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

Marketing Strategies of Indigenous Companies in the Nigeria Environment

The study investigated how indigenous companies operating within the turbulent Nigerian marketing environment utilized the mixes of different marketing strategies at different periods of products' supply situations for their economic growth and development, and how these strategies were effectively managed in the acquisition of market shares within the food and beverage industry. Theoretical models were used in developing the only hypothesis that was investigated through the survey of one-hundred and twenty indigenous companies which were· randomly selected. With four copies of the questionnaire administered to each of the 120 companies, additional 20 copies were added to round up 500 copies administered to respondents in the companies. The findings revealed that Nigerian indigenous companies were unable to effectively use different marketing strategies at periods of products' supply situations; also they could not effectively use marketing strategies to acquire the desired market share within the industry in the last five years. The conclusion drawn from the findings was that Nigerian indigenous companies exhibited low skill in the adoption and mixes of marketing strategies. It was recommended that Nigerian indigenous companies should take advantage of the knowledge of their environment and people, and adopt marketing strategies, while academics, consultants, professionals and relevant government agencies need to train the operators of indigenous companie

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 Bi2_2Se3_3 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 Bi$_2$Se$_3$ 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