| 1. |
- Elsakka, Amr, et al.
(författare)
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A mm-Wave Phased-Array Fed Torus Reflector Antenna with ±30° Scan Range for Massive-MIMO Base-Station Applications
- 2022
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Ingår i: IEEE Transactions on Antennas and Propagation. - 0018-926X .- 1558-2221. ; 70:5, s. 3398-3410
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Tidskriftsartikel (refereegranskat)abstract
- A phased-array fed reflector antenna system is presented which can be used for mm-wave base station applications. The proposed system is designed to support massive-Multi-Input-Multi-Output (MIMO) scenarios within a wide coverage (±30°) in the azimuth plane and a limited coverage at the elevation plane. A design and characterization methodology has been established to optimize the system for the operation in various line-of-sight conditions by adopting the maximum-ratio-transmission (MRT) and zero-forcing (ZF) MIMO algorithms. A two-user MIMO case study has been considered for the evaluation of the key system performance metrics, i.e. the effective isotropic radiated power, power consumption, signal-to-noise-ratio (SNR), and signal-to-interference-plus-noise-ratio (SINR). This study demonstrates that the phased-array fed reflector concept has a major advantage over traditional direct-radiating phased array (DRPA) antennas to reduce energy consumption. In the present example, it requires 12–14 dB less transmitted power as compared to the MRT-beamformed DRPAs for the same SNR, and 26–27 dB less transmitted power relatively to ZF-beamformed DRPA systems for the same SINR. A prototype, employing a 55 cm diameter torus reflector and operating at 28 GHz-band, has been manufactured and tested. The measurement results agree well with simulations.
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| 2. |
- Ribero-Rotta, Rejane Faria, et al.
(författare)
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Ambiguity in bone tissue characteristics as presented in studies on dental implant planning and placement : a systematic review
- 2011
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Ingår i: Clinical Oral Implants Research. - : Wiley. - 0905-7161 .- 1600-0501. ; 22:8, s. 789-801
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Tidskriftsartikel (refereegranskat)abstract
- Objectives: To survey definitions of bone tissue characteristics and methods of assessing them in studies of dental implant planning and placement. Material and methodology: Three databases were searched using specified indexing terms. Three reviewers selected from the titles and retrieved abstracts in accordance with inclusion and exclusion criteria. Descriptions of bone tissue characteristics (bone quality, density and quantity) used before or during dental implant placement were searched for and categorized. Results: The search yielded 488 titles. One hundred and fort-nine publications were selected and read in full text. One hundred and eight were considered relevant. There were many different definitions and classification systems for bone tissue characteristics and examination protocols. Approximately two-third of the included publications reported the Lekholm & Zarb classification system for bone quality and quantity. However, only four studies implemented the Lekholm & Zarb system as originally proposed. A few publications described bone quality in accordance with the Misch or Trisi and Rao classifications systems. Assessment methods were often described only briefly (or not at all in one-fifth of the publications). Only one study presented the diagnostic accuracy of the assessment method, while only two presented observer performance. Conclusion: The differing definitions and classification systems applied to dental implant planning and placement make it impossible to compare the results of various studies, particularly with respect to whether bone quality or quantity affect treatment outcomes. A consistent classification system for bone tissue characteristics is needed, as well as an appropriate description of bone tissue assessment methods, their diagnostic accuracy and observer performance. To cite this article:
Ribeiro-Rotta RF, Lindh C, Pereira AC, Rohlin M. Ambiguity in bone tissue characteristics as presented in studies on dental implant planning and placement: a systematic review.
Clin. Oral Impl. Res. xx, 2010; 000-000.
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| 3. |
- Ribes, Stefano, 1992, et al.
(författare)
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Mapping Multiple LSTM models on FPGAs
- 2020
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Ingår i: Proceedings - 2020 International Conference on Field-Programmable Technology, ICFPT 2020. ; , s. 1-9
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Konferensbidrag (refereegranskat)abstract
- Recurrent Neural Networks (RNNs) and their more recent variant Long Short-Term Memory (LSTM) are utilised in a number of modern applications like Natural Language Processing and human action recognition, where capturing longterm dependencies on sequential and temporal data is required. However, their computational structure imposes a challenge when it comes to their efficient mapping on a computing device due to its memory-bounded nature. As recent approaches aim to capture longer dependencies through the utilisation of Hierarchical and Stacked RNN/LSTM models, i.e. models that utilise multiple LSTM models for prediction, meeting the desired application latency becomes even more challenging. This paper addresses the problem of mapping multiple LSTM models to a device by introducing a framework that alters their computational structure opening opportunities for co-optimising the memory requirements to the target architecture. Targeting an FPGA device, the proposed framework achieves 3× to 5× improved performance over state-of-The-Art approaches for the same accuracy loss, opening the path for the deployment of high-performance systems for Hierarchical and Stacked LSTM models.
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| 4. |
- Asplund, Matthias, et al.
(författare)
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- 2016
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Ingår i: Measurement. - : Elsevier BV. - 0263-2241 .- 1873-412X. ; 92, s. 19-27
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Tidskriftsartikel (refereegranskat)abstract
- Reliable data with less variation play a key role for acceptance of the usefulness of the measurement output of a wheel profile measurement system (WPMS) in a railway network. However, in practice, most studies are carried out without checking the reliability of data from such a system, which may lead to inappropriate maintenance strategies. To ensure the measurement capability of WPMS and to support robust maintenance in railway systems, this study has evaluated measurement data for the flange height, flange thickness, flange slope, and tread hollowing of rolling stock wheels by using gauge repeatability and reproducibility (GR&R). In this study, acceptance and rejection criteria for the precision-to-tolerance ratio (PTR), signal-to-noise ratio (SNR), and discrimination ratio (DR) have been employed to evaluate the measurement capabilities. For the purpose of illustration, we have implemented a new proposed approach. This approach involves both an analysis using graphs with four regions with a confidence interval (CI) of 95% and an analysis using a graph with three regions with only the predicted values; the latter type of graph represents an innovation made in this study. The results show that the measurements of the tread hollowing and flange slope are on an acceptable level, while those for the flange height and flange thickness have to be rejected as unacceptable. The action proposed to increase the quality of data on the flange height and flange thickness is to enhance the calibration of the WPMS. In conclusion, GR&R is a useful tool to evaluate the measurement capability of WPMS and to provide helpful support for maintenance decision making.
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