Tencent and Facebook Data Validate Metcalfe’s Law

In 1980s, Robert Metcalfe, the inventor of Ethernet, proposed a formulation of network value in terms of the network size (the number of nodes of the network), which was later named as Metcalfe’s law. ...     

Zipf定律与网络信息计量学

作为文献计量学重要定律的Zipf定律已在许多领域得到较广泛的应用,网络信息计量学伴随着网络信息的激增而受到人们越来越大的关注。该文结合搜索结果数量的分布情况,提出了在网络信息计量学中仍然存在Zipf定律的猜想,并采用公开的词语集在几个代表性的搜索引擎中进行实验验证,证实了搜索结果数目近似服从Zipf定律的结论,其中Baidu与So搜索结果的Zipf指数为0.003。     

Discrete time sliding mode control with reduced switching – a new reaching law approach

In this paper, a novel reaching law for discrete‐time variable structure systems is proposed. It ensures that the representative point (state) of the controlled plant approaches the switching plane in finite time and then crosses it in every subsequent step. Moreover, the proposed reaching law ensures that for the nominal plant the absolute value of the sliding variable asymptotically decreases to zero, and for the perturbed plant, it converges to a smaller interval around zero than with the application of previously proposed reaching laws. The control method proposed in this paper guarantees asymptotic stability of the nominal system and uniform ultimate boundedness of the perturbed one. Furthermore, the method ensures that the sliding variable rate of change (i.e. the difference between its values at any two subsequent sampling instants) is bounded by design parameters, which do not depend on the system initial conditions. This is a highly desirable property, as it results in a priori specified, ‘almost’ constant convergence rate of the sliding variable when the system state is far off the switching plane and helps enforce state constraints in the system. Copyright © 2014 John Wiley & Sons, Ltd.     

Rendering of HDR images to improve brightness discrimination

The impression of quality of images can be enhanced on a high dynamic range (HDR) displays. Generally, a conventional 8‐bit image can be processed to an HDR image by inverse tone mapping operators. Among the operators, brightness discrimination mapping by applying brightness adaptation model attempted to mimic the human visual system. In this paper, we use a brightness adaptation model to derive a brightness discrimination mapping algorithm for HDR displays. The proposed algorithm maximizes a function, which represents the local and global brightness discrimination range by exploiting characteristics of the human visual system. Enhancement of details is verified by visualizing HDR images from dark to bright regions. Improvement of dynamic range is quantified by measuring increased discrimination ratio.     

Proactive privacy for a driverless age

Autonomous vehicles are on the cusp of disrupting the entire transportation industry and current privacy legislation is not yet equipped to deal with the changes being spurred by this innovation. This paper enumerates and elucidates on the various privacy concerns that are specific autonomous vehicles. It also proposes the principles of “Privacy-by-Design”, an industry trend pertaining to other arenas of privacy, be adapted and used for regulating privacy around autonomous vehicles. It calls for the NHTSA (National Highway Transportation Safety Administration), with guidance from the FCC, and the FTC, to use their expertise in creating administrative rules that will protect the privacy of the public. Having learned valuable lessons from recent privacy concerns in the mobile device industry, the Privacy-by-Design approach would help ease the transition into this useful, but potentially intrusive technology. Currently, privacy is receiving significant attention in publications, but with autonomous vehicles being a nascent industry, there is very little being said about the privacy concerns specifically pertaining to these technology autonomous vehicles. Recent strides in the technology and the legislative acceptance of these vehicles have made them a widely discussed topic, and thus makes a thorough discussion of privacy related specifically to this technology both timely and relevant. This paper provides an early assessment of an area of concern that is growing as rapidly as are autonomous vehicles. The technology is being proven effective and safe, so the real focus will shift to use concerns, like privacy. The autonomous vehicle industry is still early in its development, and there is imminent opportunity to anchor privacy into the fundamentals of autonomous vehicles, preempting numerous potential infringements.     

Analysis of General Ideal Proportional Navigation Guidance Laws

In this work, the capture region of the general ideal proportional navigation guidance law is analyzed with the following constraints: (i) the target's input acceleration is subject to independent or magnitude saturation, and (ii) the missile's input acceleration is subject to magnitude saturation. In addition to the case of unbounded maneuverability of missile with or without knowing the target acceleration, the necessary and sufficient condition for a bounded maneuvering missile that captures a nonmaneuvering target is also derived. Furthermore, the conditions that result in zero impact velocity are discovered and discussed in some of the cases. The capture regions that cannot be obtained analytically are determined numerically by a powerful classifier, the least square support vector machines. To have the capture region ready for least square support vector machines, all the state variables are transformed into modified polar variables and non‐dimensionalized to reduce the number of independent variables. In order to make the implementation possible in real time, an approximation of the Gaussian radial basis function is adopted to obtain the corresponding nonlinear feature mapping function. Through numerous numerical experiments, the proposed technique is found to be adequate for storing the capture region in an onboard fire control computer.     

Exploring and modeling unimanual object manipulation on multi-touch displays

Touch-sensitive devices are becoming increasingly wide-spread, and consequently gestural interfaces have become familiar to the public. Despite the fact that many gestures require frequently dragging, pinching, spreading, and rotating the finger-tips, there currently does not exist a human performance model describing this interaction. In this paper, a novel user performance model is derived for virtual object manipulation on touch-sensitive displays, which involves simultaneous translation, rotation, and scaling of the object. Two controlled experiments with dual-finger unimanual manipulations were conducted to validate the new model. The results indicate that the model fits the experimental data well (with R² and R values above 0.9), and performs the best among several alternative models. Moreover, based on the analysis of the empirical data, the simultaneity nature of manipulation in the task is explored and several design implications are provided.     

压力和温度对瓦斯扩散规律的影响研究

针对瓦斯吸附解吸法测定瓦斯扩散系数时局限于颗粒煤、无法施加围压且气体压力不能任意设定等问题,采用规则块煤结合气相色谱分析法测定瓦斯在块煤中的扩散系数,分析了不同气体压力、温度下块煤瓦斯扩散规律。实验结果表明,随着气体压力的增大,煤基质吸附气体增加且发生膨胀变形,从而孔隙减小,扩散阻力增大,扩散系数减小;随着温度的升高,气体分子运动速度增大,扩散动力增强,扩散系数变大。     

Territorial targeting in EU private law

In a series of rulings given in the last few years, the Court of Justice of the European Union (EU) has made use of the concept of targeting by a trader of a particular territorial market as a device for determining the scope of European legislation on private law. The concept is of particular importance in the context of trading activities conducted by means of the Internet, though its significance is not confined to such activities. In particular, the European Court has used the concept of targeting for the purpose of restricting the substantive ambit of intellectual property rights created or harmonised by EU legislation. On the other hand, it has avoided use of the concept of targeting in the context of EU legislation allocating jurisdiction between the courts of the Member States, even in respect of disputes involving intellectual property, except where a legislative text specifically invokes such a concept. The instant paper endeavours to review the position as currently established by the European case-law, and to predict the likely further developments.     

基于小波分析的断面污染负荷演变 规律研究初探 ——以松花江哈尔滨段为例

采用Morlet小波函数对松花江哈尔滨水源地站1999 } 2008年逐月断面污染物负荷量变化过程进行小波分析,以多时间尺度揭示10年间污染物负荷量年际变化关系。结果表明,1年、2年、5 年时间尺度呈现强周期交替规律,3年、4年呈现弱周期交替规律。污染物负荷量年内变化与地表径流过程基本相符;受2005年松花江污染突发事件影响,该序列存在突变点。