天线扫描对TOPSAR辐射影响的校正方法     

尹迪  韩冰  孙吉利  赵良波  洪文  胡玉新 《中国科学院大学学报》2021,38(6):791-799

TOPSAR模式是合成孔径雷达的一种宽幅成像观测模式,其产品被广泛应用于海洋风场反演、洋流反演等定量化遥感。根据TOPSAR模式成像的特点,对经典雷达方程表达式进行适应性修正,并在此基础上提出一套适用于TOPSAR模式的辐射校正处理方法,给出一套完整的处理流程图。最后,利用国产高分三号SAR卫星的TOPSAR试验模式实测数据对文中提出的校正方法进行有效性的验证工作。  相似文献   

近红外光谱分析原理、检测及定标技术简介     

高红秀  金萍  周玉岩  石瑛 《中国科技信息》2014,(3):59-61

近年来,近红外光谱技术以其独特的优越性越来越受到人们的关注,已成为发展最快、最引人注目的分析技术之一.近红外光谱技术对样品的分析要通过校正模型的建立来实现,实验结果的准确性与定标模型的可靠性有直接的关系,所以如何建立一个准确、可靠的定标模型在近红外光谱技术使用中至关重要.  相似文献   

主动进气格栅技术研究     

俞晓勇  高树亮  韦凯军  覃耿宇  郜晗 《大众科技》2016,(3)

随着主动进气格栅技术在汽车上的逐步使用,主动进气格栅的技术优势逐步体现,文章阐述了主动进气格栅对整车行驶阻力的优化和整车热控制的相关影响,并以线性回归模型的方法对主动进气格栅的标定方法进行了初步探索。  相似文献   

湿敏元件及湿度传感器常用的测量装置     

张广学  郝雁  周明军  卢崇考 《中国科技信息》2005,(12):62-63

介绍了湿敏元件及湿度传感器常用的测量装置及基本原理。论述了各种测量装置所能达到的测量精度及适用范围。同时指出正确使用双压法、双温法、分流法及饱和盐法湿度发生装置对于保证湿敏元件及湿度传感器测量至关重要。  相似文献   

谈可燃气体报警器的校正     

金海庆 《大众科技》2011,(10):162-163,165

介绍目前工业生产及公共安全方面常用各种可燃气体报警器的传感器一般原理及如何对其进行合理、有效的校正,并对一些校正过程中可能遇到的问题予以说明和讲解。  相似文献   

化学计量学中几种常用多变量校正法的应用     

李生英  卢小泉 《天水师范学院学报》2003,23(2):26-27

作为化学量测的基础理论和方法学，化学计量学的应用非常广泛。尤其在分析检测多组分体系中具有快速、准确、简便的特点。根据近年来的相关文献，LS、PLS、KF及TFA等几种常用的多变量校正法在分析化学等领域具有极其广泛的应用。  相似文献   

Comparison of methods for determining power generated on a rope-braked cycle ergometer during low-intensity exercise     

K. L. Franklin  R. S. Gordon  J. S. Baker  B. Davies 《Sports Engineering》2006,9(1):29-38

This study compares the instrumentation and analysis techniques used when determining the power expended pedalling a rope-braked ergometer manufactured by Monark (Sweden) during a low intensity test. Power values were generated by eight subjects. The instrumentation consisted of load cells to measure the rope brake forces, a tachometer to measure the flywheel velocity and instrumented pedal cranks manufactured by Schoberer Rad Messtechnik (SRM). The subjects pedalled a rope-braked ergometer at 60 rev min^-1, against a resistance of 3 kg, for 5 minutes. Three different measurements of the mean power were recorded and these were compared with the value given by Monark. The SRM cranks provided two sets of results using different software packages supplied with the cranks. SRM standard software is used for taking measurements during training and cycle races over long time periods. An additional piece of software is provided by SRM called Ptnew, which gives readings of torque and pedal cadence over periods up to 30 seconds. Using the values supplied by Monark each subject generated 180 W of power. The mean power for the eight subjects, measured using the SRM cranks, was 170.36 W (SD 4.11) using the alternative SRM software (Ptnew) over a 30 second period and 173.68 W (SD 2.21) using the standard SRM software. From the direct measurement of the brake forces and flywheel velocity the mean power across the eight subjects was 148.90 W (SD 5.89). The SRM cranks measure the input power, whereas the direct measurement system measures the power output excluding mechanical losses. These values give a figure for the mechanical efficiency for the roped-braked ergometer of 88%. It was found that Monark overestimates the power generated by the subjects when compared with both the SRM systems and the direct measurement instrumentation.  相似文献   

Benchmarking the performance of Bhutanese students with the performance of the students from the OECD's PISA countries     

Gembo Tshering  Vaughan Prain 《Educational Research and Evaluation》2013,19(4):263-281

Setting international benchmarks for education systems of the Organisation for Economic Co-operation and Development (OECD) countries is one of the goals of the OECD's Programme for International Student Assessment (PISA). However, some countries are not able to participate in PISA, despite their desire to set international benchmarks for their education systems. This article presents a method of setting international benchmarks for a country's school education system, without necessarily participating in PISA, by designing a test using the test items released by PISA for public consumption. The method has been implemented in a study that involved 1,500 Grade 10 students across 60 schools in Bhutan. The students were administered a mathematics test constructed from the PISA Mathematical Literacy test items. The study showed that the performance of Bhutanese students was comparable with the performance of the students from the countries that participated in PISA 2003 and that Bhutan could learn from both high- and low-performing school education systems of those countries.  相似文献   

Cut points of the Actigraph GT9X for moderate and vigorous intensity physical activity at four different wear locations     

Matthew B. Rhudy  Scott B. Dreisbach  Matthew D. Moran  Marissa J. Ruggiero  Praveen Veerabhadrappa 《Journal of sports sciences》2020,38(5):503-510

ABSTRACT

Accelerometer cut points are an important consideration for distinguishing the intensity of activity into categories such as moderate and vigorous. It is well-established in the literature that these cut points depend on a variety of factors, including age group, device, and wear location. The Actigraph GT9X is a newer model accelerometer that is used for physical activity research, but existing cut points for this device are limited since it is a newer device. Furthermore, there is not existing data on cut points for the GT9X at the ankle or foot locations, which offers some potential benefit for activities that do not involve arm and/or core motion. A total of N = 44 adults completed a four-stage treadmill protocol while wearing Actigraph GT9X sensors at four different locations: foot, ankle, wrist, and hip. Metabolic Equivalent of Task (MET) levels assessed by indirect calorimetry along with Receiver Operating Characteristic (ROC) curves were used to establish cut points for moderate and vigorous intensity for each wear location of the GT9X. Area under the ROC curves indicated high discrimination accuracy for each case.  相似文献   

基于遗传算法的阵列相位误差校正     

刘颖 《天津工程师范学院学报》2007,17(3):26-28,32

针对声纳水听器阵列比较突出的相位误差,研究了一种基于遗传算法的阵列校正方法。该方法利用无相位误差时阵列协方差矩阵具有Toeplitz结构的特性构造代价函数,并以此作为遗传算法中进化个体的适应度函数,由算法搜索的最优个体得到阵元相位误差的估值。计算机仿真结果表明,该方法可以明显地减小阵列相位误差对MUSIC算法DOA估计结果的影响。  相似文献