With the increasing peak torque of the in-wheel motor, the tire slip energy dissipation becomes as considerable as the motor energy loss. The actuation red
Using nanomaterials is a new method to improve concrete material, and graphene or its derivatives are currently the most attractive nanomaterials. This paper aims to experimentally evaluate the effects of graphene sulfonate nanosheets (GSNSs) on physical, mechanical, and thermal properties of sacrificial concrete. The microstructure, porosity, compressive strength, thermal analysis, coefficient of thermal expansion, thermal diffusivity and ablation behaviour of sacrificial concrete with different contents of GSNSs before and during exposure to various temperatures up to 1000 °C were comprehensively investigated. A new experimental apparatus was proposed and used to measure the compressive strength of sacrificial concrete during elevated temperature exposure. It was found that, (1) the compressive strength, thermal diffusivity, and decomposition enthalpy of sacrificial concrete increased by 10.14–23.11%, 6.51–27.66%, and 7.48%, respectively, when adding 0.1 wt% GSNSs; (2) the porosity and ablation velocity of sacrificial concrete reduced by 2.00–6.00% and 7.48%, respectively, due to the incorporation of GSNSs.
Schwarz's form is fundamental and effective in constructing Liapuaov functions, in proving the Hurwitz criterion, and in evaluating performance measures in system analysis. However, the procedures developed thus far for obtaining the Schwarz form are complicated. This paper establishes a basic transformation matrix by which a phase-variable form is easily converted into a Schwarz form. When the new transformation matrix is used, Kalman-Bertram's Liapunov function is simplified and Ralston's symmetric matrix formulation of the Hurwitz criterion is derived in a completely different but much more sophisticated way. Finally, to the authors' knowledge, this is the first time that practical use has been made of the second, third, etc., columns of Routh's array.
Ultra-high-performance concrete (UHPC) has promising applications in civil engineering. However, the elastic modulus of UHPC is relatively low compared with its compressive strength, which may result in insufficient stiffness in service. This work was carried out to explore the feasibility of producing UHPC with high elastic modulus by nano-Al2O3 (NA). Based on particle densely packing theory, the initial mixture of UHPC was designed via the modified Andreasen and Andersen model. An experimental investigation was conducted to systematically examine the effects of NA on different properties of UHPC, including its fluidity, mechanical properties, durability, and microstructure. It was found that: (1) Compared with UHPC without NA, the flexural strength, compressive strength, and elastic modulus of UHPC were improved by 7.38-16.87%, 4.08-20.58%, and 2.89-14.08%, respectively, because of the incorporation of NA; (2) the addition of NA had a prohibiting impact on the threshold pore diameter and porosity of UHPC, which suggested that NA could be conducive to its pore structure; (3) the incorporation of NA led to a decline of 2.9-11.76% in the dry shrinkage of UHPC, which suggested that incorporating NA in a proper amount could reduce the risk of cracking and alleviate the dry shrinkage of UHPC; (4) the optimal amount of NA in UHPC was 1.0%, considering the effects of NA on workability, mechanical properties, microstructure, and the durability of UHPC.
The hard roller and soft roller are alternately arranged in the inking system of offset press. The ink vibrator is a hard roller which transmits the motion to the ink distributing roller. In order to analyze the motion mechanism of the ink roller, a model of an ink distributing roller and an ink vibrator is built up by using the software ANSYS. After the simulation of the motion, the force on the contact area of the ink distributing roller and the rotation speed of both rollers are analyzed. The result is that the ink distributing roller rotates with tangential force on the contact area and this force increases together with the rotation speed. When the two rollers rotate, the tangential elastic deformation is caused by the tangential force on contact area, and the radial deformation of the ink distributing roller is caused by the pressure. It leads to a relative sliding of the two rollers, which is mainly influenced by the rotation speed of ink vibrator and the radial deformation of ink distributing roller. Meanwhile, to verify the accuracy of the analysis, the rotation speed of the two rollers and the deformation of the ink distributing roller have been measured on a printability tester and then compared with the results of simulation. The analysis of the motion mechanism is very important to the study of printing color quality control.
Ultra-high-performance concrete (UHPC) has been used as an advanced construction material in civil engineering because of its excellent mechanical properties and durability. However, with the depletion of the raw material (river sand) used for preparing UHPC, it is imperative to find a replacement material. Recycled sand is an alternative raw material for preparing UHPC, but it degrades the performance. In this study, we investigated the use of graphene oxide (GO) as an additive for enhancing the properties of UHPC prepared from recycled sand. The primary objective was to investigate the effects of GO on the mechanical properties and durability of the UHPC at different concentrations. Additionally, the impact of the GO additive on the microstructure of the UHPC prepared from recycled sand was analysed at different mixing concentrations. The addition of GO resulted in the following: (1) The porosity of the UHPC prepared from recycled sand was reduced by 4.45–11.35%; (2) the compressive strength, flexural strength, splitting tensile strength, and elastic modulus of the UHPC prepared from recycled sand were enhanced by 8.24–16.83%, 11.26–26.62%, 15.63–29.54%, and 5.84–12.25%, respectively; (3) the resistance of the UHPC to penetration of chloride ions increased, and the freeze–thaw resistance improved; (4) the optimum mixing concentration of GO in the UHPC was determined to be 0.05 wt.%, according to a comprehensive analysis of its effects on the microstructure, mechanical properties, and durability of the UHPC. The findings of this study provide important guidance for the utilisation of recycled sand resources.
In this paper, taking an intelligent electric vehicle as the research object, mathematical models are firstly built for calculating the percentage of lithium-ion battery capacity loss and the internal resistance increase. Based on the model established, a control-oriented battery life model is derived using to calculate the battery capacity loss during an acceleration process. Then, a velocity trajectory optimization framework is presented to minimize the battery aging life for intelligent EVs during an acceleration process and the problem is solved by SQP algorithm. Finally, according to the simulation results, it can be concluded that the energy consumption per meter is 5.50kJ/m from 0 to 100km/h within 10s. The effect on battery capacity is much greater than that on battery internal resistance during the acceleration process.
Ultra-high-performance concrete (UHPC) has attracted wide interests in civil engineering but it has large deadweight, which limits its application in light
Spinel Li4Mn5O12 was prepared by a sol–gel method. The manganese oxide and activated carbon composite (MnO2-AC) were prepared by a method in which KM
High-Performance Concrete (HPC) is characterized by its densely structured microstructure, providing superior strength and impermeability compared to conventional concretes, but it remains susceptible to spalling when exposed to high temperatures. To address this limitation, the present study focuses on the formulation of High-Performance Lightweight Concrete (HPLC) by incorporating sisal fiber and steel fiber, aiming to mitigate the tendency for spalling under elevated thermal conditions commonly observed in HPC. The present research employed the Modified Andreasen & Andersen particle packing model to optimize the initial mixture proportions for HPLC. This study comprehensively examined the effects of varying sisal fiber concentrations on the workability, mechanical properties, durability, microstructure, and thermal spalling of HPLC. Key findings from the experimental investigation indicate that HPLC developed in this study exhibits high compressive strength, with the most notable performance observed at a sisal fiber volume of 2.0 %, resulting in an apparent density of 1876 kg/m³ and a compressive strength of 110.1 MPa. Incorporation of sisal fiber at a volume of 1.0 % significantly enhances the mechanical properties of HPLC, as evidenced by increases of 11.6 % in flexural strength, 11.9 % in compressive strength, 6.5 % in elastic modulus, and 25.8 % in impact resistance. Additionally, at the same fiber inclusion rate, improvements are noted in the material’s resistance to chloride ion penetration and drying shrinkage, with reductions of 4.9 % and 7.3 %, respectively. Adequate amounts of sisal fiber also improve the gel pore structure of HPLC matrix. The thermal degradation of sisal fibers at high temperatures creates channels for steam egress, reducing vapor pressure within HPLC and thereby enhancing its resistance to thermal spalling. A holistic examination of the influence of sisal fibers on the mechanical performance, micromorphology, and thermal endurance of HPLC indicates that the optimal sisal fiber content is established at 1.0 % by volume. Future research could concentrate on optimizing fiber types and compositions, exploring hybrid fiber options, and evaluating long-term durability under diverse environmental stresses to broaden the scope of applications.
The H9N2 avian influenza virus (AIV) is difficult to prevent and control because of its low pathogenicity and frequent mutation. In a previous study, the HA (hemagglutinin) protein of H9N2 was expressed in a rice endosperm reactor and prepared into a subunit vaccine to immunize chickens and mice, both of which exhibited a good immunity effect. The results of the intermediate tests of the transgenic strains (AIV-1 and AIV-3) showed that the HA gene can be stably expressed. Agronomic traits, such as plant height and number of grains, were significantly optimized in the transgenic strains. Moreover, no exogenous HA genes were found in the leaves of the weeds, and it was initially determined that there was no risk of gene drift. This study provides key technical support for the commercialization of plant subunit vaccines for avian influenza viruses.
Municipal Solid Waste Incineration Fly Ash (MSWI-FA) contains heavy metals, dioxins, and hazardous substances, making it a hazardous waste. The application of solidification/stabilization (S/S) treatment using chelating agents is widespread due to its high efficiency. However, this treatment is associated with high solidification costs. In this study, an attempt was made to solidify MSWI-FA using sulphoaluminate cement (SAC). Firstly, the effects of varying substitution rates of MSWI-FA on the workability, mechanical properties, durability and heat of hydration of ecological cement mortar (EM) were investigated. Secondly, the microstructure of the EM was investigated in order to ascertain the mechanism of solidification of the MSWI-FA via the SAC. Finally, the economic and environmental benefits of MSWI-FA as an alternative to SAC for the production of EM were evaluated using the material sustainability index. Results show that adding MSWI-FA decreases EM’s workability and mechanical properties, with compressive and flexural strength reductions between 6.87 % and 26.16 % and 5.74–36.74 %, respectively. Durability also declines, evidenced by increased drying shrinkage and chloride migration by 26.79–46.41 % and 11.05–48.19 %, respectively. A slower hydration rate reduces the total heat of hydration by 1.82–7.22 %, indicating lower cement hydration. The porosity and pore size increase, deteriorating the pore structure. However, SAC effectively solidifies heavy metals, with leaching rates for lead and zinc significantly below national standards. A 15 % substitution rate of MSWI-FA reduces energy consumption, carbon emissions, and production costs by 14.90 %, 14.63 %, and 4.03 %, respectively, demonstrating notable economic and environmental advantages.
With the current energy environment background and development of the electrification of the automotive industry, a comprehensive economic indicator, in which the battery aging is further considered on the basis of conventional energy consumption, is proposed to research the energy optimization problem of two-speed electric vehicles. Firstly, a battery life model that adapts to vehicles under high dynamic conditions is introduced. Then, the speed optimal control problem of the two-speed electric vehicles in the acceleration–cruise–deceleration process is established and solved. Finally, the simulation results of two different performance indicators are contrasted and the performance improvement of the two-speed gearbox to the electric vehicles is analyzed. The simulation results under various working scenarios and driving cycles demonstrate that, compared with the conventional economic indicator considering the energy consumption only, the proposed economic indicator can significantly improve the battery life. In addition, it can also be seen that, compared with the one-speed electric vehicles, the application of a two-speed gearbox provides better performance from the aspects of battery aging saving and energy consumption.
The fabrication of high-performance cement-based materials has benefited greatly from the extensive use of graphene and its derivatives. This paper studies the effects of graphene sulfonate nanosheets (GSNSs) on sacrificial cement paste and mortar (the tested materials) and other siliceous sacrificial materials, especially their ablation behaviors and mechanical properties. Decomposition temperatures and differential scanning calorimetry were used to examine how different contents of GSNSs determines the corresponding decomposition enthalpy of the tested materials and their ablation behaviors. Molecular dynamics was also used to clarify the mechanism how the GSNSs work in the CSH (calcium silicate hydrated)/GSNSs composite to increase the resistance to high temperature. The experimental results show that: (1) the contents of GSNSs at 0.03 wt.%, 0.1 wt.%, and 0.3 wt.% brought an increase of 10.97%, 22.21%, and 17.56%, respectively, in the flexural strength of siliceous sacrificial mortar, and an increase of 1.92%, 9.16%, and 6.70% in its compressive strength; (2) the porosity of siliceous sacrificial mortar was decreased by 5.04%, 9.91%, and 7.13%, respectively, and the threshold pore diameter of siliceous sacrificial mortar was decreased by 13.06%, 35.39%, and 24.02%, when the contents of GSNSs were 0.03 wt.%, 0.1 wt.%, and 0.3 wt.%, respectively; (3) a decline of 11.16%, 28.50%, and 61.01% was found in the ablation velocity of siliceous sacrificial mortar, when the contents of GSNSs were 0.03 wt.%, 0.1 wt.%, and 0.3 wt.%, respectively; (4) when considering the ablation velocities and mechanical properties of siliceous sacrificial materials, 0.1 wt.% GSNSs was considered to be the optimal amount; (5) the GSNSs contribute to the reinforced effect of GSNSs on CSH gel through the grab of dissociated calcium and water molecules, and the chemical reaction with silicate tetrahedron to produce S–O–Si bonds. These results are expected to promoting the development of new kinds of siliceous sacrificial materials that contain GSNSs.
Ferro-siliceous concrete (FSC), as a sacrificial material, is used in European Pressurized Water Reactor. This paper presents an experimental investigation on the performance of FSC with and without polypropylene (PP) fibers subjected to elevated temperatures. Mechanical and physicochemical properties of FSCs were studied at both ambient and high temperatures. The occurrence of spalling, compressive strength, splitting tensile strength, mass loss, porosity, chemical composition, crystalline phase, and thermal analysis of FSCs before and after exposure to various temperatures (200, 400, 600, 800, and 1000°C) were comprehensively investigated. Ultrasonic pulse velocity (UPV) propagation in FSCs at different temperatures was determined by ultrasonic testing technique, and the relationships between strengths and UPV of FSCs were eventually obtained. The results indicated that, (1) the critical temperature range of FSCs was 400–600°C; (2) the compressive strength-UPV and splitting tensile strength-UPV relationships were Weibull distribution and exponential form, respectively; (3) compared to unheated FSCs, the porosity values were more than trebled after exposure to 1000°C.
In order to improve the printing quality and know the process of ink transferring well, ink flowing among ink rollers is simulated by using CFX. Firstly ink transferring characteristics between two rollers are analyzed. An experiment is carried out to test the accuracy of this simulation analysis. Then ink transferring characteristics among three and five rollers are analyzed respectively. The general characteristics of ink transferring among rollers are got by comparing the velocity of ink flowing, ink pressure and ink transfer ratio from those simulations. What is more, the accuracy of the simulation analysis is verified by experiment. And this research provides a reference to general characteristics of ink transferring in the actual printing process, and its important for the printing color quality control and has a better application prospect.
Galvanic corrosion between two different kinds of steel rebars is usually the case in practical engineering. Open circuit potential (OCP), linear polarization resistance (LPR), Tafel polarization, scanning vibrating electrode technique (SVET), scanning electron microscopy (SEM) and reflection digital holographic microscopy (DHM) were used to study the galvanic corrosion of a novel corrosion-resistant steel bar (CR) and low-carbon steel bar (LC) in simulated concrete pore solutions with different pH values and a chloride ion concentration of 5 mol L-1. The pH of the simulated concrete pore solution had a significant impact on the corrosion behaviour of CR and LC when they were in contact and were attacked by chloride ions. As the pH increased, the potential between CR and LC decreased and the driving force for the galvanic corrosion decreased. When the pH was 9.0, galvanic corrosion occurred on CR and LC at a high rate. CR developed local pitting corrosion, while LC mainly developed uniform corrosion, each with an apparent accumulation of corrosion products on the sample's surfaces. When the pH was 11.3, galvanic corrosion occurred when CR and LC were in contact. CR showed a relatively smooth surface, with only a small amount of pitting corrosion. In contrast, LC developed both pitting corrosion and uniform corrosion, and both apparent pitting corrosion and an accumulation of corrosion products on the sample surface were observed. When the pH was 13.6, there was no galvanic corrosion when CR and LC were in contact; the corrosion of CR and LC was mainly pitting corrosion. Therefore, for regions with chloride ion corrosion and severe carbonization, the galvanic corrosion between CR and LC cannot be ignored.
In this paper, the feasibility of using urea as an additive to prepare low exothermic concrete is studied. The effect of different urea contents (0%, 5%, 10%, 15%) urea on the hydration process and the microstructure of the cementitious materials were investigated systematically. The experimental results show that urea has an obvious retarding effect on the early hydration of cement. The curve of the hydration heat release was significantly reduced and delayed with the urea content increased. The early strength of the concrete decreased significantly. Urea has almost no effect on the compressive strength of concrete at 28 days of age. The actual water-to-binder ratio is lowered, and the hygroscopicity and recrystallization of urea are the main reasons for shrinkage reduction and even micro-expansion of concrete. Scanning electron microscope (SEM) and X-ray diffractometer (XRD) results show that urea does not change the cement hydration products. The total amount of chemically bound water and the degree of hydration of the sample show that urea has a greater inhibitory effect on early hydration of cement and less effect on hydration in a later stage. The results of mercury intrusion porosimetry (MIP) show that the total porosity of cement paste has a consistent trend with mechanical properties. When the content of urea in concrete exceeds 10%, white crystals appear inside of concrete. The FourierTransformInfraredSpectrometry (FT-IR), Differential thermal analysis (TG-DSC) and SEM result show that crystalline product is produced by urea crystallization.
