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The ecological adaptability of cloned sheep to free-grazing in the Tengger Desert of Inner Mongolia,

Xinxin LI,Huijuan WANG,Guanghua SU,Zhuying WEI,Chunling BAI,Wuni-MENGHE,Yanhui HOU,Changqing YU,Shorgan BOU,Guangpeng LI

《农业科学与工程前沿(英文)》 2014年 第1卷 第3期   页码 191-200 doi: 10.15302/J-FASE-2014029

摘要: Since the birth of the first cloned sheep, somatic cell nuclear transfer technology has been successfully used to clone a variety of mammals. Cloned livestock have no apparent health risks, and the quality and safety of the cloned animal products are similar to non-cloned animals. The social behavior and environmental adaptability of postnatal cloned animals, especially when used for grassland farm production purposes, is unknown. In the present study, the cloned Dorper sheep equipped with GPS location devices were free-grazed in a harsh natural environment similar to conditions commonly experienced by Mongolian sheep. The main findings of this research were as follows. (1) Under free-grazing conditions, the cloned sheep showed excellent climatic and ecological adaptability. In extreme temperature conditions ranging from -30 to 40°C, the cloned sheep maintained acceptable body condition and behaved as other sheep. (2) The cloned sheep quickly adapted from a herd feeding strategy to the harsh environment and quickly exhibited a grazing regimen as other free-grazing sheep. (3) The cloned sheep exhibited free-grazing patterns and social behavior as other sheep. (4) The cloned sheep in the harsh environment thrived and produced healthy lambs. Overall, the cloned Dorper sheep exhibited excellent ecological adaptation, which is an important consideration for breeding meat sheep by cloning. The Dorper sheep readily adapted to the free-grazing conditions on the Mongolian plateau grassland, which attests to their ability to withstand harsh environmental conditions.

关键词: somatic cell nuclear transfer     free-grazing synchronization     Dorper sheep     cloned animal ecology    

Error analysis of the parameters for non-coaxial grazing X-ray microscope

ZHAO Lingling, HU Jiasheng, LI Xiang

《机械工程前沿(英文)》 2007年 第2卷 第3期   页码 323-329 doi: 10.1007/s11465-007-0057-z

摘要: A non-coaxial grazing X-ray microscope, consisting of four spherical mirrors, is designed for diagnosis of inertial confinement fusion (ICF). The aberrations and imaging quality of the microscope are analyzed. To acquire excellent imaging quality, suitable tolerances for manufacturing and assembling the microscope are necessary. This paper researches the changes of Gauss parameters and aberrations due to component and subsystem parameters (such as the radius of the mirror, angle between mirrors, grazing angle, object distance, etc.). Here, spot diagrams and modulation transfer function (MTF) are first adopted to quantitatively evaluate the imaging quality of the microscope. Suitable manufacturing tolerances of components and assembly tolerances of the system are established on the basis of the discussion and analysis. A set of non-coaxial grazing X-ray microscopes is manufactured based on the tolerances. In site tests of ICF, the images with high resolution are obtained by the microscope.

关键词: non-coaxial     spherical     manufacturing     necessary     diagnosis    

导航卫星双向伪距时间同步

谭述森

《中国工程科学》 2006年 第8卷 第12期   页码 70-74

摘要:

针对卫星导航系统时间同步需求,提出了导航卫星双向伪距时间同步的理论根据,并就4种基本同步方法(双向无线电伪距同步方法, 星地双向激光伪距同步方法,双向卫星中继无线电伪距同步方法, 双向地球站中继无线电伪距同步方法)与应用进行了分析,与目前国际导航卫星时间同步通用方法相比,具有精度高, 方法简单,设备负担轻特点。

关键词: 导航卫星     伪距     时间同步    

具有任意有限延迟耦合布尔网络的完全同步 Research Articles

Jie LIU, Lulu LI, HabibM. FARDOUN

《信息与电子工程前沿(英文)》 2020年 第21卷 第2期   页码 281-293 doi: 10.1631/FITEE.1900438

摘要: 研究耦合延迟布尔网络完全同步性问题。文中所讨论的耦合延迟布尔网络模型中,状态延迟和输出延迟可能不相等,并且每个布尔网络中的状态延迟也可能不相等。基于矩阵半张量积获得耦合延迟布尔网络达到完全同步的充要条件。提供解决耦合延迟布尔网络完全同步性的有效算法。最后,通过数值算例说明该算法的有效性。

关键词: 布尔网络;同步性;时滞    

我国草原生产力

侯扶江,王春梅,娄珊宁,侯向阳,呼天明

《中国工程科学》 2016年 第18卷 第1期   页码 80-93 doi: 10.15302/J-SSCAE-2016.01.011

摘要:

分析我国草原植物生产和动物生产,比较国内外草原生产力。结果表明,在过去的30余年中,我国一部分草原产草量下降,局部变化不显著。世界草原对畜产品生产的贡献率为40.08 %,中等收入国家为67.35 %。全球24.1 %的牛肉和31.9 %的羊肉来自草原,低收入国家草原载畜量分别高出高收入国家和中等收入国家87.4 %和66.4 %,畜产品生产分别只有两者的37.3 %和71.9 %。适宜的放牧利用,可使我国的草原生产能力达到6.35×109畜产品单位(APU);全国草原单纯依靠放牧每年可产肉2.959×106 t,占全国肉类总产量的3.5 %,占全国牛羊肉总产量的27.4 %。通过草原畜牧业的现代化转型可接近高收入国家水平,增产潜力约为50 %~200 %。

关键词: 草原生产力     产草量     放牧     载畜量     畜产品单位(APU)    

基于混沌电路电容器连接的微分耦合同步 Regular Papers

Yu-meng XU, Zhao YAO, Aatef HOBINY, Jun MA

《信息与电子工程前沿(英文)》 2019年 第20卷 第4期   页码 571-583 doi: 10.1631/FITEE.1800499

摘要: 非线性振子和电路常用于研究耦合同步和一致性问题。完全同步是指所有振子保持相同幅度和相位,主要发生在完全相同振子之间。相位同步是指振子保持步调节律同步而幅度不同。对于无维动力学系统和振子,同步依赖于耦合变量的选择和耦合方式。非线性电路中电阻常用于连接两个或以上电路,触发电压耦合可对耦合电路反馈调制。本文采用电容器耦合两个Pikovsk-Rabinovich(PR)电路,这种电场耦合机制为微分耦合提供了依据。讨论了对称性和错位耦合下两个混沌电路的同步稳定性问题。在电阻耦合下,两个混沌电路容易完全同步。进一步讨论电容器耦合,发现当耦合电容器选择合适电容值时,两个耦合电路同步可被有效控制,且耦合电容器能量流有助于对同步的调控。混沌电路的同步实现和耦合通道有关,如对称性耦合容易完全同步,错位耦合有利于相位同步。电容器对应电场耦合能降低耦合器件能量(焦耳热)消耗,加强两个耦合电路能量输运和交换,从而实现混沌电路同步。

关键词: 同步;电压耦合;混沌电路;电容器耦合    

A redundantly actuated PRPRP radial mechanism in the segment erector of a shield machine for synchronization

Wanghui BU, Zhenyu LIU, Jianrong TAN, Jin CHENG

《机械工程前沿(英文)》 2011年 第6卷 第4期   页码 463-467 doi: 10.1007/s11465-011-0225-z

摘要:

The shield machine is a heavy construction machine for tunnel excavation, and the segment erector is an important subsystem of the shield machine. It is difficult to achieve precise control in the 6-DOF (degree of freedom) erector in the 2-DOF 5-bar radial mechanism. Hence, this paper proposes a redundantly actuated PRPRP radial mechanism for the segment erector. When the redundant actuator is unlocked, the radial mechanism is able to adjust its posture, which has two degrees of freedom. On the other hand, when the redundant actuator is locked or produces enough pre-tightening tensile force, the PRPRP mechanism can ensure the synchronization of the two driving hydraulic cylinders along the radial direction based on the mechanical structure, which has one degree of freedom. The redundant actuator also facilitates the equal application of two flexural torques at the hydraulic cylinders; thus, preventing the overload of a single cylinder.

关键词: redundant actuation     parallel mechanisms     five-bar mechanisms     segment erectors     shield machines    

Integrating space and time: a case for phenological context in grazing studies and management

Dawn M. BROWNING, Sheri SPIEGAL, Richard E. ESTELL, Andres F. CIBILS, Raul H. PEINETTI

《农业科学与工程前沿(英文)》 2018年 第5卷 第1期   页码 44-56 doi: 10.15302/J-FASE-2017193

摘要: In water-limited landscapes, patterns in primary production are highly variable across space and time. Livestock grazing is a common agricultural practice worldwide and a concern is localized overuse of specific pasture resources that can exacerbate grass losses and soil erosion. On a research ranch in New Mexico with average annual rainfall of 217 mm, we demonstrate with a quantitative approach that annual seasons vary greatly and examine foraging patterns in Angus-Hereford ( ) cows. We define five seasonal stages based on MODIS NDVI: pre-greenup, greenup, peak green, drydown and dormant, and examine livestock movements in 2008. Daily distance traveled by cows was greater and foraging area expanded during periods with higher precipitation. A regression model including minimum NDVI, rainfall and their interaction explained 81% of the seasonal variation in distance traveled by cows ( <0.01). Cows explored about 81 ha·d while foraging, but tended to explore smaller areas as the pasture became greener (greenup and peak green stages). Cows foraged an average of 9.7 h daily and spent more time foraging with more concentrated search patterns as pastures became greener. Our findings suggest that phenological context can expand the capacity to compare and integrate findings, and facilitate meta-analyses of grazing studies conducted at different locations and times of year.

关键词: GPS collars     Jornada Experimental Range     land-surface phenology     livestock movement     LTAR     MODIS NDVI     rangeland    

Cell-free systems in the new age of synthetic biology

Fernando Villarreal,Cheemeng Tan

《化学科学与工程前沿(英文)》 2017年 第11卷 第1期   页码 58-65 doi: 10.1007/s11705-017-1610-x

摘要: The advent of synthetic biology has ushered in new applications of cell-free transcription-translation systems. These cell-free systems are reconstituted using cellular proteins, and are amenable to modular control of their composition. Here, we discuss the historical advancement of cell-free systems, as well as their new applications in the rapid design of synthetic genetic circuits and components, directed evolution of biomolecules, diagnosis of infectious diseases, and synthesis of vaccines. Finally, we present our vision on the future direction of cell-free synthetic biology.

关键词: cell-free system     application    

神经元之间的相位同步和能量平衡 Research Article

谢盈1,姚昭1,马军1,2

《信息与电子工程前沿(英文)》 2022年 第23卷 第9期   页码 1407-1420 doi: 10.1631/FITEE.2100563

摘要: 在一类简单的神经元电路不同支路嵌入光电管和热敏电阻来设计一种功能性神经元。通过光电管的光电流和流经热敏电阻的通道电流可以控制神经元电路的场能量。神经元的放电模态同时依赖于外界光照和温度。在不同的光照和温度刺激下,两个功能神经元存在能量差。因此,在场能量传递和交换过程中神经元之间开始建立突触连接并相互耦合。我们提出两种规则来讨论神经元之间突触耦合增强问题,神经元之间的能量差控制着神经元之间突触耦合强度的增长和突触电流变化,且神经元之间的同步有利于维持神经元之间的能量平衡。第一类规则类似于饱和增益法,即神经元在达到完全同步之前其突触耦合强度以恒定的增益周期性增长。第二类规则指出神经元突触耦合强度以恰当的增益呈现指数型增长,直到神经元之间达到能量平衡。两个不同的神经元在突触耦合增强的过程中可以实现相位同步。两个完全相同的神经元即使在噪声环境下,神经元耦合突触按照第二类规则增长强度依旧可以有效实现完全同步和能量平衡。此结果表明神经元突触更倾向于以指数型方式来增长其耦合强度。这些研究结果有助于揭示外界刺激如何唤醒和激活神经元之间的突触连接,进一步理解突触耦合电流时变的特性。潜在的生物物理机制在于外界差异性的刺激打破了神经元之间的能量平衡,因此突触耦合不断被增强来实现神经元之间能量动态平衡。这些研究结果为设计和训练智能神经元电路提供了思路,即通过设置梯度性能量分布来调控耦合通道。

关键词: 哈密顿能量;耦合同步;突触增强;神经元电路    

NEW ZEALAND DAIRY FARM SYSTEMS AND KEY ENVIRONMENTAL EFFECTS

Jiafa LUO, Stewart LEDGARD

《农业科学与工程前沿(英文)》 2021年 第8卷 第1期   页码 148-158 doi: 10.15302/J-FASE-2020372

摘要: This paper provides an overview of the range of dairy pasture grazing systems used in New Zealand (NZ), the changes with increased inputs over time and associated key environmental effects including nitrogen (N) leaching and greenhouse gas (GHG) emissions. NZ dairy farming systems are based on year-round grazing and seasonal milk production on perennial ryegrass/clover pasture where cows are rotationally grazed in paddocks. There was an increase in stocking rate on NZ dairy farms from 2.62 cows ha in 2000/2001 to 2.85 cows ha in 2015/2016. During the same period annual milk solids production increased from 315 to 378 kg·yr per cow. This performance has coincided with an increase in N fertilizer use (by 30%) and a twofold increase in externally-sourced feeds. Externally-sourced feeds with a low protein concentration (e.g., maize silage) can increase the efficiency of N utilization and potentially reduce N losses per unit of production. Off-paddock facilities (such as standoff or feed pads) are often used to restrict grazing during very wet winter conditions. A systems analysis of contrasting dairy farms in Waikato (largest NZ dairying region) indicates that the increased input would result in an increase in per-cow milk production but little change in efficiency of milk production from a total land use perspective. This analysis also shows that the increased inputs caused an 11% decrease in N footprint (i.e., N emissions per unit of milk production) and a 2% increase in C footprint (i.e., greenhouse gas (GHG) emissions per unit of milk production).

关键词: dairy farms     environmental impacts     grazing systems     intensification     mitigation    

利用勒让德多项式同步两种不同的混沌系统及其在安全通信中的应用 None

Saeed KHORASHADIZADEH, Mohammad-Hassan MAJIDI

《信息与电子工程前沿(英文)》 2018年 第19卷 第9期   页码 1180-1190 doi: 10.1631/FITEE.1601814

摘要: 提出一种新的由状态反馈控制器和鲁棒控制项组成的混沌同步控制器,采用勒让德多项式补偿不确定性,还考虑截断错误。由于正交函数定理,勒让德多项式可逼近任意小的近似误差的非线性函数。因此,勒让德多项式可取代模糊系统和神经网络来估计和补偿控制系统中的不确定性。勒让德多项式具有比模糊系统和神经网络更少的调整参数,它的调整过程更为简单。与模糊系统的参数类似,使用从稳定性分析获得的自适应规则在线估计勒让德系数。假设主系统和从系统分别是Lorenz混沌系统和Chen混沌系统。安全通信系统需要基于观测器同步,因为主系统通过信道只发送一个状态变量。讨论了使用基于观测器同步获得其他状态变量的方法。仿真结果表明该方法的有效性。与模糊滑模控制器的比较表明,所提的控制器表现出优异的瞬态响应。此外,解释了安全通信问题,并测试了安全通信中控制器的性能。

关键词: 基于观测器同步;混沌系统;勒让德多项式;安全通信    

潜在用于单侧膝受伤患者的传感引导步态同步下肢外骨骼 Research Articles

王东海1,2

《信息与电子工程前沿(英文)》 2022年 第23卷 第6期   页码 920-936 doi: 10.1631/FITEE.2000465

摘要:

本文展示了一种可潜在帮助单侧膝受伤患者正常行走的传感引导步态同步下肢外骨骼系统。外骨骼能够减轻人体体重对受伤膝下肢的负载,并维持与健康侧下肢行走步态摆动相同步。传感引导步态同步系统集成了人体传感网络,它能感知健康侧下肢的运动步态。基于测量的关节角度轨迹引导,安装电机的髋关节在行走中提起腿杆,并将膝受伤步态和健康步态以半周期延时进行同步。实验验证了下肢外骨骼的效果。本文比较了健康腿和膝受伤腿的测量关节角度轨迹、仿真的膝受力、人机交互力等方面,结果说明髋关节安装电机受控制的下肢外骨骼能够将受伤腿和体重支撑外骨骼的融合步态与健康腿步态进行同步。

关键词: 传感引导;下肢外骨骼;人体传感网络;步态同步;体重支撑    

Recent advances in cycloaddition of CO with epoxides: halogen-free catalysis and mechanistic insights

《化学科学与工程前沿(英文)》 2023年 第17卷 第12期   页码 1879-1894 doi: 10.1007/s11705-023-2354-4

摘要: The atom-economical cycloaddition of CO2 with epoxides to synthesize cyclic carbonates is a promising route for valuable utilization of CO2. Halogenide such as alkali metal halides and quaternary ammonium salt have been developed as the efficient catalysts. However, the spilled halogen causes equipment corrosion and affects the product purity. To address these concerns, the halogen-free cycloaddition of CO2 with epoxides has always been desired. In this review, we systematically discussed the halogen-free catalysis for cycloaddition of CO2 with epoxides from the mechanistic insights, aiming to promote the development of efficient halogen-free catalysts. Two types of catalysts, i.e., alternatives of halogen nucleophiles for epoxide activation, and bifunctional catalysts with Lewis acid-base sites for synergistic activation of CO2 and epoxides are summarized and emphasized. Specially, metal oxides as the potential halogen-free catalysts are highlighted due to their flexible acid-base sites for synergistic activation of CO2 and epoxides, facile preparation, and low cost.

关键词: carbon dioxide     halogen-free catalysis     cyclic carbonate     mechanistic insight    

Hollow carbon spheres and their noble metal-free hybrids in catalysis

《化学科学与工程前沿(英文)》 2021年 第15卷 第6期   页码 1380-1407 doi: 10.1007/s11705-021-2097-z

摘要: Hollow carbon spheres have garnered great interest owing to their high surface area, large surface-to-volume ratio and reduced transmission lengths. Herein, we overview hollow carbon sphere-based materials and their noble metal-free hybrids in catalysis. Firstly, we summarize the key fabrication techniques for various kinds of hollow carbon spheres, with a particular emphasis on controlling pore structure and surface morphology, and then heterogeneous doping as well as their metal-free/containing hybrids are presented; next, possible applications for non-noble metal/hollow carbon sphere hybrids in the area of energy-related catalysis, including oxygen reduction reaction, hydrogen evolution reaction, oxygen evolution reaction, water splitting, rechargeable Zn-air batteries and pollutant degradation are discussed; finally, we introduce the various challenges and opportunities offered by hollow carbon spheres from the perspective of synthesis and catalysis.

关键词: hollow carbon spheres     functionalization     noble metal-free     catalysis    

标题 作者 时间 类型 操作

The ecological adaptability of cloned sheep to free-grazing in the Tengger Desert of Inner Mongolia,

Xinxin LI,Huijuan WANG,Guanghua SU,Zhuying WEI,Chunling BAI,Wuni-MENGHE,Yanhui HOU,Changqing YU,Shorgan BOU,Guangpeng LI

期刊论文

Error analysis of the parameters for non-coaxial grazing X-ray microscope

ZHAO Lingling, HU Jiasheng, LI Xiang

期刊论文

导航卫星双向伪距时间同步

谭述森

期刊论文

具有任意有限延迟耦合布尔网络的完全同步

Jie LIU, Lulu LI, HabibM. FARDOUN

期刊论文

我国草原生产力

侯扶江,王春梅,娄珊宁,侯向阳,呼天明

期刊论文

基于混沌电路电容器连接的微分耦合同步

Yu-meng XU, Zhao YAO, Aatef HOBINY, Jun MA

期刊论文

A redundantly actuated PRPRP radial mechanism in the segment erector of a shield machine for synchronization

Wanghui BU, Zhenyu LIU, Jianrong TAN, Jin CHENG

期刊论文

Integrating space and time: a case for phenological context in grazing studies and management

Dawn M. BROWNING, Sheri SPIEGAL, Richard E. ESTELL, Andres F. CIBILS, Raul H. PEINETTI

期刊论文

Cell-free systems in the new age of synthetic biology

Fernando Villarreal,Cheemeng Tan

期刊论文

神经元之间的相位同步和能量平衡

谢盈1,姚昭1,马军1,2

期刊论文

NEW ZEALAND DAIRY FARM SYSTEMS AND KEY ENVIRONMENTAL EFFECTS

Jiafa LUO, Stewart LEDGARD

期刊论文

利用勒让德多项式同步两种不同的混沌系统及其在安全通信中的应用

Saeed KHORASHADIZADEH, Mohammad-Hassan MAJIDI

期刊论文

潜在用于单侧膝受伤患者的传感引导步态同步下肢外骨骼

王东海1,2

期刊论文

Recent advances in cycloaddition of CO with epoxides: halogen-free catalysis and mechanistic insights

期刊论文

Hollow carbon spheres and their noble metal-free hybrids in catalysis

期刊论文