In reptiles,such as the red-eared slider turtle(Trachemys scripta elegans),gonadal sex determination is highly dependent on the environmental temperature during embryonic stages.This complex process,which leads to dif...In reptiles,such as the red-eared slider turtle(Trachemys scripta elegans),gonadal sex determination is highly dependent on the environmental temperature during embryonic stages.This complex process,which leads to differentiation into either testes or ovaries,is governed by the finely tuned expression of upstream genes,notably the testis-promoting gene Dmrt1 and the ovary-promoting gene Foxl2.Recent studies have identified epigenetic regulation as a crucial factor in testis development,with the H3K27me3 demethylase KDM6B being essential for Dmrt1 expression in T.s.elegans.However,whether KDM6B alone can induce testicular differentiation remains unclear.In this study,we found that overexpression of Kdm6b in T.s.elegans embryos induced the male development pathway,accompanied by a rapid increase in the gonadal expression of Dmrt1 at 31°C,a temperature typically resulting in female development.Notably,this sex reversal could be entirely rescued by Dmrt1 knockdown.These findings demonstrate that Kdm6b is sufficient for commitment to the male pathway,underscoring its role as a critical epigenetic regulator in the sex determination of the red-eared slider turtle.展开更多
The refugee determination system directly affects whether or not an asylum seeker can obtain a country’s legal protection. The rational construction of China’s refugee determination system is not only the need to co...The refugee determination system directly affects whether or not an asylum seeker can obtain a country’s legal protection. The rational construction of China’s refugee determination system is not only the need to comply with China’s obligations under the International Refugee Convention, but also the requirement for the protection of the legitimate rights of refugees in China. Under the current framework of international law and domestic law, we should gradually improve China’s legal system of refugee status determination, and we should determine refugee screening agencies and define their division of labor and powers rationally, according to the actual situation of China. In the meantime, we should attach importance to undertaking China’s international obligations and strengthening international cooperation in refugee relief.展开更多
As an important sensor in the navigation systems,star sensors and the gyro play important roles in spacecraft attitude determination system.Complex environmental factors are the main sources of error in attitude deter...As an important sensor in the navigation systems,star sensors and the gyro play important roles in spacecraft attitude determination system.Complex environmental factors are the main sources of error in attitude determination.The error influence of different benchmarks and the disintegration mode between the star sensor and the gyro is analyzed in theory.The integrated design of the star sensor and the gyro on the same benchmark can effectively avoid the error influence and improves the spacecraft attitude determination accuracy.Simulation results indicate that when the stars sensor optical axis vectors overlap the reference coordinate axis of the gyro in the same benchmark,the attitude determination accuracy improves.展开更多
In view of the problem that the current single-antenna GPS attitude determination system can only determine the body attitude when the sideslip angle is zero and the multiantenna GPS/SINS integrated navigation system ...In view of the problem that the current single-antenna GPS attitude determination system can only determine the body attitude when the sideslip angle is zero and the multiantenna GPS/SINS integrated navigation system is of large volume, high cost, and complex structure, this approach is presented to determine the attitude based on vector space with single-antenna GPS and accelerometers in the micro inertial measurement unit （MIMU）. It can provide real-time and accurate attitude information. Subsequently, the single-antenna GPS/SINS integrated navigation system is designed based on the combination of position, velocity, and attitude. Finally the semi- physical simulations of single-antenna GPS attitude determination system and single-antenna GPS/SINS integrated navigation system are carried out. The simulation results, based on measured data, show that the single-antenna GPS/SINS system can provide more accurate navigation information compared to the GPS/SINS system, based on the combination of position and velocity. Furthermore, the single-antenna GPS/SINS system is characteristic of lower cost and simpler structure. It provides the basis for the application of a single-antenna GPS/SINS integrated navigation system in a micro aerial vehicle （MAV）.展开更多
The Satellite Positioning and Orbit Determination System(SPODS)is a software package for GNSS positioning/orbit determination,developed by the Xi’an Research Institute of Surveying and Mapping.So far it has been able...The Satellite Positioning and Orbit Determination System(SPODS)is a software package for GNSS positioning/orbit determination,developed by the Xi’an Research Institute of Surveying and Mapping.So far it has been able to analyse GPS data and has the capability of high precision GPS positioning and orbit determination.The underlying theory and the performance evaluation are briefly addressed in this paper.The experiments are carried out with GPS data collected from about 127 IGS stations during 4~10 January 2009.The results show that the RMS 1D difference is 1.1 cm between SPODS orbits and final IGS combined orbits,and that the repeatability of daily solutions of station coordinates is 1.5 mm for horizontal components,and 4.5 mm for vertical component,and that the consistency of ERP solutions with IGS final products is 0.025 mas,0.093 mas and 0.013 ms/d respectively for pole coordinates and LOD.展开更多
This paper discusses the design and implementation of a low cost multi-sensor integrated attitude determination system for small unmanned aerial vehicles( UAVs),which uses strapdown inertial navigation system( SINS) b...This paper discusses the design and implementation of a low cost multi-sensor integrated attitude determination system for small unmanned aerial vehicles( UAVs),which uses strapdown inertial navigation system( SINS) based on micro electromechanical system( MEMS) inertial sensors,commercial GPS receiver,and 3-axis magnetometer.MEMS-SINS initial attitude determination cannot be well performed for the reason that the MEMS inertial sensors biases are time-varying and poor repeatability,therefore in this paper the magnetometer and inclinometer are used to assist the MEMS-SINS initial attitude determination and MEMS inertial sensors field calibration.Furthermore,the attitude determination algorithms are presented to estimate the full attitude during GPS signal outage and non-accelerating situation.Additionally,the attitude information estimation results are compared with the reference of the non-magnetic marble platform and 3-axis turntable.Then the attitude estimation precision satisfies the requirement of attitude measurement for small UAVs during GPS signal outage and availability.Finally,the small UAV autonomous flight test results show that the low cost and real-time attitude determination system can yield continuous,reliable and effective attitude information for small UAVs.展开更多
Although inductively coupled plasma mass spectrometry(ICP-MS) retains high sensitivity and has been intensively used for the measurement of ^(99)Tc, it usually suffers from tedious, expensive, and timeconsuming sample...Although inductively coupled plasma mass spectrometry(ICP-MS) retains high sensitivity and has been intensively used for the measurement of ^(99)Tc, it usually suffers from tedious, expensive, and timeconsuming sample pretreatments due to the isobaric interferences from ^(99)Ru and ^(98)Mo^(1)H. Herein, capillary electrophoresis(CE) was applied as sample introduction system for the sensitive, and interferencefree determination of ^(99)TcO_(4)^(-) from RuO_(4)^(-), and MoO_(4)^(2-) by ICP-MS with a simple sample treatment. Compared to the conventional methods, the hyphenated CE-ICP-MS avoids the use of expensive separation resins and reduces the consumption of mineral acid, representing a simpler, more efficient and environmentally benign approach. Moreover, the proposed method exhibits higher accuracy compared with the mathematical correction method using the natural isotope ratio of ^(99)Ru and ^(101)Ru, and significantly reduces sample consumption and the amount of waste, thus remarkably alleviating the radioactive exposure to operators and the pressure of radioactive waste treatment. Under the optimized conditions, the detection limits of 25 μg/L and 0.06 μg/L were obtained for RuO_(4)^(-) and ReO_(4)^(-)(Tc was replaced by Re), respectively, with relative standard deviation(RSD) lower than 5%. In addition, efficient recoveries of RuO_(4)^(-),ReO_(4)^(-),and ^(99)TcO_(4)^(-) from simulated Hanford site groundwater were achieved. The method is expected to be a promising candidate for sensitive and accurate analysis of ^(99)Tc from contaminated environmental samples.展开更多
The deteriorated continuous rigid frame bridge is strengthened by external prestressing. Static loading tests wereconducted before and after the bridge rehabilitation to verify the effectiveness of the rehabilitation ...The deteriorated continuous rigid frame bridge is strengthened by external prestressing. Static loading tests wereconducted before and after the bridge rehabilitation to verify the effectiveness of the rehabilitation process. Thestiffness of the repaired bridge is improved, and the maximum deflection of the load test is reduced from 37.9 to27.6 mm. A bridge health monitoring system is installed after the bridge is reinforced. To achieve an easy assessmentof the bridge’s safety status by directly using transferred data, a real-time safety warning system is createdbased on a five-level safety standard. The threshold for each safety level will be determined by theoretical calculationsand the outcomes of static loading tests. The highest risk threshold will be set at the ultimate limit statevalue. The remaining levels, namely middle risk, low risk, and very low risk, will be determined usingreduction coefficients of 0.95, 0.9, and 0.8, respectively.展开更多
The reaction rate constant is a crucial kinetic parameter that governs the charge and discharge performance of batteries,particularly in high-rate and thick-electrode applications.However,conventional estimation or fi...The reaction rate constant is a crucial kinetic parameter that governs the charge and discharge performance of batteries,particularly in high-rate and thick-electrode applications.However,conventional estimation or fitting methods often overestimate the charge transfer overpotential,leading to substantial errors in reaction rate constant measurements.These inaccuracies hinder the accurate prediction of voltage profiles and overall cell performance.In this study,we propose the characteristic time-decomposed overpotential(CTDO)method,which employs a single-layer particle electrode(SLPE)structure to eliminate interference overpotentials.By leveraging the distribution of relaxation times(DRT),our method effectively isolates the characteristic time of the charge transfer process,enabling a more precise determination of the reaction rate constant.Simulation results indicate that our approach reduces measurement errors to below 2%,closely aligning with theoretical values.Furthermore,experimental validation demonstrates an 80% reduction in error compared to the conventional galvanostatic intermittent titration technique(GITT)method.Overall,this study provides a novel voltage-based approach for determining the reaction rate constant,enhancing the applicability of theoretical analysis in electrode structural design and facilitating rapid battery optimization.展开更多
Objective:A TLCS method was established for the determination of the content of Shenbei Beigua ointment,and the product quality of six samples from two formulations was evaluated.Methods:The determination method was t...Objective:A TLCS method was established for the determination of the content of Shenbei Beigua ointment,and the product quality of six samples from two formulations was evaluated.Methods:The determination method was thin-layer chromatography scanning(TLCS),using a developing solvent composed of ethyl acetate–methanol–strong ammonia water(17:2:1).The plates were heated at 105°C for 5 minutes,then sprayed with a mixture of dilute bismuth potassium iodide and 1%ferric chloride in ethanol(10:1),and scanned at a wavelength of 500 nm.Results:Peimine showed good linearity in the concentration range of 0.21–2.1μg with a correlation coefficient of r=0.9997,and Peiminine also exhibited good linearity in the same range with r=0.9995.The accuracy was≥95.0%,and the relative standard deviation(RSD)was≤5.0%(n=6).Conclusion:This method allows for the simultaneous determination of peimine and peiminine,providing a reliable reference for the quality control of the product.展开更多
Fenton/Fenton-like reactions have gained popularity for their remarkable proficiency in decomposing organic pollutants,especially when enhanced by reductants addition for accel-erating the Fe2+regeneration.Nevertheles...Fenton/Fenton-like reactions have gained popularity for their remarkable proficiency in decomposing organic pollutants,especially when enhanced by reductants addition for accel-erating the Fe2+regeneration.Nevertheless,these works predominantly centered on the formation and utilization of hydroxyl radicals(•OH)in the process,neglecting the evolution of oxidant and reductant due to the difficulty in the simultaneous determination of these two components.By employing the quenching-iodometric method,we could simultaneously determine the concentrations of HSO_(3)-and peroxydisulfate(PDS).This method first employed an excess of peroxymonosulfate(PMS)to effectively quench HSO_(3)-,and then used the iodometric spectrophotometry to simultaneously determine the concentrations of PMS and PDS in the reaction system.Finally,through precise stoichiometric relationships,we could accurately calculate the concentration of HSO_(3)-.Based on this method,we achieved concentration measurements that,upon linear fitting,yielded a correlation coefficient(R^(2))surpassing 0.99,unequivocally affirming the method’s accuracy and trustworthiness.In this work,an innovation approach for determining the concentrations of HSO_(3)-(reductant)and PDS(oxidant)was explored.Additionally,the resilience of the method was verified across different pH levels and in the presence of diverse impurity ions.The results ensured precise concentration measure-ments in the real wastewater.This method was characterized by its simplicity,rapid analysis,and environmental friendliness,offering a newanalytical strategy for the determination of PDS and HSO_(3)-in environmental samples.The method enables more meticulous monitoring of chemical usage in water treatment,facilitating optimized dosing strategies and assessments of reductant-enhanced Fenton or Fenton-like system in water purification.展开更多
In paleoseismic research,defining the age of an event is relatively straightforward,but pinpointing its magnitude with precision is challenging.This difficulty primarily arises because physical parameters,such as rupt...In paleoseismic research,defining the age of an event is relatively straightforward,but pinpointing its magnitude with precision is challenging.This difficulty primarily arises because physical parameters,such as rupture area and displacement,which are intimately linked to the seismic moment,are hard to derive from paleoseismic studies.Our preceding study identified two earthquake sites in Huoshan and Guzhen,Anhui Province.While we qualitatively described the timing of these occurrences and the characteristics of sand veins,dislocations,and earthquake-induced cracks,we did not provide quantitative estimates of their magnitude or seismogenic faults.Consequently,these findings were insufficient for assessing regional seismic risks or determining the potential magnitude of specific faults.This study employs two empirical relationships:one between the farthest distribution distance based on liquefaction from earthquake-induced events and magnitude,and the other concerning the intensityepicenter distance-magnitude relationship.Through these relationships,we analyze the sandy soil liquefaction and earthquake-induced cracks quantitatively.The analysis includes magnitude estimation and seismogenic fault evaluation for the sandy soil liquefaction and crack remnants of the Huoshan Daijiayuan earthquake,as well as the dislocation and crack remnants of the Guzhen Gaixia earthquake.The findings indicate that the Huoshan Daijiayuan site records two paleoseismic events.The first event transpired after 850 BC,and the second after 550 BC,with a gap of approximately 300 years between them;both had a seismic magnitude(M_(S))of around 6.0.The likely seismogenic fault for the Huoshan Daijiayuan earthquake is the Luoerling-Tudiling fault.Meanwhile,the paleoseismic site in Guzhen Gaixia documents two seismic events occurring during 2350-2050 BC,both with a seismic magnitude(MS)of approximately 6½.The Tancheng-Lujiang fault zone is likely the seismogenic fault associated with the Guzhen Gaixia earthquake site.展开更多
Instantaneous Global Navigation Satellite System(GNSS)attitude determination method which achieves real-time attitude determination using GNSS signal has been extensively studied,particularly the one using a priori at...Instantaneous Global Navigation Satellite System(GNSS)attitude determination method which achieves real-time attitude determination using GNSS signal has been extensively studied,particularly the one using a priori attitude information replacing the code measurements to enhance the successful rate for ambiguity resolution.However,there exists a key limitation that this method relies on considerable Monte Carlo sampling particles to construct the pdf of ambiguities,resulting in significant computational burdens.To address this limitation,this paper provides a rapid single-epoch GNSS attitude determination method based on a priori attitude information.It utilizes a second-order Taylor expansion to analytically estimate the covariance of the baseline conditioned on a priori attitude information.This is followed by deriving the float solution and covariance of ambiguities,which are then processed using the standard LAMBDA method for integer ambiguity resolution.Experimental results demonstrate that our method is both efficient and accurate,significantly reducing computational costs compared to previous methods,thereby enhancing its applicability for GNSS-based attitude determination.展开更多
This study demonstrates the fabrication of mesoporous tungsten trioxide(WO_(3))-decorated flexible polyimide(PI)electrodes for the highly sensitive detection of catechol(CC)and hydroquinone(HQ),two environmental pollu...This study demonstrates the fabrication of mesoporous tungsten trioxide(WO_(3))-decorated flexible polyimide(PI)electrodes for the highly sensitive detection of catechol(CC)and hydroquinone(HQ),two environmental pollutants.Organic-inorganic composite dots are formed on flexible PI electrodes using evaporation-induced self-assembly(EISA)and electrospray methods.The EISA process is induced by a temperature gradient during electrospray,and the heated substrate partially decomposes the organic parts etched by O_(2) plasma,creating mesoporous structures.Differential pulse voltammetry and cyclic voltammetry demonstrate a linear correlation between analyte concentration and the electrochemical response.Computational studies support the spontaneous adsorption of CC and HQ molecules on model WO_(3) surfaces.The proposed sensor shows high sensitivity,a wide linear range,and a low detection limit for both individual and simultaneous determination of CC and HQ.Real sample analysis on river water confirms practical applicability.The WO_(3)-decorated PI electrode presents an efficient and reliable approach for detecting these pollutants,contributing to environmental safety measures.展开更多
The exploratory synthesis and structural characterization of twodimensional(2D)honeycomb structured Ru-based compounds are key focuses in inorganic materials research,due to the various exotic electronic states arisin...The exploratory synthesis and structural characterization of twodimensional(2D)honeycomb structured Ru-based compounds are key focuses in inorganic materials research,due to the various exotic electronic states arising from the interplay of electron correlations and spinorbit coupling.Among these compounds,α-RuCl_(3) and RuBr_(3) are considered as the most promising candidates for quantum spin liquid(QSL)materials[1–3].As a homolog,α-RuI3 has attracted significant interest,but it still remains relatively unexplored.Recently,it was synthesized by high-temperature and high-pressure solid-state reaction,but reported to be different crystal structures by independent groups.Ni et al.and Nawa et al.considerα-RuI3 to be R-3(3R)and P-31c(2H)space group,respectively[4,5].Both structures have typical 2D characteristics,in which the edge-sharing RuI6 octahedra form honeycomb layers stacked along the c-axis.The primary difference lies in that the honeycomb layers stack in ABCABC mode in the 3R phase,while in ABAB mode in the 2H phase(Fig.S1).Yang et al.discussed the stability of 3R and 2H polymorphs in terms of the total energies and dynamics,finding both structures are stable.However,the total energy of the 2H phase is slightly higher,2.58 meV than that of the 3R analog[6].When it comes to the conductivity behaviour,α-RuCl3 andα-RuBr_(3) are semiconductors as normally observed in QSL materials.In contrast,α-RuI_(3) exhibits metallic response.In 2D materials,the band structure may be drastically modified by altering the stacking order[7].Hence,determining the crystal structure ofα-RuI_(3) is urgently required,which is a key step in comprehensive and in-depth analysis of its physical properties.展开更多
Navigation satellites generally use satellite-ground and inter-satellite observation data for precise orbit determination.In orbit determination,the satellite position is often referenced to the satellite’s centroid,...Navigation satellites generally use satellite-ground and inter-satellite observation data for precise orbit determination.In orbit determination,the satellite position is often referenced to the satellite’s centroid,while the observational measurements are referenced to the satellite’s antenna phase center.The deviation between the satellite’s centroid and the antenna phase center forms the satellite antenna phase center error,which affects the precision of orbit determination.This paper takes a global navigation satellite system(GNSS)MEO satellite as an example and analyzes the actual situation of the satellite antenna phase center deviation and phase center variation based on the ground calibration data of the in-orbit satellite antenna phase center and the satellite’s in-orbit working status.The analysis shows that the antenna phase center variation caused by the satellite’s in-orbit operation is only at the centimeter level,which has a limited impact on orbit determination accuracy.The main source of precise orbit determination error is the satellite antenna phase center deviation,which can be corrected using ground calibration data.展开更多
[Objectives]To establish a multi-indicator quality control method for the retention of Longqing Capsule based on the principle of prescription of Chinese medicine.[Methods]High performance liquid chromatography(HPLC)w...[Objectives]To establish a multi-indicator quality control method for the retention of Longqing Capsule based on the principle of prescription of Chinese medicine.[Methods]High performance liquid chromatography(HPLC)with ShimNex CS C 18 as the column;column temperature:35℃;wavelength:270 nm;methanol-0.1%phosphoric acid solution as the mobile phase with gradient elution.[Results]The 12 components of the retention of Longqing Capsule showed good linearity within the investigated range(r≥0.9995),with the average spiked recoveries of 97.83%-100.52%and the RSD of 0.9%-2.1%.[Conclusions]The method is exclusive,sensitive,reproducible,simple and easy to use,and can provide a reference for the construction of the quality standard and control system of Longqing Capsule based on the theory of traditional Chinese medicine.展开更多
The deployment of the low earth orbit(LEO)satellites provides a large number of signals of opportunity(SOPs),unmanned aerial vehicle(UAV)positioning and navigation via LEO-SOPs have re-ceived much attention.Current re...The deployment of the low earth orbit(LEO)satellites provides a large number of signals of opportunity(SOPs),unmanned aerial vehicle(UAV)positioning and navigation via LEO-SOPs have re-ceived much attention.Current research is focused on Doppler positioning techniques,which require the collaboration of multiple satellites(≥3).However,the dynamic changes of LEO satellites weaken the generalization ability of Doppler positioning.In this paper,a direct position determination(DPD)method with uniform circular array(UCA)is proposed for UAV positioning from the perspective of the spatial spectrum estimation of LEO-SOPs.The proposed method employs the orthogonality between the signal and noise subspaces of the covariance matrix of the different received SOPs to establish the cost function for UAV’s coordinate.Instead of the multiple dimen-sional search,a root mean square propagation(RM-SProp)gradient optimizer with an adaptive learning rate is developed to find the coordinate of UAV.The effectiveness and robustness of the proposed method are verified using numerical data generated from the systems tool kit(STK).展开更多
Inspired by the recent discovery of breathing kagome materials Nb_(3)Cl_(8) and Nb_(3)TeCl_(7),we have explored the influence of the breathing effect on the Hubbard model of the kagome lattice.Utilizing the determinan...Inspired by the recent discovery of breathing kagome materials Nb_(3)Cl_(8) and Nb_(3)TeCl_(7),we have explored the influence of the breathing effect on the Hubbard model of the kagome lattice.Utilizing the determinant quantum Monte Carlo method,we first investigated the average sign problem in the breathing kagome lattice,which is influenced by both the breathing strength and the interaction strength.Secondly,we calculated the electronic kinetic energy,the direct current conductivity,and the electronic density of states at the Fermi level to determine the critical interaction strength for the metal-insulator transition.Our results indicate that the breathing effect,in conjunction with the interaction strength,drives the kagome system from a metal to an insulator.Finally,we evaluated the magnetic properties and constructed a phase diagram incorporating both transport and magnetic properties.The phase diagram reveals that as the interaction strength increases,the system transitions from a paramagnetic metal to a Mott insulator.Our research provides theoretical guidance for utilizing the breathing effect to control the band gaps,conductivity,and magnetic properties of kagome materials with electronic interactions.展开更多
基金supported by the National Natural Science Foundation of China(32325049,U22A20529,32303000)Zhejiang Provincial Natural Science Foundation(LQ24C190009)+1 种基金Ningbo Natural Science Foundation(2022J192)Zhejiang Provincial Top Key Discipline of Biological Engineering(1741000592)。
文摘In reptiles,such as the red-eared slider turtle(Trachemys scripta elegans),gonadal sex determination is highly dependent on the environmental temperature during embryonic stages.This complex process,which leads to differentiation into either testes or ovaries,is governed by the finely tuned expression of upstream genes,notably the testis-promoting gene Dmrt1 and the ovary-promoting gene Foxl2.Recent studies have identified epigenetic regulation as a crucial factor in testis development,with the H3K27me3 demethylase KDM6B being essential for Dmrt1 expression in T.s.elegans.However,whether KDM6B alone can induce testicular differentiation remains unclear.In this study,we found that overexpression of Kdm6b in T.s.elegans embryos induced the male development pathway,accompanied by a rapid increase in the gonadal expression of Dmrt1 at 31°C,a temperature typically resulting in female development.Notably,this sex reversal could be entirely rescued by Dmrt1 knockdown.These findings demonstrate that Kdm6b is sufficient for commitment to the male pathway,underscoring its role as a critical epigenetic regulator in the sex determination of the red-eared slider turtle.
文摘The refugee determination system directly affects whether or not an asylum seeker can obtain a country’s legal protection. The rational construction of China’s refugee determination system is not only the need to comply with China’s obligations under the International Refugee Convention, but also the requirement for the protection of the legitimate rights of refugees in China. Under the current framework of international law and domestic law, we should gradually improve China’s legal system of refugee status determination, and we should determine refugee screening agencies and define their division of labor and powers rationally, according to the actual situation of China. In the meantime, we should attach importance to undertaking China’s international obligations and strengthening international cooperation in refugee relief.
文摘As an important sensor in the navigation systems,star sensors and the gyro play important roles in spacecraft attitude determination system.Complex environmental factors are the main sources of error in attitude determination.The error influence of different benchmarks and the disintegration mode between the star sensor and the gyro is analyzed in theory.The integrated design of the star sensor and the gyro on the same benchmark can effectively avoid the error influence and improves the spacecraft attitude determination accuracy.Simulation results indicate that when the stars sensor optical axis vectors overlap the reference coordinate axis of the gyro in the same benchmark,the attitude determination accuracy improves.
基金the Astronautic Technology Foundation (HTZC0405)
文摘In view of the problem that the current single-antenna GPS attitude determination system can only determine the body attitude when the sideslip angle is zero and the multiantenna GPS/SINS integrated navigation system is of large volume, high cost, and complex structure, this approach is presented to determine the attitude based on vector space with single-antenna GPS and accelerometers in the micro inertial measurement unit （MIMU）. It can provide real-time and accurate attitude information. Subsequently, the single-antenna GPS/SINS integrated navigation system is designed based on the combination of position, velocity, and attitude. Finally the semi- physical simulations of single-antenna GPS attitude determination system and single-antenna GPS/SINS integrated navigation system are carried out. The simulation results, based on measured data, show that the single-antenna GPS/SINS system can provide more accurate navigation information compared to the GPS/SINS system, based on the combination of position and velocity. Furthermore, the single-antenna GPS/SINS system is characteristic of lower cost and simpler structure. It provides the basis for the application of a single-antenna GPS/SINS integrated navigation system in a micro aerial vehicle （MAV）.
文摘The Satellite Positioning and Orbit Determination System(SPODS)is a software package for GNSS positioning/orbit determination,developed by the Xi’an Research Institute of Surveying and Mapping.So far it has been able to analyse GPS data and has the capability of high precision GPS positioning and orbit determination.The underlying theory and the performance evaluation are briefly addressed in this paper.The experiments are carried out with GPS data collected from about 127 IGS stations during 4~10 January 2009.The results show that the RMS 1D difference is 1.1 cm between SPODS orbits and final IGS combined orbits,and that the repeatability of daily solutions of station coordinates is 1.5 mm for horizontal components,and 4.5 mm for vertical component,and that the consistency of ERP solutions with IGS final products is 0.025 mas,0.093 mas and 0.013 ms/d respectively for pole coordinates and LOD.
基金Sponsored by the China Postdoctoral Science Foundation(Grant No.2013M540857)the Fundamental Research Funds for the Central Universities(Grant No.FRF-TP-14-019A1)
文摘This paper discusses the design and implementation of a low cost multi-sensor integrated attitude determination system for small unmanned aerial vehicles( UAVs),which uses strapdown inertial navigation system( SINS) based on micro electromechanical system( MEMS) inertial sensors,commercial GPS receiver,and 3-axis magnetometer.MEMS-SINS initial attitude determination cannot be well performed for the reason that the MEMS inertial sensors biases are time-varying and poor repeatability,therefore in this paper the magnetometer and inclinometer are used to assist the MEMS-SINS initial attitude determination and MEMS inertial sensors field calibration.Furthermore,the attitude determination algorithms are presented to estimate the full attitude during GPS signal outage and non-accelerating situation.Additionally,the attitude information estimation results are compared with the reference of the non-magnetic marble platform and 3-axis turntable.Then the attitude estimation precision satisfies the requirement of attitude measurement for small UAVs during GPS signal outage and availability.Finally,the small UAV autonomous flight test results show that the low cost and real-time attitude determination system can yield continuous,reliable and effective attitude information for small UAVs.
基金the National Natural Science Foundation of China (Nos. U1867205, 21622508, and 21575092)Study on Physical/Chemical Characteristics Related to the Migration of Key Nuclides under Simulated Disposal Conditions (Phase Ⅱ) (Contract No. KGES 2019(170), dated February 21, 2019.) for financial support。
文摘Although inductively coupled plasma mass spectrometry(ICP-MS) retains high sensitivity and has been intensively used for the measurement of ^(99)Tc, it usually suffers from tedious, expensive, and timeconsuming sample pretreatments due to the isobaric interferences from ^(99)Ru and ^(98)Mo^(1)H. Herein, capillary electrophoresis(CE) was applied as sample introduction system for the sensitive, and interferencefree determination of ^(99)TcO_(4)^(-) from RuO_(4)^(-), and MoO_(4)^(2-) by ICP-MS with a simple sample treatment. Compared to the conventional methods, the hyphenated CE-ICP-MS avoids the use of expensive separation resins and reduces the consumption of mineral acid, representing a simpler, more efficient and environmentally benign approach. Moreover, the proposed method exhibits higher accuracy compared with the mathematical correction method using the natural isotope ratio of ^(99)Ru and ^(101)Ru, and significantly reduces sample consumption and the amount of waste, thus remarkably alleviating the radioactive exposure to operators and the pressure of radioactive waste treatment. Under the optimized conditions, the detection limits of 25 μg/L and 0.06 μg/L were obtained for RuO_(4)^(-) and ReO_(4)^(-)(Tc was replaced by Re), respectively, with relative standard deviation(RSD) lower than 5%. In addition, efficient recoveries of RuO_(4)^(-),ReO_(4)^(-),and ^(99)TcO_(4)^(-) from simulated Hanford site groundwater were achieved. The method is expected to be a promising candidate for sensitive and accurate analysis of ^(99)Tc from contaminated environmental samples.
文摘The deteriorated continuous rigid frame bridge is strengthened by external prestressing. Static loading tests wereconducted before and after the bridge rehabilitation to verify the effectiveness of the rehabilitation process. Thestiffness of the repaired bridge is improved, and the maximum deflection of the load test is reduced from 37.9 to27.6 mm. A bridge health monitoring system is installed after the bridge is reinforced. To achieve an easy assessmentof the bridge’s safety status by directly using transferred data, a real-time safety warning system is createdbased on a five-level safety standard. The threshold for each safety level will be determined by theoretical calculationsand the outcomes of static loading tests. The highest risk threshold will be set at the ultimate limit statevalue. The remaining levels, namely middle risk, low risk, and very low risk, will be determined usingreduction coefficients of 0.95, 0.9, and 0.8, respectively.
基金supported by the National Key R&D Program of China 2022YFB2404300the National Natural Science Foundation of China U22B2069the China Postdoctoral Science Foundation 2024M761006。
文摘The reaction rate constant is a crucial kinetic parameter that governs the charge and discharge performance of batteries,particularly in high-rate and thick-electrode applications.However,conventional estimation or fitting methods often overestimate the charge transfer overpotential,leading to substantial errors in reaction rate constant measurements.These inaccuracies hinder the accurate prediction of voltage profiles and overall cell performance.In this study,we propose the characteristic time-decomposed overpotential(CTDO)method,which employs a single-layer particle electrode(SLPE)structure to eliminate interference overpotentials.By leveraging the distribution of relaxation times(DRT),our method effectively isolates the characteristic time of the charge transfer process,enabling a more precise determination of the reaction rate constant.Simulation results indicate that our approach reduces measurement errors to below 2%,closely aligning with theoretical values.Furthermore,experimental validation demonstrates an 80% reduction in error compared to the conventional galvanostatic intermittent titration technique(GITT)method.Overall,this study provides a novel voltage-based approach for determining the reaction rate constant,enhancing the applicability of theoretical analysis in electrode structural design and facilitating rapid battery optimization.
文摘Objective:A TLCS method was established for the determination of the content of Shenbei Beigua ointment,and the product quality of six samples from two formulations was evaluated.Methods:The determination method was thin-layer chromatography scanning(TLCS),using a developing solvent composed of ethyl acetate–methanol–strong ammonia water(17:2:1).The plates were heated at 105°C for 5 minutes,then sprayed with a mixture of dilute bismuth potassium iodide and 1%ferric chloride in ethanol(10:1),and scanned at a wavelength of 500 nm.Results:Peimine showed good linearity in the concentration range of 0.21–2.1μg with a correlation coefficient of r=0.9997,and Peiminine also exhibited good linearity in the same range with r=0.9995.The accuracy was≥95.0%,and the relative standard deviation(RSD)was≤5.0%(n=6).Conclusion:This method allows for the simultaneous determination of peimine and peiminine,providing a reliable reference for the quality control of the product.
基金supported by National Natural Scienc Foundation of China(No.52400097)the Nanqiang Young Talents Supporting Program from Xiamen University.
文摘Fenton/Fenton-like reactions have gained popularity for their remarkable proficiency in decomposing organic pollutants,especially when enhanced by reductants addition for accel-erating the Fe2+regeneration.Nevertheless,these works predominantly centered on the formation and utilization of hydroxyl radicals(•OH)in the process,neglecting the evolution of oxidant and reductant due to the difficulty in the simultaneous determination of these two components.By employing the quenching-iodometric method,we could simultaneously determine the concentrations of HSO_(3)-and peroxydisulfate(PDS).This method first employed an excess of peroxymonosulfate(PMS)to effectively quench HSO_(3)-,and then used the iodometric spectrophotometry to simultaneously determine the concentrations of PMS and PDS in the reaction system.Finally,through precise stoichiometric relationships,we could accurately calculate the concentration of HSO_(3)-.Based on this method,we achieved concentration measurements that,upon linear fitting,yielded a correlation coefficient(R^(2))surpassing 0.99,unequivocally affirming the method’s accuracy and trustworthiness.In this work,an innovation approach for determining the concentrations of HSO_(3)-(reductant)and PDS(oxidant)was explored.Additionally,the resilience of the method was verified across different pH levels and in the presence of diverse impurity ions.The results ensured precise concentration measure-ments in the real wastewater.This method was characterized by its simplicity,rapid analysis,and environmental friendliness,offering a newanalytical strategy for the determination of PDS and HSO_(3)-in environmental samples.The method enables more meticulous monitoring of chemical usage in water treatment,facilitating optimized dosing strategies and assessments of reductant-enhanced Fenton or Fenton-like system in water purification.
基金supported by the Spark Program of Earthquake Sciences(No.XH23020YA)Joint Open Fund of Mengcheng National Geophysical Observatory(No.MEMGO-202411)Hefei government special technology research project(2024BFFFD02048).
文摘In paleoseismic research,defining the age of an event is relatively straightforward,but pinpointing its magnitude with precision is challenging.This difficulty primarily arises because physical parameters,such as rupture area and displacement,which are intimately linked to the seismic moment,are hard to derive from paleoseismic studies.Our preceding study identified two earthquake sites in Huoshan and Guzhen,Anhui Province.While we qualitatively described the timing of these occurrences and the characteristics of sand veins,dislocations,and earthquake-induced cracks,we did not provide quantitative estimates of their magnitude or seismogenic faults.Consequently,these findings were insufficient for assessing regional seismic risks or determining the potential magnitude of specific faults.This study employs two empirical relationships:one between the farthest distribution distance based on liquefaction from earthquake-induced events and magnitude,and the other concerning the intensityepicenter distance-magnitude relationship.Through these relationships,we analyze the sandy soil liquefaction and earthquake-induced cracks quantitatively.The analysis includes magnitude estimation and seismogenic fault evaluation for the sandy soil liquefaction and crack remnants of the Huoshan Daijiayuan earthquake,as well as the dislocation and crack remnants of the Guzhen Gaixia earthquake.The findings indicate that the Huoshan Daijiayuan site records two paleoseismic events.The first event transpired after 850 BC,and the second after 550 BC,with a gap of approximately 300 years between them;both had a seismic magnitude(M_(S))of around 6.0.The likely seismogenic fault for the Huoshan Daijiayuan earthquake is the Luoerling-Tudiling fault.Meanwhile,the paleoseismic site in Guzhen Gaixia documents two seismic events occurring during 2350-2050 BC,both with a seismic magnitude(MS)of approximately 6½.The Tancheng-Lujiang fault zone is likely the seismogenic fault associated with the Guzhen Gaixia earthquake site.
基金supported by the Research Grants Council of the Hong Kong Special Administrative Region,China(Nos.25202520,15214523)the Fundamental Research Funds for the Central Universities,China(No.YWF-22-L-805)。
文摘Instantaneous Global Navigation Satellite System(GNSS)attitude determination method which achieves real-time attitude determination using GNSS signal has been extensively studied,particularly the one using a priori attitude information replacing the code measurements to enhance the successful rate for ambiguity resolution.However,there exists a key limitation that this method relies on considerable Monte Carlo sampling particles to construct the pdf of ambiguities,resulting in significant computational burdens.To address this limitation,this paper provides a rapid single-epoch GNSS attitude determination method based on a priori attitude information.It utilizes a second-order Taylor expansion to analytically estimate the covariance of the baseline conditioned on a priori attitude information.This is followed by deriving the float solution and covariance of ambiguities,which are then processed using the standard LAMBDA method for integer ambiguity resolution.Experimental results demonstrate that our method is both efficient and accurate,significantly reducing computational costs compared to previous methods,thereby enhancing its applicability for GNSS-based attitude determination.
基金supported by the Basic Science Research Program through the National Research Foundation of Korea(NRF),funded by the Ministry of Education(RS-202300243390 and 2020R1A5A1018052)supported by the Basic Science Research Program through the National Research Foundation of Korea,funded by the Ministry of Education(2022R1A3B1078163)supported by the Technology Innovation Program(Publicprivate joint investment semiconductor R&D program[K-CHIPS])to foster high-quality human resources(RS-2023-00235484)funded by the Ministry of Trade,Industry&Energy(MOTIE,Korea)(1415187770)。
文摘This study demonstrates the fabrication of mesoporous tungsten trioxide(WO_(3))-decorated flexible polyimide(PI)electrodes for the highly sensitive detection of catechol(CC)and hydroquinone(HQ),two environmental pollutants.Organic-inorganic composite dots are formed on flexible PI electrodes using evaporation-induced self-assembly(EISA)and electrospray methods.The EISA process is induced by a temperature gradient during electrospray,and the heated substrate partially decomposes the organic parts etched by O_(2) plasma,creating mesoporous structures.Differential pulse voltammetry and cyclic voltammetry demonstrate a linear correlation between analyte concentration and the electrochemical response.Computational studies support the spontaneous adsorption of CC and HQ molecules on model WO_(3) surfaces.The proposed sensor shows high sensitivity,a wide linear range,and a low detection limit for both individual and simultaneous determination of CC and HQ.Real sample analysis on river water confirms practical applicability.The WO_(3)-decorated PI electrode presents an efficient and reliable approach for detecting these pollutants,contributing to environmental safety measures.
基金supported by the National Natural Science Foundation of China(No.22090041)the Program for Guangdong Introducing Innovative and Entrepreneurial Teams(No.2017ZT07C069)+1 种基金the Guangdong Basic and Applied Basic Research Foundation(No.2022B1515120014)the Natural Science Foundation of Zhejiang Province(No.LQ21A040010).
文摘The exploratory synthesis and structural characterization of twodimensional(2D)honeycomb structured Ru-based compounds are key focuses in inorganic materials research,due to the various exotic electronic states arising from the interplay of electron correlations and spinorbit coupling.Among these compounds,α-RuCl_(3) and RuBr_(3) are considered as the most promising candidates for quantum spin liquid(QSL)materials[1–3].As a homolog,α-RuI3 has attracted significant interest,but it still remains relatively unexplored.Recently,it was synthesized by high-temperature and high-pressure solid-state reaction,but reported to be different crystal structures by independent groups.Ni et al.and Nawa et al.considerα-RuI3 to be R-3(3R)and P-31c(2H)space group,respectively[4,5].Both structures have typical 2D characteristics,in which the edge-sharing RuI6 octahedra form honeycomb layers stacked along the c-axis.The primary difference lies in that the honeycomb layers stack in ABCABC mode in the 3R phase,while in ABAB mode in the 2H phase(Fig.S1).Yang et al.discussed the stability of 3R and 2H polymorphs in terms of the total energies and dynamics,finding both structures are stable.However,the total energy of the 2H phase is slightly higher,2.58 meV than that of the 3R analog[6].When it comes to the conductivity behaviour,α-RuCl3 andα-RuBr_(3) are semiconductors as normally observed in QSL materials.In contrast,α-RuI_(3) exhibits metallic response.In 2D materials,the band structure may be drastically modified by altering the stacking order[7].Hence,determining the crystal structure ofα-RuI_(3) is urgently required,which is a key step in comprehensive and in-depth analysis of its physical properties.
文摘Navigation satellites generally use satellite-ground and inter-satellite observation data for precise orbit determination.In orbit determination,the satellite position is often referenced to the satellite’s centroid,while the observational measurements are referenced to the satellite’s antenna phase center.The deviation between the satellite’s centroid and the antenna phase center forms the satellite antenna phase center error,which affects the precision of orbit determination.This paper takes a global navigation satellite system(GNSS)MEO satellite as an example and analyzes the actual situation of the satellite antenna phase center deviation and phase center variation based on the ground calibration data of the in-orbit satellite antenna phase center and the satellite’s in-orbit working status.The analysis shows that the antenna phase center variation caused by the satellite’s in-orbit operation is only at the centimeter level,which has a limited impact on orbit determination accuracy.The main source of precise orbit determination error is the satellite antenna phase center deviation,which can be corrected using ground calibration data.
基金Supported by Provincial University Scientific Research Platform Team Project of Guizhou Provincial Department of Education(Qianjiaoji[2022]No.010).
文摘[Objectives]To establish a multi-indicator quality control method for the retention of Longqing Capsule based on the principle of prescription of Chinese medicine.[Methods]High performance liquid chromatography(HPLC)with ShimNex CS C 18 as the column;column temperature:35℃;wavelength:270 nm;methanol-0.1%phosphoric acid solution as the mobile phase with gradient elution.[Results]The 12 components of the retention of Longqing Capsule showed good linearity within the investigated range(r≥0.9995),with the average spiked recoveries of 97.83%-100.52%and the RSD of 0.9%-2.1%.[Conclusions]The method is exclusive,sensitive,reproducible,simple and easy to use,and can provide a reference for the construction of the quality standard and control system of Longqing Capsule based on the theory of traditional Chinese medicine.
基金supported by Jiangsu Province Fron-tier Leading Technology Basic Research Project(BK20222013)partly supported by National Natural Science Foundation of China(No.62101251)+1 种基金Fundamental Research Funds for the Central Universities(No.NS20240240)partly supported by Post-graduate Research&Practice Innovation Program of NUAA(No.016001)。
文摘The deployment of the low earth orbit(LEO)satellites provides a large number of signals of opportunity(SOPs),unmanned aerial vehicle(UAV)positioning and navigation via LEO-SOPs have re-ceived much attention.Current research is focused on Doppler positioning techniques,which require the collaboration of multiple satellites(≥3).However,the dynamic changes of LEO satellites weaken the generalization ability of Doppler positioning.In this paper,a direct position determination(DPD)method with uniform circular array(UCA)is proposed for UAV positioning from the perspective of the spatial spectrum estimation of LEO-SOPs.The proposed method employs the orthogonality between the signal and noise subspaces of the covariance matrix of the different received SOPs to establish the cost function for UAV’s coordinate.Instead of the multiple dimen-sional search,a root mean square propagation(RM-SProp)gradient optimizer with an adaptive learning rate is developed to find the coordinate of UAV.The effectiveness and robustness of the proposed method are verified using numerical data generated from the systems tool kit(STK).
基金supported by the National Science Foundation of China(Grant No.12474218)Beijing Natural Science Foundation(Grant Nos.1242022 and 1252022).
文摘Inspired by the recent discovery of breathing kagome materials Nb_(3)Cl_(8) and Nb_(3)TeCl_(7),we have explored the influence of the breathing effect on the Hubbard model of the kagome lattice.Utilizing the determinant quantum Monte Carlo method,we first investigated the average sign problem in the breathing kagome lattice,which is influenced by both the breathing strength and the interaction strength.Secondly,we calculated the electronic kinetic energy,the direct current conductivity,and the electronic density of states at the Fermi level to determine the critical interaction strength for the metal-insulator transition.Our results indicate that the breathing effect,in conjunction with the interaction strength,drives the kagome system from a metal to an insulator.Finally,we evaluated the magnetic properties and constructed a phase diagram incorporating both transport and magnetic properties.The phase diagram reveals that as the interaction strength increases,the system transitions from a paramagnetic metal to a Mott insulator.Our research provides theoretical guidance for utilizing the breathing effect to control the band gaps,conductivity,and magnetic properties of kagome materials with electronic interactions.
