Finite Element Time-Domain Body-of-Revolution Maxwell Solver based on Discrete Exterior Calculus

We present a finite-element time-domain (FETD) Maxwell solver for the analysis of body-of-revolution (BOR) geometries based on discrete exterior calculus (DEC) of differential forms and transformation optics (TO) concepts. We explore TO principles to map the original 3-D BOR problem to a 2-D one in the meridian plane based on a Cartesian coordinate system where the cylindrical metric is fully embedded into the constitutive properties of an effective inhomogeneous and anisotropic medium that fills the domain. The proposed solver uses a TE/TM field decomposition and an appropriate set of DEC-based basis functions on an irregular grid discretizing the meridian plane. A symplectic time discretization based on a leap-frog scheme is applied to obtain the full-discrete marching-on-time algorithm. We validate the algorithm by comparing the numerical results against analytical solutions for resonant fields in cylindrical cavities and against pseudo-analytical solutions for fields radiated by cylindrically symmetric antennas in layered media. We also illustrate the application of the algorithm for a particle-in-cell (PIC) simulation of beam-wave interactions inside a high-power backward-wave oscillator.Comment: 42 pages, 19 figure

Quantum Information Propagation Preserving Computational Electromagnetics

We propose a new methodology, called numerical canonical quantization, to solve quantum Maxwell's equations useful for mathematical modeling of quantum optics physics, and numerical experiments on arbitrary passive and lossless quantum-optical systems. It is based on: (1) the macroscopic (phenomenological) electromagnetic theory on quantum electrodynamics (QED), and (2) concepts borrowed from computational electromagnetics. It was shown that canonical quantization in inhomogeneous dielectric media required definite and proper normal modes. Here, instead of ad-hoc analytic normal modes, we numerically construct complete and time-reversible normal modes in the form of traveling waves to diagonalize the Hamiltonian. Specifically, we directly solve the Helmholtz wave equations for a general linear, reciprocal, isotropic, non-dispersive, and inhomogeneous dielectric media by using either finite-element or finite-difference methods. To convert a scattering problem with infinite number of modes into one with a finite number of modes, we impose Bloch-periodic boundary conditions. This will sparsely sample the normal modes with numerical Bloch-Floquet-like normal modes. Subsequent procedure of numerical canonical quantization is straightforward using linear algebra. We provide relevant numerical recipes in detail and show an important numerical example of indistinguishable two-photon interference in quantum beam splitters, exhibiting Hong-Ou-Mandel effect, which is purely a quantum effect. Also, the present methodology provides a way of numerically investigating existing or new macroscopic QED theories. It will eventually allow quantum-optical numerical experiments of high fidelity to replace many real experiments as in classical electromagnetics.Comment: 17 pages, 11 figures, journal article submitted to Physical review A (under review

Prevention Schemes Against Phishing Attacks on Internet Banking Systems

Abstract With the rise of Internet banking, phishing has become a major problem in online banking systems. Over time, highly evolved phishing attacks, such as active phishing, have emerged as a serious issue. Thus, we suggest two server authentication schemes based on SSL/TLS to protect Internet banking customers from phishing attacks. The first scheme uses the X.509 client certificate, which includes a personal identification message from the customer in order to recognize a genuine banking server. The second scheme, based on the first one, is a modified version of SSL/TLS. We also analyze our schemes using attack scenarios and an analysis table

Accelerating Particle-in-Cell Kinetic Plasma Simulations via Reduced-Order Modeling of Space-Charge Dynamics using Dynamic Mode Decomposition

We present a data-driven reduced-order modeling of the space-charge dynamics for electromagnetic particle-in-cell (EMPIC) plasma simulations based on dynamic mode decomposition (DMD). The dynamics of the charged particles in kinetic plasma simulations such as EMPIC is manifested through the plasma current density defined on the edges of the spatial mesh. We showcase the efficacy of DMD in modeling the time evolution of current density through a low-dimensional feature space. Not only do such DMD-based predictive reduced-order models help accelerate EMPIC simulations, they also have the potential to facilitate investigative analysis and control applications. We demonstrate the proposed DMD-EMPIC scheme for reduced-order modeling of current density, and speed-up in EMPIC simulations involving electron beams under the influence of magnetic fields and virtual cathode oscillations

High colloidal stability ZnO nanoparticles independent on solvent polarity and their application in polymer solar cells

Significant aggregation between ZnO nanoparticles (ZnO NPs) dispersed in polar and nonpolar solvents hinders the formation of high quality thin film for the device application and impedes their excellent electron transporting ability. Herein a bifunctional coordination complex, titanium diisopropoxide bis(acetylacetonate) (Ti(acac)2) is employed as efficient stabilizer to improve colloidal stability of ZnO NPs. Acetylacetonate functionalized ZnO exhibited long-term stability and maintained its superior optical and electrical properties for months aging under ambient atmospheric condition. The functionalized ZnO NPs were then incorporated into polymer solar cells with conventional structure as n-type buffer layer. The devices exhibited nearly identical power conversion efficiency regardless of the use of fresh and old (2 months aged) NPs. Our approach provides a simple and efficient route to boost colloidal stability of ZnO NPs in both polar and nonpolar solvents, which could enable structure-independent intense studies for efficient organic and hybrid optoelectronic devices

Review of the Current Status of Intra-Arterial Thrombolysis for Treating Acute Cerebral Infarction: a Retrospective Analysis of the Data from Multiple Centers in Korea

Objective The purpose of the study was to review the current status of intra-arterial (IA) thrombolysis in Korea by conducting a retrospective analysis of the data from multiple domestic centers. Materials and Methods The radiologists at each participating institution were asked to fill out case report forms on all patients who had undergone IA recanalization due to acute anterior circulation ischemia. These forms included clinical, imaging and procedure-related information. A central reader analyzed the CT/MR and angiographic results. The rates of successful recanalization, hemorrhagic transformation and functional outcome were obtained. The univariate analyses were performed together with the multivariate analysis. Results We analyzed the data from 163 patients, and they had been treated at seven institutes. The initial imaging modalities were CT for 46 patients (28%), MR for 63 (39%), and both for 54 (33%). Various mechanical treatment methods were applied together in 50% of the patients. Radiologically significant hemorrhage was noted in 20/155 patients (13%). We found various factors that influenced the recanalization rate and the occurrence of significant hemorrhagic transformations. The favorable outcome rate, reported as modified Rankin Scale ≤ 2, was 40%, and the mortality rate was 11%. The factors that predicted a poor functional outcome were old age (p = 0.01), initially severe neurological symptoms (p < 0.0001), MR findings of a wide distribution of lesions (p = 0.001), involvement of the basal ganglia (p = 0.01), performance of procedures after working hours (p = 0.01), failure of recanalization (p = 0.003), contrast extravasation after the procedure (p = 0.007) and significant hemorrhagic transformation (p = 0.002). The subsequent multivariate analysis failed to show any statistically significant variable. Conclusion There was a trend toward increased dependency on MR imaging during the initial evaluation and increased usage of combined pharmacologic/mechanical thrombolysis. The imaging and clinical outcome results of this study were comparable to those of the previous major thrombolytic trials.ope

멀티피직스 및 멀티스케일 전자기 수치해석 모델링 전략

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Time-Domain Quantum Maxwell Solver

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