基于DDS Ramped FSK技术的机车信号测试系统设计

为了解决目前通用机车信号环线发送器系统复杂、价格贵,便携式机车信号发送器精度和可靠性低等问题,采用DDS Ramped FSK技术设计了一种机车信号测试系统,该系统可模拟18信息、UM71和ZPW2000移频轨道电路的信号,通过上位机控制该系统输出不同的载频和低频编码Ramped FSK信号,减小了对邻近信号设备的干扰,便于车载设备解调。该系统结构简单,输出信号稳定可靠。

Radiation Effect on Natural Convection Near a Vertical Plate Embedded in Porous Medium with Ramped Wall Temperature

Radiation effect on the natural convection flow of an optically thin viscous incompressible fluid near a vertical plate with ramped wall temperature in a porous medium has been studied. The exact solution of momentum and energy equations is obtained by the use of Laplace transform technique. The variations in fluid velocity and temperature are shown graphically whereas the numerical values of shear stress and the rate of heat transfer at the wall are presented in tabular form for various values of flow parameters. The results show that the fluid velocity increases with increase in Grashof number, Darcy number and time parameters whereas the fluid velocity decreases with increase in the radiation parameter and Prandtl number for ramped temperature as well as isothermal wall temperature. It is found that an increase in radiation parameter leads to rise the temperature for both ramped wall temperature as well as isothermal wall temperature. Further, it is found that an increase in Prandtl number leads to fall the temperature for both ramped wall temperature as well as isothermal wall temperature. The shear stress at the wall decreases with increases in either Prandtl number or porosity parameter while the result shows reverse in the case of radiation parameter. Finally, the rate of heat transfer is increased with increases in the radiation parameter for both ramped wall temperature as well as isothermal wall temperature.

Mathematical Modelling of Mass Transfer and Free Convection Current Effects on Unsteady Viscous Flow with Ramped Wall Temperature

An exact analysis of the flow of an incompressible viscous fluid past an infinite vertical plate is conducted taking into account the presence of foreign mass or constant mass flux and ramped wall temperature. The dimensionless governing coupled linear partial differential equations are solved using the Laplace transform technique. Two different solutions for the fluid velocity are obtained–one valid for the fluids of Schmidt numbers different from unity, and the other for which the Schmidt number is unity. The effects of Prandtl number (Pr), Schmidt number (Sc), time (t) and mass to thermal buoyancy ratio parameter (N) for both aiding and opposing buoyancy effects on the velocity and skin-friction are studied. Also, the heat and mass transfer effects on the flow near a ramped temperature plate have been compared with the flow near a plate with constant temperature.

Radiation Effects on Free Convection Flow Neara Vertical Plate with Ramped Wall Temperature

The effect of radiation on the unsteady natural convection flow past an infinite vertical plate is presented, wherein the plate temperature is a ramped one. The fluid considered here is a gray, absorbing/emitting but a non-scattering medium. The influence of the various parameters entering into the problem on the velocity field, temperature field, skin friction and Nusselt number is studied.

Natural Convection Flow of Heat Generating/Absorbing Fluid near a Vertical Plate with Ramped Temperature

This study considers a theoretical analysis of natural convection flow of heat generating/absorbing fluid near an infinite vertical plate with ramped temperature. It is assumed that the bounding plate has a ramped temperature profile. Exact solutions of energy and momentum equations are obtained using the Laplacetransform techniques. Solutions are obtained for different values of the Prandtl number (Pr) and the heat sink parameter (S). Results of the ramped and isothermal temperature and velocity as well as Nusselt number and skin friction have been compared and presented with the help of graphs.

膝关节Ramp损伤的研究进展

Ramp损伤(RL)是膝关节内侧半月板后角与关节囊移行区域损伤,常见于慢性前交叉韧带(ACL)损伤患者,也可孤立发生。Ramp区对维持膝关节功能及保护ACL重建移植物有重要作用,膝关节MRI在诊断RL上敏感度中等但特异度较高,关节镜是诊断的金标准。对RL的认识目前处于一个“再认识”的阶段,对其最佳的处理方式是近年来研究的热点。本文结合近年来研究现状,从RL的流行病学、解剖学、产生机制、分型、诊断以及手术治疗方面进行综述,以期为RL的研究及诊治提供参考。

前交叉韧带断裂合并内侧半月板Ramp区损伤的临床疗效分析

目的探讨前交叉韧带(anterior cruciate ligament,ACL)断裂合并内侧半月板后角Ramp区损伤同期治疗的临床疗效,对ACL断裂合并内侧半月板Ramp区损伤患者的手术治疗提供一些参考。方法2018年3月至2020年8月佛山市第一人民医院关节骨外科收治23例ACL合并内侧Ramp区损伤患者,其中男15例,女8例;年龄19~64岁,平均(36.4±13.6)岁。接受关节镜下韧带重建同期行内侧半月板后角Ramp区修复手术,术后佩戴可调节膝关节角度的铰链支具3个月。术后3 d内行膝关节正侧位X线检查及CT骨隧道重建,末次随访时以前抽屉试验、Lachman试验评估膝关节稳定性及韧带松弛度,以2000国际膝关节评分委员会(international knee documentation committee,IKDC)膝关节评分、Lysholm膝关节评分和Tegner膝关节运动评分评估膝关节活动度及功能。结果23例均获随访,随访时间24~48个月,平均(34.0±8.0)个月。末次随访时ACL断裂合并Ramp区损伤患者2000 IKDC膝关节主观评分、Lysholm膝关节评分、Tegner膝关节运动评分分别从术前的(70.3±4.9)分、(58.0±7.0)分、(4.3±0.8)分提高到术后的(85.0±5.2)分、(81.6±6.1)分、(7.3±1.4)分,手术前后评分比较差异有统计学意义。23例患者患侧膝关节活动度平均(135.0±3.4)°,无活动受限。术后患者膝关节正侧位X线片示对线对位良好,未出现畸形,膝关节CT重建显示股骨及胫骨隧道位置良好,锚钉位置良好、固定牢固,MRI冠状面、矢状面、横断面序列未发现半月板后角Ⅲ级信号。23例患者随访期间均未发生韧带再损伤,未因半月板再次损伤而行关节镜手术。结论对ACL断裂合并内侧半月板Ramp区损伤患者,膝关节镜ACL重建同期行内侧半月板Ramp区修补术,术后膝关节稳定性、活动及功能明显改善,可进一步减少膝关节损伤,获得比较满意的活动度及关节功能。

Heat and mass transfer in magnetohydrodynamic(MHD)Casson fluid flow past over an oscillating vertical plate embedded in porous medium with ramped wall temperature

The present paper is concerned with the study of flow,heat and mass transfer characteristics in the unsteady natural convective magneto hydrodynamics Casson fluid flow past over an oscillating vertical plate.The governing partial differential equations are solved analytically using Laplace transform technique and numerically using Matlab software.Expressions of skin friction,Nusselt number and Sherwood number are obtained.The features of the fluid flow,heat and mass transfer characteristics are analyzed by plotting graphs and the physical aspects are discussed in detail.

Platform Evolution in an Oligo-Miocene Back-arc Basin:An Example from the Central Iran Basin

The Qom Formation is the most important hydrocarbon reservoir target in Central Iran.The Qom platform developed in a back-arc basin during the Oligo-Miocene due to the closing of the Tethyan Seaway.This formation consists of a variety of carbonate and non-carbonate facies deposited on a platform ranging from supratidal to basin.A combination of tectonic and eustatic events led to some lateral and vertical facies variations in the study area.Six third-order depositional sequences and related surfaces were identified regarding vertical facies changes in the studied sections of this Oligo-Miocene succession.According to all results and data,this succession was initially deposited during the Chattian upon a distally steepened ramp of siliciclastic-carbonate composition,including the Bouma sequence.Then,from the late Chattian to the Aquitanian,the platform changed into a homoclinal carbonate ramp with a gentle profile.With respect to tectonic activity,this phase was a calm period during the deposition of the Qom Formation.Finally,a drowned carbonate platform and a rimmed shelf emerged during the Burdigalian,terminated by the continental deposits of the Upper Red Formation.Regarding all geological characteristics,three main tectono-eustatic evolutionary phases have been recognized in the Qom back-arcbasin.

Application of Connected Truck Data to Evaluate Spatiotemporal Impact of Rest Area Closures on Ramp Parking

Ensuring adequate access to truck parking is critical to the safe and efficient movement of freight traffic. There are strict federal guidelines for commercial truck driver rest periods. Rest areas and private truck stops are the only places for the trucks to stop legally and safely. In locations without sufficient parking areas, trucks often park on interstate ramps, which create safety risks for other interstate motorists. Historically, agencies have employed costly and time intensive manual counting methods, camera surveillance, and driver surveys to assess truck parking. Connected truck data, available in near real-time, offers an efficient alternative to practitioners to assess truck parking patterns and identify areas where there may be insufficient safe parking spaces. This paper presents a case study of interstate I-70 in east central Indiana and documents the observed spatiotemporal impacts of a rest area closure on truck parking on nearby interstate ramps. Results showed that there was a 28% increase in parking on ramps during the rest area closure. Analysis also found that ramps closest to the rest area were most impacted by the closure, seeing a rise in truck parking sessions as high as 2.7 times. Parking duration on the ramps during rest area closure also increased drastically. Although it was expected that this would result in increased parking by trucks on adjacent ramps, this before, during, after scenario provided an ideal scenario to evaluate the robustness of these techniques to assess changing parking characteristics of long-haul commercial trucks. The data analytics and visualization tools presented in this study are scalable nationwide and will aid stakeholders in informed data-driven decision making when allocating resources towards improving the nations commercial vehicle parking infrastructure.

基于似然BP算法的区域供电能效差异变化趋势预测方法

采用目前方法预测区域供电能效差异变化趋势时,存在误差率高、预测值与实际值差距大及预测模型复杂程度高的问题。提出基于似然BP算法的区域供电能效差异变化趋势预测方法。利用RAMP重构具有稀疏噪声的电能数据,并将处理后的无干扰电能原始数据投入到神经网络中,利用似然BP算法对数据样本进行编码、选择、交叉和变异,最终构建预测模型,并运用预测模型完成区域供电能效差异变化趋势的预测。实验结果表明,所提方法误差率低、预测值与实际值差距小、预测模型复杂程度低。

Design and Engineering of Urban Interchange Ramp Bridge Structure

This paper analyzes the structural design of an urban interchange ramp bridge from four aspects,which are the superstructure,pier structure,foundation structure,and deck structure design to summarize the structural design ideas of this urban interchange ramp bridge,which can be used as a reference for future construction of the same bridge.

A Review of the Key Points in the Design of Small-Radius Curved Ramp Bridges

This article explores the fundamentals of small-radius curved ramp bridges.It covers the selection of box girder spans,support methods,and forms,along with design optimization techniques for this type of bridge structure.The purpose of this paper is to provide robust support for enhancing the design quality of these bridges and ensuring their efficacy in real-world applications.

基于CNN-SVM的飞机EHA故障诊断算法研究

针对飞机电动静液作动器(electro-hydrostatic actuator,EHA)系统集成度高、工况复杂、故障种类多的特点,为了对其典型故障进行有效诊断,提出一种基于卷积神经网络(convolutional neural networks,CNN)和支持向量机(support vector machine,SVM)的故障诊断算法。使用CNN对故障数据进行自适应特征提取,再利用SVM对CNN全连接层输出进行分类。为提高SVM分类性能,使用带动态惯性权重的自适应粒子群优化算法(dynamic inertia weight adaptive particle swarm optimization,IWAPSO)实现对SVM参数的优化选择。引入Ramp损失函数降低SVM的噪声敏感性。结果表明:经过参数优化后的SVM准确率比标准SVM提升了12.6%,比传统CNN方法提升了17.3%;当使用含噪声信号的测试集时,基于Ramp损失函数的SVM表现出了更好的鲁棒性。

前交叉韧带断裂合并半月板ramp区损伤的临床治疗经验

目的分享和探讨前交叉韧带断裂合并半月板ramp区损伤在关节镜下的临床经验与疗效。方法56例前交叉韧带断裂合并半月板ramp区损伤的患者,按手术方式分为2组,对照组29例行膝关节镜下可调节袢-自体腘绳肌腱单束重建术,观察组27例在其基础上采用膝关节镜下可调节袢-自体腘绳肌腱单束重建术+半月板ramp区缝合修复术。术后随访以IKDC、Lysholm、步态测试仪,关节稳定测定为膝关节功能恢复的主观评价指标。结果56例平均随访18.7个月,平均年龄26.3岁,未发生感染及关节僵硬等并发症。观察组半月板临床愈合率为92.59%,明显高于对照组的68.96%,术前2组患者IKDC、Lysholm评分差异无显著性(P>0.05),术后6个月观察组膝关节IKDC、Lysholm评分均明显优于对照组(P<0.05)。结论膝关节镜下同期行可调节袢-自体腘绳肌腱单束重建术+半月板ramp区缝合修复术更有利于半月板愈合,能够获得更好的膝关节稳定性,值得临床推广。

MRI成像在评价膝关节内侧半月板Ramp损伤稳定性中的价值

Ramp损伤作为前交叉韧带撕裂的继发性损伤之一,损伤区域能否被及时识别和修复将对前交叉韧带重建患者的手术愈后效果会产生重要影响^([1-2])。由于解剖位置的特殊性,Ramp损伤在传统的前路或前外路关节镜手术中的漏诊率较高^([3]),而膝关节MRI成像凭借着对软组织及纤维结构的显示具有高分辨力优势.

磁共振成像诊断前交叉韧带撕裂伴Ramp损伤的价值

目的探讨前交叉韧带(ACL)撕裂患者术前磁共振成像(MRI)诊断Ramp损伤的价值,以期为临床治疗提供参考。方法选取2019年6月—2022年7月在四川省骨科医院治疗的ACL撕裂患者126例为研究对象,给予MRI和关节镜检查。比较分析MRI诊断Ramp损伤的价值,同时分析合并和未合并Ramp损伤患者临床资料、影像资料差异,尝试明确ACL撕裂合并Ramp损伤的影响因素。结果MRI诊断与关节镜检查一致性Kappa值为0.527,P<0.001,一致性一般。MRI诊断ACL合并Ramp损伤的灵敏性、特异性、准确性、阳性预测值和阴性预测值分别为45.00%、98.11%、89.68%、82.82%和90.43%。合并Ramp损伤组病程≥6周患者比例高于未合并Ramp损伤组患者(P<0.05);2组患者性别构成、年龄、身体质量指数等比较,差异无统计学意义(P>0.05)。合并Ramp损伤组内侧半月板后角与关节囊连接处出现线样液性高信号、内侧半月板后角边缘出现纵行撕裂、胫骨前移、股骨内侧髁骨挫伤、ACL完全撕裂患者所占比例高于未合并Ramp损伤组患者,差异均有统计学意义(P<0.05)。多因素逐步Logistic回归分析结果显示:病程、内侧半月板后角与关节囊连接处出现线样液性高信号、内侧半月板后角边缘出现纵行撕裂、胫骨前移、股骨内侧髁骨挫伤是ACL撕裂患者发生Ramp损伤的影响因素(P<0.05)。结论MRI诊断ACL撕裂合并Ramp损伤的灵敏性较低,但特异性较高。ACL撕裂合并Ramp损伤受病程、内侧半月板后角与关节囊连接处出现线样液性高信号、内侧半月板后角边缘出现纵行撕裂、胫骨前移、股骨内侧髁骨挫伤的影响。本研究基本复制了临床情况,具有实用价值。

Reconstruction of the Yangtze Ramp during Floian to Darriwilian(Ordovician)in South China:Its Morphology,Controlling Factors and Significances

A robust stratigraphic framework and a coherent depositional ramp model for the Zitai,Dawan,Meitan and Ningkuo formations of Floian–Darriwilian age(Early–Middle Ordovician)in the Yangtze(Daoba,Xiangshuidong,Daling,Gudongkou and Honghuayuan sections)and Jiangnan regions(Nanba section)was created based on lithofacies and major element analysis.Three siliciclastic(LF1–3)and six carbonate(LF4–9)lithofacies are recognized representing sediments that were deposited in mixed siliciclastic and carbonate ramp environment.The intensity of mixed sedimentation and terrigenous input were evaluated using the elemental proxies Intensity of Mixed sedimentation(IM)and Aluminum Accumulation Rate(Al AR),as well as their mean values during certain time intervals.Mixed sediments are most well-developed along the marginal Yangtze region,strongly impacted by recurrent influx of westerly derived terrigenous materials in response to global eustatic changes and regional tectonic movements,shaping the gently southeast-dipping morphology.Regular terrigenous influx resulted in periods of enhanced primary productivity on the Yangtze Ramp as evidenced by matching biodiversity peaks in planktonic organisms,i.e.,chitinozoans and acritarchs.Brachiopods and other shelly fauna were also able to proliferate as new niches developed along the gently dipping ramp floor with substrate changes.The biodiversification patterns suggest that terrigenous influx controlled in part by regional tectonics played a more important role than previously thought in the development of Great Ordovician Biodiversification Event in South China.

前交叉韧带断裂合并内、外侧半月板后部复杂损伤的修复重建

目的:探讨前交叉韧带(anterior cruciate ligament,ACL)断裂合并内、外侧半月板后部复杂损伤修复的方法和疗效。方法:回顾性分析2016年10月~2019年10月本院收治的33例接受ACL重建手术的患者,且术中同时重建修复了外侧半月板后根部(LMPR)损伤及内侧半月板RAMP区(RAMP)损伤。根据术前患膝的轴移分度分为两组:低度轴移组25例,其中男18例、女7例,年龄16~41岁(平均26.6±8.19岁);高度轴移组8例,其中男6例、女2例,年龄17~43岁(平均25.4±9.64岁)。记录两组的手术时间、术后并发症情况,术前、术后1年、术后2年的Lysholm膝关节评分、国际膝关节文献委员会(IKDC)评分以及术后2年的轴移分度和患膝MRI,评估ACL及内、外侧半月板后部损伤的愈合情况。结果:所有患者均获随访24~60个月(平均32.8±16.6个月)。手术时间为98±21.4 min。两组术后1年、术后2年的Lysholm膝关节评分、IKDC评分均显著优于术前(P均<0.001)。术前轴移分度:低度轴移组25例(1度15例,2度10例),高度轴移组8例(3度);术后2年轴移分度:低度轴移组1度降为0度15例、2度降为0度3例、2度降为1度7例,高度轴移组3度降为0度1例、3度降为1度4例、3度降为2度3例;术后2年低度轴移组MRI评估RAMP损伤愈合率为92%,LMPR损伤愈合率为88%;高度轴移组RAMP损伤愈合率为75%,LMPR损伤愈合率为75%。并发症情况:无手术部位感染及血管神经损伤情况,下肢肌间静脉血栓形成5例,经3月抗凝治疗后好转,无肺栓塞或死亡发生。结论:针对ACL断裂同时合并RAMP及LMPR损伤的患者,可通过重建ACL的同时修复内、外侧半月板后部复杂撕裂,可恢复膝关节稳定性,改善轴移分度,提升功能评分,达到满意的临床疗效。但手术时间相对较长,且操作复杂,需配合专用修复工具,故需要重视术前的评估和准备工作。

全承载式客车车身结构拓扑优化设计

以全承载式低地板公交车车身结构为研究对象,在水平弯曲工况下,以应力为约束条件,建立结构质量最小为目标函数的拓扑优化模型。通过变密度法对客车车身结构进行拓扑优化计算,得出了车身载荷的传递路径。为了验证拓扑优化具有可靠性,根据优化结果布置材料,设计出一款车身骨架结构,在水平弯曲工况下对该车身结构进行有限元静力分析,得出结构的最大应力和变形量。经过比较,车身的强度、刚度满足设计要求,说明了该拓扑优化结构具有可行性。