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The effects of cryogenic thermal cycling on deformation behaviour and structural variation of {[(Fe0.5Co0.5)0.75B0.2Si0.05]96Nb4}99.9Cu0.1 bulk metallic glass (BMG) were studied and compared with Cu-free [(Fe0.5Co0.5)0.75B0.2Si0.05]96Nb4 BMG. After thermal-cycled treatment between 393 K and cryogenic temperature, the {[(Fe0.5Co0.5)0.75B0.2Si0.05]96Nb4}99.9Cu0.1 BMG obtained a plastic strain of 7.4% combined with a high yield strength of 4350 MPa. The excellent soft magnetic properties were maintained after CTC treatment. The minor addition of Cu element results in an initial nano-sized heterogeneity in the matrix, which facilitates the rejuvenation process during thermal cycling, and brings to a low optimal thermal temperature of 393 K, making the {[(Fe0.5Co0.5)0.75B0.2Si0.05]96Nb4}99.9Cu0.1 BMG more attractive in industrial application. During thermal cycling, the formation of more soft regions leads to the increase of structural heterogeneities, which is beneficial to the initiation of shear transition zones and the formation of multiple shear bands, and thus results in the enhancement of plasticity. This study links the subtle variation of specific structure with macroscopic mechanical properties, and provides a new insight of composition selection for cryogenic thermal cycling treatment.

The effects of dual Zr and O plasma immersion ion implantation (Zr & O PIII) on antibacterial properties of ZK60 Mg alloys are systematically investigated. The results show that a hydrophobic, smooth, and ZrO2-containing graded film is formed. Electrochemical assessment shows that the corrosion rate of the plasma-treated Mg alloy decreases and the decreased degradation rate is attributed to the protection rendered by the surface oxide. In vitro and in vivo antibacterial tests reveal Zr & O PIII ZK60 presents higher antibacterial rate compared to Zr PIII ZK60 and untreated control. The hydrophobic and smooth surface suppresses bacterial adhesion. High concentration of oxygen vacancies in the surface films are determined by X-ray photoelectron spectroscopy (XPS), UV–vis diffuse reflectance spectra (UV–vis DRS) and electron paramagnetic resonance (EPR) and involved in the production of reactive oxygen species (ROS). The higher level of ROS expression inhibits biofilm formation by down-regulating the expression of icaADBC genes but up-regulating the expression of icaR gene. In addition, Zr & O PIII improves cell viability and initial cell adhesion confirming good cytocompatibility. Dual Zr & O PIII is a simple and practical means to expedite clinical acceptance of biodegradable magnesium alloys., Graphical abstract Image 1, Highlights • A ZrO2-containing graded film with high concentration of oxygen vacancies was formed via PIII. • S. aureus adhesion was suppressed due to enhanced hydrophobicity and decreased roughness. • High concentration of oxygen vacancies lead to the upregulation of ROS expression. • ROS mediates biofilm-associated genes expression to inhibit biofilm formation in vitro and in vivo.

With the development of both cryogenic and motor pump technologies, the cryogenic variable thrust liquid rocket engines that using motor pumps have gained considerable attention. However, the heavy battery limits its performance if engine operates for high thrust. To address this challenge, the electric expander cycle system scheme for variable thrust liquid rocket engines is creatively proposed and designed. Subsequently, the system parameters are calculated based on mass and energy conservation with chamber heat transfer considered. As well, the distribution of this novel system state parameters is investigated. Further, a comparison is conducted between the electric expander cycle system, electric pump, and expander cycle systems. The comparison results demonstrate that this innovative system scheme has advantages of simple structure, low battery mass, convenient throttling, and high reusability. The system state parameters distribution indicates that the feed system can achieve the propellants' pressurization requirements throughout the designed 5:1 throttle range, which suggests the feasibility of this system scheme. Moreover, although the proposed system requires more battery power than does the turbine, the turbine power proportion in the entire system increases with thrust. However, the turbine efficiency drops steeply with a decrease in thrust, whereas the double pump efficiency presents a narrow variation range.

The large-capacity electrically excited synchronous machines are widely applied in modern industrial production, and starting issues have become one of the most concerns of the synchronous motors in practical operation, such as the long starting time, large current shock, and poor adaption to a wide-ranging load. To deal with these starting problems, many starting methods have been proposed in previous studies. Regrettably, high-performance methods depend on specific motor parameters and complex sensorless technology, while simple and low-cost methods are low performance. In this article, a modified back-to-back starting method is proposed for large-capacity synchronous machines based on virtual synchronous generator (VSG) technology, where the cascaded H-bridge converter is controlled as a VSG to replace the prime mover and synchronous generator of the conventional back-to-back starting system. To reduce the current shock, an initial relative-angle regulator is designed. To improve the robustness in the presence of a wide-ranging load, a damping torque branch is adopted. Extra speed sensors are no longer required since the VSG speed is directly applied in the feedback control loop. To validate the effectiveness of the proposed approach, extensive simulation and experimental results are presented. Compared with conventional approaches, the proposed starting method achieves faster response, smaller starting current, and stronger robustness.

The production of redundant waste heat limits the performance of photovoltaic cells, so removing waste heat and converting it back into electricity is a promising way to improve the utilization of solar energy. A new concentrated solar spectrum photovoltaic-thermophotovoltaic hybrid system mainly is proposed. Full-spectrum solar energy is split into different parts according to specific requirements. Expressions for the efficiency and power output of the system are derived. The effects of the voltage output and area ratio of the two subsystems, the bandgap energy of semiconductor in the photovoltaic cell, and the solar concentration factor on the system performance are analyzed comprehensively. By optimizing several key parameters, the problem of the optimal matching between two subsystems is solved. The performance characteristics of the system are revealed, and the maximum efficiency and corresponding power output density of the hybrid system are calculated numerically, reaching 47.74% and 31.13W cm−2, respectively, which are 9.190% and 19.25% higher than those of a single photovoltaic cell. The optimal selection criteria of several key parameters are provided. By comparison with other PV-based systems, the proposed system not only maintains a high energy conversion efficiency but also produces a relatively larger power output density.

This article aims at identifying the worst-case waveform of a radiated high-power electromagnetic (HPEM) for maximizing threats to the victim electric system. In contrast to the previous analysis where constraint on energy-density of the HPEM field is imposed, the proposed analysis considers an upper bound constraint for the amplitude of the electrical waveform, which appears to be a more concerned restriction for practical radiation system. In this connection, evolutionary algorithms, i.e., genetic algorithm, stud-genetic algorithm (StudGA), and particle swarm optimization, are resorted to for solving the problem. In particular, it is found that StudGA outperforms the other two approaches for solving the proposed problem. The results demonstrate an optimized wideband HPEM is only marginally more threatening to the victim system than an attentively tuned continuous-wave/narrowband interference, and it is a fairly good compromise to apply these fields for the worst-case immunity assessment, especially when the difficulty in generating wideband HPEM of complex waveform details is considered.

We propose a recursive constrained least lncosh (RCLL) adaptive algorithm to combat the impulsive noises. In general, the lncosh function is used to develop a new algorithm within the context of constrained adaptive filtering via solving a linear constrained optimization problem, where the lncosh function is a natural logarithm of hyperbolic cosine function, which can be regarded as a combination of mean-square-error (MSE) and mean-absolute-error (MAE) criteria. Compared with other typical recursive methods, the proposed RCLL algorithm can obtain superior steady state behavior and better robustness for combating impulsive noises. Besides, the mean-square convergence condition and theoretical transient mean-square-deviation of the RCLL algorithm is presented. Simulation results verified the theoretical analysis in non-Gaussian noises and shown the superior performance of the proposed RCLL algorithm.

In this brief, we proposed a recursive constrained maximum $q$ - $\text{R}\acute {\text e}$ nyi kernel (RCMqR) adaptive filtering algorithm, which is derived via introducing a $q$ - $\text{R}\acute {\text e}$ nyi kernel function into constrained adaptive algorithm and using $q$ - $\text{R}\acute {\text e}$ nyi kernel function to construct a new cost function and providing its recursive form to create a linear constrained filter. The created RCMqR algorithm can achieve superior performance compared with other conventional algorithms under non-Gaussian noises environment. Theoretical transient mean-square deviation (MSD) of the RCMqR algorithm is presented when the system background noises are Gaussian-noise and non-Gaussian noise, and a sufficient condition has been achieved to make sure RCMqR algorithm converge. Various computer simulations are performed in system identification for the purpose of comparison. The simulation results verified that the theoretical analysis match well with the simulations and the proposed algorithm has better robustness than other algorithms under non-Gaussian impulsive noise.

This article proposed a modified electromagnetic field coupling to transmission line (TL) model with the objective to accounting for the impact of complex dielectric coatings. Classic TL model neglects the perturbation effects of coatings on the incident electric field; the validation of this simplification is disproved in this article for TL structure with complex dielectric coatings. Through analysis, it is corroborated that coating effect could be neglected only for longitudinal electric field component, whereas the perturbation on transverse field component needs to be taken into account by a newly introduced parameter called coating coefficient. The proposed method is verified through a case study on a differential line system, where a simulation method based on the 2-D finite element method is also proposed to evaluate the value of the coating coefficient.

With the increasing complexity of wind turbines, the current situation of high failure rates and high maintenance costs has attracted the attention of wind power operators. The research on the heal...

Objectives Since DHZCP had significant inhibitory effects on liver and kidney fibrosis, we hypothesize that DHZCP could also inhibit pulmonary fibrosis. Therefore, the aim of this study is to examine the effect of DHZCP on silicosis, a type of pulmonary fibrosis caused by silica dust, and its underlying mechanism. Methods Pulmonary fibrosis was induced by inhalation of silica (SiO2) dust in mice which were then randomly divided into 5 groups: pulmonary fibrosis model group, high-dose DHZCP group, medium-dose DHZCP group, low-dose DHZCP group and Tetrandrine group. The normal control group mice were not exposed to SiO2 dust. After 28 days of continuous intragastric administration of DHZCP, the mice were sacrificed. The histopathology of lungs, the levels of tumor necrosis factor alpha (TNF-α), interleukin-6 (IL-6), interleukin-1β (IL-1β) and hydroxyproline (HYP) in serum. Besides, the expression of transforming growth factor‑β1 (TGF-β1), α-smooth muscle actin (α-SMA), Smad2, Smad3 and Smad7 in lung tissue were examined. Results The mice with silicosis was generated with an observed inflamed lung tissues and elevated inflammatory cytokines. DHZCP significantly reduced serum levels of TNF-α, IL-6, IL-1β and HYP in mice with lung fibrosis. DHZCP treatment remarkably downregulated mRNA and protein levels of TGF-β1, α-SMA, Smad2 and Smad3 in lung tissue, while increased the protein level of Smad7. Conclusions These results demonstrated that DHZCP could alleviate pulmonary fibrosis induced by SiO2. The anti-fibrotic effects of DHZCP are conferred by decreasing inflammation and pulmonary fibrosis, which may be related to the TGF-β1/Smad pathway.

In this letter, we consider the scenario that a linearly polarized electromagnetic plane wave excites a transmission line (TL). By tailoring the reciprocity theorem for modeling the field-coupling problem, we prove that the maximal/minimal coupling scenarios can be determined from the radiation pattern data. Particularly, the incidence and polarization angles of the field that maximize/minimize the coupling efficiency of a matched TL are solved in a closed form. Accordingly, design guidelines have been proposed for the protection of TL from electromagnetic interferences.

In this letter, we investigate the beamforming optimization problem in a non-orthogonal multiple access (NOMA) based multibeam satellite system. The design key is to minimize the transmit power on-board the multibeam satellite system with the perfect and imperfect channel state information (CSI), while meeting the quality of service (QoS) for satellite users. Owing to the intractability and non-convexity of the original optimization problem induced by the user’s CSI uncertainty, we consider the robust beamforming scheme to convert the original optimization problem into a tractable convex optimization problem by S-Procedure and semidefinite relaxation (SDR) techniques and obtain the optimal solutions. Finally, numerical simulations demonstrate the superiority and validity of the proposed beamforming optimization algorithms.

A case of the absorption of corona virus disease 2019 (COVID-19) promoted by professor Xu ZOU's acupuncture technique for "benefiting kidney and strengthening anti-pathogenic qi" is introduced. A female patient suffered from COVID-19, 64 years old, had been treated with acupuncture and Chinese herb granules for 10 days on the base of the oral administration of moxifloxacin. In the re-examination, the chest CT image indicated that the absorption of COVID-19 was obvious as compared with before, the nucleic acid test of novel corona virus was negative and the patient narrated no obvious discomfort. Acupuncture therapy plays its active adjuvant effect in the whole process of the treatment of COVID-19.

Adenosine has received great attentions acting as a potential biomarker for monitoring lung cancer. Most of the reported studies for adenosine detection require large instruments and complicated procedures. Herein, a sensitive, rapid and in-situ colorimetric aptasensor was developed for adenosine detection. Moreover, a homemade biomimetic electronic-eye (E-eye) was established and utilized as a portable in-time detection equipment. The entire measurement can be completed within 20 min, including the combination of aptamer with adenosine or AuNPs and the detection of adenosine. Four different kinds of aptamer were compared and the results showed that the AuNPs-aptamer-biotin system was the most stable and with the widest detection range of 5.0 μM–60.0 μM and the lowest LOD of 0.17 μM. Moreover, the artificial urine samples were also tested with a linear range from 5.0 to 50.0 μM and a LOD of 0.48 μM. The results validated that the aptasensor together with the E-eye can be a promising platform for adenosine detection.

The magnesium alloy has a unique advantage in 3C fields due to its high specific strength and excellent electromagnetic shielding characteristic. However, it is difficult to deform homogeneously because of hexagonal close-packed structure. In the present work, the microstructure, mechanical properties and stretch formability of magnesium alloy sheets with different alloying elements were investigated. It was indicated that a trace addition of Zn or/and Er made a key role in modifying texture, activating shear bands formation and precipitating nanoscale second phases, respectively, which resulted in an obvious improvement in both stretch formability and mechanical properties. The results suggested that the Mg–0.5Zn–0.5Er alloy sheet exhibited higher tensile strength along the rolling direction, i.e., yield strength of 180 MPa and ultimate tensile strength of 201 MPa, accompanying with superior Erichsen value of 7.0 mm at room temperature. The good performances of the sheet were ascribed to weakening basal texture intensity, formation of shear bands and precipitation of nanoscale W-phase (Mg3Zn3Er2). The microstructure, mechanical properties and stretch formability of magnesium alloy sheets with different alloying elements were investigated in the present investigation. It was indicated that a trace addition of Zn or/and Er made a key role in modifying texture (Fig. 1), activating shear bands formation and precipitating nanoscale secondary phases (Fig. 2), respectively, which resulted in an obvious improvement in both stretch formability and mechanical properties (Fig. 3).

In this paper, transmission-line (TL) theory is applied to formulate a worst-case analysis for the assessment of wideband intentional electromagnetic interference radiated onto a cable harness (with terminal units) above ground. Given the bandwidth and the energy density of the high-power electromagnetic pulse impinging on the cable, the pulse spectrum maximizing the peak value of the common-mode voltage waveform induced at a cable end is obtained. Unlike in a full-wave solution to the problem, the proposed TL model allows for, first, deriving closed-form expressions in the special case of a cable terminated in a matched load at the opposite end; second, computationally efficient evaluation of the spectrum for any other loading conditions. The obtained results clearly unveil the impact of the system parameters (cable length, height, terminal loads, and pulse bandwidth) on the statistics of the worst-case voltage peak for the random direction of incidence and polarization.

Q&P steels possessing a combination of ultra-high product of strength and tensile elongation (PSE) and superior impact toughness was obtained by tailoring the micromechanical deformation ability of retained austenite (RA) and martensite via low-temperature partitioning. Our results indicate that impact toughness is more susceptible to the heterogeneity of mechanical properties of constituent phases than its tensile mechanical properties. Through optimizing the difference between the constituent phases, the impact toughness can be improved significantly by the enhancement of micromechanical deformation ability of tempered martensite (TM) and corresponding alleviation of deformation incompatibility. Simultaneously, high PSE was preserved by using the deformation potential of RA and its transformation-induced plasticity effect. Load–unload–reload (LUR) tests were carried out to characterize the evolution of flow stress components and the influence of partitioning temperatures on the degree of deformation inhomogeneity between constituent phases during plastic deformation. Furthermore, the mechanical properties and micromechanical deformation ability of the constituent phases were quantitatively characterized using the nanoindentation technique, which indicates that degree of incompatible deformation is alleviated for steels partitioned at relatively high temperatures due to the enhancement of the deformation ability of TM. The underlying relationship between the dynamic transformation of metastable austenite based on the Olson and Cohen model, and high PSE was elucidated. As the partitioning temperature increases, the mechanical stability of RA increases, which is attributed to the synergistic effect of carbon partitioning and the improvement of compatible deformation capability of TM and RA, resulting in an excellent combination of concurrent ductility and impact toughness. Based on the above characterization and analysis, further investigation into the fractured morphology of impact and edge notched specimens was carried out to provide a comprehensive understanding of the damage and fracture mechanism, and to reveal the reasons for the improvement of mechanical properties. The nucleation position and propagation path of microvoids and microcracks depend on the deformation compatibility of constituent phases and the morphology of cementite in tempered martensite. The nucleation sites of microcracks and microvoids at the phase interface, due to stress concentration and dislocation pile-ups for incompatibility deformation of constituent phases, are substituted with nucleation sites at fractured cementite in TM with the increasing partitioning temperature.

In the development of alternative test methods for pre-compliance radiated-susceptibility (RS) investigations, it is proven that a special test setup, involving an additional wire placed in proximity of the cable under test and fed by two radio-frequency generators, can reproduce through crosstalk (XT) the same terminal voltages/currents induced in the standard RS test setup, on condition that those generators are properly controlled in magnitude and phase. Such a test setup does not require expensive facilities like anechoic chambers and powerful amplifiers to feed antennas, therefore it represents a fast and cheap alternative to get feedback on radiated immunity in the early-design stage, before the formal RS assessment carried out according to standards. While in past literature works the equivalence between XT and RS was demonstrated for some simple cables like a single bare wire or a differential pair, this paper presents a new XT-based test setup suitable for the practically relevant case of a complex bundle of dielectric-covered wires. To this aim, two different formulations of feeding conditions are proposed, one more rigorous, based on multiconductor-transmission-line modeling, and one approximate, based on bundle-reduction techniques. The performance of both the equivalence schemes is assessed and discussed in the frequency range between 1 MHz and 1 GHz.

With the continuous elevation of demand for large-scale wind turbines and operation & maintenance cost an increasing interest has been rapidly generated on CM (Condition Monitoring) system. The main components of wind turbines are the focus on all CM as they overall lead to high repair costs and equipment downtime. Thus, it is difficult to make comprehensive assessment in the assessment. In the present study, intelligent machine learning algorithms are adopted to mine SCADA (Supervisory Control and Data Acquisition) system data of WTs (wind turbines). Besides, based on bidirectional long short-term memory (BiLSTM) neural networks and gaussian mixture model (GMM) algorithm, this study developed a multi-running state health assessment model for the drive system of wind turbines. First, the state-identification model is built with health data to overcome the effect of the time-varying characteristics of running environment and alterations of running condition during the assessment. Then, in each state, the BiLSTM algorithm is adopted to extract the residual set of valid state variables, and the GMM algorithm is employed to accurately fit the distribution of residual set. The multi-running state benchmark model based on BiLSTM and GMM is built. Subsequently, the drive system of wind turbines health degree is calculated by health index. Lastly, based on multiple driving system faults data of a wind turbine, the feasibility and validity of the model are verified.

The application of millimeter wave (mmWave) spectrum for the next generation broadband communications has received significant attention recently. In this work, we investigate the performance limits for the coexistence of the geo-stationary orbit (GEO) broadband satellite networks and terrestrial mmWave cellular networks. Based on the assumption that the statistical channel state information (SCSI) is available at the terrestrial base station (BS), we propose a virtual uplink based transmit beamforming (BF) algorithm to maximize the ergodic capacity of the terrestrial user while satisfying the interference probability constraint of the satellite users. Furthermore, we derive the closed-form expressions for the outage probability (OP) and ergodic capacity (EC) of the terrestrial user. Besides, the asymptotic OP expression at high signal-to-noise ratio (SNR) is also developed in terms of diversity order and array gain of the terrestrial user. Finally, numerical results are given to confirm the validity of the proposed BF scheme and theoretical derivations, and reveal the impact of key parameters on the performance of the terrestrial user coexisting with the multiple satellite users.

Hybrid satellite-terrestrial relay network (HSTRN) has been viewed as a flexible and promising solution to be developed with heterogeneous devices and integrated infrastructures for improved coverage and reduced latency. Taking the requirements of overall spectral and power efficiency into account, we consider different adaptive transmission schemes for the hybrid architecture oriented to potential applications in practical scenarios, and obtain the analytical expressions for the achievable channel capacity with respect to different schemes, i.e., optimal power and rate adaptation, and truncated channel inversion and fixed rate. Numerical simulations confirm the validity of the derived theoretical results, and provide useful guidance for emerging applications in HSTRN that are under various fixed/adaptive transmit power or rate requirements.

Hybrid satellite-terrestrial relay network (HSTRN) has been viewed as a flexible solution to be developed with the heterogeneous devices, integrated systems, and infrastructures for future wireless communications. To alleviate the spectrum shortage and meet the requirements of improved spectral efficiency, this letter incorporates the wireless content caching into HSTRN, where two representative cache placement schemes are considered, namely, the most popular content-based scheme, and the uniform content-based caching scheme. Specifically, the analytical expressions for the outage probability of considered HSTRN with different cache placement schemes are derived. Simulation results are provided to validate the theoretical analysis and confirm the substantial performance improvement of proposed schemes over the traditional approach without caching capabilities.

Heavy-metal pollution has attracted intensive attention from the public because of the severe threats of heavy metals to the ecosystem and human health. Ultralow concentration of heavy metals in aquatic environment leads to the urgent needs of sensitive approaches for heavy-metal detection. Electrochemical DNA biosensors present outstanding superiority in convenience, selectivity, and sensitivity compared with conventional methods. To achieve the ultralow detection limit, efforts have been made to implement signal enhancement strategies to develop electrochemical DNA biosensors with enhanced sensing performance. This review focuses on the recent progress in signal enhancement strategies applied to electrochemical DNA biosensors for heavy-metal-ion detection including nicking enzyme–assisted amplification, the utilization of core–shell nanoparticles, and nanocomposites modification.

An automated flow-batch analyzer (FBA) based on spectrophotometry was developed for the determination of nitrite (NO2−) in environmental waters. The FBA consists of a homemade flow cell, light source, detector and a mini-syringe pump, which was controlled by self-designed software written in LabVIEW. Two LEDs and a light-to-voltage converter were used as the light source and detector respectively. The chemical detection method was based on spectrophotometry and modified Griess reaction. With the optimized conditions, the limit of detection (LOD) was 0.018 µmol·L−1 and the relative standard deviations (RSDs) at different concentrations (0–12 µmol·L−1) were 0.54%–3.63% (n=3). Measurements of different aqueous samples (n=21) showed no significant difference between results obtained by developed FBA and a commercial spectrophotometer.

This study deals with intentional electromagnetic interference and presents statistical analysis of common-mode and differential-mode disturbances induced in unshielded or shielded cables by a radiated, wideband, high-power electromagnetic (HPEM) pulse. The quantity of interest is the worst-case (i.e., maximum) peak in the time-domain waveform of the voltage that can be induced in a terminal interface of the harness by an HPEM pulse with specified bandwidth and energy density. Statistics is required to account for the lack of knowledge on the direction of incidence and polarization of the impinging plane-wave field, which are treated as random variables. Consequently, the worst-case induced-voltage peak is characterized by a cumulative distribution function (cdf). The analysis puts into evidence the different properties of the cdf for unshielded and shielded cables, with reference to the influence exerted by the main system parameters, including the cable length, the height above ground, and terminal impedances.

Wireless sensor network can be easily attacked by jammers for its shared character and open access to the wireless channel. Jamming attack could produce a significant threat to the network by interrupting the normal transmission of nodes. To this end, several anti-jamming countermeasures have been proposed to improve the quality of service of the wireless sensor network. As an important building block for anti-jamming countermeasures, the estimation of jammer’s location could provide us a possible way to eliminate jammers artificially. However, existing localization algorithms mainly pay attention to locate the jammers that are equipped with omnidirectional antennas, which usually fail to cope with directional jammers. In order to bridge this gap, an algorithm of antenna identification and localization of the jammer (AILJ) based on the topology information of jamming scenarios is put forward in this paper. At first, a collection protocol is designed to collect the information of boundary nodes and jammed nodes. Then, an identification method based on the classification of the boundary nodes is proposed to derive the type of jammer’s antenna. At last, a range-free method is put forward to locate the jammer without relying on the propagation parameters. The proposed AILJ only depends on the localization of jammed nodes and boundary nodes and employs their geometry knowledge. For the omnidirectional jammer, the mean center of two circumcircles is considered as the jammer’s position. For the directional jammer, the mean value of the intersections between the straight line that represents jammer’s direction and the circumcircles is considered as the directional jammer’s position. Finally, a series of experiments have been conducted to evaluate the identification and localization performance of AILJ.

A multiuser large-scale MIMO system with antenna correlation and mutual coupling is investigated in this paper. Based on the maximum signal-to-interference-plus-noise ratio (SINR) criteria, the optimal beamforming (BF) vector at the base station (BS) for each user is first obtained using statistical channel state information (CSI). Then, a closed-form expression for the achievable sum rate is derived in terms of a finite number of generalized Meijer-G functions, which is applicable to an arbitrary number of array elements and/or users, and provides an efficient means of evaluating the system performance. Finally, numerical results are provided to confirm the validity of the theoretical analysis and show the impact of various channel parameters on the system performance.

Graphene synthesis by chemical vapor deposition (CVD) on Cu foil involves a series of complex interplays between the atmosphere and Cu substrate. The large number of topographical irregularities and impure elements existing in the normal Cu foils inevitably result in heterogeneous graphene nucleation and uncontrolled growth. Thus, resolving the mutual entanglements between topographical irregularity, impure element, and carbon is fundamental for the understanding of graphene nucleation and growth. Here, two kinds of Cu surface features, topographical Cu hills and elemental oxygen, are deliberately introduced and their interaction is studied. The synergistic effects of Cu hills and oxygen on graphene nucleation and growth are further demonstrated. Molecular dynamics simulations are employed over the whole process to explain the experimental phenomena including Cu hill construction, oxygen distribution, and carbon adsorption. This work is crucial in revealing the microscopic mechanisms for graphene nucleation and growth, and can shed light on how to controll graphene synthesis via Cu surface engineering.

Backscattering-immune propagation is one of the unique characteristics in topological photonic crystals. Such functionality can be realized by constructing a three-dimensional chiral channel in photonic crystals, of which the fabrication process cannot be compatible to complementary metal-oxide-semiconductor lithography. Here, we employed projection microstereolithography to fabricate a three-dimensional chiral channel surrounding in a photonic crystal template with the lattice constant of 462 μm. Both projected band structure and Poynting vector patterns of the three-dimensional chiral channel are numerically calculated. Our work provides a feasible way to fabricate a backscattering-immune waveguide in three-dimensional photonic crystals.

Urolithiasis commonly occurs in kidney and ureteral, and may cause local organ/tissue damage, even kidney failure. The incidence of this disease is increasing worldwide, in which calcium oxalate is the major composition forming the urinary calculus. Therefore, to monitor this disease for the prevention and treatment, measuring the oxalate in the urine is of great significance. Here, a rapid and sensitive colorimetric method was developed based on 3,3',5,5'-tetramethylbenzidine-manganese dioxide (TMB-MnO2) nanosheets for oxalate detection. MnO2 nanosheets acted as an efficient biomimetic oxidase to catalyze the reaction with TMB and oxalate. Pale yellow TMB can be oxidized to blue oxide TMB catalyzed by BSA-stabilized MnO2 nanosheets, and oxalate can selectively inhibit this reaction by consuming and reacting with MnO2 nanosheets, thus achieving the quantitative detection of oxalate. Moreover, a home-made bionic electronic-eye (E-eye) system was developed as a portable in-situ detection platform to efficiently measure the oxalate concentrations in 10 s by direct photographing. By optimizing experimental conditions, this method shows a wide linear range (7.8 μM to 250 μM) and a low detection limit (0.91 μM) for oxalate detection. Besides, this method exhibits high selectivity even with 80-fold interfering chemicals. Furthermore, the performance of the method was validated by testing the artificial urine samples, indicating its great potential for monitoring and diagnosis of urolithiasis in point-of-care applications.

A mixed bacterial community, which is defined as PB-Z in the study, could directly utilize a high concentration of starch and starchy residue to produce hydrogen. The aim of the work was to elucidate the possible mechanism of the single stage system, improve the performance of hydrogen production and COD removal, and evaluate the potential of its engineering application. The result of high-throughput sequencing showed that the consortium PB-Z was mainly composed of photosynthetic bacteria and hydrolytic/acidogenic bacteria. Therefore, starch could be used in a single stage system. Adding both Fe2+ and Ca2+ could significantly increase the maximum hydrogen production rate and cumulative hydrogen production by 168.8% and 70.7% compared with the control group (p

Caprocks play an important role in the trapping of coalbed methane (CBM) reservoirs. To study the sealing capacities of caprocks, five samples with different lithologies of Neogene clayrock, Paleogene redbeds, Permian sandstone, Permian mudstone and Permian siltstone were collected and tested using experimental methods of microstructure observation, pore structure measurement and diffusion properties determination. Results indicate that with denser structures, lower porosities, much more developed micropores/transition pores and higher pore/throat ratios, mudstone and siltstone have the more ideal sealing capacities for CBM preservation when comparing to other kinds of caprocks; the methane diffusion coefficients of mudstone/siltstone are about 6 times higher than sandstone and almost 90 times higher than clayrock/redbeds. To further estimate the CBM escape through caprocks, a one-dimensional CBM diffusion model is derived. Modeling calculation result demonstrates that under the same thickness, the CBM sealing abilities of mudstone/siltstone are almost 100 times higher than those of clayrock/redbeds, and nearly 17 times higher than sandstone, which indicates that the coal seam below caprocks like clayrock, redbeds or sandstone may suffer stronger CBM diffusion effect than that below mudstone or siltstone. Such conclusion is verified by the case study from III3 District, Xutuan Colliery, where the coal seam capped by Paleogene redbeds has a much lower CBM content than that capped by the Permian strata like mudstone, siltstone and sandstone.

Recently, two-dimensional (2D) materials have been applied in organic photovoltaics (OPVs) as electrode modifier or third component in bulk due to their high charge carrier mobility, various electronic band structure, and facile fabrication via liquid phase exfoliation. Herein, solution exfoliated few layers black phosphorus (BP) and tungsten diselenide (WSe2) were used as third component in bulk heterojunction OPVs, resulting in improved power conversion efficiencies (PCEs) from 8.60% for reference device, to 9.20% and 9.24% for devices based on BP and WSe2, respectively. Thorough study has been executed to look into the bulk morphology change and intermolecular charge transfer behavior within the OPV device by means of atomic force microscopy, grazing-incidence small-angle X-ray scattering, photoluminescence spectroscopy, and electrochemical impedance spectroscopy. Results show that a neat BHJ morphology and low energetic loss donor/acceptor (D/A) interfaces were achieved when incorporated with BP nanoflakes or WSe2 nanofalkes, leading to suppressed exciton recombination and enhanced charge transport property. Besides, more balanced bipolar carrier mobility within the bulk also helped boost the performance of OPVs. The storage and operating stabilities of the devices are also improved after incorporating with BPNFs or WSNFs. This work suggests the potential application of 2D materials as third component in OPV applications.

We comprehensively studied the electrical, optical, and mechanical properties, and stability of the hybrid transparent conductive electrode (TCE) prepared by transferring graphene onto random silver nanowires (AgNW) on poly(ethylene terephthalate) (PET) substrates. Compared with the pristine AgNW TCE, the AgNW-graphene hybrid TCE was found to exhibit lower surface roughness, better optical and electrical properties, and excellent long-term stability and flexibility. The power conversion efficiency of the inverted organic solar cells (OSCs) with PTB7:PC71BM as the active material built on the PET/AgNW-graphene TCE is 6.47%, which is 8% higher than the OSCs built on AgNW TCE, and much better than the OSC with conventional ITO. Moreover, the flexible OSCs built on the PET/AgNW-graphene exhibit excellent properties under curved conditions, which suggest that it is promising for applications to uneven surfaces.

Cardiovascular disease remains the leading threat to human life and health, however, a powerful method to mimic the heart in vitro to study the mechanisms of drug therapy on cardiovascular disease is still lacking. In this work, bionic engineered cardiac tissue (ECT) based on a porous scaffold was fabricated, and microelectrode arrays (MEAs) were utilized for extracellular electrophysiological recording. Polylactic acid (PLA) and poly-e-caprolactone (PCL) were used to fabricate the porous scaffold via 3D printing and electrospinning, and then cardiomyocytes from neonatal Sprague Dawley (SD) rats were cultured on the PLA/PCL scaffold to construct the ECT. The strength and biocompatibility of the scaffold were verified via evaluating the cell viability and mechanical beating status. A set of MEA sensors and a home-made detection system were designed, and the ECT was coupled with the MEA sensors for electrophysiological evaluation. The functionality of the ECT was verified via administrating isoprenaline (ISO). This work provides a new approach for evaluating ECT, which is expected to be applied to pharmaceutical studies.

The great challenge in preparing a biomimetic enzyme sensor is to have sensitivity and selectivity equal to or better than its corresponding biological sensor. Porous electrodes possess a large surface area and are often used to greatly improve the sensor sensitivity. However, how to tailor the pore structure, especially the pore size distribution to further improve the sensitivity and selectivity of a biomimetic sensor, has not been investigated yet. The superoxide anion (O2˙−) plays essential roles in various biological processes and is of importance in clinical diagnosis and life science research. It is generally detected by the superoxide dismutase enzyme. Herein, we delicately tailor the pore structure of carbon nanofibers (CNFs) by pyrolysis to obtain an optimal mesopore structure for strong adsorption of DNA, followed by guiding the growth of Mn3(PO4)2 as a biomimetic enzyme toward highly sensitive detection of O2˙−. The Mn3(PO4)2–DNA/CNF sensor achieves the best sensitivity among the reported O2˙− sensors while possessing good selectivity. The enhancement mechanism is also investigated, indicating that the mesopore ratio of CNFs plays an essential role in the high sensitivity and selectivity due to their strong adsorption of DNA for guiding the growth of a large amount of uniform sensing components, Mn3(PO4)2, toward high sensitivity and selectivity. The biomimetic sensor was further used to in situ monitor O2˙− released from human keratinocyte cells and human malignant melanoma cells under drug stimulation, showing high sensitivity to real-time quantitative detection of O2˙−. This work provides a highly sensitive in situ real-time biomimetic O2˙− sensor for applications in biological research and diagnosis, while shedding light on the enhancement mechanism of the pore structure, especially the pore size distribution of a porous electrode for high performance sensing processes.

Drug-induced cardiac side-effects remain a major cause for the removal of drugs from the market and the termination of significant numbers of drug development projects. Many of the physiological and pharmacological reasons are still unclear. In this study, to comprehensively evaluate the cardiac side-effects of drugs, high-temporal-range evaluation with an HL-1-based impedance and long-term electrophysiology recording platform was proposed. Integrated with microscale interdigitated electrodes (IDEs) and planar microelectrodes, the platform could get reliable cell viability monitoring and extracellular electrophysiology recording simultaneously for low system signal drifting and noise (10 μV) in long-term experiments. HL-1 cardiac muscle cells were used as a target cardiac electrophysiology model because they are, by far, the only cardiomyocytes that can continuously divide while maintaining specific characteristics of adult cardiomyocytes. Vinblastine and nifedipine were introduced to verify the performance of this platform in a different time-dependent manner. According to the extracted cell viability and electrophysiological characteristics including cell impedance (namely, cell index, CI), extracellular field potential (EFP), firing rate (FR), inner-period and period-to-period intervals, the results showed that vinblastine exhibited a relatively strong effect on cell viability (maximum 79.83% decrease after 24 hours) and led to the fluctuation of inner-period intervals in long-term monitoring. In contrast, nifedipine presented a negligible effect on cell viability compared to control groups (maintaining minimum 86.20% of viability on an average after 24 hours), but a shortened QT interval (15.2% at least) was observed immediately. In summary, all the two time-dependent drug-induced results indicated that this HL-1-based impedance and long-term electrophysiology recording platform can not only monitor cell viability through the whole experiment but also possess both quick-reaction and long-term tracking ability for identical requirements, thus providing a promising and useful way for drug-induced cardiac side-effect evaluation in a high temporal range.

Satellite communication networks are expected to be indispensable as part of an integrated complement for the upcoming 5G networks since they can provide the most comprehensive coverage and reliable connection for areas where are economically unviable and/or difficult to deploy terrestrial infrastructures. Meanwhile, the power-domain non-orthogonal multiple access (NOMA), which can serve multiple users simultaneously within the same time/frequency block, has been viewed as another promising strategy used in the 5G network to provide high spectral efficiency and resource utilization. In this paper, we introduce a general overview of the application of the NOMA to various satellite architectures for the benefits of meeting the availability, coverage, and efficiency requirements targeted by the 5G. The fundamental and ubiquitous features of satellite link budget are first reviewed. Then, the advantage and benefit of introducing the NOMA scheme in various satellite architectures, such as conventional downlink/uplink satellite networks, cognitive satellite terrestrial networks, and cooperative satellite networks with satellite/terrestrial relays, are provided, along with the motivation and research methodology for each scenario. Finally, this paper reviews the potential directions for future research.

The incorporation of cognitive radio (CR) techniques into satellite communication systems, has been considered as one of the most promising approaches to address the spectrum scarcity, which constitutes an advanced infrastructure known as cognitive satellite terrestrial network (CSTN). Due to the estimation error or feedback delay, perfect channel state information (CSI) of satellite and/or terrestrial links in CSTNs are normally unavailable. This paper investigates the effect of imperfect CSI on the performance of CSTN, where a secondary satellite network coexists with a primary terrestrial network by employing the underlay cognitive mechanism according to which the satellite user is allowed to access the licensed spectrum without deteriorating the operation of terrestrial user. Specifically, we derive the analytical expressions for the outage probability and ergodic capacity of the cognitive network, which provides an efficient approach to jointly evaluate the impacts of imperfect channel estimations for different links on the performance of considered network. Moreover, simple asymptotic outage probability formula in the high signal-to-noise ratio regime is presented to reveal the diversity order and coding gain of the CSTNs. Finally, numerical results are provided to confirm the validity of the theoretical analysis, as well as quantitatively analyze the effects of various system parameters on the performance of the CSTNs with CSI imperfection.

The inherent broadcast nature has exposed the land mobile satellite (LMS) communication systems to severe security threats in both the civil and military applications. This paper investigates the secrecy performance of a Shadowed-Rician fading multi-antenna LMS communication system with imperfect channel estimation, which consists of a satellite, a legitimate receiver and a cluster of unauthorized eavesdroppers who want to overhear the confidential message. Specifically, the analytical expressions for the probability of non-zero secrecy capacity are derived in terms of the Meijer-G functions, which provide an efficient means to evaluate the secrecy performance of the system. Then, both the exact and asymptotic secrecy outage probability expressions of the considered system are obtained. Furthermore, based on the simple asymptotic secrecy outage probability, we can reveal two key performance metrics, namely, the secrecy diversity order and secrecy array gain. Finally, simulation results are carried out to validate the theoretical results and show the superiority of employing multiple antennae in enhancing the secrecy performance for LMS communication systems. Our findings suggest that the secrecy diversity order only depends on the number of antennas at the legitimate receiver, and is independent of the imperfect channel estimation and the shadowing severities of both the main and eavesdropper channels.

An automated and sensitive method based on in-cell clean-up pressurized liquid extraction (PLE) was developed and validated for the simultaneous determination of 14 brominated diphenyl ethers in sewage sludge samples. Extraction and online clean-up were integrated into one step using PLE with in-cell clean-up (3 g acidic silica and 4 g florisil). The effects of various operational parameters on the performance of extraction and online clean-up procedures were carefully investigated, and optimum results were obtained when the conditions were fixed at 100 °C, 1500 psi, and two extraction cycles with a heating time of 5 min using hexane/dichloromethane (50 : 50, v/v) as extraction solvents. Separation and quantification of target compounds were carried out by gas chromatography-mass spectrometry with negative chemical ionization (GC-NCI-MS). The in-cell PLE method was evaluated by repeated analysis of target compounds from spiked sewage sludge and excellent recoveries (85–105%) were observed for most analytes at each spiking level, with the RSD values being generally below 15%. Finally, the method was applied to the analysis of real sewage sludge samples from wastewater treatment plants located in Shanghai (China), where the dominant brominated diphenyl ether was BDE-209, with concentration levels between 54.86 and 215.10 ng g−1 dry weight.

Real-time dynamic vascular network imaging can provide accurate hemodynamic and anatomical information, facilitating the diagnosis of blood circulatory system-related diseases and achieving precise evaluation of therapeutic effects. In vivo luminescence imaging in the NIR-IIb biological window (1500-1700 nm) has developed into a next generation of optical imaging method with significantly improved temporal-spatial resolution and penetration depth. Unfortunately, an imaging contrast agent capable of emitting NIR-IIb luminescence with sufficient brightness in this region is lacking. Herein, we designed and proposed a type of dye-sensitized rare earth-doped nanoparticle (RENPs@Alk-pi) with obviously boosted NIR-IIb emission and high biocompatibility, which can be used to realize the real-time NIR-IIb luminescence imaging with high temporal-spatial resolution and contrast. The dye sensitization process provides a 40-fold enhanced brightness of the NIR-IIb emission at 1525 nm of Er3+. Consequently, the RENPs@Alk-pi was not only able to depict a vascular network but also applicable in noninvasively monitoring the dynamic vascular processes and changes in the vascular anatomy of two blood circulatory system-related disorders, including hindlimbs ischemia and atherosclerosis. Our research provides a powerful tool for evaluating vascular network-related dysfunction and physiological processes.

This article investigates the secure energy efficiency (EE) optimization problem in a cognitive satellite-terrestrial network with a capable eavesdropper. The objective is to maximize the secure EE for the primary satellite network while satisfying the allowable signal-to-interference-plus-noise ratio requirements of the secondary and primary users along within the transmit power limitation of both satellite and the terrestrial base station. Owing to the nonconvexity and intractability of the original optimization problem, a beamforming scheme and associated transformation algorithms are proposed by jointly applying the Taylor approximation, fraction programming, and alternating search to cope with the implementation difficulty. The key is to convert the original optimization problem into a simple convex framework and obtain the optimal solution step by step. Finally, numerical simulations are given to verify the feasibility and practicability of the proposed optimization algorithms.

With the continuous improvement of China's railway construction level, the requirements for the quality of train operation are also improved. For the mixed passenger and freight railway, it is necessary to transit from the simple design concept of safety to the design concept of the unity of comfort and safety. Therefore, modern numerical calculation method or simulation software method is used to replace the traditional quasi-static calculation method, and SIMPACK, ABAQUS and other related software are mainly used to analyze the operation quality and track structure dynamics of the line design scheme. The derailment coefficient, vertical acceleration and other evaluation indexes are used to evaluate the safety and comfort of the line, and the dynamic analysis of the track structure is carried out based on the vertical force. The research shows that under the condition of this line, when the passenger and freight train run at the designed speed per hour in the curve section, they can meet the specification requirements of various indexes, and there is still room for increasing speed, and the stress and strain value of the track structure can meet the specification requirements.

Whether intentionally or unintentionally, waterflooding always takes place under fracturing condition in tight reservoir because of the extremely limited water absorption ability of the formation. Recently, we proposed a novel workflow, including real-time monitoring, formation testing analysis, and dynamic production analysis, to timely and effectively identify the initiation of waterflood-induced fractures (WIFs) and characterize the waterflooding behaviors for a well group. In this paper, we further provide a supplementary study to evaluate the waterflooding performance from the well group to the field basis. The utilization factor (UF) is first estimated on the basis of injection/production data by material balance theory, which provides an overall picture of water injection efficiency every year. Then, the areal (straightforwardly showed by water cut and formation pressure distributions) and vertical sweep (includes the water absorption in injectors and water breakthrough in producers) behaviors are studied to investigate the waterflooding characteristics and residual oil distributions. Lastly, three key influence factors are detailedly discussed: sand body connectivity, WIFs, and injection and production correspondence. Combining the previous work for the single well group, and the study in this paper to field basis, one can have a better and much more comprehensive understanding of the waterflooding performance and then thus take the corresponding adjustment measurements to improve waterflooding effectiveness.

Fake news detection is a challenging problem due to its tremendous real-world political and social impacts. Previous works judged the authenticity of news mainly based on the content of a single news, which is generally not effective because the fake news is often written to mislead users by mimicking the true news. This paper innovatively utilizes the connection between multiple news, such as their relevance in time, content, topic and source, to detect fake news. We construct a heterogeneous graph with different types of nodes and edges, which is named as News Detection Graph (NDG), to integrate various information of multiple news. In order to learn deep representation of news nodes, we propose a Heterogenous Deep Convolutional Network (HDGCN) which utilizes a wider receptive field, a neighbor sampling strategy and a hierarchical attention mechanism. Extensive experiments carried on two real-world datasets demonstrated the effectiveness of our work in solving the fake news detection problem.

In this work, we report a successful extension of the family of light-emitting colloidal carbon nanostructures to a number of different shapes and morphologies, namely, carbon nanorolls (CNRs) and carbon nanobelts (CNBs). Near infrared (NIR)-emissive CNRs were synthesized via a solvothermal fusion of carbon dots (CDs) triggered by a dehydration process of their surface functional groups. They appear in a form of short cylinders, with diameters ranging from 20 to 40 nm and cylinder lengths ranging from 7 to 20 nm. In ethanol solution, CNRs have a maximum absorption peak at 665 nm and a NIR emission band extending from 650 to 800 nm, with a photoluminescence quantum yield of 9.2%. Intriguingly, the rolled structure of CNRs can be uncoiled under 655 nm laser irradiation (power density 1 W·cm-2) of their solution in ethanol, forming CNBs with a width of 7-20 nm and lengths reaching several hundreds of nanometers, which is accompanied by a considerably decreased absorption band at 665 nm and a decreased NIR emission. This unfolding is ascribed to the decrease of the strength of interlayer hydrogen bonding, owing to the photothermally induced dehydration and further carbonization of the CNRs. Alongside the decreased NIR emission, CNBs exhibit enhanced green and red emissions under UV and green light excitation, respectively, which allows us to demonstrate multiple-level luminescence encryptions on a paper stamped with CNR- and CNB-inks.

Paddy soils in southern China are heavily co-polluted by arsenic (As) and cadmium (Cd). The accumulation of these contaminants in rice grains may pose a high health risk. We evaluated the impact of adjusted water management practice (i.e., conventional irrigation and aerobic treatment after heading stage) and the application of two immobilization agents (i.e., CaO and Fe2O3) on the accumulation of As and Cd in rice grains of three rice varieties (i.e., Jinyou-463, Jinyou-268, and Mabayouzhan). The different schemes were tested via conducting a field experiment in paddy soil in Shaoguan, Guangdong Province, China. The results showed that the combined scheme (selecting Jinyou-268, aerobic water management after the heading stage, and 0.09% CaO and 0.5% Fe2O3 amendments) exhibited the best performance in the reduction of As and Cd accumulation in rice grains. This combined scheme decreased the grain As concentration by 26.19% and maintained the Cd at a low level (0.056 mg/kg) as compared to the use of local conventional irrigation patterns. Moreover, health risk assessment demonstrated that by applying the optimal scheme, neither As nor Cd content in rice had carcinogenic risk. However, the grain As remains at a high non-carcinogenic risk. We suggest that future field study design should fully incorporate the uncertainty of the natural environment to make the research conclusions more feasible for popularization and utilization. This study demonstrated an approach of utilizing the synergy effects of various measures for safe rice production in fields subjected to As and Cd contaminations.

Broad Learning System (BLS) is a latest proposed flat network, which has an effective and efficient learning capability. Due to excellent performance, BLS has been applied to many fields. However, there is little attention on the structure simplification of BLS network. In this paper, drawing lessons from application of Least Angle Regression (LARS) in feature selection, we propose Least Angle Regression Adaptive Incremental Broad Learning System (LARS-BLS). Begin with a network with complex structure, LARS-BLS firstly ranks all nodes, then, the nodes are added to the empty network in turn according to the contribution rate from high to low. Then, the adaptive coefficient is calculated according to the accuracy change rate of the model to adjust the number of nodes added to the model accordingly. When the modeling requirements are met, stop adding nodes. Finally, a sparse BLS model without redundant nodes is constructed. The proposed method is applied to a real-world application and some common data sets. The results show that our proposed algorithm is effective and efficient.