Thermal rectification is an exotic thermal transport phenomenon,an analog to electrical rectification,in which heat flux along one direction is larger than that in the other direction and is of significant interest in...Thermal rectification is an exotic thermal transport phenomenon,an analog to electrical rectification,in which heat flux along one direction is larger than that in the other direction and is of significant interest in electronic device applications.However,achieving high thermal rectification efficiency or rectification ratio is still a scientific challenge.In this work,we performed a systematic simulation of thermal rectification by considering both efforts of thermal conductivity asymmetry and geometrical asymmetry in a multi-segment thermal rectifier.It is found that the high asymmetry of thermal conductivity and the asymmetry of the geometric structure of multi-segment thermal rectifiers can significantly enhance the thermal rectification,and the combination of both thermal conductivity asymmetry and geometrical asymmetry can further improve thermal rectification efficiency.This work suggests a possible way for improving thermal rectification devices by asymmetry engineering.展开更多
This paper presents an enhanced version of the standard shooting method that enables problems with two unknown parameters to be solved.A novel approach is applied to the analysis of the natural vibrations of Euler-Ber...This paper presents an enhanced version of the standard shooting method that enables problems with two unknown parameters to be solved.A novel approach is applied to the analysis of the natural vibrations of Euler-Bernoulli beams.The proposed algorithm,named as two-parameter multiple shooting method,is a new powerful numerical tool for calculating the natural frequencies and modes of multi-segment prismatic and non-prismatic beams with different boundary conditions.The impact of the axial force and additional point masses is also taken into account.Due to the fact that the method is based directly on the fourth-order ordinary differential equation,the structures do not have to be divided into many small elements to obtain an accurate enough solution,even though the geometry is very complex.To verify the proposed method,three different examples are considered,i.e.,a three-segment non-prismatic beam,a prismatic column subject to non-uniformly distributed compressive loads,and a two-segment beam with an additional point mass.Numerical analyses are carried out with the software MATHEMATICA.The results are compared with the solutions computed by the commercial finite element program SOFiSTiK.Good agreement is achieved,which confirms the correctness and high effectiveness of the formulated algorithm.展开更多
Complex product development will inevitably face the design planning of the multi-coupled activities, and overlapping these activities could potentially reduce product development time, but there is a risk of the addi...Complex product development will inevitably face the design planning of the multi-coupled activities, and overlapping these activities could potentially reduce product development time, but there is a risk of the additional cost. Although the downstream task information dependence to the upstream task is already considered in the current researches, but the design process overall iteration caused by the information interdependence between activities is hardly discussed; especially the impact on the design process＇ overall iteration from the valid information accumulation process. Secondly, most studies only focus on the single overlapping process of two activities, rarely take multi-segment and multi-ply overlapping process of multi coupled activities into account; especially the inherent link between product development time and cost which originates from the overlapping process of multi coupled activities. For the purpose of solving the above problems, as to the insufficiency of the accumulated valid information in overlapping process, the function of the valid information evolution （VIE） degree is constructed. Stochastic process theory is used to describe the design information exchange and the valid information accumulation in the overlapping segment, and then the planning models of the single overlapping segment are built. On these bases, by analyzing overlapping processes and overlapping features of multi-coupling activities, multi-segment and multi-ply overlapping planning models are built; by sorting overlapping processes and analyzing the construction of these planning models, two conclusions are obtained： （1） As to multi-segment and multi-ply overlapping of multi coupled activities, the total decrement of the task set development time is the sum of the time decrement caused by basic overlapping segments, and minus the sum of the time increment caused by multiple overlapping segments; （2） the total increment of development cost is the sum of the cost increment caused by all overlapping process. And then, based on overlapping degree analysis of these planning models, by the V1E degree function, the four lemmas theory proofs are represented, and two propositions are finally proved： （1） The multi-ply overlapping of the multi coupled activities will weaken the basic overlapping effect on the development cycle time reduction （2） Overlapping the multi coupled activities will decrease product development cycle, but increase product development cost. And there is trade-off between development time and cost. And so, two methods are given to slacken and eliminate multi-ply overlapping effects. At last, an example about a vehicle upper subsystem design illustrates the application of the proposed models; compared with a sequential execution pattern, the decreasing of development cycle （22%） and the increasing of development cost （3%） show the validity of the method in the example The proposed research not only lays a theoretical foundation for correctly planning complex product development process, but also provides specific and effective operation methods for overlapping multi coupled activities.展开更多
Objective To evaluate the effect of double tractors swing microendoscopic discectomy technique in multisegmental lumbar disc herniation.Methods From December 2006 to November 2009,153 patients with multisegmental lumb...Objective To evaluate the effect of double tractors swing microendoscopic discectomy technique in multisegmental lumbar disc herniation.Methods From December 2006 to November 2009,153 patients with multisegmental lumbar disc herniation展开更多
This study explored the buckling of multiple intersecting spherical shells.A three-segment spherical shell was designed using the theory of deformation coordination;the design was compared with that of a volume-equiva...This study explored the buckling of multiple intersecting spherical shells.A three-segment spherical shell was designed using the theory of deformation coordination;the design was compared with that of a volume-equivalent cylindrical shell and ring-ribbed cylindrical shell.The numerical results indicated that the buckling capacity of the three-segment spherical shell was superior to those of the other two cylindrical shells.To validate our numerical approach,three laboratory-scale shell models were fabricated.Each model was accurately measured and slowly tested in a pressure chamber;thus,the tested shells were studied numerically.The experimental collapse modes agreed well with numerical results,and the collapse load of the three-segment pressure shell was considerably higher than that of the two cylindrical shells.展开更多
Objective:To observe clinical effects of pedicle screw fixation combined with cable wires and bone graft and cannulated compression screws on adult multi-segment lumbar spondylolysis.Methods:70 cases of patients with ...Objective:To observe clinical effects of pedicle screw fixation combined with cable wires and bone graft and cannulated compression screws on adult multi-segment lumbar spondylolysis.Methods:70 cases of patients with multi-segment lumbar spondylolysis were selected in our hospital.According to different surgical schemes,these patients were divided into the observation group(35 cases)and the control group(35 cases).The observation group received pedicle screw fixation combined with cable wires and bone graft and the control group received cannulated compression screw fixation.Macnab criteria were adopted to implement a therapeutic evaluation of two groups of patients to make an observation and comparison of the excellent and good rate of surgery and a series of indicators including perioperative clinical effects,intraoperative blood loss,duration of surgery,hospital length of stay(HLOS),visual analogue scale(VAS),Oswestry disability index and Japanese Orthopaedic Association(JOA)score.Results:The excellent and good rate of the observation group was 97.14%,and that of the control group was 82.86%,the difference between two groups was statistically significant(χ^(2)=6.248,p=0.012).The differences in intraoperative blood loss,duration of surgery and HLOS between two groups were statistically significant(t=-4.55,t=-4.55,t=-4.55;p<0.05).Oswestry index,VAS score and JOA score of the observation group were(2.4±0.9),(28.5±6.4)and(27.1±3.1)respectively,and these of the control group were(3.5±1.2),(37.1±7.8)and(21.3±2.7)respectively,the differences between two groups were statistically significant(t=4.338,t=5.043,t=8.347,p<0.05).Conclusions:Pedicle screw combined with immobilized implantation bone by wirerope has an excellent clinical effect on the treatment of adult multi-segment lumbar spondylolysis,and it has a series of advantages such as fast postoperative recovery,small surgical trauma and so on.In addition,this technique can also restore the stability of spinal segments and relieve pains to a greater degree.展开更多
The objective of maintaining the cleanliness of the multi-segment disk amplifier in Shenguang-II(SG-II) is to reduce laser-induced damage for optics. The flow field of clean gas, which is used for the transportation o...The objective of maintaining the cleanliness of the multi-segment disk amplifier in Shenguang-II(SG-II) is to reduce laser-induced damage for optics. The flow field of clean gas, which is used for the transportation of contaminant particles,is a key factor affecting the cleanliness level in the multi-segment disk amplifier. We developed a gas–solid coupling and three-dimensional flow numerical simulation model. The three-dimensional and two-phase flow model is verified by the flow-field smog experiment and the particle concentration measurement experiment with the 130-disk amplifier in SG-II. By optimizing the boundary conditions with the same flow rate, the multi-inlet vector flow scheme can not only effectively reduce the purging time, but also prevent the reverse diffusion of contaminant particles in the multi-segment disk amplifier and the deposition of contaminant particles on the surface of the Nd:glass.展开更多
Based on the mechanism of chromatographic retention (the relationship between the retention of solute and the mobile phase conditions) and method of resolution map, several methods of optimizing multi-segment linear g...Based on the mechanism of chromatographic retention (the relationship between the retention of solute and the mobile phase conditions) and method of resolution map, several methods of optimizing multi-segment linear gradient elution conditions were proposed according to the different separation requirements of various samples. These methods were verified using literature data. Moreover, the advantages and disadvantages of these methods were compared. It was proved that the third method is a fast optimization method which is capable of separating all the components with relatively high resolution.展开更多
A 14-bit low power self-timed differential successive approximation（SAR） ADC with an on-chip multisegment bandgap reference（BGR） is described.An on-chip multi-segment BGR,which has a temperature coefficient of 1.3...A 14-bit low power self-timed differential successive approximation（SAR） ADC with an on-chip multisegment bandgap reference（BGR） is described.An on-chip multi-segment BGR,which has a temperature coefficient of 1.3 ppm/℃and a thermal drift of about 100μV over the temperature range of -40 to 120℃is implemented to provide a high precision reference voltage for the SAR ADC.The Gray code form is utilized instead of binary form mode control to reduce substrate noise and enhance the linearity of the whole system.Self-timed bit-cycling is adopted to enhance the time efficiency.The 14-bit ADC was fabricated in a TSMC 0.13μm CMOS process. With the on-chip BGR,the SAR ADC achieves an SNDR of 81.2 dB（13.2 ENOB） and an SFDR of 85.2 dB with a conversion rate of 2 MS/s at room temperature and can keep an ENOB of more than 12 bits at a conversion rate of 2 MS/s over the temperature range from -40 to 120℃.展开更多
Strong earthquakes generally rupture along active faults,and associated ground motion can cause earthquake disasters,property losses,and casualties from kilometers to tens of kilometers away.Therefore,one of the most ...Strong earthquakes generally rupture along active faults,and associated ground motion can cause earthquake disasters,property losses,and casualties from kilometers to tens of kilometers away.Therefore,one of the most effective ways to find earthquake’s dangerous parts of faults is to study the seismic hazards on fault segments.After that,we can also evaluate the probabilities of landslides hazard,property losses,and casualties.In this study,using fault slip rates and magnitude-frequency relationship as constraints,we calculated the earthquake occurrence rates for the segments along the Xianshuihe-Xiaojiang fault zone.We obtained 11 sites of single-segment or multi-segment rupturing risk.We also provided these potential events conditional probabilities in the next 30 years.For the 11 potential earthquakes,we calculated the property loss of residential buildings in the ground motion field.The most significant property loss is CNY 7.65 billion caused by the single-segment rupturing of the F19 segment on the Anninghe fault.We applied the deep learning neural network method in predicting the number of casualties for the potential earthquakes,showing that the most significant event is the multi-segment rupturing of the F29 and F30 segments on the Anninghe fault with the predicted death number of 279-317.We also evaluated the probabilities of earthquake landslides after the potential earthquakes.The results show that areas with intense compressional tectonic stress are highly unstable and prone to earthquake induced landslides,including the southern section of the Yuke fault,the southern section of the Xianshuihe fault,and the conjugated area between the southern section of the Daliangshan fault and the Lianfeng fault.These areas have a considerable number of earthquake landslides with probabilities>10%.The methodology and results will give us a new effective way of applying active fault data in earthquake hazard and risk analysis and provide a scientific path for earthquake prevention,disaster reduction,and emergency rescue preparation.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant No.12274355)Xiamen University Malaysia Research Fund(Grant Nos.XMUMRF/2022C9/IORI/003 and XMUMRF/2022-C10/IORI/004)。
文摘Thermal rectification is an exotic thermal transport phenomenon,an analog to electrical rectification,in which heat flux along one direction is larger than that in the other direction and is of significant interest in electronic device applications.However,achieving high thermal rectification efficiency or rectification ratio is still a scientific challenge.In this work,we performed a systematic simulation of thermal rectification by considering both efforts of thermal conductivity asymmetry and geometrical asymmetry in a multi-segment thermal rectifier.It is found that the high asymmetry of thermal conductivity and the asymmetry of the geometric structure of multi-segment thermal rectifiers can significantly enhance the thermal rectification,and the combination of both thermal conductivity asymmetry and geometrical asymmetry can further improve thermal rectification efficiency.This work suggests a possible way for improving thermal rectification devices by asymmetry engineering.
文摘This paper presents an enhanced version of the standard shooting method that enables problems with two unknown parameters to be solved.A novel approach is applied to the analysis of the natural vibrations of Euler-Bernoulli beams.The proposed algorithm,named as two-parameter multiple shooting method,is a new powerful numerical tool for calculating the natural frequencies and modes of multi-segment prismatic and non-prismatic beams with different boundary conditions.The impact of the axial force and additional point masses is also taken into account.Due to the fact that the method is based directly on the fourth-order ordinary differential equation,the structures do not have to be divided into many small elements to obtain an accurate enough solution,even though the geometry is very complex.To verify the proposed method,three different examples are considered,i.e.,a three-segment non-prismatic beam,a prismatic column subject to non-uniformly distributed compressive loads,and a two-segment beam with an additional point mass.Numerical analyses are carried out with the software MATHEMATICA.The results are compared with the solutions computed by the commercial finite element program SOFiSTiK.Good agreement is achieved,which confirms the correctness and high effectiveness of the formulated algorithm.
基金sponsored by Jiangsu Provincial Colleges and Universities Natural Science Foundation of China (Grant No.08KJD410001)Humanities and Social Sciences Planning Fund of Ministry of Education of China (Grant No. 12YJAZH151)Humanities and Social Sciences Youth Fund of Ministry of Education of China (Grant No. 12YJCZH209)
文摘Complex product development will inevitably face the design planning of the multi-coupled activities, and overlapping these activities could potentially reduce product development time, but there is a risk of the additional cost. Although the downstream task information dependence to the upstream task is already considered in the current researches, but the design process overall iteration caused by the information interdependence between activities is hardly discussed; especially the impact on the design process＇ overall iteration from the valid information accumulation process. Secondly, most studies only focus on the single overlapping process of two activities, rarely take multi-segment and multi-ply overlapping process of multi coupled activities into account; especially the inherent link between product development time and cost which originates from the overlapping process of multi coupled activities. For the purpose of solving the above problems, as to the insufficiency of the accumulated valid information in overlapping process, the function of the valid information evolution （VIE） degree is constructed. Stochastic process theory is used to describe the design information exchange and the valid information accumulation in the overlapping segment, and then the planning models of the single overlapping segment are built. On these bases, by analyzing overlapping processes and overlapping features of multi-coupling activities, multi-segment and multi-ply overlapping planning models are built; by sorting overlapping processes and analyzing the construction of these planning models, two conclusions are obtained： （1） As to multi-segment and multi-ply overlapping of multi coupled activities, the total decrement of the task set development time is the sum of the time decrement caused by basic overlapping segments, and minus the sum of the time increment caused by multiple overlapping segments; （2） the total increment of development cost is the sum of the cost increment caused by all overlapping process. And then, based on overlapping degree analysis of these planning models, by the V1E degree function, the four lemmas theory proofs are represented, and two propositions are finally proved： （1） The multi-ply overlapping of the multi coupled activities will weaken the basic overlapping effect on the development cycle time reduction （2） Overlapping the multi coupled activities will decrease product development cycle, but increase product development cost. And there is trade-off between development time and cost. And so, two methods are given to slacken and eliminate multi-ply overlapping effects. At last, an example about a vehicle upper subsystem design illustrates the application of the proposed models; compared with a sequential execution pattern, the decreasing of development cycle （22%） and the increasing of development cost （3%） show the validity of the method in the example The proposed research not only lays a theoretical foundation for correctly planning complex product development process, but also provides specific and effective operation methods for overlapping multi coupled activities.
文摘Objective To evaluate the effect of double tractors swing microendoscopic discectomy technique in multisegmental lumbar disc herniation.Methods From December 2006 to November 2009,153 patients with multisegmental lumbar disc herniation
基金This study was supported by the National Natural Science Foundation of China(Grant numbers 51709132 and 51679133),Jiangsu Provincial Government Scholarship Programme,and the“Construction of a Leading Innovation Team”project by Hangzhou City Government.
文摘This study explored the buckling of multiple intersecting spherical shells.A three-segment spherical shell was designed using the theory of deformation coordination;the design was compared with that of a volume-equivalent cylindrical shell and ring-ribbed cylindrical shell.The numerical results indicated that the buckling capacity of the three-segment spherical shell was superior to those of the other two cylindrical shells.To validate our numerical approach,three laboratory-scale shell models were fabricated.Each model was accurately measured and slowly tested in a pressure chamber;thus,the tested shells were studied numerically.The experimental collapse modes agreed well with numerical results,and the collapse load of the three-segment pressure shell was considerably higher than that of the two cylindrical shells.
基金supported by the Visiting Scholar Foundation of Key Laboratory of New Technology for Construction of Cities in Mountain Area in Chongqing University, China
文摘Objective:To observe clinical effects of pedicle screw fixation combined with cable wires and bone graft and cannulated compression screws on adult multi-segment lumbar spondylolysis.Methods:70 cases of patients with multi-segment lumbar spondylolysis were selected in our hospital.According to different surgical schemes,these patients were divided into the observation group(35 cases)and the control group(35 cases).The observation group received pedicle screw fixation combined with cable wires and bone graft and the control group received cannulated compression screw fixation.Macnab criteria were adopted to implement a therapeutic evaluation of two groups of patients to make an observation and comparison of the excellent and good rate of surgery and a series of indicators including perioperative clinical effects,intraoperative blood loss,duration of surgery,hospital length of stay(HLOS),visual analogue scale(VAS),Oswestry disability index and Japanese Orthopaedic Association(JOA)score.Results:The excellent and good rate of the observation group was 97.14%,and that of the control group was 82.86%,the difference between two groups was statistically significant(χ^(2)=6.248,p=0.012).The differences in intraoperative blood loss,duration of surgery and HLOS between two groups were statistically significant(t=-4.55,t=-4.55,t=-4.55;p<0.05).Oswestry index,VAS score and JOA score of the observation group were(2.4±0.9),(28.5±6.4)and(27.1±3.1)respectively,and these of the control group were(3.5±1.2),(37.1±7.8)and(21.3±2.7)respectively,the differences between two groups were statistically significant(t=4.338,t=5.043,t=8.347,p<0.05).Conclusions:Pedicle screw combined with immobilized implantation bone by wirerope has an excellent clinical effect on the treatment of adult multi-segment lumbar spondylolysis,and it has a series of advantages such as fast postoperative recovery,small surgical trauma and so on.In addition,this technique can also restore the stability of spinal segments and relieve pains to a greater degree.
基金supported by the National Natural Science Foundation of China (Grant No. 61505228)
文摘The objective of maintaining the cleanliness of the multi-segment disk amplifier in Shenguang-II(SG-II) is to reduce laser-induced damage for optics. The flow field of clean gas, which is used for the transportation of contaminant particles,is a key factor affecting the cleanliness level in the multi-segment disk amplifier. We developed a gas–solid coupling and three-dimensional flow numerical simulation model. The three-dimensional and two-phase flow model is verified by the flow-field smog experiment and the particle concentration measurement experiment with the 130-disk amplifier in SG-II. By optimizing the boundary conditions with the same flow rate, the multi-inlet vector flow scheme can not only effectively reduce the purging time, but also prevent the reverse diffusion of contaminant particles in the multi-segment disk amplifier and the deposition of contaminant particles on the surface of the Nd:glass.
基金This work was supported by the National Natural Science Foundation of China (Grant No. 20175029).
文摘Based on the mechanism of chromatographic retention (the relationship between the retention of solute and the mobile phase conditions) and method of resolution map, several methods of optimizing multi-segment linear gradient elution conditions were proposed according to the different separation requirements of various samples. These methods were verified using literature data. Moreover, the advantages and disadvantages of these methods were compared. It was proved that the third method is a fast optimization method which is capable of separating all the components with relatively high resolution.
文摘A 14-bit low power self-timed differential successive approximation（SAR） ADC with an on-chip multisegment bandgap reference（BGR） is described.An on-chip multi-segment BGR,which has a temperature coefficient of 1.3 ppm/℃and a thermal drift of about 100μV over the temperature range of -40 to 120℃is implemented to provide a high precision reference voltage for the SAR ADC.The Gray code form is utilized instead of binary form mode control to reduce substrate noise and enhance the linearity of the whole system.Self-timed bit-cycling is adopted to enhance the time efficiency.The 14-bit ADC was fabricated in a TSMC 0.13μm CMOS process. With the on-chip BGR,the SAR ADC achieves an SNDR of 81.2 dB（13.2 ENOB） and an SFDR of 85.2 dB with a conversion rate of 2 MS/s at room temperature and can keep an ENOB of more than 12 bits at a conversion rate of 2 MS/s over the temperature range from -40 to 120℃.
基金supported by the National Natural Science Foundation of China(Grant Nos.41941016,42074064,and U2039201)the National Institute of Natural Hazards,Ministry of Emergency Management of China(Grant No.ZDJ2020-14).
文摘Strong earthquakes generally rupture along active faults,and associated ground motion can cause earthquake disasters,property losses,and casualties from kilometers to tens of kilometers away.Therefore,one of the most effective ways to find earthquake’s dangerous parts of faults is to study the seismic hazards on fault segments.After that,we can also evaluate the probabilities of landslides hazard,property losses,and casualties.In this study,using fault slip rates and magnitude-frequency relationship as constraints,we calculated the earthquake occurrence rates for the segments along the Xianshuihe-Xiaojiang fault zone.We obtained 11 sites of single-segment or multi-segment rupturing risk.We also provided these potential events conditional probabilities in the next 30 years.For the 11 potential earthquakes,we calculated the property loss of residential buildings in the ground motion field.The most significant property loss is CNY 7.65 billion caused by the single-segment rupturing of the F19 segment on the Anninghe fault.We applied the deep learning neural network method in predicting the number of casualties for the potential earthquakes,showing that the most significant event is the multi-segment rupturing of the F29 and F30 segments on the Anninghe fault with the predicted death number of 279-317.We also evaluated the probabilities of earthquake landslides after the potential earthquakes.The results show that areas with intense compressional tectonic stress are highly unstable and prone to earthquake induced landslides,including the southern section of the Yuke fault,the southern section of the Xianshuihe fault,and the conjugated area between the southern section of the Daliangshan fault and the Lianfeng fault.These areas have a considerable number of earthquake landslides with probabilities>10%.The methodology and results will give us a new effective way of applying active fault data in earthquake hazard and risk analysis and provide a scientific path for earthquake prevention,disaster reduction,and emergency rescue preparation.
