一种面向联盟链Hyperledger Fabric的并发冲突事务优化方法

随着区块链技术应用的普及,联盟链Hyperledger Fabric(简称Fabric)已成为知名区块链开源平台,并得到广泛关注.然而Fabric仍受困于并发事务间冲突问题,冲突发生时会引发大量无效交易上链,导致吞吐量下降,阻碍其发展.对于该问题,现有面向块内冲突的方案缺乏高效的冲突检测和避免方法,同时现有研究往往忽略区块间冲突对吞吐量的不利影响.提出了一种Fabric的优化方案Fabric-HT(fabric with high throughput),从区块内和区块间2方面入手,有效降低事务间并发冲突和提高系统吞吐量.针对区块内事务冲突,提出了一种事务调度机制,根据块内冲突事务集定义了一种高效数据结构——依赖关系链,识别具有“危险结构”的事务并提前中止,合理调度事务和消除冲突;针对区块间事务冲突,将冲突事务检测提前至排序节点完成,建立以“推送-匹配”为核心的冲突事务早期避免机制.在多场景下开展大量实验,结果表明Fabric-HT在吞吐量、事务中止率、事务平均执行时间、无效事务空间占用率等方面均优于对比方案.Fabric-HT吞吐量最高可达Fabric的9.51倍,是最新优化方案FabricSharp的1.18倍;空间利用率上相比FabricSharp提升了14%.此外,Fabric-HT也表现出较好的鲁棒性和抗攻击能力.

基于Fabric的海量交易数据上链预处理机制

Hyperledger Fabric是一种国内外广泛使用的联盟链框架,在基于Fabric技术的一些业务中具有协同组织众多、交易操作频繁、事务冲突增加等特点。Fabric采用的多版本并发控制技术能够在一定程度上解决部分交易冲突,提升系统并发性,但其机制不完善,会出现部分交易数据无法正常上链存储的问题。为了实现海量交易数据完整、高效、可信的上链存储,提出一种基于Fabric预言机的数据上链预处理机制。设计海量数据冲突预处理(MCPP)方法,通过检测、监听、延时提交、事务加锁、重排序缓存等方式实现主键冲突交易数据的完整上链。引入数据传输保障措施,在传输过程中利用非对称加密技术防止恶意节点伪造认证信息,确保交易数据链外处理前后的一致性。通过理论分析和实验结果表明,该机制可有效解决联盟链平台中海量交易数据上链时的并发冲突问题,当交易数据规模达到1 000和10 000时,MCPP的时效性比LMLS提高了38%和21.4%,且成功率接近100%,具有高效性和安全性,同时在无并发冲突情况下不影响Fabric系统性能。

基于CP-ABE算法的Fabric隐私保护模型

传统区块链系统缺少对区块数据的隐私保护。结合CP-ABE(基于属性加密的密文策略)算法和IPFS(星际文件系统),提出一种可以对Fabric区块链实现访问控制的隐私保护模型CP-PPM。CP-PPM的数据所有者可以灵活设置访问控制策略。仿真结果表明,与现有Fabric区块链系统相比,CP-PPM模型支持细粒度的访问控制,具有更强的隐私保护效果;CP-ABE算法可以安全初始化,对数据的加解密效率更高,同时增强了区块链系统的存储性能。

2D multifunctional devices:from material preparation to device fabrication and neuromorphic applications

Neuromorphic computing systems,which mimic the operation of neurons and synapses in the human brain,are seen as an appealing next-generation computing method due to their strong and efficient computing abilities.Two-dimensional (2D) materials with dangling bond-free surfaces and atomic-level thicknesses have emerged as promising candidates for neuromorphic computing hardware.As a result,2D neuromorphic devices may provide an ideal platform for developing multifunctional neuromorphic applications.Here,we review the recent neuromorphic devices based on 2D material and their multifunctional applications.The synthesis and next micro–nano fabrication methods of 2D materials and their heterostructures are first introduced.The recent advances of neuromorphic 2D devices are discussed in detail using different operating principles.More importantly,we present a review of emerging multifunctional neuromorphic applications,including neuromorphic visual,auditory,tactile,and nociceptive systems based on 2D devices.In the end,we discuss the problems and methods for 2D neuromorphic device developments in the future.This paper will give insights into designing 2D neuromorphic devices and applying them to the future neuromorphic systems.

Recent advances in fabrication and functions of neuromorphic system based on organic field effect transistor

The development of various artificial electronics and machines would explosively increase the amount of information and data,which need to be processed via in-situ remediation.Bioinspired synapse devices can store and process signals in a parallel way,thus improving fault tolerance and decreasing the power consumption of artificial systems.The organic field effect transistor(OFET)is a promising component for bioinspired neuromorphic systems because it is suitable for large-scale integrated circuits and flexible devices.In this review,the organic semiconductor materials,structures and fabrication,and different artificial sensory perception systems functions based on neuromorphic OFET devices are summarized.Subsequently,a summary and challenges of neuromorphic OFET devices are provided.This review presents a detailed introduction to the recent progress of neuromorphic OFET devices from semiconductor materials to perception systems,which would serve as a reference for the development of neuromorphic systems in future bioinspired electronics.

Surface Morphology and Thermo-Electrical Energy Analysis of Polyaniline (PANI) Incorporated Cotton Fabric

With the exponential development in wearable electronics,a significant paradigm shift is observed from rigid electronics to flexible wearable devices.Polyaniline(PANI)is considered as a dominant material in this sector,as it is endowed with the optical properties of both metal and semiconductors.However,its widespread application got delineated because of its irregular rigid form,level of conductivity,and precise choice of solvents.Incorporating PANI in textile materials can generate promising functionality for wearable applications.This research work employed a straightforward in-situ chemical oxidative polymerization to synthesize PANI on Cotton fabric surfaces with varying dopant(HCl)concentrations.Pre-treatment using NaOH is implemented to improve the conductivity of the fabric surface by increasing the monomer absorption.This research explores the morphological and structural analysis employing SEM,FTIR and EDX.The surface resistivity was measured using a digital multimeter,and thermal stability is measured using TGA.Upon successful polymerization,a homogenous coating layer is observed.It is revealed that the simple pre-treatment technique significantly reduces the surface resistivity of Cotton fabric to 1.27 kΩ/cm with increasing acid concentration and thermal stability.The electro-thermal energy can also reach up to 38.2°C within 50 s with a deployed voltage of 15 V.The modified fabric is anticipated to be used in thermal regulation,supercapacitor,sensor,UV shielding,antimicrobial and other prospective functional applications.

Efficient and selective removal of Pb(Ⅱ) from landfill leachate using L-serine-modified polyethylene/polypropylene nonwoven fabric synthesized via radiation grafting technique

In this study,to efficiently remove Pb(Ⅱ) from aqueous environments,a novel L-serine-modified polyethylene/polypropylene nonwoven fabric sorbent(NWF-serine)was fabricated through the radiation grafting of glycidyl methacrylate and subsequent L-serine modification.The effect of the absorbed dose was investigated in the range of 5–50 kGy.NWF-serine was characterized by Fourier transform infrared spectroscopy,thermogravimetric analysis,and scanning electron microscopy.Batch adsorption tests were conducted to investigate the influences of pH,adsorption time,temperature,initial concentration,and sorbent dosage on the Pb(Ⅱ) adsorption performance of NWF-serine.The results indicated that Pb(Ⅱ) adsorption onto NWF-serine was an endothermic process,following the pseudo-second-order kinetic model and Langmuir isotherm model.The saturated adsorption capacity was 198.1 mg/g.NWF-serine exhibited Pb(Ⅱ) removal rates of 99.8% for aqueous solutions with initial concentrations of 100 mg/L and 82.1% for landfill leachate containing competitive metal ions such as Cd,Cu,Ni,Mn,and Zn.Furthermore,NWF-serine maintained 86% of its Pb(Ⅱ) uptake after five use cycles.The coordination of the carboxyl and amino groups with Pb(Ⅱ) was confirmed using X-ray photoelectron spectroscopy and extended X-ray absorption fine structure analysis.

Near-zero-adhesion-enabled intact wafer-scale resist-transfer printing for high-fidelity nanofabrication on arbitrary substrates

There is an urgent need for novel processes that can integrate different functional nanostructures onto specific substrates,so as to meet the fast-growing need for broad applications in nanoelectronics,nanophotonics,and fexible optoelectronics.Existing direct-lithography methods are difficult to use on fexible,nonplanar,and biocompatible surfaces.Therefore,this fabrication is usually accomplished by nanotransfer printing.However,large-scale integration of multiscale nanostructures with unconventional substrates remains challenging because fabrication yields and quality are often limited by the resolution,uniformity,adhesivity,and integrity of the nanostructures formed by direct transfer.Here,we proposed a resist-based transfer strategy enabled by near-zero adhesion,which was achieved by molecular modification to attain a critical surface energy interval.This approach enabled the intact transfer of wafer-scale,ultrathin-resist nanofilms onto arbitrary substrates with mitigated cracking and wrinkling,thereby facilitating the in situ fabrication of nanostructures for functional devices.Applying this approach,fabrication of three-dimensional-stacked multilayer structures with enhanced functionalities,nanoplasmonic structures with~10 nm resolution,and MoS2-based devices with excellent performance was demonstrated on specific substrates.These results collectively demonstrated the high stability,reliability,and throughput of our strategy for optical and electronic device applications.

From manual to automated fabric inspection

Uster,Switzerland,28th March 2024–Uster Technologies offers a flexible solution to upgrade fabric inspection from manual to automated.Integration in existing production lines is quick and easy,and the data flow also brings extra benefits.It means fabric producers can significantly improve their yield with fast,accurate quality monitoring.

基于Hyperledger Fabric框架区块链基础平台安全沙箱机制研究

区块链基础平台基于Hyperledger Fabric框架开发,主要包括智能合约、客户端、共识机制等。数据以沙箱方式传输到数据需求方,智能合约会根据指定策略控制沙箱的访问权限和时效性,阅后即焚,保障数据提供方的数据所有权。区块链基础平台可实现数据使用可溯、可管,采用原数据目录上链的形式进行数据共享,以智能合约定义数据使用规则,数据使用记录上链,全程记录数据调用信息,确保数据安全、不可篡改,数据可信、可追踪。

基于区块链Fabric架构的个体学信系统设计

目前,个人学信数据的完整性和准确性难以达到用人单位的需求,教育机构的大量学习记录和成果被闲置。针对此问题,文章设计了基于区块链Fabric架构的个体学信系统。该系统由业务系统层、区块层、服务层、应用层组成,涉及学习者、用人单位、教育机构和颁证部门4个主体,通过授权的方式实现区块链交易和共识机制。

Review on nanocomposites fabricated by mechanical alloying

Composites are composed of multiphase materials, where each phase has specific properties that differ from those of the other phases which can effect on the whole properties of composite. Nanocomposites are class of materials that contain at least one phase in the nanometric size range and can be produced by any suitable technique for preparing nanomaterials. Composites are an interesting class of materials that have recently been used in numerous applications, including structural, biomedical, electronics, and environmental applications. In composites, reinforcements might be fibers, particulates, or whiskers. Mechanical alloying(MA) is a promising technique for producing nanocomposite materials that are difficult or impossible to prepare via conventional techniques. In this review, we provide an overview of nanocomposites prepared by the MA process. The mechanism of milling and other milling parameters are overviewed, and insights into sintering categories and parameters are also presented.

Progress in Research on Nanometer Al_2O_3 Fabricated by Sol-Gel Method

Nanometer Al_2O_3 is one of new types of functional materials with broad application and development prospects in the future. The basic principle and ways of nanometer Al_2O_3 fabricated using sol-gel technique were introduced, and the factors affecting nanometer Al_2O_3 fabricated using sol-gel method were analyzed. The progress in research on nanometer Al_2O_3 and the application fields of nanometer Al_2O_3 were reviewed. The existing problems and the problems prospect for nanometer Al_2O_3 were pointed out.

Experimental research on behavior of 460 MPa high strength steel I-section columns under cyclic loading

To investigate the seismic behavior of I-section columns made of 460 MPa high strength steel （HSS）, six specimens were tested under constant axial load and cyclic horizontal load. The specimens were designed with different width-to-thickness ratios and loaded under different axial load ratios. For each specimen, the failure mode was observed and hysteretic curve was measured. Comparison of different specimens on hysteretic characteristic, energy dissipation capacity and deformation capacity were further investigated. Test results showed that the degradation of bearing capacity was due to local buckling of flange and web. Under the same axial load ratio, as width-to-thickness ratio increased, the deformation area of local buckling became smaller. And also, displacement level at both peak load and failure load became smaller. In addition, the full extent of hysteretic curve, energy dissipation capacity, ultimate story drift angle decreased, and capacity degradation occurred more rapidly with the increase of width-to-thickness ratio or axial load ratio. Based on the capacity of story drift angle, limiting values which shall not be exceeded are suggested respectively for flange and web plate of 460 MPa HSS I-section columns when used in SMFs and in IMFs in the case of axial load ratio no more than 0.2. Such values should be smaller when the axial load ratio increases.

Anisotropic NdFeB Magnet Fabricated by Single Stroke Hot Deformation

The general hot deformation process consists of two steps, hot pressing and die-upsetting in order to obtain the anisotropic NdFeB magnet. This is the first report that the high anisotropy NdFeB magnets can be fabricated by single stroke hot deforming the isotropic magnet. The magnetic properties of those materials are: coercivity iHc ～11 kOe, remanence Br ～12 kG, and the maximum energy product (BH)max ～28 MG.Oe.

The journey of multifunctional bone scaffolds fabricated from traditional toward modern techniques

As a bone scaffold,meeting all basic requirements besides dealing with other bone-related issues-bone cancer and accelerated regeneration-is not expected from traditional scaffolds,but a newer class of scaffolds called multifunctional.From a clinical point of view,being a multifunctional scaffold means reducing in healing time,direct costs-medicine,surgery,and hospitalization-and indirect costs-loss of mobility,losing job,and pain.The main aim of the present review is following the multifunctional bone scaffolds trend to deal with both bone regeneration and cancer therapy.Special consideration is given to different fabrication techniques which have been applied to yield these materials spanning from traditional to modern ones.Moreover,the hierarchical structure of bone plus bone cancers and available medicines to them are introduced to familiarize the potential reader of review with the pluri-disciplinary essence of the field.Eventually,a brief discussion relating to the future trend of these materials is provided.

面向Fabric的跨链可行性方法研究

随着区块链技术不断地发展,Fabric框架已成为目前最主流的联盟链框架。面对不同业务需求,区块链研发人员往往为不同的应用场景构建不同的区块链,这种单链架构的业务链面临业务复杂、吞吐率低、拓展难等风险,跨链技术能帮助简单业务链完成互操作从而实现复杂的业务功能。本文综合分析了目前主流跨链技术的优缺点,提出了基于中继链与跨链中间件的跨链模型,并在此模型下基于跨链协议、背书策略交易证明、跨链事务管理实现Fabric跨链智能合约互操作。经过实验与性能分析表明本文提出的方法是可行的。

基于Fabric的城市智慧停车方案设计

为了解决目前城市车位信息不流通、停车系统交易凭证不可靠、停车支付不高效以及数据存储不安全等弊端,提出了基于Fabric区块链的城市智慧停车方案。利用区块链数据共享的特性,允许车位拥有者将空闲车位上传至区块链,实现车位实时共享并保证数据真实;利用预制在区块链上的智能合约,实现停车后自动缴费;利用区块链数据不可篡改且可追溯的特性,保证交易数据的真实性。最后通过搭建分布式区块链系统,并对系统进行测试,验证了该方案的可行性。

基于Hyperledger Fabric与星际文件系统相结合的数据存储框架

利用Hyperledger Fabric和星际文件系统设计了一种新的数据存储框架,使用Hyperledger Fabric的Level DB保存规模较小的状态数据,利用星际文件系统保存账本中大规模的交易数据,并改造了原来的数据存储和数据查询模块。新框架有效扩展了Hyperledger Fabric的存储能力,缓解了记账节点的数据膨胀问题。实验结果表明,新框架在保证安全性的前提下,增加了部分网络延迟,但相对于区块链存储的可扩展性而言,这个代价是可以接受的。

Novel Resonant Accelerometer with Micro Leverage Fabricated by MEMS Technology

For the purpose of improving the precision of the inertial guidance system,it is necessary to enhance the accuracy of the accelerometer.Combining the micro-fabrication processes with resonant sensor technology,a high-resolution inertial-grade novel micro resonant accelerometer is studied.Based on the detecting theory of the resonant sensors,the accelerometer is designed,fabricated,and tested.The accelerometer consists of one proofmass,two micro leverages and two double-ended-tuning-fork （DETF） resonators.The sensing principle of this accelerometer is based on that the natural frequency of the DETF resonator shifts with its axial load which is caused by inertial force.The push-pull configuration of the DETF is for temperature compensation.The two-stage micro leverage mechanisms are employed to amplify the force and increase the sensitivity of the accelerometer.The micro leverage and the resonator are modeled for static analysis and nonlinear modal analysis via theory method and finite element method （FEM）,respectively.The geometrical parameters of them are optimized.The amplification factor of the leverage is 102,and the sensitivity of the resonator on theory is about 62 Hz/g.The samples of the accelerometer are fabricated with deep reactive ion etching （DRIE） technology which can get a high-aspect ratio structure for contributing a greater sensing-capacitance.The measuring results of the samples by scanning electron microscopy （SEM） show that the process is feasible,because of the complete structure,the sound combs and micro leverages,and the acceptable errors.The frequency of the resonator and the sensitivity of the accelerometer are tested via printed circuit board （PCB）,respectively.The result of the test shows that the frequency of the push-resonator is about 54 530 Hz and the sensitivity of the accelerometer is about 55 Hz/g.The amplification factor of the leverage is calculated more accurately because the coupling of the two stages leverage is considered during derivation of the analysis formula.In addition,the novel differential structure of the accelerometer can greatly improve the sensitivity of the accelerometers.