1,057 research outputs found
Unsteady adjoint of pressure loss for a fundamental transonic turbine vane
High fidelity simulations, e.g., large eddy simulation are often needed for
accurately predicting pressure losses due to wake mixing in turbomachinery
applications. An unsteady adjoint of such high fidelity simulations is useful
for design optimization in these aerodynamic applications. In this paper we
present unsteady adjoint solutions using a large eddy simulation model for a
vane from VKI using aerothermal objectives. The unsteady adjoint method is
effective in capturing the gradient for a short time interval aerothermal
objective, whereas the method provides diverging gradients for long
time-averaged thermal objectives. As the boundary layer on the suction side
near the trailing edge of the vane is turbulent, it poses a challenge for the
adjoint solver. The chaotic dynamics cause the adjoint solution to diverge
exponentially from the trailing edge region when solved backwards in time. This
results in the corruption of the sensitivities obtained from the adjoint
solutions. An energy analysis of the unsteady compressible Navier-Stokes
adjoint equations indicates that adding artificial viscosity to the adjoint
equations can potentially dissipate the adjoint energy while potentially
maintain the accuracy of the adjoint sensitivities. Analyzing the growth term
of the adjoint energy provides a metric for identifying the regions in the flow
where the adjoint term is diverging. Results for the vane from simulations
performed on the Titan supercomputer are demonstrated.Comment: ASME Turbo Expo 201
Frequency-Doubling of Femtosecond Pulses in “Thick” Nonlinear Crystals With Different Temporal and Spatial Walk-Off Parameters
We present a comparative study on frequency-doubling characteristics of femtosecond
laser pulses in thick nonlinear crystals with different temporal and spatial walk-off
parameters. Using single-pass second harmonic generation (SHG) of 260 fs pulses at
1064 nm from a high-average-power femtosecond Yb-fiber laser in 5-mm-long crystals of
β-BaB2O4 (BBO) and BiB3O6 (BIBO), we find that for comparable values of temporal and
spatial walk-off parameters in each crystal, the optimum focusing condition for SHG is more
strongly influenced by spatial walk-off than temporal walk-off. It is also observed that under
such conditions, the Boyd and Kleinman theory commonly used to define the optimum focusing
condition for frequency-doubling of cw and long-pulse lasers is also valid for SHG
of ultrafast lasers. We also investigate the effect of focusing on the spectral, temporal, and
spatial characteristics of the second harmonic (SH) radiation, as well as angular acceptance
bandwidth for the SHG process, under different temporal and spatial walk-off conditions in
the two crystalsPeer ReviewedPostprint (author's final draft
Krasovskii's Passivity
In this paper we introduce a new notion of passivity which we call
Krasovskii's passivity and provide a sufficient condition for a system to be
Krasovskii's passive. Based on this condition, we investigate classes of
port-Hamiltonian and gradient systems which are Krasovskii's passive. Moreover,
we provide a new interconnection based control technique based on Krasovskii's
passivity. Our proposed control technique can be used even in the case when it
is not clear how to construct the standard passivity based controller, which is
demonstrated by examples of a Boost converter and a parallel RLC circuit
Social Media in Steel Industry: Digital Marketing
These days Social Media is a go to platform to check and analyze reports regarding any products before actually purchasing. It has a swift and improved way to gather all the required information at one place. The content that has to be received by the customers or the solutions that has to be provided by the industries, can be obtained in a single platform in other words it is best fit for all the customer's needs. Now a day, steel companies not only invest in share markets (or) ad agencies but also on social platform where the awareness spreads to a crowd of people in very less time. In this digital era with all these rapid changing periods, the steel industry will have to constantly raise in its communications process. With the immense growth of social media marketing and online outsourcing, major steel industries are approaching social networking platforms to get their work done ( I.e. spreading awareness across the country from one place). After the introduction of social marketing, promotions has become lot easier and can receive real time analysis of everything on how the product is working, because of which company can rectify all the lacks and present mistake-free project to the customers. Also, social media marketing focuses on targeted people. One of the main purpose of introducing social media in steel industry is that breaking 'long standing' stereotypes and reaching out to people in a lot easier way
Borrow from Anywhere: Pseudo Multi-modal Object Detection in Thermal Imagery
Can we improve detection in the thermal domain by borrowing features from
rich domains like visual RGB? In this paper, we propose a pseudo-multimodal
object detector trained on natural image domain data to help improve the
performance of object detection in thermal images. We assume access to a
large-scale dataset in the visual RGB domain and relatively smaller dataset (in
terms of instances) in the thermal domain, as is common today. We propose the
use of well-known image-to-image translation frameworks to generate pseudo-RGB
equivalents of a given thermal image and then use a multi-modal architecture
for object detection in the thermal image. We show that our framework
outperforms existing benchmarks without the explicit need for paired training
examples from the two domains. We also show that our framework has the ability
to learn with less data from thermal domain when using our approach. Our code
and pre-trained models are made available at
https://github.com/tdchaitanya/MMTODComment: Accepted at Perception Beyond Visible Spectrum Workshop, CVPR 201
Neural Decoder for Topological Codes using Pseudo-Inverse of Parity Check Matrix
Recent developments in the field of deep learning have motivated many
researchers to apply these methods to problems in quantum information. Torlai
and Melko first proposed a decoder for surface codes based on neural networks.
Since then, many other researchers have applied neural networks to study a
variety of problems in the context of decoding. An important development in
this regard was due to Varsamopoulos et al. who proposed a two-step decoder
using neural networks. Subsequent work of Maskara et al. used the same concept
for decoding for various noise models. We propose a similar two-step neural
decoder using inverse parity-check matrix for topological color codes. We show
that it outperforms the state-of-the-art performance of non-neural decoders for
independent Pauli errors noise model on a 2D hexagonal color code. Our final
decoder is independent of the noise model and achieves a threshold of .
Our result is comparable to the recent work on neural decoder for quantum error
correction by Maskara et al.. It appears that our decoder has significant
advantages with respect to training cost and complexity of the network for
higher lengths when compared to that of Maskara et al.. Our proposed method can
also be extended to arbitrary dimension and other stabilizer codes.Comment: 12 pages, 12 figures, 2 tables, submitted to the 2019 IEEE
International Symposium on Information Theor
AN FPGA IMPLEMENTATION OF MODIFIED DECISION BASED UNSYMMETRICAL TRIMMED MEDIAN FILTER FOR THE REMOVAL OF SALT AND PEPPER NOISE IN DIGITAL IMAGES
A modified decision based unsymmetrical trimmed median filter algorithm for the restoration of gray scale, and color images that are highly corrupted by salt and pepper noise is proposed in this paper. Images are often corrupted by impulse noise during acquisition and transmission; thus, an efficient noise suppression technique is required before subsequent image processing operations. Median filter (MF) is widely used in noise removal methods due to its denoising capability and computational efficiency. However, it is effective only for low noise densities. Extensive experimental results demonstrate that our method can obtain better performances in terms of both subjective and objective evaluations than denoising techniques. Especially, the proposed method can preserve edges very well while removing salt and pepper noise. Modified Decision Based Algorithm (MDBA), and Progressive Switched Median Filter (PSMF) shows better results at low and medium noise densities. At high noise densities, their performance is poor. A new algorithm to remove high-density salt and pepper noise using modified Decision Based Unsymmetric Trimmed Median Filter (DBUTMF) is proposed. The proposed algorithm replaces the noisy pixel by trimmed median. Since our algorithm is algorithmically simple, it is very suitable to be applied to many real-time applications and higher noise densities. When all the pixel values are 0’s and 255’s then the noise pixel is replaced by mean value of all the elements present in the selected window. The proposed algorithm is tested against different grayscale and color images and it gives better Peak Signal-to-Noise Ratio (PSNR) and Image Enhancement Factor (IEF)
Maternal mortality at a government teaching hospital: a six year duration study
Background: The studies were to help generate information and knowledge regarding the causes of maternal deaths in an urban tertiary health care government hospital and how they can be prevented in a developing country like ours to achieve millennium development goal 5 (MDGS) at reducing the MMR by 75% over the period of 1990-2015.Methods: A retrospective study done in the year of 2014 on 97 maternal deaths over a period of six years from January 2007 to December 2012.Results: During the study period there were 16,534 deliveries, and 97 maternal deaths, giving a maternal mortality rate of 586/100,000 live births. Haemorrhage was leading cause of death. Most women died within 24 hours of admission and most of them were admitted in shock. The majority of the death occurred in the age group 20-30 years and in multigravidas.Conclusions: The maternal mortality rate is much more than the national MMR. Haemorrhage was the leading cause of death followed by septicemia, both of them being preventable by adequate transfusion of blood and its components, delivery in a well-equipped hospital, early identification and prompt action, good antibiotic coverage, and early transportation
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