Dissertations / Theses on the topic 'Tube mill'

The PhD research project is to examine if it is possible to minimize the mill faults and fires in the Tube Ball mill operation by using a model based approach. The research outcome proves that the risks of mill fault can be monitored and alerted by implementing the model based on-line condition monitoring software that developed through the PhD project. Coal fired power stations nowadays regularly use coal with higher volatile contents and Biomass materials to satisfy the government regulations on sustainable and renewable energy. This greatly increases the risks of explosions or fires in milling plants. However, there are no acceptable measurement methods available at the present and it is difficult to identify if there will be a fire in the mill. Therefore, the project is carried out from the study mill mathematical model to mill condition monitoring. Monitoring the mill operation conditions only based on currently available on-site measurement without requiring any extra hardware is a cost effective solution and will pose a great challenge. A mathematical model of coal mills is developed using computational intelligent algorithms for prediction of potential mill faults.

Intresset för sömlösa stålrör med stora ytterdiametrar i förhållande till tunna väggtjocklekar har ökat tillsammans med att högre hållfasthet i olika stålsorter tillkommit. Detta gör det möjligt att tillverka lättare, billigare och mer materialeffektiva stålprodukter med samma eller högre hållfasthet som tidigare. Denna nya utvecklingsriktning medför förändringar och utmaningar i en av företaget Ovakos produktionslinor i Rörverk 5 Hofors, vilket de har behov av att samarbeta med maskinkonstruktionsföretaget BEKAB för att utvärdera och utveckla. I Ovakos produktionslina i Rörverk 5 finns en del av ett asselvalsverk som kallas för "förreducerare". Denna del av asselvalsverket ser Ovako ett stort intresse i att utvärdera och utveckla för att bättre anpassas till den nya utvecklingsriktningen.  En känd utmaning hos förreduceraren sen tidigare är att den från början är framtagen för att reducera ner ett kvalitetsproblem hos rörprodukterna som kallas för trattbildning. Projektet fördjupar sig därför inom trattbildning för att bättre förstå grunden till förreducerarens nuvarande design för att därefter genomföra en redesign av förreduceraren. I en nulägesanalys av nuvarande förreducerare framkommer ett flertal olika produktionsutrustningsproblem med tillhörande kvalitetsproblem hos rörprodukterna. Projektet väljer därmed att fokusera på de produktionsutrustningsproblem som ger störst effekt för förreduceraren om de löstes. Detta resulterar i ett nytt produktkoncept av förreduceraren i form av en visuell 3D-CAD-modell med tillhörande hållfasthetsberäkningar och materialoptimering. Studien behandlar ämnen som design, konstruktion, produktutveckling, hållfasthet samt materialoptimering.
The interest in seamless steel tubes with large outside diameters in relation to thin wall thickness has increased along with the strength improvements in various steel grades. This makes it possible to produce lighter, cheaper and more material-efficient steel products with the same or greater strength as before. These new development directions bring changes and challenges in one of the company Ovako's production lines in Tube Mill 5 Hofors, which they need to cooperate with the design agency BEKAB to evaluate and develop. In Ovako's production line in Tube Mill 5 there is a part of an assel mill called "förreducerare". Ovako sees a lot of interest in evaluating and developing this part of the assel mill in order to better adapt to the new development directions. A well-known challenge of the existing reduction equipment is that it was initially developed to reduce a quality issue with the tube products called funnel formation. The project therefore immerses itself into the funnel formation in order to better understand the foundations of the current design of the reduction equipment and to then implement a redesign of the reduction equipment. A situation analysis of the current reduction equipment reveals a number of different production issues with their accompanying quality issues in the tube products. The project thus chooses to focus on the production issues that would have the greatest impact on the reduction equipment if they were resolved. This results in a new product concept of the reduction equipment in the form of a visual 3D-CAD-model with associated strength calculations and material optimization. The study covers topics such as design, engineering, product development, material strength calculations and material optimization.

Revegetation is a reclamation method used to stabilize land that has been disturbed (i.e. Uranium contamination) by mining in an effort to establish a sustainable plant community. During 1986-88, large amounts of topsoil were removed at the site adjacent to the Tuba City disposal cell to remove windblown contaminated soil and construct the Uranium disposal cell. Re-establishing a sustainable plant community is critical to minimizing dust emissions, controlling erosion, and improving rangeland condition, and enhancing evapotranspiration. The objective of this study was to evaluate the long-term effectiveness of revegetation efforts by 1) comparing plant species composition and abundance on the reclaimed area and native rangeland protected from grazing, 2) current rangeland condition by comparing plant communities on grazed and protected native rangeland 3) differences in soil fertility, particle size distribution, and morphology that could be influencing vegetation differences in the three areas, 4) landscape-scale evapotranspiration rates and effects on groundwater recharge in the three plant communities, and 5) the value of using relatively undisturbed Legacy Management parcels as reference areas. Plant cover in the revegetated area was greater in 2014 (24%) than in 1998 (15%); however, plant species composition and diversity in the revegetated area and in the reference area remained markedly different. The effectiveness of revegetation is improving, but given the extended amount of time the improvement is not matching the protected area’s percent cover. The reference area showed highest cover during the early cool-season. However, the grazed area possessed the highest plant species composition and highest foliar cover in the late warm-season. The vegetation relevé estimate and foliar cover statistics show the revegetated area (24%) was significantly less than the surrounding vegetation (35%), even after 26 years since original revegetation. These results are critical in assisting Legacy Management to identify environmentally sustainable methods for the continuous management of this site and others in the area.

Le MILO (Magnetically Insulated Line Oscillator) est une source micro-onde de forte puissance capable de produire des puissances crêtes supérieures au gigawatt à des fréquences de quelques gigahertz. Ce tube hyperfréquence est un oscillateur à champs électrique et magnétique croisés qui ne requiert pas de structure externe pour produire le champ magnétique nécessaire au guidage du faisceau d'électrons. Ceux-ci sont produits par émission explosive à partir d'une cathode de type velours et sont accélérés par la différence de potentiel dans l'espace anode – cathode. L'anode constitue une cavité hyperfréquence capable d'emmagasiner de l'énergie électromagnétique, transférée depuis le faisceau d'électrons. Ainsi, la géométrie du tube fixe les conditions de propagation des électrons dans le vide (isolement magnétique) et les conditions de synchronisme permettant les échanges d'énergie dans la structure hyperfréquence. Cette thèse vise à détailler les caractéristiques de fonctionnement d'un MILO compact, c'est-à-dire à l'échelle ½ en comparaison des dispositifs existants, en vue d'un développement expérimental. Pour cela nous avons démontré la faisabilité d'un modèle réduit en redimensionnant tous les paramètres géométriques. Des simulations en géométrie 2D et 3D sous code PIC – Electromagnétique MAGIC ont permis de caractériser, d'une part, la structure hyperfréquence afin d'optimiser les couplages cavité – guide d'onde de sortie pour l'extraction du rayonnement et de démontrer, d'autre part, les contraintes physiques limitant la puissance micro-onde de sortie. Le prototype ainsi optimisé a conduit à la conception d'un dispositif expérimental où les tests préliminaires à froid (sans faisceau) ont montré une bonne concordance avec les prévisions théoriques. Cette thèse ouvre la voie à l'expérimentation et au développement d'une source micro-onde de puissance compacte.

A local community hospital in Montana expressed a desire to establish a written clinical guideline for transitioning preterm infants from enteral gavage feedings to oral feedings. This desire was prompted by a change in the method of quantifying breast milk intake of preterm infants when transitioning them from enteral gavage feedings to at-breast feedings in a Neonatal Intensive Care Unit (NICU). The hospital changed from the practice of test-weighing as a clinical indicator to quantify breast milk intake to the "Salt Lake City Feed Plan". Procedures: Retrospective data from four consecutive years were collected from quality assessment chart audit data provided to the author in aggregate form. Twenty-nine records met the selection criteria. A descriptive presentation of the aggregate data follows. Results: The average number of total deliveries per year was 1,151. The average percentage of preterm deliveries that occurred between 32 - 37 completed weeks of gestation was 16.3 percent. Of the twenty-nine records that met the selection criteria, 17 were male and 12 were female. The birth weight ranged from 1.75 kilograms (kg) to 2.31 kg. Weight at discharge ranged from 2.66 kg. to 2.99 kg., indicating a weight gain of 0.68 kg. to 0.91 kg. at discharge. Number of days with an indwelling nasogastric enteral feeding tube ranged from 1 to 23 days. Length of hospital stay ranged from 7 to 29 days. The length of stay for exclusively bottle fed preterm infants ranged from 13 to 27 days, whereas the breastfeeding preterm infants who utilized test -weighing or the "Salt Lake City Feed Plan" ranged from 7 to 29 days. Breast fed preterm infants in whom test-weighing or the "Salt Lake City Feed Plan" was utilized had 4 to 4.315 fewer days of hospitalization compared to preterm infants who were exclusively bottle-fed. Conclusion: The literature review and the aggregate data collected by the rural community hospital provide baseline information to create, implement and support an evidence-based clinical guideline to transition preterm infants from enteral gavage feedings to oral feeding.

This thesis is the first stage of a project to investigate the parameters effecting the performance of tube mills. The main topics that the project will cover are the motion of mill charge and the wear characteristics of the balls and the mill liners. A literature survey highlighted that no examination had been performed that investigated the motion of a particle with specific emphasis on the response to changes in the coefficient of friction between the particle and the liner. This thesis concentrates on the motion of a single particle moving on the inside of a smooth rotating cylinder. Three formulations are presented that model the motion of the particle. The first model assumes that the particle slides along the cylinder. To ensure that it slides, and does not roll, a block shaped particle is modelled. The second motion type assumes that a spherical shaped particle rolls along the cylinder. The assumption that is made, is that the point of contact between the ball and the cylinder does not slip or skid. This mode of rolling has been defined as Pure Rolling. A third model is proposed that is a combination of the sliding and rolling models. The formulation attempts to incorporate both actions, rolling and sliding. In this way the motion of the particle.is dependent on both the rolling and sliding interactions. The governing equations for the Sliding and Rolling models are solved numerically, using an Euler Forward Approximation. Both models are solved by a computer implementation of the resulting numerical equations. The Sliding program has been extended to animate the response of the block on the inside of the cylinder. The theoretical predictions from the two numerical solutions are presented and discussed.

Includes bibliographical references.
This thesis is the second stage of a project to investigate the parameters affecting the performance of tube mills. The main topics that the project will cover are the motion of the mill charge and the wear characteristics of the mill charge and mill liners. Nates, in his thesis, performed a literature survey that highlighted the need for an investigation into the motion of a particle with emphasis on the response to changes in the coefficient of friction between the particle and the liner. Nates developed theoretical models for a particle moving on the inside of a rotating liner. The models developed were for a block and sphere moving on a flat liner. Although a better understanding of the motion of a particle was achieved, the models did not take all the variables into account. One of the assumptions made by Nates was that the particle was moving on a flat liner. This thesis concentrates on the motion of a particle on a corrugated liner in a rotating cylinder. Two formulations are presented that model the motion of a particle. The first model assumes that the particle being modelled is a block. The modelling of the particle as a block ensures that the particle does not roll. There are two possibilities as to the type of motion which the block can experience. The first possibility is where the block moves at the same velocity as the - rotating liner whilst the second possibility is where the block can slide relative to the rotating liner. Three different liner configurations were used in the investigation of the motion of a block. The second model assumes that the particle can move with pure rolling as well as with a combination of rolling and sliding. For pure rolling it is assumed that at the point of contact between the sphere and liner that there is no skidding or sliding. The governing equations for the model of a block on a corrugated liner are solved numerically using a Fourth-Order Runge-Kutta Method. The theoretical predictions of the motion of a block on a corrugated liner are presented - and discussed. The model for a sphere on a corrugated liner was derived but no attempt was made to solve it numerically. It is envisaged that the numerical solution of the model for a sphere will be included in the next stage of the project. An experimental investigation was done to validate the theoretical model for a block on a corrugated liner. Only two of the three liners used in the numerical investigation were tested. There was good correlation between the experimental results and the theoretical predictions. All the experimental results are presented and comparisons made between the theoretical predictions and the experimental results. The thesis is concluded with a discussion of trends and observations made during the investigation into the motion of a block on a corrugated liner, and it is shown that the model for a block on a corrugated liner does satisfactorily predict the response of the block to varying initial conditions. Suggestions are also made as to possible ways to improve and expand on the current models used to describe the motion of a mill charge.

Att kartlägga hur ett företags olika processer ser ut är en viktig del ur ett kontinuerligtförbättringsarbete. Uppdraget för denna studie består av att kartlägga dagliga mjölkrundor påen del av fabriken, som därmed skall bidra till att eventuella problem synliggörs. Studienbehandlar logistik och materialhantering med fokus på transport och ergonomiska arbetsplatsersom bör följa riktlinjer för Lean. Att följa de olika ergonomiska riktlinjerna på ett framgångsriktsätt kan skapa goda förutsättningar som därmed kan gynna ekonomin. Utgångspunkten har varitatt med hjälp av intervjuer samt observationer skapa en god förståelse för hur de nuvarandemjölkrundorna ser ut, då det i nuläget inte finns något standardiserat arbetssätt på det studeradeområdet basmodulen.I studien presenteras de faktorer i produktionen som har en påverkan på ergonomin samt defaktorer som bidrar till förbättringsmöjligheter. Resultatet av studien baseras på litteraturstudieroch de tre intervjuer som genomförts med berörda truckförare. En jämförelse gjordes mellanLean och Volvos egna Leanarbete, Volvo Production System där vikten belystes i detstandardiserade arbetssättet och att företaget standardiserar de olika arbetsmomenten för attlättare kunna implementera förbättringsförslagen. Studien avslutas med att utforma förslag påhur mjölkrundorna bör se ut för att möjliggöra besparingar inom effektivitetssynvinkeln samtövriga förbättringsförslag som skall gynna företaget i helhet. Författarnas slutsats avexamensarbetet är att det finns goda möjligheter och förutsättningar för att positivt införastandardiserade körrundor för basmodulen som därmed underlättar implementering avresterande förbättringsförslag.
To identify how a company's different processes look is an important part of continuousimprovement work. The assignment for this study consists of mapping the daily in-plant milkrunsin one part of the factory, with the goal to make any problems visible. The study deals withlogistics and materials management with a focus on transport and ergonomic aspects that shouldbe in line with Lean thinking. The starting point in this study has been information frominterviews and observations, to provide a good understanding for the in-plant milk-runs. Thestudy includes a brief literature review, onsite observations as well as three in-depth interviews.A comparison was made between the strategy Lean and Volvo's own interpretation of Lean, theVolvo Production System, where the emphasis was highlighted in the standardized approachand that the company standardizes the different workflows to facilitate implementation of theimprovement proposals. The study concludes by formulating proposals on how milk-runsshould look to enable savings in the efficiency perspective and other improvement proposalsthat will benefit the whole company. The author’s conclusion of the thesis work is that there aregood opportunities to positively introduce standardized milk runs for the studied area calledbasmodulen, which will help the company when implementing the improvements.

Examen de l'action de la temperature, de la lummiere et de traitements par la gibberelline sur la germination des graines de cyclamen. Developpement de la plantule et formation du tubercule au niveau de l'hypocotyle. Etude biochimique de l'utilisation des reserves et de la synthese d'amidon et de glucofructosanes dans le tubercule

Diploma thesis "Gender and manpower in production companies in the Chomutov region" is focused on historically and sociologically oriented research of employment of men and women in production companies in the Chomutov region over last 50 and 70 years respectively. The main aspects which are included in the theoretical part of this work are gender relations in the production companies, that is the history of the employment of women, horizontal and vertical gender segregation including wages and salaries and employee education. The analyzed data are from the period of mid 20th century and the beginning of the 21st century and focus primarily on the production companies of The Tube and Iron Rolling Mill and their current successor Sandvik. By means of data analysis, the methodical part of the thesis describes differences and changes which have ocurred in the horizon of last 50 and 70 years in the manpower employment in production companies with respect to gender. KEYWORDS Gender, Feminism, Manpower, Socialism, The Tube and Iron Rolling Mill, Production, Chomutov

碩士
高苑科技大學
機械與自動化工程研究所
97
This study is aimed at the static axial compression and dynamic axial impact tests to probe into the buckling behavior of mild steel circular tubes. All the tubes suffer, statically or dynamically, pure compression before buckling. And the buckling mechanism is either local crushing or global buckling. The number of crushing wrinkle increases as the striking energy increasing. The deformation mechanism is affected by the slenderness ratio as well. When the slenderness ratio is greater than about 13, the tube suffers global buckling regardless of static compression or dynamic impact, and the buckle takes place in the plastic region. With the same impact energy, The Location of initial crushing at alters with the axial length of the tube, While the total axial displacement is not affected by the axial length of a tube. A groove (imperfect) effectively affects the buckling behavior of a circular tube. When the minimum interval between the groove and one end of the tube is greater than a critical value, the tube suffers local crushing as well as global buckling at the groove. In order to get insight into the buckling mechanism of a circular tube, the crystal grain is inspected by melallographic test. The bending area of local crushing or global buckling apparently suffers serious grain deformation, while the grains in the other region almost not deform. It is revealed obviously that the stress distribution is much nonuniform when a tube is at the moment of buckling.

碩士
輔仁大學
化學系
106
Part.Ⅰ Polymer monolith microextraction (PMME) based on capillary monolithic column is an effective and useful technique to preconcentrate trace analytes from environmental and biological samples. A wide variety of household, medical systems and industrial waste waters have been discharged into groundwater, rivers and oceans without sewage treatment. Many organic compounds that have adverse effects on the human body have been detected such as non-steroidal anti-inflammatory drugs and endocrine disrupting compounds are collectively called environmental pollutant. The sample preparation methods was developed with environmental pollutant, including Naproxen (Na), 2,4-diclorophenol (2,4-DCP), Diclofenac (Di), Estradiol (E2), Ibuprofen (Ibu), Phenothiazine (Ptz), and Mefenamic acid (Me) by UPLC-DAD ( Ultra performance liquid chromatography- Diode array detection，UPLC-DAD). The PMME optimal parameters, silanized with MSMA about 5 hr, polymerized about 1 hr, loading speed for the PMME was 0.9 mL/hr and the elute solvent was 200 μL 25 mM ammonium acetate pH 5.0: MeOH (4:6,v/v). The coefficients of correlation (r2) for the UPLC-DAD calibration curves were greater than 0.9997. The limits of detection (LOD) and limits of quantificantion LOQ) were determined within 0.20 to 2.12 ng/mL and 0.68 to 7.07 ng/mL. The recovery of environmental pollutant in spike urine were 40.0 % to 102.0 %. Though the recovery was't very well, it could effectively reduce the matrix effect. These results shown this capillary monolithic column could be used for extraction environmental pollutant from human urine sample or reduce the matrix effect such as sorbent. Part.Ⅱ Acetaminophen (AC), is a medicine used to treat pain and fever. It is typically used for mild to moderate pain relief. However, long-term exposure or excessive use of acetaminophen causes accumulation of toxic metabolites, which leads to kidney and liver disease thus precise determination and quantitation is important. Development of highly sensitive and selective electrochemical sensors using chitosan (CHS) and metal-organic frameworks (MOFs) modified glassy carbon electrode (GCE) is creating fast and simple method for determination of acetaminophen in environmental water Development of highly sensitive and selective electrochemical sensors using chitosan (CHS) and metal-organic frameworks (MOFs) modified glassy carbon electrode (GCE) is creating fast and simple method for determination of acetaminophen in environmental water . In this optimal conditions, the results shown the modified GCE have properties of excellent electron transfer characteristics, low electron transfer resistance and increase the oxidation current by differential pulse voltammetry (DPV) and electrochemical impedance analysis (EIS). In the other hand the bare electrode and modified electrode were characterized by scanning electron microscope (SEM), energy dispersive spectrometer (EDS) and powder X - ray diffraction (PXRD), which confirmed that chitosan/ metal-organic frameworks modified electrode can be successfully prepared . The chitosan/metal-organic frameworks modified electrode shown a linear response for acetaminophen in the concentration range of 0.1 to 50 μM with detection limit of 30 nM at S/N = 3, respectively. In addition, the reproducibility and stability of this chitosan/ metal-organic frameworks modified electrode were discussed. Its relative standard deviation (RSD) of intra day and inter day were less than 4.74 % and 3.12 %, respectively. Stability still remanined above 100.84 % during one week. These results have confirmed that this modified electrode have satisfactory reproducbility and stability. Finally, this chitosan/ metal-organic frameworks modified electrode was successfully applied in the determination of acetaminophen in environmental water. The recovery was between 98.47 to 112.66 %. These results have confirmed that this modified electrode have good accuracy.