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Disturbance torque directly affects the tracking and measuring accuracies of seeker and the guidance precision. To analyze the degradation of gyro-stabilized seeker tracking accuracy due to disturbance torque, the dynamics models of seeker, seeker gimbal friction and seeker cable disturbance torques are established. To reduce the influence of disturbance torque on seeker tracking accuracy, a practical disturbance observer (DOB) is designed to compensate the disturbance torques. Multi-rate sampling problem due to the difference between sampling and hold times of seeker system and DOB is considered. A discrete DOB design method is proposed based on Nyquist stability theory, so the conservation of small gain design method can be removed. Sampling, hold and filter time constants of DOB are specified by balancing system stability, disturbance torque compensation and sensor noise reduction. An extracting method of information which is required by DOB is proposed by integrating the measurement information of missile and seeker. The mathematical simulation results show that the designed DOB can improve the seeker tracking accuracy efficiently. [ABSTRACT FROM AUTHOR]

Objective: To explore the clinical effects of posterior short-segment pedicle screw internal fixation combined with vertebroplasty for the treatment of Kümmell disease with kyphosis., Methods: Twenty-four patients with Kümmell disease complicated with kyphosis treated by posterior short-segment pedicle screw internal fixation combined with vertebroplasty from January 2016 to December 2018 were retrospectively analyzed, including 6 males and 18 females, aged 63 to 85 (73.1±6.5) years old. The clinical effect was evaluate by visual analogue scale (VAS), Oswestry Disability Index (ODI), the anterior height of injured vertebral body, and the sagittal Cobb angle of the affected segment beforeoperation, at 3 days and final follow up after operation. And the surgical complications were observed., Results: All 24 patients were followed up from 12 to 24 months with an average of (15.5±3.2) months. The VAS score was decreased from 5.21±1.06 preoperatively to 2.38±0.58 at 3 days postoperatively and 1.71±0.75 at final follow-up;ODI was decreased from (50.4±13.5)% preoperatively to (20.9±8.0)% at 3 days postoperatively and (16.7±9.6)% at final follow-up;the anterior height of injured vertebral body was restored from (8.0±4.2) mm before surgery to (18.1±5.0) mm at 3 days after surgery and (16.8±5.1) mm at final follow up;the sagittal Cobb angle of affected segment was decreased from (19.5±6.3)° preoperatively to (7.6±2.1)° at 3 days after surgery and(8.4±1.7)° at final follow-up. VAS, ODI, anterior height of injured vertebral body, and sagittal Cobb angle of affected segment were significantly improved at 3 days after operation and at final follow-up ( P <0.05). Two patients had complications, including asymptomaticcement leakage in 1 patient and superficial wound infection in 1 patient., Conclusion: Posterior short-segment pedicle screw internal fixation combined with vertebroplasty for the treatment of Kümmell disease with kyphosis has relatively small surgical trauma, excellent clinical results, good vertebral height recovery, satisfactory correction of kyphotic angle, and fewer complications, etc. It is a safe and effective surgical method to treat Kümmell disease with kyphosis.

In order to explore the correlation between the medicinal properties，efficacy and application in the same genetic relationship，explain the scientific connotation of the medicinal properties and effects of traditional Chinese medicines(TCM)，promote the academic development of the theory of traditional Chinese medicines，and provide reference for the research and development of the traditional Chinese medicines of a same genus. In this paper, a literature study of ancient and modern works of Chinese herbal medicine was conducted to investigate the correlation between the properties, meridians tropism, efficacy and application of Alpinia officinarum， A. katsumadai， Galangae Fructus and Alpinae Oxyphyllae Fructus, four kinds of Alpinia Chinese medicines．The results showed that the similar properties of these four kinds of Alpinia Chinese medicines included that they were acrid, warm,and mainly getting into the spleen and stomach channels; the similar efficacies included that dispelling cold，relieving pain，warming stomach，anti-nausea，anti-diarrheal，reinforcing spleen to promote digestion and other effects; in application aspects, the similarities were that they were all mainly used in treatment of catching cold or spleen deficiency induced by abdominal pain，vomiting，diarrhea,diet indigestion, etc. indicating that phylogenetic relationship was closely related with the herbal properties, efficacy and application. It is an effective way to explore，collate and research traditional Chinese medicine by using plant phylogenetic relationships in exploring the internal relations and laws of TCM theories，material bases, pharmacological effects and clinical applications, also with a strong maneuverability to explain their scientific connotation., Competing Interests: The authors of this article and the planning committee members and staff have no relevant financial relationships with commercial interests to disclose., (Copyright© by the Chinese Pharmaceutical Association.)

Objective: To evaluate the effectiveness of locking plate external fixator in treating middle and distal tibial fractures., Methods: From January 2010 to January 2013,18 patients suffered from middle and distal tibial fractures were treated by locking plate external fixator,including 11 males and 7 females, with an average age of 53.5 (ranged from 13 to 80) years old,the course of disease ranged from 2 h to 3 d. According to AO classification, 4 cases were type A,11 cases were type B and 3 were type C. Among them,6 patients were open fracture, including 2 cases with type I, 3 cases with type II and 1 case with type III, according to Gustilo classification), 12 patients were close fracture. Operation time, postoperative complications were observed, and Johner-Wruhs scoring were used to evaluate clinical outcomes., Results: All patients were followed up from 6 to 15 (meaned 11) months. Two cases occurred skin necrosis (1 case occurred bone exposure), 2 cases occurred delayed union (all were open fracture), and 1 case occurred nail infection. No screw loosening or broken occurred. According to Johner-Wruhs scoring, 10 cases obtained excellent result,6 cases good,and 2 cases fine., Conclusion: Locking plate external fixator for the treatment of middle and distal tibial fractures, which has advantages of lessen damage, shorter operative time, less complications and rapid functional recovery, is one of good choice.

Based on the remote sensing images and the meteorological data in 1986 and 2000, and by using the model of extracting vegetation coverage, the spatiotemporal changes of vegetation coverage in the farming-pastoral ecotone of Northern China in 1986-2000 were studied, with the effects of climate and land use change on the changes analyzed. The results showed that in this ecotone, the area with lower vegetation coverage was increasing, while that with higher vegetation coverage was in adverse. The regions with increasing vegetation coverage were mainly in the east of northeast section, the west of north section, and the west of northwest section of the ecotone, while the vegetation coverage in the other sections was obviously degraded. The vegetation coverage were positively correlated with precipitation and aridity index, but negatively correlated with temperature. The change direction and extent of the vegetation coverage varied with land use types.