MXenes are a novel family of two-dimensional(2D)materials that are fast gaining popularity due to their versatile characteristics.The surfaces of these materials are often functionalized by negatively charged terminal...MXenes are a novel family of two-dimensional(2D)materials that are fast gaining popularity due to their versatile characteristics.The surfaces of these materials are often functionalized by negatively charged terminal groups,such as=O,OH,and F during their synthesis,and it has been hypothesized that regulating the surface terminators enables to control the material characteristics.However,there is still a large gap between computational and experimental investigations regarding comprehending the surface functional groups.Surfaces with mixed terminations are consistently synthesized in experiments,although pure terminated surfaces are predicted by computational research.Here we summarized the nature of chemical bonding in transition metal carbide materials(MXenes)by1H and19F nuclear magnetic resonance(NMR),Raman,X-ray absorption near edge structure(XANES),extended X-ray absorption fine structure(EXAFS),ultraviolet photoelectron spectroscopy(UPS),X-ray photoelectron spectroscopy(XPS)/scanning transmission electron microscopy(STEM),and thermogravimetric analysis-mass spectrometry(TGA-MS)characterizations.Previous literature reveals that=O,–OH,–F,and–Cl are typical MXene surface terminators.However,recent comparative investigations on the valence band intensity distribution in MXenes reveal that the–OH cannot be considered an intrinsic termination species in MXenes.The surface terminals(=O,–OH,–F,and–Cl)of several MXenes,particularly V2CTxand Ti3C2Tx,will be identified and quantified here.We have also discussed different etching approaches for the synthesis of MXene,the dependence of MXene conductivity on MXene terminating groups,and the emission of various gaseous products that evolved during its chemical transformations.This paper provides significance,especially in the field of energy conversion and storage materials,where the intercalation process is crucial.展开更多
Two 2-aryl imidazo [2,1-a] isoquinolines were synthesized and tested for pregnancy terminating activities. Both of them are new compounds and their structures were confirmed by IR, (HNMR)-H-1, MS and elemental analysi...Two 2-aryl imidazo [2,1-a] isoquinolines were synthesized and tested for pregnancy terminating activities. Both of them are new compounds and their structures were confirmed by IR, (HNMR)-H-1, MS and elemental analysis. They both showed high activities in NIH mice.展开更多
In order to clarify the structural requirement of pregnancy-terminating drugs, the quantitative structure-activity relationship (QSAR) of 2-aryl imidazo[2,1-a]isoquinolines was studied on the basis of quantum mechanic...In order to clarify the structural requirement of pregnancy-terminating drugs, the quantitative structure-activity relationship (QSAR) of 2-aryl imidazo[2,1-a]isoquinolines was studied on the basis of quantum mechanical calculation and multiple regression analysis. A Good correlation equation was obtained (r2=0.925, q2=0.871). Some new compounds were designed according to the equation. Two of them, compounds 21 and 22, were synthesized and evaluated in NIH mice. The results showed that the difference of activity between 21 (median effective dose ED50=0.943 mg/kg/day) and 22 (ED50=1.099 mg/kg/day) was small and both of them were potent. It is also agreed with the computational results. Compared with L14105 which is the most potent pregnancy-terminating agent, these two compounds possess high activity. The evaluation of the anti-implanting activity showed that they were 100% effective at tested dosage 50.0, 25.0, 12.5 mg/kg/day×3 days in oral administration, which proved the both of them had anti-implanting activity and low first-pass effects.展开更多
This work presents a systematic analysis of proton-induced total ionizing dose(TID)effects in 1.2 k V silicon carbide(SiC)power devices with various edge termination structures.Three edge terminations including ring-a...This work presents a systematic analysis of proton-induced total ionizing dose(TID)effects in 1.2 k V silicon carbide(SiC)power devices with various edge termination structures.Three edge terminations including ring-assisted junction termination extension(RA-JTE),multiple floating zone JTE(MFZ-JTE),and field limiting rings(FLR)were fabricated and irradiated with45 Me V protons at fluences ranging from 1×10^(12) to 1×10^(14) cm^(-2).Experimental results,supported by TCAD simulations,show that the RA-JTE structure maintained stable breakdown performance with less than 1%variation due to its effective electric field redistribution by multiple P+rings.In contrast,MFZ-JTE and FLR exhibit breakdown voltage shifts of 6.1%and 15.2%,respectively,under the highest fluence.These results demonstrate the superior radiation tolerance of the RA-JTE structure under TID conditions and provide practical design guidance for radiation-hardened Si C power devices in space and other highradiation environments.展开更多
The Western Sichuan Foreland Basin(WSFB)in South China,a prolific hydrocarbon province,exhibits complex structural deformation influenced by Triassic salt tectonics.This paper integrates seismic data and well data to ...The Western Sichuan Foreland Basin(WSFB)in South China,a prolific hydrocarbon province,exhibits complex structural deformation influenced by Triassic salt tectonics.This paper integrates seismic data and well data to elucidate the role of Middle-Lower Triassic evaporite layers in shaping basin structures,focusing on Xinchang Tectonic Zone(XTZ).Salt layers facilitated decoupled deformation between supra-and sub-salt sequences,forming salt pillows and fault-related folds.Three distinct structural trends were identified in XTZ.Key findings reveal that salt thickness variations correlate with deformation styles:thicker salt promoted detachment folding,while thinner salt led to hard-linked fault systems.Sub-salt E-NE trending reverse faults formed horsetail terminations associated with the Pengzhou faults(PzF),deviating from the primary Longmenshan thrust belt(LmsTB)orientation.Structural evolution occurred in three stages:(1)Indosinian salt deposition and foreland basin initiation;(2)Yanshanian eastward propagation of thrust systems with salt-driven detachment folding;(3)Himalayan reactivation overprinting earlier structures with sub-NS trending folds.This work establishes a direct link between salt layers and structural traps,demonstrating how salt acted as a critical detachment layer during multi-stage compression.Results provide insights into the gas exploration of the Late Triassic Xujiahe Formation,emphasizing the importance of salt-influenced deformation in foreland basin systems.展开更多
The carboxylation of alkynes with CO_(2) has attracted considerable interest due to the valorization of C1resources and atomic economy.Much effort focused on active metals(e.g.,Au,Ag,Cu),while the mechanistic role of ...The carboxylation of alkynes with CO_(2) has attracted considerable interest due to the valorization of C1resources and atomic economy.Much effort focused on active metals(e.g.,Au,Ag,Cu),while the mechanistic role of active supports,particularly the oxygen vacancy(O_(v)),in modulating C-H bond carboxylation remains unknown.Herein,ultra-small silver clusters and morphologically engineered CeO_(2) support(nanorods,nanocubes,and nano particles)were employed to construct Ag cluster/O_(v) synergistic catalyst,which exhibits variations in Oy concentration by an in situ auto-reduction method.The 0.197%Ag/CeO_(2)-NR catalyst exhibited a high reaction rate for the phenylacetylene carboxylation reaction and the maximal silver utilization efficiency.The characterization and DFT calculations demonstrated that vacancies enhanced CO_(2) adsorption via polarization-induced molecular bending and C-O bond elongation.Positively charged Ag clusters induced by metal-support interactions serve as deprotonation activation centers for alkynes.This synergistic interplay between dual active sites efficiently facilitates the C(sp)-H carboxylation with CO_(2).These findings offer critical insights for the rational selection of active supports in designing efficient C-H carboxylation catalysts.展开更多
To explore the best preparation process for terminal blend(TB)composite-modified asphalt and to filter its formulation with excellent performance,this study evaluates the performance of TB composite modified asphalt b...To explore the best preparation process for terminal blend(TB)composite-modified asphalt and to filter its formulation with excellent performance,this study evaluates the performance of TB composite modified asphalt by physical property index,microscopic morphology,rheological testing,and infrared spectroscopy on multiple scales.The results show that the best preparation process for TB-modified asphalt is stirring at 260℃ for 4 h at 400 rpm,which significantly reduces the modification time of the asphalt.From a physical property viewpoint,the TB composite-modified asphalt sample with 5% styrene-butadiene-styrene(SBS)+1% aromatics+0.1% sulfur exhibits high-comprehensive,high-and low-temperature properties.More-over,its crosslinked mesh structure comprises black rubber particles uniformly interwoven in the middle,which further enhances the performance of the asphalt and results in an excellent performance formulation.In addition,the sample with 5%SBS content has a higher G*value and smaller δ value than that with 3%SBS content,indicating that its high-temperature resistance is improved.The effect of adding 3%SBS content on the viscoelastic ratio is,to some extent,less than that caused by 20% rubber powder.展开更多
Passengers typically spend much time in commercial zones of terminals for retail,meals,and other services.Enhancing the study of thermal comfort in this local space is necessary.The climate in the Eastern China Region...Passengers typically spend much time in commercial zones of terminals for retail,meals,and other services.Enhancing the study of thermal comfort in this local space is necessary.The climate in the Eastern China Region is variable and complex,making it more challenging to maintain the indoor thermal environment.This study conducted field measurements in winter in a commercial zone of one terminal to assess the thermal environment.Numerical simulations and PMV-PPD analyses were performed using the Computational Fluid Dynamics(CFD)program The results showed that the overall humidity in the commercial zone was low.There were notable differences in the temperatures and velocities of supply air among different air vents on the commercial island.Based on these initial conditions obtained by measurements,the simulations showed that localized areas under the breathing plane are either too hot(24℃and above)or too cold(18℃and below).The dissatisfaction percentage of the population exceeds 27%.This paper proposed that through enhancements in the air vent dimensions,layout,and air supply conditions,the temperature can be maintained in the range of 20-24℃.Furthermore,the PMV could be controlled within the range of-0.5 to 0.5.PPD was below 10%,reflecting compliance with Class I heating standards.Overall,findings from this study provide a less costly modification for thermal comfort improvement in commercial zones,and serve as a reference for the design and operation of air-conditioning systems to ensure thermal comfort in airport terminals’commercial zones.展开更多
In this paper,a unified terminal sliding mode(UTSM)control method is proposed for second-order nonlinear systems with uncertainties and disturbances.It is seen that the newly defined terminal sliding surface is integr...In this paper,a unified terminal sliding mode(UTSM)control method is proposed for second-order nonlinear systems with uncertainties and disturbances.It is seen that the newly defined terminal sliding surface is integrated with both conventional and fast terminal sliding mode and exhibits design advantages such as a variable exponent,adjustable sliding mode parameters,and chattering-alleviation effect.The inherent dynamic properties of the closed-loop systems with the UTSM control are discussed in detail via the phase plane and Lyapunov stability theory.Both numerical simulations and experimental results show the flexible sliding manifold design,strong robustness against uncertain dynamics,and effective attenuation of chattering phenomenon.展开更多
This paper investigates the termination problems of multi-path polynomial programs （MPPs） with equational loop guards. To establish sufficient conditions for termination and nontermination simultaneously, the author...This paper investigates the termination problems of multi-path polynomial programs （MPPs） with equational loop guards. To establish sufficient conditions for termination and nontermination simultaneously, the authors propose the notion of strong/weak non-termination which under/over- approximates non-termination. Based on polynomial ideal theory, the authors show that the set of all strong non-terminating inputs （SNTI） and weak non-terminating inputs （WNTI） both correspond to tile real varieties of certain polynomial ideals. Furthermore, the authors prove that the variety of SNTI is computable, and under some sufficient conditions the variety of WNTI is also computable. Then by checking the computed SNTI and WNTI varieties in parallel, termination properties of a consid- ered MPP can be asserted. As a consequence, the authors establish a new framework for termination analysis of MPPs.展开更多
We define here the concept of head boundedness,head normal form and head confluence of term rewriting systems that allow infinite derivations.Head confluence is weaker than confluence,but suffi- cient to guarantee the...We define here the concept of head boundedness,head normal form and head confluence of term rewriting systems that allow infinite derivations.Head confluence is weaker than confluence,but suffi- cient to guarantee the correctness of lazy implementations of equational logic programming languages. Then we prove several results.First,if a left-linear system is locally confluent and head-bounded,then it is head-confluent.Second,head-confluent and head-bounded systems have the head Church-Rosser proper- ty.Last,if an orthogonal system is head-terminating,then it is bead-bounded.These results can be ap- plied to generalize equational logic programming languages.展开更多
Peripheral nerve injuries result in the rapid degeneration of distal nerve segments and immediate loss of motor and sensory functions;behavioral recovery is typically poor.We used a plasmalemmal fusogen,polyethylene g...Peripheral nerve injuries result in the rapid degeneration of distal nerve segments and immediate loss of motor and sensory functions;behavioral recovery is typically poor.We used a plasmalemmal fusogen,polyethylene glycol(PEG),to immediately fuse closely apposed open ends of severed proximal and distal axons in rat sciatic nerves.We have previously reported that sciatic nerve axons repaired by PEG-fusion do not undergo Wallerian degeneration,and PEG-fused animals exhibit rapid(within 2–6 weeks)and extensive locomotor recovery.Furthermore,our previous report showed that PEG-fusion of severed sciatic motor axons was non-specific,i.e.,spinal motoneurons in PEG-fused animals were found to project to appropriate as well as inappropriate target muscles.In this study,we examined the consequences of PEG-fusion for sensory axons of the sciatic nerve.Young adult male and female rats(Sprague–Dawley)received either a unilateral single cut or ablation injury to the sciatic nerve and subsequent repair with or without(Negative Control)the application of PEG.Compound action potentials recorded immediately after PEG-fusion repair confirmed conduction across the injury site.The success of PEG-fusion was confirmed through Sciatic Functional Index testing with PEG-fused animals showing improvement in locomotor function beginning at 35 days postoperatively.At 2–42 days postoperatively,we anterogradely labeled sensory afferents from the dorsal aspect of the hindpaw following bilateral intradermal injection of wheat germ agglutinin conjugated horseradish peroxidase.PEG-fusion repair reestablished axonal continuity.Compared to unoperated animals,labeled sensory afferents ipsilateral to the injury in PEG-fused animals were found in the appropriate area of the dorsal horn,as well as inappropriate mediolateral and rostrocaudal areas.Unexpectedly,despite having intact peripheral nerves,similar reorganizations of labeled sensory afferents were also observed contralateral to the injury and repair.This central reorganization may contribute to the improved behavioral recovery seen after PEG-fusion repair,supporting the use of this novel repair methodology over currently available treatments.展开更多
This article investigates the anti-disturbance and stabilization problems for the nonlinear uncertain permanent magnet synchronous motor(PMSM)with stator voltage saturation and unknown load.A smooth switching mechanis...This article investigates the anti-disturbance and stabilization problems for the nonlinear uncertain permanent magnet synchronous motor(PMSM)with stator voltage saturation and unknown load.A smooth switching mechanism is presented to structure the adaptive integral terminal sliding mode control(SMC)strategy.The control design consists of compensation control and nominal control,which improves the rapidity and accuracy of trajectory tracking.The smooth saturation model based on the error function is applied to approximate the voltage saturation phenomenon.Additionally,to deal with the adverse effects of various unknown disturbances,including model parameter uncertainties and unknown external load disturbances,an improved disturbance observer(DO)is proposed.This observer effectively suppresses the fluctuations caused by fixed gain during the starting period of the system.Finally,the experimental results under different conditions show that the proposed strategy has good tracking and disturbance suppression performances.展开更多
This paper addresses the lane-keeping control problem for autonomous ground vehicles subject to input saturation and uncertain system parameters.An enhanced adaptive terminal sliding mode based prescribed performance ...This paper addresses the lane-keeping control problem for autonomous ground vehicles subject to input saturation and uncertain system parameters.An enhanced adaptive terminal sliding mode based prescribed performance control scheme is proposed,which enables the lateral position error of the vehicle to be kept within the prescribed performance boundaries all the time.This is achieved by firstly introducing an improved performance function into the controller design such that the stringent initial condition requirements can be relaxed,which further allows the global prescribed performance control result,and then,developing a multivariable adaptive terminal sliding mode based controller such that both input saturation and parameter uncertainties are handled effectively,which further ensures the robust lane-keeping control.Finally,the proposed control strategy is validated through numerical simulations,demonstrating its effectiveness.展开更多
In ultra-deep and large well sections,high collapse stresses and diminished annular return velocity present significant challenges to wellbore cleaning.With increasing depth,rising temperature and pressure constrain t...In ultra-deep and large well sections,high collapse stresses and diminished annular return velocity present significant challenges to wellbore cleaning.With increasing depth,rising temperature and pressure constrain the regulation of displacement and drilling fluid rheology,impairing the fluid’s capacity to transport cuttings effectively.A precise understanding of cuttings settlement behavior and terminal velocity is therefore essential for optimizing their removal.This study accounts for variations in wellbore temperature and pressure,incorporates non-spherical cuttings and wellbore diameter parameters,and develops accordingly a simplified model to predict terminal settlement velocity.Thecuttings carrying ratio is introduced as a metric for evaluatingwellbore cleanliness.Findings reveal that temperature and pressure fluctuations can alter terminal velocity by up to 3.4%.Cuttings shape plays a crucial role,with block-shaped cuttings requiring higher annular return velocity than flake-shaped ones at the same carrying ratio.As wellbore size increases,the minimum required carrying flow rate rises nonlinearly,though the rate of increase gradually declines.For a Φ444.5mmwellbore,a carrying ratio of at least 0.6 is recommended.Terminal velocity decreases with increasing consistency coefficient,particularly in high-viscosity regimes.The proposed carrying ratio offers a more accurate and practical assessment of wellbore cleanliness.展开更多
This paper presents a robust finite-time visual servo control strategy for the tracking problem of omni-directional mobile manipulators(OMMs)subject to mismatched disturbances.First,the nonlinear kinematic model of vi...This paper presents a robust finite-time visual servo control strategy for the tracking problem of omni-directional mobile manipulators(OMMs)subject to mismatched disturbances.First,the nonlinear kinematic model of visual servoing for OMMs with mismatched disturbances is explicitly presented to solve the whole-body inverse kinematic problem.Second,a sliding mode observer augmented with an integral terminal sliding mode controller is proposed to handle these uncertainties and ensure that the system converges to a small region around the equilibrium point.The boundary layer technique is employed to mitigate the chattering phenomenon.Furthermore,a strict finite-time Lyapunov stability analysis is conducted.An experimental comparison between the proposed algorithm and a traditional position-based visual servo controller is carried out,and the results demonstrate the superiority of the proposed control algorithm.展开更多
基金supported by the National Natural Science Foundation of China(21703147 and U1401248)the support of China Scholarship Council(2018SLJ022487)。
文摘MXenes are a novel family of two-dimensional(2D)materials that are fast gaining popularity due to their versatile characteristics.The surfaces of these materials are often functionalized by negatively charged terminal groups,such as=O,OH,and F during their synthesis,and it has been hypothesized that regulating the surface terminators enables to control the material characteristics.However,there is still a large gap between computational and experimental investigations regarding comprehending the surface functional groups.Surfaces with mixed terminations are consistently synthesized in experiments,although pure terminated surfaces are predicted by computational research.Here we summarized the nature of chemical bonding in transition metal carbide materials(MXenes)by1H and19F nuclear magnetic resonance(NMR),Raman,X-ray absorption near edge structure(XANES),extended X-ray absorption fine structure(EXAFS),ultraviolet photoelectron spectroscopy(UPS),X-ray photoelectron spectroscopy(XPS)/scanning transmission electron microscopy(STEM),and thermogravimetric analysis-mass spectrometry(TGA-MS)characterizations.Previous literature reveals that=O,–OH,–F,and–Cl are typical MXene surface terminators.However,recent comparative investigations on the valence band intensity distribution in MXenes reveal that the–OH cannot be considered an intrinsic termination species in MXenes.The surface terminals(=O,–OH,–F,and–Cl)of several MXenes,particularly V2CTxand Ti3C2Tx,will be identified and quantified here.We have also discussed different etching approaches for the synthesis of MXene,the dependence of MXene conductivity on MXene terminating groups,and the emission of various gaseous products that evolved during its chemical transformations.This paper provides significance,especially in the field of energy conversion and storage materials,where the intercalation process is crucial.
文摘Two 2-aryl imidazo [2,1-a] isoquinolines were synthesized and tested for pregnancy terminating activities. Both of them are new compounds and their structures were confirmed by IR, (HNMR)-H-1, MS and elemental analysis. They both showed high activities in NIH mice.
文摘In order to clarify the structural requirement of pregnancy-terminating drugs, the quantitative structure-activity relationship (QSAR) of 2-aryl imidazo[2,1-a]isoquinolines was studied on the basis of quantum mechanical calculation and multiple regression analysis. A Good correlation equation was obtained (r2=0.925, q2=0.871). Some new compounds were designed according to the equation. Two of them, compounds 21 and 22, were synthesized and evaluated in NIH mice. The results showed that the difference of activity between 21 (median effective dose ED50=0.943 mg/kg/day) and 22 (ED50=1.099 mg/kg/day) was small and both of them were potent. It is also agreed with the computational results. Compared with L14105 which is the most potent pregnancy-terminating agent, these two compounds possess high activity. The evaluation of the anti-implanting activity showed that they were 100% effective at tested dosage 50.0, 25.0, 12.5 mg/kg/day×3 days in oral administration, which proved the both of them had anti-implanting activity and low first-pass effects.
基金supported by the IITP(Institute for Information&Communications Technology Planning&Evaluation)under the ITRC(Information Technology Research Center)support program(IITP-2025-RS-2024-00438288)grant funded by the Korea government(MSIT)+1 种基金National Research Council of Science&Technology(NST)grant by the MSIT(Aerospace Semiconductor Strategy Research Project No.GTL25051-000)supported by the IC Design Education Center(IDEC),Korea。
文摘This work presents a systematic analysis of proton-induced total ionizing dose(TID)effects in 1.2 k V silicon carbide(SiC)power devices with various edge termination structures.Three edge terminations including ring-assisted junction termination extension(RA-JTE),multiple floating zone JTE(MFZ-JTE),and field limiting rings(FLR)were fabricated and irradiated with45 Me V protons at fluences ranging from 1×10^(12) to 1×10^(14) cm^(-2).Experimental results,supported by TCAD simulations,show that the RA-JTE structure maintained stable breakdown performance with less than 1%variation due to its effective electric field redistribution by multiple P+rings.In contrast,MFZ-JTE and FLR exhibit breakdown voltage shifts of 6.1%and 15.2%,respectively,under the highest fluence.These results demonstrate the superior radiation tolerance of the RA-JTE structure under TID conditions and provide practical design guidance for radiation-hardened Si C power devices in space and other highradiation environments.
基金supported by the National Science Foundation of China(Grant No.41602161,92255302)the National Science and Technology Major Project of China(Project No.2016ZX05033)Sinopec Science and Technology Development Project(Project No.P18089-1,P22085).
文摘The Western Sichuan Foreland Basin(WSFB)in South China,a prolific hydrocarbon province,exhibits complex structural deformation influenced by Triassic salt tectonics.This paper integrates seismic data and well data to elucidate the role of Middle-Lower Triassic evaporite layers in shaping basin structures,focusing on Xinchang Tectonic Zone(XTZ).Salt layers facilitated decoupled deformation between supra-and sub-salt sequences,forming salt pillows and fault-related folds.Three distinct structural trends were identified in XTZ.Key findings reveal that salt thickness variations correlate with deformation styles:thicker salt promoted detachment folding,while thinner salt led to hard-linked fault systems.Sub-salt E-NE trending reverse faults formed horsetail terminations associated with the Pengzhou faults(PzF),deviating from the primary Longmenshan thrust belt(LmsTB)orientation.Structural evolution occurred in three stages:(1)Indosinian salt deposition and foreland basin initiation;(2)Yanshanian eastward propagation of thrust systems with salt-driven detachment folding;(3)Himalayan reactivation overprinting earlier structures with sub-NS trending folds.This work establishes a direct link between salt layers and structural traps,demonstrating how salt acted as a critical detachment layer during multi-stage compression.Results provide insights into the gas exploration of the Late Triassic Xujiahe Formation,emphasizing the importance of salt-influenced deformation in foreland basin systems.
基金financially supported by the National Natural Science Foundation of China(22102194)the Science and Technology Plan of Gansu Province(24JRRA067,23ZDFA016)the Youth Innovation Promotion Association of CAS(2022427)。
文摘The carboxylation of alkynes with CO_(2) has attracted considerable interest due to the valorization of C1resources and atomic economy.Much effort focused on active metals(e.g.,Au,Ag,Cu),while the mechanistic role of active supports,particularly the oxygen vacancy(O_(v)),in modulating C-H bond carboxylation remains unknown.Herein,ultra-small silver clusters and morphologically engineered CeO_(2) support(nanorods,nanocubes,and nano particles)were employed to construct Ag cluster/O_(v) synergistic catalyst,which exhibits variations in Oy concentration by an in situ auto-reduction method.The 0.197%Ag/CeO_(2)-NR catalyst exhibited a high reaction rate for the phenylacetylene carboxylation reaction and the maximal silver utilization efficiency.The characterization and DFT calculations demonstrated that vacancies enhanced CO_(2) adsorption via polarization-induced molecular bending and C-O bond elongation.Positively charged Ag clusters induced by metal-support interactions serve as deprotonation activation centers for alkynes.This synergistic interplay between dual active sites efficiently facilitates the C(sp)-H carboxylation with CO_(2).These findings offer critical insights for the rational selection of active supports in designing efficient C-H carboxylation catalysts.
基金Funded by the National Natural Science Foundation of China(No.52278446)。
文摘To explore the best preparation process for terminal blend(TB)composite-modified asphalt and to filter its formulation with excellent performance,this study evaluates the performance of TB composite modified asphalt by physical property index,microscopic morphology,rheological testing,and infrared spectroscopy on multiple scales.The results show that the best preparation process for TB-modified asphalt is stirring at 260℃ for 4 h at 400 rpm,which significantly reduces the modification time of the asphalt.From a physical property viewpoint,the TB composite-modified asphalt sample with 5% styrene-butadiene-styrene(SBS)+1% aromatics+0.1% sulfur exhibits high-comprehensive,high-and low-temperature properties.More-over,its crosslinked mesh structure comprises black rubber particles uniformly interwoven in the middle,which further enhances the performance of the asphalt and results in an excellent performance formulation.In addition,the sample with 5%SBS content has a higher G*value and smaller δ value than that with 3%SBS content,indicating that its high-temperature resistance is improved.The effect of adding 3%SBS content on the viscoelastic ratio is,to some extent,less than that caused by 20% rubber powder.
基金supported by the National Natural Science Foundation of China(52478098)the Natural Science Foundation of Shanghai Municipality(21ZR1444800)the Shanghai Sailing Program(21YF1430700).
文摘Passengers typically spend much time in commercial zones of terminals for retail,meals,and other services.Enhancing the study of thermal comfort in this local space is necessary.The climate in the Eastern China Region is variable and complex,making it more challenging to maintain the indoor thermal environment.This study conducted field measurements in winter in a commercial zone of one terminal to assess the thermal environment.Numerical simulations and PMV-PPD analyses were performed using the Computational Fluid Dynamics(CFD)program The results showed that the overall humidity in the commercial zone was low.There were notable differences in the temperatures and velocities of supply air among different air vents on the commercial island.Based on these initial conditions obtained by measurements,the simulations showed that localized areas under the breathing plane are either too hot(24℃and above)or too cold(18℃and below).The dissatisfaction percentage of the population exceeds 27%.This paper proposed that through enhancements in the air vent dimensions,layout,and air supply conditions,the temperature can be maintained in the range of 20-24℃.Furthermore,the PMV could be controlled within the range of-0.5 to 0.5.PPD was below 10%,reflecting compliance with Class I heating standards.Overall,findings from this study provide a less costly modification for thermal comfort improvement in commercial zones,and serve as a reference for the design and operation of air-conditioning systems to ensure thermal comfort in airport terminals’commercial zones.
基金supported by the National Natural Science Foundation of China(62473337,62003305)the Key Research and Development Program of Zhejiang Province(2024C03040,2022C03029)the Leading Innovative and Entrepreneur Team Introduction Program of Zhejiang Province(2023R01006)。
文摘In this paper,a unified terminal sliding mode(UTSM)control method is proposed for second-order nonlinear systems with uncertainties and disturbances.It is seen that the newly defined terminal sliding surface is integrated with both conventional and fast terminal sliding mode and exhibits design advantages such as a variable exponent,adjustable sliding mode parameters,and chattering-alleviation effect.The inherent dynamic properties of the closed-loop systems with the UTSM control are discussed in detail via the phase plane and Lyapunov stability theory.Both numerical simulations and experimental results show the flexible sliding manifold design,strong robustness against uncertain dynamics,and effective attenuation of chattering phenomenon.
基金supported by the National Basic Research Program of China under Grant No.2014CB340700the National Science and Technology Major Project of China under Grant No.2012ZX01039-004+3 种基金the National Natural Science Foundation of China under Grant Nos.91118007,11071273,61202131,11401218,cstc2012ggB40004,cstc2013jjys40001SRFDP under Grant No.20130076120010the Open Project of Shanghai Key Laboratory of Trustworthy Computing under Grant No.07dz22304201307West Light Foundation of Chinese Academy of Sciences
文摘This paper investigates the termination problems of multi-path polynomial programs （MPPs） with equational loop guards. To establish sufficient conditions for termination and nontermination simultaneously, the authors propose the notion of strong/weak non-termination which under/over- approximates non-termination. Based on polynomial ideal theory, the authors show that the set of all strong non-terminating inputs （SNTI） and weak non-terminating inputs （WNTI） both correspond to tile real varieties of certain polynomial ideals. Furthermore, the authors prove that the variety of SNTI is computable, and under some sufficient conditions the variety of WNTI is also computable. Then by checking the computed SNTI and WNTI varieties in parallel, termination properties of a consid- ered MPP can be asserted. As a consequence, the authors establish a new framework for termination analysis of MPPs.
基金The project is supported by the National Natural Science Foundation of China.
文摘We define here the concept of head boundedness,head normal form and head confluence of term rewriting systems that allow infinite derivations.Head confluence is weaker than confluence,but suffi- cient to guarantee the correctness of lazy implementations of equational logic programming languages. Then we prove several results.First,if a left-linear system is locally confluent and head-bounded,then it is head-confluent.Second,head-confluent and head-bounded systems have the head Church-Rosser proper- ty.Last,if an orthogonal system is head-terminating,then it is bead-bounded.These results can be ap- plied to generalize equational logic programming languages.
基金supported by the Department of Defense AFIRMⅢW81XWH-20-2-0029 grant subcontractLone Star Paralysis gift,UT POC19-1774-13 grant+1 种基金Neuraptive Therapeutics Inc.26-7724-56 grantNational Institutes of Health R01-NS128086(all to GDB)。
文摘Peripheral nerve injuries result in the rapid degeneration of distal nerve segments and immediate loss of motor and sensory functions;behavioral recovery is typically poor.We used a plasmalemmal fusogen,polyethylene glycol(PEG),to immediately fuse closely apposed open ends of severed proximal and distal axons in rat sciatic nerves.We have previously reported that sciatic nerve axons repaired by PEG-fusion do not undergo Wallerian degeneration,and PEG-fused animals exhibit rapid(within 2–6 weeks)and extensive locomotor recovery.Furthermore,our previous report showed that PEG-fusion of severed sciatic motor axons was non-specific,i.e.,spinal motoneurons in PEG-fused animals were found to project to appropriate as well as inappropriate target muscles.In this study,we examined the consequences of PEG-fusion for sensory axons of the sciatic nerve.Young adult male and female rats(Sprague–Dawley)received either a unilateral single cut or ablation injury to the sciatic nerve and subsequent repair with or without(Negative Control)the application of PEG.Compound action potentials recorded immediately after PEG-fusion repair confirmed conduction across the injury site.The success of PEG-fusion was confirmed through Sciatic Functional Index testing with PEG-fused animals showing improvement in locomotor function beginning at 35 days postoperatively.At 2–42 days postoperatively,we anterogradely labeled sensory afferents from the dorsal aspect of the hindpaw following bilateral intradermal injection of wheat germ agglutinin conjugated horseradish peroxidase.PEG-fusion repair reestablished axonal continuity.Compared to unoperated animals,labeled sensory afferents ipsilateral to the injury in PEG-fused animals were found in the appropriate area of the dorsal horn,as well as inappropriate mediolateral and rostrocaudal areas.Unexpectedly,despite having intact peripheral nerves,similar reorganizations of labeled sensory afferents were also observed contralateral to the injury and repair.This central reorganization may contribute to the improved behavioral recovery seen after PEG-fusion repair,supporting the use of this novel repair methodology over currently available treatments.
基金supported by the National Natural Science Foundation under Grant 62273189the Shandong Province Natural Science Foundation under Grant ZR2021MF005Systems Science Plus Joint Research Program of Qingdao University under Grant XT2024201 of China supporting this research work.
文摘This article investigates the anti-disturbance and stabilization problems for the nonlinear uncertain permanent magnet synchronous motor(PMSM)with stator voltage saturation and unknown load.A smooth switching mechanism is presented to structure the adaptive integral terminal sliding mode control(SMC)strategy.The control design consists of compensation control and nominal control,which improves the rapidity and accuracy of trajectory tracking.The smooth saturation model based on the error function is applied to approximate the voltage saturation phenomenon.Additionally,to deal with the adverse effects of various unknown disturbances,including model parameter uncertainties and unknown external load disturbances,an improved disturbance observer(DO)is proposed.This observer effectively suppresses the fluctuations caused by fixed gain during the starting period of the system.Finally,the experimental results under different conditions show that the proposed strategy has good tracking and disturbance suppression performances.
基金supported in part by the National Key Research and Development Program of China under Grant 2023YFA1011803in part by Natural Science Foundation of Chongqing,China under Grant CSTB2023NSCQ-MSX0588+2 种基金in part by the Fundamental Research Funds for the Central Universities,China under Grant 2023CDJKYJH047in part by the National Natural Science Foundation of China under Grant 62273064,Grant 61991400,Grant 61991403,Grant 61933012,Grant 62250710167,Grant 62203078in part by Innovation Support Program for International Students Returning to China under Grant cx2022016.
文摘This paper addresses the lane-keeping control problem for autonomous ground vehicles subject to input saturation and uncertain system parameters.An enhanced adaptive terminal sliding mode based prescribed performance control scheme is proposed,which enables the lateral position error of the vehicle to be kept within the prescribed performance boundaries all the time.This is achieved by firstly introducing an improved performance function into the controller design such that the stringent initial condition requirements can be relaxed,which further allows the global prescribed performance control result,and then,developing a multivariable adaptive terminal sliding mode based controller such that both input saturation and parameter uncertainties are handled effectively,which further ensures the robust lane-keeping control.Finally,the proposed control strategy is validated through numerical simulations,demonstrating its effectiveness.
基金partly supported by the National Natural Science Foundation of China(52304045)the Open Fund(PLN2023-40)of the National Key Laboratory of Oil and Gas Reservoir Geology and Exploitation(Southwest Petroleum University)the Open Fund(2024-KFKT-08)of China National Petroleum Corporation Science and Technology Research Institute.
文摘In ultra-deep and large well sections,high collapse stresses and diminished annular return velocity present significant challenges to wellbore cleaning.With increasing depth,rising temperature and pressure constrain the regulation of displacement and drilling fluid rheology,impairing the fluid’s capacity to transport cuttings effectively.A precise understanding of cuttings settlement behavior and terminal velocity is therefore essential for optimizing their removal.This study accounts for variations in wellbore temperature and pressure,incorporates non-spherical cuttings and wellbore diameter parameters,and develops accordingly a simplified model to predict terminal settlement velocity.Thecuttings carrying ratio is introduced as a metric for evaluatingwellbore cleanliness.Findings reveal that temperature and pressure fluctuations can alter terminal velocity by up to 3.4%.Cuttings shape plays a crucial role,with block-shaped cuttings requiring higher annular return velocity than flake-shaped ones at the same carrying ratio.As wellbore size increases,the minimum required carrying flow rate rises nonlinearly,though the rate of increase gradually declines.For a Φ444.5mmwellbore,a carrying ratio of at least 0.6 is recommended.Terminal velocity decreases with increasing consistency coefficient,particularly in high-viscosity regimes.The proposed carrying ratio offers a more accurate and practical assessment of wellbore cleanliness.
基金supported by the Artificial Intelligence Innovation and Development Special Fund of Shanghai(No.2019RGZN01041)the National Natural Science Foundation of China(No.92048205).
文摘This paper presents a robust finite-time visual servo control strategy for the tracking problem of omni-directional mobile manipulators(OMMs)subject to mismatched disturbances.First,the nonlinear kinematic model of visual servoing for OMMs with mismatched disturbances is explicitly presented to solve the whole-body inverse kinematic problem.Second,a sliding mode observer augmented with an integral terminal sliding mode controller is proposed to handle these uncertainties and ensure that the system converges to a small region around the equilibrium point.The boundary layer technique is employed to mitigate the chattering phenomenon.Furthermore,a strict finite-time Lyapunov stability analysis is conducted.An experimental comparison between the proposed algorithm and a traditional position-based visual servo controller is carried out,and the results demonstrate the superiority of the proposed control algorithm.
