Development Laboratories

Eindhoven, Netherlands

Development Laboratories

Eindhoven, Netherlands

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Peters H.J.,Technical University of Delft | Peters H.J.,Development Laboratories | Goosen J.F.L.,Technical University of Delft | Van Keulen F.,Technical University of Delft
International Journal of Micro Air Vehicles | Year: 2015

Energy-effective hovering and active flight control are of paramount importance for the usefulness of Flapping Wing Micro Air Vehicles (FWMAVs). Recent studies have focused on separate parts (e.g., wing planform design, wing kinematics, or flight control) rather than on the complete system. This work presents a combined approach to find an optimal wing design (i.e., wing planform and pitching kinematics) for energy-effective hovering and roll control. Relatively simple mathematical descriptions are used for the kinematics, the aerodynamics and the roll motion to allow its use in optimization techniques. Results show that the wing design depends significantly on the relative importance of either energy-effective hovering or effective roll control during the optimization. The roll control effectiveness increases if the wing area around the wingtip is increased to push the center of lift outwards. Additionally, we show that the most effective control variable, to enforce the required body moment for the roll motion, depends strongly on the wing design. In conclusion, flapping wing design requires, in general, a combined approach to guarantee both energy-effective hovering and effective roll control. © 2015, Multi-Science Publishing Co. Ltd. All rights reserved.


Peters H.J.,Technical University of Delft | Peters H.J.,Development Laboratories | Tiso P.,Technical University of Delft | Goosen J.F.L.,Technical University of Delft | Van Keulen F.,Technical University of Delft
11th World Congress on Computational Mechanics, WCCM 2014, 5th European Conference on Computational Mechanics, ECCM 2014 and 6th European Conference on Computational Fluid Dynamics, ECFD 2014 | Year: 2014

Several Flapping Wing Micro Air Vehicle (FWMAV) designs exploit structural resonance to decrease power consumption. Practical use of most resonating structures requires temporary modifications to the resonance mode (i.e., the eigensolution). This paper presents a systematic design approach to modify non-proportionally damped resonance modes in a desired way while consuming minimal control power. These modifications are induced by local structural changes. Eigensolution sensitivities in the modal basis are used to linearly approximate the effect of these changes on the resonance mode. Results show that the interpretation of resonance mode changes is highly clarified by introducing the modulus (magnitude) and argument (phase) information of the resonance mode. The proposed projection allows the determination of the locations at which a specific structural change scores maximum effect in terms of relative magnitude and/or phase modifications. The applied modal approach reduces the size of the problem, which is advantageous during analysis. This work shows resonance mode modifications of non-proportionally damped systems due to local structural changes in a intuitive manner.


Peters H.J.,Technical University of Delft | Peters H.J.,Development Laboratories | Goosen J.F.L.,Technical University of Delft | Tiso P.,Technical University of Delft | Van Keulen F.,Technical University of Delft
Proceedings of the ECCOMAS Thematic Conference on Multibody Dynamics 2013 | Year: 2013

The motion amplitude of a harmonically driven compliant structure is maximized if the driving frequency equals one of the structural resonance frequencies. For the effective use of resonating compliant structures, control of the eigensolutions, i.e., eigenfrequencies and eigenmodes, is often required. This work shows a design methodology in which eigenproblem sensitivity is used in a systematic way to design the most effective locations to apply local structural modifications for a required change in the eigensolutions. By applying control patches at these locations the power requirements are minimized. The modal basis of the structure is used as the preferred basis which leads to valuable insights in the possibilities and limitations of controlling specific eigensolutions. The influence on the eigensolutions due to the mechanical properties of the attached inactive control actuators is separated from the influence due to the active actuation of the control actuators. Whether or not a control actuator is actively actuated depends on the desired control state. Furthermore, it is argued that nearly repeated eigenfrequencies contribute to the effective control of eigenmodes. A simple compliant structure is used to demonstrate the potential of the presented design methodology. In this example, the uncontrolled eigensolutions are forced into different, independent control states using effectively distributed control actuators.


Peters H.J.,Technical University of Delft | Peters H.J.,Development Laboratories | Tiso P.,Technical University of Delft | Goosen J.F.L.,Technical University of Delft | Van Keulen F.,Technical University of Delft
Journal of Sound and Vibration | Year: 2015

Structural resonance can be exploited to obtain a specific motion at low input power. This paper presents an approach to determine the locations, number, and dimensions of local structural changes to temporary obtain different resonance configurations while consuming minimal control power. The starting point is a non-dissipative resonance mode. Eigensolu-tion sensitivities are used to approximate the effect of the local structural changes on a given resonance mode. In order to increase insight and intuitive understanding, these sensitivities are expressed in terms of the modal basis. A projection is proposed to focus on the modifications at specific regions of interest, thus leaving the remaining portions of the mode unspecified. By expressing this projection in terms of the modal basis, the number of significant modes in the analysis decreases drastically, and the computational effort is largely reduced. Closely spaced eigenfrequencies appear to be attractive for effective resonance mode modifications. A plate example demonstrates the approach. © 2014 Elsevier Ltd. All rights reserved.


Kostewicz E.S.,Goethe University Frankfurt | Abrahamsson B.,Astrazeneca | Brewster M.,Drug Product Development | Brouwers J.,Catholic University of Leuven | And 15 more authors.
European Journal of Pharmaceutical Sciences | Year: 2014

Accurate prediction of the in vivo biopharmaceutical performance of oral drug formulations is critical to efficient drug development. Traditionally, in vitro evaluation of oral drug formulations has focused on disintegration and dissolution testing for quality control (QC) purposes. The connection with in vivo biopharmaceutical performance has often been ignored. More recently, the switch to assessing drug products in a more biorelevant and mechanistic manner has advanced the understanding of drug formulation behavior. Notwithstanding this evolution, predicting the in vivo biopharmaceutical performance of formulations that rely on complex intraluminal processes (e.g. solubilization, supersaturation, precipitation...) remains extremely challenging. Concomitantly, the increasing demand for complex formulations to overcome low drug solubility or to control drug release rates urges the development of new in vitro tools. Development and optimizing innovative, predictive Oral Biopharmaceutical Tools is the main target of the OrBiTo project within the Innovative Medicines Initiative (IMI) framework. A combination of physico-chemical measurements, in vitro tests, in vivo methods, and physiology-based pharmacokinetic modeling is expected to create a unique knowledge platform, enabling the bottlenecks in drug development to be removed and the whole process of drug development to become more efficient. As part of the basis for the OrBiTo project, this review summarizes the current status of predictive in vitro assessment tools for formulation behavior. Both pharmacopoeia-listed apparatus and more advanced tools are discussed. Special attention is paid to major issues limiting the predictive power of traditional tools, including the simulation of dynamic changes in gastrointestinal conditions, the adequate reproduction of gastrointestinal motility, the simulation of supersaturation and precipitation, and the implementation of the solubility-permeability interplay. It is anticipated that the innovative in vitro biopharmaceutical tools arising from the OrBiTo project will lead to improved predictions for in vivo behavior of drug formulations in the GI tract. © 2013 Elsevier B.V. All rights reserved.


Peters H.J.,Technical University of Delft | Peters H.J.,Development Laboratories | Goosen J.F.L.,Technical University of Delft | Keulen F.V.,Technical University of Delft
Smart Materials and Structures | Year: 2016

Lightweight vibrating structures (such as flapping wing micro air vehicle (FWMAV) designs) often require some form of control. To achieve controllability, local structural property changes (e.g., damping and stiffness changes) might be induced in an active manner. The stroke-averaged lift force production of a FWMAV wing can be modified by changing the structural properties of that wing at carefully selected places (e.g., changing the properties of the elastic hinge at the wing root as studied in this work). To actively change the structural properties, we investigate three different methods which are based on: (1) piezoelectric polymers, (2) electrorheological fluids, and (3) electrostatic softening. This work aims to gain simple yet insightful ways to determine the potential of these methods without focusing on the precise modeling. Analytical models of FWMAV wing designs that include control approaches based on these three methods are used to calculate the achievable lift force modifications after activating these methods. The lift force production as a result of a wing flapping motion is determined using a quasi-steady aerodynamic model. Both piezoelectric polymers and electrostatic softening are found to be promising in changing the structural properties and, hence, the lift force production of FWMAV wings. For the control of lightweight FWMAV designs, numerical simulations reveal a promising roll maneuverability due to the induced lift force difference between a pair of opposite wings. Although applied to a specific FWMAV design, this work is relevant for control of small, lightweight, possible compliant, vibrating structures in general. © 2016 IOP Publishing Ltd.


Peters H.J.,Technical University of Delft | Peters H.J.,Development Laboratories | Tiso P.,Technical University of Delft | Goosen J.F.L.,Technical University of Delft | Van Keulen F.,Technical University of Delft
IFASD 2013 - International Forum on Aeroelasticity and Structural Dynamics | Year: 2013

Several Flapping Wing Micro Air Vehicle (FWMAV) designs use structural resonating properties to increase energy efficiency. For practical use, control of the resonating structure, i.e., the eigensolutions, is required which is complicated by constraints on weight and power consumption. Hence, systematic ways to induce substantial changes in the resonance response are of high interest. Eigensolution sensitivity is used to approximate the change in the resonance vibration, i.e., the eigenmode, due to local structural modifications. Expressing these sensitivities in a modal basis, shows that (nearly) repeated eigenvalues are an indication for effective eigenmode control. The eigenmodes corresponding to repeated eigenvalues are not uniquely defined but any linear combination of these eigenmodes is also an eigenmode. This could lead to substantial changes in the eigenmode, or vibration response, if the eigenmodes become uniquely defined again if the corresponding eigenvalues become distinct due to local structural modifications. A smart structural design could use this idea to exhibit substantial changes in the eigenmodes as introduced by relatively limited control action. The response of a simple symmetric structure, with repeated eigenvalues, shows the response change if the structure becomes asymmetric. Additionally, the influence of structural damping on the effectiveness of the response change is shown.


Lalloo A.K.,Merck And Co. | McConnell E.L.,Development Laboratories | Jin L.,Merck And Co. | Elkes R.,Development Laboratories | And 2 more authors.
International Journal of Pharmaceutics | Year: 2012

Gastric retention is postulated as an approach to improve bioavailability of compounds with narrow absorption windows. To elucidate the role of image size on gastric retention and pharmacokinetics, formulations with different image sizes and swelling kinetics but similar dissolution rates were designed and imaged in dogs. Diet had a clear effect, with increasing calorific intake prolonging retention in the dog model. In contrast to clinical observations, no obvious effect of image size on gastric retention was observed in the dog, with the larger gastric retentive (GR) and smaller controlled release (CR) formulations both demonstrating similar gastric emptying. Comparable pharmacokinetic profiles were observed for the two formulations, corroborating the imaging data and providing evidence of similar in vivo dissolution rates and dosage form integrity in the dog. Food, specifically meal composition, resulted in comparable enhancements in exposure in the dog and clinic due to prolonged gastric retention. However, differentiating retention based on image size in the dog was not feasible due to the smaller pyloric aperture compared to humans. This work illustrates that the dog is capable of determining the pharmacokinetic advantage of gastric retention relative to immediate release (IR) or CR formulations, however, has limited value in differentiating between CR and GR formulations. © 2012 Elsevier B.V. All rights reserved.


Peters H.J.,Technical University of Delft | Peters H.J.,Development Laboratories | Tiso P.,Technical University of Delft | Goosen J.F.L.,Technical University of Delft | Van Keulen F.,Technical University of Delft
ECCOMAS Thematic Conference - COMPDYN 2013: 4th International Conference on Computational Methods in Structural Dynamics and Earthquake Engineering, Proceedings - An IACM Special Interest Conference | Year: 2013

The motion amplitude of a harmonically driven compliant structure is maximized if the driving frequency equals one of the structural resonance frequencies. For practical use of resonating compliant structures control of the eigensolutions, i.e. eigenfrequencies and eigenmodes, is often required. In this work, a systematic way to control the eigensolutions of harmonically driven structures is presented while maintaining the advantages of a resonating structure. This control is realized using local structural modifications. Eigensolution sensitivities for these local structural modifications are used to indicate the locations for the most effective structural modifications, minimizing the required control power. This method uses the modal basis of the structure as the preferred basis. A simple harmonically driven compliant structure is used to show how local structural modifications are selected to obtain a desired change in the eigensolutions. The proposed method is found to be a convenient tool to determine effective local structural modifications to control the eigensolutions of resonating compliant structures. During the design phase it provides valuable insights in the possibilities and limitations of controlling specific eigensolutions.


PubMed | Development Laboratories
Type: Journal Article | Journal: European journal of pharmaceutical sciences : official journal of the European Federation for Pharmaceutical Sciences | Year: 2013

The present work explores the application of in situ near infrared (NIR) imaging to determine the drug release mechanisms from hydrophilic matrices containing a low solubility model drug (Compound A, with aqueous solubility at 37C 0.05 mg/mL). Correlation maps generated from the NIR data determined the extent drug and HPMC co-localisation. Judicious thresholding facilitated band separation of low drug/HPMC ratio and high drug/HPMC ratio. A pseudo-image time-series confirmed the dominant erosion release mechanisms. The gel layer region showed low drug concentration with progressive dissolution. However, large drug aggregates remained unchanged even when fully immersed within the gel layer. From the correlation maps, further discrimination was possible for the pure drug signal, generating a highly contrasted image that enabled individual particle tracking. These contrasted images also revealed the evolution of single or clusters of drug particles. Initially, an aggregative process involving the drug particles occurred, with a subsequent migration process of such particles. This second process dominated the subsequent 90 min before significant erosion. In summary, this study has provided tentative confirmation that NIR imaging has the potential to afford insights into drug liberation phenomena where erosion is the predominant release mechanism.

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