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Most existing studies about line balancing problems mainly focus on disassembly and assembly separately, which rarely integrate these two modes into a system. However, as critical activities in the remanufacturing field, assembly and disassembly share many similarities, such as working tools and processing sequence. Thus, this paper proposes a multi-objective hybrid production line balancing problem with a fixed number of workstations (HPLBP-FNW) considering disassembly and assembly to optimise cycle time, total cost, and workload smoothness simultaneously. And a novel Pareto-based hybrid genetic simulated annealing algorithm (PB-HGSA) is designed to solve it. In PB-HGSA, the two-point crossover and hybrid mutation operator are proposed to produce potential non-dominated solutions (NDSs). Then, a local search method based on a parallel simulated annealing algorithm is designed for providing a depth search around the NDSs to balance the global and local search ability. Numerical results by comparing PB-HGSA with the well-known algorithms verify the effectiveness of PB-HGSA in solving HPLBP-FNW. Moreover, the managerial insights based on a case study are given to inspire enterprise companies to consider hybrid production line in the remanufacturing process, which is beneficial to reduce the cycle time and total cost and improve the service life of the equipment. [ABSTRACT FROM AUTHOR]

VO2-based thermochromic coatings have gained much attention in temperature-adaptive smart windows, and constructing multilayer film structures is the main way to obtain high thermochromic performances. Based on the self-developed objective-orientated automatic optimization code, the present research realized customized designs of thermochromic multilayer coatings composed of VO2, TiO2, and SiO2 from the objectives of visible luminance (Tlum) and solar light modulation (ΔTsol). The TiO2/VO2/s, VO2/TiO2/s, TiO2/VO2/TiO2/s, and SiO2/TiO2/VO2/TiO2/s (s denotes substrate) multilayer film systems were then prepared by magnetron sputtering and vacuum controllable heating, with their structures, insulator-metallic transition, and thermochromic properties being carefully studied. The result showed that the best trade-off between high Tlum and high ΔTsol was achieved for these film assemblies, and solar light modulation was mainly limited at the near-IR wavelength region of the solar spectrum, with the difference between cool- and hot-state Tlum being greatly reduced. In the case of the four-layer SiO2/TiO2/VO2/TiO2/s, very high average Tlum (60%) and high ΔTsol (14%) were obtained. A 100 × 100 mm2 of the SiO2/TiO2/VO2/TiO2/s was also prepared, and it showed an obvious temperature adjustment, and the service life can last for 14 years under normal weather conditions. Not limited to the prepared multilayer film systems, the methodology used here is also suitable for the fast development of other multilayer film systems. [ABSTRACT FROM AUTHOR]

This paper reports a flexible glucose biosensor which is modified by a reduced-swelling and conductive zwitterionic hydrogel enzyme membrane that contains two forms of chemical cross-links. One chemical cross-linking is induced by thermal initiators and forms the basal network of the hydrogel. Another cross-linking is achieved by the coordination interactions between the multivalent metal ion Al3+ and anionic group -COO− of zwitterionic poly-carboxy betaine (pCBMA), which significantly increase the cross-linking density of the zwitterionic hydrogel, improving the reduced-swelling property and reducing the pore size. The better reduced-swelling property and reduced diameters of pores within the zwitterionic hydrogel make less glucose oxidase (GOx) leakage, thus significantly improving the enzyme membrane's service life. By introducing the Al3+ and Cl−, the conductivity of the zwitterionic hydrogel is enhanced approximately 10.4-fold. According to the enhanced conductivity, the reduced-swelling property, and the high GOx loading capacity of the zwitterionic hydrogel, the sensitivity of the biosensor with GOx/pCBMA-Al3+ is significantly improved by 5 times and has a long service life. Finally, the proposed GOx/pCBMA-Al3+ biosensor was applied in non-invasive blood glucose detection on the human body, verifying the capability in practice. [ABSTRACT FROM AUTHOR]

Polymeric applications with extended service life and low energy loss due to friction are of great interest in conveyor and power transmission technology. Self‐lubricating systems utilizing microcapsules hold significant potential for increasing energy efficiency and extending the operational life of these applications. This study focuses on synthesizing oil‐filled microcapsules through in situ polymerization of polyamide and their incorporation in polyamide 6 and polyamide 6.6. Microcapsules with a core made of thermally stable lubricant Food Lube, and particle diameter D90 of 50 μm were synthesized and isolated as a free‐flowing powder via spray‐drying procedure. The resulting powder demonstrated high thermal stability (loss of 5% at 350°C) due to the high thermal stability of both core and shell materials. A compounding process utilizing a twin‐screw extruder was developed to blend microcapsules into thermoplastic matrices. An injection molding machine forms tension rods. The composites' tribological properties are assessed through ball‐on‐disc tests conducted in both oscillation and rotation. The friction coefficient and wear rate of the composites experience a reduction of 79% and 56% for polyamide 6, as well as 77% and 75% for polyamide 6.6. Mechanical testing of the microcapsule composites reveals a decrease in mechanical properties. [ABSTRACT FROM AUTHOR]

Owing to the architected void-filled low-density configurations, metamaterials are prone to defects during the complex manufacturing process, or damages under operational conditions. Recently mechanical cloaking has been proposed to shield the effect of such disorders in terms of homogenized mechanical responses. The major drawback in these studies are that the damage location should be known a priori, and the cloak is designed around that damaged zone before manufacturing. Such postulation does not allow unsupervised damage resilience during the manufacturing and service life of metamaterials by active reconfiguration of the stress field depending on the random and unpredictable evolution of damage. Here, we propose a radically different approach by introducing piezoelectric lattices where the effect of random appearance of any single or multiple disorders and damages with complex shapes, sizes and distributions can be shielded through active multi-physically controlled cloaks by voltage-dependent modulation of the stress fields within the cloaking region. Notably, this can be achieved without breaking periodicity and any additional material in the cloaking region unlike earlier studies concerning mechanical cloaks. The proposed active class of elastic metamaterials will bring a step-change in the on-demand mechanical performance of critically important structural components and unsupervised damage resilience for enhanced durability and sustainability. This article is part of the theme issue 'Current developments in elastic and acoustic metamaterials science (Part 1)'. [ABSTRACT FROM AUTHOR]

Bridges enable communications and transportation of goods nationally and internationally, underpinning economic and social activities, and thus they are pylons of our prosperity and mobility. Bridges worldwide are constantly subjected to physical wear, ageing, deterioration, hazards, environmental influences, and increased loading. Loss of performance and functionality of bridge structures would have a crucial impact on overall infrastructural resilience and would cause significant negative economic and social consequences. Monitoring their behaviour for different loading conditions relies on accurate estimations of the stress‐strain state of various critical components and remaining capacities. These activities are of high importance for better planning and lifespan prolongation, that is, the extension of their service life and prevention of unforeseen collapses, in line with sustainability principles of well‐informed maintenance. In many cases, access to the structure is limited or even impossible, which causes the need for the deployment of remote and contactless methods. One such innovative technique, which has recently attracted attention in scientific and practical applications, is the digital image correlation (DIC). DIC is a contactless approach applicable for obtaining the full field of strains and deformations of full‐scale real structures. Although the DIC approach has been widely used in world engineering practice for monitoring bridges and has proved to be a reliable and accurate method, there is a lack of systematic integral review on previous practical applications, revealing limitations and perspectives. This is the main motivation and novelty of this study, which will describe selected case studies in which DIC was used on real full‐scale bridge structures and propose improvements for the method. [ABSTRACT FROM AUTHOR]

An understanding of the mechanical behavior of polymeric materials is crucial for making advancements in the applications and efficiency of nanocomposites, and encompasses their service life, load resistance, and overall reliability. The present study focused on the prediction of the mechanical behavior of biopolymeric nanocomposites with nano-clays as the nanoadditives, using a new modeling and simulation method based on Comsol Multiphysics software 6.1. This modeling considered the complex case of flake-shaped nano-clay additives that could form aggregates along the polymeric matrix, varying the nanoadditive thickness, and consequently affecting the resulting mechanical properties of the polymeric nanocomposite. The polymeric matrix investigated was biopolyamide 11 (BIOPA11). Several BIOPA11 samples reinforced with three different contents of nano-clays (0, 3, and 10 wt%), and with three different nano-clay dispersion grades (employing three different extrusion screw configurations) were obtained by the compounding extrusion process. The mechanical behavior of these samples was studied by the experimental tensile test. The experimental results indicate an enhancement of Young's modulus as the nano-clay content was increased from 0 to 10 wt% for the same dispersion grades. In addition, the Young's modulus value increased when the dispersion rate of the nano-clays was improved, showing the highest increase of around 93% for the nanocomposite with 10 wt% nano-clay. A comparison of the modeled mechanical properties and the experimental measurements values was performed to validate the modeling results. The simulated results fit well with the experimental values of Young's modulus. [ABSTRACT FROM AUTHOR]

Technological equipment in quarries that extract and deliver aggregates for different uses operates in a predetermined flow depending on the type of rocks exploited and the dimensional characteristics imposed on the final products. In this context, the interruptions in operation required to replace high-wear parts (such as the teeth of excavators and bucket loaders) must be limited as much as possible through technological solutions to increase their service life. The evolution of the wear of the teeth of the quarry equipment that come into direct contact with rocks was concretely established in the production process, in parallel with the wear values obtained by simulating the wear phenomenon in laboratory conditions, in order to validate the data collected during the operation of the machines. Preventive–repetitive maintenance within the activities of reconditioning the worn surfaces of the teeth, through the charging process by manual electric welding with covered electrodes, was applied directly to the machine, which led to the shortening of the interruptions in operation necessary to replace these spare parts. [ABSTRACT FROM AUTHOR]

To comprehensively understand the impact of various environmental factors on the self-healing process of graphene-modified asphalt, this study employs molecular dynamics simulation methods to investigate the effects of aging degree (unaged, short-term aged, long-term aged), asphalt type (base asphalt, graphene-modified asphalt), healing temperature (20 °C, 25 °C, 30 °C), and damage degree (5 Å, 10 Å, 15 Å) on the self-healing performance of asphalt. The validity of the established asphalt molecular models was verified based on four physical quantities: density, radial distribution function analysis, glass transition temperature, and cohesive energy density. The simulated healing time for the asphalt crack model was set to 200 ps. The following conclusions were drawn based on the changes in density, mean square displacement, and diffusion coefficient during the simulated healing process under different influencing factors: Dehydrogenation and oxidation of asphalt molecules during the aging process hinder molecular migration within the asphalt crack model, resulting in poorer self-healing performance. As the service life increases, the decline in the healing performance of graphene-modified asphalt is slower than that of base asphalt, indicating that graphene-modified asphalt has stronger anti-aging properties. When the vacuum layer in the asphalt crack model is small, the changes in the diffusion coefficient are less pronounced. As the crack width increases, the influence of various factors on the diffusion coefficient of the asphalt crack model becomes more significant. When the crack width is large, the self-healing effect of asphalt is more dependent on these influencing factors. Damage degree and oxidative aging have a more significant impact on the healing ability of graphene-modified asphalt than healing temperature. [ABSTRACT FROM AUTHOR]

Conventional asphalt roads are noisy. Currently, there are two main types of mainstream noise-reducing pavements: pore acoustic absorption and damping noise reduction. However, a single noise reduction method has limited noise reduction capability, and porous noise-reducing pavements have a shorter service life. Therefore, this paper aimed to improve the noise-damping performance of porous asphalt mixture by adding rubber granules and extending its service life using electromagnetic induction heating self-healing technology. Porosity and permeability coefficient test, Cantabro test, immersion Marshall stability test, freeze–thaw splitting test, a low-temperature three-point bending experiment, and Hamburg wheel-tracking test were conducted to investigate the pavement performance and water permeability coefficients of the mixtures. A tire drop test and the standing-wave tube method were conducted to explore their noise reduction performance. Induction heating installation was carried out to study the heating rate and healing performance. The results indicated that the road performance of the porous asphalt mixture tends to reduce with an increasing dosage of rubber granules. The road performance is not up to the required standard when the dosage of rubber granules reaches 3%. The mixture's performance of damping and noise tends to increase with the increase of rubber granule dosage. Asphalt mixtures with different rubber granule dosages have different noise absorption properties, and the mixture with 2% rubber granules has the best overall performance (a vibration attenuation coefficient of 7.752 and an average absorption factor of 0.457). The optimum healing temperature of the porous asphalt mixture containing rubber granules and steel wool fibers is 120 °C and the healing rate is 74.8% at a 2% rubber granule dosage. This paper provides valuable insights for improving the noise reduction performance and service life of porous asphalt pavements while meeting road performance standards. [ABSTRACT FROM AUTHOR]

In order to extend the service life of a highway power supply system and the level of new energy consumption, a power dispatching strategy considering the health status of multi-energy conversion equipment is proposed in this paper. Firstly, the energy and load forms of the highway power supply system are introduced, and the structure of the multi-energy conversion equipment, the topological structures of the DC–DC and DC–AC modules, and the operating characteristics are analyzed. Secondly, the module temperatures and output voltages are used as main parameters to establish the health indexes of DC–DC and DC–AC modules, and then the health index of the multi-energy conversion equipment is further calculated. Thirdly, the new energy consumption index is defined, and a multi-objective optimization model for power dispatching of highway power supply systems is established with the goal of improving the health index of multi-energy conversion equipment and the new energy consumption index. The case study shows that the power dispatching strategy in this paper can better control the temperature of each module, improve the health status of multi-energy conversion equipment, and have a high level of new energy consumption. [ABSTRACT FROM AUTHOR]

With the wide application of wind energy as a clean energy source, to cope with the challenge of increasing maintenance difficulty brought about by the development of large-scale wind power equipment, it is crucial to monitor the operating status of wind turbines in real time and accurately identify the specific location of faults. In this study, a CNN-LSTM-based wind motor fault detection model is constructed for four types of typical faults, namely gearbox faults, electrical faults, yaw faults, and pitch faults of wind motors, combining CNN's advantages of excelling in feature extraction and LSTM's advantages of dealing with long-time sequence data, to achieve the simultaneous detection of multiple fault types. The accuracy of the CNN-LSTM-based wind turbine fault detection model reaches 90.06%, and optimal results are achieved for the effective discovery of yaw system faults, pitch system faults, and gearbox faults, obtaining 94.09%, 96.46%, and 97.39%, respectively. The CNN-LSTM wind turbine fault detection model proposed in this study improves the fault detection effect, avoids the further deterioration of faults, provides direction for preventive maintenance, reduces downtime loss due to restorative maintenance, and is essential for the sustainable use of wind turbines and maintenance of wind turbine service life, which helps to improve the operation and maintenance level of wind farms. [ABSTRACT FROM AUTHOR]

In this study, a self-healing epoxy asphalt material was developed by incorporating coumarin groups. This material achieved microcrack self-repair under UV irradiation at 50 °C. Fluorescence microscopy observations and mechanical performance tests demonstrated significant advantages in crack filling and mechanical property recovery after repair, with the fracture toughness of the repaired epoxy asphalt reaching 69% of that in its original state. Furthermore, the synergistic effect of temperature and UV irradiation in the self-healing process enhanced the material's durability and service life. This research offers new insights and methods for developing more durable and long-lasting self-healing asphalt materials, showcasing the great potential of smart materials in infrastructure applications. [ABSTRACT FROM AUTHOR]

The Canadian highway bridge design code (CHBDC) uses the concept of a target reliability index for evaluating the load-carrying capacity of existing bridges. This index, which is based on risk to human life, is related to three aspects of uncertainties inherent in a bridge: element behaviour, system behaviour and inspection level. Analysis is yet another uncertainty in bridge evaluation. It is assumed that all bridge inspections are manual. Citing examples of tests on many instrumented bridges, another level of inspection is proposed, carried out with the help of electronic instruments and tests under controlled vehicle loads. Simple additions to the clauses of the CHBDC are proposed, which can be used to determine the optimum load-carrying capacities of existing bridges where structural monitoring information is available. [ABSTRACT FROM AUTHOR]

Relevant aspects in the design of modular expansion joints are the high fatigue stress caused by heavy load traffic and the corrosion protection. Currently, corrosion damage is often not limited to the traversable surface. Therefore, more durable expansion joints are highly desirable to extend their service life. The FOSTA research project P1574 resulted from the need for durable expansion joints and thus is aimed at hot‐dip galvanized structures. In this project about 14.000 individual damages on 6.300 modular expansion joints were evaluated, relevant hot‐dip‐galvanizing parameters were investigated and recommendations for hot‐dip galvanizing‐compatible constructions were made. In addition, the fatigue strength of existing constructions has been evaluated with regard to the current and upcoming version of Eurocode 1993‐1‐9. This evaluation will be verified in the course of cyclic tests and numerical investigations. A monitoring concept is to be designed according to the requirements of the modular expansion joints and the corresponding neuralgic points. [ABSTRACT FROM AUTHOR]

Exploring the thermochemical erosion mechanism and inhibiting the thermochemical erosion reaction is essential to improve the service life of the barrel weapon. Due to high temperature and supersonic environments of the barrel weapon, the current research on its thermochemical erosion has only stopped at the final failure moment. This paper designs an erosion analog device to simulate harsh launch environments and to investigate the erosion mechanism through a combination of removable samples. The removable samples consist of five types: artillery steel sample, Cr-plated coating sample, Cr-plated coating with laser shock peening sample, tantalum magnetron sputtering coating sample, and nano-enhanced coating sample. With 200 times erosion experiments, samples have appeared with different degrees of erosion acceleration, in which the Cr-plated coating with laser shock peening sample has the least cracks and the best corrosion inhibition performance. In addition, Cr-plated coating with laser shock peening samples with diameters of 80, 100, and 120 μm are designed, and the erosion experiments reveal that the 80 μm sample shows the best erosion inhibition performance. [ABSTRACT FROM AUTHOR]

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Stabilisation of road materials that do not meet specified requirements is a common practice in road construction. Cement and lime are among the most commonly used products for stabilisation. However, these products pose challenges in particular conditions, including rigidity and proneness to cracking, incompatibility with certain materials types and susceptibility to particular environmental conditions. In this regard, alternatives have been considered and nanotechnology-based materials have emerged as a viable option. For this study, the efficacy of Nano-Modified Emulsion (NME) for stabilisation of gravel material was investigated. The gravel material, stabilised with up to 1.5% NME was evaluated in the laboratory for mechanical strength characteristics and resistance to moisture damage. Results obtained for Static Triaxial Tests (STT) show that the NME improves the cohesion of the material by up to 54% but has no significant effect on the friction angle. Significant improvements are also noted in the results for California Bearing Ratio (CBR), Unconfined Compression Strength (UCS) and Indirect Tensile Strength (ITS) tests. The results also show that NME stabilisation improves the gravel material's resistance to moisture damage. Further investigations are recommended for repeated load triaxial tests, field trials, environmental risks and life cycle costs. [ABSTRACT FROM AUTHOR]

Recessed pavement markings are consistently utilized to withstand the impact of snowplowing and sanding operations, particularly in regions with cold climates. However, the optimal configuration of recessed pavement markings remains inadequately investigated. The objective of this study is to address this concern by conducting an assessment of the luminance of recessed pavement markings. For considering the visual demands of drivers, a luminance evaluation method based on digital imagery was implemented at first. Recessed pavement markings with various configurations were then prepared, and their luminance was simultaneously measured. The luminance of recessed pavement markings after service simulation was assessed to elucidate the luminance deterioration laws. Finally, the retroreflectivity of recessed pavement markings was evaluated for their comparative analysis and better employment. Based on the luminance deterioration with operation time as an indicator, recessed pavement markings with a thickness exceeding 0.5 mm and flush with the surface exhibited a service life twice as long as conventional pavement markings. The quantitative relationship between critical values of retroreflectivity and luminance was established [retroreflected luminance (RL) of 80 mcd·m−2·lx−1 corresponds to luminance of 200 cd/m2 ], and the minimum RL of recessed pavement markings should be as low as 90 mcd·m−2·lx−1 for practical application. [ABSTRACT FROM AUTHOR]

The vehicle dynamic load can greatly affect the service life of pavement. To study the vehicle dynamic load accurately and conveniently under different pavement characteristics and driving conditions, a multibody dynamics method was employed to establish a three-dimensional (3D) vehicle dynamics simulation model of a six-axle heavy vehicle (the most typical heavy vehicle on an expressway). Experimental tests of vehicle component parameters and axle spindle loads were performed to provide simulation parameters and to validate this vehicle dynamics model, respectively. The validation results showed that the accuracy and robustness of the dynamics model were satisfactory. Based on the validated model, the effects of International Roughness Index (IRI) and vehicle speed on the dynamic load coefficient (DLC) were explored. The DLC increased by about 80% when the speed or IRI changed from 30 km/h or 1.184 m/km to 70 km/h or 3.551 m/km , respectively. To better evaluate the effect of dynamic load, the relationship between the DLC of the vehicle and the vehicle speed and IRI is proposed according to simulation results. This relation equation can quickly and accurately study the DLC of this heavy vehicle under different IRI pavements and driving speeds. Because the vehicle dynamics model is convenient for studying the dynamic load under different conditions, this method is recommended in vehicle–pavement coupled analysis. [ABSTRACT FROM AUTHOR]

Pavement growth (PG) refers to the expansion of the integrated slab length when all the contraction joints of the concrete pavement are close within the expansion joint (EJ). It results from the complex interactions of numerous factors, such as climatic conditions (extremely high temperature and moisture levels), material, and the quantity of incompressible particles infiltrating the pavement joints structure. Currently, the methods and guidelines available for evaluating the annual PG and predictions of concrete pavement blowup are considerably limited. In this study, a mechanistic design framework was developed for estimating the PG and predicting pavement blowup potential. Moreover, a computer tool called Pavement Growth and Blowup Analysis (PGBA) was developed using MATLAB. This tool considers factors such as the pavement configuration, climatic conditions, configuration of EJs, and design reliability. It was used to evaluate the effectiveness of EJs and predict the blowup occurrence times for concrete pavements. To evaluate the PGBA tool, PG data from field measurements conducted by the Maryland DOT were compared with the results obtained using the PGBA tool. The PG predicted by the PGBA tool shows good agreement with the field measurements. However, because concrete pavement blowup data corresponding to PG measurement were not available, a comparison of the PGBA blowup results was not possible. The PGBA tool can be used to predict the service life of EJs and the blowup occurrence time according to the climatic data, pavement structure and materials, joint design, base friction characteristics, and engineering judgment. [ABSTRACT FROM AUTHOR]

This article addresses the challenge of comparing in‐service weatherability among newly developed coatings. The study aims to compare the durability of three thermoplastic polyurethane‐based coatings specifically formulated for defense inflatables. It introduces a reliability model that incorporates two weathering stresses, namely, ultra‐violet radiation and temperature, to predict the service life of the coatings. A life–stress relationship has been established from the accelerated aging tests, which facilitates the determination of material service life at use level conditions. Notably, the analysis underscores the significant improvement in service lifetime achieved with nanocomposite‐based coatings. The validity of the proposed model is established through comparison with real‐world field test data, emphasizing the effectiveness of the approach in assessing and comparing the performance of the three coated samples. The insights gained from this research will surely contribute to enhancing the durability assessment of coated systems in real‐world conditions for various fields of applications. Highlights: Introduces a unique method to compare weatherability of three polyurethane coatings.Reliability model predicts service life under UV and temperature stresses.Life–stress relationship via accelerated aging for accurate service life.Nanocomposite coatings show longer service life than conventional ones.Model validated with field data, confirming practical applicability. [ABSTRACT FROM AUTHOR]

In all areas of application, adhesive joints are exposed to environmental conditions, which can weaken the joint. To verify the functionality of the joints for a certain service life, accelerated ageing tests are used. To assess the mechanical performance of aged joints, single lap joints (SLJ) are often used. The influence of various geometries of SLJ on the strength and stress behaviour is known. The various ageing processes in bonded joints are not yet sufficiently known. Thus, the influence of the specimen geometry on the ageing behaviour cannot be reliably estimated and is therefore investigated in this work. SLJ with different geometries made of an AlMgSi alloy and a one-component epoxy-hybrid adhesive were artificially aged. T dimensions of the SLJ were varied in width, overlap length, adhesive thickness or joint design. Similar ageing results were seen in a significant shorter time with narrower samples or shorter overlap length. A SLJ with a bonding area of 6.3 mm x 6.3 mm was derived from these results. After 4–5 weeks of ageing, this shows comparable results to the standard test SLJ after 8 weeks. This allows to speed up industrial ageing tests nearly by factor two without changing ageing mechanisms. [ABSTRACT FROM AUTHOR]

The heat aging resistance of a peroxide-cured silicone rubber (VMQ) in the temperature range from 75 to 225 °C was investigated. Activation energies for the degradation process were calculated in order to understand the durability and lifetime of the rubber. The hardness, tensile stress at 10% elongation, and chemical cross-link density measured by solvent swell and double-quantum nuclear magnetic resonance increase as a function of thermal aging. The increase is due to the prevalence of cross-linking reactions over chain scission events which was confirmed by FTIR analysis. The unaged monomodal cross-link distribution becomes more heterogeneous with heat aging as its distribution significantly widens toward higher cross-link densities. Calculated activation energies for the heat-induced degradation process were between 70 and 101 kJ/mol. Activation energies depended on the experimental test used to probe the system. The FTIR analysis confirmed the loss of –CH bonds and gain of Si–O–Si linkages during thermal aging. Oxidative products were extracted and characterized from the degraded VMQ. Aerobic and non-aerobic degradation mechanisms have been proposed to explain the presence of cross-linking and chain scission reactions. Given the lack of data change during low-temperature aging, the results are suitable for use to predict the performance of VMQ in applications between 100 and 225 °C. [ABSTRACT FROM AUTHOR]

Freeze-thaw resistance ability of concrete is an important issue when evaluating its durability. In this research, the objective was to predict concrete resistance to such cycles by analyzing water absorption based on the critical water saturation theory. In order to achieve this goal, detailed experiments were conducted, including water absorption, pore structure scanning, and mercury intrusion porosimetry of concrete with air-entraining admixture and different fiber content to obtain critical indicators, such as water absorption, porosity, and air void spacing factor, which formed the basis for predicting the service life of concrete. To predict the service life of concrete under freeze-thaw cycles, the critical saturation theory was utilized, taking into account environmental parameters and experimental indexes. The service life of concrete against freeze-thaw using air-entraining admixture and fibers had been calculated quantitatively in this paper. The results show that the predicted service life of concrete with air-entraining admixture was increased by more than 50 times, and using both air-entraining admixture and fiber could increase the service life by more than 80 times, even reaching 249 years. [ABSTRACT FROM AUTHOR]

Microstructural stability and submerged properties of aluminium alloys are critical to their integrity and service life in corrosive environments. Submerged friction stir processing (SFSP) and friction stir processing (FSP) have become effective methods for improving the surface characteristics of these alloys, potentially mitigating corrosion-related degradation. This study provides a analysis of the corrosion behaviour of aluminium alloys post-FSP/SFSP processing. The study reveals that FSP/SFSP can significantly refine grain structure, modify the distribution of intermetallic phases, and influence the nature of the oxide film, thereby affecting the corrosion resistance. The findings suggest that optimal FSP/SFSP parameters can be engineered to develop a corrosion-resistant microstructure while preserving the mechanical attributes of the aluminium alloys. This paper contributes to the improvement of knowledge regarding the corrosion processes in FSP/SFSP-treated aluminium alloys in order to use them in various working environments. The alternation in corrosion dynamics as a function of the modified surface conditions could be identified by using electromechanical assays, surface analytical techniques, and microstructural examinations. [ABSTRACT FROM AUTHOR]

Asphalt pavement is demolished and milled at the end of its service life, resulting in an enormous amount of waste material known as reclaimed asphalt pavement (RAP). Using cold recycling techniques, it is possible to reuse RAP for base course construction. However, using a high amount of RAP could have negative effects on the mechanical properties and durability of the base course. In this study, to improve the performance of asphalt emulsion recycled base course prepared with RAP, asphaltenes derived from Alberta oil-sands bitumen was added to the mixture. The performance properties of the selected mixtures were investigated at high, intermediate, and low temperatures. Testing results and statistical analysis revealed that asphaltenes enhances the high and intermediate temperature performance of the modified mixes significantly. The low-temperature creep compliance of asphaltenes-modified mixtures was slightly lower than the unmodified mixtures, however, the low-temperature properties of the modified mixes were not significantly affected. [ABSTRACT FROM AUTHOR]

This study presents correction factors for the Norwegian fatigue load model for railway bridges. The fundamental idea of a correction factor is to ensure that the load model induces the same fatigue damage as actual traffic. Load measurements from traffic on a representative line on the Norwegian railway network are used to propose correction factors for improved fatigue life estimation with freight and passenger trains. Correction factors improve the accuracy of the estimated fatigue life and reduce the conservatism of the load model. The validity and conservatism of the most damaging train assumption for fatigue load modeling is also considered. The suitability and consequences of using the proposed correction factors for other lines and historic traffic are discussed. [ABSTRACT FROM AUTHOR]

This research is based on the modeling, internal structure analysis, and automation of a cassava grinding machine. For the design, the single-cylinder grinder was chosen due to its advantages, notably simplicity and versatility. The grinding method used in this type of grinder is compression. The mechanical design and simulation software first allowed for the design of the grinder and then for performing static analyses under three loads (P1 = 10000N, P2 = 15000N, and P3 = 20000N). The results of these tests led to the selection of P3 = 20000N as the straightening load, with a maximum stress value in the static analysis of 88,18 MPa and a maximum deformation of 0,000358 under the force of load P3. Additionally, the frequency analysis distinguished five resonance modes. The results for each mode concluded that no resonance would affect the machine, thus ensuring stable operation. Furthermore, fatigue, frequency, and safety factor studies showed that the machine could withstand a load of m3 = 2000 kg without damage, with a service life of 1e+09 cycles. Considering the total number of life cycles, which is 1e+09 cycles, this means that the machine will have a service life of 347000 years, with a total grinding output of 2e+12 kg of cassava and 5840000 kg per year. The factor of safety is FoS = 1,78, indicating a sufficient margin for safe operating conditions. The automation of the grinder was carried out using a GRAFCET model and a sophisticated human-machine interface (HMI), providing an additional safety point for the machine and allowing the operator to monitor the operation via a simple graphical interface. This automation enables continuous operation with minimal human intervention, thereby improving the efficiency and safety of the cassava grinding process. [ABSTRACT FROM AUTHOR]

The cross beam of a mining linear vibrating screen is prone to cracking under long-term cyclic load. In order to accurately predict the fatigue life of the cracked cross beam, a coupled analysis method of vibration and crack propagation is proposed. A 2D dynamic model of the vibrating screen is established based on the finite element method, which is verified by the vibration test platform. The cracked Euler beam element is used to model the cracked cross beam. The effects of crack depth, amplitude of excitation force, frequency of excitation force, and crack location on the crack-tip stress intensity factor of the cracked cross beam are investigated in detail. In addition, an iterative method is proposed on the basis of the Paris model. The residual service life of the beam under different frequencies of excitation force, amplitudes of excitation force, spring stiffness, crack positions, and degrees of stiffness imbalance are discussed. The results demonstrate that the fatigue life of the beam increases as the frequency of excitation force and spring stiffness increase. The increase of the amplitude of excitation force and spring permanent deformation reduces the fatigue life. The conclusion obtained provide some theoretical guidance for the design and routine maintenance of mining linear vibrating screens. [ABSTRACT FROM AUTHOR]

Workover operations significantly impact the service life and gas production capacity of coalbed methane (CBM) wells and are crucial for optimizing resource exploitation. To investigate workover operations' impact on coal seam reservoirs, the authors designed a series of experiments and obtained the following results: (1) The workover operation induced a phase transition in the solid-liquid composition produced by the CBM well, indicating changes in the coal reservoir's internal structure. (2) During the stable production stage before and after the workover, the proportion of Na+, Cl−, Ca2+, and Total Dissolved Solids (TDS) in the water samples showed a downward trend as a whole, while the HCO3−; after the workover, the Na+, Cl−, Ca2+, and TDS all increased suddenly, while the HCO3− decreased. (3) While inorganic minerals predominated in the precipitation material during the stable production stage pre-workover, their proportion decreased post-workover, with a noticeable shift in their qualitative composition. (4) It is an indisputable fact that workover operations cause physical and chemical damage to coal seam reservoirs. During workover operation, how to avoid damage and conduct benign reconstruction to the reservoir will be the direction of our future efforts. The experimental results provide valuable insights that can guide the optimization of CBM workover operations and inform the strategic planning of subsequent drainage activities. [ABSTRACT FROM AUTHOR]

Defective welds substantially hinder the quality of a welded joint, and choosing the best process parameter to ensure tunnel defect-free welds requires extensive experimentation. A coupled Eulerian–Lagrangian (CEL) finite element (FE) model was proposed to predict the defect formation, thermal history, and material flow behavior of the friction stir welding (FSW) process. The formation of defects was examined by varying tool rotation speed (TRS) between 600 and 1800 rpm and welding speed (WS) between 30 and 90 mm/min, with a constant tilt angle of 0°. It was evident that selecting appropriate process parameters established the condition for a tunnel defect-free joint. Less temperature of 300.2 °C can't initiate proper material plasticization, leading to reduced material consolidation and more flash generation, thereby generating a long-stretched tunnel defect sample (S1). In contrast, a maximum temperature rise of 595.6 °C in the tunnel defect-free specimen (S2) ensures sufficient frictional contact between the tool-workpiece, thereby increasing material plasticization and enhancing material flow. Variation of less than 10% was found between the observed and simulated transient thermal histories. A minor percentage error of 5.44% in length and 1.28% in width was measured between the experimental and numerical tunnel defect morphology of S1. Contrarily, percentage errors of 4.16% in length and 3.75% in width were recorded for S2. Complete dynamic recrystallization in S2 hinders the formation of lamellar grain structures and flow segregation, leading to fine granular morphology. Maximum von Mises residual stress of 370 MPa was evident to spread all over the welded path in S1, thus hindering its service life. In comparison, 470 MPa were recorded at the crown of the chips of S2, which can be machined. A percentage error of 11.9% for sample S1 and 4.07% for S2 was marked when validating for average axial force data deviation. The proposed methodology was fairly well validated with the experimental trials. [ABSTRACT FROM AUTHOR]

β‐flecks are a type of segregation defect commonly encountered during the solidification of titanium alloys enriched with β‐stabilizing elements. These defects are associated with a detrimental impact on mechanical properties, which potentially limit the service life of parts containing them. Despite their significance, a standardized method for identifying these defects is lacking. In this study, a systematic approach is provided to detecting and characterizing β‐flecks in a representative metastable β‐Ti alloy and β‐C (ASTM Grade 19/Ti–3Al–8V–6Cr–4Mo–4Zr). By combining low temperature but prolonged aging, time‐dependent etching, and Fiji‐assisted image analysis, the presence and characteristics of β‐flecks are determined with precision and impartiality. This straightforward technique offers a reliable means for visualizing and quantifying β‐flecks in titanium alloys. It establishes a foundational framework that can be broadly applied to various β‐Ti alloys prone to β‐fleck formation. [ABSTRACT FROM AUTHOR]

Bolt loosening can significantly impact the accuracy, stability, and safety of equipment. The detection of bolt loosening in a timely manner is crucial for ensuring the safety, reliability, performance, and service life of equipment, structures, and systems. Various methods exist for detecting bolt loosening, such as strain gauges and ultrasonic waves. However, these technologies have some limitations that impede their widespread application. In this paper, for the high-pressure pipe manifolds that may experience leakage accidents due to the loosening of bolts, an early bolt loosening detection method based on digital image correlation is proposed. Initially, a model is established through tensile tests to relate the average strain on the side of the bolt head to the axial force. Subsequently, an industrial camera captures images of bolts with random speckles under operational conditions. Using digital image correlation technology, the average strain in a specific region on the side of the bolt head is calculated. By integrating the average strain into the established relationship model between the average strain and axial force, the axial force of the bolt under operational conditions can be predicted, enabling the early assessment of bolt loosening. The findings show that the average strain on the side of the bolt head increases proportionally with the axial force, indicating a strong linear relationship. This method enables accurate prediction of the bolt's axial force, offering a new approach for identifying the early loosening of bolts in high-pressure manifolds and monitoring structural health. [ABSTRACT FROM AUTHOR]

To repair and extend the service life of mobile-contact parts, laser cladding technology was applied to prepare CrB2/Cu coating on Cu–Cr alloy substrate, which was simulated as actual servicing parts, and the current-carrying friction property, including that friction coefficient, wear rate as well as current-carrying efficiency were studied. Results show that most of the CrB2 particles retain while some decompose into CrBx phases during the laser cladding process. With the increase of electric current, the average friction coefficient of CrB2/Cu coating grows first followed by going down. In comparison to the CrB2/Cu coating, the wear rate and average friction coefficient of QCr0.5 substrate always grow with increasing electric current values. When the current is 20A, the COF and wear rate of composite coating are about 0.737 and 1.37 × 10–4 mm3/N•m, which are about 21% and 79% of that of QCr0.5 alloy, respectively, and the major wear mechanism of CrB2/Cu coating is the adhesive wear. Moreover, the CrB2/Cu composite coating has low friction coefficient, low wear rate and high current-carrying efficiency under high electric currents, as a consequence, the CrB2/Cu coating has better current-carrying friction and wear performance under high current conditions. [ABSTRACT FROM AUTHOR]

Polymer composites bonded with natural fibers are extensively used for a range of engineering purposes. Preserving their mechanical strength and estimating their maximum service life are thus essential for efficient usage. The primary goals of this effort are to analyze and forecast the longest possible life span of composites. To do this, Fick's law and the Arrhenius principle are employed to analyze the diffusion coefficient and activation energy. Compression molding technology and a manual technique for layup were employed to make the composites reinforced with epoxy laminate and woven mats of jute fiber (JRC). Three layering patterns were used to prepare the laminated composite: 45° angle‐ply laminate [0°/+45°/0°/−45°/0°], 0° balanced laminate [0°/0°/0°/0°/0°/0°], and 30° angle‐ply laminate [0°/+30°/0°/−30°/0°]. In order to examine how aging affected the composites' mechanical properties, the materials were immersed in water for 10, 20, 30, and 40 days throughout the study. The study's conclusions showed that the composite samples' weight rose with age. It was possible to make precise predictions about strength retention by comparing the mechanical characteristics of aged (wet) and unaged composites. It was discovered that the strongest composites were those with a 45‐degree stacking pattern. The activation energy of composites with a 45° angle‐ply laminate layering pattern is maximum, according to the Arrhenius principle. Additionally, using an electron microscope with scanning capabilities (SEM), it was possible to determine the fiber matrix and the tensile cracked surface contact connection. Highlights: The widespread usage of polymer composites with natural fibers in engineering applications.Preservation of mechanical strength and predicting the maximum service life of these composites show how important these materials are for engineering efficiency.Fick's rule and the Arrhenius principle are used to analyze diffusion coefficient and activation energy.Laminated composites are made using 45° angle‐ply, 0° balanced laminate, and 30° angle‐ply layering patterns.The impact of simulated aging on composite mechanical characteristics by water immersion for varied periods. [ABSTRACT FROM AUTHOR]

The machining quality plays a pivotal role in determining the service life of components. In this context, the primary focus of the experimental investigation is centered on the impact of cutting conditions during edge trimming of carbon fiber reinforced plastics (CFRP) material. The ultimate objective of this experiment is to pinpoint the most effective machining parameters, specifically the cutting speed, Vc and the feed per tooth, fz, to minimize damages during the edge trimming process using actual aerostructural sample components composed of CFRP material. Furthermore, the study took into account the issue of tool wear on cutting tools. The Design of Experiment (DoE) technique, specifically the Taguchi L9 orthogonal arrays method, was used to conduct this research. It was shown that the feed per tooth, fz, and the cutting speed, Vc, had the biggest effects on the trimmed surface quality as the longitudinal surface roughness increased. It was demonstrated that the fracture of the pyramidal tooltips in router-type tools happened more frequently at higher cutting speeds, Vc. The optimal machining parameters for minimizing damages during CFRP edge trimming were the combination of the feed per tooth, fz at 0.05 mm and cutting speed, Vc at 50 m/min. The most significant element influencing the tool's wear was the cutting speed, Vc. [ABSTRACT FROM AUTHOR]

Polymers may suffer from sudden mechanical damages during long‐term use under various harsh operating environments. Rapid and real‐time self‐healing will extend their service life, which is particularly attractive in the context of circular economy. In this work, a lignin cluster polymerization strategy (LCPS) was designed to prepare a series of lignin functionalized polyolefin composites with excellent mechanical properties through nickel catalyzed copolymerization of ethylene and lignin cluster monomers. These composites can achieve rapid self‐healing within 30 seconds under a variety of extreme usage environments (underwater, seawater, extremely low temperatures as low as −60 °C, organic solvents, acid/alkali solvents, etc.), which is of great significance for real‐time self‐healing of sudden mechanical damage. More importantly, the dynamic cross‐linking network within these composites enable great re‐processability and amazing sealing performances. [ABSTRACT FROM AUTHOR]

Parallel-connected digital valve arrays are commonly utilized in the pilot stage of the proportional directional valve to enhance dynamic performance and reliability. However, when the digital valve array is driven by a digital signal, it is difficult to optimally assign the signal pulses to each valve. If the assignment is not well executed, it can significantly reduce the switching uniformity of the digital valves or lead to performance degradation of the system. In this paper, a model-based sliding mode control strategy based on the intelligent distribution of control law is proposed and successfully applied to a proportional valve driven by digital valve arrays. The intelligent distribution strategy encompasses a logic distribution algorithm and a circular sliding distribution algorithm that automatically assigns control laws to different valves based on the rolling of the PWM signal cycle. Experimental results confirm that the proposed strategy not only simultaneously reduces the total number of valve switches and enhances the switching uniformity among the valves, but also adapts to the variation in the number of valves. The proposed strategy is not limited to the application of digital valve arrays, it is also applicable in other fields of multi-actuators driven by digital signals, and can simultaneously improve the control accuracy, lifetime, and maintenance friendliness. • A digital proportional valve is proposed, where the pilot stage consists of fixed orifices and digital valve arrays. • The intelligent distribution strategy is designed based on a logic distribution and a circular sliding distribution. • The proposed MSMC with intelligent distribution can be adapted to DVAs with any number of valves. [ABSTRACT FROM AUTHOR]

To provide convenient access to service ducts, beam and girder web openings are very prevalent in practice. The insertion of a reinforced concrete (RC) beam into the web, however, reduces the stiffness and strength of the beam because of the local cracking around the aperture. The employ of fiber-reinforced polymer (FRP) laminas in general and not a specific type of them for reinforcing the holes was showed in this paper including their dimension and some design parameters change, such as the number and placement of (FRP) sheets near the opening. The experimental work was presented by comprised the testing of ten reinforced concrete beams, four of them were tested without reinforcement, five of which had (FRP) sheets around the opening for reinforcement, and the remaining beam was solid. The (FE) program consists of ten beams were modelled by using Abaqus, one of them was control solid beam and other nine beams were with hollow. The load-deflection relationships were evaluated before failure, and crack patterns were obtained and compared with the experimental results available. The numerical and experimental results agreed well. Reinforced concrete beams are the cornerstone of modern infrastructure, carrying heavy loads and forming the basic structure of buildings and structures. However, these beams may be damaged or deteriorated over time due to multiple factors such as corrosion, overload, moisture, and fire. In addition, the need to make modifications or openings in these beams for maintenance or service installation purposes may negatively affect their load-bearing capacity. To overcome these challenges, modern techniques have emerged to strengthen concrete elements, the most important of which is the technique of strengthening concrete with fiber reinforced polymer (FRP). This technique is highly effective in increasing the load-bearing capacity of concrete beams, improving their performance under different loads, and extending their service life. A brief critique of the limitations of existing studies should be included to highlight the significance of the present work. Inadequate studies on the interaction between FRP and concrete: There are still gaps in our understanding of the interaction between FRP and concrete at the microscopic level, which affects the accuracy of computational models. The research focused on the behavior of FRP-reinforced concrete hollow core beams under different loads, filling a gap in previous research. The research combined computer simulations and laboratory tests to ensure the accuracy of the results and provide a comprehensive picture of the behavior of the beams. The research identified the best methods for applying FRP sheets to improve the load-bearing capacity of beams around openings, providing practical guidance for engineers. [ABSTRACT FROM AUTHOR]

Heterogeneous crystallization resulted in low conversion efficiency and short service life has become one of the important challenges of desalination. Here, a fluoro-modified CNT@epoxy composite coating is developed to durably inhibit salt crystallization of photothermal sheet even in highly concentrated salt water. Typically, it can have stable evaporation efficiency of ∼ 1. 7 0 kg ⋅ m − 2 ⋅ h − 1 without salt crystallization after continuously being operated for 40 cycles under one solar intensity in the 20 wt.% NaCl solution. That is mainly due to the Cassie state superhydrophobicity that can large increase the heterogeneous nucleation barrier quite close to the homogeneous one in salt water. This study expects to solve the existing problems of complex structure and short service time of seawater desalination units. We have constructed a photothermal sheet using superhydrophobic CNT@epoxy composite coating. It showed excellent photothermal conversion ability to inhibit heterogeneous crystallization, which it can maintain (∼1.70 kg.m–2.h–1) in salt water with high concentrations of NaCl (5–25 wt.%), even after continuous evaporation for 40 cycles in 20 wt.% NaCl solution. [ABSTRACT FROM AUTHOR]

Methanol is a key product connecting modern coal chemical industry and traditional coal chemical industry. Industrially, methanol is typically produced by the reaction of syngas under the action of the catalyst. The service life of methanol synthesis catalysts is usually 3 to 4 years, and ensuring the normal service life of methanol synthesis catalysts is of great significance to methanol enterprises. Typical cases of sulfur poisoning and iron poisoning in industrial methanol synthesis catalysts were analyzed, and the poisoning mechanisms were explained based on literature data. It is pointed out that iron poisoning and sulfur poisoning are the main causes of methanol synthesis catalyst deactivation. Corresponding countermeasures were provided, which can offer guidance for ensuring the normal service life of methanol synthesis catalysts. [ABSTRACT FROM AUTHOR]

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