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Weaknesses of Chomsky's Theory of Language
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作者 鲍志坤 《海外英语》 2013年第13期1-3,共3页
As seemingly persuasive as Chomsky's theory is, it is significantly flawed in four aspects: 1. ignoring a much fundamental creative force in early infancy; 2. equation of first-language learning with second-langua... As seemingly persuasive as Chomsky's theory is, it is significantly flawed in four aspects: 1. ignoring a much fundamental creative force in early infancy; 2. equation of first-language learning with second-language learning; 3. methodology; 4. employment of terms. 展开更多
关键词 weaknesses Chomsky’s THEORY of LANGUAGE
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Strengths, weaknesses, opportunities and threats (SWOT) analysis of reinitiation into methamphetamine abusers: qualitative findings from an exploration of methamphetamine abusers in Shanghai, China 被引量:10
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作者 Youwei Zhu Na Zhong +8 位作者 Hang Su Xiaolu Ruan Jiayi Bao Lei Zhang Jiang Du Ding Xu Rongjie Ding Ke Xiao Min Zhao 《General Psychiatry》 CSCD 2019年第3期137-145,共9页
Background Despite high relapse rate among methamphetamine (MA) abusers, there still have been little empirical data to date detecting the risk factors related to craving and relapse from the perspective of MA abusers... Background Despite high relapse rate among methamphetamine (MA) abusers, there still have been little empirical data to date detecting the risk factors related to craving and relapse from the perspective of MA abusers. Therefore, the aim of this study was to use qualitative research methods exploring the strengths, weaknesses, opportunities and threat factors that could facilitate or impede individuals' abstinence in a real-life context from the perspectives of MA abusers. Aim To use qualitative research methods exploring the strengths, weaknesses, opportunities and threat factors relating to individuals' abstinence in a real-life context. Method Semistructured interviews were conducted with 32 MA abusers recruited in Shanghai guided by open-ended questions on narrating the real-life catalysts and inhibitors related to craving, initiation, relapse and abstinence. All data were transcribed verbatim and analysed using a strengths, weaknesses, opportunities and threats (SWOT) analysis. Results The results of the SWOT analysis revealed that contextual factors including peer influence, prevalence and availability of MA, familiar venue of MA use, discrimination, sexual behaviours, alcohol, emotional states and their attitudes towards smoking MA were important factors that contribute to reinitiation and relapse. Surveillance systems, antidrug social workers, vocational skills trainings, moving to another city and family responsibility might serve as counter measures targeti叩 those mentioned weaknesses and threats above. Conclusion This SWOT analysis highlights the complex nature of relapse. Comprehensive interventions strengtheni叩 coping skills such as virtual reality techniques are desperately needed to facilitate individuals1 sustained abstinence. 展开更多
关键词 Strengths weaknesses OPPORTUNITIES
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The Strengths and Weaknesses of Mini-Class Model for Chinese College Students
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作者 Qu Ying 《Sino-US English Teaching》 2012年第7期1306-1311,共6页
When it comes to the practical use of English, the traditional college English class, which has big size and uses lecture-style teaching, has increasingly showed its disadvantages. The English Department of Harbin Eng... When it comes to the practical use of English, the traditional college English class, which has big size and uses lecture-style teaching, has increasingly showed its disadvantages. The English Department of Harbin Engineering University has initiated a mini-class model in recent years, which has received positive responses from both teachers and students who have experienced the class. By comparing the lecture-style class with mini-class, this paper will introduce the strengths and weaknesses of mini-class according to the author's observation of the class as well as the feedbacks from teachers and students. As is found out, its strengths far outweigh its weaknesses, and therefore the model is highly recommended for college English class in other schools 展开更多
关键词 strengths weaknesses mini-class model
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CHINA-U.S. COMPETITION ON KOREAN PENINSULA-ADVANTAGES AND WEAKNESSES
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作者 DONG XIANGRONG 《Contemporary World》 2017年第2期26-29,共4页
America is the only hegemonic power in the world today and is looking vigilantly at every other country that may take its hegemonic position.In Northeast Asia,America is focused on reinforcing its alliance with Japan ... America is the only hegemonic power in the world today and is looking vigilantly at every other country that may take its hegemonic position.In Northeast Asia,America is focused on reinforcing its alliance with Japan and South Korea and is working quickly to deploy the THAAD system in 展开更多
关键词 into with on of that IS COMPETITION ON KOREAN PENINSULA-ADVANTAGES AND weaknesses CHINA-U.S HAVE for THAN from
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Analysis of Strengths,Weaknesses,Opportunities,and Threats on the Development and Internationalization of China’s Vocational Education in the Context of“The Belt and Road Initiative”Strategy
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作者 Na Hu Hua Xie 《Journal of Contemporary Educational Research》 2019年第2期18-23,共6页
The belt and road initiative strategy is proposed based on the stable and sustainable cooperation on economy and development between China and neighboring countries.The development of economy can affect every aspect o... The belt and road initiative strategy is proposed based on the stable and sustainable cooperation on economy and development between China and neighboring countries.The development of economy can affect every aspect of vocational education development.Therefore,vocational education in China must be moved toward internationalization to achieve sustainable development in the face of the implementation of the belt and road initiative strategy.The analysis data obtained through the strengths,weaknesses,opportunities,and threats analysis method on the internationalization of China’s vocational education under the background of the belt and road initiative strategy were the advantages analysis(strengths)of continuous maturity in developing of vocational education,which drives by economic development and the foreign employment and entrepreneurship guidance mechanism;the disadvantages analysis(weaknesses)of lack talent cultivation and weak branding of vocational education;analysis of support opportunities given by national policy;and threats analysis of social culture in the involved countries along the route.To further develop and expand China’s vocational education under the background of the belt and road initiative strategy,some countermeasures were proposed such as improves cultivation or training of talents,to build strong branding of China vocational education,and faces cultural challenges to facilitate the international development of China vocational education. 展开更多
关键词 strengths weaknesses opportunities and threats ANALYSIS method the BELT and ROAD initiative vocational education INTERNATIONALIZATION
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Strengths,Weaknesses,Opportunities,and Threats Analysis and Countermeasures on the Cultivation of Preschool Teachers in Sichuan Province
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作者 Fei Liu Yingying Wang 《Journal of Contemporary Educational Research》 2019年第2期40-45,共6页
Training of preschool teachers in Sichuan Province brings advantages in increasing government support for the preschool education industry.The society attaches an important role to the preschool education industry as ... Training of preschool teachers in Sichuan Province brings advantages in increasing government support for the preschool education industry.The society attaches an important role to the preschool education industry as well as the rapid development of preschool education in Sichuan Province.However,problem exists in large flows of preschool teachers and imbalanced gender ratios.By viewing from the new situation,the comprehensive liberalization of the second-child policy and the development of educational informatization as well as the implementation of the one belt and one road strategy have created great opportunities in training of preschool teachers.At the same time,the increase in external impact of high-quality graduates in the east also poses a great threat to the development of preschool teachers in Sichuan Province.Through the strategic combination of strengths,weaknesses,opportunities,and threats analysis,the paper explores effective countermeasure ways to improve the quality of training of the preschool teachers in Sichuan Province and the construction of an excellent team of preschool teachers in Sichuan Province. 展开更多
关键词 early CHILDHOOD education strengths weaknesses opportunities and threats ANALYSIS TEACHER training
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Study on Human Weaknesses in Henry in The Red Badge of Courage
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作者 CHU Shi-qi 《Journal of Literature and Art Studies》 2022年第12期1257-1260,共4页
As one of Crane’s most representative works,The Red Badge of Courage has been paid much attention to and studied by scholars at home and abroad from different perspectives since its publication.As for me,I’d like to... As one of Crane’s most representative works,The Red Badge of Courage has been paid much attention to and studied by scholars at home and abroad from different perspectives since its publication.As for me,I’d like to study on human weaknesses in Henry in The Red Badge of Courage to give an analysis of the three main human weaknesses existing in Henry and explore the underlying causes.It will be of great benefit to promote our understanding of the novel from this angle,thus bringing us much practical significance. 展开更多
关键词 The Red Badge of Courage human weaknesses Henry
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An Analysis on the Strengths and Weaknesses of Edward Said's theory of Orientalism
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作者 乐冰洁 《海外英语》 2015年第10期173-175,共3页
In Orientalism,the author Edward W.Said stated that the Orient is negatively defined and serves to support the West'ssuperiority and strength.Citing a number of discourses and texts in the book,he broke the bounda... In Orientalism,the author Edward W.Said stated that the Orient is negatively defined and serves to support the West'ssuperiority and strength.Citing a number of discourses and texts in the book,he broke the boundary between knowledge and poli-tics,and further examined how the knowledge that the Western colonial powers shaped about the Orient assisted to make a de-praved picture of the colonies,to justify their colonial ambition and suppression.Nevertheless,although Said attempted to explainthe selection of the oriental area in his discussion,a vast area of the Far East,such as China and Japan is excluded.Furthermore,he regarded the Orient as a completely passive colony,and negated any resistance from the Orient. 展开更多
关键词 EDWARD SAID ORIENTALISM STRENGTH WEAKNESS postcolonial studies
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Overview of Strengths and Weaknesses of Native and Non-native English Speaking Teachers
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作者 刘洁 《海外英语》 2018年第19期266-268,共3页
More and more non-native English speaking teachers teach with native English speaking teachers in Chinese context or other non-English speaking countries. It is worthwhile to evaluate their strengths and constraints. ... More and more non-native English speaking teachers teach with native English speaking teachers in Chinese context or other non-English speaking countries. It is worthwhile to evaluate their strengths and constraints. The current paper discusses their differences in term of linguistic teaching characteristics, social culture teaching characteristics and pedagogical teaching characteristics. It concludes that two groups of teachers can be successful language teachers with the equal chances on their own terms and can make up for their constraints by applying certain patterns of collaboration. 展开更多
关键词 NESTS NNESTs teaching characteristics strength WEAKNESS
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Significant risk factors for intensive care unit-acquired weakness:A processing strategy based on repeated machine learning 被引量:9
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作者 Ling Wang Deng-Yan Long 《World Journal of Clinical Cases》 SCIE 2024年第7期1235-1242,共8页
BACKGROUND Intensive care unit-acquired weakness(ICU-AW)is a common complication that significantly impacts the patient's recovery process,even leading to adverse outcomes.Currently,there is a lack of effective pr... BACKGROUND Intensive care unit-acquired weakness(ICU-AW)is a common complication that significantly impacts the patient's recovery process,even leading to adverse outcomes.Currently,there is a lack of effective preventive measures.AIM To identify significant risk factors for ICU-AW through iterative machine learning techniques and offer recommendations for its prevention and treatment.METHODS Patients were categorized into ICU-AW and non-ICU-AW groups on the 14th day post-ICU admission.Relevant data from the initial 14 d of ICU stay,such as age,comorbidities,sedative dosage,vasopressor dosage,duration of mechanical ventilation,length of ICU stay,and rehabilitation therapy,were gathered.The relationships between these variables and ICU-AW were examined.Utilizing iterative machine learning techniques,a multilayer perceptron neural network model was developed,and its predictive performance for ICU-AW was assessed using the receiver operating characteristic curve.RESULTS Within the ICU-AW group,age,duration of mechanical ventilation,lorazepam dosage,adrenaline dosage,and length of ICU stay were significantly higher than in the non-ICU-AW group.Additionally,sepsis,multiple organ dysfunction syndrome,hypoalbuminemia,acute heart failure,respiratory failure,acute kidney injury,anemia,stress-related gastrointestinal bleeding,shock,hypertension,coronary artery disease,malignant tumors,and rehabilitation therapy ratios were significantly higher in the ICU-AW group,demonstrating statistical significance.The most influential factors contributing to ICU-AW were identified as the length of ICU stay(100.0%)and the duration of mechanical ventilation(54.9%).The neural network model predicted ICU-AW with an area under the curve of 0.941,sensitivity of 92.2%,and specificity of 82.7%.CONCLUSION The main factors influencing ICU-AW are the length of ICU stay and the duration of mechanical ventilation.A primary preventive strategy,when feasible,involves minimizing both ICU stay and mechanical ventilation duration. 展开更多
关键词 Intensive care unit-acquired weakness Risk factors Machine learning PREVENTION Strategies
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Numerical and experimental investigation on hydraulic-electric rock fragmentation of heterogeneous granite 被引量:1
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作者 Xiaohua Zhu Ling He +3 位作者 Weiji Liu Yunxu Luo Youjian Zhang Wuji Tang 《International Journal of Mining Science and Technology》 SCIE EI CAS CSCD 2024年第1期15-29,共15页
Hydraulic-electric rock fragmentation(HERF)plays a significant role in improving the efficiency of high voltage pulse rock breaking.However,the underlying mechanism of HERF remains unclear.In this study,considering th... Hydraulic-electric rock fragmentation(HERF)plays a significant role in improving the efficiency of high voltage pulse rock breaking.However,the underlying mechanism of HERF remains unclear.In this study,considering the heterogeneity of the rock,microscopic thermodynamic properties,and shockwave time domain waveforms,based on the shockwave model,digital imaging technology and the discrete element method,the cyclic loading numerical simulations of HERF is achieved by coupling electrical,thermal,and solid mechanics under different formation temperatures,confining pressure,initial peak voltage,electrode bit diameter,and loading times.Meanwhile,the HERF discharge system is conducive to the laboratory experiments with various electrical parameters and the resulting broken pits are numerically reconstructed to obtain the geometric parameters.The results show that,the completely broken area consists of powdery rock debris.In the pre-broken zone,the mineral cementation of the rock determines the transition of type CⅠcracks to type CⅡand type CⅢcracks.Furthermore,the peak pressure of the shockwave increased with initial peak voltage but decreased with electrode bit diameter,while the wave front time reduced.Moreover,increasing well depth,formation temperature and confining pressure augment and inhibit HERF,but once confining pressure surpassed the threshold of 60 MPa for 152.40,215.90,and 228.60 mm electrode bits,and 40 MPa for 309.88 mm electrode bits,HERF is promoted.Additionally,for the same kind of rock,the volume and width of the broken pit increase with higher initial peak voltage and rock fissures will promote HERF.Eventually,the electrode drill bit with a 215.90 mm diameter is more suitable for drilling pink granite.This research contributes to a better microscopic understanding of HERF and provides valuable insights for electrode bit selection,as well as the optimization of circuit parameters for HERF technology. 展开更多
关键词 Hydraulic-electric rock fragmentation SHOCKWAVE Thermodynamics MICROCRACKS Weak Linear Parallel Bond Model
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A robust & weak-nucleophilicity electrocatalyst with an inert response for chlorine ion oxidation in large-current seawater electrolysis 被引量:1
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作者 Junting Dong Chang Yu +5 位作者 Hui Wang Lin Chen Hongling Huang Yingnan Han Qianbing Wei Jieshan Qiu 《Journal of Energy Chemistry》 SCIE EI CAS CSCD 2024年第3期486-495,I0011,共11页
Seawater splitting into hydrogen,a promising technology,is seriously limited by the durability and tolerance of electrocatalysts for chlorine ions in seawater at large current densities due to chloride oxidation and c... Seawater splitting into hydrogen,a promising technology,is seriously limited by the durability and tolerance of electrocatalysts for chlorine ions in seawater at large current densities due to chloride oxidation and corrosion.Here,we present a robust and weak-nucleophilicity nickel-iron hydroxide electrocatalyst with excellent selectivity for oxygen evolution and an inert response for chlorine ion oxidation which are key and highly desired for efficient seawater electrolysis.Such a weak-nucleophilicity electrocatalyst can well match with strong-nucleophilicity OH-compared with the weak-nucleophilicity Cl^(-),resultantly,the oxidation of OH-in electrolyte can be more easily achieved relative to chlorine ion oxidation,confirmed by ethylenediaminetetraacetic acid disodium probing test.Further,no strongly corrosive hypochlorite is produced when the operating voltage reaches about 2.1 V vs.RHE,a potential that is far beyond the thermodynamic potential of chlorine ion oxidatio n.This concept and approach to reasonably designing weaknucleophilicity electrocatalysts that can greatly avoid chlorine ion oxidation under alkaline seawater environments can push forward the seawater electrolysis technology and also accelerate the development of green hydrogen technique. 展开更多
关键词 Nickel-iron hydroxide electrocatalysts Highly selective seawater electrolysis Weak nucleophilicity Oxygen evolution reaction Hydrogen
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Study on the low mechanical anisotropy of extruded Mg-Zn-Mn-Ce-Ca alloy tube in the compression process 被引量:1
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作者 Dandan Li Qichi Le +6 位作者 Xiong Zhou Xiaoqiang Li Chenglu Hu Ruizhen Guo Tong Wang Ping Wang Wenxin Hu 《Journal of Magnesium and Alloys》 SCIE EI CAS CSCD 2024年第3期1054-1067,共14页
In this study,the extruded Mg-Zn-Mn-Ce-Ca alloy tube with a low compression anisotropy along the ED,45ED and TD was prepared.The effect of the second phases,initial texture and deformation behavior on this low mechani... In this study,the extruded Mg-Zn-Mn-Ce-Ca alloy tube with a low compression anisotropy along the ED,45ED and TD was prepared.The effect of the second phases,initial texture and deformation behavior on this low mechanical anisotropy was investigated.The results revealed that the alloy tube contains the high content(Mg1-xZnx)11Ce phase and the low content of Mg12Ce phase.These second phases are respectively incoherent and coherent with the Mg matrix,and their influence can be ignored.Additionally,the alloy tube exhibited a weak basal fiber texture,where the c-axis was aligned along the 0°∼30°tilt from TD to ED.Such a texture made the initial deformation(at 1.0%∼1.6%strain)of the three samples controlled by comparable basalslip.As deformation progressed(1.6∼9.0%strain),larger amounts of ETWs nucleated and gradually approached saturation in the three samples,re-orienting the c-axis to a 0°∼±30°deviation with respect to the loading directions.Meanwhile,the prismatic and pyramidal<c+a>slips replaced the dominant deformation progressively until fracture.Eventually,the similar deformation mechanisms determined by the weak initial texture in the three samples contribute to the comparable strain hardening rates,resulting in the low compressive anisotropy of the alloy tube. 展开更多
关键词 Mg alloy tube Low mechanical anisotropy Weak texture Deformation mechanism.
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THREE KINDS OF DENTABILITIES IN BANACH SPACES AND THEIR APPLICATIONS
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作者 张子厚 周晶 《Acta Mathematica Scientia》 SCIE CSCD 2024年第2期445-454,共10页
In this paper,we study some dentabilities in Banach spaces which are closely related to the famous Radon-Nikodym property.We introduce the concepts of the weak^(*)-weak denting point and the weak^(*)-weak^(*)denting p... In this paper,we study some dentabilities in Banach spaces which are closely related to the famous Radon-Nikodym property.We introduce the concepts of the weak^(*)-weak denting point and the weak^(*)-weak^(*)denting point of a set.These are the generalizations of the weak^(*)denting point of a set in a dual Banach space.By use of the weak^(*)-weak denting point,we characterize the very smooth space,the point of weak^(*)-weak continuity,and the extreme point of a unit ball in a dual Banach space.Meanwhile,we also characterize an approximatively weak compact Chebyshev set in dual Banach spaces.Moreover,we define the nearly weak dentability in Banach spaces,which is a generalization of near dentability.We prove the necessary and sufficient conditions of the reflexivity by nearly weak dentability.We also obtain that nearly weak dentability is equivalent to both the approximatively weak compactness of Banach spaces and the w-strong proximinality of every closed convex subset of Banach spaces. 展开更多
关键词 weak^(*)-weak denting point nearly weak dentability very smooth space point of weak^(*)-weak continuity extreme point approximatively weak compactness w-strong proximinality REFLEXIVITY
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GLOBAL WEAK SOLUTIONS FOR AN ATTRACTION-REPULSION CHEMOTAXIS SYSTEM WITH p-LAPLACIAN DIFFUSION AND LOGISTIC SOURCE
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作者 王晓闪 王忠谦 贾哲 《Acta Mathematica Scientia》 SCIE CSCD 2024年第3期909-924,共16页
This paper is concerned with the following attraction-repulsion chemotaxis system with p-Laplacian diffusion and logistic source:■The system here is under a homogenous Neumann boundary condition in a bounded domainΩ... This paper is concerned with the following attraction-repulsion chemotaxis system with p-Laplacian diffusion and logistic source:■The system here is under a homogenous Neumann boundary condition in a bounded domainΩ ■ R^(n)(n≥2),with χ,ξ,α,β,γ,δ,k_(1),k_(2)> 0,p> 2.In addition,the function f is smooth and satisfies that f(s)≤κ-μs~l for all s≥0,with κ ∈ R,μ> 0,l> 1.It is shown that(ⅰ)if l> max{2k_(1),(2k_(1)n)/(2+n)+1/(p-1)},then system possesses a global bounded weak solution and(ⅱ)if k_(2)> max{2k_(1)-1,(2k_(1)n)/(2+n)+(2-p)/(p-1)} with l> 2,then system possesses a global bounded weak solution. 展开更多
关键词 global weak solutions attraction-repulsion P-LAPLACIAN logistic source
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Experimental investigation on weak shock wave mitigation characteristics of flexible polyurethane foam and polyurea
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作者 Shiyu Jia Cheng Wang +2 位作者 Wenlong Xu Dong Ma Fangfang Qi 《Defence Technology(防务技术)》 SCIE EI CAS CSCD 2024年第1期179-191,共13页
In recent years,explosion shock wave has been considered as a signature injury of the current military conflicts.Although strong shock wave is lethal to the human body,weak shock wave can cause many more lasting conse... In recent years,explosion shock wave has been considered as a signature injury of the current military conflicts.Although strong shock wave is lethal to the human body,weak shock wave can cause many more lasting consequences.To investigate the protection ability and characteristics of flexible materials and structures under weak shock wave loading,the blast wave produced by TNT explosive is loaded on the polyurethane foam with the density of 200.0 kg/m3(F-200)and 400.0 kg/m3(F-400),polyurea with the density of 1100.0 kg/m^(3)(P-1100)and structures composed of the two materials,which are intended for individual protection.Experimental results indicate that the shock wave is attenuated to weak pressure disturbance after interacting with the flexible materials which are not damaged.The shock wave protective capability of single-layer materials is dependent on their thickness,density and microscopic characteristics.The overpressure,maximum pressure rise rate and impulse of transmitted wave decrease exponentially with increase in sample thickness.For the same thickness,F-400 provides better protective capability than F-200 while P-1100 shows the best protective capability among the three materials.In this study,as the materials are not destroyed,F-200 with a thickness more than10.0 mm,F-400 with a thickness more than 4.0 mm,and P-1100 with a thickness more than 1.0 mm can attenuate the overpressure amplitude more than 90.0%.Further,multi-layer flexible composites are designed.Different layer layouts of designed structures and layer thickness of the single-layer materials can affect the protective performance.Within the research range,the structure in which polyurea is placed on the impact side shows the optimal shock wave protective performance,and the thicknesses of polyurea and polyurethane foam are 1.0 mm and 4.0 mm respectively.The overpressure attenuation rate reached maximum value of 93.3%and impulse attenuation capacity of this structure are better than those of single-layer polyurea and polyurethane foam with higher areal density. 展开更多
关键词 Free-field explosion Weak shock wave mitigation POLYUREA Polyurethane foam Multi-layered composites
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Negative Stiffness Mechanism on An Asymmetric Wave Energy Converter by Using A Weakly Nonlinear Potential Model
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作者 Sunny Kumar POGULURI Dongeun KIM Yoon Hyeok BAE 《China Ocean Engineering》 SCIE EI CSCD 2024年第4期689-700,共12页
Salter's duck,an asymmetrical wave energy converter(WEC)device,showed high efficiency in extracting energy from 2D regular waves in the past;yet,challenges remain for fluctuating wave conditions.These can potentia... Salter's duck,an asymmetrical wave energy converter(WEC)device,showed high efficiency in extracting energy from 2D regular waves in the past;yet,challenges remain for fluctuating wave conditions.These can potentially be addressed by adopting a negative stiffness mechanism(NSM)in WEC devices to enhance system efficiency,even in highly nonlinear and steep 3D waves.A weakly nonlinear model was developed which incorporated a nonlinear restoring moment and NSM into the linear formulations and was applied to an asymmetric WEC using a time domain potential flow model.The model was initially validated by comparing it with published experimental and numerical computational fluid dynamics results.The current results were in good agreement with the published results.It was found that the energy extraction increased in the range of 6%to 17%during the evaluation of the effectiveness of the NSM in regular waves.Under irregular wave conditions,specifically at the design wave conditions for the selected test site,the energy extraction increased by 2.4%,with annual energy production increments of approximately 0.8MWh.The findings highlight the potential of NSM in enhancing the performance of asymmetric WEC devices,indicating more efficient energy extraction under various wave conditions. 展开更多
关键词 asymmetric wave energy converter negative stiffness mechanism weakly nonlinear potential flow POWER
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N-th root slant stack for enhancing weak seismic signals
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作者 Li Fei Xie Jun-fa +4 位作者 Yao Zong-hui Li Mei Zhao Yu-lian Liu Wei-ming Chen Juan 《Applied Geophysics》 SCIE CSCD 2024年第3期479-486,617,共9页
Seismic imaging of complicated underground structures with severe surface undulation(i.e.,double complex areas)is challenging owing to the difficulty of collecting the very weak reflected signal.Enhancing the weak sig... Seismic imaging of complicated underground structures with severe surface undulation(i.e.,double complex areas)is challenging owing to the difficulty of collecting the very weak reflected signal.Enhancing the weak signal is difficult even with state-of-the-art multi-domain and multidimensional prestack denoising techniques.This paper presents a time–space dip analysis of offset vector tile(OVT)domain data based on theτ-p transform.The proposed N-th root slant stack method enhances the signal in a three-dimensionalτ-p domain by establishing a zero-offset time-dip seismic attribute trace and calculating the coherence values of a given data sub-volume(i.e.,inline,crossline,time),which are then used to recalculate the data.After sorting,the new data provide a solid foundation for obtaining the optimal N value of the N-th root slant stack,which is used to enhance a weak signal.The proposed method was applied to denoising low signal-to-noise ratio(SNR)data from Western China.The optimal N value was determined for improving the SNR in deep strata,and the weak seismic signal was enhanced.The results showed that the proposed method effectively suppressed noise in low-SNR data. 展开更多
关键词 N-th root Weak seismic signal τ-p OVT
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Ultrahigh-brightness 50 MeV electron beam generation from laser wakefield acceleration in a weakly nonlinear regime
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作者 Zhongtao Xiang Changhai Yu +8 位作者 Zhiyong Qin Xuhui Jiao Jiahui Cheng Qiaoxuan Zhou Gatie Axi Jianghua Jie Ya Huang Jintan Cai Jiansheng Liu 《Matter and Radiation at Extremes》 SCIE EI CSCD 2024年第3期4-10,共7页
We propose an efficient scheme to produce ultrahigh-brightness tens of MeV electron beams by designing a density-tailored plasma to induce a wakefield in the weakly nonlinear regime with a moderate laser energy of 120... We propose an efficient scheme to produce ultrahigh-brightness tens of MeV electron beams by designing a density-tailored plasma to induce a wakefield in the weakly nonlinear regime with a moderate laser energy of 120 mJ.In this scheme,the second bucket of the wakefield can have a much lower phase velocity at the steep plasma density down-ramp than the first bucket and can be exploited to implement longitudinal electron injection at a lower laser intensity,leading to the generation of bright electron beams with ultralow emittance together with low energy spread.Three-dimensional particle-in-cell simulations are carried out and demonstrate that high-quality electron beams with a peak energy of 50 MeV,ultralow emittance of28 nm rad,energy spread of 1%,charge of 4.4 pC,and short duration less than 5 fs can be obtained within a 1-mm-long tailored plasma density,resulting in an ultrahigh six-dimensional brightness B6D,n of2×1017 A/m2/0.1%.By changing the density parameters,tunable bright electron beams with peak energies ranging from 5 to 70 MeV,a small emittance of B0.1 mm mrad,and a low energy spread at a few-percent level can be obtained.These bright MeV-class electron beams have a variety of potential applications,for example,as ultrafast electron probes for diffraction and imaging,in laboratory astrophysics,in coherent radiation source generation,and as injectors for GeV particle accelerators. 展开更多
关键词 WEAKLY nonlinear ACCELERATION
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Measuring small longitudinal phase shifts via weak measurement amplification
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作者 徐凯 胡晓敏 +7 位作者 胡孟军 王宁宁 张超 黄运锋 柳必恒 李传锋 郭光灿 张永生 《Chinese Physics B》 SCIE EI CAS CSCD 2024年第3期105-111,共7页
Weak measurement amplification,which is considered as a very promising scheme in precision measurement,has been applied to various small physical quantities estimations.Since many physical quantities can be converted ... Weak measurement amplification,which is considered as a very promising scheme in precision measurement,has been applied to various small physical quantities estimations.Since many physical quantities can be converted into phase signals,it is interesting and important to consider measuring small longitudinal phase shifts by using weak measurement.Here,we propose and experimentally demonstrate a novel weak measurement amplification-based small longitudinal phase estimation,which is suitable for polarization interferometry.We realize one order of magnitude amplification measurement of a small phase signal directly introduced by a liquid crystal variable retarder and show that it is robust to the imperfection of interference.Besides,we analyze the effect of magnification error which is never considered in the previous works,and find the constraint on the magnification.Our results may find important applications in high-precision measurements,e.g.,gravitational wave detection. 展开更多
关键词 weak measurement phase estimation quantum optics
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