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SIMULTANEOUS RECONSTRUCTION OF OPTICAL AND ACOUSTICAL PROPERTIES IN PHOTOACOUSTIC IMAGING USING PLASMONICS
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| Pengarang | : | - |
| Nama Majalah/Jurnal | : | Siam Journal On Applied Mathematics |
| Volume / Edisi | : | 83 (No. 4) |
| Halaman | : | 1738-1765 |
| Abstrak | : | We propose an approach for the simultaneous reconstruction of the electromag netic and acoustic material parameters, in the given medium \Omega where we want to image, using the photoacoustic pressure, measured on a single point of the boundary of \Omega , generated by plasmonic nanoparticles injected inside \Omega . As measurements, we use the generated pressure, that we denote by p \star (x,z,s,\omega ), depending on only one fixed point x\in \partial \Omega , where we measure, the time variable s, in a large enough interval, and the incidence frequency \omega , in a large enough band. These measurements are repeated while the location z of the nanoparticle is moved inside \Omega to scan it. We show that these measurements (which are five-dimensional in terms of dimensionality) are enough to recon struct both the sound speed, the mass density, and the permittivity inside \Omega (i.e., 3 coefficients of three dimensions each in terms of dimensionality). Indeed, from the behavior of the measured pres sure in terms of time, we can estimate the travel time of the pressure, for arriving points inside \Omega , then using the eikonal equation we reconstruct the acoustic speed of propagation, inside \Omega . In addition, we reconstruct the internal values of the acoustic Green's function. From the singularity analysis of this Green's function, we extract the integrals along the geodesics, for internal arriving points, of the log arithmic gradient of the mass density. Solving this (internal) integral geometric problem provides us with the values of the mass density function inside \Omega . Finally, from the behavior of p \star (x,z,s,\omega ) with respect to the frequency \omega , we detect the generated plasmonic resonances from which we reconstruct the permittivity inside \Omega . (This article was changed because of a production error.) |
AN ALGORITHM FOR FINDING WEAKLY REVERSIBLE DEFICIENCY ZERO REALIZATIONS OF POLYNOMIAL DYNAMICAL SYSTEMS
| Pengarang | : | - |
| Nama Majalah/Jurnal | : | Siam Journal On Applied Mathematics |
| Volume / Edisi | : | 83 (No. 4) |
| Halaman | : | 1717-1737 |
| Abstrak | : | Systems of differential equations with polynomial right-hand sides are very common in applications. On the other hand, their mathematical analysis is very challenging in general, due to the possibility of complex dynamics: multiple basins of attraction, oscillations, and even chaotic dynamics. Even if we restrict our attention to mass-action systems, all of these complex dynamical behaviors are still possible. On the other hand, if a polynomial dynamical system has a weakly reversible deficiency zero (WR0) realization, then its dynamics is known to be remarkably simple: oscillations and chaotic dynamics are ruled out, and, up to linear conservation laws, there exists a single positive steady state, which is asymptotically stable. Here we describe an algorithm for finding WR0 realizations of polynomial dynamical systems, whenever such realizations exist. |
PENGUASA YANG TIDAK BAIK PERLU DILAWAN
| Pengarang | : | TANJA .I VICTOR |
| Nama Majalah/Jurnal | : | Bina Darma |
| Volume / Edisi | : | 15-55 (No. 55) |
| Halaman | : | 28-37 |
| Abstrak | : | - |
STRUCTURED SYSTEMS OF NONLINEAR EQUATIONS
| Pengarang | : | - |
| Nama Majalah/Jurnal | : | Siam Journal On Applied Mathematics |
| Volume / Edisi | : | 83 (No. 4) |
| Halaman | : | 1696-1716 |
| Abstrak | : | In a ``structured system"" of equations, each equation depends on a specified subset of the variables. In this article, we explore properties common to ``almost every"" system with a f ixed structure and how the properties can be read from the corresponding connection graph. A solution p of a system F(p)=c is called robust if it persists despite small changes in F. We establish methods for determining robustness that depends on the structure, as expressed in the properties of the corresponding directed graph of the structured system. The keys to understanding linear and nonlinear structured systems are subsets of variables that we call forward and backward bottlenecks. In particular, when robustness fails in a structured system, it is due to the existence of a unique ` `backward bottleneck"" that we call a ``minimax bottleneck."" We present a numerical method for locating the minimax bottleneck. We show how to remove it by adding edges to the graph. |
PERAN ANGKATAN BERSENJATA DALAM MENJAGA EKSISTENSI NEGARA
| Pengarang | : | - |
| Nama Majalah/Jurnal | : | Bina Darma |
| Volume / Edisi | : | 15-55 (No. 55) |
| Halaman | : | 20-27 |
| Abstrak | : | - |
TRANSPORT MODELS FOR WAVE PROPAGATION IN SCATTERING MEDIA WITH NONLINEAR ABSORPTION
| Pengarang | : | - |
| Nama Majalah/Jurnal | : | Siam Journal On Applied Mathematics |
| Volume / Edisi | : | 83 (No. 4) |
| Halaman | : | 1677-1695 |
| Abstrak | : | This work considers the propagation of high-frequency waves in highly scattering media where physical absorption of a nonlinear nature occurs. Using the classical tools of the Wigner transform and multiscale analysis, we derive semilinear radiative transport models for the phase-space intensity and the diffusive limits of such transport models. As an application, we consider an inverse problem for the semilinear transport equation, where we reconstruct the absorption coefficients of the equation from a functional of its solution. We obtain a uniqueness result on the inverse problem. |
NASIONALISME DAN INTEGRASI NASIONAL DARI UNITARISME VS FEDERALISME KE NASIONALISME VS NASIONALISME BARU
| Pengarang | : | Flip Litaay |
| Nama Majalah/Jurnal | : | Bina Darma |
| Volume / Edisi | : | 15-55 (No. 55) |
| Halaman | : | 10-19 |
| Abstrak | : | - |
FLOW MEASUREMENT: ANINVERSE PROBLEM FORMULATION
| Pengarang | : | - |
| Nama Majalah/Jurnal | : | Siam Journal On Applied Mathematics |
| Volume / Edisi | : | 83 (No. 4) |
| Halaman | : | 1654-1676 |
| Abstrak | : | This paper proposes a new mathematical formulation for flow measurement based on the inverse source problem for wave equations with partial boundary measurement. Inspired by the design of acoustic Doppler current profilers (ADCPs), we formulate an inverse source problem that can recover the flow field from the observation data on boundary receivers. To our knowledge, this is the first mathematical model of flow measurement using partial differential equations. This model is proved well-posed, and the corresponding algorithm is derived to compute the velocity field efficiently. Extensive numerical simulations are performed to demonstrate the accuracy and robustness of our model. The comparison results demonstrate that our model is ten times more accurate than ADCP. Our formulation is capable of simulating a variety of practical measurement scenarios. |
HAKEKAT NEGARA
| Pengarang | : | - |
| Nama Majalah/Jurnal | : | Bina Darma |
| Volume / Edisi | : | 15-55 (No. 55) |
| Halaman | : | 5-9 |
| Abstrak | : | - |
UNIFIED APPROACH TO FLOQUET LATTICES, TOPOLOGICAL INSULATORS, AND THEIR NONLINEAR DYNAMICS
| Pengarang | : | - |
| Nama Majalah/Jurnal | : | Siam Journal On Applied Mathematics |
| Volume / Edisi | : | 83 (No. 4) |
| Halaman | : | 1623-1653 |
| Abstrak | : | A unified method for analyzing the dynamics and topological structure associated with a class of Floquet topological insulators is presented. The method is applied to a system that describes the propagation of electromagnetic waves through the bulk of a two-dimensional lattice that is helically driven in the direction of propagation. Tight-binding approximations are employed to derive reduced dynamical systems. Further asymptotic approximations, valid in the high-frequency driving regime, yield a time-averaged system which governs the leading order behavior of the wave. From this follows an analytic calculation of the Berry connection, curvature, and Chern number via analyzing the local behavior of the eigenfunctions near the critical points of the spectrum. Examples include honeycomb, Lieb, kagome, and 1/5-depleted lattices. In the nonlinear regime, novel equations governing slowly varying wave envelopes are derived. For the honeycomb lattice, numerical simulations show that for relatively small nonlinear effects a striking spiral pattern occurs; as nonlinearity increases, localized structures emerge, and for somewhat higher nonlinearity the waves appear to collapse |