不同组合比例煤岩的电荷感应与微震规律试验研究

针对煤岩在屈服破坏过程中有微震和电荷信号产生这一特征,利用自行设计的微震和电荷感应信号监测试验系统,分析不同组合比例煤岩在变形破裂过程中微震和电荷信号的变化规律。研究结果表明:微震和电荷信号是低频信号,信号频谱集中分布在0~80 Hz,应力突变与微震信号和电荷信号的产生及变化有较好的一致性;随着“煤-岩”高度比的增加,试样的单轴抗压强度减小,试样屈服破裂时微震和电荷信号幅值增大,同步性增强,试件破坏的突发性增强;试件破坏过程中电荷比微震信号数更多,初次明显的电荷信号也早于初次明显的微震信号。     

基于船舶操纵模拟的船撞桥概率研究

针对船舶在桥区水域航行过程中撞击桥墩的碰撞概率问题,建立并验证了船舶操纵数学模型,模拟了船舶在不同风、水流等条件下的航行情况,改进了AASHTO船舶撞桥概率模型中几何概率的算法,提出了以模拟试验样本的航迹带中心位置坐标为均值,以模拟实验样本结果计算的方差为方差的几何概率模型,同时引入停船概率模型。将改进后的模型应用于北江油金大桥船舶操纵模拟及船撞概率的研究,预测2020年北江油金大桥受上行船舶碰撞年频率大约2.81×10-6次/a,受下行船舶碰撞年频率3.43×10-4次/a,总碰撞频率3.461×10-4次/a。     

A model of rainfall redistribution in terraced sandy grassland landscapes

A simple model of rainfall redistribution within a terraced sandy grassland landscape has been developed. The model assumes that rainfall redistribution is driven by rainfall impulses and is controlled by characteristic field capacity of soils. When the rainfall intensity is large enough to render soil water content greater than its characteristic field capacity, the excessive soil water can drain very quickly by means of large amounts of non-capillary pores of sandy soils or by means of surface runoff. Exponential distribution of rainfall impulses was assumed and tested with measured daily rainfall at two meteorological stations in the sandy grassland area of north China. The model was solved to give the equivalent rainfall at each terrace in the landscape.     

Estimating the complexity of bird song by using capture-recapture approaches from community ecology

Repertoire size, the number of unique song or syllable types in the repertoire, is a widely used measure of song complexity in birds, but it is difficult to calculate this exactly in species with large repertoires. A new method of repertoire size estimation applies species richness estimation procedures from community ecology, but such capture-recapture approaches have not been much tested. Here, we establish standardized sampling schemes and estimation procedures using capture-recapture models for syllable repertoires from 18 bird species, and suggest how these may be used to tackle problems of repertoire estimation. Different models, with different assumptions regarding the heterogeneity of the use of syllable types, performed best for different species with different song organizations. For most species, models assuming heterogeneous probability of occurrence of syllables (so-called detection probability) were selected due to the presence of both rare and frequent syllables. Capture-recapture estimates of syllable repertoire size from our small sample did not differ significantly from previous estimates using larger samples of count data. However, the enumeration of syllables in 15 songs yielded significantly lower estimates than previous reports. Hence, heterogeneity in detection probability of syllables should be addressed when estimating repertoire size. This is neglected using simple enumeration procedures, but is taken into account when repertoire size is estimated by appropriate capture-recapture models adjusted for species-specific song organization characteristics. We suggest that such approaches, in combination with standardized sampling, should be applied in species with potentially large repertoire size. On the other hand, in species with small repertoire size and homogenous syllable usage, enumerations may be satisfactory. Although researchers often use repertoire size as a measure of song complexity, listeners to songs are unlikely to count entire repertoires and they may rely on other cues, such as syllable detection probability.Communicated by A. Cockburn     

Variance estimation in the EMAP strategy for sampling discrete ecological resources

The United States Environmental Protection Agency's Environmental Monitoring and Assessment Program (EMAP) is designed to describe status, trends and spatial pattern of indicators of condition of the nation's ecological resources. The proposed sampling design for EMAP is based on a triangular systematic grid and employs both variable probability and double sampling. The Horvitz-Thompson estimator provides the foundation of the design-based estimation strategy used in EMAP. However, special features of EMAP designed to accommodate the complexity of sampling environmental resources on a national scale require modifications of standard variance estimation procedures as well as development of new techniques. An overview of variance estimation methods proposed for application to EMAP's sampling strategy for discrete resources is presented.     

用同位素标记LZF—1 DNA指纹探针进行人的DNA指纹分析

同位素γ－32P－ATP对LZF－1DNA指纹探针作5＇末端标记后，检测成都地区人群中84名随机个体的DNA指纹，获得了清晰易辨的具有高度个体特异性的DNA指纹图谱．谱带平均数为17．667条，平均等位基因频率为0．167，探针的鉴别机率为4．862×10－10．表明LZF－1DNA指纹探针完全达到了法医学检验中鉴别个体的目的．     

Desirable design characteristics for long-term monitoring of ecological variables

Long-term environmental monitoring places a set of demands on a sampling strategy not present in a survey designed for a single time period. The inevitability that a sample will become out of date must be a dominant consideration in planning a long-term monitoring programme. The sampling strategy must be able to accommodate periodic frame update and sample restructuring in order to address changes in the composition of the universe and changes in the perception of issues leading to new questions and concerns. The sampling strategy must be capable of adapting to such changes while maintaining its identification as a probability sample and its capacity to detect trends that span the update occasions. These issues are examined with respect to sub-population estimation, post-stratification via conditioning, and sample enlargement and reduction. Design features that involve complex sample structure create potentially serious difficulties, whereas an equal probability design permits greater adaptability and flexibility. Structure should be employed sparingly and in awareness of its undesirable effects.     

Resampling from stochastic simulations

To model the uncertainty of an estimate of a global property, the estimation process is repeated on multiple simulated fields, with the same sampling strategy and estimation algorithm. As opposed to conventional bootstrap, this resampling scheme allows for spatially correlated data and the common situation of preferential and biased sampling. The practice of this technique is developed on a large data set where the reference sampling distributions are available. Comparison of the resampled distributions to that reference shows the probability intervals obtained by resampling to be reasonably accurate and conservative, provided the original and actual sample has been corrected for the major biases induced by preferential sampling.Andre G. Journel is a Professor of Petroleum Engineering at Stanford University with a joint appointment in the Department of Geological and Environmental Sciences. He is, also, Director of the Stanford Center for Reservoir Forecasting. Professor Journel has pioneered applications of geostatistical techniques in the mining/petroleum industry and extended his expertise to environmental applications and repository site characterization. Most notably, he developed the concept of non-parametric geostatistics and stochastic imaging with application to modeling uncertainty in reservoir/site characterization. Although the research described in this article has been supported by the United States Environmental Protection Agency under Cooperative Agreement CR819407, it has not been subjected to Agency review and therefore does not necessarily reflect the views of the Agency and no official endorsement should be inferred.     

Crop Failure in Dalocha, Ethiopia: A Participatory Emergency Response

This case study of an NGO's response to a food crisis due to crop failure focuses on the extent of active community participation at each stage of the project. With the current debate on the relationship between relief and development, and in particular the focus on encouraging more active community participation in relief responses, this study has relevance both in the Ethiopian context and beyond.
In this example the participation process was greatly facilitated by the prior relationship between the international NGO and the communities, and also by the high level of staff input into the project. Where resources or conditions are less favourable, as might be the case in similar responses by local NGOs or government agencies, the paper suggests that the participatory approach can be adapted or partially implemented and still result in a more effective and locally relevant operation.     

Tired of innovations? Learned helplessness and fatigue in the context of continuous streams of innovation implementation

The business environment faced by contemporary organizations is highly uncertain and constantly changing. Thus, organizations have adopted and implemented a continuous stream of innovations to achieve sustainable growth and survival. Considering the demand for additional resources to implement innovations, the present study explores organizational conditions that may lead to innovation‐targeted burnout and fatigue among employees, which impede their active participation in a subsequent innovation. To this end, we propose a theoretical framework that elucidates the effects of previous innovations on the subsequent implementation behavior of employees. We identify two dimensions of the cognitive appraisal of previous innovations (i.e., intensity and failure) that shape employees' beliefs regarding innovations, such as innovation‐targeted helplessness, which ultimately results in innovation fatigue. Data collected from 84 managers and 397 employees of Chinese and Korean organizations prove the significant role of employee perceptions of previous innovations in shaping the innovation‐targeted helplessness and fatigue of employees, which ultimately affect employee behavior toward a subsequent innovation. The present conceptual and empirical analyses suggest that given continuous streams of innovation implementation, managers should carefully consider employee's perceptions of previous innovations (i.e., intensity and failure) for successful implementation of a subsequent innovation. Copyright © 2017 John Wiley & Sons, Ltd.