As the use of wireless sensor networks (WSNs) becomes widespread, node density tends to increase. This poses a new challenge for medium access control (MAC) protocol design. Although traditional MAC protocols achieve low-power operation, they only single channel which limits their performance. Several multi-channel WSNs have been recently proposed. One key observations is that these are less energy efficient than single-channel under light traffic conditions. In this paper, we propose an...

Monitoring a user's mobility during daily life is an essential requirement in providing advanced mobile services. While extensive attempts have been made to monitor user mobility, previous work has rarely addressed issues with battery lifetime real deployment. In this paper, we introduce SmartDC, prediction-based adaptive duty cycling scheme provide contextual information about mobility: time-resolved places and paths. Unlike approaches that focused on minimizing energy consumption for...

Indoor pedestrian tracking extends location-based services to indoor environments. Typical positioning systems employ a training/positioning model using Wi-Fi fingerprints. While these approaches have practical results in terms of accuracy and coverage, they require an map, which is typically not available the average user involves significant training costs. A approach should consider environment without pretrained database or floor plan. In this paper, we present system, called SmartSLAM,...

A mobility model is an essential requirement in accurately predicting individual's future location. While extensive studies have been conducted to predict human mobility, previous work used coarse-grained data with limited ability capture movements at a fine-grained level. In this paper, we empirically analyze several models for temporal behavior of individual user. Unlike approaches, which employed partial temporal-coverage, use and continuous the evaluation models.We explore regularity...

The Wi-Fi fingerprinting (WF) technique normally suffers from the RSS (Received Signal Strength) variance problem caused by environmental changes that are inherent in both training and localization phases. Several calibration algorithms have been proposed but they only focus on hardware problem. Moreover, smartphones were not evaluated these now widely used WF systems. In this paper, we analyze various aspect of when using for WF: device type, placement, user direction, over time. To...

Abstract A multistage adaptive testing (MST) design was implemented for the Programme International Assessment of Adult Competencies (PIAAC) starting in 2012 about 40 countries and has been 2018 cycle Student (PISA) more than 80 countries. Using examples from PISA PIAAC, this article addresses advantages considerations an MST context international large‐scale assessments (ILSAs). It illustrates discusses unique features designs PIAAC expected gains test efficiency accuracy, as well...

Based on concerns about the item response theory (IRT) linking approach used in Programme for International Student Assessment (PISA) until 2012 as well desire to include new, more complex, interactive items with introduction of computer-based assessments, alternative IRT methods were implemented 2015 PISA round. The new method represents a concurrent calibration using all available data, enabling us find parameters that maximize fit across groups and allowing investigate measurement...

Abstract Careless and insufficient effort responding (C/IER) poses a major threat to the quality of large-scale survey data. Traditional indicator-based procedures for its detection are limited in that they only sensitive specific types C/IER behavior, such as straight lining or rapid responding, rely on arbitrary threshold settings, do not allow taking uncertainty classification into account. Overcoming these limitations, we develop two-step screen-time-based weighting procedure...

This paper presents the design principles, implementation, and evaluation of RETOS operating system which is specifically developed for micro sensor nodes. has four distinct objectives, are to provide (1) a multithreaded programming interface, (2) resiliency, (3) kernel extensibility with dynamic reconfiguration, (4) WSN-oriented network abstraction. system, hence it provides commonly used thread model interface developers. We have various implementation techniques optimize performance...

Monitoring a user's mobility during daily life is an essential requirement in providing advanced mobile services. While extensive attempts have been made to monitor user mobility, previous work has rarely addressed issues with predictions of temporal behavior real deployment. In this paper, we introduce SmartDC, prediction-based adaptive duty cycling scheme provide contextual information about mobility: time-resolved places and paths. Unlike approaches that focused on minimizing energy...

Modern mobile devices are equipped with multiple network interfaces, including 3G/LTE and WiFi. Bandwidth aggregation over LTE WiFi links offers an attractive opportunity of supporting bandwidth-intensive services, such as high-quality video streaming, on devices. However, achieving effective bandwidth in environments raises several challenges related to deployment, link heterogeneity, fluctuation, energy consumption. We present GreenBag, energy-efficient middleware that supports real-time...

In this study we extend and assess the trifactor model for multiple-ratings data in which two different raters give independent scores same responses (e.g., GRE essay or to subset of PISA constructed-responses). The was extended incorporate a cross-classified structure items raters) instead strictly hierarchical structure. present set simulations reflect incompleteness imbalance real-world assessments. effects rate missingness ignoring differences among are investigated using sets...

International large-scale assessments (ILSAs) transitioned from paper-based to computer-based (CBAs) facilitating the use of new item types and more effective data collection tools. This allows implementation complex test designs collect process response time (RT) data. These can be used improve quality accuracy scores obtained through latent regression (population) models. However, move a CBA also poses challenges for comparability trend measurement, one major goals in ISLAs. We provide an...

Abstract This study developed learning progression‐based measures of science teachers’ content knowledge (CK) and pedagogical (PCK). The focus on an important topic in secondary curriculum using scientific reasoning (i.e., tracing matter, energy, connecting scales) to explain plants gaining weight exchanging gases. Using a design‐based research approach, we conducted the four cycles. findings reported this article were based data collected last two cycles (year 2011–2012 year 2012–2013)....

The research presented in this article combines mathematical derivations and empirical results to investigate effects of the nonparametric anchoring vignette approach proposed by King, Murray, Salomon, Tandon on reliability validity rating data. aims correct data for response styles improve comparability across individuals groups. Vignettes are used adjust self-assessment responses respondent level but entail significant assumptions: They supposed be invariant respondents, prompts without...

Estimating the geographical position of mobile device such as Smart phone in an indoor environment is not easy without use specific infrastructures. In this article, we introduce user tracking system. The system constructs a topological map with Wi-Fi signal calibrations, assigns semantically meaningful labels into map, and estimates semantic location based on current observation. does require geometric or costly radio building process. We implemented off-the-shelf experimentally validated scheme.

Providing indoor location-based services is challenging due to the vast coverage required and scalability of positioning systems. This article proposes a participatory service platform for solve such problems. In proposed platform, few site trainers constructed an initial database locations through minimal intrusive actions. Thereafter, crowd users opportunistically contributed sensing data improve quality. The provides autonomous site-training tool sample application continuous...