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Combining thermal scanning probe lithography and dry etching for grayscale nanopattern amplification

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Microsystems & Nanoengineering 2024年第1期10卷 335-344页

作者： Berke Erbas Ana Conde-Rubio Xia Liu Joffrey Pernollet Zhenyu Wang Arnaud Bertsch Marcos Penedo Georg Fantner Mitali Banerjee Andras Kis Giovanni Boero Juergen Brugger Microsystems Laboratory École Polytechnique Fédérale de Lausanne(EPFL)Lausanne 1015Switzerland Center of MicroNanoTechnology(CMi) EPFLLausanne 1015Switzerland Laboratory of Nanoscale Electronics and Structures École Polytechnique Fédérale de Lausanne(EPFL)Lausanne 1015Switzerland Laboratory for Bio-and Nano-Instrumentation École Polytechnique Fédérale de Lausanne(EPFL)Lausanne 1015Switzerland Laboratory of Quantum Physics Topology and CorrelationsÉcole Polytechnique Fédérale de Lausanne(EPFL)Lausanne 1015Switzerland Present address:Institute of Materials Science of Barcelona ICMAB-CSIC Campus UABBellaterra 08193Spain Present address:School of Integrated Circuits and Electronics MIIT Key Laboratory for Low-Dimensional Quantum Structure and DevicesBeijing Institute of TechnologyBeijing 100081China

Grayscale structured surfaces with nanometer-scale features are used in a growing number of applications in optics and *** scanning probe lithography achieves a lateral resolution below 10 nm and a vertical resolution below 1 nm,but its maximum depth in polymers is ***,we present an innovative combination of nanowriting in thermal resist and plasma dry etching with substrate cooling,which achieves up to 10-fold amplification of polymer nanopatterns into SiO_(2) without proportionally increasing surface *** nanopatterns in SiO_(2) with 400 nm pitch and 150 nm depth are fabricated free of shape distortion after dry *** exemplify the possible applications of the proposed method,grayscale dielectric nanostructures are used for scalable manufacturing through nanoimprint lithography and for strain nanoengineering of 2D *** a method for aspect ratio amplification and smooth grayscale nanopatterning has the potential to find application in the fabrication of photonic and nanoelectronic devices.

关键词： lithography thermal pattern

结合偏振复用和铁磁非互易技术实现带内全双工无线通信系统超高隔离（英文）

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Engineering 2024年第9期 179-187页

作者： Amir Afshani Ke Wu Poly-Grames Research Center Department of Electrical Engineering école Polytechnique de Montréal

The in-band full-duplex(IBFD) wireless system is a promising candidate for 6G and beyond, as it can double data throughput and enormously lower transmission latency by supporting simultaneous in-band transmission and reception of signals. Enabling IBFD systems requires a substantial mitigation of a transmitter(Tx)'s strong self-interference(SI) signal into the receiver(Rx) channel. However, current state-ofthe-art approaches to tackle this challenge are inefficient in terms of performance, cost, and complexity,hindering the commercialization of IBFD techniques. In this work, we devise and demonstrate an innovative approach to realize IBFD systems that exhibit superior performance with a low-cost and lesscomplex architecture in an all-passive module. Our scheme is based on meticulously combining polarization-division multiplexing(PDM) with ferromagnetic nonreciprocity to achieve ultra-high isolation between Tx and Rx channels. Such an unprecedented conception has become feasible thanks to a concurrent dual-mode circulator-a new component introduced for the first time-as a key feature of our module, and a dual-mode waveguide that transforms two orthogonally polarized waves into two orthogonal waveguide modes. In addition, we propose a unique passive tunable secondary SI cancellation(SIC) mechanism, which is embedded within the proposed module and boosts the isolation over a relatively broad bandwidth. We report, solely in the analog domain, experimental isolation levels of 50, 70,and 80 d B over 340, 101, and 33 MHz bandwidth at the center frequency of interest, respectively, with excellent tuning capability. Furthermore, the module is tested in two real IBFD scenarios to assess its performance in connection with Tx-to-Rx leakage and modulation error in the presence of a Tx's strong interference signal.

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Improving the operational stability of perovskite solar cells with cesium-doped graphene oxide interlayer

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Journal of Energy Chemistry 2024年第9期96卷 483-490页

作者： Masaud almalki Katerina Anagnostou Konstantinos Rogdakis Felix T.Eickemeyer Mostafa Othman Minas M.Stylianakis Dimitris Tsikritzis Anwar Q.alanazi Nikolaos Tzoganakis Lukas Pfeifer Rita Therisod Xiaoliang Mo Christian M.Wolff Aïcha Hessler-Wyser Shaik M.Zakeeruddin Hong Zhang Emmanuel Kymakis Michael Grätzel Laboratory of Photonics and Interfaces École Polytechnique Fédérale de Lausanne(EPFL)Lausanne 1015Switzerland department of Electrical and Computer Engineering Hellenic Mediterranean UniversityHeraklionCrete 71410Greece Institute of Electrical and Microengineering(IEM)Photovoltaics and Thin-Film Electronics Laboratory(PV-Lab) École Polytechnique Fédérale de Lausanne(EPFL)Neuchâtel 2000Switzerland department of Nursing Faculty of Health SciencesHellenic Mediterranean UniversityCrete 71410Greece Centre Interdisciplinaire de Microscopie Electronique École Polytechnique Fédérale de Lausanne(EPFL)Lausanne 1015Switzerland Future Energy Technology Institute King Abdulaziz City for Science and Technology(KACST)P.O.Box 6086Riyadh 11442Saudi Arabia State Key Laboratory of Photovoltaic Science and Technology Shanghai Frontiers Science Research Base of Intelligent Optoelectronics and PerceptionInstitute of OptoelectronicsDepartment of Materials ScienceFudan UniversityShanghai 200433China

Perovskite solar cells(PSCs)have made great advances in terms of power conversion efficiency(PCE),yet their subpar stability continues to hinder their *** interface between the perovskite layer and the charge-carrier transporting layers plays a crucial role in undermining the stability of *** this work,we propose a strategy to stabilize high-performance PSCs with PCE over 23%by introducing a cesium-doped graphene oxide(GO-Cs)as an interlayer between the perovskite and hole-transporting *** GO-Cs treated PSCs exhibit excellent operational stability with a projected T80(the time where the device PCE reduces to 80%of its initial value)of 2143 h of operation at the maximum powering point under one sun illumination.

关键词： Perovskite solar cells Doped graphene oxide Graphene related material Long-term operational stability

Programming nonlinear propagation for efficient optical learning machines

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Advanced Photonics 2024年第1期6卷 73-83页

作者： Ilker Oguz Jih-Liang Hsieh Niyazi Ulas Dinc Ugur Tegin Mustafa Yildirim Carlo Gigli Christophe Moser demetri Psaltis École polytechnique Fédérale de Lausanne Institute of Electrical and Micro EngineeringEcublensSwitzerland Koc University Department of Electrical and Electronics EngineeringIstanbulTurkey

The ever-increasing demand for training and inferring with larger machine-learning models requires more efficient hardware solutions due to limitations such as power dissipation and *** is a promising contender for providing lower power computation,since light propagation through a nonabsorbing medium is a lossless ***,to carry out useful and efficient computations with light,generating and controlling nonlinearity optically is a necessity that is still *** fibers(MMFs)have been shown that they can provide nonlinear effects with microwatts of average power while maintaining parallelism and low *** propose an optical neural network architecture that performs nonlinear optical computation by controlling the propagation of ultrashort pulses in MMF by wavefront *** a surrogate model,optimal sets of parameters are found to program this optical computer for different tasks with minimal utilization of an electronic *** show a remarkable decrease of 97%in the number of model parameters,which leads to an overall 99%digital operation reduction compared to an equivalently performing digital neural *** further demonstrate that a fully optical implementation can also be performed with competitive accuracies.

关键词： neural networks nonlinear optics fiber optics surrogate optimization neuromorphic computing wavefront shaping

Improving the utility of locally differentially private protocols for longitudinal and multidimensional frequency estimates

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Digital Communications and Networks 2024年第2期10卷 369-379页

作者： Héber H.Arcolezi Jean-François Couchot Bechara al Bouna Xiaokui Xiao Inria andÉcole polytechnique(IPP) PalaiseauFrance Femto-ST Institute Univ.Bourg.Franche-ComtéUBFCCNRSBelfortFrance TICKET Lab. Antonine University Hadat-BaabdaBaabdaLebanon School of Computing National University of SingaporeSingaporeSingapore

This paper investigates the problem of collecting multidimensional data throughout time(i.e.,longitudinal studies)for the fundamental task of frequency estimation under Local Differential Privacy(LDP)*** to frequency estimation of a single attribute,the multidimensional aspect demands particular attention to the privacy ***,when collecting user statistics longitudinally,privacy progressively ***,the“multiple”settings in combination(i.e.,many attributes and several collections throughout time)impose several challenges,for which this paper proposes the first solution for frequency estimates under *** tackle these issues,we extend the analysis of three state-of-the-art LDP protocols(Generalized Randomized Response–GRR,Optimized Unary Encoding–OUE,and Symmetric Unary Encoding–SUE)for both longitudinal and multidimensional data *** the known literature uses OUE and SUE for two rounds of sanitization(***),i.e.,L-OUE and L-SUE,respectively,we analytically and experimentally show that starting with OUE and then with SUE provides higher data utility(i.e.,L-OSUE).also,for attributes with small domain sizes,we propose Longitudinal GRR(L-GRR),which provides higher utility than the other protocols based on unary ***,we also propose a new solution named Adaptive LDP for LOngitudinal and Multidimensional FREquency Estimates(alLOMFREE),which randomly samples a single attribute to be sent with the whole privacy budget and adaptively selects the optimal protocol,i.e.,either L-GRR or *** shown in the results,alLOMFREE consistently and considerably outperforms the state-of-the-art L-SUE and L-OUE protocols in the quality of the frequency estimates.

关键词： Local differential privacy Discrete distribution estimation Frequency estimation Multidimensional data Longitudinal studies

Guillaume Broux-Quemerais,Sarah Kaakai, Anis Matoussi,Wissal Sabbagh

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Probability, Uncertainty and Quantitative Risk 2024年第2期9卷 149-180页

作者： Guillaume Broux-Quemerais Sarah Kaakarl Anis Matoussi Wissal Sabbagh Laboratoire Manceau de Mathematiques&FR CNRS No 2962 Institut du Risque et de I'AssuranceLeMansUniversityFrance Centre de Mathématiques Appliquees(CMAP) CNRSEcole polytechniqueInstitut Polytechnique de Paris91120 PalaiseauFrance

In this paper,we present a probabilistic numerical method for a class of forward utilities in a stochastic factor *** this purpose,we use the representation of forward utilities using the ergodic Backward Stochastic Differential Equations(eBSdes)introduced by Liang and Zariphopoulou in[27].We establish a connection between the solution of the ergodic BSde and the solution of an associated BSde with random terminal time T,defined as the hitting time of the positive recurrent stochastic *** viewpoint based on BSdes with random horizon yields a new characterization of the ergodic cost^which is a part of the solution of the *** particular,for a certain class of eBSdes with quadratic generator,the cole-Hopf transformation leads to a semi-explicit representation of the solution as well as a new expression of the ergodic cost>.The latter can be estimated with Monte Carlo *** also propose two new deep learning numerical schemes for ***,we present numerical results for different examples of eBSdes and forward utilities together with the associated investment strategies.

关键词： deep leaming scheme Forward utilities Ergodic BSdes Markovian solution deep learning algorithm

Semi-solid processing of hypereutectic A390 alloys using novel rheoforming process

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Transactions of Nonferrous Metals Society of China 2010年第9期20卷 1743-1748页

作者： M.TEBIB J.B.MORIN F.A JERSCH X.GRANT CHEN Université du Québec à Chicoutimi cole polytechnique de montréal

The feasibility of semi solid processing of hypereutectic A390 alloys using a novel rheoforming process was investigated. A combination of the swirl enthalpy equilibration device （SEED） process, isothermal holding using insulation and addition of solid alloy during swirling was introduced as a novel method to improve the processability of semi solid slurry. The effects of isothermal holding and the addition of solid alloy on the temperature gradient between the centre and the wall and on the formation of a（al） particles were examined. In additional tests, phosphorus and strontium were added to the molten metal to refine the primary and eutectic silicon structure to facilitate semi solid processing. The results show that the combination of the SEED process with two additional processing steps can produce semi-solid A390 alloys that can be rheoprocessed. The microstructure reveals an adequate amount of non-dendritic a（al） globules surrounded by liquid, which greatly improves the processability of semi-solid slurry.

关键词： semi-solid forming rheoforming process hypereutectic A390 alloys microstructure

A numerical evaluation of continuous backfilling in cemented paste backfilled stope through an application of wick drains

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International Journal of Mining Science and Technology 2015年第6期25卷 897-904页

作者： Li Li Yang Pengyu department of Civil Geological and Mining Engineering école Polytechnique de Montréal

Cemented paste backfill （CPB） is gaining popularity in many underground mines worldwide. Sufficient water is added into CPB to make a flowable material for pipe transportation. Barricades are built near the drawpoints to prevent in-rush of the fill slurry. To avoid barricade failures resulting from excessive backfill pressures, backfilling is typically performed with a plug pour followed by a final pour. The interval between the two pours should be shortened or removed to increase mining productivity and avoid pipe clogging. Recently, Li proposed to apply wick drains in backfilled stopes to promote drainage and consolidation. The preliminary simulations by considering an instantaneous filling indicated that the drainage of CPB can be significantly accelerated by using wick drains. Barricade was not considered. Here, some new numerical modeUings are presented with more representative filling sequences, stope geometry, and different draining configurations. The results illustrate that the stope can be backfilled continuously by using wick drains.

关键词： Mines Cemented paste backfill Backfilled stopes Numerical analyses Drainage Wick drains

Numerical investigation of the stresses in backfilled stopes overlying a sill mat

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Journal of Rock Mechanics and Geotechnical Engineering 2017年第3期9卷 108-119页

作者： Mohamed Amine Sobhi Li Li Research Institute on Mines and the Environment Department of Civil Geological and Mining Engineering école Polytechnique de Montréal MontréalCanada

Backfill is commonly used in underground mines to help increase the ore recovery rate and reduce the ore dilution. The use of a part of mine waste as underground backfill material also helps reduce the environmental impact of mining operations. After all, backfill is used to provide a working platform or safer working space. Its primary and most important role is to improve the rock mass stability around mine openings. However, most available solutions to stress analyses were developed for an isolated stope, without taking into account the influence of mine depth, or of adjacent stopes. In this paper,results from a numerical study carried out to evaluate the stresses in backfilled stopes overlying a sill mat are presented. Mine depth and excavation of the underlying stope below the sill mat(horizontal pillar)are both taken into consideration. The influence of stope geometry, backfill, sill mat and rock properties on the stresses is also evaluated. Compared with the case of a single isolated backfilled stope, the numerical results show that the stress magnitudes in the overlying backfill are considerably increased due to the excavation of the underlying stope. In general, the stresses also increase with mine depth and backfill stiffness, while these tend to decrease with an increase in the surrounding rock mass *** results suggest that existing solutions for backfill design may need to be revised.

关键词： Mine depth Backfill Sill mat Stresses Numerical modeling