二阶时滞差分方程的振动性

二阶时滞差分方程的振动性王向东，石永生（郑州轻工业学院基础课部）（零陵师范学院）关键词时滞差分方程；振动解中图分类号Ｏ１７５．１３；０１７５．７关于时滞微分方程的离散模拟的振动性研究开始于１９８８年Ｌ．Ｈ．Ｅｒｂｅ和Ｏ．Ｇ．Ｌａｄａｓ等人的论文。本文...     

振动筛振动电机安装轴的断裂分析及对策

一种用于物料分选的大型振动筛在使用过程中．其振动电机安装轴易产生疲劳断裂。文中针对振动电机布置在筛体下的结构型式．从振动电机安装轴的受力分析入手，进行了疲劳强度计算．结果表明不能满足疲劳强度要求。由此．对这种大型振动筛的局部结构作了改进设计。     

中立型分段常变量微分方程解的振动性

通过构造差分方程的振动解，研究了一类二阶中立型分段常变量微分方程解的振动性，得到几个振动判据。     

一阶非线性中立型微分方程的振动准则

在特定争件下讨论了一阶非线性中立型的微分方程振动问题，产生了一阶非线性中立型微分方程的振动准则，并用极限理论证明了该振动准则的正确性．     

一类二阶中立型微分方程有界解的振动性

研究具有正负系数的二阶中立型微分方程,建立了方程的有界解振动的一个充要条件以及解的振动性.     

GZR型振动流化床在我厂的应用

目前国内制盐行业中已有少数厂矿选用了振动流化床作干燥湿盐的主体设备．本文翔实地介绍了川东盐厂在振动床应用和改进方面的经验和体会．     

试论离心泵振动的原因及其防治措施

大多数离心泵都因产生振动,未充分发挥其效果,还直接缩短了运行寿命。本文在简述离心泵振动原因的基础上,着重就其防治振动的多方面措施加以详述。１离心泵产生振动的多方面原因１．１ 设计欠佳所引起的振动 离心泵设计上刚性不够、叶轮水力设计考虑不周全、叶轮的静平衡未作严格要求、轴承座结构不佳、基础板不够结实牢靠,是泵产生振动的原因。１．２ 制造质量不高所引起的振动 离心泵制造中所有回转部件的同轴度超差、叶轮和泵轴制造质量粗糙,是泵产生振动的原因。１．３ 安装问题所引起的振动 离心泵安装时基础板未找平找正、泵轴和…     

具有正负系数的中立型微分方程的振动性

本文讨论具有正负系数的中立型微分方程[X(t)-R(t)X(t-r)]'+P(t)X(t-τ)-Q(t)X(t-σ)=0的振动性。我们利用新的技巧获得了该方程所有解振动的新的充分条件,改进了文献中有关结果。研究的方法与所得结果均在一定程度上反映了泛函微分方程结构的变化对其振动性的影响。     

基于MATLAB软件的电磁振动给料系统仿真

分析了电磁振动给料系统的力学模型,通过幅频特性曲线分析了固有频率和激振频率的关系,确定了电磁振动给料系统的工作状态,利用MATLAB软件对系统在有阻尼和无阻尼两种不同的情况下进行振动仿真分析,对在有阻尼振动系统中其动力放大系数、调谐值和阻尼比之间的密切关系进行了研究,确定电磁振动给料系统应设计成在低临界近共振的状态下工作。调谐值的理想取值为Z=0．8～0．95。     

D U R 高速振动斩刀分析

本文分析了进口Ｄ．Ｕ．Ｒ．高速振动斩刀的工作原理、特点及其存在的不足之处。     

氨基酸衍生物和丙酮作混合底物的BZ振荡反应

报道氨基酸衍生物与丙酮作混合底物的ＢＺ类振荡反应－ＫＢｒＯ３／（ＣＨ３Ｏ）３ＣＣＨ（ＮＨ２）ＣＯＯＨ／ＣＨ３ＣＯＣＨ３／ＭｎＳＯ４／Ｈ２ＳＯ４体系振荡反应。给出了典型振荡波形及振荡浓度范围，分析了影响振荡反应的因素及振荡反应的温度效应。说明了丙酮及氨基酸的作用。     

非线性系统的来源及奇异性分析

就变比、饱和、振荡、多值响应、循环、失灵、折叠几种典型情形介绍了非线性系统的来源,并分析了非线性系统不同于线性系统的特征：系统稳定性与初值有关且可能存在多个平衡状态;系统可能产生自激振荡;系统平衡态失稳后可进入混沌态,对非线性系统的研究有助于揭示事物发生与发展的因果关系,非周期定态行为的确定为系统科学的发展作出了重大贡献。     

SnO2主体材料气敏振荡特性的进一步研究

经对以ＳnO2为主体材料的掺杂Ｐd的振荡型气敏元件的实验研究和分析,对其振荡机理获得了进一步的认识：掺杂Ｐd是发生电导振荡的必要条件;高浓度的Ｈ２对振荡的抑制作用;某些气体对元件的振荡特性变能产生影响,而振荡频率的高代取决于气体吸附反应产物的能力;该类型气敏元件在低温或常温下对Ｈ２具有较好的敏感特性。     

Synchronization affector of autonomous short-period-sustained oscillation of Saccharomyces cerevisiae

When the yeast Saccharomyces cerevisiae was grown under aerobic continuous culture, an autonomous shortperiod-sustained oscillation appeared. This oscillation was observed in concentrations of various extracellular and intracellular parameters, such as ethanol, acetate, glycogen, dissolved oxygen and intracellular pH. In this work the synchronization affecter of this oscillation was investigated. Ethanol was found not to be the synchronizer of the oscillation because a pulse of ethanol did not affect the phase or period of the oscillation. The oscillation was dependent on the aeration rate, i.e., the oscillation occurred only between 150 and 600 ml min⁻¹. However, the oxygen concentration did not influence synchronization as an upward shift in the oxygen concentration of the gas flow did not affect the sustainability of the oscillation. On the other hand, synchronization was stopped by an enhanced gas flow rate, keeping dissolved oxygen tension at the oscillatory condition, suggesting that synchronization was caused by a volatile compound in the culture. A stepwise increase in carbon dioxide concentration of the gas flow rate ceased synchronization, yet the oscillation seem to continue in each individual cell. Oscillatory behaviour of intracellular pH and carbon dioxide evolution rate showed a phase difference of 90 degrees. Based on these facts it is postulated that carbon dioxide, through the influence of its dissociation on intracellular pH, could be the synchronization affector of the autonomous short-period-sustained oscillation of S. cerevisiae.     

Ultradian metabolic oscillation of Saccharomyces cerevisiae during aerobic continuous culture: hydrogen sulphide, a population synchronizer, is produced by sulphite reductase

We have reported that the consecutive cyclic production of H(2)S resulted in population synchrony of ultradian metabolic oscillation (Sohn et al., 2000). In order to understand the origin of H(2)S and its nature of periodic production, changes of sulphur compounds concentration and responsible enzymes were investigated. The concentrations of extracellular sulphate, intracellular glutathione and cysteine oscillated during metabolic oscillation but only the oscillation of sulphate concentration was out of phase with H(2)S production. The sulphate concentration in culture directly affected the amplitude and the period of metabolic oscillation: (a) the period of metabolic oscillation shortened from 50 min to 30 min when sulphate concentration in the medium was reduced from 46 mM to 2.5 mM; (b) the metabolic oscillation disappeared under sulphate-depletion conditions and arose again by the addition of sulphate. Pulse injection of sulphite (10 microM) perturbed metabolic oscillation with a burst production of H(2)S, while thiosulphate (up to 500 microM) was without apparent effect. Furthermore, addition of S-adenosyl methionine (100 microM) or azoxybacilin (3 mg/kg) decreased H(2)S production with perturbation of metabolic oscillation. The results presented here suggest that H(2)S, a population synchronizer, is produced by sulphite reductase in the sulphate assimilation pathway, and dynamic regulation of sulphate uptake plays an important role in ultradian metabolic oscillation.     

2弹性板自振荡运动的虚拟区域法直接数值模拟

采用分布式拉格朗日乘子/虚拟区域法(DLM/FD)对2弹性板在均匀来流中的自振荡运动进行了直接数值模拟。在合适的系统参数下,增大2板间距或雷诺数,2弹性板从同相位振荡跃迁到反相位振荡;随着剪切模量的增加,弹性板最初从反相位振荡转变为同相位振荡,最后又从同相位振荡过渡到反相位振荡;密度比的变化则对弹性板振荡模式的影响较小。本文的计算结果验证了实验结论,并给出了其他系统参数对2弹性板系统的影响。     

科氏力质量流量计及其在酒类行业的应用

科氏力质量流量计的基本原理是当流体流经一段进行着角振动(同相位振动)的管子时，在管子上就会产生科里奥利力，其大小正比于流体的质量流量。在角振动着的管子上又叠加了一个扭转振动(反相位振动)，扭转角的大小也就正比于流体的质量流量。该流量计于20世纪80年代问世，目前国际上只有美国、德国、英国、日本、丹麦等少数国家能进行生产。能够对浆状、糊状、多相流体、高低温流体、强酸及脉动流体进行测量。可广泛应用于石油、化工、食品、造纸、制药等行业。     

印刷机串墨机构的载荷分布特性研究

印刷机串墨机构的栽荷分布特性是对墙板进行有限元分析的基础。利用动态静力分析法,建立了串墨机构运动副问动裁荷的数学模型;用消元法得到了各运动副反力的解析式。结合实例分析了机构的动裁荷分布特征。研究表明：各运动副反力和反力矩在换向位置均出现突变,引起墙板的振动,从而造成印刷故障。     

Ultradian oscillation of Saccharomyces cerevisiae during aerobic continuous culture: hydrogen sulphide mediates population synchrony

Saccharomyces cerevisiae showed an ultradian respiratory oscillation during aerobic continuous culture. Analysis of the off-gas revealed that hydrogen sulphide production also oscillated. Production was first detected at the onset of low respiration and reached a maximum (1.5 microM) prior to minimum respiratory activity. Then H(2)S concentration fell rapidly to below 0.2 microM before the onset of high respiration. Injection of respiratory oscillation perturbation agents, such as glutathione (50 microM), NaNO(2) (50 microM) or acetaldehyde (4.5 mM),() transiently increased H(2)S production above 6 microM. The synchronization properties of H(2)S were analysed to reveal that changes of oscillation period and amplitude were dependent on H(2)S concentration in culture. It is concluded that H(2)S produced during oscillation produces population synchrony by respiratory chain inhibition.     

对乙酰氨基酚-KBrO_3-H_2SO_4体系化学振荡反应的研究

本文主要研究在CSTR(连续搅拌反应器)条件下一些因素对化学振荡的影响,得到该非催化振荡的最佳条件和振荡范围,以及反应总活化能。BZ型反应催化剂对非催化振荡有不同的影响。本文发现除Mn~(2+),Ce~(3+)之外,{Fe(phen)_3}~(2+)也能使停振的非催化振荡复活。当BZ催化剂加入到非催化振荡体系中。整个体系转变成非催化和催化振荡的藕合体系。实验事实说明:非催化振荡的有机产物是随后催化振荡反应物。在CSTR中利用铂电极和分光光度计同时检测出{Fe(phen)_3}~(2+)的振荡行为。