Dual Variable System Research Articles

Dual-Retarder Mueller Polarimetry System for Extraction of Optical Properties of Serum Albumin Protein Media.

A dual liquid-crystal variable retarder Mueller polarimetry system incorporating a gold-based surface plasmon resonance prism coupler was proposed for extracting the optical properties of serum albumin protein media in the reflectance configuration. The feasibility of the proposed system was demonstrated by measuring the circular dichroism and circular birefringence properties of glucose tissue phantom solutions with different albumin concentrations. The results showed that the circular dichroism increased with albumin concentration, while the optical rotation angle increased with glucose concentration. Both properties reduced over time as a result of the protein glycation effect, which led to a gradual reduction in the glucose content of the sample.

Research on Power Matching and Energy Optimal Control of Active Load-Sensitive Electro-Hydrostatic Actuator

Electro-hydrostatic actuator (EHA) is an important type of power-by-wire (PBW) which is a highly integrated closed volume control system with the advantages of high reliability, high efficiency and easy maintenance. However, under heavy load conditions, a large amount of heat the EHA motor produces affects the system’s working time and even the system life, which restricts the widespread application of EHA systems. In order to solve the problem of motor heating and the contradiction between high dynamics and high efficiency of the EHA system, a novel active load-sensitive principle and structure of EHA system is proposed based on the load-sensitive principle. The active load-sensitive EHA (ALS-EHA) is a dual control variable system consisting of a motor pump main loop and a load-sensitive loop. As for the latter, the system load pressure is introduced into a special designed and optimized pressure fellow valve (PFV). The valve outlet is connected to the plunger pump swash plate variable mechanism. The EHA pump displacement is actively adjusted by controlling the current input to PFV. The two-degree-of-freedom cooperative control for the output flow of the pump can be implemented by adjusting the motor speed and the pump displacement. An energy optimal robust control law based on fuzzy and disturbance compensation is presented for the control architecture. The simulation results show that the ALS-EHA system based on the control law proposed in this paper can effectively reduce the motor heat while ensuring the dynamic performance of the system.

Optimization of a SPECT system for imaging of 90Y in liver using Monte Carlo method

Introduction: Acquiring a high quality image has assigned an important concern for obtaining accurate diagnosis in nuclear medicine. Detector and collimator are critical component of Single Photon Emission Computed Tomography (SPECT) imaging system for giving accurate information from exact pattern of radionuclide distribution in the target organ. The images are strongly affected by the attenuation, scattering, and response of the detector and collimator. Method and material: The Planar and SPECT scans of a Y90 point source and also an extended Cardiac- Torso(XCAT) computerized phantom with the experiment and simulated systems were prepared. The SIMIND Monte Carlo program was used for simulating Siemen’s dual head variable angle SPECT imaging system with 4 detectors and 10 collimators. After verification and validation of the simulated system, the similar scans of the phantoms were compared from the point of view of image quality for 4 scintillator crystals including: NaI(Tl), BGO, LuAG: Ce, LaBr3 and also 10 collimators: Pb, Pb-Sb, Pb-Sb3, Pb-bi-Sn19, Pb-bi Sn375, Pb-bi-Sn50, Pb-bi-Sn-cd10, Pb-bi-Sn-cd125, Pt and Pt-Co. The parameters of energy and spatial resolution, and sensitivity of the systems were compared. Images were analyzed qualitatively by two nuclear medicine specialists. RESULTS: FWHM of the mentioned crystals and collimators obtained where: NaI (Pb, 0.3853) and BGO (Pb-Sb, 0.406), (Pb-Bi-Sn375, 0.405), (Pb-Bi-Sn-cd125, 0.375), and LuAG: Ce crystal (Pb-Sb, 0.425), (Pb- Bi-Sn19, 0.407), (Pb-Bi-Sn375, 0.417) and also LaBr3 (Pb-Bi-Sn375, 0.407), (Pb-Bi-Sn50, 0.430), (Pt-Co, 0.355). Medical diagnosis of the SPECT images of the phantom showed that the system with NaI(Tl)and LaBr3 by Pb-Sn3 collimator potentially provides a better detectability for hot lesions in the liver of XCAT phantom. CONCLUSIONS: The results showed that crystal NaI(Tl)and LaBr3 by Pb-Sn3 collimator has a high sensitivity and resolution, and also provides a better lesion detectability from the point of view of image quality on XCAT phantom.

Dual Variables System Analysis for Timoshenko Beam

Regarding the displacements and internal forces of Timoshenko beams as dual variables, Timoshenko beam problems were included into dual variables system. Corresponding to state transfer solution of Hamiltonian dual equation, transfer form solution of dual variables for Timoshenko beams was presented. Based on transfer form solution, element stiffness equation and the shape functions of Timoshenko beams were deduced, boundary integral equation and the fundamental solution function of Timoshenko beams were obtained, which reveal the intrinsic relationships among the finite element method, the boundary element method and dual variables system of Timoshenko beams. Based on the transfer form solution of Timoshenko beams, transfer matrix method for chain structure of Timoshenko beams was proposed. For chain beam structure problems, transfer matrix method is simple, intuitive, and has the advantages of good boundary adaptability and less calculation in solving the node variables of chain structures with recursive solution. The numerical results demonstrate the feasibility and accuracy of transfer matrix method in complex beam structure problems.

Hybrid complete Mueller polarimeter based on phase modulators

Optical properties of matter as diattenuation, retardance and depolarization can be evaluated using polarimetric techniques. In this paper, the analysis and implementation of a complete Mueller polarimeter is presented. The system is constituted of a polarization state generator (PSG) and a polarization state analyzer (PSA), which are controlled and synchronized through a computer program. The PSG comprises a dual liquid crystal variable retarder system while the PSA is based on a two-photoelastic modulator setup. Using air and common polarizing optics as test samples for calibration at 633 nm, the hybrid instrument met a good precision when the Mueller matrices of those optical elements were measured.

EL-4 column and control

This article describes the electron optical column and some of its electronic controls for the new generation of electron-beam lithography system at IBM, designated EL-4. This new column utilizes variable shaped-beam technology and incorporates dual shaping optics for both triangular and rectangular shapes and triple deflection. The EL-4 system was designed for high-throughput 1/4 μm lithography with an edge resolution of 50 nm (extendable to 1/10 μm groundrules) over a 10 mm×10 mm field. The beam deflection optics uses a dual variable axis immersion lens system to achieve two stages of magnetic deflection and one stage of electric deflection. By design, all three stages of deflection are telecentric to eliminate overlay errors resulting from target plane height variations. A pixel throughput increase from our existing state-of-the-art system, the EL-3, of over an order of magnitude was required for this new system to write the next generation circuit patterns within reasonable times. A unique mechanical design approach for the column, utilizing a double-walled construction, combines the required mechanical rigidity and vacuum environment with exceptional electromagnetic interference shielding.

On a network method for unsteady incompressible fluid flow on triangular grids

AbstractThe dual variable method for Delaunay triangulations is a network‐theoretic method that transforms a set of primitive variable finite difference or finite element equations for incompressible flow into an equivalent system which is one‐fifth the size of the original. Additionally, it eliminates the pressures from the system and produces velocities that are exactly discretely divergence‐free. In this paper new discretizations of the convection term are presented for Delaunay triangulations, the dual variable method is extended to tessellations that contain obstacles, and an efficient algorithm for the solution of the dual variable system is described.

Iterative solution of Navier-Stokes dual variable difference equations

The dual transformation applied to implicit finite difference approximations of the Navier-Stokes equations reduces the number of unknowns by a factor of three, removes the pressures from the discrete equations and produces velocities which satisfy the discrete continuity equation exactly. New iterative methods for the solution of the unsymmetrical dual variable system are developed and are proven to converge for a large class of problems. These iterative methods involve a sequence of discrete Laplacian systems whose solutions converge to the solution of the dual variable system. They take advantage of the special structure of the dual variable coefficient matrix, are very fast compared to the direct methods currently used, are less memory intensive and can be more easily vectorized and parallelized.