检索结果-南通市图书馆

Arsenate biotransformation by Microcystis aeruginosa under different nitrogen and phosphorus levels

在线全文

学校读者我要写书评

暂无评论

Journal of Environmental Sciences 2018年第4期30卷 41-49页

作者： Feifei che Miaomiao Du Changzhou Yan Key Laboratory of Urban Environment and Health Institute of Urban Environment Chinese Academy of Sciences

The arsenate（As（V）） biotransformation by Microcystis aeruginosa in a medium with different concentrations of nitrogen（N） and phosphorus（P） has been studied under laboratory conditions. When 15 μg/L As（V） was added, N and P in the medium showed effective regulation on arsenic（As） metabolism in M. aeruginosa, resulting in significant differences in the algal growth among different N and P treatments. Under 0.2 mg/L P treatment, increases in N concentration（4–20 mg/L） significantly stimulated the cell growth and therefore indirectly enhanced the production of dimethylarsinic acid（DMA）, the main As metabolite, accounting for 71%–79% of the total As in the medium. Meanwhile, 10–20 mg/L N treatments accelerated the ability of As metabolization by M. aeruginosa, leading to higher contents of DMA per ***, As（V） uptake by M. aeruginosa was significantly impeded by 0.5–1.0 mg/L P treatment,resulting in smaller rates of As transformation in M. aeruginosa as well as lower contents of As metabolites in the medium. Our data demonstrated that As（V） transformation by M. aeruginosa was significantly accelerated by increasing N levels, while it was inhibited by increasing P levels. Overall, both P and N play key roles in As（V） biotransformation processes.

关键词： Arsenate Biotransformation Nitrogen Phosphorus M.aeruginosa

Evaluation on the state of sand filling layer and the influence on segment deformation of immersed tunnels

在线全文

学校读者我要写书评

暂无评论

Underground Space 2024年第3期16卷 224-238页

作者： Ziyao Xu Ailan che Chao Su School of Naval Architecture Ocean and Civil EngineeringShanghai Jiao Tong UniversityShanghai 200240China CCCC Second Harbor Engineering Company Ltd. Wuhan 430040China

The immersed tunnel is considered an effective solution for traffic problems across rivers and *** sand filling layer,as an important part of immersed tunnel foundation treatments,directly affects segment attitude *** to difficulties in quality control of concealed construction and the complex hydrodynamic environment,the sand filling layer is prone to compaction defects,further leading to changes in segment ***,limited by structural concealment and state complexity,most studies consider the sand filling layer part of the foundation to study its impact on settlement while neglecting its influence on segment *** research proposes an evaluation method for the sand filling layer state based on elastic wave testing and the elastic wave characteristic parameters selected come from analysis of the time domain,frequency domain and time–frequency *** classifying the elastic wave characteristic parameters through the K-means clustering method,the relationship between the state of the sand filling layer and the elastic wave characteristic parameters is *** state of the sand filling layer is divided into dense,incompact,and void.A numerical model is established based on the Guangzhou BI-UT immersed tunnel with incompact and void sand filling layer states to simulate deformation and *** results indicate that the settlement of the tunnel segment is low in the eastern region and high in the western region due to the presence of a less dense sand filling layer,with a maximum differential settlement of 0.04 *** evaluation method plays a crucial role in guiding the construction of immersed tube tunnels.

关键词： Sand filling layer state Immersed tunnel Elastic wave test Clustering algorithm

Parameter selection in time series prediction based on nu-support vector regression

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

High Technology Letters 2009年第4期15卷 337-342页

作者：胡亮 che Xilong College of Computer Science and Technology Jilin University Changchun 130012 P. R. China

The theory of nu-support vector regression (Nu-SVR) is employed in modeling time series variationfor prediction. In order to avoid prediction performance degradation caused by improper parameters, themethod of parallel multidimensional step search (PMSS) is proposed for users to select best parameters intraining support vector machine to get a prediction model. A series of tests are performed to evaluate themodeling mechanism and prediction results indicate that Nu-SVR models can reflect the variation tendencyof time series with low prediction error on both familiar and unfamiliar data. Statistical analysis is alsoemployed to verify the optimization performance of PMSS algorithm and comparative results indicate thattraining error can take the minimum over the interval around planar data point corresponding to selectedparameters. Moreover, the introduction of parallelization can remarkably speed up the optimizing procedure.

关键词： parameter selection time series prediction nu-support vector regression (Nu-SVR) parallel multidimensional step search (PMSS)

Periodic DFT study on the structural and thermal properties of bulk anti-fluorite magnesium silicide

在线全文

学校读者我要写书评

暂无评论

Acta Metallurgica Sinica(English Letters) 2011年第4期24卷 271-280页

作者： Dong che Feng PENG Benhai Yu Cohege of Physics and Electronic Engineering Xinyang Normal University Xinyang 464000 China College of Physics and Electronic Information Luoyang Normal University Luoyang 471022 China

The structural and thermoelasticity of antifluorite magnesium silicide at high temper- atures were studied by using the plane-wave pseudo-potential method in the frame- work of density functional theory. The bulk ground-state quantities such as lattice constants, cell volumes, band structures and elastic constants were calculated. It showed that the elastic constants of Mg2Si were well consistent with the experimen- tal data under ambient conditions. The crystal cell volume and bulk modulus of Mg2Si as functions of applied temperature were also presented. The lattice dynamics was applied to determine the phonon dispersion curves. To complete the fundamental characterisation of this crystal, the coefficients of thermal expansion （CTE）, isochoric heat capacities and Debye temperature of Mg2Si in the whole temperature range from 0 K to 1300 K and pressure range from 0 GPa to 7.48 GPa were investigated. The results were in favourable agreement with the previous theoretical calculations and the existing experimental data.

关键词： Mg2Si Phonon distribution Mechanical properties Latticedynamics

Signal difference-based deadband H_∞ control approach for networked control systems with limited resources

在线全文

学校读者我要写书评

暂无评论

Journal of Systems Engineering and Electronics 2015年第3期26卷 573-583页

作者： Yingying Liu Weiwei che Yunkai Chu School of Information Engineering Shenyang University Key Laboratory of Manufacturing Industrial Integrated Automation Shenyang University Shenyang Institute of Automation Chinese Academy of Sciences

This paper investigates a signal difference-based dead- band H∞ control approach for networked control systems （NCSs） with limited resources. The effects of variable network-induced de- lays, sampling intervals and data transmitting deadbands are con- sidered simultaneously and the model of the NCS is presented. A Lyapunov functional is adopted, which makes full use of the network characteristic information including the bounds of net- work delay （BND）, the bounds of sampling interval （BSI） and the bounds of transmission deadband （BTD）. In the meanwhile, the new H∞ performance analysis and controller design conditions for the NCSs are proposed, which describe the relationship of BND, BSI, BTD and the system＇s performance. Three examples are used to illustrate the advantages of the proposed methods. The results have shown that the proposed method not only effectively reduces the data traffic, but also guarantees the system asymptotically sta- ble and achieves the prescribed H∞ disturbance attenuation level.

关键词： networked control system (NCS) H∞ control vari-able network-induced delay variable sampling interval transmission deadband.

Coupling Effects of A Deep-Water Drilling Riser and the Platform and the Discharging Fluid Column in An Emergency Disconnect Scenario

在线全文

学校读者我要写书评

暂无评论

China Ocean Engineering 2020年第1期34卷 21-29页

作者： MENG Shuai cheN Yong che Chi-dong State Key Laboratory of Ocean Engineering Collaborative Innovation Center for Advanced Ship and Deep-sea ExplorationShanghai Jiao Tong UniversityShanghai 200240China Shanghai Marine Diesel Engine Research Institute Shanghai 200240China

As drilling operations move into remote locations and extreme water depths, recoil analysis requires more careful considerations and the incidence of emergency disconnect is increased inevitably. To accurately capture the recoil dynamics of a deep-water riser in an emergency disconnect scenario, researchers typically focus on modelling the influential subsystems (e.g., the tensioner, the mud discharge and seawater refilling process) which can be solved in the preprocessing, and then the determined parameters are transmitted into an existing global riser analysis software. Distinctively, the current study devotes efforts into the coupling effects resulting from that the suspended riser reacts the platform heave motion via the tensioner system in the course of recoil and the discharging fluid column follows the oscillation of the riser in the mud discharge process. Four simulation models are established based on lumped mass method employing different formulas for the top boundary condition of the riser and the discharging flow acceleration. It demonstrates that the coupling effects discussed above can significantly affect the recoil behavior during the transition phase from initial disconnect to the final hang-off state. It is recommended to develop a fully- coupled integrated model for recoil analysis and anti-recoil control system design before extreme deep-water applications.

关键词： recoil analysis emergency disconnect coupling effect platform excitation

Primary frequency response based rescheduling for enhancing microgrid resilience

在线全文

学校读者我要写书评

暂无评论

Journal of Modern Power Systems and Clean Energy 2019年第4期7卷 696-704页

作者： Liang che Xinwei SHEN Mohammad SHAHIDEHPOUR Hunan University Changsha 410082China Tsinghua-Berkeley Shenzhen Institute Shenzhen 518055China Illinois Institute of Technology ChicagoIL 60616USA

The existing microgrid operation schemes do not consider the dynamic performance of frequency in the islanded operation of *** an islanded microgrid encounters a disturbance,the sudden power mismatch could impose security risks or even a system *** address such a challenge,this paper proposes the primary frequency response rescheduling(PFRR)*** a certain operation interval,the PFRR will optimally reschedule the distributed generators(DGs)with non-zero mechanical inertia and adjust the battery *** the objective is to limit the rate-of-change-of-frequency(ROCOF)and to maintain the post-disturbance frequency nadir above a prescribed *** effectiveness of the proposed strategy is verified by a case study on the IEEE 123-node test feeder system and the timedomain simulation in MATLAB Simulink.

关键词： Microgrid Inertia Frequency control Primary frequency response Resilience

How little is known about “the little brown frogs”:description of three new species of the genus Leptobrachella(Anura:Megophryidae)from Yunnan Province, China

在线全文

学校读者我要写书评

暂无评论

Zoological Research 2020年第3期41卷 292-313页

作者： jin-Min chen Kai Xu Nikolay A.Poyarkov Kai Wang Zhi-Yong Yuan Mian Hou Chatmongkon Suwannapoom Jian Wang jing che State Key Laboratory of Genetic Resources and Evolution Kunming Institute of ZoologyChinese Academy of SciencesKunmingYunnan 650223China Southeast Asia Biodiversity Research Institute Chinese Academy of SciencesYezinNay Pyi Taw 05282Myanmar Kunming College of Life Science University of the Chinese Academy of SciencesKunmingYunnan 650204China Department of Vertebrate Zoology Biological FacultyLomonosov Moscow State UniversityMoscow 119991Russia Joint Russian-Vietnamese Tropical Research and Technological Center Nghia DoCau GiayHanoiVietnam Sam Noble Oklahoma Museum of Natural History&Department of Biology University of oklahomaNormanOklahoma 73072USA Key Laboratory for Conserving Wildlife with Small Populations in Yunnan Southwest Forestry UniversityKunmingYunnan 650224China College of Continuing(Online)Education Sichuan Normal UniversityChengduSichuan 610068China School of Agriculture and Natural Resources University of PhayaoPhayao 56000Thailand College of Life Science and Technology Honghe UniversityMengziYunnan 661199China

Asian leaf-litter toads of the genus Leptobrachella represent a great anuran diversification in *** studies have suggested that the diversity of this genus is still underestimated. During herpetological surveys from 2013 to 2018, a series of Leptobrachella specimens were collected from the international border areas in the southern and western parts of Yunnan Province, *** analyses based on morphological and molecular data revealed three distinct and previously unknown lineages, which we formally describe as three new species herein. Among them, we describe a new species that occurs at the highest known elevation for Leptobrachella in China. Four species of Leptobrachella, including two new species, are found in the same reserve. Furthermore, our results suggest that the population from Longchuan County,Yunnan, may represent an additional new species of Leptobrachella, although we tentatively assigned it to Leptobrachella cf. yingjiangensis due to the small sample size examined. Lastly, we provide the first description of females of L. yingjiangensis. Our results further highlight that both micro-endemism and sympatric distributions of species are common patterns in Leptobrachella, that contribute to taxonomic and conservation challenges in these frogs. We provide an identification key for Leptobrachella known to occur in Yunnan. Given the lack of knowledge on species diversity of Leptobrachella along international border areas, we recommend that future studies include transboundary collaborative surveys.

关键词： Biodiversity hotspot Conservation Cryptic diversity Micro-endemism National border Speciation Taxonomy

Cell replacement with stem cell-derived retinal ganglion cells from different protocols

在线全文

学校读者我要写书评

暂无评论

Neural Regeneration Research 2024年第4期19卷 807-810页

作者： Ziming Luo Kun-che Chang Spencer Center for Vision Research Byers Eye InstituteStanford University School of Medicine Department of Ophthalmology Louis J.Fox Center for Vision RestorationUniversity of Pittsburgh School of Medicine Department of Neurobiology Center of NeuroscienceUniversity of Pittsburgh School of Medicine

Glaucoma,characterized by a degenerative loss of retinal ganglion cells,is the second leading cause of blindness *** is currently no cure for vision loss in glaucoma because retinal ganglion cells do not regenerate and are not replaced after *** stem cell-derived retinal ganglion cell transplant is a potential therapeutic strategy for retinal ganglion cell degenerative *** this review,we first discuss a 2D protocol for retinal ganglion cell differentiation from human stem cell culture,including a rapid protocol that can generate retinal ganglion cells in less than two weeks and focus on their transplantation ***,we discuss using 3D retinal organoids for retinal ganglion cell transplantation,comparing cell suspensions and *** review provides insight into current knowledge on human stem cell-derived retinal ganglion cell differentiation and transplantation,with an impact on the field of regenerative medicine and especially retinal ganglion cell degenerative diseases such as glaucoma and other optic neuropathies.

关键词： cell clumps cell suspension cell transplantation differentiation direct-induced protocol glaucoma optic neuropathy regenerative medicine retinal ganglion cell retinal organoids stem cells