A human-sensitive frequency band vibration isolator for heavy-duty truck seats

In this study,a human-sensitive frequency band vibration isolator(HFBVI)with quasi-zero stiffness(QZS)characteristics for heavy-duty truck seats is designed to improve the comfort of heavy-duty truck drivers on uneven roads.First,the analytical expressions for the force and displacement of the HFBVI are derived with the Lagrange equation and d'Alembert's principle,and are validated through the prototype restoring force testing.Second,the harmonic balance method(HBM)is used to obtain the dynamic responses under harmonic excitation,and further the influence of pre-stretching on the dynamic characteristics and transmissibility is discussed.Finally,the experimental prototype of the HFBVI is fabricated,and vibration experiments are conducted under harmonic excitation to verify the vibration isolation performance(VIP)of the proposed vibration isolator.The experimental results indicate that the HFBVI can effectively suppress the frequency band(4-8 Hz)to which the human body is sensitive to vertical vibration.In addition,under real random road spectrum excitation,the HFBVI can achieve low-frequency vibration isolation close to 2 Hz,providing new prospects for ensuring the health of heavy-duty truck drivers.

Design and Implementation of Library Seating Management System

The library seating management system is an important part of the library’s modern services. The system is based on the Spring and Spring Boot framework, and the system realizes a series of functions such as real-time query, reservation, and cancellation of seat resources, providing users with great convenience. With a simple operation, users can know the availability of seats in the library in real time and reserve them according to their needs. At the same time, the system also provides rich management functions, enabling administrators to easily configure and manage seat resources. The addition, deletion, modification and review of users, the generation of seats, the viewing of user usage records, and the addition or deletion of points for users’ usage can also be carried out. This not only improves the management efficiency, but also provides more scientific and accurate data support for the management of the library. The system not only optimizes the user experience, but also promotes the scientific management and efficient utilization of library resources, and provides strong support for the modern services of the library.

TRAMO/SEATS在危机事件中对旅游影响研究的应用

国内外对旅游危机事件的研究集中于管理方面,近年相关热点转向对旅游影响的研究。以往定性研究多,从经济数量模型进行定量分析研究的较少。本文使用在经济金融领域使用广泛的ARIMA改进版——TRAMO/SEATS方法评估危机事件,如疾病、地震等突发事件对中国旅游业的影响。作为欧盟各国统计局主要统计方法,TRAMO/SEATS方法能够最大程度地反映旅游业季节性波动的特点。通过该方法对2003年在中国内地和香港地区爆发的SARS进行实证研究,分析评估该危机事件的长期影响。在此基础上提出,国家短期内应当通过提高产品质量和拓展高质量的细分市场实现旅游效益型增长;恢复后期才可以推出更为直接的促销手法实现旅游数量型增长,采取刺激旅游人数快速增长的政策和措施。

监管政策对商业银行行为选择的冲击效应研究——基于H省若干家商业银行的TRAMO/SEATS检验

根据《巴塞尔协议》等国际公约的要求,中国的银行监管部门于2004年1月开始,在全国的银行系统推行严格的资本充足性管理。作为国际银行界主流的监管政策,资本充足性管理对商业银行的行为选择产生了深远的影响。本文选取了中国中部某省份2002年至2006年的商业银行数据,针对包括贷款对象结构、贷款期限结构和风险偏好结构三个表征商业银行行为特征的24个数据序列,运用TRAMO/SEATS的技术方法,实证检验了所有序列的结构性变动点以及监管政策的冲击效果。研究显示,当监管当局开始实施严格的资本充足性监管时,大多数商业银行都降低了风险偏好,说明监管政策的冲击效应十分明显;但是经过大约一年后,几乎所有的商业银行又选择恢复到初始状态,开始增加风险偏好,说明存在商业银行的资本约束软化效应。因此,若要保持资本监管政策的长期效果,还需不断完善相关制度体系建设。本文从商业银行行为变化的特征出发,提出了我国应对《巴塞尔协议Ⅲ》挑战的若干建议。

基于频域的X-13ARIMA-SEATS季节调整过滤器诊断

本文从频域角度对X-13ARIMA-SEATS季节调整程序的对称和并行过滤器进行研究,考察不同的模型非季节和季节移动平均参数以及不同过滤器长度对平方增益函数和相位延迟函数的影响,并以中国采购经理人指数(PMI)和居民消费价格指数(CPI)季节序列诊断为例,从频域角度比较X-11和以ARIMA为基础的AMB方法的平方增益函数和相位延迟函数来选择更优的季节调整方法。研究结论为:(1)非季节移动平均参数增大时,两种过滤器平方增益函数有下降趋势,季节移动平均参数增大时,平方增益函数有上升趋势。长度较短的过滤器波动更剧烈,季节频率上波谷宽度更宽。(2)季节移动平均参数越大时,相位延迟函数震荡越剧烈,非季节移动平均参数越大时,季节频率上的相位延迟增大。单个非季节频率区间内相位延迟函数与平方增益函数有反向关系。(3)AMB方法在非季节频率区间上的增益函数比X-11方法更趋于1,过滤器的凹槽比X-11方法更窄,且频率分量的相位失真更小,在PMI季节调整中更好;X-11方法对称过滤器的平方增益函数更小且更趋于1,在非频率区间上的相位延迟函数比AMB方法更小,更适用CPI的季节调整。(4)与传统季节调整质量诊断相比,频域诊断在估计季节成分的稳定性和过滤器的延迟特性方面具有优势,在季节调整方法选择时可综合两方面的结论。

Experimental study on the working performance of different milling tools for multistage fracturing ball seats

To achieve the secondary production in multistage fracturing wells of tight oil,milling tools are usually used to remove the multistage fracturing ball seats to achieve production with a large diameter in later.In this paper,first of all,the working mechanism of milling tools for multistage fracturing ball seats was studied and a mechanical analysis model of single abrasive grain was established.Then,an experimental system for milling tools was developed,and the experimental tests of the flat,the blade,and the slope milling tool were conducted in order.Besides,the morphology of chips and the surface morphology of the workpiece after the experiment were analyzed.Also,the working performance of milling tools was evaluated from the perspectives of working safety,working efficiency,and wear resistance of the milling tool.The results show that the torque of the milling tool increases nonlinearly with the increase in the cutting depth of the abrasive grain and increases linearly with the increase in the cutting width.Also,the chips are irregular particles and the size is mainly from 10 to 50μm.So,the chips should be pumped up with a small pump pressure and a large displacement.Besides this,the cutting depths of the abrasive grains are from 216.20 to 635.47μm and the bottom surface of the milling tool should be eccentric to avoid the zero point of cutting speed.Furthermore,the torque of the slope milling tool is 23.8%larger than that of the flat milling tool,which is also 30.4%smaller than that of the blade milling tool.Compared with the flat milling tool,the working efficiency of the blade milling tool improves by 79.9%and the slope milling tool improves by 111.1%.Also,the wear resistance of the blade milling tool decreases by 102.7%,while the slope milling tool declines by 32.6%when compared with the flat milling tool.Therefore,the slope milling tool has the characteristics of moderate torque,stable working conditions,the highest working efficiency,and fine wear resistance,which is preferably used to mill multistage fracturing ball seats.This study provides a theoretical basis and guidance for milling multistage fracturing ball seats on-site and realizing production with a large diameter in later stages of multistage fracturing wells.

基于TRAMO-SEATS的月售电量预测方法及应用

为提高月售电量预测准确度,引入TRAMOS-SEATS季节调整方法和Hodrick-Prescott滤波法将月售电量分解为趋势分量、季节分量、循环分量和不规则分量,消除了各分量之间的相互影响。采用ARIMA方法对趋势分量进行预测,采用Holt-Winters加法模型对季节分量进行预测,采用历史同期同类平均值法对循环分量和不规则分量进行预测,最后得到月售电量预测结果。应用实际算例对月售电量进行预测并与实际数据进行对比,验证法方法的正确性与有效性。

基于TRAMO/SEATS的北京月度入境游预测模型研究

本文运用在经济金融领域使用广泛的方法—TRAMO/SEATS方法对北京入境旅游人数开展短期预测研究。作为欧盟各国统计局主要统计方法,TRAMO/SEATS模型由于能有效提取时间序列数据中的信息,不仅预测精度高,而且稳定,能够最大程度地反映旅游业季节性波动的特点。实证分析表明,TRAMO/SEATS模型在北京入境旅游人次的短期预测方面预测能力极佳,能够为北京市入境旅游的短期经营策略提供良好的预测数据。

Ghana＇s Presidential Seats and Sword of State： Aesthetic Manifestation of Kwame Nkrumah＇ s Cultural Policy on Ghana＇s Political Culture

This study explores the aesthetic dimensions of Kwame Nkrumah＇s cultural policies in the creation of Ghana＇s Presidential Seats and the State Sword. The study is an Art Historical research situated within the qualitative research paradigm. It had a population of a defmed class of cultural policy makers, art historians, traditional rulers, nationalists, visual artists and Ghanaians resident both in and outside Ghana. The study examined how the creation of Ghana＇s Presidential Seats and the State Sword were influenced by Kwame Nkrumah＇s cultural policies and the cultural significance of the aesthetic interplay of ethnic insignias used in capturing the Ghanaian concept of Political authority. The study revealed that, Nkrumah recognised the cultural art forms and elements of ethnic Ghana as assets for national development. In line with his policy of building the Nation State of Ghana, he used ethnic cultural art forms and elements. At independence, Nkrumah commissioned some visual artist to create some artistic pieces （politico-cultural artefacts） for the Ghanaian political authority with inspiration or based on what pertains in the traditional authority （Chieftaincy） of Ghana. Politico-cultural artefacts as used in this study refer to the artefacts produced based on the cultural concepts of the ethnic states for the use of the political authority of the Republic of Ghana. Among these artistic pieces are the three Presidential Seats, The State Sword, The President＇s Personal Standard Pole and the State Mace.

Numerical study on erosion behavior of sliding sleeve ball seat for hydraulic fracturing based on experimental data

The sleeve sealing ball seat is one of the important components in the multistage fracturing process of horizontal wells.The erosion and wear of the surface will decrease the sealing performance of the fracturing ball and the ball seat.This leads to pressure leakage during the fracturing process and fracturing failure.In this paper,combined with the actual ball seat materials and working conditions during the fracturing process,the erosion tests of ductile iron and tungsten carbide materials under different erosion speeds,angles,and mortar concentrations are carried out.Then the erosion test results were analyzed by mathematical fitting,and a set of erosion models suitable for sliding sleeve setting ball seat materials were innovatively established.For the first time,this paper combines the erosion model obtained from the experiment and the computational fluid dynamics(CFD)with Fluent software to simulate the erosion of the ball seat.Based on the simulation results,the morphology of the sliding sleeve seat ball after erosion is predicted.Through analysis of the test and simulation results,it is showed that the erosion rate of tungsten carbide material is lower and the wear resistance is better under the condition of small angle erosion.This research can offer a strong basis for fracturing site selection,surface treatment methods,and prediction of failure time of ball seats.

Adaptive Seat Cover for Motorsports and Daily Driving Situations

Automotive seat design presents an ongoing challenge as it involves balancing conflicting customer requirements, ranging from comfort and support to adaptability for diverse body types and custom-molded fit. Original equipment manufacturers often struggle to address the diverse needs dictated by the environment of use in automotive seat design. In response to these deficiencies, this paper employs the design thinking approach/model to explore the gaps in automotive seats comprehensively. The study provides valuable recommendations and documents the exploratory work carried out to bridge these gaps and enhance the overall automotive seat design. By utilizing design thinking principles, this research aims to pave the way for innovative solutions that meet the evolving demands of drivers, ensuring a more comfortable and safer driving experience for daily driving, and better performance for motorsports. Additionally, we present a comprehensive three-phase rapid prototyping approach to develop and showcase the functions of race car modifications, aiming to demonstrate their efficacy and gather valuable feedback from potential customers. By recognizing the significance of nurturing beginners’ interest and skill development, the motorsports community can encourage wider participation and ensure a vibrant future for the sport. .

Registration of the Seated Condylar Position (SCP/CR): Part I: Rationale

The purpose of this paper is to present the rationale for registration of the Seated Condylar Position (SCP)/Centric Relation (CR) position of the condyles.

Registration of the Seated Condylar Position (SCP/CR): Part II: Technique: The Two-Piece Wax Bite Registration

The purpose of this paper is to present the technique for registration of the Seated Condylar Position (SCP)/Centric Relation (CR) position of the condyles: a two-piece wax bite registration with deprogramming and no mandibular manipulation.

基于中国乘员的汽车座椅乘坐姿态舒适性评价分级模型

为研究汽车座椅乘员姿态舒适性问题,针对影响乘员舒适性的矢状面姿态角度指标,文中提出了一种基于中国人群覆盖范围和博弈组合赋权的评价分级方法。首先,采用动作捕捉技术获取乘员各舒适姿态角度,得到角度覆盖的人群范围,从而计算各姿态角度指标得分;采用G1法和熵权法分别计算各指标的主客观权重,基于博弈组合赋权得到各指标的综合最优权重;最终,根据各指标得分及最优权重,按照加权平均方式得到汽车座椅整体姿态舒适性评分;制订5级分级标准获取汽车座椅乘坐姿态舒适性等级。通过被试乘坐汽车座椅的主观体验评分验证建立的分级模型的可行性,为国内智能座舱的座椅姿态调节模式优化设计提供指导和依据。

共享汽车驾驶员适宜H点和座椅参数实验研究

共享汽车具有车型统一、用户多变且使用频率高的特点,为提升共享汽车使用效率和驾乘体验,研发一种能根据驾驶员特征自动调节舒适坐姿的智能座椅意义重大。本文针对用户座椅调节存在的主观任意性导致的座椅舒适性问题,结合共享汽车智能座椅项目,以座椅H点前后位置、H点高低位置、坐垫角和靠背角4个变量为研究因子进行台架实验,分别研究5th、50th和95th百分位驾驶员的座椅舒适性受座椅参数的影响规律。首先,每个研究因子在参考车型范围内均匀选取3个实验水平,采用正交实验表对实验次数进行简化,确定正交实验须进行的组数并进行正交台架实验。实验人员对每组的座椅舒适性进行主观评价,同时通过压力测量仪和数显角度尺测量实验人员的体压分布信息和关节角度信息;其次,通过聚类分析确定了本文采用的以关节角度为客观参数的主客观舒适性评价体系,通过正交实验分析,得出了不同座椅参数对座椅舒适性的影响存在差异的结论,且随着驾驶员百分位的变化,对座椅舒适性造成影响的参数也在发生变化;最后,对正交实验所得数据进行修正拟合,构建了座椅适宜H点位置预测模型和靠背角度预测模型。

数据-知识混合驱动的压裂球座坐封有效性智能诊断方法

水平井桥塞分段压裂时的桥塞球座坐封有效性实时诊断是其关键环节,若球座坐封失效,将无法正常进行后续作业,目前主要依靠人工观察井口压力变化特征,难以快速准确判识。为此,融合专家经验定性判识和坐封数据特征挖掘定量标注,滑动窗口数据切片形成5792组标签数据,优选井口压力–排量二维输入的长短期记忆神经网络,建立了压裂球座坐封有效性智能诊断模型,并采用欠采样平衡数据集方式提升模型预测精度。结果表明,井口压力呈现显著的陡升—陡降—平缓上升的三阶段特征,若井口压力缺失某个阶段特征,则为坐封失效;井口压力斜率统计值分布范围较大,无法形成明确规则实现准确诊断。采用人工智能技术学习不同井口压力形态的有效/无效坐封数据特征,实现了每秒输出诊断结果,测试集准确率96.8%,验证集准确率84.3%。研究结果为桥塞球座坐封有效性实时自动诊断提供了方法。

高速铁路列车开行方案与票价票额综合优化

为提升高速铁路的运营组织水平和盈利能力,本文提出高铁列车开行方案与票价票额综合优化方法。首先,构建分时客流需求与票价间弹性需求函数,并分析包括出发时段偏差、乘车耗时及票价的旅客广义出行成本,进而采用多项式Logit模型描述分时弹性客流的列车选择行为。在此基础上,以客票总收入与运营总成本之差最大为目标构建三者综合优化模型。其次,利用OD总收益关于列车票价的偏导构造票价方案搜索策略,使票价邻域解和列车开行方案邻域解相适应,并运用Cplex求解对应的最优票额分配方案,设计模拟退火算法求解模型。最后,基于郑西高速铁路进行算例分析,结果表明:在7个不同弹性系数下进行综合优化,旅客出行成功率和列车平均客座率均在90%以上,优化解的列车开行方案、票价方案及票额分配方案均高度匹配;在5组不同规模算例中,三者综合优化的运营净收益相比于固定票价下的开行方案与票额联合优化和固定开行方案下的票价与票额联合优化,分别提高了4.11%~15.25%和3.17%~13.42%,且人均单位里程出行成本亦分别降低了1.69%~4.96%和0.97%~4.35%,表明综合优化更好地提升了高速铁路的运营收益和旅客服务水平。

基于骨架几何位置调整的座椅抗鞭打性能优化

为了减小鞭打试验伤害评估中普遍较高的颈部损伤指标(Neck Injury Criterion,NIC)和上颈部伸张弯矩,基于某汽车座椅的LS-DYNA有限元模型和物理试验结果,首先对其基本结构和后碰撞下的运动响应进行分析,使用多体动力学分析软件(Mathematical Dynamic Model,MADYMO)建立座椅鞭打试验的多体动力学模型.然后,通过伤害机理分析和对座椅主要设计参数的灵敏度分析,确定座椅结构中的主要几何结构参数,并据此建立数值模型.最后,利用多目标优化算法,获得相应的座椅抗鞭打性能优化方案.结果表明,通过调整座椅骨架横梁及头枕位置,提高乘员头部和下颈部运动一致性,使NIC降低58.5%,上颈部伸张弯矩满足最高性能限值.

TDI发动机润滑油挤压高频噪声影响因素试验研究

针对涡轮增压柴油机的运行特点,在半消声试验室进行了发动机加速工况主轴承处润滑油挤压高频噪声的影响因素测试。研究过程基于发动机主轴承座振动测试和曲轴运动轨迹测试,重点分析了润滑系统特征和主轴承结构特征以及曲轴轴承支撑方式对高频挤压噪声的影响。结果表明:润滑油黏度、润滑油含气量、主轴承间隙、主轴颈形状和轴承支撑方式等均对主轴承座异常振动产生影响;当轴承载荷小,轴心偏心距较大,曲轴自转方向与公转方向相反时,主轴承润滑油压力升高,润滑油内的气泡被挤压产生高频的气泡破裂噪声,并伴随主轴承座异常振动;当曲轴运转稳定且轴心轨迹平顺时,主轴承座异常振动对应转速升高,高频噪声不易识别。

全球天然氢勘查开发最新发展态势分析

随着氢气地表异常显示的广泛发现以及对地下氢气成因机制和成藏机理认识的逐步深化,天然氢作为一种清洁能源,因其可能的巨大资源潜力和可再生性,有望成为全球实现能源转型和碳中和的关键能源。通过对全球天然氢勘查开发最新进展的跟踪研究认为:天然氢已成为全球地质与能源领域关注热点,多成因机制下资源调查发现呈点多面广特征,欧美强国持续投入带动全球发展,氢氦地质资源具有“兼探共采”潜力,等等。鉴于我国在天然氢资源发现方面取得的初步进展,以及对成藏条件及有利区带的初步评估,建议我国应尽快开展全国性天然氢资源调查评价工作。