Similarity assessment of design behavior data

Understanding the cognitive aspects of design behavior is important in understanding the nature of design ability, and various studies are being conducted to understand the underlying cognitive aspects of design abilities and to develop methods to enhance them. While simple visualization supports in graphical forms are helpful in finding characteristics in protocol analysis, similarity assessment of the protocol data of various designers and various design tasks and situations will also help to understand designers and design problem characteristics. In this paper, we propose similarity assessment methods of design behavior data as support tools for understanding and analysis of the nature of design ability.     

Cognitive,social and teaching presence in a virtual world and a text chat

Using a framework of cognitive, social, and teaching presence, the nature of learning experiences in a three-dimensional virtual world environment (Second Life) and a text-chat learning environment without visuals (TeachNet) were investigated. A mixed method of code frequencies, coherence graphs, interviews, and a survey was used. The results revealed that the TeachNet debates included more cognitive presence codes that indicate higher levels of cognitive processing than in SL debates. The teams were significantly different from each other in the collaboration style for developing arguments and in the ways to use utterances associated with cognitive, social, and teaching presences, and the groups’ collaboration style became more established with more experience with the tasks. The three critical factors–tool, tasks and group cohesion–that affect cognitive, teaching, and social presence are discussed.     

Household Activity Pattern Problem with Autonomous Vehicles

Networks and Spatial Economics - The pace of changes in automating cars has sped up in the last few decades. Autonomous Vehicles (AVs) will dramatically change the future of transportation, and...     

A resource allocation policy for delay minimization in fetching capacitated feeds

As social media services such as Twitter and Facebook are gaining popularity, the amount of information published from those services is explosively growing. Most of them use feeds to facilitate distribution of a huge volume of content they publish. In this context, many users subscribe to feeds to acquire up-to-date information through feed aggregation services, and recent real-time search engines also increasingly utilize feeds to promptly find recent web content when it is produced. Accordingly, it is necessary for such services to effectively fetch feeds for minimizing fetching delay, while at the same time maximizing the number of fetched entries. Fetching delay is a time lag between entry publication and retrieval, which is primarily incurred by finiteness of fetching resources. In this paper, we consider a polling-based approach among the methods applicable to fetching feeds, which bases on a specific schedule for visiting feeds. While the existing polling-based approaches have focused on the allocation of fetching resources to feeds in order to either reduce the fetching delay or increase the number of fetched entries, we propose a resource allocation policy that can optimize both objectives. Extensive experiments have been carried out to evaluate the proposed model, in comparison with the existing alternative methods.     

H −/H ∞ sensor fault detection and isolation in linear time-invariant systems

This paper addresses sensor fault detection and isolation problems for continuous- and discrete-time linear time-invariant systems. To that end, we employ a bank consisting of the same number of observers as there are sensors. Both the observer gain and the residual gain are considered. Unlike earlier work, the design conditions with H _?/H _∞ performance are derived in terms of linear, rather than nonlinear, matrix inequalities. An illustrative example is provided to show the effectiveness of the proposed methodology.     

A satellite selection criterion incorporating the effect of elevation angle in GPS positioning

When positioning by global positioning systems, geometric dilution of precision is generally used as a satellite selection criterion. While it takes account of only geometric effects, there are other factors causing positioning error, such as ionospheric delay, tropospheric delay, and multipath. In this paper, a new criterion for satellite selection, which considers the effect of these errors, is proposed and the effectiveness of the proposed criterion is shown.     

Strain-rate effect on high temperature low-cycle fatigue deformation of AISI 304L stainless steel

The effect of strain rate on the behaviour of high temperature low-cycle fatigue is investigated for AISI 304L stainless steel. Regardless of the test temperature of 873 or 973 K, the fatigue life is saturated in the strain-rate range of slower than 4 × 10^–3 sec^–1. Also it is interesting to note that serrated flow, which is evidence of the occurrence of dynamic strain ageing, is clearly observed in the load-elongation hysteresis loops for strain rates that are slower (at 873 K) and faster (at 973 K) than 4 × 10^–3 sec^–1. Since the combination of temperature and strain rate is concerned with the phenomenon of dynamic strain ageing, it is considered that the above-mentioned saturated fatigue life at 873 K is caused by dynamic strain ageing and that the hardening effect due to dynamic strain ageing abnormally increases the fatigue life. However, even though the behaviour of fatigue life under strain rates slower than 4 × 10^–3 sec^–1 at 973 K has nothing to do with the dynamic strain ageing, it has been found that the failure life is also saturated in this slower strain-rate range. This behaviour is considered to be caused by the effect of creep, because the deformation under the low strain-rate activates the recovery process and as a result it causes saturation of the inelastic strain range.     

Synthesis and structural properties of lithium titanium oxide powder as-synthesized by two step calcination process

A two-step calcination synthesis, considering the potential for mass production, of lithium titanium oxide powder was carried out to fabricate a single Li₄Ti₅O₁₂ phase, which is useful for anode electrode material of Li-based rechargeable battery as well as an electrode for supercapacitor. The final composition is controlled by adding more TiO₂ powder into powder gained at one calcination process during the two calcination process. We investigated the influence of excess TiO₂ on the structural characteristics of lithium titanium oxide synthesized by the two-step calcination method. X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR) measurements showed that the as-synthesized powder had a spinel crystal structure as well as A composition of 4: 5: 12. In addition, a high resolution transmission electron microscopy (HRTEM) analysis revealed that the fabricated powder exhibited a single crystalline phase formation. These results indicated that the powder synthesized in the one-step calcination process showed coexistence crystalline phases, which are the Li₄Ti₅O₁₂ and Li_2.39Ti_3.4O₈ phase. However, in the two-step calcination process, the powder synthesized showed the single crystalline Li₄Ti₅O₁₂ phase. A very uniform grain size of the as-synthesized powder was shown in a field emission scanning electron microscopy (FESEM). These results suggested that the two-step calcination process can be used for synthesis of single crystalline Li₄Ti₅O₁₂ powder with uniform grain shape and provide motivation to pursue mass production of lithium titanium based oxide powder for bulk type batteries.