bluuebunny/crossref_metadata_2025 huggingface dataset:
New Designs of Industrial Accumulators for Elastic Webs: Structures Comparison
Authors: Kuhm David , Knittel Dominique
Published: December 2013

Accumulators are used in industrial elastic web processing plant such as paper, mills, fabric, rolling mills, to permit rewind or unwind core changes while the process continues at a constant velocity. The objective is to maintain constant web line velocity and tension into and downstream the accumulator. This paper presents a summarize of nonlinear models of different classical industrial accumulator structures: one with a pneumatic actuated carriage and one with a motorized carriage. These models are derived from physical laws that describe web tension and velocity dynamics in each web span. A second part presents new accumulator structures enabling performances improvement, considering the accumulator output web tension. Finally, the last part of this paper compares, by simulations in Matlab/Simulink software environment and using performances criteria, the performances of optimized accumulators and classical industrial ones.
Design of a Spatial Aid for Communication in Robotic Surgery
Authors: Cunningham Stacey , Chellali Amine , Banez Jose , Cao Caroline G. L.
Published: December 2013

Robots are increasingly being incorporated into the clinical environment. In minimally invasive surgery, robots are used to hold the tools and camera at the operating table while the surgeon performs surgery at a console away from the rest of the surgical team, reducing the opportunity for face-to-face communication. As surgery is a team-oriented process in which surgeons, nurses, and anesthesiologists collaborate to achieve the common goal of delivering care to a patient, any barrier to communication can inhibit the team process required in surgery. This study examined surgeon-nurse spatial communication in a collaborative surgical task in a controlled experiment. It was hypothesized that providing a spatial communication aid would improve performance time and reduce the amount of communication needed for the task. Fifteen dyads of surgeons or novices completed a simulated organ manipulation task using a laparoscopic trainer box in two viewing conditions: aligned (0°) and rotated (90°) camera view. Subjects were divided into 3 experimental groups: control, cardinal directional aid, and grid directional aid. Results show that experts were faster than novices, and the directional aids significantly facilitated task performance. While the volume of communication was not different across the three groups, there was a shift toward a more collaborative style of communication in the cardinal directions and grid conditions. The findings suggest that spatial communication aids can improve performance and promote collaboration in the robotic operating room.
Microthermocouples Sensors for Velocity and Temperature Measurements in Gas Flow
Authors: Lanzetta François , Gavignet Eric , Amrane Sofiane , Baucour Philippe
Published: December 2013

This paper presents the development of two classes of sensors based on microthermocouples with different wire diameters (from 7.6 μm to 25.4 μm). The first one uses the pulsed-wire technique for the couple velocity/temperature measurement. These sensors are used with three different techniques we developed in our laboratory: the time of flight method, the oscillation frequency method and the phase method. Because the purpose of this kind of sensor is to be introduced in different microdevices, it is realized with two thermocouple wires and does not use the micromachining technologies. Its working principle is close to that of the hot wire anemometer and it presents the same advantages such as very small dimensions and weak response time. The sensor is developed in order to measure flows and temperatures in microsystems like small channels (width < 500 μm), microtubes (diameter < 53 μm) and small structures (volume < 100 μm3). The second class of sensors are based on the multi-wire thermocouple technique. In this paper we present a probe using two wires of same nature but different in diameter located close together at the measurement point. This probe is used to measure simultaneously the temperature and the velocity of flowing gas. Results will focus on oscillating flows of gas.
Effects of Piezoactuator Failure on Active Control of Beam Vibration
Authors: Pietrzakowski Marek
Published: December 2013

Relatively large, alternating in time, operational deformations of distributed piezoelectric actuators used in active vibration control may create a hazard of material degradation and damage of the actuator/host structure coupling. In the presented study a beam-like system with a surface mounted piezoelectric sensor/actuator pair operating in a closed loop with velocity feedback is analysed. The applied actuator is a piezoelectric fiber composite (PFC) with PZT (lead-zirconate-titanate) fibers aligned and polarized longitudinally. The uniform field method based on the rule of mixtures is used to determine the effective properties of the piezocomposite. Two types of the actuator failure are taken into account. The first relates to the edge delamination modelled as a significant reduction of the adhesive interlayer shear stiffness. The second relates to the PFC material degradation, which is regarded as a softening of the matrix material surrounding PZT fibers. It is assumed that the damaged adhesive region of the constant shear stiffness extends uniformly across the actuator from its ends to the centre. In analysis the beam is divided into sections due to its geometry, external loading and the damaged regions supposed. The governing equations of the activated beam sections are coupled equations related to the electrically induced tension/compression of the actuator and bending of the beam, respectively. The obtained steady-state solution satisfies boundary conditions and continuity conditions at the borders of the beam and the actuator sections. Results of calculations show the effects of stiffness degradation of both the bonding interlayer and the piezocomposite matrix material on the beam deflection and transmitted shear stresses. Besides, dynamic responses of the active system regarding changes of the control effectiveness are numerically investigated and discussed.
On the Thermodynamic Coupling in the Continuum Theory of Defects
Authors: Schnepp Johannes
Published: December 2013

The well established continuum theory of lattice defects is usually formulated in a three-dimensional material space. The defects are represented by differential geometric properties of the material manifold. Moving defects lead to differential geometric quantities changing with time. This motivates to augment the three space-like coordinates in the material space by a time-like coordinate to a four-dimensional manifold. The lattice vectors of a crystalline solid represent three space-like vectors in the material manifold. They can be completed to a tetrad field by a fourth time-like vector. The additional components of the tetrad are related to temperature and heat flux. The derivatives of the Lagrangian density for a hyper-elastic solid with respect to the components of the tetrad can be arranged in a four-dimensional second-order tensor in which entropy density and current are coupled to material momentum. The representation of entropy production leads to a Cattaneo type constitutive equation for heat transfer.
Thermodynamic Analysis and Performance Investigation of an Alpha-Type Stirling Engine
Authors: Rogdakis E. D. , Koronaki I. P. , Antonakos G. D.
Published: December 2013

The Stirling engine, as an external combustion engine, can be powered using a variety of heat sources including the continuous combustion process thus achieving significantly reduced emissions. Energy systems powered by a Stirling engines meet the needs of various applications not only in the domestic and industrial sections but in military and space gadgets as well. Stirling engines can also be used as cryocoolers in medical applications where they are called to achieve very low temperatures. Each energy system using Stirling Engine optimizes its performance in specific operating conditions. The system capacity depends on the geometric and structural characteristics, the design of the unit, the environment in which the engine is allowed to it works as well as the size of the load. In order to study the function and the efficiency of Stirling energy systems a CHP SOLO 161V -ALPHA TYPE STIRLING ENGINE was installed in the Laboratory of Applied Thermodynamics of NTUA. A thermodynamic analysis has been conducted using appropriate computing codes. The effect of each independent variable on the system performance was investigated. The study was divided into distinct levels of detail, bringing out each variable. Initially, the performance of the heat engine was examined assuming an ideal regenerator. Then, the effectiveness of the regenerator was evaluated as well as its effect on the engine performance, while the effect of the pressure drop and the energy dissipation on the engine efficiency was also investigated. Measurements were conducted using different operational conditions concerning the heating load of the engine. The effect of the geometrical characteristics of the regenerator on power output and engine performance was examined based on the results of a simulation analysis. Moreover, the power output and the efficiency of the machine in relation to the thermal load of the unit and the average pressure of the working medium were investigated. Major performance input characters affecting geometrical and operational parameters of the unit were identified leading to unit optimization with specific combinations leading to increased system performance. Simulation results were validated by comparison to corresponding values obtained by relative experiments conducted with the SOLO unit. Finally, a sensitivity analysis was performed in order to investigate the effect of the operating conditions on the performance of an alpha type Stirling Engine.
Eco-Driving Assistance System: A New Way of How to Save Energy
Authors: Nouveliere Lydie , Luu Hong-Tu , Mammar Saïd , Cheng Qi , Orfila Olivier
Published: December 2013

The work developed in this paper is realized within the ecoDriver EU FP7 project that is shortly presented in the first part of the paper. Among the several main objectives underlined by this project, one consists in developing a vehicle and energy consumption model to be validated and then used to help the driver to better drive in terms of consumption and safety, advised by a HMI (Human-Machine Interface) module. Several experimental results are shown to illustrate the obtained energy saving with such an EDAS and the legal speed respect.
Structure Design of Energy Harvester for Supporting Paroxysmal Energy Collection
Authors: Zhu Zhenhuan , Oyadiji S. Olutunde
Published: December 2013

This paper proposes a structure of energy harvester that is used to scavenge environment energy to power wireless sensor nodes. The ambient energy usually is from sunlight, wind, vibration, and so on. As the size of a sensor node is limited, the energy converted is normally small and has a prodigious random fluctuation. In order to improve the conversion efficiency of energy harvester, the paper proposes a power conversion circuit to collect rapidly paroxysmal energy generated by external environment. The circuit, as a power conditioner, bridges between energy transducers and the load of a wireless sensor node, and the power output of transducers are either AC or DC. The power conditioner implements AC-DC conversion, voltage adjusting and energy storage. A design model is developed to describe the dynamic behavior of the power conditioner under the different excitation from ambient energy sources, and energy conversion efficiency can be evaluated with the model. The proposed system architecture can be applied in the design of solar, wind or stochastic vibration energy harvesters.
Behavior Identification for Wheelchair Driver Using the Fuzzy C-Means Classification Method
Authors: Gacem A. , Nadjar-Gauthier N. , Monacelli E. , Al-ani T. , Oussar Y.
Published: December 2013

This study deals with behavior identification of Electric-Powered Wheelchair (EPW) drivers. User’s actions on the joystick determine this behavior. We assume that a driver evaluation can be performed using reference behaviors which are determined a priori. This study was carried out with two valid populations. The first one includes eight experimented subjects. The second includes six novice subjects. We propose to implement the Fuzzy C-Means (FCM) classification to separate different behaviors. The FCM was applied on the experimented population in order to determine reference’s behaviors. This shows that there were basically two different behaviors. An evaluation is performed on novice users by comparing their behaviors with respect to the reference ones. The results show that this population has an erratic behavior during the learning phase. Subsequently, users converge to one of the identified reference behaviors. We also evaluated a subject who suffers from muscular dystrophy and uses an EPW in everyday life. The results show a steady driving behavior.
Model-Based Approaches to Human-Automation Systems Design
Authors: Jamieson Greg A. , Andersson Jonas , Bisantz Ann , Degani Asaf , Lind Morten
Published: December 2013

Human-automation interaction in complex systems is common, yet design for this interaction is often conducted without explicit consideration of the role of the human operator. Fortunately, there are a number of modeling frameworks proposed for supporting this design activity. However, the frameworks are often adapted from other purposes, usually applied to a limited range of problems, sometimes not fully described in the open literature, and rarely critically reviewed in a manner acceptable to proponents and critics alike. The present paper introduces a panel session wherein these proponents (and reportedly one or two critics) can engage one another on several agreed questions about such frameworks. The goal is to aid non-aligned practitioners in choosing between alternative frameworks for their human-automation interaction design challenges.
Finite Element Analysis of the Influence of the Material Constitutive Law Formulation on the Chip Formation Process During a High Speed Metal Cutting
Authors: Gavrus Adinel , Caestecker Pascal , Ragneau Eric
Published: December 2013

During the last decades, the importance of machining in manufacturing industry has required rigorous scientific studies concerning the chip formation process in order to determine optimal speeds, feeds or other technological parameters. For all types of machining including turning, milling, grinding, honing or lapping, the phenomenon of chip formation is similar in terms of the local interaction between the tool and the work piece. Because of the intensive use of CNC machine tools producing parts at ever-faster rates, it has become important to provide analysis of high speed cutting where complex loading conditions occur during the fabrication process: high gradients of the thermo-mechanical variables, strong nonlinearities of the thermo-mechanical coupling, large plastic strains, extremely high strain rates compared to that of other forming processes, important influence of the contact friction and of the microstructure evolution. Today many scientific researches are focalized on finite element analyses of the chip formation and of its morphology evolution during a high speed metals cutting process. To improve the quality of the numerical predictions, a better description of the local shear band formation is needed, using adequate rheological models. On this point of view this paper deals with the influence of the rheological behavior formulation on the morphology and geometry of the chip formation during a finite element simulation of a high speed metal cutting process. Numerical simulations of a high speed orthogonal cutting of special steels are employed to analysis the sensitivity of the numerical results describing the local cutting area with respect to different rheological laws: Norton-Hoff or Cowper-Symonds model, Johnson-Cook one or Zerilli-Armstrong formulation. To obtain a better description of the local material loadings and to take into account the important gradient of the strain rate, plastic strain and temperature values, a more adequate constitutive model is proposed by the author.
The Effect of Gas Channels-Electrode Interface Area on SOFCs Performance
Authors: Moreno-Blanco Julio C. , Elizalde-Blancas Francisco , Hernandez-Guerrero Abel , Rubio-Arana Cuauhtemoc
Published: December 2013

It is well known that the main overpotentials during the operation of a fuel cell are activation, ohmic and concentration overpotentials. In order to operate more efficiently these devices that convert the chemical energy of the fuel into electrical energy, it is necessary to reduce as much as possible the overpotentials aforementioned. Some of the components of a fuel cell are the so called current collectors. These components affect the fuel cell performance mainly by means of two overpotentials, the ohmic and concentration overpotentials. The second one, is however, affected indirectly by the current collector design, since it may only help to distribute more uniformly the gases over the electrodes. The activation overpotential is basically not affected because it is mainly related with the electrode properties such as the exchange current density. In this work, the effect of the current collectors design on the performance of planar Solid Oxide Fuel Cells (SOFCs) is assessed by means of fully three-dimensional numerical simulations by comparing the V-I and power density curves of a planar cell. The goal of this study is not to find the optimal design of the current collectors but a way in which the overpotentials relate with their design in order to propose some helpful recommendations during the design process of these fuel cell components. These recommendations may lead to design an improved or optimal flow distributor.
Elastoplastic Nonlocal Micromorphic Formulations With Damage Gradient
Authors: Hamed M. , Saanouni K.
Published: December 2013

It is well known that the use of inelastic constitutive equations accounting for induced softening leads to pathological space (mesh) and time discretization dependency of the numerical solution of the Initial and Boundary value Problem (IBVP). To solve this drawback a thermodynamically-consistent formulation incorporating first gradient of micromorphic damage in the framework of micromorphic continuum is proposed. In this formulation the damage field is strongly coupled with mixed isotropic and kinematic nonlinear hardening together with micromorphic damage variables. A new finite element with one additional degree of freedom for the micromorphic damage field is developed and implemented into ABAQUS/EXPLICIT using the user’s subroutines VUEL and VUMAT. For the validation purpose, 3D uniaxial tension example of metallic sheet is performed using the proposed micromorphic fully coupled elastoplastic constitutive equations.
Modelling of Tubes Magnetic Pulse Welding
Authors: Guglielmetti A. , Buiron N. , Marceau D. , Rachik M. , Volat C.
Published: December 2013

Magnetic pulse process is used in the forming and welding processes. In order to predict the welding conditions, it is necessary to have an accurate modeling, which involves a coupling between magnetic and mechanical phenomena. In a first step, a numerical modeling of the magnetic field has been developed in the finite elements software ANSYS™, and the forces exerted on a tube have been predicted. The model has been validated by comparison with similar models. The influences of the different parameters have been studied. Then, the deformation of this tube has been predicted by a dynamical model in the finite elements software ABAQUS/Explicit™. As the tube shrinks, the mechanical and magnetic computings must be sequentially coupled in order to predict the forces exerted during the motion. Software MATLAB™ is used to couple the two models in the two softwares.
Modelling Chemical Processes in Cement Based Materials by Means of Multiphase Porous Media Mechanics
Authors: Pesavento Francesco , Gawin Dariusz , Schrefler Bernhard A. , Koniorczyk Marcin
Published: December 2013

A general approach to modelling chemical degradation processes in cement based materials, due to combined action of hygro-thermal, chemical and mechanical loads, is presented. Mechanics of multiphase porous media and damage mechanics are applied for this purpose. The mass-, energy- and momentum balance equations, and constitutive and physical relations are briefly presented, and then numerically solved with the finite element method. Several examples of the model application for analysing ions transport and degradation processes of concrete due to chemical attack of pure water, salt crystallisation and alkali-silica reaction are presented and discussed.
First Steps of Crack Initiation and Propagation in Fatigue of FCC Crystals Studied by Dislocation Dynamics
Authors: Déprés C. , Prasad Reddy G. V. , Tabourot L. , Sandhya R. , Sankaran S.
Published: December 2013

3D discrete dislocation dynamic (DDD) simulations are performed to simulate stage-I fatigue crack initiation and propagation along the surface, in the primary grain and its neighbouring grain, in 316L stainless steel. The scenario of crack propagation in primary grain and the evolution of dislocation structure ahead of crack tip are discussed, and in addition crack tip sliding displacement is estimated. Probable mechanisms of crack propagation from primary grain to neighbouring grain are evaluated. In this process, surface relief in the neighbouring-grain under the influence of crack stress field in the primary grain is studied for varying neighbouring-grain orientations. An enhanced evolution of surface extrusions in the neighbouring grain, are observed in the presence of heterogeneous stress field (i.e., in the presence of crack in the primary grain), compared to that in the case of homogeneous stress field. In addition, influence of crack stress field on prior cyclic-deformed substructure is presented.
Improving Quality of Train Interiors Through a VR-Based Participative Design Approach
Authors: Di Gironimo Giuseppe , Guida Mariano , Lanzotti Antonio , Vanacore Amalia
Published: December 2013

In this work we apply an innovative participative design approach for the quality evaluation of virtual prototypes of new industrial products (i.e. concept designs), by adopting statistical procedures and carrying out tests in an immersive VR environment. This methodology has been fully exploited through a case study concerning the choice of the optimal design for the interiors of a new regional train. Following this approach, the optimal concept design is defined at the end of a process consisting of five phases: identification of the quality elements of the concept design, classification of the quality elements, generation and quality evaluation of product concepts and, finally, definition of the optimal concept. According to the applied methodology after the identification of the customer’s needs, a structured set of quality elements has been defined and, successively, classified according to Kano’s theory. Following the approach of conjoint analysis, the design factors have been combined according to an experimental plan to form product virtual concepts. During the concepts generation phase we have explored those product architectures that integrate design characteristics correlated to the set of quality elements. The concepts have been created according to comfort, ergonomic and safety criteria. In particular we have considered the ergonomics of places and furniture dimensions, through the use of virtual manikins. The evaluation of the quality of the different concepts has been carried out in the VR laboratory (named “VRTest”) of the Competence Centre for the Qualification of Transportation Systems founded by Regione Campania according to an original statistical procedure and has involved a group of experts in train’s interiors design and a group of common users of regional trains.
Identification of a Steady-State Flow in Porous Media Using Artificial Neural Networks
Authors: Lefik Marek J. , Boso Daniela P. , Schrefler Bernhard A.
Published: December 2013

For a steady state convection problem, assuming given concentration field values in a few measurement points and hydraulic head values in the same piezometers, the source of the concentration, and its intensity are deduced using Artificial Neural Networks (ANNs). ANNs are trained with data extracted from Finite Difference (FD) solution of a classical convection problem for small Peclet number. The numerical analysis is exemplified for vanishing, homogeneous and non-homogeneous field of velocity. It is shown that the diffusivity vector can also be identified. The complexity of the problem is discussed for each studied case.
Training With Augmented Reality on Engineering Degrees
Authors: Roca González Cristina , García Domínguez Melchor , Martín-Gutierrez Jorge , Contero Manuel , Alcañiz Mariano
Published: December 2013

This paper reports about the research based on the comparison of tests about the spatial skill of engineering students from two Spanish universities before and after the performance of specific training for improving several abilities based on tasks with 3D objects visualized through augmented reality technology. The training was completed at home with 66 students as participants, considering a control group composed of 25 students from both universities. The AR system technical aspects are also described as well as the application developed. The study’s results show that students from both universities improve their spatial ability and there is no significant statistical significance between students from both universities, neither before nor after training so we may conclude that training’s effect on both universities is analogue.
Latent Heat Estimation of the Martensite Transformation Through Inverse Methods During the Hot Stamping Process
Authors: Blaise Alexandre , Bourouga Brahim , Abdulhay Bakri , Dessain Christine
Published: December 2013

In the hot stamping process, the temperature evolution drives the metallurgy, as well as the metallurgical transformation influences the temperature evolution through the exothermic nature of the austenite to martensite transformation. This heat release has already been highlighted by previous experimental work. This heat release leads to a source term in the heat equation in the blank. This source term must be quantified in order to accurately predict blank temperature evolution. Moreover, the end of the heat release corresponds to the end of the metallurgical transformation. It allows the determination of the minimum quenching time, relevant information for industry to minimize the process time.

This paper presents a method to quantify the heat released by the metallurgical transformation during the hot stamping of Usibor 1500P® ArcelorMittal steel, solving inverse conduction problems. It allows the determination of this heat release as a function of temperature or time. Then, integrating it, the latent heat of the transformation can be estimated. This can be done for different contact pressures between tool and blank. Finally, it can be linked to the martensite proportion to estimate it as a function of time or temperature and determine the Koistinen-Marburger model parameters. These results should improve the accuracy of numerical simulations of the hot stamping process.
Ecological Interface Design for Aircraft Guidance and Conflict Avoidance
Authors: van Paassen M. M. (René) , Ellerbroek Joost , Comans Jan , Borst Clark , Mulder Max
Published: December 2013

Changes in Air Traffic Management, exemplified by the NextGen and SESAR projects, intend to achieve ATM systems with a higher capacity and also higher efficiency, through more direct routing. At the same time, air traffic safety should continue to increase. An important step in this process can be the partial or full transfer of responsibility for separation to the flight deck, using Airborne Separation Assurance Systems (ASAS). This paper discusses the development of interfaces for ASAS operations using Ecological Interface Design. Rather than focusing on the development and testing of the displays themselves, it addresses the parallels and differences between EID in the process control domain (from which EID originated) and EID in the air traffic domain.
VISIONAIR: A European Infrastructure to Support Research Based on Visualization and Interaction Techniques
Authors: Noël Frédéric
Published: December 2013

VISIONAIR is an acronym for “VISION Advanced Infrastructure for Research”. VISIONAIR is a European infrastructure for high level visualization facilities that is open to research communities across Europe and around the world. By integrating existing facilities, VISIONAIR creates a world-class research infrastructure for conducting state-of-the-art research, thus significantly enhancing the attractiveness and visibility of the European Research Area (ERA).

VISIONAIR allows researches into Scientific Visualization, Ultra High Definition Networks, Virtual Reality, and Augmented Collaborative Environments. VISIONAIR expects high level research inside these fields and enables new research perspectives. This paper presents the aims of VISIONAIR and analyzes some challenges and opportunities open by such an infrastructure.
Application of an Advanced GTN Model
Authors: Fansi Joseph , Habraken Anne-Marie , Balan Tudor , Lemoine Xavier , Landron Caroline , Maire Eric , Bouaziz Olivier , Ben Bettaieb Mohamed
Published: December 2013

The present contribution consists of implementing an advanced GTN damage model as a “User Material subroutine” in the Abaqus FE code. This damage model is based on specific nucleation and growth laws. This model is applied to the prediction of the damage evolution and the stress state in notched specimens made of dual phase steel. By comparing numerical predictions with experimental results based on high-resolution X-ray absorption tomography, the numerical approach was improved and validated.
Tolerance Analysis of Compliant Assemblies Using FEM Simulations and Modal Description of Shape Defects
Authors: Stricher Alain , Champaney Laurent , Thiebaut Francois , Fricero Benoit , Chevassus Nicolas
Published: December 2013

This paper propose to perform tolerance analysis on compliant structure. The objective is to limit shape defects and connection defects in accordance to mechanical criteria instead of geometrical criteria. The idea is to elaborate a finite element model of the structure and to observe the stress induced by assembling non ideal parts. Firstly, a method to take into account the stiffness variation induced by the shape defects is tested on an elementary example. Secondly this method is applied on an large structure from aeronautical industry with a lot of variability. A method is also presented to find the geometrical defects which are mostly responsible of overloading the connections.
The Galerkin Lumped Parameter Method for Thermal Problems
Authors: Bermúdez Alfredo , Pena Francisco
Published: December 2013

In this contribution, we present a method called Galerkin lumped parameter (GLP) method, as a generalization of the lumped parameter models used in engineering. This method can also be seen as a model-order reduction method. Similarities and differences are discussed. In the GLP method, introduced in [1], domain is decomposed into several sub-domains and a time-independent adapted reduced basis is calculated solving elliptic problems in each sub-domain. The method seeks a global solution in the space spanned by this basis, by solving an ordinary differential system. This approach is useful for electric motors, since the decomposition into several pieces is natural. Numerical results concerning heat equation are presented. Firstly, the comparison with an analytic solution is shown to check the implementation of the numerical algorithm. Secondly, the thermal behavior of an electric motor is simulated, assuming that the electric losses are known. A comparison with the solution obtained by the finite element method is shown.
Modal Modeling of Micro-Machining Center
Authors: Chodźko Marcin , Marchelek Krzysztof
Published: December 2013

Modeling of dynamic properties of machine tools has a significant influence on improvement of its construction. This process is extremely important when a new construction of machine tool is under development. Experimental modal analysis provides information about frequency bandwidths with significant amplitudes of resonances, damping values and mode shapes. This information can be used in FEM model updating, stability prediction or finding weak elements of the machine tool structure as well.

In the paper the modal model of prototype of the micro machining center is presented. Polymax algorithm was used to estimate the poles (frequency, damping) of modal model and modal shapes. Modal model was built on the basis of the impact test results. Methodology of conducted experimental test is presented. Tested machine tool was made of different materials (steel, aluminum, stone and others) which causes difficulties during experimental investigations. In the construction different types of guideways were implemented — rolling, slide and pneumatic ones. Maximum rotational speed of the tool is about 100 000 rev/min, so the frequency range where poles of modal model are estimated is wide (high frequencies of excitation during machining). Weight of sensors used during testing is an important issue due to a low mass of the structure. Also the excitation of the structure is troublesome because of vulnerability of precise guideways and forces sensors used in machine tool construction.

Validation of the modal model is also presented in the paper and practical problems of modal testing are discussed.
Goal-Oriented Control of Finite Element Models: Recent Advances and Performances on 3D Industrial Applications
Authors: Chamoin Ludovic , Ladevèze Pierre , Pled Florent
Published: December 2013

In this work, we present two recent developments in goal-oriented error estimation applied to finite element simulations. The first one is a non-intrusive enrichment of the adjoint solution using handbook techniques, inserting locally the (generalized) Green functions associated with the quantity of interest under study. The second one is a new bounding technique, based on homothetic domains, that is an alternative to classical Cauchy-Schwarz boundings. Technical aspects and capabilities of the resulting verification tool will be shown on 3D numerical experiments.
The Dynamics of a Bi-Stable Energy Harvester: Exploration via Slow-Fast Decomposition and Analytical Modeling
Authors: Cohen Nadav , Bucher Izhak
Published: December 2013

The paper discusses the advantages of the bi-stable energy harvester over linear oscillators in the low frequency excitation regime. When excited by low-frequency base motions, a bistable vibration-based energy harvester’s response is characterized by a combination of a slow, and a non-stationary fast component. By decomposing the response of the bi-stable system into fast and slow components, some new physical insights into the dynamical properties of the system are obtained. Properties such as mechanical frequency up-conversion, asymmetry in the bi-stable potential of the system and extraction of the backbone curve are explored. The proposed decomposition is demonstrated and explained via numerical and experimental results. A simple, approximate analytical model, for the bi-stable oscillator is proposed and its ability to detect migration towards different vibration regimes is illustrated. An expression for the power output of the harvester is derived from the analytical solution allowing us to tune the bi-stable potential towards optimum performance. The analytical model sheds light on the occurrences of bifurcations in the response of such nonlinear systems and on the optimal values of potential barrier vs. excitation levels.
An Optimal Waving Device Utilized in Micro Swimmer/Pump: Analytical, Numerical and Experimental Analysis
Authors: Setter Eyal , Bucher Izhak
Published: December 2013

This paper describes a unique non-vibratory traveling wave generator, which performs as a propulsion mechanism or pump in low Reynolds number (Re) environments, i.e. in highly viscous fluids or in micro scales. In low Re numbers the dynamics of a moving body is governed mainly by fluid drag effects, therefore mobility must rely on non-inertial, non-time reversible trajectories, e.g., traveling waves. The proposed device generates axisymmetric transverse traveling waves along an elastic cylindrical shell. The waving surface induces a vorticity and pressure fields in the adjacent fluid, which result in propagation of the swimmer opposite to the wave direction, or alternatively, in pumping fluid in the wave propagation direction. The dynamics of the mechanical multi-cam device ensures, assuming negligible friction, zero actuation shaft torque, while for non-negligible friction it is demonstrated that torque oscillations are dramatically decreased, yielding a small non-zero mean torque. These properties are achieved by choosing a specific angular phase between successive cams, so that the ratio of the number of wavelengths times a harmonic index, over the number of cams is non-integer. The effects of wave discretization on the tempo-spatial frequency content of the cylindrical envelope are also studied. The analytical analysis is accompanied by numerical examples, and demonstrated with an experimental working prototype.
Deep Structure and Smart Mechanisms: Designing Perspicacious Systems
Authors: Flach John M.
Published: December 2013

A fundamental challenge in the design of any cognitive system is to support productive thinking and efficient control. Research shows that human problem solving can be greatly enhanced using representations that reflect the deep structure of problems. Further, research on human action shows that selectively constraining degrees of freedom can improve both speed and accuracy of performance. This talk will discuss how these two insights from the basic research literature can be incorporated into work analysis and interface design to enhance performance of cognitive systems. The goal is to design interfaces so that the deep structure of the problem is well mapped to the opportunities for action. A major challenge is to operationalize the basic constructs of deep structure and smart mechanism in terms of specific work domains. Examples from the medical and aviation domains will be used to illustrate how this challenge is being met.
Exposure of Escherichia coli ATCC 12806 to Sublethal Concentrations of Food-Grade Biocides Influences Its Ability To Form Biofilm, Resistance to Antimicrobials, and Ultrastructure
Authors: Capita Rosa , Riesco-Peláez Félix , Alonso-Hernando Alicia , Alonso-Calleja Carlos
Published: December 2013

Escherichia coli
ATCC 12806 was exposed to increasing subinhibitory concentrations of three biocides widely used in food industry facilities: trisodium phosphate (TSP), sodium nitrite (SNI), and sodium hypochlorite (SHY). The cultures exhibited an acquired tolerance to biocides (especially to SNI and SHY) after exposure to such compounds.
E. coli
produced biofilms (as observed by confocal laser scanning microscopy) on polystyrene microtiter plates. Previous adaptation to SNI or SHY enhanced the formation of biofilms (with an increase in biovolume and surface coverage) both in the absence and in the presence (MIC/2) of such compounds. TSP reduced the ability of
E. coli
to produce biofilms. The concentration of suspended cells in the culture broth in contact with the polystyrene surfaces did not influence the biofilm structure. The increase in cell surface hydrophobicity (assessed by a test of microbial adhesion to solvents) after contact with SNI or SHY appeared to be associated with a strong capacity to form biofilms. Cultures exposed to biocides displayed a stable reduced susceptibility to a range of antibiotics (mainly aminoglycosides, cephalosporins, and quinolones) compared with cultures that were not exposed. SNI caused the greatest increase in resistances (14 antibiotics [48.3% of the total tested]) compared with TSP (1 antibiotic [3.4%]) and SHY (3 antibiotics [10.3%]). Adaptation to SHY involved changes in cell morphology (as observed by scanning electron microscopy) and ultrastructure (as observed by transmission electron microscopy) which allowed this bacterium to persist in the presence of severe SHY challenges. The findings of the present study suggest that the use of biocides at subinhibitory concentrations could represent a public health risk.
High Salinity Alters the Germination Behavior of Bacillus subtilis Spores with Nutrient and Nonnutrient Germinants
Authors: Nagler Katja , Setlow Peter , Li Yong-Qing , Moeller Ralf
Published: December 2013

The effect of high NaCl concentrations on nutrient and nonnutrient germination of
Bacillus subtilis
spores was systematically investigated. Under all conditions, increasing NaCl concentrations caused increasing, albeit reversible, inhibition of germination. High salinity delayed and increased the heterogeneity of germination initiation, slowed the germination kinetics of individual spores and the whole spore population, and decreased the overall germination efficiency, as observed by a variety of different analytical techniques. Germination triggered by nutrients which interact with different germinant receptors (GRs) was affected differently by NaCl, suggesting that GRs are targets of NaCl inhibition. However, NaCl also inhibited GR-independent germination, suggesting that there is at least one additional target for NaCl inhibition. Strikingly, a portion of the spore population could initiate germination with
l
-alanine even at NaCl concentrations near saturation (∼5.4 M), suggesting that spores lack a salt-sensing system preventing them from germinating in a hostile high-salinity environment. Spores that initiated germination at very high NaCl concentrations excreted their large depot of Ca
2+
-pyridine-2,6-dicarboxylic acid and lost their heat resistance, but they remained in a phase-gray state in the phase-contrast microscope, suggesting that there was incomplete germination. However, some metabolic activity could be detected at up to 4.8 M NaCl. Overall, high salinity seems to exert complex effects on spore germination and outgrowth whose detailed elucidation in future investigations could give valuable insights on these processes in general.
Mechanism for Stabilizing mRNAs Involved in Methanol-Dependent Methanogenesis of Cold-Adaptive Methanosarcina mazei zm-15
Authors: Cao Yi , Li Jie , Jiang Na , Dong Xiuzhu
Published: December 2013

Methylotrophic methanogenesis predominates at low temperatures in the cold Zoige wetland in Tibet. To elucidate the basis of cold-adapted methanogenesis in these habitats,
Methanosarcina mazei
zm-15 was isolated, and the molecular basis of its cold activity was studied. For this strain, aceticlastic methanogenesis was reduced 7.7-fold during growth at 15°C versus 30°C. Methanol-derived methanogenesis decreased only 3-fold under the same conditions, suggesting that it is more cold adaptive. Reverse transcription-quantitative PCR (RT-qPCR) detected <2-fold difference in the transcript abundances of
mtaA1
,
mtaB1
, and
mtaC1
, the methanol methyltransferase (Mta) genes, in 30°C versus 15°C culture, while
ackA
and
pta
mRNAs, encoding acetate kinase (Ack) and phosphotransacetylase (Pta) in aceticlastic methanogenesis, were 4.5- and 6.8-fold higher in 30°C culture than in 15°C culture. The
in vivo
half-lives of
mtaA1
and
mtaC1B1
mRNAs were similar in 30°C and 15°C cultures. However, the
pta-ackA
mRNA half-life was significantly reduced in 15°C culture compared to 30°C culture. Using circularized RNA RT-PCR, large 5′ untranslated regions (UTRs) (270 nucleotides [nt] and 238 nt) were identified for
mtaA1
and
mtaC1B1
mRNAs, while only a 27-nt 5′ UTR was present in the
pta-ackA
transcript. Removal of the 5′ UTRs significantly reduced the
in vitro
half-lives of
mtaA1
and
mtaC1B1
mRNAs. Remarkably, fusion of the
mtaA1
or
mtaC1B1
5′ UTRs to
pta-ackA
mRNA increased its
in vitro
half-life at both 30°C and 15°C. These results demonstrate that the large 5′ UTRs significantly enhance the stability of the mRNAs involved in methanol-derived methanogenesis in the cold-adaptive
M. mazei
zm-15.
Strain Design of Ashbya gossypii for Single-Cell Oil Production
Authors: Ledesma-Amaro Rodrigo , Santos María A. , Jiménez Alberto , Revuelta José Luis
Published: December 2013

Single-cell oil (SCO) represents a sustainable alternative for the oil industry. Accordingly, the identification of microorganisms with either higher lipidogenic ability or novel capacities for the transformation of raw materials constitutes a major challenge for the field of oil biotechnology. With this in mind, here, we were prompted to address the lipidogenic profile of the filamentous hemiascomycete
Ashbya gossypii
, which is currently used for the microbial production of vitamins. We found that
A. gossypii
mostly accumulates unsaturated fatty acids (FAs), with more than 50% of the total FA content corresponding to oleic acid. In addition, we engineered
A. gossypii
strains both lacking the beta-oxidation pathway and also providing ATP-citrate lyase (ACL) activity to block the degradation of FA and to increase the cytosolic acetyl-coenzyme A (CoA) content, respectively. The lipidogenic profile of the newly developed strains demonstrates that the mere elimination of the beta-oxidation pathway in
A. gossypii
triggers a significant increase in lipid accumulation that can reach 70% of cell dry weight. The use of
A. gossypii
as a novel and robust tool for the production of added-value oils is further discussed.
Ecology and Genetic Structure of Zoonotic Anisakis spp. from Adriatic Commercial Fish Species
Authors: Mladineo Ivona , Poljak Vedran
Published: December 2013

Consumption of raw or thermally inadequately treated fishery products represents a public health risk, with the possibility of propagation of liveAnisakislarvae, the causative agent of the zoonotic disease anisakidosis, or anisakiasis. We investigated the population dynamics ofAnisakisspp. in commercially important fish—anchovies (Anisakis), sardines (Sardina pilchardus), European hake (Merluccius merluccius), whiting (Merlangius merlangus), chub mackerel (Scomber japonicus), and Atlantic bluefin tuna (Thunnus thynnus)—captured in the main Adriatic Sea fishing ground. We observed a significant difference in the numbers of parasite larvae (1 to 32) in individual hosts and between species, with most fish showing high or very highAnisakispopulation indices. Phylogenetic analysis confirmed that commercial fish in the Adriatic Sea are parasitized byAnisakis pegreffii(95.95%) andAnisakis simplexsensu stricto(4.05%). The genetic structure ofA. pegreffiiin demersal, pelagic, and top predator hosts was unstructured, and the highest frequency of haplotype sharing (n= 10) was between demersal and pelagic fish.