Engineering Background Research Articles

Global aviation contrail climate effects from 2019 to 2021

Abstract. The current best-estimate of the global annual mean radiative forcing (RF) attributable to contrail cirrus is thought to be 3 times larger than the RF from aviation's cumulative CO2 emissions. Here, we simulate the global contrail RF for 2019–2021 using reanalysis weather data and improved engine emission estimates along actual flight trajectories derived from Automatic Dependent Surveillance–Broadcast telemetry. Our 2019 global annual mean contrail net RF (62.1 mW m−2) is 44 % lower than current best estimates for 2018 (111 [33, 189] mW m−2, 95 % confidence interval). Regionally, the contrail net RF is largest over Europe (876 mW m−2) and the USA (414 mW m−2), while the RF values over East Asia (64 mW m−2) and China (62 mW m−2) are close to the global average, because fewer flights in these regions form persistent contrails resulting from lower cruise altitudes and limited ice supersaturated regions in the subtropics due to the Hadley Circulation. Globally, COVID-19 reduced the flight distance flown and contrail net RF in 2020 (−43 % and −56 %, respectively, relative to 2019) and 2021 (−31 % and −49 %, respectively) with significant regional variations. Around 14 % of all flights in 2019 formed a contrail with a net warming effect, yet only 2 % of all flights caused 80 % of the annual contrail energy forcing. The spatiotemporal patterns of the most strongly warming and cooling contrail segments can be attributed to flight scheduling, engine particle number emissions, tropopause height, and background radiation fields. Our contrail RF estimates are most sensitive to corrections applied to the global humidity fields, followed by assumptions on the engine particle number emissions, and are least sensitive to radiative heating effects on the contrail plume and contrail–contrail overlapping. Using this sensitivity analysis, we estimate that the 2019 global contrail net RF could range between 34.8 and 74.8 mW m−2.

Research on process parameter optimization of irregular coal face.

Based on the engineering background of 1353 working face in Daizhuang Coalmine, the paper identifies three primary issues with the working face mining process: conventional pressure relief means are limited, risk of impact and the length of working face changes, It also proposes comprehensive control measures to improve the blasting roof cutting scheme, optimize mining speed and the location of the stopping line. The three improvement measures mentioned above are simulated numerically, and the effects of the drilling and blasting plan, mining speed, and stopping line location on stress distribution are determined. The results show that by implementing the three improvement measures, the stress variation interval can be efficiently controlled and the working face's production safety can be increased. Finally, it is determined that the 1353 working face of Daizhuang Coalmine adopts the pressure relief method of drilling on one side and cutting the roof 20m deep on the other side, and the mining speed of the working face is 3m/day and the length of the stopping line is 85m. Based on the on-site monitoring results, the implementation of comprehensive treatment measures can effectively improve the surrounding rock state of 1353 working face, which has certain guiding significance for the mining of irregular working face.

Construction of a virtual simulation practical teaching system for intelligent manufacturing under the background of new engineering

AbstractTo adapt to the new direction of engineering education reform in China under the background of new engineering, and to promote the transformation and upgrading of intelligent manufacturing professionals, a virtual simulation practice teaching system based on Internet technology is constructed. Relying on “online + offline” resources, experimental modules are designed, a course resource library is built, a digital cloud platform is developed, and a “One Body, Two Wings” virtual simulation teaching and training system is established. Practice has shown that the virtual simulation system has the advantages of immersion, interaction, imagination, and reality, which can meet the basic needs of users and provide a safe and immersive experimental operation experience. The comparative data on practical effectiveness shows that virtual simulation teaching has significantly improved students' theoretical knowledge, practical skills, and innovative ability, making graduates highly desirable by enterprises. The virtual simulation system not only enhances user experience, but also improves students' learning effect, professional cognitive ability, and professional practice ability. The system provides strong technical support for the cultivation of intelligent manufacturing professionals, and is an efficient and practical tool in the field of teaching and training, with broad application prospects.

Using linkography to understand the thinking differences of designers between engineering and art backgrounds in the early stages of the design process

In China, industrial designers are usually educated with engineering background while product designers are educated with art background. Despite these educational differences, both of them are adept at tackling design-related issues. However, different educational backgrounds can affect the idea generation, especially in the early stages of the design progress. This study investigates the thinking processes of designers between engineering and art backgrounds in the early stages of the design process. Designers are encouraged to express ideas verbally or by sketching, and linkography was used to visually depict the designer’s thinking process. Subsequently, with the help of vertical transformation value and the chunk, the features in the thinking of the two types of designers are explored, including: 1) In most cases, the vertical transformation value of the product designer is higher than that of industrial designer, which indicates that product designer is better at the reflection in design. 2) The chunk patterns in the linkographs show that industrial designers prefer to decompose tasks into sub-tasks and solve them individually, while product design participants tend to solve problems as a whole from a global view. These findings can enlighten the future research directions for design education and design organizations in multidisciplinary backgrounds.

Study on Grouting Repair and Reinforcement Technology of soft Foundation of large diameter Highway Tunnel

Taking the uneven settlement of the foundation of a two-way eight-lane large diameter highway tunnel as the engineering background, the joint grouting reinforcement technology of miniature steel pipe pile and steel sleeve valve pipe is put forward. based on the field measured settlement data and foundation core samples, the effectiveness of repair and reinforcement is analyzed. The research results show that the combined grouting of miniature steel pipe pile and steel sleeve valve pipe can effectively control the settlement of tunnel foundation, and significantly improve the RQD (Rock Quality Designation) value of tunnel foundation, which provides technical reference and basis for the construction of similar projects.

Study on Reinforcing Anchor Cable Support in Overreach Section of Deep Roadway

With the increasing depth of coal mining, the conditions of deep working face are becoming more and more complex, the stability of surrounding rock of roadway is getting worse and worse, and the problem of deep roadway support is becoming more and more prominent. In this paper, the 24100 working face of Pingdingshan No.11 Coal Mine is taken as the engineering background. In view of the problems of roof crushing and deformation and more net pockets in the return airway affected by the mining of the working face, the grouting anchor cable reinforcement and support technology in the advance section of the deep mining roadway is proposed, and the feasibility of the support effect is verified by numerical simulation. The results show that the influence range of the advance abutment pressure of the air roadway is about 60 m, and the reinforcement support strength required for the roof of the roadway is 50.6 kN/m2. The grouting anchor cable reinforcement support technology system of the return air roadway can control the deformation of the surrounding rock of the roadway and achieve safe and efficient mining.

Research on Curriculum Construction of Artificial Intelligence Under the Background of New Engineering

Under the background of new engineering, artificial intelligence courses in applied undergraduate colleges and universities face great challenges in course teaching and students’ learning effect due to the comprehensive factors such as content, class hours, and students’ knowledge structure. In order to improve the level and quality of talent training, this paper explores and practices the problems existing in the teaching of artificial intelligence courses in applied undergraduate colleges from the aspects of curriculum teaching objectives, contents, methods, teacher construction, and experimental teaching, promoting learning through competition and teaching assessment, and insists on taking “applied and innovative” learning training as the center. It is necessary to constantly optimize the ideas and methods of artificial intelligence course construction, and promote the development and innovation of computer education in application-oriented colleges under the background of new engineering.

Research on the Curriculum System of Top-up Degree Programs under the Background of New Engineering and Technical Disciplines

In response to the new round of technological revolution and industrial transformation, and to support and serve innovation-driven development, new engineering talents focus on the cultivation of practical and innovative abilities. At present, the proportion of upgrading from junior college to undergraduate in China has reached 20%. More and more vocational school graduates have the opportunity to receive high-quality undergraduate education, become skilled professionals. But the cultivation of this group of students is often overlooked by many universities. This study analyses the issues existing in the undergraduate curriculum system of local applied universities in undertaking vocational education. It is pointed out that the application of ordinary undergraduate curriculum systems is not suitable for vocational-to-bachelor s students and cannot meet the training objectives of higher vocational and technical talents. To cultivate new engineering vocational and technical talents, aiming at the current issues in the theoretical and practical settings of the curriculum system, this study proposes to use employment as a guide in the vocational-to-bachelor s curriculum system, set bridging courses to consolidate professional foundations, implement multiple training programs to promote student development, and collaborate with enterprises to carry out project-based practical training. It is necessary to optimize the construction of the curriculum system from theoretical and practical, and fully leverage the advantages of students strong practical abilities, which will reserve high-level vocational and technical talents for the new round of technological and industrial revolution.

Experimental Study on Shear Lag Effect of Long-Span Wide Prestressed Concrete Cable-Stayed Bridge Box Girder under Eccentric Load

Based on the engineering background of the wide-width single cable-stayed bridge, the shear lag effects of the cross-section of these bridge box girders under the action of the eccentric load were experimentally studied. The behavior of shear lag effects in the horizontal and longitudinal bridge directions under eccentric load in the operational stage of a single cable-stayed bridge was analyzed by a model testing method and a finite element (FE) analytical method. The results showed that the plane stress calculation under unidirectional live load was similar to the results from spatial FE analysis and structural calculations performed according to the effective flange width described in the design specification. At the position of the main beam near the cable force point of action, the positive stress at its upper wing edge was greatest. At a distance from the cable tension point, the maximum positive stress position trend showed that from the center of the top flange to the junction of the top flange and the middle web to the junction of the top flange and the middle web and the side web. Under eccentric load, the positive and negative shear lag effects on the end fulcrum existed at the same time, and the shear lag coefficient on the web plate was larger than the shear lag coefficient on the unforced side. Due to the influence of constraint at the middle fulcrum near the middle pivot point, positive and negative shear lag effects were significant, and the coefficient variation range was large, resulting in large tensile stress on the roof plate in this area. According to FE analytical results, stress and shear forces of a single box three-chamber box girder under eccentric load were theoretically analyzed, the bending load decomposed into the accumulation of bending moment and axial force, using the bar simulation method, and the overall shear lag effect coefficient λ was obtained and verified.

Experimental study on the deformation and failure mode of surrounding rocks of a tunnel in a jointed rock mass

The existence of jointed rock masses in tunnels is a key problem that leads to the deformation and instability of the surrounding rock. Based on the engineering background of the Qingdao Metro, a physical model and a numerical model are constructed to analyze the mechanism of deformation and instability of the surrounding rock of a jointed tunnel using model blocks that conform to the characteristics of joint distribution. The results show that during the whole test process, the cracks between the blocks in the tunnel arch are in the “development − stability − closure − penetration” state. Finally, the block falls in the left area of the tunnel, and the corresponding anchor axial force transits from the linear growth stage to the steady growth stage. After the axial force of the rock bolt suddenly decreases in the loading stage, the bolt enters the stability stage, and finally, S-shaped failure occurs when the surrounding rock is unstable. Under the action of a prestressed rock bolt, the normal stress and radial stress of the rock mass increase, and the difference between the major and minor principal stresses decreases significantly. The radial stress on the surrounding rock surface of the arch is approximately 8 % greater than that in the traditional rock bolt scheme, which improves the strength reserve of the rock mass. In the field test, the prestressed rock bolt can control the deformation of the surrounding rock in the arch within 2 ∼ 5 mm, which provides a reference for the control of the surrounding rock in jointed tunnels.

Dynamic Stability Analysis of Subsea Tunnel Crossing Active Fault Zone: A Case Study

The rock strength in an active fault zone is low and the surrounding rock is fractured and has poor stability, making any subsea tunnel crossing the active fault zone extremely susceptible to disasters such as tunnel collapse, sudden water ingress, and mud inrush. This poses a potential threat to the construction project, making the dynamic stability analysis of a subsea tunnel crossing an active fault zone of great significance. This study takes the second subsea tunnel crossing the Cangkou Fault in Jiaozhou Bay as the engineering background and conducts numerical simulations by employing different lining stiffnesses for tunnel excavation, as well as applying dynamic loads. The dynamic stability of the subsea tunnel crossing the active fault zone is evaluated by comparing and analyzing the lining’s displacement, peak acceleration, and stress characteristics. This study explores the disaster-causing mechanisms of active fractures, determining that the hazard of orthogonal misalignment in an active fault zone is the least severe, while the hazard of opposite misalignment is the most severe. This research provides a basis for disaster prevention and mitigation in active fracture zones.

Study on Pretightening Loss Effect of Bolt Support in Deep Soft Rock Roadway

The magnitude of pretension force serves as an important indicator of the effectiveness of anchor bolt active support and is one of the significant factors influencing the stability of tunnel surrounding rock. Therefore, in practical engineering, it is crucial to establish the relationship between pretension torque and pretension force. However, current research in this field has some limitations. With a specific mine in western China as the engineering background, this paper first analyzed the influence factors of surrounding rock deformation and failure, established a mechanical model for pretension structure of anchor bolt support, and derived the quantitative relationship between pretension torque and pretension force based on hypothetical conditions. Finally, it proposed the loss effect of anchor bolt support and modified the pretightening loss coefficient for engineering application. The research results show that the actual pretightening force of anchor support is lower due to the influence of deep soft coal seam, which leads to failure of coal pillar under mining stress. The loss effect of surrounding rock on pretightening force was represented by a coefficient k, and the modified value of the coefficient was calculated as 0.19∼0.43. By applying the modified relationship between pretightening torque and pretightening force, it was found that the actual pretightening torque of 300 Nm applied to 11307 return air roadway effectively controlled surrounding rock deformation and failure, with coal pillar displacement less than 120 mm.

Experimental Study on the Effect of Rock Mechanical Properties and Fracture Morphology Features on Lost Circulation

Summary At present, lost circulation remains a complicated drilling problem in fractured formations that needs to be addressed urgently. However, the influence of actual rock mechanical properties (RMP) and fracture morphological features (FMF) on lost circulation is easily ignored in the current research on leakage mechanism and evaluation, which may lead to deviation from the analysis results, thus affecting the success rate of plugging treatments. Therefore, the complicated effects have been investigated using the improved plugging experimental instruments in this paper. The results indicate that both RMP and FMF have a prominent influence on the plugging and sealing effects of plugging slurries. This research suggests that the bridging and plugging capabilities of the slurry can be improved by increasing the type and amount of lost circulation materials (LCM). Moreover, depending on the fracture morphology difference, the same plugging slurry will have different plugging effects on the same width-size opening fracture channel. In addition, a novel evaluation method is developed to assess the effective sealing ability of plugging slurry against formation fractures, which has been successfully applied in the field. To the best of our knowledge, this is the first evaluation method that investigates simultaneously the mechanical properties of rocks and fracture characteristics of formations. The novel evaluation method incorporates the critical parameters of the lost circulation effect into the design of the plugging evaluation model. Thus, the proposed method can be used to quantitatively evaluate the plugging capability of the LCM and slurries and the loss capacity of the loss channels. However, the higher plugging coefficient (λ) of the slurry does not necessarily mean that the plugging slurry has a stronger plugging capacity (SP). Adopting the suitable fracture channel model can avoid overestimating or underestimating the plugging capability of the LCM slurries. Therefore, it is necessary to improve the formula design of the LCM slurry in combination with the geological engineering background. This perception has significant implications for the analysis of the lost circulation mechanisms and the optimization formula design of the plugging slurries.

Dynamic damage and fracture mechanism of curved ripper cutting reinforced concrete composites: Numerical simulation combined with engineering practice

Shield tunnels inevitably cross existing structures like reinforced concrete pile foundations and concrete walls due to the spatial interlocking of underground structures in the construction process. The objective of minimizing cutter damage during the cutting of reinforced concrete pile foundations is widely pursued in engineering. In this study, a numerical model of curved ripper cutting reinforced concrete composites was established, with the engineering background of Nanjing Metro Line 10 shield tunnel crossing the pile foundation of Youth River Bridge. The dynamic damage and fracture of reinforced concrete composites under the cutting of single, double, and multiple rippers were comprehensively investigated. The effects of the operating parameters and geometric parameters on the cutting performance were discussed. Finally, a statistical analysis was carried out to evaluate the damage of 148 rippers and the fracture of rebar in an actual engineering project. The simulation results reveal that coordinated cutting of five rippers has optimized the fracture mechanism of the rebar, weakening the compression effect between the ripper and the rebar, and highlighting the tensile fracture of the rebar. It is appropriate to set the alloy blade angle at 90° and the blade width at 10 mm for practical engineering applications. The penetration has a significantly greater influence compared to cutting speed. In practical engineering, adopting a low penetration and high rotation speed grinding mode is advantageous for reducing blade fractures. The central fishtail cutter and the rippers in the outer area of the cutterhead are more prone to damage during the pile cutting process and warrant additional reinforcement measures. The findings provide comprehensive and innovative insights into shield cutting reinforced concrete pile foundations.

A scientist for president.

If elected, Claudia Sheinbaum Pardo would bring an extensive background in science and engineering to Mexico's presidency. But many researchers are anxious about how she would govern.

Study on the escaping condition of backfill grouting based on two-phases flow for shield tunnelling during whole section rock

During the process of full section surrounding rock shield tunneling, the occurrence of synchronous grout escaping can seriously affect the assembly quality of the detached shield tail segment ring. The segment is prone to quality accidents such as floating, misalignment of the tunnel pipes, and even cracking, and even a large number of rock fractures in the shield tail gap mix with water flow towards the excavation face and pressure chamber, leading to frequent fissure water gushing out of the screw conveyor. Taking the shield tunnelling section of Nanjing Metro Line 6 as the engineering background, this paper uses the finite element software Ansys Fluent to establish the two-phases flow shield tail escaping grout model, and analyzes the influence laws of the grout properties, grouting pressure difference, grouting escaping thickness and other factors in the process of grout escaping behind the shield tail wall based on Bingham fluid. The results show that the amount of synchronized grout escaping increases linearly with the increase of grouting pressure difference and grouting escaping thickness, and decreases with the increase of grout shear yield stress. The paper also discusses the three-dimensional curved surface of grout escaping volume, grouting pressure difference and grouting fluid properties behind shield tunnel tail in a full section surrounding rock shield project of Nanjing Line 6, and gives the measures to prevent grout escaping when the allowable grout escaping volume is not more than 1m3: when the grouting escaping thickness is 20mm, the grouting pressure difference should be controlled within 0.20∼0.25MPa, and the shear yield stress of the grouting fluid should be controlled within 300∼350Pa.

Differential roof cutting for roadway support in dual gob-side entry retention on a single working face − Multilevel continuous anchor-grouting control technology: A case study

The coal pillar-free gob-side entry retention technology (GER), which enhances resource recovery rates and reduces the amount of tunnel excavation, has been applied in multiple mining areas in China. However, cases of implementing gob-side entry retention on both sides of a single working face are rare. The asynchronous extraction of long-distance working faces leads to significant differences in the stress environment of roadways on both sides, and uniform technical means are poorly adapted to the control of surrounding rock on both sides, affecting the safe and efficient production. This paper, taking the dual gob-side entry retention on both sides of the 61001 W working face with thick mudstone roofs in Zhao Guan Coal Mine, Shandong Province, as the engineering background, utilizes a combination of theoretical calculations, numerical simulations, and on-site detailed monitoring to analyze the uncoordinated deformation characteristics of the upper part bulging and the lower part concaving of the two roadways. It clarifies the differentiated spatiotemporal evolution law of the number of fractures and the development turning points at different depths of the surrounding rock of the two entries, revealing the differential deformation mechanism of the surrounding rock of the two entries caused by stress state and fracture development differences. A “cutting roof to relieve pressure-multilevel continuous anchor-grouting” combined control technology system is proposed. By cutting off the stress transmission of the roof through drilling and blasting, and then reconstructing the integrity of the surrounding rock and improving the rock strength with the help of anchor-grouting. With the application of this new technology, the deformation of the surrounding rocks of the two entries was reduced by more than 60 % and 29 %, respectively, and the maximum crack depth of the roof was controlled within 3 m, significantly enhancing the stability of the roadways. The research results of this paper provide a reference for the control of surrounding rock in gob-side entry retention under similar conditions.

Research on Practical Teaching of Traffic Information Analysis and Application Course under the Background of New Engineering

Research on Practical Teaching of Traffic Information Analysis and Application Course under the Background of New Engineering

“How to Bridge the Gap”: Empowering Early-Career Scientists to Navigate the Science-Policy Interface—Conclusions from a Summer School

The “Science and Policy - How to Bridge the Gap” summer school, which took place in July 2023 in Switzerland, aimed to educate PhD students in natural science and engineering on engaging with policymakers effectively. Over the course of five days, the program covered various aspects of the Swiss and international science-policy interface, including the Science for Policy framework, concrete examples of evidence-based policy advice from scientists, and talks on the significance of Open Science (OS) and public engagement in fostering the dialogue between science and society. Additionally, multiple workshops illustrated science communication formats for different audiences, such as policymakers, stakeholders, and the general public. Organized by five PhD students with a natural science and/or engineering background, the event brought together thirty participants and featured twenty-eight speakers, creating a highly international and stimulating learning environment. This workshop review, written by the summer school organizers, summarizes the school’s outcomes and aims to provide valuable insights for early-career scientists and engineers taking their first steps in science-informed policymaking. The roles scientists may play at the science-policy interface, the various meeting points (physical and ideological) to interact with decision-makers, tools for more effective communication with non-expert audiences, and the importance of OS and Citizen Science (CS) in integrating scientific information more widely into society are discussed. Based on the participants’ feedback, suggestions are also offered for future events on science and policy, which early-career researchers can implement in their respective universities and countries. Given the strong commitment of participants and their desire to create a community, the authors believe such workshops are essential to give early-career scientists the tools and network to actively engage in the science-policy landscape.

Mechanical Response and Stability Optimization of Shallow-Buried Tunnel Excavation Method Conversion Process Based on Numerical Investigation

Different excavation methods lead to substantial changes in the relaxation zone of the surrounding rock. The stress characteristics of the support structure become more complex during the process of excavation method conversion. It is essential to design a well-considered construction plan to minimize the disruptions caused by excavation method conversion. This work takes a tunnel in Jiangsu Province, China, as the engineering background and establishes a numerical model for the conversion from the double-side-drift method to the three-bench method. Based on a numerical investigation, this study analyzed the deformation of surrounding rock and the stress state of the support structure during the excavation method conversion. The results showed that excavation method conversion can accelerate the deformation rate of the surrounding rock, causing the support structure to bear greater pressure. This leads to a significant increase in the circumferential stress at the junction of two excavation methods. Setting up a reinforced area during the process of excavation method conversion can improve the stress state of the support structure. Finally, an analysis of the parameters of the reinforced area was conducted, and a reasonable construction plan was proposed. This study can provide guidance for subsequent construction projects.