4,054 research outputs found
Towards the Formal Reliability Analysis of Oil and Gas Pipelines
It is customary to assess the reliability of underground oil and gas
pipelines in the presence of excessive loading and corrosion effects to ensure
a leak-free transport of hazardous materials. The main idea behind this
reliability analysis is to model the given pipeline system as a Reliability
Block Diagram (RBD) of segments such that the reliability of an individual
pipeline segment can be represented by a random variable. Traditionally,
computer simulation is used to perform this reliability analysis but it
provides approximate results and requires an enormous amount of CPU time for
attaining reasonable estimates. Due to its approximate nature, simulation is
not very suitable for analyzing safety-critical systems like oil and gas
pipelines, where even minor analysis flaws may result in catastrophic
consequences. As an accurate alternative, we propose to use a
higher-order-logic theorem prover (HOL) for the reliability analysis of
pipelines. As a first step towards this idea, this paper provides a
higher-order-logic formalization of reliability and the series RBD using the
HOL theorem prover. For illustration, we present the formal analysis of a
simple pipeline that can be modeled as a series RBD of segments with
exponentially distributed failure times.Comment: 15 page
Multicriterial ranking approach for evaluating bank branch performance
14 ranking methods based on multiple criteria are suggested for evaluating the performance of the bank branches. The methods are explained via an illustrative example, and some of them are applied to a real-life data for 23 retail bank branches in a large-scale private Turkish commercial bank
Pemodelan Dan Simulasi Penyebaran Penyakit Demam Berdarah Dengue (DBD) Dengan Menggunakan Model Cellular Automata
Demam Berdarah Dengue (DBD) merupakan salah satu masalah kesehatan masyarakat di Indonesia. Penyakit demam berdarah sering terjadi di daerah tropis dikarenakan nyamuk pembawa virus terdapat hampir di seluruh pelosok Indonesia khususnya daerah yang beriklim tropis. Kota Manado merupakan salah satu daerah yang endemik untuk kasus demam berdarah, jumlah kasus DBD di kota Manado hampir setiap tahunnya meningkat. Melihat realita kasus DBD yang terjadi, maka perlu adanya kerja sama dari semua elemen baik dari masyarakat umum, pelayanan kesehatan, dunia pendidikan dan pemerintah untuk bersama-sama mencegah terjadinya wabah demam berdarah dilingkungan sekitar tempat tinggal. Penelitian ini akan membahas tentang perkembangan penyakit DBD i kota Manado pada tahun 2011 – 2014, sehingga dari hasil penelitian tersebut menghasilkan sebuah aplikasi yang dapat menjalankan simulasi penyebaran penyakit DBD pada tahun 2011 – 2014 di kota Manado. Aplikasi tersebut bermanfaat untuk memberikan informasi tentang perkembangan kasus DBD tahun 2011 – 2014 pada 9 kecamatan yang ada di kota Manado
Estimation of noise in gray-scale and colored images using median absolute deviation (MAD)
This paper presents a new algorithm for estimation of noise (i.e., level of noise) in both gray-scale and color images (GSI, CI). The new technique is called median-absolute deviation (MAD). This technique does require an explicit estimation of the noise level or the signal to noise ratio (SNR), which is usually needed in most of the popular enhancement methods. Performance of the proposed method is evaluated on noisy images in real conditions and with artificial noise
Extracorporeal shock wave lithotripsy (ESWL) versus flexible ureteroscopy (F-URS) for management of renal stone burden less than 2 cm in children: A randomized comparative study
Objective: To compare the outcome of flexible ureteroscopy (F-URS) versus extracorporeal shock wave lithotripsy (ESWL) for the management of renal stone burden less than 2 cm in children.Patients and methods: A randomized comparative study was conducted at our hospital between December 2013 and May 2015. Seventy two children with renal stone burden less than 2 cm were assessed for eligibility. Our primary outcome is to assess the stone free rate after the first session. The secondary goal is to assess the operative outcome and the associated postoperative complications.Results: Finally, 57 children were completed the treatment and follow up; 27 patients in F-URS group and 30 patients in ESWL group. Patient’s demographics and stone characteristics were comparable between both groups. F-URS group was associated with significantly longer operative time and hospital stay versus ESWL group. Overall complications occurred in 29.6% and 33.3% in F-URS groups and ESWL group, respectively (p value = 0.1) and most of them were of minor degree. F-URS was associated with significantly higher stone free rate after the first session which reached 81.4% versus 53.3% for ESWL group (p value = 0.00). The overall success was 92.5% and 90% in F-URS and ESWL group, respectively (p value = 0.5).Conclusion: Stone free rate after one session of F-URS is higher than ESWL with comparable rates of complications. F-URS could be offered to children who are less likely to respond completely after ESWL monotherapy.Keywords: Pediatric urolithiasis; Minimal invasive stone management; Flexible URS; ESW
Challenges in Bridging Social Semantics and Formal Semantics on the Web
This paper describes several results of Wimmics, a research lab which names
stands for: web-instrumented man-machine interactions, communities, and
semantics. The approaches introduced here rely on graph-oriented knowledge
representation, reasoning and operationalization to model and support actors,
actions and interactions in web-based epistemic communities. The re-search
results are applied to support and foster interactions in online communities
and manage their resources
Photoemission of BiSe with Circularly Polarized Light: Probe of Spin Polarization or Means for Spin Manipulation?
Topological insulators are characterized by Dirac cone surface states with
electron spins aligned in the surface plane and perpendicular to their momenta.
Recent theoretical and experimental work implied that this specific spin
texture should enable control of photoelectron spins by circularly polarized
light. However, these reports questioned the so far accepted interpretation of
spin-resolved photoelectron spectroscopy. We solve this puzzle and show that
vacuum ultraviolet photons (50-70 eV) with linear or circular polarization
probe indeed the initial state spin texture of BiSe while circularly
polarized 6 eV low energy photons flip the electron spins out of plane and
reverse their spin polarization. Our photoemission calculations, considering
the interplay between the varying probing depth, dipole selection rules and
spin-dependent scattering effects involving initial and final states explain
these findings, and reveal proper conditions for light-induced spin
manipulation. This paves the way for future applications of topological
insulators in opto-spintronic devices.Comment: Submitted for publication (2013
Formal Analysis of Linear Control Systems using Theorem Proving
Control systems are an integral part of almost every engineering and physical
system and thus their accurate analysis is of utmost importance. Traditionally,
control systems are analyzed using paper-and-pencil proof and computer
simulation methods, however, both of these methods cannot provide accurate
analysis due to their inherent limitations. Model checking has been widely used
to analyze control systems but the continuous nature of their environment and
physical components cannot be truly captured by a state-transition system in
this technique. To overcome these limitations, we propose to use
higher-order-logic theorem proving for analyzing linear control systems based
on a formalized theory of the Laplace transform method. For this purpose, we
have formalized the foundations of linear control system analysis in
higher-order logic so that a linear control system can be readily modeled and
analyzed. The paper presents a new formalization of the Laplace transform and
the formal verification of its properties that are frequently used in the
transfer function based analysis to judge the frequency response, gain margin
and phase margin, and stability of a linear control system. We also formalize
the active realizations of various controllers, like
Proportional-Integral-Derivative (PID), Proportional-Integral (PI),
Proportional-Derivative (PD), and various active and passive compensators, like
lead, lag and lag-lead. For illustration, we present a formal analysis of an
unmanned free-swimming submersible vehicle using the HOL Light theorem prover.Comment: International Conference on Formal Engineering Method
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