2,756 research outputs found
Coupled Vlasov and two-fluid codes on GPUs
We present a way to combine Vlasov and two-fluid codes for the simulation of
a collisionless plasma in large domains while keeping full information of the
velocity distribution in localized areas of interest. This is made possible by
solving the full Vlasov equation in one region while the remaining area is
treated by a 5-moment two-fluid code. In such a treatment, the main challenge
of coupling kinetic and fluid descriptions is the interchange of physically
correct boundary conditions between the different plasma models. In contrast to
other treatments, we do not rely on any specific form of the distribution
function, e.g. a Maxwellian type. Instead, we combine an extrapolation of the
distribution function and a correction of the moments based on the fluid data.
Thus, throughout the simulation both codes provide the necessary boundary
conditions for each other. A speed-up factor of around 20 is achieved by using
GPUs for the computationally expensive solution of the Vlasov equation and an
overall factor of at least 60 using the coupling strategy combined with the GPU
computation. The coupled codes were then tested on the GEM reconnection
challenge
Molecular Hydrogen and Paschen-alpha Emission in Cooling Flow Galaxies
We present near-infrared spectra obtained to search for Pa-alpha and
molecular hydrogen lines in edge-darkened (FR I-type) radio galaxies with
bright Halpha emission in the redshift range 0.0535<z<0.15. We find that all
three galaxies in our sample (PKS 0745-191, PKS 1346+26, & PKS2322-12) which
are associated with strong cooling flows also have strong Pa-alpha and H_2
(1-0) S(1) through S(5) emission, while other radio galaxies do not. Together
with earlier observations this confirms claims that cooling flow galaxies are
copious emitters of molecular hydrogen with large H_2 (1-0) S(3)/Pa-alpha
ratios in the range 0.5 to 2. The emission is centrally concentrated within the
inner few kiloparsec and could come from warm (T ~ 1000-1500 K) molecular
material which is being deposited by the cooling flow. We speculate that the
H_2 emission could be related to the interaction between the jets and this
molecular gas.Comment: ApJ Letters, in press, AAS LaTex, preprint also available at
http://www.astro.umd.edu/~hfalcke/publications.html#nirga
Penerapan Good Corporate Governance dan Earning Management terhadap Biaya Hutang pada Perusahaan BUMN Listing CGPI 2010 – 2012
The company's efforts in increasing the high trust of creditors will be low risk, so the company can improve the effectiveness of motoring action that is in company like Good Corporate Governance. Investors tend to see the level of GCG implementation as an indicator of the company's risk level before making a funding decision. While the decision of investors in investing in a company based on various considerations, one of which is profit. As an organization, BUMN functioning as a development agent but also carrying out government policies and programs, while on the other hand it is required to become a healthy business unit. The results of this study indicate that the GCG index has no significant effect on the cost of debt and accrual income management has a significant effect on the cost of debt. It means that earnings management is done by management to influence investor perception, especially to influence buying decision of company stock and influence company value
Concurrent Segmentation and Localization for Tracking of Surgical Instruments
Real-time instrument tracking is a crucial requirement for various
computer-assisted interventions. In order to overcome problems such as specular
reflections and motion blur, we propose a novel method that takes advantage of
the interdependency between localization and segmentation of the surgical tool.
In particular, we reformulate the 2D instrument pose estimation as heatmap
regression and thereby enable a concurrent, robust and near real-time
regression of both tasks via deep learning. As demonstrated by our experimental
results, this modeling leads to a significantly improved performance than
directly regressing the tool position and allows our method to outperform the
state of the art on a Retinal Microsurgery benchmark and the MICCAI EndoVis
Challenge 2015.Comment: I. Laina and N. Rieke contributed equally to this work. Accepted to
MICCAI 201
Analisis Strategi Bersaing pada Distributor Gula di Indonesia
Penelitian ini dilakukan dengan tujuan untuk mengetahui strategi bersaing yang dapat digunakan dalam menghadapi persaingan di sektor perdagangan industri distributor gula. Seperti yang kita ketahui bahwa produksi gula di Indonesia, sampai saat ini masih belum dapat memenuhi permintaan masyarakat Indonesia. Oleh karena itu pemerintah tidak punya pilihan lain selain mengimport gula dari luar negeri untuk dapat memenuhi permintaan gula di pasar. Hal ini menyebabkan banyak pembisnis yang berkecimpung dalam bisnis ini, hal ini menjadi sangat menarik untuk diteliti bagi penulis mengenai bagaimana strategi yang dapat digunakan Perusahaan distributor gula untuk dapat bersaing dengan Perusahaan pesaing yang ada. Pengumpulan data dilakukan oleh penulis dengan cara wawancara dan observasi secara langsung di lapangan. Setelah mendapatkan data, penulis memastikan keabsahan data dengan metode Trianggulasi. Cara yang dilakukan dalam penelitian ini adalah dengan membadingkan data hasil pengamatan dengan data hasil wawancara, dan membandingkannya kembali dengan data – data tertulis yang dimiliki oleh Perusahaan . Hasil penelitian ini menunjukan, bahwa strategi yang digunakan oleh Perusahaan adalah pengembangan pasar, dan strategi ini masih relevan untuk digunakan. Perusahaan hanya perlu menambahkan strategi baru yaitu penetrasi pasar untuk dapat memaksimalkan omset penjualan
Real-time 3D Tracking of Articulated Tools for Robotic Surgery
In robotic surgery, tool tracking is important for providing safe tool-tissue
interaction and facilitating surgical skills assessment. Despite recent
advances in tool tracking, existing approaches are faced with major
difficulties in real-time tracking of articulated tools. Most algorithms are
tailored for offline processing with pre-recorded videos. In this paper, we
propose a real-time 3D tracking method for articulated tools in robotic
surgery. The proposed method is based on the CAD model of the tools as well as
robot kinematics to generate online part-based templates for efficient 2D
matching and 3D pose estimation. A robust verification approach is incorporated
to reject outliers in 2D detections, which is then followed by fusing inliers
with robot kinematic readings for 3D pose estimation of the tool. The proposed
method has been validated with phantom data, as well as ex vivo and in vivo
experiments. The results derived clearly demonstrate the performance advantage
of the proposed method when compared to the state-of-the-art.Comment: This paper was presented in MICCAI 2016 conference, and a DOI was
linked to the publisher's versio
Pengembangan Modul Luas dan Keliling Bangun Datar yang Valid dengan Pendekatan Kontekstual Berbasis Keunggulan Lokal di Sekolah Dasar
Penelitian ini bertujuan untuk menghasilkan modul luas dan keliling bangun datar yang valid di sekolah dasar. Jenis penelitian ini adalah penelitian pengembangan dengan menggunakan model 4D (define, design, develop, dan desseminate). Tahap desseminate tidak dilakukan. Penelitian ini untuk mengetahui apakah modul yang dirancang sudah valid, kemudian divalidasi oleh pakar mengenai materi, penyajian, bahasa dan keterbacaan. Hasil penelitian menunjukkan bahwa modul luas dan keliling bangun datar sudah valid oleh pakar. Oleh sebab itu, disimpulkan bahwa modul luas dan keliling bangun datar di sekolah dasar telah valid
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