Zone design of specific sizes using adaptive additively weighted voronoi diagrams

Territory or zone design processes entail partitioning a geographic space, organized as a set of areal units, into different regions or zones according to a specific set of criteria that are dependent on the application context. In most cases, the aim is to create zones of approximately equal sizes (zones with equal numbers of inhabitants, same average sales, etc.). However, some of the new applications that have emerged, particularly in the context of sustainable development policies, are aimed at defining zones of a predetermined, though not necessarily similar, size. In addition, the zones should be built around a given set of seeds. This type of partitioning has not been sufficiently researched; therefore, there are no known approaches for automated zone delimitation. This study proposes a new method based on a discrete version of the adaptive additively weighted Voronoi diagram that makes it possible to partition a two-dimensional space into zones of specific sizes, taking both the position and the weight of each seed into account. The method consists of repeatedly solving a traditional additively weighted Voronoi diagram, so that each seed?s weight is updated at every iteration. The zones are geographically connected using a metric based on the shortest path. Tests conducted on the extensive farming system of three municipalities in Castile-La Mancha (Spain) have established that the proposed heuristic procedure is valid for solving this type of partitioning problem. Nevertheless, these tests confirmed that the given seed position determines the spatial configuration the method must solve and this may have a great impact on the resulting partition

MSEC/ICMMP2008-72258 LASER POLISHING PARAMETER OPTIMIZATION FOR DIE AND MOULDS SURFACE FINISHING MSEC_ICM&P2008-72258

ABSTRACT Final polishing operation for die and mould manufacturing represents up to 30% of the total manufacturing cost and it is a high added value operation carried out manually by qualified personnel. The work presented in this paper proposes an automated solution for this task by the process known as Laser Polishing. This process is based on the application of a laser beam melting a microscopic layer of material, which lately solidifies filling the gaps, and smoothing the overall topography. Several Laser Polishing tests have been done with CO 2 and High Power Diode Lasers (HPDL) on two different materials commonly used in die and mould industry: a DIN 1,2379 Tool Steel tempered up to 62HRC, used for injection moulds inserts, and a spheroidal graphite Cast Iron DIN GGG70L used typically on large stamping dies manufacturing. By means of the tests and Design of Experiments (DoE) technique, the operation parameters for the Laser Polishing process as well as its degree of influence in the melted surface have been defined. Starting off from an initial surface obtained by means of High Speed Milling operation, it has been possible to obtain satisfactory results with final roughness reductions higher than 80% with respect to the initial values, and mean roughness values below 0.8µm Ra. INTRODUCTION Actually the use of laser in the industry is almost limited to operations of cutting and welding. However, a new generation of lasers is extending the possible applications to fields like microtechnology, industry and other strategic areas One of the most emergent processes at the moment in the industry is the laser surface heat treatment and laser texturing. The development of new kind of lasers and the high requirements in the manufacturing of high added value parts makes the manufacturer consider the laser technology in spite of its high cost. Focusing on laser texturing process, it consists on the local vaporisation of material by means of the application of a relatively high energy laser beam, improving surface mechanical functionality, tribology or even aesthetic. The laser texturing process allows diverse types of applications, such as the friction reduction between cylinder and piston rings in combustion engine

Approximate Solutions of Delay Differential Equations with Constant and Variable Coefficients by the Enhanced Multistage Homotopy Perturbation Method

We expand the application of the enhanced multistage homotopy perturbation method (EMHPM) to solve delay differential equations (DDEs) with constant and variable coefficients. This EMHPM is based on a sequence of subintervals that provide approximate solutions that require less CPU time than those computed from the dde23 MATLAB numerical integration algorithm solutions. To address the accuracy of our proposed approach, we examine the solutions of several DDEs having constant and variable coefficients, finding predictions with a good match relative to the corresponding numerical integration solutions

Feature extraction-based prediction of tool wear of Inconel 718 in face turning

Tool wear is a recurring topic in the cutting field, so obtaining knowledge about the tool wear process and the capability of predicting tool wear is of special importance. Cutting processes can be optimised with predictive models that are able to forecast tool wear with a suitable level of accuracy. This research focuses on the application of some regression approaches, based on machine learning techniques, to a face-turning process for Inconel 718. To begin with, feature extraction of the cutting forces is considered, to generate regression models. Subsequently, the regression models are improved with a reduced set of features obtained by computing the feature importance. The results provide evidence that the gradient-boosting regressor allows an increment in the wear prediction accuracy and the random forest regressor has the capability of detecting relevant features that characterise the turning process. They also reveal higher accuracy in predicting tool wear under high-pressure cooling as opposed to conventional lubrication.The work was performed as a part of the HIMMOVAL project (grant agreement number: 620134) within the Clean Sky programme, which relates to the SAGE2 project oriented to geared open rotor development, enabling the delivery of the demonstrator part. The work of Roberto Santana has been funded by the IT-609-13 programme (Basque Government) and TIN2016-78365-R (Spanish Ministry of Economy, Industry and Competitiveness)

Entrepreneurial research model, CIC marGUNE: A case study

272-276This paper presents an entrepreneurial research model, CIC marGUNE. Technological research agencies and universities work with Basque industries in CIC marGUNE under sponsorship of local government for developing and refining contemporary industrial manufacturing processes. Proposed paradigms and functional structure will benefit other developing regions of similar size, population and industrial economy

Effect of WEDM Process Parameters on Surface Morphology of Nitinol Shape Memory Alloy.

Nickel-titanium shape memory alloys (SMAs) have started becoming popular owing to their unique ability to memorize or regain their original shape from the plastically deformed condition by means of heating or magnetic or mechanical loading. Nickel-titanium alloys, commonly known as nitinol, have been widely used in actuators, microelectromechanical system (MEMS) devices, and many other applications, including in the biomedical, aerospace, and automotive fields. However, nitinol is a difficult-to-cut material because of its versatile specific properties such as the shape memory effect, superelasticity, high specific strength, high wear and corrosion resistance, and severe strain hardening. There are several challenges faced when machining nitinol SMA with conventional machining techniques. Noncontact operation of the wire electrical discharge machining (WEDM) process between the tool (wire) and workpiece significantly eliminates the problems of conventional machining processes. The WEDM process consists of multiple input parameters that should be controlled to obtain great surface quality. In this study, the effect of WEDM process parameters on the surface morphology of nitinol SMA was studied using 3D surface analysis, scanning electron microscopy (SEM), and energy-dispersive X-ray (EDX) analysis. 3D surface analysis results indicated a higher value of surface roughness (SR) on the top of the work surface and a lower SR on the bottom portion of the work surface. The surface morphology of the machined sample obtained at optimized parameters showed a reduction in microcracks, micropores, and globules in comparison with the machined surface obtained at a high discharge energy level. EDX analysis indicated a machined surface free of molybdenum (tool electrode)

Preventing chatter vibrations in heavy-duty turning operations in large horizontal lathes

Productivity and surface finish are typical user manufacturer requirements that are restrained by chatter vibrations sooner or later in every machining operation. Thus, manufacturers are interested in knowing, before building the machine, the dynamic behaviour of each machine structure with respect to another. Stability lobe graphs are the most reliable approach to analyse the dynamic performance. During heavy rough turning operations a model containing (a) several modes, or (b) modes with non-conventional (Cartesian) orientations is necessary. This work proposes two methods which are combined with multimode analysis to predict chatter in big horizontal lathes. First, a traditional single frequency model (SFM) is used. Secondly, the modern collocation method based on the Chebyshev polynomials (CCM) is alternatively studied. The models can be used to identify the machine design features limiting lathe productivity, as well as the threshold values for choosing good cutting parameters. The results have been compared with experimental tests in a horizontal turning centre. Besides the model and approach, this work offers real worthy values for big lathes, difficult to be got from literature.Basque Country Government, GAITEK program

Wear and MnS Layer Adhesion in Uncoated Cutting Tools When Dry and Wet Turning Free-Cutting Steels

Free-cutting steels are developed to produce large quantities of parts with low mechanical behavior, mainly for automotive sector. These alloys contain phosphorous, lead, sulfur, and manganese that help to improve the machinability and surface roughness. However, due to the toxicity of lead, steel mills in recent years have been focusing on non-toxic steels to produce minimum environmental pollution and better machinability. The present work investigates the tool wear during dry and wet turning of free-cutting steels (SAE 1212, SAE 12L14, and SAE 1215) by using uncoated hard metal inserts at three cutting speeds. Additionally, a EDS analysis was performed to determine the presence of Mn and S elements at the rake face of the cutting tool that can induce a higher adhesion of manganese sulfide (MnS). The results show that the SAE 12L14 steel has the best performance in terms of tool life at different cutting speeds. This difference is maximum at the lowest cutting speed, which gradually decreases with the increase of the cutting speed. The wear behavior is evaluated in the three steel alloys at each cutting speed and, consequently, the tool wear exhibits a slightly better performance in the dry machining condition for higher cutting speeds (180 and 240 m/min), independent of the steel alloy. Finally, EDS analysis confirms the presence of Mn and S elements at the rake face of the inserts machined in dry condition. Hence, MnS is expected to interpose between the machined surface and cutting tool surface to behave similar to tribofilm by reducing the wear on the cutting edge