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排序方式: 共有332条查询结果,搜索用时 343 毫秒
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Sinuo Liu Xiaokun Wang Xiaojuan Ban Yanrui Xu Jing Zhou Jií Kosinka Alexandru C. Telea 《Computer Graphics Forum》2021,40(1):54-67
A major issue in smoothed particle hydrodynamics (SPH) approaches is the numerical dissipation during the projection process, especially under coarse discretizations. High‐frequency details, such as turbulence and vortices, are smoothed out, leading to unrealistic results. To address this issue, we introduce a vorticity refinement (VR) solver for SPH fluids with negligible computational overhead. In this method, the numerical dissipation of the vorticity field is recovered by the difference between the theoretical and the actual vorticity, so as to enhance turbulence details. Instead of solving the Biot‐Savart integrals, a stream function, which is easier and more efficient to solve, is used to relate the vorticity field to the velocity field. We obtain turbulence effects of different intensity levels by changing an adjustable parameter. Since the vorticity field is enhanced according to the curl field, our method can not only amplify existing vortices, but also capture additional turbulence. Our VR solver is straightforward to implement and can be easily integrated into existing SPH methods. 相似文献
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Popa Iolanda V. Burlacu Alexandru Gavrilescu Otilia Dranga Mihaela Prelipcean Cristina Cijevschi Mihai Cătălina 《Neural computing & applications》2021,33(21):14133-14146
Neural Computing and Applications - Colonoscopy is the “gold” standard for evaluating disease activity in ulcerative colitis (UC). An important area of research is finding a... 相似文献
4.
Bianca Stoean Dumitrita Rugina Monica Focsan Ana-Maria Craciun MÎdÎlina Nistor Tamas Lovasz Alexandru Turza Ioan-Dan Porumb Emese Gl Castelia Cristea Luminita Silaghi-Dumitrescu Simion Astilean Luiza Ioana Gaina 《International journal of molecular sciences》2021,22(6)
We report here the synthesis and structural characterization of novel cationic (phenothiazinyl)vinyl-pyridinium (PVP) dyes, together with optical (absorption/emission) properties and their potential applicability as fluorescent labels. Convective heating, ultrasound irradiation and mechanochemical synthesis were considered as alternative synthetic methodologies proficient for overcoming drawbacks such as long reaction time, nonsatisfactory yields or solvent requirements in the synthesis of novel dye (E)-1-(3-chloropropyl)-4-(2-(10-methyl-10H-phenothiazin-3-yl)vinyl)pyridin-1-ium bromide 3d and its N-alkyl-2-methylpyridinium precursor 1c. The trans geometry of the newly synthesized (E)-4-(2-(7-bromo-10-ethyl-10H-phenothiazin-3-yl)vinyl)-1-methylpyridin-1-ium iodide 3b and (E)-1-methyl-4-(2-(10-methyl-10H-phenothiazin-3-yl)vinyl)pyridin-1-ium tetrafluoroborate 3a′ was confirmed by single crystal X-ray diffraction. A negative solvatochromism of the dyes in polar solvents was highlighted by UV-Vis spectroscopy and explanatory insights were supported by molecular modeling which suggested a better stabilization of the lowest unoccupied molecular orbitals (LUMO). The photostability of the dye 3b was investigated by irradiation at 365 nm in different solvents, while the steady-state and time-resolved fluorescence properties of dye 3b and 3a′ in solid state were evaluated under one-photon excitation at 485 nm. The in vitro cytotoxicity of the new PVP dyes on B16-F10 melanoma cells was evaluated by WST-1 assay, while their intracellular localization was assessed by epi-fluorescence conventional microscopy imaging as well as one- and two-photon excited confocal fluorescence lifetime imaging microscopy (FLIM). PVP dyes displayed low cytotoxicity, good internalization inside melanoma cells and intense fluorescence emission inside the B16-F10 murine melanoma cells, making them suitable staining agents for imaging applications. 相似文献
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Successful massively multiplayer online games (MMOGs) have today millions of registered users and hundreds of thousands of active concurrent players. To be able to guarantee quality of service (QoS) to a highly variable number of concurrent users, game operators statically over-provision a large infrastructure capable of sustaining the game peak load, even though a large portion of the resources is unused most of the time. To address this problem, we introduce in this work a new MMOG ecosystem for hosting and provisioning of MMOGs which effectively splits the traditional monolithic MMOG companies into three main service providers: game providers, game operators, and resource providers. Their interaction is regulated through comprehensive service level agreements (SLA) that establish the price, terms of operation, and compensation for service violations. In our model, game operators efficiently provision resources for MMOGs from multiple cloud providers, based on dynamic load forecasts, and ensure proper game operation that maintains the required QoS to all clients under varying resource availability. Game providers manage multiple distributed MMOGs for which they lease services under strict operational SLAs from game operators to satisfy all client requests. These three self-standing, smaller, more agile service providers enable access to the MMOG market for the small and medium enterprises, and to the current commercial cloud providers. We evaluate, through simulations based on real-life MMOG traces and commercial cloud SLAs, the impact of resource availability on the QoS offered to the MMOG clients. We find that our model can mitigate the negative effects of resource failures within four minutes and that MMOG server consolidation can accentuate the negative effects of failures in a resource-scarce environment. We further investigate different methods of ranking MMOG operational offers with either single or multiple (competing) MMOG providers. Our results show that compensations for SLA faults in the offer selection process can lead up to 11–16 % gain in the game providers’ income. We also demonstrate that adequate ranking of offers can lead to MMOG operational cost reductions from 20 up to 60 %. 相似文献
7.
Adina L. Ghirişan Simion Drǎgan Alexandru Pop Marinela Simihǎian Vasile Miclǎuş 《加拿大化工杂志》2007,85(6):900-905
The influence of the apatite on the efficiency of neutralization and on heavy metal removal of acid mine waste water has been studied. The analysis of the treated waste water samples with apatite has shown an advanced purification, the concentration of the heavy metals after the treatment of the waste water with apatite being 25 to 1000 times less than the Maximum Concentration Limits admitted by European Norms (NTPA 001/2005). In order to establish the macro‐kinetic mechanism in the neutralization process, the activation energy, Ea, and the kinetic parameters, rate coefficient of reaction, kr, and kt were determined from the experimental results obtained in “ceramic ball‐mill” reactor. The obtained values of the activation energy Ea >> 42 kJ mol?1 (e.g. Ea = 115.50 ± 7.50 kJ mol?1 for a conversion of sulphuric acid ηH2SO4 = 0.05, Ea = 60.90 ± 9.50 kJ mol?1 for η H2SO4 = 0.10 and Ea = 55.75 ± 10.45 kJ mol‐1 for η H2SO4 = 0.15) suggest that up to a conversion of H2SO4 equal 0.15 the global process is controlled by the transformation process, adsorption followed by reaction, which means surface‐controlled reactions. At a conversion of sulphuric acid η H2SO4 > 0.15, the obtained values of activation energy Ea < 42 kJ mol‐1 (e.g. Ea = 37.55 ± 4.05 kJ mol‐1 for η H2SO4 = 0.2, Ea = 37.54 ± 2.54 kJ mol‐1 for η H2SO4 = 0.3 and Ea = 37.44 ± 2.90 kJ mol‐1 for η H2SO4 = 0.4) indicate diffusion‐controlled processes. This means a combined process model, which involves the transfer in the liquid phase followed by the chemical reaction at the surface of the solid. Kinetic parameters as rate coefficient of reaction, kr with values ranging from (5.02 ± 1.62) 10‐4 to (8.00 ± 1.55) 10‐4 (s‐1) and transfer coefficient, kt, ranging from (8.40 ± 0.50) 10‐5 to (10.42 ± 0.65) 10‐5 (m s‐1) were determined. 相似文献
8.
We present a novel approach for extreme simplification of point set models, in the context of real-time rendering. Point sets
are often rendered using simple point primitives, such as oriented discs. However, this requires using many primitives to
render even moderately simple shapes. Often, one wishes to render a simplified model using only a few primitives, thus trading
accuracy for simplicity. For this goal, we propose a more complex primitive, called a splat, that is able to approximate larger and more complex surface areas than oriented discs. We construct our primitive by decomposing
the model into quasi-flat regions, using an efficient algebraic multigrid algorithm. Next, we encode these regions into splats
implemented as planar support polygons textured with color and transparency information and render the splats using a special
blending algorithm. Our approach combines the advantages of mesh-less point-based techniques with traditional polygon-based
techniques. We demonstrate our method on various models. 相似文献
9.
Daniela PatrascuAuthor VitaeIulia DavidAuthor Vitae Vasile DavidAuthor VitaeConstantin MihailciucAuthor Vitae Ioan StamatinAuthor VitaeJean CiureaAuthor Vitae Livia NagyAuthor VitaeGéza NagyAuthor Vitae Anton Alexandru CiucuAuthor Vitae 《Sensors and actuators. B, Chemical》2011,156(2):731-736
Iron(II) phthalocyanine (FePc) modified multi-wall carbon nanotubes paste electrodes (MWCNTPEs) were used as voltammetric sensors to selectively detect dopamine (DA) in the presence of serotonin (5-HT). The electrochemical behavior of DA at the new modified electrode was investigated using CV. The enhanced current response of DA indicates that FePc modification of the MWCNTPE surface results in a high catalytic activity for the redox reaction of DA. Differential pulse voltammetry was applied in detection of DA and 5-HT at FePc-MWCNTPE. The method parameters were optimized. Detection limit of 2.05 × 10−7 M was obtained for DA by using the electrocatalytic oxidation signal corresponding to the FeII/FeIII redox process. The separation between the peak potentials of DA and 5-HT is 170 mV which is large enough for the simultaneously, selective determination of the two chemical species in their mixtures. There was no electrochemical response for ascorbic acid (AA) added in the sample. The monoamine neurotransmitter measuring method has been tested in analyzing deproteinized serum samples. 相似文献
10.
In this paper, the discrete-time exponential forgetting factor observer is specialised for the joint estimation of state and parameters, leading to an adaptive observer in which the decay rates of the estimation errors for the two distinct objects can be quasi-separated. The effectiveness of the observer is demonstrated through numerical simulation. 相似文献