bluuebunny/crossref_metadata_2025 huggingface dataset:
Charged AdS black holes with finite electrodynamics in 4D Einstein-Gauss-Bonnet gravity
Authors: Jusufi Kimet
Published: December 2022

Using a modified expression for the electric potential in the context of T-duality [Gaete and Nicolini, Phys. Lett. B, 2022], we obtained an exact charged solution within the 4D Einstein-Gauss-Bonnet (4D EGB) theory of gravity in the presence of a cosmological constant. We show that the solution also exists in the regularized 4D EGB theory. Moreover, we point out a correspondence between the black hole solution in the 4D EGB theory and the solution in the non-relativistic Horava–Lifshitz theory. The black hole solution is regular and free from singularity. As a special case, we derive a class of well known solutions in the literature.
A robust HD-sEMG sensor suitable for convenient acquisition of muscle activity in clinical post-stroke dysphagia
Authors: Zhao Nan , Zhao Bolun , Shen Gencai , Jiang Chunpeng , Wang Zhuangzhuang , Lin Zude , Zhou Lanshu , Liu Jingquan
Published: December 2022

Objective. A flexible high-density surface electromyography (HD-sEMG) sensor combined with an adaptive algorithm was used to collect and analyze the swallowing activities of patients with Post-stroke dysphagia. Approach. The electrode frame, modified electrode, and bonded substrate of the sensor were fabricated using a flexible printed circuit process, controlled drop coating, and molding, respectively. The adaptation algorithm was achieved by using Laplace and Teager-Kaiser energy operators to extract active segments, a cross-correlation coefficient matrix (CCCM) to evaluate synergy, and multi-frame real-time dynamic root mean square (RMS) to visualize spatiotemporal information to screen lesions and level of dysphagia. Finally, support vector machines (SVM) were adopted to explore the classification accuracy of sex, age, and lesion location with small sample sizes. Main results. The sensor not only has a basic low contact impedance (0.262 kΩ) and high signal-to-noise ratio (37.284 ± 1.088 dB) but also achieves other characteristics suitable for clinical applications, such as flexibility (747.67 kPa) and durability (1000 times) balance, simple operation (including initial, repeated, and replacement use), and low cost ($ 15.2). The three conclusions are as follows. CCCM can be used as a criterion for judging the unbalanced muscle region of the patient’s neck and can accurately locate unbalanced muscles. The RMS cloud map provides the time consumption, swallowing times, and unbalanced areas. When the lesion location involves the left and right hemispheres simultaneously, it can be used as an evidence of relatively severely unbalanced areas. The classification accuracy of SVM in terms of sex, age, and lesion location was as high as 100%. Significance. The HD-sEMG sensor in this study and the adaptation algorithm will contribute to the establishment of a larger-scale database in the future to establish more detailed and accurate quantitative standards, which will be the basis for developing more optimized screening mechanisms and rehabilitation assessment methods.
Study on Vibrational Properties of Vehicle and Track System Caused by Deformation of Tunnel Base
Authors: Pengmao Ren-Qian , Li Bin
Published: December 2022

In this paper, the vehicle track tunnel coupling dynamic model is established by using finite element software, and the model is verified. Based on this, the vibration characteristics of the vehicle and track system caused by the settlement of the tunnel foundation are studied. The calculation results show that: (1) the short wave in the tunnel settlement wavelength has a great influence on the dynamic characteristics of vehicles and track structures, and the vibration characteristics of vehicle track system decrease with the increase of wavelength, so it is suggested to control the wavelength above 25 m. (2) The dynamic index of the vehicle and track increases significantly with the increase of amplitude, which affects the driving stability and track operation. Through calculation, it is recommended to control the amplitude below 20 mm. (3) The influence of tunnel base settlement on driving is related to speed. The greater the train speed is, the greater the influence on driving will be. So the train speed should be controlled. (4) Higher running speed will endanger the safety of train operation and the stability of the track structure, so the train running speed should be lower than 200 km/h. The above research provides some theoretical guidance for track maintenance and operation.
Numerical Simulation on Field Characteristics of the Horizontal Gas Jet Flow of Underwater Vehicle
Authors: Du Jun-min , Li Guang-hua , Fu Ben-Shuai , You Chuang
Published: December 2022

Solid rocket motors are important for the propulsion of underwater vehicles, especially for rapid maneuvering. To study the characteristics of the gas jet flow field generated by the engine of the underwater vehicle, a numerical calculation model considering gravity and phase transition was established. The basic laws of formation and evolution of jet bubbles were studied, and the unsteady characteristics of the jet flow field considering phase transition and the influence of inflow velocity and attack angle on the jet were analyzed. The results show the gas bubbles successively take on “concave” and “convex” shapes, and there exist “rebound” and “nesting” phenomena after the gas is accelerated and injected into water by the nozzle; the engine considering the phase transition process can obtain larger momentum and the degree of pressure fluctuation becomes smaller, which contributes to improving the propulsion efficiency of solid rocket motors by adding the gas-liquid phase transition model; the inlet flow has an inhibitory effect on the pressure pulsations of the flow field, and the influence of the wake on the vehicle which adopts rocket assist decreases as the speed increases; the upward deflection of the gas bubbles intensifies and the rupture of gas bubbles become closer to the nozzle outlet as the attack angle increases.
Numerical Simulation of Close-Range Interference of Main Engine Jet/Rudder
Authors: Li Kangkang , Liu Yuwei
Published: December 2022

Carrier rockets and certain spaces are usually driven by the tail engine. Some spaces can increase the flap at the end of the aircraft as the control plane. When the main jet engine opens, the jet flow disturbs the body flap seriously. The engine exhausts are usually mixed gas, but it is difficult to numerically simulate multi-component gas directly. Generally, the similarity criterion is adopted to convert hot jet gas medium into cold jet air medium for calculation. In this paper, the numerical simulation of close interference between the main engine jet and the flap is carried out for a simplified aircraft model, and the flow field of jet interference under different incoming Mach numbers is analyzed. The result shows that a similar parameter mass flow ratio can improve the accuracy of numerical simulation.
Experiments of Gas-water Cooperative Flooding in Fracture Network System
Authors: Guo Wanjiang , Li Aifen , An Guoqiang
Published: December 2022

Fractures are the main seepage channels and the critical oil storage space in fracture-vuggy reservoirs. In this paper, the staggered fracture system was abstracted into an orthogonal fracture network. A physical experimental model was made with a laser-etched acrylic plate. The physical experiments of water flooding, gas flooding, water-alternating-gas, and simultaneous-water-and-gas were carried out using the physical experiment model of the fracture network. The results show that gas is more accessible to break through in gas flooding than water in water flooding, resulting in a lower recovery factor. Water-alternating-gas and simultaneous-water-and-gas can effectively improve oil displacement efficiency through the action of gravity difference and the interaction mechanism of gas and water. Increasing the injection rate properly, increasing slug size properly before water and gas breakthrough during water-alternating-gas simultaneous-water-and-gas, and decreasing the gas-water ratio properly during simultaneous-water-and-gas simultaneous-water-and-gas can effectively expand the sweep scope and improve recovery. The experiment provides a basis for efficient water and gas injection development in fracture-vuggy reservoirs.
Hydrodynamic Derivative Calculation and Turning Performance Simulation of Amphibious Aircraft
Authors: Shi Sheng-zhe , Sang Teng-jiao , Liu Xiao-feng , Sun Gang
Published: December 2022

To improve the rotation efficiency of amphibious aircraft on the water surface, CFD technology is used to simulate maneuverable motion in this paper. The numerical calculations of direct navigation, oblique towing, no drift angle in rotating arm motion, drift angle in rotating arm motion, direct navigation with rudder, and planar motion are carried out, respectively. The hydrodynamic derivatives such as position derivative, rotation derivative, coupling derivative, rudder derivative, and added mass are obtained. On this basis, the rotational performance of amphibious aircraft is predicted. The results show that when the rudder is fully deflected, the rotation radius is 3159.1 m; when the engine differential and rudder run together, the rotation radius is 1216.8 m; the engine differential can effectively improve the rotation efficiency of amphibious aircraft on the water surface.
Distillability Problem of 4×4 Monomial Matrices
Authors: Wang Yijin , Zhang Ao , Zhang Hong
Published: December 2022

It is a fundamental problem in quantum information whether a particular quantum state of a composite system is entangled. It has enormous potential in quantum error correction, quantum cryptography, and quantum teleportation applications. This problem can be transferred in the form of a mathematical conjecture called the distillation conjecture. In the first section of this paper, relevant physical and mathematical information is presented, including basic linear algebra knowledge, the statement, and concrete applications of multiple mathematical knowledge like conjugate, eigenvalue, and singular value. Then, we introduce the distillation conjecture in a mathematical version for a more precise mathematical analysis. In an effort to make more significant headway in proving the conjecture, we selected some theories and findings relating to the Kronecker product, Kronecker sum, eigenvalue, and singular value, then evaluated and grouped them. In addition, we provided multiple proofs of the conjecture under varying conditions and made numerous attempts and hypotheses regarding how to establish the conjecture.
Simulation Calculation of New Steel Tube Structure based on Vortex-Induced Vibration Control Technology of Steel Tube Tower
Authors: Zhou Anqi , Zhang Xueli , Xiong Xiaoyu , Zhu Jiayi , Xia Dongsheng
Published: December 2022

This paper proposes a new three-tube structure to replace the original steel tube. The vortex-induced vibration of the three-tube structure is simulated by two-way fluid-structure coupling. With the control variable method, the simulation calculation of multiple groups of three-pipe structures under uniform incoming flow at different wind speeds is carried out. By analyzing the vortex kinetic energy diagram and displacement diagram, the best outer diameter and tube center distance of the three-tube structure to suppress vortex-induced vibration in the leeward direction are obtained. By summarizing the situation of a symmetrical vortex, the conditions of the symmetrical vortex are understood. Then, by comparing the amplitude of the vortex-induced vibration of the original structure with that of the three-tube structure, the three-tube structure is further optimized to obtain a new structural design that can effectively control vortex-induced vibration.
A New Flux Splitting Method and Central Difference Scheme for Magnetohydrodynamics
Authors: Zhang Shiyuan , Yang Wubing
Published: December 2022

In this work, we describe a new flux splitting method for an ideal MHD in the 3D curvilinear coordinate system. The method is designed to create a dissipation term by zero flux term of flux split and create a new central difference scheme for ideal MHD. Numerical tests are performed to demonstrate the accuracy and capability of the new scheme to capture complex waves of ideal MHD.
Mechanical Performance Analysis of Cable-Girder Anchorage Zone Structure Based on Hybrid Element Method
Authors: Lin Jinbiao , Huang Muyun
Published: December 2022

The finite element model of a partially cable-stayed bridge with a central single cable plane corrugated steel web composite box girder is established by the hybrid element method combined with the solid finite element model and spatial grid model, and the mechanical properties of cable-girder anchorage zone structure under cable forces are calculated and analyzed in this paper. The refined model of the steel anchor box structure was established, and the stress distribution of each component of the steel anchor box under cable force was calculated and analyzed. By calculating the resultant force of the cable direction in the junction area of each component, the ratio of the cable force transmitted by each component of the steel anchor box is obtained. The results show that the stress distribution of each component of the steel anchor box is uniform under the action of cable force, and the stress level of the shear plate and the steel guide beam is higher. It is an important component to transfer the cable force and should be the focus and research object in the cable beam anchorage structure.
Creep Effect on Chemo-Mechanical Coupling Oxidation of Thermal Barrier Coatings
Authors: Shen Qiang , Wu Leigang
Published: December 2022

In this paper, a chemo-mechanical coupling model considering the creep effect during high-temperature oxidation is developed based on the diffusion-reaction equation. A sinusoidal curve model is developed by the finite element method to simulate the thickness and stress distribution of thermally grown oxide (TGO). The thickness and stress distribution of the TGO in the thermal barrier coating was investigated by changing the coupling effect and creep effect conditions of the model. The results show that with the increase of the coupling coefficient, the thickness of TGO gradually becomes smaller. In the late stage of oxidation, this effect diminishes, and the compressive stress located in the BC/TGO layer groove keeps decreasing, while the tensile stress located in the TC layer groove is the opposite. As the creep rate increases, the maximum tensile/compressive stress in the Y-direction within the thermal insulation coating slowly decreases, and the oxidation rate of the oxide layer moderately decreases. This study is important to find the corresponding solutions and preventive measures for the failure of the thermal barrier coating.
Stability Analysis of Third-order Magnetic Gradient Tensor
Authors: Wang Bo , Ren Guoquan , Li Zhining , Cai Ziming
Published: December 2022

So far, magnetic gradient tensor has been studied in the field of exploration. The third-order magnetic gradient tensor(MGT) can obtain more target information. But its stability is poor. It will lead to a large error under the condition of noise. Aiming at the above shortcomings, this paper puts forward an improved method. The approximate calculation formula of the third-order MGT is analyzed and improved. It can be got from the simulation that the proposed method is more excellent.
Neighbor Sum Distinguishing Edge (Total) Coloring of Generalized Corona Product
Authors: Zhong Chuang , Tian Shuangliang
Published: December 2022

The coloring theory of graphs is an important part of graph theory research. The key problem of the coloring theory of graphs is to determine the coloring number of each kind of coloring. Traditional coloring concepts mainly include proper vertex coloring, proper edge coloring, proper total coloring, and so on. In recent years, scholars at home and abroad have put forward some new coloring concepts, such as neighbor vertex distinguishing edge (total) coloring, and neighbor sum distinguishing edge (total) coloring, based on traditional coloring concepts and by adding other constraints. Some valuable results have been obtained, which further enrich the theory of graph coloring.

For a proper [k]-edge coloring of a graph G, if for any adjacent vertex has a different sum of colors, then the coloring is a neighbor sum distinguishing [k]-edge coloring of G. For a proper [k]-total coloring of a graph G, if for any adjacent vertex has a different sum of colors, then the coloring is a neighbor sum distinguishing [k]-total coloring of G . In this paper, the coloring method and coloring index are determined by the process of induction and deduction and the construction of the dyeing method, and then the rationality of the method is verified by inverse proof and mathematical induction.

If G is a simple graph with the order n ≥ 5 , and hn
= (Hi
)
i∈{1,2,…,n} is a sequence of disjoint simple graphs, where every Hi
is a simple graph with the order m ≥ 7 . In this paper, we study the neighbor sum distinguishing edge(total) coloring of the generalized corona product G○hn
of G and hn
. The results are as follows:

(1) If G is a path with order n , hn
= (Hi
)
i∈{1,2,…,n} is an alternating sequence of path and cycle with order m . If n is odd, we have

χ
Σ
′

(

G
∘

h
n

)

=
m
+
3

(2) If G is a path with order n , hn
= (Hi
)
i∈{1,2,…,n} is an alternating sequence of path and cycle with order m . If n is odd, we have

χ
Σ

′
′

(

G
∘

h
n

)

=
m
+
4

Due to the late development of neighbor sum distinguishing edge (total) coloring of graphs, the related research results are relatively few. By studying the operation graph of a basic simple graph, we can provide the research basis and reference idea for the corresponding coloring of the general graph class. Therefore, it is of theoretical value to study the neighbor sum distinguishing edge (total) coloring problem of generalized corona products of graphs.
A Pattern of Prime Numbers and its Application in Primality Testing
Authors: Hang Peng , Sun Zhongquan , Wang Shanqin
Published: December 2022

Primes are so unique and elegant that each of them has only two factors (1 and itself), and natural numbers with this property are sparse. In this study, we present a pattern of prime numbers by proving that C

2x+3y=p
∈Q and C

2x+3y=c
∈G, where p denotes the prime numbers and c denotes the composite numbers. x and y count the quantity of number 2 and number 3, respectively. C

2x+3y=p
represents the channel of the function 2x + 3y = p. A channel is a trace of the function 2x + 3y = n in the first quadrant of the plane rectangular coordinate system. C

2x+3y=c
is similar. Q and G are two sets with different types of channels. The proposed pattern of prime numbers also provides a way for primality testing, which is of significance to public-key cryptography.
Propagation Pulses in Optical Fiber Modeled by the Kudryashov Equation
Authors: Li Chan , Wang Chunyan
Published: December 2022

Kudryashov equation describes the propagation pulses in an optical fiber. By using the trial equation method and complete discrimination system for the polynomial method, the classification of all envelope patterns of the Kudryashov equation is obtained, including solitary wave solutions, double periodic solutions, triangular function solutions, and rational function solutions. In particular, the conditions for the existence of each mode are given, and images of the modes are obtained according to the conditions.
Solving a Class of Nonlinear Evolution Equations Using Jacobi Elliptic Functions
Authors: Wang Bo , Jin Guiqin
Published: December 2022

Nonlinear evolution equations play a crucial role in many applied scientific disciplines. Finding the exact solutions to such equations can contribute to a wide variety of applied disciplines. To be able to calculate exact periodic solutions of nonlinear evolution equations, this paper discusses the expansion of the Jacobi elliptic function and finds the proper expansion of the function. Additionally, by analyzing the applicable conditions of the function according to its specific properties, we find the exact periodic solutions to nonlinear evolution equations with constant coefficients and variable coefficients that satisfy the applicable conditions of the Jacobi elliptic function.
Envelope Number of Irrational Number
Authors: Chen Gen-Fang
Published: December 2022

This paper proposes the concept of envelope numbers for irrational numbers, divides envelope numbers into upper envelope numbers and lower envelope numbers, and proves several important properties of such numbers. Firstly, the paper gives the uniform distribution theorem of irrational integer multiples. By proving several lemmas of upper envelope numbers and lower envelope numbers, it is proved that there are countless upper envelope numbers and lower envelope numbers of irrational numbers. At the same time, it is proved that the sum of the maximum upper envelope number and lower envelope number that does not exceed a given positive integer is also an envelope number.
An Involution about Fibonacci Numbers
Authors: Liang Dengxing , Yang Harold Ruilong , Zhang Yanjun
Published: December 2022

In “Proofs That Really Count” A. T. Benjamin and J. J. Quinn provided several identities involving Fibonacci numbers and left some unproven ones. They posed questions to find the combinatorial proofs of these identities. Among these identities, the following one caught our attention because of concerning parity:

∑

k
=
0

n

(
−
1
)

k

 

f
k

=
 
1
+

(
−
1
)

n

f

n
−
1

.

.

Krzykowski found that the coverings in an area with dimension 2 × n can be enumerated by Fibonacci numbers. In this paper, we give an involution throughout the interpretation of Fibonacci numbers given by Krzywkowski to explain the above identity and answer the question provided by Benjamin and Quinn.
A Novel Method of Computing Quadratic Weil Sum
Authors: Zhang Zhexing
Published: December 2022

Let χ be an additive character of F
q
and let L(x) be a linearized polynomial over F
qn. In this paper, we consider the Weil sums of quadratic functions, namely,

∑

x
∈

F

q
n

χ
(
T
r(
χ
L
(
χ
)
)

. Quadratic Weil sum is a critical topic in number theory and has applications in sequence design, coding, and cryptography. The computation of a quadratic Weil sum is complicated and sometimes impractical. This paper introduces a novel and generic way of computing quadratic Weil sums, which allows us to deal with the computation more efficiently compared with previous methods. As a result, we give a formula for computing

∑
​

x
∈

P

q
n

χ
(
T
r
(

∑
​

i
,
j
≤
n

a

i
j

χ

q
i

+

q
j

)
)

explicitly in the case aij
∈ Fq
. We also incorporate our results to obtain the condition for a class of Boolean functions to be bent, which are highly non-linear and widely applied in cryptography.
Staggered Discontinuous Galerkin Method for Singular Power-law Systems
Authors: He Qiqi
Published: December 2022

In this paper, we study singular power-law models of shear thinning, which is characterized by unbounded viscosity at the zero shear-rate limit, and we study the staggered discontinuous Galerkin method for p-Stokes type systems for p ∈ (1,2]. We use Picard’s iterate method to solve the correspondent nonlinear system. If p is very close to 1, when solving discrete nonlinear equations using the Picard method, numerical instabilities often occur. We give the numerical stability method of singular power-law system and some numerical experiments by reference [1].
Inequalities on the Fan Product of M-matrices
Authors: Zhong Qin , Mou Gufang
Published: December 2022

The research of M-matrix involving Fan product is an important topic of M-matrix theory research. Three inequalities on the minimum eigenvalue of Fan product are exhibited through the Perron eigenvectors of the M-matrices. The inequalities can be regarded as useful complements to existing research results.
Study on the Pipe–soil Interaction under Instability of Slope Based on Flume Experiment
Authors: Lian Jiangqiao , Shi Rui , Fan Rendan , Li Xianghui
Published: December 2022

To study the landslide of buried gas pipeline caused by rainfall, based on the flume experiment the laboratory model of rainfall-induced pipe–soil interaction of slope instability was established. By monitoring the cross-section strain of the pipeline under the slope instability induced by rainfall infiltration, the effect of soil on the pipeline is analyzed and calculated. The results show that the pipeline is located at different failure surfaces of the slope, which is affected by slope instability to different degrees. In the slope toe of apertures, ultimate cross-section strain is the largest, calculation of soil force and maximum limit 1515.535 N/m, and that of slope top pipe is 216.169 N/m, attenuation trend from toe to the top. Resultant force directions are distributed in soil and the horizontal angle is 68°. The results can provide reference and technical reserve for the study of pipe-soil interaction of buried natural gas pipelines under the action of landslide and the further improvement of pipeline safety.
Propagation Characteristics of SH Wave in Orthotropic Layer/Piezoelectric Column Structure
Authors: Li TaiSong , Wang YanHong
Published: December 2022

The propagation characteristics of SH waves along the circumferential direction in an orthotropic layer/piezoelectric column structure with a non-ideal interface are studied in this paper. By solving the governing equations, the solutions to the problem are expressed by the first and second Bessel functions. The dispersion equation is obtained by the boundary conditions and the interface conditions. The numerical examples are provided to show the effects of the degree of orthogonal anisotropy, the thickness-diameter ratio, and the imperfect interface on the dispersion characteristics.
Experimental Study on Emulsion Explosive Blasting under Different Under-Water Pressure
Authors: Liu Lei , Qi Hongyu , Zhang Haitao , Cai Yongzhi
Published: December 2022

This paper aims to study the effects of different water depths on the properties of emulsion explosives by use of an emulsion explosive underwater explosion test system for different hydrostatic pressure under the condition of 0.2% sodium nitrite sensitized emulsion explosive blasting model experiments. The results showed that the experiment designed by simulation of underwater explosion test equipment can be used in the explosive performance test sample in the compression state explosion. It can better simulate the explosive environment under different depth conditions. After blasting, the fractal dimension of concrete fragments decreases first and then rises with the increase of water pressure, and reaches an inflection point between 0.3 mpa and 0. 5mpa, which proves that water depth has a certain effect on the performance of explosives, and the effect is not linear distribution. This experimental study could provide a certain basis for subsequent research on underwater explosive characteristics of emulsion explosives.
Basic Introduction to Detectors of the Large Hadron Collider
Authors: Chen Xin
Published: December 2022

Particle physics is intended to explore the microscopic world, to be more specific, to understand the physical laws of particles. So far, the Standard Model (SM) is the best theory we have to explain particle properties and their behaviors. Such great success attributes to the data acquired from experiments in particle physics. These experiments not only provide evidence about the correctness of the SM but also reveal the limitations and what may be beyond the SM. Since microscopic phenomena cannot be observed by human eyes, it is necessary to use special instruments to do these experiments, and one of them is the Large Hadron Collider (LHC). This review shall introduce the basic information of the LHC and focus on the basic structure and principles of the detectors used in two experiment projects of the LHC.
Root Locus of Some High-order Polynomials
Authors: Xie Xing , Liao Zhihong , Yang Tianle , Zhang Jixian , Yang Zheng
Published: December 2022

For a third-order complex polynomial with its roots bounded by a circle, Marden’s theorem provides a useful way to evaluate the locus of its critical points. We construct a fourth-order complex polynomial by restricting its roots to ellipse and hyperbola. The locus of its critical points can be expressed by a formula. In addition, if the roots of complex polynomials are not restricted, their critical points will not occupy some regions.
Muon rate measurement under different thicknesses of Pb
Authors: Yang Zhekai , Dong Yiran
Published: December 2022

The major purpose of this paper is to analyze the rate of events under the different thicknesses of Pb on the top of two cosmic watch desktop muon detectors. The desktop muon detector is a simple, easy-built, and cheap cosmic ray muon detector. Using these detectors, the researchers experimented with different altitudes [2]. In this work, we concluded how the thickness of Pb above the detectors influences the rate of the muon. We placed one-on-top of another detector and changed the thickness of Pb above them. Using the python program, we analyzed a large number of data collected by the two desktop muon detectors systematically. We analyzed the relationship between the muon rate with the thickness and calculated the parameters. The result shows muon rate decreases exponentially as thickness increasing.
NACA0009 Hydrofoil Groove Design for Suppressing TLV and Noise
Authors: Zhou Yudi , Li He
Published: December 2022

In hydraulic equipment, tip clearance may result in a leakage vortex known as a tip clearance leakage vortex (TLV), which reduces the machinery’s energy efficiency. In order to lessen the damage brought on by tip clearance, this research sets the angle, location, spacing, and depth of the grooves as significant criteria. The orthogonal approach is used to design the hydrofoil’s grooves. Numerous simulations are carried out using the SST k-turbulence model and the wideband noise source model. The results demonstrate how closely the numerical simulation matches what was seen in the experiments. The results demonstrate that grooves are a successful method for lowering TLV when compared to the original hydrofoil. The vortex area of the hydrofoil is reduced by 4.15% under the M5 design compared to the original hydrofoil. The groove significantly alters the dipole noise distribution of the hydrofoil’s leading edge in comparison to the original hydrofoil, resulting in a reduced decibel noise level at the hydrofoil’s tip clearance region. In comparison to the original hydrofoil, the average Curle APL of M5 and M8 decreased by 1.78 and 1.65%, respectively. Due to the way the groove blocks the TLV and muffles the noise it generates, M5 is in the optimum operational condition.
Optical Properties of Single-walled Carbon Nanotubes
Authors: Zhang Liyun , Zhou Ying , Zhang Na , Zhang Miao
Published: December 2022

In this paper, a series of single-walled carbon nanotubes’ optical properties are researched by using the ABINIT software package. The results show that the dielectric function and absorption coefficient of carbon nanotubes are related to both their geometric structure and their electronic structure. This has a guiding role for the further research of the optical properties of doped carbon nanotubes, carbon nanotubes with defects, and carbon nanotube arrays.
Study on the Asymmetric Separation Characteristics of Slender Body at High Angle of Attack under Lateral Jet Conditions
Authors: Zhang Xiaoliang , Cao Ning , Ni Zhaoyong , Li Suxun
Published: December 2022

The slender body is selected as the shape of the study. The effects of lateral jet flow at M∞ = 0.3, 0.6, 0.8 on the asymmetric separation characteristics of the body at large angles of attack are numerically simulated. To obtain the deterministic asymmetric separation results of the slender body, the artificial disturbance is carried on the tip of its head. The aerodynamic characteristics of asymmetric separation in jet-off and jet-on conditions are obtained, and the effects of Mach number, Angle of attack on asymmetric separation flow behaviors of the slender body are analyzed.
Implementation of Artificial Compressibility Method for Steady and Unsteady Incompressible Flows Based on Finite Volume Method of Unstructured Grids
Authors: Wang Hao , Wang Jianhua , Liu Yanming
Published: December 2022

The development of a new computational fluid dynamics solver for simulating incompressible flows is described. Unlike traditional pressure-based solvers, the artificial compressibility method simulates both steady and unsteady states. Some classical numerical examples are used to validate the solvers. These findings show that the artificial compressibility method’s LES/DNS and steady flow simulations are competitive with the best previously reported methods. The following characteristics make this paper unique: (1) We implement the artificial compression method in OpenFOAM for the first time and show the detailed mathematical process of the algorithm so that readers can easily reproduce and improve it; (2) steady flow simulation case, the convergence time of the present method is 52% of the pressure base solver; (3) to accelerate the convergence rate of each time step to the incompressible state, the L-stable Singly Diagonal Implicit Runge-Kutta method is introduced into the pseudo-time advance, which enlarges the limit of maximum Courant number to accelerate convergence.
Sensitivity Analysis of Random Parameters for Earthquake Response of Hakka Tulou in Fujian
Authors: Yang Chunyan , Liu Qiang , Pang Shangbin
Published: December 2022

The seismic response analysis of the Fujian tulou structure considers the influence of six input random variables of the tulou structure. It obtains the seismic response of the apex displacement, the maximum inter-story displacement angle, and the base shear force of the tulou structure. An analysis method based on moment-independent importance measure is proposed and applied to the stochastic parameter sensitivity (importance measure) analysis of structural seismic response. The results show that the importance metric analysis method of the seismic response of the structure based on the moment-independent importance measure analysis method generates consistent outcomes with the importance measure method of the variance. However, the method in this study can better reflect the actual earthquake response of the tulou structure, and it is also an efficient method.
Application of Coupled Coordination Model in Development Evaluation of Station Area
Authors: Lv Qingwen , Shi Jianren
Published: December 2022

“Coupling” was originally a physical concept, and gradually extended to other professional fields due to its good applicability. Coupled coordination mathematical models and calculation methods are gradually formed and applied in empirical research. We apply the coupled coordination model derived from mathematical methods to the development evaluation of the station area. In this process, we try to improve the accuracy of the analysis results by analyzing the applicability of the model, adjusting the coefficient, and establishing the indicator system. Finally, all stations of Hangzhou Metro Line 5 are selected as the empirical objects. The analysis results show that in terms of the coupling and coordination degree between the transportation and the development of surrounding areas, the stations located in the center of the city are better than the stations at the edge of the city. However, under the influence of the development strategy and transfer attributes, the coupled coordination degree of some stations is higher than that of their neighboring stations. The station-centric transportation design and land use are beneficial to the development of station areas. In addition, the accuracy of the analysis process can be improved by using the coupled coordination model.
Lagrange’s Theorem in Group Theory
Authors: Cui Can , Gan Chenqin , Ren Changwang , Mo Zhangying
Published: December 2022

The structure and behavior of molecules and crystals depend on their different symmetries. Thus, group theory is an essential technique in some fields of chemistry. Within mathematics itself, group theory is very closely linked to symmetry in geometry. Lagrange’s theorem is a statement in group theory that can be viewed as an extension of the number theoretical result of Euler’s theorem. It is seen as a significant lemma for proving more complicated results in group theory. The main intention of this dissertation is to prove Lagrange’s theorem which illustrates that every quadratic irrationality has a periodic continued fraction. Conversely, every periodic continued fraction is a quadratic irrationality. The first part of this paper is the research of so-called Dirichlet groups, which are subgroups of preserving certain pairs of lines. These groups are closely related to the periodicity of sails. The structure of a Dirichlet group is induced by the structure of the group of units in order. Taking n-th roots of two-dimensional matrices using Gauss’s reduction theory will also be shown. Finally, the solutions of Pell’s equation and Lagrange’s theorem will be proved.
Seismic response characteristics and optimization analysis of large-span pipe bridge
Authors: Qi Yong-feng , Gong Ya-qi , Qin Xi
Published: December 2022

The large-span pipe bridge is widely applied to long-distance water diversion projects because of its large crossing capacity, strong integrity, and adaptability to complex terrain. However, under the action of an earthquake, the pipe bridge will often produce large displacement, which can lead to large deformation of the whole system and damage to the pipe bridge structure. At present, there are relatively few studies on the seismic response of such pipe bridges for water diversion, and even there is also a lack of special design specifications for pipe bridges. Combined with the construction practice of the KLH long-span pipe bridge, based on the finite element analysis, the seismic response characteristics and dynamic stabilization of the long-span pipe bridge are analyzed, so the structure optimization scheme is proposed for the key parts of the bridge. The research results can provide new ideas for the seismic design of the long-span pipe bridge.
Study on the Influence of Special Vehicle Locking Mechanism on Protective Performance
Authors: Bai Jianing , Zhou Yunbo , Zhang Ming , Cheng Zhibing , Liu Jiazhi , Tao Rui
Published: December 2022

In order to study the influence of various structural dimensions of the suspension floor locking mechanism on the vehicle protection performance of the special vehicle suspension floor, the finite element simulation analysis and structural optimization design of the locking mechanism are carried out. The starting load of the locking mechanism based on the occupant damage threshold was determined, the dynamic tensile loading system of the locking mechanism was designed, the accuracy of the design scheme and the finite element model was verified, and the experimental design was carried out using Latin hypercube sampling. In addition, the sensitivity analysis was carried out, the relationship between the structural size of the locking mechanism and the protective performance of the vehicle was clarified, the optimal mathematical model of the locking mechanism was established, and the Pareto solution set of the optimization model was obtained through the multi-objective genetic algorithm. The optimal design scheme of the locking mechanism was obtained by using the linear multi-criterion decision method, and the accuracy of the optimal scheme was verified by the simulation.
Analysis of Eclipsing Binary Stars and Identification of Exoplanets Using Transit Timing Variation Using data from TESS
Authors: Lo Tinfei , Fu Jiani
Published: December 2022

This study uses openly available TESS (Transiting Exoplanet Sky Survey) data to detect evidence for potential exoplanet transits in an eclipsing binary system. Using the Python transit light curve analysis package lightcurve, we discuss the characteristics of an eclipsing binary star’s light curve in determining the classification of a system. In addition, we also study phenomena on a light curve that indicates the existence of a potential exoplanet. Although this investigation yields null results and finds no conclusive evidence, suggesting the presence of exoplanet transits in known eclipsing binaries using TESS data, we explored in depth the physical properties of binary star system TIC 7720507, identifying strong methods for explanatory stellar research.
Frequency Division Design of Multi-Unit Moving Iron Earphone
Authors: Li Xuexia , Fan Yuchao , Lu Yuyue
Published: December 2022

A high-quality earphone with multiple sound-generating units and frequency-dividing circuits, with a core of sound-generating units consisting of multiple balanced armature units, aided by analog frequency-dividing circuits and an earphone shell made of light-cured resin, is designed. The whole project of physical production is realized. The analysis results of the earphone frequency response curve, which are obtained with the help of a frequency response tester, show that the production of headphones in sensitivity, frequency response curve stability, transient response, and many other aspects achieved the expected sound quality effect.
Applications of Group Theory
Authors: Tang Dongxian , Wang Zichang , Yue Bangning
Published: December 2022

Groups play a fundamental role in Abstract Algebra: many algebraic structures, including rings, fields, and modules, can be seen as formed by adding new operations and axioms based on groups. Researchers often use group theory to explain many kinds of phenomena. In recent years, group theory has been introduced into crystallography to further explore the macroscopic symmetry of crystals from a mathematical point of view. In this paper, the applications of group theory in crystallography and magic cubic will be discussed. Basic definitions and models of these fields are demonstrated. A finite group is a group with a finite number of elements, which are the important contents of group theory. Besides, this paper proves that n−1 elements in a n order group can completely decide the nth element and gives a method of the nth element in a commutative group of order n. The analysis suggests that the research method of group theory has an important influence on other subjects.
Experimental Study on the Influence of Heavy Mud Pollution on Tight Sandstone for Deep Wells
Authors: Liu Hui , Liu Hongtao , Qin Shiyong , Ren Dengfeng , Wen Zhiming , Liu Yuxuan
Published: December 2022

Heavy mud pollution tends to occur during the workover of deep tight sandstone gas wells in Tarim, resulting in a significant reduction in gas well production. In order to study the impact of heavy mud pollution in deep sandstone gas reservoirs in the Tarim Basin, the physical properties and mechanical parameters of cores before and after heavy mud pollution were tested by non-destructive testing methods such as porosity, permeability, and acoustic waves. The results show that after the matrix core is polluted by heavy mud, the overall damage of permeability is ≥60%. Low-density mud causes more damage than high-density mud. The effect of increasing displacement time on permeability damage is higher than that of increasing displacement pressure. Heavy mud has an obvious influence on matrix porosity, but with the change in displacement pressure and displacement time, the change in core porosity has no obvious regularity. After the matrix core is polluted by heavy mud, the Poisson’s ratio increases by about 70% on average, but the change in elastic modulus is small, only -1.15%−4.25%. The experimental results provide significant guidance for reservoir damage assessment of mud-contaminated wells in Tarim.
Suspension Parameters Optimization of Fast Freight Wagon Based on Low Wheel-Rail Dynamic Interactions
Authors: Li Zhenhua , Wang Chao
Published: December 2022

The dynamic model of fast freight wagon is established to study the effect of key parameters of the freight wagon on dynamic performance. In order to reduce the wheel-rail dynamic interactions, the parameters such as primary suspension stiffness, arm joint stiffness, and joint stiffness of the anti-yaw damper are optimized. The results indicate that the above suspension parameters have an influence on the fast freight wagon’s dynamic performance. Compared with the simulation results of the original parameters, the wheel-rail vertical force is reduced by 10%, and the wheel-rail lateral force is reduced by 42% and 38% respectively under the straight and curve conditions of the empty vehicle. The wheel-rail vertical force is reduced by 10% and 6%, and the wheel-rail lateral force is reduced by 10% and 16% respectively under the straight and curve conditions of the loaded fast freight wagon. The running stability and safety of the fast freight wagon have been improved.
Effect of intercritical quenching on microstructure and properties of DP980 steel
Authors: Fan Yixuan , Li Liejun , Peng Zhengwu , Gao Jixiang , Ren Jianping
Published: December 2022

The increase in the number of cars leads to an increase in energy consumption, so the trend of automotive lightweight is more and more obvious, and DP steel with its excellent strength and plastic fit, high-cost performance, and other advantages in a long time is still the main material with high strength and high performance for automobiles. The effect of quenching temperature and soaking time on the microstructure and properties of DP980 steel in the critical quenching and tempering process was studied. The results show that martensite structure occurs when the quenching temperature is 760°C, and the volume fraction of martensite is 32% when the quenching temperature is 780°C. At 720°C to 780°C, the product of strength and ductility of DP980 steel increases with the increase of quenching temperature. The focus of future work is to find the appropriate quenching temperature and the Soaking time, on the basis of reaching the strength requirements, to get the best comprehensive mechanical properties.
Preparation and photocatalytic properties of Bi2MO6 (M =W, Mo) semiconductor composite TiO2 nanowires
Authors: Shangguan Tiantian , Liu Shikai , Song Zhijian , Liu Keke , Yang Xingyuan , Li Tengfei , Deng Haonan
Published: December 2022

Photocatalytic degradation of pollutants using nano-TiO2 is one of the most promising strategies to solve environmental pollution problems. In this paper, we systematically studied Bi2WO6 composited TiO2 nanowires to obtain the optimum composite proportion. Moreover, the TiO2 nanowires were composited with Bi2MoO6 and Bi2WO6/ Bi2MoO6 in the optimum proportion, respectively. The results showed that the Bi2WO6/ Bi2MoO6 composited TiO2 nanowires had the best catalytic performance, and the degradation rate of methyl orange reached 78.4%, which was 3.41 times higher than that of pure TiO2 nanowires. The current work is expected to provide new ideas for the research and development of high-efficiency photocatalytic materials.