基于GEP的高速公路通行费预测方法研究

高速公路通行费未来收入状况的预测对于高速公路运营管理、建设规划有着重要的指导意义。然而,通行费收入水平的变化受到多方面因素的影响,具有较强的非线性和复杂性,传统预测模型无法准确表达通行费收入的发展规律。本文针对复杂的高速公路通行费预测问题,建立了基于基因表达式编程算法(GEP)的高速公路通行费预测模型。该模型利用GEP算法建立通行费当前收入与历史数据之间复杂的函数关系,准确地刻画通行费收入随时间的发展规律。此外,针对节假日期间通行费减免政策的影响,提出了有效的修正模型。最后,本文采集了浙江沪杭甬高速公路股份有限公司等12家公司通行费收入的历史数据进行仿真实验,对比传统的ARIMA以及神经网络预测模型,结果充分验证了本文算法的有效性和准确性。     

基于Python的网络协议分析工具的研究与应用

随着人们对网络安全重视程度的加深,网络协议朝着复杂化、多样化发展,而传统的协议解析工具存在着扩展性差、功能固定等局限.为了更好地符合实际需要,本文提出一种基于Python的支持自定义协议扩展和密态包解析的网络协议分析工具,主要对网络数据包解析技术进行了研究,采用脚本扩展的方式实现了对数据包的捕获、过滤并进行解析,同时加入了自定义密态包解析功能.实验结果表明,数据包密文部分的解析还原达到了预期效果.     

Bifurcation behaviors of an Euler discretized inertial delayed neuron model

This paper presents an Euler discretized inertial delayed neuron model, and its bifurcation dynamical behaviors are discussed. By using the associated characteristic model, center manifold theorem and the normal form method, it is shown that the model not only undergoes codimension one (flip, Neimark-Sacker) bifurcation, but also undergoes cusp and resonance bifurcation (1:1 and 1:2) of codimension two. Further, it is found that the parity of delay has some effect on bifurcation behaviors. Finally, some numerical simulations are given to support the analytic results and explore complex dynamics, such as periodic orbits near homoclinic orbits, quasiperiodic orbits, and chaotic orbits.     

镉质量浓度和鱼尺寸对罗非鱼积累和转移镉的影响

为研究尺寸和镉(Cd~(2+))质量浓度对罗非鱼积累和转移水环境中Cd~(2+)的影响,用室内培养的方法,选取4种尺寸的罗非鱼,设置不同质量浓度Cd~(2+)的暴露试验,分别测定其半致死率、Cd~(2+)积累量和对Cd~(2+)的转移系数以及罗非鱼的相对增长率.结果表明:不同尺寸的罗非鱼对Cd~(2+)的响应不同,其中,幼龄鱼的LC50浓度最低,体长为31.5±3.4 cm的罗非鱼LC50最高;低质量浓度Cd~(2+)(0.5 mg/kg)处理下,罗非鱼尺寸不同,相同鱼组织对Cd~(2+)的吸收积累量差异显著(P0.05),而高质量浓度Cd~(2+)处理时,不同尺寸罗非鱼的同一组织对Cd~(2+)的积累量无显著性差异;除体长27.4±2.9 cm罗非鱼外,相同尺寸的罗非鱼Cd~(2+)转移系数都是低质量浓度显著大于高质量浓度(P0.05);高质量浓度Cd~(2+)处理对各种尺寸罗非鱼质量增加的抑制率显著高于低质量浓度Cd~(2+)处理的抑制率.此外,不同Cd~(2+)质量浓度对相同尺寸的罗非鱼也产生不同的影响.因此,罗非鱼的尺寸和Cd~(2+)质量浓度都对罗非鱼积累和转移Cd~(2+)产生影响.     

Analytical investigation on thermal-induced warpage behavior of ultrathin chip-on-flex (UTCOF) assembly

The serious warpage issues of ultrathin chip-on-flex (UTCOF) assembly induced by mismatched thermal stresses have greatly affected the mechanical stability and reliability of emerging ultrathin chip packaging technology. Currently, a theoretical prediction as a convenient and straightforward approach is still lacked for describing effectively the thermal-mechanical behavior of UTCOF during the adhesive curing and cooling process. In consideration of the adhesive thickness approximating to ultrathin chip and flexible substrate thickness, we develop a layerwise-model of ultrathin chip-adhesive-flex structure under plain strain condition, where the behavior of thick adhesive bonding can be described precisely through increasing the subdivided mathematical plies. Further, the analytical results show that the concave and convex forms of ultrathin chip warpage yield at the end of the curing and cooling process respectively. Meanwhile, the effects of its structure dimensions and material properties are also revealed for discussing a way to relieve the extent of ultrathin chip warpage. Additionally, in order to verify the validity of the theoretical prediction, we also introduce the corresponding numerical technique and experimental method. These results suggest that a kind of rigid and ultrathin flexible substrate such as metal foil should be adopted for small warpage of ultrathin assembly.     

Kinetic theory for aquatic animal distribution simulation

Identifying the underlying mechanisms that influence the spatial patterns in populations improves the forecasts of the alternative management strategies on the spatial dynamics of the populations, which are critical for assessing and managing the fisheries and improving the water resource management. This paper described a new approach of the numerical model for the prediction of the aquatic animal distribution in the flows. The model was developed based on the kinetic theory of gases, the mechanism of the aquatic animal movement and the flow hydrodynamic patterns. The model was validated using the available experimental data and an acceptable agreement was obtained. A comprehensive parameter study was then conducted to help understand the impact and the sensitivity of each parameter to the aquatic animal distribution. The promising results of the model reveal the prospect of applying this model to the reliable prediction of the aquatic animal distribution within a relatively large water area.     

Boost变换器负调电压建模分析

摘要 以电容电压作为输出反馈的Boost变换器是一个非最小相位系统,非最小相位反应引起的负调严重的影响系统的暂态性能及稳态性能。研究引起负调与变换器参数之间的关系对Boost变换器优化设计是一个关键问题。本文根据Boost变换器小信号数学模型推导给出非最小相位系统的负调电压表达式,指出衡量负调电压的两个指标：负调电压大小和负调电压峰值时间。根据负调电压表达式分析了输入电压、储能电感、占空比、占空比变化量、负载、滤波电容等参数对负调电压的影响。研究结果表明：输入电压和占空比变化量仅影响负调电压大小;储能电感、占空比、负载、滤波电容不仅影响负调的大小,同时影响负调的峰值时间。研究所得结论为Boost变换器的参数优化设计以及减小负调电压提高系统暂态性能及稳态性能提供了理论依据。仿真和实验结果验证了理论分析的正确性。     

皮尔格轧机冷轧不锈钢管回弹预测模型的建立与验证

以皮尔格LG60轧机轧制304不锈钢管为例,研究皮尔格轧机冷轧不锈钢管回弹预测模型。首先通过单向拉伸试验及数据处理的方法得到材料的分段非线性本构方程;其次根据钢管轧制的塑性变形规律结合增量理论,得到变形过程中各应变分量的计算方法,并把钢管变形过程中的受力状态由三向应力状态转化为单向应力状态,利用材料的卸载定律建立冷轧钢管的回弹预测模型;最后通过大型有限元模拟软件DEFORM-3D进行完整轧制过程的3维有限元模拟仿真,并利用皮尔格轧机进行实际轧制试验验证来检验回弹预测模型的可靠性与正确性。结果表明,本模型精度较高,对皮尔格轧机孔型设计及实际生产中成品管尺寸精度控制有重要指导意义。     

基于Pro/E的机柜参数化设计

基于Pro/E软件的三维建模及其参数化功能,结合厂家型材,采用参数化设计方法,建立了某种机柜的参数化模型。机柜参数化设计方法和传统设计方法在实际工作中的应用情况对比结果表明,机柜参数化设计方法可大幅缩短机柜设计的时间,提高设计效率。     

双频激电法在某地热勘查中的应用

主要介绍采用双频激电测深对江西某地区地热进行勘查.以视电阻率为主,对不同测深点所测得的数据进行处理、一维反演,结合地质资料,圈定低阻含水层,进一步作出规划,以便降低钻探的成本.