scholarly journals Estimation of Bottom Friction Coefficients Based on an Isopycnic-Coordinate Internal Tidal Model with Adjoint Method

2013 ◽  
Vol 2013 ◽  
pp. 1-11
Author(s):  
Yanqiu Gao ◽  
Anzhou Cao ◽  
Haibo Chen ◽  
Xianqing Lv
Keyword(s):  
Adjoint Method ◽  
Bottom Friction ◽  
Conical Surface ◽  
Friction Coefficients ◽  
Tidal Model ◽  
Good Ability ◽  
Point Scheme ◽  
Group 3 ◽  
Group 2 ◽  
Spatially Varying

Based on an isopycnic-coordinate internal tidal model with the adjoint method, three groups of ideal experiments are carried out in order to investigate the estimation of spatially varying bottom friction coefficients (BFCs). In group 1, five values of distance between independent points (DIP) are used to invert the BFCs with the distribution of conical surface. Results show that the BFCs can be inverted successfully with independent point scheme and the strategy with a DIP of 50′ can yield the best results. In group 2, five values of interpolation radius (IR) are used to invert the BFCs with the distribution of conical surface. Results show that the strategy with an IR of 1.9 times of DIP can yield the best results. Based on the results of the first two groups, group 3 adopts the optimal DIP and IR to estimate 4 kinds of spatially varying BFCs. The results indicate that the isopycnic-coordinate internal tidal model with the adjoint method has a good ability to estimate the spatially varying BFCs; the inversion results of the BFCs with the distribution of revolution paraboloid are better than those with the distribution of conical surface.

scholarly journals Estimation of Open Boundary Conditions Based on an Isopycnic-Coordinate Internal Tidal Model with Adjoint Assimilation Method

2013 ◽  
Vol 2013 ◽  
pp. 1-11 ◽  
Author(s):  
Yanqiu Gao ◽  
Guangzhen Jin ◽  
Haibo Chen ◽  
Xianqing Lv
Keyword(s):  
Boundary Conditions ◽  
Internal Tide ◽  
Open Boundary ◽  
Open Boundary Conditions ◽  
Tidal Model ◽  
Good Ability ◽  
Order Of Magnitude ◽  
Adjoint Assimilation ◽  
Spatially Varying ◽  
Group 1

The isopycnic-coordinate internal tidal model with adjoint assimilation method is developed into a three-layer version. Two groups of ideal experiments are carried out in order to investigate the estimation of spatially varying open boundary conditions (OBCs). In group 1, different independent point schemes (IPSs) are used to invert 6 kinds of prescribed distributions of OBCs. Results show that, after assimilation, the cost functions and their gradient norms are reduced by about 2 orders of magnitude and by about 1 order of magnitude, respectively; the mean absolute errors (MAEs) in OBCs and the vector differences of horizontal current are reduced by 1 order of magnitude and by more than 23.53% compared with the values before assimilation, respectively. The results demonstrate that the three-layered model has a good ability in estimating the spatially varying OBCs; the use of IPSs can effectively improve the estimation precision; fewer independent points are feasible when the distribution is simpler, and appropriately more independent points are required when the distribution is more complex. In group 2, by using the optimal IPSs in group 1, the model is also able to successfully invert the OBCs on a real topography in the Luzon Strait area. The results are important to the study of the internal tide in the South China Sea.

scholarly journals Estimation of Oceanic Eddy Viscosity Profile and Wind Stress Drag Coefficient Using Adjoint Method

2015 ◽  
Vol 2015 ◽  
pp. 1-11 ◽  
Author(s):  
Qilin Zhang ◽  
Yanqiu Gao ◽  
Xianqing Lv
Keyword(s):  
Eddy Viscosity ◽  
Adjoint Method ◽  
Regularization Parameter ◽  
Assimilation Efficiency ◽  
Step Length ◽  
Group 4 ◽  
Integral Time ◽  
Oceanic Eddy ◽  
Group 3 ◽  
Group 2

Adjoint method is used to assimilate pseudoobservations to simultaneously estimate the OEVP and the WSDC in an oceanic Ekman layer model. Five groups of experiments are designed to investigate the influences that the optimization algorithms, step-length, inverse integral time of the adjoint model, prescribed vertical distribution of eddy viscosity, and regularization parameter exert on the inversion results. Experimental results show that the best estimation results are obtained with the GD algorithm; the best estimation results are obtained when the step-length is equal to 1 in Group 2; in Group 3, 8 days of inverse integral time yields the best estimation results, and good assimilation efficiency is achieved by increasing iteration steps when the inverse integral time is reduced; in Group 4, the OEVP can be estimated for some specific distributions; however, when the VEVCs increase along with the depth at the bottom of water, the estimation results are relatively poor. For this problem, we use extrapolation method to deal with the VEVCs in layers in which the estimation results are poor; the regularization method with appropriate regularization parameter can indeed improve the experiment result to some extent. In all experiments in Groups 2-3, the WSDCs are inverted successfully within 100 iterations.

scholarly journals Application of Surface Spline Interpolation in Inversion of Bottom Friction Coefficients

2017 ◽  
Vol 34 (9) ◽  
pp. 2021-2028 ◽  
Author(s):  
Zheng Guo ◽  
Haidong Pan ◽  
Wei Fan ◽  
Xianqing Lv
Keyword(s):  
Bohai Sea ◽  
Spline Interpolation ◽  
Linear Interpolation ◽  
Bottom Friction ◽  
New Method ◽  
Practical Application ◽  
Friction Coefficients ◽  
Tidal Model ◽  
Surface Spline ◽  
Nonlinear Distribution

AbstractA new method for the inversion of bottom friction coefficients (BFCs) in a two-dimensional tidal model is proposed in this study. In this method, the field of BFCs is constructed by interpolating values at independent points using a surface spline. The surface spline interpolation has an advantage: that the constructed surface is smoother than the surface constructed by the traditionally used linear interpolation, which has unrealistic extrema. The method is validated in twin experiments where the prescribed nonlinear distribution of BFCs are better inverted with the surface spline interpolation. In practical experiments, the BFCs are inverted and the M2 tide in the Bohai Sea is simulated by assimilating the TOPEX/Poseidon (T/P) data. The small errors between the simulation results and the observations, as well as the accurate cotidal charts, demonstrate the feasibility of the new method in practical application.

scholarly journals Application of elastography of the shift wave in combination with transrectal biopsy in diagnosis of the prostatic gland diseases

2018 ◽  
Vol 85 (4) ◽  
pp. 28-31
Author(s):  
F. Z. Haiseniuk ◽  
S. V. Golovkо ◽  
О. F. Savitsky ◽  
V. М. Кravchuk
Keyword(s):  
Transrectal Ultrasound ◽  
Imaging Method ◽  
Transrectal Biopsy ◽  
Group 4 ◽  
Additional Imaging ◽  
Point Scheme ◽  
Group 3 ◽  
Group 2 ◽  
Prostatic Gland ◽  
Magnet Resonance

Objective. Determination of efficacy and informativity for method of a shift wave elastography (SWE) in a frame of prostatic gland cancer (PGC) diagnosis and characterization; elaboration of recommendations, concerning application of this method in general practice, revealing its faults and restrictions. Маterials and methods. The investigation was conducted, incorporating 31 patients, in the Urological Clinic of National Military–Medical Clinical Centre «ГВКГ». The patients were divided into 4 Groups: Group 1 (n=7) – a control one (conditionally healthy patients), Group 2 (n=8) – patients, suffering benign hyperplasia of prostatic gland, Group 3 (n=8) – patients, suffering chronic prostatitits, Group 4 (n=8) – patients, suffering PGC. In all the patients a transrectal ultrasound investigation (TRUI), using endocavital ЕС 6,5 MHz/10R transducer for SWE, was performed. In the patients Groups 2, 3, 4 a transrectal multifocal biopsy of pancreatic gland in accordance to standard 12–point scheme was done, and, additionally, – the suspicious foci biopsy, revealed in SWE. Results. In all the patients the data of histopathological investigation have correlated with the SWE results. Conclusion. SWE may serve as additional imaging method for prostatic gland, while examining patients, using conventional TRUI and magnet–resonance tomography.

scholarly journals Estimating Smoothly Varying Open Boundary Conditions for a 3D Internal Tidal Model with an Improved Independent Point Scheme

2018 ◽  
Vol 35 (6) ◽  
pp. 1299-1311 ◽  
Author(s):  
Dong Jiang ◽  
Haibo Chen ◽  
Guangzhen Jin ◽  
Xianqing Lv
Keyword(s):  
Boundary Conditions ◽  
Adjoint Method ◽  
Spline Interpolation ◽  
Northern South China Sea ◽  
Altimeter Data ◽  
Open Boundary ◽  
Open Boundary Conditions ◽  
Independent Point ◽  
Tidal Model ◽  
Point Scheme

AbstractAn improved independent point (IP) scheme was proposed to estimate the open boundary conditions (OBCs) for a 3D internal tidal model through assimilating the TOPEX/Poseidon (T/P) altimeter data. Under the assumption that the OBCs were spatially and smoothly varying, values at a set of independent points along the open boundary were inverted using the adjoint method and values at other points were interpolated by the spline method. The scheme was calibrated through idealized experiments where the M2 tidal constituent in the northern South China Sea was simulated. The OBCs can be successfully inverted with the improved scheme and were better in spatial smoothness than the results obtained with the Cressman interpolation when embedded in the IP scheme. Simulations in realistic domains showed that the errors between simulations and observations were smaller when the spline interpolation was employed instead of the Cressman interpolation. Three boundary conditions of spline interpolation were used in simulations in realistic domains, and the result of the periodic boundary condition had the smallest error compared with the first and second boundary conditions.

Morphological Changes in the Rat Granulosa Cell Surface During Differentiation Induced by Estradiol and Gonadotropins

1977 ◽  
Vol 35 ◽  
pp. 484-485
Author(s):  
P. Bagavandoss ◽  
JoAnne S. Richards ◽  
A. Rees Midgley
Keyword(s):  
Cell Surface ◽  
Granulosa Cell ◽  
Morphological Changes ◽  
Follicular Development ◽  
Female Rats ◽  
Functional Changes ◽  
Group 4 ◽  
Group 3 ◽  
Group 5 ◽  
Group 2

During follicular development in the mammalian ovary, several functional changes occur in the granulosa cells in response to steroid hormones and gonadotropins (1,2). In particular, marked changes in the content of membrane-associated receptors for the gonadotropins have been observed (1).We report here scanning electron microscope observations of morphological changes that occur on the granulosa cell surface in response to the administration of estradiol, human follicle stimulating hormone (hFSH), and human chorionic gonadotropin (hCG).Immature female rats that were hypophysectcmized on day 24 of age were treated in the following manner. Group 1: control groups were injected once a day with 0.1 ml phosphate buffered saline (PBS) for 3 days; group 2: estradiol (1.5 mg/0.2 ml propylene glycol) once a day for 3 days; group 3: estradiol for 3 days followed by 2 days of hFSH (1 μg/0.1 ml) twice daily, group 4: same as in group 3; group 5: same as in group 3 with a final injection of hCG (5 IU/0.1 ml) on the fifth day.

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