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Avguštin Janja - One of the best experts on this subject based on the ideXlab platform.
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Inquiry-based activr learing of preschool children using wood and metals.
2020Co-Authors: Avguštin JanjaAbstract:In the thesis, we want to present active learning and also an example of a project activity where children are actively involved in the crafts and technology activities that we have performed in the kindergarten. The purpose of the thesis is to present active learning in the preschool period as we have noticed that in the kindergartens, children rarely actively participate in activities and come to the final solutions and information on their own. We also wanted to determine which materials preschool teachers most commonly use in their work with children. This is why we focused on the most and the least commonly used material by preschool teachers. The results were obtained through a survey questionnaire which was distributed in the Miškolin kindergarten and via an online survey questionnaire. The results showed that preschool teachers most often use natural materials like wood and least often metal. This is why we focused on wood and metal material in the thesis. In the first part of the theoretical part, we present learning in the preschool period and focus on active learning where we present its importance, forms, principles and the role of preschool teachers in active learning. In the second part of the theoretical part, we focus on crafts and technology in the preschool period, curricular objectives for crafts and technology and the characteristics and properties of wood and metal. We also present the tools, devices and procedures that children have encountered during the practical part of the thesis by shaping wood and metal. In the kindergarten, we also performed a month-long project with children, in which children were actively involved and got to know wood and metal. Children actively participated in guided and free activities and actively acquired knowledge by exploring materials and finally made a final product (gift/toy) out of the material being discussed. During the activities, children learned about the properties of each material (they compared them and were able to find them in their immediate surroundings) and some of the basic techniques of wood and metal processing (grinding wood, tucking nails in wood with a hand hammer, pinching Wire, Running Wire around the nails, manual Wire design, bonding of wood and wood coating). As already stated, the results that we gathered from an online survey questionnaire show that preschool teachers most often use materials like wood and least often metal. At the same time, we established that 95% of respondents encourage active learning in kindergarten. Children typically learn about properties of materials at activities that are planned for 30-45 minutes, individually or in smaller groups along with practical work and various play improvisations. Kindergarten teachers most often evaluate the process of their activities by comparing products before and after planned activity with children, that way children find the activity more meaningful. With this thesis, we want to encourage preschool teachers to include different materials in their work with children in kindergarten
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Inquiry-based activr learing of preschool children using wood and metals.
2020Co-Authors: Avguštin JanjaAbstract:V diplomskem delu želimo predstaviti aktivno učenje v vrtcu in predstaviti primer projektne dejavnosti s področja tehnike in tehnologije, ki smo jo izvedli v vrtcu in v katero so otroci aktivno vključeni. Namen diplomskega dela je predstaviti aktivno učenje v predšolskem obdobju, saj opažamo, da je v vrtcih premalokrat vključen način dela, kjer otroci aktivno sodelujejo pri dejavnostih in samostojno pridejo do končnih rešitev in informacij. Z diplomskim delom smo želeli ugotoviti tudi, po katerih materialih strokovni delavci pri svojem delu največkrat posegajo. Zato smo se v diplomskem delu osredotočili na material, ki ga strokovni delavci pri svojem delu uporabljajo največkrat, ter na material, ki ga strokovni delavci pri svojem delu uporabljajo najmanjkrat. Rezultate smo pridobili s pomočjo anketnega vprašalnika, ki smo ga razdelili v fizični obliki v vrtcu Miškolin in prek spletnega anketnega vprašalnika (portal MojaAnketa). Rezultati so pokazali, da strokovni delavci največkrat posegajo po naravnih materialih, in sicer po lesu, najmanjkrat pa posegajo po kovinah. Zato smo se v diplomskem delu osredotočili na materiala les in kovino. V prvem delu teoretičnega dela smo predstavili učenje v predšolskem obdobju in se osredotočili na aktivno učenje, pri katerem smo predstavili njegov pomen, oblike, načela in vlogo vzgojitelja pri aktivnem učenju. V drugem delu teoretičnega dela smo se osredotočili na tehniko v predšolskem obdobju. Predstavili smo pomen tehnike v predšolskem obdobju, kurikularne cilje s področja tehnike in tehnologije ter značilnost materialov les in kovina. Predstavili smo tudi orodja, pripomočke in postopke, ki so jih otroci spoznali pri praktičnem delu diplomskega dela, in sicer pri oblikovanju lesa in kovine. V vrtcu smo z otroki izvedi tudi večtedenski projekt, pri katerem so na aktiven način spoznavali les in kovino. Otroci so skozi vodene in proste dejavnosti aktivno sodelovali pri spoznavanju in raziskovanju materiala, na koncu pa iz spoznanega materiala izdelali končni izdelek (darilo/igračo). Tekom dejavnosti so otroci spoznali lastnosti posameznega materiala (ju med seboj primerjali in znali poiskati v svoji okolici) ter se seznanili z nekaterimi osnovnimi postopki oblikovanja lesa in kovin (brušenje lesa, zabijanje žičnikov v les z ročnim kladivom, preščip žice, vodenje žice okoli žičnikov, ročno oblikovanje žice, lepljenje ter lakiranje lesa). Kot je že navedeno, smo prek anketnega vprašalnika ugotovili, da strokovni delavci največkrat posegajo po materialu les, najmanjkrat pa posegajo po materialu kovina. Obenem smo ugotovili tudi, da kar 95 % anketirancev spodbuja aktivno učenje v vrtcu. Otroci največkrat spoznavajo lastnosti materialov, pri aktivnostih, zasnovanih za 30–45 minut, individualno ali v manjših skupinah ob praktičnem delu in raznih igralnih improvizacijah. Napredek dejavnosti vzgojitelji najpogosteje ocenijo s primerjanjem izdelkov pred in po dejavnosti skupaj z otroki, da le-ti lažje osmislijo svoje delo. Z napisanim diplomskim delom želimo spodbuditi vzgojitelje, da bodo pri svojem delu v vrtcu skušali posegati po čim bolj raznolikih materialih in jih vključevali v svoje delo.In the thesis, we want to present active learning and also an example of a project activity where children are actively involved in the crafts and technology activities that we have performed in the kindergarten. The purpose of the thesis is to present active learning in the preschool period as we have noticed that in the kindergartens, children rarely actively participate in activities and come to the final solutions and information on their own. We also wanted to determine which materials preschool teachers most commonly use in their work with children. This is why we focused on the most and the least commonly used material by preschool teachers. The results were obtained through a survey questionnaire which was distributed in the Miškolin kindergarten and via an online survey questionnaire. The results showed that preschool teachers most often use natural materials like wood and least often metal. This is why we focused on wood and metal material in the thesis. In the first part of the theoretical part, we present learning in the preschool period and focus on active learning where we present its importance, forms, principles and the role of preschool teachers in active learning. In the second part of the theoretical part, we focus on crafts and technology in the preschool period, curricular objectives for crafts and technology and the characteristics and properties of wood and metal. We also present the tools, devices and procedures that children have encountered during the practical part of the thesis by shaping wood and metal. In the kindergarten, we also performed a month-long project with children, in which children were actively involved and got to know wood and metal. Children actively participated in guided and free activities and actively acquired knowledge by exploring materials and finally made a final product (gift/toy) out of the material being discussed. During the activities, children learned about the properties of each material (they compared them and were able to find them in their immediate surroundings) and some of the basic techniques of wood and metal processing (grinding wood, tucking nails in wood with a hand hammer, pinching Wire, Running Wire around the nails, manual Wire design, bonding of wood and wood coating). As already stated, the results that we gathered from an online survey questionnaire show that preschool teachers most often use materials like wood and least often metal. At the same time, we established that 95% of respondents encourage active learning in kindergarten. Children typically learn about properties of materials at activities that are planned for 30-45 minutes, individually or in smaller groups along with practical work and various play improvisations. Kindergarten teachers most often evaluate the process of their activities by comparing products before and after planned activity with children, that way children find the activity more meaningful. With this thesis, we want to encourage preschool teachers to include different materials in their work with children in kindergarten
Masanori Kunieda - One of the best experts on this subject based on the ideXlab platform.
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research of micro edm ecm method in same electrolyte with Running Wire tool electrode
Precision Engineering-journal of The International Societies for Precision Engineering and Nanotechnology, 2021Co-Authors: Wei Han, Masanori KuniedaAbstract:Abstract A micro rod machining method which can switch between electrical discharge machining (EDM) and electrochemical machining (ECM) by attaching/detaching a diode to/from a bipolar pulse generator in parallel to the working gap was newly developed using a Wire electrode made of tungsten. The problem of the Wire electrode wear was eliminated by the use of the Wire electrochemical turning (WECT) method in which the tungsten Wire electrode is continuously Running. The ultra-short bipolar pulse current was generated by the electrostatic induction feeding method where a pulse voltage is coupled to the working gap through a feeding capacitance. The machining characteristics of three types of Wire guide; disk-shaped WC guide, laminated Wire guide and cylindrical acrylic guide, were studied. The experimental results showed that the cylindrical acrylic guide has the best machining characteristics without the influence of guide wear and with less stray current flowing through the working gap. Using the cylindrical acrylic guide, the influences of the feeding capacitance C1, and the total amplitude of the pulse voltage on the machining characteristics were studied. Finally, a stainless steel SUS 304 micro-rod with a high aspect ratio of 14 was fabricated efficiently by using the EDM and ECM modes for rough and finish machining in sequence with the same setup, pulse generator, and neutral electrolyte.
Wei Han - One of the best experts on this subject based on the ideXlab platform.
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research of micro edm ecm method in same electrolyte with Running Wire tool electrode
Precision Engineering-journal of The International Societies for Precision Engineering and Nanotechnology, 2021Co-Authors: Wei Han, Masanori KuniedaAbstract:Abstract A micro rod machining method which can switch between electrical discharge machining (EDM) and electrochemical machining (ECM) by attaching/detaching a diode to/from a bipolar pulse generator in parallel to the working gap was newly developed using a Wire electrode made of tungsten. The problem of the Wire electrode wear was eliminated by the use of the Wire electrochemical turning (WECT) method in which the tungsten Wire electrode is continuously Running. The ultra-short bipolar pulse current was generated by the electrostatic induction feeding method where a pulse voltage is coupled to the working gap through a feeding capacitance. The machining characteristics of three types of Wire guide; disk-shaped WC guide, laminated Wire guide and cylindrical acrylic guide, were studied. The experimental results showed that the cylindrical acrylic guide has the best machining characteristics without the influence of guide wear and with less stray current flowing through the working gap. Using the cylindrical acrylic guide, the influences of the feeding capacitance C1, and the total amplitude of the pulse voltage on the machining characteristics were studied. Finally, a stainless steel SUS 304 micro-rod with a high aspect ratio of 14 was fabricated efficiently by using the EDM and ECM modes for rough and finish machining in sequence with the same setup, pulse generator, and neutral electrolyte.
Webe Tobias - One of the best experts on this subject based on the ideXlab platform.
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Contribution to the study of the lifetime behavior of Wire ropes under a combined tensile, bending and torsion load
2013Co-Authors: Webe TobiasAbstract:Seile, die über Scheiben laufen erfahren zusätzlich zur Beanspruchung auf Zug eine Biegebelastung. Laufende Seile können auch ohne die Möglichkeit zur freien Drehung der Seilenden einen verdrehten Zustand aufweisen, was den oben genannten Belastungszustand um die Torsionsbeanspruchung erweitert. Aufgrund der bisher bestehenden Unkenntnis bezüglich des Einflusses von Verdrehungen auf die ertragbare Biegewechselzahl bzw. die Seillebensdauer, wird im Rahmen der vorliegenden Arbeit dieser Belastungszustand mit dem Ziel einer rechnerischen Bestimmung untersucht. Kapitel 1 führt in die Thematik ein und beschreibt Ursachen, die zu einer Seilverdrehung führen können. In Kapitel 2 wird eine Übersicht über den Stand der Forschung bei laufenden Seilen gegeben und auf die bisherigen Erkenntnisse ausgewählter Ursachen der Seilverdrehung eingegangen. Die bestehende Beschreibung dieser Ursachen, die zu einer Seilverdrehung führen, werden in Kapitel 3 auf theoretische Weise behandelt. Des Weiteren werden die Grundlagen und die Begrifflichkeiten von Drehung und Verdrehung beschrieben sowie die geometrischen Veränderungen innerhalb des Seils in Abhängigkeit der Verdrehung betrachtet. Da die vorliegende Arbeit u. a. zum Ziel hat, den Einfluss diskreter Verdrehungen auf die Lebensdauer laufender Drahtseile rechnerisch abzubilden und dies, wie oben bereits dargelegt, nur durch Versuche möglich ist, wurden im Rahmen dieses Forschungsprojektes systematische Versuchsreihen mit gezielter Variation der Untersuchungsparameter gefahren. In Kapitel 4 werden die Versuchsgrundlagen der durchgeführten Versuche beschrieben sowie die verwendeten Versuchsseile mit ihren Eigenschaften dargestellt. Die im Rahmen dieses Forschungsprojektes durchgeführten experimentellen Untersuchungen mittels Dauerbiegeversuchen und die daraus resultierenden Ergebnisse werden in Kapitel 5 dargestellt. Zudem wird an dieser Stelle die vorgenommene Regressionsanalyse der Versuchsergebnisse beschrieben und die daraus ermittelte Berechnungsformel zur Bestimmung der ertragbaren Bruchbiegewechselzahl laufender Drahtseile unter dem Einfluss diskreter Verdrehungen abgebildet. Die experimentellen und theoretischen Untersuchungen zeigen, dass der Einfluss der Verdrehung neben der Seilkonstruktion und des Verdrehgrades abhängig von der Seilzugkraft und des D/d-Verhältnisses ist. Des Weiteren zeigen die Ergebnisse dieser Arbeit, dass der Einfluss der Verdrehung in Abhängigkeit der Seilkonstruktion nicht zwangsläufig zu einer Reduzierung der Lebensdauer führt. Je nach Parameterwahl, Seilkonstruktion und Verdrehgrad ergeben sich auf Basis der systematisch durchgeführten Versuchsreihen rechnerische Lebensdauersteigerungen von bis zu 25% im Bezug zur Seillebensdauer im unverdrehten Zustand (vgl. Kapitel 5.3). Außerhalb der diskreten Verdrehwinkelbereiche in denen eine Lebensdauersteigerung auftritt, sinkt die Lebensdauer infolge der Seilverdrehung stellenweise stark ab. Besonders gravierend ist der Einfluss von Verdrehung auf die Seillebensdauer des untersuchten mehrlagigen Spiralrundlitzenseils. Durch die gegenläufige Verseilung der Litzenlagen wirkt sich die in Kapitel 3.5 dargestellte Lastumverteilung stärker aus als bei einlagigen Rundlitzenseilen. Die rechnerisch bestimmte Lebensdauerreduzierung im Bezug zur Seillebensdauer im unverdrehten Zustand liegt bei einem im Verhältnis zu den untersuchten Verdrehwinkeln der einlagigen Rundlitzenseile relativ geringen Verdrehwinkel von omega = 180°/100d und entsprechender Parameterwahl bereits bei -77% (siehe Kapitel 5.3). Durch die in dieser Arbeit auf Basis von systematischen Versuchsreihen ermittelte Berechnungsformel ist es erstmals möglich, den Einfluss diskreter Verdrehungen auf die Lebensdauer laufender Drahtseile zu bestimmen. Die vorgenommene Anpassung an die international anerkannte Gleichung zur Berechnung der Lebensdauer laufender Drahtseile nach Feyrer (vgl. Seite 43 u. Seite 110), ermöglicht eine grundlegende und weltweite Anwendung der hier aufgestellten Berechnungsmethode zur Berücksichtigung diskreter Verdrehwinkel (vgl. [Feyrer2007] u. [Feyrer2011]). Mit den theoretischen und experimentellen Betrachtungen zur Seilverdrehung lassen sich sowohl bei der Auslegung eines Seiltriebes als auch im Betrieb, die Seile auf eine mögliche Verdrehung hin untersuchen und der daraus resultierende Einfluss auf die Lebensdauer bestimmen. Die vorliegenden Untersuchungen sind daher für die Sicherheit in der Anwendung und für eine technische bzw. ökonomische Optimierung relevant.The lifetime of Running ropes is affected mainly by the load (tensile load and bending) and influencing factors related to the rope itself and to the rope drive (e.g. [Feyrer2007]). Decades of research in the field of Wire ropes have produced detailed knowledge on different influencing factors on the rope lifetime (e.g. [Mueller1965], [Wolf1987], [Schoenherr2005] and [Feyrer2007]). Many of these influencing factors can be considered in Feyrer’s lifetime prediction formula for Running Wire ropes [Feyrer2011]. Up to now, the uptwisted or untwisted state of a Wire rope could not be considered in the lifetime prediction of Running ropes. The up or untwisting of Wire ropes have various causes. Due to intensive research in this field, the reasons for rope twisting are well known and its occurrence has been described in detail (e.g. [Engel1958], [Rebel1997], [Chaplin2000], [Verreet2001], [Oplatka2004] u. [Feyrer2007]). According to the named references, the main causes of rope twist are height-stress, side deflection, torsional interactions and mounting/installation. Whereas twist caused by the mounting of the rope depends heavily on the accuracy of the manual work (not including height-stress or torsional interactions during installation), twist caused by the first three named points depends on the rope itself and its application. Due to the structure of round stranded Wire ropes, an axial load provokes a torque around the rope axis. The torque gradient depending on the axial load differs by rope construction (e.g. [Feyrer2007]). A connection in a series of components with different torque characteristics will show rotation under load, which is called torsional interaction ([Chaplin2000] and [Hobbs2013]). Side deflection describes the motion of a rope onto or off of a sheave in an angular direction. The fleet angle is given between each axis of symmetry of the rope and the sheave. In many cases, for example in reeving systems, side deflection of the rope is necessary because of design characteristics (e.g. [Weber2013]). If a Wire rope runs on a sheave under a certain fleet angle, it will first make contact with the sheave flange. From there it will move to the bottom of the groove in a combined movement of sliding and revolving [Schoenherr2005]. The revolving motion causes a rotation and therewith twisting of the Running rope. In rope drives with large differences in height, like hoisting plants, the first named reason of rope twist occurs (e.g. [Rebel1997], [Chaplin2000] and [Feyrer2007]). At the lower level of the mine shaft, only the payload of the conveyor appears as a tensile load on the rope. At the top of the system, a higher tensile force occurs by the additional rope weight itself, which must be considered. Under the circumstance of two rotation-resistant ends, a homogeneous torque occurs, resulting in the rope twisting differently along its length. In the upper area, the rope untwists while in the lower area the rope uptwists. The reason given for rope twist is called height-stress [Feyrer2007]. In its twisted state, a movement such as lifting causes a combined load on the rope while Running over a sheave. In addition to the tensile load and the bending of the rope, a torsional load exists. The focus of existing investigations in the field of combined loading (tensile load, bending and twist), has thus far been placed on free spinning rope ends ([Dreher1933], [Thieme1937] u. [Mannitz1958]). Furthermore a lifetime prediction under a certain rope twist is not available. As shown above, it is known that combined tensile, bending and torque loads occur, but these causes’ influences on rope life have not yet been thoroughly investigated. This makes a systematic investigation necessary. The present work shows the causes of rope twist in detail and describes the tests on bending machines which have been made during the corresponding research project (funded by the German Research Foundation DFG). Furthermore the investigation of Wire breaks as a discard criterion, microscopic analyse and the influence of twist on the lay length [Herrmann2011] are part of this research project. With a regression analysis of the bending test results, a mathematical equation is determined which can be integrated into Feyrer’s internationally renowned lifetime prediction formula. As a result of the systematic bending tests with and without twisting the rope, the influence of a constant twist of the rope in both directions, untwisted and uptwisted, is worked out for certain rope constructions. With the test results and a regression analysis, a polynomial was found by the author, which allows consideration of twist in lifetime prediction. The constants for the investigated rope constructions are given in table 5.4 on page 111. The determined equation enables the consideration of the influence of rope twist with good precision for the first time
