Effect of surface Cr/C infiltration on microstructure,mechanical properties and wear resistance of high chromium cast iron

A new type of high chromium cast iron(HCCI)was prepared,and its microstructure,mechanical properties,and abrasion resistance were investigated systematically.Results showed that after surface carburizing and chromizing,the microstructure of HCCI mainly consists of martensite,boride(M_(2)B),and carbide(M_(7)C_(3)),accompanied with a large amount of secondary precipitations M_(23)C_(6).Moreover,the morphology and hardness of the carbide and boride in HCCI change little,while the volume fraction of carbide and boride increases from 16.23%to 23.16%.This effectively increases the surface hardness of HCCI from 64.53±0.50 HRC to 66.58±0.50 HRC,with the result that the surface of HCCI possesses a better abrasion resistance compared to the center position.Furthermore,the wear mechanism of HCCI changes from micro-plowing to micro-cutting with the increase of surface hardness.

An Estimation Method for Relationship Strength in Weighted Social Network Graphs

Previous works mainly focused on estimating direct relationship strength in social networks. If two users are not directly connected in a social network, there is no direct relationship. In order to estimate the relationship strength between two indirectly connected users as well as directly connected users, this paper proposes an estimation method for relationship strength in weighted social network graphs, which is based on the trust propagation strategy and the estimation of direct relationship strength. Our method considers the length of a relationship path, the number of relationship paths and the edge weights (direct relationship strength) along with a relationship path to estimate the strength of indirect relationship. Then it synthesizes the direct and indirect relationship strength to represent the strength of relationship between two users in social net- works. Thus our method can fully estimate the relationship strength between any two users in a social network no matter whether they are directly connected or not.

Quantum Homomorphic Signature with Repeatable Verification

In January 2015,the first quantum homomorphic signature scheme was proposed creatively.However,only one verifier is allowed to verify a signature once in this scheme.In order to support repeatable verification for general scenario,we propose a new quantum homomorphic signature scheme with repeatable verification by introducing serial verification model and parallel verification model.Serial verification model solves the problem of signature verification by combining key distribution and Bell measurement.Parallel verification model solves the problem of signature duplication by logically treating one particle of an EPR pair as a quantum signature and physically preparing a new EPR pair.These models will be beneficial to the signature verification of general scenarios.Scheme analysis shows that both intermediate verifiers and terminal verifiers can successfully verify signatures in the same operation with fewer resource consumption,and especially the verified signature in entangled states can be used repeatedly.

Continuous-Variable Quantum Network Coding Based on Quantum Discord

Establishing entanglement is an essential task of quantum communication technology.Beyond entanglement,quantum discord,as a measure of quantum correlation,is a necessary prerequisite to the success of entanglement distribution.To realize efficient quantum communication based on quantum discord,in this paper,we consider the practical advantages of continuous variables and propose a feasible continuous-variable quantum network coding scheme based on quantum discord.By means of entanglement distribution by separable states,it can achieve quantum entanglement distribution from sources to targets in a butterfly network.Compared with the representative discrete-variable quantum network coding schemes,the proposed continuous-variable quantum network coding scheme has a higher probability of entanglement distribution and defends against eavesdropping and forgery attacks.Particularly,the deduced relationship indicates that the increase in entanglement is less than or equal to quantum discord.

Controlled Quantum Network Coding Without Loss of Information

Quantum network coding is used to solve the congestion problem in quantum communication,which will promote the transmission efficiency of quantum information and the total throughput of quantum network.We propose a novel controlled quantum network coding without information loss.The effective transmission of quantum states on the butterfly network requires the consent form a third-party controller Charlie.Firstly,two pairs of threeparticle non-maximum entangled states are pre-shared between senders and controller.By adding auxiliary particles and local operations,the senders can predict whether a certain quantum state can be successfully transmitted within the butterfly network based on the Z-{10>,|1>}basis.Secondly,when trans-mission fails upon prediction,the quantum state will not be lost,and it will sill be held by the sender.Subsequently,the controller Charlie re-prepares another three-particle non-maximum entangled state to start a new round.When the predicted transmission is successful,the quantum state can be transmitted successfully within the butterfly network.If the receiver wants to receive the effective quantum state,the quantum measurements from Charlie are needed.Thirdly,when the transmission fails,Charlie does not need to integrate the X-{1+>,1->}basis to measure its own particles,by which quantum resources are saved.Charlie not only controls the effective transmission of quantum states,but also the usage of classical and quantum channels.Finally,the implementation of the quantum circuits,as well as a flow chart and safety analysis of our scheme,is proposed.

SM algorithms-based encryption scheme for large genomic data files

With the rapid development of the genomic sequencing technology,the cost of obtaining personal genomic data and effectively analyzing it has been gradually reduced.The analysis and utilization of genomic dam gradually entered the public view,and the leakage of genomic dam privacy has attracted the attention of researchers.The security of genomic data is not only related to the protection of personal privacy,but also related to the biological information security of the country.However,there is still no.effective genomic dam privacy protection scheme using Shangyong Mima(SM)algorithms.In this paper,we analyze the widely used genomic dam file formats and design a large genomic dam files encryption scheme based on the SM algorithms.Firstly,we design a key agreement protocol based on the SM2 asymmetric cryptography and use the SM3 hash function to guarantee the correctness of the key.Secondly,we used the SM4 symmetric cryptography to encrypt the genomic data by optimizing the packet processing of files,and improve the usability by assisting the computing platform with key management.Software implementation demonstrates that the scheme can be applied to securely transmit the genomic data in the network environment and provide an encryption method based on SM algorithms for protecting the privacy of genomic data.

Quantum Secret Broadcast for Wireless Quantum Networks

In wireless quantum networks, nodes communicate by means of pre-distribution for entangled pairs and relay path establishment for quantum teleportation. However, simple point-to-point communication seriously restricts the efficiency of quantum communication. Inspired by sharing idea of quantum secret sharing (QSS), which is based on three collaborative nodes with pre-shared GHZ (Greenberger-Horne-Zeilinger) states, we propose a quantum secret broadcast scheme to improve network performance. In a cluster net-work cored on three parties of QSS, three cluster heads with pre-shared GHZ states are senders, while cluster members are receivers. One cluster head encodes secret messages on auxiliary particles by performing certain operations on them with GHZ particles, then three cluster heads measure their own par-ticles and broadcast measurement results honestly. Based on the specific correlation of measurement results and secret messages, all receivers can re-cover the secret messages. Furthermore, to prevent eavesdropping, cluster heads can update an encoding key periodically. Analysis shows the proposed scheme is more efficient than previous schemes in wireless quantum net-works, especially when the number of receivers is larger. Besides, in the proposed scheme, attacks on quantum channel based on GHZ state can be detected, and eavesdroppers cannot recover messages correctly for lack of suitable decoding key.

都江堰地区繁殖期鸟类多样性

都江堰地区位于生物多样性热点地区,具有丰富的鸟类多样性,但迄今仍缺乏全面的鸟类物种名录。本研究于2016年5月至2019年8月,在都江堰地区采用固定样线法开展了鸟类多样性调查,结合历史文献共记录该地区鸟类17目61科311种。其中留鸟184种(59.2%),夏候鸟68种(21.9%),冬候鸟35种(11.3%),旅鸟24种(7.7%);繁殖鸟类252种(81.0%);雀形目鸟类212种(68.2%);国家I级重点保护鸟类9种(2.9%),国家II级重点保护鸟类50种(16.1%),中国特有鸟类15种(4.8%)。研究发现,常绿-落叶阔叶混交林及灌丛中的鸟类物种最多,而常绿针叶林和竹林中的鸟类物种最少。都江堰地区鸟类群落丰富度的峰值出现在1,580-1,890 m海拔段,在1,890-2,200 m海拔段最低,呈现出单峰分布格局。作为生物多样性热点地区和旅游热点地区,都江堰今后应避免发展大规模单一的人工经济林,以更好地维系该地区丰富的鸟类多样性,并加强对该地区生物多样性的监测、研究和保护。

Dynamic data auditing scheme for big data storage

When users store data in big data platforms,the integrity of outsourced data is a major concern for data owners due to the lack of direct control over the data.However,the existing remote data auditing schemes for big data platforms are only applicable to static data.In order to verify the integrity of dynamic data in a Hadoop big data platform,we presents a dynamic auditing scheme meeting the special requirement of Hadoop.Concretely,a new data structure,namely Data Block Index Table,is designed to support dynamic data operations on HDFS(Hadoop distributed file system),including appending,inserting,deleting,and modifying.Then combined with the MapReduce framework,a dynamic auditing algorithm is designed to audit the data on HDFS concurrently.Analysis shows that the proposed scheme is secure enough to resist forge attack,replace attack and replay attack on big data platform.It is also efficient in both computation and communication.