2,247 research outputs found
Experimental investigation of the radial structure of energetic particle driven modes
Alfv\'en eigenmodes (AEs) and energetic particle modes (EPMs) are often
excited by energetic particles (EPs) in tokamak plasmas. One of the main open
questions concerning EP driven instabilities is the non-linear evolution of the
mode structure. The aim of the present paper is to investigate the properties
of beta-induced AEs (BAEs) and EP driven geodesic acoustic modes (EGAMs)
observed in the ramp-up phase of off-axis NBI heated ASDEX Upgrade (AUG)
discharges. This paper focuses on the changes in the mode structure of
BAEs/EGAMs during the non-linear chirping phase. Our investigation has shown
that in case of the observed down-chirping BAEs the changes in the radial
structure are smaller than the uncertainty of our measurement. This behaviour
is most probably the consequence of that BAEs are normal modes, thus their
radial structure strongly depends on the background plasma parameters rather
than on the EP distribution. In the case of rapidly upward chirping EGAMs the
analysis consistently shows shrinkage of the mode structure. The proposed
explanation is that the resonance in the velocity space moves towards more
passing particles which have narrower orbit widths.Comment: submitted to Nuclear Fusio
Benign papillary cystadenofibroma of fallopian tube presenting as posterior fornix cyst: case report
Benign papillary cystadenofibroma of fallopian tube is very rare tumor of female genital tract. Usually asymptomatic and incidental finding. Worldwide literature only 18 cases were found. On account of its rarity and best of our knowledge, is the first case of benign papillary cystadenofiboma presented as posterior fornix cyst, so we are presenting this case. We report a rare case of benign papillary cystadenofibroma of fallopian tube in a 30-years old female P3L3 presenting with abdominal pain. On examination abdomen was soft, per vaginally mobile non-tender cystic mass of 5×4 cm was noted. Laparotomy was planned. Intraoperatively 5x4 cm cyst arising from serosal surface of left fallopian tube near fimbrial end noted with bilateral ovaries normal. Left fimbrial cystectomy with salpingectomy was done with sparing both ovaries. Histopathology suggestive of benign papillary cystadenofibroma of fallopian tube. Patient had uneventful recovery in follow up period. Benign papillary cystadenofibroma of fallopian tube is rare tumor found incidentally. Tumor seems to have benign course only cystectomy is required for treatment
Analisis Peranan Perempuan Pada Rantai Nilai Pemasaran Tuna Cakalang Di Tempat Pelelangan Ikan (Tpi) Aertembaga Kota Bitung
Penelitian ini dilaksanakan di Tempat Pendaratan Ikan (TPI) Aertembaga Kota Bitung Provinsi Sulawesi Utara dengan tujuan (1) Untuk menganalisis peran, akses dan kotrol atas asset dan sumberdaya dan kekuatan pengambilan kepeutusan perempuan pedagang ikan (2) Untuk menganalisis peranan perempuan pedagang ikan pada rantai nilai pemasaran tuna-cakalang. Manfaat yang diharapkan dari penelitian ini yaitu: (1) Menerapkan ilmu pengetahuan yang telah diperoleh selama kuliah melalui penelitian yang dilakukan di lapangan. (2) Menambah pengetahuan sebagai bekal dalam mengaplikasikan pengetahuan teoritik terhadap masalah praktis. (3) Memberikan sumbangan yang berarti bagi pemerintah dan berbagai pihak juga sebagai bahan tambahan informasi pada yang membutuhkan.Hasil penelitian menunjukkan bahwa peranan perempuan pada rantai nilai pemasaran tuna cakalang sangat besar yaitu mulai dari membeli hingga memasarkan. Laki-laki berperan hanya pada kegiatan mengangkut ikan, baik dari atas kapal maupun ke pasar. Hasil analisis juga menunjukkan perempuan pedagang ikan memiliki peran yang lebih dalam kegiatan domestik, publik dan sosial kemasyarakatan. Perempuan pedagang ikan juga memiliki peran terhadap akses dan kontrol atas aset dan sumber daya perikanan, sedangkan untuk pengambilan keputusan mengenai USAha memasarkan ikan, hal ini sebagian besar dilakukan oleh perempuan. Laki-laki hanya berperan dalam pengambilan keputusan mengenai penetapan dan peminjaman modal
Sustainable desalination : a case of renewable energy
Paper presented at the 6th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, South Africa, 30 June - 2 July, 2008.A new energy-efficient and sustainable desalination system
has been developed in this research. This system operates under
near-vacuum conditions created by exploiting natural means of
gravity and barometric pressure head. The system can be
driven by low grade heat sources such as solar energy or waste
heat streams. Theoretical and experimental studies were
conducted to evaluate and demonstrate the feasibility of the
proposed process. Theoretical studies included thermodynamic
analysis and process modelling to evaluate the performance of
the process driven by the following alternate energy sources:
solar thermal energy, solar photovoltaic/thermal energy,
geothermal energy, and process waste heat emissions.
Experimental studies included prototype scale demonstration of
the process using direct solar and a combination of solar
photovoltaic/thermal sources. In the tests using direct solar
energy, freshwater production of 5 L/d was achieved using
direct solar energy alone, at efficiencies ranging from 65 to
75%. In the tests using solar photovoltaic/thermal energy,
freshwater production of 10 L/d was achieved, at efficiencies
ranging from 65 to 90%. Specific energy required for this
process to produce 1 kg of freshwater was 2926 kJ, all of which
was derived from solar energy.vk201
Optimized tomography methods for plasma emissivity reconstruction at the ASDEX Upgrade tokamak
Optimized tomography methods for plasma emissivity reconstruction at the ASDEX Upgrade tokamak
The soft X-ray (SXR) emission provides valuable insight into processes happening inside of high-temperature plasmas. A standard method for deriving the local emissivity profiles of the plasma from the line-of-sight integrals measured by pinhole cameras is the tomographic inversion. Such an inversion is challenging due to its ill-conditioned nature and because the reconstructed profiles depend not only on the quality of the measurements but also on the inversion algorithm used. This paper provides a detailed description of several tomography algorithms, which solve the inversion problem of Tikhonov regularization with linear computational complexity in the number of basis functions. The feasibility of combining these methods with the minimum Fisher information regularization is demonstrated, and various statistical methods for the optimal choice of the regularization parameter are investigated with emphasis on their reliability and robustness. Finally, the accuracy and the capability of the methods are demonstrated by reconstructions of experimental SXR profiles, featuring poloidal asymmetric impurity distributions as measured at the ASDEX Upgrade tokamak
Correcting Model Misspecification via Generative Adversarial Networks
Machine learning models are often misspecified in the likelihood, which leads
to a lack of robustness in the predictions. In this paper, we introduce a
framework for correcting likelihood misspecifications in several paradigm
agnostic noisy prior models and test the model's ability to remove the
misspecification. The "ABC-GAN" framework introduced is a novel generative
modeling paradigm, which combines Generative Adversarial Networks (GANs) and
Approximate Bayesian Computation (ABC). This new paradigm assists the existing
GANs by incorporating any subjective knowledge available about the modeling
process via ABC, as a regularizer, resulting in a partially interpretable model
that operates well under low data regimes. At the same time, unlike any
Bayesian analysis, the explicit knowledge need not be perfect, since the
generator in the GAN can be made arbitrarily complex. ABC-GAN eliminates the
need for summary statistics and distance metrics as the discriminator
implicitly learns them and enables simultaneous specification of multiple
generative models. The model misspecification is simulated in our experiments
by introducing noise of various biases and variances. The correction term is
learnt via the ABC-GAN, with skip connections, referred to as skipGAN. The
strength of the skip connection indicates the amount of correction needed or
how misspecified the prior model is. Based on a simple experimental setup, we
show that the ABC-GAN models not only correct the misspecification of the
prior, but also perform as well as or better than the respective priors under
noisier conditions. In this proposal, we show that ABC-GANs get the best of
both worlds
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