The study area is located in the western extension of the Nile Valley near the boundary with the Western Desert, where the groundwater represents the potential water resource for future land development for both indus...The study area is located in the western extension of the Nile Valley near the boundary with the Western Desert, where the groundwater represents the potential water resource for future land development for both industrial purposes and agricultural reclamation. Historically, geoelectric methods proved prospective and practical in exploring for groundwater resources. In this study, 17 Vertical Electric Sounding (VES) were acquired and processed to reveal the subsurface distribution of the water bearing layers and identify the groundwater potential in West Maghagha area. After routine data analysis and calibration, the preliminary results are interpreted in light of the available geological data and indicated the presence of at least four geoelectric layers with model resistivity values up to 2000 Ω•m. The potential aquifer was encountered down to ~120 m depth with average thickness of 100 m and is made of argillaceous fractured carbonates. Despite the overall poor quality of this aquifer, the integrated geoelectric and hydrogeologic information indicated a possible potential occurrence of potable groundwater at the southern and northeastern parts of the study area. To improve understanding of the groundwater systems in the study area, detailed aquifer characterization is discussed through integration of the available geologic data, maps, and the geoelectric sections constructed from the VES.展开更多
By using the concept of complex sound intensity, the rotational character of the active sound intensity which is the real component of the complex sound intensity is descussed in this paper. It is shown that it is the...By using the concept of complex sound intensity, the rotational character of the active sound intensity which is the real component of the complex sound intensity is descussed in this paper. It is shown that it is the irrotational component of the active sound intensity that transfers sound energy in sound field. When sound power is measured with the two- microphone technique, the rotation of the active sound intensity has an effect on it. Because the irrotational component of the active sound intensity depends only on the surface sound intensity, measuring the surface sound intensity can avoid the effect of the rotation. Based on atuo- power spectra, formulas about the surface sound intensity are given in this paper, providing a theoretical basis for measuring the surface sound intensity.展开更多
An experimental study for the characterization of ventilation fans as sources of structure-borne sound has been carried out. A source descriptor is proposed which is proportional to power and involves both the free ve...An experimental study for the characterization of ventilation fans as sources of structure-borne sound has been carried out. A source descriptor is proposed which is proportional to power and involves both the free velocity and the source mobility at the contact point. The measurement methods for the free velocity and the source mobility for three degrees of freedom are presented and the estimation of the source descriptor is demonstrated. A comparison of force excitation source descriptors and moment excitation source descriptors has been made and the results indicate that both force descriptor and moment descriptor decrease with increased frequency but the moment descriptor decreases more slowly. Moment induced emission may predominate at high frequencies.展开更多
文摘The study area is located in the western extension of the Nile Valley near the boundary with the Western Desert, where the groundwater represents the potential water resource for future land development for both industrial purposes and agricultural reclamation. Historically, geoelectric methods proved prospective and practical in exploring for groundwater resources. In this study, 17 Vertical Electric Sounding (VES) were acquired and processed to reveal the subsurface distribution of the water bearing layers and identify the groundwater potential in West Maghagha area. After routine data analysis and calibration, the preliminary results are interpreted in light of the available geological data and indicated the presence of at least four geoelectric layers with model resistivity values up to 2000 Ω•m. The potential aquifer was encountered down to ~120 m depth with average thickness of 100 m and is made of argillaceous fractured carbonates. Despite the overall poor quality of this aquifer, the integrated geoelectric and hydrogeologic information indicated a possible potential occurrence of potable groundwater at the southern and northeastern parts of the study area. To improve understanding of the groundwater systems in the study area, detailed aquifer characterization is discussed through integration of the available geologic data, maps, and the geoelectric sections constructed from the VES.
基金supported by the Anhui Provincial Department of Science and Technology(18030801138)the National Natural Science Foundation of China(61705216,12174368,62122072)the Zhejiang Lab(2019MC0AB01)。
文摘By using the concept of complex sound intensity, the rotational character of the active sound intensity which is the real component of the complex sound intensity is descussed in this paper. It is shown that it is the irrotational component of the active sound intensity that transfers sound energy in sound field. When sound power is measured with the two- microphone technique, the rotation of the active sound intensity has an effect on it. Because the irrotational component of the active sound intensity depends only on the surface sound intensity, measuring the surface sound intensity can avoid the effect of the rotation. Based on atuo- power spectra, formulas about the surface sound intensity are given in this paper, providing a theoretical basis for measuring the surface sound intensity.
文摘An experimental study for the characterization of ventilation fans as sources of structure-borne sound has been carried out. A source descriptor is proposed which is proportional to power and involves both the free velocity and the source mobility at the contact point. The measurement methods for the free velocity and the source mobility for three degrees of freedom are presented and the estimation of the source descriptor is demonstrated. A comparison of force excitation source descriptors and moment excitation source descriptors has been made and the results indicate that both force descriptor and moment descriptor decrease with increased frequency but the moment descriptor decreases more slowly. Moment induced emission may predominate at high frequencies.
