Locating and identifying sound knots and dead knots on sugi by the rule-based color vision system

Knowledge of the occurrence of sound and dead knots on the surface of sugi is important for the classification and application of the material. This study examined a color vision system for detecting sound and dead knots on sugi. The system can be conceptually divided into three components: a CCD-camera scanning system, an image-segmenting module, and a rule-based defect identifying module. The results showed that the potential defect regions could be located by Otsus threshold algorithm in conjunction with t-test analysis. The accuracies of locating sound knots and dead knots were 92.6% and 97.1%, respectively. The rule-based approach was used to identify sound and dead knots and the identifying accuracies for sound knots and dead knots were 92.0% and 94.1%, respectively. The overall detection accuracy of the system was 87.6%. The results indicated that the rule-based color vision system is an efficient means of detecting sound knots and dead knots on sugi.     

噪声对人体平衡的影响

该文研究了噪声强度、噪声频率、噪声暴露时间对人体平衡的影响 .结果表明 ,噪声强度对人体动摇的左右轨迹长和动摇速度等指标具有显著影响 ,对前后轨迹长和总轨迹长指标影响效果不显著 .随着噪声强度的增加 ,动摇总轨迹长、前后轨迹长、左右轨迹长和动摇速度呈现线性增加趋势 ,从 90dB(A)开始人体动摇明显增大 .噪声频率对人体动摇的总轨迹长、左右轨迹长、动摇速度、前后轨迹长等指标具有显著影响 .但人体动摇值与噪声频率之间不存在简单的线性增加关系 .5 0 0和 10 0 0Hz条件下人体动摇较大 ,而 2 0 0 0Hz时较小 .噪声暴露时间对人体动摇的总轨迹长、左右轨迹长、前后轨迹长和动摇速度具有显著影响 ,在较短暴露时间内 (本实验为 12 0s) ,随着暴露时间的增加人体稳定性有所增加 ,说明人体平衡功能对噪声具有一个适应过程 .     

Effects of heat treatment on water-soluble extractives and color changes of merbau heartwood

Merbau is widely used for indoor finishing, outdoor constructions, and furniture. However, it has a disadvantage in some applications in that part of its extractives is water-soluble and can be readily leached out to stain adjacent materials. This study examined whether heat treatment could overcome the above-mentioned problem. Effects of the treatment temperature and time on water-soluble extractives and color changes of merbau heartwood were studied. CIELAB ΔL ^*, Δa ^*,Δb ^*, and ΔE ^* parameters and absorbance spectra were used to evaluate color change and water-soluble extractive solutions, respectively. The results show that heat treatment is an efficient technique to overcome the problem caused by water-soluble extractives of merbau heartwood. Surface color of the treated samples tends to become darker and color of the extractive solution becomes fading to transparent when the treatment temperature and time increased. The absorbance of UV light decreases in intensity and the dominant absorption peak appears around 350 nm when the treatment temperature and time increase. The optimized parameters of treatment temperature and time are 170 °C and 4 h. Modulus of rupture and modulus of elasticity of the heat treated samples under the optimized parameters decrease by 29.6 and 12.9 %, respectively, compared with those of the untreated samples.     

A wavelet analysis-based approach for damage localization in wood beams

Free vibration testing was conducted to generate the first two mode shapes for damage detection in timbers. A wavelet transform was proposed to postprocess the mode shapes for damage pattern recognition. The wavelet used here was “db3.” The different damage severities, damage locations, and number of damaged areas were simulated by removing mass from intact beams. The results showed that the chosen wavelet db3 is suitable and that the wavelet coefficients are sufficiently sensitive to identify the existence of damage and its location in cases of different damage location, severity, and number. An edge distortion effect was apparent at the two computing edges where the wavelet coefficients were abnormally high. The wavelet coefficients showed dominant spikes around the damage locations and were zero everywhere else except the two computing edges. The dominant spikes coincided well with the damage location.     

猪繁殖与呼吸综合征病毒YA株ORF5基因的克隆与序列分析

以猪繁殖与呼吸综合征病毒（PRRSV）YA株为材料，采用RT－PCR扩增其ORF5基因全长cDNA并进行序列测定和比较分析。结果YA株ORF5基因cDNA编码区长603bp，可编码200个氨基酸残基。与欧洲型代表株LV株、美洲型代表株VR－2332株在氨基酸水平上的同尖性分别为58％和90％，与国内首株分离株(CH－1a)的同源性高达95％，推测YA株属于美洲型。根据YA株ORF5基因编码的氨基酸序列，与具有代表性的12株美洲型毒株和2株欧洲型毒株绘制进化系统树，结果也显示YA株与美洲型分离毒株的遗传关系较近，而与欧洲毒株的遗传关系较远。进一步采用序列分析软件对推导的氨基酸进行比较分析，发现YA株ORF5编码的E蛋白存在5个潜在的N－糖基化位点，6个抗原位点，其糖基化位点的数目及抗原位点的分布与其它美洲毒株均存在一定程度的差异，但3个最主要的抗原表位相对保守。     

含伪狂犬病毒完整UL49基因及部分UL48基因片段的克隆与序列分析

以地高辛标记的伪狂犬病毒（PRV）Ea株UL49.5基因片段为探针，同SalI、KpnI、BamHI消化的PRV Ea株基因组DNA进行Southern杂交，确定SalI2.8kb、KpnI17.0kb、BamHI25.0kb片段中含UL49基因。将SalI2.8kb片段克隆到pUC119中，利用其中的BamHI进行亚克隆，获得重组质粒pUC2.0。测定约2.0kb片段的全序列并进行序列分析，发现该片段包含UL50基因部分编码区，UL49.5基因和UL49基因的完整编码区，并且在UL49基因下游，还存在一段约369个碱基的序列，经与人单纯疱疹病毒I型（HSV－1）、牛单纯疱疹病毒I型（BHV－1）的UL48基因进行比对，具有较高的同源性，推测为PRV UL48基因的部分编码区。     

水稻强化栽培施肥技术探讨

在水稻强化栽培(SRI)条件下,通过有机肥与无机肥不同配比试验,结果表明:构成水稻的产量,主要是来自于无机氮肥的作用,适量搭配有机氮肥能有效控制无效分蘖,提高成穗率,增强抗倒性,达到个体与群体合理协调生长。     

Damage detection of wood beams using the differences in local modal flexibility

Local damage such as knots, decay, and cracks can result in a reduction of service life due to mechanical and environmental loadings. In wood construction, it is very important to evaluate the weakest location and to detect damage at the earliest possible stage to avoid future catastrophic failure. In this study, modal testing was carried out on wood beams to generate the first two mode shapes. A novel statistical algorithm was proposed to extract the damage indicator by computing the local modal flexibility before and after damage in timbers. Different damage severities, damage locations, and damage counts were simulated by removing mass from intact beams to verify the algorithm. The results indicated that the proposed statistical algorithm is effective and suitable for the damage scenarios considered. The algorithm was reliable for detecting and locating local damage under different damage scenarios. The peak values of the damage indicators computed from the first two mode shapes were sensitive to different damage severities and locations. This approach was also reliable for detecting multiple defects.     

Automatic detection of sound knots and loose knots on sugi using gray level co-occurrence matrix parameters

• Context  

Knowledge of the occurrence of sound and loose knots on the surface of sawn sugi (Cryptomeria japonica L.f.) is important for its grading and application.     

纤维素纳米材料技术标准体系研究

回顾国内外纤维素纳米材料的研究发展历程,对近年来国际上纤维素纳米材料相关标准化工作现状进行总结,分别介绍了纤维素纳米材料分类与命名、表征手段、商品化和环境、健康与安全等方面的相关标准,包括已经完成和正在进行的标准研制工作。根据国际上纤维素纳米材料的标准工作进展,提出制定我国纤维素纳米材料标准工作的建议和设想。