本文从工程技术人才培养的角度,结合"数据库系统原理"课程培养目标,分析了在教学中普遍存在的问题,提出了针对该课程线上线下进行混合式教学的新模式,详细阐述了课前、课中和课后分别进行在线学习、项目驱动教学、任务驱动和项目实践学习等,形成一个有机渐进式的教学过程,并通过优化课程实验内容和改进评价体系,实现"以本为本"和工程认证中成果导向教育的目标.

为了降低IEEE 802.15.4MAC层数据帧丢包率,在分析丢包率的原因基础上,提出了一种基于Markov链的信道竞争机制模型.通过对网络发送、退避和信道检测状态的稳态概率进行数学推导,研究了信道碰撞和数据帧的丢包率分析式,研究了参数数据包到达速率、节点数量、误码率、后退指数、后退等待次数对碰撞概率和丢包率的影响.实验结果表明,与节点无休眠态的IEEE 802.15.4网络相比,节点丢包率平均降低了23.7％,模型较好地描述了提出的MAC层信道访问机制,合理的网络参数设置能够优化数据帧丢包率,研究结果对无线传感网的应用提供了可靠传输优化参考.

In wireless sensor networks,malicious nodes will tamper or falsify the data to affect the final fusion results.To solve this problem,an effective method for detecting malicious nodes based on secure data aggregation in clustered wireless sensor networks is proposed,which is able to quantify the uncertainty of node's monitoring data and judge whether the node is credible or not.Besides,the specific malicious node's detection and processing method is introduced.Simulation results show that the model is capable of detecting malicious nodes effectively,and achieving high detection rate and low false detection rate.

分析了当前高校物联网工程专业课程体系建设存在的问题,基于CDIO一体化课程体系的构建思想,针对如何培养真正适用于物联网产业的创新复合型人才提出了面向创新能力培养的课程体系建设思路,讨论了物联网专业课程体系建设和改革的关键内容,并给出了详细的能力培养教学方案,以切实提高学生的综合实力.

针对基于隐藏终端的802.15.4网络数据丢包问题,提出了一种时隙CSMA/CA算法的数学模型.基于模型推导建立数据丢包概率的数学模型,并研究隐藏终端对数据丢包现象的影响.然后研究不同网络参数如隐藏终端数、 λ、N、minBE和NB对数据丢包的影响.实验表明:通过合理的参数配置能够改善网络丢包问题,且相对于不考虑隐藏终端的情形,隐藏终端导致的丢包问题更加严重(高出25.2%).实验结果说明提出的算法模型较好的描述了802.15.4网络实际运行特征.

In order to improve the data transmission reliability in Media Access Control (MAC) layer for 802.15.4 network,this paper proposes a Markov chain model of node working process based on unsaturated state,and the derivation calculation is carried out for the steady-state probability of the node status.The two factors affecting the transmission reliability in MAC layer are researched:the failure of node access channel and the limit of maximum retransmission times,and the analytical formula of reliability performance is derived.The influence of the parameters including minBE,NB and λ and two factors on the reliability is analyzed,and the effects of the two kinds of factors on the reliability performance are compared.Experimental results show that compared with the node working model without sleep mechanism,the proposed model can greatly reduce channel conflict,and improve network reliability.

In order to decrease the frame packet lost rate in 802 . 15 . 4 network , this paper analyzed the packet lost rate based on the retransmission mechanism , proposed the mathematical model for the working process of network node in MAC layer , and derived the steady-state probability of the main state . Afterwards , this paper carried out the mathematical analysis for the retransmission probability and the packet lost rate . Finally , the effect of MAC layer parameters minBE , NB and network environment parameter λ、N、BER on the retransmission probability and the packet loss rate was compared through the experimental analysis . Experimental re-sults show that the node packet loss rate is reduced by 88 . 9%, compared with the data transmission performance without retrans-mission mechanism . And the model could accurately reflect the node data transmission characteristics . Furthermore , equilibrium pa-rameter deployment could effectively improve the data transmission success rate , and theoretical research could provide the reference for 802 . 15 . 4 network standard .

Aiming at the optimization problems of the data packet average service time of 802.15.4 MAC layer,this paper proposed a conversion mechanism of node state based on super frame structure,and analyzed the definition of the data packet average service time.After that,it derived the steady-state probability of the main state and the formula of the data packet aver-age service time by establishing the model of Markov chain on the state of the node.At last,this paper researched the influ-ence of the protocol parameters such as NB,BE,SO to the data packet service time of the steady-state probability.The research results show that,the data packet average service time is reduced by 2.3%,compared with other dormant node models.The model describes the working characteristics of 802.15.4 network nodes very well.The balanced configuration of protocol pa-rameters can improve the packet transmission performance.And the model can provide the reference for raising the real-time performance of the network.

从"数据库系统原理"在应用型本科计算机专业教学中的地位和课程特点出发,分析了我校当前在该课程教学中存在的问题,提出了改进教学质量的方法,包括:优化整合教学内容,设置分级课程教学模块,促进人才的多元化培养;利用基于"软件工程"的思想,将理论和实践结合进行课堂教学;多元化的考核机制.通过实践表明,新的教学模式在提高学生的学习兴趣,增强他们的数据库分析与设计能力等方面取得了良好的效果,有效提高了教学质量.

针对LEACH协议中每轮产生的簇头个数为最佳簇头数的概率并不是最大,网络能量效率低的问题,提出了一种节点服从泊松分布的WSNs分簇协议能耗优化模型.考虑到一般选择多跳路由比单跳路由更节省能量,对多跳方式下的协议能耗和最优分簇数目的分析和建模,建立了节点泊松分布密度、最优分簇数目与能耗的关系.理论分析和仿真实验表明:节点泊松分布密度影响最优分簇数目,而最优分簇情况下分簇能耗最优,所以适当调整节点分布密度,合理选取最优分簇数目,能够有效地改善WSNs分簇协议的能耗性能.

计算机专业作为一个以实践为主的专业，其学生培养不仅有理论教学，更重要的是注重实践教学，加强学生实践动手能力的培养，提高学生自我学习、分析问题、解决问题的能力。从建立学生团队、积极参与专业技能比赛的角度，探讨了基于学生团队培养的计算机专业实践教学模式改革，旨在为经济发展培养高质量的信息技术教育和开发人才。

Taking into account the data correlation between the adjacent nodes of the same region,an intra-cluster data aggregation mechanism based on the max-min approach degree principle was presented.The data from the noncluster head nodes should be firstly checked in the cluster head to judge whether the data can be adopted according to the confidence interval and then will be aggregated in the next process.The experimental results showed that this method can effectively solve the problem that the collected data are inconsistent in the credibility degree,and can extend the network life.

In order to ensure the data privacy of the sensor nodes and improve the network life cycle,this paper proposes a low energy-consuming private data aggregation method based on unequal clustering(UCDA).Firstly,the tentative cluster heads construct clusters of unequal sizes by using uneven competition ranges according to the distance to Base station.Then,the fragment recombination technology is adopted.To reduce the communication overhead and obtain the data privacy.the node in the overlap area of different clusters slice its private data into pieces,and then it send to the cluster heads for mixing in the next process.Simulation results show that UCDA can preserve data privacy,get accurate data aggregation results and cost less communication and computation overhead when compared with the SMART algorithm.

Aiming at energy consumption optimisation of 6LoWPAN network,in this paper we propose a channel access mechanism in which the packet arrival rate subjects to Poisson distribution: in active period of the superframe,those nodes without data transmission or unable to send data temporarily will transfer to dormant period for energy saving,then we set up a Markov chain model for this mechanism.Based on the model,we carry out mathematical analysis on the steady state probability of node dormant status,the service time of data packets and the average energy consumption of the node,and study the impact of protocol parameters such as λ and BO on network performance.Mathematical analyses demonstrate that the improved model describes channel competitive process of 6LoWPAN network well and reduces the average energy consumption of node effectively.

The residual energy of the nodes are not paid great attention in the process of the cluster-head election in LEACH,and the whole life cycle of the network will be reduced while the nodes with low energy become cluster heads.In this paper,we propose the idea of classification according to the residual energy of the nodes for the sake of that the node with higher level are more likely to be cluster-head.In addition,for the noncluster head nodes,they may receive the messages from multiple candidate cluster heads and choose to join the cluster according to the comprehensive evaluation of residual energy and distance.In order to make the energy consumption more balanced,the clusterheads send the data to the sink in the manner of multi-hop transmission,and use unequal clustering mechanism to avoid the situation where the nodes near the sink deplete their energy much faster than distant nodes.The simulation results show that our algorithm can achieve load balancing and prolong the life cycle of the network effectively.

To optimize the performance of throughput of 6LoWPAN,a mechanism of channel competitive access based on sleep periods in super frame was proposed.Then a Markov chain model was established for MAC of 6LoWPAN and the mathematical derivation for the model was carried out.Furthermore,the numerical analysis of the channel throughput based on unsaturated traffic was carried out.And the impact of protocol parameters such as λ,NB and minBE to performance of throughput was researched.Finally,it is showed by the theoretical analysis the model can describe the mechanism of channel competitive access well and analyze the dynamic changes of the throughput accurately based on sleep mechanism.

In order to improve the performance of energy consumption for 6LoWPAN network,a channel contention mechanism based on superframe sleep period was proposed.Then a Markov chain model was established for the mechanism.Based on this model,the mathematical analysis on the steady-state probability of sending state,channel conflict probability and node average energy consumption was performed,and moreover the influence of the protocol parameters λ、minBE and NB on the network performance such as energy consumption was also analyzed.Finally,it is showed by the theoretical analysis that our model describes the MAC protocol of 6LoWPAN very well.The new mechanism reduces the network energy consumption,and the performance of protocol is improved.

Aiming at the problems of the lowly energy efficiency in LEACH protocol,we proposed an energy consumption mode of WSNs clustering protocol in the condition that sensor nodes followed the Poisson distribution.Firstly,we inferred the power consumption of cluster head,node and the clustering protocol.Secondly,the optimization analysis of cluster numbers based on the power consumption was carried out,and the network lifetime was calculated.Finally,we analyzed the network performance which was impacted by sensor nodes Poisson distribution density.The theoretical analysis and simulation results show that both the energy performance and the network lifetime of WSNs clustering protocol could be improved effectively by increasing the node Poisson distribution density suitably and choose the optimal cluster numbers.

针对LEACH协议中节点网络能量效率低的问题,建立了分簇协议的能耗模型;基于对簇首竞选能耗和不同节点能耗差的分析,提出了一种基于非竞争式的WSNs簇首轮换方法:在每一个轮转周期的第一轮中竞选一次簇首,其余轮中采取固定轮转的方法依次让其它节点充当簇首;同时合理设置每轮中的数据收集次数,以便有效降低网络簇首竞选能耗;理论分析和仿真实验表明:改进的分簇算法能够有效地改善WSNs分簇协议的总能耗性能。

Prolonging the life time of the networks and reducing the energy consumption of the nodes are the central topic for research on WSNs routing protocols.Aiming at the problem of unbalanced energy consumption of nodes and low energy utilization because of irrationality of choosing cluster head and the nodes only consider their own communication cost in the formation of the cluster in LEACH,a lower power consumption clustering protocols based on the multi-weight is proposed,which take into consideration many factors such as the current energy,the times of being a selected cluster-head and the number of cluster-head in current network.Finally,the simulation results showed that the improved procotol can decrease energy consumption of nodes better and prolong the life tim e of the networks.