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On the existence and stability of traversable wormhole solutions with novel shapefunctions in the framework of F(R,L_(m))gravity

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Communications in Theoretical Physics 2024年第5期76卷 114-127页

作者： Sourav Chaudhary Jitendra Kumar S K Maurya Sweeti Kiroriwal Abdul Aziz Department of Mathematics Central University of HaryanaJant-PaliMahendergarhIndia Department of Mathematical and Physical Sciences College of Arts and ScienceUniversity of NizwaP.O.Box 33Nizwa 616Oman

In this work,we have explored wormhole(WH)solutions in F(R,L_(m))gravity by assuming the Morris-Thorne WH metric and F(R,Lm)=R/+(1+γR)L_(m),whereγis the free model parameter.We determined the WH solutions by utilizing two newly developed shape functions(SF)that satisfy all basic conditions for a WH’s physical validity.We also observe that the null energy condition(NEC)behaves negatively.Finally,for both models,we use the volume integral quantifier(VIQ)and Tolman-Oppenheimer-Volkoff(TOV)equation to determine how much exotic matter is needed near the WH throat and the stability of the WH.The extensive detailed discussions of the matter components have been done via graphical analysis.The obtained WH geometries meet the physically acceptable conditions for a stable wormhole.

关键词： energy conditions wormhole exotic matter F(R L_(m))gravity

Thick accretion disk configurations around a compact object in the brane-world scenario

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Communications in Theoretical Physics 2023年第11期75卷 76-83页

作者： Yunzhu Wei Songbai Chen Jiliang Jing Department of Physics Key Laboratory of Low Dimensional Quantum Structures and Quantum Control of Ministry of EducationInstitute of Interdisciplinary StudiesSynergetic Innovation Center for Quantum Effects and ApplicationsHunan Normal UniversityChangshaHunan 410081China Center for Gravitation and Cosmology College of Physical Science and TechnologyYangzhou UniversityYangzhou 225009China

We have studied the equipotential surfaces of a thick accretion disk around a Casadio-Fabbri-Mazzacurati compact object in the brane-world scenario,which possesses a mass parameter together with a parameterized post-Newtonian(PPN)parameter.With the increase in the PPN parameter,the size of the thick accretion disk decreases,but the corresponding Roche lobe size increases.Thus,the larger PPN parameter yields the larger region of existing bound disk structures,where the fluid is not accreted into the central wormhole.Moreover,with the increase in the PPN parameter,the position of the Roche lobe gradually moves away from the central compact object,and the thickness of the region enclosed by the Roche lobe decreases near the compact object but increases in the region far from the compact object.Our results also show that the pressure gradient in the disk decreases with the PPN parameter.These effects of the PPN parameter on the thick accretion disk could help one to further understand compact objects in the brane-world scenario.

关键词： black hole brane world wormhole

Static spherically symmetric wormholes in f(Q,T)gravity

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Chinese Physics C 2022年第11期46卷 275-290页

作者： Moreshwar Tayde Zinnat Hassan P.K.Sahoo Sashideep Gutti Department of Mathematics Birla Institute of Technology and Science-PilaniHyderabad CampusHyderabad-500078India Department of Physics Birla Institute of Technology and Science-PilaniHyderabad CampusHyderabad-500078India

In this study,we obtain wormhole solutions in the recently proposed extension of symmetric teleparallel gravity,known as f(Q,T)gravity.Here,the gravitational Lagrangian L is defined by an arbitrary function f of Q and T,where Q is a non-metricity scalar,and T is the trace of the energy-momentum tensor.In this study,we obtain field equations for a static spherically symmetric wormhole metric in the context of general f(Q,T)gravity.We study the wormhole solutions using(ⅰ)a linear equation of state and(ⅱ)an anisotropy relation.We adopt two different forms of f(Q,T),(a)linear f(Q,T)=αQ+βT and(b)non-linear f(Q,T)=Q+λQ^(2)+ηT,to investigate these solutions.We investigate various energy conditions to search for preservation and violation among the obtained solutions and find that the null energy condition is violated in both cases of our assumed forms of f(Q,T).Finally,we perform a stability analysis using the Tolman-Oppenheimer-Volkov equation.

关键词： wormhole EoS energy conditions stability analysis f(Q,T)gravity

Non-exotic static spherically symmetric thin-shell wormhole solution in f(Q,T)gravity

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Chinese Physics C 2023年第7期47卷 173-189页

作者： Moreshwar Tayde Sayantan Ghosh P.K.Sahoo Department of Mathematics Birla Institute of Technology and Science-PilaniHyderabad CampusHyderabad-500078India

In this study,we conduct an analysis of traversable wormhole solutions within the framework of linear f(Q,T)=αQ+βT gravity,ensuring that all energy conditions hold for the entire spacetime.The solutions presented in this paper are derived through a comprehensive analytical examination of the parameter space associated with the wormhole model.This involves considering the exponents governing the redshift and shape functions,as well as the radius of the wormhole throat(r_(0)),the redshift function value at the throat(∅_(0)),and the model parameters(αandβ).Moreover,we establish bounds on these free parameters,which guarantee the satisfaction of the energy conditions throughout spacetime and also provide two solutions.Furthermore,we use the Israel junction condition to observe the stability of a thin-shell around the wormhole.Finally,we calculate the null energy condition criteria as well as the potential for the thin-shell and how it varies with the chosen shape function.

关键词： wormhole energy conditions f(Q,T)gravity junction condition thin-shell

Energy Optimised Security against wormhole Attack in IoT-Based Wireless Sensor Networks

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Computers, Materials & Continua 2021年第8期68卷 1967-1981页

作者： Hafsa Shahid Humaira Ashraf Hafsa Javed Mamoona Humayun Nz Jhanjhi Mohammed A.AlZain Department of Computer Science and Software Engineering International Islamic University IslamabadIslamabadPakistan Department of Information Systems College of Computer and Information ScienceJouf UniversityAl-JoufSaudi Arabia School of Computer Science and Engineering(SCE) Taylor’s UniversitySelangorMalaysia Department of Information Technology College of Computers and Information TechnologyTaif UniversityTaif21944Saudi Arabia

An IoT-based wireless sensor network(WSN)comprises many small sensors to collect the data and share it with the central repositories.These sensors are battery-driven and resource-restrained devices that consume most of the energy in sensing or collecting the data and transmitting it.During data sharing,security is an important concern in such networks as they are prone to many threats,of which the deadliest is the wormhole attack.These attacks are launched without acquiring the vital information of the network and they highly compromise the communication,security,and performance of the network.In the IoT-based network environment,its mitigation becomes more challenging because of the low resource availability in the sensing devices.We have performed an extensive literature study of the existing techniques against the wormhole attack and categorised them according to their methodology.The analysis of literature has motivated our research.In this paper,we developed the ESWI technique for detecting the wormhole attack while improving the performance and security.This algorithm has been designed to be simple and less complicated to avoid the overheads and the drainage of energy in its operation.The simulation results of our technique show competitive results for the detection rate and packet delivery ratio.It also gives an increased throughput,a decreased end-to-end delay,and a much-reduced consumption of energy.

关键词： IoT Internet of Things energy wormhole WSN wireless sensor networks

Two Types of Universe and wormhole From the Wave Function of Universe

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Science China Mathematics 1993年第6期36卷 738-743页

作者：沈有根丁浩刚 Shanghai Observatory Academia Sinica Shanghai 200030 PRC Deportment of Physics Peking University Beijing 100871 PRC

From the wave function of universe with a conformal scalar field obtained in this paper, it is found that there are two different types of universe: （ⅰ） baby universe （B） appearing in the region of α∈[0, H2-1～0.1lp]where lp is Plauck length; （ⅱ） parent universe （P） appearing in the region of α>H1-1～H-1where H-1 is Hubble redius. The two universes are connected with each other through quantum tunnelling effect, and transit from one to the other.The wave function of universe in this model draws a rational picture about wormhole, i.e. it induces the interaction between parent and baby universes and leads to the change of spatial topology.

关键词： wave function of universe baby universe parent universe wormhole conformal sealar field

Conventional diverting techniques and novel fibr-assisted selfdiverting system in carbonate reservoir acidizing with successful case studies

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Petroleum Research 2021年第3期6卷 247-256页

作者： Reza Abdollahi Hamid Esfandyari Mahdi Nadri Pari Afshin Davarpanah EOR Research Department Research Institute of Petroleum IndustryTehranIran Department of Petroleum Engineering Abadan Faculty of Petroleum EngineeringPetroleum University of Technology(PUT)AbadanIran Department of Mathematics Aberystwyth UniversityAberystwyth SY233BZUnited Kingdom

Conventional diverting techniques may not be useful,and the use of the advanced and well-documented diverting technique is needed to overcome the complexity and heterogeneity of carbonate reservoirs.Nowadays,there have been a lot of materials and techniques utilized for acid diversion.This paper aimed to consider various utilization of fiber-assisted self as the diverting system in acidifying carbonate reservoirs.One of the main reasons for its ability to overcome uncertainty is that the fiber itself is an inherent property,allowing for an automatic diversion adjustment downhole.When a media with infinite permeability,such as a perforation tunnel or natural fracture,is filled and bridged with a material of finite permeability such as degradable fiber,this creates a temporary skin to injectivity in that zone.This is a powerful concept,as it is a way,despite uncertainty from a lack of logging data or uncertainty in the data itself,of dampening the reservoir’s natural permeability contrast.It does not rely on petrophysical certainty to design a successful treatment.

关键词： Acidizing Carbonate reservoirs Diversion techniques Fiber-assisted self-diverting system Fracture wormhole

Estimation of pore volumes to breakthrough number in limestone cores by derivation of an empirical model

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Petroleum Research 2021年第3期6卷 264-270页

作者： Sina Lohrasb Radzuan Junin Department of Petroleum Engineering School of Chemical and Energy EngineeringFaculty of EngineeringUniversiti Teknologi MalaysiaUTM81310Johor BahruMalaysia Institute for Oil and Gas Universiti Teknologi Malaysia81310Johor BahruMalaysia

Acidizing in carbonate formations is an inevitable stimulation treatment method for oil and gas wells.In the limestone,acidizing stimulation makes capillary wormholes to increase fluids flow reservoir production.The pore volume to breakthrough number is one of the main indexes for recognizing the wormhole structure.Therefore,finding the pore volume to breakthrough number is one of the main goals in the limestone acidizing.Obtaining this number is always required for experimental works,which needs time,energy and cost.The purpose of this research is to develop an empirical method to estimate an acceptable result for this number merely by implementing limestone core and acid properties without any experimental work.In order to create a wormhole,an empirical method is developed using the law of conservation of mass considering that the core of limestone as an isolated package and the overall mass is constant in this package in the acidizing period.Also,to develop the mathematical section,the Damk€ohler number is used.Since this number must be calculated experimentally,a constant number is created in the model to eliminate the Damkohler number.An average accuracy of 92.31%is obtained for the developed empirical model by comparing the results obtained from the other three experimental and numerical works.This study conclusively provides a thoroughly empirical method for estimating a high accuracy of the pore volume to breakthrough number by only using known physical properties limestone core and acid.

关键词： Acidizing Pore volumes to breakthrough Limestone wormhole Empirical model

wormholes propagation for fractured-vuggy formation:Laboratory tests,numerical simulation and field application

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Petroleum 2017年第4期3卷 438-446页

作者： Fei Liu Yu Sang Nanxing Xie Li Li Li Ran Weihua Chen Engineering Technology Research Institute Southwest Oil&Gas Field CompanyPetroChinaChengdu610017China Research and Development Center of the National Energy High Sulfur Gas Reservoir Southwest Oil&Gas Field CompanyPetroChinaChengdu610017China

The propagation of wormhole is vital important for matrix acidizing and acid fracturing in carbonate reservoirs.While the formation of acid dissolved wormhole is derived from heterogeneous physical and chemical transportations and reactions.Alveolate dissolved pores,krast caves,and natural fissures are the major reservoir spaces for the Sinian dolomite formation in the Anyue gas field of the Sichuan Basin.There were four categories of formation,which are matrix dominated,inter-breccia dissolved pore dominated,dissolved pore and cave dominated,and fissure and cave dominated,based on the development intensity and connectedness of caves and fissures.The caves and fissures make the wormhole formation and propagation particularly complicated.Firstly,the 3-D topological structure of dissolved pores,vugs,fissures and throats inside cores is quantitatively scanned by CT imaging technology for its feature of vivid and damage-free.Secondly,3-D patterns of wormhole are obtained with CT scanning after core flooding by acid.Additionally,the porethroat network model is reconstructed with digital cores technology.Then,the size and ratio of pore and throat before and after core flooding by acid is analyzed and the absolute permeability of pore scale flow is numerically simulated to understand the fundamental influence of pores and vugs distribution and connectedness on wormhole propagation.Lastly,the wormhole pattern gained by CT scanning and simulating with two-scale model is compared.Meanwhile,the corrected two-scale model is utilized to simulate the wormhole propagation for matrix acidizing and acid fracturing of Sinian fractured-vuggy dolomite in Anyue gas field,Sichuan Basin.The optimized injection rate and volume were in agreement with the characteristic matrix acidizing operating curve,which indicates that the two-scale model was suitable for matrix acidizing optimization design of such formations.In addition,the simulated acid etched fracture length with considering the dynamic wormhole leakoff was consistent with the we

关键词： CT scanning Digital core Dolomite wormhole Fractured-vuggy reservoir Matrix acidizing Acid fracturing