Research on the properties of circadian systems amenable to study in space

Three areas of inquiry are reported for the Skylab Experiment S-071 whose objective was to study the circadian system of a mammal during space flight. The thermoregulatory behavior of the Perognathus longimembris, or little pocket mouse, was studied under conditions of constant dark and constant temperature in the prolonged weightless environment of Skylab. The following specific questions were studied: (1) the effects of weightlessness on circadian periodicity in the little pocket mouse; (2) stability of the free-running circadian period of body temperature of the little pocket mouse exposed to simulated launch stress; and (3) characteristics of the circadian rhythm of body temperature in the little pocket mouse. Diagrams of the electronic circuitry and hardware used in the experiment are shown and results are given in both graphical and tabular form. The methods used in the experiment are fully documented, along with conclusions and recommendations for future research

Voyager spacecraft phase B, task D. Volume 2 - System description. Book 3 - Guidance and control, computer and sequencer, power subsystem, electrical system Final report

Baseline design and functional requirements of Voyager spacecraft guidance and control, computer and sequencer, and power subsystems, and electrical syste

Structural refinement and electrochemical properties of one dimensional (ZnO NRs)1-x(CNs )x functional hybrids for serotonin sensing studies

Herein, the efficient serotonin (5-HT) sensing studies have been conducted using the (ZnO NRs) 1−x(CNs) x nanocomposites (NCs) having appropriate structural and electrochemical properties. Initially, the different compositions of ZnO nanorods (NRs), with varying content of carbon nanostructures (CNs=MWCNTs and RGO), are prepared using simple in-situ wet chemical method and thereafter these NCs have been characterized for physico-chemical properties in correlation to the 5-HT sensing activity. XRD Rietveld refinement studies reveal the hexagonal Wurtzite ZnO NRs oriented in (101) direction with space group ‘P6 3mc’ and both orientation as well as phase of ZnO NRs are also retained in the NCs due to the small content of CNs. The interconnectivity between the ZnO NRs with CNs through different functional moieties is also studied using FTIR analysis; while phases of the constituents are confirmed through Raman analysis. FESEM images of the bare/NCs show hexagonal shaped rods with higher aspect ratio (4.87) to that of others. BET analysis and EIS measurements reveal the higher surface area (97.895 m 2/g), lower charge transfer resistance (16.2 kΩ) for the ZCNT 0.1 NCs to that of other NCs or bare material. Thereafter, the prepared NCs are deposited on the screen printed carbon electrode (SPCE) using chitosan as cross-linked agent for 5-HT sensing studies; conducted through cyclic voltammetry (CV) and square wave voltammetry (SWV) measurements. Among the various composites, ZCNT0.1 NCs based electrodes exhibit higher sensing activity towards 5-HT in accordance to its higher surface area, lower particle size and lower charge transfer resistance. SWV measurements provide a wide linear response range (7.5–300 μM); lower limit of detection (0.66 μM), excellent limit of quantification (2.19 μM) and good reproducibility to ZCNT 0.1 NCs as compared to others for 5-HT sensing studies

Interfacing with a capacitance based strain sensor for use in CNC milling applications

Smart machining provides feedback to the machine in an attempt to avoid pushing the cutting tool beyond its capability or lifetime, potentially ruining the tool or workpiece. This thesis details the process of designing a circuit board for communication with a capacitance-based wireless strain sensor to achieve a target strain resolution of 10muepsilon, at a target measurement rate of 100 kHz. The sensor resonates at a particular frequency, which varies as a function of strain on the tool. The strain is calculated as a function of the change in the resonant frequency. The results of this research are presented in terms of the effective sampling rate based on the number of samples to average in order to obtain a measurement, where based on the noise in the measurement, 280 samples must be averaged in order to obtain a strain measurement. These results demonstrate the successful concept of wireless strain measurement with a capacitance-based sensor

Microprocessor-Based Systems Control for the Rigidized Inflatable Get-Away-Special Experiment

As the demand for space based communications and faster data throughput increase, satellites are becoming larger. Larger satellite antennas help to provide the needed gain to increase communications in space. Compounding the performance and size trade-offs are the payload weight and size limit imposed by the launch vehicles. Inflatable structures offer a cost saving opportunity since the structure is significantly lighter and has a reduced storage volume. This allows for smaller launch vehicles and for increased performance capabilities. Inflatable structures offer possibilities for increased satellite lifetimes, increased communications capacity, and reduce launch costs. This thesis develops and implements the computer control system and power system to support the Rigidized Inflatable Get-Away-Experiment. The autonomous computer system controls the flow of the experiment while at the same time collecting and recording temperature, pressure, vibration, and image data. The computer system consists of two processors, one for experiment control and sensor data collection and the second for image data collection. These two systems can work simultaneously to control the flow of the experiment and meet the experiment objectives. Examples of the data collection include heating curves, pressure, tube transfer function plots and images. This thesis also develops the Matlab® tools required to analyze the data collected by the computers for post-flight data processing. This thesis lays the groundwork for a microprocessor-based architecture for autonomous space experiments. This pioneering effort has been selected for flight testing on-board the U.S. Space Shuttle

Design and implementation of DSP-based magnetic control system for capsule endoscope

PhD ThesisEarly detection methods are key to reducing morbidity rates from digestive tract cancer which is currently one of the fastest growing cancers in the World. Capsule endoscopes (CEs) are a new technology that can be used to improve early detection of the gastrointestinal (GI) tract disorder. The device integrates the technologies such as image processing, optoelectronic engineering, information communication, and biomedical engineering. The capsule is the size and shape of a pill and contains an optoelectronic camera, antenna, transmitter, battery and optoelectronic illuminating light emitting diodes (LEDs). The small size of these devices enables them to offer many advantages over conventional endoscopes such as accessibility to the entire intestine and minimising the risk of perforation, particularly for patients with difficult anatomy (e.g. post-operative scar tissue). Currently used devices are passive and can only follow the natural transit of the intestines, and hence there is considerable interest in methods of controlled actuation for these devices. In this thesis, a novel actuation system based on magnetic levitation is designed, developed and implemented, utilizing a small permanent magnet embedded within the capsule and an arrangement of digitally controlled electromagnets outside the body. The proposed approach is that the magnet can be moved and oriented by DC magnetic force and torque produced by coils placed outside of the human body, with a suitable position feedback sensor enabling closed-loop control. Theoretical analyses of the proposed actuation system are presented which model the magnetic field, force and torque exerted by electromagnetic coil on the embedded magnet. Based on the distribution of the magnetic field, an optimal geometry for the coils is proposed in order to achieve a levitation distance which is realistic for the inspection of the GI tract. Two types of systems are investigated in the thesis, namely single-input single-output (SISO) and multi-input multi-output (MIMO), and the dynamics of these systems are modelled in state space form and hence linear controllers are designed for capsule actuation. The controllers are simulated using Matlab/ Simulink tools to realize the mathematical analysis of the system, and then implemented digitally in real-time using Texas Instruments (TI) TMS320F2812 Digital Signal Processor (DSP) to validate the proposed actuation system. In the SISO system, a linear one degree of freedom (1DOF) proportionalintegral- derivative (PID) controller is designed to move the inserted magnet in the vertical dimension within an area around the operating point and to maintain it at a desired position. A realistic simulation model is designed and implemented to evaluate the proposed controller. Simulation results have shown that the controller is able to successfully hold the embedded magnet in the desired position. For practical validation, the PID controller is implemented in real-time on the DSP system, where pulse width modulation (PWM) is generated to control the coil current, and Hall effect sensors are used for position feedback. Experimental results are obtained under step and square wave input demand. In the proposed system, high frequency noise on the position sensor is initially rejected by hardware implementation of resistor capacitor-low pass filter (RC-LPF) circuit. The accuracy of the position feedback is increased by calibrating the DSP’s on-chip analogue-digital converter (ADC) in order to reduce conversion error due to inherent gain and offset errors. To further reduce the influence of the position feedback noise, an average of ten repeated samples based on mean filter is implemented by the DSP in order to reduce the influctuation of the sensor reading. The tracking performance of the actuation system based on two Hall effect sensors on the opposite coil’s poles is investigated under step trajectory input. In an improved actuation system, position feedback is provided by using an AC magnetic field to obtain the capsule position information, decoupling this from the DC actuation field. The noise of the position feedback in the improved system is reduced by replacing the PWM current drive with a linear power amplifier driven from a digital to analogue converter (DAC), hence reducing AC interference. Positioning sensor noise was found to be further reduced by implementing digital filtering based on a coherent detector using the DSP, without increasing response time. The performance of the actuation system using these position sensors is compared based on settling time, overshoot, steady-state error, and control input parameters in order to validate the proposed improvement in the position feedback. The experimental results have shown that the controller based on both sensing strategies satisfactory control of the magnet’s position. However, the response of the system based on AC position sensing has the shortest settling time, smallest overshoot value and steady-state error. In the MIMO system, several linear controllers such as pole placement (PP), Entire Eigenstructure Assignment (EEA), and linear Quadratic regulator (LQR) techniques are designed and their tracking performances are compared. Simulation results have shown that, based on acceptable control inputs, the LQR controller has the fastest response with minimal overshoot value and steady state error. However, the LQR controller based on 2DOF is unable to maintain stable control of the magnet due to the insufficient position feedback from the two coil sensors. Specifically, it is not possible to achieve a stable 2D system since the orientation angle of the magnet is not resolvable. Therefore, the position feedback is improved by obtaining the device position and orientation information from a pair of 3-axis orthogonal coils. A realistic simulation model for the 3DOF LQR controller is designed and implemented to evaluate the developed system. Simulation results have shown that this controller is can achieve the necessary stability. In conclusion, based on the results from the 1D control system, the thesis shows that the DC magnetic field, which is used for capsule movement, can be also used to provide the controller acceptable position feedback. However, the use of AC magnetic field for positioning purpose provides more accurate position information. In order to implement 2DOF control system successfully, two 3-axis orthogonal coil sensors are considered which are used to provide the actuation algorithm with more accurate feedback of position and orientation information.Ministry of Higher Education, Iraq

Space programs summary no. 37-58, volume 3 for the period 1 June - 31 July 1969. Supporting research and advanced development

Review of developments in current engineering and scientific work at JP

Study of a high resolution facsimile system experiment on the surface of the planet Mars Final report

High resolution facsimile transmission camera capsule for Mars planetary landin

Analysis and design of a capsule landing system and surface vehicle control system for Mars exploration

A number of problems related to the design, construction and evaluation of an autonomous roving planetary vehicle and its control and operating systems intended for an unmanned exploration of Mars are studied. Vehicle configuration, dynamics, control, systems and propulsion; systems analysis; terrain sensing and modeling and path selection; and chemical analysis of samples are included

Wide Bandgap Based Devices: Design, Fabrication and Applications, Volume II

Wide bandgap (WBG) semiconductors are becoming a key enabling technology for several strategic fields, including power electronics, illumination, and sensors. This reprint collects the 23 papers covering the full spectrum of the above applications and providing contributions from the on-going research at different levels, from materials to devices and from circuits to systems