Asymmetric plate impact experiments are conducted on LY12 aluminium alloy in a pressure range of 85-131 GPa. The longitudinal sound speeds axe obtained from the time-resolved particle speed profiles of the specimen me...Asymmetric plate impact experiments are conducted on LY12 aluminium alloy in a pressure range of 85-131 GPa. The longitudinal sound speeds axe obtained from the time-resolved particle speed profiles of the specimen measured with Velocity Interferometer System for Any Reflector （VISAR） technique, and they are shown to be good agreement with our previously reported data of this alloy in a pressure range of 20-70 GPa, and also with those of 2024 aluminium reported by McQueen. Using all of the longitudinal speeds and the corresponding bulk speeds calculated from the Gruneisen equation of state （EOS）, shear moduli of LY12 aluminium alloy are obtained. A comparison of the shear moduli in the solid phase region with those estimated from the Steinberg model demonstrate that the latter are systematically lower than the measurements. By re-analysing the pressure effect on the shear modulus, a modified equation is proposed, in which the pressure term of P/η^1/3 in the Steinberg model is replaced by a linear term. Good agreement between experiments and the modified equation is obtained, which implies that the shear modulus of LY12 aluminium varies linearly both with pressure and with temperature throughout the whole solid phase region. On the other hand, shear modulus of aluminium in a solid-liquid mixed phrase region decreases gradually and smoothly, a feature that is very different from the drastic dropping at the melting point under static conditions.展开更多
As the web-server based business is rapidly developed and popularized, how to evaluate and improve the reliability of web-servers has been extremely important. Although a large num- ber of software reliability growth ...As the web-server based business is rapidly developed and popularized, how to evaluate and improve the reliability of web-servers has been extremely important. Although a large num- ber of software reliability growth models （SRGMs）, including those combined with multiple change-points （CPs）, have been available, these conventional SRGMs cannot be directly applied to web soft- ware reliability analysis because of the complex web operational profile. To characterize the web operational profile precisely, it should be realized that the workload of a web server is normally non-homogeneous and often observed with the pattern of random impulsive shocks. A web software reliability model with random im- pulsive shocks and its statistical analysis method are developed. In the proposed model, the web server workload is characterized by a geometric Brownian motion process. Based on a real data set from IIS server logs of ICRMS website （www.icrms.cn）, the proposed model is demonstrated to be powerful for estimating impulsive shocks and web software reliability.展开更多
<div style="text-align:justify;"> <strong>Objective</strong>: The work aimed to describe the etiological and evolutionary aspects of cardiogenic shock in the intensive care unit of the card...<div style="text-align:justify;"> <strong>Objective</strong>: The work aimed to describe the etiological and evolutionary aspects of cardiogenic shock in the intensive care unit of the cardiology department (USIC) of the G-spot hospital in Bamako,<span "=""> Mali. <b>Materials and Methods</b></span><span "="">: This was a descriptive cross-sectional study from January 1, 2018 to April 30, 2019 that included all patients admitted to the USIC during this period. Each patient benefited from individual data support with systematic recording of socio-demographic, clinical, complementary and therapeutic data and analyzed with the SOFTWARE SPSS 20.0 French version. <b>Results</b>: The study involved 40 patients out of 311 patients hospitalized in USIC, representing a hospital frequency of 12.86%. Males were the most affected (60%) with a sex ratio of 1.50. The modal class was 41</span> - 60 years with extremes at 18 years and 89 years. Cardiovascular risk factors were dominated by HTA (27.50%), diabetes and tobacco, each with 22.50%. The general signs were tachycardia (90%), oxygen desaturation (77.50%), impregnable blood pressure (62.50%), agitation (52.50%) and an oliguria (70%). At the electrocardiogram the rhythm was sinus (80%), it was an atrial fibrillation (15%), a ventricular tachycardia (10%) and signs of coronary ischemia (necrosis in 35% and ST over shifted in 20% of cases). At cardiac doppler ultrasound,the left ventricle was dilated (50%), the right cavities dilated (30%), segmental kinetic disorder (40%), the left ventricular systolic function (FEVG) impaired (75%) and valve disease (10%). Biology noted hyper-creatinemia (65%), hyper-glycemia (12.50%), anemia and hyponatremia with 20% frequency each. Among etiology,<span "=""> ischemic heart disease accounted for 57.50% followed by pulmonary embolism 20%, dilated valve cardiomyopathy 7.50% and chronic pulmonary heart 2.50%. The trend in the majority of cases was unfavorable with 60% of deaths. Chronic pulmonary heart and pulmonary embolism were the deadliest with a frequency of 100% and 87.50% respectively. <b>Conclusion</b>: Cardiogenic shock is an infrequent condition with a high mortality of a prognosis. Ischemic heart disease is the most common etiology of the disease</span>. </div>展开更多
A vibrational formulation, a technique, and an algorithm are proposed for assessing the resonance state of a package of rectangular plates and shells having point bonds and concentrated masses with different rheologic...A vibrational formulation, a technique, and an algorithm are proposed for assessing the resonance state of a package of rectangular plates and shells having point bonds and concentrated masses with different rheological properties of deformable elements under the influence of harmonic influences. The viscoelastic properties of elements are described using the linear Boltzmann-Volterra theory. An algebraic system of equations with complex coefficients is obtained, which is solved by the Gauss method. Various problems on steady-state forced vibrations for structurally inhomogeneous mechanical systems consisting of a package of plate and shell systems with concentrated masses and shock absorbers installed in it were solved. A number of new mechanical effects have been discovered associated with a decrease in the maximum resonance amplitudes of the mechanical system as a whole. The concept of “global resonance amplitude” is introduced to study the behavior of the resonance amplitudes of a mechanical system. An analysis of the numerical results showed that the interaction of resonant amplitudes is observed only in structurally inhomogeneous systems (in this case, with elastic and viscoelastic elements) and with a noticeable approximation of the natural frequencies.展开更多
基金Project supported by the National Natural Science Foundation of China (Grant Nos 10232040 and 10672149)the foundation of Laboratory for Shock Wave and Detonation Physics Research, China Academy of Engineering Physics (Grant No 9140C6702020603)
文摘Asymmetric plate impact experiments are conducted on LY12 aluminium alloy in a pressure range of 85-131 GPa. The longitudinal sound speeds axe obtained from the time-resolved particle speed profiles of the specimen measured with Velocity Interferometer System for Any Reflector （VISAR） technique, and they are shown to be good agreement with our previously reported data of this alloy in a pressure range of 20-70 GPa, and also with those of 2024 aluminium reported by McQueen. Using all of the longitudinal speeds and the corresponding bulk speeds calculated from the Gruneisen equation of state （EOS）, shear moduli of LY12 aluminium alloy are obtained. A comparison of the shear moduli in the solid phase region with those estimated from the Steinberg model demonstrate that the latter are systematically lower than the measurements. By re-analysing the pressure effect on the shear modulus, a modified equation is proposed, in which the pressure term of P/η^1/3 in the Steinberg model is replaced by a linear term. Good agreement between experiments and the modified equation is obtained, which implies that the shear modulus of LY12 aluminium varies linearly both with pressure and with temperature throughout the whole solid phase region. On the other hand, shear modulus of aluminium in a solid-liquid mixed phrase region decreases gradually and smoothly, a feature that is very different from the drastic dropping at the melting point under static conditions.
文摘考虑门架变形、轮胎刚度阻尼以及车体惯性质量等参数的影响,搭建了基于VL motion的纵向动力学模型,结合门架液压系统模型建立基于AMESim与VL motion的联合仿真分析平台,辨识负载高位抖动/晃动工况中惯性力矩的时变特征,根据零力矩点理论(Zero Moment Point,ZMP)分析了叉车纵向堆垛的稳定条件。针对叉车纵向堆垛过程中由于液压系统冲击引起的失稳问题,设计了一种组合式液压缓冲装置。仿真结果表明,由于组合式液压缓冲装置的节流与吸能作用,减轻了负载运动状态变化所引起的液压系统冲击问题,提高了叉车纵向堆垛稳定性。
基金supported by the International Technology Cooperation Project of Guizhou Province(QianKeHeWaiGZi[2012]7052)the National Scientific Research Project for Statistics(2012LZ054)
文摘As the web-server based business is rapidly developed and popularized, how to evaluate and improve the reliability of web-servers has been extremely important. Although a large num- ber of software reliability growth models （SRGMs）, including those combined with multiple change-points （CPs）, have been available, these conventional SRGMs cannot be directly applied to web soft- ware reliability analysis because of the complex web operational profile. To characterize the web operational profile precisely, it should be realized that the workload of a web server is normally non-homogeneous and often observed with the pattern of random impulsive shocks. A web software reliability model with random im- pulsive shocks and its statistical analysis method are developed. In the proposed model, the web server workload is characterized by a geometric Brownian motion process. Based on a real data set from IIS server logs of ICRMS website （www.icrms.cn）, the proposed model is demonstrated to be powerful for estimating impulsive shocks and web software reliability.
文摘<div style="text-align:justify;"> <strong>Objective</strong>: The work aimed to describe the etiological and evolutionary aspects of cardiogenic shock in the intensive care unit of the cardiology department (USIC) of the G-spot hospital in Bamako,<span "=""> Mali. <b>Materials and Methods</b></span><span "="">: This was a descriptive cross-sectional study from January 1, 2018 to April 30, 2019 that included all patients admitted to the USIC during this period. Each patient benefited from individual data support with systematic recording of socio-demographic, clinical, complementary and therapeutic data and analyzed with the SOFTWARE SPSS 20.0 French version. <b>Results</b>: The study involved 40 patients out of 311 patients hospitalized in USIC, representing a hospital frequency of 12.86%. Males were the most affected (60%) with a sex ratio of 1.50. The modal class was 41</span> - 60 years with extremes at 18 years and 89 years. Cardiovascular risk factors were dominated by HTA (27.50%), diabetes and tobacco, each with 22.50%. The general signs were tachycardia (90%), oxygen desaturation (77.50%), impregnable blood pressure (62.50%), agitation (52.50%) and an oliguria (70%). At the electrocardiogram the rhythm was sinus (80%), it was an atrial fibrillation (15%), a ventricular tachycardia (10%) and signs of coronary ischemia (necrosis in 35% and ST over shifted in 20% of cases). At cardiac doppler ultrasound,the left ventricle was dilated (50%), the right cavities dilated (30%), segmental kinetic disorder (40%), the left ventricular systolic function (FEVG) impaired (75%) and valve disease (10%). Biology noted hyper-creatinemia (65%), hyper-glycemia (12.50%), anemia and hyponatremia with 20% frequency each. Among etiology,<span "=""> ischemic heart disease accounted for 57.50% followed by pulmonary embolism 20%, dilated valve cardiomyopathy 7.50% and chronic pulmonary heart 2.50%. The trend in the majority of cases was unfavorable with 60% of deaths. Chronic pulmonary heart and pulmonary embolism were the deadliest with a frequency of 100% and 87.50% respectively. <b>Conclusion</b>: Cardiogenic shock is an infrequent condition with a high mortality of a prognosis. Ischemic heart disease is the most common etiology of the disease</span>. </div>
文摘目的观察恢刺联合超声引导下冲击波对卒中后痉挛(post-stroke spasticity,PSS)患者肌张力和运动功能的影响。方法将96例PSS患者随机分为观察组和对照组,每组48例。对照组给予超声引导下体外冲击波(extra-corporeal shock wave therapy,ESWT)治疗,观察组在对照组基础上采用恢刺阳陵泉穴治疗。观察两组治疗前后改良Ashworth量表(modified Ashworth scale,MAS)、Wolf运动功能测试(Wolf motor function test,WMFT)、功能综合评定(functional comprehensive assessment,FCA)量表、肌电均方根值(root mean square,RMS)和积分肌电值(integrated electromyogram,iEMG)变化。结果两组治疗后肌张力评分等级分布优于治疗前(P<0.05),且观察组等级分布优于对照组(P<0.05)。治疗后,两组WMFT评分均高于治疗前(P<0.05),且观察组高于对照组(P<0.05);两组FCA日常生活功能、认知功能及总分高于治疗前(P<0.05),且观察组高于对照组(P<0.05);两组RMS、iEMG低于治疗前(P<0.05),且观察组低于对照组(P<0.05)。结论恢刺联合超声引导下冲击波治疗PSS效果显著,可有效改善肌电生理指标、肌张力及运动功能,提高日常生活能力及认知水平。
文摘A vibrational formulation, a technique, and an algorithm are proposed for assessing the resonance state of a package of rectangular plates and shells having point bonds and concentrated masses with different rheological properties of deformable elements under the influence of harmonic influences. The viscoelastic properties of elements are described using the linear Boltzmann-Volterra theory. An algebraic system of equations with complex coefficients is obtained, which is solved by the Gauss method. Various problems on steady-state forced vibrations for structurally inhomogeneous mechanical systems consisting of a package of plate and shell systems with concentrated masses and shock absorbers installed in it were solved. A number of new mechanical effects have been discovered associated with a decrease in the maximum resonance amplitudes of the mechanical system as a whole. The concept of “global resonance amplitude” is introduced to study the behavior of the resonance amplitudes of a mechanical system. An analysis of the numerical results showed that the interaction of resonant amplitudes is observed only in structurally inhomogeneous systems (in this case, with elastic and viscoelastic elements) and with a noticeable approximation of the natural frequencies.
