Целью работы является повышение конкурентоспособности и расширение номенклатуры продукции предприятия полного металлургического цикла за счёт совершенствования третьего передела. Были разработаны основные методики и сформулированы требования для внедряемых мероприятих по установке гидросбива окалины, автоматизации синхронизации клетей, системы измерения геометрии прокатываемого профиля, устройства ускоренного охлаждения проката и внедрение новых марок сталей. / The aim of the work is to increase the competitiveness and expand the product range of the enterprise of the full metallurgical cycle by improving the third processing. The main methods were developed and requirements were formulated for the implemented measures for the installation of a hydraulic scale breaker, automation of the synchronization of stands, a system for measuring the geometry of the rolled profile, devices for accelerated cooling of rolled products and the introduction of new steel grades.

Small-scale fracture behavior of four model alloy systems were investigated in the order of increasing microstructural complexity, namely: (i) a Ni-based Bulk Metallic Glass (Ni-BMG) with an isotropic amorphous microstructure; (ii) a single-phase high entropy alloy, HfTaTiVZr, with body centered cubic (BCC) microstructure; (iii) a dual-phase high entropy alloy, AlCoCrFeNi2.1, with eutectic FCC (L12) -BCC (B2) microstructure; and (iv) a Medium-Mn steel with hierarchical microstructure. The micro-mechanical response of these model alloys was investigated using nano-indentation, micro-pillar compression, and micro-cantilever bending. The relaxed Ni-BMG showed 6% higher hardness, 22% higher yield strength, and 26% higher bending strength compared to its as-cast counterpart. Both the as-cast and corresponding relaxed BMGs showed stable notch opening and blunting during micro-cantilever bending tests rather than unstable crack propagation. However, pronounced notch weakening was observed for both the structural states, with the bending strength lower by ~ 25% for the notched samples compared to the un-notched samples. Deformation behavior of HfTaTiVZr was evaluated by micropillar compression and micro-cantilever bending as a function of two different grain orientations, namely [101] and [111]. The [111] oriented micropillars demonstrated higher strength and strain hardening rate compared to [101] oriented micropillars. The [111] oriented micropillars showed transformation induced plasticity (TRIP) in contrast to dislocation-based planar-slip for the [101] oriented micropillars, explaining the difference in strain hardenability for the two orientations. These differences in deformation behavior for the two orientations were explained using Schmid factor calculations, transmission electron microscopy, and in-situ deformation videos. For the dual-phase AlCoCrFeNi2.1 high entropy alloy, the L12 phase exhibited superior bending strength, strain hardening, and plastic deformation, while the B2 phase showed limited damage tolerance during bending. The microstructure and deformation mechanisms were characterized for a few different medium-Mn steels with varying carbon (0.05-0.15 at%) and manganese (5-10 at%) content. The alloy with 10 at% Mn and 0.15 at% C (1015 alloy) showed hierarchical microstructure of retained austenite and ferrite with lamellae 200 nm to 300 nm wide. Micro-pillar compression at different strain levels for this alloy revealed that deformation in austenite is primarily accommodated through transformation to martensite, thereby increasing the strain hardening rate.

No description available.

No description available.

No description available.

Today's civil engineering structures are most often designed through a trial anderror approach, which means that the designer tests a design solution andevaluates whether all requirements are met. If any of the requirements are notmet, changes are made to the design until a feasible solution is obtained. It is atime-consuming process where the  nal design is not always optimal concerningmaterial consumption. In this study, a program has been developed in MATLAB®for the design of reinforced concrete retaining walls and by using optimizationalgorithms, the design process has been made automated and time-ecient. Theuse of optimization algorithms also allows for  nding a solution that is not onlyfeasible but also optimal. The developed program utilizes two objective functions,minimizing environmental impact or investment cost based on materialconsumption. In addition, the design calculations are developed according toEurocode and additional national requirements of Swedish standards.This thesis presents the background to the study, fundamental optimization theoryand how the developed program is designed. A case study is also presented whereexisting retaining walls have been examined to evaluate what savings could havebeen made using optimization algorithms in the design process. Lastly, guidelinesare also presented for designers to facilitate the choice of cross-sectional dimensionsand reinforcement bar dimensions when designing retaining walls.The results obtained in the case study show that using optimization algorithms inthe design process can make signi cant savings (10-20%) on investment cost andenvironmental impact. Moreover, the results show that an optimized retaining wallconcerning environmental impact also leads to a substantial reduction ininvestment costs and vice versa.

<p>This work explores a new method of force generation for flying robots on the sub-cm wingspan scale: resonant curved piezoelectric cantilevers created using completely parallel MEMS fabrication. It theorizes that because a resonating curved beam has a different drag coefficient on the upstroke than the downstroke, it should act as a fluid diode: a partial one-way gate for fluids, and thereby generate an asymmetric force over a symmetric one-degree-of-freedom flapping cycle. It develops a simplified model for the large-amplitude resonant mode of thin circular arcs by analytically extending the resonant mode shape of straight cantilevers, shows that this shape is a better fit to experimental data than previous models, and shows that it accurately predicts the resonant frequency. It uses this resonant mode to compute the force on flapping curved arcs under a wide range of amplitudes, Reynolds numbers, and arc angles using computational fluid dynamics (CFD) simulations, and extends the concept of a drag coefficient from steady-flow fluid mechanics to steady-state oscillatory fluid mechanics both for net force generation and power dissipation. It develops a framework to analyze the CFD results in the broader context of a complete robot, and uses this framework to determine priorities for material selection, robot size, and flapping shape, depending on desired robot application. It tests these theoretical predictions by creating prototype 7.6 mm wings out of 7.5 micrometer thick x-cut quartz and SU-8, after developing and implementing a method to smoothly thin x-cut quartz leaving the surface free of dielectric-compromising pits using reactive ion etching (RIE). Finally, it constructs a test chamber to measure the force, amplitude, and electrical parameters of the flapping wings under a variety of air pressures and demonstrates that the results are consistent with the theoretical predictions, indicating that this approach can in fact lead to successful flying microrobots.</p> / Doctor of Philosophy (PhD)

The research presented in this dissertation supports the overall goal of creating piezoelectric measurement technology for the analysis and characterization of soft materials that serve as feedstocks (inputs) and products (outputs) of emerging biomanufacturing processes, including cell and additive biomanufacturing processes. The first objective was to define measurement challenges associated with real-time monitoring of material compositional profiles using biosensors in practical biomanufacturing and bioprocessing formats, as insight into a material's composition (i.e., concentration of a given biologic within a material or product) provides molecular-scale insight into processes and product quality. The second objective was to design, fabricate, and characterize continuous flow cell separation technology based on 3D printed self-exciting and -sensing millimeter-scale piezoelectric transducers and microfluidic networks for separation and characterization of expanded therapeutic cells. The third objective was to establish a sensor-based characterization approach for viscoelastic properties of hydrogels and gelation processes using high-order modes of piezoelectric-excited millimeter cantilever (PEMC) sensors and understand the influence of cantilever mode number on critical sensor characteristics, including sensitivity, dynamic range, and limit of detection. The first objective was addressed through a comprehensive review of recent progress in electrochemical and hybrid biosensors, which included discussions of measurement formats, sensor performance, and measurement challenges associated with use in practical bioprocessing environments. This critical review revealed that cost, disposability, form factor, complex measurement matrices, multiplexing, and sensor regeneration/reusability are among the most pressing challenges that require solutions through advancement of sensor design and manufacturing approaches before biosensors can facilitate high-confidence long-term continuous bioprocess monitoring. The second objective was addressed by creating a microextrusion-based additive manufacturing approach for fabrication of piezoelectric-based MEMS devices that enabled integration of 3D configurations of piezoelectric transducers and microfluidic networks in a one-pot manufacturing process. The devices contained orthogonal out-of-plane piezoelectric sensors and actuators and generated tunable bulk acoustic waves (BAWs) capable of size-selective manipulation, trapping, and separation of suspended particles in droplets and microchannels. This work suggests that additive manufacturing potentially provides new opportunities for the fabrication of sensor-integrated microfluidic platforms for cell culture analysis. The third objective was addressed through resonant frequency tracking of low- and high-order modes in dynamic-mode cantilevers to enable the real-time characterization of hydrogel viscoelastic properties and continuous monitoring of sol-gel phase transitions over a wide dynamic range using practically relevant hydrogel systems used commonly in additive biomanufacturing. This work suggests that high-order modes of PEMC sensors facilitate characterization of hydrogel viscoelastic properties and gelation processes with improved dynamic range and limit of detection that can complement the performance of low-order modes. Through this research, new approaches for sensor-based characterization of soft material composition and mechanical properties using millimeter-scale piezoelectric devices are presented as solutions for current challenges in biomanufacturing and biosensing to advance capability in real-time sensing of quality attributes among biomanufactured products. / Doctor of Philosophy / The research presented in this dissertation supports the overall goal of creating sensor-based measurement technology for quality assessment of soft materials within practical online biosensing and biomanufacturing processing formats. This technology seeks to enable monitoring and control of product quality in real-time. Soft biomaterials used in these processes, including cells and hydrogels, can be characterized by quality signatures such as concentration of analytes and physical and mechanical properties. Separation and fluid handling technologies aid real-time characterization when integrated with the processing system. By improving sensor-based measurement capability of soft materials, sensing platforms can provide online quality assurance and control, thereby increasing the product quality and process efficiency – or yield– at reduced cost. The first objective was to define measurement challenges and limitations associated with detection of biologics in practical biomanufacturing and bioprocessing formats (with focus on pathogen detection, as the detection of adventitious agents and pathogens remains a critical aspect of bioprocess monitoring). This was addressed through a comprehensive review of recent progress in the field of electrochemical and hybrid biosensors. The second objective was to design and fabricate sensor-integrated microfluidic technology for cell separation applications using a combination of multi-material 3D printing and pick-and-place techniques. The third objective was to improve measurement capability of piezoelectric sensors for characterization of viscoelastic properties of hydrogel formulations commonly used in additive biomanufacturing processes and tissue engineering. Through this research, new approaches for sensor-based characterization of soft materials using millimeter-scale piezoelectric devices are presented as solutions for current challenges in biomanufacturing and biosensing platforms in order to advance quality assessment capability.

The primary direction of this thesis was towards exploring qualitative and quantitative characteristics necessary for refining and understanding the flat wood double cantilever beam (DCB) as a valid means for testing Mode I fracture energy in wood adhesive bonds. Southern yellow pine (SYP) adherends were used with epoxy and phenol formaldehyde (PF) impregnated films, providing two systems with different characteristics for investigation. An adhesive penetration analysis was performed for both the epoxy and PF bonds. The PF penetration into the SYP was shown to be relatively shallow. The epoxy penetration was shown to be deeper. Epoxy-SYP DCBs were quasi-statically tested with varying widths (10 mm, 15 mm, and 20 mm), showing decreases in scatter of critical and arrest strain energy release rates, GIc and GIa, with increases in specimen width. Quasi-static fracture testing was also performed on PF SYP-DCBs, showing much higher critical and arrest fracture energy values than the epoxy-SYP DCBs, indicating that deep adhesive penetration is not necessarily a requisite for higher Mode I fracture energy values. Grain distribution influences were computationally investigated because of the stiffness difference between latewood and earlywood growth and the grain angle along the length of the beams. The grain angle and the stiffness difference between latewood and earlywood growth caused the effective stiffness, (ExxI)eff, to vary along the length of the beam. The effective stiffness variation caused variations in the beam's ability to receive and store strain energy, complicating and confounding determination of experimental results. Cyclic loading tests were performed on PF-SYP DCB's. The cycle frequency was 3Hz, with a valley to peak load ratio of R = 0.5. Specimen softening was observed with cycling, with re-stiffening occurring with crack growth. Contrary to expectations, specimen compliance occasionally decreased with small crack extensions. A toughening mechanism was frequently observed, whereby subsequent crack lengths required more cycles to failure than the previous crack length. Monotonically extending the crack length far from the fatigued region created a fresh crack that did not show the toughened behavior. But toughening did resume with subsequent crack lengths. / Master of Science

Different means and methods exist in the construction industry to erect bridge superstructures. In planning and execution of the complex construction operations the effects of the chosen erection method need to be considered to achieve a safe and economical process. Failures of bridges under construction have underlined the importance of this issue. Hence, constructability issues need to be considered from the very beginning of projects. Structural analysis mathematically models geometry, boundary conditions, and other structural details, material properties, and so-called actions and incorporates factors of safety. Aforementioned actions, i.e. loads or restraints of deformations may act only temporarily during construction, depending on the method and sequence of erection. However, these construction loads can create considerable stresses in the unfinished structure prior to completion when it still lacks additional redundancy against failure. Furthermore, time-dependent material properties such as creep, shrinkage, and relaxation play a major role, especially in segmental construction. A case study is provided as an example of how constructability issues are dealt with in engineering practice. The Wilson Creek Bridge is a five-span cast-in-place concrete segmental bridge that was erected with Balanced Cantilever Construction. The bridge superstructure incorporated a camber to account for time-dependent deflections in final alignment. Form travelers were used in an alternating manner about the bridge piers to construct cantilever arms that were finally connected at midspan. These travelers remained in place until the box girder segments had reached sufficient strength to be post-tensioned to their predecessors. Casting cycle duration on this project was one week. / Master of Science