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| 1 | Random dynamic analysis of vertical train–bridge systems under small probability by surrogate model and subset simulation with splitting显示文摘The response of the train–bridge system has an obvious random behavior.A high traffic density and a long maintenance period of a track will result in a substantial increase in the number of trains running on a bridge,and there is small likelihood that the maximum responses of the train and bridge happen in the total maintenance period of the track.Firstly,the coupling model of train–bridge systems is reviewed.Then,an ensemble method is presented,which can estimate the small probabilities of a dynamic system with stochastic excitations.The main idea of the ensemble method is to use the NARX(nonlinear autoregressive with exogenous input)model to replace the physical model and apply subset simulation with splitting to obtain the extreme distribution.Finally,the efficiency of the suggested method is compared with the direct Monte Carlo simulation method,and the probability exceedance of train responses under the vertical track irregularity is discussed.The results show that when the small probability of train responses under vertical track irregularity is estimated,the ensemble method can reduce both the calculation time of a single sample and the required number of samples. | Huoyue Xiang Ping Tang Yuan Zhang Yongle Li | 2020 | Railway Engineering Science2020，28，3： | 8 |
| 2 | Material Removal Characteristics of Single-Crystal 4H-SiC Based on Varied-Load Nanoscratch Tests显示文摘Single-crystal silicon carbide(SiC)has been widely applied in the military and civil fields because of its excellent physical and chemical properties.However,as is typical in hard-to-machine materials,the good mechanical properties result in surface defects and subsurface damage during precision or ultraprecision machining.In this study,single-and double-varied-load nanoscratch tests were systematically performed on single-crystal 4H-SiC using a nanoindenter system with a Berkovich indenter.The material removal characteristics and cracks under different planes,indenter directions,normal loading rates,and scratch intervals were analyzed using SEM,FIB,and a 3D profilometer,and the mechanisms of material removal and crack propagation were studied.The results showed that the Si-plane of the single-crystal 4H-SiC and edge forward indenter direction are most suitable for material removal and machining.The normal loading rate had little effect on the scratch depth,but a lower loading rate increased the ductile region and critical depth of transition.Additionally,the crack interaction and fluctuation of the depth-distance curves of the second scratch weakened with an increase in the scratch interval,the status of scratches and chips changed,and the comprehensive effects of the propagation and interaction of the three cracks resulted in material fractures and chip accumulation.The calculated and experimental values of the median crack depth also showed good consistency and relativity.Therefore,this study provides an important reference for the high-efficiency and precision machining of single-crystal SiC to ensure high accuracy and a long service life. | Kun Tang Wangping Ou Cong Mao Jie Liang Moke Zhang Mingjun Zhang Yongle Hu | 2023 | Chinese Journal of Mechanical Engineering2023，36，4： | 1 |
| 3 | Prediction of Grinding Force by an Electroplated Grinding Wheel with Orderly-Micro-Grooves显示文摘The ability to predict a grinding force is important to control,monitor,and optimize the grinding process.Few theoretical models were developed to predict grinding forces when a structured wheel was used in a grinding process.This paper aimed to establish a single-grit cutting force model to predict the ploughing,friction and cutting forces in a grinding process.It took into the consideration of actual topography of the grinding wheel,and a theoretical grinding force model for grinding hardened AISI 52100 by the wheel with orderly-micro-grooves was proposed.The model was innovative in the sense that it represented the random thickness of undeformed chips by a probabilistic expression,and it reflected the microstructure characteristics of the structured wheel explicitly.Note that the microstructure depended on the randomness of the protruding heights and distribution density of the grits over the wheel.The proposed force prediction model was validated by surface grinding experiments,and the results showed(1)a good agreement of the predicted and measured forces and(2)a good agreement of the changes of the grinding forces along with the changes of grinding parameters in the prediction model and experiments.This research proposed a theoretical grinding force model of an electroplated grinding wheel with orderly-micro-grooves which is accurate,reliable and effective in predicting grinding forces. | Cong Mao Jiali Wang Mingjun Zhang Xincheng Wang Yuanqiang Luo Weidong Tang Kun Tang Zhuming Bi Yongle Hu Zhenheng Lin | 2023 | Chinese Journal of Mechanical Engineering2023，36，4： | 0 |
| 4 | Circulating nucleic acids as liquid biopsies for disease prediction,screening and diagnosis显示文摘Liquid biopsy used molecular information in body liquid to perform early diagnosis,screening,monitoring,prognosis,and treatment of various diseases.Circulating free nucleic acids(cfNA)are important diagnostic biomarkers,providing a window to accurately and immediately observe the body's vital activity status.With the development of gene sequencing technology and bioinformatics technology,genetic,epigenetic,and fragtomics alterations that can be detected in cfDNA,as well as the expression level of miRNA and cf-mRNA can be quantified,this can reflect its tissue origin,gene regulation,genome evolution,and disease pathogenesis.This review focuses on the clinical utility of cfNA in different body liquids(blood,urine,bile),and discusses the diagnostic efficacy and accuracy of cfNA as diagnostic biomarkers in a variety of diseases.Blood is widely used to diagnose various tissue lesions for liquid biopsies as a body fluid circulating throughout the body,reflecting the state of the entire body.Bile and urine,as local circulating body fluids,can better reflect the changing state of tissues around the biliary tract and tissues around the bladder,respectively.In addition,normalized sample preservation,cfNA extraction,and detection procedures will help the practical application of cfNA in the clinic. | Yuqing Sun Yongling Tang Long Yu Yuhao Wang Shuang Peng Xiang Zhou | 2023 | Science China Chemistry2023，66，11： | 0 |
| 5 | Spatiotemporal Differences and Classification Regulation of Urbanization Impact on Agricultural Development in Shrinking Areas:A Case Study of 15 Shrinking Cities in Three Provinces of Northeast China显示文摘Studying the impact of urbanization on agricultural development in shrinking areas is important for maintaining food security and promoted agricultural development in China.Based on the measurement results of the shrinking cities in the three provinces of Northeast China,this paper selects 15 shrinking cities as the research object,and constructs a multi-dimensional index system to explore the impact of the urbanization level of the shrinking areas on the agricultural development in the region since 2007–2019,analyzes the influencing factors and their differences by using the geographically-weighted regression model and Geodetector,and proposes a targeted regulation strategy.The results show that:1)overall,there is a negative correlation between the urbanization level and the agricultural development level in the contracted areas of the three northeastern provinces.The urbanization level in these areas has a certain negative impact on the overall level of agricultural development;2)regarding the time dimension,the impact of urbanization level on the agricultural development level in the contracted areas of the three northeastern provinces gradually increases over time;3)regarding the spatial pattern,the overall impact of shrinking urbanization levels in the three provinces of Northeast China on the agricultural development shows a significant distribution pattern of high in the east and low in the west;4)the total population and natural population growth rate at the end of the year were the main factors influencing a certain level of urbanization on agricultural development in the shrinking cities while population density and the urban fixed asset investment rate were the secondary factors;and 5)the main reasons why the level of agricultural development in different cities was affected by the level of urbanization were different.However,they can be categorized into areas of population loss and spatial construction,which can be further divided into area of population loss in the northeast,areas of negative population growth in the west,and areas of urban spatial change in the south.According to the causes of the impact,this paper adopted targeted regulation strategies and formulated relevant policies and solutions that cater to local conditions. | CHEN Xiaohong LIU Haihan AN Yongle DAI Yue PAN Wei WANG Ying TANG We | 2023 | Chinese Geographical Science2023，33，6： | 0 |
| 6 | Method for the extraction of circulating nucleic acids based on MOF reveals cell-free RNA signatures in liver cancer显示文摘Cell-free RNA(cf RNA) allows assessment of health, status, and phenotype of a variety of human organs and is a potential biomarker to non-invasively diagnose numerous diseases. Nevertheless, there is a lack of highly efficient and bias-free cf RNA isolation technologies due to the low abundance and instability of cf RNA.Here, we developed a reproducible and high-efficiency isolation technology for different types of cell-free nucleic acids(containing cf RNA and viral RNA) in serum/plasma based on the inclusion of nucleic acids by metal-organic framework(MOF) materials, which greatly improved the isolation efficiency and was able to preserve RNA integrity compared with the most widely used research kit method. Importantly, the quality of cf RNA extracted by the MOF method is about 10-fold that of the kit method, and the MOF method isolates more than three times as many different RNA types as the kit method. The whole transcriptome mapping characteristics of cf RNA in serum from patients with liver cancer was described and a cf RNA signature with six cf RNAs was identified to diagnose liver cancer with high diagnostic efficiency(area under curve = 0.905 in the independent validation cohort) using this MOF method. Thus, this new MOF isolation technique will advance the field of liquid biopsy, with the potential to diagnose liver cancer. | Yuqing Sun Haixin Yu Shaoqing Han Ruoxi Ran Ying Yang Yongling Tang Yuhao Wang Wenhao Zhang Heng Tang Boqiao Fu Boshi Fu Xiaocheng Weng Song-Mei Liu Hexiang Deng Shuang Peng Xiang Zhou | 2024 | National Science Review2024，11，1： | 0 |
| 7 | Criteria and regulatory considerations for the conditional approval of innovative antitumor drugs in China:from the perspective of clinical reviewers显示文摘1 BACKGROUND Before the State Council of the People’s Republic of China issued the“Opinions on the Reform of the Examination and Approval System of Pharmaceutical and Medical Devices”[1],several problems existed in China’s drug evaluation and approval system.The long approval time and low efficiency of new drug marketing seriously affected the enthusiasm for drug innovation.To this end,the current“Drug Registration Regulation”(DRR)[2]was initiated by the National Medical Products Administration of China and officially implemented on July 1,2020.To encourage clinical value-oriented drug innovation,four expedited drug programs were first proposed,including breakthrough therapy drugs,conditional approval,priority review,and special approval procedures.For drugs listed in the expedited programs,the drug regulatory authorities and professional technical institutions should provide policy and technical support,prioritize the allocation of communication and review resources,and thereafter shorten the review time as much as possible. | Limin Zou Yueli Qi Yongling Jiang Ling Tang Yu Du Boyuan Zhao Yanzhe Sun Meiyi Xiang Jun Ma Zhimin Yang | 2023 | Cancer Communications2023，43，2： | 0 |
| 8 | Dielectric Patch Resonator and Antenna显示文摘This paper presents an overview of dielectric patch(DP)antennas developed in recent years.The employed DP resonator composed of a DP and a bottom substrate is analyzed comprehensively here,enabling the easy realization of a quasi-planar DP antenna.It combines the dual advantages of the conventional microstrip patch(MP)antenna and dielectric resonator(DR)antenna in terms of profile,gain,bandwidth,radiation efficiency,and design freedom.Furthermore,the DP antenna inherits the multi-mode characteristic of the DR antenna,thus it has a large number of high-order modes,including TMmn mode and TEmn mode.The high-order modes are widely applied,for example,by combining with the dominant TM10 mode to expand the bandwidth,or selecting multiple higher-order modes to implement a high-gain antenna.Additionally,the non-radiation high-order modes are also utilized to produce natural radiation null in filtering antenna design.In this paper,the design theories and techniques of DP antenna are introduced and investigated,including calculation and control methods of the resonant mode frequencies,analysis of the radiation mechanism,and applications of the multi-mode characteristic.This overview could provide guidance for the subsequent antenna design,thus effectively avoid time-consuming optimization. | Jianxin Chen Xueying Wang Shichang Tang Yongle Wu | 2023 | China Communications2023，20，8： | 0 |
| 9 | Experimental Research on Thermal Performance of Ultra-Thin Flattened Heat Pipes显示文摘Ultra-thin flattened heat pipe(UTHP) is an effective solution to solve the problem of high-power density heat dissipation in narrow space. The key factors that determine its thermal performance include: the shapes and sizes of the UTHP, the wick structure, the type of working fluid and its filling ratio. The change in the filling ratio means not only a change in the amount of the working fluid, but also a change in the space distribution of the gas and liquid phases inside the heat pipe. Therefore, it is important to explore the effect of liquid filling ratio on the thermal performance of UTHP. It can provide effective guidance for the production of UTHP. In this work, experiments were conducted on four groups of UTHPs with different mesh wicks under a series of liquid filling ratios. The results demonstrate that the volume of the filling working fluid should account for 22%-37% of the total internal volume of the UTHP to avoid deterioration of heat transfer during the operation of the UTHP. In addition, a prediction model of the evaporator temperature has been established to provide guidance for the application of UTHPs. | TANG Yongle CAO Jianguang WANG Shuangfeng | 2022 | Journal of Thermal Science2022，31，6： | 0 |
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