4,831 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
Ballisticity of nanotube FETs: Role of phonon energy and gate bias
We investigate the role of electron-phonon scattering and gate bias in
degrading the drive current of nanotube MOSFETs. Our central results are: (i)
Optical phonon scattering significantly decreases the drive current only when
gate voltage is higher than a well-defined threshold. It means that elastic
scattering mechanisms are most detrimental to nanotube MOSFETs. (ii) For
comparable mean free paths, a lower phonon energy leads to a larger degradation
of drive current. Thus for semiconducting nanowire FETs, the drive current will
be more sensitive than carbon nanotube FETs because of the smaller phonon
energies in semiconductors. (iii) Radial breathing mode phonons cause an
appreciable reduction in drive current.Comment: 16 pages, 1 table, 4 figure
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
An in-depth look at prior art in fast round-robin arbiter circuits
Arbiters are found where shared resources exist such as busses, switching fabrics, processing elements. Round-robin is a fair arbitration method, where requestors get near-equal shares of a common resource or service. Round-robin arbitration (RRA) finds use in network switches/routers and processor boards/systems as well as many other applications that have concurrency. Today's electronic systems require arbiters with hundreds of ports (e.g., switching fabrics with virtual I/O queues) and clock speeds near the limits of even the latest microelectronics fabrication processes/libraries. Achieving high clock speeds in the presence of large number of ports is only possible with highly parallel arbiter architectures. This paper presents an in-depth literature survey of previous work on this problem. It looks at RRA work in the literature in a bigger context, then defines the typical RRA problem (RRA_typical), and specifically investigates work on fast architectures that solve the RRA_typical problem. There are five such works that are really competitive. This report takes a very in-depth look at these works. It explains each architecture and how/why it works from a unique perspective that cannot be found in the original publication of that architecture. It also proposes improvements to these architectures. We wrote generators for the improved versions of these architectures. We will share a summary of synthesis results in this report – although a detailed account of how these results were obtained and their analysis is the subject of another (upcoming) publicatio
A Novel Real-Time Non-invasive Hemoglobin Level Detection Using Video Images from Smartphone Camera
Hemoglobin level detection is necessary for evaluating health condition in the human. In the laboratory setting, it is detected by shining light through a small volume of blood and using a colorimetric electronic particle counting algorithm. This invasive process requires time, blood specimens, laboratory equipment, and facilities. There are also many studies on non-invasive hemoglobin level detection. Existing solutions are expensive and require buying additional devices. In this paper, we present a smartphone-based non-invasive hemoglobin detection method. It uses the video images collected from the fingertip of a person. We hypothesized that there is a significant relation between the fingertip mini-video images and the hemoglobin level by laboratory gold standard. We also discussed other non-invasive methods and compared with our model. Finally, we described our findings and discussed future works
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