AIM:To investigate the binocular intraocular lens(IOL)power difference in eyes with short,normal,and long axial lengths(AL)using Lenstar LS 900 optical biometry.METHODS:A total of 716(1432 eyes)participants were inclu...AIM:To investigate the binocular intraocular lens(IOL)power difference in eyes with short,normal,and long axial lengths(AL)using Lenstar LS 900 optical biometry.METHODS:A total of 716(1432 eyes)participants were included.The groups were categorized into short(group A:AL<22 mm),normal(group B:22 mm≤AL≤25 mm),and long AL groups(group C:AL>25 mm).The central corneal thickness(CCT),anterior chamber depth(ACD),lens thickness(LT),AL,anterior corneal keratometry,whiteto-white(WTW),pupil diameter(PD),as well as IOL power calculated using embedded Barrett formula were assessed.Bland-Altman plots were used to test the agreement of the binocular parameters.RESULTS:In group A,the CCT of the right eye was significantly thinner than that of the left eye(P=0.044)with a difference of-2±8μm[95%limits of agreement(LoA),-17.8 to 13.2μm].For group B,the PD and IOL power in the right eye were significantly lower than those of the left eye(P=0.001,<0.001)with a difference of-0.05±0.32 mm(95%LoA,-0.68 to 0.58 mm)and-0.18±1.01 D(95%LoA,-2.2 to 1.8 D).The AL of right eye was longer than that of the left eye(P=0.002)with a difference of 0.04±0.25 mm(95%Lo A,-0.45 to 0.52 mm).No significant difference was observed for all the binocular parameters in group C.The percentage of participants with binocular IOL power difference within±0.5 D were 62%(31/50),68.3%(339/496),and 38.8%(66/170)in groups A,B,and C,respectively.CONCLUSION:The binocular parameters related to IOL power are in good agreement,but the binocular IOL power difference of more than half of participants with long AL is more than 0.50 D.展开更多
In this study,experimental and numerical simulation methods were combined to simulate the changing course of the temperature and velocity fields in nine different fire scenes. The characteristics of smoke movement in ...In this study,experimental and numerical simulation methods were combined to simulate the changing course of the temperature and velocity fields in nine different fire scenes. The characteristics of smoke movement in shafts with different fire source position factors(h/H) were quantitatively investigated,and the non-dimensional fitting function between the fire source position factors and the maximum temperature was deduced. The results showed that the location of the neutral plane moved upward as the fire source rose,and all the generated smoke spread to the upper areas;however,there was barely any smoke in the lower areas. The maximum temperature was inversely proportional to the fire source position factor;the higher the source position is,i.e. the higher the ratio factor is,the lower the maximum temperature is in the shaft. The experimental verification of the fire dynamics simulator(FDS) showed good results.展开更多
In this work, by controlling the positional relationship between the target and the focal point, the surface damage, shock wave phenomenon and propagation mechanism involved in the plasma generation of fused silica by...In this work, by controlling the positional relationship between the target and the focal point, the surface damage, shock wave phenomenon and propagation mechanism involved in the plasma generation of fused silica by millisecond pulsed laser irradiation at different focal positions were studied. Laser energy is an important experimental variable. The dynamic process of plasma was detected by optical shadow method, and the influence of surface film damage on plasma propagation and the propagation mechanism at different focal positions were discussed. The study found that the plasma induced by the pulsed laser at the focus position within 0–20 μs exploded, the micro-droplets formed around 20 μs. At the same time, a shock wave is formed by the compressed air, the micro-droplets are compressed under the action of the shock wave recoil pressure, and the micro-droplets channel phenomenon is observed in the micro-droplets. The peak velocities of plasma and combustion wave appear earlier in the pre-focus position than in the post-focus position. This research provides a reference for the field of laser processing using fused silica as the substrate.展开更多
The densification and the fractal dimensions of carbon-nickel films annealed at different temperatures 300, 500, 800, and 1000℃ with emphasis on porosity evaluation are investigated. For this purpose, the refractive...The densification and the fractal dimensions of carbon-nickel films annealed at different temperatures 300, 500, 800, and 1000℃ with emphasis on porosity evaluation are investigated. For this purpose, the refractive index of films is determined from transmittance spectra. Three different regimes are identified, T 〈 500℃, 500℃ 〈 T 〈 800℃ and T 〉 800℃. The Rutherford baekscattering spectra show that with increasing the annealing temperature, the concentration of nickel atoms into films decreases. It is shown that the effect of annealing temperatures for increasing films densification at T 〈 500℃ and T 〉 800℃ is greater than the effect of nickel concentrations. It is observed that the effect of decreasing nickel atoms into films at 500℃ 〈 T 〈 800℃ strongly causes improving porosity and decreasing densification. The fractal dimensions of carbon-nickel films annealed from 300 to 500℃ are increased, while from 500 to 1000℃ these characteristics are decreased. It can be seen that at 800℃, films have maximum values of porosity and roughness.展开更多
The stable coordinated metallo-complexes based on 2,2′:6′,2″-terpyridine(tpy)and its derivatives have been widely researched for various wide-ranging applications in photoelectronics,catalysis,sensor,photoluminesce...The stable coordinated metallo-complexes based on 2,2′:6′,2″-terpyridine(tpy)and its derivatives have been widely researched for various wide-ranging applications in photoelectronics,catalysis,sensor,photoluminescence,and so on.However,the most reported studies ignored the comprehensive comparison between structures modified by different positions and photoluminescence.Herein,we design a series of metallo-complexes which were assembled with tpy substituted triphenylamine(TPA)at different positions and metal ions and explored their photophysical properties.In the solution state,MLE_(2)based on the 5,5″-positions modification showed the highest PLQYs and PL intensity.With the increase of solvent polarity,MLB2exhibit the largest redshift.In the solid state,from MLA_(2)to MLE_(2),the emission colours are gradually red-shifted from yellow to red.The findings in this work may pave a new way to design functional metallo-complexes,not just for PL properties.展开更多
This paper describes systematic measurement of fiber migration and distribution pattern of twist at different radial positions of rotor spun yarn mixed tracer fiber by Hi-Scope Video Microscope System. The positions o...This paper describes systematic measurement of fiber migration and distribution pattern of twist at different radial positions of rotor spun yarn mixed tracer fiber by Hi-Scope Video Microscope System. The positions of tracer fibers were measured in three dimensions accurately, and the migration index and the twist distribution at different radial positions of rotor yarn were calculated and analyzed. This research result serves to provide useful references for further study on the structural mechanics of rotor spun yarn.展开更多
Iron ore sintering is a pre-treatment technology by which orefines are converted into porous and permeable sin-ters,which are the used in blast furnaces.This process can be adversely affected by air leakage phenomena ...Iron ore sintering is a pre-treatment technology by which orefines are converted into porous and permeable sin-ters,which are the used in blast furnaces.This process can be adversely affected by air leakage phenomena of various types.As experimental measurements are relatively difficult and often scarcely reliable,here a theoretical model based on typicalfluid-dynamic concepts and relationships is elaborated.Through the analysis of two extreme cases,namely,those in which leakage is due to a small hole or a full rupture,a generalized hole-bed mod-el is introduced,which for thefirst time also includes a complete bed permeability equation and can deal with different leakage position conditions.The results show that the model can evaluate the influence of leakage on the system at one time and be used to calculate theflowrate and pressure drop.Notably,the obtained results are within a 15%deviation with respect to available experiment values,used for comparison.展开更多
To achieve the goals of carbon peaking and carbon neutrality and maintain high-quality economic growth,China is currently striving to improve the quality of development of its power sector.In this regard,revealing the...To achieve the goals of carbon peaking and carbon neutrality and maintain high-quality economic growth,China is currently striving to improve the quality of development of its power sector.In this regard,revealing the regional differences and evolutionary trends in the development quality of China’power sector has a high value to inspire the next improvement direction toward how to integrate regional power recourses to an overall optimization level.Motived by this purpose,this paper uses the entropy method to evaluate the com‐prehensive and subsystem indices of the development quality of the power industry,and reveals their re‐gional differences and evolutionary trends with the help of the Dagum Gini coefficient and Kernel density es‐timation methods.The findings show that:There are obvious regional differences in the development quality of China’s power industry,and the differences are steadily declining in all regions except the West.Regional differences are mainly derived from inter-regional differences,with the largest inter-regional differences in the East-Northeast region.Intra-regional differences show a distribution pattern of East>West>North‐east>Center.展开更多
Fire rescue challenges and solutions have evolved from straightfor-ward plane rescue to encompass 3D space due to the rise of high-rise city buildings.Hence,this study facilitates a system with quick and simplified on...Fire rescue challenges and solutions have evolved from straightfor-ward plane rescue to encompass 3D space due to the rise of high-rise city buildings.Hence,this study facilitates a system with quick and simplified on-site launching and generates real-time location data,enabling fire rescuers to arrive at the intended spot faster and correctly for effective and precise rescue.Auto-positioning with step-by-step instructions is proposed when launching the locating system,while no extra measuring instrument like Total Station(TS)is needed.Real-time location tracking is provided via a 3D space real-time locating system(RTLS)constructed using Ultra-wide Bandwidth technology(UWB),which requires electromagnetic waves to pass through concrete walls.A hybrid weighted least squares with a time difference of arrival(WLS/TDOA)positioning method is proposed to address real path-tracking issues in 3D space and to meet RTLS requirements for quick computing in real-world applications.The 3D WLS/TDOA algorithm is theoretically constructed with the Cramer-Rao lower bound(CRLB).The computing complexity is reduced to the lower bound for embedded hardware to directly compute the time differential of the arriving signals using the time-to-digital converter(TDC).The results of the experiments show that the errors are controlled when the positioning algorithm is applied in various complicated situations to fulfill the requirements of engineering applications.The statistical analysis of the data reveals that the proposed UWB RTLS auto-positioning system can track target tags with an accuracy of 0.20 m.展开更多
As an essential infrastructure,the rural power grid is vital in promoting agricultural and rural carbon sequestration and improving rural energy electrification.It is necessary to carry out in-depth research on its co...As an essential infrastructure,the rural power grid is vital in promoting agricultural and rural carbon sequestration and improving rural energy electrification.It is necessary to carry out in-depth research on its comprehensive efficiency.Based on the requirements of“double carbon”and rural revitalization strategy for the rural Power Grid,this paper focuses on the modernization and low-carbon transformation of the rural Power Grid.It constructs an input-output index system for the investment efficiency of the rural Power Grid in China under the new situation.It uses the primary data of the rural Power Grid of 30 prefecture-level cities in China from 2019 to 2021 to evaluate the investment efficiency of the rural Power Grid in China through a three-stage DEA model.The empirical results show that:considering the regional differences,the comprehensive efficiency of the rural Power Grid in backward areas is significantly improved;that is,the three-stage DEA method can more objectively evaluate the comprehensive efficiency of the rural Power Grid.In the context of the continued promotion of the rural revitalization strategy,to improve the comprehensive efficiency of the rural Power Grid,it is necessary to improve the technical level of the rural Power Grid further and appropriately expand the scale of investment in the rural Power Grid.展开更多
Consider the first order neutral delay differential equation with positive and negative coefficients:[x(t)-c(t)x(t-γ)]+p(t)x(t-τ)-Q(t)x(t-δ)=0,t≥t 0,(1)where c,p,Q∈C((t 0,∞),R +),R +=(0,∞),γ】0,t】δ≥0. W...Consider the first order neutral delay differential equation with positive and negative coefficients:[x(t)-c(t)x(t-γ)]+p(t)x(t-τ)-Q(t)x(t-δ)=0,t≥t 0,(1)where c,p,Q∈C((t 0,∞),R +),R +=(0,∞),γ】0,t】δ≥0. We obtain the sufficient condition for the existence of positive solutions of Eq.(1). As a corollary, we improve the correspondent result in by removing the condition∫ ∞ c 0 (t) d t=∞,where (t)=p(t)-Q(t-τ+δ)≥0.展开更多
Objective To explore the differences in three different registration methods of cone beam computed tomography(CBCT)-guided down-regulated intense radiation therapy for lung cancer as well as the effects of tumor locat...Objective To explore the differences in three different registration methods of cone beam computed tomography(CBCT)-guided down-regulated intense radiation therapy for lung cancer as well as the effects of tumor location,treatment mode,and tumor size on registration.Methods This retrospective analysis included 80 lung cancer patients undergoing radiotherapy in our hospital from November 2017 to October 2019 and compared automatic bone registration,automatic grayscale(t+r)registration,and automatic grayscale(t)positioning error on the X-,Y-,and Z-axes under three types of registration methods.The patients were also grouped according to tumor position,treatment mode,and tumor size to compare positioning errors.Results On the X-,Y-,and Z-axes,automatic grayscale(t+r)and automatic grayscale(t)registration showed a better trend.Analysis of the different treatment modes showed differences in the three registration methods;however,these were not statistically significant.Analysis according to tumor sizes showed significant differences between the three registration methods(P<0.05).Analysis according to tumor positions showed differences in the X-and Y-axes that were not significant(P>0.05),while the autopsy registration in the Z-axis showed the largest difference in the mediastinal and hilar lymph nodes(P<0.05).Conclusion The treatment mode was not the main factor affecting registration error in lung cancer.Three registration methods are available for tumors in the upper and lower lungs measuring<3 cm;among these,automatic gray registration is recommended,while any gray registration method is recommended for tumors located in the mediastinal hilar site measuring<3 cm and in the upper and lower lungs≥3 cm.展开更多
Over the past decades,quite a lot of scholars both in and out of China have dedicated themselves to the research of body language and a great number of works have been published to give impetus to the study of body la...Over the past decades,quite a lot of scholars both in and out of China have dedicated themselves to the research of body language and a great number of works have been published to give impetus to the study of body language.The paper aims to study the differences of body language in China and America from the perspective of power distance to help people from different cultural backgrounds achieve a successful intercultural communication and avoid conflict as much as possible.展开更多
In this paper we propose a simple evolving network with link additions as well as removals. The preferential attachment of link additions is similar to BA model’s, while the removal rule is newly added. From the pers...In this paper we propose a simple evolving network with link additions as well as removals. The preferential attachment of link additions is similar to BA model’s, while the removal rule is newly added. From the perspective of Markov chain, we give the exact solution of the degree distribution and show that whether the network is scale-free or not depends on the parameter m, and the degree exponent varying in (3, 5] is also depend on m if scale-free.展开更多
The main harmonic components in nonlinear differential equations can be solved by using the harmonic balance principle. The nonlinear coupling relation among various harmonics can be found by balance theorem of freque...The main harmonic components in nonlinear differential equations can be solved by using the harmonic balance principle. The nonlinear coupling relation among various harmonics can be found by balance theorem of frequency domain. The superhet receiver circuits which are described by nonlinear differential equation of comprising even degree terms include three main harmonic components: the difference frequency and two signal frequencies. Based on the nonlinear coupling relation, taking superhet circuit as an example, this paper demonstrates that the every one of three main harmonics in networks must individually observe conservation of complex power. The power of difference frequency is from variable-frequency device. And total dissipative power of each harmonic is equal to zero. These conclusions can also be verified by the traditional harmonic analysis. The oscillation solutions which consist of the mixture of three main harmonics possess very long oscillation period, the spectral distribution are very tight, similar to evolution from doubling period leading to chaos. It can be illustrated that the chaos is sufficient or infinite extension of the oscillation period. In fact, the oscillation solutions plotted by numerical simulation all are certainly a periodic function of discrete spectrum. When phase portrait plotted hasn’t finished one cycle, it is shown as aperiodic chaos.展开更多
Tarnavas established mixed weighted power mean inequality in 1999. A separation of weighted power mean inequslity was derived in this paper. As its applications, some separations of other inequalities were given.
Based on the measurement of one-dimensional (1D) optical path difference (OPD) of the supersonic turbulent bound- ary layer, an analytical form for the power spectrum of the two-dimensional (2D) OPD is obtained ...Based on the measurement of one-dimensional (1D) optical path difference (OPD) of the supersonic turbulent bound- ary layer, an analytical form for the power spectrum of the two-dimensional (2D) OPD is obtained with its structure function and under the locally homogeneous isotropic assumption. The universality of this spectrum is argued, and its validity is checked by the comparison with experimental result. The potential applications of this model in theoretical and numerical studies are emphasized. Another contribution of this work is around the application of correlation function to analyzing the statistics of OPD. Based on our results and other results published elsewhere, we show that the OPD is often not stationary, and one should be cautious about using this tool.展开更多
Purpose: Long-term training specificity is thought to alter performance in tests evaluating strength and power production capability. The aim of the present study was to provide additional information to the limited ...Purpose: Long-term training specificity is thought to alter performance in tests evaluating strength and power production capability. The aim of the present study was to provide additional information to the limited existing knowledge concerning the possible differences of the force/time profile of squat jumping among different groups of young female athletes. Methods: One hundred and seventy-three adult women (20.1 ± 2.8 years, 1.71 ± 0.09 m, 65.6 ± 10.3 kg, mean± SD for age, height, and mass, respectively) engaged in track and field (TF), volleyball (VO), handball (HA), basketball (BA), and physical education students (PE) executed maximal squat jumps (SQJ) on a force plate. Pearson's correlation was used to identify the relationship between SQJ performance, the anthropometric characteristics and the biomechanical parameters. Differences concerning the biomechanical parameters among groups were investigated with analysis of variance, while the force- (FPD) or time- (TPD) dependency of SQJ execution was examined using principal components analysis (PCA). Results: SQJ was unrelated to body height but significantly correlated with body mass (r = -0.26, p = 0.001). TF jumped higher and produced larger peak body power output compared to all the other groups (p 〈 0.05). All athletes were superior to PE since they performed the SQJ with a longer (p 〈 0.05) vertical body center of mass trajectory during the propulsion phase. PCA results revealed that TF significantly differentiated than the other groups by relying on FPD. Conclusion: Various different profiles of FPD and TPD were detected due to different sporting background in young female athletes. Since TF superiority in SQJ was relied on the larger power production and a greater FPD, female indoor team sport athletes are suggested to execute jumping exercises adopting the jumping strategies utilized by TE展开更多
The conventional direct position determination(DPD) algorithm processes all received signals on a single sensor.When sensors have limited computational capabilities or energy storage,it is desirable to distribute th...The conventional direct position determination(DPD) algorithm processes all received signals on a single sensor.When sensors have limited computational capabilities or energy storage,it is desirable to distribute the computation among other sensors.A distributed adaptive DPD(DADPD)algorithm based on diffusion framework is proposed for emitter localization.Unlike the corresponding centralized adaptive DPD(CADPD) algorithm,all but one sensor in the proposed algorithm participate in processing the received signals and estimating the common emitter position,respectively.The computational load and energy consumption on a single sensor in the CADPD algorithm is distributed among other computing sensors in a balanced manner.Exactly the same iterative localization algorithm is carried out in each computing sensor,respectively,and the algorithm in each computing sensor exhibits quite similar convergence behavior.The difference of the localization and tracking performance between the proposed distributed algorithm and the corresponding CADPD algorithm is negligible through simulation evaluations.展开更多
The two-station positioning system based on time difference and azimuth measurement has measurement redundancy. Therefore, not only can a positioning solution which is completely independent of the baseline length bet...The two-station positioning system based on time difference and azimuth measurement has measurement redundancy. Therefore, not only can a positioning solution which is completely independent of the baseline length between two stations be derived, but also the baseline length can be solved as an unknown quantity. These findings not only enhance the performance of the two-station positioning system, but also provide a design basis for the construction of a self-organizing dynamic intelligent positioning system.展开更多
基金Supported by the National Natural Science Foundation of China(No.81971697No.81501544)+1 种基金Shanxi Scholarship Council of China(No.2021-174)the Research Funding of Shanxi Eye Hospital(No.B201804)。
文摘AIM:To investigate the binocular intraocular lens(IOL)power difference in eyes with short,normal,and long axial lengths(AL)using Lenstar LS 900 optical biometry.METHODS:A total of 716(1432 eyes)participants were included.The groups were categorized into short(group A:AL<22 mm),normal(group B:22 mm≤AL≤25 mm),and long AL groups(group C:AL>25 mm).The central corneal thickness(CCT),anterior chamber depth(ACD),lens thickness(LT),AL,anterior corneal keratometry,whiteto-white(WTW),pupil diameter(PD),as well as IOL power calculated using embedded Barrett formula were assessed.Bland-Altman plots were used to test the agreement of the binocular parameters.RESULTS:In group A,the CCT of the right eye was significantly thinner than that of the left eye(P=0.044)with a difference of-2±8μm[95%limits of agreement(LoA),-17.8 to 13.2μm].For group B,the PD and IOL power in the right eye were significantly lower than those of the left eye(P=0.001,<0.001)with a difference of-0.05±0.32 mm(95%LoA,-0.68 to 0.58 mm)and-0.18±1.01 D(95%LoA,-2.2 to 1.8 D).The AL of right eye was longer than that of the left eye(P=0.002)with a difference of 0.04±0.25 mm(95%Lo A,-0.45 to 0.52 mm).No significant difference was observed for all the binocular parameters in group C.The percentage of participants with binocular IOL power difference within±0.5 D were 62%(31/50),68.3%(339/496),and 38.8%(66/170)in groups A,B,and C,respectively.CONCLUSION:The binocular parameters related to IOL power are in good agreement,but the binocular IOL power difference of more than half of participants with long AL is more than 0.50 D.
文摘In this study,experimental and numerical simulation methods were combined to simulate the changing course of the temperature and velocity fields in nine different fire scenes. The characteristics of smoke movement in shafts with different fire source position factors(h/H) were quantitatively investigated,and the non-dimensional fitting function between the fire source position factors and the maximum temperature was deduced. The results showed that the location of the neutral plane moved upward as the fire source rose,and all the generated smoke spread to the upper areas;however,there was barely any smoke in the lower areas. The maximum temperature was inversely proportional to the fire source position factor;the higher the source position is,i.e. the higher the ratio factor is,the lower the maximum temperature is in the shaft. The experimental verification of the fire dynamics simulator(FDS) showed good results.
基金supported by Natural Science Foundation of Jilin Province,China(No.20220101032JC)。
文摘In this work, by controlling the positional relationship between the target and the focal point, the surface damage, shock wave phenomenon and propagation mechanism involved in the plasma generation of fused silica by millisecond pulsed laser irradiation at different focal positions were studied. Laser energy is an important experimental variable. The dynamic process of plasma was detected by optical shadow method, and the influence of surface film damage on plasma propagation and the propagation mechanism at different focal positions were discussed. The study found that the plasma induced by the pulsed laser at the focus position within 0–20 μs exploded, the micro-droplets formed around 20 μs. At the same time, a shock wave is formed by the compressed air, the micro-droplets are compressed under the action of the shock wave recoil pressure, and the micro-droplets channel phenomenon is observed in the micro-droplets. The peak velocities of plasma and combustion wave appear earlier in the pre-focus position than in the post-focus position. This research provides a reference for the field of laser processing using fused silica as the substrate.
文摘The densification and the fractal dimensions of carbon-nickel films annealed at different temperatures 300, 500, 800, and 1000℃ with emphasis on porosity evaluation are investigated. For this purpose, the refractive index of films is determined from transmittance spectra. Three different regimes are identified, T 〈 500℃, 500℃ 〈 T 〈 800℃ and T 〉 800℃. The Rutherford baekscattering spectra show that with increasing the annealing temperature, the concentration of nickel atoms into films decreases. It is shown that the effect of annealing temperatures for increasing films densification at T 〈 500℃ and T 〉 800℃ is greater than the effect of nickel concentrations. It is observed that the effect of decreasing nickel atoms into films at 500℃ 〈 T 〈 800℃ strongly causes improving porosity and decreasing densification. The fractal dimensions of carbon-nickel films annealed from 300 to 500℃ are increased, while from 500 to 1000℃ these characteristics are decreased. It can be seen that at 800℃, films have maximum values of porosity and roughness.
基金financially supported by the National Natural Science Foundation of China(Nos.22271116 and 22071079 for M.W)Jilin Provincial Science and Technology Department(No.20230101027JC for M.W.)the fellowship of China Postdoctoral Science Foundation(No.2021M701383 for J.S)。
文摘The stable coordinated metallo-complexes based on 2,2′:6′,2″-terpyridine(tpy)and its derivatives have been widely researched for various wide-ranging applications in photoelectronics,catalysis,sensor,photoluminescence,and so on.However,the most reported studies ignored the comprehensive comparison between structures modified by different positions and photoluminescence.Herein,we design a series of metallo-complexes which were assembled with tpy substituted triphenylamine(TPA)at different positions and metal ions and explored their photophysical properties.In the solution state,MLE_(2)based on the 5,5″-positions modification showed the highest PLQYs and PL intensity.With the increase of solvent polarity,MLB2exhibit the largest redshift.In the solid state,from MLA_(2)to MLE_(2),the emission colours are gradually red-shifted from yellow to red.The findings in this work may pave a new way to design functional metallo-complexes,not just for PL properties.
文摘This paper describes systematic measurement of fiber migration and distribution pattern of twist at different radial positions of rotor spun yarn mixed tracer fiber by Hi-Scope Video Microscope System. The positions of tracer fibers were measured in three dimensions accurately, and the migration index and the twist distribution at different radial positions of rotor yarn were calculated and analyzed. This research result serves to provide useful references for further study on the structural mechanics of rotor spun yarn.
文摘Iron ore sintering is a pre-treatment technology by which orefines are converted into porous and permeable sin-ters,which are the used in blast furnaces.This process can be adversely affected by air leakage phenomena of various types.As experimental measurements are relatively difficult and often scarcely reliable,here a theoretical model based on typicalfluid-dynamic concepts and relationships is elaborated.Through the analysis of two extreme cases,namely,those in which leakage is due to a small hole or a full rupture,a generalized hole-bed mod-el is introduced,which for thefirst time also includes a complete bed permeability equation and can deal with different leakage position conditions.The results show that the model can evaluate the influence of leakage on the system at one time and be used to calculate theflowrate and pressure drop.Notably,the obtained results are within a 15%deviation with respect to available experiment values,used for comparison.
基金supported by National Natural Science Foundation of China[Grant number.71673034]Postdoctoral Research Founda‐tion of China[Grant number.2021M692654]+1 种基金Natural Science Basic Research Program of Shaanxi Province[Grant number.2020JQ282]Social Science Foundation of Shaanxi Province[Grant number.2020R042].
文摘To achieve the goals of carbon peaking and carbon neutrality and maintain high-quality economic growth,China is currently striving to improve the quality of development of its power sector.In this regard,revealing the regional differences and evolutionary trends in the development quality of China’power sector has a high value to inspire the next improvement direction toward how to integrate regional power recourses to an overall optimization level.Motived by this purpose,this paper uses the entropy method to evaluate the com‐prehensive and subsystem indices of the development quality of the power industry,and reveals their re‐gional differences and evolutionary trends with the help of the Dagum Gini coefficient and Kernel density es‐timation methods.The findings show that:There are obvious regional differences in the development quality of China’s power industry,and the differences are steadily declining in all regions except the West.Regional differences are mainly derived from inter-regional differences,with the largest inter-regional differences in the East-Northeast region.Intra-regional differences show a distribution pattern of East>West>North‐east>Center.
文摘Fire rescue challenges and solutions have evolved from straightfor-ward plane rescue to encompass 3D space due to the rise of high-rise city buildings.Hence,this study facilitates a system with quick and simplified on-site launching and generates real-time location data,enabling fire rescuers to arrive at the intended spot faster and correctly for effective and precise rescue.Auto-positioning with step-by-step instructions is proposed when launching the locating system,while no extra measuring instrument like Total Station(TS)is needed.Real-time location tracking is provided via a 3D space real-time locating system(RTLS)constructed using Ultra-wide Bandwidth technology(UWB),which requires electromagnetic waves to pass through concrete walls.A hybrid weighted least squares with a time difference of arrival(WLS/TDOA)positioning method is proposed to address real path-tracking issues in 3D space and to meet RTLS requirements for quick computing in real-world applications.The 3D WLS/TDOA algorithm is theoretically constructed with the Cramer-Rao lower bound(CRLB).The computing complexity is reduced to the lower bound for embedded hardware to directly compute the time differential of the arriving signals using the time-to-digital converter(TDC).The results of the experiments show that the errors are controlled when the positioning algorithm is applied in various complicated situations to fulfill the requirements of engineering applications.The statistical analysis of the data reveals that the proposed UWB RTLS auto-positioning system can track target tags with an accuracy of 0.20 m.
基金supported by the State Grid Science and Technology Project (1300-202157362A-0-0-00).
文摘As an essential infrastructure,the rural power grid is vital in promoting agricultural and rural carbon sequestration and improving rural energy electrification.It is necessary to carry out in-depth research on its comprehensive efficiency.Based on the requirements of“double carbon”and rural revitalization strategy for the rural Power Grid,this paper focuses on the modernization and low-carbon transformation of the rural Power Grid.It constructs an input-output index system for the investment efficiency of the rural Power Grid in China under the new situation.It uses the primary data of the rural Power Grid of 30 prefecture-level cities in China from 2019 to 2021 to evaluate the investment efficiency of the rural Power Grid in China through a three-stage DEA model.The empirical results show that:considering the regional differences,the comprehensive efficiency of the rural Power Grid in backward areas is significantly improved;that is,the three-stage DEA method can more objectively evaluate the comprehensive efficiency of the rural Power Grid.In the context of the continued promotion of the rural revitalization strategy,to improve the comprehensive efficiency of the rural Power Grid,it is necessary to improve the technical level of the rural Power Grid further and appropriately expand the scale of investment in the rural Power Grid.
文摘Consider the first order neutral delay differential equation with positive and negative coefficients:[x(t)-c(t)x(t-γ)]+p(t)x(t-τ)-Q(t)x(t-δ)=0,t≥t 0,(1)where c,p,Q∈C((t 0,∞),R +),R +=(0,∞),γ】0,t】δ≥0. We obtain the sufficient condition for the existence of positive solutions of Eq.(1). As a corollary, we improve the correspondent result in by removing the condition∫ ∞ c 0 (t) d t=∞,where (t)=p(t)-Q(t-τ+δ)≥0.
基金Supported by grants from the Nanchong City School Cooperation Project(No.18SXHZ0542)Hubei Chen Xiaoping Science and Technology Development Foundation Project(No.CXPJJH11900002-037)Sichuan Medical Research Youth Innovation Project(No.Q18031).
文摘Objective To explore the differences in three different registration methods of cone beam computed tomography(CBCT)-guided down-regulated intense radiation therapy for lung cancer as well as the effects of tumor location,treatment mode,and tumor size on registration.Methods This retrospective analysis included 80 lung cancer patients undergoing radiotherapy in our hospital from November 2017 to October 2019 and compared automatic bone registration,automatic grayscale(t+r)registration,and automatic grayscale(t)positioning error on the X-,Y-,and Z-axes under three types of registration methods.The patients were also grouped according to tumor position,treatment mode,and tumor size to compare positioning errors.Results On the X-,Y-,and Z-axes,automatic grayscale(t+r)and automatic grayscale(t)registration showed a better trend.Analysis of the different treatment modes showed differences in the three registration methods;however,these were not statistically significant.Analysis according to tumor sizes showed significant differences between the three registration methods(P<0.05).Analysis according to tumor positions showed differences in the X-and Y-axes that were not significant(P>0.05),while the autopsy registration in the Z-axis showed the largest difference in the mediastinal and hilar lymph nodes(P<0.05).Conclusion The treatment mode was not the main factor affecting registration error in lung cancer.Three registration methods are available for tumors in the upper and lower lungs measuring<3 cm;among these,automatic gray registration is recommended,while any gray registration method is recommended for tumors located in the mediastinal hilar site measuring<3 cm and in the upper and lower lungs≥3 cm.
文摘Over the past decades,quite a lot of scholars both in and out of China have dedicated themselves to the research of body language and a great number of works have been published to give impetus to the study of body language.The paper aims to study the differences of body language in China and America from the perspective of power distance to help people from different cultural backgrounds achieve a successful intercultural communication and avoid conflict as much as possible.
基金supported by the National Natural Science Foundation of China (10671212)Research Fund for the Doctoral Program of Higher Education of China (20050533036)
文摘In this paper we propose a simple evolving network with link additions as well as removals. The preferential attachment of link additions is similar to BA model’s, while the removal rule is newly added. From the perspective of Markov chain, we give the exact solution of the degree distribution and show that whether the network is scale-free or not depends on the parameter m, and the degree exponent varying in (3, 5] is also depend on m if scale-free.
文摘The main harmonic components in nonlinear differential equations can be solved by using the harmonic balance principle. The nonlinear coupling relation among various harmonics can be found by balance theorem of frequency domain. The superhet receiver circuits which are described by nonlinear differential equation of comprising even degree terms include three main harmonic components: the difference frequency and two signal frequencies. Based on the nonlinear coupling relation, taking superhet circuit as an example, this paper demonstrates that the every one of three main harmonics in networks must individually observe conservation of complex power. The power of difference frequency is from variable-frequency device. And total dissipative power of each harmonic is equal to zero. These conclusions can also be verified by the traditional harmonic analysis. The oscillation solutions which consist of the mixture of three main harmonics possess very long oscillation period, the spectral distribution are very tight, similar to evolution from doubling period leading to chaos. It can be illustrated that the chaos is sufficient or infinite extension of the oscillation period. In fact, the oscillation solutions plotted by numerical simulation all are certainly a periodic function of discrete spectrum. When phase portrait plotted hasn’t finished one cycle, it is shown as aperiodic chaos.
基金Project supported by National Natural Science Foundation of China (Grant No. 10271071)
文摘Tarnavas established mixed weighted power mean inequality in 1999. A separation of weighted power mean inequslity was derived in this paper. As its applications, some separations of other inequalities were given.
基金Project supported by the National Natural Science Foundation of China(Grant No.61008037)the National Basic Research Program of China(Grant No.2009CB724100)
文摘Based on the measurement of one-dimensional (1D) optical path difference (OPD) of the supersonic turbulent bound- ary layer, an analytical form for the power spectrum of the two-dimensional (2D) OPD is obtained with its structure function and under the locally homogeneous isotropic assumption. The universality of this spectrum is argued, and its validity is checked by the comparison with experimental result. The potential applications of this model in theoretical and numerical studies are emphasized. Another contribution of this work is around the application of correlation function to analyzing the statistics of OPD. Based on our results and other results published elsewhere, we show that the OPD is often not stationary, and one should be cautious about using this tool.
文摘Purpose: Long-term training specificity is thought to alter performance in tests evaluating strength and power production capability. The aim of the present study was to provide additional information to the limited existing knowledge concerning the possible differences of the force/time profile of squat jumping among different groups of young female athletes. Methods: One hundred and seventy-three adult women (20.1 ± 2.8 years, 1.71 ± 0.09 m, 65.6 ± 10.3 kg, mean± SD for age, height, and mass, respectively) engaged in track and field (TF), volleyball (VO), handball (HA), basketball (BA), and physical education students (PE) executed maximal squat jumps (SQJ) on a force plate. Pearson's correlation was used to identify the relationship between SQJ performance, the anthropometric characteristics and the biomechanical parameters. Differences concerning the biomechanical parameters among groups were investigated with analysis of variance, while the force- (FPD) or time- (TPD) dependency of SQJ execution was examined using principal components analysis (PCA). Results: SQJ was unrelated to body height but significantly correlated with body mass (r = -0.26, p = 0.001). TF jumped higher and produced larger peak body power output compared to all the other groups (p 〈 0.05). All athletes were superior to PE since they performed the SQJ with a longer (p 〈 0.05) vertical body center of mass trajectory during the propulsion phase. PCA results revealed that TF significantly differentiated than the other groups by relying on FPD. Conclusion: Various different profiles of FPD and TPD were detected due to different sporting background in young female athletes. Since TF superiority in SQJ was relied on the larger power production and a greater FPD, female indoor team sport athletes are suggested to execute jumping exercises adopting the jumping strategies utilized by TE
基金supported by the National Natural Science Foundation of China(61101173)
文摘The conventional direct position determination(DPD) algorithm processes all received signals on a single sensor.When sensors have limited computational capabilities or energy storage,it is desirable to distribute the computation among other sensors.A distributed adaptive DPD(DADPD)algorithm based on diffusion framework is proposed for emitter localization.Unlike the corresponding centralized adaptive DPD(CADPD) algorithm,all but one sensor in the proposed algorithm participate in processing the received signals and estimating the common emitter position,respectively.The computational load and energy consumption on a single sensor in the CADPD algorithm is distributed among other computing sensors in a balanced manner.Exactly the same iterative localization algorithm is carried out in each computing sensor,respectively,and the algorithm in each computing sensor exhibits quite similar convergence behavior.The difference of the localization and tracking performance between the proposed distributed algorithm and the corresponding CADPD algorithm is negligible through simulation evaluations.
文摘The two-station positioning system based on time difference and azimuth measurement has measurement redundancy. Therefore, not only can a positioning solution which is completely independent of the baseline length between two stations be derived, but also the baseline length can be solved as an unknown quantity. These findings not only enhance the performance of the two-station positioning system, but also provide a design basis for the construction of a self-organizing dynamic intelligent positioning system.