Hautes Études d'Ingénieur

The flywheel energy-storage systems (FESSs) are suitable for improving the quality of the electric power delivered by the wind generators and for helping these generators to contribute to the ancillary services. Supervisors must be used for controlling the power flow from a variable-speed wind generator (VSWG) to the power grid or to an isolated load. This paper investigates the control method and the energetic performances of a low-speed FESS with a classical squirrel-cage induction machine in the view of its association to a VSWG. A test bench is developed, and experimental results are presented and discussed

France has a high rate of road traffic crashes. 1 Although driver fatigue may be an important factor, 2-4 it has not been investigated in France, and no comparisons have been made with alcohol related crashes. We investigated the role of fatigue in serious road crashes using the French national database. 1

The local DC power distribution system of More Electric Aircraft is one of the cores of the electric power transmission. Because the mechanical source (turbine engine) is unidirectional, the system is not totally reversible. Some storage and dissipation systems are necessary to store or/and dissipate the returned energy to maintain the dc bus voltage. Different power-management strategies are proposed and compared. The development of experimental test benches is necessary to validate these strategies. In this paper, we present a 3-kW test bench, emulating a unidirectional source that supplies a bidirectional load with the help of a hybrid system using supercapacitors and a dissipation system. The experimental validation of the power-management strategies is presented in this paper, too.

The selection of measurements is one of the most important problems in the design of process instrumentation. This paper deals with the design of sensor networks such that the observability of the variables, which are necessary for the process control, remains satisfied in the presence of sensor failures. Pseudo-minimal and minimal sensor sets are organized into an oriented graph which contains all the possible reconfiguration paths for which those variables remain observable. A bottom-up analysis of this graph allows one to compute reliability functions which evaluate the robustness of the observability property with respect to sensor failures. The design of optimal sensor networks thus resumes to finding pseudo-minimal sensor sets such that the mean time before losing the observability property is larger than a pre-defined value.

Flywheel energy storage systems (FESSs) improve the quality of the electric power delivered by wind generators, and help these generators contributing to the ancillary services. Presently, FESSs containing a flux-oriented controlled induction machine (IM) are mainly considered for this kind of application. The paper proposes the direct torque control (DTC) for an IM-based FESS associated to a variable-speed wind generator, and proves through simulation and experimental results that it could be a better alternative. This DTC application entails two specific aspects: 1) the IM must operate in the flux-weakening region, and 2) it must shift quickly and repeatedly between motoring and generating operation modes. DTC improvement for increasing the FESS efficiency, when it operates at small power values, is discussed. Some aspects concerning the flywheel design and the choice of the filter used in the FESS supervisor are also addressed.

Reverberation chambers (RC), a name inspired in room acoustics, are also known in literature as reverberating, reverb, mode-stirred or mode-tuned chambers. In their basic form, they consist of a shielded metallic enclosure, forming a cavity resonator, together with some mode-stirring mechanism. The main goal of such stirring mechanism is to generate an amplitude-varying electromagnetic field that is ideally statistically uniform.

BACKGROUND AND AIMS: Mutant tumour derived DNA has been detected in the sera of colorectal cancer patients. We investigated if mutant serum KRAS2 was detectable preoperatively in a large group of patients with colorectal neoplasia. A prospective study of 94 patients who underwent putative curative resection for colorectal carcinoma (CRC) was performed to ascertain if serum mutant KRAS2 could be used postoperatively as a disease marker. METHODS: Preoperative sera from 78 patients were analysed (group A). Sera from 94 patients were obtained three monthly for up to three years during the postoperative period (group B). Codon 12 and 13 KRAS2 mutations were analysed in matched tumour and serum samples. RESULTS: In the preoperative group (group A), KRAS2 mutation was found in 41/78 (53%) tumours and in 32/78 (41%) preoperative sera. Of 41 tumour KRAS2 mutation positive cases, 31/41 (76%) had an identical serum mutation detectable. In group B, the postoperative follow up group, 60/94 cases were primary tumour KRAS2 mutation positive. Of these 60, 16/60 (27%) became persistently serum mutant KRAS2 positive postoperatively. Ten of 16 (63%) of these developed a recurrence compared with only 1/44 (2%) patients who remained serum mutant negative (odds ratio 71.7 (95% confidence interval 7.7-663.9; p=0.0000). None of 34 tumour mutation negative cases became serum mutant KRAS2 positive postoperatively, despite recurrence in 9/34 patients. The relative hazard of disease recurrence in postoperative serum mutant KRAS2 positive patients was 6.37 (2.26-18.0; p=0.000). CONCLUSIONS: Serum mutant KRAS2 can be detected preoperatively in all stages of colorectal neoplasia. Postoperatively, serum mutant KRAS2 is a strong predictor of disease recurrence, stronger even than Dukes' stage of disease, and thus shows potential for use in clinical practice as a marker of preclinical disease recurrence.

In this paper, a primary frequency control strategy based on fuzzy logic, designed for variable-speed wind generators, is proposed and tested on a 2.2 kW test bench. The fuzzy logic supervisor ensures a regular primary reserve for a large range of wind speeds without any wind speed measurement. This supervisor controls simultaneously the generator torque and the pitch angle to keep the primary reserve; it determines in real time the generator power reference value. The fuzzy logic supervisor is compared to a simpler strategy, based only on the control of the generator torque. This classical strategy ensures a regular power reserve only when the wind generator operates at full load, and the generator power reference needs to be determined previously or by the network manager. A procedure for implementing a fuzzy logic supervisor in real time is proposed. The experiments indicate the regularity of the power reserve and the ability to contribute to frequency control.

Abstract This paper addresses the problem of fault tolerant estimation and the design of fault tolerant sensor networks. Fault tolerance is defined with respect to a given estimation objective, namely a given functional of the system state should remain observable when sensor failures occur. Redundant and minimal sensor sets are defined and organized into an automaton which contains all the subsets of sensors such that the estimation objective can be achieved. Three criteria, which evaluate the system fault tolerance with respect to sensor failures when a reconfiguration strategy is used, are introduced: (strong and weak) redundancy degrees (RD), sensor network reliability (R), and mean time to non‐observability (MTTNO). Sensor networks are designed by finding redundant sensor sets whose RD and/or R and/or MTTNO are larger than some specified values. A ship boiler example is developed for illustration. Copyright © 2004 John Wiley & Sons, Ltd.

This paper seeks to assess the implications of the 1995 Judgement of the European Court of Justice on the case of Jean‐Marc Bosman for the operation of football transfer markets. Although it is inevitable that many more out‐of‐contract footballers will be able to move between dubs without payment of transfer fees to the selling club, it is argued that there remains a role for transfer markets in professional football, with compensation to selling clubs for training, development and replacement of players.

Abstract Only a subpopulation of non-small cell lung cancer (NSCLC) patients responds to immunotherapies, highlighting the urgent need to develop therapeutic strategies to improve patient outcome. We develop a chemical positive modulator (HEI3090) of the purinergic P2RX7 receptor that potentiates αPD-1 treatment to effectively control the growth of lung tumors in transplantable and oncogene-induced mouse models and triggers long lasting antitumor immune responses. Mechanistically, the molecule stimulates dendritic P2RX7-expressing cells to generate IL-18 which leads to the production of IFN-γ by Natural Killer and CD4 + T cells within tumors. Combined with immune checkpoint inhibitor, the molecule induces a complete tumor regression in 80% of LLC tumor-bearing mice. Cured mice are also protected against tumor re-challenge due to a CD8-dependent protective response. Hence, combination treatment of small-molecule P2RX7 activator followed by immune checkpoint inhibitor represents a strategy that may be active against NSCLC.

This chapter contains sections titled: Introduction Geothermal power Thermodynamic solar power generation Cogeneration by biomass Bibliography

Fouling is a widespread and costly issue, faced by all food-processing industries. Particularly, in the dairy sector, where thermal treatments are mandatory to ensure product safety, heat-induced fouling represents up to 80% of the total production costs. Significant environmental impacts, due the massive consumption of water and energy, are also to deplore. Fouling control solutions are thus desperately needed, as they would lead to substantial financial gains as well as tremendous progress toward eco-responsible processes. This work aims at presenting a novel and very promising dairy fouling-mitigation strategy, inspired by nature, and to test its antifouling performances in real industrial conditions. Slippery liquid-infused surfaces were successfully designed directly on food grade stainless steel, via femtosecond laser ablation, followed by fluorosilanization and impregnation with an inert perfluorinated oil. Resulting hydrophobic surfaces (water contact angle of 112°) exhibited an extremely slippery nature (contact angle hysteresis of 0.6°). Outstanding fouling-release performances were obtained for these liquid-infused surfaces as absolutely no trace of dairy deposit was found after 90 min of pasteurization test in pilot-scale equipment followed by a short water rinse.

This paper details the digital implementation of a new observation strategy of the flying capacitor voltages dedicated to stacked multicell converters (SMC). This particular topology relies on the use of flying capacitors so as to equally share the voltage constraint on several semiconductors and increase the number of output levels. However, the SMC appropriate operation is guaranteed by the stability of the flying capacitor voltage levels, and the current flow creates variations of those quantities. The idea is therefore to develop an accurate estimation technique that avoids the utilization of differential sensors and allows the active control of the intermediate voltages. The observation has to meet several criteria. It must particularly reproduce in a quasi-analog way the dynamic of those quantities to enable the proper operation of the active control algorithm. The actual research scope thus focuses on the sliding mode observation of the flying capacitor voltages by means of phase current measurements. This paper summarizes the observer design, its digitizing, and the field-programmable gate array (FPGA) implementation. It also presents an interesting Very High Speed Integrated Circuit Hardware Description Language (VHDL)-Saber Cosimulation tool that allows validating the VHDL code before being downloaded in the FPGA of the physical system. The last section illustrates and emphasizes the performance and ruggedness of the implemented algorithm through promising experimental results.

Abstract Because of their dismutation into benzophenones and diphenylmethanes, it is necessary to use chlorotrimethylsilane and not triflic acid as a catalyst for the silylation of diarylcarbinol with hexamethyl-disilazane.

The molecular structure of fullerene ${\mathrm{C}}_{60}$ has been determined with high precision using neutron scattering over a large range of momentum-transfer values. In the high-temperature plastic phase, at 295 K, the description of the complete structure factor in the 0--20-A${\mathrm{\r{}}}^{\mathrm{\ensuremath{-}}1}$ range, including Bragg and diffuse intensities, confirms the free reorientation of the ${\mathrm{C}}_{60}$ spherical molecules. This analysis gives the carbon-carbon bond length within the five-member ring (single bond) equal to 1.4527(7) \AA{}, and that connecting five-member rings (double bond) equal to 1.3909(10) \AA{}. As the temperature is lowered to 4 K, the structural parameters are extracted from the analysis of the intramolecular contributions to the diffuse intensity in the 6.5--20-A${\mathrm{\r{}}}^{\mathrm{\ensuremath{-}}1}$ range: the single bond is elongated [1.460(2) \AA{}] and the double bond shortened [1.381(3) \AA{}], indicating that electrons get more localized on the \ensuremath{\pi} orbitals. The calculation method allows us to consider small distortions from the ideal truncated icosahedral model (oblate or prolate deformations); the method could easily be extended to the study of substituted fullerene molecules.

Triplet decay of Mg and Zn phthalocyanins have been studied by laser flash photolysis as a function of concentration. The triplet decay mechanism changes from a near first order in dilute solution to an almost second order in concentrated solutions. This is interpreted in terms of triplet–triplet recombinaison. With the help of a reducing agent, it is shown that the triplet–triplet reaction can lead to charge separation. La décroissance des états excités triplet des phthalocyanines de Mg et de Zn a été étudiée par photolyse éclair laser en fonction de la concentration. Le mécanisme de décroissance du triplet passe d′un premier ordre presque idéal en solution diluée à un quasi second ordre en solution concentrée. Ceci s′explique par une recombinaison triplet–triplet. A l′aide d′un réducteur, la réaction triplet–triplet peut conduire à une séparation de charges.

(1955). Experiments on the range of validity of Darcy's law and the appearance of turbulence in a filtering flow. La Houille Blanche: Vol. 41, No. 2, pp. 141-149.

Elderly populations in Asian countries are expected to increase rapidly in the next few decades. Older adults, particularly in high-density cities, spend a considerable amount of time in urban green spaces (UGSs). The World Health Organization noted that UGSs are key to improving the age-friendliness of neighborhoods. Thus, it is necessary to design UGSs for the promotion of healthy ageing to enhance preventive healthcare and relieve medical burdens. This study conducted interviews using a questionnaire with a sample size of 326 participants in the cities of Hong Kong (China) and Tainan (Taiwan region). The inter-relationships among the design of UGSs (e.g., spatial distribution and accessibility, characteristics of plants and UGSs), older adults' perceptions on safety and aesthetics quality of UGSs, and their self-reported health conditions (assessed by the self-reported SF-12v2 Health Survey) were investigated with bivariate Spearman rank correlation tests. The results indicate that the duration of visits to UGSs was positively associated with mental health and social functioning, two subscales evaluating health-related quality of life in SF 12v2. The statistical model (moderation analysis) showed that such a correlation was especially significant in women and those with low social support and social capital. A positive relationship was found between the physical health subscale and perceived safety in UGSs. This relationship was stronger among older adults living alone (moderation analysis). Furthermore, the color of plants and maintenance condition of UGSs were significant aspects affecting the subjective assessment of aesthetic quality. This study provides useful information regarding how to plan and design urban green spaces with certain characteristics that could improve the accessibility and aesthetic quality, which are preferred by older adults.

In this paper, the hole drilling (HD) and the cold expansion (CE) processes, which were used as a technique for crack repair, were investigated in order to estimate the beneficial effects on fatigue crack initiation (FCI). The FCI life is defined as the number of cycles to initiate a new crack of 0.2 mm on the surface of the specimen. Three hole radii and three degrees of cold expansion ( DCE %) values were tested after a crack propagation period. Crack retardation after the CE process was observed. This phenomenon is due to two mechanisms: retardation owing to both geometric and mechanical effects, which is produced by the stress concentration at the drilled hole, and the large strain‐induced compressive residual stresses around the hole. In this report, the influence of the loading conditions was studied. For high values of the stress intensity factor range Δ K ρ around the hole (based on the pseudo crack length a + ρ), the number of cycles corresponding to crack initiation N i is low. At the edge of the hole, the maximum stress range can be approximated by the following formula: Δ σ max = 2Δ K ρ /√ πρ , where ρ is the hole radius and Δ K ρ is the related stress intensity factor range.The FCI life extension, defined by the number of cycles corresponding to crack re‐initiation N i , is related to the relative maximum stress range ratio R σ = [(Δ σ max )/(Δ σ max ) th ] where (Δ σ max ) th is the value of the threshold maximum stress range obtained when N i = 2 × 10 6 cycles. The relationship between N i and R σ may be written as a power function.