Journal: Procedia Engineering

Abbreviation

Publisher

Elsevier

Journal Volumes

ISSN

Description

Filters

2010 - 201850
Reset filters

Search Results

Publications 1 - 10 of 50
  • Microfluidic cell culturing platform combining long-term, high-resolution imaging with impedance spectroscopy
    Item type: Conference Paper
    Chawla, Ketki; Bürgel, Sebastian C.; Schmidt, Gregor W.; et al. (2015)
    Procedia Engineering ~ Eurosensors 2015
    We present an integrated microfluidic system, which combines long-term cell culturing with electrical impedance spectroscopy (EIS) on a single chip. Non-adherent cells, such as yeast (S. cerevisiae), can be grown under constant media perfusion in a 2D layer under clamping pads that enable long-term time-lapse microscopy within the same focal plane. The addition of EIS provides a complementary method for continuous in-situ analysis of single cells and has been used here to monitor the growth rate of cell colonies in real time.
  • Active vibration control of lightweight floor systems
    Item type: Conference Paper
    Baader, Jakob; Fontana, Mario (2017)
    Procedia Engineering ~ X International Conference on Structural Dynamics, EURODYN 2017
    Long-span and lightweight floors are often prone to structural vibrations due to their low resonance frequency and inherent damping. They are easily excited by human walking or running and present a serviceability problem for persons working or living in these buildings. Tuned mass dampers can be used to improve the dynamic behaviour of such structures. The drawback of these passive damping systems is that they require high inertial damper masses and that the damping efficiency in transient phase is low. Especially for systems with resonance frequencies that change over time (due to an addition mass or a change of the structure or temperature dependant phenomena) the damping efficiency drops rapidly. Active controlled tuned mass damper can be used to reduce the inertial mass and improve the damping efficiency for a broad band of frequencies in transient phase. Several constraints, like the stability in closed loop, robustness and performance criteria and the maximum stroke and saturation of the actuator have to be considered when designing a controller for an active vibration control device. Different control strategies are analysed in this work and simulated using a 2nd and a 4th order system in order to analyse advantages and drawbacks.
  • An array of 2D Magnetic Micro Force Sensors for Life Science Applications
    Item type: Conference Paper
    Praprotnik, Jan; Ergeneman, Olgaç; Chatzipirpiridis, George; et al. (2015)
    Procedia Engineering ~ Eurosensors 2015
    This paper reports a 2D magnetic micro force sensor. The design consists of an array of SU-8 cantilevers incorporating electroplated ferromagnetic material and a Hall sensor array. The passive moving parts with magnetic readout enable robust and sensitive operation. The presented device has a detection limit of 30 μN and a range up to 1 mN. A not well-known material in MEMS community polyurethane was used as a protection layer encapsulating the whole device while interfering minimally with the operation. Cantilevers were characterized for their dynamic response by a laser Doppler vibrometer and 2D force calibration is performed using commercial force sensors. The presented sensor array can be used in life science applications and MEMS testing enabling parallel measurements in 2-D.
  • Experimental and analytical investigation of the inelastic behavior of structures isolated using friction pendulum bearings
    Item type: Conference Paper
    Tsiavos, Anastasios; Schlatter, David; Markic, Tomislav; et al. (2017)
    Procedia Engineering ~ X International Conference on Structural Dynamics, EURODYN 2017
    Current American and European code provisions prohibit yielding of base-isolated structures. Therefore, the majority ofexisting base-isolated structures are designed elastically. This study aims at investigating the necessity of the elastic design of thesestructures through the analytical and experimental investigation of their inelastic behavior.This analytical investigation is performed using a two-degree-of-freedom model of a base-isolated structure. The bilinearhysteretic behavior of the structure and the isolator is simulated via a Bouc-Wen model. Numerous simulations of the response tostrong ground motion excitations were performed using Matlab and Opensees models.The experimental investigation performed in this study is based on the response of a reduced-scale base-isolated steel structureto strong recorded ground motion accelerations applied using the shaking table of the IBK Structural Testing laboratory of ETHZurich. The part of the structure designed to develop inelastic behavior is a pair of steel coupons that can be easily replaced aftersuch damage. The structure is base-isolated using four friction pendulum bearings provided by MAGEBA.The experimentally observed inelastic behavior of base-isolated structures is compared to the analytically simulated behavior.A relation between experimentally obtained strength and displacement ductility of these structures is presented. The influence of awide range of response parameters is quantified and presented. The experimentally obtained data is compared to an analyticallyderived strength-ductility-period relation for seismically isolated structures. This comparison serves to validate the proposedanalytical relation and to increase the understanding of the behavior of inelastic seismically isolated structures.
  • Effect of thermal annealing on the stiffness of an SU-8 torsional spring
    Item type: Conference Paper
    Li, Yunjia; Kühne, Stéphane; Psychogiou, Dimitra; et al. (2012)
    Procedia Engineering ~ 26th European Conference on Solid-State Transducers, EUROSENSOR 2012
    The effect of thermal annealing on the torsional and bending stiffness of a polymeric torsional spring is studied, by analyzing the static and dynamic behavior of an SU-8 spring attached to the bottom of a silicon comb-drive actuator. The results suggest that, after thermal annealing, the torsional stiffness has been reduced (16.7%) while the bending stiffness has been increased, which is desirable for the operation of the spring. The phenomenon is explained by the influence of the bi-axial residual stress variation in the SU-8 spring.
  • Using a Tabu-search Algorithm and 4D Models to Improve Construction Project Schedules
    Item type: Conference Paper
    García de Soto, Borja; Rosarius, Anton; Rieger, Jochen; et al. (2017)
    Procedia Engineering ~ Creative Construction Conference 2017, CCC 2017
    Construction project managers are interested in completing their projects on time and within budget. To do that, they often develop project schedules using a set of standardized tools, such as the Program Evaluation and Review Technique (PERT), the Critical Path Method (CPM) and bar charts. Although useful, these tools offer little help regarding the spatial context (i.e., visualization of conflicts among construction activities) as well as determining the optimal schedule with respect to time, cost and resources. The considerations of these two aspects are left to expert opinion, which can sometimes lead to unexpected conflicts during construction and, in turn, result in project delays and added costs. The main steps of the methodology presented here include 1) the determination of optimal schedules using Tabu-search algorithm that accounts for single or multiple objectives (e.g., duration, costs, resources) depending on the project requirements or project management needs, and 2) the integration of project visualization (i.e., 4D models). The visualization of the optimized schedules allows the project team to check the schedule for completeness and to ensure that sequencing and constructability requirements are satisfied. During the visualization process, further refinement of the schedule can be done. The proposed methodology is demonstrated by using it to create the schedule for a one-story steel-frame building. It is shown that the presented methodology results in an improved schedule for the example project over one that may be expected to be generated without this methodology. The best improvements that could be achieve corresponded to a 13% reduction in the project duration, 4% cost reduction, and 49% decrease in resource fluctuation.
  • Stability under Seepage Flow Conditions of a Tunnel Face Reinforced by Bolts
    Item type: Conference Paper
    Perazzelli, Paolo; Cimbali, G.; Anagnostou, Georgios (2017)
    Procedia Engineering ~ ISRM European Rock Mechanics Symposium EUROCK 2017
    We propose a computational method for assessing bolt reinforcement of the tunnel face in cohesive frictional soils and weak rocks under seepage flow conditions. The method is based on limit equilibrium factors and can be applied to reinforcement layouts that are arbitrary in terms of the spacing, length, longitudinal overlapping and installation sequence of the bolts. An investigation is made into the influence of water table height on the stability of a reinforced face. In particular, we show that, if the gradient of the hydraulic head is high, then tensile failure of the ground ahead of the face may be more critical than shear failure. For an approximate hydraulic head distribution in the ground around the tunnel face and assuming uniform face reinforcement, we derive a closed-form solution for the necessary bolting density.
  • BIM-based Applications of Metaheuristic Algorithms to Support the Decision-making Process: Uses in the Planning of Construction Site Layout
    Item type: Conference Paper
    Amiri, Roya; Majrouhi Sardroud, Javad; García de Soto, Borja (2017)
    Procedia Engineering ~ Creative Construction Conference 2017, CCC 2017
    The use of Building Information Modeling (BIM) is affecting the way in which construction projects are planned, designed, executed and operated. One of the main goals of BIM is to provide, based on a 3D model, an accurate information model in a digital format to give different project participants better tools when evaluating different options to support their decisions about the project at a given phase. With this in mind, BIM provides a suitable framework to support the decision-makings process by aggregating the necessary information at the right time, and clarifying details and existing conditions; however, the different elements required to make an optimized decision need additional consideration. To address that, this paper explores the value of metaheuristic algorithms for reaching an optimized solution. The use of metaheuristic algorithms is well known in various aspects of knowledge optimization. This paper provides an overall review of the applications of metaheuristic algorithms in BIM-based optimized decisions in the construction industry and focuses on applications to the planning of construction site layout. Based on the findings from this paper, research gaps in this area have been identified and suggestions for future research to address those gaps are suggested.
  • Bandwidth Compensation for High Resolution Impedance Spectroscopy
    Item type: Conference Paper
    Haandbaek, Niels; Mathwig, K.; Streichan, Ralf; et al. (2011)
    Procedia Engineering ~ Eurosensors XXV
    This paper reports on a microfluidic differential impedance cytometer, which uses a bandwidth compensation technique together with a small detection volume and multi-frequency analysis to achieve an increased sensitivity. The bandwidth compensation technique allows for measurements within small bandwidths by accounting for the increased signal amplitude dependence on the particle speed. We demonstrate detection and clear baseline discrimination of polystyrene beads with diameters of 1 μm and 2 μm and the discrimination of 5 μm beads from yeast cells of similar size. We show that using multiple frequencies in parallel significantly improves the discrimination performance of the cytometer.
  • Suppression of cross-sensitivity to humidity in pristine, suspended single-walled nanotube NO2 sensors
    Item type: Conference Paper
    Chikkadi, Kiran; Muoth, Matthias; Beckmann, Niklas; et al. (2014)
    Procedia Engineering ~ EUROSENSORS 2014, the 28th European Conference on Solid-State Transducers
    The humidity response of pristine, suspended single-walled carbon nanotube (SWNT) gas sensors is analyzed. We employ ultraclean, dry-transferred carbon nanotubes, whose surface is not exposed to any resist-based or wet-chemical processes. Thanks to this, the nanotube surface remains pristine before gas exposure. The sensor response to NO2 follows a Langmuir isotherm. No cross-sensitivity to water up to 60% R.H. is observed, and the device remains sensitive to NO2 with no apparent degradation of the response.
Publications 1 - 10 of 50