Research and Design of a Routing Protocol in Large-Scale Wireless Sensor Networks

无线传感器网络，作为全球未来十大技术之一，集成了传感器技术、嵌入式计算技术、分布式信息处理和自组织网技术，可实时感知、采集、处理、传输网络分布区域内的各种信息数据，在军事国防、生物医疗、环境监测、抢险救灾、防恐反恐、危险区域远程控制等领域具有十分广阔的应用前景。 本文研究分析了无线传感器网络的已有路由协议，并针对大规模的无线传感器网络设计了一种树状路由协议，它根据节点地址信息来形成路由，从而简化了复杂繁冗的路由表查找和维护，节省了不必要的开销，提高了路由效率，实现了快速有效的数据传输。 为支持此路由协议本文提出了一种自适应动态地址分配算——ADAR（AdaptiveDynamicAddre...As one of the ten high technologies in the future, wireless sensor network, which is the integration of micro-sensors, embedded computing, modern network and Ad Hoc technologies, can apperceive, collect, process and transmit various information data within the region. It can be used in military defense, biomedical, environmental monitoring, disaster relief, counter-terrorism, remote control of haz...学位：工学硕士院系专业：信息科学与技术学院通信工程系_通信与信息系统学号：2332007115216

Transient analysis of idle time in VANETs using Markov-reward models

International audienceThe development of analytical models to analyze thebehavior of vehicular ad hoc networks (VANETs) is a challengingaim. Adaptive methods are suitable for many algorithms (e.g.choice of forwarding paths, dynamic resource allocation, channelcontrol congestion) and services (e.g. provision of multimediaservices, message dissemination). These adaptive algorithms helpthe network to maintain a desired performance level. However,this is a difficult goal to achieve, especially in VANETs due to fastposition changes of the VANET nodes. Adaptive decisions shouldbe taken according to the current conditions of the VANET.Therefore, evaluation of transient measures is required for thecharacterization of VANETs. In the literature, different worksaddress the characterization and measurement of the idle (orbusy) time to be used in different proposals to attain a moreefficient usage of wireless network. The present work focuseson the idle time of the link between two VANET nodes, whichwe denote as Tidle. Specifically, we have developed an analyticalmodel based on a straightforward Markov reward chain (MRC)to obtain transient measurements of Tidle. Numerical results fromthe analytical model fit well with simulation results

Transient analysis of idle time in VANETs using Markov-reward models

The development of analytical models to analyze the behavior of vehicular ad hoc networks (VANETs) is a challenging aim. Adaptive methods are suitable for many algorithms (e.g., choice of forwarding paths, dynamic resource allocation, channel control congestion) and services (e.g., provision of multimedia services, message dissemination). These adaptive algorithms help the network to maintain a desired performance level. However, this is a difficult goal to achieve, especially in VANETs due to fast position changes of the VANET nodes. Adaptive decisions should be taken according to the current conditions of the VANET. Therefore, evaluation of transient measures is required for the characterization of VANETs. In the literature, different works address the characterization and measurement of the idle (or busy) time to be used in different proposals to attain a more efficient usage of wireless network. This paper focuses on the idle time of the link between two VANET nodes, which we denote as Tidle. Specifically, we have developed an analytical model based on a straightforward Markov reward chain to obtain transient measurements of Tidle. Numerical results from the analytical model fit well with simulation results.Peer Reviewe

Vibrational Coupling of Nearest Neighbors in 1-D Spin Crossover Polymers of Rigid Bridging Ligands. A Nuclear Inelastic Scattering and DFT Study

The nuclear inelastic scattering signatures of the low-spin centers of the methanosulphonate, tosylate, and perchlorate salts of the spin crossover polymer ([Fe(II)(4-amino-1,2,4-triazole)3]2+)n have been compared for the low-spin phase, for the mixed high-spin and low-spin phases, as well as for Zn(II) diluted samples. Within this series a change in the vibrational pattern in the 320–500 cm−1 region is observed. Significant shifts and decreasing intensity of bands at ~320 cm−1 and bands over 400 cm−1 are observed as the molar fraction of the low-spin (LS) centers decrease. Density functional theory calculations using Gaussian09 (B3LYP/CEP-31G) for pentameric, heptameric, and nonameric model molecules yielded the normal modes of several spin isomers: these include the all high-spin (HS) and the all low-spin (LS) configuration but also mixtures of LS and HS centers, with a special focus on those with LS centers in a HS matrix and vice versa. The calculations reproduce the observed spectral changes and show that they are caused by strain extorted on a LS Fe(II) center by its HS neighbors due to the rigid character of the bridging aminotriazole ligand. Additionally, the normal mode analysis of several spin isomers points towards a coupling of the vibrations of the iron centers of the same spin: the metal-ligand stretching modes of the all LS and the all HS spin isomers reveal a collective character: all centers of the same spin are involved in characteristic normal modes. For the isomers containing both LS and HS centers, the vibrational behavior corresponds to two different subsets (sublattices) the vibrational modes of which are not coupled. Finally, the calculation of nuclear inelastic scattering data of spin isomers containing a ca. 1:1 mixture of HS and LS Fe(II) points towards the formation of blocks of the same spin during the spin transition, rather than to alternate structures with a HS-LS-HS-LS-HS motif

Site-selective detection of vibrational modes of an iron atom in a trinuclear complex

Nuclear inelastic scattering (NIS) experiments on the trinuclear complex [$^{57}Fe{L-N_{4}(CH_{2}Fc)_{2}} (CH_{3}CN)_{2}](ClO_{4})_{2}$ have been performed. The octahedral iron ion in the complex was labelled with $^{57}$Fe and thereby exclusively the vibrational modes of this iron ion have been detected with NIS. The analysis of nuclear forward scattering (NFS) data yields a ferrous low-spin state for the $^{57}$Fe labelled iron ion. The simulation of the partial density of states (pDOS) for the octahedral low-spin iron(II) ion of the complex by density functional theory (DFT) calculations is in excellent agreement with the experimental pDOS of the complex determined from the NIS data obtained at 80 K. Thereby it was possible to assign almost each of the experimentally observed NIS bands to the corresponding molecular vibrational modes

Nuclear inelastic scattering and density functional theory studies of a one-dimensional spin crossover [Fe(1,2,4−triazole)2(1,2,4−triazolato)](BF4)\mathrm{[Fe(1,2,4-triazole)_{2}(1,2,4-triazolato)](BF_{4})} molecular chain

Nuclear inelastic scattering (NIS) experiments have been performed in order to study the vibrational dynamics of the low- and high-spin states of the polynuclear 1D spin crossover compound [Fe(1,2,4-triazole)$_2$(1,2,4-triazolato)](BF$_4$) (1). Density functional theory (DFT) calculations using the functional B3LYP* and the basis set CEP-31G for heptameric and nonameric models of the compound yielded the normal vibrations and electronic energies for high-spin and low-spin isomers of three models differing in the distribution of anionic trz$^−$ ligands and BF$_{4}^−$ anions. On the basis of the obtained energies a structural model with a centrosymmetric Fe(trzH)$_4$(trz$^−$)$_2$ coordination core of the mononuclear unit of the chain is proposed. The obtained distribution of the BF$_{4}-$ counteranions in the proposed structure is similar to that obtained on the basis of X-ray powder diffraction studies by Grossjean et al. (Eur. J. Inorg. Chem., 2013, 796). The NIS data of the system diluted to 10% Fe(II) content in a 90% Zn(II) matrix (compound (2)) show a characteristic change of the spectral pattern of the low-spin centres, compared to the low-spin phase of the parent Fe(II) complex (1). DFT calculations reveal that this is caused by a change of the structure of the neighbours of the low-spin centres. The spectral pattern of the high-spin centres in (2) is within a good approximation identical to that of the high-spin Fe(II) isomer of (1). The inspection of the molecular orbitals of the monomeric model systems of [Fe(trzH)$_4$(trz$^−$)$_2$] and [Fe(trzH)$_6$], together with calculations of spin transition energies, point towards the importance of an electrostatic effect caused by the negatively charged ligands. This results in the stabilisation of the low-spin state of the complex containing the anionic ligand and shortening of the Fe–N(trz$^−$) compared to the Fe–N(trzH) bond in high-spin, but not in low-spin [Fe(trzH)$_4$(trz$^−$)$_2$]

Divergent Coordination Chemistry: Parallel Synthesis of [2×2] Iron(II) Grid-Complex Tauto-Conformers

The coordination of iron(II) ions by a homoditopic ligand L with two tridentate chelates leads to the tautomerism-driven emergence of complexity, with isomeric tetramers and trimers as the coordination products. The structures of the two dominant [Fe$^{II}_4$L$_4$]$^{8+}$ complexes were determined by X-ray diffraction, and the distinctness of the products was confirmed by ion-mobility mass spectrometry. Moreover, these two isomers display contrasting magnetic properties (Fe$^{II}$ spin crossover vs. a blocked Fe$^{II}$ high-spin state). These results demonstrate how the coordination of a metal ion to a ligand that can undergo tautomerization can increase, at a higher hierarchical level, complexity, here expressed by the formation of isomeric molecular assemblies with distinct physical properties. Such results are of importance for improving our understanding of the emergence of complexity in chemistry and biology

Site-selective detection of vibrational modes of an iron atom in a trinuclear complex

Nuclear inelastic scattering (NIS) experiments on the trinuclear complex [$^{57}Fe{L-N_{4}(CH_{2}Fc)_{2}} (CH_{3}CN)_{2}](ClO_{4})_{2}$ have been performed. The octahedral iron ion in the complex was labelled with $^{57}$Fe and thereby exclusively the vibrational modes of this iron ion have been detected with NIS. The analysis of nuclear forward scattering (NFS) data yields a ferrous low-spin state for the $^{57}$Fe labelled iron ion. The simulation of the partial density of states (pDOS) for the octahedral low-spin iron(II) ion of the complex by density functional theory (DFT) calculations is in excellent agreement with the experimental pDOS of the complex determined from the NIS data obtained at 80 K. Thereby it was possible to assign almost each of the experimentally observed NIS bands to the corresponding molecular vibrational modes