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天津市地震局于2015年通过首都圈预警示范工程项目建设，完成地震预警信息服务网络建设，并选取6所学校安装地震预警信息发布装置，提供地震预警信息示范服务，但由于信息发布装置安装复杂且价格偏高，在一定程度上影响终端设备的普及，制约地震预警信息社会化服务进程。同时，已有终端设备如同黑箱，不利于二次开发应用，存在安全隐患，影响服务质量。因此，天津市地震局积极推进基于NB-IoT技术的地震预警信息发布终端设备研制，实现低成本、低功耗、低延时目标及地震预警信息社会化服务。 相似文献
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目的：探讨针药结合治疗胃癌化疗后胃肠道不良反应寒热错杂证的临床疗效。方法：将100例化疗后产生胃肠道不良反应、辨证为寒热错杂证的胃癌患者随机分为2组，对照组49例予术后常规药物治疗，治疗组51例在对照组基础上予针刺疗法配合香砂泻心汤治疗，疗程均为4周。比较2组治疗前后中医证候积分、生活质量评分，评定综合疗效。结果：综合疗效总有效率治疗组为98.04%（50/51），对照组为83.67%(41/49)，2组比较，差异有统计学意义（P＜0.05）。治疗后2组中医证候积分较治疗前降低、生活质量评分较治疗前增高，治疗组改善均优于对照组，差异均有统计学意义（P＜0.05）。结论：针药结合治疗胃癌患者化疗后胃肠道不良反应寒热错杂证的临床疗效较好，毒副作用少，可较好地改善患者的生活质量，值得进一步深入研究。 相似文献
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基于浮游植物吸收的海洋初级生产力模型的不确定性分析 总被引：1，自引：1，他引：0
Satellite-derived phytoplankton pigment absorption(a_(ph)) has been used as a key predictor of phytoplankton photosynthetic efficiency to estimate global ocean net primary production(NPP). In this study, an a_(ph)-based NPP model(Ab PM) with four input parameters including the photosynthetically available radiation(PAR), diffuse attenuation at 490 nm(K_d(490)), euphotic zone depth(Z_(eu)) and the phytoplankton pigment absorption coefficient(a_(ph)) is compared with the chlorophyll-based model and carbon-based model. It is found that the Ab PM has significant advantages on the ocean NPP estimation compared with the chlorophyll-based model and carbonbased model. For example, Ab PM greatly outperformed the other two models at most monitoring sites and had the best accuracy, including the smallest values of RMSD and bias for the NPP estimate, and the best correlation between the observations and the modeled NPPs. In order to ensure the robustness of the model, the uncertainty in NPP estimates of the Ab PM was assessed using a Monte Carlo simulation. At first, the frequency histograms of simple difference(δ), and logarithmic difference(δ~(LOG)) between model estimates and in situ data confirm that the two input parameters(Z_(eu) and PAR) approximate the Normal Distribution, and another two input parameters(a_(ph) and K_d(490)) approximate the logarithmic Normal Distribution. Second, the uncertainty in NPP estimates in the Ab PM was assessed by using the Monte Carlo simulation. Here both the PB(percentage bias), defined as the ratio of ΔNPP to the retrieved NPP, and the CV(coefficient of variation), defined as the ratio of the standard deviation to the mean are used to indicate the uncertainty in the NPP brought by input parameter to Ab PM model. The uncertainty related to magnitude is denoted by PB and the uncertainty related to scatter range is denoted by CV.Our investigations demonstrate that PB of NPP uncertainty brought by all parameters with an annual mean of5.5% covered a range of –5%–15% for the global ocean. The PB uncertainty of Ab PM model was mainly caused by a_(ph); the PB of NPP uncertainty brought by a_(ph) had an annual mean of 4.1% for the global ocean. The CV brought by all the parameters with an annual mean of 105% covered a range of 98%–134% for global ocean. For the coastal zone of Antarctica with higher productivity, the PB and CV of NPP uncertainty brought by all parameters had annual means of 7.1% and 121%, respectively, which are significantly larger than those obtained in the global ocean. This study suggests that the NPPs estimated by Ab PM model are more accurate than others, but the magnitude and scatter range of NPP errors brought by input parameter to Ab PM model could not be neglected,especially in the coastal area with high productivity. So the improving accuracy of satellite retrieval of input parameters should be necessary. The investigation also confirmed that the SST related correction is effective for improving the model accuracy in low temperature condition. 相似文献
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传统的星载SAR数据海面风场反演方法是利用海面风场与雷达后向散射系数之间的经验关系即CMOD5模式函数求解海面风场.但在台风条件下,由于降雨对雷达信号的影响及高风速条件下CMOD5模式函数的停滞效应,海面风场的反演精度迅速下降.针对降雨对雷达信号的影响,本文基于星载SAR卫星平台未搭载降雨测量载荷的特点,将多时次的静止气象卫星红外云图用于推导台风云系的运动矢量,并由该运动矢量及非同步观测降雨数据估算星载SAR数据过境时的降雨强度.最后,利用订正模型和降雨强度数据进行降雨订正.针对高风速条件下CMOD5模式函数的停滞效应,本文基于台风的SAR图像特征和改进的HOLLAND台风模型,提出了台风参数估计及风场构建方案.首先,利用基于小波分析的风向提取算法提取台风风场的海面风向信息,并通过地球物理模式函数和风向信息反演海面风速.然后,根据台风眼的SAR图像特征计算台风中心位置和最大风速半径,并将其代入改进的HOLLAND台风模型.最后,利用中低风速数据通过最小二乘法拟合台风中心气压和最大风速,并将台风风向、中心位置、最大风速半径、中心气压和最大风速等参量代入改进的HOLLAND模型构建台风海面风场.为了验证方案的精度,选择台风"艾利"、"卡努"和"奥菲利娅"的星载SAR数据进行试验,并利用美国联合台风预警中心和飓风研究中心的最佳路径数据和风场数据进行精度检验.结果表明,本文利用星载SAR数据估算的台风中心位置、中心气压、最大风速与最佳路径数据基本一致,构建的海面风场精度较高,其中,海面风速的均方差为1.4 m s-1,风向的均方差为2.1°,为台风监测提供了新的技术途径. 相似文献
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针对微震信号采集过程中存在大量不同频率的干扰信号,导致信号初至拾取难度大的问题,提出一种经验小波变换（EWT）结合分量阈值重构规则及奇异值分解（SVD）技术对微震信号进行降噪的方法。该方法利用EWT自适应分解和抗模态混叠的特点分解微震信号,得到各分量信号。对于高信噪比信号,选取相关系数大于0.3且方差贡献率大于15%的固有模态分量进行重构,具有较好的降噪效果;对于低信噪比信号,在高信噪比降噪方法的基础上利用SVD去除高频分量中的噪声,并与EWT分解出的低频有效分量进行重构。实验表明,对不同信噪比的构造信号与实际微震信号进行降噪,信噪比均得到明显改善;以修改的能量比法和分形维数法拾取实际微震降噪信号初至到时作为验证,拾取相对误差均小于1%,证明了本文降噪方法的有效性。 相似文献
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