Flammable ionic liquids exhibit high conductivity and a broad electrochemical window,enabling the generation of combustible gases for combustion via electrochemical decomposition and thermal decomposition.This charact...Flammable ionic liquids exhibit high conductivity and a broad electrochemical window,enabling the generation of combustible gases for combustion via electrochemical decomposition and thermal decomposition.This characteristic holds significant implications in the realm of novel satellite propulsion.Introducing a fraction of the electrical energy into energetic ionic liquid fuels,the thermal decomposition process is facilitated by reducing the apparent activation energy required,and electrical energy can trigger the electrochemical decomposition of ionic liquids,presenting a promising approach to enhance combustion efficiency and energy release.This study applied an external voltage during the thermal decomposition of 1-ethyl-3-methylimidazole nitrate([EMIm]NO_(3)),revealing the effective alteration of the activation energy of[EMIm]NO_(3).The pyrolysis,electrochemical decomposition,and electron assisted enhancement products were identified through Thermogravimetry-Differential scanning calorimetry-Fourier transform infrared-Mass spectrometry(TG-DSC-FTIR-MS)and gas chromatography(GC)analyses,elucidating the degradation mechanism of[EMIm]NO_(3).Furthermore,an external voltage was introduced during the combustion of[EMIm]NO_(3),demonstrating the impact of voltage on the combustion process.展开更多
In this paper,we propose a sub-6GHz channel assisted hybrid beamforming(HBF)for mmWave system under both line-of-sight(LOS)and non-line-of-sight(NLOS)scenarios without mmWave channel estimation.Meanwhile,we resort to ...In this paper,we propose a sub-6GHz channel assisted hybrid beamforming(HBF)for mmWave system under both line-of-sight(LOS)and non-line-of-sight(NLOS)scenarios without mmWave channel estimation.Meanwhile,we resort to the selfsupervised approach to eliminate the need for labels,thus avoiding the accompanied high cost of data collection and annotation.We first construct the dense connection network(DCnet)with three modules:the feature extraction module for extracting channel characteristic from a large amount of channel data,the feature fusion module for combining multidimensional features,and the prediction module for generating the HBF matrices.Next,we establish a lightweight network architecture,named as LDnet,to reduce the number of model parameters and computational complexity.The proposed sub-6GHz assisted approach eliminates mmWave pilot resources compared to the method using mmWave channel information directly.The simulation results indicate that the proposed DCnet and LDnet can achieve the spectral efficiency that is superior to the traditional orthogonal matching pursuit(OMP)algorithm by 13.66% and 10.44% under LOS scenarios and by 32.35% and 27.75% under NLOS scenarios,respectively.Moreover,the LDnet achieves 98.52% reduction in the number of model parameters and 22.93% reduction in computational complexity compared to DCnet.展开更多
Titanium alloy has the advantages of high strength,strong corrosion resistance,excellent high and low temperature mechanical properties,etc.,and is widely used in aerospace,shipbuilding,weapons and equipment,and other...Titanium alloy has the advantages of high strength,strong corrosion resistance,excellent high and low temperature mechanical properties,etc.,and is widely used in aerospace,shipbuilding,weapons and equipment,and other fields.In recent years,with the continuous increase in demand for medium-thick plate titanium alloys,corresponding welding technologies have also continued to develop.Therefore,this article reviews the research progress of deep penetration welding technology for medium-thick plate titanium alloys,mainly covering traditional arc welding,high-energy beam welding,and other welding technologies.Among many methods,narrow gap welding,hybrid welding,and external energy field assistance welding all contribute to improving the welding efficiency and quality of medium-thick plate titanium alloys.Finally,the development trend of deep penetration welding technology for mediumthick plate titanium alloys is prospected.展开更多
During the automated placement process of dry fibers,the positioning and fixation of dry fiber gauze belts are achieved by spraying setting agents.The amount of the setting agent is difficult to control when it is spr...During the automated placement process of dry fibers,the positioning and fixation of dry fiber gauze belts are achieved by spraying setting agents.The amount of the setting agent is difficult to control when it is sprayed manually.Furthermore,it can also affect the permeability of the preform,resin injection and the quality of the vacuum assisted resin infusion(VARI)molding,resulting in a decrease in the mechanical properties of composite materials.This study utilizes dry fiber automated placement equipment and an automated spraying system to manufacture preform structures,followed by VARI process to prepare composite samples with varying setting agent contents.Subsequently,mechanical characterization including interlaminar shear,bending and tensile testing is conducted to investigate the influence of setting agent content on both the manufacturing process and the mechanical properties of composite products.The results show that the interlaminar shear strength,bending strength and tensile strength of the sample gradually decrease with the increase of the content of the setting agent.The optimal setting agent content for automated laying of dry fiber is determined to be 4%-6%,balancing the preformed body’s layup quality and its impact on mechanical properties.Compared with agent-free samples,this range results in reductions of 3% in interlaminar shear strength,9% in bending strength,11% in bending modulus,and 13%-16% in tensile strength.展开更多
A two-stage catalytic membrane reactor(CMR)that couples CO_(2) splitting with methane oxidation reactions was constructed based on an oxygen-permeable perovskite asymmetric membrane.The asymmetric membrane comprises a...A two-stage catalytic membrane reactor(CMR)that couples CO_(2) splitting with methane oxidation reactions was constructed based on an oxygen-permeable perovskite asymmetric membrane.The asymmetric membrane comprises a dense SrFe_(0.9)Ta_(0.1)O_(3-σ)(SFT)separation layer and a porous Sr_(0.9)(Fe_(0.9)Ta_(0.1))_(0.9)Cu_(0.1)O_(3-σ)(SFTC)catalytic layer.In thefirst stage reactor,a CO_(2) splitting reaction(CDS:2CO_(2)→2CO+O_(2))occurs at the SFTC catalytic layer.Subsequently,the O_(2) product is selectively extracted through the SFT separation layer to the permeated side for the methane combustion reaction(MCR),which provides an extremely low oxygen partial pressure to enhance the oxygen extraction.In the second stage,a Sr_(0.9)(Fe_(0.9)Ta_(0.1))_(0.9)Ni_(0.1)O_(3-σ)(SFTN)catalyst is employed to reform the products derived from MCR.The two-stage CMR design results in a remarkable 35.4%CO_(2) conversion for CDS at 900℃.The two-stage CMR was extended to a hollowfiber configuration combining with solar irradiation.The solar-assisted two-stage CMR can operate stably for over 50 h with a high hydrogen yield of 18.1 mL min^(-1) cm^(-2).These results provide a novel strategy for reducing CO_(2) emissions,suggesting potential avenues for the design of the high-performance CMRs and catalysts based on perovskite oxides in the future.展开更多
Intelligent personal assistants play a pivotal role in in-vehicle systems,significantly enhancing life efficiency,driving safety,and decision-making support.In this study,the multi-modal design elements of intelligent...Intelligent personal assistants play a pivotal role in in-vehicle systems,significantly enhancing life efficiency,driving safety,and decision-making support.In this study,the multi-modal design elements of intelligent personal assistants within the context of visual,auditory,and somatosensory interactions with drivers were discussed.Their impact on the driver’s psychological state through various modes such as visual imagery,voice interaction,and gesture interaction were explored.The study also introduced innovative designs for in-vehicle intelligent personal assistants,incorporating design principles such as driver-centricity,prioritizing passenger safety,and utilizing timely feedback as a criterion.Additionally,the study employed design methods like driver behavior research and driving situation analysis to enhance the emotional connection between drivers and their vehicles,ultimately improving driver satisfaction and trust.展开更多
GHz burst-mode femtosecond(fs)laser,which emits a series of pulse trains with extremely short intervals of several hundred picoseconds,provides distinct characteristics in materials processing as compared with the con...GHz burst-mode femtosecond(fs)laser,which emits a series of pulse trains with extremely short intervals of several hundred picoseconds,provides distinct characteristics in materials processing as compared with the conventional irradiation scheme of fs laser(single-pulse mode).In this paper,we take advantage of the moderate pulse interval of 205 ps(4.88 GHz)in the burst pulse for high-quality and high-efficiency micromachining of single crystalline sapphire by laser induced plasma assisted ablation(LIPAA).Specifically,the preceding pulses in the burst generate plasma by ablation of copper placed behind the sapphire substrate,which interacts with the subsequent pulses to induce ablation at the rear surface of sapphire substrates.As a result,not only the ablation quality but also the ablation efficiency and the fabrication resolution are greatly improved compared to the other schemes including single-pulse mode fs laser direct ablation,single-pulse mode fs-LIPAA,and nanosecond-LIPAA.展开更多
Considering the adsorption loss of the hydraulic fracturing assisted oil displacement(HFAD)agent in the matrix,a method is proposed to characterize the dynamic saturation adsorption capacity of the HFAD agent with pre...Considering the adsorption loss of the hydraulic fracturing assisted oil displacement(HFAD)agent in the matrix,a method is proposed to characterize the dynamic saturation adsorption capacity of the HFAD agent with pressure differential and permeability.Coupled with the viscosity-concentration relationship of the HFAD agent,a non-linear seepage model of HFAD was established,taking into account the adsorption effect of high pressure drops,and the influencing factors were analyzed.The findings indicate that the replenishment of formation energy associated with HFAD technology is predominantly influenced by matrix permeability,fracture length and the initial concentration of the HFAD agent.The effect of replenishment of formation energy is positively correlated with matrix permeability and fracture length,and negatively correlated with the initial concentration of the HFAD agent.The initial concentration and injection amount of the high-pressure HFAD agent can enhance the concentration of the HFAD agent in the matrix and improve the efficiency of oil washing.However,a longer fracture is not conducive to maintaining the high concentration of the HFAD agent in the matrix.Furthermore,the fracture length and pump displacement are the direct factors affecting the fluid flow velocity in the matrix subsequent to HFAD.These factors can be utilized to control the location of the displacement phase front,and thus affect the swept area of HFAD.A reasonable selection of the aforementioned parameters can effectively supplement the formation energy,expand the swept volume of the HFAD agent,improve the recovery efficiency of HFAD,and reduce the development cost.展开更多
为了解2000年以来外语电化教学研究的热点和发展动向,文章选择《外语电化教学》和Computer Assisted Language Learning两本权威期刊作为样本,通过对摘要中包含的主题词进行分析,发现国内外外语电化教学研究既存在相同之处,又有所区别...为了解2000年以来外语电化教学研究的热点和发展动向,文章选择《外语电化教学》和Computer Assisted Language Learning两本权威期刊作为样本,通过对摘要中包含的主题词进行分析,发现国内外外语电化教学研究既存在相同之处,又有所区别。文章取得的研究成果,可为今后外语电化教学的研究提供一定的启发。展开更多
To analyze the chemical constituents of volatile oils from the fruit of Periploca forrestii Schltr.which were collected in Guizhou province.This volatile oils were extracted by simultaneous distillation extraction (SD...To analyze the chemical constituents of volatile oils from the fruit of Periploca forrestii Schltr.which were collected in Guizhou province.This volatile oils were extracted by simultaneous distillation extraction (SDE)and microwave assistant extraction(MAE) method,and ananlyzed by gas chromatography-mass spectrometry(GC-MS)method.The main chemical compounds were methyl salicylate,β-amyrin and β-amyrin acetate etc.The compounds from the volatile oils extracted with SDE and MAE are quite different.The results provide scientific proof for the further development and utilization of Periploca forrestii Schltr.展开更多
Cloud Computing Assisted Instruction shows incomparable advantages over the traditional language teaching, but meanwhile, it exists some major problems, for instance, the information technology is omnipotent, informat...Cloud Computing Assisted Instruction shows incomparable advantages over the traditional language teaching, but meanwhile, it exists some major problems, for instance, the information technology is omnipotent, information input is too excessive and teachers' role is considerably weakened. This article attempts to analyze the problems and promote language teaching reform base on Cloud Computing Assisted Instruction.展开更多
It is known that the IELTS test has not been a good predictor of English capability in academic settings. More information is required. Are students not motivated to keep improving their English; what obstacles do the...It is known that the IELTS test has not been a good predictor of English capability in academic settings. More information is required. Are students not motivated to keep improving their English; what obstacles do they face? The English language issues facing international students from China at one University are explored through a survey and focus groups. It is observed that a lack of motivation is not the key factor. Rather one core problem is the very difficult demands of acculturation within a short time frame which would enable confidence for the students to continue to engage with other English speaking students. When faced with such immediate and hard to achieve acculturation, many retreat to their language groups. In the academic context, support for the transition to discipline based academic genres is double difficult as the time frame for second language learners is longer, but performance requirements are more immediate. Many first language students also have difficulties in this area, but have the easier language path to mastery. The study draws usefully on a comparison made with students studying English in China.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.52206165)。
文摘Flammable ionic liquids exhibit high conductivity and a broad electrochemical window,enabling the generation of combustible gases for combustion via electrochemical decomposition and thermal decomposition.This characteristic holds significant implications in the realm of novel satellite propulsion.Introducing a fraction of the electrical energy into energetic ionic liquid fuels,the thermal decomposition process is facilitated by reducing the apparent activation energy required,and electrical energy can trigger the electrochemical decomposition of ionic liquids,presenting a promising approach to enhance combustion efficiency and energy release.This study applied an external voltage during the thermal decomposition of 1-ethyl-3-methylimidazole nitrate([EMIm]NO_(3)),revealing the effective alteration of the activation energy of[EMIm]NO_(3).The pyrolysis,electrochemical decomposition,and electron assisted enhancement products were identified through Thermogravimetry-Differential scanning calorimetry-Fourier transform infrared-Mass spectrometry(TG-DSC-FTIR-MS)and gas chromatography(GC)analyses,elucidating the degradation mechanism of[EMIm]NO_(3).Furthermore,an external voltage was introduced during the combustion of[EMIm]NO_(3),demonstrating the impact of voltage on the combustion process.
基金supported in part by the National Natural Science Foundation of China under Grants 62325107,62341107,62261160650,and U23A20272in part by the Beijing Natural Science Foundation under Grant L222002.
文摘In this paper,we propose a sub-6GHz channel assisted hybrid beamforming(HBF)for mmWave system under both line-of-sight(LOS)and non-line-of-sight(NLOS)scenarios without mmWave channel estimation.Meanwhile,we resort to the selfsupervised approach to eliminate the need for labels,thus avoiding the accompanied high cost of data collection and annotation.We first construct the dense connection network(DCnet)with three modules:the feature extraction module for extracting channel characteristic from a large amount of channel data,the feature fusion module for combining multidimensional features,and the prediction module for generating the HBF matrices.Next,we establish a lightweight network architecture,named as LDnet,to reduce the number of model parameters and computational complexity.The proposed sub-6GHz assisted approach eliminates mmWave pilot resources compared to the method using mmWave channel information directly.The simulation results indicate that the proposed DCnet and LDnet can achieve the spectral efficiency that is superior to the traditional orthogonal matching pursuit(OMP)algorithm by 13.66% and 10.44% under LOS scenarios and by 32.35% and 27.75% under NLOS scenarios,respectively.Moreover,the LDnet achieves 98.52% reduction in the number of model parameters and 22.93% reduction in computational complexity compared to DCnet.
基金financially supported by the Key Research and Development Program of Ningbo(Grant No.2023Z098)Natural Science Foundation of Inner Mongolia(Grant No.2023MS05040)+1 种基金Shenyang Collaborative Innovation Center Project for Multiple Energy Fields Composite Processing of Special Materials(Grant No.JG210027)Shenyang Key Technology Special Project of The Open Competition Mechanism to Select the Best Solution(Grant Nos.2022210101000827,2022-0-43-048).
文摘Titanium alloy has the advantages of high strength,strong corrosion resistance,excellent high and low temperature mechanical properties,etc.,and is widely used in aerospace,shipbuilding,weapons and equipment,and other fields.In recent years,with the continuous increase in demand for medium-thick plate titanium alloys,corresponding welding technologies have also continued to develop.Therefore,this article reviews the research progress of deep penetration welding technology for medium-thick plate titanium alloys,mainly covering traditional arc welding,high-energy beam welding,and other welding technologies.Among many methods,narrow gap welding,hybrid welding,and external energy field assistance welding all contribute to improving the welding efficiency and quality of medium-thick plate titanium alloys.Finally,the development trend of deep penetration welding technology for mediumthick plate titanium alloys is prospected.
基金supported by Jiangsu Provincial Key Research and Development Program(No.BE2023014-4).
文摘During the automated placement process of dry fibers,the positioning and fixation of dry fiber gauze belts are achieved by spraying setting agents.The amount of the setting agent is difficult to control when it is sprayed manually.Furthermore,it can also affect the permeability of the preform,resin injection and the quality of the vacuum assisted resin infusion(VARI)molding,resulting in a decrease in the mechanical properties of composite materials.This study utilizes dry fiber automated placement equipment and an automated spraying system to manufacture preform structures,followed by VARI process to prepare composite samples with varying setting agent contents.Subsequently,mechanical characterization including interlaminar shear,bending and tensile testing is conducted to investigate the influence of setting agent content on both the manufacturing process and the mechanical properties of composite products.The results show that the interlaminar shear strength,bending strength and tensile strength of the sample gradually decrease with the increase of the content of the setting agent.The optimal setting agent content for automated laying of dry fiber is determined to be 4%-6%,balancing the preformed body’s layup quality and its impact on mechanical properties.Compared with agent-free samples,this range results in reductions of 3% in interlaminar shear strength,9% in bending strength,11% in bending modulus,and 13%-16% in tensile strength.
基金supported by the National Key Research and Development Program of China(2022YFE0101600)the National Natural Science Foundation of China(U23A20117)+2 种基金the Natural Science Foundation of Jiangsu Province(BK20220002,BE2022024)the Leading Talents Program of Zhejiang Province(2024C03223)Topnotch Academic Programs Project of Jiangsu Higher Education Institutions(TAPP).
文摘A two-stage catalytic membrane reactor(CMR)that couples CO_(2) splitting with methane oxidation reactions was constructed based on an oxygen-permeable perovskite asymmetric membrane.The asymmetric membrane comprises a dense SrFe_(0.9)Ta_(0.1)O_(3-σ)(SFT)separation layer and a porous Sr_(0.9)(Fe_(0.9)Ta_(0.1))_(0.9)Cu_(0.1)O_(3-σ)(SFTC)catalytic layer.In thefirst stage reactor,a CO_(2) splitting reaction(CDS:2CO_(2)→2CO+O_(2))occurs at the SFTC catalytic layer.Subsequently,the O_(2) product is selectively extracted through the SFT separation layer to the permeated side for the methane combustion reaction(MCR),which provides an extremely low oxygen partial pressure to enhance the oxygen extraction.In the second stage,a Sr_(0.9)(Fe_(0.9)Ta_(0.1))_(0.9)Ni_(0.1)O_(3-σ)(SFTN)catalyst is employed to reform the products derived from MCR.The two-stage CMR design results in a remarkable 35.4%CO_(2) conversion for CDS at 900℃.The two-stage CMR was extended to a hollowfiber configuration combining with solar irradiation.The solar-assisted two-stage CMR can operate stably for over 50 h with a high hydrogen yield of 18.1 mL min^(-1) cm^(-2).These results provide a novel strategy for reducing CO_(2) emissions,suggesting potential avenues for the design of the high-performance CMRs and catalysts based on perovskite oxides in the future.
文摘Intelligent personal assistants play a pivotal role in in-vehicle systems,significantly enhancing life efficiency,driving safety,and decision-making support.In this study,the multi-modal design elements of intelligent personal assistants within the context of visual,auditory,and somatosensory interactions with drivers were discussed.Their impact on the driver’s psychological state through various modes such as visual imagery,voice interaction,and gesture interaction were explored.The study also introduced innovative designs for in-vehicle intelligent personal assistants,incorporating design principles such as driver-centricity,prioritizing passenger safety,and utilizing timely feedback as a criterion.Additionally,the study employed design methods like driver behavior research and driving situation analysis to enhance the emotional connection between drivers and their vehicles,ultimately improving driver satisfaction and trust.
基金supported by MEXT Quantum Leap Flagship Program(MEXT Q-LEAP)Grant Number JPMXS0118067246.
文摘GHz burst-mode femtosecond(fs)laser,which emits a series of pulse trains with extremely short intervals of several hundred picoseconds,provides distinct characteristics in materials processing as compared with the conventional irradiation scheme of fs laser(single-pulse mode).In this paper,we take advantage of the moderate pulse interval of 205 ps(4.88 GHz)in the burst pulse for high-quality and high-efficiency micromachining of single crystalline sapphire by laser induced plasma assisted ablation(LIPAA).Specifically,the preceding pulses in the burst generate plasma by ablation of copper placed behind the sapphire substrate,which interacts with the subsequent pulses to induce ablation at the rear surface of sapphire substrates.As a result,not only the ablation quality but also the ablation efficiency and the fabrication resolution are greatly improved compared to the other schemes including single-pulse mode fs laser direct ablation,single-pulse mode fs-LIPAA,and nanosecond-LIPAA.
基金Supported by the National Nature Science Foundation of China(52374035,52074087)Postdoctoral Natural Science Foundation of China(2021M690528)。
文摘Considering the adsorption loss of the hydraulic fracturing assisted oil displacement(HFAD)agent in the matrix,a method is proposed to characterize the dynamic saturation adsorption capacity of the HFAD agent with pressure differential and permeability.Coupled with the viscosity-concentration relationship of the HFAD agent,a non-linear seepage model of HFAD was established,taking into account the adsorption effect of high pressure drops,and the influencing factors were analyzed.The findings indicate that the replenishment of formation energy associated with HFAD technology is predominantly influenced by matrix permeability,fracture length and the initial concentration of the HFAD agent.The effect of replenishment of formation energy is positively correlated with matrix permeability and fracture length,and negatively correlated with the initial concentration of the HFAD agent.The initial concentration and injection amount of the high-pressure HFAD agent can enhance the concentration of the HFAD agent in the matrix and improve the efficiency of oil washing.However,a longer fracture is not conducive to maintaining the high concentration of the HFAD agent in the matrix.Furthermore,the fracture length and pump displacement are the direct factors affecting the fluid flow velocity in the matrix subsequent to HFAD.These factors can be utilized to control the location of the displacement phase front,and thus affect the swept area of HFAD.A reasonable selection of the aforementioned parameters can effectively supplement the formation energy,expand the swept volume of the HFAD agent,improve the recovery efficiency of HFAD,and reduce the development cost.
文摘为了解2000年以来外语电化教学研究的热点和发展动向,文章选择《外语电化教学》和Computer Assisted Language Learning两本权威期刊作为样本,通过对摘要中包含的主题词进行分析,发现国内外外语电化教学研究既存在相同之处,又有所区别。文章取得的研究成果,可为今后外语电化教学的研究提供一定的启发。
文摘To analyze the chemical constituents of volatile oils from the fruit of Periploca forrestii Schltr.which were collected in Guizhou province.This volatile oils were extracted by simultaneous distillation extraction (SDE)and microwave assistant extraction(MAE) method,and ananlyzed by gas chromatography-mass spectrometry(GC-MS)method.The main chemical compounds were methyl salicylate,β-amyrin and β-amyrin acetate etc.The compounds from the volatile oils extracted with SDE and MAE are quite different.The results provide scientific proof for the further development and utilization of Periploca forrestii Schltr.
文摘Cloud Computing Assisted Instruction shows incomparable advantages over the traditional language teaching, but meanwhile, it exists some major problems, for instance, the information technology is omnipotent, information input is too excessive and teachers' role is considerably weakened. This article attempts to analyze the problems and promote language teaching reform base on Cloud Computing Assisted Instruction.
文摘It is known that the IELTS test has not been a good predictor of English capability in academic settings. More information is required. Are students not motivated to keep improving their English; what obstacles do they face? The English language issues facing international students from China at one University are explored through a survey and focus groups. It is observed that a lack of motivation is not the key factor. Rather one core problem is the very difficult demands of acculturation within a short time frame which would enable confidence for the students to continue to engage with other English speaking students. When faced with such immediate and hard to achieve acculturation, many retreat to their language groups. In the academic context, support for the transition to discipline based academic genres is double difficult as the time frame for second language learners is longer, but performance requirements are more immediate. Many first language students also have difficulties in this area, but have the easier language path to mastery. The study draws usefully on a comparison made with students studying English in China.
