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Benzoic acid esterases and ferulic acid esterases (FAE) are enzymes with different profiles of substrate specificity. An extracellular esterase (EstBC) from culture supernatants of the edible basidiomycete fungus Auricularia auricula-judae was purified by anion exchange chromatography, followed by preparative isoelectric focusing and hydrophobic interaction chromatography. EstBC showed a molecular mass of 36 kDa and an isoelectric point of 3.2 along with broad pH and temperature windows similar to fungal FAEs. However, EstBC exhibited also characteristics of a benzoic acid esterase acting on both benzoates and cinnamates, and most efficiently on methyl and ethyl benzoate, methyl 3-hydroxybenzoate and methyl salicylate. Feruloyl saccharides as well as lipase substrates, such as long chain fatty acids esterified with glycerol, polyethoxylated sorbitan and p -nitrophenol were not hydrolyzed. Protein database analyses with tryptic peptides of EstBC solely yielded hits regarding hypothetical proteins belonging to the alpha/beta hydrolase family. The uncommon substrate specificity of EstBC concomitant with a lack of sequence homology to known enzymes suggests a new type of enzyme.

The paper describes the addition of actively controlled aerodynamic appendages (flaps) attached along the length of the bridge deck to dampen wind-induced oscillations in long suspension bridges. A novel approach using control systems methods for the analysis of dynamic stability is presented. In order to make use of control analysis and design techniques, a linear model of the structural and aerodynamic motion around equilibrium is developed. The model is validated through comparison with finite element calculations and wind tunnel experimental data on the Great Belt East Bridge in Denmark. The developed active control scheme is local in that the flap control signal at a given longitudinal position along the bridge only depends on local motion measurements. The analysis makes use of the Nyquist stability criteria and an analysis of the sensitivity function for stability analysis. The analysis shows that the critical wind speed for flutter instability and divergence is increased substantially by active control.

This paper describes a control method for non-linear systems based on generalized predictive control. Generalized predictive control (GPC) was developed to control linear systems, including open-loop unstable and non-minimum phase systems, but has also been proposed to be extended for the control of non-linear systems. GPC is model based and in this paper we propose the use of a neural network for the modeling of the system. Based on the neural network model, a controller with extended control horizon is developed and the implementation issues are discussed, with particular emphasis on an efficient quasi-Newton algorithm. The performance is demonstrated on a pneumatic servo system.

The possibilities of implementing an active boom suspension is investigated. Compared with a traditional passive suspension, it could improve the spraying result, and make the operators task much easier. In a simulation is compared the possible performance of both an active and a passive system. The simulated passive suspension is an advanced construction, that combines a traditional trapezoid with a spring pendulum system. The active suspension is combining a hydraulic actuator and a spring. According to the simulations, the performance is improved significantly. An attempt has been made to implement the active suspension on a full-size field sprayerboom provided with the hydraulics of a running tractor. A closed loop controlsystem with two ultrasonic sensors, a proportional valve and a hydraulic actuator has been constructed. In the article is described how the system has been build, and what changes should be made for future experiments.

A very fast digital control system implemented with a AT&T signalprocessor DSP32 which has been developed to the fast TUD-hydraulic test robot manipulator installed in the hydraulic laboratory at the Control Engineering Institute, the Technical University of Denmark (TUD) is presented. Results and experiences with CAD/CAE-based tools for design and implementation of digital controller algorithms for hydraulic robot manipulators and other multiaxes hydraulic machines are presented and discussed. Furthermore, a new design concept applying the AT&T-signal processor DSP32C is discussed. Finally, the paper describes and discusses the simulation results with an adaptive perturbation control scheme and the obtained experimental results with a digital PID controller.

The paper describes a very fast digitally controlled hydraulic test robot manipulator which has been developed and designed by the use of CAD/CAE-methods. The robot is implemented in the hydraulic laboratory at the Control Engineering Institute, the Technical University of Denmark. The purpose of the test robot manipulator is to carry out research activities within CAD/CAE in hydraulic control system design, digital control and adaptive control design and implementation. Furthermore the test robot is used for test and evaluation of off-line and on-line systemidentification methods and digital algorithms for modelling and adaptive control of multivariable hydraulic systems such as hydraulic robots, escavators og multi-axes test equipment. The paper describes and discusses the control and mechanical design problem and CAD/CAE-methods. The special software package KISMET and ROBCAD can be used in the design and 3D-animation of the robot manipulator for investigation of the robot and the workspace. The control design of the digital control system is done with the packages MATLAB and ACSL. The digital control computer is implemented with a fast AT&T-signalprocessor. A developed adaptive geometrical compensation control scheme is proposed for control of hydraulic robot manipulators

A fast digitally controlled hydraulic test robot has been developed, designed and implemented in the hydraulic laboratory at the Control Engineering Institute, the Technical University of Denmark. The purpose of the test robot is to carry out research activities in hydraulic control system design, digital control and adaptive control and on-line systemidentification. The paper describes the test robot, design and implementation of an adaptive controller. An adaptive geometrical compensation control scheme is proposed for hydraulic robot manipulators.

In this paper an experimental system for identifying reliable and accurate steady-state characteristics of hydrostatic machines for hydraulic drives is presented. The core of the experimental system consists of two unique components: A servo controlled dynamometer for 4-quadrant operational modes and a servo controlled volume rate flowmeter. Both components have been developed at the Technical University of Denmark. First, a short review of the state-of-the-art and a discussion of analytical and experimental modelling of the steady-state characteristics for hydraulic motors and pumps are given. Then the concept, control and implementation of the developed dynamometer system are described. Further, the flowmeter principle is explained and its specifications are stated. Finally, a typical result obtained by the experimental system is presented.