In this study, Yangmeikeng mountain area with a long-term natural restoration status (communities 1, 2, and 3) and Chiao mountain area with an artificially disturbed status (communities 4 and 5) in Shenzhen in China w...In this study, Yangmeikeng mountain area with a long-term natural restoration status (communities 1, 2, and 3) and Chiao mountain area with an artificially disturbed status (communities 4 and 5) in Shenzhen in China were subjected to plant community composition and diversity statistical analysis on the basis of the following indices: plant height;density;tree layer DBH;coverage;number of family, genus, and species;calculated diversity indices;richness;similarity coefficients of family, genus and species;and species evenness. The diversity levels of each index in each community were compared, and the relationships of family, genus, and species in the communities with one another were determined. The integrated diversity levels in the two areas were also analyzed. Results showed that the composition status of three communities, especially communities 2 and 3, which were located at high elevation, in Yangmeikeng with the long-term natural restoration status was better. The diversity values were also evidently higher. The vegetation composition in Yangmeikeng was also greater than that in Chiao. The integration status of numerous diversity indices, such as evenness and richness, was higher than that of the latter. These data could be used as a basis for arguments regarding the status of natural and artificial forest biodiversities. Many species in the community in artificial forests were shrubs and herbs. The richness and proportion of tree species were distinctly low. Thus, shrubs and herbs were the main components of the artificial interference community. The number and richness of the tree species in natural or long-term natural restoration forests were higher than those of the former. The family diversity D<sub>f</sub> of the three communities in Yangmeikeng was slightly lower than that of the two communities in Chiao. By contrast, the genus diversity D<sub>g</sub>, family richness, and genus richness in Yangmeikeng were higher than those in Chiao. In terms of α-diversity and similarity coefficient, family, genus, and species were not directly related to one another. Therefore, species, genus, and family composition should be combined with their diversity status in the statistical and biodiversity analysis of a community. Synthetic diversity indices should be further analyzed to evaluate the diversity status of a community objectively.展开更多
In this paper, a deep learning-based method is proposed for crowdcountingproblems. Specifically, by utilizing the convolution kernel densitymap, the ground truth is generated dynamically to enhance the featureextracti...In this paper, a deep learning-based method is proposed for crowdcountingproblems. Specifically, by utilizing the convolution kernel densitymap, the ground truth is generated dynamically to enhance the featureextractingability of the generator model. Meanwhile, the “cross stage partial”module is integrated into congested scene recognition network (CSRNet) toobtain a lightweight network model. In addition, to compensate for the accuracydrop owing to the lightweight model, we take advantage of “structuredknowledge transfer” to train the model in an end-to-end manner. It aimsto accelerate the fitting speed and enhance the learning ability of the studentmodel. The crowd-counting system solution for edge computing is alsoproposed and implemented on an embedded device equipped with a neuralprocessing unit. Simulations demonstrate the performance improvement ofthe proposed solution in terms of model size, processing speed and accuracy.The performance on the Venice dataset shows that the mean absolute error(MAE) and the root mean squared error (RMSE) of our model drop by32.63% and 39.18% compared with CSRNet. Meanwhile, the performance onthe ShanghaiTech PartB dataset reveals that the MAE and the RMSE of ourmodel are close to those of CSRNet. Therefore, we provide a novel embeddedplatform system scheme for public safety pre-warning applications.展开更多
From Jan</span><span style="font-family:Verdana;">.</span><span style="font-family:Verdana;"> 2013 to Nov</span><span style="font-family:Verdana;">.<...From Jan</span><span style="font-family:Verdana;">.</span><span style="font-family:Verdana;"> 2013 to Nov</span><span style="font-family:Verdana;">.</span><span style="font-family:Verdana;"> 2018, we carried out the investigation on vegetation studies in the ecological monitoring programs, Shenzhen</span><span style="font-family:Verdana;"> and</span><span style="font-family:""><span style="font-family:Verdana;"> totally researched 170 plant communities of mountain areas etc., </span><span style="font-family:Verdana;">few areas of street regions and parks etc., for communities’ structural characteristics and plant diversity. We comparatively analyzed natural forests, semi-natural forest and artificial forest composition and structural characters and family, genus and species diversity level and the main affected factors. We also researched and analyzed these communities’ structural characteristics and pant diversity, </span><span style="font-family:Verdana;">comparatively analyzed natural forests, semi-natural forest and artificial forest composition and structural characters and family, genus and species diversity level, the main affected factors;researched and analyzed the relationship between plant community structure characteristics with the absorbing ability to PM</span><sub><span style="font-family:Verdana;">2.5</span></sub><span style="font-family:Verdana;"> pollutants. The result showed that the structure and plant diversity of natural </span><span style="font-family:Verdana;">forest </span></span><span style="font-family:Verdana;">were </span><span style="font-family:Verdana;">obviously better than</span><span style="font-family:Verdana;"> artificial disturbed forest or artificial forest, the semi-natural forest w</span><span style="font-family:Verdana;">as</span><span style="font-family:Verdana;"> the middle level of the forests, In the indices of height, DBH, coverage and crow width etc. of tree layer, natural forests and semi-natural forests were obvious higher than that of artificial disturbed forest or artificial forest;in some forests of artificial disturbed forest or artificial forest, though their richness indices of family and genus were a slightly higher, but this contribution was majorly due to herb layer plants, and some shrub layer plants. Analyz</span><span style="font-family:Verdana;">ing</span><span style="font-family:Verdana;"> three kinds of communities, the number of tree layer species of natural forest was</span><span style="font-family:Verdana;"> the </span><span style="font-family:""><span style="font-family:Verdana;">largest, and their every </span><i><span style="font-family:Verdana;">α</span></i><span style="font-family:Verdana;">-diversity index value was </span></span><span style="font-family:Verdana;">the </span><span style="font-family:Verdana;">highest;these characteristics values of semi-natural forest were second, artificial disturbed forests or artificial forests were </span><span style="font-family:Verdana;">the </span><span style="font-family:""><span style="font-family:Verdana;">lowest;in shrub layer, and herb layer, few </span><i><span style="font-family:Verdana;">α</span></i><span style="font-family:Verdana;">-diversity indices of artificial disturbed forest or artificial forest were </span><span style="font-family:Verdana;">a slightly higher than that of some natural forests, but the integral values of the diversity indices of natural forest and semi-natural forest were obvious</span></span><span style="font-family:Verdana;">ly</span><span style="font-family:Verdana;"> higher than the former. The research showed that in the artificial disturbed forest or artificial forest, because there have some little scale clearing area</span><span style="font-family:Verdana;">s</span><span style="font-family:""><span style="font-family:Verdana;">, so some pioneer plant species could enter the community and formed a temporarily </span><span style="font-family:Verdana;">increase of species diversity, however</span></span><span style="font-family:Verdana;">,</span><span style="font-family:Verdana;"> these species major </span><span style="font-family:Verdana;">were</span><span style="font-family:Verdana;"> some shrub and herb plants;but tree layer possessed obvious</span><span style="font-family:Verdana;">ly</span><span style="font-family:Verdana;"> more, even surpass</span><span style="font-family:Verdana;">ed</span><span style="font-family:Verdana;"> several ten times biomass than shrub and herb layers</span><span style="font-family:Verdana;">.</span><span style="font-family:Verdana;"> Therefore</span><span style="font-family:Verdana;">,</span><span style="font-family:Verdana;"> the respect</span><span style="font-family:Verdana;">s</span><span style="font-family:""><span style="font-family:Verdana;"> of maintain ecosystem stability and other</span><span style="font-family:Verdana;"> ecological efficient have </span><span style="font-family:Verdana;">major and dominated position and so on;and then this community can </span></span><span style="font-family:Verdana;">be </span><span style="font-family:Verdana;">natural recovery and succession, those forementioned new entire plants shall withdraw from the community and are replaced by the original plants of the community;but this process has already caused the ecological efficient loss and ecosystem unstable. Above research results are better evidence and theory reference to the argument problems on that </span><span style="font-family:Verdana;">are</span><span style="font-family:""><span style="font-family:Verdana;"> natural forest and natural restoration forest biodiversity higher? or is artificial forest biodiversity higher? and or is more artificial disturbed forest higher?</span><span style="font-family:Verdana;"> Our researches showed that used random investigation method set quadrats, and combined typical investigation method, the structural indices in the all layer of community and all diversity indices of tree, shrub and herb layers and the integral values </span></span><span style="font-family:Verdana;">were</span><span style="font-family:""><span style="font-family:Verdana;"> similar, same or usually these indices in the community which set 600 m</span><sup><span style="font-family:Verdana;">2</span></sup><span style="font-family:Verdana;">, 800 m</span><sup><span style="font-family:Verdana;">2</span></sup><span style="font-family:Verdana;"> total quatrat area were higher (</span><i><span style="font-family:Verdana;">α</span></i><span style="font-family:Verdana;">-diversity) than that of more than 3000 m</span><sup><span style="font-family:Verdana;">2</span></sup><span style="font-family:Verdana;">, 4000 m</span><sup><span style="font-family:Verdana;">2</span></sup><span style="font-family:Verdana;"> or 7000 m</span><sup><span style="font-family:Verdana;">2</span></sup><span style="font-family:Verdana;">, even more than 17,000 m</span><sup><span style="font-family:Verdana;">2</span></sup><span style="font-family:Verdana;"> total qua</span></span><span style="font-family:Verdana;">d</span><span style="font-family:Verdana;">rat area of communities. These lot</span><span style="font-family:Verdana;">s</span><span style="font-family:""><span style="font-family:Verdana;"> of researches further proved that according to minimum area method for vegetation survey, in subtropical region, using random investigation method combined with typical investigation set 400 m</span><sup><span style="font-family:Verdana;">2</span></sup><span style="font-family:Verdana;"> or 400 m</span><sup><span style="font-family:Verdana;">2</span></sup><span style="font-family:Verdana;"> - 500 m</span><sup><span style="font-family:Verdana;">2</span></sup><span style="font-family:Verdana;"> total qua</span></span><span style="font-family:Verdana;">d</span><span style="font-family:""><span展开更多
Oligodendrocyte lineage gene 1 plays a key role in hypoxic-ischemic brain damage and myelin repair, miRNA-9 is involved in the occurrence of many related neurological disorders. Bioin- formatics analysis demonstrated ...Oligodendrocyte lineage gene 1 plays a key role in hypoxic-ischemic brain damage and myelin repair, miRNA-9 is involved in the occurrence of many related neurological disorders. Bioin- formatics analysis demonstrated that miRNA-9 complementarily, but incompletely, bound oligodendrocyte lineage gene 1, but whether miRNA-9 regulates oligodendrocyte lineage gene 1 remains poorly understood. Whole brain slices of 3-day-old Sprague-Dawley rats were cultured and divided into four groups: control group; oxygen-glucose deprivation group (treatment with 8% O2 + 92% N2 and sugar-free medium for 60 minutes); transfection control group (after oxygen and glucose deprivation for 60 minutes, transfected with control plasmid) and miRNA-9 transfection group (after oxygen and glucose deprivation for 60 minutes, transfected with miRNA-9 plasmid). From the third day of transfection, and with increasing culture days, oligodendrocyte lineage gene 1 expression increased in each group, peaked at 14 days, and then decreased at 21 days. Real-time quantitative PCR results, however, demonstrated that oligoden- drocyte lineage gene 1 expression was lower in the miRNA-9 transfection group than that in the transfection control group at 1, 3, 7, 14, 21 and 28 days after transfection. Results suggested that miRNA-9 possibly negatively regulated oligodendrocyte lineage gene 1 in brain tissues during hypoxic-ischemic brain damage.展开更多
Exploring inexpensive and efficient bifunctional electrocatalysts for oxygen reduction reaction(ORR) and oxygen evolution reaction(OER) is critical for rechargeable metal-air batteries. Herein, we report a new 3D hier...Exploring inexpensive and efficient bifunctional electrocatalysts for oxygen reduction reaction(ORR) and oxygen evolution reaction(OER) is critical for rechargeable metal-air batteries. Herein, we report a new 3D hierarchical sulfur and nitrogen co-doped carbon nanocages(hSNCNC) as a promising bifunctional oxygen electrocatalyst by an in-situ MgO template method with pyridine and thiophene as the mixed precursor. The as-prepared h SNCNC exhibits a positive half-wave potential of 0.792 V(vs. reversible hydrogen electrode, RHE) for ORR, and a low operating potential of 1.640 V at a 10 mA cm-2 current density for OER. The reversible oxygen electrode index is 0.847 V, far superior to commercial Pt/C and IrO2,which reaches the top level of the reported bifunctional catalysts. Consequently, the hSNCNC as air cathodes in an assembled Zn-air battery features low charge/discharge overpotential and long lifetime. The remarkable properties arises from the introduced multiple heteroatom dopants and stable 3D hierarchical structure with multi-scale pores, which provides the abundant uniform high-active S and N species and efficient charge transfer as well as mass transportation. These results demonstrate the potential strategy in developing suitable carbon-based bi-/multi-functional catalysts to enable the next generation of the rechargeable metal-air batteries.展开更多
The mechanism of bolt support is an important topic in mining engineering and slope treatment. The artificial material and loading system were self-developed to study the influence of bedding cohesion and bolt number ...The mechanism of bolt support is an important topic in mining engineering and slope treatment. The artificial material and loading system were self-developed to study the influence of bedding cohesion and bolt number on the anchoring behavior of bedded rock mass. The results show that, both peak strength and elasticity modulus increase gradually with the increase of bedding cohesion and bolt number. The axial stress–strain curve of bedded rock mass under the reinforcement of bolts presents the features of strain-softening and secondary strengthening. Finally, anchoring behavior of bedded rock mass with different bolt numbers was simulated by using FLAC3 D numerical program and the results were compared with the experimental results. This study can provide certain bases to the stability control and support design of bedded rock mass in roadway.展开更多
Air cathodes with high electrocatalytic activity are vital for developing H2/O_(2) proton exchange membrane fuel cells(PEMFC)and Zn-air batteries.However,the state-of-the-art air cathodes suffer from either limited ca...Air cathodes with high electrocatalytic activity are vital for developing H2/O_(2) proton exchange membrane fuel cells(PEMFC)and Zn-air batteries.However,the state-of-the-art air cathodes suffer from either limited catalytic activity or high cost,which thus hinder their applications.Herein,we designed ZIF-8 derived nitrogen and atomic iron dual-doped porous carbon nanocubes as high-quality catalysts for ORR,through a novel gas-doping approach.The porous carbon nanocubic architecture and abundant Fe-Nxactive species endow ZIF-8 derived single atomic iron catalyst(PCN-A@Fe SA)with superior catalytic activity,and surpass Pt/C and a majority of the reported catalysts.Both XAS and DFT calculations suggest that Fe2+N4 moieties are the main active centers that are favorable for oxygen affinity and OH*intermediate desorption,which can result in promising catalytic performance.Most importantly,PCNA@Fe SA can achieve power density of 514 m W cm^(-2) as cathodic catalyst in a PEMFC and discharge peak power density of 185 m W cm^(-2) in an alkaline Zn-air battery.The outstanding performance is derived from both the high specific surface area and high-density of iron single atom in nitrogen doped nanocubic carbon matrix.展开更多
The friction pull plug welding(FPPW)of the 2219-T87 tungsten inert gas(TIG)welded joint was investigated,and the microstructures,precipitate evolution,mechanical properties,and fracture morphologies of this joint were...The friction pull plug welding(FPPW)of the 2219-T87 tungsten inert gas(TIG)welded joint was investigated,and the microstructures,precipitate evolution,mechanical properties,and fracture morphologies of this joint were analyzed and discussed.In this study,defectfree joints were obtained using a rotational speed of 7000 r/min,an axial feeding displacement of 12 mm,and an axial force of 20-22 kN.The results indicated that within these welding parameters,metallurgical bonding between the plug and plate is achieved by the formation of recrystallized grains.The microstructural features of the FPPW joint can be divided into different regions,including the heat-affected zone(HAZ),thermomechanically affected zone(TMAZ),recrystallization zone(RZ),heat-affected zone in the TIG weld(TIG-HAZ),and the thermomechanically affected zone in the TIG weld(TIG-TMAZ).In the TIG-TMAZ,the grains were highly deformed and elongated due to the shear and the extrusion that produces the plug during the FPPW process.The main reason for the softening in the TMAZ is determined to be the dissolution ofθ’and coarsening ofθprecipitate particles.In a tensile test,the FPPW joint welded with an axial force of 22 kN showed the highest ultimate tensile strength of 237 MPa.The locations of cracks and factures in the TIG-TMAZ were identified.The fracture morphology of the tensile sample showed good plasticity and toughness of the joints.展开更多
In this study,we investigated the hydrogen evolution reaction(HER)on the(101)facet of pristine and W-doped CoP using the density functional theory.Two types of Co atoms are identified on the catalyst surface:the Co at...In this study,we investigated the hydrogen evolution reaction(HER)on the(101)facet of pristine and W-doped CoP using the density functional theory.Two types of Co atoms are identified on the catalyst surface:the Co atoms that present the higher d band center are marked as valid sites,whereas the others are marked as invalid sites owing to their weaker H adsorption ability.It is further revealed that W-doping can decrease the d band center of the surface Co atoms,which is beneficial for the HER;however the exposure to W weakens the desorption of H.To address the strong adsorption effect of W,the doping sites and dopant content are analyzed,and the results indicate that 8.4 wt%W doping at the invalid surface Co sites is preferred;moreover,the optimal W content increases to 16.8 wt%when W is inserted into the subsurface.The effect of W doping is weakened when the doping site is far away from the surface.展开更多
To improve the energy utilization efficiency of metal bridge foil explosion, and increase the function range of plasmas, array bridge foil explosion experiments with different structures were performed. A Schlieren ph...To improve the energy utilization efficiency of metal bridge foil explosion, and increase the function range of plasmas, array bridge foil explosion experiments with different structures were performed. A Schlieren photographic measurement system with a double-pulse laser source was used to observe the flow field of a bridge foil explosion. The evolution laws of plasmas and shock waves generated by array bridge foil explosions of different structures were analyzed and compared. A multi-phase flow calculation model was established to simulate the electrical exploding process of a metal bridge foil. The plasma equation of state was determined by considering the effect of the changing number of particles and Coulomb interaction on the pressure and internal energy. The ionization degree of the plasma was calculated via the Saha-Eggert equation assuming conditions of local thermal equilibrium. The exploding process of array bridge foils was simulated, and the superposition processes of plasma beams were analyzed. The variation and distribution laws of the density, temperature, pressure, and other important parameters were obtained. The results show that the array bridge foil has a larger plasma jet diameter than the single bridge foil for an equal total area of the bridge foil. We also found that the temperature, pressure, and density of the plasma jet's center region sharply increase because of the superposition of plasma beams.展开更多
In this paper the atomization character of the pressure-swirl injector was measured by using the Phase Doppler Particle Analyzer (PDPA) in the section of 150 mm below the outlet of the orifice. The orifice diameter of...In this paper the atomization character of the pressure-swirl injector was measured by using the Phase Doppler Particle Analyzer (PDPA) in the section of 150 mm below the outlet of the orifice. The orifice diameter of the pressure-swirl injector is 0.62 mm. The atomization character includes the spray angle, the water flow rate, the Sauter mean diameter (SMD), the velocity of the particles and their distribution in the radial and the axial directions under the pressure from 1 MPa to 4.5 MPa. After that the atomization character of the pressure-swirl injector was simulated in the DPM panel. The same atomization character of the injector was calculated and compared with the experimental data. The simulation was corrected by using the experimental data which can make it accurately and the model can be used to predict and calculate the atomization character of different injectors.展开更多
This study investigated multiple aspects of vulnerability to HIV in out-of-school adolescents and youth in Yunnan Province, a high HIV risk region in China. The findings show that socially disadvantaged adolescents an...This study investigated multiple aspects of vulnerability to HIV in out-of-school adolescents and youth in Yunnan Province, a high HIV risk region in China. The findings show that socially disadvantaged adolescents and youth were overrepresented in the out-of-school young people in Yunnan. The out-of-school young people in Yunnan exhibited 1) limited knowledge about HIV transmission and prevention, 2) a high prevalence of unprotected sexual activity, 3) high exposure to illicit drugs and alcohol use and a high prevalence of drug use in themselves, and 4) limited access to health services. There is an indication of higher exposure to risk behaviours in the younger age group. The study population used multiple media, particularly television, internet and radio, to obtain information about HIV transmission and prevention, particularly in the younger age group. These media may be an effective way of reaching this population in future HIV education and prevention programs in the region.展开更多
[Objective]The paper was to study the relationship between spatial distribution characteristics of soil p H and bacterial wilt in tobacco-growing area in Henan Province.[Method]The 21 tobacco-growing fields infected b...[Objective]The paper was to study the relationship between spatial distribution characteristics of soil p H and bacterial wilt in tobacco-growing area in Henan Province.[Method]The 21 tobacco-growing fields infected by bacterial wilt and 91 tobacco-growing fields with no cases were selected from Henan Province,and the pH of fields was determined.[Result]Bacterial wilt mainly occurred in the tobacco-growing fields in Luoshan,Pingqiao,Queshan,Biyang,Suiping,and Xiping,and the soil pH mainly ranged from 5.5 to 6.5(accounted for 84.75%of total surveyed tobacco fields);bacterial wilt had not been found in tobacco-growing fields in Tanghe,Zhengyang,Shangcai,Sheqi,Wuyang and Chenqu,and the soil pH mainly ranged from 6.5 to 7.0(accounted for 81.25%of total surveyed tobacco fields).There were significant differences in soil pH between the fields with and without bacterial wilt,and soil pH 6.5 could be regarded as the threshold for the occurrence of tobacco bacterial wilt in Henan Province.There was extremely significantly positive linear correlation between soil p H and latitude(y=0.7375 x-17.799,R2=0.386,P<0.01).The geographical boundary of soil pH 6.5 was roughly 33°N,and bacterial wilt was less likely to occur in the north tobacco-growing areas of the boundary.[Conclusion]The study will provide a scientific basis for the prevention and control of tobacco bacterial wilt in Henan.展开更多
Oligodendrocyte lineage gene-1 expressed in oligodendrocytes may trigger the repair of neuronal myelin impairment, and play a crucial role in myelin repair. Hypoxia-inducible factor la, a transcription factor, is of g...Oligodendrocyte lineage gene-1 expressed in oligodendrocytes may trigger the repair of neuronal myelin impairment, and play a crucial role in myelin repair. Hypoxia-inducible factor la, a transcription factor, is of great significance in premature infants with hypoxic-ischemic brain damage There is little evidence of direct regulatory effects of hypoxia-inducible factor le on oligodendrocyte lineage gene-l. In this study, brain slices of Sprague-Dawley rats were cultured and subjected to oxygen-glucose deprivation. Then, slices were transfected with hypoxia-inducible factor la or oligodendrocyte lineage gene-1. The expression levels of hypoxia-inducible factor la and oligodendrocyte lineage gene-1 were significantly up-regulated in rat brains prior to transfection, as detected by immunohistochemical staining. Eight hours after transfection of slices with hypoxia-inducible factor la, oligodendrocyte lineage gene-1 expression was upregulated, and reached a peak 24 hours after transfection. Oligodendrocyte lineage gene-1 transfection induced no significant differences in hypoxia-inducible factor la levels in rat brain tissues with oxygen-glucose deprivation. These experimental findings indicate that hypoxia-inducible factor la can regulate oligodendrocyte lineage gene-1 expression in hypoxic brain tissue, thus repairing the neural impairment.展开更多
This paper proposes the concept of inter-cell relay for downlink orthogonal frequency division multiple access(OFDMA) cellular systems, which uses multi-hop to relay calls from overloaded cells to light-load neighbori...This paper proposes the concept of inter-cell relay for downlink orthogonal frequency division multiple access(OFDMA) cellular systems, which uses multi-hop to relay calls from overloaded cells to light-load neighboring cells. It is shown that when using inter-cell relay, the number of calls in the congestion cell can be significantly increased. The congestion cell is divided into two parts. One is called non-relay area(NRA), in which a call directly communicates with the base station(BS) of a congested cell. The other is called relay area(RA), in which a call communicates with the BS of a neighboring cell through a relay station(RS). The two parts have different user-call densities. By adjusting the densities of two parts, we will maximize the number of supported calls inside a congested cell. The results show the benefits gained from inter-cell relay in congestion relief, which can reduce cell congestion by fully utilizing the available resources in the neighboring cells.展开更多
文摘In this study, Yangmeikeng mountain area with a long-term natural restoration status (communities 1, 2, and 3) and Chiao mountain area with an artificially disturbed status (communities 4 and 5) in Shenzhen in China were subjected to plant community composition and diversity statistical analysis on the basis of the following indices: plant height;density;tree layer DBH;coverage;number of family, genus, and species;calculated diversity indices;richness;similarity coefficients of family, genus and species;and species evenness. The diversity levels of each index in each community were compared, and the relationships of family, genus, and species in the communities with one another were determined. The integrated diversity levels in the two areas were also analyzed. Results showed that the composition status of three communities, especially communities 2 and 3, which were located at high elevation, in Yangmeikeng with the long-term natural restoration status was better. The diversity values were also evidently higher. The vegetation composition in Yangmeikeng was also greater than that in Chiao. The integration status of numerous diversity indices, such as evenness and richness, was higher than that of the latter. These data could be used as a basis for arguments regarding the status of natural and artificial forest biodiversities. Many species in the community in artificial forests were shrubs and herbs. The richness and proportion of tree species were distinctly low. Thus, shrubs and herbs were the main components of the artificial interference community. The number and richness of the tree species in natural or long-term natural restoration forests were higher than those of the former. The family diversity D<sub>f</sub> of the three communities in Yangmeikeng was slightly lower than that of the two communities in Chiao. By contrast, the genus diversity D<sub>g</sub>, family richness, and genus richness in Yangmeikeng were higher than those in Chiao. In terms of α-diversity and similarity coefficient, family, genus, and species were not directly related to one another. Therefore, species, genus, and family composition should be combined with their diversity status in the statistical and biodiversity analysis of a community. Synthetic diversity indices should be further analyzed to evaluate the diversity status of a community objectively.
文摘In this paper, a deep learning-based method is proposed for crowdcountingproblems. Specifically, by utilizing the convolution kernel densitymap, the ground truth is generated dynamically to enhance the featureextractingability of the generator model. Meanwhile, the “cross stage partial”module is integrated into congested scene recognition network (CSRNet) toobtain a lightweight network model. In addition, to compensate for the accuracydrop owing to the lightweight model, we take advantage of “structuredknowledge transfer” to train the model in an end-to-end manner. It aimsto accelerate the fitting speed and enhance the learning ability of the studentmodel. The crowd-counting system solution for edge computing is alsoproposed and implemented on an embedded device equipped with a neuralprocessing unit. Simulations demonstrate the performance improvement ofthe proposed solution in terms of model size, processing speed and accuracy.The performance on the Venice dataset shows that the mean absolute error(MAE) and the root mean squared error (RMSE) of our model drop by32.63% and 39.18% compared with CSRNet. Meanwhile, the performance onthe ShanghaiTech PartB dataset reveals that the MAE and the RMSE of ourmodel are close to those of CSRNet. Therefore, we provide a novel embeddedplatform system scheme for public safety pre-warning applications.
文摘From Jan</span><span style="font-family:Verdana;">.</span><span style="font-family:Verdana;"> 2013 to Nov</span><span style="font-family:Verdana;">.</span><span style="font-family:Verdana;"> 2018, we carried out the investigation on vegetation studies in the ecological monitoring programs, Shenzhen</span><span style="font-family:Verdana;"> and</span><span style="font-family:""><span style="font-family:Verdana;"> totally researched 170 plant communities of mountain areas etc., </span><span style="font-family:Verdana;">few areas of street regions and parks etc., for communities’ structural characteristics and plant diversity. We comparatively analyzed natural forests, semi-natural forest and artificial forest composition and structural characters and family, genus and species diversity level and the main affected factors. We also researched and analyzed these communities’ structural characteristics and pant diversity, </span><span style="font-family:Verdana;">comparatively analyzed natural forests, semi-natural forest and artificial forest composition and structural characters and family, genus and species diversity level, the main affected factors;researched and analyzed the relationship between plant community structure characteristics with the absorbing ability to PM</span><sub><span style="font-family:Verdana;">2.5</span></sub><span style="font-family:Verdana;"> pollutants. The result showed that the structure and plant diversity of natural </span><span style="font-family:Verdana;">forest </span></span><span style="font-family:Verdana;">were </span><span style="font-family:Verdana;">obviously better than</span><span style="font-family:Verdana;"> artificial disturbed forest or artificial forest, the semi-natural forest w</span><span style="font-family:Verdana;">as</span><span style="font-family:Verdana;"> the middle level of the forests, In the indices of height, DBH, coverage and crow width etc. of tree layer, natural forests and semi-natural forests were obvious higher than that of artificial disturbed forest or artificial forest;in some forests of artificial disturbed forest or artificial forest, though their richness indices of family and genus were a slightly higher, but this contribution was majorly due to herb layer plants, and some shrub layer plants. Analyz</span><span style="font-family:Verdana;">ing</span><span style="font-family:Verdana;"> three kinds of communities, the number of tree layer species of natural forest was</span><span style="font-family:Verdana;"> the </span><span style="font-family:""><span style="font-family:Verdana;">largest, and their every </span><i><span style="font-family:Verdana;">α</span></i><span style="font-family:Verdana;">-diversity index value was </span></span><span style="font-family:Verdana;">the </span><span style="font-family:Verdana;">highest;these characteristics values of semi-natural forest were second, artificial disturbed forests or artificial forests were </span><span style="font-family:Verdana;">the </span><span style="font-family:""><span style="font-family:Verdana;">lowest;in shrub layer, and herb layer, few </span><i><span style="font-family:Verdana;">α</span></i><span style="font-family:Verdana;">-diversity indices of artificial disturbed forest or artificial forest were </span><span style="font-family:Verdana;">a slightly higher than that of some natural forests, but the integral values of the diversity indices of natural forest and semi-natural forest were obvious</span></span><span style="font-family:Verdana;">ly</span><span style="font-family:Verdana;"> higher than the former. The research showed that in the artificial disturbed forest or artificial forest, because there have some little scale clearing area</span><span style="font-family:Verdana;">s</span><span style="font-family:""><span style="font-family:Verdana;">, so some pioneer plant species could enter the community and formed a temporarily </span><span style="font-family:Verdana;">increase of species diversity, however</span></span><span style="font-family:Verdana;">,</span><span style="font-family:Verdana;"> these species major </span><span style="font-family:Verdana;">were</span><span style="font-family:Verdana;"> some shrub and herb plants;but tree layer possessed obvious</span><span style="font-family:Verdana;">ly</span><span style="font-family:Verdana;"> more, even surpass</span><span style="font-family:Verdana;">ed</span><span style="font-family:Verdana;"> several ten times biomass than shrub and herb layers</span><span style="font-family:Verdana;">.</span><span style="font-family:Verdana;"> Therefore</span><span style="font-family:Verdana;">,</span><span style="font-family:Verdana;"> the respect</span><span style="font-family:Verdana;">s</span><span style="font-family:""><span style="font-family:Verdana;"> of maintain ecosystem stability and other</span><span style="font-family:Verdana;"> ecological efficient have </span><span style="font-family:Verdana;">major and dominated position and so on;and then this community can </span></span><span style="font-family:Verdana;">be </span><span style="font-family:Verdana;">natural recovery and succession, those forementioned new entire plants shall withdraw from the community and are replaced by the original plants of the community;but this process has already caused the ecological efficient loss and ecosystem unstable. Above research results are better evidence and theory reference to the argument problems on that </span><span style="font-family:Verdana;">are</span><span style="font-family:""><span style="font-family:Verdana;"> natural forest and natural restoration forest biodiversity higher? or is artificial forest biodiversity higher? and or is more artificial disturbed forest higher?</span><span style="font-family:Verdana;"> Our researches showed that used random investigation method set quadrats, and combined typical investigation method, the structural indices in the all layer of community and all diversity indices of tree, shrub and herb layers and the integral values </span></span><span style="font-family:Verdana;">were</span><span style="font-family:""><span style="font-family:Verdana;"> similar, same or usually these indices in the community which set 600 m</span><sup><span style="font-family:Verdana;">2</span></sup><span style="font-family:Verdana;">, 800 m</span><sup><span style="font-family:Verdana;">2</span></sup><span style="font-family:Verdana;"> total quatrat area were higher (</span><i><span style="font-family:Verdana;">α</span></i><span style="font-family:Verdana;">-diversity) than that of more than 3000 m</span><sup><span style="font-family:Verdana;">2</span></sup><span style="font-family:Verdana;">, 4000 m</span><sup><span style="font-family:Verdana;">2</span></sup><span style="font-family:Verdana;"> or 7000 m</span><sup><span style="font-family:Verdana;">2</span></sup><span style="font-family:Verdana;">, even more than 17,000 m</span><sup><span style="font-family:Verdana;">2</span></sup><span style="font-family:Verdana;"> total qua</span></span><span style="font-family:Verdana;">d</span><span style="font-family:Verdana;">rat area of communities. These lot</span><span style="font-family:Verdana;">s</span><span style="font-family:""><span style="font-family:Verdana;"> of researches further proved that according to minimum area method for vegetation survey, in subtropical region, using random investigation method combined with typical investigation set 400 m</span><sup><span style="font-family:Verdana;">2</span></sup><span style="font-family:Verdana;"> or 400 m</span><sup><span style="font-family:Verdana;">2</span></sup><span style="font-family:Verdana;"> - 500 m</span><sup><span style="font-family:Verdana;">2</span></sup><span style="font-family:Verdana;"> total qua</span></span><span style="font-family:Verdana;">d</span><span style="font-family:""><span
基金supported by the National Natural Science Foundation of China,No.81241022the Beijing Municipal Natural Science Foundation in China,No.7122045,7072023
文摘Oligodendrocyte lineage gene 1 plays a key role in hypoxic-ischemic brain damage and myelin repair, miRNA-9 is involved in the occurrence of many related neurological disorders. Bioin- formatics analysis demonstrated that miRNA-9 complementarily, but incompletely, bound oligodendrocyte lineage gene 1, but whether miRNA-9 regulates oligodendrocyte lineage gene 1 remains poorly understood. Whole brain slices of 3-day-old Sprague-Dawley rats were cultured and divided into four groups: control group; oxygen-glucose deprivation group (treatment with 8% O2 + 92% N2 and sugar-free medium for 60 minutes); transfection control group (after oxygen and glucose deprivation for 60 minutes, transfected with control plasmid) and miRNA-9 transfection group (after oxygen and glucose deprivation for 60 minutes, transfected with miRNA-9 plasmid). From the third day of transfection, and with increasing culture days, oligodendrocyte lineage gene 1 expression increased in each group, peaked at 14 days, and then decreased at 21 days. Real-time quantitative PCR results, however, demonstrated that oligoden- drocyte lineage gene 1 expression was lower in the miRNA-9 transfection group than that in the transfection control group at 1, 3, 7, 14, 21 and 28 days after transfection. Results suggested that miRNA-9 possibly negatively regulated oligodendrocyte lineage gene 1 in brain tissues during hypoxic-ischemic brain damage.
基金financial support from the National Natural Science Foundation of China (21773111, 21473089, 21573107 and 51571110)the National Key Research and Development Program of China (2017YFA0206503, 2018YFA0209103)+1 种基金Priority Academic Program Development of Jiangsu Higher Education Institutions, Fundamental Research Funds for the Central Universitiesthe program B for outstanding PhD candidate of Nanjing University (201702B049)
文摘Exploring inexpensive and efficient bifunctional electrocatalysts for oxygen reduction reaction(ORR) and oxygen evolution reaction(OER) is critical for rechargeable metal-air batteries. Herein, we report a new 3D hierarchical sulfur and nitrogen co-doped carbon nanocages(hSNCNC) as a promising bifunctional oxygen electrocatalyst by an in-situ MgO template method with pyridine and thiophene as the mixed precursor. The as-prepared h SNCNC exhibits a positive half-wave potential of 0.792 V(vs. reversible hydrogen electrode, RHE) for ORR, and a low operating potential of 1.640 V at a 10 mA cm-2 current density for OER. The reversible oxygen electrode index is 0.847 V, far superior to commercial Pt/C and IrO2,which reaches the top level of the reported bifunctional catalysts. Consequently, the hSNCNC as air cathodes in an assembled Zn-air battery features low charge/discharge overpotential and long lifetime. The remarkable properties arises from the introduced multiple heteroatom dopants and stable 3D hierarchical structure with multi-scale pores, which provides the abundant uniform high-active S and N species and efficient charge transfer as well as mass transportation. These results demonstrate the potential strategy in developing suitable carbon-based bi-/multi-functional catalysts to enable the next generation of the rechargeable metal-air batteries.
基金Financial provided by the National Key Research and Development Program of China (Grant No. 2017YFC0603001)the National Natural Science Foundation of China (Nos. 51734009 and 51704279)the Natural Science Foundation of Jiangsu Province (BK20170270)
文摘The mechanism of bolt support is an important topic in mining engineering and slope treatment. The artificial material and loading system were self-developed to study the influence of bedding cohesion and bolt number on the anchoring behavior of bedded rock mass. The results show that, both peak strength and elasticity modulus increase gradually with the increase of bedding cohesion and bolt number. The axial stress–strain curve of bedded rock mass under the reinforcement of bolts presents the features of strain-softening and secondary strengthening. Finally, anchoring behavior of bedded rock mass with different bolt numbers was simulated by using FLAC3 D numerical program and the results were compared with the experimental results. This study can provide certain bases to the stability control and support design of bedded rock mass in roadway.
基金supported by the National Natural Science Foundation of China(NSFC Project Nos.21776104,21476088)the National Key Research and Development Program of China(Project Nos.2016YFB0101201,2017YFB0102900)+1 种基金the Guangdong Provincial Department of Science and Technology(Project No.2015B010106012)the Guangzhou Science,Technology and Innovation Committee(Project Nos.201504281614372,2016GJ006)。
文摘Air cathodes with high electrocatalytic activity are vital for developing H2/O_(2) proton exchange membrane fuel cells(PEMFC)and Zn-air batteries.However,the state-of-the-art air cathodes suffer from either limited catalytic activity or high cost,which thus hinder their applications.Herein,we designed ZIF-8 derived nitrogen and atomic iron dual-doped porous carbon nanocubes as high-quality catalysts for ORR,through a novel gas-doping approach.The porous carbon nanocubic architecture and abundant Fe-Nxactive species endow ZIF-8 derived single atomic iron catalyst(PCN-A@Fe SA)with superior catalytic activity,and surpass Pt/C and a majority of the reported catalysts.Both XAS and DFT calculations suggest that Fe2+N4 moieties are the main active centers that are favorable for oxygen affinity and OH*intermediate desorption,which can result in promising catalytic performance.Most importantly,PCNA@Fe SA can achieve power density of 514 m W cm^(-2) as cathodic catalyst in a PEMFC and discharge peak power density of 185 m W cm^(-2) in an alkaline Zn-air battery.The outstanding performance is derived from both the high specific surface area and high-density of iron single atom in nitrogen doped nanocubic carbon matrix.
基金financially supported by the National Natural Science Foundation of China(Nos.51875401 and 52075376).
文摘The friction pull plug welding(FPPW)of the 2219-T87 tungsten inert gas(TIG)welded joint was investigated,and the microstructures,precipitate evolution,mechanical properties,and fracture morphologies of this joint were analyzed and discussed.In this study,defectfree joints were obtained using a rotational speed of 7000 r/min,an axial feeding displacement of 12 mm,and an axial force of 20-22 kN.The results indicated that within these welding parameters,metallurgical bonding between the plug and plate is achieved by the formation of recrystallized grains.The microstructural features of the FPPW joint can be divided into different regions,including the heat-affected zone(HAZ),thermomechanically affected zone(TMAZ),recrystallization zone(RZ),heat-affected zone in the TIG weld(TIG-HAZ),and the thermomechanically affected zone in the TIG weld(TIG-TMAZ).In the TIG-TMAZ,the grains were highly deformed and elongated due to the shear and the extrusion that produces the plug during the FPPW process.The main reason for the softening in the TMAZ is determined to be the dissolution ofθ’and coarsening ofθprecipitate particles.In a tensile test,the FPPW joint welded with an axial force of 22 kN showed the highest ultimate tensile strength of 237 MPa.The locations of cracks and factures in the TIG-TMAZ were identified.The fracture morphology of the tensile sample showed good plasticity and toughness of the joints.
文摘In this study,we investigated the hydrogen evolution reaction(HER)on the(101)facet of pristine and W-doped CoP using the density functional theory.Two types of Co atoms are identified on the catalyst surface:the Co atoms that present the higher d band center are marked as valid sites,whereas the others are marked as invalid sites owing to their weaker H adsorption ability.It is further revealed that W-doping can decrease the d band center of the surface Co atoms,which is beneficial for the HER;however the exposure to W weakens the desorption of H.To address the strong adsorption effect of W,the doping sites and dopant content are analyzed,and the results indicate that 8.4 wt%W doping at the invalid surface Co sites is preferred;moreover,the optimal W content increases to 16.8 wt%when W is inserted into the subsurface.The effect of W doping is weakened when the doping site is far away from the surface.
基金funded by National Natural Science Foundation of China grant No.11572046
文摘To improve the energy utilization efficiency of metal bridge foil explosion, and increase the function range of plasmas, array bridge foil explosion experiments with different structures were performed. A Schlieren photographic measurement system with a double-pulse laser source was used to observe the flow field of a bridge foil explosion. The evolution laws of plasmas and shock waves generated by array bridge foil explosions of different structures were analyzed and compared. A multi-phase flow calculation model was established to simulate the electrical exploding process of a metal bridge foil. The plasma equation of state was determined by considering the effect of the changing number of particles and Coulomb interaction on the pressure and internal energy. The ionization degree of the plasma was calculated via the Saha-Eggert equation assuming conditions of local thermal equilibrium. The exploding process of array bridge foils was simulated, and the superposition processes of plasma beams were analyzed. The variation and distribution laws of the density, temperature, pressure, and other important parameters were obtained. The results show that the array bridge foil has a larger plasma jet diameter than the single bridge foil for an equal total area of the bridge foil. We also found that the temperature, pressure, and density of the plasma jet's center region sharply increase because of the superposition of plasma beams.
文摘In this paper the atomization character of the pressure-swirl injector was measured by using the Phase Doppler Particle Analyzer (PDPA) in the section of 150 mm below the outlet of the orifice. The orifice diameter of the pressure-swirl injector is 0.62 mm. The atomization character includes the spray angle, the water flow rate, the Sauter mean diameter (SMD), the velocity of the particles and their distribution in the radial and the axial directions under the pressure from 1 MPa to 4.5 MPa. After that the atomization character of the pressure-swirl injector was simulated in the DPM panel. The same atomization character of the injector was calculated and compared with the experimental data. The simulation was corrected by using the experimental data which can make it accurately and the model can be used to predict and calculate the atomization character of different injectors.
文摘This study investigated multiple aspects of vulnerability to HIV in out-of-school adolescents and youth in Yunnan Province, a high HIV risk region in China. The findings show that socially disadvantaged adolescents and youth were overrepresented in the out-of-school young people in Yunnan. The out-of-school young people in Yunnan exhibited 1) limited knowledge about HIV transmission and prevention, 2) a high prevalence of unprotected sexual activity, 3) high exposure to illicit drugs and alcohol use and a high prevalence of drug use in themselves, and 4) limited access to health services. There is an indication of higher exposure to risk behaviours in the younger age group. The study population used multiple media, particularly television, internet and radio, to obtain information about HIV transmission and prevention, particularly in the younger age group. These media may be an effective way of reaching this population in future HIV education and prevention programs in the region.
基金Supported by Research Project of Zhumadian Branch of Henan Provincial Tobacco Company(201641170024101)。
文摘[Objective]The paper was to study the relationship between spatial distribution characteristics of soil p H and bacterial wilt in tobacco-growing area in Henan Province.[Method]The 21 tobacco-growing fields infected by bacterial wilt and 91 tobacco-growing fields with no cases were selected from Henan Province,and the pH of fields was determined.[Result]Bacterial wilt mainly occurred in the tobacco-growing fields in Luoshan,Pingqiao,Queshan,Biyang,Suiping,and Xiping,and the soil pH mainly ranged from 5.5 to 6.5(accounted for 84.75%of total surveyed tobacco fields);bacterial wilt had not been found in tobacco-growing fields in Tanghe,Zhengyang,Shangcai,Sheqi,Wuyang and Chenqu,and the soil pH mainly ranged from 6.5 to 7.0(accounted for 81.25%of total surveyed tobacco fields).There were significant differences in soil pH between the fields with and without bacterial wilt,and soil pH 6.5 could be regarded as the threshold for the occurrence of tobacco bacterial wilt in Henan Province.There was extremely significantly positive linear correlation between soil p H and latitude(y=0.7375 x-17.799,R2=0.386,P<0.01).The geographical boundary of soil pH 6.5 was roughly 33°N,and bacterial wilt was less likely to occur in the north tobacco-growing areas of the boundary.[Conclusion]The study will provide a scientific basis for the prevention and control of tobacco bacterial wilt in Henan.
基金supported by the National Natural Science Foundation of China,No. 81241022the Natural Science Foundation of Beijing,No. 7072023,7122045
文摘Oligodendrocyte lineage gene-1 expressed in oligodendrocytes may trigger the repair of neuronal myelin impairment, and play a crucial role in myelin repair. Hypoxia-inducible factor la, a transcription factor, is of great significance in premature infants with hypoxic-ischemic brain damage There is little evidence of direct regulatory effects of hypoxia-inducible factor le on oligodendrocyte lineage gene-l. In this study, brain slices of Sprague-Dawley rats were cultured and subjected to oxygen-glucose deprivation. Then, slices were transfected with hypoxia-inducible factor la or oligodendrocyte lineage gene-1. The expression levels of hypoxia-inducible factor la and oligodendrocyte lineage gene-1 were significantly up-regulated in rat brains prior to transfection, as detected by immunohistochemical staining. Eight hours after transfection of slices with hypoxia-inducible factor la, oligodendrocyte lineage gene-1 expression was upregulated, and reached a peak 24 hours after transfection. Oligodendrocyte lineage gene-1 transfection induced no significant differences in hypoxia-inducible factor la levels in rat brain tissues with oxygen-glucose deprivation. These experimental findings indicate that hypoxia-inducible factor la can regulate oligodendrocyte lineage gene-1 expression in hypoxic brain tissue, thus repairing the neural impairment.
基金National Natural Science Foundation of China under grant number (61872186,61872193)The National Natural Science Foundation of China for Youth (61201160, 61602263)+8 种基金The Natural Science Foundation of Jiangsu Province (BK20131377, BK20151507, BK20160916)The Natural science fund for colleges and universities in Jiangsu Province under Grants (16KJB510034)The six talent peaks project in Jiangsu Province (XYDXXJS-044)A Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions (yx002001)The Jiangsu Overseas Research and Training Program for University Prominent Young and Middle-aged Teachers and PresidentsSponsored by NUPTSF (Grant Nos. NY212012, NY214065,NY216020)The Six Talented Eminence Foundation of Jiangsu Province (No. XYDXXJS-044)The 333 High-level Talents Training Project of Jiangsu ProvinceThe 1311 Talents Plan of NUPT and the China Postdoctoral Science Foundation (No. 2018M630590)
文摘This paper proposes the concept of inter-cell relay for downlink orthogonal frequency division multiple access(OFDMA) cellular systems, which uses multi-hop to relay calls from overloaded cells to light-load neighboring cells. It is shown that when using inter-cell relay, the number of calls in the congestion cell can be significantly increased. The congestion cell is divided into two parts. One is called non-relay area(NRA), in which a call directly communicates with the base station(BS) of a congested cell. The other is called relay area(RA), in which a call communicates with the BS of a neighboring cell through a relay station(RS). The two parts have different user-call densities. By adjusting the densities of two parts, we will maximize the number of supported calls inside a congested cell. The results show the benefits gained from inter-cell relay in congestion relief, which can reduce cell congestion by fully utilizing the available resources in the neighboring cells.