Usporedba kvalitete površine i životnog vijeka alata pri blanjanju lameliranih elemenata za prozore

The quality of the surface of wooden elements, that have been planed, has a crucial importance in the whole production process, since the obtained effects affect the quality of wooden surface after finishing (painting). The occurrence of defects is usually the reason for qualifying a workpiece as scrap or for requiring additional work. This paper presents the selected results of research of the effect of the cutting tool wear on the surface quality of elements after planing. Research experiments were conducted on the SCM Superset Class machine tool. Glulam elements of pine wood (Pinus sylvestris L.) were researched. The raw material samples (semi-finished products), 6 m long before planing, had been machined by suppliers also by planing. These workpieces were selected according to the plant requirements, e.g. their moisture content, straightness, and other defects. This paper presents the measuring results of surface roughness and some examples of surface profiles, as well as the dependence of total length of the planed elements on the type of blade material. From an economic point of view, the results showed that the use of solid carbide blades were more cost effective.Kvaliteta površine drvenih elemenata obrađenih blanjanjem ima presudnu važnost u cjelokupnome proizvodnom procesu jer kvaliteta blanjanja utječe na kvalitetu površine drva nakon završne obrade (nakon bojenja). Zbog nastalih grešaka elementi za prozore najčešće se kvalificiraju kao škart ili se moraju obaviti dodatni poslovi radi uklanjanja tih grešaka. U radu su prikazani odabrani rezultati istraživanja utjecaja zatupljenja alata na kvalitetu površine elemenata nakon blanjanja. Istraživanje je provedeno na stroju SCM Superset Class. Kao uzorci odabrani su lamelirani elementi od borovine (Pinus sylvestris L.). Uzorci lameliranih elemenata (poluproizvoda), duljine 6 m, već su prije eksperimentalnog blanjanja kod dobavljača također obrađeni blanjanjem. Ti su elementi selektirani prema zahtjevima tehnološkog procesa, npr. prema sadržaju vode, ravnosti i postojećim greškama drva. U radu su navedeni rezultati mjerenja kvalitete površine elemenata, kao i neki primjeri profila površine te ovisnost ukupne duljine oblanjanih elemenata o vrsti materijala oštrice alata. Rezultati su pokazali da je s ekonomskog stajališta isplativija uporaba alata s oštricama od tvrdog metala

Experimental and numerical investigation on the bird impact resistance of novel composite sandwich panels

Bird strikes represent a major hazard to the aerospace composite structures, due to their low impact resistance. Accurate selection and lay up of the materials in the composite structure can significantly improve the out of plane properties of the composites. However, application of the complex hybrid sandwich composites into bird strike proof structures was not investigated yet. Therefore, this work was focused on the soft body impact resistance of a novel composite design for aerospace applications. The investigation was divided into experimental and modelling parts. In the beginning of this thesis, the numerical techniques for modelling of bird im¬pact and composite materials were studied. The theoretical background for the corresponding issue was provided, followed by the thorough validation of the exist¬ing numerical approaches. A Smooth Particle Hydrodynamic (SPH) method was chosen for the modelling of the soft body. This modelling technique was validated against experimental data for the rotating fan blade. Three parametric studies of bird impacting fan blades revealed strong influence of the bird impact location and timing on the final deformed shape of the blade. Moreover, it was proved that the SPH is capable of reproducing the exact load on the structure and is appropriate technique for modelling bird strikes. [...cont.

Metoda i uređaj za 3D prikaz mikrogeometrije rezne oštrice

A very useful method was successfully applied in the investigation of tools for machining wood and wood based composites. It allows scanning of the cutting edge micro geometry in three dimensions and reproducing it in a virtual space as a 3D surface. The application of the method opens new possibilities of studying tool wear by scanning, including the calculation of volume loss and other analysis of tool wedge geometry along and perpendicularly to the cutting edge. Effectiveness of the method and scanner were successfully verified by a reference ESEM (Environmental Scanning Electron Microscopy) method.Vrlo korisna metoda skeniranja uspješno je primijenjena za istraživanje alata za obradu drva i kompozita na bazi drva. Metoda omogućuje skeniranje mikrogeometrije rezne oštrice u tri dimenzije i ponovni prikaz u virtualnom prostoru kao 3D površina. Primjena metode otvara nove mogućnosti istraživanja trošenja alata skeniranjem, uključujući izračun volumena gubitka materijala trošenjem alata ili druge analize geometrije alata uzdužno ili okomito na reznu oštricu. Učinkovitost metode i skener uspješno su verificirani uz pomoć ESEM (Environmental Scanning Electron Microscopy) metode

Surface roughness evaluation in thin EN AW-6086-T6 alloy plates after face milling process with different strategies

Lightweight alloys made from aluminium are used to manufacture cars, trains and planes. The main parts most often manufactured from thin sheets requiring the use of milling in the manufacturing process are front panels for control systems, housing parts for electrical and electronic components. As a result of the final phase of the manufacturing process, cold rolling, residual stresses remain in the surface layers, which can influence the cutting processes carried out on these materials. The main aim of this study was to verify whether the strategy of removing the outer material layers of aluminium alloy sheets affects the surface roughness after the face milling process. EN AW-6082-T6 aluminium alloy thin plates with three different thicknesses and with two directions relative to the cold rolling process direction (longitudinal and transverse) were analysed. Three different strategies for removing the outer layers of the material by face milling were considered. Noticeable differences in surface roughness 2D and 3D parameters were found among all machining strategies and for both rolling directions, but these differences were not statistically significant. The lowest values of Ra = 0.34 µm were measured for the S#3 strategy, which asymmetrically removed material from both sides of the plate (main and back), for an 8-mm-thick plate in the transverse rolling direction. The highest values of Ra = 0.48 µm were measured for a 6-mm-thick plate milled with the S#2 strategy, which symmetrically removed material from both sides of the plate, in the longitudinal rolling direction. However, the position of the face cutter axis during the machining process was observed to have a significant effect on the surface roughness. A higher surface roughness was measured in the areas of the tool point transition from the up-milling direction to the down-milling direction (tool axis path) for all analysed strategies (Ra = 0.63–0.68 µm). The best values were obtained for the up-milling direction, but in the area of the smooth execution of the process (Ra = 0.26–0.29 µm), not in the area of the blade entry into the material. A similar relationship was obtained for analysed medians of the arithmetic mean height (Sa) and the root-mean-square height (Sq). However, in the case of the S#3 strategy, the spreads of results were the lowest

Preliminary Outcomes 1 Year after Laparoscopic Sleeve Gastrectomy Based on Bariatric Analysis and Reporting Outcome System (BAROS)

# The Author(s) 2011. This article is published with open access at Springerlink.com Background The aim of this study was to assess outcomes of laparoscopic sleeve gastrectomy (LSG) as a stand-alone bariatric operation according to the Bariatric Analysis and Reporting Outcome System (BAROS). Methods Out of 112 patients included and operated on initially, 84 patients (F/M, 63:21) were followed up for 14– 56 months (mean 22±6.75). Patients lost to follow-up did not attend scheduled follow-up visits or they have withdrawn their consent. Mean age was 39 years (range 17–67; SD±12.09) with mean initial BMI 44.62 kg/m 2 (range 29.39–82.8; SD±8.17). Statistical significance was established at the p<0.05 level. Results Mean operative time was 61 min (30–140 min) with mean hospital stay of 1.37 days (0–4; SD±0.77). Excellent global BAROS outcome was achieved in 13 % of patients, very good in 30%, good in 34.5%, fair 9.5 % and failure in 13 % patients 12 months after surgery. Females achieved significantly better outcomes than males with the mean 46.5 % of excess weight loss (EWL) versus 35.3 % of EWL at 12 months (p=0.02). The mean percentage of excess weight loss (%EWL) was 43.6 % at 12 months and 46.6 % at 24 months. Major surgical complication rate was 7.1%; minor surgical complication rate 8.3%. There was one conversion (1.2%) due to the massive bleeding. Comorbidities improved or resolved in numerous patients

Global Considerations in Hierarchical Clustering Reveal Meaningful Patterns in Data

BACKGROUND: A hierarchy, characterized by tree-like relationships, is a natural method of organizing data in various domains. When considering an unsupervised machine learning routine, such as clustering, a bottom-up hierarchical (BU, agglomerative) algorithm is used as a default and is often the only method applied. METHODOLOGY/PRINCIPAL FINDINGS: We show that hierarchical clustering that involve global considerations, such as top-down (TD, divisive), or glocal (global-local) algorithms are better suited to reveal meaningful patterns in the data. This is demonstrated, by testing the correspondence between the results of several algorithms (TD, glocal and BU) and the correct annotations provided by experts. The correspondence was tested in multiple domains including gene expression experiments, stock trade records and functional protein families. The performance of each of the algorithms is evaluated by statistical criteria that are assigned to clusters (nodes of the hierarchy tree) based on expert-labeled data. Whereas TD algorithms perform better on global patterns, BU algorithms perform well and are advantageous when finer granularity of the data is sought. In addition, a novel TD algorithm that is based on genuine density of the data points is presented and is shown to outperform other divisive and agglomerative methods. Application of the algorithm to more than 500 protein sequences belonging to ion-channels illustrates the potential of the method for inferring overlooked functional annotations. ClustTree, a graphical Matlab toolbox for applying various hierarchical clustering algorithms and testing their quality is made available. CONCLUSIONS: Although currently rarely used, global approaches, in particular, TD or glocal algorithms, should be considered in the exploratory process of clustering. In general, applying unsupervised clustering methods can leverage the quality of manually-created mapping of proteins families. As demonstrated, it can also provide insights in erroneous and missed annotations

Complexity of column generation in network design with path-based survivability mechanisms

Abstract in Undeterminedhis survey deals with computational complexity of column generation problems arising in the design of survivable communication networks. Such problems are often modeled as linear programs based on noncompact multicommodity flow network formulations. These formulations involve an exponential number of path-flow variables, and therefore require column generation to be solved to optimality. We consider several path-based protection and restoration mechanisms and present results, both known and new, on the complexity of the corresponding column generation (also called pricing) problems. We discuss results for the case of single link or single node failures scenarios, and extend the considerations to multiple link failures. Further, we classify the design problems corresponding to different survivability mechanisms according to the structure of their pricing problem. Eventually, we show that almost all the encountered pricing problems are hard to solve for scenarios admitting multiple failures, while a great deal of them are NP-hard already for single failure scenarios

SNDlib 1.0 - survivable network design library

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