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91.
Tse MS Chau CK Choy YS Tsui WK Chan CN Tang SK 《The Journal of the Acoustical Society of America》2012,131(4):2762-2771
A number of studies have been initiated to explore how to improve the soundscape quality in urban parks. However, good soundscape quality in parks cannot be provided without a thorough understanding of the complex relationships among sound, environment, and individuals. As acoustic comfort is considered to be an important outcome of soundscape quality, this study investigates the relative impacts of the factors influencing acoustic comfort evaluation by formulating a multivariate ordered logit model. This study also explores the inter-relationships among acoustic comfort evaluation, acceptability of the environment, and preference to stay in a park using a path model. A total of 595 valid responses were obtained from interview surveys administered in four parks in Hong Kong while objective sound measurements were carried out at the survey spots concurrently. The findings unveil that acoustic comfort evaluation, besides visual comfort evaluation of landscape, also plays an important role on users' acceptability of the urban park environment. Compared with all the studied acoustic related factors, acoustic comfort evaluation serves as a better proxy for park users' preference to stay in urban parks. Hearing the breeze will significantly increase the likelihood of individuals in giving high acoustic comfort evaluation. Conversely, hearing the sounds from heavy vehicles or sounds from bikes will significantly reduce the likelihood in giving a high acoustic evaluation. 相似文献
92.
This study investigates plasmonic Bloch oscillations (PBOs) in cylindrical metal-dielectric waveguide arrays (MDWAs) by performing numerical simulations and theoretical analyses. Optical conformal mapping is used to transform cylindrical MDWAs into equivalent chirped structures with permittivity and permeability gradients across the waveguide arrays, which is caused by the curvature of the cylindrical waveguide. The PBOs are attributed to the transformed structure. The period of oscillation increases with the wavelength of the incident Gaussian beam. However, the amplitude of oscillation is almost independent of wavelength. 相似文献
93.
Li HN Chau CK Tse MS Tang SK 《The Journal of the Acoustical Society of America》2012,131(3):2131-2140
Noise annoyance has caused significant adverse impacts on human beings and numerous efforts have been spent on mitigating annoyance problems. Natural greenery has been shown to be able to moderate annoyance problems at home but this conclusion was drawn without properly controlling the potential confounding factors. Furthermore, few have explored the moderation effect of a sea view. Accordingly, this study formulated a multivariate model to examine the impacts of natural views as well as personal characteristics on annoyance perception. A housing estate was selected in Hong Kong as the survey site for which some of the residents were exposed to greenery views, sea views, or both from their homes. Eight hundred and sixty-one responses were collected via questionnaire surveys and analyzed using an ordered logit model. The results suggest that both a greenery view and a sea view can moderate annoyance responses. Several individual's personal characteristics are found to affect individuals' annoyance perception. The duration of time spent daily at home is shown to have an influence on the moderation impact exerted by a greenery view, while the age of an individual is shown to have an influence on noise moderation effect exerted by a sea view. 相似文献
94.
Motivated by the desire to improve our understanding of the Weak Gravity Conjecture, we compute the one-loop correction of charged particles to the geometry and entropy of extremal black holes in 4D. We use the entropy function formalism to extend previous analysis that dealt with neutral particles, and obtain the corrections to the horizon entropy for different regimes of black hole masses. These corrections are small in general. They are furthermore reduced when supersymmetry is present, and disappear in N = 4 supergravity. We provide some speculative arguments that in a theory with only sub-extremal particles, classical Reissner-Nordstrom black holes actually possess an infinite microcanonical entropy, though only a finite amount is visible to an external observer, as shown by the horizon entropy computation. 相似文献
95.
96.
Kom-Bei Shiu Shin-Jay Yu Yu Wang Gene-Hsiang Lee 《Journal of organometallic chemistry》2002,650(1-2):37-42
Treatment of [Ru2(CO)4(MeCN)6][BF4]2 or [Ru2(CO)4(μ-O2CMe)2(MeCN)2] with uni-negative 1,1-dithiolate anions via potassium dimethyldithiocarbamate, sodium diethyldithiocarbamate, potassium tert-butylthioxanthate, and ammonium O,O′-diethylthiophosphate gives both monomeric and dimeric products of cis-[Ru(CO)2(η2-(SS))2] ((SS)−=Me2NCS2− (1), Et2NCS2− (2), tBuSCS2− (3), (EtO)2PS2− (4)) and [Ru(CO)(η2-(Me2NCS2))(μ,η2-Me2NCS2)]2 (5). The lightly stabilized MeCN ligands of [Ru2(CO)4(MeCN)6][BF4]2 are replaced more readily than the bound acetate ligands of [Ru2(CO)4(μ-O2CMe)2(MeCN)2] by thiolates to produce cis-[Ru(CO)2(η2-(SS))2] with less selectivity. Structures 1 and 5 were determined by X-ray crystallography. Although the two chelating dithiolates are cis to each other in 1, the dithiolates are trans to each other in each of the {Ru(CO)(η2-Me2NCS2)2} fragment of 5. The dimeric product 5 can be prepared alternatively from the decarbonylation reaction of 1 with a suitable amount of Me3NO in MeCN. However, the dimer [Ru(CO)(η2-Et2NCS2)(μ,η2-Et2NCS2)]2 (6), prepared from the reaction of 2 with Me3NO, has a structure different from 5. The spectral data of 6 probably indicate that the two chelating dithiolates are cis to each other in one {Ru(CO)(η2-Et2NCS2)2}fragment but trans in the other. Both 5 and 6 react readily at ambient temperature with benzyl isocyanide to yield cis-[Ru(CO)(CNCH2Ph)(η2-(SS))2] ((SS)=Me2NCS2− (7) and Et2NCS2− (8)). A dimerization pathway for cis-[Ru(CO)2(η2-(SS))2] via decabonylation and isomerization is proposed. 相似文献
97.
Synthesis and Characterization of Poly(ethylene terephthalate)/Modified Lithium‐Aluminum‐Layered Double Hydroxide Nanocomposites Prepared Using In‐situ Polymerization 下载免费PDF全文
Layered double hydroxides are a type of layered stacked compound, which can be intercalated with organic‐molecule modifiers. An ion‐exchange process for layered double hydroxide (LDH) was used to intercalate water‐soluble sulfanilic acid salt (SAS) and dimethyl 5‐sulfoisopthalate (DMSI) into lithium aluminum layered double hydroxides (LiAl LDHs). In this work, a hydrothermal process was used to modify LiAl LDHs, and the modified LiAl LDHs were treated with either SAS or DMSI through an ion‐exchange process and were then intercalated using bis‐hydroxyethylene terephthalate (BHET). The results indicate that the modified LiAl LDHs improved the interlayer compatibility between the PET and LiAl LDH layers; thus, enabling the oligomer molecules to more easily enter the gallery of the LiAl LDH layers so that polymer chains could be included between the LDH layers during polymerization of the matrix. The better barrier, mechanical properties, and thermal stability of these new types of PET nanocomposites are discussed. 相似文献
98.
A novel chemically modified electrode based on an osmium complex-containing redox polymer film coated on single-walled carbon nanotube (SWNT) modified glassy carbon electrode (GCE) has been described for the determination of nitric oxide. The results showed that the oxidation current increased significantly at the SWNT/redox polymer coated GCE, as compared to that observed on a bare GCE- and SWNT-modified GCE. Amperometric measurement was carried out at the potential of +0.80?V (vs. Ag|AgCl) and the current response to NO was found to be directly proportional to its concentration in the range from 2.0?×??0?? to 4.0?×??0?? M, and the detection limit was estimated to be 5.0?×??0?? M. 相似文献
99.
Lin JL Lin YS Shih JJ Kuo KH Lin SK Wu TS Shiu MY 《The Journal of chemical physics》2011,135(6):064706
Temperature-programmed reaction/desorption, mass spectrometry, reflection-absorption infrared spectroscopy, x-ray photoelectron spectroscopy, and density functional theory calculations have been employed to explore the reaction and bonding structure of 1,2-C(2)H(4)Br(2) on Cu(100). Both the trans and gauche conformers are found to dissociate by breaking the C-Br bonds on clean Cu(100) at 115 K, forming C(2)H(4) and Br atoms. Theoretical investigations for the possible paths of 1,2-C(2)H(4)Br(2) → C(2)H(4) + 2Br on Cu(100) suggest that the barriers of the trans and gauche molecules are in the ranges of 0-4.2 and 0-6.5 kcal/mol, respectively. The C-Br scission temperature of C(2)H(4)Br(2) is much lower than that (~170 K) of C(2)H(5)Br on Cu(100). Adsorbed Br atoms can decrease the dissociation rate of the 1,2-C(2)H(4)Br(2) molecules impinging the surface. The 1,2-C(2)H(4)Br(2) molecules adsorbed in the first monolayer are structurally distorted. Both the trans and gauche molecules exist in the second monolayer, but with no preferential adsorption orientation. However, the trans molecule is the predominant species in the third or higher layer formed at 115 K. The layer structure is not thermally stable. Upon heating the surface to 150 K, the orientation of the trans 1,2-C(2)H(4)Br(2) molecules in the layer changes, leading to the rotation of the BrCCBr skeletal plane toward the surface normal on average and the considerable growth of the CH(2) scissoring peak. On oxygen-precovered Cu(100), decomposition of 1,2-C(2)H(4)Br(2) to form C(2)H(4) is hampered and no oxygenated hydrocarbons are formed. The presence of the oxygen atoms also increases the adsorption energy of the second-layer molecules. 相似文献
100.