基于物联网的农场信息接收与发布平台设计与实现

为了远程实时监测农场无线传感器网络的环境数据,使用B/S、C/S混合架构设计了农场信息接收与发布平台。系统由C/S服务器、数据库、B/S服务器、客户端浏览器组成。介绍了Socket数据通信、用户控制模块、节点分布显示模块的实现。重点阐述了平台数据异常检测、数据实时发布等关键技术;功能验证表明：平台通过友好的人机互交界面准确呈现农场实时环境数据,并具备管理员远程控制能力。信息发布与接收平台满足远程实时监控的要求。具有一定使用价值。     

Density functional study of uranyl （VI） amidoxime complexes

Uranyl (Ⅵ) amidoxime complexes are investigated using relativistic density functional theory. The equilibrium structures, bond orders, and Mulliken populations of the complexes have been systematically investigated under a generalized gradient approximation (GGA). Comparison of (acet) uranyl amidoxime complexes ([UO 2 (AO) n ] 2 n , 1≤ n ≤4) with available experimental data shows an excellent agreement. In addition, the U-O(1), U-O(3), C(1)-N(2), and C(3)-N(4) bond lengths of [UO 2 (CH 3 AO) 4 ] 2 are longer than experimental data by about 0.088, 0.05, 0.1, and 0.056 A. The angles of N(3)-O(3)-U, O(2)-N(1)-C(1), N(3)-C(3)-N(4), N(4)-C(3)-C(4), and C(4)-C(3)-N(3) are different from each other, which is due to existing interaction between oxygen in uranyl and hydrogen in amino group. This interaction is found to be intra-molecular hydrogen bond. Studies on the bond orders, Mulliken charges, and Mulliken populations demonstrate that uranyl oxo group functions as hydrogen-bond acceptors and H atoms in ligands act as hydrogen-bond donors forming hydrogen bonds within the complex.     

Broadly tunable mid-infrared VECSEL for multiple components hydrocarbon gas sensing

A new sensing platform to simultaneously identify and quantify volatile C1 to C4 alkanes in multi-component gas mixtures is presented. This setup is based on an optically pumped, broadly tunable mid-infrared vertical-external-cavity surface-emitting laser (VECSEL) developed for gas detection. The lead-chalcogenide VECSEL is the key component of the presented optical sensor. The potential of the proposed sensing setup is illustrated by experimental absorption spectra obtained from various mixtures of volatile hydrocarbons and water vapor. The sensor has a sub-ppm limit of detection for each targeted alkane in a hydrocarbon gas mixture even in the presence of a high water vapor content.     

基于CMOS图像传感器的可见光遥感相机原型系统设计

遥感器是遥感技术应用的基础设备,它决定了遥感系统的成像质量。介绍了光电传感器在可见光遥感中的应用,阐述了光电遥感器的结构与关键技术,提出了CMOS数字传感器在遥感领域应用中所具有的优势,设计并实现了基于CMOS传感器的光电成像原型系统。结果表明,遥感相机的图像获取、数据存储的基本功能为CMOS在可见光遥感应用中的相关问题提供了研究平台和技术储备。     

Applicability of chemical derivatization – X-ray photoelectron spectroscopy (CD–XPS) to the characterization of complex matrices: case of electrosynthesized polypyrroles

Problems arising in the application of XPS coupled with derivatization reactions (CD-XPS) to the characterization of complex matrices are stressed by considering the case of polypyrroles electrosynthesized from aqueous solution. In these materials oxygen– and nitrogen–carbon functionalities are contemporaneously present, as well as acidic, basic, charged and reducible groups. The derivatizing agents titanium di-isopropoxide-bis(2,4-pentanedionate) (TAA), trifluoroethanol (TFE) and pentafluorophenylhydrazine (PFPH) were used to label the C–OH, COOH and CO groups, respectively, in the pristine (PPY) and in the overoxidized (PPYox) polymer. The case shows that, when real samples are analysed, only the correlation among the information present in all the available spectra can supply the key to the interpretation of CD-XPS data, such as the actual stoichiometry and secondary effects. In particular, it is showed that PFPH cannot be used as a reliable derivatizing agent for CO groups in PPYox, due to the competition of a side reaction (already reported for hydrazines) occurring on this particular substrate. This effect may be disregarded if a thorough control of the stoichiometry is not performed.     

Conformations and enthalpies of formation of methylenecyclohexane, 1,4‐dimethylenecyclohexane,cyclohexanone, 4‐methylenecyclohexanone, 1,4‐cyclohexanedione,and their mono‐ and dioxa derivatives by G3(MP2)//B3LYP calculations

A computational study of the stable conformations and gas‐phase enthalpies of formation at 25 °C of the title compounds has been carried out by G3(MP2)//B3LYP calculations. The work stems from our early observations on the thermodynamic and NMR spectroscopic properties of 2‐methylenetetrahydropyran and related compounds suggesting a dominating chair conformation, with poor p–π overlap in the ? O? C?C moiety, for these compounds. Besides computational verification of the chair conformation of 2‐methylenetetrahydropyran, the work was extended to find out the stable conformations of a number of other related compounds and to evaluate the relative stabilities of the various conformers. Another important goal of the work was the estimation of the gas‐phase enthalpies of formation of the present compounds, for which such literature data are scarce. A significant error in the literature value of the enthalpy of formation of methylenecyclohexane was found. Finally, the relative enthalpy levels of the isomeric compounds of this work are discussed. The high thermodynamic stability of the compounds containing an ester functional group, ? O? C?O, relative to the stability of isomeric compounds with an ? O? C?C moiety in place of the ester function, is demonstrated. Copyright © 2009 John Wiley & Sons, Ltd.     

天体演化过程中CNO核子辐射俘获反应

C和N核的质子辐射俘获反应对恒星平稳H燃烧阶段的能量产生和元素核合成起重要作用, C, N和O 核的中子辐射俘获是原初核合成和AGB星核合成的关键反应, 精确测定它们天体物理反应率有重要意义。 除13N(p, γ)14O和16N(n, γ)17N等不稳定核的核子辐射俘获反应外, 国际上已完成了其中若干反应的直接测量工作。 但12C(p, γ)13N, 13C(p, γ)14N和15N(p, γ)16O等CNO循环关键反应的实验测量还没有达到天体物理感兴趣的能区。 13C(n, γ)14C,15N(n, γ)16N和18O(n, γ)19O等中子辐射俘获反应测量的能量跨度较大, 截面仍存在较大的不确定性。 介绍了这些反应的研究进展, 并讨论了间接测量这些反应的方法和可行性。 The proton radiative capture reactions of C and N nuclei are important for the energy production and nucleosynthesis in the CNO cycle, and the neutron radiative capture reactions of C, N and O nuclei are key reactions for the inhomogeneous Big Bang nucleosynthesis as well as for the neutron induced CNO cycle in AGB stars. So far, most of these reactions have been measured except some reactions of the unstable nuclei, such as 13N(p, γ)14O and 16N(n, γ)17N. While the direct measured reactions, such as the  12C(p, γ)13N, 13C(p, γ)14N and 15N(p, γ)16O key reactions in CNO cycle, have not reached down to the stellar energies. In addition, the large uncertainties still exist in the measured neutron capture reactions such as 13C(n, γ)14C,15N(n, γ)16N and 18O(n, γ)19O. Thus it is significant to determine their astrophysical reaction rates via the indirect measurements. In this paper, the research status and feasibility of the indirect measurements for these reactions are discussed.     

Bonding analysis for NgMOH (Ng=Ar,Kr and Xe; M=Cu and Ag)

The structures and stabilities of a new class of species, noble-gas–coinage-metal hydroxides NgMOH (Ng =?Ar, Kr and Xe; M =?Cu and Ag), are investigated at the MP2 theoretical level. All species are found to be in Cs symmetry with an approximate linear Ng–M–O moiety. The noble-gas–coinage-metal bond lengths are in the range of the respective covalent and van der Waals limits, showing a different degree of approach to the former along the series Ar–Kr–Xe for Ng–Cu and Ng–Ag bonds, respectively. The dissociation energies of noble-gas–coinage-metal bonds are relatively large as compared to the van der Waals complexes. Besides the charge-induced dipole contribution, other effects –?higher-order charge-induction energies, dispersion interaction, etc., should be considered to explain the noble-gas–coinage-metal bonding mechanism. The present results suggest that the title species are stable enough to be prepared experimentally.     

Cold preservation of isolated hepatocytes in UW solution: experimental studies on the respiratory activity at 0 degrees C

To date, little attention has been paid to the role of the gas milieu in preservation solutions and its effect on cell viability. Dissolved O2 in the preservation media may be an important parameter to consider. In this study we polarographically measured the O2 concentration in air-equilibrated UW solution at 0 degrees C, as well as the respiratory activity of isolated hepatocytes cold-preserved in this solution up to 72 hours. To perform measurements at 0 degrees C, it was first necessary to characterize the sensor behavior at low temperatures. We verified that the sensor response is still linear at this temperature but the rate of response is significantly slower. The O2 solubility in UW-air solution at 0 degrees C was determined using a modified physical method and it was 410 microM O2, which, as expected, is lower than the solubility in water at the same temperature (453 microM O2). Isolated hepatocytes cold-stored in UW-air solution retained a measurable respiratory activity during a period of 72 hours. The O2 consumption rate was 0.48 +/- 0.13 nmol/O2/min/10(6) cells, which represents 1% of the control value at 36 degrees C (61.46 +/- 14.61 nmol/O2/min/10(6) cells). The respiratory activity and cell viability were well maintained during the preservation period. At present, preservation conditions need to be improved for cells to remain functionally active. Dissolved O2 may be required for energy re-synthesis but it also leads to an increment in reactive oxygen species. The O2 concentration in the preservation solution should be carefully controlled, reaching a compromise between cell requirement and toxicity.     

基于嵌入式的数字显微镜图像采集系统的研究

提出了一种在ARM9开发平台上构建数字显微镜图像采集系统的实现方案。通过CMOS图像采集模块把显微镜下物体的图像信息转换成数字信号,输入到S3C2410的开发平台,然后图像被显示到LCD液晶屏上或存储到SD卡上。系统通过相应的程序可以实现显微图像的采集、显示、存储等操作。实验结果表明,该系统采集的图像清晰,并且具有性能稳定、体积小、成本低等优点。     

Spectroscopy of CH<Subscript>4</Subscript> with a difference-frequency generation laser at 3.3 micron for atmospheric applications

The 3.25 micron spectral region is very suitable for the in situ sensing of CH₄ in the troposphere and the lower stratosphere with light-weight laser sensors. Several transitions of the strong fundamental ν ₃ band of CH₄ are revisited in this spectral region using an ultra-compact Difference-Frequency Generation (DFG) laser. Accurate intensities as well as self-broadening coefficients are reported for several manifolds that are particularly relevant to the monitoring of CH₄. The study is extended to over hundred transitions reachable over the tunability range of the laser. Moreover, this DFG laser is the light source of a new, highly-compact CH₄ laser spectrometer to be operated from weather balloon. The CH₄ laser sensor is described and preliminary flight results are reported.     

Co3O4掺杂SnO2体系的乙醇和丙酮气敏特性

通过研磨、涂浆和700 ℃ 烧结3 h的方法， 得到了一系列Co3O4掺杂的SnO2纳米颗粒厚膜． 发现在300 ℃ 的工作温度下复合膜对乙醇和丙酮表现了很好的气敏性质， 尤其是在摩尔比Co/Sn为5%时效果达到最好． 对1000 ppm的乙醇和丙酮的灵敏度分别为301和200，为没有Co掺杂时的SnO2时的7倍和5倍．同时，Co3O4的掺杂没有使得对H2的灵敏度有很大的提高，即提高了乙醇和丙酮对氢气的选择性．最后讨论了提高气敏性能的机制．     

Internal hydrogen bond,torsional motion,and molecular properties of 2-methoxyethylamine by microwave spectroscopy: Methyl barrier to internal rotation for 2-methoxyethanol

The microwave spectra of four substituted isotopic species of 2-methoxyethylamine (NH₂, NHD, NDH, ND₂) have been assigned. The molecule is found to exist in a gauche form with an intramolecular hydrogen bond of the NH?O type. The four possible sets of the amino hydrogen r_s corrdinates give different H?H distances, probably because the -NH₂ group is involved in large amplitude vibrations and because of changes in the heavy atom positions arising from the deuteration of the hydrogen bond. For the most abundant species many vibrational states have been analyzed and assigned to the two possible CO torsions in the molecule. A value V₃ = 3150 ± 50 cal/mol was found for the methyl torsional barrier and V₁ = 9 ± 3 kcal/mol for the other CO torsional barrier. A third set of observed vibrational satellites is probably assignable to the CC torsion. The determination of the dipole moment and of the quadrupole coupling constants gave values which were not in good agreement with those predicted from nonhydrogen bonded molecules. In addition a value V₃ = 3100 ± 100 cal/mol was calculated for the CH₃ torsional barrier in the related 2-methoxyethanol, using previous experimental data (Canad. J. Chem.50, 1149–1156 (1972)).     

Synthesis of hierarchical flower-like NiO and the influence of surfactant

The NiO nanoflowers were prepared by a facile surfactant assisted hydrothermal method using Ni(NO₃)₂–6H₂O or NiCl₂–6H₂O as precursor compound. The microstructure of the samples was characterized by SEM and XRD. The gas sensing properties of the NiO nanoflowers toward ethanol was also investigated. The results show that surfactant plays a key role in the synthesis of flower-like NiO. The NiO nanoflowers show excellent sensing performances to ethanol gas. This morphology holds substantial promise for applying NiO as a potential gas sensing material for future sensor application.     

EPR/FMR, FTIR, X-Ray and Raman Investigations of Fe-Doped SiCN Ceramics

SiCN magnetic ceramics doped with Fe ions were synthesized at different pyrolysis temperatures in the range from 600 to 1600°C. Several phases of ceramics were detected using the techniques of electron paramagnetic resonance/ferromagnetic resonance, Raman, Fourier-transform infrared and X-ray diffractometry, listed as follows: (a) transformation to the ceramic state from the polymer state, where the Fe ions are in the paramagnetic state, as the temperature is increased from 600 to 800°C; (b) formation of two different Fe species in the range of 950–1150°C: nanocrystalline particles in the ferromagnetic state and Fe ions incorporated into the free-carbon state in the superparamagnetic state; (c) diminution of the free-carbon content above 1150°C, and, as a consequence, diminution of the intensity of the broad Fe signal related to this phase; (d) appearance of a new Fe phase at about 1200°C; (e) disappearance of the ferromagnetic phase at about 1400°C; (f) disappearance of all Fe ions above 1530°C. The samples exhibiting superparamagnetic behavior are potentially useful in developing high-temperature magnetic sensor devices.     

Computational study on structures,thermochemical properties,and bond energies of disulfide oxygen (S–S–O)‐bridged CH3SSOH and CH3SS(=O)H and radicals

Cleavage of disulfide bonds is a common method used in linking peptides to proteins in biochemical reactions. The structures, internal rotor potentials, bond energies, and thermochemical properties (Δ_fH°, S°, and Cp(T)) of the S–S bridge molecules CH₃SSOH and CH₃SS(=O)H and the radicals CH₃SS?=O and C?H₂SSOH that correspond to H‐atom loss are determined by computational chemistry. Structure and thermochemical parameters (S° and Cp(T)) are determined using density functional Becke, three‐parameter, Lee–Yang–Parr (B3LYP)/6‐31++G (d, p), B3LYP/6‐311++G (3df, 2p). The enthalpies of formation for stable species are calculated using the total energies at B3LYP/6‐31++G (d, p), B3LYP/6‐311++G (3df, 2p), and the higher level composite CBS–QB3 levels with work reactions that are close to isodesmic in most cases. The enthalpies of formation for CH₃SSOH, CH₃SS(=O)H are ?38.3 and ?16.6 kcal mol^?1, respectively, where the difference is in enthalpy RSO–H versus RS(=O)–H bonding. The C–H bond energy of CH₃SSOH is 99.2 kcal mol^?1, and the O–H bond energy is weaker at 76.9 kcal mol^?1. Cleavage of the weak O–H bond in CH₃SSOH results in an electron rearrangement upon loss of the CH₃SSO–H hydrogen atom; the radical rearranges to form the more stable CH₃SS· = O radical structure. Cleavage of the C–H bond in CH₃SS(=O)H results in an unstable [CH₂SS(=O)H]* intermediate, which decomposes exothermically to lower energy CH₂ = S + HSO. The CH₃SS(=O)–H bond energy is quite weak at 54.8 kcal mol^?1 with the H–C bond estimated at between 91 and 98 kcal mol^?1. Disulfide bond energies for CH₃S–SOH and CH3S–S(=O)H are low: 67.1 and 39.2 kcal mol^?1. Copyright © 2011 John Wiley & Sons, Ltd.     

A novel block encryption scheme based on chaos and an S-box for wireless sensor networks

The wireless sensor network (WSN) has been widely used in various fields, but it still remains in the preliminary discovery and research phase with a lack of various related mature technologies. Traditional encryption schemes are not suitable for wireless sensor networks due to intrinsic features of the nodes such as low energy, limited computation capability, and lack of storage resources. In this paper, we present a novel block encryption scheme based on the integer discretization of a chaotic map, the Feistel network structure, and an S-box. The novel scheme is fast, secure, has low resource consumption and is suitable for wireless sensor network node encryption schemes. The experimental tests are carried out with detailed analysis, showing that the novel block algorithm has a large key space, very good diffusion and disruptive performances, a strict avalanche effect, excellent statistical balance, and fast encryption speed. These features enable the encryption scheme to pass the SP800-22 test. Meanwhile, the analysis and the testing of speed, time, and storage space on the simulator platform show that this new encryption scheme is well able to hide data information in wireless sensor networks.     

Validation of an extractive, airborne, compact TDL spectrometer for atmospheric humidity sensing by blind intercomparison

Accuracy, precision, repeatability and long-term stability, are the most important requirements to enable reliable airborne humidity measurements, which are needed for climate models or to validate e.g. remote sensing instrumentation like satellites. However, various hygrometer artifacts which depend on the individual sensor principle and the application profile frequently cause problems and significantly complicate the hygrometer choice. Sensor intercomparisons are one way of providing the information for an optimal choice. In this paper we present the first part of a blind, static, laboratory-based intercomparison of a new, calibration-free, 1.4 μm diode laser-based, optical hygrometer (SEALDH) with the two most important measurement principles for airborne hygrometry (frost-point hygrometers, FPH, and Lyman-alpha fluorescence hygrometers, LAFH). During three days of measurement, the TDL-hygrometer achieved a H₂O resolution of up to 0.5 ppmv (Δt=2 sec) at tropospheric pressure and H₂O concentration levels (100–800 hPa, 10 to 8000 ppmv H₂O). Its absolute accuracy was investigated via blind intercomparison with two reference FPHs and a LAFH. Without any calibration of SEALDH, i.e. without a comparison to a water vapor standard, we achieve an excellent agreement with the reference sensors, with an average systematic offset (over all three days) of ?3.9 %±1.5 %, which is fully consistent with the sensor’s uncertainty bounds. Further we also reevaluated the SEALDH data of day 2 and 3 in a calibrated mode using an independent set of FPH data from the first day and found an 8-fold accuracy improvement, yielding an excellent overall relative deviation of only 0.52 %±1.5 % with respect to a LAFH and a D/FH sensor.     

基于有机吡啶盐晶体的太赫兹频率上转换探测

利用激光泵浦国产有机吡啶盐4-(4-二甲基氨基苯乙烯基)甲基吡啶对甲基苯磺酸盐(4-N,N-dimethylamino-4′-N′-methyl-stilbazolium tosylate,DAST)晶体,通过非线性频率上转换方法实现了室温运转的高灵敏、快响应、宽频段太赫兹探测.高效生成了近红外上转换光,采集到其脉冲包...     

基于稀土掺杂光纤的强度调制型弯曲传感器

研究了一种基于稀土掺杂材料的新型周期性微拉锥玻璃光纤及其弯曲传感应用技术. 该光纤的纤芯和包层分别由两种硅酸铅玻璃材料组成,具有可塑性好和易于形成微拉锥的特点. 该传感器的核心敏感体由聚焦的CO₂激光束对稀土掺杂光纤进行周期性和等间距加热方式制备. 论文以该敏感体为核心,结合精密位置移动平台和光学测量平台,构建了基于强度调制的弯曲传感测量系统. 理论研究和实验结果表明,这种弯曲传感测量系统的传输光强灵敏度达到-28.2 μW/m,测量误差低于±1%,具备实际的工程应用价值. 关键词： 稀土掺杂光纤 微拉锥 弯曲传感 强度调制