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 var...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.展开更多
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 co...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.展开更多
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 sam...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.展开更多
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 conde...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.展开更多
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 di...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.展开更多
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,...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.展开更多
基金Project supported by the National Natural Science Foundation of China(Nos.12022213,12002329,U23A2066,12272240,and 12002217)。
文摘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.
基金Supported by National Natural Science Foundation of China (No. 50878141)Hebei Natural Science Foundation,China (No. E2011202013)High School of Hebei Science and Technology Research Youth Foundation,China(No. Q2012083)
文摘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.
基金This work was supported by the National Natural Science Foundation of China(Grant No.29,070,196)and the Science Foundation of Polymer Physics Laboratory,Academia Sinica.
文摘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.
基金This work was supported by the National Natural Science Foundation of China(No.29974026)the Natural Science Foundation of Henan Province.
文摘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.
基金The work was supported by the National Natural Science Foundation of China.
文摘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.
文摘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.
