A Practical Regular LDPC Coded Scheme for Physical-Layer Information Security

In this paper,we aim to design a practical low complexity low-density parity-check(LDPC)coded scheme to build a secure open channel and protect information from eavesdropping.To this end,we first propose a punctured LDPC coded scheme,where the information bits in a codeword are punctured and only the parity check bits are transmitted to the receiver.We further propose a notion of check node type distribution and derive multi-edge type extrinsic information transfer functions to estimate the security performance,instead of the well-known weak metric bit error rate.We optimize the check node type distribution in terms of the signal-to-noise ratio(SNR)gap and modify the progressive edge growth algorithm to design finite-length codes.Numerical results show that our proposed scheme can achieve a lower computational complexity and a smaller security gap,compared to the existing scrambling and puncturing schemes.

Securing offshore resources development:A mathematical investigation into gas leakage in long-distance flexible pipes

Gas flexible pipes are critical multi-layered equipment for offshore oil and gas development.Under high pressure conditions,small molecular components of natural gas dissolve into the polymer inner liner of the flexible pipes and further diffuse into the annular space,incurring annular pressure build-up and/or production of acidic environment,which poses serious challenges to the structure and integrity of the flexible pipes.Gas permeation in pipes is a complex phenomenon governed by various factors such as internal pressure and temperature,annular structure,external temperature.In a long-distance gas flexible pipe,moreover,gas permeation exhibits non-uniform features,and the gas permeated into the annular space flows along the metal gap.To assess the complex gas transport behavior in long-distance gas flexible pipes,a mathematical model is established in this paper considering the multiphase flow phenomena inside the flexible pipes,the diffusion of gas in the inner liner,and the gas seepage in the annular space under varying permeable properties of the annulus.In addition,the effect of a variable temperature is accounted.A numerical calculation method is accordingly constructed to solve the coupling mathematical equations.The annular permeability was shown to significantly influence the distribution of annular pressure.As permeability increases,the annular pressure tends to become more uniform,and the annular pressure at the wellhead rises more rapidly.After annular pressure relief followed by shut-in,the pressure increase follows a convex function.By simulating the pressure recovery pattern after pressure relief and comparing it with test results,we deduce that the annular permeability lies between 123 and 512 m D.The results help shed light upon assessing the annular pressure in long distance gas flexible pipes and thus ensure the security of gas transport in the emerging development of offshore resources.

Robust Beamforming for Secured Wireless Power Transfer in MIMO Magnetic Resonant Coupling System:A Probabilistic Approach

Wireless power transfer(WPT) to support mobile and portable devices is an emerging wireless technique.Among all kinds of approaches,magnetic resonance coupling(MRC) is an excellent one for mid-range WPT,which provides better mobility,flexibility,and convenience due to its simplicity in hardware implementation and longer transmission distances.In this paper,we consider an MRCWPT system with multiple power transmitters,one intended power receiver and multiple unintended power receivers.We investigate the probabilistic robust beamforming designs and provide efficient algorithms to achieve the local optimums under two different criteria,i.e.,total source power minimization problem and min-max unintended receiving power restriction problem.As the problems are quite typical in robust design situations,our proposed robust beamformers can be conveniently applied to other probabilistic robust design problems,thus reduce the complexity as well as improve the beamforming performance.Numerical results demonstrate that the proposed algorithms can significantly improve the performance as well as the robustness of the WPT system.

Secure Transmission Scheme Based on Dual-Thresholds for Simultaneous Wireless Information and Power Transfer

This paper studies a simultaneous wireless information and power transfer system with multiple external eavesdroppers and internal curious users.We model the random network by Poisson cluster process in consideration of the case where eavesdroppers hide around certain targets.Focusing on the users that work in harvesting-transmitting mode with time switching receivers,we establish communication model via time division multiple access.On this basis,we propose a lightweight secure transmission scheme based on dual-thresholds for physical-layer security enhancement,which consists of two protocols applied to the downlink(DL) and uplink(UL) transmission respectively.In the DL,we design a dynamic information-power switching transmission protocol based on signal-to-noise ratio threshold,which provides an opportunistic approach to reform the fixed period allocation of information and power transfer;in the UL,an energy threshold is proposed for users to control the transmission,which is called a user-led on-off transmission protocol.Furthermore,we give a comprehensive performance analysis for the proposed scheme in terms of delay,reliability,security and secrecy throughput.Based on the analysis results,we optimize the two thresholds and the DL-UL allocationcoefficient to maximize the secrecy throughput.Simulation results show the proposed scheme can bring about a substantial secrecy gain.

The Security Correction of Large Consumers Long-Term Direct Power Trading Based on DC Power Transfer Distribution Factor

The experiments of large consumers direct power trading is conducting in china nationwide, and it’s important to the reform of electricity market. To compensated efficiencies in security correction of large consumers direct power trading, a novel security correction method based on DC power transfer distribution factor was proposed. Using the presented method to comply security correction, all the transactions that satisfy the specific requirements of maximizing social welfare are able to enter security correction process, and when the power of transmission line is out of limit, this method avoid the transaction which causes this problem is abandoned directly by introducing supplement transactions. The simulation has shown that the proposed security correction method of large consumers direct power trading based on DC power transfer distribution factor is effective.

Quantum Oblivious Transfer with Reusable Bell State

In cryptography,oblivious transfer(OT)is an important multiparty cryptographic primitive and protocol,that is suitable for many upperlayer applications,such as secure computation,remote coin-flipping,electrical contract signing and exchanging secrets simultaneously.However,some nogo theorems have been established,indicating that one-out-of-two quantum oblivious transfer(QOT)protocols with unconditional security are impossible.Fortunately,some one-out-of-two QOT protocols using the concept of Crepeau’s reduction have been demonstrated not to conform to Lo’s no-go theorem,but these protocols require more quantum resources to generate classical keys using all-or-nothing QOT to construct one-out-of-two QOT.This paper proposes a novel and efficient one-out-of-two QOT which uses quantum resources directly instead of wasting unnecessary resources to generate classical keys.The proposed protocol is not covered by Lo’s no-go theorem,and it is able to check the sender’s loyalty and avoid the attack from the receiver.Moreover,the entangled state of the proposed protocol is reusable,so it can provide more services for the participants when necessary.Compared with otherQOT protocols,the proposed protocol is more secure,efficient,and flexible,which not only can prevent external and internal attacks,but also reduce the required resources and resource distribution time.

Water Security Situation in Haihe River Basin after South-to-North Water Transfer Project

The over-exploitation of water resources in the Haihe River Basin （HRB） has now become a serious problem. This is clearly evidenced by the fact that many local rivers and lakes are drying up and the total amount of over-exploited groundwater has reached over 1000×10^8m^3. It is important to note that the exploitation of water resources in HRB was reasonable before 1979. After 1980, however, over-exploitation happened with an annual average amount of 40×10^8m^3. Both the dry season and rapid economic growth in HRB took place at the same time. Therefore, the over-exploitation of water in HRB was actually the negative result of the conjunction of a continuous dry season and rapid economic growth. So the over-exploitation would not be as serious as it is today if either of the above two stopped. After the first stage of south-to-north water transfer project, the water shortage problem in HRB could be eased for the following reasons： firstly, water transfer project will bring to the Basin 60x108m3 water resources; secondly, a wet season will come back eventually according to natural law of climate variability; finally, its agricultural and industrial use and total water consumption all have decreased from the peak value, so that the groundwater table will raise certainly and ecological water in rivers and lakes that were dried-up will be partly restored. In the future, the main problem of water resources security in HRB will include water pollution, operation risk of the south-to-north water transfer project, groundwater pollution and engineering geological hazards that may be brought by groundwater rise. The proposed countermeasures are as follows： keeping strengthening water demand management, raising water price as well as subsidies for the low- income family and improving other water related policies, preventing and dealing with water pollution seriously and getting fully prepared for the operation of south-to-north water transfer project.

社会保障参与有助于农村土地流转吗?——基于劳动力转移的中介效应

随着我国城乡社会保障制度逐步完善,农民对土地的依赖得到缓解,农村劳动力非农就业比例提高,农村土地流转供给不断增加。基于中国家庭追踪调查2012—2018年数据,构建了双重固定效应模型,旨在考察社会保障参与对农村土地流转的影响,同时分析了劳动力转移的中介效应。研究结果表明:参与新型农村养老保险对农村土地转出具有显著影响;参与新型农村合作医疗保险对于农村土地转出的影响并不显著,但是显著抑制农村土地转入;劳动力转移在新型农村养老保险对农村土地转出的影响中发挥着中介作用,在新型农村合作医疗对农村土地流转影响中发挥的中介效应不明显。

体系化构造:美国保密基础设施立法及启示

数字技术高速发展态势下,国家保密法律制度需要树立符合时代特征的保密基础设施概念,充分考虑设置、维护、管理和销毁保密信息的端点、系统环境、人员的安全及相应的能力,以积极应对网络信息技术运用带来的环境变化和挑战。第二次世界大战后美国保密立法历程表明,美国通过法律法规推动保密基础设施的现代化和改革,逐步完成了系统架构下的涉密信息安全保障;而立法后紧跟的标准、手册等规范文件对贯彻实施其保密基础设施法律法规也起到了非常重要的作用。美国保密基础设施立法一直以国家安全战略为遵循,并不断加强与企业合作,如今则更加重视与网络安全的衔接。研究美国保密基础设施立法现状与趋势,为中国从立法理念、规范内容和形式等方面完善保密法律制度提供了新思路。

考虑信息泄露影响的光纤传感网络传输数据安全导入方法

为了提高对光纤传感网络传输数据安全传输能力,提出基于信息泄漏加密传输的光纤传感网络传输数据安全导入方法。采用离散混沌时间序列同步调制方法实现对光纤传感网络传输数据导入过程中调制编码处理,根据混沌随机编码特性实现对光纤传感网络传输数据过程中的同步输出稳定性调节和自主随机编码,构建光纤传感网络信息传输泄漏抑制的加密密钥,通过Logistics映射实现对光纤传感网络传输数据导入过程中的信息泄漏加密重传,根据光纤传感网络传输数据的混合敏感密钥表征和算术编码,实现信息泄漏控制和数据安全导入。实验结果表明,采用该方法进行光纤传感网络传输数据导入的加密性能较好,其光纤传感网络传输数据已加密比特序列的识别率为98%,误码率仅为2.7∗10-9%,抗泄漏能力达到了0.970,并且导入后的数据完整度达到了0.996,说明该方法具备了较强的加密效果、抗泄漏能力,实现数据的安全导入和加密传输。

农地流转对土地生态安全的影响研究进展

综述了土地生态安全领域研究进展及农地流转对土地生态安全的影响,总结了农地流转领域的相关研究,分析了新时代农业经营主体多元化背景下,土地利用中出现的新情况、新问题。针对当前农地流转生态风险认知不足、土地生态安全系统性评估方法体系有待完善、适应经营权流转的土地生态安全调控机制尚不健全等现实问题,提出进一步探索农业经营主体多元化对土地生态安全的影响机制,发展土地生态安全评估方法,建立从源头调控的土地生态安全调控机制,以满足新形势下乡村振兴中生态振兴对农地持续利用的精细化管理需求。

安检模式对铁路客站换乘地铁效率的影响

随着新技术涌现和运用,铁路车站客流集散过程中的安检模式对于车站区域步行换乘效率的影响及其空间设计策略,正受到越来越多的关注。运用“MassMotion”软件对出站人流进行模拟,比较了采用“人脸识别无感出站”和“轨道交通安检互认”技术前后,对于不同空间节点人流出站情况的非均质影响及交互效应,并基于上述结果建立了出站空间人员压力速查表,为铁路车站前期设计评估提供参考。

全面认识产业转移的新特征新模式——基于开放视角下的事实与分析

当前,全球产业链正向本地化、区域化、多元化、绿色化和数字化方向加速重构与调整。在此背景下,美欧等国家和地区陆续推出一系列政策措施,加速产业转移步伐,直接影响到我国的产业链供应链安全稳定。对此,文章利用fDi Markets、UN Comtrade等多个数据库,基于开放视角从来华投资、对外直接投资与中间品贸易三个关键维度对我国产业转移的理论与现状进行深入剖析,并归纳出当前产业转移的四种典型模式,进而在“分类研判”基础上提出“精准施策”的方案。研究发现:第一,在来华投资方面,尚未表现出大规模产业转移,法国等欧洲国家对华投资率先增长,但需警惕美日韩等地区以及电子元件、半导体和汽车设备等产业链较长行业的来华外资下降趋势。第二,在对外投资方面,总体呈现出稳中有进的态势,其中对墨西哥以及共建“一带一路”国家的投资增势最为突出,对电子元件、金属制品、汽车设备等高端制造行业以及矿产资源行业的投资也表现出了持续向好的态势。第三,在中间品贸易方面,近年来我国中间品出口在全球市场中的份额显著提升,其中对越南、印度和泰国等地区的出口比重大幅提高,高技术产品的出口增势也尤为突出。在此基础上,我们进一步归纳提出当前产业转移的四种主要模式:地缘政治驱动型、生产成本驱动型、产业链布局驱动型以及国际合作驱动型。最后,根据不同产业转移模式以及当前的产业转移新特征,提出相应的对策建议,为确保我国产业链供应链韧性与安全提供有益的支撑。

数据跨境双轨制下个人信息出境监管豁免制度的适用与完善

数据跨境新规确立了个人信息出境监管豁免制度,既豁免了申报数据出境安全评估,也豁免了订立个人信息出境标准合同、通过个人信息保护认证。但从我国数据跨境管理双轨制体系来看,这些豁免规则在理解适用上仍存在一系列困惑:符合场景豁免的个人信息是否必然豁免安全评估,一定数量个人信息为何可以豁免同等保护要求出境,过境个人信息豁免、负面清单外豁免的合理限度何在,实践需要与安全关切双重压力下应如何完善豁免。破解这些困惑,就应该明确特定豁免只是豁免保护个人权益的监管机制,厘清个人信息与重要数据关系以明确豁免边界,系统把握过境个人信息豁免和负面清单外豁免,增强数据跨境制度协同性以缓解豁免规则压力。

基于区块链技术的Web服务器数据加密方法

为了提高Web服务器数据的安全性,文章提出了一种基于区块链技术的Web服务器数据加密方法。先进行Web服务器数据去重,以减少冗余数据,建立安全传输协议,通过智能合约、生成和分发密钥实现数据的加密传输,确保数据在传输过程中不被未经授权的第三方截获或篡改。利用区块链技术加密访问控制,保障数据的安全访问,实现数据的加密。实验结果表明,该方法的安全系数始终保持在0.98以上,证明了该加密方法的可靠性。

移动互联网背景下跨境数据转移的安全问题分析

随着移动互联网的快速发展和全球数据流动的日益频繁,跨境数据转移涉及的数据收集、存储、使用等环节面临着加密问题、终端安全问题、API安全问题等威胁。文中探讨了数据收集、存储、使用过程中的主要安全隐患,提出了设计跨境数据转移管理机制、建立跨境数据转移安全渠道等防护措施,旨在为相关从业人员提供指导建议,确保跨境数据流动的安全性和高效性,促进全球数字经济的发展。

基于部分信息的SLT-LT联合码防窃听方案设计

近年来,信息的安全传输备受人们关注,现有的物理层安全技术从信息论的角度出发,将物理层安全编码与传输信道的动态物理特性进行结合,实现信息的保密传输。作为一种纠删码,LT(Luby transform)码由于其编码随机性、码率不固定等特性,使得窃听者不能直接从泄露的编码符号中得到有用信息,只要合法用户在窃听者之前接收到足够数量的编码符号,便可实现信息的安全传输。而作为一种转移LT(Shifted LT,SLT)码,SLT码能高效恢复信息的同时具有更小的译码开销。因此,我们将SLT码应用于Wyner降阶窃听信道模型进行研究,提出一种基于部分信息转移的SLT-LT联合码防窃听方案,信源利用接收者已知的部分信息对度分布进行调整,并对信源符号进行SLT-LT码级联编码。由于窃听信道是合法信道的降阶信道,因此外在的窃听者截获到的消息符号是合法接收者的降阶版本,在相同时间内,合法接收者能够收到更多消息符号,随着编解码过程的不断进行,合法接收者的优势不断累积,能够优先完成解码,而度分布的调整以及级联编码方案使得编码符号的平均度进一步增大,窃听者难以完成解码,进一步降低了窃听者译出率;之后,对所提方案的编解码性能以及安全性进行理论分析,并通过实验仿真进行验证,仿真结果表明,与其他防窃听LT方案相比,本文所提方案仅增加少量的译码开销但具有更好的安全性能。

劳动力转移对粮食生产韧性的影响研究--基于中国粮食主产区的实证

粮食安全是“国之大者”,随着农业劳动力大量转移,粮食生产韧性是否受到影响及受到的影响有多大,已成为新时期的重要议题。基于中国粮食主产区2010-2022年省域面板数据,通过构建主产区粮食生产韧性的综合指标体系,首先使用熵权与变异系数综合赋权法对其进行测度,其次选用固定效应模型实证检验农业劳动力转移对粮食生产韧性影响的内在逻辑。研究发现:农业劳动力转移有助于主产区粮食生产韧性的提升,且对粮食生产韧性的促进效应在较长时间序列上均稳健成立。具体而言,农业劳动力转移每增加1%,主产区粮食生产韧性水平将会平均增加1.712 0%。研究还发现,北方和南方主产区农业劳动力转移影响粮食生产韧性水平存在明显异质性,北方主产区的提升作用更为显著。因此,进一步引导农业劳动力非农转移推动区域粮食生产韧性水平提升,是新时期保障我国粮食安全的有效途径。

农地流转如何影响农业机械化——基于1878个水稻种植户的实证分析

在农业农村现代化不断推进的背景下,利用1878份南方水稻种植户调查数据,运用规模经济、农业分工和交易成本理论,探讨农地流转对水稻种植户机械化水平及其模式的影响。研究发现,农地流转显著提升了农业机械化水平,并促使机械化模式发生转变。利用农户产权安全感知度作为农地流转的工具变量,克服模型内生性,结果仍然稳健。具体而言,农户转入土地面积每增加一个百分点,其水稻种植机械化作业面积将增加0.386个百分点。同时,农户转入土地后自置农机的概率上升,而雇佣机耕和机收服务的概率下降,致使农机社会化服务市场转型。异质性分析表明,土地细碎化程度越高则更可能降低农地流转对农业机械化的正向影响;同时,中青年农户相比老年农户的农业生产机械化程度更高。为进一步推动小农户向现代农业转型,加快我国农业农村现代化进程,还需要加强土地产权保护、促进农地流转。