bluuebunny/crossref_metadata_2025_split huggingface dataset:
Using Cauchy theorem to compute complicated real integrals
Authors: Song Jiarui , Shi Zhanhua , Wang Haotao 
Published: September 2021

Abstract
As the central object in the theory of complex analysis, Holomorphic functions have many elegant mathematical properties. Holomorphic functions are extremely valuable because, on the one hand, they are unexpectedly common, and on the other hand, they may be used to establish extremely powerful theorems. For example, To establish theorems like the prime number theorem, analytic number theorists commonly create holomorphic or meromorphic functions that hold number-theoretic information, such as the Riemann zeta function. Given knowledge about a holomorphic function in a relatively small part of its domain, one may extract information about the function’s behavior in other a priori unrelated sections of its domain, according to Cauchy’s integral formula and the identity theorem (and this is what allows things like contour integration to work). Due to difficulties in obtaining primitives of some real function, the fundamental theorem of Calculus does not work in most cases. In this article, we review the Cauchy theorem and use it as a tool to compute several real integrals.
Entire function which shares two distinct finite values IM with two of its difference operators
Authors: Li Sheng , Yang Peihao , Wang Songmin 
Published: September 2021

Abstract
Suppose that

F

≡

0

is an entire function with hyper-order

σ
2

(
F
)
<
1

and

m
,
n
(
n
>
m
≥
1
)

are two integers. If

F
,

Δ
η
m

F

and

Δ
η
m

F

share two values IM, then either

F
≡

Δ
η
m

F

or

Δ
η
m

F
≡

Δ
η
m

F

. Moreover, if n = km for some integer k ≥ 2, then

Δ
η
m

F
≡

Δ
η
m

F

.
Research on Furnace Temperature Curve Based on Linear Regression Model
Authors: Xue Jianting , Wei Xuerong , Liu Qiang , Mao Yuanyuan 
Published: September 2021

Abstract
With the rapid development of social science and technology, various industries have higher and higher requirements for the quality of electronic products. SMT surface mount technology is the most popular process in the electronics assembly industry, and reflow soldering is one of the SMT mounting processes. Reflow soldering is mainly used to solder the circuit boards with components already attached. The solder paste is melted by heating to fuse the chip components and the circuit board pads together, and then the solder paste is cooled by the cooling of the reflow soldering, and the components are soldered. The plates are solidified together, and the furnace temperature curve records the temperature changes of the circuit board during this process. This article focuses on the printed circuit board welding production problem, through optimizing the furnace temperature curve for high-efficiency and quality-guaranteed production, and researches on the changes of the furnace temperature curve at different temperatures.
Optimality Conditions for Multiobjective Programming under Generalized Uniform (V, η)-type I Symmetrical Invexity
Authors: Ruijie Wang 
Published: September 2021

Abstract
Multi-objective optimization is a major branch of the optimization category. On the basis of (V, η)-I symmetric invariant convex functions, the concept of generalized uniform (V, η)-I symmetric invariant convex function is proposed. Which is generalized uniform (V, η)-I type. Under the new generalized convexity hypothesis, several optimality sufficient conditions for multi-objective programming are proved.
Stability analysis for semi-linear stochastic differential equation with piecewise continuous arguments
Authors: Zhang Ling , Cheng Qian-mu , Liu Guo-qing , Wu De-lin 
Published: September 2021

Abstract
In this paper, the exponential stability in mean square of the exponential Euler method for semi-linear stochastic differential equation with piecewise continuous arguments is obtained. Firstly, the exponential Euler scheme of the equation is given. Secondly, under Lipschitz condition, sufficient conditions of exponential stability to the exact solution are achieved in mean square. Furthermore, it is proved that exponential Euler method preserves exponential stability of the exact solution without any restriction on the step-size. Finally, an example is provided to illustrate our theories.
Numerical Simulation of Flow Field in the Laval Nozzle Based on Euler Equation
Authors: Zhang Zewei , Yi Baozhao , Tan Zhexuan 
Published: September 2021

Abstract
A nozzle is a versatile fluid device that is utilized to control the characteristics of a fluid flow. In order to enhance the performance or better the design of the nozzle, it is critical to carry out extensive research into its inner flow. Thus, the investigation of the nozzle flow remains an important challenge. This article used a numerical simulation method based on Euler equations to solve the internal flow of the divergent, convergent-divergent, and convergent nozzles. Specifically, we simplify all three equations of the one-dimensional Euler equation (the continuity equation, the momentum equation, and the energy balance equation) by assuming a constant nozzle shape, then discretizing them using a central differential scheme. After conducting systematic research on the influence on the internal nozzle flow due to the change of nozzle shape, we found that the mass flow rate varied as it fluctuated and peaked at the middle point of the Laval nozzle. However, with the nozzle becomes flatter, the mass flow rate appeared to restore conserved. Moreover, it appeared that the flatter the Laval nozzle is, the smaller acceleration and smaller decrease of the pressure of the fluid flow gets. In short, the results suggested that it is dependable to apply this numerical method when analysing a relatively flat Laval nozzle.
Research on the reaction-diffusion equation with Robin and free boundary condition
Authors: An Ran , Tian Shifang , Liu Xiaowei 
Published: September 2021

AbstractThe free boundary value problem of reaction-diffusion equation is studied. In the first chapter, the Logistic diffusion equation with free boundary and the main work of this paper are introduced. The second chapter is the preparation work, explaining the existence and uniqueness of the solution of the free boundary Logistic diffusion equation. In the third chapter, we prove that messages propagate or disappear in finite time by constructing the asymptotic properties of upper and lower solutions. In chapter 4, the criterion of diffusion disappearance is given, and the threshold of information propagation or disappearance in finite time is given according to the initial value. The results show that when the given value is larger than the threshold value, the information will propagate in the whole region. Otherwise the message will stop propagating for a limited time.
Comparative studies on two dimensional VCl2 and VBr2 as anodes of Li ion batteries
Authors: Wu Yidan 
Published: September 2021

Abstract
Lithium-ion battery, one of the most commonly used portable power supply devices, still has many drawbacks, such as low rate of charging and discharging, poor safety and low energy density. Through using the appropriate two-dimensional (2D) anode materials, the performance of lithium-ion batteries (LIBs) can be greatly improved. In this study, through first principles calculation, we compare two 2D materials as anode materials, VCl2 and VBr2, and we find that: (1) VCl2 cannot stably adsorb lithium, because lithium breaks down the original crystal structure of VCl2; (2) VBr2 not only adsorbs lithium stably, but also has good properties of voltage, conductivity and diffusion barrier. Given these advantages, VBr2 is predicted to be promising for being applied as an anode material of LIBs. It is hopeful that this study has a guiding significance for the research and development of two-dimensional materials as battery anode materials.
Application of stereo PIV to the 70° delta wing at subsonic speed
Authors: Wei Chunhua , Zuo Chenglin , Liang Lei , Yue Tingrui , Cheng Yong 
Published: September 2021

Abstract
A stereo PIV technique is utilized for the analysis of the flow field over a 70° delta wing. Instantaneous velocity vectors are measured at a series of stations in the chordwise direction. The angle of attack from 0° to 45° are investigated with the free stream velocities of 20, 30, 40, 50 and 60 m/s, respectively. The velocity measurements conducted in a small-sized subsonic wind tunnel (1.8m×1.4m) at China Areodynamics Research and Development Center (CARDC) are compared with the previously obtained PSP results. The comparison shows a good agreement with each other, providing the validity of the PIV technique as well as indicating its effectiveness to investigate complex flow fields in a fairly large-scale wind tunnel facility.
A study of the relationship between comets and solar activity
Authors: Chen Haokang , Xiao Tianyang , Xu Yang , Yang Na , Zhuang Qiangjian , Cao Zexin 
Published: September 2021

AbstractIt is suggested that some comets originated from solar activity and were ejected by the sun in late period. In order to verify this point of view, the new star ejected from the sun’ s surface is regarded as a particle, and the orbital evolution problem is simplified to the problem of a particle moving around a sphere, whose motion is disturbed by the asteroid belt and planets. By analyzing the influence of gravity, Coriolis force and viscous force on the trajectory of the new star, the trajectory of the new star is obtained. The results show that the orbits of small objects ejected from the surface of the sun are very similar to those of comets, which also explain the rotation of comets along the direction of the sun’ s rotation, etc., indicating the physical rationality of the comet hypothesis.
Research on Mechanism and Application of Coriolis Acceleration
Authors: Wang Feng , Ma Yurong , Jiang Yaqiong , Li Dan , Li Haixia 
Published: September 2021

Abstract
Chongqing Bus falling into the river shocked the whole country. In order to find out whether the Coriolis illusion is one of the real causes of Chongqing Bus falling into the river, the mechanism of Coriolis acceleration is studied, and the corresponding analysis of the phenomenon caused by the Coriolis acceleration is carried out. The driver’s head in Chongqing Bus falling into the river is modelled and calculated. It is concluded that the effect of Coriolis acceleration can be ignored when the object’s motion speed is low, that is, the main cause of Chongqing Bus falling into the river is not Coriolis illusion.
Tensions between measurements of the Hubble constant from the early and late Universe
Authors: Su Xiaolei 
Published: September 2021

Abstract
Hubble constant (H0) is one of the most important parameters in cosmology. There are mainly two ways to determine the value of Hubble constant, which measure the properties of early universe and the late universe, namely cosmic microwave background radiation (CMB) and Type Ia supernovae (SNe Ia). Those who had used these two methods to measure the Hubble constant won the Nobel Prize in Physics respectively, in 1978 and 2011. This article introduces the principle of accelerating universe and the methods to measure the Hubble constant. We analyze each method and discuss the uncertainties of them. In addition, we investigate possible reasons for Hubble constant discrepancy based on previous studies. We discuss about the conclusion and prospects of Hubble constant measurement.
“The Reddish Moon”--The Evaluation of Urban Air Pollution by Lunar Extinction
Authors: Xinming Shen 
Published: September 2021

Abstract
In severe polluted areas, objects tend to be redder because of the refraction of light by particulate pollutants through the atmosphere. In this study, a particle scattering model is established to simulate the scattering of pollutants based on assumptions. Then the actual data of lunar extinction is obtained by using an astronomical telescope to measure the RGB color differentiation at different altitude angles of the lunar surface in Shanghai caused by pollutants scattering. The results are combined with the particle scattering model calculation to obtain the estimated pollutant thickness in the atmosphere.
The Relationship Between Time and Space
Authors: Wu Guanzheng 
Published: September 2021

Abstract
The relationship between time and space has been studied by people for a long time. Although it is still in a development stage, it is necessary to be researched. This paper aims to introduce the space-time relationship from classical physics to modern physics. Subsequently, the author analyses Galilean transformation and its limitations to lead naturally to Lorentz transformation. After that, the special relativity is shown by giving some examples. Special relativity is based on two postulates, including the Principle of Relativity and the Principle of Invariant Light Speed. Mickelson-Morley experiment and mass-energy equivalence can explain the Principle of Invariant Light Speed well. The paper then introduces intuitively Minkowski spacetime, which can help readers understand four-dimensional spacetime as well. In addition, the distinctions of different dimensional spaces will be mentioned. The essay also discusses the general relativity that time is also affected by gravity and the principle of equivalence, but it’s really only a quick cheat-sheet summary. Finally, this paper points out the possibility of reaching the speed of light, and if it can be achieved, spacetime will be changed so that lots of unbelievable consequences will come one after another. The article draws a conclusion that time and space are like a whole, one change makes all change.
A novel construct for scaling groundwater–river interactions based on machine-guided hydromorphic classification
Authors: Hou Zhangshuan , Ren Huiying , Murray Christopher J , Song Xuehang , Fang Yilin , Arntzen Evan V , Chen Xingyuan , Stegen James C , Huang Maoyi , Gomez-Velez Jesus D , Duan Zhuoran , Perkins William A , Richmond Marshall C , Scheibe Timothy D 
Published: September 2021

Abstract
Hydrologic exchange between river channels and adjacent subsurface environments is a key process that influences water quality and ecosystem function in river corridors. Predictive numerical models are needed to understand responses of river corridors to environmental change and to support sustainable watershed management. We posit that systematic hydromorphic classification provides a scaling construct that facilitates extrapolation of outputs from local-scale mechanistic models to reduced-order models applicable at reach and watershed scales. This in turn offers the potential to improve large-scale predictions of river corridor hydrobiogeochemical processes. Here we present a new machine-guided hydromorphic classification methodology that addresses the key requirements of this objective, and we demonstrate its application to a segment of the Columbia River in the northwestern United States. The resulting hydromorphic classes form spatially coherent and physically interpretable hydromorphic units that exhibit distinct behaviors in terms of distributions of subsurface transit times (a primary control on critical biogeochemical reactions). This approach forms the basis of ongoing research that is evaluating the formulation of reduced-order models and transferability of results to other river reaches and larger scales.
Are soil sealing indicators sufficient to guide urban planning? Insights from an ecosystem services assessment in the Paris metropolitan area
Authors: Tardieu Léa , Hamel Perrine , Viguié Vincent , Coste Lana , Levrel Harold 
Published: September 2021

Abstract
Urban sprawl impacts are critical in the evaluation of planning decisions and often monitored by indicators of soil sealing. In France, these indicators are required by law to be reported in environmental assessments of planning documents. Although monitoring of soil sealing is important to limit environmental impacts, focusing on this sole dimension in urban planning can be reductive. In this paper, we explore to what extent ecosystem services (ES) indicators, measuring the benefits to humans provided by healthy ecosystems, are captured by soil sealing indicators by comparing their temporal and spatial evolutions. Through consulting with urban planning stakeholders, we model and map the spatial and temporal evolutions over a 35 year period of soil sealing and eight priority ES in the Paris metropolitan area (agricultural potential, groundwater recharge, global climate regulation, water quality regulation through nutrient retention, urban heat mitigation, flood mitigation, recreational potential and natural heritage). We highlight the spatial and temporal matches and mismatches between the two types of indicators (ES and soil sealing) and demonstrate that a large part of ES variations are not well captured by soil sealing indicators in time and space (spatial match with the eight ES is only found for 10% of the Paris metropolitan area). This calls for finer, ES-based, diagnosis in land use planning that could usefully illuminate the gains and losses related to land use and land management policies by taking into account the environmental and societal impacts of urban sprawl.
Development of Ishikawa Diagram of Oil Spreading in the Sea
Authors: Hlevnjak T , Dmitrović L Gotal , Čerepinko D 
Published: September 2021

Abstract
The spread of an oil slick over the water surface is a complex process that is systematically described by the Ishikawa diagram. An oil slick moves across the surface under the influence of forces acting on every particle in the sea. The development of the Ishikawa diagram describes the causes, sub-causes, sub-sub-causes… to level 5th causes. Consequence, i.e. the problem in this case, in Ishikawa diagram is spreading oil slicks in the sea. Theoretical framework for development of the Ishikawa diagram defined through mathematical equations shows that the spreading of oil slicks in the sea depends on sea pressure, friction force, Coriolis force, buoyancy force, equation of state, tangential stresses due to wind action (wind currents), tidal forces, tension force and diffusion.
Productivity Analysis of Municipal Solid Waste Collection in Italy using SBM DEA Malmquist Index
Authors: Storto C lo 
Published: September 2021

Abstract
This paper presents a productivity analysis of municipal solid waste collection in Italian provinces from 2010 to 2019. Particularly, the total factor productivity was measured by computing the non-parametric Global Malmquist Productivity Index implementing Slack Based Measure Data Envelopment Analysis (SBM-DEA). Findings show that the productivity of the sorted waste collection service slightly grew from 2010 to 2019. Such growth was due to an increase of the technical efficiency and an improvement of the service technology. However, in some years the efficiency changes and productivity increase were affected by the rise of the per capita production of waste.
The Productivity and Profitability of Marshland Farming System: the Case of Ligawasan Marsh in Maguindanao
Authors: Buisan NA , Roxas AT 
Published: September 2021

Abstract
Wetlands have been used for agriculture because of their natural fertility. This is true in Ligawasan Marsh in Southern Philippines where residents have been farming as main source of livelihood. This study determines the productivity and profitability of rice, corn and mungbean as primary crops in a marshland community in Maguindanao. It was conducted during dry season combining quantitative and qualitative design. Triangulation method was applied using survey, key informant interview, focus group discussions and observation. There were 24 farmers who participated in the study. The average yields for rice, corn and mungbean were at 1.5 t ha−1,.78 t ha−1, and 0.32 t ha−1, respectively. Farmers earn Php 13,860.65 per ha for rice, 3,933.56 for corn, and Php 12,898.83 for mungbeans. Productivity and profitability is low compared to established data on yield and net income. Farmers, however, are spending very minimal which make them less dependent from external input. The average cost of production is lower than the established production cost. Farming in a marshland community is considered as low external input agriculture. There is a need to diversify farmers’ income including vegetable gardening, duck raising, and fishing and adopt a better cropping calendar.
Strengthening Food Security During The Covid-19 Pandemic: Case Study In Temanggung District, Central Java Province, Indonesia
Authors: Kurnaedi Dede , Purnomo Eko Priyo , Salsabila Lubna , Setiawan Deni , Fathani Aqil Teguh , Agustiyara  
Published: September 2021

Abstract
The purpose of this research is to find out what policies are taken by the Temanggung Regency Government in fighting for community food security. The Covid-19 pandemic that hit Indonesia, especially Temanggung Regency, had a significant impact in increasing the unemployment rate, which was not in line with the increased nutritional needs of the community, so the government made efforts so that people could meet their regular food needs or primary needs. The method used is a qualitative research method with a descriptive approach; the data collected are primary data and secondary data obtained from the Food Security, Agriculture and Fisheries Office of Temanggung Regency through in-depth interviews conducted in March 2021. Meanwhile, secondary data were obtained from literature, media and other relevant sources. The results obtained were that the Temanggung Regency Government implemented a community empowerment policy to organize yard farming for the community at the village level targeting low-income families and farmer groups with government funding aimed at making the community at least able to meet their daily food needs. During the Covid-19 pandemic, family needs through the use of the yard or the surrounding environment without having to spend money.
Synthesis and Application in Photocatalytic Hydrogen Production of Layered MoS2
Authors: Qiu Kaiwen 
Published: September 2021

Abstract
With the consumption of energy and the destruction of the environment by mankind, mankind is now facing a serious energy and environmental crisis. In order to solve this situation, photocatalytic hydrogen production from water will become an effective way. MoS2 shows a good potential for photocatalytic hydrogen production, and the research in this paper will help to develop efficient photovoltaic hydrogen production materials. Two-dimensional MoS2 is a layered transition metal compound similar to graphene. For its advantages, such as large specific surface area, suitable band gap, high catalytic activity of hydrogen evolution by edge suspension bond and strong photocorrosion resistance, it shows good application potential in photocatalytic hydrogen production. This paper summarizes the research progress of layered MoS2 in photocatalytic hydrogen production in recent years. The preparation method of two-dimensional layered MoS2, the structure and properties of MoS2, and the application of the composite system formed by MoS2 and other semiconductor materials in photocatalytic hydrogen production are introduced. Besides, the author discussed the development prospects of MoS2.