710 research outputs found
Client-server-based LBS architecture: A novel positioning module for improved positioning performance
Permission to distribute obtained from publisher.This work presents a new efficient positioning module that operates over client-server LBS architectures. The
aim of the proposed module is to fulfil the position information requirements for LBS pedestrian applications
by ensuring the availability of reliable, highly accurate and precise position solutions based on GPS single
frequency (L1) positioning service. The positioning module operates at both LBS architecture sides; the client
(mobile device), and the server (positioning server). At the server side, the positioning module is responsible
for correcting user’s location information based on WADGPS corrections. In addition, at the mobile side,
the positioning module is continually in charge for monitoring the integrity and available of the position
solutions as well as managing the communication with the server. The integrity monitoring was based on
EGNOS integrity methods. A prototype of the proposed module was developed and used in experimental trials
to evaluate the efficiency of the module in terms of the achieved positioning performance. The positioning
module was capable of achieving a horizontal accuracy of less than 2 meters with a 95% confidence level
with integrity improvement of more than 30% from existing GPS/EGNOS services
Synthetic Aperture Focusing Technique Using the Envelope Function for Ultrasonic Imaging
In traditional ultrasonic imaging systems, a transducer is scanned across the surface of a specimen at constant intervals. Synthetic aperture focusing techniques (SAFT) have been utilized extensively to process the RF data in order to enhance the signal-to-noise ratio of the image [1]. However, the implementation of the algorithm using sampled RF data has the disadvantage of requiring large memory and high-speed devices. These requirements can be reduced by using the envelope of the RF signal which involves processing the baseband signal. The envelope detection can be easily implemented as part of the receiver circuit
Penggunaan Media Edu-Game Berbasis Ular Tangga Fisika dalam Pembelajaran Materi Gelombang pada Siswa Kelas XI SMA Negeri 1 Gorontalo
Penelitian ini bertujuan untuk mengetahui penggunaan media edu-game berbasis ular tangga Fisika dalam materi gelombang. Jenis penelitian yang digunakan pada penelitian ini adalah penelitan deskriptif dengan menggunakan pendekatan kuantitatif. Berdasarkan data yang diperoleh untuk lembar observasi aktivitas guru pada pertemuan I persentase aktivitas guru tercapai 95.2 %, pertemuan II tercapai 97.6 %, dan pertemuan III tercapai 98.8 %, sedangkan persentase aktivitas peserta didik pada pertemuan I tercapai 94.2 %, pertemuan II tercapai 96.8 %, dan pertemuan III tercapai 98 %. Angket minat peserta didik untuk indikator perasaan senang diperoleh rata-rata persentase 97.4 %, indikator perhatian diperoleh persentase rata-rata 94 %, indikator ketertarikan diperoleh rata-rata persentase 93.4 %, dan indikator keterlibatan peserta didik dalam belajar diperoleh rata-rata persentase 96 %. Hasil belajar peserta didik pada materi gelombang setelah diajarkan menggunakan media edu-game berbasis ular tangga Fisika dapat dilihat bahwa dari 30 orang peserta didik, 29 orang yang memenuhi KKM dan 1 orang yang tidak memenuhi KKM. Oleh karena itu, penggunaan media edu-game berbasis ular tangga Fisika pada pembelajaran materi gelombang pada peserta didik kelas XI IPA3 SMA Negeri 1 Gorontalo sudah maksimal atau sangat baik
Hybrid Wind Speed Prediction Model Using Intrinsic Mode Function (IMF) and Gradient Boosted Machine (GBM)
Before sitting a wind turbine, reliable wind speed prediction is prerequisite requirements that must be performed in order to get optimum energy yield. Single model has a lot of constraints in terms of prediction accuracy, to solve this persistent problem, this paper presents the application of hybrid model based on IMF and GBM so as to predict the wind speed in the areas with limited or absent of data. In the first place, the observed wind speed was decomposed into six using IMF in order to reduce ill-define stochastic nature of wind speed. The decomposed wind speed was used to train, test and validate the model developed GMB model which was developed in a Matlab environment. The final predicted values are obtained by summing all the individual prediction sub models. Wind speed data observed in the existing wind stations in Sarawak for a period of 1 year from 2017 to 2018 were used for the simulation. The model implementation confirmed that the proposed model is robust and capable to predict wind speed in remote and rural areas. A comparison with conventional method (ARIMA) was further investigated, the results showed the superiority of the new hybrid model over ARIMA
Aging in Dense Colloids as Diffusion in the Logarithm of Time
The far-from-equilibrium dynamics of glassy systems share important
phenomenological traits. A transition is generally observed from a
time-homogeneous dynamical regime to an aging regime where physical changes
occur intermittently and, on average, at a decreasing rate. It has been
suggested that a global change of the independent time variable to its
logarithm may render the aging dynamics homogeneous: for colloids, this entails
diffusion but on a logarithmic time scale. Our novel analysis of experimental
colloid data confirms that the mean square displacement grows linearly in time
at low densities and shows that it grows linearly in the logarithm of time at
high densities. Correspondingly, pairs of particles initially in close contact
survive as pairs with a probability which decays exponentially in either time
or its logarithm. The form of the Probability Density Function of the
displacements shows that long-ranged spatial correlations are very long-lived
in dense colloids. A phenomenological stochastic model is then introduced which
relies on the growth and collapse of strongly correlated clusters ("dynamic
heterogeneity"), and which reproduces the full spectrum of observed colloidal
behaviors depending on the form assumed for the probability that a cluster
collapses during a Monte Carlo update. In the limit where large clusters
dominate, the collapse rate is ~1/t, implying a homogeneous, log-Poissonian
process that qualitatively reproduces the experimental results for dense
colloids. Finally an analytical toy-model is discussed to elucidate the strong
dependence of the simulation results on the integrability (or lack thereof) of
the cluster collapse probability function.Comment: 6 pages, extensively revised, final version; for related work, see
http://www.physics.emory.edu/faculty/boettcher/ or
http://www.fysik.sdu.dk/staff/staff-vip/pas-personal.htm
An Overview of Active Structural Control under Seismic Loads
The concept of active structural control as a means of structural protection against seismic loads, developed over the last 20 years, has received considerable attention in recent years. It has now reached the stage where active systems have been installed in full-scale structures. It is the purpose of this paper to provide an overview of this development with special emphasis placed on laboratory experiments using model structures and on full-scale implementation of some active control systems. Included in this paper is a report on the formation of a U.S. Panel on Structural Control Research and some discussion on possible future research directions in this exciting research area
The Physics of the Colloidal Glass Transition
As one increases the concentration of a colloidal suspension, the system
exhibits a dramatic increase in viscosity. Structurally, the system resembles a
liquid, yet motions within the suspension are slow enough that it can be
considered essentially frozen. This kinetic arrest is the colloidal glass
transition. For several decades, colloids have served as a valuable model
system for understanding the glass transition in molecular systems. The spatial
and temporal scales involved allow these systems to be studied by a wide
variety of experimental techniques. The focus of this review is the current
state of understanding of the colloidal glass transition. A brief introduction
is given to important experimental techniques used to study the glass
transition in colloids. We describe features of colloidal systems near and in
glassy states, including tremendous increases in viscosity and relaxation
times, dynamical heterogeneity, and ageing, among others. We also compare and
contrast the glass transition in colloids to that in molecular liquids. Other
glassy systems are briefly discussed, as well as recently developed synthesis
techniques that will keep these systems rich with interesting physics for years
to come.Comment: 56 pages, 18 figures, Revie
The power of PISA – limitations and possibilities for educational research
On 6th December 2016, the Programme for International Student Assessment (PISA) releases its report on the achievements of 15-year-olds from 72 countries and economies around the world. This triennial international survey aims to evaluate education systems across 72 contexts by testing skills in Mathematics, Science and Reading Literacy. This is the sixth cycle of PISA and the OECD suggests countries and economies now have the capability to compare the results over time to ‘assess the impact of education policy decisions’ . Compared to other education studies, the media coverage of PISA must be described as massive (Meyer and Benavot, 2013, Baird et al., 2016) and, as with previous years, it is expected that PISA will attract considerable discussion among policy makers, educators and researchers (Wiseman, 2014). It is therefore timely to present a thematic issue of Assessment in Education, where we publish four articles that have analysed previous datasets from the PISA studies each commenting upon the challenges, limitations and potential future assessment research on the PISA data.
The articles touch upon issues regarding sampling, language, item difficulty and demands, as well as the secondary analyses of students’ reported experiences of formative assessment in the classroom. One important message from the authors in this thematic Special Issue is the need for a more complex discussion around the use and misuse of PISA data, and the importance of pointing to the limitations of how the results are presented to policy makers and the public. In an area where the media produces narratives on schools and education systems based upon rankings in PISA, researchers in the field of large-scale assessment studies have a particularly important role in stepping up and advising on how to interpret and understand these studies, while warning against potential misuse. </p
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