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The Awassi sire can be used to crossbred with low-productive Tikur local ewes to produce export-marketable weight at yearling under farmer's management in the Ethiopian highlands

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Circular Agricultural Systems 2022年第1期2卷 17-22页

作者： Mekonnen Tilahun Belay Deribe Mesfin Lakew Solomon Abreha Negus Belayneh Abiy Shenkute Desalegn Ayechew Solomon Tiruneh Uchenna YAnele Jianchu Xu Andassa Livestock Research center P.O.Box 27Bahir DarEthiopia Sirinka Agricultural Research center P.O.Box 74WoldiaEthiopia Amhara Agricultural Research Institute(ARARI) P.O.Box 527Bahir DarEthiopia Wollo University P.O.Box 1145DessieEthiopia Debre Tabor University P.O.Box 272Debre TaborEthiopia North Carolina Agricultural and Technical State University GreensboroNC 27411USA Key Laboratory of Economic Plants and Biotechnology Kunming Institute of BotanyChinese Academy of SciencesKunming 650201China

A community-based sheep cross breeding project was conducted in Ethiopia with exotic Awassi crossbred rams and less productive indigenous Tikur ***-five Awassi crossbred rams having 46,48,56 and 65%Awassi blood levels were purchased and distributed to the participating 84 farmers which had 2,884 breeding *** overall least square mean weights for F1 and F2 generation lambs at birth,day 90,180,270 and yearling weight were 3.10±0.01,13.04±0.07,16.95±0.08,20.84±0.11 and 24.42±0.14 kg,*** weight traits were significantly affected by lambing year for birth weight(P0.05)was noted for 90-d weight(weaning weight).Season of lambing had significant effect(Pdard of 25 kg at yearling *** future of Awassi-Tikur sheep farming must focus on feed supplementation strategies and on establishing cooperatives for farmers to improve their livelihoods.

关键词： breeding weights establishing

Toward a sustainable grassland ecosystem worldwide

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The Innovation 2022年第4期3卷 15-16页

作者： Jian Sun Yi Wang Shilong Piao Miao Liu Guodong Han Junran Li Eryuan Liang Tien Ming Lee Guohua Liu Andreas Wilkes Shiliang Liu Wenwu Zhao Huakun Zhou Mesenbet Yibeltal Mulatu Liyew Berihun Dawn Browning Ayele Almaw Fenta Atsushi Tsunekawa Joel Brown Walter Willms Mitsuru Tsubo State Key Laboratory of Earth System Resources and Environment of Tibetan Plateau Institute of Tibetan Plateau ResearchChinese Academy of SciencesBeijing 100101China School of Life Sciences and School of Ecology State Key Lab of Biological ControlSun Yat-sen UniversityGuangzhou 510275China Sino-French Institute for Earth System Science College of Urban and Environmental SciencesPeking UniversityBeijing 100871China College of Grassland Science and Technology China Agricultural UniversityBeijing 100193China Key Laboratory of Grassland Resources of the Ministry of Education College of GrasslandResources and EnvironmentInner Mongolia Agricultural UniversityHohhot 010011China Department of Geosciences The University of TulsaTulsaOK 74137USA State Key Laboratory of Urban and Regional Ecology Research Center for Eco-Environmental SciencesChinese Academy of SciencesBeijing 100085China Values for Development Ltd Bury St.Edmunds IP333EQUK School of Environment Beijing Normal UniversityBeijing 100875China Faculty of Geographical Science Beijing Normal UniversityBeijing 100875China Key Laboratory of Restoration Ecology for Cold Regions in Qinghai Northwest Institute of Plateau BiologyChinese Academy of SciencesXining 810008China Faculty of Civil and Water Resource Engineering Bahir Dar Institute of TechnologyBahir Dar UniversityBahir DarEthiopia Arid Land Research center Tottori UniversityTottori 6800001Japan USDA–ARS Jornada Experimental Range Las CrucesNM 88003USA USDA NRCS Jornada Experimental RangeNew Mexico State UniversityMSC 3JERPO Box 30003Las CrucesNMUSA Agriculture and Agri-Food Canada Lethbridge Research Centre54031st Avenue SouthLethbridgeABCanada

Globally,grasslands,covering about 40%of the Earth’s land area,are vital for supporting important ecosystem functions,services,and livelihoods of millions of ***,grassland degradation is a major threat to the maintenance of ecological services,1 food security,and sustainable development,and directly hinders the global efforts with meeting goals and targets such as the The UN Decade on Ecosystem Restoration and Sustainable Development Goals(SDGs).Remote sensing approaches have the advantages of spanning large geographical areas withmultiple spatial,spectral,and temporal *** global scale,remote sensing methods used normalized difference vegetation index to determine net primary productivity(NPP),which still is the effectivemethod to indicate grassland *** master the general situation of grassland,we analyzed the global spatial-temporal variation of NPP from 2001 to 2019 at the pixel level across the *** presented in Figure 1A,the NPP values of global grasslands showed an obvious variation trend,which indicated a considerable distribution pattern of spatial *** decreasing and increasing trend in grassland NPP covered approximately 25.3%and 74.5%of the total grassland area,respectively.

关键词： grassland Figure hinder

ADMM-based Distributed Active and Reactive Power Control for Regional AC Power Grid with Wind Farms

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Journal of Modern Power Systems and Clean energy 2022年第3期10卷 588-596页

作者： Pengda Wang Qiuwei Wu Sheng Huang Canbing Li Bin Zhou center for Electric Power and energy(CEE) Department of Electrical EngineeringTechnical University of Denmark(DTU)Kgs.Lyngby 2800Denmark School of Electronic Information and Electrical Engineering Shanghai Jiao Tong UniversityShanghai 200240China College of Electrical and Information Engineering Hunan UniversityChangsha 410082China

A distributed active and reactive power control(darPC)strategy based on the alternating direction method of multipliers(ADMM)is proposed for regional AC transmission system(TS)with wind farms(WFs).The proposed darPC strategy optimizes the power distribution among the WFs to minimize the power losses of the AC TS while tracking the active power reference from the transmission system operator(TSO),and minimizes the voltage deviation of the buses inside the WF from the rated voltage as well as the power losses of the WF collection *** optimal power flow(OPF)of the TS is relaxed by using the semidefinite programming(SDP)relaxation while the branch flow model is used to model the WF collection *** the darPC strategy,the large-scale strongly-coupled optimization problem is decomposed by using the ADMM,which is solved in the regional TS controller and WF controllers in parallel without loss of the global *** boundary information is exchanged between the regional TS controller and WF *** with the conventional OPF method of the TS with WFs,the optimality and accuracy of the system operation can be ***,the proposed strategy efficiently reduces the computation burden of the TS controller and eliminates the need of a central *** protection of the information privacy can be enhanced.A modified IEEE 9-bus system with two WFs consisting of 64 wind turbines(WTs)is used to validate the proposed darPC strategy.

关键词： Alternating direction method of multipliers(ADMM) distributed active and reactive power control(darPC) optimal power flow(OPF) semidefinite programming(SDP) wind farm

Thermomechanical Behavior of Brake Drums Under Extreme Braking Conditions

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Computers, Materials & Continua 2022年第8期72卷 2259-2273页

作者： T.Khatir M.Bouchetara K.Derrar M.Djafri S.Khatir M.Abdel Wahab Institute of Science and Technology University Center Salhi Ahmed NaamaAlgeria Laboratory of Gas Combustion and Environment University of Sciences and Technology of OranL.P 1505 El-MenaouerOranUSTO 31000Algeria High School of Aeronautic Techniques dar El Beida Algeria Ho Chi Minh City Open University Ho Chi Minh CityViet Nam Faculty of Engineering Van Lang UniversityHo Chi Minh CityVietnam Soete Laboratory Faculty of Engineering and ArchitectureGhent UniversityTechnologieparkZwijnaarde 903B-9052 ZwijnaardeBelgium

Braking efficiency is characterized by reduced braking time and distance,and therefore passenger safety depends on the design of the braking *** the braking of a vehicle,the braking system must dissipate the kinetic energy by transforming it into heat energy.A too high temperature can lead to an almost total loss of braking *** excessive rise in brake temperature can also cause surface cracks extending to the outside edge of the drum friction *** transfer and temperature gradient,not to forget the vehicle’s travel environment(high speed,heavy load,and steeply sloping road conditions),must thus be the essential criteria for any brake system *** aim of the present investigation is to analyze the thermal behavior of different brake drum designs during the single emergency braking of a heavy-duty vehicle on a steeply sloping *** calculation of the temperature field is performed in transient mode using a three-dimensional finite element model assuming a constant coefficient of *** this study,the influence of geometrical brake drum configurations on the thermal behavior of brake drums with two different materials in grey cast iron FG200 and aluminum alloy 356.0 reinforced with silicon carbide(SiC)particles is analyzed under extreme vehicle braking *** numerical simulation results obtained using FE software ANSYS are qualitatively compared with the results already published in the literature.

关键词： Drum brake finite element method braking energy distribution friction heat power friction heat flux transient temperature field

Effects of urbanization on the relationship between greenspace patterns and evolution of regional heat island in cities of Ethiopia

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Chinese Journal of Population,Resources and Environment 2021年第4期19卷 330-343页

作者： Mekonnen Amberber Degefu Mekuria Argaw Gudina Legese Feyisa Sileshi Degefa Kotebe Metropolitan University Addis AbabaEthiopia center for Environmental Science Addis Ababa UniversityAddis AbabaEthiopia

Green space(GS)is a central element of urban ecosystems while,urbanization is substantially changed green land into impervious ecosystems,which has then troubled the equilibrium of the surface thermal energy and the ecosystem services *** study was intended to explore the response of relative land surface temperature(RLST)intensities to the urban ecosystem-agglomeration dynamics as well as regional thermal environment(RTE)effects on green space in four major cities(i.e.,Addis Ababa-Hawassa-Adama-bahir dar)of Ethiopia from 1990−2020,using a set of remote sensing images,single-channel algorism,and geospatial *** results showed the trends of GS evolution were:GS loss>GS gain>GS ***,the distinct ecosystems as high-temperature zones(RLST more than 2°C)were gradually augmented and significantly intensified between 2010−2020 in all cities,while the proportion of green space was significantly *** to this,the segregated urban heat islands were gradually inter-weaved and interacted with each other and forming regional heat ***,the newly established green space has fewer cooling effects than urban forest and greenery,because RLST of green space loss and gain are substantially *** also confirmed that the regional thermal environment is not only prejudiced by ecosystem patterns and processes besides substantially conquered by the particular GS change processes as well as RHI dynamics and evolution rate.

关键词： Greenery land Regional thermal environment Agglomeration Resilience