Preface： theory, methods, and applications of mesoscopic modeling

With increasing attention to complex fluids and soft matter,we have witnessed a fastgrowing research in mesoscopic modeling and simulation in the past decades.The development of mesoscopic methods offers many potential opportunities as well as challenges in modeling of complex materials for diverse applications.Despite significant progress in the past decade,mesoscopic methods are still under development.New formulation in the models,novel theo-

An Application of the Modified Shear Lag Model to Study the Influence of Thermal Residual Stresses on the Stiffness and Yield Strength of Short Fiber Reinforced Metal Matrix Composites

The modified shear lag model proposed recently was applied to calculate thermal residual stresses and subsequent stress distributions under tensile and compressive loadings. The expressions for the elastic moduli and the yield strengths under tensile and compressive loadings were derived which take account of thermal residual stresses. The asymmetries in the elastic modulus and the yield strength were interpreted using the derived expressions and the obtained results of the stress calculations. The model predictions have exhibited good agreements with the experimental results and also with the other theoretical

Fertilization strategy and application model using a centrifugal variable-rate fertilizer spreader

With the sustainable development of precision agriculture and the steady progress of variable-rate fertilization technology,the centrifugal variable-rate fertilizer spreader has attracted research attention due to its lower incidence of crush damage,high efficiency,and low cost.To improve fertilization accuracy and uniformity,spreading performance tests were conducted using this spreader in accordance with the test methods specified in ISO 5690 and ASAE S341.2,in which particle mass was weighed in a two-dimensional matrix of collection boxes.The effects of fertilization strategies that control the feed gate flow rate and the disc rotation speed on particle distribution,and application rate per unit area and effective swath width,were investigated.A variable-rate fertilization model was developed by analyzing the variation characteristics resulting from an increasing and decreasing application rate,and field experiments were conducted to verify its accuracy.The results indicated that when the feed gate flow rate was 300 g/s,the mean application rate was 26.47 g,the standard deviation is 2.81,and the coefficient of variation of particle distribution is at its minimum value of 14.25%.When the disc rotation speed was 600 r/min,the fertilizer was most evenly distributed with a coefficient of variation of 13.86%,and an average effective spreader swath width of 24.51 m.The proposed variable-rate fertilization model showed a high fitting degree with an S-shaped function curve for both increasing and decreasing distribution rates and the yielding coefficients of determination were more than 0.82 and 0.71,respectively.The average error between the model predictions and the test results was 9.47%,and the coefficients of determination for the increasing and decreasing distribution rates were 0.91 and 0.82,respectively,which confirmed the accuracy of the proposed variable-rate fertilization model.This investigation provided a theoretical basis for traditional empirical fertilization using centrifugal variable-rate fertilizer spreaders,and guides the selection of a multiple trajectory,variable-rate fertilization strategy.

An Experimentally Validated SOA Model for High-Bit Rate System Applications

A comprehensive model of the Semiconductor Optical Amplifier with experimental validation result is presented. This model accounts for various physical behavior of the device which is necessary for high bit-rate system application.

The modelling and application of cross-scale human behavior in realizing the shop-floor digital twin[version 1;peer review:1 approved with reservations,1 not approved]

The digital twin shop-floor has received much attention from the manufacturing industry as it is an important way to upgrade the shop-floor digitally and intelligently.As a key part of the shop-floor,humans'high autonomy and uncertainty leads to the difficulty in digital twin modeling of human behavior.Therefore,the modeling system for cross-scale human behavior in digital twin shop-floors was developed,powered by the data fusion of macro-behavior and micro-behavior virtual models.Shop-floor human macro-behavior mainly refers to the role of the human and their real-time position.Shop-floor micro-behavior mainly refers to real-time human limb posture and production behavior at their workstation.In this study,we reviewed and summarized a set of theoretical systems for cross-scale human behavior modeling in digital twin shop-floors.Based on this theoretical system,we then reviewed modeling theory and technology from macro-behavior and micro-behavior aspects to analyze the research status of shop-floor human behavior modeling.Lastly,we discuss and offer opinion on the application of cross-scale human behavior modeling in digital twin shop-floors.Cross-scale human behavior modeling is the key for realizing closed-loop interactive drive of human behavior in digital twin shop-floors.

STEP AP 242 Managed Model-based 3D Engineering:An Application Towards the Automation of Fixture Planning

Fixture design and planning is one of the most important manufacturing activities, playing a pivotal role in deciding the lead time for product development. Fixture design, which affects the part-quality in terms of geometric accuracy and surface finish, can be enhanced by using the product manufacturing information(PMI) stored in the neutral standard for the exchange of product model data(STEP) file, thereby integrating design and manufacturing. The present paper proposes a unique fixture design approach, to extract the geometry information from STEP application protocol(AP) 242 files of computer aided design(CAD) models, for providing automatic suggestions of locator positions and clamping surfaces. Automatic feature extraction software "FiXplan", developed using the programming language C#, is used to extract the part feature, dimension and geometry information. The information from the STEP AP 242 file is deduced using geometric reasoning techniques, which in turn is utilized for fixture planning. The developed software is observed to be adept in identifying the primary, secondary, and tertiary locating faces and locator position configurations of prismatic components. Structural analysis of the prismatic part under different locator positions was performed using commercial finite element method software, ABAQUS, and the optimized locator position was identified on the basis of minimum deformation of the workpiece.The area-ratio(base locator enclosed area(%)/work piece base area(%)) for the ideal locator configuration was observed as 33%. Experiments were conducted on a prismatic workpiece using a specially designed fixture, for different locator configurations. The surface roughness and waviness of the machined surfaces were analysed using an Alicona non-contact optical profilometer. The best surface characteristics were obtained for the surface machined under the ideal locator positions having an area-ratio of 33%, thus validating the predicted numerical results. The efficiency, capability and applicability of the developed software is demonstrated for the finishing operation of a sensor cover – a typical prismatic component having applications in the naval industry, under different locator configurations.The best results were obtained under the proposed ideal locator configuration of area-ratio 33%.

Modelling of grinding mechanics:A review

Grinding is one of the most widely used material removal methods at the end of many process chains.Grinding force is related to almost all grinding parameters,which has a great influence on material removal rate,dimensional and shape accuracy,surface and subsurface integrity,thermodynamics,dynamics,wheel durability,and machining system deformation.Considering that grinding force is related to almost all grinding parameters,grinding force can be used to detect grinding wheel wear,energy calculation,chatter suppression,force control and grinding process simulation.Accurate prediction of grinding forces is important for optimizing grinding parameters and the structure of grinding machines and fixtures.Although there are substantial research papers on grinding mechanics,a comprehensive review on the modeling of grinding mechanics is still absent from the literature.To fill this gap,this work reviews and introduces theoretical methods and applications of mechanics in grinding from the aspects of modeling principles,limitations and possible future trendencies.

Development of an ionic polymer-metal composite stepper motor using a novel actuator model

A novel ionic polymer–metal composite(IPMC)actuated stepper motor was developed in order to demonstrate an innovative design process for complete IPMC systems.The motor was developed by utilizing a novel model for IPMC actuators integrated with the complete mechanical model of the motor.The dynamic,nonlinear IPMC model can accurately predict the displacement and force actuation in air for a large range of input voltages as well as accounting for interactions with mechanical systems and external loads.By integrating this geometrically scalable IPMC model with a mechanical model of the motor mechanism an appropriate size IPMC strip has been chosen to achieve the required motor specifications.The entire integrated system has been simulated and its performance verified.The system has been built and the experimental results validated to show that the motor works as simulated and can indeed achieve continuous 360
rotation,similar to conventional motors.This has proven that the model is an indispensable design tool for integrated IPMC actuators into real systems.This newly developed system has demonstrated the complete design process for smart material actuator systems,representing a large step forward and aiding in the progression of IPMCs towards wide acceptance as replacements for traditional actuators.