Louis Kruh,Cryptologist, Editor,Activist

Abstract

The double transposition cipher was considered to be one of the most secure types of manual ciphers. It was extensively used in both World Wars and during the Cold War. In 1999, Otto Leiberich, the former head of the German federal office for information security, suggested that a double transposition challenge be published with specific parameters designed to ensure its security. Such a challenge was published by Klaus Schmeh in 2007. In November 2013, the authors solved the challenge using a ciphertext-only hill climbing attack. They also solved the challenge using a dictionary attack. In this article, they describe both methods, which are based on a “divide-and-conquer” approach. They additionally discuss the impact of their solutions with respect to the general security of the double transposition cipher.     

基于模糊PID参数自整定的细胞培养箱温度控制算法

针对细胞培养箱温度控制具有非线性、时滞性、易受干扰且难以建立精确的数学模型的特点,传统的PID控制方法对于快速维持系统箱内温度稳定存在一定的局限性。提出了以温度误差和误差变化率为控制输入,培养箱内温度为控制量的模糊PID参数自整定的温度控制算法,实现了对PID参数的实时在线修正。实验表明,该模糊PID参数自整定温度控制算法,温度从26℃上升到目标温度37℃,建立稳态的时间为2890s,温度超调极小。系统温度控制精度为±0.05℃,并在相同型号的细胞培养箱上同样得到验证。在控制稳定性方面获得了比传统PID控制更好的控温效果,稳定快,极小超调,温度控制精度高,能满足细胞培养箱温度控制的要求。     

Hyperbolic regression analysis for kinetics, electrophoresis, ELISA, RIA, Bradford, Lowry, and other applications

Hyperbolic regression analysis is an effective method for fitting experimental data points obtained from a variety of experiments in molecular biology, including enzyme kinetics, agarose gel electrophoresis of DNA fragments, SDS-polyacrylamide gel electrophoresis of proteins, enzyme-linked immunosorbent assays (ELISA), radioimmunoassays (RIA), Bradford protein quantitation assays, Lowry protein assays, and other applications. Hyperbolic regression yields excellent fitted curves without the biases that are introduced by carrying out linear regression on double reciprocal coordinates, and it produces one simple equation, encompassing all the data points, that can be used easily in a pocket calculator to estimate the values of unknown samples from the known standards.     

Pointcuts, advice, refinements, and collaborations: similarities, differences, and synergies

Aspect-oriented programming (AOP) is a novel programming paradigm that aims at modularizing complex software. It embraces several mechanisms including (1) pointcuts and advice as well as (2) refinements and collaborations. Though all these mechanisms deal with crosscutting concerns, i.e., a special class of design and implementation problems that challenge traditional programming paradigms, they do so in different ways. In this article we explore their relationship and their impact on modularity, which is an important prerequisite for reliable and maintainable software. Our exploration helps researchers and practitioners to understand their differences and exposes which mechanism is best used for which problem.     

Mandalas,screws, pears,and Klein bottles

The goal of this article is to present an informal introduction and tutorial on the production of aesthetically pleasing solid models. The article is intended for the nonmathematical reader interested in computer art. Simple generating formulas and recipes are included.     

Electronic Markets, Hierarchies, Hubs, and Intermediaries

The impact of information technologies on organizations is difficult to predict, although critical for developing comprehensive organizational strategies. Much of the difficulty is traceable to the treatment of all information technologies as a single factor, when in fact different technologies may have drastically different impacts on the organization. Specifically, the distinction between two general classes of technologies, communication and information processing technologies, is studied. An analytical model is developed to show that these two classes of technologies have exactly the opposite impacts on the organization. Moreover, the impact also depends on the organization, and its existing structure. Communication intensive and processing intensive organizational structures are distinguished and they are shown to be impacted differently by information technologies. An analytical framework is developed to show a continuum of organizational structures, depending on their relative communication and processing intensity, and the effect of various technologies is shown to be to move the organization along that continuum. Communication and information processing technologies are shown to move the organization in opposing directions. Finally, the analytical framework is shown to be robust and valid under a wide variety of conditions, covering most real life organizations.     

改进的三因素相互认证与密钥协商方案*

暴露在不安全公共网络中的医疗记录容易遭受到安全威胁和攻击,为了保护远程医疗信息系统中敏感的医疗数据,迫切需要一种安全高效的相互认证与密钥协商方案。针对Zhang等方案进行分析,发现此方案容易遭受内部特权攻击。为了修复上述安全漏洞,采用增强存储在智能卡中相关参数的安全性,以及使用混沌映射计算Diffie-Hellman问题等方式,提出了一种改进的三因素相互认证与密钥协商方案。所提方案在实现公共信道上敏感医疗数据保护的同时,提供了远程医疗诊断过程中的隐私保护特性。安全性分析表明所提方案不仅能够抵抗各类安全攻击,而且比已有的相关方案效率更高。     

Plagiarism, originality, assemblage

Although students work and live in a remix culture, composition pedagogy does not always value the discursive practices of that culture, especially when it comes to producing written work for academic contexts. The reasons for these views are historically determined and tied, at least in part, to relatively traditional notions of authorship and creativity. But “writers” in other contexts, both disciplinary and popular, have developed interesting and useful remix approaches that can aid invention, leverage intellectual and physical resources, and dramatize the social dimensions of composing in this day and age. These approaches, however, ask teachers to reconsider taken-for-granted assumptions about plagiarism and originality.     

Across disciplines: risk, design, method, process, and tools

In the search for solutions to make software development more predictable and controllable, one often looks for parallels in other disciplines such as architecture, bridge construction, and so on. The article looks at software development from the perspective of the electrical industry. Inspired by their management tradition, ATH techniek b.v. has learned to apply proven management techniques to software development. Simple and commonsense principles yield excellent results; for instance, developers reduced risk by estimating project effort using two different measures and by controlling execution. Comparing the software development processes with what goes on in the rest of the company or another application domain can be instructive     

Disjunctions, independence, refinements

An important question in constraint satisfaction is how to restrict the problem to ensure tractability (since the general problem is NP-hard). The use of disjunctions has proven to be a useful method for constructing tractable constraint classes from existing classes; the well-known ‘max-closed’ and ‘ORD-Horn’ constraints are examples of tractable classes that can be constructed this way. Three sufficient conditions (the guaranteed satisfaction property, 1-independence and 2-independence) that each ensure the tractability of constraints combined by disjunctions have been proposed in the literature. We show that these conditions are both necessary and sufficient for tractability in three different natural classes of disjunctive constraints. This suggests that deciding this kind of property is a very important task when dealing with disjunctive constraints. We provide a simple, automatic method for checking the 1-independence property—this method is applicable whenever the consistency of the constraints under consideration can be decided by path-consistency. Our method builds on a connection between independence and refinements (which is a way of reducing one constraint satisfaction problem to another.)