Parking Capacity and Pricing in Park'n Ride Trips: A Continuous Equilibrium Network Design Problem

In this paper we consider the problem of designing parking facilities for park'n ride trips. We present a new continuous equilibrium network design problem to decide the capacity and fare of these parking lots at a tactical level. We assume that the parking facilities have already been located and other topological decisions have already been taken.The modeling approach proposed is mathematical programming with equilibrium constraints. In the outer optimization problem, a central Authority evaluates the performance of the transport network for each network design decision. In the inner problem a multimodal traffic assignment with combined modes, formulated as a variational inequality problem, generates the share demand for modes of transportation, and for parking facilities as a function of the design variables of the parking lots. The objective is to make optimal parking investment and pricing decisions in order to minimize the total travel cost in a subnetwork of the multimodal transportation system.We present a new development in model formulation based on the use of generalized parking link cost as a design variable.The bilevel model is solved by a simulated annealing algorithm applied to the continuous and non-negative design decision variables. Numerical tests are reported in order to illustrate the use of the model, and the ability of the approach to solve applications of moderate size.     

Low-energy ion-assisted control of interfacial structures in metallic multilayers

A molecular dynamics method has been used to simulate the argon ion-assisted deposition of Cu/Co/Cu multilayers and to explore ion beam assistance strategies that can be used during or after the growth of each layer to control interfacial structures. A low-argon ion energy of 5–10 eV was found to minimize a combination of interfacial roughness and interlayer mixing (alloying) during the ion-assisted deposition of multilayers. However, complete flattening with simultaneous ion assistance could not be achieved without some mixing between the layers when a constant ion energy approach was used. It was found that multilayers with lower interfacial roughness and intermixing could be grown either by modulating the ion energy during the growth of each metal layer or by utilizing ion assistance only after the completion of each layers deposition. In these latter approaches, relatively high-energy ions could be used since the interface is buried and less susceptible to intermixing. The interlayer mixing dependence upon the thickness of the over layer has been determined as a function of ion energy.     

基于V-视差法的道路区域检测算法研究

针对当前基于双目视觉的道路环境分析实时性差、检测不准确等问题,提出了一种改进V视差法的道路区域检测算法。该算法首先对原始图片进行车道线检测确定道路消失点,从而确定图像的感兴趣区域。然后,使用极大最小值约束获取V视差图中的斜线,从而提取道路区域。实验结果表明,由于该方法在确定感兴趣区域后计算原始视差图,因此,速度提高了29.71%,且相对于传统V视差法,算法更好地实现了路面分割;同时,障碍物检测的精确率和召回率两个指标分别提高了2.165%和4.837%。基于该算法具有良好的准确性和实时性,能有效识别道路中的障碍物,因此,可以为车辆提供可行驶区域以及为驾驶员提供辅助作用。     

考虑车辆随机停放的停车楼减震设计与可靠度分析

在停车楼的设计中通常将车辆荷载以活荷载的方式均匀分布到结构上,实际上受车辆随机停放的影响,停车楼结构整体质量中心偏移,一旦结构遭遇罕遇地震时,车辆的随机停放可能造成停车楼结构发生扭转破坏.本文在传统减震设计方法的基础上考虑车辆活荷载的随机性,并从可靠度的角度验算减震结构在大震作用下的倒塌概率.结果表明,相同的减震设计布...     

基于机器视觉技术的智能停车管理系统的研究

基于机器视觉技术的智能停车管理系统的研究是为了解决城市停车场激增、停车管理效率低下而涉及的一种智能交通系统的应用发展领域。现提出了一种由车辆检测模块、车牌识别模块、车位查询模块及车辆跟踪模块所构成的智能停车场管理系统,并对其中的车牌定位检测及识别以及车位查询模块进行了相应测试,结果较为合理。     

基于移动通信的城市停车诱导信息系统设计

随着汽车保有量不断增加,停车难已成为城市交通普遍问题。从分析城市停车诱导系统功能和提高停车设施利用率的角度出发,结合实际城市交通情况,采用PGIS技术,提出一个整体性、实时动态的停车诱导信息系统。该系统设计通过仿真验证有效．因此将为城市交通管理控制、驾驶员出行提供更准确和有效的诱导决策辅助信息。     

SRAM dynamic stability estimation using MPFP and its applications

In this paper, an accurate approach for estimating the dynamic stability of static random access memory (SRAM) is proposed. The conventional methods of SRAM stability estimation suffer from two major drawbacks: (1) using static failure criteria, such as SNM, which does not capture the transient and dynamic behavior of SRAM operation, and (2) using quasi-Monte-Carlo simulation, which approximates the failure distribution, resulting in large errors at the tails where the desired failure probabilities exist. These drawbacks are eliminated by employing accurate simulation-based dynamic failure criteria along with a new distribution-independent, Most-probable-failure-point search technique for accurate probability calculation. Compared to previously published techniques, the proposed dynamic stability technique offers orders of magnitude improvement in accuracy. Furthermore, the proposed dynamic stability technique enables the correct evaluation of stability in real operation conditions and for different dynamic circuit techniques, such as dynamic write back, where the conventional methods are not applicable.     

Oxygen assisted laser cutting mechanism—a laminar boundary layer approach including the combustion process

The present study examines the combined effects of chemical reactions taking place between a gas jet and molten metal, the cooling effect of the jet and the evaporation of metal, during a CO₂ laser cutting process. A laminar boundary layer approach was used to develop a theoretical model for the oxygen gas jet laser cutting mechanism. An experiment was carried out to monitor the keyhole formation using a video recorder and detect the light emitted from the entrance and exist surfaces of the workpiece using a fibre-optic probe during the cutting process. The experimental study was extended to employ two different workpiece materials (stainless steel and mild steel) at two thicknesses, and varying oxygen assisting gas pressures. It is found that the theoretical model developed in the present study is valid for a cutting speed of about 30 mm s⁻¹ and all jet velocities up to sonic, since the effect of shock is excluded in the model.     

Trees, parking functions, syzygies, and deformations of monomial ideals

For a graph , we construct two algebras whose dimensions are both equal to the number of spanning trees of . One of these algebras is the quotient of the polynomial ring modulo certain monomial ideal, while the other is the quotient of the polynomial ring modulo certain powers of linear forms. We describe the set of monomials that forms a linear basis in each of these two algebras. The basis elements correspond to -parking functions that naturally came up in the abelian sandpile model. These ideals are instances of the general class of monotone monomial ideals and their deformations. We show that the Hilbert series of a monotone monomial ideal is always bounded by the Hilbert series of its deformation. Then we define an even more general class of monomial ideals associated with posets and construct free resolutions for these ideals. In some cases these resolutions coincide with Scarf resolutions. We prove several formulas for Hilbert series of monotone monomial ideals and investigate when they are equal to Hilbert series of deformations. In the appendix we discuss the abelian sandpile model.

     

Expected Sums of General Parking Functions

A (u₁, u₂, . . . )-parking function of length n is a sequence (x₁, x₂, . . . , x_n) whose order statistics (the sequence (x₍₁₎, x₍₂₎, . . . , x_(n)) obtained by rearranging the original sequence in non-decreasing order) satisfy x_(i) u_(i). The Gonarov polynomials g _n (x; a₀, a ₁, . . . , a _n-1) are polynomials biorthogonal to the linear functionals (a _i) Dⁱ, where (a) is evaluation at a and D is differentiation. In this paper, we give explicit formulas for the first and second moments of sums of u-parking functions using Gonarov polynomials by solving a linear recursion based on a decomposition of the set of sequences of positive integers. We also give a combinatorial proof of one of the formulas for the expected sum. We specialize these formulas to the classical case when u _i=a+ (i-1)b and obtain, by transformations with Abel identities, different but equivalent formulas for expected sums. These formulas are used to verify the classical case of the conjecture that the expected sums are increasing functions of the gaps u_i+1 - u_i. Finally, we give analogues of our results for real-valued parking functions.AMS Subject Classification: 05A15, 05A19, 05A20, 05E35.