Cable with discrete negative stiffness device and viscous damper: passive realization and general characteristics

Lin Chen,Limin Sun,Satish Nagarajaiah 국제구조공학회 2015 Smart Structures and Systems, An International Jou Vol.15 No.3

Negative stiffness, previously emulated by active or semi-active control for cable vibrationmitigation, is realized passively using a self-contained highly compressed spring, the negative stiffnessdevice (NSD).The NSD installed in parallel with a viscous damper (VD) in the vicinity of cable anchorage,enables increment of damper deformation during cable vibrations and hence increases the attainable cabledamping. Considering the small cable displacement at the damper location, even with the weakening device,the force provided by the NSD-VD assembly is approximately linear. Complex frequency analysis has thusbeen conducted to evaluate the damping effect of the assembly on the cable; the displacement-dependentnegative stiffness is further accounted by numerical analysis, validating the accuracy of the linearapproximation for practical ranges of cable and NSD configurations. The NSD is confirmed to be a practicaland cost-effective solution to improve the modal damping of a cable provided by an external damper,especially for super-long cables where the damper location is particularly limited. Moreover, mathematically,a linear negative stiffness and viscous damping assembly has proven capability to represent active orsemi-active control for simplified cable vibration analysis as reported in the literature, while in these studiesonly the assembly located near cable anchorage has been addressed. It is of considerable interest tounderstand the general characteristics of a cable with the assembly relieving the location restriction, since itis quite practical to have an active controller installed at arbitrary location along the cable span such as byhanging an active tuned mass damper. In this paper the cable frequency variations and damping evolutionswith respect to the arbitrary assembly location are then evaluated and compared to those of a taut cable witha viscous damper at arbitrary location, and novel frequency shifts are observed. The characterized complexfrequencies presented in this paper can be used for preliminary damping effect evaluation of an adaptivepassive or semi-active or active device for cable vibration control.

Cable with discrete negative stiffness device and viscous damper: passive realization and general characteristics

Chen, Lin,Sun, Limin,Nagarajaiah, Satish Techno-Press 2015 Smart Structures and Systems, An International Jou Vol.15 No.3

Negative stiffness, previously emulated by active or semi-active control for cable vibration mitigation, is realized passively using a self-contained highly compressed spring, the negative stiffness device (NSD).The NSD installed in parallel with a viscous damper (VD) in the vicinity of cable anchorage, enables increment of damper deformation during cable vibrations and hence increases the attainable cable damping. Considering the small cable displacement at the damper location, even with the weakening device, the force provided by the NSD-VD assembly is approximately linear. Complex frequency analysis has thus been conducted to evaluate the damping effect of the assembly on the cable; the displacement-dependent negative stiffness is further accounted by numerical analysis, validating the accuracy of the linear approximation for practical ranges of cable and NSD configurations. The NSD is confirmed to be a practical and cost-effective solution to improve the modal damping of a cable provided by an external damper, especially for super-long cables where the damper location is particularly limited. Moreover, mathematically, a linear negative stiffness and viscous damping assembly has proven capability to represent active or semi-active control for simplified cable vibration analysis as reported in the literature, while in these studies only the assembly located near cable anchorage has been addressed. It is of considerable interest to understand the general characteristics of a cable with the assembly relieving the location restriction, since it is quite practical to have an active controller installed at arbitrary location along the cable span such as by hanging an active tuned mass damper. In this paper the cable frequency variations and damping evolutions with respect to the arbitrary assembly location are then evaluated and compared to those of a taut cable with a viscous damper at arbitrary location, and novel frequency shifts are observed. The characterized complex frequencies presented in this paper can be used for preliminary damping effect evaluation of an adaptive passive or semi-active or active device for cable vibration control.

Isolation, characterization, and identification of proteins interfering with enzyme-linked immunosorbent assay of antibiotics in fish matrix

Wang, Xiudan,Lin, Hong,Cao, Limin,Zheng, Hongwei,Cui, Mengqi,Du, Shuyuan,Sui, Jianxin 한국식품과학회 2016 Food Science and Biotechnology Vol.25 No.5

The interaction between some proteins and immune globulin has been confirmed as an important source of matrix interference with the immunoassay of fishery products, but detailed biochemical properties of these proteins have not been indicated. Two interference-inducing proteins (42 and 36 kD) in flounder were isolated, characterized, and identified. Their influences on the immunoassay of norfloxacin were confirmed by western blotting and enzyme-linked immunosorbent assay. The pI value and pH stability of the two proteins were also investigated. Using LC-MS/MS, the two proteins were identified as fructose-bisphosphate aldolase, and such results were partly verified by the aldolase activity of the 42 and 36 kD isolates. Considering the prevalence of these proteins (as multi-functional aldolase of muscles) in foods, these results would help to further understand the matrix effects in various immunoassays as well as the development of effective techniques to improve the efficiency of immunoassays.

Piezo-activated guided wave propagation and interaction with damage in tubular structures

Ye Lu,Lin Ye,Dong Wang,Limin Zhou,Li Cheng 국제구조공학회 2010 Smart Structures and Systems, An International Jou Vol.6 No.7

This study investigated propagation characteristics of piezo-activated guided waves in an aluminium rectangular-section tube for the purpose of damage identification. Changes in propagating velocity and amplitude of the first wave packet in acquired signals were observed in the frequency range from 50 to 250 kHz. The difference in guided wave propagation between rectangular- and circular-section tubes was examined using finite element simulation, demonstrating a great challenge in interpretation of guided wave signals in rectangular-section tubes. An active sensor network, consisting of nine PZT elements bonded on different surfaces of the tube, was configured to collect the wave signals scattered from through-thickness holes of different diameters. It was found that guided waves were capable of propagating across the sharp tube curvatures while retaining sensitivity to damage, even that not located on the surfaces where actuators/sensors were attached. Signal correlation between the intact and damaged structures was evaluated with the assistance of a concept of digital damage fingerprints (DDFs). The probability of the presence of damage on the unfolded tube surface was thus obtained, by which means the position of damage was identified with good accuracy.

Cable vibration control with internal and external dampers: Theoretical analysis and field test validation

Fangdian Di,Limin Sun,Lin Chen 국제구조공학회 2020 Smart Structures and Systems, An International Jou Vol.26 No.5

For vibration control of stay cables in cable-stayed bridges, viscous dampers are frequently used, and they are regularly installed between the cable and the bridge deck. In practice, neoprene rubber bushings (or of other types) are also widely installed inside the cable guide pipe, mainly for reducing the bending stresses of the cable near its anchorages. Therefore, it is important to understand the effect of the bushings on the performance of the external damper. Besides, for long cables, external dampers installed at a single position near a cable end can no longer provide enough damping due to the sag effect and the limited installation distance. It is thus of interest to improve cable damping by additionally installing dampers inside the guide pipe. This paper hence studies the combined effects of an external damper and an internal damper (which can also model the bushings) on a stay cable. The internal damper is assumed to be a High Damping Rubber (HDR) damper, and the external damper is considered to be a viscous damper with intrinsic stiffness, and the cable sag is also considered. Both the cases when the two dampers are installed close to one cable end and respectively close to the two cable ends are studied. Asymptotic design formulas are derived for both cases considering that the dampers are close to the cable ends. It is shown that when the two dampers are placed close to different cable ends, their combined damping effects are approximately the sum of their separate contributions, regardless of small cable sag and damper intrinsic stiffness. When the two dampers are installed close to the same end, maximum damping that can be achieved by the external damper is generally degraded, regardless of properties of the HDR damper. Field tests on an existing cable-stayed bridge have further validated the influence of the internal damper on the performance of the external damper. The results suggest that the HDR is optimally placed in the guide pipe of the cable-pylon anchorage when installing viscous dampers at one position is insufficient. When an HDR damper or the bushing has to be installed near the external damper, their combined damping effects need to be evaluated using the presented methods.

Isolation, characterization, and identification of proteins interfering with enzyme-linked immunosorbent assay of antibiotics in fish matrix

Xiudan Wang,Hong Lin,Limin Cao,Hongwei Zheng,Mengqi Cui,Shuyuan Du,Jianxin Sui 한국식품과학회 2016 Food Science and Biotechnology Vol.25 No.5

The interaction between some proteins and immune globulin has been confirmed as an important source of matrix interference with the immunoassay of fishery products, but detailed biochemical properties of these proteins have not been indicated. Two interference-inducing proteins (42 and 36 kD) in flounder were isolated, characterized, and identified. Their influences on the immunoassay of norfloxacin were confirmed by western blotting and enzyme-linked immunosorbent assay. The pI value and pH stability of the two proteins were also investigated. Using LC-MS/MS, the two proteins were identified as fructose-bisphosphate aldolase, and such results were partly verified by the aldolase activity of the 42 and 36 kD isolates. Considering the prevalence of these proteins (as multi-functional aldolase of muscles) in foods, these results would help to further understand the matrix effects in various immunoassays as well as the development of effective techniques to improve the efficiency of immunoassays.

Hybrid-Fiber-Reinforced Composite Boards Made of Recycled Aramid Fibers: Preparation and Puncture Properties

Yu-Chun Chuang,Limin Bao,Ching-Wen Lou,Jia-Horng Lin 한국섬유공학회 2019 Fibers and polymers Vol.20 No.2

Protective textiles require massive consumption of fibers and fabrics, which is responsible for diverse highstrength fabric waste. Wrongly arranged disposal of textile waste is equivalent to the waste valuable resource while causing environmental pollutions. Aramid selvages are worthwhile recycling and used in this study. They are scattered into Aramidstaple fibers and mixed with low melting point polyester (LMPET) fibers to form the Aramid matrices employing the nonwoven process. The matrices are added to different combinations to form Aramid composite matrices and hybrid-fiberreinforced composite boards. The process of shearing, crowding, and friction helps improve the mechanical properties of the composite boards according to the evaluations of conducted tests. With the premise of minimum damage to the fibers, this study uses recycled Aramid waste to produce composite boards that have features of high performance and low productioncost. As a test result, the hybrid-fiber-reinforced composite boards with 90 wt% of recycled Aramid fibers have the optimal mechanical property and static puncture resistance.

Piezo-activated guided wave propagation and interaction with damage in tubular structures

Lu, Ye,Ye, Lin,Wang, Dong,Zhou, Limin,Cheng, Li Techno-Press 2010 Smart Structures and Systems, An International Jou Vol.6 No.7

This study investigated propagation characteristics of piezo-activated guided waves in an aluminium rectangular-section tube for the purpose of damage identification. Changes in propagating velocity and amplitude of the first wave packet in acquired signals were observed in the frequency range from 50 to 250 kHz. The difference in guided wave propagation between rectangular- and circular-section tubes was examined using finite element simulation, demonstrating a great challenge in interpretation of guided wave signals in rectangular-section tubes. An active sensor network, consisting of nine PZT elements bonded on different surfaces of the tube, was configured to collect the wave signals scattered from through-thickness holes of different diameters. It was found that guided waves were capable of propagating across the sharp tube curvatures while retaining sensitivity to damage, even that not located on the surfaces where actuators/sensors were attached. Signal correlation between the intact and damaged structures was evaluated with the assistance of a concept of digital damage fingerprints (DDFs). The probability of the presence of damage on the unfolded tube surface was thus obtained, by which means the position of damage was identified with good accuracy.

Influence of Major Urban Construction on Atmospheric Particulates and Emission Reduction Measures

Shunyi Wang,Ping Zhou,Limin Lin,Chuankun Liu,Tao Huang 한국대기환경학회 2018 Asian Journal of Atmospheric Environment (AJAE) Vol.12 No.3

In order to understand the variation of air quality and the concentration of atmospheric particulates in Chengdu Second Ring Road renovation project, this paper starts to investigate the surrounding residents’ opinions on the influenced environment and their daily lives via questionnaires. Then the study numerically simulates the change rule of atmospheric particulates in terms of time and space by using the Gaussian dispersion- deposition model and the compartment model. The optimized scientific scheme is selected by the improved fuzzy analytical hierarchy process (FAHP) to help decision making for the future urban reconstructions. Finally, the reduced emissions of atmospheric particulates are measured when the improvement scheme is provided. According to the study, it can be concluded that the concentration of atmospheric particulates increases rapidly in central Chengdu city during the renovation project, which results in worsening air quality in Chengdu during March 2012 to March 2013. Taking related measures on energy saving and emission reduction can effectively reduce the concentration of atmospheric particulates and promote economic, environmental and social coordination.

All Carbon Dual Ion Batteries

Hu, Zhe,Liu, Qiannan,Zhang, Kai,Zhou, Limin,Li, Lin,Chen, Mingzhe,Tao, Zhanliang,Kang, Yong-Mook,Mai, Liqiang,Chou, Shu-Lei,Chen, Jun,Dou, Shi-Xue American Chemical Society 2018 ACS APPLIED MATERIALS & INTERFACES Vol.10 No.42

<P>Dual ion batteries based on Na<SUP>+</SUP> and PF<SUB>6</SUB><SUP>-</SUP> received considerable attention due to their high operating voltage and the abundant Na resources. Here, cheap and easily obtained graphite that served as a cathode material for dual ion battery delivered a very high average discharge platform (4.52 V vs Na<SUP>+</SUP>/Na) by using sodium hexafluorophosphate in propylene carbonate as electrolyte. Moreover, the all-carbon dual ion batteries with graphite as cathode and hard carbon as anode exhibited an ultrahigh discharge voltage of 4.3 V, and a reversible capacity of 62 mAh·g<SUP>-1</SUP> at 40 mA·g<SUP>-1</SUP>. Phase changes have been investigated in detail through in situ X-ray diffraction and in situ Raman characterizations. The stable structure provides long life cycling performance, and the pseudocapacitance behavior also demonstrates its benefits to the rate capability. Thus, dual ion batteries based on sodium chemistry are very promising to find their applications in future.</P> [FIG OMISSION]</BR>