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This study proposes an approach for the design of gradation plans via the establishment of mathematical models for particle gradation, enabling control over the particle gradation of different sizes of SiO2. Silica‐based ceramic cores were produced follow the above strategy for precision casting, and the impact of particle gradation and sintering regimes on the shrinkage rate and relevant mechanical properties of the silica‐based ceramic cores were investigated. The results suggest that an optimal gradation plan can effectively enhance the density of silica‐based ceramic cores, thereby influencing the shrinkage rate and mechanical properties at both room and elevated temperatures. The shrinkage rate of the silica‐based ceramic cores is influenced by the chosen gradation particle size range of the silica; the sintering regimes have notable effects on mechanical properties of the silica‐based ceramic cores. The performance data of the samples demonstrate the efficacy of applying the gradation plan to the B60 samples with an average particle size of 60 µm in the largest grade. After undergoing a final sintering temperature at 1160°C and holding for 5 h, the shrinkage ratio could be limited to 1.33%, the room temperature bending strength reached 15.0 MPa, and the high‐temperature bending strength could be enhanced to 37.6 MPa. These findings present a significant reference values for the production of single‐crystal hollow blades. [ABSTRACT FROM AUTHOR]

Abstract The use of bio-based biomass construction materials has the advantage of helping to reduce fossil energy demand, protecting the environment from carbon dioxide emission and reducing the production of non-degradable waste. This paper used resin-modified soy protein (SP) adhesive to combine rice straw stalks, and made straw-soy protein composites (SSPC) material. The physical properties, compressive behavior and stability during wetting drying cycles of SSPC were measured. Due to water evaporation, the SP matrix is full of connected pores, resulting to its physical properties of small density, high shrinkage ratio and low thermal conductivity, which are 0.24 g/cm3, 16.2%, and 0.065 W/(m•K), respectively. Adding straw is helpful to the physical properties of SP matrix, leading to an obvious decrease in shrinkage ratio and thermal conductivity of SSPC, which are 8.51% and 0.075 W/m•K. Furthermore, the compressive load–displacement curves of SSPC groups divide into two types: divergent and convergent. The compressive strength of divergent samples is decided by the critical displacement determined according to the convergent specimens. It shows that straw stalk proves the positive effect on the compressive property of SP matrix. As to the mass of SSPC samples during the wetting drying cycles, it drops apparently in the initial three cycles, and becomes negligible from the fifth cycle, meaning that the stability of SSPC during wetting drying cyclic process is quite good. The research result would be helpful for using SSPC as building material, especially as thermal insulation material.

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Aramid nanofiber (ANF) based porous materials have been widely applied in thermal insulation, high-efficiency adsorption, and sensing technologies. However, significant volume shrinkage of ANF products during freeze-drying is inevitable due to the organic solvent used in the fabrication. This shrinkage leads to increased density and a reduced performance. In this study, we propose a method for fabricating ANF foam that utilizes Ni foam as an antideformation sacrifice layer to suppress the shrinkage induced by dimethyl sulfoxide (DMSO). The Ni foam is immersed in an ANF-DMSO dispersion, followed by solvent exchange and freeze-drying, during which a thin ANF layer is coated onto the foam skeleton. Subsequently, the ANF foam is obtained by etching the Ni skeleton and drying. The fabricated ANF foam exhibits an ultralow density of 7.98 mg/cm3 and demonstrates exceptional structural stability. The foam exhibits outstanding mechanical properties and a remarkable load-bearing capacity, withstanding a weight of over 1229 times its own weight without structural damage. Furthermore, the ANF foam showcases superior thermal insulation and flame-retardant properties. It retains the structural characterization of abundant active sites on the surface and within its pores, enabling it to be functionalized with carbon nanotubes (CNT), designed to function as a self-heater and to absorb and degrade organic solvents. [ABSTRACT FROM AUTHOR]

Unmanned aerial vehicles (UAVs) have increasingly become integral to multi-access edge computing (MEC) due to their flexibility and cost-effectiveness, especially in the B5G and 6G eras. This paper aims to enhance the quality of experience (QoE) in large-scale UAV-MEC networks by minimizing the shrinkage ratio through optimal decision-making in computation mode selection for each user device (UD), UAV flight trajectory, bandwidth allocation, and computing resource allocation at edge servers. However, the interdependencies among UAV trajectory, binary task offloading mode, and computing/network resource allocation across numerous IoT nodes pose significant challenges. To address these challenges, we formulate the shrinkage ratio minimization problem as a mixed-integer nonlinear programming (MINLP) problem and propose a two-tier optimization strategy. To reduce the scale of the optimization problem, we first design a low-complexity UAV partition coverage algorithm based on the Welzl method and determine the UAV flight trajectory by solving a traveling salesman problem (TSP). Subsequently, we develop a coordinate descent (CD)-based method and an alternating direction method of multipliers (ADMM)-based method for network bandwidth and computing resource allocation in the MEC system. Extensive simulations demonstrate that the CD-based method is simple to implement and highly efficient in large-scale UAV-MEC networks, reducing the time complexity by three orders of magnitude compared to convex optimization methods. Meanwhile, the ADMM-based joint optimization method achieves approximately an 8% reduction in shrinkage ratio optimization compared to baseline methods. [ABSTRACT FROM AUTHOR]

Deformation and surface-checking defects in wood are closely related to the drying stress caused by shrinkage and moisture content (MC) gradients throughout the drying process. In this study, 50-mm-thick Masson pine (Pinus massoniana Lamb.) lumber was used as the research object. The drying stress caused by shrinkage behavior and MC changes was monitored, and the development of surface checks was observed during the drying process. Results showed that when the average MC was 60%, the free water in the surface layer of lumber evaporated completely, causing the MC to decrease below the fiber saturation point (FSP). The surface layer was subjected to tension stresses, resulting in surface checks which primarily distributed in the latewood area and propagated longitudinally. When the average MC was between 30% and 40%, the combined effects of the high MC gradient and anisotropic shrinkage of the wood resulted in further expansion of the checks. As the average MC decreased to less than 20%, the MC of the core layer lumber decreased below the FSP, resulting in the closure or even disappearance of most surface checks. The critical point (average MC of 60%) of drying stress was obtained, which can benefit the fine-tuning of kiln-drying schedules and improve the drying quality of Masson pine wood. [ABSTRACT FROM AUTHOR]

Polyformaldehyde (POM) and Polyamide 66 (PA66) are engineering plastics with excellent mechanical properties and thermal stability. Producing microcellular injection molded POM and PA66 parts with high dimensional accuracy would be beneficial to reduce material cost and product quality. In this research, foamed POM and PA66 gear parts were fabricated by using microcellular injection molding with supercritical nitrogen as the blowing agent. Compared to conventional injection molded parts (parts that foaming is not involved), the foamed POM and PA66 gear parts achieved 5% and 10% average weight reduction, respectively. The foamed parts displayed a lower shrinkage ratio when compared to the solid counterparts, which was attributed to the cell expansion that offset part of the inward shrinkage stress. Moreover, POM gear parts with a higher crystallinity degree presented more serious shrinkage ratio compared to the PA66 gear parts, which contributed to the denser polymer molecular chains arrangement. The shrinkage ratio in both directions of PA66 foamed gear parts depended on the injection volume, and the lowest shrinkage ratio of 0.043‰ was obtained at the injection volume of 74 mm, when the polymer reached the maximum foaming ratio. The findings from this study could provide practical guidance for preparing microcellular injection molded products with high dimensional accuracy. [ABSTRACT FROM AUTHOR]

Coated sands are used extensively for additive manufacturing sand molds in the metal casting process, and the packing structure changes caused by the resin fl ow promote the shrinkage and deformation of the part. During the coated sand heating, the resin on the surface fl owing to the contact points of the particles forms the resin neck and causes particles to pack close to each other. In this work, the diameters of the coated ceramsite sand before and after heating were measured based on in-situ experimental observations with image measuring apparatus and blue laser, to obtain the relationship between resin coating thickness and the particle diameter. The particle packing model was established to describe the particles’ achievement of a stable state one by one. A re-packing simulation was then performed after reducing the particle diameter according to the resin coating thickness, to obtain the shrinkage ratios at different particle size distributions. It was found that the resin coating thickness increased from 0.8 to 2.3 μm as the particle diameter increased from 107 to 500 μm, for the coated ceramsite sand with the resin content of 2wt.%; the shrinkage ratio decreased fi rst and then increased as the particle diameter increased. The experimental minimum shrinkage ratio was 3.28%, and the corresponding particle diameter was 300-375 μm, while the minimum shrinkage ratio obtained by simulation was 3.43%, and the corresponding particle diameter was 214-300 μm. After mixing the fi ve groups proportionally, the shrinkage ratios of the simulation and experiment dropped to 2.81% and 3.04%, respectively, indicating the best results.

The droplet coalescence phenomenon extensively exists in the industrial production and application, as well as in nature, which is of great research significance. This paper adopted the molecular dynamics (MDs) simulation method to investigate the behavioral characteristics of water/water, ethanol/ethanol and water/ethanol nanodroplets coalescence. The results suggested that, in water and ethanol nanodroplet coalescence process within the water/ethanol system, ethanol was always wrapped on the outer layer of water droplets. The droplet shrinkage in the water/water system was greater than those in the other two systems; meanwhile, that in the water/ethanol system rapidly increased after the contact of droplets, and subsequently surpassed that in the ethanol/ethanol system. [ABSTRACT FROM AUTHOR]

Fried carrot slices feature high fat content to impair people healthy. To resolve this issue, microwave hot air-assisted pulse-spouted vacuum drying (MHAPSVD) has been designed using microwave vacuum dry on pulse-spouted bed with hot-air steam. Dying characteristics, moisture mobility and qualities of carrot slices had been confirmed after dying using 915 MHz microwave generator. Experiment was carried out at 3 W/g, 90 °C air stream, 0.08 MPa vacuum pressure and 2 s pulse interval for drying time of 10–80 min. The quality properties of color, odor, rehydration ratios, shrinkage ratios as well as tastes in 70 min drying are found to be suitable for a snack food. High moisture stability of carrot slices was achieved after 50 min. Free water decreased dramatically from start to 20 min and bound water declined sharply from 20 to 50 min. MHAPSVD could be a high efficient and quality drying technology for crisp product. [ABSTRACT FROM AUTHOR]

[Display omitted] • A visual gasification system with monitoring particle shrinkage and product was developed. • Inverse steam gasification kinetics based on gas product release law in fluidized bed. • New insight into morphology-kinetics correlation for steam gasification were gained. • Synergistic regulation of steam pressure and temperature achieved high H 2 /CO of 2.46. • Shrinkage rate peaked at the transition from pyrolysis to char gasification (20% CCE) Biomass steam gasification technology has attracted considerable interest for its potential of low-cost and high-efficiency in hydrogen production. However, there is still a large knowledge gap regarding morphology-kinetic correlation. To avoid the technical difficulties of thermogravimetric analysis and fixed bed studying steam gasification kinetics, this work pursues the design and building of a visualized bubbling fluidized bed with an online analysis system. According to the morphology evolution of biomass real-time observed by a high-speed camera, the shrinkage ratio during high-temperature gasification in a fluidized bed has been first deduced. Moreover, based on accurate monitoring of the gas products releasing behavior, multiple kinetic models were applied to evolve the activation energy at different carbon conversion efficiencies (CCE). The results showed that the synergistic regulation of steam concentration and temperature achieved a high H 2 /CO ratio (2.46) and H 2 yield (869.5 L/kg). A comparative analysis of the coupling relationship between shrinkage ratio, activation energy and CCE successfully separated the volatile precipitation and char gasification processes. It was also revealed that the shrinkage rate peaked at the transition from pyrolysis to char gasification (20 % CCE). At CCE below 20 %, the reaction mechanism tended towards a nucleation and growth mechanism. As CCE reached 20 %, the reaction form shifted. Subsequently, the chemical reaction mechanism controlled the main reaction, and the average apparent activation energies of H 2 , CO 2 and CO were 86.76, 31.27 and 39.90 kJ/mol, respectively. This work provides new insights and a theoretical basis for understanding and modeling the biomass steam gasification process in fluidized beds. [ABSTRACT FROM AUTHOR]

Coated sands are used extensively for additive manufacturing sand molds in the metal casting process, and the packing structure changes caused by the resin flow promote the shrinkage and deformation of the part. During the coated sand heating, the resin on the surface flowing to the contact points of the particles forms the resin neck and causes particles to pack close to each other. In this work, the diameters of the coated ceramsite sand before and after heating were measured based on in-situ experimental observations with image measuring apparatus and blue laser, to obtain the relationship between resin coating thickness and the particle diameter. The particle packing model was established to describe the particles' achievement of a stable state one by one. A re-packing simulation was then performed after reducing the particle diameter according to the resin coating thickness, to obtain the shrinkage ratios at different particle size distributions. It was found that the resin coating thickness increased from 0.8 to 2.3 μm as the particle diameter increased from 107 to 500 μm, for the coated ceramsite sand with the resin content of 2wt.%; the shrinkage ratio decreased first and then increased as the particle diameter increased. The experimental minimum shrinkage ratio was 3.28%, and the corresponding particle diameter was 300-375 μm, while the minimum shrinkage ratio obtained by simulation was 3.43%, and the corresponding particle diameter was 214-300 μm. After mixing the five groups proportionally, the shrinkage ratios of the simulation and experiment dropped to 2.81% and 3.04%, respectively, indicating the best results. [ABSTRACT FROM AUTHOR]

Regression analyses identified 'Growth Days' (an index expressing site moisture availability) as the only site variable contributing significantly to the prediction to wood density (R² = 0.57), whereas the model predicting grain angle included only 'Altitude' (R² = 0.60). These results surfaced during an investigative study to quantify various sources of variation in wood properties and to quantify the effect of a number of site factors on wood properties of Pinus patula grown in the Mpumalanga escarpment area of South Africa. For this purpose, 10 trees were sampled from each of 17 diverse sites for wood property analyses. The effects of site, distance from the pith and differences between trees within site on wood density, transverse shrinkage, grain angle and dynamic modulus of elasticity were investigated. The site factors considered included a wide variety of soil and climatic factors. The effect of radial distance from the pith and differences between individual trees within sites were highly significant, accounting for most of the variation in wood properties. Although the effects of a number of site factors were statistically significant, they generally explained relatively small but important variation in wood properties among sites. The study not only quantified the effects of important sources of variation on a few key wood properties, but it also revealed that the extent of differences between sites can be explained in terms of some specific site factors. It is envisaged that the results will contribute significantly towards the refinement of current forest site classification systems for improved decision-making with respect to wood quality in intensively managed plantation systems. [ABSTRACT FROM AUTHOR]

The change in phase of the material from powder to liquid and then to solid is accompanied by a shrinkage in the metal volume, which becomes an inherent restraint during the selective laser melting (SLM) process. In order to improve the accuracy of SLM-processed parts, a three-factor, three-level, and multi-response experiment was designed; the influence of the process parameters like laser power, scanning speed, and layer thickness on the relative density and shrinkage ratio in Z-direction was investigated by the response surface methodology, and then optimized process parameters were derived from a multi-objective optimization. The result indicates that the laser power has a major effect on the shrinkage ratio in Z-direction, followed by scanning speed and then layer thickness. Then the dimension and shape accuracy of SLM-processed parts can be improved by the dimension compensation, which can help to limit the accuracy in Z-direction in ±0.8 %, and roundness of column and hole in ±1 %. Based on this study, the relationship between process parameters and accuracy in Z-direction of SLM-processed parts was revealed and thus, corresponding measures can be taken to improve the accuracy. [ABSTRACT FROM AUTHOR]

Highlights: [•] The inkjet-printed Ag nanoparticle lines were sintered by furnace sintering. [•] We trace the cross-sectional area shrinkage of inkjet-printed Ag nanoparticle lines. [•] Decrease of electric resistance of the line is proposed despite the shrinkage. [•] The Ag nanoparticle network enhanced the electrical property of the printed line. [Copyright &y& Elsevier]

[Display omitted] • Multi-scale deformations of activated carbon foam are observed. • Scale effect accounts for non-uniform deformation of activated carbon foam. • Effective transport properties are affected due to the deformation. • Closed-pore in porous skeleton plays a vital role in THM properties. • Prediction of shrinkage ratio can be used to optimize the micro-morphology. Deformation of activated carbon foam (ACF) during drying process is commonly encountered in adsorption, energy storage, chemical reaction, and other applications. In this work, a comprehensive study on the thermo-hydro-mechanical characteristics of ACF was performed by experimental investigation, numerical study, and artificial neural network (ANN) prediction. Multi-scale deformations of ACF induced by drying process were observed by experiments. A special "scale effect" occurred indicating that the pore structure of ACF experienced a non-uniform deformation. A 3D pore scale thermo-hydro-mechanical (THM) model was developed and solved by finite element method. Validation and comparisons between experiment and simulation revealed the mechanisms of deformations induced by drying. An artificial neural network trained on the fractal dimensions, closed pore ratio, and average pore throat diameter to provide a simple way to predict the shrinkage ratio and optimize the micro-morphology of ACF. The demarcation line which represents the stable shrinkage of ACF depends on the closed pore ratio and the average pore throat diameter to different extent. These insights support the efficient design and reliable utilization of ACF at multiple scales. [ABSTRACT FROM AUTHOR]

Abstract: The effects of some membrane preparation conditions on the characteristics and performance of poly(vinylidene fluoride)/polyethersulfone blend membranes were studied. Poly(vinylidene fluoride) (PVDF) and polyethersulfone (PES) were employed as base polymers. Four different solvents including dimethyl sulphoxide (DMSO), dimethyl formamide (DMF), 1-methyl-2-pyrrolidone (NMP) and dimethyl acetamide (DMAc) were used as the solvents. Polyvinylpyrrolidone (PVP) was used as pore-forming additive. The preparation variables in this work were sort of solvents, content proportion of PVDF/PES, and concentration of PVP. The flat-sheet membranes prepared by phase inversion were characterized by using scanning electron microscopy (SEM). Membrane performance was evaluated by shrinkage ratio, pure water flux and retention to bovine serum albumin (BSA). The shrinkage ratio of PVDF/PES blend membrane was much reduced when DMAc was used as a solvent. The pure water flux of blend membranes reaches the maximum and the retention to BSA reaches the minimum when the casting solution contains 1.5wt% PES and 5wt% PVP. [Copyright &y& Elsevier]

—Laser photolithography is a useful method for producing micro parts. One of the main factors affecting the accuracy of the polymer part is shrinkage during solidification. The shrinkage has an effect on the irradiated energy distribution on the polymer because the polymer is shrinking during the irradiation. The shrinkage and irradiated energy distribution cause manufacturing errors. The manufacturing accuracy when producing a micro part is calculated in this paper. Next, the polymer part is reinforced by addition of unidirectional whiskers. Whiskers are added to the liquid photopolymer and this mixture is placed in a vessel that has electrodes. By applying direct current (DC) to the electrodes, the axis of the whiskers in the liquid polymer is aligned along the direction of the electric field. The polymer is solidified by the irradiation of UV laser during the application of the direct current. The shrinkage ratio during the solidification is decreased and the tensile strength of the polymer part is increased by the addition of unidirectional whiskers. [ABSTRACT FROM AUTHOR]

The application of ultraviolet (UV)-curing coatings in precision devices is restricted because of their high shrinkage performance. In this study, hollow polyurethane acrylate (PUA) microspheres are filled into a mixed tripropylene glycol diacrylate (TPGDA) coating with different volume fractions to regulate shrinkage ratios of the coating, where hollow PUA microspheres with different diameters and thicknesses are synthesized using the microfluidics technology. The thickness-dependent mechanical properties of PUA thin films (the same thickness with the shell of each microsphere) are obtained by combining in-situ tensile and nanoindentation experiments with finite element (FE) method. The empirical formula between geometrical parameters (diameter, shell thickness, volume fraction) of hollow PUA microspheres and shrinkage ratios of the TPGDA coating filled with these PUA microspheres are derived using the present representative volume element (RVE) method. Checking against the results of UV-curing shrinkage experiments shows the current empirical formula has high accuracy. This study provides a physical insight into modulating their shrinkage ratios of different UV-curing materials. • An anti-shrinkage model of an UV-curing coating filled with hollow PUA microspheres is presented. • The thickness-dependent mechanical properties of PUA thin films are obtained by experiments and a FE method. • The empirical formulae of the shrinkage ratios of the coating are derived using RVE method. • This study provides a physical insight into modulating their shrinkage ratios of different UV-curing materials. [ABSTRACT FROM AUTHOR]

Understanding the flow process of cemented tailings backfill (CTB) is important for successful pumping into underground stopes. This study examines the effects of solid content (SC), cement/tailings (c/t) ratio, and curing time (CT) on rheological and mechanical properties of CTB mixes. The slurry concentration of the mixes was 65, 67, and 69 wt. %, with c/t ratios ranging from 1:4 to 1:20. Unconfined compressive strength (UCS) tests were performed on hardened CTB mixes after curing 3, 7, and 28 days. The rheological properties of CTB slurries are mainly related to SC. The yield stress and viscosity of fresh mixes increase with increasing SC, but the pipeline resistance loss (PRL) also increases with increasing SC. According to the analysis of variance, the SC and flow rate are the most significant parameters which greatly affect the PRL performance. The c/t and CT parameters are the most significant parameters for affecting the shrinkage rate. The findings offer a reference for theoretical optimization for mine filling systems of similar type. [ABSTRACT FROM AUTHOR]

• Effect of fibrillated PTFE and PTFE particles on TPU foam was compared. • Rheological behavior of TPU/PTFE composites under CO 2 was investigated. • Fibrillated PTFE decreased shrinkage ratio of TPU foam to some extent. • 0.5 wt% fibrillated PTFE enhanced compressive strength of TPU foam by 100%. • PTFE made TPU change from hydrophilic to hydrophobic. Effects of different morphologies and contents of polytetrafluorethylene (PTFE) on the foaming and rheological behavior of thermoplastic polyurethane (TPU) and mechanical properties of TPU/PTFE composite foams were investigated. High-pressure rheological test results showed that fibrillated PTFE had a more significant effect on the reinforcement of TPU than PTFE particles. In addition, the TPU/fibrillated PTFE composite foam exhibited good compression recovery properties, and its compressive strength was 109% that of TPU/PTFE composite foam with PTFE particles. Furthermore, with increasing PTFE content, TPU/PTFE foams exhibited higher compressive strength and good compression recovery properties. Retention of maximum stress was approximately 90%, and the strain recovery rate of the TPU/PTFE foam was approximately 80% of the initial value after 50 compression cycles. Moreover, the shrinkage ratio of the TPU foam decreased with increasing PTFE content, and fibrillated PTFE enhanced the hydrophobicity of TPU. [ABSTRACT FROM AUTHOR]

• This method exhibits a good result of quality prediction of dried carrot slices. • A new multispectral image system is proposed for quality detection of carrot slices. • This method can detect the quality of dried carrots quickly and non destructively. Carrot has high nutritional value and health-promoting effects and is popular among consumers. Real-time quality detection of dried carrot slices allows producers to adjust the process parameters of the drying device in time, thereby ensuring the final product quality and realizing energy conservation. Traditional methods of detecting moisture content and shrinkage ratio usually require a long measurement time, which is difficult to meet the needs of practical application. This investigated a rapid method based on a novel multispectral imaging system for acquiring multispectral images of samples in 25 wavebands over the spectral region between 675 and 975 nm at one time to detect moisture content and shrinkage ratio of dried carrot slices. The multispectral images of 600 carrot slice samples, which were dried at different times, were acquired using the multispectral imaging system. After extracting the spectral and GLCM features of the samples, prediction models were developed based on partial-least squares regression (PLSR) and least squares-support vector machines (LS-SVM) by using different feature combinations. Compared with PLSR models, LS-SVM models achieved better detection accuracy for moisture content and shrinkage ratio. The LS-SVM model obtained the following best results: coefficient of determination in prediction (Rp) = 0.942, root mean square error of prediction (RMSEP) = 0.0808%, and residual predictive deviation (RPD) = 2.636 for shrinkage ratio as well as Rp = 0.953, RMSEP = 0.0902%, and RPD = 3.271 for moisture content under static condition (without movement). The detection accuracy decreased with increasing movement speed of the test sample. When the movement speed of the sample was lower than 30 mm/s, the moisture content detected achieved satisfactory accuracy, with Rp = 0.941, RMSEP = 0.0981%, and RPD = 3.001. The novel multispectral imaging system shows potential for real-time detection of moisture and shrinkage of products during drying. [ABSTRACT FROM AUTHOR]