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With the development and the progress of science and technology, the spread of rumors presents new characteristics. The spreaders publish false and malicious rumors on public social networks media, and individuals visit these networks and share them with their friends through the friendship network, which provides a convenient hotbed for the indiscriminate spread of rumors. In this paper, an improved rumor spreading model is established to explore the new characteristics of rumor spreading process on the basis of considering the delay of interactive system. By studying the dynamic behavior of the delay spreading model, we calculate the threshold of rumor spreading extinction, and prove the local and global asymptotic behavior of the boundary equilibrium point and endemic equilibrium point of the model. On this basis, we further consider the control strategies such as deleting rumor posts, popular science education, immunotherapy, etc., and propose an optimal control problem to minimize the spread scale and control cost of rumors. The optimal condition of the optimal control problem is calculated by mathematical analysis, and the correctness of the theoretical results is verified by numerical simulations. Finally, we compare the influence of time delays, optimal control and the media network on rumor spreading.

When the pantograph of a high-speed train is separated from the power supply line, a panto-graph-catenary arc (PCA) occurs. This generates electromagnetic interference (EMI) and additional undesired effects on the electrical equipment (such as speed sensors) on the train. It creates a safety hazard for high-speed train operation. This article presents a new method for dealing with EMI caused by the PCA on speed sensors of high-speed trains. The proposed method consists of carrying out an in-depth analysis of the different coupling modes of EMI to identify the corresponding interference suppression measures. Thus, the safety of train operation can be ensured. By changing some relevant parameters, the proposed method can also be applied to other types of trains and electrical equipment.

The metal oxide/nitrogen-doped carbon (NC) compounds zirconium oxide/NC (ZrO2/NC) and cerium oxide/NC (CeO2/NC) were synthesized via the pyrolysis of polyaniline on the metal oxide surface. The characterization of the ZrO2/NC and CeO2/NC catalysts showed more active CO2 reduction reaction activity than that of NC catalyst without metal oxide. Gas chromatography analysis revealed that CO and H2 were the primary products, and no liquid-phase products were detected via proton nuclear magnetic resonance spectroscopy or high-performance liquid chromatography. The maximum Faraday efficiency of ZrO2/NC reached 90% at − 0.73 V (vs. RHE), with the current density of CO at 5.5 mA/cm2; this Faraday efficiency value was higher than that of NC (41%), with the current density of CO at 3.1 mA/cm2. The interaction between the metal oxide and carbon allowed the efficient formation of defect sites, especially imine-type nitrogen, strengthening the adsorption of the key reaction intermediate CO2•− and thus promoting the CO2 reduction reaction.

For the speed regulation problem of a permanent magnet synchronous motor (PMSM), a new class of finite-time control algorithms is designed and utilized to improve PMSM system's dynamical performance and disturbance rejection ability. Specifically, based on a second-order model of the speed regulation system, a bounded finite-time control algorithm is first proposed to conquer the saturation constraint for the considered system. Rigorous theoretical analysis based on the Lyapunov stability theory is provided to demonstrate the finite-time stability of the closed-loop system under consideration. Meanwhile, to improve the disturbance rejection ability of the PMSM system in the presence of disturbance load torque, an improved bounded finite-time controller based on disturbance estimation compensation is further designed. Since the effect of a disturbance signal can be rejected by using feedforward compensation, the improved bounded finite-time controller could offer a better disturbance rejection performance. Finally, numerical simulations and experimental results are provided to verify the effectiveness and advantages of the proposed bounded finite-time control method.

In this article, a new kind of robust digital sliding mode controller is developed to stabilize the output of a class of second-order uncertain systems and is then applied to pulsewidth modulation-based dc–dc buck-type converters with unknown loads and uncertain components. To facilitate the theoretical analysis, a traditional discretized sliding mode controller is first proposed and utilized to such buck-type converters. Theoretical analysis indicates that there is certain steady-state error for the output of the closed-loop systems under such a discretized sliding mode controller. The main reason for the existence of unsatisfactory steady-state error is that the mismatched uncertainties cannot be fully suppressed by the feedback signals from input channels. Motivated by this observation, a new kind of discretized sliding mode controller with disturbances compensation is further proposed and employed to ensure that the steady-state error for the output of the closed-loop uncertain systems can be efficiently eliminated. The robustness of the two discretized sliding mode controllers against component uncertainties and load variations for buck-converters is tested by numerical simulations and experimental studies.

For the attitude tracking of quad-rotor system in the presence of disturbances and input saturation, an active finite-time disturbance rejection control method is presented in this paper. Specifically, first, based on a second-order attitude model of quad-rotor in the absence of disturbances, a bounded finite-time attitude control algorithm under input saturation is proposed to conquer the saturation constraint for practice system. At the second step, considering the existence of disturbances including constant disturbances or time-varying disturbances, a finite-time disturbance observer is designed to estimate the disturbances. Finally, using the idea of active disturbance rejection, the disturbance is directly compensated through the control input channel in the case of constant disturbance. In the case of time-varying disturbance, an integral sliding mode control method is employed here to handle the disturbance estimating error. Rigorous theoretical analysis is provided to prove that the desired attitude can be tracked in a finite time no matter what kinds of disturbances. Simulation results are given to verify the effectiveness and advantages of the the proposed active finite-time control method.

The main objective of this article is to explore the issue of how to improve the performance of discrete-time sliding mode control (DSMC) law for a class of discrete-time dynamic systems with both matched and mismatched disturbances. By using tools from mismatched disturbance compensation technique, a new kind of discrete-time sliding surface is constructed and subsequently utilized in designing the desirable DSMC laws. Specifically, two different types of DSMC laws, i.e., the equivalent-control-based DSMC law and the reaching-law-based DSMC law, are respectively constructed based upon the developed sliding surface. Rigorous analysis on stability of the corresponding closed-loop system is performed where it is shown that the mismatched disturbances could be successfully attenuated from the output channel in steady state. The effectiveness of the analytic result is supported by the experimental studies as well as numerical simulations.

Infectious diseases such as Listeria monocytogenes infection pose a great threat to the health of human beings and the development of livestock and poultry farming. Currently the treatment of Listeria infection mainly relies on antibiotics, which may result in excessive antibiotic residues in livestock and poultry products, as well as causing an increase in the occurrence of zoonotic diseases. Here, we demonstrate that Succinoglycan Riclin promoted the clearance of Listeria in the in vitro and in vivo infection model. The expression and secretion of inflammatory cytokines including IL-6 and IL-1β were significantly increased after Riclin treatment upon infection. The protective effect of Riclin was mainly through activating MAPK/IL-6 axis. HO-1/IL-1β signaling pathway was less important in this process. Moreover, Riclin caused significant metabolic changes including pathways involved in glycolysis, protein synthesis and oxidative stress during Listeria infection. These results suggest a potential use of Succinoglycan Riclin as non-antibiotic preventive and therapeutic anti-microbial agent in livestock and poultry farming and human diseases.

Data center networks employ parallel paths to perform load balancing. Existing traffic splitting schemes propose weighted traffic distribution across multiple paths via a centralized view. An SDN controller computes the traffic splitting ratio of a flow group among all the paths, and implements the ratio by creating multiple rules in the flow table of OpenFlow switches. However, since the number of rules in TCAM-based flow table is limited, it is not scalable to implement the ideal splitting ratio for every flow group. Existing solutions, WCMP and Niagara, aim at reducing the maximum oversubscription of all egress ports and reducing traffic imbalance, respectively. However, the transmission time of flow groups, which measures the quality of cloud services, is sub-optimal in existing solutions that ignore heterogeneous network bandwidth. We propose and implement NAMP, a multipathing scheme considering the network heterogeneity, to efficiently optimize the transmission time of flow groups. Experimental results show that NAMP reduces the transmission time by up to 45.4% than Niagara, up to 50% than WCMP, and up to 60% than ECMP.

Multicast routing in inter-datacenter wide area networks is to compute a multicast tree from a source datacenter to multiple destination datacenters. Software-defined networking enables optimal delay-sensitive routing for multicast sessions in inter-datacenter WANs. Delay-sensitive routing requires the controller to obtain the up-to-date latency of every link. However, the communication overhead and time for collecting the latency information of all links can be prohibitively high for the controller to perform real-time scheduling in a WAN. Inspired by the sparsity of link load information in WANs, we propose compressive latency monitoring , a real-time method for collecting a near-accurate latency information of all links. The controller only needs to collect the latency information of a small subset of significant links and then estimates the latency information of insignificant links. We use real-world network topologies to simulate multicast routing both under the compressive latency monitoring and global latency monitoring. Simulation results show that the compressive latency monitoring can achieve nearly good network throughput performance as the global monitoring with much less communication overhead and in a more timely fashion.

The problem of current sharing controller for parallel dc–dc buck converter system is investigated in this paper. Specifically, to achieve the goal of sharing control and improve the systems dynamic performance, a new finite-time current sharing control algorithm is designed and employed. Under the proposed control algorithm, rigorous proofs show that not only the output voltage of the converter system can reach the desired reference voltage in a finite time, but also the objective of current sharing can be achieved within almost the same time. In addition, when the external load is time-varying and unknown, a finite-time load estimator is given to handle the load variation, and an adaptive finite-time current sharing control algorithm is subsequently developed. Experimental results are presented to verify the effectiveness of the proposed method, and to show its advantages over some traditional control algorithms. It is shown that a faster convergence rate and a better load disturbance rejection performance can be yielded by the present algorithm. Finally, it is shown that the main results can be extended to the case of $n$ parallel dc–dc buck converters.

Hybrid software-defined network (SDN) is a network where legacy routers and SDN routers coexist during the incremental deployment of SDNs. The existing SDN router placement methods mainly focus on maximizing the traffic engineering performance under a limited budget. Traffic engineering requires real-time link-load information. However, the latency for collecting the global link-load information can be prohibitively long in a wide area network due to the long interior gateway protocol convergence time. Inspired by the sparsity of the link load, we propose a novel compressive traffic monitoring method for collecting real-time load information of all links. In this method, the controller only needs to collect the load of a small subset of important links and then estimates the link load of the rest. The minimal number of SDN routers is placed to cover these important links. We use real-world topologies and traffic matrices to evaluate our method. Experiment results show that our method can quickly estimate the global link load at an error rate of 5% within sub-seconds. Compared with the state-of-the-art methods, our method has better adaptability to the dynamic traffic changes and can reduce the maximal link usage by 39%.

In this paper, the current-constrained problem is studied. In order to track the voltage to the reference voltage quickly, a finite-time control algorithm is designed. Meanwhile, considering that when the voltage changes rapidly, the current in the circuit will increase, which will cause damage to the devices in the circuit. Thus, a current-constraint algorithm must be applied to the controller. The controller designed in this paper can achieve stability in finite-time, and the correctness of the control algorithm is proved. Next, the simulation is carried out to verify the dynamic and steady-state performance of the proposed method.

The finite-time tracking control problem via output feedback for a nonholonomic wheeled mobile robot with a higher-order dynamic model is investigated in this paper. To solve the problem when the robot's velocities cannot be measured, some coordinate changes are skillfully introduced at the first step. Then based on the fast finite-time control algorithm, a fast finite-time state feedback controller is designed and then a fast finite-time observer is constructed. Finally, an observer-based dynamic output feedback controller is proposed, which can guarantee that the reference trajectory can be tracked in a finite time through a rigorous stability analysis. An example is given to verify the efficiency of the proposed method.

The wireless network that integrates a heterogeneous cellular network and a WLAN is referred to as a WLAN/cellular integrated network (WCIN). In a fourth generation WCIN, in order to achieve collision-avoidance between the LTE-A and IEEE 802.11 family, some interference-free mechanisms, such as carrier sense adaptive transmission and listen-before-talk, are proposed. However, the interference-free medium access mechanisms leave some unexploited partially overlapped 802.11ac channels, which result in a waste of spectrum. In this paper, we propose an interference-tolerant medium access method to optimize the WCIN throughput by utilizing those partially overlapped channels (POCs). First, we show the feasibility of enhancing WLAN throughput by utilizing 802.11ac POCs in a WCIN. Second, we mathematically model the partial overlap when an 802.11ac channel is partially overlapping with an LTE-A component carrier. Third, we propose an interference-tolerant medium access mechanism to optimize the WCIN throughput. The interference-tolerant one ensures that the interference to LTE-A users is tolerable in a given WCIN. Finally, we construct a hardware-in-the-loop testbed to evaluate and compare our proposed mechanism with three other state-of-the-art mechanisms. The experimental results show that our approach achieves at most 39% more throughput than one of the state-of-the-art collision-avoidance mechanisms regarding the entire WCIN.

A new voltage regulation control algorithm is designed for the buck-type dc-dc converter system in the presence of unknown input voltage and load variations. To enhance the voltage regulation time by using the finite-time control theory, a new fast voltage regulation control algorithm is designed that can guarantee that the output voltage converges to the reference voltage in a finite time. To address the unknown input voltage and load variations, two finite-time convergent observers are designed to estimate the unknown parameters in a finite time. Finally, an adaptive finite-time control algorithm is developed. Compared with the PI control algorithm, experimental results show that the proposed algorithm has a faster regulation performance and stronger performance on load-variation rejection.

Summary To enhance the convergent rate and robustness of buck-type DC-DC converter system, a new finite-time voltage regulation control algorithm is proposed in this paper. First, an average state space-based model is analyzed, which considers both the parameters uncertainties and the variations of load and input voltage. By using saturation finite-time control theory, at the first step, in the absence of disturbance, a new fast voltage regulation control algorithm is designed, which can guarantee that the output voltage converges to the reference voltage in a finite time. Because the saturation constraint is considered during the controller design, the duty ratio function of the converter satisfies the constraint between 0 and 1. Second, in the presence of disturbance, a finite-time convergent disturbance observer is designed to estimate the unknown disturbances in a finite time. Finally, a disturbance observer-based finite-time voltage regulation control algorithm is developed. Compared with PI (Proportional-Integral) control algorithm, circuit simulations show that the proposed algorithm has a faster regulation performance and stronger robustness performance on disturbance rejection.

In this paper, a finite-time controller is proposed for the quadrotor aircraft to achieve hovering control in a finite time. The design of controller is mainly divided into two steps. Firstly, a saturated finite-time position controller is designed such that the position of quadrotor aircraft can reach any desired position in a finite time. Secondly, a finite-time attitude tracking controller is designed, which can guarantee that the attitude of quadrotor aircraft converges to the desired attitude in a finite time. By homogenous system theory and Lyapunov theory, the finite-time stability of the closed-loop systems is given through rigorous mathematical proofs. Finally, numerical simulations are given to show that the proposed algorithm has a faster convergence performance and a stronger disturbance rejection performance by comparing to the PD control algorithm.

A Partially Overlapped WiFi Channel (POC) is a type of WiFi channel whose spectrum is partially overlapping with other carriers. It has been empirically demonstrated that the throughput of heterogeneous cognitive network can be improved by utilizing POCs. POC detection is a prerequisite to POC utilization. Unfortunately, the existing Clear Channel Assessment (CCA) methods such as energy-based detection and preamble detection cannot accurately detect the POC in heterogeneous cognitive networks. As a result, POCs will not be used by most WiFi users. The spectrum in POCs is therefore under-utilized and wasted. In this article, we propose to detect a POC by statistically analyzing the bit-level information inside the payload of WiFi frames. The proposed approach is based on a series of measurements on bit errors under real-world IEEE 802.11ac channels. A POC can be accurately detected by analyzing the correlation between an unknown WiFi channel and a given POC in terms of their bit-error vectors. Our approach is evaluated by detecting fifty $\frac{1}{2}$ -overlap WiFi channels among a hundred different real-world WiFi channels. The final results show that, our approach can achieve an accuracy of 96% and a false positive rate of 8% on POC detection, which is much better than the existing CCA methods.

The problem of finite-time attitude regulation for multiple rigid spacecraft with leader-follower architecture is studied. The desired attitude for spacecraft formation is represented by the attitude of a leader. A distributed finite-time convergent observer is first proposed to estimate the leader's attitude in a finite time. By using the technique of finite-time saturation control, a bounded finite-time attitude controller is designed to track the estimated attitude and then the leader's attitude in a finite time. A simulation example is finally given.

Carbon dioxide electroreduction to oxalate suffers from low selectivity and large overpotential. This study used lead tin oxide nanoparticles for selective oxalate generation with low overpotential in propylene carbonate. The maximum Faradaic efficiency of 85.1 % have been reached by PbSnO3/C at −1.9 V vs Ag/Ag+ with oxalate current density of 2.0 mA/cm2 on carbon fiber paper. The notable activity for CO2 electroreduction to oxalate was attributed to the synergistic effect of partially reduced Pb and oxidized SnOx composites in lead tin oxides.

The distributed fixed-time consensus problem for a class of heterogeneous nonlinear leader–follower multi-agent systems is investigated in this paper. The considered multi-agent systems comprise several first-order nonlinear systems and second-order nonlinear systems of which the inherent nonlinearities are allowed to be lower-order and higher-order. By designing distributed fixed-time observers and fixed-time tracking controllers, it is theoretically shown that distributed consensus for the heterogeneous nonlinear multi-agent systems can be achieved in a fixed time, i.e., the achievement time for consensus is independent of any initial states. A simulation example is provided to show the effectiveness of the designed consensus controllers.

Summary The second-order consensus problem of nonlinear leader-following multi-agent systems is investigated in this paper. To solve the case that the velocities of all agents cannot be measured and the nonlinearity is unknown, an observer-based dynamic output feedback controller is proposed based on a non-separation principle method. Using the feedback domination technique, it is shown that the systems output can reach consensus by choosing appropriate gains. Two examples are given to verify the efficiency of the proposed method. Copyright © 2015 John Wiley & Sons, Ltd.

The consensus problem of multiple nonholonomic mobile robots in the form of high-order chained structure is considered in this paper. Based on the model features and the finite-time control technique, a finite-time cooperative controller is explicitly constructed which guarantees that the states consensus is achieved in a finite time. As an application of the proposed results, finite-time formation control of multiple wheeled mobile robots is studied and a finite-time formation control algorithm is proposed. To show effectiveness of the proposed approach, a simulation example is given.

The operation error of the electric energy metering device directly affects the accuracy of the electricity trade calculation, so it's very important to ensure the device working accurately. Based on the electric energy meter condition assessment model, considering economic benefits, management benefits and social benefits, we use fuzzy analytic hierarchy process to establish a rotation meter benefit assessment model. Using this model calculate the rotation benefit score. Thus the corresponding rotation strategies for electric energy meter were established. This method has better adaptability than the traditional management approach. By means of quantitative analysis of scientific results, the cycle of rotation, rotation adjustment strategy accordingly, more objective and reasonable than traditional management.

Nowadays, many organizations or corporations, such as banks, hospitals, schools, etc., use third-party platform to send notifications or information to their customers or users. This communication model can be generalized to the publish/subscribe model. The publisher will send the content to the subscriber whenever there is any new content that matches the interest of the subscriber. However, the content may contain users' privacy which is sent in plain text by the third-party platform. When the platform is not fully trusted, users' privacy is at the risk. In this paper we propose a secure protocol to protect users' privacy against the untrusted third-party platform. Our privacy preserving protocol has three main advantages: 1) There is no need to set up a secure synchronous communication channel between the subscriber and the publisher in our protocol. 2) There is no need to introduce any Certificate Authority (CA) for certifying publishers or subscribers in our protocol. 3) There is no need for subscribers or publishers to remember any additional key for each subscription or publication, which makes our protocol scalable to large pub/sub system.

Near-infrared (NIR) light-responsive liposomes are attractive carriers for targeted and controlled drug delivery to the superficial organ or tissue (e.g., skin). This work describes the development of NIR-responsive liposomes by incorporating gold nanostars within liposomes composed of Phospholipon 90 g and cholesterol. Following cellular delivery, photothermal effect around the gold nanostar upon NIR stimulation induces microcavitation and liposome phase transition which consequently triggers the release of encapsulated molecules. Taking GFP plasmid as an example, we demonstrate enhanced gene transfection into fibroblasts following NIR treatment. Published version

Presents comments on the paper, "Design of voltage tracking control for DC-DC Boost converter via total sliding-mode technique," (Wai, R.J., et al), IEEE Trans. Ind. Electron., vol. 58, no. 6, pp. 2502-2511, Jun. 2011.