyrolysis temperature.The product yield increases with the increase of initial concentration of LiHCO_(3)solution and pyrolysis temperature and is essentially unaffected by the stirring speed.Under the optimal operating conditions,the purity of Li_(2)CO_(3)can reach up to 99.86%and 99.81%in water bath heating and microwave heating process,respectively.In addition,the pyrolysis rate of microwave assisted pyrolysis is 6 times that of water bath heating process,indicating that the microwave heating technology can significantly improve pyrolysis efficiency and reduce energy consumption.

微波技术在食品和农产品加工中应用研究进展

微波加热技术具有速度快、可控性高等特点,在食品和农产品的热加工过程中具有较强的应用潜力。该文在分析微波加热原理的基础上,从技术应用、设备研制和仿真研究等方面介绍微波加热应用现状,如在农产品干燥、杀菌、萃取和膨化等方面进行深入研究和应用。指出微波加热在机理解析、工艺局限性、加热不均匀性和能量利用低等问题,尤其是微波场对物料内极性成分作用机制的研究深度、微波加热时在物料内温度和水分分布的不均匀性规律定量表征等方面,严重影响产品质量稳定性和能量充分利用。从揭示微波在加热腔体内传递和物料内吸收的机理,提高微波加热均匀性和改善加工质量,以及研制智能化工业用微波加工设备等方面,指出微波加热技术在食品和农产品加工中应用热点研究方向。针对微波加热技术在农产品和食品加工中科学问题、技术需求和设备现状,为发挥技术优势、拓展应用领域,该文提出微波加热理论研究与技术应用的发展趋势,以期提高微波热加工技术工业化应用适用性、保证产品质量和能量利用率。

铁磁性颗粒辅助微波加热分解南海神狐海域天然气水合物实验研究

南海北部陆坡神狐海域是中国天然气水合物首次试采区,90%以上的水合物储存在泥质粉砂地层中。为实现天然气水合物的高效开发,必须提高泥质粉砂中天然气水合物的平均产气速率和能量效率比。笔者以泥质粉砂作为水合物合成基底,对合成的甲烷水合物开展了微波加热分解实验,研究了加入不同种类铁磁性颗粒对甲烷水合物分解的影响规律。试验结果表明,在平均产气速率和能量效率比方面,加入铁钴合金粉末的实验组表现最佳,相较空白组提高22.66%。加入纳米钡铁氧体颗粒对反应前期分解效率具有显著促进作用,纳米颗粒的小粒径和大比表面积有助于其均匀分布,优化了润湿性和表面张力,降低了“贾敏效应”。经Avrami模型分析表明,铁磁性颗粒对微波分解水合物具有良好的促进作用,其中纳米钡铁氧体效果最显著。

微波防治烟草粉螟效果及经济阈值研究

为研究微波辐照对烟草粉螟的杀虫作用,评估微波防治烟草粉螟的应用价值及经济阈值,使用自制微波设备,设置不同的功率和时间对烟草粉螟的卵、幼虫和蛹进行处理。结果表明,当微波功率和处理时间为4 kW、220 s,5 kW、190 s和6 kW、170 s时,均能100%杀灭烟草粉螟卵、各龄幼虫和蛹。不同幼虫密度下,烟草粉螟幼虫对烟叶造成的间接经济损失均远大于直接经济损失。单头烟草粉螟幼虫期对烟叶的经济损失率为0.40%,微波防治烟草粉螟的经济阈值为2.95头/kg。因此,当虫口密度>2.95头/kg时,采用微波防治烟草粉螟具有实际生产意义,最适杀虫微波功率和处理时间为6 kW、170 s。

微波辅助热解废旧塑料的研究进展

微波加热是基于电磁场与物质间的相互作用,利用它可实现对废塑料的高价值回收利用。对比了常规加热和微波加热对废塑料热解产物的影响,综述了微波应用于不同塑料热解、塑料与生物质共热解的研究进展,特别是所生产的油、气和焦炭的产量,最后讨论了利用微波辅助热解技术处理废塑料的挑战和前景。

蓝莓花色苷对美拉德有害产物形成的抑制作用

目的探究微波加热处理对美拉德有害产物积累情况的影响以及蓝莓花色苷对模拟体系中美拉德有害产物形成的抑制效果。方法本研究通过构建牛血清蛋白-葡萄糖模拟体系,对其进行不同时间微波加热处理,以类黑精、晚期糖化终末产物、乙二醛、羧甲基赖氨酸、丙烯酰胺含量为指标,探讨样液中相关美拉德有害产物与加热时间的关系以及不同浓度的蓝莓花色苷溶液对美拉德有害产物的抑制效果。结果随着微波加热时间增加,美拉德有害产物不断积累。在微波加热180 min的条件下,不同浓度的蓝莓花色苷均表现出明显的抑制美拉德有害产物生成的能力,并且0.030mg/mL的蓝莓花色苷溶液对大部分物质抑制效果最好。结论蓝莓花色苷在食品热加工过程中,对美拉德有害物质生成有抑制作用,对未来食品安全和生物健康都具有重要意义。

微波处理和干制时间对干鲍体外模拟消化产物抗氧化活性的影响

本实验以鲍鱼肌肉为研究对象,干燥过程中定期(0、30、60、90、120 d)利用微波处理,并利用模拟消化制备干鲍鱼肌肉消化产物(abalone muscle digestion products,AMDP),通过测定AMDP的体外及体内抗氧化活性指标,考察微波处理和干制时间对鲍鱼肌肉体外模拟消化物抗氧化活性的影响。结果表明,干制0 d的未经微波处理的AMDP对·OH、N,N-二甲基对苯二胺二盐酸盐自由基和1,1-二苯基-2-三硝基苯肼自由基的半清除率(half maximal inhibitory concentration,IC50)分别为3.04、15.18 mg/mL和21.12 mg/mL。随着鲍鱼肌肉干制时间的延长,AMDP对上述3种自由基的IC50逐渐下降。利用干制120d制备的AMDP饲喂秀丽隐杆线虫(Caenorhabditis elegans),与对照组相比,其身体长度从768.90μm增加至1034.62μm、头部摆动频率从206次/min提高至281次/min,在正常条件下平均寿命延长了36.16%,而在热应激和氧化应激条件下平均寿命分别延长了59.41%和38.48%。延长鲍鱼肌肉干制时间可以提升AMDP饲喂线虫体内的抗氧化酶活力、还原型谷胱甘肽含量和总抗氧化能力,降低线虫体内的活性氧含量。综上,延长干制时间以及干燥过程中利用微波处理鲍鱼肌肉均可以提高AMDP的抗氧化能力。

国内外7种常用南极被动微波海冰密集度产品的比较与评估

围绕国内外机构发布的南极被动微波海冰密集度产品(PM-SIC)的差异和精度问题,应用MODIS和Sentinel-1反演的海冰密集度,对德国不莱梅大学(产品UB-AMSR2/ASI)、美国冰雪数据中心(产品NSIDC-SSMIS/NT、NSIDC-SSMIS/CDR、NSIDC-AMSR2/NT2)、欧洲气象卫星应用组织海洋与海冰卫星应用中心(产品OSI-SAF/BR-BST)、国家卫星海洋应用中心(产品NSOAS-SMR/NT)和国家卫星气象中心(产品NSMC-MWRI/NT2)发布的7种南极海冰密集度产品进行比较与评估。结果表明:(1)NSIDC-SSMIS/NT与NSIDC-SSMIS/CDR海冰密集度具有较高的一致性(平均偏差为-0.08%,相关系数为0.99),NSOAS-SMR/NT与NSIDC-AMSR2/NT2间的差异最大(平均偏差为-14.41%,相关系数为0.81);(2)7种PM-SIC的变化趋势一致,NSOAS-SMR/NT和NSMC-MWRI/NT2与其他PM-SIC的偏差具有明显的季节性差异;(3)NSOAS-SMR/NT和NSMC-MWRI/NT2与其他PM-SIC均在印度洋扇区、别林斯高晋海和阿蒙森海扇区绝对偏差较大,在罗斯海扇区差异最小。偏差较大的区域主要分布在海冰边缘区及近陆地海域,在高密集度区域差异较小;(4)应用MODIS与Sentinel-1反演的海冰密集度对7种PM-SIC验证表明,NSMC-MWRI/NT2与验证数据的一致性最高。NSOAS-SMR/NT、UB-AMSR2/ASI和OSI-SAF/BR-BST海冰密集度偏低,而NSMC-MWRI/NT2、NSIDC-AMSR2/NT2、NSIDC-SSMIS/CDR和NSIDC-SSMIS/NT海冰密集度偏高。不同海冰密集度产品的比较与评估可为发展遥感反演算法、研制和应用高质量的海冰密集度产品,更好地监测南极海冰动态变化提供依据和参考。

冷冻干燥联合微波干燥对枇杷花茶品质的影响

为研究冷冻干燥联合微波干燥对枇杷花茶品质的影响,采用真空冷冻干燥(VFD)、微波干燥(MVD)和真空冷冻联合微波干燥(VFMVD)对枇杷花进行干燥,测定不同干燥工艺下枇杷花茶的复水比、总黄酮含量、总三萜含量和感官品质。结果表明:采用VFMVD干燥的产品,其复水比高于MVD,低于VFD;VFMVD干燥后总黄酮、总三萜含量高于MVD,低于VFD,但感官评价得分高于VFD。该研究表明,VFMVD是一种有效结合MVD和VFD优点的干燥技术,在枇杷花干燥上具有较好的应用前景。

响应面法优化微波膨化鱼糜制品料坯配方的研究

以冷冻鱼糜为主要原料,通过单因素实验,考察淀粉种类、淀粉添加量、食盐添加量、膨松剂添加量、蛋清粉添加量对微波膨化鱼糜制品料坯的凝胶强度、膨化度、质构特性、感官评分的影响;采用Plackett-Burman试验筛选确定影响料坯品质的关键因素,通过Box-Behnken试验设计和响应面方差分析优化了微波膨化鱼糜制品料坯的最佳配方。结果显示,最适合添加到微波膨化鱼糜制品料坯中的淀粉种类是糯米淀粉,食盐添加量、糯米粉添加量和复配膨松剂添加量是影响料坯品质的主要影响因素。微波膨化鱼糜制品料坯的最佳配方为:以鱼糜质量为基准,食盐添加量2.16%、糯米粉添加量6.26%、复配膨松剂添加量0.49%、蛋清粉添加量0.9%,在此条件下料坯的凝胶强度为16729.33±270.72 g·mm,感官评分为85.8±0.84,与预测值无显著性差异(P>0.05)。研究为新型鱼糜制品的开发提供了参考依据。

药用胶塞常用抗氧剂及可提取硫含量测定方法

目的 建立一种高效液相色谱法,以同时检测药用胶塞中多种抗氧剂和可提取硫。方法 采用二氯甲烷作为提取溶剂,微波萃取药用胶塞中的目标化合物,用高效液相色谱法测定目标物的含量。色谱柱为Waters Symmetry RP 18,流动相为乙腈甲醇水,梯度洗脱,检测波长为277 nm。结果 该方法能高效地分离目标化合物,各化合物分离度良好。在0.2~20μg/mL内线性良好,相关系数r≥0.999 3,检测限为0.03~0.09μg/mL,回收率为86.73%~108.91%,相对标准偏差RSD为0.47%~5.68%。通过该种方法测定不同厂家不同批次药用胶塞,结果检出了抗氧剂BHT及其降解物BHT–CHO、BHT–Q,抗氧剂1076和1010及其降解物1310,以及可提取硫。结论 文中建立的高效液相方法准确、简便、灵敏度较高,能够高效快速地测定药用胶塞中常用抗氧剂及其降解产物与可提取硫的含量。

微波消解-电感耦合等离子体发射光谱法测定面制食品中总铝含量

目的 建立面制食品中总铝的微波消解-电感耦合等离子体发射光谱(inductively coupled plasma atomic emission spectrometry, ICP-AES)的测定方法。方法 优化雾化气和等离子气流量、HNO3浓度等实验参数,HNO3-H2O2、HNO3-HF-H2O2、HNO3-HF-H2O2-HClO4等3个样品消解体系,选取最优的微波消解程序,来用ICP-AES方法测定总铝含量。采用铝标准溶液系列绘制标准曲线,确定方法的线性方程和检出限;对5份生物成分标准物质和5份市售面制食品样品进行6次平行检测和加标试验,评估方法的精密度和准确度。结果 优选雾化气和等离子气流量分别为0.60 L/min和13.0 L/min, HNO3浓度为2.0%,采用HNO3-HF-H2O2-HClO4消解体系进行样品消解处理后,进行ICP-AES检测。该方法在0~7.0 mg/L质量浓度范围内线性良好(r=0.999 9),检出限为0.6 mg/kg,相对标准偏差(RSD)0.76%~5.19%,加标回收率90.6%~108.0%。4份生物成分标准物质中铝测定值均在标准值允许范围内,5份市售面制食品样品平均测定值7.8~81.2 mg/kg。结论 建立的HNO3-HF-H2O2-HClO4微波消解-电感耦合等离子体发射光谱法测定面制食品中总铝含量灵敏度高、准确性好、分析速度快,可用于面制食品中总铝含量的测定。

籽瓜固形物微波真空干燥特性及其品质研究

以甘肃白银“籽瓜1号”为试验材料,利用微波真空干燥对籽瓜综合加工利用副产品籽瓜固形物进行干燥试验,探究干燥温度、真空度和比功率对干制品干燥特性和理化品质的影响。结果表明,随着干燥温度与真空度增大,比功率减少,物料水分比的下降速率增加,干燥效率提高。籽瓜固形物的有效水分扩散系数在0.70074×10^(-9)~4.56579×10^(-9)m^(2)/s之间,并随干燥温度、真空度和比功率的升高而增大。干燥温度50℃、真空度-0.070 MPa、比功率20 W/g时,样品中多糖(105.44 mg/g)、VC(1.21 mg/g)和膳食纤维(80.69%)含量最高,且复水比较高(4.23),色泽明亮。综合来看,微波真空干燥可较好地保证籽瓜固形物的综合品质,提高产品的附加值。本研究可为籽瓜固形物潜在价值的挖掘和产业化加工提供理论参考。

催化组分加强秸秆裂解制氢的研究

生物质制氢作为一种绿色、清洁、零排放的技术,目前已经引起越来越多人的关注。该技术具有长期发展的潜力,有望逐步减少环境污染和资源浪费。本实验采用微波裂解技术从不同原料、微波功率、催化组分预处理秸秆等方面对产物进行研究,重点关注了对裂解气产率及氢气含量的影响。结果表明,从裂解气产率上看,在600 W条件下,KOH、Na_(2)CO_(3)的催化效果最明显,气体产物产率由不加催化剂预处理的49%分别增加到58.4%、56.2%,NaOH催化剂条件下的裂解气产率比无催化剂条件下略低。从气体组分含量看,三种催化组分均可提高H_(2)含量并抑制CH_(4)的生成。其中高粱秸秆经KOH预处理效果最好,氢气含量由28.67%提升到32.19%.