时变交通拥挤和需求随机的移动设施运营优化

为了优化移动设施(Mobile Facility,MF)的运营,在充分考虑时变交通状况和用户需求随机性的基础上,构建了一个两阶段随机规划模型,以期为决策者提供有力的工具。在第一阶段,模型针对MF的数量、时刻表和路径进行决策;第二阶段则聚焦于用户需求的分配和未满足服务量的确定。在求解此模型的过程中,本研究结合了时间依赖最短路径算法与L-shaped算法。在解决MF的移动路径和用户到达服务点的时间依赖最短路径问题时,将时变路段行驶速度离散化为分段函数,使得路段行驶时间成为连续分段线性函数,并且满足网络先进先出的原则,从而可以修改现有最短路径算法高效求解时间依赖最短路径。在L-shaped算法中,视一阶段模型为主问题,二阶段模型为子问题。首先通过求解主问题获得一阶段的决策变量,然后利用这些变量求解子问题,为主问题生成最优割。通过主、子问题的迭代交互,实现了对模型全局最优解的收敛,同时,通过加入有效不等式,使得算法能够快速收敛。在上海市嘉定区COVID-19核酸检测服务的MF实例中,对所提出的模型和算法进行了实证研究。结果表明:多割L-shaped算法结合有效不等式显著提升求解效率;同时,随着用户需求分布情况数量的增加,完美信息期望值和随机解价值均显著增加,这强调了在决策过程中获取准确信息和考虑时变交通状况与需求随机性的重要性。

The wave and vibratory power transmission in a finite L-shaped Mindlin plate with two simply supported opposite edges

In this paper,wave and vibratory power transmission in a finite L-shaped Mindlin plate with two simply supported opposite edges are investigated using the wave approach.The dynamic responses,active and reactive power flow in the finite plate are calculated by the Mindlin plate theory （MPT） and classic plate theory （CPT）.To satisfy the boundary conditions and continuous conditions at the coupled junction of the finite L-shaped plate,the near-field and far-field waves are entirely contained in the wave approach.The in-plane longitudinal and shear waves are also considered.The results indicate that the vibratory power flow based on the MPT is different from that based on the CPT not only at high frequencies but also at low and medium frequencies.The influence of the plate thickness on the vibrational power flow is investigated.From the results it is seen that the shear and rotary inertia correction of the MPT can influence the active and reactive power at the junction of the L-shaped plate not only at high frequencies but also at low and medium frequencies.Furthermore,the effects of structural damping on the active and reactive power flow at the junction are also analyzed.

Joint 2D DOA and Doppler frequency estimation for L-shaped array using compressive sensing

A joint two-dimensional(2D)direction-of-arrival(DOA)and radial Doppler frequency estimation method for the L-shaped array is proposed in this paper based on the compressive sensing(CS)framework.Revised from the conventional CS-based methods where the joint spatial-temporal parameters are characterized in one large scale matrix,three smaller scale matrices with independent azimuth,elevation and Doppler frequency are introduced adopting a separable observation model.Afterwards,the estimation is achieved by L1-norm minimization and the Bayesian CS algorithm.In addition,under the L-shaped array topology,the azimuth and elevation are separated yet coupled to the same radial Doppler frequency.Hence,the pair matching problem is solved with the aid of the radial Doppler frequency.Finally,numerical simulations corroborate the feasibility and validity of the proposed algorithm.

Laboratory test on the combined cooling effect of L-shaped thermosyphons and thermal insulation on high-grade roadway construction in permafrost regions

With the completion of the Qinghai-Tibetan Railway,economic development of related areas has been greatly accelerated.This,in return,calls for building or upgrading more roadways,especially high-grade roadways.In cold regions,the thawing of permafrost can induce settlement damage of and even failure to railway (or roadway) embankments.Thermosyphons (self-powered refrigera-tion devices that are used to help keep the permafrost cool) have proved effective in mitigating thaw settlement by maintaining the thermal stability of the embankments.However,for high-grade roadway embankments of great width,stabilizing or cooling ef-fects of traditional geotechnological measures may be limited.To enhance the cooling effect of thermosyphons,an L-shaped thermosyphon was designed.A laboratory test was carried out to study the combined cooling effect of the L-shaped thermosyphon and thermal insulation applying to roadbed construction.The angle between the evaporator and condenser sections of the L-shaped thermosyphon is 134 degrees,and the L-shaped thermosyphon was inserted into the soil at an angle of 5 degrees with the road surface.The tested results show that the L-shaped thermosyphon is effective in removing heat from a roadway in winter.When the ambient air temperature is lower than the soil temperature,the thermosyphon is active and extracts the heat in the soil around it.When the ambient air temperature is higher than the soil temperature,the thermosyphon is inactive,and no heat is in-jected into the soil through the L-shaped thermosyphon.Compared to embankments with straight thermosyphons,the inner parts of the embankments with L-shaped thermosyphons were significantly cooled.It is hoped that the present study would be useful to the application of L-shaped thermosyphons in the construction of high-grade roadways in cold regions.

Test on mechanical behavior of SRC L-shaped columns under combined torsion and bending moment

Investigations of the seismic behavior of steel reinforced concrete L-shaped columns under constant axial compression and cycled bending-shear-torsion load were performed.Six specimens,which considered two parameters,i.e.,the moment ratio of torsion to bending(γ)and the aspect ratio(column length-to-depth ratio,φ),were prepared for the experiment.In this study,the failure process,torsion-displacement hysteresis curves,and flexure-displacement hysteresis curves were obtained.The failure characteristics,mechanical behavior of specimens such as the failure patterns,hysteresis curves,rigidity degradation,ductility and energy dissipation,are analyzed.The experimental research indicated that the major failures of the specimens were bending failure,bending-shear failure and bending-torsion failure as the moment ratio of torsion to bending(γ)increased.The torsion-displacement hysteresis curves were pinched in the middle,formed a slip platform,and the phenomenon of“load drop”occurred after the peak load.The bending-displacement hysteresis curves were plump,which showed that bending capacity of the specimen was better than its torsion capacity.Additionally,the energy dissipation of the specimen was dominated by torsion in the early stage and ultimately governed by the bending moment in the later phase.Test results also indicated that the displacement ductility coefficient and interstory rotation angle of the failure point were less than 3.0 and 1/50,respectively,which means the test specimen performance does not meet the requirement of the Chinese Code for Seismic Design of Buildings(GB 50011-2014)in this respect.

Research for the orientation detection system using L-shape reticle

The basic scheme of the orientation detection system using L-shape reticle is introduced. The dimension of the patterns on the reticle of the system in practical applications is designed and an analysis of the principle of abstracting the orientation information of the target and the effects and formation method of self-adapting tracking gate is presented. The research result shows that the orientation detection system using L-shape reticle has a good effect on space-filtering, the signals that the orientation detection system sends out are easy to be processed by computer, its self-adapting tracking gate has a strong anti-interference ability, and the whole system＇s searching and tracking performances are quite high.

Effects of Lay-up Types of Out-of-autoclave Prepregs on Preparation Quality of L-shape Composite Laminates

Effects of layer quantities and stacking sequences on L-shape composite manufacturing qualities in using OOA(out-of-autoclave)prepregs were studied.The mechanisms of air evacuated in 5 kinds of lay-ups were revealed by image analysis of cut surfaces and thickness measurements.Results show that air in OOA prepregs is evacuated in two ways.Most of the air is forced out of layers directly by vacuum before air accesses in prepregs closed.Very little entrapped air moves perpendicularly to outer layers under hydrostatic resin pressure.When a laminate contains less than 16 layers,voids can hardly be found in layers.When a laminate contains more than 16 layers,voids cannot be expelled completely during the window of vertical movement.As for stacking sequences,the synergetic effect of slip function and nest function determines the thickness and voids content of laminates.Results show that the average of single layer thickness of unidirectional layers is the lowest,and the average of single layer thickness of quasi-isotropic layers is the highest.The voids content of quasi isotropic is the highest,which is consistent with the theoretical analysis.

Multicut L-Shaped Algorithm for Stochastic Convex Programming with Fuzzy Probability Distribution

Two-stage problem of stochastic convex programming with fuzzy probability distribution is studied in this paper. Multicut L-shaped algorithm is proposed to solve the problem based on the fuzzy cutting and the minimax rule. Theorem of the convergence for the algorithm is proved. Finally, a numerical example about two-stage convex recourse problem shows the essential character and the efficiency.

Physics-informed neural networks with residual/gradient-based adaptive sampling methods for solving partial differential equations with sharp solutions

We consider solving the forward and inverse partial differential equations(PDEs)which have sharp solutions with physics-informed neural networks(PINNs)in this work.In particular,to better capture the sharpness of the solution,we propose the adaptive sampling methods(ASMs)based on the residual and the gradient of the solution.We first present a residual only-based ASM denoted by ASMⅠ.In this approach,we first train the neural network using a small number of residual points and divide the computational domain into a certain number of sub-domains,then we add new residual points in the sub-domain which has the largest mean absolute value of the residual,and those points which have the largest absolute values of the residual in this sub-domain as new residual points.We further develop a second type of ASM(denoted by ASMⅡ)based on both the residual and the gradient of the solution due to the fact that only the residual may not be able to efficiently capture the sharpness of the solution.The procedure of ASMⅡis almost the same as that of ASMⅠ,and we add new residual points which have not only large residuals but also large gradients.To demonstrate the effectiveness of the present methods,we use both ASMⅠand ASMⅡto solve a number of PDEs,including the Burger equation,the compressible Euler equation,the Poisson equation over an Lshape domain as well as the high-dimensional Poisson equation.It has been shown from the numerical results that the sharp solutions can be well approximated by using either ASMⅠor ASMⅡ,and both methods deliver much more accurate solutions than the original PINNs with the same number of residual points.Moreover,the ASMⅡalgorithm has better performance in terms of accuracy,efficiency,and stability compared with the ASMⅠalgorithm.This means that the gradient of the solution improves the stability and efficiency of the adaptive sampling procedure as well as the accuracy of the solution.Furthermore,we also employ the similar adaptive sampling technique for the data points of boundary conditions(BCs)if the sharpness of the solution is near the boundary.The result of the L-shape Poisson problem indicates that the present method can significantly improve the efficiency,stability,and accuracy.

考虑动态频率约束的一次调频和二次调频联合优化模型

可再生能源大规模并网导致电力系统频率稳定问题凸显,调频需求与供给矛盾日益突出,现有的单一调频辅助服务模式逐渐难以满足系统运行要求。文章在梳理国外调频辅助服务市场机制的基础上,提出了一种考虑动态频率约束的一次调频和二次调频联合优化出清的安全约束机组组合模型,以提高系统频率响应能力;并采用L-shape方法将非线性问题转化为两阶段的混合整数线性规划问题进行协同优化求解。在此基础上,探讨机会成本的补偿费用。最后,基于算例验证了所提模型的有效性,并讨论了考虑一次调频后对市场出清费用和机会费用的影响,可为我国调频辅助服务市场机制建设提供参考。

基于Dynaform的L形件弯曲工艺参数优化分析

回弹与起皱是弯曲件成形过程中最大的质量问题.以典型的L形件弯曲成形工艺参数为研究对象,设计正交试验,并利用Dynaform有限元分析软件对弯曲件成形过程进行数值模拟,分析压边力变化时长占比、最小压边力、最大压边力以及凹模圆角半径对弯曲件成形质量的影响规律.以成形裕度为约束条件,回弹角、起皱波纹度为参考指标,基于数值模拟与极差计算结果,得到弯曲成形最优工艺参数.模拟验证结果为回弹角控制在0.3°以内,波纹度控制在0.773%左右,最大限度地减少了工件形位尺寸误差.

基于Dynaform的L形件弯曲回弹有限元分析

以L形件为研究对象,根据板料成形特点及回弹规律,利用Dynaform软件对L形件冲压成形进行了回弹仿真试验。依据回弹仿真试验结果,用正交试验法对冲压参数凸凹模圆角半径、板材厚度、压边力和摩擦系数与L形件冲压回弹之间的关系进行了分析。结果显示,凸凹模圆角半径、板材厚度、摩擦系数对L形件的冲压回弹有显著影响。当弯曲工艺参数处于合理范围内时,L形冲压件回弹量随凸凹模圆角半径增大而增大;随板料厚度的增大而越小;随摩擦系数和压边力的增大,回弹角先增后减。

“L”形皮瓣的临床应用

目的介绍L形皮瓣在体表皮肤缺损修复中的应用方法与经验。方法自2003年4月～2006年8月,应用L形皮瓣修复面部、躯干及肢体皮肤缺损20例。其中面颈部12例,躯干4例,四肢4例,缺损面积最小者0.5cm×0.8cm,最大者7cm×10cm。结果术后除1例皮瓣尖端表皮坏死外,其余均完全成活。结论L形皮瓣具有操作简单、血运可靠及转移后张力分布均匀等优点。尤其适用于面颈部面积不大但又不能直接缝合的创面修复。

Estimating DOA and polarization with spatially spread loop and dipole pair array

The nonuniform L-shaped spatially spread loop and dipole（SSLD） array whose inter-element spacing is greater than half a wavelength is studied. A joint parameter estimation algorithm of direction of arrival（DOA）, frequency and polarization is presented for plane-wave signals. The direct sampling and the corresponding delayed sampling data are used to construct the data correlation matrix. On the basis of the subspace theory and the least square method, the frequency and the steering vector of the whole array are obtained. According to the relationship of the array manifold vector between electric dipoles and magnetic loops,the polarization parameters are given. The unambiguous phase estimates are acquired by applying virtual baseline array transformation to the spatial steering vectors, and they are used as coarse references to disambiguate the cyclic phase ambiguities in phase differences between two adjacent array elements on the array,then the high accuracy DOA estimates are obtained. Closed-form solutions for each parameter are obtained. This method has advantages of lower calculation complexity and no parameter matching. The experiment results verify the effectiveness and feasibility of the presented algorithm.

On Tilings of Quadrants and Rectangles and Rectangular Pattern

The problem of tiling rectangles by polyominoes generated large interest. A related one is the problem of tiling parallelograms by twisted polyominoes. Both problems are related with tilings of (skewed) quadrants by polyominoes. Indeed, if all tilings of a (skewed) quadrant by a tile set can be reduced to a tiling by congruent rectangles (parallelograms), this provides information about tilings of rectangles (parallelograms). We consider a class of tile sets in a square lattice appearing from arbitrary dissections of rectangles in two L-shaped polyominoes and from symmetries of these tiles about the first bisector. Only translations of the tiles are allowed in a tiling. If the sides of the dissected rectangle are coprime, we show the existence of tilings of all (skewed) quadrants that do not follow the rectangular (parallelogram) pattern. If one of the sides of the dissected rectangle is 2 and the other is odd, we also show tilings of rectangles by the tile set that do not follow the rectangular pattern. If one of the sides of the dissected rectangle is 2 and the other side is even, we show a new infinite family of tile sets that follows the rectangular pattern when tiling one of the quadrants. For this type of dis-section, we also show a new infinite family that does not follow the rectangular pattern when tiling rectangles. Finally, we investigate more general dissections of rectangles, with. Here we show infinite families of tile sets that follow the rectangular pattern for a quadrant and infinite families that do not follow the rectangular pattern for any quadrant. We also show, for infinite families of tile sets of this type, tilings of rectangles that do not follow the rectangular pattern.

Signed Tilings by Ribbon L n-Ominoes, n Even, via Gröbner Bases

Let Tn be the set of ribbon L-shaped n-ominoes for some n≥4 even, and let T+n be Tn with an extra 2 x 2 square. We investigate signed tilings of rectangles by Tn and T+n . We show that a rectangle has a signed tiling by Tn if and only if both sides of the rectangle are even and one of them is divisible by n, or if one of the sides is odd and the other side is divisible by . We also show that a rectangle has a signed tiling by T+n, n≥6 even, if and only if both sides of the rectangle are even, or if one of the sides is odd and the other side is divisible by . Our proofs are based on the exhibition of explicit GrÖbner bases for the ideals generated by polynomials associated to the tiling sets. In particular, we show that some of the regular tiling results in Nitica, V. (2015) Every tiling of the first quadrant by ribbon L n-ominoes follows the rectangular pattern. Open Journal of Discrete Mathematics, 5, 11-25, cannot be obtained from coloring invariants.

Signed Tilings by Ribbon L n-Ominoes, n Odd, via Gröbner Bases

We show that a rectangle can be signed tiled by ribbon L n-ominoes, n odd, if and only if it has a side divisible by n. A consequence of our technique, based on the exhibition of an explicit Gröbner basis, is that any k-inflated copy of the skewed L n-omino has a signed tiling by skewed L n-ominoes. We also discuss regular tilings by ribbon L n-ominoes, n odd, for rectangles and more general regions. We show that in this case obstructions appear that are not detected by signed tilings.

Every Tiling of the First Quadrant by Ribbon <i>L n</i>-Ominoes Follows the Rectangular Pattern

Let and let be the set of four ribbon L-shaped n-ominoes. We study tiling problems for regions in a square lattice by . Our main result shows a remarkable property of this set of tiles: any tiling of the first quadrant by , n even, reduces to a tiling by and rectangles, each rectangle being covered by two ribbon L-shaped n-ominoes. An application of our result is the characterization of all rectangles that can be tiled by , n even: a rectangle can be tiled by , n even, if and only if both of its sides are even and at least one side is divisible by n. Another application is the existence of the local move property for an infinite family of sets of tiles: , n even, has the local move property for the class of rectangular regions with respect to the local moves that interchange a tiling of an square by n/2 vertical rectangles, with a tiling by n/2 horizontal rectangles, each vertical/horizontal rectangle being covered by two ribbon L-shaped n-ominoes. We show that none of these results are valid for any odd n. The rectangular pattern of a tiling of the first quadrant persists if we add an extra tile to , n even. A rectangle can be tiled by the larger set of tiles if and only if it has both sides even. We also show that our main result implies that a skewed L-shaped n-omino, n even, is not a replicating tile of order k2 for any odd k.

Comparative Analysis on Antenna Balun and Feeding Techniques of Step Constant Tapered Slot Antenna

This paper represents the performance analysis of the different shapes of antenna balun and feeding techniques for step constant tapered slot antenna. This work also addresses the benefits of antenna balun (circular and rectangular) along with two types of feeding techniques (Microstrip line L-shape and Microstrip line I-shape). The performance of the antenna for each technique is thoroughly investigated using Computer Simulation Technology (CST) Microwave Studio software simulation under the resonant frequency of 5.9 GHz. Results demonstrate that the proposed model is an effective tool for improving antenna performance. Moreover, an extensive comparison has been carried out between the two different shapes, with and without antenna balun and between two feeding techniques focusing on return losses, gain, directivity, and voltage standing wave ratio (VSWR).

主弯管支承成形工艺分析及模具设计

从优化工艺性分析入手,对L形零件成形优化成U形成形,介绍了凹模镶拼结构的灵活运用,对不规则厚料零件的成形有一定参考作用。