Fracture Volume Research Articles

Influence of thermo-mechanical aging on fracture resistance and wear of digitally standardized chairside computer-aided-designed/computer-assisted-manufactured restorations

ObjectivesTo investigate the influence of thermal cycling and mechanical loading (TCML) aging on fracture resistance and wear behavior of various chairside computer-aided-designed/computer-assisted-manufactured (CAD/CAM) premolar crowns cemented on standardized tooth abutments. MethodsEighty chairside CAD/CAM crowns were prepared using lithium disilicate (IPS e.max CAD; EM), zirconia-infiltrated lithium silicate (Celtra Duo; CD), polymer-infiltrated ceramic network (Vita Enamic; VE), and resin nanoceramics (Cerasmart; CS) (n = 20). The specimens were divided into two groups (n = 10). In one group, they were subjected to TCML: thermocycling (6000 cycles in distilled water at 5–55 °C) and mechanical loading (50 N for 1.2 × 106 cycles), while in control group they were stored in distilled water (37 °C for 24 h). The fracture load, height loss, and volume wear of the crowns were measured after TCML. Fractography was performed on fractured specimens. Data were analyzed using analysis of variance and multiple comparison tests (α=0.05). ResultsThe mean fracture loads of EM and CD were significantly higher than those of EC and CS (p<0.05). There was no significant change in the fracture load of any CAD/CAM crowns after TCML (p>0.05). CS exhibited a significantly higher volume wear than the other materials investigated. The wear tracts of all TCML crowns acted as failure origins during the fracture test. ConclusionsThe fracture resistance of glass-ceramic CAD/CAM crowns was significantly higher than that of resin composite crowns. A 5-year TCML aging did not affect the fracture resistance of CAD/CAM crowns investigated. However, TCML treatment produces a larger wear track in CS than in other materials. Clinical SignificanceAppropriate chairside CAD/CAM restorative material should be selected for successful clinical practice after considering the fracture and wear resistance of the crowns.

Semianalytical Model for Monitoring Fracture Liquid-Loading in Vertical Fractured Gas Wells

Summary Liquid loading seriously affects gas wells production and even causes gas wells abandonment. Many researchers still focus on correcting a critical liquid-loading flow rate to alleviate these problems. However, they still cannot reasonably be explained. Gas flow rate is higher than the critical liquid-loading flow rate, but liquid loading can still occur. Therefore, until an accurate critical fluid-loading flow rate is discovered, we should monitor the fluid-loading phenomenon to prevent it from affecting production gas wells’ performance. In this work, a fracture liquid-loading monitoring (FLLM) model is proposed and solved for the timely monitoring of fracture liquid-loading (FLL) positions and volume. The Newman product and Green function methods are used to develop and solve the FLLM model. The fracture is discretized into 2nxnz grids to describe an FLL volume and position. The numerical simulation method is used to verify the accuracy of the FLLM model. As a result, four innovative flow regimes, including fracture cavity liquid-loading flow, fracture root liquid-loading flow, transitional flow considering fracture cavity liquid-loading flow, and transitional flow considering fracture root liquid-loading flow, are identified on the pressure response curves. The pressure response of the same gas well at different times is well matched by the model in this paper, and the obtained parameters are more reasonable. The FLLM model can correct for magnified permeability, shortened half-length, and magnified wellbore storage coefficient. In conclusion, the FLLM model is established to monitor FLL, and alert engineers to remove liquid loading on time to prevent water from suddenly rushing into a wellbore and causing gas wells abandonment.

Space distribution of the seismic source energy between 1-1-2000 and 3-7-2022 at Campi Flegrei caldera

The spatial distribution of seismic sources is commonly visualized through location maps, where a symbol (commonly a dot or a cross) shows where the earthquake source is located inside the area under study. In the present note I propose a different visualization approach, based on the isoline representation of the Energy Space Density (ESD), which is conceptually similar to approaches already used in literature to represent the pattern of space distribution of strong earthquakes or to spatially identify earthquake swarms. Visualizing such a pattern jointly with the hypocentral distribution map, favors the conceptual association of the Seismic Energy Release to the known geological structures in the area. A test is carried out using the Campi Flegrei seismic catalogue between 2000 and, 2022, period in which the seismic activity in the area resumed after a long calm of several years. The catalogue reports >4000 seismic events with magnitude ranging from 0.5 to 3.5, all located inside a very small volume (5 × 5 × 5 km) and associated with the phenomenon called ”bradiseism”, a slow but intense ground uplift (>80 cm in the 22-year interval spanned by the catalogue). Results indicate that the ESD pattern enhances the visualization of the rock fracture density associated with the ground deformation, in agreement with other studies in the same area, producing a picture of the most fractured rock volumes, possibly associated with fluid storage under the active areas of Solfatara and Pisciarelli.

Multi-dimensional non-uniform deformation and failure of siltstone determined using acoustic, 3D-digital image correlation, and computed tomography

Uniaxial compression tests monitored using linear variable differential transformers (LVDTs), digital image correlation (DIC), computed tomography (CT), acoustic emission (AE), and ultrasonic velocity were utilized to study the multi-dimensional non-uniform deformation and failure characteristics of siltstone. Under one-dimensional (1D) conditions, the characteristic stress of the siltstone was determined by the AE counts, ultrasonic velocity, and volumetric strain measured by the extensometer. Under two-dimensional (2D) conditions, zonal disintegration was observed on the apparent fracture of the siltstone specimen. The crack nucleation process, stress release characteristics, and crack type were analyzed in the “broken area,” “penetrating crack area,” and “non-penetrating crack area” under different characteristic stress states. Subsequently, the evolution of the non-uniformity coefficient of the 2D strain field with the 1D characteristic stress was established. Under three-dimensional (3D) conditions, the fracture size of the siltstone was divided according to the equivalent length of fracture volume, and the spatial distributions of macro-, meso-, and microfractures were analyzed. The siltstone 3D zonal disintegration phenomenon was further quantitatively described by calculating the fractal dimensions of fractures in different radius ranges. Finally, the AE source localization method was improved by modifying the wave velocity. The transformation of the primary and secondary bearing areas in different stress stages was revealed based on the spatio-temporal evolution of the AE sources with different energy levels.

Exploring the role of the structural heterogeneity of fractured carbonate reservoirs in contact with dissolved CO2 based on fracture-water-rock simulation experiments

Based on the geological background of ultra-deep fractured carbonate reservoirs in the Shunbei oil and gas field, the objective of this study was to clarify the interactions between fractured carbonate reservoirs and formation fluids (brine with dissolved CO2) under deep strata, and the potential impact of these interactions on reservoirs. In this study, high-temperature and high-pressure simulation experiments and numerical simulations based on the Yijianfang Formation in the Shunbei area were designed to investigate the influence of temperature, pressure, fluid, and structural heterogeneity on fluid transport and mass transfer, calculate the ion diffusion characteristics and the trend of mineral dissolution/precipitation along the fractures, and clarify the change in the reservoir space. The results indicated that the volume of the main fracture increased after the reaction between an acidic solution and a formation sample, the permeability of the sample increased by orders of magnitude, and its porosity increased accordingly. The overall reaction during the experimental period was dominated by the dissolution of calcium carbonate, and no calcium carbonate precipitated. The structural heterogeneity and hydraulic properties of the sample make the main flow channel a main fracture. The flow and reaction processes in the flow channel promoted each other. The effects of temperature and pressure on the overall reservoir space were insignificant. Branch fractures or microfractures can weaken the main fluid flow rate and tend to result in the accumulation of solutes, the ends of which may be potential locations for mineral precipitation. Therefore, the priority exploration location for deep and ultra-deep fractured reservoirs should be the main fractures upstream of the fluid flow.

3D anisotropy in shear failure of a typical shale

It is inadequate to study the shear failure anisotropy of shale in only 2D space. Aiming at a 3D analysis, a series of direct shear tests was conducted on Longmaxi shale with three typical bedding orientations: arrester, divider and short-transverse orientations. During testing, acoustic emission (AE) and digital image correlation (DIC) techniques were simultaneously employed to monitor failure development, after testing, X-ray computed tomography (CT) scanning was adopted to acquire and reconstruct the fractures inside typical ruptured samples for more detailed analysis. The results indicated that the shear strength parameters exhibited 3D anisotropies and those of the arrester sample did not have equivalent shear strength parameters to the shale matrix. The maximum (minimum) shear strength and cohesion were obtained with the divider (short-transverse) orientation, and the internal friction angle reached its maximum (minimum) with the divider (arrester) orientation. Combining the AE, DIC and CT techniques, four characteristic stress levels that can capture the progressive shear failure process of shale rocks were identified, and the onset and accelerated development of shear damage-induced dilation were observed at the crack initiation and coalesce stress thresholds, respectively. During the crack coalescence stage, the dominated microcracking mechanism transferred from tensile-mode to shear-mode. For the arrester and divider orientations, more tensile-mode AE events were generated due to the microcracking along the vertical beddings. Compared with the divider samples, a more complex fracture network with a larger fracture area and volume was obtained in the arrester samples, whose strengths were smaller.

Simulation Study for Hydraulic Fracture Monitoring Based on Electromagnetic Detection Technology

The stimulated reservoir volume (SRV) technology extends conventional fracturing technology. Understanding how to effectively and accurately determine modified fracture shape and volume is the key point to evaluating the stimulation effect. Using electromagnetic detection technology can provide a new option for measuring these parameters. By the finite method, the rationality of electromagnetic detection technology to obtain the relevant parameters of reconstruction fracture is testified through forward simulation. This study compared the signals of fractures with different conductivity, volume, and shape collected by electromagnetic detection tool, and the results show that the signals have a specific correspondence with fracture geometric parameters. According to the electromagnetic signal curve of the forward model, the description of propped fractures, including positions and sizes, can be realized.

Experimental investigation on fracture characteristics by liquid nitrogen compound fracturing in coal

The stimulation efficiency of hydraulic fracturing in coalbed methane (CBM) reservoir are low due to high filtration. In this study, a new compound fracturing method is proposed to improve the CBM reservoir fracturing efficiency combining the advantages of liquid nitrogen (LN2) fracturing and hydraulic fracturing. The compound fracturing starts from LN2 fracturing forming complex fractures and non-filtration zones, follows by injecting nitrogen gas (N2) to displace LN2 near the borehole into the fracture tips and prevent subsequent sand-carrying fluids from freezing in the borehole, and finishes by using sand-fluid mixtures carrying proppant into the frozen coal seam. To test the feasibility, fracturing experiments were conducted to investigate the performances of LN2 compound fracturing. The lab results show that LN2 compound fracturing can create more complex and highly conductive fracture networks than water fracturing and pure LN2 fracturing. Compared with LN2 fracturing, the average fracture aperture, fractures number, and total fracture volume induced by compound fracturing increased by 28%, 10%, and 34%, respectively. Compared with water fracturing, the fractures number, and total fracture volume induced by compound fracturing increased by 55% and 42%, respectively. The reason for the improved conductivity as follows: in the pad stage of the compound fracturing, coal is fractured by LN2 with low viscosity and low temperature, forming a large number of small-scale fractures. In the slurry stage, coal is fractured by water, which further activates the small-scale fractures, increasing the number and aperture of fractures. The key findings obtained in this work is the proposed LN2 compound fracturing method that helps sustainable development of CBM resources in an efficient and environmentally friendly way.

Study on Local Brittleness of Rock Based on Multiple Linear Regression Method: Case Study of Shahejie Formation

Rock brittleness index is an important parameter that affects the volume fracturing effect of an unconventional reservoir. The higher the brittleness index, the larger the communication area of fracture network formed under volume fracturing. However, rock brittleness has strong heterogeneity, which seriously affects the propagation of volume fracture network. Most existing rock brittleness characterization methods start from macro brittleness and cannot analyze the influence of heterogeneity on reservoir brittleness. The mineral composition analysis method can characterize the heterogeneity of a reservoir by analyzing the influence of mineral composition on brittleness, but this is limited to qualitative analysis on different minerals, resulting in large errors. In this study, the relationship between macro mechanical properties and micro mineral composition of rocks was analyzed using multiple linear regression analysis and a large number of experimental core parameters on the Shahejie Formation to understand the quantitative characterization of rock brittleness distribution in a heterogeneous reservoir. The results showed that quartz, plagioclase, analcite, siderite, and pyrite were high brittle minerals while clay minerals were low brittle minerals. This method provides a new focus for the analysis of brittle distribution of heterogeneous reservoirs and an additional method to study rock fracture law.

Acute Pelvic and Hip Apophyseal Avulsion Fractures in Adolescents: A Summary of 719 Cases.

Apophyseal avulsion fractures of the pelvis and hip are common injuries in adolescent athletes. However, high volume comparative studies elucidating the spectrum of injuries are largely absent from the literature. The current study provides a comprehensive analysis of demographic, anatomic, pathophysiological, clinical, and athletic-related variables associated with such injuries in an extensive population of affected adolescents. A retrospective review was performed of records of patients presenting to a single tertiary care pediatric hospital between January 1, 2005, and July 31, 2020, collecting variables including patient sex, age, body mass index, fracture location, injury mechanism, sport at the time of injury, and duration of prodromal symptoms. Seven hundred nineteen fractures were identified in 709 patients. The average patient age was 14.6, and 78% of the fractures occurred in male patients. The anterior inferior iliac spine (33.4%), anterior superior iliac spine (30.5%), and ischial tuberosity (19.4%) were the most common fracture sites. The most common injury mechanisms were running (27.8%), kicking (26.7%), and falls (8.8%). The most common sports at the time of injury were soccer (38.1%), football (11.2%), and baseball (10.5%). Fracture site was significantly associated with patient sex, age, body mass index, laterality, mechanism, sport, time from injury, and presence of prodromal symptoms. The annual volume of pelvic avulsion fractures treated at the institution increased significantly from n=17 in 2005 to n=75 in 2019. Adolescent pelvic and hip avulsion fractures occur during a narrow window of age and skeletal maturation and are frequently sustained during sporting activities. Each fracture location is associated with certain demographic, mechanistic, and patient-specific characteristics. The associations between fracture site and patient-specific or injury-specific variables offer insights into the pathophysiology and possible underlying biomechanical risk factors that contribute to these injuries. This is a level III retrospective study.

Prediction of Enophthalmos in Medial Orbital Wall Fracture: Suggested Coordinate Plane for Making Surgical Decisions.

Enophthalmos is one of the most distressing complications of blowout orbital fractures. Although several studies have been conducted on the topic of indications of early surgical correction, none have been performed using a set of measurable parameters. The study quantitatively examined orbital fracture areas (OFA) and volumes (OFV) retrospectively of 242 patients with isolated medial orbital wall fractures that were treated conservatively during a 12-year period (from 2009 to 2021). Three plastic surgeons measured enophthalmos >6 months after trauma. The correlations between parameters and enophthalmos in the study cohort were analyzed. In addition, patients treated operatively, and nonoperatively were compared with assess the suitability of the predictive model. Significant correlations were observed between several parameters and late enophthalmos. Total 2.59cm 2 of OFA (ie, OFA >2.59cm 2 ) or 1.45cm 3 of OFV (ie, OFV >1.45cm 3 ) corresponds to 2mm of enophthalmos. Multiple regression analysis revealed the following coefficients: -0.208 is a constant ( P <0.001), with 0.695 and 0.372 for OFA and OFV, respectively ( P <0.001 for both OFA and OFV). The study shows that enophthalmos can be more accurately predicted when OFA and OFV are simultaneously considered in patients with isolated medial wall fractures. Finally, an algorithm and a "blowout fracture coordinate plane" was proposed to aid treatment decision-making in isolated medial wall fractures.

Effect of Content and Length of Polypropylene Fibers on Strength and Microstructure of Cementitious Tailings-Waste Rock Fill

The mechanical strength properties of cemented tailings backfill are very important for the safe and environmentally friendly mining of mineral resources. To check the impact of polypropylene fiber on strength and microstructure of cementitious tailings waste rock fill (CTWRF), diverse fiber lengths (6 and 12 mm) and dosages (0-control specimen, 0.3, 0.6, and 0.9 wt.%) were considered to prepare fiber-reinforced CTWRF (FRCTWRF) matrices. Experiments such as UCS (uniaxial compressive strength), X-ray CT (computed tomography), and SEM (scanning electron microscopy) were implemented to better characterize the backfills studied. Results showed that UCS performance of FRCTWRF was the highest (0.93 MPa) value at 6 mm fiber long and 0.6 wt.% fiber content. The peak strain of FRCTWRF was the highest (2.88%) at 12 mm fiber long and 0.3 wt.% fiber content. Growing the length of fiber within FRCTWRF can reduce its fracture volume, enhancing the crack resistance of FRCTWRF. Fiber and FRCTWRF are closely linked to each other by the products of cement hydration. The findings of this work will offer the efficient use of FRCTWRF in mining practice, presenting diverse perspectives for mine operators and owners, since this newly formed cementitious fill quickens the strengths required for stope backfilling.

Experimental study on fracture characteristics of coal due to liquid nitrogen fracturing

Liquid nitrogen (LN2) fracturing is expected to become an effective means of increasing coalbed methane production due to good reservoir adaptability. Advantages of the technology are the ultra-low temperature and huge gasification pressure during the fracturing, but how to give full play to the advantages of liquid nitrogen fracturing needs further exploration. In this paper, the fracture pressure, fracture degree, roughness of fracture surface and microstructure change of coal after LN2 fracturing are analyzed under different under experimental conditions, and the main factors affecting LN2 fracturing are discussed in combination with the numerical simulation results. The results show that the temperature rise and freeze–thaw treatment can effectively reduce the initiation fracture pressure of coal, with a decrease of more than 40%; The fracture degree and roughness of coal increase, especially the volume fracture of the freeze–thaw coal sample is the largest, and the cross-sectional area expansion rate (roughness index Sdr) increases as high as 325%. In addition, the SEM scanning results showed that the heating and freezing thawing treatment promoted the intergranular and transgranular destruction of the coal. Numerical analysis shows that temperature rise and freeze–thaw treatment can expand initial damage range around the borehole of LN2 fracturing instant, thereby promoting gas permeability efficiency, increasing pore pressure and improving the fracturing effect of coal. The temperature rise enhances the expansion effect of LN2 gasification, and the freeze–thaw treatment can give the full play to the low-temperature damage effect of LN2. Based on this, an improved technology of LN2 fracturing is put forward: Technology of fracturing and permeability enhancement with liquid nitrogen coupled high temperature.

Experimental study on mechanical properties and fracture characteristics of shale layered samples with different mineral components under cyclic loading

In shale plays, the in-situ effective stress is continuously being perturbed because of the production which impacts field operations. Therefore, mechanical properties of the formation and its response to stress field changes, with respect to mineral variations, is of great significance for the proper design of horizontal drilling and hydraulic fracturing. In this paper, clay-rich, calcareous and siliceous black shales are classified based on their XRD analysis, from the Wufeng and Longmaxi Formations in the Sichuan Basin of the Upper Yangtze Plate. Uniaxial quasi-static and cyclic loading tests, acoustic emissions, and CT scanning are combined to study mechanical behavior and fracturing mechanisms of the shale layer samples that own different mineral components. The results show that the strength and deformation response of the samples is a function of their mineral composition. The damage from cyclic loading is gradually accumulated in the samples which ultimately leads to fatigue and sample failure. The compressive strength of the samples under cyclic loading is lower than in the uniaxial quasi-static conditions. Furthermore, the fracturing of rock under uniaxial quasi-static loading mainly occurs after the peak strength is achieved while in cyclic loading, when a certain stress level is reached, fracturing begins, the damage accumulates up to the peak stress and the rock suddenly fails. Based on CT images from the samples after rupture, failure modes of the clay-rich, calcareous and siliceous black shales mainly constitute extensional and shear fractures, with some conjugate shearing. In comparison with uniaxial quasi-static loading, the fracture volume of the clay-rich, calcareous and siliceous black shales after cyclic loading increases by 12.2%, 25.9% and 32.9%, respectively. Overall, this study explains how cyclic loading that can be applied in the field via changing the injection pressure and other stimulation parameters, can effectively improve the complexity of the shale fracture network and lead to higher productivity of the formation.

Relationship between the heterogeneity of low-permeability reservoirs and the dynamic evolution of fractures under uniaxial compression conditions by CT scanning: A case study in the jiyang depression of Bohai Bay Basin, China

Based on an analysis of core fractures and computed tomography scanning by X-ray under uniaxial compression tests with loading and unloading, this study investigated the three-dimensional evolution of fracture initiation and propagation in different heterogeneity conditions of low-permeability reservoirs. Reservoir heterogeneity affected the 3D dynamic development of fractures. With increasing loading value, fractures with strong heterogeneity in low-permeability reservoirs followed the development sequence from shallow to deep depth in the profile. When the fracture tip reached the incompetent layer, propagation stopped. Subsequently, when the deformation continued to increase, the fracture crossed the incompetent layer and initiated a new fracture at the front end. Therefore, the across-bedding and through-going macro fractures formed in conjugate sets or were Y-shaped, with roughly equal spacing. In the plane, the fractures initiated along the pre-existing bedding parallel fracture and further propagated into large fractures. Consequently, they formed a net-shaped fracture from the edge to the center, with a long development period. These fractures intersected to form a complex, interconnected, and high-fracture-density system in three dimensions. Under the same loading value, owing to uniform lithology, the formation of micro-fractures in the weak heterogeneity of low-permeability reservoirs is difficult. Furthermore, long shear fractures were only produced in a relatively short formation period with a low fracture density. In the plane, the fractures stepped in an en-énchelon and terminated with horse-tailing microfractures. Moreover, the strong heterogeneity of low-permeability reservoirs was more favorable for producing fractures. The fracture volume was 13.17% of the total sample volume compared to 0.67% in the weak-heterogeneity reservoir under the same loading compression. Furthermore, a better fracturing effect was achieved by fracturing along the direction &amp;gt;50° with the natural fracture and under the condition of small differential horizontal stresses.

Strength attributes of fiber-reinforced lightweight aggregate concrete incorporating Lytag ceramsite under freeze-thaw environment

The property of high strength of lightweight aggregate concretes (LWACs) makes them widely applicable in construction. However, a low-temperature environment could accelerate the properties degradation of LWACs. In this paper, the effects of freeze-thaw cycles on the strength behavior of basalt fiber (BF) and polyacrylonitrile fiber (PANF) reinforced lightweight aggregate concrete with Industrial waste ceramsite-Lytag investigated, including cubic and axial compressive strength, splitting tensile strength, flexural strength, and shear strength. Mass loss, relative dynamic elastic modulus (RDEM), scanning electron microscopy (SEM), and computed tomography (CT) were used to analyze the impact of freeze-thaw damage on strength performance and microstructure. The results showed that BF and PANF incorporation significantly affected the residual strength due to their ability to suppress crack growth. The specimens with higher BF and PANF volume fracture had better freeze-thaw resistance properties. Moreover, BF-reinforced LWACs exhibited better freeze-thaw resistance than PANF-reinforced LWACs because BF has superior mechanical properties. The flexural strength indicated the fastest degradation rate after freeze-thaw cycles, while the RDEM revealed the least damage. The freeze-thaw resistance durability of fiber-reinforced LWACs is evaluated based on strength degradation, and the corresponding environment partition of specimens is produced. In order to estimate the strength behavior, the equal-damage strip calculation model is proposed by considering size and loading type effects. The comparison analysis of calculation and test results of strength after freeze-thaw cycles suggested applying the four-sides calculation model for predicting the strength behavior of LWACs.

An investigation of data analysis method for hydraulic fracturing based on the water hammer effect

Hydraulic fracturing plays a crucial role in the development of unconventional resources, and assessing fracture geometry is a fundamental aspect of hydraulic fracturing analysis. Among the various technologies for evaluating fracture geometry, the water percussion signal-based method has gained popularity due to its cost-effectiveness, convenience, and real-time capabilities. In this study, we present a methodology for analyzing fracture data that utilizes the water percussion effect. By leveraging the impact of fractures on water percussion pressure attenuation, we propose an inverse calculation approach to determine fracture geometry. Firstly, we introduce the RCI (Reservoir-Completion-Interaction) circuit model, which effectively addresses the bottom hole fracture boundary and simulates the variation of water percussion pressure in the wellbore. Secondly, the simulation results are utilized in an iterative process to determine the RCI values, which are then utilized for the inversion calculation of fracture geometry. Finally, we apply this method to a field case and compare the simulation results with microseismic monitoring data. A larger resistance (R) value indicates a smaller fracture volume, while the (C) value can be used to monitor any poorly performing stages of the fracturing simulation process. The (I) value primarily affects the parameter calculation of the fracture size, especially the fracture width. The results of the field application show that the accuracy rate exceeding 80%, validating the reliability of the model and providing a valuable reference for field fracturing data analysis.

Finite Element Analysis of Acetabulum Prosthesis' Lining Damage Zone with Different Implanting Angle.

Research the acetabular component's construction method of a three-dimensional finite element model in THA with different angles and study the influence of polyethylene liner wearing with finite element analysis. Build a model in the 3D modeling software system HyperMesh according to the artificial hip joint prosthesis' entities and data. Using a finite element analysis system, ABAQUS 6.11 reconstitute acetabular prosthesis after hip replacement joints under different implanting position angles. Simulation and load the joint load when sheet foot touchdown state. Calculate the plastic volume strain and fatigue fracture. The two groups of combinations of abduction angle 50° vs. anteversion angle 10° and abduction angle 55° vs. anteversion angle 15° have been found to have relatively smaller interface plastic strain and fatigue fracture volume value (2.241 × 10-7 m3, 2.443 × 10-7 m3), respectively. The groups of combinations of abduction angle 50° vs. anteversion angle 10° have been found to have relatively smallest interface plastic strain and fatigue fracture volume value in the total hip arthroplasty.

3D natural fracture model of shale reservoir based on petrophysical characterization

The existence and distribution of natural fractures in shale reservoirs is of great significance to shale gas exploitation. A 3D fracture spatial distribution model with varying reservoir burial depth and regional tectonicsin southeastern Chongqing is constructed based on an enhanced DFN modeling method. Fracture volume density (P32) is calculated by petrophysical test and verified from test wells. The geometric parameters of fractures (length, occurrence, opening) are clustered by regional tectonics. Uncertainties are considered by a stochastic description of the fracture network geometry, utilizing Monte Carlo simulation techniques. The application of the model in seven wells and the quantitative analysis of the relationship between fracture density and burial depth allow the modeling to be extended to deep and ultra-deep reservoirs. Fracture models with reservoirs buried depth over 3000 m are predicted and analyzed. For the various input parameters, the influence of model size and fracture shape on model reliability is analyzed. The establishment of fracture model can effectively quantitatively characterize the reservoir fracture distribution at different burial depths, and its efficient implementation in finite element software can provide support for shale gas mining engineering.

High-viscosity versus low-viscosity cement for the treatment of vertebral compression fractures: A meta-analysis of randomized controlled trials.

High viscosity cement (HVC) and low viscosity cement (LVC) have been used to treat osteoporotic vertebral compression fractures (OVCFs). Our study was to assess the safety and efficacy of HVC and LVC in treating OVCFs. We searched the electronic database for randomized controlled trials of HVC and LVC to treat OVCFs. Random-effects model was performed to pool the outcomes about operation time, visual analogue scale (VAS), bone cement injection volume, oswestry disability index (ODI), bone cement leakage and adjacent vertebral fractures. Twelve randomized trials were included in the meta-analysis. The 2 groups had similar changes in terms of bone cement injection volume, ODI and adjacent vertebral fractures. The HVC group showed shorter operation time and better VAS score improvement. The bone cement leakage rate of the HVC group was significantly better than LVC group (P < .00001).According to the location of bone cement leakage, in the leakages of the veins (P < .00001), the intervertebral disc (P < .00001), the paravertebral area (P = .003) and the intraspinal space (P = .03), the HVC group were significantly better than the LVC group. In terms of bone cement injection volume, ODI and adjacent vertebral fractures, the 2 group are equivalent. HVC had a shorter operation time, lower bone cement leakage rate and better VAS score improvement, compared with LVC.