In 5G systems, massive multiple-input multiple-output (MIMO) has been adopted in base stations (BSs) to improve spectral efficiency and coverage. The traditional conductive performance test techniques are challenging ...In 5G systems, massive multiple-input multiple-output (MIMO) has been adopted in base stations (BSs) to improve spectral efficiency and coverage. The traditional conductive performance test techniques are challenging due to the unaffordable cost and high complexity when testing a large number of antennas. To solve this problem, the over-the-air (OTA) test has been presented, in which probe selection is the key to reduce the number of channel emulators and probes. In this paper, a novel artificial bee colony (ABC) algorithm is introduced to enhance the efficiency and accuracy of probe selection procedure. A sectoring- based multi-probe anechoic chamber (MPAC) is built to evaluate the throughput performance of massive MIMO equipped in 5G BS. In addition, link level simulation is carried out to evaluate the proposal’s performance gain under the commercial network assumptions, where the average throughput of three velocity is given with different SNR region. The results suggest that OTA chamber and multi-probe wall are available not only for 5G BSs, but also for user equipments (UEs) with end-to-end communication.展开更多
Working group on cooling power test of quenchants of Japanese Heat Treatment Society has studied on the new method for testing cooling power of aqueous quenchants. This method employed the cooling curve test of a new ...Working group on cooling power test of quenchants of Japanese Heat Treatment Society has studied on the new method for testing cooling power of aqueous quenchants. This method employed the cooling curve test of a new sliver rod probe, which has a metal-sheathed thermocouple at its geometrical center. The experimental study has clarified that the new silver probe has more excellent durability than the JIS silver probe employed for cooling power test of heat treating oils (JIS K 2242) and an aluminum alloy probe. Good repeatability and reproducibility of the cooling curves during polymer quenching have been confirmed. This new method is useful especially for cooling power test of aqueous quenchants used for solution heat treatment of aluminum alloys. This new silver rod probe is expected to be adopted for the revised version of JIS K 2242 as the cooling power test method for aqueous quenchants.展开更多
Technical committee for Japanese industrial standard of heat treating oils has studied on the new method for testing cooling power of aqueous quenchants. This method employed the cooling curve test of a new sliver rod...Technical committee for Japanese industrial standard of heat treating oils has studied on the new method for testing cooling power of aqueous quenchants. This method employed the cooling curve test of a new sliver rod probe, which has a metal-sheathed thermocouple at its geometrical center. The experimental study has clarified that this probe has the higher sensitivity and excellent durability. In order to standardize this probe for cooling power test of aqueous quenchants, the repeatability and reproducibility of test results etc. have been studied. D.O.P. (Di-2-ethylthexyl Phthalate) was used as reference quenching fluid for initial calibration and for periodic calibration verification of the probe and system. In addition, 10% brine was used to check the response capability of the probe and system to the sudden change of temperature. These procedures are established according to the experimental investigation. This new test method is going to be built in the revised version of JIS K 2242 "Heat treating oils" as the cooling power test method for aqueous quenchants.展开更多
By modifying the salicylic-acid moiety with electron-withdrawing or –donating groups, three new terbium complexes（LⅠ·Tb, LⅡ·Tb, L·（Ⅲ）Tb） based on tripodal carboxylate ligands were synthesized. D...By modifying the salicylic-acid moiety with electron-withdrawing or –donating groups, three new terbium complexes（LⅠ·Tb, LⅡ·Tb, L·（Ⅲ）Tb） based on tripodal carboxylate ligands were synthesized. Due to different pull-push electronic effects of ligands, the fluorescence intensities of these terbium complexes significantly varied, that is： LⅡ·Tb 〉L（Ⅲ）·Tb〉 LⅠ·Tb. Meanwhile, the characteristic peaks at 492 nm（5D4→7F6） and 547 nm（5 D4→7F5） showed ＂Off–On–Off＂ fluorescence response to various p H conditions,which indicated that all of them can be used as the highly sensitive pH fluorescent probes. Notably, using LⅡ·Tb with the best fluorescence performance as a probe, some patients＇ urine samples can be easily monitored through the response triggered by pH value. Therefore, LⅡ·Tb has the potential to auxiliarily diagnose some diseases in clinical practice through p H detection of routine urine test.展开更多
Galvanic corrosion on samples of AZ91D magnesium alloy coupled with 2A12 aluminum alloy during neutral salt spray test was investigated.The variations of the surface potential were measured using scanning kelvin probe...Galvanic corrosion on samples of AZ91D magnesium alloy coupled with 2A12 aluminum alloy during neutral salt spray test was investigated.The variations of the surface potential were measured using scanning kelvin probe（SKP）.The results showed that galvanic effect on the corrosion of AZ91D magnesium alloy is closely related to the potential difference between the anodic and cathodic materials.In the initial period,corrosion only occurred in a narrow area at the coupling interface because of the limited distance galvanic current.Then,the corrosion rate of 2A12 aluminum alloy was accelerated due to its poor stability in strong alkali environment,which was attributed to the strong alkalization caused by the corrosion of AZ91D magnesium alloy.With the increase of the potential of 2A12 aluminum alloy as a result of the continuous covering of corrosion products,the potential difference between the two materials was enlarged,which enhanced the galvanic corrosion.展开更多
The corrosion behavior of partly coated carbon steel was investigated by salt spray test and scanning Kelvin probe （SKP） in order to understand the long-term corrosion behavior of coated carbon steel in marine atmos...The corrosion behavior of partly coated carbon steel was investigated by salt spray test and scanning Kelvin probe （SKP） in order to understand the long-term corrosion behavior of coated carbon steel in marine atmosphere environment. The localized corrosion was accurately characterized by SKP in both coated and uncoated regions. The SKP results showed that Volta potential varied with the test time, and the more the corrosion products, the more positive the potential. The borderline between coated and uncoated regions of partly coated steel shifted towards the coated side with the increasing of test time. The coating disbonding rate could be determined according to the shift of potential borderline measured by SKP. The corrosion mechanism of partly coated steel in NaCl salt spray was discussed according to the potential maps and corrosion morphologies.展开更多
Recent developments in micro- and nano-satellites have attracted the interest of the research community worldwide. Many colleges and corporations have launched their satellites in space. Meanwhile, the space flexible ...Recent developments in micro- and nano-satellites have attracted the interest of the research community worldwide. Many colleges and corporations have launched their satellites in space. Meanwhile, the space flexible probe-cone docking system for micro- and nano-satellites has become an attractive topic. In this paper, a dynamic model of a space flexible probe-cone dock- ing system, in which the flexible beam technology is applied, is built based on the Kane method. The curves of impact force versus time are obtained by the Lagrange model, the Kane model, and the experimental method. The Lagrange model was presented in the reference and verified by both finite element simulation and experiment. The results of the three methods show good agreements on the condition that the beam flexibility and the initial relative velocity change. It is worth mentioning that the introduction of vectorial mechanics and analytical mechanics in the Kane method leads to a large reduction of differential operations and makes the modeling process much easier than that of the Lagrange method. Moreover, the influences of the beam flexibility and the initial relative velocity are discussed. It is concluded that the initial relative velocity of space docking operation should be controlled to a certain value in order to protect the docking system.展开更多
Bubble plumes are important during the process of air-sea exchange,and optical-fiber phase detection is a suitable way to observe bubble plumes entrained by breaking waves.This paper designs a new optical-fiber probe(...Bubble plumes are important during the process of air-sea exchange,and optical-fiber phase detection is a suitable way to observe bubble plumes entrained by breaking waves.This paper designs a new optical-fiber probe(OFP)made of sapphire to overcome the limitations of existing materials(e.g.,high brittleness,poor corrosion resistance,and narrow bandwidth)and thereby enhance the detection performance of the OFP by improving its structure.Based on total internal reflection and light refraction,a simulation model of the probe is established in the Zemax optical design software to optimize the probe tip and matching mode of the two probe tips.The results show that the optimum OFP tip is a conical sapphire one with a cone angle of 35°.Tests are then conducted on a bespoke OFP sensor,the results of which are consistent with those predicted theoretically.The simulation results lay the foundation for the integrated design of OFP sensors and the optimization of their internal optics.The findings could also be applied to OFPs with multiple tips.展开更多
A scramjet engine combustion efficiency measure system was designed.The combustion efficiency was measured by chromatography method,and the results of chromatography method were compared with those of temperature meth...A scramjet engine combustion efficiency measure system was designed.The combustion efficiency was measured by chromatography method,and the results of chromatography method were compared with those of temperature method.The results indicate that the combustion efficiency measured by chromatography method was 80.7%,lower than the combustion efficiency of 84.5%measured by temperature method;the combustion efficiency could be measured more precisely by chromatogram method than by temperature method.The combustion efficiency measure system based on chromatogram method can work well,and thus can be used to measure the combustion efficiency of scramjet engine.展开更多
Background: In India, tuberculosis (TB) is a major public health problem, and the advent of drug resistance TB (DR-TB) has worsened the situation. The Revised National TB Control Programme (RNTCP) has introduced unive...Background: In India, tuberculosis (TB) is a major public health problem, and the advent of drug resistance TB (DR-TB) has worsened the situation. The Revised National TB Control Programme (RNTCP) has introduced universal drug susceptibility testing (UDST) for all diagnosed TB cases in 2018. We conducted this study to know the advantage of implementing UDST when compared to selective testing existent in 2017 on key diagnostic cascade parameters and to identify the challenges in the implementation of UDST. Methods: The study was conducted in two districts of Karnataka, India during January 2017-December 2018. The quantitative part consisted of before-and-after design and the qualitative part consisted of descriptive design. Results: In 2017 (during selective testing/“before” period) out of the 2440 TB patients, 80 (3%) were diagnosed with Isoniazid and Rifampicin resistance patients;in contrast in 2018 (during UDST/“after” period) of the 5129 TB patients 258 (5%) were diagnosed with Isoniazid and Rifampicin resistance. However, the proportion of eligible patients tested for rifampicin resistance during the “after” period was 60% when compared to 100% during the “before” period and median turnaround time for testing was also longer during the “after” period when compared to the “before” period (32.5 days vs 27.5 days). Major reasons for these two gaps were found to be difficulties in collecting sputum specimens and transportation. Conclusion: The rollout of UDST has led to a three-fold increase in a number of DR-TB cases detected in the region. There is a need for the programme to increase the proportion tested for DST by increasing the laboratory capacity and address the challenges in sputum collection and transportation.展开更多
基金supported by the State Major Science and Technology Special Projects under Grant No. 2018ZX03001028-003
文摘In 5G systems, massive multiple-input multiple-output (MIMO) has been adopted in base stations (BSs) to improve spectral efficiency and coverage. The traditional conductive performance test techniques are challenging due to the unaffordable cost and high complexity when testing a large number of antennas. To solve this problem, the over-the-air (OTA) test has been presented, in which probe selection is the key to reduce the number of channel emulators and probes. In this paper, a novel artificial bee colony (ABC) algorithm is introduced to enhance the efficiency and accuracy of probe selection procedure. A sectoring- based multi-probe anechoic chamber (MPAC) is built to evaluate the throughput performance of massive MIMO equipped in 5G BS. In addition, link level simulation is carried out to evaluate the proposal’s performance gain under the commercial network assumptions, where the average throughput of three velocity is given with different SNR region. The results suggest that OTA chamber and multi-probe wall are available not only for 5G BSs, but also for user equipments (UEs) with end-to-end communication.
文摘Working group on cooling power test of quenchants of Japanese Heat Treatment Society has studied on the new method for testing cooling power of aqueous quenchants. This method employed the cooling curve test of a new sliver rod probe, which has a metal-sheathed thermocouple at its geometrical center. The experimental study has clarified that the new silver probe has more excellent durability than the JIS silver probe employed for cooling power test of heat treating oils (JIS K 2242) and an aluminum alloy probe. Good repeatability and reproducibility of the cooling curves during polymer quenching have been confirmed. This new method is useful especially for cooling power test of aqueous quenchants used for solution heat treatment of aluminum alloys. This new silver rod probe is expected to be adopted for the revised version of JIS K 2242 as the cooling power test method for aqueous quenchants.
文摘Technical committee for Japanese industrial standard of heat treating oils has studied on the new method for testing cooling power of aqueous quenchants. This method employed the cooling curve test of a new sliver rod probe, which has a metal-sheathed thermocouple at its geometrical center. The experimental study has clarified that this probe has the higher sensitivity and excellent durability. In order to standardize this probe for cooling power test of aqueous quenchants, the repeatability and reproducibility of test results etc. have been studied. D.O.P. (Di-2-ethylthexyl Phthalate) was used as reference quenching fluid for initial calibration and for periodic calibration verification of the probe and system. In addition, 10% brine was used to check the response capability of the probe and system to the sudden change of temperature. These procedures are established according to the experimental investigation. This new test method is going to be built in the revised version of JIS K 2242 "Heat treating oils" as the cooling power test method for aqueous quenchants.
基金supported by the National Natural Science Foundation of China (Nos. 21572091 and 21472075)the Fundamental Research Funds for the Central Universities (No. lzujbky-2016-51) by Ministry of Education of China
文摘By modifying the salicylic-acid moiety with electron-withdrawing or –donating groups, three new terbium complexes（LⅠ·Tb, LⅡ·Tb, L·（Ⅲ）Tb） based on tripodal carboxylate ligands were synthesized. Due to different pull-push electronic effects of ligands, the fluorescence intensities of these terbium complexes significantly varied, that is： LⅡ·Tb 〉L（Ⅲ）·Tb〉 LⅠ·Tb. Meanwhile, the characteristic peaks at 492 nm（5D4→7F6） and 547 nm（5 D4→7F5） showed ＂Off–On–Off＂ fluorescence response to various p H conditions,which indicated that all of them can be used as the highly sensitive pH fluorescent probes. Notably, using LⅡ·Tb with the best fluorescence performance as a probe, some patients＇ urine samples can be easily monitored through the response triggered by pH value. Therefore, LⅡ·Tb has the potential to auxiliarily diagnose some diseases in clinical practice through p H detection of routine urine test.
基金Funded by the National Natural Science Foundation of China(No.51271032)
文摘Galvanic corrosion on samples of AZ91D magnesium alloy coupled with 2A12 aluminum alloy during neutral salt spray test was investigated.The variations of the surface potential were measured using scanning kelvin probe（SKP）.The results showed that galvanic effect on the corrosion of AZ91D magnesium alloy is closely related to the potential difference between the anodic and cathodic materials.In the initial period,corrosion only occurred in a narrow area at the coupling interface because of the limited distance galvanic current.Then,the corrosion rate of 2A12 aluminum alloy was accelerated due to its poor stability in strong alkali environment,which was attributed to the strong alkalization caused by the corrosion of AZ91D magnesium alloy.With the increase of the potential of 2A12 aluminum alloy as a result of the continuous covering of corrosion products,the potential difference between the two materials was enlarged,which enhanced the galvanic corrosion.
基金the National Natural Science Foundation of China (Nos.50871021and50701006)
文摘The corrosion behavior of partly coated carbon steel was investigated by salt spray test and scanning Kelvin probe （SKP） in order to understand the long-term corrosion behavior of coated carbon steel in marine atmosphere environment. The localized corrosion was accurately characterized by SKP in both coated and uncoated regions. The SKP results showed that Volta potential varied with the test time, and the more the corrosion products, the more positive the potential. The borderline between coated and uncoated regions of partly coated steel shifted towards the coated side with the increasing of test time. The coating disbonding rate could be determined according to the shift of potential borderline measured by SKP. The corrosion mechanism of partly coated steel in NaCl salt spray was discussed according to the potential maps and corrosion morphologies.
基金supported in part by the National Natural Science Foundation of China (Nos. 91216201, 51205403)
文摘Recent developments in micro- and nano-satellites have attracted the interest of the research community worldwide. Many colleges and corporations have launched their satellites in space. Meanwhile, the space flexible probe-cone docking system for micro- and nano-satellites has become an attractive topic. In this paper, a dynamic model of a space flexible probe-cone dock- ing system, in which the flexible beam technology is applied, is built based on the Kane method. The curves of impact force versus time are obtained by the Lagrange model, the Kane model, and the experimental method. The Lagrange model was presented in the reference and verified by both finite element simulation and experiment. The results of the three methods show good agreements on the condition that the beam flexibility and the initial relative velocity change. It is worth mentioning that the introduction of vectorial mechanics and analytical mechanics in the Kane method leads to a large reduction of differential operations and makes the modeling process much easier than that of the Lagrange method. Moreover, the influences of the beam flexibility and the initial relative velocity are discussed. It is concluded that the initial relative velocity of space docking operation should be controlled to a certain value in order to protect the docking system.
文摘Bubble plumes are important during the process of air-sea exchange,and optical-fiber phase detection is a suitable way to observe bubble plumes entrained by breaking waves.This paper designs a new optical-fiber probe(OFP)made of sapphire to overcome the limitations of existing materials(e.g.,high brittleness,poor corrosion resistance,and narrow bandwidth)and thereby enhance the detection performance of the OFP by improving its structure.Based on total internal reflection and light refraction,a simulation model of the probe is established in the Zemax optical design software to optimize the probe tip and matching mode of the two probe tips.The results show that the optimum OFP tip is a conical sapphire one with a cone angle of 35°.Tests are then conducted on a bespoke OFP sensor,the results of which are consistent with those predicted theoretically.The simulation results lay the foundation for the integrated design of OFP sensors and the optimization of their internal optics.The findings could also be applied to OFPs with multiple tips.
文摘A scramjet engine combustion efficiency measure system was designed.The combustion efficiency was measured by chromatography method,and the results of chromatography method were compared with those of temperature method.The results indicate that the combustion efficiency measured by chromatography method was 80.7%,lower than the combustion efficiency of 84.5%measured by temperature method;the combustion efficiency could be measured more precisely by chromatogram method than by temperature method.The combustion efficiency measure system based on chromatogram method can work well,and thus can be used to measure the combustion efficiency of scramjet engine.
文摘Background: In India, tuberculosis (TB) is a major public health problem, and the advent of drug resistance TB (DR-TB) has worsened the situation. The Revised National TB Control Programme (RNTCP) has introduced universal drug susceptibility testing (UDST) for all diagnosed TB cases in 2018. We conducted this study to know the advantage of implementing UDST when compared to selective testing existent in 2017 on key diagnostic cascade parameters and to identify the challenges in the implementation of UDST. Methods: The study was conducted in two districts of Karnataka, India during January 2017-December 2018. The quantitative part consisted of before-and-after design and the qualitative part consisted of descriptive design. Results: In 2017 (during selective testing/“before” period) out of the 2440 TB patients, 80 (3%) were diagnosed with Isoniazid and Rifampicin resistance patients;in contrast in 2018 (during UDST/“after” period) of the 5129 TB patients 258 (5%) were diagnosed with Isoniazid and Rifampicin resistance. However, the proportion of eligible patients tested for rifampicin resistance during the “after” period was 60% when compared to 100% during the “before” period and median turnaround time for testing was also longer during the “after” period when compared to the “before” period (32.5 days vs 27.5 days). Major reasons for these two gaps were found to be difficulties in collecting sputum specimens and transportation. Conclusion: The rollout of UDST has led to a three-fold increase in a number of DR-TB cases detected in the region. There is a need for the programme to increase the proportion tested for DST by increasing the laboratory capacity and address the challenges in sputum collection and transportation.
