Influence of lipid composition on physicochemical properties of nanoliposomes encapsulating natural dipeptide antioxidant l-carnosine

Natural dipeptide antioxidants (l-carnosine) are recieving increasing attention because of their noticeable potential as biopreservatives in food recent technology. Encapsulation of antioxidants by nanoliposomes could represent an ameliorative approach to overcome the problems related to the direct application of these antioxidant peptides in food.     

利用散射辐射分布矩测量表面轮廓均方根斜率

为了利用激光散射分布测量表面粗糙度参数,从分析高斯粗糙表面非傍轴散射光能量的角分布特征与轮廓均方根斜率之间的关系,得到了利用散射角分布进行粗糙表面横向粗糙度参数的测量方法。提出了散射光的两个特征值：辐射立体角密度矩M(θ)和M（φ）,用以表征散射光能量立体角分布情况,并给出了在非傍轴远场条件下的测量和计算方法。实验证明,给出的特征参数能够得到散射光能量立体角分布特征并可用于测量粗糙表面横向形貌参数。     

高斯条件下基于粒子滤波的声源定位

介绍了粒子滤波的基本思想和具体算法实现步骤,并将粒子滤波算法应用在声源定位中,解决了在高斯噪声环境下的声源定位问题。所提出的基于粒子滤波的声源定位方法,在高斯噪声情况下,甚至在低信噪比（SNR〈-20dB）情况下,定位的均方根误差RMSE值均小于0．2m。     

富兰克实验结果与理论偏差的讨论

分别以平衡态分布和理想等速观点对富兰克-赫兹实验的实验结果进行讨论，揭示了实验曲线产生偏差的原因。     

基于随机森林的高分辨率 PM2.5 遥感反演 ——以广东省为例

细颗粒物(PM2.5)监测是大气污染治理的重要手段,受限于地面观测点的数量,从遥感反演 PM2.5 是常规地面观测的有效补充,是当前的研究热点。通常遥感反演 PM2.5 的思路是先反演大气气溶胶光学厚度,然后基于统计关系由大气气溶胶光学厚度反演 PM2.5。该方法容易造成误差传递,从而 导致反演模型的不稳定。该文提出了一种基于随机森林算法(一种机器学习算法)的 PM2.5 遥感反演方法,直接建立中分辨率成像光谱仪(Moderate Resolution Imaging Spectroradiometer,MODIS)影像与地 面实测 PM2.5 的关系,可以避免传统反演 PM2.5 时先反演大气气溶胶光学厚度带来的误差,最终得到精度更高的 PM2.5 反演结果。该方法先用随机森林算法对 MODIS 影像和经过克里金插值后的地面监测站PM2.5 数据进行训练和测试;然后,根据测试的均方根误差从多个模型中选取最优(均方根误差最小)的模型;最后,将此模型用于整幅 MODIS 影像,得到整个区域的 PM2.5 反演结果。实验选取了广东省 四个季节多幅 MODIS 影像数据进行验证,并通过决定系数和均方根误差两个表现指标进行对比和分析,验证了所提算法的优越性。     

射线平均速度对反射波时距方程简化的效果分析

介绍在简化的双曲型时距曲线方程中应用射线平均速度计算多层介质地震反射波旅行时的方法与效果。地震反射波时距方程的估计精度对地震勘探记录的动校正及偏移成像质量的影响很大。本文提出利用射线平均速度计算反射波旅行时的方法,并用于多层介质中层状均匀各向同性模型和层状弱各向异性模型中计算反射波旅行时。通过对比这两种模型中用射线平均速度、均方根速度、平均速度,以及非双曲线时距方程计算的反射波旅行时与其理论值的误差,认为在炮检距较大的情况下,通过在双曲时距方程中引入射线平均速度,可以比较更精确的计算出反射波旅行时。     

A Comparison of Two Approaches to Ranking Algorithms Used to Compute Hill Slopes

The calculation of slope (downhill gradient) for a point in a digital elevation model (DEM) is a common procedure in the hydrological, environmental and remote sensing sciences. The most commonly used slope calculation algorithms employed on DEM topography data make use of a three-by-three search window or kernel centered on the grid point (grid cell) in question in order to calculate the slope at that point. A comparison of eight such slope calculation algorithms has been carried out using an artificial DEM, consisting of a smooth synthetic test surface with various amounts of added Gaussian noise. Morrison's Surface III, a trigonometrically defined surface, was used as the synthetic test surface. Residual slope grids were calculated by subtracting the slope grids produced by the algorithms on test from true/reference slope grids derived by analytic partial differentiation of the synthetic surface. The resulting residual slope grids were used to calculate root-mean-square (RMS) residual error estimates that were used to rank the slope algorithms from best (lowest value of RMS residual error) to worst (largest value of RMS residual error). Fleming and Hoffers method gave the best results for slope estimation when values of added Gaussian noise were very small compared to the mean smooth elevation difference (MSED) measured within three-by-three elevation point windows on the synthetic surface. Horns method (used in ArcInfo GRID) performed better than Fleming and Hoffers as a slope estimator when the noise amplitude was very much larger than the MSED. For the large noise amplitude situation the best overall performing method was that of Sharpnack and Akin. The popular Maximum Downward Gradient Method (MDG) performed poorly coming close to last in the rankings, for both situations, as did the Simple Method. A nonogram was produced in terms of standard deviation of the Gaussian noise and MSED values that gave the locus of the trade-off point between Fleming and Hoffers and Horns methods.     

克希霍夫叠前时间偏移技术在库车山地的应用

叠前深度偏移是解决库车山地复杂构造准确成像的较好方法,但其对速度精度要求较高,在地震数据信噪比低、速度模型不准的情况下,叠前深度偏移成像质量并不理想,因此,叠前时间偏移仍是认识该区构造的重要手段。通过实际资料处理,认为克希霍夫叠前时间偏移技术在库车山地的应用的关键点是起伏地表地震旅行时的估算和求取准确的均方根速度：前者包括从近地表面开始计算每个成像点的t0时间和该成像点道集中炮检点的旅行时;后者主要是精细的速度分析和速度扫描。该方法在库车山地实际资料处理中取得了较好的成像效果,值得进一步推广应用。     

用回弹法检测混凝土强度方法的思考

通过对回弹法检测混凝土强度、砌筑砂浆强度方法的比较,发现其计算标准差的方法有所不同.我们建议批量检测混凝土构件强度时,亦采用砂浆回弹计算标准差的方法.     

厅堂扩声系统声学特性指标测量等问题的探讨

就GB50371-2006《厅堂扩声系统设计规范》规定的“最大声压级”、“传输频率特性”、“传声增益”、“稳态声场不均匀度”和“系统总噪声”5项基本的声学特性指标,结合GB／T4959—1995《厅堂扩声特性测量方法》规定的测量方法,以使用Nor840 Real Time Analyser声学测量仪器为例,对这5项指标的测量、数据处理和结果表达方式进行阐述。