• Title/Summary/Keyword: Dynamical Consistency

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Diagnosis of Linear Systems with Structured Uncertainties based on Guaranteed State Observation

  • Planchon, Philippe;Lunze, Jan
    • International Journal of Control, Automation, and Systems
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    • v.6 no.3
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    • pp.306-319
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    • 2008
  • Reaching fault tolerance in technological systems requires to detect malfunctions. This paper presents a diagnostic method that is robust with respect to unknown-but-bounded uncertainties of the dynamical model and the measurements. By using models of the faultless and the faulty behaviours, a state-set observer computes polyhedral sets from which the consistency of the models with the interval measurements is determined. The diagnostic result is proven to be complete, i.e., the set of faults obtained by the diagnostic algorithm includes the actual fault. The algorithm is illustrated by an application example.

The Structure of Optimal Tariff Levied on Non-Renewable Resource : A Dynamic Approach (비재생자원 수입관세의 동태적 구조에 관한 연구)

  • Lee, Dug Man;Lee, Young Hwan
    • Environmental and Resource Economics Review
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    • v.14 no.1
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    • pp.221-235
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    • 2005
  • In this paper, we analyzed the dynamic structure of optimal tariff levied on importing non-renewable resources such as petroleum, iron, coal, etc. According to the previous literature that have studied this objective, the time inconsistent open loop tariff has been suggested to be imposed in order to improve the welfare level of importing country. We set up the efficient model to identify how to impose the optimal tariff over time. Based on this model, we have found that the previous literature ignored that the costate variable for the stock for non-renewable resource decomposed between the scarcity effect and the cost effect. On the basis of the role of costate variable, we, however, have found that the proposition of the previous literature has led into errors. Hence, we suggest that the dynamically consistent open loop tariff for non-renewable resources would improve the welfare level of importing country.

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Modern Sedimentary Environments Within the Gogunsan Archipelago (고군산군도 내측해역의 현생퇴적환경)

  • Lee, Hee-Jun;Kim, Min-Ji;Kim, Tae-Kyung
    • Ocean and Polar Research
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    • v.30 no.4
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    • pp.519-536
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    • 2008
  • The relatively tranquil area within the Gogunsan Archipelago was for the first time investigated preliminarily with respect to modern sedimentological processes in association with the emplacement of the Saemangeum Dyke. Basic sedimentological observations, bathymetry and surface sediments were performed twice during 2006-2008 to compare the results and elaborate changes during that period of time. In addition, sediment dynamical observations were carried out with latest measuring equipment along two transects crossing the entrances of the archipelago, including 12-hour onboard measurements of current, suspended sediments, temperature, and salinity. This dataset was used to reveal hydrodynamic characteristics for spring season April-May and to estimate the direction and relative magnitude of the net flux of suspended sediments. There occurred three depositional areas (A to C) within the archipelago, where sediment texture was also changed. In area A, around Yami Island and the dyke, and area B, in the center of the archipelago, surface sediments became coarsened over the two-year period; sand content increased 5% at the expense of silt content in the former, whereas silt content increased 3% at the expense of clay content in the latter. By comparison, area C in the western entrance of the archipelago shows a textural trend of fining with more silt and clay (combined increase of 5%) at the expense of sand content. The accumulation of sediments in areas A and B is attributable to the sand and silt resuspended from the seabed sediments off sector 4 of the dyke during the winter. The origin of the fine materials depositing on area C is uncertain at present, although suspended sediments moving offshore around the archipelago may be one of the most likely candidates for the source. The temperature of seawater increased rapidly from $9-10^{\circ}C$ in April to $14-16^{\circ}C$ in May, whereas salinity remained more or less constant at 31-32%o during the two months. Both of these parameters showed little variations with depth through a tidal cycle, suggesting good mixing of seawater without any help of significant waves. The consistency of salinity during a tidal cycle also indicates no insignificant effects of freshwater from the rivers Mangyung and Donjin emitting through the opening gap near Sinsi Island. The suspended sediment concentrations were higher at the entrance between Sunyu and Sinsi islands than at the entrance between Hoenggyong and Sinsi islands, ranging from 20 and 30 mg/l and from 5 and 15 mg/l, respectively at the sea surface. Although tidal currents were variable across a transect between Sunyu and Sinsi islands, the currents across the entrance between Hoenggyong and Sinsi islands flowed consistently in the same direction all over the transect during a tidal cycle. The estimation of net flux of suspended sediments indicates that suspended sediments are transferred to the Gogunsan Archipelago mainly through a relatively deep trough adjacent to Sinsi Island toward the shallow area around Yami Island and the dyke.

A Study of Global Ocean Data Assimilation using VAF (VAF 변분법을 이용한 전구 해양자료 동화 연구)

  • Ahn, Joong-Bae;Yoon, Yong-Hoon;Cho, Eek-Hyun;Oh, He-Ram
    • The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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    • v.10 no.1
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    • pp.69-78
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    • 2005
  • ARCO and TAO data which supply three dimensional global ocean information are assimilated to the background field from a general circulation model, MOM3. Using a variational Analysis using Filter (VAF), which is a spatial variational filter designed to reduce computational time and space efficiently and economically, observed ARGO and TAO data are assimilated to the OGCM-generated background sea temperature for the generation of initial condition of the model. For the assessment of the assimilation impact, a comparative experiment has been done by integrating the model from different intial conditions: one from ARGO-, TAO-data assimilated initial condition and the other from background state without assimilation. The assimilated analysis field not only depicts major oceanic features more realistically but also reduces several systematic model bias that appear in every current OGCMs experiments. From the 10-month of model integrations with and without assimilated initial conditions, it is found that the major assimilated characteristics in sea temperature appeared in the initial field remain persistently throughout the integration. Such implies that the assimilated characteristics of the reduced sea temperature bias is to last in the integration without rapid restoration to the non-assimilated OGCM integration state by dispersing mass field in the form of internal gravity waves. From our analysis, it is concluded that the data assimilation method adapted in this study to MOM3 is reasonable and applicable with dynamical consistency. The success in generating initial condition with ARGO and TAO data assimilation has significant implication upon the prediction of the long-term climate and weather using ocean-atmosphere coupled model.

Avoidance of Internal Resonances in Hemispherical Resonator Assemblies from Fused Quartz Connected by Indium Solder

  • Sarapuloff, Sergii A.;Rhee, Huinam;Park, Sang-Jin
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2013.04a
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    • pp.835-841
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    • 2013
  • Modern solid-state gyroscopes (HRG) with hemispherical resonators from high-purity quartz glass and special surface superfinishing and ultrathin gold coating become the best instruments for precise-grade inertial reference units (IRU) targeting long-term space missions. Designing of these sensors could be a notable contribution into development of Korea as a space nation. In participial, 40mm diameter thin-shell resonator from high-purity fused quartz, fabricated as a single-piece with its supporting stem has been designed, machined, etched, tuned, tested, and delivered by STM Co. (ATS of Ukraine) several years ago; an extremely-high Q-factor (upto 10~20 millions) has been shown. Understanding of the best way how to match such a unique sensor with inner glass assembly of the gyro means how to use the high potential in a maximal extent; and this has become the urgent task. Inner quartz glass assembly has a very thin indium (In) layer soldered the resonator and its silica base (case), but effects of internal resonances between operational modal pair of the shell-cup and its side (parasitic) modes can notable degrade the potential of the sensor as a whole, instead of so low level of resonator's intrinsic losses. Unfortunately, there are special combinations of dimensions of the parts (so-called, "resonant sizes"), when intensive losses of energy occurs. The authors proposed to use the length of stem's fixture as an additional design parameter to avoid such cases. So-called, a cyclic scheme of finite element method (FEM) and ANSYS software were employed to estimate different combinations of gyro assembly parameters. This variant has no mismatches of numerical origin due to FEM's discrete mesh. The optimum length and dangerous "resonant lengths" have been found. The special attention has been paid to analyses of 3D effects in a cup-stem transient zone, including determination of a difference between the positions of geometrical Pole of the resonant hemisphere and of its "dynamical Pole", i.e., its real zone of oscillation node. Boundary effects between the shell (cup) and 3D short "beams" (inner and outer stems) have been ranged. The results of the numerical experiments have been compared with the classic model of a quasi-hemispherical shell band with inextensional midsurface, and the solution using Rayleigh's functions of the $1^{st}$ and $2^{nd}$ kinds. To guarantee the truth of the recommended sizes to a designer of the real device, the analytical and FEM results have been compared with experimental data for a party of real resonators. The consistency of the results obtained by different means has been shown with errors less than 5%. The results notably differ from the data published earlier by different researchers.

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