主要动力

This article on the important impetus for the smart battery charger hardware design and implementation.

本文主要研究重要的动力来源蓄电池的智能充电器硬件设计与实现。

Along with energy crisis and worsened environment becoming more and more intensively, gas-vehicle receives the unprecedented recognition because of its less emissions, more economical and saving petroleum resource. The research and utilization of gas-vehicle develop quickly all over world. Of course, automotive fuel changing from gasoline and diesel into gas fuel is also carried out blazingly everywhere in our country.

中文题名燃气汽车发动机燃烧特性及工作性能研究副题名外文题名 Study on combustion characteristics and performances of automotive engine by gas fuel 论文作者詹樟松导师夏来庆教授学科专业动力机械及工程研究领域\研究方向学位级别博士学位授予单位浙江大学学位授予日期2001 论文页码总数132页关键词汽车发动机燃气汽车发动机燃烧馆藏号BSLW /2001 /U464 /32 随着能源危机和生态恶化日益严重，燃气（主要指压缩天然气和液化石油气）汽车以其优良的排放、良好的经济性以及能够部分替代紧张的石油资源而受到了空前重视，世界范围内燃气汽车的研究和应用也随之空前高涨。

The main purpose of this paper is to research the modal of coal blend optimization.

动力配煤优化模型的研究及实现是本文的主要研究内容。

In Chapter 3,the applications of boundary value problem to the system with Allee effect and impulsive effect are given.

第3章主要讨论了边值问题在具有Allee效应单种群生物动力系统中的应用。

The seed discharging mechanism for seeding-tray precision seeding device with Brush Wheel is designed,composed with seed pitching apparatus and drive gearing .

设计了适合于刷轮式苗盘精播装置的强制排种机构。此机构主要由投种器、传动系统和动力机构组成。

In the new century, human resource development and human capital accumulation become decision of social economic development.

在新世纪，人力资源开发，人力资本积累将成为一个国家社会经济发展的最主要的动力源泉。

Cavitation is one of the main reasons for accidents and destroys in power system.

空穴现象是引起动力系统事故的主要现象之一。

The obstacles to this liberalisation lie largely at national level, although the EU's Lisbon Agenda—the self-imposed measures needed to make Europe "the most dynamic and competitive knowledge-based economy in the world" by 2010—can help to chivvy governments along.

市场解放的障碍主要来自国家，尽管欧盟的里斯本议程——到2010年使欧洲成为"世界上最具动力和竞争力的知识经济体"的自愿措施——能够减少国家干预。

1Niche construction can lead to stable coexistence of diverse genotypes in spatially structured population, which supports a stable polymorphism even without heterozygote superiority.(2)With habitat deterioration, niche construction accelerates the formation of steady polymorphism and hence impedes the harmful influences of environment on the population, which might embody a life-history strategy of organism under the unfavorable environment.(3)Niche construction results in the coexistence with alternative polymorphism through genotype-environment feedback and limited gene flow.(4)The niche-constructing organism is an active force to alter its environment and hence the direction of natural selection in order to better survival.(5)Spatial dynamics and distribution pattern of metapopulation are profoundly influenced by time-lagged niche construction.(6)Metapopulation size can reach a fixed level in the recency effect and equal weighting of time lag but is statistical stability in primacy effect, which implies the primacy effect is most remarkable.(7)The increment in the relative weightingof each generation\' niche construction and the length of time lag are significant factors for system destabilization.(8)Moderate capacity of positive niche construction benefits the metapopulation persistence.(9)The narrowing of niche breadth can decrease the metapopulation size and thereby increase the extinction risk.(10)The coupled function of time lag and niche construction make the system oscillation and generate the spiral wave, spiral-broken and circular wave in heterogeneous habitat.The spatial distributions of metapopulation and resource content are complementary due to a phase lag of their both frequencies.(12)Metapopulation persistence with niche construction depends not only on the balance between colonization and extinction, but also on the balance between the ability of niche construction and natural dissipation of habitat.(13)Metapopula-tion can survive under certain condition when the percent of suitable patches in habitat is lower than the ration of extinction to colonization.(14)Two thresholds exist in the process of transition of habitat quality dynamics from unsuitable to suitable, which include the intensity of niche construction and the initial condition of system.(15)Metapopulation size is positive correlated with the ability of positive niche construction, which means that organism or population who has strongly positive influences on their environment plays an important role to maintain the available habitat.

通过上述几个方面的研究，主要得出以下15条结论：(1)生态位构建可使空间结构种群，甚至是在没有杂合子优势的条件下，形成多种可能的稳定基因型分布模式；(2)随着环境的破坏与恶化，种群的生态位构建作用加速其较早形成稳定多态以阻碍环境对种群的不利影响，解释了有机体在不利环境下的一种生活史对策；(3)生态位构建作用通过基因型—环境反馈机制及有限的基因交流导致基因型多态的稳定共存；(4)有机体的生态位构建作用是一种积极的动力改变环境进而改变其自然选择的方向；(5)生态位构建的时滞作用对集合种群动态和空间分布产生深刻影响；(6)集合种群大小在时滞的崭新效应和等权重效应下达到一固定值，而在首位效应下达到统计稳定，表明首位效应的影响最显著；(7)首位效应下生态位构建相对权重的增量和时滞的长度是影响系统不稳定性动态的关键因素；(8)适中的生态位构建强度有利于集合种群的续存；(9)生态位宽度变窄会减少集合种群的数量从而增加其灭绝风险；(10)时滞和生态位构建的双重作用使系统产生周期振荡，并在异质性环境中产生稳定的螺旋波，破碎的螺旋波和环形波三种分布模式；(11)集合种群与资源含量的空间分布因为相滞而互补；(12)具有生态位构建的集合种群续存不仅取决于侵占率与灭绝率之间的平衡，而且依赖于生态位构建能力同其生境的自然消耗速率之间的妥协；(13)当生境中适合侵占的斑块比例小于其侵占率与灭绝率之比时，生态位构建作用促使集合种群在一定条件下续存：(14)生境斑块的状态从不适合到适合转变过程中存在生态位构建强度和系统初始条件这两个阈值；(15)集合种群的大小同正生态位构建能力正相关，意味着对环境具有较强正作用的有机体对维持有效生境起积极作用。

Based on the working condition of the tractor, a new type of electric tractor drive system which combines a motor and a gear, and the evaluation index and the calculation method for dynamic performance of electric tractor are suggested; taking an electric tractor drive system as design object, the balance graph of drive-resistance force, climbable gradient under different shifts, and continuous working time are calculation analyzed.

根据电动拖拉机作业特点，提出了一种电动机和变速箱相结合的电动拖拉机传动系统结构方案，并给出了电动拖拉机动力性能和经济性能评价指标以及电驱动系统主要参数的设计计算方法，以基于串励直流电动机的某型号小四轮电动拖拉机电驱动系统为设计实例，计算分析了该电动拖拉机的驱动力-行驶阻力平衡图、不同挡位下的爬坡度以及连续作业时间。

According to the clear water experiment, aeration performance of the new equipment is good with high total oxygen transfer coefficient and oxygen utilization ratio.

曝气设备的动力效率在叶轮转速为120rpm～150rpm时取得最大值，此时氧利用率和充氧能力也具有较高值。

The environmental stability of that world - including its crushing pressures and icy darkness - means that some of its most famous inhabitants have survived for eons as evolutionary throwbacks, their bodies undergoing little change.

稳定的海底环境─包括能把人压扁的压力和冰冷的黑暗─意谓海底某些最知名的栖居生物已以演化返祖的样态活了万世，形体几无变化。