Four-quadrant Force Control with Minimal Ripple for Linear Switched Reluctance Machines

Linear switch reluctance machine(LSRM)has been tried to act as an alternative generator for direct drive linear wave energy converter(WEC).Many researchers have proposed new topologies of LSRM to improve the power density,efficiency and reliability.However,the control methods for LSRM applied in direct drive WEC have been paid little attention,especially control methods considering the wave energy generator operating characteristics.In this paper,according to the generator control requirements of the direct drive WEC,force control algorithm for LSRM operating in four quadrants without a speed closed loop is put forward.The force ripple of LSRM is suppressed using force sharing function method.The four-quadrant control is easy to realize requiring only phase currents information.Simulation results validate the proposed method and indicate that LSRM is able to be used as the generator for direct drive WEC.

Evaluating students' learning situations using “Four-quadrant law”

Evaluation is widely acknowledged as a powerful means of improving the quality of education and it is a very important component of the education system. However, the current mainstream evaluation method is based on the examination as the common way, which has very limited help to instructors' teaching. In this paper, based on an online learning platform named "educoder", we design an evaluation method by using "Four-quadrant law", which divides students' learning situations into four types. In addition, we provide some suggestions for instructors about how to give targeted teaching to different students in each type. We verify that our method is useful by setting up experiments. The experiment results show that our method can effectively improve the quality of instructors' teaching.

单钢板治疗胫骨平台双髁骨折并发症报告

目的报告单块外侧支撑钢板治疗胫骨平台双髁骨折的相关并发症、感染率及功能评估。方法回顾自1996年3月～2003年7月收治的78例胫骨平台双髁骨折(男性50例,女性28例;年龄24～69岁,平均41岁),并进行功能评估和手术并发症统计分析,以P<0.05为显著性差异。结果Rasmussen功能评定优良率为74.4%。7例发生深部感染,深部感染的发生与关节功能不佳密切相关(P<0.05)。患者的年龄、性别、是否为开放性骨折、是否为延期或急诊手术、手术历时、术中出血量均未显现出与深部感染发生的相关联性,而植入异体骨成为本组资料中唯一与深部感染发生相关联的指标(P<0.05)。结论单块外侧支撑钢板治疗胫骨平台双髁骨折有较低的深部感染率,而异体骨植入可能增加深部感染的发生。正确的软组织条件判断和处理有助于降低切口相关并发症。

3.5和4.5mm钢板固定治疗胫骨平台双髁骨折的生物力学比较研究

目的评价3.5和4.5 mm钢板固定治疗胫骨平台双髁骨折的生物力学差异。方法将24个复合人工骨模型分为胫骨平台内、外髁骨折(SchatzkerⅤ型)组和胫骨平台髁骨折伴干骺端分离骨折(SchatzkerⅥ型)组,每组12个。每组6个模型采用3.5 mm胫骨近端锁定钢板固定,6个用4.5mm胫骨近端锁定钢板固定。测试方法包括施加500 N垂直载荷、荷载循环10 000次及固定失效时荷载。结果 SchatzkerⅤ型模型10、100、1 000和10 000次荷载循环后,钢板向下位移和塑性变形比较差异无统计学意义。4.5 mm钢板固定失效时荷载更高(P=0.05)。SchatzkerⅥ型模型10、100、1 000和10 000次荷载循环后,钢板向下位移和弹性变形比较差异有统计学意义。4.5 mm钢板固定失效时轴向荷载更高,但差异无统计学意义(P=0.214)。结论 3.5和4.5 mm固定钢板在循环载荷、弹性和塑性变形方面比较,差异无统计学意义。但3.5 mm钢板尺寸小、耗损低,从生物力学角度考虑是胫骨平台双踝骨折重建的较好选择。

漂浮体位下后内侧联合前外侧入路治疗胫骨平台双髁骨折疗效分析

目的探讨漂浮体位下后内侧联合前外侧入路治疗累及后内侧髁胫骨平台双髁骨折的临床疗效。方法收集累及后内侧髁的胫骨平台双髁骨折患者54例膝关节,均为单膝损伤,其中C1型13例,C2型17例,C3型24例。手术均采用漂浮体位下通过后内侧联合前外侧入路,术中探查半月板、韧带损伤情况并予以相应的修复,骨折予以复位、植骨支撑、钢板固定,术后制定康复方案,定期随访。结果本组54例患者平均住院时间18.7±5.6 d,随访6~49个月,平均随访时间17.86±3.57月;愈合时间为7.45±1.34月。住院时间与性别和年龄均无关,但与AO分型有关;愈合时间和总有效率均与性别无关,但均与年龄和AO分型有关。术后无1例发生切口及深部感染、切口周围皮瓣坏死、关节不稳、骨筋膜室综合征和内、外翻畸形愈合等并发症。术后至取出内固定装置,无1例出现钢板螺钉松动和断裂、膝关节明显强直。根据Sanders膝关节功能评分标准,显效31例,有效17例,尚可5例,无效1例,总有效例数48例,总有效率为88.89%。结论采用漂浮体位下后内侧联合前外侧入路可有效取得骨折的复位、固定牢靠,远期疗效满意。

后内侧联合前外侧入路治疗累及后内髁的胫骨平台双髁骨折21例分析

目的探讨后内侧联合前外侧手术入路治疗后内髁受累及的胫骨平台双髁骨折的临床疗效。方法收集21例累及后内髁的SchatzkerⅤ型、Ⅵ型胫骨平台骨折患者,其中累及双后髁的5例,不累及外后髁的16例,手术均采用后内侧联合前外侧入路,手术中对于累及后外侧髁的患者,关节镜下监视行前外侧开窗,通过骨隧道复位、植骨支撑、固定。结果本组21例患者获得平均(12.24±2.48)个月的随访,骨折均获骨性愈合,愈合时间4～9月,无切口皮肤坏死、关节不稳及内外翻畸形愈合等发生。膝关节功能:优13例,良5例,可2例,差1例。骨折复位满意度:优15例,良4例,可1例,差1例。结论对于累及后内侧髁的胫骨平台双髁骨折,采用后内侧联合前外侧入路能有效取得骨折的复位、牢靠固定,并可早期进行功能训练,远期疗效满意。

双钢板结合缝合锚钉治疗胫骨平台双髁骨折

目的回顾性分析双钢板结合缝合锚钉治疗胫骨平台双髁骨折的有效性和安全性。方法选取2014年1月——2017年12月在我院创伤骨科住院治疗,诊断为Schatzker Ⅴ、Ⅵ型胫骨平台骨折44例,其中Ⅴ型30例,Ⅵ型14例,所有患者均采用双侧锁定钢板内固定,内外侧塌陷的关节面骨块使用克氏针固定支撑,并对11例较大骨缺损使用人造骨填充,交叉韧带、侧副韧带起止点撕脱骨折及撕裂均采用缝合锚钉修补重建,术后采用Rasmussen评分系统评价患者功能,并比较两种分型最终评分情况、术后植骨与不植骨外侧关节面塌陷度等。结果所有患者得到9～37个月(平均19. 3个月)随访,Rasmussen评分优19例,良21例,可4例,优良率90. 9%,其中Ⅴ型骨折膝关节评分优于Ⅵ型,两者比较有统计学意义(p <0. 05),植骨与不植骨患者关节面塌陷程度无明显差异(P <0.05)。并发症情况:1例出现深部感染,2例部分内固定物松动,1例长期膝关节疼痛。结论双钢板结合缝合锚钉可有效治疗胫骨平台双髁骨折,术后功能恢复与损伤程度密切相关。

Research of Frequency Discriminator on Frequency Lock Loops

Frequency lock loops （FLL） discriminating algorithms for direct-sequence spread-spectrum are discussed. The existing algorithms can＇t solve the problem of data bit reversal during one pre-detection integral period. And when the initial frequency offset is large, the frequency discriminator can＇ t work normally. To solve these problems, a new FLL discriminating algorithm is introduced. The least-squares discriminator is used in this new algorithm. As the least-squares discriminator has a short process unit period, the correspond- ing frequency discriminating range is large. And the data bit reversal just influence one process unit period, so the least-squares discriminated result will not be affected. Compared with traditional frequency discriminator, the least-squares algorithm can effectively solve the problem of data bit reversal and can endure larger initial frequency offset.

锁定加压钢板联合钛板法治疗胫骨平台双髁骨折

目的观察锁定加压钢板联合钛板法治疗胫骨平台双髁骨折的治疗效果。方法对26例Schatzker分类为Ⅴ型和Ⅵ型胫骨平台双髁骨折患者采用锁定加压钢板联合钛板切开复位内固定治疗;通过复查术后关节功能和影像资料判断手术效果。结果 Merchant膝关节功能评分:优16例,良5例,可、差5例,优良率为80.77%。结论锁定加压钢板联合钛板法治疗粉碎及移位的胫骨平台双髁骨折可以获得良好的解剖复位,术后膝关节能早期进行功能锻炼,减少并发症,是治疗胫骨平台双髁骨折安全有效的方法。

Endoscopic identification of endoluminal esophageal landmarks for radial and longitudinal orientation and lesion location

AIM To characterize esophageal endoluminal landmarks to permit radial and longitudinal esophageal orientation and accurate lesion location.METHODS Distance from the incisors and radial orientation were estimated for the main left bronchus and the left atrium landmarks in 207 consecutive patients using white light examination. A sub-study was also performed using white light followed by endoscopic ultrasound(EUS) in 25 consecutive patients to confirm the findings.The scope orientation throughout the exam was maintained at the natural axis,where the left esophageal quadrant corresponds to the area between 6 and 9 o'clock. When an anatomical landmark was identified, it was recorded with a photograph and its quadrant orientation and distance from the incisors were determined. The reference points to obtain the distances and radial orientation were as follows: the midpoint of the left main bronchus and the most intense pulsatile zone of the left atrium. With the video processor system set to moderate insufflation, measurements were obtained at the end of the patients' air expiration.RESULTS The left main bronchus and left atrium esophageal landmarks were identified using white light in 99% and 100% of subjects at a mean distance of 25.8 cm(SD2.3), and 31.4 cm(SD 2.4) from the incisors, respectively. The left main bronchus landmark was found to be a tubular, concave, non-pulsatile, esophageal external compression, occupying approximately 1/4 of the circumference. The left atrium landmark was identified as a round, convex, pulsatile, esophageal external compression, occupying approximately 1/4 of the circumference. Both landmarks were identified using white light on the anterior esophageal quadrant. In the substudy, the left main bronchus was identified in 24(92%) patients at 25.4 cm(SD2.1) and 26.7 cm(SD 1.9) from the incisors, by white light and EUS, respectively.The left atrium was recognized in all patients at 30.5 cm(SD 1.9), and 31.6 cm(SD2.3) from the incisors, by both white light and EUS, respectively. EUS confirmed that the landmarks corresponded to these two structures, respectively, and that they were located on the anterior esophageal wall. The Bland-Altman plot demonstrated high agreement between the white light and EUS measurements.CONCLUSION This study provides an endoscopic characterization of esophageal landmarks corresponding to the left main bronchus and left atrium, to permit radial and longitudinal orientation and accurate lesion location.

Is traumatic meniscal lesion associated with acute fracture morphology changes of tibia plateau? A series of arthroscopic analysis of 67 patients

BACKGROUND Computed tomography(CT)has become a routine preoperative examination for tibial plateau fractures(TPFs).Assessing the location of the fragment and intercondylar eminence fracture can provide clinicians with valuable information;however,the evaluation of traumatic meniscal lesion(TML)and arthroscopic management are controversial.AIM To predict TML by three-dimensional skeletal anatomy changes in unilateral TPF and bilateral TPF on preoperative thin layer CT.METHODS Acute fracture of tibial plateau patients undergoing arthroscopic surgery between December 2017 and December 2019 were included in this retrospective study.The type,zone,and location of TMLs were diagnosed based on the operation records and/or arthroscopic videos.Measurement of three-dimensional fracture morphology included the following:Frontal fragment width of plateau,sagittal fragment subsiding distance(FSD),sagittal fracture line distance,sagittal posterior tibial slope,and transversal area ratio of fragment area)on preoperative CT three-dimensional plane.The correlation of TML with skeletal values was calculated according to unicondylar TPFs and bicondylar TPFs.RESULTS A total of 67 patients were enrolled in this study,among which 30 patients had TMLs,lateral/medial(23/7).FSD was a particularly positive factor to predict TML,with odds ratio of 2.31(1.26-5.63).On sagittal view of CT,FSD degree of 8 mm and posterior tibial slope exceeding 11.74°implied enhanced risk of TML in bicondylar TPFs.On coronal view,once fragment width of plateau surpassed 3 cm,incidence of TML reached 100%.On transverse view,area ratio of fragment as enhanced risk of 5.5%and FSD>4.3 mm for predicting TML were observed in unicondylar TPFs.CONCLUSION TML can be predicted by different parameters on preoperative CT views according to unicondylar fractures and bicondylar TPFs.

后内侧和前外侧切口漂浮体位治疗胫骨平台双髁骨折的临床护理研究

目的探讨后内侧和前外侧切口漂浮体位治疗胫骨平台双髁骨折的临床护理。方法选取2011年6月至2013年6月在我院进行后内侧和前外侧切口漂浮体位治疗的胫骨平台双髁骨折患者40例,将两组患者分为接受常规护理的对照组和接受综合护理的观察组,各20例,比较两组患者住院时间、并发症情况及Rasmussen放射评分。结果观察组平均住院时间为(18.5±1.1)d,并发症发生率5.0%(1/20),均明显低于对照组的(23.6±0.9)d和35.0%(7/20),差异均具有统计学意义(均P<0.05);观察组膝关节功能评分情况显著优于对照组,差异有统计学意义(P<0.05)。结论胫骨平台双髁骨折患者正确有效的综合护理,有利于骨折固定保持良好稳定性,膝关节功能恢复好,减少并发症率,具有良好的临床价值和社会效益。

Sexual Dimorphism in Adult Human Mandible of North Indian Origin

Background: In forensic science the identification of a human is based on three important factors: Age, Sex and Stature. Bones are an important tool for it and among human bones the pelvis and the skull are the most reliable source for sex determination. In the absence of complete pelvis, mandi-ble becomes the important source for sex determination since mandible is the most durable and movable part of skull that can resist postmortem changes. The present study is conducted to assess the accuracy and role of few metric and morphological parameters in determination of the sex of dry adult human mandible of North Indian origin. Material & Methods: The Study is conducted on 50 dry intact human adult mandibles of North Indian origin. The metric parameters i.e. bigonial breadth, bicondylar breadth are measured with a Vernier Calliper by two observers. Non-metric parameters being observed are the morphological features like gonion flaring, muscular markings and shape of angle of symphysis menti. Result & Conclusion: It is concluded that bigonial breadth and bicondylar breadth exhibit the sexual dimorphism. Morphological Parameters: Gonion flaring, muscular markings and shape of angle of symphysis menti also demonstrate the sexual dimorphism. These parameters taken together may determine the sex of adult human mandibles. The present study shows that the mandible is an important tool in the determination of gender with high accuracy.

New Current Control Method of DC Power Supply for Magnetic Perturbation Coils on J-TEXT

In order to advance the research on suppressing tearing modes and driving plasma rotation, a DC power supply （PS） system has been developed for dynamic resonant magnetic perturbation （DRMP） coils and applied in the J-TEXT experiment. To enrich experimental phe- nomena in the J-TEXT tokamak, applying the circulating current four-quadrant operation mode in the DRMP DC PS system is proposed. By using the circulating current four-quadrant oper- ation, DRMP coils can be smoothly controlled without the dead-time when the current polarity reverses. Essential circuit analysis, control optimization and simulation of desired scenarios have been performed for normal current. Relevant simulation and test results are also presented.

Four-quadrant demodulation fiber sensor for wavelength monitoring of a wavelength phase-shifting interferometer

Real-time monitoring of wavelength is important for high-speed wavelength phase-shifting interferometry.In this paper,a wavelength sensor based on a polarization-maintaining fiber interferometer with four-quadrant demodulation was proposed.We built the wavelength sensing system with resolution better than 0.005 pm and 0.1 ms sampling interval and measured the response time of the tuned wavelength at 35 ms in the phase-shifting process of a commercial wavelength phase-shifting free-space interferometer,as well as the wavelength drift velocity of 0.01 pm per second in the hysteresis process.The optical fiber wavelength sensor with four-quadrant demodulation provides a real-time wavelength sensing scheme for high-speed wavelength phase-shifting interferometers.

伤骨再生汤联合双切口金属植入物内固定治疗胫骨平台双髁骨折临床观察

目的探讨伤骨再生汤联合双切口金属植入物内固定治疗胫骨平台双髁骨折的临床疗效及对膝关节功能的影响。方法将2017年6月—2018年9月收治的90例胫骨平台双髁骨折患者,随机分为2组,各45例。所有患者均行双切口金属植入物内固定治疗,对照组在此基础上给予骨康胶囊,观察组在对照组基础上给予伤骨再生汤,比较2组临床疗效、膝关节功能。结果治疗后,观察组总有效率(93.33%)明显高于对照组(73.33%),Rasmussen膝关节功能评分明显高于对照组,差异有统计学意义(P<0.05)。结论胫骨平台双髁骨折患者行双切口金属植入物内固定结合伤骨再生汤治疗,可有效促进患者膝关节功能恢复,利于骨折愈合。

A Novel Method to Simultaneously Measure the Straightness

A precise two-degree-of-freedom measuring system (2DMS) is developed based on single-mode optical fiber, LD, cube corner retroreflector and four-quadrant photodetector (4-Q), and the simultaneous on-line measurement of lateral and vertical direction straightness errors of the linear stage is carried out. The moving part is wireless, which eliminates any errors introduced by pushing and pulling the wires. The sensitivity of the straightness error measurement can be improved by a factor of 2 with the cube corner retroreflector. This fiber-based optically aligned beam is used to establish a reference line for the straightness measurement of any mechanical system. 4-Q detector is used to receive the laser beam. A chip microcomputer is developed to conduct all data acquisition and signal processing. The beam drift influence can be removed in the greatest extent from the system. The experiments on the measurement system stability, repeatability and its comparison with the HP5528 double-frequency laser interferometer are carried out.

双钢板内固定治疗胫骨平台双髁骨折的临床效果

目的探讨双钢板内固定治疗胫骨平台双髁骨折的临床效果。方法将我院收治的60例胫骨平台双髁骨折患者按照随机数表法分为观察组与对照组,各30例。观察组实施双钢板内固定治疗,对照组实施外侧锁定钢板内固定治疗。比较两组的治疗效果。结果观察组的住院时间、骨折愈合时间、负重时间均明显长于对照组(P<0.05)。观察组治疗优良率明显高于对照组(P<0.05)。手术前、后,两组的SOST、β-catenin水平无显著差异,且手术后两组间SOST、β-catenin水平均无显著差异(P>0.05)。观察组并发症总发生率明显低于对照组(P<0.05)。结论双钢板与外侧锁定钢板内固定在胫骨平台双髁骨折的治疗中均可取得较为理想的效果。双钢板内固定治疗更有利于患者早期膝功能锻炼,术后并发症更少,值得临床应用。

伤骨再生汤联合双切口金属植入物内固定治疗胫骨平台双髁骨折的临床疗效

目的探讨伤骨再生汤联合双切口金属植入物内固定法治疗胫骨平台双髁骨折患者的临床疗效。方法选取2019年5月至2020年5月本院收治的88例胫骨平台双髁骨折患者作为研究对象,按随机抽签法分为观察组和对照组,每组44例。对照组采用双切口金属植入物内固定法治疗,观察组在对照组基础上联合伤骨再生汤辅助治疗,比较两组临床疗效、Rasmussen放射学评分、Rasmusse膝关节功能评分、血清Ⅰ型胶原交联羧基末端肽(CTX)和Ⅰ型前胶原氨基端前肽(PINP)、血清炎症因子[白细胞介素-5(IL-5)、白细胞介素-6(IL-6)、白细胞介素-10(IL-10)]水平及并发症发生情况。结果观察组治疗总有效率(90.91%)高于对照组(72.73%),差异有统计学意义(P<0.05)。治疗后,两组Rasmussen放射学评分、Rasmusse膝关节功能评分均高于治疗前,且观察组高于对照组,差异有统计学意义(P<0.05)。治疗后,两组血清中CTX、PINP水平均低于治疗前,且观察组低于对照组,差异有统计学意义(P<0.05)。治疗后,两组血清IL-5、IL-6、IL-10水平均低于治疗前,且观察组低于对照组,差异有统计学意义(P<0.05)。观察组并发症发生率(4.55%)低于对照组(18.18%),差异有统计学意义(P<0.05)。结论伤骨再生汤联合双切口金属植入物内固定治疗胫骨平台双髁骨折效果显著,可有效改善患者膝关节功能及血清炎症因子水平,降低并发症发生率,安全性较高,具有较高的临床应用价值。

Paediatric conj oint bicondylar Hoffa fracture with patellar tend on injury: An unusual pattern of injury

Epiphyseal injuries of distal femur are rare with an incidence of 1%—6% among all physeal injuries. Prompt diagnosis and appropriate surgical treatment is crucial to achieve satisfactory functional outcomes. A conjoint bicondylar coronal split (Hoffa) fracture with complete transaction of ipsilateral patellar tendon has been reported in a 12 year old child. The injury was managed by open reduction and internal fixation and bone to ten don repair. This case emphasizes the need of accurate intraepiphyseal fixation for the management of these fractures in skeletally immature patients.