• Title/Summary/Keyword: signed distance

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Design of a Fuzzy Logic Controller for a Rotary-type Inverted Pendulum System

  • Park, Byung-Jae;Ryu, Chun-ha;Choi, Bong-Yeol
    • International Journal of Fuzzy Logic and Intelligent Systems
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    • v.2 no.2
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    • pp.109-114
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    • 2002
  • Various inverted pendulum systems have been frequently used as a model for the performance test of the proposed control system. We first identify a rotary-type inverted pendulum system by the Euler-Lagrange method and then design a FLC (Fuzzy Logic Controller) fur the plant. FLC`s are one of useful control schemes fur plants having difficulties in deriving mathematical models or having performance limitations with conventional linear control schemes. Many FLC`s imitate the concept of conventional PD (Proportional-Derivative) or PI (Proportional-Integral) controller. That is, the error e and the change-of-error are used as antecedent variables and the control input u the change of control input Au is used as its consequent variable for FLC`s. In this paper we design a simple-structured FLC for the rotary inverted pendulum system. We also perform some computer simulations to examine the tracking performance of the closed-loop system.

Determinants of Intra-Industry Trade between Vietnam and Countries in TPP

  • NGUYEN, Ha Minh;QUAN, Binh Quoc Minh;LE, Huong Van;TRAN, Thinh Van
    • The Journal of Asian Finance, Economics and Business
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    • v.7 no.1
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    • pp.123-129
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    • 2020
  • Intra-industry trade (IIT) has played an important role in international trade of Vietnam as a result of rapid growth of the country. This article investigates the level of IIT between Vietnam and 11 trading partners in Trans-Pacific Partnership (TPP) over the period 2000-2014. Although there have been a large number of empirical researches contributed to the determinants of IIT, most of them only pay attention on developed countries where the trade flows are similar due to similar demand structure and production technology. Until now, there is no study on intra-industry trade between Vietnam and countries in TPP that Vietnam recently signed a trade agreement in early 2016. IIT is measured by the Grubel-Lloyd index. The index shows that the extent of intra-industry trade between Vietnam and the trading countries is not high due to the level of economic development and the market size. The determinants of IIT are examined using a panel regression model. In the empirical analysis, the results indicate that Vietnam's intra-industry trade is positively correlated with country size, while it is negatively correlated with income dissimilarity, the trade openness, and geographical distance. This study contributes to the new theoretical trade theory on the evidence of developing country's IIT.

Analysis on Spatial Sampling and Implementation for Primal Trees (Primal Tree의 공간 분할 샘플링 분석 및 구현)

  • Park, Taejung
    • Journal of Digital Contents Society
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    • v.15 no.3
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    • pp.347-355
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    • 2014
  • The general octree structure is common for various applications including computer graphics, geometry information analysis and query. Unfortunately, the general octree approach causes duplicated sample data and discrepancy between sampling and representation positions when applied to sample continuous spatial information, for example, signed distance fields. To address these issues, some researchers introduced the dual octree. In this paper, the weakness of the dual octree approach will be illustrated by focusing on the fact that the dual octree cannot access some specific continuous zones asymptotically. This paper shows that the primal tree presented by Lefebvre and Hoppe can solve all the problems above. Also, this paper presents a three-dimensional primal tree traversal algorithm based the Morton codes which will help to parallelize the primal tree method.

The Effect of Treadmill Training Applied Simultaneously with Action Observation on Walking Ability in Chronic Stroke Patients

  • Song, Yo-han;Lee, Hyun-min
    • The Journal of Korean Physical Therapy
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    • v.28 no.3
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    • pp.176-182
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    • 2016
  • Purpose: To investigate the effect of treadmill training applied simultaneously with gait related action observation on walking ability in chronic stroke patients. Methods: Sixteen chronic stroke patients participated in this study. Participants were randomly allocated into either the treadmill applied simultaneously with action observation training group (TAG) or treadmill applied simultaneously with landscape observation training group (TLG). The participants in both group underwent treadmill training for four weeks (a total of twelve minute, once a day, three times weekly for a four week period). All participants were measured to gait speed (10 m walking test, 10 MWT), gait endurance (6 minute walk distance, 6 MWD), dynamic gait index (DGI). In order to assure the statistical significance of the results, we used for SPSS 15.0 for windows. The Wilcoxon signed ranks test was used to compare pre-test and post-test result, and the Mann-Whitney U-test was employed for comparison between groups. Results: The 10 MWT, 6 MWD, DGI was significantly different between the TAG and the TLG group. Conclusion: According the results of this study, treadmill applied simultaneously with action observation (TAG) is effective intervention for improvement of walking ability in chronic stroke patient.

Augmentation of Fractional-Order PI Controller with Nonlinear Error-Modulator for Enhancing Robustness of DC-DC Boost Converters

  • Saleem, Omer;Rizwan, Mohsin;Khizar, Ahmad;Ahmad, Muaaz
    • Journal of Power Electronics
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    • v.19 no.4
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    • pp.835-845
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    • 2019
  • This paper presents a robust-optimal control strategy to improve the output-voltage error-tracking and control capability of a DC-DC boost converter. The proposed strategy employs an optimized Fractional-order Proportional-Integral (FoPI) controller that serves to eliminate oscillations, overshoots, undershoots and steady-state fluctuations. In order to significantly improve the error convergence-rate during a transient response, the FoPI controller is augmented with a pre-stage nonlinear error-modulator. The modulator combines the variations in the error and error-derivative via the signed-distance method. Then it feeds the aggregated-signal to a smooth sigmoidal control surface constituting an optimized hyperbolic secant function. The error-derivative is evaluated by measuring the output-capacitor current in order to compensate the hysteresis effect rendered by the parasitic impedances. The resulting modulated-signal is fed to the FoPI controller. The fixed controller parameters are meta-heuristically selected via a Particle-Swarm-Optimization (PSO) algorithm. The proposed control scheme exhibits rapid transits with improved damping in its response which aids in efficiently rejecting external disturbances such as load-transients and input-fluctuations. The superior robustness and time-optimality of the proposed control strategy is validated via experimental results.

Comparison of crown designs of different dental occupational groups, using CAD-CAM (CAD-CAM을 이용하여 디자인한 금관의 치과 직업군에 따른 형태 비교)

  • Kim, TaeHyeon;Kim, Jong-Eun;Lee, Ah-Reum;Park, Young-Bum
    • The Journal of Korean Academy of Prosthodontics
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    • v.54 no.3
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    • pp.234-238
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    • 2016
  • Purpose: Increasing use of computer aided design-computer aided manufacturing (CAD-CAM) system and number of design software made design of restoration easy and quick. Outcome of restoration has been dependent on dental technician's wax up proficiency, dentists can design restoration for themselves now. This study aims to investigate the outcome of restoration designs, according to handling skill of CAD-CAM design tool. Materials and methods: A patient's mandibular right 1st molar was prepared. After taking impression, stone model was made, scanned the stone model with 3 shape intra-oral scanner, stereolithography (STL) file was extracted. With 3shape dental designer, one dental technician with more than 5 years work experience (designer 0) and three dental technicians with less than 2years work experience (designer 1, 2, 3-group DT) and 4 1st year residents (designer 4, 5, 6, 7-group RT) designed gold crown on the same STL file. Designed crown's MD (mesio-distal) and BL (bucco-lingual) diameter, height of crown, inter-cuspal distance, number of occlusal contact points were compared. Statistical analysis was carried out, test of normality within each group, using independent t-test. Number of contact points were compared, using Wilcoxon signed-rank test. Results: There was no significant difference between group DT and group RT. Number of contact points also resulted in no significant difference. Conclusion: The outcome of each designed crowns showed no statistical differences, in values which can be expressed as numbers. Subjective factors were different. With increasing proficiency in handling designing software, fabrication of restorations according to each designer's occlusal concept can be made easy.

Intelligent Optimal Route Planning Based on Context Awareness (상황인식 기반 지능형 최적 경로계획)

  • Lee, Hyun-Jung;Chang, Yong-Sik
    • Asia pacific journal of information systems
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    • v.19 no.2
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    • pp.117-137
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    • 2009
  • Recently, intelligent traffic information systems have enabled people to forecast traffic conditions before hitting the road. These convenient systems operate on the basis of data reflecting current road and traffic conditions as well as distance-based data between locations. Thanks to the rapid development of ubiquitous computing, tremendous context data have become readily available making vehicle route planning easier than ever. Previous research in relation to optimization of vehicle route planning merely focused on finding the optimal distance between locations. Contexts reflecting the road and traffic conditions were then not seriously treated as a way to resolve the optimal routing problems based on distance-based route planning, because this kind of information does not have much significant impact on traffic routing until a a complex traffic situation arises. Further, it was also not easy to take into full account the traffic contexts for resolving optimal routing problems because predicting the dynamic traffic situations was regarded a daunting task. However, with rapid increase in traffic complexity the importance of developing contexts reflecting data related to moving costs has emerged. Hence, this research proposes a framework designed to resolve an optimal route planning problem by taking full account of additional moving cost such as road traffic cost and weather cost, among others. Recent technological development particularly in the ubiquitous computing environment has facilitated the collection of such data. This framework is based on the contexts of time, traffic, and environment, which addresses the following issues. First, we clarify and classify the diverse contexts that affect a vehicle's velocity and estimates the optimization of moving cost based on dynamic programming that accounts for the context cost according to the variance of contexts. Second, the velocity reduction rate is applied to find the optimal route (shortest path) using the context data on the current traffic condition. The velocity reduction rate infers to the degree of possible velocity including moving vehicles' considerable road and traffic contexts, indicating the statistical or experimental data. Knowledge generated in this papercan be referenced by several organizations which deal with road and traffic data. Third, in experimentation, we evaluate the effectiveness of the proposed context-based optimal route (shortest path) between locations by comparing it to the previously used distance-based shortest path. A vehicles' optimal route might change due to its diverse velocity caused by unexpected but potential dynamic situations depending on the road condition. This study includes such context variables as 'road congestion', 'work', 'accident', and 'weather' which can alter the traffic condition. The contexts can affect moving vehicle's velocity on the road. Since these context variables except for 'weather' are related to road conditions, relevant data were provided by the Korea Expressway Corporation. The 'weather'-related data were attained from the Korea Meteorological Administration. The aware contexts are classified contexts causing reduction of vehicles' velocity which determines the velocity reduction rate. To find the optimal route (shortest path), we introduced the velocity reduction rate in the context for calculating a vehicle's velocity reflecting composite contexts when one event synchronizes with another. We then proposed a context-based optimal route (shortest path) algorithm based on the dynamic programming. The algorithm is composed of three steps. In the first initialization step, departure and destination locations are given, and the path step is initialized as 0. In the second step, moving costs including composite contexts into account between locations on path are estimated using the velocity reduction rate by context as increasing path steps. In the third step, the optimal route (shortest path) is retrieved through back-tracking. In the provided research model, we designed a framework to account for context awareness, moving cost estimation (taking both composite and single contexts into account), and optimal route (shortest path) algorithm (based on dynamic programming). Through illustrative experimentation using the Wilcoxon signed rank test, we proved that context-based route planning is much more effective than distance-based route planning., In addition, we found that the optimal solution (shortest paths) through the distance-based route planning might not be optimized in real situation because road condition is very dynamic and unpredictable while affecting most vehicles' moving costs. For further study, while more information is needed for a more accurate estimation of moving vehicles' costs, this study still stands viable in the applications to reduce moving costs by effective route planning. For instance, it could be applied to deliverers' decision making to enhance their decision satisfaction when they meet unpredictable dynamic situations in moving vehicles on the road. Overall, we conclude that taking into account the contexts as a part of costs is a meaningful and sensible approach to in resolving the optimal route problem.

Level Set Method Applied on Pseudo-compressibility Method for the Analysis of Two-phase Flow (Pseudo-compressibility 방법에서 이상유동 해석을 위한 Level Set방법의 적용)

  • Ihm Seung-Won;Kim Chongam;Shim Jae-Seol;Lee Dong-Young
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.17 no.3
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    • pp.158-165
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    • 2005
  • In order to analyze incompressible two-phase flow, Level Set method was applied on pseudo-compressibility formulation. Level Set function is defined as a signed distance function from the phase interface, and gives the information of the each phase location and the geometric data to the flow. In this study, Level Set function transport equation was coupled with flow conservation equations, and owing to pseudo-compressibility technique we could solve the resultant vector equation iteratively. Two-phase flow analysis code was developed on general curvilinear coordinate, and numerical tests of bubble dynamics and surging wave problems demonstrate its capability successfully.

Building More Secure Femtocell with Improved Proxy Signature (개선된 위임 서명 방식을 이용해서 더 안전한 펨토셀 환경 구축)

  • Choi, Hyoung-Kee;Han, Chan-Kyu;Kim, Seung-Ryong
    • Journal of the Korea Institute of Information Security & Cryptology
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    • v.24 no.1
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    • pp.75-86
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    • 2014
  • Demand for the femtocell is largely credited to the surge in a more always best connected communication conscious public. 3GPP defines new architecture and security requirement for Release 9 to deal with femtocell, Home eNode B referred as HeNB. In this paper, we analyze the HeNB security with respect to mutual authentication, access control, and secure key agreement. Our analysis pointed out that a number of security vulnerabilities have still not been addressed and solved by 3GPP technical specification. These include eavesdropping, man-in-the-middle attack, compromising subscriber access list, and masquerading as valid HeNB. To the best of our knowledge, any related research studying HeNB security was not published before. Towards this end, this paper proposes an improved authentication and key agreement mechanism for HeNB which adopts proxy-signature and proxy-signed proxy-signature. Through our elaborate analysis, we conclude that the proposed not only prevents the various security threats but also accomplishes minimum distance from use-tolerable authentication delay.

Tarsal switch using an anterior approach to correct severe ptosis

  • Meneghim, Roberta Lilian Fernandes de Sousa;Ferraz, Lucieni Barbarini;Galindo-Ferreiro, Alicia;Khandekar, Rajiv;Sanchez-Tocino, Hortensia;Schellini, Silvana
    • Archives of Plastic Surgery
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    • v.45 no.2
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    • pp.165-170
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    • 2018
  • Background To present the outcomes of the tarsal switch procedure using an anterior approach to correct severe ptosis with poor levator muscle function (<4 mm) with absent or poor Bell's phenomenon. Methods This retrospective case series included 11 patients with severe neurogenic or acquired myogenic palpebral ptosis. All patients underwent the tarsal switch procedure through an anterior approach from 2012 to 2015. Margin reflex distance (MRD1 and MRD2) and the palpebral fissure were evaluated preoperatively and postoperatively. Data were compared using the Wilcoxon signed-rank test. P-values <0.05 were considered to indicate statistical significance. Results Surgery was performed on 18 eyelids (11 patients). The median age at surgery was 57 years (range, 29-86 years). Four patients had unilateral ptosis and seven had bilateral ptosis. Nine patients had myogenic ptosis and two had neurogenic ptosis. Postoperatively, the chin-up position improved in all patients. The MRD1 increased statistically significantly, from 0 mm preoperatively to 1.0 mm postoperatively (P=0.001). The MRD2 decreased statistically significantly, from 4.5 mm preoperatively to 3.0 mm postoperatively (P=0.001). The palpebral fissure did not change (4.0 mm preoperatively to 4.0 mm postoperatively) (P=0.13). Conclusions The tarsal switch procedure through an anterior approach is an effective alternative for correcting severe ptosis, especially neurogenic or acquired myogenic ptosis. This procedure can be performed with minimal risk of ocular surface exposure and provides stable outcomes.