Recently, the local government of Yibin Sichuan Province, sent 70 street sweepers to Singapore to learn from the country’s experience in keeping the city cleaner and more beautiful. This is the second time that the g...Recently, the local government of Yibin Sichuan Province, sent 70 street sweepers to Singapore to learn from the country’s experience in keeping the city cleaner and more beautiful. This is the second time that the government of Yibin sponsored street sweepers for an overseas study tou after tours to Hong Kong and Macao展开更多
Pickup mouth is a key component for the service performance of a street sweeper. Computational fluid dynamics( CFD) technology,as an analysis tool in fluid flow simulation,is employed in this work because it can great...Pickup mouth is a key component for the service performance of a street sweeper. Computational fluid dynamics( CFD) technology,as an analysis tool in fluid flow simulation,is employed in this work because it can greatly shorten the design period. To obtain higher simulation accuracy,the gas-solid coupling inside the process cannot be neglected during numerical simulation.Our optimization procedure considers the influence of structure and operational parameters. It is recommended that the outlet diameter is less than 0. 42 of the width and the outlet inclination angle is 110°for structure parameters. The dust collection efficiency is improved when the reverse flow rate is 70% of the total volume,the sweepertraveling speed is 10 km / h,and the pressure drop is 2 400 Pa.Simulation results exhibit well consistency with the physical experimental results.展开更多
Perch sweeper fish with scientific name Cobitis taenia is one of the Cobitidae family. Since this kind of fish lives in clean waters and in the high areas of Talar River, it can be an index on water implution. This su...Perch sweeper fish with scientific name Cobitis taenia is one of the Cobitidae family. Since this kind of fish lives in clean waters and in the high areas of Talar River, it can be an index on water implution. This survey on the diet of this specimen is done on two stations （Kaselian and Tajoon） and shallow and high areas of Talar River in Mazandaran （Southern part of Caspian sea） and the duration of this survey is from October 2008 till September 2009. We should mention that fishing was just done by electro-shocker with voltage 300 V. And this fish after fishing is fixation in 10% formalin solution. So 410 perch sweeper fish were examined and the average of relatively length of gut （RLG） was 17.35 cm. The index of vacated intestine （VI） was calculated 43.35% for all samples. From intense of diet points of view （GSI）, the most frequency of full intestines was considered in summer and spring. On the other hand, the smallness of relatively length of gut index （RLG 〈 1） shows that perch sweeper fish＇s diet manner is inclined to herbivority. In the examination of containing of digestive track, overally 10 kinds of foodstuff were known. Based on amount of this index, 2.67% Chironomidae is known as main bait in all sampling period.展开更多
The collision between satellites IRIDIUM 33 and COSMOS 2251 indicated that the clash of two on-orbit satellites was becoming an inevitable reality. Our calculation with the two-line orbit element by NORAD showed that ...The collision between satellites IRIDIUM 33 and COSMOS 2251 indicated that the clash of two on-orbit satellites was becoming an inevitable reality. Our calculation with the two-line orbit element by NORAD showed that some two geostationary satellites had approached very close in July 2009. Therefore, more attention should be given to avoid such collisions. This paper analyzes the orbital long-term variation of a dead satellite drifting in the geostationary orbit. Also, the negative effects posed by dead satellites upon the on-orbit operational geostationary satellites are studied. Then the paper proposes a novel idea to launch a satellite sweeper whose purpose is to collect the on-orbit dead satellites and help them de-orbit to a "graveyard". The satellite sweeper consists of a parent satellite and a child satellite. The child satellite collects a dead satellite and transfers it to a higher orbit. The parent satellite stationed in the geostationary orbit is in charge of refueling the child satellite. The strategy of maneuver and rendezvous is presented and a series of formulas are derived. The analysis results show that our method to clean the geostationary orbital zone is practical and fuel-saving. With the help of just a few satellite sweepers, we can gain a clean environment of geostationary orbit environment again.展开更多
The impact of microwave sweeper power fluctuation in the BOTDA system has been theoretically analyzed and experimentally tested. And a novel method comparing real-time acquisition of probe wave power with a new algori...The impact of microwave sweeper power fluctuation in the BOTDA system has been theoretically analyzed and experimentally tested. And a novel method comparing real-time acquisition of probe wave power with a new algorithm to realize probe wave power normalization for eliminating this impact was proposed. The principle of the proposed method was described theoretically. And the contrast test between our new method and conventional one was carried out. The experiment results indicated that the temperature accuracy was effectively improved from ＋5 C to 2 C.展开更多
文摘Recently, the local government of Yibin Sichuan Province, sent 70 street sweepers to Singapore to learn from the country’s experience in keeping the city cleaner and more beautiful. This is the second time that the government of Yibin sponsored street sweepers for an overseas study tou after tours to Hong Kong and Macao
基金National Natural Science Foundation of China(No.51375202)
文摘Pickup mouth is a key component for the service performance of a street sweeper. Computational fluid dynamics( CFD) technology,as an analysis tool in fluid flow simulation,is employed in this work because it can greatly shorten the design period. To obtain higher simulation accuracy,the gas-solid coupling inside the process cannot be neglected during numerical simulation.Our optimization procedure considers the influence of structure and operational parameters. It is recommended that the outlet diameter is less than 0. 42 of the width and the outlet inclination angle is 110°for structure parameters. The dust collection efficiency is improved when the reverse flow rate is 70% of the total volume,the sweepertraveling speed is 10 km / h,and the pressure drop is 2 400 Pa.Simulation results exhibit well consistency with the physical experimental results.
文摘Perch sweeper fish with scientific name Cobitis taenia is one of the Cobitidae family. Since this kind of fish lives in clean waters and in the high areas of Talar River, it can be an index on water implution. This survey on the diet of this specimen is done on two stations （Kaselian and Tajoon） and shallow and high areas of Talar River in Mazandaran （Southern part of Caspian sea） and the duration of this survey is from October 2008 till September 2009. We should mention that fishing was just done by electro-shocker with voltage 300 V. And this fish after fishing is fixation in 10% formalin solution. So 410 perch sweeper fish were examined and the average of relatively length of gut （RLG） was 17.35 cm. The index of vacated intestine （VI） was calculated 43.35% for all samples. From intense of diet points of view （GSI）, the most frequency of full intestines was considered in summer and spring. On the other hand, the smallness of relatively length of gut index （RLG 〈 1） shows that perch sweeper fish＇s diet manner is inclined to herbivority. In the examination of containing of digestive track, overally 10 kinds of foodstuff were known. Based on amount of this index, 2.67% Chironomidae is known as main bait in all sampling period.
基金supported by the National Natural Science Foundation of China (Grant No. 60172029)
文摘The collision between satellites IRIDIUM 33 and COSMOS 2251 indicated that the clash of two on-orbit satellites was becoming an inevitable reality. Our calculation with the two-line orbit element by NORAD showed that some two geostationary satellites had approached very close in July 2009. Therefore, more attention should be given to avoid such collisions. This paper analyzes the orbital long-term variation of a dead satellite drifting in the geostationary orbit. Also, the negative effects posed by dead satellites upon the on-orbit operational geostationary satellites are studied. Then the paper proposes a novel idea to launch a satellite sweeper whose purpose is to collect the on-orbit dead satellites and help them de-orbit to a "graveyard". The satellite sweeper consists of a parent satellite and a child satellite. The child satellite collects a dead satellite and transfers it to a higher orbit. The parent satellite stationed in the geostationary orbit is in charge of refueling the child satellite. The strategy of maneuver and rendezvous is presented and a series of formulas are derived. The analysis results show that our method to clean the geostationary orbital zone is practical and fuel-saving. With the help of just a few satellite sweepers, we can gain a clean environment of geostationary orbit environment again.
文摘The impact of microwave sweeper power fluctuation in the BOTDA system has been theoretically analyzed and experimentally tested. And a novel method comparing real-time acquisition of probe wave power with a new algorithm to realize probe wave power normalization for eliminating this impact was proposed. The principle of the proposed method was described theoretically. And the contrast test between our new method and conventional one was carried out. The experiment results indicated that the temperature accuracy was effectively improved from ＋5 C to 2 C.
