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Computational modeling of the initiation and propagation of complex fracture is central to the discipline of engineering fracture mechanics. This review focuses on two promising approaches: phase-field (PF) and peridynamic (PD) models applied to this class of problems. The basic concepts consisting of constitutive models, failure criteria, discretization schemes, and numerical analysis are briefly summarized for both models. Validation against experimental data is essential for all computational methods to demonstrate predictive accuracy. To that end, the Sandia Fracture Challenge and similar experimental data sets where both models could be benchmarked against are showcased. Emphasis is made to converge on common metrics for the evaluation of these two fracture modeling approaches. Both PD and PF models are assessed in terms of their computational effort and predictive capabilities, with their relative advantages and challenges are summarized.

Compaction and sand migration are important problems in loosely consolidated and unconsolidated high-rate gas reservoirs, and proppants in the hydraulic fractures. Their impacts on permeability and non-Darcy flow are important for accurate estimation of well productivity. In this paper, we quantified changes in flow parameters due to simulated compaction and sand migration for computer-generated sphere packing and presented the results in the context of correlations for permeability and non-Darcy coefficient that can be used in reservoir simulations. Compaction effects were simulated by increasing grain diameter in a sphere packing. Permeability and non-Darcy coefficients were calculated using the lattice Boltzmann method (LBM). Findings indicated that the permeability decrease was not directional for compaction simulated by simple grain growth and the change in permeability could be estimated from the porosity change with a power-law relation with an exponent equal to 3.28. An analogous power-law relation between non-Darcy coefficient and permeability was found with the exponent equal to − 1.32. For reservoirs that undergo these compaction-like processes during production, estimation of the inertial effects from traditional correlations developed as a function of permeability and porosity may lead to underestimation of the inertial effects. Sand migration causes pore-throat plugging, which leads to significant permeability reduction. We simulated sand particle-plugged pore-throat locations from network simulations for different values of pore volume reduction, and the corresponding permeability and non-Darcy coefficients were calculated from LBM. It was found that permeability change from sand plugging was directional; permeability decrease in the flow direction was approximately double the other directions. A power-law relation between permeability and porosity could be used to estimate the permeability with a much larger exponent: approximately 10 in the flow direction in the range of plugging studied in this work. Because porosity reduction can depend on other factors besides pore-throat plugging (e.g., compaction or pore surface deposition), a correlation was developed to estimate permeability dependence on the pore-throat sand concentration. Even though permeability change was directional, the permeability and non-Darcy coefficient trends collapsed onto a single power-law relation. The exponent on a power-law relation was greater in magnitude (approximately − 1.84) compared to compaction.

ln this paper, performance of solar photovoltaic power system using State Vector Pulse Width Modulation technique is studied. As we know the solar photovoltaic power generation is getting a wide attention because of its clean and renewable energy, which is the need of the hour to use as an alternate to the conventional energy. However, the power produced by solar PV system contains some power quality problems such as low output voltage, harmonics, ripples, and poor power factor. SVPWM techniques can be applied to reduce such problems. Such methods will be studied in this paper of solar PV power generation containing boost converter.

We report the strategy of anesthesia and intraoperative neurophysiological monitoring (IONM) in a 29-year-old, 22 weeks pregnant patient posted for surgery for aggressive vertebral body hemangioma. We used propofol and fentanyl-based anesthesia for IONM. Motor-evoked potentials (MEP) and somatosensory-evoked potentials (SSEP) were used to monitor the neural tracts during surgery. Fetal heart rate monitoring was done preoperatively and postoperatively. Train of 8, 75 μs duration pulse, 250-500 Hz stimulus was used for MEP and 30 mA, 200-400 μs, 3-5 Hz was used for SSEP. No new motor or somatosensory deficits appeared. Our findings suggest that IONM can be safely done in pregnant women.

A 15-year-old boy diagnosed as case of cervical kyphosis, atlantoaxial dislocation, and hypofibrinogenemia was posted for corrective surgery under general anesthesia. His preoperative plasma fibrinogen levels and other coagulation profile were deranged. He was diagnosed with type 1 congenital fibrinogen abnormality, that is, hypofibrinogenemia. Preoperative blood products including cryoprecipitates were transfused to correct fibrinogen levels and coagulation profile. Cryoprecipitate was transfused at the dose of 1 bag per 10kg body weight per day. During intraoperative period, blood products were transfused following blood loss of 1100mL. Postoperatively the repeat laboratory investigations after 20 h revealed normal PF levels (211 mg/dL) with normal coagulation profile. He was discharged five days later with the uncomplicated postoperative course.