Air transparent soundproof window

A soundproof window or wall which is transparent to airflow is presented. The design is based on two wave theories of diffraction and acoustic metamaterials. It consists of a three-dimensional array of strong diffraction-type resonators with many holes centered at each individual resonator. The acoustic performance levels of two soundproof windows with air holes of $20mm$ and $50mm$ diameters were measured. Sound waves of 80dB in the frequency range of $400 - 5,000Hz$ were applied to the windows. It was observed that the sound level was reduced by about $30 - 35$dB in the above frequency range with the $20mm$ window and by about $20 - 35$dB in the frequency range of $700 - 2,200Hz$ with the $50mm$ window. It is an extraordinary acoustic anti-transmission. The geometric factors which produced the effective negative modulus were obtained.Comment: 4 pages, 6 figures, 1 tabl

Processes and Techniques for Rapid Bridge Replacement After Extreme Events

Yong Bai and Seong Hoon Kim, Processes and Techniques for Rapid Bridge Replacement After Extreme Events, Transportation Research Record: Journal of the Transportation Research Board (Volume: 1991 issue: 1) pp. 54-61. Copyright © 2007 SAGE Publications. DOI: 10.3141/1991-07.Highway bridges, as critical components of the nation's transportation network, have received increased attention after the terrorist attacks on September 11, 2001, and subsequent potential threats to U.S. transportation systems. To respond to the potential threats on highway bridges, a pooled-fund research project was conducted to identify rapid bridge replacement processes and techniques after extreme events. These events include manufactured and natural disasters such as earthquakes, explosions, fires, floods, and hurricanes. To achieve the research objectives, the research team studied three cases of previous bridge replacements following extreme events. These cases are the I-40 Webbers Falls Bridge in Oklahoma, the I-95 Chester Creek Bridge in Pennsylvania, and the I-87 New York State Thruway Bridge in Yonkers, New York. By studying these cases, the research team first sought to identify and expand on lessons learned. Lessons learned from these cases benefit government agencies such as state departments of transportation, which are responsible for development of the enhanced emergency response plans for highway bridges, and the engineering and construction communities, which are responsible for design and reconstruction of the damaged bridges. Next, the research team determined the processes and techniques that were used in the rapid bridge replacements and outlined needed improvements so that the research community could investigate new technologies to advance current practices

Measuring the Effects of a Land Value Tax on Land Development

The objective of this research is to evaluate a land value tax as a potential policy tool to moderate sprawling development in Nashville, TN, the nation’s most sprawling metropolitan community with a population of one million or more. To achieve this objective, the hypothesis is empirically tested that a land value tax encourages more development closer to preexisting development than farther from preexisting development. Specifically, the marginal effects of a land value tax on the probability of land development is hypothesized to be greater in areas around preexisting development than in areas more distant from preexisting development. The findings show that the marginal effects of a land value tax on the probability of developing parcels that neighbored previously developed parcels was greater than the probability of developing parcels that did not neighbor previously developed parcels. This finding suggests that land value taxation could be used to design compact development strategies that address sprawling development.Land value tax, Land development model, Urban sprawl, Land Economics/Use, Community/Rural/Urban Development,

Negative Externalities on Property Values Resulting from Water Impairment: The Case of the Pigeon River Watershed

The following hypothesis was tested: Willingness to bear a negative water impairment externality differs between those who do and those who do not receive economic benefit from the impairment source, e.g., a paper mill. The hypothesis was tested using a hedonic analysis of ambient water quality in two discrete housing markets in the Pigeon River Watershed, which have been polluted by the operation of a paper mill. The results suggest that North Carolina residents of the subwatersheds with impaired river, who experience economic benefits from the paper mill in addition to harmful effects, do perceive the pollution as a negative externality, whereas they may have a willingness to bear a similar type of negative externality associated with impaired streams. In contrast, the effects of both degraded river and streams on property values is perceived as a negative externality by residents in the Tennessee side, who experience only harmful effects from the pollution. North Carolina residents may hold greater willingness to bear the harmful effects of pollution as a given condition in their decision-making process because they receive economic benefits from the paper mill, while this internalization of the negative externality is weaker for residents in the Tennessee side.negative Externalities, water quality, spatial hedonic model, Environmental Economics and Policy,

Measuring Interactions among Agricultural Productivity, Trade Openness, Agricultural GDP, and Income in Korea (1972- 2007)

Agricultural and Food Policy,

Generalized gravity model for human migration

The gravity model (GM) analogous to Newton's law of universal gravitation has successfully described the flow between different spatial regions, such as human migration, traffic flows, international economic trades, etc. This simple but powerful approach relies only on the 'mass' factor represented by the scale of the regions and the 'geometrical' factor represented by the geographical distance. However, when the population has a subpopulation structure distinguished by different attributes, the estimation of the flow solely from the coarse-grained geographical factors in the GM causes the loss of differential geographical information for each attribute. To exploit the full information contained in the geographical information of subpopulation structure, we generalize the GM for population flow by explicitly harnessing the subpopulation properties characterized by both attributes and geography. As a concrete example, we examine the marriage patterns between the bride and the groom clans of Korea in the past. By exploiting more refined geographical and clan information, our generalized GM properly describes the real data, a part of which could not be explained by the conventional GM. Therefore, we would like to emphasize the necessity of using our generalized version of the GM, when the information on such nongeographical subpopulation structures is available.Comment: 14 pages, 6 figures, 2 table