排序方式： 共有70条查询结果，搜索用时 421 毫秒
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The motivations and benefits of educational travel among individuals aged 55 years old and over were examined in this study. A total of 136 older adults enrolled in Elderhostel programs participated in this study and reported their perceived benefits and motivations for engaging in educational travel experiences. Correlation analyses were used to explore relationships between the adults' perceived benefits and motivations. Analyses of variance were conducted and significant differences in adults' motivations for educational travel were found by gender, education level, health, and activity level of the program. The findings from this study are discussed in terms of successful aging, and implications for organizations offering educational travel programs are provided. 相似文献
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For state estimation of high accuracy, prior knowledge of measurement noise is necessary. In this paper, a method for solving the joint state estimation problem of jump Markov nonlinear systems (JMNSs) without knowing the measurement noise covariance is developed. By using the Inverse-Gamma distribution to describe the dynamics of measurement noise covariance, the joint conditional posterior distribution of the state variable and measurement noise covariance is approximated by a product of separable variational Bayesian (VB) marginals. In the newly constructed approach, the interacting multiple model (IMM) algorithm, as well as the particle-based approximation strategy, is employed to handle the computationally intractable problem and the nonlinear characteristics of systems, respectively. An interesting feature of the proposed method is that the distribution of states is spanned by a set of particles with weights, while the counterpart of measurement noise covariance is obtained analytically. Moreover, the number of particles is fixed under each mode, indicating a reasonable computational cost. Simulation results based on a numerical example and a tunnel diode circuit (TDC) system are presented to demonstrate that the proposed method can estimate the measurement noise covariance well and provide satisfied state estimation when the statistics of the measurement are unavailable. 相似文献
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Jae-wook Ahn Peter Brusilovsky Jonathan Grady Daqing He Radu Florian 《Information processing & management》2010,46(4):383-402
The system presented in this article aims to improve information access through the use of semantic annotation utilizing a non-traditional approach. Instead of applying semantic annotations to enhance the internal information access mechanisms, we use them to empower the user of an information access system through an innovative named entity-based user interface – NameSieve. NameSieve was built to support an intelligence analyst during the process of exploratory search, an advanced type of search requiring multiple iterations of retrieval interleaved with browsing and analyzing the retrieved information. The proposed approach was implemented in the NameSieve system so that the system can transparently present a summary of search results in the form of entity “clouds.” Therefore, these clouds allow the analyst to further explore the results in a novel manner, acting together as a faceted browsing interface. We ran a user study (with ten subjects) to examine the effect of NameSieve, and the study results reported in the paper demonstrate that this new way of applying semantic annotation information was actively used and was evaluated positively by the subjects. It enabled the subjects to work more productively and bring back most relevant documents. 相似文献
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Youngsok Bang Dong-Joo Lee Yoon-Soo Bae Jae-Hyeon Ahn 《International Journal of Information Management》2012
Statistics show that the number of identity theft victims in the US increased by 12% in 2009, to 11.1 million adults, while the total annual fraud amount increased by 12.5%, to $54 billion. As the e-commerce volume is increasing and various online services are becoming more popular, the number of sites to which an average Internet user subscribes is increasing rapidly. Given the limited memory capacity of human beings, an Internet user's login credentials (in the form of a combination of a user ID and a password) are usually reused over multiple accounts, which can cause significant security problems. In this study, we address the vulnerability of login credentials. First, based on a unique Internet user data set, we analyze the behavioral characteristics of login credentials usage. We find that the same login credentials are used for many more accounts and reused much more often than previously expected. Furthermore, usage patterns are found to be quite skewed. Second, building on a network perspective of login credentials usage, we suggest a vulnerability measure of an individual's login credentials and analyze the vulnerability of current Internet users. The resulting information is valuable not only to the research community but also to managers and policy makers striving to reduce security vulnerability. 相似文献
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Alicia L. Fedewa Colleen Cornelius Heather E. Erwin Soyeon Ahn Claire Stai 《The Journal of educational research》2018,111(5):584-593
Little research has explored the impact of teacher behavior in the relationship between classroom movement breaks and student outcomes. The authors' primary purpose was to explore teacher behavior during classroom movement breaks to determine if teacher behavior served as a moderating variable in the relationship between physical activity and student achievement. The second major aim was to examine these relationships across two different types of movement breaks: (a) academic-content movement breaks and (b) aerobic-based movement breaks. Children (n = 466) in Grades 3–5 from four elementary schools served as participants in the study. Results found that teachers who encouraged students to move and teachers who moved themselves did not necessary have students with higher activity levels during the movement breaks. However, significant differences across the type of movement break provided were found. Implications and limitations are discussed. 相似文献
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Nicholas D. Myers Soyeon Ahn Min Lu Seniz Celimli Cengiz Zopluoglu 《Structural equation modeling》2017,24(1):112-128
This article describes the REREFACT R package, which provides a postrotation algorithm that reorders or reflects factors for each replication of a simulation study with exploratory factor analysis (EFA). The purpose of REREFACT is to provide a general algorithm written in freely available software, R, dedicated to addressing the possibility that a nonuniform order or sign pattern of the factors could be observed across replications. The algorithm implemented in REREFACT proceeds in 4 steps. Step 1 determines the total number of equivalent forms, I, of the vector of factors, η. Step 2 indexes, i = 1, 2 … I, each equivalent form of η (i.e., ηi) via a unique permutation matrix, P (i.e., Pi). Step 3 determines which ηi each replication follows. Step 4 uses the appropriate Pi to reorder or re-sign parameter estimates within each replication so that all replications uniformly follow the order and sign pattern defined by the population values. Results from two simulation studies provided evidence for the efficacy of the REREFACT to identify and remediate equivalent forms of η in models with EFA only (i.e., Example 1) and in fuller parameterizations of exploratory structural equation modeling (i.e., Example 2). How to use REREFACT is briefly demonstrated prior to the Discussion section by providing annotations for key commands and condensed output using a subset of simulated data from Example 1. 相似文献
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Daqing He Peter Brusilovsky Jaewook Ahn Jonathan Grady Rosta Farzan Yefei Peng Yiming Yang Monica Rogati 《Information processing & management》2008
Exploratory search increasingly becomes an important research topic. Our interests focus on task-based information exploration, a specific type of exploratory search performed by a range of professional users, such as intelligence analysts. In this paper, we present an evaluation framework designed specifically for assessing and comparing performance of innovative information access tools created to support the work of intelligence analysts in the context of task-based information exploration. The motivation for the development of this framework came from our needs for testing systems in task-based information exploration, which cannot be satisfied by existing frameworks. The new framework is closely tied with the kind of tasks that intelligence analysts perform: complex, dynamic, and multiple facets and multiple stages. It views the user rather than the information system as the center of the evaluation, and examines how well users are served by the systems in their tasks. The evaluation framework examines the support of the systems at users’ major information access stages, such as information foraging and sense-making. The framework is accompanied by a reference test collection that has 18 tasks scenarios and corresponding passage-level ground truth annotations. To demonstrate the usage of the framework and the reference test collection, we present a specific evaluation study on CAFÉ, an adaptive filtering engine designed for supporting task-based information exploration. This study is a successful use case of the framework, and the study indeed revealed various aspects of the information systems and their roles in supporting task-based information exploration. 相似文献
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Meta-analysis is a class of statistical methods for combining the results from a series of studies addressing the same research
question. These methods can powerfully test hypotheses that cannot be answered clearly with one or a few studies and eliminates
the ambiguity that results from narrative reviews of a research literature or from counting the number of studies that support
a particular conclusion. The usefulness of meta-analysis is demonstrated by reviewing instances in psychotherapy, education,
and medicine that show how meta-analysis was used successfully to end acrimonious debate and reach a firm and lasting conclusion. 相似文献