Intelligent spacing selection model under energy-saving constraints for the selection of communication nodes in the Internet of Things

Current IoT communication node spacing selection process show may potential areas for improvements such as high delay ratio, high total energy consumption ratio, confusion of the optimal communication information band, intelligent spacing node design under the constraints of the energy-saving selection of IoT communication. Based on energy-saving constraints, the link status between nodes is evaluated through link stability and link quality. In order to prevent the generation of serious noisy nodes and frequency hopping data, the interference nodes under the intrusion of the Internet of Things are identified by determining transition amplitude of the noise nodes in the transmission data sequence. Finally, according to the calculation results of the optimal communication node selection, the design of the intelligent spacing selection model for the communication nodes of the Internet of Things is realized. The simulation results show that the established model not only reduces energy consumption of nodes, shortens the average transmission delay of nodes, but also improves anti-interference effect of node spacing selection.

Semianalytical Model for Fault Slippage Resulting from Partial Pressurization

Summary Casing failure in shale gas wells has seriously impacted production from Weiyuan and Changning fields in Sichuan Province, China. Linearly distributed microseismic data and the corresponding casing shear deformation close to these microseismic signals indicate fault reactivation in these areas during hydraulic-fracturing treatments. Apparently, interaction of hydraulic fractures with nearby faults causes fault slippage, which in some situations has led to well shearing. Hence, we propose a semianalytical model in this paper to estimate the length of slippage along the fault that is caused by pressurization of a fault intercepted by the hydraulic fracture. These calculations have been performed for different configurations of the fault with respect to the hydraulic fracture and principal stresses. Using the semianalytical model provided in this paper, two fault slippage cases are calculated to assess the casing failure in nearby wells. In one case study, the calculated results of the fault slippage are consistent with the scale of casing deformation in that well and a microseismic magnitude caused by fault slippage is calculated that is larger than the detected events. The presented model will provide a tool for a quick estimation of the magnitude of fault slippage upon intersection with a hydraulic fracture, to avoid potential casing failures and obtain a more reliable spacing selection in the wells intersecting faults.

The Influence of Pebble Placement on the Wake of Tandem Pebbles in a Free Stream

The effect, the pebble spacing has, on the fluid flow past two spheres in a free stream, was investigated by utilizing Direct Numerical Simulation (DNS), a Spectral Element Method (SEM) and NEK5000. There was seen that for a spacing of 2 pebble diameters (D), between the centroids, the turbulence statistics were asymmetric. For this study four different pebble spacings were investigated: 1.5D, 2.0D, 2.5LD, 3.0D. For all the cases the inlet flow, (U0) was selected that the Reynolds number, (Re) equalled 1000. The flow was allowed to develop for 200 Convective Units (CU = D/U0) before tests were conducted to ensure compliance to DNS. With the Kolmogorov scales captured and adequate Y+ values, time averaging was done for 800 CU to calculate the turbulence statistics. Calculated parameters include turbulence statists for selected line profiles and turbulent kinetic energy (TKE) budget terms. The generated statistics will be compared for each spacing selection.

Tilted Dendritic Growth Dynamics and Dendrite to Degenerate Seaweed Transition in Directional Solidification: Insights from Phase-Field Simulations

In this paper, we review our results from phase field simulations of tilted dendritic growth dynamics and dendrite to seaweed transition in directional solidification of a dilute alloy. We focus on growth direction selection, stability range and primary spacing selection, and degenerate seaweed-to-tilted dendrite transition in directional solidification of non-axially orientated crystals. For growth direction selection, the DGP law (Phys. Rev. E, 78 (2008) 011605) was modified through take the anisotropic strength and pulling velocity into account. We confirm that the DGP law is only validated in lower pulling velocity. For the stability range and primary spacing selection, we found that the lower limit of primary spacing is irrelative to the misorientation angle but the upper limit is nonlinear with respect to the misorientation angle. Moreover, predicted results confirm that the power law relationship with the orientation correction by Gandin et al. (Metall. Mater. Trans. A. 27A (1996) 2727-2739) should be a universal scaling law for primary spacing selection. For the seaweed-to-dendrite transition, we found that the tip-splitting instability in degenerate seaweed growth dynamics is related to the M-S instability dynamics, and this transition originates from the compromise in competition between two dominant mechanisms, i.e., the macroscopic thermal field and the microscopic interfacial energy anisotropy.

Solidification of Bulk Lamellar Eutectics

Eutectic alloys from the ternary system Al-Cu-Ag are excellent model alloys for the investigation of coupled eutectic growth, not only because most materials properties are well known but also because the system offers a rich variety of crystal structures and crystal orientation relationships (ORs) being associated to distinct minima of the solid-solid interface energy. This paper describes three research topics specifically related to bulk lamellar Al-Al2Cu eutectics, e.g. the maze-to-lamellar transition during early growth, the role of fault lines during lamellar spacing selection close to the pinch-off limit and the onset of eutectic cell formation above the constitutional supercooling limit. These topics are central to the microgravity experiments SETA presently being prepared for the MSL / SQF.