基于OR-Tools的某市高校蔬菜配送路径优化

车辆路径优化问题是运营研究中的一个重要领域,其目的是降低配送成本、提高配送效率。本文以某市高校蔬菜配送车辆路径优化问题为案例,研究如何使用OR-Tools开源软件库来解决这个问题。首先,本文分析了某市高校蔬菜配送车辆的现实需求,包括行驶距离、需求量、车辆容量、数量等参数。在此基础上,建立了一个车辆路径优化模型,旨在最小化车辆总行驶距离或成本,同时满足车辆容量、配送高校顺序等约束条件。其次,使用Python3.8编写代码,借助OR-Tools以及matplotlib分析求解此模型;在求解模型过程中,本文针对某市高校蔬菜配送数据集进行测试。结果表明,其方法能够有效地减少配送车辆的行驶距离和降低配送成本。由此,本文利用OR-Tools软件库成功地研究某市高校蔬菜配送车辆路径优化问题,为实际物流配送提供了有效的决策支持。

文旅融合政策创新体系研究——基于中央政策文本的“主体-路径-工具”三维框架分析

机构改革开启了文旅融合政策创新的新篇章,中央发布的文旅融合政策对地方政策创新和行业实践发挥“风向标”作用,但学界一般关注的是文化旅游政策,而非融合相关政策,也鲜少以一个立体化的研究框架去分析其结构和关联特征。文章以中央政策文本为例,构建了“政策主体-融合路径-政策工具”三维框架,研究有以下发现。(1)文旅融合政策创新主体以文化和旅游部、国家发展和改革委员会以及财政部等部门为主,发文方式独立创新为主、合作创新为辅。政策文件的主体属性包括单核、多核、单边等6种。(2)融合路径存在偏好性,以体制融合、业态融合和产品融合为主,其中,政策支撑、产业融合类型和高品质文旅产品等细分类别较为突出,其他路径政策内容相对较少。(3)政策工具的使用具有倾向性,以供给型为主、环境型为辅,需求型最少,其中,产业培育、目标定位、示范试点和公共服务是较为重要的工具类别。(4)文旅融合政策创新共有386条创新路径,提炼出6类典型政策创新路径。政策创新逻辑是以核心层部门为主,从体制、产品和业态等融合路径,调动供给型、环境型工具促进文旅融合。该研究进一步提出制定文旅融合专项政策、加强主体合作、优化融合路径和均衡政策工具4点政策优化建议,具有一定的理论意义和实践价值。

Tool Positioning Algorithm Based on Smooth Tool Paths for 5-axis Machining of Sculptured Surfaces

The current research of the 5-axis tool positioning algorithm mainly focuses on searching the local optimal tool position without gouging and interference at a cutter contact（CC） point,while not considering the smoothness and continuity of a whole tool path.When the surface curvature varies significantly,a local abrupt change of tool paths will happen.The abrupt change has a great influence on surface machining quality.In order to keep generated tool paths smooth and continuous,a five-axis tool positioning algorithm based on smooth tool paths is presented.Firstly,the inclination angle,the tilt angle and offset distance of the tool at a CC point are used as design variables,and the machining strip width is used as an objective function,an optimization model of a local tool positioning algorithm is thus established.Then,a vector equation of tool path is derived by using the above optimization model.By analyzing the equation,the main factors affecting the tool path quality are obtained.Finally,a new tool position optimization model is established,and the detailed process of tool position optimization is also given.An experiment is conducted to machine an aircraft turbine blade by using the proposed algorithm on a 5-axis blade grinding machine,and the machined blade surface is measured with a coordinate measuring machine（CMM）.Experimental and measured results show that the proposed algorithm can ensure tool paths are smooth and continuous,improve the tool path quality,avoid the local abrupt change of tool paths,and enhance machining quality and machining efficiency of sculptured surfaces.

OPTIMAL ALGORITHM FOR NO TOOl-RETRACTIONS CONTOUR-PARALLEL OFFSET TOOL-PATH LINKING

A contour-parallel offset （CPO） tool-path linking algorithm is derived without toolretractions and with the largest practicability. The concept of ＂tool-path loop tree＂ （TPL-tree） providing the information on the parent/child relationships among the tool-path loops （TPLs） is presented. The direction, tool-path loop, leaf/branch, layer number, and the corresponding points of the TPL-tree are introduced. By defining TPL as a vector, and by traveling throughout the tree, a CPO tool-path without tool-retractions can be derived.

Development of tool-path generation module for 5-axis control machining of impellers

An impeller is difficult to machine because of severe collision due to the complex shape,overlapping and twisted shape of the impeller blades.So,most computer aided manufacturing(CAM)software companies have developed CAM module for manufacturing impeller according to their CAM software.But these dedicated modules are difficult to use for inexperienced users.The purpose of this work is to develop a tool-path generation module for impellers.For this purpose,it is based on Visual Basic language and used CATIA graphical environment.The result of simulation for generated tool-path by the module is satisfactory.And it has slow processing speed compared to other commercial modules,but it is easy to use.

GENERATE ROUGH TOOL-PATHS FROM UNORGANIZED POINT-CLOUD DIRECTLY

An approach is presented to generate rough interference-free tool-paths directly from massive unorganized data in rough machining that is performed by machining volumes of material in a slice-by-slice manner. Unorganized point-cloud is firstly converted to cross-section data. Then a robust data-structure named tool-path net is constructed to save tool-path data. Optimal algorithms for partitioning sub-cut-areas and computing interference-free cutter-locations are put forward. Finally the tool-paths are linked in a zigzag milling mode, which can be transformed into a traveling sales man problem. The experiment indicates optimal tool paths can be acquired, and high computation efficiency can be obtained and interference can be avoided successfully.

A new iso-scallop height tool path planning method in three-dimensional space

This paper presents a new approach for designing the tool paths in the machining of sculptured surfaces for computer nu- merical controlled end milling. In the proposed method, the tool paths are determined so that the scallop height formed by two adja- cent machining paths is maintained constant across the machined surface. Unlike previous work on iso-scallop height milling, the present work considers the true 3D configuration of the milling procedure and can be used to generate better results, which is shown by examoles.

Tool path generation of ultra-precision diamond turning: A state-of-the-art review

With the increasing market demand for optical complex surface parts,the application of multi-axis ultraprecision single-point diamond turning is increasing.A tool path generation method is very important to decrease manufacturing time,enhance surface quality,and reduce cost.Compared with the tool path generation of the traditional multi-axis milling,that of the ultra-precision single-point diamond turning requires higher calculation accuracy and efficiency.This paper reviews the tool path generation of ultra-precision diamond turning,considering several key issues:cutter location(CL)points calculation,the topological form of tool path,interpolation mode,and G code optimization.

Cutter Accessibility Map and Its Application for 5-axis Milling Tool-path Generation

In tool-path generation process for 5-axis face milling,the specification of cutter posture is one of the critical issues that contribute to the computation load. In this paper,a quick algorithm is presented to specify the cutter posture at a surface point based on the cutter’s accessibility maps (A-maps) at all the sampled points,obtained during cutter selection. Integrated with this quick algorithm,an efficient approach is proposed to generate a set of iso-planar tool-paths for finishing a given surface withmaximum machining efficiency without violating the desirable profile and scallop height tolerance. One example is given to confirm the validity of the quick algorithm for cutter posture and the efficiency of the algorithm for tool-path generation.

A Tool Path Re-generation Algorithm for Die & Mold Machining

Facing the challenges of a shorter product design a nd manufacturing lead-time, many mold companies are using 3-D CAD/CAM software s ystems in design and manufacturing. A new product file is often issued to the mo ld design department before it is completely finalized and the design may have t o be iterated many times during the mold design and making processes. In practic e, if a mold has been modified, all the tool paths that cover the modified regio n must be re-generated, no matter how small the modified region may be. With th e available tool path generation systems, if a tool path needs to be re-generat ed, all the cutter location (CL) points must be re-calculated, and none of the original CL points can be re-used. It would require as much time to re-gen erate the modified tool path as in the original case. On the other hand, the mod ified region is usually quite small compared with the entire mold. The complete re-generation process is therefore highly unproductive and time-consuming. This paper proposes an efficient tool path re-generation approach for 3-axis d ie and mold machining. It is assumed in this research that a gouge-free too l path has been generated for the original mold and the same ball end-mill is to be used to generate the tool path for the modified mold. It is shown in th is work that if the boundary of the modified region is interference-free, the a ffected CL points are enclosed by a set of CL points which correspond to the poi nts on the boundary of the modified region. An efficient tool path re-generatio n algorithm was developed in this research. With this algorithm, a closed CL cur ve is first generated from the boundary of the affected region. The CL points fo r the original mold are then analyzed by comparing the x and y values with the b oundary of the affected CL points. If the CL points are not affected by the modi fication, they are output to the new CL file directly. Otherwise, they are remov ed and replaced by the new CL points. The algorithm has been tested using severa l industrial parts, and results show that it is efficient, robust, and the re-g enerated tool path is gouge-free and smooth.

TOOL PATH OPTIMIZATION OF POCKET CORNER

In milling around sharp corners, residual materials are left at sharp corners when the stepover is extremely long in the contour-parallel tool path. Milling force at the sharp corner rises momentarily due to the increase of the cutter contact length, thus shortening the tool life and leading to machine chatter, even cutter breakage. Then a tool path improvement method by inserting biarc transition segments in the contour-parallel tool path is proposed for milling the pocket. Using the method, the cutter moves along the biarc transition tool path. And the corner material is removed. The improved tool path is continuous for clearing residual materials at the sharp corner. Finally, the machining experiment validates the proposed method.

REALIZATION OF ALGORITHM OF TOOL PATH GENERATION FOR NC MACHINING OF MOLAR PROSTHESIS

The CAD model of molar prosthesis is usually stored in standard templete library （STIr） format. A new topological structure is given based on STL format and the vertex-based entity offset algorithm is presented to realize the rapid generation of roughing/finishing tool path for molar prosthesis. Simulation results show that the proposed algorithm prossesses characteristics of excellent stabilization, fast calculation speed and high machining accuracy.

基于Preston-PSO算法的多方向机器人磨抛轨迹生成方法

针对机器人磨抛加工过程中的纹理现象,提出一种基于Preston公式和粒子群优化算法的多方向性机器人磨抛加工轨迹生成方法,获得能自适应曲面模型的光顺无拐角、覆盖均匀且具有多方向性的磨抛加工轨迹。仿真与实验证明,与方向平行轨迹的加工效果相比,此算法生成的轨迹能有效抑制表面条形加工纹理的产生,减小加工表面粗糙度,提高表面质量,获得良好的镜面加工效果。

Efficient cutting path planning for a non-spherical tool based on an iso-scallop height distance field

Iso-scallop height machining means,when machining a freeform surface,the scallop height between any two neighboring tool paths on the surface will be a constant(i.e.,the given threshold),which is preferable among various freeform surface machining strategies due to its high machining efficiency as well as better machine tool’s dynamics.However,all the existing iso-scallop height path planning methods pertain to only the ball-end or flat-end types of tools.In recent years,the non-spherical cutting tool has become more and more popular,especially for five-axis machining of complex freeform surfaces,majorly owing to its non-constant curvature which can be utilized to adaptively fit the tool to the surface to both avoid the local gouging and enlarge the cutting width.However,there have been no reported works on iso-scallop height five-axis tool path generation for a non-spherical tool,and,in this paper,we present one.Specifically,we first define and construct two fields on the surface to be machined-the collision-free tool orientation field(vector)and the iso-scallop height distance field(scalar).The iso-lines of the scalar field and their associated tool orientation field vectors then naturally serve as potential iso-scallop height five-axis tool paths,and we present a propagation-based algorithm to construct the desired tool path from the iso-lines.The computer simulation and physical cutting experiments confirm that everywhere on the surface,except maybe near the saddle curves of the scalar filed,the scallop height is exactly the given thresh-old.By adding the saddle curves as extra tool paths,the final machined surface then is assured of the required scallop height requirement.

TOOL PATH PLANNING USING VORONOI DIAGRAM AND THREE STACKS

Based on the object oriented data structure of Voronoi diagram, the algorithm of the trimmed offset generating and the optimal too l path planning of the pocket machining for multiply connected polygonal domains are studied. The intersection state transition rule is improved in this algorithm. The intersection is between the trimmed offsets and Voronoi polygon. On this basis, the trimmed offset generating and the optimal tool path planning are mad e with three stacks(I stack, C stack and P stack)in different monotonous pouches of Voronoi diagram. At the same time, a merging method of Voronoi diagram an d offsets generating for multiply connected polygonal domains is also presented. The above algorithms have been implemented in NC machining successfully, and the efficiency is fully verified.

Theoretical and Experimental Research on Error Analysis and Optimization of Tool Path in Fabricating Aspheric Compound Eyes by Precision Micro Milling

Structure design and fabricating methods of three-dimensional （3D） artificial spherical compound eyes have been researched by many scholars. Micro-nano optical manufacturing is mostly used to process 3D artificial compound eyes. However, spherical optical compound eyes are less at optical performance than the eyes of insects, and it is difficult to further improve the imaging quality of compound eyes by means of micro-nano optical manufacturing. In this research, nonhomogeneous aspheric compound eyes （ACEs） are designed and fabricated. The nonhomogeneous aspheric structure is applied to calibrate the spherical aberration. Micro milling with advantages in processing three-dimensional micro structures is adopted to manufacture ACEs. In order to obtain ACEs with high imaging quality, the tool paths are optimized by analyzing the influence factors consisting of interpolation allowable error, scallop height and tool path pattern. In the experiments, two kinds of ACEs are manufactured by micro-milling with different too path patterns and cutting parameter on the miniature precision five-axis milling machine tool. The experimental results indicate that the ACEs of high surface quality can be achieved by circularly milling small micro-lens individually with changeable cutting depth. A prototype of the aspheric compound eye （ACE） with surface roughness （Ra） below 0.12 p.m is obtained with good imaging performance. This research ameliorates the imaging quality of 3D artificial compound eyes, and the proposed method of micro-milling can improve surface processing quality of compound eyes.

TOOL PATH GENERATION BASED ON STL FILE FOR SHEET METAL DIELESS FORMING

Sheet metal dieless forming is a new metal forming technology. Thistechnology adopts the principle of rapid prototyping technology, so it can form sheet metal partswithout traditional die and moulds. According to the characteristic of sheet metal dieless formingtechnology a new way of tool path generation based on the STL file for sheet metal dieless formingis proposed.

Global Tool Path Fairing Algorithm for Automated Fiber Placement

A global energy fairing method,applied to automated fiber placement(AFP)tool path,was proposed.The main purpose was to improve the adaptability of AFP path towards part with sharp curvature variation as well as product quality.The relation between path geometric property and manufacturing property was discussed and a series of experiments were carried out.Based on cubic B-Spline global fairing method,the AFP tool path was faired which decreased the tool path curvature and curvature changing rate.Compared with initial ones,the path faired by the proposed method was relatively flat and smooth,which contributed to layup efficiency and reducing bulking defects.The method was demonstrated potentials in application for AFP manufacturing,especially for aeronautic and aerospace industry practice.

Preliminary research on the transmission path of nssSO_4^(2-) and NO_3^- in Antarctic ice sheet

The main sources of nssSO 2- 4 and NO - 3 were summarized in this paper. By analyzing the spatial distribution features of major ions in Antarctic ice sheet and studying on the different time of the same volcanic event recorded by different ice cores from different regions in Antarctica, this paper intends to study the transmission path of nssSO 2- 4 and NO - 3. Results show that nssSO 2- 4 and NO - 3 are transmitted to the ice sheet through long distance and high altitude. The procedure of the transmission is that nssSO 2- 4 and NO - 3 are transmitted to the level between the top of troposphere and the bottom of stratosphere, then subsided to the ice sheet surface and spread to other regions.

Generation of tool path for flank milling in divided areas

Presents the division of non developable ruled surface into divided small areas and flank milling in these divided areas to improve machining efficiency and machined surface quality by controlling the machining error for each area, and the algorithms developed for generation of tool path and calculation of errors, and concludes from computer simulation results that the algorithms are correct.