We experimentally discussed the output characteristics of a passively mode-locked erbium-doped fiber laser using a single-mode fiber(SMF)structure as a saturable absorber(SA)based on nonlinear optic loop mirror(NOLM)....We experimentally discussed the output characteristics of a passively mode-locked erbium-doped fiber laser using a single-mode fiber(SMF)structure as a saturable absorber(SA)based on nonlinear optic loop mirror(NOLM).The NOLM acting as an SA has properties of controllable pulse interval and pulse width.Four different types of NOLMs are experimentally discussed and the results show that fine adjustment to the coupler ratio together with optimization of the SMF length inside the NOLM can simultaneously implement high pulse energy and pulse internal tunability.The laser configuration provides a method to generate well-performing mode-locked lasing,and the investigations of the effects of changing some parameters of the laser also provide some help for the development of mode-locked fiber laser based on NOLM.展开更多
BACKGROUND Despite the potential benefits of fecal diversion after low pelvic anastomosis in colorectal surgery, diverting loop ileostomy construction is related to significant rates of complications. AIM To determine...BACKGROUND Despite the potential benefits of fecal diversion after low pelvic anastomosis in colorectal surgery, diverting loop ileostomy construction is related to significant rates of complications. AIM To determine potential predictors of high output related complications in patients with diverting loop ileostomy creation after colorectal surgery. METHODS Patients who underwent open and laparoscopic colorectal surgery requiring a diverting loop ileostomy from January 2010 to March 2018 were retrospectively analyzed. We included patients older than 18 years, who underwent colorectal surgery with primary low pelvic anastomosis, and with the creation of a diverting loop ileostomy, at elective or emergency settings for the treatment of benign or malignant conditions. Univariate and multivariate logistic regression analysis was used to determine the effect of the potential predictors on the rate of high output related complications. The high output related complications were dehydration and acute renal failure that required visits to the emergency department and hospitalizations. RESULTS Of the 102 patients included in the study, 23.5%(n = 24) suffered high output related complications. In this group of patients at least one visit to the emergency department (mean 1.6), and at least one readmission to the hospital was needed. The factors associated with high-output ileostomy, in the univariate analysis, were: urgent surgical intervention (OR = 2.6;P = 0.047), the development of postoperative complications (OR = 3;P = 0.024), have ulcerative colitis (OR = 4.8;P = 0.017), use of steroids (OR = 4.3;P = 0.010), mean output at discharge greater than 1000 mL/24 h (OR = 3.2;P = 0.016), and use of loperamide at discharge (OR = 2.8;P = 0.032). Multivariate logistic regression analysis identified two independent risk factors for high output related complications: ulcerative colitis [OR = 7.6 (95%CI: 1.81-31.95);P = 0.006], and ileostomy output at discharge ≥ 1000 mL/24 h [OR = 3.3 (1.18-9.37);P = 0.023]. CONCLUSION In our study, patients with ulcerative colitis and those with an ileostomy output above 1000 mL/24 h at discharge, were at increased risk of high output related complications.展开更多
The non-minimum phase feature of tail-controlled missile airframes is analyzed. Three selection strategies for desired performance indexes are presented. An acceleration autopilot design methodology based on output fe...The non-minimum phase feature of tail-controlled missile airframes is analyzed. Three selection strategies for desired performance indexes are presented. An acceleration autopilot design methodology based on output feedback and optimization is proposed. Performance and robustness comparisons between the two-loop and classical three-loop topologies are made. Attempts to improve the classical three-loop topology are discussed. Despite the same open-loop structure, the classical three-loop autopilot shows distinct characteristics from a two-loop autopilot with PI compensator. Both the two-loop and three-loop topologies can stabilize a static unstable missile. However, the finite actuator resource is the crucial factor dominating autopilot function.展开更多
In this paper, the nonlinear control of chaotic oscillations was investigated by using the input output linearization control method. The chaotic attitude of a kind of spacecraft was discussed. It is demonstrated that...In this paper, the nonlinear control of chaotic oscillations was investigated by using the input output linearization control method. The chaotic attitude of a kind of spacecraft was discussed. It is demonstrated that the input output linearization control law is the nonlinear version of the parametric open plus closed loop control law.展开更多
Curcumin has been shown to significantly improve spatial memory impairment induced by HIV-1 gp 120 V3 in rats, but the electrophysiological mechanism remains unknown. Using extracellular microelectrode recording techn...Curcumin has been shown to significantly improve spatial memory impairment induced by HIV-1 gp 120 V3 in rats, but the electrophysiological mechanism remains unknown. Using extracellular microelectrode recording techniques, this study confirmed that the gp120 V3 loop could suppress long-term potentiation in the rat hippocampal CA1 region and synaptic plasticity, and that curcumin could antagonize these inhibitory effects. Using a Fura-2/AM calcium ion probe, we found that curcumin resisted the effects of the gp120 V3 loop on hippocampal synaptosomes and decreased Ca2＋ concentration in synaptosomes. This effect of curcumin was identical to nimodipine, suggesting that curcumin improved the inhibitory effects of gpl20 on synaptic plasticity, ameliorated damage caused to the central nervous system, and might be a potential neuroprotective drug.展开更多
调配缓冲槽作为核燃料含铀含硝酸废液回收处理的重要设备,其液位控制稳定性直接影响整个含铀含硝酸废液处理系统的安全稳定运行。若缓冲槽液位控制稳定性差,可能会导致含放射性与有毒物质的核燃料废液溢流、上游工艺系统非计划停车等安...调配缓冲槽作为核燃料含铀含硝酸废液回收处理的重要设备,其液位控制稳定性直接影响整个含铀含硝酸废液处理系统的安全稳定运行。若缓冲槽液位控制稳定性差,可能会导致含放射性与有毒物质的核燃料废液溢流、上游工艺系统非计划停车等安全生产事故,不仅造成控制系统无法连续稳定运行,还会影响下游蒸发浓缩系统、膜过滤系统的运行状态及处理效率。针对含铀含硝酸废液处理系统中缓冲槽液位控制稳定性差的问题,本文提出一种基于模型辨识的多输入单输出液位控制系统方法。首先,利用现场调试数据,采用模型辨识方法建立多输入单输出缓冲槽液位控制系统数学模型。其次,在已建模型基础上改进相关控制方式,提出三回路串级控制方式,经仿真验证得到了一种自适应规则整定比例-积分-微分(Proportional-Integral-Derivative,PID)参数。最后,在工程实际中通过集散控制系统(Distributed Control System,DCS)组态和控制器自适应整定规则的写入,对所提的方法进行了验证。结果表明,该方法具备较强自适应能力,可有效提升系统的稳定性,缩短调节时间,成功解决调配缓冲槽液位控制效果不佳的问题,保证整个工艺生产平稳运行。展开更多
输入串联输出串联(input-series and output-series,ISOS)逆变器系统的控制目标是在实现输入均压的同时,控制输出电压的幅值和相位都相等从而实现输出均压。在已有的输入均压结合输出同角度的三环控制策略的基础上,对系统的控制环,即输...输入串联输出串联(input-series and output-series,ISOS)逆变器系统的控制目标是在实现输入均压的同时,控制输出电压的幅值和相位都相等从而实现输出均压。在已有的输入均压结合输出同角度的三环控制策略的基础上,对系统的控制环,即输入均压环和输出电压环之间的解耦关系进行分析,并在此基础上分别对它们进行具体的参数设计,以使系统具有良好的稳态和动态性能。仿真及实验结果验证了环路间的解耦关系及参数设计的合理性与有效性。展开更多
兼顾二次谐波电流抑制和动态性能改善是两级式逆变器中前级直流变换器的基本控制目标。该文从阻抗的观点出发,指出使前级直流变换器的闭环输出阻抗在二倍输出电压频率处呈现高阻抗,而在非二倍输出电压频率处呈现低阻抗是实现此控制目标...兼顾二次谐波电流抑制和动态性能改善是两级式逆变器中前级直流变换器的基本控制目标。该文从阻抗的观点出发,指出使前级直流变换器的闭环输出阻抗在二倍输出电压频率处呈现高阻抗,而在非二倍输出电压频率处呈现低阻抗是实现此控制目标的基本方法。采用与前级直流变换器的输出阻抗串联虚拟阻抗,并同时与中间母线电容并联虚拟阻抗的方法,实现了所提出的基本方法,并以Buck类的前级直流变换器为例,给出实现虚拟串联阻抗和虚拟并联阻抗的控制框图。通过对该控制框图进行等效变换,可推导得到现有文献中已提出的二次谐波电流抑制方法。最后,研制一台1 k VA原理样机,并通过理论分析和实验验证对这些不同控制方法的二次谐波电流抑制效果及对系统动态性能的改善作用进行对比。实验结果证明了理论分析的正确性。展开更多
基金supported in part by the Zhejiang Province Science and Technology Plan Projects(No.LGG19F050001)the National Natural Science Foundation of China(No.601705055)the Zhejiang Provincial Natural Science Foundation of China(No.LY17F050012)。
文摘We experimentally discussed the output characteristics of a passively mode-locked erbium-doped fiber laser using a single-mode fiber(SMF)structure as a saturable absorber(SA)based on nonlinear optic loop mirror(NOLM).The NOLM acting as an SA has properties of controllable pulse interval and pulse width.Four different types of NOLMs are experimentally discussed and the results show that fine adjustment to the coupler ratio together with optimization of the SMF length inside the NOLM can simultaneously implement high pulse energy and pulse internal tunability.The laser configuration provides a method to generate well-performing mode-locked lasing,and the investigations of the effects of changing some parameters of the laser also provide some help for the development of mode-locked fiber laser based on NOLM.
文摘BACKGROUND Despite the potential benefits of fecal diversion after low pelvic anastomosis in colorectal surgery, diverting loop ileostomy construction is related to significant rates of complications. AIM To determine potential predictors of high output related complications in patients with diverting loop ileostomy creation after colorectal surgery. METHODS Patients who underwent open and laparoscopic colorectal surgery requiring a diverting loop ileostomy from January 2010 to March 2018 were retrospectively analyzed. We included patients older than 18 years, who underwent colorectal surgery with primary low pelvic anastomosis, and with the creation of a diverting loop ileostomy, at elective or emergency settings for the treatment of benign or malignant conditions. Univariate and multivariate logistic regression analysis was used to determine the effect of the potential predictors on the rate of high output related complications. The high output related complications were dehydration and acute renal failure that required visits to the emergency department and hospitalizations. RESULTS Of the 102 patients included in the study, 23.5%(n = 24) suffered high output related complications. In this group of patients at least one visit to the emergency department (mean 1.6), and at least one readmission to the hospital was needed. The factors associated with high-output ileostomy, in the univariate analysis, were: urgent surgical intervention (OR = 2.6;P = 0.047), the development of postoperative complications (OR = 3;P = 0.024), have ulcerative colitis (OR = 4.8;P = 0.017), use of steroids (OR = 4.3;P = 0.010), mean output at discharge greater than 1000 mL/24 h (OR = 3.2;P = 0.016), and use of loperamide at discharge (OR = 2.8;P = 0.032). Multivariate logistic regression analysis identified two independent risk factors for high output related complications: ulcerative colitis [OR = 7.6 (95%CI: 1.81-31.95);P = 0.006], and ileostomy output at discharge ≥ 1000 mL/24 h [OR = 3.3 (1.18-9.37);P = 0.023]. CONCLUSION In our study, patients with ulcerative colitis and those with an ileostomy output above 1000 mL/24 h at discharge, were at increased risk of high output related complications.
文摘The non-minimum phase feature of tail-controlled missile airframes is analyzed. Three selection strategies for desired performance indexes are presented. An acceleration autopilot design methodology based on output feedback and optimization is proposed. Performance and robustness comparisons between the two-loop and classical three-loop topologies are made. Attempts to improve the classical three-loop topology are discussed. Despite the same open-loop structure, the classical three-loop autopilot shows distinct characteristics from a two-loop autopilot with PI compensator. Both the two-loop and three-loop topologies can stabilize a static unstable missile. However, the finite actuator resource is the crucial factor dominating autopilot function.
基金Supported by the National Natural Science Foundation of China!( 19782 0 0 3 ) theChina Postdoctoral Science Foundation and
文摘In this paper, the nonlinear control of chaotic oscillations was investigated by using the input output linearization control method. The chaotic attitude of a kind of spacecraft was discussed. It is demonstrated that the input output linearization control law is the nonlinear version of the parametric open plus closed loop control law.
基金supported by the National Natural Science Foundation of China,No.81171134 and 81471235a grant from the Introducing Talents of Discipline to Universities,No.B14036+4 种基金a grant from the College Students’Extracurricular Scientific Innovation and Entrepreneurial Activity Research Topic of Jinan University Challenge Cup,No.(2013)27 and (2014)16a grant from the College Students’Extracurricular Scientific Innovation and Entrepreneurial Activity Research Topic of Jinan University in China,No.201410559079,1055914162 and CX14261a grant from the National Basic Research Program of China(973 Program),No.2011CB707501the Science and Technology Foundation of Guangdong Province in China,No.2010B030700016the Natural Science Foundation of Guangdong Province in China,No.2014A030313360
文摘Curcumin has been shown to significantly improve spatial memory impairment induced by HIV-1 gp 120 V3 in rats, but the electrophysiological mechanism remains unknown. Using extracellular microelectrode recording techniques, this study confirmed that the gp120 V3 loop could suppress long-term potentiation in the rat hippocampal CA1 region and synaptic plasticity, and that curcumin could antagonize these inhibitory effects. Using a Fura-2/AM calcium ion probe, we found that curcumin resisted the effects of the gp120 V3 loop on hippocampal synaptosomes and decreased Ca2＋ concentration in synaptosomes. This effect of curcumin was identical to nimodipine, suggesting that curcumin improved the inhibitory effects of gpl20 on synaptic plasticity, ameliorated damage caused to the central nervous system, and might be a potential neuroprotective drug.
文摘调配缓冲槽作为核燃料含铀含硝酸废液回收处理的重要设备,其液位控制稳定性直接影响整个含铀含硝酸废液处理系统的安全稳定运行。若缓冲槽液位控制稳定性差,可能会导致含放射性与有毒物质的核燃料废液溢流、上游工艺系统非计划停车等安全生产事故,不仅造成控制系统无法连续稳定运行,还会影响下游蒸发浓缩系统、膜过滤系统的运行状态及处理效率。针对含铀含硝酸废液处理系统中缓冲槽液位控制稳定性差的问题,本文提出一种基于模型辨识的多输入单输出液位控制系统方法。首先,利用现场调试数据,采用模型辨识方法建立多输入单输出缓冲槽液位控制系统数学模型。其次,在已建模型基础上改进相关控制方式,提出三回路串级控制方式,经仿真验证得到了一种自适应规则整定比例-积分-微分(Proportional-Integral-Derivative,PID)参数。最后,在工程实际中通过集散控制系统(Distributed Control System,DCS)组态和控制器自适应整定规则的写入,对所提的方法进行了验证。结果表明,该方法具备较强自适应能力,可有效提升系统的稳定性,缩短调节时间,成功解决调配缓冲槽液位控制效果不佳的问题,保证整个工艺生产平稳运行。
文摘输入串联输出串联(input-series and output-series,ISOS)逆变器系统的控制目标是在实现输入均压的同时,控制输出电压的幅值和相位都相等从而实现输出均压。在已有的输入均压结合输出同角度的三环控制策略的基础上,对系统的控制环,即输入均压环和输出电压环之间的解耦关系进行分析,并在此基础上分别对它们进行具体的参数设计,以使系统具有良好的稳态和动态性能。仿真及实验结果验证了环路间的解耦关系及参数设计的合理性与有效性。
文摘兼顾二次谐波电流抑制和动态性能改善是两级式逆变器中前级直流变换器的基本控制目标。该文从阻抗的观点出发,指出使前级直流变换器的闭环输出阻抗在二倍输出电压频率处呈现高阻抗,而在非二倍输出电压频率处呈现低阻抗是实现此控制目标的基本方法。采用与前级直流变换器的输出阻抗串联虚拟阻抗,并同时与中间母线电容并联虚拟阻抗的方法,实现了所提出的基本方法,并以Buck类的前级直流变换器为例,给出实现虚拟串联阻抗和虚拟并联阻抗的控制框图。通过对该控制框图进行等效变换,可推导得到现有文献中已提出的二次谐波电流抑制方法。最后,研制一台1 k VA原理样机,并通过理论分析和实验验证对这些不同控制方法的二次谐波电流抑制效果及对系统动态性能的改善作用进行对比。实验结果证明了理论分析的正确性。
