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Control of rock joint parameters on deformation of tunnel opening

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Journal of Rock Mechanics and Geotechnical Engineering 2016年第4期8卷 489-498页

作者： Suman panthee p.K.singh Ashutosh Kainthola T.N.singh Central Department of Geology Tribhuvan University Department of Earth Sciences Indian Institute of Technology Bombay

In this paper, stress behavior of shallow tunnels under simultaneous non-uniform surface traction and symmetric gravity loading was studied using a direct boundary element method（BEM）. The existing fullplane elastostatic fundamental solutions to displacement and stress fields were used and implemented in a developed algorithm. The cross-section of the tunnel was considered in circular, square, and horseshoe shapes and the lateral coefficient of the domain was assumed as unit quantity. Double-node procedure of the BEM was applied at the corners to improve the model including sudden traction changes. The results showed that the method used was a powerful tool for modeling underground openings under various external as well as internal loads. Eccentric loads significantly influenced the stress pattern of the surrounding tunnel. The achievements can be practically used in completing and modifying regulations for stability investigation of shallow tunnels.

关键词： Stress behavior Boundary element method(BEM) Shallow tunnels Eccentricity

Insight into the liver dysfunction in COVID-19 patients: Molecular mechanisms and possible therapeutic strategies

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World Journal of Gastroenterology 2023年第14期29卷 2064-2077页

作者： Naina Khullar Jasvinder singh Bhatti Satwinder singh Bhawana Thukral p Hemachandra Reddy Gurjit Kaur Bhatti Department of Zoology Mata Gujri CollegeFatehgarh Sahib 140407PunjabIndia Laboratory of Translational Medicine and Nanotherapeutics Department of Human Genetics and Molecular MedicineSchool of Health SciencesCentral University of PunjabBathinda 151401PunjabIndia Department of Computer Science and Technology Central University of PunjabBathinda 151401PunjabIndia Department of Nutrition and Dietetics University Institute of Applied Health SciencesChandigarh UniversityMohali 140413PunjabIndia Department of Internal Medicine Texas Tech University Health Sciences CenterLubbockTX 79430United States Department of Medical Lab Technology University Institute of Applied Health SciencesChandigarh UniversityMohali 140413PunjabIndia

As of June 2022,more than 530 million people worldwide have become ill with coronavirus disease 2019(COVID-19).Although COVID-19 is most commonly associated with respiratory distress(severe acute respiratory syndrome),metaanalysis have indicated that liver dysfunction also occurs in patients with severe *** studies revealed distinctive patterning in the receptors on the hepatic cells that helps in viral invasion through the expression of angiotensinconverting enzyme *** has also been reported that in some patients with COVID-19,therapeutic strategies,including repurposed drugs(mitifovir,lopinavir/ritonavir,tocilizumab,etc.)triggered liver injury and cholestatic *** proven indicators support cytokine storm-induced hepatic *** there are 1.5 billion patients with chronic liver disease worldwide,it becomes imperative to critically evaluate the molecular mechanisms concerning hepatotropism of COVID-19 and identify new potential *** review also designated a comprehensive outlook of comorbidities and the impact of lifestyle and genetics in managing patients with COVID-19.

关键词： COVID-19 Liver damage pharmacotherapy Cytokine storm Molecular mechanisms

FORECASTING OF A NONLINEAR CASCADE FOR WATERSHED RUNOFF

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Chinese Journal of Oceanology and Limnology 1989年第2期7卷 169-177页

作者：陈绳甲 Vijay p.singh Wuhan Institute of Hydraulic and Electric power Engineering Louisiana State University U.S.A

Forecasting of a nonlinear cascade was developed for modeling watershed runoff, and was tested by computing the direct runoff hydrograph for two rainfall- runoff events on a small watershed in China . The forecasting model was superior to Ding s variable unit hydrograph method and the method of limited differences for these two events.

关键词： runoff watershed rainfall reservoirs forecasting cascade hydrologic analogy flood outflow

Dynamics of one-prey two-predator system with square root functional response and time lag

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International Journal of Biomathematics 2015年第3期8卷 23-44页

作者： O. p. Misra poonam Sinha Chhatrapal singh School of Mathematics and Allied SciencesJiwaji University Gwalior (M.P.)-474011 India Department of MathematicsS. M. S. Govt. Model Science College Gwalior (M.p.)-474010 India

Animals grouping together is one of the most interesting phenomena in population dynamics and different functional responses as a result of prey-predator forming groups have been considered by many authors in their models. In the present paper we have considered a model for one prey and two competing predator populations with time lag and square root functional response on account of herd formation by prey. It is shown that due to the inclusion of another competing predator, the underlying system without delay becomes more stable and limit cycles do not occur naturally. However, after considering the effect of time lag in the basic system, limit cycles appear in the case of all equilibrium points when delay time crosses some critical value. From the numerical simulation, it is observed that the length of delay is minimum when only prey population survives and it is maximum when all the populations coexist.

关键词： Stability square root functional response Hopf bifurcation time delay.

Modeling and analysis of the transmission dynamics of mosquito-borne disease with environmental temperature fluctuation

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International Journal of Modeling, Simulation, and Scientific Computing 2022年第3期13卷 31-73页

作者： O.p.Misra Joydip Dhar Omprakash singh Sisodiya School of Mathematics and Allied Sciences Jiwaji University Gwalior 474011M.P.India Department of Applied Sciences ABV-Indian Institute of Information Technology and Management Gwalior 474015 M.P.India

Most of the vector-borne diseases show a clear dependence on seasonal variation,including climate *** this paper,we proposed a nonautonomous mathematical model consisting of a periodic system of nonlinear differential *** the proposed model,the realistic functional forms for the different temperature-dependent parameters are *** autonomous system of the proposed model is also *** nontrivial solution of the autonomous model is locally asymptotically stable if R0point of the autonomous model exists when R0>1 and proved that endemic solution is linearly stable when R0>*** nonautonomous model is shown to have a nontrivial disease-free periodic state,which is globally asymptotically stable whenever temperature-dependent reproduction number is less than *** is observed that a unique positive endemic periodic solution of the nonautonomous system exists only when a temperature-dependent reproduction number greater than unity,which makes for the persistence of the *** simulation has been carried out to support the analytical results and shows the effects of temperature variability in the life span of mosquitoes as well as the persistence of the disease.

关键词： Mosquito-borne disease seasonality temperature-dependent reproduction number periodic steady states

Comparative study of 2mol% Li- and Mn-substituted lead-free potassium sodium niobate ceramics

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International Journal of Minerals,Metallurgy and Materials 2014年第12期21卷 1241-1246页

作者： Asha Dahiya O.p.Thakur J.K.Juneja Sangeeta singh Dipti School of Applied Sciences Netaji Subhas Institute of Technology Dwarka University of Delhi Department of physics Hindu College Department of physics Geeta Vidya Mandir Girls College School of physics & Material Sciences Thapar University

The effect of Li and Mn substitution on the dielectric, ferroelectric and piezoelectric properties of lead free K0.5Na0.5NbO3 （KNN） was investigated. Samples were prepared using a conventional solid state reaction method. The sintefing temperature for all the samples was 1050℃. The optimum doping concentration for the enhancement of different properties without the introduction of any other co-dopants such as Ti, Sb, and La was investigated. X-ray diffraction analysis confirmed that all the samples crystallize in a single phase perovskite structure. The dielectric properties were investigated as a function of temperature and applied electric field frequency. Compared with Li-substituted KNN （KLNN）, Mn-substituted KNN （KMNN） exhibited a higher dielectric constant εmax （i.e., 4840） at its critical transition temperature Tc （i.e., 421℃） along with a lower value of tangent loss at 10 kHz and greater values of saturation polarisation ps （i.e., 20.14 μC/cm^2） and remnant polarisation pr （i.e., 15.48 μC/cm^2）. The piezoelectric constant （d33） of KMNN was 178 pC/N, which is comparable to that of lead-based hard ceramics. The results presented herein suggest that B-site or Mn substitution at the optimum concentration results in good enhancement of different properties required for materials used in memory devices and other applications.

关键词： ceramics dielectric properties ferroelectricity piezoelectricity substitution comparative study

Bianchi Type-Ⅲ Cosmological Models with Gravitational Constant G and the Cosmological Constant A

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Chinese physics Letters 2007年第12期24卷 3325-3327页

作者： J. p. singh R. K. Tiwari pratibha Shukla Department of Mathematical Sciences A.P.S. University Rewa (MP) India Department of Mathematics Govt. Model Science College Rewa (MP) India

Einstein field equations with variable gravitational and cosmological constants are considered in the presence of perfect fluid for the Bianchi type-Ⅲ universe by assuming conservation law for the energy-momentum tensor. Exact solutions of the field equations are obtained by using the scalar of expansion proportional to the shear scalar θ∝σ, which leads to a relation between metric potential B = Cn, where n is a constant. The corresponding physical interpretation of the cosmological solutions are also discussed.

关键词： Cosmological Models Cosmological Constant

Flexural fatigue strength of steel fibrous concrete containing mixed steel fibres

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Journal of Zhejiang University-Science A(Applied physics & Engineering) 2006年第8期7卷 1329-1335页

作者： singh S.p. MOHAMMADI Y. MADAN S.K. Civil Engineering National Institute of Technology Jalandhar 144 011 India Civil Engineering University of Mohaghegh Ardebili Ardebil 179 Iran Civil Engineering National Institute of Technology Kurukushetra 136 119 India

This paper reports investigation conducted to study the fatigue performance of steel fibre reinforced concrete (SFRC) containing fibres of mixed aspect ratio. An extensive experimental program was conducted in which 90 flexural fatigue tests were carried out at different stress levels on size 500 mm×100 mm×100 mm SFRC specimens respectively containing 1.0%, 1.5% and 2.0% volume fraction of fibres. About 36 static flexural tests were also conducted to determine the static flexural strength prior to fatigue testing. Each volume fraction of fibres incorporated corrugated mixed steel fibres of size 0.6 mm×2.0 mm×25 mm and 0.6 mm×2.0 mm×50 mm in ratio 50:50 by weight. The results are presented both as S-N relationships, with the maximum fatigue stress expressed as a percentage of the strength under static loading, and as relationships between actually applied fatigue stress and number of loading cycles to failure. Two-million-cycle fatigue strengths of SFRC containing different volume fractions of mixed fibres were obtained and compared with plain concrete.

关键词： Fatigue strength Static flexural strength Stress level Stress ratio Steel fibre reinforced concrete (SFRC)

Effects of mechanical vibration on the physical,metallurgical and mechanical properties of cast A308(LM21)aluminum alloy

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International Journal of Minerals,Metallurgy and Materials 2022年第6期29卷 1206-1215页

作者： Siddharth Yadav S.p.Tewari J.K.singh S.C.Ram Department of Mechanical Engineering Indian Institute of Technology(BHU)Varanasi 221005India Department of Metallurgical Engineering Indian Institute of Technology(BHU)Varanasi 221005India

This study investigated the microstructure,physical,and mechanical properties of die-cast A308 alloy subjected to mechanical vibration during *** frequencies(0,20,30,40,and 50 Hz)at constant amplitude(31μm)were employed using a power amplifier as the power input device.X-ray diffraction,optical microscopy,and scanning electron microscopy were used to examine the morphological changes in the cast samples under stationary and vibratory *** features of the castings were evaluated using Image J *** average values of metallurgical features,including primaryα-Al grain size,dendrite arm spacing,average area of eutectic silicon,aspect ratio,and percentage porosity,reduced by 34%,59%,56%,22%,and 62%,respectively,at 30 Hz frequency compared with stationary *** tests of the cast samples showed that the yield strength(YS),ultimate tensile strength(UTS),percentage elongation(%EL),and microhardness(HV)increased by 8%,13%,17%,and 16%,respectively,at 30 Hz frequency compared with stationary *** fractured surface of the tensile specimens exhibited mixed-mode fracture behavior because of brittle facets,cleavage facets,ductile tearing,and dimple *** presence of small dimples showed that plastic deformation occurred before fracture.

关键词： mechanical vibration microstructures microhardness tensile strength fractography