backscatter

Abstract. Distributed denial of service (DDoS) attacks are a serious problem in the present-day Internet. We consider the design of a scalable agent-based system for collecting information about the structure and dynamics of DDoS attacks. Our system requires ...

Micro-Doppler analysis concerns the extraction and exploitation of time-varying Doppler frequency shifts produced by mechanical oscillations of a target or target components. Examples of oscillatory motion include mechanical displacements or vibrations of target surfaces, rotations of target components, target spin, precession, or nutation. Such periodic motion modulates the Doppler frequency shift produced by translational motion and manifests itself as localized and time-varying Doppler frequency sidebands. In this paper, we will discuss methods for analyzing, visualizing, and exploiting these micro-Doppler signatures, and present examples of micro-Doppler signatures resulting from both rigid and nonrigid body micro-motion. Appropriate physical motion models will be described and applied to computational electromagnetic tools that generate simulated radar backscattering. Joint time-frequency signal representations will be used to visualize these signatures. We will also discuss ch...

Wireless video streaming has traditionally been considered an extremely power-hungry operation. Existing approaches optimize the camera and communication modules individually to minimize their power consumption. However, designing a video streaming device requires power-consuming hardware components and video CODEC algorithms which makes battery-free video streaming currently infeasible. Existing RF-powered wireless camera prototypes require extensive duty-cycling on the order of tens of minutes, to capture , process and communicate a single frame. Self-powered cameras can capture an image once every few seconds, but do not have the capability to stream video wirelessly. To understand this case, let us look at the different components in a video-streaming device 1(a): optical lens, video compression and communication. Optical lens is an array of photo-diodes connected to amplifiers and an ADC to translate the analog pixels into digital values. A video CODEC then performs frame compression to compress video, which is then transmitted on the wireless medium. Existing approaches optimize the camera and communication modules separately to minimize their power consumption. However, designing a video streaming device requires power consuming hardware components and video CODEC algorithms that interface the camera and the communication modules. We present the design of an ultra-low-power video streaming device 1(b). We create " analog " video backscatter system that does not use amplifiers, ADCs and AGCs. At a high level, we feed analog pixels from the photo-diodes directly to the backscatter hardware. We achieve this by connecting the antenna to an array of photo-diodes whose output voltage/impedance varies as a function of the pixel value; thus, eliminate power-hungry hardware components including amplifiers, AGCs and ADCs. Such an approach would have the added benefit that the video quality scales smoothly with a varying wireless channel, without the need for explicit rate adaptation. We present our video streaming architecture with more details in [1, 2]. We implement a prototype of our backscatter design on an ultra-low power FPGA platform using a 112×112 gray-scale random pixel access camera from CentEye, which provides readout access to the individual analog pixels. The proto

The strong dependence of tendon echogenicity on insonation angle is explored by analyzing echo spectra. Combining echo spectra with high-resolution images from several modalities reveals that fluid spaces surrounding fascicles and bundles are likely sources of ultrasonic scatter. Mathematical models of tendon structure are proposed to explain how the anisotropic microstructure of tendon gives rise to angle-dependent echogenicity. Echo spectra from spontaneously damaged equine tendon samples were compared with normal equine tendon and found to exhibit a dramatic decrease in anisotropic properties that appears to be related to the spatial organization and type of collagen generated during repair. Variation in echo spectra with insonation angle is a robust indicator of mechanical damage. (E-mail: wjhornof@ucdavis.edu) © 2003 World Federation for Ultrasound in Medicine & Biology.

The presently studied numerical model, eg, composite roughness, is successful for the purpose of seafloor classification employing processed multibeam angular backscatter data from manganese-nodule-bearing locations of the Central Indian Ocean Basin. Hybrid ...

A first evaluation of ALOS PALSAR data for forest stem volume estimation has been performed at a coniferous dominated test site in Sweden. In total, 7 Fine Beam Single polarization (FBS, look angle 34.3deg, HH-polarization) and 7 Polarimetric (PLR, look angle 21.5deg, HH-, HV-, VH-, and W- polarization) SAR images were used. In total, 56 forest stands with stem volume

The numeric inversion of water-cloud model of synchronized microwave bands of ERS-2 and JERS satellites gave the possibility of obtaining crop characteristics. Model performance was validated by comparison between backscattering coefficients simulated and measured by satellites. The contribution of various crop characteristics was presented and compared to measured soil-vegetation parameters at the ground level during satellite overpasses.

Abstract—The physical basis for breast tumor detection with microwave imaging is the contrast in dielectric properties of normal and malignant breast tissues. Confocal microwave imaging involves illuminating the breast with an ultra-wideband pulse from a number of antenna ...

The nature of the surface in a flat arid zone located in the western Sahara desert was studied and its roughness parameters defined. The main geological units were compared with backscattering data from ERS-1 images. Results showed a close correlation between the backscattering coefficient, σ0, and the maximum height, hmax, of the rocks making up the arid landscape. The simplified

ABSTRACT Denial-of-service attacks are the second most costly type of computer crime, after viruses, according to the 2008 Computer Security Institute survey of security professional's at large organizations. Until recently, denial-of-service attacks were usually weapons used by novice attackers in vendettas against enemies. But like other types of malicious activity on the Internet, attackers increasingly appear to be members of criminal enterprises with financial motives. This paper focuses on techniques that can be used to identify the attackers based on tracing back flows.

Traditional metrology solutions are facing a range of challenges at the 1X node such as three dimensional (3D) measurement capabilities, shrinking overlay and critical dimension (CD) error budgets driven by multi-patterning and via in trench CD measurements. Hybrid metrology offers promising new capabilities to address some of these challenges but it will take some time before fully realized. This paper explores new capabilities currently offered on the in-line Critical Dimension Scanning Electron Microscope (CD-SEM) to address these challenges and enable the CD-SEM to move beyond measuring bottom CD using top down imaging. Device performance is strongly correlated with Fin geometry causing an urgent need for 3D measurements. New beam tilting capabilities enhance the ability to make 3D measurements in the front-end-of-line (FEOL) of the metal gate FinFET process in manufacturing. We explore these new capabilities for measuring Fin height and build upon the work communicated last year at SPIE1. Furthermore, we extend the application of the tilt beam to the back-end-of-line (BEOL) trench depth measurement and demonstrate its capability in production targeting replacement of the existing Atomic Force Microscope (AFM) measurements by including the height measurement in the existing CDSEM recipe to reduce fab cycle time. In the BEOL, another increasingly challenging measurement for the traditional CD-SEM is the bottom CD of the self-aligned via (SAV) in a trench first via last (TFVL) process. Due to the extremely high aspect ratio of the structure secondary electron (SE) collection from the via bottom is significantly reduced requiring the use of backscatter electrons (BSE) to increase the relevant image quality. Even with this solution, the resulting images are difficult to measure with advanced technology nodes. We explore new methods to increase measurement robustness and combine this with novel segmentation-based measurement algorithm generated specifically for BSE images. The results will be contrasted with data from previously used methods to quantify the improvement. We also compare the results to electrical test data to evaluate and quantify the measurement performance improvements. Lastly, according to International Technology Roadmap for Semiconductors (ITRS) from 2013, the overlay 3 sigma requirement will be 3.3 nm in 2015 and 2.9 nm in 2016. Advanced lithography requires overlay measurement in die on features resembling the device geometry. However, current optical overlay measurement is performed in the scribe line on large targets due to optical diffraction limit. In some cases, this limits the usefulness of the measurement since it does not represent the true behavior of the device. We explore using high voltage imaging to help address this urgent need. Novel CD-SEM based overlay targets that optimize the restrictions of process geometry and SEM technique were designed and spread out across the die. Measurements are done on these new targets both after photolithography and etch. Correlation is drawn between the two measurements. These results will also be compared to conventional optical overlay measurement approaches and we will discuss the possibility of using this capability in high volume manufacturing.

Stimulated Raman backscattering in plasma has been suggested as a way to amplify short laser pulses to intensities not limited by damage thresholds as in chirped pulse amplification using conventional media. Energy is transferred between two transverse electromagnetic ...

In the context of remotely sensed data analysis, an important problem is the development of accurate models for the statistics of the pixel intensities. Focusing on synthetic aperture radar (SAR) data, this modeling process turns out to be a crucial task, ...