A new type of pit supporting structure, which was tested and verified using the sensor monitoring technology, was presented. The new supporting structure is assembled by prefabricated steel structural units. The adjac...A new type of pit supporting structure, which was tested and verified using the sensor monitoring technology, was presented. The new supporting structure is assembled by prefabricated steel structural units. The adjacent steel structural units are jointed with fasteners, and each steel structural unit has a certain radian and is welded by two steel tubes and one piece of steel disc. In order to test and verify the reliability of the new supporting structure, the field tests are designed. The main monitoring programs include the hoop stress of supporting structure, lateral earth pressure, and soil deformation. The monitoring data of the field tests show that the new supporting structure is convenient, reliable and safe.展开更多
For the evaluation of construction quality and the verification of the design of water conservancy and hydropower engineering projects, and especially for the control of dam safety operation behavior, safety monitorin...For the evaluation of construction quality and the verification of the design of water conservancy and hydropower engineering projects, and especially for the control of dam safety operation behavior, safety monitoring sensors are employed in a majority of engineering projects. These sensors are used to monitor the project during the dam construction and operation periods, and play an important role in reservoir safety operation and producing benefits. With the changing of operating environments and run-time of projects, there are some factors affecting the operation and management of projects, such as a certain amount of damaged sensors and instability of the measured data. Therefore, it is urgent to evaluate existing safety monitoring sensors in water conservancy and hydropower engineering projects. However, there are neither standards nor evaluation guidelines at present. Based on engineering practice, this study examined some key techniques for the evaluation of safety monitoring sensors, including the evaluation process of the safety monitoring system, on-site detection methods of two typical pieces of equipment, the differential resistor sensor and vibrating wire sensor, the on-site detection methods of communication cable faults, and a validity test of the sensor measured data. These key techniques were applied in the Xiaolangdi Water Control Project and Xiaoxi Hydropower Project. The results show that the measured data of a majority of sensors are reliable and reasonable, and can reasonably reflect the structural change behavior in the project operating process, indicating that the availabilities of the safety monitoring sensors of the two projects are high展开更多
In order to monitor the basic mechanical properties and interior damage of concrete structures,the piezoelectric actuator/sensor based wave propagation method was investigated experimentally in the laboratory using a ...In order to monitor the basic mechanical properties and interior damage of concrete structures,the piezoelectric actuator/sensor based wave propagation method was investigated experimentally in the laboratory using a specifically designed test setup.The energy attenuation of stress waves was measured by the relative index between the output voltage of sensors and the excitation voltage at the actuator.Based on the experimental results of concrete cube and cylinder specimens,the effect of excitation frequencies,excitation amplitude,wave propagation paths and the curing age on the output signals of sensors are evaluated.The results show that the relative voltage attenuation coefficient RVAC is an effective indicator for measuring the attenuation of stress waves through the interior of concrete.展开更多
Shape memory alloy （SMA） materials possess completely superelasticity or pseudoelasticity above the austenite finish temperature and many unique mechanical, thermal, thermal-mechanical and electrical properties comp...Shape memory alloy （SMA） materials possess completely superelasticity or pseudoelasticity above the austenite finish temperature and many unique mechanical, thermal, thermal-mechanical and electrical properties compared with other conventional materials. Many studies have reported that the superelastic and hysteresis properties of the SMA materials can absorb energies coming from external excitations or sudden impacts. In addition, due to the special electrical properties of NiTi superelastic wires, they can also be used as strain-sensing element to monitor structural health conditions. Composite laminated specimens embedded with SMA wire sensors are fabricated and detailed testing system is designed such as multi-parameters measuring for impact and weak signal processing for SMA sensor. Low velocity impact test shows that SMA wire sensors embedded in fiber-reinforced plastic （FRP） laminate can be well used to monitor impact responses, such as the location of impact damage, impact degree, and strain distribution. Experimental results and theoretical predictions reveal almost the same. Comparing with other method, a simple, economic and reliable technique method monitoring important engineering structures on line is provided.展开更多
High-sensitivity monitoring solutions are crucial for early warning systems of earth structures. In this paper, we discuss the design and implementation of such systems for natural and engineered slopes using two case...High-sensitivity monitoring solutions are crucial for early warning systems of earth structures. In this paper, we discuss the design and implementation of such systems for natural and engineered slopes using two case studies. At the Gradenbach Observatory, one key element of the monitoring system is a large fiber optic strain rosette embedded in the slope. We demonstrate that the strain rosette can depict landslide deformations much earlier than geodetic sensors like GPS or total stations and is therefore well suitable for an early warning system. In a second application we report the construction of a reinforced earth structure using geogrids. A distributed fiber optic measurement system was installed to measure the current operating grade of the geogrids within the earth structure. About 2 km of Brillouin sensing cables were installed in the project area. It is demonstrated that the developed monitoring system is well suited for assessing the current state of health of reinforced earth structures.展开更多
We report a fiber Bragg grating（FBG）-based sensor for the simultaneous measurement of a train bearing’s vibration and temperature. A pre-stretched optical fiber with an FBG and a mass is designed for axial vibratio...We report a fiber Bragg grating（FBG）-based sensor for the simultaneous measurement of a train bearing’s vibration and temperature. A pre-stretched optical fiber with an FBG and a mass is designed for axial vibration sensing. Another multiplexed FBG is embedded in a selected copper-based alloy with a high thermal expansion to detect temperature. Experiments show that the sensor possesses a high resonant frequency of 970 Hz, an acceleration sensitivity of 27.28 pm/g, and a high temperature sensitivity of 35.165 pm/℃. A resonant excitation test is also carried out that demonstrates the robustness and reliability of the sensor.展开更多
The principles for lifecycle safety guarantee of engineering structures areproposed, and the conception is developed for developing the safety guarantee system by integratingthe monitoring system, analysis system and ...The principles for lifecycle safety guarantee of engineering structures areproposed, and the conception is developed for developing the safety guarantee system by integratingthe monitoring system, analysis system and maintenance system together on the basis of multi-sensor,distribution-measurement, data fusion and digital-signal-processor (DSP) technologies as well asthree-dimensional (3D) fatigue fracture unified theory. As all the systems should work in situs andin real-time, micromation and integration are important. Damage detectability is introduced toclarify the relationship of life prediction and healthy monitoring or faulty diagnosis. The researchwork to realize the lifecycle safety guarantee system is summarized and perspectives for futureefforts are outlined.展开更多
The fields of regenerative medicine and tissue engineering offer new therapeutic options to restore,maintain or improve tissue function following disease or injury.To maximize the biological function of a tissue-engin...The fields of regenerative medicine and tissue engineering offer new therapeutic options to restore,maintain or improve tissue function following disease or injury.To maximize the biological function of a tissue-engineered clinical product,specific conditions must be maintained within a bioreactor to allow the maturation of the product in preparation for implantation.Specifically,the bioreactor should be designed to mimic the mechanical,electrochemical and biochemical environment that the product will be exposed to in vivo.Real-time monitoring of the functional capacity of tissue-engineered products during manufacturing is a critical component of the quality management process.The present review provides a brief overview of bioreactor engineering considerations.In addition,strategies for bioreactor automation,in-line product monitoring and quality assurance are discussed.展开更多
During surgery,a heartbeat doesn’t just tell whether a person is dead or alive-it can warn of big problems that come up quite suddenly.Keeping watch for subtle irregularities in the heart’s electric activity can hel...During surgery,a heartbeat doesn’t just tell whether a person is dead or alive-it can warn of big problems that come up quite suddenly.Keeping watch for subtle irregularities in the heart’s electric activity can help save a patient’s life.But today’s technology can’t give as much detail as doctors展开更多
The yield monitors use a constant delay time to match the grain flow with location.Therefore,mixing and smoothing effects on the grain flow are neglected.Although constant time delay compensates for time mismatch,actu...The yield monitors use a constant delay time to match the grain flow with location.Therefore,mixing and smoothing effects on the grain flow are neglected.Although constant time delay compensates for time mismatch,actual grain flow at a combine harvester head is not equal to the grain flow measured by a sensor due to the dynamics effects.In order to eliminate the dynamics effects,a new method for estimating actual grain flow,called proportional distribution(PD),is proposed.This method assumes that actual grain flow is directly proportional to the feedrate.Based on this assumption,the actual grain flow results from redistributing accumulated grain mass over a certain time according to the profile of the feedrate.The PD can avoid the dynamics effects because the feedrate is measured at a combine harvester’s head.Compared with constant time delay,the proposed method can effectively estimate actual grain flow and be applied to improve the accuracy of yield maps.展开更多
基金Project(41202220) supported by the National Natural Science Foundation of ChinaProject(20120022120003) supported by the Research Fund for the Doctoral Program of Higher Education, China+1 种基金Project(2-9-2012-65) supported by the Fundamental Research Funds for the Central Universities, ChinaProject(2013006) supported by the Research Fund for Key Laboratory on Deep GeoDrilling Technology, Ministry of Land and Resources, China
文摘A new type of pit supporting structure, which was tested and verified using the sensor monitoring technology, was presented. The new supporting structure is assembled by prefabricated steel structural units. The adjacent steel structural units are jointed with fasteners, and each steel structural unit has a certain radian and is welded by two steel tubes and one piece of steel disc. In order to test and verify the reliability of the new supporting structure, the field tests are designed. The main monitoring programs include the hoop stress of supporting structure, lateral earth pressure, and soil deformation. The monitoring data of the field tests show that the new supporting structure is convenient, reliable and safe.
基金supported by the National Natural Science Foundation of China(Grants No.51179108and50909066)the Key Research Foundation of Nanjing Hydraulic Research Institute(Grant No.Y711007)
文摘For the evaluation of construction quality and the verification of the design of water conservancy and hydropower engineering projects, and especially for the control of dam safety operation behavior, safety monitoring sensors are employed in a majority of engineering projects. These sensors are used to monitor the project during the dam construction and operation periods, and play an important role in reservoir safety operation and producing benefits. With the changing of operating environments and run-time of projects, there are some factors affecting the operation and management of projects, such as a certain amount of damaged sensors and instability of the measured data. Therefore, it is urgent to evaluate existing safety monitoring sensors in water conservancy and hydropower engineering projects. However, there are neither standards nor evaluation guidelines at present. Based on engineering practice, this study examined some key techniques for the evaluation of safety monitoring sensors, including the evaluation process of the safety monitoring system, on-site detection methods of two typical pieces of equipment, the differential resistor sensor and vibrating wire sensor, the on-site detection methods of communication cable faults, and a validity test of the sensor measured data. These key techniques were applied in the Xiaolangdi Water Control Project and Xiaoxi Hydropower Project. The results show that the measured data of a majority of sensors are reliable and reasonable, and can reasonably reflect the structural change behavior in the project operating process, indicating that the availabilities of the safety monitoring sensors of the two projects are high
基金Funded by the National Natural Science Foundation of China (No.50708065)the National High-tech R&D Program(863 Program )(No.2007-AA-11-Z-113)the Key Projects in the Science and Technology Pillar Program of Tianjin(No.11ZCKFSF00300)
文摘In order to monitor the basic mechanical properties and interior damage of concrete structures,the piezoelectric actuator/sensor based wave propagation method was investigated experimentally in the laboratory using a specifically designed test setup.The energy attenuation of stress waves was measured by the relative index between the output voltage of sensors and the excitation voltage at the actuator.Based on the experimental results of concrete cube and cylinder specimens,the effect of excitation frequencies,excitation amplitude,wave propagation paths and the curing age on the output signals of sensors are evaluated.The results show that the relative voltage attenuation coefficient RVAC is an effective indicator for measuring the attenuation of stress waves through the interior of concrete.
基金This project is supported by Provincial Natural Science Foundation of Jiangsu, China(No.BJ99034)Foundation of Nantong City Science and Technology Leader, China(No.2004033)
文摘Shape memory alloy （SMA） materials possess completely superelasticity or pseudoelasticity above the austenite finish temperature and many unique mechanical, thermal, thermal-mechanical and electrical properties compared with other conventional materials. Many studies have reported that the superelastic and hysteresis properties of the SMA materials can absorb energies coming from external excitations or sudden impacts. In addition, due to the special electrical properties of NiTi superelastic wires, they can also be used as strain-sensing element to monitor structural health conditions. Composite laminated specimens embedded with SMA wire sensors are fabricated and detailed testing system is designed such as multi-parameters measuring for impact and weak signal processing for SMA sensor. Low velocity impact test shows that SMA wire sensors embedded in fiber-reinforced plastic （FRP） laminate can be well used to monitor impact responses, such as the location of impact damage, impact degree, and strain distribution. Experimental results and theoretical predictions reveal almost the same. Comparing with other method, a simple, economic and reliable technique method monitoring important engineering structures on line is provided.
基金the Austrian Academy of Sciences(OeAW)for funding the landslide monitoring project for several yearsthe Austrian Federal Railways(OBB)for the funding of the geogrid monitoring project,especially the participating departments of OBB-Infrastruktur AG:Tunneling,Surveying and Data Management,Research and Development
文摘High-sensitivity monitoring solutions are crucial for early warning systems of earth structures. In this paper, we discuss the design and implementation of such systems for natural and engineered slopes using two case studies. At the Gradenbach Observatory, one key element of the monitoring system is a large fiber optic strain rosette embedded in the slope. We demonstrate that the strain rosette can depict landslide deformations much earlier than geodetic sensors like GPS or total stations and is therefore well suitable for an early warning system. In a second application we report the construction of a reinforced earth structure using geogrids. A distributed fiber optic measurement system was installed to measure the current operating grade of the geogrids within the earth structure. About 2 km of Brillouin sensing cables were installed in the project area. It is demonstrated that the developed monitoring system is well suited for assessing the current state of health of reinforced earth structures.
基金supported in part by the National Natural Science Foundation of China(Nos.51605348 and 51605344)in part by the Natural Science Foundation of the Hubei Province(No.2016CFB116)in part by the Open Research Fund of the Hubei Digital Manufacturing Key Laboratory(No.SZ1801)
文摘We report a fiber Bragg grating（FBG）-based sensor for the simultaneous measurement of a train bearing’s vibration and temperature. A pre-stretched optical fiber with an FBG and a mass is designed for axial vibration sensing. Another multiplexed FBG is embedded in a selected copper-based alloy with a high thermal expansion to detect temperature. Experiments show that the sensor possesses a high resonant frequency of 970 Hz, an acceleration sensitivity of 27.28 pm/g, and a high temperature sensitivity of 35.165 pm/℃. A resonant excitation test is also carried out that demonstrates the robustness and reliability of the sensor.
基金This project is supported by National Natural Science Foundation of China (No.50275073)Space Science Foundation of China (No.03B52011).
文摘The principles for lifecycle safety guarantee of engineering structures areproposed, and the conception is developed for developing the safety guarantee system by integratingthe monitoring system, analysis system and maintenance system together on the basis of multi-sensor,distribution-measurement, data fusion and digital-signal-processor (DSP) technologies as well asthree-dimensional (3D) fatigue fracture unified theory. As all the systems should work in situs andin real-time, micromation and integration are important. Damage detectability is introduced toclarify the relationship of life prediction and healthy monitoring or faulty diagnosis. The researchwork to realize the lifecycle safety guarantee system is summarized and perspectives for futureefforts are outlined.
基金US Army Medical Research and Development Command through the Medical Technology Enterprise Consortium under Contract#W81XWH-15-9-0001.
文摘The fields of regenerative medicine and tissue engineering offer new therapeutic options to restore,maintain or improve tissue function following disease or injury.To maximize the biological function of a tissue-engineered clinical product,specific conditions must be maintained within a bioreactor to allow the maturation of the product in preparation for implantation.Specifically,the bioreactor should be designed to mimic the mechanical,electrochemical and biochemical environment that the product will be exposed to in vivo.Real-time monitoring of the functional capacity of tissue-engineered products during manufacturing is a critical component of the quality management process.The present review provides a brief overview of bioreactor engineering considerations.In addition,strategies for bioreactor automation,in-line product monitoring and quality assurance are discussed.
文摘During surgery,a heartbeat doesn’t just tell whether a person is dead or alive-it can warn of big problems that come up quite suddenly.Keeping watch for subtle irregularities in the heart’s electric activity can help save a patient’s life.But today’s technology can’t give as much detail as doctors
基金supported by Nature Science Foundation of Liaoning Province,China(No.2015020128)。
文摘The yield monitors use a constant delay time to match the grain flow with location.Therefore,mixing and smoothing effects on the grain flow are neglected.Although constant time delay compensates for time mismatch,actual grain flow at a combine harvester head is not equal to the grain flow measured by a sensor due to the dynamics effects.In order to eliminate the dynamics effects,a new method for estimating actual grain flow,called proportional distribution(PD),is proposed.This method assumes that actual grain flow is directly proportional to the feedrate.Based on this assumption,the actual grain flow results from redistributing accumulated grain mass over a certain time according to the profile of the feedrate.The PD can avoid the dynamics effects because the feedrate is measured at a combine harvester’s head.Compared with constant time delay,the proposed method can effectively estimate actual grain flow and be applied to improve the accuracy of yield maps.
