Realization of a Scalable and Reliable Multicast Transport Protocol for Many‐to‐Many Sessions

In this paper, we present the Enhanced Communication Transport Protocol–Part 5 (ECTP‐5), which provides scalable and reliable multicast communication service for many‐to‐many applications by constructing high quality recovery trees from two‐layer logical trees and repairing the losses via unicast automatic repeat request–based error control. In order to realize the protocol, we developed feasible protocol architectures and building blocks including additional functions which deal with engineering details, such as membership dynamics and sender coordination. Experimental results show that ECTP‐5 scales well with various session sizes and packet loss rates in terms of control overhead and recovery latency.     

Is Usage a Missing Link in Explaining the Perceived Learning Outcome of Technology-Mediated Learning?

Information systems (IS) researchers have demonstrated that usage is a key variable in explaining the performance impact of information technology. However, existing technology-mediated learning (TML) studies have not examined the influence of usage on learning outcome and the factors that determine the usage of TML. To address this research gap, our study presents and tests a TML model by drawing insights from two research streams. First, following the IS literature, we incorporate the impact of technology usage on individual performance. Second, building on the social cognitive theory, we study the influences of self-efficacy beliefs (system and subject domain) and affective responses (affect and anxiety) on technology usage. Based on 503 matched responses collected using two-stage questionnaire surveys, our analyses confirm the significance of usage in mediating the effects of system self-efficacy and anxiety on perceived learning outcome, but not in mediating the effects of affect and subject-domain self-efficacy. We find strong support for the influences of self-efficacy beliefs on affective responses. Self-efficacy beliefs of the users are also observed to change over time and perceived learning outcome plays a significant role in explaining this change. Our research enhances the existing TML theory by producing useful insights regarding the influence of social cognitive factors of learners on the usage of TML and how usage mediates the influence of these variables on perceived learning outcome.     

T–S Model-Based SMC Reliable Design for a Class of Nonlinear Control Systems

This paper studies the robust reliable control issues based on the Takagi–Sugeno (T–S) fuzzy system modeling method and the sliding-mode control (SMC) technique. The combined scheme is shown to have the merits of both approaches. It not only alleviates the online computational burden by using the T–S fuzzy model to implement the original nonlinear system (since most of the system parameters of the T–S model can be offline computed) but also preserves the advantages of the SMC schemes, including rapid response and robustness. Moreover, the combined scheme does not require online computation of any nonlinear term of the original dynamics, and the increase in the partition number of the region of premise variables does not create extra online computational burdens for the scheme. Under the design, the control mission can continue safely without prompt external support, even when some of the actuators fail to operate. Meanwhile, both the active and the passive reliable designs are presented. The proposed analytical results are also applied to the attitude control of a spacecraft. Simulation results demonstrate the benefits of the proposed scheme.      

Surface Reconstruction for Free-Space 360 ° Fluorescence Molecular Tomography and the Effects of Animal Motion

Complete projection (360deg) free-space fluorescence tomography of opaque media is poised to enable 3-D imaging through entire small animals in vivo with improved depth resolution compared to 360deg-projection fiber-based systems or limited-view angle systems. This approach can lead to a new generation of fluorescence molecular tomography (FMT) performance since it allows high spatial sampling of photon fields propagating through tissue at any projection, employing nonconstricted animal surfaces. Herein, we employ a volume carving method to capture 3-D surfaces of diffusive objects and register the captured surface in the geometry of an FMT 360deg-projection acquisition system to obtain 3-D fluorescence image reconstructions. Using experimental measurements we evaluate the accuracy of the surface capture procedure by reconstructing the surfaces of phantoms of known dimensions. We then employ this methodology to characterize the animal movement of anaesthetized animals. We find that the effects of animal movement on the FMT reconstructed image were within system resolution limits (~0.07 cm).     

A novel Hα control strategy for design of a robust dynamic routing algorithm in traffic networks

In this paper novel centralized and decentralized routing control strategies based on minimization of the worst-case queuing length are proposed. The centralized routing problem is formulated as an H_infin optimal control problem to achieve a robust routing performance in presence of multiple and unknown fast time-varying network delays. Unlike similar previous work in the literature the delays in the queuing model are assumed to be unknown and time-varying. A Linear Matrix Inequality (LMI) constraint is obtained to design a delay-dependent H_infin controller. The physical constraints that are present in the network are then expressed as LMI feasibility conditions. Our proposed centralized routing scheme is then reformulated in a decentralized frame work. This modification yields an algorithm that obtains the "fastest route", increases the robustness against multiple unknown time-varying delays, and enhances the scalability of the algorithm to large scale traffic networks. Simulation results are presented to illustrate and demonstrate the effectiveness and capabilities of our proposed novel dynamic routing strategies.     

Synthesis and Structure–Property Relations of a Series of Photochromic Molecular Glasses for Controlled and Efficient Formation of Surface Relief Nanostructures

This paper reports on the synthesis and properties of a new series of photochromic molecular glasses and their structure–property relations with respect to a controlled and efficient formation of surface relief nanostructures. The aim of the paper is to establish a correlation between molecular structure, optical susceptibility, and the achievable surface relief heights. The molecular glasses consist of a triphenylamine core and three azobenzene side groups attached via an ester linkage. Structural variations are performed with respect to the substitution at the azobenzene moiety in order to promote a formation of a stable amorphous phase and to tune absorption properties and molecular dynamics. Surface relief gratings (SRGs) and complex surface patterns can easily be inscribed via holographic techniques. The modulation heights are determined with an equation adapted from the theory for thin gratings, and the values are confirmed with AFM measurements. Temperature‐dependent holographic measurements allow for monitoring of SRG build‐up and decay and the stability at elevated temperatures, as well as determination of the glass transition temperature. SRG modulation heights of above 600 nm are achieved. These are the highest values reported for molecular glasses to date. The surface patterns of the molecular glasses are stable enough to be copied in a replica molding process. It is demonstrated that the replica can be used to transfer the surface pattern onto a common thermoplastic polymer.