Guidance Law and Neural Control for Hypersonic Missile to Track Targets

Hypersonic technology plays an important role in prompt global strike. Because the flight dynamics of a hypersonic vehicle is nonlinear, uncertain, and highly coupled, the controller design is challenging, especially to design its guidance and control law during the attack of a maneuvering target. In this paper, the sliding mode control (SMC) method is used to develop the guidance law from which the desired flight path angle is derived. With the desired information as control command, the adaptive neural control in discrete time is investigated ingeniously for the longitudinal dynamics of the hypersonic missile. The proposed guidance and control laws are validated by simulation of a hypersonic missile against a maneuvering target. It is demonstrated that the scheme has good robustness and high accuracy to attack a maneuvering target in the presence of external disturbance and missile model uncertainty

Charge Distribution Reconstruction in a Bubbling Fluidized Bed Using a Wire-Mesh Electrostatic Sensor

The presence of electrostatic charge in a bubbling fluidized bed influences the operation of the bed. In order to maintain an effective operation, the electrostatic charges in different positions of the bed should be monitored. In this paper a wire-mesh electrostatic sensor is introduced to reconstruct the charge distribution in a bubbling fluidized bed. The wire-mesh sensor is fabricated by two mutually perpendicular strands of insulated wires. A Finite Element Model is built to analyze the sensing characteristics of the sensor. The sensitivity distributions of each wire electrode and the whole sensor are obtained from the model, which proves that wire-mesh electrostatic sensor has a higher and more uniform sensitivity distribution than single wire sensors. Experiments were conducted in a gravity drop test rig to validate the reconstruction method. Experimental results show that the charge distribution can be reconstructed when sand particles pass through the cross section of the sensor

Electromagnetically induced transparency of interacting Rydberg atoms with two-body dephasing

We study electromagnetically induced transparency in a three-level ladder type configuration in ultracold atomic gases, where the upper level is an electronically highly excited Rydberg state. An effective distance dependent two-body dephasing can be induced in a regime where dipole-dipoles interaction couple nearly degenerate Rydberg pair states. We show that strong two-body dephasing can enhance the excitation blockade of neighboring Rydberg atoms. Due to the dissipative blockade, transmission of the probe light is reduced drastically by the two-body dephasing in the transparent window. The reduction of transmission is accompanied by a strong photon-photon anti-bunching. Around the Autler-Townes doublets, the photon bunching is amplified by the two-body dephasing, while transmission is largely unaffected. Besides relevant to the ongoing Rydberg atom studies, our study moreover provides a setting to explore and understand two-body dephasing dynamics in many-body systems

Embryonic Stem Cells Improve Cardiac Function in Doxorubicin-Induced Cardiomyopathy Mediated Through Multiple Mechanisms

Doxorubicin (DOX) is an effective anti neoplastic agent used for the treatment of a variety of cancers. Unfortunately, its use is limited as this drug induces cardiotoxicity and heart failure as a side effect. There is no report that describes whether transplanted embryonic stem (ES) cells or their conditioned medium (CM) in DOX-induced cardiomyopathy (DIC) can repair and regenerate myocardium. Therefore, we transplanted ES cells or CM in DIC to examine apoptosis. fibrosis, cytoplasmic vacuolization, and myofibrillar loss and their associated Akt and ERK pathway. Moreover, we also determined activation of endogenous c-kit(+ve) cardiac stem cells (CSCs), levels of FIGF and IGF-1, growth factors required for c-kit cell activation, and their differentiation into cardiac myocytes, which also contributes in cardiac regeneration and improved heart function. We generated DIC in C57Bl/6 mice (cumulative dose of DOX 12 mg/kg body weight. IP), and animals were treated with ES cells, CM, or cell culture medium in controls. Two weeks post-DIC, ES cells or CM transplanted hearts showed a significant (p \u3c 0.05) decrease in cardiac apoptotic nuclei and their regulation with Akt and ERK pathway. Cardiac fibrosis observed in the ES cell or CM groups was significantly less compared with DOX and cell culture medium groups (p \u3c 0.05). Next, cytoplasmic vacuolization and myofibrillar loss was reduced (p \u3c 0.05) following treatment with ES cells or CM. Moreover, our data also demonstrated increased levels of c-kit(+ve) CSCs in ES cells or CM hearts and differentiated cardiac myocytes from these CSCs, suggesting endogenous cardiac regeneration. Importantly, the levels of HFG and IGF-1 were significantly increased in ES cells or CM transplanted hearts. In conclusion, we reported that transplanted ES cells or CM in DIC hearts significantly decreases various adverse pathological mechanisms as well as enhances cardiac regeneration that effectively contributes to improved heart function

An Auction-based Coordination Strategy for Task-Constrained Multi-Agent Stochastic Planning with Submodular Rewards

In many domains such as transportation and logistics, search and rescue, or cooperative surveillance, tasks are pending to be allocated with the consideration of possible execution uncertainties. Existing task coordination algorithms either ignore the stochastic process or suffer from the computational intensity. Taking advantage of the weakly coupled feature of the problem and the opportunity for coordination in advance, we propose a decentralized auction-based coordination strategy using a newly formulated score function which is generated by forming the problem into task-constrained Markov decision processes (MDPs). The proposed method guarantees convergence and at least 50% optimality in the premise of a submodular reward function. Furthermore, for the implementation on large-scale applications, an approximate variant of the proposed method, namely Deep Auction, is also suggested with the use of neural networks, which is evasive of the troublesome for constructing MDPs. Inspired by the well-known actor-critic architecture, two Transformers are used to map observations to action probabilities and cumulative rewards respectively. Finally, we demonstrate the performance of the two proposed approaches in the context of drone deliveries, where the stochastic planning for the drone league is cast into a stochastic price-collecting Vehicle Routing Problem (VRP) with time windows. Simulation results are compared with state-of-the-art methods in terms of solution quality, planning efficiency and scalability.Comment: 17 pages, 5 figure

PREF: Phasorial Embedding Fields for Compact Neural Representations

We present an efficient frequency-based neural representation termed PREF: a shallow MLP augmented with a phasor volume that covers significant border spectra than previous Fourier feature mapping or Positional Encoding. At the core is our compact 3D phasor volume where frequencies distribute uniformly along a 2D plane and dilate along a 1D axis. To this end, we develop a tailored and efficient Fourier transform that combines both Fast Fourier transform and local interpolation to accelerate na\"ive Fourier mapping. We also introduce a Parsvel regularizer that stables frequency-based learning. In these ways, Our PREF reduces the costly MLP in the frequency-based representation, thereby significantly closing the efficiency gap between it and other hybrid representations, and improving its interpretability. Comprehensive experiments demonstrate that our PREF is able to capture high-frequency details while remaining compact and robust, including 2D image generalization, 3D signed distance function regression and 5D neural radiance field reconstruction

(R)-N-(Biphenyl-4-yl)-tert-butane­sulfinamide

In the title compound, C16H19NOS, the dihedral angle between the two aromatic rings is 38.98 (8)°. The crystal structure is stabilized by N—H⋯O hydrogen bonds, which link neighbouring mol­ecules into chains running parallel to the a axis

Novel glucose sensor based on enzymeimmobilized 81° tilted fiber grating

We demonstrate a novel glucose sensor based on an optical fiber grating with an excessively tilted index fringe structure and its surface modified by glucose oxidase (GOD). The aminopropyltriethoxysilane (APTES) was utilized as binding site for the subsequent GOD immobilization. Confocal microscopy and fluorescence microscope were used to provide the assessment of the effectiveness in modifying the fiber surface. The resonance wavelength of the sensor exhibited red-shift after the binding of the APTES and GOD to the fiber surface and also in the glucose detection process. The red-shift of the resonance wavelength showed a good linear response to the glucose concentration with a sensitivity of 0.298nm(mg/ml)-1 in the very low concentration range of 0.0∼3.0mg/ml. Compared to the previously reported glucose sensor based on the GOD-immobilized long period grating (LPG), the 81° tilted fiber grating (81°-TFG) based sensor has shown a lower thermal cross-talk effect, better linearity and higher Q-factor in sensing response. In addition, its sensitivity for glucose concentration can be further improved by increasing the grating length and/or choosing a higher-order cladding mode for detection. Potentially, the proposed techniques based on 81°-TFG can be developed as sensitive, label free and micro-structural sensors for applications in food safety, disease diagnosis, clinical analysis and environmental monitoring