利用近红外光谱分析技术快速检测乌珠穆沁羊肉中不同氨基酸含量。选取42只相同饲喂条件、体质量相近的6月龄乌珠穆沁羊,采集背最长肌、臂三头肌、股二头肌3个部位共126块肌肉样本,采集样本近红外光谱并测定氨基酸含量。采用偏最小二乘...利用近红外光谱分析技术快速检测乌珠穆沁羊肉中不同氨基酸含量。选取42只相同饲喂条件、体质量相近的6月龄乌珠穆沁羊,采集背最长肌、臂三头肌、股二头肌3个部位共126块肌肉样本,采集样本近红外光谱并测定氨基酸含量。采用偏最小二乘法关联光谱与氨基酸数据,建立乌珠穆沁羊肉中17种氨基酸的定量预测模型,最后以模型交叉验证均方根及校正决定系数(R2校正)、验证决定系数(R2验证)、预测模型的验证集标准偏差与预测标准偏差比值(ratio of standard deviation of the validation set to standard error of prediction,RPD)作为评价模型的参数。结果表明:所建立的氨基酸含量预测模型准确度较高,其中总氨基酸(total amino acid,TTA)、必需氨基酸(essential amino acid,EAA)、组氨酸、赖氨酸含量的近红外光谱预测模型的R2验证分别为0.818、0.803、0.861和0.858。分别对预测模型进行外部验证,其中EAA、组氨酸、精氨酸、丝氨酸、谷氨酸、甘氨酸、赖氨酸验证结果的RPD值均超过1.74,TAA验证结果的RPD值为2.60,预测模型准确度达到应用水平,可作为一种快速、准确测定羊肉中氨基酸含量的方法。展开更多
Gable roofs with overhangs （eaves） are the common constructions of low-rise buildings on the southeastern coast of China, and they were vulnerable to typhoons from experience. The wind pressure distributions on gabl...Gable roofs with overhangs （eaves） are the common constructions of low-rise buildings on the southeastern coast of China, and they were vulnerable to typhoons from experience. The wind pressure distributions on gable roofs of low-rise buildings are investigated by a series of wind tunnel tests which consist of 99 test cases with various roof pitches, height-depth ratios and width-depth ratios. The block pressure coefficients and worst negative （block） pressure coefficients on different roof regions of low-rise buildings are proposed for the main structure and building envelope, respectively. The effects of roof pitch, height-depth ratio, and width-depth ratio on the pressure coefficients of each region are analyzed in detail. In addition, the pressure coefficients on the roofs for the main structure and building envelope are fitted according to roof pitch, height-depth ratio and width-depth ratio of the low-rise building. Meanwhile, the rationality of the fitting formulas is verified by comparing the fitting results with the codes of different countries. Lastly, the block pressure coefficients and worst negative pressure coefficients are recommended to guide the design of low-rise buildings in typhoon area and act as references for the future＇s modification of wind load codes.展开更多
Across-wind loads and effects have become increasingly important factors in the structural design of super-tall buildings and structures with increasing height. Although researchers have investigated the problem for o...Across-wind loads and effects have become increasingly important factors in the structural design of super-tall buildings and structures with increasing height. Although researchers have investigated the problem for over 30 years, the research achievements of展开更多
The area-averaged most unfavorable wind pressure coefficients(MUWPCs)on various regions of building surfaces and the influence of the side ratio and the terrain category were studied based on wind tunnel test data of ...The area-averaged most unfavorable wind pressure coefficients(MUWPCs)on various regions of building surfaces and the influence of the side ratio and the terrain category were studied based on wind tunnel test data of scale models of typical high-rise buildings with rectangular cross-sections.The negative area-averaged MUWPCs in the middle-height edge areas generally increased with an increasing D/B side ratio.The areaaveraged MUWPCs can be well fitted with a function of the average area reduced by the square of the building depth,D^(2).In addition,no unique pattern was found for the effect of the terrain category on the MUWPCs.展开更多
文摘利用近红外光谱分析技术快速检测乌珠穆沁羊肉中不同氨基酸含量。选取42只相同饲喂条件、体质量相近的6月龄乌珠穆沁羊,采集背最长肌、臂三头肌、股二头肌3个部位共126块肌肉样本,采集样本近红外光谱并测定氨基酸含量。采用偏最小二乘法关联光谱与氨基酸数据,建立乌珠穆沁羊肉中17种氨基酸的定量预测模型,最后以模型交叉验证均方根及校正决定系数(R2校正)、验证决定系数(R2验证)、预测模型的验证集标准偏差与预测标准偏差比值(ratio of standard deviation of the validation set to standard error of prediction,RPD)作为评价模型的参数。结果表明:所建立的氨基酸含量预测模型准确度较高,其中总氨基酸(total amino acid,TTA)、必需氨基酸(essential amino acid,EAA)、组氨酸、赖氨酸含量的近红外光谱预测模型的R2验证分别为0.818、0.803、0.861和0.858。分别对预测模型进行外部验证,其中EAA、组氨酸、精氨酸、丝氨酸、谷氨酸、甘氨酸、赖氨酸验证结果的RPD值均超过1.74,TAA验证结果的RPD值为2.60,预测模型准确度达到应用水平,可作为一种快速、准确测定羊肉中氨基酸含量的方法。
文摘Gable roofs with overhangs （eaves） are the common constructions of low-rise buildings on the southeastern coast of China, and they were vulnerable to typhoons from experience. The wind pressure distributions on gable roofs of low-rise buildings are investigated by a series of wind tunnel tests which consist of 99 test cases with various roof pitches, height-depth ratios and width-depth ratios. The block pressure coefficients and worst negative （block） pressure coefficients on different roof regions of low-rise buildings are proposed for the main structure and building envelope, respectively. The effects of roof pitch, height-depth ratio, and width-depth ratio on the pressure coefficients of each region are analyzed in detail. In addition, the pressure coefficients on the roofs for the main structure and building envelope are fitted according to roof pitch, height-depth ratio and width-depth ratio of the low-rise building. Meanwhile, the rationality of the fitting formulas is verified by comparing the fitting results with the codes of different countries. Lastly, the block pressure coefficients and worst negative pressure coefficients are recommended to guide the design of low-rise buildings in typhoon area and act as references for the future＇s modification of wind load codes.
文摘Across-wind loads and effects have become increasingly important factors in the structural design of super-tall buildings and structures with increasing height. Although researchers have investigated the problem for over 30 years, the research achievements of
基金This research was supported by the National Natural Science Foundation of China(Grant Nos.50878159 and 90715040).
文摘The area-averaged most unfavorable wind pressure coefficients(MUWPCs)on various regions of building surfaces and the influence of the side ratio and the terrain category were studied based on wind tunnel test data of scale models of typical high-rise buildings with rectangular cross-sections.The negative area-averaged MUWPCs in the middle-height edge areas generally increased with an increasing D/B side ratio.The areaaveraged MUWPCs can be well fitted with a function of the average area reduced by the square of the building depth,D^(2).In addition,no unique pattern was found for the effect of the terrain category on the MUWPCs.
