中国企业数字化进程的典型事实——来自中国企业创新创业调查的证据

企业数字化转型是数字技术与实体经济相结合的主要方式,也是实现产业升级和培育新质生产力的明确要求。但是,目前学术界仍然缺乏对于广泛中小企业数字化转型发展水平的定量评估。本文利用北京大学企业大数据研究中心开展的中国企业创新创业调查获得的一手数据,定量描述了中国企业互联网使用、数字化管理、线上业务分工、数字化机器四项数字技术的采用情况,并使用欧美国家相似调研数据进行国际比较,进而总结当前中国企业数字化转型的典型事实。本文具有如下发现:第一,中国企业在经营活动中已经普遍采用了数字技术,但数字化进程仍然具有区域、行业差异;第二,中国企业的互联网使用和数字化管理的采用仍然落后于欧美国家,但电子商务和短视频媒体的采用处于领先地位;第三,规模越大、年龄越小、员工工资越高的企业开展数字化转型的概率越高;第四,中老年企业家由于缺乏数字技术相关知识而更难开展数字化转型。本文为中国在新发展阶段进一步加快产业数字化转型升级,特别是中小企业数字化赋能等专项行动,提供了有益的政策参考。

OFDMA-Based Unsourced Random Access in LEO Satellite Internet of Things

This paper investigates the low earth orbit(LEO)satellite-enabled coded compressed sensing(CCS)unsourced random access(URA)in orthogonal frequency division multiple access(OFDMA)framework,where a massive uniform planar array(UPA)is equipped on the satellite.In LEO satellite communications,unavoidable timing and frequency offsets cause phase shifts in the transmitted signals,substantially diminishing the decoding performance of current terrestrial CCS URA receiver.To cope with this issue,we expand the inner codebook with predefined timing and frequency offsets and formulate the inner decoding as a tractable compressed sensing(CS)problem.Additionally,we leverage the inherent sparsity of the UPA-equipped LEO satellite angular domain channels,thereby enabling the outer decoder to support more active devices.Furthermore,the outputs of the outer decoder are used to reduce the search space of the inner decoder,which cuts down the computational complexity and accelerates the convergence of the inner decoding.Simulation results verify the effectiveness of the proposed scheme.

Research Progress of Environment Friendly Plasticizers for Cellulose Acetate Processing

Cellulose acetate(CA)is an important cellulose derivative that can undergo thermoplas-tic processing.Plasticizers can form stable hydrogen bonds with CA molecular chains,reducing intermolecular and intramolecular interactions,and play an important role in the melting processing of CA.In recent years,environmentally friendly plasticizers that are natural,non-toxic,odorless,low dissolution,and low migration have received increas-ing attention in plastic processing.This article reviews the research progress of environ-mentally friendly plasticizers such as natural plasticizers,ionic liquid plasticizers,citrate plasticizers,and polyethylene glycol plasticizers in the processing of cellulose acetate,and looks forward to the application prospects of environmentally friendly plasticizers.

Experimental investigation on divertor tungsten sputtering with neon seeding in ELMy H-mode plasma in EAST tokamak

Neon(Ne)seeding is used to cool the edge plasma by radiation to protect the divertor tungsten(W)target in the Experimental Advanced Superconducting Tokamak(EAST).The W sputtering in the outer divertor target with Ne seeding is assessed by the divertor visible spectroscopy system.It is observed that the W sputtering flux initially increases with Ne concentration in the divertor despite the decreasing plasma temperature.After reaching a maximum around 25 eV,the W sputtering rate starts to decrease,presenting a suppression effect.The effect on the divertor W sputtering flux and yield due to the competition between the increase of the Ne concentration and the decrease of the plasma temperature is discussed.The results show that enough Ne seeding is essential to effectively reduce the electron temperature and thus to suppress W sputtering.Moreover,ELM suppression is observed when Ne and W impurities enter the core plasma,which could be correlated to the enhanced turbulence transport in the pedestal.

Blob properties in I-mode and ELM-free H-mode compared to L-mode on EAST

The blob properties in I-mode and ELM-free H-mode plasmas compared to L-mode have been investigated on the EAST tokamak,including the blob detection rate Nb,sizeδb,lifetimeτb and radial velocity vr,b.The blob properties in L-mode and I-mode are similar,and those in ELM-free H-mode are different to them.The blob Nbis smaller whileτbis larger in H-mode.The experimental blob sizeδband velocity scalings vr,b-δb show a good agreement with the theoretical models.The variation in blob properties during the L-I and H-L transitions,and their relations to the scrape-off layer(SOL)density,edge and SOL turbulence,and SOL collisionality are discussed.The suppression of the edge(inside the last closed flux surface)turbulence is not reflected in the blob behavior,while the blob detection rate shows a correlation with the SOL density and its low-frequency(3–50 kH z)fluctuations.In addition,the blob detection rate is found to increase with the divertor collisionalityΛdiv,indicating a dependence of blob behavior onΛdiv.The differences in blob detection rates among the three operating regimes might be due to their different SOL densities and collisionalities.The investigation contributes to understanding the influences of edge and SOL plasma parameters on the blob behavior.

Runaway electron dynamics in Experimental Advanced Superconducting Tokamak helium plasmas

The generation of runaway electrons(REs)is observed during the low-density helium ohmic plasma discharge in the Experimental Advanced Superconducting Tokamak(EAST).The growth rate of hard x-ray(HXR)is inversely proportional to the line-average density.Besides,the RE generation in helium plasma is higher than that in deuterium plasma at the same density,which is obtained by comparing the growth rate of HXR with the same discharge conditions.The potential reason is the higher electron temperature of helium plasma in the same current and electron density plateau.Furthermore,two Alfvén eigenmodes driven by REs have been observed.The frequency evolution of the mode is not fully satisfied with the Alfvén scaling and when extension of the Alfvén frequency is towards 0,the high frequency branch is~50 kHz.The different spatial position of the two modes and the evolution of the helium concentration could be used to understand deviation between theoretical and experimental observation.

Realization of T_(e0)>10 keV long pulse operation over 100 s on EAST

In 2021,EAST realized a steady-state long pulse with a duration over 100 s and a core electron temperature over 10 keV.This is an integrated operation that resolves several key issues,including active control of wall conditioning,long-lasting fully noninductive current and divertor heat/particle flux.The fully noninductive current is driven by pure radio frequency(RF)waves with a lower hybrid current drive power of 2.5 MW and electron cyclotron resonance heating of 1.4 MW.This is an excellent experimental platform on the timescale of hundreds of seconds for studying multiscale instabilities,electron-dominant transport and particle recycling(plasma-wall interactions)under weak collisionality.

基于集成学习算法构建有机化学品鱼体生物富集因子的QSAR预测模型

生物富集因子(BCF)是评价化学品生物累积能力的重要参数。目前全球市场上使用的化学品数量已超过了35万种,但是只有一千多种化学品具有BCF值。定量构效关系(QSAR)模型被认为是一种有效填补数据空缺的方法。目前大多数预测BCF的QSAR模型为单一模型,而集成模型可能会对BCF的预测效果有所改进。本研究建立了一个全面的鱼类BCF数据库,涵盖1300多种有机化学品的BCF实测值。基于此数据库,依据QSAR模型构建和验证导则,使用多种机器学习算法建立了预测鱼类BCF的5种单一模型和11种集成模型。结果表明,与单一模型相比,集成模型具有更好的拟合能力、稳健性、预测准确性以及更广泛的应用域。进一步使用最优集成模型对《中国现有化学物质清单》(IECSC)中化学物质的BCF进行了预测,结果表明该清单中有1066种化学物质具有生物累积性,86种化学物质具有强生物累积性。本研究所构建的模型可为化学品生物累积能力评估提供必要数据,支持化学品风险评价与管理工作。

Breast cancer screening and early diagnosis in Chinese women

Breast cancer is the most common malignant tumor in Chinese women,and its incidence is increasing.Regular screening is an effective method for early tumor detection and improving patient prognosis.In this review,we analyze the epidemiological changes and risk factors associated with breast cancer in China and describe the establishment of a screening strategy suitable for Chinese women.Chinese patients with breast cancer tend to be younger than Western patients and to have denser breasts.Therefore,the age of initial screening in Chinese women should be earlier,and the importance of screening with a combination of ultrasound and mammography is stressed.Moreover,Chinese patients with breast cancers have several ancestry-specific genetic features,and aiding in the determination of genetic screening strategies for identifying high-risk populations.On the basis of current studies,we summarize the development of risk-stratified breast cancer screening guidelines for Chinese women and describe the significant improvement in the prognosis of patients with breast cancer in China.

Recent advances in quantum dots-based biosensors for antibiotics detection

Antibiotics are a category of chemical compounds used to treat bacterial infections and are widely applied in cultivation,animal husbandry,aquaculture,and pharmacy.Currently,residual antibiotics and their metabolites pose a potential risk of allergic reactions,bacterial resistance,and increased cancer incidence.Residual antibiotics and the resulting bacterial antibiotic resistance have been recognized as a global challenge that has attracted increasing attention.Therefore,monitoring antibiotics is a critical way to limit the ecological risks from antibiotic pollution.Accordingly,it is desirable to devise new analytical platforms to achieve efficient antibiotic detection with excellent sensitivity and specificity.Quantum dots(QDs)are regarded as an ideal material for use in the development of antibiotic detection biosensors.In this review,we characterize different types of QDs,such as silicon,chalcogenide,carbon,and other doped QDs,and summarize the trends in QD-based antibiotic detection.QD-based sensing applications are classified according to their recognition strategies,including molecularly imprinted polymers(MIPs),aptamers,and immunosensors.We discuss the advantages of QD-derived antibiotic sensors,including low cost,good sensitivity,excellent stability,and fast response,and illustrate the current challenges in this field.

Synergistic effects of 4-nitrophenol degradation using gamma irradiation combined with a advanced oxidation process

The radiation-induced degradation of 4-nitrophenol(4-NP) was performed in combination with a Fenton reagent, H_2O_2, and Ti O_2 nanoparticles to investigate the synergetic effects of radiolytical degradation combined with other advanced oxidation processes. The experimental results indicated that the degradation efficiency of 4-NP was 87.5, 57.4, and 41.0 % at a dose of 20 k Gy when its initial concentration was 100, 200, and 350 mg/L, respectively. Radiation combined with H_2O_2, the Fenton method,and Ti O_2 remarkably increased the degradation efficiency of 4-NP, showing the synergetic effects. Radiation may enhance the biodegradability of 4-NP, suggesting that it has the potential to be used as a pretreatment method in combination with the biological method for the treatment of industrial wastewater containing toxic organic pollutants. Major intermediates during the 4-NP degradation process were identified and a possible degradation pathway was tentatively proposed.

Study on plasma cleaning of the large-scale first mirror of the charge exchange recombination spectroscopy diagnostic on EAST

In the Experimental Advanced Superconducting Tokamak(EAST),the reflectivity of the charge exchange recombination spectroscopy(CXRS)first mirror(FM)was dramatically dropped down to 20%of the original value after the operation of two EAST experimental campaigns from 2014-2015,leading to degradation of the signal intensity of the CXRS diagnostic to an unacceptably low level.The radio frequency(RF)plasma cleaning of the CXRS FM with a dimension of 303×81×76 mm3 and a small curvature of 0.008 mm-1 was performed to remove deposits to recover the reflectivity.After 168 h cleaning by RF plasma,the maximum specular reflectivity of the FM could reach 92%of the original value at 532 nm,making the cleaned CXRS FM eligible to be reused for the CXRS diagnostic in the 2016 EAST campaign.Dedicated tests of sputtering polished mirror samples were performed to explore the cleaning uniformity and possible damage to the mirror surface.The specular reflectivity did not show obvious dependence on locations along the surface with the same cleaning time.The measured surface roughness gradually increased with sputtering time.The reflectivity remained almost unchanged regardless of different sputtering times and locations,indicating negligible damage to the FM surface even after 100 h sputtering.The recontaminated CXRS FM in the 2016 EAST campaign was firstly cleaned for 81 h,and the least reflectivity recovery for areas with relatively thick deposits was only 40%.After continuing cleaning to 147 h,redeposition of the sputtered residual deposits on the FM surface was observed.In the future for in situ cleaning of the FMs in EAST and ITER,deposits should be removed timely when they are very thin taking into account a very long cleaning time and presumable redeposition of thick and nonuniform deposits.

Divertor detachment operation in helium plasmas with ITER-like tungsten divertor in EAST

Detachment in helium(He)discharges has been achieved in the EAST superconducting tokamak equipped with an ITER-like tungsten divertor.This paper presents the experimental observations of divertor detachment achieved by increasing the plasma density in He discharges.During density ramp-up,the particle flux shows a clear rollover,while the electron temperature around the outer strike point is decreasing simultaneously.The divertor detachment also exhibits a significant difference from that observed in comparable deuterium(D)discharges.The density threshold of detachment in the He plasma is higher than that in the D plasma for the same heating power,and increases with the heating power.Moreover,detachment assisted with neon(Ne)seeding was also performed in L-and H-mode plasmas,pointing to the direction for reducing the density threshold of detachment in He operation.However,excessive Ne seeding causes confinement degradation during the divertor detachment phase.The precise feedback control of impurity seeding will be performed in EAST to improve the compatibility of core plasma performance with divertor detachment for future high heating power operations.

Characterization of dust collected in EAST after 2019 campaign

Dust presented in experimental advanced superconducting tokamak(EAST)with mixed plasmafacing materials has been collected and characterized for the first time.Dust at different positions in the vessel was collected by vacuum cleaner after the first experimental campaign in 2019.The shape,composition,and size of dust particles have been analyzed using different methods.About 80%of the total number of dust particles have size between 20 and 80μm,and most of dust particles are spherical,while schistose shape,columnar and irregular shape were also found.With the help of energy-dispersive x-ray spectroscopy different elements of dust have been identified,which is generally consistent with the different plasma-facing components in EAST.Both x-ray fluorescence and inductively coupled plasma emission spectrometer are complementary methods for measuring the dust composition quantitatively.It was found that the major components of dust were lithium dust in the form of lithium carbonate and lithium hydroxide,which is due to the routine lithium wall conditioning during EAST operation.

Simulated Annealing for the 0/1 Multidimensional Knapsack Problem

In this paper a simulated annealing(SA)algorithm is presented for the 0/1 mul- tidimensional knapsack problem.Problem-specific knowledge is incorporated in the algorithm description and evaluation of parameters in order to look into the perfor- mance of finite-time implementations of SA.Computational results show that SA per- forms much better than a genetic algorithm in terms of solution time,whilst having a modest loss of solution quality.

Pattern of liver injury in adult patients with COVID-19: a retrospective analysis of 105 patients

Background: Recent studies reported that patients with coronavirus disease-2019(COVID-19) might have liver injury. However, few data on the combined analysis and change patterns of alanine aminotransferase(ALT), aspartate aminotransferase(AST) and total bilirubin(TBil) have been shown.Methods: This is a single-center retrospective study. A total of 105 adult patients hospitalized for confirmed COVID-19 in Beijing Ditan Hospital between January 12, and March 17, 2020 were included, and divided into mild group(n=79) and severe group(n=26). We compared liver functional test results between the two groups. Category of ALT change during the disease course was also examined.Results: 56.2%(59/105) of the patients had unnormal ALT, AST, or total TBil throughout the course of the disease, but in 91.4%(96/105) cases the level of ALT, AST or TBil ≤3 fold of the upper limit of normal reference range(ULN). The overall distribution of ALT, AST, and TBil were all significantly difference between mild and severe group(P<0.05). The percentage of the patients with elevated both ALT and AST was 12.7%(10/79) in mild cases vs. 46.2%(12/26) in severe cases(P=0.001). 34.6%(9/26) severe group patients started to have abnormal ALT after admission, and 73.3%(77/105) of all patients had normal ALT before discharge.Conclusions: Elevated liver function index is very common in patients with COVID-19 infection, and the level were less than 3×ULN, but most are reversible. The abnormality of 2 or more indexes is low in the patients with COVID-19, but it is more likely to occur in the severe group.

A Curriculum Cluster Teaching Model of Software Engineering from the Metaverse Perspective

To solve the teaching difficulties,including hard cultivating engineering thinking,a reasonable transition of professional training,and deep cooperation of students,which impeded the cultivation effectiveness of students’ability to solve complex engineering problems,the paper proposed a Zongheng group teaching model of curriculum cluster based on projects.Firstly,from the perspective of Metaverse,and considering the professional,current teaching situation and learning situation,we analyzed the professional background and proposed the Zongheng group teaching model of curriculum cluster.Then,the connotation,teaching construction and implementation details are explained.After that,we summarized the teaching effect about the 2 years of exploration and practice in the major of software engineering at College of Computer and Information Technology in Mudanjiang Normal University,to clarify the effect of teaching reform.2 years of teaching practice shows that making full use of the advantages of curriculum cluster,Zongheng group and the project-based teaching method,the long-range training,in-depth student cooperation,and the students’ability of solving complex engineering problems are improved.

The Feasibility Research on Distribution Network Closed Loop Based on the Load Transfer Model

With the continuous development of urban distribution network, most of the distribution network has formed a dual power supply mode. The traditional way of distribution network load operating mainly adopts the power method, while satisfied the requirements of the safety of power grid, but will cause external short time power outages, poor user experience, realizing the distribution network outage rearrangement of load is a necessary means to improve power supply reliability. This paper presents mathematical model of load transfer in distribution network. The differences of voltage of amplitude and phase angle on both sides are calculated by the power flow. According to the differential pressure to determine whether the loop can be closed at the loop operation, thereby improving the success rate of operation.

Zhang Zhongjing's medication rules for treating constipation based on data analysis

Objective:To explore the characteristics of ZHANG Zhongjing's medication for constipation by analyzing the prescriptions of treatise on Shanghan Lun and Jingui Yaolue.Methods:the formulations that met the inclusion criteria were selected to establish a database,and the regularity of ZHANG Zhongjing's medication for constipation was analyzed by the methods of frequency,association rules and clustering.Results:In this study,11 prescriptions and 24 medicines were included.High-frequency use of drugs rhubarb,licorice,CortexMagnoliae Officinalis,fructus aurantii immaturus,mirabilis,ginger,jujube,white atractylodes rhizome,cassia twig,Chinese herbaceous peony.A total of 17 association rules(11 rules for 2 drugs and 6 rules for 3 drugs)were obtained by mining,including"Rhubarb+Mirabilite","fructus aurantii immaturus+Cortex Magnoliae Officinalis","Rhubarb+Cortex Magnoliae Officinalis","Rhubarb+Cortex Magnoliae Officinalis+fructus aurantii immaturus",and so on,and 7 groups of drug pair association group and 2 groups of multi-flavor drug association group were obtained.Network link analysis shows that there are 7 groups of strong link compatibility.Medium link compatibility 46 groups.Cluster analysis obtained 14 groups,including 8 single-taste drug groups,3 drug-pair polymerization groups and 3 multi-taste drug polymerization groups.Conclusions:ZHANG Zhongjing is not only good at using purgative medicine in treating constipation treating constipation,but also pays attention to invigorating qi and activating blood circulation,resolving the surface and regulating dampness,soothing the liver and regulating qi.

A Sewage Sludge Derived Composite Material for Adsorption of Antibiotics – Kinetics

A novel sewage-sludge derived composite material was developed for the adsorptive removal of organic pollutants from water. In this study a batch adsorption study was carried out to examine the kinetics of antibiotics adsorption by this composite material. A pseudo-second order kinetics model fits the data extremely well, suggesting that chemical adsorption, rather than physical adsorption, is likely the main mechanism of the separation process.