Search results for "block"
showing 10 items of 1177 documents
3D contour based local manual correction of tumor segmentations in CT scans
2009
Segmentation is an essential task in medical image analysis. For example measuring tumor growth in consecutive CT scans based on the volume of the tumor requires a good segmentation. Since manual segmentation takes too much time in clinical routine automatic segmentation algorithms are typically used. However there are always cases where an automatic segmentation fails to provide an acceptable segmentation for example due to low contrast, noise or structures of the same density lying close to the lesion. These erroneous segmentation masks need to be manually corrected. We present a novel method for fast three-dimensional local manual correction of segmentation masks. The user needs to draw …
Real-time people counting system using a single video camera
2008
This is the copy of journal's version originally published in Proc. SPIE 6811. Reprinted with permission of SPIE: http://spie.org/x10.xml?WT.svl=tn7 There is growing interest in video-based solutions for people monitoring and counting in business and security applications. Compared to classic sensor-based solutions the video-based ones allow for more versatile functionalities, improved performance with lower costs. In this paper, we propose a real-time system for people counting based on single low-end non-calibrated video camera. The two main challenges addressed in this paper are: robust estimation of the scene background and the number of real persons in merge-split scenarios. The latter…
UDP flows in Cognitive Radios with Channel Aggregation and Fragmentation: A Test-bed Based Evaluation
2018
Channel aggregation (CA) and channel fragmentation (CF) have been studied extensively in cognitive radios (CRs) for many years. However, a test-bed evaluation for such techniques at flow level is still open. In this study, employing National Instruments devices, a test-bed is set up to evaluate the performance of UDP flows for CRs with CA and CF, considering the aspects of blocking, preemption, and throughput in probability. The measurements clearly show that there are performance improvements in applying CA and CF in CRs for UDP flows.
European Dissemination of the Ultra-low Temperature Scale, PLTS-2000
2003
The first phase of the EU collaborative project on sub‐kelvin thermometry, ‘ULT Dissemination’, is nearing completion, leading to the development of several thermometers and devices, and the instrumentation needed to disseminate the new Provisional Low Temperature Scale, PLTS‐2000, to users. Principal among these are a current‐sensing noise thermometer (CSNT), a CMN thermometer adapted for industrial use, a Coulomb blockade thermometer, a second‐sound acoustic thermometer and a superconductive reference device SRD‐1000. Several partners have set up 3He melting‐pressure thermometers to realise the PLTS‐2000, and will check it using Pt‐NMR, CMN and other thermometers. The scale, which was for…
Efficiency analysis of burst transmissions with block ACK in contention-based 802.11e WLANs
2005
The channel utilization efficiency of the standard 802.11 networks is severely compromised when high data transmission rates are employed, since physical layer headers and control frames are transmitted at low rate, thus wasting more channel time, proportionally. The extensions defined in the emerging 802.11e for quality-of-service (QoS) provisioning include some new mechanisms developed in order to improve the efficiency. Those include data transmission bursting (referred to as TXOP operation) and acknowledgment aggregation (referred to as block ACK). These two features allow it to offer new data transmission services, in which the data delivery and acknowledgment unit is not a single fram…
Dynamic Flow-Adaptive Spectrum Leasing with Channel Aggregation in Cognitive Radio Networks.
2020
Cognitive radio networks (CRNs), which allow secondary users (SUs) to dynamically access a network without affecting the primary users (PUs), have been widely regarded as an effective approach to mitigate the shortage of spectrum resources and the inefficiency of spectrum utilization. However, the SUs suffer from frequent spectrum handoffs and transmission limitations. In this paper, considering the quality of service (QoS) requirements of PUs and SUs, we propose a novel dynamic flow-adaptive spectrum leasing with channel aggregation. Specifically, we design an adaptive leasing algorithm, which adaptively adjusts the portion of leased channels based on the number of ongoing and buffered PU …
Numerical experiments with a parallel fast direct elliptic solver on Cray T3E
1997
A parallel fast direct O(N log N) solver is shortly described for linear systems with separable block tridiagonal matrices. A good parallel scalability of the proposed method is demonstrated on a Cray T3E parallel computer using MPI in communication. Also, the sequential performance is compared with the well-known BLKTRI-implementation of the generalized. cyclic reduction method using a single processor of Cray T3E.
Spin transport in multilayer systems with fully epitaxial NiO thin films
2018
We report the generation and transport of thermal spin currents in fully epitaxial $\ensuremath{\gamma}\text{\ensuremath{-}}\mathrm{F}{\mathrm{e}}_{2}{\mathrm{O}}_{3}/\mathrm{NiO}(001)/\mathrm{Pt}$ and $\mathrm{F}{\mathrm{e}}_{3}{\mathrm{O}}_{4}/\mathrm{NiO}(001)/\mathrm{Pt}$ trilayers. A thermal gradient, perpendicular to the plane of the sample, generates a magnonic spin current in the ferrimagnetic maghemite $(\ensuremath{\gamma}\text{\ensuremath{-}}\mathrm{F}{\mathrm{e}}_{2}{\mathrm{O}}_{3})$ and magnetite $(\mathrm{F}{\mathrm{e}}_{3}{\mathrm{O}}_{4})$ thin films by means of the spin Seebeck effect. The spin current propagates across the epitaxial, antiferromagnetic insulating NiO layer…
Full angular dependence of the spin Hall and ordinary magnetoresistance in epitaxial antiferromagnetic NiO(001)/Pt thin films
2018
We report the observation of the three-dimensional angular dependence of the spin Hall magnetoresistance (SMR) in a bilayer of the epitaxial antiferromagnetic insulator NiO(001) and the heavy metal Pt, without any ferromagnetic element. The detected angular-dependent longitudinal and transverse magnetoresistances are measured by rotating the sample in magnetic fields up to 11 T, along three orthogonal planes (xy-, yz- and xz-rotation planes, where the z-axis is orthogonal to the sample plane). The total magnetoresistance has contributions arising from both the SMR and ordinary magnetoresistance. The onset of the SMR signal occurs between 1 and 3 T and no saturation is visible up to 11 T. Th…
Direct observation of second-order atom tunnelling
2007
Tunnelling of material particles through a classically impenetrable barrier constitutes one of the hallmark effects of quantum physics. When interactions between the particles compete with their mobility through a tunnel junction, intriguing novel dynamical behaviour can arise where particles do not tunnel independently. In single-electron or Bloch transistors, for example, the tunnelling of an electron or Cooper pair can be enabled or suppressed by the presence of a second charge carrier due to Coulomb blockade. Here we report on the first direct and time-resolved observation of correlated tunnelling of two interacting atoms through a barrier in a double well potential. We show that for we…