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Energy and Power Engineering 2022年第3期14卷 147-155页

作者： Paul Njogu francis xavier ochieng Benard Ogembo Stephen Ondimu Christopher Kanali Erick Ronoh Daniel Omondi Hiram Ndiritu Institute of Energy and Environmental Technology JKUAT Nairobi Kenya School of Biosystems and Environmental Engineering JKUAT Nairobi Kenya School of Mechanical and Manufacturing Engineering JKUAT Nairobi Kenya

Mesophilic biogas production and substrate decomposition is one of the significant limiting steps in biogas generation. The rate of generation and quality often affect the viability of biogas systems. This study assessed the potential for biogas process catalysis using powdered Sorghum bicolor L., Zea mays, and Pennisetum glaucum. The kinetics and biogas generation processes were studied. Experiments were conducted in 1 m3 tubular batch reactors, where batches were dosed with various organic biomolecules. Results show that the use of P. glaucum L. and S. bicolor L. reduced the biogas retention times significantly. Biogas generation commenced after the first day for digesters fed with S. bicolor L. and P. glaucum L. while one with Z. mays and control occurred on day two. The rate of biomethanation and methane content were enhanced. S. bicolor L. led to the highest methane content. Findings reveal that locally available organic biomolecules improved biogas quality and quantity.

关键词： Mesophilic Kinetics Biomolecules Biomethanation Reaction Rates Anaerobic

Effect of an adverse pressure gradient on the streamwise Reynolds stress profile maxima in a turbulent boundary layer

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Acta Mechanica Sinica 2013年第3期29卷 395-398页

作者： Wei Ma xavier Ottavy Li-Peng Lu francis Leboeuf Laboratoire de Mécanique des Fluides et d'Acoustique Ecole Centrale de Lyon School of Jet Propulsion Beihang University

It is widely accepted that in a turbulent boundary layer （TBL） with adverse pressure gradient （APG） an outer peak usually appears in the profile of streamwise Reynolds stress. However, the effect of APG on this outer peak is not clearly understood. In this paper, the effect of APG is analysed using the numerical and experimental results in the literature. Because the effect of upstream flow is inherent in the TBL, we first analyse this effect in TBLs with zero pressure gradient on flat plates. Under the individual effect of upstream flow, an outer peak already appears in the profile of streamwise Reynolds stress when the TBL continues developing in the streamwise direction. The APG accelerates the appearance of the outer peak, instead of being a trigger.

关键词： Turbulent boundary layer · Pressure gradient · Reynolds stress

Experimental Study of Corner Stall in a Linear Compressor Cascade

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Chinese Journal of Aeronautics 2011年第3期24卷 235-242页

作者： MA Wei OTTAVY xavier LU Lipeng LEBOEUF francis GAO Feng Laboratoire de Mecanique des Fluides et d'Acoustique Ecole Centrale de Lyon Ecully 69134 France School of Jet Propulsion Beihang University Beijing 100191 China

In order to gain a better knowledge of the mechanisms and to calibrate computational fluid dynamics （CFD） tools including both Reynolds-averaged Navier-Stokes （RANS） and large eddy simulation （LES）, a detailed and accurate experimental study of comer stall in a linear compressor cascade has been carried out. Data are taken at a Reynolds number of 382 000 based on blade chord and inlet velocity. At first, inlet flow boundary layer is surveyed using hot-wire anemometry. Then in order to investigate the effects of incidence, measurements are acquired at five incidences, including static pressures on both blade and endwall sur- faces measured by pressure taps and the total pressure losses of outlet flow measured by a five-hole pressure probe. The maxi- mum losses as well as the extent of losses of the comer stall are presented as a function of the investigated incidences.

关键词： comer separation compressor cascades incidence hot-wire anemometry computational fluid dynamics

Hazards:Maximizing Awareness,Minimizing Risks

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地学前缘 2009年第S1期16卷 110-110页

作者： francis xavier Lukwiya Uganda Martyrs University

Hazards refer to situations with harmful effects on people’s lives,property,health and the environment. Examples include:fire outbreaks,hailstorms,smoke and haze,volcanic eruptions,earthquakes,landslides, drought,floods,dust storm,global warming.Their remedies are:(1)sensitization of masses to take precaution;(2)resettlement of people based around hazardous areas;(3)instructing workers about the

关键词： hazard risk remedy example

Preliminary Investigation on Establishing a New Resilient Modulus Test Approach for Reduced Size Asphalt Mixture Samples Smaller Than 100 mm Diameter

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Journal of Traffic and Transportation Engineering 2020年第3期8卷 93-105页

作者： Ratnasamy Munaindy francis xavier Fauzan Jakarni Salihudin Hassim Department of Civil Engineering Universiti Putra MalaysiaSerdangSeri Kembangan 43400Malaysia

The performance evaluation of existing flexible pavements has become a priority issue for many highway maintenances engineers.To make appropriate rehabilitation and management decisions,the engineers most often rely on efficient methods for the determination of the strength of pavement layers.Resilient modulus is a very important parameter to be identified and used in pavement design.The resilient moduli of asphalt mixtures are typically measured using the indirect tension test procedure in compliance with the ASTM D4123 standard that is superseded by ASTM D7369.The standard requirement is that the prepared specimens for the tests should have a minimum height of the sample over its diameter ratio of 0.4.Generally,specimens used in the tests are either a nominal 100 mm or 150 mm in diameter with a minimum thickness over diameter ratio of 0.4.However,100 mm diameter core specimens taken from site wearing courses with thicknesses ranging from 40 mm to 50 mm most often do not fulfil the minimum ratio of 0.4 after they are trimmed for testing.Since there was no any option,part of the binder courses had to be trimmed to make up for the minimum ratio requirement.This tends to result in inaccurate assessment of the resilient modulus values of the samples.As such,a new procedure was explored to test specimens smaller than 100 mm in diameter.This may minimize the material volume requirement from the field and also for the fabrication of smaller samples in the laboratory.Based on the available thickness of wearing course or overlay,the appropriate sizes were determined.For a two-layer system a 56.3 mm diameter was deemed necessary while a 37.5 mm diameter was observed to be appropriate for a three-layer system.Such an approach for resilient modulus test using miniature specimens of 56.3 mm and 37.5 mm in diameter has a great potential for practical relevance for the industry.

关键词： Resilient modulus new procedure cost time and less destructive.

A Novel Text Steganography Based on Character-Alphabetic

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A Novel Text Steganography Based on Character-Alphabetic

作者： francis xavier Kofi Akotoye 湖南大学

学位级别：硕士

Modern computer networks make it possible to distribute documents quickly and economically. This is because of the decreasing cost of the equipment needed to copy, to print and to process the information. The widespread adoption of electronic distribution of copyrighted material is accompanied by illicit copying and illicit distribution. This is why individuals, businesses and governments have come to think of how to protect their work, how to prevent such illicit activities and how to trace the distribution of a document. It is in this context that a lot of attention is being focused on steganography. Steganography is a technique that allows users to hide a message in another message so that an eavesdropper cannot even tell that a secret message is being sent. Although steganography has been with mankind since 5th century BC, the scientific study of steganography did not begin until just recently when Simmons broached the topic in his 1983 publication“Prisoner’s Problem”. Digital steganography is based on two principles of altering digitized information to a certain extent while retaining its original functionality, and also to ensure that minute changes to marked documents are indistinguishable to humans. Using steganography and digital watermarks it is possible to hide copyright information, such as the ID of the author, the date of creation, and any other piece of information necessary inside a digital document.Implementing steganography in text document is not an easy undertaking considering the fact that text document has very few places in which to embed hidden data. Any minute change introduce to text objects can easily be noticed thus attracting attention from possible hackers. Though a lot of schemes have been proposed which to a large extent maintains the economic and aesthetic value of the document after embedding, most of these schemes do not boast of large embedding capacities. This project investigates the possibility of embedding data in text document by manipulating the alphabetic order

关键词： embedding hidden artifacts bounding secret watermark hiding robustness instance looking

On the Monotonicity of (κ; g, h)-graphs

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Acta Mathematicae Applicatae Sinica 2002年第3期18卷 477-480页

作者： Bao-guang Xu, Ping Wang, Jian-fang WangInstitute of Policy and Management, Chinese Academy of Sciences, Beijing 100080, ChinaDepartment of Mathematics, Statistics and Computer Science, St. francis xavier University, Antigonish, NS, Canada, B2G 2W5Institute of Applied Mathematics, Academy of Mathematics and System Sciences, Chinese Academy of Sciences, Beijing, 100080, China

A (k;g)-graph is a k-regular graph with girth g. A (k;g)-cage is a (k;g)-graph with the least possible number of vertices. Let f(k;g) denote the number of vertices in a (k;g)-cage. The girth pair of a graph gives the length of a shortest odd and a shortest even cycle. A fc-regular graph with girth pair (g,h) is called a (k;g,h)-graph. A (k;g,h)-cage is a (k;g,h)-graph with the least possible number of vertices. Let f(k;g,h) denote the number of vertices in a (k;g,h)-cage. In this paper, we prove the following strict inequality f(k;h-1,h)

关键词： Cages graph girth pair regular graph

On the relations among best approximation and Fourier coeffcients

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Science China Mathematics 2008年第10期51卷 1883-1894页

作者： YU DanSheng1,2, ZHOU Ping2 & ZHOU SongPing1 1 Institute of Mathematics, Zhejiang Sci-Tech University, Hangzhou 310018, China 2 Department of Mathematics, Statistics and Computer Science, St. francis xavier University, Antigonish, Nova Scotia, Canada, B2G 2W5

We discuss the relations among the best approximation En(f) and the Fourier coeffcients of a function, f(n) ∈ C,n = 0,±1,±2,..., under the conditions that {f (n)}∞n=0 ∈ MVBVS* and {f (n) + f(n)}∞n=0 ∈ MVBVS*, w... 详细信息

关键词： best approximation Fourier coeffcients mean value bounded variation

An Application of Hypergraph on the Generalized Gossip Problem

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An Application of Hypergraph on the Generalized Gossip Probl...