基于组合模型的浙江省GDP预测研究

区域 GDP 的发展趋势是高速公路规划和建设的重要参考依据。 本文基于浙江省 197 8.至 201 9.年的 GDP 数据, 分析数据特性, 构建预测模型, 掌握发展规律。 首先, 将 GDP 数据转化为时间序列, 建立 ARIMA (2, 2, 0) 模型 ; 其次, 将 GDP 数据以滑动窗口的方式生成输入矩阵, 建立 BP 神经网络模型 ; 最后, 利用 ARIMA 分析 GDP 时序的线性部分, 利用 BP 神经网络分析 GDP 时序的非线性部分, 建立组合模型。 通过计算相对误差比较模型的预测效果, 三个模型的平均相对误差分别是 6.和 6.结果表明, 组合模型的平均相对误差最小, 预测效果最好     

级配曲线走向与沥青混凝空隙率关系的研究

基于11组不同走向矿料级配的沥青混合料试验数据,对沥青混合料空隙率随级配曲线走向改变的变化规律进行了研究,分析了沥青混合料空隙率对级配变化的敏感程度．随着细集料由偏细的上限级配变化到偏粗的下限级配,沥青混合料空隙率逐渐变大;粗集料采用中间级配时空隙率最小,采用上限级配时空隙率最大．秩和检验表明：粗、细集料及4．75mm通过率的变化均对沥青混合料空隙率产生影响．其中,细集料级配的变化是导致沥青混合料空隙率变化的最显著因素．关键词：级配曲线走向;沥青混合料;空隙率;秩和检验     

基于OpenCV和DirectShow的交通运动目标检测算法研究

针对运动目标的自动检测问题,提出了一种改进的背景差分算法,采用背景图像多帧平均进行背景的获取和更新,进一步检测出运动车辆轮廓。使用VC++6.0作为开发环境,结合DirectShow视频处理库和OpenCV图像处理库进行编程实现。通过对两个不同场景的实验结果表明该算法能正确地检测出运动车辆,能够满足实时性的要求。     

基于ARCH族模型的沿海煤炭运价指数波动性评价

为较好的刻画我国沿海煤炭运价指数的内在波动规律,采用描述金融时间序列波动性的ARCH族模型进行分析.选取上海航运交易所发布的我国沿海煤炭综合运价指数、秦皇岛-广州、秦皇岛-上海、秦皇岛-宁波3条航线煤炭运价指数为实证研究对象,结果表明:煤炭运价指数收益率序列呈现明显的尖峰厚尾性;GARCH模型能较好的描述煤炭运价指数波动的敏感性及持续性;EGARCH,TGARCH模型能较好的反应煤炭运价指数波动的非对称性.     

阳泉赛鱼大桥荷载试验与分析

交通事业的日益发展对旧桥的承载能力提出了严峻的考验。针对阳泉一双曲拱桥,采用Madis Civil有限元进行分析计算。通过对该桥进行荷载试验,将实测结果与理论计算值相比较,确定了该桥的实际承载能力及运营现状,对现有同类桥梁的管理有一定的借鉴意义。     

Robust adaptive horizontal vibration isolation of towed seismic streamers

The horizontal vibration of towed seismic streamers is a main reason for efficiency reduction of the seismic survey and tail tangling. A vibration suppression scheme of towed seismic streamers is investigated in this paper. The towed seismic streamer is divided into two spans, a controlled span, i.e., the low tension span, and an uncontrolled span, i.e., the high tension span, by a bird. The system model includes a hyperbolic partial differential equation with variable coefficient describing the towed seismic streamers, and an ordinary differential equation describing the dynamic of bird. Robust based-model knowledge and adaptive controllers, based on the Lyapunov method, are designed to isolate the vibration of towed seismic streamers caused by the course deviations of towing vessel, the variations of towing vessel velocity and the variations of towed seismic streamer density. The robust based-model knowledge and adaptive controllers exponentially and asymptotically drive the span-towed seismic streamer displacement to zero, respectively. A finite difference scheme is used to validate the efficiency of the control law. The proposed controller can isolate effectively the disturbance originated from the towed vessel, and can provide the improved damping but not sacrifice the isolation performance. The adaptive scheme can tolerate the lack of knowledge of some uncertain parameters and can directly execute the online adjustment of the parameters. Meanwhile, the proposed control law is robust and can resist the model uncertainty due to parameter incertitude, model error and unknown disturbance and so on. The control law only includes velocity and slope, while it does not need the displacement which is difficult to measure in the practical operations. Thus it is easy to implement.     

Microstructure and hardness of Ni-xSi alloys

The microstructure and hardness of conventionally solidified Ni-xSi (x = 21.4%, 22%, 24%, 26%) alloys were investigated. The solidification microstructures of different Ni-Si alloys were observed by optical microscope (OM) and scanning electron microscope (SEM) and the phase composition was indentified under the help of energy dispersive X-ray (EDX) analysis. The macro- and micro-hardness of the Ni-Si alloys at room temperature were also examined. The experimental results indicated that both the microstructure and hardness closely depended on the Si content. Due to the vast formation of primary ??-Ni₃₁Si₁₂ phase, the hardness of Ni-26.0%Si alloy was significantly improved compared with that of Ni-21.4%Si eutectic alloy. However, the fracture toughness was greatly weakened simultaneously. The (?? ₁-Ni₃Si+??-Ni₃₁Si₁₂) lamellar eutectoid structure formed in the primary ??-Ni₃₁Si₁₂ phase exhibited better ductility than single ??-Ni₃₁Si₁₂ phase at the cost of relatively small hardness reduction.     

Multiple welding seam video transmission and monitoring of welding robot in local area network

A method of transmission and monitoring in local area network (LAN) for the welding seam video information of binocular vision welding robot is proposed. This paper uses MPEG-4 video CODEC functions of DivX, video for Windows (VFW) video capture technology, multi-threaded network communication idea and WinSock Socket in Visual C++ 6.0. In the end, client/server (C/S) communication model based on TCP/IP protocol has been developed. Experimental results show that the method can achieve the multiple welding seam video??s real-time transmission in LAN. Moreover, the Canny operator is used to realize the edge feature extraction of the seam image which is captured by the client, so that the edge of the seam extracted is continuous and clear.     

Effectiveness of different orthoses on joint moments in patients with early knee osteoarthritis: Lateral wedge versus valgus knee bracing

The purpose of the study was to test the biomechanical differences between a lateral wedge and a valgus knee bracing on the knee joint moment during walking in patients with early stage of medial compartment knee osteoarthritis (OA). We conducted a crossover randomized design to compare gait parameters of 32 patients (with early stage medial compartment knee OA) in three different conditions during walking: with a custom-made lateral wedge of 5° (in standard shoes), with a valgus knee bracing (in standard shoes), and with control condition (in standard shoes). Both two-orthose conditions showed decreased loading patterns (knee adduction moment and knee adduction angular impulse) on the knee joint in dynamic condition (statistic probability P < 0.05). The decreased loading on OA knee in wedge condition was associated with a laterally shifted location of centre of pressure and increased ankle valgus degree and moment at the same foot (P < 0.05). It was not found significant differences in loading of the knee between these two-orthose conditions. These results indicated that, under dynamic condition, patients wearing lateral wedge and valgus knee bracing showed changes of moments on knee joints. Lateral wedge was as effective as valgus knee bracing in the treatment of early stage of knee OA.     

电动轿车独立转向轮悬架设计

设计了一种四轮独立转向、独立驱动的电动轿车独立悬架,该悬架采用双横臂、扭杆弹簧结构.将导向机构简化为几何模型,根据该几何模型在ADAMS软件中建立参数化模型,以车轮定位参数及汽车侧倾中心为评价目标,对悬架导向机构进行了优化设计,制造出的样机符合设计要求.提出了悬架扭杆弹簧的设计方法,并验证了其合理性.