Since their invention in the early 1900s, Tuned Vibration Absorbers (TVAs) have shown to be effective in suppressing vibrations of machines and structures. A vibration absorber is a vibratory subsystem attached to a primary system. It normally consists of a mass, a spring, and a damper. Mounted to the primary system, a TVA counteracts the motions of the primary system, "absorbing" the primary structure's vibrations. A conventional passive TVA, however, is only effective when it is tuned properly, hence, the name "tuned" vibration absorber. In many practical applications, inevitable off-tuning (or mistuning) of a TVA occurs because of the system's operating conditions or parameter changes over time. For example, the mass in a building floor could change by moving furnishings, people gathering, etc., which can "off-tune" TVAs. When TVAs are off-tuned, their effectiveness is sharply reduced. Moreover, the off-tuned TVAs can excessively amplify the vibration levels of the primary structures; therefore, not only rendering the TVA useless but also possibly causing damage to the structures. Off-tuning is one of the major problems of conventional passive TVAs. This study proposes a novel semiactive TVA, which strives to combine the best features of passive and active TVA systems. The semiactive TVA in this study includes a Magneto-Rheological (MR) damper that is used as a controllable damping element, for providing the real-time adjustability that is needed for improving the TVA performance. This study is conducted in two phases. The first phase provides a numerical investigation on a two-degree-of-freedom (2-DOF) numerical model in which the primary structure is coupled with a TVA. The numerical investigation considers four semiactive control methods for the MR TVAs, in addition to an equivalent passive TVA. These numerical models are optimally tuned using numerical optimization techniques to compare each TVA system. These tuned systems then serve as the basis for numerical parametric studies for further evaluation of their dynamic performance. The parametric study covers the effects of damping, as well as system parameter variations (off-tuning). The results indicates that semiactive TVAs are more effective in reducing the maximum vibrations of the primary structure and are more robust when subjected to off-tuning. Additionally, the numerical study identifies the "On-off Displacement-Based Groundhook control (on-off DBG)" as the most suitable control method for the semiactive TVA among control methods considered in this study. For the second phase of this study, an experimental study is performed on a test setup, which represents a 2-DOF structure model coupled with an MR TVA. Using this setup, a series of tests are conducted in the same manner as the numerical study to evaluate the performance of the semiactive TVA. The primary purposes of the experiment are to further evaluate the most promising semiactive control methods and to serve as a "proof-of-concept" of the effectiveness of this MR TVA for floor vibration applications. The results indicate that the semiactive TVA with displacement-based groundhook control outperforms the equivalent passive TVA in reducing the maximum vibrations of the primary structure. This confirms the numerical result that identifies on-off DBG control method as the "best" control method for the MR TVA among four semiactive control schemes considered. The experimental robustness study is also conducted, focusing on the dynamic performance of both the passive and the semiactive TVAs when the mass of the primary system changes (mass off-tuning). The mass of the primary system varied from -23 % to +23 % of its nominal value by adding and removing external masses. The experimental results show that the semiactive TVA is more robust to changes in the primary mass than the passive TVA. These results justify the benefits of the use of semiactive MR TVAs in structures, such as building floor systems. The off-tuning analysis further suggests that, in practice, semiactive TVAs should be tuned slightly less than their optimum in order to compensate for any added masses to the structure. Additionally, the lessons learned from the experimental study have paved the way for implementing the semiactive MR TVA on a test floor, which is currently in progress under a separate study. / Ph. D.

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<div>Silicon based semiconductor technology is facing more and more challenges to continue the Moore's law due to its fundamental scaling limitations. To continue the pace of progress of device performance for both logic and memory devices, researchers are exploring new low-dimensional materials, e.g. nanowire, nanotube, graphene and hexagonal boron nitride. Transition metal dichalcogenides (TMDs) are attracted considerable attention due their atomically thin nature and proper bandgap at the initial study. Recently, more and more interesting properties are found in these materials, which will bring out more potential usefulness for electronic applications. Competing with the silicon device performance is not the only goal in the potential path finding of beyond silicon. Low-dimensional materials may have other outstanding performances as an alternative materials in many application realms. </div><div><br></div><div>This thesis explores the potential of TMD based devices in memory and logic applications. For the memory application, TMD based vertical devices are fully studied. Two-terminal vertical transition metal dichalcogenide (TMD) based memory selectors were firstly built and characterized, exhibiting better overall performance compared with some traditional selectors. Polymorphism is one of unique properties in TMD materials. 2D phase engineering in TMDs attracted great attention. While electric switching between semiconductor phase to metallic phase is the most desirable. In this thesis, electric field induced structural transition in MoTe₂ and Mo_1-xW_xTe₂ is firstly presented. Reproducible bipolar resistive random access (RRAM) behavior is observed in MoTe₂ and Mo_1-xW_xTe₂ based vertical devices. Direct confirmation of a phase transition from a 2H semiconductor to a distorted 2H_d metallic phase was obtained after applying an electric field. Set voltage is changed with flake thickness, and switching speed is less than 5 ns. Different from conventional RRAM devices based on ionic migration, the MoTe₂-based RRAMs offer intrinsically better reliability and control. In comparison to phase change memory (PCM)-based devices that operate based on a change between an amorphous and a crystalline structure, our MoTe₂-based RRAM devices allow faster switching due to a transition between two crystalline states. Moreover, utilization of atomically thin 2D materials allows for aggressive scaling and high-performance flexible electronics applications. Both of the studies shine lights on the new application in the memory field with two-dimensional materials.<br></div><div><br></div><div>For the logic application, the ultra thin body nature of TMDs allows for more aggressive scaling compared with bulk material - silicon. Two aspects of scaling properties in TMD based devices are discussed, channel length scaling and channel width scaling. A tunability of short channel effects in MoS₂ field effect transistor (FET) is reported. The electrical performance of MoS₂ flakes is governed by an unexpected dependence on the effective body thickness of the device which in turn depends on the amount of intercalated water molecules that exist in the layered structure. In particular, we observe that the doping stage of a MoS₂ FET strongly depends on the environment (air/vacuum). For the channel width scaling, the impact of edge states in three types of TMDs, metallic T_d-phase WTe₂ as well as semiconducting 2H-phase MoTe₂ and MoS₂ were explored, by patterning thin flakes into ribbons with varying channel widths. No obvious charge depletion at the edges is observed for any of these three materials, which is different from what has been observed in graphene nanoribbon devices. </div>

Improvement in the in vitro oxidative folding of disulfide-containing proteins, such as extracellular and pharmaceutically important proteins, is required. Traditional folding methods using small molecule aliphatic thiol and disulfide, such as glutathione (GSH) and glutathione disulfide (GSSG) are slow and low yielding. Small molecule aromatic thiols and disulfides show great potentiality because aromatic thiols have low pKa values, close to the thiol pKa of protein disulfide isomerase (PDI), higher nucleophilicity and good leaving group ability. Our studies showed that thiols with a positively charged group, quaternary ammonium salts (QAS), are better than thiols with negatively charged groups such as phosphonic acid and sulfonic acid for the folding of bovine pancreatic trypsin inhibitor (BPTI). An enhanced folding rate of BPTI was observed when the protein was folded with a redox buffer composed of a QAS thiol and its corresponding disulfide. Quaternary ammonium salt (QAS) thiols and their corresponding disulfides with longer alkyl side chains were synthesized. These QAS thiols and their corresponding disulfides are promising small molecule thiols and disulfides to fold reduced BPTI efficiently because these thiols are more hydrophobic and can enter the core of the protein. Conformational changes of disulfide-containing proteins during oxidative folding influence the folding pathway greatly. We performed the folding of BPTI using targeted molecular dynamics (TMD) simulation and investigated conformational changes along with the folding pathway. Applying a bias force to all atoms versus to only alpha carbons and the sulfur of cysteines showed different folding pathways. The formation of kinetic traps N' and N* was not observed during our simulation applying a bias force to all atoms of the starting structure. The final native conformation was obtained once the correct antiparallel β-sheets and subsequent Cys14-Cys38 distance were decreased to a bond distance level. When bias force was applied to only alpha carbons and the sulfur of cysteines, the distance between Cys14-Cys38 increased and decreased multiple times, a structure similar to the confirmation of N*, NSH were formed and native protein was ultimately obtained. We concluded that there could be multiple pathways of conformational folding which influence oxidative folding.

Inadequate financial allocation for road maintenance is a threat to the impaired rural highways in Atlantic Canada. The conventional means of pavement rehabilitation has been to place a hot mix asphalt concrete overlay on the existing worn out pavement which is only a short term adjustment. The purpose is to provide a smooth wearing surface at a low cost. This traditional way of pavement repair does not fix the damage embedded within the pavement structure. After a certain extent of time the cracks in the original pavement start to reflect to the smooth new wearing surface, causing deterioration on the overlay. The advanced approach which is becoming more popular is the application of Full Depth Reclamation (FDR). This technique helps to repair the extensively defective roads by pulverizing the flexible pavement along with a fraction of the underlying damaged base layer. Thus a damage free base layer can be obtained by stabilizing and recompacting the pulverized materials. FDR is a sustainable and an environmentally beneficial repair method as it re-uses the in-situ materials. FDR process has been used around the world for over 25 years yet confronts some difficulties regarding the fluctuation in the strength of materials in various projects. It is inferred that some of these difficulties are due to the variability and poor quality in the restored materials. The variability in the recycled base layer is a result of currently utilizing a retroactive depth control method to attain a specific blend of asphalt concrete to granular base for the pulverized materials. Two FDR projects applying two different pulverization control methods (conventional retroactive and GPR depth control methods) were analyzed to investigate the improvements in consistency of the restored materials by using Ground Penetrating Radar (GPR). A wide range of asphalt concrete/base layer blend ratio was detected in retroactive control section, while consistent blend ratio was maintained in GPR survey by mapping the variability in the depth of pavement and sub-dividing the test sections accordingly. A GPR controlled constant blend ratio during pulverization displayed improvements in consistency of materials, physical and mechanical properties and performance as anticipated. The materials obtained by using the conventional retroactive depth control method exhibited higher variability in grain size distribution, optimum moisture content, optimum density, California Bearing Ratio, resilient modulus and shear strength. All materials from both projects exhibited excessive air voids and inadequate fines content as the as-obtained particles acted as conglomerated particles and enough fines were not generated after the pulverization. It is recommended that efficient quality control, precise specifications and appropriate pulverization methods will provide more reliable and impressive FDR pavements. / This thesis contains research on unstabilized full depth reclaimed aggregates properties

The thesis deals with study of thin layers of transition metal dichalcogenides, especially of molybdenum disulfide. Nanostructures were fabricated on two-dimensional crystals of MoS2 and WSe2. Within followed analysis attention was paid to the photoluminescence properties. In the thesis transition metal dichalcogenides are reviewed and description of the modified process of preparation by micromechanical exfoliation is given.

The diploma thesis deals with dynamic analysis of cable-stayed steel pedestrian footbridge. The dynamic response of pedestrian-induced vibration was studied. The response of structure exeeded standard acceptance limit. Due to the effect of installed Tuned Mass Damper was studied. Motion equations of single and two degree of freedom model were solved in program MATLAB and the results were compared with numeric model in ANSYS.

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SyfteUndersöka påverkan av kronisk orofacial smärta och psykologiska faktorer på sömnkvalitet vid käkmuskelmyalgi.Material och metoderDenna retrospektiva studie omfattade 37 patienter (6 män, 31 kvinnor, medelålder: 49 år) med käkmuskelmyalgi. Sömnkvalitet (Pittsburgh Sleep Quality Index), smärtintensitet och smärtrelaterad funktionsnedsättning (Graded Chronic Pain Scale), depression (Patient Health Questionnaire-9), ångest (General Anxiety Disorder-7), stress (Perceived Stress Scale-10) och katastrofiering (Patient Catastrophizing Scale) undersöktes med varierade formulär. Diagnostic Criteria for Temporomandibular Disorders (DC/TMD) användes för att identifiera patienter med myalgi i käkmuskulatur.Resultat75% av patienterna rapporterade dålig sömnkvalitet, 73% rapporterade minst mild depressionsgrad, 54% rapporterade minst mild ångest, 59% rapporterade måttlig stressnivå och 38% rapporterade kliniskt relevant katastrofiering. Försämrad sömnkvalitet var relaterad till depression (rs = 0.45, n = 37, p = 0.008) ångest (rs = 0.46, n = 37, p = 0.007), stress (rs = 0.43, n = 37, p = 0.014) och katastrofiering (rs = 0.37, n = 37, p = 0.034). Multivariat logistisk regression visade att smärtintensitet, smartrelaterad funktionsnedsättning, depression, ångest, stress, katastrofiering och antal käkmuskler med refererad palpationssmärta förklarade dålig sömnkvalitet signifikant (p = 0.031).KonklusionSömnkvaliteten hos patienter med käkmuskelmyalgi påverkas i hög grad av kronisk smärtintensitet, smärtrelaterad funktionsnedsättning, antal käkmuskler med refererad palpationssmärta och depression samt ångest, stress och katastrofiering. / AimInvestigate the influence of chronic orofacial pain and psychological factors on sleep quality in patients with myalgia of the masticatory muscles.Material and methodsThis retrospective study included 37 patients (6 men, 31 women, mean age: 49 years) with masticatory muscle myalgia. Sleep quality (Pittsburgh Sleep Quality Index), pain intensity and pain-related disability (Graded Chronic Pain Scale), depression (Patient Health Questionnaire-9), anxiety (General Anxiety Disorder-7), stress (Perceived Stress Scale-10) and catastrophizing (Patient Catastrophizing Scale) were assessed by questionnaires. The Diagnostic Criteria for Temporomandibular Disorders (DC/TMD) were used to identify patients with myalgia.Results75% of the patients reported poor sleep quality, 73% reported at least mild depression degree, 54% reported at least mild degree of anxiety, 59% reported at least a moderate stress level and 38% reported a clinically relevant degree of catastrophizing. Impaired sleep quality was related to degree of depression (rs = 0.45, n = 37, p = 0.008), anxiety (rs = 0.46, n = 37, p = 0.007), stress (rs = 0.43, n = 37, p = 0.014) and catastrophizing (rs = 0.37, n = 37, p = 0.034). Multivariate logistic regression showed that characteristic pain intensity, degree of pain-related disability, depression, anxiety, stress, catastrophizing and number of masticatory muscle sites with referred pain significantly explained poor sleep quality (p = 0.031).ConclusionSleep quality in patients with masticatory myalgia is influenced by chronic pain intensity and related disability, number of masticatory muscle sites with referred pain as well as depression, anxiety, stress and catastrophizing.