bluuebunny/crossref_metadata_2025_split huggingface dataset:
Absorption Mechanism and Optimization of a Subwavelength Acoustic Absorber
Authors: Zhao Honggang , Wang Yang , Zheng Qiquan , Cao Junhui , Wen Jihong 
Published: March 2021

Abstract
A subwavelength acoustic absorber based on parallel coupled Helmholtz resonators is designed to extend the absorption band, where the lateral space is used and verified to reduce the overall thickness. Both theoretical analysis and finite element method are used to demonstrate the low frequency absorption performance. The ratio of absorber thickness to resonant wavelength acquires only 1.87%. It has found that the side location of perforation can move the absorption peak to lower frequency range. The absorption mechanism is investigated by analysing reflection coefficient in the complex frequency plane. The energy dissipation modes underlying absorption performance are further revealed by the viscous energy dissipation patterns. Finally, the absorber is optimized by a DE algorithm to extend the absorption band below 500Hz. The present design offers us an acoustic absorber with excellent stiffness and strength for low-frequency absorption.
Research on the Influencing Factors of FDM 3D Printing Accuracy
Authors: Zhou Changxiu , Han Tiantian 
Published: March 2021

Abstract
Printing accuracy is a general issue of FDM 3D Printing, take rectangular pieces made of PLA as an example, The effects of bottom/top thickness, filling density and placement position on the dimensional accuracy of printed pieces are studied. The results show that the influence of each factor on the dimensional accuracy of the workpiece has a directional difference.
Research on the Seismic Performance of Highly Durable Concrete Structures with Corrosion-resistant Reinforcing Steel Materials
Authors: Gao Ran 
Published: March 2021

Abstract
The combination of high durability concrete and GFRP reinforcement for infrastructure construction in the South China Sea can meet its durability requirements under high temperature, high humidity, high salt spray and high radiation environment. Due to the frequent seismic activities in the South China Sea, it is imperative to study the bearing capacity and seismic performance of GFRP reinforced high-durability concrete components and structures. The authors first analyzed the load-bearing performance of GFRP reinforced highly durable concrete beams and established the correction formula for its load-bearing capacity calculation based on the research results. Then the seismic performance of the GFRP reinforced high durability concrete structural members is studied. The seismic damage of the new structure and components is studied by analyzing the hysteresis curve, skeleton curve, stiffness degradation and other parameters. The time course curves and inter-layer displacement angles of GFRP reinforced high durable concrete structure are studied by adjusting the reinforcement type and concrete type, and finally the seismic performance of GFRP reinforced high durable concrete structure is obtained.
On the Natures of Thermally Induced Ultrasonic Emission from Nanofilm
Authors: Hu Hanping , Zhang Kai , Wang Dongdong 
Published: March 2021

Abstract
Thermo-acoustic (TA) ultrasound has lots of advantages over traditional electric-acoustic ultrasound. In this work, by using a full-field formulas derived for acoustic field of TA emission from arbitrary source based on a thermally-mechanically coupled model, the basic natures of TA emission from nanofilm are studied via carbon nanotube (CNT) film. It is found that the TA sound pressure level (SPL) is fluctuated in near field and attenuated in far field, the SPL fluctuation in near field results from the interference of TA waves emitted from every element of film, which directly leads to the existence of, in point of technique, the most important nature of TA wave--flat frequency response at certain condition, and in far field, all the sound-emitting films can be regarded as point sources. These researches are significant for understanding TA wave and developing a variety of TA devices.
Discussion on the Teaching of “Engineering Materials” with Philosophy Thoughts
Authors: Liu Yan , Qu Yanpeng , Song Qinghua , Chen Songying 
Published: March 2021

Abstract
The college students in engineering can improve their professional level and comprehensive ability through learning the knowledge with philosophical ideas. In the teaching practice on the course of engineering materials, the authors constructed the contents including the ideological and political factors, and linked the philosophy thoughts with the professional education. The main results are as follows. We understand the similarities of engineering materials and life connotation, and clarify the internal relation and interaction mechanism between materials and objective environment through explaining the environmental theory; We know that we should find out the the principal contradiction during the engineering materials selection and life path selection through the contradiction theory; We understand the influence of various factors on the change of material performances and the influence of creative tools on the development of disciplines through the things correlation theory;We recognize that we need to sum up the historical experiences and learn the failure analysis methods to reduce the probability of disaster accidents through the philosophy methodology. Some relevant teaching cases are introduced in this paper.
Study on the Coupling Association between Human and House under the Influence of the Evaluation Index of Urban Residents’ Behavior
Authors: Gao Chenglin , Wang Yaying 
Published: March 2021

Abstract
The interaction mechanism between people and houses in urban residential space is explained by the coupling relationship in the system of housing science, The mathematical model of the human house coupling association is derived by using the coupling relationship to explain the interaction mechanism of the people’s house in the urban residential space. The mutual coordination system of the user, space and objective under the relationship of building and living behavior. The results show that: The residential space and residential behavior in Changping District of Beijing are entering a period of high-level coupled and coordinated development. Among them, the residential cultural indicators and their subsystems show positive feedback on the coupling relationship between residential behavior and spatial correlation. In the living space, moral education is the core that affects human behavior and spatial coupling. The sustainable role of the creation of the space environment, coupled to the indoor ecological environment and the outdoor natural environment; The coupling protocol of man and residence has dynamic and procedural properties, which rely on the behavior communication mode of the internal stage of the space to establish the spatial system of systematic variability.
Study on the Preparation of AlN-Modified High Thermal Conductive Activated Carbon Based on Rice Huck Ash Residue
Authors: Feng Anwen , Qiao Xiaokang , Qin Wu , Sun Huahai , Han Bing , Zeng Zongming , Wang Xiaoqiang 
Published: March 2021

Abstract
Preparation of activated carbon from biomass ash residue can effectively treat solid waste and improve the economics of the biomass power generation industry. However, the low thermal conductivity of activated carbon (AC) cannot make it widely used. A strategy was reported herein modify the activated carbon by AlN increase its thermal conductivity. Effects of reaction temperature, nitriding time, and nitrogen flow rate on the formation AlN and summarized the optimal process of AlN modified activated carbon. The result showed that the optimal preparation process is to inject nitrogen at a rate of 300 ml/min, under the condition of 1550°C, nitriding reaction for 50 min. The thermal conductivity of AlN-modified activated carbon prepared by this process is twice that of unmodified activated carbon.
Construction and Evaluation of Urban Sponge Road Traffic System Structure
Authors: Mao Chengyuan , Yang Shengde , Wang Qin , Xu Wenjiao , Li Peiran , Zhang Yongliang 
Published: March 2021

Abstract
The imbalance of traffic resources is one of the important reasons that restrict the healthy development of the urban traffic system. Based on the concept of “sponge city”, this paper puts forward a kind of road traffic system, which can explore the flexible space of transportation infrastructure. The Fuzzy Analytic Hierarchy Process is established to comprehensively evaluate the system performance, deeply explore the flexible space of urban transportation facilities, and improve the performance of the urban transportation system. The sponge-type road traffic system evaluation model proposed in this paper can provide a reference for other regions to tap the flexible space of regional traffic infrastructure resources.
Forward Simulation Study on the Emission Characteristics of Volatile Organic Compounds in Cars
Authors: Tong Liping , Xu Shujie , Wang Lei , Liu Wei , Liu Xuefeng 
Published: March 2021

Abstract
Volatile organic compounds (VOC), represented by formaldehyde and benzene, are highly carcinogenic and teratogenic, and can easily cause dizziness, nausea, vomiting and other illnesses. Their emission characteristics have a significant risk to the physical and mental health of passengers. The forward simulation of the emission characteristics of VOC in cars has become one of the important technical challenges for the automotive industry. In order to solve this problem, the emission and adsorption characteristics of VOC from interior parts of a car were investigated through a multi-interior coexistence experimental system. Based on this, a VOC emission prediction model was proposed in combination with the mass conservation law of VOC in the car and Henry’s law of VOC, and validated by engineering amplification for 22 pieces of interior co-existence simulated final assembly experiments, illustrating that the relative standard deviations of the model for VOC in the car were 30.0% (benzene), 50.0% (toluene), -9.8% (ethylbenzene), 10.0% (xylene), -23.5% (formaldehyde), and -28.9% (acetaldehyde), respectively, with good prediction effect, which are able to greatly meet engineering needs.
Crack Propagation and Predication on 2024 Aluminum Alloy under Combination Action of Friction and Fatigue
Authors: Yan Yutao , Jiang Cheng , Li Yang , Wu Xin , Zhang Zhao 
Published: March 2021

Abstract
The crack propagation of 2024 aluminum alloy under the combination action of non-lubricated sliding friction and fatigue was investigated by numerical simulation analysis and experimental methods. The variation regulation of stress intensity factors (SIFs) KI and KII, and the fatigue crack propagation under different initial crack length, tension and contact pressure was obtained. Based on numerical analysis, experiment research and Paris formula, the predication model of fatigue crack propagation rate was established. The results show that the crack is closed owing to friction force when the upper specimen slides toward the crack, while is torn as sliding away. When the upper specimen moves in the near crack zone, there is relative motion between the crack faces caused by contact pressure. The crack appears slip-open effect. In according to numerical analysis and experimental results, the crack propagation is I-II composite crack forms. The comprehensive influence on I-II composite fatigue crack propagation from large to small is tension, contact pressure and initial crack length. The predication model is verified to reasonable and effective by the new test investigation.
Simulation Research on the Braking Characteristics between Tires of the 3-Module Virtual Track Train
Authors: Zuo Jianyong , Diao Pengfei , Zhou Chunmei , Wang Xueping , Dong Liwei 
Published: March 2021

Abstract
The virtual rail train is a new type of urban rail transportation, which integrates some of the characteristics of buses, trams and light rail trains. In order to study its braking stability, the paper appeared from the perspective of vehicle dynamics, studying the braking force allocation strategy of the train under different working conditions. It is proposed to calculate the articulation force of the train from the motion parameters of the train, and analyze the dynamic change of the tire vertical load. The lateral force is prioritized to ensure that the train turns stably and avoiding tire slip. After that, the remaining braking force is used to maximize the utilization of braking force. The results show that this method of braking force allocation between tires can ensure that the tires are not locked, while ensuring the braking strength.
Research on Load Identification of Articulated Connector
Authors: Wang Zhongxiang , Zhu Ning , Yin Yi , He Maosheng , Zhang Qiang 
Published: March 2021

Abstract
With the further development of the piggyback transportation technology, the number of external loads, the action form and the effect of the articulated connector, which is a key component of the piggyback, are becoming more and more important references for strength design. Due to the complex and irregular structure of the articulated connector, it is particularly important to accurately identify the external load on the articulated connector structure during actual driving. Through the establishment of an eight-unit piggyback dynamic model, the longitudinal, lateral and vertical loads of the articulated connector under the excitation of the American five-level spectrum orbit were analyzed, and the identification schemes of the longitudinal, lateral and vertical loads of the articulated connector are proposed. It shows that each load identification scheme can identify the corresponding load more accurately.
Research on the Device of Measuring the Centre of a Weight
Authors: Zhong Ruilin , Wang Jian , Lee Sungjun 
Published: March 2021

Abstract
In order to correct the influence on precision mass measurement caused by the difference between centres of the test weight and the reference weight, the centre of the weight need to be measured, and a device is developed to locate the centre of the weight which includes a balance, a bridge and a supporting pole. In this paper, the detailed force analysis of this device is studied, and the detailed information on designing and selecting each part of the device is given.
Evolution and invariants of free-particle moments
Authors: Andrews Mark 
Published: March 2021

Abstract
Moments are expectation values of products of powers of position and momentum, taken over quantum states (or averages over a set of classical particles). For free particles, the evolution in the quantum case is closely related to that of a set of classical particles. Here we consider the evolution of symmetrized moments for free particles in one dimension, first examining the geometric properties of the evolution for moments up to the fourth order, as determined by their extrema and inflections. These properties are specified by combinations of the moments that are invariant in that they remain constant under free evolution. An inequality constrains the fourth-order moments and shows that some geometric types of evolution are possible for a quantum particle but not possible classically, and some examples are examined. Explicit expressions are found for the moments of any order in terms of their initial values, for the invariant combinations, and for the moments in terms of these invariants.
Statistical evaluation of the competitiveness of agriculture in the regions
Authors: Romantseva Yu N , Kolomeeva E S 
Published: March 2021

Abstract
In the research work, the authors propose an approach to a comprehensive evaluation of agriculture competitiveness in the context of the regions of the Russian Federation based on the construction of a hierarchical multidimensional model. Current state of agriculture, its competitiveness, system of indicators of competitiveness of the agrarian sector, based on competitive advantages are assessed, choice of the most important indicators that formed the basis for regions division into three clusters differing in terms of agriculture functioning is justified. The analysis of clusters made it possible to identify directions for further development of groups of regions to achieve growth in agricultural production in accordance with the Forecast of socio-economic development of the Russian Federation for the period up to 2036 and the Strategy of spatial development of the Russian Federation for the period up to 2025.
Effect of secondary bacterial metabolites from permafrost on photosynthetic activity of potato (Solanum tuberosum L.) in vitro culture
Authors: Renev N O , Subbotin A M , Narushko M V , Malchevskiy V A 
Published: March 2021

Abstract
The influence of secondary metabolites of bacteria from perennially frozen rocks on the activity of photosynthesis processes in potato leaves cultivated in vitro has been studied. Early meristemous potato plants of Zhukovsky variety were used as an object of research. The concentration of photosynthetic pigments of chlorophylls a, b and carotenoids was determined by spectrophotometry. Calculation of concentrations of chlorophylls a, b and carotenoids by Wellburn formula. It was found that when potato microplants are grown together in the Murashige-Skoog nutrient medium with metabolites of bacteria of Bacillus cereus 9-08-CH9 and Achromobacter spanius 10-50TS2 strains, introduced at the moment of drawing in a dose of 250 pl, under conditions of sufficient and optimal nutrition the process of photosynthesis is stimulated. First of all: by activating the light-gathering ability of the plant, by increasing the synthesis of chlorophyll b (on day 20), as well as increasing the resistance of plants to adverse environmental factors, through the synthesis of carotenoids (on day 30). The obtained results can be used for creation of biopreparations on the basis of microbial metabolites in order to increase efficiency of microclonal reproduction technology of potatoes.
Application of active exoskeletons with touch sensing, electric drives, energy recuperators and gravity compensators in agricultural technologies
Authors: Borisov A V , Borisova V L , Konchina L V , Kulikova M G , Maslova K S 
Published: March 2021

Abstract
The article describes a model of a digital human-machine system, in the form of a three-dimensional model of an active exoskeleton with five links of variable length, developed for possible use in agriculture. The difference between the proposed model of an active exoskeleton and the existing ones is that links are used that can change their length under the action of applied loads, and energy recuperators are built into these links. In each joint of the links between each other there are gravity compensators. These design solutions can reduce the load on the electric drives of the exoskeleton and increase the battery life of the device, which is important when used in agriculture. As an interface between a person and an exoskeleton, touch sensing will be used. The principle of operation is that the signals from the touch sensors will be sent to the control module of the exoskeleton, amplified and implemented by electric drives in accordance with the movement of each link of the human endoskeleton with minimal delay. Each link of the exoskeleton consists of two sections of constant length, having a mass, and one weightless section between them, changing its length. The links are connected to each other by a combination of joints. A set of differential equations is written in the form of a system describing the exoskeleton dynamics. This system was written in a generalizing matrix-vector form. Much attention is paid to the possibility of real application of the proposed model of the active exoskeleton in agriculture and the positive results arising from its practical use.
Evaluation of the effect of micronutrient fertilizers based on chelates on grape and wine quality characteristics
Authors: Cherviak S , Anikina N , Ermikhina M , Aleinikova N , Didenko P 
Published: March 2021

Abstract
Mineral nutrition plays an important role in the processes of growth and development of the grape vine. Our studies show that using microfertilizers based on chelates during the growing season contributes to an increase in the bunch weight by 3.9-18.2 g and in the grape yield by 5.4-18.9%. Experimental grape samples are characterized by a higher content of titratable acids (by 0.8-1.8 g/l) and anthocyanins in a berry (by 12-39%), the proportion of extractable anthocyanins (by 3-8%) and a low content of seed tannins (by 2-3 times) compared to the control. In the prepared wines, the content of the total dry extract and phenolic substances exceeded the control values by 1.3-6.1 g/l and 13-27%, respectively. Experimental systems of treatment had a positive effect on the quality characteristics of wines: red color, varietal aroma of berry direction, fresh and fuller palate compared to the control variant, which was reflected in the tasting assessment (5-7 points higher than the control).
Agrobiological methods of increase in germinating capacity of seeds of perennial legume grasses in the Middle Preduralie
Authors: Zubarev Y N , Zabolotnova M V 
Published: March 2021

Abstract
The article presents the results of laboratory research of swelling rate of non-traditional for the region perennial crops: Gelega orientalis, Poterium polygamum in comparison with traditional Medicago varia Mart. Investigation of watering and swelling process was carried out by gravimetric method. Positive effect of scarification on the rate of water consumption of Galega orientalis and Medicago varia Mart is confirmed: swelling rate of Galega orientalis increased from 0.14 1/h up to 1.09 l/h, Medicago varia Mart – from 0.24 l/h up to 1.85 l/h, which is seven times more than the swelling rate of non-scarified seeds. The swelling rate of scarified seeds of Poterium polygamum conversely decreased from 1.69 l/h to 0.74 l/h. Laboratory seed germination of Galega orientalis and Medicago varia Mart with seed scarification and soaking up to 60% of water level increased threefold relative to the control variant without scarification and twofold to the control variant with scarification. Negative effect on biometric parameters of Galega orientalis and Medicago varia Mart seedlings was noted when seeds were soaked up to 100% of water level. Laboratory germination of Poterium polygamum in all experimental variants was equal to 96%. However, parameters of seedlings were different regarding experimental factors, thus biometric parameters of seedlings increased with the raise of water level in non-scarified seeds of Poterium polygamum and decreased in scarified ones.