Fretting fatigue is a major concern in the design of engineering components that will be subjected to clamping pressures whilst operating in a vibrational environment. The type of loading environment generated in these applications is generally of a variable amplitude nature. Therefore it is important for engineers to understand how such loading affects the severity of fretting fatigue. In the absence of this understanding, engineering designers are left to apply simplistic plain fatigue life prediction rules, such as Miners linear damage law, to try to estimate the damage generated from a particular loading history. In order to try to establish a baseline for the understanding of fretting fatigue under variable amplitude loading, a structured series of CAL and V AL tests were designed and carried out. The aim of the CAL tests was to characterise the fretting fatigue test rig (designed by the author) so that an experimental foundation could be developed, upon which the fretting fatigue study was based. A structured investigation into the effects on fretting fatigue of applying various specifically designed loading histories was carried out and some very distinct relationships between the applied loading spectra and fretting fatigue life were found. For the application of overloads it was observed that overload size, overload application interval and the number of overloads in each application all had a sizeable effect on the severity of fretting. Two-level, three-level and five-level block loading tests were also investigated and numerous loading history dependent results were obtained. The applicability of Miners law to fretting fatigue was assessed. Combining Miners law with well-defined CAL stress-life results gave reasonable predictions for all of the V AL fretting fatigue tests carried out, with damage summations at failure ranging from 0.64 (non-conservative) to 3.19 (conservative). However, a more detailed investigation into the relationship between fretting fatigue lives and damage summations due to the individual loading levels highlighted that the assumption of linear damage may not be applicable to fretting fatigue, especially during crack initiation and early crack growth. A hypothesis was proposed to explain the fretting fatigue life and Miner damage results observed for the different loading spectra, and reasonable success was obtained for tests where the Miners law proved conservative (in 27 of 36 tests), although the hypothesis was not able to explain the non-conservative results obtained in the other nine tests.

In this paper, we investigate the optimal design of optically gain-clamped (GC) erbium-doped fiber amplifier (EDFA). Three configurations under discussion, the first uses two optical circulators (OC), one optical band pass filter (OBPF), and one variable optical attenuator (VOA), to form ring cavity. Such ring cavity can regulate itself: when the channel numbers increase, the amounts of optical feedback decrease; contrarily, when the channel numbers decrease, the amounts of optical feedback increase. So it has the gain-clamped ability. The second employs one or double fiber Bragg grating (FBG) to reflect the residual Amplified Spontaneous Emission (ASE) for regulating the signal gain, such configurations have the same self-regulation as before. The choice of center wavelength and bandwidth of FBG can control the signal gain to reach the optimal gain and fairly low noise figure (NF). The third configuration is similar to the first; the difference is that the third with figure-8 cavity, which uses a common OBPF and VOA, can regulate the gain of C- and L-bands at the same time. The choice of OBPF is just located within the dead-zone between the C- and L-bands, where no WDM channels can be transmitted. If we choose suitable loop attenuation, we can get an equal signal gain of C- and L-bands¡¦ channels.

The aim of this thesis is to design a clamping unit with mechanical multiplier. Unit will serve as a technological clamping element in the technical equipment. My task was to select the method of construction and design driving main unit for grip jaw. I chose a solution with a mechanical multiplier. The frame unit is made up of fixed and sliding clamping jaw and is self. Unit is designed as a built module. The entire structure must be designed to meet the initial parameters specified in the award of thesis. The main parameters include clamping strength of 80kN, the extent of working stroke 15 mm and the size of a scroll, which is 250 mm. They are also listed in the award size constraints: the length, width, height dimensions and the coupling unit.

Recently, the long-wavelength band (L-band, 1570-1600 nm) erbium-doped fiber amplifiers (EDFAs) has received much attention. By combining the gain bandwidth of a conventional C-band EDFA and L-band EDFA in parallel, the available gain bandwidth can be increased by a factor of two. The change in the input power and the number of channels leads to the variation of the channel output power, which, in turn, changes the gain spectrum and flatness. To cope with this problem, the gain-clamped (GC) technique has been proposed. The gain-clamping techniques have been extensively explored for C-band EDFAs, but fewer for L-band EDFAs. In this thesis, we experimentally investigate an optically gain-clamped L-band EDFA with different lasing lights (1568 nm and 1600 nm) and different loop attenuation. The characteristics of such L-band GC-EDFAs measured in a simulated add-drop operation are examined and compared. We find that the 1568-nm lasing light with 0-dB loop attenuation is the better selection for L-band GC-EDFA to offer good channel gain (19.4 dB) and satisfied noise figure characteristics. Compared to the gain variation observed for GC-EDFA with an open loop, the GC-EDFA was effective in reducing the total gain variation of 17 dB and increasing the dynamic range of 25 dB.

No description available.

D-Aspartate (D-Asp) is an endogenous compound found in the central nervous system (CNS) of a variety of organisms. Despite its prevalence, however, relatively little understood of its physiological role. The prevailing theory is that D-Asp is an alternate agonist of N-methyl-D-aspartate receptor (NMDAR) channels. The goal of this work was to characterize the currents activated by D-Asp in neurons Aplysia californica, focusing on cells of the buccal S cluster (BSC). First, a general electrophysiological characterization was carried out, examining ion permeability, agonist dose-response, and the kinetics of activation, inactivation, and desensitization. D-Asp activated non-specific cation currents characterized by permeability to Na+ and K+. D-Asp-induced currents shared similar current-voltage relationships and time courses of activation and inactivation with L-glutamate (L-Glu)-induced currents. D-Asp currents, however, were subject to prolonged desensitization. Additionally, D-Asp activated currents independently of L-Glu, the known agonist of NMDAR channels, suggesting a non-NMDAR-dependent role of D-Asp. Next, select antagonists were used in an effort to pharmacologically characterize D-Asp receptor channels. These experiments suggested that D-Asp whole cell currents may be characterized by activation of multiple receptor sites, including NMDARS, excitatory amino acid transporters (EAATs), and a putative non-L-Glu D-Asp receptor. Furthermore, bath-applied D-Asp attenuated L-Glu-activated currents. Finally, D-Asp currents were compared to those evoked by acetylcholine (ACh) and serotonin (5-HT) in BSC cells. Results suggested that D-Asp activated receptor channels independently of ACh and 5-HT. Ten minute bath application of 5-HT was found to potentiate D-Asp current responses, likely through activation of a protein kinase C (PKC)-dependent mechanism, suggesting that D-Asp induced currents may be subject to synaptic plasticity associated with learning. While the identity of the putative D-Asp receptor remains elusive, the current work has advanced our understanding of the role D-Asp may play in the nervous system. These results should provide the groundwork for future studies aimed at identifying this unknown receptor channel, as well as investigation of the potential relationship of D-Asp receptor modulation to learning and memory in Aplysia, which may have relevance in higher organisms.

<p> A set of scales was created, the "Modified Conibear Scales" which can be used as a basis of comparison to rate the performance of other traps in the areas of impact energy, closing time and clamping force. Further, a detailed set of secondary non quantitative characteristics was presented.</p> <p> Using the above information, several promising traps were rated in order to assess these scales, give some immediate results and indicate promising traps or trap features. Further work in the field was facilitated by providing a detailed experimental procedure, complete lists of data and a calibrated trap for animal research.</p> / Thesis / Master of Engineering (MEngr)

Patch clamping is considered the gold standard in measuring the bioelectrical activity of a cell. It is used to detect and measure ion transport through ion channels located throughout a cell membrane. Ion movement is crucial to cell viability and cell-to-cell communication. Pharmaceutical companies increasingly target ion channels because of their significance in disease and to help design better targeted drugs. However, the traditional method of patch clamping is cumbersome and is being replaced by planar high throughput screening (HTS) systems. These systems are reaching their limits due to materials and cost of processing; cell handling methods and small varieties of applicable cell types are also issues to be addressed. In this work, the core components of a new kind of planar patch clamping device have been designed and developed, after analysis of currently available HTS systems. This design approaches patch clamping using polymers to overcome some of the limitations in current systems, specifically cell handling and positioning, by using a simple modification technique to provide distinct attractive areas for cell binding. This uniquely allows the culture of both single cells and cell networks to increase the range of cell types that can be measured and circumvents challenges from using suction to pull cells onto measurement holes. The components of the design are a 10 x 10 array of small holes drilled in a polymer then aligned modifications for precise cell placement are added and a planar electrode array for individual addressing of each cell. A study of methods to produce a leak-tight seal required between microfluidic chambers was done. Cell adhesion parameters for the modification techniques were established. The principle viability of this approach was confirmed using the modification technique to culture cells over holes and measure their resistance using a rig developed for this work.

The first topic of this thesis is a voltage boost level clamping circuit for a flash memory which utilizes an implicit feedback loop as well as MOS transistors with different threshold voltages. The proposed design can be added to charge pumps to stabilize the output voltage. The unwanted output voltage spikes introduced by the linear pumping ratio are prevented. Not only are possible damages to memory cores avoided, the power disspation is reduced in contrast with prior regulator methods. The second topic is a switch-current 3-bit CMOS wideband random signal generator, which utilizes a digital normalizer to flatten the distribution of the probability in the entire range of B parameter. The ¡§colored¡¨ random numbers problem in prior designs is resolved. In addition, the coefficients of the proposed design are dynamically adjustable.

The target of Master Thesis with theme „The innovation of production technologie of pressure reservoir“, is a description of manufacturing technologie currently in use and design a new technologie. Part of new development of technologie is a selection of suitable spectrum of rails (pressure reservoir), design invention of appropriate machine loading system and clamping fixture placed into machine. Also the comparison of technologckl and economical parameters of proposed designed technologies and technologie currently in use - the final evaluation included.