bluuebunny/crossref_metadata_2025 huggingface dataset:
A novel reversible thermometric organic material for power transmission line detection application
Authors: Cheng Li , Ziwen Shang , Minzhen Wang , Li Liu , Guangxin Zhang , Liyin Zhao , Hongxia Ni , Xiao Zhang , Jian Zhang , Dongliang Qiao
Published: September 2021

Due to the inaccuracy of the existing fault detection method caused by the overheating of the equipment of the long-spanning overhead transmission line, this paper creatively proposes a detection method of the reversible thermochromic organic thin film material HCBCC which can be deposited on the equipment or hardware of the transmission line based on the electron transfer mechanism. In this method, the film material made with five components in accordance with the optimal ratio was named HCBCC film, and the coloration performance of the material was determined by UV-Vis absorption spectroscopy, temperature variable infrared spectroscopy, differential scanning calorimetry and other characterization methods. Then, its durability was verified through environmental tests such as high and low temperature, rain and snow, wind and sand, and aging. HCBCC material has the advantages of easy observation, fast color rendering and wide temperature range in the temperature indicator, which not only greatly reduces the intensity of inspection work for staff and can find fault points in time, but also saves a lot of time for the emergency repair of power equipment and provides guarantee for the safe and stable operation of power grid.
The impact of the use of new environmentally friendly materials on the management of construction projects: Taking straw fiber materials as an example
Authors: Chen Lin , Yang Mingyu
Published: September 2021

With the rapid development of the construction industry, the social economy has experienced a golden period of development, and the construction industry has experienced an unprecedented high rate of growth. Because of its rapid development, the construction industry has contributed to the development of the world economy, but at the same time, there are other problems, such as the construction of houses, roads, and tunnels, which consume much non-renewable energy and release many harmful gases, leading to the greenhouse effect and the rise in global temperature. As non-renewable energy sources continue to be consumed, society’s resources are decreasing, and the earth’s ecological environment is gradually deteriorating. Therefore, in the future of the construction industry, not only its materials in terms of strength, durability, and other aspects of higher requirements, but also on the environment-friendly construction materials more attention, so the project cost control and management of materials play a more critical role. This paper takes straw fiber material as an example through the extraction and preparation of straw fiber and then analyses its material in quality, cost, and construction of the three aspects of the content, derived from the material in the quality, cost, and construction of the three sides of the impact, through the rational and effective use of new environmentally friendly building materials, thus to drive the world’s new green building materials in the development of scientific and technological innovation, while promoting the world’s low-carbon economy in the development of important the role of guidance.
Analysis on Concrete Construction Technology in Civil Engineering Construction
Authors: Guo Yuzhen
Published: September 2021

An important structural material in civil engineering construction is concrete. Concrete is widely used in various building structures. Concrete construction technology directly determines the construction quality of the concrete structure itself, which plays a very important role in the stability of the building structure. This paper mainly summarizes the current construction situation of concrete, and deeply analyzes some problems and technical points in the construction process, which is of great significance to improving the construction quality of concrete and optimizing the construction management of concrete. On this basis, this paper expounds the maintenance ideas of concrete pouring from the aspects of concrete mold removal, later repair and concrete maintenance operation, so as to provide a reference for the technical improvement of concrete construction.
Structural analysis of a school building with viscous dampers applied
Authors: Wu Xiangxiang , Zhou Dawei , Huang Tianrong
Published: September 2021

Viscous damper, as a type of energy-dissipating device, is applied in the 3-story school building. To investigate the function of viscous dampers, seismic nonlinear analysis is performed on the FE model with viscous dampers simulated in. The analysis is done for both minor earthquake and severe earthquake. The analysis results show that the viscous dampers start to dissipate energy in minor earthquake input and dissipate more energy in severe earthquake. Therefore, application of viscous dampers significantly reduce the seismic response of the building and effectively protect the structure building from severe damage or collapse.
Construction Key Techniques of Upper Cross-beam for Main Tower of Super-Kilometer Span Rail-cum-Road Suspension Bridge
Authors: Wen-xuan FU
Published: September 2021

As the span of the suspension bridge increases, the height of the main tower and the force on the tower increase. The beam profile volume and pouring weight become larger, which increases the risk of high-altitude construction of the main tower and the upper cross beam. The main bridge of Wufengshan Changjiang River Bridge of Lianzhen Railway is the first rail-cum-road suspension bridge in China. The main span reaches 1092m and the total height of the tower is 191.5m. Taking the engineering practice of the upper cross beam of the main tower of Wufengshan Changjiang River Bridge of Lianzhen Railway as an example, this paper introduces the construction difficulties of the upper cross beam of the main tower, the selection of the upper cross beam construction support, the structural characteristics of the support and the construction process. The upper cross beam is constructed asynchronously with the tower. From the bottom of the upper cross beam to the top of the lower cross beam is 121.5m. The upper cross beam was poured in six times with a total concrete volume of 1918m3. The method of small trusses with bracket and floor steel pipe support is used for construction. The finite element analysis software is used to calculate the super-high support of the upper cross beam, and the support strength, rigidity and stability meet the requirements of the specification. At present, the bridge has been partially put into use, which verifies the rationality of the design and construction of the beam support on the main tower. It has strong reference and guiding value.
Comparison for Solid Concrete-filled Circular Steel Tubes Load-carrying Capacities in Frame Structures Basing on Chinese codes
Authors: Yu-tong Duan , Hong-gang Lei
Published: September 2021

Solid steel tubular concrete members have excellent axial compression capacity. In terms of the calculation method of their axial compression bearing capacity, the current ten domestic standards all provide specific provisions. On the basis of main structure provisions such as diameter-thickness ratio and confinement factor, the formula differences in axial-force compression capability of domestic and international standards are compared and analyzed. First, the difference value of bearing capacities reach up to 62.79% according to current standards when diameter-thickness ratio range from 4 to 30. Second, concrete-filled steel tube members with diameter-thickness ratio greater than 20 and diameter less than 200, the current specifications cannot calculate the axial compressive bearing capacity.
Influence of Process Parameters of Unidirectional Glass Fiber Fabric on Resin Infiltration Rate
Authors: Qianjin Xia , MingYang Hao , HongSheng Zhang , Hai Zhong
Published: September 2021

The tensile and compressive strength, torsional strength, and fatigue strength of wind turbine blades are closely related to the infusion defects during the manufacturing process of blade girders. Inadequate understanding of the resin infiltration process of the glass fiber fabric is one of key factors leading to the infusion defects. This article mainly studies the influence of fabric weft TEX, weft angle, stitch length, and stitch tension on the resin infiltration rate through experiments. The results show that the resin infiltration rate in the 90° direction of fabric increases as weft TEX and weft angle increase and that the infiltration rate in the thickness direction increases when stitch length and stitch tension increase.
Mix Design Recycled Aggregate Pervious Concrete and the Influence on Pavement Property
Authors: Yuxi Du , Feng Tang , Xin Zhou , Zhiqian Lv
Published: September 2021

This paper prepared recycled aggregate pervious concrete by replacing natural aggregate with 100% volume of waste concrete. We carried out experiments to study the influences of strength grade and target porosity of waste recycled aggregate concrete on the recycled one’s compressive strength and permeability coefficient. Then, the optimal proportion meeting the requirements of pervious concrete pavement is obtained, which is expected to be applied to the pavement with low strength requirement and water permeability. The test results of the compressive strength and permeability coefficient of 28-day test cubes show that, considering both the compressive strength and permeability, the best proportion is as follows: the strength grade of recycled aggregate is C20 + C30, the mix proportion of aggregate is 50%, the target porosity is 15%, the water-cement ratio is 0.3, the recycled aggregate is composed of 50% recycled aggregate with a particle size of 4.75-9.5 mm and 50% that of 9.5-19 mm, and the optimal mix proportion of recycled aggregate pervious concrete (kg/m3) is: m (recycled aggregate): m (cement): m (water) = 1357.04:564.94:169.88. The compressive strength and the permeability coefficient of recycled aggregate pervious concrete based on this mix proportion are 25.07 Mpa and 6.23 mm/s, respectively, which are in line with the provisions of Technical Specification for Application of Recycled Aggregate Pervious Concrete (CJJ/T 253-2016) and can be used for pavement. The study results can provide a reference for the promotion and application of recycled aggregate pervious concrete in the pavement.
Preparation and Performance of A Novel Type of Concrete Air Entraining Agent
Authors: Wang Yongmei , Ng Serina , Ni Tao , Song Xin , Feng Ke
Published: September 2021

This article uses 1,4-dibromobutane, hexadecyl primary amine, sodium 3-chloro-2-hydroxypropionate, formaldehyde and formic acid as raw materials to synthesize a new type of concrete air entraining agent of (1,4)-bis(cetylmethyl hydroxy-propionic acid quaternary ammonium salt) butane through the reaction of ammonia alkylation and quaternization. The article characterizes the molecular architecture of the product, the surface activity of the aqueous solution, the bubble properties, the air entraining and air stabilizing properties of the fresh concrete, and the pore structure of the concrete after hardening. The research results show that the synthesized (1,4)-bis(cetylmethyl hydroxy-propionic acid quaternary ammonium salt) butane has good surface activity in aqueous solution, and its critical micelle concentration (cmc) is 5.3×10-4 mmol/L, γ
cmc
is 28.86 mN/m; (1,4)-bis(cetylmethyl hydroxy-propionic acid quaternary ammonium salt) butane has better air-entraining performance and bubble stability in aqueous solution and concrete than SDS and AOS air entraining agents. The average chord length and spacing coefficient of bubbles in hardened concrete are smaller than that of SDS and AOS air entraining agent, giving rise to a better overall pore structure of the concrete. Compared with SDS and AOS, the concrete mixed with (1,4)-bis(cetylmethyl hydroxy-propionic acid quaternary ammonium salt) butane air entraining agent shows better mechanical property and durability.
Effect of Air Entraining Agents on The Air Void Structure of Concrete
Authors: Song Xin , Ng Serina , Ni Tao , Wang Yong Mei , Ke Feng
Published: September 2021

Four different air entraining agents are selected. The air entraining effect and their foaming stabilities in cement pore solution; the impact on air entrainment in fresh concrete; and the variations in air voids and their structures in hardened concrete are compared and studied. The results show that the development in porosity of the hardened concrete mixed with different air entraining agents is consistent with the air entrainment in fresh concretes within the first hour, but deviated from the foaming stability of the air entraining agents in cement pore solutions. Carboxylic based air entraining agents generate calcium soap, whereby such moiety can effectively encapsulate air bubbles. While the stability is insignificant in cement pore solution, the impact is obvious in concrete. When employed alone, the air entraining agent failed to improve both air entrainment of fresh concrete and final concrete structure. Instead, a combination of air entraining agents is found to induce a synergetic effect, effectively enabling both the air-entraining performance and the development of an enhanced porous structure of the hardened concrete.
Molecular Dynamics Simulation of the Mechanical Behavior of Mixed-Layer Clay upon Hydration
Authors: Yang Yu , Xu Guoyuan
Published: September 2021

A proper understanding of the the mechanical behavior of clay minerals is of crucial importance in earth sciences, soil mechanics, and geotechnical engineering. Although more than seventy percent of all clays are of mixed layer types, the vast majority of the previous studies are devoted to pure clays, which make the hydraulic and mechanical properties of the widespread mixed-layer clay (MLC) and its role in soils are little understood, especially the most common illite-montmorillonite (I-M) mixed-layer clay (MLC). This research reports on a molecular dynamics (MD) study of the differences in mechanical behavior between I-M MLC containing mixed K+ and Na+ and Na-montmorillonite (Na-MMT). The variations of key components in stiffness matrix with hydration have been analyzed. It is found that the stiffness tensor of two types of clay could be split into two groups: the in-plane coefficients (C11, C12, C22, and C66) and the out-of-plane coefficients (C13, C23, C33, C44, and C55). Due to the different forms of the support force of the clay layered structure in the two directions, they exhibit significantly different hydration mechanisms. Moreover, the I-M MLC is more difficult to hydrate and swell due to the asymmetric I-M interlayer and the existence of K+, and its ability to resist deformation is stronger than Na-MMT. This work offers insight into the molecular mechanism for initial swelling and mechanical behavior in widespread MLC. This will help to decipher its specific role in soils and controlling clay swelling.
Experimental Study on Silt Liquefaction by Shaking Table Test
Authors: Luo Qiang
Published: September 2021

Based on the shaking table test, the liquefaction of silt under earthquake load and the earthquake damage after liquefaction are studied. The test results show that the lower silt is relatively dense, the pore pressure increases slowly, and the pore pressure ratio can not reach the initial liquefaction state. However, under the stronger earthquake action, the dense silt may also produce liquefaction, which indicates that the increase of pore water pressure has a great relationship with the compactness and earthquake intensity under the earthquake load. Because the permeability coefficient of silt is relatively low, the increase and dissipation of pore pressure are relatively slow. After the earthquake, he pore pressure of silt continues to rise, and the liquefaction will be further aggravated.
Study on Corrosion Characteristics of Grounding Materials in High Corrosion Area
Authors: Huang Mingxiang , Zhang Jianxun
Published: September 2021

Due to the differences in the causes of corrosion, the soil corrosion characteristics in coastal mountains and coastal areas may be quite different. As a result, there are differences in the corrosion causes, corrosion status and service life of the grounding grids of the transmission line towers built in coastal areas. Based on the difference in apparent resistivity of the soil under the transmission line towers in a coastal area with high corrosion, this paper selects 12 soil samples for physical and chemical analysis. The analysis results show that there are two typical soils of acid and weak alkaline in the transmission line erection area, which are highly corrosive but with different corrosion mechanisms. Then the soil liquids of two typical soils were extracted, and the polarization curve test of carbon steel and galvanized steel, which are commonly used in the grounding grid of poles and towers, was carried out for 7 consecutive days, and the corrosion laws of carbon steel and galvanized steel were obtained. The results show that the corrosiveness of acidic soil is much greater than that of weakly alkaline soil. The corrosion rates of carbon steel and galvanized steel in acidic soil are 3.7 times and 5.2 times that of weakly alkaline soil, respectively. In addition, using the extracted soil liquid, a 30-day accelerated corrosion experiment was performed on carbon steel and galvanized steel, and an empirical formula for the change of corrosion weight with time was obtained. Combined with the surface morphology characteristics and corrosion rate after corrosion, this paper analyzed corrosion mechanism of two grounding materials. The research results of this paper provide a reference for the selection and application of grounding materials.
Low frequency electromagnetic casting of large size ZA21 magnesium alloy slab ingot
Authors: Niu Yanxia , Shi Yan , Le Qichi , Wang Yixuan , Ren Shuai , Wang Na
Published: September 2021

Surface quality and microstructure of ZA21 magnesium slab ingots by the direct-chill (DC) casting and low frequency electromagnetic direct chill casting (LFEC)were Deeply and systematically investigated. The surface quality of alloy ingot by LFEC casting is better than that without electromagnetic casting. The crack of ingot was avoided by applying electromagnetic field. The microstructure of ingot without electromagnetic field is coarse columnar grains, on the contrary, the microstructure of ingot by applying electromagnetic field is uniform equiaxed grains. The electromagnetic field can accelerate the flow of the melt and make the dendrite arm break to form equiaxed grains. In addition, the flow of the melt reduces the stress concentration in the solidification process, so that the crack can be avoided.
Preparation of a Novel UHMWPE Lithium Battery Separator by Electrospraying Method
Authors: Liu Taiqi , Zhao Yunteng , Han Ziye , Wu Jincheng , Zhao Rong , An Xue , Zhao Xiaomin , Li Yan , Zhang Lei
Published: September 2021

In this paper, an ultra high molecular weight polyethylene (UHMWPE) lithium ion battery composite separator was successfully prepared via the electrospraying technique. First, the optimal electrospraying parameters of Polyvinylidene fluoride (PVDF), mass fraction of PVDF 3wt% and electrospraying voltage 21kV, were successfully determined by adjusting the effect of voltage and concentration of PVDF solution. Then the composite separator was prepared by electrospraying PVDF particles on the UHMWPE film. Finally the porosity rate, thermal stability and charge and discharge properties of the separator were analyzed. The analytical results show that the porosity rate of the composite separator is increased from 46.5% to 73.1%, and the heat shrinkage of the separator in the longitudinal is reduced from 2.6% to 1.3%. The first specific discharge capacity of the composite separator increases by 5.8%, and the separator has a good cycle stability after 50 cycles.
Preparation of A2B7-type La-Mg-Ni Hydrogen Storage Alloy and Its Catalytic Oxidation Performance for BH4
-
Authors: Xinyu Liu , Xiao Tian , Mingyue Ji , Lu Tian
Published: September 2021

The La-Mg-Ni hydrogen storage alloys with A2B7/AB5 double phase were successfully prepared by vacuum melting combined with ball milling. The phase structure, electrochemical properties and the catalytic oxidation properties for BH4- of the (Mm1-xMgx)Ni2.485Co0.525Mn0.28Al0.21 (x=0.1-0.5 )alloys were investigated by XRD and electrochemical measurements. The results showed that (Mm1-xMgx)Ni2.485Co0.525Mn0.28Al0.21 alloys are composed of LaNi5 phase and (La, Mg)2Ni7 phase. Among the studied alloys, the electrochemical properties of the alloy with x=0.3 is the best, and the electrochemical properties of the alloy with x=0.3 is significantly better than that of the AB5-type hydrogen storage alloy, which is mainly due to the formation of (La, Mg)2Ni7 phase in the alloy. At the same time, the alloy with x=0.3 also shows a better catalytic oxidation effect on BH4-, which is also better than that of the AB5- type hydrogen storage alloy. The catalysis of (Mm1-xMgx)Ni2.485Co0.525Mn0.28Al0.21 alloy catalyst is related to its electrochemical performance. The catalysis of hydrogen storage alloys may have a positive correlation with its own electrochemical performance.
Sample trapped charge induced signals in tapping-mode atom ic force microscopy
Authors: Wang Yu , Zhou Chuxiang , Xu Jie
Published: September 2021

AFM (Atomic force microscope) has been used to measure the surface topography and electrochemical properties of the sample by the interaction between the tip on the cantilever and the sample. However, when there is a charge in the sample, an induced charge will be generated inside the tip, which will generate a new attractive force between the tip and the sample and reduce the amplitude of the tip. We found that the average amplitude of the tip decreased by about 1 nm in tapping mode AFM. As the amplitude decreasing, AFM keeps the amplitude constant by adjusting z0 with negative feedback in tapping mode. So, the average charge density will affect the measurement of surface topography.
One-step hydrothermal method for preparing carbon dots and its determination of lead (II)
Authors: Shen Yongling , Wu Hongyi , Li Jian , Liu Guohong , Xiao Yanhua , Dai Zhifei , Zhen Hongling
Published: September 2021

As a new type of carbon nanomaterials, carbon dots have attracted great interest due to their non-toxic, low preparation cost and unique photoluminescence properties. They have been widely studied and shown great potential in many fields. Here, nitrogen doped fluorescent carbon dots were prepared by one-step hydrothermal method using Epiphyllum leaves as raw materials. Ultraviolet-visible absorption spectrometer and fluorescence spectrometer were used to study the optical properties of carbon dots. The elemental composition and morphology of the surface of carbon dots were analyzed by transmission electron microscope, Fourier transform infrared spectroscopy and X-ray photoelectron spectrometer. The results show that the prepared carbon dots are uniformly dispersed in the aqueous solution, emit blue fluorescence, and the average particle size is 4.2 nm. The carbon dots have good light stability and strong anti-photobleaching ability. Continuous spectral scanning of the carbon dots can keep the fluorescence intensity basically unchanged within 30 minutes. In the concentration of 0∼f molL-1NaCl solution, the strength is not affected by the ionic strength. In the pH range of 4∼ 8, the fluorescence intensity of carbon dots is basically stable. The heavy metal ion pb2+ has a quenching effect on the fluorescence of carbon dots, and has a good linear relationship in the range of 0.5*200 μm. Therefore, a simple and green method for pb2+ has been developed.
The development of fluid dynamics and its future application
Authors: Ni Heyang , Yao Shengtao , Zhou Zhaoliang
Published: September 2021

The development of fluid dynamics is essential to many related topics in mechanics. With the emerging high technology, people have begun to discover more functions suitable for fluid mechanics. This article mainly summarizes the following two aspects. One is to review the historical development of fluid mechanics on the time axis, and to summarize the important achievements of fluid mechanics in recent years. The second is to summarize the practical applications of fluid mechanics in aviation, engineering application, shipbuilding and daily life. It points out in detail the shortcomings and deficiencies in the development of computational fluid mechanics so far, and points out the direction for the future development of computational fluid mechanics.
The influence of aerodynamic on stability performance of amphibian on rough water
Authors: Huang Miao , Wu Bin , Li Chenghua , Tang BinBin
Published: September 2021

In allusion to the aerodynamic lift difference between tank test model and full scale plane, a simulation method of lift to tank test model is put forward, and conduct model test on rough water at the model status with boundary layer control technology (BLC) and without BLC, and then we study the influence of aerodynamic lift on trim and heaving characteristic of the test model systematically, the results turn out to be that: the influence of aerodynamic on trim is affected by test velocity, at relatively low speed, this difference can be ignored, but at higher speed, the maximum trim value difference lies the range of 2%∼7%, and the wave length corresponding to the maximum value decreases. The influence of aerodynamic on heaving is affected by wave length, at relative shorter wave length, the heaving value decreases a little between the model with BLC and without BLC, this difference lies about 10%, but this difference increases to 15%∼40% at higher wave length.
Two Simulation Methods of Brownian Motion
Authors: Liu Zhisong , Jia Yueke
Published: September 2021

Einstein-Smoluchowski’s theory and Langevin’s theory are two main theories to describe Brownian motion. The Einstein-Smoluchowski theory regards Brownian motion as random walking of Brownian particles, while the Langevin theory establishes a random differential equation describing the motion of Brownian particles. Both theories involve random numbers, i.e., only the statistical results can be discussed. Based on the above theories, this paper presents the corresponding simulations, which verifies the statistical conclusions as well as compares their similarities, differences, and applicable conditions. These results offer a guideline for further studies on Brownian motion.
Study on optimal design of a new type of beam-column assembled rigid joint
Authors: Chen Hong , Luo Wei , Zhao Fengbing , Tang Jiao , Geng Limei
Published: September 2021

With the progress of engineering technology, steel structure has become the mainstream structural form of construction engineering, and beam column composite structure is the most commonly used connection form in steel structure buildings. In order to improve the design and construction performance of beam-column joint, a new type of beam-column assembled rigid joint is proposed and its parameter optimization is analysed based on equal strength design method and finite element software. The results show that the new beam-column assembled rigid joint has excellent performance for ductility and energy-dissipating capacity and the joints and splice plates can both meet strength requirements. The number of bolts and the length of cantilever beam have great influence on the ultimate bearing capacity and ductility of the joint. The new type of beam-column assembled joint is easy to construct and has good mechanical properties, and its ductility and elastoplasticity are better than those of ordinary joints without splicing.
Contact Problem with Friction of Rolls
Authors: Zhang Ping , Lu Xiao-jun
Published: September 2021

Based on the engineering background of the roller of steel rolling, researching the contact problem of two long parallel cylinders and considering the infection of friction. Gained the stress expressions when the vertical load and the friction act on the rolls separately, then according with superposition theorem of elastic mechanics, gained the stress expressions with the contact pressure and the friction force combined action.
Study on interfacial connecting properties of small molecule intervention repairable epoxy composites
Authors: Zhao Tianyu , Bai Heshan , Lei Zhenkun , Bai Ruixiang
Published: September 2021

The interfacial bonding method and mechanical properties of new repairable epoxy and its composites were studied. Ethylene glycol was used to connect the resin interface. The effects of temperature, time and resin content on the strength of interface bonding were systematically studied, and the optimal bonding scheme was determined. The results show that this connection method has significant advantages, and the tensile strength reaches 73% of the intact resin. Furthermore, the reparable resin matrix fiber-reinforced composite was prepared, and this method was successfully extended to the composite connecting. The interfacial shear strength of the fiber composites reached 21.88 MPa by single lap test, which has a good application prospect.
A study on the mechanism of morphing features of tuna median fins during C-turns
Authors: Xiaohu Li , Zhen Su
Published: September 2021

The median fins of tuna can morph in position and shape to enhance their hydrodynamic performance. Based on the C-turn kinematic equations and the self-propulsion swimming numerical model, the hydrodynamics of the median fins in different morphing forms (erected and depressed forms) are analyzed under the condition of three-degree of freedom (3DoF) self-propulsion, and then the assisted-turning mechanism of the median fins is clarified. The results show that the erected median fins have higher hydrodynamic forces, which can not only increase the yaw speed, but also reduce the turning radius to a certain extent.
The Gutman Index of the Unicyclic Graphs with pendent edges
Authors: Feng Mengmeng , Yu Xiangran , Zhang Jing , Duan Wei
Published: September 2021

The graph-parameters mainly studies vertex degree and distance between unordered vertices. There are many graph-parameters, and this paper mainly focuses on the Gutman index. For the sake of discussion, this paper puts forward the concept of “contribution” based on the relationship between Gutman index of graph and vertex-Gutman index. On this basis, we discussed the Gutman index of unicyclic graph with pendent edges in odd and even parts, and gave the corresponding extremal graphs, which lays a foundation for the study of the Gutman index of other cycle graphs.
A hybrid method for fast and robust topology optimization
Authors: Liao Jingping , Huang Gao , Chen Xuechao , Yu Zhangguo , Huang Qiang , Meng Fei
Published: September 2021

To accelerate the convergence rate and obtain robust optimal results with clear profiles of structural topologies, this paper proposes a hybrid multi-population genetic algorithm (MPGA) and bi-directional evolutionary structural optimization (BESO) method for structural topology optimization. Each element in the design domain is treated as an individual and the elemental sensitivity is taken as the fitness function of one individual. Based on these treatments, MPGA operators, including crossover, mutation, migration and selection, are modified to adapt to compliance minimization problems. Additionally, some key parameters are controlled to guarantee a convergent solution and to solve the structural unconnectivity problem. A case is used to verify the effectiveness and efficiency of the proposed method. The numerical results show that the proposed method is efficient, and compared with the BESO method and combined simple genetic algorithm and BESO method, the proposed method provides a powerful ability in searching for better robust solutions and improving convergence speed.
Research on numerical solution of one-sided monotonic function dichotomy
Authors: Liu Tianshi , Dong Yangmei
Published: September 2021

Aiming at the numerical solution problem of given interval dichotomy, the concept of one-sided monotonic function is proposed, and the unique existence of the solution is proved when the two ends of the function take different signs. Therefore, this significantly relaxes the discrimination conditions and effectively expands the numerical solution range of the dichotomy method. On this basis, it is proved that the one-sided monotonic function is a monotonic function in a relatively small interval containing the zero point. The introduction of the concept of one-sided monotonic function provides a theoretical basis for further expanding the application range of the dichotomy numerical solution, and has certain theoretical and practical significance for dealing with scientific and engineering problems as well as related numerical calculation problems.
Algebraic and Topological Structures of Complex Numbers
Authors: Lv Quanjin , Peng Xinghao , Wu Yuqing , Zhang Jiaying
Published: September 2021

Complex numbers play a fundamental role in every branch of mathematics. First, we review the definition of the complex numbers, discuss their arithmetic operation properties and give proof of the Lagrange identity. At last, we take the investigation of topological notations of the complex plane
Bridge strain denoising method based on variational mode decomposition
Authors: Yang Ming , Cheng Hanjian , Lu Zheyuan
Published: September 2021

In the construction and maintenance of bridge, it is very important to measure the strain of bridge accurately. However, the bridge strain measured in practical engineering is often mixed with a lot of signal noise, how to effectively remove the signal noise is a problem. Variational mode decomposition (VMD) is a denoising algorithm proposed in recent years, which has been applied in some engineering fields. Based on the vehicle bridge coupling theory, the strain of the bridge is obtained by numerical simulation, and the Gauss white noise is added to the strain to simulate the actual engineering situation. Based on VMD theory, a new bridge strain denoising method is proposed, and some key parameters are analyzed. The results of numerical simulation show that the denoising algorithm is effective. For example, when the signal-to-noise ratio of bridge strain data is 10dB, it can be increased to 21.67dB after using VMD denoising algorithm.
Monotonicity Formula On Cigar Soliton
Authors: Wan Ruizhe
Published: September 2021

In this paper, we prove a monotonicity formula on cigar soliton. Using the monotonicity, we obtain a three-ball type theorem. There might be some people who have proved the three-ball theorem on Cigar Soliton before, but we use a new method. We add a weight function in the norm of u. By doing so, we make the calculation process much easier because when using integral by part, the term that integrates at the surface of ball would disappear as the weight function we add would be zero.
Simulation of nozzle flow based on Euler equations
Authors: Chen Kaipeng , Liu Haoze , Tang Yinghan
Published: September 2021

The nozzle is a widely used device in daily life, such as water fountains to rocket engines. It is important to find out the influence of the position of the nozzle throat for the application or the design of the nozzle. To that end, the finite difference method was employed to solve the 1D Euler equations to obtain the flow inside the nozzle. To implement the method, an in-house python code was developed. The relationship among the velocity, pressure and density in the convergent-divergent nozzle flow was found. It is observed that: the velocity rose quickly along with the nozzle and reached the top before a rapid decrease; pressure remained constant initially, which eventually began to drop; density dropped steadily and had a turning point. Moreover, the influence of the nozzle throat position is investigated thoroughly. It is observed that the position of the nozzle throat influences the velocities at the nozzle exit. The faster the flow reaches the throat, the higher the velocity or Mach number at the exit boundary.
A Mechanical Model for Radial Inertial Impact Switch
Authors: Ma Bing , Wu Peng , Wang Sen , Wang Zhen , Xu Pengzhao
Published: September 2021

The traditional inertial impact switch based on experience design often appears in the problem of early closure within the threshold. To solve this problem, a new method of inertial switch design is presented in this paper. Firstly, the force analysis of inertia switch is carried out and a mechanical model is established. Through the model, it is concluded that the closing threshold of inertia switch is related to the spring resistance, the mass and center of mass of contact pole, the spring radius of contact pole and the horizontal projection of the minimum distance between the spring and the reference point. After that, the mechanical model is verified by simulation, and the correctness of the mechanical model is proved. The experimental results show that the proposed model can effectively solve the problem of premature closing of the inertial switch within the threshold and improve the pass rate of the product.
Analysis of the Mainstream Interpretation of Quantum Physics
Authors: Zhang Yitian
Published: September 2021

Quantum physics is changed in an unexpected way. Scientists believe that the study of quantum physics will play an important role in future technology. Therefore, it is meaningful to study quantum physics. The aim of this paper is to provide an initial explanation of the quantum world through the classical single particle double-slit interpretation experiment, and to answer a few questions about the experiment using mainstream quantum mechanical interpretations, such as the Copenhagen interpretation and the Many-Worlds interpretation. The superposition state, which is the core of the Copenhagen interpretation, is then introduced. The Einstein-Podolsky-Rosen paradox and locality are also introduced, and the relationship between the latter and special relativity is analyzed. The author also discusses whether non-locality leads to retrocausality. Finally, the author discusses the relationship between multi-world interpretation and Schrodinger’s cat, but this may raise some philosophical questions. However, realist and hidden variable interpretation are also consistent as long as locality is abandoned.
Design of a Long-stroke Low-frequency Sound Device
Authors: Fang Houlin , Zhang Fang , Li Ao , Zhang Liangyong , Li Pengyi , Liu Yunzhe , Zhang Dezhi
Published: September 2021

In order to improve the radiation performance of low-frequency sound device, a design method for a long-stroke low-frequency sound device is proposed, which mainly involves the design of the drive structure and radiation structure and the drive structure is designed with an electric long stoke. The flat plate and conical structures of piston plate of radiation structure are compared, and a long-stroke radiation structure with a low-damping guide support motion pair uniformly distributed in the circumferential direction is proposed. The numerical simulation results show that, with six straight-line bearings circumferentially and uniformly distributed, the displacement and stress distribution of piston plate are better than those of piston plate with three straight-line bearings installed in the same manner. The sound device is further tested in the experiment, and it is found that the vibration displacement amplitude at the center of piston plate is 3.9 mm (20 Hz), and the maximum sound pressure level of 40 Hz is found at the location 10 m from the center of sound device along the axial direction, reaching 105.3 dB.
Principles, Detections and Applications of Cosmological Gravitational Waves
Authors: Hanhao Chen , Sirou Zhao , Suqing Xie
Published: September 2021

Contemporarily, the gravitational wave has played an important role in the field of astronomy. A systematic review of the gravitational wave is presented in this paper. Primarily, the principle of gravitational waves is introduced in both Newton and Einstein’s concept of gravity. Besides, we deduced the solution of Einstein’s field equation. Moreover, we described the detection of gravitational waves with the mechanisms of the two gravitational wave detectors LIGO and Virgo Finally, the applications of gravitational waves are discussed in detecting black hole mergers, neutron star mergers, gamma-ray burst, and core-Collapse Supernova explosion. The gravitational wave could contribute to more scientific findings in the future and solve more mysteries of the Universe.
The Chaos Theory and its Application
Authors: Su Feier
Published: September 2021

Chaos Theory is not only one of the most active branches of the dynamical system, but also one of the most important topics of the nonlinear scientific field. The main purpose of this thesis is to introduce and illustrate the basic concepts, characteristics, and various applications of Chaos Theory. Chaos Theory is widely applied in physics, biology, and economics fields etc., so the thesis will also exhibit interdisciplinary research on Chaos Theory. The conclusion is that the most important refinement of Chaos Theory is its sensitivity to initial values, and subtle changes will affect the final shape and state of the entire structure.
Sporadic cell death in macroscale 3D tumor grafts with high drug resistance by activating cell-ECM interactions
Authors: Lee Sang Woo , Park Se Eun , Jeong Gi Seok
Published: September 2021

In the tumor microenvironment (TME), the extracellular matrix (ECM) provides a dynamic structure for cell adhesion and cancer cell motility, such as migration and invasion, as well as remodeling. Matrix metalloproteinases (MMPs) promote cancer cell motility, which contributes to inducing drug resistance and thereby acquiring aggressive features. The drug resistance-induced 3D in vitro tumor model can be an effective model for therapeutic strategies for anticancer drugs targeting aggressive cancer cells. Here, we describe highly drug-resistant multicellular tumoroids (MCTs)-ECM tumor grafts under a macroscale dense 3D in vitro model through a combination of numerous MCTs and a collagen matrix. MCTs-ECM tumor grafts promote the high activity of MMP2 and MMP9 compared to general MCTs and induced cancer cell motility. Then, after the administration of anticancer drugs, the tumor grafts show increased drug resistance, with both the sporadic distribution of necrotic cells and the reduction of apoptotic portions, by activating cancer cell motility. MCTs-ECM tumor graft could be useful as a macroscale tumor graft model for inducing drug resistance by activating cancer cell motility and evaluating the efficacy of anticancer drugs targeting cancer with aggressive features.
Photoluminescence and excited states dynamics of Tm2+-doped CsCa(Cl/Br)3 and CsCa(Br/I)3 perovskites
Authors: Plokker M P , Biner D A , Dusoswa N , Dorenbos P , Krämer K W , Van Der Kolk E
Published: September 2021

In this study, we systematically vary the Cl/Br and Br/I ratios in CsCaX3:Tm2+ (X = Cl, Br, I) and hereby gradually shift the positions of the Tm2+ 4f125d1-levels as relative to the two 4f13 levels. At low temperatures up to five distinct Tm2+ 4f125d1→4f13 emissions and the 4f13→4f13 emission can be observed. As the temperature increases, most of the 4f125d1→4f13 emissions undergo quenching via multi-phonon relaxation (MPR) and at room temperature only the lowest energy 4f125d1→4f13 and the 4f13→4f13 emission remains. For all compositions a 4f13→4f13 risetime phenomenon is then observed whose duration matches the 4f125d1→4f13 decay time. It shows the feeding of the 4f13 state after 4f125d1 excitation. Surprisingly, the feeding time becomes longer from Cl→Br→I, while the related 4f125d1-4f13 energy gap becomes smaller. The temperature dependence of the 4f125d1→4f13 and 4f13→4f13 emission intensity shows a anticorrelation as earlier observed in other systems and confirms that the feeding process is thermally stimulated. However, the thermally stimulated activation energies that control the feeding process, increase from Cl→Br→I despite our observation that the 4f125d1-4f13 energy gap becomes smaller. An analysis reveals that the unexpected behaviour in risetime and activation energy, as a function of composition, cannot be explained by 4f125d1→4f13 feeding via interband crossing, but more likely via MPR where the electron–phonon coupling strength decreases from Cl→Br→I. No strong relation was found between composition and the quantum efficiency (QE) of the 4f13→4f13 emission, due to the presence of fluctuations that are likely caused by intrinsic differences in sample quality. Nevertheless, a 4f13→4f13 QE of up to 70% has been observed and the materials can therefore be used in luminescence solar concentrators.
Trajectories of depressive symptoms and subsequent cognitive decline in older adults: a pooled analysis of two longitudinal cohorts
Authors: Zhu Yidan , Li Chenglong , Xie Wuxiang , Zhong Baoliang , Wu Yangfeng , Blumenthal James A
Published: September 2021

Background

the course of depression is variable, but it is unknown how this variability over time affects long-term cognitive decline.

Objective

to examine the relationship of different trajectories of depressive symptoms on rates of subsequent cognitive decline in older adults.

Design

population-based cohort study.

Setting

communities in the USA and England.

Subjects

17,556 older adults from the Health and Retirement Study and the English Longitudinal Study of Ageing.

Methods

depressive symptoms were assessed using the Center for Epidemiologic Studies Depression Scale, and trajectories were calculated using group-based trajectory modelling. Global cognitive function and three cognitive domains of memory, executive function and temporal orientation were assessed for up to 18 years.

Results

five trajectories of depressive symptoms were identified. Compared with the ‘non-depressed’ trajectory, the ‘worsening depressive symptoms’ trajectory (pooled β = −0.016 standard deviation (SD)/year, 95% confidence interval (CI): −0.021 to −0.010), ‘persistent depressive symptoms’ trajectory (pooled β = −0.016 SD/year, 95% CI: −0.024 to −0.008), and ‘mild depressive symptoms’ trajectory (pooled β = −0.008 SD/year, 95% CI: −0.014 to −0.003) were associated with faster rates of cognitive decline, while no such association was found for the ‘improving depressive symptoms’ trajectory (pooled β = 0.001 SD/year, 95% CI: −0.010 to 0.012).

Conclusions

subthreshold depressive symptoms are associated with an increased rate of cognitive decline, while individuals who show improving depressive symptoms do not exhibit accelerated cognitive decline. These findings raise the possibility that maintaining depressive symptoms as low as possible and ignoring the clinical threshold, might mitigate cognitive decline in older adults.
World History and the Tasman Sea
Authors: Bashford Alison
Published: September 2021

Tracking and analyzing connection and mobility are now conventional in oceanic and world historiography and in many Indigenous historiographies. This article offers a counterargument and counterinstance. On both sides of the Tasman Sea lie human histories of almost incommensurably different temporal orders, separate for several centuries and suddenly connected in 1770, when Polynesians and Aboriginal people met. The Tasman Sea turns out to be one of the more fascinating fault lines for world historians who seek to fold ancient and modern, so-called prehistory and history, together into new periodizations of deep time and shallow time. It suggests the need seriously to consider a Tasman Divide as much as a connected Tasman World. This article recasts James Cook’s crossing of the Tasman Sea in 1770 less as a significant first contact between Englishmen and Indigenous Australians on that coast and more as a meeting of three peoples who occupied radically different temporalities: (1) the Polynesian Tupaia, (2) the Englishman James Cook, and (3) Aboriginal people whose names we do not know.