Several promising plasma biomarker proteins,such as amyloid-β(Aβ),tau,neurofilament light chain,and glial fibrillary acidic protein,are widely used for the diagnosis of neurodegenerative diseases.However,little is k...Several promising plasma biomarker proteins,such as amyloid-β(Aβ),tau,neurofilament light chain,and glial fibrillary acidic protein,are widely used for the diagnosis of neurodegenerative diseases.However,little is known about the long-term stability of these biomarker proteins in plasma samples stored at-80°C.We aimed to explore how storage time would affect the diagnostic accuracy of these biomarkers using a large cohort.Plasma samples from 229 cognitively unimpaired individuals,encompassing healthy controls and those experiencing subjective cognitive decline,as well as 99 patients with cognitive impairment,comprising those with mild cognitive impairment and dementia,were acquired from the Sino Longitudinal Study on Cognitive Decline project.These samples were stored at-80°C for up to 6 years before being used in this study.Our results showed that plasma levels of Aβ42,Aβ40,neurofilament light chain,and glial fibrillary acidic protein were not significantly correlated with sample storage time.However,the level of total tau showed a negative correlation with sample storage time.Notably,in individuals without cognitive impairment,plasma levels of total protein and tau phosphorylated protein threonine 181(p-tau181)also showed a negative correlation with sample storage time.This was not observed in individuals with cognitive impairment.Consequently,we speculate that the diagnostic accuracy of plasma p-tau181 and the p-tau181 to total tau ratio may be influenced by sample storage time.Therefore,caution is advised when using these plasma biomarkers for the identification of neurodegenerative diseases,such as Alzheimer's disease.Furthermore,in cohort studies,it is important to consider the impact of storage time on the overall results.展开更多
In this study,the nano-TiC/AZ61 composites with different heterogeneous bimodal grain(HBG)structures and uniform structure are obtained by regulating the extrusion speed.The effect of HBG structure on the mechanical p...In this study,the nano-TiC/AZ61 composites with different heterogeneous bimodal grain(HBG)structures and uniform structure are obtained by regulating the extrusion speed.The effect of HBG structure on the mechanical properties of the composites is investigated.The increasing ductility and toughening mechanism of HBG magnesium matrix composites are carefully discussed.When the extrusion speed increases from 0.75 mm/s to 2.5 mm/s or 3.5 mm/s,the microstructure transforms from uniform to HBG structure.Compared with Uniform-0.75 mm/s composite,Heterogeneous-3.5 mm/s composite achieves a 116.7%increase in ductility in the plastic deformation stage and almost no reduction in ultimate tensile strength.This is mainly because the lower plastic deformation inhomogeneity and higher strain hardening due to hetero-deformation induced(HDI)hardening.Moreover,Heterogeneous-3.5 mm/s composite achieves a 108.3%increase in toughness compared with the Uniform-0.75 mm/s composite.It is mainly because coarse grain(CG)bands can capture and blunt cracks,thereby increasing the energy dissipation for crack propagation and improving toughness.In addition,the CG band of the Heterogeneous-3.5 mm/s composite with larger grain size and lower dislocation density is more conducive to obtaining higher strain hardening and superior blunting crack capability.Thus,the increased ductility and toughness of the Heterogeneous-3.5 mm/s composite is more significant than that Heterogeneous-2.5 mm/s composite.展开更多
This paper takes college students as research subjects to investigate the factors affecting L2 Reading ability and their regulation strategies through scale surveys.The findings are as follows:(1)Linguistic factors ha...This paper takes college students as research subjects to investigate the factors affecting L2 Reading ability and their regulation strategies through scale surveys.The findings are as follows:(1)Linguistic factors have significant impacts on L2 Reading ability,and the influence of non-linguistic factors,such as non-intellectual factors and cultural background knowledge,is also important;and(2)flexible use of reading regulation strategies according to the learning conditions(such as the information extraction strategy,the metacognitive reading regulation strategy,and the interactive reading strategy)can effectively improve learners’L2 Reading ability.The findings of this study have important theoretical and practical value for improving L2 learners’Reading ability.展开更多
The existing research results show that a fixed single station must conduct three consecutive frequency shift measurements and obtain the target’s moving speed by constructing two frequency difference equations. This...The existing research results show that a fixed single station must conduct three consecutive frequency shift measurements and obtain the target’s moving speed by constructing two frequency difference equations. This article proposes a new method that requires only two consecutive measurements. While using the azimuth measurement to obtain the angular difference between two radial distances, it also conducts two consecutive Doppler frequency shift measurements at the same target azimuth. On the basis of this measurement, a frequency difference equation is first constructed and solved jointly with the Doppler frequency shift equation. By eliminating the velocity variable and using the measured angular difference to obtain the target’s lead angle, the target’s velocity can be solved by using the Doppler frequency shift equation again. The new method avoids the condition that the target must move equidistantly, which not only provides an achievable method for engineering applications but also lays a good foundation for further exploring the use of steady-state signals to achieve passive positioning.展开更多
Objective:To analyze the effect of perioperative comfort care for patients with hysteromyomectomy(HYS).Methods:Seventy cases of HYS patients admitted to our hospital from October 2022 to October 2023 were randomly sel...Objective:To analyze the effect of perioperative comfort care for patients with hysteromyomectomy(HYS).Methods:Seventy cases of HYS patients admitted to our hospital from October 2022 to October 2023 were randomly selected and divided into Group A(control group,35 cases,conventional care)and Group B(observation group 35 cases,comfort care).The effects of the two groups before and after nursing care were compared.Results:The self-rating anxiety(SAS)scores,exercise of self-care agency(ESCA)scores,and nursing satisfaction scores at the time of discharge of Group B were better than in Group A after nursing care(P<0.05).Conclusion:Perioperative comfort care for HYS patients improved the patient’s adverse emotions,self-care ability,and nursing satisfaction.展开更多
The mass loss and nose blunting of a projectile during high-speed deep penetration into concrete target may cause structural destruction and ballistic trajectory instability of the penetrator,obviously reducing the pe...The mass loss and nose blunting of a projectile during high-speed deep penetration into concrete target may cause structural destruction and ballistic trajectory instability of the penetrator,obviously reducing the penetration efficiency of penetrator.Provided that the work of friction between projectile and target is totally transformed into the heat to melt penetrator material at its nose surface,an engineering model is established for the mass loss and nose-blunting of the ogive-nosed projectile.A dimensionless formula for the relative mass loss of projectile is obtained by introducing the dimensionless impact function I and geometry function N of the projectile.The critical value V c0of the initial striking velocity is formulated,and the mass loss of projectile tends to increase weakly nonlinearly with I/N when V0〉V c0,whilst the mass loss is proportional to the initial kinetic energy of projectile when V0展开更多
The initial oblique and attacking angles as well as the asymmetrical nose abrasion may lead to bending or even fracture of a projectile,and the penetration efficiency decreases distinctly.The structural stability of a...The initial oblique and attacking angles as well as the asymmetrical nose abrasion may lead to bending or even fracture of a projectile,and the penetration efficiency decreases distinctly.The structural stability of a high-speed projectile non-normally penetrating into concrete and the parametric influences involved are analyzed with the mass abrasion taken into account.By considering the symmetrical or asymmetrical nose abrasion as well as the initial oblique and attacking angles,both the axial and the transverse drag forces acting on the projectile are derived.Based on the ideal elastic-plastic yield criterion,an approach is proposed for predicting the limit striking velocity(LSV)that is the highest velocity at which no yielding failure has occurred and the projectile can still maintain its integral structural stability.Furthermore,some particular penetration scenarios are separately discussed in detail.Based on the engineering model for the mass loss and nose-blunting of ogive-nose projectiles established in Part I of this study,the above approach is validated by several high-speed penetration tests.The analysis on parametric influences indicates that the LSV is reduced with an increase in the asymmetrical nose abrasion,thelength-diameter-ratio,and the concrete strength,as well as the oblique and attacking angles.Also,the LSV raises with an increase in the initial caliber-radius-head(CRH)and the dimensionless cartridge thickness of a projectile.展开更多
With the progress of the railway technology, the railway transportation is becoming more efficient, intelligent and faster. High speed trains, as a major part of the railway transportation, are engaged with passenger&...With the progress of the railway technology, the railway transportation is becoming more efficient, intelligent and faster. High speed trains, as a major part of the railway transportation, are engaged with passenger's safety, and therefore the reliability issue is very important in such vital systems. In this paper, a dependable speed controller core based on FPGA has been developed for high speed trains. To improve the reliability and mitigate single upset faults on basic speed controller, this paper proposes a new effective method which is based on hardware redundancy. In the proposed Hybrid Dual Duplex Redundancy(HDDR) method, the original controller is quadruplicated and correct values are voted through the comparator and error detection unit. We have analyzed the proposed system with Reliability, Availability, Mean time to failure and Security(RAMS) theory in order to evaluate the effectiveness of proposed scheme. Theoretical analysis shows that the Mean Time To Failure(MTTF) of the proposed system is 2.5 times better than the traditional Triple Modular Redundancy(TMR). Furthermore, the fault injection experimental results reveal that the capability of tolerating Single Event Upsets(SEUs) in the proposed method increases up to 7.5 times with respect to a regular speed controller.展开更多
Comparing and analyzing the difference between automatic-observed and manual-observed wind speed based on the wind speed parallel observations in two methods, we find that many elements can influence the difference be...Comparing and analyzing the difference between automatic-observed and manual-observed wind speed based on the wind speed parallel observations in two methods, we find that many elements can influence the difference between automatic-observed and manual-observed wind speed, including the levels of speed wind, observation instruments and different regions. According to these elements, correction has been conducted, and find that the correction according to the level of wind speed has the best correction effect.展开更多
Yihui1577 was bred after over 10 generations by crossing R16 and Yunan purple rice. Many new hybrid rice varieties have been bred with Yihui1577, of which Gangyou1577. Ilyou1577, Nyou1577 and Yixiang1577 were certifie...Yihui1577 was bred after over 10 generations by crossing R16 and Yunan purple rice. Many new hybrid rice varieties have been bred with Yihui1577, of which Gangyou1577. Ilyou1577, Nyou1577 and Yixiang1577 were certified by Sichuan Crop Variety Release Committee, Gangyou1577 and Yixiang1577 were certified by National Crop Variety Release Committee. The series varieties bred with Yihui1577 have been used widely with accumulated area of 1,200,000 ha. By using Yihui1577 as breeding material, an excellent restore line Yihui3003 and some other restore lines, such as Yihui1979 and Yihui315 with good quality and combination ability have been bred. Analysis of combination ability and stability of restore line Yihui1577 was made by using agricultural experimentation and statistical approach. The combination ability analysis was made by not complete dual crossing method with 4 CMS lines and 6 restorer lines. It shows that the general combination ability effect value of Yihui1577 is 0.226, while Minghui63 is -0.113. So the general combination ability of Yihui1577 is prior to that of Minghui63. Stability analysis shows that the F value of Gangyou1577 is 1.81378, while Sanyou63 is 1.40327, both doesn't reach significant level. So Gangyou1577 has the same stability as Sanyou63.The same conclusion is got in the stability analysis of the breeds of II you 1577, Yixiang1577, Nyou 1577 and so on.展开更多
Microstructure,texture,and mechanical properties of the extruded Mg-2.49Nd-1.82Gd-0.2Zn-0.2Zr alloy were investigated at different extrusion temperatures(260 and 320℃),extrusion ratios(10:1,15:1,and 30:1),and extrusi...Microstructure,texture,and mechanical properties of the extruded Mg-2.49Nd-1.82Gd-0.2Zn-0.2Zr alloy were investigated at different extrusion temperatures(260 and 320℃),extrusion ratios(10:1,15:1,and 30:1),and extrusion speeds(3 and 6 mm/s).The experimental results exhibited that the grain sizes after extrusion were much finer than that of the homogenized alloy,and the second phase showed streamline distribution along the extrusion direction(ED).With extrusion temperature increased from 260 to 320℃,the microstructure,texture,and mechanical properties of alloys changed slightly.The dynamic recrystallization(DRX)degree and grain sizes enhanced as the extrusion ratio increased from 10:1 to 30:1,and the strength gradually decreased but elongation(EL)increased.With the extrusion speed increased from 3 to 6 mm/s,the grain sizes and DRX degree increased significantly,and the samples presented the typical<2111>-<1123>rare-earth(RE)textures.The alloy extruded at 260℃ with extrusion ratio of 10:1 and extrusion speed of 3 mm/s showed the tensile yield strength(TYS)of 213 MPa and EL of 30.6%.After quantitatively analyzing the contribution of strengthening mechanisms,it was found that the grain boundary strengthening and dislocation strengthening played major roles among strengthening contributions.These results provide some guidelines for enlarging the industrial application of extruded Mg-RE alloy.展开更多
Autonomous learning is one of the objectives of multi-media college English teaching. On basis of the test of students' autonomous learning ability and the analysis of the results, this paper attempts to explore the ...Autonomous learning is one of the objectives of multi-media college English teaching. On basis of the test of students' autonomous learning ability and the analysis of the results, this paper attempts to explore the feasibility of fostering the autonomous learning ability in college English teaching.展开更多
[Objective] This study was to investigate the restoring ability of normal indica red rice Ruby and to carry out its restoring gene mapping. [Method] Normal indica red rice Ruby was hybridized with the sterile lines Zh...[Objective] This study was to investigate the restoring ability of normal indica red rice Ruby and to carry out its restoring gene mapping. [Method] Normal indica red rice Ruby was hybridized with the sterile lines Zhenxian 97A, D62A, G46A and D702A to prepare their F1, BC1 and F2 progenies, and the pollen fertilities of these progenies were investigated. Meanwhile the restoring genes were mapped using SSLP. [ Result] For the sterile lines tested, Ruby has a gene to restore their fertilities. This gene is located on the chromosome 7 and shows a genetic distance of 7.4 cM with RM182. Unlike the clustering distribution of the restoring genes on chromosome 10, it is a specific restoring gene. [ Conclusion] it is feasible to breed restoring genes controlling red color characters via transgene and backcross.展开更多
Through the research into college students' English autonomous learning ability of the non-English major students. That the cause why university students' English autonomous learning ability is weak is proved to be ...Through the research into college students' English autonomous learning ability of the non-English major students. That the cause why university students' English autonomous learning ability is weak is proved to be that they do not value the use of learning strategies. The use of learning strategies can promote the formation and enhancement of autonomous learning ability of the learners. Metacognitive strategy is a high-level management skill which can enable the learners to plan, regulate, monitor and evaluate actively their own learning process. Massive researches have proved whether metacognitive strategy is used successfully or not can directly affect the student learning result. So, it is necessary for teachers to cultivate and train the students to use metacogitive strategy in the university English teaching.展开更多
To select or develop an appropriate actuator is one of the key and difficult issues in the study of semi-active controlled landing gear. Performance of the actuator may directly affect the effectiveness of semi-active...To select or develop an appropriate actuator is one of the key and difficult issues in the study of semi-active controlled landing gear. Performance of the actuator may directly affect the effectiveness of semi-active control. In this article, parallel high-speed solenoid valves are chosen to be the actuators for the semi-active controlled landing gear and being studied. A nonlinear high-speed solenoid valve model is developed with the consideration of magnetic saturation characteristics and verified by test. According to the design rule of keeping the peak load as small as possible while absorbing the specified shock energy, a fuzzy PD control rule is designed. By the rule controller parameters can be self-regulated. The simulation results indicate that the semi-active control based on high-speed solenoid valve can effectively improve the control performance and reduce impact load during landing.展开更多
English is becoming more and more important in communicating as the further development of the reform and opening up. We English teacher should try our best to create and arrange a kind of language environment accordi...English is becoming more and more important in communicating as the further development of the reform and opening up. We English teacher should try our best to create and arrange a kind of language environment according to our students' practical life in order to improve and enhance their interest in English studying, to encourage them to practice English during their daily life and to cultivate their ability to communicate in English.展开更多
Objective:The institutionalization of care for patients with dementia is becoming a trend.Understanding the burden on employed caregivers and exploring associated factors are of great importance in practice.Therefore,...Objective:The institutionalization of care for patients with dementia is becoming a trend.Understanding the burden on employed caregivers and exploring associated factors are of great importance in practice.Therefore,this study aimed to examine the relationship between basic attributes,caring ability,and caregiver burden in employed caregivers practicing in nursing homes.Methods:This cross-sectional study included 541 employed caregivers in 11 four-star nursing homes in Zhejiang Province from April to December 2022.Caregiver burden was assessed using the Zarit Burden Interview(ZBI).Demographic characteristics of participants,characteristics of the older patients with dementia,caring characteristics,training in dementia care,and caring abilities were collected for analysis of influencing factors.A hierarchical multiple regression analysis was conducted to explore the factors influencing the burden on employed caregivers in nursing homes.Results:The ZBI score of employed caregivers in nursing homes was 40.42±10.18,representing a moderate caregiver burden.Factors such as age(U=27.82,P<0.001),residence(U=7.89,P<0.001),educational level(H=55.81,P<0.001),self-care of older patients with dementia(H=85.21,P<0.001),daily care hours(H=73.25,P<0.001),number of older people with dementia cared for(H=14.56,P<0.012)and training in dementia care(U=-9.43,P<0.001)were significantly associated with caregiver burden.Caring ability was negatively associated with caregiver burden(r=-0.22,P<0.01).Furthermore,after controlling for demographic characteristics,the characteristics of older people with dementia,caring characteristics,training in dementia care,and caring ability explained 8.5%,5.8%,and 4.8%of the caregiver burden,respectively.Conclusion:The burden of employed caregivers on patients with dementia in nursing homes can be attributed to various factors.We recommend tailored interventions,such as dementia care training and reviewing the number and duration of hours worked to reduce the burden experienced by caregivers.展开更多
Numerical weather prediction(NWP)models have always presented large forecasting errors of surface wind speeds over regions with complex terrain.In this study,surface wind forecasts from an operational NWP model,the SM...Numerical weather prediction(NWP)models have always presented large forecasting errors of surface wind speeds over regions with complex terrain.In this study,surface wind forecasts from an operational NWP model,the SMS-WARR(Shanghai Meteorological Service-WRF ADAS Rapid Refresh System),are analyzed to quantitatively reveal the relationships between the forecasted surface wind speed errors and terrain features,with the intent of providing clues to better apply the NWP model to complex terrain regions.The terrain features are described by three parameters:the standard deviation of the model grid-scale orography,terrain height error of the model,and slope angle.The results show that the forecast bias has a unimodal distribution with a change in the standard deviation of orography.The minimum ME(the mean value of bias)is 1.2 m s^(-1) when the standard deviation is between 60 and 70 m.A positive correlation exists between bias and terrain height error,with the ME increasing by 10%−30%for every 200 m increase in terrain height error.The ME decreases by 65.6%when slope angle increases from(0.5°−1.5°)to larger than 3.5°for uphill winds but increases by 35.4%when the absolute value of slope angle increases from(0.5°−1.5°)to(2.5°−3.5°)for downhill winds.Several sensitivity experiments are carried out with a model output statistical(MOS)calibration model for surface wind speeds and ME(RMSE)has been reduced by 90%(30%)by introducing terrain parameters,demonstrating the value of this study.展开更多
The research aims to improve the performance of image recognition methods based on a description in the form of a set of keypoint descriptors.The main focus is on increasing the speed of establishing the relevance of ...The research aims to improve the performance of image recognition methods based on a description in the form of a set of keypoint descriptors.The main focus is on increasing the speed of establishing the relevance of object and etalon descriptions while maintaining the required level of classification efficiency.The class to be recognized is represented by an infinite set of images obtained from the etalon by applying arbitrary geometric transformations.It is proposed to reduce the descriptions for the etalon database by selecting the most significant descriptor components according to the information content criterion.The informativeness of an etalon descriptor is estimated by the difference of the closest distances to its own and other descriptions.The developed method determines the relevance of the full description of the recognized object with the reduced description of the etalons.Several practical models of the classifier with different options for establishing the correspondence between object descriptors and etalons are considered.The results of the experimental modeling of the proposed methods for a database including images of museum jewelry are presented.The test sample is formed as a set of images from the etalon database and out of the database with the application of geometric transformations of scale and rotation in the field of view.The practical problems of determining the threshold for the number of votes,based on which a classification decision is made,have been researched.Modeling has revealed the practical possibility of tenfold reducing descriptions with full preservation of classification accuracy.Reducing the descriptions by twenty times in the experiment leads to slightly decreased accuracy.The speed of the analysis increases in proportion to the degree of reduction.The use of reduction by the informativeness criterion confirmed the possibility of obtaining the most significant subset of features for classification,which guarantees a decent level of accuracy.展开更多
The maintenance of sand-fixing vegetation is important for the stability of artificial sand-fixing systems in which seed dispersal plays a key role.Based on field wind tunnel experiments using 11 common plant species ...The maintenance of sand-fixing vegetation is important for the stability of artificial sand-fixing systems in which seed dispersal plays a key role.Based on field wind tunnel experiments using 11 common plant species on the southeastern edge of the Tengger Desert,China,we studied the secondary seed dispersal in the fixed and semi-fixed sand dunes as well as in the mobile dunes in order to understand the limitations of vegetation regeneration and the maintenance of its stability.Our results indicated that there were significant variations among the selected 11 plant species in the threshold of wind speed(TWS).The TWS of Caragana korshinskii was the highest among the 11 plant species,whereas that of Echinops gmelinii was the lowest.Seed morphological traits and underlying surface could generally explain the TWS.During the secondary seed dispersal processes,the proportions of seeds that did not disperse(no dispersal)and only dispersed over short distance(short-distance dispersal within the wind tunnel test section)were significantly higher than those of seeds that were buried(including lost seeds)and dispersed over long distance(long-distance dispersal beyond the wind tunnel test section).Compared with other habitats,the mobile dunes were the most difficult places for secondary seed dispersal.Buried seeds were the easiest to be found in the semi-fixed sand dunes,whereas fixed sand dunes were the best sites for seeds that dispersed over long distance.The results of linear mixed models showed that after controlling the dispersal distance,smaller and rounder seeds dispersed farther.Shape index and wind speed were the two significant influencing factors on the burial of seeds.The explanatory power of wind speed,underlying surface,and seed morphological traits on the seeds that did not disperse and dispersed over short distance was far greater than that on the seeds that were buried and dispersed over long distance,implying that the processes and mechanisms of burial and long-distance dispersal are more complex.In summary,most seeds in the study area either did not move,were buried,or dispersed over short distance,promoting local vegetation regeneration.展开更多
基金supported by the National Key Research&Development Program of China,Nos.2021YFC2501205(to YC),2022YFC24069004(to JL)the STI2030-Major Project,Nos.2021ZD0201101(to YC),2022ZD0211800(to YH)+2 种基金the National Natural Science Foundation of China(Major International Joint Research Project),No.82020108013(to YH)the Sino-German Center for Research Promotion,No.M-0759(to YH)a grant from Beijing Municipal Science&Technology Commission(Beijing Brain Initiative),No.Z201100005520018(to JL)。
文摘Several promising plasma biomarker proteins,such as amyloid-β(Aβ),tau,neurofilament light chain,and glial fibrillary acidic protein,are widely used for the diagnosis of neurodegenerative diseases.However,little is known about the long-term stability of these biomarker proteins in plasma samples stored at-80°C.We aimed to explore how storage time would affect the diagnostic accuracy of these biomarkers using a large cohort.Plasma samples from 229 cognitively unimpaired individuals,encompassing healthy controls and those experiencing subjective cognitive decline,as well as 99 patients with cognitive impairment,comprising those with mild cognitive impairment and dementia,were acquired from the Sino Longitudinal Study on Cognitive Decline project.These samples were stored at-80°C for up to 6 years before being used in this study.Our results showed that plasma levels of Aβ42,Aβ40,neurofilament light chain,and glial fibrillary acidic protein were not significantly correlated with sample storage time.However,the level of total tau showed a negative correlation with sample storage time.Notably,in individuals without cognitive impairment,plasma levels of total protein and tau phosphorylated protein threonine 181(p-tau181)also showed a negative correlation with sample storage time.This was not observed in individuals with cognitive impairment.Consequently,we speculate that the diagnostic accuracy of plasma p-tau181 and the p-tau181 to total tau ratio may be influenced by sample storage time.Therefore,caution is advised when using these plasma biomarkers for the identification of neurodegenerative diseases,such as Alzheimer's disease.Furthermore,in cohort studies,it is important to consider the impact of storage time on the overall results.
基金support from China Scholarship Council(No.202107000038)the Na-tional Natural Science Foundation of China(52004227).
文摘In this study,the nano-TiC/AZ61 composites with different heterogeneous bimodal grain(HBG)structures and uniform structure are obtained by regulating the extrusion speed.The effect of HBG structure on the mechanical properties of the composites is investigated.The increasing ductility and toughening mechanism of HBG magnesium matrix composites are carefully discussed.When the extrusion speed increases from 0.75 mm/s to 2.5 mm/s or 3.5 mm/s,the microstructure transforms from uniform to HBG structure.Compared with Uniform-0.75 mm/s composite,Heterogeneous-3.5 mm/s composite achieves a 116.7%increase in ductility in the plastic deformation stage and almost no reduction in ultimate tensile strength.This is mainly because the lower plastic deformation inhomogeneity and higher strain hardening due to hetero-deformation induced(HDI)hardening.Moreover,Heterogeneous-3.5 mm/s composite achieves a 108.3%increase in toughness compared with the Uniform-0.75 mm/s composite.It is mainly because coarse grain(CG)bands can capture and blunt cracks,thereby increasing the energy dissipation for crack propagation and improving toughness.In addition,the CG band of the Heterogeneous-3.5 mm/s composite with larger grain size and lower dislocation density is more conducive to obtaining higher strain hardening and superior blunting crack capability.Thus,the increased ductility and toughness of the Heterogeneous-3.5 mm/s composite is more significant than that Heterogeneous-2.5 mm/s composite.
基金funded by the Social Sciences Annual Research Project of Shanghai“A Study on the Interactive Processing Mechanism of English L2 Text Reading”(Grant No.2021BYY008).
文摘This paper takes college students as research subjects to investigate the factors affecting L2 Reading ability and their regulation strategies through scale surveys.The findings are as follows:(1)Linguistic factors have significant impacts on L2 Reading ability,and the influence of non-linguistic factors,such as non-intellectual factors and cultural background knowledge,is also important;and(2)flexible use of reading regulation strategies according to the learning conditions(such as the information extraction strategy,the metacognitive reading regulation strategy,and the interactive reading strategy)can effectively improve learners’L2 Reading ability.The findings of this study have important theoretical and practical value for improving L2 learners’Reading ability.
文摘The existing research results show that a fixed single station must conduct three consecutive frequency shift measurements and obtain the target’s moving speed by constructing two frequency difference equations. This article proposes a new method that requires only two consecutive measurements. While using the azimuth measurement to obtain the angular difference between two radial distances, it also conducts two consecutive Doppler frequency shift measurements at the same target azimuth. On the basis of this measurement, a frequency difference equation is first constructed and solved jointly with the Doppler frequency shift equation. By eliminating the velocity variable and using the measured angular difference to obtain the target’s lead angle, the target’s velocity can be solved by using the Doppler frequency shift equation again. The new method avoids the condition that the target must move equidistantly, which not only provides an achievable method for engineering applications but also lays a good foundation for further exploring the use of steady-state signals to achieve passive positioning.
基金Research project of Sichuan Maternal and Child Health Association(No.:22FXYB12)Research project of Sichuan Health and Family Planning Commission(No.:16PJ399)。
文摘Objective:To analyze the effect of perioperative comfort care for patients with hysteromyomectomy(HYS).Methods:Seventy cases of HYS patients admitted to our hospital from October 2022 to October 2023 were randomly selected and divided into Group A(control group,35 cases,conventional care)and Group B(observation group 35 cases,comfort care).The effects of the two groups before and after nursing care were compared.Results:The self-rating anxiety(SAS)scores,exercise of self-care agency(ESCA)scores,and nursing satisfaction scores at the time of discharge of Group B were better than in Group A after nursing care(P<0.05).Conclusion:Perioperative comfort care for HYS patients improved the patient’s adverse emotions,self-care ability,and nursing satisfaction.
基金supported by the National Outstanding Young Scientists Foundation of China(11225213)the Funds for Creative Research Groups of China(51321064)the National Natural Science Foundation of China(11172282 and 51378015)
文摘The mass loss and nose blunting of a projectile during high-speed deep penetration into concrete target may cause structural destruction and ballistic trajectory instability of the penetrator,obviously reducing the penetration efficiency of penetrator.Provided that the work of friction between projectile and target is totally transformed into the heat to melt penetrator material at its nose surface,an engineering model is established for the mass loss and nose-blunting of the ogive-nosed projectile.A dimensionless formula for the relative mass loss of projectile is obtained by introducing the dimensionless impact function I and geometry function N of the projectile.The critical value V c0of the initial striking velocity is formulated,and the mass loss of projectile tends to increase weakly nonlinearly with I/N when V0〉V c0,whilst the mass loss is proportional to the initial kinetic energy of projectile when V0
基金supported by the National Outstanding Young Scientists Foundation of China(11225213)the Funds for Creative Research Groups of China(51321064)the National Natural Science Foundation of China(11172282 and 51378015)
文摘The initial oblique and attacking angles as well as the asymmetrical nose abrasion may lead to bending or even fracture of a projectile,and the penetration efficiency decreases distinctly.The structural stability of a high-speed projectile non-normally penetrating into concrete and the parametric influences involved are analyzed with the mass abrasion taken into account.By considering the symmetrical or asymmetrical nose abrasion as well as the initial oblique and attacking angles,both the axial and the transverse drag forces acting on the projectile are derived.Based on the ideal elastic-plastic yield criterion,an approach is proposed for predicting the limit striking velocity(LSV)that is the highest velocity at which no yielding failure has occurred and the projectile can still maintain its integral structural stability.Furthermore,some particular penetration scenarios are separately discussed in detail.Based on the engineering model for the mass loss and nose-blunting of ogive-nose projectiles established in Part I of this study,the above approach is validated by several high-speed penetration tests.The analysis on parametric influences indicates that the LSV is reduced with an increase in the asymmetrical nose abrasion,thelength-diameter-ratio,and the concrete strength,as well as the oblique and attacking angles.Also,the LSV raises with an increase in the initial caliber-radius-head(CRH)and the dimensionless cartridge thickness of a projectile.
文摘With the progress of the railway technology, the railway transportation is becoming more efficient, intelligent and faster. High speed trains, as a major part of the railway transportation, are engaged with passenger's safety, and therefore the reliability issue is very important in such vital systems. In this paper, a dependable speed controller core based on FPGA has been developed for high speed trains. To improve the reliability and mitigate single upset faults on basic speed controller, this paper proposes a new effective method which is based on hardware redundancy. In the proposed Hybrid Dual Duplex Redundancy(HDDR) method, the original controller is quadruplicated and correct values are voted through the comparator and error detection unit. We have analyzed the proposed system with Reliability, Availability, Mean time to failure and Security(RAMS) theory in order to evaluate the effectiveness of proposed scheme. Theoretical analysis shows that the Mean Time To Failure(MTTF) of the proposed system is 2.5 times better than the traditional Triple Modular Redundancy(TMR). Furthermore, the fault injection experimental results reveal that the capability of tolerating Single Event Upsets(SEUs) in the proposed method increases up to 7.5 times with respect to a regular speed controller.
基金Supported by Meteorological Data Sharing Center Project (2005DKA31700-01,GX07-01-01)2009 Specific Research in Non-profit Sector (200906041-053)
文摘Comparing and analyzing the difference between automatic-observed and manual-observed wind speed based on the wind speed parallel observations in two methods, we find that many elements can influence the difference between automatic-observed and manual-observed wind speed, including the levels of speed wind, observation instruments and different regions. According to these elements, correction has been conducted, and find that the correction according to the level of wind speed has the best correction effect.
基金The study is approved by the state 863 program in China (the program No.2002AA2070002)and Sichuan province 15 rice breeding key project.
文摘Yihui1577 was bred after over 10 generations by crossing R16 and Yunan purple rice. Many new hybrid rice varieties have been bred with Yihui1577, of which Gangyou1577. Ilyou1577, Nyou1577 and Yixiang1577 were certified by Sichuan Crop Variety Release Committee, Gangyou1577 and Yixiang1577 were certified by National Crop Variety Release Committee. The series varieties bred with Yihui1577 have been used widely with accumulated area of 1,200,000 ha. By using Yihui1577 as breeding material, an excellent restore line Yihui3003 and some other restore lines, such as Yihui1979 and Yihui315 with good quality and combination ability have been bred. Analysis of combination ability and stability of restore line Yihui1577 was made by using agricultural experimentation and statistical approach. The combination ability analysis was made by not complete dual crossing method with 4 CMS lines and 6 restorer lines. It shows that the general combination ability effect value of Yihui1577 is 0.226, while Minghui63 is -0.113. So the general combination ability of Yihui1577 is prior to that of Minghui63. Stability analysis shows that the F value of Gangyou1577 is 1.81378, while Sanyou63 is 1.40327, both doesn't reach significant level. So Gangyou1577 has the same stability as Sanyou63.The same conclusion is got in the stability analysis of the breeds of II you 1577, Yixiang1577, Nyou 1577 and so on.
基金supported by the National Science and Technology Major Project,China(No.2019-VI-0004-0118)the National Natural Science Foundation of China(No.51771152)the National Key R&D Program of China(No.2018YFB1106800)。
文摘Microstructure,texture,and mechanical properties of the extruded Mg-2.49Nd-1.82Gd-0.2Zn-0.2Zr alloy were investigated at different extrusion temperatures(260 and 320℃),extrusion ratios(10:1,15:1,and 30:1),and extrusion speeds(3 and 6 mm/s).The experimental results exhibited that the grain sizes after extrusion were much finer than that of the homogenized alloy,and the second phase showed streamline distribution along the extrusion direction(ED).With extrusion temperature increased from 260 to 320℃,the microstructure,texture,and mechanical properties of alloys changed slightly.The dynamic recrystallization(DRX)degree and grain sizes enhanced as the extrusion ratio increased from 10:1 to 30:1,and the strength gradually decreased but elongation(EL)increased.With the extrusion speed increased from 3 to 6 mm/s,the grain sizes and DRX degree increased significantly,and the samples presented the typical<2111>-<1123>rare-earth(RE)textures.The alloy extruded at 260℃ with extrusion ratio of 10:1 and extrusion speed of 3 mm/s showed the tensile yield strength(TYS)of 213 MPa and EL of 30.6%.After quantitatively analyzing the contribution of strengthening mechanisms,it was found that the grain boundary strengthening and dislocation strengthening played major roles among strengthening contributions.These results provide some guidelines for enlarging the industrial application of extruded Mg-RE alloy.
文摘Autonomous learning is one of the objectives of multi-media college English teaching. On basis of the test of students' autonomous learning ability and the analysis of the results, this paper attempts to explore the feasibility of fostering the autonomous learning ability in college English teaching.
基金Supported by Sci-tech Program for Excellent Young Scientists of Sichuan Province(01ZQ052)~~
文摘[Objective] This study was to investigate the restoring ability of normal indica red rice Ruby and to carry out its restoring gene mapping. [Method] Normal indica red rice Ruby was hybridized with the sterile lines Zhenxian 97A, D62A, G46A and D702A to prepare their F1, BC1 and F2 progenies, and the pollen fertilities of these progenies were investigated. Meanwhile the restoring genes were mapped using SSLP. [ Result] For the sterile lines tested, Ruby has a gene to restore their fertilities. This gene is located on the chromosome 7 and shows a genetic distance of 7.4 cM with RM182. Unlike the clustering distribution of the restoring genes on chromosome 10, it is a specific restoring gene. [ Conclusion] it is feasible to breed restoring genes controlling red color characters via transgene and backcross.
文摘Through the research into college students' English autonomous learning ability of the non-English major students. That the cause why university students' English autonomous learning ability is weak is proved to be that they do not value the use of learning strategies. The use of learning strategies can promote the formation and enhancement of autonomous learning ability of the learners. Metacognitive strategy is a high-level management skill which can enable the learners to plan, regulate, monitor and evaluate actively their own learning process. Massive researches have proved whether metacognitive strategy is used successfully or not can directly affect the student learning result. So, it is necessary for teachers to cultivate and train the students to use metacogitive strategy in the university English teaching.
基金Aeronautical Science Foundation of China (04B52012, 98B52023)
文摘To select or develop an appropriate actuator is one of the key and difficult issues in the study of semi-active controlled landing gear. Performance of the actuator may directly affect the effectiveness of semi-active control. In this article, parallel high-speed solenoid valves are chosen to be the actuators for the semi-active controlled landing gear and being studied. A nonlinear high-speed solenoid valve model is developed with the consideration of magnetic saturation characteristics and verified by test. According to the design rule of keeping the peak load as small as possible while absorbing the specified shock energy, a fuzzy PD control rule is designed. By the rule controller parameters can be self-regulated. The simulation results indicate that the semi-active control based on high-speed solenoid valve can effectively improve the control performance and reduce impact load during landing.
文摘English is becoming more and more important in communicating as the further development of the reform and opening up. We English teacher should try our best to create and arrange a kind of language environment according to our students' practical life in order to improve and enhance their interest in English studying, to encourage them to practice English during their daily life and to cultivate their ability to communicate in English.
基金supported by the Department of Science and Technology of Zhejiang Province(LGF22H250002)the Health Commission of Zhejiang Province(2024KY002 to L.C.,2024KY617 to L.W.,2022KY004 to J.B.)The views expressed are those of the authors and not necessarily those of the funders.
文摘Objective:The institutionalization of care for patients with dementia is becoming a trend.Understanding the burden on employed caregivers and exploring associated factors are of great importance in practice.Therefore,this study aimed to examine the relationship between basic attributes,caring ability,and caregiver burden in employed caregivers practicing in nursing homes.Methods:This cross-sectional study included 541 employed caregivers in 11 four-star nursing homes in Zhejiang Province from April to December 2022.Caregiver burden was assessed using the Zarit Burden Interview(ZBI).Demographic characteristics of participants,characteristics of the older patients with dementia,caring characteristics,training in dementia care,and caring abilities were collected for analysis of influencing factors.A hierarchical multiple regression analysis was conducted to explore the factors influencing the burden on employed caregivers in nursing homes.Results:The ZBI score of employed caregivers in nursing homes was 40.42±10.18,representing a moderate caregiver burden.Factors such as age(U=27.82,P<0.001),residence(U=7.89,P<0.001),educational level(H=55.81,P<0.001),self-care of older patients with dementia(H=85.21,P<0.001),daily care hours(H=73.25,P<0.001),number of older people with dementia cared for(H=14.56,P<0.012)and training in dementia care(U=-9.43,P<0.001)were significantly associated with caregiver burden.Caring ability was negatively associated with caregiver burden(r=-0.22,P<0.01).Furthermore,after controlling for demographic characteristics,the characteristics of older people with dementia,caring characteristics,training in dementia care,and caring ability explained 8.5%,5.8%,and 4.8%of the caregiver burden,respectively.Conclusion:The burden of employed caregivers on patients with dementia in nursing homes can be attributed to various factors.We recommend tailored interventions,such as dementia care training and reviewing the number and duration of hours worked to reduce the burden experienced by caregivers.
基金supported by the National Natural Science Foundation of China(No.U2142206).
文摘Numerical weather prediction(NWP)models have always presented large forecasting errors of surface wind speeds over regions with complex terrain.In this study,surface wind forecasts from an operational NWP model,the SMS-WARR(Shanghai Meteorological Service-WRF ADAS Rapid Refresh System),are analyzed to quantitatively reveal the relationships between the forecasted surface wind speed errors and terrain features,with the intent of providing clues to better apply the NWP model to complex terrain regions.The terrain features are described by three parameters:the standard deviation of the model grid-scale orography,terrain height error of the model,and slope angle.The results show that the forecast bias has a unimodal distribution with a change in the standard deviation of orography.The minimum ME(the mean value of bias)is 1.2 m s^(-1) when the standard deviation is between 60 and 70 m.A positive correlation exists between bias and terrain height error,with the ME increasing by 10%−30%for every 200 m increase in terrain height error.The ME decreases by 65.6%when slope angle increases from(0.5°−1.5°)to larger than 3.5°for uphill winds but increases by 35.4%when the absolute value of slope angle increases from(0.5°−1.5°)to(2.5°−3.5°)for downhill winds.Several sensitivity experiments are carried out with a model output statistical(MOS)calibration model for surface wind speeds and ME(RMSE)has been reduced by 90%(30%)by introducing terrain parameters,demonstrating the value of this study.
基金This research was funded by Prince Sattam bin Abdulaziz University(Project Number PSAU/2023/01/25387).
文摘The research aims to improve the performance of image recognition methods based on a description in the form of a set of keypoint descriptors.The main focus is on increasing the speed of establishing the relevance of object and etalon descriptions while maintaining the required level of classification efficiency.The class to be recognized is represented by an infinite set of images obtained from the etalon by applying arbitrary geometric transformations.It is proposed to reduce the descriptions for the etalon database by selecting the most significant descriptor components according to the information content criterion.The informativeness of an etalon descriptor is estimated by the difference of the closest distances to its own and other descriptions.The developed method determines the relevance of the full description of the recognized object with the reduced description of the etalons.Several practical models of the classifier with different options for establishing the correspondence between object descriptors and etalons are considered.The results of the experimental modeling of the proposed methods for a database including images of museum jewelry are presented.The test sample is formed as a set of images from the etalon database and out of the database with the application of geometric transformations of scale and rotation in the field of view.The practical problems of determining the threshold for the number of votes,based on which a classification decision is made,have been researched.Modeling has revealed the practical possibility of tenfold reducing descriptions with full preservation of classification accuracy.Reducing the descriptions by twenty times in the experiment leads to slightly decreased accuracy.The speed of the analysis increases in proportion to the degree of reduction.The use of reduction by the informativeness criterion confirmed the possibility of obtaining the most significant subset of features for classification,which guarantees a decent level of accuracy.
基金supported by the Key R&D Program of Ningxia Hui Autonomous Region,China(2021BEG03008)the Natural Science Foundation of Ningxia Hui Autonomous Region,China(2021AAC03083).
文摘The maintenance of sand-fixing vegetation is important for the stability of artificial sand-fixing systems in which seed dispersal plays a key role.Based on field wind tunnel experiments using 11 common plant species on the southeastern edge of the Tengger Desert,China,we studied the secondary seed dispersal in the fixed and semi-fixed sand dunes as well as in the mobile dunes in order to understand the limitations of vegetation regeneration and the maintenance of its stability.Our results indicated that there were significant variations among the selected 11 plant species in the threshold of wind speed(TWS).The TWS of Caragana korshinskii was the highest among the 11 plant species,whereas that of Echinops gmelinii was the lowest.Seed morphological traits and underlying surface could generally explain the TWS.During the secondary seed dispersal processes,the proportions of seeds that did not disperse(no dispersal)and only dispersed over short distance(short-distance dispersal within the wind tunnel test section)were significantly higher than those of seeds that were buried(including lost seeds)and dispersed over long distance(long-distance dispersal beyond the wind tunnel test section).Compared with other habitats,the mobile dunes were the most difficult places for secondary seed dispersal.Buried seeds were the easiest to be found in the semi-fixed sand dunes,whereas fixed sand dunes were the best sites for seeds that dispersed over long distance.The results of linear mixed models showed that after controlling the dispersal distance,smaller and rounder seeds dispersed farther.Shape index and wind speed were the two significant influencing factors on the burial of seeds.The explanatory power of wind speed,underlying surface,and seed morphological traits on the seeds that did not disperse and dispersed over short distance was far greater than that on the seeds that were buried and dispersed over long distance,implying that the processes and mechanisms of burial and long-distance dispersal are more complex.In summary,most seeds in the study area either did not move,were buried,or dispersed over short distance,promoting local vegetation regeneration.