Dynamics and vibration reduction performance of asymmetric tristable nonlinear energy sink

With its complex nonlinear dynamic behavior,the tristable system has shown excellent performance in areas such as energy harvesting and vibration suppression,and has attracted a lot of attention.In this paper,an asymmetric tristable design is proposed to improve the vibration suppression efficiency of nonlinear energy sinks(NESs)for the first time.The proposed asymmetric tristable NES(ATNES)is composed of a pair of oblique springs and a vertical spring.Then,the three stable states,symmetric and asymmetric,can be achieved by the adjustment of the distance and stiffness asymmetry of the oblique springs.The governing equations of a linear oscillator(LO)coupled with the ATNES are derived.The approximate analytical solution to the coupled system is obtained by the harmonic balance method(HBM)and verified numerically.The vibration suppression efficiency of three types of ATNES is compared.The results show that the asymmetric design can improve the efficiency of vibration reduction through comparing the chaotic motion of the NES oscillator between asymmetric steady states.In addition,compared with the symmetrical tristable NES(TNES),the ATNES can effectively control smaller structural vibrations.In other words,the ATNES can effectively solve the threshold problem of TNES failure to weak excitation.Therefore,this paper reveals the vibration reduction mechanism of the ATNES,and provides a pathway to expand the effective excitation amplitude range of the NES.

利用卷积长短期记忆网络预测全球电离层Ne

由于电离层电子密度随时间变化,且空间分布不均匀,对不同频段的无线电波产生延缓和折射,因此电离层电子密度变化是影响短波通信、卫星通信、全球导航卫星系统和其他空间通信质量的一个主要因素,本文对全球电离层电子密度(Number of electron,Ne)的预测工作对短波通信设备三维射线实时追踪定位提供必要条件。本文采用国际电离层参考模型提供的2016年电离层Ne数据,根据数据的三维空间时间序列特征,搭建了自编码器和卷积长短期记忆(Convolutional Long Short-Term Memory Network,Conv LSTM)网络组成的网络结构,在不引入地球自转周期之外任何先验知识的条件下,对Ne数据进行深度学习并实现预测,首先通过实验对比了SGD、Adagrad、Adadelta、Adam、Adamax和Nadam六种优化算法的性能,又对比了三种预测策略的均方根误差(Root Mean Square Error, RMSE),1h-to-1h预测策略的全球平均RMSE为1.0 NEU(最大值的0.4%),1h-to-24h和24h-to-24h预测策略的全球平均RMSE为6.3 NEU(2.6%)。由实验结果得出以下结论,一是Nadam优化算法更适合电离层Ne的深度学习,二是1h预测策略的性能与之前类似的电离层TEC预测工作(RMSE高于1.5 TECU,最大值的1%)相比有竞争力,但预测时间太短且对数据的实时性要求较高,三是两种24h预测策略虽能实现长期预测但性能不理想,要实现三维空间时间序列的长期高精度预测需要进一步改善神经网络、模型结构和预测策略。

黄芪续命汤对阿尔兹海默症脾肾亏虚型患者NE、Hs-CRP、SOD及生活能力的影响

【目的】探讨黄芪续命汤对阿尔兹海默症(Alzheimer’s disease,AD)脾肾亏虚型患者的治疗效果及其可能的作用机制。【方法】将134例AD脾肾亏虚型患者随机分为观察组和对照组,每组各67例。对照组给予西医常规治疗,观察组在对照组的基础上联合黄芪续命汤治疗,疗程为12周。观察2组患者治疗前后中医证候积分、简易精神状态量表(MMSE)评分、阿尔兹海默症评定量表(ADAS-Cog)评分及血清5-羟色胺(5-HT)、去甲肾上腺素(NE)、脑源性神经营养因子(BDNF)、超氧化物歧化酶(SOD)、白细胞介素6(IL-6)、超敏C反应蛋白(Hs-CRP)水平的变化情况,并评价2组患者的临床疗效。【结果】(1)治疗12周后,观察组的总有效率为89.55%(60/67),对照组为71.64%(48/67),组间比较(χ^(2)检验),观察组的疗效明显优于对照组(P<0.05)。(2)治疗后,2组患者的MMSE评分均较治疗前升高(P<0.05),中医证候积分和ADAS-Cog评分均较治疗前降低(P<0.05),且观察组对MMSE评分的升高幅度及对中医证候积分和ADAS-Cog评分的降低幅度均明显优于对照组(P<0.05)。(3)治疗后,2组患者的血清5-HT、NE、BDNF、SOD水平均较治疗前升高(P<0.05),血清IL-6、Hs-CRP水平均较治疗前降低(P<0.05),且观察组对血清5-HT、NE、BDNF、SOD水平的升高幅度及对血清IL-6、Hs-CRP水平的降低幅度均明显优于对照组(P<0.05)。【结论】针对AD脾肾亏虚型患者,在西医常规治疗基础上联合黄芪续命汤治疗,有助于减轻炎症反应,调节氧化应激失衡,促进患者生活能力改善,提高临床疗效。

A geochemical perspective on the genesis of Cenozoic basic volcanism in northeastern Turkey:an overview of metasomatism and heterogeneity of the sub-continental lithospheric mantle in a post-collisional setting

The post-collisional Cenozoic basic volcanic rocks in NE Turkey show temporal variations in whole-rock lithophile element and highly siderophile element(HSE)systematics that are mainly associated with the nature of sub-continental lithospheric mantle(SCLM)sources and parental melt generation.So far,the traditional whole-rock lithophile geochemical data of these basic volcanic rocks have provided important constraints on the nature of SCLM sources.Integrated lithophile element and HSE geochemical data of these basic volcanic rocks also reveal the heterogeneity of the SCLM source,which is principally related to variable metasomatism resulting from previous subduction(s)and post-collisional mantle-crust interactions in an extensional setting.Lithophile element geochemical features suggest that the parental magmas have derived from metasomatized spinel-to garnet-bearing SCLM sources for Eocene and Miocene basic volcanic rocks with subduction signatures whereas originated from spinel-to garnet-bearing SCLM sources for Mio-Pliocene and Plio-Quaternary basaltic volcanic rocks without the subduction signature.Lithophile element and HSE geo-chemistry also reveal that Eocene and Miocene basic vol-canic rocks were affected by more pronounced crustal contamination than the basaltic volcanic rocks of Mio-Pliocene and Quaternary.Furthermore,the integrated lithophile element and HSE compositions of these basic volcanic rocks,together with the regional asymmetric lithospheric delamination model,reveal that the compositional variation(especially due to metasomatism)was significant temporally in the heterogeneity of the SCLM sources from which parental magmas formed during the Cenozoic era.

Q355NE钢特厚板坯凝固过程模拟研究

以(475×2000)mm断面的Q355NE钢特厚板坯为研究对象,通过射钉法和红外测温方法测量凝壳厚度及表面温度,将其作为凝固模型计算结果的验证。使用ProCAST软件进行凝固传热过程模拟,分析了不同拉速、过热度、比水量对铸坯温度场和凝固终点的影响规律。结果表明:与过热度和比水量的影响相比,拉速对其凝固终点、温度场影响较大,拉速每提高0.05 m/min,凝固终点平均后移4.54 m,铸坯完全凝固后的铸坯心部温度升高81℃左右;而比水量每降低10%,铸坯凝固终点后移0.33 m左右;过热度每升高5℃,铸坯凝固终点后移0.38 m左右。

Wind-Vortex-Induced Vibrations of a Deepwater Jacket Pipe and Vibration Suppression Using a Nonlinear Energy Sink

The purpose of this study is to investigate the suppression effect of a nonlinear energy sink(NES)on the wind-vortex-induced pipe vibration and explore the influence of damping,stiffness,and NES installation position on the suppression effect.In this work,the wind-vortex-induced vibration of an elastic pipe of a deepwater jacket was studied,and vibrations were suppressed by using an NES.A van der Pol wake oscillator was used to simulate vortex-induced force,and the dynamic equation of the pipe considering the NES was established.The Galerkin method was applied to discretize the motion equation,and the vortex-induced vibration(VIV)of the pipe at reduced wind speeds was numerically analyzed.The novelty of this research is that particle swarm optimization was used to optimize the parameters of the NES to improve vibration suppression.The influence of the installation position,nonlinear stiffness,and damping parameters of the NES on vibration suppression was analyzed.Results showed that the optimized parameter combinations of the NES can effectively reduce wind-vortex-induced pipe vibration.The installation position of the NES had a significant effect on vibration suppression,and the midpoint of the pipe was the optimal NES installation position.An increase in stiffness or a 10% decrease in damping may cause vibration suppression failure.The results of this study provide some guidance for VIV suppression in deepwater jacket pipes.

Dynamic performance and parameter optimization of a half-vehicle system coupled with an inerter-based X-structure nonlinear energy sink

Inspired by the demand of improving the riding comfort and meeting the lightweight design of the vehicle, an inerter-based X-structure nonlinear energy sink(IXNES) is proposed and applied in the half-vehicle system to enhance the dynamic performance. The X-structure is used as a mechanism to realize the nonlinear stiffness characteristic of the NES, which can realize the flexibility, adjustability, high efficiency, and easy operation of nonlinear stiffness, and is convenient to apply in the vehicle suspension, and the inerter is applied to replacing the mass of the NES based on the mass amplification characteristic. The dynamic model of the half-vehicle system coupled with the IX-NES is established with the Lagrange theory, and the harmonic balance method(HBM) and the pseudo-arc-length method(PALM) are used to obtain the dynamic response under road harmonic excitation. The corresponding dynamic performance under road harmonic and random excitation is evaluated by six performance indices, and compared with that of the original half-vehicle system to show the benefits of the IX-NES. Furthermore, the structural parameters of the IX-NES are optimized with the genetic algorithm. The results show that for road harmonic and random excitation, using the IX-NES can greatly reduce the resonance peaks and root mean square(RMS) values of the front and rear suspension deflections and the front and rear dynamic tire loads, while the resonance peaks and RMS values of the vehicle body vertical and pitching accelerations are slightly larger.When the structural parameters of the IX-NES are optimized, the vehicle body vertical and pitching accelerations of the half-vehicle system could reduce by 2.41% and 1.16%,respectively, and the other dynamic performance indices are within the reasonable ranges.Thus, the IX-NES combines the advantages of the inerter, X-structure, and NES, which improves the dynamic performance of the half-vehicle system and provides an effective option for vibration attenuation in the vehicle engineering.

Identification of banana leaf disease based on KVA and GR-ARNet

Banana is a significant crop,and three banana leaf diseases,including Sigatoka,Cordana and Pestalotiopsis,have the potential to have a serious impact on banana production.Existing studies are insufficient to provide a reliable method for accurately identifying banana leaf diseases.Therefore,this paper proposes a novel method to identify banana leaf diseases.First,a new algorithm called K-scale VisuShrink algorithm(KVA)is proposed to denoise banana leaf images.The proposed algorithm introduces a new decomposition scale K based on the semi-soft and middle course thresholds,the ideal threshold solution is obtained and substituted with the newly established threshold function to obtain a less noisy banana leaf image.Then,this paper proposes a novel network for image identification called Ghost ResNeSt-Attention RReLU-Swish Net(GR-ARNet)based on Resnet50.In this,the Ghost Module is implemented to improve the network's effectiveness in extracting deep feature information on banana leaf diseases and the identification speed;the ResNeSt Module adjusts the weight of each channel,increasing the ability of banana disease feature extraction and effectively reducing the error rate of similar disease identification;the model's computational speed is increased using the hybrid activation function of RReLU and Swish.Our model achieves an average accuracy of 96.98%and a precision of 89.31%applied to 13,021 images,demonstrating that the proposed method can effectively identify banana leaf diseases.

CO_(2) mineralization by typical industrial solid wastes for preparing ultrafine CaCO_(3): A review

Mineral carbonation is a promising CO_(2) sequestration strategy that can utilize industrial wastes to convert CO_(2) into high-value CaCO_(3).This review summarizes the advancements in CO_(2) mineralization using typical industrial wastes to prepare ultrafine CaCO_(3).This work surveys the mechanisms of CO_(2) mineralization using these wastes and its capacities to synthesize CaCO_(3),evaluates the effects of carbonation pathways and operating parameters on the preparation of CaCO_(3),analyzes the current industrial application status and economics of this technology.Due to the large amount of impurities in solid wastes,the purity of CaCO_(3) prepared by indirect methods is greater than that prepared by direct methods.Crystalline CaCO_(3) includes three polymorphs.The polymorph of CaCO_(3) synthesized by carbonation process is determined the combined effects of various factors.These parameters essentially impact the nucleation and growth of CaCO_(3) by altering the CO_(2) supersaturation in the reaction system and the surface energy of CaCO_(3) grains.Increasing the initial pH of the solution and the CO_(2)flow rate favors the formation of vaterite,but calcite is formed under excessively high pH.Vaterite formation is favored at lower temperatures and residence time.With increased temperature and prolonged residence time,it passes through aragonite metastable phase and eventually transforms into calcite.Moreover,polymorph modifiers can decrease the surface energy of CaCO_(3) grains,facilitating the synthesis of vaterite.However,the large-scale application of this technology still faces many problems,including high costs,high energy consumption,low calcium leaching rate,low carbonation efficiency,and low product yield.Therefore,it is necessary to investigate ways to accelerate carbonation,optimize operating parameters,develop cost-effective agents,and understand the kinetics of CaCO_(3) nucleation and crystallization to obtain products with specific crystal forms.Furthermore,more studies on life cycle assessment(LCA)should be conducted to fully confirm the feasibility of the developed technologies.

NeTrainSim:a network-level simulator for modeling freight train longitudinal motion and energy consumption

Although train modeling research is vast, most available simulation tools are confined to city-or trip-scale analysis, primarily offering micro-level simulations of network segments. This paper addresses this void by developing the Ne Train Sim simulator for heavy long-haul freight trains on a network of multiple intersecting tracks. The main objective of this simulator is to enable a comprehensive analysis of energy consumption and the associated carbon footprint for the entire train system. Four case studies were conducted to demonstrate the simulator's performance. The first case study validates the model by comparing Ne Train Sim output to empirical trajectory data. The results demonstrate that the simulated trajectory is precise enough to estimate the train energy consumption and carbon dioxide emissions. The second application demonstrates the train-following model considering six trains following each other. The results showcase the model ability to maintain safefollowing distances between successive trains. The next study highlights the simulator's ability to resolve train conflicts for different scenarios. Finally, the suitability of the Ne Train Sim for modeling realistic railroad networks is verified through the modeling of the entire US network and comparing alternative powertrains on the fleet energy consumption.

路博润:扩充TPU生产线、成立亚太区高性能膜品创新中心、推出“ESTANE TPU赋能生态系统”

路博润公司近日宣布一系列加速拓展本地化生产和创新能力的重要举措,旨在进一步深化热塑性聚氨酯(TPU)业务本土发展布局。这包括扩充上海工厂TPU生产线、成立亚太区高性能膜品创新中心以及推出“ESTANE TPU赋能生态系统”。这些举措不仅凸显了路博润在TPU领域的雄厚实力,更彰显了对中国市场持续增长的坚定信心,以及对与行业共同成长的长期承诺。

1500MW燃机电站配套NE余热锅炉大型模块吊装工艺探讨

通过对国际上1500MW燃机电站配套NE余热锅炉大模块吊装工艺研究与实践,总结经验与不足,改进该类型余热锅炉大模块的吊装工艺,对未来类似项目提供积极参考。

路博润面向全球漆面保护膜市场推出ESTANE TPU赋能生态系统

前不久,路博润面向漆面保护膜(PPF)行业推出ESTANE TPU赋能生态系统,旨在帮助使用100% ESTANE TPU材料生产热塑性聚氨酯(TPU)基膜或PPF产品的制造商和品牌商们推广其产品的高品质和性能。路博润的ESTANE TPU在PPF行业拥有超过30年的应用经验,赢得了行业性能标杆的声誉。路博润的赋能生态系统为加入该系统的合作企业提供了源头材料的授权认证方式。

TDM网主用汇聚节点NE20故障案例分析

NE20作为各地区局广泛使用的重要路由汇聚设备,需要满足长期稳定运行的要求,本文结合湖北空管分局TDM网主用汇聚节点NE20发生的故障,TDM网承载的甚高频、雷达、ADS-B和甚高频监控业务出现短暂中断的现象,通过详细的排查过程,原因分析和改进措施,成功定位故障源头并提出有效的解决方案。

养血清脑颗粒联合艾司西酞普兰治疗卒中后抑郁的临床效果及对血清5-HT和NE水平影响

目的:研究养血清脑颗粒联合艾司西酞普兰治疗卒中后抑郁(Post-stroke depression,PSD)的临床效果及对血清5-羟色胺(5-Hydroxy tryptamine,5-HT)和去甲肾上腺素(Norepinephrine,NE)水平影响。方法:选取我院收治的卒中后抑郁患者400例。随机分为2组各200例。对照组给予艾司西酞普兰,治疗组在此基础上联用养血清脑颗粒。分析对比两组的疗效、汉密顿抑郁量表(Hamilton depression scale,HAMD)评分、简易精神状态检查量表(Mini-mental state examination,MMSE)评分和Barthel指数评分及血清5-HT和NE水平。结果:治疗后,治疗组总有效率显著高于对照组(P<0.05)。治疗后,两组HAMD各条目评分均较治疗前显著降低(P<0.05);并且治疗组降低程度较大(P<0.05)。治疗后,两组MMSE评分和Barthel指数评分及血清5-HT和NE水平均显著升高(P<0.05);且治疗组升高程度较大(P<0.05)。结论:采用养血清脑颗粒联合艾司西酞普兰治疗PSD可提高临床疗效,能够改善认知功能。

颐脑解郁方联合五行音乐对轻中度卒中后抑郁患者血清5-HT、NE的影响研究

【目的】探讨颐脑解郁方联合五行音乐对轻中度卒中后抑郁(PSD)患者的治疗效果及对血清5-羟色胺(5-HT)、去甲肾上腺素(NE)的作用。【方法】将120例轻中度PSD患者随机分为西药组、颐脑解郁方组、五行音乐组、联合组4组,每组各30例,各组患者在常规脑卒中康复治疗基础上,分别给予盐酸氟西汀胶囊、颐脑解郁方、五行音乐、颐脑解郁汤联合五行音乐治疗,疗程为4周。观察各组患者治疗前后汉密尔顿抑郁量表(HAMD)评分、美国国立卫生研究院卒中量表(NIHSS)神经功能评分、改良Rankin量表(mRS)评分、Barthel指数(BI)评分及血清5-HT、NE水平的变化情况,并评价各组患者的临床疗效。【结果】(1)治疗4周后,西药组、五行音乐组、颐脑解郁方组、联合组的总有效率分别为86.67%(26/30)、76.67%(23/30)、73.33%(22/30)、93.33%(28/30);组间比较,联合组的总体疗效优于其他3组(P<0.05),西药组优于五行音乐组和颐脑解郁方组(P<0.05),而五行音乐组与颐脑解郁方组比较,差异无统计学意义(P>0.05)。(2)治疗后,各组患者的HAMD评分、NIHSS评分、m RS评分和BI评分均较治疗前明显改善(P<0.05);组间比较,联合组对各项量表评分的改善作用优于其他3组,西药组优于五行音乐组和颐脑解郁方组,五行音乐组又优于颐脑解郁方组,差异均有统计学意义(P<0.05)。(3)治疗后,各组患者血清5-HT、NE水平均较治疗前明显升高(P<0.05);组间比较,联合组的血清5-HT、NE水平高于其他3组,西药组高于五行音乐组和颐脑解郁方组,五行音乐组又高于颐脑解郁方组,差异均有统计学意义(P<0.05)。【结论】颐脑解郁方联合五行音乐疗法治疗轻中度PSD患者疗效确切,可有效调控血清5-HT、NE水平,改善患者抑郁症状,促进患者神经功能恢复,改善患者预后,提高患者生活质量。

基于构造物理模拟的塔中北坡NE向走滑断裂形成机理

为了揭示塔中北坡NE向走滑断裂的形成机制,本文在前人研究的基础上,利用相似分析原理,设计了构造物理模拟实验平台,完成了3组构造物理模拟对比实验,模拟了塔中北坡NE向走滑断裂的形成演化过程,分析了塔中北坡NE向走滑断裂的形成机制。结果表明:塔中北坡NE向走滑断裂受控于先存的基底断裂以及上奥陶统厚层泥岩的调节作用,在周缘构造活动的作用下形成;塔中地区NE向走滑断裂经历了形成期和复活期两个阶段,先后受到SW方向与SE方向作用力挤压。

新型非对称惯容NES减震控制性能研究

为提高控制装置的减震性能及减小附加阻尼器的质量,基于非对称非线性能量阱(nonlinear energy sink,NES)提出一种附加惯容器的新型控制装置——非对称惯容NES。根据非对称惯容NES系统的工作原理推导出运动方程;在脉冲型荷载作用下进行控制参数数值优化,分析非对称惯容NES的能量鲁棒性和频率鲁棒性。分析地震作用下结构与控制装置响应,研究主体结构刚度变化前后的控制性能。应用数值小波变换对体系的地震响应时程进行功率谱分析,从能量的角度研究控制装置的减振机理。研究结果表明,非对称惯容NES具有极强的能量鲁棒性和频率鲁棒性,在地震作用过程中能有效减小顶层加速度峰值且所需行程更小,能在更广频域内与主体结构发生共振,因而其减震效率更高。非对称惯容NES减震控制性能与已有的非对称NES相当甚至更优,并能够减小40%阻尼器质量,在实际应用中具有更广阔的前景。

Φ800 mm圆坯Q355NE凝固传热数值模拟和工艺实践

以钢厂断面尺寸为Φ800 mm圆坯Q355NE为研究对象,建立大圆坯传热模型,在不采用结晶器电磁搅拌的条件下,研究拉速和过热度对凝固过程的影响规律。结果表明:拉速对坯壳厚度、凝固终点位置和中心固相率的影响高于过热度,拉速每增加0.02 m·min^(-1),凝固终点后移2.6 m左右;过热度升高10℃,凝固终点后移0.21 m左右。实际生产中,二冷比水量0.18 L·kg^(-1)、过热度25℃、拉速0.14 m·min^(-1)时,出结晶器坯壳厚度超过43 mm,末端电磁搅拌充分发挥作用,铸坯中心疏松和中心缩孔较结晶器电磁搅拌(300 A/1.5 Hz)、二冷比水量0.18 L·kg^(-1)、过热度25℃、拉速0.16 m·min^(-1)工艺有所改善。

激活后的NEG薄膜在氖气保护下的应用研究

NEG薄膜目前已成为新一代同步辐射光源储存环真空室表面处理的主要手段,HALF光源拟采用镀Ti-Zr-V NEG薄膜的方式以满足储存环真空度的设计要求。在一些情况下,需要打开真空室以更换某些故障件或安装插入件等,这将使NEG薄膜暴露大气,严重损伤薄膜的吸气性能及使用寿命,此外也需要数周时间使真空度恢复到原有水平。因此采取向真空室充入Ne气的方法能在一定程度上保护激活后的NEG薄膜,从而避免再次激活薄膜以延长使用寿命和节省时间,另外进行了充入N_(2)的对比实验。结果表明,充入Ne气后,真空度恢复后能满足静态真空度的要求,无需激活,从而延长NEG薄膜的使用寿命并且节省时间。而充入N_(2)后,真空度恢复后达不到静态真空度的要求。但通过低温激活,NEG薄膜均能恢复一定活性并达到静态真空度要求。相对于N_(2),在Ne气保护作用下真空度恢复的更好。通过对残余气体的分析,发现低温激活前后Ne的含量均极低,对束流的稳定性不会产生影响,进一步证明了充入Ne气的可行性。