34 research outputs found
A multiscale method applied to shallow water flow
A flux-limited second order scheme with the C-property is used to solve the one dimensional or two dimensional Saint-Venant system for shallow water flows with non-flat bottom and friction terms, as is introduced in [7] G. Haro, Numerical simulation of shallow water equations amd some physical models in image processing. Ph.D.Thesis, Departament of Technologies, Universitat Pompeu Fabra, Barcelona, 2005.
High resolution at low cost can be obtained by applying a point-value multiresolution transform [2, 3, 9] in order to detect regions with singularities. The above method is applied in these regions, while a cheap polynomial interpolation is used in the smooth zones, thus lowering the computational cost
High Resolution Schemes for Conservation Laws With Source Terms.
This memoir is devoted to the study of the numerical treatment of
source terms in hyperbolic conservation laws and systems. In particular,
we study two types of situations that are particularly delicate from
the point of view of their numerical approximation: The case of balance
laws, with the shallow water system as the main example, and the case of
hyperbolic equations with stiff source terms.
In this work, we concentrate on the theoretical foundations of highresolution
total variation diminishing (TVD) schemes for homogeneous
scalar conservation laws, firmly established. We analyze the properties
of a second order, flux-limited version of the Lax-Wendroff scheme which
avoids oscillations around discontinuities, while preserving steady states.
When applied to homogeneous conservation laws, TVD schemes prevent
an increase in the total variation of the numerical solution, hence guaranteeing
the absence of numerically generated oscillations. They are successfully
implemented in the form of flux-limiters or slope limiters for
scalar conservation laws and systems. Our technique is based on a flux
limiting procedure applied only to those terms related to the physical
flow derivative/Jacobian. We also extend the technique developed by Chiavassa
and Donat to hyperbolic conservation laws with source terms and
apply the multilevel technique to the shallow water system.
With respect to the numerical treatment of stiff source terms, we take
the simple model problem considered by LeVeque and Yee. We study
the properties of the numerical solution obtained with different numerical
techniques. We are able to identify the delay factor, which is responsible
for the anomalous speed of propagation of the numerical solution
on coarse grids. The delay is due to the introduction of non equilibrium values through numerical dissipation, and can only be controlled
by adequately reducing the spatial resolution of the simulation.
Explicit schemes suffer from the same numerical pathology, even after reducing
the time step so that the stability requirements imposed by the
fastest scales are satisfied. We study the behavior of Implicit-Explicit
(IMEX) numerical techniques, as a tool to obtain high resolution simulations
that incorporate the stiff source term in an implicit, systematic,
manner
Adaptive multiple crossover genetic algorithm to solve workforce scheduling and routing problem
The Workforce Scheduling and Routing Problem refers to the assignment of personnel to visits, across various geographical locations. Solving this problem demands tackling numerous scheduling and routing constraints while aiming to minimise the operational cost. One of the main obstacles in designing a genetic algorithm for this problem is selecting the best set of operators that enable better performance in a Genetic Algorithm (GA). This paper presents an adaptive multiple crossover genetic algorithm to tackle the combined setting of scheduling and routing problems. A mix of problem-specific and traditional crossovers are evaluated by using an online learning process to measure the operator's effectiveness. Best performing operators are given high application rates and low rates are given to the worse performing ones. Application rates are dynamically adjusted according to the learning outcomes in a non-stationary environment. Experimental results show that the combined performances of all the operators works better than using one operator in isolation. This study makes a contribution to advance our understanding of how to make effective use of crossover operators on this highly-constrained optimisation problem
Max–min dispersion with capacity and cost for a practical location problem
Diversity and dispersion problems deal with selecting a subset of elements from a given set in such a way that their diversity is maximized. This study considers a practical location problem recently proposed in the context of max–min dispersion models. It is called the generalized dispersion problem, and it models realistic applications by introducing capacity and cost constraints. We propose two effective linear formulations for this problem, and develop a hybrid metaheuristic algorithm based on the variable neighborhood search methodology, to solve real instances. Extensive numerical computational experiments are performed to compare our hybrid metaheuristic with the state-of-art heuristic, and with integer linear programming formulations (ILP). Results on public benchmark instances show the superiority of our proposal with respect to the previous algorithms. Our extensive experimentation reveals that ILP models are able to optimally solve medium-size instances with the Gurobi optimizer, although metaheuristics outperform ILP both in running time and quality in large-size instances
Enhancement of photoactivity and cellular uptake of (Bu4N)2[Mo6I8(CH3COO)6] complex by loading on porous MCM-41 support. Photodynamic studies as an anticancer agent
The incorporation by ionic assembly of the hexanuclear molybdenum cluster (Bu4N)2[Mo6I8(CH3CO2)6] (1) in amino-decorated mesoporous silica nanoparticles MCM-41, has yielded the new molybdenum-based hybrid photosensitizer 1@MCM-41. The new photoactive material presents a high porosity, due to the intrinsic high specific surface area of MCM-41 nanoparticles (989 m2 g-1) which is responsible for the good dispersion of the hexamolybdenum clusters on the nanoparticles surface, as observed by STEM analysis. The hybrid photosensitizer can generate efficiently singlet oxygen, which was demonstrated by using the benchmark photooxygenation reaction of 9,10-anthracenediyl-bis(methylene)dimalonic acid (ABDA) in water. The photodynamic therapy activity has been tested using LED light as an irradiation source (λirr ~ 400-700 nm; 15.6 mW/cm2). The results show a good activity of the hybrid photosensitizer against human cervical cancer (HeLa) cells, reducing up to 70 % their viability after 20 min of irradiation, whereas low cytotoxicity is detected in the darkness. The main finding of this research is that the incorporation of molybdenum complexes at porous MCM-41 supports enhances their photoactivity and improves cellular uptake, compared to free clusters.Ministerio de Ciencia, Innovación y Universidades of Spain (grant RTI2018-101675-B-I00) is acknowledged. F.G. thanks Universitat Jaume I (grant UJI-B2021-51) for the financial support. R.M.-M. laboratory members thank the financial support from the Spanish Government (project RTI2018-100910-B-C41) and the Generalitat Valenciana (project PROMETEO 2018/024). The research was supported by the Ministry of Science and Higher Education of the Russian Federation (M.N.S.). C.T. acknowledges the Generalitat Valenciana for her postdoctoral fellowship (APOSTD/2019/121). R.G. thanks Universitat Jaume I for a postdoctoral fellowship (POSTDOC-B/2018/09). We would like to thank Prof. Iván Mora-Seró (INAM-UJI) for the singlet oxygen phosphorescence measurements. The help of Jean Colombari in the final phase of this work is also recognized. SCIC-UJI is acknowledged for the technical support
A new well-balanced non-oscillatory central scheme for the shallow water equations on rectangular meshes
This paper is concerned with the development of high-order well-balanced central schemes to solve the shallow water equations in two spatial dimensions. A Runge Kutta scheme is applied for time discretization. A Gaussian quadrature rule is used to evaluate time integrals and a three-degree polynomial which calculates point-values or flux values.
A new procedure has been defined to evaluate the flux integrals and to approach the 2D
source term integrals in order to verify the exact C-property, using the water surface elevation instead of the water depth as a variable. Numerical experiments have confirmed the high-resolution properties of our numerical scheme in 2D test problems.This work was partially funded by the "Programa de Apoyo a la Investigacion y Desarrollo" (PAID-06-10) and (PAID-05-12) of the Universidad Politecnica de Valencia. Angel Balaguer-Beser thanks the support of the Spanish Ministry of Education and Science in the framework of the Projects CGL2009-14220-C02-01 and CGL2010-19591. The authors express their gratitude to the anonymous reviewers for their helpful comments.Capilla Romá, MT.; Balaguer Beser, ÁA. (2013). A new well-balanced non-oscillatory central scheme for the shallow water equations on rectangular meshes. Journal of Computational and Applied Mathematics. 252:62-74. https://doi.org/10.1016/j.cam.2013.01.014S627425
Anchoring gated mesoporous silica particles to ethylene vinyl alcohol films for smart packaging applications
[EN] This work is a proof of concept for the design of active packaging materials based on the anchorage of gated mesoporous silica particles with a pH triggering mechanism to a packaging film surface. Mesoporous silica micro- and nanoparticles were loaded with rhodamine B and functionalized with N-(3-trimethoxysilylpropyl)diethylenetriamine. This simple system allows regulation of cargo delivery as a function of the pH of the environment. In parallel, poly(ethylene-co-vinyl alcohol) films, EVOH 32 and EVOH 44, were ultraviolet (UV) irradiated to convert hydroxyl moieties of the polymer chains into -COOH functional groups. The highest COOH surface concentration was obtained for EVOH 32 after 15 min of UV irradiation. Anchoring of the gated mesoporous particles to the films was carried out successfully at pH 3 and pH 5. Mesoporous particles were distributed homogeneously throughout the film surface and in greater concentration for the EVOH 32 films. Films with the anchored particles were exposed to two liquid media simulating acidic food and neutral food. The films released the cargo at neutral pH but kept the dye locked at acidic pH. The best results were obtained for EVOH 32 irradiated for 15 min, treated for particle attachment at pH 3, and with mesoporous silica nanoparticles. This opens the possibility of designing active materials loaded with antimicrobials, antioxidants, or aromatic compounds, which are released when the pH of the product approaches neutrality, as occurs, for instance, with the release of biogenic amines from fresh food products.This research was funded by the Ministry of Economy, Industry, and Competitiveness, projects AGL2015-64595-R, AGL2015-70235-C2-1-R, and AGL2015-70235-C2-2-R.Muriel-Galet, V.; Pérez-Esteve, É.; Ruiz Rico, M.; Martínez-Máñez, R.; Barat Baviera, JM.; Hernandez-Muñoz, P.; Gavara Clemente, R. (2018). Anchoring gated mesoporous silica particles to ethylene vinyl alcohol films for smart packaging applications. Nanomaterials. 8(10). https://doi.org/10.3390/nano8100865S81
Cardiac magnetic resonance outperforms echocardiography to predict subsequent implantable cardioverter defibrillator therapies in ST-segment elevation myocardial infarction patients
Altres ajuts: Conselleria de Educación-Generalitat Valenciana (PROMETEO/2021/008); Sociedad Española de Cardiología (Grant SEC/FEC-INVCLI 21/024)Implantable cardioverter defibrillators (ICD) are effective as a primary prevention measure of ventricular tachyarrhythmias in patients with ST-segment elevation myocardial infarction (STEMI) and depressed left ventricular ejection fraction (LVEF). The implications of using cardiac magnetic resonance (CMR) instead of echocardiography (Echo) to assess LVEF prior to the indication of ICD in this setting are unknown. We evaluated 52 STEMI patients (56.6 ± 11 years, 88.5% male) treated with ICD in primary prevention who underwent echocardiography and CMR prior to ICD implantation. ICD implantation was indicated based on the presence of heart failure and depressed LVEF (≤ 35%) by echocardiography, CMR, or both. Prediction of ICD therapies (ICD-T) during follow-up by echocardiography and CMR before ICD implantation was assessed. Compared to echocardiography, LVEF was lower by cardiac CMR (30.2 ± 9% vs. 37.4 ± 7.6%, p < 0.001). LVEF ≤ 35% was detected in 24 patients (46.2%) by Echo and in 42 (80.7%) by CMR. During a mean follow-up of 6.1 ± 4.2 years, 10 patients received appropriate ICD-T (3.16 ICD-T per 100 person-years): 5 direct shocks to treat very fast ventricular tachycardia or ventricular fibrillation, 3 effective antitachycardia pacing (ATP) for treatment of ventricular tachycardia, and 2 ineffective ATP followed by shock to treat ventricular tachycardia. Echo-LVEF ≤ 35% correctly predicted ICD-T in 4/10 (40%) patients and CMR-LVEF ≤ 35% in 10/10 (100%) patients. CMR-LVEF improved on Echo-LVEF for predicting ICD-T (area under the curve: 0.76 vs. 0.48, p = 0.04). In STEMI patients treated with ICD, assessment of LVEF by CMR outperforms Echo-LVEF to predict the subsequent use of appropriate ICD therapies
Changes in humoral immune response after SARS-CoV-2 infection in liver transplant recipients compared to immunocompetent patients
The protective capacity and duration of humoral immunity after SARS-CoV-2 infection are not yet understood in solid organ transplant recipients. A prospective multicenter study was performed to evaluate the persistence of anti-nucleocapsid IgG antibodies in liver transplant recipients 6 months after coronavirus disease 2019 (COVID-19) resolution. A total of 71 liver transplant recipients were matched with 71 immunocompetent controls by a propensity score including variables with a well-known prognostic impact in COVID-19. Paired case-control serological data were also available in 62 liver transplant patients and 62 controls at month 3 after COVID-19. Liver transplant recipients showed a lower incidence of anti-nucleocapsid IgG antibodies at 3 months (77.4% vs. 100%, p <.001) and at 6 months (63.4% vs. 90.1%, p <.001). Lower levels of antibodies were also observed in liver transplant patients at 3 (p =.001) and 6 months (p <.001) after COVID-19. In transplant patients, female gender (OR = 13.49, 95% CI: 2.17-83.8), a longer interval since transplantation (OR = 1.19, 95% CI: 1.03-1.36), and therapy with renin-angiotensin-aldosterone system inhibitors (OR = 7.11, 95% CI: 1.47-34.50) were independently associated with persistence of antibodies beyond 6 months after COVID-19. Therefore, as compared with immunocompetent patients, liver transplant recipients show a lower prevalence of anti-SARS-CoV-2 antibodies and more pronounced antibody levels decline
El moviment coral a la província de Castelló
Aquest article tracta dels antecedents i l’evolució cronològica del moviment coral a la província
de Castelló al llarg de la història, des del naixement de la primera societat coral de l’Estat Espanyol
i la influencia directa de la mateixa a la província amb la creació de la primera entitat del País
Valencià, la Sociedad Coral El Maestrazgo de Vinaròs al 1862, fins l’actualitat