Deformation and annealing texture in the cold rolled low carbon steels is important for sheet metal forming operations and service performance. The aim of this study is to non-destructively investigate the effect of texture on magnetic anisotropy. Various samples having different textures and residual stress states, due to different % reduction in thickness, annealing and stress relieving treatment, were prepared. Texture maps were obtained by Magnetic Barkhausen noise measurements performed with 100 steps between the ranges of 00-3600 on the surface. Microstructure investigation by optical &amp / scanning electron microscopy / hardness and tension tests were performed / and texture was determined by X-Ray diffraction method. The results were compared, evaluated and discussed to establish relationship between texture and magnetic Barkhausen Noise emission.

The focus of this paper is to evaluate if forecast produced by the Central Bank of Sweden (Riksbanken) for the 12 month change in the consumer price index is unbiased? Results shows that for shorter horizons (h < 12) the mean forecast error is unbiased but for longer horizons its negatively biased when inference is done by Maximum entropy bootstrap technique. Can the unbiasedness be improved by strict ap- pliance to econometric methodology? Forecasting with a linear univariate model (seasonal ARIMA) and a multivariate model Vector Error Correction model (VECM) shows that when controlling for the presence of structural breaks VECM outperforms both prediction produced Riksbanken and ARIMA. However Riksbanken had the best precision in their forecast, estimated as MSFE

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As air traffic congestion grows, air traffic flow management (ATFM) is becoming a great concern. ATFM deals with air traffic and the efficient utilization of the airport and airspace. Air traffic efficiency is heavily influenced by unanticipated factors, or uncertainties, which can come from several sources such as mechanical breakdown; however, weather is the main unavoidable cause of uncertainty. Because weather is unpredictable, it poses a critical challenge for ATFM in current airport and airspace operations. Convective weather results in congestion at airports as well as in airspace sectors. During times of congestion, the decision as how and when to send aircraft toward an airspace sector in the presence of weather is difficult. To approach this problem, we first propose a two-stage stochastic integer program by emphasizing a given single sector. By considering ground delay, cancellation, and cruise speed for each flight on the ground in the first stage, as well as air holding and diversion recourse actions for each flight in the air in the second stage, our model determines how aircraft are sent toward a sector under the uncertainty of weather. However, due to the large number of weather scenarios, the model is intractable in practice. To overcome the intractability, we suggest a rolling horizon method to solve the problem to near optimal. Lagrangian relaxation and subgradient method are used to justify the rolling horizon method. Since the rolling horizon method can be solved in real time, we can apply it to actual aircraft schedules to reduce the costs incurred on the ground as well as in airspace. We then extend our two-stage model to a multistage stochastic program, which increases the number of possible weather realizations and results a more efficient schedule in terms of costs. The rolling horizon method as well as Lagrangian relaxation and subgradient method are applied to this multistage model. An overall comparison among the previously described methodologies are presented.

A thin polymer bilayer film was transformed into micro- and nano-tubes using strain driven self-rolling phenomena of polystyrene (PS)/poly (4-vinyl pyridine) (P4VP) film. Polymer bilayer was produced by consecutive deposition of PS and P4VP, from toluene and chloroform solutions, respectively, by dip-coating technique. The object formation proceeds from a opening in the film made by photolithography or by mechanical scratching followed by immersion of patterned sample in dodecylbenzene sulfonic acid (DBSA) solution. DBSA forms supramolecular complexes with pyridine rings of P4VP and increases the specific volume of the polymer. Since the solution is neutral to PS layer, bilayer film develops strain due to unequal swelling of polymers in solution of DBSA and hence the film bends and scrolls in order to minimize its free energy and form tubes. The length of the tubes and the direction of rolling are determined by mechanical patterning of the film. UV-photolithography is used to fabricate patterns of polymer bilayer in order to create tube in a precise manner. The kinetics of the tube formation was studied with respect to acidity of the solution and UV dose. Rate of rolling increased with the acidity of the solution. Tube diameter and rate of rolling decreased with the increase of the UV exposure time. Films with 2-dimensional gradients of layer thicknesses were prepared to study a broad range of parameters in a single experiment. Furthermore, polymer micro-toroids and triangles were also fabricated using self-rolling approach of PS/P4VP layer. Moreover, the kinetics of toroid formation is also studied in the present work. The equilibrium dimensions of toroid are determined by the balance of the bending and the stretching energies of the film. The width of the rolled-up bilayer is larger for the films with higher values of the bending modulus and smaller values of the effective stretching modulus. Moreover, self-rolling phenomena of polymer layer was also explored as a template to fabricate metal, ceramic and metal/ceramic hybrid tube. In order to fabricate metallic and V bimetallic tube, the cross-linked polymer film is capped by metallic layer. After rolling, polymer template is removed by pyrolysis resulting in pure metal microtubes. The fabrication of silica and silica/gold hybrid tubes of high aspect ratio is also demonstrated. Polydimethylsiloxane (PDMS) is used as a precursor of the silica and it is converted into silica by pyrolysis at high temperature. Entire polymer moiety is also removed at this temperature. In order to fabricate hybrid tube of silica with gold, a thin gold layer is deposited on the polymer layer by physical vapour deposition. Self-rolling of polymer bilayers is a very convenient approach for interfacing the interior of microtubes with external electrical circuits and it can be used in particular for creating devices as micro-bubble generators exploiting electrolytic decomposition of fluids. A demonstration of microbubble generation inside the polymer tube is shown in this work. Possibility to functionalize the hidden walls of the tubes is one of the major advantages of the self-rolling approach. One can modify the surface of the film prior to rolling by magnetron sputtering of metal and upon rolling, tube and toroids with metallized inner surface could be obtained. The tube and toroids with metallic inner surface are promising for the future research as IR-frequency range resonators. Polymer and metallic microtubes fabricated by self-rolling approach may find applications in such fields as IR-waveguiding, microfluidics, enzyme bi-reaction, chemical and biochemical sensing. The silica and silica/gold hybrid tubes have potential use in optoelectronic devices and in catalytic applications.

<p>During the last decade, power quality has been recognised asa global problem. Among different types of power qualityproblems, voltage sags have been identified to be one of themost severe problems for different process industries. The mostcommon reason to voltage sags is lightning strikes in powerlines. Protection equipment, usually located at switchyards,disconnect faulted power lines as soon as possible, which isapproximately 100 ms. Thus, the duration of voltage sags areapproximately 100 ms. The sensitivity to voltage sags ofelectrical equipment in process industries can be observed asfor instance malfunction, automatic turnoff or damages.</p><p>This thesis gives an overview of three metals processes withfocus on the sensitivity to voltage sags and interruptions. Theinherent energy in the process is used to find the sensitivity.This energy may also be used to obtain "ride-through" for theprocesses. The three metals processes are a blast furnaceprocess, a hot rolling mill process and a cold rolling millprocess. The main attention in this thesis is paid to the blastfurnace process, which is powered by a line-operatedsynchronous machine.</p><p>The thesis shows that the protection equipment forelectrical machines can be adjusted to avoid unnecessaryshutdowns. It is also explained why there are high torque andcurrents during voltage sags as well as after voltage sags. Itis shown that the first peak torque and current during thevoltage sags is almost proportional to the voltage change, thatis the voltage magnitude before the voltage sag minus thevoltage magnitude during the voltage sag. The first peak torqueand current after the voltage sag depends sinusoidal-like onthe duration of the voltage sag and almost proportional to thevoltage change during the voltage sag. There is no fluxsaturation during voltage sags, however after voltage sagssaturation is very likely to occur. The thesis explains why andalso how the flux is changed during and after voltage sags.</p><p>The duration of voltage sags is in many cases set by theprotection equipment located in switchyards. It is shown thatthe durations of voltage sags can be changed to durations thatwill cause less peak torque and current after voltage sags forline-operated AC-machines. It is also shown how this istheoretically achieved.</p><p><b>Keywords:</b>Rolling mill, Blast furnace, Power Quality,Synchronous machine, Asynchronous machine, Voltage sag, Voltageinterruption, Ride-through, Process disturbances, Simulation,Modelling</p>

Magistrantūros studijų baigiamajame darbe pateikiami padangų riedėjimo pasipriešinimo, lauko sąlygomis, tyrimo duomenys, esant skirtingiems atraminio paviršiaus tipams (pieva, ražiena, sausas žvyrkelis), įvairioms padangų vertikalioms apkrovoms (nuo 1,4 kN iki 5,9 kN) bei skirtingiems oro slėgiams padangoje (nuo 0,5 bar iki 2,0 bar). Darbo objektas – padangos riedėjimo pasipriešinimo koeficientas, jo reikšmės kitimas, esant skirtingiems padangos, apkrovos, ir atraminio paviršiaus parametrams. Tyrimas atliktas naudojant BELCHINA 7.50L – 16 ФБел – 253 padangą. Darbo metodai: padangos tyrimams atlikti buvo suprojektuotas ir pagamintas mobilus stendas, kuris buvo tvirtinamas prie savaeigės važiuoklės T–16M. Darbo rezultatai. Oro slėgis padangoje ir vertikalios apkrovos dydis turėjo įtakos riedėjimo pasipriešinimo koeficiento reikšmių kaitai, esant skirtingiems atraminiams paviršiams (pievoje, ražienoje, sausame žvyrkelyje). Mažinant padangos slėgį riedėjimo pasipriešinimo jėga yra tiesiogiai proporcinga vertikalios apkrovos jėgai ir atvirkščiai proporcinga slėgiui padangoje. Pievoje mažiausia riedėjimo pasipriešinimo jėgos Fp reikšmė gauta esant 1,0 bar slėgiui ir padangą apkrovus 1,4 kN vertikalia apkrova (Fp = 14,375 kN). Ražienoje – esant 0,5 bar slėgiui padangoje, ir 1,4 kN vertikaliai apkrovai (Fp = 22,283 kN). Bandymą atliekant ant žvyrkelio – minimali riedėjimo pasipriešinimo jėgos Fp reikšmė buvo tada, kai padangą veikė 1,4 kN vertikali apkrova ir oro slėgis... [toliau žr. visą tekstą] / The Master’s thesis presents findings of the study of tire rolling resistance under field conditions with different types of support surfaces (grassland, stubble, dry gravel-road), different vertical loads of tires (from 1.4 kN to 5.9 kN) and different air pressures in a tire (from 0.5 bar to 2.0 bar). Object of the thesis – tire rolling resistance coefficient f, change of its values with different parameters of a tire, load and support surface. The study was carried out using the tire BELCHINA 7.50L – 16 ФБел – 253. Methods of the thesis: in order to carry out the tire study, mobile stand was designed and manufactured and attached to self-propelled chassis T – 16M. Results of the thesis. Air pressure in the tire and the value of vertical load influenced the change of rolling resistance coefficient with different support surfaces (grassland, stubble, dry gravel-road). At the tire pressure being decreased, the rolling resistance force was directly proportional to the force of vertical load and is inversely proportional to pressure in the tire. The lowest value of rolling resistance force Fp on grassland was obtained at the pressure of 1,0 bar and vertical load of 1,4 kN on the tire (Fp = 14,375 kN). On stubble – at the pressure of 0,5 bar in the tire and vertical load of 1,4 kN (Fp = 22,283 kN). When the test was performed on dry gravel-road, the minimal value of rolling resistance force Fp was when the tire was affected by vertical load of 1,4 kN and air pressure in the... [to full text]

The aim of this study is to evaluate a methodology for modeling the influence of crystallographic grain orientation on key parameters in normal and sliding contacts. The simulations of interfering cylindrical asperities, using finite element analysis, were conducted using two different plasticity models for copper: a conventional isotropic, homogeneous J2 plasticity model and a continuum crystal plasticity model. A normal contact study was conducted in which crystallographic orientation effects on different parameters were investigated. The model was then adapted for sliding contacts, which allowed other parameters such as energy dissipation to be investigated. Using crystal plasticity, the dependence of crystallographic orientation on plastic deformation and energy dissipation can be determined. The relative trends predicted using crystal plasticity are consistent with experiments that show friction depends on crystallographic orientation when plastic deformation is one of the primary energy dissipation mechanisms.

This dissertation consists of three main parts. The first part is to discuss aileron reversal problem for a typical section with linear aerodynamic and structural analysis. The result gives some insight and ideas for this aeroelastic problem. Although the aileron in its post-reversal state will work the opposite of its design, this type of phenomenon as a design root should not be ruled out on these grounds alone, as current active flight-control systems can compensate for this. Moreover, one can get considerably more (negative) lift for positive flap angle in this unusual regime than positive lift for positive flap angle in the more conventional setting. This may have important implications for development of highly maneuverable aircraft. The second part is to involve the nonlinear aerodynamic and structural analyses into the aileron reversal problem. Two models, a uniform cantilevered lifting surface and a rolling aircraft with rectangular wings, are investigated here. Both models have trailing-edge control surfaces attached to the main wings. A configuration that reverses at a relatively low dynamic pressure and flies with the enhanced controls at a higher level of effectiveness is demonstrated. To evaluate how reliable for the data from XFOIL, the data for the wing-aileron system from advanced CFD codes and experiment are used to compare with that from XFOIL. To enhance rolling maneuverability for an aircraft, the third part is to search for the optimal configuration during the post-reversal regime from a design point of view. Aspect ratio, hinge location, airfoil dimension, inner structure of wing section, composite skin, aeroelastic tailoring, and airfoil selection are investigated for cantilevered wing and rolling aircraft models, respectively. Based on these parametric structural designs as well as the aerodynamic characteristics of different airfoils, recommendations are given to expand AAW flight program.

Today's industry uses increasingly complex machines, some with extremely demanding performance criteria. Failed machines can lead to economic loss and safety problems due to unexpected production stoppages. Fault diagnosis in the condition monitoring of these machines is crucial for increasing machinery availability and reliability. Fault diagnosis of machinery is often a difficult and daunting task. To be truly effective, the process needs to be automated to reduce the reliance on manual data interpretation. It is the aim of this research to automate this process using data from machinery vibrations. This thesis focuses on the design, development, and application of an automatic diagnosis procedure for rolling element bearing faults. Rolling element bearings are representative elements in most industrial rotating machinery. Besides, these elements can also be tested economically in the laboratory using relatively simple test rigs. Novel modern signal processing methods were applied to vibration signals collected from rolling element tests to destruction. These included three advanced timefrequency signal processing techniques, best basis Discrete Wavelet Packet Analysis (DWPA), Matching Pursuit (MP), and Basis Pursuit (BP). This research presents the first application of the Basis Pursuit to successfully diagnosing rolling element faults. Meanwhile, Best basis DWPA and Matching Pursuit were also benchmarked with the Basis Pursuit, and further extended using some novel ideas particularly on the extraction of defect related features. The DWPA was researched in two aspects: i) selecting a suitable wavelet, and ii) choosing a best basis. To choose the most appropriate wavelet function and decomposition tree of best basis in bearing fault diagnostics, several different wavelets and decomposition trees for best basis determination were applied and comparisons made. The Matching Pursuit and Basis Pursuit techniques were effected by choosing a powerful wavelet packet dictionary. These algorithms were also studied in their ability to extract precise features as well as their speed in achieving a result. The advantage and disadvantage of these techniques for feature extraction of bearing faults were further evaluated. An additional contribution of this thesis is the automation of fault diagnosis by using Artificial Neural Networks (ANNs). Most of work presented in the current literature has been concerned with the use of a standard pre-processing technique - the spectrum. This research employed additional pre-processing techniques such as the spectrogram and DWPA based Kurtosis, as well as the MP and BP features that were subsequently incorporated into ANN classifiers. Discrete Wavelet Packets and Spectra, were derived to extract features by calculating RMS (root mean square), Crest Factor, Variance, Skewness, Kurtosis, and Matched Filter. Certain spikes in Matching Pursuit analysis and Basis Pursuit analysis were also used as features. These various alternative methods of pre-processing for feature extraction were tested, and evaluated with the criteria of the classification performance of Neural Networks. Numerous experimental tests were conducted to simulate the real world environment. The data were obtained from a variety of bearings with a series of fault severities. The mechanism of bearing fault development was analysed and further modelled to evaluate the performance of this research methodology. The results of the researched methodology are presented, discussed, and evaluated in the results and discussion chapter of this thesis. The Basis Pursuit technique proved to be effective in diagnostic tasks. The applied Neural Network classifiers were designed as multi layer Feed Forward Neural Networks. Using these Neural Networks, automatic diagnosis methods based on spectrum analysis, DWPA, Matching Pursuit, and Basis Pursuit proved to be effective in diagnosing different conditions such as normal bearings, bearings with inner race and outer race faults, and rolling element faults, with high accuracy. Future research topics are proposed in the final chapter of the thesis to provide perspectives and suggestions for advancing research into fault diagnosis and condition monitoring.