Determinants of Bilateral Trade Flows Between Vietnam and Trading Partner Countries – Gravity Model Approach

This study uses the gravity model to investigate the bilateral trade flows between Vietnam and 52 countries from 2001 through 2011. The data are collected from International Trade Centre (ITC), International Monetary Fund (IMF), and the World Bank (WB). The results show that economic size, geographical distance, economic distance, technological innovation, trade openness, free trade agreement, population, exchange rate, and common border affect the bilateral trade flows between Vietnam and these 52 countries. More importantly, this study uses the speed-of-convergence method to find new potential trading partners for Vietnam, such as those in Africa and Southwest Asia.

181 Impact of leaflet-tethering angle correction on the assessment of tricuspid regurgitation severity using the PISA method

Aims Severe tricuspid regurgitation (TR) is associated with excess mortality and morbidity. Therefore, accurate assessment of TR severity is pivotal. In clinical routine, the calculation of the effective regurgitant orifice area (EROA) and the regurgitant volume (RVol) using flow convergence method (PISA) by echocardiography are among the recommended parameters to define TR severity. However, the distortion of the proximal convergence zone related to the extent of valve leaflet tethering may result in smaller PISA radius and in underestimation of TR severity. Correcting for the angle of the leaflet tethering could reduce errors due to geometric assumption of a flat valvular plane and improve the accuracy of the calculations. The aims of our study were: (1) to evaluate whether taking into account the extent of leaflet tethering by applying the angle correction (AC) in the PISA formula improves the accuracy of the quantitative assessment of TR severity; (2) to assess the potential clinical impact of AC. Methods and results Forty-one patients with functional TR (73.5 ± 11.8 years, 51% men, 36% sinus rhythm, 17% severe), underwent 2D and 3D echocardiography. We compared the RVol obtained by volumetric method (as reference) with the RVol by PISA with and without AC. TR RVol by volumetric method was calculated as: total RV stroke volume (RV SV)–left ventricular forward SV (LV SV), where RV SV was obtained by subtracting the end-systolic from end-diastolic RV volume measured by 3D echocardiography and LV SV was calculated by multiplying LV outflow area by velocity time integral (VTI). TR RVol by PISA was calculated as EROA × VTI TR. Uncorrected EROA was calculated using the formula: 6.28 r2 × Va/PeakV TR (r—PISA radius, Va, aliasing velocity, PeakV TR—TR peak velocity). The corrected EROA accounting for the PISA geometric distortion by leaflet tethering angle (α) was calculated as: 6.28 r2 × Va (α/180)/PeakV TR (PISAAC), where α was measured using a protractor generated by dedicated software. PISA radius and angle were 5.5 ± 1.97 mm and 211.2° ± 13.6°, respectively. Application of AC to PISA method resulted in larger EROA and RVol (0.34 ± 0.38 cm2 vs. 0.24 ± 0.24 cm2 and, 25.2 ± 19.3 ml vs. 18.6 ± 13.1 ml, respectively). The percentage change in EROAAC was over 40%. When compared to the volumetric method, RVol by corrected PISA method was significantly closer and correlated (bias −3.95 ml, LOA ± 6.41 ml, r = 0.987; P < 0.001) than the conventional PISA without AC (bias −10.5 ml, LOA ± 15 ml, r = 0.975). Angle correction resulted in a change of TR severity in 32% of cases and in a greater concordance of TR severity grade with the volumetric method (75%, 31/41 with AC vs. 52%, 22/41 without AC). Conclusions Angle-corrected PISA method that accounts for the extent of the leaflet tethering in TR provided significantly larger TR RVol that were closely correlated with the volumetric RVol by 3D echocardiography. A simple geometric angle correction of the proximal flow with PISA method reclassified up to one-third of patients with functional TR.

Large deviation principles of 2D stochastic Navier–Stokes equations with Lévy noises

Taking the consideration of two-dimensional stochastic Navier–Stokes equations with multiplicative Lévy noises, where the noises intensities are related to the viscosity, a large deviation principle is established by using the weak convergence method skillfully, when the viscosity converges to 0. Due to the appearance of the jumps, it is difficult to close the energy estimates and obtain the desired convergence. Hence, one cannot simply use the weak convergence approach. To overcome the difficulty, one introduces special norms for new arguments and more careful analysis.

Evaluating the thickness of thin-bed seams using seismic data on the example of the Tula-Bobrikovian sediments in the Republic of Tatarstan

Background. Determining the productive deposit thickness is of fundamental importance for assessing the reserves of oil and gas fields. 3D seismic data is used to assess the thickness of seams in the interwell space. However, owing to the limited vertical resolution of seismic data, estimating thicknesses of thin deposits (less than 20 m) is challenging.Aim. To evaluate different approaches to calculating the thickness of the productive deposits based on seismic data with the purpose of selecting the most optimal approach.Materials and methods. We compared the results obtained using different approaches to assessing the productive deposit thickness of the Tula-Bobrikovian age in the interwell space, including the convergence method (calculating the thickness for oilwells with no seismic data used), the use of seismic attributes to calculate the “seismic attribute — reservoir thickness” dependency (for attributes, dominant frequency and mono-frequency component at 60 Hz), estimation of the thickness from the seismic signal shape. Cokriging was used to calculate inferred power maps from seismic attribute data and to classify them by waveform. For each of the techniques, the crossvalidation method and calculating the root-mean-square deviation were used as quality criteria.Results. When assessing the accuracy of thickness map development, the root-mean-square deviation was 12.3 m according to convergence method, 10.2 m — to the dominant frequency attribute, 7.2 m — to the attribute of the monofrequency component at 60 Hz and 6.3 m — to the signal shape classification. The latter method yielded the best results, and the developed thickness map allowed paleo-cut to be traced.Conclusions. Applying the thickness estimation method based on the seismic signal shape allows the value of the root-mean-square deviation to be reduced by a factor of 2 compared to that of the widely adopted convergence method. This approach permits productive deposits thickness to be more accurately estimated and hydrocarbon reserves to be determined.

Large deviation principles for a 2D stochastic Allen–Cahn–Navier–Stokes driven by jump noise

In this paper, we derive a large deviation principle for a stochastic 2D Allen–Cahn–Navier–Stokes system with a multiplicative noise of Lévy type. The model consists of the Navier–Stokes equations for the velocity, coupled with a Allen–Cahn system for the order (phase) parameter. The proof is based on the weak convergence method introduced in [A. Budhiraja, P. Dupuis and V. Maroulas, Variational representations for continuous time processes, Ann. Inst. Henri Poincarà ⓒ Probab. Stat. 47(3) (2011) 725–747].

The non-Lipschitz stochastic Cahn–Hilliard–Navier–Stokes equations in two space dimensions

The stochastic two-dimensional Cahn–Hilliard–Navier–Stokes equations under non-Lipschitz conditions are considered. This model consists of the Navier–Stokes equations controlling the velocity and the Cahn–Hilliard model controlling the phase parameters. By iterative techniques, a priori estimates and weak convergence method, the existence and uniqueness of an energy weak solution to the equations under non-Lipschitz conditions have been obtained.

Recent Meta-heuristic Algorithms with a Novel Premature Covergence Method for Determining the Parameters of PV Cells and Modules

Currently, the incorporation of solar panels in many applications is a booming trend, which necessitates accurate simulations and analysis of their performance under different operating conditions for further decision making. In this paper, various optimization algorithms are addressed comprehensively through a comparative study and further discussions for extracting the unknown parameters. Efficient use of the iterations within the optimization process may help meta-heuristic algorithms in accelerating convergence plus attaining better accuracy for the final outcome. In this paper, a method, namely, the premature convergence method (PCM), is proposed to boost the convergence of meta-heuristic algorithms with significant improvement in their accuracies. PCM is based on updating the current position around the best-so-far solution with two-step sizes: the first is based on the distance between two individuals selected randomly from the population to encourage the exploration capability, and the second is based on the distance between the current position and the best-so-far solution to promote exploitation. In addition, PCM uses a weight variable, known also as a controlling factor, as a trade-off between the two-step sizes. The proposed method is integrated with three well-known meta-heuristic algorithms to observe its efficacy for estimating efficiently and effectively the unknown parameters of the single diode model (SDM). In addition, an RTC France Si solar cell, and three PV modules, namely, Photowatt-PWP201, Ultra 85-P, and STM6-40/36, are investigated with the improved algorithms and selected standard approaches to compare their performances in estimating the unknown parameters for those different types of PV cells and modules. The experimental results point out the efficacy of the PCM in accelerating the convergence speed with improved final outcomes.

Convergence of Newton Raphson Method and its Variants

In Numerical Analysis and various uses, including operation testing and processing, Newton’s method may be a fundamental technique. We research the history of the methodology, its core theories, the outcomes of integration, changes, they’re worldwide actions. We consider process implementations for various groups of optimization issues, like unrestrained optimization, problems limited by equality, convex programming, and methods for interior points. Some extensions are quickly addressed (non-smooth concerns, continuous analogue, Smale’s effect, etc.), whereas some others are presented in additional depth (e.g., variations of the worldwide convergence method). The numerical analysis highlights the quicker convergence of Newton’s approach obtained with this update. This updated sort of Newton-Raphson is comparatively straightforward and reliable; it’d be more probable to converge into an answer than either the upper order strategies (4th and 6th degree) or the tactic of Newton itself. Our dissertation could be about the Convergence of the Newton-Raphson Method which is a way to quickly find an honest approximation for the basis of a real-valued function g(m) = 0. The derivation of the Newton Raphson formula, examples, uses, advantages, and downwards of the Newton Raphson Method has also been discussed during this dissertation.