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Active Noise Control (ANC) systems have proved to be a very efficient way to reduce low-frequency acoustic noise. On this domain, passive techniques like enclosures, barriers and silencers tend to be relatively large, costly and ineffective. Although many studies and articles have been published in order to improve performance and stability, the implementation of a real-time, stable and robust system still faces several theoretical and practical challenges.
Radio frequency (RF) power amplifiers (PA) are the most power consuming components of a mobile communications unit. They are used to convert the DC power from the battery into RF power delivered to the antenna. In a cell phone it becomes very important to use highly efficient power amplifiers, such as Class C and Class E PAs, to increase the talk time which is directly proportional to the battery life. On the other hand, these RF PAs are inherently nonlinear and produce spectral regrowth and other undesirable effects.
Recent developments in information and communication technology, along with advanced displaying techniques and high computational performance open up new visualisation methods to both scientists and lecturers. Thus simulations of complex processes [1] can be computed and visualised in image sequences. The particular idea in our approach is the outsourcing of computationally intensive calculations to servers which then send the results back to mobile users. In order to improve interpretations of the visualised results, users can view them in a 3D-perspective or stereoscopically, given the technical requirements. Today’s technology even permits to view these visualisations on a mobile phone. An example for such a computationally intensive calculation originating from the theory of relativity is depicted in Figure 4.1-1.
Hybrid drives for automotive application are extensively discussed. In contrast, the company HEINZMANN, the University of Karlsruhe and the University of Applied Sciences Offenburg concentrate on hybrid drives for industrial, offroad purposes in a joint project. These applications promise a much higher fuel saving potential, particularly if highly frequent load cycles are present. Hybrid drive systems offer additional advantages including reduced exhaust aftertreatment requirements due to engine downsizing, better engine dynamics, emissions and noise reduction.
Air traffic control today still works primarily with classical sensors like primary and Secondary Surveillance Radars (PSR, MSSR, Mode-S) [1]. Upcoming is a new technology, ADS (Automatic Dependent Surveillance), which derives positional information from a Global Navigation Satellite System (GNSS) and distributes this data together with additional information from the on-board Flight Management System (FMS) to other aircraft (air-to-air) and to ADS groundstations (air-to-ground). [2] Because the transmission of the data takes place on a shared broadcasting media, like the 1090 MHz Extended Squitter (ES) channel, the technology is also referred to as ADS-Broadcast (ADS-B).
This study focuses on the experimental and numerical investigations on a commercial Ranque-Hilsch vortex tube. Ranque-Hilsch vortex tubes have many applications in industry and production as they can generate a very cold flow just from pressurized air .e.g. machine tool cooling. Main objective of this study is the energy separation in the flow field which results in a temperature drop on the cold exit of the tube. This was investigated experimentally by measuring the outlet temperature on the cold exit and the pressure drop on the flow restrictor valve on the hot exit. At a pressure drop of 0.5 bar the vortex tube showed the best performance by reaching a cold exit temperature of –16.7 °C. The Inlet flow was pressurised air at 20 °C and 6 bar.<br /> The numerical analysis was carried out by full 3D steady state CFD-simulation using the commercial software ANSYS CFX 11.0. The three dimensional model represented a 120° sector of the tube using periodic boundary conditions. A comparison between different turbulence models (k – å, RNG k – å, k – ù, SST) was carried out. The classic k – å two layer turbulence model showed the best results compared to the experiment. The energy separation and the drop in cold exit temperature are highest when the viscous work term is included into the energy equation. These effects of including the viscous work term into the energy separation have also been investigated.
Plant oils may be used as a sustainable, nearly CO2neutral fuel for diesel engines. This work investigates experimentally the particulate and gaseous emissions of diesel engines fuelled with different non-esterified, pure plant oils. The data are collected from three engines: a) Common rail 1.7 liter passenger car engine from Opel AG b) 12.8 liter truck engine from VOLVO c) Truck engine from MAN AG.
The emissions of the MAN engine have been used to perform AMES tests to analyze possible health impacts of plant oil operation. Finally, all emission results with plant oils have been compared to traditional gas oils.
In the recent two years the authors have developed a light weight and low power flight control system for model helicopters consisting of an attitude and heading reference system (AHRS), a navigator (INS) augmented with GPS, barometric altitude sensor and a magnetic sensor, a flight control computer (FCC) and bidirectional ground data links. The system has been tested on a commercial stunt flight model helicopter. The AHRS consists of three MEMS-gyros, two 2-axis MEMS accelerometers and a microcontroller performing the required sensor compensation and data processing to generate attitude angles and true rate and acceleration data of the flying platform. The heading angle is augmented with a 2-axis magnetic sensor. The AHRS is stunt flight capable. The INS integrates the acceleration data to obtain velocity and position data. All data are calculated in both the helicopter and the local earth frame with 50 Hz rate. The algorithm is augmented with GPS data for the lateral movement and with a barometric altitude sensor for the vertical movement. The barometric data are compensated for air pressure changes due to the helicopter main rotor. The FCC contains a set of control loops in order to stabilize the helicopter in all axis and to perform commanded velocity and position tasks. The sampling rate for the control loops is again 50 Hz allowing flight control with high bandwidth. Various safety features are implemented in the software. The bidirectional data link is based on a 2.4 GHz Bluetooth Class I RF-link with a 115 kbaud data rate. A dipole antenna is used on the helicopter, an automatically tracking patch antenna is used on the ground. For commanded velocity flight a standard 35 MHz RF-link is used. For data sampling, monitoring and mode control a laptop is used on the ground. Several operating modes are implemented ranging from commanded velocity flight to simple automatic stunt flight according to predefined flight tracks. The model helicopter is an ALIGN TREX 600 with 3 kg flight mass and a brushless electric motor. The rotor diameter is 1.40 m. The helicopter is able to carry a payload which mass depends on the size of the installed LiPo-cells and the purpose of the flight mission. The system has been tested in quite a few flight tests and missions. The helicopter is controlled safely up to wind loads of at least 5 Beaufort - 6 Beaufort. Data and video captures will be presented. If permission is granted, a demonstration flight will be performed on the premises of the conference.
This paper presents an enhancement on QPSK modulation technique for near field communication (NFC). The enhanced modulation is based on continuous-phase QPSK with Gaussian filtering during switch from one phase to the other. Signal processing is done digitally with minimum external discrete components for air interface. The telemetry system can be used to assist a smart capsule (slave) that can be swallowed to establish data communication with external device (master). The system is designed, simulated, and emulated on FPGA showing 20 dB attenuation on side-lobes of the spectrum.
This paper describes the magmaOffenburg 3D simulation team trying to qualify for RoboCup 2009. It focuses on two distinctive features of the team: decisions making using extended behavior networks and its software architecture and implementation in Java to open the simulation for the Java community.