Theoretical and experimental investigations on an X-shaped vibration isolator with active controlled variable stiffness

A novel X-shaped variable stiffness vibration isolator(X-VSVI)is proposed.The Runge-Kutta method,harmonic balance method,and wavelet transform spectra are introduced to evaluate the performance of the X-VSVI under various excitations.The layer number,the installation angle of the X-shaped structure,the stiffness,and the active control parameters are systematically analyzed.In addition,a prototype of the X-VSVI is manufactured,and vibration tests are carried out.The results show that the proposed X-VSVI has a superior adaptability to that of a traditional X-shaped mechanism,and shows excellent vibration isolation performance in response to different amplitudes and forms of excitations.Moreover,the vibration isolation efficiency of the device can be improved by appropriate adjustment of parameters.

Modeling,analysis,and simulation of X-shape quasi-zero-stiffness-roller vibration isolators

Existing quasi-zero stiffness(QZS)isolators are reviewed.In terms of their advantages,a novel X-shape QZS isolator combined with the cam-roller-spring mechanism(CRSM)is proposed.Different from the existing X-shape isolators,oblique springs are used to enhance the negative stiffness of the system.Meanwhile,the CRSM is used to eliminate the gravity of the loading mass,while the X-shape structure leaves its static position.The existing QZS isolators are demonstrated and classified according to their nonlinearity mechanisms and classical shapes.It is shown that the oblique spring can realize negative stiffness based on the simplest mechanism.The X-shape has a strong capacity of loading mass,while the CRSM can achieve a designed restoring force at any position.The proposed isolator combines all these advantages together.Based on the harmonic balance method(HBM)and the simulation,the displacement transmissibilities of the proposed isolator,the X-shape isolators just with oblique springs,and the X-shape isolators in the traditional form are studied.The results show that the proposed isolator has the lowest beginning isolation frequency and the smallest maximum displacement transmissibility.However,it still has some disadvantages similar to the existing QZS isolators.This means that its parameters should be designed carefully so as to avoid becoming a bistable system,in which there are two potential wells in the potential energy curve and thus the isolation performance will be worsened.

Seismic Behavior of Specially Shaped Column Joints with X-Shaped Reinforcement

To investigate the seismic behavior of specially shaped column joints with X-shaped reinforcement,two groups of specimens with or without X-shaped reinforcement in joint core region were tested under constant axial compression load and low reversed cyclic loading,which imitated low to moderate earthquake force.The seismic behavior of specially shaped column joints with X-shaped reinforcement in terms of bearing capacity,displacement,ductility,hysteretic curve,stiffness degradation and energy dissipation was studied and compared to that without Xshaped reinforcement in joint core region.With the damage estimation model,the accumulated damage was analyzed.The shearing capacity formula of specially shaped column joints reinforced by X-shaped reinforcement was proposed with a simple form.The test results show that X-shaped reinforcement is an effective measure for improving the seismic behavior of specially shaped column joints including deformation behavior,ductility and hysteretic characteristic.All specimens were damaged with gradual stiffness degeneration.In addition,X-shaped reinforcement in the joint core region is an effective way to lighten the degree of cumulated damage.The good seismic performance obtained from the specially shaped column joint with X-shaped reinforcement can be used in engineering applications.The test value is higher than the calculated value,which indicates that the formula is safe for the design of specially shaped column joints.

TRANSITIONS AND MODRPHOLOGY OF MAIN-CHAIN LIQUID CRYSTALLINE POLYMERS WITH X-SHAPED MESOGENS

The transitions and morphology of a series of main-chain liquid crystalline polymer with X-shaped mesogens were studied by means of DSC,SALS and polarizing microscopy techniques. Aneven-odd effect was observed for samples with different size of the substituents on the mesogenends. The isotropization process was similar to that of main-chain polymers with rod-likemesogens. No crystallization was detected for specimens cooling down from their isotropic meltstate. However two of the samples may crystallize in cooling process directly from the liquidcrystalline state.

SYNTHESIS OF MAIN CHAIN LIQUID CRYSTALLINE COPOLYESTERS WITH X-SHAPED TWO-DIMENSIONAL MESOGENIC UNIT AND CROWN ETHER CYCLE

A novel series of main chain liquid crystalline copolyesters with X-shaped two-dimensional mesogenic unit and crown ether cycle of cis-4,4＇-bis（4-hydroxyphenylazo） dibenzo-18-crown-6 was prepared via solution condensation polymerization from 4,4＇-（a;arhexanedioyloxy） dibenzoyl dichloride （MI）, 2,5-bis（p-octyloxybenzoyloxy） hydro-quinone （M2） and cis-4,4＇-bis（4-hydroxyphenylazo） dibenzo-18-crown-6 （M3）. Monomer MI was synthesized by esterification and substitution of adipoyl chloride with p-hydroxybenzoic acid, monomer M2 was synthesized by esterfication and reduction reaction of 2,5-dihydroxybenzoquinone and p-octanoxybenzoyl chloride and monomer M3 was synthesized by diazotization and coupling reaction of cis-diaminodibenzo-18-crown-6 with phenol. The molecular weights of copolyesters are not high, and the intrinsic viscosity [η] of copolyesters ranges from 0.25-0.35. The monomers＇ structures were identified by using elemental analysis, IR, UV, ^1H-NMR, MS, etc. All the copolyesters are yellowish powders and insoluble in THF and CHC13 at room temperature except cPg. The properties of copolyesters were investigated by using GPC, [η] , DSC, TG, WAXD and POM. It was found that all the copolyesters entered into liquid crystal phase when they were heated to above their melting temperature （Tin）. The typical smectic and nematic phase texture can be observed on POM. Their mesophase transition temperature and thermal stability change regularly with varying the content of cis-4,4＇-bis（4-hydroxyphenylazo） dibenzo-18-crown-6 unit in the copolyesters.

SYNTHESIS AND CHARACTERIZATION OF MAIN CHAIN AROMATIC LIQUID CRYSTAL COPOLYESTERS WITH X-SHAPED AND ROD-SHAPED MESOGENIC UNITS

A series of main chain liquid crystal aromatic copolyesters with X-shaped and rod-shaped mesogenic units were synthesized via solution condensation polymerizations of 4,4'-(alpha,omega-octanedioyloxy)-dibenzoyl dichlorides with 2,5-bis(p-octanoxy benzoyloxy)-hydroquinone and diphenol. All of the copolyesters showed thermotropic liquid crystalline behaviors through observations using DSC, polarized microscopy and X-ray diffraction. The melting point (T-m) and the isotropization temperature (T-i) change regularly with varying the content of diphenol unit in the copolymers.

The review of clinical application of X-shaped balance acupuncture therapy for joint pain and activity disorder

Musculoskeletal diseases such as neck, shoulder, back and leg pain are ext remely common in clinic. Diseases of the joints of the ext remi ti es, especially sputum, wr ist spr ains, and periarthritis of the shoulders, and even lumbar disc herniation, use X-shaped balance acupuncture therapy to relieve pain and improve motor function. The method of obtaining acupoints is simple and easy to operate. Many of clinical comparison shows that this therapy is simple to conventional acupuncture and moxibustion in the treatment of local pain and joint diseases. This review concluded the advantaged about the X-shaped balance acupuncture therapy and it worth to clinical promotion.

子宫背带式缝合术在剖宫产患者产后出血中的应用效果

目的探讨子宫背带式缝合术在剖宫产患者产后出血治疗中的应用价值。方法 16例因宫缩乏力行剖宫产产后出血患者分为宫腔纱布填塞组(14例)和子宫背带式缝合组(12例),对2组患者手术结果、手术时间、产后出血量、术后病率进行比较。结果 2组患者均顺利完成手术,术后无因血液循环不良或再出血而再次手术者,术后切口均甲级愈合;产后42 d复查体检未发现异常,子宫复旧正常。与宫腔纱布填塞组比较,子宫背带式缝合组手术时间短,产后出血量少,术后病率低(P<0.05);2组均随访3～12个月无远期并发症发生。结论子宫背带式缝合术用于治疗剖宫产患者产后出血具有手术时间短、止血迅速、并发症少等优点,是治疗剖宫产患者产后出血的有效方法。

宫颈捆扎联合X形子宫缝扎术治疗剖宫产产后出血的研究

目的:探讨剖宫产术中宫颈捆扎联合X形子宫缝扎术治疗剖宫产产后出血的效果。方法:将40例剖宫产术中发生产后出血的患者随机分为实验组(20例)和对照组(20例)。实验组行宫颈捆扎联合X形子宫缝扎术;对照组行"8"字缝合,结扎双侧子宫动脉,宫腔填塞纱条。结果:实验组在平均出血量、平均手术时间、子宫切除、产褥病率方面明显优于对照组,差异有高度统计学意义(P<0.01);两组无一例因血液循环不良或再出血而行二次手术或子宫切除。结论:宫颈捆扎联合X形子宫缝扎术具有操作简单、止血迅速、安全易行等优点,治疗剖宫产产后出血效果显著。

新式多发性子宫肌瘤剔除子宫重建术1例(病例报道并文献复习)

目的介绍一种新式子宫肌瘤剔除术并行子宫重建的操作方法,并观察其疗效。方法对1例要求保留生育功能的多发性子宫肌瘤患者采取了该手术方法。术中探查盆腔及子宫后,子宫肌内注射垂体后叶素6 U(30 mL),将止血带穿过双侧阔韧带无血管区环绕宫颈,暂时阻断双侧子宫动脉血供,切开子宫后壁肌层剥离瘤体,瘤体剔除干净后行子宫重建(“三瓣法”缝合)。结果患者手术过程顺利,如期出院。术后1个月随访阴道彩超提示子宫肌层分布不均,未见其他异常,现仍在随访中。结论子宫肌瘤剔除+“三瓣法”缝合子宫重建,是有生育要求的多发性子宫肌瘤患者的可选方法之一。

Obstetrical Fistula: Clinical, Therapeutic and Prognostic Aspects at the Gynecology and Obstetrics Department of Borgou University Hospital Center in Benin

Introduction: Obstetric Fistula (OF) is a tragedy and a public health problem (physical, social, moral and psychological). Objective: To determine the clinical, therapeutic and prognostic aspects of obstetric fistula at CHUD/B-A maternity ward in 2016. Study Method: This is a descriptive, analytic study with prospective data collection from March 07 to December 31, 2016. Patients with obstetric fistula were the study population. Results: A total of 37 patients were treated including 35 operated, the other two not operated for pyuria and bladder calculus after examination under spinal anesthesia. The average age was 36.6 ± 10.5 years with the extremes of 21 years and 65 years. The mean age of onset of Obstetric Fistula (OF) was 28.9 ± 6.5 years. Patients came from southern Benin (51.4%), were married (67.6%), peasant (35.1%) and out of school (81.1%). The types of OF were vesico-vaginal fistula (VVF) (62.2%), urethro-vaginal fistula (24.3%), vesico-uterine fistula (VUF) (5.4%), and uretero-vaginal fistula (2.7%). The fistula site was supra trigonal (54.1%), urethral (18.9%), trigonal (10.8%), vesico-uterine (10.8%), cervical urethral (2.7%), ureteroid vaginal (2.7%). Fistulas were complex (70.3%), complicated (24.3%) and simple (5.4%). The vaginal route was one of the first routes (64.9%). The operative techniques used were CHASSAR MOIR hysterorrhaphy (74.3%). The cure with continence was 68.6%. Conclusion: OF is observed in young women of childbearing age. VVF is the most common. The management is surgical with several operating techniques. Healing is possible. Hence the importance of paying special attention to these patients for their care.

子宫背带式缝合术对剖宫产产后出血的治疗效果及对术中出血量和下床活动时间的影响

目的探究子宫背带式缝合术对剖宫产产后出血的治疗效果及对术中出血量和下床活动时间的影响。方法选取2013年3月至2017年9月扬州大学附属六合区人民医院诊治的、符合纳入标准的50例剖宫产患者为研究对象,按照不同治疗方法将其分为观察组和对照组,每组25例患者。观察组患者行子宫背带式缝合术治疗,对照组患者行传统填塞纱布治疗。分析并比较两组患者产后手术时间、术中出血量、下床活动时间。结果观察组患者手术时间、术中总出血量、下床活动时间、恶露持续时间和住院时间均低于对照组患者,其差异均具有统计学意义(t=6.58、17.49、7.77、4.99、10.24,均P<0.01);两组患者术后阴道出血量差异无统计学意义(t=1.59,P=0.12);观察组患者宫缩持续时间多于对照组患者,其差异具有统计学意义(t=3.99,P<0.01);随着时间的推移,两组患者子宫底下降高度均有所改善,其差异具有统计学意义(F=4.06,P=0.04);观察组患者子宫底下降高度均高于对照组患者,其差异具有统计学意义(F=5.57,P=0.02);观察组患者术后并发症发生率低于对照组患者,其差异具有统计学意义(χ~2=5.88,P=0.02)。结论子宫背带式缝合术能够有效降低剖宫产术中出血量,缩短手术时间和下床活动时间,值得临床推广。

子宫缝合术联合卡前列素氨丁三醇治疗子宫收缩乏力性产后出血的临床疗效观察

目的研究子宫缝合术联合卡前列素氨丁三醇治疗子宫收缩乏力产后出血的临床疗效。方法将90例子宫收缩乏力性产后出血患者随机分为两组,对照组经B-Lynch缝合术治疗,观察组在此基础上联合卡前列素氨丁三醇治疗。结果观察组术后2 h出血量、术后24 h出血量、FSH水平上显著低于对照组,观察组子宫内膜厚度为(5.6±0.9)mm,显著高于对照组;观察组失眠、疲乏、眩晕及潮热出汗症状评分分别为(0.33±0.02)分、(0.37±0.05)分、(0.21±0.04)分、(0.48±0.03)分,均显著低于对照组,差异有统计学意义(P<0.05)。两组子宫切除率及产褥病比较,差异无统计学意义(P>0.05)。结论子宫收缩乏力性产后出血经子宫缝合术联合卡前列素氨丁三醇治疗,可有效减少患者术后出血量,缓解其不良症状,预后效果良好。

Hybrid Passive/Active Vibration Control of a Loosely Connected Spacecraft System

In this paper,a hybrid passive/active vibration(HPAV)controller of a loosely connected spacecraft consisting of a servicing satellite,a target and an X-shape structure isolator is first proposed to suppress vibrations of the system when subjected to the impulsive external excitations during the on-orbit missions.The passive dynamic response of the combined system can be adjusted appropriately to achieve the desired vibration isolation performance by tuning the structural parameters of the bio-inspired X-shape structure.Moreover,the adaptive control design through dynamic scaling technique is selected as the active component to maintain high vibration isolation performance in the presence of parameter uncertainties such as mass of the satellite platform,the damping and rotation friction coefficients of the X-shape structure.Compared with the pure passive system and the traditional spring-mass-damper(SMD)isolator,the HPAV strategy witnesses lower transmissibility,smaller vibration amplitude and higher convergence rate when subjected to the post-capture impact.Numerical simulations demonstrate the feasibility and validity of the proposed hybrid control scheme in suppressing vibrations of the free-floating spacecraft.

欣母沛联合改良B-Lynch子宫缝合术治疗剖宫产难治性子宫收缩乏力性产后出血效果观察

目的了解欣母沛联合改良B-Lynch子宫缝合术治疗剖宫产难治性子宫收缩乏力性产后出血的临床疗效。方法以随机法将方便选取该院2013年1月—2017年10月接收且行剖宫产后出现难治性子宫收缩乏力性产后出血的105例患者分成2组:选欣母沛+常规子宫缝合术治疗的53例为对照组,选欣母沛+改良B-Lynch子宫缝合术治疗的52例为治疗组,对比2组治疗效果。结果治疗组有效率96.15%,与对照组81.13%相比,差异有统计学意义(χ2=5.851;P<0.05);2组术中出血量、手术用时对比,差异无统计学意义(P>0.05);治疗组术后24 h出血量(368.52±22.16)m L,少于对照组(441.36±20.56)m L,术后血红蛋白水平(87.52±2.46)g/L,也比对照组(78.64±3.49)g/L高(t=-17.465、15.043;P<0.05)。结论对行剖宫产术后出现难治性子宫收缩乏力性产后出血患者,联用欣母沛、改良B-Lynch子宫缝合术治疗,效果确切。

探讨不同术式治疗子宫切口憩室的临床疗效

目的探讨不同手术方式治疗子宫切口憩室的临床疗效。方法回顾性分析2014年8月-2017年8月于我科进行手术治疗的30例子宫切口憩室患者,根据手术方式的不同,分为观察组(宫腹腔镜联合下子宫切口憩室切除加子宫修补术);对照组(阴式子宫切口憩室切除加子宫修补术);每组15例患者,比较两组临床资料,手术指标(术中出血量、术后胃肠功能恢复时间、术后住院天数)以及随访指标(经期恢复情况及再孕率)。结果两组临床资料差异无统计学意义(P>0.05),观察组手术时间、术中出血量、术后住院天数均少于对照组(P<0.05),两组术后月经时间及再妊娠率差异无统计学意义(P>0.05)。结论宫腹腔镜联合下子宫切口憩室切除加子宫修补术手术时间短、术中出血少、给患者带来的创伤小,术后患者恢复快、住院时间短。

Vibration isolation performance analysis of a bilateral supported bio-inspired anti-vibration control system

To achieve better anti-vibration performance in a low frequency region and expand the range of vibration isolation,a bilateral supported bio-inspired anti-vibration(BBAV)structure composed of purely linear elements is proposed,inspired by the motion form of bird legs and the nonlinear extension and compression of muscles and tendons.The kinematic relations and nonlinear dynamic model considering vertical and rotational vibrations are established.The loading capacity and equivalent stiffness are investigated with key parameters.The amplitude-frequency characteristics and force transmissibility are used to evaluate the stability and anti-vibration performance with the effects of the excitation amplitude,rod length,installation angle,and spring stiffness.The results show that the loading requirements and resonant characteristics of the BBAV structure are adjustable,and superior vibration isolation performance can be achieved readily by tuning the parameters.The X-shaped vibration structure is sensitive to the spring stiffness,which exhibits a wider vibration isolation bandwidth with smaller spring stiffness.Besides,depending on the parameters,the nonlinear behavior of the BBAV system can be interconverted between the softening type and the hardening type.The theoretical analysis in this study demonstrates the advantages and effectiveness of the vibration isolation structure.

B-Lynch子宫缝合术治疗宫缩乏力性剖宫产手术产后出血的临床效果及预后分析

目的探讨分析采用B-Lynch子宫缝合术治疗宫缩乏力性剖宫产手术产后出血的临床效果及预后。方法选取该院收治的宫缩乏力性剖宫产手术产后出血患者48例作为研究对象,病例来源于2014年1月—2016年12月,回顾性分析临床资料,按照治疗方法分为两组,其中采用常规药物治疗24例为A组,在用B-Lynch子宫缝合术方式治疗24例为B组。对两组的治疗效果进行回顾性对比分析。结果 A组的手术时间(29.8±6.3)min、术中出血量(1 100±160.0)mL、以及住院时间(8.1±0.8)d,B组的手术时间(13.3±1.2)min、术中出血量(850±140.0)mL、以及住院时间(4.3±1.2)d,(t=12.604,5.761,12.908,P=0.000),B组的手术时间、术中出血量及住院时间等各项手术指标值均明显低于A组(P<0.05),其中A组的输血率为25.00%(6/24),B组的输血率为4.17%(1/24)(χ~2=4.181,P=0.041)。结论 B-Lynch子宫缝合术用于治疗宫缩乏力性剖宫产手术产后出血具有非常显著的临床效果。

Constructal entransy dissipation rate minimization for X-shaped vascular networks

Combining with entransy theory, constructal designs of the X-shaped vascular networks(XSVNs) are implemented with fixed total tube volumes of the XSVNs. The entransy dissipation rates(EDRs) of the XSVNs are minimized, and the optimal constructs of the XSVNs are derived. Comparison of the optimal constructs of the XSVNs with two optimization objectives(EDR minimization and entropy generation rate(EGR) minimization) is conducted. It is found that when the dimensionless mass flow rate(DMFR) is small, the optimal diameter ratio of the elemental XSVN derived by EDR minimization is different from that derived by EGR minimization. For the multilevel XSVN, when the DMFR is 100, compared the XSVN with the corresponding H-shaped vascular network(HSVN), the dimensionless EDRs of the elemental, second and fourth order XSVNs are reduced by 26.39%, 15.34% and 9.81%, respectively. Compared with the entransy dissipation number(EDN) of the second order XSVN before angle optimization, the EDN after optimization is reduced by 26.15%, which illustrates that it is significant to conduct angle optimization of the XSVN. Entransy theory is applied into the constructal design of the vasculature with heat transfer and fluid flow in this paper, which provides new directions for the vasculature designs.

RELATIONSHIP OF FIRST STEP HEIGHT,STEP SLOPE AND CAVITY IN X-SHAPED FLARING GATE PIERS

The energy dissipation of X-shaped flaring gate piers ahead of a stepped spillway was adopted in the Suofengying Hydroplant. Under the circumstance that the first step is higher than others, at the step surface an aerated cavity occured behind piers. The interaction of the weir head, the elevation difference between crest and chamber outlet, the first step height, the slopes of weir end and step, and the size of cavity, was investigated, the expression was derived to characterize their relationship, and the corresponding curves were plotted. The comparison of the calculated and simulated results with the measured data was performed. When the slopes of step and weir end are equivalent, the relative height difference between the first and second steps becomes the main factor influencing the aerated cavity. These findings may be useful in practical applications.