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Evaluation of fiber optic methane sensor using a smoke chamber

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International Journal of Mining Science and Technology 2018年第6期28卷 969-974页

作者： Mingming Li Thomas Dubaniewicz Heather Dougherty Jim addis National Institute for Occupational Safety and Health Pittsburgh Mining Research Division

This report presents the results of experiments to evaluate a prototype fiber optic methane monitor exposed to smoke using a smoke chamber to simulate atmospheric conditions in an underground coal mine after a fire or explosion. The experiments were conducted using test fires of different combustible sources commonly found in mines —douglas-fir wood, SBR belt, and Pittsburgh seam coal. The experiments were designed to assess the response of the fiber optic methane sensor to different contaminants,different contaminant levels and different contaminant durations produced from the test fires. Since the prototype methane monitor detects methane by measuring absorption at a specific wavelength, optical power at the absorption wavelength(1650 nm) was measured as a function of smoke concentration and duration. The other sensor response parameter-methane response times-were measured between smoke tests to assess the impact of soot accumulation on the sensor. Results indicate that the sensor screen effectively prevented smoke from obscuring the optical beam within the sensor head, with minimal impact on the system optical power budget. Methane response times increased with smoke exposure duration, attributed to soot loading on the protective screen.

关键词： Fiber optic Methane sensor Fires Optical power Response time

Closed-form solution for shock wave propagation in density-graded cellular material under impact

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Theoretical & Applied Mechanics Letters 2021年第5期11卷 252-259页

作者： Vijendra Gupta addis Kidane Michael Sutton Department of Mechanical Engineering University of South Carolina300 Main StreetColumbiaSC 29208USA

Density-graded cellular materials have tremendous potential in structural applications where impact resistance is *** materials subjected to high impact loading result in a compaction type deformation,usually modeled using continuum-based shock *** resulting governing differential equation of the shock model is nonlinear,and the density gradient further complicates the *** studies have employed numerical methods to obtain the *** this study,an analytical closed-form solution is proposed to predict the response of density-graded cellular materials subjected to a rigid body *** for the velocity of the impinging rigid body mass,energy absorption capacity of the cellular material,and the incident stress are obtained for a single shock *** results obtained are in excellent agreement with the existing numerical solutions found in the *** proposed analytical solution can be potentially used for parametric studies and for effectively designing graded structures to mitigate impact.

关键词： Functionally graded cellular material Analytical modeling Impact response Closed-form solution Energy absorption Density gradient

Predicting the spatial distribution of soil erodibility factor using USLE nomograph in an agricultural watershed,Ethiopia

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International Soil and Water Conservation Research 2015年第4期3卷 282-290页

作者： Hailu Kendie addis Andreas Klik Institute of Hydraulics and Rural Water Management University of Natural Resources and Life SciencesViennaAustria Gondar Agricultural Research Center Soil and Water Management DirectorateGondarEthiopia

Soil erosion in the northwestern Amhara region,Ethiopia has been a subject of anxiety,resulting in a major environmental threat to the sustainability and productive capacity of agricultural *** study tried to estimate soil erodibility factor(Kfactor)using Universal Soil Loss Equation(USLE)nomograph,and evaluate the spatial distribution of the predicted K-factor in a mountainous agricultural *** investigate the K-factor,the 54 km2 study watershed was divided into a 500 m by 500 m square grid and approximately at the center of each grid,topsoil samples(roughly 10 to 20 cm depth)were collected over 234 ***,silt,clay and organic matter(OM)percentage were analyzed,while soil permeability and structure class codes were obtained using the United States Department of Agriculture(USDA)*** resulting coefficient of variation(CV)of the estimated K-factor was 0.31,suggesting a moderate ***,the value of nugget to sill ratio of K-factor was 0.32,which categorized as moderate spatial *** accuracy and model fitting effect of the Gaussian semivariogram approach was best,suggesting that the Gaussian ordinary Kriging model was more appropriate for predicting *** resulting value of the mean error(ME)was 0 and the mean squared deviation ratio(MSDR)was nearly 1,which indicates the Gaussian model was unbiased and reproduced the experimental variance *** values of K-factor were smaller(0.0217 to 0.0188)in the northern part and gradually increased(0.0273 to 0.033 Mg h MJ^(-1)mm^(-1))towards the central and south of the study watershed.

关键词： Nomograph Semivariogram Soil erodibility factor Spatial variability Watershed

Active trachoma prevalence and its associated factors among children aged 1-9 years in rural residents of Lare District, Southwest Ethiopia

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International Journal of Ophthalmology(English edition) 2021年第11期14卷 1756-1764页

作者： Yitayeh Belsti Sofonias addis Fekadu Abel Sinshaw Assem Department of Physiology College of Medicine and Health SciencesUniversity of GondarGondar 196Ethiopia Department of Optometry College of Medicine and Health SciencesUniversity of GondarGondar 196Ethiopia

AIM:To determine the prevalence of active trachoma and its associated factors among children in Lare District,Southwest Ethiopia,***:A community-based cross-sectional study was conducted.A total of 620 participants were recruited using a multi-stage sampling technique.A structured questionnaire,torch,and magnifying loupes were used for data *** data was entered into epidemiological information and exported to statistical package for social science version 20 for *** bi-variable and multivariable Logistic regression analysis model was fitted to identify factors associated with active *** ratio with a 95%CI was used to show the direction and strength of association between independent and outcome ***:A total of 610 children participated in this study with a response rate of 98.39%.The prevalence of active trachoma was 132(21.60%;95%CI:18.40-24.70).Family size being 6-9(AOR=2.34;95%CI:1.14-5.02),presence of more than two preschool children in a house(AOR=2.04;95%CI:1.12-3.70),open field waste disposal system(AOR=2.62;95%CI:1.00-6.80)and type of latrine being uncovered(AOR=4.12;95%CI:2.00-8.51)were positively associated with active *** the other side,water consumption being 40-60 liters per day was a protective factor for active ***:The prevalence of active trachoma is high among children aged 1-9 y in Lare *** latrine,open field waste disposal system,family sizes of 6-9,and the presence of more than two preschool children in a house are associated with the occurrence of active *** the other side,water consumption of 40-60 liters is a protective factor.

关键词： active trachoma children Lare District Gambella Regional State Ethiopia

Harnessing the potential of additive manufacturing technologies:Challenges and opportunities for entrepreneurial strategies

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International Journal of Innovation Studies 2018年第4期2卷 123-136页

作者： Marie Lavoie James L.addis York University/Glendon College-Economics Department and Glendon School of Public and International Affairs 2275 Bayview AvenueTorontoOntarioM4N3M6Canada York University/Glendon College-Economics Department 2275 Bayview AvenueTorontoOntarioM4N3M6Canada

Additive manufacturing(AM),a revolutionary production technique that will make many previously inconceivable innovations a reality,is transforming the manufacturing *** technologies behind AM have a generic character and possess immense and transformative potential that will be felt across different sectors of the *** paper studies how entrepreneurs can access,exploit,and diffuse this new disruptive knowledge,as well as the potential challenges that lie ***,we examine the magnitude of the knowledge pool created by the Top 10 countries in AM research from 2011 to 2016;specifically,we determine the leading countries,the pattern of organizational and international collaborations,leading disciplines contributing to AM,and the pattern in authors'*** find that the US is clearly the dominant country,while China witnessed a notable acceleration in AM research between 2014 and 2016;we also show that universities are the predominant actor in codified AM knowledge *** this information,we paint a vivid picture of the technological and market opportunities for entrepreneurs and identify the gaps in the current knowledge production environment;we find that the challenges currently faced by entrepreneurs could be overcome through academic entrepreneurship,collective entrepreneurship,and the actions of an entrepreneurial state.

关键词： Additive manufacturing Knowledge pool Entrepreneurship Innovation systems Innovation policy Evolutionary economics

Microbiological characterization of a rearing system for the common sea urchin Paracentrotus lividus:a support to technical production regulations redaction and system monitoring

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Food Quality and Safety 2024年第3期8卷 603-610页

作者： Sara Maria Pani Valentina Coroneo Viviana Pasquini Adriana Sanna Piero addis Department of Medical Sciences and Public Health University of CagliariMonserratoItaly Department of Life and Environmental Science University of CagliariCagliariItaly

Objective:The overexploitation of the sea urchin Paracentrotus lividus stock,as a consequence of the growing market demand for roe,has boosted the research for echinoderm *** chemical,physical,and microbiological characteristics of land-based facilities are crucial for sea urchins’health and human consumption of their *** Italy,health-hygienic regulations for *** rearing are still to be perfected by the *** this context,we characterized the microbiological quality of a pilot land-based facility for sea urchin production at the University of Cagliari(Italy)to support the development of technical production *** and Methods:The accredited Hygiene Laboratory of Cagliari University collected and analyzed the samples in June *** bacteria,yeasts,and molds were searched for in air and on *** coliforms and Escherichia coli,Enterococci,Pseudomonadaceae,Staphylococcus aureus,sulfite-reducing Clostridia,and Vibrio *** identified in water *** searched forVibrio *** Pseudomonas *** the gonads and coelomic fluid of sea ***:Although air,surfaces,and water quality were satisfactory overall,some critical points should be monitored more *** concentration was 250 CFU/100 mL in the water reserve,suggesting animal contamination(other than humans).Pseudomonas aeruginosa was the most resistant to filtration processes,with a residual concentration of 6 CFU/250 mL after the second *** colonies of Vibrio *** Pseudomonas *** isolated in sea urchins’gonads or coelomic ***:Starting from the results,we provided targeted advice for developing technical production regulations,system monitoring,and facility routine maintenance in accordance with the‘best practice’*** analysis could be considered a first step toward the elaboration of common regulations about the minimal standards for the breeding environment of *** by national and r

关键词： Paracentrotus lividus echinoculture health hazards microbial contaminants production disciplinary Sardinia

The impacts of rice cultivation on an indigenous Fogera cattle population at the eastern shore of Lake Tana, Ethiopia

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Ecological Processes 2019年第1期8卷 252-266页

作者： Mare addis Desta Gete Zeleke William A.Payne Teshome Shenkoru Yihun Dile Department of Geography and Environmental Studies Wollo UniversityP.O.Box 1145DessieEthiopia Water and Land Management Resource Center and NCCR-RP12 Landscape Transformation Research Project in Ethiopia Addis AbabaEthiopia College of Agriculture Biotechnology and Natural ResourcesUniversity of NevadaDean’s Office/222RenoNevada 89557-0222USA Department of Agriculture Nutrition and Veterinary SciencesUniversity of NevadaMail Stop 2021664 NVirginia StreetMax Fleischmann AgricultureOffice 1125RenoNevada 89557USA Department of Ecosystem Science and Management Texas A&M UniversityCollege StationUSA.

Background:Even though increasing population pressure and associated increased demand for food and economic development have led to overexploitation and degradation of wetlands throughout the world,the drivers are most severe in developing *** generations,Fogera wetlands in Ethiopia which are parts of Lake Tana Biosphere Reserve have been widely used for grazing of indigenous *** cattle are one of several recognized indigenous breeds of Abyssinian zebu bovine cattle(Bos primigenius indicus)found in Fogera district,*** study was conducted to quantify impacts of rice expansion on cattle population in Fogera *** were collected through questionnaire,focus group discussions,interviews,and land use/land cover *** were selected using systematic random *** and LEVENES test were used to analyze the livestock unit and to check ***:The study revealed that during the 20-year period preceding 2015,the number of cattle owned decreased from 3509 to 1510 *** the same period,rice cultivation increased from 182 to 9499 ha and production from 6701 to 714,013 *** lands were reduced from 8550 to 3501 ha,wetlands from 3114 to 1060 ha,and forests from 1542 to 907 *** use/land cover changes showed a negative balance of 40%dry matter requiring cattle feed to be increasingly supplemented through purchases,or reduction in herd *** study also indicated that the land-use changes brought at the expense of traditional cattle production ***:Hence,proper management is required to maintain these valuable resources and keep their role in socioeconomic development of the area.

关键词： Indigenous cattle Wetland Agriculture Rice Grazing land Ethiopia

Opportunistic and other intestinal parasites among HIV/AIDS patients attending Gambi higher clinic in Bahir Dar city,North West Ethiopia

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Asian Pacific Journal of Tropical Medicine 2011年第8期4卷 661-665页

作者： Abebe Alemu Yitayal Shiferaw Gebeyaw Getnet Aregaw Yalew Zelalem addis Department of Medical Laboratory Sciences College of Medicine and Health SciencesUniversity of GondarGondarEthiopia

Objective:To determine the magnitude of opportunistic and non-opportunistic intestinal parasitic infections among HTV/AIDS patients in Bahir ***:Cross-sectional study was conducted among HIV/ AIDS patients attending Gambi higher clinic from Aprill- May 30,2009. Convenient sampling technique was employed to identify the study subjects and hence a total of 248 subjects were included.A pre-tested structured questionnaire was used to collect sociodemographic data of *** samples were examined by direct saline,iodine wet mount, formol-ether sedimentation concentration and modified Ziehl-Neelsen staining technique. Results:Out of 248 enrolled in the study,171(69.0%)(90 males and 81 females) were infected with one or more intestinal *** highest rate of intestinal parasites were observed among HIV/AIDS patients(80.3%,151/188),and the infection rate of HIV negative individuals was 33.3%(20/60).Cryptosporidum parvum(43.6%),Isospora belli(15.5%) and Blastocystis hominis (10.5%) were opportunistic parasites that were found only in HIV/AIDS ***: Opportunistic parasite infections are common health problem among HIV/ AIDS patients in the study ***,early detection and treatment of these parasites are important to improve the quality of life of HIV/AIDS patients.

关键词： Opportunistic parasites Non-opportunistic parasites HIV/AIDS Ethiopia

Modeling streamflow and sediment using SWAT in Ethiopian Highlands

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International Journal of Agricultural and Biological Engineering 2016年第5期9卷 51-66页

作者： Hailu Kendie addis Stefan Strohmeier Feras Ziadat Nigus Demelash Melaku Andreas Klik Institute of Hydraulics and Rural Water Management University of Natural Resources and Life SciencesVienna 1190Austria Gondar Agricultural Research Center GondarEthiopia International Center for Agricultural Research in the Dry Areas Amman 11110-17198Jordan Food and Agricultural Organization of the United Nations Rome 00100Italy

The coincidence of intensive rainfall events at the beginning of the rainy season and unprotected soil conditions after extreme dry spells expose the Ethiopian Highlands to severe soil *** and water conservation measures(SWC)have been applied to counteract land degradation in the endangered areas,but SWC efficiency may vary related to the heterogeneity of the *** Soil and Water Assessment Tool(SWAT)model was used to model hydrology and sediment dynamics of a 53.7 km^(2)watershed,located in the Lake Tana basin,*** distributed stone bund impacts were applied in the model through modification of the surface runoff ratio and adjustment of a support practice factor simulating the trapped amounts of water and sediment at the SWC structure and watershed *** resulting Nash-Sutcliffe efficiency(NSE)for daily streamflow simulation was 0.56 for the calibration and 0.48 for the validation period,suggesting satisfactory model *** contrast,the daily sediment simulation resulted in unsatisfactory model performance,with the NSE value of 0.07 for the calibration and–1.76 for the validation period and this could be as a result of high intensity and short duration rainfall events in the ***,insufficient sediment yield prediction may result to some extent from daily based data processing,whereas the driving runoff events and thus sediment loads occur on sub-daily time scales,probably linked with abrupt gully breaks and *** calibrated model indicated 21.08 Mg/hm^(2)average annual sediment yield,which is far beyond potential soil regeneration *** the given limits of model calibration,SWAT may support the scaling up and out of experimentally proven SWC interventions to encourage sustainable agriculture in the Ethiopian Highlands.

关键词： SWAT streamflow sediment dynamics soil erosion soil and water conservation watershed hydrology