一种水声信道均衡器的混合算法

水声高速相干通信中使用自适应均衡对抗信道在接收信号中产生的码间串扰。目前,1/2分数间隔采样的判决反馈均衡器结构得到了广泛的应用。本文分析了几种自适应算法在此种均衡器结构下的性能,结合浅海水声信道的特点,提出了一种快速卡尔曼滤波和快速自优化最小均方的混合算法,模拟及海试结果表明,该混合算法在计算复杂度、收敛速度以及稳定性方面都有很好的性能,已经应用到了水声实时高速通信系统当中。     

An eco-friendly efficient extractor

A microscale solid-liquid Pyrex extractor is described. The extractor has a novel detachable extraction vessel (H) containing a filter paper cylinder (C) over the reservoir. A filter paper cylinder (C) is firmly placed in the socket (E) with a plug (G) on which the cylinder has been placed. The sample is directly weighed in the extraction vessel (H) and the vessel is clamped (F) to the body (B). Contents in the extraction reservoir (H) are stirred (I) with a magnetic stirrer (J) and heated sufficiently (e.g. at 84.8 °C in using water) by the solvent vapor (D). Easy filtration (C) and continuous outflow (D) of the filtrates out of the reservoir (H) keeps a stable boiling condition (K), rather than batchwise conditions operative in a Soxhlet; this results in rapid and exhaustive extraction. The present extractor (8.0 mL extraction reservoir (H) capacity) equipped with a 25 mL solvent flask (K) was applied to fat extraction from powdered peanut by using 18 mL of ether. The extraction was complete in 30-60 min depending on reflux rate; in contrast, extraction with a commercial micro-Soxhlet device (23.9 mL extraction reservoir capacity) equipped with a 25 mL flask by using 34 mL of the solvent was incomplete in 120 min. Unlike filter paper thimbles used in Soxhlet devices, filter paper cylinder (C) in the new extractor could be reused many times and results in significant savings of the filter paper cylinders. Small reservoir and flask capacities of the new extractor minimize the use of organic solvents. The present apparatus permits fast and efficient extraction, sharply reduces waste, minimizes solvent consumption, and thus should find wide use aiming at the Green Solutions to Global Problems.     

Solving a large dense linear system by adaptive cross approximation

An efficient algorithm for the direct solution of a linear system associated with the discretization of boundary integral equations (in two dimensions) is described without having to compute the complete matrix of the linear system. This algorithm is based on the unitary-weight representation, for which a new construction based on adaptive cross approximation is proposed. This low rank approximation uses only a small part of the entries to construct the adaptive cross representation, and therefore the linear system can be solved efficiently.     

Generalized convolution quadrature with variable time stepping. Part II: Algorithm and numerical results

In this paper we address the implementation of the Generalized Convolution Quadrature (gCQ) presented and analyzed by the authors in a previous paper for solving linear parabolic and hyperbolic convolution equations. Our main goal is to overcome the current restriction to uniform time steps of Lubich's Convolution Quadrature (CQ). A major challenge for the efficient realization of the new method is the evaluation of high-order divided differences for the transfer function in a fast and stable way. Our algorithm is based on contour integral representation of the numerical solution and quadrature in the complex plane. As the main application we consider the wave equation in exterior domains, which is formulated as a retarded boundary integral equation. We provide numerical experiments to illustrate the theoretical results.     

Li Plating Regulation on Fast-Charging Graphite Anodes by a Triglyme-LiNO3 Synergistic Electrolyte Additive

Graphite anodes are prone to dangerous Li plating during fast charging, but the difficulty to identify the rate-limiting step has made a challenging to eliminate Li plating thoroughly. Thus, the inherent thinking on inhibiting Li plating needs to be compromised. Herein, an elastic solid electrolyte interphase (SEI) with uniform Li-ion flux is constructed on graphite anode by introducing a triglyme (G3)-LiNO₃ synergistic additive (GLN) to commercial carbonate electrolyte, for realizing a dendrite-free and highly-reversible Li plating under high rates. The cross-linked oligomeric ether and Li₃N particles derived from the GLN greatly improve the stability of the SEI before and after Li plating and facilitate the uniform Li deposition. When 51 % of lithiation capacity is contributed from Li plating, the graphite anode in the electrolyte with 5 vol.% GLN achieved an average 99.6 % Li plating reversibility over 100 cycles. In addition, the 1.2-Ah LiFePO₄ | graphite pouch cell with GLN-added electrolyte stably operated over 150 cycles at 3 C, firmly demonstrating the promise of GLN in commercial Li-ion batteries for fast-charging applications.     

A fast on-demand preparation of injectable self-healing nanocomposite hydrogels for efficient osteoinduction

Injectable hydrogels have been considered as promising materials for bone regeneration,but their osteoinduction and mechanical performance are yet to be improved.In this study,a novel biocompatible injectable and self-healing nano hybrid hydrogel was on-demand prepared via a fast(within 30 s) and easy gelation approach by reversible Schiff base formed between-CH=O of oxidized sodium alginate(OSA) and-NH_2 of glycol chitosan(GCS) mixed with calcium phosphate nanoparticles(CaP NPs).Its raw materials can be ready in large quantities by a simple synthesis process.The mechanical strength,degradation and swelling behavior of the hydrogel can be readily controlled by simply controlling the molar ratio of-CH=O and-NH_2.This hydrogel exhibits pH responsiveness,good degradability and biocompatibility.The hydrogel used as the matrix for mesenchymal stem cells can significantly induce the proliferation,differentiation and osteoinduction in vitro.These results showed this novel hydrogel is an ideal candidate for applications in bone tissue regeneration and drug delivery.