Demonstration and Radiation Extension mode of Agricultural Technology——A Case of the Science and Technology Project of High Yield in Hebei Province

Firstly,relying on the science and technology project of high yield in Hebei Province,connotation of agricultural technology demonstration and extension mode and the high yield grain project in Hebei Province is introduced.Extension mode of agricultural technology demonstration and radiation is constructed.Agricultural technology demonstration and radiation mode includes the radiation center,primary irradiation and secondary irradiation.Secondly,management system and operational mechanism of agricultural technology demonstration and radiation mode are discussed,mainly expressed in establishing leading group in each demonstration county(city),carrying out leader contract responsibility system,establishing expert advisor steering group and setting up core experts group for subject,establishing technical experts group for subject,setting up leading group in the radiation area,carrying out chief expert responsibility system and technician matrix responsibility system,establishing the operating mechanism of "open,flow,competition and collaboration" with "test area-expert two-way selection" as the core content.Finally,countermeasures to improve the agricultural technology demonstration and radiation mode is put forward,such as establishing the rural technology demonstration base,strengthening cooperation with enterprises,and adopting flexible technical training,so as to promote the spread of agricultural high-tech,to increase the contribution rate of agricultural technology,and to offer ideas for agricultural technology extension model at the new era.

Properties study of LiNbO_3 lateral field excited device working on thickness extension mode

This paper investigates the properties of thickness extension mode excited by lateral electric field on LiNbO3 by using the extended Christoffel-Bechmann method. It finds that the lateral field excitation coupling factor for amode （quasi-extensional mode） reaches its maximum value of 28% on Xmcut LiNbO3. The characteristics of a lateral field excitation device made of X-cut LiNbO3 have been investigated and the lateral field excitation device is used for the design of a high frequency ultrasonic transducer. The time and frequency domain pulse/echo response of the LiNbO3 lateral field excitation ultrasonic transducer is analysed with the modified Krimholtz-Leedom-Matthae model and tested using traditional pulse/echo method. A LiNbO3 lateral field excitation ultrasonic transducer with the centre frequency of 33.44 MHz and the -6 dB bandwidth of 33.8% is acquired, which is in good agreement with the results of the Krimholtz-Leedom-Matthae model. Further analysis suggests that the LiNbO3 lateral field excitation device has great potential in the design of broadband high frequency ultrasonic transducers.

伸展区域平衡剖面法及其在构造分析中的应用

从伸展构造样式出发 ,针对不同的地质模型提出了不同的数学模型作为平衡剖面恢复实现的基础。“多米诺”骨牌模型采用刚体平移、旋转实现恢复 ;伸展断层转折褶皱模型采用剪切法恢复 ,也有用等岩层长度法作构造恢复。通过淮阜凹陷实际地质剖面的恢复 ,数学模型以正演、反演两种角度便捷的实现构造平衡 ,恢复控凹断层发育期次 ;

南海北部陆缘地壳结构及其伸展破裂过程的差异性

系统分析了南海北部地壳岩石圈结构及其新生代伸展变形的差异性,并探讨了其成因机制。基于南海北部陆缘重磁震联合反演所获得的Moho面深度和地壳厚度,发现地壳的伸展薄化具有“南北分带、东西分段”差异,由北向南可分为陆架均匀薄化带(地壳伸展系数β<1.2)、上陆坡楔形薄化带(1.2<β<2)、下陆坡强烈薄化带(β>2)共3个带;而陆缘深水区由东向西以4条NW-SE向基底隐伏断裂带为界可分为5段:台西南盆地陆缘,珠江口盆地陆缘的东段陆缘、中段陆缘、西段陆缘,琼东南盆地陆缘。不同区段地壳薄化程度交替变化,强烈薄化区呈指状向陆延伸,其所对应的沉积盆地断裂样式、充填结构、裂后沉降、岩浆活动等均表现出不同特征。上述差异表明,南海北部陆缘岩石圈在新生代的伸展薄化过程中,显著受控于先存中生代主动陆缘所形成的基底构造格局及其所对应的岩石圈结构差异;在伸展过程中岩浆大量底侵至下地壳,其热效应导致下地壳的韧性增强,进而改变地壳薄化方式,而先存NE-SW向走滑断裂成为伸展过程中岩浆大量底侵至下地壳的通道。依据岩石圈结构差异及其与沉积盆地响应关系,可将南海北部陆缘岩石圈伸展破裂过程总结为自上而下伸展破裂模式、自下而上伸展破裂模式、似纯剪切快速伸展破裂模式共3种模式。不同伸展破裂模式下,其所对应的裂陷期沉积盆地规模、岩浆改造程度均具有明显差异,导致勘探潜力及勘探策略的不同。

可拓物元模型在银行经营目标优度综合评价中的应用研究

文章根据物元学中的可拓数学方法与关联函数理论,遵循银行经营的安全性、流动性、盈利性的"三性"原则,建立了银行经营目标优度综合评价的可拓物元模型.实例研究表明:该模型概念清晰、定义明确、计算简便、评价客观、结论可靠,不失为银行经营目标优度综合评价的一种新方法.但是,由于可拓物元模型在银行经营目标评价中的应用尚处于初试阶段,因此,还有诸如指标的选择、量值范围的界定、指标权重的赋值等问题需要作进一步的探讨.

An accurate modeling of piezoelectric smart beams with first-order shear deformation theory

A finite element model for piezoelectric smart beam in extension mode based on First-order Shear Deformation Theory(FSDT)with an appropriate through-thickness distribution of electric potential is presented.Accuracy of piezoelectric finite element formulations depends on the selection of assumed mechanical and electrical fields.Most of the conventional FSDT-based piezoelectric beam formulations available in the literature use linear through-thickness distribution of electric potential which is actually nonlinear.Here,a novel quadratic profile of the through-thickness electric potential is proposed to include the nonlinear effects.The results obtained show that the accuracy of conventional formulations with linear through-thickness potential approximation is affected by the material configuration,especially when the piezoelectric material dominates the beam cross section.It is shown that the present formulation gives the same level of accuracy for all regimes of material configurations in the beam cross section.Also,a modified form of the FSDT displacements is employed,which utilizes the shear angle as a degree of freedom instead of section rotation.Such a FSDT displacement field shows improved performance compared to the conventional field.The present formulation is validated by comparing the results with ANSYS 2D simulation.The comparison of results proves the improved efficiency and accuracy of the present formulation over the conventional formulations.

Tracking Control of a Class of Differential Inclusion Systems via Sliding Mode Technique

The tracking problem for a class of differential inclusion systems is investigated. Using global sliding mode control approach, a tracking control is proposed such that the output of a differential inclusion system tracks the desired trajectory asymptotically.An extensive reaching law is proposed to achieve the chattering reduction. Finally, an example is given to illustrate the validity of the proposed design.

The electromechanical features of LiNbO_(3) crystal for potential high temperature piezoelectric applications

Lithium niobate(LiNbO_(3),LN)crystal is a multi-functional material with favorable piezoelectric,nonlinear optical and electro-optic properties.In this study,the electromechanical properties of the radial extensional(RE)and the thickness extensional(TE)modes of the congruent LN are studied and the temperature dependent behaviors are revealed.The RE mode electromechanical coupling factors(kp)for the Y-and Z-oriented discs are calculated and found to be 3.8%and 24.7%,respectively,which are nearly the same as the experimental results of 3.8%and 25.2%,respectively.The maximum RE and thickness shear(TS)modes electromechanical coupling factors are obtained to be 47.6%and 68.5%for the Yx/25
and Yx/167
crystal cuts,respectively.The LN crystal possesses good temperature stability of the electromechanical coupling factors(RE and TE modes)from 20℃ to 500℃,where the variations of kp and kt for the Y-oriented discs are<8.0%and<1.8%,respectively.