A Production Planning Model for Make-to-Order Foundry Flow Shop with Capacity Constraint

The mode of production in the modern manufacturing enterprise mainly prefers to MTO (Make-to-Order); how to reasonably arrange the production plan has become a very common and urgent problem for enterprises’ managers to improve inner production reformation in the competitive market environment. In this paper, a mathematical model of production planning is proposed to maximize the profit with capacity constraint. Four kinds of cost factors (material cost, process cost, delay cost, and facility occupy cost) are considered in the proposed model. Different factors not only result in different profit but also result in different satisfaction degrees of customers. Particularly, the delay cost and facility occupy cost cannot reach the minimum at the same time; the two objectives are interactional. This paper presents a mathematical model based on the actual production process of a foundry flow shop. An improved genetic algorithm (IGA) is proposed to solve the biobjective problem of the model. Also, the gene encoding and decoding, the definition of fitness function, and genetic operators have been illustrated. In addition, the proposed algorithm is used to solve the production planning problem of a foundry flow shop in a casting enterprise. And comparisons with other recently published algorithms show the efficiency and effectiveness of the proposed algorithm

Commitment of chondrogenic precursors of the avian scapula takes place after epithelial-mesenchymal transition of the dermomyotome

<p>Abstract</p> <p>Background</p> <p>Cells of the epithelially organised dermomyotome are traditionally believed to give rise to skeletal muscle and dermis. We have previously shown that the dermomyotome can undergo epithelial-mesenchymal transition (EMT) and give rise to chondrogenic cells, which go on to form the scapula blade in birds. At present we have little understanding regarding the issue of when the chondrogenic fate of dermomyotomal cells is determined. Using quail-chick grafting experiments, we investigated whether scapula precursor cells are committed to a chondrogenic fate while in an epithelial state or whether commitment is established after EMT.</p> <p>Results</p> <p>We show that the hypaxial dermomyotome, which normally forms the scapula, does not generate cartilaginous tissue after it is grafted to the epaxial domain. In contrast engraftment of the epaxial dermomyotome to the hypaxial domain gives rise to scapula-like cartilage. However, the hypaxial sub-ectodermal mesenchyme (SEM), which originates from the hypaxial dermomyotome after EMT, generates cartilaginous elements in the epaxial domain, whereas in reciprocal grafting experiments, the epaxial SEM cannot form cartilage in the hypaxial domain.</p> <p>Conclusions</p> <p>We suggest that the epithelial cells of the dermomyotome are not committed to the chondrogenic lineage. Commitment to this lineage occurs after it has undergone EMT to form the sub-ectodermal mesenchyme.</p

A New Aerodynamic Optimization Method with the Consideration of Dynamic Stability

Dynamic stability is significantly important for flying quality evaluation and control system design of the advanced aircraft, and it should be considered in the initial aerodynamic design process. However, most of the conventional aerodynamic optimizations only focus on static performances and the dynamic motion has never been included. In this study, a new optimization method considering both dynamic stability and general lift-to-drag ratio performance has been developed. First, the longitudinal combined dynamic derivative based on the small amplitude oscillation method is calculated. Then, combined with the PSO (particle swarm optimization) algorithm, a dynamic stability derivative that must not be decreased is added to the constraints of optimization and the lift-drag ratio is chosen as the optimization objective. Finally, a new aerodynamic optimization method can be built. We take NACA0012 as an example to validate this method. The results show that the dynamic derivative calculation method is effective and conventional optimization design can significantly improve the lift-drag ratio. However, the dynamic stability is enormously changed at the same time. By contrast, the new optimization method can improve the lift-drag performance while maintaining the dynamic stability

Performance Simulation and Fused Filament Fabrication Modeling of the Wave-Absorbing Structure of Conductive Multi-Walled Carbon Nanotube/Polyamide 12 Composite

Fused filament fabrication (FFF) is a reliable method for fabricating structured electromagnetic wave (EMW) absorbers from absorbing materials. In this study, polymer-matrix composites were prepared using polyamide 12 (PA12) which was recovered from selective laser sintering (SLS) as the substrate and multi-walled carbon nanotubes (MWCNT) as the filler. The CST software is used for simulation calculation and study of electromagnetic wave absorption characteristics of composite materials. After that, based on the obtained parameters and results, modeling was carried out, and finally, EMW absorbers with various microstructures were fabricated by FFF. For the honeycomb structure sample, when the side length is 5 mm and the height is 2 mm, the minimum return loss (RL) of the composite at 15.81 GHz is −14.69 dB, and the maximum effective absorption bandwidth is 1.93 GHz. These values are consistent with the simulation results. The pyramid structure has better absorbing performance than plate structure and honeycomb structure. According to simulation calculations, the pyramid structure shows the best performance at an angle of 28°. The absorption performance of the printed pyramid structure sections exceeded the simulated values, with effective absorption bandwidth (EAB) reaching all frequencies from 2 to 18 GHz, with a minimum return loss of −47.22 dB at 8.24 GHz

Numerical Simulation on Excluding Foreign Objects from Engine Inlet of Turboprop Aircraft

Hail, ice and other foreign matters are sucked into the intake port and then enter the engine, which can easily lead the engine performance degradation or stop, threatening the flight safety. Therefore, it is of great significance to analyze the exhaust characteristics of the channel beside the intake port of turboprop aircraft. According to the airworthiness criterion, two kinds of foreign bodies, hail and ice, are analyzed to determine their geometry, mass and initial attitude. By means of CFD and 6DOF method, the movement and exclusion characteristics of foreign bodies in the main engine inlet of a new turboprop regional aircraft are simulated. Further coupling the LS-DYNA software to simulate and analyze the collision problems encountered in the exclusion. A numerical simulation method for the removal of foreign matter from the intake port of turboprop engine is established. The results show that once the foreign body collides with the wall, it will break up into some small pieces. The energy loss is less threatening to the engine. Whether it enters the main engine or the side channel, it can be considered to be eliminated; However, the ice in the ice area of the lower wall is likely to enter the main engine directly, which may cause serious impact, so it needs to be focused on

Cathode materials of metal-ion batteries for low-temperature applications

Energy storage devices have been developed greatly in recent years. Developing forward, they are expected to operate stably in electric vehicles, electric grids, military equipment, and aerospaces in various climates. Unfortunately, these areas require batteries to be repeatedly and periodically exposed to sub-zero temperatures, even extremely low temperatures (-40 degrees C or lower). The low temperature reduces the kinetics of all the activation processes of the batteries, leading to increased impedance and polarization, and loss of battery energy and power, thus restricting their performance. Developing new cathode materials is one of the main strategies to alleviate the low-temperature restrictions. A conventional lithium-ion battery is the most attractive system, which is more adaptive to the practical low-temperature application now. Sodium ion batteries, magnesium-ion batteries, and zinc-ion batteries, which have the advantages of low cost and high safety, are considered potential substitutes for lithium-ion batteries, the electrochemical performance of these batteries at low-temperature has been conducted extensively. This review provides an overview of lithium-ion batteries, sodium-ion batteries, magnesium-ion batteries, and zinc-ion batteries that can work normally in low-temperature environments, with emphasis on various high-energy cathode materials, mainly including polyanionic compounds, layered oxides, spinel oxides, Prussian blue, and Prussian blue analogs. Specifically, we propose how the conventional low-temperature charge-transfer resistance can be overcome. However, these chemistries also present their own unique challenges at low temperatures. This article discusses the advantages and disadvantages of these materials, as well as the main challenges and strategies for applying them to batteries at low temperatures so that the batteries can still discharge efficiently.(c) 2022 Elsevier B.V. All rights reserved

Cathode materials of metal-ion batteries for low-temperature applications

Energy storage devices have been developed greatly in recent years. Developing forward, they are expected to operate stably in electric vehicles, electric grids, military equipment, and aerospaces in various climates. Unfortunately, these areas require batteries to be repeatedly and periodically exposed to sub-zero temperatures, even extremely low temperatures (-40 degrees C or lower). The low temperature reduces the kinetics of all the activation processes of the batteries, leading to increased impedance and polarization, and loss of battery energy and power, thus restricting their performance. Developing new cathode materials is one of the main strategies to alleviate the low-temperature restrictions. A conventional lithium-ion battery is the most attractive system, which is more adaptive to the practical low-temperature application now. Sodium ion batteries, magnesium-ion batteries, and zinc-ion batteries, which have the advantages of low cost and high safety, are considered potential substitutes for lithium-ion batteries, the electrochemical performance of these batteries at low-temperature has been conducted extensively. This review provides an overview of lithium-ion batteries, sodium-ion batteries, magnesium-ion batteries, and zinc-ion batteries that can work normally in low-temperature environments, with emphasis on various high-energy cathode materials, mainly including polyanionic compounds, layered oxides, spinel oxides, Prussian blue, and Prussian blue analogs. Specifically, we propose how the conventional low-temperature charge-transfer resistance can be overcome. However, these chemistries also present their own unique challenges at low temperatures. This article discusses the advantages and disadvantages of these materials, as well as the main challenges and strategies for applying them to batteries at low temperatures so that the batteries can still discharge efficiently.(c) 2022 Elsevier B.V. All rights reserved

Oil Spill Monitoring of Shipborne Radar Image Features Using SVM and Local Adaptive Threshold

In the case of marine accidents, monitoring marine oil spills can provide an important basis for identifying liabilities and assessing the damage. Shipborne radar can ensure large-scale, real-time monitoring, in all weather, with high-resolution. It therefore has the potential for broad applications in oil spill monitoring. Considering the original gray-scale image from the shipborne radar acquired in the case of the Dalian 7.16 oil spill accident, a complete oil spill detection method is proposed. Firstly, the co-frequency interferences and speckles in the original image are eliminated by preprocessing. Secondly, the wave information is classified using a support vector machine (SVM), and the effective wave monitoring area is generated according to the gray distribution matrix. Finally, oil spills are detected by a local adaptive threshold and displayed on an electronic chart based on geographic information system (GIS). The results show that the SVM can extract the effective wave information from the original shipborne radar image, and the local adaptive threshold method has strong applicability for oil film segmentation. This method can provide a technical basis for real-time cleaning and liability determination in oil spill accidents

Medium-Entropy-Alloy FeCoNi Enables Lithium-Sulfur Batteries with Superb Low-Temperature Performance

Lithium-sulfur battery suffers from sluggish kinetics at low temperatures, resulting in serious polarization and reduced capacity. Here, this work introduces medium-entropy-alloy FeCoNi as catalysts and carbon nanofibers (CNFs) as hosts. FeCoNi nanoparticles are in suit synthesized in cotton-derived CNFs. FeCoNi with atomic-level mixing of each element can effectively modulate lithium polysulfides (LiPSs), multiple components making them promising to catalyze more LiPSs species. The higher configurational entropy endows FeCoNi@CNFs with extraordinary electrochemical activity, corrosion resistance, and mechanical properties. The fractal structure of CNFs provides a large specific surface area, leaving room for volume expansion and Li2S accumulation, facilitating electrolyte wetting. The unique 3D conductive network structure can suppress the shuttle effect by physicochemical adsorption of LiPSs. This work systematically evaluates the performance of the obtained Li2S6/FeCoNi@CNFs electrode. The initial discharge capacity of Li2S6/FeCoNi@CNFs reaches 1670.8 mAh g(-1) at 0.1 C under -20 degrees C. After 100 cycles at 0.2 C, the capacity decreases from 1462.3 to 1250.1 mAh g(-1). Notably, even under -40 degrees C at 0.1 C, the initial discharge capacity of Li2S6/FeCoNi@CNFs still reaches 1202.8 mAh g(-1). After 100 cycles at 0.2 C, the capacity retention rate is 50%. This work has important implications for the development of low-temperature Li-S batteries