Blockchain-Based Data Acquisition with Privacy Protection in UAV Cluster Network

The unmanned aerial vehicle(UAV)self-organizing network is composed of multiple UAVs with autonomous capabilities according to a certain structure and scale,which can quickly and accurately complete complex tasks such as path planning,situational awareness,and information transmission.Due to the openness of the network,the UAV cluster is more vulnerable to passive eavesdropping,active interference,and other attacks,which makes the system face serious security threats.This paper proposes a Blockchain-Based Data Acquisition(BDA)scheme with privacy protection to address the data privacy and identity authentication problems in the UAV-assisted data acquisition scenario.Each UAV cluster has an aggregate unmanned aerial vehicle(AGV)that can batch-verify the acquisition reports within its administrative domain.After successful verification,AGV adds its signcrypted ciphertext to the aggregation and uploads it to the blockchain for storage.There are two chains in the blockchain that store the public key information of registered entities and the aggregated reports,respectively.The security analysis shows that theBDAconstruction can protect the privacy and authenticity of acquisition data,and effectively resist a malicious key generation center and the public-key substitution attack.It also provides unforgeability to acquisition reports under the Elliptic Curve Discrete Logarithm Problem(ECDLP)assumption.The performance analysis demonstrates that compared with other schemes,the proposed BDA construction has lower computational complexity and is more suitable for the UAV cluster network with limited computing power and storage capacity.

大断面水工隧洞复合型偏压洞段施工技术

乌斯通沟水库项目溢洪洞为半明半暗、浅埋条件下的复合型偏压隧洞。为了保证复合型偏压隧洞安全、快速开挖,同时,减少溢洪洞出口边坡开挖工程量,降低工程投资,对乌斯通沟水库溢洪洞复合型偏压洞段采取一些相应的工程措施,为日后相类似的工程项目提供参考。

乌斯通沟水库导流洞HF抗冲耐磨混凝土施工技术

随着国内水工混凝土技术的日益更新发展,市场上存在多种类的混凝土外加剂,尤以抗冲耐磨剂品种众多繁杂。因HF混凝土技术及其HF专用外加剂已被甘肃巨才公司以16类和一类商品申请了以“HF”为主要字母的商标,所以在乌斯通沟导流洞HF混凝土施工中,必须使用该公司HF专用抗冲耐磨剂。通过工艺性试验、现场生产性试验,同时在施工过程中解决HF抗冲耐磨混凝土出现的大面积气泡孔、水化热高、黏稠、骨料下沉、泌水、泌浆等问题。通过总结、归纳过程中的施工经验,为日后其他项目使用HF抗冲耐磨混凝土提供施工经验。

南水北调刁河渡槽出口渗水处理加固措施

文章依托南水北调中线工程刁河渡槽出口渐变段加固施工为工程实例,分析出口渐变段结构渗水问题,并在此基础上提出渗水处理加固措施,即采用帷幕灌浆施工一次截断工艺处治渗水问题,在闸室段工作门槽上游布置双排水泥灌浆孔,双排孔轴线位于工作门槽中心线上游3.60 m,灌浆孔布置两排,分两序进行灌浆,根据目前现场施工情况,先施工裹头边坡帷幕灌浆,再进行出口闸孔帷幕灌浆,最后进行闸墩帷幕灌浆,并配合全封闭防渗透策略,以提升渗水整治效果。经处置后,南水北调刁河渡槽出口渗水问题被妥善解决,处理效果良好。

Green manuring relocates microbiomes in driving the soil functionality of nitrogen cycling to obtain preferable grain yields in thirty years

Fertilizers are widely used to produce more food, inevitably altering the diversity and composition of soil organisms. The role of soil biodiversity in controlling multiple ecosystem services remains unclear, especially after decades of fertilization. Here, we assess the contribution of the soil functionalities of carbon(C), nitrogen(N), and phosphorus(P) cycling to crop production and explore how soil organisms control these functionalities in a 33-year field fertilization experiment. The long-term application of green manure or cow manure produced wheat yields equivalent to those obtained with chemical N, with the former providing higher soil functions and allowing the functionality of N cycling(especially soil N mineralization and biological N fixation) to control wheat production. The keystone phylotypes within the global network rather than the overall microbial community dominated the soil multifunctionality and functionality of C,N, and P cycling across the soil profile(0–100 cm). We further confirmed that these keystone phylotypes consisted of many metabolic pathways of nutrient cycling and essential microbes involved in organic C mineralization, N_(2)O release, and biological N fixation. The chemical N, green manure, and cow manure resulted in the highest abundances of amoB, nifH, and GH48 genes and Nitrosomonadaceae,Azospirillaceae, and Sphingomonadaceae within the keystone phylotypes, and these microbes were significantly and positively correlated with N_(2)O release, N fixation, and organic C mineralization, respectively. Moreover, our results demonstrated that organic fertilization increased the effects of the network size and keystone phylotypes on the subsoil functions by facilitating the migration of soil microorganisms across the soil profiles and green manure with the highest migration rates. This study highlights the importance of the functionality of N cycling in controlling crop production and keystone phylotypes in regulating soil functions, and provides selectable fertilization strategies for maintaining crop production and soil functions across soil profiles in agricultural ecosystems.

Enhancement of critical-sized bone defect regeneration by magnesium oxide-reinforced 3D scaffold with improved osteogenic and angiogenic properties

The healing of critical-sized bone defects(CSD)remains a challenge in orthopedic medicine.In recent years,scaffolds with sophisticated microstructures fabricated by the emerging three-dimensional(3D)printing technology have lighted up the treatment of the CSD due to the elaborate microenvironments and support they may build.Here,we established a magnesium oxide-reinforced 3D-printed biocompos-ite scaffold to investigate the effect of magnesium-enriched 3D microenvironment on CSD repairing.The composite was prepared using a biodegradable polymer matrix,polycaprolactone(PCL),and the disper-sion phase,magnesium oxide(MgO).With the appropriate surface treatment by saline coupling agent,the MgO dispersed homogeneously in the polymer matrix,leading to enhanced mechanical performance and steady release of magnesium ion(Mg^(2+))for superior cytocompatibility,higher cell viability,advanced osteogenic differentiation,and cell mineralization capabilities in comparison with the pure PCL.The in-vivo femoral implantation and critical-sized cranial bone defect studies demonstrated the importance of the 3D magnesium microenvironment,as a scaffold that released appropriate Mg^(2+) exhibited remarkably increased bone volume,enhanced angiogenesis,and almost recovered CSD after 8-week implantation.Overall,this study suggests that the magnesium-enriched 3D scaffold is a potential candidate for the treatment of CSD in a cell-free therapeutic approach.