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Quantum nondemolition measurements are made by back-action evasion obtained by a combination of a parametric oscillation and a conversion of polarizations. A polarization converter (14, 16, 17), such as a Faraday rotator, converts at substantially a single frequency between at least a portion of a signal polarization state and a detector polarization state. A parametric amplifier (11) having a gain G is coupled to the polarization converter (14, 16, 17).
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A pressurized breathable gas, preferably air, is supplied to the patient's airways with an interface including a mask and a flexible hose. A selected oscillation component or forced probing signal is applied or superposed on the pressurized breathable gas, preferably with a loudspeaker coupled to a frequency generator. Pressure and flow of the breathable gas in the interface are measured or sampled, preferably using pressure transducers and a pneumotachometer coupled to a personal computer, to obtain pressure and flow data characteristic of the patient's airway. The pressure and flow data are converted to the frequency domain using Fourier transform or cross-power spectrum techniques in the personal computer. A function of the processed pressure and flow data is obtained to determine an index of airway impedance or degree of airway obstruction.
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Second generation SFF techniques allow both composition and shape to be downloaded directly from a computer file so that 3D functionally graded materials (FGM) can be assembled. Methods for multi-material deposition are also needed in combinatorial research, colour management and pharmaceutical dosing. In this work, computer-controlled microfeeding systems using ultrasonic vibration of a capillary were built. A wide range of stable flow rate control and switching control were achieved in the acoustic vibration system, and uniform powder doses were obtained in the ultrasonic system. The experimental results show that the nozzle diameter, transmission fluid depth, waveforms, voltage amplitude, frequency and oscillation duration all influence the dose mass. Among these factors, the nozzle diameter, voltage amplitude and oscillation duration can be used to control the dose mass. Raster printing of patterns with various resolution and dot size are demonstrated.
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In this article, we investigate an innovative solid-state welding technique called Ultrasonic Consolidation (UC) that is being developed as a freeform process for the layered fabrication of aluminium tapes. UC involves the use of high frequency, low amplitude mechanical vibrations that induce combined static and oscillating shear forces to produce elastic-plastic deformation at the work-piece interface. This tends to break up and disperse aluminium oxide and permits atomic diffusion to occur. The work centres on material characterisation of aluminium tapes for aerospace and tooling applications. This paper will look at the mechanical properties of aluminum 3003 specimens prepared by UC using different control parameters that will lead to the determination of a general process window.
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The nitrile stretching oscillation has been widely used as a probe of local environment to study dynamics, folding, and electrostatics in proteins. A popular model for interpreting nitrile frequencies is the vibrational Stark effect (VSE), which allows one to interpret changes in vibrational energy in terms of changes in force along the nitrile bond. In principle, this allows for the site-specific, directional measurement of electric fields in a complex protein environment. However, the interpretation of these frequencies in terms of electric fields is complicated by the fact that hydrogen bonding to the nitrile probe is known to cause frequency shifts that are not described by the VSE. To address this concern, we have biosynthetically incorporated para-cyanophenylalanine (pCNF) probes into green fluorescent protein (GFP) near the intrinsic fluorophore, whose sensitivity to electric fields has been well characterized. We observed that the vibrational and electronic probes of electrostatic environment have similar spectroscopic responses to a series of amino acid mutations, and that the intrinsic sensitivity of GFP emission energy to the mutations was unperturbed by the presence of the pCNF probes. Additionally, we compared the measured Stark effect shifts to pK [subscript a] changes of the GFP fluorophore and saw that these two orthogonal measurements of electrostatic environment were in agreement, which further corroborates the analysis of VSE shifts of nitriles in terms of electric fields. These studies provide confidence in the ability of nitrile frequencies to report faithfully on electric fields, even in the background of direct hydrogen bonding to the probes. Finally, based on our analysis of electrostatic forces near the GFP fluorophore, we designed and characterized an interesting GFP mutant that can be photoactivated by near-UV light. We obtained preliminary evidence in the form of mass spectrometry and kinetic analysis that support a novel charge transfer mechanism for this photoconversion, which could lead to the design of fluorescent proteins with enhanced properties. In summary, we have developed GFP as a robust model system for understanding and manipulating the finely tuned relationship between protein structure and function.
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This thesis presents advanced design techniques for successive approximation register (SAR) analog-to-digital converters (ADCs), continuous-time ∆Σ ADCs, and single-slope (SS) ADCs in nano-scale CMOS technologies. (1) In high-speed SAR ADCs, metastability of the comparator limits the performance, which even results in the sparkle code errors. Proposed background calibration utilizing the comparator decision time detector removes the metastability-induced sparkle code errors by controlling the metastability detection window. At the same time, 1-bit resolution increase is gained from the proposed technique, which results in the fewer comparison cycles. Along with the relaxed requirement on the comparator, this cycle reduction helps to achieve the good power efficiency in high-speed SAR design. A prototype ADC in 40nm CMOS achieves 35.3dB SNDR and consumes 0.81mW while sampling at 700MS/s. (2) In the proposed continuous-time ∆Σ ADCs, conventional power-hungry opamp is replaced by voltage controlled oscillators (VCOs) that perform the data conversion in the phase domain instead of the voltage domain. In contrary to the opamp which is difficult to achieve good performance in the advanced CMOS process, VCOs have many advantages in the phase domain. To solve the nonlinear gain of VCOs, dual VCO-based integrator is used to suppress the dominant second-order distortion. To address the distortion from the DAC, a novel DAC calibration technique that both digitally senses and removes DAC mismatch errors is proposed. It has low hardware complexity by taking advantage of the intrinsic clocked level averaging (CLA) capability of dual-VCO-based integrator. It ensures high linearity regardless of the VCO center frequency. By lowering the VCO center frequency, power consumption is reduced. A prototype ADC designed in 130nm occupies an area of only 0.04mm² . It achieves 71dB SNDR over 1.7MHz bandwidth (BW) while sampling at 250MS/s and consuming only 0.9mW from a 1.2V power supply. The corresponding figure-of-merit (FOM) is 98 fJ/conversion-step. (3) A SS ADC has advantages of high linearity and a simple architecture. Thus, it is well suited for the column-parallel architecture for the CMOS image sensors. However, conversion speed is severely limited in high-bit resolution since more than 2 [superscript N] cycles are required for a N-bit resolution. To tackle this limitation, a two-step approach becomes popular. In this thesis, a two-step SAR/SS architecture is presented. In addition to reducing the conversion time, analog correlated double sampling (CDS) can cancel kT/C noise, which enables capacitor area reduction. A prototype ADC in 180nm CMOS occupies only 9.3µm x 830µm. It achieves 60.5dB SNR after CDS while sampling at 256kHz and consuming 91µW
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An innovative method for rapid prototyping (RP) of electronic circuits with components characteristic of typical electronics applications was demonstrated using an enhanced version of a previously developed hybrid stereolithography (SL) and direct write (DW) system, where an existing SL machine was integrated with a three-axis DW fluid dispensing system for combined arbitrary form electronic systems manufacturing. This paper presents initial efforts at embedding functional electronic circuits using the hybrid SL/DW system. A simple temperature-sensitive circuit was selected, which oscillated an LED at a frequency proportional to the temperature sensed by the thermistor. The circuit was designed to incorporate all the required electronic components within a 2.5” x 2” x 0.5” SL part. Electrical interconnects between electronic components were deposited on the SL part with a DW system using silver conductive ink lines. Several inks were deposited, cured, and tested on a variety of SL resin substrates, and the E 1660 ink (Ercon Inc, Wareham, MA) was selected due to its measured lowest average resistivity on the SL substrates. The finished circuit was compared with Printed Circuit Board (PCB) technology for functionality. The electronic components used here include a low voltage battery, LM 555 timer chip, resistors, a thermistor, capacitors, and Light Emitting Diodes (LEDs). This circuit was selected because it (1) represented a simple circuit combining many typically used electronic components and thus provided a useful demonstration for integrated electronic systems manufacturing applicable to a wide variety of devices, and (2) provided an indication of the parasitic resistances and capacitances introduced by the fabrication process due to its sensitivity to manufacturing variation. The hybrid technology can help achieve significant size reductions, enable systems integration in atypical forms, a natural resistance to reverse engineering and possibly increase maximum operating temperatures of electronic circuits as compared to the traditional PCB process. This research demonstrates the ability of the hybrid SL/DW technology for fabricating combined electronic systems for unique electronics applications in which arbitrary form is a requirement and traditional PCB technology cannot be used.
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