全文获取类型
收费全文 | 365篇 |
免费 | 11篇 |
专业分类
公路运输 | 73篇 |
综合类 | 156篇 |
水路运输 | 48篇 |
铁路运输 | 78篇 |
综合运输 | 21篇 |
出版年
2024年 | 2篇 |
2022年 | 1篇 |
2021年 | 8篇 |
2020年 | 8篇 |
2019年 | 5篇 |
2018年 | 6篇 |
2017年 | 5篇 |
2016年 | 9篇 |
2015年 | 16篇 |
2014年 | 23篇 |
2013年 | 18篇 |
2012年 | 33篇 |
2011年 | 24篇 |
2010年 | 35篇 |
2009年 | 22篇 |
2008年 | 23篇 |
2007年 | 33篇 |
2006年 | 34篇 |
2005年 | 22篇 |
2004年 | 13篇 |
2003年 | 8篇 |
2002年 | 2篇 |
2001年 | 6篇 |
2000年 | 7篇 |
1999年 | 2篇 |
1998年 | 1篇 |
1997年 | 1篇 |
1996年 | 1篇 |
1995年 | 1篇 |
1994年 | 1篇 |
1991年 | 2篇 |
1989年 | 2篇 |
1988年 | 1篇 |
1984年 | 1篇 |
排序方式: 共有376条查询结果,搜索用时 140 毫秒
31.
A theoretical foundation for the relationship between generalized origin–destination matrix and flow matrix based on ordinal graph trajectories
下载免费PDF全文
![点击此处可从《先进运输杂志》网站下载免费的PDF全文](/ch/ext_images/free.gif)
This paper shows the relationship between flow, generalized origin–destination (OD), and alternative route flow from a set of ordinal graph trajectories. In contrast to traffic assignment methods that employ OD matrix to produce flow matrix, we use ordinal trajectory on a network graph as input and produce both the generalized OD matrix and the flow matrix, with the alternative and substitute route flow matrices as additional outputs. By using linear algebra‐like operations on matrix sets, the relationship between network utilization (in terms of flow, generalized OD, alternative route flow, and desire line) and network structure (in terms of distance matrix and adjacency matrix) are derived. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
32.
Time-stamped data for transportation and logistics are essential for estimating times on transportation legs and times between successive stages in logistic processes. Often these data are subject to recording errors and omissions. Matches must then be inferred from the time stamps alone because identifying keys are unavailable, suppressed to preserve confidentiality, or ambiguous because of missing observations. We present an integer programming (IP) model developed for matching successive events in such situations and illustrate its application in three problem settings involving (a) airline operations at an airport, (b) taxi service between an airport and a train station, and (c) taxi services from an airport. With data from the third setting (where a matching key was available), we illustrate the robustness of estimates for median and mean times between events under different random rates for “failure to record”, different screening criteria for outliers, and different target times used in the IP objective. The IP model proves to be a tractable and informative tool for data matching and data cleaning, with a wide range of potential applications. 相似文献
33.
国际安全管理规则(ISM)实施后,各航运公司相继实施了体系化管理,体系的建立与运行推动了各航运公司的各项管理工作,对保障船公司船舶安全与防污染起到了根本性的作用。然而,体系运行的有效性问题一直困扰着各家公司。本文分析了体系运行中"假记录"的产生原因、危害及治理方法,仅供同行参考。 相似文献
34.
A novel joint source channel distortion model was proposed, which can essentially estimate the average distortion in progressive image transmission. To improve the precision of the model, the redundancy generated by a forbidden symbol in the arithmetic codes is used to distinguish the quantization distortion and the channel distortion, all the coefficients from the first error one to the end of the sequence are set to be a value within the variance range of the coefficients instead of zero, then the error propagation coming from the entropy coding can be essentially estimated, which is disregarded in the most conventional joint source channel coding (JSCC) systems. The precision of the model in terms of average peak-signal-to-noise has been improved about 0.5 dB compared to classical works. An efficient unequal error protection system based on the model is developed, and can be used in the wireless communication systems. 相似文献
35.
36.
37.
38.
VDR图像压缩方法研究 总被引:3,自引:0,他引:3
简单介绍了船载航行数据记录仪(VDR)的基本功能、系统结构和工作原理,并对其图像压缩方法作了详细介绍.先分别介绍了离散余弦变换(DCT)和嵌入式零树小波编码(EZW)的优缺点,针对VDR图像压缩的具体情况,提出采用DCT和EZW相结合的方法,可发挥它们的优势,克服缺点,达到更好的压缩效果. 相似文献
39.
40.
Given a road network, a fundamental object of interest is the matrix of origin destination (OD) flows. Estimation of this matrix involves at least three sub-problems: (i) determining a suitable set of traffic analysis zones, (ii) the formulation of an optimisation problem to determine the OD matrix, and (iii) a means of evaluating a candidate estimate of the OD matrix. This paper describes a means of addressing each of these concerns. We propose to automatically uncover a suitable set of traffic analysis zones based on observed link flows. We then employ regularisation to encourage the estimation of a sparse OD matrix. We finally propose to evaluate a candidate OD matrix based on its predictive power on held out link flows. Analysis of our approach on a real-world transport network reveals that it discovers automated zones that accurately capture regions of interest in the network, and a corresponding OD matrix that accurately predicts observed link flows. 相似文献