In order to meet the demand of high-precision heading angle transmission in the transfer alignment of inertial navigation system on moving base,the analytical function relationship between the hull deforma-tion and th...In order to meet the demand of high-precision heading angle transmission in the transfer alignment of inertial navigation system on moving base,the analytical function relationship between the hull deforma-tion and the turning angular velocity and angular acceleration was derived by using the classical beam theory based on the analysis of the equivalent load exerted by the hydrodynamic force and inertia force on the hull structure during the turning process under the combined action of the steering rudder mo-ment and wave force.The objective law between the angular motion and the azimuth deformation angle of the hull under the combined action of maneuvering and sea waves was revealed.Finally,the correc-tion coefficients were determined according to the left turn and right turn motions of the hull by using the measured data of the ship in the sea trial during the S-shape maneuvering navigation,and the az-imuth deformation angle correction was completed.The results indicated that the application of the Qu’s bending deformation correction formula could greatly reduce the influence of the hull flexural deforma-tion on the heading angle accuracy,meet the needs of high-precision heading angle transmission,and fully verify the correctness of the hull azimuth deformation law and the heading angle transmission er-ror correction theory.This theory and method provided technical support for establishing high-precision distributed digital reference in the field of transfer alignment of inertial navigation on moving base and the application of heading angle transfer of other shipborne equipment.展开更多
In the traditional unscented Kalman filter（UKF）,accuracy and robustness decline when uncertain disturbances exist in the practical system.To deal with the problem,a robust UKF algorithm based on an H-infinity norm i...In the traditional unscented Kalman filter（UKF）,accuracy and robustness decline when uncertain disturbances exist in the practical system.To deal with the problem,a robust UKF algorithm based on an H-infinity norm is proposed.In Krein space,a robust element is added in the simplified UKF so as to improve the algorithm.The filtering gain is adjusted by the robust element and in this way the performance of the robustness of the filtering algorithm is promoted.In the initial alignment process of the large heading misalignment angle of the strapdown inertial navigation system（SINS）,comparative studies are conducted on the robust UKF and the simplified UKF.The simulation results illustrate that compared with the simplified UKF,the robust UKF is more accurate,and the estimation error of heading misalignment decreases from 16.9＇ to 4.3＇.In short,the robust UKF can reduce the sensitivity to the system disturbances resulting in better performance.展开更多
目的:探讨经会阴超声测量宫颈长度(CL)及宫颈前角(ACA)对孕期经阴道宫颈环扎术后早产的预测价值。方法:收集2021年1月至2022年6月在郑州大学第一附属医院诊断为宫颈机能不全而行经阴道宫颈环扎术的单胎妊娠孕妇189例,环扎术前24 h内行...目的:探讨经会阴超声测量宫颈长度(CL)及宫颈前角(ACA)对孕期经阴道宫颈环扎术后早产的预测价值。方法:收集2021年1月至2022年6月在郑州大学第一附属医院诊断为宫颈机能不全而行经阴道宫颈环扎术的单胎妊娠孕妇189例,环扎术前24 h内行经会阴超声检查,测量CL及ACA。以CL和ACA为自变量,以是否早产为因变量,进行Logistic回归,构建联合预测模型。绘制ROC曲线,分析环扎术前CL、ACA及两者联合对早产的预测价值。结果:189例中,早产67例(35.4%)。早产组CL小于非早产组[27.00(15.00,34.00)mm vs 32.00(28.75,36.25)mm],ACA大于非早产组[(120.13±11.47)°vs(103.52±17.44)°](P均<0.05)。CL、ACA及两者联合预测环扎术后早产的AUC(95%CI)分别为0.679(0.596~0.762)、0.792(0.727~0.856)、0.813(0.749~0.877),ACA及CL联合ACA的AUC大于CL(P<0.05)。结论:经会阴超声测量ACA可辅助CL预测孕期经阴道宫颈环扎术后早产的发生。展开更多
Knee osteoarthritis(OA) is a progressive joint disease hallmarked by cartilage and bone breakdown and associated with changes to all of the tissues in the joint,ultimately causing pain,stiffness,deformity and disabili...Knee osteoarthritis(OA) is a progressive joint disease hallmarked by cartilage and bone breakdown and associated with changes to all of the tissues in the joint,ultimately causing pain,stiffness,deformity and disability in many people.Radiographs are commonly used for the clinical assessment of knee OA incidence and progression,and to assess for risk factors.One risk factor for the incidence and progression of knee OA is malalignment of the lower extremities(LE).The hipknee-ankle(HKA) angle,assessed from a full-length LE radiograph,is ideally used to assess LE alignment.Careful attention to LE positioning is necessary to obtain the most accurate measurement of the HKA angle.Since full-length LE radiographs are not always available,the femoral shaft-tibial shaft(FS-TS) angle may be calculated from a knee radiograph instead.However,the FS-TS angle is more variable than the HKA angle and it should be used with caution.Knee radiographs are used to assess the severity of knee OA and its progression.There are three types of ordinal grading scales for knee OA:global,composite and individual feature scales.Each grade on a global scale describes one or more features of knee OA.The entire description must be met for a specific grade to be assigned.The KellgrenLawrence scale is the most commonly-used global scale.Composite scales grade several features of knee OA individually and sum the grades to create a total score.One example is the compartmental grading scale for knee OA.Composite scales can respond to change in a variety of presentations of knee OA.Individual feature scales assess one or more OA features individually and do not calculate a total score.They are most often used to monitor change in one OA feature,commonly joint space narrowing.The most commonly-used individual feature scale is the OA Research Society International atlas.Each type of scale has its advantages;however,composite scales may offer greater content validity.Responsiveness to change is unknown for most scales and deserves further evaluation.展开更多
The irregularity is a key factor affecting the wheel-rail contact geometry relationship. In this paper, we calculated the wheel-rail contact points at typical sections and obtained the longitudinal variation of the wh...The irregularity is a key factor affecting the wheel-rail contact geometry relationship. In this paper, we calculated the wheel-rail contact points at typical sections and obtained the longitudinal variation of the wheel-rail geometry relationship with the trace line method. The profile of the key rail sections was matched by cubic spline curve, and the shape interpolation was realized in non-controlling sections. The results show that the roll angles at each typical section increases gradually with the enlargement of track alignment irregularity. When the flange contact occurs, the roll angle increases dramatically. Proper track alignment irregularity towards the switch rail improves the structure irregularity of the turnout.展开更多
We investigate the liquid-crystal （LC） alignment direction on photoalignment films formed from photosensitive polyester containing thrifluoromethyl moieties （PPDA） with various molecular weights by crossed polariz...We investigate the liquid-crystal （LC） alignment direction on photoalignment films formed from photosensitive polyester containing thrifluoromethyl moieties （PPDA） with various molecular weights by crossed polarized optical microscopy. It is found that LC alignment behaviour changes with molecular weight of PPDA. The LC alignment on PPDA irradiated films with the highest molecular weight is homogeneous, while those with low and intermediate molecular weights are homeotropic. However, surface morphologies show weak dependence on molecular weight. The surfaces are smooth and there is no clear morphological anisotropy on these aligned films observed by an atomic force microscope. The surface energies of the irradiated films are also measured by using an indirect contact-angle method where both surface energy and its polar component, increase with increasing molecular weight. Different polar surface energies can be considered as a main reason for different alignment characteristics.展开更多
Surface enhanced Raman scattering (SERS) spectroscopy was first utilized to study the photo-orientation behaviour of the photoreactive groups on a novel photo-alignment film surface and elucidate the generation mechan...Surface enhanced Raman scattering (SERS) spectroscopy was first utilized to study the photo-orientation behaviour of the photoreactive groups on a novel photo-alignment film surface and elucidate the generation mechanism of pretilt angle. The novel photo-alignment film was prepared by spin-coating a solution of ladderlike polysiloxane (LPS) bearing dual photoreactive group on an ITO surface and by irradiation with linear-polarized ultraviolet (LPUV) light A Si—H terminal compound (M) containing an identical photosensitive part has been used to fabricate a model film for SERS investigation.展开更多
文摘In order to meet the demand of high-precision heading angle transmission in the transfer alignment of inertial navigation system on moving base,the analytical function relationship between the hull deforma-tion and the turning angular velocity and angular acceleration was derived by using the classical beam theory based on the analysis of the equivalent load exerted by the hydrodynamic force and inertia force on the hull structure during the turning process under the combined action of the steering rudder mo-ment and wave force.The objective law between the angular motion and the azimuth deformation angle of the hull under the combined action of maneuvering and sea waves was revealed.Finally,the correc-tion coefficients were determined according to the left turn and right turn motions of the hull by using the measured data of the ship in the sea trial during the S-shape maneuvering navigation,and the az-imuth deformation angle correction was completed.The results indicated that the application of the Qu’s bending deformation correction formula could greatly reduce the influence of the hull flexural deforma-tion on the heading angle accuracy,meet the needs of high-precision heading angle transmission,and fully verify the correctness of the hull azimuth deformation law and the heading angle transmission er-ror correction theory.This theory and method provided technical support for establishing high-precision distributed digital reference in the field of transfer alignment of inertial navigation on moving base and the application of heading angle transfer of other shipborne equipment.
基金The National Basic Research Program of China (973 Program) (No. 613121010202)
文摘In the traditional unscented Kalman filter（UKF）,accuracy and robustness decline when uncertain disturbances exist in the practical system.To deal with the problem,a robust UKF algorithm based on an H-infinity norm is proposed.In Krein space,a robust element is added in the simplified UKF so as to improve the algorithm.The filtering gain is adjusted by the robust element and in this way the performance of the robustness of the filtering algorithm is promoted.In the initial alignment process of the large heading misalignment angle of the strapdown inertial navigation system（SINS）,comparative studies are conducted on the robust UKF and the simplified UKF.The simulation results illustrate that compared with the simplified UKF,the robust UKF is more accurate,and the estimation error of heading misalignment decreases from 16.9＇ to 4.3＇.In short,the robust UKF can reduce the sensitivity to the system disturbances resulting in better performance.
文摘目的:探讨经会阴超声测量宫颈长度(CL)及宫颈前角(ACA)对孕期经阴道宫颈环扎术后早产的预测价值。方法:收集2021年1月至2022年6月在郑州大学第一附属医院诊断为宫颈机能不全而行经阴道宫颈环扎术的单胎妊娠孕妇189例,环扎术前24 h内行经会阴超声检查,测量CL及ACA。以CL和ACA为自变量,以是否早产为因变量,进行Logistic回归,构建联合预测模型。绘制ROC曲线,分析环扎术前CL、ACA及两者联合对早产的预测价值。结果:189例中,早产67例(35.4%)。早产组CL小于非早产组[27.00(15.00,34.00)mm vs 32.00(28.75,36.25)mm],ACA大于非早产组[(120.13±11.47)°vs(103.52±17.44)°](P均<0.05)。CL、ACA及两者联合预测环扎术后早产的AUC(95%CI)分别为0.679(0.596~0.762)、0.792(0.727~0.856)、0.813(0.749~0.877),ACA及CL联合ACA的AUC大于CL(P<0.05)。结论:经会阴超声测量ACA可辅助CL预测孕期经阴道宫颈环扎术后早产的发生。
文摘Knee osteoarthritis(OA) is a progressive joint disease hallmarked by cartilage and bone breakdown and associated with changes to all of the tissues in the joint,ultimately causing pain,stiffness,deformity and disability in many people.Radiographs are commonly used for the clinical assessment of knee OA incidence and progression,and to assess for risk factors.One risk factor for the incidence and progression of knee OA is malalignment of the lower extremities(LE).The hipknee-ankle(HKA) angle,assessed from a full-length LE radiograph,is ideally used to assess LE alignment.Careful attention to LE positioning is necessary to obtain the most accurate measurement of the HKA angle.Since full-length LE radiographs are not always available,the femoral shaft-tibial shaft(FS-TS) angle may be calculated from a knee radiograph instead.However,the FS-TS angle is more variable than the HKA angle and it should be used with caution.Knee radiographs are used to assess the severity of knee OA and its progression.There are three types of ordinal grading scales for knee OA:global,composite and individual feature scales.Each grade on a global scale describes one or more features of knee OA.The entire description must be met for a specific grade to be assigned.The KellgrenLawrence scale is the most commonly-used global scale.Composite scales grade several features of knee OA individually and sum the grades to create a total score.One example is the compartmental grading scale for knee OA.Composite scales can respond to change in a variety of presentations of knee OA.Individual feature scales assess one or more OA features individually and do not calculate a total score.They are most often used to monitor change in one OA feature,commonly joint space narrowing.The most commonly-used individual feature scale is the OA Research Society International atlas.Each type of scale has its advantages;however,composite scales may offer greater content validity.Responsiveness to change is unknown for most scales and deserves further evaluation.
基金supported by the National Natural Science Foundation (No. 51008256)the Technological Research and Development Programsof the Ministry of Railways (No. 2010G006-B)
文摘The irregularity is a key factor affecting the wheel-rail contact geometry relationship. In this paper, we calculated the wheel-rail contact points at typical sections and obtained the longitudinal variation of the wheel-rail geometry relationship with the trace line method. The profile of the key rail sections was matched by cubic spline curve, and the shape interpolation was realized in non-controlling sections. The results show that the roll angles at each typical section increases gradually with the enlargement of track alignment irregularity. When the flange contact occurs, the roll angle increases dramatically. Proper track alignment irregularity towards the switch rail improves the structure irregularity of the turnout.
基金Supported by the National Natural Science Foundation of China under Grant Nos 60277033 and 50473040, and the Science Foundation of Jilin Province under Grant Nos 20020603 and 20050520.
文摘We investigate the liquid-crystal （LC） alignment direction on photoalignment films formed from photosensitive polyester containing thrifluoromethyl moieties （PPDA） with various molecular weights by crossed polarized optical microscopy. It is found that LC alignment behaviour changes with molecular weight of PPDA. The LC alignment on PPDA irradiated films with the highest molecular weight is homogeneous, while those with low and intermediate molecular weights are homeotropic. However, surface morphologies show weak dependence on molecular weight. The surfaces are smooth and there is no clear morphological anisotropy on these aligned films observed by an atomic force microscope. The surface energies of the irradiated films are also measured by using an indirect contact-angle method where both surface energy and its polar component, increase with increasing molecular weight. Different polar surface energies can be considered as a main reason for different alignment characteristics.
基金This work was supported by the National Natural Science Foundation of China (No. 50073028, 29974036, 20174047).
文摘Surface enhanced Raman scattering (SERS) spectroscopy was first utilized to study the photo-orientation behaviour of the photoreactive groups on a novel photo-alignment film surface and elucidate the generation mechanism of pretilt angle. The novel photo-alignment film was prepared by spin-coating a solution of ladderlike polysiloxane (LPS) bearing dual photoreactive group on an ITO surface and by irradiation with linear-polarized ultraviolet (LPUV) light A Si—H terminal compound (M) containing an identical photosensitive part has been used to fabricate a model film for SERS investigation.
