检索结果-南通市图书馆

Anisotropic turbulence of kinetic Alfvén waves and heating in solar corona

在线全文

学校读者我要写书评

暂无评论

Research in Astronomy and Astrophysics 2019年第12期19卷 327-342页

作者： Hemam Dinesh singh Bheem singh Jatav Department of Physics Sikkim University

Understanding solar coronal heating has been one of the unresolved problems in solar physics in spite of the many theories that have been developed to explain it. Past observational studies suggested that kinetic Alfven waves(KAWs) may be responsible for solar coronal heating by accelerating the charged particles in solar plasma. In this paper, we investigated the transient dynamics of KAWs with modified background density due to ponderomotive force and Joule heating. A numerical simulation based on pseudospectral method was applied to study the evolution of KAW magnetic coherent structures and generation of magnetic turbulence. Using different initial conditions in simulations, the dependence of KAW dynamics on the nature of inhomogeneous solar plasma was thoroughly investigated. The saturated magnetic power spectra follow Kolmogorov scaling of k^-5/3 in the inertial range, then followed by steep anisotropic scaling in the dissipation range. The KAW has anisotropy of k||∝ k^0.53⊥, k|| ∝ k^0.50⊥, k||∝ k^0.83⊥ and k||∝ k^0.30⊥ depending on the kind of initial conditions of inhomogeneity. The power spectra of magnetic field fluctuations showing the spectral anisotropy in wavenumber space indicate that the nonlinear interactions may be redistributing the energy anisotropically among higher modes of the wavenumber. Therefore, anisotropic turbulence can be considered as one of the candidates responsible for the particle energization and heating of the solar plasmas.

关键词： plasmas turbulence waves Sun:corona

Novel microbial fuel cell design to operate with different wastewaters simultaneously

在线全文

学校读者我要写书评

暂无评论

Journal of Environmental Sciences 2016年第4期28卷 105-111页

作者： Abhilasha singh Mathuriya Department of Biotechnology Anand Engineering College

A novel single cathode chamber and multiple anode chamber microbial fuel cell design（MAC-MFC）was developed by incorporating multiple anode chambers into a single unit and its performance was *** 60 days of operation,performance of MAC-MFC was assessed and compared with standard single anode/cathode chamber microbial fuel cell（SC-MFC）.The tests showed that MAC-MFC generated stable and higher power outputs compared with SC-MFC and each anode chamber contributed ***,MAC-MFCs were incorporated with different wastewaters in different anode chambers and their behavior in MFC performance was ***-MFC efficiently treated multiple wastewaters simultaneously at low cost and small space,which claims its candidature for future possible scale-up applications.

关键词： Microbial fuel cells Multiple wastes Bioelectricity New design Wastewater treatment

Soil Carbon Dynamics Under Changing Climate A Research Transition from Absolute to Relative Roles of Inorganic Nitrogen Pools and Associated Microbial Processes:A Review

在线全文

学校读者我要写书评

暂无评论

Pedosphere 2017年第5期27卷 792-806页

作者： pratap srivastava rishikesh singh sachchidanand tripathi pardeep singh shikha singh hema singh akhilesh singh raghubanshi pradeep kumar mishra department of chemical engineering and technology indian institute of technologybanaras hindu universityVaranasi 221005(India) institute of environment&sustainable development(iesd) banaras hindu universityVaranasi 221005(India) department of botany deen dayal upadhyaya collegeuniversity of delhiNew Delhi 110015(India) department of environmental studies pannalal girdharlal dayanand anglo-vedic collegeuniversity of delhiNew Delhi 110065(India) ecosystems analysis laboratory department of botanyinstitute of sciencebanaras hindu universityVaranasi 221005(India)

It is globally accepted that soil carbon （C） dynamics are at the core of interlinked environmental problems, deteriorating soil quality and changing climate. Its management remains a complex enigma for the scientific community due to its intricate relationship with soil nitrogen （N） availability and moisture-temperature interactions. This article reviews the management aspects of soil C dynamics in light of recent advances, particularly in relation to the availability of inorganic N pools and associated microbial processes under changing climate. Globally, drastic alterations in soil C dynamics under changing land use and management practices have been primarily attributed to the variation in soil N availability, resulting in a higher decomposition rate and a considerable decline in soil organic C （SOC） levels due to increased soil CO2 emissions, degraded soil quality, and increased atmospheric CO2 concentrations, leading to climate warming. Predicted climate warming is proposed to enhance SOC decomposition, which may further increase soil N availability, leading to higher soil CO2 effiux. However, a literature survey revealed that soil may also act as a potential C sink, if we could manage soil inorganic N pools and link microbial processes properly. Studies also indicated that the relative, rather than the absolute, availability of inorganic N pools might be of key importance under changing climate, as these N pools are variably affected by moisture-temperature interactions, and they have variable impacts on SOC turnover. Therefore, multi-factorial studies are required to understand how the relative availability of inorganic N pools and associated microbial processes may determine SOC dynamics for improved soil C management.

关键词： agro-management immobilization NH4+-N to NO3-N ratio nitrification relative availability soil C02 effiux

Investigation of microstructure and mechanical properties of friction stir welded AZ61 magnesium alloy joint

在线全文

学校读者我要写书评

暂无评论

Journal of Magnesium and Alloys 2018年第3期6卷 292-298页

作者： Kulwant singh Gurbhinder singh Harmeet singh I.K.Gujral Punjab Technical University KapurthalaPunjabIndia Guru Kashi University Talwandi SaboPunjabIndia

Increasing global demands for energy conservation and environmental protection led to the replacement of heavy components with lighter *** magnesium alloys are believed to be unique candidates for lightweight applications and friction stir welding(FSW)is capable of joining magnesium alloys,in the current work,FSW joint of AZ61 Mg alloy has been *** and mechanical properties of the joints were *** elongated grains of the base metal were recrystallized in the stir zone and in transition zone during friction stir *** formation of finer grains in the stir zone of the joint is responsible for increase the hardness of the stir *** microhardness of base metal is higher than that of thermo-mechanically affected zone but lower than that of stir *** tensile strength of the weld was about 82%of the as-received base *** joint failed in ductile *** ductile failure of joint was due to the uniform deformation of material.

关键词： Magnesium alloy Friction stir welding Stir zone Microhardness Microstructure AZ61

Bianchi type V universe with bulk viscous matter and time varying gravitational and cosmological constants

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

Research in Astronomy and Astrophysics 2012年第11期12卷 1457-1466页

作者： Prashant singh Baghel Jagdish Prasad singh Department of Mathematical Sciences A. P. S. University

We consider spatially homogeneous and anisotropic Bianchi type V space- time with a bulk viscous fluid source, and time varying gravitational constant G and cosmological term A. The coefficient of bulk viscosity ζ is assumed to be a simple linear function of the Hubble parameter H （i.e. ζ = ζ0 ＋ ζ1H, where ζ0 and ζ1 are constants）. The Einstein field equations are solved explicitly by using a law of varia- tion for the Hubble parameter, which yields a constant value of the deceleration pa- rameter. Physical and kinematical parameters of the models are discussed. The models are found to be compatible with the results of astronomical observations.

关键词： bulk viscosity -- Bianchi V -- relativity: equation of state -- cosmology:cosmological parameters -- miscellaneous

Review on friction stir welding of magnesium alloys

在线全文

学校读者我要写书评

暂无评论

Journal of Magnesium and Alloys 2018年第4期6卷 399-416页

作者： Kulwant singh Gurbhinder singh Harmeet singh I.K.Gujral Punjab Technical University KapurthalaPunjabIndia Guru Kashi University Talwandi SaboPunjabIndia

Friction Stir Welding(FSW)is considered to be the most significant development in metal joining in last two *** has many advantages when welding magnesium or lightweight *** Friction stir welding of magnesium alloy has many potential applications in major industries *** transportation,aerospace,railway,shipbuilding and marine,construction,and many other industrial *** magnesium alloys have been used in industrial equipment of nuclear energy as magnesium alloys have low tendency to absorb neutrons,sufficient resistance to carbon dioxide and excellent thermal ***,the research and development in FSW field and associated technologies have been developing rapidly *** this review article,the basic principle of friction stir welding and several aspects of friction stir welded magnesium alloys have been *** current state of friction stir welding of magnesium alloys is *** spite of this,much remains to be learned about the process and opportunities for further research are identified.

关键词： FSW Tool Geometry Stir Zone Mg Alloy Texture Microhardness.

Spatio-temporal evaluation of Zr plasma parameters in a single-beam-splitting double-pulse laser-induced plasma

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

Plasma Science and Technology 2021年第2期23卷 47-56页

作者： Arnab SARKAR Manjeet singh Fuel Chemistry Division Bhabha Atomic Research CentreMumbai 400085India Homi Bhabha National Institute AnushaktinagarMumbai 400094India

The plasma shielding effect is one of the major weaknesses of laser-induced breakdown spectroscopy(LIBS)as it causes non-linearity in signal *** LIBS is typically carried out in constant laser energy,this non-linearity causes a reduction in *** this work,we systematically examine laser-induced plasma,formed by two different excitation source modes,*** pulse(SP)-excitation and single-beam-splitting double-pulse(SBS-DP)-excitation over Zr-2.5%Nb *** two most important plasma parameters influencing the emission line intensity,plasma temperature(Te)and electron density(Ne)were studied and compared for both modes of laser *** of the results conclusively demonstrates that due to the splitting of the laser energy in the SBS-DP mode,the plasma shielding effect is significantly *** reduced plasma shielding translates to an increased laser–sample coupling under SBS-DP *** imaging of the total intensity of the laser-induced plasma in both excitation modes was also *** study shows how the plasma shielding effect can be reduced to improve the analytical quality of the LIBS methodology.

关键词： LIBS single-beam-splitting double pulse spatial-temporal evolution plasma temperature electron density

Development of mix design method based on statistical analysis of different factors for geopolymer concrete

在线全文

学校读者我要写书评

暂无评论

Frontiers of Structural and Civil Engineering 2022年第10期16卷 1315-1335页

作者： Paramveer singh Kanish KAPOOR Department of Civil Engineering Dr B R Ambedkar National Institute of TechnologyJalandhar 144011India

The present study proposes the mix design method of Fly Ash(FA)based geopolymer concrete using Response Surface Methodology(RSM).In this method,different factors,including binder content,alkali/binder ratio,NS/NH ratio(sodium silicate/sodium hydroxide),NH molarity,and water/solids ratio were considered for the mix design of geopolymer *** 2D contour plots were used to setup the mix design method to achieve the target compressive *** proposed mix design method of geopolymer concrete is divided into three categories based on curing regime,specifically one ambient curing(25°C)and two heat curing(60 and 90°C).The proposed mix design method of geopolymer concrete was validated through experimentation of M30,M50,and M70 concrete mixes at all curing *** observed experimental compressive strength results validate the mix design method by more than 90%of their target ***,the current study concluded that the required compressive strength can be achieved by varying any factor in the mix *** addition,the factor analysis revealed that the NS/NH ratio significantly affects the compressive strength of geopolymer concrete.

关键词： geopolymer concrete mix design fly ash response surface methodology compressive strength stress—strain

同方期刊数据库

Coherent structures and spectral shapes of kinetic Alfvén wave turbulence in solar wind at 1 AU

在线全文

学校读者我要写书评

暂无评论

Research in Astronomy and Astrophysics 2019年第7期19卷 33-46页

作者： Hemam Dinesh singh Bheem singh Jatav Department of Physics Sikkim University

This paper presents the generation of kinetic Alfv én wave(KAW) coherent structures of magnetic filaments applicable to solar wind at 1 AU,when the background plasma density is modified by parallel ponderomotive force and Joule *** inhomogeneity in the magnetic field,which was included as a perturbation in the transverse direction of the magnetic field,takes energy from the main pump KAWs and generates the filamentary *** the intensity is high enough,the filaments are broken down and the energy initially confined to low wavenumbers is redistributed to higher wavenumbers,leading to cascades of energy at small scales less than the ion acoustic gyroradius or comparable to electron *** magnetic field spectral profile is generated from the numerical simulation results,and its dependence on different directions of the wavevector and initial conditions of the simulation representing the transverse magnetic field inhomogeneity is *** relevance of these results with other spacecraft observations and measurements is also pointed out.

关键词： plasmas turbulence waves solar wind