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Visual cues modulate nest defense behavior in Japanese Tits:Insights from the appearance,posture and size of snake dummies
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作者 Dake Yin Jiangping Yu +4 位作者 Romain Lorrilliere Jiangping Jin Mingju E Longru Jin Haitao Wang 《Avian Research》 2025年第4期713-720,共8页
Predator dummies are usually used to explore the impact of predator features on the anti-predator behavior of birds.Previous studies have shown that the morphology and behavior of aerial predators can signal different... Predator dummies are usually used to explore the impact of predator features on the anti-predator behavior of birds.Previous studies have shown that the morphology and behavior of aerial predators can signal different threat levels to birds.However,whether subtle changes in ground predator dummies cause changes in the nest defense behavior of parent birds is unclear.In this study,we aimed to investigate whether Japanese Tits(Parus minor)exhibit different nest defense behaviors in response to experimentally manipulated variations in the appearance,posture,and size of virtual snake proxies(common nest predators).During the incubation period,we observed the nest defense behaviors of the parent tits against taxidermized Siberian Ratsnakes(Elaphe schrenckii)with varied characteristics and rubber-made model snakes.The tits exhibited more intense responses to taxidermized large(body length about 120 cm)coiled ratsnakes than to large coiled model snakes.They exhibited weaker responses to taxidermized small(body length about 20 cm)coiled ratsnakes than to taxidermized small sinusoidal ratsnakes.In addition,they exhibited more intense responses to taxidermized large coiled ratsnakes than to taxidermized small coiled ratsnakes,and more intense responses to taxidermized small sinusoidal ratsnakes than to large model snakes.However,there was no difference in the response of tits to taxidermized small sinusoidal ratsnakes and taxidermized large coiled ratsnakes,or to taxidermized small coiled ratsnakes and model snakes.Thus,the presence of scales,a sinusoidal posture,and a large body size of snake dummies can induce more intense behavioral responses in Japanese Tits.We suggested that Japanese Tits can discriminate subtle differences in ground predator dummies of nests and exhibit different nest defense behaviors. 展开更多
关键词 Ground predator of nest Japanese Tits Nest defense behavior Predator dummies
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Anthropometric Comparison of Three-Year-Old Nigerian Child and Crash Dummies
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作者 Ibrahim Abdullahi Rafukka Barkawi Bin Sahari +1 位作者 Abdulaziz Nuraini Arumugam Manohar 《Journal of Transportation Technologies》 2016年第4期192-199,共8页
In this work, anthropometric data measured from three-year-old Nigerian child were compared with United States anthropometric database collected by Snyder, 1977 which formed the basis of US anthropometry used today. F... In this work, anthropometric data measured from three-year-old Nigerian child were compared with United States anthropometric database collected by Snyder, 1977 which formed the basis of US anthropometry used today. Further comparison was also carried out with the dimensions of crash dummies: Hybrid III three-year-old (HIII 3YO) and Q3s dummies in order to determine the validity of using such crash dummies for safety evaluation of cars and child restraint systems (CRS) used for Nigerian children. Anthropometric survey was performed on 30 Nigerian children aged 2.5 to 3.5 years old. Twenty three standard measurements were taken from each child including the weight, height and circumferences etc. Various percentiles mean and standard deviation values were obtained and compared with international database. As observed, the dimensions of three-year-old Nigerian child appeared to be about 25% lower than US data reported by Snyder. Significant difference was also found between the dimensions of three-year-old Nigerian child and crash dummies. This study provides the external dimensions of 3-year-old Nigerian child that could be used for crash dummy and CRS design. 展开更多
关键词 ANTHROPOMETRY Crash dummies Child Restraint System Measurement Vehicle Safety
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Simulation and fabrication of vertical channel transistors with self-aligned high-κ metal gates using ion implantation for source/drain doping
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作者 Penghui Sun Yongkui Zhang Jun Luo 《Journal of Semiconductors》 2025年第12期62-70,共9页
In vertical channel transistors(VCTs),source/drain ion implantation(I/I)represents a significant technical challenge due to inherent three-dimensional structural constraints,which induce complications such as difficul... In vertical channel transistors(VCTs),source/drain ion implantation(I/I)represents a significant technical challenge due to inherent three-dimensional structural constraints,which induce complications such as difficulties in dummy gate forma-tion and shadowing effects of I/I.This article systematically investigates the impact of different implantation conditions on the performance of VCTs with and without dummy gates through TCAD simulation.It reveals the significant role of the lightly doped regions(LDRs)naturally formed due to ion implantation in source/drain of VCTs.Furthermore,it was found that VCT with-out dummy gates can achieve an approximately 27%increase in on-state current(Ion)under the same implantation conditions,and can greatly simplify the process flow and reduce costs.Finally,N-type and P-type VCTs were successfully fabricated using this implantation method. 展开更多
关键词 vertical channel transistor source/drain ion implantation on-state current dummy gates
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医用回旋加速器工作状态下束流稳定性分析 被引量:5
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作者 徐绪党 刘标 +1 位作者 李殿富 杨伟 《中国医疗设备》 2011年第3期15-17,共3页
目的分析医用回旋加速器两种工作状态下加速束流的基本特征;监测加速器在较高负荷运行条件下的束流稳定性。方法利用高纯氢气作为离子源气体,分别自加速末端提取单、双束流,测试两种条件下离子源电流、引出束流及加速环境的真空度随时... 目的分析医用回旋加速器两种工作状态下加速束流的基本特征;监测加速器在较高负荷运行条件下的束流稳定性。方法利用高纯氢气作为离子源气体,分别自加速末端提取单、双束流,测试两种条件下离子源电流、引出束流及加速环境的真空度随时间的变化趋势。结果真空腔的真空度、离子源电流及准直器电流在双束流测试时变化幅度相对较大,两种测试条件下,真空度及离子源呈缓慢递增趋势,准直器电流呈缓慢递减趋势,60min后趋于稳定。结论正常工作状态下,单束流比双束流轰靶的束流稳定性强,且两种条件下束流最终处于较稳定的工作状态。应优先选择单束流工作模式。 展开更多
关键词 医用回旋加速器 准直器 束流 稳定性 测试用Dummy靶
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Cointegration analysis with structural changes between consumption and economic growth in China 被引量:3
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作者 郭建平 何建敏 《Journal of Southeast University(English Edition)》 EI CAS 2006年第2期238-241,共4页
In order to investigate the existence of a stable long-run equilibrium relationship between economic growth and consumption in China, the relationship between the gross domestic product (GDP) and consumption in Chin... In order to investigate the existence of a stable long-run equilibrium relationship between economic growth and consumption in China, the relationship between the gross domestic product (GDP) and consumption in China was investigated by the cointegration analysis method. Using the Engle-Granger (EG) test and considering the possibility of structural changes, the impact of external economic shocks on the long-run equilibrium relationship between economic growth and consumption in China was analyzed. Analysis results show that without considering structural changes, the EG test cannot detect cointegration in the series subjected to structural changes; in considering structural changes, cointegration is successfully detected by specifying the dummy variable. In addition, the error correction models were constructed in different periods. This study verifies the existence of a long-run equilibrium relationship between economic growth and consumption in China, and this relationship has significantly changed in 1989 and 1997, respectively. 展开更多
关键词 cointegration with structural changes economic growth dummy variable CONSUMPTION error correction model
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BIOSID Dummy撞击实验的计算机模拟研究 被引量:2
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作者 赵隆茂 《爆炸与冲击》 EI CAS CSCD 北大核心 2001年第3期173-178,共6页
给出了一个BIOSIDdummy侧撞有限元模拟结果 ,和实验结果比较验证后可知该模型是可靠有效的。这一模型不仅可以用于任何侧撞情况下车辆乘员损伤防护模拟的研究 。
关键词 BIOSID DUMMY 有限元模拟 VC TTI 撞击实验 车辆安全性 乘员损伤 汽车
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Hybrid-Ⅲ型Dummy刚性有限元模型的研究改进 被引量:2
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作者 赵隆茂 《汽车工程》 EI CSCD 北大核心 2000年第5期306-309,共4页
Hybrid-Ⅲ型Dummy刚性有限元模型因具有独特的优点已被广泛地用于评定汽车乘员安全系统有效性的模拟研究中。在汽车安全带的模拟中发现现有模型存在较大的缺陷。本文提供了一个改进模型,利用实验结果验证,改进模型是合理有效的。该模型... Hybrid-Ⅲ型Dummy刚性有限元模型因具有独特的优点已被广泛地用于评定汽车乘员安全系统有效性的模拟研究中。在汽车安全带的模拟中发现现有模型存在较大的缺陷。本文提供了一个改进模型,利用实验结果验证,改进模型是合理有效的。该模型可为乘员安全保护系统的评估提供更为精确的模拟结果。 展开更多
关键词 Hybrid-Ⅲ型Dummy 刚性有限元模型 改进 汽车
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EUROSID-I Dummy的结构及有限元模型 被引量:1
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作者 赵隆茂 《太原理工大学学报》 CAS 1999年第2期188-190,共3页
描述了EUROSID-I型dummy的结构及有限元模型,以便对该dummy进行计算机模拟。该模型不仅可用于各种侧向撞击的研究,也可用于dummy的改进和发展。
关键词 DUMMY 计算机模拟 有限元模型 汽车 侧撞防护
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单盲双模拟针灸临床试验设计思路与实践——以“手针和电针治疗绝经烘热疗效比较”研究为例
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作者 石文英 章薇 《World Journal of Acupuncture-Moxibustion》 CAS CSCD 2023年第4期367-371,共5页
Randomized controlled trial(RCT)is the golden standard for evaluation of clinical evidence.To assess the effect of acupuncture,due to the specificity of acupuncture intervention,the blinding and control methods are th... Randomized controlled trial(RCT)is the golden standard for evaluation of clinical evidence.To assess the effect of acupuncture,due to the specificity of acupuncture intervention,the blinding and control methods are the difficulties in study design.It is not practical to blind investigators,participants and evaluators simultaneously.At present,blinding is generally conducted for the participants and evaluators in clinical trial.We took a comparative study of manual acupuncture and electroacupuncture for menopausal hot flush as an example to explore a new way with the reference of double-dummy design in new drug study.A single-blind and double-dummy clinical trial model of acupuncture was established.Based on individual acupuncture intervention in each group,the placebo intervention was combined to ensure the form consistency of two groups.Such a study design may eliminate non-specific effect of acupuncture,and can be conductive to comparing the specific effect of acupuncture and can provide the references and regimens for study design. 展开更多
关键词 Single-blind Double dummy Clinical trial Randomized controlled trial(RCT) MENOPAUSAL Hot flush Acupuncture Electroacupuncture Manual acupuncture
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开放式全自动生化仪加样性能确认研究
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作者 叶解明 丁国清 《中国医疗器械杂志》 CAS 2005年第4期277-282,共6页
介绍一种评价新型全自动生化仪加样性能的方法。用色素法对样品针的加样性能,称重法对试剂针的加样性能以及Dummy量进行确认,并对不同情况下的Dummy量进行比较研究,为应用全自动生化分析仪提供了有价值的参考。
关键词 样品加样 试剂加样 Dummy量 色素法 称重法
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EUROSID-Ⅰ型Dummy的计算机模拟
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作者 赵隆茂 《太原理工大学学报》 CAS 1999年第3期312-315,共4页
在介绍了EUROSID-I型Dummy的有限元模型的基础上,给出了对EUROSID-I型Dummy的计算机数值模拟结果及分析。通过对有关试验结果的验证,可知该模型是合理有效的。
关键词 DUMMY 计算机模拟 汽车 安全性 EUROSID-I型
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基于SPH方法的二维液舱晃荡特性研究 被引量:3
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作者 张之凡 王越美 +2 位作者 李昌良 张桂勇 宗智 《船舶力学》 EI CSCD 北大核心 2024年第5期676-688,共13页
本文基于流固耦合动力学理论,建立二维液舱晃荡的光滑粒子流体动力学模型,并引入Dummy边界处理固定边界问题。首先,与实验结果对比验证模型的有效性;随后,分析不同横摇激励、多种载液率下自由液面的运动规律,研究液体抨击舱壁产生的压... 本文基于流固耦合动力学理论,建立二维液舱晃荡的光滑粒子流体动力学模型,并引入Dummy边界处理固定边界问题。首先,与实验结果对比验证模型的有效性;随后,分析不同横摇激励、多种载液率下自由液面的运动规律,研究液体抨击舱壁产生的压力特性;在此基础上,设计单一隔板和组合隔板等不同制荡结构,探究共振频率、30%载液率下,自由液面形态和壁面冲击压力的特性。结果表明:在共振频率下,横摇幅值对压力峰值的影响最大;随着载液率的增加,壁面抨击压力双峰特性逐渐消失;当隔板尺度较小时,T型隔板更有利于降低压力的整体水平;双T型隔板可有效降低舱底冲击。 展开更多
关键词 SPH方法 Dummy边界 液舱晃荡 抨击压力 隔板结构设计
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Synthesis and Solid Phase Extraction Performance Study of NNAL-specific Molecularly Imprinted Polymers Using Dummy Templates 被引量:2
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作者 张志丹 郑赛晶 +3 位作者 杨俊 王维妙 刘百战 朱晓兰 《Chinese Journal of Chemical Physics》 SCIE CAS CSCD 2013年第3期361-368,I0004,共9页
Dummy molecularly imprinted polymers (DMIPs) for 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL) were produced using three structural analogues as dummy template molecules. The chosen analogues were 4-(a... Dummy molecularly imprinted polymers (DMIPs) for 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL) were produced using three structural analogues as dummy template molecules. The chosen analogues were 4-(acetymethylamino)-1-(3-pyridyl)-butanol, 4- (methylamino)-1-(3-pyridyl)-1-butanol, and 1-(3-pyridyl)-1,4,-butanediol. The molecular recognition characteristics of the produced polymers were evaluated by X-ray photoelec- tron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FT-IR). Interactions between NNAL and methacrylic acid should be cooperative hydrogen bonds while the ni- trogen atom of the pyridine ring and the oxygen atom of the nitroso group in NNAL are two of the hydrogen-bond acceptors. It was further demonstrated that DMIP synthesized by 4-(acetymethylamino)-1-(3-pyridyl)-butanol had the best binding performance by XPS and FT-IR. Then dummy molecularly imprinted solid phase extraction (DMISPE) was developed for the determination of the analyte using the hit polymer as the sorbing material. Under optimal conditions, the recovery of NNAL dissolved in standard solution reached 93%. And the investigated polymer exhibited much higher binding of NNAL when nicotine was acted as the competitive molecule. Also the proposed method was applied to the measurement of NNAL spiked in blank urine samples with recoveries ranging from 87.2% to 101.2%. 展开更多
关键词 Molecularly imprinted polymer Dummy template 4-(Methylnitrosamino)-1-(3-pyridyl)-1-butanol Solid phase extraction
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一种低电荷注入误差的开关电流电路 被引量:2
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作者 虞海燕 林争辉 张海飞 《微电子学》 CAS CSCD 北大核心 2004年第5期589-592,596,共5页
 对限制开关电流电路(SI)精度的主要因素以及开关电荷注入误差等问题进行了详细的分析。在此基础上,提出了两种消除开关电荷注入误差的可能结构:在常电压开关(CVS)基础上的dummy开关结构和基于CVS的全差分结构。其主要思想是将与信号...  对限制开关电流电路(SI)精度的主要因素以及开关电荷注入误差等问题进行了详细的分析。在此基础上,提出了两种消除开关电荷注入误差的可能结构:在常电压开关(CVS)基础上的dummy开关结构和基于CVS的全差分结构。其主要思想是将与信号大小有关的电荷注入误差变为与信号无关的电荷注入误差。并以此为基础,采用dummy结构或全差分结构,进一步消除该误差。用0.35μm模型参数进行了HSPICE仿真,结果证明,该结构能很好地降低电荷注入误差,提高SI电路的精度。 展开更多
关键词 开关电流电路 电荷注入误差 常电压开关 全差分结构 dummy管
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Efficacy and safety of Shenyankangfu Tablet,a Chinese patent medicine,for primary glomerulonephritis:A multicenter randomized controlled trial 被引量:11
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作者 Jie Wu Shu-wei Duan +41 位作者 Hong-tao Yang Yue-yi Deng Wei Li Ya-ni He Zhao-hui Ni Yong-li Zhan Shan Lin Zhi-yong Guo Jun Zhu Jing-ai Fang Xu-sheng Liu Li-hua Wang Rong Wang Nian-song Wang Xiao-hong Cheng Li-qun He Ping Luo Shi-ren Sun Ji-feng Sun Ai-ping Yin Geng-ru Jiang Hong-yu Chen Wen-hu Liu Hong-li Lin Meng Liang Lu Ma Ming Chen Li-qun Song Jian Chen Qing Zhu Chang-ying Xing Yun Li Ji-ning Gao Rong-shan Li Ying Li Hao Zhang Ying Lu Qiao-ling Zhou Jun-zhou Fu Qiang He Guang-yan Cai Xiang-mei Chen 《Journal of Integrative Medicine》 SCIE CAS CSCD 2021年第2期111-119,共9页
Background:Shenyankangfu Tablet(SYKFT)is a Chinese patent medicine that has been used widely to decrease proteinuria and the progression of chronic kidney disease.Objective:This trial compared the efficacy and safety ... Background:Shenyankangfu Tablet(SYKFT)is a Chinese patent medicine that has been used widely to decrease proteinuria and the progression of chronic kidney disease.Objective:This trial compared the efficacy and safety of SYKFT,for the control of proteinuria in primary glomerulonephritis patients,against the standard drug,losartan potassium.Design,setting,participants and intervention:This was a multicenter,double-blind,randomized,controlled clinical trial.Primary glomerulonephritis patients,aged 18-70 years,with blood pressure≤140/90 mmHg,estimated glomerular filtration rate(eGFR)>45 mL/min per 1.73 ㎡,and 24-hour proteinuria level of 0.5-3.0 g,were recruited in 41 hospitals across 19 provinces in China and were randomly divided into five groups:SYKFT,losartan potassium 50 mg or 100 mg,SYKFT plus losartan potassium 50 mg or 100 mg.Main outcome measu res:The primary outcome was change in the 24-hour proteinuria level,after 48 weeks of treatment.Results:A total of 735 participants were enrolled.The percent decline of urine protein quantification in the SYKFT group after 48 weeks was 8.78%±2.56%(P=0.006)more than that in the losartan 50 mg group,which was 0.51%±2.54%(P=1.000)less than that in the losartan 100 mg group.Compared with the losartan potassium 50 mg group,the SYKFT plus losartan potassium 50 mg group had a 13.39%±2.49%(P<0.001)greater reduction in urine protein level.Compared with the losartan potassium 100 mg group,the SYKFT plus losartan potassium 100 mg group had a 9.77%±2.52%(P=0.001)greater reduction in urine protein.With a superiority threshold of 15%,neither was statistically significant.eGFR,serum creatinine and serum albumin from the baseline did not change statistically significant.The average change in TCM syndrome score between the patients who took SYKFT(-3.00[-6.00,-2.00])and who did not take SYKFT(-2.00[-5.00,0])was statistically significant(P=0.003).No obvious adverse reactions were observed in any group.Conclusion:SYKFT decreased the proteinuria and improved the TCM syndrome scores of primary glomerulonephritis patients,with no change in the rate of decrease in the eGFR.SYKFT plus losartan potassium therapy decreased proteinuria more than losartan potassium therapy alone.Trial registration number:NCT02063100 on ClinicalTrials.gov. 展开更多
关键词 Herbal medicine Chinese Shenyankangfu Tablet Primary glomerulonephritis Randomized controlled trial Double blind Double dummy
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Effect coding与dummy coding赋值方法及其医学研究应用
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作者 高俊宏 董丽芳 +1 位作者 颜虹 王多劳 《中国卫生统计》 CSCD 北大核心 2013年第2期302-303,306,共3页
目的介绍effect coding的变量赋值方法及其在医学研究中的应用,并与dummy coding方法比较。方法将2005年调查中搜集到西部10省40个县的村医20125张处方作为分析资料,省作为分类变量,分别采用dummy coding与effect coding两种编码方式纳... 目的介绍effect coding的变量赋值方法及其在医学研究中的应用,并与dummy coding方法比较。方法将2005年调查中搜集到西部10省40个县的村医20125张处方作为分析资料,省作为分类变量,分别采用dummy coding与effect coding两种编码方式纳入模型,分析处方费用的影响因素,并做比较。结果分类变量的编码方式不同,不会影响回归分析的结果。疾病种类、村医的文化程度、患者年龄、在治疗中是否使用注射剂以及处方所开出的药物个数都是村医处方费用的影响因素。结论 Effect coding在回归的系数的解释方面有其独到的优点,各省份的回归系数之间可以直接进行大小的比较,回归系数的正负表示该省的处方费用较平均水平的高低。 展开更多
关键词 EFFECT CODING DUMMY coding处方费用
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形式动词的次分类 被引量:32
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作者 周刚 《汉语学习》 1987年第1期11-14,共4页
1.1 现代汉语有一类动词,常见的是“加以、给以、予以、给予、进行、作”等,这类动词能够带一个动词组成述宾结构,表示对人或事物处置和对待,其本身却不表示具体的动作行为意义,只充当形式上的述语,而让后边动词宾语来负载这个述宾结构... 1.1 现代汉语有一类动词,常见的是“加以、给以、予以、给予、进行、作”等,这类动词能够带一个动词组成述宾结构,表示对人或事物处置和对待,其本身却不表示具体的动作行为意义,只充当形式上的述语,而让后边动词宾语来负载这个述宾结构的语义信息。我们把这类动词叫做形式动词(dummy verb,以下标记为DV)。 1.2 DV可以分为两个次类: DVa 加以 给以 予以 给予 DVb 进行 作 分类的依据如下。 2.1 在语义上,DVa表示施加义和授予义,具有短时完成、非持续、无过程的时间和要求受事的空间特征。例如: (1)对重要的问题要加以论证。(《邓小平文选》) (2)共产党员要对这种不正之风予以抵制。 (3)对实行计划生育的,要给予优待。(《周恩来选集》下卷) 因此DVa的语义特征可以记作[+完成]、[—持续],[—过程]、[+要求受事]。 DVb表示从事义和举行义,具有非短时完成、可持续、有过程的时间特征。在空间特征上,DVb有时要求受事,有时不要求受事。例如: 展开更多
关键词 形式动词 次分类 扩展形式 定语 述宾结构 动词宾语 DUMMY 事义 动词组 动态助词
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Underwater explosion effects of 60 mm H.E. mortar bomb on a cylindrical concrete structure-PIT 被引量:3
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作者 Faruk Razic Burek Miralem 《Defence Technology(防务技术)》 SCIE EI CAS CSCD 2019年第1期65-71,共7页
PIT tests are usually performed when a mass distribution of High Explosive(H.E) projectile fragments is required. This paper shows the underwater detonation effects of 60 mm, M90 H.E. mortar bomb filled with Comp. B o... PIT tests are usually performed when a mass distribution of High Explosive(H.E) projectile fragments is required. This paper shows the underwater detonation effects of 60 mm, M90 H.E. mortar bomb filled with Comp. B on cylindrical concrete structure(concrete pipe closed at one end-similar to a PIT test)which is 2 m high(inner height) with inner diameter of also 2 m. Thickness of both wall and bottom of a pipe is 0.35 m. Detailed characteristics of concrete which is used for manufacturing of a pipe are specified. Mortar bomb is submerged directly in to the water(no free airspace around the bomb) with the nose pointing to the bottom of a pipe. Number and mass of fragments after detonation are presented by table and photographs. Fragments of dummy fuze, through which blasting cap was protruded, are collected and reassembled to form a shape of a fuze after detonation where expanding of fuze material due to a detonation products is visualized. After underwater detonation, detonation of the same mortar bomb is performed in an empty pipe and the effects of this kind of detonation are observed. Distance at which fragments generated from submerged mortar bomb will not reach concrete pipes wall is also determined. 展开更多
关键词 Underwater explosion MORTAR BOMB Blast Comp B DUMMY FUZE FRAGMENTS
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Investigations of the mechanical response of dummy HTPB propellant grain under ultrahigh acceleration overload conditions using onboard flight-test measurements 被引量:4
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作者 Yiming Zhang Ningfei Wang +3 位作者 Weihua Ma Ran Wang Long Bai Yi Wu 《Defence Technology(防务技术)》 SCIE EI CAS CSCD 2024年第2期473-484,共12页
In this paper,to study the mechanical responses of a solid propellant subjected to ultrahigh acceleration overload during the gun-launch process,specifically designed projectile flight tests with an onboard measuremen... In this paper,to study the mechanical responses of a solid propellant subjected to ultrahigh acceleration overload during the gun-launch process,specifically designed projectile flight tests with an onboard measurement system were performed.Two projectiles containing dummy HTPB propellant grains were successfully recovered after the flight tests with an ultrahigh acceleration overload value of 8100 g.The onboard-measured time-resolved axial displacement,contact stress and overload values were successfully obtained and analysed.Uniaxial compression tests of the dummy HTPB propellant used in the gunlaunched tests were carried out at low and intermediate strain rates to characterize the propellant's dynamic properties.A linear viscoelastic constitutive model was employed and applied in finite-element simulations of the projectile-launching process.During the launch process,the dummy propellant grain exhibited large deformation due to the high acceleration overload,possibly leading to friction between the motor case and propellant grain.The calculated contact stress showed good agreement with the experimental results,though discrepancies in the overall displacement of the dummy propellant grain were observed.The dynamic mechanical response process of the dummy propellant grain was analysed in detail.The results can be used to estimate the structural integrity of the analysed dummy propellant grain during the gun-launch process. 展开更多
关键词 Gun-launched flight test Dummy HTPB propellant Onboard measurements Utrahigh overload Mechanical response
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Influence of platform position on stray grain nucleation in Ni-based single-crystal dummy blade clusters 被引量:2
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作者 Zhen-yu Yang Chen-guang Liu +3 位作者 Song-song Hu Su-jie Zheng Yu-shi Luo Shen-long Dai 《China Foundry》 SCIE CAS 2021年第5期442-449,共8页
Stray grains are the most severe of the solidification defects that occur in the industrial single-crystal blade preparation process.In this study,a single-crystal dummy blade cluster with different crystal orientatio... Stray grains are the most severe of the solidification defects that occur in the industrial single-crystal blade preparation process.In this study,a single-crystal dummy blade cluster with different crystal orientations controlled by the seeding method was prepared,and the influence of the position of the circular platform(relative to the sample and furnace body)on stray grain nucleation was investigated.Results show that the microstructure of the circular platforms could be divided into the center,expansion,and stray grain regions.The inside of the circular platform facing the center of the cluster is more prone to stray grain formation than the outside of the circular platform facing the furnace body.With an increase in the distance between the circular platform and the bottom of the dummy blade cluster,the stray grain region expands,whereas the expansion region narrows.The stray grain is slightly aggravated with increase of the misorientation.Finally,the mechanism underlying the influence of platform position on the formation of stray grains in single-crystal dummy blade clusters is discussed based on the temperature evolution during directional solidification. 展开更多
关键词 Ni-based single-crystal superalloy directional solidification stray grain NUCLEATION dummy blade cluster
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