Depth Image Processing for Obstacle Avoidance of an Autonomous VTOL UAV

We describe a new approach for stereo-based obstacle avoidance. This method analyzes the images of a stereo camera in realtime and searches for a safe target point that can be reached without collision. The obstacle avoidance system is used by our unmanned helicopter ARTIS (Autonomous Rotorcraft Testbed for Intelligent Systems) and its simulation environment. It is optimized for this UAV, but not limited to aircraft systems

Transformation of nitrogenous soil components by humivorous beetle larvae

The humivorous scarab beetles of the genus Pachnoda are indigenous to the African continent. The larvae of these insects preferably live in humic soils and feed on plant material and soil organic matter. However, the nature of the soil components used as carbon and energy sources are so far not understood. Previous studies indicated that peptides stabilized in humic acid model compounds are released and mineralized during gut passage. The present thesis documents extent of transformation and mineralization of peptidic compounds of the food soil. Further, the role of peptides in the nutrition of the larvae was estimated. The major site of proteolytic activity was located in the midgut. Also in the hindgut minor proteolytic activities were found. We postulate that the former activities are associated with host-secreted proteinases while the latter are mainly of microbial origin. As a consequence of high proteolytic activities in the midgut considerably high concentration of amino acids are accumulating. Relatively low turnover rates of amino acids suggest amino acids fermentation is the rate-limiting step in the midgut. In vivo, the insect host presumably takes up part of these amino acids. The high ammonia concentration in the hindgut is associated with high a turnover rate of amino acids. Addition of amino acids even stimulated the fermentative activity, suggesting that the supply of free amino acids by proteolysis is the rate-limiting step in this process. Thus, the hindgut is the main site of amino acid fermentation in the gut. Further, nitrification was indirectly observed by the accumulation of nitrite and nitrate. In high dilution steps of MPNs nitrite is subject to denitrification associated with gas production, most probably N2, supported by detectable losses of nitrogen from the food soil during gut passage. With the help of stable isotope probing, for several environments and diverse substrates the function of specific microbial populations was elucidated. However, previous experiments addressing the functions of the insect gut microbiota difficulties were observed using this method. In stable isotope probing experiments with whole guts of the wood-feeding termite Reticulitermes santonensis and hindgut of the humivorous beetle larvae of Pachnoda ephippiata using H13CO3– or 13C-labeled glucose it was confirmed that no isotope effect in the RNA of the gut microbiota can be detected. Also in incubations with 14C-labeled substrates, generally a more sensitive tracer, very little incorporation of substrate carbon into RNA was detected. We suggest several explanations as to why stable isotope probing in the gut of insects is not feasible. Since free nucleotides accumulate in the hindgut of Pachnoda marginata to high concentrations, we hypothesize that salvage pathways, known for many microorganisms as alternative for nucleotide biosynthesis, reduce the de novo formation of nucleic acids from substrate carbon. This hypothesis is supported by considerable inhibition of the incorporation of substrate carbon into RNA in incubations with Bacillus subtilis and Pseudomonas putida in the presence of ribonucleotides. In the insect gut environment, we reached the limits of the otherwise very convenient and successful application of stable isotope probing for the above-mentioned substrates. The actual reason still remains to be elucidated. The allopatric scarab beetle larvae of Pachnoda ephippiata and Pachnoda marginata are closely related and both feeding on soil organic matter. In the present thesis, the question is answered, whether the microbial community in the gut is similar, due to the same food source, or reveals differences as a consequence of the spatial separation. The composition of the bacterial communities of the midgut and the hindgut was studied with the help of terminal restriction fragment length polymorphism (T-RFLP) analysis, representing a PCR-based cultivation-independent technique. In both larvae, the bacterial midgut community is less diverse than the microbial hindgut community. In the T-RFLP profiles from the midgut of the two species only few T-RFs are shared with the hindgut profiles. By contrast, the community fingerprints of the hindguts appeared to be very similar, although the relative abundance of the single T-RF varied between the two beetle species. However, correspondence analysis of the T-RFLP dataset, we demonstrated significant species-dependent differences in the bacterial communities of both, the midgut and the hindgut, respectively. The feeding of larvae of Pachnoda marginata on different food soils did not result in significant differences in the bacterial hindgut community. Together, these results indicate that the differences in the gut microbiota are rather due spatial separation of the species than to differences in the diet

Updating Gender in Electronic Medical Records – A Commentary

It is argued in this commentary that many patient intake and permanent medical record forms make archaic assumptions about use of the word gender. A further argument is made for change that accounts for the needs of persons who do not readily identify as male or female. Several suggestions for making such accommodations available are offered

Combining Occupancy Grids with a Polygonal Obstacle World Model for Autonomous Flights

This chapter presents a mapping process that can be applied to autonomous systems for obstacle avoidance and trajectory planning. It is an improvement over commonly applied obstacle mapping techniques, such as occupancy grids. Problems encountered in large outdoor scenarios are tackled and a compressed map that can be sent on low-bandwidth networks is produced. The approach is real-time capable and works in full 3-D environments. The efficiency of the proposed approach is demonstrated under real operational conditions on an unmanned aerial vehicle using stereo vision for distance measurement

Masses of Small Bodies: Mass estimation of small solar system bodies using Radio Science data from close flybys

The Radio Science technique enables to estimate the mass and other gravitational parameters of a solar system body from spacecraft observations very precisely. It uses the radio link between ground station and spacecraft. The frequency shift of the radio signal is proportional to the relative velocity change between spacecraft and ground station. If a spacecraft performs a close flyby at a solar system body, the velocity of the spacecraft is changed by the gravitational attraction of the body. If all other contributions on the radio signal are known, the remaining frequency change is solely due to the gravitational attraction. A least square fit can be performed on the frequency residuals to derive from it gravitational parameters. Within this thesis models were developed and merged into a software package with which it is possible to determine the orbit of a spacecraft precisely and to predict accurately the frequency to be observed at a ground station. Models for extracting the frequency shift caused by the propagation of the radio signal through the ionosphere and troposphere of the Earth were incorporated. The accuracy of the predicted frequency, i.e. the difference between measurement and predict, is in the same order as the total Doppler velocity error in X-band from the thermal noise of the ground station and the transponder phase noise. Filtering techniques were established improving the signal to noise ratio at least by a factor of three. A numerical stable least square fitting procedure was introduced to fit the frequency change due to the gravitational attraction of a body onto the measured frequency residuals. Measurements from the close flyby of the Rosetta spacecraft at the asteroid Steins were analyzed with the developed method. Due to the large flyby distance no mass estimate was possible. A feasibility study was carried out for the upcoming flyby of Rosetta in July 2010 at the asteroid Lutetia. It is possible to estimate from this flyby the mass of Lutetia with an error of 1 %. Moreover, the developed method was applied to measurements of the Radio Science Experiment onboard Mars Express MaRS from two close flybys at the Mars moon Phobos in March 2006 and July 2008. The mass of Phobos was estimated from these flybys. The solution provides the most accurate value currently available for the mass of Phobos from close flybys. Information about the interior were derived from the precise mass estimate. Phobos has a high porosity which is discussed with respect to its origin. It seems to be unlikely that Phobos is a captured asteroid as suggested from first spectral measurements. It seems to be more likely that Phobos is the remnant of the collision between a body originating from the asteroid belt and a body remaining from the formation process of Mars. Mars Express will perform another flyby in March 2010 with a closest distance of 62 km. A feasibility study was performed from which it was derived that the C20 term of the gravity field of Phobos can be estimated with an error of 1 % with the developed method

Controlling arable weeds with natural substances as bio-based herbicides

Verbreitete Unkrautbekämpfungspraktiken sind intensive, wendende Bodenbearbeitung und der Einsatz chemisch-synthetischer Herbizide. Während die starke Abhängigkeit von synthetischen Herbiziden im konventionellen Ackerbau diskutiert wird, verstärkt sich gleichzeitig der Trend zur reduzierten Bodenbearbeitung als klimaschonende landwirtschaftliche Praxis. Diese Entwicklungen erfordern alternative Unkrautbekämpfungsmethoden. Die vorliegende Gewächshausstudie untersucht die Bekämpfung von 21 Ackerunkräutern und -ungräsern mit Bioherbiziden (Essig-, Zitronen- und Pelargonsäure sowie Magnesiumchlorid). Es werden vier natürliche Säuren und der Wirkstoff Glyphosat sowie eine Variante ohne Unkrautkontrolle verglichen. Zur Bewertung der Bekämpfung der Unkräuter und Ungräser dient der Grad der Nekrotisierung (0-100 %). Die Effizienz der natürlichen Säuren unterscheidet sich deutlich in der Bekämpfung von Unkräutern und Ungräsern, die höchste Wirkung wurde für Pelargonsäure ermittelt. Überwiegend gilt jedoch, dass die Wirksamkeit der natürlichen Säuren im Vergleich zu Glyphosat deutlich geringer ist. Dennoch deuten die Ergebnisse darauf hin, dass natürliche Säuren potentiell geeignet sind, spezifische Unkräuter bereits kurze Zeit nach der Applikation ausreichend zu bekämpfen. Es wurde eine hohe Wirksamkeit von Pelargonsäure zur Kontrolle von Ausfallraps nachgewiesen.Today farmers manage arable weeds with chemical tools or mechanical tillage practices. While the heavy reliance on synthetic herbicides in conventional arable farming is under discussion, the environmentally driven trend towards reduced tillage as a climate-smart agricultural practice becomes more prominent. These trends demand for alternative control methods of weeds. This greenhouse study investigates the control of 21 arable weeds with four natural substances. The experimental setup compared an untreated control with four natural substances (acetic, citric and pelargonic acid and magnesium chloride), and glyphosate was used as the common active ingredient for stubble and pre-sowing herbicide applications. The level of necrotisation (0-100%) was used to assess the efficacy of herbicide treatment. The efficacy differs substantially among the bio-based herbicides. For all natural substances, pelargonic acid has the highest mean efficacy for controlling the weeds tested in this experiment. For most weeds, however, the efficacy of natural substances is much lower compared to glyphosate. Nevertheless, the results indicate that natural substances as bio-based herbicides have the potential to offer an increased target specificity and rapid degradation in the soil. We found a high efficacy of pelargonic acid for controlling Brassica napus

Onboard Mission Management for a VTOL UAV Using Sequence and Supervisory Control

This chapter addresses the challenges of onboard mission management for small, low flying UAVs in order to reduce their dependency on reliable remote control. The system presented and tested onboard an unmanned aerial vehicle (UAV) provides levels of autonomy, scalable at runtime either by the operator or due to the absence of a data link. This way, it is a feasible approach towards autonomous flight guidance within the low-altitude domain (e.g. urban areas) where unpredictable events are likely to require onboard decision-making. In the following sections the problems of onboard mission management, embedded high level architectures and their implementation issues are discussed. The design of a onboard Mission Management System for a test platform with vertical take-off and landing (VTOL) capabilities is presented, followed by discussions of the implemented system and a research outlook

Accurate Cooperative Sensor Fusion by Parameterized Covariance Generation for Sensing and Localization Pipelines in CAVs

A major challenge in cooperative sensing is to weight the measurements taken from the various sources to get an accurate result. Ideally, the weights should be inversely proportional to the error in the sensing information. However, previous cooperative sensor fusion approaches for autonomous vehicles use a fixed error model, in which the covariance of a sensor and its recognizer pipeline is just the mean of the measured covariance for all sensing scenarios. The approach proposed in this paper estimates error using key predictor terms that have high correlation with sensing and localization accuracy for accurate covariance estimation of each sensor observation. We adopt a tiered fusion model consisting of local and global sensor fusion steps. At the local fusion level, we add in a covariance generation stage using the error model for each sensor and the measured distance to generate the expected covariance matrix for each observation. At the global sensor fusion stage we add an additional stage to generate the localization covariance matrix from the key predictor term velocity and combines that with the covariance generated from the local fusion for accurate cooperative sensing. To showcase our method, we built a set of 1/10 scale model autonomous vehicles with scale accurate sensing capabilities and classified the error characteristics against a motion capture system. Results show an average and max improvement in RMSE when detecting vehicle positions of 1.42x and 1.78x respectively in a four-vehicle cooperative fusion scenario when using our error model versus a typical fixed error model

Alternative, Grassroots, And Rogue Leadership: A Case For Alternating Leaders In Organizations

The article examines traditional understanding of top-down organizational leadership against spontaneous, self-initiated leadership/followership theory. It also denotes the relationship between spontaneous and self-initiated expression of alternative, grassroots, and rogue leadership as a construct of alternating leadership behaviors. The research furthers the leadership research focus that is identified as Alternating Leadership and acknowledges leader/follower dual function within each individual. The constructs are augmented by a matrix that contrasts the strength of the leadership and followership roles among traditional versus non-traditional leadership theories. Conclusions suggest a confirmation of the dual Alternating Leadership role existing within all employees or managers and the creation of worker-centered, real-time interventions to increase employee interaction and synergy. The impact of generational leadership on the Alternating Leadership Model is also examined

Use of Grasses and Mixtures of Grasses for Energy Purposes

As levels of agricultural productivity increase, there is also an increase in land area not utilized for food production. This area can be used for growing energy crops, including grasses. When land is set aside for grassing, or when the potential of perennial grasses is not utilized due to reductions in cattle herds, there is also an increased amount of grass that can be utilized for energy purposes. Experiments were carried out on the principle of single-stage anaerobic digestion within the mezophyle range. During the experiments, we measured the cumulative production of biogas and its composition. The processed grass was disintegrated by pressing and cutting. This adaptation of the material resulted in increased biogas production. The optimum proportion of grass dry matter is from 35 to 50 % in the total d.m. The results of the experiments proved the suitability of grass phytomass as a material for biogas production