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Fujita-type Phenomenon of the Nonlocal Diffusion Equations with Localized Source
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作者 Lili YANG Zhongping LI 《数学研究及应用:英文版》 CSCD 2019年第2期171-180,共10页
In this paper, we investigate the Cauchy problem for the nonlocal diffusion system with localized source ut = J*u-u + a(x)v~p, v_t = J*v-v + a(x)u~q. We first prove that the Fujita curve is(pq)_c*-= 1+max{p+1, q+1}bas... In this paper, we investigate the Cauchy problem for the nonlocal diffusion system with localized source ut = J*u-u + a(x)v~p, v_t = J*v-v + a(x)u~q. We first prove that the Fujita curve is(pq)_c*-= 1+max{p+1, q+1}based on whether there exist global solutions, thatis, if 1 < pq(pq)_c,then every nonnegative solution blows up in finite time, but for pq >(pq)_c,there exist both global and non-global solutions to the problem. Furthermore, we establish the secondary critical curve on the space-decay of initial value at infinity. 展开更多
关键词 NONLOCAL diffusion system Fujita CRITICAL CURVE secondary CRITICAL CURVE global EXISTENCE BLOW-UP
Detection of void and metallic inclusion in 2D piezoelectric cantilever beam using impedance measurements
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作者 S.SAMANTA S.S.S.NANTHAKUMAR +1 位作者 R.K.ANNABATTULA X.ZHUANG 《结构与土木工程前沿:英文版》 EI CSCD 2019年第3期542-556,共15页
The aim of current work is to improve the existing inverse methodology of void-detection based on a target impedance curve,leading to quick-prediction of the parameters of single circular void.In this work,mode-shape ... The aim of current work is to improve the existing inverse methodology of void-detection based on a target impedance curve,leading to quick-prediction of the parameters of single circular void.In this work,mode-shape dependent shifting phenomenon of peaks of impedance curve with change in void location has been analyzed.A number of initial guesses followed by an iterative optimization algorithm based on univariate method has been used to solve the problem.In each iteration starting from each initial guess,the difference between the computationally obtained impedance curve and the target impedance curve has been reduced.This methodology has been extended to detect single circular metallic inclusion in 2D piezoelectric cantilever beam.A good accuracy level was observed for detection of flaw radius and flaw-location along beam-length,but not the precise location along beam-width. 展开更多
关键词 PIEZOELECTRICITY impedance CURVE mode shapes inverse problem FLAW DETECTION CURVE SHIFTING
快速消解-工作曲线法测定土壤中的铅 预览
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作者 王昊 薛园园 王学敏 《广州化工》 CAS 2019年第10期87-88,共2页
采用石墨炉原子吸收法测定土壤中的铅,前处理方法常使用湿法消解和微波消解,但是分别存在耗酸量大、过程复杂,二次赶酸等缺点,不适合进行大批量的土壤检测。研究使用石墨消解仪-盐酸+硝酸+氢氟酸快速消解土壤,并使用同时消解的土壤标准... 采用石墨炉原子吸收法测定土壤中的铅,前处理方法常使用湿法消解和微波消解,但是分别存在耗酸量大、过程复杂,二次赶酸等缺点,不适合进行大批量的土壤检测。研究使用石墨消解仪-盐酸+硝酸+氢氟酸快速消解土壤,并使用同时消解的土壤标准物质绘制工作曲线,减小和消除了基体干扰和系统误差,精密度和准确度较好,符合检测要求。 展开更多
关键词 快速消解 工作曲线
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浅析重载铁路线路曲线的常见病害及养护维修 预览
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作者 王悦 《中小企业管理与科技》 2019年第17期133-134,共2页
随着我国社会经济的不断发展,对铁路运输需求量越来越大,重载铁路运输由于负荷较大,任务较重,在运行过程中通常会发生一些病害而影响重载运输质量。论文主要针对重载铁路线路曲线常见病害及养护维修措施进行探究。
关键词 重载铁路 曲线 常见病害 养护措施
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Predicting the entire soil-water characteristic curve using measurements within low suction range
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作者 YE Yun-xue ZOU Wei-lie +1 位作者 HAN Zhong LIU Xiao-wen 《山地科学学报:英文版》 SCIE CSCD 2019年第5期1198-1214,共17页
The soil-water characteristic curve(SWCC) is widely used in the design and evaluation in the practice of geotechnical and geoenvironmental engineering such as the slope stability under the influence of environmental f... The soil-water characteristic curve(SWCC) is widely used in the design and evaluation in the practice of geotechnical and geoenvironmental engineering such as the slope stability under the influence of environmental factors. The SWCC has distinct features in the capillary and adsorption zones due to different physical mechanisms. Measurements of the SWCC are typically limited within the capillary zone(i.e., low suction range). It is cumbersome and time-consuming to measure the SWCC in the adsorption zone(i.e., high suction range). This study presents a simple method to predict the entire SWCC within both the capillary and adsorption zones, using measured data only from low suction range(e.g., from 0 to 500 kPa). Experimental studies were performed on a completely weathered granite residual soil to determine its entire SWCC from saturated to dry conditions. The resultant SWCC, along with the SWCC measurements of 14 soils reported in the literature, were used to validate the proposed method. The results indicate that the proposed method has good consistency with a wide array of measured data used in this study. The proposed method is easy to use as it only requires a simple parameter calibration for a commonly used SWCC model. It can be used to improve the reliability in the prediction of the SWCC over the entire suction range when measurements are limited within the low suction range. 展开更多
关键词 UNSATURATED SOILS SOIL-WATER characteristic CURVE CAPILLARY Adsorption Prediction
多段曲线拟合弹齿式枝条捡拾参数反求法求解 预览
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作者 李辉 杨爱茜 +3 位作者 李建平 王利源 刘俊峰 杨欣 《农机化研究》 北大核心 2019年第9期34-39,共6页
为了达到矮砧集约栽培种植模式果园行间果树枝条高效还田处理的目的,研究了拖拉机悬挂式枝条粉碎设备的关键部件—弹齿滚筒式枝条捡拾器。通过分段设计弹齿在空间的理想运行姿态及运动轨迹,来满足捡拾枝条过程中不同阶段的捡拾要求。使... 为了达到矮砧集约栽培种植模式果园行间果树枝条高效还田处理的目的,研究了拖拉机悬挂式枝条粉碎设备的关键部件—弹齿滚筒式枝条捡拾器。通过分段设计弹齿在空间的理想运行姿态及运动轨迹,来满足捡拾枝条过程中不同阶段的捡拾要求。使用反求法,建立弹齿滚筒式捡拾器的数学模型,编制人机对话软件,对滑道中心函数曲线求解,并进行曲线拟合及其数据后处理,同时优化曲柄半径L1、弹齿长度L2、弹齿角度β、十字架半径r、弹齿与曲柄夹角θ等变量参数,以达到捡拾枝条时各项参数最佳匹配的性能要求。优化后的具体参数为:L1=50mm、L2=170mm、r=80mm、θ=55°,α在一个周期内顺时针旋转,将其分成了5段,即α1、α2、α3、α4、α5,相对应转动的角度分别是45°、45°、90°、90°、90°。与α每段对应的β值,即β1、β2、β3、β4、β5,对应的角度范围分别是:65° >β1 >60°,60° >β2 >-70°,-70° >β3 >-220°,-220° >β4 >-280°,-280° >β5 >-295°(65°)。 展开更多
关键词 捡拾器 枝条 弹齿 曲线 拟合
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高温作业下专用服装设计分析 预览
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作者 张倩倩 张坤 《科技创新导报》 2019年第7期133-134,共2页
在高温环境下工作时,人们需要穿着专用服装以避免灼伤。专用服装通常由三层织物材料构成,记为I、II、III层,其中I层与外界环境接触,III层与皮肤之间还存在空隙,将此空隙记为IV层。为设计这种专用服装,将体内温度控制在37℃的假人放置在... 在高温环境下工作时,人们需要穿着专用服装以避免灼伤。专用服装通常由三层织物材料构成,记为I、II、III层,其中I层与外界环境接触,III层与皮肤之间还存在空隙,将此空隙记为IV层。为设计这种专用服装,将体内温度控制在37℃的假人放置在实验室的高温环境中,对环境温度为75℃、II层厚度为6mm、IV层厚度为5mm、工作时间为90min的情形开展实验,测量得到假人皮肤外侧的温度。为了降低研发成本、缩短研发周期,可以通过数学建模确定假人皮肤外侧的温度变化情况,并解决相关问题。 展开更多
关键词 热传导微分方程模型 CURVE FITTING Tool 非线性规划 目标规划模型 专用服装
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从两道例题看高等数学知识的前后贯通 预览
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作者 李宜阳 《高等数学研究》 2019年第1期124-125,共2页
本文通过探究偏导数几何意义方面的两道例题,将涉及到偏导数,空间曲面,空间曲线,直线,平面,二元函数的标准线性近似等内容融会贯通.
关键词 偏导数 空间曲线 空间曲面 切线 切平面
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有轨电车曲线啸叫噪声试验分析
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作者 赵悦 何远鹏 +3 位作者 韩健 肖新标 连逢逾 王蕊 《机械工程学报》 EI CAS CSCD 北大核心 2019年第10期133-141,共9页
曲线啸叫噪声是城市轨道交通中一个亟待解决的问题,但目前国内对其研究较少。以70%低地板有轨电车通过嵌入式轨道小半径曲线时为研究对象,通过测试和分析,研究其轮轨啸叫噪声特性及产生机理。测试曲线半径分别是25 m和50 m,试验速度分别... 曲线啸叫噪声是城市轨道交通中一个亟待解决的问题,但目前国内对其研究较少。以70%低地板有轨电车通过嵌入式轨道小半径曲线时为研究对象,通过测试和分析,研究其轮轨啸叫噪声特性及产生机理。测试曲线半径分别是25 m和50 m,试验速度分别是3~9 km/h和4~20 km/h。试验过程中轮轨接触表面状态分别考虑了自然状态、水润滑状态、油润滑状态和固体润滑状态。测试结果表明,未润滑状态下的车外标准点噪声LAeq在56~91 dB(A),其中87%~92%的工况发生啸叫或轻微啸叫;导向轮对(第一位轮对)内侧车轮发出的啸叫噪声最为显著,其产生机理是轮轨间的横向蠕滑激励车轮1 811 Hz频率处(0,3)轴向模态振动,从而产生强烈的单频振动并发出啸叫。试验对比了不同润滑状态(水、润滑油、固体润滑剂)对啸叫的控制效果,测试结果表明采取润滑后,测试工况中发生啸叫或轻微啸叫的比例降低到19%~50%,车外噪声LAeq显著降低。研究补充了国内在有轨电车-嵌入式轨道曲线啸叫方面试验数据,并基于试验数据基本弄清了有轨电车-嵌入式轨道曲线啸叫噪声的产生机理。 展开更多
关键词 啸叫 曲线 有轨电车 嵌入式轨道 润滑
Learning curve of enhanced recovery after surgery program in open colorectal surgery 预览
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作者 Varut Lohsiriwat 《世界胃肠外科杂志:英文版(电子版)》 2019年第3期169-178,共10页
BACKGROUND Enhanced recovery after surgery (ERAS) reduces hospitalization and complication following colorectal surgery. Whether the experience of multidisciplinary ERAS team affects patients’ outcomes is unknown. AI... BACKGROUND Enhanced recovery after surgery (ERAS) reduces hospitalization and complication following colorectal surgery. Whether the experience of multidisciplinary ERAS team affects patients’ outcomes is unknown. AIM To evaluate and establish a learning curve of ERAS program for open colorectal surgery. METHODS This was a review of prospectively collected database of 380 “unselected” patients undergoing elective “open” colectomy and/or proctectomy under ERAS protocol from 2011 (commencing ERAS application) to 2017 in a university hospital. Patients were divided into 5 chronological groups (76 cases per quintile). Surgical outcomes and ERAS compliance among quintiles were compared. Learning curves were calculated based on criteria of optimal recovery: defined as absence of major postoperative complications, discharge by postoperative day 5, and no 30-d readmission. RESULTS Hospitalization more than 5 d occurred in 22.6%(n = 86), major complication was present in 2.9%(n = 11) and 30-d readmission rate was 2.4%(n = 9) accounting for unsuccessful recovery of 25%(n = 95). Conversely, the overall rate of optimal recovery was 75%. The optimal recovery significantly increased from 57.9% in 1st quintile to 72.4%-85.5% in the following quintiles (P < 0.001). Average compliance with ERAS protocol gradually increased over the time - from 68.6% in 1st quintile to 75.5% in 5th quintile (P < 0.001). The application of preoperative counseling, nutrition support, goal-directed fluid therapy, O-ring wound protector and scheduled mobilization significantly increased over the study period.CONCLUSION A number of 76 colorectal operations are required for a multidisciplinary team to achieve a significantly higher rate of optimal recovery and high compliance with ERAS program for open colorectal surgery. 展开更多
关键词 Enhanced recovery after SURGERY ERAS COLON RECTUM SURGERY Learning curve OUTCOME COMPLIANCE
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Effects of Nitrogen-Containing Biodegradation Enhancers on Sorption of n-Hexadecane in Soil-Water System 预览
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作者 Fan Xingyu Wu Jiang +3 位作者 Chen Boshui Gu Kecheng Ding Jianhua Wu Ke 《中国炼油与石油化工:英文版》 SCIE CAS 2019年第1期110-116,共7页
Effects of nitrogen-containing biodegradation enhancers(methyl diethanolamine oleate(MDEAO) and oleic diethanolamide(ODEA)) on the adsorption of n-hexadecane in soil were studied by laboratory batch experiments. The p... Effects of nitrogen-containing biodegradation enhancers(methyl diethanolamine oleate(MDEAO) and oleic diethanolamide(ODEA)) on the adsorption of n-hexadecane in soil were studied by laboratory batch experiments. The partition coefficients(Kd values) of n-hexadecane sorption in soil-water system and those partition coefficients normalized to organic matter(Koc values) were both determined. The adsorption isotherm curve of n-hexadecane in soil-water system was plotted. The measured results demonstrated that Koc values changed in the soil-water system with different enhancers but are relatively invariant for the soil at the same site. The Kd values rose with the increase of the organic matter content in different soil. The average values of Koc in the soil-water system with MDEAO, ODEA,and blank soil were 0.412, 0.252,and 0.309, respectively. The critical micelle concentration of ODEA and MDEAO was 0.7 mg/L and 1.9 mg/L, respectively,denoting that the solubilization capacity of ODEA was much stronger than MDEAO in the soil-water system. Consequently,the adsorption of MDEAO onto the solid surface increased the organic matter content in soil,which could make it more effective in enhancing the n-hexadecane adsorption. On the contrary, ODEA could inhibit the adsorption of n-hexadecane because of its less adsorption rate onto the soil particle surface and higher concentration in the soil-water system. According to the correlation coefficients, it was found that both the Henry linear and the Freundlich nonlinear isotherm sorption models were fitted to the data very well, however the Freundlich model was better than the Henry model. 展开更多
关键词 methyl DIETHANOLAMINE OLEATE oleic diethanolamide adsorption ISOTHERMAL curve soil
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车辆弯道避撞控制研究 预览
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作者 张佳佳 魏民祥 +2 位作者 项楚勇 吴树凡 邢德鑫 《汽车技术》 CSCD 北大核心 2019年第3期13-17,共5页
针对弯道路段前方行驶车辆紧急制动的危险工况,提出一种弯道换道的主动避撞控制算法。搭建弯道避撞模型,利用弯道安全距离模型实时判断是否处于危险工况,在危险工况下,利用逆动力学模型获得所需的转向盘转角,依据提出的换道路径进行转... 针对弯道路段前方行驶车辆紧急制动的危险工况,提出一种弯道换道的主动避撞控制算法。搭建弯道避撞模型,利用弯道安全距离模型实时判断是否处于危险工况,在危险工况下,利用逆动力学模型获得所需的转向盘转角,依据提出的换道路径进行转向避撞,为满足稳定性要求,采用扩展卡尔曼滤波对横摆角速度等关键状态变量进行实时跟踪。利用PreScan与MATLAB/Simulink障碍物。 展开更多
关键词 弯道 换道避撞 扩展卡尔曼滤波
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Prediction of sedimentation in reservoirs by combining catchment based model and stream based model with limited data 预览
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作者 Abebe Tadesse Wenhong Dai 《国际泥沙研究:英文版》 SCIE 2019年第1期27-37,共11页
Estimation of sedimentation in reservoirs helps in the management and design of the reservoir's useful capacity.This research was done on the Awash River basin at the Koka Dam Reservoir in Ethiopia.The method appl... Estimation of sedimentation in reservoirs helps in the management and design of the reservoir's useful capacity.This research was done on the Awash River basin at the Koka Dam Reservoir in Ethiopia.The method applied was the loose integration of the Soil and Water Assessment Tool(SWAT)model and Hydrologic Engineering Center-River Analysis System(HEC-RAS)model for the estimation of the sediment load reaching the reservoir.The SWAT model was used for the estimation of erosion at the catchment level,and the HEC-RAS model was applied to estimate the sediment transport in the river channel.The implemented method allows sedimentation in the floodplains and bed shear stress to be considered in the sediment modeling,which cannot be considered in the SWAT model.In addition,the river cross sectional properties and the hydrodynamic processes in the rivers were considered in the modeling process.The data used in this study are a combination of i)observed data collected by government agencies,ii)data available online in data repositories,and iii)data extracted from remote sensing in the Shuttle Radar Topographic Mission(SRTM)Digital Elevation Model(DEM).The calibration and validation of the SWAT model was done by using Sequential Uncertainty Fitting(SUIF-2)calibration and validation tools.The HEC-RAS model was calibrated by adjusting the roughness factor.The output from the integrated approaches gives better estimates of flow and sediment near the inlet to the reservoir,with coefficients of determination of 0.85 and 0.67,respectively,and Nash Sutcliffe coefficients of model fit efficiency of 0.90 and 0.62,respectively,for daily simulations. 展开更多
关键词 Reservoir SEDIMENTATION Awash River SWAT HEC-RAS Rating curve
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Effectiveness of Parkland formula in the estimation of resuscitation fluid volume in adult thermal burns
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作者 Geley Ete Gaurav Chaturvedi +1 位作者 Elvino Barreto Kingsly Paul M 《中华创伤杂志:英文版》 CAS CSCD 2019年第2期113-116,共4页
Purpose:Acute burn resuscitation in initial 24 h remains a challenge to plastic surgeons.Though various formulae for fluid infusion are available but consensus is still lacking,resulting in under resuscitation or over... Purpose:Acute burn resuscitation in initial 24 h remains a challenge to plastic surgeons.Though various formulae for fluid infusion are available but consensus is still lacking,resulting in under resuscitation or over resuscitation.Parkland formula is widely used but recently its adequacy is questioned in studies.This study was conducted to see how closely the actual volume of fluid given in our center matches with that of calculated volume by Parkland formula.Methods:All patients admitted with more than 20% flame burn injury and within 8 h of incident were included in this study.Crystalloid solution for infusion was calculated as per Parkland formula;however,it was titrated according to the urine output.Data on fluid infusion were collected from patient's inpatient records and analyzed.Results:The study included a total of 90 patients,about 86.7% (n =78) of the patients received fluid less than the calculated Parkland formula.Rate of fluid administered over 24 h in our study was 3.149 mL/kg/ h.Mean hourly urine output was found to be 0.993 mL/kg/h.The mean difference between fluid administered and fluid calculated by Parkland formula was 3431.825 mL which was significant (p < 0.001).Conclusion:The study showed a significant difference in the fluid infused based on urine output and the fluid calculated by Parkland formula.This probably is because fluid infused based on end point of resuscitation was more physiological than fluid calculated based on formulae. 展开更多
关键词 BURN RESUSCITATION Parkland FORMULA URINE output PHYSIOLOGICAL curve
Change in arterial tumor perfusion is an early biomarker of lenvatinib efficacy in patients with unresectable hepatocellular carcinoma 预览
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作者 Hidekatsu Kuorda Tamami Abe +7 位作者 Yudai Fujiwara Takuya Okamoto Miki Yonezawa Hiroki Sato Kei Endo Takayoshi Oikawa Kei Sawara Yasuhiro Takikawa 《世界胃肠病学杂志:英文版》 SCIE CAS 2019年第19期2365-2372,共8页
BACKGROUND Lenvatinib is one of the first-line tyrosine kinase inhibitors used for unresectable hepatocellular carcinoma (HCC). In the present study, we evaluated the potential of early changes in the time-intensity c... BACKGROUND Lenvatinib is one of the first-line tyrosine kinase inhibitors used for unresectable hepatocellular carcinoma (HCC). In the present study, we evaluated the potential of early changes in the time-intensity curve (TIC) of arterial phase on contrastenhanced ultrasound (CEUS) as early imaging biomarkers of lenvatinib efficacy. AIM To evaluate the potential of the early changes in the TIC of CEUS as early imaging biomarkers of lenvatinib efficacy in patients with unresectable HCC. METHODS We analyzed 20 consecutive patients with unresectable HCC treated with lenvatinib from March to November 2018. Tumor response at 8 wk was assessed by computed tomography using the modified Response Evaluation Criteria in Solid Tumors (mRECIST). CEUS was performed at baseline before treatment (Day 0) and on day 7 (Day 7), and the images were analyzed in the arterial phase for 20 seconds after the contrast agent arrived at the target tumor. Three perfusion parameters were extracted from the TICs: the slope of wash-in (Slope), time to peak (TTP) intensity, and the total area under the curve (AUC) during wash-in. The rate of change in the TIC parameters between Day 0 and Day 7 was compared between treatment responders and non-responders based on mRECIST. RESULTS The rate of change for all TIC parameters showed significant differences between the responders (n = 9) and non-responders (n = 11)(Slope, P = 0.025;TTP, P =0.004;and AUC, P = 0.0003). The area under the receiver operating curve values for slope, TTP, and AUC for the prediction of responders were 0.805, 0.869, and 0.939, respectively. CONCLUSION CEUS may be useful for the early prediction of tumor response to lenvatinib therapy in patients with unresectable HCC. 展开更多
关键词 Hepatocellular carcinoma Lenvatinib CONTRAST-ENHANCED ULTRASOUND Timeintensity CURVE
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交流电弧炉电气运行仿真研究 预览
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作者 沈南飞 《冶金动力》 2019年第2期11-15,共5页
应用MATLAB语言的仿真功能,对创建的电弧炉数学模型在不同的电参数条件下进行仿真,形成电气图、供电效率曲线图和电气运行曲线图,结合约束条件,定量给出电弧炉合理的操作区间,为电弧炉运行优化和供电制度的建立提供理论支持。
关键词 交流电弧炉 数学模型 电气图 运行曲线 仿真研究
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Hot Deformation Behavior of a New Nuclear Use Reduced Activation Ferritic/Martensitic Steel
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作者 Chao Liu Ming-Chun Zhao +5 位作者 Tuguldur Unenbayar Ying-Chao Zhao Bin Xie Yan Tian Yi-Yin Shan Ke Yang 《金属学报:英文版》 SCIE EI CAS CSCD 2019年第7期825-834,共10页
The hot deformation behavior and workability of a new reduced activation ferritic/martensitic steel named SIMP steel for accelerator-driven system were studied. The flow curve and its microstructure were studied at 90... The hot deformation behavior and workability of a new reduced activation ferritic/martensitic steel named SIMP steel for accelerator-driven system were studied. The flow curve and its microstructure were studied at 900-1200 ℃ and strain rate range of 0.001-10 s^-1. The results showed that the deformation behavior of the SIMP steel during hot compression could be manifested by the Zener-Hollomon parameter in an exponent-type equation. Based on the obtained constitutive equation, the calculated flow stresses were in agreement with the experimentally measured ones, and the average activity energies Qdrv and QHw for the initiation of dynamic recrystallization and the peak strain were calculated to be 476.1 kJ/mol and 462.7 kJ/mol, respectively. Furthermore, based on the processing maps and microstructure evolution, the optimum processing condition for the SIMP steel was determined to be 1050-1200 ℃/0.001-0.1s^-1. 展开更多
关键词 REDUCED ACTIVATION ferritic/martensitic steel Hot DEFORMATION Flow CURVE CONSTITUTIVE equation Processing map
Numerical investigation of circle defining curve for two-dimensional problem with general boundaries using the scaled boundary finite element method
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作者 Chung Nguyen VAN 《结构与土木工程前沿:英文版》 EI CSCD 2019年第1期92-102,共11页
The scaled boundary finite element method (SBFEM)is applied to the static analysis of two dimensional elasticity problem,boundary value problems domain with the domain completely described by a circular defining curve... The scaled boundary finite element method (SBFEM)is applied to the static analysis of two dimensional elasticity problem,boundary value problems domain with the domain completely described by a circular defining curve. The scaled boundary finite element equations is formulated within a general framework integrating the influence of the distributed body force,general boundary conditions,and bounded and unbounded domain.This paper investigates the possibility of using exact geometry to form the exact description of the circular defining curve and the standard finite element shape function to approximate the defining curve.Three linear elasticity problems are presented to verify the proposed method with the analytical solution.Numerical examples show the accuracy and efficiency of the proposed method,and the performance is found to be better than using standard linear element for the approximation defining curve on the scaled boundary method. 展开更多
关键词 EXACT GEOMETRY circular defining CURVE general boundaries SBFEM
Density effect and self-thinning in Eucalyptus urophylla stands 预览
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作者 Zhiyang Lie Li Xue 《林业研究:英文版》 CAS CSCD 2019年第2期529-535,共7页
Density effects on the growth and self-thinning of Eucalyptus urophylla stands were examined for 7 years.The reciprocal equation of the competition-density(C–D)effect was used to describe the C–D effect in even-aged... Density effects on the growth and self-thinning of Eucalyptus urophylla stands were examined for 7 years.The reciprocal equation of the competition-density(C–D)effect was used to describe the C–D effect in even-aged pure stands of E.urophylla during course of self-thinning and showed a good fit to the data.The time trajectories of mean stem volume-density nearly paralleled the y-axis during early growth stages of stands,and then began to curve left.Finally,the mean stem volume-density trajectories of the low-,middle-and high-density stands tended to follow the self-thinning lines with slopes of-2.01,-1.90 and-1.99,respectively.With increasing physical time t,the biological timeτincreased rapidly during early growth stages and became slow gradually during later growth stages.Realized density-initial density curves tended to become more or less flat with increasing initial density,indicating the existence of an asymptotic value for density at a given time.The coefficientε,the reciprocal of which represents the asymptotic density at a given time,increased with increasing biological timeτ,indicating that the asymptotic density decreased with increasing stand age.Final yield Y(t)increased gradually with increasing stand age. 展开更多
关键词 C–D effect General LOGISTIC CURVE EUCALYPTUS urophylla Reciprocal EQUATION SELF-THINNING
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Estimation of peak runoff and frequency in an ungauged stream of a forested watershed for flood hazard mapping 预览
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作者 Refik Karagul Tarik Citgez 《林业研究:英文版》 CAS CSCD 2019年第2期555-564,共10页
frequencies.The aim of this research was to determine the measures needed to protect the towns and villages from this type of damage.Daily total precipitation data for 1975–2010 were analysed,and rainfall-runoff mode... frequencies.The aim of this research was to determine the measures needed to protect the towns and villages from this type of damage.Daily total precipitation data for 1975–2010 were analysed,and rainfall-runoff models developed to estimate the potential yearly maximum discharge from each stream of sub-watersheds dominated by forests and/or agriculture.This was then calculated for different frequencies of the yearly maximum discharge.Flood analysis and mapping was modified via the one-dimensional Hydrologic Engineering Centers-River Analysis System software to produce potential maximum discharge and geometric data for Kaynasli Creek.As the main creek of the sub-watershed,its crosssection was shown to be insufficient and incapable of containing the maximum discharge at the 100-year frequency presumed for the watershed,and subsequently was seen as having a high level of casualty risk.It was concluded that the one dimensional model could be useful,but 2D models were more suitable for these types of watersheds. 展开更多
关键词 Flood FREQUENCY ANALYSIS FLOODPLAIN MAPPING Flow simulation Hydrologic Engineering Centers-River ANALYSIS System(HEC-RAS) Soil Conservation Service Curve Number(SCS-CN)
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