This paper presents an investigation on the effect of JPEG compression on the similarity between the target image and the background,where the similarity is further used to determine the degree of clutter in the image...This paper presents an investigation on the effect of JPEG compression on the similarity between the target image and the background,where the similarity is further used to determine the degree of clutter in the image.Four new clutter metrics based on image quality assessment are introduced,among which the Haar wavelet-based perceptual similarity index,known as HaarPSI,provides the best target acquisition prediction results.It is shown that the similarity between the target and the background at the boundary between visually lossless and visually lossy compression does not change significantly compared to the case when an uncompressed image is used.In future work,through subjective tests,it is necessary to check whether this presence of compression at the threshold of just noticeable differences will affect the human target acquisition performance.Similarity values are compared with the results of subjective tests of the well-known target Search_2 database,where the degree of agreement between objective and subjective scores,measured through linear correlation,reached a value of 90%.展开更多
The chirp sub-bottom profiler,for its high resolution,easy accessibility and cost-effectiveness,has been widely used in acoustic detection.In this paper,the acoustic impedance and grain size compositions were obtained...The chirp sub-bottom profiler,for its high resolution,easy accessibility and cost-effectiveness,has been widely used in acoustic detection.In this paper,the acoustic impedance and grain size compositions were obtained based on the chirp sub-bottom profiler data collected in the Chukchi Plateau area during the 11th Arctic Expedition of China.The time-domain adaptive search matching algorithm was used and validated on our established theoretical model.The misfit between the inversion result and the theoretical model is less than 0.067%.The grain size was calculated according to the empirical relationship between the acoustic impedance and the grain size of the sediment.The average acoustic impedance of sub-seafloor strata is 2.5026×10^(6) kg(s m^(2))^(-1)and the average grain size(θvalue)of the seafloor surface sediment is 7.1498,indicating the predominant occurrence of very fine silt sediment in the study area.Comparison of the inversion results and the laboratory measurements of nearby borehole samples shows that they are in general agreement.展开更多
Two-axis transportable satellite antennas(TATSAs) have been widely adopted owing to its simple structure and low cost. However, by searching in a wide range, it will take a very long searching time. Under extreme cond...Two-axis transportable satellite antennas(TATSAs) have been widely adopted owing to its simple structure and low cost. However, by searching in a wide range, it will take a very long searching time. Under extreme conditions, it will even fail to work. In this paper, we propose a novel roll compensation(RC) method for the low-cost TATSAs to achieve faster tracking even if when the antenna has no azimuth sensor. By analyzing the influence of roll axis on the system performance, details of the compensation method are derived. Simulation and measurement results indicate that the proposed RC method can effectively reduce the initial searching time for satellite communication. In addition, tracking along with the ellipse path with the RC method provides the highest tracking efficiency.展开更多
The price in an efficient market can adjust to new information instantaneously to eliminate any arbitrage opportunities. Such a phenomenon is not always observed in the real estate market because of its unique charact...The price in an efficient market can adjust to new information instantaneously to eliminate any arbitrage opportunities. Such a phenomenon is not always observed in the real estate market because of its unique characteristics, which include fixed location, heterogeneity and low transaction frequency. Using housing and office market data of some major cities in China, this paper examines the return and risk characteristics in these markets and assesses market efficiency. It finds that a number of instruments, including lagged quarterly and annual excess returns and, to some extent, the measure of the deviation of price from the intrinsic value, predict future returns. Therefore, weak form and semi-strong form efficiency can both be rejected in these real estate markets. These empirical findings suggest that there is slow price adjustment in real estate markets in China, which may be attributed to inefficient information transmission systems and long searching time in the markets.展开更多
Cattle may improve their feeding efficiency by altering their ingestive behaviour in response to changes in the quality of their pastoral environments. To test this hypothesis, an experiment was conducted in a native ...Cattle may improve their feeding efficiency by altering their ingestive behaviour in response to changes in the quality of their pastoral environments. To test this hypothesis, an experiment was conducted in a native pasture that has been managed in continuous stocking at different daily forage allowances （4%, 8%, 12%, and 16% of live weight） for twenty two years thus creating different pastoral environments. For the current experiment, the animals were allocated to their respective experimental units on April 27, 2007. Two experiments were conducted; one was performed at the end of winter （experiment 1）, and the other was undertaken at the end of spring （experiment 2）. Four tester animals were observed per experimental unit （3-5 ha each）. The animals increased their daily grazing time when forage allowance decreased. Most of this increased time was devoted to harvesting, whereas searching was reduced to a few minutes per day. Under conditions of ideal range of forage allowance （between 12% and 14%）, the grazing time was reduced, and the search activity increased. These results suggest that the monitoring of indicators of ingestive behaviour can be used to determine the attributes of forage resources.展开更多
We propose a system for simultaneously presenting numerous pieces of video content with absolute time metadata attached for effectively utilizing increasing number of pieces of video content. The proposed stored forma...We propose a system for simultaneously presenting numerous pieces of video content with absolute time metadata attached for effectively utilizing increasing number of pieces of video content. The proposed stored format used for the system is based on the MMT （MPEG （moving picture experts group） media transport） standardized method, which makes it possible to search by absolute time, and it is a format easy to access by HTTP. We implemented software that can simultaneously present multiple video files according to that format. The constructed system was able to provide service within a feasible processing time.展开更多
With the objective of reducing the flight cost and the amount of polluting emissions released in the atmosphere, a new optimization algorithm considering the climb, cruise and descent phases is presented for the refer...With the objective of reducing the flight cost and the amount of polluting emissions released in the atmosphere, a new optimization algorithm considering the climb, cruise and descent phases is presented for the reference vertical flight trajectory. The selection of the reference vertical navigation speeds and altitudes was solved as a discrete combinatory problem by means of a graphtree passing through nodes using the beam search optimization technique. To achieve a compromise between the execution time and the algorithm＇s ability to find the global optimal solution, a heuristic methodology introducing a parameter called ‘‘optimism coefficient was used in order to estimate the trajectory＇s flight cost at every node. The optimal trajectory cost obtained with the developed algorithm was compared with the cost of the optimal trajectory provided by a commercial flight management system（FMS）. The global optimal solution was validated against an exhaustive search algorithm（ESA）, other than the proposed algorithm. The developed algorithm takes into account weather effects, step climbs during cruise and air traffic management constraints such as constant altitude segments, constant cruise Mach, and a pre-defined reference lateral navigation route. The aircraft fuel burn was computed using a numerical performance model which was created and validated using flight test experimental data.展开更多
文摘This paper presents an investigation on the effect of JPEG compression on the similarity between the target image and the background,where the similarity is further used to determine the degree of clutter in the image.Four new clutter metrics based on image quality assessment are introduced,among which the Haar wavelet-based perceptual similarity index,known as HaarPSI,provides the best target acquisition prediction results.It is shown that the similarity between the target and the background at the boundary between visually lossless and visually lossy compression does not change significantly compared to the case when an uncompressed image is used.In future work,through subjective tests,it is necessary to check whether this presence of compression at the threshold of just noticeable differences will affect the human target acquisition performance.Similarity values are compared with the results of subjective tests of the well-known target Search_2 database,where the degree of agreement between objective and subjective scores,measured through linear correlation,reached a value of 90%.
基金supported by the National Key R&D Program of China (No.2021YFC2801202)the National Natural Science Foundation of China (No.42076224)the Fundamental Research Funds for the Central Universities (No.202262012)。
文摘The chirp sub-bottom profiler,for its high resolution,easy accessibility and cost-effectiveness,has been widely used in acoustic detection.In this paper,the acoustic impedance and grain size compositions were obtained based on the chirp sub-bottom profiler data collected in the Chukchi Plateau area during the 11th Arctic Expedition of China.The time-domain adaptive search matching algorithm was used and validated on our established theoretical model.The misfit between the inversion result and the theoretical model is less than 0.067%.The grain size was calculated according to the empirical relationship between the acoustic impedance and the grain size of the sediment.The average acoustic impedance of sub-seafloor strata is 2.5026×10^(6) kg(s m^(2))^(-1)and the average grain size(θvalue)of the seafloor surface sediment is 7.1498,indicating the predominant occurrence of very fine silt sediment in the study area.Comparison of the inversion results and the laboratory measurements of nearby borehole samples shows that they are in general agreement.
基金jointly sponsored by scientific research foundation NUPTSF(Grant No.NY-214144 and Grant No.NY-215073)NSFC(Grant No.61701260)
文摘Two-axis transportable satellite antennas(TATSAs) have been widely adopted owing to its simple structure and low cost. However, by searching in a wide range, it will take a very long searching time. Under extreme conditions, it will even fail to work. In this paper, we propose a novel roll compensation(RC) method for the low-cost TATSAs to achieve faster tracking even if when the antenna has no azimuth sensor. By analyzing the influence of roll axis on the system performance, details of the compensation method are derived. Simulation and measurement results indicate that the proposed RC method can effectively reduce the initial searching time for satellite communication. In addition, tracking along with the ellipse path with the RC method provides the highest tracking efficiency.
文摘The price in an efficient market can adjust to new information instantaneously to eliminate any arbitrage opportunities. Such a phenomenon is not always observed in the real estate market because of its unique characteristics, which include fixed location, heterogeneity and low transaction frequency. Using housing and office market data of some major cities in China, this paper examines the return and risk characteristics in these markets and assesses market efficiency. It finds that a number of instruments, including lagged quarterly and annual excess returns and, to some extent, the measure of the deviation of price from the intrinsic value, predict future returns. Therefore, weak form and semi-strong form efficiency can both be rejected in these real estate markets. These empirical findings suggest that there is slow price adjustment in real estate markets in China, which may be attributed to inefficient information transmission systems and long searching time in the markets.
文摘Cattle may improve their feeding efficiency by altering their ingestive behaviour in response to changes in the quality of their pastoral environments. To test this hypothesis, an experiment was conducted in a native pasture that has been managed in continuous stocking at different daily forage allowances （4%, 8%, 12%, and 16% of live weight） for twenty two years thus creating different pastoral environments. For the current experiment, the animals were allocated to their respective experimental units on April 27, 2007. Two experiments were conducted; one was performed at the end of winter （experiment 1）, and the other was undertaken at the end of spring （experiment 2）. Four tester animals were observed per experimental unit （3-5 ha each）. The animals increased their daily grazing time when forage allowance decreased. Most of this increased time was devoted to harvesting, whereas searching was reduced to a few minutes per day. Under conditions of ideal range of forage allowance （between 12% and 14%）, the grazing time was reduced, and the search activity increased. These results suggest that the monitoring of indicators of ingestive behaviour can be used to determine the attributes of forage resources.
文摘We propose a system for simultaneously presenting numerous pieces of video content with absolute time metadata attached for effectively utilizing increasing number of pieces of video content. The proposed stored format used for the system is based on the MMT （MPEG （moving picture experts group） media transport） standardized method, which makes it possible to search by absolute time, and it is a format easy to access by HTTP. We implemented software that can simultaneously present multiple video files according to that format. The constructed system was able to provide service within a feasible processing time.
基金the team of the Business-led Network of Centers of Excellence Green Aviation Research & Development Network (GARDN)in particular Mr. Sylvan Cofsky, for the funds received for this project (GARDNⅡ–Project: CMC-21)conducted at The Research Laboratory in Active Controls, Avionics and Aeroservoelasticity (LARCASE) in the framework of the global project ‘‘Optimized Descent and Cruise”
文摘With the objective of reducing the flight cost and the amount of polluting emissions released in the atmosphere, a new optimization algorithm considering the climb, cruise and descent phases is presented for the reference vertical flight trajectory. The selection of the reference vertical navigation speeds and altitudes was solved as a discrete combinatory problem by means of a graphtree passing through nodes using the beam search optimization technique. To achieve a compromise between the execution time and the algorithm＇s ability to find the global optimal solution, a heuristic methodology introducing a parameter called ‘‘optimism coefficient was used in order to estimate the trajectory＇s flight cost at every node. The optimal trajectory cost obtained with the developed algorithm was compared with the cost of the optimal trajectory provided by a commercial flight management system（FMS）. The global optimal solution was validated against an exhaustive search algorithm（ESA）, other than the proposed algorithm. The developed algorithm takes into account weather effects, step climbs during cruise and air traffic management constraints such as constant altitude segments, constant cruise Mach, and a pre-defined reference lateral navigation route. The aircraft fuel burn was computed using a numerical performance model which was created and validated using flight test experimental data.
