不同程度水分处理对烟农21根系抗旱特性的影响

此文在盆栽条件下研究了不同程度干旱胁迫对冬小麦根系抗旱特性的影响。结果表明：中度和严重水分胁迫条件下,单株根干重、根冠比和次生根数目增加,但冠干重降低,且烟农21根干重、冠干重、次生根数目均高于鲁麦21,说明烟农21根系形态抗旱性优于鲁麦21。中度水分胁迫和严重水分胁迫条件下,烟农21和鲁麦21根系活力均降低;各生育时期根系活力差异显著,拔节期>挑旗期>开花期>成熟期;烟农21根系活力降低幅度明显低于鲁麦21。中度和严重水分胁迫下,烟农21根系可溶性糖含量分别提高了32.8%、65.6%,脯氨酸含量分别提高了327%和514%。水分胁迫提高了两品种根系的超氧化物岐化酶（SOD）活性、过氧化物酶（POD）活性和丙二醛（MDA）含量。各生育期根系SOD、POD酶活性比较,开花期>挑旗期>拔节期>成熟期。说明烟农21抗旱性优于鲁麦21。     

预处理对食物蛋白酶解特性影响的研究进展

为了提高食物蛋白利用率,更好的发挥其酶解特性,可以在酶解前对蛋白进行预处理。综述了国内外学者提出的预处理的方法和相应机理。     

重金属铅镉对甜高粱生长的影响及其积累特性研究

旨在为甜高粱在修复土壤重金属污染领域的应用提供理论支撑。以甜高粱品种‘辽甜1 号’为供试材料,采用土壤盆栽试验研究不同浓度铅、镉及其复合污染作用下甜高粱的生长响应及重金属吸收、富集和迁移特征变化。结果表明：低浓度Pb(≤100 mg/kg)、Cd(≤1 mg/kg)处理促进了甜高粱的生长,高浓度Pb(≥1000 mg/kg)、Cd(≥10 mg/kg)则呈现出抑制效应,根长、株高、穗长和生物量均显著减小。甜高粱各部位重金属含量随着土壤Pb、Cd处理浓度的升高而增加,其中重金属Pb的含量大小顺序为根＞叶＞茎＞穗,重金属Cd的含量大小顺序为根＞茎＞叶＞穗,且甜高粱对Cd的富集系数和转运系数均显著高于Pb。由此可知,甜高粱品种‘辽甜1 号’对重金属Pb、Cd具有较强的抗逆性和较好的吸收积累和转运能力,其在Pb、Cd单一及其复合污染土壤修复方面具有潜在的应用价值。     

不同硝态氮含量的硝基复合肥对玉米苗期生长及光合特性的影响

为了研究硝基复合肥中硝态氮所占比例对玉米苗期生长及光合特性的影响,通过温室盆栽试验,以玉米植株性状、叶片光合色素含量及光合特性为评价参数,对硝态氮含量不同的硝基复合肥进行肥效评价。结果表明,随着硝基复合肥中硝态氮所占比例的增加,玉米的株高、茎粗、叶面积、叶片光合色素含量、光合速率、地上部和地下部干物质量均有不同程度的提高。硝基复合肥中硝态氮的含量为4%时,其玉米植株农艺性状、光合色素含量、光合强度及干物质量均显著高于硝态氮含量为2%的硝基复合肥,且与硝态氮含量为6%的硝基复合肥相比上述指标无显著差异。综合考虑,硝基复合肥中硝态氮的含量为4%即可较好的满足玉米生长发育需要。     

不同处理方法对白壳薏苡种子发芽特性的影响

以黔西南州普遍种植的白壳薏苡为材料,探讨不同种子处理方法对白壳薏苡种子发芽特性的影响.结果表明,白壳薏苡最适发芽温度为30℃,去壳处理发芽率高于未去壳处理;大于6 mm粒径的发芽率最高为85％;变温处理25℃8 h/35℃16h条件下发芽率最高为90％;其发芽率与出苗率无明显相关,发芽率与成苗率呈显著正相关,出苗率与成苗率呈极显著正相关.     

液态有机肥对滴灌棉花光合特性及产量形成规律的影响

为优化滴灌棉花的施肥技术,探究液态有机肥对滴灌棉花生长发育的影响,笔者采取单因子随机区组试验设计,研究在滴灌棉花不同生育时期施用液态有机肥对棉花光和特性、干物质积累及产量的影响。结果表明:(1)施用液态有机肥能够促进植株生长发育,增大光合速率增加棉花产量,且随着液态有机肥施用量的增大,各处理叶面积指数、SPAD值均呈现先增后减的趋势,均于铃期达最大值,其中苗期与蕾期施液态肥的C处理最大值分别为3.25和62.63;(2)叶片净光合速率(Pn)、蒸腾速率(Tr)、气孔导度(Gs)均以C处理最高,并于8月5日花铃期达到极值,而胞间二氧化碳浓度(Ci)表现为C处理最低,为188.67μmol/mol;(3)整个生育期内单株干物质积累量、伏前桃、伏桃、单株铃数及品质均以C处理最好,与其他处理达显著差异水平(P0.05),且增产幅度为27.01%~42.97%。研究表明,液态有机肥适宜的施用时期不仅可提高叶面积指数、叶绿素含量及光合速率,同时为后期干物质积累及产量的形成奠定基础。     

种植密度对不同叶型大豆近等位基因系物质生产特性的影响

以两对叶型不同的大豆近等位基因系品系为材料,设置4.5,6.0,10.5,15.0,19.5,24.0,28.5万株/hm2的密度处理,研究种植密度对不同叶型近等基因系大豆物质生产特性的影响。结果表明,密度对不同叶型近等基因系叶片叶色值的影响不大,但对叶片光合速率影响较大,尖叶组的净光合速率在低密度(4.5,6.0万株/hm2)和高密度(28.5万株/hm2)条件下较高,而圆叶组净光合速率在较低密度和正常密度(6.0,10.5,15.0万株/hm2)下较高,生育前期种植密度处理对不同叶型大豆的生物产量影响较小,而生育中后期,尖叶组和圆叶组各生育阶段单株生物产量的积累随种植密度的增加呈减小趋势,但最终尖叶组生物产量高于圆叶组。随种植密度增加,尖叶和圆叶组的单株粒数呈逐渐下降趋势。种植密度的变化对尖叶和圆叶组的荚粒数没有一致的规律性的影响,但在不同种植密度下,尖叶组四粒荚数百分比均高于圆叶组,差异达显著水平。从15.0万株/hm2到28.5万株/hm2种植密度下,尖叶组产量随着种植密度增加而逐渐下降,但下降幅度(9.5%)小于圆叶组(16.0%)。总体来说,尖叶组不同密度处理下,仍能有较高的产量表现,可能由于其自身调节功能较强,叶片结构疏朗,有利于通风透光所致。     

槟榔茎秆栽培基质对灵芝营养利用规律及生理特性的影响

本研究从槟榔茎秆主要成分出发,以灵芝为栽培对象,测定不同含量槟榔茎秆粉末对灵芝菌丝体多糖、三萜类物质合成量的影响,测定槟榔茎秆栽培灵芝不同时期生理生化指标并记载生育周期.结果表明,灵芝菌丝中多糖、三萜类物质的含量随槟榔茎干粉末含量的增加而增加,应用槟榔茎干栽培的灵芝生育周期远远小于橡胶木段栽培的灵芝.综合考虑槟榔茎秆的...     

不同施氮方式对花生生理特性及产量的影响

通过氮肥不同施用方式对花生光合性能、酶活性及产量构成因素的影响研究发现,在施纯氮270k岁h耐条件下,缓释尿素(100%基肥)或常规尿素(40%基肥,20%始花期追施,40%开花下针盛期追施)的施用方式,花生净光合速率最大,可达约25mmol/m²·s;同时各生育时期过氧化物酶、可溶性蛋白含量显著高于时照与常规尿素(100%基肥),丙二醛含量显著低于对照与常规尿素(l00%基肥);产量比对照增加9%以上。说明施用缓释尿素或常规尿素(40%基肥,20%始花期追施,40%开花下针盛期追施)的方式对花生光合性能、酶活性及产量提升具有显著效果。     

激素处理对槟榔结果特性及果实内含物的影响

为提高槟榔座果率,并研究果实内含物的变化,本试验以IBA、GA3、云大-120 3种激素对开花期的槟榔进行喷施处理,研究其结果性状与果实内含物的变化规律。结果表明：（1）激素处理明显提高了槟榔结果数及座果率,增大了果型指数,但各激素不同浓度对不同梭上槟榔的结果数、座果率及果型指数作用效果存在明显差异;以GA3 50 mg/L对结果数,IBA 100 mg/L对座果率,IBA 400 mg/L对果型指数提高效果显著。（2）激素处理提高了果实中可溶性糖、蛋白质及纤维素含量,但对淀粉含量作用效果不明显;3种激素以云大-120对果实蛋白质、GA3对可溶性糖、IBA果实中纤维素含量作用效果显著。表明促进生长类激素处理可提高槟榔座果率并改变其内含物的积累量,但不同激素间存在一定差异。     

Dynamic characteristics of multi-stage planetary gear trains in shield machine cutter drive

A purely torsional dynamic model of multi-stage planetary gear trains is developed to investigate the dynamic characteristics of the transmission system in shield machine cutter drive. In the model,phase difference between mesh stiffness and error among each stage caused by different initial mesh positions is considered,and other factors such as component bearing stiffness,time-varying mesh stiffness and error are considered as well. Inherent characteristic analysis shows there are more unique and diverse vibration modes in multi-stage planetary gear trains than in single-stage planetary gear trains. Through dynamic response analysis,time-domain and frequency-domain response of dynamic meshing force of each stage is obtained. As the frequency of exciting force of medium-speed and high-speed stage is in proximity to the natural frequency of the system,harmonic resonance tends to occur,which needs to be paid great attention to. Dynamic factors of each stage are also computed and prepare the ground for the dynamic optimizing design of planetary gear trains.     

Dynamics research of wind turbine gearbox with herringbone planetary gear

Based on the method of gear system dynamics and Lagrange equation, a translational-rotational coupling dynamic model of the herringbone planetary gear sets is built and dynamic analysis is carried out. The analysis results have guiding meanings for the design of herringbone planetary gear transmission system. Herringbone gear is treated as two helical gears in the model, and gear train elastic coupling, load inertia and stagger angle between the left and right helical gears is considered. The load sharing coefficients of the system are obtained through calculation, and the impact of stagger angle and coupling torsional stiffness between the left and the right helical gears on the load sharing characteristic is analyzed. The analysis results show that when stagger angle is π/2, the load sharing coefficients are the best, and coupling torsional stiffness between the left and the right helical gears has litter influence on the load sharing coefficients.     

Gear-bearing coupling dynamics characteristics of wind turbine planetary gear transmission system under variable load

Considering that the transmission system of wind turbine works in complex and changing load environment caused by stochastic wind speed,this paper uses sparse least squares support vector machine(SL-SVM) to simulate wind speed of true wind field,and obtains time-varying wind load caused by stochastic wind speed. The lumped-parameter method is used to develop a dynamic model of planetary gear transmission system of wind turbine coupled with bearing. The model includes the varying wind load,time-vary mesh stiffness of gear pair and time-vary stiffness of rolling element bearing. The numerical method is used to simulate the dynamic performance of planetary gear system of Multibrid Technology Wind Turbine with 1.5 MW rated power. The vibration displacement responses of the transmission system are obtained as well as dynamic meshing force each pair of gear and nonlinear bearing forces. The research can provide a foundation for optimizing dynamic performance and reliable design of gear transmission system of wind generator.     

LCL型CPT系统的参数设计方法及频率特性分析

以金鲳鱼为原料,固定小麦粉与水的质量比为2∶1,食盐添加量2%,微波真空度0.095 MPa,在单因素试验的基础上,通过正交试验对微波真空技术膨化鱼糜饼工艺条件进行优化。结果表明,鱼糜饼制作的最佳工艺条件为:鱼糜含量35%,膨化温度100℃,膨化时间20 min,鱼糜饼厚度2 mm,在该工艺条件下,制得的膨化鱼糜饼色泽金黄、质地酥脆、风味清香,成品膨化率可达到540%。     

Gearing theory and transmission characteristic for dual drive planetary transmission system with large capacity of shield machine

On the basis of studying shield machine and planetary transmission, to address cutting drive system of shield machine, a novel dual drive planetary transmission system with large capacity is presented, and its principle and structure are analyzed. Through establishing a new kinematical model of the transmission system and analyzing its characteristics, the transmission ratio, rev and torque relationship and changing rules within the system are acquired. By comparing the simplified experimental results with theoretical results,it is shown that the variation is basically the same, which verifies the correctness of the model and analysis method. The high-power dual-driven planetary gear transmission system with great transmission ratio, strong carrying capacity, can perform the function of low-speed and high-torque output, and meet basic requirements of shield machine. It can not only replace the traditional multi-driven transmission system, but also achieve the transmission function in three different types of shield machine.     

渐变刚度钢板弹簧建模方法对比

为更好地分析钢板弹簧刚度特性,对钢板弹簧建模方法进行了对比研究。依据钢板弹簧国家标准GB/T 19844-2005,针对某型渐变刚度钢板弹簧分别在有限元软件Hypermesh和多体动力学软件Adams中建立其有限元模型和离散梁模型,并进行了仿真,得到刚度特性。将仿真结果与试验值进行了比较。结果表明,在针对该钢板弹簧的刚度分析中,运用离散梁法得到的刚度特性更加接近试验值。     

Stability of a nonlinear red tide dynamic model in a polluted environment

We develop a nonlinear red tide dynamic model to study the effect on a system of two harmful phytoplankton and zooplankton and of a toxicant emitted into the environment from external sources and a toxin excreted by phytoplankton. We use modern nonlinear dynamics to discuss stability and bifurcation, and obtain the thresholds of persistence and extinction for each species. Numerical simulations are used to validate the theoretical results. The results show that a sequence of Hopf bifurcations occur at the interior equilibrium as the delay increases or the growth rates increase.     

Dynamic simulation of and experimentation with tracked vehicle hydrostatic steering characteristics of zero differential systems of a power shift steering transmission

This research investigated problems influencing tracked vehicles steering dynamic characteristics, such as rolling resistance during straight driving, steering centrifugal resistance, acceleration resistance during straight driving, scratching soil resistance of steering. Based on research about the relationship between the hydraulic steering regulation speed system and its maximum stable work pressure when vehicles have central steering on good roads (such as cement and rural roads), a zero differential hydraulic steering system of power shift steering transmission can ensure that vehicles maintain straight ahead stability through reasonably matching a steering drive system. The test indicates that vehicles have good dynamic characteristics when the work pressure accounted for 60% to 80% of the security work pressure.     

Vibration characteristics of face-gear transmission system with parametric excitation

In order to study the influences of different factors on nonlinear dynamics of face-gear transmission system, a nonlinear dynamic model is presented. This model includes backlash, general transmission error, time-varying meshing stiffness, meshing damping, bearings and external load, etc. Based on numerical analysis theory of nonlinear dynamics, the equations are solved and the bifurcation characteristics with different parameters are obtained. And the calculation results show that increasing the backlash and time-varying meshing stiffness will augment the dynamic load of system, but increasing the mesh damping will reduce the dynamic load effectively.     

电源分配网络阻抗分析及去耦电容优化

高速印制板电源分配网络（power delivery networks,PDN）受电电源端口具有瞬时电流大、目标阻抗小的特点。针对任意形状电源板的阻抗问题,提出一种基于解析式与有限差分法的互补模型,并在此基础上结合粒子群算法实现多个受电电源端口的阻抗优化。通过Matlab仿真,发现互补模型的结果与全波有限元法的基本吻合,计算时间则大幅缩短。测量结果表明,优化后实验板的多个受电电源端口阻抗均满足各自的目标值要求。