<p>  </p> <p>Part I studies the lubricant sprays and droplets in a rotary compressor. Air conditioning (AC) systems are now widely used in residential and commercial environments, while the compressor is the most important element in the AC system, and rotary compressors are often used in split AC appliances, whose number is estimated to reach 3.7 billion in 2050. In a rotary compressor, the lubricant oil atomizes into small droplets due to the differential pressure in and out of the cylinder. Part of the lubricant oil droplets carried by the refrigerant vapor will ultimately exhaust from the compressor through the discharge pipe. The ratio of the discharged oil volume to the total oil volume is characterized as the Oil Discharge Ratio (ODR). High ODR will reduce the reliability of the compressor and deteriorate the heat transfer of the condenser and the evaporator, resulting in decreased efficiency. Thus, controlling the ODR is a key issue for the design of the rotary compressor.</p> <p>In Part I, rotary compressors were modified to provide optical access into its internal space, i.e., the lower cavity (refers to the space between the cylinder and the motor), above the rotor/stator, and at the discharge tube level. The modified rotary compressors’ operation was supported by a test rig which provided a wide range of operating conditions, e.g., pressure and frequency. Thus, in-situ optical measurements, e.g., shadowgraph and holograph, can be performed to visualize the lubricant sprays and droplets in the rotary compressor. An image processing routine containing the Canny operator and Convolutional Neural-Network was developed to identify droplets from high-resolution shadowgraph images, while Particle Image Velocimetry (PIV) and Optical Flow Velocimetry (OFV) were applied to calculate the spray and droplet’s velocities with time-resolved shadowgraph images. Parallel Four-Step Phase Shifting Holograph (PFSPSH) located the droplets’ positions in a three-dimensional volume under the specific operating condition.</p> <p>Both primary and secondary atomization were observed in the rotary compressor, while primary atomization is the major source of droplet production. The droplet size distributions versus the frequency, vertical direction, radial direction, and pressure are obtained. It is observed that the droplet characteristic mean diameters increase with the frequency and pressure. They also become larger in the outer region above the rotor/stator and keep constant in the radial direction at the discharge tube level. The penetration velocity of the lubricant spray is calculated in the lower cavity. An outward shift of the jet core combined with an outward velocity component was observed. Additionally, horizontal swirling velocity above the rotor/stator and at the discharge tube level and the vertical recirculation velocity above the rotor/stator are characterized. The volume fraction of droplets was also characterized under the specific operating condition. The results provide detailed experimental data to set up the boundary conditions used in CFD. They also show that the droplets in the upper cavity are mostly from the discharge process of the cylinder in the lower cavity. The results support a droplet pathway model in the rotary compressor, which can guide the optimization of future rotary compressors.</p> <p>Evaporation is commonly seen in hydrology, agriculture, combustion, refrigeration, welding, etc. And it always accompanies heat and mass transfer at the liquid-gas interface and is affected by the substance’s properties, the environment’s pressure, temperature, convection, and so on. PFSPSH in Part I aims to retrieve the phase information for holograph reconstruction. Part II further explores the application of the PFSPSH technology in Part I to observe the evaporation process of acetone, where the phase disturbance caused by the vapor is used to reconstruct the vapor concentration in space. The method is called Parallel Four-Step Phase Shifting Interferometer (PFSPSI). The first case studies the evaporation process of the acetone contained in a liquid pool with uniform air flow in a low-speed wind tunnel. The mole fractions of the acetone vapor near the liquid-air interface with different air speeds are characterized. The second case studies the evaporation process of acetone droplets levitated by an ultrasound levitator. The mole fraction of the acetone vapor near the liquid-air interface is characterized by assuming an axisymmetric field and using the analytical solution of the inverse Abel transform. The asymmetric pattern of the acetone vapor field is observed, which is considered due to the drastic sound pressure change at the stand wave location produced by the ultrasound levitator. The mass transfer of the evaporation process by the vapor’s mole fraction is calculated and compared with the mass transfer calculated by the droplet size change. It is observed that the mass transfer by the vapor’s mole fraction is generally smaller than the mass transfer calculated by the droplet size change, which can be explained by the convection process induced by the acoustic streaming.</p>

Electrical machines with more than three phases are usually called multiphase electrical machines and they can have several advantages compared to conventional three-phase electrical machines such as a lower content of space-harmonics, lower torque ripple and better fault tolerance. This degree project involves rewinding of a three-phase induction machine into an asymmetrical six-phase machine. The winding design is based on simulations of a machine model in a finite element method software and the method "the star of the slot" that computes winding layouts. A six-phase drive is developed based on an existing printed circuit board prototype that is not operating according to its original specifications. Debugging of the prototype is performed and solutions to the problems are identified. Design and layout improvements for better electromagnetic compatibility are also implemented. The drive including the electrical machine is tested and confirmed to be working according to the specifications. Speed control based on indirect rotor field orientation is implemented and tested for the six-phase induction machine as well with the machine connected as a standard three-phase induction machine. / Elektriska maskiner med fler än tre faser kallas vanligtvis flerfasiga elektriska maskiner och kan ha flera fördelar jämfört med konventionella trefasiga elektriska maskiner, som lägre innehåll av övervågor, lägre rippel i vridmomentet och bättre feltolerans. Detta examensarbete involverar omlindning av en trefasig asynkronmaskin till en asymmetrisk sexfasig asynkronmaskin. Lindningsdesignen baseras på simuleringar av en maskinmodell i mjukvara baserat på finita element metoden och metoden kallad the star of the slotsom räknar ut lindnings ritningar. En sexfasig drivlina utvecklas baserat på en existerande kretskorts prototyp som inte fungerar enligt dess ursprunliga specifikationer. Felsökning av prototypen utförs och lösningar till problemen identifieras. Design- och layoutförbättringar för bättre elektromagnetisk kompatibilitet implementeras också. Drivlinan med den elektriska maskinen inkluderad testas och bekräftas fungera enligt dess specifikationer. Hastighetsreglering baserad på indirekt rotorfälts orientering implementeras och testas för den sexfasiga asynkronmaskinen samt även med maskinen kopplad som en standard trefas asynkronmaskin.

<p dir="ltr">Neural operator learning is emerging as a prominent technique in scientific machine learn- ing for modeling complex nonlinear systems with multi-physics and multi-scale applications. A common drawback of such operators is that they are data-hungry and the results are highly dependent on the quality and quantity of the training data provided to the models. Moreover, obtaining high-quality data in sufficient quantity can be computationally prohibitive. Faster surrogate models are required to overcome this drawback which can be learned from datasets of variable fidelity and also quantify the uncertainty. In this work, we propose a Multi-Level Stacked Deep Operator Network (MLSDON) which can learn from datasets of different fidelity and is not dependent on the input function. Through various experiments, we demonstrate that the MLSDON can approximate the high-fidelity solution operator with better accuracy compared to a Vanilla DeepONet when sufficient high-fidelity data is unavailable. We also extend MLSDON to build robust confidence intervals by making conformalized predictions. This technique guarantees trajectory coverage of the predictions irrespective of the input distribution. Various numerical experiments are conducted to demonstrate the applicability of MLSDON to multi-fidelity, multi-scale, and multi-physics problems.</p>

<p dir="ltr">Powder Sprays such as Direct Energy Deposition and Cold Spray are rapidly growing and promising manufacturing methods in the Additive Manufacturing field, as they allow easy and localized delivery of powder to be fused to a substrate and consecutive layers. The relatively small size of nozzles allows for these methods to be mounted on CNC machines and Robotic Arms for the creation of complex shapes. However, these manufacturing methods are inherently stochastic, and therefore differences in powder size, shape, trajectory, and velocity can drastically affect whether they will deposit on a substrate. This variation results in an inherent reduction of deposition efficiency, leading to waste and the need for powder collection or recycling systems. The design of the nozzles can drastically affect the variation of powder trajectory and velocity on a holistic level, and thus understanding the gas-powder flow of these nozzles in respect to the features of said nozzles is crucial. This paper proposes and examines how changes in the nozzle geometry affect gas-powder flow and powder focusing for Direct Energy Deposition and Cold Spray. In addition, a new Pulsed Cold Spray nozzle design is proposed that will control the amount of gas and powder used by the nozzle via solenoid actuation. By making these changes to the nozzle, it is possible to improve deposition efficiency and reduce powder/gas waste in these processes, while also allowing for improved coating density. Furthermore, the research done in this thesis will also focus on novel applications to powder spray manufacturing methods, focusing on polymer metallization and part identification.</p>

<p dir="ltr">Interest in using detonation-based combustion cycles for use propulsion and power generation has gained considerable attention in the last 10 years or so. The rotating detonation engine (RDE), in particular, has garnered the most attention as a possible replacement for current generation combustion systems. RDEs are continuous flow devices that typically operate in a non-premixed fashion. Reactants are injected into an annular combustion chamber that is usually several millimeters wide. One or more detonation waves propagate azimuthally around the annulus, consuming the reactants. The products then expand out of the combustor where it can produce thrust or be passed into a turbine. The detonation wave front in RDEs travel at speeds between 1-3 km/s which poses additional complexity beyond traditional combustors. There are large gaps in the research community for RDEs that use one or more liquid based propellants. Questions regarding liquid breakup, atomization, breakup, recovery all remain unanswered both experimentally and numerically. This work seeks to understand these fundamental physical phenomena that drive these devices by applying advanced, high-speed laser and other optical diagnostics. </p><p dir="ltr"> A 120 mm nominal diameter rotating detonation combustor that operates on non-premixed hydrogen-air was modified to remove a hydrogen orifice and was replaced with a single liquid fuel injector. This simple, yet important, modification enables the study of a one-way coupling between a liquid fuel jet and a detonation wave at relevant spatio-temporal scales. Planar laser-induced fluorescence was performed at rates up to 1 MHz to quantify the quasi-steady jet dynamics and the recovery behavior of the single liquid jet. Long-duration PLIF imaging lasting 30-40 detonation periods at 300 kHz was also performed for statistical significance. A diesel liquid-in-crossflow injector was observed to breakup or be removed from the PLIF plane within only a few microseconds. After the detonation wave passes through the spray there is a significant dwell period can last between 20-40% of the detonation period before the new fuel is issued into the channel. The quasi-steady liquid jet trajectory was also compared to a jet-in-crossflow from literature and there is decent agreement in the jet near-field. </p><p dir="ltr"> The same hardware scheme with a different liquid fuel injector was tested in conjunction with an alternative imagine scheme. The first technique was able to capture details in the radial-axial plane but could not resolve any motion in the azimuthal direction. A volume-based illumination scheme was used for LIF to image a liquid fuel jet in the azimuthal-axial plane. For this experiment the location of the liquid fuel jet was moved into a different position and as a result experiences significantly different behavior than the jet in crossflow. The breakup and evaporation process takes place over a much longer period of time and there is no pause of liquid fuel injection. Similarly, LIF was performed at 300 kHz for 30 detonation cycles to enable sadistically quantification and phase averaging. Filtered OH* and CH* chemiluminescence imaging was also performed over the same field of view as the LIF imaging. Estimation of the velocity field was calculated using optical flow from the Jet-A LIF images. The velocity results agree well with the recovery analysis from the PLIF measurements.</p><p dir="ltr"> Using the same liquid fuel injection scheme, Jet-A droplet diameter and velocity was measured <i>in-situ</i> during a hot-fire experiment using phase Doppler interferometry (PDI). Although a point technique, PDI was used to measure thousands of droplets during a single test at multiple locations and with multiple conditions. As a means of comparison, cold flow experiments were performed with water in the exit plume. Droplet diameters were measured between 1-20 µs in both cases. PDI results were compared with the optical flow results and there is agreement in median velocities and some differences in the minimum and maximum velocity values. Possible sources of error in the diameter measurement are discussed as well.</p>

<p dir="ltr">The foundation of numerical codes used in engineering analyses of two-phase flows is the two-fluid model (TFM). However, the TFM codes use artificial regularization to remove the high frequency ill-posed instability in the numerical solution. This work demonstrates that incorporating variational inertial coupling terms to the numerical two-fluid model code, makes it more complete, objective and well-posed without the need for any regularization. The variational TFM is implemented in an industrial CFD code and the two-fluid Burgers problem is used to verify the numerical TFM against analytic solutions.</p>

2012年3月28日爆發的文林苑事件，北市府對於王家的合法獨立建物執行強制拆除，該建物無礙公共安全，且由外觀上看來並無都更之必要。王家與其支持者誓死抵抗，同意戶因原有房屋早被拆除而返家無期亦備受煎熬，預售屋的買主亦稱自己才是真正受害者，同時間政府與實施者皆堅稱一切都是「依法行事」:依照「都市更新條例」。文林苑事件引起的質疑與辯論迄今未歇，公權力之發動是否與重要公益失去連結？都更法制之設計與運作是否向建商不當傾斜？民眾之權利救濟於實體或程序上是否有不當障礙？ 2013年4月26日，司法院釋字第709號解釋宣告都更條例若干條款不符憲法要求之正當行政程序，相關機關應就違憲部分檢討修正。值此修法之際，正是對都更體制全面體檢的良好時機。本文將聚焦於民辦都更模式，依都更條例的多階段行政程序設計，深入檢視各階段中政府行政行為之法律性質與救濟途徑、分析造成重大爭議之條款所牽動之公法或私法關係、探究法規之實體與程序規定是否合宜、並歸納實務判決對於都更法律之適用與解釋原則，冀能提供修法之適切建議。 整體觀之，無論是採協議合建或是權利變換方式，民辦都更體制所採取的多階段行政程序，於一開始自行劃定更新單元時就與重要公益失去有效連結，而於「事業計畫」與「權利變換計畫」階段就個案之公益性與必要性亦無具體之檢驗標準。隨著程序之遞進，對於不同意者之基本權限制逐漸加深，但對不同意者權利之保護卻逐漸弱化，甚至在執行階段導致不同意者之財產權與居住自由被完全剝奪。此種法制之設計思維亦反映在實際運作上，政府傾向與實施者站在同一立場，在「大多數人之私益等於公共利益」與「加速都更」此理所當然之脈絡下，不同意者之權益經常被忽略，且被迫負擔不成比例的不良後果。 確實，就不同意者之權益保障，都更體制之設計於各階段中無論在實體與程序方面均有欠缺之處，尤其是執行階段，實施者得借用公權力之設計更讓整個都更體制朝實施者偏斜而去，致不同意者與實施者間所產生之私權關係嚴重失衡。而於行政救濟方面，法院傾向尊重審議會之判斷餘地而採寬鬆立場，故就行政行為對地主權益之侵害是否合理與正當，似易錯失再度檢驗之機會。 本文主要建議，政府劃定更新地區時，應確保民眾之程序參與並明白揭示其救濟之道；於事業計畫核定前，宜准許地主撤銷同意書；於權利變換階段，應增設同意機制，估價師之選定與委任宜讓地主參與，審議核復之救濟程序應予明文釐清；於執行階段，因強拆與強徵手段不符公益與比例原則，恐不宜適用於民辦都更案件。 總括而言，現行都更之法律體制一律以單純「國家與人民」之公法二維思維來規範都更事務，自對當事人間私益之權衡欠缺考量。尤其民辦都更主要涉及以私法為本質的私權關係，此種因循公法框架之制度設計，更無法平衡兼顧各方私益之調和。本文亦贊同，都更之實施應以公辦都更為主要之模式，俾能與上位的都市計畫產生有效的連結，並較可能基於公益之理由而發動公權力。至於民間發動之都更，因多以追逐私益為主要目的，政府之介入既無法確保權利人間利益之公平分配，又無法提供與公益之有效連結，在無都更必要性與急迫性之情形，則以回歸傳統私法自治之範疇，經全體同意為宜。 惟重要的是，無論是民辦與公辦都更，應訂定具體之公益檢驗標準，並區分都更之必要性與急迫性，以分級制度適用寬嚴不同的程序，且應於各階段設計針對個別建物公益性與必要性之評估機制。尤其，強制拆除與強制徵收都必須節制為最後手段，僅宜運用在情況最為急迫嚴重之案例。如此，始能期待各方當事人與社會大眾同享都更之果實。 / On 28 March 2012, the Taipei City Government exercised its authority to evict the homeowners and tear down the buildings, which were legally and exclusively owned by the Wang family refusing to take part in the urban renewal project. Neither did the buildings pose any existing threat to public safety, nor did it show any urgent need for urban renewal. Thus, the so-called “Wen-Lin Yuan Incident” sparked a series of confrontation: The Wang family and its supporters vowed to defend homes with their lives； the 36 households taking part in the project hoped to speed up the construction, because their houses have long been demolished by developer； the buyers of the pre-sale houses said they were also the innocent victims； meanwhile the private developer and the city government insisted that their handling in this case has been adhering to the law-The Urban Renewal Act. The debates and questions ignited in this dispute have sustained and continued till now: Does the exercise of official authority well connect with the purpose of important public interest? Are the Urban Renewal Act and the related regulations designed and used to favor developers? Is there unreasonable substantive or procedural obstacles on legal remedies for residents? On 26 April 2013, the Justices of the Constitutional Court issued J.Y. Interpretation No. 709, which declared some provisions of the Urban Renewal Act do not comply with the due process in administrative procedures required by the Constitution and the unconstitutional parts of the provisions should be reviewed and amended by the relevant authorities. It’s time to fully re-examine the current urban renewal laws. Based on the multiphase-administrative-procedural model, the Urban Renewal Act governs and facilitates the renewal projects initiated by both private and public sector. This thesis focuses solely on the issues of private-initiated renewal projects. Within each phase, by examining in detail the legal nature and remedies of government decisions or actions, analyzing how controversial statutes influencing the relationship between individuals and the government and the relationship between individuals, exploring if the substantive or procedural provisions are appropriate, and generalizing legal principles enunciated and embodied in judicial decisions, hope this thesis can make meaningful suggestions for the amendment of the law. From an overall perspective, no matter what the method taken- “Rights Transformation” or “Joint Construction Agreement”, starting from the early phase of “business summary”, in which the law allows property owners to designate the renewal units by themselves, the legal system on the private-initiated urban renewal causes great risk of losing effective connection to an important public-interest purpose. Moreover, in the “business plan” and “rights- transformation plan” phases, the law lacks clear standards or criteria to check if the specific case meets the proportionality principle and whether the public interest is best served. As each phase involves different government decisions, the restrictions on the property right of dissenting owners grow bigger, yet the mechanism for their rights protection becomes weaker, eventually in the final “execution” phase, the dissenting owners could be completely deprived of their property right and freedom of residence. When it comes to the practical application, following this legal structure’s line of reasoning, the administrative agency tends to act in concert with implementer (mostly private developer), both parties interpret public interest as the sum of most private interests and aim at speeding up the whole process, so that the dissenting property owners’ rights are usually overlooked and the dissents are forced to shoulder a disproportionate share of the negative effects. Actually, for the property owners refusing to join the project, the law fails to provide proper protection no matter substantively or procedurally. Especially in the “execution” phase, the implementers are entitled to request the government to demolish or expropriate the property. Thus, through the indirect transfer of public power to the implementer, the law impairs the supposed-to-be-fair balance between the rights of the property owners and the rights of the implementer. On the other hand, in administrative judicial proceedings, given that administrative courts often defer to the discretion of expert committee set up by administrative agency for the review of renewal projects, it is unsurprising that the courts tend to adopt administrative agency’s litigation interpretation. Thus, when property owners’ fundamental constitutional rights are infringed, the administrative action may not be under adequate scrutiny by courts. This thesis proposes that: in the first phase when designating the renewal area, the administrative agency should ensure an open and transparent public participation, and after decision made, especially for those most affected in the renewal area, including property owners and residents, the legal remedy should be clearly specified in the law； before the “business plan” approved and announced by administrative agency, property owners should be allowed to withdraw their letter of consent unconditionally； in “rights- transformation plan” phase, the consent mechanism should be added into the process, property owners should be entitled to participate in selecting and entrusting real estate appraisers, the special “disagreement inspection procedure” should be well-clarified and defined in law； in the last “execution” phase, the use of forced demolition or expropriation as a legal instrument to take private property for private-initiated renewal projects, cannot be justified under the principle of proportionality and public interest. Thus, the related unconstitutional regulations need to be modified. In short, the current urban renewal laws are designed under the framework of governing the relationships between government and individuals. As for the relationship between individuals, especially in the now dominating private-initiated mode, this original design is inherently flawed to balance the diverse and competing interests among different private parties. In essence, all urban renewal projects should conform to the overall urban plan adopted and formulated by the city government. Besides, the use of authority and power can be legitimate only when implementing public purpose and public benefits. Given that the government-initiated mode is more likely to be consistent with the comprehensive urban plan and be aligned with public interest, this thesis suggests that government take the responsibility to lead and initiate most urban renewal projects. As for the private-initiated mode, which mostly driven by short-term private profits, the current government intervention can neither ensure equitable distribution of benefit among stakeholders, nor can it provide a significant link to public interest, thus, better leave it to the traditional realm of private law, that is, if there is no necessity or urgency, reconstruction shall require the consent of all property owners. If the public and private modes are to be maintained and co-exist in the urban renewal system, both laws should contain concrete guidelines and standards on factors that should be taken into account in determining if the designation of renewal areas or units is in pursuit of important public interest. Besides, a priority rating system should be established based on the degree of need and urgency to categorize the different procedural implementation, aiming to ensure a direct correlation between the degree of government intervention and the degree of need and urgency. Furthermore, an assessment tool of the necessity and proportionality is required to be built in each phase, thus to help administrative agency decide whether in the particular case, the public interest outweighs the interests adversely affected. In all cases, the use of eminent domain and forced demolition should be reserved as the last resort for the most serious conditions. Hopefully, by the aforementioned amendments, the promised fruits of urban renewal can be available not only to the parties involved but also to the general public.

This dissertation is a contribution to the development of a unified model of continuum mechanics, describing both fluids and elastic solids as a general continua, with a simple material parameter choice being the distinction between inviscid or viscous fluid, or elastic solids or visco-elasto-plastic media. Additional physical effects such as surface tension, rate-dependent material failure and fatigue can be, and have been, included in the same formalism. The model extends a hyperelastic formulation of solid mechanics in Eulerian coordinates to fluid flows by means of stiff algebraic relaxation source terms. The governing equations are then solved by means of high order ADER Discontinuous Galerkin and Finite Volume schemes on fixed Cartesian meshes and on moving unstructured polygonal meshes with adaptive connectivity, the latter constructed and moved by means of a in- house Fortran library for the generation of high quality Delaunay and Voronoi meshes. Further, the thesis introduces a new family of exponential-type and semi- analytical time-integration methods for the stiff source terms governing friction and pressure relaxation in Baer-Nunziato compressible multiphase flows, as well as for relaxation in the unified model of continuum mechanics, associated with viscosity and plasticity, and heat conduction effects. Theoretical consideration about the model are also given, from the solution of weak hyperbolicity issues affecting some special cases of the governing equations, to the computation of accurate eigenvalue estimates, to the discussion of the geometrical structure of the equations and involution constraints of curl type, then enforced both via a GLM curl cleaning method, and by means of special involution-preserving discrete differential operators, implemented in a semi-implicit framework. Concerning applications to real-world problems, this thesis includes simulation ranging from low-Mach viscous two-phase flow, to shockwaves in compressible viscous flow on unstructured moving grids, to diffuse interface crack formation in solids.