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This essay situates measurement in its larger context. Relying on some basic concepts from formal logic, the essay shows that current conceptions of "measurement issues" comprise just a subset of the larger universe of issues conc...
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This essay situates measurement in its larger context. Relying on some basic concepts from formal logic, the essay shows that current conceptions of "measurement issues" comprise just a subset of the larger universe of issues concerning measurement. New issues, going beyond the current conceptions, are identified such as the need for attention also to be given to the measurement of relationships, not just the measurement of constructs. Our analysis of these issues has several ramifications for empirical research. In particular, it highlights the cascading or cumulative impacts that errors in measures and measurement have in successive building blocks of empirical scientific reasoning. Overall, the essay demonstrates the need for more emphasis to be placed on fundamental issues involved in measuring and measurement and provides a framework that can help researchers and reviewers consider and evaluate these efforts. Our arguments apply to all empirical research, whether quantitative or qualitative, confirmatory, or exploratory.
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The sound velocity in ice is of great significance to the acoustic propagation characteristics of ocean channels under ice cover and the acoustic characteristics of underwater targets. Freshwater ice has a uniform crystal structur...
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The sound velocity in ice is of great significance to the acoustic propagation characteristics of ocean channels under ice cover and the acoustic characteristics of underwater targets. Freshwater ice has a uniform crystal structure under normal conditions. The freezing process of sea ice is more complicated compared to fresh water ice. The sea ice contains a lot of bubbles, brine, solid particles and other impurities. Due to the large difference in the structure and composition of ice in different states, it is very different from the common sound transmission media in the past. Therefore, in order to accurately describe the acoustic propagation characteristics of the ocean channel under the ice cover, it is necessary to measure the longitudinal sound velocity in the ice accurately. A direct method for measuring the speed of longitudinal waves in ice is studied in this paper. The propagation time of high-frequency pulses in the ice is used in this research to determine the speed of longitudinal waves. For the same piece of ice, the method of averaging multiple measurements was used to reduce the measurement error. Six tests were performed on typical ice with different structural characteristics. The six tests were the fresh water in Songhua Lake area of Jilin Province in 2019, the high mud content sea ice in the coastal area of Bohai Bay in 2020, the low mud content sea ice in Liaodong Bay area in 2021, the artificial quick-frozen sea ice and fresh water ice at -20°C, and the summer Arctic sea ice obtained in the eleventh Arctic scientific survey in 2020. The sound velocity of longitudinal waves in ice was measured at 12kHz, 25kHz, 50kHz, 75kHz, and 100kHz. The acoustic properties of ice are determined by its own state. The measurement results have certain fluctuations, because the test results were closely related to the sample test environment and test process. The measurement results of longitudinal wave sound velocity were described by the measurement mean value and standard deviation in order to scientifically express the longitudinal wave sound velocity in ice. The test results showed that the longitudinal sound velocity in high mud content sea ice was about 3360±162m/s, 3270±78m/s in low mud content sea ice, 3769±54m/s in artificial sea ice, 3772±57m/s in lake ice, 3729±23m/s in artificial fresh water ice, and 3893±86m/s in Arctic ice. Under the same measured temperature, the compression wave sound velocities in most ice media are stable at 3750 m/s. The research methods and results in this paper provide references for related research on the acoustic properties of ice media, the acoustic propagation characteristics under ice cover and target acoustic characteristics in ice area.
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摘要 :
The sound velocity in ice is of great significance to the acoustic propagation characteristics of ocean channels under ice cover and the acoustic characteristics of underwater targets. Freshwater ice has a uniform crystal structur...
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The sound velocity in ice is of great significance to the acoustic propagation characteristics of ocean channels under ice cover and the acoustic characteristics of underwater targets. Freshwater ice has a uniform crystal structure under normal conditions. The freezing process of sea ice is more complicated compared to fresh water ice. The sea ice contains a lot of bubbles, brine, solid particles and other impurities. Due to the large difference in the structure and composition of ice in different states, it is very different from the common sound transmission media in the past. Therefore, in order to accurately describe the acoustic propagation characteristics of the ocean channel under the ice cover, it is necessary to measure the longitudinal sound velocity in the ice accurately. A direct method for measuring the speed of longitudinal waves in ice is studied in this paper. The propagation time of high-frequency pulses in the ice is used in this research to determine the speed of longitudinal waves. For the same piece of ice, the method of averaging multiple measurements was used to reduce the measurement error. Six tests were performed on typical ice with different structural characteristics. The six tests were the fresh water in Songhua Lake area of Jilin Province in 2019, the high mud content sea ice in the coastal area of Bohai Bay in 2020, the low mud content sea ice in Liaodong Bay area in 2021, the artificial quick-frozen sea ice and fresh water ice at -20°C, and the summer Arctic sea ice obtained in the eleventh Arctic scientific survey in 2020. The sound velocity of longitudinal waves in ice was measured at 12kHz, 25kHz, 50kHz, 75kHz, and 100kHz. The acoustic properties of ice are determined by its own state. The measurement results have certain fluctuations, because the test results were closely related to the sample test environment and test process. The measurement results of longitudinal wave sound velocity were described by the measurement mean value and standard deviation in order to scientifically express the longitudinal wave sound velocity in ice. The test results showed that the longitudinal sound velocity in high mud content sea ice was about 3360±162m/s, 3270±78m/s in low mud content sea ice, 3769±54m/s in artificial sea ice, 3772±57m/s in lake ice, 3729±23m/s in artificial fresh water ice, and 3893±86m/s in Arctic ice. Under the same measured temperature, the compression wave sound velocities in most ice media are stable at 3750 m/s. The research methods and results in this paper provide references for related research on the acoustic properties of ice media, the acoustic propagation characteristics under ice cover and target acoustic characteristics in ice area.
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Cosmic rays are high energy particles travelling at near the speed of light. Unlike electromagnetic waves, they are subjected to the influence of magnetic field. Being small in size, some of these particles can penetrate through c...
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Cosmic rays are high energy particles travelling at near the speed of light. Unlike electromagnetic waves, they are subjected to the influence of magnetic field. Being small in size, some of these particles can penetrate through certain low-density metals with no ionization at all. Some of the cosmic particles will bombard with the atoms in the metal, forming positive ions. Aluminum and silver are low-density metals having surface plasmon resonant frequencies right at the ultraviolet band. If one of these metals is chosen to capture cosmic energy, a large portion of the cosmic particles can pass through the metal without doing any work. This means capturing a cosmic energy into a DC will not be efficient if aluminum or silver are used to capture cosmic energy. In this paper, we propose a novel cosmic energy receiver which can cost-effectively capture cosmic energy into a DC without running this problem. To prove its feasibility, experimental prototypes have been built and their load voltages have been measured in the absence of any sunlight.
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摘要 :
Cosmic rays are high energy particles travelling at near the speed of light. Unlike electromagnetic waves, they are subjected to the influence of magnetic field. Being small in size, some of these particles can penetrate through c...
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Cosmic rays are high energy particles travelling at near the speed of light. Unlike electromagnetic waves, they are subjected to the influence of magnetic field. Being small in size, some of these particles can penetrate through certain low-density metals with no ionization at all. Some of the cosmic particles will bombard with the atoms in the metal, forming positive ions. Aluminum and silver are low-density metals having surface plasmon resonant frequencies right at the ultraviolet band. If one of these metals is chosen to capture cosmic energy, a large portion of the cosmic particles can pass through the metal without doing any work. This means capturing a cosmic energy into a DC will not be efficient if aluminum or silver are used to capture cosmic energy. In this paper, we propose a novel cosmic energy receiver which can cost-effectively capture cosmic energy into a DC without running this problem. To prove its feasibility, experimental prototypes have been built and their load voltages have been measured in the absence of any sunlight.
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This VSC-HVDC (Voltage Sourced Converter) has been widely applied all over the world owing to its unique advantages. Converter valve is the key equipment of VSCs, its losses are significant to the economically operation of VSC sta...
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This VSC-HVDC (Voltage Sourced Converter) has been widely applied all over the world owing to its unique advantages. Converter valve is the key equipment of VSCs, its losses are significant to the economically operation of VSC stations. Analysis and accurate measurement of the losses can make great contribution to efficiency optimization, devices selection and thermal design, etc. The paper investigated the losses measurement technology of power electronics equipment and surveyed the academic research at home and abroad of the double pulse method, electric method and thermal method for losses measurement. It came up with three test schemes for measuring losses of VSC sub-modules respectively, the schemes include measuring method, test circuit design, equipment selection, software platform and its control method, test procedure, uncertainty and loss estimation method. In the physical test platform, tests based on three schemes are carried out, the uncertainty of tests results is analyzed. This paper provides reference for measuring losses of VSC sub-modules in practical projects.
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This VSC-HVDC (Voltage Sourced Converter) has been widely applied all over the world owing to its unique advantages. Converter valve is the key equipment of VSCs, its losses are significant to the economically operation of VSC sta...
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This VSC-HVDC (Voltage Sourced Converter) has been widely applied all over the world owing to its unique advantages. Converter valve is the key equipment of VSCs, its losses are significant to the economically operation of VSC stations. Analysis and accurate measurement of the losses can make great contribution to efficiency optimization, devices selection and thermal design, etc. The paper investigated the losses measurement technology of power electronics equipment and surveyed the academic research at home and abroad of the double pulse method, electric method and thermal method for losses measurement. It came up with three test schemes for measuring losses of VSC sub-modules respectively, the schemes include measuring method, test circuit design, equipment selection, software platform and its control method, test procedure, uncertainty and loss estimation method. In the physical test platform, tests based on three schemes are carried out, the uncertainty of tests results is analyzed. This paper provides reference for measuring losses of VSC sub-modules in practical projects.
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To provide sufficient flexibility for reliable software functioning quantitative assessment of cohesion and coupling of modules of software algorithms is needed. The paper estimates possibility of formation of mathematical constru...
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To provide sufficient flexibility for reliable software functioning quantitative assessment of cohesion and coupling of modules of software algorithms is needed. The paper estimates possibility of formation of mathematical constructs for quantitative determination of cohesion and coupling of modules, which are based on similarity, difference, and inclusion algorithms of the modules of software products, coordinated with meaningful situations. They are considered for multiple, descriptive, probabilistic, and mathematical formalization of information objects. Application the algorithm-specified measure defines new properties that modify the algorithm under current conditions. The study of the properties of the Kullback - Leibler distance showed that it cannot be used as a measure of integration because of its asymmetry, but is an information measure of inclusions, which can be used to form the information integration measure that has the property of symmetry. Examples of the application of the results are provided.
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In this study, impedance measurement is implemented using the vector current-voltage method. The zero-crossing method is used to separate the real and the imaginary parts of the impedance vector, and the phase difference informati...
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In this study, impedance measurement is implemented using the vector current-voltage method. The zero-crossing method is used to separate the real and the imaginary parts of the impedance vector, and the phase difference information is acquired using the high-speed data acquisition method. However, the limitation of the resolution of the phase difference often prevents the improvement of the accuracy of the impedance measurement. Therefore, in this paper, we propose a method for high-resolution phase measurement based on high-speed acquisition technology. Using the gigabit transceiver integrated in the XILINX K-7 Series field-programmable gate arrays, we achieve a sampling rate of 6 Gbps or higher, thereby improving the resolution of the phase difference time and considerably improving the accuracy of the impedance measurement.
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摘要 :
In this study, impedance measurement is implemented using the vector current-voltage method. The zero-crossing method is used to separate the real and the imaginary parts of the impedance vector, and the phase difference informati...
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In this study, impedance measurement is implemented using the vector current-voltage method. The zero-crossing method is used to separate the real and the imaginary parts of the impedance vector, and the phase difference information is acquired using the high-speed data acquisition method. However, the limitation of the resolution of the phase difference often prevents the improvement of the accuracy of the impedance measurement. Therefore, in this paper, we propose a method for high-resolution phase measurement based on high-speed acquisition technology. Using the gigabit transceiver integrated in the XILINX K-7 Series field-programmable gate arrays, we achieve a sampling rate of 6 Gbps or higher, thereby improving the resolution of the phase difference time and considerably improving the accuracy of the impedance measurement.
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