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Sample records for volume fracture length

  1. Effects of fracture distribution and length scale on the equivalent continuum elastic compliance of fractured rock masses

    Institute of Scientific and Technical Information of China (English)

    Marte Gutierrez; Dong-Joon Youn

    2015-01-01

    Fracture systems have strong influence on the overall mechanical behavior of fractured rock masses due to their relatively lower stiffness and shear strength than those of the rock matrix. Understanding the effects of fracture geometrical distribution, such as length, spacing, persistence and orientation, is important for quantifying the mechanical behavior of fractured rock masses. The relation between fracture geometry and the mechanical characteristics of the fractured rock mass is complicated due to the fact that the fracture geometry and mechanical behaviors of fractured rock mass are strongly dependent on the length scale. In this paper, a comprehensive study was conducted to determine the effects of fracture distribution on the equivalent continuum elastic compliance of fractured rock masses over a wide range of fracture lengths. To account for the stochastic nature of fracture distributions, three different simulation techniques involving Oda’s elastic compliance tensor, Monte Carlo simulation (MCS), and suitable probability density functions (PDFs) were employed to represent the elastic compliance of fractured rock masses. To yield geologically realistic results, parameters for defining fracture distribu-tions were obtained from different geological fields. The influence of the key fracture parameters and their relations to the overall elastic behavior of the fractured rock mass were studied and discussed. A detailed study was also carried out to investigate the validity of the use of a representative element volume (REV) in the equivalent continuum representation of fractured rock masses. A criterion was also proposed to determine the appropriate REV given the fracture distribution of the rock mass.

  2. Effects of fracture distribution and length scale on the equivalent continuum elastic compliance of fractured rock masses

    Directory of Open Access Journals (Sweden)

    Marte Gutierrez

    2015-12-01

    Full Text Available Fracture systems have strong influence on the overall mechanical behavior of fractured rock masses due to their relatively lower stiffness and shear strength than those of the rock matrix. Understanding the effects of fracture geometrical distribution, such as length, spacing, persistence and orientation, is important for quantifying the mechanical behavior of fractured rock masses. The relation between fracture geometry and the mechanical characteristics of the fractured rock mass is complicated due to the fact that the fracture geometry and mechanical behaviors of fractured rock mass are strongly dependent on the length scale. In this paper, a comprehensive study was conducted to determine the effects of fracture distribution on the equivalent continuum elastic compliance of fractured rock masses over a wide range of fracture lengths. To account for the stochastic nature of fracture distributions, three different simulation techniques involving Oda's elastic compliance tensor, Monte Carlo simulation (MCS, and suitable probability density functions (PDFs were employed to represent the elastic compliance of fractured rock masses. To yield geologically realistic results, parameters for defining fracture distributions were obtained from different geological fields. The influence of the key fracture parameters and their relations to the overall elastic behavior of the fractured rock mass were studied and discussed. A detailed study was also carried out to investigate the validity of the use of a representative element volume (REV in the equivalent continuum representation of fractured rock masses. A criterion was also proposed to determine the appropriate REV given the fracture distribution of the rock mass.

  3. Permeability tensor and representative elementary volume of fractured rock masses

    Science.gov (United States)

    Rong, Guan; Peng, Jun; Wang, Xiaojiang; Liu, Guang; Hou, Di

    2013-11-01

    Based on a simulation of three-dimensional fracture networks and a superposition principle of liquid dissipation energy for fractured rock masses, a model of the fracture permeability tensor is proposed. An elastic constitutive model of rock fractures, considering fracture closure and dilation during shearing, is also proposed, based on the dilation angle of the fracture. Algorithms of flow-path searching and calculation of the effective flow coefficients for fracture networks are presented, together with a discussion on the influence of geometric parameters of the fractures (trace length, spacing, aperture, orientation and the number of fracture sets) on magnitude, anisotropy of hydraulic permeability and the size of a representative elementary volume (REV). The anisotropy of hydraulic permeability of fractured rock masses is mainly affected by orientation and the number of fracture sets, and the REV size is mainly influenced by trace length, spacing and the number of fracture sets. The results of studies on REV size and the influence of in-situ stress on hydraulic conductivity of the rock mass on the slope of Jinping-I hydropower station, China, are presented using the developed models and methods. The simulation results agreed well with the results obtained from field water-pressure measurements, with an error of less than 10 %.

  4. Influence of fracture heterogeneity and wing length on the response of vertically fractured wells

    Energy Technology Data Exchange (ETDEWEB)

    Bennett, C.O.; Raghavan, R.; Reynolds, A.C.; Rosato, N.D.

    1983-04-01

    A finite-conductivity vertical fracture intersecting a well produced at a constant rate or at a constant pressure is considered. The pressure (or rate) response is obtained from a numerical model. Two aspects of this problem are considered: variable fracture conductivity and unequal fracture wing lengths. The first part of this paper examines the influence of fracture conductivity on the well response. In practice, the fracture conductivity is a decreasing function of distance from the wellbore. If the fracture conductivity decreases monotonically with distance from the wellbore, then at late times the variable fracture conductivity solutions behave like a constant-conductivity fracture, with conductivity equal to the arithmetic average of the conductivity. At early times the response is identical to that of a constant-conductivity fracture, corresponding to the highest conductivity of the fracture. For the variable fracture conductivity case, the bilinear flow period characterized by a one-quarter slope line may be obscured. Thus, analysis of short-time data can be difficult. The authors also consider situations where the fracture conductivity does not decrease monotonically with distance. The response for these cases is discussed in detail. The second part of the paper examines the effect of unequal wing lengths on the pressure response. The authors delineate conditions under which the effect of wing length on the response will become dominant. They discuss the influence of wing length on both early- and long-time data.

  5. Fracture theory based on the concept of characteristic fracture length of materials

    Institute of Scientific and Technical Information of China (English)

    MUTOH; Yoshiharu

    2009-01-01

    Fracture theory is a classic,but not a well-dealt with,difficulty in solid mechanics. This paper has proposed the concept of characteristic fracture length of materials from the fact that fracture happens with area failure rather than point failure in materials. A unified theory is then proposed,which can be applied both to smooth and defected materials (whether with micro or macro defects). Brittle fracture tests with specimens of different sizes of holes are carried out to examine the fracture theory. It is found that the fracture stresses obtained by experiments agree well with those predicated by the presented fracture theory. Though the brittle fracture is the focus of the paper,the concept of characteristic length can be easily extended to fatigue or other failure problems.

  6. Response of wells producing layered reservoirs: Unequal fracture length

    Energy Technology Data Exchange (ETDEWEB)

    Camacho, R.G.; Raghavan, R.; Reynolds, A.C.

    1987-03-01

    The response of fractured wells producing noncommunicating layered reservoirs is the focus of this work. The conductivity of the fracture is assumed to be finite. The fracture length is assumed to vary from layer to layer. Two modes of production - constant wellbore pressure and constant rate - are considered. In the first part, the fractures are assumed to communicate only at the wellbore. The results given in this section are intended to provide engineers with analytical capabilities to examine responses in wells where the layers that have been stimulated are separated by considerable distances. Procedures to interpret the results of pressure buildup and/or production tests (drawdown responses) in terms of layer properties are presented. Criteria to ensure maximum productivity are specified. The second part examines well responses when the fractures are in communication at points other than the wellbore. All other things being identical, we show that communication between fractures increases productivity.

  7. Response of wells producing layered reservoirs: Unequal fracture length

    Energy Technology Data Exchange (ETDEWEB)

    Camacho-V., R.G.; Raghavan, R.; Reynolds, A.C.

    1984-05-01

    The response of fractured wells producing noncommunicating layered reservoirs is the focus of this work. The conductivity of the fracture is assumed to be finite. The fracture length is assumed to vary from layer to layer. Two modes of production--constant wellbore pressure and constant rate--are considered. In the first part of this work the fractures are assumed to communicate only at the wellbore. The results given in this section are intended to provide engineers with analytical capabilities to examine responses in wells where the layers that have been stimulated are separated by considerable distances. Procedures to interpret the results of pressure buildup and/or production tests (drawdown responses) in terms of layer properties are presented. Criteria to ensure maximum productivity are specified. The second part of this work examines well responses when the fractures are in communication at points other than the wellbore. All other things being identical, the authors show that communication between fractures increases productivity.

  8. Influence of fracture heterogeneity and wing length on the response of vertically fractured wells

    Energy Technology Data Exchange (ETDEWEB)

    Bennett, C.O.; Raghavan, R.; Reynolds, A.C.; Rosato, N.D.

    1983-04-01

    A finite-conductivity vertical fracture intersecting a well produced at a constant rate or at a constant pressure is considered. The pressure (or rate) response is obtained from a numerical model. Two aspects of this problem are considered: variable fracture conductivity and unequal fracture wing lengths. The first part of this paper examines the influence of fracture conductivity on the well response. In practice, the fracture conductivity is a decreasing function of distance from the wellbore. If the fracture conductivity decreases monotonically with distance from the wellbore, then at late times the variable fracture conductivity solutions behave like a constant-conductivity fracture, with conductivity equal to the arithmetic average of the conductivity. At early times the response is identical to that of a constant-conductivity fracture, corresponding to the highest conductivity of the fracture. For the variable fracture conductivity case, the bilinear flow period characterized by a one-quarter slope line may be obscured. Thus, analysis of short-time data can be difficult. The authors also consider situations where the fracture conductivity does not decrease monotonically with distance. The response for these cases is discussed in detail. The second part of the paper examines the effect of unequal wing lengths on the pressure response.

  9. Monitoring hydraulic fracturing with seismic emission volume

    Science.gov (United States)

    Niu, F.; Tang, Y.; Chen, H.; TAO, K.; Levander, A.

    2014-12-01

    Recent developments in horizontal drilling and hydraulic fracturing have made it possible to access the reservoirs that are not available for massive production in the past. Hydraulic fracturing is designed to enhance rock permeability and reservoir drainage through the creation of fracture networks. Microseismic monitoring has been proven to be an effective and valuable technology to image hydraulic fracture geometry. Based on data acquisition, seismic monitoring techniques have been divided into two categories: downhole and surface monitoring. Surface monitoring is challenging because of the extremely low signal-to-noise ratio of the raw data. We applied the techniques used in earthquake seismology and developed an integrated monitoring system for mapping hydraulic fractures. The system consists of 20 to 30 state-of-the-art broadband seismographs, which are generally about hundreds times more sensible than regular geophones. We have conducted two experiments in two basins with very different geology and formation mechanism in China. In each case, we observed clear microseismic events, which may correspond to the induced seismicity directly associated with fracturing and the triggered ones at pre-existing faults. However, the magnitude of these events is generally larger than magnitude -1, approximately one to two magnitudes larger than those detected by downhole instruments. Spectrum-frequency analysis of the continuous surface recordings indicated high seismic energy associated with injection stages. The seismic energy can be back-projected to a volume that surrounds each injection stage. Imaging seismic emission volume (SEV) appears to be an effective way to map the stimulated reservior volume, as well as natural fractures.

  10. The dynamics of rapid fracture: instabilities, nonlinearities and length scales.

    Science.gov (United States)

    Bouchbinder, Eran; Goldman, Tamar; Fineberg, Jay

    2014-04-01

    The failure of materials and interfaces is mediated by cracks, almost singular dissipative structures that propagate at velocities approaching the speed of sound. Crack initiation and subsequent propagation-the dynamic process of fracture-couples a wide range of time and length scales. Crack dynamics challenge our understanding of the fundamental physics processes that take place in the extreme conditions within the almost singular region where material failure occurs. Here, we first briefly review the classic approach to dynamic fracture, namely linear elastic fracture mechanics (LEFM), and discuss its successes and limitations. We show how, on the one hand, recent experiments performed on straight cracks propagating in soft brittle materials have quantitatively confirmed the predictions of this theory to an unprecedented degree. On the other hand, these experiments show how LEFM breaks down as the singular region at the tip of a crack is approached. This breakdown naturally leads to a new theoretical framework coined 'weakly nonlinear fracture mechanics', where weak elastic nonlinearities are incorporated. The stronger singularity predicted by this theory gives rise to a new and intrinsic length scale, ℓnl. These predictions are verified in detail through direct measurements. We then theoretically and experimentally review how the emergence of ℓnl is linked to a new equation for crack motion, which predicts the existence of a high-speed oscillatory crack instability whose wavelength is determined by ℓnl. We conclude by delineating outstanding challenges in the field.

  11. Productivity Analysis of Volume Fractured Vertical Well Model in Tight Oil Reservoirs

    Directory of Open Access Journals (Sweden)

    Jiahang Wang

    2017-01-01

    Full Text Available This paper presents a semianalytical model to simulate the productivity of a volume fractured vertical well in tight oil reservoirs. In the proposed model, the reservoir is a composite system which contains two regions. The inner region is described as formation with finite conductivity hydraulic fracture network and the flow in fracture is assumed to be linear, while the outer region is simulated by the classical Warren-Root model where radial flow is applied. The transient rate is calculated, and flow patterns and characteristic flowing periods caused by volume fractured vertical well are analyzed. Combining the calculated results with actual production data at the decline stage shows a good fitting performance. Finally, the effects of some sensitive parameters on the type curves are also analyzed extensively. The results demonstrate that the effect of fracture length is more obvious than that of fracture conductivity on improving production in tight oil reservoirs. When the length and conductivity of main fracture are constant, the contribution of stimulated reservoir volume (SRV to the cumulative oil production is not obvious. When the SRV is constant, the length of fracture should also be increased so as to improve the fracture penetration and well production.

  12. Fracture behaviour of finite length flaws in pressure tubes

    Energy Technology Data Exchange (ETDEWEB)

    Metzger, D.R. [Atomic Energy of Canada Limited, Mississauga, Ontario (Canada); Shek, G.; Ho, E. [Kinectrics, Inc., Toronto, Ontario (Canada)

    2006-07-01

    Flaws encountered in nuclear pressure tubes must be evaluated to ensure that a hydride induced cracking mechanism, called delayed hydride cracking (DHC), is not initiated. The stress concentration at a flaw tip causes diffusion of hydrogen and precipitation of zirconium hydride at the flaw tip. Typically, assessment is done based on experimental data obtained from two-dimensional flaws. However, realistic lengths of flaws make the two-dimensional approach overly conservative in many cases, and costly remedial action may be prescribed unnecessarily. A fracture initiation model for DHC involves a type of process zone description to account for the interaction of hydride precipitation with the flaw tip stress distribution. Analytical techniques for this model based on weight functions are practical and accurate for two-dimensional geometry, but cannot be easily applied to the three-dimensional features of finite length flaws. Recently, a numerical rendition of the model has been incorporated into a finite element program so that arbitrary geometry and material properties can be managed. The process zone is automatically generated as hydride formation progresses, and a displacement parameter derived from the finite element distributions quantifies the response relative to an experimentally established fracture initiation threshold. The three-dimensional finite length model is applied to specific flaw geometries used in an experimental program. Comparison with corresponding two-dimensional tests demonstrates that the finite length flaw has a significantly higher threshold load than that predicted on the basis of a two-dimensional model. (author)

  13. Mechanical Behaviour of Materials Volume II Fracture Mechanics and Damage

    CERN Document Server

    François, Dominique; Zaoui, André

    2013-01-01

    Designing new structural materials, extending lifetimes and guarding against fracture in service are among the preoccupations of engineers, and to deal with these they need to have command of the mechanics of material behaviour. This ought to reflect in the training of students. In this respect, the first volume of this work deals with elastic, elastoplastic, elastoviscoplastic and viscoelastic behaviours; this second volume continues with fracture mechanics and damage, and with contact mechanics, friction and wear. As in Volume I, the treatment links the active mechanisms on the microscopic scale and the laws of macroscopic behaviour. Chapter I is an introduction to the various damage phenomena. Chapter II gives the essential of fracture mechanics. Chapter III is devoted to brittle fracture, chapter IV to ductile fracture and chapter V to the brittle-ductile transition. Chapter VI is a survey of fatigue damage. Chapter VII is devoted to hydogen embrittlement and to environment assisted cracking, chapter VIII...

  14. A comparison of locked versus nonlocked Enders rods for length unstable pediatric femoral shaft fractures.

    Science.gov (United States)

    Ellis, Henry Bone; Ho, Christine A; Podeszwa, David A; Wilson, Philip L

    2011-12-01

    Stainless steel flexible Enders rods have been used for intramedullary fixation of pediatric femur fractures with good success. Despite intraoperative anatomic alignment, length unstable femur fractures can present postoperatively with fracture shortening. The purpose of this study was to review all length unstable pediatric femoral shaft fractures in which Enders rods were used and compare those that were locked to those that were not locked. A retrospective clinical and radiographic review of all patients at a single institution undergoing flexible intramedullary fixation for length unstable femoral shaft fractures from 2001 to 2008. A length unstable fracture was defined as either a comminuted fracture or a spiral fracture longer than twice the diameter of the femoral shaft. A total of 107 length unstable femoral shaft fractures fixed with Enders rods were identified, of which 37 cases (35%) had both Enders rods "locked" through the eyelet in the distal femur with a 2.7 mm fully threaded cortical screw. Patient demographics, clinical course, complications, fracture characteristics, and radiographic outcomes were compared for the locked and nonlocked groups. There were no statistical differences between the groups in demographic data, operative variables, fracture pattern, fracture location, time to union, femoral alignment, or major complications. Shortening of the femur and nail migration measured at 1 to 6 weeks postoperatively was significantly greater for the nonlocked cases. The medial and lateral locked Enders rods moved 1.3 and 1.9 mm, respectively, and the unlocked Enders each moved 12.1 mm (P Enders rods for length unstable pediatric fractures is an excellent option to prevent shortening and resulted in no additional complications, added surgical time, or increased blood loss. Level III.

  15. Arc Length Based Grid Distribution For Surface and Volume Grids

    Science.gov (United States)

    Mastin, C. Wayne

    1996-01-01

    Techniques are presented for distributing grid points on parametric surfaces and in volumes according to a specified distribution of arc length. Interpolation techniques are introduced which permit a given distribution of grid points on the edges of a three-dimensional grid block to be propagated through the surface and volume grids. Examples demonstrate how these methods can be used to improve the quality of grids generated by transfinite interpolation.

  16. Arc length based grid distribution for surface and volume grids

    Energy Technology Data Exchange (ETDEWEB)

    Mastin, C.W. [NASA Langley Research Center, Hampton, VA (United States)

    1996-12-31

    Techniques are presented for distributing grid points on parametric surfaces and in volumes according to a specified distribution of arc length. Interpolation techniques are introduced which permit a given distribution of grid points on the edges of a three-dimensional grid block to be propagated through the surface and volume grids. Examples demonstrate how these methods can be used to improve the quality of grids generated by transfinite interpolation.

  17. On the damage and fracture of nuclear graphite at multiple length-scales

    Science.gov (United States)

    Liu, Dong; Mingard, Ken; Lord, Oliver T.; Flewitt, Peter

    2017-09-01

    Gilsocarbon graphite, as a neutron moderator and load-bearing component in the core of the UK fleet of Advanced Gas-Cooled Reactors, possesses complex microstructural features including defects/pores over a range of length-scales from nanometres to millimetres in size. As a consequence, this material exhibits different characteristics when specimens of different length-scale are deformed. In this work, the deformation and fracture of this material have been characterised using in situ methods for specimens of micrometre size (meso-scale) and the results are then compared with those measured one length-scale smaller, and those at the macro-scale. At the micro-scale, sampling a volume of material (2 × 2 × 10 μm) excludes micro- and macro-size pores, the strength was measured to be as high as 1000 MPa (an elastic modulus of about 67 GPa). When the specimen size is increased by one order of magnitude to the meso-scale, the strength is reduced to about 100 MPa (an elastic modulus of about 20 GPa) due to the inclusion of micro-size pores. For larger engineering-size specimens that include millimetre-size pores, the strength of the material averages about 20 MPa (an elastic modulus of about 11 GPa). This trend in the data is discussed and considered in the context of selecting the appropriate data for relevant multi-scale modelling.

  18. Fracture in Stabilized Soils. Volume 1.

    Science.gov (United States)

    1985-12-31

    relationships in pure cement pastes during drying (After Mindess and Young [67]). 166 57 Creep curves at different relative humidities ......... . 168 58... Mindess [68] has accomplished a comprehensive and detailed review of the application of fracture mechanics to cement and concrete. He reported from the...work of Mindess and Wittmann, it is evident that the movement of water and the size and distribution of pores or cracks were the most important

  19. Probabilistic size effect law for mode II fracture of critical lengths in snow slab weak layers

    Science.gov (United States)

    McClung, David

    2016-04-01

    Snow slab avalanches initiate by mode II fracture within relatively thin weak layers under stronger, cohesive slabs. For risk based avalanche prediction, it is important to understand the fracture properties of alpine snow. Alpine snow is a quasi-brittle material with a size effect on nominal shear strength meaning that strength decreases with increasing sample size. A related size effect is the critical length required for rapid propagation of a shear fracture. In that case, the probability of fracture increases with increasing crack length. In this paper, 45 sets of field measured critical lengths are presented based on 591 individual tests. From analysis, a probabilistic size effect law is derived analogous to the deterministic size effect law for nominal shear strength related to fracture mechanics. It is shown that in the limit of small crack length, the plastic limit is approached with a very low probability of failure implying very high shear strength. At the other limit, for long enough cracks, the limit of Linear Elastic Fracture Mechanics (LEFM) is approached implying high probability of failure and low nominal shear strength compatible with large sample size. It is shown that the strength size effect law and the critical length size effect law form a duality for analysis of snow avalanche weak layers. It is expected the critical length size effect law will be important in applications.

  20. Bernstein copula approach to model direction-length dependency for 2D discrete fracture network simulation

    Science.gov (United States)

    Mendoza-Torres, F.; Diaz-Viera, M. A.

    2015-12-01

    In many natural fractured porous media, such as aquifers, soils, oil and geothermal reservoirs, fractures play a crucial role in their flow and transport properties. An approach that has recently gained popularity for modeling fracture systems is the Discrete Fracture Network (DFN) model. This approach consists in applying a stochastic boolean simulation method, also known as object simulation method, where fractures are represented as simplified geometric objects (line segments in 2D and polygons in 3D). One of the shortcomings of this approach is that it usually does not consider the dependency relationships that may exist between the geometric properties of fractures (direction, length, aperture, etc), that is, each property is simulated independently. In this work a method for modeling such dependencies by copula theory is introduced. In particular, a nonparametric model using Bernstein copulas for direction-length fracture dependency in 2D is presented. The application of this method is illustrated in a case study for a fractured rock sample from a carbonate reservoir outcrop.

  1. Early intravenous ibuprofen decreases narcotic requirement and length of stay after traumatic rib fracture.

    Science.gov (United States)

    Bayouth, Lilly; Safcsak, Karen; Cheatham, Michael L; Smith, Chadwick P; Birrer, Kara L; Promes, John T

    2013-11-01

    Pain control after traumatic rib fracture is essential to avoid respiratory complications and prolonged hospitalization. Narcotics are commonly used, but adjunctive medications such as nonsteroidal anti-inflammatory drugs may be beneficial. Twenty-one patients with traumatic rib fractures treated with both narcotics and intravenous ibuprofen (IVIb) (Treatment) were retrospectively compared with 21 age- and rib fracture-matched patients who received narcotics alone (Control). Pain medication requirements over the first 7 hospital days were evaluated. Mean daily IVIb dose was 2070 ± 880 mg. Daily intravenous morphine-equivalent requirement was 19 ± 16 vs 32 ± 24 mg (P pain scores were lower in the Treatment group (P rib fractures significantly decreases narcotic requirement and results in clinically significant decreases in hospital length of stay. IVIb therapy should be initiated in patients with traumatic rib fractures to improve patient comfort and reduce narcotic requirement.

  2. Fracture Testing at Small-Length Scales: From Plasticity in Si to Brittleness in Pt

    Science.gov (United States)

    Jaya, B. Nagamani; Jayaram, Vikram

    2016-01-01

    The field of micro-/nano-mechanics of materials has been driven, on the one hand by the development of ever smaller structures in devices, and, on the other, by the need to map property variations in large systems that are microstructurally graded. Observations of `smaller is stronger' have also brought in questions of accompanying fracture property changes in the materials. In the wake of scattered articles on micro-scale fracture testing of various material classes, this review attempts to provide a holistic picture of the current state of the art. In the process, various reliable micro-scale geometries are shown, challenges with respect to instrumentation to probe ever smaller length scales are discussed and examples from recent literature are put together to exhibit the expanse of unusual fracture response of materials, from ductility in Si to brittleness in Pt. Outstanding issues related to fracture mechanics of small structures are critically examined for plausible solutions.

  3. Human lung volume, alveolar surface area, and capillary length

    DEFF Research Database (Denmark)

    Wiebe, B. M.; Laursen, Henning

    1995-01-01

    Cavalieri's principle, length density, morphometry, stereology, surface density, vertical sections, vertical slices......Cavalieri's principle, length density, morphometry, stereology, surface density, vertical sections, vertical slices...

  4. Theoretical Analysis of the Mechanism of Fracture Network Propagation with Stimulated Reservoir Volume (SRV Fracturing in Tight Oil Reservoirs.

    Directory of Open Access Journals (Sweden)

    Yuliang Su

    Full Text Available Stimulated reservoir volume (SRV fracturing in tight oil reservoirs often induces complex fracture-network growth, which has a fundamentally different formation mechanism from traditional planar bi-winged fracturing. To reveal the mechanism of fracture network propagation, this paper employs a modified displacement discontinuity method (DDM, mechanical mechanism analysis and initiation and propagation criteria for the theoretical model of fracture network propagation and its derivation. A reasonable solution of the theoretical model for a tight oil reservoir is obtained and verified by a numerical discrete method. Through theoretical calculation and computer programming, the variation rules of formation stress fields, hydraulic fracture propagation patterns (FPP and branch fracture propagation angles and pressures are analyzed. The results show that during the process of fracture propagation, the initial orientation of the principal stress deflects, and the stress fields at the fracture tips change dramatically in the region surrounding the fracture. Whether the ideal fracture network can be produced depends on the geological conditions and on the engineering treatments. This study has both theoretical significance and practical application value by contributing to a better understanding of fracture network propagation mechanisms in unconventional oil/gas reservoirs and to the improvement of the science and design efficiency of reservoir fracturing.

  5. Theoretical Analysis of the Mechanism of Fracture Network Propagation with Stimulated Reservoir Volume (SRV) Fracturing in Tight Oil Reservoirs.

    Science.gov (United States)

    Su, Yuliang; Ren, Long; Meng, Fankun; Xu, Chen; Wang, Wendong

    2015-01-01

    Stimulated reservoir volume (SRV) fracturing in tight oil reservoirs often induces complex fracture-network growth, which has a fundamentally different formation mechanism from traditional planar bi-winged fracturing. To reveal the mechanism of fracture network propagation, this paper employs a modified displacement discontinuity method (DDM), mechanical mechanism analysis and initiation and propagation criteria for the theoretical model of fracture network propagation and its derivation. A reasonable solution of the theoretical model for a tight oil reservoir is obtained and verified by a numerical discrete method. Through theoretical calculation and computer programming, the variation rules of formation stress fields, hydraulic fracture propagation patterns (FPP) and branch fracture propagation angles and pressures are analyzed. The results show that during the process of fracture propagation, the initial orientation of the principal stress deflects, and the stress fields at the fracture tips change dramatically in the region surrounding the fracture. Whether the ideal fracture network can be produced depends on the geological conditions and on the engineering treatments. This study has both theoretical significance and practical application value by contributing to a better understanding of fracture network propagation mechanisms in unconventional oil/gas reservoirs and to the improvement of the science and design efficiency of reservoir fracturing.

  6. Physical therapy services utilization and length of stay for obese patients following traumatic leg fracture.

    Science.gov (United States)

    Slayton, Stephanie; Williams, D S Blaise; Newman, Glen

    2012-01-01

    Obesity is an increasing epidemic that can complicate the treatment of simple injuries and can increase health care costs. The purpose of the present study was to determine whether obesity is a factor in the utilization of inpatient physical therapy services and length of stay following a traumatic lower leg fracture. A retrospective study of patients admitted to the hospital in 2005 and 2006 with a primary discharge diagnosis of lower leg or ankle fracture was conducted. Inclusion criteria were age > or = 18 years, only 1 involved lower extremity, and nonweight-bearing on the affected extremity per physician orders. Patients were excluded from the study if they had a fibular fracture only, pathological fractures, multiple trauma, severe cardiac or vascular comorbidities, or cognitive impairments. Data were compiled into 3 categories on the basis of body mass index (BMI): 35. Physical therapy services were measured in 15-minute units of time. These data were analyzed by within-group and between-group comparisons and with regression analysis. A total of 181 patients with a primary discharge diagnosis of distal lower extremity or ankle fracture were included in the study. Patients with a BMI >35 used more physical therapy services (mean services, 9.8 units) than did patients with a BMI of 30-35 (mean services, 6.2 units) or a BMI 35. Factors other than BMI may be associated with length of stay and physical therapy use and may confound the association. Previous studies have shown that there is an increase in health care utilization among the bariatric population. The present study demonstrates similar findings for physical therapy services. Increased length of stay and physical therapy utilization among the bariatric population also result in increased staff utilization and equipment costs.

  7. Multiphase control volume finite element simulations of fractured reservoirs

    Science.gov (United States)

    Fu, Yao

    With rapid evolution of hardware and software techniques in energy sector, reservoir simulation has become a powerful tool for field development planning and reservoir management. Many of the widely used commercial simulators were originally designed for structured grids and implemented with finite difference method (FDM). In recent years, technical advances in griding, fluid modeling, linear solver, reservoir and geological modeling, etc. have created new opportunities. At the same time, new reservoir simulation technology is required for solving large-scale heterogeneous problems. A three-dimensional, three-phase black-oil reservoir simulator has been developed using the control volume finite element (CVFE) formulation. Flux-based upstream weighting is employed to ensure flux continuity. The CVFE method is embedded in a fully-implicit formulation. State-of-the-art parallel, linear solvers are used. The implementation takes the advantages of object-oriented programming capabilities of C++ to provide maximum reuse and extensibility for future students. The results from the simulator have excellent agreement with those from commercial simulators. The convergence properties of the new simulator are verified using the method of manufactured solutions. The pressure and saturation solutions are verified to be first-order convergent as expected. The efficiency of the simulators and their capability to handle real large-scale field models are improved by implementing the models in parallel. Another aspect of the work dealt with multiphase flow of fractured reservoirs was performed. The discrete-fracture model is implemented in the simulator. Fractures and faults are represented by lines and planes in two- and three-dimensional spaces, respectively. The difficult task of generating an unstructured mesh for complex domains with fractures and faults is accomplished in this study. Applications of this model for two-phase and three-phase simulations in a variety of fractured

  8. Maximum length of large diameter Czochralski silicon single crystals at fracture stress limit of seed

    Science.gov (United States)

    Kim, K. M.; Smetana, P.

    1990-03-01

    Growth of large diameter Czochralski (CZ) silicon crystals require complete elimination of dislocations by means of Dash technique, where the seed diameter is reduced to a small size typically 3 mm in conjunction with increase in the pull rate. The maximum length of the large CZ silicon is estimated at the fracture stress limit of the seed neck diameter ( d). The maximum lengths for 200 and 300 mm CZ crystals amount to 197 and 87 cm, respectively, with d = 0.3 cm; the estimated maximum weight is 144 kg.

  9. Biomechanical comparison of osteoporotic distal radius fractures fixed by distal locking screws with different length.

    Science.gov (United States)

    Liu, Xiong; Wu, Wei-dong; Fang, Ya-feng; Zhang, Mei-chao; Huang, Wen-hua

    2014-01-01

    To evaluate the postoperative stability of osteoporotic distal radius fractures fixed with distal locking screws with different length. A comminuted extra-articular dorsally unstable distal radius fracture, treated with volar locking plate system, was created. The 18 specimens were randomized into 3 groups based on distal locked screws with different length: Group A had unicortical screws with 50% length to the dorsal cortex. Group B had unicortical screws with 75% length to the dorsal cortex. Group C had bicortical screws. Axial compression and bending loads were imposed on the models before and after cycling testing as well as load to clinical and catastrophic failure. Minimum change in stiffness was observed before and after fatigue for all groups. The final stiffness to bending forces was statistically similar in all groups, but stiffness to axial compression was statistically significant different: Group A approached significance with respect to groups B and C (P = 0.017, 0.009), whereas stiffness in group B and C was statistically similar (P = 0.93). Load to clinical failure was significantly less for group A (456.54±78.59 N) compared with groups B (580.24±73.85 N) and C (591.07±38.40 N). Load to catastrophic failure was statistically similar between groups, but mean values for Group A were 18% less than means for Group C. The volar locking plate system fixed with unicortical locking screws with at least 75% length not only produced early stability for osteoporotic distal radius fractures, but also avoided extensor tendon complications due to dorsal screw protrusion.

  10. Biomechanical comparison of osteoporotic distal radius fractures fixed by distal locking screws with different length.

    Directory of Open Access Journals (Sweden)

    Xiong Liu

    Full Text Available To evaluate the postoperative stability of osteoporotic distal radius fractures fixed with distal locking screws with different length.A comminuted extra-articular dorsally unstable distal radius fracture, treated with volar locking plate system, was created. The 18 specimens were randomized into 3 groups based on distal locked screws with different length: Group A had unicortical screws with 50% length to the dorsal cortex. Group B had unicortical screws with 75% length to the dorsal cortex. Group C had bicortical screws. Axial compression and bending loads were imposed on the models before and after cycling testing as well as load to clinical and catastrophic failure.Minimum change in stiffness was observed before and after fatigue for all groups. The final stiffness to bending forces was statistically similar in all groups, but stiffness to axial compression was statistically significant different: Group A approached significance with respect to groups B and C (P = 0.017, 0.009, whereas stiffness in group B and C was statistically similar (P = 0.93. Load to clinical failure was significantly less for group A (456.54±78.59 N compared with groups B (580.24±73.85 N and C (591.07±38.40 N. Load to catastrophic failure was statistically similar between groups, but mean values for Group A were 18% less than means for Group C.The volar locking plate system fixed with unicortical locking screws with at least 75% length not only produced early stability for osteoporotic distal radius fractures, but also avoided extensor tendon complications due to dorsal screw protrusion.

  11. Development of Compartment Syndrome Negatively Impacts Length of Stay and Cost After Tibia Fracture.

    Science.gov (United States)

    Crespo, Alexander M; Manoli, Arthur; Konda, Sanjit R; Egol, Kenneth A

    2015-07-01

    To quantify the impact of compartment syndrome in the setting of tibial shaft fracture on hospital length of stay (LOS) and total hospital charges. Retrospective case-control study. All New York State hospital admissions from 2001 to 2011, as recorded by the New York Statewide Planning and Research Cooperative System database. Thirty three thousand six hundred twenty-nine inpatients with isolated open or closed fractures of the tibia and/or fibula (AO/OTA 41-43). Six hundred ninety-two patients developed a compartment syndrome in the setting of tibia fracture. All patients were filtered to ensure none had other complications or medical comorbidities that would increase LOS or total hospital charges. Fasciotomy and delayed closure in patients who developed a compartment syndrome. Hospital LOS (days) and total inflation-adjusted hospital charges. A total of 33,629 patients with tibial shaft fracture were included in the study. There were 32,937 patients who did not develop a compartment syndrome. For this group, the mean LOS was 6 days, and the mean inflation-adjusted hospital charges were $34,000. Patients who developed compartment syndrome remained in-house for an average of 14 days with average charges totaling $79,000. These differences were highly significant for both lengths of stay and hospital charges (P compartment syndrome, there is also a significant economic impact to the healthcare system. Compartment syndrome after a tibial fracture more than doubles LOS and total hospital charges. These findings highlight the need for a standardized care algorithm aimed toward efficiently and adequately treating acute compartment syndrome. Such an algorithm would optimize cost of care and presumably decrease LOS. Economic Level IV. See Instructions for Authors for a complete description of levels of evidence.

  12. New-Onset Depression Following Hip Fracture Is Associated With Increased Length of Stay in Hospital and Rehabilitation Centers

    Directory of Open Access Journals (Sweden)

    Anna C. Phillips

    2015-05-01

    Full Text Available This article examines the coincident effects of new-onset depression post hip fracture on length of hospital stay, readmission rates, and incidence of infections in older adults. Participants were 101 hip fracture patients aged 60+ years; 38 developed depressive symptoms following their fracture. Infection rates, readmissions to hospital and rehabilitation units, and length of hospital stay were assessed over the 6 months post hip fracture from hospital and general practitioner notes. Patients who developed depression by Week 6 post fracture were likely to spend more time in hospital/rehabilitation wards (p = .02 and more likely to be discharged to a rehabilitation unit (p < .05. There were no group differences in readmissions or infection rates. New-onset depression coincident with hip fracture in older adults is associated with longer hospital ward stays and greater need for rehabilitation.

  13. PREDICTION OF CHARACTERISTIC LENGTH AND FRACTURE TOUGHNESS IN DUCTILE-BRITTLE TRANSITION

    Energy Technology Data Exchange (ETDEWEB)

    Lam, P

    2008-04-15

    Finite element method was used to analyze the three-point bend experimental data of A533B-1 pressure vessel steel obtained by Sherry, Lidbury, and Beardsmore [1] from -160 to -45 C within the ductile-brittle transition regime. As many researchers have shown, the failure stress ({sigma}{sub f}) of the material could be approximated as a constant. The characteristic length, or the critical distance (r{sub c}) from the crack tip, at which {sigma}{sub f} is reached, is shown to be temperature dependent based on the crack tip stress field calculated by the finite element method. With the J-A{sub 2} two-parameter constraint theory in fracture mechanics, the fracture toughness (J{sub C} or K{sub JC}) can be expressed as a function of the constraint level (A{sub 2}) and the critical distance r{sub c}. This relationship is used to predict the fracture toughness of A533B-1 in the ductile-brittle transition regime with a constant {sigma}{sub f} and a set of temperature-dependent r{sub c}. It can be shown that the prediction agrees well with the test data for wide range of constraint levels from shallow cracks (a/W= 0.075) to deep cracks (a/W= 0.5), where a is the crack length and W is the specimen width.

  14. Length of preoperative hospital stay: a risk factor for reducing surgical infection in femoral fracture cases

    Directory of Open Access Journals (Sweden)

    Hoberdan Oliveira Pereira

    2015-12-01

    Full Text Available ABSTRACT OBJECTIVE: To analyze infections of the surgical site among patients undergoing clean-wound surgery for correction of femoral fractures. METHODS: This was a historical cohort study developed in a large-sized hospital in Belo Horizonte. Data covering the period from July 2007 to July 2009 were gathered from the records in electronic medical files, relating to the characteristics of the patients, surgical procedures and surgical infections. The risk factors for infection were identified by means of statistical tests on bilateral hypotheses, taking the significance level to be 5%. Continuous variables were evaluated using Student'sttest. Categorical variables were evaluated using the chi-square test, or Fisher's exact test, when necessary. For each factor under analysis, a point estimate and the 95% confidence interval for the relative risk were obtained. In the final stage of the study, multivariate logistic regression analysis was performed. RESULTS: 432 patients who underwent clean-wound surgery for correcting femoral fractures were included in this study. The rate of incidence of surgical site infections was 4.9% and the risk factors identified were the presence of stroke (odds ratio, OR = 5.0 and length of preoperative hospital stay greater than four days (OR = 3.3. CONCLUSION: To prevent surgical site infections in operations for treating femoral fractures, measures involving assessment of patients' clinical conditions by a multiprofessional team, reduction of the length of preoperative hospital stay and prevention of complications resulting from infections will be necessary.

  15. A Study of Number Conservation With Tasks Which Vary in Length, Area and Volume. Final Report.

    Science.gov (United States)

    Taranto, Maria; Mermelstein, Egon

    The objective of this study was an attempt to clarify the nature of number conservation with number conservation tasks using variations in length, area, and volume. According to Piagetian theory, conservation is attained successively for number, length, area, and, finally, volume. It was hypothesized that success on the number conservation tasks…

  16. Critical length sampling: a method to estimate the volume of downed coarse woody debris

    Science.gov (United States)

    G& #246; ran St& #229; hl; Jeffrey H. Gove; Michael S. Williams; Mark J. Ducey

    2010-01-01

    In this paper, critical length sampling for estimating the volume of downed coarse woody debris is presented. Using this method, the volume of downed wood in a stand can be estimated by summing the critical lengths of down logs included in a sample obtained using a relascope or wedge prism; typically, the instrument should be tilted 90° from its usual...

  17. Peripheral telomere length and hippocampal volume in adolescents with major depressive disorder.

    Science.gov (United States)

    Henje Blom, E; Han, L K M; Connolly, C G; Ho, T C; Lin, J; LeWinn, K Z; Simmons, A N; Sacchet, M D; Mobayed, N; Luna, M E; Paulus, M; Epel, E S; Blackburn, E H; Wolkowitz, O M; Yang, T T

    2015-11-10

    Several studies have reported that adults with major depressive disorder have shorter telomere length and reduced hippocampal volumes. Moreover, studies of adult populations without major depressive disorder suggest a relationship between peripheral telomere length and hippocampal volume. However, the relationship of these findings in adolescents with major depressive disorder has yet to be explored. We examined whether adolescent major depressive disorder is associated with altered peripheral telomere length and hippocampal volume, and whether these measures relate to one another. In 54 unmedicated adolescents (13-18 years) with major depressive disorder and 63 well-matched healthy controls, telomere length was assessed from saliva using quantitative polymerase chain reaction methods, and bilateral hippocampal volumes were measured with magnetic resonance imaging. After adjusting for age and sex (and total brain volume in the hippocampal analysis), adolescents with major depressive disorder exhibited significantly shorter telomere length and significantly smaller right, but not left hippocampal volume. When corrected for age, sex, diagnostic group and total brain volume, telomere length was not significantly associated with left or right hippocampal volume, suggesting that these cellular and neural processes may be mechanistically distinct during adolescence. Our findings suggest that shortening of telomere length and reduction of hippocampal volume are already present in early-onset major depressive disorder and thus unlikely to be only a result of accumulated years of exposure to major depressive disorder.

  18. Length-scale and strain rate-dependent mechanism of defect formation and fracture in carbon nanotubes under tensile loading

    Science.gov (United States)

    Javvaji, Brahmanandam; Raha, S.; Mahapatra, D. Roy

    2017-02-01

    Electromagnetic and thermo-mechanical forces play a major role in nanotube-based materials and devices. Under high-energy electron transport or high current densities, carbon nanotubes fail via sequential fracture. The failure sequence is governed by certain length scale and flow of current. We report a unified phenomenological model derived from molecular dynamic simulation data, which successfully captures the important physics of the complex failure process. Length-scale and strain rate-dependent defect nucleation, growth, and fracture in single-walled carbon nanotubes with diameters in the range of 0.47 to 2.03 nm and length which is about 6.17 to 26.45 nm are simulated. Nanotubes with long length and small diameter show brittle fracture, while those with short length and large diameter show transition from ductile to brittle fracture. In short nanotubes with small diameters, we observe several structural transitions like Stone-Wales defect initiation, its propagation to larger void nucleation, formation of multiple chains of atoms, conversion to monatomic chain of atoms, and finally complete fracture of the carbon nanotube. Hybridization state of carbon-carbon bonds near the end cap evolves, leading to the formation of monatomic chain in short nanotubes with small diameter. Transition from ductile to brittle fracture is also observed when strain rate exceeds a critical value. A generalized analytical model of failure is established, which correlates the defect energy during the formation of atomic chain with aspect ratio of the nanotube and strain rate. Variation in the mechanical properties such as elastic modulus, tensile strength, and fracture strain with the size and strain rate shows important implications in mitigating force fields and ways to enhance the life of electronic devices and nanomaterial conversion via fracture in manufacturing.

  19. Hip axis length is a FRAX- and bone density-independent risk factor for hip fracture in women.

    Science.gov (United States)

    Leslie, William D; Lix, Lisa M; Morin, Suzanne N; Johansson, Helena; Odén, Anders; McCloskey, Eugene V; Kanis, John A

    2015-05-01

    Bone mineral density (BMD) measurement from dual-energy X-ray absorptiometry (DXA) is widely used to assess skeletal strength in clinical practice, but DXA instruments can also measure biomechanical parameters related to skeletal shape. The objective of the study was to determine whether DXA-derived hip geometry measures provide information on fracture prediction that is independent of hip fracture probability determined from the fracture risk assessment tool (FRAX) algorithm. This was a retrospective registry study using BMD results for Manitoba, Canada. Women aged 40 years and older with baseline hip DXA, derived hip geometry measures, and FRAX scores (n = 50 420) participated in the study. Hospitalized hip fracture (n = 1020) diagnosed during 319 137 person-years of follow-up (median 6.4 y) was measured. Among the hip geometry measures, hip axis length (HAL) showed a consistent association with hip fracture risk when adjusted for age [hazard ratio (HR) 1.30 per SD increase, 95% confidence interval (CI) 1.22-1.38], and this was unaffected by further adjustment for BMD or FRAX score. Adjusted for FRAX score with BMD, there was a significant effect of increasing HAL quintile on hip fracture risk (linear trend P hip geometry measurements are associated with incident hip fracture risk, but many do not confer significant independent predictive information. HAL was found to predict hip fractures when adjusted for BMD or FRAX score and may be of clinical value in refining hip fracture risk.

  20. Effect of length post and remaining root tissue on fracture resistance of fibre posts relined with resin composite.

    Science.gov (United States)

    Farina, A P; Weber, A L; Severo, B de P; Souza, M A; Cecchin, D

    2015-03-01

    To investigate the influence of post length and amount of remaining root tissue on the fracture resistance of roots restored with fibre posts relined with resin composite. Ninety upper canine teeth were divided into nine groups (n = 10). The post spaces were prepared resulting in different lengths, as follows: group 2/3, preparations with lengths of 10 mm; group 1/2, preparations with lengths of 7·5 mm; and group 1/3, preparations with lengths of 5 mm. Each group was divided into 3 subgroups according to amount of remaining root tooth tissue (2, 1 mm or 0·5 mm of thick root). Fibre posts relined with resin composite were cemented, and all teeth were restored with metal crowns. The samples were submitted to the fracture resistance test in a universal testing machine, at an angle of 135° and speed of 0·5 mm min(-1) . Failure modes were observed and the data of fracture resistance were submitted to the anova and Tukey's (α = 0·05). No statistically significant difference in fracture resistance was found among different post lengths (P > 0·05). Remaining dentin thickness of 2 and 1 mm did not differ statistically in fracture resistance (P > 0·05), which was higher than of 0·5 mm dentin thickness (P resin composite did not influence fracture resistance, but thickness was an important factor for the restoration of endodontically treated teeth.

  1. The effects of axial length on the fracture and fragmentation of expanding rings

    Directory of Open Access Journals (Sweden)

    Razorenov S.V.

    2012-08-01

    Full Text Available Rings of Ti-6Al-4V with aspect ratios (wall thickness:axial length of 1 : 1, 1 : 2 and 1 : 4 have been expanded to failure at radial strain rates εr ∼ 1 × 104 s−1 using 4340 (EN24T steel and Cu-ETP cylindrical drivers containing a column of RDX. Expansion velocity was measured using VISAR enabling calculation of the stress-strain history of the ring alongside fragment recovery with up to 98% original ring mass recovered. Using the recovered samples average fragment length and mass and final strain have been measured along with analysis of the fracture sites to determine the active failure mechanisms. Perfect rings (aspect ratio 1 : 1 were found to undergo necking before failure, whereas the longer rings failed though ductile tensile cracking at 45∘ to the radius. This data is then compared with finite element analysis results.

  2. he relationship of body mass index to penile length and testicular volume in adolescent boys

    Directory of Open Access Journals (Sweden)

    Rizky Adriansyah

    2012-09-01

    Full Text Available Background Evidence suggests that obesity may be related to early onset of puberty in girls. However, few studies have found a link between body mass index (BMI and puberty onset in boys. More study is needed to assess the relationship of BMI to penile length and testicular volume. Objective To investigate the relationship of BMI to penile length and testicular volume in adolescent boys. Methods A cross-sectional study was carried out on adolescent boys aged 9 to 14 years in Secanggang District, Langkat Regency, North Sumatera Province in August 2009. Subject's BMIs were calculated by dividing body weight (BW in kilograms by body height (BH in meters squared. Penile length (cm was measured with a spatula. We took the average of three measurements from the symphysis pubis to the tip of the glans penis. Testicular volume (mL was estimated by palpation using an orchidometer. Pearson's correlation test (r was used to assess the relationship of BMI to penile length and BMI to testicular volume. Results There were 108 participants, consisting of 64 primary school students and 44 junior high school students. Subjects' mean age was 11.7 (SD 1.62 years,; mean BW was 35.2 (SD 8.84 kg; mean testicular volume was 3.6 (SD 1.20 mL. We found no significant association between BMI and penile length (r=-0.25, P= 0.006, nor between BMI and testicular volume (r=-021; P=0.09. Conclusion There was no significant relationship of BMI to penile length nor BMI to testicular volume in adolescent boys. [

  3. An element-based finite-volume method approach for naturally fractured compositional reservoir simulation

    Energy Technology Data Exchange (ETDEWEB)

    Marcondes, Francisco [Federal University of Ceara, Fortaleza (Brazil). Dept. of Metallurgical Engineering and Material Science], e-mail: marcondes@ufc.br; Varavei, Abdoljalil; Sepehrnoori, Kamy [The University of Texas at Austin (United States). Petroleum and Geosystems Engineering Dept.], e-mails: varavei@mail.utexas.edu, kamys@mail.utexas.edu

    2010-07-01

    An element-based finite-volume approach in conjunction with unstructured grids for naturally fractured compositional reservoir simulation is presented. In this approach, both the discrete fracture and the matrix mass balances are taken into account without any additional models to couple the matrix and discrete fractures. The mesh, for two dimensional domains, can be built of triangles, quadrilaterals, or a mix of these elements. However, due to the available mesh generator to handle both matrix and discrete fractures, only results using triangular elements will be presented. The discrete fractures are located along the edges of each element. To obtain the approximated matrix equation, each element is divided into three sub-elements and then the mass balance equations for each component are integrated along each interface of the sub-elements. The finite-volume conservation equations are assembled from the contribution of all the elements that share a vertex, creating a cell vertex approach. The discrete fracture equations are discretized only along the edges of each element and then summed up with the matrix equations in order to obtain a conservative equation for both matrix and discrete fractures. In order to mimic real field simulations, the capillary pressure is included in both matrix and discrete fracture media. In the implemented model, the saturation field in the matrix and discrete fractures can be different, but the potential of each phase in the matrix and discrete fracture interface needs to be the same. The results for several naturally fractured reservoirs are presented to demonstrate the applicability of the method. (author)

  4. Leukocyte telomere length and hippocampus volume: a meta-analysis [version 1; referees: 2 approved

    Directory of Open Access Journals (Sweden)

    Gustav Nilsonne

    2015-10-01

    Full Text Available Leukocyte telomere length has been shown to correlate to hippocampus volume, but effect estimates differ in magnitude and are not uniformly positive. This study aimed primarily to investigate the relationship between leukocyte telomere length and hippocampus gray matter volume by meta-analysis and secondarily to investigate possible effect moderators. Five studies were included with a total of 2107 participants, of which 1960 were contributed by one single influential study. A random-effects meta-analysis estimated the effect to r = 0.12 [95% CI -0.13, 0.37] in the presence of heterogeneity and a subjectively estimated moderate to high risk of bias. There was no evidence that apolipoprotein E (APOE genotype was an effect moderator, nor that the ratio of leukocyte telomerase activity to telomere length was a better predictor than leukocyte telomere length for hippocampus volume. This meta-analysis, while not proving a positive relationship, also is not able to disprove the earlier finding of a positive correlation in the one large study included in analyses. We propose that a relationship between leukocyte telomere length and hippocamus volume may be mediated by transmigrating monocytes which differentiate into microglia in the brain parenchyma.

  5. Development of Fracture Mechanics Maps for Composite Materials. Volume 4.

    Science.gov (United States)

    1985-12-01

    Garber. "Tensile Stress-Strain Behavior oi Graphite/Epoxy Laminates", NASA CR 3592, 1982. 42. G. Caprino , J.C. Halpin and L. Nicolais, "Fracture...2336. 84. C. Caprino , "On the Prediction of Residual Strength for Notched Laminate". Journal Materials Science, Vol. 18, 1983, pp. 2269-2273. 8j. D.L

  6. An ancient relation between units of length and volume based on a sphere.

    Directory of Open Access Journals (Sweden)

    Elena Zapassky

    Full Text Available The modern metric system defines units of volume based on the cube. We propose that the ancient Egyptian system of measuring capacity employed a similar concept, but used the sphere instead. When considered in ancient Egyptian units, the volume of a sphere, whose circumference is one royal cubit, equals half a hekat. Using the measurements of large sets of ancient containers as a database, the article demonstrates that this formula was characteristic of Egyptian and Egyptian-related pottery vessels but not of the ceramics of Mesopotamia, which had a different system of measuring length and volume units.

  7. LNG cascading damage study. Volume I, fracture testing report.

    Energy Technology Data Exchange (ETDEWEB)

    Petti, Jason P.; Kalan, Robert J.

    2011-12-01

    As part of the liquefied natural gas (LNG) Cascading Damage Study, a series of structural tests were conducted to investigate the thermal induced fracture of steel plate structures. The thermal stresses were achieved by applying liquid nitrogen (LN{sub 2}) onto sections of each steel plate. In addition to inducing large thermal stresses, the lowering of the steel temperature simultaneously reduced the fracture toughness. Liquid nitrogen was used as a surrogate for LNG due to safety concerns and since the temperature of LN{sub 2} is similar (-190 C) to LNG (-161 C). The use of LN{sub 2} ensured that the tests could achieve cryogenic temperatures in the range an actual vessel would encounter during a LNG spill. There were four phases to this test series. Phase I was the initial exploratory stage, which was used to develop the testing process. In the Phase II series of tests, larger plates were used and tested until fracture. The plate sizes ranged from 4 ft square pieces to 6 ft square sections with thicknesses from 1/4 inches to 3/4 inches. This phase investigated the cooling rates on larger plates and the effect of different notch geometries (stress concentrations used to initiate brittle fracture). Phase II was divided into two sections, Phase II-A and Phase II-B. Phase II-A used standard A36 steel, while Phase II-B used marine grade steels. In Phase III, the test structures were significantly larger, in the range of 12 ft by 12 ft by 3 ft high. These structures were designed with more complex geometries to include features similar to those on LNG vessels. The final test phase, Phase IV, investigated differences in the heat transfer (cooling rates) between LNG and LN{sub 2}. All of the tests conducted in this study are used in subsequent parts of the LNG Cascading Damage Study, specifically the computational analyses.

  8. Numerical evaluation of the phase-field model for brittle fracture with emphasis on the length scale

    Science.gov (United States)

    Zhang, Xue; Vignes, Chet; Sloan, Scott W.; Sheng, Daichao

    2017-05-01

    The phase-field model has been attracting considerable attention due to its capability of capturing complex crack propagations without mesh dependence. However, its validation studies have primarily focused on the ability to predict reasonable, sharply defined crack paths. Very limited works have so far been contributed to estimate its accuracy in predicting force responses, which is majorly attributed to the difficulty in the determination of the length scale. Indeed, accurate crack path simulation can be achieved by setting the length scale to be sufficiently small, whereas a very small length scale may lead to unrealistic force-displacement responses and overestimate critical structural loads. This paper aims to provide a critical numerical investigation of the accuracy of phase-field modelling of brittle fracture with special emphasis on a possible formula for the length scale estimation. Phase-field simulations of a number of classical fracture experiments for brittle fracture in concretes are performed with simulated results compared with experimental data qualitatively and quantitatively to achieve this goal. Furthermore, discussions are conducted with the aim to provide guidelines for the application of the phase-field model.

  9. The influence of lead length on the fractures associated with leading corners and sidings

    CSIR Research Space (South Africa)

    Turner, PA

    1989-02-01

    Full Text Available Stopes on three reef horizons and at various depths were examined in the vicinity of inter-panel leads. The general geometry of fractures in the vicinity of inter-panels leads is outlined. The extend of fracturing parallel to the siding between...

  10. Relationship between CAG repeat length and brain volume in premanifest and early Huntington's disease.

    Science.gov (United States)

    Henley, Susie M D; Wild, Edward J; Hobbs, Nicola Z; Scahill, Rachael I; Ridgway, Gerard R; Macmanus, David G; Barker, Roger A; Fox, Nick C; Tabrizi, Sarah J

    2009-02-01

    Huntington's disease (HD) is caused by an expanded CAG repeat on the gene encoding for the protein huntingtin. There are conflicting findings about the extent to which repeat length predicts signs of the disease or severity of disease progression in adults. This study examined the relationship between CAG repeat length and brain volume in a large cohort of pre- and post-motor onset HD gene carriers, using voxel-based morphometry (VBM), an approach which allowed us to investigate the whole brain without defining a priori regions of interest. We also used VBM to examine group differences between 20 controls, 21 premanifest, and 40 early HD subjects. In the 61 mutation-positive subjects higher CAG repeat length was significantly associated with reduced volume of the body of the caudate nucleus bilaterally, left putamen, right insula, right parahippocampal gyrus, right anterior cingulate, and right occipital lobe, after correcting for age. The group contrasts showed significant reduction in grey matter volume in the early HD group relative to controls in widespread cortical as well as subcortical areas but there was no evidence of difference between controls and premanifest subjects. Overall we have demonstrated that increased CAG repeat length is associated with atrophy in extra-striatal as well as striatal regions, which has implications for the monitoring of disease-modifying therapies in the condition.

  11. Reduced-Volume Fracture Toughness Characterization for Transparent Polymers

    Science.gov (United States)

    2015-03-21

    the coefficient of thermal expansion α, and the specific heat capacity at a constant volume Cv, respectively. The functions f1−4 are relaxation...relaxation functions are either related to volumetric quantities (bulk modulus, coefficient of thermal expansion , and specific volumetric heat capacity) or a...product of the bulk modulus and the coefficient of thermal expansion is expressed as L = Kα, and ε dev is the deviatoric part of the integrated rate

  12. Dependence of displacement-length scaling relations for fractures and deformation bands on the volumetric changes across them

    Science.gov (United States)

    Schultz, R.A.; Soliva, R.; Fossen, H.; Okubo, C.H.; Reeves, D.M.

    2008-01-01

    Displacement-length data from faults, joints, veins, igneous dikes, shear deformation bands, and compaction bands define two groups. The first group, having a power-law scaling relation with a slope of n = 1 and therefore a linear dependence of maximum displacement and discontinuity length (Dmax = ??L), comprises faults and shear (non-compactional or non-dilational) deformation bands. These shearing-mode structures, having shearing strains that predominate over volumetric strains across them, grow under conditions of constant driving stress, with the magnitude of near-tip stress on the same order as the rock's yield strength in shear. The second group, having a power-law scaling relation with a slope of n = 0.5 and therefore a dependence of maximum displacement on the square root of discontinuity length (Dmax = ??L0.5), comprises joints, veins, igneous dikes, cataclastic deformation bands, and compaction bands. These opening- and closing-mode structures grow under conditions of constant fracture toughness, implying significant amplification of near-tip stress within a zone of small-scale yielding at the discontinuity tip. Volumetric changes accommodated by grain fragmentation, and thus control of propagation by the rock's fracture toughness, are associated with scaling of predominantly dilational and compactional structures with an exponent of n = 0.5. ?? 2008 Elsevier Ltd.

  13. Performance Analysis of Fractured Wells with Stimulated Reservoir Volume in Coal Seam Reservoirs

    Directory of Open Access Journals (Sweden)

    Yu-long Zhao

    2016-01-01

    Full Text Available CoalBed Methane (CBM, as one kind of unconventional gas, is an important energy resource, attracting industry interest in research and development. Using the Langmuir adsorption isotherm, Fick’s law in the matrix and Darcy flow in cleat fractures, and treating the Stimulated Reservoir Volume (SRV induced by hydraulic fracturing as a radial composite model, the continuous linear source function with constant production is derived by the methods of the Laplace transform and Duhamel theory. Based on the linear source function, semi-analytical solutions are obtained for a fractured vertical well producing at a constant production rate or constant bottom-hole pressure. With the help of the Stehfest numerical algorithm and computer programing, the well test and rate decline type curves are obtained, and the key flow regimes of fractured CBM wells are: wellbore storage, linear flow in SRV region, diffusion flow and later pseudo-radial flow. Finally, we analyze the effect of various parameters, such as the Langmuir volume, radius and permeability in the SRV region, on the production performance. The research results concluded in this paper have significant importance in terms of the development, well test interpretations and production performance analysis of unconventional gas.

  14. Impact of surgical complications on length of stay after hip fracture surgery

    DEFF Research Database (Denmark)

    Foss, Nicolai Bang; Palm, Henrik; Krasheninnikoff, Michael;

    2006-01-01

    BACKGROUND: Rehabilitation after hip fracture may be lengthy, with bed-day consumption accounting for up to 85% of the total cost of admission to hospital. Data suggest that surgical complications requiring reoperation may lead to an excessively long in-patient stays. However, the overall impact...... of surgical complications has not been examined in detail. METHODS: All 600 consecutive patients included were admitted with primary hip fracture and received primary surgical intervention with multimodal rehabilitation. Surgical complications were audited and classified as being due to a patient fall......, infection or suboptimal surgery, stratified into either requiring reoperation or not allowing mobilisation because of instability. RESULTS: Of the 600, 116 (19.3, 95% CI 16-22%) patients underwent reoperation or immobilisation; 27.1% of bed-day consumption resulted from surgical complications. The audit...

  15. Impact of surgical complications on length of stay after hip fracture surgery

    DEFF Research Database (Denmark)

    Foss, Nicolai Bang; Palm, Henrik; Krasheninnikoff, Michael

    2006-01-01

    BACKGROUND: Rehabilitation after hip fracture may be lengthy, with bed-day consumption accounting for up to 85% of the total cost of admission to hospital. Data suggest that surgical complications requiring reoperation may lead to an excessively long in-patient stays. However, the overall impact...... showed that 64 complications (55%) were due to suboptimal surgery, 18 (16%) to infection, 6 (5%) to falls and 28 (24%) to no obvious cause. CONCLUSION: Surgical complications secondary to primary hip fracture surgery account for 27.1% of total hospital bed consumption within 6 months. Approximately, 50......, infection or suboptimal surgery, stratified into either requiring reoperation or not allowing mobilisation because of instability. RESULTS: Of the 600, 116 (19.3, 95% CI 16-22%) patients underwent reoperation or immobilisation; 27.1% of bed-day consumption resulted from surgical complications. The audit...

  16. Ethnomathematics study: uncovering units of length, area, and volume in Kampung Naga Society

    Science.gov (United States)

    Septianawati, T.; Turmudi; Puspita, E.

    2017-02-01

    During this time, mathematics is considered as something neutral and not associated with culture. It can be seen from mathematics learning in the school which adopt many of foreign mathematics learning are considered more advanced (western). In fact, Indonesia is a rich country in cultural diversity. In the cultural activities, there are mathematical ideas that were considered a important thing in the mathematics learning. A study that examines the idea or mathematical practices in a variety of cultural activities are known as ethnomathematics. In Indonesia, there are some ethnic maintain their ancestral traditions, one of them is Kampung Naga. Therefore, this study was conducted in Kampung Naga. This study aims to uncover units of length, area, and volume used by Kampung Naga society. This study used a qualitative approach and ethnography methods. In this research, data collection is done through the principles of ethnography such as observation, interviews, documentation, and field notes. The results of this study are units of length, area, and volume used by Kampung Naga society and its conversion into standard units. This research is expected to give information to the public that mathematics has a relationship with culture and become recommendation to mathematics curriculum in Indonesia.

  17. Can serpentinization induce fracturing? Fluid pathway development and the volume increase enigma

    Science.gov (United States)

    Plümper, Oliver; Jamtveit, Bjørn; Røyne, Anja

    2013-04-01

    Serpentinization of ultramafic rocks has first-order effects on global element cycles, the rheology of the oceanic lithosphere, plays a key role in plate tectonics by lubricating subduction zones and has been linked to the origin of life due to the creation of abiogenic hydrocarbons. In addition, the capability of ultramafic rocks to safely store enormous amounts of carbon dioxide through mineral reactions may provide a unique solution to fight global warming. However, all the aforementioned processes are reliant on the creation and maintenance of fluid pathways to alter an originally impermeable rock. Although the forces that move tectonic plates can produce these fluid pathways by mechanical fracturing, there is ample evidence that serpentinization reactions can 'eat' their way through a rock. This process is facilitated by solid volume changes during mineral reactions that cause expansion, fracturing the rock to generate fluid pathways. Natural observations of serpentinization/carbonation in ultramafic rocks indicate that the associated positive solid volume change alone exerts enough stress on the surrounding rock to build up a fracture network and that the influence of external tectonic forces is not necessary. Through various feedbacks these systems can either become self-sustaining, when an interconnected fracture network is formed, or self-limiting due to fluid pathway obstruction. However, extensively serpentinized outcrops suggest that although crystal growth in newly opened spaces would reduce permeability, serpentinization is not always self-limiting as porosity generation can occur concomitantly, maintaining or even increasing permeability. This is consistent with theory and demonstrates that fluids transported through fracture networks can alter vast amounts of originally impermeable rock. Nevertheless, whether serpentinization can actually generate these fracture networks is still a matter of debate and only a few scientific investigations have

  18. Radionuclide migration through fractured rock for arbitrary-length decay chain: Analytical solution and global sensitivity analysis

    Science.gov (United States)

    Shahkarami, Pirouz; Liu, Longcheng; Moreno, Luis; Neretnieks, Ivars

    2015-01-01

    This study presents an analytical approach to simulate nuclide migration through a channel in a fracture accounting for an arbitrary-length decay chain. The nuclides are retarded as they diffuse in the porous rock matrix and stagnant zones in the fracture. The Laplace transform and similarity transform techniques are applied to solve the model. The analytical solution to the nuclide concentrations at the fracture outlet is governed by nine parameters representing different mechanisms acting on nuclide transport through a fracture, including diffusion into the rock matrices, diffusion into the stagnant water zone, chain decay and hydrodynamic dispersion. Furthermore, to assess how sensitive the results are to parameter uncertainties, the Sobol method is applied in variance-based global sensitivity analyses of the model output. The Sobol indices show how uncertainty in the model output is apportioned to the uncertainty in the model input. This method takes into account both direct effects and interaction effects between input parameters. The simulation results suggest that in the case of pulse injections, ignoring the effect of a stagnant water zone can lead to significant errors in the time of first arrival and the peak value of the nuclides. Likewise, neglecting the parent and modeling its daughter as a single stable species can result in a significant overestimation of the peak value of the daughter nuclide. It is also found that as the dispersion increases, the early arrival time and the peak time of the daughter decrease while the peak value increases. More importantly, the global sensitivity analysis reveals that for time periods greater than a few thousand years, the uncertainty of the model output is more sensitive to the values of the individual parameters than to the interaction between them. Moreover, if one tries to evaluate the true values of the input parameters at the same cost and effort, the determination of priorities should follow a certain

  19. Effect of ferrule height and glass fibre post length on fracture resistance and failure mode of endodontically treated teeth.

    Science.gov (United States)

    Abdulrazzak, Shurooq S; Sulaiman, Eshamsul; Atiya, Basim K; Jamaludin, Marhazlinda

    2014-08-01

    The purpose of this study was to evaluate the combined effect of ferrule height and post length on fracture resistance and failure mode of endodontically treated teeth restored with glass fibre posts, composite resin cores and crowns. Ninety human maxillary central incisors were endodontically treated and divided into three groups (n = 30) according to the ferrule heights: 4, 2 and 0 mm, respectively. Post spaces in each group were prepared at 2/3, 1/2 and 1/3 of the root length (n = 10). The specimens were received fibre posts, composite resin core build up and cast metal crowns. After thermocycling, compressive static load was applied at an angle of 135° to the crowns. Two-way analysis of variance showed significant differences in the failure load in the ferrule height groups, no significant differences in post length groups and no significant interaction between ferrule heights and post lengths. More restorable failure modes were observed.

  20. Diagnostic value of kidney length and volume in sonography for determining kidney scar among infants with urinary infection

    Directory of Open Access Journals (Sweden)

    Mahmoud Jalili

    2011-11-01

    Full Text Available Background: Diagnosis of kidney scar could prevent vesico urethral reflax and its complications such as hypertension and renal failure. This study was conducted to determine average kidney length and volume in infants by sonography to accurate diagnosis of scars.Methods: This study was conducted on infants with the history of UTI who referred to Imam Reza Hospital, Kermanshah Iran, for DMSA scan. They underwent kidney sonography before DMSA scan. Difference in kidney length and volume were calculated and data was recorded and were analyzed using statistical tests.Results: Right kidney length was less than left in 60% of right kidney scars this rate was 77.8% in nonscar patients (P=0.657. Left kidney length was less than right in 50% of left kidney scar and that was 22% in nonscar patients (P=0.241. Kidney volume was smaller than other side in 55.6% of right kidney scar and 62.5% of left kidney scar. Higher length detected in 100% and 47% of right and left kidney inflammation respectively. Higher volume detected in 40% and 76.5% of right and left kidney inflammation.Conclusion: In comparison with other studies suggesting kidney length as a valuble predictor for diagnosis of scar we did not find any relationship between scar and kidney length or volume.

  1. A new theory to evaluate the critical length for fracture propagation in snow

    Science.gov (United States)

    Gaume, Johan; van Herwijnen, Alec; Chambon, Guillaume; Wever, Nander; Schweizer, Jürg

    2016-04-01

    The failure of a weak snow layer buried below cohesive slab layers is a necessary, but insufficient condition for the release of a dry-snow slab avalanche. The size of the crack in the weak layer must also exceed a critical length to propagate over a wide surface. In contrast to founding shear-based approaches, the recent anticrack model accounts for weak layer collapse and allows to better explain typical observations of remote triggering from flat areas. However, the latter model predicts that the critical length for crack propagation is independent of slope angle, a rather surprising and counterintuitive result. Our new mechanical model reconciles past approaches by considering for the first time the complex interplay between slab elasticity, the failure envelope of the weak layer and its structural collapse. We were able to reproduce crack propagation on flat terrain and the decrease of the critical length with slope angle observed in numerical experiments. Furthermore, we show that the anticrack model only works on flat terrain and significantly overestimates the critical crack length for steep slopes where most avalanches are triggered. This important limitation is due to strong and unfounded assumptions concerning the weak layer which is treated as a purely rigid material with a slope-independent failure criterion. The good agreement of our new model with extensive field data and its successful implementation in the snow cover model SNOWPACK opens promising prospect to improve avalanche forecasting.

  2. Bag-of-steps : Predicting lower-limb fracture rehabilitation length

    NARCIS (Netherlands)

    Pla, Albert; López, Beatriz; Nogueira, Cristofor; Mordvaniuk, Natalia; Blokhuis, Taco J.; Holtslag, Herman R.

    2016-01-01

    This paper presents bag-of-steps, a new methodology to predict the rehabilitation length of a patient by monitoring the weight he is bearing in his injured leg and using a predictive model based on the bag-of-words technique. A force sensor is used to monitor and characterize the patient's gait, obt

  3. The effects of volume percent and aspect ratio of carbon fiber on fracture toughness of reinforced aluminum matrix composites

    Energy Technology Data Exchange (ETDEWEB)

    Naji, H. [Department of Materials and Metallurgical Engineering, Engineering Faculty, Ferdowsi University of Mashhad, Azadi Square, P.O. Box 91775-1111 (Iran, Islamic Republic of); Zebarjad, S.M. [Department of Materials and Metallurgical Engineering, Engineering Faculty, Ferdowsi University of Mashhad, Azadi Square, P.O. Box 91775-1111 (Iran, Islamic Republic of)], E-mail: Zebarjad@ferdowsi.um.ac.ir; Sajjadi, S.A. [Department of Materials and Metallurgical Engineering, Engineering Faculty, Ferdowsi University of Mashhad, Azadi Square, P.O. Box 91775-1111 (Iran, Islamic Republic of)

    2008-07-15

    Carbon fiber reinforced aluminum matrix composites are used as advanced materials in aerospace and electronic industries. In order to investigate role of aspect ratio of carbon fiber on fracture toughness of aluminum matrix composite, the composite was produced using stir casting. Al-8.5%Si-5%Mg selected as a matrix. The samples were prepared with three volume fractions (1, 2 and 3) and three aspect ratios (300, 500 and 800). Three-point bending test was performed on the specimens to evaluate the fracture toughness of the materials. The results showed that the fracture toughness of composites depends on both fiber volume fraction and aspect ratio. Scanning electron microscopy (SEM) was employed to elucidate the fracture behavior and crack deflection of composites. The study also, showed that the toughening mechanism depends strongly on fiber volume fraction, aspect ratio and the degree of wetting between fiber and matrix.

  4. Study of a flight monitor for jet engine disk cracks using the critical length criterion of fracture mechanics

    Science.gov (United States)

    Barranger, J. P.

    1974-01-01

    A disk crack detector is discussed which is intended to operate while in flight. The crack detector monitors the disk rim for radial surface cracks emanating from the blade root interface. An eddy current type sensor with a remotely located capacitance-resistance bridge and signal analyzer is able to detect reliably a simulated crack 1/8 in. long. The sensor was tested at rim velocities of 600 fps and at 1000 F. Fracture mechanics is used to calculate the critical crack length. Knowledge of the crack growth rate permits the calculation of the number of stress cycles remaining for the detected crack to grow to critical size. A plot is presented of the remaining life as a function of the critical crack length and the operating stress. It is shown that for a disk of Inconel 718 a through-the-thickness crack operating under a rim stress of 50 kpsi has a critical length of 0.7-in. and a remaining life of 130 flights.

  5. 'Orbital volume restoration rate after orbital fracture'; a CT-based orbital volume measurement for evaluation of orbital wall reconstructive effect.

    Science.gov (United States)

    Wi, J M; Sung, K H; Chi, M

    2017-01-13

    PurposeTo evaluate the effect of orbital reconstruction and factors related to the effect of orbital reconstruction by assessing of orbital volume using orbital computed tomography (CT) in cases of orbital wall fracture.MethodsIn this retrospective study, 68 patients with isolated blowout fractures were evaluated. The volumes of orbits and herniated orbital tissues were determined by CT scans using a three-dimensional reconstruction technique (the Eclipse Treatment Planning System). Orbital CT was performed preoperatively, immediately after surgery, and at final follow ups (minimum of 6 months). We evaluated the reconstructive effect of surgery making a new formula, 'orbital volume reconstruction rate' from orbital volume differences between fractured and contralateral orbits before surgery, immediately after surgery, and at final follow up.ResultsMean volume of fractured orbits before surgery was 23.01±2.60 cm(3) and that of contralateral orbits was 21.31±2.50 cm(3) (P=0.005). Mean volume of the fractured orbits immediately after surgery was 21.29±2.42 cm(3), and that of the contralateral orbits was 21.33±2.52 cm(3) (P=0.921). Mean volume of fractured orbits at final follow up was 21.50±2.44 cm(3), and that of contralateral orbits was 21.32±2.50 cm(3) (P=0.668). The mean orbital volume reconstruction rate was 100.47% immediately after surgery and 99.17% at final follow up. No significant difference in orbital volume reconstruction rate was observed with respect to fracture site or orbital implant type. Patients that underwent operation within 14 days of trauma had a better reconstruction rate at final follow up than patients who underwent operation over 14 days after trauma (P=0.039).ConclusionComputer-based measurements of orbital fracture volume can be used to evaluate the reconstructive effect of orbital implants and provide useful quantitative information. Significant reduction of orbital volume is observed immediately after orbital wall

  6. Instantaneous equations for multiphase flow in porous media without length-scale restrictions using a non-local averaging volume

    Energy Technology Data Exchange (ETDEWEB)

    Espinosa-Paredes, Gilberto, E-mail: gepe@xanum.uam.m [Area de Ingenieria en Recursos Energeticos, Universidad Autonoma Metropolitana-Iztapalapa, Av. San Rafael Atlixco 186, Col. Vicentina, Apartado Postal 55-535, Mexico D.F. 09340 (Mexico)

    2010-05-15

    The aim of this paper is to propose a framework to obtain a new formulation for multiphase flow conservation equations without length-scale restrictions, based on the non-local form of the averaged volume conservation equations. The simplification of the local averaging volume of the conservation equations to obtain practical equations is subject to the following length-scale restrictions: d << l << L, where d is the characteristic length of the dispersed phases, l is the characteristic length of the averaging volume, and L is the characteristic length of the physical system. If the foregoing inequality does not hold, or if the scale of the problem of interest is of the order of l, the averaging technique and therefore, the macroscopic theories of multiphase flow should be modified in order to include appropriate considerations and terms in the corresponding equations. In these cases the local form of the averaged volume conservation equations are not appropriate to describe the multiphase system. As an example of the conservation equations without length-scale restrictions, the natural circulation boiling water reactor was consider to study the non-local effects on the thermal-hydraulic core performance during steady-state and transient behaviors, and the results were compared with the classic local averaging volume conservation equations.

  7. Flight monitor for jet engine disk cracks and the use of critical length criterion of fracture mechanics

    Science.gov (United States)

    Barranger, J. P.

    1973-01-01

    A disk crack detector is discussed which is intended to operate under flight conditions. It monitors the disk rim for surface cracks emanating from the blade root interface. An eddy current type sensor, with a remotely located capacitance/conductance bridge and signal analyzer, can reliably detect a simulated crack 3 mm long. The sensor was tested on a spinning turbine disk at 540 C. Tests indicate that the system is useful at disk rim velocities to 460 m/sec. By using fracture mechanics, it is shown for Inconel 718 th at a crack operating under a rim stress of 34 x ten to the 7th power N/sqm has a critical length of 18 mm.

  8. Studies on effect of pre-crack length variation on Inter-laminar fracture toughness of a Glass Epoxy laminated composite

    Science.gov (United States)

    Huddhar, Arun; Desai, Abilash; Sharanaprabhu, C. M.; Kudari, Shashidhar K.; Shivakumar Gouda, P. S.

    2016-09-01

    Laminates of fiber reinforced polymer composites are good in in-plane properties and inherently weak in through thickness direction. To address this through thickness properties, the inter-laminar fracture toughness (GIc and GIIc) of a unidirectional (UD) Glass epoxy composite laminates were subjected to Mode-I and Mode-II loadings. Experiments were conducted using Double cantilever beam (DCB) and End notch flexure (ENF) specimens with varying pre-crack lengths. Mode I energy release rate (GIc) were also evaluated with modified beam and modified compliance theories. The experimental results reveal that, GIc fracture toughness increases with increasing in pre-crack length, where as in GIIc the effect of increase in pre-crack length exhibits reduced fracture toughness.

  9. Chain length distributions in linear polyaddition proceeding in nano-scale small volumes without mass transfer

    Science.gov (United States)

    Szymanski, R.; Sosnowski, S.

    2017-01-01

    Computer simulations (Monte Carlo and numerical integration of differential equations) and theoretical analysis show that the statistical nature of polyaddition, both irreversible and reversible one, affects the way the macromolecules of different lengths are distributed among the small volume nano-reactors (droplets in this study) at any reaction time. The corresponding droplet distributions in respect to the number of reacting chains as well as the chain length distributions depend, for the given reaction time, on rate constants of polyaddition kp and depolymerization kd (reversible process), and the initial conditions: monomer concentration and the number of its molecules in a droplet. As a model reaction, a simple polyaddition process (M)1+(M)1 ⟶ ⟵ (M)2 , (M)i+(M)j ⟶ ⟵ (M)i+j was chosen, enabling to observe both kinetic and thermodynamic (apparent equilibrium constant) effects of a small number of reactant molecules in a droplet. The average rate constant of polymerization is lower than in a macroscopic system, depending on the average number of reactant molecules in a droplet. The apparent equilibrium constants of polymerization Ki j=[(M)i +j] ¯ /([(M)i] ¯ [(M)j] ¯ ) appear to depend on oligomer/polymer sizes as well as on the initial number of monomer molecules in a droplet. The corresponding equations, enabling prediction of the equilibrium conditions, were derived. All the analyzed effects are observed not only for ideally dispersed systems, i.e. with all droplets containing initially the same number of monomer (M)1 molecules, but also when initially the numbers of monomer molecules conform the Poisson distribution, expected for dispersions of reaction mixtures.

  10. Longer leukocyte telomere length is associated with smaller hippocampal volume among non-demented APOE ε3/ε3 subjects.

    Directory of Open Access Journals (Sweden)

    Mikael Wikgren

    Full Text Available Telomere length shortens with cellular division, and leukocyte telomere length is used as a marker for systemic telomere length. The hippocampus hosts adult neurogenesis and is an important structure for episodic memory, and carriers of the apolipoprotein E ε4 allele exhibit higher hippocampal atrophy rates and differing telomere dynamics compared with non-carriers. The authors investigated whether leukocyte telomere length was associated with hippocampal volume in 57 cognitively intact subjects (29 ε3/ε3 carriers; 28 ε4 carriers aged 49-79 yr. Leukocyte telomere length correlated inversely with left (r(s = -0.465; p = 0.011, right (r(s = -0.414; p = 0.025, and total hippocampus volume (r(s = -0.519; p = 0.004 among APOE ε3/ε3 carriers, but not among ε4 carriers. However, the ε4 carriers fit with the general correlation pattern exhibited by the ε3/ε3 carriers, as ε4 carriers on average had longer telomeres and smaller hippocampi compared with ε3/ε3 carriers. The relationship observed can be interpreted as long telomeres representing a history of relatively low cellular proliferation, reflected in smaller hippocampal volumes. The results support the potential of leukocyte telomere length being used as a biomarker for tapping functional and structural processes of the aging brain.

  11. Length and volume of morphologically normal kidneys in Korean Children: Ultrasound measurement and estimation using body size

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jun Hwee; Kim, Myung Joon; Lim, Sok Hwan; Lee, Mi Jung [Dept. of Radiology and Research Institute of Radiological Science, Severance Children' s Hospital, Yonsei University College of Medicine, Seoul (Korea, Republic of); Kim, Ji Eun [Biostatistics Collaboration Unit, Yonsei University College of Medicine, Seoul (Korea, Republic of)

    2013-08-15

    To evaluate the relationship between anthropometric measurements and renal length and volume measured with ultrasound in Korean children who have morphologically normal kidneys, and to create simple equations to estimate the renal sizes using the anthropometric measurements. We examined 794 Korean children under 18 years of age including a total of 394 boys and 400 girls without renal problems. The maximum renal length (L) (cm), orthogonal anterior-posterior diameter (D) (cm) and width (W) (cm) of each kidney were measured on ultrasound. Kidney volume was calculated as 0.523 x L x D x W (cm{sup 3}). Anthropometric indices including height (cm), weight (kg) and body mass index (m{sup 2}/kg) were collected through a medical record review. We used linear regression analysis to create simple equations to estimate the renal length and the volume with those anthropometric indices that were mostly correlated with the US-measured renal sizes. Renal length showed the strongest significant correlation with patient height (R2, 0.874 and 0.875 for the right and left kidneys, respectively, p < 0.001). Renal volume showed the strongest significant correlation with patient weight (R2, 0.842 and 0.854 for the right and left kidneys, respectively, p < 0.001). The following equations were developed to describe these relationships with an estimated 95% range of renal length and volume (R2, 0.826-0.884, p < 0.001): renal length = 2.383 + 0.045 x Height (± 1.135) and = 2.374 + 0.047 x Height (± 1.173) for the right and left kidneys, respectively; and renal volume 7.941 + 1.246 x Weight (± 15.920) and = 7.303 + 1.532 x Weight (± 18.704) for the right and left kidneys, respectively. Scatter plots between height and renal length and between weight and renal volume have been established from Korean children and simple equations between them have been developed for use in clinical practice.

  12. Assessment of humeral length in dogs after repair of Salter-Harris type IV fracture of the lateral part of the humeral condyle.

    Science.gov (United States)

    Lefebvre, Jean-Benoit G N G; Robertson, Thomas R A; Baines, Stephen J; Jeffery, Nicholas D; Langley-Hobbs, Sorrel J

    2008-08-01

    To evaluate the effect of fracture and subsequent repair on future bone growth of the humerus after Salter-Harris type IV fracture of the lateral part of the humeral condyle (LPHC). Prospective study. Dogs (n=11). Dogs that had LPHC fracture and an open distal humeral physis repaired (1992-2006) were re-examined and radiographed at >or=12 months of age and humeral length was measured. Measurements from 11 dogs showed a significant (P=.02) increase in length of the humeral diaphysis of the affected leg compared with that of the intact limb (median, 1.2%; range, 1.3-3.4%). Condylar deformity secondary to growth disturbance was not observed. Shortening or growth deformity was not observed after fracture and repair even if a transcondylar screw was placed through the distal humeral growth plate. A mild overgrowth of the humeral diaphysis was observed, although likely considered clinically unimportant. Fracture of the LPHC and subsequent repair in dogs >3 months of age do not impair growth of the humeral diaphysis. A transcondylar humeral screw placed through the humeral physis will not result in shortening of the humeral diaphysis. Implant removal to allow for further growth is therefore not indicated.

  13. Community-based risk assessment of water contamination from high-volume horizontal hydraulic fracturing.

    Science.gov (United States)

    Penningroth, Stephen M; Yarrow, Matthew M; Figueroa, Abner X; Bowen, Rebecca J; Delgado, Soraya

    2013-01-01

    The risk of contaminating surface and groundwater as a result of shale gas extraction using high-volume horizontal hydraulic fracturing (fracking) has not been assessed using conventional risk assessment methodologies. Baseline (pre-fracking) data on relevant water quality indicators, needed for meaningful risk assessment, are largely lacking. To fill this gap, the nonprofit Community Science Institute (CSI) partners with community volunteers who perform regular sampling of more than 50 streams in the Marcellus and Utica Shale regions of upstate New York; samples are analyzed for parameters associated with HVHHF. Similar baseline data on regional groundwater comes from CSI's testing of private drinking water wells. Analytic results for groundwater (with permission) and surface water are made publicly available in an interactive, searchable database. Baseline concentrations of potential contaminants from shale gas operations are found to be low, suggesting that early community-based monitoring is an effective foundation for assessing later contamination due to fracking.

  14. Water-soluble gases as partitioning tracers to investigate the pore volume?transmissivity correlation in a fracture

    Science.gov (United States)

    Lunati, Ivan; Kinzelbach, Wolfgang

    2004-11-01

    Hydraulically equivalent fractures may show striking differences when a gas-migration experiment is performed because of the different correlations between transmissivity, pore volume and entry pressure. We numerically simulate gas migration between injection and extraction boreholes in a parallel plate fracture with a heterogeneous fault gouge, in a rough-walled fracture filled with homogeneous material, and in a rough-walled empty fracture. The parallel plate model and the empty model clearly show the existence of preferential paths; for high variance of the transmissivity field, gas flow takes place only in few discrete channels separated by water-saturated regions. In contrast, in the fracture filled with homogeneous fault gouge, the gas saturation is continuous and more uniformly distributed. It appears a fundamental issue to be able to discriminate in situ among conceptual models that can yield such a different gas-saturation distribution. As in practice, the saturation distribution cannot be directly observed, tracer experiments are performed to characterize a fracture. For these reasons, we simulate the transport of tracers, which are added to the gas phase as soon as quasi-steady saturation distribution and extraction rate are achieved, and we compare the breakthrough curves obtained assuming different models. Our numerical simulations suggest that discrimination among the models on the basis of single-tracer tests is unlikely. A better tool to investigate fracture properties is provided by a gas-tracer test, in which a cocktail of gases with different water solubility is employed. These gases behave as partitioning tracers and allow us to estimate the gas saturation in the fracture. Indeed, by comparison of the residence-time distributions of different gases, we are able to compute a streamline effective saturation, which is an excellent estimate of fracture saturation. In addition, the streamline effective saturation curve contains information that is

  15. Implicit Finite Volume and Discontinuous Galerkin Methods for Multicomponent Flow in Unstructured 3D Fractured Porous Media

    CERN Document Server

    Moortgat, Joachim; Soltanian, Mohamad Reza

    2016-01-01

    We present a new implicit higher-order finite element (FE) approach to efficiently model compressible multicomponent fluid flow on unstructured grids and in fractured porous subsurface formations. The scheme is sequential implicit: pressures and fluxes are updated with an implicit Mixed Hybrid Finite Element (MHFE) method, and the transport of each species is approximated with an implicit second-order Discontinuous Galerkin (DG) FE method. Discrete fractures are incorporated with a cross-flow equilibrium approach. This is the first investigation of all-implicit higher-order MHFE-DG for unstructured triangular, quadrilateral (2D), and hexahedral (3D) grids and discrete fractures. A lowest-order implicit finite volume (FV) transport update is also developed for the same grid types. The implicit methods are compared to an Implicit-Pressure-Explicit-Composition (IMPEC) scheme. For fractured domains, the unconditionally stable implicit transport update is shown to increase computational efficiency by orders of mag...

  16. Rest interval between resistance exercise sets: length affects volume but not creatine kinase activity or muscle soreness.

    Science.gov (United States)

    Evangelista, Renato; Pereira, Rafael; Hackney, Anthony C; Machado, Marco

    2011-03-01

    To compare differences between two different rest interval lengths between sets on the volume completed, muscle damage and muscle soreness during a resistance exercise bout. Twenty-eight healthy sedentary men (18 ± 1 y old) volunteered to participate in this study and were divided into the 1 min (1RI; n = 14) or 3 min (3RI; n = 14) rest interval length between sets. They were submitted to maximal voluntary isometric contraction strength (MVC) and then performed a resistance exercise protocol constituted for three sets of biceps curl at 40% of MVC with 1 min (1RI group) or 3 min (3RI group) interval length between sets. Each bout was performed to voluntary fatigue and the workout volume completed was calculated. Subjects provided blood samples before each bout, and at 24, and 48 h following exercise to evaluate serum CK activity. Muscle soreness was analyzed through visual analog scale, which was presented to subjects before first bout, immediately after exercise protocol and at 24, and 48 h following exercise. The results demonstrated that the subjects with longer rest intervals provide greater workout volume as expected, but there were no differences in serum CK activity and muscle soreness between groups. Training with high-volume, low-intensity resistance training, exercising with short rest intervals does not appear to present any additional challenge to recovery in untrained subjects.

  17. Modeling Atmospheric Emissions and Calculating Mortality Rates Associated with High Volume Hydraulic Fracturing Transportation

    Science.gov (United States)

    Mathews, Alyssa

    Emissions from the combustion of fossil fuels are a growing pollution concern throughout the global community, as they have been linked to numerous health issues. The freight transportation sector is a large source of these emissions and is expected to continue growing as globalization persists. Within the US, the expanding development of the natural gas industry is helping to support many industries and leading to increased transportation. The process of High Volume Hydraulic Fracturing (HVHF) is one of the newer advanced extraction techniques that is increasing natural gas and oil reserves dramatically within the US, however the technique is very resource intensive. HVHF requires large volumes of water and sand per well, which is primarily transported by trucks in rural areas. Trucks are also used to transport waste away from HVHF well sites. This study focused on the emissions generated from the transportation of HVHF materials to remote well sites, dispersion, and subsequent health impacts. The Geospatial Intermodal Freight Transport (GIFT) model was used in this analysis within ArcGIS to identify roadways with high volume traffic and emissions. High traffic road segments were used as emissions sources to determine the atmospheric dispersion of particulate matter using AERMOD, an EPA model that calculates geographic dispersion and concentrations of pollutants. Output from AERMOD was overlaid with census data to determine which communities may be impacted by increased emissions from HVHF transport. The anticipated number of mortalities within the impacted communities was calculated, and mortality rates from these additional emissions were computed to be 1 in 10 million people for a simulated truck fleet meeting stricter 2007 emission standards, representing a best case scenario. Mortality rates due to increased truck emissions from average, in-use vehicles, which represent a mixed age truck fleet, are expected to be higher (1 death per 341,000 people annually).

  18. Variation in access to community rehabilitation services and length of stay in hospital following a hip fracture: a cross-sectional study

    Science.gov (United States)

    Neuburger, Jenny; Harding, Karen A; Bradley, Rachel J D; Cromwell, David A; Gregson, Celia L

    2014-01-01

    Objectives To assess variation in access to and use of community rehabilitation services for patients with a hip fracture, and whether this affects length of stay in hospital. Design Cross-sectional study using administrative patient-level data from Hospital Episode Statistics (HES) and organisational survey data. Setting A regional health economy in South West England served by four acute National Health Service (NHS) hospital trusts and six former Primary Care Trusts (PCTs). Population 1230 hip fracture patients treated in an acute hospital between 1 April 2011 and 29 February 2012. Main outcomes Information about access to community rehabilitation services for each acute hospital and PCT, reported by organisational survey. Rates of patients transferred from acute hospital to community rehabilitation hospitals (CRH) across eight groups with varying access; determined by acute hospital and PCT. Median lengths of stay in the acute hospital, and in the acute hospital plus CRH combined. Associations between the rate of transfer to a CRH and median lengths of stay assessed using Spearman's rank correlation coefficient (rs). Results Access to community rehabilitation services varied, including the number of CRH inpatient beds, formal access criteria and waiting times. In one PCT, no home-based rehabilitation service was available. The percentage of patients transferred to a CRH ranged from 2.1% to 54.7%. A higher transfer rate was associated with a shorter median length of stay in the acute hospital (rs=−0.8; p=0.01), but a longer median combined length of stay in the acute hospital and CRH (rs=+0.7; p=0.04). Conclusions Within one geographical area, there was wide variation in availability and use of community rehabilitation services for patients discharged from an acute hospital following a hip fracture. Reliance on transfers to community rehabilitation hospitals was associated with a longer length of stay in the NHS. PMID:25208849

  19. The use of LiDCO based fluid management in patients undergoing hip fracture surgery under spinal anaesthesia: Neck of femur optimisation therapy - targeted stroke volume (NOTTS: study protocol for a randomized controlled trial

    Directory of Open Access Journals (Sweden)

    Moran Chris G

    2011-09-01

    Full Text Available Abstract Background Approximately 70,000 patients/year undergo surgery for repair of a fractured hip in the United Kingdom. This is associated with 30-day mortality of 9% and survivors have a considerable length of acute hospital stay postoperatively (median 26 days. Use of oesophageal Doppler monitoring to guide intra-operative fluid administration in hip fracture repair has previously been associated with a reduction in hospital stay of 4-5 days. Most hip fracture surgery is now performed under spinal anaesthesia. Oesophageal Doppler monitoring may be unreliable in the presence of spinal anaesthesia and most patients would not tolerate the probes. An alternative method of guiding fluid administration (minimally-invasive arterial pulse contour analysis has been shown to reduce length of stay in high-risk surgical patients but has never been studied in hip fracture surgery. Methods Single-centre randomised controlled parallel group trial. Randomisation by website using computer generated concealed tables. Setting: University hospital in UK. Participants: 128 patients with acute primary hip fracture listed for operative repair under spinal anaesthesia and aged > 65 years. Intervention: Stroke volume guided intra-operative fluid management. Continuous measurement of SV recorded by a calibrated cardiac output monitor (LiDCOplus. Maintenance fluid and 250 ml colloid boluses given to achieve sustained 10% increases in stroke volume. Control group: fluid administration at the responsible (blinded anaesthetist's discretion. The intervention terminates at the end of the surgical procedure and post-operative fluid management is at the responsible anaesthetist's discretion. Primary outcome: length of acute hospital stay is determined by a blinded team of clinicians. Secondary outcomes include number of complications and total cost of care. Funding NIHR/RfPB: PB-PG-0407-13073. Trial registration number Trial registration: Current Controlled Trials ISRCTN

  20. FLIS Procedures Manual. Document Identifier Code Input/Output Formats (Fixed Length). Volume 8.

    Science.gov (United States)

    2007-11-02

    4100.39-M DEFENSE LOGISTICS SERVICES CENTER Volume 8 74 WASHINGTON AVE N BATTLE CREEK MI 49017-3084 DLSC- VPH 1 April 1997 FOREWORD This is one of the...volume 1, chapter 1.6, or administrative comments and inquiries may be directed to DLSC- VPH . Service/Agency distribution is handled through...changes to DLSC- VPH . Content changes appearing on these pages are entered in bold-faced italic type. Comments or questions may be directed to DLSC- VPH . This

  1. Implicit finite volume and discontinuous Galerkin methods for multicomponent flow in unstructured 3D fractured porous media

    Science.gov (United States)

    Moortgat, Joachim; Amooie, Mohammad Amin; Soltanian, Mohamad Reza

    2016-10-01

    We present a new implicit higher-order finite element (FE) approach to efficiently model compressible multicomponent fluid flow on unstructured grids and in fractured porous subsurface formations. The scheme is sequential implicit: pressures and fluxes are updated with an implicit Mixed Hybrid Finite Element (MHFE) method, and the transport of each species is approximated with an implicit second-order Discontinuous Galerkin (DG) FE method. Discrete fractures are incorporated with a cross-flow equilibrium approach. This is the first investigation of all-implicit higher-order MHFE-DG for unstructured triangular, quadrilateral (2D), and hexahedral (3D) grids and discrete fractures. A lowest-order implicit finite volume (FV) transport update is also developed for the same grid types. The implicit methods are compared to an Implicit-Pressure-Explicit-Composition (IMPEC) scheme. For fractured domains, the unconditionally stable implicit transport update is shown to increase computational efficiency by orders of magnitude as compared to IMPEC, which has a time-step constraint proportional to the pore volume of discrete fracture grid cells. However, when lowest-order Euler time-discretizations are used, numerical errors increase linearly with the larger implicit time-steps, resulting in high numerical dispersion. Second-order Crank-Nicolson implicit MHFE-DG and MHFE-FV are therefore presented as well. Convergence analyses show twice the convergence rate for the DG methods as compared to FV, resulting in two to three orders of magnitude higher computational efficiency. Numerical experiments demonstrate the efficiency and robustness in modeling compressible multicomponent flow on irregular and fractured 2D and 3D grids, even in the presence of fingering instabilities.

  2. Spatial distribution of soluble insulin in pig subcutaneous tissue: Effect of needle length, injection speed and injected volume.

    Science.gov (United States)

    Thomsen, Maria; Rasmussen, Christian Hove; Refsgaard, Hanne H F; Pedersen, Karen-Margrethe; Kirk, Rikke K; Poulsen, Mette; Feidenhans'l, Robert

    2015-11-15

    The spatial distribution of a soluble insulin formulation was visualized and quantified in 3-dimensions using X-ray computed tomography. The drug distribution was visualized for ex vivo injections in pig subcutaneous tissue. Pig subcutaneous tissue has very distinct layers, which could be separated in the tomographic reconstructions and the amount of drug in each tissue class was quantified. With a scan time of about 45min per sample, and a robust segmentation it was possible to analyze differences in the spatial drug distribution between several similar injections. It was studied how the drug distribution was effected by needle length, injection speed and injected volume. For an injected volume of 0.1ml and injection depth of 8mm about 50% of the injections were partly intramuscular. Using a 5mm needle resulted in purely subcutaneous injections with minor differences in the spatial drug distribution between injections. Increasing the injected volume from 0.1ml to 1ml did not increase the intramuscular volume fraction, but gave a significantly higher volume fraction placed in the fascia separating the deep and superficial subcutaneous fat layers. Varying the injection speed from 25l/s up to 300l/s gave no changes in the drug concentration distribution. The method presented gives novel insight into subcutaneous injections of soluble insulin drugs and can be used to optimize the injection technique for subcutaneous drug administration in preclinical studies of rodents. Copyright © 2015 Elsevier B.V. All rights reserved.

  3. Ductile fracture toughness of modified A 302 grade B plate materials. Volume 2

    Energy Technology Data Exchange (ETDEWEB)

    McCabe, D.E.; Manneschmidt, E.T.; Swain, R.L.

    1997-02-01

    The objective of this work was to develop ductile fracture toughness data in the form of J-R curves for modified A 302 grade B plate materials typical of those used in fabricating reactor pressure vessels. A previous experimental study at Materials Engineering Associates (MEA) on one particular heat of A 302 grade B plate showed decreasing J-R curves with increased specimen thickness. This characteristic has not been observed in numerous tests made on the more recent production materials of A 533 grade B and A 508 class 2 pressure vessel steels. It was unknown if the departure from norm for the MEA material was a generic characteristic for all heats of A 302 grade B steels or just unique to that one particular plate. Seven heats of modified A 302 grade B steel and one heat of vintage A 533 grade B steel were provided to this project by the General Electric Company of San Jose, California. All plates were tested for chemical content, tensile properties, Charpy transition temperature curves, drop-weight nil-ductility transition (NDT) temperature, and J-R curves. Tensile tests were made in the three principal orientations and at four temperatures, ranging from room temperature to 550{degrees}F (288{degrees}C). Charpy V-notch transition temperature curves were obtained in longitudinal, transverse, and short transverse orientations. J-R curves were made using four specimen sizes (1/2T, IT, 2T, and 4T). None of the seven heats of modified A 302 grade showed size effects of any consequence on the J-R curve behavior. Crack orientation effects were present, but none were severe enough to be reported as atypical. A test temperature increase from 180 to 550{degrees}F (82 to 288{degrees}C) produced the usual loss in J-R curve fracture toughness. Generic J-R curves and mathematical curve fits to the same were generated to represent each heat of material. This volume is a compilation of all data developed.

  4. Production decline analysis for a multi-fractured horizontal well considering elliptical reservoir stimulated volumes in shale gas reservoirs

    Science.gov (United States)

    Wei, Mingqiang; Duan, Yonggang; Fang, Quantang; Zhang, Tiantian

    2016-06-01

    Multi-fractured horizontal wells (MFHWs) are an effective technique for developing shale gas reservoirs. After fracturing, stimulated reservoir volumes (SRVs) invariably exist around the wellbore. In this paper, a composite elliptical SRV model for each hydraulic fracturing stage is established, based on micro-seismic events. Both the SRV and the outer regions are assumed as single-porosity media with different formation physical parameters. Based on unstructured perpendicular bisection (PEBI) grids, a mathematical model considering Darcy flow, diffusion and adsorption/desorption in shale gas reservoirs is presented. The numerical solution is obtained by combining the control volume finite element method with the fully implicit method. The model is verified by a simplified model solution. The MFHW Blasingame production decline curves, which consider elliptical SRVs in shale gas reservoirs, are plotted by computer programming. The flow regions can be divided into five flow regimes: early formation linear flow, radial flow in the SRV region, transient flow, pseudo radial flow and boundary dominated flow. Finally, the effect of six related parameters, including the SRV area size, outer region permeability, SRV region permeability, Langmuir pressure, Langmuir volume and diffusion coefficient, are analyzed on type curves. The model presented in this paper can expand our understanding of MFHW production decline behaviors in shale gas reservoirs and can be applied to estimate reservoir properties, the SRV area, and reserves in these types of reservoirs by type curve matching.

  5. Discrete modeling of hydraulic fracturing processes in a complex pre-existing fracture network

    Science.gov (United States)

    Kim, K.; Rutqvist, J.; Nakagawa, S.; Houseworth, J. E.; Birkholzer, J. T.

    2015-12-01

    Hydraulic fracturing and stimulation of fracture networks are widely used by the energy industry (e.g., shale gas extraction, enhanced geothermal systems) to increase permeability of geological formations. Numerous analytical and numerical models have been developed to help understand and predict the behavior of hydraulically induced fractures. However, many existing models assume simple fracturing scenarios with highly idealized fracture geometries (e.g., propagation of a single fracture with assumed shapes in a homogeneous medium). Modeling hydraulic fracture propagation in the presence of natural fractures and homogeneities can be very challenging because of the complex interactions between fluid, rock matrix, and rock interfaces, as well as the interactions between propagating fractures and pre-existing natural fractures. In this study, the TOUGH-RBSN code for coupled hydro-mechanical modeling is utilized to simulate hydraulic fracture propagation and its interaction with pre-existing fracture networks. The simulation tool combines TOUGH2, a simulator of subsurface multiphase flow and mass transport based on the finite volume approach, with the implementation of a lattice modeling approach for geomechanical and fracture-damage behavior, named Rigid-Body-Spring Network (RBSN). The discrete fracture network (DFN) approach is facilitated in the Voronoi discretization via a fully automated modeling procedure. The numerical program is verified through a simple simulation for single fracture propagation, in which the resulting fracture geometry is compared to an analytical solution for given fracture length and aperture. Subsequently, predictive simulations are conducted for planned laboratory experiments using rock-analogue (soda-lime glass) samples containing a designed, pre-existing fracture network. The results of a preliminary simulation demonstrate selective fracturing and fluid infiltration along the pre-existing fractures, with additional fracturing in part

  6. Visualization of Gas-to-Liquid (GTL) Fuel Liquid Length and Soot Formation in the Constant Volume Combustion Chamber

    Science.gov (United States)

    Azimov, Ulugbek; Kim, Ki-Seong

    In this research, GTL spray combustion was visualized in an optically accessible quiescent constant-volume combustion chamber. The results were compared with the spray combustion of diesel fuel. Fast-speed photography with direct laser sheet illumination was used to determine the fuel liquid-phase length, and shadowgraph photography was used to determine the distribution of the sooting area in the fuel jet. The results showed that the fuel liquid-phase length of GTL fuel jets stabilized at about 20-22mm from the injector orifice and mainly depended on the ambient gas temperature and fuel volatility. GTL had a slightly shorter liquid length than that of the diesel fuel. This tendency was also maintained when multiple injection strategy was applied. The penetration of the tip of the liquid-phase fuel during pilot injection was a little shorter than the penetration during main injection. The liquid lengths during single and main injections were identical. In the case of soot formation, the results showed that soot formation was mainly affected by air-fuel mixing, and had very weak dependence on fuel volatility.

  7. Glacier length, area and volume changes in the Himalaya: an overview and specific examples

    Science.gov (United States)

    Bolch, T.; Bhambri, R.; Kamp, U.; Pieczonka, T.

    2011-12-01

    The Himalaya comprises one of the largest glacier-covered areas outside the polar regions. Glaciers are of special interest for several reasons. For instance, receding glaciers can cause the development of hazardous glacial lakes and glaciers contribute to the overall river runoff. The importance of the glacier melt to run off, however, varies significantly depending especially on the precipitation regime. Previous studies indicate that the vast majority of the Himalayan glaciers retreated during the recent decades with only few exemptions. Although the numbers of investigates glaciers increased in the last few years, there is still a lack of knowledge about the glacier behaviour in the different regions of the Himalaya. Existing length measurements in the Indian Himalaya show continuous retreat with an accelerating trend in recent years for most of the glaciers. The annual retreat rates vary between ~5m and more than 50m. However, several measurements are based on topographic maps or coarse satellite data and can have therefore higher uncertainties. Own reassessments for the debris-covered Gangotri Glacier situated in Garhwal Himalaya/western India based on high resolution imagery such as Corona, Hexagon, IRS PAN, LISS IV, and Cartosat-1 show an continuous retreat with an average rate of 19.9 ± 0.3 m a-1 from 1965 to 2006. This is significant but less than previously published. Similar results were revealed for the area changes in upper Alaknanda and Bhagirathi valleys in Garhwal Himalaya. We found a lower but still significant area loss of 4.6 ± 2.8 % between 1968 and 2006. Area changes in Khumbu Himalaya/Nepal are with ~5% between 1962 and 2005 comparable. Investigations in the Greater Himalayan Range in southern Ladakh/northwest India revealed a general receding trend but with some of the larger glaciers with high altitude catchments being stable or even advancing. Preliminary results for Shyok Valley (Jammu and Kashmir) show on average stable or slightly

  8. Retraction notice to: influence of post fit and post length on fracture resistance: an in vitro study. J Contemp Dent Pract 2013;14(3):496-500.

    Science.gov (United States)

    2013-09-01

    It has been notified to the Editorial Board, The Journal of Contemporary Dental Practice (JCDP), that considerable script of the aforementioned article has been plagiarized from the article: Büttel L, Krastl G, Lorch H, Naumann M, Zitzmann NU, Weiger R. Influence of Post Fit and Post Length on Fracture Resistance. Int Endod J 2009;42(1):47-53. The same was confirmed after thorough evaluation and interpretation. In accordance to observe serious view in case of plagiarism, the Editorial Board, JCDP decided to take appropriate action against the act. Thus, it is herewith decided by the Editorial Board, JCDP to retract the title as addressed from the assigned issue.

  9. Atomistic simulation study of the effect of martensitic transformation volume change on crack-tip material evolution and fracture toughness

    Energy Technology Data Exchange (ETDEWEB)

    Grujicic, M. [Clemson Univ., SC (United States). Dept. of Mechanical Engineering; Lai, S.G. [Clemson Univ., SC (United States). Dept. of Mechanical Engineering; Gumbsch, P. [Max Planck-Institut fur Metallforshung Institut fuer Werstoffwissenshaft, Seestrasse 92, D-7000 Stuttgart I (Germany)

    1997-07-15

    The effect of the sign of the F.C.C.{yields}B.C.C. martensitic transformation volume change in Fe-20Ni on material evolution in a region surrounding the crack tip and the accompanying change in the fracture resistance of the material have been investigated using molecular dynamics simulations. The interaction between atoms has been modeled using the embedded atom method (EAM) interatomic potentials. To obtain both the positive and the negative values of the transformation volume change, small adjustments had to be made in the EAM functions. These changes did not significantly affect of the key materials properties, such as the relative thermodynamic stability of the F.C.C. and B.C.C. structures, elastic constants, (11 anti 2){sub bcc} twin boundary energy, (10 anti 1){sub fcc}/(1 anti 21){sub bcc} interfacial energy, etc. The simulation results show that the sign of the transformation volume change has a profound effect on the material evolution and the path of the advancing crack. When the volume change is negative, the region ahead of the crack tip undergoes the transformation only after the other regions around the crack tip have already transformed. The crack tip undergoes a significant blunting and tends to stay on the original crack plane. In sharp contrast, when the volume change is positive, the region ahead of the crack tip transforms first and significant decohesion along the F.C.C./B.C.C. interfaces takes place. Consequently the crack tends to branch out. The effect of material evolution at the crack tip on the ability of the material to withstand further fracture has been quantified by calculating the Eshelby`s F{sub 1} conservation integral. The sign of the transformation volume change is found to have a major effect on the change of the F{sub 1} integral with the simulation time. (orig.)

  10. Volume Continuation of potential fields from the minimum-length solution: An optimal tool for continuation through general surfaces

    Science.gov (United States)

    Mastellone, Daniela; Fedi, Maurizio; Ialongo, Simone; Paoletti, Valeria

    2014-12-01

    Many methods have been used to upward continue potential field data. Most techniques employ the Fast Fourier transform, which is an accurate, quick way to compute level-to-level upward continuation or spatially varying scale filters for level-to-draped surfaces. We here propose a new continuation approach based on the minimum-length solution of the inverse potential field problem, which we call Volume Continuation (VOCO). For real data the VOCO is obtained as the regularized solution to the Tikhonov problem. We tested our method on several synthetic examples involving all types of upward continuation and downward continuation (level-to-level, level-to-draped, draped-to-level, draped-to-draped). We also employed the technique to upward continue to a constant height (2500 m a.s.l.), the high-resolution draped aeromagnetic data of the Ischia Island in Southern Italy. We found that, on the average, they are consistent with the aeromagnetic regional data measured at the same altitude. The main feature of our method is that it does not only provide continued data over a specified surface, but it yields a volume of upward continuation. For example, the continued data refers to a volume and thus, any surface may be easily picked up within the volume to get upward continuation to different surfaces. This approach, based on inversion of the measured data, tends to be especially advantageous over the classical techniques when dealing with draped-to-level upward continuation. It is also useful to obtain a more stable downward continuation and to continue noisy data. The inversion procedure involved in the method implies moderate computational costs, which are well compensated by getting a 3D set of upward continued data to achieve high quality results.

  11. Normal values for renal parenchymal volume and kidney length as measured by non-enhanced multidetector spiral computed tomography

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Fei; Wu, Xiao Hou (Dept. of Urology, The First Affiliated Hospital of Chongqing Medical Univ., Chongqing (China)), email: wuxiaohou@yahoo.com; Yang, Mei (Inst. of Neuroscience, Chongqing Medical Univ., Chongqing (China)); Luo, Chun Li (Dept. of Laboratory Medicine, Chongqing Medical Univ., Chongqing (China)); Pang, Hua (Dept. of Radiology, The First Affiliated Hospital of Chongqing Medical Univ., Chongqing (China))

    2011-07-15

    Background: Renal parenchymal volume (RPV) is considered an important index for clinical decisions. However, normal values have not been established, which hinders the clinical application of RPV. Purpose: To test the accuracy and reproducibility of RPV and to investigate the normal values of RPV and kidney length as measured by non-enhanced multidetector computed tomography (CT). Material and Methods: An animal model study was performed to test the accuracy and repeatability of RPV measured by CT. RPV of porcine kidneys was measured by water displacement (actual values) and non-enhanced multidetector CT. Individual RPV and kidney length were measured by non-enhanced CT in patients with no clinical history of renal disease (n 722). Patient height, age, weight, body surface area (BSA), and body mass index (BMI) were assessed before each patient's CT examination was performed. Results: RPV obtained by the CT method was within 2% of the RPV determined by the water displacement method. The normal values of RPV (M +- 1.96 standard deviation [SD]) were 145.72 +- 54.37 mL for men and 132.46 +- 41.94 mL for women. The normal values of kidney length (M +- 1.96 SD) were 10.27 +- 1.98 cm for men and 9.93 +- 1.58 cm for women. RPV did not significantly correlate with BSA or weight in women, but correlated significantly with height and age in both men and women. Of the assessed factors age, weight, height, BSA, and BMI, age, and height were the independent factors that best reflected RPV, in both men and women. Conclusion: The present animal study results showed that non-enhanced multidetector CT findings accurately reflect the RPV. The subsequent study performed in humans showed that the RPV of the presently sampled Chinese population was lower than the commonly quoted reference values obtained from Western populations

  12. Natural thermal convection in fractured porous media

    Science.gov (United States)

    Adler, P. M.; Mezon, C.; Mourzenko, V.; Thovert, J. F.; Antoine, R.; Finizola, A.

    2015-12-01

    In the crust, fractures/faults can provide preferential pathways for fluid flow or act as barriers preventing the flow across these structures. In hydrothermal systems (usually found in fractured rock masses), these discontinuities may play a critical role at various scales, controlling fluid flows and heat transfer. The thermal convection is numerically computed in 3D fluid satured fractured porous media. Fractures are inserted as discrete objects, randomly distributed over a damaged volume, which is a fraction of the total volume. The fluid is assumed to satisfy Darcy's law in the fractures and in the porous medium with exchanges between them. All simulations were made for Rayleigh numbers (Ra) equilibrium with the medium), cubic boxes and closed-top conditions. Checks were performed on an unfractured porous medium and the convection cells do start for the theoretical value of Ra, namely 4p². 2D convection was verified up to Ra=800. The influence of parameters such as fracture aperture (or fracture transmissivity), fracture density and fracture length is studied. Moreover, these models are compared to porous media with the same macroscopic permeability. Preliminary results show that the non-uniqueness associated with initial conditions which makes possible either 2D or 3D convection in porous media (Schubert & Straus 1979) is no longer true for fractured porous media (at least for 50fracture density and fracture aperture on the Nusselt number (Nu) is highly Ra dependent. The effect of the damaged zone on Nu is roughly proportional to its size. All these models also allows us to determine for which range of fracture density the fractured porous medium is in good agreement with an unfractured porous medium of the same bulk permeability.

  13. Injection of radioactive waste by hydraulic fracturing at West Valley, New York. Volume 2. Text

    Energy Technology Data Exchange (ETDEWEB)

    1978-05-01

    Results of a preliminary study are presented of the technical feasibility of radioactive waste disposal by hydraulic fracturing and injection into shale formations below the Nuclear Fuel Services Incorporated site at West Valley, New York. At this time there are approximately 600,000 gallons of high level neutralized Purex waste, including both the supernate (liquid) and sludge, and a further 12,000 gallons of acidic Thorex waste stored in tanks at the West Valley facilities. This study assesses the possibility of combining these wastes in a suitable grout mixture and then injecting them into deep shale formations beneath the West Valley site as a means of permanent disposal. The preliminary feasibility assessment results indicated that at the 850 to 1,250 feet horizons, horizontal fracturing and injection could be effectively achieved. However, a detailed safety analysis is required to establish the acceptability of the degree of isolation. The principal concerns regarding isolation are due to existing and possible future water supply developments within the area and the local effects of the buried valley. In addition, possible future natural gas developments are of concern. The definition of an exclusion zone may be appropriate to avoid problems with these developments. The buried valley may require the injections to be limited to the lower horizon depending on the results of further investigations.

  14. Chest wall volume receiving >30 Gy predicts risk of severe pain and/or rib fracture after lung stereotactic body radiotherapy.

    Science.gov (United States)

    Dunlap, Neal E; Cai, Jing; Biedermann, Gregory B; Yang, Wensha; Benedict, Stanley H; Sheng, Ke; Schefter, Tracey E; Kavanagh, Brian D; Larner, James M

    2010-03-01

    To identify the dose-volume parameters that predict the risk of chest wall (CW) pain and/or rib fracture after lung stereotactic body radiotherapy. From a combined, larger multi-institution experience, 60 consecutive patients treated with three to five fractions of stereotactic body radiotherapy for primary or metastatic peripheral lung lesions were reviewed. CW pain was assessed using the Common Toxicity Criteria for pain. Peripheral lung lesions were defined as those located within 2.5 cm of the CW. A minimal point dose of 20 Gy to the CW was required. The CW volume receiving >or=20, >or=30, >or=40, >or=50, and >or=60 Gy was determined and related to the risk of CW toxicity. Of the 60 patients, 17 experienced Grade 3 CW pain and five rib fractures. The median interval to the onset of severe pain and/or fracture was 7.1 months. The risk of CW toxicity was fitted to the median effective concentration dose-response model. The CW volume receiving 30 Gy best predicted the risk of severe CW pain and/or rib fracture (R(2) = 0.9552). A volume threshold of 30 cm(3) was observed before severe pain and/or rib fracture was reported. A 30% risk of developing severe CW toxicity correlated with a CW volume of 35 cm(3) receiving 30 Gy. The development of CW toxicity is clinically relevant, and the CW should be considered an organ at risk in treatment planning. The CW volume receiving 30 Gy in three to five fractions should be limited to <30 cm(3), if possible, to reduce the risk of toxicity without compromising tumor coverage. Copyright (c) 2010 Elsevier Inc. All rights reserved.

  15. Lewis Structures Technology, 1988. Volume 3: Structural Integrity Fatigue and Fracture Wind Turbines HOST

    Science.gov (United States)

    1988-01-01

    The charter of the Structures Division is to perform and disseminate results of research conducted in support of aerospace engine structures. These results have a wide range of applicability to practioners of structural engineering mechanics beyond the aerospace arena. The specific purpose of the symposium was to familiarize the engineering structures community with the depth and range of research performed by the division and its academic and industrial partners. Sessions covered vibration control, fracture mechanics, ceramic component reliability, parallel computing, nondestructive evaluation, constitutive models and experimental capabilities, dynamic systems, fatigue and damage, wind turbines, hot section technology (HOST), aeroelasticity, structural mechanics codes, computational methods for dynamics, structural optimization, and applications of structural dynamics, and structural mechanics computer codes.

  16. Geothermal fracture stimulation technology. Volume II. High-temperature proppant testing

    Energy Technology Data Exchange (ETDEWEB)

    1980-07-01

    Data were obtained from a newly built proppant tester, operated at actual geothermal temperatures. The short term test results show that most proppants are temperature sensitive, particularly at the higher closure stresses. Many materials have been tested using a standard short-term test, i.e., fracture-free sand, bauxite, and a resin-coated sand retained good permeability at the high fluid temperatures in brine over a range of closure stresses. The tests were designed to simulate normal closure stress ranges for geothermal wells which are estimated to be from 2000 to 6000 psi. Although the ultra high closure stresses in oil and gas wells need not be considered with present geothermal resources, there is a definite need for chemically inert proppants that will retain high permeability for long time periods in the high temperature formations.

  17. Comparison between two pencil-type ionization chambers with sensitive volume length of 30 cm; Comparacao entre duas camaras de ionizacao do tipo lapis com comprimento de volume sensivel de 30 cm

    Energy Technology Data Exchange (ETDEWEB)

    Castro, Maysa C. de; Xavier, Marcos; Silva, Natalia F.; Caldas, Linda V.E., E-mail: mcastro@ipen.br, E-mail: mxavier@ipen.br, E-mail: nsilva@ipen.br, E-mail: lcaldas@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2016-07-01

    Computed tomography (CT) for imaging procedures has been growing due to advances in the equipment technology, providing a higher dose to the patient, in relation to other diagnostic radiology tests, resulting in a concern for the patients. The dosimetry in CT is carried out with a pencil-type ionization chamber with sensitive volume length of 10 cm. Studies have shown the underestimation of the dose values. In this work two ionization chambers with the sensitive volume length of 30 cm were developed. They were submitted to the main characterization tests; the results showed to be within the international recommended limits. (author)

  18. Hydrofracture Modeling Using Discrete Fracture Network in Barnett Shale

    Science.gov (United States)

    Yaghoubi, A.; Zoback, M. D.

    2012-12-01

    Shale gas has become an important source of unconventional reservoir in the united state over the past decade. Since the shale gas formations are impermeable, hydraulic fracturing from vertical and horizontal well are commonly approach to extract natural gas deposit from these unconventional sources. Hydraulic fracturing has been a successful and relatively inexpensive stimulation method for stimulation and enhances hydrocarbon recovery. Multistage hydro fracturing treatments in horizontal well creates a large stimulated reservoir volume. However, modeling hydraulic fracturing requires to prior knowledge of natural fracture network. This problem can be deal with Discrete Fracture network modeling. The objective of this study is first to model discrete fracture network and then simulate hydro-fracturing in five horizontal well of a case study in Barnett shale gas reservoir. In the case study, five horizontal wells have been drilled in Barnett shale gas reservoir in which each of them has 10 stages of hydro-fracturing stimulation. Of all five wells, just well C has a full comprehensive logging data. Fracture date detected using FMI image log of well C for building DFN model are associated with different sources of uncertainty; orientation, density and length. After building reservoir geomechanics model and detecting natural fracture form image log from well C, DFN model has built based on fracture parameters, orientation, intensity, shape size and permeability detected from image log and core data. Modeling hydrofractuing in five wells are consistent with critically stressed-fracture and micro-seismic events.

  19. Correlation of choroidal thickness and volume measurements with axial length and age using swept source optical coherence tomography and optical low-coherence reflectometry.

    Science.gov (United States)

    Michalewski, Janusz; Michalewska, Zofia; Nawrocka, Zofia; Bednarski, Maciej; Nawrocki, Jerzy

    2014-01-01

    To report choroidal thickness and volume in healthy eyes using swept source optical coherence tomography (SS-OCT). A prospective observational study of 122 patients examined with swept source OCT (DRI-OCT, Topcon, Japan). In each eye, we performed 256 horizontal scans, 12 mm in length and centered on the fovea. We calculated choroidal thickness manually with a built-in caliper and automatically using DRI-OCT mapping software. Choroidal volume was also automatically calculated. We measured axial length with optical low-coherence reflectometry (Lenstar LS 900, Haag-Streit, Switzerland). The choroid has focally increased thickness under the fovea. Choroid was thinnest in the outer nasal quadrant. In stepwise regression analysis, age was estimated as the most significant factor correlating with decreased choroidal thickness (F=23.146, Pchoroidal thickness and volume maps. Choroidal thickness is increased at the fovea and is thinnest nasally. Age and axial length are critical for the estimation of choroidal thickness and volume. Choroidal measurements derived from SS-OCT images have potential value for objectively documenting disease-related choroidal thickness abnormalities and monitoring progressive changes over time.

  20. Investigating Choroid Plexus Volume and Capillaries Length in 15.5 Day Foetus of Diabetic Mothers Compared to Normal Foetus in Rats

    Directory of Open Access Journals (Sweden)

    S Mohammadi

    2012-07-01

    Full Text Available Introduction: Diabetes mellitus is a metabolic disorder with systemic complications. Children of diabetic mothers are at risk of many disorders such as major and minor vascular injuries, retinopathy, and atherosclerosis. The present study aimed to investigate the effects of maternal diabetes on changes in choroid plexus volume and capillaries length in 15.5 day foetus. Methods: in this experimental study which was conducted on 30 male wistar rats, animals were divided into two groups; an experimental and a control group (n=10. Streptotosin was injected (55 mg/kg in experimental group to induce diabetes while in control group intra-peritoneal injection of buffer citrate was done for four weeks. In the last day of the fourth week, mating was done and zero day of pregnancy was determined with vaginal plug observation. on 15th day of pregnancy, rats were anatomized and a foetus was chosen from each mother. After foetal head fixation and tissue processing, serial horizontal sections were prepared and stained with haematoxylin-eosin. Choroid plexus volume was measured by stereological techniques and the results were analysed using ANOVA statistical test. Results: Results showed a significant difference between Choroid plexus volume and capillaries length in experimental and control groups, so that Choroid plexus volume and capillaries length were increased significantly in foetus of diabetic mothers(P<0.05. Conclusion: It is likely that maternal hyper-glycaemia induces a kind of angiogenesis in foetus that can cause many brain disorders.

  1. Correlation between the 2-Dimensional Extent of Orbital Defects and the 3-Dimensional Volume of Herniated Orbital Content in Patients with Isolated Orbital Wall Fractures

    Science.gov (United States)

    Cha, Jong Hyun; Moon, Myeong Ho; Lee, Yong Hae; Koh, In Chang; Kim, Kyu Nam; Kim, Chang Gyun

    2017-01-01

    Background The purpose of this study was to assess the correlation between the 2-dimensional (2D) extent of orbital defects and the 3-dimensional (3D) volume of herniated orbital content in patients with an orbital wall fracture. Methods This retrospective study was based on the medical records and radiologic data of 60 patients from January 2014 to June 2016 for a unilateral isolated orbital wall fracture. They were classified into 2 groups depending on whether the fracture involved the inferior wall (group I, n=30) or the medial wall (group M, n=30). The 2D area of the orbital defect was calculated using the conventional formula. The 2D extent of the orbital defect and the 3D volume of herniated orbital content were measured with 3D image processing software. Statistical analysis was performed to evaluate the correlations between the 2D and 3D parameters. Results Varying degrees of positive correlation were found between the 2D extent of the orbital defects and the 3D herniated orbital volume in both groups (Pearson correlation coefficient, 0.568−0.788; R2=32.2%−62.1%). Conclusions Both the calculated and measured 2D extent of the orbital defects showed a positive correlation with the 3D herniated orbital volume in orbital wall fractures. However, a relatively large volume of herniation (>0.9 cm3) occurred not infrequently despite the presence of a small orbital defect (<1.9 cm2). Therefore, estimating the 3D volume of the herniated content in addition to the 2D orbital defect would be helpful for determining whether surgery is indicated and ensuring adequate surgical outcomes. PMID:28194344

  2. Analysis of Orbital Volume Measurements Following Reduction and Internal Fixation Using Absorbable Mesh Plates and Screws for Patients With Orbital Floor Blowout Fractures.

    Science.gov (United States)

    Hwang, Won Joo; Lee, Do Heon; Choi, Won; Hwang, Jae Ha; Kim, Kwang Seog; Lee, Sam Yong

    2017-08-22

    Hinge-shaped fractures are common type of orbital floor blowout fractures, for which reduction and internal fixation is ideal. Nonetheless, orbital floor reconstruction using alloplastic materials without reducing the number of bone fragments is the most frequently used procedure. Therefore, this study analyzed and compared the outcomes between open reduction and internal fixation using absorbable mesh plates and screws, and orbital floor reconstruction, by measuring the orbital volume before and after surgery. Among patients with orbital floor blowout fractures, this study was conducted on 28 patients who underwent open reduction and internal fixation, and 27 patients who underwent orbital floor reconstruction from December 2008 to September 2015. The mechanism of injury, ophthalmic symptoms before and after surgery, and the degree of enophthalmos were examined; subsequently, the volumes of the affected and unaffected sides were measured before and after surgery based on computed tomography images. This study compared the degree of recovery in the correction rate of the orbital volume, ophthalmic symptoms, and enophthalmos between the 2 groups. The patients who underwent open reduction and internal fixation, and the patients who underwent orbital floor reconstruction showed average correction rates of 100.36% and 105.24%, respectively. Open reduction and internal fixation showed statistically, significantly superior treatment outcomes compared with orbital floor reconstruction. The ophthalmic symptoms and incidence of enophthalmos completely resolved in both groups. For orbital floor blowout fractures, open reduction and internal fixation using absorbable mesh plates and screws was a feasible alternative to orbital floor reconstruction.

  3. Gravity-Driven Hydraulic Fractures

    Science.gov (United States)

    Germanovich, L. N.; Garagash, D.; Murdoch, L. C.; Robinowitz, M.

    2014-12-01

    This study is motived by a new method for disposing of nuclear waste by injecting it as a dense slurry into a hydraulic fracture that grows downward to great enough depth to permanently isolate the waste. Disposing of nuclear waste using gravity-driven hydraulic fractures is mechanically similar to the upward growth of dikes filled with low density magma. A fundamental question in both applications is how the injected fluid controls the propagation dynamics and fracture geometry (depth and breadth) in three dimensions. Analog experiments in gelatin [e.g., Heimpel and Olson, 1994; Taisne and Tait, 2009] show that fracture breadth (the short horizontal dimension) remains nearly stationary when the process in the fracture "head" (where breadth is controlled) is dominated by solid toughness, whereas viscous fluid dissipation is dominant in the fracture tail. We model propagation of the resulting gravity-driven (buoyant or sinking), finger-like fracture of stationary breadth with slowly varying opening along the crack length. The elastic response to fluid loading in a horizontal cross-section is local and can be treated similar to the classical Perkins-Kern-Nordgren (PKN) model of hydraulic fracturing. The propagation condition for a finger-like crack is based on balancing the global energy release rate due to a unit crack extension with the rock fracture toughness. It allows us to relate the net fluid pressure at the tip to the fracture breadth and rock toughness. Unlike the PKN fracture, where breadth is known a priori, the final breadth of a finger-like fracture is a result of processes in the fracture head. Because the head is much more open than the tail, viscous pressure drop in the head can be neglected leading to a 3D analog of Weertman's hydrostatic pulse. This requires relaxing the local elasticity assumption of the PKN model in the fracture head. As a result, we resolve the breadth, and then match the viscosity-dominated tail with the 3-D, toughness

  4. 不同长度的玻璃纤维桩修复对下颌前磨牙抗折强度的影响%Effects of Fracture Resistance on Mandible Premolars Restored with Different Glass Fiber Post Lengths

    Institute of Scientific and Technical Information of China (English)

    李张维; 吴妹娟; 刘雪云; 潘宣; 李梁

    2011-01-01

    Objective To compare the influence of different glass - fiber post lengths on teeth fracture resistance.Metbods Thirty extracted human mandible premolars were endodontically treated after being cut off the crowns from the cemento - enamel junction.The teeth were randomly and equally divided into A, B,C groups which were post lengths of 5mm ( shorter than 1/1 clinical crown length) ,7mm ( 1/1 clinical crown length) , and 9mm ( longer than 1/1 clinical crown length) respectively.And then, all of them were restored with resin cores and metal crowns.All the teeth were fixed in a umversal text machine after embedded in acrylic resin blocks,which were tested for the fracture resistance,and recorded the counts and observed the fracture mode.Results Fracture resistance of group A of restoration was significantly lower than that of B group and C group (P <0.05).Fracture resistances of group B and C,however,were not s]gnificantly different ( P > 0.05 ) .Conclusion Glass fiber post lengths should not be shorter than clinical crowns when we use thcm to restore dcntal defects.%目的 比较玻璃纤维桩长度对牙齿抗折强度的影响.方法 选择30颗近期因正畸完整拔除的下颌前磨牙,自釉牙骨质界处截冠后行完善的根管治疗,随机分为A、B、C 3组,每组10颗.对应每组按5mm(短于修复体牙冠的长度),7mm(等于修复体牙冠的长度),9mm(大于修复体牙冠的长度)长度的纤维桩修复,树脂核加金属冠修复外形.自凝塑料包埋后,固定于万能试验机上测试实验牙的抗折强度,记录读数并观察修复体折裂模式.结果 A组的修复体抗折强度低于B组与C组(P0.05).结论 使用玻璃纤维桩修复缺损牙体时,桩的长度不应短于临床牙冠的长度.

  5. Analysis of the structural parameters that influence gas production from the Devonian shale. Annual progress report, 1979-1980. Volume II. Data repository and reports published during fiscal year 1979-1980: regional structure, surface structure, surface fractures, hydrology

    Energy Technology Data Exchange (ETDEWEB)

    Negus-De Wys, J.; Dixon, J. M.; Evans, M. A.; Lee, K. D.; Ruotsala, J. E.; Wilson, T. H.; Williams, R. T.

    1980-10-01

    This volume comprises appendices giving regional structure data, surface structure data, surface fracture data, and hydrology data. The fracture data covers oriented Devonian shale cores from West Virginia, Ohio, Virginia, Pennsylvania, and Kentucky. The subsurface structure of the Eastern Kentucky gas field is also covered. (DLC)

  6. Evaluating the effect of internal aperture variability on transport in kilometer scale discrete fracture networks

    Science.gov (United States)

    Makedonska, Nataliia; Hyman, Jeffrey D.; Karra, Satish; Painter, Scott L.; Gable, Carl W.; Viswanathan, Hari S.

    2016-08-01

    The apertures of natural fractures in fractured rock are highly heterogeneous. However, in-fracture aperture variability is often neglected in flow and transport modeling and individual fractures are assumed to have uniform aperture distribution. The relative importance of in-fracture variability in flow and transport modeling within kilometer-scale field-scale fracture networks has been under a matter of debate for a long time because the flow in each single fracture is controlled not only by in-fracture variability but also by boundary conditions. Computational limitations have previously prohibited researchers from investigating the relative importance of in-fracture variability in flow and transport modeling within large-scale fracture networks. We address this question by incorporating internal heterogeneity of individual fractures into flow simulations within kilometer scale three-dimensional fracture networks, where fracture intensity, P32 (ratio between total fracture area and domain volume) is between 0.027 and 0.031 [1/m]. A recently developed discrete fracture network (DFN) simulation capability, dfnWorks, is used to generate DFNs that include in-fracture aperture variability represented by a stationary log-normal stochastic field with various correlation lengths and variances. The Lagrangian transport parameters, non-reacting travel time and cumulative retention, are calculated along particles streamlines. It is observed that due to local flow channeling early particle travel times are more sensitive to in-fracture variability than the tails of travel time distributions, where no significant effect of the in-fracture transmissivity variations and spatial correlation length is observed.

  7. Data regarding hydraulic fracturing distributions and treatment fluids, additives, proppants, and water volumes applied to wells drilled in the United States from 1947 through 2010

    Science.gov (United States)

    Gallegos, Tanya J.; Varela, Brian A.

    2015-01-01

    Comprehensive, published, and publicly available data regarding the extent, location, and character of hydraulic fracturing in the United States are scarce. The objective of this data series is to publish data related to hydraulic fracturing in the public domain. The spreadsheets released with this data series contain derivative datasets aggregated temporally and spatially from the commercial and proprietary IHS database of U.S. oil and gas production and well data (IHS Energy, 2011). These datasets, served in 21 spreadsheets in Microsoft Excel (.xlsx) format, outline the geographical distributions of hydraulic fracturing treatments and associated wells (including well drill-hole directions) as well as water volumes, proppants, treatment fluids, and additives used in hydraulic fracturing treatments in the United States from 1947 through 2010. This report also describes the data—extraction/aggregation processing steps, field names and descriptions, field types and sources. An associated scientific investigation report (Gallegos and Varela, 2014) provides a detailed analysis of the data presented in this data series and comparisons of the data and trends to the literature.

  8. Federal Logistics Information Systems. FLIS Procedures Manual. Document Identifier Code Input/Output Formats (Variable Length). Volume 9.

    Science.gov (United States)

    2007-11-02

    49017-3084 CH I CHANGE NO. 1 DoD 4100.39-M DoD 4100.39-M Volume 9 V DLSC- VPH 1 July 1997 _-’ FEDERAL LOGISTICS INFORMATION SYSTEM (FLIS) PROCEDURES...47 3053 UNIT OF ISSUE CONVERSION FACTOR 0005N H 02 QS 8472 FORMER UNIT OF ISSUE 0002A H 89 0211 OCCURS COUNTER/li/ 0001N H GV 2862 PHRASE CODE...16 0707 MANAGEMENT CONTROL DATA, COAST GUARD 0007X H 16 0443 EXPANSION FIELD 1 0001X H 47 3053 UNIT OF ISSUE CONVERSION FACTOR 0005N H 02 0S 8472

  9. Triaxial coreflood study of the hydraulic fracturing of Utica Shale

    Science.gov (United States)

    Carey, J. W.; Frash, L.; Viswanathan, H. S.

    2015-12-01

    One of the central questions in unconventional oil and gas production research is the cause of limited recovery of hydrocarbon. There are many hypotheses including: 1) inadequate penetration of fractures within the stimulated volume; 2) limited proppant delivery; 3) multiphase flow phenomena that blocks hydrocarbon migration; etc. Underlying any solution to this problem must be an understanding of the hydrologic properties of hydraulically fractured shale. In this study, we conduct triaxial coreflood experiments using a gasket sealing mechanism to characterize hydraulic fracture development and permeability of Utica Shale samples. Our approach also includes fracture propagation with proppants. The triaxial coreflood experiments were conducted with an integrated x-ray tomography system that allows direct observation of fracture development using x-ray video radiography and x-ray computed tomography at elevated pressure. A semi-circular, fracture initiation notch was cut into an end-face of the cylindrical samples (1"-diameter with lengths from 0.375 to 1"). The notch was aligned parallel with the x-ray beam to allow video radiography of fracture growth as a function of injection pressure. The proppants included tungsten powder that provided good x-ray contrast for tracing proppant delivery and distribution within the fracture system. Fractures were propagated at injection pressures in excess of the confining pressure and permeability measurements were made in samples where the fractures propagated through the length of the sample, ideally without penetrating the sample sides. Following fracture development, permeability was characterized as a function of hydrostatic pressure and injection pressure. X-ray video radioadiography was used to study changes in fracture aperture in relation to permeability and proppant embedment. X-ray tomography was collected at steady-state conditions to fully characterize fracture geometry and proppant distribution.

  10. Fluid driven fracture mechanics in highly anisotropic shale: a laboratory study with application to hydraulic fracturing

    Science.gov (United States)

    Gehne, Stephan; Benson, Philip; Koor, Nick; Enfield, Mark

    2017-04-01

    The finding of considerable volumes of hydrocarbon resources within tight sedimentary rock formations in the UK led to focused attention on the fundamental fracture properties of low permeability rock types and hydraulic fracturing. Despite much research in these fields, there remains a scarcity of available experimental data concerning the fracture mechanics of fluid driven fracturing and the fracture properties of anisotropic, low permeability rock types. In this study, hydraulic fracturing is simulated in a controlled laboratory environment to track fracture nucleation (location) and propagation (velocity) in space and time and assess how environmental factors and rock properties influence the fracture process and the developing fracture network. Here we report data on employing fluid overpressure to generate a permeable network of micro tensile fractures in a highly anisotropic shale ( 50% P-wave velocity anisotropy). Experiments are carried out in a triaxial deformation apparatus using cylindrical samples. The bedding planes are orientated either parallel or normal to the major principal stress direction (σ1). A newly developed technique, using a steel guide arrangement to direct pressurised fluid into a sealed section of an axially drilled conduit, allows the pore fluid to contact the rock directly and to initiate tensile fractures from the pre-defined zone inside the sample. Acoustic Emission location is used to record and map the nucleation and development of the micro-fracture network. Indirect tensile strength measurements at atmospheric pressure show a high tensile strength anisotropy ( 60%) of the shale. Depending on the relative bedding orientation within the stress field, we find that fluid induced fractures in the sample propagate in two of the three principal fracture orientations: Divider and Short-Transverse. The fracture progresses parallel to the bedding plane (Short-Transverse orientation) if the bedding plane is aligned (parallel) with the

  11. Diffusion effects on volume-selective NMR at small length scales; Diffusionseffekte in volumenselektiver NMR auf kleinen Laengenskalen

    Energy Technology Data Exchange (ETDEWEB)

    Gaedke, Achim

    2009-01-21

    In this thesis, the interplay between diffusion and relaxation effects in spatially selective NMR experiments at short length scales is explored. This is especially relevant in the context of both conventional and mechanically detected MRI at (sub)micron resolution in biological specimens. Recent results on selectively excited very thin slices showed an in-slice-magnetization recovery orders of magnitude faster than the longitudinal relaxation time T1. However, those experiments were run on fully relaxed samples while MRI and especially mechanically detected NMR experiments are typically run in a periodic fashion with repetition times far below T1. The main purpose of this work therefore was to extend the study of the interplay between diffusion and longitudinal relaxation to periodic excitations. In some way, this is inverse phenomenon to the DESIRE (Diffusive Enhancement of SIgnal and REsolution) approach, proposed 1992 by Lauterbur. Experiments on periodically excited thin slices were carried out at a dedicated static field gradient cryomagnet with magnetic field gradients up to 180 T/m. In order to obtain plane slices, an appropriate isosurface of the gradient magnet had to be identified. It was found at a field of 3.8 T with a gradient of 73 T/m. In this field, slices down to a thickness of 3.2 {mu}m could be excited. The detection of the NMR signal was done using FIDs instead of echoes as the excitation bandwidth of those thin slices is sufficiently small to observe FIDs which are usually considered to be elusive to detection in such strong static field gradients. A simulation toolbox based on the full Bloch-Torrey-equation was developed to describe the excitation and the formation of NMR signals under those unusual conditions as well as the interplay of diffusion and magnetization recovery. Both the experiments and the simulations indicate that diffusion effects lead to a strongly enhanced magnetization modulation signal also under periodic excitation

  12. Dynamics of volume of competition practice and facilities of training of jumpers in length and triple in the process of long-term preparation

    Directory of Open Access Journals (Sweden)

    Sovenko S.P.

    2012-12-01

    Full Text Available Analysed and systematized information in relation to the volume of competition practice and facilities of different primary orientation of jumpers in length and triple in the process of long-term preparation. The expert questioning is conducted 16 trainers. The documents of planning of training process are analysed, the analysis of diaries of sportsmen is carried out (n=22. The volume of competition practice of sportsmen and facilities of training of different primary orientation is certain. The results of analysis in relation to the construction of training process are reflected by the leading trainers of Ukraine on track-and-field. An approach classification of facilities of training taking into account the specific of training process of sportsmen is presented. It is set that the volume of facilities of general preparation is most on the initial stages of long-term perfection, then stabilized on the stages specialized base and preparations to higher achievements and a few diminishes on maximal implementation of individual possibilities and maintainance of higher sporting trade phases. It is related to diminishing of duration of the general preparatory stages of annual preparation.

  13. Reanalysis of multi-temporal aerial images of Storglaciären, Sweden (1959–99 – Part 1: Determination of length, area, and volume changes

    Directory of Open Access Journals (Sweden)

    W. Haeberli

    2010-09-01

    Full Text Available Storglaciären, located in the Kebnekaise massif in northern Sweden, has a long history of glaciological research. Early photo documentations date back to the late 19th century. Measurements of front position variations and distributed mass balance have been carried out since 1910 and 1945/46, respectively. In addition to these in-situ measurements, aerial photographs have been taken at decadal intervals since the beginning of the mass balance monitoring program and were used to produce topographic glacier maps. Inaccuracies in the maps were a challenge to early attempts to derive glacier volume changes and resulted in major differences when compared to the direct glaciological mass balances. In this study, we reanalyzed dia-positives of the original aerial photographs of 1959, -69, -80, -90 and -99 based on consistent photogrammetric processing. From the resulting digital elevation models and orthophotos, changes in length, area, and volume of Storglaciären were computed between the survey years, including an assessment of related errors. Between 1959 and 1999, Storglaciären lost an ice volume of 19×106 m3, which corresponds to a cumulative ice thickness loss of 5.69 m and a mean annual loss of 0.14 m. This ice loss resulted largely from a strong volume loss during the period 1959–80 and was partly compensated during the period 1980–99. As a consequence, the glacier shows a strong retreat in the 1960s, a slowing in the 1970s, and pseudo-stationary conditions in the 1980s and 1990s.

  14. Estimation of regional myocardial mass at risk based on distal arterial lumen volume and length using 3D micro-CT images.

    Science.gov (United States)

    Le, Huy; Wong, Jerry T; Molloi, Sabee

    2008-09-01

    The determination of regional myocardial mass at risk distal to a coronary occlusion provides valuable prognostic information for a patient with coronary artery disease. The coronary arterial system follows a design rule which allows for the use of arterial branch length and lumen volume to estimate regional myocardial mass at risk. Image processing techniques, such as segmentation, skeletonization and arterial network tracking, are presented for extracting anatomical details of the coronary arterial system using micro-computed tomography (micro-CT). Moreover, a method of assigning tissue voxels to their corresponding arterial branches is presented to determine the dependent myocardial region. The proposed micro-CT technique was utilized to investigate the relationship between the sum of the distal coronary arterial branch lengths and volumes to the dependent regional myocardial mass using a polymer cast of a porcine heart. The correlations of the logarithm of the total distal arterial lengths (L) to the logarithm of the regional myocardial mass (M) for the left anterior descending (LAD), left circumflex (LCX) and right coronary (RCA) arteries were log(L)=0.73log(M)+0.09 (R=0.78), log(L)=0.82log(M)+0.05 (R=0.77) and log(L)=0.85log(M)+0.05 (R=0.87), respectively. The correlation of the logarithm of the total distal arterial lumen volumes (V) to the logarithm of the regional myocardial mass for the LAD, LCX and RCA were log(V)=0.93log(M)-1.65 (R=0.81), log(V)=1.02log(M)-1.79 (R=0.78) and log(V)=1.17log(M)-2.10 (R=0.82), respectively. These morphological relations did not change appreciably for diameter truncations of 600-1400microm. The results indicate that the image processing procedures successfully extracted information from a large 3D dataset of the coronary arterial tree to provide prognostic indications in the form of arterial tree parameters and anatomical area at risk.

  15. Potential Impacts of Spilled Hydraulic Fracturing Fluid Chemicals on Water Resources: Types, volumes, and physical-chemical properties of chemicals

    Science.gov (United States)

    Hydraulic fracturing (HF) fluid chemicals spilled on-site may impact drinking water resources. While chemicals generally make up <2% of the total injected fluid composition by mass, spills may have undiluted concentrations. HF fluids typically consist of a mixture of base flui...

  16. Note: fast and reliable fracture strain extraction technique applied to silicon at nanometer scale.

    Science.gov (United States)

    Passi, Vikram; Bhaskar, Umesh; Pardoen, Thomas; Sodervall, Ulf; Nilsson, Bengt; Petersson, Goran; Hagberg, Mats; Raskin, Jean-Pierre

    2011-11-01

    Simple fabrication process and extraction procedure to determine the fracture strain of monocrystalline silicon are demonstrated. Nanowires/nanoribbons in silicon are fabricated and subjected to uniaxial tensile stress along the complete length of the beams. Large strains up to 5% are measured for nanowires presenting a cross section of 50 nm × 50 nm and a length of 2.5 μm. An increase in fracture strain for silicon nanowires (NWs) with the downscaling of their volume is observed, highlighting the reduction of the defects probability as volume is decreased.

  17. Mode I fracture of sheet metal

    Science.gov (United States)

    Pardoen, T.; Hachez, F.; Marchioni, B.; Blyth, P. H.; Atkins, A. G.

    2004-02-01

    The perceived wisdom about thin sheet fracture is that (i) the crack propagates under mixed mode I & III giving rise to a slant through-thickness fracture profile and (ii) the fracture toughness remains constant at low thickness and eventually decreases with increasing thickness. In the present study, fracture tests performed on thin DENT plates of various thicknesses made of stainless steel, mild steel, 6082-O and NS4 aluminium alloys, brass, bronze, lead, and zinc systematically exhibit (i) mode I "bath-tub", i.e. "cup & cup", fracture profiles with limited shear lips and significant localized necking (more than 50% thickness reduction), (ii) a fracture toughness that linearly increases with increasing thickness (in the range of 0.5- 5 mm). The different contributions to the work expended during fracture of these materials are separated based on dimensional considerations. The paper emphasises the two parts of the work spent in the fracture process zone: the necking work and the "fracture" work. Experiments show that, as expected, the work of necking per unit area linearly increases with thickness. For a typical thickness of 1 mm, both fracture and necking contributions have the same order of magnitude in most of the metals investigated. A model is developed in order to independently evaluate the work of necking, which successfully predicts the experimental values. Furthermore, it enables the fracture energy to be derived from tests performed with only one specimen thickness. In a second modelling step, the work of fracture is computed using an enhanced void growth model valid in the quasi plane stress regime. The fracture energy varies linearly with the yield stress and void spacing and is a strong function of the hardening exponent and initial void volume fraction. The coupling of the two models allows the relative contributions of necking versus fracture to be quantified with respect to (i) the two length scales involved in this problem, i.e. the void spacing

  18. Sodium metabisulphite, a preservative agent, decreases the heart capillary volume and length, and curcumin, the main component of Curcuma longa, cannot protect it.

    Science.gov (United States)

    Noorafshan, A; Asadi-Golshan, R; Monjezi, S; Karbalay-Doust, S

    2014-01-01

    Sodium metabisulphite is used as an antioxidant agent in many pharmaceutical formulations. It is extensively used as a food preservative and disinfectant. It has been demonstrated that sulphite exposure can affect some organs. Curcumin, the main element of Curcuma longa, has been identified to have multiple protective properties. The present study extends the earlier works to quantitative evaluation of the effects of sulphite and curcumin on the heart structure using stereological methods. In this study, 28 rats were randomly divided into four experimental groups. The rats in groups I to IV received distilled water (group I), sodium metabisulphite (25 mg/ kg/day) (group II), curcumin (100 mg/kg/day) (group III), and sodium metabisulphite+curcumin (group IV), respectively, for 8 weeks. The left ventricle was subjected to stereological methods to estimate the quantitative parameters of the myocardium. A 20 % decrease was observed in the total volume of ventricular tissue in the sulphite-treated animals compared to the distilled water treatment (P preservative food agent, reduced the length and volume of the ventricular capillaries and curcumin could not protect them.

  19. The relationship between the size of traumatic epidural hematoma and the length,type and location of fracture line%外伤性硬膜外血肿大小与骨折线长度、类型及部位的关系

    Institute of Scientific and Technical Information of China (English)

    李振; 侯黎明; 何彦雨; 裴玉春; 汪棋生; 唐清明

    2014-01-01

    Objective To investigate the relationship between the size of traumatic epidural hematoma (TEDH) and the length ,type and location of fracture line. Methods The data of 173 patients with TEDH in our hospital from June 2010 to May 2013 were collected including demographics ,clinical manifestations ,CT and other ancillary test results. The patients with TEDH were divided into the group H (n=95 ,> 15 mL) and group L (n=78 ,<15 mL) according to the hematoma size. The fracture line length ,hematoma volume and bleeding site were measured by CT and (or CTA). Results Group H had more comminuted fracturesmore and less linear fracture compared with group L ,which had significant difference. The fracture line length in group H was longer than that in group L in patients with linear fracture. Moreover ,the linear fracture was more com-mon than comminuted fracturesmore in occiput of patients with TEDH. Conclusion Hematoma volume of patients with TEDH has the certain relationship with the fracture type and fracture line length.%目的:通过观察外伤性硬膜外血肿患者的CT特点,探讨硬膜外血肿大小与骨折线长度、类型及部位的关系,为临床观察病情和手术止血提供依据。方法2010-06-2013-05在我院神经外科连续入院的外伤性硬膜外血肿患者。收集包括人口学因素、临床表现、CT及其他辅助检查结果等数据。根据血肿大小将研究对象分为H组(>15mL)和L组(<15mL)。以冠状缝、人字缝、颞骨鳞状缝将脑颅分为额部、顶部、枕部、颞部4个区域,如血肿跨区域的则以主要部分分类。通过CT和(或CTA)测量骨折线长度和血肿量、出血部位。结果共纳入173例,其中H组患者95例(54.9%)。左侧H组比例明显低于L组(22%vs27.7%,P<0.05),而右侧H组的比例高于L组(34.1%vs19.7%,P<0.05)。与L组相比,H组中粉碎性骨折较常见(26%vs10.4%,P<0.05),但线性骨折比例

  20. Trends in hydraulic fracturing distributions and treatment fluids, additives, proppants, and water volumes applied to wells drilled in the United States from 1947 through 2010: data analysis and comparison to the literature

    Science.gov (United States)

    Gallegos, Tanya J.; Varela, Brian A.

    2015-01-01

    Hydraulic fracturing is presently the primary stimulation technique for oil and gas production in low-permeability, unconventional reservoirs. Comprehensive, published, and publicly available information regarding the extent, location, and character of hydraulic fracturing in the United States is scarce. This national spatial and temporal analysis of data on nearly 1 million hydraulically fractured wells and 1.8 million fracturing treatment records from 1947 through 2010 (aggregated in Data Series 868) is used to identify hydraulic fracturing trends in drilling methods and use of proppants, treatment fluids, additives, and water in the United States. These trends are compared to the literature in an effort to establish a common understanding of the differences in drilling methods, treatment fluids, and chemical additives and of how the newer technology has affected the water use volumes and areal distribution of hydraulic fracturing. Historically, Texas has had the highest number of records of hydraulic fracturing treatments and associated wells in the United States documented in the datasets described herein. Water-intensive horizontal/directional drilling has also increased from 6 percent of new hydraulically fractured wells drilled in the United States in 2000 to 42 percent of new wells drilled in 2010. Increases in horizontal drilling also coincided with the emergence of water-based “slick water” fracturing fluids. As such, the most current hydraulic fracturing materials and methods are notably different from those used in previous decades and have contributed to the development of previously inaccessible unconventional oil and gas production target areas, namely in shale and tight-sand reservoirs. Publicly available derivative datasets and locations developed from these analyses are described.

  1. 玻璃纤维桩长度和纤维含量对牙体抗折强度的影响%Effects of Fiber Length and Content of Glass Fiber Posts on the Fracture Resistance of Teeth

    Institute of Scientific and Technical Information of China (English)

    孙宁宁; 殷恺; 李玉民

    2014-01-01

    Objective To explore the influence of different lengths and contents of glass-fiber post on the fracture resistance of teeth, and to investigate the optimal length and content of glass-fiber post used for restorative treatment. Meth-ods Forty-two intact single canal mandibular premolars were collected from orthodontic patients and were divided into three experimental groups (A, B and C). All the teeth were endodontically treated after cut off the crowns from the 2 mm above cemento-enamel junction. The post lengths were10 mm in A group, 8 mm in B group, and 6 mm in C group.There were two subgroups for each experimental group (A1, A2, B1, B2, C1, C2 ), 7 teeth for each subgroup.The 42%glass fiber post was used in A1, B1 and C1 groups. The 75%glass fiber post was used in A2, B2 and C2 groups. All of groups were restored with resin cores and metal crowns. The fracture resistance was measured with universal testing machine and recorded the root frac-ture pressure data and the mode of all the teeth. Results The fracture resistance was significantly higher in group A than that of group B and group C (P<0.05), and the fracture resistance was significantly higher in group B than that of group C (P<0.05). The fracture resistance was significantly higher for 75%glass fiber post than that of 42%glass fiber post (P<0.05). Conclusion Within a certain range, the longer the length of glass fiber post, the greater the tooth fracture resistance. The fracture resistance of fiber content is better for 75%glass fiber post than that of 42%glass fiber post.%目的:研究玻璃纤维桩长度和纤维含量对牙齿抗折强度的影响,探索进行牙体缺损修复所适宜的玻璃纤维桩长度和纤维含量。方法选择42颗因正畸拔除完整的下颌前磨牙,随机分为A、B、C3个实验组,每组14颗牙。自釉牙骨质界上2 mm截冠后行完善的根管治疗,进行桩道预备,桩道深度分别为A组10 mm、B组8 mm、C组6 mm

  2. Optimizing for Large Planar Fractures in Multistage Horizontal Wells in Enhanced Geothermal Systems Using a Coupled Fluid and Geomechanics Simulator

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Xiexiaomen; Tutuncu, Azra; Eustes, Alfred; Augustine, Chad

    2017-05-01

    Enhanced Geothermal Systems (EGS) could potentially use technological advancements in coupled implementation of horizontal drilling and multistage hydraulic fracturing techniques in tight oil and shale gas reservoirs along with improvements in reservoir simulation techniques to design and create EGS reservoirs. In this study, a commercial hydraulic fracture simulation package, Mangrove by Schlumberger, was used in an EGS model with largely distributed pre-existing natural fractures to model fracture propagation during the creation of a complex fracture network. The main goal of this study is to investigate optimum treatment parameters in creating multiple large, planar fractures to hydraulically connect a horizontal injection well and a horizontal production well that are 10,000 ft. deep and spaced 500 ft. apart from each other. A matrix of simulations for this study was carried out to determine the influence of reservoir and treatment parameters on preventing (or aiding) the creation of large planar fractures. The reservoir parameters investigated during the matrix simulations include the in-situ stress state and properties of the natural fracture set such as the primary and secondary fracture orientation, average fracture length, and average fracture spacing. The treatment parameters investigated during the simulations were fluid viscosity, proppant concentration, pump rate, and pump volume. A final simulation with optimized design parameters was performed. The optimized design simulation indicated that high fluid viscosity, high proppant concentration, large pump volume and pump rate tend to minimize the complexity of the created fracture network. Additionally, a reservoir with 'friendly' formation characteristics such as large stress anisotropy, natural fractures set parallel to the maximum horizontal principal stress (SHmax), and large natural fracture spacing also promote the creation of large planar fractures while minimizing fracture complexity.

  3. The Benefits of Maximum Likelihood Estimators in Predicting Bulk Permeability and Upscaling Fracture Networks

    Science.gov (United States)

    Emanuele Rizzo, Roberto; Healy, David; De Siena, Luca

    2016-04-01

    The success of any predictive model is largely dependent on the accuracy with which its parameters are known. When characterising fracture networks in fractured rock, one of the main issues is accurately scaling the parameters governing the distribution of fracture attributes. Optimal characterisation and analysis of fracture attributes (lengths, apertures, orientations and densities) is fundamental to the estimation of permeability and fluid flow, which are of primary importance in a number of contexts including: hydrocarbon production from fractured reservoirs; geothermal energy extraction; and deeper Earth systems, such as earthquakes and ocean floor hydrothermal venting. Our work links outcrop fracture data to modelled fracture networks in order to numerically predict bulk permeability. We collected outcrop data from a highly fractured upper Miocene biosiliceous mudstone formation, cropping out along the coastline north of Santa Cruz (California, USA). Using outcrop fracture networks as analogues for subsurface fracture systems has several advantages, because key fracture attributes such as spatial arrangements and lengths can be effectively measured only on outcrops [1]. However, a limitation when dealing with outcrop data is the relative sparseness of natural data due to the intrinsic finite size of the outcrops. We make use of a statistical approach for the overall workflow, starting from data collection with the Circular Windows Method [2]. Then we analyse the data statistically using Maximum Likelihood Estimators, which provide greater accuracy compared to the more commonly used Least Squares linear regression when investigating distribution of fracture attributes. Finally, we estimate the bulk permeability of the fractured rock mass using Oda's tensorial approach [3]. The higher quality of this statistical analysis is fundamental: better statistics of the fracture attributes means more accurate permeability estimation, since the fracture attributes feed

  4. Damage Tolerant Design Handbook. A Compilation of Fracture and Crack- Growth Data for High-Strength Alloys. Volume 4

    Science.gov (United States)

    1983-12-01

    rIJfrd rd LLJ 0 n I lM ~ m ~m m r)Mm ul M n C) tm M1,N , , Il rl N t, P N rN N N 1l- 1 z 0 Z Z 1, I . N. A N) 3 v1 0 td ly I 0Mn a), M 00-ra N r-i...v- 0uA w . w ! I zI ) l0 r I P, 1 0 0 0 t 0 1 0 0 -w i a. - 0 - -0 0 0-. 0 0 in0 I A C d ~C C rd rd I M td 444 rd 4 4 0 0 0000 0 00 NW C) C, M) U rd...ORIENTATION:T-L CRACK LENGTH (A0): YIELD STRENGTH: K iscc: ULT. STRENGTH: REFERENCES:85543 77 K max (MPA Vmh K max (MPA V/’m 4 10 40 104 10 40 100

  5. Numerical investigation and optimization of multiple fractures in tight gas reservoirs

    Energy Technology Data Exchange (ETDEWEB)

    Hou, M.Z. [Technische Univ. Clausthal, Clausthal-Zellerfeld (Germany). ITE; Energie-Forschungszentrum Niedersachsen, Goslar (Germany); Zhou, L. [Energie-Forschungszentrum Niedersachsen, Goslar (Germany)

    2013-08-01

    The main objective of the project DGMK-680 in phase 2 was to investigate the influence of fractures on each other in a multi-fracture system including their space optimization by using the numerical program FLAC3D with our own developments, which treats all fractures in one 3D geometric model under 3D stress state with fully hydro-mechanical coupling effect. The case study was conducted on a horizontal wellbore at location A, which was stimulated hydraulically with a total of eight transverse fractures in summer 2009. Transverse multiple fractures were simulated using the modified continuum method. In the simulation all fractures were generated in one single model, comprising 22 different rock layers. Each layer was assumed to be homogeneous with regard to its rock and hydromechanical parameters. Thus the influence of the individual fractures on each other can be investigated. The simulation procedure applied, which is a consecutive execution ofa hydraulic and a mechanical computation, is the same for all fractures. The only differences are the primary in-situ stresses, the initial pore pressure, the injection parameters (location, rate, volume, duration), which lead to different patterns of fracture propagations. But there are still some common points, such as irregular patterns of the fracture front, which represents the heterogeneity of the model. All fractures (1 to 8) have their fracture average half-length between 70 m to 115 m, height between 93 m to 114 m and average width between 18 mm to 31 mm. The percentage difference of fracture height for individual fractures is obviously smaller than that of the fracture half-lengths, because the fracture barriers at bottom and top limit the fracture propagation in z-direction. Incomparison with the analytical simulator (FracPro) most results match well. Simulation of multiple fractures at location A, with the newly developed algorithms, shows that individual transverse multiple fractures at distances between 100

  6. Chopart fractures.

    Science.gov (United States)

    Klaue, Kaj

    2004-09-01

    The Chopart articular space was described by François Chopart (1743-1795) as a practical space for amputations in cases of distal foot necrosis. It corresponds to the limit between the anatomical hind-foot and the mid-foot. The bones involved are the talus and the calcaneus proximally, and the navicular and the cuboid distally. This space thus holds two functionally distinct entities, the anterior part of the coxa pedis (an essential functional joint) and the calcaneo-cuboidal joint,which can be considered to be an "adaptive joint" within a normal foot. Trauma to this region may cause fractures and/or dislocations and, in high energy trauma,compartment syndromes. Principles of treatment are immediate reduction of dislocations and realignment of the medial and lateral column of the foot in length and orientation. Open reduction and internal fixation of talus and navicular fractures are often indicated to restore the "coxa pedis". Open reconstruction or fusion in correct length of the calcaneo-cuboidal joint is occasionally indicated. Salvage procedures in malunions include navicular osteotomies and calcaneo-cuboidal bone block fusions. Treatment of joint destructions, especially involving the talo-navicular joint, include triple arthrodesis.

  7. Fracture and ductile vs. brittle behavior -- Theory, modeling and experiment

    Energy Technology Data Exchange (ETDEWEB)

    Beltz, G.E. [ed.] [Univ. of California, Santa Barbara, CA (United States); Selinger, R.L.B. [ed.] [Catholic Univ., Washington, DC (United States); Kim, K.S. [ed.] [Brown Univ., Providence, RI (United States); Marder, M.P. [ed.] [Univ. of Texas, Austin, TX (United States)

    1999-08-01

    The symposium brought together the many communities that investigate the fundamentals of fracture, with special emphasis on the ductile/brittle transition across a broad spectrum of material classes, fracture at interfaces, and modelling fracture over various length scales. Theoretical techniques discussed ranged from first-principles electronic structure theory to atomistic simulation to mesoscale and continuum theories, along with studies of fractals and scaling in fracture. Experimental and theoretical talks were interspersed throughout all sessions, rather than being segregated. The contributions to this volume generally follow the topical outline upon which the symposium was organized. The first part, dealing with ductile vs. brittle behavior in metals, concerns itself with investigations of high-strength steel, magnesium alloys, ordered intermetallics, and Fe-Cr-Al alloys. The development of analytical methods based on micromechanical models, such as dislocation mechanics and cohesive/contact zone models, are covered in a follow-up section. Nonmetals, including silicon, are considered in Parts 3 and 4. Fractals, chaos, and scaling theories are taken up in Part 5, with a special emphasis on fracture in heterogeneous solids. Modelling based on large populations of dislocations has substantially progressed during the past three years; hence, a section devoted to crystal plasticity and mesoscale dislocation modelling appears next. Finally, the technologically significant area of interfacial fracture, with applications to composites and intergranular fracture, is taken up in Part 7. Separate abstracts were prepared for most of the papers in this book.

  8. Fracture Propagation, Fluid Flow, and Geomechanics of Water-Based Hydraulic Fracturing in Shale Gas Systems and Electromagnetic Geophysical Monitoring of Fluid Migration

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jihoon; Um, Evan; Moridis, George

    2014-12-01

    We investigate fracture propagation induced by hydraulic fracturing with water injection, using numerical simulation. For rigorous, full 3D modeling, we employ a numerical method that can model failure resulting from tensile and shear stresses, dynamic nonlinear permeability, leak-off in all directions, and thermo-poro-mechanical effects with the double porosity approach. Our numerical results indicate that fracture propagation is not the same as propagation of the water front, because fracturing is governed by geomechanics, whereas water saturation is determined by fluid flow. At early times, the water saturation front is almost identical to the fracture tip, suggesting that the fracture is mostly filled with injected water. However, at late times, advance of the water front is retarded compared to fracture propagation, yielding a significant gap between the water front and the fracture top, which is filled with reservoir gas. We also find considerable leak-off of water to the reservoir. The inconsistency between the fracture volume and the volume of injected water cannot properly calculate the fracture length, when it is estimated based on the simple assumption that the fracture is fully saturated with injected water. As an example of flow-geomechanical responses, we identify pressure fluctuation under constant water injection, because hydraulic fracturing is itself a set of many failure processes, in which pressure consistently drops when failure occurs, but fluctuation decreases as the fracture length grows. We also study application of electromagnetic (EM) geophysical methods, because these methods are highly sensitive to changes in porosity and pore-fluid properties due to water injection into gas reservoirs. Employing a 3D finite-element EM geophysical simulator, we evaluate the sensitivity of the crosswell EM method for monitoring fluid movements in shaly reservoirs. For this sensitivity evaluation, reservoir models are generated through the coupled flow

  9. Myofilament length dependent activation

    Energy Technology Data Exchange (ETDEWEB)

    de Tombe, Pieter P.; Mateja, Ryan D.; Tachampa, Kittipong; Mou, Younss Ait; Farman, Gerrie P.; Irving, Thomas C. (IIT); (Loyola)

    2010-05-25

    The Frank-Starling law of the heart describes the interrelationship between end-diastolic volume and cardiac ejection volume, a regulatory system that operates on a beat-to-beat basis. The main cellular mechanism that underlies this phenomenon is an increase in the responsiveness of cardiac myofilaments to activating Ca{sup 2+} ions at a longer sarcomere length, commonly referred to as myofilament length-dependent activation. This review focuses on what molecular mechanisms may underlie myofilament length dependency. Specifically, the roles of inter-filament spacing, thick and thin filament based regulation, as well as sarcomeric regulatory proteins are discussed. Although the 'Frank-Starling law of the heart' constitutes a fundamental cardiac property that has been appreciated for well over a century, it is still not known in muscle how the contractile apparatus transduces the information concerning sarcomere length to modulate ventricular pressure development.

  10. Numerical Analysis on the Formation of Fracture Network during the Hydraulic Fracturing of Shale with Pre-Existing Fractures

    Directory of Open Access Journals (Sweden)

    Jianming He

    2017-05-01

    Full Text Available In this paper, configurations of pre-existing fractures in cubic rock blocks were investigated and reconstructed for the modeling of experimental hydraulic fracturing. The fluid-rock coupling process of hydraulic fracturing was simulated based on the displacement discontinuities method. The numerical model was validated against the related laboratory experiments. The stimulated fracture configurations under different conditions can be clearly shown using the validated numerical model. First, a dominated fracture along the maximum principle stress direction is always formed when the stress difference is large enough. Second, there are less reopened pre-existing fractures, more newly formed fractures and less shear fractures with the increase of the cohesion value of pre-existing fractures. Third, the length of the stimulated shear fracture decreases rapidly with the increase of the friction coefficient, while the length of the tensile fracture has no correlation to the fiction coefficient. Finally, the increase of the fluid injection rate is favorable to the formation of a fracture network. The unfavorable effects of the large stress difference and the large cohesion of pre-existing fractures can be partly suppressed by an increase of the injection rate in the hydraulic fracturing treatment. The results of this paper are useful for understanding fracture propagation behaviors during the hydraulic fracturing of shale reservoirs with pre-existing fractures.

  11. [(Impending) pathological fracture].

    Science.gov (United States)

    Sutter, P M; Regazzoni, P

    2002-01-01

    Pathological fractures will be encountered in increasing frequency due to more patients with cancer, surviving a longer period. The skeleton is the third most frequent localization for metastases. Breast cancer is still the most common primary tumor, but bone metastases from lung cancer seem to be diagnosed more and more. Despite of finding metastases most often in the spinal column, fractures are seen mostly at the femoral site. A pathological fracture and, in almost all cases, an impending fracture are absolute indication for operation. An exact definition of an "impending fracture" is still lacking; it is widely accepted, that 50 per cent of bone mass must be destroyed before visualization in X-ray is possible, thus defining an impending fracture. The score system by Mirels estimates the fracture risk by means of four parameters (localization, per cent of destructed bone mass, type of metastasis, pain). Improving quality of life, relieving pain, preferably with a single operation and a short length of stay are the goals of (operative) treatment. For fractures of the proximal femur, prosthetic replacement, for fractures of the subtrochanteric region or the shaft, intramedullary nails are recommended. Postoperative radiation therapy possibly avoids tumor progression. In patient with a good long term prognosis, tumor should be removed locally aggressive.

  12. A two-scale damage model with material length

    Science.gov (United States)

    Dascalu, Cristian

    2009-09-01

    The Note presents the formulation of a class of two-scale damage models involving a micro-structural length. A homogenization method based on asymptotic developments is employed to deduce the macroscopic damage equations. The damage model completely results from energy-based micro-crack propagation laws, without supplementary phenomenological assumptions. We show that the resulting two-scale model has the property of capturing micro-structural lengths. When damage evolves, the micro-structural length is given by the ratio of the surface density of energy dissipated during the micro-crack growth and the macroscopic damage energy release rate per unit volume of the material. The use of fracture criteria based on resistance curves or power laws for sub-critical growth of micro-cracks leads to quasi-brittle and, respectively, time-dependent damage models. To cite this article: C. Dascalu, C. R. Mecanique 337 (2009).

  13. Hip Fracture

    Science.gov (United States)

    Diseases and Conditions Hip fracture By Mayo Clinic Staff A hip fracture is a serious injury, with complications that can be life-threatening. The risk of hip fracture rises with age. Older people are at a ...

  14. Trabecular Plate Loss and Deteriorating Elastic Modulus of Femoral Trabecular Bone in Intertrochanteric Hip Fractures

    Institute of Scientific and Technical Information of China (English)

    Ji Wang; Bin Zhou; Ian Parkinson; C. David L. Thomas; John G. Clement; Nick Fazzalari; X. Edward Guo

    2013-01-01

    Osteoporotic hip fracture is associated with significant trabecular bone loss, which is typically characterized as low bone density by dual-energy X-ray absorptiometry (DXA) and altered microstructure by micro-computed tomography (µCT). Emerging morphological analysis techniques, e.g. individual trabecula segmentation (ITS), can provide additional insights into changes in plate-like and rod-like trabeculae, two major micro-structural types serving different roles in determining bone strength. Using ITS, we evaluated trabecular microstructure of intertrochanteric bone cores obtained from 23 patients undergoing hip replacement surgery for intertrochanteric fracture and 22 cadaveric controls. Micro-finite element (µFE) analyses were performed to further understand how the abnormalities seen by ITS might translate into effects on bone strength. ITS analyses revealed that, near fracture site, plate-like trabeculae were seriously depleted in fracture patients, but trabecular rod volume was maintained. Besides, decreased plate area and rod length were observed in fracture patients. Fracture patients also showed decreased elastic moduli and shear moduli of trabecular bone. These results provided evidence that in intertrochanteric hip fracture, preferential loss of plate-like trabeculae led to more rod-like microstructure and deteriorated mechanical competence adjacent to the fracture site, which increased our understanding of the biomechanical pathogenesis of hip fracture in osteoporosis.

  15. Hydraulic fracturing with chlorine dioxide cleanup

    Energy Technology Data Exchange (ETDEWEB)

    Williams, D.A.; Newlove, J.C.; Horton, R.L.

    1990-10-23

    This patent describes a method for fracturing a subterranean formation penetrated by a wellbore. It comprises: injecting a fracturing fluid into the formation to form a vertical fracture therein, the fracturing fluid being gelled with a polymer selected from guar, guar derivatives, acrylamide, acrylamide derivatives, cellulose, cellulose derivatives, and mixtures thereof and crosslinked with an organometallic crosslinking compound and having temperature stability above about 175{degrees} F.; packing the fracture with particulate propping agent; backflowing fluids from the formation through the propped fracture to remove a portion of the polymer; injecting at matrix rates sufficient aqueous solution of chlorine dioxide down the wellbore and into the propped fracture to penetrate at least 60 feet of the propped fracture length and contact polymer in the fracturing fluid and polymer residue in the propped fracture and on the fracture walls, the amount of the chlorine dioxide in the aqueous medium being sufficient to degrade polymer in the fracturing fluid and polymer residue; permitting the chlorine dioxide to remain in contact with the polymer in the fracturing fluid and with the polymer residue on the fracture walls and in the fracture for sufficient time to degrade the polymer thereby reducing the fracturing fluid viscosity and dissolving portions of the polymer residue; and flowing formation fluid from the formation through the propped fracture and into the wellbore to remove substantial portions of the polymer and degraded polymer from the fracture.

  16. 128层螺旋CT扫描容积重建诊断肋骨骨折的临床价值%Value of volume vendering after 128-slice spiral CT in the diagnosis of rib fracture

    Institute of Scientific and Technical Information of China (English)

    董延鸣; 徐伟; 石渠

    2013-01-01

    目的 探讨128 层螺旋CT扫描容积重建诊断肋骨骨折的临床价值.方法 回顾性分析100 例378根肋骨及20 根肋软骨骨折病例,采用薄层(0.625 mm)重组、容积再现(VR)重建技术进行肋骨及肋软骨重建,并在工作站上进行多角度、全方位动态观察.结果 100 例肋骨发现320 根378 处骨折,其中多发骨折85 例305 根,单发性骨折15 例;单侧肋骨骨折78 例257 根,双侧骨折22 例共121 根;肋软骨骨折20 例,不全性骨折45 根.合并肺挫伤35 例,气胸26 例,血气胸18 例,脾挫裂伤8 例、肝挫裂伤3 例.结论 胸部外伤患者行128 层螺旋CT常规扫描后,薄层重组结合容积重建对肋骨骨折及其并发症的诊断有非常重要的价值.%Objective To investigate the value of volume vendering after 128-slice spiral CT in the diagnosis of rib fracture. Methods The clinical data of 100 patients (378 rib fractures and 20 costalcartilages fractures) were retrospectively analyzed. The thin-slice reconstruction (0.652 mm), volume vendering (VR) were applied for the reconstruction of rib and costalcartilages. Multi-angel, comprehensive, dynamic observation in the workstation was performed. Results A total of 378 rib fractures in 320 ribs were found, including multiple rib fracture in 305 ribs in 85 patients, comminuted rib fracture in 15 ribs in 15 patients, of which 257 fractured ribs were on the same side (in 78 patients) and 121 were on two sides (in 22 patients). A total of 20 patients with costalcartilages fractures were found, with 45 ribs of incomplete rib fracture. Thirty-five patients were found with lung contusion, 26 with pneumothorax, 18 with hemopnemothorax, 8 with dampened spleen and 3 with dampened liver. Conclusion Thin-slice reconstruction and volume vendering after 128-slice spiral CT scan has very important value in the diagnosis of ribs fracture and complications in patients with chest trauma.

  17. Flame Length

    Data.gov (United States)

    Earth Data Analysis Center, University of New Mexico — Flame length was modeled using FlamMap, an interagency fire behavior mapping and analysis program that computes potential fire behavior characteristics. The tool...

  18. Axial length and orbital volume analysis of PHPV eyes in Children%永存原始玻璃体增生症患儿眼轴长度及眶容积分析

    Institute of Scientific and Technical Information of China (English)

    胡毅倩; 董洋; 王诗园; 冯华章; 周秀莉; 余文晶

    2014-01-01

    目的 初步探讨永存原始玻璃体增生症(persistent hyperplastic primary vitreous,PHPV)患儿眼眶发育状况及其与眼轴发育、病变类型间关系.方法 对2009年3月至2011年8月在上海交通大学医学院附属新华医院就诊的18例PHPV患儿进行眼部超声检查、眼轴长度测量及CT三维重建眶容积分析.结果 患儿平均年龄10个月(最小56 d,最大24个月),均单眼发病.患眼轴长(17.8±3.2) mm,眶容积(12.5±2.9) cm3;健眼轴长(20.4±2.7) mm,眶容积(13.5±3.1) cm3.患眼轴长及眶容积均显著<对侧眼,差异有统计学意义(t值=-5.517、-5.701,P值=3.772× 104、2.598×10-5).根据超声特征,按病变累及玻璃体前部、后部或全程,分成A组(4例)、B组(5例)、C组(9例),计三组.A组患眼与对侧眼间眼轴长度及眶容积差异均无统计学意义(t值=-1.151、-2.485,P值=0.333、0.089);B组患眼轴长及眶容积均<对侧眼(t值=-2.835、-2.809,P值=0.047、0.048).C组患眼轴长及眶容积均显著<对侧眼(t值=-8.472、-5.365,P值=2.885×10-5、0.001).C组双眼轴长差值显著>A、B两组(P值=0.001、0.008),C组双眼眶容积差均值最大,但与其他组比较差异无统计学意义(P>0.05).眶容积与眼轴长度呈较强差异有统计学意义(r=0.486,P=0.003).双眼眶容积差值与眼轴长度差值差异有统计学意义(r=0.560,P=0.016).结论 PHPV患眼眼轴发育及眶容积发育均受阻,两者存在正相关关系.单纯前部玻璃体增殖影响不明显,前后混合型影响显著.CT三维重建是有效的眶容积测量方法.%Objective To study the orbital volume development and its relationship with the axial length and pathological type in children PHPV eyes.Methods Eighteen cases of children who were diagnosed PHPV in Xinhua Hospital affiliated to Medical School of Shanghai Jiaotong University from March 2009 to August 2011 performed ultrasonography of the eye and reconstructed computed tomography of the orbital

  19. Growth Kinematics of Opening-Mode Fractures

    Science.gov (United States)

    Eichhubl, P.; Alzayer, Y.; Laubach, S.; Fall, A.

    2014-12-01

    Fracture aperture is a primary control on flow in fractured reservoirs of low matrix permeability including unconventional oil and gas reservoirs and most geothermal systems. Guided by principles of linear elastic fracture mechanics, fracture aperture is generally assumed to be a linear function of fracture length and elastic material properties. Natural opening-mode fractures with significant preserved aperture are observed in core and outcrop indicative of fracture opening strain accommodated by permanent solution-precipitation creep. Fracture opening may thus be decoupled from length growth if the material effectively weakens after initial elastic fracture growth by either non-elastic deformation processes or changes in elastic properties. To investigate the kinematics of fracture length and aperture growth, we reconstructed the opening history of three opening-mode fractures that are bridged by crack-seal quartz cement in Travis Peak Sandstone of the SFOT-1 well, East Texas. Similar crack-seal cement bridges had been interpreted to form by repeated incremental fracture opening and subsequent precipitation of quartz cement. We imaged crack-seal cement textures for bridges sampled at varying distance from the tips using scanning electron microscope cathodoluminescence, and determined the number and thickness of crack-seal cement increments as a function of position along the fracture length and height. Observed trends in increment number and thickness are consistent with an initial stage of fast fracture propagation relative to aperture growth, followed by a stage of slow propagation and pronounced aperture growth. Consistent with fluid inclusion observations indicative of fracture opening and propagation occurring over 30-40 m.y., we interpret the second phase of pronounced aperture growth to result from fracture opening strain accommodated by solution-precipitation creep and concurrent slow, possibly subcritical, fracture propagation. Similar deformation

  20. 鄂尔多斯盆地致密油水平井体积压裂优化设计%Optimization design for volume fracturing of horizontal wells in tight oil reservoir of Ordos Basin

    Institute of Scientific and Technical Information of China (English)

    白晓虎; 齐银; 陆红军; 段鹏辉; 顾燕凌; 吴甫让

    2015-01-01

    鄂尔多斯盆地长7致密油储层致密、油藏低压。储层天然微裂缝发育程度和岩石脆性评价表明,盆地致密油储层物性对水平井分段体积压裂具有良好的适应性。以提高水平井多段压裂井网形式和布缝的匹配性为目的,优化了与注采井网相适配的施工参数,结果表明,实现体积压裂的排量为4~8 m3/min,单段砂量40~80 m3,入地液量300~700 m3,并形成了“低黏液体造缝、高黏液体携砂、组合粒径支撑剂、不同排量注入”的混合压裂设计模式。矿场井下微地震监测对比了体积压裂与常规压裂对裂缝扩展形态的影响,结果显示致密储层采用体积压裂的改造体积和复杂指数是常规压裂的2倍左右,且与井网适配性良好。通过开展致密油开发矿场先导性试验,水平井单井初期产量达到8~10 t/d,第1年累计产油量达2000 t左右,且无裂缝性见水井,证明对于鄂尔多斯盆地的致密油开发,采用水平井五点井网+混合水体积压裂可以获得较高的单井产量和良好的开发效益。该项技术对其他油田的非常规储层开发有一定的借鉴意义。%Chang 7 tight oil reservoir of Ordos Basin features tight and low-pressure reservoir. It is shown from natural microfracture development degree and rock brittleness assessment of the reservoir that, properties of tight oil reservoir of the basin are highly adaptable to segmented volume fracturing of horizontal wells. The construction parameters which match with lfood pattern are optimized for the purpose of improving compatibility between multi-segment fracturing pattern form and fracture distribution of horizontal wells, and results indicate that volume fracturing is realized by displacement between 4 m3/min to 8m3/min, single-segment sand amount between 40 m3 to 80 m3, and buried liquid amount between 300 m3 to 700 m3. The mixed fracturing design mode of fracture formation by low

  1. Fractured reservoir analogs: case study of paelocirculation markers on Tamariu's Granite.

    Science.gov (United States)

    Bertrand, Lionel; Legarzic, Edouard; Geraud, Yves; Diraison, Marc

    2013-04-01

    In fractured crystalline reservoirs, the grain matrix has in general a very low permeability and the fluid flow is localized in the fracture pattern. The flow in such fracture network is generally complicated to characterize, in on hand because many parameters (length, connectivity, aperture, tortuosity,…) are acting on the fluid flow, in other hand because the fractures at a reservoir scale using seismic data are not easy to characterize. In fact, the only information we have on fracture in buried reservoir are at a local scale with boreholes and at a kilometric scale with seismic. The study of field analogs is one way to establish a better comprehension of the fracture pattern between those two scales. Regional and outcrop studies on Tamariu's granite, which outcrops on the Catalonian Coastal Ranges, has permit the characterization of the faults and fractures at different scales. The faults network defines different sizes of structural blocks bordered by faults. In an unfaulted structural block, the granite exhibits a fracture network filled with hydrothermal carbonates, markers of important paleofluid circulation. These carbonates were analysed at different scales using fracture mapping, calcimetry and microscopy on thin- sections in order to define the location and the volume of the carbonates precipitation and to have an estimation of the paleo-porosity used by the fluids in the fracture network. With precise fracture maps, we analysed the principal flow direction and the nature of the hydrothermal deposits. The same maps, combined with calcimetry measurements, allow us to quantify the 2D volume of porosity used by the paleofluids. We have quantified the carbonates in different areas of percolation: the main veins, breccias cimented by carbonates, fractured granite and poorly fractured granite. The percentage of paleofluids markers reaches to 3% of the granitic rock, and the main part of them are localized in some fractured corridor composed of mains veins

  2. CT of pelvic fractures

    Energy Technology Data Exchange (ETDEWEB)

    Falchi, Marco E-mail: marcofalchi@yahoo.it; Rollandi, Gian Andrea

    2004-04-01

    Although magnetic resonance imaging has become the dominant modality for cross-sectional musculo-skeletal imaging, the widespread availability, speed, and versatility of computed tomography (CT) continue to make it a mainstay of emergency room (ER) diagnostic imaging. Pelvic ring and acetabular fractures occur as the result of significant trauma secondary to either a motor vehicle accident or a high-velocity fall. These injuries are correlated with significant morbidity and mortality, both from the complications of pelvic ring fractures and from commonly associated injuries. The most commonly used classification of pelvic and acetabular fractures has been based on conventional radiographs that are, in the majority of cases, sufficient to determine the type of injury. However, because of the complexity of pelvic and acetabular fractures, precise pathological anatomy is not easily demonstrated by routine radiographs and in many cases details of fractures are not visible. Moreover, the insufficient co-operation of the patient or the difficulty of maintaining special positions can be overcome by using computed tomography. Spiral computed tomography provides information regarding the extent of the fractures and is complementary to radiography for ascertaining the spatial arrangement of fracture fragments. Spiral computed tomography is an effective tool for understanding complex fracture patterns, particularly when combined with multi-planar reconstruction two-dimensional (MPR 2D) reformatted images or three-dimensional images (3D) images. Including these techniques of reconstruction in routine pelvic imaging protocols can change management in a significant number of cases. Subtle fractures, particularly those oriented in the axial plane, are better seen on MPR images or 3D volume-rendered images. Complex injuries can be better demonstrated with 3D volume-rendered images, and complicated spatial information about the relative positions of fracture fragments can be easily

  3. Forced expiratory volume in one second predicts length of stay and in-hospital mortality in patients undergoing cardiac surgery: a retrospective cohort study.

    Directory of Open Access Journals (Sweden)

    David A McAllister

    Full Text Available OBJECTIVE: An aging population and increasing use of percutaneous therapies have resulted in older patients with more co-morbidity being referred for cardiac surgery. Objective measurements of physiological reserve and severity of co-morbid disease are required to improve risk stratification. We hypothesised that FEV1 would predict mortality and length of stay following cardiac surgery. METHODS: We assessed clinical outcomes in 2,241 consecutive patients undergoing coronary artery bypass grafting and/or valve surgery from 2001 to 2007 in a regional cardiac centre. Generalized linear models of the association between FEV1 and length of hospital stay and mortality were adjusted for age, sex, height, body mass index, socioeconomic status, smoking, cardiovascular risk factors, long-term use of bronchodilators or steroids for lung disease, and type and urgency of surgery. FEV1 was compared to an established risk prediction model, the EuroSCORE. RESULTS: Spirometry was performed in 2,082 patients (93% whose mean (SD age was 67 (10 years. Median hospital stay was 3 days longer in patients in the lowest compared to the highest quintile for FEV1, 1.35-fold higher (95% CI 1.20-1.52; p<0.001. The adjusted odds ratio for mortality was increased 2.11-fold (95% CI 1.45-3.08; p<0.001 per standard deviation decrement in FEV1 (800 ml. FEV1 improved discrimination of the EuroSCORE for mortality. Similar associations were found after excluding people with known pulmonary disease and/or airflow limitation on spirometry. CONCLUSIONS: Reduced FEV1 strongly predicted increased length of stay and in-hospital mortality following cardiac surgery. FEV1 is a widely available measure of physiological health that may improve risk stratification of complex patients undergoing cardiac surgery and should be evaluated for inclusion in new prediction tools.

  4. Validation of Navigation Ultrasound for Clavicular Length Measurement

    DEFF Research Database (Denmark)

    Høj, Anders Thorsmark; Villa, Chiara; Christensen, Ole M

    2017-01-01

    Accurate clavicular length measurement is considered important for the selection of patients requiring surgical treatment after a midclavicular fracture. As radiographic length measurements can be inaccurate to varying degrees, new measurement methods are needed. Use of novel technology, navigati...

  5. Epidemiological study on talus fractures

    Directory of Open Access Journals (Sweden)

    Marcos Hideyo Sakaki

    2014-08-01

    Full Text Available Objective:To analyze the characteristics of patients with talus fractures and the injuries that they present.Methods:Retrospective analysis on patients hospitalized in the Institute of Orthopedics and Traumatology, Hospital das Clínicas, School of Medicine of the University of São Paulo, between 2006 and 2011, with talus fractures. Patient profile parameters, risk factors, fracture characteristics, treatment data and acute complications were analyzed.Results:Analysis on 23 cases showed that men were more affected than women, with a ratio of 4.8:1. The most frequent trauma mechanism was traffic accidents, followed by falls from a height. The most frequent type of fracture was at the neck of the talus, with 17 cases. Among the 23 cases, seven had peritalar dislocation at the time of presentation, four had exposed fractures and 11 presented other associated fractures. The mean length of time between the trauma and the definitive treatment was six days, while the mean length of hospital stay was 11 days. Three patients presented acute postoperative complications.Conclusion:Talus fractures occurred most commonly in the region of the talar neck and most frequently in young males who suffered high-energy trauma. In almost half of the cases, there were other associated fractures. The length of hospital stay was 11 days.

  6. [Atlas fractures].

    Science.gov (United States)

    Schären, S; Jeanneret, B

    1999-05-01

    Fractures of the atlas account for 1-2% of all vertebral fractures. We divide atlas fractures into 5 groups: isolated fractures of the anterior arch of the atlas, isolated fractures of the posterior arch, combined fractures of the anterior and posterior arch (so-called Jefferson fractures), isolated fractures of the lateral mass and fractures of the transverse process. Isolated fractures of the anterior or posterior arch are benign and are treated conservatively with a soft collar until the neck pain has disappeared. Jefferson fractures are divided into stable and unstable fracture depending on the integrity of the transverse ligament. Stable Jefferson fractures are treated conservatively with good outcome while unstable Jefferson fractures are probably best treated operatively with a posterior atlanto-axial or occipito-axial stabilization and fusion. The authors preferred treatment modality is the immediate open reduction of the dislocated lateral masses combined with a stabilization in the reduced position using a transarticular screw fixation C1/C2 according to Magerl. This has the advantage of saving the atlanto-occipital joints and offering an immediate stability which makes immobilization in an halo or Minerva cast superfluous. In late instabilities C1/2 with incongruency of the lateral masses occurring after primary conservative treatment, an occipito-cervical fusion is indicated. Isolated fractures of the lateral masses are very rare and may, if the lateral mass is totally destroyed, be a reason for an occipito-cervical fusion. Fractures of the transverse processes may be the cause for a thrombosis of the vertebral artery. No treatment is necessary for the fracture itself.

  7. A 3-Dimensional discrete fracture network generator to examine fracture-matrix interaction using TOUGH2

    Energy Technology Data Exchange (ETDEWEB)

    Ito, Kazumasa; Yongkoo, Seol

    2003-04-09

    Water fluxes in unsaturated, fractured rock involve the physical processes occurring at fracture-matrix interfaces within fracture networks. Modeling these water fluxes using a discrete fracture network model is a complicated effort. Existing preprocessors for TOUGH2 are not suitable to generate grids for fracture networks with various orientations and inclinations. There are several 3-D discrete-fracture-network simulators for flow and transport, but most of them do not capture fracture-matrix interaction. We have developed a new 3-D discrete-fracture-network mesh generator, FRACMESH, to provide TOUGH2 with information about the fracture network configuration and fracture-matrix interactions. FRACMESH transforms a discrete fracture network into a 3 dimensional uniform mesh, in which fractures are considered as elements with unique rock material properties and connected to surrounding matrix elements. Using FRACMESH, individual fractures may have uniform or random aperture distributions to consider heterogeneity. Fracture element volumes and interfacial areas are calculated from fracture geometry within individual elements. By using FRACMESH and TOUGH2, fractures with various inclinations and orientations, and fracture-matrix interaction, can be incorporated. In this paper, results of flow and transport simulations in a fractured rock block utilizing FRACMESH are presented.

  8. Root fractures

    DEFF Research Database (Denmark)

    Andreasen, Jens Ove; Christensen, Søren Steno Ahrensburg; Tsilingaridis, Georgios

    2012-01-01

    The purpose of this study was to analyze tooth loss after root fractures and to assess the influence of the type of healing and the location of the root fracture. Furthermore, the actual cause of tooth loss was analyzed.......The purpose of this study was to analyze tooth loss after root fractures and to assess the influence of the type of healing and the location of the root fracture. Furthermore, the actual cause of tooth loss was analyzed....

  9. Stress Fractures

    Science.gov (United States)

    Stress fractures Overview Stress fractures are tiny cracks in a bone. They're caused by repetitive force, often from overuse — such as repeatedly jumping up and down or running long distances. Stress fractures can also arise from normal use of ...

  10. Estimating exposed pulp lengths of tusks in the African elephant (Loxodonta africana africana : article

    Directory of Open Access Journals (Sweden)

    G. Steenkamp

    2008-05-01

    Full Text Available Captive and wild African elephants frequently suffer tusk fractures. Several institutions shorten the tusks of captive elephants to reduce fractures and injury as a result of behaviour within enclosures. Fracturing or coronal amputations that expose pulp lead to pain for the elephant. Estimating coronal pulp lengths may thus help to minimise the risk of pulp exposure during amputations. We aimed to determine the length of the pulp beyond the lip margin from an external tusk characteristic. Tusks collected from elephants in Namibia and the Kruger National Park had similar morphological relationships. This statistical property allowed us to correct for missing data in our data sets. Pulp volume and pulp length correlated with tusk circumference at the lip. Even so, the circumference at the lip could not predict the length of the pulp in the crown external to the lip. Our findings suggest that tusks, irrespective of sex or age, amputated further than 300 mm from the lip should not expose pulp.

  11. Simulation study of the VAPEX process in fractured heavy oil system at reservoir conditions

    Energy Technology Data Exchange (ETDEWEB)

    Azin, Reza; Ghotbi, Cyrus [Department of Chemical and Petroleum Engineering, Sharif Univ. Tech., Tehran (Iran); Kharrat, Riyaz; Rostami, Behzad [Petroleum University of Technology Research Center, Tehran (Iran); Vossoughi, Shapour [4132C Learned Hall, Department of Chemical and Petroleum Engineering, Kansas University, Lawrence, KS (United States)

    2008-01-15

    The Vapor Extraction (VAPEX) process, a newly developed Enhanced Oil Recovery (EOR) process to recover heavy oil and bitumen, has been studied theoretically and experimentally and is found a promising EOR method for certain heavy oil reservoirs. In this work, a simulation study of the VAPEX process was made on a fractured model, which consists of a matrix surrounded by horizontal and vertical fractures. The results show a very interesting difference in the pattern of solvent flow in fractured model compared with the conventional model. Also, in the fractured system, due to differences in matrix and fracture permeabilities, the solvent first spreads through the fractures and then starts diffusing into matrix from all parts of the matrix. Thus, the solvent surrounds the oil bank, and an oil rather than the solvent chamber forms and shrinks as the process proceeds. In addition, the recovery factor is higher at lower solvent injection rates for a constant pore volume of the solvent injected into the model. Also, the diffusion process becomes important and higher recoveries are obtained at low injection rates, provided sufficient time is given to the process. The effect of inter-connectivity of the surrounding fractures was studied by making the side vertical fractures shorter than the side length of the model. It was observed that inter-connectivity of the fractures affects the pattern of solvent distribution. Even for the case of side fractures being far apart from the bottom fracture, the solvent distribution in the matrix was significantly different than that in the model without fractures. Combination of diffusion phenomenon and gravity segregation was observed to be controlling factors in all VAPEX processes simulated in fractured systems. The early breakthrough of the solvent for the case of matrix surrounded by the fracture partially inhibited diffusion of the solvent into the oil and consequently the VAPEX process became the least effective. It is concluded

  12. Subduction of fracture zones

    Science.gov (United States)

    Constantin Manea, Vlad; Gerya, Taras; Manea, Marina; Zhu, Guizhi; Leeman, William

    2013-04-01

    Since Wilson proposed in 1965 the existence of a new class of faults on the ocean floor, namely transform faults, the geodynamic effects and importance of fracture zone subduction is still little studied. It is known that oceanic plates are characterized by numerous fracture zones, and some of them have the potential to transport into subduction zones large volumes of water-rich serpentinite, providing a fertile water source for magma generated in subduction-related arc volcanoes. In most previous geodynamic studies, subducting plates are considered to be homogeneous, and there is no clear indication how the subduction of a fracture zone influences the melting pattern in the mantle wedge and the slab-derived fluids distribution in the subarc mantle. Here we show that subduction of serpentinized fracture zones plays a significant role in distribution of melt and fluids in the mantle wedge above the slab. Using high-resolution tree-dimensional coupled petrological-termomechanical simulations of subduction, we show that fluids, including melts and water, vary dramatically in the region where a serpentinized fracture zone enters into subduction. Our models show that substantial hydration and partial melting tend to concentrate where fracture zones are being subducted, creating favorable conditions for partially molten hydrous plumes to develop. These results are consistent with the along-arc variability in magma source compositions and processes in several regions, as the Aleutian Arc, the Cascades, the Southern Mexican Volcanic Arc, and the Andean Southern Volcanic Zone.

  13. Characterizing Fracture Spatial Patterns by Using Semivariograms

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Semivariogram is applied to fracture data obtained from detailed scanline surveys of nine field sites in western New York, USA in order to investigate the spatial patterns of natural fractures. The length of the scanline is up to 36 m. How both fracture spacing and fracture length vary with distance is determined through semivariogram calculations. In this study, the authors developed a FORTRAN program to resample the fracture data from the scanline survey. By calculating experimental semivariogram, the authors found five different types of spatial patterns that can be described by linear, spherical, reversed spherical, polynomial I (for a0) models, of which the last three are newly proposed in this study. The well-structured semivariograms of fracture spacing and length indicate that both the location of the fractures and the length distribution within their structure domains are not random. The results of this study also suggest that semivariograms can provide useful information in terms of spatial correlation distance for fracture location and fracture length. These semivariograms can also be utilized to design more efficient sampling schemes for further surveys, as well as to define the limits of highly probable extrapolation of a structure domain.

  14. Fractal modeling of natural fracture networks

    Energy Technology Data Exchange (ETDEWEB)

    Ferer, M.; Dean, B.; Mick, C.

    1995-06-01

    West Virginia University will implement procedures for a fractal analysis of fractures in reservoirs. This procedure will be applied to fracture networks in outcrops and to fractures intersecting horizontal boreholes. The parameters resulting from this analysis will be used to generate synthetic fracture networks with the same fractal characteristics as the real networks. Recovery from naturally fractured, tight-gas reservoirs is controlled by the fracture network. Reliable characterization of the actual fracture network in the reservoir is severely limited. The location and orientation of fractures intersecting the borehole can be determined, but the length of these fractures cannot be unambiguously determined. Because of the lack of detailed information about the actual fracture network, modeling methods must represent the porosity and permeability associated with the fracture network, as accurately as possible with very little a priori information. In the sections following, the authors will (1) present fractal analysis of the MWX site, using the box-counting procedure; (2) review evidence testing the fractal nature of fracture distributions and discuss the advantages of using the fractal analysis over a stochastic analysis; and (3) present an efficient algorithm for producing a self-similar fracture networks which mimic the real MWX outcrop fracture network.

  15. Irradiation effects on fracture toughness of two high-copper submerged-arc welds, HSSI Series 5. Volume 1, Main report and Appendices A, B, C, and D

    Energy Technology Data Exchange (ETDEWEB)

    Nanstad, R.K.; Haggag, F.M.; McCabe, D.E.; Iskander, S.K.; Bowman, K.O. [Oak Ridge National Lab., TN (United States); Menke, B.H. [Materials Engineering Associates, Inc., Lanham, MD (United States)

    1992-10-01

    The Fifth Irradiation Series in the Heavy-Section Steel Irradiation Program obtained a statistically significant fracture toughness data base on two high-copper (0.23 and 0.31 wt %) submerged-arc welds to determine the shift and shape of the K{sub Ic} curve as a consequence of irradiation. Compact specimens with thicknesses to 101.6 mm (4 in) in the irradiated condition and 203.2 mm (8 in) in the unirradiated condition were tested, in addition to Charpy impact, tensile, and drop-weight specimens. Irradiations were conducted at a nominal temperature of 288{degree}C and an average fluence of 1.5 {times} 10{sup 19} neutrons/cm{sup 2} (>l MeV). The Charpy 41-J temperature shifts are about the same as the corresponding drop-weight NDT temperature shifts. The irradiated welds exhibited substantial numbers of cleavage pop-ins. Mean curve fits using two-parameter (with fixed intercept) nonlinear and linearized exponential regression analysis revealed that the fracture toughness 100 MPa{lg_bullet}{radical}m shifts exceeded the Charpy 41-J shifts for both welds. Analyses of curve shape changes indicated decreases in the slopes of the fracture toughness curves, especially for the higher copper weld. Weibull analyses were performed to investigate development of lower bound curves to the data, including the use of a variable K{sub min} parameter which affects the curve shape.

  16. [Acetabular fractures].

    Science.gov (United States)

    Gänsslen, A; Oestern, H J

    2011-12-01

    Treatment of acetabular fractures requires extensive knowledge of the bony anatomy, the amount of possible exposure of the bone with the selected approaches and fracture type-dependent indications of operative treatment. Classification of the fracture with detailed analysis of the fracture morphology is the basis for decision making and planning. The primary treatment aim is the anatomic reconstruction of the acetabulum which results in optimal long-term results.The basis of this overview is the presentation of standard treatment concepts in acetabular fracture surgery. Beside characteristics of the acetabular bony anatomy, biomechanical and pathomechanical principles and the relevant radiological anatomy, the treatment options, both conservative and operative and basic principles of the indications for standard surgical approaches will be discussed.The special fracture type is discussed in detail regarding incidence, injury mechanism, concomitant injuries, options for conservative and operative treatment, quality of operative reduction and long-term results.Furthermore, epidemiological data on typical postoperative complications are evaluated.

  17. Classification of subtrochanteric femoral fractures.

    Science.gov (United States)

    Loizou, C L; McNamara, I; Ahmed, K; Pryor, G A; Parker, M J

    2010-07-01

    A review of the literature identified 15 different classification methods for subtrochanteric femoral fractures. Only eight of those classifications defined the area of bone, which constituted a subtrochanteric fracture. The actual length of femur defined as the subtrochanteric zone varied from 3 cm up to the level of the femoral isthmus. There was no agreement between the different classifications regarding the proximal and distal border or for those fractures, which traverse anatomical boundaries. In the various classifications, fractures were subdivided into 2-15 subgroups. The majority of the identified studies were unable to find the classifications useful in either determining treatment or predicting the outcome after treatment. We subdivided subtrochanteric fractures into three types based on the degree of fracture comminution. We examined the inter- and intra-observer agreement of our recommended classification. One orthopaedic consultant, one specialist hip fracture surgeon, two trainee registrar orthopaedic surgeons and one specialty trainee in orthopaedics, on two different occasions, 8 weeks apart, independently classified the radiographs of 20 patients with a subtrochanteric fracture. The mean kappa value for inter- and intra-observer variation was 0.71 and 0.79, respectively, with both showing substantial agreement and, therefore, this simpler classification is recommended. Based on the review of previous classification methods, we also recommend that the subtrochanteric zone be defined as the one in which the fracture line crossing the femur is predominantly within the area of bone extending 5 cm below the lower border of the lesser trochanter.

  18. Sports fractures.

    OpenAIRE

    DeCoster, T. A.; Stevens, M. A.; Albright, J. P.

    1994-01-01

    Fractures occur in athletes and dramatically influence performance during competitive and recreational activities. Fractures occur in athletes as the result of repetitive stress, acute sports-related trauma and trauma outside of athletics. The literature provides general guidelines for treatment as well as a variety of statistics on the epidemiology of fractures by sport and level of participation. Athletes are healthy and motivated patients, and have high expectations regarding their level o...

  19. Topological impact of constrained fracture growth

    Directory of Open Access Journals (Sweden)

    Sigmund Mongstad Hope

    2015-09-01

    Full Text Available The topology of two discrete fracture network models is compared to investigate the impact of constrained fracture growth. In the Poissonian discrete fracture network model the fractures are assigned length, position and orientation independent of all other fractures, while in the mechanical discrete fracture network model the fractures grow and the growth can be limited by the presence of other fractures. The topology is found to be impacted by both the choice of model, as well as the choice of rules for the mechanical model. A significant difference is the degree mixing. In two dimensions the Poissonian model results in assortative networks, while the mechanical model results in disassortative networks. In three dimensions both models produce disassortative networks, but the disassortative mixing is strongest for the mechanical model.

  20. Hamate fractures.

    Science.gov (United States)

    Sarabia Condés, J M; Ibañez Martínez, L; Sánchez Carrasco, M A; Carrillo Julia, F J; Salmerón Martínez, E L

    2015-01-01

    The purpose of this paper is to present our experience in the treatment of the fractures of the hamate and to make a review of the literature on this topic. We retrospectively reviewed 10 patients treated in our clinic between 2005-2012 suffering from fractures of the hamate. Six cases were fractures of the body and four were fractures of the hamate. Five cases were of associated injuries. Diagnostic delay ranged from 30 days to 2 years. Patient follow-up ranged from 1 to 10 years. Patient satisfaction was evaluated using the DASH questionnaire. Five patients with a fracture of the body underwent surgery, and one was treated conservatively. Two patients with fracture of the hook of the hamate were treated with immobilization, and two more patients had the fragment removed. The grip strength and the digital clip were reduced in 2 cases. Flexion and extension of the wrist was limited in 3 cases. The mobility of the fingers was normal in all the cases, except in one. The results obtained from the DASH questionnaire were normal in all the cases, except in one case of fracture of the hamate, and in two cases of fracture of the body. The surgical treatment should reduce the dislocation and stabilize the injuries with osteosynthesis. The fractures of the hamate are usually diagnosed late, and the most recommended treatment is removal of the fragment, although it cannot be deduced from this study. Copyright © 2014 SECOT. Published by Elsevier Espana. All rights reserved.

  1. Colles Fracture

    OpenAIRE

    Sánchez León, Belisario; Facultad de Medicina, Universidad Nacional Mayor de San Marcos, Lima, Perú

    2014-01-01

    Our expertise is the study of more than 2,000 cases of Colles' fractures. Colles name should in this case to synthesize the type of fractures of the lower end of the radius. There have been various proposed classifications according to the different fracture lines can be demonstrated radiologically in the region of the wrist. We believe that these ratings should only be retained if the concept of the articular fracture or not in the classical sense, since it has great value in the functional ...

  2. Fracture mechanics of PGX graphite

    Energy Technology Data Exchange (ETDEWEB)

    Ho, F.H.; Vollman, R.E.; Cull, A.D.

    1981-03-01

    Fracture mechanics tests were performed on grade PGX graphite. A compact tension specimen configuration which yields consistent values of the opening mode critical stress intensity factor K/sub IC/, was designed. For the calculation of the fracture toughness and crack growth rate the concept of the effective crack length is used. It corresponds to the crack length of a machined notched specimen with the same compliance. Fracture toughness testing was performed in two environments, air and helium, both at room temperature. The critical stress intensity factor, K/sub IC/, is calculated based on the maximum load and the effective crack length. The fatigue crack growth test was performed in air only. A break-in period was observed for the machined notch to develop into a naturally occurring crack path. Half of the fatigue life was spent in this period.

  3. Economic viability of geriatric hip fracture centers.

    Science.gov (United States)

    Clement, R Carter; Ahn, Jaimo; Mehta, Samir; Bernstein, Joseph

    2013-12-01

    Management of geriatric hip fractures in a protocol-driven center can improve outcomes and reduce costs. Nonetheless, this approach has not spread as broadly as the effectiveness data would imply. One possible explanation is that operating such a center is not perceived as financially worthwhile. To assess the economic viability of dedicated hip fracture centers, the authors built a financial model to estimate profit as a function of costs, reimbursement, and patient volume in 3 settings: an average US hip fracture program, a highly efficient center, and an academic hospital without a specific hip fracture program. Results were tested with sensitivity analysis. A local market analysis was conducted to assess the feasibility of supporting profitable hip fracture centers. The results demonstrate that hip fracture treatment only becomes profitable when the annual caseload exceeds approximately 72, assuming costs characteristic of a typical US hip fracture program. The threshold of profitability is 49 cases per year for high-efficiency hip fracture centers and 151 for the urban academic hospital under review. The largest determinant of profit is reimbursement, followed by costs and volume. In the authors’ home market, 168 hospitals offer hip fracture care, yet 85% fall below the 72-case threshold. Hip fracture centers can be highly profitable through low costs and, especially, high revenues. However, most hospitals likely lose money by offering hip fracture care due to inadequate volume. Thus, both large and small facilities would benefit financially from the consolidation of hip fracture care at dedicated hip fracture centers. Typical US cities have adequate volume to support several such centers.

  4. Low-trauma fractures indicate increased risk of hip fracture in frail older people.

    Science.gov (United States)

    Chen, Jian Sheng; Cameron, Ian D; Simpson, Judy M; Seibel, Markus J; March, Lyn M; Cumming, Robert G; Lord, Stephen R; Sambrook, Philip N

    2011-02-01

    This study aims to investigate the risk of subsequent fractures after low-trauma fracture in frail older people. A total of 1412 elderly residents (mean age 86.2 years, SD 7.0 years, female 77%) were recruited from aged care facilities in Australia. Residents were assessed and then followed for any fracture for 2 years and hip fractures for at least 5 years. Residents with and without a newly acquired fracture in the first 2 years were compared for risk of subsequent hip fracture. Residents with a nonhip fracture in the first 2 years had an increased risk of subsequent hip fracture for about 2.5 years, whereas those with a hip fracture had a similar risk over the whole period compared with those with no fracture. During these 2.5 years, 60, 28, and 6 subsequent hip fractures occurred in the nonfracture group (n = 953), the nonhip fracture group (n = 194), and the hip fracture group (n = 101), respectively, resulting in the probability of subsequent hip fracture of 8.0%, 19.9%, and 10.4%, respectively. Compared with the nonfracture group, the hazard ratio (HR) was 2.82 [95% confidence interval (CI) 1.73-4.59; p < .001] for the nonhip fracture group and 1.48 (95% CI 0.63-3.49, p = .37) for the hip fracture group after adjusting for age, sex, residence type, calcaneal broadband ultrasound attenuation, fracture history, weight, lower leg length, immobility, cognitive function, and medications. Frail institutionalized older people with newly acquired fractures are at increased risk of subsequent hip fracture for the next few years. Accordingly, despite their advanced age, they are a high-priority target group to investigate interventions that might reduce the risk of hip fracture.

  5. Fracture Mechanics

    CERN Document Server

    Zehnder, Alan T

    2012-01-01

    Fracture mechanics is a vast and growing field. This book develops the basic elements needed for both fracture research and engineering practice. The emphasis is on continuum mechanics models for energy flows and crack-tip stress- and deformation fields in elastic and elastic-plastic materials. In addition to a brief discussion of computational fracture methods, the text includes practical sections on fracture criteria, fracture toughness testing, and methods for measuring stress intensity factors and energy release rates. Class-tested at Cornell, this book is designed for students, researchers and practitioners interested in understanding and contributing to a diverse and vital field of knowledge. Alan Zehnder joined the faculty at Cornell University in 1988. Since then he has served in a number of leadership roles including Chair of the Department of Theoretical and Applied Mechanics, and Director of the Sibley School of Mechanical and Aerospace Engineering.  He teaches applied mechanics and his research t...

  6. Hip fracture in hospitalized medical patients

    Directory of Open Access Journals (Sweden)

    Zapatero Antonio

    2013-01-01

    Full Text Available Abstract Background The aim of the present study is to analyze the incidence of hip fracture as a complication of admissions to internal medicine units in Spain. Methods We analyzed the clinical data of 2,134,363 adults who had been admitted to internal medicine wards. The main outcome was a diagnosis of hip fracture during hospitalization. Outcome measures included rates of in-hospital fractures, length of stay and cost. Results A total of 1127 (0.057% admittances were coded with an in-hospital hip fracture. In hospital mortality rate was 27.9% vs 9.4%; p  Conclusions In-hospital hip fracture notably increased mortality during hospitalization, doubling the mean length of stay and mean cost of admission. These are reasons enough to stress the importance of designing and applying multidisciplinary plans focused on reducing the incidence of hip fractures in hospitalized patients.

  7. Fracture imaging with converted elastic waves

    Energy Technology Data Exchange (ETDEWEB)

    Nihei, K.T.; Nakagawa, S.; Myer, L.R.

    2001-05-29

    This paper examines the seismic signatures of discrete, finite-length fractures, and outlines an approach for elastic, prestack reverse-time imaging of discrete fractures. The results of this study highlight the importance of incorporating fracture-generated P-S converted waves into the imaging method, and presents an alternate imaging condition that can be used in elastic reverse-time imaging when a direct wave is recorded (e.g., for crosswell and VSP acquisition geometries).

  8. Recent trends in fracture and damage mechanics

    CERN Document Server

    Zybell, Lutz

    2016-01-01

    This book covers a wide range of topics in fracture and damage mechanics. It presents historical perspectives as well as recent innovative developments, presented by peer reviewed contributions from internationally acknowledged authors.  The volume deals with the modeling of fracture and damage in smart materials, current industrial applications of fracture mechanics, and it explores advances in fracture testing methods. In addition, readers will discover trends in the field of local approach to fracture and approaches using analytical mechanics. Scholars in the fields of materials science, engineering and computational science will value this volume which is dedicated to Meinhard Kuna on the occasion of his 65th birthday in 2015. This book incorporates the proceedings of an international symposium that was organized to honor Meinhard Kuna’s contributions to the field of theoretical and applied fracture and damage mechanics.

  9. Direct tension and fracture resistance curves of ultra high performance marine composite materials

    Institute of Scientific and Technical Information of China (English)

    WU Xiang-guo; HAN Sang-mook

    2008-01-01

    Fracture behavior is one of the most important, yet still little understood properties of ultra-high performance cementitious composites (UHPCC), a new marine structural engineering material.Research on the fracture and direct tension behavior of UHPCC was carried out. The constitution law of UHPCC was divided into three phases: pre-partial debonding, partial debonding, and pullout phases. A direct tension constitution law was constructed based on the proposed fiber reinforcing parameter as a function of fiber volume fraction, fiber diameter and length, and fiber bonding strength. With the definition of linear crack shape, the energy release rate of UHPCC was derived and the R-curve equation was calculated from this. Loading tests of UHPCC using a three-point bending beam with an initial notch were carried out. The predictions from the proposed R-curve were in good agreement with the test results,indicating that the proposed R-curve accurately describes the fracture resistance of UHPCC. Introductionof a fiber reinforcement parameter bridges the fracture property R-curve and micro-composites mechanics parameters together. This has laid the foundation for further research into fracture properties based on micro-mechanics. The proposed tension constitution law and R-curve can be references for future UHPCC fracture evaluation.

  10. a Fractal Network Model for Fractured Porous Media

    Science.gov (United States)

    Xu, Peng; Li, Cuihong; Qiu, Shuxia; Sasmito, Agus Pulung

    2016-04-01

    The transport properties and mechanisms of fractured porous media are very important for oil and gas reservoir engineering, hydraulics, environmental science, chemical engineering, etc. In this paper, a fractal dual-porosity model is developed to estimate the equivalent hydraulic properties of fractured porous media, where a fractal tree-like network model is used to characterize the fracture system according to its fractal scaling laws and topological structures. The analytical expressions for the effective permeability of fracture system and fractured porous media, tortuosity, fracture density and fraction are derived. The proposed fractal model has been validated by comparisons with available experimental data and numerical simulation. It has been shown that fractal dimensions for fracture length and aperture have significant effect on the equivalent hydraulic properties of fractured porous media. The effective permeability of fracture system can be increased with the increase of fractal dimensions for fracture length and aperture, while it can be remarkably lowered by introducing tortuosity at large branching angle. Also, a scaling law between the fracture density and fractal dimension for fracture length has been found, where the scaling exponent depends on the fracture number. The present fractal dual-porosity model may shed light on the transport physics of fractured porous media and provide theoretical basis for oil and gas exploitation, underground water, nuclear waste disposal and geothermal energy extraction as well as chemical engineering, etc.

  11. Total hip arthroplasty for the treatment of old femoral neck fractures with lower limb length discrepancy%全髋关节置换治疗伴有下肢短缩的陈旧性股骨颈骨折☆

    Institute of Scientific and Technical Information of China (English)

    魏人前; 曹兴海; 涂大华

    2012-01-01

    BACKGROUND: Most femoral neck fracture patients with lower limb length discrepancy have experienced long-term traction orfailure internal fixation, the hip has severe osteoporosis, soft tissues around the hip joint and joint capsules contracture oravascular necrosis as well as the lower limb length discrepancy, so the clinical treatment is difficult.OBJECTIVE: To explore the clinical effect of total hip arthroplasty for treatment of old femoral neck fracture complicated with limplength discrepancy.METHODS: Thirty-five cases of old femoral neck fractures with lower limb length discrepancy were treated with total hiparthroplasty. Skeletal traction on the femoral condyle and the X-ray measurement of both lower extremities and pelvis wereprepared preoperatively, it was done to anticipate for the level of femoral neck osteotomy and the level of loosing up tissuearound hip joint, as well as to adjust the length of the prosthesis head and neck in order to maintain the length of the limbs duringsurgery.RESULTS AND CONCLUSION: Results of the 6 patients with shortened limb ranging 3.0-4.0 cm preoperartively, only 1 casehad limb length discrepancy in 1 cm after surgery, as for the rest 5 cases and 29 patients with shortened limb ranging 1 to 2 cmpreoperatively, none limb had been shortened postoperatively compared with its contralateral limb. According to Harris scoresystem, the mean preoperative Harris score was significantly improved after 1 year postoperatively (P < 0.05). Total hipreplacement can recover hip function rapidly and steady with a high good rate and satisfactory short term effect. Therefore,total hip arthroplasty is a very important and an effective treatment method for old femoral neck fracture with limp lengthdiscrepancy.%背景:由于多数伴有下肢短缩的陈旧性股骨颈骨折患者经历过长期牵引或失败的内固定手术,髋部已严重骨质疏松,髋关节周围软组织及关节囊挛缩或股骨头缺血坏死,下肢短缩,临床治疗

  12. Fracture mechanics

    CERN Document Server

    Perez, Nestor

    2017-01-01

    The second edition of this textbook includes a refined presentation of concepts in each chapter, additional examples; new problems and sections, such as conformal mapping and mechanical behavior of wood; while retaining all the features of the original book. The material included in this book is based upon the development of analytical and numerical procedures pertinent to particular fields of linear elastic fracture mechanics (LEFM) and plastic fracture mechanics (PFM), including mixed-mode-loading interaction. The mathematical approach undertaken herein is coupled with a brief review of several fracture theories available in cited references, along with many color images and figures. Dynamic fracture mechanics is included through the field of fatigue and Charpy impact testing. Explains computational and engineering approaches for solving crack-related problems using straightforward mathematics that facilitate comprehension of the physical meaning of crack growth processes; Expands computational understandin...

  13. Fracture mechanics

    Science.gov (United States)

    Shannon, John L., Jr.

    1986-01-01

    The application of fracture mechanics to the design of ceramic structures will require the precise measurement of crack growth and fracture resistance of these materials over their entire range of anticipated service temperatures and standardized test methods for making such measurements. The development of a standard test for measuring the plane strain fracture toughness is sought. Stress intensity factor coefficients were determined for three varieties of chevron-notch specimens, and fracture toughness measurements were made on silicon nitrides, silicon carbides, and aluminum oxides to assess the performance of each specimen variety. It was determined that silicon nitride and silicon carbides have flat crack growth resistance curves, but aluminum oxide does not. Additionally, batch-to-batch differences were noticed for the aluminum oxide. Experiments are continuing to explain the rising crack growth resistance and batch-to-batch variations for the aluminum oxide.

  14. Current concepts in pediatric femur fracture treatment.

    Science.gov (United States)

    Kanlic, Enes; Cruz, Miguel

    2007-12-01

    Femoral neck fractures require urgent evacuation of intracapsular hematoma, anatomic reduction, and secure fixation with screws and cast immobilization. Extracapsular trochanteric and subtrochanteric fractures are best treated by fixed angle devices (locked plates or dynamic screw and side plate). "Length stable" low energy shaft fractures with minimal displacement or fractures are treated operatively. Transverse or short oblique shaft fractures in patients fractures. Children > 12 years have less risk of vascular disturbance to the proximal physis, and should have lateral transtrochanateric entry locked rigid nails. Fractures with severe soft tissue injuries could be temporized with external fixation. Distal physis and epiphyseal injuries require anatomical reduction and smooth wires and/or screw fixation (placed in such a way as to minimize further damage to the physis) and need to be augmented with a brace. Leg-length discrepancy is not a significant clinical problem in operatively treated patients. We recommend hardware removal after complete fracture healing, usually in 6 to 12 months. Implants left in the growing child could become buried deep inside of the bone, or cause "periprosthetic" fractures and/or eventually impede adult reconstruction. Minimal risks are reported for hardware removal in healthy patients with healed fractures (4 cortices bridged).

  15. Periprosthetic Occult Fractures of the Acetabulum Occur Frequently During Primary THA.

    Science.gov (United States)

    Hasegawa, Kazuhiro; Kabata, Tamon; Kajino, Yoshitomo; Inoue, Daisuke; Tsuchiya, Hiroyuki

    2017-02-01

    Periprosthetic fractures of the acetabulum occurring during primary THA are rare. Periprosthetic occult fractures are defined as those not identified by the surgeon during the procedure which might be missed on a routine postoperative radiograph. However, it is unclear how frequently these fractures occur and whether their presence affects functional recovery. In this study, using routine CT scans that were obtained as part of another primary hip arthroplasty study protocol, we retrospectively assessed (1) the prevalence of occult fractures of the acetabulum occurring during primary THA, (2) the location of occult fractures of the acetabulum during THA, and (3) risk factors contributing to such occult fractures. Between 2004 and 2013, our institute performed 585 primary THAs (cementless or hybrid) in 494 patients with DICOM pre- and postoperative CT; during the period in question, all patients undergoing THA underwent CT before and after surgery. Preoperative CT images were taken as part of a CT-based three-dimensional templating software and navigation system. Postoperative CT images were taken an average of 1 week after surgery as part of a different protocol to evaluate cup position, restoration of leg length and offset, volume of postoperative hematoma to assess anticoagulation effects after THA, and fractures that were not found on routine postoperative radiographs (which we defined as occult fractures). Patients with a history of prior pelvic osteotomy, trauma, and infection were excluded (88 patients/99 hips); 406 patients (102 males and 304 females; 486 hips) form the basis of this report. The mean age of the patients was 60 ± 11 years, with a mean BMI of 23 ± 4 kg/m(2). The mean followup of the patients with periprosthetic fracture of the acetabulum was 58 ± 28 months (range, 12-131 months). Potential risk factors for occult acetabular fracture including age, sex, BMI, preoperative diagnosis, additional dome screw fixation, composition and size of each

  16. Characterisation of hydraulically-active fractures in a fractured ...

    African Journals Online (AJOL)

    2015-01-07

    Jan 7, 2015 ... maximum depth of the tunnel is 90–100 m from the peak of a mountain located above the .... g is the gravity acceleration l is the length of the test ..... process and is a hydraulically-active fracture conducting ground- water flow.

  17. Meshless Animation of Fracturing Solids

    Science.gov (United States)

    Pauly, Mark; Keiser, Richard; Adams, Bart; Dutré, Philip; Gross, Markus; Guibas, Leonidas J.

    2010-01-01

    We present a new meshless animation framework for elastic and plastic materials that fracture. Central to our method is a highly dynamic surface and volume sampling method that supports arbitrary crack initiation, propagation, and termination, while avoiding many of the stability problems of traditional mesh-based techniques. We explicitly model advancing crack fronts and associated fracture surfaces embedded in the simulation volume. When cutting through the material, crack fronts directly affect the coupling between simulation nodes, requiring a dynamic adaptation of the nodal shape functions. We show how local visibility tests and dynamic caching lead to an efficient implementation of these effects based on point collocation. Complex fracture patterns of interacting and branching cracks are handled using a small set of topological operations for splitting, merging, and terminating crack fronts. This allows continuous propagation of cracks with highly detailed fracture surfaces, independent of the spatial resolution of the simulation nodes, and provides effective mechanisms for controlling fracture paths. We demonstrate our method for a wide range of materials, from stiff elastic to highly plastic objects that exhibit brittle and/or ductile fracture. PMID:21165160

  18. On the scale-invariance of fractures and fracture patterns in the Transscandinavian Igneous Belt, Southeast Sweden

    Science.gov (United States)

    Krumbholz, M.; Burchardt, S.; Tanner, D. C.; Koyi, H.

    2012-04-01

    Fracture dimensions and their spatial distribution are of primary importance in many fields of applied geology, e.g. they determine the quality of sites for the long-term storage of hazardous waste and fractured reservoirs for e.g. hydrocarbons, CO2 sequestration, and geothermal energy. Unfortunately, the observation of fracture systems is commonly limited by the outcrop size or the resolution of the measuring method. Fractures and fracture properties are often assumed to be scale-invariant, albeit within a certain range. Therefore, knowing the fractal dimension of fracture properties allows conclusions to be drawn from one particular scale to another. We investigated fracture trace lengths and patterns at map-, outcrop- and handspecimen scale, covering a large area in the Transscandinavian Igneous Belt. The dataset comprises 11 fracture maps at three different scales containing 8641 fracture trace lengths. Analysis of the fracture trace lengths was carried out using cumulative frequency distributions, while the fracture patterns were analysed with the standard box-counting technique. Combining the three analysed scales, our results indicate that the fracture trace lengths can be considered to be scale-invariant with a fractal dimension of about 1.8. In contrast, the fractal dimension at one particular scale could not be determined, probably due to censoring and truncation effects. Analyses with the box-counting method show that the fracture patterns, in contrast to fracture trace lengths, are not scale-invariant. The box-counting dimension increases with increasing scale. It is a measure of the complexity and maturity of a fracture system, which increases with scale. Consequently, the complexity of fracture pattern is scale-variant.

  19. Factors Affecting Postsurgery Hip Fracture Recovery

    Directory of Open Access Journals (Sweden)

    Sydney Wallace

    2014-12-01

    Full Text Available After hip fracture surgery, patients seldom return to their prefracture functional state and there is a 43% rate of mortality and institutionalisation of postsurgery hip fracture patients. A systematic literature review was conducted to identify preoperative, perioperative, postoperative, and psychosocial factors that may hinder postsurgery hip fracture patients from returning to previous functionality. Factors that were identified as being associated with postsurgical outcomes were age, muscle strength, prefracture living arrangements, number of daily medications taken, oxygen levels, fracture type and location, haemoglobin (Hb level, wait time prior to surgery, length of hospital stay (LOS, and dementia or depression.

  20. Experimental study on fracture properties of Waste fiber recycled concrete

    Directory of Open Access Journals (Sweden)

    Zhou Jing Hai

    2016-01-01

    Full Text Available In order to study the influence of the replacement ratio of recycled aggregate and the volume of waste fiber on the fracture performance of concrete, the three-point bending test is carried out on the waste fiber recycled concrete precast beams. Calculate the waste recycled fiber concrete fracture parameters according to the double-K fracture model. The results show that the fracture indexes of recycled fiber are related to the recycled aggregate replacement ratio and the volume content of waste fiber. The larger the replacement rate of recycled aggregate is, the smaller the fracture indexes of the specimens are. The volume content of waste fiber is 0.12%, which has the most significant effect on the fracture performance. The study shows that waste fiber can improve the fracture properties of recycled aggregate concrete.

  1. Simulation of complex fracture networks influenced by natural fractures in shale gas reservoir

    Directory of Open Access Journals (Sweden)

    Zhao Jinzhou

    2014-10-01

    Full Text Available When hydraulic fractures intersect with natural fractures, the geometry and complexity of a fracture network are determined by the initiation and propagation pattern which is affected by a number of factors. Based on the fracture mechanics, the criterion for initiation and propagation of a fracture was introduced to analyze the tendency of a propagating angle and factors affecting propagating pressure. On this basis, a mathematic model with a complex fracture network was established to investigate how the fracture network form changes with different parameters, including rock mechanics, in-situ stress distribution, fracture properties, and frac treatment parameters. The solving process of this model was accelerated by classifying the calculation nodes on the extending direction of the fracture by equal pressure gradients, and solving the geometrical parameters prior to the iteration fitting flow distribution. With the initiation and propagation criterion as the bases for the propagation of branch fractures, this method decreased the iteration times through eliminating the fitting of the fracture length in conventional 3D fracture simulation. The simulation results indicated that the formation with abundant natural fractures and smaller in-situ stress difference is sufficient conditions for fracture network development. If the pressure in the hydraulic fractures can be kept at a high level by temporary sealing or diversion, the branch fractures will propagate further with minor curvature radius, thus enlarging the reservoir stimulation area. The simulated shape of fracture network can be well matched with the field microseismic mapping in data point range and distribution density, validating the accuracy of this model.

  2. Update on the efficacy, safety, and adherence to treatment of full length parathyroid hormone, PTH (1-84, in the treatment of postmenopausal osteoporosis

    Directory of Open Access Journals (Sweden)

    Luca Pietrogrande

    2009-11-01

    Full Text Available Luca PietrograndeDipartimento di Medicina Chirurgia e Odontoiatria Polo San Paolo, Università degli Studi di Milano, Milan, ItalyAbstract: Full length (1-84 parathyroid hormone (PTH was introduced in Europe as a treatment for postmenopausal osteoporosis in 2006. The efficacy of PTH (1-84 in the prevention of vertebral fractures is very high, and is similar to that of teriparatide. Its action in the prevention of femoral fractures has yet to be fully demonstrated, but the incidence of such fractures in trials was very low, and a decrease in nonvertebral fractures was seen in high-risk patients. The effect on bone mineral density (BMD was clearly demonstrated in the spine and also in the hip. The effects on BMD were evident and increased progressively with treatment until 36 months. After its discontinuation there was a clear decrease in BMD if no antiresorptive treatment was initiated. Increases in bone volumetric density and bone volume in trabecular sites were also reported. Moreover, a bone volume increase was detected in cortical sites. Hypercalcemia and hypercalciuria are frequent consequences of PTH treatment, but rarely have clinical effects and are usually well controlled by reducing calcium and vitamin D supplementation.Keywords: PTH (1-84, full-length parathyroid hormone, osteoporosis treatment

  3. Galeazzi fracture.

    Science.gov (United States)

    Atesok, Kivanc I; Jupiter, Jesse B; Weiss, Arnold-Peter C

    2011-10-01

    Galeazzi fracture is a fracture of the radial diaphysis with disruption at the distal radioulnar joint (DRUJ). Typically, the mechanism of injury is forceful axial loading and torsion of the forearm. Diagnosis is established on radiographic evaluation. Underdiagnosis is common because disruption of the ligamentous restraints of the DRUJ may be overlooked. Nonsurgical management with anatomic reduction and immobilization in a long-arm cast has been successful in children. In adults, nonsurgical treatment typically fails because of deforming forces acting on the distal radius and DRUJ. Open reduction and internal fixation is the preferred surgical option. Anatomic reduction and rigid fixation should be followed by intraoperative assessment of the DRUJ. Further intraoperative interventions are based on the reducibility and postreduction stability of the DRUJ. Misdiagnosis or inadequate management of Galeazzi fracture may result in disabling complications, such as DRUJ instability, malunion, limited forearm range of motion, chronic wrist pain, and osteoarthritis.

  4. Fracture Blisters

    Directory of Open Access Journals (Sweden)

    Uebbing, Claire M

    2011-02-01

    Full Text Available Fracture blisters are a relatively uncommon complication of fractures in locations of the body, such as the ankle, wrist elbow and foot, where skin adheres tightly to bone with little subcutaneous fat cushioning. The blister that results resembles that of a second degree burn.These blisters significantly alter treatment, making it difficult to splint or cast and often overlying ideal surgical incision sites. Review of the literature reveals no consensus on management; however, most authors agree on early treatment prior to blister formation or delay until blister resolution before attempting surgical correction or stabilization. [West J Emerg Med. 2011;12(1;131-133.

  5. A Coupled Mean Field / Gurson-Tvergaard Micromechanical Model For Ductile Fracture In Multiphase Materials With Large Volume Fraction of Voids

    Science.gov (United States)

    Van Hoof, Thibaut; Piérard, Olivier; Lani, Frédéric

    2007-04-01

    In the framework of the European project PROHIPP (New design and manufacturing processes for high pressure fluid power product — NMP 2-CT-2004-50546), CENAERO develops a library of constitutive models used to predict the mechanical response of a family of cast iron. The present contribution focuses on one particular microstructure, corresponding to a ferrite matrix containing spheroidal graphite and isolated inclusions of pearlite. An incremental mean field homogenisation scheme such as the one developed by Doghri and Ouaar is used. In the present application, the ferrite matrix is described by a Gurson type constitutive law (porous plasticity) while the pearlite inclusions are assumed to obey the classical isotropic J2 plasticity. The predictions of the micromechanical model are compared to the results of Finite Element simulations performed on three-dimensional representative volume elements (RVEs).

  6. Distribution of bone density and cortical thickness in the proximal femur and their association with hip fracture in postmenopausal women: a quantitative computed tomography study.

    Science.gov (United States)

    Yang, L; Udall, W J M; McCloskey, E V; Eastell, R

    2014-01-01

    The quantitative computed tomography (QCT) scans in an individually matched case-control study of women with hip fracture were analysed. There were widespread deficits in the femoral volumetric bone mineral density (vBMD) and cortical thickness of cases, and cortical vBMD and thickness discriminated hip fracture independently of BMD by dual-energy X-ray absorptiometry (DXA). Acknowledging the limitations of QCT associated with partial volume effects, we used QCT in an individually matched case-control study of women with hip fracture to better understand its structural basis. Fifty postmenopausal women (55-89 years) who had sustained hip fractures due to low-energy trauma underwent QCT scans of the contralateral hip within 3 months of the fracture. For each case, postmenopausal women, matched by age (±5 years), weight (±5 kg) and height (±5 cm), were recruited as controls. We quantified cortical, trabecular and integral vBMD and apparent cortical thickness (AppCtTh) in four quadrants of cross-sections along the length of the femoral head (FH), femoral neck (FN), intertrochanter and trochanter and examined their association with hip fracture. Women with hip or intracapsular (IC) fracture had significantly (p hip and IC fractures independent of hip areal BMD (aBMD). The combination of AppCtTh and trabecular or integral vBMD discriminated hip fracture, whereas the combination of FH and FN AppCtTh discriminated IC fracture significantly (p hip aBMD. Deficits in vBMD and AppCtTh in cases were widespread in the proximal femur, and cortical vBMD and AppCtTh discriminated hip fracture independently of aBMD by DXA.

  7. Type IIA Monteggia Fracture Dislocation with Ipsilateral Distal Radius Fracture in Adult – A Rare Association

    Science.gov (United States)

    James, Boblee

    2016-01-01

    Monteggia fracture constitutes about 5-10% of the forearm fractures. Monteggia fracture by definition is proximal ulnar fracture with disruption of proximal radioulnar joint. Bado classified Monteggia fracture dislocation into four types and Jupiter subclassified type II Bado’s fractures into four types. The associated injury in the form of distal radial fractures and distal humerus fractures are rare though many cases of distal radial physeal injuries have been reported in paediatric population. Hereby we report a rare association of type IIA Monteggia fracture dislocation with ipsilateral distal radius fracture in an adult patient. This case report also highlights on proper examination and full length radiographs of forearm to avoid missing injury at wrist in cases of elbow injuries. Management of such complex injuries included open reduction and internal fixation of olecronon fracture, distal radius fracture and radial head resection. Functional outcome at six months was good at wrist whereas at elbow, stiffness was a major concern with elbow range of movement from 40°-110°. PMID:27656518

  8. Economic Influence of Hydraulic Fracturing Parameters on Horizontal Wells in Shale Gas Bed%压裂参数对水平页岩气井经济效果的影响

    Institute of Scientific and Technical Information of China (English)

    李庆辉; 陈勉; 金衍; 赵飞; 姜海龙

    2013-01-01

    采用产能模拟方法将净现值和内部收益率作为评价指标,对不同压裂参数下页岩气井的经济效果进行评价,研究不同压裂间距、压裂级数和加砂量对页岩气井经济效果的影响,结果表明:压裂的间距、级数和加砂量对开发的效果影响显著;压裂间距并非越长越好,当压裂级数和加砂量较少时,短水平段密集压裂反而更易获利;压裂级数通过改变单级压裂的控制体积和支撑剂密度影响产能和收益情况;加砂量通过支撑剂密度改变渗流通道环境,影响最终产量,存在最优铺砂密度并与前2项因素共同影响最终经济效果.实际钻、完井方案制订时,应考虑上述3种工程因素的综合影响,制订最优开发方案.%Economic effect of shale gas wells is evaluated under different fracturing parameters and the influence of fracturing well space, fracturing stages and proppant volume on fracturing effect is studied by adopting productivity simulation which regards NPV and IROR as evaluation indicators. The results of the study shows that the influence of fracturing well space, fracturing stages and proppant volume on fracturing effect is obvious; it' s not right that the longer the fracturing well space, the better the fracturing effect, however, when fracturing stages and sand volume are small, dense fracturing with short horizontal section length can even get a better effect; fracturing stages can influence productivity and economic effect by changing the controlled volume of individual stage fracturing and proppant density; sand volume changes flow channel environment by proppant, influences productivity, has an optimal density and combined with the 2 factors above influences economic effect. The preparation of drilling and completion program should consider the 3 factors mentioned above and optimal FDP should be prepared.

  9. A Semi-Analytical Model for Heat and Mass Transfer in Geothermal Reservoirs to Estimate Fracture Surface-Area-to-Volume Ratios and Thermal Breakthrough using Thermally-Decaying and Diffusing Tracers

    Science.gov (United States)

    Reimus, P. W.

    2010-12-01

    according to the rate constant kd = A*exp(-Ea/RT) , where kd = decay rate constant (1/s), R = ideal gas constant (1.987 cal/mol-K), and T = absolute temperature (K). It is shown that there are relatively narrow ranges of A and Ea that will result in readily interpretable tracer responses for any given combination of ambient reservoir temperature and working fluid residence time in a reservoir. The combined model was also used to simulate the responses of conservative tracers with different diffusion coefficients as a way of estimating fracture surface-area-to-volume ratios (SA/V) in multi-well EGS systems. This method takes advantage of the fact that the differences in breakthrough curves of tracers with different matrix diffusion coefficients are a function of SA/V. The model accounts for differences in diffusion coefficients as a function of temperature so that tracer responses obtained at different times can be used to obtain consistent estimates of SA/V as the reservoir cools down. Some single-well applications of this approach are simulated with a numerical model to demonstrate the potential to evaluate the effectiveness of EGS stimulations before a second well is drilled.

  10. Hand Fractures

    Science.gov (United States)

    ... Z Videos Infographics Symptom Picker Anatomy Bones Joints Muscles Nerves Vessels Tendons About Hand Surgery What is a Hand Surgeon? What is ... serve as a framework. This framework supports the muscles that make the wrist ... When one of these hand bones is broken (fractured), it can prevent you ...

  11. Fracture source

    Directory of Open Access Journals (Sweden)

    2003-07-01

    Full Text Available The fracture properties of many different types of fibers are covered in a timely new book that will prove to be a tremendous source of information and references for researchers in the wide and diverse field of fibers and composites, says Bill Clegg.

  12. Rib Fractures

    Science.gov (United States)

    ... Commentary Recent News Scientists Working on Solar-Powered Prosthetic Limbs Exercise a Great Prescription to Help Older Hearts Bavencio Approved for Rare Skin Cancer Older Mothers May Raise Better-Behaved Kids, Study ... or a collapsed lung (pneumothorax—see Traumatic Pneumothorax ). An injury that fractures the lower ribs sometimes also damages the liver (see Liver ...

  13. [Thoracolumbar fractures].

    Science.gov (United States)

    Freslon, M; Bouaka, D; Coipeau, P; Defossez, G; Leclercq, N; Nebout, J; Marteau, E; Poilbout, N; Prebet, R

    2008-06-01

    Thoracolumbar fractures are frequent and the functional outcomes are sometimes severe. This multicentric study, including five medical centers, was performed to evaluate the long-term outcomes of the patients. One hundred and thirty six patients with thoracolumbar fracture (T11 to L2) was evaluated with a minimal follow-up of two years. Every one had a clinical exam with a score of Oswestry and an X-Ray study (before and after treatment and at revision). Most of them presented compression fractures, the most often at L1 level. On X-rays, a gain was noted on the vertebral kyphosis immediately after surgery, but there is a loss of correction over time whatever the treatment. The clinical outcomes for the patients were great, with an Oswestry average score of 6,4. A correlation was noted between this functional score and vertebral kyphosis. So, an anterior column strengthening (isolated or performed during the surgery) could improve these functional outcomes. Moreover, the Thoraco Lumbar Injury Severity Score (TLISS) seems to be a simple organigram to determine the most appropriate treatment of these fractures, with particular attention to the distraction mechanism or posterior ligamentous complex lesions. However, RMI before surgery is necessary to evaluate these lesions.

  14. Estimation of genome length

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The genome length is a fundamental feature of a species. This note outlined the general concept and estimation method of the physical and genetic length. Some formulae for estimating the genetic length were derived in detail. As examples, the genome genetic length of Pinus pinaster Ait. and the genetic length of chromosome Ⅵ of Oryza sativa L. were estimated from partial linkage data.

  15. Prediction of Flow and Solute Transport in Fractured Media: Comparison of Metrics to Describe Effects of Rough Surfaces

    Science.gov (United States)

    Slottke, D.; Ketcham, R. A.; Sharp, J. M.

    2008-05-01

    Fractures dominate fluid flow and transport of solutes when they are open and connected. The prediction of flow through fractured media has implications for development of water resources, petroleum reservoir exploitation, contamination and remediation assessment, and site evaluation for waste repositories. Assessing the impact of surface roughness on fluid flow and solute transport through fractured media from samples on the order of 100 cm2 assumes the existence of a relationship between fracture morphology and discharge that is scale invariant or at least smoothly transformable. Although some studies assume that the length scale at which surface roughness significantly contributes to the discharge through a fracture falls within the size of a typical hand sample, there is a dearth of empirical data supporting an extension of the relationships found at small scales to larger samples. Furthermore, an appropriate metric to describe a fracture volume accurately must be chosen. We compile data from physical flow tests and numerical modeling of two discrete natural fractures of different scales in rhyolitc tuff. The University of Texas HRXCT facility provided computed tomography representations of the fractures that allow analysis of surface roughness and aperture statistics at 0.25mm grid resolution, which form the basis for transmissivity field inputs to numerical models. We show that although a small (10cm2) representative surface can describe roughness, aperture fields are not so well behaved. We compare physical flow test results, modeled flow, and analytical solutions of the cubic law using various methods of assigning a meaningful aperture to illustrate the challenges of accurate modeling of fracture flow without a priori flow information. While a geometric mean aperture of the entire aperture field closely approximates the hydraulic aperture, an arbitrary profile mean aperture has little utility for predictive purposes.

  16. Traumatic sternal fracture: Incidence, causes and CT features

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hyo Weon; Kim, Young Tong; Jou, Sung Shick; Han, Jong Kyu; Bae, Won Kyung [Dept. of Radiology, Soonchunhyang University College of Medicine, Cheonan Hospital, Cheonan (Korea, Republic of)

    2015-05-15

    To evaluate the incidence of sternal fracture due to trauma, the CT features of sternal fractures, and the hospitalization period. The medical records and CT images of 755 patients who suffered trauma from January 2012 to August 2013 were analyzed retrospectively. We compared the incidence of sternal fracture due to various traumatic causes. We evaluated the location and shape of the sternal fracture on CT scans and the relationship between a sternal fracture and the hospitalization period. The incidence of sternal fracture was 9.27% (70/755) in all patients; 11.7% (53/453) due to a traffic accident (TA), and 5.63% (17/302) due to other causes. TA was the most frequent cause (75.71%) of a sternal fracture, fracture incidences after a TA differed by traumatic cause (p < 0.05). Among sternal fractures, the body was the most commonly involved (68.57%), one wall was limited (32.85%), and anteroposterior length increased (7.14%). Body fractures involving two or more segments included 33.33% of the cases. The hospitalization period was not related with sternal fracture (p = 0.30). Fracture was more frequent after a TA than due to other causes. Fracture incidences after a TA depended on the traumatic causes. Involvement of two or more segments and one wall-limitation were common among sternal fractures. Sternal fractures occurred even in slightly injured patients.

  17. Natural fracture characterization using passive seismic illumination

    Energy Technology Data Exchange (ETDEWEB)

    Nihei, K.T.

    2003-01-08

    The presence of natural fractures in reservoir rock can significantly enhance gas production, especially in tight gas formations. Any general knowledge of the existence, location, orientation, spatial density, and connectivity of natural fractures, as well as general reservoir structure, that can be obtained prior to active seismic acquisition and drilling can be exploited to identify key areas for subsequent higher resolution active seismic imaging. Current practices for estimating fracture properties before the acquisition of surface seismic data are usually based on the assumed geology and tectonics of the region, and empirical or fracture mechanics-based relationships between stratigraphic curvature and fracturing. The objective of this research is to investigate the potential of multicomponent surface sensor arrays, and passive seismic sources in the form of local earthquakes to identify and characterize potential fractured gas reservoirs located near seismically active regions. To assess the feasibility of passive seismic fracture detection and characterization, we have developed numerical codes for modeling elastic wave propagation in reservoir structures containing multiple, finite-length fractures. This article describes our efforts to determine the conditions for favorable excitation of fracture converted waves, and to develop an imaging method that can be used to locate and characterize fractures using multicomponent, passive seismic data recorded on a surface array.

  18. Hydrogen fracture toughness tester completion

    Energy Technology Data Exchange (ETDEWEB)

    Morgan, Michael J. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2015-09-30

    The Hydrogen Fracture Toughness Tester (HFTT) is a mechanical testing machine designed for conducting fracture mechanics tests on materials in high-pressure hydrogen gas. The tester is needed for evaluating the effects of hydrogen on the cracking properties of tritium reservoir materials. It consists of an Instron Model 8862 Electromechanical Test Frame; an Autoclave Engineering Pressure Vessel, an Electric Potential Drop Crack Length Measurement System, associated computer control and data acquisition systems, and a high-pressure hydrogen gas manifold and handling system.

  19. Fracture of nanoporous organosilicate thin films

    Science.gov (United States)

    Gage, David Maxwell

    density that results from higher network connectivity along with slight densification of the film. At the same time, the curing produced only a modest progressive increase in dielectric constant, indicating that ultra-violet and electron beam curing show great promise for the processing of low-k and ultra low-k organosilicate films. However, some general limitations of the curing processes were also discovered. In particular, the cohesive fracture energies of organosilicate films were found to be largely insensitive to curing. This was shown to be due to a crack meandering phenomenon in which the crack undergoes small-scale deflections toward local regions of free volume and reduced network bond density, thereby mitigating the effects of curing. Additionally, neither ultra-violet nor electron-beam curing were successful at improving adhesion at the lower film to barrier interface, suggesting little or no curing effects at the bottom portion of the dielectric layer. Sol-gel condensation of carbon-bridged organosilanes was used to prepare low-k films that feature hydrocarbon network bonds in lieu of terminal organic substituents. The hydrocarbon ligaments served to preserve connectivity and reinforce the glass network, resulting in remarkable improvements in elastic modulus and fracture resistance relative to competing carbon-doped oxides or SSQ derived materials of the same dielectric constant. The improvements in fracture resistance were rationalized in terms of a bridging contribution during stretching and rupture of the hydrocarbon chains that was found to scale with the length of the bridging hydrocarbon group. Additionally, the Si-C bonds in the bridged organosilicates made these films less prone to moisture assisted cracking than their silica-based and SSQ counterparts. The bridged organosilicate films demonstrated outstanding mechanical properties even at high porosity, making them excellent candidates for ultra low-k porous applications. The impact of pore

  20. Optimal scaling in ductile fracture

    Science.gov (United States)

    Fokoua Djodom, Landry

    This work is concerned with the derivation of optimal scaling laws, in the sense of matching lower and upper bounds on the energy, for a solid undergoing ductile fracture. The specific problem considered concerns a material sample in the form of an infinite slab of finite thickness subjected to prescribed opening displacements on its two surfaces. The solid is assumed to obey deformation-theory of plasticity and, in order to further simplify the analysis, we assume isotropic rigid-plastic deformations with zero plastic spin. When hardening exponents are given values consistent with observation, the energy is found to exhibit sublinear growth. We regularize the energy through the addition of nonlocal energy terms of the strain-gradient plasticity type. This nonlocal regularization has the effect of introducing an intrinsic length scale into the energy. We also put forth a physical argument that identifies the intrinsic length and suggests a linear growth of the nonlocal energy. Under these assumptions, ductile fracture emerges as the net result of two competing effects: whereas the sublinear growth of the local energy promotes localization of deformation to failure planes, the nonlocal regularization stabilizes this process, thus resulting in an orderly progression towards failure and a well-defined specific fracture energy. The optimal scaling laws derived here show that ductile fracture results from localization of deformations to void sheets, and that it requires a well-defined energy per unit fracture area. In particular, fractal modes of fracture are ruled out under the assumptions of the analysis. The optimal scaling laws additionally show that ductile fracture is cohesive in nature, i.e., it obeys a well-defined relation between tractions and opening displacements. Finally, the scaling laws supply a link between micromechanical properties and macroscopic fracture properties. In particular, they reveal the relative roles that surface energy and microplasticity

  1. EGS in sedimentary basins: sensitivity of early-flowback tracer signals to induced-fracture parameters

    Science.gov (United States)

    Karmakar, Shyamal; Ghergut, Julia; Sauter, Martin

    2015-04-01

    Artificial-fracture design, and fracture characterization during or following stimulation treatment is a central aspect of many EGS ('enhanced' or 'engineered' geothermal system) projects. During the creation or stimulation of an EGS, the injection of fluids, followed by flowback and production stages offers the opportunity for conducting various tracer tests in a single-well (SW) configuration, and given the typical operational and time limitations associated with such tests, along with the need to assess treatment success in real time, investigators mostly favour using short-time tracer-test data, rather than awaiting long-term 'tailings' of tracer signals. Late-time tracer signals from SW injection-flowback and production tests have mainly been used for the purpose of multiple-fracture inflow profiling in multi-layer reservoirs [1]. However, the potential of using SW short-term tracer signals for fracture characterization [2, 3] remained little explored as yet. Dealing with short-term flowback signals, we face a certain degree of parameter interplay, leading to ambiguity in fracture parameter inversion from the measured signal of a single tracer. This ambiguity can, to a certain extent, be overcome by - combining different sources of information (lithostratigraphy, and hydraulic monitoring) in order to constrain the variation range of hydrogeologic parameters (matrix and fracture permeability and porosity, fracture size), - using different types of tracers, such as conservative tracer pairs with contrasting diffusivity, or tracers pairs with contrasting sorptivity onto target surfaces. Fracture height is likely to be constrained by lithostratigraphy, while fracture length is supposed to be determinable from hydraulic monitoring (pressure recordings); the flowback rate can be assumed as a known (measurable) quantity during individual-fracture flowback. This leaves us with one or two unknown parameters to be determined from tracer signals: - the transport

  2. Meteorite Fractures and Scaling for Atmospheric Entry

    Science.gov (United States)

    Bryson, Kathryn L.; Ostrowski, Daniel R.

    2016-10-01

    We are attempting to understand the behavior of asteroids entering the atmosphere in order to help quantify the impact hazard. The strength of meteorites plays a critical role in determining the outcome of their impact events. Our objective is to scale fracture parameters in meteorites to their parent body.In this study over a thousand meteorite fragments in the Natural History Museums of Vienna and London (mostly hand-sized, some 40 or 50 cm across) were examined and fracture patterns in selected fragments were imaged. We identified six kinds of fracturing behavior. The density and length of the observed fractures were measured in hand specimens and thin sections. We assume that fracturing follows the Weibull distribution, where fractures are assumed to be randomly distributed through the target and the likelihood of encountering a fracture increases with distance. The images collected of the six fracture behaviors provide a two-dimensional view of the fractures. A relationship exists between the distributions of measured trace length and actual fracture size, where the slope of a log-log plot of trace length vs fracture density is proportional to α, the shape parameter. The value for α is unclear and a large range in α has been determined from light curve data. α can be used to scale strengths from the meteorite to the larger parent body.The majority of the meteorite fractures imaged displayed no particular sensitivity to meteorite texture. A value of α of 0.185 has been determined for a chondrite with a fracture pattern that shows no sensitivity to meteorite texture and has no point of origin. This study will continue to examine additional meteorites with similar fracture patterns along with the other 5 patterns to see if there is a correlation between fracture pattern and α. This may explain the variations in α determined from fireball data. Values of α will be used in models created by the Asteroid Threat Assessment Project to try to determine the

  3. 裂隙岩体三维渗透张量及表征单元体积的确定%ESTIMATION OF REPRESENTATIVE ELEMENTARY VOLUME AND THREE-DIMENSIONAL PERMEABILITY TENSOR FOR FRACTURED ROCK MASSES

    Institute of Scientific and Technical Information of China (English)

    吴锦亮; 何吉; 陈胜宏

    2014-01-01

    Both numerical methods and single-hole packer tests are used in study of the representative elementary volume(REV) and three-dimensional(3D) permeability tensor for fractured rock masses. Based on the probability distribution functions and corresponding statistical parameters investigated in field,3D stochastic discrete fracture networks are randomly generated using the Monte Carlo method. The composite element method(CEM) is used to obtain the permeability tensor and REV of rock masses,with a large quantity of calculations concerning different sample sizes in various directions. The permeability tensor is then modified and improved by using single-hole packer test results. Finally, the proposed method is used in determining the permeability properties of dam foundation of Xiaowan hydropower station. The results show that the proposed method is feasible and reliable.%将基于复合单元法的数值试验和现场单孔压水试验相结合,对裂隙岩体的三维渗透张量及表征单元体积(REV)进行研究。首先根据研究域岩体的裂隙统计参数及分布规律,运用蒙特卡罗方法在统计域内生成三维随机裂隙网络,然后利用复合单元法计算不同尺寸岩体试件在不同方向上的等效渗透系数,以此计算岩体的三维渗透张量及REV尺度,最后利用现场单孔压水试验结果来修正裂隙岩体的3个渗透主值。在小湾水电站工程中,运用该方法对坝区岩体的三维渗透特性进行分析,得到修正后的岩体三维渗透张量,分析结果表明,结合单孔压水试验和基于复合单元法的数值试验来确定裂隙岩体的三维渗透张量和REV是合理且有效的。

  4. The ideal dimensions of a Halbach cylinder of finite length

    CERN Document Server

    Bjørk, R

    2014-01-01

    In this paper the smallest or optimal dimensions of a Halbach cylinder of a finite length for a given sample volume and desired flux density are determined using numerical modeling and parameter variation. A sample volume that is centered in and shaped as the Halbach cylinder bore but with a possible shorter length is considered. The external radius and the length of the Halbach cylinder with the smallest possible dimensions are found as a function of a desired internal radius, length of the sample volume and mean flux density. It is shown that the optimal ratio between the outer and inner radius of the Halbach cylinder does not depend on the length of the sample volume. Finally, the efficiency of a finite length Halbach cylinder is considered and compared with the case of a cylinder of infinite length. The most efficient dimensions for a Halbach cylinder are found and it is shown that the efficiency increases slowly with the length of the cylinder.

  5. Fracture Behavior of Dielectric Elastomer under Pure Shear Loading

    Science.gov (United States)

    Ahmad, D.; Patra, K.

    2017-09-01

    Dielectric elastomer has become a very important material for many emerging applications areas like optics, micro fluidics, sensors, actuators and energy harvesting. However, these elastomer components are prone to fracture or catastrophic failure because of defects likes notches, flaws, and fatigue crack, impurities which occur during production or during service. To make better use of this material, it is important to investigate fracture characteristics under different operating conditions. This study experimentally investigated the effects of notch length and strain rate on the fracture toughness, failure stretch and failure stress of acrylic elastomer under pure shear deformation mode. It is observed that failure stretch depends on notch length and independent of strain rate, but failure stress decreases with increasing notch length and increases with increasing strain rate. It is also found that fracture toughness is independent of notch lengths. However, fracture toughness is found to increase with strain rate.

  6. Electronics Reliability Fracture Mechanics, Volume 2. Fracture Mechanics

    Science.gov (United States)

    1992-05-01

    180 * Ackerman Water 5 1 30.50 34-92 2.0 - Koch Air 1.4-10 1 20 30.190 - -- * Wamsler Air 2.05-8.9 1 15-30 55-240 0I 1* Saunders Nitrogen 0.11 250...obtained from geometry A 1 sin2, +tan2 *(2 * - - sin2W (4a) R •2 2 2 a -1 -cos, + tanq , (1 -sin,) (4b) T P - -- -K [- -cos* +tani(i -sin*)] (4c) r aa(D

  7. Multi-scale approach to invasion percolation of rock fracture networks

    CERN Document Server

    Ebrahimi, Ali N; Araújo, Nuno A M; Herrmann, Hans J

    2014-01-01

    A multi-scale scheme for the invasion percolation of rock fracture networks with heterogeneous fracture aperture fields is proposed. Inside fractures, fluid transport is calculated on the finest scale and found to be localized in channels as a consequence of the aperture field. The channel network is characterized and reduced to a vectorized artificial channel network (ACN). Different realizations of ACNs are used to systematically calculate efficient apertures for fluid transport inside differently sized fractures as well as fracture intersection and entry properties. Typical situations in fracture networks are parameterized by fracture inclination, flow path length along the fracture and intersection lengths in the entrance and outlet zones of fractures. Using these scaling relations obtained from the finer scales, we simulate the invasion process of immiscible fluids into saturated discrete fracture networks, which were studied in previous works.

  8. Subcritical growth of natural hydraulic fractures

    Science.gov (United States)

    Garagash, D.

    2014-12-01

    Joints are the most common example of brittle tensile failure in the crust. Their genesis at depth is linked to the natural hydraulic fracturing, which requires pore fluid pressure in excess of the minimum in situ stress [Pollard and Aidyn, JSG1988]. Depending on the geological setting, high pore pressure can result form burial compaction of interbedded strata, diagenesis, or tectonics. Common to these loading scenarios is slow build-up of pore pressure over a geological timescale, until conditions for initiation of crack growth are met on favorably oriented/sized flaws. The flaws can vary in size from grain-size cracks in igneous rocks to a fossil-size flaws in clastic rock, and once activated, are inferred to propagate mostly subcritically [Segall JGR 1984; Olson JGR 1993]. Despite many observational studies of natural hydraulic fractures, the modeling attempts appear to be few [Renshaw and Harvey JGR 1994]. Here, we use boundary integral formulation for the pore fluid inflow from the permeable rock into a propagating joint [Berchenko et al. IJRMMS 1997] coupled with the criteria for subcritical propagation assisted by the environmental effects of pore fluid at the crack tip to solve for the evolution of a penny-shape joint, which, in interbedded rock, may eventually evolve to short-blade geometry (propagation confined to a bed). Initial growth is exceedingly slow, paced by the stress corrosion reaction kinetics at the crack tip. During this stage the crack is fully-drained (i.e. the fluid pressure in the crack is equilibrated with the ambient pore pressure). This "slow" stage is followed by a rapid acceleration, driven by the increase of the mechanical stress intensity factor with the crack length, towards the terminal joint velocity. We provide an analytical expression for the latter as a function of the rock diffusivity, net pressure loading at the initiation (or flaw lengthscale), and parameters describing resistance to fracture growth. Due to a much slower

  9. Characterization and interpretation of a fractured rocky massif from borehole data. Boreholes of geothermal project at Soultz-sous-Forets and other examples of unidirectional sampling; Caracterisation et interpretation d`un volume rocheux fracture a partir de donnees de forages. Les forages geothermiques de Soultz-sous-Forets et autres exemples d`echantillonnages unidirectionnels

    Energy Technology Data Exchange (ETDEWEB)

    Dezayes, CH.

    1995-12-18

    In this thesis, we study fractures from borehole data on two sites: in one, located at Soultz-sous-Forets (Alsace) in the Rhine graben, boreholes reach a delta Jurassic series forming a petroleum reservoir. At Soultz, fractures have been studied on cores and borehole images. Striated faults present on cores permit to determine the tectonic history of the granite, completed by field study in Vosges Massif. This history corresponds to the Rhine graben history knowing by different authors. The analysis of vertical induced fractures observed on borehole images indicates a present-day NW-SE to NNW-SSE compression. These variations of stress direction are confirmed by others in situ measurements, as hydraulic injection, micro-seismicity, etc... On cores and borehole images, numerous fractures have been observed. Most of them are linked to the E-W distension, which permits the Rhine graben opening at Oligocene. At greatest scale, in quartz minerals, the micro-fractures are constitute by fluid inclusion trails. Several sets are related to the E-W distension, but others sets are linked to compressive stages. These sets are not observed on cores. This is a under-sampling of some fractures by the boreholes, but theses fractures exit into to rock massif. On borehole images, fracture density is weakest than the cores, however the set organisation is the same. At Ravenscar, the distribution of fracture spacing along different unidirectional sampling shows a exponential negative law. However, the fracture density varies with sampling. (author) 199 refs.

  10. Fracture mechanics solution of confined water progressive intrusion height of mining fracture floor

    Institute of Scientific and Technical Information of China (English)

    Lu Haifeng; Yao Duoxi; Shen Dan; Cao Jiyang

    2015-01-01

    In order to obtain the value of confined water progressive intrusion height of mining fracture floor, the analysis equation was deduced based on the fracture extension theory of the fracture mechanics. Further-more, the influence of some parameters (e.g., advancing distance of working face, water pressure, initial fracture length and its angle) on confined water progressive intrusion height were analyzed. The results indicate that tension-shearing fracture of floor is extended more easily than compression-shearing frac-ture under the same conditions. When floor fracture dip angle is less than 90?, tension-shearing extension occurs more easily on the left edge of the goaf. If fracture dip angle is larger than 90?, it occurs more easily on the right edge of the goaf. The longer the advancing distance of working face is, the greater initial frac-ture length goes; or the larger water pressure is, the greater possibility of tension-shearing extension occurs. The confined water progressive intrusion height reaches the maximum on the edge of the goaf. Field in situ test is consistent with the theoretical analysis result.

  11. Correlation analysis of postoperative blood volume changes and delirium in elderly patients undergoing surgery for hip fracture%老年髋部骨折术后血容量改变与谵妄的相关分析

    Institute of Scientific and Technical Information of China (English)

    王雪飞; 韩莹; 杨莉; 郑莹; 任文秀; 于振山

    2012-01-01

    目的 探讨谵妄与老年髋部骨折患者术后血容量改变的相关性,为治疗和预防提供参考.方法 连续性观察150例接受手术治疗的老年髋部骨折患者.谵妄的评估采用CAM(confusion assessment method)量表.收集其术前、术中及术后的数据,用Logistic回归分析血容量改变与谵妄的相关性.结果 59例患者(男28例,女31例)术后出现了谵妄,发生率为39.3%(59/150).谵妄组平均年龄(77.71 ±6.63)岁,高于无谵妄组患者(73.79±5.42)岁,两组比较差异有统计学意义(t=-3.958,P<0.001).谵妄组患者术前及术后第7天平均血红蛋白浓度、红细胞比容均低于未出现谵妄组[术前分别为(117.80±16.59)、(123.92±14.61)g/L,t =2.378,P=0.019;0.355±0.154、0.372±0.210,t =2.291,P=0.023;术后第7天(98.15±11.51)、(102.33±9.88) g/L,t=2.369,P=0.019;0.296±0.040、0.306±0.030,t=-3.958,P<0.001].两组间在性别、骨折类型、手术方式、手术时间、失血量及术后1、3d血红蛋白浓度间差异无统计学意义(P均>0.05).经Logistic回归分析,患者的年龄、教育程度及术后第7天血红蛋白含量在是否出现谵妄两组间差异有统计学意义(OR分别为3.28、1.097、0.389,P均<0.05).结论 高龄髋部骨折患者发生谵妄是一个多因素结果,高龄、术后持续低血红蛋白浓度、受教育程度低患者的谵妄发生概率高.%Objective To explore the relationship of blood volume changes and postoperative delirium in elderly patients undergoing surgery for hip fracture.Methods One hundred and fifty elderly patients who underwent surgery for hip fracture were enrolled in the study.Delirium was diagnosed by Confusion Assessment Method(CAM).Preoperative,intraoperative and postoperative data were collected,and the correlation of postoperative delirium and blood volume changes were analyzed by logistic regression analysis.Results A total of 59 patients(28 males and 31 females)had delirium after surgery and the

  12. Biological Plating in Comminuted Subtrochanteric Fractures

    Directory of Open Access Journals (Sweden)

    MR Aghamirsalim

    2012-05-01

    Full Text Available Background: Comminuted subtrochanteric fractures have been a challenge for orthopedic surgeons in terms of appropriate reduction and stable fixation. Numerous methods have been used for the fixation of comminuted subtrochanteric fractures among which some are accompanied with technical difficulties and complications of their own. Regarding the results of previous studies, we decided to evaluate the biological fixation method in comminuted subtrochanteric fractures. Methods: In this prospective study, we evaluated 20 men with comminuted subtrochanteric femoral fractures. The patients underwent indirect reduction with dynamic hip screw (DHS or dynamic condylar screw (DCS fixation within one week of injury. The patients were evaluated clinically for pain, hip and knee range of motion, leg-length discrepancy and angular and rotational deformities, in addition the radiographic assessment of the union. Results: According to Seinsheimer's classification of subtrochanteric fractures, four patients had type III, nine had type IV and seven had type V fractures. Fracture fixation was performed by DCS in eight and by DHS in 12 cases. The average time of the operations was 79.4 (ranging from 60-125 minutes. Mean blood loss was 634 (ranging from 340-1160 milliliters. Uneventfully, union occurred in all patients with no clinical pain or dysfunction. Conclusion: Submuscular plating with either DCS or DHS is a viable option to treat comminuted subtrochanteric fractures. The results of this study highly suggest use of submuscular plating in the treatment of comminuted subtrochanteric fractures, especially in the third world countries.

  13. Application of Stochastic Fracture Network with Numerical Fluid Flow Simulations to Groundwater Flow Modeling in Fractured Rocks

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The continuum approach in fluid flow modeling is generally applied to porous geological media,but has limitel applicability to fractured rocks. With the presence of a discrete fracture network relatively sparsely distributed in the matrix, it may be difficult or erroneous to use a porous medium fluid flow model with continuum assumptions to describe the fluid flow in fractured rocks at small or even large field scales. A discrete fracture fluid flow approach incorporating a stochastic fracture network with numerical fluid flow simulations could have the capability of capturing fluid flow behaviors such as inhomogeneity and anisotropy while reflecting the changes of hydraulic features at different scales.Moreover, this approach can be implemented to estimate the size of the representative elementary volume (REV) in order to find out the scales at which a porous medium flow model could be applied, and then to determine the hydraulic conductivity tensor for fractured rocks. The following topics are focused on in this study: (a) conceptual discrete fracture fluid flow modeling incorporating a stochastic fracture network with numerical flow simulations; (b) estimation of REVand hydraulic conductivity tensor for fractured rocks utilizing a stochastic fracture network with numerical fluid flow simulations; (c) investigation of the effect of fracture orientation and density on the hydraulic conductivity and REV by implementing a stochastic fracture network with numerical fluid flow simulations, and (d) fluid flow conceptual models accounting for major and minor fractures in the 2-D or 3-D flow fields incorporating a stochastic fracture network with numerical fluid flow simulations.``

  14. Hydraulic Properties of Fractured Rock Samples at In-Situ Conditions - Insights from Lab Experiments Using X-Ray Tomography

    Science.gov (United States)

    Nehler, Mathias; Stöckhert, Ferdinand; Duda, Mandy; Renner, Jörg; Bracke, Rolf

    2017-04-01

    The hydraulic properties of low-porosity rock formations are controlled by the geometry of open fractures, joints and faults. Aperture, surface roughness, accessible length, and thus, the volume available for fluids associated of such interfaces are strongly affected by their state of stress. Moreover, these properties may evolve with time in particular due to processes involving chemically active fluids. Understanding the physico-chemical interactions of rocks with fluids at reservoir conditions will help to predict the long-term reservoir development and to increase the efficiency of geothermal power plants. We designed an x-ray transparent flow-through cell. Confining pressure can be up to 50 MPa and pore fluid can currently be circulated through the sample with pressures of up to 25 MPa. All wetted parts are made of PEEK to avoid corrosion when using highly saline fluids. Laboratory experiments were performed to investigate hydraulic properties of fractured low-porosity samples under reservoir conditions while x-rays transmit the sample. The cell is placed inside a µCT scanner with a 225 kV multifocal x-ray tube for high resolution x-ray tomography. Samples measure 10 mm in diameter and 25 mm in length resulting in a voxel resolution of approximately 10 µm. Samples with single natural as well as artificial fractures were subjected to various confining pressures ranging from 2.5 MPa to 25 MPa. At each pressure level, effective permeability was determined from steady-state flow relying on Darcy's law. In addition, a full 3D image was recorded by the µCT scanner to gain information on the fracture aperture and geometry. Subvolumes (400x400x400 voxels) of the images were analyzed to reduce computational cost. The subvolumes were filtered in 3D with an edge preserving non-local means filter. Further quantification algorithms were implemented in Matlab. Segmentation into pore space and minerals was done automatically for all datasets by a peak finder algorithm

  15. Correlation of transmissive fractures in pilot holes ONK-PH8 - PH12 and fracture traces mapped in ONKALO

    Energy Technology Data Exchange (ETDEWEB)

    Palmen, J.; Nummela, J.; Ahokas, H. [Poeyry Finland Oy, Vantaa (Finland)

    2014-05-15

    fractures from the pilot holes ONK-PH8 - ONK-PH12 were imported as circle polygon objects to a 3D AutoCAD model. The mapped and verified 13 247 ONKALO fracture traces were divided to 3 subsets according to their length: (6 fracture traces in FDB (Fracture Database) were lacking the length attribute) 433 long fractures (length equal or greater than 10 m), 1 288 medium length fractures (length less than 10 m but equal or greater than 3.5 m) and 11 520 short fracture traces (length less than 3.5 m) and then imported to 3D model to be linked to hydraulically conductive fractures of pilot holes. The combining was carried out by investigating the location and orientation of each suspected pair of a polygon (PFL fracture) and a polyline in the 3D AutoCAD model. Additionally leakage attribute of each ONKALO fracture trace was considered as an conductivity indicator and the fracture traces bearing leakage classification were combined with the PFL fractures. (orig.)

  16. Compaction of aggregated ceramic powders: From contact laws to fracture and yield surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Pizette, P.; Martin, C. L. [UJF, CNRS, Lab SIMAP, INP, Grenoble GPM2, F-38402 St Martin Dheres (France); Pizette, P.; Delette, G. [CEA Grenoble, DRT LITEN DTH LEV, F-38054 Grenoble 9 (France); Sornay, P. [CEA Cadarache, DEN DEC SPUA LCU, F-13108 St Paul Les Durance (France); Sans, F. [AREVA MELOX DT DIP, F-30203 Bagnols Sur Ceze (France)

    2010-07-01

    This work describes a methodology based on Discrete Element Method (DEM) simulations to generate yield and fracture surfaces for aggregated ceramic powders. The DEM simulations, which consider the length scale of porous aggregates are used as numerical triaxial experiments to obtain the behavior of a small volume element of powder under a given load. The experimental identification procedure, which relies on the design of experiment method, is designed to limit the number of experiments and simulations needed to obtain the model material parameters. These material parameters, which model the interactions between aggregates in the DEM simulations are identified using two simple experiments on a uranium dioxide powder: closed-die compaction and diametrical compression test. The yield and fracture surfaces obtained from the DEM simulations provide valuable information on the behavior of the powder for stress states that are difficult or impossible to attain in complex triaxial tests. (authors)

  17. New length operator for loop quantum gravity

    CERN Document Server

    Ma, Yongge; Yang, Jinsong

    2010-01-01

    An alternative expression for the length operator in loop quantum gravity is presented. The operator is background-independent, symmetric, positive semi-definite, and well-defined on the kinematical Hilbert space. The expression for the regularized length operator can moreover be understood both from a simple geometrical perspective as the average of a formula relating the length to area, volume and flux operators, and also consistently as the result of direct substitution of the densitized triad operator with the functional derivative operator into the regularized expression of the length. Both these derivations are discussed, and the origin of an undetermined overall factor in each case is also elucidated.

  18. Growth Plate Fractures

    Science.gov (United States)

    ... the most widely used by doctors is the Salter-Harris system, described below. Type I Fractures These ... incidence of growth plate fractures peaks in adolescence. Salter-Harris classification of growth plate fractures. AAOS does ...

  19. Bias in the Weibull Strength Estimation of a SiC Fiber for the Small Gauge Length Case

    Science.gov (United States)

    Morimoto, Tetsuya; Nakagawa, Satoshi; Ogihara, Shinji

    It is known that the single-modal Weibull model describes well the size effect of brittle fiber tensile strength. However, some ceramic fibers have been reported that single-modal Weibull model provided biased estimation on the gauge length dependence. A hypothesis on the bias is that the density of critical defects is very small, thus, fracture probability of small gauge length samples distributes in discrete manner, which makes the Weibull parameters dependent on the gauge length. Tyranno ZMI Si-Zr-C-O fiber has been selected as an example fiber. The tensile tests have been done on several gauge lengths. The derived Weibull parameters have shown a dependence on the gauge length. Fracture surfaces were observed with SEM. Then we classified the fracture surfaces into the characteristic fracture patterns. Percentage of each fracture pattern was found dependent on the gauge length, too. This may be an important factor of the Weibull parameter dependence on the gauge length.

  20. The ideal dimensions of a Halbach cylinder of finite length

    DEFF Research Database (Denmark)

    Bjørk, Rasmus

    2011-01-01

    but with a possible shorter length is considered. The external radius and the length of the Halbach cylinder with the smallest possible dimensions are found as a function of a desired internal radius, length of the sample volume and mean flux density. It is shown that the optimal ratio between the outer and inner...... radius of the Halbach cylinder does not depend on the length of the sample volume. Finally, the efficiency of a finite length Halbach cylinder is considered and compared with the case of a cylinder of infinite length. The most efficient dimensions for a Halbach cylinder are found and it is shown...

  1. Acidization of shales with calcite cemented fractures

    Science.gov (United States)

    Kwiatkowski, Kamil; Szymczak, Piotr; Jarosiński, Marek

    2017-04-01

    Investigation of cores drilled from shale formations reveals a relatively large number of calcite-cemented fractures. Usually such fractures are reactivated during fracking and can contribute considerably to the permeability of the resulting fracture network. However, calcite coating on their surfaces effectively excludes them from production. Dissolution of the calcite cement by acidic fluids is investigated numerically with focus on the evolution of fracture morphology. Available surface area, breakthrough time, and reactant penetration length are calculated. Natural fractures in cores from Pomeranian shale formation (northern Poland) were analyzed and classified. Representative fractures are relatively thin (0.1 mm), flat and completely sealed with calcite. Next, the morphology evolution of reactivated natural fractures treated with low-pH fluids has been simulated numerically under various operating conditions. Depth-averaged equations for fracture flow and reactant transport has been solved by finite-difference method coupled with sparse-matrix solver. Transport-limited dissolution has been considered, which corresponds to the treatment with strong acids, such as HCl. Calcite coating in reactivated natural fractures dissolves in a highly non-homogeneous manner - a positive feedback between fluid transport and calcite dissolution leads to the spontaneous formation of wormhole-like patterns, in which most of the flow is focused. The wormholes carry reactive fluids deeper inside the system, which dramatically increases the range of the treatment. Non-uniformity of the dissolution patterns provides a way of retaining the fracture permeability even in the absence of the proppant, since the less dissolved regions will act as supports to keep more dissolved regions open. Evolution of fracture morphology is shown to depend strongly on the thickness of calcite layer - the thicker the coating the more pronounced wormholes are observed. However the interaction between

  2. Fracture propagation in sandstone and slate e Laboratory experiments, acoustic emissions and fracture mechanics

    Institute of Scientific and Technical Information of China (English)

    Ferdinand Stoeckhert; Michael Molenda; Sebastian Brenne; Michael Alber

    2015-01-01

    abstract Fracturing of highly anisotropic rocks is a problem often encountered in the stimulation of unconven-tional hydrocarbon or geothermal reservoirs by hydraulic fracturing. Fracture propagation in isotropic material is well understood but strictly isotropic rocks are rarely found in nature. This study aims at the examination of fracture initiation and propagation processes in a highly anisotropic rock, specifically slate. We performed a series of tensile fracturing laboratory experiments under uniaxial as well as triaxial loading. Cubic specimens with edge lengths of 150 mm and a central borehole with a diameter of 13 mm were prepared from Fredeburg slate. An experiment using the rather isotropic Bebertal sandstone as a rather isotropic rock was also performed for comparison. Tensile fractures were generated using the sleeve fracturing technique, in which a polymer tube placed inside the borehole is pressurized to generate tensile fractures emanating from the borehole. In the uniaxial test series, the loading was varied in order to observe the transition from strength-dominated fracture propagation at low loading mag-nitudes to stress-dominated fracture propagation at high loading magnitudes.

  3. Fibula fracture stabilization with a guide wire as supplementary fixation in tibia fractures.

    Science.gov (United States)

    Dombroski, Derek; Scolaro, John A; Pulos, Nicholas; Beingessner, Daphne M; Dunbar, Robert; Mehta, Samir

    2012-05-01

    The tibia is the most commonly fractured long bone. Although the goals of fracture management are straightforward, methods for achieving anatomical alignment and stable fixation are limited. Type of management depends on fracture pattern, local soft-tissue involvement, and systemic patient factors. Tibial shaft fractures with concomitant fibula fractures, particularly those at the same level, may be difficult to manage because of their inherent instability. Typically, management of lower extremity fractures is focused on the tibia fixation, and the associated fibula fracture is managed without fixation. In this article, we describe a novel technique for intramedullary fixation of the fibula, using a humeral guide wire as an adjunct to tibia fixation in the setting of tibial shaft fracture. This technique aids in determining length, alignment, and rotation of the tibia fracture and may help support the lower extremity as whole by stabilizing the lateral column. In addition, this technique can be used to help maintain reduction of the fibula when there is concern about the soft tissues of the lower extremity secondary to swelling or injury. Our clinical case series demonstrates the safety, effectiveness, and cost-sensitivity of this technique in managing select concurrent fractures of the tibia and fibula.

  4. Hydraulic fracture model comparison study: Complete results

    Energy Technology Data Exchange (ETDEWEB)

    Warpinski, N.R. [Sandia National Labs., Albuquerque, NM (United States); Abou-Sayed, I.S. [Mobil Exploration and Production Services (United States); Moschovidis, Z. [Amoco Production Co. (US); Parker, C. [CONOCO (US)

    1993-02-01

    Large quantities of natural gas exist in low permeability reservoirs throughout the US. Characteristics of these reservoirs, however, make production difficult and often economic and stimulation is required. Because of the diversity of application, hydraulic fracture design models must be able to account for widely varying rock properties, reservoir properties, in situ stresses, fracturing fluids, and proppant loads. As a result, fracture simulation has emerged as a highly complex endeavor that must be able to describe many different physical processes. The objective of this study was to develop a comparative study of hydraulic-fracture simulators in order to provide stimulation engineers with the necessary information to make rational decisions on the type of models most suited for their needs. This report compares the fracture modeling results of twelve different simulators, some of them run in different modes for eight separate design cases. Comparisons of length, width, height, net pressure, maximum width at the wellbore, average width at the wellbore, and average width in the fracture have been made, both for the final geometry and as a function of time. For the models in this study, differences in fracture length, height and width are often greater than a factor of two. In addition, several comparisons of the same model with different options show a large variability in model output depending upon the options chosen. Two comparisons were made of the same model run by different companies; in both cases the agreement was good. 41 refs., 54 figs., 83 tabs.

  5. Pediatric Hip Fractures in California: Results from a Community-Based Hip Fracture Registry.

    Science.gov (United States)

    Prentice, Heather A; Paxton, Elizabeth W; Hunt, Jessica J; Grimsrud, Christopher D; Weiss, Jennifer M

    2017-01-01

    Hip fracture registries offer an opportunity to identify and to monitor patients with rare conditions and outcomes, including hip fractures in pediatric patients. To report patient demographics and surgical outcomes of pediatric patients treated surgically for hip fractures in a large integrated health care system. Pediatric patients (fracture) with hip fractures were identified between 2009 and 2012 using our health care system's hip fracture registry. Patient characteristics, type of fracture, surgical treatment, and short-term complications. Among 39 patients identified, 31 (79.5%) were male, and the median age was 15 years old (interquartile range: 11-17 years). Most patients were Hispanic (n = 17, 43.6%) or white (n = 14, 35.9%). There were 8 patients (20.5%) with 15 comorbidities. Delbet Type IV (intertrochanteric) fractures were the most common fracture type (n = 22, 56.4%), and fixation method was equally distributed between intramedullary, screw and sideplate, and screws (n = 12, 30.8% for each). Most surgeries were performed by medium-volume surgeons (n = 22, 56.4%) at medium- and high-volume hospitals (n = 37, 94.9%). Three 90-day readmissions (7.7%), 1 infection (2.6%), 1 malunion (2.6%), and 1 revision (2.6%) were observed in this cohort during the study period. In our series using registry data, hip fractures younger than age 21 years were more common in boys and Hispanic patients. Intertrochanteric fractures (Delbet Type IV) were the most frequently observed type in our community-based hip fracture registry. Short-term complications were infrequent.

  6. Fractures of the distal radius (Colles' fracture)

    National Research Council Canada - National Science Library

    João Carlos Belloti; João Baptista Gomes dos Santos; Álvaro Nagib Atallah; Walter Manna Albertoni; Flavio Faloppa

    2007-01-01

    CONTEXT AND OBJECTIVE: Although Colles' fracture is a common clinical situation for the orthopedist, we did not find any information in the literature that would allow safe decision-making on the best treatment for each fracture type...

  7. Posterior paramedian subrhomboidal analgesia versus thoracic epidural analgesia for pain control in patients with multiple rib fractures.

    Science.gov (United States)

    Shelley, Casey L; Berry, Stepheny; Howard, James; De Ruyter, Martin; Thepthepha, Melissa; Nazir, Niaman; McDonald, Tracy; Dalton, Annemarie; Moncure, Michael

    2016-09-01

    Rib fractures are common in trauma admissions and are associated with an increased risk of pulmonary complications, intensive care unit admissions, and mortality. Providing adequate pain control in patients with multiple rib fractures decreases the risk of adverse events. Thoracic epidural analgesia is currently the preferred method for pain control. This study compared outcomes in patients with multiple acute rib fractures treated with posterior paramedian subrhomboidal (PoPS) analgesia versus thoracic epidural analgesia (TEA). This prospective study included 30 patients with three or more acute rib fractures admitted to a Level I trauma center. Thoracic epidural analgesia or PoPS catheters were placed, and local anesthesia was infused. Data were collected including patients' pain level, adjunct morphine equivalent use, adverse events, length of stay, lung volumes, and discharge disposition. Nonparametric tests were used and two-sided p Pain rating was lower in the PoPS group (2.5 vs. 5; p = 0.03) after initial placement. Overall, there was no other statistically significant difference in pain control or use of oral morphine adjuncts between the groups. Hypotension occurred in eight patients, 75% with TEA and only 25% with PoPS. No difference was found in adverse events, length of stay, lung volumes, or discharge disposition. In patients with rib fractures, PoPS analgesia may provide pain control equivalent to TEA while being less invasive and more readily placed by a variety of hospital staff. This pilot study is limited by its small sample size, and therefore additional studies are needed to prove equivalence of PoPS compared to TEA. Therapeutic study, level IV.

  8. Fracture Propagation Driven by Fluid Outflow from a Low-permeability Reservoir

    CERN Document Server

    Gor, Gennady Yu

    2012-01-01

    Fracturing of the caprock during CO2 storage in deep saline aquifers can lead to leakage. Estimation of the rate of fracture propagation allows one to assess the leakage risk. Here we propose an analytical model for calculating the length of the fracture, which propagates due to the fluid outflow from a low-permeability aquifer. We present a self-similar solution of the pressure diffusion equation in the system of reservoir and fracture, allowing us to get the analytical expression for the fracture length as a function of time. We calculate the evolution of the fracture length for a characteristic aquifer. We show that the analytical solution provides an estimate from below for the fracture length, since the driving force for propagation grows with elevation.

  9. Mechanical Properties Comparing Composite Fiber Length to Amalgam

    Directory of Open Access Journals (Sweden)

    Richard C. Petersen

    2016-01-01

    Full Text Available Photocure fiber-reinforced composites (FRCs with varying chopped quartz-fiber lengths were incorporated into a dental photocure zirconia-silicate particulate-filled composite (PFC for mechanical test comparisons with a popular commercial spherical-particle amalgam. FRC lengths included 0.5-mm, 1.0 mm, 2.0 mm, and 3.0 mm all at a constant 28.2 volume percent. Four-point fully articulated fixtures were used according to American Standards Test Methods with sample dimensions of 2×2×50 mm3 across a 40 mm span to provide sufficient Euler flexural bending and prevent top-load compressive shear error. Mechanical properties for flexural strength, modulus, yield strength, resilience, work of fracture, critical strain energy release, critical stress intensity factor, and strain were obtained for comparison. Fiber length subsequently correlated with increasing all mechanical properties, p<1.1×10-5. Although the modulus was significantly statistically higher for amalgam than all composites, all FRCs and even the PFC had higher values than amalgam for all other mechanical properties. Because amalgams provide increased longevity during clinical use compared to the standard PFCs, modulus would appear to be a mechanical property that might sufficiently reduce margin interlaminar shear stress and strain-related microcracking that could reduce failure rates. Also, since FRCs were tested with all mechanical properties that statistically significantly increased over the PFC, new avenues for future development could be provided toward surpassing amalgam in clinical longevity.

  10. Measuring Thermodynamic Length

    Energy Technology Data Exchange (ETDEWEB)

    Crooks, Gavin E

    2007-09-07

    Thermodynamic length is a metric distance between equilibrium thermodynamic states. Among other interesting properties, this metric asymptotically bounds the dissipation induced by a finite time transformation of a thermodynamic system. It is also connected to the Jensen-Shannon divergence, Fisher information, and Rao's entropy differential metric. Therefore, thermodynamic length is of central interestin understanding matter out of equilibrium. In this Letter, we will consider how to denethermodynamic length for a small system described by equilibrium statistical mechanics and how to measure thermodynamic length within a computer simulation. Surprisingly, Bennett's classic acceptance ratio method for measuring free energy differences also measures thermodynamic length.

  11. Electrophilic acid gas-reactive fluid, proppant, and process for enhanced fracturing and recovery of energy producing materials

    Science.gov (United States)

    Fernandez, Carlos A.; Heldebrant, David J.; Bonneville, Alain H. R.; Jung, Hun Bok; Carroll, Kenneth

    2016-09-20

    An electrophilic acid gas-reactive fracturing and recovery fluid, proppant, and process are detailed. The fluid expands in volume to provide rapid and controlled increases in pressure that enhances fracturing in subterranean bedrock for recovery of energy-producing materials. Proppants stabilize openings in fractures and fissures following fracturing.

  12. An XFEM Model for Hydraulic Fracturing in Partially Saturated Rocks

    Directory of Open Access Journals (Sweden)

    Salimzadeh Saeed

    2016-01-01

    Full Text Available Hydraulic fracturing is a complex multi-physics phenomenon. Numerous analytical and numerical models of hydraulic fracturing processes have been proposed. Analytical solutions commonly are able to model the growth of a single hydraulic fracture into an initially intact, homogeneous rock mass. Numerical models are able to analyse complex problems such as multiple hydraulic fractures and fracturing in heterogeneous media. However, majority of available models are restricted to single-phase flow through fracture and permeable porous rock. This is not compatible with actual field conditions where the injected fluid does not have similar properties as the host fluid. In this study we present a fully coupled hydro-poroelastic model which incorporates two fluids i.e. fracturing fluid and host fluid. Flow through fracture is defined based on lubrication assumption, while flow through matrix is defined as Darcy flow. The fracture discontinuity in the mechanical model is captured using eXtended Finite Element Method (XFEM while the fracture propagation criterion is defined through cohesive fracture model. The discontinuous matrix fluid velocity across fracture is modelled using leak-off loading which couples fracture flow and matrix flow. The proposed model has been discretised using standard Galerkin method, implemented in Matlab and verified against several published solutions. Multiple hydraulic fracturing simulations are performed to show the model robustness and to illustrate how problem parameters such as injection rate and rock permeability affect the hydraulic fracturing variables i.e. injection pressure, fracture aperture and fracture length. The results show the impact of partial saturation on leak-off and the fact that single-phase models may underestimate the leak-off.

  13. Zolpidem Use and Risk of Fracture in Elderly Insomnia Patients

    OpenAIRE

    Kang, Dong-Yoon; Park, Soyoung; Rhee, Chul-Woo; Kim, Ye-Jee; Choi, Nam-Kyong; Lee, Joongyub; Park, Byung-Joo

    2012-01-01

    Objectives To evaluate the risk of fractures related with zolpidem in elderly insomnia patients. Methods Health claims data on the entire South Korean elderly population from January 2005 to June 2006 were extracted from the Health Insurance Review and Assessment Service database. We applied a case-crossover design. Cases were defined as insomnia patients who had a fracture diagnosis. We set the hazard period of 1 day length prior to the fracture date and four control periods of the same leng...

  14. Dual-source CT with multiplanar reconstruction and volume rendering three-dimensional reconstruction in the evaluation of rib fractures%双源CT结合多平面重建与容积再现三维重建技术评价肋骨骨折

    Institute of Scientific and Technical Information of China (English)

    钱斌; 邹新农; 姚选军; 陶广宇; 王凯; 陈宏伟

    2011-01-01

    背景:依靠胸部摄片诊断肋骨骨折常导致误诊和漏诊.目的:分析双源CT 结合三维重建技术在肋骨骨折中的应用价值.方法:使用双源CT 对65 例肋骨骨折患者进行薄层扫描,将数据发送至工作站行多平面重建、容积再现技术,得到肋骨骨折高清晰度的三维图像后,从不同角度观察骨折线走行、骨折移位及成角情况.结果与结论:双源CT 结合三维重建图像清晰显示65 例患者286 根骨折,其中52 例保守治疗,其余13 例行切开复位、内固定治疗.制定手术方案时均参考了三维重建图像,所显示的骨折部位、移位、成角等情况与术中所见一致.提示双源CT 能明确诊断肋骨骨折,多平面重建和容积再现技术互相补充对诊断肋骨骨折及指导治疗方案有明显的优势.%BACKGROUND: Diagnosis of rib fractures relying on the chest radiograph diagnosis often leads to misdiagnos is. OBJECTIVE: To investigate the application of dual-source CT with three-dimensional reconstruction in rib fractures. METHODS: Sixty-five patients with rib fractures were scanned with dual-source CT. The data were sent to the workstation line of multi-planar reconstruction using volume rendering technique, to obtain high-resolution three-dimersion al images of rib fractures, and to observe the fracture line courses, fracture displacement and angulation of the situation from different angles. RESULTS AND CONCLUSION: The combination of dual-source CT and three-dimensional reconstruction images clearly showed 286 fractures in 65 patients, including 52 cases of consenrvative treatment, and the remaining 13 cases of surgery. The surgery programs in all patients were developed with reference to three- dimensional reoonstruction images showing the fracture position, displacement, angulation. Etc., consistent with the intraoperative findings. Dual-source CT can confirm the diagnose of rib fractures, and multi-planar reconstruction and volume

  15. Compartmentalization analysis using discrete fracture network models

    Energy Technology Data Exchange (ETDEWEB)

    La Pointe, P.R.; Eiben, T.; Dershowitz, W. [Golder Associates, Redmond, VA (United States); Wadleigh, E. [Marathon Oil Co., Midland, TX (United States)

    1997-08-01

    This paper illustrates how Discrete Fracture Network (DFN) technology can serve as a basis for the calculation of reservoir engineering parameters for the development of fractured reservoirs. It describes the development of quantitative techniques for defining the geometry and volume of structurally controlled compartments. These techniques are based on a combination of stochastic geometry, computational geometry, and graph the theory. The parameters addressed are compartment size, matrix block size and tributary drainage volume. The concept of DFN models is explained and methodologies to compute these parameters are demonstrated.

  16. Nano-scale zero valent iron transport in a variable aperture dolomite fracture and a glass fracture

    Science.gov (United States)

    Mondal, P.; Sleep, B. E.; Cui, Z.; Zhou, Z.

    2014-12-01

    Experiments and numerical simulations are being performed to understand the transport behavior of carboxymethyl cellulose polymer stabilized nano-scale zero valent iron (nZVI) in a variable aperture dolomite rock fracture and a variable aperture glass replica of a fractured slate. The rock fracture was prepared by artificially inducing a fracture in a dolomite block along a stylolite, and the glass fracture was prepared by creating molds with melted glass on two opposing sides of a fractured slate rock block. Both of the fractures were 0.28 m in length and 0.21 m in width. Equivalent hydraulic apertures are about 110 microns for the rock fracture and 250 microns for the glass replica fracture. Sodium bromide and lissamine green B (LGB) serve as conservative tracers in the rock fracture and glass replica fracture, respectively. A dark box set-up with a light source and digital camera is being used to visualize the LGB and CMC-nZVI movement in the glass fracture. Experiments are being performed to determine the effects of water specific discharge and CMC concentration on nZVI transport in the fractures. Transmission electron microscopy, dynamic light scattering, and UV-visual spectrophotometry were performed to determine the stability and characteristics of the CMC-nZVI mixture. The transport of bromide, LGB, CMC, and CMC-nZVI in both fractures is being evaluated through analysis of the effluent concentrations. Time-lapse images are also being captured for the glass fracture. Bromide, LGB, and CMC recoveries have exceeded 95% in both fractures. Significant channeling has been observed in the fractures for CMC transport due to viscous effects.

  17. Clinical effects of internal fixation for ulnar styloid fractures associated with distal radius fractures: A matched case-control study.

    Science.gov (United States)

    Sawada, Hideyoshi; Shinohara, Takaaki; Natsume, Tadahiro; Hirata, Hitoshi

    2016-11-01

    Ulnar styloid fractures are often associated with distal radius fractures. However, controversy exists regarding whether to treat ulnar styloid fractures. This study aimed to evaluate clinical effects of internal fixation for ulnar styloid fractures after distal radius fractures were treated with the volar locking plate system. We used prospectively collected data of distal radius fractures. 111 patients were enrolled in this study. A matched case-control study design was used. We selected patients who underwent fixation for ulnar styloid fractures (case group). Three control patients for each patient of the case group were matched on the basis of age, sex, and fracture type of distal radius fractures from among patients who did not undergo fixation for ulnar styloid fractures (control group). The case group included 16 patients (7 men, 9 women; mean age: 52.6 years; classification of ulnar styloid fractures: center, 3; base, 11; and proximal, 2). The control group included 48 patients (15 men, 33 women; mean age: 61.1 years; classification of ulnar styloid fractures: center, 10; base, 31; and proximal, 7). For radiographic examination, the volar tilt angle, radial inclination angle, and ulnar variance length were measured, and the union of ulnar styloid fractures was judged. For clinical examination, the range of motions, grip strength, Hand20 score, and Numeric Rating Scale score were evaluated. There was little correction loss for each radiological parameter of fracture reduction, and these parameters were not significantly different between the groups. The bone-healing rate of ulnar styloid fractures was significantly higher in the case group than in the control group, but the clinical results were not significantly different. We revealed that there was no need to fix ulnar styloid fractures when distal radius fractures were treated via open reduction and internal fixation with a volar locking plate system. Copyright © 2016 The Japanese Orthopaedic Association

  18. Hip fracture in hospitalized medical patients.

    Science.gov (United States)

    Zapatero, Antonio; Barba, Raquel; Canora, Jesús; Losa, Juan E; Plaza, Susana; San Roman, Jesús; Marco, Javier

    2013-01-08

    The aim of the present study is to analyze the incidence of hip fracture as a complication of admissions to internal medicine units in Spain. We analyzed the clinical data of 2,134,363 adults who had been admitted to internal medicine wards. The main outcome was a diagnosis of hip fracture during hospitalization.Outcome measures included rates of in-hospital fractures, length of stay and cost. A total of 1127 (0.057%) admittances were coded with an in-hospital hip fracture. In hospital mortality rate was 27.9% vs 9.4%; p patients with a hip fracture (20.7 days vs 9.8 days; p patients (6927€ per hospitalization vs 3730€ in non fracture patients). Risk factors related to fracture were: increasing age by 10 years increments (OR 2.32 95% CI 2.11-2.56), female gender (OR 1.22 95% CI 1.08-1.37), admission from nursing home (OR 1.65 95% CI 1.27-2.12), dementia (1.55 OR 95% CI1.30-1.84), malnutrition (OR 2.50 95% CI 1.88-3.32), delirium (OR 1.57 95% CI 1.16-2.14), and anemia (OR 1.30 95%CI 1.12-1.49). In-hospital hip fracture notably increased mortality during hospitalization, doubling the mean length of stay and mean cost of admission. These are reasons enough to stress the importance of designing and applying multidisciplinary plans focused on reducing the incidence of hip fractures in hospitalized patients.

  19. Effect of Natural Fractures on Hydraulic Fracturing

    Science.gov (United States)

    Ben, Y.; Wang, Y.; Shi, G.

    2012-12-01

    Hydraulic Fracturing has been used successfully in the oil and gas industry to enhance oil and gas production in the past few decades. Recent years have seen the great development of tight gas, coal bed methane and shale gas. Natural fractures are believed to play an important role in the hydraulic fracturing of such formations. Whether natural fractures can benefit the fracture propagation and enhance final production needs to be studied. Various methods have been used to study the effect of natural fractures on hydraulic fracturing. Discontinuous Deformation Analysis (DDA) is a numerical method which belongs to the family of discrete element methods. In this paper, DDA is coupled with a fluid pipe network model to simulate the pressure response in the formation during hydraulic fracturing. The focus is to study the effect of natural fractures on hydraulic fracturing. In particular, the effect of rock joint properties, joint orientations and rock properties on fracture initiation and propagation will be analyzed. The result shows that DDA is a promising tool to study such complex behavior of rocks. Finally, the advantages of disadvantages of our current model and future research directions will be discussed.

  20. Fracture channel waves

    Science.gov (United States)

    Nihei, Kurt T.; Yi, Weidong; Myer, Larry R.; Cook, Neville G. W.; Schoenberg, Michael

    1999-03-01

    The properties of guided waves which propagate between two parallel fractures are examined. Plane wave analysis is used to obtain a dispersion equation for the velocities of fracture channel waves. Analysis of this equation demonstrates that parallel fractures form an elastic waveguide that supports two symmetric and two antisymmetric dispersive Rayleigh channel waves, each with particle motions and velocities that are sensitive to the normal and tangential stiffnesses of the fractures. These fracture channel waves degenerate to shear waves when the fracture stiffnesses are large, to Rayleigh waves and Rayleigh-Lamb plate waves when the fracture stiffnesses are low, and to fracture interface waves when the fractures are either very closely spaced or widely separated. For intermediate fracture stiffnesses typical of fractured rock masses, fracture channel waves are dispersive and exhibit moderate to strong localization of guided wave energy between the fractures. The existence of these waves is examined using laboratory acoustic measurements on a fractured marble plate. This experiment confirms the distinct particle motion of the fundamental antisymmetric fracture channel wave (A0 mode) and demonstrates the ease with which a fracture channel wave can be generated and detected.

  1. Traumatic thoracolumbar spine fractures

    NARCIS (Netherlands)

    J. Siebenga (Jan)

    2013-01-01

    textabstractTraumatic spinal fractures have the lowest functional outcomes and the lowest rates of return to work after injury of all major organ systems.1 This thesis will cover traumatic thoracolumbar spine fractures and not osteoporotic spine fractures because of the difference in fracture

  2. The Fracture Process of Tempered Soda-Lime-Silica Glass

    DEFF Research Database (Denmark)

    Nielsen, Jens Henrik; Olesen, John Forbes; Stang, Henrik

    2009-01-01

    This work presents experimental observations of the characteristic fracture process of tempered glass. Square specimens with a side length of 300 mm, various thicknesses and a residual stress state characterized by photoelastic measurements were used. Fracture was initiated using a 2.5 mm diamond...

  3. Fracture of the neck of the femur after radiotherapy

    Energy Technology Data Exchange (ETDEWEB)

    Gantscheff, M.; Wassilew, T.; Tantschew, P. (Meditsinska Akademiya, Sofia (Bulgaria))

    1983-02-01

    Several etiopathogenetic factors of the femoral neck fracture after radiotherapy are discussed taking extensive references into consideration. Results are described paying special attention to the discongruence of the hip joint existing in this fracture. The change of the volume of the femoral head, which can be considered as a consecutive symptom of some vascular lesions, leads to pathologic conditions in the biomechanics of the hip joint causing a special kind of stress fracture.

  4. Assessment of fracture risk

    Energy Technology Data Exchange (ETDEWEB)

    Kanis, John A. [WHO Collaborating Centre for Metabolic Bone Diseases, University of Sheffield Medical School, Beech Hill Road, Sheffield S10 2RX (United Kingdom)], E-mail: w.j.pontefract@sheffield.ac.uk; Johansson, Helena; Oden, Anders [WHO Collaborating Centre for Metabolic Bone Diseases, University of Sheffield Medical School, Beech Hill Road, Sheffield S10 2RX (United Kingdom); McCloskey, Eugene V. [WHO Collaborating Centre for Metabolic Bone Diseases, University of Sheffield Medical School, Beech Hill Road, Sheffield S10 2RX (United Kingdom); Osteoporosis Centre, Northern General Hospital, Sheffield (United Kingdom)

    2009-09-15

    Fractures are a common complication of osteoporosis. Although osteoporosis is defined by bone mineral density at the femoral neck, other sites and validated techniques can be used for fracture prediction. Several clinical risk factors contribute to fracture risk independently of BMD. These include age, prior fragility fracture, smoking, excess alcohol, family history of hip fracture, rheumatoid arthritis and the use of oral glucocorticoids. These risk factors in conjunction with BMD can be integrated to provide estimates of fracture probability using the FRAX tool. Fracture probability rather than BMD alone can be used to fashion strategies for the assessment and treatment of osteoporosis.

  5. Estimating the hydraulic conductivity of two-dimensional fracture networks

    Science.gov (United States)

    Leung, C. T.; Zimmerman, R. W.

    2010-12-01

    Most oil and gas reservoirs, as well as most potential sites for nuclear waste disposal, are naturally fractured. In these sites, the network of fractures will provide the main path for fluid to flow through the rock mass. In many cases, the fracture density is so high as to make it impractical to model it with a discrete fracture network (DFN) approach. For such rock masses, it would be useful to have recourse to analytical, or semi-analytical, methods to estimate the macroscopic hydraulic conductivity of the fracture network. We have investigated single-phase fluid flow through stochastically generated two-dimensional fracture networks. The centres and orientations of the fractures are uniformly distributed, whereas their lengths follow either a lognormal distribution or a power law distribution. We have considered the case where the fractures in the network each have the same aperture, as well as the case where the aperture of each fracture is directly proportional to the fracture length. The discrete fracture network flow and transport simulator NAPSAC, developed by Serco (Didcot, UK), is used to establish the “true” macroscopic hydraulic conductivity of the network. We then attempt to match this conductivity using a simple estimation method that does not require extensive computation. For our calculations, fracture networks are represented as networks composed of conducting segments (bonds) between nodes. Each bond represents the region of a single fracture between two adjacent intersections with other fractures. We assume that the bonds are arranged on a kagome lattice, with some fraction of the bonds randomly missing. The conductance of each bond is then replaced with some effective conductance, Ceff, which we take to be the arithmetic mean of the individual conductances, averaged over each bond, rather than over each fracture. This is in contrast to the usual approximation used in effective medium theories, wherein the geometric mean is used. Our

  6. The impact of different aperture distribution models and critical stress criteria on equivalent permeability in fractured rocks

    DEFF Research Database (Denmark)

    Bisdom, Kevin; Bertotti, Giovanni; Nick, Hamid

    2016-01-01

    Predicting equivalent permeability in fractured reservoirs requires an understanding of the fracture network geometry and apertures. There are different methods for defining aperture, based on outcrop observations (power law scaling), fundamental mechanics (sublinear length-aperture scaling...

  7. Particle Swarm Transport in Fracture Networks

    Science.gov (United States)

    Pyrak-Nolte, L. J.; Mackin, T.; Boomsma, E.

    2012-12-01

    Colloidal particles of many types occur in fractures in the subsurface as a result of both natural and industrial processes (e.g., environmental influences, synthetic nano- & micro-particles from consumer products, chemical and mechanical erosion of geologic material, proppants used in gas and oil extraction, etc.). The degree of localization and speed of transport of such particles depends on the transport mechanisms, the chemical and physical properties of the particles and the surrounding rock, and the flow path geometry through the fracture. In this study, we investigated the transport of particle swarms through artificial fracture networks. A synthetic fracture network was created using an Objet Eden 350V 3D printer to build a network of fractures. Each fracture in the network had a rectangular cross-sectional area with a constant depth of 7 mm but with widths that ranged from 2 mm to 11 mm. The overall dimensions of the network were 132 mm by 166 mm. The fracture network had 7 ports that were used either as the inlet or outlet for fluid flow through the sample or for introducing a particle swarm. Water flow rates through the fracture were controlled with a syringe pump, and ranged from zero flow to 6 ml/min. Swarms were composed of a dilute suspension (2% by mass) of 3 μm fluorescent polystyrene beads in water. Swarms with volumes of 5, 10, 20, 30 and 60 μl were used and delivered into the network using a second syringe pump. The swarm behavior was imaged using an optical fluorescent imaging system illuminated by green (525 nm) LED arrays and captured by a CCD camera. For fracture networks with quiescent fluids, particle swarms fell under gravity and remained localized within the network. Large swarms (30-60 μl) were observed to bifurcate at shallower depths resulting in a broader dispersal of the particles than for smaller swarm volumes. For all swarm volumes studied, particle swarms tended to bifurcate at the intersection between fractures. These

  8. Fracture behavior of hybrid composite laminates

    Science.gov (United States)

    Kennedy, J. M.

    1983-01-01

    The tensile fracture behavior of 15 center-notched hybrid laminates was studied. Three basic laminate groups were tested: (1) a baseline group with graphite/epoxy plies, (2) a group with the same stacking sequence but where the zero-deg plies were one or two plies of S-glass or Kevlar, and (3) a group with graphite plies but where the zero-deg plies were sandwiched between layers of perforated Mylar. Specimens were loaded linearly with time; load, far field strain, and crack opening displacement (COD) were monitored. The loading was stopped periodically and the notched region was radiographed to reveal the extent and type of damage (failure progression). Results of the tests showed that the hybrid laminates had higher fracture toughnesses than comparable all-graphite laminates. The higher fracture toughness was due primarily to the larger damage region at the ends of the slit; delamination and splitting lowered the stress concentration in the primary load-carrying plies. A linear elastic fracture analysis, which ignored delamination and splitting, underestimated the fracture toughness. For almost all of the laminates, the tests showed that the fracture toughness increased with crack length. The size of the damage region at the ends of the slit and COD measurements also increased with crack length.

  9. Resistivity soundings and VLF profiles for siting groundwater wells in a fractured basement aquifer in the Arabian Shield, Saudi Arabia

    Science.gov (United States)

    Ammar, A. I.; Kruse, S. E.

    2016-04-01

    Seasonal shortages of groundwater are common in parts of the Arabian Shield, where complex basement hydrogeology can make siting of water wells difficult. To identify optimal production well locations, six 200-400 m-long Very Low Frequency (VLF) electromagnetic traverses and ten Vertical Electrical Soundings (VESes) were run at the western edge of the Arabian Shield near At-Taif town, Saudi Arabia. Here wadi sediments overlie fractured Precambrian basement, which in turn overlies unfractured basement. The fractured basement forms the water supply aquifer. Both VLF and VES data indicate significant lateral heterogeneity in the electrical conductivity of both wadi and basement deposits over lengths scales as small as ∼100 m. VES results correlate closely with data from two wells in the study area. The change in resistivity at the wadi-to-fractured basement contact is relatively subtle, but the transition from low resistivity fractured basement to high resistivity unfractured basement is well resolved. Inferred wadi thicknesses range from 0 to 14 m; the electrically conductive fractured basement extends from wadi down to 12-32 m depth. VES data indicate the fractured basement aquifer thickens progressively to the south in this area. A production well, sited on the basis of the VES analysis, successfully yielded 70m3/day. The relationship between VLF and VES data is complex, suggesting that the terrain is heterogeneous on the scale of the different effective sampling volumes of the two methods, and/or that fracture azimuth is locally heterogeneous. Overall resistivities in this study are similar to those observed at other locations in Saudi Arabia, suggesting these methods may be widely applicable for siting of groundwater wells in the complex basement of the Arabian Shield.

  10. [Periprosthetic Acetabulum Fractures].

    Science.gov (United States)

    Schreiner, A J; Stuby, F; de Zwart, P M; Ochs, B G

    2016-12-01

    In contrast to periprosthetic fractures of the femur, periprosthetic fractures of the acetabulum are rare complications - both primary fractures and fractures in revision surgery. This topic is largely under-reported in the literature; there are a few case reports and no long term results. Due to an increase in life expectancy, the level of patients' activity and the number of primary joint replacements, one has to expect a rise in periprosthetic complications in general and periprosthetic acetabular fractures in particular. This kind of fracture can be intra-, peri- or postoperative. Intraoperative fractures are especially associated with insertion of cementless press-fit acetabular components or revision surgery. Postoperative periprosthetic fractures of the acetabulum are usually related to osteolysis, for example, due to polyethylene wear. There are also traumatic fractures and fractures missed intraoperatively that lead to some kind of insufficiency fracture. Periprosthetic fractures of the acetabulum are treated conservatively if the implant is stable and the fracture is not dislocated. If surgery is needed, there are many possible different surgical techniques and challenging approaches. That is why periprosthetic fractures of the acetabulum should be treated by experts in pelvic surgery as well as revision arthroplasty and the features specific to the patient, fracture and prosthetic must always be considered. Georg Thieme Verlag KG Stuttgart · New York.

  11. Numerical Simulation of the Propagation of Hydraulic and Natural Fracture Using Dijkstra’s Algorithm

    Directory of Open Access Journals (Sweden)

    Yanfang Wu

    2016-07-01

    Full Text Available Utilization of hydraulic-fracturing technology is dramatically increasing in exploitation of natural gas extraction. However the prediction of the configuration of propagated hydraulic fracture is extremely challenging. This paper presents a numerical method of obtaining the configuration of the propagated hydraulic fracture into discrete natural fracture network system. The method is developed on the basis of weighted fracture which is derived in combination of Dijkstra’s algorithm energy theory and vector method. Numerical results along with experimental data demonstrated that proposed method is capable of predicting the propagated hydraulic fracture configuration reasonably with high computation efficiency. Sensitivity analysis reveals a number of interesting observation results: the shortest path weight value decreases with increasing of fracture density and length, and increases with increasing of the angle between fractures to the maximum principal stress direction. Our method is helpful for evaluating the complexity of the discrete fracture network, to obtain the extension direction of the fracture.

  12. Statistical model of fractures and deformations zones for Forsmark. Preliminary site description Forsmark area - version 1.2

    Energy Technology Data Exchange (ETDEWEB)

    La Pointe, Paul R. [Golder Associate Inc., Redmond, WA (United States); Olofsson, Isabelle; Hermanson, Jan [Golder Associates AB, Uppsala (Sweden)

    2005-04-01

    Compared to version 1.1, a much larger amount of data especially from boreholes is available. Both one-hole interpretation and Boremap indicate the presence of high and low fracture intensity intervals in the rock mass. The depth and width of these intervals varies from borehole to borehole but these constant fracture intensity intervals are contiguous and present quite sharp transitions. There is not a consistent pattern of intervals of high fracture intensity at or near to the surface. In many cases, the intervals of highest fracture intensity are considerably below the surface. While some fractures may have occurred or been reactivated in response to surficial stress relief, surficial stress relief does not appear to be a significant explanatory variable for the observed variations in fracture intensity. Data from the high fracture intensity intervals were extracted and statistical analyses were conducted in order to identify common geological factors. Stereoplots of fracture orientation versus depth for the different fracture intensity intervals were also produced for each borehole. Moreover percussion borehole data were analysed in order to identify the persistence of these intervals throughout the model volume. The main conclusions of these analyses are the following: The fracture intensity is conditioned by the rock domain, but inside a rock domain intervals of high and low fracture intensity are identified. The intervals of high fracture intensity almost always correspond to intervals with distinct fracture orientations (whether a set, most often the NW sub-vertical set, is highly dominant, or some orientation sets are missing). These high fracture intensity intervals are positively correlated to the presence of first and second generation minerals (epidote, calcite). No clear correlation for these fracture intensity intervals has been identified between holes. Based on these results the fracture frequency has been calculated in each rock domain for the

  13. Stochastic and fractal analysis of fracture trajectories

    Science.gov (United States)

    Bessendorf, Michael H.

    1987-01-01

    Analyses of fracture trajectories are used to investigate structures that fall between 'micro' and 'macro' scales. It was shown that fracture trajectories belong to the class of nonstationary processes. It was also found that correlation distance, which may be related to a characteristic size of a fracture process, increases with crack length. An assemblage of crack trajectory processes may be considered as a diffusive process. Chudnovsky (1981-1985) introduced a 'crack diffusion coefficient' d which reflects the ability of the material to deviate the crack trajectory from the most energetically efficient path and thus links the material toughness to its structure. For the set of fracture trajectories in AISI 304 steel, d was found to be equal to 1.04 microns. The fractal dimension D for the same set of trajectories was found to be 1.133.

  14. Elastocapillary Deformations and Fracture of Soft Gels

    Science.gov (United States)

    Daniels, Karen; Grzelka, Marion; Bostwick, Joshua

    When a droplet is placed on the surface of a soft gel, the surface deforms by an amount proportional to the elastocapillary length calculated from the ratio of surface tension and elastic modulus. For sufficiently large deformations, the gel can fracture due to the forces generated under the liquid-gel contact line. We observe that a starburst of channel fractures forms at the surface of the gel, driven by fluid propagating away from the central droplet. To understand the initiation of these cracks, we model the substrate as an incompressible, linear-elastic solid and quantify the elastic response. This provides quantitative agreement with experimental measurements of the number of fracture arms as a function of material properties and geometric parameters. In addition, we find that the initiation process is thermally-activated, with delay time that decreases as a function of the elastocapillary length.

  15. Imaging of vertebral fractures

    Directory of Open Access Journals (Sweden)

    Ananya Panda

    2014-01-01

    Full Text Available Vertebral fracture is a common clinical problem. Osteoporosis is the leading cause of non-traumatic vertebral fracture. Often, vertebral fractures are not clinically suspected due to nonspecific presentation and are overlooked during routine interpretation of radiologic investigations. Moreover, once detected, many a times the radiologist fails to convey to the clinician in a meaningful way. Hence, vertebral fractures are a constant cause of morbidity and mortality. Presence of vertebral fracture increases the chance of fracture in another vertebra and also increases the risk of subsequent hip fracture. Early detection can lead to immediate therapeutic intervention improving further the quality of life. So, in this review, we wish to present a comprehensive overview of vertebral fracture imaging along with an algorithm of evaluation of vertebral fractures.

  16. Assessment of the Impacts of Hydraulic Fracturing at Bakken on Regional Water Resources

    Science.gov (United States)

    Lin, Z.; Lin, T.; Lim, S.; Borders, M.

    2015-12-01

    Unconventional oil production at the Bakken Shale of western North Dakota increased more than ten-fold from 2008 to 2014. Although unconventional oil production uses less water than conventional oil production per unit of energy, the cumulative water needs for unconventional oil production due to multiple drilling and fracturing operations may be locally or temporally significant. We collected and analyzed the data for a total of 8453 horizontal wells developed at Bakken in western North Dakota during 2007-2014. The hydraulic fracturing activities mainly occurred in a core area of four counties, including Dunn, McKenzie, Mountrail, and Williams. The annual total water used for hydraulic fracking in western North Dakota increased from 302 ac-ft in 2007 to 21,605 ac-ft in 2014, by more than 70 times in 8 years. The four-county core area accounted for about 90% of total hydraulic fracturing water use in western North Dakota. Compared to the total water uses of all types, hydraulic fracturing water use in the four-county core area accounted for 0.7% in 2007 and 43.1% in 2014. Statewide, this percentage increased from 0.1% to 6.1% in the same time period. As horizontal drilling and hydraulic fracturing technologies matured for unconventional oil development at Bakken, the total depth and the total length of laterals per well seemed to reach an optimal value in the last four years (2011-2014). However, the number of fracturing stages and the volume of fracking water used per completion are still on the rise. The average water use per well increased from about 1.7 ac-ft in 2007 to 11.4 ac-ft in 2014. Correspondingly, the water intensity (volume of fracking water used per foot of laterals) increased from 67 gallon/ft in 2007 to about 372 gallon/ft 2014. The results helped us better understand the environmental impacts of hydraulic fracturing at Bakken and better manage the water resources in the region.

  17. Patient characteristics and outcomes of a hip fracture and concomitant fracture compared with hip fracture alone: results from a United Kingdom teaching hospital.

    Science.gov (United States)

    Ong, Terence; Anand, Varun; Tan, Wei; Quah, Edmund; Moran, Chris; Sahota, Opinder

    2016-04-01

    A proportion of patients sustaining hip fractures present with a concomitant fracture. We aimed to evaluate the relationship between patient characteristics and clinical outcomes, in those with a hip and concomitant fracture compared with those sustaining a hip fracture alone from a clinical service registry. Cross-sectional study using data obtained from a clinical service registry (Nottingham Hip Fracture Database) on patients aged 50 and above who suffered a hip fracture between 1/1/2003 and 31/12/2012. Data was collected on patient demographics, fracture information and healthcare outcomes. 7338 patients of which 75 % were female (mean age 82 (SD 9.4), had a hip fracture with 334 (4.6 %) patients having a concomitant fracture. The majority (58 %) were distal radius or proximal humeral fractures. Only females (p = 0.002), those taking three or fewer medications (p = 0.018) and those on long term steroids (p = 0.048) were more likely to suffer a concomitant fracture. There was no difference in mortality, rates of postoperative complication, intensive care unit or care home admission between both groups. Patients with a concomitant fracture have a 16 % longer average length of stay in hospital (mean difference 1.16; 95 % CI 1.07-1.25, p fractures have similar patient characteristics, except gender, polypharmacy and long term steroid use; and outcomes to those presenting with hip fracture alone, except a longer average inpatient stay.

  18. A comparison of bone density and bone morphology between patients presenting with hip fractures, spinal fractures or a combination of the two.

    Science.gov (United States)

    Crilly, Richard G; Cox, Lizebeth

    2013-02-22

    Currently it is uncertain how to define osteoporosis and who to treat after a hip fracture. There is little to support the universal treatment of all such patients but how to select those most in need of treatment is not clear. In this study we have compared cortical and trabecular bone status between patients with spinal fractures and those with hip fracture with or without spinal fracture with the aim to begin to identify, by a simple clinical method (spine x-ray), a group of hip fracture patients likely to be more responsive to treatment with current antiresorptive agents. Comparison of convenience samples of three groups of 50 patients, one with spinal fractures, one with a hip fracture, and one with both. Measurements consist of bone mineral density at the lumbar spine, at the four standard hip sites, number, distribution and severity of spinal fractures by the method of Genant, cortical bone thickness at the infero-medial femoral neck site, femoral neck and axis length and femoral neck width. Patients with spinal fractures alone have the most deficient bones at both trabecular and cortical sites: those with hip fracture and no spinal fractures the best at trabecular bone and most cortical bone sites: and those with both hip and spinal fractures intermediate in most measurements. Hip axis length and neck width did not differ between groups. The presence of the spinal fracture indicates poor trabecular bone status in hip fracture patients. Hip fracture patients without spinal fractures have a bone mass similar to the reference range for their age and gender. Poor trabecular bone in hip fracture patients may point to a category of patient more likely to benefit from therapy and may be indicated by the presence of spinal fractures.

  19. Smart magnetic markers use in hydraulic fracturing.

    Science.gov (United States)

    Zawadzki, Jarosław; Bogacki, Jan

    2016-11-01

    One of the main challenges and unknowns during shale gas exploration is to assess the range and efficiency of hydraulic fracturing. It is also essential to assess the distribution of proppant, which keeps the fracture pathways open. Solving these problems may considerably increase the efficiency of the shale gas extraction. Because of that, the idea of smart magnetic marker, which can be detected when added to fracturing fluid, has been considered for a long time. This study provides overview of the possibilities of magnetic marker application for shale gas extraction. The imaging methods using electromagnetic markers, are considered or developed in two directions. The first possibility is the markers' electromagnetic activity throughout the whole volume of the fracturing fluid. Thus, it can be assumed that the whole fracturing fluid is the marker. Among these type of hydraulic fracturing solutions, ferrofluid could be considered. The second possibility is marker, which is just one of many components of the fracturing fluid. In this case feedstock magnetic materials, ferrites and nanomaterials could be considered. Magnetic properties of magnetite could be too low and ferrofluids' or nanomaterials' price is unacceptably high. Because of that, ferrites, especially ZnMn ferrites seems to be the best material for magnetic marker. Because of the numerous applications in electronics, it is cheap and easily available, although the price is higher, then that of magnetite. The disadvantage of using ferrite, could be too small mechanical strength. It creates an essential need for combining magnetic marker with proppant into magnetic-ceramic composite.

  20. Fracture Criterion for Fracture Mechanics of Magnets

    Institute of Scientific and Technical Information of China (English)

    潘灏; 杨文涛

    2003-01-01

    The applicability and limitation of some fracture criteria in the fracture mechanics of magnets are studied.It is shown that the magnetic field intensity factor can be used as a fracture criterion when the crack in a magnet is only affected by a magnetic field. For some magnetostrictive materials in which the components of magnetostriction strain do not satisfy the compatibility equation of deformation, the stress intensity factor can no longer be effectively applicable as a fracture criterion when the crack in a magnet is affected by a magnetic field and mechanical loads simultaneously.

  1. Fracture of anisotropic materials with plastic strain-gradient effects

    DEFF Research Database (Denmark)

    Legarth, Brian Nyvang

    2013-01-01

    parameter is adopted. The fracture process along the fiber-matrix interface is modeled using a recently proposed cohesive law extension having an additional material length parameter. Due to the fiber-matrix fracture a sudden stress-drop is seen in the macroscopic stress-strain response which defines......A unit cell is adopted to numerically analyze the effect of plastic anisotropy on frac-ture evolution in a micro-reinforced fiber-composite. The matrix material exhibit size-effects and an anisotropic strain-gradient plasticity model accounting for such size-effects through a mate-rial length scale...... the failure strain of the composite. The effect of the two material length parameters on the failure strain of the composite is studied. For small values of the material length scale parameter conventional predictions are obtained. Larger values of the material length scale parameter result in corresponding...

  2. Comparison of fracture properties of cellulose nanopaper, printing paper and buckypaper

    DEFF Research Database (Denmark)

    Mao, Rui; Goutianos, Stergios; Tu, Wei-Chen

    2017-01-01

    -fibre bonding. The aim of this paper is to investigate the fracture properties of cellulose nanopaper using double edge notch tensile tests on samples with different notch lengths. It was found that strength is insensitive to notch length. A cohesive zone model was used to describe the fracture behaviour...

  3. Fractal modeling of natural fracture networks. Final report, June 1994--June 1995

    Energy Technology Data Exchange (ETDEWEB)

    Ferer, M.V.; Dean, B.H.; Mick, C.

    1996-04-01

    Recovery from naturally fractured, tight-gas reservoirs is controlled by the fracture network. Reliable characterization of the actual fracture network in the reservoir is severely limited. The location and orientation of fractures intersecting the borehole can be determined, but the length of these fractures cannot be unambiguously determined. Fracture networks can be determined for outcrops, but there is little reason to believe that the network in the reservoir should be identical because of the differences in stresses and history. Because of the lack of detailed information about the actual fracture network, modeling methods must represent the porosity and permeability associated with the fracture network, as accurately as possible with very little apriori information. Three rather different types of approaches have been used: (1) dual porosity simulations; (2) `stochastic` modeling of fracture networks, and (3) fractal modeling of fracture networks. Stochastic models which assume a variety of probability distributions of fracture characteristics have been used with some success in modeling fracture networks. The advantage of these stochastic models over the dual porosity simulations is that real fracture heterogeneities are included in the modeling process. In the sections provided in this paper the authors will present fractal analysis of the MWX site, using the box-counting procedure; (2) review evidence testing the fractal nature of fracture distributions and discuss the advantages of using their fractal analysis over a stochastic analysis; (3) present an efficient algorithm for producing a self-similar fracture networks which mimic the real MWX outcrop fracture network.

  4. The Shear Mechanisms of Natural Fractures during the Hydraulic Stimulation of Shale Gas Reservoirs

    Directory of Open Access Journals (Sweden)

    Zhaobin Zhang

    2016-08-01

    Full Text Available The shearing of natural fractures is important in the permeability enhancement of shale gas reservoirs during hydraulic fracturing treatment. In this work, the shearing mechanisms of natural fractures are analyzed using a newly proposed numerical model based on the displacement discontinuities method. The fluid-rock coupling system of the model is carefully designed to calculate the shearing of fractures. Both a single fracture and a complex fracture network are used to investigate the shear mechanisms. The investigation based on a single fracture shows that the non-ignorable shearing length of a natural fracture could be formed before the natural fracture is filled by pressurized fluid. Therefore, for the hydraulic fracturing treatment of the naturally fractured shale gas reservoirs, the shear strength of shale is generally more important than the tensile strength. The fluid-rock coupling propagation processes of a complex fracture network are simulated under different crustal stress conditions and the results agree well with those of the single fracture. The propagation processes of complex fracture network show that a smaller crustal stress difference is unfavorable to the shearing of natural fractures, but is favorable to the formation of complex fracture network.

  5. Influence of irradiation on the ductile fracture of a reactor pressure vessel steel

    Science.gov (United States)

    Haušild, Petr; Kytka, Miloš; Karlík, Miroslav; Pešek, Pavel

    2005-05-01

    The mechanical properties of 15Ch2MFA steel were characterised by tensile and instrumented Charpy tests. The fracture surfaces of Charpy specimens broken in the ductile-to-brittle transition temperature range contain a certain proportion of ductile fracture correlated to fracture energy. Measured ductile crack lengths show the same dependence on fracture deflection and/or fracture energy for irradiated and non-irradiated specimens. The decrease of upper shelf energy with increasing neutron fluence could be explained by an increasing amount of shear fracture.

  6. Traumatic Vertebral Fractures and Concomitant Fractures of the Rib in Southwest China, 2001 to 2010

    Science.gov (United States)

    Wang, Hongwei; Zhou, Yue; Ou, Lan; Li, Changqing; Liu, Jun; Xiang, Liangbi

    2015-01-01

    Abstract To our knowledge, the clinical characteristics of traumatic vertebral fractures and concomitant fractures of the rib (TVF-RF) have not been described in previous studies. To investigate the clinical characteristics of patients managed for TVF-RF. A retrospective study of 3142 patients who presented with traumatic vertebral fractures was performed. Two hundred twenty-six patients (7.2%) suffered from TVF-RF. Incidence rate ratios were then calculated with respect to the level of injury to the spine, the ASIA classification of neurological deficits and age. There were 171 male (75.7%) and 55 female (24.3%) patients with a mean age of 43.8 years. The most common mechanisms were falls from high heights in 81 cases and road traffic crashes in 67 cases. Right-sided rib injury occurred in 106 cases, left-sided injury occurred in 76 cases, and bilateral injury occurred in 44 cases. The most frequent location of the rib fractures was from the fourth rib to the ninth rib (70.3%, 510/725). Initial pulmonary complications (IPC) after trauma occurred in 116 cases (51.3%). The mortality rate for the entire group was 1.3% (3/226). The patients with thoracic vertebral fractures and neurological deficits had a higher frequency of multiple rib fractures and IPC than the other patients (P rib fractures, the frequency of IPC and mean intensive care unit (ICU) length of stay also increased. The rates of complications for patients with rib fractures were significantly different from those without rib fractures. We should pay much attention to the patients who presented with thoracic vertebral fractures and neurological deficits for minimizing further complications and mortality in such patients who had a higher frequency of multiple rib fractures and IPC than the other patients. PMID:26554809

  7. Minimum Length - Maximum Velocity

    CERN Document Server

    Panes, Boris

    2011-01-01

    We study a framework where the hypothesis of a minimum length in space-time is complemented with the notion of reference frame invariance. It turns out natural to interpret the action of the obtained reference frame transformations in the context of doubly special relativity. As a consequence of this formalism we find interesting connections between the minimum length properties and the modified velocity-energy relation for ultra-relativistic particles. For example we can predict the ratio between the minimum lengths in space and time using the results from OPERA about superluminal neutrinos.

  8. Eruption versus intrusion? Arrest of propagation of constant volume, buoyant, liquid-filled cracks in an elastic, brittle host

    Science.gov (United States)

    Taisne, B.; Tait, S.

    2009-06-01

    When a volume of magma is released from a source at depth, one key question is whether or not this will culminate in an eruption or in the emplacement of a shallow intrusion. We address some of the physics behind this question by describing and interpreting laboratory experiments on the propagation of cracks filled with fixed volumes of buoyant liquid in a brittle, elastic host. Experiments were isothermal, and the liquid was incompressible. The cracks propagated vertically because of liquid buoyancy but were then found to come to a halt at a configuration of static mechanical equilibrium, a result that is inconsistent with the prediction of the theory of linear elastic fracture mechanics in two dimensions. We interpret this result as due to a three-dimensional effect. At the curved crack front, horizontal cracking is necessary in order for vertical propagation to take place. As the crack elongates and thins, the former becomes progressively harder and, in the end, impossible to fracture. We present a scaling law for the final length and breadth of cracks as a function of a governing dimensionless parameter, constructed from the liquid volume, the buoyancy, and host fracture toughness. An important implication of this result is that a minimum volume of magma is required for a volcanic eruption to occur for a given depth of magma reservoir.

  9. Low-intensity pulsed ultrasound increases bone volume, osteoid thickness and mineral apposition rate in the area of fracture healing in patients with a delayed union of the osteotomized fibula

    NARCIS (Netherlands)

    Rutten, S.; Nolte, P.A.; Korstjens, C.M.; van Duin, M.A.; Klein-Nulend, J.

    2008-01-01

    Introduction Low-intensity pulsed ultrasound (LIPUS) accelerates impaired fracture healing, but the exact mechanism is unknown. The aim of this study was to investigate how LIPUS affects bone healing at the tissue level in patients with a delayed union of the osteotomized fibula, by using histology

  10. On Estimation of Fracture Aperture with Ground Penetrating Radar

    Science.gov (United States)

    Linde, N.; Shakas, A.

    2016-12-01

    Ground penetrating radar (GPR) is an excellent tool for fracture imaging, but GPR-assisted estimation of fracture aperture is a largely unresolved challenge. The main reason for this is that traditional modeling techniques face severe limitations in fractured rock environments. For example, finite-difference time-domain (FDTD) formulations of Maxwell's equations are poorly adapted to deal with fractures of arbitrary orientations and apertures that are three-five orders of magnitude smaller than the modeling domain. An alternative is to use analytical solutions for thin-bed responses, but they are based on strong assumptions that often do not apply in practise. We have recently developed an efficient modeling approach to simulate GPR propagation and reflection in fractured rock. Here, we first use this modeling formulation to examine the ability of the thin-bed solution to infer the aperture of a homogeneous fracture. We then consider a suite of synthetic examples with heterogeneous fracture aperture fields of varying fractal (Hurst) exponents and spatial correlation lengths. We then use a global optimization algorithm to infer a mean (effective) fracture aperture in each case using the noise-contaminated synthetic data. The thin-bed solution leads to biased aperture estimates even if the fracture has a constant aperture and all other modeling parameters are known. With our modeling approach, we find that appropriate mean apertures are estimated in the homogeneous case, and when the correlation length of the aperture distribution is of similar scale (or larger) than the dominant GPR wavelength.

  11. The Behaviour of Fracture Growth in Sedimentary Rocks: A Numerical Study Based on Hydraulic Fracturing Processes

    Directory of Open Access Journals (Sweden)

    Lianchong Li

    2016-03-01

    Full Text Available To capture the hydraulic fractures in heterogeneous and layered rocks, a numerical code that can consider the coupled effects of fluid flow, damage, and stress field in rocks is presented. Based on the characteristics of a typical thin and inter-bedded sedimentary reservoir, China, a series of simulations on the hydraulic fracturing are performed. In the simulations, three points, i.e., (1 confining stresses, representing the effect of in situ stresses, (2 strength of the interfaces, and (3 material properties of the layers on either side of the interface, are crucial in fracturing across interfaces between two adjacent rock layers. Numerical results show that the hydrofracture propagation within a layered sequence of sedimentary rocks is controlled by changing in situ stresses, interface properties, and lithologies. The path of the hydraulic fracture is characterized by numerous deflections, branchings, and terminations. Four types of potential interaction, i.e., penetration, arrest, T-shaped branching, and offset, between a hydrofracture and an interface within the layered rocks are formed. Discontinuous composite fracture segments resulting from out-of-plane growth of fractures provide a less permeable path for fluids, gas, and oil than a continuous planar composite fracture, which are one of the sources of the high treating pressures and reduced fracture volume.

  12. Optimization of Multi-Cluster Fracturing Model under the Action of Induced Stress in Horizontal Wells

    Directory of Open Access Journals (Sweden)

    Shanyong Liu

    2016-05-01

    Full Text Available Volume fracturing in shale gas forms complex fracture networks and increases stimulated reservoir volume through large-scale fracturing operation with plug-perforation technology. However, some perforation clusters are stimulated unevenly after fracturing. This study aims to solve this problem by analyzing the shortcomings of the conventional fracturing model and developing a coupled model based on the 2D fracture motion equation, energy conservation law, linear elastic mechanics, and stress superposition principle. First, a multi-fracture in-situ stress model was built by studying the induced stress produced by the fracture initiation to deduce the multi-fracture induced stress impact factor on the basis of the stress superposition principle. Then, the classical Perkins–Kern–Nordgren model was utilized with the crustal stress model. Finally, a precise fracturing design method was used to optimize perforation and fracturing parameters under the new model. Results demonstrate that the interference effect among fractures is the major factor causing the non-uniform propagation of each fracture. Compression on the main horizontal stress increases the net pressure. Therefore, both the degree of operation difficulty and the complexity of fracture geometry are improved. After applying the optimal design, the production is increased by 20%, and the cost is reduced by 15%.

  13. Dosimetric Comparison Between VMAT and IMRT for Different Tumor Volume and Different Lesion Length of E-sophageal Cancer%VMAT与IMRT在不同瘤体体积和瘤体长度食管癌中的剂量学比较

    Institute of Scientific and Technical Information of China (English)

    杨瑜; 刘丽虹; 韩春; 王澜; 田华

    2015-01-01

    Objective To compare the dosimetric differences between volumetric modulated arc therapy ( VMAT ) and static intensity modulated radiotherapy ( IMRT) for different tumor volume and different lesion length of esophageal cancer. Meth-ods The Elekta Oncentra4. 1 Planning System was adopted to design both VMAT and IMRT plans for fifty patients who were diag-nosed with thoracic esophageal cancer. All treatment plans of the 50 cases were evaluated using the dose-volume histogram parame-ters of PTV and the organs at risk. The monitor units (MUs) were Also examined. Results ①For GTV volume55cm 3 group. ②For lesion length9cm group,VMAT plan achieved lower D90 and V100, whereas HI and CI were not significantly different.③For GTV vol-ume9cm group, VMAT plan resulted in a slightly lower lung V10 and higher lung V30. For GTV volume>55cm 3 group,VMAT plan resulted in a lower lung V10. For 5~9cm group,sparing of lungs showed no statistically significant differences between the two techniques.④The Dmean of heart in VMAT plan was not statistically different in comparison with IMRT plan for GTV volume>55cm 3 group and lesion length>9cm group, but higher than in IMRT for GTV volume55cm 3 group, and by an average of 16. 1% and 16. 0% in the 5~9cm group and >9cm group. However, VMAT plan provided an aver-age of 10. 4% and 14. 4% more monitor units than IMRT plan in the volume55cm3组, VMAT PTVV100低于IMRT。②GTV长度9cm组,VMAT D90、V100低于IMRT,HI和CI无明显差异。③体积9cm组,VMAT肺V10降低,V30增高;体积>55cm 3组,VMAT肺V10低于IMRT;长度5~9cm组,两种计划差异无统计学意义。④GTV体积55cm 3和长度>9cm组两种计划心脏受量相似。脊髓Dmax两种计划比较差异无统计学意义。⑤在机器调数( MU)方面GTV体积15~55cm 3和>55cm 3组及GTV长度5~9cm和>9cm组,VMAT的MU较IMRT分别减少11.3%、18.1%、16.1%和16.0%。而体积<15cm3和长度<5cm组,VMAT的MU则分别增加了10.4%和14.4%。结论在

  14. Hydraulic fracturing water use variability in the United States and potential environmental implications

    OpenAIRE

    Gallegos, Tanya J.; Varela, Brian A.; Haines, Seth S.; Engle, Mark A.

    2015-01-01

    Abstract Until now, up‐to‐date, comprehensive, spatial, national‐scale data on hydraulic fracturing water volumes have been lacking. Water volumes used (injected) to hydraulically fracture over 263,859 oil and gas wells drilled between 2000 and 2014 were compiled and used to create the first U.S. map of hydraulic fracturing water use. Although median annual volumes of 15,275 m3 and 19,425 m3 of water per well was used to hydraulically fracture individual horizontal oil and gas wells, respecti...

  15. Telomere length and depression

    DEFF Research Database (Denmark)

    Wium-Andersen, Marie Kim; Ørsted, David Dynnes; Rode, Line

    2016-01-01

    BACKGROUND: Depression has been cross-sectionally associated with short telomeres as a measure of biological age. However, the direction and nature of the association is currently unclear. AIMS: We examined whether short telomere length is associated with depression cross-sectionally as well...... as prospectively and genetically. METHOD: Telomere length and three polymorphisms, TERT, TERC and OBFC1, were measured in 67 306 individuals aged 20-100 years from the Danish general population and associated with register-based attendance at hospital for depression and purchase of antidepressant medication....... RESULTS: Attendance at hospital for depression was associated with short telomere length cross-sectionally, but not prospectively. Further, purchase of antidepressant medication was not associated with short telomere length cross-sectionally or prospectively. Mean follow-up was 7.6 years (range 0...

  16. Relating Cohesive Zone Model to Linear Elastic Fracture Mechanics

    Science.gov (United States)

    Wang, John T.

    2010-01-01

    The conditions required for a cohesive zone model (CZM) to predict a failure load of a cracked structure similar to that obtained by a linear elastic fracture mechanics (LEFM) analysis are investigated in this paper. This study clarifies why many different phenomenological cohesive laws can produce similar fracture predictions. Analytical results for five cohesive zone models are obtained, using five different cohesive laws that have the same cohesive work rate (CWR-area under the traction-separation curve) but different maximum tractions. The effect of the maximum traction on the predicted cohesive zone length and the remote applied load at fracture is presented. Similar to the small scale yielding condition for an LEFM analysis to be valid. the cohesive zone length also needs to be much smaller than the crack length. This is a necessary condition for a CZM to obtain a fracture prediction equivalent to an LEFM result.

  17. Tibia (Shinbone) Shaft Fractures

    Science.gov (United States)

    ... energy collisions, such as an automobile or motorcycle crash, are common causes of tibial sha fractures. In cases like these, the bone can be broken into several pieces (comminuted fracture). Sports injuries, such as a fall while skiing or running ...

  18. Fractures in anisotropic media

    Science.gov (United States)

    Shao, Siyi

    Rocks may be composed of layers and contain fracture sets that cause the hydraulic, mechanical and seismic properties of a rock to be anisotropic. Coexisting fractures and layers in rock give rise to competing mechanisms of anisotropy. For example: (1) at low fracture stiffness, apparent shear-wave anisotropy induced by matrix layering can be masked or enhanced by the presence of a fracture, depending on the fracture orientation with respect to layering, and (2) compressional-wave guided modes generated by parallel fractures can also mask the presence of matrix layerings for particular fracture orientations and fracture specific stiffness. This report focuses on two anisotropic sources that are widely encountered in rock engineering: fractures (mechanical discontinuity) and matrix layering (impedance discontinuity), by investigating: (1) matrix property characterization, i.e., to determine elastic constants in anisotropic solids, (2) interface wave behavior in single-fractured anisotropic media, (3) compressional wave guided modes in parallel-fractured anisotropic media (single fracture orientation) and (4) the elastic response of orthogonal fracture networks. Elastic constants of a medium are required to understand and quantify wave propagation in anisotropic media but are affected by fractures and matrix properties. Experimental observations and analytical analysis demonstrate that behaviors of both fracture interface waves and compressional-wave guided modes for fractures in anisotropic media, are affected by fracture specific stiffness (controlled by external stresses), signal frequency and relative orientation between layerings in the matrix and fractures. A fractured layered medium exhibits: (1) fracture-dominated anisotropy when the fractures are weakly coupled; (2) isotropic behavior when fractures delay waves that are usually fast in a layered medium; and (3) matrix-dominated anisotropy when the fractures are closed and no longer delay the signal. The

  19. Sprains, Strains and Fractures

    Science.gov (United States)

    ... Young Physicians Annual Scientific Meeting Webinars Careers in Podiatry APMA 2040 Student Profiles CPME REdRC Manage Your ... and fractures. Many fractures and sprains occur during sports. Football players are particularly vulnerable to foot and ...

  20. Hip fracture - discharge

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/patientinstructions/000168.htm Hip fracture - discharge To use the sharing features on this page, please enable JavaScript. Hip fracture surgery is done to repair a break in ...

  1. Hip fracture surgery

    Science.gov (United States)

    ... neck fracture repair; Trochanteric fracture repair; Hip pinning surgery; Osteoarthritis - hip ... You may receive general anesthesia for this surgery. This means you ... spinal anesthesia . With this kind of anesthesia, medicine is ...

  2. Metatarsal stress fractures - aftercare

    Science.gov (United States)

    ... page: //medlineplus.gov/ency/patientinstructions/000553.htm Metatarsal stress fractures - aftercare To use the sharing features on ... that connect your ankle to your toes. A stress fracture is a break in the bone that ...

  3. Periprosthetic acetabular fractures.

    Science.gov (United States)

    Benazzo, Francesco; Formagnana, Mario; Bargagliotti, Marco; Perticarini, Loris

    2015-10-01

    The aim of this article is to propose a diagnostic and therapeutic algorithm for the acetabular periprosthetic fractures. This article explores the current literature on the epidemiology, causes and classification of periprosthetic acetabular fractures. Integrating data with the experience of the authors, it offers a guide to diagnosis and possible therapeutic strategies. Intra-operative fractures can occur during rasping, reaming or implant impaction, and they must be treated immediately if the component(s) is (are) unstable. Post-operative fractures can be due to major trauma (acute fractures) or minor forces in bone osteolysis; it is possible to plan reconstruction and fixation according to fracture characteristics. Treatment choice depends upon fracture site and implant stability. Periprosthetic acetabular fractures are uncommon complications that can occur intra-operatively or post-operatively, and a reconstructive surgeon must be able to manage the procedure. Accurate planning and reconstruction implant are necessary to achieve good cup stability.

  4. A Characteristic Particle Length

    CERN Document Server

    Roberts, Mark D

    2015-01-01

    It is argued that there are characteristic intervals associated with any particle that can be derived without reference to the speed of light $c$. Such intervals are inferred from zeros of wavefunctions which are solutions to the Schr\\"odinger equation. The characteristic length is $\\ell=\\beta^2\\hbar^2/(8Gm^3)$, where $\\beta=3.8\\dots$; this length might lead to observational effects on objects the size of a virus.

  5. Comparison of femoral morphology and bone mineral density between femoral neck fractures and trochanteric fractures.

    Science.gov (United States)

    Maeda, Yuki; Sugano, Nobuhiko; Saito, Masanobu; Yonenobu, Kazuo

    2011-03-01

    Many studies that analyzed bone mineral density (BMD) and skeletal factors of hip fractures were based on uncalibrated radiographs or dual-energy xray absorptiometry (DXA). Spatial accuracy in measuring BMD and morphologic features of the femur with DXA is limited. This study investigated differences in BMD and morphologic features of the femur between two types of hip fractures using quantitative computed tomography (QCT). Forty patients with hip fractures with normal contralateral hips were selected for this study between 2003 and 2007 (trochanteric fracture, n=18; femoral neck fracture, n=22). Each patient underwent QCT of the bilateral femora using a calibration phantom. Using images of the intact contralateral femur, BMD measurements were made at the point of minimum femoral-neck cross-sectional area, middle of the intertrochanteric region, and center of the femoral head. QCT images also were used to measure morphologic features of the hip, including hip axis length, femoral neck axis length, neck-shaft angle, neck width, head offset, anteversion of the femoral neck, and cortical index at the femoral isthmus. No significant differences were found in trabecular BMD between groups in those three regions. Patients with trochanteric fractures showed a smaller neck shaft angle and smaller cortical index at the femoral canal isthmus compared with patients with femoral neck fractures. We conclude that severe osteoporosis with thinner cortical bone of the femoral diaphysis is seen more often in patients with trochanteric fracture than in patients with femoral neck fracture. Level IV, prognostic study. See Guidelines for Authors for a complete description of levels of evidence.

  6. Stimuli Responsive/Rheoreversible Hydraulic Fracturing Fluids for Enhanced Geothermal Energy Production (Part II)

    Energy Technology Data Exchange (ETDEWEB)

    Bonneville, Alain; Jung, Hun Bok; Shao, Hongbo; Kabilan, Senthil; Um, Wooyong; Carroll, Kenneth C.; Varga, Tamas; Suresh, Niraj; Stephens, Sean A.; Fernandez, Carlos A.

    2014-12-14

    We have used an environmentally friendly and recyclable hydraulic fracturing fluid - diluted aqueous solutions of polyallylamine or PAA – for reservoir stimulation in Enhanced Geothermal System (EGS). This fluid undergoes a controlled and large volume expansion with a simultaneous increase in viscosity triggered by CO2 at EGS temperatures. We are presenting here the results of laboratory-scale hydraulic fracturing experiment using the fluid on small cylindrical rock cores (1.59 cm in diameter and 5.08 cm in length) from the Coso geothermal field in California. Rock samples consisted of Mesozoic diorite metamorphosed to greenschist facies. The experiments were conducted on 5 samples for realistic ranges of pressures (up to 275 bar) and temperatures (up to 210 °C) for both the rock samples and the injected fluid. After fracturing, cores were subjected to a CO2 leakage test, injection of KI solution, and X-ray microtomography (XMT) scanning to examine the formation and distribution of fractures. The design and conduct of these experiments will be presented and discussed in details. Based on the obtained XMT images, Computational Fluid Dynamics (CFD) simulations were then performed to visualize hydraulic fractures and compute the bulk permeability. OpenFOAM (OpenCFD Ltd., Reading, UK), was used to solve the steady state simulation. The flow predictions, based upon the laminar, 3-D, incompressible Navier-Stokes equations for fluid mass and momentum, show the remarkable stimulation of the permeability in the core samples and demonstrate the efficiency of such a CO2 triggered fluid in EGS.

  7. Analysis of pressure data of vertically fractured injection wells

    Energy Technology Data Exchange (ETDEWEB)

    Bennett, C.O.; Reynolds, A.C. Jr.; Raghaven, R.

    1979-06-01

    This study investigates the flowing and shut-in pressure behavior of a fractured well located in a square drainage region with the outer boundary at a constant pressure. The fracture plane lies on one of the diagonals of the square. The results can be used to analyze pressure data for a five-spot pattern when the fracture orientation is most favorable (from the viewpoint of sweep efficiency). Comparisons with the results in the literature (which assume that the fracture orientation is unfavorable) are given. It is shown that the fracture orientation must be considered in the analysis of pressure data for the following conditions: (i) small values of fracture penetration ratio, (ii) large flowing times prior to shut-in, and (iii) large values of fracture flow capacity. New insights into the application of type curve analysis to estimate drainage volumes are presented. The drainage volume can be obtained from a pressure fall-off test only if the flowing times prior to shut-in are large. The estimate of the drainage volume obtained by type curve matching pressure build-up data can be erroneous even if producing times are long. Claims in the literature regarding the determination of the drainage volume by type curve matching appear to be based on unrealistic expectations. The flowing pressures were obtained by a Crank-Nicolson Galerkin procedure. Analytical expressions to evaluate the integrals of the basis functions used in this study are given.

  8. Equilibrium CO bond lengths

    Science.gov (United States)

    Demaison, Jean; Császár, Attila G.

    2012-09-01

    Based on a sample of 38 molecules, 47 accurate equilibrium CO bond lengths have been collected and analyzed. These ultimate experimental (reEX), semiexperimental (reSE), and Born-Oppenheimer (reBO) equilibrium structures are compared to reBO estimates from two lower-level techniques of electronic structure theory, MP2(FC)/cc-pVQZ and B3LYP/6-311+G(3df,2pd). A linear relationship is found between the best equilibrium bond lengths and their MP2 or B3LYP estimates. These (and similar) linear relationships permit to estimate the CO bond length with an accuracy of 0.002 Å within the full range of 1.10-1.43 Å, corresponding to single, double, and triple CO bonds, for a large number of molecules. The variation of the CO bond length is qualitatively explained using the Atoms in Molecules method. In particular, a nice correlation is found between the CO bond length and the bond critical point density and it appears that the CO bond is at the same time covalent and ionic. Conditions which permit the computation of an accurate ab initio Born-Oppenheimer equilibrium structure are discussed. In particular, the core-core and core-valence correlation is investigated and it is shown to roughly increase with the bond length.

  9. Observations on oesophageal length.

    Science.gov (United States)

    Kalloor, G J; Deshpande, A H; Collis, J L

    1976-01-01

    The subject of oesophageal length is discussed. The great variations in the length of the oesophagus in individual patients is noted, and the practical use of its recognition in oesophageal surgery is stressed. An apprasial of the various methods available for this measurement is made; this includes the use of external chest measurement, endoscopic measurement, and the measurement of the level of the electrical mucosal potential change. Correlative studies of these various methods are made, and these show a very high degree of significance. These studies involved simultaneous measurement of external and internal oesophageal length in 26 patients without a hiatal hernia or gastro-oesophageal length in 26 patients without a hiatal hernia or gastro-oesophageal reflux symptoms, 42 patients with sliding type hiatal hernia, and 17 patients with a peptic stricture in association with hiatal hernia. The method of measuring oesophageal length by the use of the external chest measurement, that is, the distance between the lower incisor teeth and the xiphisternum, measured with the neck fully extended and the patient lying supine, is described in detail, its practical application in oesophageal surgery is illustrated, and its validity tested by internal measurements. The findings of this study demonstrate that the external chest measurement provides a mean of assessing the true static length of the oesophagus, corrected for the size of the individual. Images PMID:941114

  10. Identifying osteoporotic vertebral fracture

    OpenAIRE

    Griffith, James F.

    2015-01-01

    Osteoporosis per se is not a harmful disease. It is the sequela of osteoporosis and most particularly the occurrence of osteoporotic fracture that makes osteoporosis a serious medical condition. All of the preventative measures, investigations, treatment and research into osteoporosis have one primary goal and that is to prevent the occurrence of osteoporotic fracture. Vertebral fracture is by far and away the most prevalent osteoporotic fracture. The significance and diagnosis of vertebral f...

  11. Fracture development in shale and its relationship to gas accumulation

    Directory of Open Access Journals (Sweden)

    Wenlong Ding

    2012-01-01

    Full Text Available Shale with high quartz, feldspar and carbonate, will have low Poisson’s ratio, high Young’s modulus and high brittleness. As a result, the shale is conducive to produce natural and induced fractures under external forces. In general, there is a good correlation between fracture development in shale and the volume of brittle minerals present. Shale with high TOC or abnormally high pressure has well-developed fractures. Shale fracture development also shows a positive correlation with total gas accumulation and free gas volume, i.e., the better shale fractures are developed, the greater the gas accumulation and therefore the higher the gas production. Fractures provide migration conduits and accumulation spaces for natural gas and formation water, which are favorable for the volumetric increase of free natural gas. Wider fractures in shale result in gas loss. In North America, there is a high success ratio of shale gas exploration and high gas production from high-angle fracture zones in shale. Good natural gas shows or low yield producers in the Lower Paleozoic marine organic matter-rich rocks in the Sichuan Basin are closely related to the degree of fracture development in brittle shales.

  12. Fractured reservoir discrete feature network technologies. Final report, March 7, 1996 to September 30, 1998

    Energy Technology Data Exchange (ETDEWEB)

    Dershowitz, William S.; Einstein, Herbert H.; LaPoint, Paul R.; Eiben, Thorsten; Wadleigh, Eugene; Ivanova, Violeta

    1998-12-01

    This report summarizes research conducted for the Fractured Reservoir Discrete Feature Network Technologies Project. The five areas studied are development of hierarchical fracture models; fractured reservoir compartmentalization, block size, and tributary volume analysis; development and demonstration of fractured reservoir discrete feature data analysis tools; development of tools for data integration and reservoir simulation through application of discrete feature network technologies for tertiary oil production; quantitative evaluation of the economic value of this analysis approach.

  13. Operative Fixation of Rib Fractures Indications, Techniques, and Outcomes.

    Science.gov (United States)

    Galos, David; Taylor, Benjamin; McLaurin, Toni

    2017-01-01

    Rib fractures are extremely common injuries and vary in there severity from single nondisplaced fractures to multiple segmental fractures resulting in flail chest and respiratory compromise. Historically, rib fractures have been treated conservatively with pain control and respiratory therapy. However this method may not be the best treatment modality in all situations. Operative fixation of select rib fractures has been increasing in popularity especially in patients with flail chest and respiratory compromise. Newer techniques use muscle sparing approaches and precontoured locking plate technology to obtain stable fixation and allow improved respiration. Current reports shows that rib fracture fixation offers the benefits of improved respiratory mechanics and improved pain control in the severe chest wall injury with resultant improvement in patient outcomes by decreasing time on the ventilator, time in the intensive care unit, and overall hospital length of stay.

  14. Open tibial shaft fractures: II. Definitive management and limb salvage.

    Science.gov (United States)

    Melvin, J Stuart; Dombroski, Derek G; Torbert, Jesse T; Kovach, Stephen J; Esterhai, John L; Mehta, Samir

    2010-02-01

    Definitive treatment of open fractures of the tibial diaphysis is challenging. The high-energy nature of these fractures, as well as the contamination of the fracture site and devitalization of the soft-tissue envelope, greatly increases the risk of infection, nonunion, and wound complications. The goals of definitive treatment include wound coverage or closure; prevention of infection; restoration of length, alignment, rotation, and stability; fracture healing; and return of function. Advances in orthobiologics, modern plastic surgical techniques, and fracture stabilization methods, most notably locked intramedullary nailing, have led to improved prognosis for functional recovery and limb salvage. Despite improved union and limb salvage rates, the prognosis for severe type III open fracture of the tibial shaft remains guarded, and outcomes are often determined by patient psychosocial variables.

  15. Fracture prevention in men

    NARCIS (Netherlands)

    Geusens, PP; Sambrook, P.N.; Lems, W.F.

    2009-01-01

    The lifetime risk of experiencing a fracture in 50-year-old men is lower (20%) than the risk in women (50%). Consequently, much less research has been carried out on osteoporosis and fracture risk in men. Differences in the risk and incidence of fractures between men and women are related to differe

  16. Imaging of insufficiency fractures

    Energy Technology Data Exchange (ETDEWEB)

    Krestan, Christian [Department of Radiology, Medical University of Vienna, Vienna General Hospital, Waehringerstr. 18-20, 1090 Vienna (Austria)], E-mail: christian.krestan@meduniwien.ac.at; Hojreh, Azadeh [Department of Radiology, Medical University of Vienna, Vienna General Hospital, Waehringerstr. 18-20, 1090 Vienna (Austria)

    2009-09-15

    This review focuses on the occurrence, imaging and differential diagnosis of insufficiency fractures. Prevalence, the most common sites of insufficiency fractures and their clinical implications are discussed. Insufficiency fractures occur with normal stress exerted on weakened bone. Postmenopausal osteoporosis is the most common cause of insufficiency fractures. Other conditions which affect bone turnover include osteomalacia, hyperparathyroidism, chronic renal failure and high-dose glucocorticoid therapy. It is a challenge for the radiologist to detect and diagnose insufficiency fractures, and to differentiate them from other bone lesions. Radiographs are still the most widely used imaging method for identification of insufficiency fractures, but sensitivity is limited, depending on the location of the fractures. Magnetic resonance imaging (MRI) is a very sensitive tool to visualize bone marrow abnormalities associated with insufficiency fractures. Thin section, multi-detector computed tomography (MDCT) depicts subtle fracture lines allowing direct visualization of cortical and trabecular bone. Bone scintigraphy still plays a role in detecting fractures, with good sensitivity but limited specificity. The most important differential diagnosis is underlying malignant disease leading to pathologic fractures. Bone densitometry and clinical history may also be helpful in confirming the diagnosis of insufficiency fractures.

  17. Influence of microstructure on fracture toughness of austempered ductile iron

    Energy Technology Data Exchange (ETDEWEB)

    Rao, P.P.; Putatunda, S.K. [Wayne State Univ., Detroit, MI (United States). Dept. of Chemical Engineering and Materials Science

    1997-07-01

    An investigation was carried out to examine the influence of microstructure on the plane strain fracture toughness of austempered ductile iron. Austempered ductile iron (ADI) alloyed with nickel, copper, and molybdenum was austenitized and subsequently austempered over a range of temperatures to produce different microstructures. The microstructures were characterized through optical microscopy and X-ray diffraction. Plane strain fracture toughness of all these materials was determined and was correlated with the microstructure. The results of the present investigation indicate that the lower bainitic microstructure results in higher fracture toughness than upper bainitic microstructure. Both volume fraction of retained austenite and its carbon content influence the fracture toughness. The retained austenite content of 25 vol pct was found to provide the optimum fracture toughness. It was further concluded that the carbon content of the retained austenite should be as high as possible to improve fracture toughness.

  18. GHGfrack: An Open-Source Model for Estimating Greenhouse Gas Emissions from Combustion of Fuel during Drilling and Hydraulic Fracturing.

    Science.gov (United States)

    Vafi, Kourosh; Brandt, Adam

    2016-07-19

    This paper introduces GHGfrack, an open-source engineering-based model that estimates energy consumption and associated GHG emissions from drilling and hydraulic fracturing operations. We describe verification and calibration of GHGfrack against field data for energy and fuel consumption. We run GHGfrack using data from 6927 wells in Eagle Ford and 4431 wells in Bakken oil fields. The average estimated energy consumption in Eagle Ford wells using lateral hole diameters of 8 (3)/4 and 6 (1)/8 in. are 2.25 and 2.73 TJ/well, respectively. The average estimated energy consumption in Bakken wells using hole diameters of 6 in. for horizontal section is 2.16 TJ/well. We estimate average greenhouse gas (GHG) emissions of 419 and 510 tonne of equivalent CO2 per well (tonne of CO2 eq/well) for the two aforementioned assumed geometries in Eagle Ford, respectively, and 417 tonne of CO2 eq/well for the case of Bakken. These estimates are limited only to GHG emissions from combustion of diesel fuel to supply energy only for rotation of drill string, drilling mud circulation, and fracturing pumps. Sensitivity analysis of the model shows that the top three key variables in driving energy intensity in drilling are the lateral hole diameter, drill pipe internal diameter, and mud flow rate. In hydraulic fracturing, the top three are lateral casing diameter, fracturing fluid volume, and length of the lateral.

  19. Imaging hydraulic fractures by microseismic migration for downhole monitoring system

    Science.gov (United States)

    Lin, Ye; Zhang, Haijiang

    2016-12-01

    It has been a challenge to accurately characterize fracture zones created by hydraulic fracturing from microseismic event locations. This is because generally detected events are not complete due to the associated low signal to noise ratio and some fracturing stages may not produce microseismic events even if fractures are well developed. As a result, spatial distribution of microseismic events may not well represent fractured zones by hydraulic fracturing. Here, we propose a new way to characterize the fractured zones by reverse time migration (RTM) of microseismic waveforms from some events. This is based on the fact that fractures filled with proppants and other fluids can act as strong scatterers for seismic waves. Therefore, for multi-stage hydraulic fracturing, recorded waveforms from microseismic events induced in a more recent stage may be scattered by fractured zones from previous stages. Through RTM of microseismic waveforms in the current stage, we can determine fractured zones created in previous stages by imaging area of strong scattering. We test the feasibility of this method using synthetic models with different configurations of microseismic event locations and borehole sensor positions for a 2D downhole microseismic monitoring system. Synthetic tests show that with a few events fractured zones can be directly imaged and thus the stimulated reservoir volume (SRV) can be estimated. Compared to the conventional location-based SRV estimation method, the proposed new method does not depend on the completeness of detected events and only a limited number of detected and located events are necessary for characterizing fracture distribution. For simplicity, the 2D model is used for illustrating the concept of microseismic RTM for imaging the fracture zone but the method can be adapted to real cases in the future.

  20. Characteristics of the nuclear magnetic resonance logging response in fracture oil and gas reservoirs

    Energy Technology Data Exchange (ETDEWEB)

    Xiao Lizhi; Li Kui, E-mail: xiaolizhi@cup.edu.cn [State Key Laboratory of Petroleum Resources and Prospecting, China University of Petroleum, Beijing 102249 (China)

    2011-04-15

    Fracture oil and gas reservoirs exist in large numbers. The accurate logging evaluation of fracture reservoirs has puzzled petroleum geologists for a long time. Nuclear magnetic resonance (NMR) logging is an effective new technology for borehole measurement and formation evaluation. It has been widely applied in non-fracture reservoirs, and good results have been obtained. But its application in fracture reservoirs has rarely been reported in the literature. This paper studies systematically the impact of fracture parameters (width, number, angle, etc), the instrument parameter (antenna length) and the borehole condition (type of drilling fluid) on NMR logging by establishing the equation of the NMR logging response in fracture reservoirs. First, the relationship between the transverse relaxation time of fluid-saturated fracture and fracture aperture in the condition of different transverse surface relaxation rates was analyzed; then, the impact of the fracture aperture, dip angle, length of two kinds of antennas and mud type was calculated through forward modeling and inversion. The results show that the existence of fractures affects the NMR logging; the characteristics of the NMR logging response become more obvious with increasing fracture aperture and number of fractures. It is also found that T{sub 2} distribution from the fracture reservoir will be affected by echo spacing, type of drilling fluids and length of antennas. A long echo spacing is more sensitive to the type of drilling fluid. A short antenna is more effective for identifying fractures. In addition, the impact of fracture dip angle on NMR logging is affected by the antenna length.

  1. Dynamics and Scaling Properties of Fractures in clay-like Materials

    Energy Technology Data Exchange (ETDEWEB)

    Walmann, Thomas

    1998-12-31

    Computer models that can help oil companies predict realistic and physically correct fracture patterns are important. To verify such a model, experiments described in this thesis were undertaken, using wet clay and powder. The main focus was on extensional fractures, but other types of fractures were also studied. High resolution digital images of the fracture patterns were recorded and analyzed using statistical physics and fractal geometry. The characteristic shapes and size distributions of individual fractures and the overall fracture patterns obtained from laboratory model studies were compared to results from aerial photographs of a fracture pattern in a collapsed glacier that had undergone a similar deformation. A new scaling relation (a power-law) between the length of a fracture and the projected area is derived for fractures formed during clay model experiments. This scaling relation is found also in a field study of a fracture pattern in a glacier. The forms of the different distributions that characterizes fractures in clay experiments are discussed. Several characteristic lengths are associated with the laboratory experiments. They are related to the sample size and shape, the model material and the nature of the imposed deformation. The roughness of the fracture traces obtained from powder experiments was found to have a self-affine form. The roughness, or Hurst exponent, was found to have the value 0.73, plus or minus 0.09. A large number of interacting fractures were formed in the systems studied, and under such conditions the fluctuations about the direction perpendicular to the principle strain direction are influenced by neighbouring fractures. As expected, an upper cutoff for the scaling range was observed. But the length at which the crossover from a self-affine shape to a flat shape took place did not depend systematically on any of the experimental parameters or characteristic length scales. The total fracture trace patterns could not be

  2. Analytic crack solutions for tilt fields around hydraulic fractures

    Energy Technology Data Exchange (ETDEWEB)

    Warpinski, N.R.

    2000-01-05

    The recent development of downhole tiltmeter arrays for monitoring hydraulic fractures has provided new information on fracture growth and geometry. These downhole arrays offer the significant advantages of being close to the fracture (large signal) and being unaffected by the free surface. As with surface tiltmeter data, analysis of these measurements requires the inversion of a crack or dislocation model. To supplement the dislocation models of Davis [1983], Okada [1992] and others, this work has extended several elastic crack solutions to provide tilt calculations. The solutions include constant-pressure 2D, penny-shaped, and 3D-elliptic cracks and a 2D-variable-pressure crack. Equations are developed for an arbitrary inclined fracture in an infinite elastic space. Effects of fracture height, fracture length, fracture dip, fracture azimuth, fracture width and monitoring distance on the tilt distribution are given, as well as comparisons with the dislocation model. The results show that the tilt measurements are very sensitive to the fracture dimensions, but also that it is difficult to separate the competing effects of the various parameters.

  3. Proximal humerus fractures.

    Science.gov (United States)

    Price, Matthew C; Horn, Pamela L; Latshaw, James C

    2013-01-01

    Proximal humerus fractures are among the most common fractures associated with osteoporosis. With an aging population, incidence of these fractures will only increase. The proximal humerus not only forms the lateral portion of the shoulder articulation but also has significant associations with musculoskeletal and neurovascular structures. As a result, fractures of the proximal humerus can significantly impact not only the function of the shoulder joint, but the health and function of the entire upper extremity as well. Understanding of these fractures, the management options, and associated nursing care, can help reduce morbidity rate and improve functional outcomes.

  4. Stress fractures in runners.

    Science.gov (United States)

    McCormick, Frank; Nwachukwu, Benedict U; Provencher, Matthew T

    2012-04-01

    Stress fractures are a relatively common entity in athletes, in particular, runners. Physicians and health care providers should maintain a high index of suspicion for stress fractures in runners presenting with insidious onset of focal bone tenderness associated with recent changes in training intensity or regimen. It is particularly important to recognize “high-risk” fractures, as these are associated with an increased risk of complication. A patient with confirmed radiographic evidence of a high-risk stress fracture should be evaluated by an orthopedic surgeon. Runners may benefit from orthotics, cushioned sneakers, interval training, and vitamin/calcium supplementation as a means of stress fracture prevention.

  5. Role of MRI in hip fractures, including stress fractures, occult fractures, avulsion fractures

    Energy Technology Data Exchange (ETDEWEB)

    Nachtrab, O. [Department of Radiology, The Robert Jones and Agnes Hunt Orthopaedic Hospital, Gobowen, Oswestry Shropshire SY10 7AG (United Kingdom); Cassar-Pullicino, V.N., E-mail: Victor.Pullicino@rjah.nhs.uk [Department of Radiology, The Robert Jones and Agnes Hunt Orthopaedic Hospital, Gobowen, Oswestry Shropshire SY10 7AG (United Kingdom); Lalam, R.; Tins, B.; Tyrrell, P.N.M.; Singh, J. [Department of Radiology, The Robert Jones and Agnes Hunt Orthopaedic Hospital, Gobowen, Oswestry Shropshire SY10 7AG (United Kingdom)

    2012-12-15

    MR imaging plays a vital role in the diagnosis and management of hip fractures in all age groups, in a large spectrum of patient groups spanning the elderly and sporting population. It allows a confident exclusion of fracture, differentiation of bony from soft tissue injury and an early confident detection of fractures. There is a spectrum of MR findings which in part is dictated by the type and cause of the fracture which the radiologist needs to be familiar with. Judicious but prompt utilisation of MR in patients with suspected hip fractures has a positive therapeutic impact with healthcare cost benefits as well as social care benefits.

  6. Fractures in multiple sclerosis

    DEFF Research Database (Denmark)

    Stenager, E; Jensen, K

    1991-01-01

    In a cross-sectional study of 299 MS patients 22 have had fractures and of these 17 after onset of MS. The fractures most frequently involved the femoral neck and trochanter (41%). Three patients had had more than one fracture. Only 1 patient had osteoporosis. The percentage of fractures increased...... with increasing age and disease duration. Among 34 deceased MS patients 4 had had fractures. These findings are discussed in relation to physical and cognitive impairment in MS. A case-control study is recommended....

  7. RAP-011 augments callus formation in closed fractures in rats.

    Science.gov (United States)

    Morse, Alyson; Cheng, Tegan L; Peacock, Lauren; Mikulec, Kathy; Little, David G; Schindeler, Aaron

    2016-02-01

    ACE-011 is a bone anabolic agent generated by fusing the extracellular domain of the Activin Type 2A receptor (ActRIIA) to an IgG-Fc. The orthopedic utility of ACE-011 was investigated using a murine analogue, RAP-011. Initially, a rat closed fracture model was tested using bi-weekly (biw) 10 mg/kg RAP-011. RAP-011 significantly increased callus length and callus bone volume (BV, +43% at 6w, p RAP-011(p)] and "sustained" [RAP-011(s)] regimens of biw 0.6mg/kg × 2, 0.35mg/kg × 3 and 0.18mg/kg × 2, 0.1mg/kg × 7 respectively, compared with PTH(1-34) (25 μg/kg/d) and vehicle controls. RAP-011 treatments gave modest increases in callus length and callus BV at 6w (p RAP-011 is effective in promoting bone formation during repair, but optimizing callus bone quality will require further investigation. © 2015 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.

  8. Research and practice of the impulse sand fracturing technology

    Directory of Open Access Journals (Sweden)

    Bin Qian

    2015-10-01

    Full Text Available With the deep development of tight sand gas reservoirs, problems such as short stable production period and quick production decline of gas wells after fracturing have become increasingly prominent. Consequently, there is an increasing demand for the effective penetration and conductivity of artificial fractures. Impulse sand fracturing technology introduces a concept of discrete multilayer sanding inside fractures; joint application of pulse blender which can be switched at high frequency, intensive multi-cluster perforation and special fibrous material made it possible to ensure the flow stability of proppant slug, and placement of nonuniformly-laid sand pinnacles and grooves, which markedly upgraded the capacity of the fracture conductivity to several orders of magnitude more than the conventional method. Laboratory engineering simulation evaluation and field test show that pre-fracturing reservoir evaluation, pulse time design and the optimization of degradable fiber and support equipment are the keys to the success of impulse sand fracturing. Compared with the conventional fracturing, this technique can effectively increase well production, decrease the volume of fracturing proppant, and lower sand plugging risks. An independent sand fracturing pilot test has been conducted in 6 layers of 3 wells for the first time in Block Tao 7 of the Sulige Gasfield, Ordos Basin, as a result, the average volume of fracturing proppant dropped by 28.3%, the average sand intensity dropped by 21.88%, and the post-fracturing average daily gas output increased by 26.8%. This technology provides an efficient and environmentally friendly reservoir stimulation option for tight sand gas reservoirs in China.

  9. Sex-specific mediation effect of the right fusiform face area volume on the association between variants in repeat length of AVPR1A RS3 and altruistic behavior in healthy adults.

    Science.gov (United States)

    Wang, Junping; Qin, Wen; Liu, Feng; Liu, Bing; Zhou, Yuan; Jiang, Tianzi; Yu, Chunshui

    2016-07-01

    Microsatellite variants in the arginine vasopressin receptor 1A gene (AVPR1A) RS3 have been associated with normal social behaviors variation and autism spectrum disorders (ASDs) in a sex-specific manner. However, neural mechanisms underlying these associations remain largely unknown. We hypothesized that AVPR1A RS3 variants affect altruistic behavior by modulating the gray matter volume (GMV) of specific brain regions in a sex-specific manner. We investigated 278 young healthy adults using the Dictator Game to assess altruistic behavior. All subjects were genotyped and main effect of AVPR1A RS3 repeat polymorphisms and interaction of genotype-by-sex on the GMV were assessed in a voxel-wise manner. We observed that male subjects with relatively short repeats allocated less money to others and exhibited a significantly smaller GMV in the right fusiform face area (FFA) compared with male long homozygotes. In male subjects, the GMV of the right FFA exhibited a significant positive correlation with altruistic behavior. A mixed mediation and moderation analysis further revealed both a significant mediation effect of the GMV of the right FFA on the association between AVPR1A RS3 repeat polymorphisms and allocation sums and a significant moderation effect of sex (only in males) on the mediation effect. Post hoc analysis showed that the GMV of the right FFA was significantly smaller in male subjects carrying allele 426 than in non-426 carriers. These results suggest that the GMV of the right FFA may be a potential mediator whereby the genetic variants in AVPR1A RS3 affect altruistic behavior in healthy male subjects. Hum Brain Mapp 37:2700-2709, 2016. © 2016 Wiley Periodicals, Inc.

  10. [Fractures of carpal bones].

    Science.gov (United States)

    Lögters, T; Windolf, J

    2016-10-01

    Fractures of the carpal bones are uncommon. On standard radiographs fractures are often not recognized and a computed tomography (CT) scan is the diagnostic method of choice. The aim of treatment is to restore pain-free and full functioning of the hand. A distinction is made between stable and unstable carpal fractures. Stable non-displaced fractures can be treated conservatively. Unstable and displaced fractures have an increased risk of arthritis and non-union and should be stabilized by screws or k‑wires. If treated adequately, fractures of the carpal bones have a good prognosis. Unstable and dislocated fractures have an increased risk for non-union. The subsequent development of carpal collapse with arthrosis is a severe consequence of non-union, which has a heterogeneous prognosis.

  11. Orbital fractures: a review

    Directory of Open Access Journals (Sweden)

    Jeffrey M Joseph

    2011-01-01

    Full Text Available Jeffrey M Joseph, Ioannis P GlavasDivision of Ophthalmic Plastic and Reconstructive Surgery, Department of Ophthalmology, School of Medicine, New York University, New York, NY, USA; Manhattan Eye, Ear, and Throat Hospital, New York, NY, USAAbstract: This review of orbital fractures has three goals: 1 to understand the clinically relevant orbital anatomy with regard to periorbital trauma and orbital fractures, 2 to explain how to assess and examine a patient after periorbital trauma, and 3 to understand the medical and surgical management of orbital fractures. The article aims to summarize the evaluation and management of commonly encountered orbital fractures from the ophthalmologic perspective and to provide an overview for all practicing ophthalmologists and ophthalmologists in training.Keywords: orbit, trauma, fracture, orbital floor, medial wall, zygomatic, zygomatic complex, zmc fracture, zygomaticomaxillary complex fractures 

  12. Oblique Axis Body Fracture

    DEFF Research Database (Denmark)

    Takai, Hirokazu; Konstantinidis, Lukas; Schmal, Hagen

    2016-01-01

    Purpose. Anderson type III odontoid fractures have traditionally been considered stable and treated conservatively. However, unstable cases with unfavorable results following conservative treatment have been reported. Methods. We present the cases of two patients who sustained minimally displaced...... Anderson type III fractures with a characteristic fracture pattern that we refer to as "oblique type axis body fracture." Results. The female patients aged 90 and 72 years, respectively, were both diagnosed with minimally displaced Anderson type III fractures. Both fractures had a characteristic "oblique...... type" fracture pattern. The first patient was treated conservatively with cervical spine immobilization in a semirigid collar. However, gross displacement was noted at the 6-week follow-up visit. The second patient was therefore treated operatively by C1-C3/4 posterior fusion and the course...

  13. Crack branching in carbon steel. Fracture mechanisms

    Science.gov (United States)

    Syromyatnikova, A. S.; Alekseev, A. A.; Levin, A. I.; Lyglaev, A. V.

    2010-04-01

    The fracture surfaces of pressure vessels made of carbon steel that form during crack branching propagation are examined by fractography. Crack branching is found to occur at a crack velocity higher than a certain critical value V > V c . In this case, the material volume that is involved in fracture and depends on the elastoplastic properties of the material and the sample width has no time to dissipate the energy released upon crack motion via the damage mechanisms intrinsic in the material under given deformation conditions (in our case, via cracking according to intragranular cleavage).

  14. Fracture Toughness Prediction for MWCNT Reinforced Ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Henager, Charles H.; Nguyen, Ba Nghiep

    2013-09-01

    This report describes the development of a micromechanics model to predict fracture toughness of multiwall carbon nanotube (MWCNT) reinforced ceramic composites to guide future experimental work for this project. The modeling work described in this report includes (i) prediction of elastic properties, (ii) development of a mechanistic damage model accounting for matrix cracking to predict the composite nonlinear stress/strain response to tensile loading to failure, and (iii) application of this damage model in a modified boundary layer (MBL) analysis using ABAQUS to predict fracture toughness and crack resistance behavior (R-curves) for ceramic materials containing MWCNTs at various volume fractions.

  15. Discrete Fracture Networks Groundwater Modelling at Bedding Control Fractured Sedimentary Rock mass

    Science.gov (United States)

    Pin, Yeh; Yuan-Chieh, Wu

    2017-04-01

    Groundwater flow modelling in fractured rock mass is an important challenging work in predicting the transport of contamination. So far as we know about the numerical analysis method was consider for crystalline rock, which means discontinuous are treated as stochastic distribution in homogeneous rock mass. Based on the understanding of geology in Taiwan in past few decades, we know that the hydraulic conductivities of Quaternary and Tertiary system rock mass are strongly controlled by development of sedimentary structures (bedding plane). The main purpose of this study is to understand how Discrete Fracture Networks (DFN) affects numerical results in terms of hydraulic behavior using different DFN generation methods. Base on surface geology investigation and core drilling work (3 boreholes with a total length of 120m), small scale fracture properties with in Cho-lan formation (muddy sandstone) are defined, including gently dip of bedding and 2 sub-vertical joint sets. Two FracMan/MAFIC numerical modellings are conducted, using ECPM approach (Equivalent Continuum Porous Media); case A considered all fracture were Power law distribution with Poisson fracture center; case B considered all bedding plans penetrate into modelling region, and remove the bedding count to recalculate joint fracture parameters. Modelling results show that Case B gives stronger groundwater pathways than Case A and have impact on flow field. This preliminary modelling result implicates the groundwater flow modelling work in some fractured sedimentary rock mass, might be considerate to rock sedimentary structure development itself, discontinuous maybe not follow the same stochastic DFN parameter.

  16. Application of Discrete Fracture Modeling and Upscaling Techniques to Complex Fractured Reservoirs

    Science.gov (United States)

    Karimi-Fard, M.; Lapene, A.; Pauget, L.

    2012-12-01

    During the last decade, an important effort has been made to improve data acquisition (seismic and borehole imaging) and workflow for reservoir characterization which has greatly benefited the description of fractured reservoirs. However, the geological models resulting from the interpretations need to be validated or calibrated against dynamic data. Flow modeling in fractured reservoirs remains a challenge due to the difficulty of representing mass transfers at different heterogeneity scales. The majority of the existing approaches are based on dual continuum representation where the fracture network and the matrix are represented separately and their interactions are modeled using transfer functions. These models are usually based on idealized representation of the fracture distribution which makes the integration of real data difficult. In recent years, due to increases in computer power, discrete fracture modeling techniques (DFM) are becoming popular. In these techniques the fractures are represented explicitly allowing the direct use of data. In this work we consider the DFM technique developed by Karimi-Fard et al. [1] which is based on an unstructured finite-volume discretization. The mass flux between two adjacent control-volumes is evaluated using an optimized two-point flux approximation. The result of the discretization is a list of control-volumes with the associated pore-volumes and positions, and a list of connections with the associated transmissibilities. Fracture intersections are simplified using a connectivity transformation which contributes considerably to the efficiency of the methodology. In addition, the method is designed for general purpose simulators and any connectivity based simulator can be used for flow simulations. The DFM technique is either used standalone or as part of an upscaling technique. The upscaling techniques are required for large reservoirs where the explicit representation of all fractures and faults is not possible

  17. Mappability and Read Length

    Directory of Open Access Journals (Sweden)

    Wentian eLi

    2014-11-01

    Full Text Available Power-law distributions are the main functional form forthe distribution of repeat size and repeat copy number in the human genome. When the genome is broken into fragments for sequencing, the limited size offragments and reads may prevent an unique alignment of repeatsequences to the reference sequence. Repeats in the human genome canbe as long as $10^4$ bases, or $10^5-10^6$ bases when allowing for mismatches between repeat units. Sequence reads from these regions are therefore unmappable when the read length is in the range of $10^3$ bases.With the read length of exactly 1000 bases, slightly more than 1% of theassembled genome, and slightly less than 1% of the 1kbreads, are unmappable, excluding the unassembled portion of the humangenome (8% in GRCh37. The slow decay (long tail ofthe power-law function implies a diminishing return in convertingunmappable regions/reads to become mappable with the increase of theread length, with the understanding that increasing read length willalways move towards the direction of 100% mappability.

  18. Telomere Length and Mortality

    DEFF Research Database (Denmark)

    Kimura, Masayuki; Hjelmborg, Jacob V B; Gardner, Jeffrey P

    2008-01-01

    telomeres predicted the death of the first co-twin better than the mTRFL did (mTRFL: 0.56, 95% confidence interval (CI): 0.49, 0.63; mTRFL(50): 0.59, 95% CI: 0.52, 0.66; mTRFL(25): 0.59, 95% CI: 0.52, 0.66; MTRFL: 0.60, 95% CI: 0.53, 0.67). The telomere-mortality association was stronger in years 3-4 than......Leukocyte telomere length, representing the mean length of all telomeres in leukocytes, is ostensibly a bioindicator of human aging. The authors hypothesized that shorter telomeres might forecast imminent mortality in elderly people better than leukocyte telomere length. They performed mortality...... analysis in 548 same-sex Danish twins (274 pairs) aged 73-94 years, of whom 204 pairs experienced the death of one or both co-twins during 9-10 years of follow-up (1997-2007). From the terminal restriction fragment length (TRFL) distribution, the authors obtained the mean TRFL (mTRFL) and the mean values...

  19. [Fracture endoprosthesis of distal humerus fractures].

    Science.gov (United States)

    Müller, L P; Wegmann, K; Burkhart, K J

    2013-08-01

    The treatment of choice for fractures of the distal humerus is double plate osteosynthesis. Due to anatomical preshaped angle stable plates the primary stability and management of soft tissues has been improved. However, osteoporotic comminuted fractures in the elderly are often not amenable to stable osteosynthesis and total elbow arthroplasty has been established as an alternative therapy. Although complication rates have been reduced, complications of total elbow arthroplasty are still much more frequent than in total hip replacement. Furthermore, patients are advised not to exceed a weight bearing of 5 kg. Therefore, the indications for elbow arthroplasty must be evaluated very strictly and should be reserved for comminuted distal humeral fractures in the elderly with poor bone quality that are not amenable to stable osteosynthesis or for simple fractures in cases of preexisting symptomatic osteoarthritis. This article introduces and discusses modern concepts of elbow arthroplasty, such as modular convertible prosthesis systems, hemiarthroplasty and radial head replacement in total elbow arthroplasty.

  20. Under-reporting of osteoporotic vertebral fractures on computed tomography

    Energy Technology Data Exchange (ETDEWEB)

    Williams, Alexandra L. [Department of Radiology, Manchester Royal Infirmary, Oxford Road, Manchester (United Kingdom)], E-mail: alexandra.firth@virgin.net; Al-Busaidi, Aisha [Department of Radiology, Manchester Royal Infirmary, Oxford Road, Manchester (United Kingdom)], E-mail: albusaidi@doctors.org.uk; Sparrow, Patrick J. [Department of Radiology, Manchester Royal Infirmary, Oxford Road, Manchester (United Kingdom)], E-mail: patsparrow@doctors.org.uk; Adams, Judith E. [Department of Radiology, Manchester Royal Infirmary, Oxford Road, Manchester (United Kingdom); Department of Clinical Radiology, Imaging Science and Biomedical Engineering, Stopford Building, , University of Manchester, Oxford Road, Manchester M13 9PT (United Kingdom)], E-mail: judith.adams@manchester.ac.uk; Whitehouse, Richard W. [Department of Radiology, Manchester Royal Infirmary, Oxford Road, Manchester (United Kingdom)], E-mail: Richard.Whitehouse@cmmc.nhs.uk

    2009-01-15

    Purpose: Osteoporotic vertebral fractures are frequently asymptomatic. They are often not diagnosed clinically or radiologically. Despite this, prevalent osteoporotic vertebral fractures predict future osteoporotic fractures and are associated with increased mortality and morbidity. Appropriate management of osteoporosis can reduce future fracture risk. Fractures on lateral chest radiographs taken for other conditions are frequently overlooked by radiologists. Our aim was to assess the value of computed tomography (CT) in the diagnosis of vertebral fracture and identify the frequency with which significant fractures are missed. Materials and methods: The thoracic CT scans of 100 consecutive male and 100 consecutive female patients over 55 years were reviewed. CT images were acquired on General Electric Lightspeed multi-detector (MD) CT scanners (16 or 32 row) using 1.25 mm slice thickness. Midline sagittal images were reconstructed from the 3D volume images. The presence of moderate (25-40% height loss) or severe (>40% height loss) vertebral fractures between T1 and L1 was determined using an established semi-quantitative method and confirmed by morphological measurement. Results were compared with the formal CT report. Results: Scans of 192 patients were analysed (95 female; 97 male); mean age 70.1 years. Thirty-eight (19.8%) patients had one or more moderate to severe vertebral fractures. Only 5 (13%) were correctly reported as having osteoporotic fractures in the official report. The sensitivity of axial CT images to vertebral fracture was 0.35. Conclusion: Incidental osteoporotic vertebral fractures are under-reported on CT. The sensitivity of axial images in detecting these fractures is poor. Sagittal reformations are strongly recommended to improve the detection rate.

  1. Concomitant upper limb fractures and short-term functional recovery in hip fracture patients: does the site of upper limb injury matter?

    Science.gov (United States)

    Di Monaco, Marco; Castiglioni, Carlotta; Vallero, Fulvia; Di Monaco, Roberto; Tappero, Rosa

    2015-05-01

    The aim of this study was to evaluate functional recovery in a subgroup of hip fracture patients who sustained a simultaneous fracture at the upper limb, taking into account the site of upper limb injury. Of 760 patients admitted consecutively to the authors' rehabilitation hospital because of a fall-related hip fracture, 700 were retrospectively investigated. Functional outcome was assessed using Barthel Index scores. In 49 of the 700 patients, a single fall resulted in both a hip fracture and a fracture of either wrist (n = 34) or proximal humerus (n = 15). The patients with concomitant shoulder fractures had lower median Barthel Index scores after rehabilitation (70 vs. 90, P = 0.003), lower median Barthel Index effectiveness (57.1 vs. 76.9, P = 0.018), and prolonged median length of stay (42 vs. 36 days, P = 0.011) than did the patients with isolated hip fractures. Significant differences persisted after adjustment for six potential confounders. The adjusted odds ratio for achieving a Barthel Index score lower than 85 was 6.71 (95% confidence interval, 1.68-26.81; P = 0.007) for the patients with concomitant shoulder fractures. Conversely, no prognostic disadvantages were associated with concomitant wrist fractures. Data show a worse functional recovery and a prolonged length of stay in the subgroup of hip fracture patients who sustained a concomitant fracture at the proximal humerus, but not at the wrist.

  2. Jaw fractures in children.

    Science.gov (United States)

    Kotilainen, R; Kärjä, J; Kullaa-Mikkonen, A

    1990-03-01

    From a total of 350 jaw fractures treated in 1980-1984 at Kuopio University Central Hospital, 20% were in children. These injuries were evaluated retrospectively regarding age, sex, incidence and etiology. Forty-five of the patients were boys and 25 girls. The frequency of maxillary and mandibular fractures in 70 young patients was 28.6%. The most common type of bone fractures was fracture of the alveolar process, which was prevalent in persons with mixed dentition. Before the age of 7 years, falls from height were the common causes of jaw fractures. The major cause of the jaw fractures in children from 7 to 15 years old was road accidents (47.1%), especially in boys. Most of these were cycling accidents, only a few patients were victims of automobile accidents. In addition, about one third (25.7%) of the patients were treated in the hospital because of multiple injuries to other organs.

  3. Growing skull fracture

    Directory of Open Access Journals (Sweden)

    Mihajlović Miljan H.

    2006-01-01

    Full Text Available Background. Growing skull fracture or craniocerebral erosion is a rare complication of linear skull fracture in childhood. It is characterized by progressive diastatic enlargement of the fracture line, which leads to a cranial defect, dural cleft, and cerebral herniation. It is presented as a soft pulsabile scalp swelling above the fracture, with a clear cranial defect. Case report. In this paper we presented a patient, an 8-month-old boy with the growing skull fracture revealed four weeks after the injury. After the surgical treatment, the boy was in a good general condition without the presence of neurologic impairment. Conclusion. Early recognition of craniocerebral erosion is very important. Timely detection prevents further progression of the disease and the evolution of neurological impairment. Surgery is the method of choice for treating a growing skull fracture .

  4. Compilation of fatigue, fatigue-crack propagation, and fracture data for 2024 and 7075 aluminum, Ti-6Al-4V titanium, and 300M steel. Volume 1: Description of data and data storage on magnetic tape. Volume 2: Data tape (7-track magnetic tape)

    Science.gov (United States)

    Rice, R. C.; Reynolds, J. L.

    1976-01-01

    Fatigue, fatigue-crack-propagation, and fracture data compiled and stored on magnetic tape are documented. Data for 202 and 7075 aluminum alloys, Ti-6Al-4V titanium alloy, and 300M steel are included in the compilation. Approximately 4,500 fatigue, 6,500 fatigue-crack-propagation, and 1,500 fracture data points are stored on magnetic tape. Descriptions of the data, an index to the data on the magnetic tape, information on data storage format on the tape, a listing of all data source references, and abstracts of other pertinent test information from each data source reference are included.

  5. Relativistic length agony continued

    Directory of Open Access Journals (Sweden)

    Redžić D.V.

    2014-01-01

    Full Text Available We made an attempt to remedy recent confusing treatments of some basic relativistic concepts and results. Following the argument presented in an earlier paper (Redžić 2008b, we discussed the misconceptions that are recurrent points in the literature devoted to teaching relativity such as: there is no change in the object in Special Relativity, illusory character of relativistic length contraction, stresses and strains induced by Lorentz contraction, and related issues. We gave several examples of the traps of everyday language that lurk in Special Relativity. To remove a possible conceptual and terminological muddle, we made a distinction between the relativistic length reduction and relativistic FitzGerald-Lorentz contraction, corresponding to a passive and an active aspect of length contraction, respectively; we pointed out that both aspects have fundamental dynamical contents. As an illustration of our considerations, we discussed briefly the Dewan-Beran-Bell spaceship paradox and the ‘pole in a barn’ paradox. [Projekat Ministarstva nauke Republike Srbije, br. 171028

  6. Ground Wood Fiber Length Distributions

    OpenAIRE

    Lauri Ilmari Salminen; Sari Liukkonen; Alava, Mikko J.

    2014-01-01

    This study considers ground wood fiber length distributions arising from pilot grindings. The empirical fiber length distributions appear to be independent of wood fiber length as well as feeding velocity. In terms of mathematics the fiber fragment distributions of ground wood pulp combine an exponential distribution for high-length fragments and a power-law distribution for smaller lengths. This implies that the fiber length distribution is influenced by the stone surface. A fragmentation-ba...

  7. Pelvic fractures and mortality.

    OpenAIRE

    K.H. Chong; DeCoster, T.; Osler, T.; Robinson, B.

    1997-01-01

    A retrospective study of all patients (N = 343) with pelvic fractures admitted to our trauma service was conducted to evaluate the impact of pelvic fractures on mortality. All patients sustained additional injuries with an average Injury Severity Score (ISS) of twenty. Thirty-six patients died. This group had more severe pelvic fractures as graded by the Tile classification as well as a greater number and severity of associated injuries. Six patients died as a direct result of pelvic hemorrha...

  8. Oblique Axis Body Fracture

    DEFF Research Database (Denmark)

    Takai, Hirokazu; Konstantinidis, Lukas; Schmal, Hagen;

    2016-01-01

    was uneventful. Conclusions. Oblique type axis body fractures resemble a highly unstable subtype of Anderson type III fractures with the potential of severe secondary deformity following conservative treatment, irrespective of initial grade of displacement. The authors therefore warrant a high index of suspicion......Purpose. Anderson type III odontoid fractures have traditionally been considered stable and treated conservatively. However, unstable cases with unfavorable results following conservative treatment have been reported. Methods. We present the cases of two patients who sustained minimally displaced...

  9. The effects of geometry and length scale on nanomechanical properties in constrained systems

    Science.gov (United States)

    Jungk, John Michael

    2005-07-01

    The determination of mechanical properties in nanoscale geometries is becoming increasingly important as microsystem and integrated circuit technologies continue to mature. Many devices produced by these technologies are composed of materials with critical sample dimensions smaller than 100 nm. In microelectronics, this can be the thickness of a metallization or dielectric layer, while wear coatings on MEMS devices are frequently thinner than this length scale. Since structures of this type are susceptible to plasticity and fracture as a result of either contact or residual stresses, it is critical that the mechanical behavior of the individual components be well described. This thesis is directed at the development of methods for characterizing the mechanical properties in small volume systems. Using instrumented indentation techniques, typically called nanoindentation, a systematic study of the mechanical response of materials ranging from ductile metals to brittle ceramics was executed. More specifically, investigations into how single length scale approaches may be used to describe mechanical properties such as indentation hardening, ductile film delamination and strain energy release rates were performed. In addition, the acoustic energy released during the fracture of brittle ceramics was related to both stress intensity and a strain energy release rate. Finite element simulations of nanoindentation tests were performed using ABAQUS, a commercially available material modeling software program. These simulations were used to separate individual film and substrate responses from the experimentally observed film/substrate composite mechanical behavior. Finally, quasi-tribological experiments were performed to probe for transitions in friction or wear response as the local deformation varied from the nanoscale to the macroscale.

  10. Effectiveness and complications of pelvic circumferential compression devices in patients with unstable pelvic fractures: a systematic review of literature.

    NARCIS (Netherlands)

    Spanjersberg, W.R.; Knops, S.P.; Schep, N.W.; Lieshout, E.M. van; Patka, P.; Schipper, I.B.

    2009-01-01

    BACKGROUND: Pelvic fractures can cause massive haemorrhage. Early stabilisation and compression of unstable fractures is thought to limit blood loss. Reposition of fracture parts and reduction of pelvic volume may provide haemorrhage control. Several non-invasive techniques for early stabilisation h

  11. Effectiveness and complications of pelvic circumferential compression devices in patients with unstable pelvic fractures: a systematic review of literature.

    NARCIS (Netherlands)

    Spanjersberg, W.R.; Knops, S.P.; Schep, N.W.; Lieshout, E.M. van; Patka, P.; Schipper, I.B.

    2009-01-01

    BACKGROUND: Pelvic fractures can cause massive haemorrhage. Early stabilisation and compression of unstable fractures is thought to limit blood loss. Reposition of fracture parts and reduction of pelvic volume may provide haemorrhage control. Several non-invasive techniques for early stabilisation h

  12. Effectiveness and complications of pelvic circumferential compression devices in patients with unstable pelvic fractures: A systematic review of literature

    NARCIS (Netherlands)

    W.R. Spanjersberg (Willem); S.P. Knops (Simon); N.W.L. Schep (Niels); E.M.M. van Lieshout (Esther); P. Patka (Peter); I.B. Schipper (Inger)

    2009-01-01

    textabstractBackground: Pelvic fractures can cause massive haemorrhage. Early stabilisation and compression of unstable fractures is thought to limit blood loss. Reposition of fracture parts and reduction of pelvic volume may provide haemorrhage control. Several non-invasive techniques for early sta

  13. Effectiveness and complications of pelvic circumferential compression devices in patients with unstable pelvic fractures: A systematic review of literature

    NARCIS (Netherlands)

    W.R. Spanjersberg (Willem); S.P. Knops (Simon); N.W.L. Schep (Niels); E.M.M. van Lieshout (Esther); P. Patka (Peter); I.B. Schipper (Inger)

    2009-01-01

    textabstractBackground: Pelvic fractures can cause massive haemorrhage. Early stabilisation and compression of unstable fractures is thought to limit blood loss. Reposition of fracture parts and reduction of pelvic volume may provide haemorrhage control. Several non-invasive techniques for early

  14. Effectiveness and complications of pelvic circumferential compression devices in patients with unstable pelvic fractures: a systematic review of literature.

    NARCIS (Netherlands)

    Spanjersberg, W.R.; Knops, S.P.; Schep, N.W.; Lieshout, E.M. van; Patka, P.; Schipper, I.B.

    2009-01-01

    BACKGROUND: Pelvic fractures can cause massive haemorrhage. Early stabilisation and compression of unstable fractures is thought to limit blood loss. Reposition of fracture parts and reduction of pelvic volume may provide haemorrhage control. Several non-invasive techniques for early stabilisation

  15. Influence of pore pressure to the development of a hydraulic fracture in poroelastic medium

    CERN Document Server

    Golovin, Sergey V

    2016-01-01

    In this paper we demonstrate the influence of the pore pressure to the development of a hydraulically-driven fracture in a poroelastic medium. We present a novel numerical model for propagation of a planar hydraulic fracture and prove its correctness by demonstration of the numerical convergence and by comparison with known solutions. The advantage of the algorithm is that it does not require the distinguishing of the fracture's tips and reconstruction of the numerical mesh according to the fracture propagation. Next, we perform a thorough analysis of the interplay of fluid filtration and redistribution of stresses near the fracture. We demonstrate that the fracture length decreases with the increase of the Biot's number (the parameter that determines the contribution of the pore pressure to the stress) and explain this effect by analysing the near-fracture pore pressure, rock deformation and stresses. We conclude, that the correct account for the fluid exchange between the fracture and the rock should be bas...

  16. An integrated profile of natural fractures in gas-bearing shale complex (Pomerania, Poland): based on structural profiling of oriented core and borehole logging data.

    Science.gov (United States)

    Bobek, Kinga; Jarosiński, Marek; Stadtmuller, Marek; Pachytel, Radomir; Lis-Śledziona, Anita

    2016-04-01

    system, which is locally disturbed by small-scale faults and fractures, associated with them. For regular joints, observed on borehole core, we have calculated variation of mean height and area and volume of mineralization for veins. Fracture density variation reveals good correlation with lithological shale formations which are comparable with Consistent Mechanical Units differentiated based on detailed lithological profiling and geophysical data (see Pachytel et al., this issue).We have also proposed a new method of a rose diagram construction presenting strike of fractures taking into account their size and angular error bar in strike determination. Each fracture was weighted with its length or aperture and an angular error was included by blurring the less credible records. This allowed for more precise adjustment of fracture sets direction in comparison to conventional diagrams without weighting procedure. Recently, we are processing acoustic dipole logs for anisotropy analyses aiming in comparison with density of fracture sets. Our study, which is conducted in the frame of ShaleMech Project (within Blue Gas Program) is in progress, thus the presented results should be considered as preliminary.

  17. Efficient and robust compositional two-phase reservoir simulation in fractured media

    Science.gov (United States)

    Zidane, A.; Firoozabadi, A.

    2015-12-01

    Compositional and compressible two-phase flow in fractured media has wide applications including CO2 injection. Accurate simulations are currently based on the discrete fracture approach using the cross-flow equilibrium model. In this approach the fractures and a small part of the matrix blocks are combined to form a grid cell. The major drawback is low computational efficiency. In this work we use the discrete-fracture approach to model the fractures where the fracture entities are described explicitly in the computational domain. We use the concept of cross-flow equilibrium in the fractures (FCFE). This allows using large matrix elements in the neighborhood of the fractures. We solve the fracture transport equations implicitly to overcome the Courant-Freidricks-Levy (CFL) condition in the small fracture elements. Our implicit approach is based on calculation of the derivative of the molar concentration of component i in phase (cαi ) with respect to the total molar concentration (ci ) at constant volume V and temperature T. This contributes to significant speed up of the code. The hybrid mixed finite element method (MFE) is used to solve for the velocity in both the matrix and the fractures coupled with the discontinuous Galerkin (DG) method to solve the species transport equations in the matrix, and a finite volume (FV) discretization in the fractures. In large scale problems the proposed approach is orders of magnitude faster than the existing models.

  18. Fracture mechanics safety approaches

    Energy Technology Data Exchange (ETDEWEB)

    Roos, E.; Schuler, X.; Eisele, U. [Materials Testing Inst. (MPA), Univ. of Stuttgart (Germany)

    2004-07-01

    Component integrity assessments require the knowledge of reliable fracture toughness parameters characterising the initiation of the failure process in the whole relevant temperature range. From a large number of fracture mechanics tests a statistically based procedure was derived allowing to quantify the initiation of fracture toughness as a function of temperature as a closed function as well as the temperature dependence of the cleavage instability parameters. Alternatively to the direct experimental determination one also can use a correlation between fracture toughness and notch impact energy. (orig.)

  19. Scaphoid fractures in children

    Directory of Open Access Journals (Sweden)

    Gajdobranski Đorđe

    2014-01-01

    Full Text Available Introduction. Scaphoid fractures are rare in childhood. Diagnosis is very difficult to establish because carpal bones are not fully ossified. In suspected cases comparative or delayed radiography is used, as well as computerized tomography, magnetic resonance imaging, ultrasound and bone scintigraphy. Majority of scaphoid fractures are treated conservatively with good results. In case of delayed fracture healing various types of treatment are available. Objective. To determine the mechanism of injury, clinical healing process, types and outcome of treatment of scaphoid fractures in children. Methods. We retrospectively analyzed patients with traumatic closed fracture of the scaphoid bone over a ten-year period (2002-2011. The outcome of the treatment of “acute” scaphoid fracture was evaluated using the Mayo Wrist Score. Results. There were in total 34 patients, of mean age 13.8 years, with traumatic closed fracture of the scaphoid bone, whose bone growth was not finished yet. Most common injury mechanism was fall on outstretched arm - 76% of patients. During the examined period 31 children with “acute” fracture underwent conservative treatment, with average immobilization period of 51 days. Six patients were lost to follow-up. In the remaining 25 patients, after completed rehabilitation, functional results determined by the Mayo Wrist Score were excellent. Conclusion. Conservative therapy of “acute” scaphoid fractures is an acceptable treatment option for pediatric patients with excellent functional results.

  20. Atraumatic First Rib Fracture

    Directory of Open Access Journals (Sweden)

    Koray Aydogdu

    2014-12-01

    Full Text Available Rib fractures are usually seen after a trauma, while atraumatic spontaneous rib fractures are quite rare. A first rib fracture identified in our 17 years old female patient who had not a history of trauma except lifting a heavy weight was examined in details in terms of the potential complications and followed-up for a long time. We presented our experience on this case with atraumatic first rib fracture that has different views for the etiology in light of the literature.

  1. The Derivation of Fault Volumetric Properties from 3D Trace Maps Using Outcrop Constrained Discrete Fracture Network Models

    Science.gov (United States)

    Hodgetts, David; Seers, Thomas

    2015-04-01

    Fault systems are important structural elements within many petroleum reservoirs, acting as potential conduits, baffles or barriers to hydrocarbon migration. Large, seismic-scale faults often serve as reservoir bounding seals, forming structural traps which have proved to be prolific plays in many petroleum provinces. Though inconspicuous within most seismic datasets, smaller subsidiary faults, commonly within the damage zones of parent structures, may also play an important role. These smaller faults typically form narrow, tabular low permeability zones which serve to compartmentalize the reservoir, negatively impacting upon hydrocarbon recovery. Though considerable improvements have been made in the visualization field to reservoir-scale fault systems with the advent of 3D seismic surveys, the occlusion of smaller scale faults in such datasets is a source of significant uncertainty during prospect evaluation. The limited capacity of conventional subsurface datasets to probe the spatial distribution of these smaller scale faults has given rise to a large number of outcrop based studies, allowing their intensity, connectivity and size distributions to be explored in detail. Whilst these studies have yielded an improved theoretical understanding of the style and distribution of sub-seismic scale faults, the ability to transform observations from outcrop to quantities that are relatable to reservoir volumes remains elusive. These issues arise from the fact that outcrops essentially offer a pseudo-3D window into the rock volume, making the extrapolation of surficial fault properties such as areal density (fracture length per unit area: P21), to equivalent volumetric measures (i.e. fracture area per unit volume: P32) applicable to fracture modelling extremely challenging. Here, we demonstrate an approach which harnesses advances in the extraction of 3D trace maps from surface reconstructions using calibrated image sequences, in combination with a novel semi

  2. Dry fracture method for simultaneous measurement of in-situ stress state and material properties

    Energy Technology Data Exchange (ETDEWEB)

    Serata, S. [Serata Geomechanics, Inc., Richmond, CA (United States); Oka, S.; Kikuchi, S. [JDC Corp., Tokyo (Japan)

    1996-04-01

    Based on the dry fracture principle, a computerized borehole probe has been developed to measure stress state and material properties, simultaneously. The probe is designed to obtain a series of measurements in a continuing sequence along a borehole length, without any interruptive measures, such as resetting packers, taking indentation of borehole wall, overcoming, etc. The new dry fracture probe for the single fracture method is designed to overcome the difficulties posed by its ancestor which was based on the double fracture method. The accuracy of the single fracture method is confirmed by a close agreement with the theory, FE modeling and laboratory testing.

  3. Fracture of the styloid process associated with the mandible fracture

    Directory of Open Access Journals (Sweden)

    K N Dubey

    2013-01-01

    Full Text Available Fracture of the styloid process (SP of temporal bone is an uncommon injuries. Fracture of the SP can be associated with the facial injuries including mandible fracture. However, injury to the SP may be concealed and missed diagnosis may lead to the improper or various unnecessary treatments. A rare case of SP fracture associated with the ipsilateral mandibular fracture and also the diagnostic and management considerations of the SP fracture are discussed.

  4. Medical Cost Analysis of the Osteoporotic Hip Fractures

    Directory of Open Access Journals (Sweden)

    Savaş Çamur

    2015-12-01

    Full Text Available Objective: Osteoporotic hip fractures decrease the life expectancy for 20% about 20-50% of the patients become permanently dependent in terms of walking for the rest of their life. Life expectancy is increasing in Turkey in the last 20 years. We investigated the impact of osteoporotic hip fractures which increase the morbidity and mortality on the national economy. Materials and Methods: A total of 81 patients admitted to our emergency department with the diagnosis of femur intertrochanteric fracture and femoral neck fracture between 2008 and 2012 were included in this study. We retrospectively evaluated the medical records and the medical costs of these patients from hospital information management system. Results: Of the 81 patients 32 (39.6% males and 49 (60.4% females meeting the inclusion criteria were included in this study. The mean age was 80.1 years (range, 61-103. Twenty-three (27.5% patients had femoral neck fracture and 58 (72.5% patients had intertrochanteric femur fracture. The mean length of hospital stay was 13.4 days in intertrochanteric femur fracture and 15.5 days in femoral neck fracture; average of the total days of hospitalization of all patients was 13.9 days. The average treatment cost per patient was 5,912.36 TL for intertrochanteric fractures, 5,753.00 TL for neck fractures, and 5,863.09 TL for the whole patient population. Conclusion: Hip fracture is a substantial cause of morbidity and mortality in elderly. Taking preventive measures before the fracture occurs may help to prevent this problem which has a high cost treatment and which is a substantial burden for the national economy.

  5. Isolated rib fractures in geriatric patients

    Directory of Open Access Journals (Sweden)

    Elmistekawy Elsayed

    2007-01-01

    Full Text Available Introduction: The goal of this study was to investigate the short-term outcomes in patients older than 60 years with isolated rib fractures and admitted to emergency hospital. Materials and Methods: This study included patients who were 60 years old or more and sustained blunt chest injury and had isolated rib fractures. The following data were obtained from the medical records: age, gender, number of fracture ribs, side of fracture ribs, mechanism and nature of injury, preexisting medical conditions, complications, admission to intensive care unit (ICU, need for mechanical ventilation, length of ICU and hospital stay and mortality. Results: For the study, 39 patients who were 60 years old or more and admitted to the hospital because of isolated rib fractures were enrolled. There were 28 males (71.7% and 11 females (28.3% with mean age of (66.84 ± 4.7 years. No correlation was found between comorbidities and hospital outcomes except in those who were diabetic (P-value = 0.005 and those with chronic lung disease (P-value = 0.006. Pulmonary complications were the most frequent complications encountered in those patients. Pulmonary complications were: lung contusion in 8 patients (20.5% and pulmonary infection in 6 patients (15.8%. Conclusion: Elderly patients sustaining blunt chest trauma had significant morbidity and potential for mortality.

  6. Case study: the impact of VSB fracturing

    Science.gov (United States)

    Dillon, Brian; Norris, Tim

    2008-05-01

    Yield of a Variable Shaped Beam (VSB) created photomask is directly related to the quality of the fracture. The quality of a fracture is determined by three criteria: split CDs, slivers, and fracture consistency. Split CDs of figures whose widths are under the beam's shot size affect the quality due to adding an unnecessary shot registration error. Slivers, or extremely skinny shots, are harmful because they increase write time, adversely affect lithography patterning, and subsequently can cause inspection errors. Inconsistent fracturing of identical geometry compounds these issues that affect uniformity. Testmask structures devoted to grading the impact of slivers and consistency will be created, manufactured, and measured to enable statistical analysis of fracture data. These structures will be systematically designed to cover a wide range of sliver widths and feature geometries. The mean to target will be evaluated for these test structures, and from this, impact on CD linearity and CD uniformity can be judged. The effect of slivers on write time will be discussed in a more general scope. When evaluating the impact of slivers, five criteria should be investigated: sliver length, sliver width, proximity, avoidability, and location. Each of these criteria either affect lithography or write time. Determining how to define the maximum width of a sliver is fracture algorithm dependent, but this paper gives guidelines that should ease that process. The goal is to fracture identical geometry in an identical fashion, regardless of orientation or mirroring, while making the shots as large as possible and avoiding slivers; and when avoiding a sliver is impossible, trying to embed the sliver between large shots.

  7. Statistical analysis of surface lineaments and fractures for characterizing naturally fractured reservoirs

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Genliang; George, S.A.; Lindsey, R.P.

    1997-08-01

    Thirty-six sets of surface lineaments and fractures mapped from satellite images and/or aerial photos from parts of the Mid-continent and Colorado Plateau regions were collected, digitized, and statistically analyzed in order to obtain the probability distribution functions of natural fractures for characterizing naturally fractured reservoirs. The orientations and lengths of the surface linear features were calculated using the digitized coordinates of the two end points of each individual linear feature. The spacing data of the surface linear features within an individual set were, obtained using a new analytical sampling technique. Statistical analyses were then performed to find the best-fit probability distribution functions for the orientation, length, and spacing of each data set. Twenty-five hypothesized probability distribution functions were used to fit each data set. A chi-square goodness-of-fit test was used to rank the significance of each fit. A distribution which provides the lowest chi-square goodness-of-fit value was considered the best-fit distribution. The orientations of surface linear features were best-fitted by triangular, normal, or logistic distributions; the lengths were best-fitted by PearsonVI, PearsonV, lognormal2, or extreme-value distributions; and the spacing data were best-fitted by lognormal2, PearsonVI, or lognormal distributions. These probability functions can be used to stochastically characterize naturally fractured reservoirs.

  8. Numerical Investigation on Stress Shadowing in Fluid Injection-Induced Fracture Propagation in Naturally Fractured Geothermal Reservoirs

    Science.gov (United States)

    Yoon, Jeoung Seok; Zimmermann, Günter; Zang, Arno

    2015-07-01

    In low permeability shale reservoirs, multi-stage hydraulic fracturing is largely used to increase the productivity by enlarging the stimulated rock volume. Hydraulic fracture created alters the stress field around it, and affects the subsequent fractures by the change of the stress field, in particular, mostly increased minimum principal stress at the area of subsequent fracturing. This is called stress shadow which accumulates as the fracturing stages advance from toe to heel. Hydraulic fractures generated in such altered stress field are shorter and compact with orientation deviating significantly from the far-field maximum horizontal stress orientation. This paper presents 2D discrete element-based numerical modeling of multi-stage hydraulic fracturing in a naturally fractured reservoir and investigates stress shadowing. The stress shadowing is tested with two different injection scenarios: constant and cyclic rate injections. The results show that cyclic injection tends to lower the effect of stress shadow as well as mitigates the magnitude of the induced seismicity. Another modeling case is presented to show how the stress shadow can be utilized to optimize a hydraulic fracture network in application to Groß Schönebeck geothermal reservoir, rather than being mitigated. The modeling demonstrated that the stress shadow is successfully utilized for optimizing the geothermal heat exchanger by altering the initial in situ stress field from highly anisotropic to less or even to isotropic.

  9. Hip Fractures among Older Adults

    Science.gov (United States)

    ... online training for health care providers. Learn More Hip Fractures Among Older Adults Recommend on Facebook Tweet Share ... get older. What You Can Do to Prevent Hip Fractures You can prevent hip fractures by taking steps ...

  10. discouraged by queue length

    Directory of Open Access Journals (Sweden)

    P. R. Parthasarathy

    2001-01-01

    Full Text Available The transient solution is obtained analytically using continued fractions for a state-dependent birth-death queue in which potential customers are discouraged by the queue length. This queueing system is then compared with the well-known infinite server queueing system which has the same steady state solution as the model under consideration, whereas their transient solutions are different. A natural measure of speed of convergence of the mean number in the system to its stationarity is also computed.

  11. Pneumothorax complicating isolated clavicle fracture.

    Science.gov (United States)

    Hani, Redouane; Ennaciri, Badr; Jeddi, Idriss; El Bardouni, Ahmed; Mahfoud, Mustapha; Berrada, Mohamed Saleh

    2015-01-01

    Isolated clavicle fractures are among the commonest of traumatic fractures in the emergency department. Complications of isolated clavicle fractures are rare. Pneumothorax has been described as a complication of a fractured clavicle only rarely in English literature. In all the reported cases, the pneumothorax was treated by a thoracostomy and the clavicle fracture was treated conservatively. In our case, the pneumothorax required a chest drain insertion and the clavicle fracture was treated surgically with good result.

  12. Quantitative Measurement Method for Possible Rib Fractures in Chest Radiographs

    Science.gov (United States)

    Kim, Jaeil; Kim, Sungjun; Kim, Young Jae

    2013-01-01

    Objectives This paper proposes a measurement method to quantify the abnormal characteristics of the broken parts of ribs using local texture and shape features in chest radiographs. Methods Our measurement method comprises two steps: a measurement area assignment and sampling step using a spline curve and sampling lines orthogonal to the spline curve, and a fracture-ness measurement step with three measures, asymmetry and gray-level co-occurrence matrix based measures (contrast and homogeneity). They were designed to quantify the regional shape and texture features of ribs along the centerline. The discriminating ability of our method was evaluated through region of interest (ROI) analysis and rib fracture classification test using support vector machine. Results The statistically significant difference was found between the measured values from fracture and normal ROIs; asymmetry (p rib fracture classifier, trained with the measured values in ROI analysis, detected every rib fracture from chest radiographs used for ROI analysis, but it also classified some unbroken parts of ribs as abnormal parts (8 to 17 line sets; length of each line set, 2.998 ± 2.652 mm; length of centerlines, 131.067 ± 29.460 mm). Conclusions Our measurement method, which includes a flexible measurement technique for the curved shape of ribs and the proposed shape and texture measures, could discriminate the suspicious regions of ribs for possible rib fractures in chest radiographs. PMID:24175118

  13. Pelvic compartment syndrome caused by retroperitoneal hematoma of pelvic fracture

    Institute of Scientific and Technical Information of China (English)

    ZHANG Feng-qi; ZHANG Ying-ze; PAN Jin-she; PENG A-qin; WANG Hui-juan

    2005-01-01

    @@ Retroperitoneal hematoma is an obligatory complication in pelvic ring fracture.1 In most cases, the bleeding originates from venous vessels of the presacral plexus, small arteries and veins from fracture fragments. External fixation of the pelvis can control blood loss by reducing diastasis and dramatically decreasing the volume of the pelvis. But this tamponade effect can not prevent the presence of hematoma in the adjoining retroperitoneal space. It is well known that complication of retroperitoneal hematoma is infection and sepsis.

  14. Vertebral Fracture Prediction

    DEFF Research Database (Denmark)

    2008-01-01

    Vertebral Fracture Prediction A method of processing data derived from an image of at least part of a spine is provided for estimating the risk of a future fracture in vertebraeof the spine. Position data relating to at least four neighbouring vertebrae of the spine is processed. The curvature...

  15. Radial head fracture - aftercare

    Science.gov (United States)

    ... Philadelphia, PA: Elsevier Saunders; 2015:chap 6. Prawer A. Radius and ulna fractures. In: Eiff M, Hatch R, eds. Fracture Management for Primary Care . 3rd ed. Philadelphia, PA: Elsevier Saunders; 2012:chap ... PhD, and the A.D.A.M. Editorial team. Related MedlinePlus Health ...

  16. Displaced patella fractures.

    Science.gov (United States)

    Della Rocca, Gregory J

    2013-10-01

    Displaced patella fractures often result in disruption of the extensor mechanism of the knee. An intact extensor mechanism is a requirement for unassisted gait. Therefore, operative treatment of the displaced patella fracture is generally recommended. The evaluation of the patella fracture patient includes examination of extensor mechanism integrity. Operative management of patella fractures normally includes open reduction with internal fixation, although partial patellectomy is occasionally performed, with advancement of quadriceps tendon or patellar ligament to the fracture bed. Open reduction with internal fixation has historically been performed utilizing anterior tension band wiring, although comminution of the fracture occasionally makes this fixation construct inadequate. Supplementation or replacement of the tension band wire construct with interfragmentary screws, cerclage wire or suture, and/or plate-and-screw constructs may add to the stability of the fixation construct. Arthrosis of the patellofemoral joint is very common after healing of patella fractures, and substantial functional deficits may persist long after fracture healing has occurred. Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.

  17. THORACIC SPINE FRACTURES

    Institute of Scientific and Technical Information of China (English)

    戴力扬

    2001-01-01

    Objective. To investigate the unique characteristics and treatment of thoracic spine fractures.Methods. Severty-seven patients with thoracic spine fractures were retrospectively reviewed. Of these, therewere 37 compressior fractures, 34 fracture-dislocations, 3 burst fractures and 3 burst-dislocations. Twenty-six pa-tients had a complete lesion of the spinal cord, 14 sustained a neurologically incomplete injury, and 37 wereneurologically intact. Fifty-three patients were treated nonoperatively and 24 treated operatively.Results. All patients were followed up for 2 ~ 15 years. None of the 26 patients with a complete lesion recov-ered any significant function. Of 37 neurologically intact patients, 13 had local pain although all of them re-mained normal function. Two of 14 patients with incomplete paraplegia returned to normal, 7 recovered some func-tion and 5 did not recovered.Conclusions. E ecause of the unique anatomy and biomechanics of the thoracic spine, the classification common-ly applied to thoracolumbar fractures is not suitable for thoracic fractures. Fusion and instrumentation are indicat-ed when the fractures are unstable, while patients with incomplete lesion of the spinal cord may be the candidatesfor supplemented decompression.

  18. Dependence of Upscaled Effective Permeability Upon Fracture Orientation and Connectivity in Naturally Fractured Reservoirs

    Science.gov (United States)

    Gulamali, M. Y.; Matthai, S. K.

    2007-12-01

    Although geologically informed models of hydrocarbon reservoirs are available at relatively high resolution, i.e. the pore scale, numerical reservoir simulators require descriptions at a larger scale, i.e. the grid-block scale, in order to produce exploitable information about the reservoir. This process, known as upscaling, is especially complicated, yet relevant, in the case of naturally fractured reservoirs which contain over half of the global hydrocarbon reserves, and are extremely heterogeneous, exhibiting complicated multiphase flow behaviour at all scales. In this work we study the effect of discrete fracture networks upon the upscaled effective permeability of the system, using a sophisticated numerical pressure-solver method based upon a finite element-finite volume scheme. We begin by examining an idealized scenario consisting of a single discrete fracture in two dimensions, and show how the upscaled effective permeability is a non-additive property. This investigation is extended to real fracture networks using outcrop data, where we find the upscaled effective permeability to be dependent upon the orientation and connectivity of the fracture network. Finally, we present our ideas for examining the influence of three dimensional fractures upon upscaled reservoir parameters.

  19. Origin of Permeability and Structure of Flows in Fractured Media

    Science.gov (United States)

    De Dreuzy, J.; Darcel, C.; Davy, P.; Erhel, J.; Le Goc, R.; Maillot, J.; Meheust, Y.; Pichot, G.; Poirriez, B.

    2013-12-01

    its consequence for crustal hydromechanics, Journal of Geophysical Research-Solid Earth, 115, 13. de Dreuzy, J.-R., et al. (2012a), Influence of fracture scale heterogeneity on the flow properties of three-dimensional Discrete Fracture Networks (DFN), J. Geophys. Res.-Earth Surf., 117(B11207), 21 PP. de Dreuzy, J.-R., et al. (2012b), Synthetic benchmark for modeling flow in 3D fractured media, Computers and Geosciences(0). Pichot, G., et al. (2010), A Mixed Hybrid Mortar Method for solving flow in Discrete Fracture Networks, Applicable Analysis, 89(10), 1729-1643. Pichot, G., et al. (2012), Flow simulation in 3D multi-scale fractured networks using non-matching meshes, SIAM Journal on Scientific Computing (SISC), 34(1). Figure: (a) Fracture network with a broad-range of fracture lengths. (b) Flows (log-scale) with homogeneous fractures. (c) Flows (log-scale) with heterogeneous fractures [de Dreuzy et al., 2012a]. The impact of the fracture apertures (c) is illustrated on the organization of flows.

  20. Optimization of flow modeling in fractured media with discrete fracture network via percolation theory

    Science.gov (United States)

    Donado-Garzon, L. D.; Pardo, Y.

    2013-12-01

    Fractured media are very heterogeneous systems where occur complex physical and chemical processes to model. One of the possible approaches to conceptualize this type of massifs is the Discrete Fracture Network (DFN). Donado et al., modeled flow and transport in a granitic batholith based on this approach and found good fitting with hydraulic and tracer tests, but the computational cost was excessive due to a gigantic amount of elements to model. We present in this work a methodology based on percolation theory for reducing the number of elements and in consequence, to reduce the bandwidth of the conductance matrix and the execution time of each network. DFN poses as an excellent representation of all the set of fractures of the media, but not all the fractures of the media are part of the conductive network. Percolation theory is used to identify which nodes or fractures are not conductive, based on the occupation probability or percolation threshold. In a fractured system, connectivity determines the flow pattern in the fractured rock mass. This volume of fluid is driven through connection paths formed by the fractures, when the permeability of the rock is negligible compared to the fractures. In a population of distributed fractures, each of this that has no intersection with any connected fracture do not contribute to generate a flow field. This algorithm also permits us to erase these elements however they are water conducting and hence, refine even more the backbone of the network. We used 100 different generations of DFN that were optimized in this study using percolation theory. In each of the networks calibrate hydrodynamic parameters as hydraulic conductivity and specific storage coefficient, for each of the five families of fractures, yielding a total of 10 parameters to estimate, at each generation. Since the effects of the distribution of fault orientation changes the value of the percolation threshold, but not the universal laws of classical

  1. Transphyseal Distal Humerus Fracture.

    Science.gov (United States)

    Abzug, Joshua; Ho, Christine Ann; Ritzman, Todd F; Brighton, Brian

    2016-01-01

    Transphyseal distal humerus fractures typically occur in children younger than 3 years secondary to birth trauma, nonaccidental trauma, or a fall from a small height. Prompt and accurate diagnosis of a transphyseal distal humerus fracture is crucial for a successful outcome. Recognizing that the forearm is not aligned with the humerus on plain radiographs may aid in the diagnosis of a transphyseal distal humerus fracture. Surgical management is most commonly performed with the aid of an arthrogram. Closed reduction and percutaneous pinning techniques similar to those used for supracondylar humerus fractures are employed. Cubitus varus caused by a malunion, osteonecrosis of the medial condyle, or growth arrest is the most common complication encountered in the treatment of transphyseal distal humerus fractures. A corrective lateral closing wedge osteotomy can be performed to restore a nearly normal carrying angle.

  2. Galeazzi fracture-dislocations.

    Science.gov (United States)

    Mikić, Z D

    1975-12-01

    Among 125 patients with the Galeazzi-type fracture-dislocation of the forearm, there were fourteen children and eighty-six adults with the classic Galeazzi lesion, and twenty-five patients with a special type -- fracture of both bones and dislocation of the distal radio-ulnar joint. Conservative management was successful only in children. In adults this method resulted in failure in 80 per cent of cases. The results of operative treatment were much better. The fracture fragments of the radius and the dislocation of the radio-ulnar joint in this complex injury are very unstable, especially in the lesion with fractures of the radius and ulna, and it appears that rigid internal fixation is necessary for the dislocation as well as the fracture. With combined fixation over half of the results were excellent.

  3. Dynamic fracture mechanics

    Science.gov (United States)

    Kobayashi, A. S.; Ramulu, M.

    1985-01-01

    Dynamic fracture and crack propagation concepts for ductile materials are reviewed. The equations for calculating dynamic stress integrity and the dynamic energy release rate in order to study dynamic crack propagation are provided. The stress intensity factor versus crack velocity relation is investigated. The uses of optical experimental techniques and finite element methods for fracture analyses are described. The fracture criteria for a rapidly propagating crack under mixed mode conditions are discussed; crack extension and fracture criteria under combined tension and shear loading are based on maximum circumferential stress or energy criteria such as strain energy density. The development and use of a Dugdale model and finite element models to represent crack and fracture dynamics are examined.

  4. Tibial Plateau Fractures

    DEFF Research Database (Denmark)

    Elsøe, Rasmus

    This PhD thesis reported an incidence of tibial plateau fractures of 10.3/100,000/year in a complete Danish regional population. The results reported that patients treated for a lateral tibial plateau fracture with bone tamp reduction and percutaneous screw fixation achieved a satisfactory level...... with only the subgroup Sport significantly below the age matched reference population. The thesis reports a level of health related quality of life (Eq5d) and disability (KOOS) significantly below established reference populations for patients with bicondylar tibial plateau fracture treated with a ring...... fixator, both during treatment and at 19 months following injury. In general, the thesis demonstrates that the treatment of tibial plateau fractures are challenging and that some disabilities following these fractures must be expected. Moreover, the need for further research in the area, both with regard...

  5. Dating fractures in infants

    Energy Technology Data Exchange (ETDEWEB)

    Halliday, K.E., E-mail: kath.halliday@nuh.nhs.uk [Department of Radiology, Nottingham University Hospitals, Queen' s Medical Centre, Nottingham (United Kingdom); Broderick, N.J.; Somers, J.M. [Department of Radiology, Nottingham University Hospitals, Queen' s Medical Centre, Nottingham (United Kingdom); Hawkes, R. [Department of Radiology, Paul O' Gorman Building, Bristol (United Kingdom)

    2011-11-15

    Aim: To document the timing of the appearance of the radiological features of fracture healing in a group of infants in which the date of injury was known and to assess the degree of interobserver agreement. Materials and methods: Three paediatric radiologists independently assessed 161 images of 37 long bone fractures in 31 patients aged 0-44 months. The following features were assessed: soft-tissue swelling, subperiosteal new bone formation (SPNBF), definition of fracture line, presence or absence of callus, whether callus was well or ill defined, and the presence of endosteal callus. Results: Agreement between observers was only moderate for all discriminators except SPNBF. SPNBF was invariably seen after 11 days but was uncommon before this time even in the very young. In one case SPNBF was seen at 4 days. Conclusion: With the exception of SPNBF, the criteria relied on to date fractures are either not reproducible or are poor discriminators of fracture age.

  6. Fracture network evaluation program (FraNEP): A software for analyzing 2D fracture trace-line maps

    Science.gov (United States)

    Zeeb, Conny; Gomez-Rivas, Enrique; Bons, Paul D.; Virgo, Simon; Blum, Philipp

    2013-10-01

    Fractures, such as joints, faults and veins, strongly influence the transport of fluids through rocks by either enhancing or inhibiting flow. Techniques used for the automatic detection of lineaments from satellite images and aerial photographs, LIDAR technologies and borehole televiewers significantly enhanced data acquisition. The analysis of such data is often performed manually or with different analysis software. Here we present a novel program for the analysis of 2D fracture networks called FraNEP (Fracture Network Evaluation Program). The program was developed using Visual Basic for Applications in Microsoft Excel™ and combines features from different existing software and characterization techniques. The main novelty of FraNEP is the possibility to analyse trace-line maps of fracture networks applying the (1) scanline sampling, (2) window sampling or (3) circular scanline and window method, without the need of switching programs. Additionally, binning problems are avoided by using cumulative distributions, rather than probability density functions. FraNEP is a time-efficient tool for the characterisation of fracture network parameters, such as density, intensity and mean length. Furthermore, fracture strikes can be visualized using rose diagrams and a fitting routine evaluates the distribution of fracture lengths. As an example of its application, we use FraNEP to analyse a case study of lineament data from a satellite image of the Oman Mountains.

  7. Hindfoot Valgus following Interlocking Nail Treatment for Tibial Diaphysis Fractures: Can the Fibula Be Neglected?

    Directory of Open Access Journals (Sweden)

    Metin Uzun

    2014-01-01

    Full Text Available Purpose. We evaluated whether intramedullary nail fixation for tibial diaphysis fractures with concomitant fibula fractures (except at the distal one-third level managed conservatively with an associated fibula fracture resulted in ankle deformity and assessed the impact of the ankle deformity on lower extremity function. Methods. Sixty middle one-third tibial shaft fractures with associated fibular fractures, except the distal one-third level, were included in this study. All tibial shaft fractures were anatomically reduced and fixed with interlocking intramedullary nails. Fibular fractures were managed conservatively. Hindfoot alignment was assessed clinically. Tibia and fibular lengths were compared to contralateral measurements using radiographs. Functional results were evaluated using the Knee Injury and Osteoarthritis Outcome Score (KOOS and the Foot and Ankle Disability Index Score (FADI. Results. Anatomic union, defined as equal length in operative and contralateral tibias, was achieved in 60 fractures (100%. Fibular shortening was identified in 42 fractures (68%. Mean fibular shortening was 1.2 cm (range, 0.5–2 cm. Clinical exams showed increased hindfoot valgus in 42 fractures (68%. The mean KOOS was 88.4, and the mean FADI score was 90. Conclusion. Fibular fractures in the middle or proximal one-third may need to be stabilized at the time of tibial intramedullary nail fixation to prevent development of hindfoot valgus due to fibular shortening.

  8. Influence of bone mineral density and hip geometry on the different types of hip fracture.

    Science.gov (United States)

    Li, Yizhong; Lin, Jinkuang; Cai, Siqing; Yan, Lisheng; Pan, Yuancheng; Yao, Xuedong; Zhuang, Huafeng; Wang, Peiwen; Zeng, Yanjun

    2016-01-01

    The aim of this study was to assess the influence of bone mineral density and hip geometry on the fragility fracture of femoral neck and trochanteric region. There were 95 menopausal females of age ≥ 50 years with fragility fracture of hip, including 55 cases of femoral neck fracture and 40 cases of trochanteric fracture. Another 63 non-fractured females with normal bone mineral density (BMD) were chosen as control. BMD, hip axis length, neck-shaft angle and structural parameters including cross surface area, cortical thickness and buckling ratio were detected and compared. Compared with control group, the patients with femoral neck fracture or trochanteric fractures had significantly lower BMD of femoral neck, as well as lower cross surface area and cortical thickness and higher buckling ratio in femoral neck and trochanteric region. There were no significant differences of BMD and structural parameters in the femoral neck fracture group and intertrochanteric fracture group. Hip axis length and neck-shaft angle were not significantly different among three groups. The significant changes of BMD and proximal femur geometry were present in the fragility fracture of femoral neck and trochanteric region. The different types of hip fractures cannot be explained by these changes.

  9. Analysis of Fracture in Cores from the Tuff Confining Unit beneath Yucca Flat, Nevada Test Site

    Energy Technology Data Exchange (ETDEWEB)

    Lance Prothro

    2008-03-01

    The role fractures play in the movement of groundwater through zeolitic tuffs that form the tuff confining unit (TCU) beneath Yucca Flat, Nevada Test Site, is poorly known. This is an important uncertainty, because beneath most of Yucca Flat the TCU lies between the sources of radionuclide contaminants produced by historic underground nuclear testing and the regional carbonate aquifer. To gain a better understanding of the role fractures play in the movement of groundwater and radionuclides through the TCU beneath Yucca Flat, a fracture analysis focusing on hydraulic properties was performed on conventional cores from four vertical exploratory holes in Area 7 of Yucca Flat that fully penetrate the TCU. The results of this study indicate that the TCU is poorly fractured. Fracture density for all fractures is 0.27 fractures per vertical meter of core. For open fractures, or those observed to have some aperture, the density is only 0.06 fractures per vertical meter of core. Open fractures are characterized by apertures ranging from 0.1 to 10 millimeter, and averaging 1.1 millimeter. Aperture typically occurs as small isolated openings along the fracture, accounting for only 10 percent of the fracture volume, the rest being completely healed by secondary minerals. Zeolite is the most common secondary mineral occurring in 48 percent of the fractures observed.

  10. Volume Entropy

    CERN Document Server

    Astuti, Valerio; Rovelli, Carlo

    2016-01-01

    Building on a technical result by Brunnemann and Rideout on the spectrum of the Volume operator in Loop Quantum Gravity, we show that the dimension of the space of the quadrivalent states --with finite-volume individual nodes-- describing a region with total volume smaller than $V$, has \\emph{finite} dimension, bounded by $V \\log V$. This allows us to introduce the notion of "volume entropy": the von Neumann entropy associated to the measurement of volume.

  11. Computed tomograms of blowout fracture

    Energy Technology Data Exchange (ETDEWEB)

    Ito, Haruhide; Hayashi, Minoru; Shoin, Katsuo; Hwang, Wen-Zern; Yamamoto, Shinjiro; Yonemura, Taizo

    1985-02-01

    We studied 18 cases of orbital fractures, excluding optic canal fracture. There were 11 cases of pure blowout fracture and 3 of the impure type. The other 4 cases were orbital fractures without blowout fracture. The cardinal syndromes were diplopia, enophthalmos, and sensory disturbances of the trigeminal nerve in the pure type of blowout fracture. Many cases of the impure type of blowout fracture or of orbital fracture showed black eyes or a swelling of the eyelids which masked enophthalmos. Axial and coronal CT scans demonstrated: 1) the orbital fracture, 2) the degree of enophthalmos, 3) intraorbital soft tissue, such as incarcerated or prolapsed ocular muscles, 4) intraorbital hemorrhage, 5) the anatomical relation of the orbital fracture to the lacrimal canal, the trochlea, and the trigeminal nerve, and 6) the lesions of the paranasal sinus and the intracranial cavity. CT scans play an important role in determining what surgical procedures might best be employed. Pure blowout fractures were classified by CT scans into these four types: 1) incarcerating linear fracture, 2) trapdoor fracture, 3) punched-out fracture, and 4) broad fracture. Cases with severe head injury should be examined to see whether or not blowout fracture is present. If the patients are to hope to return to society, a blowout fracture should be treated as soon as possible. (author).

  12. Geriatric hip fracture management: keys to providing a successful program.

    Science.gov (United States)

    Basu, N; Natour, M; Mounasamy, V; Kates, S L

    2016-10-01

    Hip fractures are a common event in older adults and are associated with significant morbidity, mortality and costs. This review examines the necessary elements required to implement a successful geriatric fracture program and identifies some of the barriers faced when implementing a successful program. The Geriatric Fracture Center (GFC) is a treatment model that standardizes the approach to the geriatric fracture patient. It is based on five principles: surgical fracture management; early operative intervention; medical co-management with geriatricians; patient-centered, standard order sets to employ best practices; and early discharge planning with a focus on early functional rehabilitation. Implementing a geriatric fracture program begins with an assessment of the hospital's data on hip fractures and standard care metrics such as length of stay, complications, time to surgery, readmission rates and costs. Business planning is essential along with the medical planning process. To successfully develop and implement such a program, strong physician leadership is necessary to articulate both a short- and long-term plan for implementation. Good communication is essential-those organizing a geriatric fracture program must be able to implement standardized plans of care working with all members of the healthcare team and must also be able to foster relationships both within the hospital and with other institutions in the community. Finally, a program of continual quality improvement must be undertaken to ensure that performance outcomes are improving patient care.

  13. Modeling Electric Current Flow in 3D Fractured Media

    Science.gov (United States)

    Demirel, S.; Roubinet, D.; Irving, J.

    2014-12-01

    The study of fractured rocks is extremely important in a variety of research fields and applications such as hydrogeology, hydrocarbon extraction and long-term storage of toxic waste. As fractures are highly conductive structures in comparison to the surrounding rock, their presence can be either an advantage or a drawback. For hydrocarbon extraction, fractures allow for quick and easy access to the resource whereas for toxic waste storage their presence increases the risk of leakage and migration of pollutants. In both cases, the identification of fracture network characteristics is an essential step. Recently, we have developed an approach for modeling electric current flow in 2D fractured media. This approach is based on a discrete-dual-porosity model where fractures are represented explicitly, the matrix is coarsely discretized into blocks, and current flow exchange between the fractures and matrix is analytically evaluated at the fracture-scale and integrated at the block-scale [1]. Although this approach has shown much promise and has proven its efficiency for 2D simulations, its extension to 3D remains to be addressed. To this end, we assume that fractures can be represented as two-dimensional finite planes embedded in the surrounding matrix, and we express analytically the distribution of electric potential at the fracture scale. This fracture-scale expression takes into account the electric-current-flow exchange with the surrounding matrix and flow conservation is enforced at the fracture intersections. The fracture-matrix exchange is then integrated at the matrix-block scale where the electric current flow conservation at the block boundaries is formulated with a modified finite volume method. With the objective of providing a low-computational-cost modeling approach adapted to 3D simulations in fractured media, our model is (i) validated and compared to existing modeling approaches and, (ii) used to evaluate the impact of the presence of fractures on

  14. Carbonate fracture stratigraphy: An integrated outcrop and 2D discrete element modelling study

    Science.gov (United States)

    Spence, Guy; Finch, Emma

    2013-04-01

    Constraining fracture stratigraphy is important as natural fractures control primary fluid flow in low matrix permeability naturally fractured carbonate hydrocarbon reservoirs. Away from the influence of folds and faults, stratigraphic controls are known to be the major control on fracture networks. The fracture stratigraphy of carbonate nodular-chert rhythmite successions are investigated using a Discrete Element Modelling (DEM) technique and validated against observations from outcrops. Comparisons are made to the naturally fractured carbonates of the Eocene Thebes Formation exposed in the west central Sinai of Egypt, which form reservoir rocks in the nearby East Ras Budran Field. DEM allows mechanical stratigraphy to be defined as the starting conditions from which forward numerical modelling can generate fracture stratigraphy. DEM can incorporate both stratigraphic and lateral heterogeneity, and enable mechanical and fracture stratigraphy to be characterised separately. Stratally bound stratified chert nodules below bedding surfaces generate closely spaced lateral heterogeneity in physical properties at stratigraphic mechanical interfaces. This generates extra complexity in natural fracture networks in addition to that caused by bed thickness and lithological physical properties. A series of representative geologically appropriate synthetic mechanical stratigraphic models were tested. Fracture networks generated in 15 DEM experiments designed to isolate and constrain the effects of nodular chert rhythmites on carbonate fracture stratigraphy are presented. The discrete element media used to model the elastic strengths of rocks contain 72,866 individual elements. Mechanical stratigraphies and the fracture networks generated are placed in a sequence stratigraphic framework. Nodular chert rhythmite successions are shown to be a distinct type of naturally fractured carbonate reservoir. Qualitative stratigraphic rules for predicting the distribution, lengths, spacing

  15. Focal osteoporosis defects play a key role in hip fracture.

    Science.gov (United States)

    Poole, Kenneth E S; Skingle, Linda; Gee, Andrew H; Turmezei, Thomas D; Johannesdottir, Fjola; Blesic, Karen; Rose, Collette; Vindlacheruvu, Madhavi; Donell, Simon; Vaculik, Jan; Dungl, Pavel; Horak, Martin; Stepan, Jan J; Reeve, Jonathan; Treece, Graham M

    2017-01-01

    Hip fractures are mainly caused by accidental falls and trips, which magnify forces in well-defined areas of the proximal femur. Unfortunately, the same areas are at risk of rapid bone loss with ageing, since they are relatively stress-shielded during walking and sitting. Focal osteoporosis in those areas may contribute to fracture, and targeted 3D measurements might enhance hip fracture prediction. In the FEMCO case-control clinical study, Cortical Bone Mapping (CBM) was applied to clinical computed tomography (CT) scans to define 3D cortical and trabecular bone defects in patients with acute hip fracture compared to controls. Direct measurements of trabecular bone volume were then made in biopsies of target regions removed at operation. The sample consisted of CT scans from 313 female and 40 male volunteers (158 with proximal femoral fracture, 145 age-matched controls and 50 fallers without hip fracture). Detailed Cortical Bone Maps (c.5580 measurement points on the unfractured hip) were created before registering each hip to an average femur shape to facilitate statistical parametric mapping (SPM). Areas where cortical and trabecular bone differed from controls were visualised in 3D for location, magnitude and statistical significance. Measures from the novel regions created by the SPM process were then tested for their ability to classify fracture versus control by comparison with traditional CT measures of areal Bone Mineral Density (aBMD). In women we used the surgical classification of fracture location ('femoral neck' or 'trochanteric') to discover whether focal osteoporosis was specific to fracture type. To explore whether the focal areas were osteoporotic by histological criteria, we used micro CT to measure trabecular bone parameters in targeted biopsies taken from the femoral heads of 14 cases. Hip fracture patients had distinct patterns of focal osteoporosis that determined fracture type, and CBM measures classified fracture type better than a

  16. Comparison of an Organized Geriatric Fracture Program to United States Government Data

    OpenAIRE

    Kates, Stephen L.; Blake, Deidre; Bingham, Karilee W.; Kates, Olivia S.; Mendelson, Daniel A.; Friedman, Susan M.

    2010-01-01

    Objective: This study describes the financial impact of an organized hip fracture program for elderly patients age 65 years and older. Methods: This is a retrospective study of 797 fractures in 776 consecutive patients over a 50-month period (May 2005 to July 2009) treated in an organized hip fracture program for the elderly identified from a quality management database. Financial, demographic, and quality-of-care data were collected. The length of hospital stay, in-hospital complications, an...

  17. Fracture assessment of magnetostrictive materials

    Directory of Open Access Journals (Sweden)

    M. Peron

    2017-10-01

    Full Text Available Giant magnetostrictive materials are gaining interest in the field of smart material, especially the commercially known Terfenol-D, that is an alloy made out of iron, terbium and dysprosium (Tb0.3Dy0.7Fe1.9. Since these smart materials are subjected to both mechanical loads and magnetic field during their industrial applications, an extensive characterization on the influence of a magnetic field and of defects on their fracture behavior is needed. Very few works can be found in literature about this topic and, thus, the purpose of this work is to partially fill this lack by means of three-point bending tests on single-edge pre-cracked Terfenol-D specimens. Failure loads have been measured at different loading rates and under magnetic fields of various intensities. Since giant magnetostrictive materials are very brittle, the strain energy density (SED approach has been exploited by means of couplefield finite element analyses. SED has revealed itself as a robust parameters in the assessment of the magnetic field and loading rate effects on fracture resistance, allowing also to propose a relationship between the radius of the control volume and the loading-rate

  18. Ground Wood Fiber Length Distributions

    Directory of Open Access Journals (Sweden)

    Lauri Ilmari Salminen

    2014-01-01

    Full Text Available This study considers ground wood fiber length distributions arising from pilot grindings. The empirical fiber length distributions appear to be independent of wood fiber length as well as feeding velocity. In terms of mathematics the fiber fragment distributions of ground wood pulp combine an exponential distribution for high-length fragments and a power-law distribution for smaller lengths. This implies that the fiber length distribution is influenced by the stone surface. A fragmentation-based model is presented that allows reproduction of the empirical results.

  19. Spontaneous rib fractures.

    Science.gov (United States)

    Katrancioglu, Ozgur; Akkas, Yucel; Arslan, Sulhattin; Sahin, Ekber

    2015-07-01

    Other than trauma, rib fracture can occur spontaneously due to a severe cough or sneeze. In this study, patients with spontaneous rib fractures were analyzed according to age, sex, underlying pathology, treatment, and complications. Twelve patients who presented between February 2009 and February 2011 with spontaneous rib fracture were reviewed retrospectively. The patients' data were evaluated according to anamnesis, physical examination, and chest radiographs. The ages of the patients ranged from 34 to 77 years (mean 55.91 ± 12.20 years), and 7 (58.4%) were male. All patients had severe cough and chest pain. The fractures were most frequently between 4th and 9th ribs; multiple rib fractures were detected in 5 (41.7%) patients. Eight (66.7%) patients had chronic obstructive pulmonary disease, 2 (16.7%) had bronchial asthma, and 2 (16.7%) had osteoporosis. Bone densitometry revealed a high risk of bone fracture in all patients. Patients with chronic obstructive pulmonary disease or bronchial asthma had been treated with high-dose steroids for over a year. Spontaneous rib fracture due to severe cough may occur in patients with osteoporosis, chronic obstructive pulmonary disease, or bronchial asthma, receiving long-term steroid therapy. If these patients have severe chest pain, chest radiography should be performed to check for bone lesions. © The Author(s) 2015.

  20. Percolation of fracture networks and stereology

    Science.gov (United States)

    Thovert, Jean-Francois; Mourzenko, Valeri; Adler, Pierre

    2017-04-01

    The overall properties of fractured porous media depend on the percolative character of the fracture network in a crucial way. The most important examples are permeability and transport. In a recent systematic study, a very wide range of regular, irregular and random fracture shapes is considered, in monodisperse or polydisperse networks containing fractures with different shapes and/or sizes. A simple and new model involving a dimensionless density and a new shape factor is proposed for the percolation threshold, which accounts very efficiently for the influence of the fracture shape. It applies with very good accuracy to monodisperse or moderately polydisperse networks, and provides a good first estimation in other situations. A polydispersity index is shown to control the need for a correction, and the corrective term is modelled for the investigated size distributions. Moreover, and this is crucial for practical applications, the relevant quantities which are present in the expression of the percolation threshold can all be determined from trace maps. An exact and complete set of relations can be derived when the fractures are assumed to be Identical, Isotropically Oriented and Uniformly Distributed (I2OUD). Therefore, the dimensionless density of such networks can be derived directly from the trace maps and its percolating character can be a priori predicted. These relations involve the first five moments of the trace lengths. It is clear that the higher order moments are sensitive to truncation due to the boundaries of the sampling domain. However, it can be shown that the truncation effect can be fully taken into account and corrected, for any fracture shape, size and orientation distributions, if the fractures are spatially uniformly distributed. Systematic applications of these results are made to real fracture networks that we previously analyzed by other means and to numerically simulated networks. It is important to know if the stereological results and

  1. Potential Benefits of Rib Fracture Fixation in Patients with Flail Chest and Multiple Non-flail Rib Fractures.

    Science.gov (United States)

    Qiu, Meiguang; Shi, Zhanjun; Xiao, Jun; Zhang, Xuming; Ling, Shishui; Ling, Hao

    2016-12-01

    The purpose of this study is to evaluate the potential benefits of rib fracture fixation in patients with flail chest and multiple non-flail rib fractures versus conventional treatment modalities. A retrospective reviewed study compared 86 cases which received surgical treatment between June 2009 and May 2013 to 76 cases which received conservative treatment between January 2006 and May 2009. The patients were divided into the flail chest (n = 38) and multiple non-flail rib fracture groups (n = 124). In the flail chest group, the mechanical ventilation time, ICU monitoring time, tracheostomies, thoracic deformity, and impaired pulmonary function and return to full-time employment were compared. In the multiple non-flail rib fracture group, fracture healing, visual analog scale (VAS) pain score, inpatient length of stay, atelectatic, pulmonary complications, and normal activity-returning time were compared. Patients in the flail chest operative fixation group had significantly shorter ICU stay, decreased ventilator requirements, fewer tracheostomies, less thoracic deformity and impaired pulmonary function, and more returned to full-time employment. Patients in the multiple non-flail rib fracture operative fixation had shorter hospital stay, less pain, earlier return to normal activity, more fracture healing, less atelectasis, and fewer pulmonary infections. This study demonstrates the potential benefits of surgical stabilization of flail chest and multiple non-flail rib fractures with plate fixation. When compared with conventional conservative management, operatively managed patients demonstrated improved clinical outcomes.

  2. A Fracture Mechanical Model and a Cohesive Zone Model of Interface Fracture

    DEFF Research Database (Denmark)

    Jensen, Henrik Myhre

    2006-01-01

    A comparison between the prediction of crack propagation through an adhesive interface based on a fracture mechanics approach and a cohesive zone approach is presented. Attention is focussed on predicting the shape of the crack front and the critical stress required to propagate the crack under...... quasi-static conditions. The cohesive zone model has several advantages over the fracture mechanics based model. It is easier to generalise the cohesive zone model to take into account effects such as plastic deformation in the adherends, and to take into account effects of large local curvatures...... of the interface crack front. The comparison shows a convergence of the results based on the cohesive zone model towards the results based on a fracture mechanics approach in the limit where the size of the cohesive zone becomes smaller than other relevant geometrical lengths for the problem....

  3. Fibular fracture stabilization with a guidewire as supplementary fixation in tibia fractures.

    Science.gov (United States)

    Dombroski, Derek; Scolaro, John A; Pulos, Nicholas; Beingessner, Daphne M; Dunbar, Robert; Mehta, Samir

    2012-11-01

    We present a novel technique of intramedullary fixation of the fibula using a humeral guide wire as an adjunct to tibial fixation, in the setting of tibial shaft fracture. Not only does this technique aid in determining length, alignment, and rotation of the tibial fracture, but it may also help the support of the lower extremity as whole by stabilizing the lateral column. In addition, this technique can be used to help maintain reduction of the fibula when there is concern for the soft tissues of the lower extremity secondary to swelling or injury. Our clinical case series demonstrates this safe, effective, and cost-sensitive technique to be used in the treatment of select concurrent fractures of the tibia and fibula.

  4. Identification and classification in le fort type fractures by using 2D and 3D computed tomography

    Institute of Scientific and Technical Information of China (English)

    CHEN We-jian; YANG Yun-jun; FANG Yi-ming; XU Fang-hong; ZHANG Lin; CAO Guo-quan

    2006-01-01

    Objective:To evaluate the usefulness of twodimensional (2D) and three-dimensional (3D) computed tomography (CT) in the identification and classification of Le Fort type fractures.Methods: Sixty-two patients with different types of Le Fort fractures underwent CT scanning and 3D-CT reconstruction. The data were analyzed by multiplanar reconstruction (MPR), surface shaded display (SSD) and volume rendering (VR) respectively.Results: The patients with Le Fort Ⅰ , Le Fort Ⅱfracture and Le Fort Ⅲ fracture accounted for 16.1%,14.5 % and 12.9 % respectively. The compound fractures were the most common type and accounted for 56.5 % ( n =35, 18 cases with Le Fort Ⅰ + Ⅱ fracture, 10 cases with Le Fort Ⅱ + Ⅲ fracture and 7 cases with Le Fort Ⅰ + Ⅱ + Ⅲfracture). Fifty-five cases coexisted with other fractures in maxillofacial region. 2D-CT could be used to define the tiny fractures and the deep-structure fractures more accurately compared with 3D-CT, but the real impression of Le Fort type fractures could not be correctly evaluated on 2D-CT.3D-CT could clearly demonstrate the whole shape of Le Fort type fractures and identify the classification of Le Fort fractures.Conclusions: 3D-CT is the best imaging method for the diagnosis of Le Fort type fractures and can provide valuable information of space relationship, especially for the design of treatment plan before operation.

  5. A Rare Nasal Bone Fracture: Anterior Nasal Spine Fracture

    Directory of Open Access Journals (Sweden)

    Egemen Kucuk

    2014-04-01

    Full Text Available Anterior nasal spine fractures are a quite rare type of nasal bone fractures. Associated cervical spine injuries are more dangerous than the nasal bone fracture. A case of the anterior nasal spine fracture, in a 18-year-old male was presented. Fracture of the anterior nasal spine, should be considered in the differential diagnosis of the midface injuries and also accompanying cervical spine injury should not be ignored.

  6. Veining Failure and Hydraulic Fracturing in Shales

    Science.gov (United States)

    Mighani, S.; Sondergeld, C. H.; Rai, C. S.

    2014-12-01

    During the hydraulic fracturing, the pressurized fluid creates new fractures and reactivates existing natural fractures forming a highly conductive Stimulated Reservoir Volume (SRV) around the borehole. We extend the previous work on Lyons sandstone and pyrophyllite to anisotropic shale from the Wolfcamp formation. We divide the rock anisotropy into two groups: a) conventional and b) unconventional (shaly) anisotropy. X-ray Computed Tomography (CT), compressional velocity anisotropy, and SEM analysis are used to identify three causes of anisotropy: bedding planes, clay lamination, and calcite veins. Calcite vein is a subsequently filled with calcite bonded weakly to the matrix. Velocity anisotropy and visual observations demonstrate the calcite filled veins to be mostly subparallel to the fabric direction. Brazilian tests are carried out to observe the fracture initiation and propagation under tension. High speed photography (frame rate 300,000 frame/sec) was used to capture the failure. Strain gauges and Acoustic Emission (AE) sensors recorded the deformation leading up to and during failure. SEM imaging and surface profilometry were employed to study the post-failure fracture system and failed surface topology. Fracture permeability was measured as a function of effective stress. Brazilian tests on small disks containing a centered single vein revealed the shear strength of the veins. We interpret the strain data and number, frequency, and amplitude of AE events which are correlated well with the observed fracture process zone, surface roughness, and permeability. The unpropped fracture has enhanced permeability by two orders of magnitude. The observed anisotropic tensile failure seems to have a universal trend with a minimum strength occurring at 15o orientation with respect to the loading axis. The veins at 15o orientation with respect to the loading axis were easily activated at 30% of the original failure load. The measured strength of the vein is as low as 6

  7. Hydraulic Fracture Containment in Sand

    NARCIS (Netherlands)

    Dong, Y.

    2010-01-01

    The mechanism of hydraulic fracturing in soft, high permeability material is considered fundamentally different from that in hard, low permeability rock, where a tensile fracture is created and conventional linear elastic fracture mechanics (LEFM) applies. The fracturing and associated modeling work

  8. ADVANCED FRACTURING TECHNOLOGY FOR TIGHT GAS: AN EAST TEXAS FIELD DEMONSTRATION

    Energy Technology Data Exchange (ETDEWEB)

    Mukul M. Sharma

    2005-03-01

    The primary objective of this research was to improve completion and fracturing practices in gas reservoirs in marginal plays in the continental United States. The Bossier Play in East Texas, a very active tight gas play, was chosen as the site to develop and test the new strategies for completion and fracturing. Figure 1 provides a general location map for the Dowdy Ranch Field, where the wells involved in this study are located. The Bossier and other tight gas formations in the continental Unites States are marginal plays in that they become uneconomical at gas prices below $2.00 MCF. It was, therefore, imperative that completion and fracturing practices be optimized so that these gas wells remain economically attractive. The economic viability of this play is strongly dependent on the cost and effectiveness of the hydraulic fracturing used in its well completions. Water-fracs consisting of proppant pumped with un-gelled fluid is the type of stimulation used in many low permeability reservoirs in East Texas and throughout the United States. The use of low viscosity Newtonian fluids allows the creation of long narrow fractures in the reservoir, without the excessive height growth that is often seen with cross-linked fluids. These low viscosity fluids have poor proppant transport properties. Pressure transient tests run on several wells that have been water-fractured indicate a long effective fracture length with very low fracture conductivity even when large amounts of proppant are placed in the formation. A modification to the water-frac stimulation design was needed to transport proppant farther out into the fracture. This requires suspending the proppant until the fracture closes without generating excessive fracture height. A review of fracture diagnostic data collected from various wells in different areas (for conventional gel and water-fracs) suggests that effective propped lengths for the fracture treatments are sometimes significantly shorter than those

  9. Modeling of Immiscible, Two-Phase Flows in a Natural Rock Fracture

    Energy Technology Data Exchange (ETDEWEB)

    Crandall, Dustin; Ahmadi, Goodarz; Smith, Duane H

    2009-01-01

    One potential method of geologically sequestering carbon dioxide (CO2) is to inject the gas into brine-filled, subsurface formations. Within these low-permeability rocks, fractures exist that can act as natural fluid conduits. Understanding how a less viscous fluid moves when injected into an initially saturated rock fracture is important for the prediction of CO2 transport within fractured rocks. Our study examined experimentally and numerically the motion of immiscible fluids as they were transported through models of a fracture in Berea sandstone. The natural fracture geometry was initially scanned using micro-computerized tomography (CT) at a fine volume-pixel (voxel) resolution by Karpyn et al. [1]. This CT scanned fracture was converted into a numerical mesh for two-phase flow calculations using the finite-volume solver FLUENT® and the volume-of-fluid method. Additionally, a translucent experimental model was constructed using stereolithography. The numerical model was shown to agree well with experiments for the case of a constant rate injection of air into the initially water-saturated fracture. The invading air moved intermittently, quickly invading large-aperture regions of the fracture. Relative permeability curves were developed to describe the fluid motion. These permeability curves can be used in reservoir-scale discrete fracture models for predictions of fluid motion within fractured geological formations. The numerical model was then changed to better mimic the subsurface conditions at which CO2 will move into brine saturated fractures. The different fluid properties of the modeled subsurface fluids were shown to increase the amount of volume the less-viscous invading gas would occupy while traversing the fracture.

  10. Osteosynthesis of fractures of the femur with flexible metallic intramedullary nails.

    Science.gov (United States)

    Firica, A; Troianescu, O; Petre, M

    1978-04-01

    The authors discuss their use of Ender's method in the treatment of fractures of the femur. The diameter and length of the nails depends on the type of fracture. 1) Three nails of 4 mm diameter are introduced in parallel from the medial condyle in fractures of the femoral neck; 2) 5 mm nails are used, in similar fashion, for the fixation of intertrochanteric and subtrochanteric fractures; 3) 5 mm nails are used for diaphyseal, supracondylar and intercondylar fractures, introduced in crossed fashion ("Eiffel Tower" technique) from both medial and lateral condyles. This method of fixation has proved to be extremely stable. The operation itself is quick, with no blood loss or shock. The patient can resume partial weight bearing after a week in stabilised intertrochanteric and shaft fractures, after a month in less stable types, and after three to four months in fractures of the neck of the femur. This report is based on the first 250 cases treated by this method.

  11. 欧盟页岩气水力压裂法开采生产基本准则及启示%"On minimum principles for the exploration and production of hydrocarbons using high-volume hydraulic fracturing"of EU and its Enlightenment

    Institute of Scientific and Technical Information of China (English)

    刘莎莎; 郭威

    2015-01-01

    The European shale gas reserves are abundant ,but technology is not good .Considering the potential impact of security for public health and the environment caused by hydraulic fracturing technology , the European Commission issued"on minimum principles for the exploration and production of hydrocarbons using high-volume hydraulic fracturing" (2014/70/EU ) in 2014 January .To regulate the shale gas development from the aspects of environmental protection ,basic environmental data monitoring ,exploration and exploitation of choice ,operating norms ,substance use and supervision measures .As the Similar to the EU ,the future we should learn from the EU experience ,accelerate the formulation of China's shale gas development standard ,promoting the formation of shale gas development management system which conforms to our country national condition .%欧盟页岩气储量丰富 ,但技术有限 ,考虑到水力压裂技术所带来的对公众健康和环境安全的潜在影响 ,欧盟委员会于2014年1月发布了《页岩气水力压裂法开采生产基本准则建议案》 ,从环境维护、基础环境数据监测、勘探与开采地选择、操作规范、物质使用及监管措施等方面对页岩气开发加以规范.我国页岩气利用前景与问题与欧盟类似 ,未来应借鉴欧盟经验 ,加快我国页岩气开发标准规范的制定 ,推进形成符合我国国情的页岩气开发管理制度.

  12. Three-phase flow simulations in discrete fracture networks

    Science.gov (United States)

    Geiger, S.; Niessner, J.; Matthai, S. K.; Helmig, R.

    2006-12-01

    Fractures are often the key conduits for fluid flow in otherwise low permeability rocks. Their presence in hydrocarbon reservoirs leads to complex production histories, unpredictable coupling of wells, rapidly changing flow rates, possibly early water breakthrough, and low final recovery. Recently, it has been demonstrated that a combination of finite volume and finite element discretization is well suited to model incompressible, immiscible two-phase flow in 3D discrete fracture networks (DFN) representing complexly fractured rocks. Such an approach has been commercialized in Golder Associates' FracMan Reservoir Edition software. For realistic reservoir simulations, however, it would be desirable if a third compressible gas phase can be included which is often present at reservoir conditions. Here we present the extension of an existing node-centred finite volume - finite element (FEFV) discretization for the efficient and accurate simulations of three-component - three-phase flow in geologically realistic representations of fractured porous media. Two possible types of fracture networks can be used: In 2D, they are detailed geometrical representations of fractured rock masses mapped in field studies. In 3D, they are geologically constrained, stochastically generated discrete fracture networks. Flow and transport can be simulated for fractures only or for fractures and matrix combined. The governing equations are solved decoupled using an implicit-pressure, explicit-saturation (IMPES) approach. Flux and concentration terms can be treated with higher-order accuracy in the finite volume scheme to preserve shock fronts. The method is locally mass conservative and works on unstructured, spatially refined grids. Flash calculations are carried out by a new description of the Black-Oil model. Capillary and gravity effects are included in this formulation. The robustness and accuracy of this formulation is shown in several applications. First, grid convergence is

  13. Hydraulic properties of fracture networks; Analyse des proprietes hydrauliques des reseaux de fractures: discussion des modeles d'ecoulement compatibles avec les principales proprietes geometriques

    Energy Technology Data Exchange (ETDEWEB)

    Dreuzy, J.R. de

    1999-12-15

    Fractured medium are studied in the general framework of oil and water supply and more recently for the underground storage of high level nuclear wastes. As fractures are generally far more permeable than the embedding medium, flow is highly channeled in a complex network of fractures. The complexity of the network comes from the broad distributions of fracture length and permeability at the fracture scale and appears through the increase of the equivalent permeability at the network scale. The goal of this thesis is to develop models of fracture networks consistent with both local-scale and global-scale observations. Bidimensional models of fracture networks display a wide variety of flow structures ranging from the sole permeable fracture to the equivalent homogeneous medium. The type of the relevant structure depends not only on the density and the length and aperture distributions but also on the observation scale. In several models, a crossover scale separates complex structures highly channeled from more distributed and homogeneous-like flow patterns at larger scales. These models, built on local characteristics and validated by global properties, have been settled in steady state. They have also been compared to natural well test data obtained in Ploemeur (Morbihan) in transient state. The good agreement between models and data reinforces the relevance of the models. Once validated and calibrated, the models are used to estimate the global tendencies of the main flow properties and the risk associated with the relative lack of data on natural fractures media. (author)

  14. Paediatric talus fracture.

    LENUS (Irish Health Repository)

    Byrne, Ann-Maria

    2012-01-01

    Paediatric talus fractures are rare injuries resulting from axial loading of the talus against the anterior tibia with the foot in dorsiflexion. Skeletally immature bone is less brittle, with higher elastic resistance than adult bone, thus the paediatric talus can sustain higher forces before fractures occur. However, displaced paediatric talus fractures and those associated with high-energy trauma have been associated with complications including avascular necrosis, arthrosis, delayed union, neurapraxia and the need for revision surgery. The authors present the rare case of a talar neck fracture in a skeletally immature young girl, initially missed on radiological review. However, clinical suspicion on the part of the emergency physician, repeat examination and further radiographic imaging revealed this rare paediatric injury.

  15. Geothermal Ultrasonic Fracture Imager

    Energy Technology Data Exchange (ETDEWEB)

    Patterson, Doug [Baker-Hughes Oilfield Operation Inc., Houston, TX (United States); Leggett, Jim [Baker-Hughes Oilfield Operation Inc., Houston, TX (United States)

    2013-07-29

    The Geothermal Ultrasonic Fracture Imager project has a goal to develop a wireline ultrasonic imager that is capable of operating in temperatures up to 300°C (572°F) and depths up to 10 km (32,808 ft). This will address one of the critical needs in any EGS development of understanding the hydraulic flow paths in the reservoir. The ultrasonic imaging is well known in the oil and gas industry as one of the best methods for fracture evaluation; providing both high resolution and complete azimuthal coverage of the borehole. This enables fracture detection and characterization, both natural and induced, providing information as to their location, dip direction and dip magnitude. All of these factors are critical to fully understand the fracture system to enable the optimization of the thermal drainage through injectors and producers in a geothermal resource.

  16. Clavicle Fracture (Broken Collarbone)

    Science.gov (United States)

    ... Bahk MS, Kuhn JE, Galatz LM, Connor PM, Williams GR: Acromioclavicular and sternoclavicular injuries and cla- vicular, ... Orthopaedic Surgeons. .org Clavicle Fracture cont. Rehabilitation Specific exercises will help restore movement and strengthen your shoulder. ...

  17. Proximal femoral fractures

    DEFF Research Database (Denmark)

    Palm, Henrik; Teixidor, Jordi

    2015-01-01

    BACKGROUND: In hip fracture surgery, the exact choice of implant often remains somewhat unclear for the individual surgeon, but the growing literature consensus has enabled publication of evidence-based surgical treatment pathways. The aim of this article was to review author pathways and national...... guidelines for hip fracture surgery and discuss a method for future pathway/guideline implementation and evaluation. METHODS: By a PubMed search in March 2015 six studies of surgical treatment pathways covering all types of proximal femoral fractures with publication after 1995 were identified. Also we...... searched the homepages of the national heath authorities and national orthopedic societies in West Europe and found 11 national or regional (in case of no national) guidelines including any type of proximal femoral fracture surgery. RESULTS: Pathway consensus is outspread (internal fixation for un...

  18. Role of geomechanically grown fractures on dispersive transport in heterogeneous geological formations

    KAUST Repository

    Nick, H. M.

    2011-11-04

    A second order in space accurate implicit scheme for time-dependent advection-dispersion equations and a discrete fracture propagation model are employed to model solute transport in porous media. We study the impact of the fractures on mass transport and dispersion. To model flow and transport, pressure and transport equations are integrated using a finite-element, node-centered finite-volume approach. Fracture geometries are incrementally developed from a random distributions of material flaws using an adoptive geomechanical finite-element model that also produces fracture aperture distributions. This quasistatic propagation assumes a linear elastic rock matrix, and crack propagation is governed by a subcritical crack growth failure criterion. Fracture propagation, intersection, and closure are handled geometrically. The flow and transport simulations are separately conducted for a range of fracture densities that are generated by the geomechanical finite-element model. These computations show that the most influential parameters for solute transport in fractured porous media are as follows: fracture density and fracture-matrix flux ratio that is influenced by matrix permeability. Using an equivalent fracture aperture size, computed on the basis of equivalent permeability of the system, we also obtain an acceptable prediction of the macrodispersion of poorly interconnected fracture networks. The results hold for fractures at relatively low density. © 2011 American Physical Society.

  19. Numerical modeling of the effects of roughness on flow and eddy formation in fractures

    Directory of Open Access Journals (Sweden)

    Scott Briggs

    2017-02-01

    Full Text Available The effect of roughness on flow in fractures was investigated using lattice Boltzmann method (LBM. Simulations were conducted for both statistically generated hypothetical fractures and a natural dolomite fracture. The effect of increasing roughness on effective hydraulic aperture, Izbash and Forchheimer parameters with increasing Reynolds number (Re ranging from 0.01 to 500 was examined. The growth of complex flow features, such as eddies arising near the fracture surface, was directly associated with changes in surface roughness. Rapid eddy growth above Re values of 1, followed by less rapid growth at higher Re values, suggested a three-zone nonlinear model for flow in rough fractures. This three-zone model, relating effective hydraulic conductivity to Re, was also found to be appropriate for the simulation of water flow in the natural dolomite fracture. Increasing fracture roughness led to greater eddy volumes and lower effective hydraulic conductivities for the same Re values.

  20. Optimization of Multiple Hydraulically Fractured Horizontal Wells in Unconventional Gas Reservoirs

    Directory of Open Access Journals (Sweden)

    Wei Yu

    2013-01-01

    Full Text Available Accurate placement of multiple horizontal wells drilled from the same well pad plays a critical role in the successful economical production from unconventional gas reservoirs. However, there are high cost and uncertainty due to many inestimable and uncertain parameters such as reservoir permeability, porosity, fracture spacing, fracture half-length, fracture conductivity, gas desorption, and well spacing. In this paper, we employ response surface methodology to optimize multiple horizontal well placement to maximize Net Present Value (NPV with numerically modeling multistage hydraulic fractures in combination with economic analysis. This paper demonstrates the accuracy of numerical modeling of multistage hydraulic fractures for actual Barnett Shale production data by considering the gas desorption effect. Six uncertain parameters, such as permeability, porosity, fracture spacing, fracture half-length, fracture conductivity, and distance between two neighboring wells with a reasonable range based on Barnett Shale information, are used to fit a response surface of NPV as the objective function and to finally identify the optimum design under conditions of different gas prices based on NPV maximization. This integrated approach can contribute to obtaining the optimal drainage area around the wells by optimizing well placement and hydraulic fracturing treatment design and provide insight into hydraulic fracture interference between single well and neighboring wells.

  1. Fracture Behavior under Impact.

    Science.gov (United States)

    1982-07-01

    discussed for the different loading rates ob- tai ned . 1. Introduction In static fracture mechanics crack tip stress intensity factors can easi- - ly...deviation to the left or to the right hand side of the original crack path was observed. Herrmann [151 speculated that this behavior results from stress...Materials’ Draft 2c, American Society for Testing and Materials, Philadelphia, .. ,-- 1980. 15. Herrmann , G., "Dynamic Fracture of Beams in Bending

  2. Relative permeability through fractures

    Energy Technology Data Exchange (ETDEWEB)

    Diomampo, Gracel, P.

    2001-08-01

    The mechanism of two-phase flow through fractures is of importance in understanding many geologic processes. Currently, two-phase flow through fractures is still poorly understood. In this study, nitrogen-water experiments were done on both smooth and rough parallel plates to determine the governing flow mechanism for fractures and the appropriate methodology for data analysis. The experiments were done using a glass plate to allow visualization of flow. Digital video recording allowed instantaneous measurement of pressure, flow rate and saturation. Saturation was computed using image analysis techniques. The experiments showed that gas and liquid phases flow through fractures in nonuniform separate channels. The localized channels change with time as each phase path undergoes continues breaking and reforming due to invasion of the other phase. The stability of the phase paths is dependent on liquid and gas flow rate ratio. This mechanism holds true for over a range of saturation for both smooth and rough fractures. In imbibition for rough-walled fractures, another mechanism similar to wave-like flow in pipes was also observed. The data from the experiments were analyzed using Darcy's law and using the concept of friction factor and equivalent Reynold's number for two-phase flow. For both smooth- and rough-walled fractures a clear relationship between relative permeability and saturation was seen. The calculated relative permeability curves follow Corey-type behavior and can be modeled using Honarpour expressions. The sum of the relative permeabilities is not equal one, indicating phase interference. The equivalent homogeneous single-phase approach did not give satisfactory representation of flow through fractures. The graphs of experimentally derived friction factor with the modified Reynolds number do not reveal a distinctive linear relationship.

  3. Atomistic simulations of fracture

    Energy Technology Data Exchange (ETDEWEB)

    Farkas, D. [Virginia Polytechnic Inst. and State Univ., Blacksburg, VA (United States). Dept. of Materials Science and Engineering

    1997-12-31

    Embedded atom interaction potentials are used to simulate the atomistic aspects of the fracture process. Simulations are presented for the behavior of cracks in pure metals and intermetallics, near the Griffith condition. The materials considered include Fe, Cu, Ni as well as Fe, Ni, Co, and Ti aluminides. The work focuses on the comparative study of fracture behavior in the different materials. The role of the atomic relaxation at the crack tip and of lattice trapping phenomena is analyzed.

  4. Science of Fracture.

    Science.gov (United States)

    1980-10-22

    Fracture Set-Up .............. 163 Dr. Jan T. Lindt 4.i0 Fracture in Fully Plastic Bodies ............................... 171 Dr. Howard Kuhn iii I...Benthem’s results and results obtained by 15 Bazant and Estenssoro (12) who used a finite element method of determining critical eigenvalues. Each of...14) is made by Benthem in (10) and (11) and only che sentence quoted above made by Bazant and Estenssoro (12). This is unfortunate since constructive

  5. Condylar restoration after early TMJ fractures and functional appliance therapy. Part II: Muscle evaluation.

    Science.gov (United States)

    Kahl-Nieke, B; Fischbach, R

    1999-01-01

    The aim of this study was to analyze and to describe the condition of the lateral pterygoid muscle during and after functional appliance therapy in children who had sustained condylar fractures. The treatment group consisted of 19 patients with an average age of 13.4 years, who had sustained a unilateral fracture at an average age of 8.4 years and had been treated functionally for 6 to 8 months. Muscle condition was assessed through axial soft tissue description. The volume and density of the lateral pterygoid muscle were measured in both groups and were compared on the basis of sex, age and fracture type. 74% of the patients in the follow-up group showed muscle differences of more than 10% between the 2 sides. In 2/3 of these patients the lateral pterygoid of the fracture side was 13 to 69% smaller. The volumes of the contralateral pterygoid muscles in the 2 patient groups differed by 10% on the basis of sex. Both in the treatment group and in the follow-up group the volume difference between the healthy and fractured side was as high as 70% depending on localization and type of fracture. Deep fractures and fractures with complete dislocation of the condyle evoked the most serious reduction in muscle volume.

  6. Hydraulic fracturing water use variability in the United States and potential environmental implications

    Science.gov (United States)

    Gallegos, Tanya J.; Varela, Brian A.; Haines, Seth S.; Engle, Mark A.

    2015-01-01

    Until now, up-to-date, comprehensive, spatial, national-scale data on hydraulic fracturing water volumes have been lacking. Water volumes used (injected) to hydraulically fracture over 263,859 oil and gas wells drilled between 2000 and 2014 were compiled and used to create the first U.S. map of hydraulic fracturing water use. Although median annual volumes of 15,275 m3 and 19,425 m3 of water per well was used to hydraulically fracture individual horizontal oil and gas wells, respectively, in 2014, about 42% of wells were actually either vertical or directional, which required less than 2600 m3 water per well. The highest average hydraulic fracturing water usage (10,000−36,620 m3 per well) in watersheds across the United States generally correlated with shale-gas areas (versus coalbed methane, tight oil, or tight gas) where the greatest proportion of hydraulically fractured wells were horizontally drilled, reflecting that the natural reservoir properties influence water use. This analysis also demonstrates that many oil and gas resources within a given basin are developed using a mix of horizontal, vertical, and some directional wells, explaining why large volume hydraulic fracturing water usage is not widespread. This spatial variability in hydraulic fracturing water use relates to the potential for environmental impacts such as water availability, water quality, wastewater disposal, and possible wastewater injection-induced earthquakes.

  7. Hydraulic fracturing water use variability in the United States and potential environmental implications

    Science.gov (United States)

    Gallegos, Tanya J.; Varela, Brian A.; Haines, Seth S.; Engle, Mark A.

    2015-07-01

    Until now, up-to-date, comprehensive, spatial, national-scale data on hydraulic fracturing water volumes have been lacking. Water volumes used (injected) to hydraulically fracture over 263,859 oil and gas wells drilled between 2000 and 2014 were compiled and used to create the first U.S. map of hydraulic fracturing water use. Although median annual volumes of 15,275 m3 and 19,425 m3 of water per well was used to hydraulically fracture individual horizontal oil and gas wells, respectively, in 2014, about 42% of wells were actually either vertical or directional, which required less than 2600 m3 water per well. The highest average hydraulic fracturing water usage (10,000-36,620 m3 per well) in watersheds across the United States generally correlated with shale-gas areas (versus coalbed methane, tight oil, or tight gas) where the greatest proportion of hydraulically fractured wells were horizontally drilled, reflecting that the natural reservoir properties influence water use. This analysis also demonstrates that many oil and gas resources within a given basin are developed using a mix of horizontal, vertical, and some directional wells, explaining why large volume hydraulic fracturing water usage is not widespread. This spatial variability in hydraulic fracturing water use relates to the potential for environmental impacts such as water availability, water quality, wastewater disposal, and possible wastewater injection-induced earthquakes.

  8. Effect of isolated fractures on accelerated flow in unsaturated porous rock

    Science.gov (United States)

    Su, G.W.; Nimmo, J.R.; Dragila, M.I.

    2003-01-01

    Fractures that begin and end in the unsaturated zone, or isolated fractures, have been ignored in previous studies because they were generally assumed to behave as capillary barriers and remain nonconductive. We conducted a series of experiments using Berea sandstone samples to examine the physical mechanisms controlling flow in a rock containing a single isolated fracture. The input fluxes and fracture orientation were varied in these experiments. Visualization experiments using dyed water in a thin vertical slab of rock were conducted to identify flow mechanisms occurring due to the presence of the isolated fracture. Two mechanisms occurred: (1) localized flow through the rock matrix in the vicinity of the isolated fracture and (2) pooling of water at the bottom of the fracture, indicating the occurrence of film flow along the isolated fracture wall. These mechanisms were observed at fracture angles of 20 and 60 degrees from the horizontal, but not at 90 degrees. Pooling along the bottom of the fracture was observed over a wider range of input fluxes for low-angled isolated fractures compared to high-angled ones. Measurements of matrix water pressures in the samples with the 20 and 60 degree fractures also demonstrated that preferential flow occurred through the matrix in the fracture vicinity, where higher pressures occurred in the regions where faster flow was observed in the visualization experiments. The pooling length at the terminus of a 20 degree isolated fracture was measured as a function of input flux. Calculations of the film flow rate along the fracture were made using these measurements and indicated that up to 22% of the flow occurred as film flow. These experiments, apparently the first to consider isolated fractures, demonstrate that such features can accelerate flow through the unsaturated zone and should be considered when developing conceptual models.

  9. Prevention of hip fractures.

    Science.gov (United States)

    Meunier, P J

    1993-11-30

    For a 50-year old Caucasian woman today, the risk of a hip fracture over her remaining life-time is about 17%. Tomorrow the situation will clearly be worse because the continuous increase in life expectancy will cause a three-fold increase in worldwide fracture incidence over the next 60 years. Through diagnostic bone mass measurements at the hip and assessment of biochemical parameters, a great deal has been learned in recent years about reduction of hip fracture risk. Preventive strategies are based on prevention of falls, use of hip protectors, and prevention of bone fragility. The latter includes the optimization of peak bone mass during childhood, postmenopausal estrogen replacement therapy, and also late prevention consisting in reversing senile secondary hyperparathyroidism, which plays an important role in the decrease of skeletal strength. This secondary hyperparathyroidism, which results from both vitamin D insufficiency and low calcium intake, is preventable with vitamin D3 and calcium supplements. They have recently been shown capable of providing effective prevention of hip fractures in elderly women living in nursing homes, with a reduction of about 25% in the number of hip fractures noted in a 3-year controlled study in 3,270 women (intention-to-treat analysis). In conclusion, it is never too early to reduce the risk of osteoporosis and never too late to prevent hip fractures.

  10. FRACTURING FLUID CHARACTERIZATION FACILITY

    Energy Technology Data Exchange (ETDEWEB)

    Subhash Shah

    2000-08-01

    Hydraulic fracturing technology has been successfully applied for well stimulation of low and high permeability reservoirs for numerous years. Treatment optimization and improved economics have always been the key to the success and it is more so when the reservoirs under consideration are marginal. Fluids are widely used for the stimulation of wells. The Fracturing Fluid Characterization Facility (FFCF) has been established to provide the accurate prediction of the behavior of complex fracturing fluids under downhole conditions. The primary focus of the facility is to provide valuable insight into the various mechanisms that govern the flow of fracturing fluids and slurries through hydraulically created fractures. During the time between September 30, 1992, and March 31, 2000, the research efforts were devoted to the areas of fluid rheology, proppant transport, proppant flowback, dynamic fluid loss, perforation pressure losses, and frictional pressure losses. In this regard, a unique above-the-ground fracture simulator was designed and constructed at the FFCF, labeled ''The High Pressure Simulator'' (HPS). The FFCF is now available to industry for characterizing and understanding the behavior of complex fluid systems. To better reflect and encompass the broad spectrum of the petroleum industry, the FFCF now operates under a new name of ''The Well Construction Technology Center'' (WCTC). This report documents the summary of the activities performed during 1992-2000 at the FFCF.

  11. [Subtrochanteric femoral fractures].

    Science.gov (United States)

    Ulmar, B; Simon, S; Eschler, A; Mittlmeier, T

    2013-12-01

    Subtrochanteric femoral fractures are proximal femoral fractures which are located between the trochanter minor and an area of 3 cm below the minor trochanter on the femoral shaft. About 10-15% of all proximal femoral fractures correspond to this fracture site. Elderly or geriatric patients are generally affected and the injury is often the result of a fall in the home, while high-energy trauma is the cause in a small group of generally younger patients. Clinical evaluation of the affected extremity shows disability of axial weight-bearing and pain during compression and rotation of the hip joint. Basic diagnostics include conventional x-rays of the injured femur in the anterior-posterior and lateral planes. These subtrochanteric femoral fractures are almost always treated surgically due to the inherent high degree of instability. The main goals of surgical intervention are to achieve anatomic fracture reduction and primary full weight-bearing stability of the corresponding leg. Intramedullary interlocking nails are used for primary treatment, while extramedullary implants are often used in revision surgery. Early mobilization and intensive respiratory exercises are necessary to prevent early postoperative complications.

  12. Fracture toughness of graphene.

    Science.gov (United States)

    Zhang, Peng; Ma, Lulu; Fan, Feifei; Zeng, Zhi; Peng, Cheng; Loya, Phillip E; Liu, Zheng; Gong, Yongji; Zhang, Jiangnan; Zhang, Xingxiang; Ajayan, Pulickel M; Zhu, Ting; Lou, Jun

    2014-04-29

    Perfect graphene is believed to be the strongest material. However, the useful strength of large-area graphene with engineering relevance is usually determined by its fracture toughness, rather than the intrinsic strength that governs a uniform breaking of atomic bonds in perfect graphene. To date, the fracture toughness of graphene has not been measured. Here we report an in situ tensile testing of suspended graphene using a nanomechanical device in a scanning electron microscope. During tensile loading, the pre-cracked graphene sample fractures in a brittle manner with sharp edges, at a breaking stress substantially lower than the intrinsic strength of graphene. Our combined experiment and modelling verify the applicability of the classic Griffith theory of brittle fracture to graphene. The fracture toughness of graphene is measured as the critical stress intensity factor of and the equivalent critical strain energy release rate of 15.9 J m(-2). Our work quantifies the essential fracture properties of graphene and provides mechanistic insights into the mechanical failure of graphene.

  13. Hyperuniformity disorder length spectroscopy for extended particles

    Science.gov (United States)

    Durian, D. J.

    2017-09-01

    The concept of a hyperuniformity disorder length h was recently introduced for analyzing volume fraction fluctuations for a set of measuring windows [Chieco et al., Phys. Rev. E 96, 032909 (2017)., 10.1103/PhysRevE.96.032909]. This length permits a direct connection to the nature of disorder in the spatial configuration of the particles and provides a way to diagnose the degree of hyperuniformity in terms of the scaling of h and its value in comparison with established bounds. Here, this approach is generalized for extended particles, which are larger than the image resolution and can lie partially inside and partially outside the measuring windows. The starting point is an expression for the relative volume fraction variance in terms of four distinct volumes: that of the particle, the measuring window, the mean-squared overlap between particle and region, and the region over which particles have nonzero overlap with the measuring window. After establishing limiting behaviors for the relative variance, computational methods are developed for both continuum and pixelated particles. Exact results are presented for particles of special shape and for measuring windows of special shape, for which the equations are tractable. Comparison is made for other particle shapes, using simulated Poisson patterns. And the effects of polydispersity and image errors are discussed. For small measuring windows, both particle shape and spatial arrangement affect the form of the variance. For large regions, the variance scaling depends only on arrangement but particle shape sets the numerical proportionality. The combined understanding permit the measured variance to be translated to the spectrum of hyperuniformity lengths versus region size, as the quantifier of spatial arrangement. This program is demonstrated for a system of nonoverlapping particles at a series of increasing packing fractions as well as for an Einstein pattern of particles with several different extended shapes.

  14. Gingival contour and clinical crown length: their effect on the esthetic appearance of maxillary anterior teeth.

    Science.gov (United States)

    Kokich, V G; Nappen, D L; Shapiro, P A

    1984-08-01

    Fractured, congenitally missing, or avulsed maxillary incisors can often jeopardize the esthetic appearance of the remaining maxillary anterior teeth after orthodontic treatment. In many cases the unesthetic appearance is related to the irregular clinical crown lengths of either the fractured teeth or those that have been substituted for the missing teeth. The results of five cases with either fractured or traumatically avulsed central incisors are reported. Selective tooth intrusion and restorative techniques were used during the finishing stages of orthodontic treatment to improve the final esthetic result. The advantages and disadvantages of the intrusion technique are discussed.

  15. Hydraulic Fracture Growth in a Layered Formation based on Fracturing Experiments and Discrete Element Modeling

    Science.gov (United States)

    Yushi, Zou; Xinfang, Ma; Tong, Zhou; Ning, Li; Ming, Chen; Sihai, Li; Yinuo, Zhang; Han, Li

    2017-09-01

    Hydraulic fracture (HF) height containment tends to occur in layered formations, and it significantly influences the entire HF geometry or the stimulated reservoir volume. This study aims to explore the influence of preexisting bedding planes (BPs) on the HF height growth in layered formations. Laboratory fracturing experiments were performed to confirm the occurrence of HF height containment in natural shale that contains multiple weak and high-permeability BPs under triaxial stresses. Numerical simulations were then conducted to further illustrate the manner in which vertical stress, BP permeability, BP density(or spacing), pump rate, and fluid viscosity control HF height growth using a 3D discrete element method-based fracturing model. In this model, the rock matrix was considered transversely isotropic and multiple BPs can be explicitly represented. Experimental and numerical results show that the vertically growing HF tends to be limited by multi-high-permeability BPs, even under higher vertical stress. When the vertically growing HF intersects with the multi-high-permeability BPs, the injection pressure will be sharply reduced. If a low pumping rate or a low-viscosity fluid is used, the excess fracturing fluid leak-off into the BPs obviously decreases the rate of pressure build up, which will then limit the growth of HF. Otherwise, a higher pumping rate and/or a higher viscosity will reduce the leak-off time and fluid volume, but increase the injection pressure to drive the HF to grow and to penetrate through the BPs.

  16. Importance of greenstick lamina fractures in low lumbar burst fractures

    Science.gov (United States)

    Ersozlu, S.; Aydinli, U.

    2006-01-01

    Lumbar burst fractures (L3–L5) represent a small percentage of all spinal fractures. The treatment of fractures involving the lumbar spine has been controversial. Lamina fractures may be complete or of the greenstick type. Dural tears and nerve root entrapment may accompany these lamina fractures. The aim of this retrospective study was to determine the incidence of dural tear in patients who had lumbar burst fractures with greenstick lamina fractures and the importance of these lamina fractures when choosing the optimum treatment. Twenty-six patients with 28 lumbar burst fractures were treated from 1995 through 2002. The average follow-up was 60 months (range 32–110 months). The male to female ratio was 21:5 and the mean age was 37 years (17–64). Dural tear was detected in seven (25%) out of 28 burst fractures. The functional outcome of the entire study group was assessed using the Smiley-Webster Scale. Good to excellent results were obtained in 24 (92%) of 26 patients. Lumbar burst fractures with greenstick lamina fractures occur mostly in the L2–L4 area. In the surgical treatment, any reduction manoeuvre will close the fracture and crush the entrapped neural elements. Therefore, it may be better to explore the greenstick lamina fracture whether there is any neural entrapment or not, before any reduction manoeuvre is attempted. PMID:16501977

  17. Synkinematic quartz cementation in partially open fractures in sandstones

    Science.gov (United States)

    Ukar, Estibalitz; Laubach, Stephen E.; Fall, Andras; Eichhubl, Peter

    2014-05-01

    Faults and networks of naturally open fractures can provide open conduits for fluid flow, and may play a significant role in hydrocarbon recovery, hydrogeology, and CO2 sequestration. However, sandstone fracture systems are commonly infilled, at least to some degree, by quartz cement, which can stiffen and occlude fractures. Such cement deposits can systematically reduce the overall permeability enhancement due to open fractures (by reducing open fracture length) and result in permeability anisotropies. Thus, it is important to identify the factors that control the precipitation of quartz in fractures in order to identify potential fluid conduits under the present-day stress field. In many sandstones, quartz nucleates syntaxially on quartz grain or cement substrate of the fracture wall, and extends between fracture walls only locally, forming pillars or bridges. Scanning electron microscope cathodoluminescence (SEM-CL) images reveal that the core of these bridges are made up of bands of broken and resealed cement containing wall-parallel fluid inclusion planes. The fluid inclusion-rich core is usually surrounded by a layer of inclusion-poor clear quartz that comprises the lateral cement. Such crack-seal textures indicate that this phase was precipitating while the fractures were actively opening (synkinematic growth). Rapid quartz accumulation is generally believed to require temperatures of 80°C or more. Fluid inclusion thermometry and Raman spectroscopy of two-phase aqueous fluid-inclusions trapped in crack-seal bands may be used to track the P-T-X evolution of pore fluids during fracture opening and crack-seal cementation of quartz. Quartz cement bridges across opening mode fractures in the Cretaceous Travis Peak Formation of the tectonically quiescent East Texas Basin indicate individual fractures opened over a 48 m.y. time span at rates of 16-23 µm/m.y. Similarly, the Upper Cretaceous Mesaverde Group in the Piceance Basin, Colorado contains fractures that

  18. A new post-frac evaluation method for shale gas wells based on fracturing curves

    Directory of Open Access Journals (Sweden)

    Xiaobing Bian

    2016-03-01

    Full Text Available Post-fracturing evaluation by using limited data is of great significance to continuous improvement of the fracturing programs. In this paper, a fracturing curve was divided into two stages (i.e., prepad fluid injection and main fracturing so as to further understand the parameters of reservoirs and artificial fractures. The brittleness and plasticity of formations were qualitatively identified by use of the statistics of formation fracture frequency, and average pressure dropping range and rate during the prepad fluid injection. The composite brittleness index was quantitatively calculated by using the energy zones in the process of fracturing. It is shown from the large-scale true triaxial physical simulation results that the complexity of fractures is reflected by the pressure fluctuation frequency and amplitude in the main fracturing curve, and combined with the brittleness and plasticity of formations, the fracture morphology far away from the well can be diagnosed. Well P, a shale gas well in SE Chongqing, was taken as an example for post-fracturing evaluation. It is shown that the shale beds are of stronger heterogeneity along the extension directions of horizontal wells, and with GR 260 API as the dividing line between brittleness and plasticity in this area, complex fracture systems tend to form in brittleness-prone formations. In Well P, half of the fractures are single fractures, so it is necessary to carry out fine subsection and turnaround fracturing so as to improve development effects. This paper provides a theoretical basis for improving the fracturing well design and increasing the effective stimulated volume in this area.

  19. Fractured reservoir discrete feature network technologies. Annual report, March 7, 1996--February 28, 1997

    Energy Technology Data Exchange (ETDEWEB)

    Dershowitz, W.S.; La Pointe, P.R.; Einstein, H.H.; Ivanova, V.

    1998-01-01

    This report describes progress on the project, {open_quotes}Fractured Reservoir Discrete Feature Network Technologies{close_quotes} during the period March 7, 1996 to February 28, 1997. The report presents summaries of technology development for the following research areas: (1) development of hierarchical fracture models, (2) fractured reservoir compartmentalization and tributary volume, (3) fractured reservoir data analysis, and (4) integration of fractured reservoir data and production technologies. In addition, the report provides information on project status, publications submitted, data collection activities, and technology transfer through the world wide web (WWW). Research on hierarchical fracture models included geological, mathematical, and computer code development. The project built a foundation of quantitative, geological and geometrical information about the regional geology of the Permian Basin, including detailed information on the lithology, stratigraphy, and fracturing of Permian rocks in the project study area (Tracts 17 and 49 in the Yates field). Based on the accumulated knowledge of regional and local geology, project team members started the interpretation of fracture genesis mechanisms and the conceptual modeling of the fracture system in the study area. Research on fractured reservoir compartmentalization included basic research, technology development, and application of compartmentalized reservoir analyses for the project study site. Procedures were developed to analyze compartmentalization, tributary drainage volume, and reservoir matrix block size. These algorithms were implemented as a Windows 95 compartmentalization code, FraCluster.

  20. Finite volume hydromechanical simulation in porous media.

    Science.gov (United States)

    Nordbotten, Jan Martin

    2014-05-01

    Cell-centered finite volume methods are prevailing in numerical simulation of flow in porous media. However, due to the lack of cell-centered finite volume methods for mechanics, coupled flow and deformation is usually treated either by coupled finite-volume-finite element discretizations, or within a finite element setting. The former approach is unfavorable as it introduces two separate grid structures, while the latter approach loses the advantages of finite volume methods for the flow equation. Recently, we proposed a cell-centered finite volume method for elasticity. Herein, we explore the applicability of this novel method to provide a compatible finite volume discretization for coupled hydromechanic flows in porous media. We detail in particular the issue of coupling terms, and show how this is naturally handled. Furthermore, we observe how the cell-centered finite volume framework naturally allows for modeling fractured and fracturing porous media through internal boundary conditions. We support the discussion with a set of numerical examples: the convergence properties of the coupled scheme are first investigated; second, we illustrate the practical applicability of the method both for fractured and heterogeneous media.

  1. Numerical Investigation into the Effect of Natural Fracture Density on Hydraulic Fracture Network Propagation

    Directory of Open Access Journals (Sweden)

    Zhaohui Chong

    2017-07-01

    Full Text Available Hydraulic fracturing is an important method to enhance permeability in oil and gas exploitation projects and weaken hard roofs of coal seams to reduce dynamic disasters, for example, rock burst. It is necessary to fully understand the mechanism of the initiation, propagation, and coalescence of hydraulic fracture network (HFN caused by fluid flow in rock formations. In this study, a coupled hydro-mechanical model was built based on synthetic rock mass (SRM method to investigate the effects of natural fracture (NF density on HFN propagation. Firstly, the geometrical structures of NF obtained from borehole images at the field scale were applied to the model. Secondly, the micro-parameters of the proposed model were validated against the interaction between NF and hydraulic fracture (HF in physical experiments. Finally, a series of numerical simulations were performed to study the mechanism of HFN propagation. In addition, confining pressure ratio (CPR and injection rate were also taken into consideration. The results suggested that the increase of NF density drives the growth of stimulated reservoir volume (SRV, concentration area of injection pressure (CAIP, and the number of cracks caused by NF. The number of tensile cracks caused by rock matrix decrease gradually with the increase of NF density, and the number of shear cracks caused by rock matrix are almost immune to the change of NF density. The propagation orientation of HFN and the breakdown pressure in rock formations are mainly controlled by CPR. Different injection rates would result in a relatively big difference in the gradient of injection pressure, but this difference would be gradually narrowed with the increase of NF density. Natural fracture density is the key factor that influences the percentages of different crack types in HFN, regardless of the value of CPR and injection rate. The proposed model may help predict HFN propagation and optimize fracturing treatment designs in

  2. Percutaneous osteosynthesis of Galeazzi fracture-dislocation.

    Science.gov (United States)

    Gadegone, Wasudeo M; Salphale, Yogesh; Magarkar, Ds

    2010-10-01

    A Galeazzi fracture is defined as a fracture of the radius associated with dislocation of the distal radio-ulnar joint (DRUJ). The conventional surgical technique of nailing does not give enough stability and open reduction, internal fixation with the plate is associated with numerous complications. The stacked nailing for the management of these injuries provides adequate stability, maintains the relationship of the DRUJ and promotes uneventful union by closed technique. The purpose of this study is to evaluate the results of simple, user-friendly, low cost elastic stacked nailing for the management of Galeazzi fracture dislocation. We treated 22 young adults with fresh Galeazzi fracture-dislocation of the forearm, from January 2004 to January 2008, by percutaneous fixation of fracture by stacked elastic nailing at our institute. There were 19 males and three females and the age group ranged from 20-56 years (average 35 years). Surgery was performed within 48 to 72 hours under the guidance of image intensifier. Medullary cavity was filled with two elastic titanium nails having unequal lengths and diameter. One nail acts as a reduction nail and the other acts as a stabilizing nail. The results were evaluated using Mikic criteria based on union, alignment, relationship of the DRUJ, and movements at the inferior radio ulnar joint, elbow and wrist. In six cases, following radiological union, nails in the radius were extracted between six to nine months after operation because of discomfort complained by the patient at site of insertion. After one year follow-up, 18 patients had excellent, four had fair results. Closed reduction and internal fixation of Galeazzi fracture by two elastic rods re-establishes the normal relationship of the fractured fragments and the DRUJ without repair of the ligaments. The stability is achieved by the flexibility and elasticity of the nails, crowding of the medullary canal and anchorage they gain in the radial diaphysis. Elastic nailing

  3. Permeability Description by Characteristic Length, Tortuosity, Constriction and Porosity

    CERN Document Server

    Berg, Carl Fredrik

    2015-01-01

    In this article we investigate the permeability of a porous medium as given in Darcy's law. The permeability is described by an effective hydraulic pore radius in the porous medium, the fluctuation in local hydraulic pore radii, the length of streamlines, and the fractional volume conducting flow. The effective hydraulic pore radius is related to a characteristic hydraulic length, the fluctuation in local hydraulic radii is related to a constriction factor, the length of streamlines is characterized by a tortuosity, and the fractional volume conducting flow from inlet to outlet is described by an effective porosity. The characteristic length, the constriction factor, the tortuosity and the effective porosity are thus intrinsic descriptors of the pore structure relative to direction. We show that the combined effect of our pore structure description fully describes the permeability of a porous medium. The theory is applied to idealized porous media, where it reproduces Darcy's law for fluid flow derived from t...

  4. High Resolution Geophysical Characterization of Fractures within a Granitic Pluton

    Science.gov (United States)

    Pérez-Estaún, A.; Carbonell, R.

    2007-12-01

    The FEBEX underground gallery was excavated in the Aar Granite (Switzerland), a heterogeneous granite containing from very leucocratic facies to granodiorites. The geology of the gallery shows the existence of various sets of fractures with different attributes: geometry, kinematics, fracture infilling, etc. The study of the structural data, new observations on the FEBEX gallery itself and borehole televiewer data acquired in the newly drilled boreholes, have allowed to identify four sets of fractures. The first group of fractures has a typical distribution and characteristics of en echelon tension fractures and were formed in late magmatic stages, according with the paragenesis of the minerals that filled the craks. The main strike is around 300 (280-300). These fractures are deformed and displaced by the other group of faults. The second group corresponds to the lamprophyre dikes, of mantelic origin, with an orientation oblique to the tunnel, and slightly oblique to the first group of fractures (strike, 310-330). They were formed during an extension event well evidenced by their irregular margins and flame structures into the granite. The margins of these dikes show several reactivations as strike slip faults. Geophysical data has been acquired to characterized the fracture network of the surrounding volume within the FEBEX gallery. The geophysic data include new borehole logging such as Natural Gamma and Borehole Ground Penetrating radar. The processing and integration of these different data sets indicates that the GPR record can provide images of a third set of fractures, which are probably fluid filled. This set of fractures a subparallel to the tunnel axis and appear to intersect older boreholes which are nearly perpendicular to the axis of the FEBEX gallery.

  5. Characterizing Fracture Property Using Resistivity Measured at Different Frequencies

    Energy Technology Data Exchange (ETDEWEB)

    Horne, Roland N. [Stanford Univ., CA (United States); Li, Kewen [Stanford Univ., CA (United States)

    2014-09-30

    The objective was to develop geophysical approaches to detecting and evaluating the fractures created or existing in EGS and other geothermal reservoirs by measuring the resistivity at different frequencies. This project has been divided into two phases: Phase I (first year): Proof of Concept – develop the resistivity approach and verify the effect of frequency on the resistivity in rocks with artificial or natural fractures over a wide range of frequencies. Phase II: Prototyping Part 1 (second year): measure the resistivity in rocks with fractures of different apertures, different length, and different configurations at different frequencies. Part 2 (third year): develop mathematical models and the resistivity method; infer the fracture properties using the measured resistivity data.

  6. Fracture mechanics evaluation for at typical PWR primary coolant pipe

    Energy Technology Data Exchange (ETDEWEB)

    Tanaka, T. [Kansai Electric Power Company, Osaka (Japan); Shimizu, S.; Ogata, Y. [Mitsubishi Heavy Industries, Ltd., Kobe (Japan)

    1997-04-01

    For the primary coolant piping of PWRs in Japan, cast duplex stainless steel which is excellent in terms of strength, corrosion resistance, and weldability has conventionally been used. The cast duplex stainless steel contains the ferrite phase in the austenite matrix and thermal aging after long term service is known to change its material characteristics. It is considered appropriate to apply the methodology of elastic plastic fracture mechanics for an evaluation of the integrity of the primary coolant piping after thermal aging. Therefore we evaluated the integrity of the primary coolant piping for an initial PWR plant in Japan by means of elastic plastic fracture mechanics. The evaluation results show that the crack will not grow into an unstable fracture and the integrity of the piping will be secured, even when such through wall crack length is assumed to equal the fatigue crack growth length for a service period of up to 60 years.

  7. Fracture Assessment of Strengthened Cracked Metallic Components Using FRP Stiffeners

    Science.gov (United States)

    Ahmed, W. K.; Mourad, A.-H. I.

    2015-07-01

    The present study focuses on applying the fracture mechanics approach to the fracture assessment of a cracked member/component strengthened with fiber-reinforced polymer composite stiffeners. The parameters of linear elastic fracture mechanics (LEFM) — the stress intensity factor and the crack opening displacement — are estimated using a finite-element analysis. A metallic plate with an edge crack repaired with fiber-reinforced polymer composite stiffeners is considered in the study. The effects of crack length, debonding length, and adhesive stiffness on the LEFM parameters are examined. Two different loading conditions are considered — axial tension and bending. The results obtained show that fiber-reinforced polymer composite stiffeners are very useful in repairing cracked metallic components.

  8. Scaling exponents for fracture surfaces in opal glass

    Energy Technology Data Exchange (ETDEWEB)

    Chavez-Guerrero, L., E-mail: guerreroleo@hotmail.com [Facultad de Ingenieria Mecanica y Electrica. Cd. Universitaria s/n, C.P. 66450, Universidad Autonoma de Nuevo Leon, Nuevo Leon (Mexico); Center of Innovation, Research and Development on Engineering and Technology, Universidad Autonoma de Nuevo Leon Monterrey, C.P. 66600, Apodaca, Nuevo Leon (Mexico); Garza, F.J., E-mail: fjgarza@gama.fime.uanl.mx [Facultad de Ciencias Quimicas, Cd. Universitaria s/n, C.P. 66450, Universidad Autonoma de Nuevo Leon, Nuevo Leon (Mexico); Hinojosa, M., E-mail: hinojosa@gama.fime.uanl.mx [Facultad de Ingenieria Mecanica y Electrica. Cd. Universitaria s/n, C.P. 66450, Universidad Autonoma de Nuevo Leon, Nuevo Leon (Mexico); Center of Innovation, Research and Development on Engineering and Technology, Universidad Autonoma de Nuevo Leon Monterrey, C.P. 66600, Apodaca, Nuevo Leon (Mexico)

    2010-09-25

    We have investigated the scaling properties of fracture surfaces in opal glass. Specimens with two different opacifying particle sizes (1 {mu}m and 0.4 {mu}m) were broken by three-point bending test and the resulting fracture surfaces were analyzed using Atomic Force Microscopy. The analysis of the self-affine behavior was performed using the Variable Bandwidth and Height-Height Correlation Methods, and both the roughness exponent, {zeta}, and the correlation length, {xi}, were determined. It was found that the roughness exponent obtained in both samples is {zeta} {approx} 0.8; whereas the correlation length in both fractures is of the order of the particle size, demonstrating the dependence of this self-affine parameter on the microstructure of opal glass.

  9. Characterising rock fracture aperture-spacing relationships using power-law relationships: some considerations

    Science.gov (United States)

    Brook, Martin; Hebblewhite, Bruce; Mitra, Rudrajit

    2016-04-01

    The size-scaling of rock fractures is a well-studied problem in geology, especially for permeability quantification. The intensity of fractures may control the economic exploitation of fractured reservoirs because fracture intensity describes the abundance of fractures potentially available for fluid flow. Moreover, in geotechnical engineering, fractures are important for parameterisation of stress models and excavation design. As fracture data is often collected from widely-spaced boreholes where core recovery is often incomplete, accurate interpretation and representation of fracture aperture-frequency relationships from sparse datasets is important. Fracture intensity is the number of fractures encountered per unit length along a sample scanline oriented perpendicular to the fractures in a set. Cumulative frequency of fractures (F) is commonly related to fracture aperture (A) in the form of a power-law (F = aA-b), with variations in the size of the a coefficient between sites interpreted to equate to fracture frequency for a given aperture (A). However, a common flaw in this approach is that even a small change in b can have a large effect on the response of the fracture frequency (F) parameter. We compare fracture data from the Late Permian Rangal Coal Measures from Australia's Bowen Basin, with fracture data from Jurassic carbonates from the Sierra Madre Oriental, northeastern Mexico. Both power-law coefficient a and exponent b control the fracture aperture-frequency relationship in conjunction with each other; that is, power-laws with relatively low a coefficients have relatively high b exponents and vice versa. Hence, any comparison of different power-laws must take both a and b into consideration. The corollary is that different sedimentary beds in the Sierra Madre carbonates do not show ˜8× the fracture frequency for a given fracture aperture, as based solely on the comparison of coefficient a. Rather, power-law "sensitivity factors" developed from both

  10. On mechanics and material length scales of failure in heterogeneous interfaces using a finite strain high performance solver

    Science.gov (United States)

    Mosby, Matthew; Matouš, Karel

    2015-12-01

    Three-dimensional simulations capable of resolving the large range of spatial scales, from the failure-zone thickness up to the size of the representative unit cell, in damage mechanics problems of particle reinforced adhesives are presented. We show that resolving this wide range of scales in complex three-dimensional heterogeneous morphologies is essential in order to apprehend fracture characteristics, such as strength, fracture toughness and shape of the softening profile. Moreover, we show that computations that resolve essential physical length scales capture the particle size-effect in fracture toughness, for example. In the vein of image-based computational materials science, we construct statistically optimal unit cells containing hundreds to thousands of particles. We show that these statistically representative unit cells are capable of capturing the first- and second-order probability functions of a given data-source with better accuracy than traditional inclusion packing techniques. In order to accomplish these large computations, we use a parallel multiscale cohesive formulation and extend it to finite strains including damage mechanics. The high-performance parallel computational framework is executed on up to 1024 processing cores. A mesh convergence and a representative unit cell study are performed. Quantifying the complex damage patterns in simulations consisting of tens of millions of computational cells and millions of highly nonlinear equations requires data-mining the parallel simulations, and we propose two damage metrics to quantify the damage patterns. A detailed study of volume fraction and filler size on the macroscopic traction-separation response of heterogeneous adhesives is presented.

  11. Understanding hydraulic fracturing: a multi-scale problem.

    Science.gov (United States)

    Hyman, J D; Jiménez-Martínez, J; Viswanathan, H S; Carey, J W; Porter, M L; Rougier, E; Karra, S; Kang, Q; Frash, L; Chen, L; Lei, Z; O'Malley, D; Makedonska, N

    2016-10-13

    Despite the impact that hydraulic fracturing has had on the energy sector, the physical mechanisms that control its efficiency and environmental impacts remain poorly understood in part because the length scales involved range from nanometres to kilometres. We characterize flow and transport in shale formations across and between these scales using integrated computational, theoretical and experimental efforts/methods. At the field scale, we use discrete fracture network modelling to simulate production of a hydraulically fractured well from a fracture network that is based on the site characterization of a shale gas reservoir. At the core scale, we use triaxial fracture experiments and a finite-discrete element model to study dynamic fracture/crack propagation in low permeability shale. We use lattice Boltzmann pore-scale simulations and microfluidic experiments in both synthetic and shale rock micromodels to study pore-scale flow and transport phenomena, including multi-phase flow and fluids mixing. A mechanistic description and integration of these multiple scales is required for accurate predictions of production and the eventual optimization of hydrocarbon extraction from unconventional reservoirs. Finally, we discuss the potential of CO2 as an alternative working fluid, both in fracturing and re-stimulating activities, beyond its environmental advantages.This article is part of the themed issue 'Energy and the subsurface'.

  12. Reconstruction plate fixation of subtrochanteric femoral fractures in children.

    Science.gov (United States)

    El-Sayed, Moustafa; Abulsaad, Mazen; El-Hadidi, Mahmoud; El-Adl, Wael; El-Batouty, Magdy

    2007-08-01

    Pediatric subtrochanteric femoral fractures are rare and have received limited attention in the literature Treatment is controversial. Different treatment options are used: skin traction, 90/90 skeletal traction, spica casting, cast bracing, internal fixation and external fixation. The aim of this study is to present our results with internal fixation of subtrochanteric femoral fractures in children using a reconstruction plate. Between 2000 and 2004, eighteen patients with closed subtrochanteric femoral fractures were treated in the Mansoura Emergency Hospital. The average age at the time of injury was 8.2 years (range 5.3 years to 11.5 years). Pathological fractures and fractures associated with neuromuscular diseases were excluded from this study. Eight patients had head injuries and/or multiple injuries. In all cases a single 4.5 mm contoured reconstruction plate was used and a 6.5 mm cancellous screw was inserted through the plate into the femoral neck. Average follow-up was 38 months (range, 12 to 47 months). All fractures united with anatomical alignment within an average of 8 weeks (range 6 to 12 weeks). There were no deep infections and no significant limb length discrepancies. At the latest follow-up, no patient had any restriction of activities. Internal fixation with a reconstruction plate appears as a good treatment option for children with subtrochanteric femoral fractures.

  13. Stress generation and hierarchical fracturing in reactive systems

    Science.gov (United States)

    Jamtveit, B.; Iyer, K.; Royne, A.; Malthe-Sorenssen, A.; Mathiesen, J.; Feder, J.

    2007-12-01

    Hierarchical fracture patterns are the result of a slowly driven fracturing process that successively divides the rocks into smaller domains. In quasi-2D systems, such fracture patterns are characterized by four sided domains, and T-junctions where new fractures stop at right angles to pre-existing fractures. We describe fracturing of mm to dm thick enstatite layers in a dunite matrix from the Leka ophiolite complex in Norway. The fracturing process is driven by expansion of the dunite matrix during serpentinization. The cumulative distributions of fracture lengths show a scaling behavior that lies between a log - normal and power law (fractal) distribution. This is consistent with a simple fragmentation model in which domains are divided according to a 'top hat' distribution of new fracture positions within unfractured domains. Reaction-assisted hierarchical fracturing is also likely to be responsible for other (3-D) structures commonly observed in serpentinized ultramafic rocks, including the mesh-textures observed in individual olivine grains, and the high abundance of rectangular domains at a wide range of scales. Spectacular examples of 3-D hierarchical fracture patterns also form during the weathering of basaltic intrusions (dolerites). Incipient chemical weathering of dolerites in the Karoo Basin in South Africa occurs around water- filled fractures, originally produced by thermal contraction or by externally imposed stresses. This chemical weathering causes local expansion of the rock matrix and generates elastic stresses. On a mm to cm scale, these stresses lead to mechanical layer-by-layer spalling, producing the characteristic spheroidal weathering patterns. However, our field observations and computer simulations demonstrate that in confined environments, the spalling process alone is unable to relieve the elastic stresses. In such cases, chemical weathering drives a much larger scale hierarchical fracturing process in which fresh dolerite undergoes a

  14. Acute cognitive dysfunction after hip fracture

    DEFF Research Database (Denmark)

    Bitsch, M S; Foss, N B; Kristensen, B B;

    2006-01-01

    BACKGROUND: Patients undergoing hip fracture surgery often experience acute post-operative cognitive dysfunction (APOCD). The pathogenesis of APOCD is probably multifactorial, and no single intervention has been successful in its prevention. No studies have investigated the incidence of APOCD after......, fourth and seventh post-operative days with the Mini Mental State Examination (MMSE) score. RESULTS: Thirty-two per cent of patients developed a significant post-operative cognitive decline, which was associated with several pre-fracture patient characteristics, including age and cognitive function......, but also the number of peri-operative transfusions. The development of APOCD was also associated with impaired post-operative rehabilitation and an increased length of stay. APOCD was associated with the development of a major medical complication in 35% of all patients. In 65% of patients developing APOCD...

  15. Multicenter follow-up study of ankle fracture surgery

    Institute of Scientific and Technical Information of China (English)

    XU Hai-lin; WANG Gang; WANG Guang-lin; WU Xin-bao; LIU Li-min; LI Xuan; ZHANG Dian-ying; FU Zhong-guo; WANG Tian-bing; ZHANG Pei-xun; JIANG Bao-guo; SHEN Hui-liang

    2012-01-01

    Background Few data on ankle fractures in China from large multicenter epidemiological and clinical studies are available.The aim of this research was to evaluate the epidemiological features and surgical outcomes of ankle fractures by reviewing 235 patients who underwent ankle fracture surgery at five hospitals in China.Methods This study included patients who underwent ankle fracture surgery at five Chinese hospitals from January 2000 to July 2009.Age,gender,mechanism of injury,Arbeitsgemeinschaft für Osteosynthesefragen (AO) fracture type,fracture pattern,length of hospital stay and treatment outcome were recorded.Statistical analyses were conducted using SPSS software.The American Orthopedic Foot and Ankle Society (AOFAS) ankle-hindfoot scale,visual analogue scale (VAS),and arthritis scale were used to evaluate outcome.Results Of 235 patients with ankle fractures,105 were male with an average age of 37.8 years and 130 were female with an average age of 47.3 years.The average follow-up period was 55.7 months.There were significant differences in the ratios of patients in different age groups between males and females,and in mechanisms of injury among different age groups.There were also significant differences in the length of hospital stay among different fracture types and mechanisms of injury.In healed fractures,the average AOFAS ankle-hindfoot score was 95.5,with an excellence rate of 99.6%,the average VAS score was 0.17,and the average arthritis score was 0.18.Movement of the injured ankle was significantly different to that of the uninjured ankle.There were no significant differences between AO fracture types,fracture patterns or follow-up periods and AOFAS score,but there were some significant differences between these parameters and ankle joint movements,pain VAS score and arthritis score.Conclusions Ankle fractures occur most commonly in middle-aged and young males aged 20-39 years and in elderly females aged 50-69 years.The most common mechanisms of

  16. Mechanical transport in two-dimensional networks of fractures

    Energy Technology Data Exchange (ETDEWEB)

    Endo, H.K.

    1984-04-01

    The objectives of this research are to evaluate directional mechanical transport parameters for anisotropic fracture systems, and to determine if fracture systems behave like equivalent porous media. The tracer experiments used to measure directional tortuosity, longitudinal geometric dispersivity, and hydraulic effective porosity are conducted with a uniform flow field and measurements are made from the fluid flowing within a test section where linear length of travel is constant. Since fluid flow and mechanical transport are coupled processes, the directional variations of specific discharge and hydraulic effective porosity are measured in regions with constant hydraulic gradients to evaluate porous medium equivalence for the two processes, respectively. If the fracture region behaves like an equivalent porous medium, the system has the following stable properties: (1) specific discharge is uniform in any direction and can be predicted from a permeability tensor; and (2) hydraulic effective porosity is directionally stable. Fracture systems with two parallel sets of continuous fractures satisfy criterion 1. However, in these systems hydraulic effective porosity is directionally dependent, and thus, criterion 2 is violated. Thus, for some fracture systems, fluid flow can be predicted using porous media assumptions, but it may not be possible to predict transport using porous media assumptions. Two discontinuous fracture systems were studied which satisfied both criteria. Hydraulic effective porosity for both systems has a value between rock effective porosity and total porosity. A length-density analysis (LDS) of Canadian fracture data shows that porous media equivalence for fluid flow and transport is likely when systems have narrow aperture distributions. 54 references, 90 figures, 7 tables.

  17. Interfacial Fracture of Nanowire Electrodes of Lithium-Ion Batteries

    Science.gov (United States)

    Hardin, G. R.; Zhang, Y.; Fincher, C. D.; Pharr, M.

    2017-06-01

    Nanowires (NW) have emerged as a promising design for high power-density lithium-ion battery (LIB) electrodes. However, volume changes during cycling can lead to fracture of the NWs. In this paper, we investigate a particularly detrimental form of fracture: interfacial detachment of the NW from the current collector (CC). We perform finite element simulations to calculate the energy release rates of NWs during lithiation as a function of geometric parameters and mechanical properties. The simulations show that the energy release rate of a surface crack decreases as it propagates along the NW/CC interface toward the center of the NW. Moreover, this paper demonstrates that plastic deformation in the NWs drastically reduces stresses and thus crack-driving forces, thereby mitigating interfacial fracture. Overall, the results in this paper provide design guidelines for averting NW/CC interfacial fractures during operation of LIBs.

  18. Interfacial Fracture of Nanowire Electrodes of Lithium-Ion Batteries

    Science.gov (United States)

    Hardin, G. R.; Zhang, Y.; Fincher, C. D.; Pharr, M.

    2017-09-01

    Nanowires (NW) have emerged as a promising design for high power-density lithium-ion battery (LIB) electrodes. However, volume changes during cycling can lead to fracture of the NWs. In this paper, we investigate a particularly detrimental form of fracture: interfacial detachment of the NW from the current collector (CC). We perform finite element simulations to calculate the energy release rates of NWs during lithiation as a function of geometric parameters and mechanical properties. The simulations show that the energy release rate of a surface crack decreases as it propagates along the NW/CC interface toward the center of the NW. Moreover, this paper demonstrates that plastic deformation in the NWs drastically reduces stresses and thus crack-driving forces, thereby mitigating interfacial fracture. Overall, the results in this paper provide design guidelines for averting NW/CC interfacial fractures during operation of LIBs.

  19. Composite interlaminar fracture toughness: Three-dimensional finite element modeling for mixed mode 1, 2 and 3 fracture

    Science.gov (United States)

    Murthy, P. L. N.; Chamis, C. C.

    1986-01-01

    A computational method/procedure is described which can be used to simulate individual and mixed mode interlaminar fracture progression in fiber composite laminates. Different combinations of Modes 1, 2, and 3 fracture are simulated by varying the crack location through the specimen thickness and by selecting appropriate unsymmetric laminate configurations. The contribution of each fracture mode to strain energy release rate is determined by the local crack closure methods while the mixed mode is determined by global variables. The strain energy release rates are plotted versus extending crack length, where slow crack growth, stable crack growth, and rapid crack growth regions are easily identified. Graphical results are presented to illustrate the effectiveness and versatility of the computational simulation for: (1) evaluating mixed-mode interlaminar fracture, (2) for identifying respective dominant parameters, and (3) for selecting possible simple test methods.

  20. Composite interlaminar fracture toughness - Three-dimensional finite-element modeling for mixed mode I, II, and fracture

    Science.gov (United States)

    Murthy, Pappu L. N.; Chamis, Christos C.

    1988-01-01

    A computational method/procedure is described which can be used to simulate individual and mixed mode interlaminar fracture progression in fiber composite laminates. Different combinations of Modes 1, 2, and 3 fracture are simulated by varying the crack location through the specimen thickness and by selecting appropriate unsymmetric laminate configurations. The contribution of each fracture mode to strain energy release rate is determined by the local crack closure methods while the mixed mode is determined by global variables. The strain energy release rates are plotted versus extending crack length, where slow crack growth, stable crack growth, and rapid crack growth regions are easily identified. Graphical results are presented to illustrate the effectiveness and versatility of the computational simulation for: (1) evaluating mixed-mode interlaminar fracture, (2) for identifying respective dominant parameters, and (3) for selecting possible simple test methods.

  1. The effect of loading rate on ductile fracture toughness and fracture surface roughness

    Science.gov (United States)

    Osovski, S.; Srivastava, A.; Ponson, L.; Bouchaud, E.; Tvergaard, V.; Ravi-Chandar, K.; Needleman, A.

    2015-03-01

    The variation of ductile crack growth resistance and fracture surface roughness with loading rate is modeled under mode I plane strain, small scale yielding conditions. Three-dimensional calculations are carried out using an elastic-viscoplastic constitutive relation for a progressively cavitating solid with two populations of void nucleating second phase particles. Larger inclusions that result in void nucleation at an early stage are modeled as discrete void nucleation sites while smaller particles that require large strains to nucleate voids are homogeneously distributed. The calculations are carried out for two values of density of the larger inclusions, 3.6% and 7.1%, and for prescribed loading rates K˙˙I ranging from 1 ×105 MPa√{ m }s-1 to 5 ×107 MPa√{ m }s-1. The ductile fracture mode is found to undergo a transition from one that can be regarded as growth of a dominant main crack at the lower loading rates to one dominated by damage nucleation and micro-cracking ahead of the main crack at the higher loading rates. The values of JIC, the tearing modulus, TR, the total plastic dissipation and the plastic dissipation in the fracture process region are all found to increase with increasing loading rate. However, the ratio of plastic dissipation in the fracture process region to total plastic dissipation decreases with increasing prescribed loading rate. The fracture surfaces are found to display two self-affine regimes, with a Hurst exponent β ≈ 0.60 at small length scales and with β ≈ 0.45 at larger length scales. The multi-fractal spectra indicate multi-affine behavior in most cases but a range of loading rates and length scales exhibiting mono-affine behavior is also found. Parameters characterizing the fracture surface statistics, including the length scale at which a transition from a power law tail to an exponential tail occurs, are related to the mode of crack growth/damage accumulation. A linear relation is found between the values of JIC

  2. The Clinical Effect of the Length of the Rod under Direct Vision Combined with Posterior Reduction and Internal Fixation with Pulling Nerve Injury with Severe Traumatic Lumbar Fracture and Dislocation%后路直视下长短棒结合提拉复位内固定治疗伴神经损伤的重度创伤性腰椎骨折脱位的临床效果观察

    Institute of Scientific and Technical Information of China (English)

    孙中政; 孙海燕; 楚超; 孙树发; 丁超; 王英胜; 郝其全

    2015-01-01

    目的:观察直视下长短棒结合提拉复位内固定治疗伴神经损伤的重度创伤性腰椎骨折脱位在临床上的应用价值。方法回顾分析2010年~2013年解放军第89医院收治的35例伴神经损伤的重度腰椎骨折脱位采用后路直视下长短棒结合提拉复位内固定术,术后采用Suk标准判断植骨融合情况。结果平均手术时间约170min,出血量约600ml,术后随访脊柱植骨融合且稳定,术中未发现神经根及硬膜囊等医源性损伤。术后行脊柱正侧位X线检查,椎体脱位及旋转、成角移位均完全纠正,椎体前缘高度由术前的45%恢复到术后的95%.Cobb角从术前的32.5°±2.9°恢复至术后平均4.5°±2.2°。脊髓神经功能恢复按照Frankel截瘫分级,其中25例分别提高1~3级,10例A级无明显变化,术后3个月下地或坐轮椅,无迟发性脊髓损伤,未见断钉。结论重度骨折脱位伴神经损伤采用后路直视下长短棒结合提拉复位内固定术,可有效去除对神经的骨性压迫并重建脊柱的稳定性,融合率较高,安全有效。%[ ABSTRACT] Objective To observe the clinical application value of direct vision combined with the length of the rod pulling fixa -tion on lumbar fracture and dislocation with severe traumatic nerve injury .Methods Retrospective analysis of 35 cases of severe lumbar frac-ture and dislocation complicated with nerve injury in PLA 89th hospitals during 2010~2013 treated by pulling open reduction and internal fixation with posterior length under rod was made ,the treatment effect was evaluated by Suk standards .Results The average operation time ws about 170 minutes,blood loss was about 600ml,intraoperative nerve root and dural sac such as iatrogenic injury was not found and postop -erative follow-up showed stable spinal bone graft fusion .Postoperative lateral X -ray examination of the spine ,vertebrae dislocation and rota

  3. Three-Dimensional poroelastic effects during hydraulic fracturing in permeable rocks

    DEFF Research Database (Denmark)

    Salimzadeh, Saeed; Paluszny, Adriana; Zimmerman, Robert W.

    2017-01-01

    -dominated, and leakoff-dominated regimes. However, for intermediate regimes, these analytical solutions cannot be used to predict the key hydraulic fracturing variables, i.e. injection pressure, fracture aperture, and length. For leakoff-dominated cases in permeable rocks, the asymptotic solutions fail to accurately...... predict the lower-bound for fracture radius and apertures, and the upper-bound for fracture pressure. This is due to the poroelastic effects in the dilated rock matrix, as well as due to the multi-dimensional flow within matrix, which in many simulation codes is idealised as being one-dimensional, normal...

  4. FETAL FOOT LENGTH AND HAND LENGTH: RELATIONSHIP WITH CROWN RUMP LENGTH AND GESTATIONAL AGE

    Directory of Open Access Journals (Sweden)

    Garima

    2015-12-01

    Full Text Available BACKGROUND Estimation of gestational age of fetus is of great medicolegal importance. Multiple parameters of the fetal anatomical measurements are in use. However, gestational age assessment may be difficult in fetus with anencephaly, hydrocephalus, short limb dysplasia, post mortem destruction or in mutilated case. Study of literature suggests that fetal foot has a characteristic pattern of normal growth and the fetal foot shows gradual increase in length relative to the length of the embryo and could be used to estimate gestational age. The purpose of the present study is to determine the accuracy in estimating gestational age using fetal foot and hand length by studying its relation with crown rump length in the foetuses of Manipuri origin. AIMS AND OBJECTIVES 1 To study the relationship between fetal crown rump length and fetal hand and foot length, thereby determining the accuracy in estimating gestational age by a cross-sectional study. MATERIALS AND METHODS A total of 100 formalin fixed fetuses of Manipuri origin, obtained from the Department of Obstetrics and Gynaecology, Regional Institute of Medical Sciences, Imphal, were included in the study, carried out in the Department of Anatomy, from February 2015 to July 2015. The parameters studied were crown rump length, foot length and hand length of fetuses. The data was analysed using SPSS software by regression analysis. Graphs were also plotted to determine pattern of growth and their correlation with crown rump length if any. RESULTS A total of 100 fetuses were studied, of which 43 were females and 57 were males. The mean foot length and hand length progressively increased with increase in crown rump length. Measurements were not significantly different in right or left side or among male and female fetuses. A statistically significant linear relationship was seen between foot length and crown rump length of the fetus (r=0.980, p<0.0001 and hand length and crown rump length of the fetus

  5. Fluid trapping during capillary displacement in fractures

    Science.gov (United States)

    Yang, Zhibing; Neuweiler, Insa; Méheust, Yves; Fagerlund, Fritjof; Niemi, Auli

    2016-09-01

    The spatial distribution of fluid phases and the geometry of fluid-fluid interfaces resulting from immiscible displacement in fractures cast decisive influence on a range of macroscopic flow parameters. Most importantly, these are the relative permeabilities of the fluids as well as the macroscopic irreducible saturations. They also influence parameters for component (solute) transport, as it usually occurs through one of the fluid phase only. Here, we present a numerical investigation on the critical role of aperture variation and spatial correlation on fluid trapping and the morphology of fluid phase distributions in a geological fracture. We consider drainage in the capillary dominated regime. The correlation scale, that is, the scale over which the two facing fracture walls are matched, varies among the investigated geometries between L/256 and L (self-affine fields), L being the domain/fracture length. The aperture variability is quantified by the coefficient of variation (δ), ranging among the various geometries from 0.05 to 0.25. We use an invasion percolation based model which has been shown to properly reproduce displacement patterns observed in previous experiments. We present a quantitative analysis of the size distribution of trapped fluid clusters. We show that when the in-plane curvature is considered, the amount of trapped fluid mass first increases with increasing correlation scale Lc and then decreases as Lc further increases from some intermediate scale towards the domain length scale L. The in-plane curvature contributes to smoothening the invasion front and to dampening the entrapment of fluid clusters of a certain size range that depends on the combination of random aperture standard deviation and spatial correlation.

  6. Extracting porosity and modelling permeability from μCT and FIB-SEM data of fractured dolomites from a hydrocarbon reservoir

    Science.gov (United States)

    Voorn, M. H.; Rath, A.; Exner, U.

    2012-04-01

    Currently oil and gas in the Vienna Basin are produced partly from the Upper Triassic Hauptdolomit formation. Various drill-cores were retrieved from densely fractured dolomites from depths between 3000 and 5300 m. Porosity and permeability assessment in specimen from such fractured rocks proves to be difficult by common laboratory methods, and also 2D sample analysis alone is insufficient to this end. In our study, X-ray micro-Computed Tomography (µCT) is used to visualise the inside of core samples of fractured Hauptdolomit. The biggest advantage of µCT is that it provides a 3D view of the fractures and other porosity, without destroying the sample. Core sample descriptions, 2D thin section analysis and standard laboratory measurements are used for extended analysis and cross-calibration of the results. In addition, 3D porosity visualisations at the micro- to nano-scale are obtained from Focussed Ion Beam - Scanning Electron Microscopy (FIB-SEM) on thin sections. The narrow fractures encountered in the Hauptdolomit samples require sufficient resolution µCT scans (i.e. better than ca. 25 µm). Full 10 cm diameter cores of sample prove to be too thick and dense, so that the fracture network cannot be recorded properly. 3 cm sized plugs on the other hand do provide workable results. After obtaining good datasets, the fractures need to be segmented (separated) from the full dataset for further analysis. A large amount of different segmentation routines is available from literature, but very little are applicable for segmenting narrow fractures, especially not in geological literature. Our current best results stem from applying the so-called "Frangi filter" used in segmentation routines in the medical sciences for segmenting blood vessels. After this segmentation, the fracture patterns can be extracted, and quantitative analysis of the bulk porosity and porosity distribution, fracture aperture and length can be performed. The data obtained by FIB-SEM is treated in

  7. CT classification of acetabular fractures

    Energy Technology Data Exchange (ETDEWEB)

    Marincek, B.; Porcellini, B.; Robotti, G.

    1984-05-01

    The contribution of computed tomography (CT) in classifying acetabular fractures was analysed retrospectively in 33 cases. CT and plain radiography classification agreed in 27 cases (82%). CT revealed more extensive fractures in 6 patients (thereof 5 patients with associated fractures). In 10 patients (thereof 9 patients with associated fractures) CT showed intraarticular fragments; radiographically intraarticular fragments were seen only in 2 patients and suspected in 4. CT is of considerable aid in defining the fracture pattern. It should be used mainly in patients with radiographically difficult interpretable associated fractures in order to assess preoperatively the weight-bearing part of the acetabulum, the degree of displacement and the presence of intraarticular fragments.

  8. Atomistic Simulations of Nanotube Fracture

    CERN Document Server

    Belytschko, T; Schatz, G; Ruoff, R S

    2002-01-01

    The fracture of carbon nanotubes is studied by atomistic simulations. The fracture behavior is found to be almost independent of the separation energy and to depend primarily on the inflection point in the interatomic potential. The rangle of fracture strians compares well with experimental results, but predicted range of fracture stresses is marketly higher than observed. Various plausible small-scale defects do not suffice to bring the failure stresses into agreement with available experimental results. As in the experiments, the fracture of carbon nanotubes is predicted to be brittle. The results show moderate dependence of fracture strength on chirality.

  9. Modelling length of hospital stay in motor victims

    Directory of Open Access Journals (Sweden)

    Mercedes Ayuso-Gutiérrez

    2015-03-01

    Full Text Available Objective. To analyze which socio-demographic and other factors related to motor injuries affect the length of hospital recovery stay. Materials and methods. In the study a sample of 17 932 motor accidents was used. All the crashes occurred in Spain between 2000 and 2007. Different regression models were fitted to data to identify and measure the impact of a set of explanatory regressors. Results. Time of hospital stay for men is on average 41% larger than for women. When the victim has a fracture as a consequence of the accident, the mean time of hospital stay is multiplied by five. Injuries located in lower extremities, the head and abdomen are associated with greater hospitalization lengths. Conclusions. Gender, age and type of victim, as well as the location and nature of injuries, are found to be factors that have significant impact on the expected length of hospital stay.

  10. Predicting bulk permeability using outcrop fracture attributes: The benefits of a Maximum Likelihood Estimator

    Science.gov (United States)

    Rizzo, R. E.; Healy, D.; De Siena, L.

    2015-12-01

    The success of any model prediction is largely dependent on the accuracy with which its parameters are known. In characterising fracture networks in naturally fractured rocks, the main issues are related with the difficulties in accurately up- and down-scaling the parameters governing the distribution of fracture attributes. Optimal characterisation and analysis of fracture attributes (fracture lengths, apertures, orientations and densities) represents a fundamental step which can aid the estimation of permeability and fluid flow, which are of primary importance in a number of contexts ranging from hydrocarbon production in fractured reservoirs and reservoir stimulation by hydrofracturing, to geothermal energy extraction and deeper Earth systems, such as earthquakes and ocean floor hydrothermal venting. This work focuses on linking fracture data collected directly from outcrops to permeability estimation and fracture network modelling. Outcrop studies can supplement the limited data inherent to natural fractured systems in the subsurface. The study area is a highly fractured upper Miocene biosiliceous mudstone formation cropping out along the coastline north of Santa Cruz (California, USA). These unique outcrops exposes a recently active bitumen-bearing formation representing a geological analogue of a fractured top seal. In order to validate field observations as useful analogues of subsurface reservoirs, we describe a methodology of statistical analysis for more accurate probability distribution of fracture attributes, using Maximum Likelihood Estimators. These procedures aim to understand whether the average permeability of a fracture network can be predicted reducing its uncertainties, and if outcrop measurements of fracture attributes can be used directly to generate statistically identical fracture network models.

  11. [Humeral shaft fractures].

    Science.gov (United States)

    Schittko, A

    2004-08-01

    Since Lorenz Böhler postulated in his 1964 summary with the title "Against the operative treatment of fresh humeral shaft fractures" that the operative treatment is the exception in the therapy of humeral fractures times have changed. In the last years a conservative treatment of a humeral fracture is the exception and only used after straight indications. The operative therapy nowadays is the gold standard because of the development of new intramedullar and rotation stable implants in addition to the classical osteosynthesis with the plate. But even the external fixator for primary stabilisation in polytrauma patients or as rescue procedure after complications should be in repertory of every orthopedic surgeon. Attention should be put on the avoidance of primary and the correct treatment of secondary nerval lesions, esp. of the radial nerve. Here we are tending to the operative revision of the nerve in indistinct cases. In the treatment of the seldom humeral shaft fracture of the child conservative treatment is to prefer; in complications a resolute shift to a final operative stabilisation of the fracture is necessary.

  12. Hydrogeological characterisation and modelling of deformation zones and fracture domains, Forsmark modelling stage 2.2

    Energy Technology Data Exchange (ETDEWEB)

    Follin, Sven (SF GeoLogic AB, Taeby (SE)); Leven, Jakob (Swedish Nuclear Fuel and Waste Management Co., Stockholm (SE)); Hartley, Lee; Jackson, Peter; Joyce, Steve; Roberts, David; Swift, Ben (Serco Assurance, Harwell (GB))

    2007-09-15

    The work reported here collates the structural-hydraulic information gathered in 21 cored boreholes and 32 percussion-drilled boreholes belonging to Forsmark site description, modelling stage 2.2. The analyses carried out provide the hydrogeological input descriptions of the bedrock in Forsmark needed by the end users Repository Engineering, Safety Assessment and Environmental Impact Assessment; that is, hydraulic properties of deformation zones and fracture domains. The same information is also needed for constructing 3D groundwater flow models of the Forsmark site and surrounding area. The analyses carried out render the following conceptual model regarding the observed heterogeneity in deformation zone transmissivity: We find the geological division of the deterministically modelled deformation zones into eight categories (sets) useful from a hydrogeological point of view. Seven of the eight categories are steeply dipping, WNW, NW, NNW, NNE, NE, ENE and EW, and on is gently dipping, G. All deformation zones, regardless of orientation (strike and dip), are subjected to a substantial decrease in transmissivity with depth. The data gathered suggest a contrast of c. 20,000 times for the uppermost one kilometre of bedrock, i.e. more than four orders of magnitude. The hydraulic properties below this depth are not investigated. The lateral heterogeneity is also substantial but more irregular in its appearance. For instance, for a given elevation and deformation zone category (orientation), the spatial variability in transmissivity within a particular deformation zone appears to be as large as the variability between all deformation zones. This suggests that the lateral correlation length is shorter than the shortest distance between two adjacent observation points and shorter than the category spacing. The observation that the mean transmissivity of the gently-dipping deformation zones is c. one to two orders of magnitude greater than the mean transmissivities of all

  13. The impact of different aperture distribution models and critical stress criteria on equivalent permeability in fractured rocks

    Science.gov (United States)

    Bisdom, Kevin; Bertotti, Giovanni; Nick, Hamidreza M.

    2016-05-01

    Predicting equivalent permeability in fractured reservoirs requires an understanding of the fracture network geometry and apertures. There are different methods for defining aperture, based on outcrop observations (power law scaling), fundamental mechanics (sublinear length-aperture scaling), and experiments (Barton-Bandis conductive shearing). Each method predicts heterogeneous apertures, even along single fractures (i.e., intrafracture variations), but most fractured reservoir models imply constant apertures for single fractures. We compare the relative differences in aperture and permeability predicted by three aperture methods, where permeability is modeled in explicit fracture networks with coupled fracture-matrix flow. Aperture varies along single fractures, and geomechanical relations are used to identify which fractures are critically stressed. The aperture models are applied to real-world large-scale fracture networks. (Sub)linear length scaling predicts the largest average aperture and equivalent permeability. Barton-Bandis aperture is smaller, predicting on average a sixfold increase compared to matrix permeability. Application of critical stress criteria results in a decrease in the fraction of open fractures. For the applied stress conditions, Coulomb predicts that 50% of the network is critically stressed, compared to 80% for Barton-Bandis peak shear. The impact of the fracture network on equivalent permeability depends on the matrix hydraulic properties, as in a low-permeable matrix, intrafracture connectivity, i.e., the opening along a single fracture, controls equivalent permeability, whereas for a more permeable matrix, absolute apertures have a larger impact. Quantification of fracture flow regimes using only the ratio of fracture versus matrix permeability is insufficient, as these regimes also depend on aperture variations within fractures.

  14. Fracture-Flow-Enhanced Solute Diffusion into Fractured Rock

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Yu-Shu; Ye, Ming; Sudicky, E.A.

    2007-12-15

    We propose a new conceptual model of fracture-flow-enhanced matrix diffusion, which correlates with fracture-flow velocity, i.e., matrix diffusion enhancement induced by rapid fluid flow within fractures. According to the boundary-layer or film theory, fracture flow enhanced matrix diffusion may dominate mass-transfer processes at fracture-matrix interfaces, because rapid flow along fractures results in large velocity and concentration gradients at and near fracture-matrix interfaces, enhancing matrix diffusion at matrix surfaces. In this paper, we present a new formulation of the conceptual model for enhanced fracture-matrix diffusion, and its implementation is discussed using existing analytical solutions and numerical models. In addition, we use the enhanced matrix diffusion concept to analyze laboratory experimental results from nonreactive and reactive tracer breakthrough tests, in an effort to validate the new conceptual model.

  15. IMPEDANCE OF FINITE LENGTH RESISTOR

    Energy Technology Data Exchange (ETDEWEB)

    KRINSKY, S.; PODOBEDOV, B.; GLUCKSTERN, R.L.

    2005-05-15

    We determine the impedance of a cylindrical metal tube (resistor) of radius a, length g, and conductivity {sigma}, attached at each end to perfect conductors of semi-infinite length. Our main interest is in the asymptotic behavior of the impedance at high frequency, k >> 1/a. In the equilibrium regime, , the impedance per unit length is accurately described by the well-known result for an infinite length tube with conductivity {sigma}. In the transient regime, ka{sup 2} >> g, we derive analytic expressions for the impedance and wakefield.

  16. Surgical Treatment of Orbital Blowout Fractures: Complications and Postoperative Care Patterns.

    Science.gov (United States)

    Shew, Matthew; Carlisle, Michael P; Lu, Guanning Nina; Humphrey, Clinton; Kriet, J David

    2016-11-01

    Orbital fractures are a common result of facial trauma. Sequelae and indications for repair include enophthalmos and/or diplopia from extraocular muscle entrapment. Alloplastic implant placement with careful release of periorbital fat and extraocular muscles can effectively restore extraocular movements, orbital integrity, and anatomic volume. However, rare but devastating complications such as retrobulbar hematoma (RBH) can occur after repair, which pose a risk of permanent vision loss if not addressed emergently. For this reason, some surgeons take the precaution of admitting patients for 24-hour postoperative vision checks, while others do not. The incidence of postoperative RBH has not been previously reported and existing data are limited to case reports. Our aim was to examine national trends in postoperative management and to report the incidence of immediate postoperative complications at our institution following orbital repair. A retrospective assessment of orbital blowout fractures was undertaken to assess immediate postoperative complications including RBH. Only patients treated by a senior surgeon in the Department of Otolaryngology were included in the review. In addition, we surveyed AO North America (AONA) Craniomaxillofacial faculty to assess current trends in postoperative management. There were 80 patients treated surgically for orbital blowout fractures over a 9.5-year period. Nearly all patients were observed overnight (74%) or longer (25%) due to other trauma. Average length of stay was 17 hours for those observed overnight. There was one (1.3%) patient with RBH, who was treated and recovered without sequelae. Results of the survey indicated that a majority (64%) of responders observe postoperative patients overnight. Twenty-nine percent of responders indicated that they send patients home the same day of surgery. Performance of more than 20 orbital repairs annually significantly increased the likelihood that faculty would manage patients on

  17. Thermal-Hydrologic-Mechanical Behavior of Single Fractures in EGS Reservoirs

    Science.gov (United States)

    Zyvoloski, G.; Kelkar, S.; Yoshioka, K.; Rapaka, S.

    2010-12-01

    Enhanced Geothermal Systems (EGS) rely on the creation a connected fracture system or the enhancement of existing (natural) fractures by hydraulic and chemical treatments. EGS studies at Fenton Hill (New Mexico, USA) and Hijiori (Japan) have revealed that only a limited number of fractures contribute to the effective heat transfer surface area. Thus, the economic viability of EGS depends strongly on the creation and spacing of single fractures in order to efficiently mine heat from given volume of rock. Though there are many similarities between EGS and natural geothermal reservoirs, a major difference between the reservoir types is the (typically) high pumping pressures and induced thermal stresses at the injection wells of an EGS reservoir. These factors can be responsible for fracture dilation/extension and thermal short circuiting and depend strongly on the surrounding state of stress in the reservoir and mechanical properties. We will present results from our study of the thermal-hydrologic-mechanical (THM) behavior of a single fracture in a realistic subsurface stress field. We will show that fracture orientation, the stress environment, fracture permeability structure, and the relationship between permeability changes in a fracture resulting from mechanical displacement are all important when designing and managing an EGS reservoir. Lastly, we present a sensitivity analysis of the important parameters that govern fracture behavior with respect to field measurements. Temperature in high permeability fracture in an EGS reservoir

  18. Analysis of microseismicity using fuzzy logic and fractals for fracture network characterization

    Science.gov (United States)

    Aminzadeh, F.; Ayatollahy Tafti, T.; Maity, D.; Boyle, K.; Sahimi, M.; Sammis, C. G.

    2010-12-01

    The area where microseismic events occur may be correlated with the fracture network at a geothermal field. For an Enhanced Geothermal System (EGS) reservoir, an extensive fracture network with a large aerial distribution is required. Pore-pressure increase, temperature changes, volume change due to fluid withdrawal/injection and chemical alteration of fracture surfaces are all mechanisms that may explain microseismic events at a geothermal field. If these mechanisms are operative, any fuzzy cluster of the microseismic events should represent a connected fracture network. Drilling new EGS wells (both injection and production wells) in these locations may facilitate the creation of an EGS reservoir. In this article we use the fuzzy clustering technique to find the location and characteristics of fracture networks in the Geysers geothermal field. We also show that the centers of these fuzzy clusters move in time, which may represent fracture propagation or fluid movement within the fracture network. Furthermore, analyzing the distribution of fuzzy hypocenters and quantifying their fractal structure helps us to develop an accurate fracture map for the reservoir. Combining the fuzzy clustering results with the fractal analysis allows us to better understand the mechanisms for fracture stimulation and better characterize the evolution of the fracture network. We also show how micro-earthquake date collected in different time periods can be correlated with drastic changes in the distribution of active fractures resulting from injection, production or other transient events.

  19. Clinical usefulness of CT in the diagnosis of severe pelvic fractures

    Energy Technology Data Exchange (ETDEWEB)

    Gotoh, Shinsuke; Tajima, Hiroyuki [Nippon Medical School, Tokyo (Japan)

    1998-11-01

    The purpose of this paper is to clarify the clinical significance of CT in the diagnosis of severe pelvic fractures. Fifty-six consecutive patients with severe pelvic ring fractures were the subjects of this study. The assessments were as follows: comparison of the diagnostic value of plain X-P and CT for the detection of pelvic fractures, comparison hemodynamic findings before TAE therapy, comparison between abnormal angiographic findings and fracture sites on CT, and comparison between abnormal angiographic findings and volume of retroperitoneal hematomas on CT. CT was more useful for the detection of severe pelvic ring fractures, especially for sacral fracture and iliosacral joint dislocations, than plain X-P. Sacral fracture group was more severe than iliac fracture group on CT. There was a discrepancy between the angiographic findings and fracture sites in 20 of the 56 patients. Angiographic abnormalities without fracture were seen especially in the lateral sacral artery and iliolumbar artery. There was a discrepancy between the angiographic findings and retroperitoneal hematomas in 38 of the 56 patients. Retroperitoneal hematomas, especially around the ilium, were seen on CT in 40 areas in the absence of any abnormal angiographic findings. Conversely, angiographic extravasation without hematoma on CT was seen in 20 areas, especially in lateral sacral artery. CT is useful for detection and intervention in severe pelvic ring fractures. (author)

  20. Effect of leptin on bone metabolism in rat model of traumatic brain injury and femoral fracture

    Institute of Scientific and Technical Information of China (English)

    WANG Lei; YUAN Ji-shan; ZHANG Hong-xi; DING Hua; TANG Xing-guo; WEI Yong-zhong

    2011-01-01

    Objective: To observe serum and callus leptin expression within the setting of fracture and traumatic brain injury (TBI).Methods: Atotal of 64 male SD rats were randomized equally into 4 groups: nonoperated group, TBI group, fraeture group, and fracture+TBI group. Rats were sacrificed at 2, 4, 8 and 12 weeks after fracture+TBI. Serum leptin was detected using radioimmunoassay, and callus formation was measured radiologically. Callus leptin was analyzed by immunohistochemistry.Results: Serum ieptin levels in the fracture group, TBI group and combined fracture+TBI group were all significantly increased compared with control group at the 2 week time-point (P<0.05). Serum leptin in the combined fracture +TBI group was significantly higher than that in the fracture and TBI groups at 4 and 8 weeks after injury (P<0. 05).The percentage of leptin-positive cells in the fracture+TBI callus and callus volume were significantly higher than those in the fracture-only group (P<0.01).Conclusions: We demonstrated elevated leptin expression within healing bone especially in the first 8 weeks in a rat model of fracture and TBI. A close association exists between leptin levels and the degree of callus formation in fractures.

  1. Molecular-dynamics Simulation-based Cohesive Zone Representation of Intergranular Fracture Processes in Aluminum

    Science.gov (United States)

    Yamakov, Vesselin I.; Saether, Erik; Phillips, Dawn R.; Glaessgen, Edward H.

    2006-01-01

    A traction-displacement relationship that may be embedded into a cohesive zone model for microscale problems of intergranular fracture is extracted from atomistic molecular-dynamics simulations. A molecular-dynamics model for crack propagation under steady-state conditions is developed to analyze intergranular fracture along a flat 99 [1 1 0] symmetric tilt grain boundary in aluminum. Under hydrostatic tensile load, the simulation reveals asymmetric crack propagation in the two opposite directions along the grain boundary. In one direction, the crack propagates in a brittle manner by cleavage with very little or no dislocation emission, and in the other direction, the propagation is ductile through the mechanism of deformation twinning. This behavior is consistent with the Rice criterion for cleavage vs. dislocation blunting transition at the crack tip. The preference for twinning to dislocation slip is in agreement with the predictions of the Tadmor and Hai criterion. A comparison with finite element calculations shows that while the stress field around the brittle crack tip follows the expected elastic solution for the given boundary conditions of the model, the stress field around the twinning crack tip has a strong plastic contribution. Through the definition of a Cohesive-Zone-Volume-Element an atomistic analog to a continuum cohesive zone model element - the results from the molecular-dynamics simulation are recast to obtain an average continuum traction-displacement relationship to represent cohesive zone interaction along a characteristic length of the grain boundary interface for the cases of ductile and brittle decohesion. Keywords: Crack-tip plasticity; Cohesive zone model; Grain boundary decohesion; Intergranular fracture; Molecular-dynamics simulation

  2. Polyketide chain length control by chain length factor.

    Science.gov (United States)

    Tang, Yi; Tsai, Shiou-Chuan; Khosla, Chaitan

    2003-10-22

    Bacterial aromatic polyketides are pharmacologically important natural products. A critical parameter that dictates product structure is the carbon chain length of the polyketide backbone. Systematic manipulation of polyketide chain length represents a major unmet challenge in natural product biosynthesis. Polyketide chain elongation is catalyzed by a heterodimeric ketosynthase. In contrast to homodimeric ketosynthases found in fatty acid synthases, the active site cysteine is absent from the one subunit of this heterodimer. The precise role of this catalytically silent subunit has been debated over the past decade. We demonstrate here that this subunit is the primary determinant of polyketide chain length, thereby validating its designation as chain length factor. Using structure-based mutagenesis, we identified key residues in the chain length factor that could be manipulated to convert an octaketide synthase into a decaketide synthase and vice versa. These results should lead to novel strategies for the engineered biosynthesis of hitherto unidentified polyketide scaffolds.

  3. Curve Length Estimation using Vertix Chain Code Curve Length Estimation

    Directory of Open Access Journals (Sweden)

    Habibollah Haron

    2010-09-01

    Full Text Available Most of the applications in image analysis are based on Freeman chain code. In this paper, for the first time, vertex chain code (VCC proposed by Bribiesca is applied to improve length estimation of the 2D digitized curve. The chain code has some preferences such as stable in shifting, turning, mirroring movement of image and has normalized starting point. Due to the variety of length estimator methods, we focused on the three specific techniques. First, the way Bribiesca proposed which is based on counting links between vertices; second, based on maximum length digital straight segments (DSSs and lastly local metrics. The results of these length estimators with the real perimeter are compared. Results thus obtained exhibits thatlength estimation using VCC is nearest to the actual length.

  4. Field-wide flow simulation in fractured porous media within lattice Boltzmann framework

    Science.gov (United States)

    Benamram, Z.; Tarakanov, A.; Nasrabadi, H.; Gildin, E.

    2016-10-01

    In this paper, a generalized lattice Boltzmann model for simulating fluid flow in porous media at the representative volume element scale is extended towards applications of hydraulically and naturally fractured reservoirs. The key element within the model is the development of boundary conditions for a vertical well and horizontal fracture with minimal node usage. In addition, the governing non-dimensional equations are derived and a new set of dimensionless numbers are presented for the simulation of a fractured reservoir system. Homogenous and heterogeneous vertical well and fracture systems are simulated and verified against commercial reservoir simulation suites. Results are in excellent agreement to analytical and finite difference solutions.

  5. Transstyloid, transscaphoid, transcapitate fracture: a variant of scaphocapitate fractures.

    LENUS (Irish Health Repository)

    Burke, Neil G

    2014-01-01

    Transstyloid, transscaphoid, transcapitate fractures are uncommon. We report the case of a 28-year-old man who sustained this fracture following direct trauma. The patient was successfully treated by open reduction internal fixation of the scaphoid and proximal capitate fragment, with a good clinical outcome at 1-year follow-up. This pattern is a new variant of scaphocapitate fracture as involves a fracture of the radial styloid as well.

  6. Vertebral Geometry Parameters Can Predict Fractures

    Directory of Open Access Journals (Sweden)

    P Tofighi

    2007-01-01

    Conclusion: Vertebral fractures are common fractures in postmenopausal women. There was a correlation between verte¬bral height and fractures. Vertebral geometric parameters especially height T score can be used for fracture screening.

  7. Galeazzi fractures and dislocations.

    Science.gov (United States)

    Giannoulis, Filippos S; Sotereanos, Dean G

    2007-05-01

    In 1934, fractures of the middle and distal third of the radius associated with instability of the distal radial ulnar joint (DRUJ) were described by Galeazzi. This type of lesion is characterized by its unstable nature and the need for open reduction and internal fixation to achieve a satisfactory functional outcome. A high index of suspicion should be maintained by the surgeon, and a thorough examination for instability of the DRUJ must be conducted. The marked instability of this fracture-dislocation complex is further enhanced by the disruption of the triangular fibrocartilage complex, either with or without ulna styloid fracture. Treatment in adults is surgical, and both bone and soft tissue injuries should be addressed.

  8. DEM Particle Fracture Model

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Boning [Univ. of Colorado, Boulder, CO (United States); Herbold, Eric B. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Homel, Michael A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Regueiro, Richard A. [Univ. of Colorado, Boulder, CO (United States)

    2015-12-01

    An adaptive particle fracture model in poly-ellipsoidal Discrete Element Method is developed. The poly-ellipsoidal particle will break into several sub-poly-ellipsoids by Hoek-Brown fracture criterion based on continuum stress and the maximum tensile stress in contacts.