Engineering Situations Research Articles

The Recent Progress China Has Made in High-Concentration Backfill

With the development of science and technology, backfill technology has made continuous progress, and the traditional backfill method is no longer suitable for various complicated practical engineering situations. Therefore, researchers in the field of backfill mining have gradually shifted their research focus to the study of high-concentration backfill, and Chinese researchers are no exception. In order to solve the problems caused by the traditional backfill method, China began to vigorously develop high-concentration backfill in recent years, and achieved a lot of results. In this paper, some important achievements made by Chinese researchers on high-concentration backfill in recent years are reviewed; it also presents a summary report of the latest research results from several key laboratories across China. Therefore, this paper reviews the development progress of high-concentration backfill China has made, of which the main contents include: (1) research progress of the high-concentration backfill theory in China; and (2) research progress of high-concentration backfill equipment in China. Finally, we claim that this paper serves just as a guide to start a conversation, and we hope many more experts and scholars will be interested and engage in the research of this field.

Efficient local adaptive Kriging approximation method with single-loop strategy for reliability-based design optimization

The classical reliability-based design optimization (RBDO) methods, due to the ever increasing complexity of designs and contingent engineering situations, incur more and more intricate numerical models. The consequent intractable computational intensity has imposed great challenges for practical application of RBDO. Thus, the surrogate-based RBDO methods, and especially those using Kriging model, have received widespread attention recently for their superior computational efficiency without compromise of computational accuracy. On the other hand, the Kriging-based RBDO methods still ensue high computational demands for complex RBDO problems and especially those with implicit objective and constraint functions. To enhance the computational efficiency of the Kriging-based RBDO methods, this study proposes an efficient local adaptive Kriging approximation method with single-loop strategy (LAKAM-SLS), in which Kriging models are employed to replace both the objective and constraint functions. Two different criteria are developed to identify whether Kriging model of performance function in probability constraint is active in each iteration. If the criterion is satisfied, approximate inverse most probable point (IMPP) derived by combining sing-loop approach with Kriging will be used to refine the corresponding Kriging model. For the objective function, its Kriging model is sequentially refined through points selected by a newly proposed learning function from the sample pool generated by taking the optimal solution from each iteration as the sampling center. Four benchmark examples and an application example of head pressure shell are implemented to evaluate the computational performance of the currently proposed LAKAM-SLS against other Kriging-based RBDO methods. The result comparison shows that the currently proposed LAKAM-SLS substantially reduces the computational expense to a relatively low level.

Questionnaire survey for grasping the current situation of clinical engineers regarding drug treatment at the time of extracorporeal circulation device

Questionnaire survey for grasping the current situation of clinical engineers regarding drug treatment at the time of extracorporeal circulation device

Accelerating particle-resolved CFD simulations of catalytic fixed-bed reactors with DUO

Simulation of fixed-bed catalytic reactors is important for engineering industrial technologies. The large number of catalytically active surface faces makes the application of microkinetic models too time consuming for large 3D simulations that include fully resolved particle structures (e.g., ≫ 10′s of particles). Such simulations, though, are often required for small tube-to-particle diameter ratio configurations, where local flow effects are difficult to capture with 1D or 2D simulations. A common solution for speeding up reactive computational fluid dynamics (CFD) involves the use of chemistry acceleration methods, including In-Situ Adaptive Tabulation (ISAT) and Cell Agglomeration (CA). In the present contribution, DUO (DETCHEMTM + OpenFOAM coupling) CFD software has been extended to include ISAT and CA methods for surface reactions, in particular, using a CA method that is simpler than other implementations of this acceleration technique. Speedup factors and errors were tabulated for an 86 spherical particle 3D resolved fixed-bed reactor, considering the exothermic methane catalytic partial oxidation (CPOX) and the endothermic dry reforming of methane (DRM) chemistries. For CPOX, a speedup factor of ∼ 7x was achieved, while for DRM, a speedup of ∼ 35x was obtained, with both cases achieving an acceptable error in the solution. Although a tighter error tolerance with ISAT and CA is shown to reduce the overall calculation error, for some engineering situations this tradeoff in speedup and accuracy will be acceptable. Achieving usable results in around 0.5 – 2 h instead of around 20-hours (for these chemistries on this particular grid, run on a 400-core cluster) can vastly improve the feasibility of computational fluid dynamics for the analysis of fixed-bed catalytic reactors including microkinetics mechanisms.

Discussion on the Present Situation and Development Direction of Intelligent Mechanical Engineering

Discussion on the Present Situation and Development Direction of Intelligent Mechanical Engineering

The Periodicity of the Accuracy of Numerical Integration Methods for the Solution of Different Engineering Problems

Newton-Cotes integration formulae have been researched for a long time, but the topic is still of interest since the correctness of the techniques has not yet been explicitly defined in a sequence for diverse engineering situations. The purpose of this paper is to give the readers an overview of the four numerical integration methods derived from Newton-Cotes formula, namely the Trapezoidal rule, Simpson's 1/3rd rule, Simpson's 3/8th rule, and Weddle's rule, as well as to demonstrate the periodicity of the most accurate methods for solving each engineering integral equation by varying the number of sub-divisions. The exact expressions by solving the numerical integral equations have been determined by Maple program and comparisons have been done using Python version 3.8.

Mathematical Evaluation on the Control of Mining-Induced Ground Subsidence in Thick Loose Strata.

Coal mining under thick loose strata in North China leads to ground subsidence, which is a natural result of hydromechanical coupling (fluid flow coupled with solid deformation). Therefore, the land surrounding the mining areas is greatly damaged. In this study, the combined weight (CW) method and the fuzzy matter-element analysis (FMEA) method were used to analyze and evaluate the control effect of subsiding land. Overall, 20 sets of geological samples were collected from this area. The influencing factors and the corresponding weights for the control effect of subsiding land were comprehensively analyzed, and an FMEA model was built to predict and verify the results. The results showed that (1) the two evaluation indicators with the most significant impact on land reclamation were the degree of integration and the economic and social benefits and (2) among the 20 sets of samples selected, the predicted conclusions of 17 sets were consistent with the actual engineering situations, which led to an accuracy of 85%. In other words, the CW-FMEA model showed good reliability for evaluating the control effect of subsiding land, which can provide scientific references for control and quality evaluations of land subsidence due to coal mining.

Free and Forced Wave Motion in a Two-Dimensional Plate with Radial Periodicity

In many practical engineering situations, a source of vibrations may excite a large and flexible structure such as a ship’s deck, an aeroplane fuselage, a satellite antenna, a wall panel. To avoid transmission of the vibration and structure-borne sound, radial or polar periodicity may be used. In these cases, numerical approaches to study free and forced wave propagation close to the excitation source in polar coordinates are desirable. This is the paper’s aim, where a numerical method based on Floquet-theory and the FE discretision of a finite slice of the radial periodic structure is presented and verified. Only a small slice of the structure is analysed, which is approximated using piecewise Cartesian segments. Wave characteristics in each segment are obtained by the theory of wave propagation in periodic Cartesian structures and Finite Element analysis, while wave amplitude change due to the changes in the geometry of the slice is accommodated in the model assuming that the energy flow through the segments is the same. Forced response of the structure is then evaluated in the wave domain. Results are verified for an infinite isotropic thin plate excited by a point harmonic force. A plate with a periodic radial change of thickness is then studied. Free waves propagation are shown, and the forced response in the nearfield is evaluated, showing the validity of the method and the computational advantage compared to FE harmonic analysis for infinite structures.

Enhanced landfill's characterization by using an alternative analytical model for diffusion tests.

Landfills have been extensively used as waste deposits in most of the big cities in the world. Therefore, considerably large urban areas have contamination threats. Engineering solutions applied to prevent or contain soil, and water contamination often involve the application of liners, which are low permeability barriers made of materials such as compacted clay and geomembranes. In many liner applications, once reduced rates of seepage are expected, diffusion has proved to be relevant, if not dominant, to the process of contaminant transport. Normally, diffusivity parameters can be assessed by a single-reservoir pure diffusion test, where a contaminant solution is placed above a saturated soil sample and the solution's concentration is monitored over time. Once the temporal variation of concentration is measured, the process of back-calculating diffusivity parameters is not standardized. In this paper, an analytical model of the diffusive transport of contaminants is revisited considering the initial and boundary conditions of the pure diffusion test. In this model, the contaminant solution reservoir is included in the analysis domain as an equivalent contaminated soil layer. The analytical solution relies on a series evaluation, which may be a drawback to everyday engineering situations. Therefore, we build a high-accuracy exponential approximation to the solution. Expedited evaluation procedures are proposed to provide reasonable estimates for the fitting parameters. Also, in order to illustrate the applicability of the new solution, test datasets of a soil around the Jockey Club Landfill (JCL) site, one of the major landfills in Latin America, have been modeled. We discuss possible issues of considering linear isotherms to model the sorption characteristics of soils, indicating that convex isotherms, if linearly modeled, may lead to overestimated values of the diffusivity parameter.

An analysis of top author citations in software engineering and a comparison with other fields

Ioannidis et al. provided a science-wide database of author citations. The data offers an opportunity to researchers in a field to compare the citation behavior of their field with others. In this paper, we conduct a systematic analysis of citations describing the situation in software engineering and compare it with the fields included in the data provided by Ioannidis et al. For comparison, we take the measures used by Ioannidis into consideration. We also report the top-scientists and investigate software engineering researchers’ activities in other fields. The data was obtained and provided by Ioannidis et al. based on the Scopus database. Our method for analysis focuses on descriptive statistics. We compared software engineering with other fields and reported demographic information for the top authors. The analysis was done without any modifications to the ranking. In the later analysis, we observed that 37% of researchers listed as software engineers were not in the software engineering field. On the other hand, the database included a large portion of top authors (ca. 60% to 80%) identified in other software engineering rankings. Other fields using the database are advised to review the author lists for their fields. Our research’s main risk was that researchers are listed that do not belong to our studied field.

Improved Analytical Method for Longitudinal Strain Analysis of Buried Pipelines Subjected to Thaw Slumping Load

Thawing landslide is a common geological disaster in permafrost regions, which seriously threatens the structural safety of oil and gas pipelines crossing permafrost regions. Most of the analytical methods have been used to calculate the longitudinal stress of buried pipelines. These analytical methods are subjected to slope-thaw slumping load, and the elastic characteristic of the soil in a nonlinear interaction behavior is ignored. Also, these methods have not considered the real boundary at both ends of the slope. This study set out to introduce an improved analytical method to accurately analyze the longitudinal strain characteristics of buried pipelines subjected to slope-thaw slumping load. In this regard, an iterative algorithm was based on an ideal elastoplastic model in the pipeline-soil interaction. Based on field monitoring and previous finite element results, the accuracy of the proposed method was validated. Besides, a parametric analysis was conducted to study the effects of wall thickness, internal pressure, ultimate soil resistance, and slope angle on the maximum longitudinal strain of the pipeline. The results from the compression section showed that the pipeline is more likely to yield, indicating an actual situation in engineering. Moreover, the maximum longitudinal tensile and compression strain of pipelines decrease with increasing the wall thickness, internal pressure, ultimate resistance of soil, and slope angle. Finally, based on the pipeline limit state equations in CSA Z662-2007 and CRES which considered the critical compression factor comprehensively, the critical slumping displacements for both tensile and compressive strain failures were derived for reference. The research results attach great significance to the safety of pipeline under slope.

Deformation Failure and Support Test of Surrounding Rock in Deep Arched Roadway with Straight Wall

The deformation and failure of the uphill roadway on the 3rd horizontal track in the No. 6 Mine of Pingdingshan Coal Group was taken as the engineering background. The similar simulation material of the roadway surrounding rock with quartz sand as the aggregate, cement as the cementing agent, and gypsum powder as the regulator was selected. Through mechanical tests on 25 sets of specimens with different proportions, the best proportion of similar simulated materials for simulating the deformation and failure of the surrounding rock of the roadway was obtained. Later, a large-scale deep mine roadway simulation test system independently developed by the company was used to carry out the roadway deformation and failure test. First, load the test body to the set initial stress state, and then carry out the full-face excavation and unloading of the roadway; finally, load it in the vertical direction until the roadway wall is damaged. It can realize the actual effect of simulation of roadway deformation and failure under the path of “high stress + internal unloading + stress adjustment.” The results showed that after the deep roadway is excavated with preload and high stress, the surrounding rock deformation, failure, and instability of the roadway mainly experience 3 periods: the first period is the period of uniform deformation of the roadway surrounding rock, the second period is the development period of the roadway surrounding rock slab structure, and the third period is the period of instability of the roadway surrounding rock slab structure. Combined with the time period of deformation and failure of the surrounding rock of the roadway, the damage scope of the surrounding rock and the actual situation of the site engineering. A step-by-step combined roadway repair and support plan of “bolt mesh + shotcrete + full-face hollow grouting anchor cable” with hollow grouting anchor cable as the core was determined. The stability of the repaired roadway has been significantly improved, ensuring the long-term use of the roadway.

On the Status Quo and Improvement Ways of Civil Engineering Teaching in China’s Colleges and Universities

With the gradual increase of civil engineering projects in our country, the demand for civil engineering talents from all walks of life is increasing, which effectively promotes the reasonable development and implementation of civil engineering talent training. Regarding this issue, under the promotion of educational reforms, Chinese educators have conducted in-depth analysis and investigations on the current development status of civil engineering teaching in colleges and universities, aiming to further realize the training and construction of civil engineering talents in colleges and universities, so as to help our country The reasonable satisfaction of civil engineering construction needs lays a solid foundation. This article discusses the current teaching situation of civil engineering in universities in my country, and proposes corresponding optimization suggestions, aiming to further improve the teaching quality of civil engineering in universities, so as to effectively meet the urgent demand for advanced talents in the civil engineering industry.

Target Situation in Vocational High School Civil Engineering Students’ Needs Analysis

Needs analysis for vocational high school English course is important because English course for vocational high school is considered too general compared to the target situation that the students will need in their future career. This study aimed to analyse the students’ teachers’, alumni’s, stakeholders’, and expert’s perceptions to explain the vocational high school civil engineering students’ needs in their English course. This study used a qualitative case design by using open questionnaires and in-depth interviews as the methods of collecting data. The findings showed that the main goal of the English course was to prepare the students to face the needs of English in their target situation. The learning approach needed was a scientific approach by using inquiry or discovery learning. The students needed more learning source which involved the target situation and a course which considered their current English proficiency. Finally, the students needed a course set that represented the target situation and teachers who were not only experts in pedagogical competence but also ESP. The results of the study can be used by the education practitioners to help them design better course for vocational high school civil engineering students.

Development of a bi-objective 0-1 mixed-integer nonlinear response surface-based robust design optimization model for unbalanced experimental data

The purpose of this paper is to develop a model to obtain the optimum operating conditions under special engineering situations. These special situations are: (1) both qualitative and quantitative input variables are considered, (2) a specific number of design points is required, (3) the experimental design space is irregular due to physical constraints, and (4) the unbalanced experimental data is collected due to resource limitations and focusing on certain treatment combinations. Although such situations may occur in many processes, there has been little research on this subject. To address these research gaps, first, an I-optimal experimental design is selected to construct a design matrix by using a modified exchange algorithm. Second, a weighted least squares method is presented to deal with the unbalanced experimental data. Third, a bi-objective 0-1 mixed-integer nonlinear programming-based robust design model and its solution procedures are proposed to obtain optimum settings of both qualitative and quantitative variables. Finally, a case study, along with the comparative study, is presented.

Complimentary Split Ring Resonator (CSRR) As A Viscometer For Engine Oils

A viscometer is a tool used to determine the strength of a fluid to shear or tensile stress. Meanwhile, engine oils are used to reduce friction and wear during operation and often deteriorate by the dynamic process with the combined effects of working conditions, contaminations and wear conditions. Therefore, the precise characterization of viscosity is important in the analysis of numerous engineering situations that consume engine oils that associate the functionality or performance of vehicles and machinery. This work aims to investigate the Complimentary Split Ring Resonator (CSRR) as a viscometer for engine oils. The antenna using radiation path such as CSRR is commonly used to measure the dielectric property of substances. Hence, this approach is applied to identify the dielectric properties of engine oils and establish the correlation between viscosity and dielectric properties. Eight engine oils from Shell were tested based on their margins in the terms of kinematic viscosity. Each oil was tested and repeated three times before the mean values were determined along with the frequency of 1-9GHz. The findings show no convincing and solid correlation between the two variables due to the small dielectric constant variation of engine oil with different viscosity. However, future works using current resonator will be applied in other applications associated with different material properties to build a predictive model. In addition, future work can consider sweeping in low frequency that might show positive results.

A new predictive model for normal and compound impact wear

This work presents a new model that predicts the wear that results from impacts occurring between two solid bodies under both normal and compound impact, a capability lacking from existing approaches. This frequently occurs in many engineering and industrial situations and depending on the relative sizes of the bodies, bulk material properties, and the number and frequency of impacts, damage can result. Although this eventually causes severe wear problems that limit service life, it is one of the least investigated types of primary wear mechanism. Due to this, robust data, and validated models derived from that data, are rare.The new model considers the contact with respect to shear force. It can predict wear volume loss and be used to improve understanding of the role of different impact angles during impact, and thus inform the design of machines, however it is currently valid for ductile materials only since hardness is a parameter. Empirical inputs to the model were developed using data produced specifically for this work. Predictions made by the model were then validated, with good correlation, for three common metal alloys by means of comparison with experimental data available in the literature.

Mechanism of colluvial landslide induction by rainfall and slope construction: A case study

The landslide hazards occurring in the complex geological genesis accumulation body are usually controlled by the coupling action of many internal and external factors. Therefore, this paper takes the dam-front Danbo accumulation body landslide of Yangfanggou hydropower station on the Yalong River as the geological prototype, and discusses the process and mechanism of slope stability degradation under the combined action of rainfall and slope construction. Based on the detailed understanding of the basic characteristics of the accumulation body, the development characteristics of the landslide and the construction situation of the slope engineering, the study conducted correlation analysis between rainfall and landslide displacement, the physical and mechanical tests of all types of rock-soil masses, and the numerical simulation testing of seepage field variation of the landslide section. It is found that the special slope structure and material composition of the old landslide accumulation layer on the upper part of the Danbo accumulation body are the internal factors for the occurrence of thrust load-induced landslide, and the construction of the slope engineering not only creates free space conditions for sliding, but also provides channels for the infiltration of rainfall into the slope after confluence, which is an external factor that caused the mechanical properties of the sliding zone soil to gradually weaken from the trailing edge to the leading edge. The geomechanical model of such landslide is that the active section of the trailing edge produces the “source of force”, the transition section of the middle section affects the occurrence of sliding, and the anti-sliding section of the leading edge controls the occurrence of landslide hazards. The results of this research provide not only a useful supplement to the theory of landslide formation mechanisms but also a scientific basis for guiding the prevention and control of similar hazards.

Thermal radiation, chemical reaction, Hall and ion slip effects on MHD oscillatory rotating flow of micro-polar liquid

The thermal radiation, chemical reaction, Hall and ion slip impacts on double-diffusive unsteady MHD natural convective rotating flow of micro-polar fluid past a semi-infinite vertical moving porous plate under the influence of uniform transverse magnetic field with convective boundary conditions have been investigated. The entire system is assumed to fluctuate in time with invariant frequency, therefore, the solutions of the boundary layer be of the oscillatory style. The non-dimensional governing equations are solved analytically through perturbation method and discussed computationally with references to pertinent parameters. It is observed that the velocity and micro-rotation profiles increases with an increase in Hall and ion slip parameters but reverse effects are found with an increasing in viscosity ratio and chemical reaction parameter. The thermal radiation parameter is to increase the temperature profiles but reverse effect is observed with an increasing in frequency of oscillations. Further, the concentration is decreased with increase in the Schmidt number and, it is increased with increase in the chemical reaction parameter. For engineering curiosity, the local skin friction and couple stress coefficients, rate of heat and mass transfer in terms of Nusselt number and Sherwood number are obtained analytically and discussed numerically. Although it is originated that, the local Nusselt number and local Sherwood number remains constant with varying all pertinent parameters. The heat and mass transfer on MHD flows through porous media with the chemical reaction arise in many transport processes both naturally and artificially in many branches of science and engineering applications. This phenomenon plays an important role in the chemical industry, power and cooling industry for drying, chemical vapour deposition on surfaces, cooling of nuclear reactors, and petroleum industries. The Hall and ion slip effects are used in many situations in bio-medical engineering and aero-space engineering.

A Multifidelity Aero-Thermal Design Approach for Secondary Air Systems

Abstract The paper presents a multidisciplinary approach for aero-thermal and heat transfer analysis for internal flows. The versatility and potential benefit offered by the approach are described through the application to a realistic low pressure turbine assembly. The computational method is based on a run time code-coupling architecture that allows mixed models and simulations to be integrated together for the prediction of the subsystem aero-thermal performance. In this specific application, the model is consisting of two rotor blades, the embedded vanes, the interstage cavity, and the solid parts. The geometry represents a real engine situation. The key element of the approach is the use of a fully modular coupling strategy that aims to combine (1) flexibility for design needs, (2) variable level of modeling for better accuracy, and (3) in memory code coupling for preserving computational efficiency in large system and subsystem simulations. For this particular example, Reynolds averaged Navier–Stokes (RANS) equations are solved for the fluid regions and thermal coupling is enforced with the metal (conjugate heat transfer, CHT). Fluid–fluid interfaces use mixing planes between the rotating parts while overlapping regions are exploited to link the cavity flow to the main annulus flow as well as in the cavity itself for mapping of the metal parts and leakages. Metal temperatures predicted by the simulation are compared to those retrieved from a thermal model of the engine, and the results are discussed with reference to the underlying flow physics.