954 research outputs found

    Supersonic boundary-layer flow turbulence modeling

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    Baldwin-Lomax and kappa-epsilon turbulence models were modified for use in Navier-Stokes numerical computations of Mach 2.9 supersonic turbulent boundary layer flows along compression ramps. The computational results of Reynolds shear stress profiles were compared with experimental data. The Baldwin-Lomax model was modified to account for the Reynolds shear stress amplification within the flow field. A hybrid kappa-epsilon model with viscous sublayer turbulence treatment was constructed to predict the Reynolds shear stress profiles within the entire flow field. These modified turbulence models were effective for the computations of the surface pressure and the skin friction factor variations along an 8 deg ramp surface. The hybrid kappa-epsilon model could improve the predictions of the Reynolds shear stress profile and the skin friction factor near the corner of a 16 deg ramp

    Examining the Validity of the Exemplar-Based Classifier in Identifying Decision Strategy with Eye-Movement Data

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    In this study, an exemplar-based classifier was developed to predict which decision strategy may underlie an empirical ocular search behavior. Our rationale was mainly inspired by the exemplar-based models of categorization; that is, different decision strategies are conceived as different concepts, with the exemplar referring to the sequence of empirical fixations on decision information during a decision process. In order to ascertain the best exemplar of each strategy for our classifier, the Tabu search algorithm was applied. An eye-tracking based experiment was conducted to collect fixation data for training and validation. Our result showed that the classifier has significant accuracy in identifying underlying strategies, achieving an average hit-ratio of 76%. This indicated to us that the integration of the exemplar classifier with fixation data has certain applicable value for leveraging the adaptability of DSSs. Our result also has some important implications for the direction and methodology of behavioral decision researc

    An Evaluation of Taiwanese B&B Service Quality Using the IPA Model

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    According to a December 2011 report released by Taiwan’s Tourism Bureau, there were 3,763 bed-and-breakfast guesthouses (B&B) in Taiwan, 3,367 of which were legal with a combined 13,389 rooms, increasing by 96 percent from December 2006. It seems that the B&B sector is quite a popular target for investors. As the word-of-mouth advertising has been considered one of the most influential marketing methods, those who invest in B&Bs must manage to utilize their limited resources to improve customer satisfaction in a fast-growing and competitive market. The best marketing approach in reaching out to B&B customers, as suggested by this study’s author, would be word-of-mouth adverting. A PZB framed questionnaire is used in this study to explore the expectations and satisfaction of B&B customers both before and after the accommodation period, with the Importance-Performance Analysis (IPA) model applied to analyze and measure the service quality. Findings from the questionnaire survey showed 3 out of the totally 23 service factors falling in the “concentrated concerned” quadrant (i.e., tidiness, architectural characteristics, and reasonable rates); 6 factors falling in the “continued maintenance” quadrant (i.e., adequate parking place, commitment to customers, handling of customers’ opinions, legality of B&B, grievance handling, and the local specialties-ordering service); 10 factors falling in the “low priority” quadrant (i.e., modern facilities, safety devices, availability of breakfast, security of online reservations); 4 factors falling in the “over-strived” quadrant (i.e., the availability of custom-made services, the ability to grasp customers’ needs, the availability of tour packages, and the availability of experiences regarding local industries)

    On-machine surface defect detection using light scattering and deep learning

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    This paper presents an on-machine surface defect detection system using light scattering and deep learning. A supervised deep learning model is used to mine the information related to defects from light scattering patterns. A convolutional neural network is trained on a large dataset of scattering patterns that are predicted by a rigorous forward scattering model. The model is valid for any surface topography with homogeneous materials and has been verified by comparing with experimental data. Once the neural network is trained, it allows for fast, accurate and robust defect detection. The system capability is validated on micro-structured surfaces produced by ultra-precision diamond machining

    Cloud-based Automatic Speech Recognition Systems for Southeast Asian Languages

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    This paper provides an overall introduction of our Automatic Speech Recognition (ASR) systems for Southeast Asian languages. As not much existing work has been carried out on such regional languages, a few difficulties should be addressed before building the systems: limitation on speech and text resources, lack of linguistic knowledge, etc. This work takes Bahasa Indonesia and Thai as examples to illustrate the strategies of collecting various resources required for building ASR systems.Comment: Published by the 2017 IEEE International Conference on Orange Technologies (ICOT 2017

    Single-nucleotide polymorphism-based genetic risk score and patient age at prostate cancer diagnosis

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    Importance: Few studies have evaluated the association between a single-nucleotide polymorphism-based genetic risk score (GRS) and patient age at prostate cancer (PCa) diagnosis. Objectives: To test the association between a GRS and patient age at PCa diagnosis and to compare the performance of a GRS with that of family history (FH) in PCa risk stratification. Design, Setting, and Participants: A cohort study of 3225 white men was conducted as a secondary analysis of the Reduction by Dutasteride of Prostate Cancer Events (REDUCE) chemoprevention trial, a 4-year, randomized, double-blind, placebo-controlled multicenter study conducted from March 2003 to April 2009 to evaluate the safety and efficacy of dutasteride in reducing PCa events. Participants were confirmed to be cancer free by prostate biopsy (6-12 cores) within 6 months prior to the study and underwent 10 core biopsies every 2 years per protocol. The dates for performing data analysis were from July 2016 to October 2019. Interventions: A well-established, population-standardized GRS was calculated for each participant based on 110 known PCa risk-associated single-nucleotide polymorphisms, which is a relative risk compared with the general population. Men were classified into 3 GRS risk groups based on predetermined cutoff values: low (\u3c0.50), average (0.50-1.49), and high (≥1.50). Main Outcomes and Measures: Prostate cancer diagnosis-free survival among men of different risk groups. Results: Among 3225 men (median age, 63 years [interquartile range, 58-67 years]) in the study, 683 (21%) were classified as low risk, 1937 (60%) as average risk, and 605 (19%) as high risk based on GRS alone. In comparison, 2789 (86%) were classified as low or average risk and 436 (14%) as high risk based on FH alone. Men in higher GRS risk groups had a PCa diagnosis-free survival rate that was worse than that of those in the lower GRS risk group (χ2 = 53.3; P \u3c .001 for trend) and in participants with a negative FH of PCa (χ2 = 45.5; P \u3c .001 for trend). Combining GRS and FH further stratified overall genetic risk, indicating that 957 men (30%) were at high genetic risk (either high GRS or positive FH), 1667 men (52%) were at average genetic risk (average GRS and negative FH), and 601 men (19%) were at low genetic risk (low GRS and negative FH). The median PCa diagnosis-free survival was 74 years (95% CI, 73-75 years) for men at high genetic risk, 77 years (95% CI, 75 to \u3e80 years) for men at average genetic risk, and more than 80 years (95% CI, \u3e80 to \u3e80 years) for men at low genetic risk. In contrast, the median PCa diagnosis-free survival was 73 years (95% CI, 71-76 years) for men with a positive FH and 77 years (95% CI, 76-79 years) for men with a negative FH. Conclusions and Relevance: This study suggests that a GRS is significantly associated with patient age at PCa diagnosis. Combining FH and GRS may better stratify inherited risk than FH alone for developing personalized PCa screening strategies

    Ellagic Acid, the Active Compound of Phyllanthus urinaria, Exerts In Vivo Anti-Angiogenic Effect and Inhibits MMP-2 Activity

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    This study aimed to assess the potential anti-angiogenic mechanism of Phyllanthus urinaria (P. urinaria) and characterize the major compound in P. urinaria that exerts anti-angiogenic effect. The water extract of P. urinaria and Ellagic Acid were used to evaluate the anti-angiogenic effect in chorioallantoic membrane (CAM) in chicken embryo and human vascular endothelial cells (HUVECs). The matrix metalloproteinase-2 (MMP-2) activity was determined by gelatin zymography. The mRNA expressions of MMP-2, MMP-14 and tissue inhibitor of metalloproteinase-2 (TIMP-2) were analyzed by reverse transcription polymerase chain reaction (RT-PCR). Level of MMP-2 proteins in conditioned medium or cytosol was determined by western blot analysis. We confirmed that P. urinaria's in vivo anti-angiogenic effect was associated with a reduction in MMP-2 activity. Ellagic acid, one of the major polyphenolic components as identified in P. urinaria by high performance liquid chromatography mass spectrometry (HPLC/MS), exhibited the same anti-angiogenic effect in vivo. Both P. urinaria and Ellagic Acid inhibited MMP-2 activity in HUVECs with unchanged mRNA level. The mRNA expression levels of MMP-14 and TIMP-2 were not altered either. Results from comparing the change of MMP-2 protein levels in conditioned medium and cytosol of HUVECs after the P. urinaria or Ellagic Acid treatment revealed an inhibitory effect on the secretion of MMP-2 protein. This study concluded that Ellagic Acid is the active compound in P. urinaria to exhibit anti-angiogenic activity and to inhibit the secretion of MMP-2 protein from HUVECs

    Taiwan Oscillation Network

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    The Taiwan Oscillation Network (TON) is a ground-based network to measure solar intensity oscillations to study the internal structure of the Sun. K-line full-disk images of 1000 pixels diameter are taken at a rate of one image per minute. Such data would provide information onp-modes withl as high as 1000. The TON will consist of six identical telescope systems at proper longitudes around the world. Three telescope systems have been installed at Teide Observatory (Tenerife), Huairou Solar Observing Station (near Beijing), and Big Bear Solar Observatory (California). The telescopes at these three sites have been taking data simultaneously since October of 1994. Anl – v diagram derived from 512 images is included to show the quality of the data

    A New Global Router for Modern Designs

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    Abstract -In this paper, we present a new global router, NTHU-Route, for modern designs. NTHU-Route is based on iterative rip-ups and reroutes, and several techniques are proposed to enhance our global router. These techniques include (1) a history based cost function which helps to distribute overflow during iterative rip-ups and reroutes, (2) an adaptive multi-source multi-sink maze routing method to improve the wirelength of maze routing, (3) a congested region identification method to specify the order for nets to be ripped up and rerouted, and (4) a refinement process to further reduce overflow when iterative history based rip-ups and reroutes reach bottleneck. Compared with two state-of-the-art works on ISPD98 benchmarks, NTHU-Route outperforms them in both overflow and wirelength. For the much larger designs from the ISPD07 benchmark suite, our solution quality is better than or comparable to the best results reported in the ISPD07 routing contest. I Introduction In the recent years, feature size continues to shrink. Although the device becomes smaller and faster, the shrinkage increases the wire resistance and hence interconnect delay. Interconnect delay has replaced transistor delay as the main determinant of chip performance. Therefore the routing problem is becoming even more important in VLSI design. Typically, the routing problem can be divided into two steps due to the problem complexity: global routing and detailed routing. During global routing, nets are connected on a coarse-grain grid graph with capacity constraints. Then detailed routing follows the solution in global routing to find the exact routing solution. The quality of global routing affects timing, power and density in the chip area, and thus global routing is a very important stage in the design cycle. Recent global routing techniques can be roughly categorized into two classes: multicommodity flow based techniques and rip-up and reroute techniques. Multicommodity flow based techniques Rip-up and reroute approach starts by routing each net without considering congestion. After routing all nets, congested areas can be identified and the nets in those areas are ripped up and rerouted to find less congested routes. This approach is a sequential one since the net to be ripped up and rerouted has to follow a specific order. Therefore the routing order in rip-up and reroute techniques affects the solution quality a lot. Chi Dispersion In this paper, we present a new global router, NTHU-Route, for modern designs. NTHU-Route is based on iterative rip-ups and reroutes, and several techniques are proposed to enhance our global router. These techniques include (1) a history based cost function which helps to distribute overflow during iterative rip-ups and reroutes, (2) an adaptive multi-source multi-sink maze routing method to improve the wirelength of maze routing, (3) a congested region identification method to specify the order for nets to be ripped up and rerouted, and (4) a refinement process to further reduce overflow when iterative history based rip-ups and reroutes reach bottleneck. We compare our results with two state-of-the-art works, BoxRouter and FastRoute, on ISPD98 benchmarks. Our global router solves all benchmarks without any overflow and respectively reduces the wirelength over BoxRouter and FastRoute by 1.93% and 2.59% on average. We also perform our router on ISPD07 benchmarks which contain multi-layer designs with larger size. The experiments show that our router obtains the solution with least overflow when comparing with the best results reported in the ISPD07 global routing contest. The rest of the paper is organized as follows. Section II gives the preliminaries including the problem formulation and introduction for some routing techniques. In section III, we present our global router in detail. Section IV provides the experimental results and we conclude the paper in section V
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