Design and Performance of a 1 Meter Scale Horizontal Axis Wind Turbine Model

A research wind turbine of one-meter diameter was designed for the use in the UNH Flow Physics Facility (FPF), a large flow physics quality boundary layer wind tunnel. The turbine design was carried out as an aero-servo model of the NREL 5MW reference turbine, with some modifications. The turbine is used to obtain data for multiscale wake model verification and validation, including wake data over long distances downstream. Blockage in the FPF test section is 4.8% based on rotor swept area. The rotor was designed using blade element momentum theory based on the S801 airfoil. The optimal blade chord was scaled by 1.35 and 1.7 to raise the chord-based Reynolds number. This was done to achieve Reynolds number independent performance. Also, the blade pitch angle can be precisely adjusted. The turbine is designed to actively control tip speed ratio, as well as record torque, rotor rotational velocity, and thrust. The tip speed ratio control is achieved with a Parker Hannifin BE344J series servo motor and Compax3 drive. A Futek LSB302 load cell is used in a single axis force balance to record thrust and a Futek TRS605 rotary torque transducer is used to record torque and rotational velocity. A National Instruments USB6211 data acquisition board and custom LabVIEW machine interface was used to manage the signals and implement the control logic. Turbine performance was examined in the free stream. Reynolds number independent performance was shown above wind speeds above 7.5 m/s. Performance of the turbine was characterized, and maximum performance was shown at λ=6.1 with C_p=0.35 and C_T=1.05. The effect blade pitch angle was also examined, and it was shown that the peak turbine performance occurs at a blade pitch angle of zero degrees

The reduction of broadband crosstalk interference between multiple conductors in a backplane interconnect and its performance impact on gigabit digital communication signals

Crosstalk interference from signal transmission between transmission line conductors limits channel throughput as amplitude distortion in an experimental backplane connector. Shared return conductor microstrip connectors arranged in stacks have resonant frequencies that are determined largely by cavity dimensions of the return conductor geometries. If an input waveform to the connector excites these resonant frequencies, the resonant energy will couple to other signal conductors in the connector and will result in crosstalk interference. Lossy materials can be used to reduce the resonant crosstalk interference in connectors. Quasi-conductor and magnetic absorber materials were used to reduce the resonant crosstalk in an experimental connector. Full-wave computer simulation was used to calculate connector S-parameters and was compared with measurement. Empirical equations were developed to relate experimental S-parameters of connector lossy material configurations with system bit-error-rate, channel Q, and eye pattern height at the data rate of 10.6Gbps

A body area network for wearable health monitoring : conductive fabric garment utilizing DC-power-line carrier communication

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2007.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.Includes bibliographical references (p. 112-116).Wearable computing applications are becoming increasingly present in our lives. Of the many wearable computing applications, wearable health monitoring may have the most potential to make a lasting positive impact. The ability to remotely monitor physiological signals such as respiration, motion, and temperature has benefits for populations such as elderly citizens, fitness professionals, and soldiers in the battlefield. To fully integrate wearable networks into a user's daily life, these systems must be minimally invasive and minimally intrusive. At the same time, such wearable networks require multiple sensors and electronic components to be mounted on the body. Unfortunately, typical off-the-shelf components of this nature are heavy, bulky, and don't integrate well with the human form. Thus, it is critical to figure out how best to minimize the physical and mental burden that these systems place on the user. To address these problems, we propose a new method of designing wearable health monitoring networks by combining electrically conductive fabrics and power-line communication technology. Electrically conductive fabrics are useful in that they feel and behave like normally worn clothing but also have the ability to transmit data and power.(cont.) To fully exploit the conductive fabric as a transmission medium, we also use power-line communication technology. Power-line communication allows for simultaneous power and data transmission over a shared medium. The use of these two technologies will allow us to significantly reduce the amount of metal cabling on the body and to reduce overall system bulk and weight. With this project, we design the DC-PLC system that will act as the physical layer of the architecture. Next, we construct a prototype body area network, and derive analytical models for predicting garment electrostatic and electro-dynamic properties using Maxwell's equations, and verify using empirical data and finite-element analysis. Finally, we will determine relevant rules and guidelines for the design and construction of such garments.by Eric R. Wade.Ph.D

Scanning Tunneling Microscopy at milliKelvin Temperatures: Design and Construction

This dissertation reports on work toward the realization of a state-of-the-art scanning tunneling microscopy and spectroscopy facility operating at milliKelvin temperatures in a dilution refrigerator. Difficulties that have been experienced in prior efforts in this area are identified. Relevant issues in heat transport and in the thermalization and electrical filtering of wiring are examined, and results are applied to the design of the system. The design, installation and characterization of the pumps, plumbing and mechanical vibration isolation, and the design and installation of wiring and fabrication and characterization of electrical filters are described

Emerging materials for superconducting nanowire photon counting arrays

Superconducting nanowire single-photon detectors (SNSPDs) are the leading technology for low noise, high efficiency infrared single-photon detection. The basic SNSPD consists of a nanowire patterned in an ultrathin superconducting thin film, which is cooled below its critical temperature and biased close to its critical current. The absorption of a single-photon creates a resistive region, triggering a fast output voltage pulse which can be readily amplified and registered. The excellent performance of SNSPDs at near-infrared and telecommunications wavelengths has led to their adoption in important applications such as quantum secure communications, single-photon spectroscopy and single-photon LIDAR. A clear challenge for the SNSPD community is to extend the spectral range of SNSPDs into the mid infrared, and to improve material uniformity to enable the realization of large area arrays for multimode or free space coupling. The aim of this work is to evaluate potential materials for next generation mid-infrared SNSPD arrays. In this work, thin films of polycrystalline NbN and amorphous MoSi have been optimized to test the uniformity of a multipixel array configuration composed of 8 nanowire meander structures covering 10 um x 10 um area, 100 nm width and 50% filling factor. The 8-pixels SNSPD arrays have been patterned on 8 nm thickness NbN grown on high resistivity silicon (HR Si) substrate at room temperature and at 800 °C exhibiting respectively 4.4 K and 7.3 K as mean critical temperature across the pixels. The 8- pixels SNSPD array patterned on 8 nm thickness MoSi cooling the HR Si substrate to -180 °C has exhibited a mean critical temperature of 3.2 K across the pixels. Optical properties have been measured by an attenuated 1550 nm laser diode source delivered by single mode optical fibre at a controlled distance from the chip in order to broadly illuminate the array. The optical properties have been studied only for the 8 nm thickness NbN SNSPD array grown at room temperature has demonstrated uniform optical properties across pixels exhibiting similar saturation of the internal efficiency over a large bias, similar dark count rate and similar timing jitter (about 137 ps) across pixels. In the single photon regime at 1550 nm, pixels 4 and 6 of the 8 nm thickness NbN SNSPD array exhibit 28.4% and 4.7% pixel detection efficiency as measured at the bias current 95% of their respective critical current at 2.2 K

High efficacy extremely low frequency (ELF) pulsed electromagnetic field (PEMF) device for wound healing promotion

This research project successfully presents and discusses the design and construction of an extremely low frequency (ELF) PEMF device built on the basis of a Two-Axis (2-Axis) Helmholtz coil system (HCS) that is capable of producing a uniform time varying magnetic field in the frequency range of 2-500Hz and magnetic induction (magnetic flux density) of 0.5mT - 2.5mT. A custom software program was written in order to systematically analyze the induced magnetic field distribution and its region of uniformity within 10%, 1% and 0.1% of the center field, prior to commencing experimentation with the selected biological model systems. The applications of the developed ELF PEMF exposure device have been investigated in terms of the experimental evaluation of ELF PEMF irradiation on protein, i.e. Collagenase enzyme, and gram-positive and gram- negative bacterial cultures of Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) respectively. Through this study it was experimentally proved that it is possible to optimize ELF PEMF parameters (frequency, f, and magnetic flux density, B) of the applied irradiation which can modulate (increase or decrease) the biological activity of the studied Collagenase enzyme. Important findings from the conducted experiments showed that the biological activity of Collagenase enzyme is increased by 7-15% and 4-15% upon irradiation at 3Hz and 8Hz for the magnetic flux densities of 0.5-2.5mT. The effects of the applied ELF PEMF exposure system on growth and proliferation of bacterial culture of S. aureus and E. coli have also been experimentally evaluated. All bacterial cultures exposed to ELF PEMF showed a decrease in their growth rate when compared to control samples. For S. aureus, a specific viability pattern “quadrature polynomial” was observed upon ELF PEMF irradiation. The occurrence of the frequency and magnetic flux density “windows” was observed at the higher end of the studied frequencies range and all magnetic flux densities except 1.5mT. Maximum relative decrease of 68.56% was observed at the frequency 300Hz and magnetic flux density 1.5mT. For E. coli, the overall observation is that E. coli bacteria were generally more responsive to the applied irradiation treatment, where the exponential relationship between the colony-forming unit (CFU) values (bacterial growth) and applied exposures was observed. The results obtained clearly demonstrate that the effects of irradiation on bacterial growth are frequency and magnetic flux density dependent. In general, the decrease in bacterial cell viability was achieved at all studied range of frequencies (2-500Hz) and every magnetic flux density (0.5mT, 1mT, 1.5mT, 1.5mT, 2mT and 2.5mT). Minimum and maximum changes in bacterial cells growth for the exposed samples were recorded at 3Hz and 0.5mT, and 500Hz and 2.5mT, respectively. The maximum effect observed at the 500Hz and 2.5mT corresponds to the relative decrease of 77.26 % in bacterial growth. The outcomes of this research project provides evidence based support to the hypothesis that optimal ELF PEMF parameters can induce therapeutic effects in proteins and cells and thereby, ELF PEMF therapies have a great potential for possible treatment of wounds and overall wound healing promotion

NASA Tech Briefs, October 1990

Topics: New Product Ideas; NASA TU Services; Electronic Components and Circuits; Electronic Systems; Physical' Sciences; Materials; Computer Programs; Mechanics; Machinery; Fabrication Technology; Mathematics and Information Sciences; Life Sciences

Instrumentation for Cryogenic Dynamic Nuclear Polarization and Electron Decoupling in Rotating Solids

Dynamic nuclear polarization (DNP) increases the sensitivity of nuclear magnetic resonance (NMR) using the higher polarization of electron radical spins compared to nuclear spins. The addition of electron radicals for DNP to the sample can cause hyperfine broadening, which decreases the resolution of the NMR resonances due to hyperfine interactions between electron and nuclear spins. Electron decoupling has been shown to attenuate the effects of hyperfine coupling in rotating solids. Magic angle spinning (MAS) DNP with electron decoupling requires a high electron Rabi frequency provided by a high-power microwave source such as a frequency-agile gyrotron. This dissertation describes the development of instrumentation to improve electron decoupling through a higher electron Rabi frequency, including two designs for frequency agile gyrotrons and a MAS rotor resonator to increase the effect of microwaves at the sample. Electron spin relaxation times are increased at cryogenic temperatures, enabling manipulation of electron spins with lower electron Rabi frequency. Therefore, a cryostat with interchangeable MAS-DNP NMR probes for DNP experiments ranging from 4-80 K has been constructed and tested