Electric traction is one of the most promising technologies that can lead to significant improvements in vehicle performance, energy utilization efficiency, and polluting emissions. Among several ...technologies, hybrid electric vehicle (HEV) traction is the most promising technology that has the advantages of high performance, high fuel efficiency, low emissions, and long operating range. Moreover, the technologies of all the component hardware are technically and markedly available. At present, almost all the major automotive manufacturers are developing hybrid electric vehicles, and some of them have marketed their productions, such as Toyota and Honda. This paper reviews the present technologies of HEVs in the range of drivetrain configuration, electric motor drives, and energy storages
This paper systematically discusses the design and control methodologies of a plug-in hybrid electric vehicle (PHEV). Design methodology is focused on battery energy and power capacity design. Two ...kinds of typical batteries, namely, NiMH and Li-ion, are discussed. Control strategies focus on all electric range and charge depletion range operations. In addition, a constrained engine on and off control strategy is discussed for charge-sustained operation. Simulation has been performed for an example passenger car. The simulation results indicate that a significant amount of fuel can be displaced by electric energy in typical urban driving.
Arable land health (ALH) and arable land productivity (ALP) are crucial indicators of agricultural ecological functionality and sustainability. The shift of grain‐producing regions in Northwest China ...has led to arable land degradation, which endangers both food production and sustainable development. Several studies have focused on arable land quantity, distribution, and regional features, but ALH and sustainable ALP have received little attention. For the first time, we investigated the spatio‐temporal distribution and coupling connection between ALH and ALP in Northwest China (NC) using soil health indicators. Our study revealed the following key findings: (1) A minimal dataset of 12 indicators can efficiently replace the total dataset to evaluate the arable land health index in NC. (2) Over the last 20 years, the high and sub‐high grades of ALH increased by 536.8% and 222.6%, respectively, with a shift toward the northwest. During the specified period, ALH with low health and underutilized grade decreased by 46.01% and 69.4%, respectively, primarily in Xinjiang and Inner Mongolia. At the county level, ALP increased by 26%, primarily in northern Xinjiang and southern Gansu. 71% of counties remained stable, while only 3% experienced a decline. (4) The relationship between ALH and ALP were divided into six coupled groups that form an inverted “U” shape. High‐production areas were generally strongly linked, while low‐production areas were weakly coupled. Over the last 20 years, NC has seen significant improvements in ALH, coinciding with an increase in ALP. However, in most cases, the relationship between ALH and ALP were negative or weak.
Highlights
Establish processing-composition-microstructure-property relationships governing binderless tungsten carbide (BTC).
Highlight the densification improving strategies and toughening methods ...for BTC.
Provide key challenges as well as the outlook for superior peformance associated with BTC.
WC-Co alloys have enjoyed great practical significance owing to their excellent properties during the past decades. Despite the advantages, however, recently there have been concerns about the challenges associated with the use of Co, i.e. price instability, toxicity and properties degeneration, which necessitates the fabrication of binderless tungsten carbide (BTC). On the other hand, BTC or BTC composites, none of them, to date has been commercialized and produced on an industrial scale, but only used to a limited extent for specialized applications, such as mechanical seals undergoing high burthen as well as high temperature electrical contacts. There are two challenges in developing BTC: fully densifying the sintered body together with achieving a high toughness. Thus, this review applies towards comprehensively summarize the current knowledge of sintering behavior, microstructure, and mechanical properties of BTC, highlighting the densification improving strategies as well as toughening methods, so as to provide reference for those who would like to enhance the performance of BTC with better reliability advancing them to further wide applications and prepare the material in a way that is environment friendly, harmless to human health and low in production cost. This paper shows that the fabrication of highly dense and high-performance BTC is economically and technically feasible. The properties of BTC can be tailored by judiciously selecting the chemical composition coupled with taking into careful account the effects of processing techniques and parameters.
•Elastic properties of titanium borides are calculated by first principles calculation.•Thermodynamical stability of titanium borides is analyzed.•Heat capacity and thermal expansion coefficient for ...titanium borides are calculated and compared.•Grüneisen parameters of titanium borides are calculated.
The anisotropic elastic and thermal expansions of the titanium borides (TiB2, Ti3B4, TiB_Pnma and TiB_Fm3¯m) are calculated from first-principles using density functional theory. All borides show different anisotropic elastic properties; the bulk, shear and Young’s moduli are consistent with those determined experimentally. The temperature dependence of thermal expansions is mainly caused by the restoration of thermal energy due to phonon excitations at low temperature. When the temperature is higher than 500K, the volumetric coefficient is increased linearly by increasing temperature. Meanwhile, the heat capacities of titanium borides are obtained based on the knowledge of thermal expansion coefficient and the elasticity, the calculations are in good agreement with the experiments.
The hot compression tests for Mo–3 vol.%Al
2
O
3
alloys were conducted on a Gleeble-1500D thermo-mechanical simulator in the temperatures range of 1000–1300 °C and strain rates range of 0.005–1 s
−1
.... The hot deformation behavior, mechanism associated with microstructure evolution of Mo–3 vol.%Al
2
O
3
alloys was investigated by electron backscattering diffraction analysis. Three types of stress–strain curves were analyzed by quantifying the work hardening rate. The deformation mechanism at 1000–1300 °C mainly included the plastic deformation of Mo–3 vol.%Al
2
O
3
alloy, as well as the dynamic recovery and recrystallization of Mo matrix. The modified Arrhenius, Modified Johnson–Cook and modified Zerilli–Armstrong constitutive equations were established and evaluated by the correlation coefficient (R
c
) and average absolute relative error (
e
¯
). The flow stress of Mo–3 vol.%Al
2
O
3
alloys could be well predicted by those three constitutive models, but modified Arrhenius constitutive model had a higher predicated accuracy.
Graphic Abstract
The hot deformation behavior, mechanism associated with microstructure evolution of Mo–3 vol.% Al
2
O
3
alloys has been investigated by EBSD analysis. Three types of stress–strain curves were analyzed by quantifying the work hardening rate. The deformation mechanism at 1000–1300 °C mainly included the plastic deformation of Mo–3 vol.% Al
2
O
3
alloy, as well as the dynamic recovery and recrystallization of Mo matrix. Moreover, modified Arrhenius constitutive model had a higher predicated accuracy for Mo–3 vol.% Al
2
O
3
alloys than modified JC and modified ZA constitutive models.
Effect of Co element on the microstructure and mechanical properties of maraging steel is studied and summarized. The microstructure and mechanical properties of five different compositions of ...maraging steels were characterized and tested in three heat treatment states, with the heat treatment schemes of homogenization treatment at 1300 °C × 10h, solution treatment at 800 °C × 2h, and aging treatment at 480 °C × 5h. The research has discovered that increasing the Co content in three different heat treatment states can lead to a reduction in the size of the original austenite grains and the width of martensite laths. In the aged state, higher Co content causes the precipitation phase to transform from an ellipsoidal Mo-rich phase to a needle-like Ni3(Mo, Ti) phase. These changes in the size, shape, and density of the precipitated phases result in a more pronounced effect of precipitation strengthening, leading to a significant increase in the material's strength.
NiTi//Al2O3 composites have many advantages such as large elasticity, superior hardness and wear resistance. But there is little information available about the novel adhesion strength, fracture ...mechanism and interfacial bonding of NiTi//Al2O3 composites at the atomic scale. Therefore, the work of adhesion (Wad), interfacial energy (γ) and electronic structure of NiTi(111)//α-Al2O3(0001) interfaces have been calculated using first-principles calculations. For the models with the same stacking site, O-terminated interfaces have larger Wad and smaller γ than Al-terminated interfaces. For the models with same termination, the stability of Ni(Ti)-Al interfaces decreases with the order of HCP > MT > OT, while the stability of Ni(Ti)-O interfaces decreases as MT > HCP > OT. The Ti-O-MT interface belongs to the most stable interfacial configuration with the smallest interface energy among all studied interfaces. Using Griffith's theory, it is predicted that the mechanical failure of NiTi//α-Al2O3 interfaces are inclined to initiate in the interior of NiTi bulk or at the interface rather than Al2O3 side in most cases. Furthermore, density of states and electron density difference analysis indicate that the dominant interfacial adhesion mechanism for the NiAl interfaces is the formation of mainly metallic TiAl and NiAl bonds, while the TiO interface exhibits mixed covalent/ionic character with higher interfacial binding strength.
The interface energies of Ni-Al2-HCP2 and Ti-Al2-HCP2 configurations at 298 K are increased with the increasing of the partial pressure of oxygen, indicating their thermodynamic stabilities are decreased in the oxygen rich condition. Meanwhile, the Ni-O-MT and Ti-O-MT interfaces are stabilized by increasing the partial pressure of oxygen. Display omitted
•NiTi//α-Al2O3 interfaces were studied to reveal their adhesion strength, fracture mechanism and interfacial bonding.•Ti-O-MT interface is the most stable interfacial configuration with the smallest interface energy of 2.07 J/m2.•The mechanical failure are inclined to initiate in the interior of NiTi bulk rather than the interface.
The ground state properties of W–C binary compounds (h-WC, c-WC, α-W
2C, β-W
2C, γ-W
2C, ɛ-W
2C) are studied in this paper by using first-principles calculations. Formation enthalpy and cohesive ...energy for each phase are calculated. The calculated elastic constants satisfy the Born–Huang's stability criterion, indicating all studied compounds are mechanically stable. All W–C compounds studied in this paper exhibit larger bulk modulus values than many other binary types of carbide such as Fe
3C, Cr
7C
3, Cr
3C, and TiC. Using a theoretical method based on the works of Šimůnek, the hardness of the crystal is estimated. The electronic structures of these compounds are calculated and discussed. Stoner's polarization theory for itinerant magnetism is applied to explain the observed paramagnetic behavior of the compounds. Moreover, the heat capacity is also calculated for each compound based on the knowledge of the elasticity and Debye temperature.
In this study, hot deformation behavior of in-situ nanosized TiB2/AZ91 composite is investigated by analyzing the constitutive equation, hot processing maps and microstructure evolutions. Hot ...compression tests are conducted in different temperatures and strain rates range of 523–673 K and 0.001–1 s−1 with a constant strain of 0.69. The results show that deformation temperatures and strain rates have a strong influence on the flow behavior of the composite, exhibiting typical work hardening, softening and steady stages. The constitutive equation is established through determining material constants, which can predict the flow stress precisely. In the meanwhile, the stress exponent (n) is calculated as 5.4, suggesting the hot deformation mechanism of TiB2/AZ91 composite is dominated by the dislocation climb. And the calculated apparent activation energy (Q) is 168.8 kJ/mol, which is higher than that of unreinforced AZ91 alloy due to the addition of nanosized TiB2 particles. Furthermore, the hot processing maps of TiB2/AZ91 composite are developed based on dynamic materials model, presenting three domains: one instability region in the range of 523–623 K & 0.01–1 s−1, and two safe regions in the range of 548–600 K & 0.001–0.005 s−1 and 648–673 K & 0.1–1.0 s−1 with the peak efficiency value of 0.36, respectively. By observing microstructures, full dynamic recrystallization (DRX) occurs in the safe regions, while the mechanism of instability region is dominated by mechanical twining and high density dislocation.
•The deformation mechanism of in-situ nanosized TiB2/AZ91 is clarified.•Constitutive equation of the composite is established.•Hot processing maps of TiB2/AZ91 composite at different strains are developed.•Two optimum processing windows of the composite are identified.
PDF
