Robot Excitation Trajectories for Dynamic Parameter Estimation using Optimized B-Splines

In this paper we adressed the problem of finding exciting trajectories for the identification of manipulator link inertia parameters. This can be formulated as a constraint nonlinear optimization problem. The new approach in the presented method is the parameterization of the trajectories with optimized B-splines. Experiments are carried out on a 7 joint Light-Weight robot with torque sensoring in each joint. Thus, unmodeled joint friction and noisy motor current measurements must not be taken into account. The estimated dynamic model is verified on a different validation trajectory. The results show a clear improvement of the estimated dynamic model compared to a CAD-valued model

Modeling of Turbulent Boundary Layer Surface Pressure Fluctuation Auto and Cross Spectra - Verification and Adjustments Based on TU-144LL Data

The literature on turbulent boundary layer pressure fluctuations provides several empirical models which were compared to the measured TU-144 data. The Efimtsov model showed the best agreement. Adjustments were made to improve its agreement further, consisting of the addition of a broad band peak in the mid frequencies, and a minor modification to the high frequency rolloff. The adjusted Efimtsov predicted and measured results are compared for both subsonic and supersonic flight conditions. Measurements in the forward and middle portions of the fuselage have better agreement with the model than those from the aft portion. For High Speed Civil Transport supersonic cruise, interior levels predicted by use of this model are expected to increase by 1-3 dB due to the adjustments to the Efimtsov model. The space-time cross-correlations and cross-spectra of the fluctuating surface pressure were also investigated. This analysis is an important ingredient in structural acoustic models of aircraft interior noise. Once again the measured data were compared to the predicted levels from the Efimtsov model

Comparing a microbial biocide and chlorine as zebra mussel control strategies in an Irish drinking water treatment plant

A need exists for an environmentally friendly mussel control method to replace chlorine and other traditional control methods currentlyutilised in drinking water plants and other infested facilities. Zequanox® is a newly commercialised microbial biocide for zebra and quaggamussels comprised of killed Pseudomonas fluorescens CL145A cells. The objective of this study was to compare the efficacy of adevelopmental formulation of Zequanox (referred to as MBI 401 FDP) and chlorine treatments on adult and juvenile zebra mussels byrunning a biobox trial in conjunction with chlorine treatments at an infested Irish drinking water treatment plant. Since 2009, the plantmanagement has used a residual chlorine concentration of 2 mg/L in autumn to control both adult zebra mussels and juvenile settlement intheir three concrete raw water chambers. Juvenile mussel settlement was monitored in three bioboxes as well as in three treatment chambersin the plant for three months prior to treatment. Adult mussels were seeded into the chambers and bioboxes four days before treatment. InOctober 2011, the bioboxes were treated with MBI 401 FDP at 200 mg active substance/L, while chlorine treatment took place in the waterchambers. The MBI 401 FDP treatment lasted only 8 hours while chlorine treatment lasted seven days. Juvenile numbers were reduced tozero in both the bioboxes and treated chambers within seven days. Adult mussel mortality reached 80% for both the chlorine and MBI 401FDP treatment; however, mortality was achieved faster in the chlorine treatment. These results provided important insights into zebra musselcontrol alternatives to chlorine and supported further development of the now commercial product, Zequanox

Visible light photoredox catalyzed deoxygenations and polymer-tagged photocatalysts

This thesis starts with a brief introduction to visible light mediated photoredox catalysis. Therefore underlying photo-physical processes are presented followed by showcasing of two very recent, trendsetting publications in the area. Within the chapter “Photochemical Deoxygenations” research results concerning photochemical C–O bond scission reactions are detailed. Preliminary studies with phosphonate esters as activation groups for C–O bonds led to the employment of 3,5-bis(trifluoromethyl)benzoates as activating unit. After optimization of the reaction conditions and discussion of the reaction mechanism the substrate scope and limitations of the process are shown. Subsequently experiments towards an in situ activation of alcohols followed by performance of the photochemical reaction step in continuous flow are described. The following section deals with the expansion of the developed photochemical C–O bond fragmentation reactions towards the formation of new C–C bonds. After efforts to use unactivated alcohol derivatives in intramolecular cyclizations and activated alcohol derivatives in intermolecular bond formations prove to be unfruitful, intramolecular cyclizations from activated benzoates leading to chiral tetrahydrofuran derivatives are realized. The synthesis of suitable substrates and their photochemical performance is evaluated. The chapter “Polymer-tagged Photocatalysts” deals with the immobilization of iridium-based photocatalysts with homogeneously soluble polymers and their recycling. Studies with biscyclometalated iridium complexes result in an easily recyclable derivative of [Ir(ppy)2(dtb-bpy]+. Its application in the decarboxylative synthesis of isoquinolinones with visible light is investigated. Optimization of the catalyst design and streamlining of the synthesis are shown. In the second part of the chapter a triscyclometalated iridium complex is synthesized and repeatedly used for photoredox reactions in a batch process. Experiments towards automatic catalyst recovery and reusage in a continuously operating microreactor setup for photoreactions complete the investigations with polymer-tagged photocatalysts

Calibration of linear contact stiffnesses in discrete element models using a hybrid analytical-computational framework

Efficient selections of particle-scale contact parameters in discrete element modelling remain an open question. The aim of this study is to provide a hybrid calibration framework to estimate linear contact stiffnesses (normal and tangential) for both two-dimensional and three-dimensional simulations. Analytical formulas linking macroscopic parameters (Young's modulus, Poisson's ratio) to mesoscopic particle parameters for granular systems are derived based on statistically isotropic packings under small-strain isotropic stress conditions. By taking the derived analytical solutions as initial approximations, the gradient descent algorithm automatically obtains a reliable numerical estimation. The proposed framework is validated with several numerical cases including randomly distributed monodisperse and polydisperse packings. The results show that this hybrid method practically reduces the time for artificial trials and errors to obtain reasonable stiffness parameters. The proposed framework can be extended to other parameter calibration problems in DEM

On the challenges facing the handling of solid biomass feedstocks

With a major global emphasis on the management of waste, alternative resources and a shift to environmentally sustainable technologies, demand for large volumes of heterogeneous solid biomass feedstocks for energy or chemical use is expected to rise significantly. In transforming a sporadic supply of a low-value, highly variable product, to continuous and controlled high through-put systems, a thorough understanding of the feedstock properties will increase in importance. Appropriate characterisation tests are necessary to define technical specification and selection criteria for handling equipment and to appraise the requirement and location for additional processes or pre-treatment to be integrated into the handling chain. Such tests may also influence the material characteristics to be used in the conversion process. This paper discusses the main feedstock attributes associated with a number of handling chain phases and the approach to obtain them. The framework for a holistic approach to the characterisation and design of biomass feedstock handling systems for further development and practical implementation is also proposed