The efficiency parameters are studied in this paper for evaluating the compression quality of the inlets with different compression degrees and assessing different design methods.Selfconsistency is proposed for the ef...The efficiency parameters are studied in this paper for evaluating the compression quality of the inlets with different compression degrees and assessing different design methods.Selfconsistency is proposed for the efficiency parameters,based on two mathematically derived efficiency parameters,entropy rise coefficient and compression quality efficiency.Two efficiency parameters are then examined for equal intensity shocks system to show their capabilities in characterizing the quality of compression system with different compression degrees,and representing the average compression efficiency of the entire inlet.And the process efficiency and compression quality efficiency are compared in the Mollier diagram to afford a clear understanding of their difference in evaluating the overall and the local compression efficiency.展开更多
Compressing encrypted images remains a challenge.As illustrated in our previous work on compression of encrypted binary images,it is preferable to exploit statistical characteristics at the receiver.Through this line,...Compressing encrypted images remains a challenge.As illustrated in our previous work on compression of encrypted binary images,it is preferable to exploit statistical characteristics at the receiver.Through this line,we characterize statistical correlations between adjacent bitplanes of a gray image with the Markov random field(MRF),represent it with a factor graph,and integrate the constructed MRF factor graph in that for binary image reconstruction,which gives rise to a joint factor graph for gray images reconstruction(JFGIR).By exploiting the JFGIR at the receiver to facilitate the reconstruction of the original bitplanes and deriving theoretically the sum-product algorithm(SPA)adapted to the JFGIR,a novel MRF-based encryption-then-compression(ETC)scheme is thus proposed.After preferable universal parameters of the MRF between adjacent bitplanes are sought via a numerical manner,extensive experimental simulations are then carried out to show that the proposed scheme successfully compresses the first 3 and 4 most significant bitplanes(MSBs)for most test gray images and the others with a large portion of smooth area,respectively.Thus,the proposed scheme achieves significant improvement against the state-of-the-art leveraging the 2-D Markov source model at the receiver and is comparable or somewhat inferior to that using the resolution-progressive strategy in recovery.展开更多
We investigate the intensity and efficiency of a compressed echo, which is important in arbitrary waveform generation（AWG）. A new model of compressed echo is proposed based on the optical Bloch equations, which expo...We investigate the intensity and efficiency of a compressed echo, which is important in arbitrary waveform generation（AWG）. A new model of compressed echo is proposed based on the optical Bloch equations, which exposes much more detailed parameters than the conventional model, such as the time delay of the chirp lasers, the nature of the rare-earth-iondoped crystal, etc. According to the novel model of compressed echo, we find that reducing the time delay of the chirp lasers and scanning the lasers around the center frequency of the inhomogeneously broadened spectrum, while utilizing a crystal with larger coherence time and excitation lifetime can improve the compressed echo＇s intensity and efficiency. The theoretical analysis is validated by numerical simulations.展开更多
Air compressors are vital and have numerous industrial applications.Approximately 8%of the annual operating electricity consumption in industrial countries is constituted by due to the use of air compressors.Because t...Air compressors are vital and have numerous industrial applications.Approximately 8%of the annual operating electricity consumption in industrial countries is constituted by due to the use of air compressors.Because the poor heat transfer to the environment in the rapid compression process,the compression is non-isothermal,the efficiency of compressors is restricted.To improve their efficiency and achieve isothermal compression,this study proposes energy conversion reciprocating piston quasiisothermal compression using a water spray.First,a mathematical model of a reciprocating piston compressor with water sprays was established.Through experimental investigation and simulations,the mathematical model was validated.The energy conversion characteristics of the reciprocating piston compressor were then studied.To reduce compression power and enhance compression efficiency,it was first discovered that the critical parameters were the input pressure of the driving chamber,water spray mass,and compression volume ratio,which were then evaluated thoroughly.The higher the inlet pressure of the driving chamber,the faster the air compression velocity.Additionally,the compression efficiency was elevated as the water spray mass was gradually increased for a given compression volume ratio.When the compression volume ratio was increased from 2 to 3,the compression power increased from 172.7 J/stroke to 294.2 J/stroke and the compression efficiency was enhanced from 37.3%(adiabatic)to 80.6%.This research and its performance analysis can be referred to during the parameter design optimisation of reciprocating piston quasi-isothermal compression systems using water sprays.展开更多
The evolution of social network and multimedia technologies encourage more and more people to generate and upload visual information, which leads to the generation of large-scale video data. Therefore, preeminent comp...The evolution of social network and multimedia technologies encourage more and more people to generate and upload visual information, which leads to the generation of large-scale video data. Therefore, preeminent compression technologies are highly desired to facilitate the storage and transmission of these tremendous video data for a wide variety of applications. In this paper, a systematic review of the recent advances for large-scale video compression （LSVC） is presented. Specifically, fast video coding algorithms and effective models to improve video compression efficiency are introduced in detail, since coding complexity and compression efficiency are two important factors to evaluate video coding approaches. Finally, the challenges and fu- ture research trends for LSVC are discussed.展开更多
In the evolving landscape of the digital era,edge computing emerges as an essential paradigm,especially critical for low-latency,real-time applications and Internet of Things(IoT)environments.Despite its advantages,ed...In the evolving landscape of the digital era,edge computing emerges as an essential paradigm,especially critical for low-latency,real-time applications and Internet of Things(IoT)environments.Despite its advantages,edge computing faces severe limitations in storage capabilities and is fraught with reliability issues due to its resource-constrained nature and exposure to challenging conditions.To address these challenges,this work presents a tailored storage mechanism for edge computing,focusing on space efficiency and data reliability.Our method comprises three key steps:relation factorization,column clustering,and erasure encoding with compression.We successfully reduce the required storage space by deconstructing complex database tables and optimizing data organization within these sub-tables.We further add a layer of reliability through erasure encoding.Comprehensive experiments on TPC-H datasets substantiate our approach,demonstrating storage savings of up to 38.35%and time efficiency improvements by 3.96x in certain cases.Furthermore,our clustering technique shows a potential for additional storage reduction up to 40.41%.展开更多
基金supported by National Natural Science Foundation of China(Nos.11672309 and 11472279)。
文摘The efficiency parameters are studied in this paper for evaluating the compression quality of the inlets with different compression degrees and assessing different design methods.Selfconsistency is proposed for the efficiency parameters,based on two mathematically derived efficiency parameters,entropy rise coefficient and compression quality efficiency.Two efficiency parameters are then examined for equal intensity shocks system to show their capabilities in characterizing the quality of compression system with different compression degrees,and representing the average compression efficiency of the entire inlet.And the process efficiency and compression quality efficiency are compared in the Mollier diagram to afford a clear understanding of their difference in evaluating the overall and the local compression efficiency.
基金This work is supported in part by the National Natural Science Foundation of China under contracts 61672242 and 61702199in part by China Spark Program under Grant 2015GA780002+1 种基金in part by The National Key Research and Development Program of China under Grant 2017YFD0701601in part by Natural Science Foundation of Guangdong Province under Grant 2015A030313413.
文摘Compressing encrypted images remains a challenge.As illustrated in our previous work on compression of encrypted binary images,it is preferable to exploit statistical characteristics at the receiver.Through this line,we characterize statistical correlations between adjacent bitplanes of a gray image with the Markov random field(MRF),represent it with a factor graph,and integrate the constructed MRF factor graph in that for binary image reconstruction,which gives rise to a joint factor graph for gray images reconstruction(JFGIR).By exploiting the JFGIR at the receiver to facilitate the reconstruction of the original bitplanes and deriving theoretically the sum-product algorithm(SPA)adapted to the JFGIR,a novel MRF-based encryption-then-compression(ETC)scheme is thus proposed.After preferable universal parameters of the MRF between adjacent bitplanes are sought via a numerical manner,extensive experimental simulations are then carried out to show that the proposed scheme successfully compresses the first 3 and 4 most significant bitplanes(MSBs)for most test gray images and the others with a large portion of smooth area,respectively.Thus,the proposed scheme achieves significant improvement against the state-of-the-art leveraging the 2-D Markov source model at the receiver and is comparable or somewhat inferior to that using the resolution-progressive strategy in recovery.
基金Project supported by Special Funds for Scientific and Technological Innovation Projects in Tianjin,China(Grant No.10FDZDGX00400)the Tianjin Research Program of Application Foundation and Advanced Technology,China(Grant No.15JCQNJC01100)
文摘We investigate the intensity and efficiency of a compressed echo, which is important in arbitrary waveform generation（AWG）. A new model of compressed echo is proposed based on the optical Bloch equations, which exposes much more detailed parameters than the conventional model, such as the time delay of the chirp lasers, the nature of the rare-earth-iondoped crystal, etc. According to the novel model of compressed echo, we find that reducing the time delay of the chirp lasers and scanning the lasers around the center frequency of the inhomogeneously broadened spectrum, while utilizing a crystal with larger coherence time and excitation lifetime can improve the compressed echo＇s intensity and efficiency. The theoretical analysis is validated by numerical simulations.
基金supported by the National Natural Science Foundation of China(Grant Nos.51375028&51605013)the Pneumatic and Thermodynamic Energy Storage and Supply Beijing Key Laboratory
文摘Air compressors are vital and have numerous industrial applications.Approximately 8%of the annual operating electricity consumption in industrial countries is constituted by due to the use of air compressors.Because the poor heat transfer to the environment in the rapid compression process,the compression is non-isothermal,the efficiency of compressors is restricted.To improve their efficiency and achieve isothermal compression,this study proposes energy conversion reciprocating piston quasiisothermal compression using a water spray.First,a mathematical model of a reciprocating piston compressor with water sprays was established.Through experimental investigation and simulations,the mathematical model was validated.The energy conversion characteristics of the reciprocating piston compressor were then studied.To reduce compression power and enhance compression efficiency,it was first discovered that the critical parameters were the input pressure of the driving chamber,water spray mass,and compression volume ratio,which were then evaluated thoroughly.The higher the inlet pressure of the driving chamber,the faster the air compression velocity.Additionally,the compression efficiency was elevated as the water spray mass was gradually increased for a given compression volume ratio.When the compression volume ratio was increased from 2 to 3,the compression power increased from 172.7 J/stroke to 294.2 J/stroke and the compression efficiency was enhanced from 37.3%(adiabatic)to 80.6%.This research and its performance analysis can be referred to during the parameter design optimisation of reciprocating piston quasi-isothermal compression systems using water sprays.
基金This work was supported in part by the National Natural Science Foundation of China （Grant Nos. 61622115 and 61472281）, the Program for Professor of Special Appointment （Eastern Scholar） at Shanghai Institutions of Higher Learning （GZ2015005）, and Shanghai Engineering Research Center of Industrial Vision Perception ＆ Intelligent Computing （ 17DZ2251600）.
文摘The evolution of social network and multimedia technologies encourage more and more people to generate and upload visual information, which leads to the generation of large-scale video data. Therefore, preeminent compression technologies are highly desired to facilitate the storage and transmission of these tremendous video data for a wide variety of applications. In this paper, a systematic review of the recent advances for large-scale video compression （LSVC） is presented. Specifically, fast video coding algorithms and effective models to improve video compression efficiency are introduced in detail, since coding complexity and compression efficiency are two important factors to evaluate video coding approaches. Finally, the challenges and fu- ture research trends for LSVC are discussed.
基金supported by the State Grid technology project,China(5108-202218280A-2-394-XG),titled"Research and Ap-plication on Distributed New Energy Integration and Edge IoT Technology".
文摘In the evolving landscape of the digital era,edge computing emerges as an essential paradigm,especially critical for low-latency,real-time applications and Internet of Things(IoT)environments.Despite its advantages,edge computing faces severe limitations in storage capabilities and is fraught with reliability issues due to its resource-constrained nature and exposure to challenging conditions.To address these challenges,this work presents a tailored storage mechanism for edge computing,focusing on space efficiency and data reliability.Our method comprises three key steps:relation factorization,column clustering,and erasure encoding with compression.We successfully reduce the required storage space by deconstructing complex database tables and optimizing data organization within these sub-tables.We further add a layer of reliability through erasure encoding.Comprehensive experiments on TPC-H datasets substantiate our approach,demonstrating storage savings of up to 38.35%and time efficiency improvements by 3.96x in certain cases.Furthermore,our clustering technique shows a potential for additional storage reduction up to 40.41%.
