#### Journal of Applied Mathematics and Physics

Journal Information

ISSN / EISSN :
23274352 / 23274379

Current Publisher: Scientific Research Publishing, Inc. (10.4236)

Total articles ≅ 1,410

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SHERPA/ROMEO

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#### Latest articles in this journal

Published: 19 January 2020

Journal of Applied Mathematics and Physics, Volume 8, pp 218-228; doi:10.4236/jamp.2020.82017

**Abstract:**

In order to improve the electrical and frequency characteristics of SiGe heterojunction bipolar transistors (HBTs), a novel structure of SOI SiGe heterojunction bipolar transistor is designed in this work. Compared with traditional SOI SiGe HBT, the proposed device structure has smaller window widths of emitter and collector areas. Under the act of additional uniaxial stress induced by Si0.85Ge0.15, all the collector region, base region and emitter region are strained, which is beneficial to improve the performance of SiGe HBTs. Employing the SILVACOⓇ TCAD tools, the numerical simulation results show that the maximum current gain βmax, the Earley voltage VA are achieved for 1062 and 186 V, respectively, the product of β and VA, i.e., β ×VA, is 1.975 × 105 V and, the peak cutoff frequency fT is 419 GHz when the Ge component in the base has configured to be a trapezoidal distribution. The proposed SOI SiGe HBT architecture has a 52.9% improvement in cutoff frequency fT compared to the conventional SOI SiGe HBTs.

Published: 19 January 2020

Journal of Applied Mathematics and Physics, Volume 8, pp 307-314; doi:10.4236/jamp.2020.82025

**Abstract:**

In this paper, we considered with the following Schrödinger-Kirchhoff type problem: -(a+b ʃRN|∇u|2dx)∇u + V(x)u = f(x,u) in RN. We put forward general assumptions on the nonlinearity f with the subcritical growth and we find a ground state solution being a minimizer of the energy functional associated with a Nehari-Pankov manifold by using a linking theorem.

Published: 19 January 2020

Journal of Applied Mathematics and Physics, Volume 8, pp 349-366; doi:10.4236/jamp.2020.82027

**Abstract:**

Character of contract pressure distribution between the outside surface of the sealing material and rigid cylinder wall depending on geometrical sizes and mechanical properties of a sealer under its unilateral compression, is defined. The magnitude of the axial load for achieving tightness is determined. The dependence between the magnitude of the axial load necessary for achieving tightness and geometrical sizes is determined. It is shown that with a decrease in the height of the sealing element, the axial load necessary for achieving tightness greatly increases. Threshold height of the sealer, above which contact pressure depends little on the magnitude of the axial load, is defined. The stress-strain state of the sealing element is defined with regard to viscous-elastic properties of its material. It is shown that this greatly influences its sealing ability.

Published: 1 January 2020

Journal of Applied Mathematics and Physics, Volume 8, pp 1180-1192; doi:10.4236/jamp.2020.86089

**Abstract:**

Investigating local dynamics of equilibrium points of nonlinear systems plays an important role in studying the behavior of dynamical systems. There are many different definitions for stable and unstable solutions in the literature. The main goal to develop stability definitions is exploring the responses or output of a system to perturbation as time approaches infinity. Due to the wide range of application of local dynamical system theory in physics, biology, economics and social science, it still attracts many researchers to play with its definitions to find out the answers for their questions. In this paper, we start with a brief review over continuous time dynamical systems modeling and then we bring useful examples to the playground. We study the local dynamics of some interesting systems and we show the local stable behavior of the system around its critical points. Moreover, we look at local dynamical behavior of famous dynamical systems, Hénon-Heiles system, Duffing oscillator and Van der Pol equation and analyze them. Finally, we discuss about the chaotic behavior of Hamiltonian systems using two different and new examples.

Published: 1 January 2020

Journal of Applied Mathematics and Physics, Volume 8, pp 1168-1179; doi:10.4236/jamp.2020.86088

**Abstract:**

A path π = [v1, v2, …, vk] in a graph G = (V, E) is an uphill path if deg(vi) ≤ deg(vi+1) for every 1 ≤ i ≤ k. A subset S ⊆ V(G) is an uphill dominating set if every vertex vi ∈V(G) lies on an uphill path originating from some vertex in S. The uphill domination number of G is denoted by γup(G) and is the minimum cardinality of the uphill dominating set of G. In this paper, we introduce the uphill domination polynomial of a graph G. The uphill domination polynomial of a graph G of n vertices is the polynomial , where up(G, i) is the number of uphill dominating sets of size i in G, and γup (G) is the uphill domination number of G, we compute the uphill domination polynomial and its roots for some families of standard graphs. Also, UP (G, x) for some graph operations is obtained.

Published: 1 January 2020

Journal of Applied Mathematics and Physics, Volume 8, pp 1135-1154; doi:10.4236/jamp.2020.86086

**Abstract:**

In this paper, a new complex variable defined as “precursive time” able to correlate general relativity (GR) and quantum field theory (QFT) in a single principle was characterized. The thesis was elaborated according to a hypothesis coherent with the “Einstein’s General Theory of Relativity”, making use of a new mathematical-topological variety called “time-space” developed on the properties of the hypersphere and explained mathematically through the quaternion of Hurwitz-Lipschitz algebra. In this publication we pay attention to the interaction between the weak nuclear force theory (EWT) and the nuclear mass of the Standard Model.

Published: 1 January 2020

Journal of Applied Mathematics and Physics, Volume 8, pp 1155-1167; doi:10.4236/jamp.2020.86087

**Abstract:**

In this paper we discuss the uniqueness and existence of solution to a real gas flow network by employing graph theory. A directed graph is an efficient way to represent a gas network. We consider steady state real gas flow network that includes pipelines, compressors, and the connectors. The pipelines and compressors are represented as edges of the graph and the interconnecting points are represented as nodes of the graph representing the network. We show that a unique solution of such a system exists. We use monotonicity property of a mapping to proof uniqueness, and the contraction mapping theorem is used to prove existence.

Published: 1 January 2020

Journal of Applied Mathematics and Physics, Volume 8, pp 1374-1401; doi:10.4236/jamp.2020.87105

**Abstract:**

The Fourier equation explains the dynamics of heat transfer. But bringing this phenomenon closer to the notion of fibration seems difficult to achieve. This study then aims to find the solution of the one-dimensional Fourier equation and to interpret it in terms of bundle. And then apply the results obtained at the Kankule site in Katana in South Kivu. To do this work, we resorted to geometric or topological analysis of the Hopf fibration of the unit sphere S3 (identifiable in SU(2)). We had taken the temperatures of the thermal waters and the soil of Kankule, from 2010 to 2014, in situ. And laboratory analyses had allowed us to know the physical and chemical properties of the soil and water at each of our 14 study sites in Kankule. The data of the geomagnetic field of each site, were taken in on the site NOAA, for our period of study. We then determined the integral curve (geotherm) of the Fourier equation and wrote it as a unit quaternion which is a bundle. The constants intervened in the geotherm, for each site of Kankule, we had obtained them statistically. We have found that the geotherm of each Kankule site is a bundle. We have compared this model to the bundle model of the geomagnetic field. From there we realized that to determine the energy potential of Kankule, we should consider the thermal springs separately. We were able to find a connection between the fibration of the geomagnetic field and the heat field for the Kankule site.

Published: 1 January 2020

Journal of Applied Mathematics and Physics, Volume 8, pp 1362-1373; doi:10.4236/jamp.2020.87104

**Abstract:**

Linear algebra has a very important application in physics and technical disciplines. This article conducted a questionnaire survey on the factors that affect the effect of linear algebra learning; the questionnaire contains several aspects of learning attitude, learning interest, learning methods, teaching methods, etc.; based on recycling data, cross chi-square test and multiple logistic regression analysis are used to obtain the factors that affect the effect of linear algebra learning. The research results show that: learning methods, learning attitudes, teaching methods and elementary algebra basics are the main factors that affect the learning effect of linear algebra; among them, there are positive correlations between teaching methods, learning methods, learning attitudes and learning effects; teaching methods, learning methods 3. The three principal components of learning attitude are positively correlated. Based on the research and analysis, the following conclusions are drawn: finding a suitable learning method for the college students and maintaining a positive learning attitude are effective means to improve the linear algebra learning effect of the college students; in teaching, it is recommended to advance with the times, the teaching content and teaching methods innovate to stimulate students’ interest in learning, thus improving the learning effect of college students’ linear algebra courses.

Published: 1 January 2020

Journal of Applied Mathematics and Physics, Volume 8, pp 1346-1361; doi:10.4236/jamp.2020.87103

**Abstract:**

STMV beamforming algorithm needs inversion operation of matrix, and its engineering application is limited due to its huge computational cost. This paper proposed block iterative STMV algorithm based on one-phase regressive filter, matrix inversion lemma and inversion of block matrix. The computational cost is reduced approximately as 1/4 M times as original algorithm when array number is M. The simulation results show that this algorithm maintains high azimuth resolution and good performance of detecting multi-targets. Within 1 - 2 dB directional index and higher azimuth discrimination of block iterative STMV algorithm are achieved than STMV algorithm for sea trial data processing. And its good robustness lays the foundation of its engineering application.