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排序方式: 共有617条查询结果,搜索用时 15 毫秒
1.
Combinatorial auction is a useful trade manner for transportation service procurements in e-marketplaces. To enhance the competition of combinatorial auction, a novel auction mechanism of two-round bidding with bundling optimization is proposed. As the recommended the auction mechanism, the shipper/auctioneer integrates the objects into several bundles based on the bidding results of first round auction. Then, carriers/bidders bid for the object bundles in second round. The bundling optimization is described as a multi-objective model with two criteria on price complementation and combination consistency. A Quantum Evolutionary Algorithm (QEA) with β-based rotation gate and the encoding scheme based on non-zero elements in complementary coefficient matrix is developed for the model solution. Comparing with a Contrast Genetic Algorithm, QEA can achieve better computational performances for small and middle size problems. 相似文献
2.
This paper evaluates the behavior and performance of laminated circular elastomeric bearings and compares them to those of square and rectangular bearings. The study included an experimental evaluation and a nationwide survey of state Department of Transportations on the use and performance of circular bearings and bearings in general in their states. The experimental investigation studied the bearings' behavior in compression, compression and rotation, and compression and shear. Results from this limited study showed that the three bearings have similar stress-strain behavior in compression and they are in agreement with the AASHTO LRFD guide stress–strain curves. In compression and rotation, the AASHTO LRFD substructure moments are slightly less than the measured values for circular bearings and rectangular bearings rotated about their strong axis for a compressive stress of 10.3?MPa (1.5?ksi) and slightly higher than those of rectangular bearings rotated about their weak axis. In compression and shear, the shear stiffness of circular and square bearings is in agreement with theoretical values within the range of design displacements. Results from the survey showed that many states are using circular bearings and more states would consider using them, however no maintenance or monitoring data were available on their short-term and long-term performance. 相似文献
3.
莫灿林 《浙江理工大学学报》1992,(1)
根据空间RSCR四杆机构出现特殊位置的几何特征,运用旋转变换把空间问题转换为平面问题,对实现两特殊位置运动的空间RSCR曲柄摇杆机构的图解综合法进行了探讨。 相似文献
4.
介绍了一种实用新型干红葡萄酒发酵罐。它利用设置在罐顶的旋转喷淋装置对浮于液面上的葡萄皮进行间歇喷淋。解决了葡萄皮由于长期与空气接触而变质发霉的问题。与上次介绍的压板式干红葡萄酒发酵罐的区别在于:它具有制造难度小、生产成本低、维护容易等优点。适用于中小型葡萄酒厂的推广与应用。 相似文献
5.
Rotational Restraint of Pile Caps during Lateral Loading 总被引:1,自引:0,他引:1
A pure fixed-head (zero-rotation) condition at the top of a group of laterally loaded piles is seldom achievable in the field, even when piles are installed in a group that is “rigidly” constrained by a stiff concrete pile cap. Assuming complete fixity during design (zero rotation at the pile head) can result in underestimated values of pile-head deflection, and incorrect estimates of the magnitude and the location of maximum bending moments. A simple and practical approach is presented for estimating the moment restraint that is provided by the pile cap at the top of a pile group. The moment restraint, represented by the rotational restraint coefficient (KMθ), serves as a boundary condition for analyzing groups of laterally loaded piles. Full-scale field tests performed on two pile groups with concrete pile caps show that the proposed method for estimating rotational restraint provides results that are in good agreement with measured field performance. 相似文献
6.
7.
《Computer Aided Geometric Design》2014,31(3-4):199-209
This paper addresses the problem of determining the symmetries of a plane or space curve defined by a rational parametrization. We provide effective methods to compute the involution and rotation symmetries for the planar case. As for space curves, our method finds the involutions in all cases, and all the rotation symmetries in the particular case of Pythagorean-hodograph curves. Our algorithms solve these problems without converting to implicit form. Instead, we make use of a relationship between two proper parametrizations of the same curve, which leads to algorithms that involve only univariate polynomials. These algorithms have been implemented and tested in the Sage system. 相似文献
8.
9.
Random Forests receive much attention from researchers because of their excellent performance. As Breiman suggested, the performance of Random Forests depends on the strength of the weak learners in the forests and the diversity among them. However, in the literature, many researchers only considered pre-processing of the data or post-processing of the Random Forests models. In this paper, we propose a new method to increase the diversity of each tree in the forests and thereby improve the overall accuracy. During the training process of each individual tree in the forest, different rotation spaces are concatenated into a higher space at the root node. Then the best split is exhaustively searched within this higher space. The location where the best split lies decides which rotation method to be used for all subsequent nodes. The performance of the proposed method here is evaluated on 42 benchmark data sets from various research fields and compared with the standard Random Forests. The results show that the proposed method improves the performance of the Random Forests in most cases. 相似文献
10.
针对采用单一方法提取图像特征时检索率不高的问题,结合非下采样剪切波变换(NSST)统计特征和旋转不变的局部相位量化(RI-LPQ)原理,提出一种纹理图像检索方法。非下采样剪切波不仅具有方向选择性及平移不变性,而且可以对图像进行有效的稀疏表示,与传统小波相比,可有效捕捉图像的边缘轮廓等纹理信息,与非下采样轮廓波相比,具有更高的计算效率。利用广义高斯分布函数对图像NSST高频子带系数的统计特征进行分析,RI-LPQ描述算子直接提取图像特征,采用具有权重系数的相似性测度公式对Brodatz图像库进行纹理图像检索。实验结果表明,与传统小波和轮廓波的方法相比,NSST统计特征方法的平均检索率分别提高4.77%和1.44%,纹理图像检索方法的平均检索率分别提高7.36%和1.98%。 相似文献