bluuebunny/crossref_metadata_2025 huggingface dataset:
Study on axial compression behavior of rectangular concrete filled steel tubular columns with Perfobond Leister Ribs
Authors: Cheng Hanjian , Lu Zheyuan , Cao Xinke
Published: September 2021

The built-in open-hole type stiffened rectangular steel tube concrete refers to a new combined structure formed by forming an open-hole steel plate in the longitudinal direction of the inner wall of the steel pipe and then filling the concrete. The PBL stiffener has the double functions of longitudinal stiffener and shear connector. In order to study the influence of stiffeners on the ultimate bearing capacity of rectangular CFST columns, the finite element model was established by ABAQUS and the parameters of the stiffeners were analyzed, including the aperture of the stiffeners, the spacing of the stiffeners and the width-thickness ratio. The results show that the finite element model established in this paper is in good agreement with the existing test data. The bearing capacity of rectangular CFST columns increases first and then decreases with the increase of the opening aperture of stiffeners, increases with the increase of the opening spacing, and increases with the decrease of the width to thickness ratio of stiffeners. The conclusions of this paper can provide some suggestions for the design of PBL stiffened rectangular CFST columns in practical engineering.
Research on Application Effect Evaluation of Steel Box Girder Bridge Based on Combination Weighting
Authors: Zhang Lin-jun , Zhou Hongwen , Li Heng , Yuan Baoyue
Published: September 2021

At present, the research on the application effect of steel box girder bridges is still only in the qualitative analysis link, and the calculation of index weights is greatly affected by personal subjective factors, and the quantitative evaluation of the application effect of steel box girder bridges has not been achieved. In this paper, we proposes a combination of subjective and objective combined weighting fuzzy evaluation model, which avoids the unreasonable problem of a single weighting method in determining the weight coefficients, and makes the weight distribution results more accurate and effective. Among them, the coefficient of variation method and the AHP method are used to calculate the subjective and objective weights of the indicators, and the linear combination calculation method is used to determine the comprehensive weights of the indicators. Then, combined with the fuzzy evaluation model, a comprehensive analysis of the application effect is carried out. Finally, the effectiveness of the combined weighting evaluation model is verified with a practical project case.
Applications and Advances in TiO2 Based Photocatalytic Building Materials
Authors: Liu Chongyang , Bai Jitao , Zhang Simiao , Yang Zewen , Luo Ming
Published: September 2021

TiO2 is currently the most widely used photocatalytic material. Compared with traditional building materials, TiO2-based photocatalytic building materials have unique and significant advantages, which endows them with great potential in application. By summarizing the current application and research status of photocatalytic building materials, the existing problems of photocatalytic building materials and corresponding solutions were pointed out, and current research progress of photocatalytic building materials in terms of carbon emission reduction in buildings was introduced. Finally, some prospects were made on photocatalytic building materials, which would provide a reference for the study on the next generation of photocatalytic building materials.
A dual-narrow-band near-infrared perfect absorber based on a crossed double nanorods metasurface
Authors: Guo Ling , Guo Mengran , Liu Yajie , Yin Shan
Published: September 2021

Perfect absorbing materials have attracted the attention of researchers because of their wide application in solar photovoltaic industry, biosensor and filter. Here, we report on our numerical work concerning a planar metamaterial absorber, which composed of a crossed double nanorods on a dielectric layer with a gold substrate. Based on the resonance in the crossed nanorods and the similar-Bloch-wave resonance, the planar metamaterial structure can achieve multiple peaks with high absorption and narrow band. There are two nearly perfect absorption peaks obtained at 905 nm and 1161 nm, of which absorptivity and the bandwidth are 99.97%, 99.99% and 18 nm, 19 nm respectively. This peculiar feature may envisage the possible application of the structure in solar photovoltaic industry, biosensor, optical switch and filter.
Research Progress of Effects on Nanomaterials on Pyrotechnic Properties
Authors: Qin Qi , Cui Xiaoping
Published: September 2021

Nanomaterials have been widely concerned by researchersin in recent years, because of its unique physical and chemical properties, which play an irreplaceable role in improving the performance and safety of pyrotechnics. In this paper, in the light of the effects of nanomaterials on pyrotechnic properties such as metal nanoparticles, metal oxide nanoparticles, composite nanoparticles, carbon-based nanomaterials, the latest research progress and current research situation are reviewed from two aspects including thermal decomposition temperature and decomposition heat, and the function mechanism was analysed. The future research directions are expected.
Component distribution of nano-carbon materials assisted by Time of Flight-Secondary Ion Mass Spectrometer
Authors: Dong Ying , Xu Fan , Li Yan , Song Tinglu , Tan Guoqiang
Published: September 2021

Currently, there exist various materials surface analysis and characterization techniques, but it is difficult to measure their component distribution, in particular from a three-dimensional prospect. In this paper, the component distribution of nano-carbon materials in 2D and 3D views were both characterized via Time of Flight-Secondary Ion Mass Spectrometer (TOF-SIMS). The results indicate that TOF-SIMS could provide comprehensive information about component distribution, which is expected to be developed as an advanced technology in material analysis and characterization to the research community.
Template Preparation and Experimental Study on Superhydrophilic-Superoleophobic Nano-structures Surfaces Based on Titanium Mesh Membrane
Authors: Jian Wang , Xuezeng Zhao , lei Chen , Mingying Chen
Published: September 2021

With the development of industrial process, the crude oil leakage of industrial oil wastewater is increasingly serious. The development of efficient and environmentally friendly separation mesh membrane technology is the best way to solve the water pollution problem. With the rapid development of micro-nanotechnology, the wetting change caused by surface structure (micro-nano scale) that can solve the problem of fabrication for oil-water separation mesh. If the liquid contact angle at the surface is less than 10°, the surfaces are called superhydrophilic surfaces. Meanwhile, the liquid contact angle is greater than 150°, the surfaces are called superhydrophobic surface. Surface with superhydrophilic/superhydrophobic is also known as special wetting surfaces. The special wetting surface is fabricated by coating / spraying. The process is simple and easy to operate. By constructing the multi-stage surface roughness and reducing the surface energy, the titanium mesh with different orders are used as the base. the mesh membrane with special superhydrophilic-superoleophobic properties is constructed. Comparing the influence of titanium mesh with different molybdenum numbers (mesh size) on hydrophilic/ hydrophobicity, the mechanism of the macroscopic size of the pore spacing substrate on the special surface wetting is analyzed. The preparation of ultra-hydrophobic multi-stage surface roughness titanium mesh is realized. The experimental analysis of oil and water separation effect is carried out. For the preparation of high-efficiency oil-water separation mesh film that can be used in industrial production. The oil and water separation mesh membrane was prepared by the titanium mesh substrate to achieve effective oil and water separation.
Experimental study on the evolution law of residual stress in the fatigue process of inductively quenched 42CrMo steel
Authors: Zhang Yongfang , Kang Sifan , Dong Lihong , Wang Haidou , Di Yuelan , Li Shaofan
Published: September 2021

In the process of remanufacturing a crankshaft with a history of service, it is found that the residual stress of the crankshaft will relax during operation. Therefore, the relaxation of residual stress must be considered in the study of crankshaft remanufacturing. X-ray diffraction is used to measure the initial and final residual stresses after each loading cycle, and the changes in the microstructure of the material after induction quenching were also measured by scanning electron microscopy. The results show that the maximum residual compressive stress appears inside the sample, and its size decreases with increasing depth. The relaxation of residual stress on the surface of the sample with hardened layer can be roughly divided into three stages: rapid relaxation, stable relaxation, and instantaneous release of the final fracture residual stress. An empirical model is proposed to estimate the residual stress relaxation, considering the depth of the hardened layer and the external load during the fatigue process to predict the relaxation law of the residual stress.
Effects of simulated in-situ electrokinetic remediation on physicochemical properties and phosphorus migration of sediments
Authors: Wang Huapeng , Li Jincheng , Wang Xiaoxiao , Lu Zuxian , Wei Chunman , Luo Xuejing , Zhong Yijian
Published: September 2021

The effect of simulated in-situ electrokinetic remediation (EKR) on phosphorus release from contaminated sediments was investigated. The effects of different anode materials (iron, aluminum, graphite and stainless steel) on the physicochemical properties and phosphorus migration were compared. The results showed that aluminum anode had the best inhibition effect on phosphorus release from sediments, and the highest inhibition rate of phosphorus release was 78.20% compared with non EKR, but the sustainability was poor, and the performance of iron anode is generally stable. The phosphorus in the sediments generally shows the migration trend from cathode to anode. After EKR, the Oxidation-Reduction Potential (ORP) of the sediment decreased with the increase of normalized distance from anode. The anaerobic environment of the sediment on iron anode was the most serious, and the lowest was -616mV. The ORP of the sediment from the anode area to the middle area of other electrodes was effectively improved. The pH of the sediment increases gradually from anode to cathode, and is characterized by acidification in the anode area and alkalization in the cathode area. Iron and stainless steel electrodes have more acidic areas, showing better electrolysis efficiency.
Thermodynamic modeling of continuous flow liquid helium thermostat
Authors: Yan Rundong , Jiang Ziyun
Published: September 2021

Since the discovery of cryogenic superconductivity, liquid helium-based cryogenic superconductivity has been successfully applied in many disciplines. And continuous flow cry-ostats have great importance for the efficient and stable operation of the entire cryogenic system, which can provide a cryogenic working environment for large scale cryogenic applications. In this paper, a thermodynamic model of the liquid helium thermostat is developed based on the principle of continuous flow helium cryostat and the thermodynamic processes between liquid helium and gas helium, using mass conservation, energy conservation and pressure-volume-temperature relationships. The research work can provide theoretical guidance for the stability analysis of continuous flow cryostats, and also has practical value in large-scale cryogenic applications.
Dynamic analysis of flame propagation velocity at the initial stage of gasoline-air explosion in a tube with an open end
Authors: Zhang Peili , Xiao Jun , Wu Jingsi
Published: September 2021

Gasoline-air explosion in confined space is a process involving complex fluid mechanics and explosion mechanics. The flame behavior of gasoline-air explosion in a tube with an open end is mainly discussed in this paper. Firstly, on the basis of experimental observation and theoretical analysis, the axial position of the flame front, the flame velocity and the duration of the spherical flame are deduced and calculated. Then, the validity of the theoretical analysis is verified by comparing the theoretical calculation with the experimental data. The results show that the flame velocity is about 2.29m/s at the initial stage of gasoline-air explosion in the tube. The duration of the spherical flame is about 11.7ms. The conclusions of this paper can not only provide valuable data reference for combustible gas explosion safety engineering, fire protection design and evaluation, but also lay a foundation for further research on the flame behavior of gasoline-air explosion in the tubes with an open end.
Fluid Dynamics Research for Nozzle Flow with the Computational Fluid Dynamics
Authors: Kong Xiangyuan , Wang Dongchi
Published: September 2021

Nozzle is a kind of fluid equipment with a wide range of applications. Research on the internal flow of the nozzle is very important for improving the performance of the nozzle or improving the design of the nozzle. In this study, the flow conditions in the convergent-divergent nozzle, as well as the convergent or divergent nozzles are solved and explored by numerical simulations based on Euler equations. It is found that the fluid Mach number is affected by many factors. With the increase of the density, temperature, and pressure, the fluid Mach number will decrease. In the study of the nozzle shape, a discovery for the nozzle flow rate is that the change of the physical parameters of the fluid will fluctuate due to the increase of the cross-sectional area, and specifically it will slow down this change.
Optical dynamic measurement of welding deformation
Authors: Wang Gaofeng , Yang Fengping , Zhang Liang , Yuan Yingtao , Su Xin , Guo Xiang
Published: September 2021

This paper presents an optical measurement method of welding deformation. Through the use of target detection, camera calibration, 3D metric reconstruction, we obtain the precision 3D location of targets, which are deformed in welding processing. With the data, the deformation of the workpiece in welding processing can be performed, and the manufacture and design level of welding can be improved.
Research on Numerical Simulation of Soft Soil Foundation Reinforcement during the Process of Under-Crossing Subway Shield Tunnel
Authors: Wenjie Gao , Yu Yang , Lingzhi Xi
Published: September 2021

The disturbance of shield construction in coastal soft soil area poses a threat to the use and even safety of adjacent municipal transportation facilities. In order to study the influence of under-crossing shield construction on municipal transportation facilities in soft soil area, taking a practical project as an example, the author adopted numerical analysis method to conduct a comparative study of the influence of foundation reinforcement on under-crossing shield open-cut tunnels and bridges. The results show that for open-cut tunnels and bridges, foundation reinforcement can greatly reduce the deformation and internal force of the structure after under-crossing shield. At the same time, different reinforcement depths and methods will also lead to different results. The full reinforcement of 2 meters is obviously deeper than that of 3 meters, and strip-shaped reinforcement with 6-meter spacing has worse performance. Determining a reasonable reinforcement depth is of great significance for saving costs.
Investigation of the Influence of Laval Nozzle Throat Width via Euler-based Flow Simulation
Authors: Lu Yu’ang
Published: September 2021

The nozzle is a kind of widely used fluid equipment. It is very important to study its internal flow for improving nozzle performance or improving nozzle design. In this paper, the numerical simulation method based on the Euler equation is used to solve the flow in the nozzle. Euler equations are solved by an explicit finite difference method, including discretization, pre-estimation and correction steps. Boundary treatment for the subsonic inlet and supersonic outlet are discussed. The flow characteristics inside a Laval nozzle are analysed based on the numerical results. The influence of Laval nozzle throat width on the nozzle flow is investigated by comparing three nozzles. It is observed that the dimensionless pressure, temperature, and density of the three nozzles have similar trends. While the maximum Mach number at the outlet decreases with the increase of the throat width. In short, the throat width should be decreased if a larger outlet speed of the flow is needed.
Seismic Performance Analysis on a High-rise Hidden Frame-brace Structure
Authors: Yan Zhou , Hong-gang Lei
Published: September 2021

The building No.1 project located in the district of Jinjian Yingxiyuan at the city of Taiyuan is the first high-rise steel structure building in Shanxi Province by using hidden frame-brace system with the special-shaped wide concrete-filled steel tubular (WCFT) columns. In this paper, elastic analysis and pushover analysis of the new building are carried out by using the finite element software MIDAS/Gen, which is based on the theory of equivalent sectional flexural stiffness. And the results show that the various parameters under the action of frequent earthquake and rare earthquake meet requirements of the code, the failure mechanism of the structure is reasonable, and the seismic performance is good. Finally, the hidden danger and the key problems about the new structure system are put forward.
Research on Evaporative Cooling of Liquid in Container
Authors: He Ziting
Published: September 2021

Cooling is a common phenomenon in daily life. Among different means of cooling, evaporative cooling through the evaporation of liquids is a prominent method, for it removes large quantities of heat. Our prompt is aimed at evaluating the impacts of different parameters on the speed of evaporative cooling. We evaluate the degree of impact by the means of experiment and simulation of experiments with finite element simulation software COMSOL, using containers of different shapes, different wind speeds, and controlling the existence of evaporation. Research shows that the speed of evaporative cooling is mainly determined by the difference in the amount of evaporation, followed by the geometric shape category of the upper surface of the container. Simply changing the proportion of the upper surface of the container does not pose a large impact on the speed of evaporative cooling due to the impact from turbulence around the container and the conductive heat transfer of the container itself. In the process of the research, the experiment and simulation results achieve a high degree of agreement, confirming the accuracy of the simulation.
Design Analysis and Experimental Research of Multi-Segment Linear Reflector
Authors: Fang Houlin , Zhang Liangyong , Li Pengyi , Zhang Fang , Liu Yunzhe , Tang Shiying , Zhang Dezhi
Published: September 2021

The parabolic reflector provides one of the common sound wave convergence methods in acoustic engineering. To reduce the difficulty of fabricating large-size reflectors and improve the convergence effect, this paper proposes a multi-segment linear reflector design method. Through the normal vibration radiation analysis of the flextensional transducer shell, the reflector interface reflection was optimized, the reflection effect was improved and the reflector size was reduced. The transmission theory was used to analyze the impact of different material parameters and sound wave frequency on the reflector transmission coefficient, and the gain effect of the multi-segment linear reflector was further tested. The research results show that the reflector has a significant gain effect in the test frequency band of 20∼100Hz, and the gain at 70Hz I reaches the maximum of 11.2dB.
Nozzle Flow Simulation by Small Disturbance Approximation and Euler Method
Authors: Cheng Fanrui , Xu Yang , Zhou Wenbo
Published: September 2021

The nozzle is a kind of equipment with a wide range of usage in the aerospace industry, of which its performance is vital for rocket engines by changing the geometry of the inner wall of the pipe section to accelerate the airflow. There are two types of nozzles commonly used: one is a tapered nozzle, and the other is a Laval nozzle. To analyze the flow phenomenon in nozzle is vital before transferring prototype design into industrial production, whether by laboratory experiment or computational simulation. In this paper, two different numerical methods are adopted to simulate gas behavior inside a simplified nozzle with upper and bottom symmetrical bumps. The first is to solve one dimensional Euler equations, and the other is to solve a scalar variable named velocity potential with small disturbance equations (SDE). The solutions under various inlet Mach numbers are compared by analysing the velocity fields and Mach number contours obtained by these two approaches. Similarities and differences between the Euler method and the potential SDE method for subsonic flow and supersonic flow are the key emphases in this work. For either subsonic or supersonic flow, the Mach number distribution along the nozzle’s center line shows a consistent trend for both methods. In contrast, the values of maximum or minimum Mach number have corresponding differences. Moreover, by using potential SDE simulation, several types of shock waves are successfully captured. All results show that the incoming airflow decelerates at the leading edge of the nozzle then accelerates when passing through the bumps, and finally decelerates back to the speed of inlet flow. The difference is that flows with varied Mach numbers has distinct velocity distributions in the nozzle.
Using Cauchy theorem to compute complicated real integrals
Authors: Song Jiarui , Shi Zhanhua , Wang Haotao
Published: September 2021

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

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

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

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

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

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

The 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

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

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

It 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

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

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

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

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

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

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

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

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

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

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

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.
Utilizing Sawdust and Bottom Ash for Ecological Water Purifying Materials Produced
Authors: Wangrakdiskul U , Kankaew P
Published: September 2021

The expanding of industrial sectors has generated a huge number of wastes and further polluted the environment. Sawdust (SD) is considered as residue generating from the sawing, sanding, and milling process of the furniture industry. Likewise, bottom ash (BA) is the generated waste of palm oil mill production process. It is the residue of empty fruit bunch, palm fibre, and palm shell which is fuelled for boiling water in the palm oil plant. Reutilizing these wastes for developing porous purifying water is the objective of this study. Sediment soil and brown glass have been exploited for facilitating plasticity mixtures and reducing firing temperature. Rectangular specimens are moulded by uniaxial pressing at 70 bars. Firing temperature are set up at 950 and 1050 °C. The water filtrated by tested samples is examined and compared with TIS 257-2549 standard, i.e., pH value, turbidity, total dissolved solids. The results express that combination of 40% sawdust, 10% bottom ash, 50% sediment soil, and 40% brown glass fired at 1050° has the potential to be water purifier.
Prediction of Groundwater Level in The Shallow Aquifer Using Artificial Neural Network Approach
Authors: Ardana P D H , Redana I W , Yekti M I , Simpen I N
Published: September 2021

In these regions, groundwater is often the most significant source of water. Groundwater level estimation accuracy is a vital component of efficient water supply management. In this paper, an artificial neural network (ANN) with gradient descent with momentum and adaptive learning rate backpropagation algorithm for groundwater level forecasting applications is proposed. The ANN model used an 8-5-3-1 and 8-10-5-1 network architecture with the input parameter of the form such as precipitation, evaporation, atmospheric pressure, wind, humidity, long exposure to the sun and temperature simultaneously and a relatively short length of groundwater level data recorded from January 2017 to December 2019 at two observation wells in the North Denpasar, Bali, Indonesia. The study’s findings show that ANN models can predict groundwater levels. It is suggested that more research be conducted on this proposed process, which can then be used to help establish and incorporate more efficient and long-term groundwater management strategies.