Reinforced concrete slab-column structures are widely used because of their practicality. However, this type of structures can be subject to punching-shear failure in the slab-column connections. Without shear reinforcement, the slab-column connection can undergo brittle punching failure, especially when the structure is subject to lateral loading in seismic zones. The shear bolts are a new type of transverse reinforcement developed for retrofit of existing structures against punching. This research focuses on how the shear bolts can improve the punching-shear capacity and ductility of the existing slab-column connections under vertical service and lateral seismic loads. A set of nine full-scale reinforced concrete slab-column connection specimens were tested under vertical service and cyclic loads. The vertical (gravity) load for each specimen was kept at a constant value throughout the testing. The cyclic lateral drift with increasing intensity was applied to the columns. The specimens were different in number of bolts, concrete strength, number of openings, and level of gravity punching load. Strains in flexural rebars in the slabs, crack widths, lateral loads, and displacements were obtained. The peak lateral load (moment) and its corresponding drift ratio, connection stiffness, crack width, and ductility were compared among different specimens. The testing results show that shear bolts can increase lateral peak load resisting capacity, lateral drift capacity at peak load, and ductility of the slab-column connections. Shear bolts also change the failure mode of the slab-column connections and increase the energy dissipation capacity. The thesis includes also research on the development of guidelines for shear bolt design for concrete slab retrofitting, including the punching shear design method of concrete slab (with shear bolts), dimensions of bolts, spacing, and influence of bolt layout patterns. Suggestions are given for construction of retrofitting method using shear bolts. Recommendations are also presented for future research.

Intervertebral disc herniations have been indicated as a possible injury development pathway due to occupational vibration exposures in seated postures through epidemiological investigations. Little experimental evidence exists to corroborate the strong epidemiological link between intervertebral disc herniations and vibration exposures using basic scientific approaches. The purpose of the current investigation was to provide some basic experimental evidence of the epidemiological link between intervertebral herniation and exposure to vibration. Partial intervertebral disc herniations were created in in-vitro porcine functional spinal units using a herniation protocol of repetitive flexion/extension motions under modest compressive forces. After herniation initiation, functional spinal units were exposed to 8 different vibration and postural constraint loading protocols consisting of two postural conditions (full flexion and neutral) and 4 vibration loading conditions (whole-body vibration, shock loading, static compressive loads, and whole-body vibration in addition to shock loading) to assess the effects of vibration and posture on functional spinal unit damage progression. There were three main outcome variables used to quantify damage progression; average stiffness changes, herniation distance progression (distance of tracking changes), and specimen height changes, while cumulative loading factors were considered. Additionally the concordance between two types of contrast enhanced medical imaging (Computed Tomography and discograms) was qualified to a dissection ‘gold standard’, and an attempt was made to classify disc damage progression via three categorical variables. Concordance to a dissection ‘gold standard’ was higher for the Computed Tomography medical imaging type that for the Discograms. The categorical criteria used to qualify disc damage progression were insufficiently sensitive to detect damage progressions illustrated through dissection and medical imaging techniques. The partial herniation loading protocol was quantified to be more damaging overall to the functional spinal units compared to the vibration and postural constraint loading protocols. However, the vibration and postural constraint loading protocols provided sufficient mechanical insult to the functional spinal units to progress damage to the intervertebral discs. Vibration loading exposures were found to alter specimen height changes and distance of tracking changes, however posture had no significant effects on these variables. Neither posture nor vibration loading had any meaningful significant effects on average stiffness changes.

Despite years of research, the role that hypovolemia plays in orthostatic intolerance after head down bed rest (BR) and spaceflight remains unclear. Additionally, the efficacy of oral saline countermeasures, employed in an attempt to restore plasma volume (PV) after BR is questionable. Several previous studies have suggested that a new homeostatic set point is achieved in space or during BR, making attempts to restore PV temporary at best. We tested the hypotheses that one day of BR would induce a transient increase in PV followed by hypovolemia and new hormonal balance; that a salt tablet and water fluid loading (FL) countermeasure would be ineffective in restoring PV; and also that the FL would not attenuate the exaggerated hormonal responses to orthostatic stress that are expected after 28hr of BR. Plasma volume, serum sodium and osmolarity, and plasma ANP, AVP, renin, angiotensin II, aldosterone, and catecholamines were measured in nine male subjects undergoing 5 different protocols (28hr Bed Rest without Fluid Loading = 28NFL, 28hr Bed Rest with Fluid Loading = 28FL, 4hr Seated Control = 4NFLS, 4hr Seated Control with Fluid Loading = 4FLS, and 4hr Bed Rest = 4BR) in a randomized repeated measures design. The FL countermeasure was 15 ml/kg of body weight of water with 1g of NaCl per 125ml of water. Orthostatic testing by lower body negative pressure (LBNP) was performed before and after all protocols. In agreement with our first hypothesis, we observed transient reductions in renin, angiotensin II, and aldosterone, which after 25.5hr were restored to baseline, slightly augmented, and suppressed, respectively. Also after 25.5hr, PV was reduced in the 28hr BR protocols and was not restored in 28FL; however, the FL protocol increased PV during 4FLS. We additionally observed augmented renin and aldosterone responses, as well as generally elevated angiotensin II after 28NFL, but not after 28FL or any of the 4hr protocols. Furthermore, no changes in plasma norepinephrine responses to LBNP were documented from Pre-Post test in any protocol. Our results indicate that: 1) PV is reduced after short term BR and is not restored by an oral FL; 2) renin-angiotensin-aldosterone system (RAAS) responses to orthostatic stress are augmented after 28hr of BR and the amplified response can be abrogated by FL; and 3) plasma norepinephrine responses during orthostatic stress are not affected by BR or FL, suggesting that RAAS activity may be modulated by FL independently of sympathetic activity and PV during orthostasis after bed rest.

Parkinson's disease (PD) is a neuro-degenerative chronic disorder with cardinal signs of bradykinesia, resting tremor, rigidity, and postural abnormality/instability. Tremor, which is a manifestation of both normal and abnormal activities in the nervous system, can be described as an involuntary and periodic oscillation of any limb. Such an oscillation with a small amplitude, which is barely visible to the naked eye, is present in healthy people. This is called a physiological tremor and is asymptomatic. This tremor is believed to be the result of at least two distinct oscillations. A passive mechanical oscillation that is produced by the irregularities of motor unit firing, and by blood ejection during cardiac systole. The frequency and amplitude of these oscillations are dependent on the mechanical properties of the limb including joint stiffness and limb inertia. There is another component of oscillation that does not respond to elastic or inertial loading, which is called the central component, and is believed to arise from an unknown oscillating neuronal network within the central nervous system. Unlike physiological tremor, pathological tremors are symptomatic and can impair motor performance. Parkinson's disease (PD) tremor is generally manifested at rest, but also occurs during posture or motion. Classical PD rest tremor is known to be a central tremor of 4-6 Hz and peripheral origins have only a minimal role. However, whether or not the same central mechanism remains active during action tremor (including posture and movement) should yet be answered. Contrary to PD rest tremor, reported results on action tremor in the literature are diverse; and the reason for the changes in tremor characteristics in situations other than rest, or generally during muscle activation, is not fully understood. The lack of generality in the results of studies on action tremor, makes the efforts of treatment difficult, and is a barrier for mechanical/engineering approaches of suppressing this tremor. To investigate the role of mechanisms other than classic rest tremor, and possible sub-categories of tremulous PD in yielding diverse results, this study was conducted on twenty PD patients and fourteen healthy age-matched (on average) controls. To evaluate the possible contribution of (enhanced) physiological tremor, the study considered the effect of loading on postural hand tremor in a complete range of 0-100% MVC (Maximum Voluntary Contraction). The study looked at two measures of tremor amplitude and one measure of tremor frequency, and focused on two frequency bands of classic-rest (3.5-6.5 Hz) and physiological (7.5-16.5 Hz) tremors. The study revealed that PD tremor was not uniformly distributed in the three dimensional space, and then focused on the investigation of tremor in the dominant axis, which was the same as direction of loading. It also revealed that dopaminergic medication could significantly affect tremor components only in PD band, compared to the components in the physiological band. The study was an extension to previous studies and yielded similar results for the previously reported range of loading. However, with the extended range of loading, it revealed novel results particularly after separating PD patients into sub-groups. It was hypothesized that the coexistence of physiological mechanism, and considerable difference between sub-types of tremulous PD patients, are responsible for most of the diversity in the previously reported studies. This study showed that for clearer results the sub-groups are inevitable, and that automatic classification (clustering) provided the most separable sub-groups. These sub-groups had distinct trends of load effect on tremor amplitude and frequency. No matter which categorization method was used, at least one sub-group exhibited significantly higher tremor energy compared to the healthy participants not only in the PD band, but also in the physiological band. This meant that, for some sub-groups of PD, the physiological tremor is a very important mechanism and not the same as that of healthy people. The coexistence hypothesis was also affirmed by examining tremor spectrums' peak frequency and magnitude in the two separate bands. The necessity of the separation of tremulous PD patients into sub-groups, and the coexistence of physiological and classic PD tremor mechanisms for some of them are the factor that should be considered in the design of a suppressing device and also in the proposed treatment of action tremor in this population.

The work in this thesis is concerned with the mechanics of the initiation and growth of small fatigue cracks from notches under service load histories. Fatigue life estimates for components subjected to variable amplitude service loading are usually based on the same constant amplitude strain-life data used for constant amplitude fatigue life predictions. The resulting fatigue life estimates although they are accurate for constant amplitude fatigue, are always non conservative for variable amplitude load histories. Similarly fatigue life predictions based on small crack growth calculations for cracks growing from flaws in notches are non conservative when constant amplitude crack growth data are used. These non conservative predictions have, in both cases, been shown to be due to severe reductions in fatigue crack closure arising from large (overload or underload) cycles in a typical service load history. Smaller load cycles following a large near yield stress overload or underload cycle experience a much lower crack opening stress than that experienced by the same cycles in the reference constant amplitude fatigue tests used to produce design data. This reduced crack opening stress results in the crack remaining open for a larger fraction of the stress-strain cycle and thus an increase in the effective portion of the stress-strain cycle. The effective strain range is increased and the fatigue damage for the small cycles is greater than that calculated resulting in a non conservative fatigue life prediction. Previous work at Waterloo introduced parameters based on effective strain-life fatigue data and effective stress intensity versus crack growth rate data. Fatigue life calculations using these parameters combined with experimentally derived crack opening stress estimates give accurate fatigue life predictions for notched components subjected to variable amplitude service load histories. Information concerning steady state crack closure stresses, effective strain-life data, and effective stress intensity versus small crack growth rate data, are all obtained from relatively simple and inexpensive fatigue tests of smooth specimens in which periodic underloads are inserted into an otherwise constant amplitude load history. The data required to calibrate a variable amplitude fatigue crack closure model however, come from time consuming measurements of the return of crack closure levels for small cracks to a steady state level following an underload (large cracks for which crack closure measurements are easier to make cannot be used because at the high stress levels in notches under service loads a test specimen used would fracture). For low and moderately high hardness levels in metals crack growth and crack opening stress measurements have been made using a 900x optical microscope for the small crack length at which a test specimen can resist the high stress levels encountered when small cracks grow from notches. For very hard metals the crack sizes may be so small that the measurements must be made using a confocal scanning laser microscope. In this case the specimen must be removed from the test machine for each measurement and the time to acquire data is only practical for an extended research project. The parameters for the crack closure model relating to steady state crack closure levels vary with material cyclic deformation resistance which in turn increases with hardness. One previous investigation found that the steady state crack opening level was lower and the recovery to a steady state crack opening stress level after an underload was more rapid for a hard than for a soft metal. This observation can be explained by the dependence of the crack tip plastic zone size that determines crack tip deformation and closure level on metal hardness and yield strength. Further information regarding this hypothesis has been obtained in this thesis by testing three different steels of varying hardness levels (6 HRC, 35 HRC, and 60 HRC) including a very hard carburized steel having a hardness level (60 HRC) for which no crack opening stress data for small cracks had yet been obtained. This thesis introduced a new test procedure for obtaining data on the return of crack opening stress to a steady state level following an underload. Smooth specimens were tested under load histories with intermittent underload cycles. The frequency of occurrence of the underloads was varied and the changes in fatigue life observed. The changes in damage per block (the block consisted of an underload cycle followed by intermittent small cycles) were used to determine the value of the closure model parameter governing the recovery of the crack opening stress to its steady state level. Concurrent tests were carried out in which the crack opening stress recovery was measured directly on crack growth specimens using optical microscope measurements. These tests on metals ranging in hardness from soft to very hard were used to assess whether the new technique would produce good data for crack opening stress changes after underloads for all hardness levels. The results were also used to correlate crack closure model parameters with mechanical properties. This together with the steady state crack opening stress, effective strain-life data and the effective intensity versus crack growth rate data obtained from smooth specimen tests devised by previous researchers provided all the data required to calibrate the two models proposed in this investigation to perform strain-life and small crack growth fatigue analysis.

Articular cartilage functions to maintain joint mobility. The loss of healthy, functional articular cartilage due to osteoarthritis or injury can severely compromise quality of life. To address this issue, cartilage tissue engineering approaches are currently in development. Bone marrow-derived mesenchymal progenitor cells (MPCs) hold much promise as an alternative cell source for cartilage tissue engineering. While previous studies have established that MPCs from humans and multiple other species undergo in vitro chondrogenic differentiation, additional research is needed to define conditions that will enhance MPC differentiation, increase matrix production by differentiating cultures, and support development of functional tissue-engineered cartilage constructs. Mechanical loading may be an important factor regulating chondrogenic differentiation of MPCs and cartilage matrix formation by chondrogenic MPCs. This thesis work evaluated the influence of oscillatory unconfined compressive mechanical loading on in vitro MPC chondrogenic activity and biosynthesis within hydrogel suspension. Loading was conducted using MPCs cultured in media supplements supporting chondrogenic differentiation. Possible interactions between the number of days in chondrogenic media preceding loading initiation and the ability of the MPC culture to respond to mechanical stimulation were explored in two different loading studies. The first loading study investigated the effects of 3 hour periods of daily oscillatory mechanical stimulation on subsequent chondrogenic activity, where chondrogenic activity represented an assessment of cartilage matrix production by differentiating MPCs. This study found that oscillatory compression of MPCs initiated during the first seven days of culture did not enhance chondrogenic activity above the level supported by media supplements alone. The second loading study evaluated changes in biosynthesis during a single 20 hour period of oscillatory mechanical stimulation to assess mechanoresponsiveness of the MPC cultures. This study found that MPCs modulated proteoglycan and protein synthesis in a culture time-dependent and frequency-dependent manner upon application of oscillatory compression. Together the two loading studies provide an assessment of dynamic compressive mechanical loading influences on MPC cultures undergoing chondrogenic differentiation. The information gained through in vitro studies of differentiating MPC cultures will increase basic knowledge about progenitor cells and may also prove valuable in guiding the future development of cartilage tissue engineering approaches.

The failure behavior of collagenous soft tissues is important for clinical problems of plaque rupture and trauma. Cyclic tests require high frequencies that may affect the strength properties of the soft tissues. Experimental results of mechanical response of blood vessels to physiologic loads can be used to model and predict plaque rupture and direct medical therapy or surgical intervention. The goal of the study is to measure the mechanical failure properties of arteries to determine if they are strain rate and cycle dependant and to measure the progressive damage of arteries with time dependent loading. Ring specimens of porcine carotid arteries were preconditioned and then pulled to failure. In all cases, the intima broke first. Ultimate stress increased as a weak function of increasing strain rates. The ultimate stress at 100 mm/s was 4.54 MPa, greater than the 3.26 MPa at 0.1 mm/s. Strain rates between 1 and 100 mm/s correspond to a cyclic frequency of 0.5 Hz to 5 Hz for fatigue testing. In contrast, ultimate strain in arteries was independent of strain rate over the range tested. The creep tests showed a logarithmic relationship between stress magnitude and stress duration for this soft tissue. The creep testing indicates that damage is accumulating above certain threshold stress levels. The values of ultimate strength showed a 35% increase after 10,000 cycling loading. In contrast, the ultimate strain had a 13% decrease after cycling and the difference was statistically significant with p=0.018. The testing results showed that there were no significant differences on strength among fresh arteries and arteries stored at 5¡ã C for up to two weeks. The test results may be useful for developing a mathematical model to predict the behavior of arterial soft tissues and may be extended to estimate fracture and fatigue in the atherosclerotic plaque cap.

Because of the shortage of domestic energy resources in Taiwan, more than 97% of the energy has to be imported. The energy price has been increased dramatically during recent years due to the limited supply of conventional primary fossil energy resources. With the economic development and upgrade of people living standard, the electricity power consumption is increased significantly. To solve the problem, different strategies of energy conservation and CO2 emission reduction have been promoted by government to reduce that the peak loading growth and achieve better usage of electricity with more effective load management. This thesis proposes a digital smart meter which integrates the energy metering IC, microprocessor and hybrid communication schemes (Power Line Carrier/ZigBee/RS-485). The load control module and communication module are included in the smart meter to support various application functions. The embedded power management system (PMS) is also proposed to integrate with the smart meter to perform the demand response according to the real-time pricing and load management for residential and commercial customers. The master station can supervise the real-time power consumption of various load components to analyze the power consumption model of customers served and execute the demand load control. The actual demonstration system of embedded PMS has been set up to verify the function of energy management so that the customers have better understanding of power consumption by each appliance. In the future, the implementation of intelligent load control with an emergency load shedding of capability can help utility companies to achieve virtual power generation to enhance the power systems reliability. The customers may also reduce the electricity charge by executing demand response function, which disconnects the electricity service for non essential loads for either system emergency or high electricity peak pricing

This study aims to design a Shunt Semi-Active Power Factor Correction Circuits , which can be applied to high power circuit by low switching frequency. The designed circuit can avoid power loss working with high switching frequency when using the method of active power factor correction .The experimental configuration based on DSP is applied to a compressor of air conditioner with varied load. The simulation check the developed circuit using Ispice . Both of the experimental and simulation results have guaranteed the derived configuration reach the expected goals.

In oil and gas field operations, the dynamic interactions between reservoir and wellbore cannot be ignored, especially during transient flow in the near-wellbore region. As gas hydrocarbons are produced from underground reservoirs to the surface, liquids can come from condensate dropout, water break-through from the reservoir, or vapor condensation in the wellbore. In all three cases, the higher density liquid needs to be transported to the surface by the gas. If the gas phase does not provide sufficient energy to lift the liquid out of the well, the liquid will accumulate in the wellbore. The accumulation of liquid will impose an additional backpressure on the formation that can significantly affect the productivity of the well. The additional backpressure appears to result in a "U-shaped" pressure distribution along the radius in the near-wellbore region that explains the physics of the backflow scenario. However, current modeling approaches cannot capture this U-shaped pressure distribution, and the conventional pressure profile cannot explain the physics of the reinjection. In particular, current steady-state models to predict the arrival of liquid loading, diagnose its impact on production, and screen remedial options are inadequate, including Turner's criterion and Nodal Analysis. However, the dynamic interactions between the reservoir and the wellbore present a fully transient scenario, therefore none of the above solutions captures the complexity of flow transients associated with liquid loading in gas wells. The most satisfactory solution would be to couple a transient reservoir model to a transient well model, which will provide reliable predictive models to link the well dynamics with the intermittent response of a reservoir that is typical of liquid loading in gas wells. The modeling work presented here can be applied to investigate liquid loading mechanisms, and evaluate any other situation where the transient flow behavior of the near-wellbore region of the reservoir cannot be ignored, including system start-up and shut-down.