Feasibility Study of a Satellite Solar Power Station

A feasibility study of a satellite solar power station (SSPS) was conducted to: (1) explore how an SSPS could be flown and controlled in orbit; (2) determine the techniques needed to avoid radio frequency interference (RFI); and (3) determine the key environmental, technological, and economic issues involved. Structural and dynamic analyses of the SSPS structure were performed, and deflections and internal member loads were determined. Desirable material characteristics were assessed and technology developments identified. Flight control performance of the SSPS baseline design was evaluated and parametric sizing studies were performed. The study of RFI avoidance techniques covered (1) optimization of the microwave transmission system; (2) device design and expected RFI; and (3) SSPS RFI effects. The identification of key issues involved (1) microwave generation, transmissions, and rectification and solar energy conversion; (2) environmental-ecological impact and biological effects; and (3) economic issues, i.e., costs and benefits associated with the SSPS. The feasibility of the SSPS based on the parameters of the study was established

A portable spectrometer for use from 5 to 15 micrometers

A field portable spectrometer suitable for collecting data relevant to remote sensing applications in the 8 to 12 micrometer atmospheric window has been built at the Jet Propulsion Laboratory. The instrument employs a single cooled HgCdTe detector and a continuously variable filter wheel analyzer. The spectral range covered is 5 to 14.5 micrometers and the resolution is approximately 1.5 percent of the wavelength. A description of the hardware is followed by a discussion of the analysis of the spectral data leading to finished emissivity and radiance spectra. A section is devoted to the evaluation of the instrument performance with respect to spectral resolution, radiometric precision, and accuracy. Several examples of spectra acquired in the field are included

Süsteemi arhitektuur ning komponentide valimine ESTCube-2 toitealamsüsteemi jaoks

This thesis is focused on the architecture of the electrical power system (EPS) and implementations of the various subsystems within the EPS for ESTCube-2 nanosatellite. The main goals are to establish a high level system architecture compatible with the rest of the satellite and investigate solutions for the battery management and protection (BMPS) and the voltage conversion and power distribution systems (VCPDS). In this work, an overview is given of the ESTCube-2 mission and the satellite’s architecture. Based on the satellite architecture, requirements are set for the EPS subsystems to be investigated. For the BMPS, two hot-swap controller based solutions are investigated, prototyped and tested. For the VCPDS, two load switch designs are evaluated, six different voltage converters are characterized and solutions for the power distribution system are proposed. Based on the testing results, recommendations are made for the final implementation

An efficient telemetry system for restoring sight

PhD ThesisThe human nervous system can be damaged as a result of disease or trauma, causing conditions such as Parkinson’s disease. Most people try pharmaceuticals as a primary method of treatment. However, drugs cannot restore some cases, such as visual disorder. Alternatively, this impairment can be treated with electronic neural prostheses. A retinal prosthesis is an example of that for restoring sight, but it is not efficient and only people with retinal pigmentosa benefit from it. In such treatments, stimulation of the nervous system can be achieved by electrical or optical means. In the latter case, the nerves need to be rendered light sensitive via genetic means (optogenetics). High radiance photonic devices are then required to deliver light to the target tissue. Such optical approaches hold the potential to be more effective while causing less harm to the brain tissue. As these devices are implanted in tissue, wireless means need to be used to communicate with them. For this, IEEE 802.15.6 or Bluetooth protocols at 2.4GHz are potentially compatible with most advanced electronic devices, and are also safe and secure. Also, wireless power delivery can operate the implanted device. In this thesis, a fully wireless and efficient visual cortical stimulator was designed to restore the sight of the blind. This system is likely to address 40% of the causes of blindness. In general, the system can be divided into two parts, hardware and software. Hardware parts include a wireless power transfer design, the communication device, power management, a processor and the control unit, and the 3D design for assembly. The software part contains the image simplification, image compression, data encoding, pulse modulation, and the control system. Real-time video streaming is processed and sent over Bluetooth, and data are received by the LPC4330 six layer implanted board. After retrieving the compressed data, the processed data are again sent to the implanted electrode/optrode to stimulate the brain’s nerve cells

Thin-film GaAs photovoltaic solar energy cells Final report

Thin film gallium arsenide photovoltaic solar cell

Development of a heuristic methodology for designing measurement networks for precise metal accounting

This thesis investigates the development of a heuristic based methodology for designing measurement networks with application to the precise accounting of metal flows in mineral beneficiation operations. The term 'measurement network' is used to refer to the 'system of sampling and weight measurement equipment' from which process measurements are routinely collected. Metal accounting is defined as the estimation of saleable metal in the mine and subsequent process streams over a defined time period. One of the greatest challenges facing metal accounting is 'uncertainty' that is caused by random errors, and sometimes gross errors, that obtain in process measurements. While gross errors can be eliminated through correct measurement practices, random errors are an inherent property of measured data and they can only be minimised. Two types of rules for designing measurement networks were considered. The first type of rules referred to as 'expert heuristics' consists of (i) Code of Practice Guidelines from the AMIRA P754 Code, and (ii) prevailing accounting practices from the mineral and metallurgical processing industry which were obtained through a questionnaire survey campaign. It was hypothesised that experts in the industry design measurement networks using rules or guidelines that ensure requisite quality in metal accounting. The second set of rules was derived from the symbolic manipulation of the general steady-state linear data reconciliation solution as well as from an intensive numerical study on the variance reduction response of measurements after data reconciliation conducted in this study. These were referred to as 'mathematical heuristics' and are based on the general principle of variance reduction through data reconciliation. It was hypothesised that data reconciliation can be used to target variance reduction for selected measurements by exploiting characteristics of entire measurement networks as well as individual measurement characteristics

The stretch-activated potassium channel TREK-1 in rat cardiac ventricular muscle

Cardiac TREK-1 like potassium channels play an important role in the function of cardiomyocytes. A novel low-conductance TREK-1 like potassium channel and a high-conductance TREK-1 like potassium channel in rat cardiomyocytes are described in this thesis. The biophysical properties of the two cardiac TREK-like channels were similar to those of TREK-1a or TREK-1b channels expressed in HEK293 cells, which both displayed a low- and a high-conductance mode. Using cell-specific RT-PCR we found strong expression of a splice variant of rat TREK-1, denoted TREK-1b, in which the N-terminus is extended by 15 amino acids compared to the 'classical' TREK-1a channel protein. Immunohistochemistry with antibodies against TREK-1 showed localization of the channel in longitudinal stripes at the external surface membrane of cardiomyocytes. When the cardio-myocytes were mechanically stretched using a glass stylus, an outwardly rectifying K+ current component could be detected in whole-cell recordings. In single-channel recordings with symmetrical high K+ solution, two TREK-like channels with 'flickery-burst' kinetics were found: a ‘high-conductance?K+ channel (1325 pS at positive potentials) and a novel ‘low-conductance?channel (415 pS at positive potentials). The low-conductance channel could be activated by negative pressure in inside-out, positive pressure in outside-out patches, intracellular acidification and arachidonic acid. Its open probability was strongly increased by depolarization, due to decreased duration of gaps between bursts. The biophysical properties of the two cardiac TREK-like channels were similar to those of TREK-1a or TREK-1b channels expressed in HEK293 cells, which both displayed a low- and a high-conductance mode. Our results suggest that the TREK-like channels found in rat cardiomyocytes may reflect two different modes of TREK-1. The current flowing through these mechano-gated channels may serve to counterbalance the inward current flowing through stretch-activated non-selective cation channels during the filling phase of the cardiac cycle and thus to prevent the occurrence of ventricular extrasystoles