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Demography and dynamics of mountain nyala Tragelaphus buxtoni in the Bale Mountains National Park,Ethiopia

Current Zoology 2010年第6期56卷 660-669页

作者： Yosef mamo Michelle A.PINARD Afework BEKELE Hawassa university Department of Wildlife and Eco-tourism university of Aberdeen Institute of Biological and Environmental Sciences Addis Ababa university Department of Biology

We studied the population dynamics of endangered mountain nyala Tragelaphus buxtoni between 2003-2005 in the Bale Mountains National Park. Line-transect sampling and total count methods were used to gather data on demographics and movement patterns. The population＇s age-group composition was 58% adults, 25% sub-adults, 9% juveniles, 5% calves and 3% unidentified with a female-male sex ratio of 2：1. Population density was found to be significantly different between the two sub-populations （Dinsho Sanctuary and Gaysay/Adelay）. A significant difference was found for age-group composition across the two sub-populations except adult females, sub-adult males and calves. The Dinsho sub-population was an isolated group. Separation and containment of the mountain nyala population could have negatively affected their ability to search for habitat requirements and mates from distant areas. The population varied between 830-908 individuals （95% CI）, a reduction of 45% from earlier reports. However, the mean population density increased due to contraction of the species＇ habitat range. We observed a population decrease of 2%-5% per year over the course of our study. Many of the assessed demographic parameters did not significantly change over the three years. This suggests that the decrease in nyala population was not due to random variations in reproduction. Anthropogenic factors such as competition with livestock for forage, habitat encroachment and poaching by the local people might have been partly responsible for the depleted population in our study areas [Current Zoology 56 （6）： 660q569, 2010].

关键词： Density Dynamics Group size Mountain nyala Movement Sex ratio

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Vegetation structural characteristics and topographic factors in the remnant moist Afromontane forest of Wondo Genet, south central Ethiopia

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Journal of Forestry Research 2013年第3期24卷 419-430页

作者： mamo Kebede Markku Kanninen Eshetu Yirdaw Mulugeta Lemenih Viikki Tropical Resources Institute (VITRI) Department of Forest Sciences University of Helsinki Hawassa university Wondo Genet College of Forestry and Natural Resources

For forest ecosystem management to be effective, knowledge of the horizontal and vertical structural diversity of a forest is essential. The moist Afromontane highlands of Wondo Genet in south-central Ethiopia present an opportunity to restore and rehabilitate and enhance the ecosystem services to be obtained from this forest sustainably. We focused on the forest structural characteristics to better understand the current forest conditions to assist in the sustainable management of this resource. A total of 75 （20 m × 20 m） quadrats were sampled and diame- ter at breast height （DBH）〉2 cm and stem height 〉2 m were measured. Species identity and abundance, elevation, slope, and aspect were recorded for each plot. Structural characteristics were computed for each plot. Relationship of topographic factors with vegetation characteristics was conducted using R-Software. A total of 72 woody species was re- corded. Whereas, the overall diameter distribution shows an inverted J-shaped curve, the basal area followed a bell-shaped pattern. Five types of population structures are revealed. The mean tree density and basal area was 397.3 ***-1 and 31.4 ***-1, respectively. Only 2.8% of the tree species have densities of 〉25 ***^-1 and the percentage dis- tribution of trees show 56.2% in the DBH class 2-10 cm, indicating that the forest is dominated by medium-sized trees. Celtis africana （8.81 ***^-1） and Pouteria adolfi-friederieii （5.13 ***^-1） make the highest contribution to the basal area and species importance value index. The families/species with the highest importance value index are ulmaceae, Fabacea and Sapotaceae. Species abundance （r2 = 0.32, p 〈0.001） and species richness （P =0.50, p 〈0.001） are positively related with tree density. Tree density is negatively related with elevation （~ = -0.36, p 〈0.001）, slope （r2 =-0.15, p 〈0.001） and aspect （r2 = -0.07, p 〈0.05）. While basal area is negatively related with elevation （r2 =-0.14, p 〈0.001）, it has a

关键词： forest structure basal area stratification topographic factors Afromontane forest

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Research of Algorithms for Segmentation and Object Recognition on Medical Images Based on Neural Networks

Research of Algorithms for Segmentation and Object Recogniti...

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作者： mamo MICHAEL 河北工业大学

学位级别：硕士

在过去十年中,实验医学研究中的硬件支持得到了积极发展,更加先进,复杂的仪器系统也出现了。与此同时,已知的算法工具不能完全满足处理由新创建的硬件记录的复杂视觉数据的速度和质量要求,也不能解决基于小波和Shearlet变换的几何(形态... 详细信息

在过去十年中,实验医学研究中的硬件支持得到了积极发展,更加先进,复杂的仪器系统也出现了。与此同时,已知的算法工具不能完全满足处理由新创建的硬件记录的复杂视觉数据的速度和质量要求,也不能解决基于小波和Shearlet变换的几何(形态、纹理)数据分析的新的紧迫问题。目前,正在尝试使用结构上反映生物系统功能的复杂人工信息处理系统。特别注意开发综合考虑研究对象具体情况的模型、方法和算法。为了解决新问题,有必要修改和开发视觉数据几何(形态、纹理)分析的计算技术,以概率神经网络的形式提供分割和机器学习算法的选择。这将提高线性结构选择的准确性、研究对象图像的视觉质量及其轮廓。为了完成本研究论文中提出的任务,开发并创造了以下新颖性:(1)一种新的识别对象分类方法,该方法在检测大津阈值和模糊聚类的使用上有所不同,这使得有可能提高识别异常和检测病理学对象(用于检测脑和乳腺肿瘤)的准确性;(2)一种用于处理和分析MRI、CXR和CT图像的技术和算法支持,其特点是引入了竞争级别和附加步骤,以基于机器学习方法确定新的CPNN函数,从而提高了确定肺边界的准确性,减少了CXR和CT图像中的病理学识别错误;(3)一种用于检测和可视化轮廓的方法,其特征在于使用改进的Shearlet变换(FFST算法),该算法允许分析图像的几何(形态、纹理)特征(通过在医学实验中评估植入物上的组织生长速率的示例)。实际意义。开发的分割算法和识别可以提高对CT和MRI图像上恶性肿瘤的检测,以及提高胸部X射线病理检测的质量。疝成形术实验研究中视觉数据的处理和分析结果可以提高相关对象的搜索和描述质量,这对确保定量组织学方法的有效性做出了重大贡献。主要研究内容如下:(1)阐述了医学图像分割的研究背景和意义,充实了国内外研究现状,制定了研究目的和任务,展示了研究的科学新颖性,并给出了主要规定。(2)基于额外开发的计算过程开发MRI图像的对象分割方法和分类算法(以肿瘤为例)。考虑MRI图像中对象的迭代阈值分割。由于病理区域(例如,脑和乳腺肿瘤)和未感染区域的灰度级不同,选择适当的全局阈值以获得理想的初始轮廓是一项挑战。基于改进的Otsu算法和模糊C均值聚类,开发了一种阈值迭代方法来对MRI图像上的对象(肿瘤)和非感染区域(大脑和乳房)进行分割。提出了一种使用所开发的分割方法、离散小波变换(DWT)和灰度交互矩阵(GLCM)对对象(脑和乳腺肿瘤)进行分类的算法。小波用于在不同尺度下分析图像的不同频率。小波定位函数的频率信息,这对分类至关重要。应用离散小波变换,生成四个子带LL(低)、HL(高-低)、LH(低-高)、HH(高),并对感兴趣区域(ROI)进行两级小波分解。当图像分解为2D级别时,将显示一个近似值,其中三个详细图像分别表示图像的低频和高频内容。为了获得更好的分类结果,针对各种偏移(2到4个像素)和角度(0°、45°、90°和135°)生成了GLCM矩阵。突出特征(基于对象-肿瘤的面积)并从分割图像中选择,然后使用神经网络方法进行分类,以诊断患者是否患有良性或恶性肿瘤。多种方法组合的实施提高了计算结果的准确性。因此,开发的分割方法和提取的特征得分很高,为医学专家提供了高质量的图像分析。(3)中描述了从交互信息过程中提取数据以处理和分析放射学中的视觉数据所开发的计算技术和算法支持。如果无法获得直接描述受损肺状态的数据,则有必要将信号与非侵入性接受源隔离。这个问题的解决方案是使用机器学习进行的。开发的算法软件可以提高诊断肺部边界、隔离肿瘤以及在CT和胸部x射线图像模糊的情况下识别病理的准确性。为了识别胸部x光图像上的物体(病理),已经开发了一种计算技术和算法支持,以自动识别物体-肺(有和没有病理)。在CPNN算法的方法中,高斯核的计算和条件概率之间出现了另一个级别(竞争级别)。分割技术用于胸片图像处理,以提取肺部区域、大小测量和不规则形状。我们使用两个数据集来衡量我们系统的性能:蒙哥马利县(MC)X射线数据集和深圳X射线数据集中。

关键词：分词神经网络剪切变换 MRI、CT、CXR图像

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基于人工神经网络的注水开发油藏产量预测

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石油勘探与开发 2020年第2期47卷 357-365页

作者： NEGASH Berihun mamo YAW Atta Dennis 马来西亚石油大学石油工程系马来西亚斯里依斯干达32610

针对传统注水开发油藏产量预测方法存在的问题,提出了基于人工神经网络的预测模型,阐述了模拟工作流程,并进行了算例分析。提出了基于流体物理学和测量数据随机组合的特征提取方法,以提高模型的预测效果。优选贝叶斯正则化算法作为模型... 详细信息

针对传统注水开发油藏产量预测方法存在的问题,提出了基于人工神经网络的预测模型,阐述了模拟工作流程,并进行了算例分析。提出了基于流体物理学和测量数据随机组合的特征提取方法,以提高模型的预测效果。优选贝叶斯正则化算法作为模型的训练算法,该算法一般耗时较长,但能对产油量、产气量、产水量等嘈杂数据集进行良好泛化。通过计算均方误差及决定系数、绘制误差分布直方图及模拟数据-验证数据交会图等方式进行模型评价。用90%的历史数据训练、验证、测试目标模型结构,然后用其余10%数据进行盲测。研究表明,提出的流体产量预测模型决定系数超过0.9,模拟结果与实际数据吻合程度高,输入信息少,计算成本低。

关键词：人工神经网络机器学习特征提取贝叶斯正则化算法产量预测注水开发

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Longevity of Juniperus procera seed lots under different storage conditions: implications for ex situ conservation in seed banks

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Journal of Forestry Research 2011年第3期22卷 453-459页

作者： Negash mamo Diriba Nigusie Mulualem Tigabu Demel Teketay Miftah Fekadu Ethiopia Agricultural Research Organization Forestry Research Centre P.O.Box 30708 Addis Ababa Ethiopia Swedish university of Agricultural Sciences Southern Swedish Forest Research Centre Tropical Silviculture and Seed Laboratory PO Box 101 SE-230 53 Alnarp Sweden university of Botswana Okavango Research Institute Private Bag 285 Maun Botswana

Juniperus procera Endl. is economically important timber species, but its populations are extremely small and fragmented in its natural habitat, thus, calling for immediate ex situ conservation. Here we examined the effects of seed sources and storage temperature on the longevity of Juniperus procera seed lots through collection and preservation of seeds in seed banks. Seeds were collected from nine sites across the species natural distribution in Ethiopia and stored in four warehouses： modern cold room （5℃）, mud house （15℃）, concrete block house （17℃ or corrugated iron house （20℃） for 42 months. Every three months, a random sample of stored seeds were drawn and tested for germination. A highly significant variation （p 0.01） in germination of stored seeds was observed among different storage environments, seed lots, and duration of storage. Over the storage period, seeds stored in the cold room had the highest mean percentage germination, followed by the mud house, corrugated house and blocket house. The cold room （41%） and the mud house （38%） maintained the same level of germination as the intitial germination of the seedlotds （42%）. The variation in longevity of stored seeds was significnatly correlated with the initial germination of seed lots （r 0.80; p 0.01）. Cold storage also resulted in enhancement of germination through its stratification effect that terminated the non-deepphysiological dormancy of juniper seeds. In conclusion, seed lots with good initial germination can be effectively stored in cold room （5℃） up to four years. In the absence of modern cold stores, mud houses can be used as a good alternative to store seeds at local level.

关键词： germination African pencil cedar Ethiopia seed zones seed storage

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Artificial neural network based production forecasting for a hydrocarbon reservoir under water injection

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Petroleum Exploration and Development 2020年第2期47卷 383-392页

作者： NEGASH Berihun mamo YAW Atta Dennis university Teknologi PETRONAS Petroleum Engineering Department32610 Seri IskandarPerak Darul RidzuanMalaysia

As the conventional prediction methods for production of waterflooding reservoirs have some drawbacks, a production forecasting model based on artificial neural network was proposed, the simulation process by this method was presented, and some examples were illustrated. A workflow that involves a physics-based extraction of features was proposed for fluid production forecasting to improve the prediction effect. The Bayesian regularization algorithm was selected as the training algorithm of the model. This algorithm, although taking longer time, can better generalize oil, gas and water production data sets. The model was evaluated by calculating mean square error and determination coefficient, drawing error distribution histogram and the cross-plot between simulation data and verification data etc. The model structure was trained, validated and tested with 90% of the historical data, and blindly evaluated using the remaining. The predictive model consumes minimal information and computational cost and is capable of predicting fluid production rate with a coefficient of determination of more than 0.9, which has the simulation results consistent with the practical data.

关键词： neural networks machine learning attribute extraction Bayesian regularization algorithm production forecasting water flooding

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Sleep deprivation and associated factors among students of the Institute of Health in Jimma university, Southwest Ethiopia

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Frontiers of Nursing 2021年第3期8卷 303-311页

作者： Bayisa Bereka Negussie mamo Solomon Emeria Ebrahim Yimam Reta Bisrat Zeleke Shiferaw Pediatrics and Child Health Nursing School of Nursing and MidwiferyJimma UniversityJimma 378Ethiopia Adult Health Nursing Department of NursingWolkite UniversityWolkiteGurhage 07Ethiopia Adult Health Nursing School of Nursing and MidwiferyJimma UniversityJimma 378Ethiopia Maternity Health Nursing Department of NursingWolkitie UniversityWolkitieGurhage 07Ethiopia

Objective:Despite getting sufficient sleep being one of the most important things that we can do to keep our body and mind healthy,sleep deprivation has become a major public health *** study aimed to determine the prevalence of sleep deprivation and its associated factors among students of the Institute of Health in Jimma ***:An institution-based cross-sectional study was conducted from April 10 to April 24 in *** were collected from 365 randomly selected participants and analyzed using Statistical Package for the Social Sciences(SPSS;version 23).Multivariate logistic regression analysis was used to identify the factors associated with sleep *** level of significance was declared at a P-value ofudy findings showed that 60.8%of students had sleep deprivation and 68.2%had sleep *** problems(adjusted odds ratio[AOR]=1.91[95%confidence interval{CI}=1.01–3.58]),alcohol consumption[AOR=0.42(95%CI=0.2–0.89)],cigarette smoking[AOR=0.31(95%CI=0.09–0.93)],khat chewing[AOR=0.47(95%CI=0.12–0.82)],use of an electronic device before bedtime[AOR=5.26(95%CI=1.78–15.52)],and cumulative grade point average(CGPA)[AOR=0.48(95%CI=0.27–0.83)]were significantly associated with sleep ***:Sleep deprivation was common in the study *** is mainly due to health problems,substance utilization,long-time use of an electronic device,and low ***,a strategy and system should be established to limit substance use,enhance proper use of electronic devices,and create awareness on the impact of nonoptimal sleep.

关键词： Ethiopia Jimma university health students sleep deprivation

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Nanoparticle type effects on flexural, interfacial and vibration properties of GFRE composites

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Chinese Journal of Aeronautics 2016年第2期29卷 520-533页

作者： u.A.Khashaba Mechanical Engineering Department Faculty of Engineering King Abdulaziz University

Damping improvement in composite structures via introducing nanofillers generally has remarkable negative effects on the other mechanical properties. Therefore, in the present work, SiC and A1203 nanoparticles＇ infusion effects on the flexural, interracial and vibration properties of epoxy matrix and glass fiber reinforced epoxy （GFR/E） laminates were investigated. unidirectional （uD-GFR/E） and quasi-isotropic （QI-GFR/E） laminates with [0/± 45/90]s and [90/±45/0]s stack- ing sequences were hybridized by the optimum nanoparticles percentages. Results from off-axis flexural strengths of uD-GFR/E demonstrate good fiber/nanophased-matrix interracial bonding. The interlaminar shear stress between the adjacent layers with different orientations/strains of duc- tile QI-GFR/SiC/E laminates results in decreasing the flexural strengths respectively by 24.3% and 9.1% for [0/±45/90]s and [90/± 45/0]s stacking sequences and increasing the dissipated interfacial friction energy and thus the damping by 105.7% and 26.1%. The damping of QI-GFR/E, QI-GFR/SiC/E and QI-GFR/AI203/E laminates with [90/± 45/0]s stacking sequence was increased by 111.4%, 29.7% and 32.9% respectively compared to [0/± 45/90]s stacking sequence.

关键词： Flexural properties GFRE composites Interracial bonding Nanoparticles Non-destructive vibrationtechnique

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General investigation for longitudinal wave propagation under magnetic field effect via nonlocal elasticity

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Applied Mathematics and Mechanics(English Edition) 2015年第10期36卷 1305-1318页

作者： u.GVEN Department of Mechanical Engineering Yildiz Technical University

In this paper, the propagation of longitudinal stress waves under a longitu- dinal magnetic field is addressed using a unified nonlocal elasticity model with two scale coefficients. The analysis of wave motion is mainly based on the Love rod model. The effect of shear is also taken into account in the framework of Bishop＇s correction. This analysis shows that the classical theory is not sufficient for this subject. However, this unified nonlocal elasticity model solely used in the present study reflects in a manner fairly realistic for the effect of the longitudinal magnetic field on the longitudinal wave propagation.

关键词： Rayleigh-Bishop rod nonlocal elasticity magnetic field wave propagation

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Physico-chemical characterization of a farmland affected by wastewater in relation to heavy metals

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Journal of Zhejiang university-Science A(Applied Physics & Engineering) 2008年第3期9卷 366-372页

作者： Emmanuel u. ONWEREMADu Department of Soil Science and Technology Federal university of Technology PMB 1526 Owerri Nigeria

This study investigated selected properties of soils affected by wastewater and its relationship with some heavy metals. A free survey technique involving target sampling was used in siting soil profile pits. Soil samples were collected based on horizon differentiation and analyzed using routine and special analytical techniques. Soil data were subjected to correlation analysis using SAS program. Results show that all heavy metals studied had values above critical limits in the polluted soils using known standards and that these biotoxic metals decreased with soil depths. Highly significant (P=0.01 and 0.05) relationships were established between investigated heavy metals and some soil properties, especially soil pH and organic matter. Further studies involving more edaphic properties, biotoxic metals and their bioaccessibility in crops growing on wastewater soils will surely enhance knowledge and management of these highly anthropogenically influenced soils of the study site.

关键词： Bioavailability Characterization Heavy metals Soil pollution Wastewater

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