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Angular and spectral separations of thermal radiation have become a key challenge in solar concentration or thermal management of sources radiating at extremely high or low temperatures. Reflections obtained from electromagnetic theory in an open cavity geometry increase the emission and absorption compared to a flat surface due to the cavity effect. In this paper, in order to obtain the directional emission of geometric surfaces (V-Grooves) using ray tracing and studying the propagation of light, a new algorithm is developed. The numerical simulations take into account the materials properties of both facets of the V-shape, thus simulating an original asymmetric and a multilayer V-shape and providing a very interesting directive thermal emission behavior. We evaluated the emission behavior from the reflection and emission coefficients of different rays at different angles for different parameters (materials properties, wavelength, and geometry). The simulations of a V-groove showed that due to the different reflections occurring inside an aluminum V-cavity with an aperture angle of 28°, the emissivity was well enhanced by 86% in the normal direction compared to a flat surface made of the same material. Moreover, using the original asymmetric opposite-sided materials (Al and Si) in a V- groove, it was possible to separate and control the emission by focusing the radiation or directing different spectral bands in different directions.

International audience

The use of phase change materials in buildings as a thermal energy storage system gained the attention of researchers all over the world. In the current study, coconut oil bio-based PCM is macro-encapsulated with enhanced thermal conductivity containers and coupled with hydronic radiant floor heating system. The study follows experimental aspect utilizing two identical small scale modular test prototypes. Investigations are directed toward studying the effect of the active CO-PCM system under different weather conditions, effect of combining active and passive systems, effect of PCM choice/type and effect of PCM location within the active floor, on the thermal and energy storage performances. Results revealed that coupling CO-PCM to active floor, passive wall and passive roof is capable of achieving load shifting and energy savings; and is affected by the control method, weather conditions, electricity tariff policy and PCM position and type. Further discussions, conclusions and perspective recommendations are summarized within the article.

International audience; Large computation time is widely considered to be the most important issue in scientific research especially in solving structural evolution problems. Recent developments in this domain have shown that the use of non-incremental schemes through Model Order Reduction led to important results in saving time. Yet, the question arises here how to obtain more time-saving. This paper examines an approach based on a collection of significant modes given by Proper Generalized Decomposition (PGD) solution for different time scales in order to save more computation time. The dictionary of the significant modes allows to construct an accurate solution for different characteristic times and different boundary problems compared to the full solution with a relative error rate less than 5% and with a large time saving of order 50 compared to Finite Element Method (FEM). The ability of the approach with respect to cycle time is discussed.

International audience; The effective piezoelectric properties of heterogeneous materials are evaluated in the context of periodic homogenization, whereby a variational formulation is developed, articulated with the extended Hill macrohomogeneity condition. The entire set of homogenized piezoelectric moduli is obtained as the volumetric averages of the microscopic properties of the individual constituents weighted by the displacement and polarization localization operators. This framework is extended in a second part of the paper to the computation of the flexoelectric effective properties, thereby accounting for higher gradient effects that may be induced by a strong contrast of properties of the composite constituents. The effective properties of inclusion-based composites are evaluated numerically as an illustration of the general homogenization theory and the respective effect of the volume fraction and relative tensile modulus of the reinforcement is assessed numerically.

International audience; The homogenization of viscoelastic composite materials gives rise to long-memory effects, reflected by the presence in the homogenized viscoelastic constitutive law of a delayed stress response expressed as a convolution integral involving the past material strain history. Computations reveal that the long-memory has the ability to delay or even absorb waves depending on the fraction of reinforcement and relative properties of the building phases with the composite. An approximation by a one-term Prony series of the computed spectrum of retardation times is shown to provide an accurate representation of the continuous spectrum of retardation times when simulating creep experiments. The long-memory effects entail shifts of the frequency band diagrams for both the natural and damped frequencies due to the presence of damping. Decreasing the effective retardation time of the composite leads to a faster attenuation of propagating longitudinal and shear waves.

International audience; Research interest to provide a mechanical solution for involuntary tremors is increasing due to the severe side effects caused by the medications used to lessen its symptoms. This paper deals with the design of a cantilever-type tuned mass damper (TMD) used to prove the effectiveness of passive controllers in reducing the involuntary tremor’s vibrational signals transmitted by the muscles to the hand segment. TMD is tested on an experimental arm, reflecting the flexion-extension motion of the wrist, excited by a mechanical shaker with the measured tremor signal of a patient with essential tremor. The designed TMD provides a new operational frequency for each position of the screw fixed to its beam. Modal damping ratios are also calculated using different methods for each position. The effectiveness of the TMD is quantified by measurements using a vibrometer and inertial measurement unit. Three TMDs, representing 15.7% total mass ratio, cause a reduction of 29% for the acceleration, 69% for the velocity, 79% for the displacement, 67% for the angular velocity, and 82% for the angular displacement signals. These encouraging results will allow the improvement of the design of the passive controller in the form of a wearable bracelet suitable for daily life

International audience; Phase Change Materials (PCM) have been a emerging research topic for the last few years. However, the lack of detailed and precise information regarding their thermophysical properties is a major concern for researchers. The current paper presents a simple method to determine the specific heat (Cp), thermal conductivity (K) and melting temperature (Tm) of a PCM using a novel low cost device. Compared to the conventional existing methods such as Differential Scanning Calorimetry (DSC), T-history, panel test and simple thermal analysis, this new method grants the following features: simplicity and ease of manufacturing and the ability to measure the thermophysical properties of heterogeneous PCMs samples without a reference material. Using this novel device, the thermophysical properties of the sodium sulfate decahydrate were measured and good agreement is obtained with values collected from the open literature using other devices.

Due to global warming and environmental issues in recent times, the world's concern is oriented nowadays toward discovering new renewable energy sources and energy management methods. Particularly, researchers are emphasizing on heat recovery technologies and applications in both residential and industrial sectors. While there are plenty of review papers in the literature on the subject matter, there is always a necessity to update the literature with the new advancements in the field. In this context, the purpose of this paper is to present a recent and complete systematic comprehensive review along with critical analysis and potential recommendations related to waste heat recovery (WHR) methodologies and applications. In methodologies, heat exchangers, Rankine cycle and thermoelectric generators are studied. Moreover, applications of WHR are discussed in automotive, and in both residential and industrial zones. Studies show that the optimization of heat recovery systems lead to significant magnitudes of energy savings. On the other hand, hybrid heat recovery systems prove to be the most trending research subject nowadays. For future work, the negative effect of backpressure should be taken into consideration when recovering energy from exhaust gases of engines and power generators, and more importance should be given to hybrid systems.

The non-volatile resistive state of memristor and the ease of controlling this state have triggered its usage in the design of non-volatile memories as well as logic design applications. The memristor based material implication (IMPLY) and memristor aided logic (MAGIC) have been recently presented as new methods to achieve logic computations inside memristive memory architectures. However, these methods are still surrounded by several design constraints. In this context, we present new design for memristive memories with an added computational capabilities. These capabilities are exclusively based on our proposed logic design style, namely Memristor Overwrite Logic (MOL) which is fully digital and tolerant against memristor technology variations.

Memristor technology has acquired great interest in the field of non-volatile memories as well as logic computation. The nano-scale structure of memristor and the possibility of its integration with MOSFETs have triggered many efforts to reconstruct basic digital building blocks. Recently, Memristor Ratioed Logic (MRL) has been introduced as a hybrid memristor-CMOS logic design style, which has been functionally validated. In this paper, a 1-bit full adder is designed by implementing MRL in crossbar array. The new design methodology efficiently integrates memristors at the top of CMOS layer. The corresponding layout and simulation results are performed using Cadence Virtuoso toolset targeting CMOS 65 nm process. The obtained results and their corresponding comparison illustrate promising outcomes in terms of implementation area, energy consumption and speed.

International audience; Sharing of renewable energy and reduction of conventional energy consumption as an attempt to ameliorate environmental issues such as global warming has become the main concern for current developing scientific engineering research. Moreover, with the drastic increase in cooling and heating requirements in the building sector worldwide, the need for suitable technology that enables improvement in thermal performance of buildings is addressed. Utilizing phase change materials (PCMs) for thermal energy storage strategies in buildings can meet the potential thermal comfort requirements when selected properly. The current research article presents an overview of different PCM cooling applications in buildings. The reviewed applications are classified into active and passive systems. A summary of the used PCMs and their respective properties are presented as well. Primary results of the studied systems are demonstrated to be efficient in reducing indoor temperature fluctuations and energy demand during cold seasons along with the capability of triggering load reduction or shifting. Highlights  A state-of-the-art review on cooling applications of PCM in buildings  Cooling PCM applications are classified as active and passive systems  PCM serves as a promising technology for energy-efficient buildings  Combining active and passive systems can be a potential step toward NZEB

The use of phase change material (PCM) as a thermal energy storage system integrated in new buildings, and as retrofits in old buildings, proved its merit as promising renewable energy source. Heating and cooling building applications of PCM have been studied by plenty of scientists, globally, on the basis of numerical and experimental analysis. The performed experiments have mainly focused on one application—active or passive—using permanent prototype design for a certain duration and weather condition. The current study is a new review that focuses on two complementary aspects: (1) Reviewing latest studies in PCM domain and assessing the thermal performance of implemented prototypes within the conducted PCM experimental studies, namely, the effect of the design on the number of acceptable variables and possible PCM applications; and (2) suggesting a new, advanced, flexible, and modular prototype designed to enable several applications of PCM to be adapted and combined within the model. It was implied that the new design allows different configurations that are lacking in the literature and serves for future PCM building applications of thermal analysis towards PCM integration optimization, as an attempt for transforming residential compartments into net zero energy buildings. The designed prototype overcomes the deficiencies found in previous reviewed experimental facilities.

International audience; Several methods are available to compute the anharmonicity in semirigid molecules. However, such methods are not yet routinely employed because of their high computational cost, especially for large molecules. The potential energy surface is required and generally approximated by a quartic force field potential based on ab initio calculation, thus limiting this approach to medium-sized molecules. We developed a new, fast, and accurate hybrid quantum mechanics/machine learning (QM/ML) approach to reduce the computational time for large systems. With this novel approach, we evaluated anharmonic frequencies of 37 molecules, thus covering a broad range of vibrational modes and chemical environments. The obtained fundamental frequencies reproduce results obtained using B2PLYP/def2tzvpp with a root-mean-square deviation (RMSD) of 21 cm–1 and experimental results with a RMSD of 23 cm–1. Along with this very good accuracy, the computational time with our hybrid QM/ML approach scales linearly with N, while the traditional full ab initio method scales as N2, where N is the number of atoms.

International audience

International audience; Wireless terabit-per-second (Tb/s) links will become an urgent requirement within the next 10 years. However, current methodology for high data rate wireless communication that keep increasing the M-ary modulation schemes and the order of MIMO spatial multiplexing cannot reach Tb/s with a low power consumption. Thus, a new methodology is required with a large bandwidth in the millimeter-wave (mm-Wave) and sub-Terahertz (sub-THz) bands above 90GHz. In addition, it must be able to provide an extremely high spectral efficiency with a low energy consumption. Note that this consumption can be reduced by using constant-envelope modulations such as continuous phase modulation (CPM). However, the CPM has a very low spectral efficiency that limits the desired data rate. This paper suggests a new methodology to reach 1 Tb/s with a low power consumption by using power efficient single carrier with Index Modulation (IM). Simulation results under various uncorrelated/correlated fading channels show that the systems with power efficient modulations as CPM or QPSK can achieve Tb/s with a good performance. Moreover, the link budget and power estimation prove that the constant and near-constant envelope modulations require less than 1−3 Watts for 1 Tb/s with 10 −4 un-coded BER. Finally, this paper shows that conveying most of the information bits using IM to reach an ultra-high data rate is more power efficient than high order MIMO spatial multiplexing with large M-ary QAM as used in LTE.

International audience; In the present study, coconut oil was used as a new bio-based phase change material (PCM) to be integrated with a quarter-scale insulated prototype of an underfloor heating system and its performance was investigated. Two different cases were studied. In the first case, the PCM was placed in an aluminum container that was positioned above an electrical heater, and the adaptation of the PCM to the floor was investigated. The second case was a control test in the absence of PCM plates. To simulate real severe winter conditions, the prototype was tested in an agricultural refrigerator to ensure constant low ambient temperature. The versatility of the underfloor system with PCM facilitates a reduction in heating load during winter while maintaining residential thermal comfort. An economic study was then conducted based on contemporary electricity shifts to inspect the system's ability in peak load shifting. The results show that the PCM achieved an increase of 53.7 % in the duration of energy transfer across charging and discharging. Furthermore, the use of the bio-PCM facilitated a shift in electricity consumption from peak time to off-peak time, yielding an annual cost reduction of 58.9% when compared with that achieved in the control test.

Area monitoring and surveillance are some of the main applications for Unmanned Aerial Vehicle (UAV) networks. The scientific problem that arises from this application concerns the way the area must be covered to fulfill the mission requirements. One of the main challenges is to determine the paths for the UAVs that optimize the usage of resources while minimizing the mission time. Different approaches rely on area partitioning strategies. Depending on the size and complexity of the area to monitor, it is possible to decompose it exactly or approximately. This paper proposes a partitioning method called Parallel Partitioning along a Side (PPS). In the proposed method, grid-mapping and grid-subdivision of the area, as well as area partitioning are performed to plan the UAVs path. An extra challenge, also tackled in this work, is the presence of non-flying zones (NFZs). These zones are areas that UAVs must not cover or pass over it. The proposal is extensively evaluated, in comparison with existing approaches, to show that it enables UAVs to plan paths with minimum energy consumption, number of turns and completion time while at the same time increases the quality of coverage.

International audience; Sharing of renewable energy and reduction of conventional energy consumption as attempts in ameliorating environmental issues such as global warming became the main concern for current developing scientific engineering research. And, with the remarkable increase in the cooling and heating demand in the building sector world widely, the need of a suitable technology that permits to the improvement of building thermal performance. Utilizing phase change materials (PCM) as thermal energy storage strategies in buildings can meet the potential thermal comfort requirements when selected properly. The current research article presents an overview of different PCM cooling applications in buildings. Active and passive classifications are presented. A summary of the used PCMs and their respective properties are also offered. Studied systems are proved to be efficient in reducing indoor temperature fluctuations and energy demand during cold seasons, with the capability of triggering load reduction or shifting.

In this work, numerical results focused on the enhancement of water-air heat exchanger thermal performance are presented. New designs consisting of using diffusers between the front end openings of the vehicle and the first exchanger facing the airflow are suggested. The diffuser will reduce the velocity magnitude but over a larger area through the exchanger. This will reduce the air velocity non-uniformity upstream the exchanger and then increase its thermal performance. An in-house code is established to evaluate the thermal performance of the exchanger based on known parameters; namely, the ratio of the area of the air inlet opening to the area of the exchanger, the distance between the air inlet opening and the first exchanger at its downstream, the angle of the diffuser, and the water and air mass flow rates. It was shown that the thermal performance of the exchanger can be enhanced by up to 67% when the diffuser is present depending on the configuration.

International audience; Adult T-cell leukemia/lymphoma (ATL) is an aggressive lymphoid proliferative disease that exists under diverse clinical forms ranging from chronic to acute. Although leukemic cells from patients with ATL exhibit an intrinsic resistance to chemotherapy, monoclonal antibodies directed against CD25 (interleukin 2 receptor ␣ [IL-2R␣] antibody) have been used as specific therapeutic agents. However, significant clinical results with these antibodies have been demonstrated only in chronic forms of ATL. In contrast to resting T cells, human T-cell lymphotropic virus type 1 (HTLV-1)-infected cells constitutively express high levels of surface transferrin receptor (TfR). Herein, we report the characterization of a new monoclonal antibody (mAb A24) directed against the human TfR and the evaluation of its capacity to block the proliferation of ATL cells ex vivo. We determined that A24 binds TfR with an equilibrium constant (K d) of 2.7 nM and competes with transferrin for binding to TfR. A24 also inhibited [ 55 Fe]-transferrin uptake in activated T cells and blocked T-cell proliferation. Moreover, A24 reduced and impaired TfR expression and recycling, respectively. Most important, we showed that A24 blocked the ex vivo proliferation of malignant T cells from both acute and chronic forms of ATL, through induction of programmed cell death. Therefore efficient therapeutic tools to treat acute forms of ATL might be derived from A24.