Noise immunity estimation of diffraction stacking method on the example of a homogeneous model

© SGEM2018. Seismic sources location is one of the main tasks of seismology (determination of earthquake hypocenters) and this is the main task in microseismic monitoring of hydraulic fracturing. When choosing a method for microseismic monitoring, noise immunity is one of the main parameters, which should be considered in order to obtain reliable results. The article is referred to the location of a point seismic source by the Diffraction Stacking method applied to synthetic signals obtained using 2D numerical simulation of seismic waves propagation in an elastic medium. Simulation of seismic wave propagation was carried out using the finite difference scheme, which allows simulating the propagation of longitudinal and vertically polarized transverse waves. Noise immunity estimation was carried out by adding random noise to the synthetically simulated signals and then finding the maximum of the image function throughout the modelled area. The results obtained make it possible to characterize the Diffraction Stacking method as weakly stable to random noise, the amplitude of which is comparable with the amplitude of the useful signal. Nevertheless, in general this method of seismic sources location can be applied to process the data with relatively high signal-to-noise ratios

Noise immunity estimation of diffraction stacking method on the example of a homogeneous model

© SGEM2018. Seismic sources location is one of the main tasks of seismology (determination of earthquake hypocenters) and this is the main task in microseismic monitoring of hydraulic fracturing. When choosing a method for microseismic monitoring, noise immunity is one of the main parameters, which should be considered in order to obtain reliable results. The article is referred to the location of a point seismic source by the Diffraction Stacking method applied to synthetic signals obtained using 2D numerical simulation of seismic waves propagation in an elastic medium. Simulation of seismic wave propagation was carried out using the finite difference scheme, which allows simulating the propagation of longitudinal and vertically polarized transverse waves. Noise immunity estimation was carried out by adding random noise to the synthetically simulated signals and then finding the maximum of the image function throughout the modelled area. The results obtained make it possible to characterize the Diffraction Stacking method as weakly stable to random noise, the amplitude of which is comparable with the amplitude of the useful signal. Nevertheless, in general this method of seismic sources location can be applied to process the data with relatively high signal-to-noise ratios

Integration of the seismic and geochemistry data to evaluate hydrocarbon potential of the carbonate reservoirs in Tatarstan, Russia

© SGEM2018. The article describes the results of the integration of the geochemical and seismic data on one of the oilfields of Tatarstan Republic in Russian Federation. The complex geological structure of the oil bearing formations of Carboniferous age results in misinterpretation of the geophysical data and drilling of the dry wells. Some potential structural oil traps find from the seismic data interpretation are water bearing. To avoid nonproductive drilling authors studied seismic faults and their connection with the geochemical anomalies. On the first step the faults in the potential oil-bearing formation of the Tournaisian age were traced in the 2D seismic lines. Then the geochemical parameter (propane concentration in the soils) was studied in 90 observation points. The gas anomaly represented by propane is indicative, because the biochemical genesis of methane homologues is practically excluded, and their content in coal is insignificant. That means that the increased content of propane is connected with the presence of hydrocarbons. It appears that in the presents of oil in the formation geochemical anomaly and the fault in the Tournaisian formation are coincide. That can be used as additional source of information to avoid nonproductive drilling

Influence of tungsten nanoparticles on microstructure and mechanical properties of an Al-5%Mg alloy produced by casting

This paper investigates the impact of tungsten nanoparticles on the microstructure and mechanical properties of the Al-5Mg alloy. Tungsten concentrations of up to 0.5 wt.% led to a slight modification of the Al-5Mg alloy microstructure, and grain refinement occurred due to the inhibition of crystal growth along the boundaries. Dispersion hardening with tungsten nanoparticles made it possible to increase the ultimate strength by the Orowan mechanism with a simultaneous increase in the plasticity of the Al-5Mg alloy. An increase in the tungsten content to 0.8 wt.% made it possible to modify the microstructure of the Al-5Mg alloy, due to the formation of the Al12W phase and an increase in crystallisation centres. The modification of the microstructure, as well as dispersion strengthening by nanoparticles, led to a simultaneous increase in the yield strength, ultimate tensile strength, and ductility of the Al-5Mg alloy

Simulation of neutron transport for the purpose of neutron filters optimization in the pulsed neutron logging apparatus

© 2006-2015 Asian Research Publishing Network (ARPN). Numerical modeling of thermal neutron filters, which are an integral part of the apparatus of pulsed neutron logging (PNL), has been carried out. Many models of filters were created. The neutrons slowing down and absorption processes in filters was analyzed. Optimum structure and dimensions of neutron filters was offered

Evaluation of the possibility of obtaining welded joints of plates from Al-Mg-Mn aluminum alloys, strengthened by the introduction of TiB2 particles

In the work, the possibility of obtaining strong welded joints of aluminum alloys modified with particles is demonstrated. For research, strengthened aluminum alloys of the Al-Mg-Mn system with the introduction of TiB2 particles were obtained. TiB2 particles in specially prepared Al-TiB master alloys obtained by self-propagating high-temperature synthesis were introduced ex situ into the melt according to an original technique using ultrasonic treatment. Plates from the studied cast alloys were butt-welded by one-sided welded joints of various depths. To obtain welded joints, the method of electron beam welding was used. Mechanical properties of the studied alloys and their welded joints under tension were studied. It was shown that the introduction of particles resulted in a change in the internal structure of the alloys, characterized by the formation of compact dendritic structures and a decrease in the average grain size from 155 to 95 µm. The change in the internal structure due to the introduction of particles led to an increase in the tensile strength of the obtained alloys from 163 to 204 MPa. It was found that the obtained joints have sufficient relative strength values. Relative strength values reach 0.9 of the nominal strength of materials already at the ratio of the welded joint depth to the thickness of the welded plates, equal to 0.6 for the initial alloy and in the range of 0.67–0.8 for strengthened alloys

Forest Protection and Permanence of Reduced Emissions

Tropical forests are essential for climate change mitigation. As awareness grows over the use of credits from reduced emissions from deforestation and forest degradation (REDD+) and other nature-based climate solutions within both voluntary and compliance carbon markets, key concerns about the long-term durability of the reductions, or their permanence, arise for countries, corporations, regulators and policy makers. The paper seeks to analyze an efficient means of distribution and application of different policy pathways to slow down and stop deforestation and explore the longevity of reductions via modeling. The impact of policies like REDD+ most likely will have a time limitation. At some point tropical nations will take more responsibility to protect forests. REDD+ should constitute an initial intervention that will help tropical nations shock to a zero-deforestation trajectory. To establish conditions of permanence, we conduct numerical analyses using a model based on a cellular automata algorithm that learns from historical deforestation patterns and other spatial features in the Brazilian state of Mato Grosso. The model simulates future deforestation, first applying policy to reduce deforestation and then relaxing the policy intervention. Our simulations show that policies that are successful in reducing deforestation and related emissions from business as usual may have long-term positive consequences on an avoided deforestation trajectory even after potential policy reversals. Some accumulated gains could be lost but sizable benefits will remain, assuring permanence of emissions reduction during the policy implementation and potentially even after policies are relaxed. Hence, permanence depends both on the probability of policy reversals and the risk of emissions rebounding. Our results are important for advancing the understanding around the unsettled debate on the permanence of avoided emissions. Further, this paper argues that as policies to prevent deforestation or reduce emissions otherwise are reversible, permanence should be understood and discussed in a probabilistic and time-dependent framework

Moose or spruce: A systems analysis model for managing conflicts between moose and forestry in Sweden

Sweden has the world’s highest density of moose (Alces alces). Moose is not only a valuable game species; it also causes forest damages and traffic accidents. To avoid moose browsing, foresters respond by planting spruce (Picea abies) to an extent that reshapes the forest landscape with impacts on both production and biodiversity. To address this problem and maintain a healthy moose population in balance with the other interests, an adaptive management based on the knowledge and experiences of local hunters and landowners is advocated. However, the different stakeholders do not agree on what is an appropriate moose population, which leads to conflicts that are hard to resolve. A key problem is that it is very difficult to encompass and foresee long-term consequences of different options for moose hunting and forest management. This makes it challenging to form coherent strategies that integrate different sectorial interests at a national level. To address this issue, we have developed a systems analysis framework for integrated modeling of the moose population, forestry, and their interactions and consequences for biodiversity. We analyze the short and long-term consequences for multiple scenarios of moose hunting and forest management. Based on the results we elucidate and quantify the trade-offs and possible synergies between moose hunting and forest production. This analysis can be used to support better informed and more constructive discussions among the stakeholders in the Swedish forest sectors, and to support policies for long term sustainable forest and moose management

Forest protection and permanence of reduced emissions

Tropical forests are essential for climate change mitigation. With growing interest over the use of credits from reducing emissions from deforestation and forest degradation (REDD+) and other natural climate solutions within both voluntary and compliance carbon markets, key concerns about the long-term durability of the reductions, or their permanence, arise for countries, corporations, regulators, and policy makers. This paper seeks to analyze the longevity of emissions reductions from different policies to slow down and stop deforestation. To establish conditions of permanence, we conduct numerical analyses using a model based on a cellular automata algorithm that learns from historical deforestation patterns and other spatial features in the Brazilian state of Mato Grosso. First, we simulate increased law enforcement to curb deforestation at a jurisdictional scale from 2025 to 2034, followed by potential policy rollbacks from 2035 to 2050. Second, we consider alternative scenarios to avoid potentially legal deforestation coupled with reforestation. We find spatial and path dependence – a successful policy intervention may permanently change the deforestation trajectory even after potential policy reversals. Hence, permanence depends both on the probability of policy reversals and the risk of emissions overshooting. Our results are important for advancing the understanding around the unsettled debate on the permanence of avoided emissions. Further, this paper argues that as policies to prevent deforestation or reduce emissions otherwise are reversible, permanence should be understood and discussed in a probabilistic and time-dependent framework

THEORY OF PHASE-LOCKING IN SMALL JOSEPHSON JUNCTION CELLS

Within the RSJ model, we performed a theoretical analysis of phase-locking in elementary strongly coupled Josephson junction cells. For this purpose, we developed a systematic method allowing the investigation of phase-locking in cells with small but non-vanishing loop inductance.The voltages across the junctions are found to be locked with very small phase difference for almost all values of external flux. However, the general behavior of phase-locking is found to be just contrary to that according to weak coupling. In case of strong coupling there is nearly no influence of external magnetic flux on the phases, but the locking-frequency becomes flux-dependent. The influence of parameter splitting is considered as well as the effect of small capacitive shunting of the junctions. Strongly coupled cells show synchronization even for large parameter splitting. Finally, a study of the behavior under external microwave radiation shows that the frequency locking-range becomes strongly flux-dependent, whereas the locking frequency itself turns out to be flux-independent.Comment: 26 pages, REVTEX, 9 PS figures appended in uuencoded form at the end, submitted to Phys. Rev. B