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No. of bitstreams: 1 nacata_g_me_jabo.pdf: 2786616 bytes, checksum: 67b7659d3b90cd80d278a073d130a20c (MD5) Previous issue date: 2017-01-27 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / O cultivo de jambeiro pode ser fonte de diversificação da atividade agrícola, visto que suas características físicas e qualitativas são atrativas para os consumidores. Tendo como origem o Continente Asiático, os jambeiros vermelho, amarelo e rosa apresentam características que viabilizam sua comercialização no território nacional. No entanto, é notável a carência de estudos sobre as três espécies citadas. O presente trabalho objetivou, desta forma, trazer maiores informações sobre as três espécies de jambeiro, estudando a propagação por sementes e por estaquia, descrição morfológica do processo germinativo e dos grãos de pólen, verificando viabilidade polínica e estigmática, caracterização biométrica de frutos, folhas e sementes, além de caracterização qualitativa de seus frutos. Os resultados evidenciam que o jambeiro amarelo apresenta maior taxa de germinação e poliembrionia. As temperaturas influenciam na porcentagem de germinação, poliembrionia e IVG. para os jambeiros vermelho e amarelo. As sementes apresentam cotilédones de coloração verde, germinação hipógea com raiz primária de coloração marrom e secundárias esbranquiçadas, curtas e filiformes. Para a estaquia, visando otimização do processo e redução de gastos, a utilização de ácido indolbutírico (AIB) se torna dispensável e a manutenção das folhas inteiras nas estacas promove aumento do comprimento e número médio de raízes. O jambeiro vermelho tem massa de fruto entre 35,06 a 56,20(g); semente entre 11,55 a 16,05 (g); comprimento e largura dos frutos entre 4,93 a 5,91(cm) e 3,98 a 4,77(cm); largura das sementes entre 2,86 a 3,44(cm). O jambeiro rosa apresenta máxima porcentagem de polpa, e parâmetros iguais ao vermelho quanto comprimento, largura da folha e comprimento do pecíolo e área foliar. O Jambeiro amarelo é o menor entre os estudados. Existem diferenças na morfologia polínica para as três espécies estudadas, observa-se que o S. jambos é a espécie de maior tamanho no diâmetro polar e equatorial, S. aqueum apresenta maior diâmetro polar, em relação ao S. malaccense, e a última citada com menor diâmetro polar e equatorial quando comparada com as outras espécies. O teste de viabilidade do pólen permite concluir que as espécies de jambeiros (amarelo e rosa) que florescem no mesmo período podem competir pelos mesmos agentes polinizadores em função dos horários de disponibilidade de pólen e receptividade do estigma. Para a análise qualitativa dos frutos verifica-se que existem diferenças entre as espécies analisadas, sendo que os frutos dos jambeiros vermelho e rosa apresentam: aumento da massa, diminuição da firmeza, maior cromaticidade, aumento de sólidos solúveis, diminuição da acidez titulável, aumento do pH, aumento do ácido ascórbico e da respiração conforme atingem maior grau de maturação. Os frutos do jambeiro vermelho têm um teor quatro vezes mais baixo de ácido ascórbico e sua respiração é alterada conforme o grau de maturação do fruto, quando comparado ao jambeiro rosa, que não se altera. / The cultivation of Syzygium can be a source of diversification of the agricultural activity, since its physical and qualitative characteristics are attractive for the consumers. Having as origin the Asian Continent, the malay, rose and water apple present characteristics that allow their commercialization in the national territory. However, the lack of studies on the three species mentioned is remarkable. The present work aimed to provide more information about the three species of Syzygium, studying seed propagation and cutting, morphological description of the germination process and pollen grains, pollen and stigmatic viability, biometric characterization of fruits, leaves and seeds, besides qualitative characterization of its fruits. The results show that the rose apple presents a higher rate of germination and polyembryony. Temperatures influence the percentage of germination, polyembryony and Germination Speedy Index (GSI). For the malay and rose apple. The seeds present green color cotyledons, hygienic germination with primary root of brown coloration and whitish secondary, short and filiform. For cutting, for optimization of the process and reduction of expenses, the use of indolbutyric acid (AIB) becomes dispensable and the maintenance of the whole leaves on the cuttings promotes an increase in the length and average number of roots. The malay jamb has a fruit mass between 35.06 and 56.20 (g); Seed between 11.55 and 16.05 (g); Length and width of fruits between 4.93 to 5.91 (cm) and 3.98 to 4.77 (cm); Seed width from 2.86 to 3.44 (cm). The water apple presents maximum percentage of pulp, and parameters equal to red as length, leaf width and petiole length and leaf area. The rose apple is the smallest among those studied. There are differences in pollen morphology for the three species studied, it is observed that S. jambos is the largest species in the polar and equatorial diameter, S. aqueum has a larger polar diameter, in relation to S. malaccense, and the last one mentioned with smaller polar and equatorial diameter when compared with the other species. The pollen feasibility test allows to conclude that rose apple and water apple that bloom in the same period can compete for the same pollinating agents depending on the pollen availability schedules and stigma receptivity. For the qualitative analysis of the fruits it is verified that there are differences between the analyzed species, with the fruits of the malay and water apple present: increase of mass, decrease of firmness, greater chromaticity, increase of soluble solids, decrease of titratable acidity, increase of pH, increase of ascorbic acid and respiration as they reached a higher degree of maturation. The fruits of the malay apple have a four times lower content of ascorbic acid and their respiration is altered according to the degree of maturation of the fruit when compared to the water apple, which does not change.

El texto completo de este trabajo no está disponible en el Repositorio Académico UPC por restricciones de la casa editorial donde ha sido publicado. / In recent years, homegrown SMEs have had low production levels when compared with Chinese garment imports, losing their competitive advantage in the domestic market. SMEs represent 96% of garment companies in Peru and have a positive impact on the creation of jobs. The search for a technique to improve SME output was conducted in various studies; however, the efforts did not bear fruit over time. Thus, this article seeks to improve the low production efficiency in textile and clothing SMEs. Therefore, we proposed a model and validated it in the production area of a denim clothing manufacturing company in Peru. We conducted business diagnostics and found a production efficiency problem. Later, we adapted the Lean production management model to the prevailing organizational culture. The main result was that the company's production efficiency increased from 68% to 71%. Finally, employee commitment, along with the combination of the Lean model and organizational culture, allowed the improvements to stand the test of time after their implementation.

Laser cutting is a widely used technology for precision cutting of various materials, in-cluding mild structural steel. It involves the use of a high-powered laser beam to melt, burn, or vaporize the material, resulting in a clean and accurate cut. This doctoral thesis presents a comprehensive investigation of the laser cutting process for mild structural steels. To understand the thermal effects on the steel workpiece, an analytical model for the laser cutting heat source is proposed, which takes into account laser source geometry variation along the cut edge thickness. A modified heat source based on a Gaussian dis-tribution is used to model the heat flux as a combination of laser beam and heat produced by the reaction of oxygen with iron. The proposed model allows the laser cutting process to be simulated as a function of cutting speed, laser power, and shape of the heat flux. The FE method is employed to predict both temperature and stress fields in the cutting section considering the solid-state phase transformation during and after the laser cutting process. Optical microscopy, scanning electron microscopy and microhardness measure-ments are employed to observe morphological and metallurgical changes in the cutting sections, and the stress is detected using the X-ray diffraction methodology. The residual stress field surrounding the cutting edges is experimentally examined, and the results are compared to those anticipated by the developed model. An accurate temperature distri-bution field is obtained and validated by microstructural solid phases of the cut specimens. Consequently, residual stresses are also validated by comparing experimental measure-ments and outputs of the FE model. The study also investigates the optimization of laser cutting parameters for achieving, in agreement with the standard EN ISO 9013, quality cut surface requirements, such as roughness and perpendicularity. The trial-and-error method used in the past is incompat-ible with environment-friendly processes. Hence, to study the effects of cutting parameters on the target parameters and to collect data, an experimental campaign is carried out on a 12 mm thickness low carbon steel grade S235 cut by a 4kW fiber laser. A multi-objective optimization based on both a genetic algorithm and Kriging method is carried out to in-vestigate the correlations between input and target parameters as well as to find the op-timal laser cutting parameters to achieve the minimum roughness and perpendicularity. The applicability of the Kriging method to laser cutting processes is highlighted by the agreement between predicted cut quality and experimental results, provided by additional specimens cut with laser parameter sets obtained by a Pareto front. Overall, the investi-gated model offers important details on the physical procedures that occur during the laser cutting process and provides useful insights for selecting the optimal sets of laser cutting parameters for different applications.

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第22438号 / 工博第4699号 / 新制||工||1734(附属図書館) / 京都大学大学院工学研究科マイクロエンジニアリング専攻 / (主査)教授 松原 厚, 教授 西脇 眞二, 教授 小森 雅晴 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

<p>Finite element analysis (FEA) employs a science-based approach in which the complete machining process can be simulated and optimized before resorting to costly and time-consuming experimental trials. In this work, cutting coefficient of AISI 1045 steel will be estimated using finite element modelling using Arbitrary Lagrangian Eulerian formulation (ALE). The estimated values are then experimentally validated. A parametric study is carried out after in order to investigate how some cutting parameters can affect the cutting coefficients. The process parameters to be varied include feed rate, cutting speed, and cutting edge radius.</p> / Master of Applied Science (MASc)

The fully fashioned master’s thesis within the frame of the master’s study at the Fakulty of mechanical engineering deals with subject woodworking tools. There are characteristics of wood and tool materials used for woodworking. There is an emphasis on milling cutter in each case of construction of selected woodworking tools. Whereas there is concrete proposal of milling cutter used for production of half round profile – half round concave cutter – at the end of the thesis.

There are several ways to cut down a tree. The piece by piece cutting method is studied in this research. By modeling the cutting process into simple dynamic models and obtaining governing equations of motion of tree and cut piece in each model, the forces during cutting process were calculated. The method was then applied to a set of real data and tree vibrations were compared with field measurements. The study is very rare in the case of the variety of the topics it covers from dynamics and mechanics to finite element modeling of a biological system.

<p>Predmet istraživanja prikazanih u okviru doktorske diseracije su samopobudne vibracije pri obradi glodanjem. Na osnovu detaljne analize zakonitosti nastanka samopobudnih vibracija uspostavljena je određena paralela između glodanja i mikrogkodanja, za slučajeve kada je dubina rezanja veća od radijusa rezne ivice alata. Za tako usvojene pretpostavke, razvijeni su modeli unapređene numeričke simulacije procesa glodanja i mikroglodanja. Razvijeni modeli su svestrano verifikovani, s jedne strane, u segmentima gde postoje podaci u literaturi; poređenjem sa rezultatima drugih autora, a sa druge strane poređenjem sa sopstvenim eksperimentalnim ispitivanjima. Za eksperimentalno definisanje granične dubine rezanja pri glodanju predložena je inovativna metoda tangenti, a pri mikroglodanju, imajući u vidu raspoloživu mernu opremu, metoda hrapavosti obrađene površine. Matematički modeli i eksperimentalne metode su verifikovani pri obradi tri karakteristične vrste materijala i na dva obradna sistema pri glodanju, odnosno jednom materijalu i jednom obradnom sistemu pri mikroglodanju. Rezultati istraživanja su prezentovani kroz dvanaest poglavlja čiji sadržaj se navodi u nastavku.</p><p>U prvom, uvodnom poglavlju, ukazano je na značaj istraživanja samopobudnih vibracija pri makro i mikroglodanju. Prikazana je i aktuelnost istraživanja analizom broja naučnih radova koji se bave problematikom samopobudnih vibracija u periodu od poslednjih dvadeset pet godina.<br />Kroz drugo poglavlje detaljno su prikazana dosadašnja istraživanja samopobudnih vibracija pri makroglodanju, dok su u trećem poglavlju prikazana istraživanja samopobudnih vibracija pri mikroglodanju. Izvršena je analiza uticajnih parametri na graničnu dubinu rezanja, koja predstavlja osnovni pokazatelj dinamičke stabilnosti kako makro, tako i mikroobradnih sistema.<br />Na osnovu saznanja prikazanih u okviru drugog i trećeg poglavlja u četvrtom poglavlju su definisani ciljevi i hipoteze istraživanja.<br />Matematičke metode za definisanje karte stabilnosti obradnog sistema, prikazane su u petom poglavlju. Prikazana su dva matematička modela za definisanje karte stabilnosti pri makroglodanju, model srednjeg ugla kontakta alata u zahvatu i model Furijeovih redova. Prezentovana je numerička simulacija procesa obrade glodanjem, namenjena prvenstveno za simulaciju sila rezanja. Polazeći od prethodno prikazane ideje u okviru ovog poglavlja je razvijena nova matematička metoda predikcije granične dubine rezanja - unapređena numerička simulacija procesa glodanja.<br />U okviru šestog poglavlja prikazane su eksperimentalne metode identifikacije vibracija mašina alatki, odnosno eksperimentalno određivanje modalnih parametara obradnih sistema kao i metode detekcije samopobudnih vibracija pri glodanju. U cilju definisanja granične dubine rezanja, prikazana je metoda frekventne analize vibracija pri glodanju, kao metoda koja se često koristi u savremenim eksperimentalnim istraživanjima. Međutim, i matematičke i eksperimentalne metode analize vibracija pri glodanju imaju određena ograničenja. Polazeći od prethodnog, razvijena je inovativna metoda tangenti, bazirana na ranije korišćenoj metodi u okviru Laboratorije za mašine alatke Instituta za proizvodno mašinstvo FTN u Novom Sadu, i primeni savremenih mernih sistema. Pored toga, u ovom poglavlju je eksperimentalno potvrđen uticaj samopobudnih vibracija na kvalitet obrađene površine i geometrijsku tačnost obratka.<br />Metodologija sprezanja matematički i eksperimentalno definisanih funkcija frekventnog odziva elemenata mašine alatke prikazana je u sedmom poglavlju. Prezentovane su jednačine sprezanja pomerajnih odziva matematmički definisanih funkcija frekventnog odziva alata i držača alata, bazirane na Ojlerovoj teoriji grede, sa eksperimentalno definisanom funkcijom frekventnog odziva sklopa glavnog vretena mašine alatke.<br />U okviru osmog poglavlja razvijen je matematički model sila rezanja pri mikroglodanju. Predloženi model sila rezanja, koji uzima u obzir silu trenja između leđne površine alata i obrađene površine, implementiran je u unapređenu numeričku simulaciju glodanja čime je omogućena njena primena za definisanje graničnih dubina rezanja pri mikroglodanju.</p><p>Verifikacija razvijenih numeričkih i eksperimentalnih metoda za ispitivanje vibracija pri makroglodanju je prikazana u devetom poglavlju. Sproveden je niz eksperimentalnih ispitivanja, pri kojima su određivane granične dubine glodanja pri obradi tri različita materijala obratka (Al7075, 42CrMo4 i Ti-6Al-4V) na dva obradna sistema. Na osnovu ovih ispitivanjima izvršena je verifikacija unapređene numeričke simulacije glodanja i inovativne metode tangenti.<br />U desetom poglavlju prikazana je verifikacija metoda analize samopobudnih vibracija pri mikroglodanju. Primenom metodologije sprezanja pomerajnih odziva, definisani su modalni parametri obradnog sistema za mikroobradu, potrebni za definisanje graničnih dubina rezanja, tj. karte stabilnosti, unapređenom numeričkom simulacijom mikroglodanja. Karta stabilnosti definisana razvijenom unapređenom numeričkom simulacijom, verifikovana je eksperimentalno i poređenjem sa literaturnim izvorima.<br />U jedanaestom poglavlju data su zaključna razmatranja, kritički osvrt na ostvarene rezultate, i pravci budućih istraživanja.<br />Dvanaesto poglavlje prikazuje pregled korišćene literature, koju čini 218 referenci većim delom citirane u samom radu, a u zasebnom poglavlju dati su prilozi.</p> / <p>The subject of research presented in the doctoral dissertation are self-excited vibrations in milling. Based on a detailed analysis of the self-excited vibrations occurrence, a certain parallel has been established between macro and micromilling, for cases when the depth of cut is greater than the cutting edge radius of the tool. For such adopted assumptions, models of advanced numerical simulation of macro and micromilling processes were developed. The developed models were comprehensively verified, on the one hand, by comparison with the results of other authors, and on the other hand by comparison with own experimental results. An innovative tangent method has been proposed for the experimental definition of the cutting depth limit in milling, and the method of machined surface roughness has been proposed for micromilling, having in mind the available measuring equipment. Mathematical models and experimental methods were verified by machining three characteristic types of materials on two machining systems in macromilling, and one material on one machining system in micromilling. The results of the research are presented through twelve chapters, the content of which is listed below.</p><p>In the first, introductory chapter, the importance of the research of self - excited vibrations in macro and micromilling is pointed out. The topicality of the research is also presented by analyzing the number of scientific papers dealing with the issue of self - excited vibrations in the period of the last twenty - five years.<br />The second chapter presents in detail the previous research on self-excited vibrations during macromilling, while the third chapter presents research on self-excited vibrations during micromilling. An analysis of the influential parameters on the cutting depth limit was performed, which is a basic indicator of the dynamic stability of both macro and micromachining systems.<br />Based on the findings presented in the second and third chapters, the fourth chapter defines the goals and hypotheses of the research.<br />Mathematical methods for defining the stability lobe diagram of the machining system are presented in the fifth chapter. Two mathematical models for defining the stability lobe diagram for macromachining are presented, the model of the tool&rsquo;s mean contact angle and the model of Fourier series. Numerical simulation of the milling process is presented, intended primarily for the simulation of cutting forces. Starting from the previously presented idea, a new mathematical method for predicting the cutting depth limit has been developed within this chapter - an improved numerical simulation of the milling process.<br />In the sixth chapter, experimental methods of machine tools vibration identification are presented, ie experimental determination of machining systems modal parameters as well as methods of self - excited vibrations detection during milling. In order to define the cutting depth limit, the method of vibrations frequency analysis during milling is presented, as a method that is often used in modern experimental research. However, both mathematical and experimental methods of milling vibration analysis have certain limitations. Starting from the previous one, an innovative tangent method was developed, based on the previously developed method, used within the Laboratory for Machine Tools, Institute of Production Engineering Facultz of Technical Sciences in Novi Sad, and the application of modern measuring systems. In addition, in this chapter, the influence of self - excited vibrations on the machined surface quality and the geometric accuracy of the workpiece is experimentally confirmed.<br />The methodology of machine tool elements mathematically and experimentally defined frequency response functions coupling is presented in the seventh chapter. The displacement responses coupling equations of mathematically defined tools and tool holders FRF&#39;s (based on Euler &#39;s beam theory) with the experimentally defined FRF of the machine tool main spindle assembly are presented.<br />Within the eighth chapter, a mathematical model of cutting forces in micromilling was developed. The proposed cutting forces model, which takes into account the friction force between the reliefe tool surface and the machined surface, is implemented in an advanced numerical micromilling simulation, which enables its application to define cutting depth limit in micromilling.</p><p>Verification of the developed numerical and experimental methods for vibrations analysis during macromachining is presented in the ninth chapter. A series of experimental tests were performed, during which the cutting depth limits were determined during the milling of three different workpiece materials (Al7075, 42CrMo4 and Ti-6Al-4V) on two machining systems.<br />In the tenth chapter, the verification of the methods of analysis of self-excited vibrations during micromilling is presented. Using the methodology of coupling displacement responses, the modal parameters of the machining system for micromachining are defined, needed to define the cutting depth limits, ie. stability lobe diagram, by advanced numerical micromilling simulation The stability lobe diagram, defined by the developed advanced numerical simulation, was verified experimentally and by comparison with literature sources.<br />The eleventh chapter provides concluding remarks, a critical review of the achieved results, and directions for future research.<br />The twelfth chapter presents an overview of the used literature, which consists of 218 references, mostly cited in the paper itself.</p>

Hoy en día, las organizaciones industriales enfocados en la confección de prendas algodón buscan incrementar su competitividad a través de actividades que generen valor agregado a los productos. Por ello, el objetivo de este artículo es mejorar el proceso de cortado de tela de las mypes exportadoras de prendas de algodón mediante la identificación y eliminación de desperdicios, definidos como procesos o actividades que no agregan valor, específicamente en el área de corte de una empresa textil. Además, esta mejora se dará bajo la aplicación de la filosofía Lean Manufacturing a través de las herramientas del VSM, SMED y estandarización de trabajo, el cual se respalda mediante un análisis de datos, validación económica y simulación mediante el uso de los datos históricos de la empresa en estudio. Asimismo, a través del estudio realizado se logró reducir los reprocesos por defecto de 13.12% a 4.23%, los procesos con demora se han reducido de 18.49 a 9.61% y el índice de productividad del área de corte se incrementó de 0.38 a 1.16. / Today, industrial organizations focused on making cotton garments seek to increase their competitiveness through activities that generate added value to products. Therefore, the objective of this article is to improve the fabric cutting process of cotton garment exporting mypes by identifying and eliminating waste, defined as processes or activities that do not add value, specifically in the cutting area of ​​a textile business. In addition, this improvement will occur under the application of the Lean Manufacturing philosophy through the VSM, SMED and work standardization tools, which is supported by data analysis, economic validation and simulation through the use of historical data from the company under study. Likewise, through the study carried out, it was possible to reduce the default reprocesses from 13.12% to 4.23%, the processes with delay have been reduced from 18.49 to 9.61% and the productivity index of the cutting area increased from 0.38 to 1.16. / Trabajo de investigación