检索结果-南通市图书馆

Teleparallel Killing Vectors of Spherically Symmetric Spacetimes

在线全文

学校读者我要写书评

暂无评论

Communications in Theoretical Physics 2009年第9期52卷 435-440页

作者： M.sharif Bushra Majeed Department of Mathematics University of the Punjab

In this paper, Killing vectors of spherically spacetimes have been evaluated in the context of teleparallel theory of gravitation. Further, we investigate the Killing vectors of the Friedmann metrics. It is found that for static spherically spacetimes the number of Killing vectors turns out to be seven while for the Friedmann models, we obtain six teleparallel Killing vectors. The results are then compared with those of General Relativity. We conclude that both of these descriptions of gravity do not provide the consistent results in general. However, these results may coincide under certain conditions for a particular spacetime.

关键词： teleparallel theory Killing vectors

Dark Energy Models and Cosmic Acceleration with Anisotropic Universe in f(T) Gravity

在线全文

学校读者我要写书评

暂无评论

Communications in Theoretical Physics 2014年第4期61卷 482-490页

作者： M.sharif Sehrish Azeem Department of Mathematics University of the PunjabQuaid-e-Azam Campus

This paper is devoted to studing the accelerated expansion of the universe in context of f（T） theory of gravity. For this purpose, we construct different f（T） models and investigate their cosmological behavior through equation of state parameter by using holographic, new agegraphic and their power-law entropy corrected dark energy models. We discuss the graphical behavior of this parameter versus redshif~ for particular values of constant parameters in Bianchi type I universe model. It is shown that the universe lies in different forms of dark energy, namely quintessence, phantom, and quintom corresponding to the chosen scale factors, which depend upon the constant parameters of the models.

关键词： f(T) gravity equation of state dark energy models

Singularities of noncompact charged objects

在线全文

学校读者我要写书评

暂无评论

Chinese Physics B 2013年第3期22卷 192-195页

作者： M.sharif G.Abbas Department of Mathematics University of the PunjabQuaid-e-Azam CampusLahore-54590Pakistan

We formulate a model for noncompact spherical charged objects in the framework of noncommutative field *** Einstein-Maxwell field equations are solved with charged anisotropic *** choose matter and charge densities as functions of the two parameters,instead of defining these quantities in terms of the Gaussian distribution *** is found that the corresponding densities and the Ricci scalar are singular in origin,whereas the metric is nonsingular,indicating a spacelike *** numerical solution of the horizon equation implies that there are two or one or no horizon（s）,depending on the *** also evaluate the Hawking temperature and find that a black hole with two horizons is evaporated to an extremal black hole with one horizon.

关键词： noncommutative geometry electromagnetic field spacetime singularity

Effects of thermal fluctuations on the Kerr–Newman–NUT–AdS black hole

在线全文

学校读者我要写书评

暂无评论

Communications in Theoretical Physics 2021年第8期73卷 114-123页

作者： M sharif Qanitah Ama-Tul-Mughani Department of Mathematics University of the PunjabQuaid-e-Azam CampusLahore-54590Pakistan

This paper is devoted to studying the impact of thermal fluctuations on thermodynamics of rotating as well as charged anti-de Sitter black holes with the Newman–Unti–Tamburino(NUT)*** this end,we derive the analytic expression of thermodynamic variables,namely the Hawking temperature,volume,angular velocity,and entropy within the limits of extended phase *** variables meet the first law of thermodynamics as well as the Smarr relation in the presence of new NUT *** analyze the effects of quantum fluctuations,we derive the exact expression of corrected entropy,which yields modification in other thermodynamical equations of *** local stability and phase transition of the considered black hole are also examined through specific *** is found that the NUT parameter increases the stability of small black holes,while the logarithmic corrections induce instability in the system.

关键词： black hole thermal fluctuations thermodynamics NUT parameter

User activities and the heteroseneity of urban space:The case of Dahiyat Al Hussein park

在线全文

学校读者我要写书评

暂无评论

Frontiers of Architectural Research 2020年第4期9卷 837-857页

作者： Ahlam Ammar sharif Department of Architecture Philadelphia UniversityAmman 19392Jordan

Urban researchers have maintained a constant interest in the complexity and continuity of urban space *** have applied actor-network theory(ANT)to investigate the heterogeneity of spaces and present them through the networks of their users'***,these accounts are predominantly limited in examining the extent to which these spaces may be heterogeneous when exploring such *** paper draws on recent ANT scholarship,which employs an ethnographic research conducted in a main park in a housing project at Dahiyat Al Hussein in Amman,*** findings describe the complex and unpredictable negotiations that occur with in spaces by documenting the varieties and in terrelations among user activity networks within this common and shared urban *** research reveals the extent to which spaces,parks in this case,may be heterogeneous by unpacking their *** conclusions and in sights assert then ecessity of paying attention to design detail and creating designs that are responsive to evolving user activities.

关键词： Actor-network theory User activity networks Space heterogeneity Spatial translations Relational patterns

A relational perspective on the walking activity in urban spaces:Shaping,transformation,and interrelations

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

Frontiers of Architectural Research 2023年第3期12卷 496-508页

作者： Ahlam Ammar sharif Architectural Engineering Department Faculty of EngineeringThe Hashemite UniversityZarqa 13133Jordan

New walking studies have been concerned with the multiplicity of pedestrian *** consider walking as an activity that unfolds as part of social life,allowing people to create relationships with others,where multiple walking types can be identified depending on these *** contributions,inspired by actor-network theory(ANT),suggest understanding this activity through a networked perspective that associates human and non-human actors,with a focus on their various and dynamic relations between *** focus on stabilized networks,which emphasizes the recurrence of these relations,helps in identifying and extending themultiplicity of walking activity experience and emerging *** this potential,ANT contributions are still *** paper aims to present the ANT potential in unpacking the multiplicity of the walking *** utilizes the case of Dahiyat Al Hussain park in Jordan and applies an ANT-inspired ethnographic approach to *** uses desk research,in-depth interviews,go-along interviews,and observations to engage with participants’views and *** tracing the recurring relational patterns,the paper identifies three instances when walking practice can be considered as stabilized during network shaping,transformation,and *** stabilizations provide a nuanced perspective into the multiplicity of walking practices.

关键词： Actor-network theory Pedestrian experiences Walking activity Stabilization Multiplicity

Users as co-designers:Visual-spatial experiences at Whitworth Art Gallery

在线全文

学校读者我要写书评

暂无评论

Frontiers of Architectural Research 2020年第1期9卷 106-118页

作者： Ahlam Ammar sharif Department of Architecture Philadelphia UniversityAmmanJordan

The importance of building users in the architectural field has been increasingly acknowledged in architectural *** studies have applied actor-network theory(ANT)to highlight the ways through which users are embedded in relation to the built ***,many of these studies are limited in recognizing the diverse ways users manipulate these relations as they experience the same built environment *** study draws on a recent ANT scholarship by summarizing the ethnographic research of Whitworth Art Gallery in Manchester,United *** show that users see and react to the same built environment in different ways that are not limited to their alignment or misalignment with the *** extend to include diverse interpretations and reactions(destructing,ignoring,noticing,attending,and interacting).The different user experiences explored in this research demonstrate three main themes,namely,entanglements,continuity,and transformation,which suggest new ways of recognizing the need for increasingly adaptable and inviting designs that address different user preferences and desires.

关键词： Actor-network theory Architectural design Design process Design technology User behavior

Energy-Momentum Distribution of Gravitational Waves

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

Communications in Theoretical Physics 2008年第9期50卷 664-668页

作者： M.sharif Kanwal Nazir Department of Mathematics University of the PunjabQuaid-e-Azain CampusLahore-54590Pakistan

This paper has been addressed to the well-known problem of energy in gravitational waves. We have investigated the energy of cylindrical gravitational waves in the context of General Relativity and teleparallel theory of gravity. For this purpose, the prescriptions of Einstein, Landau-Lifshitz, Bergmann-Thomson, and Moeller are used in both the theories. It is shown that these energy-momentum complexes do not provide equivalent results in the two theories. However, these turn out to be constant for all the prescriptions except Moeller in both the theories at large distances.

关键词： energy-momentum gravitational waves

Action Mechanisms of Arbuscular Mycorrhizal Fungi in Phosphorus Uptake by Capsicum annuum L.

在线全文

学校读者我要写书评

暂无评论

Pedosphere 2011年第4期21卷 502-511页

作者： M.sharif N.CLAASSEN Department of Soil and Environmental Sciences NWFP Agricultural University Department of Crop Sciences (Plant Nutrition) Georg-August-University Gttingen

A pot experiment was conducted to investigate the action mechanisms phorus （P） uptake of Capsicum annuum L. in a sterilized fossil Oxisol of arbuscular mycorrhizal （AM） fungi in phos- Three P levels of 0, 10 and 200 mg kg-1 soil （P0, P10 and P200, respectively） without and with AM fungal inoculation were applied as Ca（H2PO4）2-H20. Shoot dry matter yields and shoot P uptake increased significantly （P 〉 0.05） by the inoculation of AM fungi at P0 and P10. Root length and P concentration in soil solution increased with the inoculation of AM fungi but the root：shoot ratio decreased or remained constant. Around 50% roots of inoculated plants were infected by AM and the external hyphae amounted to 20 m g^-1 soil at P10 and P200. The hyphae surface area of the infected root cylinder amounted to 11 and 2 cm^2 cm^-2 root at P0 and P10, respectively. The increased P uptake of inoculated plants was mainly because of an up to 5 times higher P influx of the infected root. Model calculations showed that the root alone could not have achieved the measured P influx in both infected and non-infected roots. But the P influx for hyphae calculated by the model was even much higher than the measured one. The P uptake capacity of hyphae introduced in the model was too high. Model calculations further showed that the depletion zone around roots or hyphae was very narrow. In the case of the root only 7% of the soil volume would contribute P to the plant, while in the case of hyphae it would be 100%. The results together with the model calculations showed that the increased P uptake of AM inoculated plants could be explained partly by the increased P concentration in the soil solution and by the increased P absorbing surface area coming from the external hyphae.

关键词： hyphae mechanistic model phosphorus influx root infection root morphology