Estimation of the proportion ratio under a simple crossover trial

The proportion ratio (PR) of patient response is one of the most commonly used indices for measuring the relative treatment effect in a randomized clinical trial (RCT). Assuming a random effect multiplicative risk model, we develop two point estimators and three interval estimators in closed forms for the PR under a simple crossover RCT. On the basis of Monte Carlo simulation, we evaluate the performance of these estimators in a variety of situations. We note that the point estimator using a ratio of two arithmetic means of patient response probabilities over the two groups (distinguished by the order of treatment-received sequences) is generally preferable to the corresponding one using a ratio of two geometric means of patient response probabilities. We note that the three interval estimators developed in this paper can actually perform well with respect to the coverage probability when the number of patients per group is moderate or large. We further note that the interval estimator based on the ratio of two arithmetic means of patient response probabilities with the logarithmic transformation is probably the best among the three interval estimators discussed here. We use a simple crossover trial studying the suitability of two new inhalation devices for patients who were using a standard inhaler device delivering Salbutamol published elsewhere to illustrate the use of these estimators.     

Step-up and step-down procedures controlling the number and proportion of false positives

In multiple hypotheses testing, it is important to control the probability of rejecting “true” null hypotheses. A standard procedure has been to control the family-wise error rate (FWER), the probability of rejecting at least one true null hypothesis.For large numbers of hypotheses, using FWER can result in very low power for testing single hypotheses. Recently, powerful multiple step FDR procedures have been proposed which control the “false discovery rate” (expected proportion of Type I errors). More recently, van der Laan et al. [Augmentation procedures for control of the generalized family-wise error rate and tail probabilities for the proportion of false positives. Statist. Appl. in Genetics and Molecular Biol. 3, 1-25] proposed controlling a generalized family-wise error rate k-FWER (also called gFWER(k)), defined as the probability of at least (k+1) Type I errors (k=0 for the usual FWER).Lehmann and Romano [Generalizations of the familywise error rate. Ann. Statist. 33(3), 1138-1154] suggested both a single-step and a step-down procedure for controlling the generalized FWER. They make no assumptions concerning the p-values of the individual tests. The step-down procedure is simple to apply, and cannot be improved without violation of control of the k-FWER.In this paper, by limiting the number of steps in step-down or step-up procedures, new procedures are developed to control k-FWER (and the proportion of false positives) PFP. Using data from the literature, the procedures are compared with those of Lehmann and Romano [Generalizations of the familywise error rate. Ann. Statist. 33(3), 1138-1154], and, under the assumption of a multivariate normal distribution of the test statistics, show considerable improvement in the reduction of the number and PFP.     

基于散度比例准则的高分辨距离像特征提取

针对传统线性判别分析(LDA)的子空间倾向于保留大类间距离类对的可分性,而丢弃小类间距离类对的可分性的问题,基于子空间应均衡保留各类对可分性的思想,提出一种新的准则——散度比例(PD)准则。PD准则为各类对子空间散度与原空间散度之比的均值,并推导出最大化PD准则的线性判别分析(PD-LDA)的求解过程。采用PD-LDA对高分辨距离像(HRRP)的幅度谱进行特征提取,基于外场实测数据,分别训练了最小欧氏距离分类器和支持向量机(SVM)分类器,两种分类器的识别结果均表明,PD-LDA相比LDA,可显著降低数据维数并有效提高识别率。     

An extension of likelihood-ratio-test for testing linear hypotheses in the baseline-category logit model

A new family of test statistics for testing linear hypotheses in baseline-category logit models is introduced and its asymptotic distribution is obtained. The new family is a natural extension of the classical likelihood ratio test. A simulation study is carried out to find new test statistics that offer an attractive alternative to the classical likelihood ratio test in terms of both exact size and exact power.     

Estimation and Ranking of Alternatives under Interval Uncertainty

A method is proposed to estimate and rank alternative decisions with interval representation of their characteristics. The method is verified experimentally. __________ Translated from Kibernetika i Sistemnyi Analiz, No. 4, pp. 148–153, July–August 2005.     

Java程序中数组越界和空指针错误的静态分析

介绍了静态分析的相关背景知识,对Java程序中数组越界和空指针错误的常见表现形式进行了归类,并通过实验评估了现有的Java静态分析工具功能,指出了其在跨过程分析中的不足,并对如何改进进行了讨论。     

物联网框架下PM2.5高精度测试模型仿真分析

对空气中的PM2.5颗粒污染物进行准确测试,有利于控制大气污染.PM2.5颗粒较小,在风速、大气环境等复杂因素的影响下,PM2.5污染物扩散过程在空气中呈现高度的随机性,污染物扩散过程无法约束,污染物在空气中呈现实时不均匀分布.传统的物联网环境下空气PM2.5污染物检测方法,仅仅对小区域的PM2.5测试结果进行测试,通过把不同区域的结果进行加权求平均,完成大区域检测,没有考虑扩散过程中颗粒物的扩散不均匀造成小区域测试结果的实时变化,测试结果不准.提出采用多信号融合估计算法的物联网框架下PM2.5高精度测试模型.建立粗糙集神经网络模型,将所有的物联网框架下PM2.5输入到该模型中,输出的结果是PM2.5高精度测试结果.针对PM2.5高精度测试结果来自于不同的区域,利用多信号融合估计方法对数据进行约束融合,得到PM2.5高精度测试非线性约束下的结果.实验结果表明,利用改进算法进行物联网框架下PM2.5高精度测试,能够极大的提高测试的准确性.     

基于密度的K-means算法在轨迹数据聚类中的优化

针对传统的K-means算法无法预先明确聚类数目,对初始聚类中心选取敏感且易受离群孤点影响导致聚类结果稳定性和准确性欠佳的问题,提出一种改进的基于密度的K-means算法。该算法首先基于轨迹数据分布密度和增加轨迹数据关键点密度权值的方式选取高密度的轨迹数据点作为初始聚类中心进行K-means聚类,然后结合聚类有效函数类内类外划分指标对聚类结果进行评价,最后根据评价确定最佳聚类数目和最优聚类划分。理论研究与实验结果表明,该算法能够更好地提取轨迹关键点,保留关键路径信息,且与传统的K-means算法相比,聚类准确性提高了28个百分点,与具有噪声的基于密度的聚类算法相比,聚类准确性提高了17个百分点。所提算法在轨迹数据聚类中具有更好的稳定性和准确性。     

Estimation of fractional integration in the presence of data noise

A comparative study is presented regarding the performance of commonly used estimators of the fractional order of integration when data is contaminated by noise. In particular, measurement errors, additive outliers, temporary change outliers, and structural change outliers are addressed. It occurs that when the sample size is not too large, as is frequently the case for macroeconomic data, then non-persistent noise will generally bias the estimators of the memory parameter downwards. On the other hand, relatively more persistent noise like temporary change outliers and structural changes can have the opposite effect and thus bias the fractional parameter upwards. Surprisingly, with respect to the relative performance of the various estimators, the parametric conditional maximum likelihood estimator with modelling of the short run dynamics clearly outperforms the semiparametric estimators in the presence of noise that is not too persistent. However, when a non-zero mean is allowed for, it may reverse the conclusion.     

强干扰下基于联合技术的信源参数估计

针对强干扰情况,提出一种联合技术估计信源参数。利用干扰正交补子空间消除干扰信号,运用正则相关技术在高斯色噪声和高斯白噪声下估计信号源个数,并估计信号波达方向。仿真验证了这种联合技术的有效性。     

Estimation of net radiation from the MODIS data under all sky conditions: Southern Great Plains case study

Net radiation is a key component in the surface radiation budget. Numerous studies have developed frameworks to estimate net radiation or its components (upwelling or downwelling longwave and/or shortwave radiation) from remote sensing data for clear sky conditions. Application of existing methodologies to estimate net radiation for cloudy sky conditions from remote sensing sensors remains a significant challenge. In this paper, we present a framework to estimate instantaneous and daily average net radiation under all sky conditions from using the data from the MODerate Resolution Imaging Spectroradiometer (MODIS), onboard from the Terra satellites. Bisht et al. (2005) methodology is used for the clear sky portion of the MODIS overpass; while for cloudy portion of the MODIS overpass an extension of Bisht et al. (2005) methodology is applied. The extension of Bisht et al. (2005) methodology utilizes the MODIS cloud data product (MOD06_L2) for cloud top temperature, cloud fraction, cloud emissivity, cloud optical thickness and land surface temperature for cloudy days. The methodology is applied over the Southern Great Plains (SGP) for a time period covering all seasons of 2006. During the MODIS-Terra overpasses in 2006 over the SGP, only 24% of day-overpasses and 9% of night-overpasses had 75% or more of the study region as cloud free. Thus, this proposed study is applicable to a large portion of the MODIS-Terra overpasses. The root mean square errors (RMSE) of instantaneous and daily average net radiation estimated under cloudy conditions using the MOD06_L2 product, comparing to ground-based measurements are 37 W m^− 2 and 38 W m^− 2, respectively. The strength of the proposed methodology is that it can rely exclusively on remote sensing data in the absence of ancillary ground observations, thus it has a potential to estimate surface energy budget globally.     

网络入侵联机感染扩散过程的研究与仿真

在网络病毒扩散估计的研究中,对网络入侵联机感染扩散过程的研究有利于控制病毒入侵过程.在网络入侵影响下,网络联机感染扩散过程具有较强随机性和不可控扩散性的特点,不只是呈现简单的扩散叠加特征.利用传统感染扩散过程评估模型进行网络入侵联机感染扩散过程估计,存在无法在网络建模中有效界定网络入侵强度的难点,因为入侵强度无法预判,都是假设网络入侵强度在一定时间处在一定的权值内,存在较大误差,将会导致联机感染扩散过程估计的结果不准确.提出一种基于多级模糊概率的网络入侵联机感染扩散过程估计方法.利用数据融合方法针对网络入侵和联机感染扩散过程的相关参数进行实时融合,以实时叠加的方式准确掌握入侵强度特征.根据强度特征设定网络入侵因子进行模糊概率评估,利用模糊概率方法建立多级模糊概率的联机感染扩散过程模型.实验结果表明,利用上述方法进行网络入侵联机感染扩散过程估计,能够提高估计的准确性.     

Estimation of daily actual evapotranspiration from remotely sensed data under complex terrain over the upper Chao river basin in North China

Daily actual evapotranspiration over the upper Chao river basin in North China on 23 June 2005 was estimated based on the Surface Energy Balance Algorithm for Land (SEBAL), in which the parameterization schemes for calculating the instantaneous solar radiation and daily integrated radiation were improved by accounting for the variations in slope and azimuth of land surface and terrain shadow in mountainous areas. The evapotranspiration (ET) estimated from satellite data in this study for the whole watershed ranges from 0 mm to 7.3 mm day^?1 with a mean of 3.4 mm day^?1, which was validated by Penman–Monteith approaches for water body and paddy land. The comparison of ET estimates for a wide range of land cover types reflected distinct mechanisms of energy partition and water removal of various land cover types, showing differences in the spatial distribution pattern of ET, which could be not only the reflection but also the driving force of advection and local circulation that may violate the surface energy balance equation in the vertical direction. The spatial variation in daily solar radiation and ET estimates under the complex terrain of forest land were elaborated and evaluated by exploring the relationship between ET estimates and elevations for wood land and grass land. In addition, the utility and limitations of SEBAL's applicability to watersheds with various land cover types and complex terrain were analysed.     

Energy-efficient routing technique for reliable data transmission under the background of big data for disaster region

Big data analysis and cloud computing are gaining much interest in various applications including disaster management. One of the major difficulties in the process of exchanging environmental data in the disaster affected areas has been considered as one of the emerging areas of research. This research focuses on maintaining the environmental data information management of the disaster affected areas, where the intermediate node has been used to transmit the information during transmission and an optimized routing has been used to create efficient data transmission, such as temperature, pressure, humidity, and the level of pollution within the network. The intermediate node may also be hacked during data processing. In this article, the efficient big data-based clustering technique has been proposed. In this research, the information is grouped into a cluster in every comparable node and the energy consumption has been efficiently managed with the hybrid metaheuristic optimization-based effective routing technique. The system excellence has been evaluated using the energy utilization factor, packet delivery ratio, and attack-free routing effectiveness metrics to handle environmental information on disaster affected areas.     

高分辨率遥感影像GeoEye-1在黑河下游柽柳生物量估算中的应用

以黑河下游绿洲柽柳为研究对象,利用高分辨率遥感影像GeoEye-1柽柳分类结果,基于典型样点生物学特性调查与生物量试验,建立柽柳冠幅面积与生物量关系模型,计算研究区柽柳地上部分的生物量,分析黑河0~2、2~5、5~10与10~15 km不同缓冲带柽柳生物量空间分布规律。结果显示:研究区柽柳总生物量为4.10×10⁵ t,其中:0~2、2~5、5~10与10~15 km缓冲带内柽柳生物量分别为2.34×10⁵、1.07×10⁵、6.35×10⁴和5.17×10³ t。河流距离对柽柳生物量影响显著,单位面积柽柳生物量随着与河流距离的增加而减少,二者相关系数为-0.97。     

“双高”背景下高校行政管理效能提升探究

2019年12月,教育部正式公布中国特色高水平高职学校和专业建设计划首批建设单位名单,这是国家在职业教育领域的一项重大决策建设工程。高水平的办学能力就需要高水平的管理能力,这就对高职院校信息化建设及行政管理工作提出了更高的要求。本文将主要探究高职院校行政管理中存在的问题,并提出相应的策略。     

Estimation of winter wheat phenology under the influence of cumulative temperature and soil salinity in the Yellow River Delta,China, using MODIS time-series data

Understanding the impact of environmental factors on crop phenology is significant in predicting crop growth stages, agricultural decision-making, and yield estimation. Here, using Moderate Resolution Imaging Spectroradiometer time-series data, we present phenological detection mechanisms and an explanation for the phenological variability linked to environmental drivers, such as cumulative temperature and soil salinity, for winter wheat (Triticum aestivum L.) in the Yellow River Delta in 2013. The 8-day normalized difference vegetation index was fitted to a double Gaussian function. Phenological phases, such as the green-up and heading phases, were extracted using maximum curvature approaches. The spatial characteristics of the phenological patterns were investigated. The relationships between the phenological phases and cumulative temperature were explored. Then, the relationships between the phenological phases and soil salinity were evaluated by selecting sites with similar soil fertility and temperature forcing. This study concluded that the regional average green-up date occurred on 5 March, and the regional average heading date occurred on 9 May. The spatial distributions of the green-up and heading phases showed a gradual delay from the southwest to the northeast and from the south to the north. The green-up phase lagged 4–5 days for every 10 degree days that the cumulative temperature decreased. The heading phase lagged 1–2 days for every 10 degree days that the cumulative temperature decreased. The green-up phase in a non-salinization region might be approximately 5–9 days earlier than that in a severe or moderate salinization region. The heading phase in a severe region might occur approximately 1–8 days earlier than that in a non-salinization or moderate salinization region. The method proposed in this article may be useful for understanding the impact of temperature and soil salinity on phenology and could be used to better manage winter wheat in coastal salinization areas.     

Predicting slips based on the STM 603 whole-footwear tribometer under different coefficient of friction testing conditions

Assessing footwear slip-resistance is critical to preventing slip and fall accidents. The STM 603 (SATRA Technology) is commonly used to assess footwear friction but its ability to predict human slips while walking is unclear. This study assessed this apparatus’ ability to predict slips across footwear designs and to determine if modifying the test parameters alters predictions. The available coefficient of friction (ACOF) was measured with the device for nine different footwear designs using 12 testing conditions with varying vertical force, speed and shoe angle. The occurrence of slipping and the required coefficient of friction was quantified from human gait data including 124 exposures to liquid contaminants. ACOF values varied across the test conditions leading to different slip prediction models. Generally, a steeper shoe angle (13°) and higher vertical forces (400 or 500?N) modestly improved predictions of slipping. This study can potentially guide improvements in predictive test conditions for this device.

Practitioner Summary: Frictional measures by the STM603 (SATRA Technology) were able to predict human slips under liquid contaminant conditions. Test parameters did have an influence on the measurements. An increased shoe-floor testing angle resulted in better slip predictions than test methods specified in the ASTM F2913 standard.     

RBF在钢铁材质缺陷检测中的应用研究

针对钢铁件材质缺陷检测问题,介绍了基于初始幅值磁导率法的一种电磁无损检测方法。为了提高检测的效率和准确率,将RBF神经网络设计成为新的识别系统通过对钢铁件样本数据进行的仿真测试表明,RBF神经网络系统识别效率较高且可靠,为电磁无损检测提供了一个新的思路。     

On the Feasibility of Time Estimation under Isolation Conditions in Wireless Sensor Networks

We study the problem of providing a sensor with an accurate estimate of the time, from a novel perspective which is complementary to the well-studied clock synchronization problem. More precisely, we analyze the case in which a sensor node is temporarily unable to run a clock synchronization protocol due to failures or intermittent connectivity, or is willing to skip one or more clock adjustments to save energy, but still requires an accurate estimate of the reference time. We propose and analyze two simple and efficient clock reading methods, one deterministic and the other probabilistic, which are designed to work in synergy with a clock synchronization protocol. Our deterministic method achieves a better time accuracy by exploiting information regarding the sign of the deviation of the hardware clock from the reference time. This algorithm leads to noticeable energy savings since it can be applied to reduce the frequency of the periodic clock adjustments by a factor of 2, while maintaining the same error bound. Moreover, our method is of theoretical interest since it shows how a stronger but realistic clock model leads to a refinement of the optimality bound for the maximum deviation of a clock that is periodically synchronized. We also propose two simple versions of this algorithm: a method that guarantees the monotonicity of the clock values, and a generalization that improves the accuracy in case of clock stability. Our probabilistic method is based on time series forecasting, and provides a probabilistically accurate estimate of the reference time with a constant error bound. It is more flexible than our previous methods since it does not depend on the frequency at which clock synchronization occurs, and can be dynamically tuned according to the application requirements and resource availability. All these methods have broad applicability for their generality. In sensor networks they can be applied to improve the clock accuracy of a sensor node in conditions of network isolation, or to reduce the frequency of the clock adjustments, thus saving energy and increasing the system lifetime.