1,559 research outputs found

    Machine Learning-based Indoor Positioning Systems Using Multi-Channel Information

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    The received signal strength indicator (RSSI) is a metric of the power measured by a sensor in a receiver. Many indoor positioning technologies use RSSI to locate objects in indoor environments. Their positioning accuracy is significantly affected by reflection and absorption from walls, and by non-stationary objects such as doors and people. Therefore, it is necessary to increase transceivers in the environment to reduce positioning errors. This paper proposes an indoor positioning technology that uses the machine learning algorithm of channel state information (CSI) combined with fingerprinting. The experimental results showed that the proposed method outperformed traditional RSSI-based localization systems in terms of average positioning accuracy up to 6.13% and 54.79% for random forest (RF) and back propagation neural networks (BPNN), respectively

    Machine Learning-based Indoor Positioning Systems Using Multi-Channel Information

    Get PDF
    The received signal strength indicator (RSSI) is a metric of the power measured by a sensor in a receiver. Many indoor positioning technologies use RSSI to locate objects in indoor environments. Their positioning accuracy is significantly affected by reflection and absorption from walls, and by non-stationary objects such as doors and people. Therefore, it is necessary to increase transceivers in the environment to reduce positioning errors. This paper proposes an indoor positioning technology that uses the machine learning algorithm of channel state information (CSI) combined with fingerprinting. The experimental results showed that the proposed method outperformed traditional RSSI-based localization systems in terms of average positioning accuracy up to 6.13% and 54.79% for random forest (RF) and back propagation neural networks (BPNN), respectively

    High-Mobility Pentacene-Based Thin-Film Transistors With a Solution-Processed Barium Titanate Insulator

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    Abstract—Pentacene-based organic thin-film transistors (OTFTs) with solution-processed barium titanate (Ba1.2Ti0.8O3) as a gate insulator are demonstrated. The electrical properties of pentacene-based TFTs show a high field-effect mobility of 8.85 cm2 · V−1 · s−1, a low threshold voltage of −1.89 V, and a low subthreshold slope swing of 310 mV/decade. The chemical composition and binding energy of solution-processed barium titanate thin films are analyzed through X-ray photoelectron spectroscopy. The matching surface energy on the surface of the barium titanate thin film is 43.12 mJ · m−2, which leads to Stranski–Krastanov mode growth, and thus, high mobility is exhibited in pentacene-based TFTs. Index Terms—Barium titanate, high field-effect mobility, high permittivity, organic thin-filmtransistor (OTFT), solution process

    U(1) CS Theory vs SL(2) CS Formulation: Boundary Theory and Wilson Line

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    We first derive the boundary theory from the U(1) Chern-Simons theory. We then introduce the Wilson line and discuss the effective action on an nn-sheet manifold from the back-reaction of the Wilson line. The reason is that the U(1) Chern-Simons theory can provide an exact effective action when introducing the Wilson line. This study cannot be done in the SL(2) Chern-Simons formulation of pure AdS3_3 Einstein gravity theory. It is known that the expectation value of the Wilson line in the pure AdS3_3 Einstein gravity is equivalent to entanglement entropy in the boundary theory up to classical gravity. We show that the boundary theory of the U(1) Chern-Simons theory deviates by a self-interaction term from the boundary theory of the AdS3_3 Einstein gravity theory. It provides a convenient path to the building of "minimum surface=entanglement entropy" in the SL(2) Chern-Simons formulation. We also discuss the Hayward term in the SL(2) Chern-Simons formulation to compare with the Wilson line approach. To reproduce the entanglement entropy for a single interval at the classical level, we introduce two wedges under a regularization scheme. We propose the quantum generalization by combining the bulk and Hayward terms. The quantum correction of the partition function vanishes. In the end, we exactly calculate the entanglement entropy for a single interval. The pure AdS3_3 Einstein gravity theory shows a shift of central charge by 26 at the one-loop level. The U(1) Chern-Simons theory does not have such a shift from the quantum effect, and the result is the same in the weak gravitational constant limit. The non-vanishing quantum correction shows the naive quantum generalization of the Hayward term is incorrect.Comment: 39 pages, 2 figure

    Existence theorems for a crystal surface model involving the p-Laplace operator

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    The manufacturing of crystal films lies at the heart of modern nanotechnology. How to accurately predict the motion of a crystal surface is of fundamental importance. Many continuum models have been developed for this purpose, including a number of PDE models, which are often obtained as the continuum limit of a family of kinetic Monte Carlo models of crystal surface relaxation that includes both the solid-on-solid and discrete Gaussian models. In this paper we offer an analytical perspective into some of these models. To be specific, we study the existence of a weak solution to the boundary value problem for the equation - \Delta e^{-\mbox{div}\left(|\nabla u|^{p-2}\nabla u\right)}+au=f, where p>1,a>0p>1, a>0 are given numbers and ff is a given function. This problem is derived from a crystal surface model proposed by J.L.~Marzuola and J.~Weare (2013 Physical Review, E 88, 032403). The mathematical challenge is due to the fact that the principal term in our equation is an exponential function of a p-Laplacian. Existence of a suitably-defined weak solution is established under the assumptions that p(1,2], N4p\in(1,2], \ N\leq 4, and fW1,pf\in W^{1,p}. Our investigations reveal that the key to our existence assertion is how to control the set where -\mbox{div}\left(|\nabla u|^{p-2}\nabla u\right) is ±\pm\infty

    Hepatitis B virus infection among pregnant women in Taiwan: Comparison between women born in Taiwan and other southeast countries

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    <p>Abstract</p> <p>Background</p> <p>Taiwan's national vaccination program has successfully decreased the prevalence of hepatitis B infection after twenty years of implementation and might be indirectly beneficial to the second generation. In this study, we compared the hepatitis B infection status of two groups: pregnant Taiwanese women and other Southeast Asian women, who because they had immigrated later in life to Taiwan by marriage to a Taiwanese man, had not been exposed to that vaccination program to evaluate the effect of hepatitis vaccination program on women of child-bearing age and further explored the potential impact of immigration on the hepatitis B public health policy in Taiwan.</p> <p>Methods</p> <p>Data was collected from 10,327 women born in Taiwan and 1,418 women born in other Southeast Asian countries, both groups receiving prenatal examinations at Fooyin University Hospital between 1996 and 2005. The results of serum hepatitis B s-Antigen (HBsAg) and hepatitis B e-Antigen (HBeAg) tests and other demographic data were obtained by medical chart review.</p> <p>Results</p> <p>The pregnant women from Taiwan had a higher HBsAg positive rate (15.5%) but lower HBeAg(+)/HBsAg(+) ratio (32.1%) than the women from other countries (8.9% and 52.4%). For those born before July, 1984, the period of no national vaccination program, Taiwanese women had a higher HBsAg positive rate than other Southeast Asian women (15.7% vs. 8.4%), but for women born after that day and before June 1986, the period of vaccination for high risk newborns, the HBsAg positive rates found to be slightly lower for Taiwanese women than for other Southeast Asian women (11.4% vs. 12.3%) and the difference was more significant (3.1% vs. 28.6%) after June 1986, the period of vaccination for all newborns. While the HBeAg(+)/HBsAg(+) ratios decreased with age in both groups, they were consistently higher in women from other Southeast Asian countries than in women born in Taiwan after age 20.</p> <p>Conclusion</p> <p>In Taiwan, the neonatal vaccination program that was implemented in 1984 has successfully reduced hepatitis B infection among pregnant women in present day, and is likely to indirectly prevent hepatitis B infection in the next generation. However, the increasing number of pregnant women from other Southeast Asian countries without a national neonatal vaccination program or with a program that was introduced later than the one in Taiwan will likely lessen the positive impact of this program and should be further assessed.</p

    Clinical significance of erythromycin-resistant Campylobacter jejuni in children

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    Campylobacter has been recognized as the common cause of bacterial gastroenteritis in many countries. Increasing erythromycin resistance in Campylobacter jejuni infection is noted recently, but severe case was rarely reported. In this study, we aimed to clarify the clinical significance of the resistant strain of C jejuni in children. We reviewed the charts of children who were diagnosed with C jejuni enteritis in our hospital from January 2000 to December 2005, including 326 patients (117 males and 209 females). All the cases had positive stool culture. We divided them into two groups, the sensitive group (a total of 306 cases) and resistant group (a total of 20 cases), according to the drug sensitivity. We analyzed the clinical manifestations and laboratory data between the two groups. The mean age was 3.79±3.24 years in the sensitive group and 3.03±2.84 years in the resistant group. There was no significant difference between the two groups in clinical presentations and laboratory examinations. No mortality was found, and one case was initially presented with colonic perforation. This report demonstrates that infection by erythromycin-resistant strains of C jejuni has no clinical significance in children, despite the probably increased emergence of erythromycin resistance

    ELEMENTARY SCHOOL BOYS’ SOCCER KICK SKILL ANALYSIS

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    The purpose of this study is aimed to analyze elementary school boys’ kicking skills on the perspective of motor skills. The data is collected by Vicon Motion Analysis System (250Hz). The parameters include the compare of the instant joint angles and the time proportion during the process of the kicking toward the different kick performance groups. The participants are 36 elementary boy soccer players (age: 11.7±0.3 yrs; height: 1.42±0.13 m; weight: 37.5±13.0 kg). The subjects were divided to two groups according to the instance kicking ball speed. The result indicated that the high ball speed group players have greater extremity joint angles than the low ball speed group. No difference was found on the time proportion during the process of the kicking. We suggest that the learning of kicking skill can start with the lower speed in the beginner stage

    A modified LLCL-filter with the reduced conducted EMI noise

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    Nanofibrous insulin/vildagliptin core-shell PLGA scaffold promotes diabetic wound healing

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    Introduction: Slow wound repair in diabetes is a serious adverse event that often results in loss of a limb or disability. An advanced and encouraging vehicle is wanted to enhance clinically applicable diabetic wound care. Nanofibrous insulin/vildagliptin core-shell biodegradable poly (lactic-co-glycolic acid) (PLGA) scaffolds to prolong the effective drug delivery of vildagliptin and insulin for the repair of diabetic wounds were prepared.Methods: To fabricate core-shell nanofibrous membranes, vildagliptin mixture with PLGA, and insulin solution were pumped via separate pumps into two differently sized capillary tubes that were coaxially electrospun.Results and Discussion: Nanofibrous core-shell scaffolds slowly released effective vildagliptin and insulin over 2 weeks in vitro migration assay and in vivo wound-healing models. Water contact angle (68.3 ± 8.5° vs. 121.4 ± 2.0°, p = 0.006) and peaked water absorbent capacity (376% ± 9% vs. 283% ± 24%, p = 0.003) of the insulin/vildagliptin core-shell nanofibrous membranes remarkably exceeded those of a control group. The insulin/vildagliptin-loaded core-shell nanofibers improved endothelial progenitor cells migration in vitro (762 ± 77 cells/mm2 vs. 424.4 ± 23 cells/mm2, p &lt; 0.001), reduced the α-smooth muscle actin content in vivo (0.72 ± 0.23 vs. 2.07 ± 0.37, p &lt; 0.001), and increased diabetic would recovery (1.9 ± 0.3 mm2 vs. 8.0 ± 1.4 mm2, p = 0.002). Core-shell insulin/vildagliptin-loaded nanofibers extend the drug delivery of insulin and vildagliptin and accelerate the repair of wounds associated with diabetes
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