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Dynamic simulation of a space gas-cooled reactor power system with a closed Brayton cycle

《能源前沿(英文)》 2021年 第15卷 第4期   页码 916-929 doi: 10.1007/s11708-021-0757-9

摘要: Space nuclear reactor power (SNRP) using a gas-cooled reactor (GCR) and a closed Brayton cycle (CBC) is the ideal choice for future high-power space missions. To investigate the safety characteristics and develop the control strategies for gas-cooled SNRP, transient models for GCR, energy conversion unit, pipes, heat exchangers, pump and heat pipe radiator are established and a system analysis code is developed in this paper. Then, analyses of several operation conditions are performed using this code. In full-power steady-state operation, the core hot spot of 1293 K occurs near the upper part of the core. If 0.4 $ reactivity is introduced into the core, the maximum temperature that the fuel can reach is 2059 K, which is 914 K lower than the fuel melting point. The system finally has the ability to achieve a new steady-state with a higher reactor power. When the GCR is shut down in an emergency, the residual heat of the reactor can be removed through the conduction of the core and radiation heat transfer. The results indicate that the designed GCR is inherently safe owing to its negative reactivity feedback and passive decay heat removal. This paper may provide valuable references for safety design and analysis of the gas-cooled SNRP coupled with CBC.

关键词: gas-cooled space nuclear reactor power     closed Brayton cycle     system startup and shutdown     positive reactivity insertion accident    

Parameter for judging reactivity of coal and coke

HE Hongzhou, LUO Zhongyang, CEN Kefa

《能源前沿(英文)》 2008年 第2卷 第3期   页码 354-358 doi: 10.1007/s11708-008-0052-z

摘要: To eliminate the judgment error of char reactivity arising from different carbon content of samples, a new parameter called specific maximum weight loss rate was introduced. It is defined as the quotient of the maximum weight loss rate in non-isothermal thermogravimetric analysis (TGA) experiment to the carbon content of the corresponding sample. The reactivity of different kinds of coal, the reactivity of the same coal type with different lithotype, and the reactivity of the char with different carbon conversion rates were checked by using the specific maximum weight loss rate, and the results were analyzed and compared with those obtained by using other criteria. The results show that the specific maximum weight loss rate can be used as a commonality parameter to evaluate and distinguish the reactivity of different coal and char. The heating rate selected in TGA experiment has no effect on the judgment.

关键词: thermogravimetric analysis     specific maximum     different lithotype     experiment     TGA experiment    

A job-insertion heuristic for minimizing the mean flowtime in dynamic flowshops

Guang GUO, Bo WU, Shuzi YANG

《机械工程前沿(英文)》 2011年 第6卷 第2期   页码 197-202 doi: 10.1007/s11465-011-0211-5

摘要:

A new adaptive job-insertion based heuristic is presented to minimize the mean flowtime in a dynamic flowshop consisting of machines. Job orders arrive to the system randomly, and the job arrival or release dates are not known in advance. The heuristic is derived by inserting new jobs into the scheduled sequence as needed when the machine becomes free. Computation results indicate that the proposed heuristic performs 2.7%–10.8% better than the SPT dispatching rule, which is currently one of the most effective methods for minimizing the mean flowtime in dynamic flowshops.

关键词: scheduling     dynamic flowshops     flowtime     heuristic     mean flowtime    

Effects of different types of biochar on the properties and reactivity of nano zero-valent iron in soil

《环境科学与工程前沿(英文)》 2021年 第15卷 第5期 doi: 10.1007/s11783-021-1388-4

摘要:

• Biochar enhanced the mobility and stability of zero-valent iron nanoparticles.

关键词: Nano zero-valent iron     Biochar     BDE209     Transport     Soil    

Triage for management of cervical high-grade squamous intraepithelial lesion patients with positive margin

null

《医学前沿(英文)》 2017年 第11卷 第2期   页码 223-228 doi: 10.1007/s11684-017-0517-8

摘要:

The objective of this study is to guide a triage for the management of cervical high-grade squamous intraepithelial lesion (HSIL) patients with positive margin by conization. Clinico-pathological data of HSIL patients with positive margin by conization were retrospectively collected from January 2009 to December 2014. All patients underwent secondary conization or hysterectomy within 6 months. The rate of residual lesion was calculated, and the factors associated with residual lesion were analyzed by univariate and multivariate analyses. Among a total of 119 patients, 56 (47.06%) patients presented residual HSIL in their subsequent surgical specimens, including 4 cases of invasive cervical carcinoma (3 stage IA1 and 1 stage IA2 patients). Univariate analysis showed that patient age>35 years (P=0.005), menopausal period>5 years (P=0.0035), and multiple-quadrant involvement (P=0.001) were significantly correlated with residual disease; however, multivariate analysis revealed that multiple-quadrant involvement (P=0.001; OR, 3.701; 95%CI, 1.496–9.154) was an independent risk factor for residual disease. Nearly half of HSIL patients with positive margin by conization were disease-free in subsequent surgical specimens, and those with multiple positive margins may consider re-conization or re-assessment.

关键词: cervical high-grade squamous intraepithelial lesion     conization     positive surgical margin     hysterectomy    

NO conversion by positive streamer discharge—effects of gas compositions and reaction conditions

HE Wei, ZHU Tianle, LI Jing

《环境科学与工程前沿(英文)》 2007年 第1卷 第2期   页码 153-158 doi: 10.1007/s11783-007-0027-z

摘要: The effects of gas compositions and reaction conditions on NO conversion by positive streamer discharge were experimentally investigated by using a link tooth wheel-cylinder reactor. The results showed that NO conversion increased w

关键词: conversion     streamer discharge     wheel-cylinder     positive streamer    

Genetic Study Identifies CBLN4 as a Novel Susceptibility Gene for Accident Proneness

Shu-lin Zhang,Hui-qing Jin,Yang Song,Wan-sheng Yu,Liang-dan Sun

《工程管理前沿(英文)》 2016年 第3卷 第1期   页码 30-38 doi: 10.15302/J-FEM-2016008

摘要: Frequent traffic accidents constitute a major danger to human beings. The accident-prone driver who has the stable physiological, psychological, and behavioral characteristics is one of the most prominent causes of traffic accidents. The internal link between the individual characteristics and the accident proneness has been a difficult point in the accident prevention research. The authors selected accident-prone drivers as cases and safe drivers as controls (case-control group) from 18,360 drivers who were enrolled from three public transportation incorporations of China using area stratified sampling method. The case-control groups were 1:1 matched. The authors performed genome-wide association study (GWAS) by 179 cases and 179 controls using the U.S. Affymetrix Genome-Wide Human Mapping SNP 6.0 Array. The authors observed that the gene frequencies of 34 single-nucleotide polymorphisms (SNPs) in three regions of cases were higher than those in the control ( <10 ). The authors then tested two independent replication sets for strong association 6 SNPs in 349 pairs of case-control drivers using the U.S. ABI 3730 sequencing method. The results indicated that SNP rs6069499 within linked CBLN4 gene are strongly associated with accident proneness ( =6.37×10 ). According to CBLN4 gene mainly involved in adrenal development and the regulation of secretion, the authors performed 12 biochemical parameters of the blood using radioimmunoassay. The levels of dopamine (DA) and adrenocorticotropic (ACTH) hormone showed significant differences between accident-prone drivers and safe drivers ( =0.03, =0.01). It is suggested that the accident-prone drivers may have the idiosyncrasy of susceptibility.

关键词: accident proneness     genome-wide association study (GWAS)     dopamine (DA)     ACTH     susceptibility gene     traffic accident epidemiology     accident prevention     traffic safety     three-dimensional model    

把握生物经济时代精神,实践进步的幸福观

甘自恒

《中国工程科学》 2007年 第9卷 第2期   页码 5-11

摘要:

据预测,2020年,全球将进入以生物技术产业为主导产业的生物经济时代;阐述了生物经济的提出、 分类、特征和定义;主张把握生物经济时代精神,实践进步的幸福观;探讨了为什么要强调谋求人民幸福,什 么是进步的幸福观,应提倡那些进步的幸福观,以及我国科技界应该怎样实践进步的幸福观。

关键词: 生物经济     幸福     进步的幸福观    

Nanostructure and reactivity of soot from biofuel 2,5-dimethylfuran pyrolysis with CO

Lijie ZHANG, Kaixuan YANG, Rui ZHAO, Mingfei CHEN, Yaoyao YING, Dong LIU

《能源前沿(英文)》 2022年 第16卷 第2期   页码 292-306 doi: 10.1007/s11708-020-0658-3

摘要: This paper investigated the nanostructure and oxidation reactivity of soot generated from biofuel 2,5-dimethylfuran pyrolysis with different CO additions and different temperatures in a quartz tube flow reactor. The morphology and nanostructure of soot samples were characterized by a low and a high resolution transmission electron spectroscopy (TEM and HRTEM) and an X-ray diffraction (XRD). The oxidation reactivity of these samples was explored by a thermogravimetric analyzer (TGA). Different soot samples were collected in the tail of the tube. With the increase of temperature, the soot showed a smaller mean particle diameter, a longer fringe length, and a lower fringe tortuosity, as well as a higher degree of graphization. However, the variation of soot nanostructures resulting from different CO additions was not linear. Compared with 0%, 50%, and 100% CO additions at one fixed temperature, the soot collected from the 10% CO addition has the highest degree of graphization and crystallization. At three temperatures of 1173 K, 1223 K, and 1273 K, the mean values of fringe length distribution displayed a ranking of 10% CO >100% CO >50% CO while the mean particle diameters showed the same order. Furthermore, the oxidation reactivity of different soot samples decreased in the ranking of 50% CO addition>100% CO addition>10% CO addition, which was equal to the ranking of mean values of fringe tortuosity distribution. The result further confirmed the close relationship between soot nanostructure and oxidation reactivity.

关键词: 2     5-dimethylfuran pyrolysis     soot     CO2 addition     nanostructure     reactivity    

基于本质安全的工业事故风险管理方法研究

吴宗之

《中国工程科学》 2007年 第9卷 第5期   页码 46-49

摘要:

从风险管理角度对生产过程中的安全防护方法进行了分类和论述,提出了基于本质安全思想的工业 事故综合风险管理方法与程序,其核心内容是在常规的危险辨识和风险评价基础上,优先应用本质安全原理来 减少、消除危险,综合采用无源安全措施、有源安全措施或多层安全防护措施与功能安全标准,将风险降低至 可接受水平;提出了本质安全应与清洁生产、绿色化学、循环经济同等纳入优先发展的技术和政策等建议。

关键词: 本质安全     风险管理     事故预防     安全设计    

Prognostic value of the 21-gene recurrence score in ER-positive, HER2-negative, node-positive breast

Jiayi Wu, Weiqi Gao, Xiaosong Chen, Chunxiao Fei, Lin Lin, Weiguo Chen, Ou Huang, Siji Zhu, Jianrong He, Yafen Li, Li Zhu, Kunwei Shen

《医学前沿(英文)》 2021年 第15卷 第4期   页码 621-628 doi: 10.1007/s11684-020-0738-0

摘要: Multi-gene assays have emerged as crucial tools for risk stratification in early-stage breast cancer. This study aimed to evaluate the prognostic significance of the 21-gene recurrence score (RS) in Chinese patients with pN0-1, estrogen receptor-positive (ER ), human epidermal growth factor receptor 2-negative (HER2 ) breast cancer. Among 800 patients recruited between 2009 and 2016, the median RS was 24 (0–69), with 27.4%, 46.8%, and 25.9% patients classified into low-, intermediate-, and high-risk groups. Cox regression analysis demonstrated that the high-risk category was associated with significantly higher odds of invasive disease-free survival (IDFS) and distant disease-free survival (DDFS) events compared with the low-risk category (IDFS: HR= 2.450, 95% CI 1.017–5.902, = 0.046; DDFS: HR= 2.829, 95% CI 1.013–7.901, = 0.047). No significant association between RS category and overall survival (OS) was found (intermediate vs. low: HR= 1.244, 95% CI 0.292–5.297, = 0.768; high vs. low: HR= 2.933, 95% CI 0.759–11.327, = 0.119). RS, as a continuous variable, was a highly significant predictor for IDFS (HR= 1.028, 95% CI 1.010–1.047, = 0.002), DDFS (HR= 1.030, 95% CI 1.010–1.051, = 0.003), and OS (HR= 1.034, 95% CI 1.007–1.063, = 0.014). Our findings suggested that RS may predict IDFS in Chinese patients with ER /HER2 breast cancer with N0 or N1 disease.

关键词: early breast cancer     21-gene assay     recurrence score     prognosis    

Total phosphorus accident pollution and emergency response study based on geographic information system

Aifeng Zhai, Xiaowen Ding, Lin Liu, Quan Zhu, Guohe Huang

《环境科学与工程前沿(英文)》 2020年 第14卷 第3期 doi: 10.1007/s11783-020-1223-3

摘要: A new algorithm of two-dimensional water quantity and the quality model was built. The migration and diffusion of TP was simulated. The emergency measures for sudden water pollution accidents was proposed. In recent years, sudden water pollution accidents in China’s rivers have become more frequent, resulting in considerable effects on environmental safety. Therefore, it is necessary to simulate and predict pollution accidents. Simulation and prediction provide strong support for emergency disposal and disaster reduction. This paper describes a new two-dimensional water quantity and the quality model that incorporates a digital elevation model into the geographic information system. The model is used to simulate sudden water pollution accidents in the main stream of the Yangtze River and Jialing River in the Chongqing section of the Three Gorges Reservoir area. The sectional velocity distribution and concentration change of total phosphorus are then analyzed under four hydrological situations. The results show that the proposed model accurately simulates and predicts the concentration change and migration process of total phosphorus under sudden water pollution accidents. The speed of migration and diffusion of pollutants is found to be greatest in the flood season, followed by the water storage period, drawdown season, and dry season, in that order. The selection of an appropriate water scheduling scheme can reduce the peak concentration of river pollutants. This study enables the impact of pollutants on the ecological environment of river water to be alleviated, and provides a scientific basis for the emergency response to sudden water pollution accidents in the Three Gorges Reservoir area.

关键词: Sudden water pollution accident     Total phosphorus     Predictive model     Contaminant simulation     Water scheduling     Measure    

安全理论基本假说

于海湧,李芳

《中国工程科学》 2006年 第8卷 第10期   页码 85-88

摘要:

通过大量事故案例及对现有安全理论的分析,将所有事故分为3类:自然事故、随机事故和人为事故,根据这3种事故的特点采用数学方程进行描述、量化,从数学模型角度论述事故发生的必然性、随机性和可预防性,以及不安全的绝对性和安全的相对性的辩证关系。同时根据数学模型提出了完整的、科学的事故预防基本对策。

关键词: 安全理论     事故类型     数学方程     事故预防    

“7·23”旅客列车事故的重要启示

孙永福

《中国工程科学》 2012年 第14卷 第12期   页码 4-9

摘要:

阐述了“7·23”旅客列车事故发生经过并进行了原因分析,从工程管理视角研究提出了4点重要启示:强化铁路新产品研发管理,完善铁路新产品准入管理,提高铁路运输应急处置能力和科学有序地推动铁路建设。

关键词: 旅客列车事故     研发管理     准入管理     应急处置     铁路建设管理    

Effect of pressure on gasification reactivity of three Chinese coals with different ranks

Chunyu LI, Jiantao ZHAO, Yitian FANG, Yang WANG

《化学科学与工程前沿(英文)》 2010年 第4卷 第4期   页码 385-393 doi: 10.1007/s11705-010-0501-1

摘要: The gasification reactivities of three kinds of different coal ranks (Huolinhe lignite, Shenmu bituminous coal, and Jincheng anthracite) with CO and H O was carried out on a self-made pressurized fixed-bed reactor at increased pressures (up to 1.0 MPa). The physicochemical characteristics of the chars at various levels of carbon conversion were studied via scanning electron microscopy (SEM), X-ray diffraction (XRD), and BET surface area. Results show that the char gasification reactivity increases with increasing partial pressure. The gasification reaction is controlled by pore diffusion, the rate decreases with increasing total system pressure, and under chemical kinetic control there is no pressure dependence. In general, gasification rates decrease for coals of progressively higher rank. The experimental results could be well described by the shrinking core model for three chars during steam and CO gasification. The values of reaction order with steam were 0.49, 0.46, 0.43, respectively. Meanwhile, the values of reaction order with CO were 0.31, 0.28, 0.26, respectively. With the coal rank increasing, the pressure order is higher, the activation energies increase slightly with steam, and the activation energy with CO increases noticeably. As the carbon conversion increases, the degree of graphitization is enhanced. The surface area of the gasified char increases rapidly with the progress of gasification and peaks at about 40% of char gasification.

关键词: coal     gasification     pressure     reaction order     shrinking core model    

标题 作者 时间 类型 操作

Dynamic simulation of a space gas-cooled reactor power system with a closed Brayton cycle

期刊论文

Parameter for judging reactivity of coal and coke

HE Hongzhou, LUO Zhongyang, CEN Kefa

期刊论文

A job-insertion heuristic for minimizing the mean flowtime in dynamic flowshops

Guang GUO, Bo WU, Shuzi YANG

期刊论文

Effects of different types of biochar on the properties and reactivity of nano zero-valent iron in soil

期刊论文

Triage for management of cervical high-grade squamous intraepithelial lesion patients with positive margin

null

期刊论文

NO conversion by positive streamer discharge—effects of gas compositions and reaction conditions

HE Wei, ZHU Tianle, LI Jing

期刊论文

Genetic Study Identifies CBLN4 as a Novel Susceptibility Gene for Accident Proneness

Shu-lin Zhang,Hui-qing Jin,Yang Song,Wan-sheng Yu,Liang-dan Sun

期刊论文

把握生物经济时代精神,实践进步的幸福观

甘自恒

期刊论文

Nanostructure and reactivity of soot from biofuel 2,5-dimethylfuran pyrolysis with CO

Lijie ZHANG, Kaixuan YANG, Rui ZHAO, Mingfei CHEN, Yaoyao YING, Dong LIU

期刊论文

基于本质安全的工业事故风险管理方法研究

吴宗之

期刊论文

Prognostic value of the 21-gene recurrence score in ER-positive, HER2-negative, node-positive breast

Jiayi Wu, Weiqi Gao, Xiaosong Chen, Chunxiao Fei, Lin Lin, Weiguo Chen, Ou Huang, Siji Zhu, Jianrong He, Yafen Li, Li Zhu, Kunwei Shen

期刊论文

Total phosphorus accident pollution and emergency response study based on geographic information system

Aifeng Zhai, Xiaowen Ding, Lin Liu, Quan Zhu, Guohe Huang

期刊论文

安全理论基本假说

于海湧,李芳

期刊论文

“7·23”旅客列车事故的重要启示

孙永福

期刊论文

Effect of pressure on gasification reactivity of three Chinese coals with different ranks

Chunyu LI, Jiantao ZHAO, Yitian FANG, Yang WANG

期刊论文