目的通过临床随访和影像学分析研究腰椎棘突间动态固定对相邻节段退变的影响。方法：2007年9月．2009年9月应用后路减压结合腰椎棘突间动态固定治疗14／5单节段退变性疾患病例76例，其中应用静态Wallis固定系统45例，动态Coflex固定系...目的通过临床随访和影像学分析研究腰椎棘突间动态固定对相邻节段退变的影响。方法：2007年9月．2009年9月应用后路减压结合腰椎棘突间动态固定治疗14／5单节段退变性疾患病例76例，其中应用静态Wallis固定系统45例，动态Coflex固定系统3l例。主要适应证包括腰椎间盘突出症和轻度腰椎管狭窄症。采用腰痛VAS评分、下肢痛VAS评分、腰椎JOA评分（29分法）评定临床症状情况，采用Prolo腰椎功能评定标准和ODI评分评定功能情况，术前和末次随访各评价1次；在术前和末次随访腰椎正侧位X线片上测量手术节段（L4／5）前凸角和上、下位相邻节段（L3／4和LS／S1）的前凸角以及腰椎整体前凸角（Ll-S1）；在术前和末次随访腰椎过伸过屈位X线片上测量L3／4、IA／5、LS／S1活动度及腰椎整体活动度。术前和末次随访分别对L3／4和L5，Sl进行UCLA（University of Califomia at Los Angeles）分级评定。结果：66例患者获得完整随访，Wallis组41例，Coflex组25例，随访时间57。81个月，平均64．6个月。末次随访时，两组患者的腰痛VAS评分、下肢痛VAS评分、腰椎JOA评分、Prolo腰椎功能评定标准和ODI评分较术前均有显著性改善（火0．01）；L4／5的前凸角和腰椎整体前凸角较术前均有明显下降（P〈0．01），IA／5活动度和腰椎整体活动度较术前均明显下降（P〈O．01）；L3／4和L5，s1的前凸角较术前无显著性变化（P〉O．05），L3，4的活动度较术前下降有统计学差异（P〈0．05），而L5／S1的活动度较术前无显著性变化（P〉0．05）。Wallis组末次随访时同术前相比，L3／4节段有2例由UCIJA I级变为UCLAⅡ级：L5／S1节段有4例由UCIJA I级变为UCLAⅡ级．1例由UCIJAⅡ级变为UCLAⅢ级。Coflex组末次随访时同术前相比，L3，4节段只有1例由UCIA I级变为UCIAⅡ级；L5／S1节段有2例由UCLA I级变为UCLAⅡ级，1例由UCLAⅡ级变为UCLAⅢ级。结论：后路减压结合腰椎棘突间动态固定治疗腰椎单节段退变性疾病临床效果满意，未发现症状性相邻节段退变，但其对相邻节段退变的影响有待进一步对照研究的结果和更长时间的临床随访。展开更多
A nonlinear lateral-torsional coupled vibration model of a planetary gear system was established by taking transmission errors,time varying meshing stiffness and multiple gear backlashes into account.The bifurcation d...A nonlinear lateral-torsional coupled vibration model of a planetary gear system was established by taking transmission errors,time varying meshing stiffness and multiple gear backlashes into account.The bifurcation diagram of the system's motion state with rotational speed of sun gear was conducted through four steps.As a bifurcation parameter,the effect of rotational speed on the bifurcation properties of the system was assessed.The study results reveal that periodic motion is the main motion state of planetary gear train in low speed region when ns<2 350 r/min,but chaos motion state is dominant in high speed region when ns>2 350 r/min,The way of periodic motion to chaos is doubling bifurcation.There are two kinds of unstable modes and nine unstable regions in the speed region when 1 000 r/min<ns<3 000 r/min.展开更多
Error codes induced by M-ary modulation and modulation selection in network-based control systems are studied.It is the first time the issue of error codes induced by M-ary modulation is addressed in control field.In ...Error codes induced by M-ary modulation and modulation selection in network-based control systems are studied.It is the first time the issue of error codes induced by M-ary modulation is addressed in control field.In network-based control systems,error codes induced by noisy channel can significantly decrease the quality of control.To solve this problem,the network-based control system with delay and noisy channel is firstly modeled as an asynchronous dynamic system(ADS).Secondly,conditions of packet with error codes(PEC)loss rate by using M-ary modulation are obtained based on dynamic output feedback scheme.Thirdly,more importantly,the selection principle of M-ary modulation is proposed according to the measured signal-to-noise ratio(SNR)and conditions of PEC loss rate.Finally,system stability is analyzed and controller is designed through Lyapunov function and linear matrix inequality(LMI)scheme,and numerical simulations are made to demonstrate the effectiveness of the proposed scheme.展开更多
文摘目的通过临床随访和影像学分析研究腰椎棘突间动态固定对相邻节段退变的影响。方法：2007年9月．2009年9月应用后路减压结合腰椎棘突间动态固定治疗14／5单节段退变性疾患病例76例，其中应用静态Wallis固定系统45例，动态Coflex固定系统3l例。主要适应证包括腰椎间盘突出症和轻度腰椎管狭窄症。采用腰痛VAS评分、下肢痛VAS评分、腰椎JOA评分（29分法）评定临床症状情况，采用Prolo腰椎功能评定标准和ODI评分评定功能情况，术前和末次随访各评价1次；在术前和末次随访腰椎正侧位X线片上测量手术节段（L4／5）前凸角和上、下位相邻节段（L3／4和LS／S1）的前凸角以及腰椎整体前凸角（Ll-S1）；在术前和末次随访腰椎过伸过屈位X线片上测量L3／4、IA／5、LS／S1活动度及腰椎整体活动度。术前和末次随访分别对L3／4和L5，Sl进行UCLA（University of Califomia at Los Angeles）分级评定。结果：66例患者获得完整随访，Wallis组41例，Coflex组25例，随访时间57。81个月，平均64．6个月。末次随访时，两组患者的腰痛VAS评分、下肢痛VAS评分、腰椎JOA评分、Prolo腰椎功能评定标准和ODI评分较术前均有显著性改善（火0．01）；L4／5的前凸角和腰椎整体前凸角较术前均有明显下降（P〈0．01），IA／5活动度和腰椎整体活动度较术前均明显下降（P〈O．01）；L3／4和L5，s1的前凸角较术前无显著性变化（P〉O．05），L3，4的活动度较术前下降有统计学差异（P〈0．05），而L5／S1的活动度较术前无显著性变化（P〉0．05）。Wallis组末次随访时同术前相比，L3／4节段有2例由UCIJA I级变为UCLAⅡ级：L5／S1节段有4例由UCIJA I级变为UCLAⅡ级．1例由UCIJAⅡ级变为UCLAⅢ级。Coflex组末次随访时同术前相比，L3，4节段只有1例由UCIA I级变为UCIAⅡ级；L5／S1节段有2例由UCLA I级变为UCLAⅡ级，1例由UCLAⅡ级变为UCLAⅢ级。结论：后路减压结合腰椎棘突间动态固定治疗腰椎单节段退变性疾病临床效果满意，未发现症状性相邻节段退变，但其对相邻节段退变的影响有待进一步对照研究的结果和更长时间的临床随访。
基金Project(50775108) supported by the National Natural Science Foundation of China
文摘A nonlinear lateral-torsional coupled vibration model of a planetary gear system was established by taking transmission errors,time varying meshing stiffness and multiple gear backlashes into account.The bifurcation diagram of the system's motion state with rotational speed of sun gear was conducted through four steps.As a bifurcation parameter,the effect of rotational speed on the bifurcation properties of the system was assessed.The study results reveal that periodic motion is the main motion state of planetary gear train in low speed region when ns<2 350 r/min,but chaos motion state is dominant in high speed region when ns>2 350 r/min,The way of periodic motion to chaos is doubling bifurcation.There are two kinds of unstable modes and nine unstable regions in the speed region when 1 000 r/min<ns<3 000 r/min.
基金Project(61172022) supported by the National Natural Science Foundation of ChinaProject(GDW20151100010) supported by the State Administration of Foreign Experts Affairs of China
文摘Error codes induced by M-ary modulation and modulation selection in network-based control systems are studied.It is the first time the issue of error codes induced by M-ary modulation is addressed in control field.In network-based control systems,error codes induced by noisy channel can significantly decrease the quality of control.To solve this problem,the network-based control system with delay and noisy channel is firstly modeled as an asynchronous dynamic system(ADS).Secondly,conditions of packet with error codes(PEC)loss rate by using M-ary modulation are obtained based on dynamic output feedback scheme.Thirdly,more importantly,the selection principle of M-ary modulation is proposed according to the measured signal-to-noise ratio(SNR)and conditions of PEC loss rate.Finally,system stability is analyzed and controller is designed through Lyapunov function and linear matrix inequality(LMI)scheme,and numerical simulations are made to demonstrate the effectiveness of the proposed scheme.
