The time-domain calculations of retard function and ship motions in waves by the direct time-domain method （DTM） and the frequency to time-domain transformation method （FTTM） are compared and analyzed. A Wigley-hu...The time-domain calculations of retard function and ship motions in waves by the direct time-domain method （DTM） and the frequency to time-domain transformation method （FTTM） are compared and analyzed. A Wigley-hull-form ship and an $60 ship moving in waves are examined, and the corresponding retard functions are in good agreement with those given by DTM and FTTM. The comparison of retard functions in different forward speeds by the two methods is observed, and the results of ship motions in forward speed are also compared with the experimental data. On this basis, the advantage and disadvantage of them are discussed.展开更多
The key concept of spectrum response estimation with commercial software,such as the SESAM software tool,typically includes two main steps:finding a suitable loading spectrum and computing the response amplitude opera...The key concept of spectrum response estimation with commercial software,such as the SESAM software tool,typically includes two main steps:finding a suitable loading spectrum and computing the response amplitude operators(RAOs) subjected to a frequency-specified wave component.In this paper,we propose a nontraditional spectrum response estimation method that uses a numerical representation of the retardation functions.Based on estimated added mass and damping matrices of the structure,we decompose and replace the convolution terms with a series of poles and corresponding residues in the Laplace domain.Then,we estimate the power density corresponding to each frequency component using the improved periodogram method.The advantage of this approach is that the frequency-dependent motion equations in the time domain can be transformed into the Laplace domain without requiring Laplace-domain expressions for the added mass and damping.To validate the proposed method,we use a numerical semi-submerged pontoon from the SESAM.The numerical results show that the responses of the proposed method match well with those obtained from the traditional method.Furthermore,the estimated spectrum also matches well,which indicates its potential application to deep-water floating structures.展开更多
Sufficient conditions for the stability with respect to part of the functional differential equation variables are given. These conditions utilize Lyapunov functions to determine the uniform stability and uniform asym...Sufficient conditions for the stability with respect to part of the functional differential equation variables are given. These conditions utilize Lyapunov functions to determine the uniform stability and uniform asymptotic stability of functional differential equations. These conditions for the partial stability develop the Razumikhin theorems on uniform stability and uniform asymptotic stability of functional differential equations. An example is presented which demonstrates these results and gives insight into the new stability conditions.展开更多
The synergistic effect of conventional flame-retardant elements and graphene has received extensive attention in the development of a new class of flame retardants. Compared to covalent modification, the noncovalent s...The synergistic effect of conventional flame-retardant elements and graphene has received extensive attention in the development of a new class of flame retardants. Compared to covalent modification, the noncovalent strategy is simpler and expeditious and entirely preserves the original quality of graphene. Thus, non-covalently functionalized graphene oxide(FGO) with a phosphorus–nitrogen compound was successfully prepared via a one-pot process in this study. Polyethyleneimine and FGO were alternatively deposited on the surface of a poly(vinyl alcohol)(PVA) film via layer-by-layer assembly driven by electrostatic interaction, imparting excellent flame retardancy to the coated PVA film. The multilayer FGO-based coating formed a protective shield encapsulating the PVA matrix, effectively blocking the transfer of heat and mass during combustion. The coated PVA has a higher initial decomposition temperature of about 260 °C and a nearly 60% reduction in total heat release than neat PVA does. Our results may have a promising prospect for flame-retardant polymers.展开更多
BACKGROUND： In clinical practice, the degree of cognitive competence damage correlates to fine motor function deficits in children with psychomotor development retardation. Clear correlations between the two can help...BACKGROUND： In clinical practice, the degree of cognitive competence damage correlates to fine motor function deficits in children with psychomotor development retardation. Clear correlations between the two can help to develop and perform corresponding functional training for children with mental retardation （MR）. OBJECTIVE： This study was designed to evaluate and analyze the correlation of fine motor function to cognitive competence in MR children using the Peabody Developmental Motor Scale-Fine Motor （PDMS-FM） and Symbolic Play Test. DESIGN： Scale evaluation and correlation analysis. SETTING： Children＇s Rehabilitation Center ＆ Huajing District Hospital, Children＇s Hospital Affiliated to Fudan University. PARTICIPANTS： A total of 42 MR children, 28 males and 14 females, aged 14-69 months, were admitted to the Rehabilitation Center, Children＇s Hospital, Fudan University between June 2003 and April 2006, and were recruited for this study. All children corresponded to MR diagnosis criteria determined by Chinese Neurology and Psychiatry Society in 1989. Written informed consent for participating in the evaluation and for evaluated content was obtained from each child＇s guardian. METHODS： Subsequent to admission and prior to treatment, fine motor function of each MR child was evaluated using PDMS-FM （Chinese version）. The scale captured 98 items that formed the grasping （Gr） and visual-motor integration （Vi） subtests. Cognitive competence was evaluated using the Symbolic Play Test （Chinese version）, which captured four 6-item specific contents. The original score of each subtest was used to evaluate results for statistical analysis. Higher scores from the two evaluations indicated stronger abilities. Pearson correlation analysis was applied for analyzing data correlation. MAIN OUTCOME MEASURES： Fine motor function was evaluated using PDMS-FM. Cognitive competence was measured using the Symbolic Play Test. Correlations between results from the two evaluations were analyzed. RESULTS： All 42 MR children were included in the final analysis. Correlation analysis results demonstrated significant positive correlations of original scores existed between Gr and Vi subtests in the PDMS-FM （r = 0.761, P 〈 0.01）, and between Vi and Gr subtests in PDMS-FM and Symbolic Play Test （r = 0.663, 0.450, P 〈 0.01）. CONCLUSION： Fine motor function closely correlates to cognitive competence in MR children. This indicates fine motor function training should be developed in combination with cognitive competence training.展开更多
In this paper. four sufficiency theorems of existence of periodic solutions for aclass of retarded functional differential equations are given. The result of thesetheorems is better than the well-known Yoshizawa’s p...In this paper. four sufficiency theorems of existence of periodic solutions for aclass of retarded functional differential equations are given. The result of thesetheorems is better than the well-known Yoshizawa’s periodic solution theorem. Anexample of application is given at the end.展开更多
Maternal diabetes constitutes an unfavorable environment for embryonic and fetoplacental development. Despite current treatments, pregnant women with pregestational diabetes are at increased risk for congenital malfor...Maternal diabetes constitutes an unfavorable environment for embryonic and fetoplacental development. Despite current treatments, pregnant women with pregestational diabetes are at increased risk for congenital malformations, materno-fetal complications, placental abnormalities and intrauterine malprogramming. The complications during pregnancy concern the mother (gravidic hypertension and/or preeclampsia, cesarean section) and the fetus (macrosomia or intrauterine growth restriction, shoulder dystocia, hypoglycemia and respiratory distress). The fetoplacental impairment and intrauterine programming of diseases in the offspring's later life induced by gestational diabetes are similar to those induced by type 1 and type 2 diabetes mellitus. Despite the existence of several developmental and morphological differences in the placenta from rodents and women, there are similarities in the alterations induced by maternal diabetes in the placenta from diabetic patients and diabetic experimental models. From both human and rodent diabetic experimentalmodels, it has been suggested that the placenta is a compromised target that largely suffers the impact of maternal diabetes. Depending on the maternal metabolic and proin ammatory derangements, macrosomia is explained by an excessive availability of nutrients and an increase in fetal insulin release, a phenotype related to the programming of glucose intolerance. The degree of fetal damage and placental dysfunction and the availability and utilisation of fetal substrates can lead to the induction of macrosomia or intrauterine growth restriction. In maternal diabetes, both the maternal environment and the genetic background are important in the complex and multifactorial processes that induce damage to the embryo, the placenta, the fetus and the offspring. Nevertheless, further research is needed to better understand the mechanisms that govern the early embryo development, the induction of congenital anomalies and fetal overgrowth in maternal diabetes.展开更多
采用热重分析仪研究环氧树脂(EP)、含膨胀阻燃剂的环氧树脂(EP/IFR)以及添加纳米层状二硫化钼(MDNs)和鳞片石墨纳米片(FGNs)的环氧树脂/膨胀阻燃剂复合材料(EP/IFR/MDNs/FGNs)的热降解过程。比较IFR以及MDNs/FGNs与IFR的协效作用对EP热...采用热重分析仪研究环氧树脂(EP)、含膨胀阻燃剂的环氧树脂(EP/IFR)以及添加纳米层状二硫化钼(MDNs)和鳞片石墨纳米片(FGNs)的环氧树脂/膨胀阻燃剂复合材料(EP/IFR/MDNs/FGNs)的热降解过程。比较IFR以及MDNs/FGNs与IFR的协效作用对EP热稳定性及其热降解过程的影响。使用Starink法、Broido法和Phadnis法计算3种材料的热降解动力学活化能。结果表明:使用MDNs/FGNs与IFR协效阻燃可以显著提高材料的热稳定性,材料在800℃的残炭率显著提升。Starink法得到的活化能分别为166.03、163.68、158.02 k J/mol;Broido法得到的活化能为93.37、58.41、56.81 k J/mol;Phadnis法得到的活化能为59.71、36.58、35.52 k J/mol。通过Phadnis法确定了反应的机理函数。展开更多
文摘The time-domain calculations of retard function and ship motions in waves by the direct time-domain method （DTM） and the frequency to time-domain transformation method （FTTM） are compared and analyzed. A Wigley-hull-form ship and an $60 ship moving in waves are examined, and the corresponding retard functions are in good agreement with those given by DTM and FTTM. The comparison of retard functions in different forward speeds by the two methods is observed, and the results of ship motions in forward speed are also compared with the experimental data. On this basis, the advantage and disadvantage of them are discussed.
基金the financial support of the National Natural Science Foundation of China(Nos.5152 2906,51479184,51609219)the Excellent Youth Foundation of Shandong Scientific Committee(No.JQ201512)the Taishan Scholars Program of Shandong Province
文摘The key concept of spectrum response estimation with commercial software,such as the SESAM software tool,typically includes two main steps:finding a suitable loading spectrum and computing the response amplitude operators(RAOs) subjected to a frequency-specified wave component.In this paper,we propose a nontraditional spectrum response estimation method that uses a numerical representation of the retardation functions.Based on estimated added mass and damping matrices of the structure,we decompose and replace the convolution terms with a series of poles and corresponding residues in the Laplace domain.Then,we estimate the power density corresponding to each frequency component using the improved periodogram method.The advantage of this approach is that the frequency-dependent motion equations in the time domain can be transformed into the Laplace domain without requiring Laplace-domain expressions for the added mass and damping.To validate the proposed method,we use a numerical semi-submerged pontoon from the SESAM.The numerical results show that the responses of the proposed method match well with those obtained from the traditional method.Furthermore,the estimated spectrum also matches well,which indicates its potential application to deep-water floating structures.
基金Supported by the National Natural Science Foundation of China(Grant No.11171014)
文摘Sufficient conditions for the stability with respect to part of the functional differential equation variables are given. These conditions utilize Lyapunov functions to determine the uniform stability and uniform asymptotic stability of functional differential equations. These conditions for the partial stability develop the Razumikhin theorems on uniform stability and uniform asymptotic stability of functional differential equations. An example is presented which demonstrates these results and gives insight into the new stability conditions.
基金supported by National Natural Science Foundation of China (No. 51473095)the Program of Innovative Research Team for Young Scientists of Sichuan Province (2016TD0010)
文摘The synergistic effect of conventional flame-retardant elements and graphene has received extensive attention in the development of a new class of flame retardants. Compared to covalent modification, the noncovalent strategy is simpler and expeditious and entirely preserves the original quality of graphene. Thus, non-covalently functionalized graphene oxide(FGO) with a phosphorus–nitrogen compound was successfully prepared via a one-pot process in this study. Polyethyleneimine and FGO were alternatively deposited on the surface of a poly(vinyl alcohol)(PVA) film via layer-by-layer assembly driven by electrostatic interaction, imparting excellent flame retardancy to the coated PVA film. The multilayer FGO-based coating formed a protective shield encapsulating the PVA matrix, effectively blocking the transfer of heat and mass during combustion. The coated PVA has a higher initial decomposition temperature of about 260 °C and a nearly 60% reduction in total heat release than neat PVA does. Our results may have a promising prospect for flame-retardant polymers.
文摘BACKGROUND： In clinical practice, the degree of cognitive competence damage correlates to fine motor function deficits in children with psychomotor development retardation. Clear correlations between the two can help to develop and perform corresponding functional training for children with mental retardation （MR）. OBJECTIVE： This study was designed to evaluate and analyze the correlation of fine motor function to cognitive competence in MR children using the Peabody Developmental Motor Scale-Fine Motor （PDMS-FM） and Symbolic Play Test. DESIGN： Scale evaluation and correlation analysis. SETTING： Children＇s Rehabilitation Center ＆ Huajing District Hospital, Children＇s Hospital Affiliated to Fudan University. PARTICIPANTS： A total of 42 MR children, 28 males and 14 females, aged 14-69 months, were admitted to the Rehabilitation Center, Children＇s Hospital, Fudan University between June 2003 and April 2006, and were recruited for this study. All children corresponded to MR diagnosis criteria determined by Chinese Neurology and Psychiatry Society in 1989. Written informed consent for participating in the evaluation and for evaluated content was obtained from each child＇s guardian. METHODS： Subsequent to admission and prior to treatment, fine motor function of each MR child was evaluated using PDMS-FM （Chinese version）. The scale captured 98 items that formed the grasping （Gr） and visual-motor integration （Vi） subtests. Cognitive competence was evaluated using the Symbolic Play Test （Chinese version）, which captured four 6-item specific contents. The original score of each subtest was used to evaluate results for statistical analysis. Higher scores from the two evaluations indicated stronger abilities. Pearson correlation analysis was applied for analyzing data correlation. MAIN OUTCOME MEASURES： Fine motor function was evaluated using PDMS-FM. Cognitive competence was measured using the Symbolic Play Test. Correlations between results from the two evaluations were analyzed. RESULTS： All 42 MR children were included in the final analysis. Correlation analysis results demonstrated significant positive correlations of original scores existed between Gr and Vi subtests in the PDMS-FM （r = 0.761, P 〈 0.01）, and between Vi and Gr subtests in PDMS-FM and Symbolic Play Test （r = 0.663, 0.450, P 〈 0.01）. CONCLUSION： Fine motor function closely correlates to cognitive competence in MR children. This indicates fine motor function training should be developed in combination with cognitive competence training.
文摘In this paper. four sufficiency theorems of existence of periodic solutions for aclass of retarded functional differential equations are given. The result of thesetheorems is better than the well-known Yoshizawa’s periodic solution theorem. Anexample of application is given at the end.
文摘Maternal diabetes constitutes an unfavorable environment for embryonic and fetoplacental development. Despite current treatments, pregnant women with pregestational diabetes are at increased risk for congenital malformations, materno-fetal complications, placental abnormalities and intrauterine malprogramming. The complications during pregnancy concern the mother (gravidic hypertension and/or preeclampsia, cesarean section) and the fetus (macrosomia or intrauterine growth restriction, shoulder dystocia, hypoglycemia and respiratory distress). The fetoplacental impairment and intrauterine programming of diseases in the offspring's later life induced by gestational diabetes are similar to those induced by type 1 and type 2 diabetes mellitus. Despite the existence of several developmental and morphological differences in the placenta from rodents and women, there are similarities in the alterations induced by maternal diabetes in the placenta from diabetic patients and diabetic experimental models. From both human and rodent diabetic experimentalmodels, it has been suggested that the placenta is a compromised target that largely suffers the impact of maternal diabetes. Depending on the maternal metabolic and proin ammatory derangements, macrosomia is explained by an excessive availability of nutrients and an increase in fetal insulin release, a phenotype related to the programming of glucose intolerance. The degree of fetal damage and placental dysfunction and the availability and utilisation of fetal substrates can lead to the induction of macrosomia or intrauterine growth restriction. In maternal diabetes, both the maternal environment and the genetic background are important in the complex and multifactorial processes that induce damage to the embryo, the placenta, the fetus and the offspring. Nevertheless, further research is needed to better understand the mechanisms that govern the early embryo development, the induction of congenital anomalies and fetal overgrowth in maternal diabetes.
文摘采用热重分析仪研究环氧树脂(EP)、含膨胀阻燃剂的环氧树脂(EP/IFR)以及添加纳米层状二硫化钼(MDNs)和鳞片石墨纳米片(FGNs)的环氧树脂/膨胀阻燃剂复合材料(EP/IFR/MDNs/FGNs)的热降解过程。比较IFR以及MDNs/FGNs与IFR的协效作用对EP热稳定性及其热降解过程的影响。使用Starink法、Broido法和Phadnis法计算3种材料的热降解动力学活化能。结果表明:使用MDNs/FGNs与IFR协效阻燃可以显著提高材料的热稳定性,材料在800℃的残炭率显著提升。Starink法得到的活化能分别为166.03、163.68、158.02 k J/mol;Broido法得到的活化能为93.37、58.41、56.81 k J/mol;Phadnis法得到的活化能为59.71、36.58、35.52 k J/mol。通过Phadnis法确定了反应的机理函数。
