1,720,975 research outputs found
Ekho: A 30.3W, 10k-Channel Fully Digital Integrated 3-D Beamformer for Medical Ultrasound Imaging Achieving 298M Focal Points per Second
No full text3-D medical ultrasound imaging enables new diagnostic possibilities and modalities. In a computational process called beamforming, a 3-D volume is reconstructed from several thousands of analog signals. Today's systems rely on massive analog preprocessing to reduce the computational burden of the subsequent digital processing system. In this paper, we present a configurable beamformer (BF) architecture, which demonstrates for the first time that it is possible to implement the entire 3-D delay and sum beamforming fully digitally and on one single chip, without requiring the off-chip memories. We present a presilicon implementation of a single-chip BF in an advanced 28-nm silicon-on-insulator technology. The BF targets a fully sampled 10k element 8-MHz bandwidth transducer head and is able to produce 298.1M focal points (FPs) per second - enough to produce a high-resolution volume with 16.3MFP at 15 Hz. All delays are computed online and on-chip to eliminate the power-hungry external memories for delay storage. The final design (register-transfer-level and floorplan) has a complexity of 342M gate equivalents requiring 1.68cm2 of area. The core power is estimated to be 30.3 W, resulting in an unprecedented power efficiency of 98.4G beamforming operations per watt
CAS-CNN: A deep convolutional neural network for image compression artifact suppression
Full text linkLossy image compression algorithms are pervasively used to reduce the size of images transmitted over the web and recorded on data storage media. However, we pay for their high compression rate with visual artifacts degrading the user experience. Deep convolutional neural networks have become a widespread tool to address high-level computer vision tasks very successfully. Recently, they have found their way into the areas of low-level computer vision and image processing to solve regression problems mostly with relatively shallow networks. We present a novel 12-layer deep convolutional network for image compression artifact suppression with hierarchical skip connections and a multi-scale loss function. We achieve a boost of up to 1.79 dB in PSNR over ordinary JPEG and an improvement of up to 0.36 dB over the best previous ConvNet result. We show that a network trained for a specific quality factor (QF) is resilient to the QF used to compress the input image - a single network trained for QF 60 provides a PSNR gain of more than 1.5 dB over the wide QF range from 40 to 76
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
LightProbe: A fully-digital 64-channel ultrasound probe with high-bandwidth optical interface
No full textA typical medical ultrasound-imaging system consists of a passive probe and a backend system containing the analog frontend and the digital processing unit, to which the probe connects over a coaxial cable harness. Digital processing is increasingly performed in software on powerful GPUs or multicore CPUs. These new system architectures have not only enabled new imaging modalities (Ultrafast Imaging, Vector Flow Estimation), but also reduced system cost, as ultrasound specific hardware is only used for the acquisition of the raw signals. The next step in this evolution are fully-digital ultrasound probes, which integrate the analog frontend and are equipped with a standard digital interface. This allows connecting the probe directly to a standard device, such as a workstation, tablet or mobile phone running an ultrasound software application. So far, this concept has been demonstrated for mobile applications, but is currently limited to a small number of frontend channels (â1⁄416) due to the large digital bandwidth (>10 Gb/s) at the interface between the probe and the mobile device
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
UltraLight: An ultrafast imaging platform based on a digital 64-channel ultrasound probe
No full textDigital ultrasound probes include the entire analog frontend in their enclosing and are equipped with a standard digital link. This enables to build very cost-effective ultrasound systems as they can be simply connected to a commodity device, such as a desktop PC, tablet or smartphone, running an ultrasound imaging application. Up to now, digital probes have been mainly demonstrated for low-end ultrasound applications and are currently limited to a small number of frontend channels (typically 16). In addition, the available bandwidth at the digital interface (less than 10 Gb/s) limits these devices only to basic imaging modalities. In this work, we present an imaging platform built with a digital 64-channel ultrasound probe that supports ultrafast imaging. Our digital probe, called LightProbe, utilizes a 64-element phased array without multiplexing and incorporates a 64-channel 100 Vpp TX/RX stage providing a sample rate up to 32.5 MS/s @ 12bit. The probe features an optical link interface achieving 25Gb/s on a standard fiber cable. A Xilinx Artix 7 FPGA is integrated in the probe to manage the optical interface and to provide a high-degree of configurabilty. To the best of our knowledge, this is the first digital probe capable of compounded plane wave imaging. We capture plane waves with peak and average rate of 4.9 kHz and 2kHz respectively, with a peak link load of 15.36 Gb/s, while consuming just 9.25 W
LightProbe: A 64-channel programmable ultrasound transducer head with an integrated front-end and a 26.4 Gb/s optical link
No full textMedical ultrasound processing features two main components: A transducer head to generate the ultrasound wave and acquire the reflected signals and a processing system that will generate the final image. The connection between these two components is established using digital communication over a USB link for smaller mobile systems whereas large stationary systems operating with 4-16x more channels use analog signals over micro-coaxial cables to avoid link rates of 16-100 Gb/s. In this paper, we present LightProbe, a programmable ultrasound transducer head with an integrated 64-channel frontend and operating on an estimated 12 W worst-case power budget. LightProbe is the first transducer head equipped with a 26.4 Gb/s optical link. Moreover, it features a configurable FPGA that can be configured to pre-process the data on the transducer head and allows a flexible, inexpensive, light digital optical link that is immune to interference and can be tailored to fit a variety of devices from small mobile devices all the way to large stationary devices with high throughput requirements
Assessing the area/power/performance tradeoffs for an integrated fully-digital, large-scale 3D-ultrasound beamformer
Full text linkHigh-frame-rate and high-resolution 3D medical ultrasound imaging imposes high requirements on the involved processing hardware. Several thousands of analog signals need to be processed in many steps to obtain a final image. Fully digital beamforming makes it possible to achieve high image quality coupled with extreme flexibility. Unfortunately, digital beamforming imposes staggering requirements on main memory bandwidth caused by the loading of off-chip stored beamforming delays. In this paper we present the first fully-digital integrated beamformer that is able to compute 269.3 M focal points (FP) per second from 10 000 receive channels, and which does not require off-chip main memory. This is enabled by our novel delay approximation circuit that exploits temporal correlation between subsequent computations and thereby allows to compute the delays for beamforming online. To estimate the area and power requirements, the complete system was designed and the beamformer core was evaluated for a 130 nm CMOS technology. The estimated complexity per channel is 37.2 kGE and the corresponding power dissipation was estimated with 48 mW
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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