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Optimisation of superplastic processing parameters for(Cu43Zr48Al9)98Y2 bulk metallic glasses
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作者 Bing Li Xuanxuan Xu +3 位作者 Hucheng Zhang Ke Yang Xinhui Fan Jinshan Li 《中国稀土学报:英文版》 SCIE EI CAS CSCD 2019年第1期95-100,M0005共7页
In this study,hot compression tests of(Cu43Zr48Al9)98Y2 bulk metallic glasses(BMGs)were performed,and their micro structure and thermal properties after the deformation were studied to explore the appropriate range of... In this study,hot compression tests of(Cu43Zr48Al9)98Y2 bulk metallic glasses(BMGs)were performed,and their micro structure and thermal properties after the deformation were studied to explore the appropriate range of their optimum processing parameters.The experimental results show that the superplastic deformation of(Cu43Zr48Al9)98Y2 bulk metallic glasses depends mainly on the temperature and strain rate.It is suitable for superplastic processing when the alloys are in the state of Newtonian flow and do not crystallise.The appropriate processing parameters of(Cu43Zr48Al9)98Y2 BMGs are the temperatures and strain rates,which are below the"dividing line".And when the temperature is above733 K,the strain rate must be>1×10^-3 s^-1. 展开更多
关键词 BULK metallic GLASSES SUPERPLASTIC Flow BEHAVIOUR Crystallisation BEHAVIOUR RARE earths
Microstructural Characteristics and Mechanical Properties of Low-Alloy, Medium-Carbon Steels After Multiple Tempering
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作者 Erfan Abbasi Quanshun Luo Dave Owens 《金属学报:英文版》 SCIE EI CAS CSCD 2019年第1期74-88,共15页
The microstructure and mechanical properties of NiCrMoV-and NiCrSi-alloyed medium-carbon steels were investigated after multiple tempering. After austenitising, the steels were hardened by oil quenching and subsequent... The microstructure and mechanical properties of NiCrMoV-and NiCrSi-alloyed medium-carbon steels were investigated after multiple tempering. After austenitising, the steels were hardened by oil quenching and subsequently double or triple tempered at temperatures from 250 to 500 °C. The samples were characterised using scanning electron microscopy and X-ray diffraction, while the mechanical properties were evaluated by Vickers hardness testing, V-notched Charpy impact testing and tensile testing. The results showed that the retained austenite was stable up to 400 °C and the applied multiple tempering below this temperature did not lead to a complete decomposition of retained austenite in both steels. It was also found that the microstructure, hardness and impact toughness varied mainly as a function of tempering temperature,regardless of the number of tempering stages. Moreover, the impact toughness of NiCrMoV steel was rather similar after single/triple tempering at different temperatures, while NiCrSi steel exhibited tempered martensite embrittlement after single/double tempering at 400 °C. The observed difference was mainly attributed to the effect of precipitation behaviour due to the effect of alloying additions in the studied steels. 展开更多
关键词 MEDIUM-CARBON steels MULTIPLE TEMPERING Alloying addition MECHANICAL properties RETAINED AUSTENITE Precipitation behaviour
Effect of phosphatation and calcination on the environmentalbehaviour of sediments 预览
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作者 Moussa Dia Rachid Zentar +3 位作者 Nor-edine Abriak Ange Nzihou Guy Depelsenaire Alain Germeau 《国际泥沙研究:英文版》 SCIE 2019年第5期486-495,共10页
Dredging operations produce considerable quantities of materials, to be managed and this opens an opportunity for valorization in civil engineering. However, the contamination of the dredged sediments has become a maj... Dredging operations produce considerable quantities of materials, to be managed and this opens an opportunity for valorization in civil engineering. However, the contamination of the dredged sediments has become a major problem to solve. The major contaminants are heavy metals and organic compounds. This study focuses on the use of phosphoric acid (H3PO4) to stabilize heavy metals from sediments and destroy organic matter by calcination at 650 °C with a goal of using sediments in roadworks. Several studies have been conducted in this eld. The stabilized materials obtained have been used in civil engineering. The main purpose of this work is to discuss the environmental behavior of marine sediment treated by phosphatation and calcination. Two types of phosphoric acids were used. The pH dependence leaching test has been used as the basic characterization to evaluate the effect of the type of phosphoric acid on the metals behavior in a valorization scenario. The standard leaching test and the Toxicity Characteristic Leaching Procedure (TCLP) were conducted as compliance tests. In regards of the obtained results, the environmental assessment has also shown a reduction in the availability of targeted heavy metals in alkaline environment whatever the type of acid used for treatment. This opens opportunities for co-valorization. 展开更多
关键词 Polluted SEDIMENTS HEAVY metals Phosphatation CALCINATION and environmental BEHAVIOUR
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Improving Railway Passengers Experience:Two Perspectives 预览
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作者 Mark van Hagen Niels van Oort 《交通与运输工程:英文版》 2019年第3期97-110,共14页
This paper describes two perspectives to improve the passenger experience.The passenger satisfaction pyramid is introduced,consisting of the base of the pyramid(dissatisfiers)focusing on time well saved and the top of... This paper describes two perspectives to improve the passenger experience.The passenger satisfaction pyramid is introduced,consisting of the base of the pyramid(dissatisfiers)focusing on time well saved and the top of the pyramid(satisfiers)aiming at time well spent.The challenge in planning and design of public transport services is to find the most efficient(set of)design choices.Depending on the context this might either mean focusing on the top or on the bottom of the pyramid.We found that influencing and enhancing the qualities of the satisfiers is far more important than traditional studies showed us.For stations,regression analyses show that dissatisfiers are responsible for explaining almost half of the total score of the station and satisfiers are responsible for the other half of the scores passengers give for the station.We still have to put a lot of energy in getting the basics right,starting in the planning phase,but then we are not allowed to lean back.We have to keep investing in qualities like ambience,comfort and experience which makes the customers truly happy at the end of the day. 展开更多
关键词 PASSENGER EXPERIENCE service reliability PERCEPTION BEHAVIOUR
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Observational study to assess pregnant women’s knowledge and behaviour related to toxoplasmosis in Essaouira province, Morocco
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作者 Nadia Ouzennou Samia Boussaa +1 位作者 Safa Ben Alla Ali Boumezzough 《亚太热带医药杂志:英文版》 SCIE CAS 2019年第2期87-90,共4页
Objective: To assess knowledge and behaviour related to toxoplasmosis which remains a neglected disease in Morocco.Methods: Observational investigations were conducted among 600 pregnant women from Essaouira Province.... Objective: To assess knowledge and behaviour related to toxoplasmosis which remains a neglected disease in Morocco.Methods: Observational investigations were conducted among 600 pregnant women from Essaouira Province.The interview items covered respondents’ knowledge of the disease, its preventive practices and risk behaviours.Results: A total of 22/600 women had already carried out the anti-toxoplasmosis test, while, 96% have never done any screening of anti-Toxoplasma antibodies.Only 16/600 women have good information about the disease, its mode of transmission and its complications in both the fetus and his mother.Although most women adopt a healthy diet, the consumption of raw or undercooked meat is far to be considered as a risk factor, along with other potential factors that may foster the acquisition of the disease, such as possessing a domestic cat, educational status and knowledge of the disease.However, in this study, contact with soil was revealed the most important risk factor(P = 0.045), followed by the hygiene conditions after handling raw meat(P = 0.048).Conclusion: The underestimation of the Toxoplasma gondii sero-prevalence in Essaouira Province can be explained by the absence of toxoplasmosis serology in health institutions, as well as the gap of knowledge about the disease by local population. 展开更多
关键词 TOXOPLASMOSIS KNOWLEDGE Risk BEHAVIOUR PREGNANT WOMEN Morocco
Shared Control of Highly Automated Vehicles Using Steer-By-Wire Systems 预览
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作者 Chao Huang Fazel Naghdy +1 位作者 Haiping Du Hailong Huang 《自动化学报:英文版》 CSCD 2019年第2期410-423,共14页
A shared control of highly automated Steer-by-Wire system is proposed for cooperative driving between the driver and vehicle in the face of driver’s abnormal driving. A fault detection scheme is designed to detect th... A shared control of highly automated Steer-by-Wire system is proposed for cooperative driving between the driver and vehicle in the face of driver’s abnormal driving. A fault detection scheme is designed to detect the abnormal driving behaviour and transfer the control of the car to the automatic system designed based on a fault tolerant model predictive control(MPC) controller driving the vehicle along an optimal safe path.The proposed concept and control algorithm are tested in a number of scenarios representing intersection, lane change and different types of driver’s abnormal behaviour. The simulation results show the feasibility and effectiveness of the proposed method. 展开更多
关键词 DRIVER BEHAVIOUR HIGHLY automation SHARED control STEER-BY-WIRE system
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Influence of solution treatment on microstructure, corrosion resistance, and oxidation behavior of cast G-NiCr28W alloy
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作者 Alptekin Kisasoz 《中国铸造:英文版》 SCIE 2019年第1期63-70,共8页
G-NiCr28W is a nickel-based cast alloy. Its microstructure consists of nickel-rich matrix phase and chromium-rich eutectic carbides. The solution treatment process can provide homogenous microstructure and desired mec... G-NiCr28W is a nickel-based cast alloy. Its microstructure consists of nickel-rich matrix phase and chromium-rich eutectic carbides. The solution treatment process can provide homogenous microstructure and desired mechanical/thermal properties for G-NiCr28W alloy. However, the solution treatment process affects the corrosion resistance of the alloy and it causes metal loss due to the occurrence of oxidation at atmospheric conditions. Therefore, determining the changes in the properties of the G-NiCr28W is important. For this purpose, G-NiCr28W specimens were solution treated at 1,040 ℃, 1,100 ℃ and 1,160 ℃ for 1 h and 8 h, respectively. The microstructures of the solution-treated samples were characterized by optical microscopy, scanning electron microscopy, energy dispersive spectroscopy and X-ray diffraction analysis. Moreover, hardness, corrosion resistance and oxidation behaviors of the solution-treated samples were examined. The solution treatment process applied at 1,160 ℃ led to the formation of Fe2W2C blocky carbides, and hardness of the sample increased with the existence of blocky carbides, while corrosion resistance decreased. Furthermore, excessive metal loss occurred depending on oxidation due to the high process temperature at 1,160 ℃. 展开更多
关键词 G-NiCr28W nickel-based ALLOY heat treatment corrosion behaviour OXIDATION
Thixotropy of Systems with Shear Thinning and Plastic Flow Behavior 预览
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作者 Dimiter Hadjistamov 《材料科学与工程:中英文B版》 2019年第2期56-65,共10页
The definition of the thixotropy is a decrease in viscosity with time in shear and a subsequent recovery of viscosity after the shear deformation is removed.We used therefore start-up experiments with constant shear r... The definition of the thixotropy is a decrease in viscosity with time in shear and a subsequent recovery of viscosity after the shear deformation is removed.We used therefore start-up experiments with constant shear rates and can speak consequently of shear stress instead of viscosity.The shear stress increases sharply at the beginning of the stress growth experiment,passes an overshoot and begins to decrease up to the steady state shear stress.We can assume that a stress growth curve with an overshoot points out to thixotropic behavior.After the steady state shear stress is reached,the shear deformation is stopped,and the stress relaxation begins.It is to be expected that the shear stress will recover after the stress relaxation.Systems with shear thinning and plastic flow behavior were examined.The thixotropy is discussed in relation to the flow behavior.Stress growth experiments were performed with shear rates from the first Newtonian region and from the shear thinning region of the systems with shear thinning flow behavior.Stress start-up experiments were carrying out with shear rates from the first and second yield stress regions and from the transition section of a system with plastic flow behavior. 展开更多
关键词 THIXOTROPY rheopexy SYSTEMS with SHEAR THINNING FLOW BEHAVIOR SYSTEMS with plastic FLOW BEHAVIOR time related FLOW behaviour.
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Phenomenological modelling of flow behaviour of 20MnMoNi55 reactor pressure vessel steel at cryogenic temperature with different strain rates 预览
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作者 Swagatam Paul Partha Dey +3 位作者 Snehasish Bhattacharjee Sanjib Kumar Acharyya Prasanta Sahoo Jayanta Chattopadhyay 《Defence Technology(防务技术)》 CAS CSCD 2019年第3期326-337,共12页
In the present study a phenomenological constitutive model is developed to describe the flow behaviour of 20MnMoNi55 low carbon reactor pressure vessel (RPV) steel at sub-zero temperature under different strain rates.... In the present study a phenomenological constitutive model is developed to describe the flow behaviour of 20MnMoNi55 low carbon reactor pressure vessel (RPV) steel at sub-zero temperature under different strain rates. A set of uniaxial tensile tests is done with the variation of strain rates and temperature ranging from 10^-4s^-1 to 10^-1s^-1 and -80℃ to 140℃ respectively. From the experimental data, family of flow curves at different temperatures and strain rates are generated and fitted exponentially. The strain rate and temperature dependence of the coefficients of the exponential flow curves are extracted from these curves and characterised through a general phenomenological constitutive coupled equation. The coefficients of this coupled equation are optimised using genetic algorithm. Finite element simulation of tensile tests at different strain rates and temperatures are done using this coupled equation in material model of Abaqus FEA software and validated with experimental results. The novelties of proposed model are:(a) it can predict precisely the flow behaviour of tensile tests (b) it is a simple form of equation where fitting parameters are both function of strain rate ratio and temperature ratio,(c) it has ability to characterize flow behaviour with decreasing subzero temperatures and increasing strain rates. 展开更多
关键词 Flow BEHAVIOUR RPV steel CRYOGENIC temperature STRAIN RATE
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Synthesis, Structure and Decarboxylative Behavior of a Nitro-coordinated Potassium Compound 预览
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作者 李东密 崔佳佳 +2 位作者 姚佳欣 李召好 赵邦屯 《结构化学》 SCIE CAS CSCD 2019年第3期362-368,共7页
A novel nitro-coordinated potassium compound [K(Htdc)(H2O)]n(tdc = 3-nitro-thiophene-2,5-dicarboxylate), has been synthesized and characterized. The complex with a two-dimensional(2D) layer structure contains an infin... A novel nitro-coordinated potassium compound [K(Htdc)(H2O)]n(tdc = 3-nitro-thiophene-2,5-dicarboxylate), has been synthesized and characterized. The complex with a two-dimensional(2D) layer structure contains an infinite K-O ladder-shaped chain, which is connected through carboxyl and unusual nitro-coordination of Htdc– anion. Then the 2D layers are further extended by intermolecular hydrogen-bonding to form a three-dimensional(3D) supramoleculalr network. Variable temperature powder X-ray diffractions, thermogravimetric analysis and nuclear magnetic resonance studies exhibit that the compound has a thermal-induced decarboxylative behavior. 展开更多
关键词 crystal STRUCTURE COORDINATION mode two-dimensional COMPOUND decarboxylative behaviour
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Effects of splined shaft bending rigidity on cylinder tilt behaviour for high-speed electrohydrostatic actuator pumps
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作者 Junhui ZHANG Yuan CHEN +2 位作者 Bing XU Min PAN Qun CHAO 《中国航空学报:英文版》 SCIE EI CAS CSCD 2019年第2期499-512,共14页
High-speed axial piston pumps are hydraulic power supplies for electro-hydrostatic actuators(EHAs). The efficiency of a pump directly affects the operating performance of an EHA, and an understanding of the physical p... High-speed axial piston pumps are hydraulic power supplies for electro-hydrostatic actuators(EHAs). The efficiency of a pump directly affects the operating performance of an EHA, and an understanding of the physical phenomena occurring in the cylinder/valve plate interface is essential to investigate energy dissipation. The effects of the splined shaft bending rigidity on the cylinder tilt behaviour in an EHA pump need to be considered, because the deflection and radial expansion of a steel shaft rotating at a high speed cannot be ignored. This paper proposes a new mathematical model to predict the cylinder tilt behaviour by establishing a quantitative relationship between the splined shaft deflection, the cylinder tilt angle, and the tilt azimuth angle. The moments exerted by the splined shaft are included in the equilibrium equation of the cylinder. The effects of solid and hollow splined shafts equipped in an EHA pump prototype are compared at variable speeds of 5000–10,000 r/min. With a weight saving of 29.7%, the hollow shaft is experimentally found to have almost no influence on the volumetric efficiency, but to reduce the mechanical efficiency by 0.6–2.4%. The results agree with the trivial differences of the simulated central gap heights of the interface between the two shafts and the enlargement of the simulated tilt angles by the hollow shaft. The findings could guide designs of the cylinder/valve plate interface and the splined shaft to improve both the efficiency and power density of an EHA pump. 展开更多
关键词 Electro-hydrostatic ACTUATOR pump Mathematical models RIGIDITY Splined SHAFT DEFLECTION TILT BEHAVIOUR prediction
The inhomogeneous diffusion of chemically crosslinked polyacrylamide hydrogel based on poroviscosity theory
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作者 ZHENG ShouJing LI ZiQian LIU ZiShun 《中国科学:技术科学英文版》 SCIE EI CAS CSCD 2019年第8期1375-1384,共10页
The diffusion of hydrogels is a phenomenon not only profound in novel applications of mechanical engineering but also very common in nature. Comprehensive studies of the swelling properties under stable states have be... The diffusion of hydrogels is a phenomenon not only profound in novel applications of mechanical engineering but also very common in nature. Comprehensive studies of the swelling properties under stable states have been carried out in the past several years;however, ambiguities in the understanding of the kinetic behaviour of the diffusion phenomenon of hydrogels still remain.The potential applications of hydrogels are confined due to the lack of perceptiveness of the kinetic behaviour of diffusion in hydrogels. Based on our previous work, in this study, we initiate the theoretical kinetic study of the inhomogeneous diffusion of hydrogels. With poroviscosity introduced, we develop a theory for the inhomogeneous diffusion of hydrogels. After implementing this theory into the finite element solution, we could predict the water content in the hydrogel as a function of time and location. The quantitative prediction of the inhomogeneous diffusion and the formulas are given in the numerical study.Furthermore, the corresponding experiments are carried out to substantiate this theory. It can be observed that the theoretical prediction meets fairly well with our experimental data. Finally, we carry out a systematic parameter study to discuss the effect of three important parameters on the diffusion property. The increase of the interaction parameter is seen to constrain the diffusion while increase of the chemical potential is seen to facilitate the process. The change of the diffusion coefficient D, on the other hand, does not affect the process much. By comparing the conclusions above with the experimental data, we can narrow down the range of the values of χ and D. 展开更多
关键词 INHOMOGENEOUS DIFFUSION HYDROGEL poroviscosity KINETIC BEHAVIOUR
不同月龄断奶对英纯血马驹行为的影响 预览
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作者 肖海霞 托乎提·阿及德 +6 位作者 谢立荣 石国庆 张莉 毋状元 李海 帕热哈提江·吾甫尔 依巴代提·马木提 《西南农业学报》 CSCD 北大核心 2019年第3期665-672,共8页
【目的】本文研究了英纯血马驹断奶应激行为最少的适宜断奶月龄。【方法】选用15对英纯血马驹和它们的母马,根据断奶年龄马驹被分成6,7和8月龄3个组。采用群组突然断奶法通过摄像机观察马驹断奶前3d、断奶当天和断奶后8d的15个行为,统... 【目的】本文研究了英纯血马驹断奶应激行为最少的适宜断奶月龄。【方法】选用15对英纯血马驹和它们的母马,根据断奶年龄马驹被分成6,7和8月龄3个组。采用群组突然断奶法通过摄像机观察马驹断奶前3d、断奶当天和断奶后8d的15个行为,统计所有行为并应用R2.14.2语言进行分析。【结果】发现与断奶前相比,所有马驹断奶当天和断奶后的饮水、排尿、小跑和侵略行为频率都有所增加,而站、躺和个人翻滚的行为有所下降,其中断奶当天排尿、排便、相互踢打行为频率显著高于断奶前和断奶后(P<0.05),而饮水行为显著高于断奶前(P<0.05)。与7和8月龄马驹相比,6月龄马驹所表现出来的断奶应激行为最少。【结论】采用群组突然断奶法时,6月龄是英纯血马驹较合适的断奶年龄。 展开更多
关键词 英纯血 马驹 断奶 行为
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SOME RECENT PROGRESS ON STOCHASTIC HEAT EQUATIONS 预览
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作者 胡耀忠 《数学物理学报:B辑英文版》 SCIE CSCD 2019年第3期874-914,共41页
This article attempts to give a short survey of recent progress on a class of elementary stochastic partial differential equations (for example, stochastic heat equations) driven by Gaussian noise of various covarianc... This article attempts to give a short survey of recent progress on a class of elementary stochastic partial differential equations (for example, stochastic heat equations) driven by Gaussian noise of various covariance structures. The focus is on the existence and uniqueness of the classical (square integrable) solution (mild solution, weak solution). It is also concerned with the Feynman-Kac formula for the solution;Feynman-Kac formula for the moments of the solution;and their applications to the asymptotic moment bounds of the solution. It also briefly touches the exact asymptotics of the moments of the solution. 展开更多
关键词 GAUSSIAN random field GAUSSIAN noise STOCHASTIC partial differential EQUATION (stochastic heat equation) Feynman-Kac FORMULA for the solution Feynman- Kac FORMULA for the moments of the solution chaos expansion hypercontractivity moment bounds HOLDER CONTINUITY joint HOLDER CONTINUITY asymptotic behaviour Trotter-Lie FORMULA Skorohod integral
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笼内产蛋窝布置方式对蛋种鸡行为生理及死淘率的影响 预览
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作者 石海鹏 郑炜超 +3 位作者 童勤 张智 李保明 王连增 《农业工程学报》 EI CAS CSCD 北大核心 2019年第8期245-251,共7页
现行蛋种鸡本交笼虽具备较大活动空间并能满足鸡只自然交配行为,但其饲养环境依然相对贫瘠,缺乏环境富集装置,存在啄羽啄肛等行为问题。该文探究了蛋种鸡本交笼中3种不同类型产蛋窝的使用效果及其对啄羽啄肛行为及生理应激反应的影响。... 现行蛋种鸡本交笼虽具备较大活动空间并能满足鸡只自然交配行为,但其饲养环境依然相对贫瘠,缺乏环境富集装置,存在啄羽啄肛等行为问题。该文探究了蛋种鸡本交笼中3种不同类型产蛋窝的使用效果及其对啄羽啄肛行为及生理应激反应的影响。结果表明,3种产蛋窝Nest1(长×宽×高)(90 cm×40 cm×60 cm)、Nest2(45 cm×40 cm×60 cm)、Nest3(70cm×52cm×60cm)在32周龄时窝内蛋比例分别为80.5%±7.8%、67.4%±8.1%、87.3%±7.6%,Nest1与Nest3窝内蛋比例、探窝次数及趴卧次数显著高于Nest2(P<0.05),Nest1、Nest2、Nest3产蛋鸡只探窝时间无显著差异,设置产蛋窝后鸡只发出的攻击性啄、严重啄羽、轻度啄羽频次显著低于对照组(P<0.05)。3种产蛋窝血浆皮质酮浓度无显著差异,但显著低于对照组(P<0.05),对照组及Nest2总死淘率显著高于Nest1与Nest3(P<0.05),对照组因啄死淘率显著高于Nest1、Nest2、Nest3(P<0.05)。产蛋窝的设置可以满足鸡的行为需求,降低啄羽啄肛行为的发生、生理应激及因啄死淘发生风险。 展开更多
关键词 动物 生理 行为 蛋种鸡 本交笼 产蛋窝 啄羽 皮质酮 死淘率
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A pigeon-inspired optimization algorithm for many-objective optimization problems
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作者 Zhihua CUI Jiangjiang ZHANG +4 位作者 Yechuang WANG Yang CAO Xingjuan CAI Wensheng ZHANG Jinjun CHEN 《中国科学:信息科学(英文版)》 SCIE EI CSCD 2019年第7期131-138,共8页
Dear editor,Swarm intelligence optimization algorithms are inspired by the behaviour of biological groups in nature. Such algorithms have the advantages of a clear structure, simple operation, comprehensible principle... Dear editor,Swarm intelligence optimization algorithms are inspired by the behaviour of biological groups in nature. Such algorithms have the advantages of a clear structure, simple operation, comprehensible principles, strong parallelism, effective search abilities, and strong robustness. They can effectively solve difficult problems that traditional methods cannot. 展开更多
关键词 BEHAVIOUR comprehensible PRINCIPLES TRADITIONAL methods
Mechanical properties and corrosion behavior of selective laser melted 316L stainless steel after different heat treatment processes
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作者 Decheng Kong Chaofang Dong +6 位作者 Xiaoqing Ni Liang Zhang Jizheng Yao Cheng Man Xuequn Cheng Kui Xiao Xiaogang Li 《材料科学技术学报:英文版》 SCIE EI CAS CSCD 2019年第7期1499-1507,共9页
Irregular grains, high interfacial stresses and anisotropic properties widely exist in 3D-printed metallic materials, and this paper investigated the effects of heat treatment on the microstructural, mechanical and co... Irregular grains, high interfacial stresses and anisotropic properties widely exist in 3D-printed metallic materials, and this paper investigated the effects of heat treatment on the microstructural, mechanical and corrosion properties of 316 L stainless steel fabricated by selective laser melting. Sub-grains and low-angle boundaries exist in the as-received selective laser melted(SLMed) 316 L stainless steel. After heat treatment at 1050℃, the sub-grains and low-angle boundaries changed slightly, and the stress state and strength decreased to some extent due to the decrease of dislocation density. After heat treatment at 1200℃, the grains became uniform, and the dislocation cells vanished, which led to a sharp decline in the hardness and strength. However, the ductility was improved after recrystallization heat treatment.The passive film thickness and corrosion potential of the SLMed 316 L stainless steel decreased after heat treatment, and the pitting potential also decreased due to the accelerated transition from metastable to steady-state pitting;this accelerated transition was caused by the presence of weak passive films at the enlarged pores after heat treatment, especially for an adequate solid solution treatment. 展开更多
关键词 316L STAINLESS steel SELECTIVE LASER MELTING Heat treatment Microstructure Mechanical property Corrosion behaviour
Feed particle selection and nutrient intake altered by pecking stone consumption and beak length in free-range laying hens
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作者 Zafar Iqbal Kelly Drake +2 位作者 Robert A.Swick Rider A.Perez-Maldonado Isabelle Ruhnke 《动物营养:英文版》 2019年第2期140-147,共8页
The present study investigated the effects of pecking stones on feeding behaviour of hens from 16 to 46 weeks of age. Eighteen flocks of Hy-Line Brown hens were housed in 2 commercial free-range housing systems. Farm ... The present study investigated the effects of pecking stones on feeding behaviour of hens from 16 to 46 weeks of age. Eighteen flocks of Hy-Line Brown hens were housed in 2 commercial free-range housing systems. Farm A housed 10 flocks of beak trimmed(infrared beak treatment) hens in fixed sheds. Farm B housed 8 flocks of hens with intact beaks in mobile sheds. On each farm, flocks were equally assigned to control groups(no access to pecking stones) and treatment groups(access to pecking stones). Data were evaluated every 10 weeks. At each time point, 10 hens per flock were housed in individual pens, and each hen was provided with 250 g of mash diet and ad libitum water for 24 h. After 24 h, feed samples were collected and used to determine 24-h feed intake. Nutrient and particle selection was measured by subtracting nutrients and particles present in the leftover feed from the vaules obtained in the offered feed and expressed the change(A). In addition, pecking stone consumption was recorded for each flock.Data were analysed separately for each farm using fixed effects of pecking stone availability and hen age.Spearman’s rho correlation coefficients and linear regression models were constructed to evaluate the relationship of beak length and pecking stone usage, discrete mean particle size(dMEAN) consumption(△ dMEAN), and △ nutrient intake. Hens with access to pecking stones consumed significantly lower quantities of large feed particles(>2.8 mm) on farm A(P = 0.029) and selected significantly more fine particles, on farm B(P = 0.013). Overall, positive relationships(P = 0.001) between beak length and pecking stone consumption, A dMEAN, and A phosphorus consumption were observed. In conclusion,pecking stone consumption resulted in reduced selection and consumption of feed particles in hens housed on both farms. Further research is warranted to investigate the effect of pecking stones on sensory innervation of the beak. 展开更多
关键词 POULTRY WELFARE Feeding behaviour Nutrition Environmental ENRICHMENT
Electrochemical Co-reduction of Bi(Ⅲ)and Y(Ⅲ)and Extracting Yttrium from Molten LiCl-KCl Using Liquid Bi as Cathode
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作者 LI Mei LIU Yichuan +4 位作者 SUN Zhongxuan HAN Wei ZHANG Milin YANG Xiaoguang SUN Yang 《高等学校化学研究:英文版》 SCIE CAS CSCD 2019年第1期60-64,共5页
The electrochemical reaction of Bi(Ⅲ)and co-reduction behaviour of Bi(Ⅲ)and Y(Ⅲ)ions were researched in molten LiCl-KCl on a ttmgsten(W)electrode employing a range of electrochemical teclmiques.Cyclic voltammetric ... The electrochemical reaction of Bi(Ⅲ)and co-reduction behaviour of Bi(Ⅲ)and Y(Ⅲ)ions were researched in molten LiCl-KCl on a ttmgsten(W)electrode employing a range of electrochemical teclmiques.Cyclic voltammetric and square-wave voltanunetric results revealed that the reduction of Bi(Ⅲ)was a one-step process,with the exchange of three electrons on a W electrode,and diffusion-controlled.The electrochemical curves showed two reduction peaks pertaining to the formation of Bi-Y alloy compounds,because of the co-reduction of Bi(Ⅲ)and Y(Ⅲ) by metallic Y deposited on the pre-deposited Bi-coated W electrode and reacting with Bi metal in molten LiCl-KCl. Furthermore,galvanostatic electrolysis was conducted using liquid Bi as cathode to extract yttrium at different current intensities,and the extractive products were analyzed by SEM,EDS and XRD.The results indicated that BiY intermetallic compotmd was formed in the molten LiCl-KCl-YCl3 system. 展开更多
关键词 ELECTROCHEMICAL co-reduction:Electrochemical behaviour Bi-Y intennetallic compound GALVANOSTATIC ELECTROLYSIS
Parents’ and caregivers’ attitudes towards malaria, and health care seeking practices for their febrile children in a hospital in north-eastern Nigeria 预览
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作者 Mohammed Abba Mustapha Ahmed Dahiru Balami 《健康与行为进展(英文)》 2019年第1期69-74,共6页
Despite the very high burden of malaria among children in Borno state, the proportion of those who receive standard treatment has been very low. This study aimed to determine malaria knowledge, attitude towards preven... Despite the very high burden of malaria among children in Borno state, the proportion of those who receive standard treatment has been very low. This study aimed to determine malaria knowledge, attitude towards prevention, and health care seeking behaviours of parents or caregivers of children presenting with fever at the paediatric clinic of a secondary-level hospital in Maiduguri, Borno state, Nigeria. A cross-sectional study design was used to obtain information from the respondents. Data were collected using a structured questionnaire, from the parents or caregivers of children presented to the Paediatric clinic with history of fever, and analysed in SPSS. A total of 331 respondents were finally recruited into the study. The ages of the children ranged from one to fourteen years. Some of them (15.3%) were internally displaced persons (IDPs). As many as 90.7% and 91.9% of the respondents believed that malaria is a life-threatening illness, and ITNs could prevent malaria, respectively. Less than a half of them (42.3%) had immediately brought their children to the hospital once they detected the fever. At the hospital, only 202 (60.7%) of the children had had malaria parasite test done on them, of which 89.1% tested positive. Permanent residents were more likely to promptly take their children to the hospital, one they detected fever, compared to IDPs ( 2=12.401, df =1, p=0.002). There is the need for promoting early presentation of febrile children to health centres, and also promoting routine malaria tests for febrile persons. 展开更多
关键词 MALARIA ATTITUDES health care seeking behaviour FEVER CHILDREN
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