Dimensional Targets Research Articles

HDD Reader Technology Roadmap to an Areal Density of 4 Tbpsi and Beyond

Massive data growth is accelerating the need for storage. Hard disk drive read/write technology continues to advance to support this demand. This Advanced Storage Research Consortium report combines a top-down (system) and bottom-up (micromagnetic) approach to define a reader technology roadmap for 2.4, 4.0, and 6.0 terabits per square inch (Tbpsi) including dimensional and performance targets. We examine the resolution, SNR, stability and manufacturing requirements, challenges, and gaps. We show that the extension of today’s spin valve-based reader designs may enable 4 Tbpsi, but significant gaps must be closed. For higher areal densities, we review future reader designs, challenges, and discuss potential solution paths.

High-dimensional MCMC with a standard splitting scheme for the underdamped Langevin diffusion.

The efficiency of a Markov sampler based on the underdamped Langevin diffusion is studied for high dimensional targets with convex and smooth potentials. We consider a classical second-order integrator which requires only one gradient computation per iteration. Contrary to previous works on similar samplers, a dimension-free contraction of Wasserstein distances and convergence rate for the total variance distance are proven for the discrete time chain itself. Non-asymptotic Wasserstein and total variation efficiency bounds and concentration inequalities are obtained for both the Metropolis adjusted and unadjusted chains. In particular, for the unadjusted chain, in terms of the dimension d and the desired accuracy ε, the Wasserstein efficiency bounds are of order d∕ε in the general case, d∕ε if the Hessian of the potential is Lipschitz, and d1∕4∕ε in the case of a separable target, in accordance with known results for other kinetic Langevin or HMC schemes.

Simulation of Quantum Radar Cross Section for Electrically Large Targets With GPU

As an extension of traditional radar, quantum radar has the advantages of enhancing detection capability and improving resolution, which has attracted enormous attentions. However, the researches on the scattering characteristics of quantum radar are limited to two-dimensional targets, impeding the practical applications of quantum radar. In this paper, the universal expression of quantum radar cross section (QRCS) for three-dimensional targets is introduced. We have demonstrated the achievement of large-scale computing of QRCS by using GPU accelerating technique. And QRCSs of typical two- and three- dimensional targets are compared with previous work to verify the accuracy, and the improved efficiency of acceleration method is indicated simultaneously. Ultimately, the QRCS of a typical electrically large and complex target, B2 aircraft, is simulated unprecedentedly. The proposed method is convinced to be an efficient tool for analyzing quantum radar scattering properties of electrically large structures.

Multisensor Data Fusion for Additive Manufacturing Process Control

Achieving cutting-edge mechanical properties of metal parts realized by additive manufacturing (AM) demands articulated process control strategies, due to the multitude of physical phenomena involved in this kind of manufacturing processes. Complexity is even higher for what concerns the direct energy deposition (DED) technique, which offers much more potential flexibility and efficiency with respect to other metal AM technologies, at the cost of more difficult process control. The present work presents a multisensor approach able to combine online signals, collected while monitoring the deposition process, and data coming from offline inspection devices, during the built part quality check phase. This data fusion approach constitutes the foundation for the process modeling phase and, consequently, for the implementation of an intelligent control strategy that would act online by adjusting the machine process parameters chasing part dimensional, mechanical, and quality targets. The benefits of the proposed solution are assessed through a dedicated experimental campaign on a DED machine.

An Efficient High-Frequency Method to Compute EM Scattering of a Target on Rough Surface

Abstract The physical optics and shooting and bouncing rays method are combined to rapidly compute the electromagnetic (EM) scattering from electrically large three- dimensional targets on a dielectric rough surface. To avoid modeling the rough surface of infinite extent, image theory is first used to account for the EM interactions between the target and the infinite planar surface. Next, the dielectric rough surface is accounted for by multiplying the Fresnel reflection coefficient with a roughness coefficient. In this way, only the target needs to be modeled. Thus, the proposed method can reduce significantly the computational costs and achieve a reasonable accuracy for the composite scattering problem, such as a ship-sea model.

Forming maps of targets having multiple reflectors with a biomimetic audible sonar.

A biomimetic audible sonar mimics human echolocation by emitting clicks and sensing echoes binaurally to investigate the limitations in acoustic mapping of 2.5 dimensional targets. A monaural sonar that provides only echo time-of-flight values produces biased maps that lie outside the target surfaces. Reflector bearing estimates derived from the first echoes detected by a binaural sonar are employed to form unbiased maps. Multiple echoes from a target introduce phantom-reflector artifacts into its map because later echoes are produced by reflectors at bearings different from those determined from the first echoes. In addition, overlapping echoes interfere to produce bearing errors. Addressing the causes of these bearing errors motivates a processing approach that employs template matching to extract valid echoes. Interfering echoes can mimic a valid echo and also form PR artifacts. These artifacts are eliminated by recognizing the bearing fluctuations that characterize echo interference. Removing PR artifacts produces a map that resembles the physical target shape to within the resolution capabilities of the sonar. The remaining differences between the target shape and the final map are void artifacts caused by invalid or missing echoes.

A Technique to Irradiate Scar-like Line Target With Dynamic Electron Arc Radiation Therapy

For superficial target such as surgical scar, standard radiotherapy technique is the static electron beam. Its use can become cumbersome when target area is long and/or the skin has large curvature, because the combination of multiple beams often produces hot and cold spots in the junction regions and surrounding healthy tissues can be over-irradiated. In addition, manual setup of each field is required which is often impractical clinically. In this study, we investigate a new technique to irradiate any line target with the dynamic electron arc radiotherapy (DEAR) where both the couch position and Linac gantry angle are synchronized with the radiation beam. The electron applicator is kept in DEAR to preserve beam penumbra. To avoid collision between Linac and patient, couch is moved simultaneously with gantry rotation to maintain a constant source to skin distance (SSD) and an en face beam direction at all times. The DEAR plan, in the form of XML, follows the MU-position trajectory model using control point (CP) similar to IMRT and VMAT, is currently deliverable on Truebeam Linac in research mode. The line target is represented by a series of connected points whose 3D coordinates are first extracted from treatment planning system. They are used to determine the gantry angle, couch position, collimator angle, and MU at each CP. The XML plan also includes some fixed parameters: energy, applicator, cutout, and dose rate. The plan and CT are fed to the Virtual Linac Monte Carlo simulation platform for the final dose calculation and prescription normalization. Finally the plan is verified dosimetrically on phantom with radiochromic film. Various target orientations and lengths were studied on flat, cylindrical, and anthropomorphic phantoms. Either 6 or 9 MeV electron beams were chosen depending on the depth of the target. The smallest applicator (6 × 6 cm2) is used for increased clearance. Cutout shape is in square (3 × 3 cm2), rectangular (3 × 1 cm2), or circular (dia = 3 cm). Dose rate is based on the prescription dose, speed of couch motion and gantry rotation, and delivery time. Plans are generated in both forward and reverse motion directions. Any number of setup beams during the motion trajectory can be created and mode up during the dry run. Gantry angle is chosen so that beam is always perpendicular to the target. For circular cutout, the collimator angle is fixed; for others, it is parallel to the scanning direction. Finally, the MU at each CP is proportional to the distance between the current and the neighboring target points. For a 20 cm long target with 200 cGy prescription dose, the delivery can be completed within 2 minutes at dose rate of 1000 MU/min. The film measurements agree well with the Monte Carlo dose calculations. We have developed a technique to irradiate any line target using DEAR. It improves dose distributions substantially over the standard electron beam. Further investigations are in progress to expand into two dimensional targets.

Design and experimental testing of an electro-thermal microgripper for cell manipulation

This paper presents the design, fabrication and experimental characterization of an electro-thermally actuated microgripper suitable for single-cell manipulation. The analysis of the mechanical properties of cells is of great interest both in medicine and biology because the study of the cellular mechanical behaviour and resistance is necessary in these fields. Microgrippers (Bio-MEMS) have an important role in the manipulation of biological tissues and cells. In recent works, the research group simulated the mechanical behavior of grippers and the different actuation strategies. Considering the dimensional specifications and targets imposed by actuation and biocompatibility, in this paper, a microgripper based on electro-thermal actuation is studied. Starting from previous numerical results, a novel SU8 structure is designed and realized according to the micro-fabrication constraints and then the structure is simulated using the finite element method (FEM)-based thermo-structural simulations in ANSYS. Therefore, the fabrication method and steps are presented and the gripper has been developed and tested. Finally, the tip displacements of the gripper, electro-thermally actuated in different operating conditions, are compared with those obtained by means of numerical FEM simulations. A good agreement is obtained between simulations and experimental results.

SINGLE IMAGE CAMERA CALIBRATION IN CLOSE RANGE PHOTOGRAMMETRY FOR SOLDER JOINT ANALYSIS

Abstract. Printed Circuit Boards (PCB) play an important role in the manufacturing of electronic devices. To ensure a correct function of the PCBs a certain amount of solder paste is needed during the placement of components. The aim of the current research is to develop an real-time, closed-loop solution for the analysis of the printing process where solder is printed onto PCBs. Close range photogrammetry allows for determination of the solder volume and a subsequent correction if necessary. Photogrammetry is an image based method for three dimensional reconstruction from two dimensional image data of an object. A precise camera calibration is indispensable for an accurate reconstruction. In our certain application it is not possible to use calibration methods with two dimensional calibration targets. Therefore a special calibration target was developed and manufactured, which allows for single image camera calibration.

SINGLE IMAGE CAMERA CALIBRATION IN CLOSE RANGE PHOTOGRAMMETRY FOR SOLDER JOINT ANALYSIS

Printed Circuit Boards (PCB) play an important role in the manufacturing of electronic devices. To ensure a correct function of the PCBs a certain amount of solder paste is needed during the placement of components. The aim of the current research is to develop an real-time, closed-loop solution for the analysis of the printing process where solder is printed onto PCBs. Close range photogrammetry allows for determination of the solder volume and a subsequent correction if necessary. Photogrammetry is an image based method for three dimensional reconstruction from two dimensional image data of an object. A precise camera calibration is indispensable for an accurate reconstruction. In our certain application it is not possible to use calibration methods with two dimensional calibration targets. Therefore a special calibration target was developed and manufactured, which allows for single image camera calibration.

SU‐E‐T‐754: Three‐Dimensional Patient Modeling Using Photogrammetry for Collision Avoidance

Purpose:To evaluate photogrammetry for creating a three‐dimensional patient model.Methods:A mannequin was configured on the couch of a CT scanner to simulate a patient setup using an indexed positioning device. A CT fiducial was placed on the indexed CT table‐overlay at the reference index position. Two dimensional photogrammetry targets were placed on the table in known positions. A digital SLR camera was used to obtain 27 images from different positions around the CT table. The images were imported into a commercial photogrammetry package and a 3D model constructed. Each photogrammetry target was identified on 2 to 5 images. The CT DICOM metadata and the position of the CT fiducial were used to calculate the coordinates of the photogrammetry targets in the CT image frame of reference. The coordinates were transferred to the photogrammetry software to orient the 3D model. The mannequin setup was transferred to the treatment couch of a linear accelerator and positioned at isocenter using in‐room lasers. The treatment couch coordinates were noted and compared with prediction. The collision free regions were measured over the full range of gantry and table motion and were compared with predictions obtained using a general purpose polygon interference algorithm.Results:The reconstructed 3D model consisted of 180000 triangles. The difference between the predicted and measured couch positions were 5 mm, 1 mm, and 1 mm for longitudinal, lateral, and vertical, respectively. The collision prediction tested 64620 gantry table combinations in 11.1 seconds. The accuracy was 96.5%, with false positive and negative results occurring at the boundaries of the collision space.Conclusion:Photogrammetry can be used as a tool for collision avoidance during treatment planning. The results indicate that a buffer zone is necessary to avoid false negatives at the boundary of the collision‐free zone. Testing with human patients is underway.Research partially supported by a grant from Varian Medical Systems

A Heuristic Field Navigation Approach for Autonomous Underwater Vehicles

As an effective path planning approach, Potential Field Method has been widely used for Autonomous Underwater Vehicles (AUVs) in underwater probing projects. However, the complexity of the realistic environments (e.g. the three dimensional environments rather than two dimensional environments, and limitations of the sensors in AUVs) have limited most of the current potential field approaches, in which the approaches can only be adapted to theoretic environments such as 2D or static environments. A novel heuristic potential field approach (HPF) incorporating a heuristic obstacle avoidance method is proposed in this paper for AUVs path planning in three dimensional environments which have dynamic targets. The contributions of this paper are: (1) The approach is able to provide solutions for more realistic and difficult conditions (such as three dimensional unknown environments and dynamic targets) rather than hypothetic environments (flat 2D known static environments); (2) The approach results in less compu...

Two-Camera Phase Measuring Profilometry System

The profilometry of three dimensional objectives based on phase approaching of projected grating is widely used in various fields of application engineering. In this paper, two cameras are equipped in our system to obtain fast and static measurement compared to the conventional measuring system with single camera which needs rotated measurement. Algorithm of phase unwrapping based on reliability is also adopted to improve the performance which avoid the breakage of projected grating. Experimental data indicates the measurement error of this Two-camera phase measuring profilimetry system is within 1%. This new profilometry system has great potential application value in the profile measurement of static three dimensional targets.

Thermal anisotropy model for simulated three dimensional urban targets

Thermal anisotropy model for simulated three dimensional urban targets

Evaluation of Inkjet Technologies for Digital Fabrication & Functional Printing

The report determined that the dispensing requirements for digital fabrication and functional printing applications vary widely. Inkjet printing for 3D fabrication requires the deposition of layers that are less than 40 μm along the build Z-axis. Deposit of 30-μm layers for opaque photo polymeric materials and 16-μm layers for transparent polymeric materials have demonstrated that evidence of the layering process is not discernable to the naked eye. The modified Xerox M-series PIJ bend mode head, which has 880 nozzles and ejects drops of 15 or 30 pl, produced even layers and smooth contours without evidence of process artifacts. Similarly, Objet printers using Ricoh Gen3PIJ piston mode printheads produce similarly smooth results, but the production process may require some layer shaving to yield the desired layer thickness. These dimensional targets will satisfy most visual, functional and radiation curing requirements for 3D fabrication applications. The ZPrinters, which use HP TIJ heads to fire polymer into tri-calcium phosphate powder coating, produce Z-layers over 100 μm thick. These typically require some post print curing and finishing.The reports from inkjet printers of electronics indicate that drop volumes of direct printing with metallic nano-particle silver require drops in the range of 1 to 10 pl depending on the refinement of the circuits lines. The Fujifilm Dimatix DMP inkjet print systems have become standard equipment in almost 700 research and development facilities for testing and producing printed circuits. Dimatix offer its 16-nozzle MEMS cartridge printheads in both 1 and 10 pl versions. Other companies have developed similar systems.PixDRO has developed production inkjet systems for fabricating solar cells using a variety of printheads to match process requirements. The Company offers Xaar 1001, Fujifilm Dimatix Spectra S-Class SE, SM, SL, (plus hot melt), SE3 and SX3, Konica Minolta KM 204, KM 256, KM 512 (plus hot melt), Trident ITW 256Jet-D.Acid etching and caustics deposit for some circuit printing approaches requires deposition devices with a wide pH tolerance range. We determined that heads that were stainless steel could provide the greatest pH range. The Trident ITW 256Jet-D head offers tolerances in the pH range of 2 to 13, and the ability for a trained end user to dissemble the head for maintenance.The chemical composition of inkjet printheads must have a surface energy that permits the flow of the print fluid with its surface tension through the head. The fluid must also have a surface tension that permits its adhesion with adjacent build layers. More viscose thermoplastic polymers will typically require heating to lower their viscosity to optimal levels for industrial inkjet printing. Heaters and thermistors are available for most industrial head. In addition to providing consistent temperature for jetting fluids, they can also provide hot melt capability. While Dimatix rates its DMC, D-series and most S-series heads at 70°C it also offers heads with ratings to 135°C. Xerox rates its M-series head as capable of handling fluid to 140°C. The MicroFab MJ-SF piezo dispenser and the Geiger SMLD 300G valve jet are rated to handle fluids up to 250°C. Canon Oce has applied for a patent for an inkjet type device that can tolerate fluid temperatures in excess of 1500°C. The ability to dispense liquids at high temperatures greatly extends the range of what is possible with inkjet fabrication and functional printing.

3D IMAGING METHOD FOR STEPPED FREQUENCY GROUND PENETRATING RADAR BASED ON COMPRESSIVE SENSING

Long data collecting time is one of the bottlenecks of the stepped-frequency continuous-wave ground penetrating radar (SFCW- GPR). We discuss the applicability of the Compressive Sensing (CS) method to three dimensional buried point-like targets imaging for SFCW-GPR. It is shown that the image of the sparse targets can be reconstructed by solving a constrained convex optimization problem based on l1-norm minimization with only a small number of data from randomly selected frequencies and antenna scan positions, which will reduce the data collecting time. Target localization ability, performance in noise, the efiect of frequency bandwidth, and the efiect of the wave travel velocity in the soil are demonstrated by simulated data. Numerical results show that the presented CS method can reconstruct the point-like targets in the right position even with 10% additive Gaussian white noise and some wave travel velocity estimation error.

The closed-form solution of vector finite element integral equations for three dimensional electromagnetic analysis

In this paper, a set of closed-form formulas for vector Finite Element Method (FEM) to analyze three dimensional electromagnetic problems is presented on the basis of Gaussian quadrature integration scheme. By analyzing the open region problems, the first-order Absorbing Boundary Condition (ABC) is considered as the truncation boundary condition and the equation is carried out in a closed-form. Based on the formulas, the hybrid Expanded Cholesky Method (ECM) and MultiFrontal algorithm (MF) is applied to solve finite element equations. Using the closed-form solution, the electromagnetic field of three dimensional targets can be studied sententiously and accurately. Simulation results show that the presented formulas are successfully and concise, which can be easily used to analyze three dimensional electromagnetic problems.

The effect of the Titchener circles illusion on grasping and manual estimation of two and three dimensional targets

The effect of the Titchener circles illusion on grasping and manual estimation of two and three dimensional targets

An efficient surface integral equation method for the time-harmonic Maxwell equations

We present an efficient algorithm to compute high order approximations to the radar cross section (RCS) of a perfectly conducting three dimensional target by solving the time harmonic Maxwell equations. We demonstrate that the algorithm requires only a few tens of thousands of unknowns to compute the RCS of three dimensional targets at medium frequencies. These relatively small linear systems can be solved iteratively or using a direct solver. The possibility of using a direct solver is an advantage in computing the monostatic RCS, which involves solving hundreds of linear systems with one matrix but hundreds of right hand sides. We demonstrate that the monostatic RCS of medium electromagnetic sized conductors can be computed at over one thousand transmitter directions in a few hours of computer time.

Multiple sweep method of moments analysis of electromagnetic scattering from 3D targets on ocean‐like rough surfaces

AbstractThis paper presents the multiple sweep method of moments (MSMM) analysis of electromagnetic (EM) scattering from three dimensional (3D) targets on ocean‐like rough surfaces. The MSMM is a recursive method for solving the large matrix equations which arise in the method of moments (MoM) analysis of electrically large bodies. In the MSMM, the body is split into P sections and the currents on these sections are found in a sequential downrange‐uprange fashion. The first sweep includes the dominant scattering mechanisms and each subsequent sweep includes higher order mechanisms. The results obtained from this study demonstrate that the MSMM is a very reliable and efficient tool for the analysis of this class of problems. The numerical results yield insight into electromagnetic scattering mechanisms associated with a 3D target on a rough surface, and provide accurate and robust reference solutions for more approximate techniques which can handle larger geometries more efficiently. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 241–247, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22074