自走式修井机游动系统仿真模型

为了获得自走式修井机的系统动力学特性 ,在系统动力学仿真软件ADAMS中建立了修井机游动系统的起升和下钻仿真模型 ,成功地用Rack_and_PinionJoint模拟了钢丝绳与滑轮间的缠绕关系 ,用SingleComponentForce模拟出了钢丝绳在起升、下钻过程中刚度的变化过程。对仿真模型在额定工况时的起升、下钻过程进行了仿真运算 ,得到了游动系统中快绳、死绳、各游绳及井架上的最大动载荷和动载系数。仿真结果可用于钢丝绳的选择、井架的设计和使用时参考。该仿真模型中解决钢丝绳与滑轮间的缠绕和钢丝绳的刚度随时间变化的方法也可为研究钻机、矿井提升系统等类似的时变结构系统动力学时借鉴。

对平网印花机游动系统驱动装置的探讨

对平网印花机游动系统驱动装置的探讨赵延雯，徐云程（武汉纺织工学院）平同印花机是我国近几年发展纺织机械新产品的重点设备之一。它广泛用于纯棉、化纤及混纺织物、丝绸、针织物、床单以及各种装饰用布的印花，具有品种适应性广、花回范围大、对花精度高、制造费用低、...

试油提升设备及其游动系统的改进方法探讨

在深井试油作业过程中 ,TJ2 0型通井机与目前油田拥有的井架及游动系统配合使用时 ,由于游动系统的穿绳数以及绞车滚筒与水刹车之间的传动比不合适 ,导致作业效率低。现场使用中 ,存在为提高效率而不挂水刹车的现象 ,致使刹车副磨损严重 ,而且还存在环境污染和安全问题。文章分析了不同绳数游动系统的速度和载荷提升能力 ,为提高TJ2

钻机游动系统运动分析

目前石油高校《钻井机械》＾〔１〕教材中都有钻机游动系统运动分析内容，但不详细，只有绳速和天车滑轮转速的结论，没有运动分析过程，中专《钻井机械》＾〔２〕教材中增加了游车滑轮转速计算公式，同样没有运动分析过程，且公式是错误的。本文从运动学入手，利用速度瞬心法对钻机游动系统的绳速和滑轮转速进行了详细分析，得出正确结论。

复合养殖系统中浮游动物种类丰度及其影响因素

利用人工湿地和养殖塘构建了复合养殖系统,通过设置不同塘间水质差异,调查了斑点叉尾鮰鱼鱼种培育段和成鱼养殖段不同梯度下的浮游动物种类丰度,并探讨了种类丰度与环境因子的关系.结果表明,2养殖阶段的循环塘中,轮虫的种类丰度随养殖密度的增加而升高,浮游甲壳动物随养殖密度的增加而降低.成鱼养殖阶段对照塘中轮虫的种类丰度高于循环塘P1、P2;枝角类和桡足类的丰度则低于P1、P2;高养殖密度塘P3中,3种形态浮游动物种类丰度均低于对照塘.15种环境因子的主成分分析以及种类丰度与环境因子的冗余度分析结果表明,影响浮游动物种类丰度的主要环境因素为水体的营养状态,水体的物理特征对种类丰度的影响较小.

国产全液压钻机的研制与应用

全液压钻机是钻井自动化的一个重要方向。为了提高国产钻机的自动化和智能化水平,研制了具有自主知识产权的全液压钻机。该钻机突破了倍程提升系统、液压控制系统、钻具处理系统等关键技术,可以适应环境条件和地质构造相当恶劣以及钻井费用相当高的地区的钻井工作。同时,具有更好的适应性和经济性。现场试验结果表明,钻机的功能和参数达到设计要求,试验效果良好。国产全液压钻机可以明显减轻工人的劳动强度,使操作更安全,施工质量也得以提高。

ZJ40 DBS数控变频电动钻机的特点及应用

文章介绍了ZJ40DBS数控变频电动钻机性能特点,客观地评价了ZJ40DBS数控变频电动钻机在常规直井和特殊工艺井钻井过程中所起的重要作用和实现的显著成效,应用结果表明,这种电动钻机的性能优良,能延长钻头使用寿命,提高机械钻速,并使钻井更安全、科学。

半潜式钻井平台电子防碰天车设计与改进

在石油钻井领域日常安全生产中,游动系统的安全运转是钻井作业的保障,为了提高钻机的安全可靠性,防止发生游动系统与天车和转盘面发生上碰下砸事故,设计了智能电子防碰天车装置。其中,防碰天车装置游动系统的防上碰下砸保护是一项极其重要的安全措施,一旦发生顶碰天车或者下砸钻台面事故,严重的可造成钻机设备报废,造成重大经济损失和人员伤亡。基于陆地上及自升式井场使用的电子防碰天车,在设计之初未综合考虑半潜式钻井平台升沉补偿器液缸长度对电子防碰天车零位标定的影响,导致传统的电子防碰天车应用于半潜式平台时,无法实现防下砸功能。笔者在借鉴原厂设计资料和实践经历后,对原防碰天车系统进行改进,增加升沉补偿装置液缸长度测量单元,同时对防碰天车功能进行优化,增加伊顿刹车的提前介入和强行切断绞车马达输出功能,从而实现了半潜式平台电子防碰天车的预防下砸功能。

Effects of an artificial reef system on demersal nekton assemblages in Xiangshan Bay, China

In 2012,an artificial reef system was deployed in Xiangshan Bay,China,to enhance its fishery resources. To determine the effect of the artificial reef system on the demersal nekton assemblages,a beforeafter-control-impact study design was applied. Comparisons of assemblages from impact and control habitats revealed that the assemblage in the impact area had a gradual response to reef deployment. The assemblages in the impact and control areas changed in different ways after reef deployment. During the study period,total biomass,species richness and average body weight in the control area remained relatively stable,whereas there were significant increases in these indicators in the impact area. Responses to the reefs differed among nekton species,inducing assemblage succession in the reefs post-deployment. Sparus macrocephalus and Cynoglossus abbreviat us benefited most from reef deployment. Conversely,smallsized shrimp Palaemon gravieri showed a progressive decrease in biomass following reef deployment. Overall,the artificial reef system diversified the demersal nekton assemblage,enhanced the total biomass,and increased the proportion of large-sized species.

Surface Ozone in Jiuzhaigou National Park, Eastern Rim of the Qinghai-Tibet Plateau, China

Located in southwestern China, Jiuzhaigou National Park is one of the most popular tourism destinations in China, famous for its unique aquatic ecosystems and beautiful forests. However, plants in the park may be at high ozone risk as a result of the intensive use of diesel tour buses in the park. In addition, Jiuzhaigou is close to a region with relatively high regional anthropogenic NOn emissions. During the growing season, also the peak season of tourism, we measured ozone concentration at two sites within the Park and these were： Jiuzhaigou Bureau （JB） and Long Lake （LL）. The results indicate that ozone concentrations were not high enough to cause foliar injury during the monitoring period, although the risk of ozone to plants was higher in spring than in summer and autumn. Diurnal ozone cycles at JB and LL displayed significantly higher ozone concentrations in the daytime than in the nighttime, suggesting photochemical production of ozone during the day and ozone deposition during the night as a result of the nocturnal boundary layer. In parallel with the seasonal change of background surface ozone in the Northern Hemisphere, maximum daily 8-h average ozone concentration （MDA8） and daily ozone concentration decreased from spring to autumn at the two sites. This temporal variation in Jiuzhaigou wasmost likely associated with the downward mixing of ozone-rich air from the free troposphere, because all the high-ozone events （MDA8 〉 70.0 ppb） were observed in spring and ozone-rich air from the free troposphere was the dominant cause. In summary, our data suggest that ozone concentrations in Jiuzhaigou were more affected by the regional-scale of background pattern in air quality and meteorological conditions than by local tourist activities.

Dynamic simulation and efficiency analysis of beam pumping system

An improved whole model of beam pumping system was built. In the detail, for surface transmission system(STS), a new mathematical model was established considering the influence of some factors on the STS's torsional vibration, such as the time variation characteristic of equivalent stiffness of belt and equivalent rotational inertia of crank. For the sucker rod string(SRS), an improved mathematical model was built considering the influence of some parameters on the SRS's longitudinal vibration, such as the nonlinear friction of plunger, hydraulic loss of pump and clearance leakage. The dynamic response and system efficiency of whole system were analyzed. The results show that there is a jumping phenomenon in the amplitude frequency curve, and the system efficiency is sensitive to motor power, pump diameter, stroke number, ratio of gas and oil, and submergence depth. The simulation results have important significance for improving the efficiency of beam pumping system.

The Application of Ecosystem Dynamic Model in Xiamen Bay

This paper is to establish a nitrogen and phosphorus nutrients cycle-based numerical model of ecological dynamics for Xiamen Bay on the basis of the existing three-dimensional barocline hydrodynamic model. The calculation results show that the estuarine district of Jiulongjiang estuary has the highest inorganic nitrogen concentration followed by the West Harbor, which demonstrates that Jiulongjiang River is the main input source of inorganic nitrogen in Xiamen Bay. The West Harbor has relatively high concentration of nutrients caused by the huge land pollution emission and its own poor water exchange capacity; while the distribution rules of phytoplankton biomass correspond with those of phosphates, demonstrating Xiamen Bay＇s phytoplankton controlled by phosphorus; the haloplankton biomass differs slightly, presenting the gradual reduction from the interior part to the exterior part of the bay.

Reasoning about Epistemic Actions and Knowledge in Multi-Agent Systems Using Coq

In this paper, the authors outline a formal system for reasoning about agents＇ knowledge in knowledge games-a special type of multi-agent system. Knowledge games are card games where the agents＇ actions involve an exchange of information with other agents in the game. The authors＇ system is modeled using Coq-a formal proof management system. To the best of the authors＂ knowledge, there are no papers in which knowledge games are considered using a Coq proof assistant. The authors use the dynamic logic of common knowledge, where they particularly focus on the epistemic consequences of epistemic actions carried out by agents. The authors observe the changes in the system that result from such actions. Those changes that can occur in such a system that are of interest to the authors take the form of agents＇ knowledge about the state of the system, knowledge about other agents＇ knowledge, higher-order agents＇ knowledge and so on, up to common knowledge. Besides an axiomatic ofepistemic logic, the authors use a known axiomatization of card games that is extended with some new axioms that are required for the authors＇ approach. Due to a deficit in implementations grounded in theory that enable players to compute their knowledge in any state of the game, the authors show how the authors＇ approach can be used for these purposes.

The Mechanism of Rural Tourism Development-Taking Yangshuo County as an Example

Rural tourism plays a crucial role in promoting the process of urban-rural integration and regionally coordinated development.Drawing on theories of tourism system drive and system science,this study constructed a rural tourism system dynamics model with four subsystems:demand,supply,media,and support.Subsequently,we predicted the optimal mechanism for rural tourism development using scenario simulation methods.The findings were four-fold.(1)The rural tourism development dynamics system constructed in this study overcame the limitations of previous subsystem divisions.(2)Under the development scenarios of Natural development mechanism(NDM),Demand driven mechanism(DDM),Supply driven mechanism(SDMe),Media driven mechanism(MDM),Support driven mechanism(SDMu),and Synergistic driven mechanism(SDMy),the rural tourism development index values in 2035 were 0.678,0.702,0.755,0.715,0.776,and 0.836,respectively.Among these scenarios,SDMy emerged as the ideal mechanism for rural tourism development in Yangshuo County.(3)Based on the characteristics of the rural tourism development index,rural tourism in Yangshuo County has undergone three stages:fluctuating growth,rapid development,and recession.(4)Yangshuo County’s rural tourism supply index grows slowly and is always below 0.8,which is a key link for future structural optimization.This study proposes a direction for rural tourism development in Yangshuo and a later impetus,which can accelerate the process of urban-rural integration in Yangshuo and similar areas.

Random walk models for top-N recommendation task

Recently there has been an increasing interest in applying random walk based methods to recommender systems. We employ a Gaussian random field to model the top-N recommendation task as a semi-supervised learning problem, taking into account the degree of each node on the user-item bipartite graph, and induce an effective absorbing random walk (ARW) algorithm for the top-N recommendation task. Our random walk approach directly generates the top-N recommendations for individuals, rather than predicting the ratings of the recommendations. Experimental results on the two real data sets show that our random walk algorithm significantly outperforms the state-of-the-art random walk based personalized ranking algorithm as well as the popular item-based collaborative filtering method.

EFFECT OF KAIROMONE ON PREDATOR-PREY DYNAMICS -- A DELAY MODEL

In most of the predator-prey systems, prey individuals make transitions between vulnerable and invulnerable states or locations. This transition is regulated by various inducible defense mechanisms. Diel vertical migration （DVM） in zooplankton is the most effective and instantaneous defense observed in zooplankton population. Zooplankton shows downward vertical migration in the daytime in the presence of predators （or predator kairomones） to avoid predation （i.e. refuge use）, and it enters into the surface water again at night to graze phytoplankton. The dynamics of the planktonic ecosystem under DVM of zooplankton along with fish kairomone and the multiple delays due to migration for vulnerable and invulnerable prey and reproduction in the predator population is of considerable interest both in theoretical and experimental ecologists. By developing mathematical model, we analyze such a system. The conditions for which the system enters into Hopf-bifurcation are obtained. Moreover, the conditions for which the bifurcating branches are supercritical are also derived. Our results indicate that DVM along with the effect of kairomone and multiple delays with a certain range are responsible to enhance the stability of the system around the positive interior equilibrium point.

EFFECTS OF DELAY AND SEASONALITY ON TOXIN PRODUCING PHYTOPLANKTON-ZOOPLANKTON SYSTEM

A dynamical model for toxin producing phytoplankton and zooplankton has been formu- lated and analyzed. Due to gestation of prey, a discrete time delay is incorporated in the predator dynamics. The stability of the delay model is discussed and Hopf bifurcation to a periodic orbit is established. Stability and direction of bifurcating periodic orbits are investigated using normal form theory and center manifold arguments. Global existence of periodic orbits is also established. To substantiate analytical findings, numerical simu- lations are performed. The system shows rich dynamic behavior including chaos and limit cycles. The influence of seasonality in intrinsic growth parameter of the phytoplankton population is also investigated. Seasonality leads to complexity in the system.

A fractional-order toxin producing phytoplankton and zooplankton system

In this work, we investigate the dynamical behavior of a fractional-order toxin producing on a phytoplankton-zooplankton （TPPZ） system with nutrient cycling. We propose a mathematical system to model this situation. All the feasible equilibria of the system are obtained and the conditions for the existence of the equilibriums are determined. Local stability analysis of the TPPZ is studied by using the fractional Routh-Hurwitz stability conditions. Numerical simulations are carried out for a hypothetical set of parameter values to substantiate our analytical findings.

Rebinding kinetics of dissociated amino acid ligand and carbon monoxide to ferrous microperoxidase-11 in aqueous solution

The rebinding kinetics of an amino acid ligand to ferrous microperoxidase-11 (MP11) after photolysis of aggregated ferrous MP11 was measured in aqueous solution with femtosecond transient visible absorption spectroscopy. The kinetics of CO rebinding to ferrous MP11 after photolysis of MP11CO was also measured in aqueous solution with femtosecond transient visible absorption spectroscopy. From these measurements, we found that either Val-11 or Lys-13 rebinds to ferrous MP11 exponentially with an 8 picosecond time constant in aggregated ferrous MP11 solution and that CO rebinds to ferrous MP11 nonexponentially with subnanosecond time scale in MP11CO solution. The kinetics of both the amino acid and CO rebinding to ferrous MP11 in MP11 system mimics that in carbon monoxide oxidation activator protein (CooA) or carboxymethyl cytochrome c (CmCytC) system. We also measured the kinetics of CO rebinding to ferrous MP11 in aqueous solution at different MP11CO concentrations and found that MP11CO concentration has an obvious effect on the kinetics of CO rebinding to ferrous MP11, where both the germinate yield and rate of CO rebinding to ferrous MP11 increase with the increase of MP11CO concentration. These findings suggested that the picosecond amino acid ligand rebinding process could disturb the proximal heme-ligand structure that possibly leads to the subnanosecond CO rebinding kinetics in MP11CO, CooACO and CmCytCCO systems.