Estimation of weibull location

A simulation study was carried out to compare the performances of two different simple estimators of the location parameter for a three-parameter Weibull distribution Both Estimators have been suggested by recent paper in the literature. Bras and mean square error are examined for many different sample-size and shape-parameter-value combinations. Strong evidence of the domination of one estimator over the other is found.     

Modeling stereotypes and negative self‐stereotypes as a function of interactions among groups with power asymmetries

Stereotypes is one of the most researched topics in social psychology. Within this context, negative self‐stereotypes pose a particular challenge for theories. In the current work, we propose a model that suggests that negative self‐stereotypes can theoretically be accounted for by the need to communicate in a social system made up by groups with unequal power. Because our theory is dynamic, probabilistic, and interactionist, we use a computational simulation technique to show that the proposed model is able to reproduce the phenomenon of interest, to provide novel accounts of related phenomena, and to suggest novel empirical predictions. We describe our computational model, our variables' dynamic behavior and interactions, and link our analyses to the literature on stereotypes and self‐stereotypes, the stability of stereotypes (in particular, gender and racial stereotypes), the effects of power asymmetries, and the effects of intergroup contact.     

Researcher reflexivity: exploring the impacts of CAQDAS use

Computer-assisted qualitative data analysis software (CAQDAS) programs are established tools for qualitative research. Making informed decisions when using them requires researchers to understand how they affect research practices and outcomes. In this article we consider the impact of CAQDAS on researcher reflexivity. Reviewing three decades of literature, we identify specific ‘reflexive moments’ experienced by CAQDAS users, the contexts in which they occur, the issues they raise, and the reflexive awareness they generate. The ways in which CAQDAS can enhance or undermine researcher reflexivity are also reported. By doing so, we aim to help researchers and especially research students (and their supervisors) understand the relationship between CAQDAS and reflexivity and the reflexive moments they may encounter when using such software.     

汽车侧围外板尾翼拉延成型工艺改善研究

为解决汽车侧围外板尾翼在拉延成型后出现起皱和开裂的问题，设计了3种造型方案.通过造型设计分析及Autoform模拟，对比3种方案，对原工艺进行整改和优化，得到了抬高造型台阶面的最优造型方案.该方案能改善进料速度、增加材料流动性，有效地消除开裂、起皱的缺陷，对同类和其他类似产品的冲压工艺设计具有参考意义.     

Efficient heterogeneous sampling for stochastic simulation with an illustration in health care applications

In modeling disease transmission, contacts are assumed to have different infection rates. A proper simulation must model the heterogeneity in the transmission rates. In this article, we present a computationally efficient algorithm that can be applied to a population with heterogeneous transmission rates. We conducted a simulation study to show that the algorithm is more efficient than other algorithms for sampling the disease transmission in a subset of the heterogeneous population. We use a valid stochastic model of pandemic influenza to illustrate the algorithm and to estimate the overall infection attack rates of influenza A (H1N1) in a Canadian city.     

利用数学软件复原碎纸片的方法

研究了碎纸片的拼接复原问题,建立了合理有效的碎纸片拼接复原的数学模型；给出了数学软件实现自动拼接的具体算法；结合人工拼接得出复原图片；最后,对所给的拼接方法提出了改进方向.     

Producing public goods in networks: Some effects of social comparison and endogenous network change

As actors participate in the production of public goods, processes of social comparison may affect the decisions about the individual contributions as well as the endogenously changing structure of an underlying social network. This leads to the transformation of an ordinary n-player Prisoner's Dilemma of collective action into an n-player coordination game. The paper uses agent-based simulations to trace the formation of public goods while varying network characteristics, such as density, segregation, or the strength of relationships. Additionally, the usage of both a forward- and a backward-looking agent model shows possible implications of different assumptions about the actors’ decision making.     

Use of multiple cluster analysis methods to explore the validity of a community outcomes concept map

Concept mapping is now a commonly-used technique for articulating and evaluating programmatic outcomes. However, research regarding validity of knowledge and outcomes produced with concept mapping is sparse. The current study describes quantitative validity analyses using a concept mapping dataset. We sought to increase the validity of concept mapping evaluation results by running multiple cluster analysis methods and then using several metrics to choose from among solutions. We present four different clustering methods based on analyses using the R statistical software package: partitioning around medoids (PAM), fuzzy analysis (FANNY), agglomerative nesting (AGNES) and divisive analysis (DIANA). We then used the Dunn and Davies-Bouldin indices to assist in choosing a valid cluster solution for a concept mapping outcomes evaluation. We conclude that the validity of the outcomes map is high, based on the analyses described. Finally, we discuss areas for further concept mapping methods research.     

高含水期复杂断块油藏剩余油分布及挖潜

高含水期陆相复杂断块层状油藏剩余油分布复杂,油藏模拟难度大。马11复杂断块油藏在油藏精细描述基础上,利用动静态综合分析研究与密网格大规模数值模拟研究相结合,提高了剩余油研究精度和可信度;在此基础上,针对油藏剩余油分布特点并结合当前经济技术条件,部署实施了以调整井、调剖、堵水、油水井大修为主的剩余油挖潜方案,油藏含水上升率大幅度下降、采油速度上升、采收率提高了。     

网络直播聚合犯罪的罪因、特征与治理措施

网络直播聚合犯罪愈演愈烈，主要集中于知识产权犯罪和色情犯罪领域，国内目前对该类犯罪的研究较少。网络直播聚合犯罪与社会结构方面的紧张、个人违法性意识方面的紧张存在关系，前者主要体现为：商品拜物教影响下的部分民众设定目标时日益以物质获得为参考系；阶层固化使得处于部分底层民众无法通过制度性手段实现目标。后者主要体现为网络直播聚合犯罪者实施犯罪，与其权衡犯罪成本与获利数额、心存侥幸有关。在对案例进行实证分析的前提下，归纳概括出此类犯罪的三个主要特征：犯罪主体呈现出低龄化、学历较低、无业状态较多的特点；分工的复杂性、网络的匿名性使得犯罪的隐蔽性较强；黑灰产业链业已形成并成熟。对此类犯罪的治理，应当坚持惩防并举，在惩罚方面应当注意网络直播聚合共同犯罪认定规则的变通适用，以及网络直播聚合犯罪立法扩张、司法限缩与严格执法之间的关系；在预防方面应当构建国家、社会两位一体的预防模式。