bluuebunny/crossref_metadata_2025 huggingface dataset:
Research on urban density model and resilient development model under the guidance of carbon emission
Authors: Shen Shifang , Yu Yiting
Published: June 2021

In this study, we used time series data from 2001 to 2018 to quantify the relationship between urban density and carbon emissions in Shanghai. The regression equation is used to analyze the relationship between urban carbon emissions and urban density in the past ten years. According to national policies and the calculation of peak carbon emissions, the urban density under the peak carbon emissions is derived as the appropriate urban density. This paper puts forward the concept of urban density index, calculates the density index of Shanghai and analyzes it.
Research on the Influence of Students Gender on Students Examination Scores——Based on Logistic regression model
Authors: Hu Sen , Hu Yue
Published: June 2021

When students enter the middle school stage, students of different genders will show different advantages in different subjects. In order to explore the influence of students’ gender characteristics on students’ specialties, this paper uses logit regression to conduct an empirical analysis of students’ performance. This article uses student achievement data, which uses different subject scores as explanatory variables and student gender as the explanatory variable. Finally, it is found that student gender factors will have a significant impact on student performance in different subjects. Based on the analysis of student performance data, this article believes that schools should formulate different education programs according to the gender factors of students, so as to teach students in accordance with their aptitude.
Research on Input-output Efficiency of Junior High School-A Case Study of DEA-OLS Model
Authors: Gao Jiacheng , Liu Yue
Published: June 2021

Junior high school education has a strong influence on students’ first major decision in life, which leads to a large proportion of their investment in educational resources, so it is necessary to evaluate their comprehensive efficiency. Based on the questionnaire data of principals from 2014 school year to 2015 school year of China Education Tracking Survey, this paper uses DEA-OLS model to calculate and analyze the input-output efficiency of junior high schools, and finds that the input-output efficiency of junior high schools is low on average. Compared with computer students, the efficiency of teacher-student ratio has a significant negative impact. According to this, it is proposed that junior high schools should make their own adjustment plans in combination with teachers’ teaching quality and the amount of teachers’ resources, as well as the curriculum arrangement of students’ computer skills training and the amount of computer resources.
Underestimated marine stratocumulus cloud feedback associated with overly active deep convection in models
Authors: Hirota N , Ogura T , Shiogama H , Caldwell P , Watanabe M , Kamae Y , Suzuki K
Published: June 2021

Cloud feedback remains the largest source of uncertainty in equilibrium climate sensitivity (ECS). Many studies have attempted to narrow uncertainties in cloud feedback and ECS by proposing observable metrics with high skill at predicting future climate, referred to as emergent constraints. These constraints are often associated with clouds, convection, and circulation, and are interrelated. However, physical explanations for these connections remain unclear. Here, we propose a new mechanism relating convection and clouds across multiple climate models. Some models show overly active deep convection on daily timescales in the subtropical low cloud regions, which contributes to weaker subsidence inversion and smaller amounts of low-level clouds. Such models predict smaller shortwave (SW) cloud feedback. Using precipitation frequency in these regions as an emergent constraint, encapsulating this mechanism, models with lower SW cloud feedback (<0.50 W m−2 °C−1) are found to exhibit erroneously frequent convection. Our results suggest that further improvements in understanding and better modeling of cloud and convective systems are necessary for accurate climate predictions.
Zooming in on Arctic urban nature: green and blue space in Nadym, Siberia
Authors: Fedorov R , Kuklina V , Sizov O , Soromotin A , Prihodko N , Pechkin A , Krasnenko A , Lobanov A , Esau I
Published: June 2021

Urban landscape combines built-up areas with strongly altered natural (green and blue) and other open spaces. Voluminous literature examines urban socio-environmental interactions in tropical and temperate cities, whereas high-latitude cities are rarely considered. Here, we create a historical perspective on urban green (vegetation) and blue (water) spaces in a sub-Arctic city of Nadym in Russia. Our study explores a novel way to combine quantitative information from satellite imagery and biometric studies with qualitative information from interviews with stakeholders and residents. Such a joint analysis helps to understand dynamics of the urban green and blue space as well as its value for society. Furthermore, we propose objective indicators reflecting societal values of spaces in connection with recreational and ecological services. By contrast to temperate city studies, we found that green space is less used in summer, but still highly valued, deep lakes are used and valued more than warmer shallow lakes, and winter white space do not shrink but enhance the urban public space. Satellite images reveal inevitable loss of green space to urban construction and its remediation by artificial plantings (almost by 30% at present), whereas less valued blue space decreased almost three-fold. Interviews reveal that shallow lakes have reduced recreational values due to ice bottom and algae bloom. High values are attributed to deep artificial lakes, which are more than ten times deeper than natural lakes and do not freeze throughout in winter. Our biometric studies show that trees in urban environment are significantly taller than in the corresponding undisturbed areas. Since majority of the Arctic cities are built using very similar planning ideas and technologies, our findings shall help objective appreciation of green and blue spaces in other settlements.
Cleaner air has contributed one-fifth of US maize and soybean yield gains since 1999
Authors: Lobell David B , Burney Jennifer A
Published: June 2021

Crop productivity is potentially affected by several air pollutants, although these are usually studied in isolation. A significant challenge to understanding the effects of multiple pollutants in many regions is the dearth of air quality data near agricultural fields. Here we empirically estimate the effect of four key pollutants (ozone (O3), particulate matter (PM), sulfur dioxide (SO2), and nitrogen dioxide (NO2)) on maize and soybean yields in the United States using a combination of administrative data and satellite-derived yield estimates. We identify clear negative effects of exposure to O3, PM, and SO2 in both crops, using yields measured in the vicinity of monitoring stations. We also show that while stations measuring NO2 are too sparse to reliably estimate a yield effect, the strong gradient of NO2 concentrations near power plants allows us to more precisely estimate NO2 effects using satellite measured yield gradients. The presence of some powerplants that turn on and others that shut down during the study period are particularly useful for attributing yield gradients to pollution. We estimate that total yield losses from these pollutants averaged roughly 5% for both maize and soybean over the past two decades. While all four pollutants have statistically significant effects, PM and NO2 appear more damaging to crops at current levels than O3 and SO2. Finally, we find that the significant improvement in air quality since 1999 has halved the impact of poor air quality on major crops and contributed to yield increases that represent roughly 20% of overall yield gains over that period.
Tropical rainfall monitoring with commercial microwave links in Sri Lanka
Authors: Overeem Aart , Leijnse Hidde , van Leth Thomas C , Bogerd Linda , Priebe Jan , Tricarico Daniele , Droste Arjan , Uijlenhoet Remko
Published: June 2021

Commercial microwave links (CMLs) from cellular telecommunication networks can provide a valuable ‘opportunistic’ source of high-resolution space-time rainfall information, complementing traditional in-situ measurement devices (rain gauges, disdrometers) and remote sensors (weather radars, satellites). Their greatest potential lies in areas with low gauge densities and lack of weather radars, often in developing countries with a subtropical or tropical climate and generally large spatial rainfall variability. Here, the open-source R package RAINLINK is employed to retrieve CML rainfall maps covering the majority of Sri Lanka for a 3.5 month period based on CML data from on average 1140 link paths. These are compared locally to hourly and daily rain gauge data, as well as to rainfall maps from the dual-frequency precipitation radar on board the global precipitation measurement core observatory satellite. The potential of CMLs for real-time tropical rainfall monitoring is demonstrated.
Construction and experimental study of Langmuir model for multi-molecular layer adsorption of porous materials
Authors: Jucheng Gao , Zhaohe Zhang , Chunhui Liu , Weiwei Zhang , Yingchun Wang
Published: June 2021

In this paper, a Langmuir isothermal adsorption model was developed based on the assumption of multi-molecular layer adsorption, and then adsorption experiments were carried out using coconut shell activated carbon samples as adsorbent. The results showed that multi-molecular layer Langmuir isothermal adsorption model is more widely used than the traditional single-molecular layer Langmuir adsorption model, and it is also more simple, more intuitive and more standardized than the BET adsorption equation based on the multi-molecular layer adsorption assumption, and its application is more convenient.
Experimental Study on the Characteristics of Acoustic Emission Source of Rock under Uniaxial Compression
Authors: Song Zhaoyang
Published: June 2021

One of the main research problems in acoustic emission (AE) monitoring technology is to identify the source of the acoustic emission. Processing the acoustic emission signal is the only way to solve this problem, and then to achieve the purpose of identifying the material destruction mode. Using acoustic emission monitoring technology, the acoustic emission of granite under uniaxial compression was monitored and analyzed, and the coupling characteristics between the acoustic emission signal parameters of granite under different loading rates were obtained. The results show that during the process of rock shear failure, the peak intensity of the rock, the peak value of the absolute energy of acoustic emission, the cumulative amount of acoustic emission and the loading rate showed a positive correlation. The correlation diagram of the AE ringing count and the duration shows a triangular distribution, and as the rock loading rate decreases, the angle of the triangle top angle of the correlation diagram increases. The distribution relationship between the absolute energy of AE and the duration can be fitted using a unary quadratic function, and as the loading rate decreases, the opening of the fitting curve gradually increases, and the width of the correlation graph gradually decreases. The correlation graph of absolute energy and amplitude of AE is linearly distributed, and as the loading rate decreases, the slope of the fitted line of absolute energy and amplitude of AE gradually decreases, and the width of the linear channel of the correlation graph decreases. It is found that there is a good regularity between the correlation graphs of different parameters of the acoustic emission of the rock during the uniaxial compression failure process, which is an effective method to identify the characteristics of the source of the acoustic emission. Therefore, establishing the correspondence between the characteristics of the AE source and the loading conditions will promote the development of acoustic emission technology in the monitoring of the stability of the surrounding rock of underground projects.
Construction optimization of PBA of Subway station tunnel excavation and its cross section in loess area
Authors: Chen Qingrui , Zheng Xuanrong , Yin Zhanbo , Shang Xuexuan , Lei Qi , Yang Kang , Qi Jiahui , Cheng Weikang
Published: June 2021

This paper takes the project of Hejiaying Station of Xi’an Subway Line 2 as the background for the study. The dynamic numerical simulation of the construction process of the station by the PBA method is carried out using the 3D finite element method. The changes of surface settlement, vault settlement, headroom convergence and structural stresses are studied up to the intersection of the guide tunnel and large section duct. The research results show that: the construction of the upper guide hole of the station has a small effect on the deformation and internal force of the initial support structure of the duct. The construction of the lower pilot hole will increase the deformation and internal force of the initial support structure of the duct, especially the construction of the lower 2 pilot holes and the lower 3 pilot holes will lead to a significant increase in the deformation and internal force of the initial support structure of the duct. Therefore, it is necessary to make a 10m reservation for the lower guide hole of the main line, and to grout the cross section of the lower guide hole to ensure the safe construction of the cross section.
Safety risk prediction of cantilever construction of sanduizi super large bridge on Jinshajiang River Based on basic Bayes model
Authors: Yang Yan , Wen Chao
Published: June 2021

In order to better control the safety risk of bridge construction, this paper takes the cantilever construction of sanduizi super large bridge on Jinshajiang River as an example, and establishes the safety risk prediction model by using Bayes principle. Firstly, it constructs the Bayes relationship model of construction environmental factors and cantilever construction key process risk factors and events, and then uses Bayes theory to analyze the probability of risk events in various cases. Finally, the overall safety risk of cantilever construction, the influence degree of various influencing factors on the overall safety risk and the most unfavorable risk combination are studied. Through the application of examples, the results show that on the basis of theoretical research, targeted safety control measures are taken, and the safety risk is effectively controlled.
The Analysis of Characteristic Coastal Landscape Design
Authors: Yu Hang , Qin Yang
Published: June 2021

With the development of social economy and the progress of science and technology, nowadays, coastal landscape design has attracted more and more attention from all walks of life. The focuses of paper are that how to combine natural conditions to create beautiful coastal space environment, solve coastal ecological problems, innovate coastal regional characteristics and show coastal culture. Through expounding the principles of coastal landscape design, analyzing the key points of coastal landscape design, and combining with the coastal design cases of Tianjin and Xiamen, this paper further studies the key points of coastal landscape design and characteristic expression channels, and guides and promotes the construction and development of coastal areas in the landscape field from a higher level.
Measurement and Comparison Study of Road Roughness Conditions by using Two Compact Road Profiler for Evaluating Ride Quality
Authors: Abulizi Nueraihemaitijiang , Wei Mao , Maimaiti Rehanguli , Tomiyama Kazuya
Published: June 2021

More recently, it is strongly required that road management involves a wide range of topics over the world and it must be considered from a perspective of customer-oriented levels of service and road administrators are requested to present a visual map of road network in terms of road network monitoring among others. To fulfill these requirements, firstly, this paper introduces new topics, which is related to two Compact Road Profiler (CRP) to monitor the road roughness conditions including localized distresses. In addition, we analyze road profile data considering two wheel paths by the survey vehicle, known as inner and outer wheel paths, and using a sophisticated driving simulator (DS) to evaluate ride quality conditions based on Power Spectrum Density (PSD) function to identify the sensitive range of ride quality. Finally, we calculate the Root Mean Square (R.M.S) and Crest Factor (CF) using vertical acceleration data of the passenger seat in DS. Consequently, it is shown that advanced evaluation of the ride quality under two wheel paths is performed. As regards standard for ride evaluation, ISO 2631 standard is adopted.
Design and Analysis of a Linear Conveying System
Authors: Liangfa Li
Published: June 2021

Based on the transportation demand of medium- and short-distance materials, this paper proposed a method to design and analyze a conveyor system, which has simple structure, low cost and flexible drive. A simplified system model was established and the design method of the system was introduced. Geometric equations, velocity and acceleration calculation formulas were obtained through mathematical analysis calculations. The simulation model was established through ADAMS, so as to obtain the kinematics law and verify the design accuracy. The organization and its design analysis process can provide references for the design of similar products.
Design of Tianjin Baimiao Passenger Station
Authors: Wang Ning
Published: June 2021

The purpose of this design is to carry on the reconstruction planning to the present Baimiao passenger station, in order to improve its passenger flow and service quality, improve the residents’ travel experience. In this paper, the passenger volume of Tianjin from 2010 to 2019 is taken as the research object, and the passenger volume of Baimiao Passenger Station is predicted by exponential smoothing method from 2021 to 2028. Then, the passenger volume of Baimiao Passenger Station is predicted according to the proportion of total passenger volume in Tianjin. Then make reasonable planning for Baimiao passenger station.. Finally, some constructive suggestions are put forward.
Route Optimization of AGVs with an Improved Fishbone Warehouse Layout
Authors: Wanying Zhu , Xiaoqing Wei , Ruofei Ma , lin Diao , Jianchen Zhang
Published: June 2021

AGV (Automated Guided Vehicles) as one of the most intelligent technologies is widely applied in the warehousing operations with a high speed development in the intelligent logistic fields. Automated material warehousing systems have proved that they would improve the effectiveness of material loading, unloading and handling company as well as reducing the labor cost and strengthening the working safety. AGV, as one part of the automated material warehousing systems, preforms powerful actions in the full chain of cargo handling in warehouse. Effective planning of AGV running route is the key for improving the efficiency of material loading and unloading. Based on this, this article aims to improve warehouse operation efficiency and control capabilities with an innovated fishbone layout warehouse design. Firstly, the improved fishbone warehouse layout is designed by an embedded central corridor compared to classical layout. Then, AGV route optimization model is proposed, which is transformed into secondary allocation model for getting a better and more optimal solution. Finally, the genetic algorithm is used to verify the feasibility of the proposed model. The results show that the proposed route optimization method for AGV can effectively reduce the distance among materials shelf and loading point according to the improved fishbone layout warehouse. Under the same circumstances, the reduction of total distance of AGV can reach to 12.8% compared to the benchmark example.
Zhoushan City Mainland Water Diversion Phase III Project Key Technologies of Cross-sea Pipeline Laying Construction
Authors: Jin Qiwu , Huang Wentao , Huang Yicheng , Wang Xin
Published: June 2021

This paper introduces the cross-sea water transmission pipeline project from Zhenhai to Mamu section of Zhoushan Continental Water Diversion Project Phase III, and summarizes the towing method of the nearshore section of the pipeline laying, the S-Lay, Post-trenching technology and concrete chain row installation construction techniques. Through the summary of the paper, it is expected to provide help for the construction of the sea bottom pipeline for island water supply in the future.
Analysis of physical properties of middle-deep reservoirs in the east of Jizhong Depression
Authors: Li Yuqiong , He Siqi , Zhang Fengming , Wang Ting , Cai Wenhui
Published: June 2021

The Jizhong Depression is one of the hot spots for oil and gas exploration in North China. As the Jizhong Depression has the largest area and richest oil and gas resources, the Raoyang Depression has good prospects for exploration. This paper takes the middle-deep reservoirs of the Shahejie Formation in the Raoyang Depression as the research object. Aiming at the problem of the unclear characteristics of the middle-deep reservoirs in the Raoyang Depression, using core description, thin section identification, and cathodoluminescence technology, the physical properties of the middle-deep reservoirs in Shahejie are clarified. The following points of understanding have been obtained: The rock types of Shahejie Formation in Raoyang area are mainly feldspar sandstone and detrital feldspar, followed by feldspar detrital sandstone and feldspar quartz sandstone. The main mineral content of different structural belts is different. The quartz content in Suning and Maxi areas is higher than that in Liuchu and Dawangzhuang areas. The feldspar content in Liuchu and Dawangzhuang areas is higher than that in Suning, Maxi and Liuxi areas. The Maxi area has the highest lithic content. There are 7 types of pores, including intergranular pores, intragranular pores, granular dissolved pores, mold pores, intergranular dissolved pores, intragranular dissolved pores, and intergranular pores. The porosity in Raoyang area is between 0.85% and 35.26 % with the average value of 12.05%. The permeability is 0.01mD-1312mD, and the average value is 12.75mD. It belongs to low porosity-low permeability reservoirs. Finally, combined with sedimentary facies characteristics and actual drilling and logging data, the reservoir division of the study area is completed, and 10 favorable areas are proposed. The research results provide a reference for the next step in the study of the physical characteristics of the middle and deep reservoirs in the eastern part of the Jizhong Depression.
Study on the Photocatalytic Degradation Rate of Indoor Formaldehyde with Nano-TiO2 Coating
Authors: Yue Yihang , Feng Bo , Du Chun , Wang Yuanhao , Shifeng
Published: June 2021

With the improvement of people’s living standard, diverse home decoration has become popular. However, it results in indoor hazardous gas emission, especially formaldehyde, bringing harm to people’s health. To address this issue, one positive strategy is to remove the hazardous volatile organic compounds through environment friendly nanomaterials. Nano-TiO2 is such a kind of semiconductor material, which can decompose the volatile pollutants via photocatalytic process. In this work, the removal of indoor volatile pollutants by applying home-made nano-TiO2 was studied. The dependence of treatment efficiency of indoor formaldehyde on varying flow rate, coating times, humidity and temperature was systematically investigated. As a result, the highest purification efficiency was achieved when it was coated three times at the relative humidity of 50%. The faster the flow rate, the higher the air purification efficiency. Temperature is also an important factor affecting degradation efficiency, and the degradation has peaked at 22°C. This study demonstrates the effective removal of indoor volatile organic compounds via green nano-TiO2 coating at low cost, and paves way for nanomaterials in applications of indoor environment improvement.
Effect of surface morphology on the mesoporous silicon modified nanofiltration membranes for high rejection performance
Authors: Ding Ying , Liu Dong
Published: June 2021

A new method to prepare composite nanofiltration membrane directly and efficiently by controlling the pore structure and surface morphology of the membrane is proposed in this paper. The fabrication of mesoporous silicon modified polysulfone blend membranes is via a phase inversion method. The structural morphology, surface functional group analysis, elemental analysis, hydrophilicity, chargeability, and nitrogen pollutant (ammonia nitrogen, nitrate nitrogen, total nitrogen) rejection properties of the modified membranes were found to be dependent on the amount of mesoporous silicon incorporated. The combination of the mesoporous silicon framework layer can not only effectively improve the surface structure of the modified membrane with a narrow pore size distribution but also increase the rejection of nitrogen pollutant compared with the pure NF membranes. The mesoporous material can absorb and storage the nitrogenous solution to facilitate the following interfacial polymerization, as well as induce the change of pore radius and surface structure. Compared to those pure NF composite membranes, the modified blend membranes exhibit increased water permeation flux as high as 29.09 L m−2 h−1 at 0.2 MPa. The results show that the optimum doping amount of mesoporous silicon is in the range of 0.5%-1.0%. Characterization studies demonstrated that the addition of the mesoporous silicon leads to decreased membrane pore size. Then, due to the enhanced hydrophilicity of carboxyl and hydroxyl groups on the surface, the electrostatic repulsion between the functional groups and nitrogen pollutant molecules in the membrane results in the enhanced rejection of nitrogen pollutants.
Study on Resistance Coefficient Monitoring of Shallow Hydraulic Tunnel
Authors: Hong-hu Yuan , Shi-peng Haung , Yu Wang
Published: June 2021

The acquisition of elastic resistance coefficient is crucial for the design of shallow hydraulic tunnel. In this paper, the resistance coefficient of the tunnel in the test section of the South Main Canal Project is monitored and analyzed. Considering the actual load mode of the tunnel lining, the load value acting on the lining is measured by the measurement instrument on the spot, and the elastic resistance acting on the tunnel lining is obtained. The elastic resistance coefficient acting on the tunnel lining is obtained through the deformation around the tunnel on the measuring side. The research conclusions and methods can provide reference for the support design of shallow hydraulic tunnel in loose soil layer.
The development overview of wheel-coupler type formwork support
Authors: Li Hang , Jia Shilong , Zhou Fang , Zhao Lei , Su Yanming , Liang Bo
Published: June 2021

As a new type of formwork support, the wheel-coupler type formwork support has been widely used in China, but its research is not comprehensive enough. Therefore, this article introduces the structural characteristics of the wheel-coupler type formwork support and summarizes the current research status. The mechanical properties of the joints are analyzed by finite element analysis, and the analysis results are compared with the disk lock steel tubular scaffold, so as to promote the popularize and use of the wheel-coupler type formwork support.
Development of a Dynamic Information System for Safety Management of Construction Workers Based on IoT and BIM Tools
Authors: Zhang Tiantian , Hao Shengyue
Published: June 2021

In this paper, according to the current situation of safety management of construction workers, BIM and the Internet of Things are jointly applied to the safety management of construction workers, and a safety management system for construction workers is constructed. Solutions are put forward for accident-prone areas, construction personnel’s physical condition, construction personnel’s operation and safety training, hoping to fundamentally and effectively reduce construction personnel safety accidents.
Study on flow field characteristics of undulating member bar in engineering
Authors: Zhao Ruochen , Zhao Meng , Liu Zhen , Jia Tiemei , Kong Fanguang
Published: June 2021

Aiming at the undulating member bar, three kinds of wavelength models are established. The flow characteristics of the undulating member bar with space angle of attack are analyzed by the large eddy simulation method under high Reynolds number, its velocity and pressure distribution with different wavelengths are studied, and the time and frequency domain characteristics of circumferential pressure coefficient, resistance and lift are discussed. The results suggest that the greater the fluctuation of the outer surface of the wave member, the greater the time difference between the maximum and minimum cross-sections; the greater the surface inclination, the greater the change in surface pressure. While the smaller the wavelength, the larger the amplitude of the rod resistance coefficient and the range of the main peak; the larger the wavelength, the slower the attenuation rate of the amplitude peak of the rod resistance and lift coefficient. Combined with the characteristics of the flow field, when the incoming flow has a space angle of attack, the wave cylinder of can achieve a better effect of drag reduction and vibration reduction. Finally, the research results provide important significance and value for the research and application of the flow characteristics of undulating member bar.
Numerical Simulation of Shell and Tube Heat Exchanger Based on Fluent
Authors: Luo Xinyu , Chen Bo , Min Min , Jin Mei , Liu Hongjiao
Published: June 2021

In this paper, the classical shell-and-tube heat exchanger is taken as the research object, and the numerical simulation of the heat exchanger is carried out by using Fluent software. The nephogram of temperature field, velocity field and pressure field on the shell side of the fixed tube-and-plate heat exchanger with different baffle spacing is obtained. The variation law of fluid flow and heat transfer coefficient on the shell side of the heat exchanger with different baffle spacing is analyzed. the ratio of convective heat transfer coefficient ᵅ to the third power of pressure drop ∆pis used as the comprehensive performance evaluation index of the heat exchanger, which has a certain reference for evaluating the comprehensive performance of heat exchanger under different baffle spacing.
High-altitude fall prevention method and device for power transmission line
Authors: Wang Zhigang , Ou Yuexiong , Li Hui , Zeng Wenyuan , Gao Quanzhe , Zou Yu , Li Peng
Published: June 2021

This paper analyzes the structure of transmission line towers and live working conditions, and draws conclusions on the importance and necessity of studying the methods and devices of high-altitude fall prevention for transmission lines. Combining the actual situation of the pole and tower, in view of the poor manufacturing technology of the pole and tower anti-falling track, the size of the anti-dropping device and the track are not matched, and the connection point is misplaced, a new type of adjustable anti-dropping device is developed to address the cross-arm movement of personnel during live work. The alternate use of backup protection ropes and seat belts is cumbersome. An alternative safety rope was developed. Aiming at the transmission line towers without anti-falling tracks, a drone-based high-altitude fall prevention method was developed, and an anti-fall manipulator for high-altitude operations.
Thermal performance of a print circuit heat exchanger in a steam-air test facility
Authors: Zhang Shicheng , Ye Jing , Jin Hongqifei , Yan Xiong , Chi Haomiao , Luan Huibao , Tan Ling
Published: June 2021

Printed circuit plate heat exchanger (PCHE) is a new type of microchannel heat exchanger with high compactness and excellent heat transfer performance. In this study, the performance of a 100×100×200 mm PCHE was evaluated. The thermal hydraulic performance of the PCHE was experimentally investigated in a steam-air heat exchange test setup. Experiments were carried out in the region of 1000<Re<3500. Pressure and temperature at the inlet and outlet of the PCHE were measured during the experiment for both the hot steam and the cold air side. Global Nusselt number correlations were then calculated and regressed from the experimental data. In addition, a full-scaled three-dimensional numerical simulation was performed using CFD method to make more discussion on the friction factors. With these correlations, PCHEs can be further optimized and designed.
Study on the Transformation of I− in Fe2+ Activated PMS System
Authors: Liu Qiang , Miao Jiaqi
Published: June 2021

In order to solve the problem of more and more iodinated by-products in water, the advanced oxidation system of peroxymonosulfate (PMS) activated by ferrous (Fe2+) was used to study the transformation process and principle of iodine ion (I−) as the initial target under different influencing factors in this system. The results showed that when the pH value was 3, the molar concentration ratio of Fe2+ and PMS was 0.8:1, the conversion effect was the best. When the concentration of I− was 20 μmol/L, the conversion rate of I− was 94 %. Under the action of sulfate radical (SO4
−), the final conversion product of I− is only iodate (IO3
−). With the increase of pH value, the conversion effect will also decrease. The concentration of I− itself also affects the reaction.
Analysis of aerodynamic characteristics of the wind turbine tower
Authors: Wang Yihe , Liu Zhen , Liu Yinzhen , Liu Meiying
Published: June 2021

In order to investigate the aerodynamic characteristics of Wind turbine tower under rated operating conditions, a 1:1 numerical model of 1.5MW wind turbine was established using UG finite element modeling software, and the velocity field and pressure field distribution of wind turbine with cross-sections of r / R = 20%, r / R =40%, r / R =60%, r / R =80%, r / R =120% and r / R =140% were analyzed. The results show that with the increase of r / R, the backflow and vortex on the leeward side of the tower are produced to different degrees, and the vortex separation point is shifted backward. With the increase of r / R, the pressure value and range about 0° symmetry axis gradually become smaller, and the pressure values on both sides of the tower show negative pressure and symmetric distribution, and the tail flow area of the tower gradually returns to the inlet pressure.
Study on Dynamic Amplification Factor of UHV Pillar Equipment
Authors: Liu Zhenlin , Zhang Xiaojun , Zhu Zhubing , Xue Yaodong
Published: June 2021

In the research of UHV pillar equipment, the dynamic amplification factor of bracket is a key parameter. This paper mainly focuses on the relationship between the dynamic amplification factor of ceramic equipment under the condition of seismic acceleration response spectrum when the structural parameters of the bracket are the same. In this paper, the stiffness of the bracket is changed by altering the elastic modulus of the steel. The dynamic amplification factors of the speed, displacement, stress and acceleration of the bracket in the two kinds of overall structures are compared and analyzed by numerical simulation. At the same time, the relationship between the bracket frequency and the steel consumption is compared by calculating the steel consumption of different bracket structures. Based on the results of simulation analysis and considering the seismic design of porcelain electrical equipment in UHV substations and converter stations, it is suggested that the dynamic amplification factor, the envelope of displacement and stress amplification factor of 1.40 should be adopted, thus providing a theoretical basis for the design of UHV bracket equipment.
Numerical simulation of heat transfer performance and reliability design of road snow-melting system based on inorganic heat pipe
Authors: Song Jie , Bi Yufeng , Xu Run , Liu Shang , Zhang Changyong , Zhong Guoqiang , Wang Chao
Published: June 2021

In order to study the optimal design parameters of the heat pipe system in the heat pipe snow-melting road structure, a finite element analytical model of the snow-melting road is established based on the heat transfer theory. And based on the analysis of internal heat transfer and surface convective heat transfer of the road, the author set suitable boundary conditions of temperature field according to the actual situation of the road pavement and made quantitative research on the influence of factors such as the evaporating section burial depth and arrangement distance of the heat pipe on the pavement temperature field. The results show that the optimal arrangement distance of the heat pipes is 300-500mm, and when the heat pipe distance is 500mm, the temperatures of the road surface increased slowly, the isotherm of 0°C will no longer continue, and the snow-melting time would become longer; heat pipe burial depth should be determined according to the road structure, the shallower the burial depth the better the snow-melting effect..
Present situation and prospect of new energy vehicle industry in China
Authors: Hao Zhuangzhuang , Li Zhiyang , Ni Hongjun , Lv Shuaishuai , Wang Xingxing , Zhu Yu
Published: June 2021

As the global energy and ecological environment are facing severe challenges, the promotion of new energy vehicles is becoming more and more extensive. This paper introduces the concept and development history of new energy vehicles, summarizes the development status of pure electric vehicles, plug-in hybrid vehicles and fuel cell vehicles in China, further analyzes the development opportunities of new energy vehicle industry, and looks forward to its development prospect based on GM (1,1) grayscale prediction model. Finally, the development suggestions are put forward according to the problems existing in power battery technology, safety, market competition and infrastructure construction of new energy vehicles.
Temporal variation and water quality assessment of Xiaoqing River catchment
Authors: weiyan Pan , Feng Wang , zhen Jiao
Published: June 2021

Xiaoqing River plays an import role in water supply, flood control and ecological protection in Shandong Province. The deterioration of water quality seriously threatens the safety of drinking water for local residents and water ecological environment. In order to investigate the present situation of Xiaoqing River, the cluster analysis was used to study the temporal variation of water quality, and the composite pollution index was used to assess the river water, lake and reservoir water quality. The temporal variation of CODCr, CODMn, total nitrogen, total phosphorus and ammonia in the river water was discussed from the year of 2009 to 2016. The results found that the water quality of Xaiqoing River has improved with time on the whole. The results found that total nitrogen was the major pollutant during all the sampling points. And the Mashang sampling station has the worst water quality. The result can help provide the references for the prevention and control of river water pollution and water ecological imbalance in the Xiaoqing River basin.
Pollution and health risk assessment of arsenic in street dust and soil from an industrial zone
Authors: Cai Ying , Zhang Jingdong
Published: June 2021

Taking an industrial area in Wuhan as the research object, single factor index, Geoaccumulation index and EPA health risk model are utilized to evaluate the pollution pattern and health risk of arsenic (As) in street dust with different particle fractions and soil. The results showed that the content of As in street dust increased with the decrease of particle size. The average content of As in street dust with fine particle fraction and soil exceeded the soil background value of Hubei Province, but did not exceed the screening value of “Soil Environmental Quality Construction Site Soil Pollution Risk Control Standards (Trial)”. The content of As in soil had a high correlation with that of dust with < 63 particle fraction at the corresponding point, with high fit degree (R2=0.6012). There was moderate to heavy pollution of As in areas surrounding industrial enterprises like Wuhan Iron and Steel, cement plants, and areas with high traffic flow and construction sites. The As of street dust and soil at some points posed a non-carcinogenic risk to children, but no carcinogenic risk. The ingestion pathway was the largest non-carcinogenic exposure route of As in street dust and soil from the research area.
Study on Tunnel Fire Smoke Control and Transverse Passageway Interval under Traffic Congestion
Authors: Liu Shuai
Published: June 2021

When there are traffic jams in the tunnel, if the critical velocity is used for longitudinal smoke exhaust, it will pose a threat to the vehicles and people congested downstream. Using FDS + EVAC for numerical simulation, this paper has studied the fire smoke control strategies and transverse passageway intervals. The results show that: (1) When there is congestion at the downstream of the fire source, excessive longitudinal smoke exhaust will reduce the available safe evacuation time (ASET) in the downstream area of the fire source, and the longitudinal velocity should be controlled within 1 m/s. (2) When the transverse passageway for vehicles cannot be used for evacuation, the time necessary for safe evacuation increases by 43%. In order to ensure the safe evacuation, the transverse passageway intervals should be no more than 400m, and the transverse passageway for vehicles should have the function of pedestrian evacuation.
Field study on thermal environment and thermal adaptability of classrooms in Hefei area universities
Authors: Li Wei , Fu Kousuo , Shui Taotao , Gao Guotai , Yin Linjian , Wan Xiaokang , Lv Kefeng
Published: June 2021

In order to study the thermal environment and thermal comfort of university classrooms, a long-term on-site study of a university classroom in the Hefei area is carried out by combining questionnaires and on-site data collection. A thermal sensory model applicable to the university classroom in the Hefei area is established, and through analysis it is found that the measured thermal neutral temperature is lower than the predicted thermal neutral temperature under the PMV model, and the corresponding 90% acceptable temperature ranges under the measured and PMV models are 22.0~25.6°C and 17.2-24.9°C respectively. Opening and closing doors and windows and adding and removing clothing are the preferred thermal adaptive behaviors of the subjects when the indoor thermal environment changes.
Research on Highway Traffic Event Detection Method Based on Image Processing
Authors: Bao Lixia , Wang Qiulan , Qu Wenliang , Mo Xianglun
Published: June 2021

Aiming at the problem of the image processing technology of the expressway event detection system, this paper uses the background subtraction method and Camshift algorithm to detect and track the moving vehicle. Through sorting out the traffic event detection and processing process of Lian-Xu Expressway, the traffic event detection system is constructed, and the data processing module of the system is mainly studied to realize the detection and alarm of traffic events. The results show that the highway traffic incident detection system studied in this paper can complete the detection of traffic events in the video, improve the detection rate, and provide technical support for the highway safety management.
Characterization of edge damage induced on REBCO superconducting tape by mechanical slitting
Authors: Hartnett William N , Ramirez Javier , Olson Tanner E R , Hopp Christopher T , Jewell Matthew C , Knoll Allan R , Hazelton Drew W , Zhang Yifei
Published: June 2021

Rare-earth barium-copper-oxide (REBCO) superconductors are high-field superconductors fabricated in a tape geometry that can be utilized in magnet applications well in excess of 20 T. Due to the multilayer architecture of the tape, delamination is one cause of mechanical failure in REBCO tapes. During a mechanical slitting step in the manufacturing process, edge cracks can be introduced into the tape. These cracks are thought to be potential initiation sites for crack propagation in the tapes when subjected to stresses in the fabrication and operation of magnet systems. We sought to understand which layers were the mechanically weakest by locating the crack initiation layer and identifying the geometrical conditions of the slitter that promoted or suppressed crack formation. The described cracking was investigated by selectively etching and characterizing each layer with scanning electron microscopy, laser confocal microscopy, and digital image analysis. Our analysis showed that the average crack lengths in the REBCO, LaMnO3 (LMO) and Al2O3 layers were 34 μm, 28 μm, and 15 μm, respectively. The total number of cracks measured in 30 mm of wire length was between 3000 and 5700 depending on the layer and their crack densities were 102 cracks mm−1 for REBCO, 108 cracks mm−1 for LMO, and 183 cracks mm−1 for Al2O3. These results indicated that there are separate crack initiation mechanisms for the REBCO and the LMO layers, as detailed in the paper. With a better understanding of the crack growth behavior exhibited by REBCO tapes, the fabrication process can be improved to provide a more mechanically stable and cost-effective superconductor.
Spatially explicit life cycle assessment of fish: comparison of local vs imported provision in Wisconsin
Authors: Ghamkhar Ramin , Hicks Andrea
Published: June 2021

The global fish supply chain handles ∼179 million tons of product annually (as in 2018). Transportation and distribution are an important part of fish supply chain, as fish and shellfish are one of the largest globally traded food commodities with a trading value of ∼$153 billion in 2017. Here we show that disregarding the environmental impacts of fish transportation, either land transit or flight, neglects a noteworthy portion of total fish provisioning environmental impacts. We identified that local fish provision, considering (1) all Wisconsin counties as production points, (2) cities of Chicago, Milwaukee, and Minneapolis as consumption points, and (3) effective, semi-effective, and ineffective space heating approaches, has significantly lower environmental impacts than imported fish provision, considering flight transportation from offshore production points. Meaning the necessity to elevate local fish production capacity to enhance the environmental sustainability of fish provision is essential, despite potential elevated heating demands for cold-weather aquaculture.