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101.
Discriminant Analysis is used as a part of a research, which aims at using expired air analysis for the early location of entrapped people under the ruins of collapsed buildings in an earthquake. This work focuses on the possibility of distinguishing Volatile Organic Compounds (VOCs) in the entrapment area which originate from different sources. Five categories of samples were analyzed by Thermal Desorption-Gas Chromatography-Mass Spectrometry (TD-GC-MS). Expired air samples from healthy humans (Category 1) and fasting people (Category 2) were analyzed for studying the VOCs attributed to entrapped people. Headspace air of urban waste disposal bins (Category 3), headspace air of bags with decaying human bodies (Category 4) and urban air samples (Category 5) were analyzed for studying the VOCs attributed to background sources. Discriminant Rotation, a specific type of Discriminant Analysis was applied on the VOCs concentration matrix of the five categories. Combinations of VOCs that best discriminated each category were determined. Cluster Analysis was used to validate the results of Discriminant Analysis. The advantages and limitations of the method are presented and discussed. 相似文献
102.
《Arabian Journal of Chemistry》2020,13(9):7115-7131
The impregnation of magnetite (Mt) nanoparticle (NPs) onto Musa acuminata peel (MApe), to form a novel magnetic combo (MApe-Mt) for the adsorption of anionic bromophenol blue (BPB) was studied. The SEM, EDX, BET, XRD, FTIR and TGA were used to characterize the adsorbents. The FTIR showed that the OH and CO groups were the major sites for BPB uptake onto the adsorbent materials. The average Mt crystalline size on MApe-Mt was 21.13 nm. SEM analysis revealed that Mt NPs were agglomerated on the surface of the MApe biosorbent, with an average Mt diameter of 25.97 nm. After Mt impregnation, a decrease in BET surface area (14.89 to 3.80 m2/g) and an increase in pore diameter (2.25–3.11 nm), pore volume (0.0052–0.01418 cm3/g) and pH point of zero charge (6.4–7.2) was obtained. The presence of Pb(II) ions in solution significantly decreased the uptake of BPB onto both MApe (66.1–43.8%) and MApe-Mt (80.3–59.1%), compared to other competing ions (Zn(II), Cd(II), Ni(II)) in the solution. Isotherm modeling showed that the Freundlich model best fitted the adsorption data (R2 > 0.994 and SSE < 0.0013). In addition, maximum monolayer uptake was enhanced from 6.04 to 8.12 mg/g after Mt impregnation. Kinetics were well described by the pseudo-first order and liquid film diffusion models. Thermodynamics revealed a physical, endothermic adsorption of BPB onto the adsorbents, with ΔHo values of 15.87–16.49 kJ/mol, corroborated by high desorption (over 90%) of BPB from the loaded materials. The viability of the prepared adsorbents was also revealed in its reusability for BPB uptake. 相似文献
103.
Gerhard Schomburg Alfred Deege Heike Hinrichs Eduard Hübinger Heribert Husmann 《Journal of separation science》1992,15(9):579-584
Methods of alkylation of α-, β- and γ-cyclodextrins have been optimized with regard to the parameters of reaction, degree of alkylation and yields. The analysis of the reaction mixtures and of the isolated single species has been performed by high temperature GC and HPLC. The phase systems of the preferably applied HPLC have been carefully adjusted by variation of both the stationary and mobile phases to the very different hydrophobicities of the various alkylated CD species which have been synthesized. Several partially or fully alkylated CD species were isolated from preparative scale HPLC separations in high purity. 相似文献
104.
105.
《Journal of Coordination Chemistry》2012,65(9):985-990
The crystal of pentaqua (catena-pyridine-3,5-dicarboxylato-O,O) calcium(II) contain zigzag molecular chains composed of Ca ions linked by two bridging oxygen atoms, each donated by one carboxylate group [Ca-O1 2.353(2) Å, Ca-O3III 2.334(1) Å]. The Ca ions, the ligand molecules and one water oxygen atom coordinated by each metal ion [Ca-O5 2.410(2) Å] are coplanar. The coordination of the Ca ion is completed by four other water oxygen atoms situated above and below the plane of the chain [Ca-O6 2.475(1) Å, Ca-O7 2.371(2) Å]. The coordination number of the calcium(II) ion is seven. The water molecules act as donors in a system of hydrogen bonds. 相似文献
106.
A fast procedure has been developed for the direct determination of paint solvents. The method is based on the injection of small volumes of untreated solvent mixtures into a heated Pyrex glass reactor in which the sample is volatilized and introduced by means of a flow of nitrogen into an IR multiple pass gas cell and the spectrum in the mid-IR region is registered as a function of time. Data found for samples are interpolated in calibration graphs obtained by injecting different volumes of pure compounds which constitute the solvent mixture. A methylisobutylketone (MIBK) toluene mixture was used as test system to develop the proposed procedure. The method provides a limit of detection of the order of 1–4 μg, a relative standard deviation of the order of 0.4 to 2% for five independent measurements, and recovery percentage values from 99.8 till 103.6 %. A commercial sample of polyurethane paint solvent has been analysed by the developed procedure. 相似文献
107.
Importance of verifying queue model assumptions before planning with simulation software 总被引:1,自引:0,他引:1
Kenneth David Strang 《European Journal of Operational Research》2012,218(2):493-504
This case study uses empirical data gathered at an Australian refinery to verify the assumptions for queue distributions before using special-purpose software to plan the off-road-truck hauling of titanium dioxide to a refinery (n = 773). Easy-to-use spreadsheet software is utilized to verify assumptions for queue models. Managers are able to make decisions based on economic implications of queue models to avoid making costly planning mistakes. Analysts can use nonparametric hypothesis-testing techniques to verify distribution assumptions for optimization without having to write hard-to-maintain and complex algebraic linear equations or nonlinear search routines. 相似文献
108.
Multi-watermarking is the technique to embed multiple messages into the same media content repeatedly. It can be used to identify media content's ownership or trace the illegal redistributors in media distribution. However, some performances of multiple watermark embedding, e.g., the distortion and security, are not considered carefully in the previous work. In this paper, the application scenario and framework of hybrid multi-watermarking are figured out, which show the secure media distribution model suitable for hierarchical media distribution. Additionally, the multi-watermarking based on hybrid multiplicative rule is firstly proposed and then analyzed theoretically with respect to two cases, i.e., the multi-embedding of same watermark sequence and the multi-embedding of different watermark sequences. The analysis emphasizes on four aspects, i.e., robustness, capacity, distortion and security, each of which considers two cases, i.e., the authorized embedding and unauthorized embedding. What is more, the locally optimum detector for multi-watermarking of hybrid multiplicative rule is reduced, and some potential attacks are investigated. Additionally, for each case, some suggestions are proposed to improve the system's performance. Finally, some comparative experiments are done, and results are given to show the validity of the theoretical analysis. 相似文献
109.
Mohammed Nabil El Korso Rémy Boyer Alexandre Renaux Sylvie Marcos 《Signal processing》2012,92(2):547-552
In this fast communication, we derive the statistical resolution limit (SRL), characterizing the minimal parameter separation, to resolve two closely spaced known near-field sources impinging on a linear array. Toward this goal, we conduct on the first-order Taylor expansion of the observation model a Generalized Likelihood Ratio Test (GLRT) based on a Constrained Maximum Likelihood Estimator (CMLE) of the SRL. More precisely, the minimum separation between two near-field sources, that is detectable for a given probability of false alarm and a given probability of detection, is derived herein. Finally, numerical simulations are done to quantify the impact of the array geometry of the signal sources power distribution and of the array aperture on the statistical resolution limit. 相似文献
110.
We consider the problem of recovering a two-dimensional periodic structure from scattered waves measured above the structure. Following an approach by Kirsch and Kress, this inverse problem is reformulated as a nonlinear optimization problem. We develop a theoretical basis for the reconstruction method in the case of an arbitrary Lipschitz grating profile. The convergence analysis is based on new perturbation and stability results for the forward problem. 相似文献