Measuring 3D indoor air velocity via an inexpensive low-power ultrasonic anemometer

The ability to inexpensively monitor indoor air speed and direction on a continuous basis would transform the control of environmental quality and energy use in buildings. Air motion transports energy, ventilation air, and pollutants around building interiors and their occupants, and measured feedback about it could be used in numerous ways to improve building operation. However indoor air movement is rarely monitored because of the expense and fragility of sensors. This paper describes a unique anemometer developed by the authors, that measures 3-dimensional air velocity for indoor environmental applications, leveraging new microelectromechanical systems (MEMS) technology for ultrasonic range-finding. The anemometer uses a tetrahedral arrangement of four transceivers, the smallest number able to capture a 3-dimensional flow, that provides greater measurement redundancy than in existing anemometry. We describe the theory, hardware, and software of the anemometer, including algorithms that detect and eliminate shielding errors caused by the wakes from anemometer support struts. The anemometer has a resolution and starting threshold of 0.01 m/s, an absolute air speed error of 0.05 m/s at a given orientation with minimal filtering, 3.1° angle- and 0.11 m/s velocity errors over 360° azimuthal rotation, and 3.5° angle- and 0.07 m/s velocity errors over 135° vertical declination. It includes radio connection to internet and is able to operate standalone for multiple years on a standard battery. The anemometer also measures temperature and has a compass and tilt sensor so that flow direction is globally referenced regardless of anemometer orientation. The retail cost of parts is $100 USD, and all parts snap together for ease of assembly

Qube - A CubeSat for Quantum Key Distribution Experiments

In a world of global satellite communication networks, it is crucial to ensure the security of these data links. QUBE is a project that will develop and launch a CubeSat for the downlink of strongly attenuated light pulses, with encoded quantum information, which can be used for the exchange of encryption keys. This 3U Pico-Satellite will be built using the UNISEC-Europe standard, which has been proven to provide a robust framework for increased reliability for CubeSat missions. In addition to advanced reaction wheels for precision pointing, the satellite will be carrying the DLR-OSIRIS optical downlink system as well as dedicated payloads for testing components required for quantum key distribution. A miniaturized quantum random number generator (QRNG) will create a sequence of numbers, which can be used to set the quantum states of the light. The light pulses will then be downlinked to the optical ground station at DLR in Oberpfaffenhofen, Germany, which is equipped with the corresponding components for receiving the quantum states. Additionally, the random numbers will partially be made available via an RF downlink. This will allow evaluating the link loss as well as the noise and errors in the transmission of quantum signals. In QKD, due to the underlying quantum mechanics, any attempt of reading the quantum states will alter them, which makes interceptions easily detectable. The quantum communication experiments will evaluate whether secure communication links are possible even on a CubeSat scale. A major challenge for building the required CubeSat is the attitude determination and control system that will provide precise pointing. This work will outline detailed mission requirements as well as the chosen subsystems for tackling these challenges in order to deliver a successful mission

Multi-GNSS integer ambiguity resolution enabled precise positioning

In this PhD thesis multi-Global Navigation Satellite System (GNSS) positioning results when combining the American Global Positioning System (GPS), Chinese BeiDou Navigation Satellite System (BDS), European Galileo and Japanese Quasi-Zenith Satellite System (QZSS) will be presented. The combined systems will be evaluated in comparison to the single-systems, for short (atmosphere-fixed) to long (atmosphere-present) baselines. It will be shown that the combined systems can provide for improved integer ambiguity resolution and positioning performance over the single-systems

A novel design and simulation of a mechanical coordinate based photovoltaic solar tracking system

Various methods have been developed to increase electrical energy production gains in photovoltaic (PV) systems. These can be classified as solar tracking systems, cooling systems and methods of reducing the effect of shading. In order to maximise the PV energy yield, the PV systems must follow the sun. In this study, the effect of solar tracking systems on the energy yield gains of PV systems is investigated, and various types of solar tracking systems are discussed in detail. To ensure accuracte tracking of the postion of the sun, a new, low-cost, system has been developed that employs a global positioning system (GPS) module, compass and accelerometer. With this necessary angle information a dual-axis coordinate-based solar tracking system was designed using the Arduino Mega 2560 microcontroler with home-built control software. The system is validated by comparing it to a fixed angle system and an energy yield gain of 33–38% is found

The COMPASS Experiment at CERN

The COMPASS experiment makes use of the CERN SPS high-intensitymuon and hadron beams for the investigation of the nucleon spin structure and the spectroscopy of hadrons. One or more outgoing particles are detected in coincidence with the incoming muon or hadron. A large polarized target inside a superconducting solenoid is used for the measurements with the muon beam. Outgoing particles are detected by a two-stage, large angle and large momentum range spectrometer. The setup is built using several types of tracking detectors, according to the expected incident rate, required space resolution and the solid angle to be covered. Particle identification is achieved using a RICH counter and both hadron and electromagnetic calorimeters. The setup has been successfully operated from 2002 onwards using a muon beam. Data with a hadron beam were also collected in 2004. This article describes the main features and performances of the spectrometer in 2004; a short summary of the 2006 upgrade is also given.Comment: 84 papes, 74 figure

Advanced flight control system study

The architecture, requirements, and system elements of an ultrareliable, advanced flight control system are described. The basic criteria are functional reliability of 10 to the minus 10 power/hour of flight and only 6 month scheduled maintenance. A distributed system architecture is described, including a multiplexed communication system, reliable bus controller, the use of skewed sensor arrays, and actuator interfaces. Test bed and flight evaluation program are proposed

UAV Attitude Estimation Using Low-Frequency Radio Polarization Measurements

A method of attitude determination, which makes use of measurements of the polarization of the magnetic field of low-frequency (LF) radio signals, is presented and evaluated. This approach offers advantages relative to existing accelerometer-based systems in high-acceleration, cost-constrained environments such as small fixed-wing unmanned aerial vehicles. Flight test results are presented which demonstrate that LF polarization measurements can be used to obtain a significantly more accurate result than traditional approaches.Engineering and Physical Sciences Research Council (Doctoral Training Account award)This is the author accepted manuscript. The final version is available from IEEE via http://dx.doi.org/10.1109/TAES.2016.263750