Employees’ opportunities,preferences, and practices in telecommuting adoption

This study uses three separate models for the opportunity, preference, and practice of telecommuting to analyze employee telecommuting adoption. Explanatory clusters relate to organizational, job, household, and individual characteristics derived from the combined insights from literature on telework management and employees’ telecommuting decisions and behavior. Data was collected from 849 employees using a personal computer at the workplace, selected from a representative sample of the Dutch labor force. Multivariate analyses were applied. Opportunity largely depended on organizational and job characteristics. Preference was dependent on all explanatory clusters. Practice was especially dependent on job and individual characteristics.     

Glacier changes in Glacier Bay,Alaska, during 2000–2012

This article presents measurements of glacier surface areas, mean snow line altitude (MSLA) values, mean snow accumulation area ratio (MAAR) values, and elevation changes in the Glacier Bay, Alaska, using Landsat Thematic Mapper (TM)/Landsat Enhanced Thematic Mapper Plus (ETM+) images and digital elevation models (DEMs) from Shuttle Radar Topography Mission (SRTM) and interferometric synthetic aperture radar (IFSAR) data during 2000–2012. Glacier area estimation results showed that Desolation glacier and Fairweather glacier have lost 2.6% and 2.2% of the glacier area, respectively. Only minor surface area changes were seen in Cascade glacier, Crillon glacier, and Lituya glacier during the study period. The results of MSLA and MAAR showed that the MSLA of Fairweather glacier, Lituya glacier, and Desolation glacier increased by about 120–289 m and the MAAR of Fairweather glacier, Lituya glacier, and Desolation glacier decreased by about 3–6%. In contrast, MSLA and MAAR of Crillon glacier decreased by about 70 m and increased by about 1%, respectively. Glacier elevation change results showed that 7.7 m, 4.6 m and 1.5 m of mean thinning change were observed, respectively, on Fairweather glacier, Lituya glacier, and Desolation glacier. However, 7 m and 0.65 m of mean thickening were, respectively, experienced on Cascade glacier and Crillon glacier in the same period. Results from the study indicated that glacier retreat (Fairweather glacier, Lituya glacier, and Desolation glacier) affected by higher temperatures probably dominates with over-increased precipitation. However, increasing debris cover on the glacier surface can also modify the glacier dynamic, resulting in a different response to global warming.     

ADRC in output and error form: connection, equivalence, performance

In this work, we investigate two specific linear ADRC structures, namely output- and error-based. The former is considered a “standard” version of ADRC, a title obtained primarily thanks to its simplicity and effectiveness, which have spurred its adoption across multiple industries. The latter is found to be especially appealing to practitioners as its feedback error-driven structure bares similarities to conventional control solutions, like PI and PID. In this paper, we describe newly found connections between the two considered ADRC structures, which allowed us to formally establish conditions for their equivalence. Furthermore, the conducted comprehensive performance comparison between output- and error-based ADRCs has facilitated the identification of specific modules within them, which can now be conveniently used as building blocks, thus aiding the control designers in customizing ADRC-based solutions and making them most suitable for their applications.     

On the notions of normality, locality, and operational stability in ADRC

Treating plant dynamics as an ideal integrator chain disturbed by the total disturbance is the hallmark of active disturbance rejection control (ADRC). To interpret its effectiveness and success, to explain why so many vastly different dynamic systems can be treated in this manner, and to answer why a detailed, accurate, and global mathematical model is unnecessary, is the target of this paper. Driven by a motivating example, the notions of normality and locality are introduced. Normality shows that, in ADRC, the plant is normalized to an integrator chain, which is called local nominal model and locally describes the plant’s frequency response in the neighborhood of the expected gain crossover frequency. Locality interprets why ADRC can design the controller only with the local information of the plant. With normality and locality, ADRC can be effective and robust, and obtain operational stability discussed by T. S. Tsien. Then viewing proportional-integral-derivative (PID) control as a low-frequency approximation of second-order linear ADRC, the above results are extended to PID control. A controller design framework is proposed to obtain the controller in three steps: (1) choose an integrator chain as the local nominal model of the plant; (2) select a controller family corresponding to the local nominal model; and (3) tune the controller to guarantee the gain crossover frequency specification. The second-order linear ADRC and the PID control are two special cases of the framework.     

中国科技股龙头,“Made in清华”

北京清华大学在中国学术界具有无可替代的地位。它的校办企业——清华同方,借着清华大学技术、人才优势,在中国高等学府校办企业中,表现也是一流。     

M-learning in review： Technology, standard and evaluation

Nowadays E-learning as a form of learning depending on networks and computer devices has been expanding by leaps and bounds. As a special kind of E-learning, M-learning （mobile learning） aims at the use of mobile devices anywhere at anytime by anybody. In this paper, the technologies to develop a M-learning system are deeply analyzed according to the layer model at first. Then, from the view of application, the standardization in M-learning is researched in order to accelerate the development and popularization of M-learning. Finally, quality estimation of M-learning system is discussed from the view of QoE （quality of experiences）. The experience form end-user is the sole effective norm to judge the result of M-learning technology. It is no doubt that technologies, standardization and evaluation will play very important parts in the course of M-leaming development.     

IPv6,我最in的校园专网

几年前,当人们意识到现有TCP/IP协议存在的诸多问题的时候,一个新版本的TCP/IP协议被提出,被称为IPv6(Internet Protocol Version6)。在未来若干年IPv4将逐渐被IPv6取代,在中国,这一切正悄然发生在大学中……新生:学长,听说IPv6不错,下载和看网络电视速度飞快,这个网和原来我们用的有什么区别啊?快教教我怎么用吧!学长:我先跟你说说什么是IPv6。由于协议版本的转换,IPv6需要对网络改建或者新建,所以速度会有很大提升。现在IPv6还处于实验性建设时期,部分大学和科研单位开通IPv6网络。IPv6将一百多所大学的网络资源免费整合到一起,而且传输速度一点都不比原来校内网络慢。当然,IPv6不仅仅是为了资源共享,网络电视、视频点播都是大学生非常喜爱的应用。     

in the Late Jurassic, especially the huge volume

stage, the collapse arose when the transitional magma chamber was emptied. Subvolcanic rooks intruded along the collapsed ring faults. The volcanic complex is mainly composed of fragmentizing phenocrystic rhyolites.The volcanic activities began with the acid, with the high     

DInSAR investigation in the Pärvie end-glacial fault region,Lapland, Sweden

Northern Fennoscandia bears witness to the Pleistocene glaciation in the form of a series of large faults that have been shown to have ruptured immediately after the retreat of the ice sheet, about 9500 years ago. The largest one, known as the Pärvie fault, consists of a 155 km long linear series of fault scarps forming north–northeast-trending, that stretch west of Kiruna, Lapland. End-glacial intra-plate faults of this extent are very rare in the continental crust and the Pärvie system represents one of the major fault zone structures of this type in the world. Seismological evidence shows that there is still noticeable seismic activity, roughly one event of magnitude 2 per year that can be attributed to the fault. Nevertheless assessing its state of activity is a difficult task due to the extent and remoteness of the area. This study is aimed at the determination of crustal motion around the Pärvie fault zone using the differential inter-ferometric synthetic aperture radar (DInSAR) technique, based on images acquired with the European Space Agency (ESA) satellites European Remote Sensing (ERS) 1, ERS-2, and the Environmental Satellite (ENVISAT). We present results achieved in terms of deformation of the crystalline bedrock along different sectors of the fault where high levels of coherence were obtained, even from image pairs several years apart. This finding does not exclude deformation in other segments, as observing conditions are not always as favourable in terms of data availability.     

Structural entropy,information potential,information balance and evolution in self-organizing systems†

This paper is the continuation of a preceding one which appeared in this journal, and presented an approach to self-organizing systems based upon information theory. To begin with, some illustrating examples try to show why one can think that the concept of information should play a crucial role in a theory of general systems. Then the concept of ‘ structural entropy ’, and the ‘ evolution principle ’ that we have previously introduced, are improved here in a definitive form. The concept of ‘ information potential ’ is defined and we show that the capacity of an information source is given by the logarithm of its inverse entropy rather than by its negative entropy. Composition laws for the structural entropy are stated and it is shown that these concepts provide an approach to information balance. Some simple examples are outlined to connect this approach with well known existing results.     

Open source software licenses: Strong-copyleft, non-copyleft, or somewhere in between?

Studies on open source software (OSS) have shown that the license under which an OSS is released has an impact on the success or failure of the software. In this paper, we model the relationship between an OSS developer's utility, the effort that goes into developing an OSS, his attitude towards the freedom to choose an OSS license, and the choice of OSS license. We find that the larger the effort to develop OSS, the more is the likelihood that the OSS license would be free from restrictions. Interestingly, the result holds even when all OSS developers prefer restrictive licenses or less-restrictive license. The results suggest that least-restrictive or non-copyleft license will dominate other types of OSS license when a large effort is required to develop derivative software. On the other hand, most-restrictive or strong-copyleft licenses will be the dominant license when minimal effort is required to develop the original OSS and the derivative software.