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A tracking controller for unmanned aerial vehicles (UAVs) is developed to track moving targets in the presence of occlusion. The controller can track moving targets based on a bounding box of the target detected by a deep neural network using the you-only-look-once (YOLO) method. The features generated from the YOLO approach relaxes the assumption of continuous availability of the feature points for applications, which facilitates estimation using an unscented Kalman filter (UKF) and the design of image-based tracking controller in this work. The challenge is that when occlusion is present, the bounding box of the moving target becomes unobtainable and makes the estimation diverge. To solve this, a motion model derived by quadratic programming is employed as a process model in the UKF, wherein the estimated velocity is implemented as a feedforward term in the developed tracking controller in order to enhance the tracking performance. Since no motion constraint is assumed for the target, the developed controller can be applied to track various moving targets. Simulations are used to demonstrate the performance of the developed estimator and controller in the presence of occlusion. Experiments are also conducted to verify the efficacy of the developed estimator and controller.

A decentralized event-triggered approach is developed for leader–follower systems with time-invariant and time-varying network topologies in the absence of full-state feedback. Continuous interagent communication is eliminated by communicating information only during events. At the event times, an observer communicates with the neighboring agents to obtain update information. During the interevent intervals, an open-loop estimate is used as a substitute for local feedback. The advantages of our novel approach are that: 1) the amount of communication required can be reduced and determining the event times requires no interagent communication, with the event-triggered condition designed using stability analysis so that bounded consensus is guaranteed; 2) bounded state consensus can be achieved without receiving full-state information from the followers; and 3) the switching sequence of the time-varying network topologies can be arbitrary, since a switching controller is developed based on the common-Lyapunov-function approach to ensure state consensus. Intermittent feedback is present and the dynamics of the time-varying network topologies are discrete, which together prove that Zeno behavior never occurs. The stability of the closed loop is analyzed to guarantee bounded convergence for the designed control methodologies. The results of simulations are presented that demonstrate the efficacy of our novel controllers.

An efficient Pd-catalyzed double annulation reaction of 1-(2,6-dibromophenyl)-1H-pyrroles with arynes is developed to synthesize π-extended dibenzo[d,k]ullazines in good to excellent yields. For the first time, the parent dibenzo[d,k]ullazine core is obtained and characterized.

The development of multimetallic Pt-based nanostructures as high-performance cathodic electrocatalysts to be used in water-splitting devices for hydrogen generation is the focus of increasing attention. In this study, a family of hierarchical architectures constructed from dendritic quaternary PtFeRuRh, ternary PtFeRh or PtFeRu and binary PtFe nanoalloys are achieved via a general liquid-phase strategy for hydrogen evolution in alkaline electrolyte. Among them, the PtFeRuRh nanoalloys exhibit the lowest overpotential (20.0 mV at 10 mA cm−2) and Tafel slope (21.1 mV dec−1). At a potential of −0.07 V, the mass activity of the PtFeRuRh nanoalloy is 7.04 A mgPt−1, it is 6.97 times that of commercial Pt/C. The dendritic PtFeRuRh nanoalloys exhibit a negligible decrease in activity after 20 h of continuous testing at 10 mA cm−2/100 mA cm−2 and 3000 cyclic voltammetry cycles. In a practical application, the cell voltage of a PtFeRhRu (−) || IrO2 (+) couple is 1.568 V at 10 mA cm−2 with almost 100% faradaic efficiency. The turnover frequency of the PtFeRhRu electrocatalyst at 70 mV was 78.5 s−1, which is 11.71 times as large as that of commercial Pt/C (6.7 s−1).

In this study, the plasma oxidation effect in tin-oxide (SnOx) thin film was investigated. And on this basis, we fabricated n-type thin-film transistors (TFTs) using the SnOx thin film with the plasma oxidation by experiments. By adjusting the processing time of the oxygen plasma treatment (OPT), the optimized SnOx TFT device exhibited an extremely high field-effect mobility of 87.6 cm2 V−1 s−1, a desirable on-to-off current ratio of 1.9 × 104 and a threshold voltage of − 0.9 V. Furthermore, we investigated the origin of the performance enhancements in the n-type SnOx TFTs with the optimized OPT by introducing the density of states (DOS) modeling in TCAD simulation. The numerical simulation indicated that the attributes of donor-like Gaussian defect states (oxygen vacancies) were modified in overall DOS due to the plasma oxidation effect. These present results show that the SnOx TFT treated by oxygen plasma has great promise in the future high-performance flat panel display industries.

In this study, we investigated the stress and doping effects of ferroelectric hafnium zirconium oxide (HfZrO) based on material analysis and electrical characteristics. The experimental results revealed that the ferroelectric crystalline phase is effectively transferred by mechanical stress of tantalum nitride (TaN) electrodes, and the origin of stress is mainly the thermal residual stress formed near the TaN and HfZrO interface. The ferroelectric polarization characteristics of HfZrO can be further modified by additional Al doping, which not only improves the leakage current of HfZrO due to the large bandgap of Al2O3 but also simultaneously stabilizes the ferroelectric domain switching under a large coercive field.

A leader–follower system is developed to cooperatively swing a payload up to a desired angle without interagent communication. The main advantages of this system are that no force sensor is require...

Background The interfacial performance of protein and polysaccharide plays a vital role in the improvement of food quality. As an innovative technology in food processing, cold plasma has attracted much attention from researchers and has become an attractive tool for nonthermal food processing due to the abundant reactive species generated at low temperatures. In particular, cold plasma shows great potential in food component modification. However, some of the specific physical-chemical reactions between reactive species in plasma, and protein and polysaccharide still remain obscure, limiting the development of accurate modification. Scope and approach This review provides an overview of the effects that plasma makes on the interfacial performance of protein and polysaccharide in the emulsion. Aspects discussed include types of active species in cold plasma, detailed interaction between reactive species, and protein and polysaccharide, and changes of interfacial properties. In addition, the current review presents a summary of the modification of protein and polysaccharide resulting from cold plasma application. Key findings and conclusions The reactive species produced by cold plasma improve the interfacial performance of protein and polysaccharide by changing their residue composition and stereostructure. In the process of modification, hydrophobic groups hidden in protein are exposed and hydrophilic groups are grafted onto the polysaccharide skeleton. Meanwhile, the structural looseness is changed due to the breakage and the formation of bonds. Although successful applications of cold plasma for protein and polysaccharide modification have been demonstrated, it is not enough to characterize the changes at the macro level, and more in-depth studies should be conducted in the future. To improve the interfacial performance of protein and polysaccharide, the mechanism of plasma regulatable modification should be explored, and the accuracy of modification should be enhanced.

The water absorption and desorption processes of different types of lightweight aggregates were studied. Subsequently, the influences of pre-wetting lightweight aggregates on compressive strength, microhardness, phase composition, hydration parameters and micromorphology of the cement pastes were investigated. The results showed that the water absorption and desorption capacities of the lightweight aggregates increased with the decrease of the densification degree. With the addition of pre-wetting lightweight aggregates, the compressive strength of the cement pastes would increase. Moreover, the enhancement effect was more obviously with the desorption capacity of pre-wetting lightweight aggregates increasing. Especially, sample S1 with pre-wetting red-mud ceramisites had the highest compressive strength, of which increased to 49.4 MPa after 28 d curing age. The reason is that mainly because the addition of pre-wetting lightweight aggregates can promote the generation of C–S–H gels in the interfacial zone, and the hydration degree of the interfacial zone increases with the water desorption of pre-wetting lightweight aggregates increasing. It is contributed to optimize the microstructure to enhance microhardness of the interfacial zone, resulting in the compressive strength of the cement-based materials improving. Therefore, the pre-wetting lightweight aggregates with high porosity and strength are the potential internal curing agents for high-strength lightweight concretes.

In this work, we revealed that Sb2Se3 has one second-order isostructural phase transitions before it eventually transformed into a site-disordered alloy during compression. Then, a rare amorphizati...

In this work, we demonstrated a HfO2-based ferroelectric field-effect transistor (FeFET) in series with a HfAlO ferroelectric capacitor for memory application and further investigated the impact of the ferroelectric capacitor with different thicknesses and areas. It was revealed that the memory window of the FeFET has a significant correlation with the ferroelectric capacitor from the transfer curves of the transistor after the series connection. By decreasing the thickness and area of the ferroelectric capacitor, the memory window of the FeFET was improved, which could be verified through the TCAD simulation tool and capacitance matching model. With the series-connected ferroelectric capacitor, in addition to optimizing the characteristics of ferroelectric memory, we can effectively avoid the interface-caused undesirable effects in conventional ferroelectric memory during film stacking. These results provide a solution for future low-power embedded memory application.

In this paper, we investigated the performance of an n-type tin-oxide (SnOx) thin film transistor (TFT) by experiments and simulation. The fabricated SnOx TFT device by oxygen plasma treatment on the channel exhibited n-type conduction with an on/off current ratio of 4.4×104, a high field-effect mobility of 18.5 cm2/V.s and a threshold swing of 405 mV/decade, which could be attributed to the excess reacted oxygen incorporated to the channel to form the oxygen-rich n-type SnOx. Furthermore, a TCAD simulation based on the n-type SnOx TFT device was performed by fitting the experimental data to investigate the effect of the channel traps on the device performance, indicating that performance enhancements were further achieved by suppressing the density of channel traps. In addition, the n-type SnOx TFT device exhibited high stability upon illumination with visible light. The results show that the n-type SnOx TFT device by channel plasma processing has considerable potential for next-generation high-performance display application.

Transparent electronics has attracted much attention and been widely studied for next-generation high-performance flat-panel display application in the past few years, because of its excellent electrical properties. In display application, thin film transistors (TFTs) play an important role as the basic units by controlling the pixels. Among them, oxide-based TFTs have become promising candidates and gradually replaced the conventional amorphous and polycrystalline silicon TFTs, due to high mobility, good transparency, excellent uniformity and low processing temperature. Even though n-type oxide TFTs have shown high device performance and been used in commercial display application, p-type oxide TFTs with the equal performance have been rarely reported. Hence, in this paper, recent progress and challenges in p-type oxide-based TFTs are reviewed. After a short introduction, the TFT device structure and operation are presented. Then, recent developments in p-type oxide TFTs are discussed in detail, with the emphasis on the potential p-type oxide candidates as copper oxide, tin oxide and nickel oxide. Moreover, miscellaneous applications of p-type oxide TFTs are also presented. Despite this, the performance of p-type oxide TFTs still lags behind, as compared with that of n-type counterparts. Thus, the current issues and challenges of p-type oxide TFTs are briefly discussed.

Optimal device integrity was achieved in Ni/SiGeOx/TiOy/TaN resistive memory by using a forming-free switch with a low switching power of 790 μW, stable endurance of 104 cycles, optimal retention time of 105 s, resistance window of at least 1150×, and tight current distributions at 85 °C. These characteristics are attributed to the low current switching obtained using SiGeOx with a high oxygen vacancy density and highly defective TiOy grain boundaries.

Deep Reinforcement learning agent has outperformed human players in many games, such as the Atari 2600 games. In more complicated games, previous related works proposed a curiosity-driven exploration for learning. Nevertheless, it generally requires substantial computational resources to train the agent. We attempt to design a method to assist with our agent to explore the environment. By utilizing prior learned experience more effectively, we develop a new memory replay mechanism, which consists of two modules: Trajectory Replay Module to record the agent moving trajectory information with much less space, and the Trajectory Optimization Module to formulate the state information as a reward. We evaluate our approach with two popular side-scrolling video games: Super Mario Bros and Sonic the Hedgehog. The experiment results show that our method can help the agent explore the environment efficiently, pass through various tough scenarios and successfully reach the goal in most of the testing game levels with merely four workers and of ordinary CPU computational resources for training. The demo videos are at Super Mario Bros and Sonic the Hedgehog.

The viscoplasticity and compressive strength of cement with high erosion performance were studied. The influences of curing temperature and content of ground granulated blast furnace slag (GGBFS) on these performances of the medium heat cement (including high iron and low calcium phase) were also investigated. The results indicate that the medium heat cement with high iron phase can maintain better fluidity and low temperature sensitivity than that of ordinary Portland cement at high temperature. GGBFS can play an important role in improving the fluidity and stability of the slurry, and avoid the cement setting and hardening prematurely at high temperatures. The microstructure analysis shows that a large amount of CH with layer shape appear in the slurry. The amount of this gel layer in the slurry increased as the curing temperature elevated. The layer can make the cement stone structure more denser, so that the compressive strength of samples are enhanced in the later stage. When the medium heat cement contains 40% GGBFS, the system has the best flow performance and stability under high temperature environment, and can be applied to mass concrete with excessive internal temperature.

In this study, safety margin explicit equation has been established using random variables (i.e., the engineering conditions, structure parameters, structural strength, and external load), and the genetic algorithm (GA)–based structural reliability optimization design has been addressed subsequently. Though the conventional adaptive GA can change automatically with fitness, it is still not unsatisfactory in sufficiently improving the algorithm convergence speed, especially for complex structures. This article presents an improved adaptive technology termed as the distant relative genetic algorithm (DRGA), in which the distant relative pointer and immunity operators can effectively improve the search performance of the GA. In early evolution, by means of cross controlling and avoiding pairing between individuals with the same genes, the methodology prevents the isogenic individuals expanding locally. Besides, the revised algorithm is able to jump out of the local optimal solution, thus ensuring the realization of a fast global convergence. An example based on wing box structure optimization has been demonstrated using the improved method, and the calculation results show that this strategy makes the GA more effective in dealing with the constraint optimization issues.

Most UAVs rely on GPS for localization in an outdoor environment. However, in GPS-denied environment, other sources of localization are required for UAVs to conduct feedback control and navigation. LiDAR has been used for indoor localization, but the sampling rate is usually too low for feedback control of UAVs. To compensate this drawback, IMU sensors are usually fused to generate high-frequency odometry, with only few extra computation resources. To achieve this goal, a real-time LiDAR inertial odometer system (RTLIO) is developed in this work to generate high-precision and high-frequency odometry for the feedback control of UAVs in an indoor environment, and this is achieved by solving cost functions that consist of the LiDAR and IMU residuals. Compared to the traditional LIO approach, the initialization process of the developed RTLIO can be achieved, even when the device is stationary. To further reduce the accumulated pose errors, loop closure and pose-graph optimization are also developed in RTLIO. To demonstrate the efficacy of the developed RTLIO, experiments with long-range trajectory are conducted, and the results indicate that the RTLIO can outperform LIO with a smaller drift. Experiments with odometry benchmark dataset (i.e., KITTI) are also conducted to compare the performance with other methods, and the results show that the RTLIO can outperform ALOAM and LOAM in terms of exhibiting a smaller time delay and greater position accuracy.

Coastal bridges are continually attacked by chloride ions during their lifetime, making the structures vulnerable. Piers, which are the main components of bridge structures to resist later...

In this paper, the effect of channel annealing and oxygen flow rate in P-type tin-monoxide (SnO) thin film transistor (TFT) was investigated to reach the process compatibility with n-type oxide-based TFT. The optimized P-type SnO TFT with a small threshold voltage of -0.1 V, a high field-effect mobility of 4 cm² V-1 s-1 and an on/off current ratio of >10² was proposed. From the experimental results, the 150 °C channel annealing revealed a metallic behavior but a semiconductor-like property at a higher 200 °C that was favorable for transistor rectification. Besides, the higher oxygen flow rate was also helpful for improving device mobility and driving current, but shows a slight increase in off-state leakage, which is unavoidable due to the increase of grain in SnO channel.

In this work, we successfully demonstrated the 9.6-nm-thick HfAlOx ferroelectric memory using light aluminium doping of 6.5% to form ferroelectric orthorhombic phase. Compared to ferroelectric HfZrOx film with zirconium diffusion issue, the HfAlOx film showed excellent thermal stability under high temperature annealing. Besides, the ferroelectric HfAlOx also exhibited robust polarization characteristics under endurance cycling test. A >106 stressed cycles with 4 MV/cm can be measured and a long endurance was sustained over 5 × 107 cycles under 3.6 MV/cm. Therefore, the HfAlOx film showed the great promise for integrating in high performance ferroelectric memory with thermal budget concerns.

Metal-organic frameworks (MOFs) derived porous carbons are promising electrode materials in electrochemical energy conversion and storage systems. However, the typical synthetic route of MOFs involving high temperature, organic solvent, massive energy consuming, and laboratory-scale production, hinders the realistic applications of MOFs serving as sacrificial templates for porous carbon. Herein, we demonstrate that highly crystalline MIL-100 (Fe) nanoparticles (MIL: Materials of Institute Lavoisier) can be synthesized in large scale with low cost under mild and green conditions. High-temperature pyrolysis of MIL-100(Fe) under argon atmosphere results in hollow carbon polyhedra (HCPs) featuring high degree of graphitization and hierarchical pore structures. The obtained HCPs are excellent electrode materials for electric double-layer capacitors (EDLCs), and show a specific capacitance of 214 F g−1 at current density 50 mA g−1. Moreover, the HCP-based supercapacitors can endure more than 5000 cycles without significant degradation of capacitance. The unique structure of HCPs, including hollow polyhedral shape, hierarchical micro/mesopore structures, and ultrathin layer of highly graphitized carbon shells, endows the superior performance of HCPs based EDLCs with specific capacitance and high rate capability.

FeCoCrNiMnTi0.1C0.1 (TiC10 alloy) high-entropy alloy (HEA) was successfully prepared by mechanical alloying (MA) and vacuum hot-pressing sintering (VHPS) at different temperatures (850, 900, 950 and 1000 °C). During the MA process, the constituent elements were gradually alloyed and formed FCC solid solutions. The microstructure of bulk TiC10 alloy is mainly composed of FCC phase as the matrix phase and a small quantity of M23C6, M7C3 and TiMnO3 phases. The TiC10 alloy has relatively good comprehensive mechanical properties when sintered at 900 °C. The yield strength and hardness of the alloy reached 1652 MPa and 461 HV, respectively. In this study, a close relationship between microstructure and mechanical properties was discussed. Grain boundary strengthening is the dominant strengthening mechanism.

Organometal halide perovskites offer tremendous potential in developing optoelectronic and photovoltaic devices because of their spectacular band gap properties. Pressure has been demonstrated to b...

This paper presents a methodology to perform seismic fragility analysis of deteriorating reinforced concrete (RC) bridge columns induced by corrosion based on time-variant capacity estimates. The typically simplified uniform reduction model of cross-section of a corroded reinforcing steel bar is assumed, and the strain penetration and slippage of reinforcements anchored to the foundation are considered in the performance assessment of corroded bridge columns. To be conveniently used in engineering practice, the drift ratio is taken as the capacity index to quantify various damage states, and the plastic hinge model is adopted and verified to calculate the tip displacement of corroded columns due to its simple form and wide use in elastic–plastic analysis. Seismic fragility curves are then developed with reference to both the pristine (or original) construction state and current deteriorated state to illustrate the differences of potential damage probabilities calculated by time-invariant and time-variant capacity indexes. Further, significance test is performed. The results highlight that some of the empirical plastic hinge length models can also be used to predict the ultimate displacements of corroded columns by introducing the corroded constitutive models of materials; the seismic performance of a deteriorating RC bridge column will be significantly underestimated by using pristine capacity index as the measurement criterion. As a matter of fact, in engineering practice, one of the main concerned issues should be the current structural failure probability when evaluating the performance of a deteriorated RC structure. Hence, it is suggested that the time-variant capacity index should be adopted to estimate the seismic performance of a deteriorating RC structure during its life cycle.

To improve the strength and hardness, Al-containing FeCoCrNiMn high-entropy alloys (HEAs) were fabricated by mechanical alloying (MA) and hot-pressed sintering. The effects of Al concentration on the microstructure and mechanical properties of the alloys were examined. It was found that the Al-containing alloys consisted of the matrix fcc or fcc + bcc duplex solid solution phases and a small quantity of M7C3 + M23C6 (where M = Cr, Mn, Fe) carbides and Al2O3 phases. A high Al concentration induced bcc precipitates in the alloys, and with the increase of Al concentration, the crystalline structure of the matrix solid solution phase changed from fcc to bcc. The addition of Al obviously strengthened the alloys, especially the alloys that contained fcc + bcc duplex solid solution phases. For example, the yield strength, compressive strength and hardness of alloy FeCoCrNiMnAl0.7 reached as high as 2230 MPa, 2552 MPa and 622 HV, respectively. The high strength/hardness was attributed mainly to the finer grains and the bcc precipitation.

This paper proposes a new class of filtering power dividers integrated with phase shifter and impedance transformer simultaneously for the first time. In contrast to the conventional approaches, the proposed filtering power dividers consist of two asymmetrical generalized bandpass networks, that can achieve arbitrary constant phase difference and good isolation at two output ports. On the one hand, the magnitude and phase properties of two generalized $n^{\mathrm {th}}$ -order bandpass networks are systematically studied and fully considered to realize the prescribed power division, filtering function, constant phase difference, and impedance transformation in the co-design. On the other hand, in order to obtain good isolation, the resonator’s type and impedance of these two asymmetrical networks are carefully considered and closed-form formula of isolation resistor is also deduced. Theoretical results show that the proposed topology can achieve perfect isolation over entire passband for the arbitrary phase difference. Meanwhile, the synthesis procedures are presented for a quick design process. Finally, two porotypes (90° power divider and 120° power divider) with specified different operation bandwidth (15% and 25%), filter order (3rd and 6th), and terminated port impedances ( $50\Omega $ and $100\Omega$ ) are synthesized, fabricated, and tested to verify the proposed design method and predicted frequency responses. It firstly integrates the power divider, filter, phase shifter, and impedance transformer into single component and has several additional advantages, such as low cost, simple geometry, small phase deviation and amplitude imbalance, and easiness for design and fabrication.

Image sensors have widespread use in many robotics applications and, in particular, in target tracking. While existing methods assume continuous image feedback, the novelty of this brief stems from the development of dwell time conditions to guarantee convergence of state estimates to an ultimate bound for a class of image-based observers in the presence of intermittent measurements. A Lyapunov analysis for the switched system is performed to develop convergence conditions based on the minimum amount of time the object must be visible and on the maximum amount of time the object may remain outside the camera view. Experimental results are included to verify the theoretical results and elucidate real-world performance.

Analysis and characterization of micro/nano-sized pore structure are critical issues in shale geology and engineering. Scanning electron microscopy (SEM) imaging is one of the most widespread methods for the analysis of the micro/nano-sized pores in shale, but precise identification of the ultrafine pore structure in shale is still a big challenge because shale is so complex that some components may have overlap with pores based on the simple discrimination of gray scale under SEM microscopy. Here, Fe3O4/Au nanocomposite with magnetic properties is synthesized, characterized, and introduced as a novel pore-marker to improve SEM identification and quantitation of micro/nano-sized pores in shale. Due to the superparamagnetic property, the nanomarker is conveniently controlled by an external magnetic field to fill into pores and offers a sharp contrast imaging between matrix of shale (various gray) and pores (bright), which makes the identification of micro/nano-sized pores in shale much more straightforward...

Electronic states of a correlated material can be effectively modified by structural variations delivered from a single-crystal substrate. In this letter, we show that the CrN films grown on MgO (001) substrates have a (001) orientation, whereas the CrN films on {\alpha}-Al2O3 (0001) substrates are oriented along (111) direction parallel to the surface normal. Transport properties of CrN films are remarkably different depending on crystallographic orientations. The critical thickness for the metal-insulator transition (MIT) in CrN 111 films is significantly larger than that of CrN 001 films. In contrast to CrN 001 films without apparent defects, scanning transmission electron microscopy results reveal that CrN 111 films exhibit strain-induced structural defects, e. g. the periodic horizontal twinning domains, resulting in an increased electron scattering facilitating an insulating state. Understanding the key parameters that determine the electronic properties of ultrathin conductive layers is highly desirable for future technological applications., Comment: 19 pages, 4 figures

Invasive plants pose a significant threat to natural ecosystems because of their high adaptability, rapid propagation and spreading ability in the environment. In this study, a typical aquatic invasive plant, Pistia stratiotes, was chosen as a novel feedstock for the preparation of nitrogen-doped biochars (NBs) for the first time, and the NBs were used as efficient sorbents to remove phthalate esters (PAEs) from aqueous solution. Characterization results showed that NBs possess great pore structure (up to 126.72 m2 g−1), high nitrogen (2.02%–2.66%) and ash (24.7%–34.1%) content, abundant surface functional groups, hydrophobicity and a graphene structure. Batch sorption experiments were performed to investigate the sorption performance, processes and mechanisms. The capacities for PAEs sorption onto NBs were high, especially with NBs pyrolyzed at 700 °C, ranging up to 161.7 mg g−1 for diethyl phthalate and 85.4 mg g−1 for dibutyl phthalate; these levels were better than many reported for other sorbents. With kinetic and isotherm results, Pseudo-second order and Freundlich models fit the sorption data well, and chemical interactions involving hydrogen bonding, Lewis acid-base interaction, functional group interaction, cation-π interaction and π-π stacking interaction were identified as possible rate-limited steps. Moreover, Intra-particle diffusion and Dubinin-Radushkevich models indicated that multiple pore filling and partitioning dominated the process of PAEs sorption onto NBs. This study opens the door for new methods of pollution control with waste treatment, since invasive plant biomass resources were converted into advanced biochars for efficient environmental remediation.

The anchorage slip of longitudinal reinforcement in the foundation (also called strain penetration effect) may affect the cyclic behavior of RC columns by inducing fixed-end rotations. This strain penetration effect could become more significant under reinforcement corrosion, which frequently occurs in RC structures exposed to the attack of aggressive agents such as chlorides. It is hence important to take corrosion effects into account in the modeling of strain penetration phenomena. This paper presents a modification of an existing stress versus slip hysteretic model for reinforcing steels to incorporate corrosion effects. Results of both pull-out tests of deformed steel bars and quasi-static tests of corroded RC columns are adopted for validation. Moreover, a parametric investigation is carried out to demonstrate the impact of structural parameters and corrosion levels on the cyclic response of corroded RC columns considering the strain penetration effect. The results highlight that the modified hysteretic model can efficiently simulate the anchorage slip. In addition, it is found that the strain penetration effect tends to be more significant for the RC columns with higher corrosion level, smaller aspect ratio, larger longitudinal reinforcement ratio, or lower axial load ratio.

This paper proposed a design of axial-flux integrated starter generator (ISG) drive system in the application of hybrid electric vehicles (HEVs). The system contains an axial-flux permanent magnet synchronous motor (AFPMSM) and its drive, which are compact designed. A series water-cooling channel is designed from the drive to ISG. It reduces cables and space of cooling system, which also benefit to high torque density. A simple and optimized flux-weakening and DC current estimation method based on flux-oriented control (FOC) algorithm are implemented to achieve high-performance control. Considering the sensitivity of the device to the power-up sequence and safety of users, an active discharge algorithm is proposed to release the charge. The drive system is tested on the test bench by the host computer via CAN bus and has achieved good dynamic response characteristics and high efficiency.

In this paper, we propose a novel algorithm that estimates the pose of the robot end effector using depth vision. The input to our system is the segmented robot hand point cloud from a depth sensor. Then a neural network takes a point cloud as input and outputs the position and orientation of the robot end effector in the camera frame. The estimated pose can serve as the input of the controller of the robot to reach a specific pose in the camera frame. The training process of the neural network takes the simulated rendered point cloud generated from different poses of the robot hand mesh. At test time, one estimation of a single robot hand pose is reduced to 10ms on gpu and 14ms on cpu, which makes it suitable for close loop robot control system that requires to estimate hand pose in an online fashion. We design a robot hand pose estimation experiment to validate the effectiveness of our algorithm working in the real situation. The platform we used includes a Kinova Jaco 2 robot arm and a Kinect v2 depth sensor. We describe all the processes that use vision to improve the accuracy of pose estimation of the robot end-effector. We demonstrate the possibility of using point cloud to directly estimate the robot’s end-effector pose and incorporate the estimated pose into the controller design of the robot arm.

Learning-based grasp pose detection algorithms have boosted the performance of robot grasping, but they usually need manually fine-tuning steps to find the balance between detection accuracy and efficient. In this paper, we discard these intermediate procedures, like sampling grasps and generating grasp proposals, and propose an end-to-end grasp pose detection model. Our model uses the RGB image as the input and predicts the single grasp pose in each small grid of the image. Furthermore, the best grasps are found by non-maximum suppression (NMS) strategy. The clustering and ranking procedures are left for NMS while the network only generates dense grasp predictions, which keeps the network simple and efficient. To achieve dense predictions, the predicted grasps of our detection model are represented by the 6 channels images with each pixel location representing a rated grasp. To the best of our knowledge, our model is the first neural network that attaches a grasp pose in pixel level. The model achieves 96.5% accuracy which costs 14ms for prediction of a 480×360 resolution RGB image in Cornell Grasp Dataset, and 90.4% robot grasping success rate for unknown objects with a parallel plate gripper in the real environment.

In this paper, the dynamic compressive mechanical properties of entangled metallic wire material (EMWM) under low-velocity impact were investigated and the constitutive model for EMWM under low-velocity impact was established. The research in this paper is based on a series of drop-hammer tests. The results show that the energy absorption rate of EMWM is in the range from 50% to 85%. Moreover, the EMWM with a higher relative density would not plastically deform macroscopically and has excellent characteristics of repetitive energy absorption. With the increase in relative density, the maximum deformation of EMWM decreases gradually, and the impact force of EMWM increases gradually. With the increase in impact-velocity, the phenomenon of stiffness softening before reaching the maximum deformation of EMWM becomes more significant. A constitutive model for EMWM based on the Sherwood&ndash, Frost model was established to predict the dynamic compressive mechanical properties of EMWM. The accuracy of the model was verified by comparing the calculated results with the experimental data of the EMWM with different relative densities under different impact-velocities. The comparison results show that the established model can properly predict the dynamic compressive mechanical characteristics of EMWM under low-velocity impact loading.

New refractory hard materials with a favorable band gap are in high demand for the next-generation semiconductors capable of withstanding high temperature and other hostile environments. Boron phosphide (BP) is such an attractive candidate with exceptional properties; however, it has mainly been studied theoretically because of the difficulty in sample preparation. In this work, we report successful synthesis of large millimeter-sized single-crystal BP. The final product has a zinc-blende structure with a unique electronic structure and is optically transparent with a moderate band gap of \ensuremath{\sim}2.1 eV. Our experiments, in conjunction with ab initio simulations, reveal that the compound exhibits extraordinary strain stiffening and unusually high load-invariant hardness of \ensuremath{\sim}38 (3) GPa, which is close to the 40-GPa threshold for superhard materials, making BP the hardest among all known semiconductors. Based on the first-principles calculations, the fracture mechanisms in BP under tensile and shear deformations can be attributed to the formation of a metastable hexagonal phase. Further spectroscopic measurements indicate that an unusual electronic transition occurs at high pressures of \ensuremath{\sim}13 GPa, resulting in an asymptotically enhanced covalent bonding state. The pressure dependence of multiphonon processes is also determined by Raman measurement. In addition, our studies suggest a phonon-assisted photoluminescence process and evidence for the photon-pumped \'etalon effect at 707 nm.

Strain engineering provides the ability to control the ground states and associated phase transition in the epitaxial films. However, the systematic study of intrinsic characters and their strain dependency in transition-metal nitrides remains challenging due to the difficulty in fabricating the stoichiometric and high-quality films. Here we report the observation of electronic state transition in highly crystalline antiferromagnetic CrN films with strain and reduced dimensionality. Shrinking the film thickness to a critical value of ~ 30 unit cells, a profound conductivity reduction accompanied by unexpected volume expansion is observed in CrN films. The electrical conductivity is observed surprisingly when the CrN layer as thin as single unit cell thick, which is far below the critical thickness of most metallic films. We found that the metallicity of an ultrathin CrN film recovers from an insulating behavior upon the removal of as-grown strain by fabrication of first-ever freestanding nitride films. Both first-principles calculations and linear dichroism measurements reveal that the strain-mediated orbital splitting effectively customizes the relatively small bandgap at the Fermi level, leading to exotic phase transition in CrN. The ability to achieve highly conductive nitride ultrathin films by harness strain-controlling over competing phases can be used for utilizing their exceptional characteristics., Comment: 24 pages, 5 figures

Future mobile communication networks require an Aerial Base Station (ABS) with fast mobility and long-term hovering capabilities. At present, unmanned aerial vehicles (UAV) or drones do not have long flight times and are mainly used for monitoring, surveillance, and image post-processing. On the other hand, the traditional airship is too large and not easy to take off and land. Therefore, we propose to develop an "Artificial Intelligence (AI) Drone-Cruiser" base station that can help 5G mobile communication systems and beyond quickly recover the network after a disaster and handle the instant communications by the flash crowd. The drone-cruiser base station can overcome the communications problem for three types of flash crowds, such as in stadiums, parades, and large plaza so that an appropriate number of aerial base stations can be accurately deployed to meet large and dynamic traffic demands. Artificial intelligence can solve these problems by analyzing the collected data, and then adjust the system parameters in the framework of Self-Organizing Network (SON) to achieve the goals of self-configuration, self-optimization, and self-healing. With the help of AI technologies, 5G networks can become more intelligent. This paper aims to provide a new type of service, On-Demand Aerial Base Station as a Service. This work needs to overcome the following five technical challenges: innovative design of drone-cruisers for the long-time hovering, crowd estimation and prediction, rapid 3D wireless channel learning and modeling, 3D placement of aerial base stations and the integration of WiFi front-haul and millimeter wave/WiGig back-haul networks., Comment: 6 pages, 11 figures, accepted by 2019 IEEE Globecom Workshops (GC Wkshps): IEEE GLOBECOM 2019 Workshop on Space-Ground Integrated Networks

FeCoCrNiMn high-entropy alloys were produced by mechanical alloying (MA) and vacuum hot pressing sintering (VHPS). Results showed that the nano-crystalline alloy powders were obtained by MA and the corresponding phase structures were composed of FCC matrices and low amounts of BCC and amorphous phases. After VHPS, the BCC phases almost disappeared, simultaneously with the precipitation of σ phases and M 23 C 6 carbides. An increase of sintering temperature resulted in grain growth of the precipitated phases. As the sintering temperature was increased from 700 to 1000 °C, the strain-to-failure of the alloys rose from 4.4% to 38.2%, whereas the yield strength decreased from 1682 to 774 MPa. The bulk FeCoCrNiMn HEAs, consolidated by VHPS at 800 °C and 900 °C for 1 h, showed relatively good combination of strength and ductility.

Monoclinic rod-shaped ZrO2 whiskers were prepared in liquid conditions using a sulfate flux with ZnSO4 and Na2SO4 in an alumina crucible. TG-DSC, XRD, SEM, TEM, HRTEM, SAED and EDS were employed to characterize the structure, morphology and growth mechanism of the as-synthesized whiskers. The results demonstrated that both the heating temperature and holding time influence the formation of ZrO2 whiskers. When the heating temperature and holding time were 900 °C and 30 min, the ZrO2 whiskers were elongated along the [ 0 1 ¯ 1 ] direction, had an average length and diameter of 600 nm and 70 nm, and exhibited a well-crystallized, one-dimensional structure and smooth surface with no distinct defects. The growth of the whiskers was dominated by the liquid-solid (LS) growth mechanism, affording anisotropic growth through dissolution/recrystallization.

N-Nitrosamines are strong carcinogens and widely existing in nature and human environment. Airborne N-nitrosamines are found in tobacco, rubber factories and heavily polluted areas with atmospheric particulate matter. In this paper, needle trap device, an extraction trap device with sorbent inside the needle, coupled with gas chromatography–mass spectrometry, was applied as an efficient and solvent-free method for the sampling and the determination of four volatile N-nitrosamines (i.e., N-nitrosodimethylamine, N-nitrosodiethylamine, N-nitrosodi-n-propylamine, and N-nitrosodi-n-butylamine) in the atmosphere. The extraction and desorption conditions were selected within the study. Good linearity and recovery values were obtained in the range of 50–3000 ng L−1, and limits of detection of the method were within the range of 1.0–10.0 ng L−1. Finally, the proposed method was successfully applied in sampling and analyzing volatile N-nitrosamines in a local smoking room, and the highest concentration of N-nitrosodimethylamine detected was 2954 ng L−1. We suppose that the results may be meaningful for those suffering from second-hand smoke.

The structural transformation and mechanical properties of fullerenes under high pressure have attracted a significant interest. However, the research data on the large-cage endohedral metallofulle...

An experiment was carried out to investigate the influence of CaCO3 and SiO2 additives on the magnetic and physical properties of M-type Sr ferrites by changing experimental parameters such as the additive composition and Ca/Si ratio. Specimens were prepared by conventional ceramic techniques. It was found that the magnetic properties (Br = 4.42 kG, iHc = 3.32 kOe and (BH)max = 4.863 MGOe) were considerably improved upon adding CaCO3 = 1.1% and SiO2 = 0.4 wt% together with Co3O4, and the mechanical properties thereof were acceptable for motor applications. It was revealed that CaCO3 and SiO2 additives led to an upswing in the magnetic properties via the enhancement of uniform grain growth, particle alignment, and the densification of Sr ferrite.

To improve the yield strength of an FeCoCrNiMn high-entropy alloy (HEA), elemental Ti and C were doped into the alloy. Subsequently, an in situ synthesized carbides particle-strengthened HEA matrix composite was prepared by mechanical alloying (MA), followed by a vacuum hot-pressing sintering (VHPS) method. The TiC nanoparticles were distributed along the grain boundaries. The microstructure of the alloy contained a face-centered cubic (FCC) solid solution as the matrix phase and small amounts of TiC, M23C6 and M7C3 (where M = Cr, Mn, Fe) carbides. The addition of elemental Ti and C significantly improved the room-temperature compressive yield strength of the FeCoCrNiMn HEA from 774 MPa to 1445 MPa (an 86.7% increase), accompanied by a decrease in the compressive strength and plasticity. Grain boundary strengthening and precipitation strengthening are the main strengthening mechanisms of the alloy doping with elemental Ti and C.

The effect of specific surface area (SSA) of Fe 2 O 3 was investigated while evaluating the raw material of Y 3 Fe 5 O 12 (yttrium iron garnet (YIG)) preparation. For YIG ferrite, the specific surface area of Fe 2 O 3 , rather than average particle size ( D 50 ), was found to markedly affect the mixing homogeneity of powders in the mixing procedure and the magnetic properties. Increasing the specific surface area of Fe 2 O 3 resulted in the increase of the remanence ( B r ) and squareness ratio ( SQR ); meanwhile, it also caused an obvious reduction in coercivity ( H C ) for the sintered specimens. An upgrade in the specific surface area of raw material Fe 2 O 3 could further resulted in a decrease in slurry viscosity in the mixing procedure, which promotes slurry mixing homogeneity and further promotes reactivity in the calcination and sintering processes. Consequently, a larger B r and SQR and a smaller H C were obtained. In addition, good ferromagnetic resonance (FMR) line width (i.e., Δ H ) properties were also realized as 36.7 Oe at 3.2 GHz using the selected Fe 2 O 3 . As found in this study, the strict control of raw material Fe 2 O 3 is critical in tailoring suitable B r and H C for the YIG ferrite manufacturing process.

Diamond anvil cell techniques are now well established as a powerful and wide useful method to measure the properties of materials in the very high pressure experiment. However, the measurement of material resistance at the high pressure in the experiment is a big challenge because the electrodes are difficult to be made on the diamond anvil with small top area of the 0.3 mm diameter and have good contact with the sample under the extreme high pressure conditions. In this paper, a new method is used to fabricate the microelectrodes on the diamond anvil surface for the high pressure experiment. Firstly, a special Nickel shadow mask with the electrode patterns, which is made by micro-fabrication technology, is installed and fixed onto the diamond anvil surface with the glue by aligning the electrodes of the shadow mask with the center of the diamond anvil under the microscope. Then, the metal film is deposited onto the anvil with nickel shadow mask by magnetron sputtering. Finally, the microelectrodes having the same patterns with the hollowed structures of the shadow mask can be made with the sputtering material to adhere on the diamond anvil surface after the removal of the shadow mask off the anvil. This new method is simpler, easier to be operated, and less pollution produced to the diamond anvil cell than the traditional method.

Most of multi-component high entropy alloys (HEAs) are only based on metal elements and rarely added with nonmetallic elements. In present paper, CoCrFeNiMn HEA added with 0.1 at.% N has been successfully synthesized by mechanical alloying (MA) followed by vacuum hot pressing sintering (VHPS). During the MA process, the alloying elements were gradually alloyed and formed as face-center (FCC) solid solutions. Subsequently, σ phases, Cr2N phases, FCC matrix phases with traces of Cr23C6 carbides were observed after VHPS. In comparison with CoCrFeNiMn HEA produced by the same method, the Vickers hardness increased up to 468HV, while the yield stress, ultimate compressive strength increased by 203 MPa and 115 MPa respectively, accompanied by a small decrease in plasticity. This demonstrates that adding N element is a viable approach for properties enhancement of HEAs.

Changes in the atomic structure and mechanical properties of rare earth-based metallic glasses caused by destined high-pressure torsion (HPT) were studied by X-ray diffraction synchrotron radiation and nanoindentation. Results showed that destined HPT improved nanohardness and wear resistance, which indicated the significant contributions of this technique. The diffraction patterns showed that the contents of pairs between solvent and solute atoms with a large negative mixing enthalpy increased, whereas those of pairs between solvent atoms and between solute atoms decreased after destined HPT. Thus, the process was improved by increasing the proportion of high-intensity pairs between solvent and solute atoms.

(100-x)(Ge23Se67Sb10)-xI (x = 0, 3, 5, 7, 10 wt%) chalcohalide glasses were prepared by the traditional melt-quenched method. The structure and physical properties were analyzed by using XRD, TMA, FTIR and Vickers hardness tester. It was found that the glass structure trends to crystallization with increase of iodine content. The values of infrared transmittance decrease from 62% to 35% in the range of 2.5–16 μm with increasing iodine content. The density decreases from 4.62 ± 0.3 g cm−3 to 4.31 ± 0.3 g cm−3, the hardness decreases from 164.9 ± 0.5 kg mm−2 to 154.6 ± 0.5 kg mm−2. The glass transition point Tg decreases from 267 °C to 205 °C, while the thermal expansion coefficient increases with iodine content.