Principle on temperature response to the stress-strain variation is fundamental to the relationship between thermal radiation variation and stress-strain field. Current research indicates that temperature has a sensit...Principle on temperature response to the stress-strain variation is fundamental to the relationship between thermal radiation variation and stress-strain field. Current research indicates that temperature has a sensitive response to rock deformation under the condition of normal temperature background. However, the basic physical relationship between deformation and temperature variation is not clear and need to be investigated further. In this paper, principle on temperature response to stress-strain variation is studied in detail, based on thermodynamics, elastic strain theory, and experiments on both ideal material and rock. In the stage of elastic deformation, results indicate that: 1) temperature increment is positively correlated with volume strain variation. Temperature rises with hydrostatic pressure increase. In other words, temperature rises when the specimen is under the compressive state whereas temperature drops under the tensile state. 2) Pure shear deformation does not contribute to tempera- ture variation. Namely, shape change of specimen does not produce temperature variation. However, there exist the relative tensile area and the compressive one in the specimen under the state of pure shear. Temperature drops within the relative tensile area while temperature rises within the compressive areas during the process of loading.展开更多
Target detection is one of the key technology of precision chemical application.Previously the digital coding modulation technique was commonly used to emit and receive the optical signal in the target detection syste...Target detection is one of the key technology of precision chemical application.Previously the digital coding modulation technique was commonly used to emit and receive the optical signal in the target detection systems previously in China.It was difficult to adjust the output power,and the anti-interference ability was weak in these systems.In order to resolve these problems,the target detection method based on analog sine-wave modulation was studied.The spectral detecting system was set up in the aspects of working principle,electric circuit,and optical path.Lab testing was performed.The results showed that the reflected signal from the target varied inversely with detection distances.It indicated that it was feasible to establish the target detection system using analog sine-wave modulation technology.Furthermore,quantitative measurement of the reflected optical signal for near-infrared and visible light could be achieved by using this system.The research laid the foundation for the future development of the corresponding instrument.展开更多
Contrast is the differential luminance between one object and another.Contrast sensitivity(CS)quantifies the ability to detect this difference:estimating contrast threshold provides information about the quality of vi...Contrast is the differential luminance between one object and another.Contrast sensitivity(CS)quantifies the ability to detect this difference:estimating contrast threshold provides information about the quality of vision and helps diagnose and monitor eye diseases.High contrast visual acuity assessment is traditionally performed in the eye care practice,whereas the estimate of the discrimination of low contrast targets,an important complementary task for the perception of details,is far less employed.An example is driving when the contrast between vehicles,obstacles,pedestrians,and the background is reduced by fog.Many conditions can selectively degrade CS,while visual acuity remains intact.In addition to spatial CS,“temporal”CS is defined as the ability to discriminate luminance differences in the temporal domain,i.e.,to discriminate information that reaches the visual cortex as a function of time.Likewise,temporal sensitivity of the visual system can be investigated in terms of critical fusion frequency(CFF),an indicator of the integrity of the magnocellular system that is responsible for the perception of transient stimulations.As a matter of fact,temporal resolution can be abnormal in neuro-ophthalmological clinical conditions.This paper aims at considering CS and its application to the clinical practice.展开更多
基金Supported by Basic Research Funds from Institute of Geology,China Earthquake Administration (Grant No. DF-IGCEA-0607-1-5)National Natural Science Founda-tion of China (Grant Nos. 40572125, 90202018) Special Funds for Social Public of Ministry of Science and Technology (Grant No. 2004DIB3J129)
文摘Principle on temperature response to the stress-strain variation is fundamental to the relationship between thermal radiation variation and stress-strain field. Current research indicates that temperature has a sensitive response to rock deformation under the condition of normal temperature background. However, the basic physical relationship between deformation and temperature variation is not clear and need to be investigated further. In this paper, principle on temperature response to stress-strain variation is studied in detail, based on thermodynamics, elastic strain theory, and experiments on both ideal material and rock. In the stage of elastic deformation, results indicate that: 1) temperature increment is positively correlated with volume strain variation. Temperature rises with hydrostatic pressure increase. In other words, temperature rises when the specimen is under the compressive state whereas temperature drops under the tensile state. 2) Pure shear deformation does not contribute to tempera- ture variation. Namely, shape change of specimen does not produce temperature variation. However, there exist the relative tensile area and the compressive one in the specimen under the state of pure shear. Temperature drops within the relative tensile area while temperature rises within the compressive areas during the process of loading.
基金Supported by the National“863”Project of China(2010AA10A301)National Technology Support Project for the 12th Five-year Plan(2011BAD20B07)
文摘Target detection is one of the key technology of precision chemical application.Previously the digital coding modulation technique was commonly used to emit and receive the optical signal in the target detection systems previously in China.It was difficult to adjust the output power,and the anti-interference ability was weak in these systems.In order to resolve these problems,the target detection method based on analog sine-wave modulation was studied.The spectral detecting system was set up in the aspects of working principle,electric circuit,and optical path.Lab testing was performed.The results showed that the reflected signal from the target varied inversely with detection distances.It indicated that it was feasible to establish the target detection system using analog sine-wave modulation technology.Furthermore,quantitative measurement of the reflected optical signal for near-infrared and visible light could be achieved by using this system.The research laid the foundation for the future development of the corresponding instrument.
文摘Contrast is the differential luminance between one object and another.Contrast sensitivity(CS)quantifies the ability to detect this difference:estimating contrast threshold provides information about the quality of vision and helps diagnose and monitor eye diseases.High contrast visual acuity assessment is traditionally performed in the eye care practice,whereas the estimate of the discrimination of low contrast targets,an important complementary task for the perception of details,is far less employed.An example is driving when the contrast between vehicles,obstacles,pedestrians,and the background is reduced by fog.Many conditions can selectively degrade CS,while visual acuity remains intact.In addition to spatial CS,“temporal”CS is defined as the ability to discriminate luminance differences in the temporal domain,i.e.,to discriminate information that reaches the visual cortex as a function of time.Likewise,temporal sensitivity of the visual system can be investigated in terms of critical fusion frequency(CFF),an indicator of the integrity of the magnocellular system that is responsible for the perception of transient stimulations.As a matter of fact,temporal resolution can be abnormal in neuro-ophthalmological clinical conditions.This paper aims at considering CS and its application to the clinical practice.
