Software defined networking (SDN) and network function virtualization (NFV) have attracted significant attention from both academia and industry. Fortunately, by virtue of unique advantages of programmability and cent...Software defined networking (SDN) and network function virtualization (NFV) have attracted significant attention from both academia and industry. Fortunately, by virtue of unique advantages of programmability and centralized control, SDN has been widely used in various scenarios, such展开更多
With emergence of the BeiDou Navigation Satellite System(BDS), the Galileo Satellite Navigation System(Galileo), the Quasi-Zenith Satellite System(QZSS)and the restoration of the Global Navigation Satellite System(GLO...With emergence of the BeiDou Navigation Satellite System(BDS), the Galileo Satellite Navigation System(Galileo), the Quasi-Zenith Satellite System(QZSS)and the restoration of the Global Navigation Satellite System(GLONASS), the single Global Positioning System(GPS) has been gradually expanded into multiple global and regional navigation satellite systems(multi-GNSS/RNSS). In view of differences in these 5 systems, a consolidated multi-GNSS/RNSS precise point positioning(PPP) observation model is deduced in this contribution. In addition, the performance evaluation of PPP for multi-GNSS/RNSS is conducted using a large number of the multi-GNSS experiment(MGEX) station datasets. Experimental results show that multi-GNSS/RNSS can guarantee plenty of visible satellites effectively. Compared with single-system GPS, PDOP, HDOP, and VDOP values of the multi-GNSS/RNSS are improved by 46.8%, 46.5% and 46.3%, respectively. As for convergence time, the static and kinematic PPP of multi-GNSS/RNSS are superior to that of the single-system GPS, whose reliability, availability, and stability drop sharply with the increasing elevation cutoff. At satellite elevation cutoff of 40 °, the single-system GPS fails to carry out continuous positioning because of the insufficient visible satellites, while the multi-GNSS/RNSS PPP can still get positioning solutions with relatively high accuracy, especially in the horizontal direction.展开更多
Over the past decades SINOPEC has been uninterruptedly engaging in the development and upgrading of deep catalytic cracking （DCC） technology for manufacturing propylene from heavy oil. Recently SINOPEC after having ...Over the past decades SINOPEC has been uninterruptedly engaging in the development and upgrading of deep catalytic cracking （DCC） technology for manufacturing propylene from heavy oil. Recently SINOPEC after having made a lot of progress in the area of oil refining at the molecular level has developed a new generation DMMC-1 type catalyst designed for the DCC process. The laboratory evaluation tests have shown that compared to the existing MMC-2 type catalyst that features the best comprehensive performance, the DMMC-1 type catalyst has increased the propylene yield by 2.2% with the propylene selectivity increased by 10%. The said catalyst has improved its ability for heavy oil cracking and coke selectivity along with reduction of olefin content in gasoline to achieve a better product distribution and improve the product quality. The results of application of the said catalyst in a 650-kt/a commercial DCC unit at SINOPEC Anqing Branch Company have revealed that the DMMC- 1 catalyst demonstrated an enhanced capability for heavy oil cracking and could increase the total liquid yield to 84.56 m% from 83.92 m%, the LPG yield to 38.90 m % from 34.60 m %, the propylene yield to 17.80 m% from 15.37 m% and the propylene concentration to 45.91 m% from 44.91 m%, and reduce the coke yield from 7.61 m% to 7.05 m% and the olefin content in gasoline from 42.3 v% to 37.5 v%, resulting in an incremental profit amounting to 52.19 million RMB a year. This technology has further upgraded and developed the DCC technology which has been commanding a leading position among the industry peers.展开更多
To solve a real problem:how to calculate the reliability of a system with time-varying failure rates in industry systems,this paper studies a model for the load-sharing parallel system with time-varying failure rates,...To solve a real problem:how to calculate the reliability of a system with time-varying failure rates in industry systems,this paper studies a model for the load-sharing parallel system with time-varying failure rates,and obtains calculating formulas of reliability and availability of the system by solving differential equations.In this paper,the failure rates are expressed in polynomial configuration.The constant,linear and Weibull failure rate are in their special form.The polynomial failure rates provide flexibility in modeling the practical time-varying failure rates.展开更多
Application of advanced techniques and machine learning(ML)for designing and predicting the properties of engineered hydrochar/biochar is of great agro-environmental concern.Carbon(C)stability and phosphorus(P)availab...Application of advanced techniques and machine learning(ML)for designing and predicting the properties of engineered hydrochar/biochar is of great agro-environmental concern.Carbon(C)stability and phosphorus(P)availability in hydrochar(HC)are among the key limitations as they cannot be accurately predicted by traditional one-factor tests and might be overcome by engineering the pristine HC.Therefore,the aims of this study were(1)to determine the optimal production conditions of engineered swine manure HC with high C stability and P availability,and(2)to develop the best ML models to predict the properties of HC derived from different feedstocks.Pristine-(HC)and FeCl_(3)impregnated swine manure-derived HC(HC-Fe)were produced by hydrothermal carbonization under different pH(4,7,and 10),reaction temperature(180,220,and 260℃),and residence time(60,120,and 180 min)and characterized using thermo-gravimetric,microscopic,and spectroscopic analyses.Also,different ML algorithms were used to model and predict the hydrochar solid yield,properties,and nutrients content.FeCl_(3)impregnation increased Fe-phosphate content,while it reduced H/C and O/C ratios and hydroxyapatite P content,and therefore improved C stability and P availability in the HC-Fe as compared to HC,particularly under lower pH(4),temperature of 220℃,and at 120 min.The generalized additive ML model outperformed the other models for predicting the HC properties with a correlation coefficient of 0.86.The ML analysis showed that the most influential features on the hydrochar C stability were the H and O contents in the biomass,while P availability in HC was more dependent on the C,N and O contents in biomass.These results provided optimal production conditions for Fe-engineered manure hydrochar and identified the best performing ML model for predicting hydrochar properties.The main implication of this study is that it offers a high potential to improve the utilization of biowastes and produce biowastederived engineered hydrochar with high C stability and P availability on a large scale.展开更多
To ensure the reliability and availability of data,redundancy strategies are always required for distributed storage systems.Erasure coding,one of the representative redundancy strategies,has the advantage of low stor...To ensure the reliability and availability of data,redundancy strategies are always required for distributed storage systems.Erasure coding,one of the representative redundancy strategies,has the advantage of low storage overhead,which facilitates its employment in distributed storage systems.Among the various erasure coding schemes,XOR-based erasure codes are becoming popular due to their high computing speed.When a single-node failure occurs in such coding schemes,a process called data recovery takes place to retrieve the failed node’s lost data from surviving nodes.However,data transmission during the data recovery process usually requires a considerable amount of time.Current research has focused mainly on reducing the amount of data needed for data recovery to reduce the time required for data transmission,but it has encountered problems such as significant complexity and local optima.In this paper,we propose a random search recovery algorithm,named SA-RSR,to speed up single-node failure recovery of XOR-based erasure codes.SA-RSR uses a simulated annealing technique to search for an optimal recovery solution that reads and transmits a minimum amount of data.In addition,this search process can be done in polynomial time.We evaluate SA-RSR with a variety of XOR-based erasure codes in simulations and in a real storage system,Ceph.Experimental results in Ceph show that SA-RSR reduces the amount of data required for recovery by up to 30.0%and improves the performance of data recovery by up to 20.36%compared to the conventional recovery method.展开更多
文摘Software defined networking (SDN) and network function virtualization (NFV) have attracted significant attention from both academia and industry. Fortunately, by virtue of unique advantages of programmability and centralized control, SDN has been widely used in various scenarios, such
基金Supported by the National Natural Science Foundation of China (No. 41604018)the Fundamental Research Funds for the Central Universities(No. 2019B17514)+1 种基金Postgraduate Research&Practice Innovation Program of Jiangsu Province (No. nos. sjky19_05132019B60114)
文摘With emergence of the BeiDou Navigation Satellite System(BDS), the Galileo Satellite Navigation System(Galileo), the Quasi-Zenith Satellite System(QZSS)and the restoration of the Global Navigation Satellite System(GLONASS), the single Global Positioning System(GPS) has been gradually expanded into multiple global and regional navigation satellite systems(multi-GNSS/RNSS). In view of differences in these 5 systems, a consolidated multi-GNSS/RNSS precise point positioning(PPP) observation model is deduced in this contribution. In addition, the performance evaluation of PPP for multi-GNSS/RNSS is conducted using a large number of the multi-GNSS experiment(MGEX) station datasets. Experimental results show that multi-GNSS/RNSS can guarantee plenty of visible satellites effectively. Compared with single-system GPS, PDOP, HDOP, and VDOP values of the multi-GNSS/RNSS are improved by 46.8%, 46.5% and 46.3%, respectively. As for convergence time, the static and kinematic PPP of multi-GNSS/RNSS are superior to that of the single-system GPS, whose reliability, availability, and stability drop sharply with the increasing elevation cutoff. At satellite elevation cutoff of 40 °, the single-system GPS fails to carry out continuous positioning because of the insufficient visible satellites, while the multi-GNSS/RNSS PPP can still get positioning solutions with relatively high accuracy, especially in the horizontal direction.
文摘Over the past decades SINOPEC has been uninterruptedly engaging in the development and upgrading of deep catalytic cracking （DCC） technology for manufacturing propylene from heavy oil. Recently SINOPEC after having made a lot of progress in the area of oil refining at the molecular level has developed a new generation DMMC-1 type catalyst designed for the DCC process. The laboratory evaluation tests have shown that compared to the existing MMC-2 type catalyst that features the best comprehensive performance, the DMMC-1 type catalyst has increased the propylene yield by 2.2% with the propylene selectivity increased by 10%. The said catalyst has improved its ability for heavy oil cracking and coke selectivity along with reduction of olefin content in gasoline to achieve a better product distribution and improve the product quality. The results of application of the said catalyst in a 650-kt/a commercial DCC unit at SINOPEC Anqing Branch Company have revealed that the DMMC- 1 catalyst demonstrated an enhanced capability for heavy oil cracking and could increase the total liquid yield to 84.56 m% from 83.92 m%, the LPG yield to 38.90 m % from 34.60 m %, the propylene yield to 17.80 m% from 15.37 m% and the propylene concentration to 45.91 m% from 44.91 m%, and reduce the coke yield from 7.61 m% to 7.05 m% and the olefin content in gasoline from 42.3 v% to 37.5 v%, resulting in an incremental profit amounting to 52.19 million RMB a year. This technology has further upgraded and developed the DCC technology which has been commanding a leading position among the industry peers.
文摘To solve a real problem:how to calculate the reliability of a system with time-varying failure rates in industry systems,this paper studies a model for the load-sharing parallel system with time-varying failure rates,and obtains calculating formulas of reliability and availability of the system by solving differential equations.In this paper,the failure rates are expressed in polynomial configuration.The constant,linear and Weibull failure rate are in their special form.The polynomial failure rates provide flexibility in modeling the practical time-varying failure rates.
基金sustained by a grant from the National Key Research and Development Program of China“Intergovernmental Cooperation in International Science and Technology Innovation”[Grant number 2023YFE0104700]the National Natural Science Foundation of China[Grant Number 31401944]The author Esmat F.Ali extends his appreciation to Taif University,Saudi Arabia for supporting this work through project number(TU-DSPP-2024-27).
文摘Application of advanced techniques and machine learning(ML)for designing and predicting the properties of engineered hydrochar/biochar is of great agro-environmental concern.Carbon(C)stability and phosphorus(P)availability in hydrochar(HC)are among the key limitations as they cannot be accurately predicted by traditional one-factor tests and might be overcome by engineering the pristine HC.Therefore,the aims of this study were(1)to determine the optimal production conditions of engineered swine manure HC with high C stability and P availability,and(2)to develop the best ML models to predict the properties of HC derived from different feedstocks.Pristine-(HC)and FeCl_(3)impregnated swine manure-derived HC(HC-Fe)were produced by hydrothermal carbonization under different pH(4,7,and 10),reaction temperature(180,220,and 260℃),and residence time(60,120,and 180 min)and characterized using thermo-gravimetric,microscopic,and spectroscopic analyses.Also,different ML algorithms were used to model and predict the hydrochar solid yield,properties,and nutrients content.FeCl_(3)impregnation increased Fe-phosphate content,while it reduced H/C and O/C ratios and hydroxyapatite P content,and therefore improved C stability and P availability in the HC-Fe as compared to HC,particularly under lower pH(4),temperature of 220℃,and at 120 min.The generalized additive ML model outperformed the other models for predicting the HC properties with a correlation coefficient of 0.86.The ML analysis showed that the most influential features on the hydrochar C stability were the H and O contents in the biomass,while P availability in HC was more dependent on the C,N and O contents in biomass.These results provided optimal production conditions for Fe-engineered manure hydrochar and identified the best performing ML model for predicting hydrochar properties.The main implication of this study is that it offers a high potential to improve the utilization of biowastes and produce biowastederived engineered hydrochar with high C stability and P availability on a large scale.
基金the National Natural Science Foundation of China(No.62172327)。
文摘To ensure the reliability and availability of data,redundancy strategies are always required for distributed storage systems.Erasure coding,one of the representative redundancy strategies,has the advantage of low storage overhead,which facilitates its employment in distributed storage systems.Among the various erasure coding schemes,XOR-based erasure codes are becoming popular due to their high computing speed.When a single-node failure occurs in such coding schemes,a process called data recovery takes place to retrieve the failed node’s lost data from surviving nodes.However,data transmission during the data recovery process usually requires a considerable amount of time.Current research has focused mainly on reducing the amount of data needed for data recovery to reduce the time required for data transmission,but it has encountered problems such as significant complexity and local optima.In this paper,we propose a random search recovery algorithm,named SA-RSR,to speed up single-node failure recovery of XOR-based erasure codes.SA-RSR uses a simulated annealing technique to search for an optimal recovery solution that reads and transmits a minimum amount of data.In addition,this search process can be done in polynomial time.We evaluate SA-RSR with a variety of XOR-based erasure codes in simulations and in a real storage system,Ceph.Experimental results in Ceph show that SA-RSR reduces the amount of data required for recovery by up to 30.0%and improves the performance of data recovery by up to 20.36%compared to the conventional recovery method.
