Waveform Design of DFRC System for Target Detection in Clutter Environment

Dual-function radar and communication (DFRC) has recently drawn significant attention due to its enormous potential. This letter deals with waveform design of DFRC to improve target detectability embedded in clutter environment while guaranteeing the service quality of communication users. Our design objective is to maximize the output signal-to-clutter-plus-noise ratio (SCNR) of multiple-input multiple-output (MIMO) radar, subject to worst-case received symbol errors at communication users. Coordinate descent (CD) as an efficient iteration algorithm is proposed to solve above optimization problem, which splits high-dimensional problem into multiple one-dimensional problem. Furthermore, we introduce Dinkelbach algorithm (DA) to increase rate of convergence, which is an efficient way to reduce complexity. Finally, simulation results are presented to illustrate the effectiveness of the proposed techniques

Cloning and characterization of microRNAs from wheat (Triticum aestivum L.)

A small RNA library was used to identify 58 miRNAs from 43 miRNA families from wheat (Triticum aestivum L.), and 46 potential targets were predicted

The critical role of intracellular zinc in adenosine A2 receptor activation induced cardioprotection against reperfusion injury

Exogenous zinc can protect cardiac cells from reperfusion injury, but the exact roles of endogenous zinc in the pathogenesis of reperfusion injury and in adenosine A2 receptor activation-induced cardioprotection against reperfusion injury remain unknown. Adenosine A1/A2 receptor agonist 5′-(N-ethylcarboxamido) adenosine (NECA) given at reperfusion reduced infarct size in isolated rat hearts subjected to 30 min ischemia followed by 2 h of reperfusion. This effect of NECA was partially but significantly blocked by the zinc chelator N,N,N′,N′-tetrakis-(2-pyridylmethyl) ethylenediamine (TPEN), and ZnCl2 given at reperfusion mimicked the effect of NECA by reducing infarct size. Total tissue zinc concentrations measured with inductively coupled plasma optical emission spectroscopy (ICPOES) were decreased upon reperfusion in rat hearts and this was reversed by NECA. NECA increased intracellular free zinc during reperfusion in the heart. Confocal imaging study showed a rapid increase in intracellular free zinc in isolated rat cardiomyocytes treated with NECA. Further experiments revealed that NECA increased total zinc levels upon reperfusion in mitochondria isolated from isolated hearts. NECA attenuated mitochondrial swelling upon reperfusion in isolated hearts and this was inhibited by TPEN. Similarly, NECA prevented the loss of mitochondrial membrane potential (ΔΨm) caused by oxidant stress in cardiomyocytes. Finally, both NECA and ZnCl2 inhibited the mitochondrial metabolic activity. NECA-induced cardioprotection against reperfusion injury is mediated by intracellular zinc. NECA prevents reperfusion-induced zinc loss and relocates zinc to mitochondria. The inhibitory effects of zinc on both the mPTP opening and the mitochondrial metabolic activity may account for the cardioprotective effect of NECA

Over-Expression of PDGFR-β Promotes PDGF-Induced Proliferation, Migration, and Angiogenesis of EPCs through PI3K/Akt Signaling Pathway

The proliferation, migration, and angiogenesis of endothelial progenitor cells (EPCs) play critical roles in postnatal neovascularization and re-endothelialization following vascular injury. Here we evaluated whether the over-expression of platelet-derived growth factor receptor-β (PDGFR-β) can enhance the PDGF-BB-stimulated biological functions of EPCs through the PDGFR-β/phosphoinositide 3-kinase (PI3K)/Akt signaling pathway. We first confirmed the expression of endogenous PDGFR-β and its plasma membrane localization in spleen-derived EPCs. We then demonstrated that the PDGFR-β over-expression in EPCs enhanced the PDGF-BB-induced proliferation, migration, and angiogenesis of EPCs. Using AG1295 (a PDGFR kinase inhibitor), LY294002 (a PI3K inhibitor), and sc-221226 (an Akt inhibitor), we further showed that the PI3K/Akt signaling pathway participates in the PDGF-BB-induced proliferation, migration, and angiogenesis of EPCs. In addition, the PI3K/Akt signaling pathway is required for PDGFR-β over-expression to enhance these PDGF-BB-induced phenotypes

Neural Network-Based Adaptive Backstepping Control for Hypersonic Flight Vehicles with Prescribed Tracking Performance

An adaptive neural control scheme is proposed for a class of generic hypersonic flight vehicles. The main advantages of the proposed scheme include the following: (1) a new constraint variable is defined to generate the virtual control that forces the tracking error to fall within prescribed boundaries; (2) RBF NNs are employed to compensate for complex and uncertain terms to solve the problem of controller complexity; (3) only one parameter needs to be updated online at each design step, which significantly reduces the computational burden. It is proved that all signals of the closed-loop system are uniformly ultimately bounded. Simulation results are presented to illustrate the effectiveness of the proposed scheme

Robust beamforming for dual‐function radar‐communication with imperfect channel state information

Abstract Dual‐function radar and communication (DFRC) have recently received significant attention as an effective way to alleviate spectrum congestion and reduce system costs. Joint transmit beamforming plays a critical role in DFRC systems, as it can effectively reduce mutual interference and improve the performance of both the radar and communication systems. This paper investigates the problem of robust beamforming design with imperfect channel state information (CSI) to ensure communication performance while optimizing radar performance. Considering elliptically bounded CSI errors, the objective function is designed to minimize the radar loss function, which is related to the radar transmit beam pattern, subject to worst‐case signal‐to‐interference‐plus‐noise ratio constraints at each user, which ensure fairness between users. An efficient algorithm based on semidefinite relaxation and the S‐procedure is proposed to solve the non‐convex problem. Simulation results are presented to illustrate the effectiveness of the proposed robust beamforming scheme, which can reduce the impact of channel errors

Mapping Matrix Design and Improved Belief Propagation Decoding Algorithm for Rate-Compatible Modulation

Rate-compatible modulation (RCM) can achieve adaptive transmission in a variable channel environment. However, there are two problems with conventional RCM. Firstly, there is a large number of four rings in the mapping matrix of the conventional RCM, which blocks the delivery of messages in the decoding. Secondly, in the conventional decoding of RCM, the soft information of the last decoding will be discarded when cyclic redundancy check (CRC) is failed, which decreases the performance significantly. In order to address these two problems, in this paper, we propose a new method to construct a mapping matrix without four rings (MMwoFR) and an improved belief propagation (IBP) algorithm for RCM decoding. On the one hand, by using MMwoFR, the constructed matrix is able to prevent the existence of four rings which have much side influence of reliability performance. On the other hand, the IBP is able to make the most use of the soft information in RCM decoding. Simulation results show that using MMwoFR and IBP can bring at least 12% goodput gain for RCM at the high signal-to-noise ratio (SNR) region while maintaining the same performance in the low and moderate SNR regions. Moreover, complexity analysis shows that the new scheme has comparable complexity compared with a conventional RCM

Enhancement of Terahertz Emission by Silver Nanoparticles in a Liquid Medium

Due to higher molecular density, lower ionization potential, and a better self-healing property compared with gases, liquid targets have been used for laser-induced terahertz generation for many years. In this work, a liquid target used for terahertz radiation is embedded with silver nanoparticles (Ag NPs), which makes the material have both the fluidity of liquids and conductivity of metals. Meanwhile, the experimental setup is easier to implement than that of liquid metals. Polyvinyl alcohol (PVA) is used as a stabilizing agent to avoid precipitation formation. It is observed that the power of 0.5 THz radiation from the Ag NP suspension is five times stronger than that from liquid water in identical experimental conditions. In addition, the reusability of the material is investigated using multiple excitations. UV–visible spectroscopy and TEM imaging are carried out to analyze the target material after each excitation. As a result, quasispherical Ag NP suspensions show good reusability for several excitations and only a decrease in particle concentration is observed. By contrast, the chain-like Ag NP suspension shows poor stability due to PVA damage caused by intense laser pulses, so it cannot be used in a recyclable manner

AFM/XPS Analysis of the Growth and Architecture of Oriented Molecular Monolayer by Spin Cast Process and Its Cross-Linking Induced by Hyperthermal Hydrogen

We used atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS) to comprehensively study the growth and the cross-linking of dotriacontane (C32H66) nanofilms that were deposited on a silicon wafer by the spin-coating process. It was found that the molecular structure of the nanofilms changed with C32H66 concentration at the given spin speed, of which a monolayer of oriented C32H66 molecules, formed at lower deposition concentrations, was composed of a perpendicular orientation state with the molecular long-chain axis perpendicular to the substrate surface and a parallel orientation state, while the perpendicular state was essentially dominant when the nanofilm was formed at higher deposition concentrations. The shortening of the first perpendicular layer in AFM topography could be attributed to the mixing of both parallel and perpendicular lamellas in the first layer. XPS analysis indicated that the average thickness of the layer almost linearly increased with the C32H66 concentration. The monolayer of C32H66 film could be cross-linked by a hyperthermal hydrogen-induced cross-linking (HHIC) at a few eV via kinetic collision to cleave C-H bonds. The water contact angle measurement of extensive HHIC on C32H66 nanofilms disclosed that the static contact angle decreased with the treatment time (or fluence) and saturated after full cross-linking of the film