养鱼高产的稻田水稻减产原因与对策探讨

试验研究及大面积调查一致表明:鲜鱼亩产20～150kg,鲜鱼产出量与稻谷增产率呈极显著线性负相关关系,y=11.375～0.1543x,r=-0.9951;结果还表明,有效穗不足是养鱼高产的稻田水稻减产的实质性原因。为此初步提出了相应对策。     

学业自我概念的建构研究述评

学业自我概念是指个体在学业情境中形成的对自己在学业发展方面的比较稳定的认知、体验和评价。学业自我概念的建构一直是研究者广泛关注的一个重要研究方向。目前,交互影响模型、大鱼小池效应、内/外参照模型及其相关整合模型是学业自我概念建构的主要理论模型,揭示了比较方式对学业自我概念建构的重要影响性。在未来的研究中要加强对学业自我概念建构的跨文化研究、加强不同比较方式之间的整合研究、改善学业自我概念的建构研究范式。     

随机多址信道冲突分解算法及吞吐量分析

讨论了一种改进的随机多址信道二叉树形、三叉树形冲突分解算法，导出了分解冲突所需平均时隙数的解析表达式。获得了较高的分解效率，并将其结果应用于阻塞接入信道的计算机仿真实验，数值分析表明，可获得较高的系统稳定最大吞吐量。     

Identifiable state‐space models: A case study of the Bay of Fundy sea scallop fishery

State‐space models (SSMs) are now popular tools in fisheries science for providing management advice when faced with noisy survey and commercial fishery data. Such models are often fitted within a Bayesian framework requiring both the specification of prior distributions for model parameters and simulation‐based approaches for inference. Here we present a frequentist framework as a viable alternative and recommend using the Laplace approximation with automatic differentiation, as implemented in the R package Template Model Builder, for fast fitting and reliable inference. Additionally we highlight some identifiability issues associated with SSMs that fisheries scientists should be aware of and demonstrate how our modelling strategy surmounts these problems. Using the Bay of Fundy sea scallop fishery we show that our implementation yields more conservative advice than that of the reference model. The Canadian Journal of Statistics 47: 27–45; 2019 © 2018 Statistical Society of Canada     

万维网的小世界效应探讨

在工程信息的长期安全保存和可靠调用过程中，存在着信息和其使用系统之间的兼容问题和对信息定期检查、移存、转化的时间和效率问题。目前国内外对这两类问题还没有可行的解决方法和技术。介绍了“六度分离”现象和经典的小世界网络模型，提出了WWW模型的架构，并在此基础上提出了万维网中任意两个网页间链接路径的搜索算法和计算万维网的特征路径长度，借此验证万维网具有小世界效应，为解决大量级和分散性信息的管理问题提供了可靠的科学依据。     

Using a Web‐Based Diary Method to Estimate Risks and Benefits from Fish Consumption

Accurate estimates of the amount and type of fish people eat are necessary to determine the health benefits and risks of consuming fish, and to assess compliance with fish consumption guidelines issued for fish affected by chemical contaminants. We developed a web‐based and mobile‐phone‐enabled diary methodology to collect detailed fish consumption information for two 16‐week periods in the summers of 2014 and 2015. We recruited study participants from two populations living in the Great Lakes region—women of childbearing age (WCBA) and urban residents who had purchased fishing licenses. In this article, we describe the methodology in detail and provide evidence related to participation rates, the representativeness of our sample over time, and both convergent validity and reliability of the data collection methods. Overall, 56% of WCBA and 50% of urban anglers provided complete data across both data collection periods. Among those who provided information at the beginning of Year 2, 97% of both audiences provided information throughout the entire 16‐week period. Those who participated throughout the two‐year period were slightly older on average (1.9–2.5 years) than other members of our original samples. We conclude that using diaries with web and smartphone technology, combined with incentives and persistent communication, has strong potential for assessing fish consumption in other areas of the country or for situations where the potential risks associated with fish consumption are substantial and the cost can be justified.     

Translating privacy: developer cultures in the global world of practice

ABSTRACT

This paper makes the case for considering the role of cross-cultural encounters in shaping developers’ notions of information privacy. Recent studies on privacy by design shed light on developer practices yet tend to regard these workers as a generic category. The paper draws on two interviews with workers in a late-stage Israeli startup as a step toward localizing developers and the global products they design. The analysis identifies four narratives that juxtapose the local, the global and the commodification of users’ personal information: (1) the origin myth of the company; (2) workers’ personal and professional biographies; (3) reports on external regulations; and (4) accounts of work practices, rituals and communication formats. The analysis suggests how the globalization of the startup was implicated in changing ideas and practices relating to users’ information. The paper concludes by discussing some of the challenges facing a culturally-sensitive study of developers as mediators of privacy.     

Sparse matrices,and the estimation of variance components by likelihood methods

It is generally considered that analysis of variance by maximum likelihood or its variants is computationally impractical, despite existing techniques for reducing computational effect per iteration and for reducing the number of iterations to convergence. This paper shows thata major reduction in the overall computational effort can be achieved through the use of sparse-matrix algorithms that take advantage of the factorial designs that characterize most applications of large analysis-of-variance problems. In this paper, an algebraic structure for factorial designsis developed. Through this structure, it is shown that the required computations can be arranged so that sparse-matrix methods result in greatly reduced storage and time requirements.     

A genetic algorithm for assembly line balancing

Assembly line balancing is a very important aspect in any mass production setup. However, finding the optimal balance is a very difficult proposition because of the computational complexity involved. Hence sub-optimal solutions are preferred over optimal solutions. In this work, a genetic algorithm (GA) is presented for obtaining good quality solutions for assembly line balancing problems. A major feature of GA is the ability to take care of a variety of objective functions. A modified GA working with two populations, one of which allows infeasible solutions, and exchange of specimens at regular intervals is proposed for handling irregular search spaces. The experimental results obtained with a single population, as well as two populations are encouraging.     

Constructing 1-rotational NRDFs through an optimization approach: new (46,9,8), (51,10,9) and (55,9,8)-NRBDs

In this paper we formulate the problem of constructing 1-rotational near resolvable difference families as a combinatorial optimization problem where a global optimum corresponds to a desired difference family. Then, we develop an algorithm based on scatter search in conjunction with a tabu search to construct many of these difference families. In particular, we construct three new near resolvable difference families which lead to an equal number of new 1-rotational near resolvable block designs with parameters: (46,9,8), (51,10,9) and (55,9,8). Our results indicate that this conjunction outperforms both scatter search and tabu search.