Experimental Analysis Methods Research Articles

Experimental research on creep characteristics and failure mechanism of mining roadway in nearly vertical coal seams

Introduction: Nearly vertical coal seams present a significant challenge for the coal mining industry due to their difficult accessibility. However, these seams account for a substantial proportion of the world’s coal reserves. Therefore, it is vital to conduct research on disaster control techniques for safe mining of these seams.Method: The research team used experimental research, theoretical analysis, and numerical calculation methods to investigate the creep characteristics and failure mechanisms of layered sandstone roadway in nearly vertical coal seam.Results and discussion: These findings revealed that the maximum moment and concentrated stress of the sandstone located on the side of the roadway roof was positioned in the middle of the nearly vertical structure, making it more susceptible to transverse shear failure. On the other hand, the nearly vertical structure on the floor side was prone to shear slip failure initiated from the bottom of the structure. This led to the asymmetric instability of the roadway. The practical implications of this research are significant for the safe mining of nearly vertical coal seams. The results could help inform the development of disaster control techniques.

Study and Design of Corrugated Cardboard Trays With Microwaves by Experimental Analysis (EA) and Finite Element Methods (FEM)

ABSTRACTThe purpose of the work is to study by experimental analysis and finite element methods the mechanical response of a packaging, consisting of a corrugated cardboard container, used for the transport of fruit and vegetables. During the container design, three different configurations were selected which differ both in the choice of liner and in the type of wave. In particular, the type E, F and N microwaves were chosen. They are characterized by a lower amplitude than the high and medium waves commonly used in corrugated cardboard packaging, making it possible to reduce material consumption and, consequently, costs. In the initial phase of the study, experimental tests were performed to evaluate the mechanical strength of the liners. In addition, edge compression tests (ECTs) were performed to determine the stacking resistance of the structure. The break‐in resistance of the structures was analysed using a test conducted according to an internal standard, called strength packaging test (SPT). Subsequently, a parametric study was set up with the finite element method for the simulation of the mechanical behaviour of the three structures, using the homogenization technique. The comparison between the maximum total deformations, measured experimentally and calculated numerically, has highlighted the need to introduce corrective coefficients to improve the homogenization of the wave structure. In this way, it was possible to improve the matching of the results obtained on the structures simulated by the homogenization technique and those obtained on the corresponding real structures.

Ignition energy, explosion flame propagation, and particle movement process of coal dust cloud in vertical Hartmann tube

To discuss the ignition energy, explosion flame propagation, and particle movement process of coal dust in vertical glass tube, experimental analysis and numerical simulation methods are used to carry out research. The experimental research results show that the optimal ignition delay time is 1 s, under this condition, the dust cloud near the ignition electrode has the highest turbulence, making it easier to ignite. When the dust cloud mass concentration is 2500 g/m3, the ignition energy is the smallest, resulting in the highest risk of explosion. The simulation results show that the propagation speed of flame is 4 m/s, due to the small amount of suspended dust used, the intensity of the explosion is not significant. The further away from the explosion source, the more energy is lost, the lower the temperature of the flame. Within 30∼50 ms after the ignition, the temperature near the explosion source rapidly increases, from 900 K to 1300 K. During the period of 0.2–0.5 s after dust injection, most particles move upwards along the tube. At 1 s after the dust injection, most particles move downwards and gather near the ignition electrode, forming a suspended dust cloud that is easily ignited, which is consistent with the optimal ignition delay time of 1 s obtained from the experiment.

Optimization and Analysis of Clutch Switching Timing for Hybrid Tractors Equipped with Hydraulic Mechanical Combined Transmission

The working environment of tractors is harsh and the working conditions are very complicated. To cope with this complex and changeable working environment, this paper presents a hybrid tractor powertrain loaded with hydraulic mechanical combined transmission (HMCVT). The powertrain can switch modes according to different operating environments. During mode switching, impact loads can cause wear and even damage to the transmission components. Interrupting the power transmission will reduce the tractor’s operational efficiency. In this paper, the orthogonal experimental range analysis method was proposed to optimize the quality of mode switching. Mode switching involves interactions between clutches. Orthogonal table L16 (215) was selected to design the orthogonal table head. SimulationX was used for simulation. Employing MINITAB range analysis yielded the optimal results. The simulations indicated a reduction in the output shaft’s velocity drop amplitude from 17.647% to 6.591%. The dynamic load coefficient decreased from 2.743 to 1.857. The impact strength was reduced from 14.125 to 5.67 m/s3. The switching time was reduced from 2.13 to 1.71 s. We built a model-in-the-loop (MIL) test platform to validate the results. The MIL test results were compared with the simulation results. Our findings indicate a degree of discrepancy between the simulated and the experimental results, yet the overall trends remain largely consistent. The correctness of the optimal scheme obtained from the orthogonal experiment is verified. This study provides a theoretical basis for the optimization of powertrain mode switching in hybrid tractors equipped with HMCVT.

Physicochemical And Organoleptic Quality Testing Of Millet Microgreen Juice (Panicum Miliaceum L.) On Different Milet Types And Plant Age

This research has taken place using experimental laboratory methods of quantitative analysis. The variables used include varieties consisting of yellow millet and red millet, and plant life ranging from 6 days, 9 days, 12 days, and 15 days. The data obtained was analyzed based on parametric statistics using ANSIRA, using statistical product and service solution (SPSS) with version 24 and determining best treatment using effectiveness tests and determining antioxidant levels of best treatment. Different types and ages of plants have very real effects on reduced sugars, phenols, vitamin C, flavonoids and total soluble solids. Significant treatment between different plant types and ages resulted in a 6-day-old ryellow millet (MG1) being the best treatment with a result value (NH) of 0.73 with the parameter criterion reduction sugar level of 1.48%, total phenol content of 27.26 mg GAE/100mg, vitamin C 2.05 mg/100 mg, total flavonoid content of 4.98 mg QE/100 Mg, TPT 11.36 mg/L, color 4.81 (neutral), flavor 5.16 (few likes) and aroma 5.4 (few likes).

On the Question of Admissibility of Certain Methods in Forensic Linguistic Examination

The article raises the question of the criteria of admissibility of the use of certain methods in forensic linguistic examination. Despite the methodology of forensic linguistic examination that has been worked out over the years, some specialists prefer to use extremely controversial methods, for example, such as the method of associative experiment and phonosemantic analysis. These methods do not meet the criteria required by forensic expertology, which leads to the expert exceeding the limits of his/her competence, as well as to serious expert mistakes.

Seismic performance evaluation of precast post-tensioned high-performance concrete frame beam-column joint under cyclic loading

Precast concrete structures have developed rapidly because they meet the requirements of green and low-carbon social development. In this paper, a precast post-tensioned high-performance concrete frame beam-column joint was proposed, and the low-cycle reversed load test was performed on the four proposed joints. The main differences between the four joints are the different prestress values applied by the joints and whether the beam-column joint is provided with L-shaped steel. The seismic performance indexes such as hysteresis curve, stiffness degradation, deformation capacity, energy dissipation capacity and residual deformation of each node were obtained through experiments. By comparing various seismic performance indicators, it could be found that the use of high-performance concrete could effectively avoid the phenomenon of local crushing of concrete due to excessive prestressing. At the same time, it was found that the setting of L-shaped steel plate at the beam-column junction could effectively avoid the early damage at the beam-column junction. On the basis of the test, the three-line restoring force model of the joint was established by the method of experimental regression analysis. The model could better reflect the stress situation of each stage of the joint. Based on the experimental and theoretical analysis, the finite element analysis model of the joint was established, and the model calculation results were in good agreement with the experimental results.

Introduction of practice-oriented learning in the training of future teachers

Relevance. The relevance of the study is conditioned by the modernisation of the modern higher education system, specifically, by the need to apply effective teaching methods for training polyfunctional pedagogical specialists. Purpose. The purpose of this study was to find best methods and techniques of training future teachers in the context of forming their interest in learning and mastering practical skills in the context of modern requirements to a pedagogical specialist. Methodology. The conceptual framework of the theoretical and methodological approach to the research problem was a qualitative combination of the methods of content analysis, synthesis, and deduction, as well as the methods of experimental learning, observation, and comparative analysis. Results. The analysis of theoretical foundations on the research topic showed that practice-oriented learning is based on the principles that emphasise the practical application of knowledge, development of skills and competences necessary for successful professional activity of a specialist. The analysed modern scientific works allowed highlighting the relevant problems of the introducing practice-oriented learning in higher education, which contributed to the development and implementation of the concept of increasing the interest of future teachers in mastering professional skills in the educational process. The conducted pedagogical experiment revealed substantial differences in the use of conventional teaching methods and the selected strategy in the context of development of students� professional competences. Conclusions. It was empirically established that practice-oriented forms of class organisation allow creating conditions for active learning activities of students, which also affects their adaptation to the performance of professional tasks and motivation to the implementation of pedagogical activity in general. The value of the obtained research results lies in the developed approach of integrating the case study method into the educational programme, which allows optimising the implementation of practice-oriented learning for students of pedagogical specialities. Keywords: higher education; case study; pedagogical skills; professional competences; motivation; learning activity

Nitrogen recycling characteristics in multiphase transformation during municipal sludge pyrolysis

The nitrogen content of municipal sludge is as high as 2.5～9.0 wt%, which has become an important problem in pollution control during pyrolysis. Recycling nitrogen from municipal sludge not only enables resource utilization, but also reduces the nitrogen-related pollution. In this study, the transformation pathways of nitrogen to resource material and typical pollutants during the municipal sludge pyrolysis process were analyzed. The results showed that the nitrogen species in municipal sludge were mainly protein-N (64.41%), pyridine-N (19.47%) and inorganic-N (16.13%). After pyrolysis at 300 °C, the peptide bond of protein-N was gradually broken down, resulting in the formation of three nitrogenous intermediates (amine-N, nitrile-N and heterocyclic-N) were produced. These intermediates can be transformed to NH3 for resource recovery or to HCN pollutants. Moreover, the full nitrogen transformation pathways of municipal sludge pyrolysis were constructed by the method of Spearman's correlation coefficient and experiment analysis. It was found that NH3 and HCN were mostly generated from the cracking of three nitrogenous intermediates at 600–800 °C. In addition, there was a prominent effect on the transformation of HCN to NH3 with co-presence of calcium minerals in raw sludge. By adding inorganic calcium minerals, NH3 as a recyclable component was prominently improved by 10.30% at 700 °C, while HCN yield was decreased by 53.02% accordingly under the inhibitory effect. The results systematically provided a theoretical support to the possibility of nitrogen recycling for utilization during municipal sludge pyrolysis, as well as to control the transformation of nitrogen elements into pollutants.

CFD and Wind Tunnel Study on Cricket Ball at Different Seam Angle and Velocity

This study delves into the intriguing investigation of flow patterns over a cricket ball, employing both computational and experimental methods for a comparative analysis. The work explores about variation of velocities in different angles, here we have used as 4 cricket balls they are dukes cricket balls, SG cricket balls, dukes 3d printed cricket ball and SG printed cricket ball. While comparing all the cricket balls it shows values in the wind tunnel experiment in seam angles of 0°,30°,45°,60°& 90° in a subsonic wind tunnel. Both computational simulations and experimental observations were conducted to analyze the impact of seam angles and velocities on the cricket balls. The results obtained from computational models were successfully validated through experimental data, affirming the reliability of the computational approach in predicting aerodynamic characteristics. Flow visualization techniques further confirm these findings, highlighting the significance of keywords such as drag, seam angles, reverse swing, flow visualization, and computational fluid dynamics (CFD) in understanding the aerodynamics of cricket balls. Overall, this research provides valuable insights into optimizing bowling strategies by considering the interaction between seam angles, velocities, and aerodynamic behavior of cricket balls. Keyword: Ball drag analysis, Reverse swing analysis, CFD analysis, Cricket ball analysis.

Experimental and numerical study on mechanical behavior of 3D printed adhesive joints with polycarbonate substrates

AbstractAdhesive joints play a crucial role in enhancing the structural integrity and performance of 3D printed parts. The purpose of this study is to investigate the failure load and behavior of polycarbonate (PC) single lap joints (SLJs) produced by fused deposition modeling (FDM) using experimental and finite element analysis (FEA) methods. The FEA of joints presents a new approach by integrating PC substrates with Hill yield criterion, transversely isotropic material and adhesive layer with cohesive zone modeling (CZM). The study focused on the effect of printing angles (0°, 45°, and 90°) and overlap lengths (12.5 and 25 mm) on the performance of SLJs. The influence of 3D printing parameters on the mechanical behavior of PC joints was investigated by tensile testing of SLJs. The experimental failure load was 1586 N for a 12.5 mm joint at 90° and 4115 N for a 25.4 mm joint at 0°. Comparison of the experimental and FEA failure loads of the joints showed maximum and minimum differences of 11.98% and 1.34%, respectively. This result showed that the proposed model is applicable for determining the joint strength as a function of the printing angle and monitoring the joint damage behavior.

Launch Dynamics Analysis of Amphibious Launch Vehicle on the Sea

Due to its agility, concealment and excellent amphibious combat capability, amphibious vehicles can perform tasks in complex terrain and environment, and have important application value in the field of national defense and people ’s livelihood. In this paper, the method of experimental data-driven numerical simulation analysis is used, combined with batch simulation technology, and the frequency histogram in probability statistics is used to study the launch safety of amphibious vehicles under random waves, and the influence of missile launch sequence and launch time interval on missile launch is explored. The results show that the driving and sea launch of the amphibious vehicle are safe under the experimental conditions. The partial attitude angle of the car body and the attitude angle of the missile roughly conform to the normal distribution; considering the relationship between the weight of the vehicle body and the ejection load impulse, the launch sequence and the launch time interval will not have a great impact on the missile launch. By evaluating the driving safety of the amphibious vehicle and the launch safety of the missile, this paper can provide some theoretical significance and engineering application value for the sea launch of the amphibious vehicle.

Research on Fe Removal, Regeneration Process, and Mechanical Properties of Mg Alloy AM50A

In recent years, the widespread application of Mg alloy casting and Mg alloy products has generated a large amount of Mg alloy waste. This experiment used a single factor experimental analysis method to study the optimal process for removing Fe from Mg alloy AM50A waste, and developed an efficient Fe removal and regeneration process for Mg alloy AM50A. It was found that the optimal refining temperature for removing Fe ions was 670 °C, the optimal refining (RJ-2) agent mass ratio was 1.5%, and the optimal refining time was 40 min. Regenerated J40-1.5-AM50A Mg alloy was prepared using the best refining process, and its composition and mechanical properties were tested and analyzed. The experimental results show that the composition of the regenerated J40-1.5-AM50A Mg alloy prepared by this method is consistent with AM50A, with an Fe removal rate of 96.2%. The mechanical properties were improved compared to the original AM50A sample, with a maximum tensile strength increase of 1.611 KN and a tensile strength increase of 26.333 MPa. The elongation after fracture is 2.25 times that of the original sample. Research has shown that the RJ-2 refining agent can provide mechanical properties of magnesium alloys during the refining process. By analyzing the composition, XRD, SEM, and EDS of AM50A (Fe) and J40-1.5-AM50A, it was found that the refining process accelerates the removal of Fe in the form of Fe deposition.

Novel hybrid chemical magnetorheological fluid for polishing Ti–6Al–4V alloy

ABSTRACT This study presents a highly efficient chemical and magnetorheological fluid (C-MRF) hybrid polishing process established by using an eco-friendly slurry of malic acid, Fe3O4–SiO2 abrasive particles, and hydrogen peroxide (H2O2) as an oxidant, all mixed with purified water, highlighting its efficacy in a wide range of polishing applications. Herein, the polishing processes of Ti–6Al–4V alloy utilizing C-MRF with on Fe3O4–SiO2 abrasives are detailed, and the polishing performance is assessed by investigating the influence of oxidizing agent H2O2 and acid malic to the surface finish of the Ti–6Al–4V alloy. The linear variable magnetic field by improved Halbach array was proposed to improve the material removal rate and surface quality and create a polishing process with a highly efficient magnetic field source. Single-factor and orthogonal experimental analysis methods are applied to provide the technological parameters factors with varying influences on surface quality and material removal ability.

Fiber-reinforced friction materials: Experimental, statistical and computational universal analysis

In this paper, the experimental, statistical and computational universal analysis methods applicable to most fiber-reinforced friction materials (FMs) are presented for four natural wollastonite fibers (WFs) with different length-to-diameter (L/D) ratios. Machine learning (ML) methods for friction coefficient prediction of friction materials are compared and screened. Numerical statistics and calculations are used in conjunction with the use of finite element (FE) models to determine the performance metrics and friction wear mechanisms of FMs. The experimental and computational results show that the artificial neural network (ANN) model performs the best in COF prediction with an accuracy of 0.961. The friction fluctuation, friction stability and integrated friction performance of the WF-containing samples are better than those of the blank samples. For the first time, the FE model was used to explain the swirling phenomenon on the wear surface of FMs. This study provides new ways and ideas for the design, experimentation, data processing and application of friction composites.

A Comparative Study on the Operational Efficiency of Joystick and Touch Screen Control Methods for Sugarcane Harvesters

Reducing cumbersome mechanical control components is one of the trends of modern agricultural machinery towards a high degree of automation. Whether the control components of sugarcane harvesters can gradually be replaced by central control screens, similar to car cabins, is an unresolved question. At the level of human machine interaction, this involves comparing the efficiency between joystick and touch screen control. This paper conducts a simulated experiment to compare and study the efficiency and user experience of joystick and touch screen control in adjusting the topper and base cutter heights of sugarcane harvesters, aiming to provide a reasonable basis for the design of control interfaces in sugarcane harvester cabins. The electromyographic signals, experiment duration, and subjective cognitive evaluations of participants in both the topper and base cutter groups were analyzed. The results showed that the efficiency, learnability, and ease of use of different control methods varied under different operational tasks. For the topper that corresponds to the operating behavior and height transformation in real time, joystick control demonstrated superior ease of use and operational efficiency compared to touch screen control, with weaker learnability. There was no discernible difference in muscle activation levels between the two control methods. Consequently, joystick control is deemed more suitable for the height adjustment of the topper. Regarding the base cutter with non-real-time mapping of operating behavior and height changes, no significant disparity in ease of use and learnability was observed between the two control methods. Touch screen control yielded lower muscle activation levels and garners higher overall subjective cognitive scale ratings. Thus, touch screen control is considered more suitable for base cutter height adjustment. Lastly, the paper proposes the optimal combination of software and hardware for control components in sugarcane harvester cabins, and provides an objective and multidimensional experimental analysis method for future research on similar human machine interaction interfaces.

The impact of inquiry-based laboratories on improving pre-service teachers’ experimental competency

In this article, we analyze how IBL affects the experimental competency of pre-service physics teachers. An experimental quantitative analysis method, the static-group pretest-posttest design, has been utilized. A total of 32 pre-service physics teachers participated in the experimental group. In order to observe the experimental competency development level of pre-service physics teachers, the PLIC test and experimental competency test have been used. The findings revealed that inquiry-based laboratories are remarkably effective in developing pre-service physics teachers' experimental competency. The growth rate of behavioral indicators is relatively uniform except for two behaviors (2.7) and (4.5). In addition, the development of pre-service teachers’ experimental competency has reached a high level, but the percentage of students reaching level 3 is still low (14.63%). Therefore, it is suggested that further research, which focuses on increasing the support of teachers at level 3 and expanding the sample size, is needed.

Nematicidal glycosylated resorcylic acid lactones from the fungus Pochonia chlamydosporia PC-170 and their key biosynthetic genes.

Chemical study of the nematicidal biocontrol fungus Pochonia chlamydosporia PC-170 led to discovery of six resorcylic acid lactones (RALs), including three nematicidal glycosylated RALs, monocillin VI glycoside (1), colletogloeolactone A (2) and monocillin II glycoside (3), and three antibacterial non-glycosylated RALs, monocillin VI (4), monocillin IV (5) and monocillin II (6). The planar structure of the new compound monocillin VI glycoside (1) was elucidated using HRESIMS and NMR data, and its monosaccharide configuration was further determined through sugar hydrolysis experiment and GC-MS analysis method. Furthermore, their two biosynthetic-related PKS genes, pchE and pchI, were identified through the gene knockout experiment. The glycosylated RALs 1-3 exhibited nematicidal activity against Meloidogyne incognita, with LC50 values of 94, 152 and 64 μg/mL, respectively, and thus had great potential in the development of new nematicidal natural products to control M. incognita in the future.

Flexural Behavior of Inverted Steel Fiber-Reinforced Concrete T-Beams Reinforced with High-Yield Steel Bars

This study discusses the effectiveness of T-beams reinforced with steel fibers and 600 MPa longitudinal reinforcements on negative flexural responses based on experimental and finite element analysis (FEA) methods. Four T-beams reinforced with 400 MPa or 600 MPa reinforcements were manufactured and inversely loaded. Two of the beams were fabricated with 0.75% (by volume) steel fibers as per JGJ/T465-2019, while the rest were cast following the same design but without steel fibers for comparison. The failure modes, the cracking moment and width, and the stress of the longitudinal reinforcements and concrete were compared between the four tested T-beams. In particular, deflection–load curves indicated the improved flexural ability of the specimens with steel fibers and high-yield steel bars. Models of T-beams with longitudinal reinforcements measuring 6, 8, and 12 mm in diameter were simulated and compared with the results of validated models. The FEA results further demonstrate the better flexural performance of T-beams reinforced with steel fibers and longitudinal reinforcements. Both materials can increase the overall performance of inverted steel fiber-reinforced concrete T-beams, including cracking load, crack width, ultimate load, and deflection. However, the findings showed that different diameters of longitudinal reinforcements generated different levels of effectiveness.

Optimization of inclined coal seam tunnel section angle and anchor angle based on response surface method

The mining of inclined coal seams is often accompanied by problems such as difficult to control deformation of the tunnel roof and failure of anchor bolts. Taking the transportation channel of Jinping Coal Industry 1071-1 in Shanxi Xiangkuang Mine as the background, FLAC3D numerical simulation software was used, and the method of response surface experimental design and data analysis was used to systematically study the effects of the anchor installation angle and the roof inclination angle of the tunnel section on different inclination angles. Influence of the surrounding rock stability of coal seam roadways. On this basis, a multi-index tunnel support design evaluation method based on the response surface method was proposed, and the actual support plan was optimized and industrial tests were carried out based on the actual on-site support plan. The research results show that: in terms of inclined coal seam support, the degree of influence on the tunnel stability is in the following order: anchor installation angle > tunnel section roof inclination angle > coal seam inclination angle; the optimized support design obtained through the proposed technology The method has good application effect and can improve the stability of the roadway during the mining of the working face. It also proves the effectiveness of this technology and provides new ideas for the design of anchor support of inclined coal seam roadways and the optimization of roadway sections.