The minimal widths of three bounded subsets of the unit sphere associated to a unit vector in a normed linear space are studied,and three related geometric constants are introduced.New characterizations of inner produ...The minimal widths of three bounded subsets of the unit sphere associated to a unit vector in a normed linear space are studied,and three related geometric constants are introduced.New characterizations of inner product spaces are also presented.From the perspective of minimal width,strongε-symmetry of Birkhoff orthogonality is introduced,and its relation toε-symmetry of Birkhoff orthogonality is shown.Unlike most of the existing parameters of the underlying space,these new constants are full dimensional in nature.展开更多
The wavelength-tunable and switchable narrow bandwidth mode-locking operation is demonstrated in an all fiber laser based on semiconductor-saturable absorber mirror （SESAM）. Two narrow-band fiber Bragg gratings cent...The wavelength-tunable and switchable narrow bandwidth mode-locking operation is demonstrated in an all fiber laser based on semiconductor-saturable absorber mirror （SESAM）. Two narrow-band fiber Bragg gratings centered at 1029.9nm and 1032nm respectively with a polarization controller inserted between them are used to realize the wavelength switchable between 1029.9nm and 1032nm. The laser delivers different pulse widths of 7.5ps for 1030nm and 20ps for 1032nm. The maximum output power for both could reach -6.5mW at single pulse operation. The output wavelength couM be tuned to about 0.gnm intervals ranging from 1030.2nm to 1031.1 nm and from 1032.15nm to 1033.7nm with the temperature change of the fiber Bragg grating, respectively.展开更多
We performed systematic laser spectroscopic investigations of La I spectral lines, using optogalvanic detection. Sixteen previously unknown even parity levels, having energies between 40,300 and 44,300 cm<sup>-1...We performed systematic laser spectroscopic investigations of La I spectral lines, using optogalvanic detection. Sixteen previously unknown even parity levels, having energies between 40,300 and 44,300 cm<sup>-1</sup>, are reported. These levels classify altogether 67 lines, not listed in spectral tables. The new levels were found due to the observation of the depopulation of the lower levels of the excited transitions. We found a remarkable variation of the observed widths of single hyperfine structure components dependent on the energy of the upper excited levels. Some levels having energies higher than 43,000 cm<sup>-1</sup> appear to have a very high ionization probability.展开更多
The article concerns the average onesided widths of the Sobolev and Besov classes and the classes of functions with bounded moduli of smoothness. The weak asymptotic results are obtained for the corresponding quantities.
The edge plasma code package SOLPS5.0 is employed to simulate the divertor power footprint widths of the experimental advanced superconducting tokamak （EAST） L-mode and ELM-free H-mode plasmas.The divertor power foo...The edge plasma code package SOLPS5.0 is employed to simulate the divertor power footprint widths of the experimental advanced superconducting tokamak （EAST） L-mode and ELM-free H-mode plasmas.The divertor power footprint widths,which consist of the scrape-off layer （SOL） width λq and heat spreading S,are important physical parameters for edge plasmas.In this work,a plasma current scan is implemented in the simulation to obtain the dependence of the divertor power footprint width on the plasma current Ip.Strong inverse scaling of the SOL width with Ip has been achieved for both L-mode and H-mode plasmas in the forms of λq,L-mode =4.98 × Ip-0.68 and λq,H-mode =1.86 × Ip-1.08.Similar trends have also been demonstrated in the study of heat spreading with SL-mode =1.95 × Ip-0.542 and SH-mode =0.756 × Ip-0.872.In addition,studies on divertor peak heat load and the magnetic flux expansion factor show that both of them are proportional to plasma current.The simulation work here can act as a way to explore the power footprint widths of future tokamak fusion devices such as ITER and the China Fusion Engineering Test Reactor （CFETR）.展开更多
In this paper we study the average σ-K width and the average σ-linear width of the unit ball of l;（R） inl;（R）. The exact values of these widths are calculated and an optimal subspace with the optimal linear oper...In this paper we study the average σ-K width and the average σ-linear width of the unit ball of l;（R） inl;（R）. The exact values of these widths are calculated and an optimal subspace with the optimal linear opera-tor （for the σ- linear width） are identified.展开更多
In this paper,a kind of generalized Sobolev-Wiener classes W_(pq)~y(R,h),h>0,defined on the whole real axis,is introduced,and the average σ-K width problem of these function classes in the metric L_q(R)is studied....In this paper,a kind of generalized Sobolev-Wiener classes W_(pq)~y(R,h),h>0,defined on the whole real axis,is introduced,and the average σ-K width problem of these function classes in the metric L_q(R)is studied.For the case p=+∞,1≤q≤+∞,the case 1≤p <+∞,q=1,we get their exact values and identify their optimal subspaces.展开更多
A simple rectangular microstrip antenna on low dielectric constant substrate such as air for improved radiation beam performance is theoretically investigated. The conventional patch antenna fabricated on common subst...A simple rectangular microstrip antenna on low dielectric constant substrate such as air for improved radiation beam performance is theoretically investigated. The conventional patch antenna fabricated on common substrates always produces quite broader E plane pattern compared to its H plane. In the present investigation, the same microstrip antenna is designed on air substrate with a view to develop an efficient feed for parabolic reflector antenna, which shows an excellent radiation pattern with symmetrical 3 dB beam widths at its both E and H plane. The present antenna compared to conventional structure to show its excellence in the beam performance is presented. The complete quantitative analysis to explore such radiation beam characteristics for both the structures (conventional and the present one) is also presented in this paper. An easy and handful relationship between the length of patch antenna and its fringing length for different types of substrate is established in the background of 3 dB beam widths. The proposed idea has been verified through a commercial software package for a patch operating in X band and a concrete physical insight into the phenomenon is developed.展开更多
n this paper, the relative widths of some sets in are studied. Relative widths is the further development of Kolmogorov widths and it is a new problem in approximation theory which aroused some mathematics workers gre...n this paper, the relative widths of some sets in are studied. Relative widths is the further development of Kolmogorov widths and it is a new problem in approximation theory which aroused some mathematics workers great interest recently. We present some basic propositions of relative widths and investigate relative widths of some sets (ball or ellipsoid)展开更多
We present the discovery of 18 narrow line Seyfert 1 galaxies (NLS1). The optical spectra show the Balmer lines only slightly broader than the forbidden lines and contain strong Fe Ⅱ emission. No particularly soft X ...We present the discovery of 18 narrow line Seyfert 1 galaxies (NLS1). The optical spectra show the Balmer lines only slightly broader than the forbidden lines and contain strong Fe Ⅱ emission. No particularly soft X ray spectral slopes can be seen compared to a normal Seyfert 1 galaxies sample.展开更多
Computational simulations and high-temperature measurements of velocities near the surface of a mold were carried out by using the rod deflection method to study the effects of various operating parameters on the flow...Computational simulations and high-temperature measurements of velocities near the surface of a mold were carried out by using the rod deflection method to study the effects of various operating parameters on the flow field in slab continuous casting(CC)molds with narrow widths for the production of automobile exposed panels.Reasonable agreement between the calculated results and measured subsurface velocities of liquid steel was obtained under different operating parameters of the CC process.The simulation results reveal that the flow field in the horizontal plane located 50 mm from the meniscus can be used as the characteristic flow field to optimize the flow field of molten steel in the mold.Increases in casting speed can increase the subsurface velocity of molten steel and shift the position of the vortex core downward in the downward circulation zone.The flow field of liquid steel in a 1040 mm-wide slab CC mold can be improved by an Ar gas flow rate of 7 L·min^−1 and casting speed of 1.7 m·min^−1.Under the present experimental conditions,the double-roll flow pattern is generally stable at a submerged entry nozzle immersion depth of 170 mm.展开更多
The surface dielectric barrier discharge （SDBD） plasma actuator has shown great promise as an aerodynamic flow control device. In this paper, the encapsulated electrode width of a SDBD actuator is changed to study t...The surface dielectric barrier discharge （SDBD） plasma actuator has shown great promise as an aerodynamic flow control device. In this paper, the encapsulated electrode width of a SDBD actuator is changed to study the airflow acceleration behavior. The effects of encapsulated electrode width on the actuator performance are experimentally investigated by measuring the dielectric layer surface potential, time-averaged ionic wind velocity and thrust force. Experimental results show that the airflow velocity and thrust force increase with the encapsulated electrode width. The results can be attributed to the distinct plasma distribution at different encapsulated electrode widths.展开更多
To investigate the impact of combustor width on continuous rotating detonation(CRD)fueled by ethylene and air,a series of 3 D simulations are conducted by changing the inner cylinder radius of an annular combustor whi...To investigate the impact of combustor width on continuous rotating detonation(CRD)fueled by ethylene and air,a series of 3 D simulations are conducted by changing the inner cylinder radius of an annular combustor while retaining the same outer cylinder radius.The results show that the CRD wave propagates more steadily and faster as the combustor width increases.The high-temperature zone at the backward-facing step preheats the propellants and contributes to the steady propagation of the CRD wave in 25-and 30-mm wide combustors.The highest and the lowest velocities are obtained in the30-and 15-mm wide combustors at,respectively,1880.27 and 1681.01 m/s.On the other hand,the average thrust decreases as the combustor width increases.The highest thrust is obtained in the 15-mm wide combustor while the lowest is in the 30-mm wide combustor,at 758.06 and 525.93 N,respectively.Nevertheless,the thrust is much more stable in the 25-and 30-mm wide combustors than in the 15-and 20-mm wide combustors.展开更多
This paper concerns the problem of the Kolmogorov n-width, the linear re-width, the Gel'fand n-width and the Bernstein re-width of Sobolev classes of the periodic multivariate functions in the space Lp(Td) and the...This paper concerns the problem of the Kolmogorov n-width, the linear re-width, the Gel'fand n-width and the Bernstein re-width of Sobolev classes of the periodic multivariate functions in the space Lp(Td) and the average Bernstein o-width, average Kolmogorov o-widths, the average linear o-widths of Sobolev classes of the multivariate functions in the space LP(R ), where p = (p1,…,pd), 1 < Pj < ∞o, j = 1,2,…,d, or pj = ∞,j = 1,2,…, d. Their weak asymptotic behaviors are established for the corresponding quantities.展开更多
This study was undertaken to examine which factors contributed to the correction of crowding in two patients who underwent nonextraction orthodontic treatment. A study model analysis was conducted to determine the eff...This study was undertaken to examine which factors contributed to the correction of crowding in two patients who underwent nonextraction orthodontic treatment. A study model analysis was conducted to determine the effects of the orthodontic treatment for crowding with high canines on crown angulation and dental arch width in two patients. The results showed that the crown angulation was significantly increased, indicating distal tipping in the maxillary dental arch. This tendency was most commonly observed in the premolars among the lateral teeth. With respect to the dental arch width, the largest change was evident in the first molar and first premolar regions in cases 1 and 2, respectively. On the basis of these results, up-righting of mesially tipped lateral teeth and expansion of narrow dental arches could prove to be the keys to the success of space regaining or correction of high canines and mild crowding.展开更多
Probabilistic linear （N, δ）-widths and p-average linear N-widths of Sobolev space W2^r（T）, equipped with a Gaussian probability measure #, are studied in the metric of Sq （T） （1 ≤ Q ≤∞）, and determined the...Probabilistic linear （N, δ）-widths and p-average linear N-widths of Sobolev space W2^r（T）, equipped with a Gaussian probability measure #, are studied in the metric of Sq （T） （1 ≤ Q ≤∞）, and determined the asymptotic equalities：λN,δ（W2^r（T）,μ,Sq（T））={（N^-1）^r＋p/2-1/q√1＋1/N·ln1/δ, 1≤q≤2, （N^-1）^r＋p/2-1/q（1＋N^-1/q√ln1/δ）,2〈q〈∞, （N^-1）^r＋p/2√lnN/δ, q=∞,and λN^（a）（W2^r（T）,μ,Sq（T））p={（N^-1）^r＋p/2-1/q, 1≤q〈∞, （N^-1）^r＋p/2-1/q√lnN, q=∞,where 0 〈 p 〈 ∞, δ∈ （0, 1/2], ρ 〉 1, and Sq（T） is a subspace of L1（T）, in which the Fourier series is absolutely convergent in lq sense.展开更多
Large-area patterned films of boron nanowires（BNWs） are fabricated at various densities by chemical vapor deposition（CVD）. Different widths of unit-cell of Mo masks are used as templates. The widths of unit-cell o...Large-area patterned films of boron nanowires（BNWs） are fabricated at various densities by chemical vapor deposition（CVD）. Different widths of unit-cell of Mo masks are used as templates. The widths of unit-cell of Mo masks are100 μm, 150 μm, and 200 μm, respectively. The distance between unit cells is 50 μm. The BNWs have an average diameter of about 20 nm and lengths of 10 μm–20 μm. High-resolution transmission electron microscopy analysis shows that each nanowire has a β-tetragonal structure with good crystallization. Field emission measurements of the BNW films show that their turn-on electric fields decrease with width of unit-cell increasing.展开更多
The power-function exponent b of at-a-station hydraulic geometry(AHG)depicts the temporal response of river hydraulic parameters to changing discharge and is crucial for hydraulic modeling,habitat assessment,and river...The power-function exponent b of at-a-station hydraulic geometry(AHG)depicts the temporal response of river hydraulic parameters to changing discharge and is crucial for hydraulic modeling,habitat assessment,and river management.However,previous research,limited by field measurements,offers only a fragmentary understanding of the AHG exponent b in confined areas.Additionally,it remains challenging to establish the correlation between b and the climatic regime of a river.To offer a more comprehensive scope of AHG,this study assesses the width-discharge AHG exponents of 1,568 river reaches by pairing multi-temporal river width data from 1.19 million Landsat images with discharge observations from>17,000 gauge stations worldwide.The results show that b has a median value of 0.213,consistent with values reported in previous regional studies,but it exhibits complex relationships with 3 spatial dimensions-latitude,elevation,and drainage area.We further analyze the spatial variations in b against>200 physiographic and climatic factors,and find that reaches characterized by cohesive soil,high forest coverage,and less anthropogenic influences typically exhibit lower values of b,indicating a weaker response of width to discharge changes.By labeling 4 planimetric river morphologic types globally,we show that braided reaches exhibit the highest median of b,followed by straight,anabranching,and meandering reaches.The differences can be well explained by the climatic conditions of the river reaches as shown on the Budyko curve.This study lays the foundation for AHG research in ungauged regions using satellite remote sensing,expanding global hydraulic data and enhancing the understanding of the spatial variability and influencing factors of hydraulic geometry worldwide.展开更多
The four-level nested neutral-point-clamped(4L-NNPC)inverter is a competitive topology among the various medium-voltage multilevel converters,and its main issue is flying-capacitor voltage unbalance.In this article,a ...The four-level nested neutral-point-clamped(4L-NNPC)inverter is a competitive topology among the various medium-voltage multilevel converters,and its main issue is flying-capacitor voltage unbalance.In this article,a novel carrier-interleaved pulse width modulation(CIPWM)method that satisfies the volt-sec balance principle is proposed with an advanced carrier distribution rule.By adopting the proposed CIPWM method,the redundant switching states of 4L-NNPC inverters can be evenly distributed into the output PWM waveform in each carrier period,and natural flying-capacitor voltage balance can be achieved.Furthermore,an active balancing strategy is also proposed to eliminate the voltage unbalance caused by nonideal factors,which is realized by simply adjusting the duty cycle and with no need to adjust the redundant switching states for 4L-NNPC inverters.The simulation and experimental results verify the effectiveness of the proposed CIPWM method and the flying-capacitor voltage balancing strategy.展开更多
BACKGROUND Red blood cell distribution width(RDW)is associated with the development and progression of various diseases.AIM To explore the association between pretreatment RDW and short-term outcomes after laparoscopi...BACKGROUND Red blood cell distribution width(RDW)is associated with the development and progression of various diseases.AIM To explore the association between pretreatment RDW and short-term outcomes after laparoscopic pancreatoduodenectomy(LPD).METHODS A total of 804 consecutive patients who underwent LPD at our hospital between March 2017 and November 2021 were retrospectively analyzed.Correlations between pretreatment RDW and clinicopathological characteristics and short-term outcomes were investigated.RESULTS Patients with higher pretreatment RDW were older,had higher Eastern Cooperative Oncology Group scores and were associated with poorer short-term outcomes than those with normal RDW.High pretreatment RDW was an independent risk factor for postoperative complications(POCs)(hazard ratio=2.973,95%confidence interval:2.032-4.350,P<0.001)and severe POCs of grade IIIa or higher(hazard ratio=3.138,95%confidence interval:2.042-4.824,P<0.001)based on the Clavien-Dino classification system.Subgroup analysis showed that high pretreatment RDW was an independent risk factor for Clavien-Dino classi-fication grade IIIb or higher POCs,a comprehensive complication index score≥26.2,severe postoperative pancreatic fistula,severe bile leakage and severe hemorrhage.High pretreatment RDW was positively associated with the neutrophil-to-lymphocyte ratio and platelet-to-lymphocyte ratio and was negatively associated with albumin and the prognostic nutritional index.CONCLUSION Pretreatment RDW was a special parameter for patients who underwent LPD.It was associated with malnutrition,severe inflammatory status and poorer short-term outcomes.RDW could be a surrogate marker for nutritional and inflammatory status in identifying patients who were at high risk of developing POCs after LPD.展开更多
基金supported by the National Natural Science Foundation of China(12071444,12201581)the Fundamental Research Program of Shanxi Province of China(202103021223191).
文摘The minimal widths of three bounded subsets of the unit sphere associated to a unit vector in a normed linear space are studied,and three related geometric constants are introduced.New characterizations of inner product spaces are also presented.From the perspective of minimal width,strongε-symmetry of Birkhoff orthogonality is introduced,and its relation toε-symmetry of Birkhoff orthogonality is shown.Unlike most of the existing parameters of the underlying space,these new constants are full dimensional in nature.
基金Supported by the National High Technology Research and Development Program of China under Grant No 2014AA041901NSAF Foundation of the National Natural Science Foundation of China under Grant No U1330134+1 种基金the Opening Project of Shanghai Key Laboratory of All Solid-State Laser and Applied Techniques under Grant No 2012ADL02the National Natural Science Foundation of China under Grant Nos 61308024 and 11174305
文摘The wavelength-tunable and switchable narrow bandwidth mode-locking operation is demonstrated in an all fiber laser based on semiconductor-saturable absorber mirror （SESAM）. Two narrow-band fiber Bragg gratings centered at 1029.9nm and 1032nm respectively with a polarization controller inserted between them are used to realize the wavelength switchable between 1029.9nm and 1032nm. The laser delivers different pulse widths of 7.5ps for 1030nm and 20ps for 1032nm. The maximum output power for both could reach -6.5mW at single pulse operation. The output wavelength couM be tuned to about 0.gnm intervals ranging from 1030.2nm to 1031.1 nm and from 1032.15nm to 1033.7nm with the temperature change of the fiber Bragg grating, respectively.
文摘We performed systematic laser spectroscopic investigations of La I spectral lines, using optogalvanic detection. Sixteen previously unknown even parity levels, having energies between 40,300 and 44,300 cm<sup>-1</sup>, are reported. These levels classify altogether 67 lines, not listed in spectral tables. The new levels were found due to the observation of the depopulation of the lower levels of the excited transitions. We found a remarkable variation of the observed widths of single hyperfine structure components dependent on the energy of the upper excited levels. Some levels having energies higher than 43,000 cm<sup>-1</sup> appear to have a very high ionization probability.
基金Supported by the Foundation of Education Department of Yunnan Province (07Z10533)Supported partly by the National Natural Science Foundation of China (10471010)+1 种基金partly by the project "Representation Theory and Related Topics" of the "985 program" of Beijing Normal UniversitySupported by the Science Foundation of Yunnan University (2008YB027)
文摘The article concerns the average onesided widths of the Sobolev and Besov classes and the classes of functions with bounded moduli of smoothness. The weak asymptotic results are obtained for the corresponding quantities.
基金supported by National Natural Science Foundation of China(nos. 11405213,11575236,11275231,11305206)the National Magnetic Confinement Fusion Science Program of China (nos.2013GB107003,2014GB106005,2015GB101000)
文摘The edge plasma code package SOLPS5.0 is employed to simulate the divertor power footprint widths of the experimental advanced superconducting tokamak （EAST） L-mode and ELM-free H-mode plasmas.The divertor power footprint widths,which consist of the scrape-off layer （SOL） width λq and heat spreading S,are important physical parameters for edge plasmas.In this work,a plasma current scan is implemented in the simulation to obtain the dependence of the divertor power footprint width on the plasma current Ip.Strong inverse scaling of the SOL width with Ip has been achieved for both L-mode and H-mode plasmas in the forms of λq,L-mode =4.98 × Ip-0.68 and λq,H-mode =1.86 × Ip-1.08.Similar trends have also been demonstrated in the study of heat spreading with SL-mode =1.95 × Ip-0.542 and SH-mode =0.756 × Ip-0.872.In addition,studies on divertor peak heat load and the magnetic flux expansion factor show that both of them are proportional to plasma current.The simulation work here can act as a way to explore the power footprint widths of future tokamak fusion devices such as ITER and the China Fusion Engineering Test Reactor （CFETR）.
文摘In this paper we study the average σ-K width and the average σ-linear width of the unit ball of l;（R） inl;（R）. The exact values of these widths are calculated and an optimal subspace with the optimal linear opera-tor （for the σ- linear width） are identified.
文摘In this paper,a kind of generalized Sobolev-Wiener classes W_(pq)~y(R,h),h>0,defined on the whole real axis,is introduced,and the average σ-K width problem of these function classes in the metric L_q(R)is studied.For the case p=+∞,1≤q≤+∞,the case 1≤p <+∞,q=1,we get their exact values and identify their optimal subspaces.
文摘A simple rectangular microstrip antenna on low dielectric constant substrate such as air for improved radiation beam performance is theoretically investigated. The conventional patch antenna fabricated on common substrates always produces quite broader E plane pattern compared to its H plane. In the present investigation, the same microstrip antenna is designed on air substrate with a view to develop an efficient feed for parabolic reflector antenna, which shows an excellent radiation pattern with symmetrical 3 dB beam widths at its both E and H plane. The present antenna compared to conventional structure to show its excellence in the beam performance is presented. The complete quantitative analysis to explore such radiation beam characteristics for both the structures (conventional and the present one) is also presented in this paper. An easy and handful relationship between the length of patch antenna and its fringing length for different types of substrate is established in the background of 3 dB beam widths. The proposed idea has been verified through a commercial software package for a patch operating in X band and a concrete physical insight into the phenomenon is developed.
文摘n this paper, the relative widths of some sets in are studied. Relative widths is the further development of Kolmogorov widths and it is a new problem in approximation theory which aroused some mathematics workers great interest recently. We present some basic propositions of relative widths and investigate relative widths of some sets (ball or ellipsoid)
文摘We present the discovery of 18 narrow line Seyfert 1 galaxies (NLS1). The optical spectra show the Balmer lines only slightly broader than the forbidden lines and contain strong Fe Ⅱ emission. No particularly soft X ray spectral slopes can be seen compared to a normal Seyfert 1 galaxies sample.
基金This work was financially supported by the Hunan Valin Lianyuan Iron&Steel Co.,Ltd.,China(No.18H00582).The authors are grateful to Hunan Valin Lianyuan Iron&Steel Co.,Ltd.,China for their assistance with the industrial measurement of velocities near the mold surface.
文摘Computational simulations and high-temperature measurements of velocities near the surface of a mold were carried out by using the rod deflection method to study the effects of various operating parameters on the flow field in slab continuous casting(CC)molds with narrow widths for the production of automobile exposed panels.Reasonable agreement between the calculated results and measured subsurface velocities of liquid steel was obtained under different operating parameters of the CC process.The simulation results reveal that the flow field in the horizontal plane located 50 mm from the meniscus can be used as the characteristic flow field to optimize the flow field of molten steel in the mold.Increases in casting speed can increase the subsurface velocity of molten steel and shift the position of the vortex core downward in the downward circulation zone.The flow field of liquid steel in a 1040 mm-wide slab CC mold can be improved by an Ar gas flow rate of 7 L·min^−1 and casting speed of 1.7 m·min^−1.Under the present experimental conditions,the double-roll flow pattern is generally stable at a submerged entry nozzle immersion depth of 170 mm.
基金supported by National Natural Science Foundation of China(No.11175037)National Natural Science Foundation for Young Scientists of China(No.11305017)Special Fund for Theoretical Physics(No.11247239)
文摘The surface dielectric barrier discharge （SDBD） plasma actuator has shown great promise as an aerodynamic flow control device. In this paper, the encapsulated electrode width of a SDBD actuator is changed to study the airflow acceleration behavior. The effects of encapsulated electrode width on the actuator performance are experimentally investigated by measuring the dielectric layer surface potential, time-averaged ionic wind velocity and thrust force. Experimental results show that the airflow velocity and thrust force increase with the encapsulated electrode width. The results can be attributed to the distinct plasma distribution at different encapsulated electrode widths.
基金supported by the National Natural Science Foundation of China(No.51776220)the Postgraduate Scientific Research Innovation Project of Hunan Province,China。
文摘To investigate the impact of combustor width on continuous rotating detonation(CRD)fueled by ethylene and air,a series of 3 D simulations are conducted by changing the inner cylinder radius of an annular combustor while retaining the same outer cylinder radius.The results show that the CRD wave propagates more steadily and faster as the combustor width increases.The high-temperature zone at the backward-facing step preheats the propellants and contributes to the steady propagation of the CRD wave in 25-and 30-mm wide combustors.The highest and the lowest velocities are obtained in the30-and 15-mm wide combustors at,respectively,1880.27 and 1681.01 m/s.On the other hand,the average thrust decreases as the combustor width increases.The highest thrust is obtained in the 15-mm wide combustor while the lowest is in the 30-mm wide combustor,at 758.06 and 525.93 N,respectively.Nevertheless,the thrust is much more stable in the 25-and 30-mm wide combustors than in the 15-and 20-mm wide combustors.
基金The project is supported partly by the NationalNatural Science Foundation of China(10071007)and partly by the Foundation for University Key Teachers bythe Ministry of Education of China and partly by the Scientific Research Foundation for Returned Ov
文摘This paper concerns the problem of the Kolmogorov n-width, the linear re-width, the Gel'fand n-width and the Bernstein re-width of Sobolev classes of the periodic multivariate functions in the space Lp(Td) and the average Bernstein o-width, average Kolmogorov o-widths, the average linear o-widths of Sobolev classes of the multivariate functions in the space LP(R ), where p = (p1,…,pd), 1 < Pj < ∞o, j = 1,2,…,d, or pj = ∞,j = 1,2,…, d. Their weak asymptotic behaviors are established for the corresponding quantities.
文摘This study was undertaken to examine which factors contributed to the correction of crowding in two patients who underwent nonextraction orthodontic treatment. A study model analysis was conducted to determine the effects of the orthodontic treatment for crowding with high canines on crown angulation and dental arch width in two patients. The results showed that the crown angulation was significantly increased, indicating distal tipping in the maxillary dental arch. This tendency was most commonly observed in the premolars among the lateral teeth. With respect to the dental arch width, the largest change was evident in the first molar and first premolar regions in cases 1 and 2, respectively. On the basis of these results, up-righting of mesially tipped lateral teeth and expansion of narrow dental arches could prove to be the keys to the success of space regaining or correction of high canines and mild crowding.
基金partially supported by National Nature Science Foundation of China(61372187)Sichuan Key Technology Research and Development Program(2012GZ0019,2013GXZ0155)the Fund of Lab of Security Insurance of Cyberspace,Sichuan Province(szjj2014-079)
文摘Probabilistic linear （N, δ）-widths and p-average linear N-widths of Sobolev space W2^r（T）, equipped with a Gaussian probability measure #, are studied in the metric of Sq （T） （1 ≤ Q ≤∞）, and determined the asymptotic equalities：λN,δ（W2^r（T）,μ,Sq（T））={（N^-1）^r＋p/2-1/q√1＋1/N·ln1/δ, 1≤q≤2, （N^-1）^r＋p/2-1/q（1＋N^-1/q√ln1/δ）,2〈q〈∞, （N^-1）^r＋p/2√lnN/δ, q=∞,and λN^（a）（W2^r（T）,μ,Sq（T））p={（N^-1）^r＋p/2-1/q, 1≤q〈∞, （N^-1）^r＋p/2-1/q√lnN, q=∞,where 0 〈 p 〈 ∞, δ∈ （0, 1/2], ρ 〉 1, and Sq（T） is a subspace of L1（T）, in which the Fourier series is absolutely convergent in lq sense.
基金supported by the National Basic Research Program of China(Grant Nos.2013CB933604)the National Natural Science Foundation of China(Grant No.51572290)the Fund from the Chinese Academy of Sciences(Grant Nos.1731300500015 and XDB07030100)
文摘Large-area patterned films of boron nanowires（BNWs） are fabricated at various densities by chemical vapor deposition（CVD）. Different widths of unit-cell of Mo masks are used as templates. The widths of unit-cell of Mo masks are100 μm, 150 μm, and 200 μm, respectively. The distance between unit cells is 50 μm. The BNWs have an average diameter of about 20 nm and lengths of 10 μm–20 μm. High-resolution transmission electron microscopy analysis shows that each nanowire has a β-tetragonal structure with good crystallization. Field emission measurements of the BNW films show that their turn-on electric fields decrease with width of unit-cell increasing.
基金supported by the National Natural Science Foundation of China(42371481)the Beijing Nova Program(20230484302)the Yunnan Provincial Science and Technology Project at Southwest United Graduate School(grant no.202302AO370012).
文摘The power-function exponent b of at-a-station hydraulic geometry(AHG)depicts the temporal response of river hydraulic parameters to changing discharge and is crucial for hydraulic modeling,habitat assessment,and river management.However,previous research,limited by field measurements,offers only a fragmentary understanding of the AHG exponent b in confined areas.Additionally,it remains challenging to establish the correlation between b and the climatic regime of a river.To offer a more comprehensive scope of AHG,this study assesses the width-discharge AHG exponents of 1,568 river reaches by pairing multi-temporal river width data from 1.19 million Landsat images with discharge observations from>17,000 gauge stations worldwide.The results show that b has a median value of 0.213,consistent with values reported in previous regional studies,but it exhibits complex relationships with 3 spatial dimensions-latitude,elevation,and drainage area.We further analyze the spatial variations in b against>200 physiographic and climatic factors,and find that reaches characterized by cohesive soil,high forest coverage,and less anthropogenic influences typically exhibit lower values of b,indicating a weaker response of width to discharge changes.By labeling 4 planimetric river morphologic types globally,we show that braided reaches exhibit the highest median of b,followed by straight,anabranching,and meandering reaches.The differences can be well explained by the climatic conditions of the river reaches as shown on the Budyko curve.This study lays the foundation for AHG research in ungauged regions using satellite remote sensing,expanding global hydraulic data and enhancing the understanding of the spatial variability and influencing factors of hydraulic geometry worldwide.
基金supported by Beijing Natural Science Foundation under Grant L242006.
文摘The four-level nested neutral-point-clamped(4L-NNPC)inverter is a competitive topology among the various medium-voltage multilevel converters,and its main issue is flying-capacitor voltage unbalance.In this article,a novel carrier-interleaved pulse width modulation(CIPWM)method that satisfies the volt-sec balance principle is proposed with an advanced carrier distribution rule.By adopting the proposed CIPWM method,the redundant switching states of 4L-NNPC inverters can be evenly distributed into the output PWM waveform in each carrier period,and natural flying-capacitor voltage balance can be achieved.Furthermore,an active balancing strategy is also proposed to eliminate the voltage unbalance caused by nonideal factors,which is realized by simply adjusting the duty cycle and with no need to adjust the redundant switching states for 4L-NNPC inverters.The simulation and experimental results verify the effectiveness of the proposed CIPWM method and the flying-capacitor voltage balancing strategy.
基金Supported by the National Natural Science Foundation of China,No.81302124.
文摘BACKGROUND Red blood cell distribution width(RDW)is associated with the development and progression of various diseases.AIM To explore the association between pretreatment RDW and short-term outcomes after laparoscopic pancreatoduodenectomy(LPD).METHODS A total of 804 consecutive patients who underwent LPD at our hospital between March 2017 and November 2021 were retrospectively analyzed.Correlations between pretreatment RDW and clinicopathological characteristics and short-term outcomes were investigated.RESULTS Patients with higher pretreatment RDW were older,had higher Eastern Cooperative Oncology Group scores and were associated with poorer short-term outcomes than those with normal RDW.High pretreatment RDW was an independent risk factor for postoperative complications(POCs)(hazard ratio=2.973,95%confidence interval:2.032-4.350,P<0.001)and severe POCs of grade IIIa or higher(hazard ratio=3.138,95%confidence interval:2.042-4.824,P<0.001)based on the Clavien-Dino classification system.Subgroup analysis showed that high pretreatment RDW was an independent risk factor for Clavien-Dino classi-fication grade IIIb or higher POCs,a comprehensive complication index score≥26.2,severe postoperative pancreatic fistula,severe bile leakage and severe hemorrhage.High pretreatment RDW was positively associated with the neutrophil-to-lymphocyte ratio and platelet-to-lymphocyte ratio and was negatively associated with albumin and the prognostic nutritional index.CONCLUSION Pretreatment RDW was a special parameter for patients who underwent LPD.It was associated with malnutrition,severe inflammatory status and poorer short-term outcomes.RDW could be a surrogate marker for nutritional and inflammatory status in identifying patients who were at high risk of developing POCs after LPD.
