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- 摘要
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- 实验方案
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Topological defect enabled formation of nematic domains
摘要： We study numerically curvature and electric field driven domain formation and reorientations in two-dimensional nematic liquid crystals within square confinement. We use the Landau-de Gennes description in terms of the nematic tensor order parameter. We show that on increasing the amplitude of a sinusoidally shaped confining wall, pairs {defect, antidefect} are formed, which enable insertion of domains displaying significantly different average orientational order with respect to the surrounding nematic body. Furthermore, we study E-driven transformation between two competing degenerate domain-type structures. We show that transformations could be mediated via qualitatively different intermediate structures possessing topological defects.
关键词： Nematic liquid crystals,topological defects,order reconstruction,phenomenological modelling
更新于2025-09-11 14:15:04
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Colour removal of phthalocyanine based reactive dye by nanoparticles
摘要： Synthesized iron-nickel (Fe–Ni) bimetallic nanoparticles (NPs) were utilized for the colour removal of C. I. Reactive Blue 21 (RB21) dye. NPs agglomeration was prevented using polyvinyl pyrrolidone (PVP) as capping agent. The NPs were characterized by nanoparticle size analysis, TEM, XRD and EDX. The operational conditions like pH, NPs concentration and initial dye concentration for decolourization were optimized using mathematical modelling and its kinetics were studied. Influence of the presence of alkali and salt on dye decolourization was also investigated. Decolourization products were analysed by using FTIR and GCMS analysis. 93.46% of dye decolourization was obtained and reduction in COD, BOD values was achieved along with minimal sludge generation.
关键词： bimetallic,phthalocyanine,kinetics,mathematical modelling,Reactive Blue 21
更新于2025-09-11 14:15:04
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A simulation tool for better management of retinal services
摘要： Background: Advances in the management of retinal diseases have been fast-paced as new treatments become available, resulting in increasing numbers of patients receiving treatment in hospital retinal services. These patients require frequent and long-term follow-up and repeated treatments, resulting in increased pressure on clinical workloads. Due to limited clinic capacity, many National Health Service (NHS) clinics are failing to maintain recommended follow-up intervals for patients receiving care. As such, clear and robust, long term retinal service models are required to assess and respond to the needs of local populations, both currently and in the future. Methods: A discrete event simulation (DES) tool was developed to facilitate the improvement of retinal services by identifying efficiencies and cost savings within the pathway of care. For a mid-size hospital in England serving a population of over 500,000, we used 36 months of patient level data in conjunction with statistical forecasting and simulation to predict the impact of making changes within the service. Results: A simulation of increased demand and a potential solution of the ‘Treat and Extend’ (T&E) regimen which is reported to result in better outcomes, in combination with virtual clinics which improve quality, effectiveness and productivity and thus increase capacity is presented. Without the virtual clinic, where T&E is implemented along with the current service, we notice a sharp increase in the number of follow-ups, number of Anti-VEGF injections, and utilisation of resources. In the case of combining T&E with virtual clinics, there is a negligible (almost 0%) impact on utilisation of resources. Conclusions: Expansion of services to accommodate increasing number of patients seen and treated in retinal services is feasible with service re-organisation. It is inevitable that some form of initial investment is required to implement service expansion through T&E and virtual clinics. However, modelling with DES indicates that such investment is outweighed by cost reductions in the long term as more patients receive optimal treatment and retain vision with better outcomes. The model also shows that the service will experience an average of 10% increase in surplus capacity.
关键词： Virtual clinics,Retinal services,Discrete event simulation,Treat and extend,Patient flow modelling
更新于2025-09-11 14:15:04
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Two-dimensional projection Monte Carlo estimators for the study of angular characteristics of polarized radiation
摘要： The paper presents a Monte Carlo algorithm for the study of bidirectional angular characteristics of a scattered polarized radiation based on projection expansion of the density of the corresponding angular distribution over hemispherical harmonics. The results of numerical estimation of two-dimensional angular distributions of the intensity and the polarization degree of the radiation passed through and reflected from optically thick layers of scattering and absorbing substance are presented.
关键词： statistical modelling,radiation transfer,Monte Carlo methods,orthogonal expansion,hemispherical harmonics
更新于2025-09-11 14:15:04
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[IEEE IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Valencia, Spain (2018.7.22-2018.7.27)] IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Monitoring Evapotranspiration with Remote Sensing Data and Ground Data Using Ensemble Model Averaging
摘要： Evapotranspiration (ET) can be mapped using thermal infrared and spectral reflectance data. Various ET models have been developed but there was no competitive evaluation of them over a large range of situations. Ensemble model averaging is a tool that can be used for deriving ET from multi-model simulations. In this study, we used bayesian model averaging, which consists in weighting each model according to their performances when deriving the ensemble average. It was applied to the monitoring of ET over a saltmarsh scrub area in South France from MODIS data. ET monitoring was improved (RMSE = 0.57 mm d-1) when using a weighted averaging procedure as compared to the performances of a simple average or to the performances of each individual model.
关键词： thermal infrared,energy balance,ensemble modelling,contextual models,evapotranspiration
更新于2025-09-10 09:29:36
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Mesoporous titania-coated biosensor and FEM model design for highly sensitive detection of low molecular weight targets
摘要： This paper presents the interest of a highly sensitive biosensor coated with a TiO2 mesoporous film as sensitive layer. The main novelty is related to the modelling of the device and simulation by using Finite Element Method with COMSOL Multiphysics software, as a good way to take into account the physical properties of porous 3D-layers. The strategy of using such Love wave devices, with 3D porous layers, offering further easy functionalization, aims not only to increase the amount of targets caught on the sensor surface, but also to enhance the detection mechanism by a higher perturbation of the Love wave acoustic energy which could be trapped inside the 3D sensitive layer. First, as a proof of concept, experimental devices with a 3D titania mesoporous layer were realized, and they have shown a good agreement with simulated results. Furthermore, experimental test with several Newtonian liquids are investigated, in a range of viscosities from 1 to 7 cP, typical of those concerned by our biochemical applications. The sensitivity with a 300 nm thick porous sensing layer was 10 times that of the bare device, with interesting dynamical issues to be further studied, giving rise to the great potentialities of such architectures for biological detection of low weight biochemical targets.
关键词： surface to volume ratio,mesoporous materials,biochemical sensing,Radio Frequency Love wave device,finite element modelling,acoustic interaction in liquid medium
更新于2025-09-10 09:29:36
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[Handbook of Numerical Analysis] Processing, Analyzing and Learning of Images, Shapes, and Forms: Part 1 Volume 19 || Factoring Scene Layout From Monocular Images in Presence of Occlusion
摘要： Discovering 3D arrangements of objects from single indoor monocular images is important given its many applications such as scene understanding, interior design, and content creation for AR and VR applications. The extracted information (e.g., arrangement of typical objects expressed as distributions) can provide valuable cues as to how our surrounding indoor environments are organized and how we interact with such objects. Although heavily researched in the recent years, existing approaches quickly break down under medium to heavy occlusion as the core image-space region detection module (e.g., RCNN or its variants) fails in absence of directly visible cues. Instead, we explore using holistic contextual 3D information and exploit the fact that objects in indoor scenes cooccur mostly in typical configurations. First, we use a neural network trained on real indoor annotated images to extract 2D image-space keypoints and feed them to a 3D candidate object generation stage. Then, we solve a global selection problem among these candidates using pairwise cooccurrence statistics discovered from a large 3D scene database. We iterate the process allowing for candidates with low keypoint response to be incrementally detected based on the location of the already discovered nearby objects. We demonstrate how combining deep features with shape optimization leads to performance improvement over combinations of state-of-the-art methods, especially for scenes with moderate/severe occlusion.
关键词： Keypoint detection,Data-driven modelling,Occlusion handling,Layout estimation
更新于2025-09-10 09:29:36
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[IEEE 2018 12th International Congress on Artificial Materials for Novel Wave Phenomena (Metamaterials) - Espoo, Finland (2018.8.27-2018.9.1)] 2018 12th International Congress on Artificial Materials for Novel Wave Phenomena (Metamaterials) - Optimization of Meta-atoms for 3D Printed Metamaterial Structures
摘要： Additive manufacturing by fused deposition modelling (FDM) now offers some useful performance for functional materials including conductors. Whilst this technology enables the creation of truly three-dimensional (3D) composite structures its accuracy and resolution are not yet so refined as those of 2D fabrication methods. Moreover, dielectric and metallic filaments used in FDM have complex material properties that depend on print parameters and usually exhibit higher losses than RF substrates and bulk conductors. In this work we investigate by simulations and experiments several magnetic meta-atom variants with a view to developing optimal designs for the successful production of metamaterials at microwaves with FDM techniques. Conductor thickness is shown to be a useful new design parameter to reach the desired degree of miniaturization and resonance quality factor of the meta-atoms at low print resolution.
关键词： 3D printing,Fused deposition modelling,Additive manufacturing,Meta-atoms,Metamaterials
更新于2025-09-10 09:29:36
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AIP Conference Proceedings [Author(s) SolarPACES 2017: International Conference on Concentrating Solar Power and Chemical Energy Systems - Santiago, Chile (26–29 September 2017)] - Numerical study of a two pass shell and tube latent heat energy storage system
摘要： The thermal behaviour of PCM in different configuration of heat exchangers is analysed for the purpose of design and optimisation of a latent heat thermal energy storage unit. Numerical modelling in conjunction with scale analyses provides a cost effective means to examine the performance of different configurations of latent heat storage systems. The main objective of this work is to scale down an experimental set up to a numerical model which can represent the thermal behaviour of the system with reasonable computational time. A U-tube element from a shell and tube thermal storage experimental set up was used as the model for a numerical study, using FLUENT. The predicted results of the temperature profiles in the PCM domain are in agreement with the measured data. Moreover, the heat transfer fluid outlet temperature and duration of the phase change processes are consistent with experimental results. Using the experimental initial temperature at each point in comparison to using an average initial temperature from all points can improve the predicted temperature profiles. Furthermore, three different mushy zone constants; namely 105, 107, 108 were used to examine the impact on the rate of melting. It was found that the constant 107 provides a closer solution to the experimental results. Results of this study show that the small scale model can represent the lab scale set up, providing more detail about the thermal behaviour of the PCM which is difficult to capture by measurement. The model can also be used for further examination of a high temperature PCM within the same set up for a CSP application.
关键词： FLUENT,shell and tube,numerical modelling,PCM,latent heat thermal energy storage
更新于2025-09-10 09:29:36
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[IEEE 2018 11th International Symposium on Communication Systems, Networks and Digital Signal Processing (CSNDSP) - Budapest (2018.7.18-2018.7.20)] 2018 11th International Symposium on Communication Systems, Networks & Digital Signal Processing (CSNDSP) - Infrared Mobile Transmissions for Smart Indoor Applications
摘要： Optical wireless communication systems has many applications in smart environments, such as visible light-based ones because providing both illumination and downlinks. However, the uplink design remains difficult especially considering mobile transmitters. In this paper, we study an infrared uplink using an optical transmitter in a mobile sensor device that is placed either on a robotic platform, or worn by a person. The infrared channel modelling takes into account line-of-sight and non-line-of-sight links along with blockages linked to human or robot presence. We show the importance of taking into account human body in channel modelling for the evaluation of the results according to the different cases. In addition, we highlight a compromise in the choice of the characteristics of the optical elements between obtaining the best performance and underestimating performance evaluation when taking or not into account the body in the channel modelling. Experiments permits validating theoretical conclusions.
关键词： Line-of Sight,non-Line-of Sight,channel modelling,infrared transmissions,LiFi for medical applications
更新于2025-09-10 09:29:36