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Metal sulfides have been universally studied as anode materials for lithium ion batteries (LIBs). Herein, we studied the lithiation storage behavior of a novel metal sulfide PbTiS3 (PTS), which is one of misfit layer compounds (MLCs) including intercalation-type TiS2 layer and conversion-alloying-type PbS layer. In-situ powder X-ray diffraction measurement reveals that the final lithiated product Li22Pb5 can be restored, indicating a reversible conversion-alloying mechanism in PTS. Theoretical calculation indicates the soft PbS interlayers of rock salt structure can hinder the distortion of TiS2 layers upon lithiation, resulting in a high structural integration of PTS anodes as well as a high concentration of intercalated Li ions. Moreover, with the assistance of the strong interfacial C–O–Pb/Ti interaction between PTS and graphene oxide (GO), PTS can be embedded in the conductive GO network which could stabilize PTS structure during long term cycling. Consequently, the fabricated LIBs anode delivers a relatively high reversible capacity (569 mA h g−1 at 2.0 A g−1 after 1000 cycles) and an outstanding high-rate capability. Besides, the assembled lithium ion full battery maintains a capacity retention of 70% after 100 cycles at 0.1 A g−1. This work provides insights into the design of MLCs as next-generation secondary batteries.

In this paper, we study the problem of robust Stackelberg game-based power control (RSG-PC) for spectral coexisting multistatic radar and massive multiple-input multiple-output (MIMO) communication systems. Recognizing that the path propagation gains cannot be assumed to be constant, the column-wise model is employed to describe the uncertainty of the parameters. The primary objective of the RSG-PC scheme is to minimize the worst-case radiated power of each radar with uncertain path gains for a specified signal-to-interference-plus-noise ratio (SINR) requirement for target detection, while the massive MIMO communication base station (MIMO-CBS) is protected from the interference of radar transmissions. The hierarchical competition between the massive MIMO-CBS and multiple radars are modeled as a robust single-leader multi-follower Stackelberg game. In the considered game model, the massive MIMO-CBS plays as the leader to decide the prices first through the maximization of its own utility. The radars act as the followers, who compete with each other in a non-cooperative Nash game according to the released interference prices from the massive MIMO-CBS subsequently. Based on the theoretical findings on the existence and uniqueness of the robust Nash equilibrium (RNE) in the formulated game, we present an iterative power control approach that guarantees the convergence to the RNE. Finally, the numerical simulations are provided to verify that our RSG-PC scheme can provide efficient power resource utilization, guarantee a predefined target detection performance, and also protect the quality of service (QoS) of massive MIMO-CBS with uncertainties in path propagation gains.

This article develops a collaborative radar node selection and transmitter resource allocation (CRNS-TRA) algorithm for target tracking applications in multiple radar architectures. The key mechanism of the CRNS-TRA strategy is to coordinate the radar node selection, transmit power, and dwell time of multiple radar architectures to enhance the target tracking accuracy under the constraints of several transmitter resource budgets. The analytical expression for the Bayesian Cramer-Rao lower bound (BCRLB) is derived and employed as the objective function to quantify the target tracking performance. It is shown that the CRNS-TRA problem is a mixed-integer, non-convex, and non-linear optimization problem, where the three involved parameters, that is, the radar node selection, transmit power and dwell time allocation, are all coupled in the objective function and the constraints. Subsequently, a fast and effective two-stage-based solution methodology is proposed for solving the resulting problem, which incorporates the interior point method and cyclic minimization framework. Extensive simulation results are provided to verify that the presented CRNS-TRA scheme is capable of effectively improving the target tracking performance with much lower operation time consumption when compared to other state-of-the-art resource allocation benchmarks.

With the objective of improving the construction efficiency and provide excellent performance of railway trackbed, the dry-mixed rubberized epoxy asphalt mixture (DREAM) was proposed to prepare the bi-block precast epoxy asphalt trackbed structure. Based on the coarse aggregate voids filling method combining the similitude method for gradation design of coarse aggregate and Superpave method for gradation design of fine aggregate, the gradation of mixture was determined. To analyze the feasibility of proposed asphalt trackbed material for railway structure, the fatigue test under 3 million repeated loadings and semi-circular bending test under the effect of aging and freeze–thaw cycles were conducted. After comprehensively understanding the test results, it was concluded that the DREAM with 11 wt% crumb rubber (CR) exhibited a better fatigue and fracture resistance compared with another type of DREAM with a lower content of CR, i.e., 9 wt%. Owing to a larger amount of CR, the DREAM with11 wt.% CR owned an outstanding ability of deformation recovery and ductile failure. Therefore, it was determined to be an effective asphalt trackbed material. Once the designed DREAM was selected, the corresponding bi-block precast epoxy asphalt trackbed finite element model was generated by using the ABAQUS software for the life-time deformation analysis through the time–temperature superposition principle. The numerical study and calculation of time–temperature conversion indicated that the train loading was mainly responsible for the permanent deformation. The value of permanent deformation caused by the train loadings was two times higher than that caused by static loading (e.g., steel and fastening).

With the rapid increase in the production of reclaimed asphalt pavement (RAP), asphalt pavement rejuvenation technology has attracted significant research attention. To improve the performance of recycled asphalt pavement mixtures, the rejuvenators are usually needed. A waste rubber/oil (WRO) rejuvenator was self-developed by mixing crumb rubber (CR) with waste cooking oil (WCO) at high temperature. However, the chemical dynamic interaction process between WCO and CR, and the effect of reaction time on the rejuvenation properties of the WRO rejuvenators still remained unclear. Therefore, in this study, the functional group and molecular weight of WRO rejuvenators with different reaction times and various WRO rejuvenated asphalts were studied by Fourier transform infrared spectroscopy and gel permeation chromatography, respectively. The rheological properties of various WRO rejuvenated asphalts were also tested using dynamic shear rheometer and bending beam rheometer. The result indicated the occurrence of complex depolymerization and recombination reactions of the polymers released from CR. WRO with higher rubber content exhibited higher polymer concentration. The WRO rejuvenator with a longer reaction time provided more viscous supplement and less elastic retention to the aged asphalt. As the reaction time of the WRO rejuvenator increased, the WRO rejuvenated asphalt showed less resistance to ageing, and the concentration of large molecules and sulfoxide function group in WRO rejuvenated asphalt was reduced. Based on the results, the recommended reaction time of WRO is 0.5 h.

Fatigue crack behavior of asphalt binder plays an important influence on the fatigue performance of asphalt pavements. To evaluate the fatigue crack density evolution within the steady growth stage of #70 unmodified asphalt binder and SBS modified asphalt binder, the crack initiation and propagation were characterized based on Griffith theory and modified Paris’ law, respectively. Aiming to calculate the horizontal length of crack initiation (a), the surface free energy of those two asphalt binders were calculated by contact angle measured with Wilhelmy plate test. Also, the stress sweep tests and time sweep tests were performed using Dynamic Shear Rheometer (DSR) to obtain the mechanical parameters of asphalt binders for calculation of fatigue crack density ( ϕ ) and dissipated pseudo strain energy (DPSE). They were fitted by modified Paris’ law, and coefficients n and A were determined. Results show that a for two asphalt binders increase with the increasing stress level and SBS modified asphalt binder shows a larger crack size in crack initiation, which means that SBS modified asphalt binder shows a better crack initiation resistance compared with unmodified asphalt binder. The ϕ and DPSE within the steady growth stage follow the linear relationship, indicating that the unit DPSE causes the equal amount of increase in ϕ . In addition, the A and n are independent on the stress levels. They are fundamental material properties and there is a linear relationship between the log(A) and n. SBS modified asphalt binder processes the better fatigue crack resistance because of the smaller value of n.

In this paper, a polymer modified bio-derived rejuvenator (PMBR) consisting of bio-oil, polymer modifier, and other additives (plasticizer, cross-linking agent) was investigated. The regeneration performance of PMBR on aged base and SBS modified bitumen was compared with that of commercial rejuvenator (CR) and bio-based rejuvenator (BR). The anti-cracking, anti-fatigue, anti-rutting and anti-moisture performance of aged base and SBS modified bitumen rejuvenated by CR, BR, as well as PMBR were evaluated via Dynamic Shear Rheometer (DSR) tests. The morphology, as well as the change of molecular functional groups of aged base and SBS modified bitumen rejuvenated by PMBR were studied by Fluorescence Microscopy (FM) and Fourier Transform Infrared Spectrum (FTIR). Glover-Rowe diagram results manifest that PMBR could restore the anti-cracking performance of aged bitumen to the level of virgin binder. Black diagram results show that PMBR rendered satisfactory elastic performance. Moreover, it is obtained from Linear Amplitude Sweep (LAS) results that PMBR performed better than conventional rejuvenators in reducing the damage rate and increasing the N f of aged bitumen. Additionally, Multiple Stress Creep Recovery (MSCR) results reveal that PMBR contained no severe side-effects on the high temperature performance, and rendered better elastic recovery to aged bitumen. The Shear Test results show that PMBR rejuvenated bitumen contained better anti-moisture ability as well as better network structure strength among all rejuvenated bitumen. Finally, the reaction between PMBR and aged SBS modified bitumen and the restoration of network structure was revealed via analyzing the morphology studied by the FM test, and characterizing the the C─S stretching vibrations and ─CH═CH─ vibrations in polybutadiene block obtained from the FTIR test. It is verified that the polymer and crosslinking agent replenished by PMBR reacted with the originally destroyed SBS segment in aged SBS modified bitumen. Then the network structure was restored, which could explain the rheological properties of aged bitumen rejuvenated by PMBR.

Misfit layer SnTiS3 (STS) crystal as a bulk van der Waals (vdW) heterostructure SnS/TiS2 is developed as a superior anode material for lithium-ion batteries (LIBs). STS can combine the advantages of metallic character of TiS2 layers and high lithium-storage of SnS layers. Moreover, graphene oxide (GO) is adopted to support STS via a hand-grinding route. A strong binding between STS and GO is conducive to decreasing the crystalline domain size of STS. Besides, the in-situ electrochemical reduction of GO nanosheets during the first cycling could offer a conductive network for both ions and electrons. Consequently, the electrochemical performance of STS/GO is superior than that of pristine STS and STS/rGO (rGO = reduced GO), and outstanding among the latest reports of SnS- or TiS2-based on LIBs anodes. Specifically, STS/GO anode delivers a capacity of 614 mA h g−1 at 2.0 A g−1 after 1000 cycles, as well as a high rate capability due to the dominated surface-capacitive contribution. Furthermore, the combination of in-situ and ex-situ powder X-ray diffraction patterns unequivocally reveals a conversion-alloy mechanism in STS anode upon lithiation/delithiation.

While as a jointless cementitious asphalt material, semi-flexible pavement material (SFP) behaves well in rutting resistance, cracking has been a major barrier in its application promotion. Although many material modifications have been proved effective to improve SFP’s performance to some degree, it is still unclear what the crack mechanism is and whether it is similar in asphalt concrete until now. Thus, splitting test was conducted on SFP at three different temperatures (−10 °C, 10 °C and 25 °C) to investigate SFP’s damage process. Acoustic Emission (AE) technique was employed at the same time to collect signals from various of damage sources. An unsupervised method, k-means, was used to classify AE data. The X-ray scanning images of the samples after fracture were observed to assist in cluster identification, together with the images of the fracture cross sections. Three damage mechanism clusters were identified as skeletal aggregate moving friction, together with cement cracking, asphalt cohesive damage and debonding. The result reveals that SFP cracks more easily at 25 °C. There is a temperature effect in the damage process of SFP: the damage mode shifts from main macro-crack to distributed meso-cracks, as well as from interface debonding, aggregate cracking to asphalt/cement damage. Besides, the absolute energy development of each cluster indicates that damage in cement caused by uncoordinated deformation contributes much to capability loss in SFP at 25 °C.

Fatigue crack is one of the most common distresses in asphalt pavement. In this study, the fatigue crack behaviors of asphalt binders were evaluated under repeated cyclic controlled-stress loadings. Fatigue crack density, defined by the initial sample radius and effective radius of the undamaged part during fatigue testing, was used as an indicator. Also, an effective radius function was developed using the torque equilibrium principle and dissipated strain energy (DSE) equilibrium principle. The data revealed that fatigue crack density of asphalt binder manifested three changing tendencies, in which the secant method was employed to partition their profiles based on concavity and convexity characteristics. Specimens made of #50, #70 unmodified asphalt, SBS modified asphalt, and #50 asphalt mastic, respectively, were tested by time sweep tests on a Dynamic Shear Rheometer (DSR) at different stress levels and rest time. The variations in fatigue crack density at the three stages, as well as the changes in fatigue crack density growth rate in the second stage, were all analyzed. The asphalt binder showed fatigue crack density profiles composed of three stages: crack initiation, steady growth, and unstable growth. Stage II had the smallest increase in fatigue crack density among the three stages but underwent more than 50% load cycles throughout the whole fatigue process. Hence, fatigue crack density growth rate (RD) could be used to evaluate the fatigue resistance of asphalt binders. A positive power-law relationship between RD and stress level was recorded since higher stress levels meant more serious damage. By contrast, RD displayed a negative power-law relationship with resting time, revealing that the rest time, that is, self-healing, effectively postponed the fatigue crack propagation rate.