Channel Estimation for OTFS System over Doubly Spread Sparse Acoustic Channels

This paper addresses sparse channels estimation problem for the generalized linear models(GLM)in the orthogonal time frequency space(OTFS)underwater acoustic(UWA)system.OTFS works in the delay-Doppler domain,where timevarying channels are characterized as delay-Doppler impulse responses.In fact,a typical doubly spread UWA channel is associated with several resolvable paths,which exhibits a structured sparsity in the delayDoppler domain.To leverage the structured sparsity of the doubly spread UWA channel,we develop a structured sparsity-based generalized approximated message passing(GAMP)algorithm for reliable channel estimation in quantized OTFS systems.The proposed algorithm has a lower computational complexity compared to the conventional Bayesian algorithm.In addition,the expectation maximum algorithm is employed to learn the sparsity ratio and the noise variance.Simulation and experimental results show that the proposed algorithm has superior performance and low computational complexity for quantized OTFS systems.

Rapid and durable oxygen reduction reaction enabled by a perovskite oxide with self-cleaning surface

The growth of electrochemically inert segregation layers on the surface of solid oxide fuel cell cathodes has become a bottleneck restricting the development of perovskite-structured oxygen reduction catalysts.Here,we report a new discovery in which enriched Ba and Fe ions on the near-surface of Nd_(1/2)Ba_(1/2)Co_(1/3)Fe_(1/3)Mn_(1/3)O_(3-δ)spontaneously agglomerate into dispersed Ba_(5)Fe_(2)O_(8) nanoparticles and maintain a highly active and durable perovskite structure on the surface.This unique surface selfcleaning phenomenon is related to the low average potential energy of Ba_(5)Fe_(2)O_(8),which is grown on the near-surface layer.The electrochemically inert Ba_(5)Fe_(2)O_(8) segregation layer on the near-surface of the perovskite catalyst achieves self-cleaning by regulating the formation energy of enriched metal oxides.This self-cleaned perovskite surface exhibits an ultrafast oxygen exchange rate,high catalytic activity for the oxygen reduction reaction,and good adaptability to the actual working conditions of solid oxide fuel cell stacks.This study paves a new way for overcoming the stubborn problem of perovskite catalyst surface deactivation and enriches the scientific knowledge of surface catalysis.

Al2O3陶瓷膏体3D打印挤出成型流变性

陶瓷膏体3D打印挤出成型工艺中,膏体具有低粘度,高稠度和流变性是陶瓷膏体配制需要保证的关键性能,对坯体的密度、成形精度等有较大影响,进一步影响陶瓷器件的成品率。陶瓷膏体的流变性受较多因素影响,本研究通过单因素实验和正交实验研究了固相含量、分散剂含量、pH值和球磨时间对陶瓷膏体流变性能的影响,获得了适应于3D打印挤出成型工艺流变性的A12O3陶瓷膏体,并利用得出的膏体进行打印成型实验和性能分析。研究结果表明:随着固含量的增加,膏体的粘度逐渐增加,流变性能下降。相反,随着分散剂含量和球磨时间的增加,膏体的粘度先减小后增加,而流变性能先增加后减小。另外,随着膏体pH值的升高,粘度先增大后减小,而流变性能先减小后逐渐增大。当固相含量、分散剂含量、pH值和球磨时间分别为51vol.%、0.3vol.%、3和36h时,可以获得具有较好流变性能的陶瓷膏体。

面向骨科植入物的仿生多孔结构设计与制造方法

采用激光选区熔化及陶瓷光固化技术制备了具有多孔特征的金属骨支架与陶瓷骨支架,采用压缩试验评价了两种骨支架的力学性能,采用体外培养MC3T3-E1细胞的方式评估了骨支架的生物相容性。研究结果表明,支架不规则度和孔隙率的变化均会影响支架的力学性能与生物性能;金属支架具有更优良的力学性能,陶瓷支架具有更接近松质骨的力学性能;不规则孔隙有助于细胞附着,使骨支架具有更好的生物相容性。

陶瓷3D打印技术的研究进展

3D打印技术作为新一代成型技术,具有成型速度快以及精度高等优点,采用该技术制作的多功能陶瓷零件在工业、航空、医疗等领域有广阔的应用前景。本文主要对陶瓷3D打印技术进行介绍,且分析了陶瓷3D打印技术的国内外发展情况,在陶瓷3D打印过程中,通过比较和分析陶瓷3D打印技术的工作原理、最新研究成果以及应用领域,指出陶瓷3D打印技术的一些优势和缺陷,并且对陶瓷3D打印技术的发展方向进行了展望。

State-of-the-Art Analysis and Perspectives for Peer-to-Peer Energy Trading

As a promising solution to address the“energy trilemma”confronting human society,peer-to-peer(P2P)energy trading has emerged and rapidly developed in recent years.When carrying out P2P energy trading,customers with distributed energy resources(DERs)are able to directly trade and share energy with each other.This paper summarizes and analyzes the global development of P2P energy trading based on a comprehensive review of related academic papers,research projects,and industrial practice.Key aspects in P2P energy trading are identified and discussed,including market design,trading platforms,physical infrastructure and information and communication technology(ICT)infrastructure,social science perspectives,and policy.For each key aspect,existing research and practice are critically reviewed and insights for future development are presented.Comprehensive concluding remarks are provided at the end,summarizing the major findings and perspectives of this paper.P2P energy trading is a growing field with great potential and opportunities for both academia and industry across the world.

不同鸡种TRNAL-AAG基因序列比较分析

本研究利用目标区域捕获测序技术对TRNAL-AAG(transfer RNA leucine(antico-don AAG))基因进行序列测定,找出不同鸡种TRNAL-AAG基因序列上的差异,为鸡抗病育种研究提供基础材料。利用MEGA X软件对25个鸡种和6种其他鸟类的基因序列进行比对分析,统计SNPs位点和Indel位点,并构建系统进化树进行分析。结果发现该基因SNP共19个,有义突变16个,均集中在序列第47位和第50位,可作为该基因有关抗病的候选SNPs位点。另外,该基因在25个鸡品种间高度保守,没有碱基插入或缺失且相似性高达98%,仅有雪山草鸡和北京油鸡存在一个有义突变,体现两品种在该基因上的多态性。进化树将31种鸟类分为两类:雪山草鸡和北京油鸡及所选6种鸟类聚为一类,其余鸡种聚为一类。说明鸟类品种间的同源性较小,不同鸟类品种TRNAL-AAG基因具有较为丰富的遗传多样性。

Synthesis and application of a hydrophobic hypercrosslinked polymeric resin for removing VOCs from humid gas stream

A hydrophobic hypercrosslinked polymeric resin LC-1 was prepared and characterized. The properties of LC-1 resin were compared with those of a commercial hypercrosstinked polymer NDA-201 resin. In addition, the dynamic adsorption of trichloroethylene （TCE） onto LC-1 under dry and humid conditions at 303 K was investigated, the result shows that LC-1 possesses high hydrophobic property and can remove TCE from gas stream without effect of high humidity efficiently.

An Overview of the Smart Grid in Great Britain

This paper presents an overview of the current status of the development of the smart grid in Great Britain(GB).The definition,policy and technical drivers,incentive mechanisms,technological focus,and the industry's progress in developing the smart grid are described.In particular,the Low Carbon Networks Fund and Electricity Network Innovation Competition projects,together with the rollout of smart metering,are detailed.A more observable,controllable,automated,and integrated electricity network will be supported by these investments in conjunction with smart meter installation.It is found that the focus has mainly been on distribution networks as well as on real-time flows of information and interaction between suppliers and consumers facilitated by improved information and communications technology,active power flow management,demand management,and energy storage.The learning from the GB smart grid initiatives will provide valuable guidelines for future smart grid development in GB and other countries.

Physiological performance of three calcifying green macroalgae Halimeda species in response to altered seawater temperatures

The effects of seawater temperature on the physiological performance of three Halimeda species were studied for a period of 28 d.Five treatments were established for Halimeda cylindracea,Halimeda opuntia and Halimeda lacunalis,in triplicate aquaria representing a factorial temperature with 24°C,28°C,32°C,34°C and 36°C,respectively.The average Fv/Fm of these species ranged from 0.732 to 0.756 between 24°C and 32°C but declined sharply between 34°C(0.457±0.035)and 36°C(0.122±0.014).Calcification was highest at 28°C,with net calcification rates(Gnet)of(20.082±2.482)mg/(g·d),(12.825±1.623)mg/(g·d)and(6.411±1.029)mg/(g·d)for H.cylindracea,H.opuntia and H.lacunalis,respectively.Between 24°C and 32°C,the specific growth rate(SGR)of H.lacunalis(0.079%–0.110%d–1)was lower than that of H.cylindracea(0.652%–1.644%d–1)and H.opuntia(0.360%–1.527%d–1).Three Halimeda species gradually bleached at 36°C during the study period.Malondialdehyde(MDA)and proline levels in tissues of the three Halimeda were higher in 34–36°C than those in 24–32°C.The results indicate that seawater temperature with range of 24–32°C could benefit the growth and calcification of these Halimeda species,however,extreme temperatures above 34°C have negative impacts.The measured physiological parameters also revealed that H.cylindracea and H.opuntia displayed broader temperature tolerance than H.lacunalis.

Integrated energy efficiency evaluation of a multi-source multi-load desalination micro-energy network

With increasing global shortage of fresh water resources,many countries are prioritizing desalination as a means of utilizing abundantly available seawater resources.Integrated energy efficiency evaluation is a scientific method for the quantitative analysis of energy efficiency based on multiple indicators and is very useful for investment,construction,and scientific decision-making for desalination projects.In this paper,the energy efficiency evaluation of the micro energy network (MEN) of desalination for multi-source and multi-load is studied,and the basic idea of comprehensive energy efficiency evaluation is analyzed.The process includes the use of a MEN model to establish an integrated energy efficiency evaluation index system,taking into consideration energy,equipment,economic,environmental,and social factors.A combined evaluation method considering subjective and objective comprehensive weights for multi-source multi-load desalination MENs is proposed to evaluate the energy efficiency of desalination and from multiple perspectives.

单相多流态下缠绕管流动换热数值模拟模型研究

由于缠绕管特殊的结构形式,缠绕管内层流向湍流的转变雷诺数范围较大。对缠绕管管内流体单相流动多种流态状态进行数值模拟,数值计算结果与实验关联式进行比较。在缠绕管管内流动为层流状态下,采用laminar model数值计算缠绕管换热特性结果与实验关联式相比,误差小,模型适应性好。而管内流动雷诺数高于临界雷诺数,采用低雷诺数湍流模型SSTk-ω模型能够较好模拟计算管内传热特性,当管内流态逐渐向旺盛湍流转变,采用高雷诺数湍流模型realizable k-ε模型或RNG k-ε模型进行模拟计算Nu较为准确。

Detail description of Lithophyllum okamurae(Lithophylloideae,Corallinales), a widely distributed crustose coralline alga in marine ecosystems

Lithophyllum okamurae is one of the important encrusting coralline algae,which plays important roles as primary producer,carbonate sediment builder,and habitat provider in the marine ecosystems.In this study,L.okamurae was collected from tropical coast of Sanya,and firstly described based on both detailed morph-anatomical characteristics and molecular studies of typic DNA sequences.The structure of the thalli of L.okamurae was pseudoparenchymatous construction with radially organized dimerous organizations in the crustose portion.The pseudoparenchymatous construction were composed of three parts,including 1 to 3 layers of epithelia cells which had flatten to round outermost walls,one layer of square or rectangular cells of the hypothallia and multiple layers of square or elongated rectangular peripheral cells.Palisade cells were observed,and the cells of the contiguous vegetative filaments were connected by secondary pit-connections with cell fusions absent.The carposporangial conceptacles,the spermatangial conceptacles,the bisporangial conceptacles and the tetrasporangial conceptacles were observed,and all these four kinds of conceptacles were uniporate.The spermatangial conceptacles were slightly convex and buried at shallow depths in the thalli tissues,and the carposporangial conceptacles and asexual conceptacles were protruding and conical.Phylogenetic studies based on DNA barcoding markers of 18 S rDNA,COI,rbc L and psb A revealed that L.okamurae clustered with the closest relation of L.atlanticum,and formed a distinct branch.Based on the comparative anatomical features and the molecular data,the detailed description of the valid species of L.okamurae was firstly given in this study to provide theoretical basis for algae resources utilization and conservation in marine ecosystems.

Poly(vinylpyridine) adsorbent for the removal of SIPA from its aqueous solution

Poly（vinylpyridine） WH-225 resin was prepared and characterized. Compared with the commercial hypercrosslinked adsorbent NDA-100 and macroporous adsorbent XAD-4 resins, the newly synthesized poly（vinylpyridine） WH-225 resin exhibited the highest adsorption capacity toward SIPA from aqueous solution.

超薄金修饰的钯电极用于乙醇安培传感研究

超薄贵金属膜具有独特的结构和功能,创新其制备方法,拓展其电化学应用具有重要意义。通过在镀Pd的玻碳电极(GCE)上电沉积欠导电Se超薄膜并作为模板,再与HAuCl4进行原电池置换反应,制备了超薄Au膜修饰的镀Pd电极(AuSe/Pd/GCE),并在碱性条件下采用循环伏安法研究了AuSe/Pd/GCE对乙醇的电催化氧化性能影响,并构建了乙醇安培传感器。研究表明,与裸Pd电极相比,AuSe/Pd/GCE对乙醇的电催化氧化活性更高;在最优条件下,修饰电极对乙醇的线性检测范围为0.025~10.000 mmol·L^-1,灵敏度为0.94(mA·cm^-2)/(mmol·L^-1),优于多数已报道的方法。此种以欠导电物质均匀电沉积薄膜为模板,采用原电池置换反应制备超薄贵金属膜的新方法有望在纳米电催化剂的制备及电催化与电分析研究中广泛应用。

基于碲膜置换制备粗糙金电极的无酶葡萄糖电化学传感器

高粗糙度薄层贵金属纳米结构的界面组装对研制高性能的电化学传感器具有重要意义。以玻碳电极(GCE)上电沉积锯齿状形貌的半导体碲(Te)膜为模板,再将其与HAuCl4进行原电池置换反应,制备了条棒状的粗糙Au薄膜修饰电极(AuTe-R/GCE)。在碱性环境中采用循环伏安法研究了AuTe-R/GCE对葡萄糖的电催化氧化性能,并藉此构建了无酶葡萄糖电化学传感器。结果表明,与普通的镀金GCE(Aucon/GCE)和裸Au电极相比,AuTe-R/GCE对葡萄糖的电催化氧化活性更高;在最优条件下,采用恒电位计时安培法检测了葡萄糖浓度,AuTe-R/GCE对葡萄糖的线性检测范围(LDR)为0.01~2.00 mmol·L^-1,灵敏度为3.8 mA·mmol^-1·cm^-2,检测下限(LOD)为55 nmol·L^-1;且该无酶葡萄糖电化学传感器抗干扰能力强,稳定性好。以半导体碲膜制备特定形貌与高粗糙度薄层纳米Au的方法具有简便、快捷和低成本等优点,有望在高活性纳米电催化剂的界面组装及其电化学性能研究中被广泛应用。

接枝型阳离子淀粉絮凝剂对石材废水的絮凝降浊性能与机理研究

混凝/絮凝工艺是去除废水中悬浮胶体颗粒、降低浊度的有效手段.本研究以一种常见的天然高分子材料——淀粉为原材,以丙烯酰胺和甲基丙烯酰氧乙基三甲基氯化铵为共聚单体,采用接枝共聚技术,开发了一系列接枝链分布相同、但电荷密度及平均接枝链链长不同的接枝型阳离子淀粉改性絮凝剂:淀粉接枝共聚丙烯酰胺-聚甲基丙烯酰氧乙基三甲基氯化铵(St-G).并以一种具有高浊度特征的行业废水——石材废水为研究对象,详细讨论了St-G的结构因素(电荷密度与平均接枝链链长)及环境因素(絮凝剂投加量和pH等)对其絮凝性能的影响,结合絮凝后上清液Zeta电位、絮体结构的动态监测结果以及扩展DLVO(Derjguin-Landau-Verwey-Overbeek)胶体稳定理论等,详细探究了其絮凝机理.研究结果表明,St-G对石材废水的絮凝性能明显优于传统无机混凝剂聚合氯化铝,St-G对石材废水的除浊作用主要是电荷碎片机制为主导,且与黏结架桥作用协同作用的结果.随着St-G电荷密度的增加,其浊度去除率增加而对应最佳絮凝剂用量减少,且絮体破碎后恢复因子增加;而絮体尺寸、絮体生长速度及其破碎因子均与St-G平均接枝链链长呈正相关.扩展DLVO理论结果也表明,St-G与石材废水胶体颗粒间总相互作用能为负值,且与电荷密度呈负相关,其中电荷密度最大的St-G1总相互作用能最低,最易发生电中和混凝作用,具有最佳的降浊效果.综上可知,St-G的制法安全简便、降浊效果显著、绿色环保且价格低廉,在石材加工等行业废水处理中有着良好的应用前景.

High-capacity porous carbons prepared by KOH activation of activated carbon for supercapacitors

High-performance supercapacitor electrode materials are prepared from the commercially available activated carbon （AC） through a facile and low-cost chemical activation method. The obtained results show that AC activated by KOH with an alkali/carbon ratio of 6/1 （ACK6） possesses a specific surface area of 3405 m^2/g, a large pore volume of 2.01 cm^3/g, and exhibits the highest initial specific capacitance of 335 F/g at the current density of 0.5 A/g in 6 mol/L KOH, and 85% coloumbic efficiency for 5000 cycles at 20 mV/s.

Isolation of toxic compounds from wild Phaeocystis globosa

Two new compounds, namely taenialactam C and globorin A（1 and 2）, as well as six known compounds,cornoside（3）, 2-phenylethyl-b-D-glucoside（4）, 3-isopropyl-5-acetoxycyclohexene-2-one-1（5）, 4-methyl-phenol（6）, 5-[（2S）-2-aminobutyl]-2-methyl-phenol（7）, and 1-（4-methylphenyl）-1-propanone（8） were isolated from wild Phaeocystis globosa. The structures of the new compounds were established by detailed spectroscopic analysis and by comparison with spectral data of related known compounds.The structures of the known compounds were identified by comparing their spectroscopic data with those reported in the literature. This paper also reports toxicity properties of the eight compounds against the brine shrimp Artemia salina and juvenile Epinephelus akaara fish. Some of these compounds showed significant lethality on the brine shrimp A. salina and the juvenile E. akaara fish.

微芯片中磁性液滴的生成与操控综述

磁性液滴以其微尺度、多相流属性和非接触式操控特性,近年来因在生物细胞分离、靶向药物治疗等方面的成功应用受到来自科学界和企业界学者们的广泛关注,如何操控磁性液滴精确运动到设定位置是主要难点。本工作从磁性液滴的生成方式、运动基本机理及操控方法三个方面,对目前存在的主流磁性液滴生成与操控的方法进行了整理。目前对于磁性液滴的操控方法可分为三类,第一类是永磁铁-机械式操控方法:该方法将永磁铁放置在一个机械移动平台上,通过移动平台改变永磁铁与微芯片的距离进而改变磁场,最终实现操控液滴的目的;第二类是电磁铁-电气式操控方法:以高速照相机拍摄液滴运动的位置误差为检测信号,将检测信号传递给控制器,最终通过改变电磁铁的磁场强度实现对液滴的操控;第三类是永磁铁/电磁铁-电气式混合控制方法:通过将两者的优缺点进行互补,最终达到更优控制。总结了目前存在方法的缺陷和难点,指出了磁性液滴在未来发展中的一些可行的研究方法和研究方向。要点:(1)综述了磁性液滴的应用和合成,总结了磁性液滴处理的主要方法的优缺点。(2)综述了磁液滴形成的方法,包括磁动力法、多相流法和电动力法。(3)总结了磁性液滴在磁场中的力学分析,给出了磁性液滴的动力学方程。(4)综述了磁性液滴的操控方法,包括永磁铁操控、电磁铁操控和混合操控,并分析了各自的特点。