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A systematic review of a digital twin city: A new pattern of urban governance toward smart cities

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Journal of Management Science and Engineering 2021年第2期6卷 125-134页

作者： Tianhu Deng Keren Zhang Zuo-Jun(max)shen Tsinghua University Beijing100084China University of California Berkeley BerkeleyCA94720United States

Many countries and governments consider smart cities a solution to global warming,population growth,and resource *** challenges arise while creating a smart *** twins,along with the Internet of Things,fifth-generation wireless systems,blockchain,collaborative computing,simulation,and artificial intelligence technologies,offer great potential in the transformation of the current urban governance paradigm toward smart *** this paper,the concept of a digital twin city(DTC)is *** characteristics,key technologies,and application scenarios of a DTC are elaborated ***,we discuss the theories,research directions,and framework regarding DTCs.

关键词： Digital twin Smart city Urban governance IoT Blockchain

Vibration-controlled Transient Elastography for Assessment of Liver Fibrosis at a USA Academic Medical Center

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Journal of Clinical and Translational Hepatology 2022年第2期10卷 197-206页

作者： max shen Anna Lee Jay H.Lefkowitch Howard J.Worman Department of Medicine Vagelos College of Physicians and SurgeonsColumbia UniversityNew YorkNYUSA Department of Pathology and Cell Biology Vagelos College of Physicians and SurgeonsColumbia UniversityNew YorkNYUSA

Background and Aims:Vibration-controlled transient elastography(VCTE)is a noninvasive tool that uses liver stiffness measurement(LSM)to assess *** real-life data during everyday clinical practice in the USA are lacking,we describe the patterns of use and diagnostic performance of VCTE in patients at an academic medical center in New York ***:Patients who received VCTE scans were included if liver biopsy was performed within 1 *** performance of VCTE in differentiating dichotomized fibrosis stages was assessed via area under the receiver operating characteristics(AUROC).Fibrosis stage determined from VCTE LSM was compared to liver ***:Of 109 patients,49 had nonalcoholic fatty liver disease,16 chronic hepatitis C,15 congestive hepatopathy,and 22 at least two *** was 0.90 for differentiating cirrhosis(stage 4)with a positive predictive value(PPV)range of 0.28 to 0.45 and negative predictive value range of 0.96 to *** 31(32%)patients,VCTE fibrosis stage was at least two stages higher than liver biopsy fibrosis *** of thirty-five pa-tients considered to have cirrhosis by VCTE had stage 0 to 2 and 12 stage 3 fibrosis on liver ***:VCTE has reasonable diagnostic accuracy and is reliable at ruling out ***,because of its low PPV,caution must be exercised when used to diagnose cirrhosis,as misdiagnosis can lead to unnecessary health care *** routine practice,VTCE is also sometimes performed for disease etiologies for which it has not been robustly validated.

关键词： Chronic liver disease Cirrhosis Hepatitis Liver histopathology Nonalcoholic fatty liver disease

Digital twin-driven smart supply chain

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Frontiers of Engineering Management 2022年第1期9卷 56-70页

作者： Lu WANG Tianhu DENG Zuo-Jun max shen Hao HU Yongzhi QI Department of Industrial Engineering Tsinghua UniversityBeijing 100084China Faculty of Engineering and Faculty of Business and Economics University of Hong KongHong Kong 999077China Department of Industrial Engineering and Operations Research and Department of Civil and Environmental Engineering University of CaliforniaBerkeleyBerkeleyCA 94720USA *** Beijing 100101China

Today’s supply chain is becoming complex and ***,supply chain managers need to create and unlock the value of the smart supply chain.A smart supply chain requires connectivity,visibility,and agility,and it needs be integrated and *** digital twin(DT)concept satisfies these ***,we propose creating a DT-driven supply chain(DTSC)as an innovative and integrated solution for the smart supply *** provide background information to explain the DT concept and to demonstrate the method for building a DTSC by using the DT *** discuss three research opportunities in building a DTSC,including supply chain modeling,real-time supply chain optimization,and data usage in supply chain ***,we highlight a motivating case from ***,China’s largest retailer by revenue,in applying the DTSC platform to address supply chain network reconfiguration challenges during the COVID-19 pandemic.

关键词： digital twin supply chain management

Rational Solutions of First Order Algebraic Ordinary Differential Equations

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Journal of Systems Science & Complexity 2024年第2期37卷 567-580页

作者： FENG Shuang shen Liyong School of Physical and Mathematical Sciences Nanjing Tech UniversityNanjing 211816China School of Mathematical Sciences University of Chinese Academy of SciencesBeijing 100049China

Let f(t,y,y')=∑ _(i=0)^(n )a_(i)(t,y)y'^(i)=0 be an irreducible first order ordinary differential equation with polynomial *** in 1998 proved that there exists a constant C such that every rational solution of f(t,y,y')=0 is of degree not greater than *** show that this degree bound C depends not only on the degrees of f in t,y,y' but also on the coefficients of f viewed as the polynomial in t,y,y'.In this paper,the authors show that if f satisfies deg(f,y)max i=0{deg(a_(i),y)−2(n−i)}>0,then the degree bound C only depends on the degrees of f in t,y,y',and furthermore we present an explicit expression for C in terms of the degrees of f in t,y,y'.

关键词： Degree bound first order AODE height rational solution

Large reversible magnetocaloric effect in antiferromagnetic Er_(3)Si_(2)C_(2) compound

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Journal of Rare Earths 2024年第8期42卷 1555-1559,I0005页

作者： Hao Sun Lu Tian Xinqiang Gao Zhaojun Mo Jun shen Baogen shen School of Rare Earths University of Science and Technology of ChinaHefei230026China Ganjiang Innovation Academy Chinese Academy of SciencesGanzhou341000China Department of Energy and Power Engineering School of Mechanical EngineeringBeijing Institute of TechnologyBeijing100081China

The magnetic properties,magnetic phase transition and magnetocaloric effects(MCE) of Er_(3)Si_(2)C_(2) compound were investigated based on theoretical calculations and experimental *** on the first principles calculations,the antiferromagnetic(AFM) ground state type in Er_(3)Si_(2)C_(2) compound was predicted and its electronic structure was *** experimental results show that Ei_(3)Si_(2)C_(2) compound is an AFM compound with the Neel temperature(T_(N) of 7 K and undergoes a field-induced firstorder magnetic phase transition from AFM to ferromagnetic(FM) under magnetic fields exceeding 0.6 T at 2 *** magnetic transition process of Er_(3)Si_(2)C_(2) compound was investigated and *** values of the maximum magnetic entropy change(-ΔS_(M)^(max)) and the refrigeration capacity(RC) are 17 J/(kg·K)and 193 J/kg under changing magnetic fields of 0-5 T,*** a potential cryogenic magnetic refrigerant,the Er_(3)Si_(2)C_(2) compound also provides an interesting research medium to study the magnetic phase transition process.

关键词： Magnetic materials Magnetocaloric Metamagnetic transitions Magnetic phase transition Rare earths

Solar energetic particles intensity variations associated with a tilted-dipole 3D corotating interaction region

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Earth and Planetary Physics 2024年第5期8卷 797-810页

作者： YuJi Zhu Fang shen Xi Luo Yang Wang BoFeng Tang State Key Laboratory of Space Weather National Space Science Center Chinese Academy of Sciences Shandong Institute of Advanced Technology (SDIAT) College of Earth and Planetary Sciences University of Chinese Academy of Sciences School of Science Harbin Institute of Technology

The effect of a tilted-dipole three-dimensional corotating interaction region(CIR) on the transport and acceleration of solar energetic particles(SEPs) is *** this work,we discussed how the particle intensity longitudinal and radial dependence might be influenced by the background ***,we investigate how the spectral index distribution is modulated by the CIR structure We use the focused transport equation(FTE) to describe the propagation and acceleration of SEPs in a tilt-dipole 3D CIR,generated by the high-resolution 3D magnetohydrodynamic(MHD) *** forward stochastic differential method is used to solve the *** protons with theE～(-4.4)spectrum from 0.5 to 15 MeV are injected uniformly at the heliographic equator of 0.15 *** quantities are extracted along each interplanetary magnetic field(IMF) line to show the *** the tilted-dipole CIR background,if injected from the solar equator at the inner boundary,particles in the slow flow are transported to higher latitudes due to the extension of the IMF lines to higher *** longitudinal patterns of the particles are dominated by the density of IMF *** focusing effect modulates the longitudinal variation of the particle intensity and gives rise to new longitudinal intensity *** adiabatic effect largely increases the intensity fluctuation along the *** structure of the solar wind can also lead to the difference of the index α in the empirical functionI＿(max)=kR～(-α),describing the radial variation of peak intensity according to our *** the influence of the CIR structure,the index α varies from 1.9 to 3.4 at 0.3-1.0 *** variation of the solar wind speed should be considered when estimating the radial dependence of the SEP peak *** spectra indices rise near the CIR boundaries and drop near the stream interface(SI).The adiabatic effect makes the spatial variability of the spectral index *** spectral index could be sim

关键词： solar energetic particle (SEP) corotating interaction regions (CIR) magnetohydrodynamic (MHD)

Fabricating functionally graded Fe-Cr-Co permanent magnetic alloys via laser powder bed fusion

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Journal of Iron and Steel Research International 2024年第3期31卷 729-737页

作者： Ya-zhou He Ya-qing Hou Peng shen Hao Zhang Dong Zhou Hang Su Central Iron and Steel Research Institute Co. Ltd.Beijing 100081China Material Digital R&D Center China Iron and Steel Research Institute Group Co.Ltd.Beijing 100081China

Laser powder bed fusion(LPBF)in-situ alloying technology offers the possibility to construct gradient materials with varied structures and *** graded Fe-Cr-Co permanent magnetic alloys were fabricated by LPBF and in-situ alloying mixed powders of Fe,Cr,and Co *** effects of different Fe,Cr and Co contents on the microstructure,magnetic properties and hardness of Fe-Cr-Co alloys prepared by LPBF were *** as-built Fe-Cr-Co alloys present a single body-centered-cubic phase and have a homogeneous distribution of *** mechanical properties and magnetic properties of the compositionally graded sample show a gradient *** the increase in Cr content,the Vickers hardness of the sample increases,and the saturation magnetization of the sample *** optimal magnetic properties in an isotropic state are given as coercivity HcB=21.65 kA/m,remanence Br=0.70 T and energy product(BH)_(max)=5.35 kJ/m^(3),which are comparable to or higher than the reported magnetic properties in an isotropic state prepared by traditional powder *** in-situ alloying technology has the potential to further explore Fe-Cr-Co magnetic materials,such as those consisting of multiple or more constituent elements,and to maximize the compositional flexibility of magnetic materials.

关键词： Fe-Cr-Co alloy Laser powder bed fusion In-situ alloying Functional material Magnetic property

Magnetic properties and magnetocaloric effects in Eu(Ti,Nb,Mn)O_(3) perovskites

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Journal of Rare Earths 2024年第8期42卷 1560-1567,I0006页

作者： Junfeng Wang Huicai Xie Quanyi Liu Zhihong Hao Zhaojun Mo Qi Fu Xinqiang Gao Jun shen Ganjiang Innovation Academy Chinese Academy of SciencesGanzhou341119China Faculty of Materials Metallurgy and Chemistry Jiangxi University of Science and TechnologyGanzhou341000China School of Rare Earth and New Materials Engineering Gannan University of Science and TechnologyGanzhou341000China Department of Energy and Power Engineering School of Mechanical EngineeringBeijing Institute of TechnologyBeijing100081China

In perovskite EuTiO_(3),the magnetic characteristics and magnetocaloric effect(MCE) can be flexibly regulated by converting the magnetism from antiferromagnetic to *** the present work,a series of Eu(Ti,Nb,Mn)O_(3) compounds,abbreviated as ETNMO for convenience of description,was fabricated and their crystallography,magnetism together with cryogenic magnetocaloric effects were systematically *** crystallographic results demonstrate the cubic perovskite structure for all the compounds,with the space group of *** magnetic phase transitions are observed in these second-order phase transition(SOPT) *** joint substitution of elements Mn and Nb can considerably manipulate the magnetic phase transition process and magnetocaloric performance of the ETNMO *** the Mn content increases,gradually widened-ΔS_(M)-T curves are obtained,and two peaks with a broad shoulder are observed in the-ΔS_(M)-T curves for Δμ_(0)H≤0-1 *** a field change of 0-5 T,the values of maximum magnetic entropy change(-ΔS_(M)^(max)) and refrigeration capacity(RC) are evaluated to be 34.7 J/(kg·K) and 364.9 J/kg for EuTi_(0.8625)Nb_(0.0625)Mn_(0.075)O_(3), 27.8 J/(kg·K) and367.6 J/kg for EuTi_(0.8375)Nb_(0.0625)Mn_(0.1)O_(3),23.2 J/(kg·K) and 369.2 J/kg for EuTi_(0.8125)Nb_(0.0625)Mn_(0.125)O_(3),17.1 J/(kg·K) and 357.6 J/kg for EuTi_(0.7875)Nb_(0.0625)Mn_(0.15)O_(3),*** co nsiderable MCE parameters make the ETNMO compounds potential candidates for cryogenic magnetic refrigeration.

关键词： ETNMO perovskites Cryogenic refrigeration Magnetic phase transition Magnetocaloric effect Rare earths

Detecting XSS with Random Forest and Multi-Channel Feature Extraction

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Computers, Materials & Continua 2024年第7期80卷 843-874页

作者： Qiurong Qin Yueqin Li Yajie Mi Jinhui shen Kexin Wu Zhenzhao Wang Smart City College Beijing Union UniversityBeijing100101China

In the era of the Internet,widely used web applications have become the target of hacker attacks because they contain a large amount of personal *** these vulnerabilities,stealing private data through crosssite scripting(XSS)attacks is one of the most commonly used attacks by ***,deep learning-based XSS attack detection methods have good application prospects;however,they suffer from problems such as being prone to overfitting,a high false alarm rate,and low *** address these issues,we propose a multi-stage feature extraction and fusion model for XSS detection based on Random Forest feature *** model utilizes RandomForests to capture the intrinsic structure and patterns of the data by extracting leaf node indices as features,which are subsequentlymergedwith the original data features to forma feature setwith richer information *** feature extraction is conducted through three parallel *** I utilizes parallel onedimensional convolutional layers(1Dconvolutional layers)with different convolutional kernel sizes to extract local features at different scales and performmulti-scale feature fusion;Channel II employsmaximum one-dimensional pooling layers(max 1D pooling layers)of various sizes to extract key features from the data;and Channel III extracts global information bi-directionally using a Bi-Directional Long-Short TermMemory Network(Bi-LSTM)and incorporates a multi-head attention mechanism to enhance global ***,effective classification and prediction of XSS are performed by fusing the features of the three *** test the effectiveness of the model,we conduct experiments on six *** achieve an accuracy of 100%on the UNSW-NB15 dataset and 99.99%on the CICIDS2017 dataset,which is higher than that of the existing models.

关键词： Random forest feature enhancement three-channel parallelism XSS detection