Top Physics at the LHC

Top quark physics will be a prominent topic in Standard Model physics at the LHC. The enormous amount of top quarks expected to be produced will allow to perform a wide range of precision measurements. An overview of the planned top physics programme of the ATLAS and CMS experiments at the LHC is given.Comment: Contribution to the Conference Proceedings of the "XXXXth Rencontres de Moriond, QCD and High Energy Hadronic Interactions, La Thuile, March 12-19, 2005

Preparation of Loads and Aeroelastic Analyses of a High Altitude, Long Endurance, Solar Electric Aircraft

High altitude, long endurance aircraft can serve as platform for scientists to make observations of the earth over a long period of time. Staying airborne only by solar electric energy is, as of today, a challenge for the aircraft design and requires an extremely light weight structure at the edge of the physically possible. This paper focuses on the loads and aeroelastic aspects of such a configuration, discusses the selected strategies and presents the applied methods and tools, including the resulting models prepared for the HAPomega configuration currently under development at the DLR. Because of the structural flexibility and the slow speed of the aircraft, flight mechanical and flight control aspects interact with aeroelastics e.g. during a gust encounter, making a non-linear time domain simulation necessary. Both maneuver and gust loads are used for the structural sizing and result in a very light and slender airframe with very low eigenfrequencies

Fault-Tolerant Control for a High Altitude Long Endurance Aircraft

High Altitude Long Endurance (HALE) aircraft consist of extremely light-weight structures in combination with a high wingspan and high aspect ratio. The combination of these properties results in an unique dynamic behavior of the aircraft system featuring a strong interaction of structural and rigid body eigenmodes. These characteristics lead to specific demands on the robustness and fault tolerance of flight control algorithms of such aircraft. The control system must be able to navigate the aircraft safely along defined tracks even in case of fault scenarios. Due to the size of these aircraft they are usually over-actuated featuring multiple redundant control surfaces. This redundancy is used in this paper to design a fault tolerant control system ensuring optimal control performance during fault scenarios. The strategy is based on a fault detection and isolation (FDI) algorithm to detect malfunctioning control surfaces. This fault information is used to switch to alternate control laws in a multi-model control approach. The FDI filters are designed using the nullspace-based design paradigm, while the alternate controllers are synthesized applying structured H1 control design techniques

Baseline Flight Control System for High Altitude Long Endurance Aircraft

High Altitude Long Endurance (HALE) aircraft consist of extremely light-weight structures in combination with a high wingspan and high aspect ratio. The coupling of these properties results in a dynamic behavior of the aircraft system which is different to classical transport or unmanned aircraft configurations. The key finding in the analysis of the dynamic behavior ofthe aeroelastic HALE aircraft is a strong interaction of structural and rigid body eigenmodes.This leads to challenges in the design of a robust flight control algorithm for the full flight envelope with state-of-the-art techniques. This work addresses these difficulties and proposes a generic design process which can be used to develop flight control algorithms for HALE aircraft. The design process starts with the definition of specific performance and robustness criteriafor HALE flight control laws which emerge from the combination of general aircraft design standards with the limitations and capabilities of theHALEconfiguration. Subsequently, again-scheduled, fixed structure control design architecture is proposed. The inner loop controldesign is enriched with envelope protection functionalities. The design process concludes withan extensive validation and verification process to clear the baseline flight control system forflight testing. The proposed design process is applied to the German Aerospace Center’s newlydeveloped HALE platform

Exports and inputs of organic carbon on agricultural soils in Germany

The quantity and quality of organic carbon (Corg) input drive soil Corg stocks and thus fertility and climate mitigation potential of soils. To estimate fluxes of Corg as net primary production (NPP), exports, and inputs on German arable and grassland soils, we used field management data surveyed within the Agricultural Soil Inventory (n = 27.404 cases of sites multiplied by years). Further, we refined the concept of yield-based Corg allocation coefficients and delivered a new regionalized method applicable for agricultural soils in Central Europe. Mean total NPP calculated for arable and grassland soils was 6.9 ± 2.3 and 5.9 ± 2.9 Mg Corg ha-1 yr-1, respectively, of which approximately half was exported. On average, total Corg input calculated did not differ between arable (3.7 ± 1.8 Mg ha-1 yr-1) and grassland soils (3.7 ± 1.3 Mg ha-1 yr-1) but Corg sources were different: Grasslands received 1.4 times more Corg from root material than arable soils and we suggest that this difference in quality rather than quantity drives differences in soil Corg stocks between land use systems. On arable soils, side products were exported in 43% of the site * years. Cover crops were cultivated in 11% of site * years and contributed on average 3% of the mean annual total NPP. Across arable crops, total NPP drove Corg input (R2 = 0.47) stronger than organic fertilization (R2 = 0.11). Thus, maximizing plant growth enhances Corg input to soil. Our results are reliable estimates of management related Corg fluxes on agricultural soils in Germany

Exploring an option space to engineer a ubiquitous computing system

Engineering natural and appropriate interactive behaviour in ubiquitous computing systems presents new challenges to their developers. This paper explores formal models of interactive behaviour in ubiquitous systems. Of particular interest is the way that these models may help engineers to visualise the consequences of different designs. Design options based on a dynamic signage system (GAUDI) are explored using different instances of a generic model of the system.EPSRC -Engineering and Physical Sciences Research Council(EP/F01404X/1

Robust Path-following Control with Anti-Windup for HALE Aircraft

In this paper, a robust path-tracking controller for a High Altitude Long Endurance (HALE) aircraft is presented. The main control paradigm for operating a HALE aircraft consists of a basic path following control, i.e. tracking a reference flight path and airspeed while dealing with very limited thrust. The priority lies in keeping airspeed inside the small flight envelope of HALE aircraft even during saturated thrust. For the basic path following objective, a mixed sensitivity approach is proposed which can easily deal with decoupled tracking and robustness requirements. To deal with saturated control inputs, an anti-windup scheme is incorporated in the control design. A novel observer-based mixed sensitivity design is used which allows directly using classical anti-windup methods based on back-calculation. The control design is verified in nonlinear simulation and compared to a classical total energy control based controller

Flight Testing Total Energy Control Autopilot Functionalities for High Altitude Aircraft

In this paper the design and flight testing of a Total Energy Control System (TECS) autopilot for a High Altitude Long Endurance (HALE) aircraft is presented. Autopilot control for HALE aircraft is a well-fitting application for the TECS control strategy, as this enables energy-efficient, decoupled airspeed and flight path control with explicitly handling thrust limitation. To achieve a realistic validation of the controller before moving towards the integration on the HALE platform, the flight testing is carried out on a Cessna Citation passenger aircraft. It has been proven that the adjustments required to implement the control laws on the Cessna Citation passenger aircraft are minimal. This indicates that the Cessna Citation aircraft serves excellently as a hardware platform and can be utilized for the validation of flight control code integration and functionality. The results of the flight test are discussed, and insights gleaned for the future integration of TECS on the HALE aircraft are provided