1,852 research outputs found
Design of approximate overclocked datapath
Embedded applications can often demand stringent latency requirements. While high degrees of parallelism within custom FPGA-based accelerators may help to some extent, it may also be necessary to limit the precision used in the datapath to boost the operating frequency of the implementation. However, by reducing the precision, the engineer introduces quantisation error into the design.
In this thesis, we describe an alternative circuit design methodology when considering trade-offs between accuracy, performance and silicon area. We compare two different approaches that could trade accuracy for performance. One is the traditional approach where the precision used in the datapath is limited to meet a target latency. The other is a proposed new approach which simply allows the datapath to operate without timing closure. We demonstrate analytically and experimentally that for many applications it would be preferable to simply overclock the design and accept that timing violations may arise. Since the errors introduced by timing violations occur rarely, they will cause less noise than quantisation errors.
Furthermore, we show that conventional forms of computer arithmetic do not fail gracefully when pushed beyond the deterministic clocking region. In this thesis we take a fresh look at Online Arithmetic, originally proposed for digit serial operation, and synthesize unrolled digit parallel online arithmetic operators to allow for graceful degradation. We quantify the impact of timing violations on key arithmetic primitives, and show that substantial performance benefits can be obtained in comparison to binary arithmetic. Since timing errors are caused by long carry chains, these result in errors in least significant digits with online arithmetic, causing less impact than conventional implementations.Open Acces
Triply heavy tetraquark states with the configuration
In the framework of the color-magnetic interaction, we systematically
investigate the mass splittings of the tetraquark states and
estimated their rough masses in this work. These systems include the explicitly
exotic states and and the hidden exotic
states , , , and
. If a state around the estimated mass region could be
observed, its nature as a genuine tetraquark is favored. The strong decay
patterns shown here will be helpful to the experimental search for these exotic
states.Comment: 14 pages, 3 figures and 9 tables. Accepted by Eur. Phys. J.
Delay test for diagnosis of power switches
Power switches are used as part of power-gating technique to reduce leakage power of a design. To the best of our knowledge, this is the first work in open-literature to show a systematic diagnosis method for accurately diagnosingpower switches. The proposed diagnosis method utilizes recently proposed DFT solution for efficient testing of power switches in the presence of PVT variation. It divides power switches into segments such that any faulty power switch is detectable thereby achieving high diagnosis accuracy. The proposed diagnosis method has been validated through SPICE simulation using a number of ISCAS benchmarks synthesized with a 90-nm gate library. Simulation results show that when considering the influence of process variation, the worst case loss of accuracy is less than 4.5%; and the worst case loss of accuracy is less than 12% when considering VT (Voltage and Temperature) variations
Salient Object Detection Based on Background Feature Clustering
Automatic estimation of salient object without any prior knowledge tends to greatly enhance many computer vision tasks. This paper proposes a novel bottom-up based framework for salient object detection by first modeling background and then separating salient objects from background. We model the background distribution based on feature clustering algorithm, which allows for fully exploiting statistical and structural information of the background. Then a coarse saliency map is generated according to the background distribution. To be more discriminative, the coarse saliency map is enhanced by a two-step refinement which is composed of edge-preserving element-level filtering and upsampling based on geodesic distance. We provide an extensive evaluation and show that our proposed method performs favorably against other outstanding methods on two most commonly used datasets. Most importantly, the proposed approach is demonstrated to be more effective in highlighting the salient object uniformly and robust to background noise
Control of charging in resonant tunneling through InAs nanocrystal quantum dots
Tunneling spectroscopy of InAs nanocrystals deposited on graphite was
measured using scanning tunneling microscopy, in a double-barrier
tunnel-junction configuration. The effect of the junction symmetry on the
tunneling spectra is studied experimentally and modeled theoretically. When the
tip is retracted, we observe resonant tunneling through the nanocrystal states
without charging. This is in contrast to previous measurements on similar
nanocrystals anchored to gold by linker molecules, where charging took place.
Charging is regained upon reducing the tip-nanocrystal distance, making the
junctions more symmetric. The effect of voltage distribution between the
junctions on the measured spectra is also discussed.Comment: submitte
and as the charmed strange partners of and and the prediction of more members
We relate the interactions of the and systems to those of and
respectively, considering the residual strong
interactions at the near-threshold energy is too weak to excite the strange
quarks inside the hadrons. We propose an effective model to describe the
low-energy S-wave interactions that are undertaken by the light , quarks
between two separated heavy hadrons. We find that the existence of molecules in
the heavy-(anti)heavy sectors will naturally lead to the emergence of molecular
states in and systems. The
recently observed and can be well
identified as the and partners of and
in the charmed strange sector, respectively. We also predict their
members under the {\it heavy} ( and ) quark symmetry and SU(2) flavor
symmetry. Most of them are very good molecule candidates, for example, (i) the
states in , , ;
(ii) the states in , , ; (iii) the state in
and state in . The state in
and the state in might also exist as virtual states, and the
can serve as a key to infer the existence of
. The invariant mass spectrum of is
also studied within the coupled-channel approach, and the molecular
interpretation of is consistent with the experimental
data. Searching for the predicted states in experiments is crucial to
discriminate the different pictures for interpreting these near-threshold
exotica.Comment: 12 pages, 6 figs, and 4 table
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