The purpose of this work is the optimal conception of a wing built using fused deposition modeling (FDM), which is one of the main additive manufacturing (AM) process.PLA reinforced with carbon fiber was selected for the filament as we have defined their mechanical properties in previous work.The optimization approach use hybrid strategy based on surface response method with kriging model and a heuristic method to avoid to be trapped in local minimization/maximization.The objective functions for this optimization are the weight, the drag (functions to minimize) and the lift (function to maximize) with respect to the failure criteria of the composite material used to build the fuselage.The challenge for this kind of optimization is the multilevel aspect, as it requires firstly to get the optimal parameters of the model before getting the optimal distribution of thicknesses.
The NUMEN project aims at accessing experimentally driven information on Nuclear Matrix Elements (NME) involved in the half-life of the neutrinoless double beta decay (0v beta beta), by high-accuracy measurements of Heavy Ion (HI) induced Double Charge Exchange (DCE) reaction cross sections. In particular, the (O-18,Ne-18) and (Ne-20, O-20) reactions are used as tools for beta(+)beta(+) and beta(-)beta(-) decays, respectively. In the experiments, performed at INFN - Laboratory Nazionali del Sud (LNS) in Catania, the beams are accelerated by the Superconducting Cyclotron (CS) and the reaction ejectiles are detected the MAGNEX magnetic spectrometer. The measured cross sections are challengingly low (a few nb), being the total reaction cross section much larger (a few b), thus a high sensitivity and a large rejection capability are demanded to the experimental set-up. This limits the present exploration to few selected isotopes of interest in the context of typically low-yield experimental runs. A major upgrade of the LNS facility is foreseen in order to increase the experimental yield of at least two orders of magnitude, still keeping the high sensitivity of the present set-up, making it feasible a systematic study of all the cases of interest. Frontiers technologies are going to be developed, to this purpose, for the accelerator and the detection systems. In parallel, advanced theoretical models are being developed in order to extract the nuclear structure information from the measured cross sections.
Bio materials have seen an increase of interest from the scientific community and the industry as a possible future generation of mass produced materials, some of the main arguments being their renewability, low production costs and recyclability.The current work is focused on the experimental data required for the viscoelastic characterization of a composite material. Similar work has been conducted on different types of composite materials by Tuttle and Brinson [1] who verified for a carbon epoxy laminate the possibility of long term predicament of creep. Nordin et al [2] studied paper impregnated with phenol-formaldehyde under compression. Muliana [3] conducted experiments on E-glass/vinyl ester materials. Behavior characterization was based on a model presented by Schapery [4]. The main objective of this work is to understand the mechanical behaviors of bio-laminates structures subjected to long and severe operating conditions.The studied material is a bio composite laminate consisting in long flax fibers embedded in an epoxy resin system. The laminates were obtained from pre-impregnated unidirectional fibers, which were cured though a thermo-compression cycle followed by a post curing cycle. Test specimens were cut down to sizes, with the help of an electric saw. The concerned fiber direction was 0° with sample dimensions of 250x25x2 mm.First, testing consisted in quasi static mechanical tests. Second, to characterize linear viscoelastic behavior of the bio-laminates, creep – recovery tests with multiple load levels have been performed for the chosen fiber direction.
Several procedures in medicine (such as anesthesia, injections, biopsies and percutaneous treatments) involve a needle insertion. Such procedures operate without vision of the internal involved areas. Physicians and anesthetists rely on manual (force and tactile) feedback to guide their movements, so a number of medical practice is strongly based on manual skill. In order to be expert in the execution of such procedures the medical students must practice a number of times, but before practice in a real patient they must be trained in some place and a virtual environment, using Virtual Reality (VR) or Augmented Reality (AR) is the best possible solution for such training. In a virtual environment the success of user practices is improved by the addition of force output using haptic device to improve the manual sensations in the interactions between user and computer. Haptic devices enable simulate the physical restriction of the diverse tissues and force reactions to movements of operator hands. The trainees can effectively "feel" the reactions to theirs movements and receive immediate feedback from the actions executed by them in the implemented environment. However, in order to implement such systems, the tissue reaction to penetration and cutting must be modeled. A proper model must emulate the physical sensations of the needle action in the skin, fat, muscle, and so one, as if it really done in a patient that is as they are holding a real needle and feeling each tissue resistance when inserting it through the body. For example an average force value for human skin puncture is 6.0 N, it is 2.0 N for subcutaneous fat tissue and 4.4 N for muscles: this difference of sensations to penetration of each layers trespassed by the needle makes possible to suppose the correct position inside the body. This work presents a model for tissues before and after the cutting that with proper assumptions of proprieties can model any part of human body. It was based on experiments and used in embryonic system for epidural anesthesia having good evaluation as presented in the last section "Preliminary Results".
In this paper, we introduce a new accumulation process, the Semi-Markov Accumulation Process (SMAP). This class of processes extends the framework of continuous-time Markov Additive Processes (MAPs) by allowing the underlying environmental component to be a semi-Markov process instead of a Markov process. Next, we follow an analytic approach to derive a Master Equation formula of the Renewal type that describes the evolution of SMAPs in time. We show that under exponential holding times, a matrix exponential form analogous to the matrix exponent of a MAP is attained. Finally, we consider an application of our results where closed-form solutions are rather easy to achieve.
The main parameters of InGaP and GaAs thin solar cells (SCs) at average light concentration ratios (X) of ~54 and ~93 suns were investigated in the temperature range 25-250 °C. The main parameters of the two devices showed quasi-linear behaviors with increasing the operating temperature. The conversion efficiencies were found to drop ~27 and ~40 % in InGaP and GaAs, respectively independently of the two concentration ratios. Furthermore, the two devices showed a decrease in output power averagely ranging from 25 to 27 %, which yields to a difference less than 2%. In term of thermal reliability, the two devices did not show significant degradation after approximately 4 months of heat dumping. Hence, these results imply that GaAs still deliver more output power at 250 °C.
Numerical methods for solving convection-diffusion-reaction (CDR) scalar transport equation in three-dimensional flow are used in the present investigation. The flow is confined between two concentric cylinders both the inner cylinder and the outer one are allowed to rotate. Direct numerical simulations (DNS) have been achieved to study the effects of the gravitational and the centrifugal potentials on the stability of incompressible Taylor-Couette flow. The Navier-Stokes equations and the uncoupled convection–diffusion–reaction equation are solved using a spectral development in one direction combined together with a finite element discretization in the two remaining directions. The complexity of the patterns is highlighted. Since, it increases as the rotation rates of the cylinders increase. In addition, the effect of the counter-rotation of the cylinders on the mass transfer is pointed out.
The central focus of the research is on conducting a societal metabolism approach to the region of Pays de la Loire in France. For doing so, the Multi-Scale Integrated Analysis of Societal and Ecosystem Metabolism (MuSIASEM) methodology is used where fund variables such as human activity and land use are correlated over flow variables, such as energy and gross added value following the theoretical framework of Georgescu-Roegen [1]. Thereafter the feasibility, viability and desirability of current development patterns for the region are questioned to be able to transition into alternative scenarios.
Mucus is mainly composed of water (90-95%) and mucins (2-5%), these mucins being high molecular weight macromolecules forming a 3D cross-linked matrix. It makes it a complex non-Newtonian fluid, displaying viscoplasticity, viscoelasticity, shear-thinning and thixotropy. These properties were qualitatively and separately tested by different authors. Due to the difficulties to collect samples and the extreme sensibility of the tested materials, the results are widely variable. A complete and intrinsically consistent characterization remains to be done to develop a reliable rheological model for future numerical simulations of mucus displacements in airways, in the case of pathologies such as cystic fibrosis. For this purpose, samples of mucus simulants were tested using a controlled stress rheometer. The material consists of macromolecular colloidal gels at different concentrations in macromolecules to mimic the variability in mucin production depending on the disease state and environmental factors. The rheological properties at rest were investigated using small amplitude oscillatory shear tests as a function of stress amplitude, frequency and temperature. They revealed that mucus simulant behaves as a gel within a defined linear viscoelastic region and as a viscoelastic liquid above the yield stress zone. To characterize the behavior of mucus in response to in vivo shearing induced by cough or by air flows produced by clearance helping devices, steady state flow tests have been performed. The steady state flow curves for various polymer concentrations are well fitted using a Herschel-Bulkley law. To account for the time dependent behavior of mucus, 3 intervals thixotropy tests were also implemented to monitor structure breakdown and buildup processes. The combination of all these measurements finally designs a reliable procedure accounting for the rheological complexities of mucus, that now needs to be applied to real mucus for validations.
This paper presents a numerical study of the shock-bubble interaction of a compressible two-phase flows. The investigations such flows are performed using an inviscid one-fluid solver in the presence of shock wave and strong rarefaction waves similar to cavitation. The code is composed by three conservation laws for mixture variables, namely mass, momentum and total energy along with supplementary transport equation for the volume fraction of the gas phase. Simulation results are carried out on a shock-bubble interaction case leading to the cavity collapse. The results of the numerical simulation exhibit a good agreement with numerical results presented by other researchers.
We demonstrate the feasibility approach to deploy two types of dual junction GaInP/Ge and GaAs/Ge solar cells in a hybrid photovoltaic-solar thermal concentrator system, where they can operate at 250 degrees C and at medium light concentration. These devices were designed to transfer absorbed heat to tube with a fluid, using high thermal conductivity of Ge substrate. Both heterostructures showed no significant degradation after a high temperature thermal storage of over 7 months long. Regarding their performance, the GaAs/Ge dual junction showed similar to 1% higher absolute efficiency than the InGaP/Ge, at 250 degrees C and 170 suns.
Ultrasonic field simulation is a key ingredient for the design of new testing methods as well as a crucial step for NDT inspection simulation. As presented in a previous paper [1], CEA-LIST has worked on the acceleration of these simulations focusing on simple geometries (planar interfaces, isotropic materials). In this context, significant accelerations were achieved on multicore processors and GPUs (Graphics Processing Units), bringing the execution time of realistic computations in the 0.1 s range.In this paper, we present recent works that aim at similar performances on a wider range of configurations. We adapted the physical model used by the CIVA platform to design and implement a new algorithm providing a fast ultrasonic field simulation that yields nearly interactive results for complex cases. The improvements over the CIVA pencil-tracing method include adaptive strategies for pencil subdivisions to achieve a good refinement of the sensor geometry while keeping a reasonable number of ray-tracing operations. Also, interpolation of the times of flight was used to avoid time consuming computations in the impulse response reconstruction stage.To achieve the best performance, our algorithm runs on multi-core superscalar CPUs and uses high performance specialized libraries such as Intel Embree for ray-tracing, Intel MKL for signal processing and Intel TBB for parallelization. We validated the simulation results by comparing them to the ones produced by CIVA on identical test configurations including mono-element and multiple-element transducers, homogeneous, meshed 3D CAD specimens, isotropic and anisotropic materials and wave paths that can involve several interactions with interfaces. We show performance results on complete simulations that achieve computation times in the 1s range.
The protein p53 as a tumour suppressor protein accumulates in cells in response to DNA damage and transactivates a large variety of genes involved in apoptosis, cell cycle regulation and numerous other processes. Recent biological observations suggest that specific spatio-temporal dynamical patterns of p53 may be associated with specific cellular response, and thus the spatio-temporal heterogeneity of the p53 dynamics contributes to the overall complexity of p53 signalling. Reaction-diffusion equations taking into account spatial representation of the cell and motion of the species inside the cell can be used to model p53 protein network and could be thus of some help to biologists and pharmacologists in anticancer treatment.
In this study, a model of transport phenomena describes a single bubble growth in semi-hard cheese. Carbon dioxide production, its transport to the bubble interface, equilibrium laws and mechanics were coupled. Semi-hard cheese mainly behaves as elastic when loads are quickly applied to a piece of cheese like during chewing (few seconds). However, when slowly loaded with increasing gas pressure during ripening in warm room, the mechanical cheese behavior can be simply modelled as a viscous material (Grenier et al. [9]). It is true, as long as viscosity remains low compared to the rate of gas production. This paper investigates a wider range of viscosity (from core η = 6.32 × 107 Pa.s to rind η = 2.88 × 108 Pa.s) than that used in previous studies. FEM simulations have shown that higher viscosities encountered close to the rind of a cheese block can partly explain the increase in gas pressure within bubbles from the core to the rind (up to 3.4 kPa). These results confirm that mechanics does not really control the evolution of bubble volume in cheese. However, mechanics can explain greater pressure observed close to the rind even if gas production is lower than at core.
In this contribution, we investigate the small-signal admittance of the high electron mobility transistors field-effect channels under a continuation branching of the current between channel and gate by using an analytical model. The analytical approach takes into account the linearization of the 2D Poisson equation and the drift current along the channel. The analytical equations discuss the frequency dependence of the admittance at source and drain terminals on the geometrical transistor parameters.
An ultrasonic nondestructive methodology is proposed for the assessment of low velocity impact damage in a 3D woven composite material. The output data is intended for material scientists and numerical scientists to validate the damage tolerance performance of the manufactured materials and the reliability of damage modeling predictions. A depthdependent threshold based on the reflectivity of flat bottom holes is applied to the ultrasonic data to remove the structural noise and isolate echoes of interest. The methodology was applied to a 3 mm thick 3D woven composite plate impacted with different energies. An artificial 3D representation of the detected echoes is proposed to enhance the spatial perception of the generated damage by the end user. The paper finally highlights some statistics made on the detected echoes to quantitatively assess the impact damage resistance of the tested specimens.
We estimate the density of a set of biophysical parameters from region censored observations. We propose a new Maximum Entropy (maxent) estimator formulated as finding the most likely constrained maxent density. By using the Ŕnyi entropy of order two instead of the Shannon entropy, we are lead to a quadratic optimization problem with linear inequality constraints that has an efficient numerical solution. We compare the proposed estimator to the NPMLE and to the best fitting maxent solutions in real data from hyperbaric diving, showing that the resulting distribution has better generalization performance than NPMLE or maxent alone.
We show that the maximum transmission distance of continuous-variable quantum key distribution in presence of a Gaussian noisy lossy channel can be arbitrarily increased using a heralded noiseless linear amplifier. We explicitly consider a protocol using amplitude and phase modulated coherent states with reverse reconciliation. Assuming that the secret key rate drops to zero for a line transmittance Tlim, we find that a noiseless amplifier with amplitude gain g can improve this value to Tlim/g2, corresponding to an increase in distance proportional to log g. We also show that the tolerance against noise is increased.
The impact of aerosol on clouds and precipitation varies depending on the cloud type. This case study focusses on convective clouds developing after the passage of a frontal system from the North Sea over Germany. In contrast to deep convection, the precipitation amount formed in the postfrontal cummuli is thought to show a systematic sensitivity to the natural and anthropogenic aerosol burden. During the front passage, the preexisting anthropogenic aerosol is replaced to a large extent by seasalt aerosol. To quantify the influence of aerosol on these postfrontal cummuli and their precipitation simulations with a comprehensive online coupled model system are performed. As precipitation reacts sensitive to disturbances of any atmospheric state variable, also simulations with slightly and randomly disturbed temperature fields were performed to contrast these effects with the aerosol effect.
