66 research outputs found
Low Complexity Belief Propagation Polar Code Decoders
Since its invention, polar code has received a lot of attention because of
its capacity-achieving performance and low encoding and decoding complexity.
Successive cancellation decoding (SCD) and belief propagation decoding (BPD)
are two of the most popular approaches for decoding polar codes. SCD is able to
achieve good error-correcting performance and is less computationally expensive
as compared to BPD. However SCDs suffer from long latency and low throughput
due to the serial nature of the successive cancellation algorithm. BPD is
parallel in nature and hence is more attractive for high throughput
applications. However since it is iterative in nature, the required latency and
energy dissipation increases linearly with the number of iterations. In this
work, we borrow the idea of SCD and propose a novel scheme based on
sub-factor-graph freezing to reduce the average number of computations as well
as the average number of iterations required by BPD, which directly translates
into lower latency and energy dissipation. Simulation results show that the
proposed scheme has no performance degradation and achieves significant
reduction in computation complexity over the existing methods.Comment: 6 page
Posterior Mediastinal Chondrosarcoma- A rare entity
Introduction:Chondrosarcoma is a well defined tumor of soft tissue with calcification. Extraskeletal myxoid chondrosarcoma is an unusual sarcoma of soft tissue adding only 3% to all soft tissue tumors. Majority of mediastinal foci originates from variety of tissues, the reason being their diverse embryological and anatomical approximations. Chondrosarcomas are more common in males with 2:1 male to female ratio. The exact pathology of these tumors is unclear; however recent data ensures that these tumors have multidirectional delineation. Classical histopathological features of chondrosarcoma include S-100 positivity, EMA positivity. These features of Immunohistochemical favor extra skeletal myxoid chondrosarcoma.Case Report:Recent data signifies that the tumor is known for its rare occurrence, here we have reported a unique case of 40 years old male visited Abbasi Shaheed Hospital for pre employment checkup without any symptoms. All the tests were negative except Chest X-ray PA view which revealed dense mass on lower lobe of lung. For further evaluation, CT scan of chest with contrast was ordered and eventually the mass was resected surgically. On the basis of macro and microscopic findings, histopathological tests and immunohistochemical stains, the mass was found to be chondrosarcoma with myxoid origin. This tumor has to be distinguishing among the list of different diseases like hamartoma, hydatid cyst, and neuroendocrine tumors for the differential diagnosis of the case.Conclusion: Our paper reports an extraskeletal mesenchymal chondrosarcoma originating in the posterior mediastinum with a rare presentation.Â
A simplified finite element model for assessing steel fibre reinforced concrete structural performance
The present numerical investigation offers evidence concerning the validity and objectivity of the predictions of a simple, yet practical, finite element model concerning the responses of steel fibre reinforced concrete structural elements under static monotonic and cyclic loading. Emphasis is focused on realistically describing the fully brittle tensile behaviour of plain concrete and the contribution of steel fibres on the post-cracking behaviour it exhibits. The good correlation exhibited between the numerical predictions and their experimental counterparts reveals that, despite its simplicity, the subject model is capable of providing realistic predictions concerning the response of steel fibre reinforced concrete structural configurations exhibiting both ductile and brittle modes of failure without requiring recalibration
Seismic response of steel fibre reinforced concrete beam-column joints
The present research work aims to investigate numerically the behaviour of steel fibre
reinforced concrete beam-column joints under seismic action. Both exterior and interior joint
types were examined and 3D nonlinear finite element analyses were carried out using
ABAQUS software. The joints were subjected to reversed-cyclic loading, combined with a
constant axial force on the column representing gravity loads. The joints were initially
calibrated using existing experimental data – to ascertain the validity of the numerical model
used – and then parametric studies were carried out using different steel fibre ratios coupled
with increased spacing of shear links. The aim was to assess the effect of introducing steel
fibres into the concrete mix in order to compensate for a reduced amount of conventional
transverse steel reinforcement and hence lessen congestion of the latter. This is particularly
useful for joints designed to withstand seismic loading as code requirements (e.g. Eurocode
8) lead to a high amount of shear links provided to protect critical regions. The spacing
between shear links was increased by 0%, 50% and 100%, whilst the fibre volume fraction (Vf)
was increased by 0%, 1%, 1.5%, 2% and 2.5%. Potential enhancement to ductility, a key
requirement in seismic design, was investigated as well as potential improvements to energy
absorption and confinement. The work also examined key structural issues such as strength,
storey drift, plastic hinges formation and cracking patterns
Step-GRAND: A Low Latency Universal Soft-input Decoder
GRAND features both soft-input and hard-input variants that are well suited
to efficient hardware implementations that can be characterized with achievable
average and worst-case decoding latency. This paper introduces step-GRAND, a
soft-input variant of GRAND that, in addition to achieving appealing average
decoding latency, also reduces the worst-case decoding latency of the
corresponding hardware implementation. The hardware implementation results
demonstrate that the proposed step-GRAND can decode CA-polar code
with an average information throughput of Gbps at the
target FER of . Furthermore, the proposed step-GRAND hardware is
more area efficient than the previous soft-input ORBGRAND hardware
implementation, and its worst-case latency is that of the
previous ORBGRAND hardware.Comment: Submitted to 2023 IEEE Globecom Workshop
Delayed presentation of forgotten thyroid goiter - 25 years after thyroidectomy
Forgotten goiter is a rare occurrence (2 - 16% of retrosternal thyroid cases) that depicts recurrence of retrosternal thyroid mass due to growth of remnant thyroid tissue overlooked during an initial thyroidectomy. The patient is a 59-year female who presented with dyspnea and stridor 25 years after total thyroidectomy. She was diagnosed as having a mediastinal mass on radiographic imaging. There were only localized pressure symptoms due to mass effect. The mass was excised employing an extra-cervical approach and using a partial sternotomy. The profuse extension of thyroid tissue, adherent to vital structures in the thorax and the extra-cervical thyroidectomy was a novel experience. The mass was completely excised and the patient\u27s symptoms alleviated after the surgery. The patient recovered without any complications and there was no recurrence at 1 year of follow-up
Shear behaviour of steel-fibre-reinforced concrete simply supported beams
The structural behaviour of steel-fibre-reinforced concrete beams was studied using non-linear finite-element analysis
and existing experimental data. The work aim was to examine the potential of using steel fibres to reduce the
amount of conventional transverse steel reinforcement without compromising ductility and strength requirements set
out in design codes. To achieve this, the spacing between shear links was increased while steel fibres were added as a
substitute. Parametric studies were subsequently carried out and comparisons were also made with BS EN 1992-1-1
predictions. It was concluded that the addition of steel fibres enhanced the load-carrying capacity and also altered
the failure mode from a brittle shear mode to a flexural ductile one. The provision of fibres also improved ductility.
However, interestingly it was found that adding excessive amounts of fibres led to a less-ductile response. Overall,
the study confirmed the potential for fibres to compensate for a reduction in conventional shear reinforcement
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