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91.
The need for acquiring the current-year traffic data is a problem for transport planners since such data may not be available
for on-going transport studies. A method is proposed in this paper to predict hourly traffic flows up to and into the near
future, using historical data collected from the Hong Kong Annual Traffic Census (ATC). Two parametric and two non-parametric
models have been employed and evaluated in this study. The results show that the non-parametric models (Non-Parametric Regression
(NPR) and Gaussian Maximum Likelihood (GML)) were more promising for predicting hourly traffic flows at the selected ATC station.
Further analysis encompassing 87 ATC stations revealed that the NPR is likely to react to unexpected changes more effectively
than the GML method, while the GML model performs better under steady traffic flows. Taking into consideration the dynamic
nature of the common traffic patterns in Hong Kong and the advantages/disadvantages of the various models, the NPR model is
recommended for predicting the hourly traffic flows in that region. 相似文献
92.
In this paper, urban network design is analysed through a heuristic multi-criteria technique based on genetic algorithms. Both network layout and link capacity (link layout and traffic lights) are optimised. Different optimisation criteria are included for users, non-users and public system managers. Demand is considered elastic with respect to mode choice; both morning and afternoon peak periods are taken into account. In addition, choice of parking location is simulated. The procedure is applied to a test and to a real transportation system. 相似文献
93.
超声波测距传感器及其在自动调平系统中的应用 总被引:3,自引:0,他引:3
赵国普 《筑路机械与施工机械化》2002,19(6):20-22
详细介绍了超声波测距传感器的测距原理及其测试精度的影响因素 ,分析了它在自动调平系统应用中的结构形式和提高控制精度的注意事项 相似文献
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98.
Shoichi?HaraEmail author Kenji?Yamakawa Kunihiro?Hoshino Kazuhiro?Yukawa 《Journal of Marine Science and Technology》2004,8(3):138-146
A huge floating offshore platform (359m long, 60m wide, and 3m deep) was towed into the Pacific Ocean for a validation experiment for a floating airport. Full-scale measurements of towline tension and the bending strain on the upper-deck were made during towing. The measured bending moment agreed well with numerical calculation without taking the draught and towing speed into consideration. 相似文献
99.
Gang?Liu Yukio?FujimotoEmail author Yoshikazu?Tanaka Eunsang?Im 《Journal of Marine Science and Technology》2004,9(2):63-69
A stress intensity factor (SIF) measurement method for cracks using a piezoelectric element and an electrostatic voltmeter is presented. In this method, an isotropic piezoelectric element is first attached near the tip of the crack. Then surface electrodes are attached to three different positions on the piezoelectric element. The electric potentials of the surface electrodes, which are proportional to the sum of the stress (
x
+
y
) on the structural member, are measured by an electrostatic voltmeter during load cycling. The mode I and mode II SIFs of the crack are estimated using the relationship between the SIF and (
x
+
y
). The applicability of the proposed method is examined through experiments and numerical analysis. 相似文献
100.
为了解砂卵石地层隧道围岩和支护结构的应力应变特性,以青海循隆高速公伯峡隧道为依托,借助PFC3D离散元软件对公伯峡隧道穿越砂卵石地层进行三维模拟,重点研究以密排短管棚预支护为根本前提,以三台阶预留核心土为施工方法的砂卵石地层围岩和支护结构的应力应变特性,并与现场实测进行对比分析。研究结果表明: 隧道台阶开挖时,围岩应力集中范围逐渐从拱顶过渡到拱腰,直到拱脚,对应的塑性区范围不断扩大,且密排短管棚对塑性区的发展有一定的“遮拦效应”; 围岩横纵向变形规律一致,主要是向隧道临空面产生收敛变形,且密排短管棚形成的梁拱效应限制了掌子面前方位移发展; 2种方法得到的初期支护变形规律一致,均呈阶段性变化,拱顶下沉累计值大于周边收敛累计值,且两者的最终变形量均满足规范限值要求。 相似文献