Compendex

This work presents a comparative study of the surface mechanical properties and tribological wear resistance of polymeric sliding materials. The authors focused on the application of polymeric materials in producing spare parts for vehicles that are still in use but for which original components are no longer manufactured or are disproportionately expensive compared to the vehicle’s market value. The subject of the study was frictional interactions between the timing chain and the sliding element. Three commercial materials were tested, designated: PA6G, PA6G+MoS2, PE 1000. A commercial lubricant PMO 5W40 Extreme 100 % (intended for vehicles without a particulate filters) was used. The coefficient of friction and wear were analyzed under dry friction and oil bath. The lowest coefficient of dry friction was obtained for the PA6 G, whereas PE 1000 exhibits the highest. Under oil lubrication, however, PE 1000 demonstrated the lowest coefficient of friction. Microscopic analysis of wear scars was performed. The extent of wear depends on the type of material used and the nature of the interaction (dry friction, oil-bath friction). Wear under dry friction was lower than under oil-bath conditions, possibly due to the influence of the Rebinder effect.

This research focuses on the modeling and lateral control of an autonomous vehicle, employing a novel robust fixed-time sliding mode control method. Prior to any further analysis, a detailed model of the lateral dynamics of an autonomous vehicle is developed in order to accurately represent its nonlinear behavior and dynamic characteristics. Furthermore, a novel fixed-time sliding mode controller is employed to control the vehicle’s movement, effectively addressing nonlinearities while reducing the impact of uncertainties and external disturbances. This approach is known for its ability to provide a specific time of convergence, which results in achieving high accuracy and fast response. Subsequently, the stability of the overall system must be maintained by applying Lyapunov functions. In order to validate the effectiveness of the proposed control method, it is tested through simulations and compared with classical fixed-time sliding mode control and fixed-time fast terminal sliding mode control techniques. The results confirm the superior robustness and performance of the proposed control method, thereby highlighting its potential for autonomous vehicle applications.

The paper presents a method for controlling lateral movement with uncertain and unknown dynamics for an autonomous vehicle that combines the adaptive particle swarm optimisation (APSO) algorithm and the Lipschitz continuous sliding mode controller (LCSMC). Designing the desired trajectory, and modelling the vehicle using the bicycle model is the initial step. The control law is defined using the classical Lipschitz continuous sliding mode control (LCSMC) in the following step. In the next step, the system's nonlinear functions are modelled using a radial basis function neural network (RBFNN), the developed intelligent triangular observer is proposed, and the suggested approach adaptive Lipschitz continuous sliding mode control (ALCSMC) is suggested with stability analysis using the Lyapunov function and optimising the parameters gain using APSO algorithm after. Finally, the study is finished by simulating this strategy to see their performance and effectiveness in accomplishing the desired results.

The post-pandemic economic rebound has accelerated power demand. However, in a power generation system dominated thermal power plants, implementing the carbon peak strategy induces a contradiction between power supply and demand. This gives rise to the issues of the rational power allocation. To address this issue, based on enterprise micro-data, this study develops a model that allows power allocation across industrial enterprises to maximise their output. The ladder price is used for power redistribution seeking to ensure efficiency and fairness of the power allocation. Then, the utility theory is used to explore the effects of changes in the power use under different ladder prices. The paper relies on the unique dataset for Chinese enterprises. The results show that the proposed model renders power re-allocation among the enterprises (31 % of enterprises should reduce their power use, 32 % whereas should increase their power use by more than 50 %). By including the power cost in the model, significant differences were discovered between the optimal power use of three ladder price levels. This study provides recommendations for power allocation and the use of the ladder prices.

Sub-divisional errors (SDE) of linear encoders adversely affect mechanical equipment performance. Existing compensation methods often entail high costs or increased complexity. This research introduces an adaptive auto-compensation system for SDE reduction by minimize the factors of DC-offsets, deviation in amplitudes and phase disparities. The system has the advantage mitigate errors without significant additional expenses or complexity. Theoretical analysis of SDE and the experimental setup are discussed, alongside analytical data demonstrating the system's effectiveness.

This study investigates the mechanical properties of ceramic and photopolymer composites created using stereolithography (SLA) 3D printing. It aims to evaluate and compare the performance of two SLA materials: Liqcreate Composite-X and Phrozen's Water-Washable Resin, using dynamic flexural vibration tests to determine Young's modulus. Liqcreate Composite-X, a photopolymer resin with excellent mechanical properties, including high tensile and flexural strength, showed a first resonance frequency of 318 Hz and a Young's modulus of 0.93 x 1010 Pa. Phrozen's Water-Washable Resin, designed for easy post-processing, had a first resonance frequency of 210 Hz and a Young's modulus of 0.30 x 1010 Pa. In conclusion, Liqcreate Composite-X demonstrates superior mechanical performance, making it suitable for high-strength applications, while Phrozen's Water-Washable Resin, with lower mechanical properties, is more suited for less demanding uses. This study enhances the understanding and application of SLA-based ceramic composites in various engineering domains.

The paper discusses the design of functional observers with unknown inputs for nonlinear systems described by Takagi-Sugeno fuzzy models and time-varying bounded delays. The considered system extends previous works by considering a T-S model with time bounded delays and unknown inputs. The main innovative idea behind the design of the functional observer is that the unknown inputs are present in both the state and output equations, and bounds on the delays maybe used to reduce conservatism. The observer design and analysis are based on the Lyapunov-Krasovskii stability theory, and the resulting observer convergence conditions are formulated in terms of linear matrix inequalities (LMIs), which can be numerically and symbolically solved using YALMIP/MATLAB toolbox. In the final section of the paper, some examples are provided to demonstrate the application of this approach.

In construction projects, managers make multiple decisions every day. Most of these decisions are relatively unimportant; some of them are critical and could lead to the success or failure of a construction project. To ensure construction companies make effective managerial decisions, decision making requires performing an initial technical and economic analysis, comparing different decision-making solutions, using a planning system, and ensuring project implementation based on the provided plans. Therefore, the use of powerful systems such as business intelligence (BI), which play a central role in management and decision-making, is essential in project-based companies. The current study aims to determine and evaluate the main managerial opportunities in the application of BI in project-based construction companies using a descriptive survey approach. An empirical research questionnaire consisting of 60 factors and 7 categories was adopted. The questionnaire, after confirming its validity and reliability, was distributed to 100 experts engaged in 5 active project-based construction companies who were familiar with BI topics. To analyse the data, a one-sample t-test and the Friedman test were performed using the SPSS software. The findings indicated that the importance of the identified opportunities for the use of BI in project-based construction companies is above average and that, in the case of using BI in such companies, these opportunities can be used to improve project performance. The results of the current study can help managers and other stakeholders as an effective decision-making tool to better implement BI in project-based companies.

This study is devoted to the evaluation of the effect of natural polysaccharide (starch, alginate, and chitosan) solutions on the properties of clay composite. The authors describe the technology for obtaining gelated biopolymers (using hot and cold-water treatment and, acid treatment), as well as some characteristics of the obtained solutions, such as viscosity and pH. Some characteristics, such as bulk density, shrinkage, compressive strength, hygroscopic behavior, and water erosion resistance, are determined for the clay composites modified with biopolymer solutions. With increasing the concentration of biopolymer in solution, the bulk density and shrinkage values of the clay composite materials decrease. Also, the application of starch (2.5–10%) and alginate (2.5–7.5%) solutions has a positive effect on the compressive strength of the clay composite, with an increasing about 18–42%. Moreover, the addition of biopolymer solutions leads to an increase in the moisture adsorption degree of clay composites up to 34.2%. Finally, some biopolymers affect the structure and change the water erosion behaviour of clay composite.

The present work aims to study and compare the effect of incorporating argan nut shell (ANS) and wheat straw (WS) into clay mixtures as construction materials additives on physical, mechanical, structural, and thermal properties of fired clay bricks. Five clay mixtures were prepared, including a control sample free of waste, two clay samples containing 5 wt% and 10 w.t% of ANS (ANS5 and ANS10), two others containing 5 wt% and 10 wt% of WS (WS5 and WS10), all specimens were fired at 900 °C, and their technological properties in term of loss on ignition, firing shrinkage, water absorption, apparent porosity, bulk density, flexural strength, compressive strength, and thermal conductivity were evaluated. A reduction in bulk density and thermal conductivity has been observed with the incorporation of ANS and WS, leading to an increment in the apparent porosity and water absorption in their turn, which is typically due to the specimen’s porous structure. The thermal conductivity of clay brick samples containing 5–10 wt% of ANS or WS decreased by 5–17% and 27–46%, respectively. Thus, the thermal insulation property is improved while the mechanical properties (flexural and compressive strength) meet the requirements of the standards for clay masonry units, except for WS5 brick. Test results highlighted the potential of recycling ANS and WS in clay masonry units and thus, the production of lightweight material.