基于超声波回波分析的单板层积材质量检测系统

系统提出一种以超声波回波分析理论建立检测模型的方法,以单板层积材为研究对象,通过超声波换能器探头对其质量进行无损检测,并对超声波回波进行时域及频域实验分析和讨论.分析了FFT变换后的频谱图,通过对比频谱图可判断出单板层积材的质量,实现在线检测.     

利用超声无损检测对木质材料的特性研究

使用超声换能器,利用一发一收2个超能换能器对射式检测方式,对橡木指接板、中密度纤维板、细木工板、刨花板4种木质材料的频谱和声速进行了分析研究。研究表明在500 kHz的超声波时,均会产生"频移"现象,并且频移程度按以上顺序依次增加,细木工板和刨花板的"频移"现象尤其剧烈,500 kHz的超声波成分基本已经消失。结合超声波信号比较,能清晰地区分4种木质材料。     

基于超声波的自动清洗机设计

设计了一款自动化程度高、清洗效果好、节能环保的用于清洗绘画用调色盘的清洗机。实验表明,该超声波清洗机清洗效果好,能有效地清洗调色盘上的颜料。     

关于草坪打孔机与对草坪生长的影响

文章通过选取内蒙古牙克石市区草坪实验地的综合对比实验,采取了对不同实验样地进行打孔或不打孔的实验方法,通过两年多的实地观测和研究,获得了对草坪生长非常有价值的重要的生长参数,提出了对牙克石市区草坪的最佳打孔季节,对种植草坪的单位和个人有重要的参考价值。     

应用新型高效打孔注药技术防治松材线虫病初报

打孔注干技术是保护松树免受松材线虫病侵害的重要方式,然而目前打孔药剂剂型的选择十分单一,缺乏针对松树研发的载药体系,并且在长效防护和病情控制方面表现不佳.本文介绍应用两种新型打孔注干药剂,对松材线虫病严重发生区的松树进行预防保护和发病进程控制,防效显著.所用药剂为新型长效固体颗粒剂和新型速效打孔纳米乳剂,两种药剂均使用...     

栗实象鼻虫无公害防治药剂筛选实验

药剂筛选实验结果表明:无公害农药对栗实象鼻虫的防治作用因药剂种类及施药浓度不同而异。其中,用齐螨素、吡虫啉等5倍液,树干打孔注药效果最佳。     

三种方法对双条杉天牛防治效果研究

为筛选出防治效果最好的方法,该研究采用树干喷药、打孔注药、树体输液3种方法对双条杉天牛进行防治试验.结果表明,3种方法防治效果排序为树干喷药(钻无忧)>打孔注药(10％吡虫啉)>树体输液(输活+高狂).树干喷施法(钻无忧)效果最好,校正防治效果为90.24％;树干基部打孔注药法(10％吡虫啉)次之,校正防治效果为82....     

沼肥对设施葡萄理化性质及品质的影响

采用单因素完全随机区组设计,在3座条件相对一致的红地球葡萄日光温室内,共设定了15种不同的施肥措施,进行了实验对比,结果显示设施葡萄施用沼肥可显著增加产量,提高品质。单一沼液、单一沼渣、混合沼液+沼渣处理相比,混合沼液+沼渣效果较好;不同处理次数间相比,以混合沼肥8渣+16液的效果最好。     

五原县光肩星天牛综合治理技术

上世纪九十年代初，光肩星天牛在巴彦淖尔市发生危害，并成为该地区主要害虫，防治措施由单一砍伐除治向高干截头、萌芽更新、打孔注药防治天牛成虫、营造多树种混交林等方式转变，形成了打孔注药防治天牛成虫、结合布设人工鸟巢招引啄木鸟等生物防控综合治理技术。     

仿生木材结构穿孔纤维板吸声性能

以中密度纤维板为基材,通过设计穿孔结构及打孔方式,达到拓宽木质穿孔板吸声频带和提高声学性能的目的.利用分层加工工艺制备了带侧孔结构的穿孔纤维板,采用阻抗管传递函数法对穿孔纤维板吸声性能进行了测试.通过正交试验方法,研究了主孔直径、穿孔率、倾斜角度对穿孔纤维板吸声性能的影响,并获得了较优的制备工艺,随后利用控制变量法研究...     

Effect of coupling media on velocity and attenuation of ultrasonic waves in Brazilian wood

Coupling media are necessary to ensure that transducers bond to wood specimens to minimize coupling losses and improve the accuracy of ultrasonic measurements. There are several types of coupling media available, and the optimal choice is not known. In this work, we analyzed the results of ultrasonic wave attenuation for 0.1-MHz longitudinal and transverse transducers with six different materials as coupling media in nine species of Brazilian wood with densities in the range 700–1170 kg/m³. Tests were performed using constant pressure on the transducer and with wave propagation in the longitudinal direction. For transverse transducers, the polarization was in the radial and tangential directions. The results were analyzed statistically and showed that, for attenuation in both longitudinal and transverse waves, the material used for coupling had significant effects, whereas the wood species had no effect. For longitudinal waves, the statistical evaluation showed that the coupling material performance was strongly dependent on the species of wood, but it was not possible to observe any tendency of behavior associated with specific anatomical properties.     

Feasibility of ultrasonic spectral analysis for detecting insect damage in wooden cultural heritage

In cultural heritage, insect damage is one of the most serious damages, but conventional ultrasonic methods could not detect the early stage of insect damage because it is too small. In order to detect such small size damages, the analysis of attenuation is required, but elastomeric couplant and inconsistent contact condition of transducer make it difficult, in which only the elastomeric couplant is allowed to be applied to cultural heritage because of the paintings on the surface and the pressure employing transducers make effects on the attenuation measurement. Therefore, this study was aimed to investigate if the ultrasonic spectrum analysis can detect internal small hole, in which ultrasonic test was conducted with varied contact pressure. In this study, the diameter of drill hole was only 3 mm and this experiment was carried out under severely varied contact pressure. Nevertheless, spectral analysis with 2nd derivative pretreatment (Root mean square error of prediction, RMSE: 1.609) predicted the number of holes with much higher accuracy than the conventional methods (RMSE: 5.925). This result indicates that the spectral analysis has a high possibility in detection of insect damage in cultural heritage, even though contact condition is not consistent.     

Variation of stress wave velocity with MC and temperature

 The effect of moisture content (MC) and temperature on the stress wave velocity and signal frequency spectrum through sapwood has been investigated. It was discovered that in 2.5 m long green boards only low frequencies were present in the transmitted signal, while for boards less than 500 mm long, the much higher resonance frequency of the transducer was dominant. For green boards between 0.5 and 2.5 m both low and high frequency components were present. The frequency spectrum was monitored for a 540 mm long board over a range of moisture contents and temperatures. When the MC was below 30% the transmitted signal waveform consisted almost entirely of the transducer resonance frequency, while at higher moisture contents, low frequency components predominated. The frequency spectrum of the transmitted signal was little affected by temperature, but it was affected by the type of transducers used. The effect of temperature and moisture content on stress wave velocity was studied and is displayed in the form of a three dimensional graph. Received 3 May 1999     

响应面法优化蓝靛果抗氧化成分提取的工艺研究

在液料比、超声波作用时间、提取温度、超声波功率和乙醇体积分数5个单因素试验基础上,利用响应面分析法,以二苯基苦基肼自由基(DPPH.)清除率为评价指标,对超声波提取蓝靛果中抗氧化成分的工艺条件进行了优化。结果表明,最佳提取条件为:蓝靛果鲜果2.5 g,液料比26∶1(mL∶g),提取温度52℃,超声波功率160 W,乙醇体积分数53%。此优化条件下,DPPH.清除率为67.13%。     

超声辅助提取对竹纤维结构和机械性能的影响

文章以超声波辅助提取竹纤维,研究超声波处理以及超声波处理方式（前超声和后超声）对低试剂量条件下提取竹纤维结构和热性能的影响。结果表明：超声波处理应用于低试剂量竹纤维提取,可降低竹纤维胶质含量,改善竹纤维细度和细度均匀性。用后超声辅助提取竹纤维,竹纤维胶质含量可降低13.2%,纤维直径由489±247 μm降至224±52 μm,平均直径降低率达54.2%。超声辅助提取对竹纤维机械性能有一定程度的影响,对竹纤维拉伸强度略有降低,拉伸模量下降明显,断裂伸长率略有提高,机械强度均匀性增加;后超声辅助提取较前超声辅助提取对竹纤维的机械性能降低程度小。经提取工艺,竹纤维结晶度增加,但超声辅助提取竹纤维结晶度又略有下降,未超声竹纤维结晶度为56.50%,后超声竹纤维结晶度为55.89%,前超声竹纤维结晶度为56.25%;傅里叶红外光谱分析表明,竹纤维化学结构变化主要由纤维提取工艺引起,超声处理对纤维结构影响不明显;通过电镜观察,经纤维提取工艺,原竹材结构中被胶质包覆的单纤维形态暴露,单丝状明显,超声辅助提取增加了纤维表面粗糙度,后超声辅助提取单丝分散性增强;总体上,超声辅助提取可促进低试剂量条件下的长竹纤维提取,对纤维细度有明显改善效果,但对纤维结构和机械性能影响不大。     

林业机械超声检测新技术的探讨

本文研究超声波及换能器扫描的方法对林业机械进行检测，把超声回波的振幅，相位的空间分布和时间记录下来，输入到计算机，用计算机进行数据处理，把检测到机械上的损伤和缺陷在显示器上显示出来，达到预报林业机械故障的目的。     

Grading of construction timeber by ultrasound

Summary The resistance of spruce beams was characterized with the aid of nondestructive ultrasonic measurements. The modulus of elasticity and the modulus of rupture in flexure for beams of commercial sized section can be estimated by observing the speed of propagation of a longitudinal wave applied to the longitudinal axis of the beam. The use of simple ultrasonic equipment and two experimental transducers (in direct and dry contact) permit measurements to be performed in industry. The technique constitutes the basis of an objective concept for classification of sawn timber guaranteeing a better reliability and profitability with regard to the visual grading rules used in Western Europe. This research was supported by The National Research Fund     

基于Sentinel-2影像的火烧迹地快速提取方法比较研究

利用Sentinel卫星数据,特别是其中对植被敏感的红边波段与短红外波段,针对提取灾后火烧迹地研究不足的问题,选取四川省冕宁县4月20日森林火灾发生前后的Sentinel-2卫星数据,使用不同的提取方法探究识别火烧迹地的潜力,并进行对比研究。实验结果表明,决策树分类法识别火烧迹地的能力最好,提取精度最高,BAI指数次之;其余方法均受道路、房屋和裸体不同程度的影响;用红边波段替换可见光红波段的效果相比原有指数提取效果并无明显提升。研究证明在各类方法中,采用决策树分类法能快速高精度地将火烧迹地准确提取出来。     

超声波木材缺陷检测若干问题的探讨

根据超声波木材缺陷检测中的实践经验，主要针对探头的直径、频率以及耦合剂的使用方法对木材超声检测做了一定分析、研究和总结。结果表明，缩小超声探头直径和选用适当频率的超声探头可提高对缺陷检测的准确性，使用橡胶垫做耦合剂在木材检测中能取得良好效果。