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Truly optimal semi-active damping to control free vibration of a single degree of freedom system

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Theoretical & Applied Mechanics Letters 2024年第2期14卷 142-145页

作者： Viet Duc la Ngoc Tuan Nguyen Institute of Mechanics Vietnam Academy of Science and TechnologyHanoi 10000Vietnam graduate University of Science and Technology Vietnam Academy of Science and TechnologyHanoi 10000Vietnam

This paper studies a single degree of freedom system under free vibration and controlled by a general semiactive damping.A general integral of squared error is considered as the performance index.A one-time switching damping controller is proposed and *** pontryagin maximum principle is used to prove that no other form of semi-active damping can provide the better performance than the proposed one-time switching damping.

关键词： Analytical optimization Quadratic integral Lyapunov equation Pontryagin maximum principle

A convolutional neural network to detect possible hidden data in spatial domain images

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Cybersecurity 2024年第1期7卷 37-52页

作者： Jean De la Croix Ntivuguruzwa Tohari Ahmad Department of Informatics Institut Teknologi Sepuluh Nopember(ITS)Kampus ITS Keputih SukoliloSurabaya60111Indonesia African Center of Excellence in the Internet of Things College of Science and TechnologyUniversity of Rwanda3900KigaliRwanda

Hiding secret data in digital multimedia has been essential to protect the ***,attackers with a steganalysis technique may break *** steganalysis methods have good results with conventional Machine Learning(ML)techniques;however,the introduction of Convolutional Neural Network(CNN),a deep learning paradigm,achieved better performance over the previously proposed ML-based *** the existing CNN-based approaches yield good results,they present performance issues in classification accuracy and stability in the network training *** research proposes a new method with a CNN architecture to improve the hidden data detection accuracy and the training phase stability in spatial domain *** proposed method comprises three phases:pre-processing,feature extraction,and ***,in the pre-processing phase,we use spatial rich model filters to enhance the noise within images altered by data hiding;secondly,in the feature extraction phase,we use two-dimensional depthwise separable convolutions to improve the signal-to-noise and regular convolutions to model local features;and finally,in the classification,we use multi-scale average pooling for local features aggregation and representability enhancement regardless of the input size variation,followed by three fully connected layers to form the final feature maps that we transform into class probabilities using the softmax *** results identify an improvement in the accuracy of the considered recent scheme ranging between 4.6 and 10.2%with reduced training time up to 30.81%.

关键词： Information security Spatial domain steganalysis Deep learning Convolutional neural network Infrastructure

Hydroxyapatite composites with carbon allotropes:Preparation,properties,and applications

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Particuology 2024年第5期88卷 239-265页

作者： Boris I.Kharisov Oxana V.Kharissova Lucy T.gonzález yolanda Peña Méndez Igor E.Uflyand Idalia gómez de la Fuente Universidad Autónoma de Nuevo León Ave.UniversidadCiudad UniversitariaSan Nicolás de los GarzaNuevo León 66455Mexico Tecnologico de Monterrey Escuela de Ingeniería y CienciasMonterreyNuevo Leon 64890Mexico Department of Chemistry Southern Federal UniversityRostov-on-DonRussia

Hydroxyapatite(HA)and its composites with inorganic additives,dopants,and polymers is a rapidly developing branch in the materials *** particular,carbon allotropes are widely used in these composites being widely applied for medical *** a gap of insufficient generalization of recent achievements in the field of the HA/Carbon composites,in this review we present the state of the art of the field of HA composites and hybrids with classic carbon allotropes and *** composites are known for carbon nanotubes,nanofibers,graphene and its oxidized forms,as well as,in a lesser grade,for graphite,fullerenes,nanodiamonds,carbon nanofoams,*** composites can be fabricated by a variety of classic and less-common methods,such as co-precipitation(with or without ultrasonic treatment),CVD,hot isostatic pressing,hydrothermal,spark plasma sintering,biomimetic mineralization,thermal and plasma spray,electrochemical and electrophoretic deposition,self-assembling,3D printing,electrospinning,and lyophilisation,among *** of various synthesis techniques can be also carried out for composite *** or synthetic HA can be used as it is for further interaction with carbon allotropes or it can be first prepared and then reacted with carbon counterpart;similarly,carbon allotropes can be introduced into the interaction with HA directly or they can be first synthesized,in particular from *** biocompatible composites can be produced in the form of coatings,powders,and scaffolds and can additionally contain quantitative amounts of third phases,frequently natural or synthetic *** these composites,especially with O-containing functionalizing groups,HA disadvantages could be considerably decreased with simultaneous enhancement of mechanical properties,becoming similar to human bone,chemical stability and biocompatibility,as well as possessing antibacterial ***→g reduction and higher HA decoration were obs

关键词： Hydroxyapatite Carbon nanotubes graphene Quantum dots Fullerenes Nanodiamonds

ZnSb/Ti_(3)C_(2)T_(x)MXene van der Waals heterojunction for flexible near-infrared photodetector arrays

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Journal of Semiconductors 2024年第5期45卷 99-105页

作者： Chuqiao Hu Ruiqing Chai Zhongming Wei la Li guozhen Shen State Key laboratory for Superlattices and Microstructures Institute of SemiconductorsChinese Academy of SciencesBeijing 100083China Center of Materials Science and Optoelectronic Engineering University of Chinese Academy of SciencesBeijing 100049China School of Integrated Circuits and Electronics Beijing Institute of TechnologyBeijing 100081China

Two-dimension(2D)van der Waals heterojunction holds essential promise in achieving high-performance flexible near-infrared(NIR)***,we report the successful fabrication of ZnSb/Ti_(3)C_(2)T_(x)MXene based flexible NIR photodetector array via a facile photolithography *** single ZnSb/Ti_(3)C_(2)T_(x)photodetector exhibited a high light-to-dark current ratio of 4.98,fast response/recovery time(2.5/1.3 s)and excellent stability due to the tight connection between 2D ZnSb nanoplates and 2D Ti_(3)C_(2)T_(x)MXene nanoflakes,and the formed 2D van der Waals *** polyethylene terephthalate(PET)substrate enables the ZnSb/Ti_(3)C_(2)T_(x)photodetector withstand bending such that stable photoelectrical properties with non-obvious change were maintained over 5000 bending ***,the ZnSb/Ti_(3)C_(2)T_(x)photodetectors were integrated into a 26×5 device array,realizing a NIR image sensing application.

关键词： ZnSb nanoplates Ti_(3)C_(2)T_(x)MXene van der Waals heterojunction flexible photodetector image sensing

Low-power SiPM readout BETA ASIC for space applications

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Nuclear Science and Techniques 2024年第3期35卷 153-169页

作者： Anand Sanmukh Sergio gómez Albert Comerma Joan Mauricio Rafel Manera Andreu Sanuy Daniel guberman Roger Catala Albert Espinya Marina Orta Oscar de la Torre David gascon Departament de Física Quàntica i Astrofísica(FQA) Institut de Ciències del Cosmos(ICCUB)Universitat de Barcelona(UB)08028 BarcelonaSpain Institut d’Estudis Espacials de Catalunya(IEEC) 08034 BarcelonaSpain Electronics Department Serra Hunter fellow at Polytechnic University of Catalonia(UPC)08019 BarcelonaSpain

The BETA application-specific integrated circuit(ASIC)is a fully programmable chip designed to amplify,shape and digitize the signal of up to 64 Silicon photomultiplier(SiPM)channels,with a power consumption of approximately~1 mW/*** to its dual-path gain,the BETA chip is capable of resolving single photoelectrons(phes)with a signal-to-noise ratio(SNR)>5 while simultaneously achieving a dynamic range of~4000 ***,BETA can provide a cost-effective solution for the readout of SiPMs in space missions and other applications with a maximum rate below 10 *** this study,we describe the key characteristics of the BETA ASIC and present an evaluation of the performance of its 16-channel version,which is implemented using 130 nm *** ASIC also contains two discriminators that can provide trigger signals with a time jitter down to 400 ps FWHM for 10 *** linearity error of the charge gain measurement was less than 2%for a dynamic range as large as 15 bits.

关键词： Radiation detectors Silicon photomultipliers Photon sensors Front-end electronics Mixed-mode ASICs Space technology

High Seebeck Coefficient Thermally Chargeable Supercapacitor with Synergistic Effect of Multichannel Ionogel Electrolyte and Ti3C2Tx MXene-Based Composite Electrode

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ENERgy & ENVIRONMENTAL MATERIALS 2024年第6期7卷 367-377页

作者： Chen, Zhongming Du, Zhijian Li, la Jiang, Kai Chen, Di Shen, guozhen Univ Sci & Technol Beijing Sch Math & Phys Beijing 100083 Peoples R China Beijing Inst Technol Sch Integrated Circuits & Elect Beijing 100081 Peoples R China Chinese Pla Chinese PLA Gen Hosp Inst Hepatobiliary Surg Chinese PLA Fac Hepatopancreato Biliary Surg Beijing 100853 Peoples R China Chinese Pla Key Lab Digital Hepetobiliary Surg Beijing 100853 Peoples R China

Thermally chargeable supercapacitors can collect low-grade heat generated by the human body and convert it into electricity as a power supply unit for wearable electronics. However, the low Seebeck coefficient and heat-to-electricity conversion efficiency hinder further application. In this paper, we designed a high-performance thermally chargeable supercapacitor device composed of ZnMn2O4@Ti3C2Tx MXene composites (ZMO@Ti3C2Tx MXene) electrode and UIO-66 metal-organic framework doped multichannel polyvinylidene fluoridehexafluoro-propylene ionogel electrolyte, which realized the thermoelectric conversion and electrical energy storage at the same time. This thermally chargeable supercapacitor device exhibited a high Seebeck coefficient of 55.4 mV K-1, thermal voltage of 243 mV, and outstanding heat-to-electricity conversion efficiency of up to 6.48% at the temperature difference of 4.4 K. In addition, this device showed excellent charge-discharge cycling stability at high-temperature differences (3 K) and low-temperature differences (1 K), respectively. Connecting two thermally chargeable supercapacitor units in series, the generated output voltage of 500 mV further confirmed the stability of devices. When a single device was worn on the arm, a thermal voltage of 208.3 mV was obtained indicating the possibility of application in wearable electronics.

关键词： ionogel electrode Soret effect thermally chargeable supercapacitor Ti3C2Tx MXene UIO-66 MOF gELS

The Influence of Significant Public Health Events on Offline Consumption and Its Pathways

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Journal of Systems Science and Systems Engineering 2024年第5期33卷 627-648页

作者： Baile Lu Kewei Zhou Shuai Hao la Ta Hongyan Dai Weihua Zhou College of Systems Engineering National University of Defense TechnologyChangsha 410073China Business School Central University of Finance and EconomicsBeijing 100081China Department of Marketing and Operations Management College of BusinessSouthern University of Science and TechnologyShenzhen 518055China School of Management Zhejiang UniversityHangzhou 310058China

In the face of a significant public health event,consumers may either increase their panic buying or decrease their willingness to make *** study focuses on the impact of a significant public health event on offline store sales and consumer consumption,utilizing data from chain convenience stores in Hefei and Wuhu during early 2019 and early 2020 in *** a difference-in-differences model,the study investigates the effect of the significant public health event outbreak on weekly store sales,order numbers,and consumer consumption in terms of product quantities,transaction amount,average amount per order,and transaction *** from prior literature that finds hoarding behavior of consumers online,the findings of this paper indicate a significant reduction in stores’offline weekly sales and order numbers,as well as consumers’offline weekly consumption across the four dimensions,as a result of the significant public health event ***,employing a mediation model,the study explores the pathway of population mobility through which the significant public health event adversely affects offline ***,subset analysis is conducted for stores located in different areas and consumers with varying characteristics,revealing that the aforementioned conclusions predominantly apply to stores situated in office areas and residential areas,as well as consumers with either no apparent preference for different product categories or a noticeable preference for food.

关键词： Significant public health event offline consumption population mobility mediating effect

Polarization Study of Swift J151857.0–572147 with IXPE Observation

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Research in Astronomy and Astrophysics 2024年第9期24卷 60-65页

作者： yu-Shan Ling Fei Xie Ming-yu ge Fabio la Monaca guangxi Key laboratory for Relativistic Astrophysics School of Physical Science and TechnologyGuangxi UniversityNanning 530004China Key laboratory of Particle Astrophysics Institute of High Energy PhysicsChinese Academy of SciencesBeijing 100049China INAF Istituto di Astrofisica e Planetologia Spaziali Via del Fosso del Cavaliere 10000133 RomaItaly Dipartimento di Fisica Universitàdegli Studi di Roma“Tor Vergata”Via della Ricerca Scientifica 100133 RomaItaly Dipartimento di Fisica Universitàdegli Studi di Roma“La Sapienza”Piazzale Aldo Moro 500185 RomaItaly

We present an analysis of the Imaging X-ray Polarimetry Explorer observation from a newly discovered transient source:Swift *** obtained polarization degree(PD)and angle are 0.3%±0.3% and -24°±26°respectively in 2-8 keV within 68%confidence level errors,and polarization results are below MDP99in all energy bins,with the upper limit on PD of 0.8% in the 2-8 keV energy *** quasi-periodic oscillations(QPOs)are detected in this *** polarization and QPO analyses support the hypothesis that the source was in the high soft state,and the results are consistent with predictions for a thin accretion disk model.

关键词： stars:black holes polarization X-rays:bursts

Challenges and pitfalls of youth-onset type 2 diabetes

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World Journal of Diabetes 2024年第5期15卷 876-885页

作者： lavinia la grasta Sabolic Sanda Marusic Maja Cigrovski Berkovic Department of Pediatric Endocrinology and Diabetology University Hospital Centre Sestre MilosrdniceZagreb 10000Croatia School of Medicine Catholic University of CroatiaZagreb 10000Croatia Department for Sport and Exercise Medicine University of Zagreb Faculty of KinesiologyZagreb 10000Croatia

The incidence and prevalence of youth-onset type 2 diabetes mellitus(T2DM)are *** rise in frequency and severity of childhood obesity,inclination to sedentary lifestyle,and epigenetic risks related to prenatal hyperglycemia exposure are important drivers of the youth-onset T2DM epidemic and might as well be responsible for the early onset of diabetes ***,youth-onset T2DM has a more extreme metabolic phenotype than adult-onset T2DM,with greater insulin resistance and more rapid deterioration of beta cell ***,intermediate complications such as microalbuminuria develop in late childhood or early adulthood,while end-stage complications develop in *** to the lack of efficacy and safety data,several drugs available for the treatment of adults with T2DM have not been approved in youth,reducing the pharmacological treatment *** this mini review,we will try to address the present challenges and pitfalls related to youth-onset T2DM and summarize the available interventions to mitigate the risk of microvascular and macrovascular complications.

关键词： youth-onset type 2 diabetes mellitus Insulin resistance Beta cell failure Risk factors Therapy Complications