In arbitrary Riemannian 4-spaces, continuity equations are constructed which could be interpreted as conservation laws for the energy and momentum of the gravitational field. Special attention is given to general rela...In arbitrary Riemannian 4-spaces, continuity equations are constructed which could be interpreted as conservation laws for the energy and momentum of the gravitational field. Special attention is given to general relativity to obtain, of natural manner, the pseudotensors of Einstein, Landau-Lifshitz, Moeller, Goldberg and Stachel, and also the conservation equations of Komar, Trautman, DuPlessis and Moss.展开更多
The problem of contamination of Lerma River in the State of Mexico, México, has been studied in an integral way, since it is one of the rivers of importance due to its geographical situation in the country. Jos&#...The problem of contamination of Lerma River in the State of Mexico, México, has been studied in an integral way, since it is one of the rivers of importance due to its geographical situation in the country. José Antonio Dam is the main receiving body of this river that is being contaminated by, industrial wastewater, of which about 70% is inorganic, as well as discharges municipal and agricultural, driving a lot of material in suspension. This dam acts as a regulator of avenues and its water is used for agricultural irrigation and its sediments are used as sludge to improve agricultural soil in the surroundings. One of the studies that have been carried out is to determine the geochemical distribution of heavy metals in the sediments of this dam, as well as its adsorptive capacity towards different metals. It has been observed that these sediments acts as metal contaminants sequester. Knowing the composition and morphology of these sediments can provide information to understand the mobility of different heavy metals it contains, and potential health risk, which can finally lead to the establishment of purification capacity of this sludge.展开更多
There is a constant growth in the demand of data information transmission capacity, that is, more and more people send data, voice, video signals, among others, through communications networks. Due to the above there ...There is a constant growth in the demand of data information transmission capacity, that is, more and more people send data, voice, video signals, among others, through communications networks. Due to the above there is great interest in improving network devices, such as optical amplifiers, which must cover a large bandwidth and generate greater gain than those currently available. For this reason in this work a computational simulation for a Quasi-system was carried out</span></span><span><span><span style="font-family:""> </span></span></span><span><span><span style="font-family:"">three energy levels of Erbium and Ytterbium varying their concentrations and proving that they are optimal candidates in a zinc phosphate matrix as this type of glass contains properties such as, high transparency, low melting point, high thermal stability, high gain density due to high solubility, low refractive index and low dispersion, which makes them optimal as signal amplifiers. The results confirm that by increasing the doping of the Erbium ion the gain of the amplifier decreases, contrary to the Ytterbium ion that by increasing the doping the gain of the amplifier increases.展开更多
文摘In arbitrary Riemannian 4-spaces, continuity equations are constructed which could be interpreted as conservation laws for the energy and momentum of the gravitational field. Special attention is given to general relativity to obtain, of natural manner, the pseudotensors of Einstein, Landau-Lifshitz, Moeller, Goldberg and Stachel, and also the conservation equations of Komar, Trautman, DuPlessis and Moss.
文摘The problem of contamination of Lerma River in the State of Mexico, México, has been studied in an integral way, since it is one of the rivers of importance due to its geographical situation in the country. José Antonio Dam is the main receiving body of this river that is being contaminated by, industrial wastewater, of which about 70% is inorganic, as well as discharges municipal and agricultural, driving a lot of material in suspension. This dam acts as a regulator of avenues and its water is used for agricultural irrigation and its sediments are used as sludge to improve agricultural soil in the surroundings. One of the studies that have been carried out is to determine the geochemical distribution of heavy metals in the sediments of this dam, as well as its adsorptive capacity towards different metals. It has been observed that these sediments acts as metal contaminants sequester. Knowing the composition and morphology of these sediments can provide information to understand the mobility of different heavy metals it contains, and potential health risk, which can finally lead to the establishment of purification capacity of this sludge.
文摘There is a constant growth in the demand of data information transmission capacity, that is, more and more people send data, voice, video signals, among others, through communications networks. Due to the above there is great interest in improving network devices, such as optical amplifiers, which must cover a large bandwidth and generate greater gain than those currently available. For this reason in this work a computational simulation for a Quasi-system was carried out</span></span><span><span><span style="font-family:""> </span></span></span><span><span><span style="font-family:"">three energy levels of Erbium and Ytterbium varying their concentrations and proving that they are optimal candidates in a zinc phosphate matrix as this type of glass contains properties such as, high transparency, low melting point, high thermal stability, high gain density due to high solubility, low refractive index and low dispersion, which makes them optimal as signal amplifiers. The results confirm that by increasing the doping of the Erbium ion the gain of the amplifier decreases, contrary to the Ytterbium ion that by increasing the doping the gain of the amplifier increases.
