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921.
为解决现阶段燃气无线抄表系统数据采集中无线网络不稳定、路由协议复杂、自修复能力薄弱等问题,提出并设计了一种基于cc1101无线传送模块的树形拓扑结构无线自组网系统。系统中主要对数据采集层路由协议和硬件实现进行了研究和设计,分析了该燃气无线抄表系统与传统燃气无线抄表系统的不同之处,设计了该系统数据采集层网络传输协议和总体结构。无线节点建在穿透力强的433 MHz的频率下进行通信,保证了系统自组网的稳定快速。  相似文献   
922.
The vast majority of research on the relationship between corporate governance and strategic management focuses on the impact of corporate governance on strategic management. In this article we propose a cyclical model, highlighting that strategic decisions can also affect corporate governance through shaping firm ownership structure. We discuss the impacts of strategic decisions on firm ownership structure and corporate governance in the contexts of publicly traded firms, private firms, and the privatization of state-owned enterprises. We hope that our cyclical model can promote researchers to develop a more complete view about the relationships between strategic management, ownership structure, and corporate governance.  相似文献   
923.
Monk parakeets (Myiopsitta monachus) are the most abundant and widely distributed of the naturalized parrots in the United States. Their presence is simultaneously encouraged by some humans (through use of bird feeders) and discouraged by others (through removal of their nests) and, as a result, they show an interesting spatial distribution across urban areas. We used an online public survey and field surveys to examine the influence of human activities and land use on the distribution of this exotic species around Chicago, IL (USA). These efforts resulted in detection of 249 nesting structures and approximately 778 birds across the region. A CART analysis successfully separated nesting sites from random sites and correctly classified 90?% of the nesting sites. The most important factor in the model was land use, with nests typically found in areas with less than 84?% residential zoning. We found nests on a wide variety of substrates including trees, cell phone towers, and stadium lights. Spatial point pattern analysis indicated that nests in trees and nests in built substrates were significantly dissociated with each other at all scales. Nests on built substrates were closer to railroads and highways or in areas with lower human population density, suggesting either a difference in substrate availability or human tolerance between these settings. While humans may have a positive effect on distribution of monk parakeets at large spatial scales, at the scale of this study we see a potentially negative effect of too many humans on the distribution of monk parakeet nests.  相似文献   
924.
受政治、经济和文化等因素的深刻影响,处于乡村社会之中的民间信仰体系经历着两次较大规模的由断到续的过程。这个过程在很大程度上反映的是新中国成立60多年来中国民众宗教生活的状态,是一部新中国成立以来的民众宗教生活史。该研究集中对此两次“未预结局”现象进行讨论,通过其在一个壮族社区生活场景中的具体呈现,以展示出前后两次断裂与重拾的实际状况,尽力寻找这些现象背后的社会力量,以及这种力量与当地人社会生活之间的紧密关系。  相似文献   
925.
One of the standard variable selection procedures in multiple linear regression is to use a penalisation technique in least‐squares (LS) analysis. In this setting, many different types of penalties have been introduced to achieve variable selection. It is well known that LS analysis is sensitive to outliers, and consequently outliers can present serious problems for the classical variable selection procedures. Since rank‐based procedures have desirable robustness properties compared to LS procedures, we propose a rank‐based adaptive lasso‐type penalised regression estimator and a corresponding variable selection procedure for linear regression models. The proposed estimator and variable selection procedure are robust against outliers in both response and predictor space. Furthermore, since rank regression can yield unstable estimators in the presence of multicollinearity, in order to provide inference that is robust against multicollinearity, we adjust the penalty term in the adaptive lasso function by incorporating the standard errors of the rank estimator. The theoretical properties of the proposed procedures are established and their performances are investigated by means of simulations. Finally, the estimator and variable selection procedure are applied to the Plasma Beta‐Carotene Level data set.  相似文献   
926.
目前扣除系数的计算方法主要为分析法与模拟法,扣除系数的常见影响因素有客货列车速度比、区段均衡度、追踪间隔时分等。通过模拟法进行不同客货列车速度比下的运行图铺画,得出客货列车速度比对扣除系数的影响规律分析。实验表明:随着客货速度比的增加,扣除系数将逐渐变大,据此建议在相关双线客货混跑区段,选取合适的客货速度比,以减小对运行图通过能力的影响  相似文献   
927.
This paper investigates the gender wage gap for full-time formal sector employees, disaggregated by education level. The gap between the labor force participation rate of women with tertiary education and those with lower levels of education is substantial. There is no such gap for men. Hence, existing gender wage gap studies for Turkey, where we observe lopsided labor force participation rates by education levels, compare two very different populations. We disaggregate the whole sample by education level to create more homogenous sub-groups. For Turkey, without disaggregation, the gender wage gap was 13% in 2011, and women are significantly over-qualified relative to men on observed characteristics. Once we disaggregate the sample by education level, we show that the gender wage gap is 24% for less educated women and 9% for women with tertiary education in full-time formal employment. Observed characteristics only explain 1 % of this gap in absolute terms. We further disaggregate the data by public and private employment. The gender gap is higher in the private sector. However, women with tertiary education in the public sector are significantly better qualified compared to men, and consequently the adjusted gender wage gap is higher for women with tertiary education in the public sector. Our estimates also indicate a rise in the gender wage gap between 2004 and 2011.  相似文献   
928.
In England, placement within the looked after system is not viewed as a desirable long‐term solution for most children, and policy has prioritised continued contact with parents, and swift return home, wherever possible. This review examines policy approaches to work with families of looked after children in England and in three other European countries: Denmark, France and the Netherlands, aiming to identify areas for shared learning in relation to this challenging area of policy and practice. The research highlights relationships between care populations and policy understandings of the purpose of work with families, including understandings of children's and/or parents’ rights.  相似文献   
929.
皖北地区旅游业是安徽省旅游业发展的短板,要实现皖北旅游业快速发展就要深究皖北旅游业发展缓慢的症结所在。本文选取淮北市作为调查点,从主客观方面分析了制约淮北市旅游业发展的因素并提出解决对策,以此为皖北旅游业发展提供借鉴。  相似文献   
930.
Starting in the 2000s, Denmark and Norway have undergone extensive restructuring of their health-related social benefit programmes, including how they are governed. Several reforms have sought to enhance inter-sectoral collaboration. Aiming at ensuring patients’ faster return to work, policy-makers have instituted economic incentives to both individuals and the health and welfare organisations who handle them. Through an institutional logics approach, this paper explores how hospital social workers in these countries are experiencing these changes. The ‘social’ part of post-treatment care and rehabilitation receives more attention in the Norwegian institutional set-up than in the Danish, and whilst challenges are experienced in both countries, in group interviews Danish social workers in particular express concerns about the implications of the accelerated return-to-work focus. In both countries, they report increasing difficulties in ‘making their way through’ the state-municipal bureaucracy. However, by drawing on the formal health knowledge derived from medical settings and the symbolic capital it bestows on them, they often manage to negotiate the work-and-welfare services, thereby transforming the social context for the patients.  相似文献   
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