Bounding the inefficiency of logit-based stochastic user equilibrium

Bounding the inefficiency of selfish routing has become an emerging research subject. A central result obtained in the literature is that the inefficiency of deterministic User Equilibrium (UE) is bounded and the bound is independent of network topology. This paper makes a contribution to the literature by bounding the inefficiency of the logit-based Stochastic User Equilibrium (SUE). In a stochastic environment there are two different definitions of system optimization: one is the traditional System Optimum (SO) which minimizes the total actual system travel time, and the other is the Stochastic System Optimum (SSO) which minimizes the total perceived travel time of all users. Thus there are two ways to define the inefficiency of SUE, i.e. to compare SUE with SO in terms of total actual system travel time, or to compare SUE with SSO in terms of total perceived travel time. We establish upper bounds on the inefficiency of SUE in both situations

Weakly Secure Symmetric Multilevel Diversity Coding

Multilevel diversity coding is a classical coding model where multiple mutually independent information messages are encoded, such that different reliability requirements can be afforded to different messages. It is well known that {\em superposition coding}, namely separately encoding the independent messages, is optimal for symmetric multilevel diversity coding (SMDC) (Yeung-Zhang 1999). In the current paper, we consider weakly secure SMDC where security constraints are injected on each individual message, and provide a complete characterization of the conditions under which superposition coding is sum-rate optimal. Two joint coding strategies, which lead to rate savings compared to superposition coding, are proposed, where some coding components for one message can be used as the encryption key for another. By applying different variants of Han's inequality, we show that the lack of opportunity to apply these two coding strategies directly implies the optimality of superposition coding. It is further shown that under a set of particular security constraints, one of the proposed joint coding strategies can be used to construct a code that achieves the optimal rate region.Comment: The paper has been accepted by IEEE Transactions on Information Theor

Probe system design for three dimensional micro/nano scratching machine

This paper presents the design and testing methodologies for a probe system used in a tip-based three dimensional micro/nano scratching machine. The probe system is one of the most important components of the scratching machine, including an electromagnetic device and a probe suspension mechanism. The electromagnetic device is used to generate electromagnetic force to drive the probe suspension mechanism, and further scratch the sample. The probe suspension mechanism is utilized to support the diamond probe and form the capacitor plates with the aluminum film. Both analytical modeling and finite element analysis are conducted to improve the static and dynamic characteristics of the proposed scratching machine. A prototype has been developed to validate the established design methodologies. A number of experimental tests have been conducted to examine the prototype performance. From the experimental results, it is noted that the developed probe system has a force resolution of 78.4 μN, a displacement resolution of 60 nm, and the first natural frequency of 465 Hz. This indicates that it can be used for the development of the three dimensional submicron or even nano scratching

Systematic Longitudinal Evaluating on boosting preschool children’s food literacy

To evaluate different methods in lifting food literacy which are applied to preschool children. Most articles are based on cross-sectional studies, an observational longitudinal design is seldom used, making it difficult to identify the true effectiveness of the methods. Thus, this article use a longitudinal method, including several online database. A systematic article based on longitudinal researches, by searching data in four electronic databases, Web of Science, PubMed, Elsevier (Science Direct) and Google Scholar, setting eligibility criteria, data selection, extracting data, data synthesis and quality assessment. Study identifies 771 original data, and after the de-duplication and eligibility selection, 9 studies are included in the article. Despite the small amount of literature applied, evidences are quiet useful. In comparison of caregiver-based intervention and classroom-based intervention, the later shows more effectiveness in short-term awareness training. Also, great potential has been found in technology-based intervention. The authors recommend future studies to focus on longitudinal research, so as to assess the potential of early childhood food literacy intervention, the mechanism and methods of these studies, the duration and effectiveness in different followup time etc

Design and control methodology of a 3-DOF flexure-based mechanism for micro/nano-positioning

A 3-DOF (X–Y–θZ) planar flexure-based mechanism is designed and monolithically manufactured using Wire Electro-Discharge Machining (WEDM) technology. The compact flexure-based mechanism is directly driven by three piezoelectric actuators (PZTs) through decoupling mechanisms. The orthogonal configuration in the x and y directions can guarantee the decoupling translational motion in these axes. The rotational motion and translational displacement in the x direction can be decoupled by controlling the piezoelectric actuators in the x axis with the same displacement values in same and opposite motion directions, respectively. The static and dynamic models of the developed flexure-based mechanism have been developed based on the pseudo-rigid-body model methodology. The mechanical design optimization is conducted to improve the static and dynamic characteristics of the flexure-based mechanism. Finite Element Analyses (FEA) are also carried out to verify the established models and optimization results. A novel hybrid feedforward/feedback controller has been provided to eliminate/reduce the nonlinear hysteresis and external disturbance of the flexure-based mechanism. Experimental testing has been performed to examine the dynamic performance of the developed flexure-based mechanism