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Recently, low-frequency oscillation (LFO) occurs in electrified railways, which exhibits a synchronous periodic oscillation of about 2-7 Hz in the traction network and electric multiple units (EMUs). To suppress the LFO, an improved model predictive control (MPC) combining with extended state observer (ESO) is proposed. First, for the design of ESO, the changes of system parameters and the unmodeled item in vehicle mathematical model are extended to a new variable and then estimated to compensate the calculated control voltage in real time. Second, the observer stability is analyzed by obtaining the transfer function, and the appropriate gains of observer are chosen through the pole assignment technique. At last, by the combination of the predictive currents, the optimal control voltages can be obtained. The control performance among MPC, dq decoupling control, passivity-based control, and the proposed method is compared. In addition, the system robustness when system parameters change is discussed. At last, to further verify the effectiveness of the proposed method for suppressing LFO, an integrated dSPACE semi-physical experimental platform including eight simulated EMUs and an equivalent traction network is constructed. Simulation and experimental results show that the proposed method not only effectively suppresses LFO but also accelerates the response speed of traction line-side converter, reduces the distortion of grid-side and vehicle-side currents, and overcomes the disadvantages of MPC and dq decoupling control under the mismatching of system parameters.
Abstract An n-Lie algebra is said to be metric if it is endowed with an invariant, non-degenerate, symmetric bilinear form. We prove that any simple n-Lie algebra over an algebraically closed field of characteristic zero admits a unique metric structure and vice versa. Further, we present two metric n-Lie algebras, which are indecomposable but admit many more metric structures. Key Words: Invariant scalar product n-Lie algebraMetric n-Lie algebra2000 Mathematics Subject Classification: 17A4217B2017B81 ACKNOWLEDGMENT The authors wish to thank the referee for constructive comments which improved the exposition and readability of this article. This work is supported by the NSF (A2007000138) of Hebei Province. Notes Communicated by A. Eldugue.
The aim of the study was to investigate the efficacy and safety of minimally invasive segmentectomy in the treatment of lung cancer. A total of 86 lung cancer patients in early stage were selected for the treatment between May, 2010 and December, 2010. The patients were randomly divided into the control (n=43) and observation (n=43) groups. Patients in the control group received conventional thoracotomy as treatment, while thoracoscopic segmentectomy was performed for patients in the observation group. Factors including intraoperative bleeding amount, number of dissected lymph nodes, surgery duration, postoperative intubation time and length of stay (LOS) were compared between the two groups. A visual analogue scale was used for comparison of the postoperative incisional pain experienced by patients in the two groups. The incidence rate of postoperative complications of patients in the two groups was observed. We also assayed variations in the levels of serum inflammatory factors C-reaction protein (CRP), interleukin (IL) -6 and -10 of patients prior to operation and on the 3rd, 5th and 7th days and after operation via ELISA, and on the 7th day after operation, we determined the pulmonary function of patients. During the 5-year follow-up, the recurrence and survival rate of patients in the two groups were observed. In the observation group, the intraoperative bleeding amount of patients was significantly lower than that in the control group, and the surgery duration, postoperative intubation time and LOS were all shorter than those in the control group (P<0.05). By contrast, no significant difference was detected in a comparison of the number of dissected lymph nodes of patients between the two groups (P>0.05). Additionally, in the observation group, patients suffered less pain after operation than those in the control group (P<0.05), and on the 3rd, 5th and 7th days after operation, the levels of CRP, IL-6 and -10 in the observation group were significantly lower than those in the control group (P<0.05). After operation, the incidence rate of complications in the observation group was significantly lower than that in the control group (P<0.05), and the recovery in pulmonary function after operation was superior to that in the control group (P<0.05). In addition, the 5-year survival rate of patients in the observation group was significantly higher than that in the control group, and the recurrence rate was significantly lower than that in the control group (P<0.05). Minimally invasive segmentectomy shows better efficacy in the treatment of lung cancer at early stage than the conventional thoracotomy. In addition to the high safety during surgery, this technique can lower the incidence rate of postoperative complications, protect the pulmonary function, increase the survival rate and decrease the recurrence rate, which shows great value in clinical practice.
To explore the mechanism for changes in brain microstructure in long-term abstinent from methamphetamine-dependence by using the diffusion tensor imaging (DTI). Methods: A total of 26 patients with long-term abstinent methamphetamine-dependence, whose abstinence time more than 14 months, and 26 normal controls all underwent cognitive executive function tests and DTI scans. We used voxel-based analysis to compare the fractional anisotropy (FA) and mean diffusivity (MD) to obtain the abnormal brain regions of DTI parameters between the two groups. Spearman correlation analysis was used to explore the correlation between FA, MD of the brain regions with abnormal parameters and cognitive executive function tests. Results: There were no statistical differences in the cognitive executive function tests between the two groups (P>0.05). Compared with the normal control group, the long-term abstinent from methamphetamine-dependence group showed the decreased FA in the right precuneus, right superior frontal gyrus, right calcarine, left inferior temporal gyrus and the increased MD in the right triangular part of inferior frontal gyrus, right precuneus, right posterior cingulate, right middle temporal gyrus, bilateral middle occipital gyrus, left superior parietal lobule, and lobule VIII of cerebellar hemisphere. The MD values of the right middle temporal gyrus in the long-term abstinent group were negatively correlated with the number of completions within 60 seconds (r=-0.504) and within 120 seconds (r=-0.464) . Conclusion: The DTI parameters in multiple brain regions from the methamphetamine-dependence patients are still abnormal after a long-term abstinence. DTI can provide imaging evidence for brain microstructural abnormalities in long-term abstinent from methamphetamine-dependence.目的：探究长期戒断甲基苯丙胺依赖者大脑微观结构的影像改变机制。方法：对26例长期戒断依赖者(戒断时间长于14个月)和26例对照组进行认知执行功能测试和扩散张量成像(diffusion-tensor imaging，DTI)检查，利用基于体素的分析方法对两组的部分各向异性(fractional anisotropy，FA)和平均扩散率(mean diffusivity， MD)进行比较，获得组间参数差异脑区，将长期戒断甲基苯丙胺组异常脑区参数值与测试结果行Spearman相关分析。结果：长期戒断甲基苯丙胺组和对照组的认知执行功能测试结果差异无统计学意义(P>0.05)；相比对照组，长期戒断甲基苯丙胺依赖组右侧楔前叶、背外侧额上回、距状裂周围皮质及左侧颞下回FA降低；右侧三角部额下回、楔前叶、后扣带回、颞中回、双侧枕中回、左侧顶上回及小脑半球8区MD升高。长期戒断甲基苯丙胺组右侧颞中回MD与数字符号60 s(r=–0.504)和120 s(r=–0.464)内完成个数均呈负相关。结论：甲基苯丙胺依赖者经长期戒断后多个脑区微结构仍存在异常，DTI可为长期戒断甲基苯丙胺依赖者脑微观结构异常提供影像学证据。.
Abstract How to reach a creative agreement in negotiations when the Zone of Possible Agreement (ZOPA) does not apparently exist? To answer this question, we drew on the cognitive flexibility theory and proposed a model predicting that negotiators’ mental fatigue would engender fewer creative agreements, and their integrative complexity acted as an underlying mechanism. Across four studies, we measured (Study 1) and manipulated (Studies 2–4) mental fatigue to test our hypotheses. We found that negotiation dyads with higher mental fatigue were less likely to display integrative complexity and hence less likely to reach creative agreements in negotiations without an apparent ZOPA. We also demonstrated that in this kind of negotiation, simply identifying additional issues or proposing packaging offers were not enough; negotiators need to do both to construct creative agreements. This research contributes to the literature of negotiation, creative problem‐solving, and the cognitive flexibility theory.
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