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theoretical and experimental studies of gas preparation system for pressurization and reactive control system of launch vehicle

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Chinese Journal of Aeronautics 2024年第7期37卷 168-177页

作者： Valeriy tRUSHLYAKOV Vladislav URBANSKY Vadim YUDINtSEV Department of Aviation and Rocket Building Omsk State Technical UniversityOmsk 644050Russia

A new gas preparation system(GasPS-RCS)is proposed to solve two tasks:(A)to heat helium gas for tank pressurization;(B)to prepare gas for the Launch Vehicle(LV)Reactive Control System(RCS)at the LV orientation and stabilization sections of the LV on passive parts of the flight trajectory,to provide conditions for launching the Liquid Rocket Engine(LRE).the system includes a gas generator based on hydrogen peroxide,a separator for water separation,heat exchangers independent of the LRE,and gas-jet *** proposed new system allowed to reduce the length of pressurizing gas lines and reduce the increased helium gas consumption during the heat exchanger warm-up interval of the LRE during its launch.A special advantage of the proposed system is the possibility of ground testing of heat exchangers without an operating LRE.A mathematical model based on the first law of thermodynamics was used to perform a comparative analysis of GasPS-RCS with traditional pressurization and RCS *** validate the mathematical model,the experimental studies of helium pressurizing of a liquid nitrogen tank were *** results show that the deviation of experimental and calculated values for pressure is 1.1%and for temperature up to 2%.According to the results of comparative analysis,the GasPS-RCS is 259 kg lighter for the first stage and 80 kg lighter for the second stage of the LV.

关键词： Engine restart Reactive control system tank pressurization Cryogenics Hydrogen peroxide Heat exchanger

Dynamic Forecasting of traffic Event Duration in Istanbul:A Classification Approach with Real-time Data Integration

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Computers, materials & Continua 2024年第8期80卷 2259-2281页

作者： mesut Ulu Yusuf Sait türkan Kenan menguc Ersin Namlı tarık Kucukdeniz Occupational Health and Safety Department Bandirma Onyedi Eylul UniversityBalikesir10200Türkiye Department of Industrial Engineering Istanbul University-CerrahpasaIstanbul34320Türkiye Department of Industrial Engineering Istanbul Technical UniversityIstanbul34467Türkiye

today,urban traffic,growing populations,and dense transportation networks are contributing to an increase in traffic *** incidents include traffic accidents,vehicle breakdowns,fires,and traffic disputes,resulting in long waiting times,high carbon emissions,and other undesirable *** is vital to estimate incident response times quickly and accurately after traffic incidents occur for the success of incident-related planning and response *** study presents a model for forecasting the traffic incident duration of traffic events with high *** proposed model goes through a 4-stage process using various features to predict the duration of four different traffic events and presents a feature reduction approach to enable real-time data collection and *** the first stage,the dataset consisting of 24,431 data points and 75 variables is prepared by data collection,merging,missing data processing and data *** the second stage,models such as Decision trees(Dt),K-Nearest Neighbour(KNN),Random Forest(RF)and Support Vector machines(SVm)are used and hyperparameter optimisation is performed with *** the third stage,feature selection and reduction are performed and real-time data are *** the last stage,model performance with 14 variables is evaluated with metrics such as accuracy,precision,recall,F1-score,mCC,confusion matrix and *** RF model outperforms other models with an accuracy of 98.5%.the study’s prediction results demonstrate that the proposed dynamic prediction model can achieve a high level of success.

关键词： traffic event duration forecasting machine learning feature reduction shapley additive explanations(SHAP)

A Golden touch in the Design of multifunctional Porphyrin metallacages:Host-Guest Chemistry for Drug-target Interactions

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CCS Chemistry 2024年第7期6卷 1662-1671页

作者： tamara Rodríguez-Prieto Darren Wragg Nicole Heiduk mihyun Park Nicole Strittmatter Roland A.Fischer Angela Casini Guillermo moreno-Alcántar Chair of medicinal and Bioinorganic Chemistry Department of ChemistrySchool of Natural SciencesTechnical University of Munich85748 Garching b.München Professorship for Analytical Chemistry Department of ChemistrySchool of Natural SciencesTechnical University of Munich85748 Garching b.München Chair of Inorganic and metalOrganic Chemistry Department of ChemistrySchool of Natural SciencesTechnical University of Munich85748 Garching b.München munich Data Science Institute(mDSI) Technical University of Munich85748 Garching b.München

the use of three-dimensional self-assembled metallacages(mCgs)as multimodal drug platforms holds great ***,the synthesis of mCgs with increased complexity and functionality is a great challenge since understanding of the interaction of mCgs with biological targets is still *** this context,this work reports on the integration of a gold(III)porphyrin scaffold into a prismatic mCg structure and explores its application for multimodal therapy of cancer in vitro,namely enabling both photodynamic therapy and *** experimental approaches with a state-of-the-art metadynamics theoretical study,we discovered that the gold cage shows unprecedented host-guest interaction-driven selective stabilization of guanine-quadruplex(G4)structures-validated anticancer drug targets-disclosing a new mechanism to pursue in the design of supramolecular drugs.

关键词： gold metallacages porphyrins G4stabili-zation host-guestchemistry anticanceragents

On-Chip micro temperature Controllers Based on Freestanding thermoelectric Nano Films for Low-Power Electronics

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Nano-micro Letters 2024年第7期16卷 98-108页

作者： Qun Jin tianxiao Guo Nicolas Perez Nianjun Yang Xin Jiang Kornelius Nielsch Heiko Reith Institute for metallic materials Leibniz Institute for Solid State and Materials Research01069 DresdenGermany Institute of materials Engineering University of Siegen57076 SiegenGermany Institute of Applied Physics Technical University of Dresden01069 DresdenGermany Institute of materials Science Technical University of Dresden01069 DresdenGermany

multidimensional integration and multifunctional com-ponent assembly have been greatly explored in recent years to extend moore’s Law of modern ***,this inevitably exac-erbates the inhomogeneity of temperature distribution in microsystems,making precise temperature control for electronic components extremely ***,we report an on-chip micro temperature controller including a pair of thermoelectric legs with a total area of 50×50μm^(2),which are fabricated from dense and flat freestanding Bi2te3-based ther-moelectric nano films deposited on a newly developed nano graphene oxide membrane *** tunable equivalent thermal resistance is controlled by electrical currents to achieve energy-efficient temperature control for low-power electronics.A large cooling temperature difference of 44.5 K at 380 K is achieved with a power consumption of only 445μW,resulting in an ultrahigh temperature control capability over 100 K mW^(-1).moreover,an ultra-fast cooling rate exceeding 2000 K s^(-1) and excellent reliability of up to 1 million cycles are *** proposed on-chip temperature controller is expected to enable further miniaturization and multifunctional integration on a single chip for microelectronics.

关键词： temperature control Low-power electronics On-chip micro temperature controller Freestanding thermoelectric nano films temperature-sensitive components

High-Energy tunable 6.5-12 μm Picosecond mid-Infrared Radiation Generated from Optical Parametric Amplifier Based on LiInSe2 Crystal

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激光与光电子学进展 2024年第13期61卷 467-472页

作者： Zhang Jingjing Wang Shilei Yang Feng Wang Shanpeng Gao Hongwei Bo Yong Cui Dafu tao Xutang Peng Qinjun Key Lab of Solid state Laser Technical Institute of Physics and Chemistry Chinese Academy of Sciences university of Chinese Academy of Sciences state Key Laboratory of Crystal materials Shandong University

We report high-energy tunable 6.5-12 μm ps mid-infrared radiation generation based on OPA pumped using 1064 nm laser in LISe *** simulated the relationship between the idler energy and crystal *** optimum LISe length of 4 mm was used to enhance the idler energy *** a pump energy of ～9.4 mJ, energy levels of ～146 and of ～27 μJ are generated at 6.5 μm and 12 μm, *** highest energy of ～205 μJ is achieved at 8.1 μm at a pump energy of ～19 ***, the angular and spectral width acceptance are measured.

关键词： LiInSe2 crystal nonlinear optical crystal optical parametric amplifier tunable mid-infrared radiation

method for passivation of propellant residues in orbital stage tank of launch vehicle

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Chinese Journal of Aeronautics 2024年第1期37卷 64-76页

作者： Valeriy tRUSHLYAKOV Ivan LESNYAK Alexey PANICHKIN Department of Aviation and Rocket Building Omsk State Technical UniversityOmsk 644050Russia Sobolev Institute of mathematics of the Siberian Branch of Russian Academy of Sciences Novosibirsk 630090Russia

the problem of removing unused liquid propellant residues from the tanks of spent spacecraft and orbital stages of Launch Vehicles(LV)leads to their explosion and the formation of space debris in *** provide a solution to this problem,a method for removing liquid propellant residues from the LV tanks after the mission completion is *** method is based on the gasification of liquid propellant residues in the tanks under acoustic-vacuum exposure and the discharge of the gasification products into the surrounding outer *** investigations were carried out on a Ground-based Experimental Installation(GEI)to determine the coefficient of heat transfer from the surface of an acoustic radiator to a *** obtained coefficient was then used to calculate the energy costs for the gasification of *** estimates are given on the example of the tank with kerosene residues from a spent second stage of the LV“Soyuz-2.1 v”.the optimal discharge rate at which kerosene does not freeze is 0.14 m^(3)/***,the acoustic exposure leads to an increase in the mass of evaporated kerosene over a given time by96.1%,and the energy costs are 1756.7 kJ(approximately 50% of the remaining electrical energy).

关键词： Propellant Weightlessness Liquid evaporation Heat and mass transfer Acoustics Vacuum Vapor bubbles

Gust response of an elasto-flexible morphing wing using fluid–structure interaction simulations

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Chinese Journal of Aeronautics 2024年第2期37卷 45-57页

作者： Jonathan PFLÜGER Christian BREItSAmtER Department of mechanical Engineering Technical University of MunichGarching 85748Germany

Small and micro unmanned aircraft are the focus of scientific interest due to their wide range of *** often operate in a highly unstable flight environment where the application of new morphing wing technologies offers the opportunity to improve flight *** investigated concept comprises port and starboard adjustable wings,and an adaptive elastoflexible membrane serves as the lifting *** focus is on the benefits of the deforming membrane during the impact of a one-minus-cosine type *** a low Reynolds number of Re=264000,the morphing wing model is investigated numerically by unsteady fluid-structure interaction ***,the numerical results are validated by experimental data from force and moment,flow field,and deformation ***,with the rigid wing as the baseline,the flexible case is investigated,focusing on the advantages of the elastic *** all configurations studied,the maximum amplitude of the lift coefficient under gust load shows good agreement between the experimental and numerical *** the decay of the gust,they differ more the higher the aspect ratio of the *** considering the flow field,the main differences are due to the separation behavior on the upper side of the *** flow reattaches earlier in the experiments than in the simulations,which explains the higher lift values observed in the *** at one intermediate configuration does the lift amplitude of the rigid configuration exceeds that of the flexible by about 12%,with the elastic membrane resulting in a smaller and more uniform peak load,which is also evident in the wing loading and hence in the root bending moment.

关键词： membrane wing morphing wing Flexible wing surface Computational fluid dynam-ics Fluid-structure interaction Unsteady inflow condition Gust response

A robust optimization method for label noisy datasets based on adaptive threshold: Adaptive-k

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Frontiers of Computer Science 2024年第4期18卷 49-60页

作者： Enes DEDEOGLU Himmet toprak KESGIN mehmet Fatih AmASYALI Department of Computer Engineering Yildiz Technical UniversityIstanbul 34220Turkey

the use of all samples in the optimization process does not produce robust results in datasets with label *** the gradients calculated according to the losses of the noisy samples cause the optimization process to go in the wrong *** this paper,we recommend using samples with loss less than a threshold determined during the optimization,instead of using all samples in the *** proposed method,Adaptive-k,aims to exclude label noise samples from the optimization process and make the process *** noisy datasets,we found that using a threshold-based approach,such as Adaptive-k,produces better results than using all samples or a fixed number of low-loss samples in the *** the basis of our theoretical analysis and experimental results,we show that the Adaptive-k method is closest to the performance of the Oracle,in which noisy samples are entirely removed from the ***-k is a simple but effective *** does not require prior knowledge of the noise ratio of the dataset,does not require additional model training,and does not increase training time *** the experiments,we also show that Adaptive-k is compatible with different optimizers such as SGD,SGDm,and *** code for Adaptive-k is available at GitHub.

关键词： robust optimization label noise noisy label deep learning noisy datasets noise ratio estimation robust training

Investigation of micro-scale shear response of sand–rubber granule mixture in terms of particle shape and grain scale deformability effects

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Particuology 2024年第7期90卷 452-469页

作者： Abdulmuttalip Ari Suat Akbulut Department of Civil Engineering Yildiz Technical UniversityIstanbul34220Turkey

In this study,the effects of particle shape of rigid sand and soft rubber materials on macro-scale shear response were reasoned based on micro-scale *** this purpose,first,the shape properties of three different sand and two different rubber samples were quantified using image processing techniques,and the contact model parameters were calibrated through physical *** direct shear test was simulated in a two-dimensional discrete element software with realistic particle *** soft nature of rubber particles was reflected using body-centered cubic packing with a linear-parallel bond contact *** a result,coordination number,distribution of contact forces(i.e.,strong contact,and fabric anisotropy),and contact sliding were derived by the numerical *** has been observed that the particle shape leads to distinctive micro-scale responses due to the variations in the stiffness of the contacts.

关键词： Particle shape Sand Rubber Shear response micro-scale response Discrete element method