This paper studies the issue of tax evasion in the context of the underground economy. A dynamic general equilibrium model is built where individual households and entrepreneurs decide rationally whether to go underground and under-report their earnings. These behaviors affect tax revenues, which are used to finance productive public services. This model is applied to the Czech Republic, becaus...

underground economy affects important indexes such as formal gdp, unemployment, consumption, production and etc. therefore it is necessary to identify elements and factors which affect underground economy to restrict it. surveys and studies indicate the size of iran’s underground economy is high and taxes, quantity and quality of regulations and performance of formal economy are the important f...

The foundation framework for underground spatial data aims to establish the platform for the underground spatial data sharing and integrating. The reasons lie in that: a) the long-term development of city construction has accumulated abundant underground spatial data and information; b) the development and utilization of city underground space demands for clear, detailed and visualized comprehe...

Hydrogen is becoming an increasingly important energy carrier in sector integration for fuel cell transportation, heat and electricity. Underground salt caverns are one of the most promising ways to store hydrogen obtained from water electrolysis using power generation renewable sources (RES). At same time, production can be used avoid curtailments during times low electricity demand or prices....

The paper approaches the necessity and implementation of a viable solution for constant saline water evacuation, its transportation to surface mine. A major problem in Slanic Prahova salt mine has been found be infiltration. Sump flooding is due high humidity condensation air circulating along Unirea sump, making exchange between underground surface, at temperature 12-15 degrees. Water infiltra...

Wireless Underground Sensor Networks (WUSN) constitute one of the promising application areas of the recently developed wireless sensor networking techniques. The main difference between WUSN and the terrestrial wireless sensor networks is the communication medium. The propagation characteristics of electromagnetic (EM) waves in soil and the significant differences between propagation in air pr...

Due to the high attenuation of radio frequency (RF) signals in underground mines and the statutory power restriction of communication gadgets especially for coal mines, the wireless communication systems have restricted applications in the underground mines. The paper discusses different radio frequency communication techniques being employed for Indian underground mines. Experiments were condu...

Due to its unique sensitivity to hydrogen protons, magnetic resonance sounding (MRS) is the only geophysical method that directly detects water and can provide nondestructive information on subsurface aquifer properties. The relationship between the surface MRS signal and the location and characteristics of aquifers using large-coil (typically 50-150 m) sensors has been discussed based on forwa...

Many coal mine companies have established underground safety monitor and control systems. However, the safety management information can only be displayed on the 2D maps or as reports. In this paper, a new method that combines the VR technologies with underground mine safety monitoring technologies was explored. A desktop virtual reality program for underground coal mine, called VRLane, was dev...

This study examined the effect of underground water on reproductionand growth-related hormones in blue gourami males under non-reproductive and reproductive conditions. An increase in the percentage of males building nests under the highest percentage of underground water were compared to fish that maintained a lower percentage of underground water in the first two days. The % Gonado-somatic in...