Stiffness Characteristics of a Basic Nonlinear Air Spring Model

This study predicts the characteristics of a compressible polytropic air spring model. A second-order nonlinear autonomous air spring model is presented. The proposed model is based on the assumption that polytropic processes occur. Isothermal and isentropic compression and expansion of the air within the spring chambers are the two scenarios that are taken into consideration. In these situations, the air inside the spring chambers compresses and expands, resulting in nonlinear spring restoring forces. The MATLAB/Simulink software environment is used to build a numerical simulation model for the dynamic behavior of the air spring. To quantify the values of the stiffnesses of the proposed models, a numerical solution is run over time for various values of the design parameters. The isentropic process case has a higher dynamic air spring stiffness than the isothermal process case, according to the results. The size of the air spring chamber and the area of the air spring piston influence the air spring stiffness in both situations. It is demonstrated that the stiffness of the air spring increases linearly with increasing piston area and decreases nonlinearly with increasing air chamber length. As long as the ratio of the vibration’s amplitude to the air spring’s chamber length is small, there is good agreement in both scenarios between the linearized model and the full nonlinear model. This implies that linear modeling is a reasonable approximation of the complete nonlinear model in this particular scenario.

An Air Mass Based Approach to the Establishment of Spring Season Synoptic Characteristics in the Northeast United States

The Northeast United States spring is indicative of major meteorological and biological change though the seasonal boundaries are difficult to define and may even be changing with global climate warming. This research aims to obtain a synoptic meteorological definition of the spring season through an assessment of air mass frequency over the past 60 years. The validity of recent speculations that the onset and termination of spring have changed in recent decades with global change is also examined. The Spatial Synoptic Classification is utilized to define daily air masses over the region. Annual and seasonal baseline frequencies are identified and their differences are acquired to characterize the season. Seasonal frequency departures of the early and late segments of the period of record are calculated and examined for practical and statistical significance. The daily boundaries of early and late spring are also isolated and assessed across the period of record to identify important changes in the season’s initiation and termination through time. Results indicate that the Northeast spring season is dominated by dry air masses, mainly the Dry Moderate and Dry Polar types. Prior to 1975, more polar air masses are detected while after 1975 more moderate and tropical types are identified. Late spring is characterized by increased variability in all moist air mass frequencies. These findings indicate that, from a synoptic perspective, the season is dry through time but modern springs are also warmer than those of past decades and the initiation of the season is likely arriving earlier. The end of the season represents more variable day-to-day air mass conditions in modern times than detected in past decades.

Simulation Research on an Active Anti-Roll System for an Air Spring Passenger Car

To reduce the roll movement of an air spring passenger car, an active anti-roll system is developed, which is constructed with hydraulic and pneumatic units to change spring rate during cornering. For the comparing research between the passive and active system, a two-track vehicle model and a co-simulation model of air spring system are built. For the simulation research on the linear movement of the actuator, a mathematical model is considered as dynamical subsystem in the co-simulation model. To active control the roll angle of vehicle body, a sliding-mode controller with optimized control parameters for the test vehicle is introduced into the model. The characteristics of sliding-mode controller is discussed and the validation of active antiroll control is proved by comparison with other control methods. The results show that the roll angle of air spring vehicle is reduced obviously with the active anti-roll actuator in comparison with that of the passive system. Compared with other control methods, sliding-mode controller has an advantage of shortest switching times, which leads to a longer lifetime of actuator and valves.

The error research on vertical rigidity theory’s formula of airborne air spring

On the basis of analyzing the result of numerical simulation and that of theoretical analysis,the systematic error of some air spring's theoretical formula is researched. The result shows that the vertical stiffness's theoretical formula of air spring owes the systematic error. And the systematic error is relative to the three supposed conditions which are used in the process of theoretical deduction. However,the systematic error is small enough so that the supposed conditions of theoretical formula are reasonable. Moreover,with the increase of initial inner pressure,the systematical error increases.

A Hybrid Structure of Dual Stators and a Pneumatic Spring for Resonance Control in an Air Mount

An active device using electromagnetic forces was constructed and examined for the purpose of minimizing the resonance in air mounts of clean rooms. The air mounts are vulnerable to low-frequency resonance due to heavy weight and low stiffness. A hybrid structure of the active device, composed of pneumatic and electromagnetic parts, was developed and tested. The pneumatic parts in the device support heavy weights under the air mounts, and the electromagnetic parts reduce the resonance. The electromagnetic parts are composed of dual stators and an armature, which surround the pneumatic parts. The resonance can decrease when electromagnetic forces are generated in the gaps between the stators and the armature. Four active devices were installed under a 3-ton surface plate for a vibration test apparatus. The vibration was detected by eddy-current sensors. Discrete P Control logic was based on displacement, and embedded in a C6713 DSP. The results from impact tests show that the peak magnitude in the resonance frequency can be reduced to –10 dB.

Analytical approach for the design of convoluted air suspension and experimental validation

An improved analytical design to investigate the static stiffness of a convoluted air spring is developed and presented in this article.An air spring provides improved ride comfort by achieving variable volume at various strokes of the suspension.An analytical relation is derived to calculate the volume and the rate of change in the volume of the convoluted bellow with respect to various suspension heights.This expression is used in the equation to calculate the variable stiffness of the bellow.The obtained analytical characteristics are validated with a detailed experiment to test the static vertical stiffness of the air spring.The convoluted air bellow is tested in an Avery spring-testing apparatus for various loads.The bellow is modeled in the ABAQUS environment to perform finite element analysis(FEA)to understand and visualize the deflection of the bellow at various elevated internal pressures and external loads.The proposed air spring model is a fiber-reinforced rubber bellow enclosed between two metal plates.The Mooney-Rivlin material model was used to model the hyperelastic rubber material for FEA.From the results,it is observed that the experimental and analytical results match with a minor error of 7.54%.The derived relations and validations would provide design guidance at the developmental stage of air bellows.These expressions would also play a major role in designing an effective active air suspension system by accurately calculating the required stiffness at various loads.

Analyses of spring mean circulations for major andminor dust storm years in China-Mongolia area

To better understand the dust storm (hereafter DS) inducing circulation in the China-Mongolia (CM) DS activity area,the spring mean circulation features and differences on lower levels in three subregions of the CM DS area for the majorandminor-DS years have,as a whole (not partly),been analyzed,utilizing the National Centers for Environmental Prediction and the National Center for Atmospheric Research (NCEP/NCAR) reanalyzed gridded data,the observed DS frequency data in the CM area,and the composite analysis method.The main conclusions are as follows:(1) Judging from the differences in the DS-inducing systems,dust origins,paths of invading cold air,and main DS-strike areas,the whole CM DS area is roughly divided into the three subre-gions:the East-,Middleand West-CM subregions (in this paper,referred to as E-,M-,and W-CM).(2) In major DSs during spring over the E-CM,the middleand lower-level troughs or cyclones over the Japan Sea and northeastern China (NEC) domi-nate.The invading cold air along the northeastern (NE) or north by east (NE) path often causes the DS in the E-CM region.But nearly the opposite is true inminor DS during spring in E-CM.(3) In the major DS during spring over the M-CM region,the Mongolian troughs or cyclones are the main DS-inducing systems.The strong invading cold air along the northwestern (NW)or north by west (Nw) path causes the DSs in the M-CM region.(4) In the major DSs during spring over the W-CM region,the South Xinjiang heat lows prevail,the intruding cold air has a western path,and creates the DSs in South Xinjiang.(5) In the past 50 years,the DSs over the M-CM region have had the most severe impact on the preceding three subregions of the CM DS area.Overall,DS activities over all of three regions of the CM area decreased in the past (particularly,over Mand W-CM regions since the mid-1980s.But there existed a short and sudden increasing in E-CM in the years 2000-2002.(6) It is circulation changes and desertification evolutions that cause the yearly and decadal changes of DS in CM area,especially the former.With the backdrop of global warming in the future,perhaps the decreased DS activities over Mand W-CM will persist for some time again,and special attention should be paid to ones over E-CM or to the individual DS events over Mand W-CM.

Particulate matter trends and quantification of the spring sand-dust contribution in Hohhot,Inner Mongolia,from 2013 to 2017

On 10 September 2013,the State Council promulgated the Action Plan for the Prevention and Control of Air Pollution(hereinafter referred to as the Action Plan).To study the variations in the air pollutant concentrations in Hohhot during the implementation of the Action Plan and the effects of various measures,the daily concentrations of air pollutants(fine particulate matter(PM_(2.5)),inhalable PM(PM 10),SO_(2),and NO_(2))in Hohhot published by the China Environmental Monitoring Station were obtained to analyze the general meteorological conditions in Inner Mongolia from 2013 to 2017.The variations and causes of the ambient PM concentration in Hohhot were examined,and the quantitative influence of sandstorms on the ambient PM concentration in Hohhot was analyzed by selecting the spring season with frequent sandstorms as an example.The results showed the following.(1)The air quality in Hohhot continuously improved,and compared with those in 2013,the PM_(2.5)and PM 10 concentrations decreased by 24.6%and 48.2%,respectively,in 2017.However,the air pollutant concentrations remained high,with the average PM_(2.5)and PM 10 concentrations exceeding the national secondary standards by 22.9%and 35.7%,respectively.(2)The reductions in the spring PM_(2.5)and PM 10 concentrations were 5.6%and 8.9%,respectively,and the annual decreases in the PM_(2.5)and PM 10 concentrations were 3.6 and 15.1μg m^(−3)yr−1,respectively,from 2013 to 2017.(3)The absolute contribution ranges of dust weather to the concentrations of PM_(2.5),PM 10,and TSP during 2013–17 were 0.6–5.2μg m^(−3),9.0–16.9μg m^(−3),and 14.7–30.0μg m^(−3),respectively,in Hohhot during the spring.

Precursor Role of Winter Sea-Ice in the Labrador Sea for Following-Spring Precipitation over Southeastern North America and Western Europe

The role of winter sea-ice in the Labrador Sea as a precursor for precipitation anomalies over southeastern North America and Western Europe in the following spring is investigated. In general terms, as the sea ice increases, the precipitation also increases. In more detail, however, analyses indicate that both the winter sea-ice and the sea surface temperature(SST)anomalies related to increases in winter sea-ice in the Labrador Sea can persist into the following spring. These features play a forcing role in the spring atmosphere, which may be the physical mechanism behind the observational relationship between the winter sea-ice and spring precipitation anomalies. The oceanic forcings in spring include Arctic sea-ice anomalies and SST anomalies in the tropical Pacific and high-latitude North Atlantic. Multi-model Coupled Model Intercomparison Project Phase 5 and Atmospheric Model Intercomparison Project simulation results show that the atmospheric circulation response to the combination of sea-ice and SST is similar to that observed, which suggests that the oceanic forcings are indeed the physical reason for the enhanced spring precipitation. Sensitivity experiments conducted using an atmospheric general circulation model indicate that the increases in precipitation over southeastern North America are mainly attributable to the effect of the SST anomalies, while the increases over Western Europe are mainly due to the sea-ice anomalies. Although model simulations reveal that the SST anomalies play the primary role in the precipitation anomalies over southeastern North America, the observational statistical analyses indicate that the area of sea-ice in the Labrador Sea seems to be the precursor that best predicts the spring precipitation anomaly.

Seasonal air temperature variations retrieved from a Geladaindong ice core, Tibetan Plateau

A 70-year history of precipitation δ^18O record has been retrieved using an ice core drilled from a plat portion of the firn area in the Guoqu Glacier （33°34＇37.8″ N, 91°10＇35.3″ E, 5720 m a.s.l.） on Mt. Geladaindong （the source region of Yangtze River） during October and November, 2005. Based on the seasonality of δ^18O records and the significant positive relationships between monsoon/non-monsoon δ^18O values and summer/spring air temperature from the nearby meteorological stations, the history of summer and spring air temperature have been reconstructed for the last 70 years. The results show that both summer and spring air temperature variations present similar trends during the last 70 years. Regression analysis indicates that the slope of the temperature-δ^18O relationship is 1.3℃/‰ for non-monsoon δ^18O values and spring air temperature, and 0.4℃/‰ for monsoon δ^18O values and summer air temperature. Variation of air temperature recorded in the ice core is consistent with that in the Northern Hemisphere （NH）, however, the warming trend in the Geladaindong region is more intense than that in the NH, reflecting a higher sensitivity to global warming in the high elevation regions. In addition, warming trend is greater in spring than in summer.

基于Spring Boot的空调能耗智能控制系统的设计与实现

空调能耗智能控制系统是一种对公共区域空调使用采取智能控制管理的软件系统,包含硬件系统和软件系统两部分。将解决生活中人不在时未关闭空调,不能有效地控制空调温度等能耗的浪费,公共区域空调不方便控制。该系统基于Java Web、Java Bean、Spring Boot、My Batis技术,实现了控制设备、监测设备、管理设备、管理策略等功能,有效地解决了一些人离开空调忘记关闭,室内温度过低或过高等造成能耗浪费,公共区域空调集体控制等难题。

仿猫类落地姿态的准零刚度隔振器

对设备加装隔振装置是保证其高效工作的重要方法之一.本文从仿生学的角度,根据猫科动物落地时优秀的抗冲击能力,通过观察其落地动作姿态,利用非线性补偿原理,以空气弹簧作为正刚度结构,设计出一种具有非对称刚度特性的高静低动刚度隔振器.以其为研究对象,建立了动力学模型,利用特定的方法对非对称刚度系统进行分析求解,并与数值结果和有限元仿真结果进行对比.结果表明,在较低阻尼以及较高激励幅值下,还会出现倍周期响应甚至混沌响应.同时,通过将本文设计的隔振结构和单一空气弹簧的隔振性能对比,可以得到隔振效果明显优于单一空气弹簧的结论,从而验证了所设计隔振结构的有效性和可行性.

春茶萌芽期复杂地形下冷池气温特征及易发区识别

以西湖龙井主要产区为研究区域,利用2021年研究区内29个自动气象站春茶萌芽期的气温和雷达探空逆温数据,分析典型冷池易发区的冷池气温特征,探索基于DEM自动识别复杂地形下的冷池易发区方法。结果表明:2021年2月20日-3月31日,西湖龙井产区典型冷池易发区的冷池日发生频率为45%。冷池日发生频率和强度与天气类型有关,晴天和多云天气条件下极易出现冷池日,寡照天气下较少发生,强冷池日多出现于晴天条件。冷池增加了逆温频率和强度,与平地相比,逆温频率增加了23%,平均最大逆温强度增加了1.26℃·100m^(-1)。一次典型的强冷池过程包含了形成加强、维持和消弱消散3个阶段,消弱消散阶段谷底的最大小时升温幅度达到11.3℃,比形成加强阶段最大小时降温幅度(7.2℃)高4.1℃。由DEM数据中的坡度、相对高度百分率、地形曲率3个地形因子构建判别指标识别冷池易发区,识别效果较好,对冷池易发区和非易发区站点的识别准确率分别为80%和78%。研究区内茶园有约26%面积分布在冷池易发区内,因极端低温和剧烈升温过程影响,更易在春茶萌芽期导致春茶受霜冻危害。

空气弹簧自由边界模拟控制策略研究

针对空气弹簧水平多点支撑自由边界模拟系统存在的过约束、难收敛和非线性控制问题,首先,采用自由度解耦控制方式,在削弱系统内力的基础上,将空间自由度的控制目标分解为每一个控制通道的控制目标,解决了系统过约束问题;其次,利用改进积分分离(proportion integration differentiation,简称PID)控制算法克服系统超调,解决了系统震荡收敛问题;最后,采用经验数据对空气弹簧刚度进行实时二维插值补偿,解决了系统非线性问题。实测结果表明,该控制系统设计合理,系统运行过程平稳,通道间同步性较好,控制策略满足模态试验边界的模拟要求。

轨道车辆空气弹簧刚度试验统型设计与研究

为实现轨道车辆空气弹簧静态和动态刚度试验模块化、标准化统型设计目标,对试验统型设计思路进行了分析;设计了一种新型的空气弹簧径向轴向组合密封模块化试验装置,并与传统密封装置进行了对比;重点利用新型装置探究了不同加载速度对刚度的影响,以及受迫和自由这两种不同振动方式对动刚度、阻尼、共振频率、共振倍率的影响。结果表明:统型试验装置能够满足试验要求,且装置数量减少了50%,存放空间缩减了50%,设计效率提高了60%,加载速度对静刚度的影响并不明显,受迫和自由这两种不同振动方式所测试的动态性能数据基本一致。

空气弹簧-铅芯橡胶支座三维隔震装置力学性能

为提高柔性建筑结构的隔震能力,提出一种兼具水平和竖向隔震功能的空气弹簧-铅芯橡胶支座(AS-LRB)三维隔震装置.介绍了该三维隔震装置的构造,分别对该三维隔震装置水平和竖向力学性能进行了试验研究,提出了该三维隔震装置水平和竖向力学性能参数的计算方法.研究结果表明:该三维隔震装置采用空气弹簧(AS)进行竖向隔震,采用铅芯橡胶支座(LRB)进行水平隔震;竖向隔震的载荷-位移曲线表现出非线性变化的特点,其竖向力学性能受空气弹簧气压的影响明显;水平隔震的耗能能力强,其水平力学性能受加载幅值和空气弹簧气压的影响明显.通过与试验结果的对比表明,所提出的计算方法能够准确地计算该三维隔震装置的水平和竖向力学性能参数.

大跨度钢桁架隔震结构隔震性能及影响规律分析

由于大跨空间结构竖向振动问题突出,水平隔震支座难以有效控制结构的竖向地震响应。将摩擦摆水平隔震支座和空气弹簧-摩擦摆三维隔震支座应用于大跨度钢桁架中,分析钢桁架水平隔震结构和三维隔震结构的隔震控制效果。结果表明,水平隔震和三维隔震均延长了结构自振周期,隔震后一阶振型为上部桁架结构沿水平方向的整体平动。时程分析显示,在普通地震动、近断层脉冲型地震动和远场长周期地震动作用下,水平隔震支座对桁架水平和竖向节点峰值加速度的平均隔震率分别为43.4%和9.2%,三维隔震支座对桁架水平和竖向节点峰值加速度的平均隔震率分别为43.8%和24.4%,水平隔震支座和三维隔震支座对桁架峰值等效应力的平均隔震率分别为4.2%和17.7%。水平隔震支座和三维隔震支座对桁架水平地震响应控制效果基本相同,三维隔震支座对结构的竖向地震响应控制效果更好。

基于灵敏度分析的某商用车悬架系统参数优化

为提高某商用车的行驶平顺性,对某商用车悬架系统参数进行了优化.基于空气弹簧试验数据拟合得到其刚度特性曲线,建立前后悬架及整车多体动力学模型,仿真得出该车随机输入工况和脉冲输入工况平顺性.搭建悬架系统参数化的多平台联合仿真模型,通过全域灵敏度分析得出悬架系统设计参数对平顺性的影响程度.建立整车平顺性多目标响应面近似模型,利用多目标遗传优化算法进行参数可行域内寻优.结果表明:在随机输入工况下,车速为100 km/h时,驾驶员处和乘客处加权加速度均方根值分别减小了12.50%和29.71%;在脉冲输入工况下,车速为30 km/h驾驶员处和车速为20 km/h乘客处的垂向最大加速度分别减小了14.69%和31.28%,优化效果明显.

振动台控制室抗倾斜空气弹簧三维隔振平台研究

大型地震模拟振动台的运行给周围环境带来不可忽略的振动问题,影响精密仪器设备的正常使用及工作人员的舒适度。针对国家大型地震工程模拟研究设施振动台控制室面临的振动问题,提出一种基于带附加气室的空气弹簧和抗倾斜装置的大质量三维隔振平台。开展了隔振部件以及隔振平台的试验研究以及数值模拟分析,提出了抗倾斜装置的抗倾斜刚度理论计算公式。研究结果表明,带附加气室的锥型与直筒型膜式空气弹簧可实现约1 s竖向隔振周期,阻尼比达23%。试验中抗倾斜装置可有效控制人员偏心荷载造成的平台倾斜问题,平台倾斜角度减小达66%。所设计国家大型地震工程模拟研究设施隔振平台可大幅降低振动台运行产生振动影响,隔振效率达86%以上。

高速动车组空气弹簧内部流场分析及其对动力学特性的影响

空气弹簧作为高速动车组二系悬挂中的重要元件,直接影响了车辆的运行品质,如何建立更加贴近实际的空气弹簧模型逐渐成为车辆动力学分析的重点。基于流体力学理论对空气弹簧内部气体方程进行了推导,依据动网格理论建立了空气弹簧流体力学模型,并通过台架试验验证了模型的准确性。探索了空气弹簧系统内部湍流的计算方法,研究了空气弹簧不同载荷下的刚度特性,进一步分析了空气弹簧的动态特性。研究空气弹簧系统结构参数对垂向特性的影响,通过对管路不同结构参数下Helmholtz共振频率的计算,得出当空气弹簧激振频率与Helmholtz共振频率相同时,会增大空气弹簧阻尼系数。不同连接管路直径下,频率在1.0~5.0 Hz内,随着频率的增大,动刚度明显增大,当频率大于5.0 Hz之后,动刚度逐渐减小并趋于水平;频率在0.5~5.0 Hz内,连接管路直径越小,阻尼系数越大且具有一定滞后性,当频率大于10.0 Hz之后,阻尼系数趋近于0。不同连接管路长度下,频率在1.0~7.0 Hz内,频率越大动刚度越大,当频率大于7.0 Hz之后,随着频率的增加,动刚度逐渐减小并趋于稳定;频率在1.0~9.0 Hz内,连接管路长度越短,空气弹簧阻尼系数越小。