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The replacement of small cations with bulkier organic cations containing long alkyl chains or benzene rings to form a thin two-dimensional (2D) perovskite passivation layer on three-dimensional (3D) perovskite (2D/3D) has become a promising strategy for improving both the efficiency and stability of perovskite solar cells (PSCs). The 2D layer defines the interfacial chemistry and physics at the 2D/3D bilayer and endows the 2D/3D structure with better chemical and thermal stability. Herein, 2D/3D (CF3-PEA)2FA0.85MA0.15Pb2I7/FA0.85MA0.15PbI3 planar heterojunction perovskite was produced using a facile interfacial ion exchange process. The 2D (CF3-PEA)2FA0.85MA0.15Pb2I7 capping layer can not only passivate the FA0.85MA0.15PbI3 film but also act as super-hydrophobic layer to inhibit water diffusion and significantly enhance the stability. The 2D capping layer can also establish a unique graded band structure at the perovskite/Spiro-OMeTAD interface and lead to p-type doping for Spiro-OMeTAD layer which is beneficial for efficient charge transport. Optimized PSCs based on this 2D/3D heterojunction yield a champion power conversion efficiency (PCE) of 23.1% and improved stability. The device maintains 84% output for 2400 h aging under ambient environmental conditions without encapsulation, and maintains 81% for 200 h under illumination with encapsulation. This work will inspire the design of more fluorinated 2D perovskite interfaces for advanced photovoltaics and beyond.

The eigenvalues of the sample covariance matrix can capture signal correlations and noise characteristics well, which are widely used for spectrum sensing in cognitive radio networks. Some totally blind spectrum sensing algorithms were proposed, such as maximum eigenvalue-to-arithmetic mean (ME–AM), maximum eigenvalue-to-geometric mean (ME–GM), and arithmetic-to-geometric mean of eigenvalues (AGM) methods. This article makes full use of the advantages of these algorithms and proposes a universal spectrum sensing algorithm based on maximum eigenvalue, arithmetic mean, and geometric mean of eigenvalues. The proposed algorithm takes the weighted geometric mean of the test statistics of the ME–AM and AGM algorithms as new test statistic and includes the ME–AM, ME–GM, and AGM algorithms as special cases. Following the random matrix theory framework, in a similar vein to the ME–AM and ME–GM algorithms, we derive the analytical expressions of false alarm probability, threshold, and detection probability of the proposed method using the Tracy–Widom distribution of maximum eigenvalue. In addition, we discuss the problem of designing the optimal weighting factor through theoretical analysis and simulation experiments. Finally, simulation results verify that the universal algorithm can effectively improve the detection performance.

A novel green composite flame retardant, bismuth oxychloride nanosheet decorated with chitosan and phytic acid (BiOCl@CS-PA) was prepared in order to improve the fire safety of flexible poly(vinyl chloride) (PVC). Introducing phytic acid (PA) is aimed at promoting the flame retardancy of BiOCl nanosheets in condensed phase using the synergistic effects. Chitosan (CS) not only acts as a bridge between BiOCl and PA, but also increases residue as a charring agent. Adequate characterizations verified that the BiOCl@CS-PA has been prepared successfully. When 3 wt.% of BiOCl@CS-PA was imparted into the PVC matrix, the resultant PVC composite can pass V-0 rating in the UL-94 test. Additionally, cone calorimetry test demonstrated that 3 wt.% of BiOCl@CS-PA reduced the first peak heat release rate and inhibited the pronounced peak heat release rate of PVC matrix between 300–400 s in comparison with the BiOCl nanosheets, indicating a further improvement in flame retardancy of PVC/BiOCl@CS-PA composite with the help of PA in the condensed phase. Microstructure and morphology of the char residue of PVC/BiOCl@CS-PA were analyzed to reveal the flame retardant mechanism. The results indicated that the joint action of PA and CS improves the quality of the char layer, which contributes to improving the flame retardancy in condensed-phase.

Lakes at a global level have increasingly experienced algal blooms in recent decades, and it has become a key challenge facing the aquatic ecological environment. Remote sensing technology is consi...

In this letter, a cascade algorithm combined subband decomposition with an eigenvalue-based detection scheme is proposed to detect moving targets in sea clutter for the radar system with short pulses. Using a discrete Fourier transform-modulated filter bank, on the one hand, subband decomposition can effectively suppress clutter as well as increase the coherent integration time. On the other hand, it transforms the scene where the target spectrum is separated from the clutter spectrum into the scene where the target spectrum overlaps with the clutter spectrum. In the target subband, the noncoherent method using amplitude difference is more favorable for detection due to the nonobvious phase difference caused by the overlap of the target spectrum and the clutter spectrum. Considering that the maximum eigenvalue can reflect the signal intensity and capture the signal correlations well, the maximum eigenvalue of the covariance matrix is adopted to discriminate the target from the clutter. Finally, the simulation results show that the proposed algorithm achieves superior performance.

The main purpose of this paper is to study the effect of propylene glycol alginate sodium sulfite nanoparticles on myocardial injury in diabetic rats through Sirt1/HIF-1 α signal pathway. The effects of different doses of propylene glycol alginate sodium sulfite nanoparticles on the content of malondialdehyde, creatine kinase, nitric oxide, the activity of superoxide dismutase, lactate dehydrogenase and nitric oxide synthetase in the myocardial tissue of diabetic rats observed. The function indexes of HIF-1 α mitochondria and measured the expression of Sirt1/HIF-1 α pathway. The results show that compare with the diabetic model group, the blood glucose level of the rats in the propylene glycol alginate sodium sulfite nanoparticles treatment group was slightly low. The serum LDH, CK and MDA contents were significantly low, and the activity of SOD in the myocardium in the propylene glycol alginate sodium sulfite nanoparticles treatment group was significantly higher than that in the diabetic model group in the treatment group. The activity of NOS and the content of MDA and no were lower than that in the diabetic rats, the expression of Sirt1 and HIF-1α in myocardial tissue was increased. It suggested that propylene glycol alginate sodium sulfite nanoparticles alleviate myocardial damage in diabetic rats by regulating Sirt1/HIF-1α signal pathway, improving mitochondrial function and inhibiting oxidative stress.

Fast time-varying channel parameters and large penetration losses for signals passing through train carriages are two well-known challenges for wireless communications on high speed rails (HSRs). In this paper, we introduce, for the first time, backscatter technology into HSR wireless communications, which can address these two challenges and yet have low complexity of signal processing and low cost of circuit implementation compared with traditional solutions such as relaying or beamforming. Specifically, we propose a backscatter aided wireless transmission (BAWT) scheme and demonstrate that it outperforms the existing direct wireless transmission (DWT) scheme. We derive the upper and lower bounds of channel capacity for BAWT and prove that it exceeds that of DWT on certain conditions. We also propose the transceiver design for both BAWT and DWT, including joint carrier frequency offset and channel estimator, and signal detector. We show that BAWT, rather than DWT, can obtain the channel statistical information in practical applications due to fixed train antennas and unchanged tracks, which can be utilized to facilitate channel estimation. Finally, simulation results are provided to corroborate the proposed solutions.

The existing Goodness of fit (GoF) test based spectrum sensing algorithms mostly use samples or energies as observations to make decisions, which can hardly achieve satisfactory performance especially when the Primary user (PU) signals are highly correlated. Meanwhile, the eigenvalue of covariance matrix can reflect signal correlations well. Motivated by this, we study the distribution of eigenvalue and propose an eigenvalue based GoF spectrum sensing algorithm. In the proposed scheme, we use the ratios of maximum to minimum eigenvalue as observations and thus it can bring performance improvements through capturing correlation of PU signals. We also provide the related theoretical analysis for the proposed method. Simulation results show that the proposed method overcomes the problem of noise uncertainty and achieves performance improvement over the classical samples-based GoF test.

In order to enhance the flame retardancy of intumescent flame retardant (IFR) in polypropylene (PP) using synergistic effects, a three-dimensional flower-like nickel cobaltate (NiCo2O4) was prepared and first introduced into the PP/IFR composite. The combustion behavior, thermal stability, mechanical properties and hydrophobicity of PP/IFR containing NiCo2O4 are studied in detail. When the contents of NiCo2O4 and IFR are 1.5 wt% and 18.5 wt%, respectively, the limit oxygen index value of the PP composite reaches 34.5 and passes the UL-94V-0 level. The cone calorimetry test also reveals that NiCo2O4 plays an excellent synergistic role with IFR, resulting in a significant improvement in the flame retardancy of the PP composite. Compared with pure PP, the presence of 1.5 wt% of NiCo2O4 delays combustion, decreases the peak heat release rate and total heat release by 64% and 40%, respectively, as well as exhibits a significant smoke suppression effect. At high temperature, the residual char of the PP composite is increased, and the degree of graphitization of corresponding char is also improved, both of which contribute to forming a continuous dense stable char layer and acquire a better shielding effect. The presence of NiCo2O4 only has a slight negative effect on the tensile strength of the PP composite. Interestingly, the hydrophobicity of the PP composite at this ratio is improved to some extent compared with that of the composite containing only 20 wt% IFR; thus, the synergistic flame-retardant effect is also ensured in the water resistance test within a certain time.

Background Variable message signs (VMS) have been widely applied to alleviate traffic congestion by providing spatiotemporal information related to traffic and network conditions to drivers. There is a debate on whether the VMS information would lead to the less-alleviation of congestion or congestion transfer to the adjacent roads in the different traffic congestion situations due to the inappropriate VMS information. Additionally, it is still unknown how to find a practically applicable method to design the most effective VMS information for drivers. Objective In order to design and display the appropriate VMS information for drivers under different traffic conditions, this paper aims to identify the effects of VMS on individuals’ route choice behavior by exploring the different effects of VMS on the several separate groups. Drivers in these groups are homogenous in gender, driving experience, education level, occupation, and monthly income. Methods In the hypothetical scenario, a stated preference (SP) questionnaire was conducted to build the dataset consisting of 3462 samples from local private and taxi drivers. The decision tree via the chi-squared automatic interactive detector (CHAID) algorithm is utilized to split drivers into several groups, and further two fixed-parameter logistic regression models considering intra-heterogeneity between drivers (i.e., considering and not considering systematic taste variations), and random-parameter logistic regression models are employed to analyze the factors affecting driver route choice behavior of each group. Results Five groups with different driver characteristics are identified. Besides, the modeling results indicate that the effect of the VMS information on individual route choice behavior is heterogeneous. These findings include: (i) random-parameter logistic regression models have a significantly improved goodness-of-fit because of the lower AIC and BIC; (ii) compared with the stated cause information on road construction and congestion, the accident information had a larger effect on driver route choice behaviors; (iii) the route choice behaviors of drivers with more than 6-year driving experience are affected by the VMS information on road constructions, accidents, and the quantitative delay time; (V) the route choice behaviors of less-experienced female drivers were affected by display formats and display frequencies of VMS information. Conclusions The findings from this study can assist traffic authorities in designing the most appropriate VMS for different traffic congestions based on driver characteristic distribution and the road capacity for improving the practicability of VMS information and further provide the theoretical evidence for the design of in-vehicle personalized information service systems.

This letter considers integrating a backscatter link with a reconfigurable intelligent surface to enhance backscatter communication while assisting the direct communication. We derive the probability that the backscatter channel dominates in the composite channel. This probability is a useful performance measure to determine the number of reflectors. Since the exact probability lacks a closed-form solution, we develop two approximations by modeling the gain of the backscatter link with a Gaussian or Gamma distribution. We found that these approximations match well with the exact value. Importantly, with a well-designed number of reflectors, the channel gain of the backscatter link may be always stronger than that of the direct one.

Channel estimation is a well-known challenge for wireless orthogonal frequency division multiplexing (OFDM) communication systems with massive antennas on high speed rails (HSRs). This paper investigates this problem and design two practicable uplink and downlink channel estimators for orthogonal frequency division multiplexing (OFDM) communication systems with massive antenna arrays at base station on HSRs. Specifically, we first use pilots to estimate the initial angle of arrival (AoA) and channel gain information of each uplink path through discrete Fourier transform (DFT), and then refine the estimates via the angle rotation technique and suggested pilot design. Based on the uplink angel estimation, we design a new downlink channel estimator for frequency division duplexing (FDD) systems. Additionally, we derive the Cramer-Rao lower bounds (CRLBs) of the AoA and channel gain estimates. Finally, numerical results are provided to corroborate our proposed studies.

A parameterized controller design approach is proposed to solve the problem of multi-objective control for vehicle active suspension systems by using symbolic computation. The considered model is a quarter-vehicle model of the active suspension system. The multi-objective robust control performances include the sprung mass acceleration, suspension deflection, and tire deflection. Based on dissipative Hamiltonian systems and Lyapunov function, a multi-objective $H_{\infty }$ controller design approach is developed, which can avoid solving Hamilton-Jacobi-Issacs equations. Then, an algorithm of solving semi-positive definite polynomial with tuning parameters is proposed by using symbolic computation. Furthermore, a method of parameter optimization is proposed. Simulations and comparation show that the control performance is significantly improved comparing with passive controlled systems and existing other control systems for active suspension systems.

The deep learning methods in the field of computer vision and big data are becoming more and more mature. Through the application of big data and deep learning technology, the diagnosis of artificial intelligence medical image can be realized, which provides a new opportunity for the automatic analysis of obstetrics medical image and the assistance of doctors to realize high-precision intelligent diagnosis of diseases. The current medical obstetric image diagnosis platform mainly targets low-resolution medical obstetric image files, and does not consider the data-sharing problem of the distributed file system in different storage nodes, which greatly reduces the efficiency of obstetric image storage and diagnosis. Based on this, this article designs an obstetric image diagnostic platform based on cloud computing technology. First, a medical imaging platform was designed by combining cloud computing technology, caching technology, and a distributed file system. Secondly, the use of contrast-enhanced ultrasound technology provides a more accurate ultrasound image for assessing the structure, size, location, and developmental abnormalities of the placenta. Finally, the effectiveness of the obstetric imaging diagnostic platform proposed in this paper is verified by experiments. The results show that the platform has fast data processing speed and convenient use, which greatly reduces the cost of medical equipment and improves efficiency. The hospital only needs to collect the obstetric image of the patient at the front end, transfer it to the cloud for image processing, and finally diagnose the disease.

This paper considers the problem of spectrum sensing in multi-antenna cognitive radio networks. Energy detection (ED) method for spectrum sensing does not require any information of the source signal and channel, as well as it is suitable for detecting independent identically distributed signals. Since covariance matrix catches the signal correlations well, the maximum eigenvalue detection (MED) method is more competitive than the ED method for correlated signals. Under the framework of random matrix theory, this paper firstly proposes two enhanced detection algorithms based on the maximum eigenvalue and energy of the signal to achieve performance improvement while preserving the advantages of the two algorithms. The proposed algorithms are a generalization of the ED and MED methods. To render the proposed algorithms more practical, we propose two other new blind spectrum sensing algorithms based on the maximum likelihood estimate of unknown noise variance. Using random matrix theory, the theoretical analysis on detection probability, false alarm probability and threshold are given. Finally, simulation results show the effectiveness and robustness of the proposed algorithms.

The estimation of mean matrix for a set of Hermitian positive definite (HPD) matrices can be considered based on a geometric framework. This kind of estimator is closely related to geometric measures, which can be established to measure the dissimilarity between two matrices on the matrix manifold. In this paper, the matrix spectral norm is exploited to derive a new geometric measure on the matrix manifold consisting of all HPD matrices. Correspondingly, the mean matrix associated with the new geometric measure on the matrix manifold is considered via two effective solution techniques. More specifically, the first method transforms the mean matrix estimation into a semidefinite programming problem solved by the interior point method; the second method exploits joint approximate diagonalization to diagonalize the given covariance matrices and then recasts the mean matrix estimation into an optimization problem with linear inequality constraints. Furthermore, two matrix detectors employing the proposed mean matrix estimators are designed for target detection using pulse Doppler radar with a small bunch of pulses. At the analysis stage, we show that the proposed matrix detector can guarantee the bounded constant false alarm rate property in terms of the clutter covariance matrix. Finally, numerical experiments based on simulated clutter data and real sea clutter data are performed to verify the effectiveness and robustness of the proposed matrix detectors.

We investigate the dynamics of kicked pseudo-spin-1/2 Bose-Einstein condensates (BECs) with spin-orbit coupling (SOC) in a tightly confined toroidal trap. The system exhibits different dynamical behaviors depending on the competition among SOC, kick strength, kick period and interatomic interaction. For weak kick strength, with the increase of SOC the density profiles of two components evolve from overlapped symmetric distributions into staggered antisymmetric distributions, and the evolution of energy experiences a transition from quasiperiodic motion to modulated quantum beating. For large kick strength, when the SOC strength increases, the overlapped symmetric density distributions become staggered irregular patterns, and the energy evolution undergoes a transition from quasiperiodic motion to dynamical localization. Furthermore, in the case of weak SOC, the increase of kick period leads to a transition of the system from quantum beating to Rabi oscillation, while for the case of strong SOC the system demonstrates complex quasiperiodic motion., 3 pages, 3 figures

The improvement of color similarity between stereo images can bring better performance to stereo matching algorithms. For this purpose, we present a color correction method to alleviate the color discrepancy between a pair of stereo images, so that the color appearance of one image, i.e., the target image, is consistent with the other image, i.e., the source image. Our method starts with decomposing both the target image and the source image into two intrinsic layers, i.e., the reflectance layer and the shading layer, using intrinsic decomposition. The purpose of intrinsic decomposition is to distinguish and then process different color discrepancies caused by different factors (shading and reflectance) separately and appropriately. Then, a practical and effective consistent segmentation algorithm, which applied to the original stereo images, is proposed to establish the region correspondences. Next, luminance correction method and color correction method, based on the local region correspondences, are adopted to correct the shading layer and the reflectance layer in the target image, respectively, making them as similar as possible to those of the source image. Eventually, the two corrected layers of the target image are combined to yield the final corrected image. The experimental results demonstrate that the proposed method, which using intrinsic decomposition to handle color discrepancy caused by different factors, not only enhances the visual color similarity between the stereo images but also improves the accuracy of their stereo matching.

Matrix constant false alarm rate (M-CFAR) detector based on information geometry provides a novel scheme to the detection of target in sea clutter environment for pulse Doppler radar with small bunch of pulses. The detection performance of the existing M-CFAR detectors is greatly influenced by the geometric measures on the matrix manifold. Different geometrical measures lead to different detection performance, some of which are not satisfactory. Motivated by this, the authors utilise Root-Euclidean, Power-Euclidean, Cholesky-Euclidean and new Riemannian measure to design several kinds of detection schemes, which improve the detection performance. Finally, simulation results verify that the designed detectors achieve a better detection performance with a relatively lower computational complexity.

The bulk defects in the electron transport layers (ETLs) and the interface defects between the ETLs and the perovskite film are detrimental for charge transfer and transport from the perovskite film to the ETLs, which degrade the performance of the planar heterojunction perovskite solar cells (PSCs). Here, low temperature plasma technique with a few types of atmospheres including representative oxidation, reduction, and inert gases is proposed to modify the bulk and surface defects of TiO2 films. TiO2 film treated by CO2 plasma demonstrates a more low-density of defect state in both of surface and bulk than the as-fabricated one. Consequently, the efficiency of PSC is significantly improved from 16.47% of the PSC with the as-fabricated ETL to 18.10% of the PSC with the treated ETL. However, the He and H2 plasma treatments cause the increase in the oxygen-related defects on the surface of TiO2 film or/and in the TiO2 bulk. As a result, the He and H2 plasma-treated ETLs-based PSCs exhibit poor performance. This study highlights that, to tailor metal oxide ETLs for highly efficient PSCs, the plasma technique by the PECVD approach with suitable gas source should be well considered.

To evaluate the chemical decomposition of the perovskite layer caused by the amount of hydroxyl groups remained on the interface of ZnO/perovskite films, ZnO films with different amount of hydroxyl groups are prepared by magnetron sputtering and spin-coating methods. The sputtered ZnO film contains the negligible hydroxyl groups because the hydrogen-free working gases of argon and oxygen are introduced during the sputtering process. In case of the optimized deposition condition under Ar/O2 ratio of 1:4, the sputtered ZnO film shows larger grain size, bigger water contact angle, higher energy-level matching, better optical transmission, and higher conductivity in comparison with the spin-coated ZnO film. Moreover, the planar perovskite solar cells (PSCs) based on the sputtered ZnO electron transport layers (ETLs) yields an optimal power conversion efficiency of 17.22%, sharply outperforming that based on the spin-coated ZnO ETL (14.24%). More notably, the thermochemical stability of the device based on the sputtered ZnO ETL was also significantly improved.

For the pulse Doppler radar system with short pulse sequence, maximum eigenvalue-based matrix CFAR detector (MEMD) provides an effective solution to the problem of detecting moving targets in the background of K distribution sea clutter when the target Doppler frequency is within clutter spectrum. However, its performance is inferior to adaptive normalized matched filter method (ANMF) when the target Doppler frequency heavily deviates from the clutter spectrum. In essence, the reason for the better performance of ANMF method is the clutter is effectively suppressed by whitening and matched filter. Motivated by this, the fusion idea of eigenvalue detection and pre-processing via fast Fourier transform is considered taking advantage of the priori information of target steering vector. A pre-processing-based maximum eigenvalue matrix CFAR detection (P-MEMD) method is proposed to suppress the influence of clutter on detection performance. Finally, the numerical experimental results based on simulated data and real sea clutter data show that the proposed method achieves better detection performance and robustness than some conventional methods.

In this work, three dendrimers with different peripheral functional groups were successfully prepared through a powerful “click chemistry” reaction. Thanks to their spherical topological structure, the NLO performance is superior to that of the corresponding conical dendrimers. Among them, Janus dendrimer J1 with phenyl and pentafluorophenyl groups at the periphery demonstrated the highest NLO effect of 118.0 pm V−1. Also, thanks to the Ar–ArF self-assembly effect, its optical transparency and thermal stability were also improved, with degradation temperatures higher than 260 °C.

Color constancy refers to the ability to make the color of an object not change with the change of the light color of the scene. The use of convolutional neural networks improves the accuracy and stability of color constancy. But the traditional convolutional neural network structure cannot apply the semantic features in the image to the color constancy, which makes the illumination estimation fuzzy, greatly reduces the quality of network training. In order to solve this problem, in this work we propose a new network structure called multi-path feature fusion weighted fully convolutional neural network structure. The network structure contains three convolutional neural network branches for fully extracting semantic features in images. After that, the extracted features are fused and weighted to accurately estimate the light source. Experimental results show that the multi-path feature fusion weighted network structure can make fully use of the semantic feature information in the image to accurately estimate the scene light source. At the same time, it is a more lightweight network, which achieves the simultaneous improvement of the accuracy and speed of light source estimation, meets the requirements of mobile devices for lightweight network models.

Fast time-varying channel parameters and large penetration loss for signals passing through train carriages are two well-known challenges for wireless communications on high speed rails (HSRs). In this paper we introduce, for the first time, backscatter technology into wireless communication systems on HSRs which can address the two challenges and meanwhile have low complexity of signal processing and low cost of circuit implementation compared with traditional solutions such as relay or beamforming technology. Specifically, we propose a backscatter aided wireless transmission (BAWT) scheme and compare its performance with existing direct wireless transmission (DWT) scheme. We also propose the transceiver design for both BAWT and DWT, including joint carrier frequency offset (CFO) and channel estimator, and signal detector. We show that BAWT, instead of DWT, can obtain the channel statistical information in practical applications due to fixed train antennas and unchanged tracks, which can be utilized to facilitate channel estimation. Finally simulation results are provided to corroborate the proposed studies.

KD (K-dimension) tree is widely used in solving multi-dimensional space search problems, such as the nearest neighbor search, ray tracing, etc. During the process of KD tree construction, the median point in a specified dimension is generally chosen as the split point so as to build a balanced tree. As the performance of building a KD tree is strongly influenced by the efficiency of the selection of the median point, a variety of methods have been developed to select the median point quickly and accurately. However, the performance of methods introduced in most previous literature is either uncertain or time consuming. This paper proposes an improved method to build the KD tree based on presorted results. Compared with previous similar work, the new algorithm not only reduces unnecessary comparisons during presorting and construction, but also could handle problems with duplicate data, which expands the application of such methods.

Signal processing on graphs offers a potential framework for signal features extraction by transforming the received signal into graph. Graph based information representation framework is explored and applied to radar target detection problem. The existing algorithm using graphs considers the case of long pulses and needs to perform eigenvalue decomposition, which requires high implementation complexity in practical scenarios. To render this algorithm practical, for the case of short pulses, this paper continues to explore the framework of signal processing on graphs, and designs an enhanced detection algorithm by using the ratio of maximum and minimum connectivity of graphs among the cell under test and reference cells as test statistic. Simulation results show that the proposed algorithm with a low computational complexity achieves superior detection performance than the existing algorithm based on graphs.

In this paper we introduce backscatter technology into wireless communication systems on high speed rails (HSRs). Specifically, we propose a backscatter aided wireless transmission (BAWT) scheme and demonstrate its outperformance over the existing direct wireless transmission (DWT) scheme. We derive the upper and lower bounds of channel capacity for BAWT and prove that the channel capacity for BAWT is larger than that of DWT on certain conditions. Finally, simulation results are provided to corroborate the proposed studies.

Grid remapping is an important mechanism for data transfer between different grids in the Earth modeling system, and searching for relevant points is one of the most complex and time-consuming operations. At present, there are few efficient and robust searching algorithms for unstructured grids. However, with the rise of unstructured grid based model and the improvement of model resolution, providing an efficient search algorithm for unstructured grid is in urgent need in engineering practice. In order to improve the performance of searching process between unstructured grid and other grids when remapping, this paper implements two search algorithms based on KD (K-dimension) tree (the nearest neighbor search and range search). Compared with the performance of brute force search, it is found that the efficiency of search algorithms based on KD tree are much higher than that of brute force search, including the nearest neighbor search and range search. The experimental results provide practical experience for the development of remapping software in the future.

A robust structural control method is proposed to solve the problems of structured uncertainties and multi-objective control for vehicle active suspension systems. The considered model is a quarter model of vehicle subject to unknown ground disturbance and structured uncertainties. The proposed method is based on robust structured control well supported by singular value decomposition (SVD) method, yielding a multi-objective control design approach, applicable to almost any active suspension systems. Some experiments show that the control performance of robust structural control for vehicle active suspension systems with structured uncertainties is significantly improved comparing with passive controlled system and existing other controlled active suspension systems.

Nanodiamond as a carrier for transporting chemotherapy drugs has emerged as a promising strategy for treating cancer. However, several factors have limited its extensive applications in biology, such as low drug loading, tending to aggregate and high drug loss under physiological conditions. In this work, to ensure a high drug capacity and low drug leakage in blood circulation, and especially to ensure that it is delivered to the tumor region, a smart pH-responsive drug delivery system is designed and prepared using doxorubicin (DOX) adsorbed onto PEGylated nanodiamond in sodium citrate medium (ND–PEG–DOX/Na3Cit, NPDC). The system can significantly enhance cellular uptake to exert a therapeutic effect in comparison to the free drug. And more importantly, DOX was released in a sustained and pH-dependent manner, exhibiting excellent stability under physiological conditions. In addition, NPDC could enter into cells via both the clathrin- and caveolae-mediated endocytosis pathways, and then the dissociated DOX migrated into the nucleus to block the growth of cancer cells. Furthermore, NPDC can significantly inhibit cell migration and change the cell cycle. Excitingly, the NPDC system was very smart for the effective enrichment at the tumor site in vivo and enhancing antitumor efficiency with low toxicity beyond conventional DOX treatment in cancer cells and a nude mouse model. So this study introduces a simple and effective strategy to design a promising drug delivery platform for improving the biomedical applications of the smart nanodiamond carriers.

Phototherapy is widely studied with the development of photothermal nanomaterials. However, the laser power density for reaching effective phototherapy is still high and dangerous for normal tissues. In this research, based on multi-functional polydopamine, we proposed a general strategy to design diverse core–shell nanoparticles with different surface charges, and synthesized a targeted nanoplatform, AuNS@PDA–PEI–FA (APP), by coupling gold nanostar (AuNS) with polyethylenimine–folate (PEI–FA). Owing to the electrostatic interaction, the as-prepared APP can anchor a negatively-charged photosensitizer, indocyanine green (ICG), for photothermal and photodynamic synergistic cancer therapy. The APP–ICG is able to realize the targeted phototherapy for tumor cells even at the low power laser density of 0.33 W cm−2 both in vitro and in vivo. Furthermore, APP–ICG is not only a treatment nanoplatform but also a diagnosis agent. The integrative diagnosis results can be acquired by dual imaging technologies: the near-infrared fluorescence images and the photothermal images acquired by an in vivo imaging system and a thermal imaging camera, respectively. This new nanoplatform is a good diagnosis and treatment system and has the potential for further theranostics application.

This paper deals with controller parameterisation method of adaptive H∞ control for polynomial Hamiltonian systems (PHSs) with disturbances and unknown parameters. We design a simplified co...

This paper addresses the problem of outage characterization of an ambient backscatter communication system with a pair of passive tag and reader. In particular, an exact expression for the effective channel distribution is derived. Then, the outage probability at the reader is analyzed rigorously. Since the expression contains an infinite sum, a tight truncation error bound has been derived to facilitate precise numerical evaluations. Furthermore, an asymptotic expression is provided for high signal-to-noise ratio (SNR) regime., Comment: IEEE Communications Letter, 4 figures

Oxygen-related defects in the intrinsic metal-oxide films restrict the transportation and collection processes of photogenerated carriers from the perovskite film to charge transport layers, which obstruct the applications of metal-oxide films in perovskite solar cells (PSCs). In this study, fluorine as an anion dopant was introduced to modify the oxygen-related defects in the intrinsic zinc oxide (ZnO). The impact of fluorine concentration on the structural, electrical, and optical characteristics of solution-processed ZnO films was systematically investigated. When the fluorine concentration was optimized to 15%, fluorine-doped ZnO (ZnO:F) film exhibited multiple advantageous effects, such as large crystalline size, low oxygen-related defect state density, good hydrophobic surface, and high conductivity. Furthermore, ZnO:F films with various fluorine concentrations as electron transport layers (ETLs) were introduced into the PSCs. The PSCs based on the ZnO:F ETL with the fluorine concentration of 15% yielded a maximum power conversion efficiency of 16.23% owing to the improvements of short-circuit current and fill factor. Meanwhile, the thermochemical stability of the device based on the ZnO:F ETL was also significantly improved.

The large-sized naked-eye three-dimensional (3D) display is a critical device in the real-time topographic survey for deep-sea scientific research. As a core component, the low-impedance transparent conductive indium tin oxide (ITO) thin-film electrode lacks a reliable industrial preparation method. In the 3D display, the grating element with a low-resistance ITO film electrode should have a good binocular parallax to drive the display favorably. However, an increase in the ITO film temperature during deposition may induce its crystallization, and its etching residue may cause a short circuit between the ITO electrodes and abnormal display operation. In this work, we propose a simple and straightforward technique to produce amorphous thin ITO films by controlling the water vapor flow rate during the deposition process. The obtained ITO amorphous thick film (300 nm) can be etched without leaving residues on the display surface, ensuring vivid display performance of the 3D display. A field test employing the 3D display, consisting of a 3D parallax barrier and a two-dimensional (2D) display, does not exhibit a short-circuit phenomenon caused by residues encountered in previous devices. This work makes the 3D display applicable for the real-time topographic survey on the basis of both satisfying the nonetching residue and the decrease of the resistance value.

The maximum eigenvalue captures the signal correlation well, and the minimum eigenvalue also captures the noise characteristics well, thus the spectrum sensing algorithm based on the maximum and minimum eigenvalue gets better detection performance. This paper considers various combination algorithms based on maximum and minimum eigenvalues, and proposes some new spectrum sensing algorithms based on maximum and minimum eigenvalue which includes well known algorithm as its special case. Simulation result for multi-user, multi-antenna and multi-path scenarios shows the effectiveness of the proposed algorithms. In particular, the algorithm based on the product and sum of the maximum and minimum eigenvalues (α-MMEP and α-MMES) showed the best detection performance.

To modify the stoichiometry and enhance electronic transportation of electron transport layers (ETLs) potentially for the large-scale high performance planar perovskite solar cells (PSCs) on the flexible substrate, ZnO films as ETLs with controlled stoichiometry are fabricated by magnetron sputtering method under a mixture working gases of Ar and O 2 at room temperature. The impact of Ar/O 2 ratios on the structural, electrical, and optical properties of ZnO films is systematically investigated. The X-ray photoelectron spectroscopy results indicate that the sputtered ZnO films with controlled stoichiometry are successfully achieved. For the proper deposition condition with Ar/O 2 ratio of 1:4, ZnO film exhibits large-size grains, low defect states density, and good optical crystalline quality. Furthermore, the sputtered ZnO films deposited under various Ar/O 2 ratios are introduced into the PSCs as ETLs. The photovoltaic performance of the PSCs is strongly dependent on the properties of the sputtered ZnO ETLs. Compared with the ZnO ETLs prepared under various Ar/O 2 ratios, the PSCs based on the ZnO ETL deposited under the Ar/O 2 ratio of 1:4 demonstrate the improved short-circuit current and fill factor, contributing to a maximum power conversion efficiency of 16.60%. This study highlights that the sputtered ZnO film is one of promising ETLs for high-efficiency PSCs under low-temperature processing.

In this study, hexagonal barium ferrite thin films have been deposited on Pt(111)/Al2O3(0001) substrates by pulsed laser deposition. The thickness of Pt dependence of crystallographic structure and magnetic properties has been studied. X-ray diffraction θ-2θ reveals the films have a good c-axis orientation perpendicular to the film plane. Furthermore, pole figure analysis discovers that the crystallinity of films is greatly improved by Pt buffer layer and the highest degree of orientation is prepared at 20-nm-thick Pt. It is also observed from scanning electron microscope and atomic force microscopy that the BaM film with 20-nm-thick Pt is formed as hexagonal shaped and has smaller than 2 nm of roughness. Magnetic hysteresis loops show the saturation magnetization ( ${\rm{M}}_{{\rm{s}}}$ ), coercivity ( ${\rm{H}}_{{\rm{c}}}$ ), and uniaxial anisotropy field ( ${\rm{H}}_{{\rm{k}}}$ ) are greatly depended on the thickness of Pt buffer layer. Consequently, films with 20-nm Pt buffer layer have the highest ${\rm{M}}_{{\rm{s}}}$ of ${\rm{358\,emu/ cm}}^{3}$ and ${\rm{H}}_{{\rm{k}}}$ of 16.7 kOe which are comparable with the theoretical value of BaM bulk.

Ambient backscatter is an emerging green communication technology that exploits the environmental radio frequency (RF) signals to enable passive devices to communicate with each other. This paper investigates channel capacity and outage performance of ambient backscatter communication systems. Specifically, a calculation method is proposed to facilitate capacity analysis, and the ambient backscatter system capacities are derived in the case of four different RF signals. It is surprisingly found that the channel capacity is obtained when the RF signals are not equiprobably backscattered by tag, and that the capacity with complex Gaussian RF signals is not exactly twice that with real ones for the ambient backscatter communication systems. Then, the outage probability and its asymptotic value in the high signal-to-noise ratio regime are obtained. Since the exact outage expression consists of an infinite number of terms, a tight truncation error bound is derived to reasonably estimate the number of effective terms for numerical simulation. Finally, simulation results are provided to corroborate theoretical analysis.

This paper investigates the problem of adaptive robust simultaneous stabilization (ARSS) of two dissipative Hamiltonian systems (DHSs), and proposes a number of results on the controller parameterization design. Firstly, an adaptiveH∞control design approach is presented by using the dissipative Hamiltonian structural for the case that there are both external disturbances and parametric uncertainties in two DHSs. Secondly, an algorithm for solving tuning parameters of the controller is proposed using symbolic computation. The proposed controller parameterization method avoids solving Hamilton-Jacobi-Issacs (HJI) equations and the obtained controller is easier as compared to some existing ones. Finally, an illustrative example is presented to show that the ARSS controller obtained in this paper works very well.

In this work, a novel and universal sandwich-type electrochemiluminescence (ECL) immunosensor was constructed for the sensitive and specific detection of alpha fetal protein (AFP), in which the MoS 2 nanosheets surface was modified using polyethylenimine (PEI) polymer with plentiful amino-groups (MoS 2 -PEI) for warranting their positively charged interface and thereby a large amount of negatively charged gold nanoparticles (AuNPs) were electrostatically adsorbed to form MoS 2 -PEI-Au nanocomposites. Meanwhile, the synthesized Au@BSA nanoparticles were utilized to immobilize molecule recognition probe secondary antibodies (Ab 2 ) and signal probe numerous luminol molecules, respectively. Upon the optimization of assay conditions, the proposed immunosensor displayed wide linear range from 0.0001 ng/mL to 200.0 ng/mL with limit of detection of 1.0 × 10 −5 ng/mL. Moreover, this immunosensor was employed to analyze AFP in real human serum samples with favorable results. The presented immunosensing strategy may provide great potential in the assay of other clinically biomarkers.

For an orthogonal transform based single-pixel imaging (OT-SPI), to accelerate its speed while degrading as little as possible of its imaging quality, the normal way is to artificially plan the sampling path for optimizing the sampling strategy based on the characteristic of the orthogonal transform. Here, we propose an optimized sampling method using a Deep Q-learning Network (DQN), which considers the sampling process as decision-making, and the improvement of the reconstructed image as feedback, to obtain a relatively optimal sampling strategy for an OT-SPI. We verify the effectiveness of the method through simulations and experiments. Thanks to the DQN, the proposed single-pixel imaging technique is capable of obtaining an optimal sampling strategy directly, and therefore it requires no artificial planning of the sampling path there, which eliminates the influence of the imperfect sampling path planning on the imaging performance.

Perovskite solar cells (PSCs) have received great attention because of their excellent photovoltaic properties especially for the comparable efficiency to silicon solar cells. The electron transport layer (ETL) is regarded as a crucial medium in transporting electrons and blocking holes for PSCs. In this study, CO2 plasma generated by plasma-enhanced chemical vapor deposition (PECVD) was introduced to modify the TiO2 ETL. The results indicated that the CO2 plasma-treated compact TiO2 layer exhibited better surface hydrophilicity, higher conductivity, and lower bulk defect state density in comparison with the pristine TiO2 film. The quality of the stoichiometric TiO2 structure was improved, and the concentration of oxygen-deficiency-induced defect sites was reduced significantly after CO2 plasma treatment for 90 s. The PSCs with the TiO2 film treated by CO2 plasma for 90 s exhibited simultaneously improved short-circuit current (JSC) and fill factor. As a result, the PSC-based TiO2 ETL with CO2 plasma treatment affords a power conversion efficiency of 15.39%, outperforming that based on pristine TiO2 (13.54%). These results indicate that the plasma treatment by the PECVD method is an effective approach to modify the ETL for high-performance planar PSCs.

Early detection of cancer is increasingly important for being considered to increase the survival rate in the treatment process. The past decades years have witnessed the great progress in the biological detection application of gold nanoparticles. Herein, we reported a facile one-pot synthesis process to obtain gold nanoparticles (Au@BSA) with bovine serum albumin (BSA) as a biotemplate following with conjugation of diatrizoic acid (DTA) for a potential X-ray computed tomography (CT) imaging contrast agent (Au@BSA-DTA). The as-prepared biomimetic material was characterized systematically by several techniques. It was shown that the prepared biomaterial is colloid stable under the tested range of pH and temperature. The cell cytotoxicity assay, hemolytic assay and cell morphology observation showed that Au@BSA-DTA has good biocompatibility and hemocompatibility at a concentration of Au even up to 80μg/mL. Besides, the biomimetic material Au@BSA-DTA with double radiodense elements of Au and iodine displayed much stronger CT imaging effect compared with the traditional small molecule contrast agents, which paves the potential clinical application in cancer early diagnosis.

The multi-clearances of breaking type steering trapezoidal mechanism joints influences vehicle steering stability. Hence, to ascertain the influence of clearance value on steering stability, this paper takes the steering mechanism of a certain vehicle type as a prototype that can be simplified into a planar six-bar linkage, then establishes the system dynamic differential equations after considering the two clearances of tie rods and the steering knuckle arms. The influence of the clearance parameters on the movement stability of the steering mechanism is studied using a numerical computation method. Results show that when the two clearances are equal, the planar movement of the tie rods changes from period-doubling to chaos as the clearances increase. When the two clearances are 0.25 mm and 1.5 mm respectively, the planar movements of the two side tie rods come into chaos, causing the steering stability to deteriorate. Moreover, with the increase of clearances, turning moment fluctuates more intensively and the peak value increases.

With the purpose of enriched drug-loading and controlled drug release, a lysozyme-actived nanodiamond-methotrexate prodrug (ND-PEG-GLY-MTX, NPGM) was designed based on ester linkage between glycidylated (GLYlated) nanodiamond and methotrexate (MTX). The resulting NPGM nanoparticles exhibited a high drug load capacity and excellent stability in the physiological environment. In vitro drug release profile demonstrated that MTX could be greatly released from NPGM nanoparticles in acidic environment containing lysozyme, implying the ester bond of NPGM was broken. Confocal microscope and flow cytometer showed that NPGM entered the cells via time, temperature-dependent, energy independent and caveolin-mediated endocytosis and laid in the lysosomes of the cell. Interestingly, the cytotoxicity of NPGM nanoparticles (OFF) in the extracellular medium could be acitived (ON) by lysozyme in lysosomes, due to cleavage of ester linkages when NPGM entered tumor cells. Furthermore, MTT assay and apoptosis detection uncovered that NPGM had better therapeutic effect than that of free MTX. The results show that the well-defined NPGM is a controlled release drug nanoplatform for tumor treatment and the NPGM will open the new nanodrugs window for a broad covalent coupling spectrum of anticancer agents.

Two kinds of modified codewords for space–time block coded spatial modulation (STBC-SM) are presented in this study. The first modified codeword introduces a concept of flexible coefficients into the M-ary phase shift keying STBC-SM. A method is proposed to obtain the optimal flexible coefficients. Moreover, the first modified codewords can also be applied to the systems developed from the STBC-SM. In the second provided codewords, super-orthogonal space–time trellis codes are applied in STBC-SM. Therefore, a higher spectral efficiency is obtained compared with the original STBC-SM. Finally, the simulation results and theoretical analysis demonstrate these performance advantages of the two kinds of modified codewords for STBC-SM.

In order to improve the utilization efficiency of motor train-sets, a Randomized Swap Differential Evolution algorithm (RSDE) is proposed. For the motor train-sets scheduling model with multiple hub stations, the “adjacent node” is taken as the selection range of the connected trains, and the optimization model of the motor train-sets based on the directed graph is established. To satisfy the continuity, an improved priority decoding method, applicable to any situation where trains run in pair, is proposed for generating the initial population and for decoding the individual into the operational tasks that motor train-sets undertakes in turn. In order to apply the differential evolution algorithm to the combinatorial optimization problem, a random permutation operator is proposed based on group theory. Considering the difference of evolutionary information carried by individuals, the adaptive regulatory shrinkage factor is proposed. A novel selection strategy is adopted to keep trial subjects as much as possible. The Wuhan-Guangzhou passenger line is taken as the research object, and the performance of the proposed algorithm is tested. The simulation results show that the algorithm can achieve better optimization performance compared with other several algorithms listed.