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Sample records for bone elements excavated

  1. Discrete Element Modeling for Mobility and Excavation

    Science.gov (United States)

    Knuth, M. A.; Hopkins, M. A.

    2011-12-01

    The planning and completion of mobility and excavation efforts on the moon requires a thorough understanding of the planetary regolith. In this work, a discrete element method (DEM) model is created to replicate those activities in the laboratory and for planning mission activities in the future. The crux of this work is developing a particle bed that best replicates the regolith tool/wheel interaction seen in the laboratory. To do this, a DEM geotechnical triaxial strength cell was created allowing for comparison of laboratory JSC-1a triaxial tests to DEM simulated soils. This model relies on a triangular lattice membrane covered triaxial cell for determining the macroscopic properties of the modeled granular material as well as a fast and efficient contact detection algorithm for a variety of grain shapes. Multiple grain shapes with increasing complexity (ellipsoid, poly-ellipsoid and polyhedra) have been developed and tested. This comparison gives us a basis to begin scaling DEM grain size and shape to practical values for mobility and excavation modeling. Next steps include development of a DEM scoop for percussive excavation testing as well as continued analysis of rover wheel interactions using a wide assortment of grain shape and size distributions.

  2. Deformation Control of Deep Excavation Pit and Numerical Simulation with Finite Element Method

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The authors firstly introduce deformation control of deep excavation pit in detail, and then put forward new conceptions such as: effective coefficient of excavation pit, effective area, ineffective area and critical line, and also put forward the referential criteria of deformation control. The System of Optimization Design with Deformation Control of Deep Excavation Pit and Numerical Simulation with Finite Element Method (SDCDEFEM) is also briefly introduced. Factors influencing deformation of excavation pit are analyzed by the system. The measured and simulated data of maximum deformations (settlement, displacement and upheaval) and their positions are analyzed and discussed. The statistic formula estimating maximum deformations and their positions was gained, and economical-effective measures of deformation control were brought forward.

  3. Discrete element analysis of the excavation effect of cross-river tunnel on the surroundings

    Directory of Open Access Journals (Sweden)

    Liu Dongyuan

    2017-01-01

    Full Text Available Cross-river tunnel as one of the underground constructions is complicated during its construction. For stability of tunnel excavation, it is emergency to analyze the dynamic characteristics of tunnel deformation under high water pressure. Therefore, a cross-river tunnel model is proposed based on DEM in this paper. Stiffness of particles decreases during excavation process which is as one of excavation methods. Porosity ratio of original porosity over its value at different excavation time has been considered. Radial displacements of particles at different angle around the tunnel are detected during excavation process. It shows that large deformation occurs at the vault of the excavation zone which accompanies with large radial displacement. The upper half of the tunnel performs larger deformation than the lower half part which results in many cracks in the concrete lining, the high water pressure may play an crucial role in it.

  4. FREESURF: A three-dimensional finite-element model for simulating groundwater flow into and around an excavation

    Energy Technology Data Exchange (ETDEWEB)

    Weitzman, Morley

    1992-07-15

    A three-dimensional finite-element code was developed and used to simulate the flow of groundwater towards an excavation in a saturated porous medium, allowing for seepage faces. An iterative procedure was used to predict the movement of the water table and the seepage flux. The numerical solution agreed well with experimental results from a sandbox experiment. (auth)

  5. Radiocarbon dating of charred human bone remains preserved in urns excavated from medieval Buddhist cemetery in Japan

    Energy Technology Data Exchange (ETDEWEB)

    Nakamura, Toshio, E-mail: nakamura@nendai.nagoya-u.ac.j [Center for Chronological Research, Nagoya University, Chikusa, Nagoya 464-8602 (Japan); Sagawa, Shinichi; Yamada, Tetsuya [Gangoji Institute for Research of Cultural Properties, Nakain, Nara 630-8392 (Japan); Kanehara, Masaaki [School of Science Education, Nara University of Education, Takabatake, Nara 630-8528 (Japan); Tsuchimoto, Norio [Ichinomiya City Museum, Yamato, Ichinomiya 491-0922 (Japan); Minami, Masayo [Center for Chronological Research, Nagoya University, Chikusa, Nagoya 464-8602 (Japan); Omori, Takayuki [Graduate School of Environmental Studies, Nagoya University, Chikusa, Nagoya 464-8602 (Japan); Okuno, Mitsuru [Faculty of Science, Fukuoka University, Jonan, Fukuoka 814-0180 (Japan); Ohta, Tomoko [Center for Chronological Research, Nagoya University, Chikusa, Nagoya 464-8602 (Japan)

    2010-04-15

    For a preliminary test of {sup 14}C dating of cremated human remains, we have collected charred bone and wood-charcoal fragments from cremated remains contained in cinerary urns that had been excavated from medieval Buddhist cemetery at the Hoenji temple in Aichi prefecture, central Japan. More than 230 urn vessels were discovered from the excavated area of ca. 14 m wide and 14 m long. The identification of charred bone or charcoal fragments among the remains was performed by observation of surface appearance, inspection of fine structures by a microscope, bubble formation during the HCl treatments in preparing target material for AMS {sup 14}C dating, carbon and nitrogen contents, delta{sup 13}C and delta{sup 15}N values of the fragments. All {sup 14}C ages obtained for the samples that were identified as charred bone remains were almost consistent with the archeological age estimated based on typological analysis of respective urns. On the other hand, some {sup 14}C ages for the remains identified as wood charcoal, which had been produced from firewood or a wooden coffin during the cremation, were not consistent with archeological estimation, shifting toward older {sup 14}C ages, most probably as the result of old wood effect.

  6. Age-related elemental change in bones

    Energy Technology Data Exchange (ETDEWEB)

    Wang, C.; Eisa, M.H. [Institute of Modern Physics, Fudan University, Shanghai 200433 (China); Jin, W. [Institute of Radiation Medicine, Fudan University, Shanghai 200032 (China); Shen, H. [Institute of Modern Physics, Fudan University, Shanghai 200433 (China)], E-mail: haoshen@fudan.edu.cn; Mi, Y. [Institute of Modern Physics, Fudan University, Shanghai 200433 (China); Gao, J.; Zhou, Y. [Institute of Radiation Medicine, Fudan University, Shanghai 200032 (China); Yao, H. [Institute of Modern Physics, Fudan University, Shanghai 200433 (China); Zhao, Y. [Institute of High Energy Physics, Beijing 100049 (China)

    2008-04-15

    To investigate age dependence of the bone element contents and structure, lumbar and femur from Sprague-Dawley (SD) rats were chosen for their more susceptibility to fracture. These rats were divided into to 5 age groups: 1, 4, 7, 11 and 25 month-age, corresponding human beings from the young to the old. The elements contents were detected by external Proton Induced X-ray emission (PIXE) technique. X-ray Absorption Fine Structure (XAFS) method was also applied to obtain information about calcium (Ca) and phosphor (P) structure. It was found that Ca content, Ca/P ratio, valance state of Ca and P and their coordinate structure remains unaltered with age variance, whereas the content of strontium (Sr) was significantly decreasing. Sr concentration may provide a new parameter for diagnosis of bone disorder.

  7. DNA FROM ANCIENT STONE TOOLS AND BONES EXCAVATED AT BUGAS-HOLDING, WYOMING

    Science.gov (United States)

    Traces of DNA may preserve on ancient stone tools. We examined 24 chipped stone artifacts recovered from the Bugas-Holding site in northwestern Wyoming for the presence of DNA residues, and we compared DNA preservation in bones and stone tools from the same stratigraphic context...

  8. Finite element analysis of bone loss around failing implants

    NARCIS (Netherlands)

    Wolff, J.; Narra, N.; Antalainen, A.K.; Valášek, J.; Kaiser, J.; Sandór, G.K.; Marcián, P.

    2014-01-01

    Dental implants induce diverse forces on their surrounding bone. However, when excessive unphysiological forces are applied, resorption of the neighbouring bone may occur. The aim of this study was to assess possible causes of bone loss around failing dental implants using finite element analysis. A

  9. An Analysis of Systematic Elemental Changes in Decomposing Bone.

    Science.gov (United States)

    Walden, Steven J; Mulville, Jacqui; Rowlands, Jeffrey P; Evans, Sam L

    2017-03-10

    The aim of this pilot study was to investigate compositional changes in bone during decomposition. Elemental concentrations of barium, calcium, iron, potassium, magnesium, zinc and phosphorus in porcine bone (as an experimental analog for human bone) were analyzed by inductively coupled plasma optical emission spectroscopy (ICP-OES). The samples were taken from porcine bone subjected to shallow burial and surface depositions at 28-day intervals for a period of 140 days. Results indicated that ICP-OES elemental profiling has potential to be developed as a forensic test for determining whether a bone sample originates from the early stages of soft tissue putrefaction. Significant changes in iron, sodium and potassium concentrations were found over 140 days. These elements are known to be primarily associated with proteins and/or tissue fluids within the bone. Changes in their respective concentrations may therefore be linked to dehydration over time and in turn may be indicative of time since deposition.

  10. OPTIMIZING UPPER EXCAVATOR

    Directory of Open Access Journals (Sweden)

    Dragos Vasile VÎGA

    2016-05-01

    Full Text Available An essential element when establishing the balance of a bucket wheel excavator is the determination of the barycentre, the best results being thus obtained by weighting after having installed all the components. The lack of correct balance for bucket wheel excavators determines their operation in an inadequate dynamic mode, or in extreme cases, there is the danger of losing stability by tilting over the excavator respectively suffering huge material and human loss. It is compulsory to verify for the correctness of the position and mass value of balance because there might be substantial error sources leading to compromise the operation. One of the most popular methods is that of weighting the entire equipment from the superior platform of the excavator. The weighting process implies the lifting of the excavators in three spots with hydraulic cylinders, the measurement of the forces, as well as the measurement of pressure inside the cylinders and of the stroke of each cylinder. The data measurement and rehashing installation is destined to determine the dimensions that finally define the weighting process of excavators or other operating machineries to which the balancing and control of stability is imposed.

  11. Connecting mechanics and bone cell activities in the bone remodeling process: an integrated finite element modeling.

    Science.gov (United States)

    Hambli, Ridha

    2014-01-01

    Bone adaptation occurs as a response to external loadings and involves bone resorption by osteoclasts followed by the formation of new bone by osteoblasts. It is directly triggered by the transduction phase by osteocytes embedded within the bone matrix. The bone remodeling process is governed by the interactions between osteoblasts and osteoclasts through the expression of several autocrine and paracrine factors that control bone cell populations and their relative rate of differentiation and proliferation. A review of the literature shows that despite the progress in bone remodeling simulation using the finite element (FE) method, there is still a lack of predictive models that explicitly consider the interaction between osteoblasts and osteoclasts combined with the mechanical response of bone. The current study attempts to develop an FE model to describe the bone remodeling process, taking into consideration the activities of osteoclasts and osteoblasts. The mechanical behavior of bone is described by taking into account the bone material fatigue damage accumulation and mineralization. A coupled strain-damage stimulus function is proposed, which controls the level of autocrine and paracrine factors. The cellular behavior is based on Komarova et al.'s (2003) dynamic law, which describes the autocrine and paracrine interactions between osteoblasts and osteoclasts and computes cell population dynamics and changes in bone mass at a discrete site of bone remodeling. Therefore, when an external mechanical stress is applied, bone formation and resorption is governed by cells dynamic rather than adaptive elasticity approaches. The proposed FE model has been implemented in the FE code Abaqus (UMAT routine). An example of human proximal femur is investigated using the model developed. The model was able to predict final human proximal femur adaptation similar to the patterns observed in a human proximal femur. The results obtained reveal complex spatio-temporal bone

  12. Biochemical and physical correlates of DNA contamination in archaeological human bones and teeth excavated at Matera, Italy

    DEFF Research Database (Denmark)

    Gilbert, M. T. P.; Rudbeck, L.; Willerslev, E.

    2005-01-01

    The majority of ancient DNA studies on human specimens have utilised teeth and bone as a source of genetic material. In this study the levels of endogenous contamination (i.e. present within the sample prior to sampling for the DNA analysis) are assessed within human bone and teeth specimens...... sampled from the cemetery of Santa Lucia alle Malve, Matera, Italy. This site is of exceptional interest, because the samples have been assayed for IS measures of biochemical and physical preservation, and it is the only one identified in a study of more than 107 animal and 154 human bones from 43 sites...... across Europe, where a significant number of human bones was well preserved. The findings demonstrate several important issues: (a) although teeth are more resilient to contamination than bone, both are readily contaminated (presumably through handling or washing), and (b) once contaminated in this way...

  13. A continuum mechanics-based framework for optimizing boundary and finite element meshes associated with underground excavations-framework

    Science.gov (United States)

    Zsáki, Attila M.; Curran, John H.

    2005-11-01

    Many field problems, from stress analysis, heat transfer to contaminant transport, deal with disturbances in a continuum caused by a source (defined by its discrete geometry) and a region of interest (where a solution is sought). Depending on the location of regions of interest in relation to the sources, the level of geometric detail necessary to represent the sources in a model can vary considerably. A practical application of stress analysis in mining is the evaluation of the effects of continuous excavation on the states of stress around mine openings. Labour intensive model preparation and lengthy computation coupled with the interpretation of analysis results can have considerable impact on the successful operation of an underground mine, where stope failures can cost tens of millions of dollars and possibly lead to closure of the mine.A framework is proposed based on continuum mechanics principles to automatically optimize the level of geometric detail required for an analysis by simplifying the model geometry using expanded and modified algorithms that originated in computer graphics. This reduction in model size directly translates to savings in computational time. The results obtained from an optimized model have accuracy comparable to the uncertainty in input data (e.g. rock mass properties, geology, etc.). This first paper defines the optimization framework, while a companion paper investigates its efficiency and application to practical mining and excavation-related problems. Copyright

  14. Concentration of Key Elements in North American Meat & Bone Meal

    Science.gov (United States)

    Meat & bone meal (MBM) and related rendered protein commodities have potential for use in applications other than animal feed, including use as a fuel or a phosphorus fertilizer. In order to develop these applications, data on the elemental composition are required; the currently available elementa...

  15. Elemental and structural studies at the bone-cartilage interface

    Energy Technology Data Exchange (ETDEWEB)

    Kaabar, W., E-mail: w.kaabar@surrey.ac.uk [Department of Physics, University of Surrey, Guildford GU2 7XH (United Kingdom); Daar, E. [Department of Physics, University of Surrey, Guildford GU2 7XH (United Kingdom); Bunk, O. [Swiss Light Source, Paul Scherrer Institute, 5232 Villigen (Switzerland); Farquharson, M.J. [Department of Medical Physics and Applied Radiation Sciences, McMaster University, 1280 Main Street West, Hamilton, Ontario, L8S 4K1 (Canada); Laklouk, A. [Al-Fateh University, Tripoli (Libya); Bailey, M.; Jeynes, C. [Surrey Ion Beam Centre, University of Surrey, Guildford GU2 7XH (United Kingdom); Gundogdu, O. [Umuttepe Campus, University of Kocaeli, 41380 Kocaeli (Turkey); Bradley, D.A. [Department of Physics, University of Surrey, Guildford GU2 7XH (United Kingdom)

    2011-10-01

    Micro-Proton Induced X-ray Emission ({mu}-PIXE) and Proton Induced Gamma-ray Emission (PIGE) techniques were employed in the investigation of trace and essential elements distribution in normal and diseased human femoral head sections affected by osteoarthritis (OA). PIGE was exploited in the determination of elements of low atomic number z<15 such as Na and F whereas elements with z>15 viz Ca, Z, P and S were determined by PIXE. Accumulations of key elements in the bone and cartilage sections were observed, significant S and Na concentrations being found in the cartilage region particularly in normal tissues. Zn showed enhanced concentrations at the bone-cartilage interface. At a synchrotron facility, small angle X-ray scattering (SAXS) was utilized on a decalcified human femoral head section affected by OA, direct measurements being made of spatial alterations of collagen fibres. The SAXS results showed a slight decrease in the axial periodicity between normal collagen type I and that in diseased tissue in various sites, in contrast with the findings of others.

  16. Reconstructing Ancient Egyptian Diet through Bone Elemental Analysis Using LIBS (Qubbet el Hawa Cemetery

    Directory of Open Access Journals (Sweden)

    Ghada Darwish Al-Khafif

    2015-01-01

    Full Text Available One of the most important advantages of LIBS that make it suitable for the analysis of archeological materials is that it is a quasi-nondestructive technique. Archeological mandibles excavated from Qubbet el Hawa Cemetery, Aswan, were subjected to elemental analysis in order to reconstruct the dietary patterns of the middle class of the Aswan population throughout three successive eras: the First Intermediate Period (FIP, the Middle Kingdom (MK, and the Second Intermediate Period (SIP. The bone Sr/Ca and Ba/Ca ratios were significantly correlated, so the Sr/Ca ratios are considered to represent the ante-mortem values. It was suggested that the significantly low FIP Sr/Ca compared to that of both the MK and the SIP was attributed to the consumption of unusual sorts of food and imported cereals during years of famine, while the MK Sr/Ca was considered to represent the amelioration of climatic, social, economic, and political conditions in this era of state socialism. The SIP Sr/Ca, which is nearly the same as that of the MK, was considered to be the reflection of the continuity of the individualism respect and state socialism and a reflection of agriculture conditions amelioration under the reign of the 17th Dynasty in Upper Egypt.

  17. Excavator Design Validation

    Science.gov (United States)

    Pholsiri, Chalongrath; English, James; Seberino, Charles; Lim, Yi-Je

    2010-01-01

    element models and fast analytical models. By using the first to establish parameters for the second, a system has been created that can be executed in real time, or faster than real time, on a desktop PC. This allows Monte Carlo simulations to be performed on a computer platform available to all researchers, and it allows human interaction to be included in a real-time simulation process. Metrics on excavator performance are established that work with the simulation architecture. Both static and dynamic metrics are included.

  18. Probabilistic Study of Bone Remodeling Using Finite Element Analysis

    Science.gov (United States)

    Werner, C.; Gorla, R. S. R.

    2013-08-01

    The dynamic bone remodeling process is a computationally challenging research area that struggles to understand the actual mechanisms. It has been observed that a mechanical stimulus in the bone greatly affects the remodeling process. A 3D finite element model of a femur is created and a probabilistic analysis is performed on the model. The probabilistic analysis measures the sensitivities of various parameters related to the material properties, geometric properties, and the three load cases defined as Single Leg Stance, Abduction, and Adduction. The sensitivity of each parameter is based on the calculated maximum mechanical stimulus and analyzed at various values of probabilities ranging from 0.001 to 0.999. The analysis showed that the parameters associated with the Single Leg Stance load case had the highest sensitivity with a probability of 0.99 and the angle of the force applied to the joint of the proximal femur had the overall highest sensitivity

  19. Evaluation of elemental status of ancient human bone samples from Northeastern Hungary dated to the 10th century AD by XRF

    Science.gov (United States)

    János, I.; Szathmáry, L.; Nádas, E.; Béni, A.; Dinya, Z.; Máthé, E.

    2011-11-01

    The present study is a multielemental analysis of bone samples belonging to skeletal individuals originating from two contemporaneous (10th century AD) cemeteries (Tiszavasvári Nagy-Gyepáros and Nagycserkesz-Nádasibokor sites) in Northeastern Hungary, using the XRF analytical technique. Emitted X-rays were detected in order to determine the elemental composition of bones and to appreciate the possible influence of the burial environment on the elemental content of the human skeletal remains. Lumbar vertebral bodies were used for analysis. Applying the ED(P)XRF technique concentration of the following elements were determined: P, Ca, K, Na, Mg, Al, Cl, Mn, Fe, Zn, Br and Sr. The results indicated post mortem mineral exchange between the burial environment (soil) and bones (e.g. the enhanced levels of Fe and Mn) and referred to diagenetic alteration processes during burials. However, other elements such as Zn, Sr and Br seemed to be accumulated during the past life. On the basis of statistical analysis, clear separation could not be observed between the two excavation sites in their bone elemental concentrations which denoted similar diagenetic influences, environmental conditions. The enhanced levels of Sr might be connected with the past dietary habits, especially consumption of plant food.

  20. Evolution of the heterogeneous structure of 1999 Mw 7.6 Chi-Chi earthquake thrust in Chushan excavation site, central Taiwan, based on distinct element models

    Science.gov (United States)

    Hsu, Chia-Hsiang; Huang, Wen-Jeng; Chang, Yu-Yi; Nien, Wei-Tung; Huang, Wen-Chao

    2016-04-01

    Exposures in the Chushan trench, 40 m long and 10 m deep, excavated across a 1999 earthquake-induced escarpment of 2 m high, show a steep, monocline-like fold with significantly different limb-truncated structures on either side of the 14 m wide trench. On southern exposure the fold is truncated through along the axial trace of its anticline by a fault branch with a dip angle of 32° and a maximum separation of ~4.2 m while on the northern exposure the steep limb of the fold is displaced up to ~3.0 m along the axial trace of its syncline by another fault branch with a dip angle of 24°. This study intends to explore how this heterogeneous structure might form using distinct element simulation of blind reverse faulting. All our models in this study consist of two mechanical layers, including an upper clayey layer of 7 meters thickness and a lower gravelly layer of 8 meters thickness at maximum, as revealed by the excavation, a borehole nearby and soil tests. Our results show that the steep, monocline-like fold can be simulated by a low-angle reverse faulting similar to a subsurface dominant fault with a dip angle of 24° derived from the trench site at the ground surface and in a borehole in the hanging wall. Furthermore, the different structures on the two exposures were mainly controlled by the dip-angle variation of the upper part of the subsurface dominant fault. The simulation of reverse faulting with a dip angle of 24°shows a monocline forms in the clayey layer, and then a gravelly wedge starts to protrude into the clayey layer and displace it along the axial trace of the anticline similar to the structure on the southern exposure, and the simulation of reverse faulting with a dip angle of 32°shows a monocline forms in the clayey layer, and then this monoclonal clayey layer starts to be displaced along the axial trace of the synclinal by a newly fault similar to the structure on the northern exposure. We also find the strength of clayey layer and the

  1. The Distribution of Elements in 48 Canine Compact Bone Types Using Handheld X-Ray Fluorescence.

    Science.gov (United States)

    Nganvongpanit, Korakot; Buddhachat, Kittisak; Piboon, Promporn; Klinhom, Sarisa

    2016-11-01

    A major question when we talk about the elements in the bone is whether all bones contain the same elements. To answer this question, this study was designed for determination of the elemental levels in 48 various canine compact bones using handheld X-ray fluorescence technique. From a total of 26 elements that could be detected, only 13 elements were found in all 48 bones. The sternum and os penis were significantly different from the other bones in that they contained the highest number of elements. The ratio of Ca and P was significantly different when comparing certain bones: there was a higher Ca/P ratio in the patella (right), calcaneus (right and left), and sternum compared with a lower ratio in the radius (left), rib (left), phalanx (left forelimb), and carpus (left). These results are the first to demonstrate that different types of bones have different elemental profiles, even for major elements such as Ca and P. Moreover, the Ca/P ratio was also different between bone types. This data is important for the selection of bones appropriate to the element studied. In addition, the results proved that the elements were not equally distributed in every bone in the body.

  2. Lightweight Robotic Excavation Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Robust, lightweight, power-efficient excavation robots are mission enablers for lunar outposts and surface systems. Lunar excavators of this type cost-effectively...

  3. The distribution of mercury and other trace elements in the bones of two human individuals from medieval Denmark – the chemical life history hypothesis

    DEFF Research Database (Denmark)

    Rasmussen, Kaare Lund; Skytte, Lilian; Pilekær, Christian

    2013-01-01

    Excavating human skeletons is the closest archaeologists can get to the people who lived in the past. Once excavated the bones are often analysed chemically in order to yield as much information as possible. Most archaeometric analyses performed on samples of human skeletal remains have been perf...

  4. Elemental and structural studies at the bone-cartilage interface

    Science.gov (United States)

    Bradley, D. A.; Kaabar, W.; Gundogdu, O.

    2012-02-01

    The techniques μProton-Induced X-and γ-ray Emission, μ-PIXE and μ-PIGE, were used to investigate trace and essential element distributions in sections of normal and osteoarthritic (OA) human femoral head. μ-PIGE yielded 2-D mappings of Na and F while Ca, Z, P and S were mapped by μ-PIXE. The concentration of chondroitin sulphate supporting functionality in healthy cartilage is significantly reduced in OA samples. Localised Zn points to osteoblastic/osteoclastic activity at the bone-cartilage interface. Small-angle X-ray scattering applied to decalcified OA-affected tissue showed spatial alterations of collagen fibres of decreased axial periodicity compared to normal collagen type I.

  5. Can experimental data in humans verify the finite element-based bone remodeling algorithm?

    DEFF Research Database (Denmark)

    Wong, C.; Gehrchen, P.M.; Kiaer, T.

    2008-01-01

    STUDY DESIGN: A finite element analysis-based bone remodeling study in human was conducted in the lumbar spine operated on with pedicle screws. Bone remodeling results were compared to prospective experimental bone mineral content data of patients operated on with pedicle screws. OBJECTIVE......: The validity of 2 bone remodeling algorithms was evaluated by comparing against prospective bone mineral content measurements. Also, the potential stress shielding effect was examined using the 2 bone remodeling algorithms and the experimental bone mineral data. SUMMARY OF BACKGROUND DATA: In previous studies......, in the human spine, the bone remodeling algorithms have neither been evaluated experimentally nor been examined by comparing to unsystematic experimental data. METHODS: The site-specific and nonsite-specific iterative bone remodeling algorithms were applied to a finite element model of the lumbar spine...

  6. Anatomy, histology and elemental profile of long bones and ribs of the Asian elephant (Elephas maximus).

    Science.gov (United States)

    Nganvongpanit, Korakot; Siengdee, Puntita; Buddhachat, Kittisak; Brown, Janine L; Klinhom, Sarisa; Pitakarnnop, Tanita; Angkawanish, Taweepoke; Thitaram, Chatchote

    2017-09-01

    This study evaluated the morphology and elemental composition of Asian elephant (Elephas maximus) bones (humerus, radius, ulna, femur, tibia, fibula and rib). Computerized tomography was used to image the intraosseous structure, compact bones were processed using histological techniques, and elemental profiling of compact bone was conducted using X-ray fluorescence. There was no clear evidence of an open marrow cavity in any of the bones; rather, dense trabecular bone was found in the bone interior. Compact bone contained double osteons in the radius, tibia and fibula. The osteon structure was comparatively large and similar in all bones, although the lacuna area was greater (P < 0.05) in the femur and ulna. Another finding was that nutrient foramina were clearly present in the humerus, ulna, femur, tibia and rib. Twenty elements were identified in elephant compact bone. Of these, ten differed significantly across the seven bones: Ca, Ti, V, Mn, Fe, Zr, Ag, Cd, Sn and Sb. Of particular interest was the finding of a significantly larger proportion of Fe in the humerus, radius, fibula and ribs, all bones without an open medullary cavity, which is traditionally associated with bone marrow for blood cell production. In conclusion, elephant bones present special characteristics, some of which may be important to hematopoiesis and bone strength for supporting a heavy body weight.

  7. Finite element analysis for the arm of hydraulic excavators based on ABAQUS%应用 ABAQUS 的液压挖掘机动臂有限元分析

    Institute of Scientific and Technical Information of China (English)

    蒋小利; 江志刚; 张华; 胡晓莉

    2014-01-01

    The arm is a main component of a hydraulic excavator for completing the function ,the reasonability of the structure will directly affect the working performance and reliability of the hydraulic excavator .However,using the finite element method for structural analysis of excavator arm is the premise for ensuring the rationality for the structural design of the arm .Taking a certain type of hydraulic excavator(20t)as the research object,using finite element analysis software ABAQUS to carry out finite element analysis on its arm ,from which the cloud atlas of stress and deform was obtained .The analysis results show that the strength and stiffness for the arm was sufficient and theoretical guidance for the design and test of the arm was provided .%液压挖掘机动臂是完成液压挖掘机各项功能的主要构件,其结构设计的合理性直接关系到液压挖掘机的工作性能和可靠性。基于有限元分析方法的液压挖掘机动臂结构分析是保证液压挖掘机动臂结构设计合理性的前提,以某型液压挖掘机(20 t级)为研究对象,应用有限元分析软件ABAQUS对其动臂进行有限元分析,求得危险工况下该动臂的应力云图与位移云图,通过云图分析动臂的强度和刚度,为动臂的设计和试验提供参考。

  8. Can experimental data in humans verify the finite element-based bone remodeling algorithm?

    DEFF Research Database (Denmark)

    Wong, Christian; Gehrchen, P Martin; Kiaer, Thomas

    2008-01-01

    A finite element analysis-based bone remodeling study in human was conducted in the lumbar spine operated on with pedicle screws. Bone remodeling results were compared to prospective experimental bone mineral content data of patients operated on with pedicle screws....

  9. 复合土钉支护深基坑稳定性及变形的有限元分析%Finite Element Analysis of Stability and Deformation of Composite Soil Nailing for Deep Excavation

    Institute of Scientific and Technical Information of China (English)

    王翠英; 刘安安; 王旭

    2012-01-01

    The foundation pit project of Quanfudadi business-living building in Quanzhou was taken as an example,and based on the analysis of the general situation of the foundation pit project,the formation structures and the supporting types as well as the around environment conditions,software SLI DE was used to analyze the stability of the composite soil nailing supporting excavation in accordance with the working mechanism of the composite soil nailing.The SIGMA/W module of GEO-Studio software was applied to perform a series of finite element analyses on the deformation characteristics of composite soil nailing supporting excavation.The results show that the stability and deformation are close to the field monitoring results for deep excavation.The finite element method is of important significance in information construction for deep excavation.%以泉州泉府大第商住楼基坑工程为实例,在充分研究深基坑工程概况、地层结构、支护形式及周边环境条件的基础上,基于复合土钉支护的工作原理,运用SLIDE软件对复合土钉支护深基坑进行稳定性分析,以GEO-Studio中的SIGMA/W模块进行变形特征的有限元分析,结果表明该基坑的稳定状态及变形与实际监测结果接近,该方法对基坑开挖支护过程中信息化指导施工具有实用价值.

  10. Multiscale approach for bone remodeling simulation based on finite element and neural network computation

    CERN Document Server

    Hambli, Ridha

    2011-01-01

    The aim of this paper is to develop a multiscale hierarchical hybrid model based on finite element analysis and neural network computation to link mesoscopic scale (trabecular network level) and macroscopic (whole bone level) to simulate bone remodelling process. Because whole bone simulation considering the 3D trabecular level is time consuming, the finite element calculation is performed at macroscopic level and a trained neural network are employed as numerical devices for substituting the finite element code needed for the mesoscale prediction. The bone mechanical properties are updated at macroscopic scale depending on the morphological organization at the mesoscopic computed by the trained neural network. The digital image-based modeling technique using m-CT and voxel finite element mesh is used to capture 2 mm3 Representative Volume Elements at mesoscale level in a femur head. The input data for the artificial neural network are a set of bone material parameters, boundary conditions and the applied str...

  11. [Sutural physical model building in the three-dimensional finite-element model of maxillofacial bones].

    Science.gov (United States)

    Liu, Chang; Zhu, Xian-chun; Zhang, Xing; Tai, Yin-xia; Yan, Sen

    2011-02-01

    To build the physical model of four suturae which are related to the growth of maxilla in the three-dimensional finite-element model of maxillofacial bones. A 16 years old volunteer with individual normal occlusion, good periodontium health condition and without diseases of temporomandibular joint was chosen to be the material of modeling. The three-dimensional finite-element model of the volunteer's maxillofacial bones was built using the CT scan and the finite-element modeling method. Finally we built the physical model of four suturae which were related to the growth of maxilla in the model of maxillofacial bones. The model of maxillofacial bones with 86,575 nodes and 485,915 elements was generated. This model contained four suturae including sutura frontomaxillaris, sutura zygomaticomaxillaris, sutura temporozygomatica and sutura pterygopalatine. A three-dimensional finite-element model of maxillofacial bones with good biological similarity was developed.

  12. Multi-Elemental Profiling of Tibial and Maxillary Trabecular Bone in Ovariectomised Rats.

    Science.gov (United States)

    Han, Pingping; Lu, Shifeier; Zhou, Yinghong; Moromizato, Karine; Du, Zhibin; Friis, Thor; Xiao, Yin

    2016-01-01

    Atomic minerals are the smallest components of bone and the content of Ca, being the most abundant mineral in bone, correlates strongly with the risk of osteoporosis. Postmenopausal women have a far greater risk of suffering from OP due to low Ca concentrations in their bones and this is associated with low bone mass and higher bone fracture rates. However, bone strength is determined not only by Ca level, but also a number of metallic and non-metallic elements in bone. Thus, in this study, the difference of metallic and non-metallic elements in ovariectomy-induced osteoporosis tibial and maxillary trabecular bone was investigated in comparison with sham operated normal bone by laser ablation inductively-coupled plasma mass spectrometry using a rat model. The results demonstrated that the average concentrations of (25)Mg, (28)Si, (39)K, (47)Ti, (56)Fe, (59)Co, (77)Se, (88)Sr, (137)Ba, and (208)Pb were generally higher in tibia than those in maxilla. Compared with the sham group, Ovariectomy induced more significant changes of these elements in tibia than maxilla, indicating tibial trabecular bones are more sensitive to changes of circulating estrogen. In addition, the concentrations of (28)Si, (77)Se, (208)Pb, and Ca/P ratios were higher in tibia and maxilla in ovariectomised rats than those in normal bone at all time-points. The present study indicates that ovariectomy could significantly impact the element distribution and concentrations between tibia and maxilla.

  13. Multi-Elemental Profiling of Tibial and Maxillary Trabecular Bone in Ovariectomised Rats

    Directory of Open Access Journals (Sweden)

    Pingping Han

    2016-06-01

    Full Text Available Atomic minerals are the smallest components of bone and the content of Ca, being the most abundant mineral in bone, correlates strongly with the risk of osteoporosis. Postmenopausal women have a far greater risk of suffering from OP due to low Ca concentrations in their bones and this is associated with low bone mass and higher bone fracture rates. However, bone strength is determined not only by Ca level, but also a number of metallic and non-metallic elements in bone. Thus, in this study, the difference of metallic and non-metallic elements in ovariectomy-induced osteoporosis tibial and maxillary trabecular bone was investigated in comparison with sham operated normal bone by laser ablation inductively-coupled plasma mass spectrometry using a rat model. The results demonstrated that the average concentrations of 25Mg, 28Si, 39K, 47Ti, 56Fe, 59Co, 77Se, 88Sr, 137Ba, and 208Pb were generally higher in tibia than those in maxilla. Compared with the sham group, Ovariectomy induced more significant changes of these elements in tibia than maxilla, indicating tibial trabecular bones are more sensitive to changes of circulating estrogen. In addition, the concentrations of 28Si, 77Se, 208Pb, and Ca/P ratios were higher in tibia and maxilla in ovariectomised rats than those in normal bone at all time-points. The present study indicates that ovariectomy could significantly impact the element distribution and concentrations between tibia and maxilla.

  14. Smart Calibration of Excavators

    DEFF Research Database (Denmark)

    Bro, Marie; Døring, Kasper; Ellekilde, Lars-Peter

    2005-01-01

    Excavators dig holes. But where is the bucket? The purpose of this report is to treat four different problems concerning calibrations of position indicators for excavators in operation at concrete construction sites. All four problems are related to the question of how to determine the precise ge...

  15. Principles of Mechanical Excavation

    Energy Technology Data Exchange (ETDEWEB)

    Lislerud, A. [Tamrock Corp., Tampere (Finland)

    1997-12-01

    Mechanical excavation of rock today includes several methods such as tunnel boring, raiseboring, roadheading and various continuous mining systems. Of these raiseboring is one potential technique for excavating shafts in the repository for spent nuclear fuel and dry blind boring is promising technique for excavation of deposition holes, as demonstrated in the Research Tunnel at Olkiluoto. In addition, there is potential for use of other mechanical excavation techniques in different parts of the repository. One of the main objectives of this study was to analyze the factors which affect the feasibility of mechanical rock excavation in hard rock conditions and to enhance the understanding of factors which affect rock cutting so as to provide an improved basis for excavator performance prediction modeling. The study included the following four main topics: (a) phenomenological model based on similarity analysis for roller disk cutting, (b) rock mass properties which affect rock cuttability and tool life, (c) principles for linear and field cutting tests and performance prediction modeling and (d) cutter head lacing design procedures and principles. As a conclusion of this study, a test rig was constructed, field tests were planned and started up. The results of the study can be used to improve the performance prediction models used to assess the feasibility of different mechanical excavation techniques at various repository investigation sites. (orig.). 21 refs.

  16. Strain energy density gradients in bone marrow predict osteoblast and osteoclast activity: a finite element study.

    Science.gov (United States)

    Webster, Duncan; Schulte, Friederike A; Lambers, Floor M; Kuhn, Gisela; Müller, Ralph

    2015-03-18

    Huiskes et al. hypothesized that mechanical strains sensed by osteocytes residing in trabecular bone dictate the magnitude of load-induced bone formation. More recently, the mechanical environment in bone marrow has also been implicated in bone׳s response to mechanical stimulation. In this study, we hypothesize that trabecular load-induced bone formation can be predicted by mechanical signals derived from an integrative µFE model, incorporating a description of both the bone and marrow phase. Using the mouse tail loading model in combination with in vivo micro-computed tomography (µCT) we tracked load induced changes in the sixth caudal vertebrae of C57BL/6 mice to quantify the amount of newly mineralized and eroded bone volumes. To identify the mechanical signals responsible for adaptation, local morphometric changes were compared to micro-finite element (µFE) models of vertebrae prior to loading. The mechanical parameters calculated were strain energy density (SED) on trabeculae at bone forming and resorbing surfaces, SED in the marrow at the boundary between bone forming and resorbing surfaces, along with SED in the trabecular bone and marrow volumes. The gradients of each parameter were also calculated. Simple regression analysis showed mean SED gradients in the trabecular bone matrix to significantly correlate with newly mineralized and eroded bone volumes R(2)=0.57 and 0.41, respectively, pbone marrow plays a significant role in determining osteoblast and osteoclast activity.

  17. Lightweight Robotic Excavation Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Lightweight robotic excavators address the need for machines that dig, collect, transport and dump lunar soil. Robust and productive small robots enable mining rich...

  18. Lunar Excavator Validation Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Energid Technologies proposes to create a tool for simulation-based verification of lunar excavator designs. Energid will combine the best of 1) automatic control...

  19. Integration of a Finite Element Model with the DAP Bone Remodeling Model to Characterize Bone Response to Skeletal Loading

    Science.gov (United States)

    Werner, Christopher R.; Mulugeta, Lealem; Myers, J. G.; Pennline, J. A.

    2015-01-01

    NASA's Digital Astronaut Project (DAP) has developed a bone remodeling model that has been validated for predicting volumetric bone mineral density (vBMD) changes of trabecular and cortical bone in the absence of mechanical loading. The model was recently updated to include skeletal loading from exercise and free living activities to maintain healthy bone using a new daily load stimulus (DLS). This new formula was developed based on an extensive review of existing DLS formulas, as discussed in the abstract by Pennline et al. The DLS formula incorporated into the bone remodeling model utilizes strains and stress calculated from finite element model (FEM) of the bone region of interest. The proximal femur was selected for the initial application of the DLS formula, with a specific focus on the femoral neck. METHODS: The FEM was generated from CAD geometry of a femur using de-identified CT data. The femur was meshed using linear tetrahedral elements Figure (1) with higher mesh densities in the femoral neck region, which is the primary region of interest for the initial application of the DLS formula in concert with the DAP bone remodeling model. Nodal loads were applied to the femoral head and the greater trochanter and the base of the femur was held fixed. An L2 norm study was conducted to reduce the length of the femoral shaft without significantly impacting the stresses in the femoral neck. The material properties of the FEM of the proximal femur were separated between cortical and trabecular regions to work with the bone remodeling model. Determining the elements with cortical material properties in the FEM was based off of publicly available CT hip scans [4] that were segmented, cleaned, and overlaid onto the FEM.

  20. Sacred activity by the Method of Excavation

    Directory of Open Access Journals (Sweden)

    Eliana Anjos Furtado

    2014-04-01

    Full Text Available Excavation is a clinical and teaching methodology created by the first author of this article. It constitutes a way of helping subjects think, make and speak. This process occurs through the xcavation of making, unblinding and/or unveiling elements in search for the understanding of sacred activity. Through xcavation, subjects understand their thoughts, values and the society in which they live in as they excavate their life stories and their relations with making, including their daily, social and work activities. We applied a thoughtful analysis to approach the role of excavation and the concept of sacred activity. Sacred activity is the core activity of every human being, which is not necessarily the activity we perform in our everyday or work life. Sacred activity is that in which subjects are inserted and experience integrally, genuinely and with no masking. Through sacred activities, subjects surrender, not only to the activity itself, but also to the other, to himself and into himself, by quest. Seeking sacred activity is, therefore, a process of questioning, excavating the routine of subjects, watching and understanding the content of this excavation, replacing and adjusting what is being unveiled, and thus making this activity sacred. In this analysis, we concluded that, by the method of excavation, the sacralization of this action should allow subjects to have tender relationships, and thus be cured.

  1. Stress Distribution on Short Implants at Maxillary Posterior Alveolar Bone Model With Different Bone-to-Implant Contact Ratio: Finite Element Analysis.

    Science.gov (United States)

    Yazicioglu, Duygu; Bayram, Burak; Oguz, Yener; Cinar, Duygu; Uckan, Sina

    2016-02-01

    The aim of this study was to evaluate the stress distribution of the short dental implants and bone-to-implant contact ratios in the posterior maxilla using 3-dimensional (3D) finite element models. Two different 3D maxillary posterior bone segments were modeled. Group 1 was composed of a bone segment consisting of cortical bone and type IV cancellous bone with 100% bone-to-implant contact. Group 2 was composed of a bone segment consisting of cortical bone and type IV cancellous bone including spherical bone design and homogenous tubular hollow spaced structures with 30% spherical porosities and 70% bone-to-implant contact ratio. Four-millimeter-diameter and 5-mm-height dental implants were assumed to be osseointegrated and placed at the center of the segments. Lateral occlusal bite force (300 N) was applied at a 25° inclination to the implants long axis. The maximum von Mises stresses in cortical and cancellous bones and implant-abutment complex were calculated. The von Mises stress values on the implants and the cancellous bone around the implants of the 70% bone-to-implant contact group were almost 3 times higher compared with the values of the 100% bone-to-implant contact group. For clinical reality, use of the 70% model for finite element analysis simulation of the posterior maxilla region better represents real alveolar bone and the increased stress and strain distributions evaluated on the cortical and cancellous bone around the dental implants.

  2. On the distribution of trace element concentrations in multiple bone elements in 10 Danish medieval and post-medieval individuals.

    Science.gov (United States)

    Lund Rasmussen, Kaare; Skytte, Lilian; D'imporzano, Paolo; Orla Thomsen, Per; Søvsø, Morten; Lier Boldsen, Jesper

    2017-01-01

    The differences in trace element concentrations among 19 different bone elements procured from 10 archaeologically derived human skeletons have been investigated. The 10 individuals are dated archaeologically and some by radiocarbon dating to the medieval and post-medieval period, an interval from ca. AD 1150 to ca. AD 1810. This study is relevant for two reasons. First, most archaeometric studies analyze only one bone sample from each individual; so to what degree are the bones in the human body equal in trace element chemistry? Second, differences in turnover time of the bone elements makes the cortical tissues record the trace element concentrations in equilibrium with the blood stream over a longer time earlier in life than the trabecular. Therefore, any differences in trace element concentrations between the bone elements can yield what can be termed a chemical life history of the individual, revealing changes in diet, provenance, or medication throughout life. Thorough decontamination and strict exclusion of non-viable data has secured a dataset of high quality. The measurements were carried out using Inductively Coupled Plasma Mass Spectrometry (for Fe, Mn, Al, Ca, Mg, Na, Ba, Sr, Zn, Pb and As) and Cold Vapor Atomic Absorption Spectroscopy (for Hg) on ca. 20 mg samples. Twelve major and trace elements have been measured on 19 bone elements from 10 different individuals interred at five cemeteries widely distributed in medieval and renaissance Denmark. The ranges of the concentrations of elements were: Na (2240-5660 µg g(-1) ), Mg (440-2490 µg g(-1) ), Al (9-2030 µg g(-1) ), Ca (22-36 wt. %), Mn (5-11450 µg g(-1) ), Fe (32-41850 µg g(-1) ), Zn (69-2610 µg g(-1) ), As (0.4-120 µg g(-1) ), Sr (101-815 µg g(-1) ), Ba (8-880 µg g(-1) ), Hg (7-78730 ng g(-1) ), and Pb (0.8-426 µg g(-1) ). It is found that excess As is mainly of diagenetic origin. The results support that Ba and Sr concentrations are effective provenance or dietary indicators

  3. Drilling in cortical bone: a finite element model and experimental investigations.

    Science.gov (United States)

    Lughmani, Waqas A; Bouazza-Marouf, Kaddour; Ashcroft, Ian

    2015-02-01

    Bone drilling is an essential part of many orthopaedic surgery procedures, including those for internal fixation and for attaching prosthetics. Estimation and control of bone drilling forces are critical to prevent drill-bit breakthrough, excessive heat generation, and mechanical damage to the bone. An experimental and computational study of drilling in cortical bone has been conducted. A 3D finite element (FE) model for prediction of thrust forces experienced during bone drilling has been developed. The model incorporates the dynamic characteristics involved in the process along with geometrical considerations. An elastic-plastic material model is used to predict the behaviour of cortical bone during drilling. The average critical thrust forces and torques obtained using FE analysis are found to be in good agreement with the experimental results.

  4. Optimal parameters to avoid thermal necrosis during bone drilling: A finite element analysis.

    Science.gov (United States)

    Mediouni, Mohamed; Schlatterer, Daniel R; Khoury, Amal; Von Bergen, Tobias; Shetty, Sunil H; Arora, Manit; Dhond, Amit; Vaughan, Neil; Volosnikov, Alexander

    2017-02-09

    The drilling bone may potentially cause excessive frictional heat, which can lead to local bone necrosis. This heat generation and local necrosis has been suggested to contribute to the resorption of bone around the placed screws, ending in loss of screw purchase in the bone and inadvertent loosening and/or the bone-implant construct. In vivo studies on this subject have inherent obstacles not the least of which is controlling the variables and real time bone temperature data acquisition. Theoretical models can be generated using computer software and the inclusion of known constants for the mechanical properties of metal and bone. These known Data points for the variables (drill bit and bone) enables finite element analysis of various bone drilling scenarios. An elastic-plastic three-dimensional (3D) acetabular bone mode was developed and finite element model analysis (FEA) was applied to various simulated drilling procedures. The FEA results clearly indicate that the depth of drilling and the drill speed both have a significant effect on the temperature during drilling procedures. The reduction of the feeding speed leads to a reduction in bone temperature. Our data suggests that reducing the feeding speed regardless of RPMs and pressure applied could be a simple useful and effective way to reduce drilling temperatures. This study is the first step in helping any surgeon who drills bone and places screws to better understand the ideal pressure to apply and drill speed to employ and advance rate to avoid osteonecrosis. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res.

  5. Effect of platform switching on the peri-implant bone: A finite element study

    Science.gov (United States)

    Martínez-González, Amparo; Peiró, Germán; Ródenas, Juan-José; López-Mollá, María-Victoria

    2015-01-01

    Background There exists a relation between the presence and location of the micro-gap and the loss of peri implant bone. Several authors have shown that the treatments based on the use of platform switching result in less peri-implant bone loss and an increased tissue stability. The purpose of this study was to analyse the effect of the platform switching on the distribution of stresses on the peri-implant bone using the finite element method. Material and Methods A realistic 3D full-mandible finite element model representing cortical bone and trabecular bone was used to study the distribution of the stress on the bone induced by an implant of diameter 4.1 mm. Two abutments were modelled. The first one, of diameter 4.1 mm, was used in the reference model to represent a conventional implant. The second one, of diameter 3.2 mm, was used to represent the implant with platform switching. Both models were subjected to axial and oblique masticatory loads. Results The analyses showed that, although no relevant differences can be found for the trabecular bone, the use of platform switching reduces the maximum stress level in the cortical bone by almost 36% with axial loads and by 40% with oblique loads. Conclusions The full 3D Finite Element model, that can be used to investigate the influence of other parameters (implant diameter, connexion type, …) on the biomechanical behaviour of the implant, showed that this stress reduction can be a biomechanical reasons to explain why the platform switching seems to reduce or eliminate crestal bone resorption after the prosthetic restoration. Key words:Dental implant, platform switching, finite element method. PMID:26535094

  6. Validation of an efficient method of assigning material properties in finite element analysis of pelvic bone.

    Science.gov (United States)

    Shim, Vickie B; Battley, Mark; Anderson, Iain A; Munro, Jacob T

    2015-01-01

    Bone in the pelvis is a composite material with a complex anatomical structure that is difficult to model computationally. Rather than assigning material properties to increasingly smaller elements to capture detail in three-dimensional finite element (FE) models, properties can be assigned to Gauss points within larger elements. As part of a validation process, we compared experimental and analytical results from a composite beam under four-point load to FE models with material properties assigned to refined elements and Gauss points within larger elements. Both FE models accurately predicted deformation and the analytical predictions of internal shear stress.

  7. Excavation of LSS1

    CERN Multimedia

    1972-01-01

    Excavation of the long straight-section LSS1 by an Alpine boring machine. View of the connection chamber, in the background, the roofs of the enlarged sections (8.5 m and 6 m). On the right, the access tunnel to PP1.

  8. Three dimensional finite element analysis to detect stress distribution in spiral implants and surrounding bone.

    Science.gov (United States)

    Danza, Matteo; Palmieri, Annalisa; Farinella, Francesca; Brunelli, Giorgio; Carinci, Francesco; Girardi, Ambra; Spinelli, Giuseppe

    2009-01-01

    The aim of research was to study spiral family implant by finite element analysis (FEA) inserted in different bone qualities connected with abutments of different angulations. The biomechanical behaviour of 4.2 × 13 mm dental implants, connecting screw, straight and 15° and 25° angulated abutments subjected to static loads, in contact with high and poor bone qualities was evaluated by FEA. The lowest stress value was found in the system composed by implants and straight abut-ments loaded with a vertical force, while the highest stress value was found in implants with 15° angulated abutment loaded with an angulated force. In addition, we found the lower the bone quality, the higher the distribution of the stress within the bone. Spiral family implants can be used successfully in low bone quality but applying a straight force is recommended.

  9. Morse taper implants at different bone levels: a finite element analysis of stress distribution

    OpenAIRE

    Toniollo, Marcelo Bighetti; Macedo, Ana Paula; Palhares, Daniel; Calefi, Paulo Linares; Sorgini, Danilo Balero; Mattos, Maria da Gloria Chiarello de

    2012-01-01

    AIM: To explore the biomechanical effects of the different implantation bone levels of Morse taper implants, employing a finite element analysis (FEA). METHODS: Dental implants (TitamaxCM) with 4x13 mm and 4x11 mm, and their respective abutments with 3.5 mm height, simulating a screwed premolar metal-ceramic crown, had their design performed using the software AnsysWorkbench 10.0. They were positioned in bone blocks, covered by 2.5 mm thickness of mucosa. The cortical bone was designed with 1...

  10. Microstructure-based Finite Element Modelling and Characterisation of Bovine Trabecular Bone

    Institute of Scientific and Technical Information of China (English)

    R. Akhtar; S. J. Eichhorn; P. M. Mummery

    2006-01-01

    The mechanical behaviour of trabecular bone is dependent on both the properties of individual trabeculae as well as their three-dimensional arrangement in space. In this study, nanoindentation was used to determine trabecular stiffness of bovine bone, both d ehydrated and rehydrated. Values of 18.3 GPa and 14.3 GPa were obtained for dehydrated and rehydrated trabeculae respectively. These values were then used for finite element analysis where the mesh was generated directly from an X-ray microtomography dataset. The relationship between intrinsic tissue properties and apparent stiffness was explored. Moreover, the important role of collagen in bone micromechanics was demonstrated by complementing the study with Raman spectroscopy.

  11. The first metatarsal bone under loading conditions: a finite element analysis.

    Science.gov (United States)

    Kristen, K-H; Berger, K; Berger, C; Kampla, W; Anzböck, W; Weitzel, S H

    2005-03-01

    An individual-based, three-dimensional finite element model of the first metatarsal (MT I) bone was created with fine CT. The three-dimensional model of the bone was fixed proximally at the metatarsocuneiform joint and load was applied on the metatarsal head. Loading conditions were simulated, including muscular forces as described for a normal metatarsophalangeal (MTP) joint during three typical phases of gait as the combination of the load in the contact areas of the sesamoid bones and the base of the proximal phalanx. The resultant strain and stress distributions within the loaded MT I were calculated and visualized with the MTP in different positions.

  12. Application of FEM Analysis to Braced Excavation

    Institute of Scientific and Technical Information of China (English)

    LI Mingfei; Atsushi Nakamura; CAI Fei; Keizo Ugai

    2008-01-01

    It is becoming possible to do detailed numerical analyses for the various mechanical behavior of braced excavation by researching and developing the numerical analysis technique such as the finite ele-ment method (FEM).However,the mechanical behavior of braced excavation has not been clanfied fully both in theory and in expedence.Therefore,improving the prediction accuracy during the prior design is very important for making the observational method of braced excavation more effective.In this paper,FEM analyses were performed for a model of braced excavation by using Geotechnical Finite Element Elasto-plastic Analysis Software,GeoFEAS (2D).As the constitutive law of ground,MC-DP model, and Dun-can-Chang model were applied.The results were compared and discussed with that of a site measurement,and the effects of the constitutive law of ground on the analyzed result were verified.For the difference be-tween the results,the reason was investigated by the analyses adjusting the elastic modulus of ground,and the appropriate application of the constitutive law was researched.

  13. Finite Element Analysis of the Anti-radiation Excavator Cockpit Supporting Pedestal Based on Workbench%基于Workbench的防辐射挖掘机驾驶舱支座的有限元分析

    Institute of Scientific and Technical Information of China (English)

    任勇; 陈桂荣; 邱长军; 邹树梁; 李林升; 周炬

    2014-01-01

    The radiation protection cockpit addied with the shielding layer gained 5 . 5 t more than the original weight,so it was necessary to analyse and check the strength of the supporting pedestal. The finite element analysis was proceeded for the radiation excavator cockpit supporting pedestal by using ANSYS Workbench, and the deformation and stress distribution of cockpit supporting pedestal were obtained. Then the structure of cockpit sup-porting pedestal was optimized by thickening the supporting plate and rotation platform baseplate. Finally,the modal analysis was conducted for the excavator rotation platform,and the inherent frequency and vibrational modes of the first ten orders of rotation platform were obtained. The modal analysis provided the effective way to design the strength of the sup-porting pedestal and reduce the vibration of the cockpit.%增加了屏蔽层的防辐射驾驶舱较之原来驾驶舱增重了5.5 t,有必要对其支座的强度进行分析与校核.本文应用ANSYS Workbench对防辐射挖掘机驾驶舱支座进行有限元分析,得到其应变和应力分布情况;采取支撑板和回转平台底板加厚等措施对驾驶舱支座进行结构优化.最后对挖掘机回转平台进行模态分析,得出回转平台前十阶的固有频率和振型.模态分析为支撑座的强度设计,减少驾驶舱的振动提供了理论依据.

  14. Environmental effects induced by excavation

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Based on 3D Biot's consolidation theory and nonlinear Duncan-Chang's model, a 3D FEM (finite element method) program is developed considering the coupling of groundwater seepage and soil skeleton deformation during excavation. The comparison between the analysis result considering the variation of water head difference and that without considering it shows that the porewater pressure distribution of the former is distinctly different from that of the latter and that the foundation pit deformations of the former are larger than those of the latter, so that the result without considering the variation of water head difference is unreliable. The distribution rules of soil horizontal and vertical displacements around the pit and excess porewater pressure are analyzed in detail in time and space, which is very significant for guiding underground engineering construction and ensuring environment safety around the pit.

  15. Finite Element Analysis for Prediction of Shear and Stress Concentration & Distribution in Femoral Bone

    Science.gov (United States)

    Suhendra, N.; Gustiono, D.; Nugroho, E. A.; Masmui; Yuliani, H.

    2017-02-01

    The effect of micromotion on the shear shielding and size of yielding region in the bone asperity in contact with metal of femoral stem was investigated. The main objective of this work was to gain an understanding of bone wear particleformation mechanism from the two-dimensional finite element model of cementless femoral stem type. To assess the influence of the parameters of interest, different friction coefficients and sliding distance (micromotion)were used in the numerical simulations. Results from the finite element analysis showed that the increase ofthe yielding region is strongly influenced by the rise in sliding distance (micromotion), which is related to the generation of bone wear particle formations. Finite element bone wearparticle formation model, based on strain discontinuities, was therefore proposed for further works. The results obtained in this study can lead to the development of an accurate finite element wearparticle formation mechanism model that would be of use in the assessment of an artificial implant performance and their development.

  16. Improving peri-prosthetic bone adaptation around cementless hip stems: A clinical and finite element study

    NARCIS (Netherlands)

    Broeke, ten R.H.M.; Tarala, M.; Arts, J.J.; Janssen, D.W.; Verdonschot, N.J.J.; Geesink, R.G.T.

    2014-01-01

    This study assessed whether the Symax™ implant, a modification of the Omnifit® stem (in terms of shape, proximal coating and distal surface treatment), would yield improved bone remodelling in a clinical DEXA study, and if these results could be predicted in a finite element (FE) simulation study.

  17. Improving peri-prosthetic bone adaptation around cementless hip stems: A clinical and finite element study

    NARCIS (Netherlands)

    Broeke, R.H. Ten; Tarala, M.; Arts, J.J.C.; Janssen, D.W.; Verdonschot, N.J.J.; Geesink, R.G.T.

    2014-01-01

    This study assessed whether the Symax implant, a modification of the Omnifit((R)) stem (in terms of shape, proximal coating and distal surface treatment), would yield improved bone remodelling in a clinical DEXA study, and if these results could be predicted in a finite element (FE) simulation study

  18. A multiscale modelling of bone ultrastructure elastic proprieties using finite elements simulation and neural network method.

    Science.gov (United States)

    Barkaoui, Abdelwahed; Tlili, Brahim; Vercher-Martínez, Ana; Hambli, Ridha

    2016-10-01

    Bone is a living material with a complex hierarchical structure which entails exceptional mechanical properties, including high fracture toughness, specific stiffness and strength. Bone tissue is essentially composed by two phases distributed in approximately 30-70%: an organic phase (mainly type I collagen and cells) and an inorganic phase (hydroxyapatite-HA-and water). The nanostructure of bone can be represented throughout three scale levels where different repetitive structural units or building blocks are found: at the first level, collagen molecules are arranged in a pentameric structure where mineral crystals grow in specific sites. This primary bone structure constitutes the mineralized collagen microfibril. A structural organization of inter-digitating microfibrils forms the mineralized collagen fibril which represents the second scale level. The third scale level corresponds to the mineralized collagen fibre which is composed by the binding of fibrils. The hierarchical nature of the bone tissue is largely responsible of their significant mechanical properties; consequently, this is a current outstanding research topic. Scarce works in literature correlates the elastic properties in the three scale levels at the bone nanoscale. The main goal of this work is to estimate the elastic properties of the bone tissue in a multiscale approach including a sensitivity analysis of the elastic behaviour at each length scale. This proposal is achieved by means of a novel hybrid multiscale modelling that involves neural network (NN) computations and finite elements method (FEM) analysis. The elastic properties are estimated using a neural network simulation that previously has been trained with the database results of the finite element models. In the results of this work, parametric analysis and averaged elastic constants for each length scale are provided. Likewise, the influence of the elastic constants of the tissue constituents is also depicted. Results highlight

  19. 湖北沙市周梁玉桥遗址1987年的发掘%1987 Excavation on the Zhouliangyuqiao Site in Shashi, Hubei

    Institute of Scientific and Technical Information of China (English)

    荆州市周梁玉桥遗址博物馆

    2004-01-01

    This site lies in the northeastern part of Shashi District proper in Jingzhou City, Hubei Province. It has been excavated five times. In 1987, excavation was carried out in Area C, covering 104 sq m. The finds include six ash-pits, distinctive pottery, as well as bronzes, oracle shells with strong chronological features, stone implements, bone objects and antler artifacts. The cultural contents of the site feature the pottery composition in that sandy ware constitutes the main body, reddish-brown vessels form the largest proportion and the check patterns occur most frequently. These show that the site represents a Shang cultural complex with the local cultural elements playing the leading role. The excavation provided new data for the periodization of the site.

  20. Excavating the Role of Aloe Vera Wrapped Mesoporous Hydroxyapatite Frame Ornamentation in Newly Architectured Polyurethane Scaffolds for Osteogenesis and Guided Bone Regeneration with Microbial Protection.

    Science.gov (United States)

    Selvakumar, M; Pawar, Harpreet Singh; Francis, Nimmy K; Das, Bodhisatwa; Dhara, Santanu; Chattopadhyay, Santanu

    2016-03-09

    Guided bone regeneration (GBR) scaffolds are unsuccessful in many clinical applications due to a high incidence of postoperative infection. The objective of this work is to fabricate GBR with an anti-infective electrospun scaffold by ornamenting segmented polyurethane (SPU) with two-dimensional Aloe vera wrapped mesoporous hydroxyapatite (Al-mHA) nanorods. The antimicrobial characteristic of the scaffold has been retrieved from the prepared Al-mHA frame with high aspect ratio (∼14.2) via biosynthesis route using Aloe vera (Aloe barbadensis miller) extract. The Al-mHA frame was introduced into an unprecedented SPU matrix (solution polymerized) based on combinatorial soft segments of poly(ε-caprolactone) (PCL), poly(ethylene carbonate) (PEC), and poly(dimethylsiloxane) (PDMS), by an in situ technique followed by electrospinning to fabricate scaffolds. For comparison, pristine mHA nanorods are also ornamented into it. An enzymatic ring-opening polymerization technique was adapted to synthesize soft segment of (PCL-PEC-b-PDMS). Structure elucidation of the synthesized polymers is established by nuclear magnetic resonance spectroscopy. Sparingly, Al-mHA ornamented scaffolds exhibit tremendous improvement (175%) in the mechanical properties with promising antimicrobial activity against various human pathogens. After confirmation of high osteoconductivity, improved biodegradation, and excellent biocompatibility against osteoblast-like MG63 cells (in vitro), the scaffolds were implanted in rabbits as an animal model by subcutaneous and intraosseous (tibial) sites. Improved in vivo biocompatibilities, biodegradation, osteoconductivity, and the ability to provide an adequate biomimetic environment for biomineralization for GBR of the scaffolds (SPU and ornamented SPUs) have been found from the various histological sections. Early cartilage formation, endochondral ossification, and rapid bone healing at 4 weeks were found in the defects filled with Al-mHA ornamented

  1. The availability of bone powder as inorganic element source on growth and development in wheat seedlings.

    Science.gov (United States)

    Genisel, Mucip; Erdal, Serkan; Turk, Hulya; Dumlupinar, Rahmi

    2012-06-01

    Bone powder (BP), a by-product of cattle slaughtering plants, consists of fat, protein, amino acids, inorganic elements and vitamins. It is used as bone meal in biomedical and feed industry because of its rich content. In addition, bone contains a large amount of inorganic elements especially calcium (Ca) and phosphorus (P), which the plants need to maintain their physiological and biochemical processes. BP has been used as Ca and P source in agriculture for many years; however, its effects on plant growth and development have not yet been studied in detail. The present study aimed to determine the effects of BP on dry weight and contents of total chlorophyll, soluble protein and sugar as indicators of physiological response in the leaves. For this purpose, bone powder solutions (BPS) were prepared at different concentrations (0.5%, 1%, 1.5% and 2%) and applied to growing media of the 10-day wheat seedlings. Afterward, the 14-day seedlings were harvested, and the effects of BPS on plant response were determined. The results showed that BPS treatments significantly stimulated dry weight and contents of total chlorophyll, protein and sugar compared to control seedlings. The best stimulatory effect of BPS was determined at 1% concentration. According to these results, it is possible to say that BP may be used to meet the inorganic element requirements of plants in poor soils and hydroponic systems.

  2. Smooth surface micro finite element modelling of a cancellous bone analogue material.

    Science.gov (United States)

    Leung, S Y; Browne, M; New, A M

    2008-01-01

    Tetrahedral finite element meshes with smooth surfaces can be created from computed tomography scans of cancellous bone in order to evaluate its mechanical properties. Image processing before creation of the mesh can affect the accuracy of determined mechanical properties. For a cancellous bone analogue, threshold, mesh density and surface smoothing parameters used in mesh generation were varied and the mechanical properties predicted by the resulting meshes were compared to experimental results. This study has shown that threshold selection is vital for accurate determination of volume fraction and resulting mechanical properties.

  3. Finite element analysis on influence of implant surface treatments, connection and bone types.

    Science.gov (United States)

    Santiago Junior, Joel Ferreira; Verri, Fellippo Ramos; Almeida, Daniel Augusto de Faria; de Souza Batista, Victor Eduardo; Lemos, Cleidiel Aparecido Araujo; Pellizzer, Eduardo Piza

    2016-06-01

    The aim of this study is to assess the effect of different dental implant designs, bone type, loading, and surface treatment on the stress distribution around the implant by using the 3D finite-element method. Twelve 3D models were developed with Invesalius 3.0, Rhinoceros 4.0, and Solidworks 2010 software. The analysis was processed using the FEMAP 10.2 and NeiNastran 10.0 software. The applied oblique forces were 200 N and 100 N. The results were analyzed using maps of maximum principal stress and bone microstrain. Statistical analysis was performed using ANOVA and Tukey's test. The results showed that the Morse taper design was most efficient in terms of its distribution of stresses (p0.05). The different bone types did not show a significant difference in the stress/strain distribution (p>0.05). The surface treatment increased areas of stress concentration under axial loading (p<0.05) and increased areas of microstrain under axial and oblique loading (p<0.05) on the cortical bone. The Morse taper design behaved better biomechanically in relation to the bone tissue. The treated surface increased areas of stress and strain on the cortical bone tissue.

  4. 大型地下洞室群开挖支护弹塑性损伤优化研究%Study of support optimization of large underground cavern group excavation using elastoplastic damage finite elements

    Institute of Scientific and Technical Information of China (English)

    岳晓蕾; 王汉鹏; 郑学芬; 史向荣

    2011-01-01

    正在设计施工的某大型水电站地下洞室群地质条件复杂,其开挖支护方案对围岩稳定性非常重要,因此,对支护方案进行优化研究非常必要.为更真实地模拟岩体的力学特性,研究施工过程中岩体的损伤破坏,根据不可逆热力学理论建立了弹塑性损伤模型和损伤演化方程,并编制了三维弹塑性损伤有限元程序D-FEM,具有模拟开挖与支护、计算速度快、群组功能等特点.建立大型地下洞室群三维数值模型,将通过实测地应力反演的应力作为初始地应力.采用D-FEM模拟了不同支护方案洞室群的施工过程,通过分析洞室围岩的应力、位移和破损区,支护方案2的支护效果最好,建议采用此方案.考虑岩体损伤演化后与FLAC3D塑性区相比,洞室群边墙中部的破损区显著增加,因此,程序可应用于地下工程的稳定性分析.%The geological conditions of large underground cavem group are complicated, of which the support project affects stability of surrounding rock So it is important to study the support optimization of large underground cavem group excavation.In order to simulate rock mass veritably and analyze its damage in construction the elastoplastic damage model and damage evolution equation are presented on the basis of the irreversible thermodynamics theory.The 3D elastoplastic damage finite element code D-FEM is programmed by using Fortan language.which has the capabilities of simulating excavation and support.computing quickly and group function.3D numerical model of underground cavern group is established, input initial geostress is inversion of field stress measurement.The cavern group excavation by different support projects is simulated by D-FEM.The stress, displacement and damage of surrounding rock under three different cases are analyzed.The effect of No.2 support project is best and so is proposed Considering damage evolvement, damage zones compared to plastic zones of FLAC3D

  5. Safety excavation; Seguranca em escavacoes

    Energy Technology Data Exchange (ETDEWEB)

    Ribeiro, Walter Manoel [TRANSPETRO - PETROBRAS Transporte S.A., Rio de Janeiro, RJ (Brazil)

    2003-07-01

    In the construction and maintenance services of buried pipelines, the excavation is the activity that contains larger risk, could cause serious accidents. Norms, procedures and technical articles, national and international goods, should be followed for legal and technical aspects. This paper - Safety in Excavations - has purpose to gather all the technical concepts and of safety in a document denominated Procedure of Safety Excavation, serving as instrument to systematize and control the execution of excavation services in construction civil, assembly and pipelines repairs, seeking the people, facilities and the environment's safety. (author)

  6. Voxel-based approach to generate entire human metacarpal bone with microscopic architecture for finite element analysis.

    Science.gov (United States)

    Tang, C Y; Tsui, C P; Tang, Y M; Wei, L; Wong, C T; Lam, K W; Ip, W Y; Lu, W W J; Pang, M Y C

    2014-01-01

    With the development of micro-computed tomography (micro-CT) technology, it is possible to construct three-dimensional (3D) models of human bone without destruction of samples and predict mechanical behavior of bone using finite element analysis (FEA). However, due to large number of elements required for constructing the FE models of entire bone, this demands a substantial computational effort and the analysis usually needs a high level of computer. In this article, a voxel-based approach for generation of FE models of entire bone with microscopic architecture from micro-CT image data is proposed. To enable the FE analyses of entire bone to be run even on a general personal computer, grayscale intensity thresholds were adopted to reduce the amount of elements. Human metacarpal bone (MCP) bone was used as an example for demonstrating the applicability of the proposed method. The micro-CT images of the MCP bone were combined and converted into 3D array of pixels. Dual grayscale intensity threshold parameters were used to distinguish the pixels of bone tissues from those of surrounding soft tissues and improve predictive accuracy for the FE analyses with different sizes of elements. The method of selecting an appropriate value of the second grayscale intensity threshold was also suggested to minimize the area error for the reconstructed cross-sections of a FE structure. Experimental results showed that the entire FE MCP bone with microscopic architecture could be modeled and analyzed on a personal computer with reasonable accuracy.

  7. Concentration of key elements in North American meat and bone meal

    Energy Technology Data Exchange (ETDEWEB)

    Garcia, Rafael A. [USDA-ARS, Eastern Regional Research Center, Fats, Oils and Animal Coproducts Research Unit, 600 E. Mermaid Lane Wyndmoor, PA 19038 (United States); Rosentrater, Kurt A. [USDA-ARS, North Central Agricultural Research Laboratory, Integrated Cropping Systems Research Unit, 2923 Medary Avenue, Brookings, SD 57006 (United States)

    2008-09-15

    Meat and bone meal (MBM) and related rendered protein commodities have potential for use in applications other than animal feed, including use as a fuel or a phosphorus fertilizer. In order to develop these applications, data on the elemental composition are required; the currently available elemental composition data have important limitations. To generate more appropriate and reliable data, MBM samples were collected from 17 North American rendering plants, carefully prepared and analyzed for 20 elements. Preliminary studies showed that the sample preparation process artificially increased levels of sulfur and nickel in a manner that was correctable. Concentrations of many elements were found to agree with previously published values, but concentrations of potassium, magnesium and copper were significantly different from the most authoritative reference. Concentrations of heavy metals tested for were low, and arsenic and cadmium were not detected in any sample. Among the elements tested, there were a number of pairs of elements whose concentration was correlated with high significance, which in some cases was due to the varying proportions of soft tissue and bone in the MBM. The data presented should allow the development of non-feed applications for MBM to proceed with increased confidence. (author)

  8. Excavation damaged zone

    Energy Technology Data Exchange (ETDEWEB)

    Poulain, S.; Sergeant, C.; Vesvres, M.H.; Simonoff, M.; Lavielle, B.; Thomas, B.; Gilabert, E. [Bordeaux-1 Univ., I and 2/CNRS and GdR FORPRO 0788, Nuclear Analytical and Bioenvironmental Chemistry 33 - Gradignan (France); Poulain, S.; Altmann, S.; Lenoir, N.; Barnichon, J.D.; Wileveau, Y.; Lebon, P. [ANDRA - Agence Nationale pour la Gestion des Dechets Radioactifs, 92 - Chatenay Malabry (France); Le Marrec, C. [Bordeaux-1 Univ., ISTAB, INRA, UMR Oenologie - ISVV, 33 - Talence (France); Vinsot, A.; Dewonck, S.; Wileveau, Y.; Armand, G.; Cruchaudet, P.; Rebours, H.; Morel, J. [Agence Nationale pour la Gestion des Dechets Radioactifs, Lab. de Souterrain de Meuse/Haute-Marne, 55 - Bure (France); Lanyon, G.W. [Fracture Systems Ltd, Tregurrian, Ayr, St Ives, Cornwall (United Kingdom); Marschall, P.; Vietor, T. [NAGRA - National Cooperative for the Disposal of Radioactive Waste, Wettingen (Switzerland); Bourdeau, C.; Dedecker, F.; Billaux, D. [ITASCA Consultants, S.A.S., 69 - Ecully (France); Lenoir, N.; Desrues, J.; Viggiani, G.; Besuelle, P. [Laboratoire 3S-R - Sols Solides Structures-Risques, 38 - Grenoble (France); Bornert, M. [Ecole Polytechnique, LMS - Lab. de Mecanique des Solides, 91 - Palaiseau (France); Arson, C.; Gatmiri, B. [CERMES, Ecole Nationale des Ponts et Chaussees, 77 - Marne-la-Vallee (France); Gatmiri, B. [University of Tehran (Iran, Islamic Republic of); Bernier, F. [ESV EURIDICE GIE - European Underground Research Infrastructure for Disposal of Nuclear Waste in Clay Environment (Belgium); Nussbaum, C.; Mori, O. [Geotechnical Institute Ltd., Fabrique de Chaux, St-Ursanne (Switzerland); Bossart, P. [Swisstopo - Federal Office of Topography, Wabern (Switzerland); Schuster, K.; Alheid, H.J. [BGR - Bundesanstalt fur Geowissenschaften und Rohstoffe, Hannover (Germany); Lavanchy, J.M.; Croise, J.; Schwarz, R. [Colenco Power Engineering AG, Groundwater Protection and Waste Disposal, Baden (Switzerland)] [and others

    2007-07-01

    This session gathers 13 articles dealing with: autochthonous and colonizing microorganisms in argillaceous underground environments (S. Poulain, C. Sergeant, C. Le Marrec, M.H. Vesvres, A. Vinsot, S. Dewonck, M. Simonoff, S. Altmann); the discrete fracture network modelling of the Hg-a experiment at the Mont Terri rock Laboratory (G.W. Lanyon, P. Marschall, T. Vietor); the discrete modelling of drift behaviour in the Meuse/Haute-Marne URL, France (C. Bourdeau, F. Dedecker, D. Billaux); the fracturing in Callovo-Oxfordian argillite under triaxial compression studied by X-ray microtomography (N. Lenoir, J. Desrues, G. Viggiani, P. Besuelle, M. Bornert, J.D. Barnichon); a general review of the damage models for the EDZ creation (C. Arson, B. Gatmiri); similarities in the Hydro-Mechanical response of Callovo-Oxfordian clay and Boom clay during gallery excavation (Y. Wileveau, F. Bernier); the different geometries of the EDZ fracture networks in the Mont Terri and Meuse/Haute-Marne rock laboratories: Structural approach (C. Nussbaum, Y. Wileveau, P. Bossart, A. Moeri, G. Armand); the characterisation of the Excavation-Damaged Zone in the Meuse/Haute-Marne Underground Research Laboratory (G. Armand, P. Lebon, M. Cruchaudet, H. Rebours, J. Morel, Y. Wileveau); the EDZ characterisation with ultrasonic interval velocity measurements in the Meuse/Haute-Marne URL, performed between depth of 85 m and 504 m (K. Schuster, H.J. Alheid); the clay formation at the Meuse Haute Marne URL: evaluation of the impact of resin filled slots on flow paths characteristics within the EDZ (J.M. Lavanchy, J. Croise, R. Schwarz, G. Armand, M. Cruchaudet); the characterisation and evolution of EDZ by extraction and analyse of noble gases in pore waters in the Meuse/Haute Marne URL site (B. Lavielle, B. Thomas, E. Gilabert); in-situ gas test for the characterisation of Excavation Disturbed Zone at the Meuse/Haute Marne URL (H. Shao, K. Schuster, J. Soennke, V. Braeuer); and the flow and reactive

  9. Mixed-mode loading of the cement-bone interface: a finite element study.

    Science.gov (United States)

    Waanders, Daan; Janssen, Dennis; Bertoldi, Katia; Mann, Kenneth A; Verdonschot, Nico

    2011-02-01

    While including the cement-bone interface of complete cemented hip reconstructions is crucial to correctly capture their response, its modelling is often overly simplified. In this study, the mechanical mixed-mode response of the cement-bone interface is investigated, taking into account the effects of the well-defined microstructure that characterises the interface. Computed tomography-based plain strain finite element analyses models of the cement-bone interface are built and loaded in multiple directions. Periodic boundaries are considered and the failure of the cement and bone fractions by cracking of the bulk components are included. The results compare favourably with experimental observations. Surprisingly, the analyses reveal that under shear loading no failure occurs and considerable normal compression is generated to prevent interface dilation. Reaction forces, crack patterns and stress fields provide more insight into the mixed-mode failure process. Moreover, the cement-bone interface analyses provide details which can serve as a basis for the development of a cohesive law.

  10. Visualizing fossilization using laser ablation-inductively coupled plasma-mass spectrometry maps of trace elements in Late Cretaceous bones

    Science.gov (United States)

    Koenig, A.E.; Rogers, R.R.; Trueman, C.N.

    2009-01-01

    Elemental maps generated by laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) provide a previously unavailable high-resolution visualization of the complex physicochemical conditions operating within individual bones during the early stages of diagenesis and fossilization. A selection of LA-ICP-MS maps of bones collected from the Late Cretaceous of Montana (United States) and Madagascar graphically illustrate diverse paths to recrystallization, and reveal unique insights into geochemical aspects of taphonomic history. Some bones show distinct gradients in concentrations of rare earth elements and uranium, with highest concentrations at external bone margins. Others exhibit more intricate patterns of trace element uptake related to bone histology and its control on the flow paths of pore waters. Patterns of element uptake as revealed by LA-ICP-MS maps can be used to guide sampling strategies, and call into question previous studies that hinge upon localized bulk samples of fossilized bone tissue. LA-ICP-MS maps also allow for comparison of recrystallization rates among fossil bones, and afford a novel approach to identifying bones or regions of bones potentially suitable for extracting intact biogeochemical signals. ?? 2009 Geological Society of America.

  11. Micro-finite element simulation of trabecular-bone post-yield behaviour--effects of material model, element size and type.

    Science.gov (United States)

    Verhulp, E; Van Rietbergen, B; Muller, R; Huiskes, R

    2008-08-01

    Micro-finite element (micro-FE) analysis became a standard tool for the evaluation of trabecular bone mechanical properties. The accuracy of micro-FE models for linear analyses is well established. However, the accuracy of recently developed nonlinear micro-FE models for simulations of trabecular bone failure is not known. In this study, a trabecular bone specimen was compressed beyond the apparent yield point. The experiment was simulated using different micro-FE meshes with different element sizes and types, and material models based on cortical bone. The results from the simulations were compared with experimental results to study the effects of the different element and material models. It was found that a decrease in element size from 80 to 40 mum had little effect on predicted post-yield behaviour. Element type and material model had significant effects. Nevertheless, none of the established material models for cortical bone were able to predict the typical descent in the load-displacement curve seen during compression of trabecular bone.

  12. Selected aspects of designing deep excavations

    Directory of Open Access Journals (Sweden)

    Obrzud Rafał F.

    2016-09-01

    Full Text Available This paper analyzes two approaches to serviceability limit state (SLS verification for the deep excavation boundary value problem. The verification is carried out by means of the finite element (FE method with the aid of the commercial program ZSoil v2014. In numerical simulations, deep excavation in non-cohesive soil is supported with a diaphragm wall. In the first approach, the diaphragm wall is modeled with the Hookean material assuming reduced average stiffness and possible concrete cracking. The second approach is divided into two stages. In the first stage, the wall is modeled by defining its stiffness with the highest nominal Young’s modulus. The modulus makes it possible to find design bending moments which are used to compute the minimal design cross-section reinforcement for the retaining structure. The computed reinforcement is then used in a non-linear structural analysis which is viewed as the “actual” SLS verification.

  13. Evaluation of the parameters affecting bone temperature during drilling using a three-dimensional dynamic elastoplastic finite element model.

    Science.gov (United States)

    Chen, Yung-Chuan; Tu, Yuan-Kun; Zhuang, Jun-Yan; Tsai, Yi-Jung; Yen, Cheng-Yo; Hsiao, Chih-Kun

    2017-03-28

    A three-dimensional dynamic elastoplastic finite element model was constructed and experimentally validated and was used to investigate the parameters which influence bone temperature during drilling, including the drill speed, feeding force, drill bit diameter, and bone density. Results showed the proposed three-dimensional dynamic elastoplastic finite element model can effectively simulate the temperature elevation during bone drilling. The bone temperature rise decreased with an increase in feeding force and drill speed, however, increased with the diameter of drill bit or bone density. The temperature distribution is significantly affected by the drilling duration; a lower drilling speed reduced the exposure duration, decreases the region of the thermally affected zone. The constructed model could be applied for analyzing the influence parameters during bone drilling to reduce the risk of thermal necrosis. It may provide important information for the design of drill bits and surgical drilling powers.

  14. [Application of elemental microanalysis for estimation of osteoinduction and osteoconduction of hydroxyapatite bone implants].

    Science.gov (United States)

    Dawidowicz, Aleksander; Pielka, Stanisław; Paluch, Danuta; Kuryszko, Jan; Staniszewska-Kuś, Jolanta; Solski, Leszek

    2005-01-01

    Hydroxyapatite (HAp) ceramics based on calcium phosphates, chemical compounds being natural constructive element of bones is now regarded to be one of better implantation materials in osseous surgery and stomatology. HAp is poorly soluble and slowly resorbing in tissues material. Easiness of connecting of hydroxyapatite ceramics with other materials creates possibilities to produce new composites of chemical compounds containing calcium and easier resorbing. An important and till now not fully known problem is influence of hydrodroxyapatite grafts on the processes leading to production of calcium and phosphorus ions responsive for mineralization of bone tissue around the graft. Proliferation of osteoblasts and rate of osseous trabeculas production depends, among others, concentration of calcium and phosphorus ions. The main target of this study was the comparative analysis of the bone mineralisation rate after implantation of hydroxyapatite (HAp) and composites hydroxyapatite + beta tricalcium phosphate (HAp + TCP) and hydroxyapatite + calcium hydrosulfate (HAp + gypsum), on the basis of elemental microanalysis. Implantation studies were carried out on 24 rabbits. Sections were carried out 5, 9, 11 and 14 weeks after implantation of the tested materials. The carried out punctual analysis of the occurring elements and their topographic location (mapping) in bones after implantation showed essential differences among the tested grafts. Those differences were most significant after 5 and 14 weeks and depended on the rate of the tested materials resorption. On the basis of conducted macroscopic evaluation and scanning microscope assessment we can stated that the composite of HAp+TCP showed the best osteocunductive properties, while the best osteoinductive influence was shown by the composite HAp + gypsum.

  15. Individual-specific multi-scale finite element simulation of cortical bone of human proximal femur

    Energy Technology Data Exchange (ETDEWEB)

    Ascenzi, Maria-Grazia, E-mail: mgascenzi@mednet.ucla.edu [UCLA/Orthopaedic Hospital, Department of Orthopaedic Surgery, Rehabilitation Bldg, Room 22-69, 1000 Veteran Avenue, University of California, Los Angeles, CA 90095 (United States); Kawas, Neal P., E-mail: nealkawas@ucla.edu [UCLA/Orthopaedic Hospital, Department of Orthopaedic Surgery, Rehabilitation Bldg, Room 22-69, 1000 Veteran Avenue, University of California, Los Angeles, CA 90095 (United States); Lutz, Andre, E-mail: andre.lutz@hotmail.de [Institute of Biomechanics and Numerical Mechanics, Leibniz University Hannover, 30167 Hannover (Germany); Kardas, Dieter, E-mail: kardas@ibnm.uni-hannover.de [ContiTech Vibration Control, Jaedekamp 30 None, 30419 Hannover (Germany); Nackenhorst, Udo, E-mail: nackenhorst@ibnm.uni-hannover.de [Institute of Biomechanics and Numerical Mechanics, Leibniz University Hannover, 30167 Hannover (Germany); Keyak, Joyce H., E-mail: jhkeyak@uci.edu [Department of Radiological Sciences, Medical Sciences I, Bldg 811, Room B140, University of California, Irvine, CA 92697-5000 (United States)

    2013-07-01

    We present an innovative method to perform multi-scale finite element analyses of the cortical component of the femur using the individual’s (1) computed tomography scan; and (2) a bone specimen obtained in conjunction with orthopedic surgery. The method enables study of micro-structural characteristics regulating strains and stresses under physiological loading conditions. The analysis of the micro-structural scenarios that cause variation of strain and stress is the first step in understanding the elevated strains and stresses in bone tissue, which are indicative of higher likelihood of micro-crack formation in bone, implicated in consequent remodeling or macroscopic bone fracture. Evidence that micro-structure varies with clinical history and contributes in significant, but poorly understood, ways to bone function, motivates the method’s development, as does need for software tools to investigate relationships between macroscopic loading and micro-structure. Three applications – varying region of interest, bone mineral density, and orientation of collagen type I, illustrate the method. We show, in comparison between physiological loading and simple compression of a patient’s femur, that strains computed at the multi-scale model’s micro-level: (i) differ; and (ii) depend on local collagen-apatite orientation and degree of calcification. Our findings confirm the strain concentration role of osteocyte lacunae, important for mechano-transduction. We hypothesize occurrence of micro-crack formation, leading either to remodeling or macroscopic fracture, when the computed strains exceed the elastic range observed in micro-structural testing.

  16. Numerical analyses of influence of overlying pit excavation on existing tunnels

    Institute of Scientific and Technical Information of China (English)

    郑刚; 魏少伟

    2008-01-01

    The response of existing tunnel due to overlying excavation was studied using 2D FEM (Finite element method). Three typical locations of tunnel with respect to excavation, namely at the central line under the excavation bottom, directly under the base of diaphragm wall and outside of diaphragm, were considered. The variation of tunnel response with the change of location of tunnel was analyzed. The stress path of soil surrounding tunnel during the process of excavation was compared. Numerical analysis results indicate that the underlying tunnels at different locations under the excavation will experience convergence and divergence due to overlying excavation. Moreover, the tunnel located below base of diaphragm wall will experience distortion. The deformation is mainly due to the uneven changes of ground contact pressure on tunnel linings. Both the vertical and horizontal displacement of the tunnel decrease with the increase of the tunnel embedded depth beneath the formation of excavation.

  17. In vivo bone strain and finite element modeling of the mandible of Alligator mississippiensis

    Science.gov (United States)

    Porro, Laura B; Metzger, Keith A; Iriarte-Diaz, Jose; Ross, Callum F

    2013-01-01

    Forces experienced during feeding are thought to strongly influence the morphology of the vertebrate mandible; in vivo strain data are the most direct evidence for deformation of the mandible induced by these loading regimes. Although many studies have documented bone strains in the mammalian mandible, no information is available on strain magnitudes, orientations or patterns in the sauropsid lower jaw during feeding. Furthermore, strain gage experiments record the mechanical response of bone at a few locations, not across the entire mandible. In this paper, we present bone strain data recorded at various sites on the lower jaw of Alligator mississippiensis during in vivo feeding experiments. These data are used to understand how changes in loading regime associated with changes in bite location are related to changes in strain regime on the working and balancing sides of the mandible. Our results suggest that the working side mandible is bent dorsoventrally and twisted about its long-axis during biting, and the balancing side experiences primarily dorsoventral bending. Strain orientations are more variable on the working side than on the balancing side with changes in bite point and between experiments; the balancing side exhibits higher strain magnitudes. In the second part of this paper, we use principal strain orientations and magnitudes recorded in vivo to evaluate a finite element model of the alligator mandible. Our comparison demonstrates that strain orientations and mandibular deformation predicted by the model closely match in vivo results; however, absolute strain magnitudes are lower in the finite element model. PMID:23855772

  18. Biomechanical evaluation of dental implants in D1 and D4 bone by Finite Element Analysis.

    Science.gov (United States)

    Danza, M; Quaranta, A; Carinci, F; Paracchini, L; Pompa, G; Vozza, I

    2010-06-01

    The aim of the present study was to analyze stress and strain distribution in dental implants with different abutment's inclination inserted in D1 and D4 bone. The biomechanical behavior of 5 mm x 16 mm dental implants with straight, 15 degrees and 25 degrees angulated abutments subjected to static loads, in contact with D1 and D4 bone, was evaluated by Finite Element Analysis (FEA). The lowest stress and strain values were found in the system composed by implants with straight abutments loaded with a 200-N vertical strength, while the highest stress and strain values were found in implants with 15 degrees angulated abutment loaded with a tilted strength (FY=200 N and FZ=140 N). Stress value increased from D1 to D4 bone, while strain value decreased due to the effect of normal elasticity mode of biological tissues. The different stress and strain distribution in D1 and D4 bone tissue surrounding dental implants with a tapered neck could favor prosthetic load and play a role in implant long-term success.

  19. Reducing-resistance mechanism of vibratory excavation of hydraulic excavator

    Institute of Scientific and Technical Information of China (English)

    ZHU Jian-xin; YANG Cheng-yun; HU Huo-yan; ZOU Xiang-fu

    2008-01-01

    Based on the working principle of vibratory excavation of hydraulic excavator, the expression of digging resistance changed with time under sine wave inspiritment was deduced; a comparison analysis was given after calculating the forces status of rock and soil under static load and vibratory load respectively by using MATLAB; and then RFPA-2D(rock failure process analysis code) was used to make comparison of simulation experiment on rock and soil failure process under static load and vibratory load. The results demonstrate that, compared with the normal excavation under the same situation, the digging resistance and the energy consumption can be reduced by respectively 30% and 60% at maximum, and that the working efficiency can be increased by 45% at maximum owing to vibratory excavation.

  20. Three dimensional stereolithography models of cancellous bone structures from muCT data: testing and validation of finite element results.

    Science.gov (United States)

    Dobson, C A; Sisias, G; Phillips, R; Fagan, M J; Langton, C M

    2006-04-01

    Stereolithography (STL) models of complex cancellous bone structures have been produced from three-dimensional micro-computed tomography data sets of human cancellous bone histological samples from four skeletal sites. The STL models have been mechanically tested and the derived stiffness compared with that predicted by finite element analysis. The results show a strong correlation (R2 = 0.941) between the predicted and calculated stiffnesses of the structures and show promise for the use of STL as an additional technique to complement the use of finite element models, for the assessment of the mechanical properties of complex cancellous bone structures.

  1. Selected aspects of designing deep excavations

    Science.gov (United States)

    Obrzud, Rafał F.; Hartmann, Sébastien; Podleś, Krzysztof

    2016-09-01

    This paper analyzes two approaches to serviceability limit state (SLS) verification for the deep excavation boundary value problem. The verification is carried out by means of the finite element (FE) method with the aid of the commercial program ZSoil v2014. In numerical simulations, deep excavation in non-cohesive soil is supported with a diaphragm wall. In the first approach, the diaphragm wall is modeled with the Hookean material assuming reduced average stiffness and possible concrete cracking. The second approach is divided into two stages. In the first stage, the wall is modeled by defining its stiffness with the highest nominal Young's modulus. The modulus makes it possible to find design bending moments which are used to compute the minimal design cross-section reinforcement for the retaining structure. The computed reinforcement is then used in a non-linear structural analysis which is viewed as the "actual" SLS verification. In the second part, the paper examines the same boundary value problem assuming that the excavation takes place in quasi-impermeable cohesive soils, which are modeled with the Hardening Soil model. This example demonstrates the consequences of applying the steady-state type analysis for an intrinsically time-dependent problem. The results of this analysis are compared to the results from the consolidation-type analysis, which are considered as a reference. For both analysis types, the two-phase formulation for partially- saturated medium, after Aubry and Ozanam, is used to describe the interaction between the soil skeleton and pore water pressure.

  2. Astronaut Bone Medical Standards Derived from Finite Element (FE) Models of QCT Scans from Population Studies

    Science.gov (United States)

    Sibonga, J. D.; Feiveson, A. H.

    2014-01-01

    This work was accomplished in support of the Finite Element [FE] Strength Task Group, NASA Johnson Space Center [JSC], Houston, TX. This group was charged with the task of developing rules for using finite-element [FE] bone-strength measures to construct operating bands for bone health that are relevant to astronauts following exposure to spaceflight. FE modeling is a computational tool used by engineers to estimate the failure loads of complex structures. Recently, some engineers have used this tool to characterize the failure loads of the hip in population studies that also monitored fracture outcomes. A Directed Research Task was authorized in July, 2012 to investigate FE data from these population studies to derive these proposed standards of bone health as a function of age and gender. The proposed standards make use of an FE-based index that integrates multiple contributors to bone strength, an expanded evaluation that is critical after an astronaut is exposed to spaceflight. The current index of bone health used by NASA is the measurement of areal BMD. There was a concern voiced by a research and clinical advisory panel that the sole use of areal BMD would be insufficient to fully evaluate the effects of spaceflight on the hip. Hence, NASA may not have a full understanding of fracture risk, both during and after a mission, and may be poorly estimating in-flight countermeasure efficacy. The FE Strength Task Group - composed of principal investigators of the aforementioned population studies and of FE modelers -donated some of its population QCT data to estimate of hip bone strength by FE modeling for this specific purpose. Consequently, Human Health Countermeasures [HHC] has compiled a dataset of FE hip strengths, generated by a single FE modeling approach, from human subjects (approx.1060) with ages covering the age range of the astronauts. The dataset has been analyzed to generate a set of FE strength cutoffs for the following scenarios: a) Qualify an

  3. Mammoth (Mammuthus sp.) excavation on a college campus in Western Illinois, USA

    Science.gov (United States)

    Treworgy, J.D.; Saunders, J.J.; Grimley, D.A.

    2007-01-01

    The discovery of the remains of a mammoth, Mammuthus sp., on the Principia College campus in Elsah, Illinois, has allowed for careful excavation by students over several years. The mammoth is relatively well preserved in late Wisconsin Peoria Silt on the top of the bluffs of the Mississippi River. The mammoth was buried by loess, perhaps as a result of persistent dust storms, approximately 17 500 14C years ago. This age estimate is based on the mammoth's stratigraphic position within the Peoria Silt and is loosely supported by an AMS radiocarbon age on poorly preserved collagen from tooth dentine (???17 810??4300 14C years [CAMS #104172]). Over one hundred bones or bone pieces have been excavated to-date. The skull, containing the tusks and maxillary teeth, is complete and in close proximity to associated postcranial remains, indicating that the mammoth died where it was found. The size and characteristics of skeletal elements have allowed us to determine that this was a mature male of about 41 years of age. Taxonomic attribution-either to Mammuthus primigenius or Mammuthus jeffersonii-is pending, based on the outcome of thorough analysis once the skull with dentition has been prepared from enclosing matrix. ?? 2006 Elsevier Ltd and INQUA.

  4. Effects of Bone Young’s Modulus on Finite Element Analysis in the Lateral Ankle Biomechanics

    Directory of Open Access Journals (Sweden)

    W. X. Niu

    2013-01-01

    Full Text Available Finite element analysis (FEA is a powerful tool in biomechanics. The mechanical properties of biological tissue used in FEA modeling are mainly from experimental data, which vary greatly and are sometimes uncertain. The purpose of this study was to research how Young’s modulus affects the computations of a foot-ankle FEA model. A computer simulation and an in-vitro experiment were carried out to investigate the effects of incremental Young’s modulus of bone on the stress and strain outcomes in the computational simulation. A precise 3-dimensional finite element model was constructed based on an in-vitro specimen of human foot and ankle. Young’s moduli were assigned as four levels of 7.3, 14.6, 21.9 and 29.2 GPa respectively. The proximal tibia and fibula were completely limited to six degrees of freedom, and the ankle was loaded to inversion 10° and 20° through the calcaneus. Six cadaveric foot-ankle specimens were loaded as same as the finite element model, and strain was measured at two positions of the distal fibula. The bone stress was less affected by assignment of Young’s modulus. With increasing of Young’s modulus, the bone strain decreased linearly. Young’s modulus of 29.2 GPa was advisable to get the satisfactory surface strain results. In the future study, more ideal model should be constructed to represent the nonlinearity, anisotropy and inhomogeneity, as the same time to provide reasonable outputs of the interested parameters.

  5. Effects of Bone Young’s Modulus on Finite Element Analysis in the Lateral Ankle Biomechanics

    OpenAIRE

    Niu, W. X.; Wang, L J; Feng, T. N.; Jiang, C.H.; Fan, Y. B.; M. Zhang

    2013-01-01

    Finite element analysis (FEA) is a powerful tool in biomechanics. The mechanical properties of biological tissue used in FEA modeling are mainly from experimental data, which vary greatly and are sometimes uncertain. The purpose of this study was to research how Young’s modulus affects the computations of a foot-ankle FEA model. A computer simulation and an in-vitro experiment were carried out to investigate the effects of incremental Young’s modulus of bone on the stress and strain outcomes ...

  6. Bone stress for a mini-implant close to the roots of adjacent teeth--3D finite element analysis.

    Science.gov (United States)

    Motoyoshi, M; Ueno, S; Okazaki, K; Shimizu, N

    2009-04-01

    This study aimed to evaluate stress in the bone when an orthodontic mini-implant is close to the roots of adjacent teeth using finite element models (FEMs), and to investigate the causes of the high implant failure rate in the mandible. Four FEMs were used: the implant touches nothing; the implant touches the surface of the periodontal membrane; part of the screw thread is embedded in the periodontal membrane; and the implant touches the root. The effect of cortical bone thickness was evaluated using values of 1, 2 and 3 mm. Maximum stress value and stress distribution on the bone elements was determined. Maximum stress on the bone increased when the mini-implant was close to the root. When the implant touched the root, stress increased to 140 MPa or more, and bone resorption could be predicted. Stress was higher for a cortical bone thickness of 2 mm than for other thicknesses. Cortical bone 2 mm thick had a higher risk for bone resorption. A mandible with an average cortical bone thickness of 2 mm may have a higher risk for implant loosening than a maxilla with the same degree of root proximity, which may be related to the lower success rate in the mandible.

  7. cAMP-response-element-binding protein positively regulates breast cancer metastasis and subsequent bone destruction

    Energy Technology Data Exchange (ETDEWEB)

    Son, Jieun; Lee, Jong-Ho; Kim, Ha-Neui; Ha, Hyunil, E-mail: hyunil74@hotmail.com; Lee, Zang Hee, E-mail: zang1959@snu.ac.kr

    2010-07-23

    Research highlights: {yields} CREB is highly expressed in advanced breast cancer cells. {yields} Tumor-related factors such as TGF-{beta} further elevate CREB expression. {yields} CREB upregulation stimulates metastatic potential of breast cancer cells. {yields} CREB signaling is required for breast cancer-induced bone destruction. -- Abstract: cAMP-response-element-binding protein (CREB) signaling has been reported to be associated with cancer development and poor clinical outcome in various types of cancer. However, it remains to be elucidated whether CREB is involved in breast cancer development and osteotropism. Here, we found that metastatic MDA-MB-231 breast cancer cells exhibited higher CREB expression than did non-metastatic MCF-7 cells and that CREB expression was further increased by several soluble factors linked to cancer progression, such as IL-1, IGF-1, and TGF-{beta}. Using wild-type CREB and a dominant-negative form (K-CREB), we found that CREB signaling positively regulated the proliferation, migration, and invasion of MDA-MB-231 cells. In addition, K-CREB prevented MDA-MB-231 cell-induced osteolytic lesions in a mouse model of cancer metastasis. Furthermore, CREB signaling in cancer cells regulated the gene expression of PTHrP, MMPs, and OPG, which are closely involved in cancer metastasis and bone destruction. These results indicate that breast cancer cells acquire CREB overexpression during their development and that this CREB upregulation plays an important role in multiple steps of breast cancer bone metastasis.

  8. A theory for bone resorption based on the local rupture of osteocytes cells connections: A finite element study.

    Science.gov (United States)

    Ridha, Hambli; Almitani, Khalid H; Chamekh, Abdessalem; Toumi, Hechmi; Tavares, Joao Manuel R S

    2015-04-01

    In this work, a bone damage resorption finite element model based on the disruption of the inhibitory signal transmitted between osteocytes cells in bone due to damage accumulation is developed and discussed. A strain-based stimulus function coupled to a damage-dependent spatial function is proposed to represent the connection between two osteocytes embedded in the bone tissue. The signal is transmitted to the bone surface to activate bone resorption. The proposed model is based on the idea that the osteocyte signal reduction is not related to the reduction of the stimulus sensed locally by osteocytes due to damage, but to the difficulties for the signal in travelling along a disrupted area due to microcracks that can destroy connections of the intercellular network between osteocytes and bone-lining cells. To check the potential of the proposed model to predict the damage resorption process, two bone resorption mechano-regulation rules corresponding to two mechanotransduction approaches have been implemented and tested: (1) Bone resorption based on a coupled strain-damage stimulus function without ruptured osteocyte connections (NROC); and (2) Bone resorption based on a strain stimulus function with ruptured osteocyte connections (ROC). The comparison between the results obtained by both models, shows that the proposed model based on ruptured osteocytes connections predicts realistic results in conformity with previously published findings concerning the fatigue damage repair in bone.

  9. Micro-finite-element method to assess elastic properties of trabecular bone at micro- and macroscopic level.

    Science.gov (United States)

    Rieger, R; Auregan, J C; Hoc, T

    2017-09-08

    The objective of the present study is to assess the mechanical behavior of trabecular bone based on microCT imaging and micro-finite-element analysis. In this way two methods are detailed: (i) direct determination of macroscopic elastic property of trabecular bone; (ii) inverse approach to assess mechanical properties of trabecular bone tissue. Thirty-five females and seven males (forty-two subjects) mean aged (±SD) 80±11.7 years from hospitals of Assistance publique-Hôpitaux de Paris (AP-HP) diagnosed with osteoporosis following a femoral neck fracture due to a fall from standing were included in this study. Fractured heads were collected during hip replacement surgery. Standardized bone cores were removed from the femoral head's equator by a trephine in a water bath. MicroCT images acquisition and analysis were performed with CTan(®) software and bone volume fraction was then determined. Micro-finite-element simulations were per-formed using Abaqus 6.9-2(®) software in order to determine the macroscopic mechanical behaviour of the trabecular bone. After microCT acquisition, a longitudinal compression test was performed and the experimental macroscopic Young's Modulus was extracted. An inverse approach based on the whole trabecular bone's mechanical response and micro-finite-element analysis was performed to determine microscopic mechanical properties of trabecular bone. In the present study, elasticity of the tissue was shown to be similar to that of healthy tissue but with a lower yield stress. Classical histomorphometric analysis form microCT imaging associated with an inverse micro-finite-element method allowed to assess microscopic mechanical trabecular bone parameters. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

  10. Bone char surface modification by nano-gold coating for elemental mercury vapor removal

    Energy Technology Data Exchange (ETDEWEB)

    Assari, Mohamad javad [Department of Environmental & Occupational Health, Faculty of Medical Sciences, Tarbiat Modares university, Tehran (Iran, Islamic Republic of); Rezaee, Abbas, E-mail: rezaee@modares.ac.ir [Department of Environmental & Occupational Health, Faculty of Medical Sciences, Tarbiat Modares university, Tehran (Iran, Islamic Republic of); Rangkooy, Hossinali [Occupational Health Department, Faculty of Health, Jondishapor Medical Sciences University, Ahvaz (Iran, Islamic Republic of)

    2015-07-01

    Highlights: • A novel nanocomposite including bone char and gold nanoparticle was developed for capture of Hg{sup 0} vapor. • EDS and XRD results confirm the presence of nano-gold on the surface of the bone char support. • The majority of the pores were found to be in the mesoporous range. • The dynamic capacity of 586 μg/g was obtained for Hg{sup 0} vapor. - Abstract: The present work was done to develop a novel nanocomposite using bone char coated with nano-gold for capture of elemental mercury (Hg{sup 0}) from air. The morphologies, structures, and chemical constitute of the prepared nanocomposite were evaluated by UV–VIS–NIR, dynamic light-scattering (DLS), X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infra-red (FTIR) spectroscopy, and energy dispersive X-ray spectroscopy (EDS). The capture performance of nanocomposite was evaluated in a needle trap for mercury vapor. An on-line setup based on cold vapor atomic absorption spectrometry (CVAAS) was designed for Hg{sup 0} determination. Dynamic capacity of nanocomposite for Hg{sup 0} was shown high efficient operating capacity of 586.7 μg/g. As temperature increases, the dynamic adsorption capacity of the nanocomposite was decreased, which are characteristics of physicosorption processes. It was found that the surface modification of bone char with nano-gold has various advantages such as high operating dynamic adsorption capacity and low cost preparation. It was also demonstrated that the developed nanocomposite is suitable for on-line monitoring of Hg{sup 0}. It could be applied for the laboratory and field studies.

  11. Three-fin acetabular prosthesis for superior acetabular bone defects: a three-dimensional finite element analysis

    Institute of Scientific and Technical Information of China (English)

    LIU Yu-zeng; HAI Yong; ZHAO Hui

    2012-01-01

    Background Given that three-dimensional finite element models have been successfully used to analyze biomechanics in orthopedics-related research,this study aimed to establish a finite element model of the pelvic bone and three-fin acetabular component and evaluate biomechanical changes in this model after implantation of a three-fin acetabular prosthesis in a superior segmental bone defect of the acetabulum.Methods In this study,three-dimensional finite element models of the pelvic bone and three-fin acetabular component were first established.The prosthesis model was characterized by three different conformational fins to facilitate and optimize the prosthetic design.The spongy and cortical bones were evaluated using a different modulus of elasticity in this established model.Results The maximum and minimum von Mises stresses on the fins of the acetabular component were 15.2 and 0.74,respectively.The maximum and minimum micromotion between the three-fin acetabular component and the acetabulum bone interface were 27 and 13 μm,respectively.A high primary stability and implied better clinical outcome were revealed.Conclusion Finite element analysis may be an optimal strategy for biomechanics-related research of prosthetic design for segmental acetabular bone defects.

  12. Optimizing finite element predictions of local subchondral bone structural stiffness using neural network-derived density-modulus relationships for proximal tibial subchondral cortical and trabecular bone.

    Science.gov (United States)

    Nazemi, S Majid; Amini, Morteza; Kontulainen, Saija A; Milner, Jaques S; Holdsworth, David W; Masri, Bassam A; Wilson, David R; Johnston, James D

    2017-01-01

    Quantitative computed tomography based subject-specific finite element modeling has potential to clarify the role of subchondral bone alterations in knee osteoarthritis initiation, progression, and pain. However, it is unclear what density-modulus equation(s) should be applied with subchondral cortical and subchondral trabecular bone when constructing finite element models of the tibia. Using a novel approach applying neural networks, optimization, and back-calculation against in situ experimental testing results, the objective of this study was to identify subchondral-specific equations that optimized finite element predictions of local structural stiffness at the proximal tibial subchondral surface. Thirteen proximal tibial compartments were imaged via quantitative computed tomography. Imaged bone mineral density was converted to elastic moduli using multiple density-modulus equations (93 total variations) then mapped to corresponding finite element models. For each variation, root mean squared error was calculated between finite element prediction and in situ measured stiffness at 47 indentation sites. Resulting errors were used to train an artificial neural network, which provided an unlimited number of model variations, with corresponding error, for predicting stiffness at the subchondral bone surface. Nelder-Mead optimization was used to identify optimum density-modulus equations for predicting stiffness. Finite element modeling predicted 81% of experimental stiffness variance (with 10.5% error) using optimized equations for subchondral cortical and trabecular bone differentiated with a 0.5g/cm(3) density. In comparison with published density-modulus relationships, optimized equations offered improved predictions of local subchondral structural stiffness. Further research is needed with anisotropy inclusion, a smaller voxel size and de-blurring algorithms to improve predictions. Copyright © 2016 Elsevier Ltd. All rights reserved.

  13. Excavations at Cricklade, Wiltshire, 1975

    Directory of Open Access Journals (Sweden)

    Jeremy Haslam

    2003-07-01

    Full Text Available The town of Cricklade in Wiltshire, England is one of the most regular examples of the class of Saxon urban fortresses, created as part of a fort-system in the late 9th century, which are included in the Burghal Hidage List. Its defences are relatively well preserved, and show particularly good evidence of rectilinear planning. It has been the subject of detailed archaeological and historical research over the past 55 years, and its defences at least can lay claim to being the most systematically explored late Saxon fortress in England. Prior to housing development, two excavations were carried out at Cricklade in 1975: Site A, an area within the north-west quarter of the town, which provided evidence of occupation throughout the Roman period; and Site B, on the south-west corner of the late Saxon defences, in which several trenches as well as larger areas across the line of the defences were excavated. A sequence of several successive phases of construction, refurbishment, destruction and rebuilding of the defences from the late 9th century into the medieval period was found. The interpretation of this sequence of phases differs from that put forward based on earlier excavations on the defences since 1948 (excavations which are also reassessed here. Accompanied by interactive plans and sections, this article presents the results of the excavations, followed by an examination of the archaeological and historical development of the defensive sequence and early development of the town.

  14. The effect of zinc deficiency and zinc supplementation on element levels in the bone tissue of ovariectomized rats: histopathologic changes.

    Science.gov (United States)

    Baltaci, Abdulkerim Kasim; Sunar, Fusun; Mogulkoc, Rasim; Acar, Musa; Toy, Hatice

    2014-05-01

    Study aimed to determine the effects of zinc supplementation/deficiency on the histological structure and elements levels in bone tissue in ovariectomized rats. The study included 40 Sprague-Dawley type adult female rats, divided as follows: Control, ovariectomized, ovariectomized + zinc supplemented, ovariectomized + zinc deficient groups. At the end of the study bone tissues (femur) were collected to determine the levels of calcium, phosphorus, magnesium, zinc, iron, aluminium, chrome, lithium, lead, nickel, and manganese. The bone tissue was examined for histopathology. Ovariectomy leaded to significant decrease in magnesium. Zinc supplementation to ovariectomized rats restored the reduced calcium, phosphorus, zinc. However, zinc deficiency in ovariectomized rats further reduced calcium, phosphorus, zinc, and manganese levels. Zinc deficiency in ovariectomized significantly increased Al, Cr, Li, Pb, and Ni levels. Tissue integrity was impaired due to ovariectomy and zinc deficiency. Ovariectomy and zinc deficiency leads significant decreases elements of the bone.

  15. Comparison of patella bone strain between females with and without patellofemoral pain: a finite element analysis study.

    Science.gov (United States)

    Ho, Kai-Yu; Keyak, Joyce H; Powers, Christopher M

    2014-01-03

    Elevated bone principal strain (an indicator of potential bone injury) resulting from reduced cartilage thickness has been suggested to contribute to patellofemoral symptoms. However, research linking patella bone strain, articular cartilage thickness, and patellofemoral pain (PFP) remains limited. The primary purpose was to determine whether females with PFP exhibit elevated patella bone strain when compared to pain-free controls. A secondary objective was to determine the influence of patella cartilage thickness on patella bone strain. Ten females with PFP and 10 gender, age, and activity-matched pain-free controls participated. Patella bone strain fields were quantified utilizing subject-specific finite element (FE) models of the patellofemoral joint (PFJ). Input parameters for the FE model included (1) PFJ geometry, (2) elastic moduli of the patella bone, (3) weight-bearing PFJ kinematics, and (4) quadriceps muscle forces. Using quasi-static simulations, peak and average minimum principal strains as well as peak and average maximum principal strains were quantified. Cartilage thickness was quantified by computing the perpendicular distance between opposing voxels defining the cartilage edges on axial plane magnetic resonance images. Compared to the pain-free controls, individuals with PFP exhibited increased peak and average minimum and maximum principal strain magnitudes in the patella. Additionally, patella cartilage thickness was negatively associated with peak minimum principal patella strain and peak maximum principal patella strain. The elevated bone strain magnitudes resulting from reduced cartilage thickness may contribute to patellofemoral symptoms and bone injury in persons with PFP. © 2013 Published by Elsevier Ltd.

  16. Effects of dose reduction on bone strength prediction using finite element analysis

    Science.gov (United States)

    Anitha, D.; Subburaj, Karupppasamy; Mei, Kai; Kopp, Felix K.; Foehr, Peter; Noel, Peter B.; Kirschke, Jan S.; Baum, Thomas

    2016-12-01

    This study aimed to evaluate the effect of dose reduction, by means of tube exposure reduction, on bone strength prediction from finite-element (FE) analysis. Fresh thoracic mid-vertebrae specimens (n = 11) were imaged, using multi-detector computed tomography (MDCT), at different intensities of X-ray tube exposures (80, 150, 220 and 500 mAs). Bone mineral density (BMD) was estimated from the mid-slice of each specimen from MDCT images. Differences in image quality and geometry of each specimen were measured. FE analysis was performed on all specimens to predict fracture load. Paired t-tests were used to compare the results obtained, using the highest CT dose (500 mAs) as reference. Dose reduction had no significant impact on FE-predicted fracture loads, with significant correlations obtained with reference to 500 mAs, for 80 mAs (R2  = 0.997, p analysis. Reduced CT dose will enable early diagnosis and advanced monitoring of osteoporosis and associated fracture risk.

  17. Incorporation of Trace Elements in Ancient and Modern Human Bone: An X-Ray Absorption Spectroscopy Study

    Science.gov (United States)

    Pingitore, N. E.; Cruz-Jimenez, G.; Price, T. D.

    2001-12-01

    X-ray absorption spectroscopy (XAS) affords the opportunity to probe the atomic environment of trace elements in human bone. We are using XAS to investigate the mode(s) of incorporation of Sr, Zn, Pb, and Ba in both modern and ancient (and thus possibly altered) human and animal bone. Because burial and diagenesis may add trace elements to bone, we performed XAS analysis on samples of pristine contemporary and ancient, buried human and animal bone. We assume that deposition of these elements during burial occurs by processes distinct from those in vivo, and this will be reflected in their atomic environments. Archaeologists measure strontium in human and animal bone as a guide to diet. Carnivores show lower Sr/Ca ratios than their herbivore prey due to discrimination against Sr relative to Ca up the food chain. In an initial sample suite no difference was observed between modern and buried bone. Analysis of additional buried samples, using a more sensitive detector, revealed significant differences in the distance to the second and third neighbors of the Sr in some of the buried samples. Distances to the first neighbor, oxygen, were similar in all samples. Zinc is also used in paleo-diet studies. Initial x-ray absorption spectroscopy of a limited suite of bones did not reveal any differences between modern and buried samples. This may reflect the limited number of samples examined or the low levels of Zn in typical aqueous solutions in soils. Signals from barium and lead were too low to record useful XAS spectra. Additional samples will be studied for Zn, Ba, and Pb. We conducted our XAS experiments on beam lines 4-1 and 4-3 at the Stanford Synchrotron Radiation Laboratory. Data were collected in the fluorescence mode, using a Lytle detector and appropriate filter, and a solid state, 13-element Ge-detector.

  18. Remote Excavation System test plan

    Energy Technology Data Exchange (ETDEWEB)

    Walker, S.; Hyde, R.A.

    1993-05-01

    The Office of Technology Development (OTD) established the Robotics Technology Development Program (RTDP) to integrate robotic development activities on a national basis; provide needs-oriented, timely, and economical robotics technology to support environmental and waste operations activities at Department of Energy (DOE) sites; and provide the focus and direction for the near term (less than five years) and guidance for the tong-term (five to twenty years) research and development efforts for site-specific problems. The RTDP consists of several programs including the Buried Waste Robotics Program (BWRP), which addresses remote buried waste applications. The Remote Excavation System (RES) was developed under the RTDP to provide a safer method of excavating hazardous materials for both the DOE and the Department of Defense (DOD). The excavator, initially developed by the DOD as a manually-operated small excavator, has been modified for teleoperation with joint funding from the BWRP and the DOD. The Buried Waste Integrated Demonstration (BWID) and the Uranium Soils Integrated Demonstration (USID) are funding the demonstration, testing, and evaluation of the RES covered in this test plan. This document covers testing both at Oak Ridge National Laboratory (ORNL) and the Idaho National Engineering Laboratory (INEL), as funded by BWID and USID. This document describes the tests planned for the RES demonstration for the BWRP. The purposes of the test plan are (1) to establish test parameters to ensure that the demonstration results are deemed useful and usable and (2) to demonstrate performance in a safe manner within all regulatory requirements.

  19. Fish remnants from the excavations of the Bronze Age barrow near Maryanskoe village (Dnepropetrovsk region, Ukraine

    Directory of Open Access Journals (Sweden)

    O. M. Kovalchuk

    2014-10-01

    Full Text Available The Bronze Age mound (2.5–2.3 kya BC is located near the Maryanskoe village (Apostolovskyi district, Dnepropetrovsk region and was excavated in 1953. The results of determination of the fish remnants, which were found during the excavation, are presented in the paper. Eleven species belonging to 9 genera, 5 families and 5 orders (Acipenseriformes, Cypriniformes, Siluriformes, Esociformes, Perciformes were identified: russian sturgeon Acipenser gueldenstaedtii Brandt et Ratzeburg, 1833, stellate sturgeon A. stellatus Pallas, 1771, common ide Idus idus (Linnaeus, 1758, common roach Rutilus rutilus (Linnaeus, 1758, pontic roach R. frisii (Nordmann, 1840, common bream Abramis brama (Linnaeus, 1758, common carp Cyprinus carpio Linnaeus, 1758, tench Tinca tinca (Linnaeus, 1758, european catfish Silurus glanis Linnaeus, 1758, northern pike Esox lucius (Linnaeus, 1758, and zander Sander lucioperca (Linnaeus, 1758. Most of them are quite common in the Dnieper river basin. It was found that carp fishes predominate in the number of species. Most of the bone remnants in the collection belong to zander, catfish and pike, while common roach, pontic roach and common bream are identified by the few bones. This may indicate a different role of these species in the diet of the local population. The ratio of skeletal elements in the collection is the evidence of the fish cutting on the site. Body length and weight was reconstructed for 64 fish specimens. It was found that they were mature and small-sized, except for catfish, pike and perch. Taking into account the characteristics of the funeral rituals of the Yamna culture population, fish bones from the mound near Maryanskoe can be remnants of the parting meal.

  20. Low-energy Planetary Excavator (LPE) Project

    Data.gov (United States)

    National Aeronautics and Space Administration — ORBITEC proposes to develop an innovative Low-energy Planetary Excavator (LPE) to excavate in situ regolith, ice-regolith mixes, and a variety of other geologic...

  1. Low-energy Planetary Excavator (LPE) Project

    Data.gov (United States)

    National Aeronautics and Space Administration — ORBITEC is developing an innovative Low-energy Planetary Excavator (LPE) to excavate in situ regolith, ice-regolith mixes, and a variety of other geologic materials...

  2. Level of selected toxic elements in meat, liver, tallow and bone marrow of young semi-domesticated reindeer (Rangifer tarandus tarandus L.) from Northern Norway

    National Research Council Canada - National Science Library

    Hassan, Ammar Ali; Rylander, Charlotta; Brustad, Magritt; Sandanger, Torkjel M

    2012-01-01

    .... Selected toxic elements (cadmium, lead, arsenic, nickel and vanadium) were studied. Liver was the organ with the highest level of all elements except for nickel, which was highest in bone marrow...

  3. Finite element study on the effect of abutment length and material on implant bone interface against dynamic loading.

    Science.gov (United States)

    Mishra, Manish; Ozawa, Shogo; Masuda, Tatsuhiko; Yoshioka, Fumi; Tanaka, Yoshinobu

    2011-09-01

    Finite element study on the effect of abutment length and material on implant bone interface against dynamic loading. Two dimensional finite element models of cylinderical implant, abutments and bone made by titanium or polyoxymethylene were simulated with the aid of Marc/Mentat software. Each model represented bone, implant and titanium or polyoxymethylene abutment. Model 1: Implant with 3 mm titanium abutment, Model 2: Implant with 2 mm polyoxymethylene resilient material abutment, Model 3: Implant with 3 mm polyoxymethylene resilient material abutment and Model 4: Implant with 4 mm polyoxymethylene resilient material abutment. A vertical load of 11 N was applied with a frequency of 2 cycles/sec. The stress distribution pattern and displacement at the junction of cortical bone and implant was recorded. When Model 2, 3 and 4 are compared with Model 1, they showed narrowing of stress distribution pattern in the cortical bone as the height of the polyoxymethylene resilient material abutment increases. Model 2, 3 and 4 showed slightly less but similar displacement when compared to Model 1. Within the limitation of this study, we conclude that introduction of different height resilient material abutment with different heights i.e. 2 mm, 3 mm and 4 mm polyoxymethylene, does not bring about significant change in stress distribution pattern and displacement as compared to 3 mm Ti abutment. Clinically, with the application of resilient material abutment there is no significant change in stress distribution around implant-bone interface.

  4. 18 CFR 1304.303 - Channel excavation.

    Science.gov (United States)

    2010-04-01

    ... 18 Conservation of Power and Water Resources 2 2010-04-01 2010-04-01 false Channel excavation... OF CONSTRUCTION IN THE TENNESSEE RIVER SYSTEM AND REGULATION OF STRUCTURES AND OTHER ALTERATIONS Activities on TVA Flowage Easement Shoreland § 1304.303 Channel excavation. (a) Channel excavation of...

  5. Experimental investigations and finite element simulation of cutting heat in vibrational and conventional drilling of cortical bone.

    Science.gov (United States)

    Wang, Yu; Cao, Meng; Zhao, Xiangrui; Zhu, Gang; McClean, Colin; Zhao, Yuanyuan; Fan, Yubo

    2014-11-01

    Heat generated during bone drilling could cause irreversible thermal damage, which can lead to bone necrosis or even osteomyelitis. In this study, vibrational drilling was applied to fresh bovine bones to investigate the cutting heat in comparison with conventional drilling through experimental investigation and finite element analysis (FEA). The influence of vibrational frequency and amplitude on cutting heat generation and conduction were studied. The experimental results showed that, compared with the conventional drilling, vibrational drilling could significantly reduce the cutting temperature in drilling of cortical bone (P<0.05): the cutting temperature tended to decrease with increasing vibrational frequency and amplitude. The FEA results also showed that the vibrational amplitude holds a significant effect on the cutting heat conduction.

  6. Bone

    Science.gov (United States)

    Helmberger, Thomas K.; Hoffmann, Ralf-Thorsten

    The typical clinical signs in bone tumours are pain, destruction and destabilization, immobilization, neurologic deficits, and finally functional impairment. Primary malignant bone tumours are a rare entity, accounting for about 0.2% of all malignancies. Also benign primary bone tumours are in total rare and mostly asymptomatic. The most common symptomatic benign bone tumour is osteoid osteoma with an incidence of 1:2000.

  7. Finite element analysis of dental implant loading on atrophic and non-atrophic cancellous and cortical mandibular bone - a feasibility study.

    Science.gov (United States)

    Marcián, Petr; Borák, Libor; Valášek, Jiří; Kaiser, Jozef; Florian, Zdeněk; Wolff, Jan

    2014-12-18

    The first aim of this study was to assess displacements and micro-strain induced on different grades of atrophic cortical and trabecular mandibular bone by axially loaded dental implants using finite element analysis (FEA). The second aim was to assess the micro-strain induced by different implant geometries and the levels of bone-to-implant contact (BIC) on the surrounding bone. Six mandibular bone segments demonstrating different grades of mandibular bone atrophy and various bone volume fractions (from 0.149 to 0.471) were imaged using a micro-CT device. The acquired bone STL models and implant (Brånemark, Straumann, Ankylos) were merged into a three-dimensional finite elements structure. The mean displacement value for all implants was 3.1 ±1.2 µm. Displacements were lower in the group with a strong BIC. The results indicated that the maximum strain values of cortical and cancellous bone increased with lower bone density. Strain distribution is the first and foremost dependent on the shape of bone and architecture of cancellous bone. The geometry of the implant, thread patterns, grade of bone atrophy and BIC all affect the displacement and micro-strain on the mandible bone. Preoperative finite element analysis could offer improved predictability in the long-term outlook of dental implant restorations.

  8. Validation of scaffold design optimization in bone tissue engineering: finite element modeling versus designed experiments.

    Science.gov (United States)

    Uth, Nicholas; Mueller, Jens; Smucker, Byran; Yousefi, Azizeh-Mitra

    2017-02-21

    This study reports the development of biological/synthetic scaffolds for bone tissue engineering (TE) via 3D bioplotting. These scaffolds were composed of poly(L-lactic-co-glycolic acid) (PLGA), type I collagen, and nano-hydroxyapatite (nHA) in an attempt to mimic the extracellular matrix of bone. The solvent used for processing the scaffolds was 1,1,1,3,3,3-hexafluoro-2-propanol. The produced scaffolds were characterized by scanning electron microscopy, microcomputed tomography, thermogravimetric analysis, and unconfined compression test. This study also sought to validate the use of finite-element optimization in COMSOL Multiphysics for scaffold design. Scaffold topology was simplified to three factors: nHA content, strand diameter, and strand spacing. These factors affect the ability of the scaffold to bear mechanical loads and how porous the structure can be. Twenty four scaffolds were constructed according to an I-optimal, split-plot designed experiment (DE) in order to generate experimental models of the factor-response relationships. Within the design region, the DE and COMSOL models agreed in their recommended optimal nHA (30%) and strand diameter (460 μm). However, the two methods disagreed by more than 30% in strand spacing (908 μm for DE; 601 μm for COMSOL). Seven scaffolds were 3D-bioplotted to validate the predictions of DE and COMSOL models (4.5-9.9 MPa measured moduli). The predictions for these scaffolds showed relative agreement for scaffold porosity (mean absolute percentage error of 4% for DE and 13% for COMSOL), but were substantially poorer for scaffold modulus (51% for DE; 21% for COMSOL), partly due to some simplifying assumptions made by the models. Expanding the design region in future experiments (e.g., higher nHA content and strand diameter), developing an efficient solvent evaporation method, and exerting a greater control over layer overlap could allow developing PLGA-nHA-collagen scaffolds to meet the mechanical requirements for

  9. Aguamilpa underground penstocks: Excavation phase

    Energy Technology Data Exchange (ETDEWEB)

    Mendez, F. (Comision Federal de Electricidad, Tepic, Nayarit (Mexico))

    1994-01-01

    The Aguamilpa hydroelectric project is one of a number of hydroelectric schemes currently being constructed along the course of the Santiago River in western Mexico. Aguamilpa will cost US$750 million and includes a 187-m concrete-faced rockfill dam, spillway and diversion tunnels, and a 960 MW underground powerhouse. The underground works include the penstocks, the powerhouse and surge chamber caverns, and the tailrace tunnel. In the initial design, most of the tunnelling work was to have been of a permanent nature. However, as the date of completion was brought forward to June 1993, it became necessary to open up more working faces and, as such, a number of temporary tunnels were started. The sequence of underground penstock excavation is described along with the construction methods developed and the equipment employed. It was originally intended to excavate the upper and lower ends of the penstocks and then raise-bore an initial pilot hole along the whole length. This hole would then be reamed out to the full diameter. To achieve faster completion, it was decided to excavate the lower portion of the penstocks from special access tunnels and to gain access to the top of the penstocks via geological exploration and drainage galleries. The horizontal parts of the penstocks were excavated by drill-and-blast methods, and the sloping parts were constructed by raise-boring a pilot hole and then using drill-and-blast to enlarge the hole in several stages to the full profile. Installation of steel liner sections will proceed upward and outward from the lower elbow section. 3 refs., 17 figs., 7 tabs.

  10. Fracture development around deep underground excavations: Insights from FDEM modelling

    Directory of Open Access Journals (Sweden)

    Andrea Lisjak

    2014-12-01

    Full Text Available Over the past twenty years, there has been a growing interest in the development of numerical models that can realistically capture the progressive failure of rock masses. In particular, the investigation of damage development around underground excavations represents a key issue in several rock engineering applications, including tunnelling, mining, drilling, hydroelectric power generation, and the deep geological disposal of nuclear waste. The goal of this paper is to show the effectiveness of a hybrid finite-discrete element method (FDEM code to simulate the fracturing mechanisms associated with the excavation of underground openings in brittle rock formations. A brief review of the current state-of-the-art modelling approaches is initially provided, including the description of selecting continuum- and discontinuum-based techniques. Then, the influence of a number of factors, including mechanical and in situ stress anisotropy, as well as excavation geometry, on the simulated damage is analysed for three different geomechanical scenarios. Firstly, the fracture nucleation and growth process under isotropic rock mass conditions is simulated for a circular shaft. Secondly, the influence of mechanical anisotropy on the development of an excavation damaged zone (EDZ around a tunnel excavated in a layered rock formation is considered. Finally, the interaction mechanisms between two large caverns of an underground hydroelectric power station are investigated, with particular emphasis on the rock mass response sensitivity to the pillar width and excavation sequence. Overall, the numerical results indicate that FDEM simulations can provide unique geomechanical insights in cases where an explicit consideration of fracture and fragmentation processes is of paramount importance.

  11. Biomechanical Consequences of the Elastic Properties of Dental Implant Alloys on the Supporting Bone: Finite Element Analysis

    OpenAIRE

    Esteban Pérez-Pevida; Aritza Brizuela-Velasco; David Chávarri-Prado; Antonio Jiménez-Garrudo; Fernando Sánchez-Lasheras; Eneko Solaberrieta-Méndez; Markel Diéguez-Pereira; Fernández-González, Felipe J.; Borja Dehesa-Ibarra; Francesca Monticelli

    2016-01-01

    The objective of the present study is to evaluate how the elastic properties of the fabrication material of dental implants influence peri-implant bone load transfer in terms of the magnitude and distribution of stress and deformation. A three-dimensional (3D) finite element analysis was performed; the model used was a section of mandibular bone with a single implant containing a cemented ceramic-metal crown on a titanium abutment. The following three alloys were compared: rigid (Y-TZP), conv...

  12. Biomechanical Consequences of the Elastic Properties of Dental Implant Alloys on the Supporting Bone: Finite Element Analysis

    Science.gov (United States)

    Chávarri-Prado, David; Jiménez-Garrudo, Antonio; Solaberrieta-Méndez, Eneko; Diéguez-Pereira, Markel; Fernández-González, Felipe J.; Dehesa-Ibarra, Borja; Monticelli, Francesca

    2016-01-01

    The objective of the present study is to evaluate how the elastic properties of the fabrication material of dental implants influence peri-implant bone load transfer in terms of the magnitude and distribution of stress and deformation. A three-dimensional (3D) finite element analysis was performed; the model used was a section of mandibular bone with a single implant containing a cemented ceramic-metal crown on a titanium abutment. The following three alloys were compared: rigid (Y-TZP), conventional (Ti-6Al-4V), and hyperelastic (Ti-Nb-Zr). A 150-N static load was tested on the central fossa at 6° relative to the axial axis of the implant. The results showed no differences in the distribution of stress and deformation of the bone for any of the three types of alloys studied, mainly being concentrated at the peri-implant cortical layer. However, there were differences found in the magnitude of the stress transferred to the supporting bone, with the most rigid alloy (Y-TZP) transferring the least stress and deformation to cortical bone. We conclude that there is an effect of the fabrication material of dental implants on the magnitude of the stress and deformation transferred to peri-implant bone. PMID:27995137

  13. Biomechanical Consequences of the Elastic Properties of Dental Implant Alloys on the Supporting Bone: Finite Element Analysis.

    Science.gov (United States)

    Pérez-Pevida, Esteban; Brizuela-Velasco, Aritza; Chávarri-Prado, David; Jiménez-Garrudo, Antonio; Sánchez-Lasheras, Fernando; Solaberrieta-Méndez, Eneko; Diéguez-Pereira, Markel; Fernández-González, Felipe J; Dehesa-Ibarra, Borja; Monticelli, Francesca

    2016-01-01

    The objective of the present study is to evaluate how the elastic properties of the fabrication material of dental implants influence peri-implant bone load transfer in terms of the magnitude and distribution of stress and deformation. A three-dimensional (3D) finite element analysis was performed; the model used was a section of mandibular bone with a single implant containing a cemented ceramic-metal crown on a titanium abutment. The following three alloys were compared: rigid (Y-TZP), conventional (Ti-6Al-4V), and hyperelastic (Ti-Nb-Zr). A 150-N static load was tested on the central fossa at 6° relative to the axial axis of the implant. The results showed no differences in the distribution of stress and deformation of the bone for any of the three types of alloys studied, mainly being concentrated at the peri-implant cortical layer. However, there were differences found in the magnitude of the stress transferred to the supporting bone, with the most rigid alloy (Y-TZP) transferring the least stress and deformation to cortical bone. We conclude that there is an effect of the fabrication material of dental implants on the magnitude of the stress and deformation transferred to peri-implant bone.

  14. Biomechanical Consequences of the Elastic Properties of Dental Implant Alloys on the Supporting Bone: Finite Element Analysis

    Directory of Open Access Journals (Sweden)

    Esteban Pérez-Pevida

    2016-01-01

    Full Text Available The objective of the present study is to evaluate how the elastic properties of the fabrication material of dental implants influence peri-implant bone load transfer in terms of the magnitude and distribution of stress and deformation. A three-dimensional (3D finite element analysis was performed; the model used was a section of mandibular bone with a single implant containing a cemented ceramic-metal crown on a titanium abutment. The following three alloys were compared: rigid (Y-TZP, conventional (Ti-6Al-4V, and hyperelastic (Ti-Nb-Zr. A 150-N static load was tested on the central fossa at 6° relative to the axial axis of the implant. The results showed no differences in the distribution of stress and deformation of the bone for any of the three types of alloys studied, mainly being concentrated at the peri-implant cortical layer. However, there were differences found in the magnitude of the stress transferred to the supporting bone, with the most rigid alloy (Y-TZP transferring the least stress and deformation to cortical bone. We conclude that there is an effect of the fabrication material of dental implants on the magnitude of the stress and deformation transferred to peri-implant bone.

  15. Simulation of acoustic guided wave propagation in cortical bone using a semi-analytical finite element method.

    Science.gov (United States)

    Pereira, Daniel; Haiat, Guillaume; Fernandes, Julio; Belanger, Pierre

    2017-04-01

    Axial transmission techniques have been extensively studied for cortical bone quality assessment. However, the modeling of ultrasonic guided waves propagation in such a complex medium remains challenging. The aim of this paper is to develop a semi-analytical finite element method to simulate the propagation of guided waves in an irregular, multi-layer, and heterogeneous bone cross-section modeled with anisotropic and viscoelastic material properties. The accuracy of the simulations was verified against conventional time-domain three-dimensional finite element. The method was applied in the context of axial transmission in bone to investigate the feasibility of first arrival signal (FAS) to monitor degradation of intracortical properties at low frequency. Different physiopathological conditions for the intracortical region, varying from healthy to osteoporotic, were monitored through FAS velocity using a 10-cycle tone burst excitation centered at 32.5 kHz. The results show that the variation in FAS velocity is mainly associated with four of the eight modes supported by the waveguide, varying with velocity values between 550 and 700 m/s along the different scenarios. Furthermore, the FAS velocity is shown to be associated with the group velocity of the mode with the highest relative amplitude contribution at each studied scenario. However, because of the evolution of the mode with the highest contribution, the FAS velocity is shown to be limited to discriminate intracortical bone properties at low frequency.

  16. MATHEMATICAL MODEL OF ATTITUDE CONTROL BUCKET‐WHEEL EXCAVATOR

    Directory of Open Access Journals (Sweden)

    Ivana ONDERKOVÁ

    2013-07-01

    Full Text Available This lecture deals with the application problems of convertibility GPS system at paddle excavator K 800. The claims of the modern operating surface mining of the excavators requires a lot of information for monitoring of mining process, capacity mining, selective extraction etc. The utilization of monitoring the excavator setting by GPS system proved to be the only one proper because the receivers are resistant to the vibration, dust, temperature divergence and weather changeable. Only the direct contact with communications satellite is required. It means that they can´t be located in a metal construction space (shadow caused by construction elements, influence of electrical high voltage cables even they can´t be located close to the paddle wheel on the paddle boom (shadow possibility caused by cuttinng edge created during lower gangplanks mining. This is the reason that GPS receivers are set uppermost on the metal construction excavator and the mathematical formulation is required for determination of paddle wheel petting. The relations for calculation of the paddle wheel coordinate were defined mathematically and after that the mathematical model was composed.

  17. Bone geometry on the contact stress in the shoulder for evaluation of pressure ulcers: finite element modeling and experimental validation.

    Science.gov (United States)

    Luo, Ying; Wang, Yancheng; Tai, Bruce L; Chen, Roland K; Shih, Albert J

    2015-02-01

    This research presents the finite element modeling (FEM) of human-specific computed tomography (CT) data to study the effect of bone prominences on contact stress in the shoulder for prevention of pressure ulcers. The 3D geometry of scapula, skin, and surrounding soft tissues in the shoulder was reconstructed based on the anonymous CT data of a human subject in a prone posture (without loading on the shoulder) for FEM analysis of the contact stress. FEM analysis results show that the maximum stress is located at the prominence of the scapula with sharp bone geometry. This demonstrates that stress concentration at the bone prominence is a significant factor to cause the high contact stress, which is a source for pressure ulcers. For experimental validation, a physical shoulder model manufactured by 3D printing of the bone geometry and the mold for molding of tissue-mimicking silicone was developed. Compression tests of the mattress foam and silicone were conducted to find the nonlinear stress-strain relations as inputs for FEM. Experiments of compressing the shoulder model against the foam were carried out. Three flexible force sensors were embedded inside the model to measure the contact forces and compared to the FEM predictions. Results show that the FEM predicted forces match well with the experimental measurements and demonstrate that FEM can accurately predict the stress distributions in the shoulder to study the effect of bone geometry on the inception of pressure ulcers.

  18. Reliability and Assessment Techniques on Ground Excavation

    Directory of Open Access Journals (Sweden)

    Sanga Tangchawal

    2009-05-01

    Full Text Available Planning and assessment on the excavation of the brittle materials (soil or rock can be done by using the machinery and/or explosives. The reliability assessment has been proposed to predict the failure of ground during excavation process. The stability planning on cutting soil (rock face by machinery can be compared between the deterministic and the statistical method. The risk of using explosives for rock excavation has to concern on the damage and environmental impacts after blasting events.

  19. Probability-based method using RFEM for predicting wall deflection caused by excavation

    Institute of Scientific and Technical Information of China (English)

    Yu-geng TANG

    2011-01-01

    This study employs the random finite element method (RFEM) to analyze the wall deflection caused by excavation.The RFEM combined random fields of material properties with the FEM through the Monte Carlo simulation.A well-documented excavation case history is employed to evaluate the influence of uncertainty of analysis parameters.This study shows that RFEM can provide reasonable estimations of the exceedance probability of wall deflection caused by excavation,and has the potential to be a useful tool to account for the uncertainties of material and model parameters in the numerical analysis.

  20. Correlation analysis between bone mineral density and serum element contents of postmenopausal women in Xi'an urban area.

    Science.gov (United States)

    Liu, Shun-Zhi; Yan, Hong; Xu, Peng; Li, Jian-Ping; Zhuang, Gui-Hua; Zhu, Bo-Feng; Lu, She-Min

    2009-12-01

    The objective of this paper is to investigate the correlation between serum macro-element and trace element contents and bone mineral density (BMD) as well as the occurrence of osteoporosis. After the epidemiological investigation of 290 postmenopausal women from ages 45 to 65 in the Xi'an urban area, their blood was collected and serum concentrations of macro-elements, calcium, phosphonium, potassium, sodium, magnesium, and trace elements, zinc, iron, copper, and selenium were determined using atomic absorption spectrometry. Their BMD was measured by QDR-2000 dual-energy X-ray absorptiometry (DEXA). The correlation analysis between BMD and serum element contents was done with the software of SPSS 13.0. The correlation analysis of serum elements of postmenopausal women showed that there was a significant correlation between serum calcium and the other elements, and also a significant correlation between serum phosphonium and the others except serum potassium. The serum potassium content had a significant correlation with serum calcium, sodium and iron, but sodium content showed a significant correlation with the others except iron and selenium. In addition, copper had a significant correlation with the others except potassium and selenium. In correlation analysis between BMD and the elements contents, only did the potassium content show a significant positive correlation with BMD of lumbar vertebra and proximal femora. The comparison results between osteoporosis group, osteopenia group, and healthy group showed that there was no significant difference in the element contents between the groups, but there existed a tendency that potassium content increased with the rise of BMD. There exist significant correlations between the contents of serum elements such as calcium, phosphonium, sodium, potassium, magnesium, zinc, iron, copper, and selenium, but no significant differences in these elements contents between the osteoporosis group, osteopenia group, and healthy

  1. A finite element analysis of two different dental implants: stress distribution in the prosthesis, abutment, implant, and supporting bone.

    Science.gov (United States)

    Quaresma, Sergio E T; Cury, Patricia R; Sendyk, Wilson R; Sendyk, Claudio

    2008-01-01

    This study evaluates the influence of 2 commercially available dental implant systems on stress distribution in the prosthesis, abutment, implant, and supporting alveolar bone under simulated occlusal forces, employing a finite element analysis. The implants and abutments evaluated consisted of a stepped cylinder implant connected to a screw-retained, internal, hexagonal abutment (system 1) and a conical implant connected to a solid, internal, conical abutment (system 2). A porcelain-covered, silver-palladium alloy was used as a crown. In each case, a simulated, 100-N vertical load was applied to the buccal cusp. A finite element model was created based on the physical properties of each component, and the values of the von Mises stresses generated in the prosthesis, abutment, implant, and supporting alveolar bone were calculated. In the prostheses, the maximum von Mises stresses were concentrated at the points of load application in both systems, and they were greater in system 1 (148 N/mm2) than in system 2 (55 N/mm2). Stress was greater on the abutment of system 2 than of system 1 on both the buccal (342 N/mm2 x 294 N/mm2) and lingual (294 N/mm2 x 148 N/ mm2) faces. Stress in the cortical, alveolar bone crest was greater in system 1 than in system 2 (buccal: 99.5 N/mm2 x 55 N/mm2, lingual: 55 N/mm2 x 24.5 N/mm2, respectively). Within the limits of this investigation, the stepped cylinder implant connected to a screw-retained, internal hexagonal abutment produces greater stresses on the alveolar bone and prosthesis and lower stresses on the abutment complex. In contrast, the conical implant connected to a solid, internal, conical abutment furnishes lower stresses on the alveolar bone and prosthesis and greater stresses on the abutment.

  2. Slope excavation quality assessment and excavated volume calculation in hydraulic projects based on laser scanning technology

    Directory of Open Access Journals (Sweden)

    Chao Hu

    2015-04-01

    Full Text Available Slope excavation is one of the most crucial steps in the construction of a hydraulic project. Excavation project quality assessment and excavated volume calculation are critical in construction management. The positioning of excavation projects using traditional instruments is inefficient and may cause error. To improve the efficiency and precision of calculation and assessment, three-dimensional laser scanning technology was used for slope excavation quality assessment. An efficient data acquisition, processing, and management workflow was presented in this study. Based on the quality control indices, including the average gradient, slope toe elevation, and overbreak and underbreak, cross-sectional quality assessment and holistic quality assessment methods were proposed to assess the slope excavation quality with laser-scanned data. An algorithm was also presented to calculate the excavated volume with laser-scanned data. A field application and a laboratory experiment were carried out to verify the feasibility of these methods for excavation quality assessment and excavated volume calculation. The results show that the quality assessment indices can be obtained rapidly and accurately with design parameters and scanned data, and the results of holistic quality assessment are consistent with those of cross-sectional quality assessment. In addition, the time consumption in excavation project quality assessment with the laser scanning technology can be reduced by 70%−90%, as compared with the traditional method. The excavated volume calculated with the scanned data only slightly differs from measured data, demonstrating the applicability of the excavated volume calculation method presented in this study.

  3. [Reaction of bone tissue elements on synthetic bioresorbable materials based on lactic and glycolic acids].

    Science.gov (United States)

    Kulakov, A A; Grigor'ian, A S

    2014-01-01

    The aim of the study was to evaluate the adverse effects of synthetic polymeric bioresorbable materials based on lactic and glycolic acids on the bone tissue. The study was carried-out on 40 Wister-line rats. Four types of bioresorbable polymeric materials were implanted: PolyLactide Glycolide Acid (PLGA), Poly-L-Lactide Acid (PLLA); Poly-96L/4D-Lactide Acid (96/4 PLDLA); Poly-70L/30D-Lactide Acid (70/30 PLDLA). The results showed connective tissue formation (fibrointegration) bordering bone adjacent to implanted materials. This proved the materials to cause pathogenic influence on the bone which mechanisms are described in the article.

  4. Toxic hazards of underground excavation

    Energy Technology Data Exchange (ETDEWEB)

    Smith, R.; Chitnis, V.; Damasian, M.; Lemm, M.; Popplesdorf, N.; Ryan, T.; Saban, C.; Cohen, J.; Smith, C.; Ciminesi, F.

    1982-09-01

    Inadvertent intrusion into natural or man-made toxic or hazardous material deposits as a consequence of activities such as mining, excavation or tunnelling has resulted in numerous deaths and injuries in this country. This study is a preliminary investigation to identify and document instances of such fatal or injurious intrusion. An objective is to provide useful insights and information related to potential hazards due to future intrusion into underground radioactive-waste-disposal facilities. The methodology used in this study includes literature review and correspondence with appropriate government agencies and organizations. Key categories of intrusion hazards are asphyxiation, methane, hydrogen sulfide, silica and asbestos, naturally occurring radionuclides, and various mine or waste dump related hazards.

  5. EFFECT OF OXIDATIVE STRESS ON HISTOARCHITECTONICS AND ELEMENTAL COMPOSITION OF BONE TISSUE OF THE VERTEBRAL BODY RATS

    Directory of Open Access Journals (Sweden)

    S. N. Lukanina

    2015-01-01

    Full Text Available This paper is concerned with study an influence of the oxidative stress on morphofunctional characteris-tics and elemental composition of bone tissue of the vertebral body rats.Material and methods. The research carried out on male rats of the Wistar line with weight 250–300 g. All rats were categorized into 4 groups with 10 ones in each: 1 – intact group; 2 and 3 – experimental groups; 4 – control group. Rats from groups 2–4 were under the development of oxidized stress which caused by daily stomach-pump injection (during fortnight with aqua suspension of synthetic glucocorticoid “Prednisolone” in dose 50 mg/kg. Through three hours after “Prednisolone” the antioxidant “Tiophan” was injected by stomach-pump (dose 100 mg/kg, which was dissolved in 0.2 ml of vegetation oil to laboratory animals from the group 2. Rats from control group got only solvent (vegetative oil 0.2 ml according the same scheme. Three hours after “Prednisolone” to rats from group 3 were injected of 0.2 ml aquaFontana. It was made for purity the experiment and standartization of manipulations, which are connected with injections into rats’ organisms. The peculiarities of structure of bone tissue of vertebra have been studied by methods of morphohystochemical analysis. The elemental composition of bone tissue was defined by atom-emission analysis method with inductive coupled plasma (spectrometer OPTIMA, code of methodics KHA: MUK.4.1.1482-03.Results. A development of glucocorticoid-induced oxidative stress results to infraction the histoarchitectonics of bone tissue of vertebra and decreasing the content of cations, which are included to the composition of active centres of pherments of antioxidant protection and prosthetic groups of proteins with an antioxidant activity. Using the antioxidant “Tiophan” proved an existence of its expressed osteoprotective properties. This can be seen from decreasing a level of resorbtion of bone tissue of

  6. Archaeology Excavation Simulation: Correcting the Emphasis

    Science.gov (United States)

    Thistle, Paul C.

    2012-01-01

    Museums offering archaeological programs often attempt to use the "sandbox approach" to simulate archaeological excavation work. However, in light of the definition of simulation, and given the realities of actual professional practice in archaeological excavation, the author argues that the activity of troweling for artifacts in loose sand places…

  7. Archaeology Excavation Simulation: Correcting the Emphasis

    Science.gov (United States)

    Thistle, Paul C.

    2012-01-01

    Museums offering archaeological programs often attempt to use the "sandbox approach" to simulate archaeological excavation work. However, in light of the definition of simulation, and given the realities of actual professional practice in archaeological excavation, the author argues that the activity of troweling for artifacts in loose sand places…

  8. Finite element analysis of steel fiber-reinforced concrete (SFRC): validation of experimental tensile capacity of dog-bone specimens

    Science.gov (United States)

    Islam, Md. Mashfiqul; Chowdhury, Md. Arman; Sayeed, Md. Abu; Hossain, Elsha Al; Ahmed, Sheikh Saleh; Siddique, Ashfia

    2014-09-01

    Finite element analyses are conducted to model the tensile capacity of steel fiber-reinforced concrete (SFRC). For this purpose dog-bone specimens are casted and tested under direct and uniaxial tension. Two types of aggregates (brick and stone) are used to cast the SFRC and plain concrete. The fiber volume ratio is maintained 1.5 %. Total 8 numbers of dog-bone specimens are made and tested in a 1000-kN capacity digital universal testing machine (UTM). The strain data are gathered employing digital image correlation technique from high-definition images and high-speed video clips. Then, the strain data are synthesized with the load data obtained from the load cell of the UTM. The tensile capacity enhancement is found 182-253 % compared to control specimen to brick SFRC and in case of stone SFRC the enhancement is 157-268 %. Fibers are found to enhance the tensile capacity as well as ductile properties of concrete that ensures to prevent sudden brittle failure. The dog-bone specimens are modeled in the ANSYS 10.0 finite element platform and analyzed to model the tensile capacity of brick and stone SFRC. The SOLID65 element is used to model the SFRC as well as plain concretes by optimizing the Poisson's ratio, modulus of elasticity, tensile strength and stress-strain relationships and also failure pattern as well as failure locations. This research provides information of the tensile capacity enhancement of SFRC made of both brick and stone which will be helpful for the construction industry of Bangladesh to introduce this engineering material in earthquake design. Last of all, the finite element outputs are found to hold good agreement with the experimental tensile capacity which validates the FE modeling.

  9. Biomechanical effects of bone cement volume on the endplates of augmented vertebral body: a three-dimensional finite element analysis

    Institute of Scientific and Technical Information of China (English)

    Yan Liang; Chang Zhen; Xu Zhengwei; Liu Tuanjiang; He Baorong; Hao Dingjun

    2014-01-01

    Background Previous studies have suggested that percutaneous vertebroplasty might alter vertebral stress transfer,leading to adjacent vertebral failure.However,no three-dimensional finite element study so far accounted for the stress distributions on different cement volumes.The purpose of this study was to evaluate the stress distributions on the endplate under different loading conditions after augmentation with various volumes of bone cement.Methods L2-L3 motion segment data were obtained from CT scans of the lumbar spine from a cadaver of a young man who had no abnormal findings on roentgenograms.Three-dimensional model of L2-L3 was established using Mimics software,and finite element model of L2-L3 functional spinal unit (FSU) was established using Ansys10.0 software.For simulating percutaneous vertebral augmentation,polymethylmethacrylate (PMMA) was deposited into the bipedicle of the L2 vertebra.The percentage of PMMA volume varied between 15% and 30%.The stress distributions on the endplate of the augmented vertebral body were calculated under three different loading conditions.Results In general,the stress level monotonically increased with bone cement volume.Under each loading condition,the stress change on the L2 superior and inferior endplates in three kinds of finite element models shows monotonic increase.Compared with the stress-increasing region of the endplate,the central part of the L2 endplate was subject to the greatest stress under three kinds of loading conditions,especially on the superior endplate and under flexion.Conclusions The finite element models of FSU are useful to optimize the planning for vertebroplasty.The bone cement volume might have an influence on the endplate of the augmentation,especially the superior endplate.It should be noted that the optimization of bone cement volume is patient specific; the volume of the bone cement should be based on the size,body mineral density,and stiffness of the vertebrae of individual

  10. Development of the software tool for generation and visualization of the finite element head model with bone conduction sounds

    Science.gov (United States)

    Nikolić, Dalibor; Milošević, Žarko; Saveljić, Igor; Filipović, Nenad

    2015-12-01

    Vibration of the skull causes a hearing sensation. We call it Bone Conduction (BC) sound. There are several investigations about transmission properties of bone conducted sound. The aim of this study was to develop a software tool for easy generation of the finite element (FE) model of the human head with different materials based on human head anatomy and to calculate sound conduction through the head. Developed software tool generates a model in a few steps. The first step is to do segmentation of CT medical images (DICOM) and to generate a surface mesh files (STL). Each STL file presents a different layer of human head with different material properties (brain, CSF, different layers of the skull bone, skin, etc.). The next steps are to make tetrahedral mesh from obtained STL files, to define FE model boundary conditions and to solve FE equations. This tool uses PAK solver, which is the open source software implemented in SIFEM FP7 project, for calculations of the head vibration. Purpose of this tool is to show impact of the bone conduction sound of the head on the hearing system and to estimate matching of obtained results with experimental measurements.

  11. Finite element modelling of rheological and penetration characteristics of curing PMMA bone cement in total hip replacement

    OpenAIRE

    2006-01-01

    This thesis is concerned with the study of the rheological properties of PMMA bone cement that is used as a grout for bone and prosthesis in THR and TKR Interdigitation of bone cement through porous cancellous bone depends on the rheological characteristics of bone cement and porosity of the cancellous bone. The rheological characteristics of the bone cement are thus an important factor effecting the optimum penetration of bone cement through cancellous bone. In this project the rheologic...

  12. Ion microprobe analysis of bone surface elements: Effects of 1,25(OH)2D3

    Energy Technology Data Exchange (ETDEWEB)

    Bushinsky, D.A.; Chabala, J.M.; Levi-Setti, R. (Univ. of Chicago, IL (USA))

    1989-12-01

    When neonatal mouse calvariae are incubated with 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) there is net calcium efflux from the bone into the medium. The effect of this enhanced cell-mediated Ca efflux on the relative concentrations of mineral 23Na, 39K, and 40Ca has not previously been studied. We used an imaging scanning ion microprobe, utilizing secondary ion mass spectrometry, to compare the relative ion concentrations of Na, K, and Ca on the surface, subsurface, and cross-section of cultured bone incubated in the presence of 1,25(OH)2D3 with the ion concentrations in similar regions of bone incubated in unaltered control medium. Changes in mineral ion concentration were correlated with net fluxes of Na, K, and Ca relative to bone. Calvariae incubated in control medium (24 h at pH approximately 7.40) have abundant surface Na and K relative to Ca (Na/Ca, 85 and K/Ca, 68), whereas the subsurface has less Na/Ca (21) and K/Ca (23), and on cross section the ratios of both Na/Ca (2.0) and K/Ca (1.9) decrease further. After incubation with 10(-8) M 1,25(OH)2D3, there is a significant increase in bone surface Na/Ca (154) and K/Ca (141) without a change in these ratios on the subsurface and a small fall in both ratios on cross section. The linear relationship between Na/Ca and K/Ca across the three regions of bone observed in control calvariae did not change with 1,25(OH)2D3 treatment. As determined by flux measurements there is a net efflux of Ca but not Na or K from bone.

  13. Optimization on cut-hole of mining tunnel excavation

    Institute of Scientific and Technical Information of China (English)

    ZHOU Chuan-bo; WANG peng; LEI Yong-jian; YIN Xiao-peng

    2009-01-01

    The efficiency of excavation a mining tunnel is definitely linked with modes of cut-holes. According to experience and methods of engineering analogy, the double-wedge cut, the 9-hole cut and the single spiral cut were determined originally by con-sidering the production conditions and blasting environment of the mining tunnels of the -74 m horizontal in the Da-ye iron mine. Based on acquired modes of cut-holes, the effect of the cut was studied, on the one hand, by a numerical simulation method with the aid of LS-DYNA3D, a nonlinear dynamic finite element program; on the other hand, a spot experiment was carried out in the mining tunnels. Both the numerical simulation and the spot experiment demonstrated and agreed that a single spiral cut provides the optimum excavation effect.

  14. Bone marrow stromal elements in murine leukemia; Decreased CSF-producing fibroblasts and normal IL-1 expression by macrophages

    Energy Technology Data Exchange (ETDEWEB)

    Ben-Ishay, Z. (Laboratory of Experimental Hematology, Department of Anatomy and Embryology, Hebrew University-Hadassah Medical School (Israel)); Barak, V. (Laboratory of Immunology, Department of Oncology, Hadassah University Hospital (Israel)); Shoshan, S. (Faculty of Dental Medicine, Connective Tissue Research Laboratory, Hebrew University, Jerusalem (Israel)); Prindull, G. (Department of Pediatrics, University of Gottingen, Gottingen (Germany, F.R.))

    1990-01-01

    A study of bone marrow stromal elements in murine acute myeloid leukemia (AML) was carried out. Our previous studies had indicated marrow stromal deficiency in murine AML. In the current investigation, separate stromal cells were cultured and the results obtained have shown that, while marrow stromal macrophages are normal in leukemia and express adequate amounts of IL-1, the fibroblasts are markedly reduced. However, if sufficient fibroblasts are pooled in vitro, they produce adequate amounts of CSF. Test of TNF{alpha} in leukemic cells CM, as possible cause of marrow stromal inhibition in leukemia, had not disclosed this cytokine. Further, it was observed that total body lethal irradiation of leukemic mice aggravates the stromal deficiency, confirming results of our previous investigations. It is concluded that bone marrow stromal deficiency in murine AML is due to decreased fibroblasts and, implicity, reduced CSF production. (author).

  15. Preliminary Study to Test the Feasibility of Sex Identification of Human (Homo sapiens) Bones Based on Differences in Elemental Profiles Determined by Handheld X-ray Fluorescence.

    Science.gov (United States)

    Nganvongpanit, Korakot; Buddhachat, Kittisak; Brown, Janine L; Klinhom, Sarisa; Pitakarnnop, Tanita; Mahakkanukrauh, Pasuk

    2016-09-01

    Sex assignment of human remains is a crucial step in forensic anthropological studies. The aim of this study was to examine elemental differences between male and female bones using X-ray fluorescence (XRF) and determine if elemental profiling could be used for sex discrimination. Cranium, humerus, and os coxae of 60 skeletons (30 male, 30 female) from the Chiang Mai University Skeletal Collection were scanned by XRF and differences in elemental profiles between male and female bones determined using discriminant analysis. In the cranium, three elements (S, Ca, Pb) were significantly higher in males and five elements (Si, Mn, Fe, Zn, Ag) plus light elements (atomic number lower than 12) were higher in females. In humerus and os coxae, nine elements were significantly higher in male and one element was higher in female samples. The accuracy rate for sex estimation was 60, 63, and 61 % for cranium, humerus, and os coxae, respectively, and 67 % when data for all three bones were combined. We conclude that there are sex differences in bone elemental profiles; however, the accuracy of XRF analyses for discriminating between male and female samples was low compared to standard morphometric and molecular methods. XRF could be used on small samples that cannot be sexed by traditional morphological methods, but more work is needed to increase the power of this technique for gender assignment.

  16. In vivo monitoring of bone-implant bond strength by microCT and finite element modelling.

    Science.gov (United States)

    Stadelmann, Vincent A; Conway, Carl M; Boyd, Steven K

    2013-01-01

    Immediately after implantation, a dynamic process of bone formation and resorption takes place around an orthopaedic implant, influencing its mechanical fixation. The delay until complete fixation depends on local bone architecture and metabolism. Despite its importance, the temporal pattern of implant fixation is still unknown. The optimal duration of post-operative care is therefore difficult to establish for an individual situation, and a method to evaluate non-invasively the evolution of the mechanical stability would be a significant asset in a clinical environment. The aim of this study was to evaluate the potential of micro-finite element modelling based on in vivo micro-computed tomography to monitor longitudinally the contact between bone and implant and the implant strength in vivo. The model was first validated for screw pull-out in synthetic bone surrogate. Correlation coefficients of R(2) = 0.94 and 0.85 (p < 0.01) were measured between experimental and numerical results for stiffness and failure loads, respectively. Then, the mechanical integration of screws in the proximal tibia of 12 rats was monitored at seven time points over a period of 1 month. We observed significant increases (p < 0.05) of bone-screw contact (+28%), stiffness (+93%) and failure load (+71%) over the course of the experiment, and more than 75% of these changes occurred during the first 2 weeks. Limitations, such as image artefacts and radiation, still compromise the immediate clinical application of this method, but it has a promising potential in preclinical animal studies, as it provides very valuable data about the dynamic aspect of implant integration with considerably reduced animal resources.

  17. Stress distribution of posts on the endodontically treated teeth with and without bone height augmentation: A three-dimensional finite element analysis

    Directory of Open Access Journals (Sweden)

    Sougaijam Vijay Singh

    2015-01-01

    Full Text Available Aims: Adequate bone support is an essential factor to avoid undue stress to the tooth. This is important when the tooth is endodontically treated and requires a post. The purpose of the present finite element (FE analysis study was to evaluate the stress distribution of post on endodontically treated tooth with reduced alveolar bone height support and after bone augmentation. The null hypothesis was that there is no difference between the stress distribution of post on endodontically treated teeth with reduced alveolar bone height support and after alveolar bone height augmented using bone graft substitute. Materials and Methods: The three-dimensional model was fabricated using ANSYS Workbench version 13.0 software to represent an endodontically treated mandibular second premolar restored with a full ceramic crown restoration and was analyzed using FE analysis. A load of 300N at an angle of 60° to the vertical was applied to the triangular ridge of the buccal cusp in a buccolingual plane. The stresses on the tooth with normal alveolar bone height, reduced alveolar bone height, and after bone augmentation because of reduced bone height were calculated using von misses stresses. Results: A maximum stress value of 136.04 MPa was observed in dentin with an alveolar bone height of 4 mm from the cemento-enamel junction (CEJ. However, after 2 mm of alveolar bone augmentation, the stress value was 104.32 MPa, which was comparable to the stress value of 105.56 observed with the normal bone height of 2 mm from the CEJ. Conclusion: Similar values of stresses were observed in teeth with normal and augmented bone height. Increased stresses were observed with alveolar bone loss of 4 mm from the CEJ.

  18. Relationship between sample volumes and modulus of human vertebral trabecular bone in micro-finite element analysis.

    Science.gov (United States)

    Wen, Xin-Xin; Xu, Chao; Zong, Chun-Lin; Feng, Ya-Fei; Ma, Xiang-Yu; Wang, Fa-Qi; Yan, Ya-Bo; Lei, Wei

    2016-07-01

    Micro-finite element (μFE) models have been widely used to assess the biomechanical properties of trabecular bone. How to choose a proper sample volume of trabecular bone, which could predict the real bone biomechanical properties and reduce the calculation time, was an interesting problem. Therefore, the purpose of this study was to investigate the relationship between different sample volumes and apparent elastic modulus (E) calculated from μFE model. 5 Human lumbar vertebral bodies (L1-L5) were scanned by micro-CT. Cubic concentric samples of different lengths were constructed as the experimental groups and the largest possible volumes of interest (VOI) were constructed as the control group. A direct voxel-to-element approach was used to generate μFE models and steel layers were added to the superior and inferior surface to mimic axial compression tests. A 1% axial strain was prescribed to the top surface of the model to obtain the E values. ANOVA tests were performed to compare the E values from the different VOIs against that of the control group. Nonlinear function curve fitting was performed to study the relationship between volumes and E values. The larger cubic VOI included more nodes and elements, and more CPU times were needed for calculations. E values showed a descending tendency as the length of cubic VOI decreased. When the volume of VOI was smaller than (7.34mm(3)), E values were significantly different from the control group. The fit function showed that E values approached an asymptotic values with increasing length of VOI. Our study demonstrated that apparent elastic modulus calculated from μFE models were affected by the sample volumes. There was a descending tendency of E values as the length of cubic VOI decreased. Sample volume which was not smaller than (7.34mm(3)) was efficient enough and timesaving for the calculation of E.

  19. Transfer of experimental allergic encephalomyelitis to bone marrow chimeras. Endothelial cells are not a restricting element

    Energy Technology Data Exchange (ETDEWEB)

    Hinrichs, D.J.; Wegmann, K.W.; Dietsch, G.N.

    1987-12-01

    The adoptive transfer of clinical and histopathologic signs of experimental allergic encephalomyelitis (EAE) requires MHC compatibility between cell donor and cell recipient. The results of adoptive transfer studies using F1 to parent bone marrow chimeras as recipients of parental-derived BP-sensitive spleen cells indicate that this restriction is not expressed at the level of the endothelial cell but is confined to the cells of bone marrow derivation. Furthermore, these results indicate that the development of EAE is not dependent on the activity of MHC-restricted cytotoxic cells.

  20. Research on Damage in Trabecular Bone of the Healthy Human Acetabulum at Small Strains Using Nonlinear Micro-finite Element Analysis

    Institute of Scientific and Technical Information of China (English)

    DING Hai; ZHU Zhen-nan; DAI Ke-rong; YE Ming; WANG Cheng-tao

    2008-01-01

    The mechanical properties of the pelvic trabecular bone have been studied at the continuum level. However, nothing is known about the tissue-level damage in the trabecular bone of the healthy human acetabulum at apparent small strains characteristic of habitual. By a DAWING 4000 A supercomputer, nonlinear micro-finite element (μFE) analysis was performed to quantify tissue-level damage accumulation in trabecular bone at small strains. The data indicate that damage in trabecular bone commence at 0.2% apparent strain. The findings imply that tissue yielding can initiate at very low strains in the trabecular bone of the healthy acetabulum and that this local failure has negative consequences on the apparent mechanical properties of trabecular bone.

  1. Simulation of a continuous lignite excavation system

    Energy Technology Data Exchange (ETDEWEB)

    Michalakopoulos, T.N.; Arvaniti, S.E.; Panagiotou, G.N. [National Technical University of Athens, Athens (Greece). Department of Mining Engineering

    2005-07-01

    A discrete-event simulation model using the GPSS/H simulation language has been developed for a excavation system at a multi- level terrace mine. The continuous excavation system consists of five bucket wheel excavators and a network of 22 km of belt conveyors. Ways of dealing with the continuous material flow and frequent changes of material type are considered. The principal model output variables are production and arrival rate at the transfer point of mineral and waste. Animation and comparison with previous production data have been used to validate the model. 14 refs., 6 figs., 1 tab.

  2. Trace elements determination in human bone tissue by neutron activation analysis; Determinacao de elementos de traco em tecido osseo humano pelo metodo de ativacao com neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Takata, Marcelo K.; Saiki, Mitiko [Instituto de Pesquisas Energeticas e Nucleares (IPEN), Sao Paulo, SP (Brazil). Div. de Radioquimica; Sumita, Nairo M.; Saldiva, Paulo H.N.; Pasqualucci, Carlos A. [Sao Paulo Univ., SP (Brazil). Faculdade de Medicina. Lab. Experimental de Poluicao Atmosferica

    2002-07-01

    Determination of trace elements in human bones is of the great interest for evaluating nutritional state and for prevention, control and study of several diseases caused by mineral or trace element imbalance. In this study, neutron activation analysis (NAA) was applied for trace elements in human rib bone tissue. Elements Ba, Br, Ca, Cl, Fe, K, Mg, Mn, Na, P, Rb, Sr and Zn were determined in total bone tissue and in its subcompartments (cortical and trabecular tissue) separately. Irradiations were performed at IEA-R1 nuclear research reactor of IPEN-CNEN/SP. Short irradiations of 4 minutes were carried out under thermal neutron flux of 4.5x10{sup 11} n cm{sup -2} s{sup -1} and long irradiations of 16 hours under neutron flux of 10{sup 12} n cm{sup -2} s{sup -1}. Results obtained showed a variability between elemental concentrations found for bones from different individuals. A comparative study made between the data obtained for cortical and trabecular bones indicated that these two tissues present different elemental concentrations. Concentrations of Ca, Mg, Na and P obtained for cortical tissue were the same magnitude of those published data. (author)

  3. Changes in Trace Element Contents and Morphology in Bones of Duck Exposed to Molybdenum or/and Cadmium.

    Science.gov (United States)

    Liao, Yilin; Cao, Huabin; Xia, Bing; Xiao, Qingyang; Liu, Ping; Hu, Guoliang; Zhang, Caiying

    2017-02-01

    Cadmium (Cd) and high molybdenum (Mo) can lead to adverse reactions on animals, but the coinduced toxicity of Mo and Cd to bone in ducks was not well understood. The objective of this study was to investigate the changes in trace elements' contents and morphology in bones of duck exposed to Mo or/and Cd. One hundred twenty healthy 11-day-old male ducks were randomly divided into six groups and treated with commercial diet containing Cd or/and Mo. On the 60th and 120th days, the blood, excretion, and metatarsals were collected to determine alkaline phosphatase (ALP) activity and the contents of Mo, Cd, calcium (Ca), phosphorus (P), copper (Cu), iron (Fe), zine (Zn), and selenium (Se). In addition, metatarsals were subjected to histopathological analysis with the optical microscope and radiography. The results indicated that Mo and Cd contents significantly increased while Ca, P, Cu, and Se contents remarkably decreased in metatarsals in coexposure groups (P Contents of Fe and Zn in metatarsals had no significant difference among groups (P > 0.05). Ca content in serum had no significant difference among experimental groups (P > 0.05), but P content was significantly decreased in HMo and HMo + Cd groups (P Contents of Ca and P in excretion and ALP activity were significantly increased in coinduced groups (P elements showed a possible synergistic relationship.

  4. The huge ATLAS cavern now fully excavated

    CERN Document Server

    2002-01-01

    Excavation of the ATLAS cavern is now complete! At the end of two years' work involving a tremendous technical challenge, the civil engineering contractors have succeeded in digging out one of the biggest experimental caverns in the world. Bravo!

  5. Study of the mechanical behavior of cortical bone microstructure by the finite element method

    OpenAIRE

    Arango Villegas, Camila

    2016-01-01

    [EN] Cortical bone tissue is the responsible of giving support and structure to vertebrates. For that reason, understanding and analyzing its behavior is needed from each different hierarchical level that composes it. The lower the structural scale is, the greater the complexity and scarcity of studies in literature. These studies are relevant for understanding, preventing and solving important health problems that affect human beings. From a mechanical point of view is interesting to eval...

  6. Study of paleodiet by means of the PIXE analysis of ancient human bones from Teotihuacan; Estudio de paleodieta mediante el analisis PIXE de restos oseos de Teotihuacan

    Energy Technology Data Exchange (ETDEWEB)

    Ruvalcaba S, J.L.; Becerra R, V. [IFUNAM, A.P. 20-364, 01000 Mexico D.F. (Mexico)

    2004-07-01

    This work focuses on the study of the paleodiet of individuals from Teotihuacan corresponding to the end of the Classic period and Mazapa phase. The analysis lies on the chemical composition variability of major and trace elements, such as Ca, Fe, Zn, Sr, and Ba among others, of bone remains. Particle Induced X-ray Emission Spectrometry (PIXE) was used to analyze the individual bone remains and sediments associated to the burial context. The bone remains were stripped of their external layer by mechanical cleaning, then powdered to prepare pellets. The bone and sediment pellets were irradiated using a 3 MeV proton beam and an external beam setup. Elemental concentrations of Ca, Fe, Zn, Sr and Ba, among other elements, were measured in bones and sediments from the archaeological excavations. An evaluation of the sample preparation, the effects of the archaeological context, as well as the paleodiet results are presented. (Author) 20 refs., 10 figs.

  7. Elemental Analysis of Bone, Teeth, Horn and Antler in Different Animal Species Using Non-Invasive Handheld X-Ray Fluorescence.

    Directory of Open Access Journals (Sweden)

    Kittisak Buddhachat

    Full Text Available Mineralized tissues accumulate elements that play crucial roles in animal health. Although elemental content of bone, blood and teeth of human and some animal species have been characterized, data for many others are lacking, as well as species comparisons. Here we describe the distribution of elements in horn (Bovidae, antler (Cervidae, teeth and bone (humerus across a number of species determined by handheld X-ray fluorescence (XRF to better understand differences and potential biological relevance. A difference in elemental profiles between horns and antlers was observed, possibly due to the outer layer of horns being comprised of keratin, whereas antlers are true bone. Species differences in tissue elemental content may be intrinsic, but also related to feeding habits that contribute to mineral accumulation, particularly for toxic heavy metals. One significant finding was a higher level of iron (Fe in the humerus bone of elephants compared to other species. This may be an adaptation of the hematopoietic system by distributing Fe throughout the bone rather than the marrow, as elephant humerus lacks a marrow cavity. We also conducted discriminant analysis and found XRF was capable of distinguishing samples from different species, with humerus bone being the best source for species discrimination. For example, we found a 79.2% correct prediction and success rate of 80% for classification between human and non-human humerus bone. These findings show that handheld XRF can serve as an effective tool for the biological study of elemental composition in mineralized tissue samples and may have a forensic application.

  8. Influence of Alveolar Bone Loss and Cement Layer Thickness on the Biomechanical Behavior of Endodontically Treated Maxillary Incisors: A 3-dimensional Finite Element Analysis.

    Science.gov (United States)

    Dal Piva, Amanda Maria de Oliveira; Tribst, João Paulo Mendes; Souza, Rodrigo Othávio de Assunção E; Borges, Alexandre Luiz Souto

    2017-05-01

    In order to understand the mechanical behavior of a weakened incisor, this study aimed to evaluate the stress distribution caused by different alveolar bone heights and cement layer thickness. A finite element analysis was conducted for this investigation. An intact maxillary central incisor was initially modeled, and the bone of the models was modified in order to simulate 4 levels of bone height: BL0 (no bone loss), BL1 (1/3 bone loss), BL2 (1/2 bone loss), and BL3 (2/3 bone loss). These teeth models were remodeled with a fiber post at 2 different cement thicknesses and restored with a ceramic crown; "A" refers to the well-adapted fiber post (0.3 mm) and "B" to the nonadapted fiber post (1 mm), resulting in 12 models. RelyX ARC (3M ESPE, St Paul, MN) cement was simulated for the cementation of the crowns and fiber posts for all groups. Numeric models received a load of 100 N on the lingual surface. All materials and structures were considered linear elastic, homogeneous, and isotropic. Numeric models were plotted and meshed with isoparametric elements, and results were expressed in maximum principal stress. For fiberglass posts, cement, and dentin, the highest stress concentration occurred in the groups with increased bone loss. For cortical bone, the highest values were for the groups with 1/3 bone loss. A greater thickness of cement layer concentrates more stress. More bone loss and greater CLT were the influential factors in concentrating the stress. Copyright © 2017 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

  9. A Three-Dimensional Finite Element Study on the Biomechanical Simulation of Various Structured Dental Implants and Their Surrounding Bone Tissues

    OpenAIRE

    Zhang, Gong; Yuan, Hai; Chen, Xianshuai; Wang, Weijun; Chen, Jianyu; Liang, Jimin; Zhang, Peng

    2016-01-01

    Background/Purpose. This three-dimensional finite element study observed the stress distribution characteristics of 12 types of dental implants and their surrounding bone tissues with various structured abutments, implant threads, and healing methods under different amounts of concentrated loading. Materials and Methods. A three-dimensional geometrical model of a dental implant and its surrounding bone tissue was created; the model simulated a screw applied with a preload of 200 N or a torque...

  10. 3D Modelling of a Tunnel Re-excavation in Soft Ground

    Directory of Open Access Journals (Sweden)

    M. Hilar

    2011-01-01

    Full Text Available The construction of the shallow tunnel at Brezno started using the Pre-Vault Method. The tunnel excavation, in complicated geological conditions, led to many difficulties which finally resulted in a collapse, when a significant part of the temporary tunnel lining collapsed. Various options for re-excavating the tunnel were evaluated prior to further construction. Finally a decision was made to separate the collapsed area into sections 9 m in length using 16 m-wide, transversally oriented pile walls, to improve the stability of the collapsed ground. The walls were constructed from the surface prior to excavation. It was also decided to re-excavate a collapsed area using the Sprayed Concrete Lining (SCL method. Due to problematic soft ground conditions, which had been made even worse by the collapse, some additional support measures had to be considered prior to re-excavation (ground improvement, micropile umbrellas embedded into the pile walls, etc.This paper describes numerical modelling of the tunnel re-excavation through the collapsed area. Initial calculations of the tunnel re-excavation were made using a 2D finite element method. Subsequently, further calculations to evaluate the rock mass behaviour in the collapsed area were provided in 3D. The 2D calculations were used to provide sensitivity studies, while 3D modelling was mainly used for evaluating the tunnel face stability (impact of the pile walls, impact of ground improvement together with other factors (length of advances, moment of the temporary invert closure, etc. The results of the modelling were compared with the monitoring results.The paper also briefly describes the construction experience (technical problems, performance of various support measures, etc. The excavation and the primary lining construction were completed in 2006, and the tunnel was opened for traffic in April 2007.

  11. A NEW NUMERICAL SCHEME FOR ELASTIC-PLASTIC SIMULATION OF EXCAVATION IN GEO-ENGINEERING

    Institute of Scientific and Technical Information of China (English)

    Wang Jianxue; Shen Xinpu; Liu Tianquan

    2000-01-01

    For the path dependency and nonlinearity introduced by incremental construction, numerical method has been widely used in deformation analysis of geo-engineering.In the numerical simulation scheme commonly used in the past, the excavating loads are extracted from nodal stresses, which are deduced linearly from the stresses at Gauss-point in finite element method.The unneglectable calculation error is contained in this process when elastic-plastic constitutive model is employed.The error mentioned above is analyzed in detail.Based on the analysis of excavation process and the principle of finite element theory, a new simulation scheme for excavation is proposed.At the end of this paper, an application in rock engineering is given out.

  12. Digital Servo Control of a Robotic Excavator

    Institute of Scientific and Technical Information of China (English)

    GU Jun; SEWARD Derek

    2009-01-01

    An electro-hydraulic control system is designed and implemented for a robotic excavator known as the Lancaster University Computerised and Intelligent Excavator (LUCIE). The excavator is being developed to autonomously dig trenches without human intervention. Since the behavior of the excavator arm is dominated by the nonlinear dynamics of the hydraulic actuators and by the large and unpredictable external disturbances when digging, it is difficult to provide adequate accurate, quick and smooth movement under traditional control methodology, e.g., PI/PID, which is comparable with that of an average human operator. The data-based dynamic models are developed utilizing the simplified refined instrumental variable (SRIV) identification algorithm to precisely describe the nonlinear dynamical behaviour of the electro-hydraulic actuation system. Based on data-based model and proportional-integral-plus (PIP) methodology, which is a non-minimal state space method of control system design based on the true digital control (TDC) system design philosophy, a novel control system is introduced to drive the excavator arm accurately, quickly and smoothly along the desired path. The performance of simulation and field tests which drive the bucket along straight lines beth demonstrate the feasibility and validity of the proposed control scheme.

  13. Biomechanical Evaluation of Different Fixation Methods for Mandibular Anterior Segmental Osteotomy Using Finite Element Analysis, Part Two: Superior Repositioning Surgery With Bone Allograft.

    Science.gov (United States)

    Kilinç, Yeliz; Erkmen, Erkan; Kurt, Ahmet

    2016-01-01

    In this study, the biomechanical behavior of different fixation methods used to fix the mandibular anterior segment following various amounts of superior repositioning was evaluated by using Finite Element Analysis (FEA). The three-dimensional finite element models representing 3 and 5 mm superior repositioning were generated. The gap in between segments was assumed to be filled by block bone allograft and resignated to be in perfect contact with the mandible and segmented bone. Six different finite element models with 2 distinct mobilization rate including 3 different fixation configurations, double right L (DRL), double left L (DLL), or double I (DI) miniplates with monocortical screws, correspondingly were created. A comparative evaluation has been made under vertical, horizontal and oblique loads. The von Mises and principal maximum stress (Pmax) values were calculated by finite element solver programme. The first part of our ongoing Finite Element Analysis research has been addressed to the mechanical behavior of the same fixation configurations in nongrafted models. In comparison with the findings of the first part of the study, it was concluded that bone graft offers superior mechanical stability without any limitation of mobilization and less stress on the fixative appliances as well as in the bone.

  14. The impact of bone and suture material properties on mandibular function in Alligator mississippiensis: testing theoretical phenotypes with finite element analysis

    Science.gov (United States)

    Reed, David A; Porro, Laura B; Iriarte-Diaz, Jose; Lemberg, Justin B; Holliday, Casey M; Anapol, Fred; Ross, Callum F

    2011-01-01

    Abstract The functional effects of bone and suture stiffness were considered here using finite element models representing three different theoretical phenotypes of an Alligator mississippiensis mandible. The models were loaded using force estimates derived from muscle architecture in dissected specimens, constrained at the 18th and 19th teeth in the upper jaw and 19th tooth of the lower jaw, as well as at the quadrate-articular joint. Stiffness was varied systematically in each theoretical phenotype. The three theoretical phenotypes included: (i) linear elastic isotropic bone of varying stiffness and no sutures; (ii) linear elastic orthotropic bone of varying stiffness with no sutures; and (iii) linear elastic isotropic bone of a constant stiffness with varying suture stiffness. Variation in the isotropic material properties of bone primarily resulted in changes in the magnitude of principal strain. By comparison, variation in the orthotropic material properties of bone and isotropic material properties of sutures resulted in: a greater number of bricks becoming either more compressive or more tensile, changing between being either dominantly compressive or tensile, and having larger changes in the orientation of maximum principal strain. These data indicate that variation in these model properties resulted in changes to the strain regime of the model, highlighting the importance of using biologically verified material properties when modeling vertebrate bones. When bones were compared within each set, the response of each to changing material properties varied. In two of the 12 bones in the mandible, varied material properties within sutures resulted in a decrease in the magnitude of principal strain in bricks adjacent to the bone/suture interface and decreases in stored elastic energy. The varied response of the mandibular bones to changes in suture stiffness highlights the importance of defining the appropriate functional unit when addressing relationships of

  15. Effects of dividing the transverse carpal ligament on the mechanical behavior of the carpal bones under axial compressive load: a finite element study.

    Science.gov (United States)

    Guo, Xin; Fan, Yubo; Li, Zong-Ming

    2009-03-01

    Transecting the transverse carpal ligament (TCL) is a routine procedure to surgically treat carpal tunnel syndrome; yet, its mechanical consequences on carpal bones are unclear. In this study, our intent was to perform a computational analysis of carpal biomechanics resulting from TCL release. A three-dimensional finite element model of the wrist was constructed, which included all the carpal bones, the distal ulna and radius, the proximal metacarpals and the interosseous ligaments. Cartilage layers of each bone were modeled manually according to anatomic visualization software. The TCL was also modeled in three dimensions and added to the bone model. A 100-Newton axial load was applied to the upper section of the second and third metacarpals. The effects of dividing the TCL on the displacements of the carpal bones and the contact stress distribution in the midcarpal joints were studied using a finite element analysis method. When the TCL was divided, the axial compressive load resulted in the carpal bones deviating more radially. More specifically, the carpal bones on the radial side of the capitate and lunate (i.e. the trapezium, trapezoid, and scaphoid) moved further toward the radius, and the carpal bones on the ulnar side of the capitate and lunate (i.e. hamate, triquetrum, and pisiform) moved further toward the metacarpals. The contact stresses and contact locations in the midcarpal joints changed as a result of dividing the TCL. The changes in displacements of carpal bones and the contact stress distributions in the midcarpal joints due to TCL release may be implicated for some of the postoperative complications associated with carpal tunnel release.

  16. Mechanical excavator performance in Yucca Mountain tuffs

    Energy Technology Data Exchange (ETDEWEB)

    Ozdemir, L. [Colorado School of Mines, Golden, CO (USA); Hansen, F.D. [Sandia National Labs., Albuquerque, NM (USA)

    1991-01-01

    A research effort of four phases is in progress at the Colorado School of Mines. The overall program will evaluate the cutability of welded tuff and other lithologies likely to be excavated at Yucca Mountain in the site characterization process. Several mechanical systems are considered with emphasis given to the tunnel boring machine. The research comprises laboratory testing, linear drag bit and disc cutter tests and potentially large-scale laboratory demonstrations to support potential use of a tunnel boring machine in welded tuff. Preliminary estimates of mechanical excavator performance in Yucca Mountain tuff are presented here. As phases of the research project are completed, well quantified estimates will be made of performance of mechanical excavators in the Yucca Mountain tuffs. 3 refs., 2 tabs.

  17. Vertebral Development and Ossification in the Siberian Sturgeon (Acipenser Baerii), with New Insights on Bone Histology and Ultrastructure of Vertebral Elements and Scutes.

    Science.gov (United States)

    Leprévost, Amandine; AzaÏs, Thierry; Trichet, Michael; Sire, Jean-Yves

    2017-03-01

    In order to improve our knowledge on the vertebral development, structure and mineralization in Acipenseriformes, we undertook a study in a growth series of reared Siberian sturgeons (Acipenser baerii) using in toto clear and stain specimens, histological and ultrastructural observations, X-ray micro-tomography, and solid state NMR analyses. Scutes were also studied to compare the tissue structure and mineralization of endoskeletal and dermal skeletal elements. This study completes and clarifies previous investigations on vertebral development and architecture in sturgeons, and brings original data on the structure of (i) the perichondral bone that is progressively deposited around the vertebral elements during ontogeny, (ii) the typical cartilage composing these elements, and (iii) the scutes. In addition we provide data on the mineralization process, on the nature of the bone mineral phase, and on the growth dynamics of the vertebral elements. Anat Rec, 300:437-449, 2017. © 2016 Wiley Periodicals, Inc.

  18. Pajarito Plateau archaeological surveys and excavations. II

    Energy Technology Data Exchange (ETDEWEB)

    Steen, C R

    1982-04-01

    Los Alamos National Laboratory continues its archaeological program of data gathering and salvage excavations. Sites recently added to the archaeological survey are described, as well as the results of five excavations. Among the more interesting and important discoveries are (1) the apparently well-established local use of anhydrous lime, and (2) a late pre-Columbian use of earlier house sites and middens for garden plots. Evidence indicated that the local puebloan population was the result of an expansion of upper Rio Grande peoples, not an influx of migrants.

  19. Diagnostic and analytical study of Punic terracotta pieces excavated from the archaelogical site of Mozia (Sicily

    Directory of Open Access Journals (Sweden)

    Enrico Acquaro

    2007-07-01

    Full Text Available The study on Punic terracotta elements excavated from the archaeological site of Mozia refers to some diagnostic and analytical examinations of ceramics, with a particular interest in the clay typology. It also draws our attention on the technique involved in the production of such products, from the making to the cooking.

  20. Influence of Regional Difference in Bone Mineral Density on Hip Fracture Site in Elderly Females by Finite Element Analysis.

    Science.gov (United States)

    Lin, Z L; Li, P F; Pang, Z H; Zheng, X H; Huang, F; Xu, H H; Li, Q L

    2015-11-01

    Hip fracture is a kind of osteoporotic fractures in elderly patients. Its important monitoring indicator is to measure bone mineral density (BMD) using DXA. The stress characteristics and material distribution in different parts of the bones can be well simulated by three-dimensional finite element analysis. Our previous studies have demonstrated a linear positive correlation between clinical BMD and the density of three-dimensional finite element model of the femur. However, the correlation between the density variation between intertrochanteric region and collum femoris region of the model and the fracture site has not been studied yet. The present study intends to investigate whether the regional difference in the density of three-dimensional finite element model of the femur can be used to predict hip fracture site in elderly females. The CT data of both hip joints were collected from 16 cases of elderly female patients with hip fractures. Mimics 15.01 software was used to reconstruct the model of proximal femur on the healthy side. Ten kinds of material properties were assigned. In Abaqus 6.12 software, the collum femoris region and intertrochanteric region were, respectively, drawn for calculating the corresponding regional density of the model, followed by prediction of hip fracture site and final comparison with factual fracture site. The intertrochanteric region/collum femoris region density was [(1.20 ± 0.02) × 10(6)] on the fracture site and [(1.22 ± 0.03) × 10(6)] on the non-fracture site, and the difference was statistically significant (P = 0.03). Among 16 established models of proximal femur on the healthy side, 14 models were consistent with the actual fracture sites, one model was inconsistent, and one model was unpredictable, with the coincidence rate of 87.5 %. The intertrochanteric region or collum femoris region with lower BMD is more prone to hip fracture of the type on the corresponding site.

  1. Micro-scale finite element modeling of ultrasound propagation in aluminum trabecular bone-mimicking phantoms: A comparison between numerical simulation and experimental results.

    Science.gov (United States)

    Vafaeian, B; Le, L H; Tran, T N H T; El-Rich, M; El-Bialy, T; Adeeb, S

    2016-05-01

    The present study investigated the accuracy of micro-scale finite element modeling for simulating broadband ultrasound propagation in water-saturated trabecular bone-mimicking phantoms. To this end, five commercially manufactured aluminum foam samples as trabecular bone-mimicking phantoms were utilized for ultrasonic immersion through-transmission experiments. Based on micro-computed tomography images of the same physical samples, three-dimensional high-resolution computational samples were generated to be implemented in the micro-scale finite element models. The finite element models employed the standard Galerkin finite element method (FEM) in time domain to simulate the ultrasonic experiments. The numerical simulations did not include energy dissipative mechanisms of ultrasonic attenuation; however, they expectedly simulated reflection, refraction, scattering, and wave mode conversion. The accuracy of the finite element simulations were evaluated by comparing the simulated ultrasonic attenuation and velocity with the experimental data. The maximum and the average relative errors between the experimental and simulated attenuation coefficients in the frequency range of 0.6-1.4 MHz were 17% and 6% respectively. Moreover, the simulations closely predicted the time-of-flight based velocities and the phase velocities of ultrasound with maximum relative errors of 20 m/s and 11 m/s respectively. The results of this study strongly suggest that micro-scale finite element modeling can effectively simulate broadband ultrasound propagation in water-saturated trabecular bone-mimicking structures.

  2. Finite element analysis of dental implant loading on atrophic and non-atrophic cancellous and cortical mandibular bone - a feasibility study

    NARCIS (Netherlands)

    Marcián, P.; Borák, L.; Valášek, J.; Kaiser, J.; Florian, Z.; Wolff, J.

    2014-01-01

    The first aim of this study was to assess displacements and micro-strain induced on different grades of atrophic cortical and trabecular mandibular bone by axially loaded dental implants using finite element analysis (FEA). The second aim was to assess the micro-strain induced by different implant g

  3. Implementation and Integration of a Finite Element Model into the Bone Remodeling Model to Characterize Skeletal Loading

    Science.gov (United States)

    Werner, C. R.; Lewandowski, B.; Boppana, A.; Pennline, J. A.

    2017-01-01

    NASA's Digital Astronaut Project is developing a bone physiology model to predict changes in bone mineral density over the course of a space mission. The model intends to predict bone loss due to exposure in microgravity as well as predicting bone maintenance due to mechanical stimulus generated by exercise countermeasures. These predictions will be used to inform exercise device efficacy and to help design exercise protocols that will maintain bone mineral density during long exposures to microgravity during spaceflight. The mechanical stimulus and the stresses that are exhibited on the bone are important factors for bone remodeling. These stresses are dependent on the types of exercise that are performed and vary throughout the bone due to the geometry. A primary area of focus for bone health is the proximal femur. This location is critical in transmitting loads between the upper and lower body and have been known to be a critical failure point in older individuals with conditions like osteoporosis.

  4. A Three-Dimensional Finite Element Study on the Biomechanical Simulation of Various Structured Dental Implants and Their Surrounding Bone Tissues.

    Science.gov (United States)

    Zhang, Gong; Yuan, Hai; Chen, Xianshuai; Wang, Weijun; Chen, Jianyu; Liang, Jimin; Zhang, Peng

    2016-01-01

    Background/Purpose. This three-dimensional finite element study observed the stress distribution characteristics of 12 types of dental implants and their surrounding bone tissues with various structured abutments, implant threads, and healing methods under different amounts of concentrated loading. Materials and Methods. A three-dimensional geometrical model of a dental implant and its surrounding bone tissue was created; the model simulated a screw applied with a preload of 200 N or a torque of 0.2 N·m and a prosthetic crown applied with a vertical or an inclined force of 100 N. The Von Mises stress was evaluated on the 12 types of dental implants and their surrounding bone tissues. Results. Under the same loading force, the stress influence on the implant threads was not significant; however, the stress influence on the cancellous bone was obvious. The stress applied to the abutment, cortical bone, and cancellous bone by the inclined force applied to the crown was larger than the stress applied by the vertical force to the crown, and the abutment stress of the nonsubmerged healing implant system was higher than that of the submerged healing implant system. Conclusion. A dental implant system characterised by a straight abutment, rectangle tooth, and nonsubmerged healing may provide minimum value for the implant-bone interface.

  5. A Three-Dimensional Finite Element Study on the Biomechanical Simulation of Various Structured Dental Implants and Their Surrounding Bone Tissues

    Directory of Open Access Journals (Sweden)

    Gong Zhang

    2016-01-01

    Full Text Available Background/Purpose. This three-dimensional finite element study observed the stress distribution characteristics of 12 types of dental implants and their surrounding bone tissues with various structured abutments, implant threads, and healing methods under different amounts of concentrated loading. Materials and Methods. A three-dimensional geometrical model of a dental implant and its surrounding bone tissue was created; the model simulated a screw applied with a preload of 200 N or a torque of 0.2 N·m and a prosthetic crown applied with a vertical or an inclined force of 100 N. The Von Mises stress was evaluated on the 12 types of dental implants and their surrounding bone tissues. Results. Under the same loading force, the stress influence on the implant threads was not significant; however, the stress influence on the cancellous bone was obvious. The stress applied to the abutment, cortical bone, and cancellous bone by the inclined force applied to the crown was larger than the stress applied by the vertical force to the crown, and the abutment stress of the nonsubmerged healing implant system was higher than that of the submerged healing implant system. Conclusion. A dental implant system characterised by a straight abutment, rectangle tooth, and nonsubmerged healing may provide minimum value for the implant-bone interface.

  6. Prediction and interpretation of the performance of a deep excavation in Berlin sand

    OpenAIRE

    Nikolinakou, Maria A.; Whittle, Andrew; Schran, Ute

    2009-01-01

    This paper describes the application of a generalized effective stress soil model, MIT‐S1, within a commercial finite element program, for simulating the performance of the support system for the 20m deep excavation of the M1 pit adjacent to the main station “Hauptbahnhof” in Berlin. The M1 pit was excavated underwater and supported by a perimeter diaphragm wall with a single row of prestressed anchors. Parameters for the soil model were based on an extensive program of laboratory tests on th...

  7. Modeling of excavation induced coupled hydraulic-mechanical processes in claystone

    Energy Technology Data Exchange (ETDEWEB)

    Massmann, Jobst

    2009-07-01

    Concepts for the numerical modeling of excavation induced processes in claystone are investigated. The study has been motivated by the international discussion on the adequacy of claystone as a potential host rock for a final repository of radioactive waste. The processes, which could impact the safety of such a repository, are manifold and strongly interacting. Thus, a multiphysics approach is needed, regarding solid mechanics and fluid mechanics within a geological context. A coupled modeling concept is therefore indispensable. Based on observations and measurements at an argillaceous test site (the underground laboratory Tournemire, operated by the Institute of Radioprotection and Nuclear Safety, France) the modeling concept is developed. Two main processes constitute the basis of the applied model: deformation (linear elasticity considering damage) and fluid flow (unsaturated one-phase flow). Several coupling phenomena are considered: Terzaghi 's effective stress concept, mass conservation of the liquid in a deformable porous media, drying induced shrinkage, and a permeability which depends on deformation and damage. In addition, transversely isotropic material behavior is considered. The numerical simulations are done with the finite element code RockFlow, which is extended to include: an orthotropic non-linear shrinkage model, a continuum damage model, and an orthotropic permeability model. For these new methods the theory and a literature review are presented, followed by applications, which illustrate the capability to model excavation induced processes in principle. In a comprehensive case study, the modeling concept is used to simulate the response of the Tournemire argillite to excavation. The results are compared with observations and measurements of three different excavations (century old tunnel, two galleries excavated in 1996 and 2003). In summary, it can be concluded that the developed model concept provides a prediction of the excavation

  8. Compromised trabecular microarchitecture and lower finite element estimates of radius and tibia bone strength in adults with turner syndrome

    DEFF Research Database (Denmark)

    Hansen, Stinus; Brixen, Kim; Gravholt, Claus H

    2012-01-01

    Although bone mass appear ample for bone size in Turner syndrome (TS), epidemiological studies have reported an increased risk of fracture in TS. We used high-resolution peripheral quantitative computed tomography (HR-pQCT) to measure standard morphological parameters of bone geometry and microar......Although bone mass appear ample for bone size in Turner syndrome (TS), epidemiological studies have reported an increased risk of fracture in TS. We used high-resolution peripheral quantitative computed tomography (HR-pQCT) to measure standard morphological parameters of bone geometry...

  9. Heathrow Terminal 5 Excavation Archive (Data Paper

    Directory of Open Access Journals (Sweden)

    Framework Archaeology

    2014-06-01

    Full Text Available Framework Archaeology is a Joint Venture agreement between Oxford Archaeology (OA and Wessex Archaeology (WA to provide archaeological services to BAA (formerly British Airports Authority, now Heathrow Airport Holdings Ltd. Given the potential scale of some of BAA's projects, the joint venture enables Framework Archaeology to draw on the full resources of both OA and WA, including site staff, specialist managers, administrative support, and technical facilities. In 1993, BAA plc and Heathrow Airport Limited submitted a joint planning application to develop an additional passenger terminal complex (Terminal 5, together with the provision of aircraft aprons and taxiways, and include the realignment of rivers and landscaping. The resulting archaeological excavations were undertaken as three main phases of work. Excavations in 1996 by the Museum of London Archaeology Service of approximately 4 ha of sludge stockpile areas (site code POK96. Between 1999-2000 Framework Archaeology excavated approximately 21 ha in the Perry Oaks sludge works and adjacent areas (WPR98. Framework Archaeology also undertook excavations between 2002-2007 as part of the construction of Terminal 5 (PSH02, TEC05 covering a further 50 hectares. Importantly the aim of the Terminal 5 archaeological programme was to move beyond the description and recovery of archaeological remains and to arrive at an understanding of the history of human inhabitation and the practical ways in which people established their presence in the material, social and political conditions of their day.

  10. Dilmun revisited: excavations at Saar, Bahrain

    Directory of Open Access Journals (Sweden)

    Harriet Crawford

    1997-11-01

    Full Text Available About 2000 BC the island of Bahrain was at the centre of a prosperous trading community - the Early Dilmun civilization - that stretched from Mesopotamia to the Indus Valley. Excavations at the site of Saar have, since 1989, recovered much new information about the layout of the settlement and its local economy and social system.

  11. Stepwise excavation in a permanent molar

    DEFF Research Database (Denmark)

    Lima, Fernanda Ferruzzi; Pascotto, Renata Corrêa; Benetti, Ana Raquel

    2010-01-01

    with zinc oxide cement were performed to minimize the risk of pulp exposure during excavation. After 45 days, the remaining carious tissue was removed and a restoration with glass-ionomer lining (Vitrebond) and resin composite (P-50) was performed. Satisfactory morphology and function of the restoration...

  12. Reviewing the Neolithisation phenomenon in the Lower Aragón region in the light of the excavation in the rock shelter of Valmayor xi (Mequinenza, Zaragoza

    Directory of Open Access Journals (Sweden)

    Manuel A. ROJO GUERRA

    2015-06-01

    Full Text Available This paper presents the preliminary results of the excavation of the Valmayor XI rock shelter, in the context of the research project ‘The pathways of the Neolithic’. Through the analysis of the radiocarbon dates and a detailed stratigraphic interpretation three occupations have been established with chronologies within different periods of the vith millennium cal bc. A general description of the archaeological events documented in each phase, and of most of the recovered material –pottery, lithic artefacts, bone industry and ornaments, faunal and carpological remains– is offered. Moreover, in the light of the new dates presented, a review of the Neolithisation process in the Lower Aragón region, and also in the Ebro valley, is proposed. Also the identification of archaeological sites as Neolithic ones only on the basis of the presence of some elements considered as ‘Neolithic markers’, without any consideration of the subsistence strategies or territorial exploitation, is questioned.

  13. MPED: An ISRU Bucket Ladder Excavator Demonstrator System Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Abstract: The Multi-Purpose Excavation Demonstrator (MPED) is a commercial effort and a third generation of technology, following Bucket Wheel Excavator and Bucket...

  14. Physical soil properties and slope treatments effects on hydraulic excavator productivity for forest road construction.

    Science.gov (United States)

    Parsakho, Aidin; Hosseini, Seyed Ataollah; Jalilvand, Hamid; Lotfalian, Majid

    2008-06-01

    Effects of moisture, porosity and soil bulk density properties, grubbing time and terrain side slopes on pc 220 komatsu hydraulic excavator productivity were investigated in Miana forests road construction project which located in the northern forest of Iran. Soil moisture and porosity determined by samples were taken from undisturbed soil. The elements of daily works were measured with a digital stop watch and video camera in 14 observations (days). The road length and cross section profiles after each 20 m were selected to estimate earthworks volume. Results showed that the mean production rates for the pc 220 komatsu excavators were 60.13 m3 h(-1) and earthwork 14.76 m h(-1) when the mean depth of excavation or cutting was 4.27 m3 m(-1), respectively. There was no significant effects (p = 0.5288) from the slope classes' treatments on productivity, whereas grubbing time, soil moisture, bulk density and porosity had significantly affected on excavator earthworks volume (p excavator earthworks length.

  15. Mechanical analysis about the influence of tunnel excavation on vertical effect of adjacent bridge pile

    Science.gov (United States)

    Tian, Xiaoyan

    2017-08-01

    Tunnel excavation will bring additional deformation and internal force of adjacent bridge piles, if the deformation is large, it will threat the upper structure safety of the bridge. According to the complexity of the existing three - dimensional numerical simulation modeling and the time - consuming calculation, a two - stage analysis method of tunnel excavation based on Winkler foundation model was proposed. Firstly, Loganathan and Polous solutions were used to obtain the vertical displacement of the soil free field at the pile position when tunnel excavated, and the corresponding polynomial fitting displacement curve was taken. Secondly, the differential equation was established by means of the equilibrium condition of micro - element physical force and considering the pile group effect. Then, through the logical derivation, the calculation expressions of the tunnel excavation on the effect of the adjacent bridge pile (settlement, axial force and friction resistance) were obtained. Finally, based on the background of the tunnel project of Yanxing Door Station ∼ Xianning Road Station in Xi’an Metro Line 3, the feasibility and applicability of the proposed method were proved by comparing the calculated values with the numerical simulation values. It provides theoretical guidance for the effective analysis about the influence of tunnel excavation on the adjacent pile foundation effect.

  16. The estimation of the possibilities of synchrotron radiation X-ray fluorescent analysis and atomic specrometry for the bone's elemental composition determination

    Science.gov (United States)

    Gonchar, A. M.; Kolmogorov, U. P.; Gladkikh, E. A.; Shuvaeva, O. V.; Beisel, N. F.; Kolosova, N. G.

    2005-05-01

    Possibilities of multielemental highly sensitive techniques of analysis have been studied: synchrotron radiation X-ray fluorescence analysis (SR XFA), and atomic emission spectrometry with inductively bound plasma (ISP) and atomic absorption spectrometry (AAS) with flame (air-acetylene) atomization for assay of element composition of bone tissue with minimal preparation procedure. Results of comparative studies of elemental composition of bone tissue samples from experimental animals with inherited accelerated aging (rats of OXYS strain) using the SR XFA, ISP and AAS techniques are presented. It is shown that there exists in principle a possibility of assay of 22 biologically important essential macro- and trace elements within the range of 1.0-100,000 μg/g with a mean square analysis error of no more them 10-15% when using SR XFA.

  17. Geotechnical analysis of deep excavation for the hotel Rimske Toplice

    OpenAIRE

    Škabar, Tjaša

    2011-01-01

    In my thesis I researched the Rimske Toplice excavation, which is located near Celje. The excavation pit depth is approximately 21 m. During excavation large displacements were observed in the southern part of the excavation, which damaged the construction. An analysis of existing situation was needed, then taking appropriate measures and finally remediation. Numerical calculations were done with Rocscience Slide 5.0, using lamel method by Spencer and Morgenstern/Price and with Plaxis 8.2...

  18. 29 CFR 1926.651 - Specific excavation requirements.

    Science.gov (United States)

    2010-07-01

    ..., DEPARTMENT OF LABOR (CONTINUED) SAFETY AND HEALTH REGULATIONS FOR CONSTRUCTION Excavations § 1926.651 Specific excavation requirements. (a) Surface encumbrances. All surface encumbrances that are located so as... 29 Labor 8 2010-07-01 2010-07-01 false Specific excavation requirements. 1926.651 Section 1926.651...

  19. Comparison of beam theory and finite-element analysis with in vivo bone strain data from the alligator cranium.

    Science.gov (United States)

    Metzger, Keith A; Daniel, William J T; Ross, Callum F

    2005-04-01

    The mechanical behavior of the vertebrate skull is often modeled using free-body analysis of simple geometric structures and, more recently, finite-element (FE) analysis. In this study, we compare experimentally collected in vivo bone strain orientations and magnitudes from the cranium of the American alligator with those extrapolated from a beam model and extracted from an FE model. The strain magnitudes predicted from beam and FE skull models bear little similarity to relative and absolute strain magnitudes recorded during in vivo biting experiments. However, quantitative differences between principal strain orientations extracted from the FE skull model and recorded during the in vivo experiments were smaller, and both generally matched expectations from the beam model. The differences in strain magnitude between the data sets may be attributable to the level of resolution of the models, the material properties used in the FE model, and the loading conditions (i.e., external forces and constraints). This study indicates that FE models and modeling of skulls as simple engineering structures may give a preliminary idea of how these structures are loaded, but whenever possible, modeling results should be verified with either in vitro or preferably in vivo testing, especially if precise knowledge of strain magnitudes is desired.

  20. The influence of residual root number and bone density on combined implant-residual tooth supported prosthesis after tooth hemisection: A finite element study.

    Science.gov (United States)

    He, Yun; Hasan, Istabrak; Chen, Junliang; Keilig, Ludger; Bourauel, Christoph

    2016-11-01

    The aim of the present study has been to analyze the influence of residual root number and bone density on the loading distribution of restorations combining implant and residual tooth after tooth hemisection using finite element analysis. Based on the image data of two patients, one has one distal root and the other has two distal roots in the mandibular right first molar, eight models were created (four models for each patient): a single crown was placed on the implant and residual tooth in two different bone densities; two separate crowns for the implant and residual tooth in two different bone densities. Vertical force of 100-N was applied on the crowns. The results show that the increase in number of residual roots decreased the magnitude of all biomechanical parameters. Higher values were observed in models with low bone density, especially in one distal root models. The maximum values of strains in spongious bone with the model (one distal root, low spongious bone density, a single crown was placed on the implant and residual tooth) even reached 9000μstrain. From a biomechanical point of view, when two residual roots exist, a single crown placed on the implant and distal half of the molar or two separate crowns for them seem to be an acceptable treatment option, regardless of the bone density. If there is one residual root and the bone density is low, the prosthesis which combines implant with the root might not be used. Copyright © 2016 Elsevier GmbH. All rights reserved.

  1. Level of selected toxic elements in meat, liver, tallow and bone marrow of young semi-domesticated reindeer (Rangifer tarandus tarandus L. from Northern Norway

    Directory of Open Access Journals (Sweden)

    Ammar Ali Hassan

    2012-04-01

    Full Text Available Objectives. To gain knowledge on toxic elements in semi-domesticated reindeer and their distribution in meat, liver, tallow and bone marrow. The correlations between concentrations in meat and liver, as well as the use of the latter as an indicator for toxic elements in meat, were also investigated. Study design. Cross-sectional study on population of semi-domesticated reindeer from 2 northern Norwegian counties (Finnmark and Nordland. Methods. Semi-domesticated reindeer carcasses (n = 31 were randomly selected, from which meat, liver, tallow and bone marrow samples were collected. Selected toxic elements (cadmium, lead, arsenic, nickel and vanadium were studied. Results. Liver was the organ with the highest level of all elements except for nickel, which was highest in bone marrow. Meat had the lowest levels, whereas levels in tallow and bone marrow were between those of meat and liver. Concentrations of cadmium, lead and arsenic were significantly different (p < 0.05 between meat and liver, while only arsenic and cadmium were significantly correlated in meat (rs=0.71, p < 0.01 and liver (rs=0.72, p < 0.01. The cadmium level exceeded the European Commission's (EC maximum level set for bovine meat and live in 52% of the liver samples (n = 29. Nevertheless, the estimated monthly cadmium intake from liver of 2.29 µg/kg body weight was well below the provisional tolerable monthly intake of 25 µg/kg body weight set by the FAO/WHO Joint Expert Committee on Food Additives. Conclusions. Based on the measured levels and their relation to the maximum level and to the provisional tolerable weekly/monthly intake limits, it could be inferred that consumption of reindeer meat is not associated with any health risk related to the studied toxic elements for consumers.

  2. Bone response from a dynamic stimulus on a one-piece and multi-piece implant abutment and crown by finite element analysis.

    Science.gov (United States)

    Hajimiragha, Habib; Abolbashari, Mohammadreza; Nokar, Saeed; Abolbashari, AmirHossein; Abolbashari, Mehrdad

    2014-10-01

    The present study was done to evaluate the effects of different types of abutments on the rate and distribution of stress on the bone surrounding the implant by dynamic finite element analysis method. In this study two ITI abutment models-one-piece and multi-piece-along with fixture, bone, and superstructure have been simulated with the help of company-made models. The maximum Von Mises stress (MVMS) was observed in the distobuccal area of the cortical bone near the crest of implant in two implant models. In the multi-piece abutment, MVMS was higher than the one-piece model (27.9 MPa and 23.3 MPa, respectively). Based on the results of this study, it can be concluded that type of abutment influences the stress distribution in the area surrounding the implant during dynamic loading.

  3. Finite Element Analysis of Bone Stress around Micro-Implants of Different Diameters and Lengths with Application of a Single or Composite Torque Force.

    Directory of Open Access Journals (Sweden)

    Ying-juan Lu

    Full Text Available Stress on the bone surrounding dental micro-implants affects implant success.To compare the stress on the bone surrounding a micro-implant after application of a single force (SF of 200 g or a composite force (CF of 200 g and 6 N.mm torque.Finite element models were developed for micro-implant diameters of 1.2, 1.6, and 2.0 mm, and lengths of 6, 8, 10, and 12 mm and either a SF or CF was applied. The maximum equivalent stress (Max EQS of the bone surrounding the micro-implant was determined, and the relationships among type of force, diameter, and length were evaluated.The Max EQS of the CF exceeded that of the SF (P 1.2 mm.

  4. Lightweight Bulldozer Attachment for Construction and Excavation on the Lunar Surface

    Science.gov (United States)

    Mueller, Robert; Wilkinson, R. Allen; Gallo, Christopher A.; Nick, Andrew J.; Schuler, Jason M.; King, Robert H.

    2009-01-01

    A lightweight bulldozer blade prototype has been designed and built to be used as an excavation implement in conjunction with the NASA Chariot lunar mobility platform prototype. The combined system was then used in a variety of field tests in order to characterize structural loads, excavation performance and learn about the operational behavior of lunar excavation in geotechnical lunar simulants. The purpose of this effort was to evaluate the feasibility of lunar excavation for site preparation at a planned NASA lunar outpost. Once the feasibility has been determined then the technology will become available as a candidate element in the NASA Lunar Surface Systems Architecture. In addition to NASA experimental testing of the LANCE blade, NASA engineers completed analytical work on the expected draft forces using classical soil mechanics methods. The Colorado School of Mines (CSM) team utilized finite element analysis (FEA) to study the interaction between the cutting edge of the LANCE blade and the surface of soil. FEA was also used to examine various load cases and their effect on the lightweight structure of the LANCE blade. Overall it has been determined that a lunar bulldozer blade is a viable technology for lunar outpost site preparation, but further work is required to characterize the behavior in 1/6th G and actual lunar regolith in a vacuum lunar environment.

  5. National Advanced Drilling and Excavation Technologies Program

    Energy Technology Data Exchange (ETDEWEB)

    None

    1993-06-15

    The second meeting of Federal agency representatives interested in the National Advanced Drilling and Excavation Technologies (NADET) Program took place on June 15, 1993. The Geothermal Division of the U.S. Department of Energy (DOE) hosted the meeting at the Washington, D.C., offices of DOE. Representatives from the National Science Foundation, U.S. Geological Survey, U.S. Bureau of Mines, National Institute of Standards and Technology, National Aeronautics and Space Administration, Environmental Protection Agency, and various offices within the Department of Energy attended. For a complete list of attendees see Attachment A. The purpose of the meeting was: (1) to cover the status of efforts to gain formal approval for NADET, (2) to brief participants on events since the last meeting, especially two recent workshops that explored research needs in drilling and excavation, (3) to review some recent technological advances, and (4) to solicit statements of the importance of improving drilling and excavation technologies to the missions of the various agencies. The meeting agenda is included as Attachment B.

  6. Influence of fine threads and platform-switching on crestal bone stress around implant-a three-dimensional finite element analysis.

    Science.gov (United States)

    Khurana, Pardeep; Sharma, Arun; Sodhi, Kiranmeet Kaur

    2013-12-01

    The aims of this study were to investigate the effect of implant fine threads on crestal bone stress compared to a standard smooth implant collar and to analyze how different abutment diameters influenced the crestal bone stress level. Three-dimensional finite element imaging was used to create a cross-sectional model in SolidWorks 2007 software of an implant (5-mm platform and 10 mm in length) placed in the premolar region of the mandible. The implant model was created to resemble a commercially available fine thread implant. Abutments of different diameters (5.0 mm: standard, 4.5 mm, 4.0 mm, and 3.5 mm) were loaded with a force of 100 N at 90° vertical and 40° oblique angles. Finite element analysis was done in COSMOSWorks software, which was used to analyze the stress patterns in bone, especially in the crestal region. Upon loading, the fine thread implant model had greater stress at the crestal bone adjacent to the implant than the smooth neck implant in both vertical and oblique loading. When the abutment diameter decreased progressively from 5.0 mm to 4.5 mm to 4 mm and to 3.5 mm the thread model showed a reduction of stress at the crestal bone level from 23.2 MPa to 15.02 MPa for fine thread and from 22.7 to 13.5 MPa for smooth collar implant group after vertical loading and from 43.7 MPa to 33.1 MPa in fine thread model and from 36.9 to 20.5 MPa in smooth collar implant model after oblique loading. Fine threads increase crestal stress upon loading. Reduced abutment diameter that is platform switching resulted in less stress translated to the crestal bone in the fine thread and smooth neck.

  7. On the development of an integrated bone remodeling law for orthodontic tooth movements models using the Finite Element Method.

    OpenAIRE

    Mengoni, Marlène

    2012-01-01

    One of the guiding principles in orthodontics is to gradually impose progressive and irreversible bone deformations due to remodeling using specific force systems on the teeth. Bone remodeling leads the teeth into new positions with two tissues having a major influence: the periodontal ligament and the alveolar bone. Their mechanical and biological/physiological reactions to orthodontic forces are tightly linked. This mechanical biological coupling can be treated in biomechanical mod...

  8. Full-face excavation of large tunnels in difficult conditions

    Institute of Scientific and Technical Information of China (English)

    Giovanni Barla

    2016-01-01

    Following a few preliminary remarks on the tunneling methods at the beginning of the 20th century, the successful applications of the full-face method also in difficult conditions are underlined. The attention is posed on the use of a systematic reinforcement of the face and of the ground, by means of fiber-glass elements. A selection of tunnels where this method was used successfully is reported with the pur-pose of illustrating the wide spectrum of ground conditions where it has been applied. Then, following a description of the main concepts behind the method, the attention moves from the so-called “heavy method”, where deformations are restrained, to the “light method”, where deformations are allowed with the intention to decrease the stresses acting on the primary and final linings. The progress in the application of the“light method”is underlined, up to the development of a novel technique, which relies on the use of a yielding support composed of top head steel sets with sliding joints and special deformable elements inserted in the primary lining. The well-known case study of the Saint Martin La Porte access adit, along the Lyon-Turin Base Tunnel, is described. In this tunnel, a yield-control support system combined with full-face excavation has been adopted successfully in order to cope with the large deformations experienced during face advance through the Carboniferous formation. The monitoring results obtained during excavation are illustrated, together with the modeling studies performed when paying attention to the rock mass time-dependent behavior.

  9. Full-face excavation of large tunnels in difficult conditions

    Directory of Open Access Journals (Sweden)

    Giovanni Barla

    2016-06-01

    Full Text Available Following a few preliminary remarks on the tunneling methods at the beginning of the 20th century, the successful applications of the full-face method also in difficult conditions are underlined. The attention is posed on the use of a systematic reinforcement of the face and of the ground, by means of fiber-glass elements. A selection of tunnels where this method was used successfully is reported with the purpose of illustrating the wide spectrum of ground conditions where it has been applied. Then, following a description of the main concepts behind the method, the attention moves from the so-called “heavy method”, where deformations are restrained, to the “light method”, where deformations are allowed with the intention to decrease the stresses acting on the primary and final linings. The progress in the application of the “light method” is underlined, up to the development of a novel technique, which relies on the use of a yielding support composed of top head steel sets with sliding joints and special deformable elements inserted in the primary lining. The well-known case study of the Saint Martin La Porte access adit, along the Lyon-Turin Base Tunnel, is described. In this tunnel, a yield-control support system combined with full-face excavation has been adopted successfully in order to cope with the large deformations experienced during face advance through the Carboniferous formation. The monitoring results obtained during excavation are illustrated, together with the modeling studies performed when paying attention to the rock mass time-dependent behavior.

  10. The influence of bone density and anisotropy in finite element models of distal radius fracture osteosynthesis: Evaluations and comparison to experiments.

    Science.gov (United States)

    Synek, A; Chevalier, Y; Baumbach, S F; Pahr, D H

    2015-11-26

    Continuum-level finite element (FE) models can be used to analyze and improve osteosynthesis procedures for distal radius fractures (DRF) from a biomechanical point of view. However, previous models oversimplified the bone material and lacked thorough experimental validation. The goal of this study was to assess the influence of local bone density and anisotropy in FE models of DRF osteosynthesis for predictions of axial stiffness, implant plate stresses, and screw loads. Experiments and FE analysis were conducted in 25 fresh frozen cadaveric radii with DRFs treated by volar locking plate osteosynthesis. Specimen specific geometries were captured using clinical quantitative CT (QCT) scans of the prepared samples. Local bone material properties were computed based on high resolution CT (HR-pQCT) scans of the intact radii. The axial stiffness and individual screw loads were evaluated in FE models, with (1) orthotropic inhomogeneous (OrthoInhom), (2) isotropic inhomogeneous (IsoInhom), and (3) isotropic homogeneous (IsoHom) bone material and compared to the experimental axial stiffness and screw-plate interface failures. FE simulated and experimental axial stiffness correlated significantly (posteosynthesis is essential whereas local bone anisotropy hardly effects the models׳ predictive abilities.

  11. Effect of labiolingual inclination of a maxillary central incisor and surrounding alveolar bone loss on periodontal stress: A finite element analysis

    Science.gov (United States)

    Choi, Sung-Hwan; Kim, Young-Hoon; Lee, Kee-Joon

    2016-01-01

    Objective The aim of this study was to investigate whether labial tooth inclination and alveolar bone loss affect the moment per unit of force (Mt/F) in controlled tipping and consequent stresses on the periodontal ligament (PDL). Methods Three-dimensional models (n = 20) of maxillary central incisors were created with different labial inclinations (5°, 10°, 15°, and 20°) and different amounts of alveolar bone loss (0, 2, 4, and 6 mm). The Mt/F necessary for controlled tipping (Mt/Fcont) and the principal stresses on the PDL were calculated for each model separately in a finite element analysis. Results As labial inclination increased, Mt/Fcont and the length of the moment arm decreased. In contrast, increased alveolar bone loss caused increases in Mt/Fcont and the length of the moment arm. When Mt/F was near Mt/Fcont, increases in Mt/F caused compressive stresses to move from a predominantly labial apical region to a palatal apical position, and tensile stresses in the labial area moved from a cervical position to a mid-root position. Although controlled tipping was applied to the incisors, increases in alveolar bone loss and labial tooth inclination caused increases in maximum compressive and tensile stresses at the root apices. Conclusions Increases in alveolar bone loss and labial tooth inclination caused increases in stresses that might cause root resorption at the root apex, despite the application of controlled tipping to the incisors. PMID:27226961

  12. Influence of Thread Pitch, Helix Angle, and Compactness on Micromotion of Immediately Loaded Implants in Three Types of Bone Quality: A Three-Dimensional Finite Element Analysis

    Directory of Open Access Journals (Sweden)

    Pan Ma

    2014-01-01

    Full Text Available This study investigated the influence of thread pitch, helix angle, and compactness on micromotion in immediately loaded implants in bone of varying density (D2, D3, and D4. Five models of the three-dimensional finite element (0.8 mm pitch, 1.6 mm pitch, 2.4 mm pitch, double-threaded, and triple-threaded implants in three types of bone were created using Pro/E, Hypermesh, and ABAQUS software. The study had three groups: Group 1, different pitches (Pitch Group; Group 2, same compactness but different helix angles (Angle Group; and Group 3, same helix angle but different compactness (Compact Group. Implant micromotion was assessed as the comprehensive relative displacement. We found that vertical relative displacement was affected by thread pitch, helix angle, and compactness. Under vertical loading, displacement was positively correlated with thread pitch and helix angle but negatively with compactness. Under horizontal loading in D2, the influence of pitch, helix angle, and compactness on implant stability was limited; however, in D3 and D4, the influence of pitch, helix angle, and compactness on implant stability is increased. The additional evidence was provided that trabecular bone density has less effect on implant micromotion than cortical bone thickness. Bone type amplifies the influence of thread pattern on displacement.

  13. Biomechanical evaluation of implant-supported prosthesis with various tilting implant angles and bone types in atrophic maxilla: A finite element study.

    Science.gov (United States)

    Gümrükçü, Zeynep; Korkmaz, Yavuz Tolga; Korkmaz, Fatih Mehmet

    2017-07-01

    The purpose of this study is to evaluate and compare bone stress that occurs as a result of using vertical implants with simultaneous sinus augmentation with bone stress generated from oblique implants without sinus augmentation in atrophic maxilla. Six, three-dimensional (3D) finite element (FE) models of atrophic maxilla were generated with SolidWorks software. The maxilla models were varied for two different bone types. Models 2a, 2b and 2c represent maxilla models with D2 bone type. Models 3a, 3b and 3c represent maxilla models with D3 bone type. Five implants were embedded in each model with different configurations for vertical implant insertion with sinus augmentation: Model 2a/Model 3a, 30° tilted insertion; Model 2b/Model 3b and 45° tilted insertion; Model 2c/Model 3c. A 150 N load was applied obliquely on the hybrid prosthesis. The maximum von Mises stress values were comparatively evaluated using color scales. The von Mises stress values predicted by the FE models were higher for all D3 bone models in both cortical and cancellous bone. For the vertical implant models, lower stress values were found in cortical bone. Tilting of the distal implants by 30° increased the stress in the cortical layer compared to vertical implant models. Tilting of the distal implant by 45° decreased the stress in the cortical bone compared to the 30° models, but higher stress values were detected in the 45° models compared to the vertical implant models. Augmentation should be the first treatment option in atrophic maxilla in terms of biomechanics. Tilted posterior implants can create higher stress values than vertical posterior implants. During tilting implant planning, the use of a 45° tilted implant results in better biomechanical performance in peri-implant bone than 30° tilted implant due to the decrease in cantilever length. Copyright © 2017 Elsevier Ltd. All rights reserved.

  14. Quantitative measures for assessment of the hydraulic excavator digging efficiency

    Institute of Scientific and Technical Information of China (English)

    Dragoslav JANOSEVIC; Rosen MITREV; Boban ANDJELKOVIC; Plamen PETROV

    2012-01-01

    In this paper,quantitative measures for the assessment of the hydraulic excavator digging efficiency are proposed and developed.The following factors are considered: (a) boundary digging forces allowed for by the stability of an excavator,(b) boundary digging forces enabled by the driving mechanisms of the excavator,(c) factors taking into consideration the digging position in the working range of an excavator,and (d) sign and direction of potential digging resistive force.A corrected digging force is defined and a mathematical model of kinematic chain and drive mechanisms of a five-member excavator configuration was developed comprising: an undercarriage,a rotational platform and an attachment with boom,stick,and bucket.On the basis of the mathematical model of the excavator,software was developed for computation and detailed analysis of the digging forces in the entire workspace of the excavator.By using the developed software,the analysis of boundary digging forces is conducted and the corrected digging force is determined for two models of hydraulic excavators of the same mass (around 17000 kg) with identical kinematic chain parameters but with different parameters of manipulator driving mechanisms.The results of the analysis show that the proposed set of quantitative measures can be used for assessment of the digging efficiency of existing excavator models and to serve as an optimization criterion in the synthesis of manipulator driving mechanisms of new excavator models.

  15. The effect of in situ/in vitro three-dimensional quantitative computed tomography image voxel size on the finite element model of human vertebral cancellous bone.

    Science.gov (United States)

    Lu, Yongtao; Engelke, Klaus; Glueer, Claus-C; Morlock, Michael M; Huber, Gerd

    2014-11-01

    Quantitative computed tomography-based finite element modeling technique is a promising clinical tool for the prediction of bone strength. However, quantitative computed tomography-based finite element models were created from image datasets with different image voxel sizes. The aim of this study was to investigate whether there is an influence of image voxel size on the finite element models. In all 12 thoracolumbar vertebrae were scanned prior to autopsy (in situ) using two different quantitative computed tomography scan protocols, which resulted in image datasets with two different voxel sizes (0.29 × 0.29 × 1.3 mm(3) vs 0.18 × 0.18 × 0.6 mm(3)). Eight of them were scanned after autopsy (in vitro) and the datasets were reconstructed with two voxel sizes (0.32 × 0.32 × 0.6 mm(3) vs. 0.18 × 0.18 × 0.3 mm(3)). Finite element models with cuboid volume of interest extracted from the vertebral cancellous part were created and inhomogeneous bilinear bone properties were defined. Axial compression was simulated. No effect of voxel size was detected on the apparent bone mineral density for both the in situ and in vitro cases. However, the apparent modulus and yield strength showed significant differences in the two voxel size group pairs (in situ and in vitro). In conclusion, the image voxel size may have to be considered when the finite element voxel modeling technique is used in clinical applications.

  16. THE STUDY OF BLOOD FLOW DYNAMICS IN TIBIAL SUBCHONDRAL EPIPHYSEAL ZONE OF PATIENTS WITH GONARTHROSIS AFTER TUNNELIZATION AND INFUSING AUTOLOGOUS BLOOD WITH BONE MARROW ELEMENTS

    Directory of Open Access Journals (Sweden)

    E. N. Shchurova

    2016-01-01

    Full Text Available Introduction. The knee osteoarthrosis leads to a significant reduction of working ability. as well as to disability of working-age people. Arthroplasty is dominated the main method in treatment of such patients. However, many orthopedists are more and more inclined to the surgeries which allow to preserve the knee anatomic-and-functional integrity and to delay the surgery of the knee total replacement for later periods. Subchondral tunnelization with infusing autologous blood with bone marrow elements is one of such methods. of treatment for the patients of this category.Purpose to study the dynamics of the blood flow in the tibial epiphyseal subchondral zone after tunnelization and infusing autologous blood with bone marrow elements and its effect on the rehabilitation process of patients with gonarthrosis.Material and methods. The work was based on the results of studying 26 patients with Degree grade 2-3 gonarthrosis. Surgical treatment included performing tunnelization of femoral and tibial condyles with infusing autologous blood containing bone marrow elements. Circulation of tibial subchondral epiphyseal zone was studied in the operation room, before surgery, after tunnelization and after infusing autologous blood. Blood flow registered using high-frequency ultrasonic Dopplerography. The patient functional condition and the pathology severity analyzed using complex index score.Results. The significant (42-108%, р<0.05 increase in blood flow registered in tibial subchondral epiphyseal zone in patients with gonarthrosis after tunnelization of femoral and tibial condyles in 46.2% of cases, and the increased blood flow persisted after infusing autologous blood with bone marrow elements in 58% of the patients from this group. In patients with significant blood flow increase the index score rate of gait, muscle strength and mean rehabilitation criterion was reliably 23% (р<0.05, 21% (р<0.05 and 17.4% (р<0.05 more, respectively, comparing

  17. 山西夏县东阴遗址调查试掘报告%A Report of the Excavation of Dongyin Site in Xiaxin,Shanxi

    Institute of Scientific and Technical Information of China (English)

    山西省考古研究所; 夏县博物馆

    2001-01-01

    Dongyin site of the Upper Erligang period(early Shang),locates at Dongyin village,about 7.5km south to Xiaxian town. For understanding the content and the nature of this site,especially for rescue purpose,we did a surveying and an excavation of 170m2 in Feb: 2000. Despite of various potteries and stones,a large of raw bone of the Upper Erligang period were found. These materials are important for our research on the procedure of bone artifact making and the nature of the site. The result of surveying of several time and one excavation of this site are reported in this paper.

  18. Characteristics of H2S emission from aged refuse after excavation exposure.

    Science.gov (United States)

    Shen, Dong-Sheng; Du, Yao; Fang, Yuan; Hu, Li-Fang; Fang, Cheng-Ran; Long, Yu-Yang

    2015-05-01

    Hydrogen sulfide (H2S(g)) emission from landfills is a widespread problem, especially when aged refuse is excavated. H2S(g) emission from aged refuse exposed to air was investigated and the results showed that large amounts of H2S(g) can be released, especially in the first few hours after excavation, when H2S(g) concentrations in air near refuse could reach 2.00 mg m(-3). Initial exposure to air did not inhibit the emission of H2S(g), as is generally assumed, but actually promoted it. The amounts of H2S(g) emitted in the first 2 d after excavation can be very dangerous, and the risks associated with the emission of H2S(g) could decrease significantly with time. Unlike a large number of sulfide existed under anaerobic conditions, the sulfide in aged municipal solid waste can be oxidized chemically to elemental sulfur (but not sulfate) under aerobic conditions, and its conversion rate was higher than 80%. Only microorganisms can oxidize the reduced sulfur species to sulfate, and the conversion rate could reach about 50%. Using appropriate techniques to enhance these chemical and biological transformations could allow the potential health risks caused by H2S(g) after refuse excavation to be largely avoided. Copyright © 2015 Elsevier Ltd. All rights reserved.

  19. Fast trabecular bone strength predictions of HR-pQCT and individual trabeculae segmentation-based plate and rod finite element model discriminate postmenopausal vertebral fractures.

    Science.gov (United States)

    Liu, X Sherry; Wang, Ji; Zhou, Bin; Stein, Emily; Shi, Xiutao; Adams, Mark; Shane, Elizabeth; Guo, X Edward

    2013-07-01

    Although high-resolution peripheral quantitative computed tomography (HR-pQCT) has advanced clinical assessment of trabecular bone microstructure, nonlinear microstructural finite element (µFE) prediction of yield strength using a HR-pQCT voxel model is impractical for clinical use due to its prohibitively high computational costs. The goal of this study was to develop an efficient HR-pQCT-based plate and rod (PR) modeling technique to fill the unmet clinical need for fast bone strength estimation. By using an individual trabecula segmentation (ITS) technique to segment the trabecular structure into individual plates and rods, a patient-specific PR model was implemented by modeling each trabecular plate with multiple shell elements and each rod with a beam element. To validate this modeling technique, predictions by HR-pQCT PR model were compared with those of the registered high-resolution micro-computed tomography (HR-µCT) voxel model of 19 trabecular subvolumes from human cadaveric tibia samples. Both the Young's modulus and yield strength of HR-pQCT PR models strongly correlated with those of µCT voxel models (r²  = 0.91 and 0.86). Notably, the HR-pQCT PR models achieved major reductions in element number (>40-fold) and computer central processing unit (CPU) time (>1200-fold). Then, we applied PR model µFE analysis to HR-pQCT images of 60 postmenopausal women with (n = 30) and without (n = 30) a history of vertebral fracture. HR-pQCT PR model revealed significantly lower Young's modulus and yield strength at the radius and tibia in fracture subjects compared to controls. Moreover, these mechanical measurements remained significantly lower in fracture subjects at both sites after adjustment for areal bone mineral density (aBMD) T-score at the ultradistal radius or total hip. In conclusion, we validated a novel HR-pQCT PR model of human trabecular bone against µCT voxel models and demonstrated its ability to discriminate vertebral fracture

  20. A finite element study to determine the occurrence of abfraction and displacement due to various occlusal forces and with different alveolar bone height

    Directory of Open Access Journals (Sweden)

    Kharidhi Laxman Vandana

    2016-01-01

    Full Text Available Background: Noncarious cervical lesions (NCCLs are rarely described in the periodontal literature, perhaps because no direct link between NCCLs and periodontal lesions has been demonstrated. Aim: The aim of this study is to determine the stress and displacement produced in the tooth at different bone levels under different occlusal load using finite element model (FEM study. Materials and Methods: Four FEMs of maxillary incisor were designed consisting of the tooth, pulp, periodontal ligament, and alveolar bone at the various level of bone height (25%, 50%, and 75%. Different occlusal load (5 kg, 15 kg, 24 kg, and 29 kg at an angle of 50° to the long axis of the tooth was applied on the palatal surface at the level of middle third of the crown. All the models were assumed to be isotropic, linear and elastic, and the analysis was performed on a Pentium IV processor computer using the ANSYS software. Results: The maximum stress in the tooth was seen in the cervical region and to a greater extent at the apex for all models. The maximum tooth displacement for all the occlusal loads applied in this study was at the incisal edge with the minimum tooth displacement at the cervical third of the root which shifted apically with the reduction of alveolar bone support. Conclusion: The cumulative effect of increased stress and displacement at the cervical region of the tooth would result in abfraction as the age advances along with other wasting diseases.

  1. Finite element analysis of equine incisor teeth. Part 2: investigation of stresses and strain energy densities in the periodontal ligament and surrounding bone during tooth movement.

    Science.gov (United States)

    Schrock, P; Lüpke, M; Seifert, H; Staszyk, C

    2013-12-01

    This study investigated the hypothetical contribution of biomechanical loading to the onset of equine odontoclastic tooth resorption and hypercementosis (EOTRH) and to elucidate the physiological age-related positional changes of the equine incisors. Based on high resolution micro-computed tomography (μCT) datasets, 3-dimensional models of entire incisor arcades and the canine teeth were constructed representing a young and an old incisor dentition. Special attention was paid to constructing an anatomically correct model of the periodontal ligament (PDL). Using previously determined Young's moduli for the equine incisor PDL, finite element (FE) analysis was performed. Resulting strains, stresses and strain energy densities (SEDs), as well as the resulting regions of tension and compression within the PDL and the surrounding bone were investigated during occlusion. The results showed a distinct distribution pattern of high stresses and corresponding SEDs in the PDL and bone. Due to the tooth movement, peaks of SEDs were obtained in the PDL as well as in the bone on the labial and palatal/lingual sides of the alveolar crest. At the root, highest SEDs were detected in the PDL on the palatal/lingual side slightly occlusal of the root tip. This distribution pattern of high SEDs within the PDL coincides with the position of initial resorptive lesions in EOTRH affected teeth. The position of high SEDs in the bone can explain the typical age-related alteration of shape and angulation of equine incisors.

  2. Quantifying the Effects of Formalin Fixation on the Mechanical Properties of Cortical Bone Using Beam Theory and Optimization Methodology With Specimen-Specific Finite Element Models.

    Science.gov (United States)

    Zhang, Guan-Jun; Yang, Jie; Guan, Feng-Jiao; Chen, Dan; Li, Na; Cao, Libo; Mao, Haojie

    2016-09-01

    The effects of formalin fixation on bone material properties remain debatable. In this study, we collected 36 fresh-frozen cuboid-shaped cortical specimens from five male bovine femurs and immersed half of the specimens into 4% formalin fixation liquid for 30 days. We then conducted three-point bending tests and used both beam theory method and an optimization method combined with specimen-specific finite element (FE) models to identify material parameters. Through the optimization FE method, the formalin-fixed bones showed a significantly lower Young's modulus (-12%) compared to the fresh-frozen specimens, while no difference was observed using the beam theory method. Meanwhile, both the optimization FE and beam theory methods revealed higher effective failure strains for formalin-fixed bones compared to fresh-frozen ones (52% higher through the optimization FE method and 84% higher through the beam theory method). Hence, we conclude that the formalin fixation has a significant effect on bovine cortical bones at small, elastic, as well as large, plastic deformations.

  3. Superior spatial resolution in confocal X-ray techniques using collimating channel array optics: elemental mapping and speciation in archaeological human bone

    Energy Technology Data Exchange (ETDEWEB)

    Choudhury, S.; Agyeman-Budu, D. N.; Woll, A. R.; Swanston, T.; Varney, T. L.; Cooper, D. M. L.; Hallin, E.; George, G. N.; Pickering, I. J.; Coulthard, I.

    2017-01-01

    Confocal X-ray fluorescence imaging (CXFI) and confocal X-ray absorption spectroscopy (CXAS) respectively enable the study of three dimensionally resolved localization and speciation of elements. Applied to a thick sample, essentially any volume element of interest within the X-ray fluorescence escape depth can be examined without the need for physical thin sectioning. To date, X-ray confocal detection generally has employed a polycapillary optic in front of the detector to collect fluorescence from the probe volume formed at the intersection of its focus with the incident microfocus beam. This work demonstrates the capability of a novel Collimating Channel Array (CCA) optic in providing an improved and essentially energy independent depth resolution approaching 2 μm. By presenting a comparison of elemental maps of archaeological bone collected without confocal detection, and with polycapillary- and CCA-based confocal detection, this study highlights the strengths and limitations of each mode. Unlike the polycapillary, the CCA shows similar spatial resolution in maps for both low (Ca) and high (Pb and Sr) energy X-ray fluorescence, thus illustrating the energy independent nature of the CCA optic resolution. While superior spatial resolution is demonstrated for all of these elements, the most significant improvement is observed for Ca, demonstrating the advantage of employing the CCA optic in examining light elements. In addition to CXFI, this configuration also enables the collection of Pb L3 CXAS data from micro-volumes with dimensions comparable to bone microstructures of interest. Our CXAS result, which represents the first CCA-based biological CXAS, demonstrates the ability of CCA optics to collect site specific spectroscopic information. The demonstrated combination of site-specific elemental localization and speciation data will be useful in diverse fields.

  4. Theory and technology of rock excavation for civil engineering

    CERN Document Server

    Zou, Dingxiang

    2017-01-01

    This book summarizes the technical advances in recent decades and the various theories on rock excavation raised by scholars from different countries, including China and Russia. It not only focuses on rock blasting but also illustrates a number of non-blasting methods, such as mechanical excavation in detail. The book consists of 3 parts: Basic Knowledge, Surface Excavation and Underground Excavation. It presents a variety of technical methods and data from diverse sources in the book, making it a valuable theoretical and practical reference resource for engineers, researchers and postgraduates alike.

  5. Pneumatic Excavation Mechanism for Lunar Resource Utilization Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Honeybee Robotics, in collaboration with Firestar Engineering, proposes to continue development of a pneumatic regolith excavating, moving and heating approach. With...

  6. Safety analysis of autonomous excavator functionality

    Energy Technology Data Exchange (ETDEWEB)

    Seward, D.; Pace, C.; Morrey, R.; Sommerville, I

    2000-10-01

    This paper presents an account of carrying out a hazard analysis to define the safety requirements for an autonomous robotic excavator. The work is also relevant to the growing generic class of heavy automated mobile machinery. An overview of the excavator design is provided and the concept of a safety manager is introduced. The safety manager is an autonomous module responsible for all aspects of system operational safety, and is central to the control system's architecture. Each stage of the hazard analysis is described, i.e. system model creation, hazard definition and hazard analysis. Analysis at an early stage of the design process, and on a system that interfaces directly to an unstructured environment, exposes certain issues relevant to the application of current hazard analysis methods. The approach taken in the analysis is described. Finally, it is explained how the results of the hazard analysis have influenced system design, in particular, safety manager specifications. Conclusions are then drawn about the applicability of hazard analysis of requirements in general, and suggestions are made as to how the approach can be taken further.

  7. Palaeoenvironmental signatures revealed from rare earth element (REE compositions of vertebrate microremains of the Vesiku Bone Bed (Homerian, Wenlock, Saaremaa Island, Estonia

    Directory of Open Access Journals (Sweden)

    Alexandre Fadel

    2015-02-01

    Full Text Available Rare earth elements (REEs have been analysed from fossil vertebrate microremains (thelodont scales from the Vesiku Bone Bed, Saaremaa, Estonia, using in situ microsampling by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS. Well-preserved scales of three species of the genus Thelodus (T. carinatus, T. laevis and Thelodus sp. show very uniform REE patterns with slightly lower overall REE concentrations in enameloid than in dentine, with enrichment in middle REEs, depletion in heavy REEs and pronounced negative europium anomaly, but no cerium anomaly. The results of this study suggest a similar diagenetic history and possibly contemporaneous habitats for all three Thelodus species, as well as possible suboxic to anoxic conditions of the bottom and pore waters during the formation of the Vesiku Bone Bed.

  8. Effect of type of luting agents on stress distribution in the bone surrounding implants supporting a three-unit fixed dental prosthesis: 3D finite element analysis.

    Science.gov (United States)

    Ghasemi, Ehsan; Abedian, Alireza; Iranmanesh, Pedram; Khazaei, Saber

    2015-01-01

    Osseointegration of dental implants is influenced by many biomechanical factors that may be related to stress distribution. The aim of this study was to evaluate the effect of type of luting agent on stress distribution in the bone surrounding implants, which support a three-unit fixed dental prosthesis (FDP) using finite element (FE) analysis. A 3D FE model of a three-unit FDP was designed replacing the maxillary first molar with maxillary second premolar and second molar as the abutments using CATIA V5R18 software and analyzed with ABAQUS/CAE 6.6 version. The model was consisted of 465108 nodes and 86296 elements and the luting agent thickness was considered 25 μm. Three load conditions were applied on eight points in each functional cusp in horizontal (57.0 N), vertical (200.0 N) and oblique (400.0 N, θ = 120°) directions. Five different luting agents were evaluated. All materials were assumed to be linear elastic, homogeneous, time independent and isotropic. For all luting agent types, the stress distribution pattern in the cortical bone, connectors, implant and abutment regions was almost uniform among the three loads. Furthermore, the maximum von Mises stress of the cortical bone was at the palatal side of second premolar. Likewise, the maximum von Mises stress in the connector region was in the top and bottom of this part. Luting agents transfer the load to cortical bone and different types of luting agents do not affect the pattern of load transfer.

  9. Effect of type of luting agents on stress distribution in the bone surrounding implants supporting a three-unit fixed dental prosthesis: 3D finite element analysis

    Science.gov (United States)

    Ghasemi, Ehsan; Abedian, Alireza; Iranmanesh, Pedram; Khazaei, Saber

    2015-01-01

    Background: Osseointegration of dental implants is influenced by many biomechanical factors that may be related to stress distribution. The aim of this study was to evaluate the effect of type of luting agent on stress distribution in the bone surrounding implants, which support a three-unit fixed dental prosthesis (FDP) using finite element (FE) analysis. Materials and Methods: A 3D FE model of a three-unit FDP was designed replacing the maxillary first molar with maxillary second premolar and second molar as the abutments using CATIA V5R18 software and analyzed with ABAQUS/CAE 6.6 version. The model was consisted of 465108 nodes and 86296 elements and the luting agent thickness was considered 25 μm. Three load conditions were applied on eight points in each functional cusp in horizontal (57.0 N), vertical (200.0 N) and oblique (400.0 N, θ = 120°) directions. Five different luting agents were evaluated. All materials were assumed to be linear elastic, homogeneous, time independent and isotropic. Results: For all luting agent types, the stress distribution pattern in the cortical bone, connectors, implant and abutment regions was almost uniform among the three loads. Furthermore, the maximum von Mises stress of the cortical bone was at the palatal side of second premolar. Likewise, the maximum von Mises stress in the connector region was in the top and bottom of this part. Conclusion: Luting agents transfer the load to cortical bone and different types of luting agents do not affect the pattern of load transfer. PMID:25709676

  10. Fish Remains from Excavations near the Riverfront at Newcastle upon Tyne, England

    Directory of Open Access Journals (Sweden)

    Rebecca A. Nicholson

    1997-12-01

    Full Text Available The City of Newcastle, situated some 10 miles inland on the River Tyne in north-east England, is not now an important fishing port. Most of the fresh fish marketed in the city has been landed at the nearby coastal ports of North and South Shields. Excavations at two sites behind the present Quayside in Newcastle, however, have yielded quantities of fish bones, representing a wide variety of species. This is in contrast to excavations in other parts of the city, where few fish remains have been recovered, and suggests that the quayside in Newcastle was an important centre for the fishing industry during the medieval period. It seems likely that most of the fish remains represent waste from landing and processing fish on or near the quayside. Yet, when taphonomic factors are taken into account, the limitations of using even large bone assemblages to interpret processing activities is demonstrated. As always, the need for a programme of on-site sieving to obtain representative samples of fish bone is evident.

  11. Three Dimensional Finite Element Analysis of Stress Distribution and Displacement of the Maxilla Following Surgically Assisted Rapid Maxillary Expansion with Tooth- and Bone-Borne Devices

    Directory of Open Access Journals (Sweden)

    Mohsen Dalband

    2015-10-01

    Full Text Available Objectives: The aim of this study was to investigate the displacement and stress distri- bution during surgically assisted rapid maxillary expansion under different surgical conditions with tooth- and bone-borne devices.Materials and Methods: Three-dimensional (3D finite element model of a maxilla was constructed and an expansion force of 100 N was applied to the left and right molars and premolars with tooth-borne devices and the left and right of mid-palatal sutures at the first molar level with bone-borne devices. Five CAD models were simulated as fol- lows and surgical procedures were used:  G1: control group (without surgery; G2: Le Fort I osteotomy; G3: Le Fort I osteotomy and para-median osteotomy; G4: Le Fort I osteotomy and pterygomaxillary separation; and G5: Le Fort I osteotomy, para-median osteotomy, and pterygomaxillary separation.Results: Maxillary displacement showed a gradual increase from group 1 to group 5 in all three planes of space, indicating that Le Fort I osteotomy combined with para-me- dian osteotomy and pterygomaxillary separation produced the greatest displacement of the maxilla with both bone- and tooth-borne devices. Surgical relief and bone-borne devices resulted in significantly reduced stress on anchored teeth.Conclusion: Combination of Le Fort I and para-median osteotomy with pterygomaxil-lary separation seems to be an effective procedure for increasing maxillary expansion, and excessive stress side effects are lowered around the anchored teeth with the use of bone-borne devices.

  12. Analysis of stress on mucosa and basal bone underlying complete dentures with different reliner material thicknesses: a three-dimensional finite element study.

    Science.gov (United States)

    Lima, J B G; Orsi, I A; Borie, E; Lima, J H F; Noritomi, P Y

    2013-10-01

    The aim of this study was to determine the optimal thickness of reliner material that provides the least amount of stress on thin mucosa and supporting bone in patients with complete removable dentures using a three-dimensional finite element analyses. The model was obtained from two CT scans of edentulous mandibles with dentures supported by the alveolar ridge. After virtual reconstruction, the three-dimensional models were exported to the solidworks cad software and divided into six groups based on the thickness of the reliner material as follows: (i) without material, (ii) 0·5 mm, (iii) 1 mm, (iv) 1·5 mm, (v) 2 mm and (vi) 2·5 mm. The applied load was 60 N and perpendicular to the long axis of the alveolar ridge of all the prosthetic teeth, and the mucosal thickness used was 1 mm. The analyses were based on the maximum principal stress in the fibromucosa and the minimum principal stress in the basal bone. Stress concentration was observed in the anterior zone of the mandible in the mucosa and in the bone. The maximum and minimum principal stress in the mucosa and bone, respectively, decreased, whereas the thickness of the reliner material increased until 2 mm, which transmitted the lowest stress, compared with the control. Reliner materials with a thickness of 2·5 mm showed higher stress values than those with a thickness of 2 mm. In conclusion, reliner material with a thickness of 2 mm transmitted the lowest amount of stress to the mucosa and bone in 1 mm of mucosa thickness.

  13. Bone trace element pattern in an 18th century population sample of Tenerife (Canary Islands): comparison with a prehistoric one.

    Science.gov (United States)

    Arnay-de-la-Rosa, M; Gonzalez-Reimers, E; Velasco-Vazquez, J; Barros-Lopez, N; Galindo-Martin, L

    1998-10-01

    We have determined bone strontium (Sr), barium (Ba), calcium (Ca), and zinc (Zn) content in 24 samples belonging to adult individuals who died toward the end of the 18th century and were interred in a church's floor on the island of Tenerife, comparing the results with those obtained in 14 prehistoric samples of the same island and also with those of 7 modern controls. No differences were observed between the two ancient groups, which showed higher bone strontium and barium than the modern sample, and a slightly lower Ba/Sr ratio, thus pointing to consumption of marine sources.

  14. The Gothic Elements in The Lovely Bones%《苏茜的世界》中的哥特元素

    Institute of Scientific and Technical Information of China (English)

    苏芳

    2014-01-01

    The Lovely Bones is a novel full of gothic elements,whose theme is revenge,main plot is murder and main features of char-acter images are bloodthirsty killing and psychopath.%《苏茜的世界》以复仇为主题,以谋杀为主要情节,以嗜血杀戮、心理变态为主要人物形象特征,是一部充满了哥特元素的小说。

  15. Preliminary results of excavations at Lincoln Cave, Sterkfontein, South Africa

    CSIR Research Space (South Africa)

    Reynolds, SC

    2003-05-01

    Full Text Available Recent excavations of undisturbed deposits within the Lincoln Cave, Sterkfontein, have conclusively demonstrated that at least one of the deposits is mid-late Pleistocene in age. The artefacts recovered from this excavation are in a datable context...

  16. Woodpecker Excavation and Use of Cavities in Polystyrene Snags

    Science.gov (United States)

    Richard N. Conner; Daniel Saenz

    1996-01-01

    We examined woodpecker excavation and use of artificial polystyrene snags in four forest types in eastern Texas for five years. Twenty-three of 47 artificial snags were used by Downy Woodpeckers (Picoides pubescens) for cavity excavation and subsequent nocturnal roosting; they did not use the artificial snags for nesting. Although six ather species of woodpeckers...

  17. Combination of Fault Tree and Neural Networks in Excavator Diagnosis

    Directory of Open Access Journals (Sweden)

    Li Guoping

    2013-04-01

    Full Text Available By using the theory of artificial intelligence fault diagnosis of hydraulic excavator of several basic problems are discussed in this paper, the artificial intelligence neural network model is established for the fault diagnosis of hydraulic system; the combined application of fault diagnosis analysis (FTA and artificial neural network is evaluated. In view of the hydraulic excavator failure symptom of dispersion and fuzziness, the fault diagnosis method was presented based on the fault tree and fuzzy neural network. On the basis of analysis of the hydraulic excavator system works, the fault tree model of hydraulic excavator was built by using fault diagnosis tree. And then, utilizing the example of hydraulic excavator fault diagnosis, the method of building neural network, obtaining training samples and neural network learning in the process of intelligent fault diagnosis are expounded. And the status monitoring data of hydraulic excavator was used as the sample data source. Using fuzzy logic methods the samples were blurred. The fault diagnosis of hydraulic excavator was achieved with BP neural network. The experimental result demonstrated that the information of sign failure was fully used through the algorithm. The algorithm was feasible and effective to fault diagnosis of hydraulic excavator. A new diagnosis method was proposed for fault diagnosis of other similar device.

  18. AUTOMATED DYNAMIC LOAD CONTROL BY ELECTROMECHANICAL SYSTEMS OF A BUCKET-CHAIN EXCAVATOR IN THE COURSE OF SCOOPING

    Directory of Open Access Journals (Sweden)

    Khayrullin Rustam Zinnatullovich

    2012-10-01

    Full Text Available Methods and algorithms of control of the tension of lifting and towing ropes of bucket-chain excavators are proposed in the article. They are based on the non-linear dependence of the current path length and intensity of excavation efforts. Three automatic control modes, including scooping, correction signals and automatic overload protection, are implemented. Two independent control loops in charge of tension of lifting and towing ropes are developed. The proposed automated control system may be integrated both into new bucket-chain excavators and into those excavators that are already in operation. The new system does not require any substantial alterations in electric drive control systems in charge of lifting and towing, if integrated into excavators in operation. The author has performed the non-linearity analysis; he has also designed, developed and implemented the models that are capable of taking an adequate account of the system peculiarities identified in the course of the project implementation. The system parameters are adjustable to specific conditions of the excavator operation, including the hardness of the rock extracted by the excavator, etc. The automatic overload control system attached to the electric drives in control of lifting and towing ensures maximal responsiveness of the system based on the commutation-related limitations imposed by power-driven elements, maximal over-control values and variability of the transition process. Prevention of any rope slacks in the course of scooping of any hard rock is assured by the loop of regulation of minimal tension of lifting cables. The service life of lifting and towing ropes goes up by eight to ten weeks, if the system proposed by the author is implemented.

  19. Rational design and synthesis of excavated trioctahedral Au nanocrystals

    Science.gov (United States)

    Chen, Qiaoli; Jia, Yanyan; Shen, Wei; Xie, Shuifen; Yang, Yanan; Cao, Zhenming; Xie, Zhaoxiong; Zheng, Lansun

    2015-06-01

    Excavated polyhedral nanostructures, possessing the features of high surface area and well-defined surface structure with a specific crystal facet and avoidance of aggregation, could be one of the best choices for the purpose of reducing consumption and improving performance of noble metals in many application fields. However, the formation of the excavated structures is thermodynamically unfavourable and its rational synthesis is far beyond our knowledge. In this work, taking overgrowth of Pd onto trioctahedral Au nanocrystals as a model, we present a deep insight study for synthesizing an excavated structure relying on the protection role of surfactants under suitable crystal growth kinetics. Based on the abovementioned understanding, we designed a simple and effective strategy to synthesize Au nanocrystals with excavated trioctahedral structure in one step. Due to the novel feature of the excavated structure and exposed high energy {110} facets, excavated trioctahedral Au NCs exhibited optical extinction at the near-infrared region and showed high catalytic activity towards the reduction of p-nitrophenol. Moreover, the synthetic strategy can be extended to the synthesis of excavated Au-Pd alloys.Excavated polyhedral nanostructures, possessing the features of high surface area and well-defined surface structure with a specific crystal facet and avoidance of aggregation, could be one of the best choices for the purpose of reducing consumption and improving performance of noble metals in many application fields. However, the formation of the excavated structures is thermodynamically unfavourable and its rational synthesis is far beyond our knowledge. In this work, taking overgrowth of Pd onto trioctahedral Au nanocrystals as a model, we present a deep insight study for synthesizing an excavated structure relying on the protection role of surfactants under suitable crystal growth kinetics. Based on the abovementioned understanding, we designed a simple and effective

  20. Evaluation of Strain Distribution in Bone around Implant in Treatment Design of Overdentures Using Computer and Modeling of Finite Elements

    Directory of Open Access Journals (Sweden)

    Masoumeh Khoshhal

    2015-12-01

    Full Text Available Introduction: Introduction: Few studies have investigated the distribution of stress around implants. In this study the distribution of stress in bones around implants was investigated in five overdenture (OD treatment designs including OD-1, OD-2, OD-3, OD-4 and OD-5. Materials and methods: The Catia modeling software was used in order to simulate the tooth/implant model and bone. First, the borders of cancellous and cortical bone in each section of the CT images were attained by Photoshop software. Then, modeling softwares SolidWorks and NUMBER were applied to make the final three-dimensional model of jaw. Finally, the amount of stress on the surface of bone/implant was studied by means of stress analysis software (Ansys v11.0. Results: Protrusive movements of implants B and D in OD-1 showed the highest amount of strain, 2435 εµ. Also, high amounts of strain, 1668 and 1557 εµwere observed in OD-1 and OD-2 designs in lateral movements respectively. Conclusion: The bottom line is that no forces to the extent of destruction based on the Ferost model were found for these designs. The highest amount of strain occurred in OD-1 design, which is held in mild overload window. Moreover, the amounts of strain in the rest of designs investigated were in adaptive window.

  1. A new method to determine trabecular bone elastic properties and loading using micromechanical finite-element models

    NARCIS (Netherlands)

    R. van Rietbergen (Bert); H.H. Weinans (Harrie); R. Huiskes (Rik); A. Odgaard

    1995-01-01

    textabstractThe apparent mechanical behavior of trabecular bone depends on properties at the tissue or trabecular level. Many investigators have attempted to determine trabecular tissue properties and loading. However, accuracy and applicability of all methods reported are limited. The small size of

  2. Evaluation of Strain Distribution in Bone around Implant in Treatment Design of Overdentures Using Computer and Modeling of Finite Elements

    Directory of Open Access Journals (Sweden)

    Masoumeh Khoshhal

    2016-03-01

    Full Text Available Introduction: Introduction: Few studies have investigated the distribution of stress around implants. In this study the distribution of stress in bones around implants was investigated in five overdenture (OD treatment designs including OD-1, OD-2, OD-3, OD-4 and OD-5. Materials and methods: The Catia modeling software was used in order to simulate the tooth/implant model and bone. First, the borders of cancellous and cortical bone in each section of the CT images were attained by Photoshop software. Then, modeling softwares SolidWorks and NUMBER were applied to make the final three-dimensional model of jaw. Finally, the amount of stress on the surface of bone/implant was studied by means of stress analysis software (Ansys v11.0. Results: Protrusive movements of implants B and D in OD-1 showed the highest amount of strain, 2435 εµ. Also, high amounts of strain, 1668 and 1557 εµwere observed in OD-1 and OD-2 designs in lateral movements respectively. Conclusion: The bottom line is that no forces to the extent of destruction based on the Ferost model were found for these designs. The highest amount of strain occurred in OD-1 design, which is held in mild overload window. Moreover, the amounts of strain in the rest of designs investigated were in adaptive window.

  3. Elementos tóxicos presentes em fosfatos, calcário e farinha de ossos Toxic Elements in phosphates, limestone and bone meal

    Directory of Open Access Journals (Sweden)

    Walter de Brito

    2011-09-01

    Full Text Available Objetivou-se identificar elementos tóxicos presentes nos seguintes produtos intensivamente utilizados na agropecuária brasileira: fosfato bicálcico, fosfato supertriplo, fosfato supersimples, fosfato monoamônico, fosfosulfato de amônio, polifosfato de cálcio e amônio, sal mineral bovino artesanal, farinha de ossos e calcário. Para a detecção dos elementos tóxicos utilizou-se as técnicas de difratometria de raios-x, absorção atômica de forno de grafite, colorimetria, gravimetria e ativação neutrônica. Foram detectados diversos elementos tóxicos, assim classificados conforme a agência norte americana de registro de substâncias tóxicas e doença relacionadas - ATSDR (Agency for Toxic Substances and Disease Registry como alumínio, arsênio, bário, cério, césio, cobalto, flúor, estrôncio, tório, urânio, vanádio e zinco . Também foram observadas elevadas concentrações de silício na forma de quartzo na farinha de ossos e no sal mineral bovino. O fosfato bicálcico é o produto que apresenta a menor presença de elementos tóxicos. Summary: This study aimed to identify toxic elements present in products largely used in Brazilian agriculture and livestock: dicalcium phosphate, super-triple phosphate, super-simple phosphate, monoammonium phosphate, sulphur amonium phoshphate, ammoniated calcium polyphosphate, a farm-made bovine mineral supplement, a bone meal and a limestone. Many techniques were employed in such analyses: X-ray diffractometry, atomic absorption, colorimetric and gravimetric techniques and instrumental neutron activation. It was detected many elements classified as hazard and toxic elements by the (United States ASTDR - Agency for Toxic Substances and Disease Registry such as Al, As, Ba, Ce, Cs, Co, F, Sr, Th, U, V e Zn. It has also noted a high presence of Si as quartz in the bone meal and in the bovine mineral supplement. Bicalcic phosphate presents the smallest presence of hazardous elements. Palavras

  4. Planning of excavation of seams characterized by complicated structure with the aim of coal mixing

    Energy Technology Data Exchange (ETDEWEB)

    Belyakov, Yu.I.; Pushkin, S.P. (Kievskii Inzhenerno-Stroitel' nyi Institut (USSR))

    1990-07-01

    Discusses use of mathematical modeling for optimization of surface mining in mines with a complicated coal deposit structure and changing coal quality. The modeling is aimed at stabilizing coal quality, especially ash content. Surface mines with bucket wheel excavators for overburden removal and mining and locomotives and railroad cars for mine haulage are modeled. The mines supply 2 classes of coal: with 47% ash and with 55%. The modeling is aimed at determining optimum advance rates of the bucket wheel excavators. Effects of mine haulage system, coal yard capacity, coal seam structure, fluctuations of coal quality in a coal deposit, requirements for optimum geometry of the working faces, benches and other elements that influence slope stability are considered. 2 refs.

  5. New excavations at the hypogeal necropolis of Sa Figu (Ittiri-Sassari: Tomb IV

    Directory of Open Access Journals (Sweden)

    Paolo Melis

    2010-07-01

    Full Text Available This paper presents the results of excavation in the 4th Tomb belonging the Bronze Age necropolis of Sa Figu, near Ittiri (Sassari-Sardinia: a rock-cut tomb of the "architectonic prospect" type, reproducing the characteristic elements of the nuragic "giant's tomb". Archaeological excavation has confirmed the chronology of these tombs, during the first phase of Middle Bronze Age (named "Sa Turricula", according with the dating of similar megalithic tombs. Iron Age re-use of this tomb are also detected, explaining some aspects of the burial context in the final phase of Nuragic civilization. It is clear, also, that the rock-cut tombs with architectonic prospect proceed from the megalithic model of the giant's tomb and find their origins in the "domus de janas" tombs of Neolithic.

  6. Application of supporting structure combining with basement slab in soft soil excavations engineering

    Science.gov (United States)

    Xiao, Rencheng; Liu, Le

    2017-05-01

    In this paper, based on the case of a soft soil excavations project in Zhongshan and the field measured data, the ABAQUS, a finite element software for engineering simulation, analyses the system which combines steel cement-soil pile and basement plate. Moreover it can simulate the deformation results and get the supporting stress model. The results show that the supporting effect of this system is remarkable. This simplified model calculation results are conservative. But there exists the problem of varying depth of excavations. As a result, the stress characteristics and design methods of the proposed scheme are less studied and need further research and discussion. The analysis method and the design scheme can provide useful reference for similar projects.

  7. Evaluation of the effect of the residual bone angulation on implant-supported fixed prosthesis in mandibular posterior edentulism. Part II: 3-D finite element stress analysis.

    Science.gov (United States)

    Akça, K; Iplikçioğlu, H

    2001-01-01

    Buccolingual angulation of the mandibular posterior edentulous region may affect the prosthetic load conditions, so as to cause high stress concentrated areas that may easily lead to failure. The aim of this study was to evaluate the effect of various predetermined buccolingual angulation values on stress distribution in the mandibular posterior edentulous region restored with implant-supported fixed partial dentures, using three-dimensional finite element analysis. Stress analyses were performed applying 400N oblique force to implant-supported fixed prosthesis. Stress analyses indicated tensile stress values on the buccal surface and compressive stress values on the lingual surface of cortical bone were increased as the angulation of the edentulous bone increased (especially corresponding to the cervical region of the implants). Compressive stress values, observed where two implants were placed at the second premolar and second molar regions (5-7 design) and first and second molar regions (6-7 design), respectively, were very close to or even exceeded the ultimate compressive strength of bone. It is concluded that when a definite buccolingual angulation is added to other existing risk factors such as bruxism, placing an implant for every missing tooth might reduce the high stress concentration areas.

  8. A poroelastic finite element model of the bone-cartilage unit to determine the effects of changes in permeability with osteoarthritis.

    Science.gov (United States)

    Stender, Michael E; Regueiro, Richard A; Ferguson, Virginia L

    2017-02-01

    The changes experienced in synovial joints with osteoarthritis involve coupled chemical, biological, and mechanical processes. The aim of this study was to investigate the consequences of increasing permeability in articular cartilage (AC), calcified cartilage (CC), subchondral cortical bone (SCB), and subchondral trabecular bone (STB) as observed with osteoarthritis. Two poroelastic finite element models were developed using a depth-dependent anisotropic model of AC with strain-dependent permeability and poroelastic models of calcified tissues (CC, SCB, and STB). The first model simulated a bone-cartilage unit (BCU) in uniaxial unconfined compression, while the second model simulated spherical indentation of the AC surface. Results indicate that the permeability of AC is the primary determinant of the BCU's poromechanical response while the permeability of calcified tissues exerts no appreciable effect on the force-indentation response of the BCU. In spherical indentation simulations with osteoarthritic permeability properties, fluid velocities were larger in magnitude and distributed over a smaller area compared to normal tissues. In vivo, this phenomenon would likely lead to chondrocyte death, tissue remodeling, alterations in joint lubrication, and the progression of osteoarthritis. For osteoarthritic and normal tissue permeability values, fluid flow was predicted to occur across the osteochondral interface. These results help elucidate the consequences of increases in the permeability of the BCU that occur with osteoarthritis. Furthermore, this study may guide future treatments to counteract osteoarthritis.

  9. Numerical Simulation of Blast Vibration and Crack Forming Effect of Rock-Anchored Beam Excavation in Deep Underground Caverns

    Directory of Open Access Journals (Sweden)

    XinPing Li

    2017-01-01

    Full Text Available Aiming at surrounding rock damage induced by dynamic disturbance from blasting excavation of rock-anchored beam in rock mass at moderate or far distance in underground cavern, numerical model of different linear charging density and crustal stress in underground cavern is established by adopting dynamic finite element software based on borehole layout, charging, and rock parameter of the actual situation of a certain hydropower station. Through comparison in vibration velocity, contour surface of rock mass excavation, and the crushing extent of excavated rock mass between calculation result and field monitoring, optimum linear charging density of blast hole is determined. Studies are also conducted on rock mass vibration in moderate or far distance to blasting source, the damage of surrounding rock in near-field to blasting source, and crushing degree of excavated rock mass under various in situ stress conditions. Results indicate that, within certain range of in situ stress, the blasting vibration is independent of in situ stress, while when in situ stress is increasing above certain value, the blasting vibration velocity will be increasing and the damage of surrounding rock and the crushing degree of excavated rock mass will be decreasing.

  10. Study of bone remodeling of two models of femoral cementless stems by means of DEXA and finite elements

    Directory of Open Access Journals (Sweden)

    López-Prats Fernando

    2010-05-01

    Full Text Available Abstract Background A hip replacement with a cemented or cementless femoral stem produces an effect on the bone called adaptive remodelling, attributable to mechanical and biological factors. All of the cementless prostheses designs try to achieve an optimal load transfer in order to avoid stress-shielding, which produces an osteopenia. Long-term densitometric studies taken after implanting ABG-I and ABG-II stems confirm that the changes made to the design and alloy of the ABG-II stem help produce less proximal atrophy of the femur. The simulation with FE allowed us to study the biomechanical behaviour of two stems. The aim of this study was, if possible, to correlate the biological and mechanical findings. Methods Both models with prostheses ABG-I and II have been simulated in five different moments of time which coincide with the DEXA measurements: postoperative, 6 months, 1, 3 and 5 years, in addition to the healthy femur as the initial reference. For the complete comparative analysis of both stems, all of the possible combinations of bone mass (group I and group II of pacients in two controlled studies for ABG-I and II stems, respectively, prosthetic geometry (ABG-I and ABG-II and stem material (Wrought Titanium or TMZF were simulated. Results and Discussion In both groups of bone mass an increase of stress in the area of the cancellous bone is produced, which coincides with the end of the HA coating, as a consequence of the bottleneck effect which is produced in the transmission of loads, and corresponds to Gruen zones 2 and 6, where no osteopenia can be seen in contrast to zones 1 and 7. Conclusions In this study it is shown that the ABG-II stem is more effective than the ABG-I given that it generates higher tensional values on the bone, due to which proximal bone atrophy diminishes. This biomechanical behaviour with an improved transmission of loads confirmed by means of FE simulation corresponds to the biological findings obtained with

  11. Stress distribution in fixed-partial prosthesis and peri-implant bone tissue with different framework materials and vertical misfit levels: a three-dimensional finite element analysis.

    Science.gov (United States)

    Bacchi, Ataís; Consani, Rafael L X; Mesquita, Marcelo F; dos Santos, Mateus B F

    2013-09-01

    The purpose of this study was to evaluate the influence of superstructure material and vertical misfits on the stresses created in an implant-supported partial prosthesis. A three-dimensional (3-D) finite element model was prepared based on common clinical data. The posterior part of a severely resorbed jaw with two osseointegrated implants at the second premolar and second molar regions was modeled using specific modeling software (SolidWorks 2010). Finite element models were created by importing the solid model into mechanical simulation software (ANSYS Workbench 11). The models were divided into groups according to the prosthesis framework material (type IV gold alloy, silver-palladium alloy, commercially pure titanium, cobalt-chromium alloy, or zirconia) and vertical misfit level (10 µm, 50 µm, and 100 µm) created at one implant-prosthesis interface. The gap of the vertical misfit was set to be closed and the stress values were measured in the framework, porcelain veneer, retention screw, and bone tissue. Stiffer materials led to higher stress concentration in the framework and increased stress values in the retention screw, while in the same circumstances, the porcelain veneer showed lower stress values, and there was no significant difference in stress in the peri-implant bone tissue. A considerable increase in stress concentration was observed in all the structures evaluated within the misfit amplification. The framework material influenced the stress concentration in the prosthetic structures and retention screw, but not that in bone tissue. All the structures were significantly influenced by the increase in the misfit levels.

  12. A Patient Specific Biomechanical Analysis of Custom Root Analogue Implant Designs on Alveolar Bone Stress: A Finite Element Study

    Directory of Open Access Journals (Sweden)

    David Anssari Moin

    2016-01-01

    Full Text Available Objectives. The aim of this study was to analyse by means of FEA the influence of 5 custom RAI designs on stress distribution of peri-implant bone and to evaluate the impact on microdisplacement for a specific patient case. Materials and Methods. A 3D surface model of a RAI for the upper right canine was constructed from the cone beam computed tomography data of one patient. Subsequently, five (targeted press-fit design modification FE models with five congruent bone models were designed: “Standard,” “Prism,” “Fins,” “Plug,” and “Bulbs,” respectively. Preprocessor software was applied to mesh the models. Two loads were applied: an oblique force (300 N and a vertical force (150 N. Analysis was performed to evaluate stress distributions and deformed contact separation at the peri-implant region. Results. The lowest von Mises stress levels were numerically observed for the Plug design. The lowest levels of contact separation were measured in the Fins model followed by the Bulbs design. Conclusions. Within the limitations of the applied methodology, adding targeted press-fit geometry to the RAI standard design will have a positive effect on stress distribution, lower concentration of bone stress, and will provide a better primary stability for this patient specific case.

  13. Screw angulation affects bone-screw stresses and bone graft load sharing in anterior cervical corpectomy fusion with a rigid screw-plate construct: a finite element model study.

    Science.gov (United States)

    Hussain, Mozammil; Natarajan, Raghu N; Fayyazi, Amir H; Braaksma, Brian R; Andersson, Gunnar B J; An, Howard S

    2009-12-01

    Anterior corpectomy and reconstruction with bone graft and a rigid screw-plate construct is an established procedure for treatment of cervical neural compression. Despite its reliability in relieving symptoms, there is a high rate of construct failure, especially in multilevel cases. There has been no study evaluating the biomechanical effects of screw angulation on construct stability; this study investigates the C4-C7 construct stability and load-sharing properties among varying screw angulations in a rigid plate-screw construct. A finite element model of a two-level cervical corpectomy with static anterior cervical plate. A three-dimensional finite element (FE) model of an intact C3-T1 segment was developed and validated. From this intact model, a fusion model (two-level [C5, C6] anterior corpectomy) was developed and validated. After corpectomy, allograft interbody fusion with a rigid anterior screw-plate construct was created from C4 to C7. Five additional FE models were developed from the fusion model corresponding to five different combinations of screw angulations within the vertebral bodies (C4, C7): (0 degrees, 0 degrees), (5 degrees, 5 degrees), (10 degrees, 10 degrees), (15 degrees, 15 degrees), and (15 degrees, 0 degrees). The fifth fusion model was termed as a hybrid fusion model. The stability of a two-level corpectomy reconstruction is not dependent on the position of the screws. Despite the locked screw-plate interface, some degree of load sharing is transmitted to the graft. The load seen by the graft and the shear stress at the bone-screw junction is dependent on the angle of the screws with respect to the end plate. Higher stresses are seen at more divergent angles, particularly at the lower level of the construct. This study suggests that screw divergence from the end plates not only increases load transmission to the graft but also predisposes the screws to higher shear forces after corpectomy reconstruction. In particular, the inferior screw

  14. Reducing Extra-Terrestrial Excavation Forces with Percussion

    Science.gov (United States)

    Schuler, Jason; Mueller, Robert; Smith, Drew; Nick, Andrew; Lippitt, Thomas

    2012-01-01

    High launch costs and mission requirements drive the need for low mass excavators with mobility platforms, which in turn have little traction and excavation reaction capacity in low gravity environments. This presents the need for precursor and long term future missions with low mass robotic mining technology to perform In-Situ Resource Utilization (ISRU) tasks. This paper discusses a series of experiments that investigate the effectiveness of a percussive digging device to reduce excavation loads and thereby the mass of the excavator itself. The goal of percussive excavation is to fluidize dry regolith in front of the leading edge of the tool by mechanically separating the microscopic interlocking grains resulting in a reduced force needed to shear the soil. There are several variables involved with this technique; this experiment varied: Impact energy, frequency, and excavation speed and held constant: impact direction, depth of cut, angle of tool, and soil bulk density. The test apparatus consisted of an aluminum truss bridge with a central pivoting arm. Attached to the arm was a winch with a load cell in line that recorded the tension in the cable and therefore the excavation load. The arm could be adjusted for excavation depth which was recorded along with the arm angle relative to the bridge. A percussive mechanism and 30" wide pivoting bucket were attached at the end of the arm simulating a basic backhoe with a percussion direction tangent to the direction of . movement. Internally the mechanism used a set of die springs and barrel cam to produce the percussive blow. By changing the springs and the speed of the motor the impact energy and frequency of percussion could be varied independently. Impact energies from 11.2J to 30.5J and frequencies from 0 BPM to 700 BPM were investigated. A reduction in excavation force of as much as 51% was achieved in this experimental investigation. Smaller percussive digging implements, tested by others, have achieved a

  15. Identification Schemes for Unmanned Excavator Arm Parameters

    Institute of Scientific and Technical Information of China (English)

    Yahya H. Zweiri

    2008-01-01

    Parameter identification is a key requirement in the field of automated control of unmanned excavators (UEs). Furthermore, the UE operates in unstructured, often hazardous environments, and requires a robust parameter identification scheme for field applications. This paper presents the results of a research study on parameter identification for UE. Three identification methods, the Newton-Raphson method, the generalized Newton method, and the least squares method are used and compared for prediction accuracy, robustness to noise and computational speed. The techniques are used to identify the link parameters (mass, inertia, and length) and friction coefficients of the full-scale UE. Using experimental data from a full-scale field UE, the values of link parameters and the friction coefficient are identified. Some of the identified parameters are compared with measured physical values. Furthermore, the joint torques and positions computed by the proposed model using the identified parameters are validated against measured data. The comparison shows that both the Newton-Raphson method and the generalized Newton method are better in terms of prediction accuracy. The Newton-Raphson method is computationally efficient and has potential for real time application, but the generalized Newton method is slightly more robust to measurement noise. The experimental data were obtained in collaboration with QinetiQ Ltd.

  16. Collisional Excavation of Asteroid (596) Scheila

    CERN Document Server

    Bodewits, D; Li, J -Y; Landsman, W B; Besse, S; A'Hearn, M F

    2011-01-01

    We observed asteroid (596) Scheila and its ejecta cloud using the Swift UV-optical telescope. We obtained photometry of the nucleus and the ejecta, and for the first time measured the asteroid's reflection spectrum between 290 - 500 nm. Our measurements indicate significant reddening at UV wavelengths (13% per 1000 {\\AA}) and a possible broad, unidentified absorption feature around 380 nm. Our measurements indicate that the outburst has not permanently increased the asteroid's brightness. We did not detect any of the gases that are typically associated with either hypervolatile activity thought responsible for cometary outbursts (CO+, CO2+), or for any volatiles excavated with the dust (OH, NH, CN, C2, C3). We estimate that 6 x 10^8 kg of dust was released with a high ejection velocity of 57 m/s (assuming 1 {\\mu}m sized particles). While the asteroid is red in color and the ejecta have the same color as the Sun, we suggest that the dust does not contain any ice. Based on our observations, we conclude that (59...

  17. Rock mass characterisation and stability analyses of excavated slopes

    Science.gov (United States)

    Zangerl, Christian; Lechner, Heidrun

    2016-04-01

    Excavated slopes in fractured rock masses are frequently designed for open pit mining, quarries, buildings, highways, railway lines, and canals. These slopes can reach heights of several hundreds of metres and in cases concerning open pit mines slopes larger than 1000 m are not uncommon. Given that deep-seated slope failures can cause large damage or even loss of life, the slope design needs to incorporate sufficient stability. Thus, slope design methods based on comprehensive approaches need to be applied. Excavation changes slope angle, groundwater flow, and blasting increases the degree of rock mass fracturing as well as rock mass disturbance. As such, excavation leads to considerable stress changes in the slopes. Generally, slope design rely on the concept of factor of safety (FOS), often a requirement by international or national standards. A limitation of the factor of safety is that time dependent failure processes, stress-strain relationships, and the impact of rock mass strain and displacement are not considered. Usually, there is a difficulty to estimate the strength of the rock mass, which in turn is controlled by an interaction of intact rock and discontinuity strength. In addition, knowledge about in-situ stresses for the failure criterion is essential. Thus, the estimation of the state of stress of the slope and the strength parameters of the rock mass is still challenging. Given that, large-scale in-situ testing is difficult and costly, back-calculations of case studies in similar rock types or rock mass classification systems are usually the methods of choice. Concerning back-calculations, often a detailed and standardised documentation is missing, and a direct applicability to new projects is not always given. Concerning rock mass classification systems, it is difficult to consider rock mass anisotropy and thus the empirical estimation of the strength properties possesses high uncertainty. In the framework of this study an approach based on

  18. Radionuclides and trace elements in fish collected upstream and downstream of Los Alamos National Laboratory and the doses to humans from the consumption of muscle and bone.

    Science.gov (United States)

    Fresquez, P R; Kraig, D H; Mullen, M A; Naranjo, L

    1999-09-01

    The purpose of this study was to determine radionuclide and trace element concentrations in bottom-feeding fish (catfish, carp, and suckers) collected from the confluences of some of the major canyons that cross Los Alamos National Laboratory (LANL) lands with the Rio Grande (RG) and the potential radiological doses from the ingestion of these fish. Samples of muscle and bone (and viscera in some cases) were analyzed for 3H, 90Sr, 137Cs, totU, 238Pu, 239,240Pu, and 241Am and Ag, As, Ba, Be, Cr, Cd, Cu, Hg, Ni, Pb, Sb, Se, and Tl. Most radionuclides, with the exception of 90Sr, in the muscle plus bone portions of fish collected from LANL canyons/RG were not significantly (p < 0.05) higher from fish collected upstream (San Ildefonso/background) of LANL. Strontium-90 in fish muscle plus bone tissue significantly (p < 0.05) increases in concentration starting from Los Alamos Canyon, the most upstream confluence (fish contained 3.4E-02 pCi g-1 [126E-02 Bq kg-1]), to Frijoles Canyon, the most downstream confluence (fish contained 14E-02 pCi g-1 [518E-02 Bq kg-1]). The differences in 90Sr concentrations in fish collected downstream and upstream (background) of LANL, however, were very small. Based on the average concentrations (+/- 2SD) of radionuclides in fish tissue from the four LANL confluences, the committed effective dose equivalent from the ingestion of 46 lb (21 kg) (maximum ingestion rate per person per year) of fish muscle plus bone, after the subtraction of background, was 0.1 +/- 0.1 mrem y-1 (1.0 +/- 1.0 microSv y-1), and was far below the International Commission on Radiological Protection (all pathway) permissible dose limit of 100 mrem y-1 (1000 microSv y-1). Of the trace elements that were found above the limits of detection (Ba, Cu, and Hg) in fish muscle collected from the confluences of canyons that cross LANL and the RG, none were in significantly higher (p < 0.05) concentrations than in muscle of fish collected from background locations.

  19. Optimization design of foundation excavation for Xiluodu super-high arch dam in China

    Institute of Scientific and Technical Information of China (English)

    Qixiang Fan; Shaowu Zhou; Ning Yang

    2015-01-01

    With better understanding of the quality and physico-mechanical properties of rocks of dam foundation, and the physico-mechanical properties and structure design of arch dam in association with the foun-dation excavation of Xiluodu arch dam, the excavation optimization design was proposed for the foundation surface on the basis of feasibility study. Common analysis and numerical analysis results demonstrated the feasibility of using the weakly weathered rocks III1 and III2 as the foundation surface of super-high arch dam. In view of changes in the geological conditions at the dam foundation along the riverbed direction, the design of extending foundation surface excavation area and using consolidating grouting and optimizing structure of dam bottom was introduced, allowing for harmonization of the arch dam and foundation. Three-dimensional (3D) geomechanics model test and finite element analysis re-sults indicated that the dam body and foundation have good overload stability and high bearing capacity. The monitoring data showed that the behaviors of dam and foundation correspond with the designed patterns in the construction period and the initial operation period.

  20. Optimization design of foundation excavation for Xiluodu super-high arch dam in China

    Directory of Open Access Journals (Sweden)

    Qixiang Fan

    2015-04-01

    Full Text Available With better understanding of the quality and physico-mechanical properties of rocks of dam foundation, and the physico-mechanical properties and structure design of arch dam in association with the foundation excavation of Xiluodu arch dam, the excavation optimization design was proposed for the foundation surface on the basis of feasibility study. Common analysis and numerical analysis results demonstrated the feasibility of using the weakly weathered rocks III1 and III2 as the foundation surface of super-high arch dam. In view of changes in the geological conditions at the dam foundation along the riverbed direction, the design of extending foundation surface excavation area and using consolidating grouting and optimizing structure of dam bottom was introduced, allowing for harmonization of the arch dam and foundation. Three-dimensional (3D geomechanics model test and finite element analysis results indicated that the dam body and foundation have good overload stability and high bearing capacity. The monitoring data showed that the behaviors of dam and foundation correspond with the designed patterns in the construction period and the initial operation period.

  1. Theoretical Analysis on the Effect of Tunnel Excavation on Building strip foundation

    Science.gov (United States)

    Tian, Xiaoyan; Gu, Shuancheng; Huang, Rongbin

    2017-09-01

    In this paper, according to the characteristics of the ground settlement troughs curves, the influence of tunnel excavation on the effect of strip foundation was studied by inverse analysis firstly. The differential equation of the synergistic effect of the strip foundation and foundation under the tunnel excavation was established by using the equilibrium condition of the micro-element physical force. Then, the conceptual definite initial parameter method was used to solve the corresponding homogeneous equation. According to the plane section assumption, combined with the basic theory of material mechanics, considering the differential characteristic of hyperbolic trigonometric function, and using matlabmathmatica software, the theoretical calculation expression of displacement and internal force which is about the tunnel passes through the strip foundation was obtained. Finally, combined with engineering case analysis, changes of the relative position between the tunnel and the foundation, the influences of the main parameters on the foundation effect were studied. The results show that: The influence scope of the tunnel on the foundation is [-0.5 ~ 1.5] times of the foundation length, and when the tunnel center at the end of the foundation, there exists the maximum settlement. The parameters about the soil loss rate, the excavation section and the buried depth of the tunnel have great influence on the foundation effect. The change of foundation height has a great influence on its internal force.

  2. Excavation of the Shell Mound at Damaoshan in Dongshan County,Fujian%福建东山县大帽山贝丘遗址的发掘

    Institute of Scientific and Technical Information of China (English)

    福建博物院; 美国哈佛大学人类学系

    2003-01-01

    To study prehistoric Fujian-Taiwan cultural relationship and other subjects,the Dongshan Damaoshan shell mound was excavated in November-December 2002.The objects unearthed include stone implements,jades,bone and shell artifacts and pottery,as well as plentiful remains of terrestrial and marine vertebrates and marine shellfish.The excavation not only clarified the date,nature,cultural contents and economic formation of the site,but also provided a scale for comparative studies of cultures in the Fujian and Taiwan regions and for establishing the chronological sequence of Neolithic cultures in southern Fujian.

  3. 山东济宁市玉皇顶遗址发掘简报%Excavation on the Yuhuangding Site in Jining City, Shandong

    Institute of Scientific and Technical Information of China (English)

    济宁市文物考古研究室; 济宁市任城区文物管理所

    2005-01-01

    In 1996, the Jining Municipal Institute of Cultural Relics and Archaeology and another institution carried out a rescuing excavation on the Yuhuangding site. In the excavated area of about 80 sq m they revealed Neolithic house-foundations and ash pits and Shang period ash-pits and wells, as well as Neolithic pottery and stone tools and Shang pottery and bone artifacts. The Neolithic remains are similar to those of the Yanzhou Wangyin site, and date roughly from the late Beixin culture to the early Dawenkou culture. The Shang cultural remains correspond in date to the Jining Fenghuangtai and Panmiao sites, belonging roughly to Phase I of the Yinxu culture.

  4. Excavation in the Gangouzi Cemetery in Changbai County,Jilin%吉林长白县干沟子墓地发掘简报

    Institute of Scientific and Technical Information of China (English)

    吉林省文物考古研究所

    2003-01-01

    In May~July 2001, the Jilin Provincial Institute of Cultural Relics and Archaeologysurveyed the Gangouzi cemetery in Changbai County and excavated there seven tombs. These are stoneburial pits each with several or dozen circular, semicircular or fan-like platforms structured of pebbles andconnected with each other. They contain secondary burials after cremation. Human bones are largelybroken. The funeral objects consist of pottery, jade and stone artifacts and bronzes. The excavation is ofimportant value to studying the origin of the tomb shape prevailing among the Kaoguryo people.

  5. Impact-Actuated Digging Tool for Lunar Excavation Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Honeybee Robotics proposes to develop a vacuum compatible, impact-actuated digging tool for the excavation of frozen and compacted regolith on the lunar surface and...

  6. MPED: An ISRU Bucket Ladder Excavator Demonstrator System Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The proposed innovation is a planetary surface tool called the Multi Purpose Excavation Demonstrator (MPED), which is intended to both extract Lunar Soil to feed an...

  7. Telerobotic Excavator Designed to Compete in NASA's Lunabotics Mining Competition

    Science.gov (United States)

    Nash, Rodney; Santin, Cara; Yousef, Ahmed; Nguyen, Thien; Helferty, John; Pillapakkam, Shriram

    2011-01-01

    The second annual NASA Lunabotics Mining competition is to be held in May 23-28, 2011. The goal of the competition is for teams of university level students to design, build, test and compete with a fully integrated lunar excavator on a simulated lunar surface. Our team, named Lunar Solutions I, will be representing Temple University's College of Engineering in the competition. The team's main goal was to build a robot which is able to compete with other teams, and ultimately win the competition. The main challenge of the competition was to build a wireless robot that can excavate and collect a minimum of 10 kilograms of the regolith material within 15 minutes. The robot must also be designed to operate in conditions similar to those found on the lunar surface. The design of the lunar excavator is constrained by a set of requirements determined by NASA and detailed in the competition's rulebook. The excavator must have the ability to communicate with the "main base" wirelessly, and over a Wi-Fi network. Human operators are located at a remote site approximately 60 meters away from the simulated lunar surface upon which the robot must excavate the lunar regolith surface. During the competition, the robot will operate in a separate area from the control room in an area referred to as the "Lunarena." From the control room, the operators will have to control the robot using visual feedback from cameras placed both within the arena and on the robot. Using this visual feedback the human operators control the robots movement using both keyboard and joystick commands. In order to place in the competition, a minimum of 10 kg of regolith material has to be excavated, collected, and dumped into a specific location. For that reason, the robot must be provided with an effective and powerful excavation system. Our excavator uses tracks for the drive system. After performing extensive research and trade studies, we concluded that tracks would be the most effective method for

  8. ROCK MASS DAMAGED ZONE CAUSED BY BLASTING DURING TUNNEL EXCAVATION

    OpenAIRE

    Hrvoje Antičević; Mario Dobrilović; Hrvoje Perković

    2012-01-01

    Design of underground spaces, including tunnels, and repositories for radioactive waste include the application of the same or similar technologies. Tunnel excavation by blasting inevitably results in the damage in the rock mass around the excavation profile. The damage in the rock mass immediately next to the tunnel profile emerges as the expanding of the existing cracks and the appearance of new cracks, i.e. as the change of the physical and-mechanical properties of the rock mass. Concernin...

  9. Greenhouse Gas Emissions from Excavation on Residential Construction Sites

    OpenAIRE

    Perry Forsythe; Grace Ding

    2014-01-01

    Despite considerable research concerning the manifestation of greenhouse gases in the usage of buildings, little has been done concerning emissions arising from the construction process itself. This paper specifically examines emissions arising from cut and fill excavation on residential construction sites. Even though such excavation is often seen as being economical in terms of providing a flat base for concrete raft slab construction, the environmental consequences of this approach need to...

  10. Combination of Fault Tree and Neural Networks in Excavator Diagnosis

    OpenAIRE

    Li Guoping; Zhang Qingwei; Ma Xiao

    2013-01-01

    By using the theory of artificial intelligence fault diagnosis of hydraulic excavator of several basic problems are discussed in this paper, the artificial intelligence neural network model is established for the fault diagnosis of hydraulic system; the combined application of fault diagnosis analysis (FTA) and artificial neural network is evaluated. In view of the hydraulic excavator failure symptom of dispersion and fuzziness, the fault diagnosis method was presented based on the fault tree...

  11. Effect of ground motion from nuclear excavation: interim canal studies

    Energy Technology Data Exchange (ETDEWEB)

    King, C. Y.; Nadolski, M. E.

    1969-09-01

    The effect of ground motion due to nuclear excavation of a sea-level canal at two alternative routes, 17A and 25E, are discussed from the aspects of motion prediction and structural response. The importance of the high-rise building problem is stressed because of its complexity. Several damage criteria are summarized for advance planning of excavation and operation. The 1964 shot schedule and the latest revised schedule are included for comparison.

  12. NOVEL EXCAVATION TECHNOLOGIES FOR EFFICIENT AND ECONOMIC SURFACE MINING

    Energy Technology Data Exchange (ETDEWEB)

    Vladislav Kecojevic; Samuel Frimpong

    2005-05-01

    Ground excavation constitutes a significant component of production costs in any surface mining operation. The excavation process entails material digging and removal in which the equipment motion is constrained by the workspace geometry. A major excavation problem is the variability of material properties, resulting in varying mechanical energy input and stress loading of shovel dipper-and-tooth assembly across the working bench. This variability has a huge impact on the shovel dipper and tooth assembly in hard formations. With this in mind, the primary objectives of the project were to (i) provide the theoretical basis to develop the Intelligent Shovel Excavation (ISE) technology to solve the problems associated with excavation in material formations; (ii) advance knowledge and frontiers in shovel excavation through intelligent navigation; and (iii) submit proposal for the design, development and implementation of the ISE technology for shovel excavation at experimental surface mining sites. The mathematical methods were used to (i) develop shovel's kinematics and dynamics, and (ii) establish the relationship between shovel parameters and the resistive forces from the material formation during excavation process. The ADAMS simulation environment was used to develop the hydraulic and cable shovel virtual prototypes. Two numerical examples are included to test the theoretical hypotheses and the obtained results are discussed. The area of sensor technology was studied. Application of specific wrist-mounted sensors to characterize the material, bucket and frame assembly was determined. Data acquisition, display and control system for shovel loading technology was adopted. The concept of data acquisition and control system was designed and a shovel boom stresses were simulated. A multi-partner collaboration between research organizations, shovel manufacturer, hardware and sensor technology companies, and surface mining companies is proposed to test design

  13. Dam foundation excavation techniques in China:A review

    Institute of Scientific and Technical Information of China (English)

    Yuzhu Zhang; Wenbo Lu; Ming Chen; Peng Yan; Yingguo Hu

    2013-01-01

    A protective layer (PL) is commonly reserved above foundation surface to protect the underlying rock mass during dam foundation excavation. In China, the PL of dam foundation is conventionally subdivided into two or three thin layers and excavated with the shallow-hole blasting method, even by pneumatic pick method in case of soft rock mass. The aforementioned layered excavation of the PL delays the con-struction of the whole project. After nearly 30-year practices, several safe and efficient methods for the PL excavation of dam foundation are gradually developed. They include shallow-hole bench blasting with cushion material (SBC) at the bottom of the hole, and horizontal smooth blasting (HSB). The PL is even can-celled on the condition that horizontal pre-split technique is employed during dam foundation excavation. This paper introduces the aforementioned two PL excavation methods (shallow-hole blasting and bench blasting) and horizontal pre-split technique of dam foundation without protective layer (HPP). The basic principles of blasting method, blasting geometry, charge structure, drill-and-blast parameters of typical projects are examined. Meanwhile, the merits and limitations of each method are compared. Engineering practices in China show that HSB is basically the optimal method for dam foundation PL excavation in terms of foundation damage control and rapid construction. Some new problems for dam foundation PL excavation arising, such as strong unloading and relaxation phenomenon that encountered in the gorge region of southwest China, are needed to be addressed; and the corresponding countermeasures are discussed as well.

  14. Finite element modelling versus classic beam theory: comparing methods for stress estimation in a morphologically diverse sample of vertebrate long bones.

    Science.gov (United States)

    Brassey, Charlotte A; Margetts, Lee; Kitchener, Andrew C; Withers, Philip J; Manning, Phillip L; Sellers, William I

    2013-02-01

    Classic beam theory is frequently used in biomechanics to model the stress behaviour of vertebrate long bones, particularly when creating intraspecific scaling models. Although methodologically straightforward, classic beam theory requires complex irregular bones to be approximated as slender beams, and the errors associated with simplifying complex organic structures to such an extent are unknown. Alternative approaches, such as finite element analysis (FEA), while much more time-consuming to perform, require no such assumptions. This study compares the results obtained using classic beam theory with those from FEA to quantify the beam theory errors and to provide recommendations about when a full FEA is essential for reasonable biomechanical predictions. High-resolution computed tomographic scans of eight vertebrate long bones were used to calculate diaphyseal stress owing to various loading regimes. Under compression, FEA values of minimum principal stress (σ(min)) were on average 142 per cent (±28% s.e.) larger than those predicted by beam theory, with deviation between the two models correlated to shaft curvature (two-tailed p = 0.03, r(2) = 0.56). Under bending, FEA values of maximum principal stress (σ(max)) and beam theory values differed on average by 12 per cent (±4% s.e.), with deviation between the models significantly correlated to cross-sectional asymmetry at midshaft (two-tailed p = 0.02, r(2) = 0.62). In torsion, assuming maximum stress values occurred at the location of minimum cortical thickness brought beam theory and FEA values closest in line, and in this case FEA values of τ(torsion) were on average 14 per cent (±5% s.e.) higher than beam theory. Therefore, FEA is the preferred modelling solution when estimates of absolute diaphyseal stress are required, although values calculated by beam theory for bending may be acceptable in some situations.

  15. Segmental acetabular rim defects, bone loss, oversizing, and press fit cup in total hip arthroplasty evaluated with a probabilistic finite element analysis.

    Science.gov (United States)

    Amirouche, Farid; Solitro, Giovanni F; Walia, Amit; Gonzalez, Mark; Bobko, Aimee

    2017-08-01

    Management of segmental rim defects and bone mineral density (BMD) loss in the elderly prior to total hip replacement is unclear within classification systems for acetabular bone loss. In this study, our objectives were (1) to understand how a reduction in BMD in the elderly affects the oversizing of a press-fit cup for primary fixation and (2) to evaluate whether the location of the segmental defect affected cup fixation. A finite element (FE) model was used to simulate and evaluate cup insertion and fixation in the context of segmental rim defects. We focused on the distribution of patients over age 70 and used BMD (estimated from CT) as a proxy for aging's implications on THR and used probabilistic FE analysis to understand how BMD loss affects oversizing of a press-fit cup. A cup oversized by 1.10 ± 0.28 mm provides sufficient fixation and lower stresses at the cup-bone interface for elderly patients. Defects in the anterior column and posterior column both required the same mean insertion force for cup seating of 84% (taken as an average of 2 anterior column and 2 posterior column defects) compared to the control configuration, which was 5% greater than the insertion force for a superior rim defect and 12% greater than the insertion force for an inferior rim defect. A defect along the superior or inferior rim had a minimal effect on cup fixation, while a defect in the columns created cup instability and increased stress at the defect location.

  16. In Vivo μMRI-Based Finite Element and Morphological Analyses of Tibial Trabecular Bone in Eugonadal and Hypogonadal Men Before and After Testosterone Treatment

    Science.gov (United States)

    Zhang, X Henry; Liu, X Sherry; Vasilic, Branimir; Wehrli, Felix W; Benito, Maria; Rajapakse, Chamith S; Snyder, Peter J; Guo, X Edward

    2008-01-01

    Osteoporosis is a major public health problem in men. Hypogonadal men have decreased BMD and deteriorated trabecular bone architecture compared with eugonadal men. Testosterone treatment improves their BMD and trabecular structure. We tested the hypothesis that testosterone replacement in hypogonadal men would also improve their bone's mechanical properties. Ten untreated severely hypogonadal and 10 eugonadal men were selected. The hypogonadal men were treated with a testosterone gel for 24 mo to maintain their serum testosterone concentrations within the normal range. Each subject was assessed before and after 6, 12, and 24 mo of testosterone treatment by μMRI of the distal tibia. A subvolume of each μMR image was converted to a microfinite element (μFE) model, and six analyses were performed, representing three compression and three shear tests. The anisotropic stiffness tensor was calculated, from which the orthotropic elastic material constants were derived. Changes in microarchitecture were also quantified using newly developed individual trabeculae segmentation (ITS)-based and standard morphological analyses. The accuracy of these techniques was examined with simulated μMR images. Significant differences in four estimated anisotropic elastic material constants and most morphological parameters were detected between the eugonadal and hypogonadal men. No significant change in estimated elastic moduli and morphological parameters was detected in the eugonadal group over 24 mo. After 24 mo of treatment, significant increases in estimated elastic moduli E22 (9.0%), E33 (5.1%), G23 (7.2%), and G12 (9.4%) of hypogonadal men were detected. These increases were accompanied by significant increases in trabecular plate thickness. These results suggest that 24 mo of testosterone treatment of hypogonadal men improves estimated elastic moduli of tibial trabecular bone by increased trabecular plate thickness. PMID:18410234

  17. Research on Trajectory Planning and Autodig of Hydraulic Excavator

    Directory of Open Access Journals (Sweden)

    Bin Zhang

    2017-01-01

    Full Text Available As the advances in computer control technology keep emerging, robotic hydraulic excavator becomes imperative. It can improve excavation accuracy and greatly reduce the operator’s labor intensity. The 12-ton backhoe bucket excavator has been utilized in this research work where this type of excavator is commonly used in engineering work. The kinematics model of operation device (boom, arm, bucket, and swing in excavator is established in both Denavit-Hartenberg coordinates for easy programming and geometric space for avoiding blind spot. The control approach is based on trajectory tracing method with displacements and velocities feedbacks. The trajectory planning and autodig program is written by Visual C++. By setting the bucket teeth’s trajectory, the program can automatically plan the velocity and acceleration of each hydraulic cylinder and motor. The results are displayed through a 3D entity simulation environment which can present real-time movements of excavator kinematics. Object-Oriented Graphics Rendering Engine and skeletal animation are used to give accurate parametric control and feedback. The simulation result shows that a stable linear autodig can be achieved. The errors between trajectory planning command and simulation model are analyzed.

  18. Motion Planning Based Coordinated Control for Hydraulic Excavators

    Institute of Scientific and Technical Information of China (English)

    GAO Yingjie; JIN Yanchao; ZHANG Qin

    2009-01-01

    Hydraulic excavator is one type of the most widely applied construction equipment for various applications mainly because of its versatility and mobility. Among the tasks performed by a hydraulic excavator, repeatable level digging or flat surface finishing may take a large percentage. Using automated functions to perform such repeatable and tedious jobs will not only greatly increase the overall productivity but more importantly also improve the operation safety. For the purpose of investigating the technology without loss of generality, this research is conducted to create a coordinate control method for the boom, arm and bucket cylinders on a hydraulic excavator to perform accurate and effective works. On the basis of the kinematic analysis of the excavator linkage system, the tip trajectory of the end-effector can be determined in terms of three hydraulic cylinders coordinated motion with a visualized method. The coordination of those hydraulic cylinders is realized by controlling three electro-hydranlic proportional valves coordinately. Therefore,the complex control algorithm of a hydraulic excavator can be simplified into coordinated motion control of three individual systems.This coordinate control algorithm was validated on a wheeled hydraulic excavator, and the validation results indicated that this developed control method could satisfaetorily accomplish the auto-digging function for level digging or flat surface finishing.

  19. Greenhouse Gas Emissions from Excavation on Residential Construction Sites

    Directory of Open Access Journals (Sweden)

    Perry Forsythe

    2014-12-01

    Full Text Available Despite considerable research concerning the manifestation of greenhouse gases in the usage of buildings, little has been done concerning emissions arising from the construction process itself. This paper specifically examines emissions arising from cut and fill excavation on residential construction sites. Even though such excavation is often seen as being economical in terms of providing a flat base for concrete raft slab construction, the environmental consequences of this approach need to be considered more fully in terms of impact on the environment. This is particularly important when steeply sloping sites are involved and for different soil types. The paper undertakes a study that quantitatively assesses the cumulative greenhouse gas emissions caused by cut and fill excavation on 52 residential projects in Australia for a range of slope and soil types. The paper presents results from the study and concludes that greenhouse gas emissions increase as site slope increases; the building footprint area (as distinct from Gross Floor Area, exposes the need to reduce the area of the building to reduce greenhouse gas emissions; excavation of rock soils creates higher emissions than other soil types; and cut and fill excavation on steeply slope sites increase emissions. Potential alternative construction includes suspended floor construction systems which involve less excavation.

  20. Greenhouse Gas Emissions from Excavation on Residential Construction Sites

    Directory of Open Access Journals (Sweden)

    Perry Forsythe

    2014-12-01

    Full Text Available Despite considerable research concerning the manifestation of greenhouse gases in the usage of buildings, little has been done concerning emissions arising from the construction process itself. This paper specifically examines emissions arising from cut and fill excavation on residential construction sites. Even though such excavation is often seen as being economical in terms of providing a flat base for concrete raft slab construction, the environmental consequences of this approach need to be considered more fully in terms of impact on the environment. This is particularly important when steeply sloping sites are involved and for different soil types. The paper undertakes a study that quantitatively assesses the cumulative greenhouse gas emissions caused by cut and fill excavation on 52 residential projects in Australia for a range of slope and soil types. The paper presents results from the study and concludes that greenhouse gas emissions increase as site slope increases; the building footprint area (as distinct from Gross Floor Area, exposes the need to reduce the area of the building to reduce greenhouse gas emissions; excavation of rock soils creates higher emissions than other soil types; and cut and fill excavation on steeply slope sites increase emissions. Potential alternative construction includes suspended floor construction systems which involve less excavation

  1. Excavation on the Wuzhuang Site in Luyi County, Henan%河南鹿邑县武庄遗址的发掘

    Institute of Scientific and Technical Information of China (English)

    河南省文物考古研究所

    2002-01-01

    The Wuzhuang site lies north of Wuzhuang Village, Wangpiliu Township, Luyi County, Henan Province. Excavation there discovered Neolithic vestiges and objects. The cultural deposits can be divided into two phases, The remains of the first phase consist of house-foundations, ash-pits, ditches and other vestiges, which yielded mainly pottery, and also a number of animal bones and clamshells. The second phase is represented by ash-pits as well as plentiful artifacts, including pottery, stone, bone, horn and shell articles, and a large number of animal bones and clamshells. The latter was the development of the former. The site is the only rather early Neolithic settlement scientifically excavated so far in the eastern Henan area.

  2. Review of In Vivo Bone Strain Studies and Finite Element Models of the Zygomatic Complex in Humans and Nonhuman Primates: Implications for Clinical Research and Practice.

    Science.gov (United States)

    Prado, Felippe Bevilacqua; Freire, Alexandre Rodrigues; Cláudia Rossi, Ana; Ledogar, Justin A; Smith, Amanda L; Dechow, Paul C; Strait, David S; Voigt, Tilman; Ross, Callum F

    2016-12-01

    The craniofacial skeleton is often described in the clinical literature as being comprised of vertical bony pillars, which transmit forces from the toothrow to the neurocranium as axial compressive stresses, reinforced transversely by buttresses. Here, we review the literature on bony microarchitecture, in vivo bone strain, and finite-element modeling of the facial skeleton of humans and nonhuman primates to address questions regarding the structural and functional existence of facial pillars and buttresses. Available bone material properties data do not support the existence of pillars and buttresses in humans or Sapajus apella. Deformation regimes in the zygomatic complex emphasize bending and shear, therefore conceptualizing the zygomatic complex of humans or nonhuman primates as a pillar obscures its patterns of stress, strain, and deformation. Human fossil relatives and chimpanzees exhibit strain regimes corroborating the existence of a canine-frontal pillar, but the notion of a zygomatic pillar has no support. The emerging consensus on patterns of strain and deformation in finite element models (FEMs) of the human facial skeleton corroborates hypotheses in the clinical literature regarding zygomatic complex function, and provide new insights into patterns of failure of titanium and resorbable plates in experimental studies. It is suggested that the "pillar and buttress" model of human craniofacial skeleton function be replaced with FEMs that more accurately and precisely represent in vivo function, and which can serve as the basis for future research into implants used in restoration of occlusal function and fracture repair. Anat Rec, 299:1753-1778, 2016. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

  3. Heart rot hotel: fungal communities in red-cockaded woodpecker excavations

    Science.gov (United States)

    Michelle A. Jusino; Daniel L. Lindner; Mark T. Banik; Jeffrey R. Walters

    2015-01-01

    Tree-cavity excavators such as woodpeckers are ecosystem engineers that have potentially complex but poorly documented associations with wood decay fungi. Fungi facilitate cavity excavation by preparing and modifying excavation sites for cavity excavators. Associations between fungi and endangered red-cockaded woodpeckers (RCWs) are particularly interesting because...

  4. Deformation and failure mechanism of excavation in clay subjected to hydraulic uplift

    CERN Document Server

    Hong, Yi

    2016-01-01

    This book presents the latest experimental and numerical analysis work in the field of ground deformation and base instability of deep excavations in soft clay subjected to hydraulic uplift. The authors’ latest research findings, based on dimensional analyses, well-instrumented full-scale field tests, systematic coupled-consolidation finite element analyses and centrifuge tests are reported. This book shows how to systematically approach a complex geotechnical problem, from identifying existing problems, reviewing literature, to dimensional and numerical analyses, validation through full-scale testing and centrifuge model testing. The methodologies are also introduced as major tools adopted in geotechnical research.

  5. The influence of jet-grout constitutive modelling in excavation analyses

    OpenAIRE

    Ciantia, M.; Arroyo Alvarez de Toledo, Marcos; Castellanza, R; Gens Solé, Antonio

    2012-01-01

    A bonded elasto-plastic soil model is employed to characterize cement-treated clay in the finite element analysis of an excavation on soft clay supported with a soil-cement slab at the bottom. The soft clay is calibrated to represent the behaviour of Bangkok soft clay. A parametric study is run for a series of materials characterised by increasing cement content in the clay-cement mixture. The different mixtures are indirectly specified by means of their unconfined compressive strength. A ...

  6. Bone tumor

    Science.gov (United States)

    Tumor - bone; Bone cancer; Primary bone tumor; Secondary bone tumor; Bone tumor - benign ... The cause of bone tumors is unknown. They often occur in areas of the bone that grow rapidly. Possible causes include: Genetic defects ...

  7. A Survey of Commercially Available and Proven Remote Control Machines for Excavation and Recovery of Buried Ordnance

    Energy Technology Data Exchange (ETDEWEB)

    Pruneda, C; Bilstrom, A

    2002-03-01

    The issue of unexploded ordnance excavation and removal is complicated by the interaction between the independent robotics systems (e.g. manipulator, sensors, and software). A review of commercially available robotic systems highlights the specificity of the design and intent of each for the application and problem being addressed. Although multiple parties, including universities, research institutes, and manufacturers worldwide are concerned with removing explosive ordnance (EOD) and unexploded ordnance (UXO), the exact details of the problems and tasks at each site differ between projects, even slightly. The risks associated with the excavation and removal of ordnance require a level of robustness that necessitates extensive testing and engineering despite project similarities. Based on the experience of researchers, the integration of systems at unique excavation sites will be the critical element of the project to ensure the safe and robust removal of buried ordnance. Although this report touches on some systems integration issues to a limited degree, the report at this stage is primarily a survey of commercially available, proven robotics components and systems for the excavation and recovery of buried ordnance.

  8. Modelling of excavation depth and fractures in rock caused by tool indentation

    Energy Technology Data Exchange (ETDEWEB)

    Kou Shaoquan; Tan Xiangchun; Lindqvist, P.A. [Luleaa Univ. of Technology (Sweden)

    1997-10-01

    The hydraulic regime after excavation in the near-field rock around deposition holes and deposition tunnels in a spent nuclear fuel repository is of concern for prediction of the saturation process of bentonite buffer and tunnel backfill. The hydraulic condition of main interest in this context is a result of the fracture network that is caused by the excavation. Modelling of the excavation disturbed zone in hard rocks caused by mechanical excavation has been carried out in the Division of Mining Engineering since 1993. This report contains an overview of the work conducted. The mechanical excavation is reasonably simplified as an indentation process of the interaction between rigid indenters and rocks. A large number of experiments have been carried out in the laboratory, and the results used for identifying crushed zones and fracture systems in rock under indentation are presented based on these experiments. The indentation causes crushing and damage of the rock and results in a crushed zone and a cracked zone. The indenter penetrates the rock with a certain depth when the force is over a threshold value relevant to the rock and tool. Outside the cracked zone there are basically three systems of cracks: median cracks, radial cracks, and side cracks. Fully developed radial cracks on each side of the indented area can connect with each other and join with median crack. This forms the so-called radial/median crack system. The influence of the mechanical properties of the rock is discussed based on our conceptual model, and the main factors governing the indentation event are summarised. The cracked zone is dealt with by an analytical fracture model. The side crack is simulated by applying the boundary element method coupled with fracture mechanics. Functional relationships are established relating either the indentation depth or the length of radial/median cracks to the various quantities characterising the physical event, namely the shape and the size of the

  9. Addressing the Consequences of Dynamic Rock Failure in Underground Excavations

    Science.gov (United States)

    Stacey, T. R.

    2016-10-01

    Rockbursts are violent events that result in the ejection of volumes of rock from the walls of underground excavations. They can be extremely hazardous and have been responsible for many accidents in underground excavations. They also are responsible for significant direct and indirect costs in mining and civil engineering projects. The occurrence of rockbursting can be reduced by optimising the design with regard to excavation layout, excavation geometry and size, excavation sequence, and by the application of destressing/preconditioning measures. Thereafter, containment of damage relies on rock support. Conventional design of rock support for the containment of rockburst damage is not possible since neither the demand that is generated, nor the capacity of support systems, are known, and thus there is a state of design indeterminacy. The approach recommended in this paper is a risk-consequence one: evaluation of the risk (the product of the probability of occurrence of a rockburst and its consequence, in financial terms), and use of this quantified risk as a decision making tool regarding the justification for significant dynamically capable rock support. A typically suitable rock support system for rockbursting conditions is suggested in the paper.

  10. Monitoring of Deformation in Ground Before and After Tunnel Excavation

    Science.gov (United States)

    Eren, Mehmet; Hilmi Erkoç, Muharrem

    2017-04-01

    As population increase in metropolitan city, we need transportation and transmission tunnel. In this context, the engineers and administors attach impotance to building and planning underground-tunnel. Moreover, we must at regular intervals monitoring to deformation in underground-tunnel for quality and safety. Firstly, a deformation monitoring network is designed as perpendicular to the tunnel main axis. Secondly, the prescribed number of deformation measurements must be made. Finally, the deformation analysis is evaluated and its results is interpreted. This study investigates how deformation in monitoring network during and after tunnel excavate change.For this purpose, a deformation monitoring network of 18 object point and 4 reference point was established. Object points networks was designed steeply to the tunnel main axis as 3 cross section. Each cross section consisted of 3 point left, 2 point right and 1 point at the flowing line. Initial conditional measurement was made before tunnel excavation. Then the deformation measurement was made 5 period (1 period measured after tunnel excavate). All data sets were adjusted according to free adjustment method. The results from the investigation considering the tunnel line, a symmetrical subsidence was observed. The following day of tunnel excavation, we were observed %68 per of the total deformation. At the end of the last period measurements, %99 per of the total deformation was detected. Keywords: Tunnel, Deformation, Subsidence, Excavation

  11. Bone-breaking bite force of Basilosaurus isis (Mammalia, Cetacea from the late Eocene of Egypt estimated by finite element analysis.

    Directory of Open Access Journals (Sweden)

    Eric Snively

    Full Text Available Bite marks suggest that the late Eocence archaeocete whale Basilosaurus isis (Birket Qarun Formation, Egypt fed upon juveniles of the contemporary basilosaurid Dorudon atrox. Finite element analysis (FEA of a nearly complete adult cranium of B. isis enables estimates of its bite force and tests the animal's capabilities for crushing bone. Two loadcases reflect different biting scenarios: 1 an intitial closing phase, with all adductors active and a full condylar reaction force; and 2 a shearing phase, with the posterior temporalis active and minimized condylar force. The latter is considered probable when the jaws were nearly closed because the preserved jaws do not articulate as the molariform teeth come into occulusion. Reaction forces with all muscles active indicate that B. isis maintained relatively greater bite force anteriorly than seen in large crocodilians, and exerted a maximum bite force of at least 16,400 N at its upper P3. Under the shearing scenario with minimized condylar forces, tooth reaction forces could exceed 20,000 N despite lower magnitudes of muscle force. These bite forces at the teeth are consistent with bone indentations on Dorudon crania, reatract-and-shear hypotheses of Basilosaurus bite function, and seizure of prey by anterior teeth as proposed for other archaeocetes. The whale's bite forces match those estimated for pliosaurus when skull lengths are equalized, suggesting similar tradeoffs of bite function and hydrodynamics. Reaction forces in B. isis were lower than maxima estimated for large crocodylians and carnivorous dinosaurs. However, comparison of force estimates from FEA and regression data indicate that B. isis exerted the largest bite forces yet estimated for any mammal, and greater force than expected from its skull width. Cephalic feeding biomechanics of Basilosaurus isis are thus consistent with habitual predation.

  12. Excavation Equipment Recognition Based on Novel Acoustic Statistical Features.

    Science.gov (United States)

    Cao, Jiuwen; Wang, Wei; Wang, Jianzhong; Wang, Ruirong

    2016-09-30

    Excavation equipment recognition attracts increasing attentions in recent years due to its significance in underground pipeline network protection and civil construction management. In this paper, a novel classification algorithm based on acoustics processing is proposed for four representative excavation equipments. New acoustic statistical features, namely, the short frame energy ratio, concentration of spectrum amplitude ratio, truncated energy range, and interval of pulse are first developed to characterize acoustic signals. Then, probability density distributions of these acoustic features are analyzed and a novel classifier is presented. Experiments on real recorded acoustics of the four excavation devices are conducted to demonstrate the effectiveness of the proposed algorithm. Comparisons with two popular machine learning methods, support vector machine and extreme learning machine, combined with the popular linear prediction cepstral coefficients are provided to show the generalization capability of our method. A real surveillance system using our algorithm is developed and installed in a metro construction site for real-time recognition performance validation.

  13. A novel energy recovery system for parallel hybrid hydraulic excavator.

    Science.gov (United States)

    Li, Wei; Cao, Baoyu; Zhu, Zhencai; Chen, Guoan

    2014-01-01

    Hydraulic excavator energy saving is important to relieve source shortage and protect environment. This paper mainly discusses the energy saving for the hybrid hydraulic excavator. By analyzing the excess energy of three hydraulic cylinders in the conventional hydraulic excavator, a new boom potential energy recovery system is proposed. The mathematical models of the main components including boom cylinder, hydraulic motor, and hydraulic accumulator are built. The natural frequency of the proposed energy recovery system is calculated based on the mathematical models. Meanwhile, the simulation models of the proposed system and a conventional energy recovery system are built by AMESim software. The results show that the proposed system is more effective than the conventional energy saving system. At last, the main components of the proposed energy recovery system including accumulator and hydraulic motor are analyzed for improving the energy recovery efficiency. The measures to improve the energy recovery efficiency of the proposed system are presented.

  14. Development of Force Reflecting Joystick for Hydraulic Excavator

    Science.gov (United States)

    Ahn, Kyoungkwan

    In teleoperation field robotic system such as hydraulically actuated robotic excavator, the maneuverability and convenience is the most important in the operation of robotic excavator. Particularly the force information is important in dealing with digging and leveling operation in the teleoperated excavator. This paper presents a new force reflecting joystick in a velocity-force type bilateral teleoperation system. The master system is electrical joystick and the slave system is hydraulic cylinder. Particularly pneumatic motor is used newly in the master joystick for force reflection and the information of the pressure of slave cylinder is measured and utilized as force feedback signal. This paper also proposes a novel force-reflection gain selecting algorithm based on artificial neural network. Finally a series of experiments are conducted under various load conditions using a laboratory-made one axis slave cylinder and load simulator.

  15. In-vivo assessment of femoral bone strength using Finite Element Analysis (FEA based on routine MDCT imaging: a preliminary study on patients with vertebral fractures.

    Directory of Open Access Journals (Sweden)

    Hans Liebl

    Full Text Available To experimentally validate a non-linear finite element analysis (FEA modeling approach assessing in-vitro fracture risk at the proximal femur and to transfer the method to standard in-vivo multi-detector computed tomography (MDCT data of the hip aiming to predict additional hip fracture risk in subjects with and without osteoporosis associated vertebral fractures using bone mineral density (BMD measurements as gold standard.One fresh-frozen human femur specimen was mechanically tested and fractured simulating stance and clinically relevant fall loading configurations to the hip. After experimental in-vitro validation, the FEA simulation protocol was transferred to standard contrast-enhanced in-vivo MDCT images to calculate individual hip fracture risk each for 4 subjects with and without a history of osteoporotic vertebral fractures matched by age and gender. In addition, FEA based risk factor calculations were compared to manual femoral BMD measurements of all subjects.In-vitro simulations showed good correlation with the experimentally measured strains both in stance (R2 = 0.963 and fall configuration (R2 = 0.976. The simulated maximum stress overestimated the experimental failure load (4743 N by 14.7% (5440 N while the simulated maximum strain overestimated by 4.7% (4968 N. The simulated failed elements coincided precisely with the experimentally determined fracture locations. BMD measurements in subjects with a history of osteoporotic vertebral fractures did not differ significantly from subjects without fragility fractures (femoral head: p = 0.989; femoral neck: p = 0.366, but showed higher FEA based risk factors for additional incident hip fractures (p = 0.028.FEA simulations were successfully validated by elastic and destructive in-vitro experiments. In the subsequent in-vivo analyses, MDCT based FEA based risk factor differences for additional hip fractures were not mirrored by according BMD measurements. Our data suggests, that MDCT

  16. Prediction of bone strength by μCT and MDCT-based finite-element-models: How much spatial resolution is needed?

    Energy Technology Data Exchange (ETDEWEB)

    Bauer, Jan S., E-mail: jsb@tum.de [Department of Radiology, Technische Universität München, Munich (Germany); Department of Radiology, University of California, San Francisco, CA (United States); Max Planck Institute for Extraterrestrial Physics, Garching (Germany); Sidorenko, Irina [Max Planck Institute for Extraterrestrial Physics, Garching (Germany); Mueller, Dirk [Department of Radiology, Universität Köln (Germany); Baum, Thomas [Department of Radiology, Technische Universität München, Munich (Germany); Department of Radiology, University of California, San Francisco, CA (United States); Max Planck Institute for Extraterrestrial Physics, Garching (Germany); Issever, Ahi Sema [Department of Radiology, University of California, San Francisco, CA (United States); Department of Radiology, Charite, Berlin (Germany); Eckstein, Felix [Institute of Anatomy and Musculoskeletal Research, Paracelsus Medical University, Salzburg (Austria); Rummeny, Ernst J. [Department of Radiology, Technische Universität München, Munich (Germany); Link, Thomas M. [Department of Radiology, University of California, San Francisco, CA (United States); Raeth, Christoph W. [Max Planck Institute for Extraterrestrial Physics, Garching (Germany)

    2014-01-15

    Objectives: Finite-element-models (FEM) are a promising technology to predict bone strength and fracture risk. Usually, the highest spatial resolution technically available is used, but this requires excessive computation time and memory in numerical simulations of large volumes. Thus, FEM were compared at decreasing resolutions with respect to local strain distribution and prediction of failure load to (1) validate MDCT-based FEM and to (2) optimize spatial resolution to save computation time. Materials and methods: 20 cylindrical trabecular bone specimens (diameter 12 mm, length 15–20 mm) were harvested from elderly formalin-fixed human thoracic spines. All specimens were examined by micro-CT (isotropic resolution 30 μm) and whole-body multi-row-detector computed tomography (MDCT, 250 μm × 250 μm × 500 μm). The resolution of all datasets was lowered in eight steps to ∼2000 μm × 2000 μm × 500 μm and FEM were calculated at all resolutions. Failure load was determined by biomechanical testing. Probability density functions of local micro-strains were compared in all datasets and correlations between FEM-based and biomechanically measured failure loads were determined. Results: The distribution of local micro-strains was similar for micro-CT and MDCT at comparable resolutions and showed a shift toward higher average values with decreasing resolution, corresponding to the increasing apparent trabecular thickness. Small micro-strains (ε{sub eff} < 0.005) could be calculated down to 250 μm × 250 μm × 500 μm. Biomechanically determined failure load showed significant correlations with all FEM, up to r = 0.85 and did not significantly change with lower resolution but decreased with high thresholds, due to loss of trabecular connectivity. Conclusion: When choosing connectivity-preserving thresholds, both micro-CT- and MDCT-based finite-element-models well predicted failure load and still accurately revealed the distribution of local micro-strains in

  17. Remote Excavation System technology evaluation report: Buried Waste Robotics Program

    Energy Technology Data Exchange (ETDEWEB)

    1993-09-01

    This document describes the results from the Remote Excavation System demonstration and testing conducted at the Idaho National Engineering Laboratory during June and July 1993. The purpose of the demonstration was to ascertain the feasibility of the system for skimming soil and removing various types of buried waste in a safe manner and within all regulatory requirements, and to compare the performances of manual and remote operation of a backhoe. The procedures and goals of the demonstration were previously defined in The Remote Excavation System Test Plan, which served as a guideline for evaluating the various components of the system and discussed the procedures used to conduct the tests.

  18. West Heslerton: WEB-CD The application of HTML and WEB Tools for creating a distibuted excavation archive in the form of a WEB-CD

    Directory of Open Access Journals (Sweden)

    Dominic Powlesland

    1998-10-01

    Full Text Available The excavation between 1986 and 1995 of a complete Early and Middle-Saxon settlement at West Heslerton, North Yorkshire, England, by The Landscape Research Centre on behalf of English Heritage (Archaeology Commissions Programme remains one of the largest excavation programmes undertaken in Britain. This excavation, following on from the excavation of an associated cemetery situated only 350m to the north-east of the settlement, forms part of a broader project in landscape archaeology. The Heslerton Parish Project was designed to examine the evolution of the human landscape on the southern margins of the Vale of Pickering from the Mesolithic to the present day. The excavation covered an area in excess of 20ha, examined using open area techniques. The project has been the testing ground for a number of innovative techniques, particularly in the area of applied archaeological computing. These innovations included the use of hand-held computers for field recording (introduced in 1984 and the individual recording of all the finds, the location of each being recorded in 3D using initially an Electronic Distance Meter (EDM and later a Total Station. These approaches to data collection were supported with the addition of digital 3D site plans, often digitised in the field, and the application of high-resolution magnetometry as an aid to excavation. The data set includes: ◦Context Database (27,000 Records ◦Object Database (90,000 Records ◦Animal Bone Database (>800,000 Bone Fragments ◦Environmental Database ◦Digitised Plan incorporating over 15,000 individual drawing objects ◦Drawing Database ◦Photographic Database ◦Stratigraphic Matrices ◦Geophysical and other survey data The examination, analysis and interpretation of this large data set as part of the post-excavation and reporting process combined with the need to distribute as much data as possible to the many contributing specialists pose a number of challenging problems. These are

  19. 1999 Excavation on the Gejiazhuang Site in Xingtai City,Hebei%河北邢台市葛家庄遗址1999年发掘简报

    Institute of Scientific and Technical Information of China (English)

    河北省文物研究所; 吉林大学边疆考古研究中心; 邢台市文物管理处

    2005-01-01

    In the first half of 1999, the Hebei Provincial Institute of Cultural Relics and other institutions carried out a large-scale excavation in the east of the northern area of the Gejiazhuang site in Xingtai City. The work resulted in the revelation of a great number of ash-pits, cellars, sacrificial pits and tombs, as well as quantities of pottery, stone, bone, antler, shell and bronze objects and oracle bones and shells. The remains discovered can be divided into four phases with six stages: The first phase belongs to the late Longshan culture, and the second, third and fourth, to the pre-dynastic, middle and late Shang cultures respectively. The second and fourth fall into two stages either, but the richest in content is the third phase. The excavation has important academic value to studying the origin of the Shang people, the demarcation between the Xia and the Shang, and the chronology of the Shang's history.

  20. In vivo measurement of lead in the bones of smelter workers using the four-element 'clover-leaf' geometry detector system

    Energy Technology Data Exchange (ETDEWEB)

    Behinaein, Sepideh; Chettle, David R; Egden, Lesley M [Department of Medical Physics and Applied Radiation Sciences, McMaster University, Hamilton, Ontario, L8S 4K1 (Canada); Atanackovic, Jovica [AECL, Chalk River Laboratories, Dosimetry Services, K0J 1J0, Ontario (Canada); Fleming, David E B [Department of Physics, Mount Allison University, Sackville, New Brunswick, E4L 1E6 (Canada); Nie, Linda H [School of Health Sciences, Purdue University, West Lafayette, IN 47907 (United States); Richard, Norbert; Stever, Susan, E-mail: behinas@mcmaster.ca [Occupational Health Services, Xstrata Zinc, Brunswick Smelter, Belledune, New Brunswick, E8G 2M1 (Canada)

    2011-02-07

    A total of 497 smelter employees from New Brunswick participated in a bone lead survey conducted by McMaster University in 2008 to examine the efficiency of lead exposure control programmes and a four-element 'clover-leaf' geometry detector system. Nearly 42% of the subjects had participated in both the previous surveys performed in 1994 and 1999. After developing the clover-leaf geometry system in 2006, the reliability of the system based on examining the consistency of four detectors and improving the minimum detection limit (MDL) was tested for the first time in 2008 by measuring lead levels of a large population that was occupationally exposed to lead. The Z test was used to study the distribution of the lead concentration calculated based on K{sub {alpha}} and K{sub {beta}} lead x-rays, where the results were broadly consistent with a normal distribution criterion, with relatively small means and standard deviations of between 1 and 2. The MDL of the clover-leaf geometry system was improved on average for tibia and calcaneus by a factor of 3.1 compared to the 1999 and 1994 surveys in which a conventional system (one detector) was used. Furthermore, by comparing the results of the three mentioned surveys, the 2008 results were found to represent the highest precision.

  1. DISCOVERY AND RESEARCH ON JIAHU BONE FLUTES IN WUYANG, CHINA.

    Energy Technology Data Exchange (ETDEWEB)

    JUZHONG, Z.; HARBOTTLE, G.; XINGHUA, X.; CHANGSUI, W.

    2000-11-01

    The site of Jiahu is located in Jiahu village, Wuyang County, Henan province, on the Western edge of the broad plain of Huanhuaihai. On its north the site borders the Sha River, in the upper reaches of the Huai River; its latitude is 33{degree} 36 minutes North, longitude 113{degree} 40 minutes East, and it is 67.5 meters above sea level. Between 1983 and 1987, the Henan Cultural Relics and Archaeology Institute carried out six campaigns of excavation here, revealing an area of 2400 square meters. Except for the trial excavation in the spring of 1983, Zhang Juzhong has been in charge of all the excavations. In early May 1986, while excavating tomb 78, Zhang Juzhong and Yang Zhenwei first discovered two funerary bone flutes. They soon found other, similar bone flutes in tombs 73, 94 and 121 respectively. Mr. Zhang's attention was instantly focused on these remarkable finds. In the campaign of autumn 1986, one or two more bone flutes were discovered in each of tombs 233,273, 263 and 270. Finally, in the spring of 1987, again one or two bone flutes were found in each of the tombs 282, 363,341,411,344 and 387. Up to the end of excavation in June 1987, altogether 25 bone flutes had been found, of which 17 were complete or almost complete, 6 broken or fragmentary and 2 were half-finished examples. Among the 17 complete bone flutes, there were 14 having seven holes, one five-hole, one six-hole and one eight-hole bone flute. In particular, the bone flute M282:20 was exquisitely made, and complete. Zhang Juzhong, the discoverer of the bone flutes, researcher Pei Mingxiang, the. ex-director of the division, who came to the digging site to see the progress of the work, and their coworkers were all understandably very excited.

  2. Assessment of pile response due to deep excavation in close proximity—A case study based on DTL3 Tampines West Station

    Directory of Open Access Journals (Sweden)

    C.G. Chinnaswamy

    2015-12-01

    Full Text Available Ground movements during deep excavations and tunnelling, especially in urban areas, may potentially have major impact on adjacent buildings, structures and utilities. This impact on buildings and structures needs to be assessed by considering the horizontal and vertical displacements induced by deep excavations to determine the necessary mitigation measures. One major factor affecting the degree of severity the impact due to deep excavation may have on the buildings and structures is the type of foundation systems. While methodology in determining the damage category for the buildings on shallow foundation has been quite well established, the methodology for assessing the impact on the pile foundation is not straightforward due to the geometry and complexity of soil structure interaction. Often simplified two-dimensional (2D or comprehensive three-dimensional (3D finite element analyses would be carried out for the stage excavation to predict the displacement and stresses in the piles. Suitable protective and preventive measures would need to be designed and implemented for the existing buildings/structures if the damage category falls within the unacceptable range. This paper discusses the analysis and methodology to assess the effect on the pile foundation of a high-rise building due to the deep excavation of the Down Town Line Stage 3 (DTL3 Tampines West (TPW Station. The approach to assess the geotechnical capacity of the pile as a result of the deep excavation is presented in this paper. Based on the assessment of pile response, predicted movement, structural and geotechnical capacities of the pile, it was found to be within the acceptable limit and the pile foundation has adequate factor of safety with the deep excavation in close proximity.

  3. Detecting defects in diaphragm walls prior to excavation

    NARCIS (Netherlands)

    Spruit, R.; Hopman, V.; Van Tol, A.F.; Broere, W.

    2011-01-01

    Recent incidents with leaking diaphragm walls during construction of subway lines in Amsterdam and Rotterdam (Netherlands) have led to reconsideration of the diaphragm wall as a retaining wall construction for deep excavations. In our opinion the joints between the panels are the weak spot. During

  4. Experimental Study on Excavation Characteristics of Rockmass by Triaxial Test

    Institute of Scientific and Technical Information of China (English)

    谢红强; 姚勇; 何川; 杨庆

    2004-01-01

    Applying MTS rock stiffness test machine, tests under triaxial condition were carried out for rockmass under loading and unloading. By measuring and analyzing such mechanical properties as stress, strain, elastic modulus, Poisson ratio and elastic wave velocity during the whole test process, the differences of mechanical characteristics under loading and unloading conditions were revealed, to provide some useful references for excavation.

  5. Granular Flow and Dynamics of Lunar Simulants in Excavating Implements

    Science.gov (United States)

    Agui, Juan H.; Wilkinson, R. Allen

    2010-01-01

    The exploration of the lunar surface will rely on properly designed excavation equipment for surface preparations and for collection of lunar regolith in In-Situ Resource Utilization (ISRU) processes. Performance efficiency, i.e minimizing loading forces while maximizing material collection, and mass and volume reductions are major design goals. The NASA Glenn Research Center has embarked on an experimental program to determine the flow characteristics and dynamic forces produced by excavation operations using various excavator bucket designs. A new large scale soil bin facility, 2.27 m x 5.94 m x 0.76 m (nominally 8 ft. x 20 ft. x 27 in.) in size, capable of accommodating moderately large test implements was used for the simulations of lunar operations. The soil bin is filled with GRC-3simulant (a mixture of industrial sands and silt with a particle size distribution and the bulk mechanical (shear) strength representative of an average of lunar regolith from different regions) and uses motorized horizontal rails and a vertical actuator to drive the implement through the lunar simulant soil. A six-axis load cell and encoders provide well resolved measurements of the three dimensional forces and torques and motion of the bucket. In addition, simultaneous video allows for the analysis of the flow behavior and structure formation of the regolith during excavation. The data may be useful in anchoring soil mechanic models and to provide engineering data for design consideration.

  6. A clandestine burial in Costa Rica: prospection and excavation.

    Science.gov (United States)

    Congram, Derek R

    2008-07-01

    This case report describes the search for a clandestine grave in Costa Rica for which the police sought the assistance of an archaeologist. An anonymous informant suggested that the victim had been kidnapped and murdered, placed in a shallow grave in the woods, then covered with lime and cement. A search of the area to detect conventional signs of burial (e.g., slumping, different plant growth) resulted in excavation of unrelated features of past disturbance. Different aspects of the grave including the deposition of cement powder over the body prevented its initial discovery. Improvisation of conventional archaeological excavation methods and use of police familiar with archaeological excavation resulted in the location of the grave and exhumation of the victim without loss of important contextual evidence that supported testimony on the cause of death. The taphonomic effects of high-lying ground water and lime in the tropical burial environment are briefly discussed. Recommendations such as the construction of a temporary sump to lower the ground water level in the grave during excavation are made to assist in similar investigations in the future.

  7. Compromised trabecular microarchitecture and lower finite element estimates of radius and tibia bone strength in adults with turner syndrome: a cross-sectional study using high-resolution-pQCT.

    Science.gov (United States)

    Hansen, Stinus; Brixen, Kim; Gravholt, Claus H

    2012-08-01

    Although bone mass appear ample for bone size in Turner syndrome (TS), epidemiological studies have reported an increased risk of fracture in TS. We used high-resolution peripheral quantitative computed tomography (HR-pQCT) to measure standard morphological parameters of bone geometry and microarchitecture, as well as estimated bone strength by finite element analysis (FEA) to assess bone characteristics beyond bone mineral density (BMD) that possibly contribute to the increased risk of fracture. Thirty-two TS patients (median age 35, range 20-61 years) and 32 healthy control subjects (median age 36, range 19-58 years) matched with the TS participants with respect to age and body-mass index were studied. A full region of interest (ROI) image analysis and a height-matched ROI analysis adjusting for differences in body height between groups were performed. Mean bone cross-sectional area was lower in TS patients in radius (-15%) and tibia (-13%) (both p radius (18%, p radius, -36% in tibia, both p radius, -22% in tibia, both p radius, -12% in tibia, both p radius, 23% in tibia, both p radius, and trabecular number in tibia. FEA estimated failure load was lower in TS patients in both radius (-11%) and tibia (-16%) (both p < 0.01) and remained significantly lower in the height-matched ROI analysis. Conclusively, TS patients had compromised trabecular microarchitecture and lower bone strength at both skeletal sites, which may partly account for the increased risk of fracture observed in these patients.

  8. Study of fossil bones by synchrotron radiation micro-spectroscopic techniques and scanning electron microscopy.

    Science.gov (United States)

    Zougrou, I M; Katsikini, M; Pinakidou, F; Paloura, E C; Papadopoulou, L; Tsoukala, E

    2014-01-01

    Earlymost Villafranchian fossil bones of an artiodactyl and a perissodactyl from the Milia excavation site in Grevena, Greece, were studied in order to evaluate diagenetic effects. Optical microscopy revealed the different bone types (fibro-lamellar and Haversian, respectively) of the two fragments and their good preservation state. The spatial distribution of bone apatite and soil-originating elements was studied using micro-X-ray fluorescence (µ-XRF) mapping and scanning electron microscopy. The approximate value of the Ca/P ratio was 2.2, as determined from scanning electron microscopy measurements. Bacterial boring was detected close to the periosteal region and Fe bearing oxides were found to fill bone cavities, e.g. Haversian canals and osteocyte lacunae. In the perissodactyl bone considerable amounts of Mn were detected close to cracks (the Mn/Fe weight ratio takes values up to 3.5). Goethite and pyrite were detected in both samples by means of metallographic microscopy. The local Ca/P ratio determined with µ-XRF varied significantly in metal-poor spots indicating spatial inhomogeneities in the ionic substitutions. XRF line scans that span the bone cross sections revealed that Fe and Mn contaminate the bones from both the periosteum and medullar cavity and aggregate around local maxima. The formation of goethite, irrespective of the local Fe concentration, was verified by the Fe K-edge X-ray absorption fine structure (XAFS) spectra. Finally, Sr K-edge extended XAFS (EXAFS) revealed that Sr substitutes for Ca in bone apatite without obvious preference to the Ca1 or Ca2 unit-cell site occupation.

  9. Construction of three-dimensional finite element model of maxillary dentition and alveolar bone%上颌牙列及牙槽骨三维有限元模型的建立

    Institute of Scientific and Technical Information of China (English)

    张彤; 霍娜; 张璇; 刘洪臣

    2014-01-01

    Objective:To establish a dynamic three-dimensional finite element model of maxillary teeth with pulp cavity and alveolar bone that possesses the biomechanical properties by using the digital technology of the finite element model of maxillary dentition and alveolar bone obtained from spiral CT raw data.Methods:By establishing a three-dimensional geometric model of the craniofacial complex, the local level columns of maxillary teeth and alveolar bone were selected, and the automatic generation of finite element mesh for the selected body model were analyzed by using ANSYS 10.0 software.Results:A three-dimensional finite element model of complete maxillary dentition and alveolar bone was established. The model was composed of 805086 elements and 150753 nodes.Conclusion:Using spiral CT scanning, the finite element analysis tool (ANSYS10.0) to establish a dynamic three-dimensional finite element model of maxillary teeth with pulp cavity and alveolar bone is an effective and efficient method.%目的:探讨利用螺旋CT原始数据建立上颌牙列及牙槽骨三维有限元模型的数字化方法,建立一个具有生物力学特性的,包含牙髓腔的上颌牙列及牙槽骨的动态三维有限元模型。方法:利用自主建立的颅面复合体三维几何模型,选取上颌牙列和牙槽骨所在的局部层面,利用ANSYS10.0软件对所建体的模型自动划分有限元网格。结果:建立了包括完整牙列的上颌牙槽骨三维有限元模型,由805086个单元和150753个节点组成。模型具有良好的几何相似形及其生物力学特性。结论:应用螺旋CT薄层扫描、自编程序和有限元分析工具ANSYS10.0相结合的方法,建立了包含牙髓腔的上颌牙列及牙槽骨的动态三维有限元模型是一种精确度较高的方法。

  10. New Design Concept for an Excavator Arms by Using Composite Material

    Science.gov (United States)

    Solazzi, L.; Assi, A.; Ceresoli, F.

    2017-09-01

    The purpose of the present paper is to lightweight design an excavator arms, by using a different materials and in particular composite material. Specifically, the research is based on the study of a commercial excavator, by determining its geometry and analyzing the load conditions to which it is exposed. These are determined in relation to either the load diagram of the machine or the possible utilities of the excavator, such as the rotation of the machine. The materials used and implemented in the different analytical and numerical elaborations are classic construction steel S 355 (UNI EN 10025-3), high-resistance steel S 890 (UNI EN 10025-6), aluminum Al 6063 T6 (UNI EN 573-3) and the composite material made by carbon fiber and epoxy resin. The adopted constraints for the design of new arms with different materials, non-conventional for these applications, are numerous. The new solutions must present a safety factor either with respect to the yield tensile strength or to the critical load of buckling greater than or equal to the one determined for the excavator in its original geometrical conformation. Another criterion, which has heavily conditioned the geometry of the arms, was given by the fact that the developed solutions must present a very similar value of the maximum displacement in the different load conditions analyzed. A new geometry for arms made by composite material was developed. It was an elliptical conic section, instead of the classic rectangular section, in order to use the filament winding technological process. As for the adoption of the composite material, we focused on the study and the design of this material as long as the interaction with the extremities (made of aluminum) which are interfaced either with the link between the arms or with the elements of the hydraulic plant which serves for the arms movement. From the results developed, it emerges that the solution developed by adopting composite materials is the one that permits the

  11. The gravitational potential energy regeneration system with closed-circuit of boom of hydraulic excavator

    Science.gov (United States)

    Chen, Mingdong; Zhao, Dingxuan

    2017-01-01

    Considering the disadvantage of higher throttling loss for the open-circuit hydrostatic transmission at present, a novel gravitational potential energy regeneration system (GPERS) of the boom of hydraulic excavator, namely the closed-circuit GPERS, is proposed in this paper. The closed-circuit GPERS is based on a closed-circuit hydrostatic transmission and adopts a hydraulic accumulator as main energy storage element fabricated in novel configuration to recover the entire gravitational potential energy of the boom of hydraulic excavator. The matching parameter and control system design are carried out for the proposed system, and the system is modeled based on its physical attributes. Simulation and experiments are performed to validate the employed mathematical models, and then, the velocity and the pressure performance of system are analyzed. It is observed that the closed-circuit GPERS shows better velocity control of the boom and response characteristics. After that, the average working efficiency of the closed-circuit GPERS of boom is estimated under different load conditions. The results indicate that the proposed system is highly effective and that the average working efficiency in different load conditions varied from 60% to 68.2% for the experiment platform.

  12. Numerical analysis of effect of friction between diaphragm wall and soil on braced excavation

    Institute of Scientific and Technical Information of China (English)

    刁钰; 郑刚

    2008-01-01

    A plane strain finite element model was established to investigate the effect of friction between diaphragm wall and soil on braced excavation. The behavior of interface between diaphragm wall and soil was simulated with the interface model of ABAQUS. Parametric studies were conducted with different diaphragm wall external friction angles δ. The results show that deflection of diaphragm wall and ground surface settlement decrease with the decrease of δ. However, the reduction effect on diaphragm wall deflection is the most significant at the depth where the maximum wall deflection occurs and can be neglected at the wall base. The ratio between wall deep inward component and wall cantilever component reaches its peak value 2.7 when δ=5°. The ratio of the maximum ground surface settlement to the maximum wall lateral deflection decreases at a reduced rate with the increase of δ. For excavation with braced diaphragm wall, the effect of friction between diaphragm and soil on the deflection of diaphragm wall and ground settlement, especially the distribution of ground surface settlement behind diaphragm, should be taken into account.

  13. Ground reaction curves for circular excavations in non-homogeneous, axisymmetric strain-softening rock masses

    Institute of Scientific and Technical Information of China (English)

    J. González-Cao; F. Varas; F.G. Bastante; L.R. Alejano

    2013-01-01

    Fast methods to solve the unloading problem of a cylindrical cavity or tunnel excavated in elasto-perfectly plastic, elasto-brittle or strain-softening materials under a hydrostatic stress field can be derived based on the self-similarity of the solution. As a consequence, they only apply when the rock mass is homoge-neous and so exclude many cases of practical interest. We describe a robust and fast numerical technique that solves the tunnel unloading problem and estimates the ground reaction curve for a cylindrical cavity excavated in a rock mass with properties depending on the radial coordinate, where the solution is no longer self-similar. The solution is based on a continuation-like approach (associated with the unloading and with the incremental formulation of the elasto-plastic behavior), finite element spatial discretization and a combination of explicit sub-stepping schemes and implicit techniques to integrate the constitutive law, so as to tackle the difficulties associated with both strong strain-softening and elasto-brittle behav-iors. The developed algorithm is used for two practical ground reaction curve computation applications. The first application refers to a tunnel surrounded by an aureole of material damaged by blasting and the second to a tunnel surrounded by a ring-like zone of reinforced (rock-bolted) material.

  14. Optimization design of an interior permanent-magnet synchronous machine for a hybrid hydraulic excavator

    Institute of Scientific and Technical Information of China (English)

    Qi-huai CHEN; Qing-feng WANG; Tao WANG

    2015-01-01

    A hybrid power transmission system (HPTS) is a promising way to save energy in a hydraulic excavator and the electric machine is one of the key components of the system. In this paper, a design process for permanent-magnet synchronous machines (PMSMs) in a hybrid hydraulic excavator (HHE) is presented based on the analysis of the working conditions and requirements of an HHE. A parameterized design approach, which combines the analytical model and the 2D finite element method (FEM), is applied to the electric machine to improve the design efficiency and accuracy. The analytical model is employed to optimize the electric machine efficiency and obtain the stator dimension and flux density distribution. The rotor is designed with the FEM to satisfy the flux requirements obtained in stator design. The rotor configuration of the PMSM employs an interior magnet structure, thus resulting in some inverse saliency, which allows for much higher values in magnetic flux density. To reduce the rotor leakage, a disconnected type silicon steel block structure is adopted. To improve the air gap flux density distribution, the trapezoid permanent magnet (PM) and centrifugal rotor structure are applied to PMSM. Demagnetization and armature reactions are also taken into consideration and calculated by the FEM. A prototype of the newly designed electric machine has been fabri-cated and tested on the experimental platform. The analytical design results are validated by measurements.

  15. 18 CFR 1304.207 - Channel excavation on TVA-owned residential access shoreland.

    Science.gov (United States)

    2010-04-01

    ... 18 Conservation of Power and Water Resources 2 2010-04-01 2010-04-01 false Channel excavation on... Resources TENNESSEE VALLEY AUTHORITY APPROVAL OF CONSTRUCTION IN THE TENNESSEE RIVER SYSTEM AND REGULATION... excavation on TVA-owned residential access shoreland. (a) Excavation of individual boat channels shall be...

  16. Does the availability of artificial cavities affect cavity excavation rates in red-cockaded woodpeckers?

    Science.gov (United States)

    Richard N. Conner; Daniel Saenz; D. Craig Rudolph; Richard R. Schaefer

    2002-01-01

    Rates of cavity excavation by Red-cockaded Woodpeckers (Picoides borealis) were examined from 1983 to 1999 on the Angelina National Forest in east Texas. We compared the rare of natural cavity excavation between 1983 and 1990 (before artificial cavities were available) with the rate of cavity excavation between 1992 and 1993, a period when...

  17. Micromechanical finite-element modeling and experimental characterization of the compressive mechanical properties of polycaprolactone-hydroxyapatite composite scaffolds prepared by selective laser sintering for bone tissue engineering.

    Science.gov (United States)

    Eshraghi, Shaun; Das, Suman

    2012-08-01

    Bioresorbable scaffolds with mechanical properties suitable for bone tissue engineering were fabricated from polycaprolactone (PCL) and hydroxyapatite (HA) by selective laser sintering (SLS) and modeled by finite-element analysis (FEA). Both solid gage parts and scaffolds having 1-D, 2-D and 3-D orthogonal, periodic porous architectures were made with 0, 10, 20 and 30 vol.% HA. PCL:HA scaffolds manufactured by SLS had nearly full density (99%) in the designed solid regions and had excellent geometric and dimensional control. Through optimization of the SLS process, the compressive moduli for our solid gage parts and scaffolds are the highest reported in the literature for additive manufacturing. The compressive moduli of solid gage parts were 299.3, 311.2, 415.5 and 498.3 MPa for PCL:HA loading at 100:0, 90:10, 80:20 and 70:30, respectively. The compressive effective stiffness tended to increase as the loading of HA was increased and the designed porosity was lowered. In the case of the most 3-D porous scaffold, the compressive modulus more than doubled from 14.9 to 36.2 MPa when changing the material from 100:0 to 70:30 PCL:HA. A micromechanical FEA model was developed to investigate the reinforcement effect of HA loading on the compressive modulus of the bulk material. Using a first-principles based approach, the random distribution of HA particles in a solidified PCL matrix was modeled for any HA loading to predict the bulk mechanical properties of the composites. The bulk mechanical properties were also used for FEA of the scaffold geometries. The results of the FEA were found to be in good agreement with experimental mechanical testing. The development of patient- and site-specific composite tissue-engineering constructs with tailored properties can be seen as a direct extension of this work on computational design, a priori modeling of mechanical properties and direct digital manufacturing.

  18. Micromechanical finite element modeling and experimental characterization of the compressive mechanical properties of polycaprolactone:hydroxyapatite composite scaffolds prepared by selective laser sintering for bone tissue engineering

    Science.gov (United States)

    Eshraghi, Shaun; Das, Suman

    2012-01-01

    Bioresorbable scaffolds with mechanical properties suitable for bone tissue engineering were fabricated from polycaprolactone (PCL) and hydroxyapatite (HA) by selective laser sintering (SLS) and modeled by finite element analysis (FEA). Both solid gage parts and scaffolds having 1-D, 2-D and 3-D orthogonal, periodic porous architectures were made with 0, 10, 20 and 30% HA by volume. PCL:HA scaffolds manufactured by SLS had nearly full density (99%) in the designed solid regions and had excellent geometric and dimensional control. Through optimization of the SLS process, the compressive moduli for our solid gage parts and scaffolds are the highest reported in the literature for additive manufacturing. The compressive moduli of solid gage parts were 299.3, 311.2, 415.5 and 498.3 MPa for PCL:HA loading at 100:0, 90:10, 80:20 and 70:30 respectively. The compressive effective stiffness tended to increase as the loading of HA was increased and the designed porosity was lowered. In the case of the most 3-D porous scaffold, the compressive modulus more than doubled from 14.9 MPa to 36.2 MPa when changing the material from 100:0 to 70:30 PCL:HA. A micromechanical finite element analysis (FEA) model was developed to investigate the reinforcement effect of HA loading on the compressive modulus of the bulk material. Using a first-principles based approach, the random distribution of HA particles in a solidified PCL matrix was modeled for any loading of HA to predict the bulk mechanical properties of the composites. The bulk mechanical properties were also used for FEA of the scaffold geometries. Results of the FEA were found to be in good agreement with experimental mechanical testing. The development of patient and site-specific composite tissue engineering constructs with tailored properties can be seen as a direct extension of this work on computational design, a priori modeling of mechanical properties and direct digital manufacturing. PMID:22522129

  19. Finite element micro-modelling of a human ankle bone reveals the importance of the trabecular network to mechanical performance: new methods for the generation and comparison of 3D models.

    Science.gov (United States)

    Parr, W C H; Chamoli, U; Jones, A; Walsh, W R; Wroe, S

    2013-01-04

    Most modelling of whole bones does not incorporate trabecular geometry and treats bone as a solid non-porous structure. Some studies have modelled trabecular networks in isolation. One study has modelled the performance of whole human bones incorporating trabeculae, although this required considerable computer resources and purpose-written code. The difference between mechanical behaviour in models that incorporate trabecular geometry and non-porous models has not been explored. The ability to easily model trabecular networks may shed light on the mechanical consequences of bone loss in osteoporosis and remodelling after implant insertion. Here we present a Finite Element Analysis (FEA) of a human ankle bone that includes trabecular network geometry. We compare results from this model with results from non-porous models and introduce protocols achievable on desktop computers using widely available softwares. Our findings show that models including trabecular geometry are considerably stiffer than non-porous whole bone models wherein the non-cortical component has the same mass as the trabecular network, suggesting inclusion of trabecular geometry is desirable. We further present new methods for the construction and analysis of 3D models permitting: (1) construction of multi-property, non-porous models wherein cortical layer thickness can be manipulated; (2) maintenance of the same triangle network for the outer cortical bone surface in both 3D reconstruction and non-porous models allowing exact replication of load and restraint cases; and (3) creation of an internal landmark point grid allowing direct comparison between 3D FE Models (FEMs).

  20. Bone Biopsy

    Science.gov (United States)

    ... News Physician Resources Professions Site Index A-Z Bone Biopsy Bone biopsy uses a needle and imaging ... the limitations of Bone Biopsy? What is a Bone Biopsy? A bone biopsy is an image-guided ...

  1. Osteoporosis and trace elements

    DEFF Research Database (Denmark)

    Aaseth, J.; Boivin, G.; Andersen, Ole

    2012-01-01

    More than 200 million people are affected by osteoporosis worldwide, as estimated by 2 million annual hip fractures and other debilitating bone fractures (vertebrae compression and Colles' fractures). Osteoporosis is a multi-factorial disease with potential contributions from genetic, endocrine...... in new bone and results in a net gain in bone mass, but may be associated with a tissue of poor quality. Aluminum induces impairment of bone formation. Gallium and cadmium suppresses bone turnover. However, exact involvements of the trace elements in osteoporosis have not yet been fully clarified...

  2. The Montana ALE (Autonomous Lunar Excavator) Systems Engineering Report

    Science.gov (United States)

    Hull, Bethanne J.

    2012-01-01

    On May 2 1-26, 20 12, the third annual NASA Lunabotics Mining Competition will be held at the Kennedy Space Center in Florida. This event brings together student teams from universities around the world to compete in an engineering challenge. Each team must design, build and operate a robotic excavator that can collect artificial lunar soil and deposit it at a target location. Montana State University, Bozeman, is one of the institutions selected to field a team this year. This paper will summarize the goals of MSU's lunar excavator project, known as the Autonomous Lunar Explorer (ALE), along with the engineering process that the MSU team is using to fulfill these goals, according to NASA's systems engineering guidelines.

  3. Various Tunnel Excavation Methods used on the LHC Project

    CERN Document Server

    Fielder, R

    2000-01-01

    Civil Engineering construction work for the LHC Project began in April 1998 and is now well underway. A major part of this work is the construction of the new tunnels, caverns and cavern enlargements for the LHC experiments and machine. Currently, this underground work is being carried out for the two injection tunnels, TI2 and TI8, and at Point 1 for the Atlas Experiment. There are three contractors involved in these tunnelling works and each contactor is using a different technique. This paper will outline the different methods used for excavation and the reasons for these differences. It will also examine the other operations involved in the construction of major underground structures such as supply of materials to the tunnel face, evacuation of excavated material and ventilation.

  4. End effectors and attachments for buried waste excavation equipment

    Energy Technology Data Exchange (ETDEWEB)

    King, R.H.

    1993-09-01

    The Buried Waste Integrated Demonstration (BWID) supports the applied research, development, demonstration, and evaluation of a suite of advanced technologies that form a comprehensive remediation system for the effective and efficient remediation of buried waste. Their efforts are identified and coordinated in support of the U.S. Department of Energy (DOE), Environmental Restoration and Waste Management (ER&WM) Department`s needs and objectives. The present focus of BWID is to support retrieval and ex-situ treatment configuration options. Future activities will explore and support containment, and stabilization efforts in addition to the retrieval/ex situ treatment options. This report presents a literature search on the state-of-the-art in end effectors and attachments in support of excavator of buried transuranic waste. Included in the report are excavator platforms and a discussion of the various attachments. Also included is it list of vendors and specifications.

  5. SAFETY HEALTH IMPACTS OF PARTICULATE MATTER FROM EXCAVATION WORK SITES

    Directory of Open Access Journals (Sweden)

    Giuseppe Pizzo

    2012-01-01

    Full Text Available Epidemiological studies have shown a linear relationship between airborne particulates and effects on human health. This study examines the risk that can be run by populations which are exposed to significant pollutant sources such as excavation in urban areas for renovation work. The health risk assessment methodology defined by the WHO air quality guidelines for Europe was applied to assess the possible health effects from exposure to PM10 for daily average concentrations greater than 50 µg m-3 and greater than 100 µg m-3 for three consecutive days and for increments of 10 µg m-3. The methodology adopted was based on daily average concentrations detected in a monitoring period of 8 months in different areas in and around the excavation work site with concentrations of PM10 below or above the legal limits. The exposure estimates calculated show that urban areas with excavation work sites are damaging to human health, due to the large number of people exposed and the already high concentrations of PM10 within cities. It was found that even when in parts of a work site legal limits of PM10 are not exceeded, adverse effects on health still occur. The application, in the present study, of the WHO methodology of exposure assessment indicates the risk ratio for effects on human health. Epidemiological data do not suggest exposition threshold values below which there are no adverse health effects. It is not possible to identify a PM10 concentration value, attributable to an additional source, such as an excavation work site, below which there is no damage. The purpose of this research is therefore to stimulate debate and decisions by public authorities, in order to deepen knowledge and to address issues related to airborne particulates.

  6. The Application of Foundation Pit Monitoring Technology to the Excavation

    OpenAIRE

    Qiu Jin; Li Fei

    2015-01-01

    The foundation pit monitoring plays an important role in the foundation pit supporting projects especially in those deep foundation pit projects. Through the whole monitoring of the foundation pit construction from the excavation to the backfill, we can learn about the forcing and deforming process of the foundation pit supporting system, and grasp the impact of external condition changes on the foundation pit. This paper takes a project in Jinan as an example to establish a specific monitori...

  7. Excavations of the Tinglin Site, Shanghai in 1988 and 1990

    Institute of Scientific and Technical Information of China (English)

    张明华; 李峰; 焦天龙

    2003-01-01

    The Tinglin 亭林 Site is located at the Tinglin Township, Jinshan 金山 District, Shanghai 上海 Municipality. It was discovered in 1966 when a local water supply facility was constructed. In 1988 and 1990, we excavated 968 sq m at this site and found two Song Dynasty tombs, one Tang Dynasty tomb and 23 burials of the Liangzhu 良渚 Culture (Fig. 1). This paper reports the discovery of the burials of the Liangzhu Culture.

  8. Bone Densitometry (Bone Density Scan)

    Science.gov (United States)

    ... News Physician Resources Professions Site Index A-Z Bone Densitometry (DEXA) Bone densitometry, also called dual-energy ... limitations of DEXA Bone Densitometry? What is a Bone Density Scan (DEXA)? Bone density scanning, also called ...

  9. ROCK MASS DAMAGED ZONE CAUSED BY BLASTING DURING TUNNEL EXCAVATION

    Directory of Open Access Journals (Sweden)

    Hrvoje Antičević

    2012-07-01

    Full Text Available Design of underground spaces, including tunnels, and repositories for radioactive waste include the application of the same or similar technologies. Tunnel excavation by blasting inevitably results in the damage in the rock mass around the excavation profile. The damage in the rock mass immediately next to the tunnel profile emerges as the expanding of the existing cracks and the appearance of new cracks, i.e. as the change of the physical and-mechanical properties of the rock mass. Concerning the design of deep geological repositories, requirements in terms of damaged rock are the same or more rigorous than for the design of tunnel. The aforementioned research is directed towards determining the depth of damage zone caused by blasting. The depth of the damage zone is determined by measuring the changes of physical and-mechanical properties of the rock mass around the tunnel excavation profile. By this research the drilling and blasting parameters were correlated with the depth and size of the damage zone (the paper is published in Croatian.

  10. Soil Lysimeter Excavation for Coupled Hydrological, Geochemical, and Microbiological Investigations.

    Science.gov (United States)

    Sengupta, Aditi; Wang, Yadi; Meira Neto, Antonio A; Matos, Katarena A; Dontsova, Katerina; Root, Rob; Neilson, Julie W; Maier, Raina M; Chorover, Jon; Troch, Peter A

    2016-09-11

    Studying co-evolution of hydrological and biogeochemical processes in the subsurface of natural landscapes can enhance the understanding of coupled Earth-system processes. Such knowledge is imperative in improving predictions of hydro-biogeochemical cycles, especially under climate change scenarios. We present an experimental method, designed to capture sub-surface heterogeneity of an initially homogeneous soil system. This method is based on destructive sampling of a soil lysimeter designed to simulate a small-scale hillslope. A weighing lysimeter of one cubic meter capacity was divided into sections (voxels) and was excavated layer-by-layer, with sub samples being collected from each voxel. The excavation procedure was aimed at detecting the incipient heterogeneity of the system by focusing on the spatial assessment of hydrological, geochemical, and microbiological properties of the soil. Representative results of a few physicochemical variables tested show the development of heterogeneity. Additional work to test interactions between hydrological, geochemical, and microbiological signatures is planned to interpret the observed patterns. Our study also demonstrates the possibility of carrying out similar excavations in order to observe and quantify different aspects of soil-development under varying environmental conditions and scale.

  11. 颌面骨三维有限元模型中骨缝实体模型的建立%Sutural physical model building in the three-dimensional finite-element model of maxillofacial bones

    Institute of Scientific and Technical Information of China (English)

    刘畅; 朱宪春; 张星; 台银霞; 闫森

    2011-01-01

    Objective To build the physical model of four suturae which are related to the growth of maxilla in the three-dimensional finite-element model of maxillofacial bones. Methods A 16 years old volunteer with individual normal occlusion, good periodontium health condition and without diseases of temporomandibular joint was chosen to be the material of modeling. The three-dimensional finite-element model of the volunteer's maxillofacial bones was built using the CT scan and the finite-element modeling method. Finally we built the physical model of four suturae which were related to the growth of maxilla in the model of maxillofacial bones. Results The model of maxillofacial bones with 86 575 nodes and 485 915 elements was generated. This model contained four suturae including sutura frontomaxillaris, sutura zygomaticomaxillaris, sutura temporozygomafica and sutura pterygopalatine. Conclusion A three-dimensional finite-element model of maxillofacial bones with good biological similarity was developed.%目的 在颌面骨三维有限元模型中建立与上颌骨生长密切相关的4条骨缝实体模型.方法以1名个别正常(牙合)、牙周组织健康、无颞下颌关节疾病的16岁女性为建模素材,应用螺旋CT扫描与有限元法相结合的方法,建立颌面骨的三维有限元模型,并在此基础上建立额颌缝、颧颌缝、颞颧缝、翼腭缝4条与上颌骨生长有关的骨缝实体模型.结果 生成了具有86575个节点、485915个单元的颌面骨三维有限元模型,其中包括额颌缝、颧颌缝、颞颧缝、翼腭缝4条实体骨缝.结论 获得了生物相似性良好的颌面骨三维有限元模型.

  12. Optimal design of the front linkage of a hydraulic excavator for multi-objective function

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jong Won; Jung, Seung Min; Kim, Jong Won [Seoul National University, Seoul (Korea, Republic of); Kim, Jin Uk [Doosan Infracore, Incheon (Korea, Republic of); Seo, Tae Won [Yeungnam University, Gyeongsan (Korea, Republic of)

    2014-08-15

    The workspace, working velocity, excavating force, and load capacity of a hydraulic excavator play critical roles in the performance of the excavator for various tasks. This paper presents an optimal design of the front linkage of an excavator to maximize the performances of several indices simultaneously. A multi-objective function is defined to increase the excavator's workspace, working velocity, excavating force, and load capacity simultaneously. The workspace is defined by using four geometrical indices and the working velocity is defined by the amount of time needed to perform one cycle composed of digging and dumping. The excavating force consists of two forces, and the load capacity is defined by using the minimum values of three types with specific operations. A total of 10 indices define objective function with each weight, and pin-points of the front linkage are the design parameters, including joint positions of links and hydraulic actuators. A two-step optimization procedure is considered based on a new method called the hybrid Taguchi-random coordinate search algorithm. The results indicate a 3.43% increase in performance relative to the initial design parameters of a commercial excavator. More specifically, the excavator's workspace, working velocity, excavating force, and load capacity increase by 5.55%, 0.14%, 5.46%, and 0.33%, respectively. These improved design parameters can be applied to next generation excavators.

  13. Excavation of Bohai Period House-foundations on the Xiaodiying Site in Dongning County, Heilongjiang%黑龙江东宁县小地营遗址渤海房址

    Institute of Scientific and Technical Information of China (English)

    黑龙江省文物考古研究所

    2003-01-01

    In September through October 1990, the Heilongjiang Provincial Institute of Cultural Relics and Archaeology along with other institutions excavated three house-foundations of the Bohai period at Xiaodiying in Dongning County. These vestiges are the remains of semi-subterranean houses, each having a fireplace at the center and measuring 42~53 sq m. They belonged to common people of the early and middle Bohai period. The unearthed objects include pottery, iron, bone and horn wares, all coming from the deposits within the houses. The excavation of the site enriched the further study of the Bohai culture in eastern Heilongjiang Province.

  14. A Review on Mechanical and Hydraulic System Modeling of Excavator Manipulator System

    Directory of Open Access Journals (Sweden)

    Jiaqi Xu

    2016-01-01

    Full Text Available A recent trend in the development of off-highway construction equipment, such as excavators, is to use a system model for model-based system design in a virtual environment. Also, control system design for advanced excavation systems, such as automatic excavators and hybrid excavators, requires system models in order to design and simulate the control systems. Therefore, modeling of an excavator is an important first step toward the development of advanced excavators. This paper reviews results of recent studies on the modeling of mechanical and hydraulic subsystems for the simulation, design, and control development of excavator systems. Kinematic and dynamic modeling efforts are reviewed first. Then, various approaches in the hydraulic system modeling are presented.

  15. Heybridge: A late Iron Age and Roman settlement. Excavations at Elms Farm 1993-5. Volume 2

    Directory of Open Access Journals (Sweden)

    Mark Atkinson

    2015-12-01

    Full Text Available The Late Iron Age, Roman and early Saxon settlement at Elms Farm, Heybridge, Essex was excavated in the mid-1990s, in advance of the construction of a large housing estate by Bovis Homes Ltd. The total development area comprised c. 29 hectares, of which some 18ha were subject to varying degrees of investigation by the Essex County Council Field Archaeology Unit (ECC FAU. The large-scale of the excavations is matched by the substantial and important artefact assemblage recovered, which included 6.4 tonnes of Late Iron Age and Roman pottery, 2,910 Roman coins and over 9000 animal bones. Together this has enabled an appreciation of the development of the settlement over time and space, of the changing functions, status and economy of individual areas and the settlement as a whole, and the issues of transition, change and finally decline. The site revealed evidence for activity from the Bronze Age to the post-medieval period. The evidence for the earliest settlement dates to the Late Iron Age period (mid 1st century BC and is rather fragmentary in nature. However a centrally located shrine, with a series of strip-plots to the north and south were tentatively identified. This settlement was remodelled around the mid 1st century AD, with the creation of a formal infrastructure of metalled roads, as well as a new temple precinct on the earlier sacred site and a reworking of the strip-plots into enclosures. This remodelling spanned the Late Iron Age/early Roman transition period, although the new road network is tentatively dated to the decade or two preceding the Roman conquest. To the north of the settlement area were a number of burials, pyre sites and pyre debris dumps. Early Roman cremations were added to this area slightly later. Some of the pyre sites exhibit higher-status elements, and at least one may have been 'aristocratic', suggesting the presence of a local elite. Reconstruction of settlement at Heybridge by Roger Massey-Ryan The later 1st

  16. Dynamical modelling of the excavating chain of a ballast cleaning machine

    Directory of Open Access Journals (Sweden)

    Boris Petkov

    2015-12-01

    Full Text Available The ballast bed as part of the railway track fulfils the important functions as the binding element between sleepers and substructure. Fouling increases over the years for various reasons. When the necessary good functioning is no longer assured, ballast bed cleaning must be performed. The machines, that perform that task, are equipped with various complex mechanics - hydraulic systems that ensure high productivity, efficiency and quality of the works. In this article is presented one way of studying the work of the machine for excavating ballast from the ballast bed to the sieving machine. We suggest a dynamic model for simulating the work of a scraper chain of a ballast cleaning machine with different working parameters.

  17. Seismic Waves Scattering Impact through Tunnel Excavation on Adjacent Monuments Subjected to Far Field Earthquakes

    Directory of Open Access Journals (Sweden)

    Ghobakhloo E.

    2015-09-01

    Full Text Available The study of the effect of seismic wave scattering has attracted extensive attention in the past couple of decades especially in infrastructures like tunnels. A seismic wave, meeting the tunnel, can generate scattering which, in most cases, may incur damages in adjacent structures. In this study, using Finite Element Method (FEM, the effect of seismic wave scattering in far field has been investigated. The twin tunnels of Shiraz subway system are selected as the case study in this research and three far field seismic waves were chosen for time history analyses. Investigating the normal mode (before tunnel construction in comparison to the excavation mode (after tunnel construction enables calculation of the effect of displacement in adjacent structures. The analysis results indicate there is a significant difference between before and after tunnel construction (P-value<0.05. Accordingly, the influence of constructing a tunnel on adjacent surface structures is very important for tunnel design.

  18. Sloped implants applied to different types of jaw bone:A three-dimensional finite element analysis%倾斜种植应用于不同质量颌骨的三维有限元分析

    Institute of Scientific and Technical Information of China (English)

    夏琳; 张志宏; 刘红红; 杜双松; 冯昌乐; 韩倩; 陈佳

    2015-01-01

    24 different inclined angle implant models in different types of bone were established by using three-di-mensional finite element method, vertical loading 300N. The final analysis result was: with increase of implant tilt-ing angle in the same types of bone, the maximum stress and strain of both compact bone and cancellous bone rised gradully. However, when the same angle implant applied to different type of jaw, development trend of maximum stress and strain were:compact bone:Type Ⅳ > Type Ⅲ > Type Ⅱ > Type Ⅰ;cancellous bone:Type Ⅲ > Type Ⅳ> Type Ⅱ.%通过运用三维有限元方法建立Ⅰ~Ⅳ类骨质中种植体不同角度倾斜种植模型24个,垂直集中加载300 N。分析研究显示,在同一骨质中,随着种植体倾斜角度的增加,密质骨和松质骨中的最大应力及应变量均逐渐增大;而相同角度的种植体于不同质量的颌骨中时,最大应力发展趋势为:密质骨:Ⅳ类骨质>Ⅲ类骨质>Ⅱ类骨质>Ⅰ类骨质;松质骨:Ⅲ类骨质>Ⅳ类骨质>Ⅱ类骨质。

  19. Pre-excavation studies of prehistoric cave sites by magnetic prospecting

    Science.gov (United States)

    Itkis., Sonia; Matskevich, Zinovii; Meshveliani, Tengiz

    2014-05-01

    stratified Eneolithic deposits (ca. fifth millennium BC), rich in pottery and other material culture remains. Charcoal and animal bones are in good state of preservation that increases the importance of the site. In addition, a built stone wall crossing the excavation area in west-east direction was found in association with an Eneolithic living surface. Magnetic study covers practically whole area of the chamber (about 60 sq. m.) was made adjacent to the excavated area. Soil κ values change in the wide interval of 20 to 140 units SI x 10-5.Nevetheless, the highest κ values 100 to 140 units SI are concentrated in limited area adjacent to the large high intensity (up to 50 nT) positive magnetic anomaly. The latter is limited by two narrow linear negative anomalies of NW-SE and SW-NE orientations which probably indicate location of limestone walls . Excavations in the Kotias-Klde site were conducted in 2004-2006 under direction of O. Bar-Yosef, A. Belfer-Cohen and T. Meshveliani, with participation of the present author. A sequence including Upper Paleolithic, Mesolithic, Neolithic and Eneolithic layers was revealed. Magnetic investigations were performed both in the cave and outside. We will discuss the results obtained in the cave which was tested by excavation.. The survey revealed a large positive magnetic anomaly of square configuration approximately 2.5 by 2.5 meters. There is a dense correlation between T and κ anomalies. The pattern of the T anomaly, its configuration and intensity allows one to suppose that its source is so-called "firing feature", probably, hearth or fireplace. According to preliminary evaluation, the source is buried at the depth of 0.5-0.7 m. Following the magnetic survey, a test trench of 3 sq. m. was opened in the location of positive anomaly. The trench reached depth of 80 cm below the present surface. The stratigraphic sequence exposed in the trench includes two main strata, dated on the basis of typological properties of the associated

  20. Monitoring, Back analysis and Redesign of a Deep excavation Retaining system in marl formation. Case history, Modelling and Interpretation

    Directory of Open Access Journals (Sweden)

    Saydi Chantal

    2014-04-01

    Full Text Available We present in this paper a case study of retaining system of a deep excavation in a marly material in Beirut. The retaining system was redesigned using a new set of mechanical parameter considered more realistic than the set issued from the site investigation study. The new values were issued from back analysis of displacements measurement performed in the same site. The horizontally deflection of the retaining system was measured using three vertical inclinometers. The experimentation results are simulated by numerical calculation using finite elements code.

  1. Logs of Paleoseismic Excavations Across the Central Range Fault, Trinidad

    Science.gov (United States)

    Crosby, Christopher J.; Prentice, Carol S.; Weber, John; Ragona, Daniel

    2009-01-01

    This publication makes available maps and trench logs associated with studies of the Central Range Fault, part of the South American-Caribbean plate boundary in Trinidad. Our studies were conducted in 2001 and 2002. We mapped geomorphic features indicative of active faulting along the right-lateral, Central Range Fault, part of the South American-Caribbean plate boundary in Trinidad. We excavated trenches at two sites, the Samlalsingh and Tabaquite sites. At the Samlalsingh site, sediments deposited after the most recent fault movement bury the fault, and the exact location of the fault was unknown until we exposed it in our excavations. At this site, we excavated a total of eleven trenches, six of which exposed the fault. The trenches exposed fluvial sediments deposited over a strath terrace developed on Miocene bedrock units. We cleaned the walls of the excavations, gridded the walls with either 1 m X 1 m or 1 m X 0.5 m nail and string grid, and logged the walls in detail at a scale of 1:20. Additionally, we described the different sedimentary units in the field, incorporating these descriptions into our trench logs. We mapped the locations of the trenches using a tape and compass. Our field logs were scanned, and unit contacts were traced in Adobe Illustrator. The final drafted logs of all the trenches are presented here, along with photographs showing important relations among faults and Holocene sedimentary deposits. Logs of south walls were reversed in Illustrator, so that all logs are drafted with the view direction to the north. We collected samples of various materials exposed in the trench walls, including charcoal samples for radiocarbon dating from both faulted and unfaulted deposits. The locations of all samples collected are shown on the logs. The ages of seventeen of the charcoal samples submitted for radiocarbon analysis at the University of Arizona Accelerator Mass Spectrometry Laboratory in Tucson, Ariz., are given in Table 1. Samples found in

  2. Coins from excavations in Sexaginta Prista (March-May 2015

    Directory of Open Access Journals (Sweden)

    Nikola Rusev

    2015-12-01

    Full Text Available The late roman fortress Sexaginta Prista is situated on the right bank of Danube River beneath the level of the modern city of Ruse. In 2015 for about three months (the period March-May on that territory over an area of 170 sq. m. were conducted rescue archaeological excavations. As a result part of the eastern wall, one U-shaped tower, the north side of the fortress gate, edifice adjoined to the wall and 40 pits were unearthed. During the research 226 coins from the 5th BC to 20th century were found whose analysis is the topic of this article.

  3. Bone within a bone

    Energy Technology Data Exchange (ETDEWEB)

    Williams, H.J.; Davies, A.M. E-mail: wendy.turner@roh.nhs.uk; Chapman, S

    2004-02-01

    The 'bone within a bone' appearance is a well-recognized radiological term with a variety of causes. It is important to recognize this appearance and also to be aware of the differential diagnosis. A number of common conditions infrequently cause this appearance. Other causes are rare and some remain primarily of historical interest, as they are no longer encountered in clinical practice. In this review we illustrate some of the conditions that can give the bone within a bone appearance and discuss the physiological and pathological aetiology of each where known.

  4. Experience with the RK 5000 bucket chain excavator. Iskustva iz pogona stroja RK 5000

    Energy Technology Data Exchange (ETDEWEB)

    Madry, F.

    1988-01-01

    Highlights technical features of the RK 5000 bucket chain excavator manufactured by the Czechoslovak Vitkovice concern on the basis of the RK-400 excavator. Capacity of the RK-5000 excavator ranges from 3600-4500 m/sup 3//h depending on chain velocity and on the properties of excavated material. Capacity of 5,000 m/sup 3//h was also achieved by overloading the buckets by 12%. The pulling force of the bucket chain is 220 t (excess force of up to 330 t was also achieved for short periods). The working heights (or working depth) may reach 2 m. Bucket volume is 3,650 l. The installed power of the RK-5000 excavator is 2x1,600 kW. Experience gained during trial operation of the RK-5000 excavator in loose soil, and subsequent technical improvements made are presented.

  5. DNA and RNA profiling of excavated human remains with varying postmortem intervals.

    Science.gov (United States)

    van den Berge, M; Wiskerke, D; Gerretsen, R R R; Tabak, J; Sijen, T

    2016-11-01

    When postmortem intervals (PMIs) increase such as with longer burial times, human remains suffer increasingly from the taphonomic effects of decomposition processes such as autolysis and putrefaction. In this study, various DNA analysis techniques and a messenger RNA (mRNA) profiling method were applied to examine for trends in nucleic acid degradation and the postmortem interval. The DNA analysis techniques include highly sensitive DNA quantitation (with and without degradation index), standard and low template STR profiling, insertion and null alleles (INNUL) of retrotransposable elements typing and mitochondrial DNA profiling. The used mRNA profiling system targets genes with tissue specific expression for seven human organs as reported by Lindenbergh et al. (Int J Legal Med 127:891-900, 27) and has been applied to forensic evidentiary traces but not to excavated tissues. The techniques were applied to a total of 81 brain, lung, liver, skeletal muscle, heart, kidney and skin samples obtained from 19 excavated graves with burial times ranging from 4 to 42 years. Results show that brain and heart are the organs in which both DNA and RNA remain remarkably stable, notwithstanding long PMIs. The other organ tissues either show poor overall profiling results or vary for DNA and RNA profiling success, with sometimes DNA and other times RNA profiling being more successful. No straightforward relations were observed between nucleic acid profiling results and the PMI. This study shows that not only DNA but also RNA molecules can be remarkably stable and used for profiling of long-buried human remains, which corroborate forensic applications. The insight that the brain and heart tissues tend to provide the best profiling results may change sampling policies in identification cases of degrading cadavers.

  6. Archaeological Studies of the Ancient Turkestan Site: results of 2011-2012 excavations

    Directory of Open Access Journals (Sweden)

    Smagulov Yerbulat A.

    2013-03-01

    Full Text Available The results of the 2011-12 excavations on the Eski-Turkestan site conducted by the Turkestani archaeological expedition (Institute of archaeology named after A. Margulan are presented. The site contains the remains of the ancient town of Yasy (modern town of Turkestan, South Kazakhstan oblast. The aim of the excavations was to study the earliest layers of the settlement, the primary stages of the city formation, and to identify construction elements of the ancient citadel in particular. It has been established that the most ancient nucleus of the city was located under Kultobe hill on the eastern edge of the settlement. The oldest architectural object of the citadel is a cruciform construction with powerful rammed clay defensive walls having narrow loopholes, preserved to a height of over 3 m. The three rooms were connected by arched doorways. In the second construction horizon, a building with long narrow rooms around a small open courtyard had been added to this "castle". During this period, around the perimeter of the citadel powerful rammed clay and mud-brick defensive walls had been erected, with the space between them and the extended castle being just partially built up. These two periods can be dated to the 1st–3rd centuries AD. This stage comes to an end with defeat and a fire. In the fire layer, numerous ceramic vessels in disassembling have been found. Individual unique finds have been made, and alabaster idols are of special interest. The restoration of the fortification wall and a new stage of the citadel development refer to the 9th-11th centuries. At the base of the new wall, pots with sacrificial food have been discovered, one of them bearing a runic inscription.

  7. Characterization of the disturbed zone in a large rock excavation for the Three Gorges Project

    Energy Technology Data Exchange (ETDEWEB)

    Deng, J.H.; Ge, X.R. [Chinese Academy of Sciences, Wuhan (China); Lee, C.F. [Hong Kong Univ., (China)

    2001-02-01

    In situ studies were conducted in the navigation structures of China's Three Gorges Project. The navigation structures included the permanent shiplock, the shiplift and the temporary shiplock located on the left bank of the Yangtze River. Each of the structures was constructed by deep excavation into the plagioclase granite basement rock to maximum depths of 173.5, 140 and 86 m respectively. A comprehensive study was conducted to determine the mechanical properties and the actual extent of the weakened or disturbed zones. It was determined that excavation in a rock mass results in the disturbance of the stress regime, and creates a stress-relieved, locally weakened zone. The two types of geological and geophysical tests used to determine the vertical extent of this disturbed or weakened zone were the cross-hole seismic wave penetration test and the borehole elastic modulus test. The deformation characteristics were monitored and evaluated to determine the horizontal extent of the weakened zone. It was shown that the P-wave velocity in the disturbed zone was reduced by 34-38 per cent compared to an undisturbed rock. Similarly, the P-wave in the borehole elastic modulus was reduced by 12-31 per cent. This reduction resulted from local sliding along the structural planes which created an opening in the primary structural planes. No newly formed fracture planes were found in the weakened zones. The disturbed zone was compared with both the tensile stress zones and the shear-damaged zones calculated by the finite element method. A reinforcement plan using cable bolts or conventional rock bolts anchored into the undisturbed basement rock was recommended. 4 refs., 5 tabs., 17 figs.

  8. Improved Concrete Cutting and Excavation Capabilities for Crater Repair Phase 2

    Science.gov (United States)

    2015-05-01

    ER D C/ G SL T R- 14 -8 Improved Concrete Cutting and Excavation Capabilities for Crater Repair Phase 2 G eo te ch ni ca l a nd S tr...Improved Concrete Cutting and Excavation Capabilities for Crater Repair Phase 2 Lulu Edwards, Haley P. Bell, Jay F. Rowland Geotechnical and...Engineer Center to further improve the saw cutting and excavation production rates and robustness of crater repairs in thick portland cement concrete

  9. Impact cratering mechanics - Relationship between the shock wave and excavation flow

    Science.gov (United States)

    Melosh, H. J.

    1985-05-01

    This paper describes the relationship between the shock wave produced by an impact and the excavation flow that opens the crater. The excavation flow velocity is shown to be a nearly constant fraction of the peak particle velocity in the wave. The existence of an excavation flow is due to thermodynamically irreversible processes in the shock. The excavation flow velocity is thus very sensitive to nonideal constitutive effects such as porosity, plastic yielding, and unreversed phase transformations. Cratering computations that do not model these effects correctly may produce misleading results.

  10. Parametric Optimization and Prediction Tool for Excavation and Prospecting Tasks Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Honeybee Robotics therefore proposed to develop a software tool for facilitating prospecting and excavation system trades in support of selecting an optimal...

  11. Kinematic control model for light weighting mechanism of excavator attached to rotary working device

    Science.gov (United States)

    Lee, Choongho; Lee, Sangsik; Cho, Youngtae; Im, Kwanghee

    2007-07-01

    An excavator attached to a rotary working device is used principally in industrial work. In particular, they are used in the building industry and public works. This research concerns the rotary automatic control of an excavator attached to a rotary working device. The drilling excavator is used in the crushed stone industry and the dragline excavation system is employed in the construction industry. Cases of the excavator's use in agriculture have been the subject of a relatively few studies. However, several modified excavator designs have been released in recent years. Applied excavator products are primarily utilized under relatively severe environmental conditions. In this study, we focus on the uses of an excavator in agricultural work. The readjustment of arable land and the reduction of weeds in agricultural applications both require skilled hand-operation of the machines. As such workers have been shown to develop problems with regard to working posture and proper positioning while laboring, a more appropriate excavator design may prove useful in such applications. Therefore, this pilot study is focused primarily on the rotary automatic control of an excavator attached to a rotary working device, and will adapt smart materials to the excavator applications for developing redesigned excavator having a light weight. The excavator is attached to a rotary working device on a normal excavator's platform, and the position and orientation of the mechanism between the joints and the rotary working device was determined. Simulations were also conducted of the excavator attached to the rotary working device. With an eye toward the use of this mechanism in agricultural work, we also conducted a set of kinematic analyses. The rotary working device was assumed to have 3 DOF, and was comprised of 5 links. Computer simulations were also conducted using the developed excavator model. In order to adequately evaluate the possible performance of such a system, kinetic

  12. Fluorescence of primary dentine after chemomechanical and conventional rotary excavation.

    Science.gov (United States)

    Corrêa, F N P; Rocha, R O; Soares, F Z M; Rodrigues-Filho, L E; Rodrigues, C R M

    2008-09-01

    This was to compare fluorescence values of dentine remaining after caries removal using chemomechanical systems and conventional rotary methods. In vitro study. 30 extracted primary teeth with proximal carious cavities were divided into three groups according to caries removal method: Carisolv, Papacarie and conventional low speed rotary burs. Carious (initial) and remaining (final) dentine evaluations were assessed by visual-tactile examination and DIAGNOdent. Transversal microhardness (TMH) of remaining dentine was evaluated. Fluorescence and TMH values were submitted to two-way ANOVA and the post hoc Tukey test (alpha = 0.05) and Pearson's linear correlation. Two-way ANOVA revealed that fluorescence values were similar between conventional rotary excavation, Carisolv and Papacarie groups (p = 0.0542). No statistically significant differences (p = 0.1147) were found to TMH values. No correlation was found between fluorescence and TMH values (r = -0.0273). All caries excavation methods resulted in similar remaining dentine fluorescence values. No correlation was found between fluorescence values and TMH of remaining dentine.

  13. From Excavations to Web: a GIS for Archaeology

    Science.gov (United States)

    D'Urso, M. G.; Corsi, E.; Nemeti, S.; Germani, M.

    2017-05-01

    The study and the protection of Cultural Heritage in recent years have undergone a revolution about the search tools and the reference disciplines. The technological approach to the problem of the collection, organization and publication of archaeological data using GIS software has completely changed the essence of the traditional methods of investigation, paving the way to the development of several application areas, up to the Cultural Resource Management. A relatively recent specific sector of development for archaeological GIS development sector is dedicated to the intra - site analyses aimed to recording, processing and display information obtained during the excavations. The case - study of the archaeological site located in the south - east of San Pietro Vetere plateau in Aquino, in the Southern Lazio, is concerned with the illustration of a procedure describing the complete digital workflow relative to an intra-site analysis of an archaeological dig. The GIS project implementation and its publication on the web, thanks to several softwares, particularly the FOSS (Free Open Source Software) Quantum - GIS, are an opportunity to reflect on the strengths and the critical nature of this particular application of the GIS technology. For future developments in research it is of fundamental importance the identification of a digital protocol for processing of excavations (from the acquisition, cataloguing, up data insertion), also on account of a possible future Open Project on medieval Aquino.

  14. Target and Projectile: Material Effects on Crater Excavation and Growth

    Science.gov (United States)

    Anderson, J. L. B.; Burleson, T.; Cintala, Mark J.

    2010-01-01

    Scaling relationships allow the initial conditions of an impact to be related to the excavation flow and final crater size and have proven useful in understanding the various processes that lead to the formation of a planetary-scale crater. In addition, they can be examined and tested through laboratory experiments in which the initial conditions of the impact are known and ejecta kinematics and final crater morphometry are measured directly. Current scaling relationships are based on a point-source assumption and treat the target material as a continuous medium; however, in planetary-scale impacts, this may not always be the case. Fragments buried in a megaregolith, for instance, could easily approach or exceed the dimensions of the impactor; rubble-pile asteroids could present similar, if not greater, structural complexity. Experiments allow exploration into the effects of target material properties and projectile deformation style on crater excavation and dimensions. This contribution examines two of these properties: (1) the deformation style of the projectile, ductile (aluminum) or brittle (soda-lime glass) and (2) the grain size of the target material, 0.5-1 mm vs. 1-3 mm sand.

  15. Trabecular bone strains around a dental implant and associated micromotions--a micro-CT-based three-dimensional finite element study.

    NARCIS (Netherlands)

    Limbert, G.; Lierde, C. van; Muraru, O.L.; Walboomers, X.F.; Frank, M.; Hansson, S.; Middleton, J.; Jaecques, S.

    2010-01-01

    The first objective of this computational study was to assess the strain magnitude and distribution within the three-dimensional (3D) trabecular bone structure around an osseointegrated dental implant loaded axially. The second objective was to investigate the relative micromotions between the impla

  16. 黑龙江友谊县凤林古城址的发掘%Excavation on the Ancient Fenglin City-site in Youyi County, Heilongjiang

    Institute of Scientific and Technical Information of China (English)

    黑龙江省文物管理委员会

    2004-01-01

    In 2001, the Heilongjiang Provincial Commission for the Preservation of Ancient Monuments carried out survey and excavation on the Fenglin city-site. The unearthed remains can be divided into two phases. The early remains include house-foundations, as well as pottery jars, single-handle jars and balls and jade cicadas. The late vestiges are house-foundations, ash-pits and city-wall ruins. Among the objects from Phase Ⅱ, the pottery consists of jars, bowls, dou stemmed vessels, zeng steamers, cups, spindle whorls, net weights and sculptures. The stone implements embrace axes,knives, grindstones, querns and tubes; the bone artifacts belong to the types of arrowhead, hairpin, belt buckle, chisel-shaped object, oracle bone, etc. The bronzes fall into gilt buttons, ornamental tubes, finger rings, loops and belt buckles; and the ironware, into knives, needles, arrowheads, awls, fishhooks and plates of armor. In addition, there are a number of animal bones, which belong to the wild boar, ox,deer, cat, antelope, roe deer, musk deer, dog and fish. The excavation results reveal the distinctive structural forms of the city and its walls and houses, and suggest that the site represents a new cultural type.

  17. Spectroscopic and statistical approach of archaeological artifacts recently excavated from Tamilnadu, South India

    Science.gov (United States)

    Seetha, D.; Velraj, G.

    2015-10-01

    The ancient materials characterization will bring back the more evidence of the ancient people life styles. In this study, the archaeological pottery shards recently excavated from Kodumanal, Erode District in Tamilnadu, South India were investigated. The experimental results enlighten us to the elemental and the mineral composition of the pottery shards. The FT-IR technique tells that the mineralogy and the firing temperature of the samples are less than 800 °C, in the oxidizing/reducing atmosphere and the XRD was used as a complementary technique for the mineralogy. A thorough scientific study of SEM-EDS with the help of statistical approach done to find the provenance of the selected pot shards has not yet been performed. EDS and XRF results revealed that the investigated samples have the elements O, Si, Al, Fe, Mn, Mg, Ca, Ti, K and Na are in different compositions. For establishing the provenance (same or different origin) of pottery samples, Al and Si concentration ratio as well as hierarchical cluster analysis (HCA) was used and the results are correlated.

  18. High-resolution peripheral quantitative computed tomography and finite element analysis of bone strength at the distal radius in ovariectomized adult rhesus monkey demonstrate efficacy of odanacatib and differentiation from alendronate.

    Science.gov (United States)

    Cabal, Antonio; Jayakar, Richa Y; Sardesai, Swanand; Phillips, Eual A; Szumiloski, John; Posavec, Diane J; Mathers, Parker D; Savitz, Alan T; Scott, Boyd B; Winkelmann, Christopher T; Motzel, Sherri; Cook, Lynn; Hargreaves, Richard; Evelhoch, Jeffrey L; Dardzinski, Bernard J; Hangartner, Thomas N; McCracken, Paul J; Duong, Le T; Williams, Donald S

    2013-10-01

    Translational evaluation of disease progression and treatment response is critical to the development of therapies for osteoporosis. In this study, longitudinal in-vivo monitoring of odanacatib (ODN) treatment efficacy was compared to alendronate (ALN) in ovariectomized (OVX) non-human primates (NHPs) using high-resolution peripheral computed tomography (HR-pQCT). Treatment effects were evaluated using several determinants of bone strength, density and quality, including volumetric bone mineral density (vBMD), three-dimensional structure, finite element analysis (FEA) estimated peak force and biomechanical properties at the ultradistal (UD) radius at baseline, 3, 6, 9, 12, and 18 months of dosing in three treatment groups: vehicle (VEH), low ODN (2 mg/kg/day, L-ODN), and ALN (30 μg/kg/week). Biomechanical axial compression tests were performed at the end of the study. Bone strength estimates using FEA were validated by ex-vivo mechanical compression testing experiments. After 18months of dosing, L-ODN demonstrated significant increases from baseline in integral vBMD (13.5%), cortical thickness (24.4%), total bone volume fraction BV/TV (13.5%), FEA-estimated peak force (26.6%) and peak stress (17.1%), respectively. Increases from baseline for L-ODN at 18 months were significantly higher than that for ALN in DXA-based aBMD (7.6%), cortical thickness (22.9%), integral vBMD (12.2%), total BV/TV (10.1%), FEA peak force (17.7%) and FEA peak stress (11.5%), respectively. These results demonstrate a superior efficacy of ODN treatment compared to ALN at the UD radii in ovariectomized NHPs.

  19. DECOVALEX-THMC Project. Task B. Understanding and characterizing the excavation disturbed zone (EDZ). Final Report (EDZ Guidance Document) Characterising and Modelling the Excavation Damaged Zone (EDZ) in Crystalline Rocks in the Context of Radioactive Waste Disposal

    Energy Technology Data Exchange (ETDEWEB)

    Hudson, John A. (Imperial College and Rock Engineering Consultants (United Kingdom)); Baeckstroem, Ann; Lanru Jing (Royal lnstitute of Technology, Stockholm (Sweden)); Rutqvist, Jonny (Lawrence Berkeley National Laboratory (United States)) (eds.) (and others)

    2008-06-15

    This report is intended as a Guidance Document explaining current knowledge about the nature of and potential for thermo-hydro-mechanical-chemical modelling of the Excavation Damaged Zone (EDZ) around the excavations for an underground radioactive waste repository. In Part 1 of the report, the disturbances associated with excavation are explained together with reviews of Workshops that have been held on the subject. The manifold aspects of the EDZ are discussed under the three headings of the rock mass response to tunnelling, the influence of the excavation method, and EDZ characterisation methods. The evolution of the repository over thousands of years is qualitatively described via the subjects of time-dependent effects and stress redistribution, thermal effects, hydrogeological effects, and chemical effects. The first part of the document concludes with a discussion of uncertainties and limitations in measuring and characterising the EDZ. In Part 2 of the report, the results of a DECOVALEX research programme on modelling the EDZ are presented. Initially, the research involved the physical testing and computer modelling of the failure behaviour of a rock specimen in uniaxial compression. Four research teams used four different models to simulate the complete stress-strain curve for Aevroe granite from the Swedish Aespoe Hard Rock Laboratory. Conclusions are then made concerning the overall capabilities of these models. Subsequent research extended the work to computer simulation of the evolution of the repository using a 'wall block model' and a 'near-field model'. This included assessing the evolution of stress, failure and permeability and time dependent effects during repository evolution. In both sets of computer modelling, the types of codes used were an Elasto-Plastic Cellular Automaton (EPCA), the FRACOD boundary element (BEM) code with discrete fracture propagation, the THAMES finite element (FEM) code, and PFC, a distinct element

  20. Multiple-code benchmark simulation study of coupled THMC processesin the excavation disturbed zone associated with geological nuclear wasterepositories

    Energy Technology Data Exchange (ETDEWEB)

    Rutqvist, J.; Feng, X-T.; Hudson, J.; Jing, L.; Kobayashi, A.; Koyama, T.; Pan, P-Z.; Lee, H-S.; Rinne, M.; Sonnenthal, E.; Yamamoto, Y.

    2006-05-10

    An international, multiple-code benchmark test (BMT) studyis being conducted within the international DECOVALEX project to analysecoupled thermal, hydrological, mechanical and chemical (THMC) processesin the excavation disturbed zone (EDZ) around emplacement drifts of anuclear waste repository. This BMT focuses on mechanical responses andlong-term chemo-mechanical effects that may lead to changes in mechanicaland hydrological properties in the EDZ. This includes time-de-pendentprocesses such as creep, and subcritical crack, or healing of fracturesthat might cause "weakening" or "hardening" of the rock over the longterm. Five research teams are studying this BMT using a wide range ofmodel approaches, including boundary element, finite element, and finitedifference, particle mechanics, and elasto-plastic cellular automatamethods. This paper describes the definition of the problem andpreliminary simulation results for the initial model inception part, inwhich time dependent effects are not yet included.

  1. Stability assessment for underground excavations and key construction techniques

    CERN Document Server

    Zhu, Hanhua; Zhao, Yu; Niu, Fusheng

    2017-01-01

    This book examines how the state of underground structures can be determined with the assistance of force, deformation and energy. It then analyzes mechanized shield methods, the New Austrian tunneling method (NATM) and conventional methods from this new perspective. The book gathers a wealth of cases reflecting the experiences of practitioners and administrators alike. Based on statistical and engineering studies of these cases, as well as lab and field experiments, it develops a stability assessment approach incorporating a stable equilibrium, which enables engineers to keep the structure and surrounding rocks safe as long as the stable equilibrium and deformation compliance are maintained. The book illustrates the implementation of the method in various tunneling contexts, including soil-rock mixed strata, tunneling beneath operating roads, underwater tunnels, and tunnel pit excavation. It offers a valuable guide for researchers, designers and engineers, especially those who are seeking to understand the u...

  2. Pajarito Plateau archaeological survey and excavations. [Los Alamos Reservation

    Energy Technology Data Exchange (ETDEWEB)

    Steen, C.R.

    1977-05-01

    Los Alamos Scientific Laboratory lands were surveyed to locate pre-Columbian Indian ruins. The survey results will permit future construction to be planned so that most of the ancient sites in the area can be preserved. Indian occupation of the area occurred principally from late Pueblo III times (late 13th century) until early Pueblo V (about the middle of the 16th century). There are evidences of sporadic Indian use of the area for some 10,000 years. One Folsom point has been found, as well as many other archaic varieties of projectile points. Continued use of the region well into the historic period is indicated by pictographic art that portrays horses. In addition to an account of the survey, the report contains summaries of excavations made on Laboratory lands between 1950 and 1975.

  3. The Application of Foundation Pit Monitoring Technology to the Excavation

    Directory of Open Access Journals (Sweden)

    Qiu Jin

    2015-01-01

    Full Text Available The foundation pit monitoring plays an important role in the foundation pit supporting projects especially in those deep foundation pit projects. Through the whole monitoring of the foundation pit construction from the excavation to the backfill, we can learn about the forcing and deforming process of the foundation pit supporting system, and grasp the impact of external condition changes on the foundation pit. This paper takes a project in Jinan as an example to establish a specific monitoring program, and then conducts the analysis and evaluation of the monitoring data; the real-time grasp of the foundation pit deformation and internal force changes can help to further ensure the security status of the foundation pit, thus better guiding the construction.

  4. Infection control considerations during construction activities: land excavation and demolition.

    Science.gov (United States)

    Cheng, S M; Streifel, A J

    2001-10-01

    Because current trends in hospital restructuring in North America, amalgamations and mergers, and the aging of health care facilities, the need to restructure physical buildings has become greater. Hospital construction carries with it risks to patients. One key concern is the risk of aspergillosis associated with hospital construction. Infection control practitioners must consider some key factors when addressing land excavation and building demolition, which differ in some ways from construction that occurs within a health care facility. The key factors to consider are project concept, risk assessment of patients, procedures and environment, air quality, routes of entry and egress, soil management, conducting inspections, contingency planning, housekeeping, and lines of cooperation and communication with various stakeholders. Considering these areas will help ensure that health care facility personnel and the workers have exercised diligence in patient care.

  5. Shaft Excavation in Frozen Ground at Point 5

    CERN Document Server

    Osborne, J

    2000-01-01

    Construction work on the 112 MCHF civil engineering contract started at Point 5 in August 1998. The new surface buildings and underground structures are necessary to accommodate the CMS detector for the LHC Project. The principal underground works consist of two new shafts, two parallel caverns separated by a supporting pillar, and a number of small connection tunnels and service galleries. The two shafts are to be sunk through approximately 50 m of water-bearing moraine to the underlying molasse rock. From a number of possible construction methods, ground freezing of the moraine was considered to be most appropriate. The ground freezing is used to control the groundwater and to support temporarily the moraine during excavation and lining of the shafts. The aim of this paper is to present the ground-freezing technique and to discuss the advantages and disadvantages of the system in the light of its first few months of running on the Point 5 site.

  6. Groundwater flow modelling of the excavation and operational phases - Laxemar

    Energy Technology Data Exchange (ETDEWEB)

    Svensson, Urban (Computer-aided Fluid Engineering AB, Lyckeby (Sweden)); Rhen, Ingvar (SWECO Environment AB, Falun (Sweden))

    2010-12-15

    As a part of the license application for a final repository for spent nuclear fuel at Forsmark, the Swedish Nuclear Fuel and Waste Management Company (SKB) has undertaken a series of groundwater flow modelling studies. These represent time periods with different hydraulic conditions and the simulations carried out contribute to the overall evaluation of the repository design and long-term radiological safety. The modelling study reported here presents calculated inflow rates, drawdown of the groundwater table and upconing of deep saline water for different levels of grouting efficiency during the excavation and operational phases of a final repository at Laxemar. The inflow calculations were accompanied by a sensitivity study, which among other matters handled the impact of different deposition hole rejection criteria. The report also presents tentative modelling results for the duration of the saturation phase, which starts once the used parts of the repository are being backfilled

  7. Numerical investigation of fracture behavior of tunnel by excavation loading

    Institute of Scientific and Technical Information of China (English)

    ZHANG Zhe; TANG Chun-an; MA Tian-hui; DUAN Dong

    2007-01-01

    A rock failure process analysis model, RFPA2D code, a two-dimensional numerical code, were proposed. The code not only satisfied the global equilibrium, strain consistent and nonlinear constitutive relationship of rock and soil materials but also took into account the heterogeneous characteristics of rock materials at macroscopic and microscopically level. The failure behavior of tunnel could be simulated by this numerical model. The model could realistically simulate the fracture behavior of tunnel by excavation loading, strength limits, and post peak response for both tension and compression. As the proposed method was used to conduct the stability analysis of tunnel, the safety factor of tunnel was defined as the ratio of actual shear strength parameter to critical failure shear strength parameter. Not only the safety factor of tunnel with specific physics meaning can be obtained, but also the overall failure process and the location of failure surface may also be determined at the same time.

  8. Investigation of Hexavalent Chromium Flux to Groundwater at the 100-C-7:1 Excavation Site

    Energy Technology Data Exchange (ETDEWEB)

    Truex, Michael J.; Vermeul, Vincent R.; Fritz, Brad G.; Mackley, Rob D.; Horner, Jacob A.; Johnson, Christian D.; Newcomer, Darrell R.

    2012-11-16

    Deep excavation of soil has been conducted at the 100-C-7 and 100-C-7:1 waste sites within the 100-BC Operable Unit at the Department of Energy (DOE) Hanford Site to remove hexavalent chromium (Cr(VI)) contamination with the excavations reaching to near the water table. Soil sampling showed that Cr(VI) contamination was still present at the bottom of the 100-C-7:1 excavation. In addition, Cr(VI) concentrations in a downgradient monitoring well have shown a transient spike of increased Cr(VI) concentration following initiation of excavation. Potentially, the increased Cr(VI) concentrations in the downgradient monitoring well are due to Cr(VI) from the excavation site. However, data were needed to evaluate this possibility and to quantify the overall impact of the 100-C-7:1 excavation site on groundwater. Data collected from a network of aquifer tubes installed across the floor of the 100-C-7:1 excavation and from temporary wells installed at the bottom of the entrance ramp to the excavation were used to evaluate Cr(VI) releases into the aquifer and to estimate local-scale hydraulic properties and groundwater flow velocity.

  9. 29 CFR 570.68 - Occupations in excavation operations (Order 17).

    Science.gov (United States)

    2010-07-01

    ... 29 Labor 3 2010-07-01 2010-07-01 false Occupations in excavation operations (Order 17). 570.68 Section 570.68 Labor Regulations Relating to Labor (Continued) WAGE AND HOUR DIVISION, DEPARTMENT OF LABOR...-Being § 570.68 Occupations in excavation operations (Order 17). (a) Finding and declaration of fact....

  10. Deformations and damage to buildings adjacent to deep excavations in soft soils

    NARCIS (Netherlands)

    Korff, M.

    2009-01-01

    The objective of this study is to gain insight into mechanisms of soil-structure interaction for buildings adjacent to deep excavations and to find a reliable method to design and monitor deep excavations in urban areas with soft soil conditions. The research focuses on typical Dutch conditions. The

  11. Drill, baby, drill: the influence of woodpeckers on post-fire vertebrate communities through cavity excavation

    Science.gov (United States)

    Gina L. Tarbill; Patricia N. Manley; Angela M. White

    2015-01-01

    Several studies have addressed the importance of woodpeckers as ecological engineers in forests due to their excavation of cavities. Although research in green, unburned forests has identified the influence of different excavators on secondary use by cavity-dependent species, little is known about the relative importance of cavities created by woodpeckers in recently...

  12. Deformations and damage to buildings adjacent to deep excavations in soft soils

    NARCIS (Netherlands)

    Korff, M.

    2009-01-01

    The objective of this study is to gain insight into mechanisms of soil-structure interaction for buildings adjacent to deep excavations and to find a reliable method to design and monitor deep excavations in urban areas with soft soil conditions. The research focuses on typical Dutch conditions. The

  13. 29 CFR 1926.913 - Blasting in excavation work under compressed air.

    Science.gov (United States)

    2010-07-01

    ... 29 Labor 8 2010-07-01 2010-07-01 false Blasting in excavation work under compressed air. 1926.913... ADMINISTRATION, DEPARTMENT OF LABOR (CONTINUED) SAFETY AND HEALTH REGULATIONS FOR CONSTRUCTION Blasting and the Use of Explosives § 1926.913 Blasting in excavation work under compressed air. (a) Detonators...

  14. Physicochemical investigation of medieval ceramics from excavation site Novo Brdo

    Directory of Open Access Journals (Sweden)

    Čugalj Snežana S.

    2008-01-01

    Full Text Available Artefacts produced or treated at high temperatures provide information about manufacturing techniques. Well preserved ceramic objects are therefore excellent chronological markers as well as general markers of society development. In order to determine provenance of pottery fragments, archaeologists classify samples according to their physical characteristics, decoration and aesthetic style. However, a more objective multidisciplinary approach, based on undoubted results, is necessary to complete this study. In this work we have investigated 27 samples of medieval ceramics from excavation site Novo Brdo, using X-ray fluorescence (XRF, FTIR spectroscopy and X-ray powder diffraction (XRPD. Novo Brdo was large and rich mining and trading center of Serbia in XIV and XV century. A large number of ceramic samples found during the systematic excavation of this archaeological site allow good choice of samples for both destructive and nondestructive analysis. Combining results obtained by different experimental techniques, i.e. by FT-IR spectroscopy, after deconvolution of the spectra, and XRPD analysis, we have determined mineralogical composition and technology of production of investigated pottery. Estimated temperature of firing ranged from 800 to 900 °C, which is in agreement with the presence of high-temperature minerals like gehlenite and anorthite. Firing was preformed in the oxidation atmosphere since hematite, which is formed only in oxidation atmosphere, is detected in all investigated samples. Cross sections showed presence of defects and inhomogeneity of investigated ceramic, which indicates fast and incomplete firing procedure. All these findings indicate that investigated pottery was produced in the domestic workshops. The obtained results will be used to build up the National database for medieval ceramics as well as the database for the Balkan region.

  15. Bone scan

    Science.gov (United States)

    ... legs, or spine fractures) Diagnose a bone infection (osteomyelitis) Diagnose or determine the cause of bone pain, ... 2015:chap 43. Read More Broken bone Metabolism Osteomyelitis Review Date 12/10/2015 Updated by: Jatin ...

  16. Bone Cancer

    Science.gov (United States)

    Cancer that starts in a bone is uncommon. Cancer that has spread to the bone from another ... more common. There are three types of bone cancer: Osteosarcoma - occurs most often between ages 10 and ...

  17. Bone Diseases

    Science.gov (United States)

    Your bones help you move, give you shape and support your body. They are living tissues that rebuild constantly ... childhood and your teens, your body adds new bone faster than it removes old bone. After about ...

  18. Bone Markers

    Science.gov (United States)

    ... markers may be seen in conditions such as: Osteoporosis Paget disease Cancer that has spread to the bone (metastatic bone disease) Hyperparathyroidism Hyperthyroidism Osteomalacia in adults and rickets in children—lack of bone mineralization, ...

  19. PIXE multivariate statistics and OSL investigation for the classification and dating of archaeological pottery excavated at Tell Al-Rawda site, Syria

    Science.gov (United States)

    Bakraji, E. H.; Rihawy, M. S.; Castel, C.; Abboud, R.

    2015-03-01

    Particle Induced X-ray Emission (PIXE) technique has been utilised to study 48 Syrian ancient pottery fragments taken from excavations at Tell Al-Rawda site. Eighteen elements (Mg, Al, Si, P, S, K, Ca, Ti, Mn, Fe, Ni, Zn, As, Br, Rb, Sr, Y, and Pb) were determined. The elements concentrations have been processed using two multivariate statistical methods, to classify the pottery where one main group and other two small groups were defined. In addition, four samples from different places on the site were subjected to optically stimulated luminescence (OSL) dating. The average age obtained using a single aliquot regeneration (SAR) protocol was found to be 4350 ± 240 year.

  20. Interactions between remodelling, architecture and tissue properties in cancellous bone

    OpenAIRE

    Linden, Jacqueline

    2003-01-01

    textabstractThe aim of the research projects described in this thesis was to gain more insight in the regulation of bone remodeling and in the interactions between bone remodeling, architecture and bone tissue properties. The most striking changes during aging and osteoporosis take place in cancellous bone. For this reason, the research presented in this thesis focussed on bone remodeling in cancellous bone. We used computer modeling, finite element calculations and in vivo labeled bone speci...

  1. 固定桥基牙牙槽骨吸收三维有限元模型的建立%Construction of a three-dimensional finite element model of the absorbed alveolar bone of fixed partial denture abutments

    Institute of Scientific and Technical Information of China (English)

    陈艳; 吴娴; 张一岭; 张翼

    2011-01-01

    目的:通过建立左侧下颌后牙5单位固定桥双基牙侧牙槽骨吸收的有限元模型,为分析双基牙侧牙槽骨吸收对牙周膜应力的影响打下基础.方法:采用多层螺旋CT扫描技术与Mimics、Ansys软件相结合对88张层厚为0.6 mm的CT断层影像进行三维重建,在此基础上建立双基牙侧牙槽骨吸收模型.结果:建立了5单位固定桥有限元模型及双基牙侧牙槽骨吸收的有限元模型,包括牙齿、牙周膜、牙槽骨.结论:所建模型结构完整,单元划分精细,能够较精确地模拟牙槽骨吸收的实体状态,为加载后的基牙牙周膜应力分析提供基础.%AIM : To construct three-dimensional finite element models ( FEMs) of five-unit fixed partial denture of left mandible so as to analyze the effects of double abutments alveolar bone resorption on periodontal ligament stress.METHODS: Eighty-eight CT slice pictures (0.6mm in thickness) were treated with multislice helical computed tomography scanning technology, Mimics and Ansys Software to build the FEMs.Then the alveolar bone of double abutments inordinately absorbed models on the basis of the FEMs was built.RESULTS : A three-dimensional FEMs of five - unit fixed partial denture and al,veolar hone resorption of double abutments model were constructed, including teeth.periodontal ligaments and alveolar bone.CONCLUSION : The constructed models had the advantages of intact structure, precise elements and can simulate the natural situation of alveolar bone resorbtion and can provide basis for further research of periodontal ligament stress induced by loading.

  2. Effect of increased crown height on stress distribution in short dental implant components and their surrounding bone: A finite element analysis.

    Science.gov (United States)

    Bulaqi, Haddad Arabi; Mousavi Mashhadi, Mahmoud; Safari, Hamed; Samandari, Mohammad Mahdi; Geramipanah, Farideh

    2015-06-01

    Implants in posterior regions of the jaw require short dental implants with long crown heights, leading to increased crown-to-implant ratios and mechanical stress. This can lead to fracture and screw loosening. The purpose of this study was to investigate the dynamic nature and behavior of prosthetic components and preimplant bone and evaluate the effect of increased crown height space (CHS) and crown-to-implant ratio on stress concentrations under external oblique forces. The severely resorbed bone of a posterior mandible site was modeled with Mimics and Catia software. A second mandibular premolar tooth was modeled with CHS values of 8.8, 11.2, 13.6, and 16 mm. A Straumann implant (4.1×8 mm), a directly attached crown, and an abutment screw were modeled with geometric data and designed by using SolidWorks software. Abaqus software was used for the dynamic simulation of screw tightening and the application of an external load to the buccal cusp at a 75.8-degree angle with the occlusal plane. The distribution of screw load and member load at each step was compared, and the stress values were calculated within the dental implant complex and surrounding bone. During tightening, the magnitude and distribution of the preload and clamp load were uniform and equal at the cross section of all CHSs. Under an external load, the screw load decreased and member load increased. An increase in the CHS caused the corresponding distribution to become more nonuniform and increased the maximum compressive and tensile stresses in the preimplant bone. Additionally, the von Mises stress decreased at the abutment screw and increased at the abutment and fixture. Under nonaxial forces, increased CHS does not influence the decrease in screw load or increase in member load. However, it contributes to screw loosening and fatigue fracture by skewing the stress distribution to the transverse section of the implant. Copyright © 2015 Editorial Council for the Journal of Prosthetic Dentistry

  3. Methodology to determine skull bone and brain responses from ballistic helmet-to-head contact loading using experiments and finite element analysis.

    Science.gov (United States)

    Pintar, Frank A; Philippens, Mat M G M; Zhang, JiangYue; Yoganandan, Narayan

    2013-11-01

    The objective of the study was to obtain helmet-to-head contact forces from experiments, use a human head finite element model to determine regional responses, and compare outputs to skull fracture and brain injury thresholds. Tests were conducted using two types of helmets (A and B) fitted to a head-form. Seven load cells were used on the head-form back face to measure helmet-to-head contact forces. Projectiles were fired in frontal, left, right, and rear directions. Three tests were conducted with each helmet in each direction. Individual and summated force- and impulse-histories were obtained. Force-histories were inputted to the human head-helmet finite element model. Pulse durations were approximately 4 ms. One-third force and impulse were from the central load cell. 0.2% strain and 40 MPa stress limits were not exceeded for helmet-A. For helmet-B, strains exceeded in left, right, and rear; pressures exceeded in bilateral directions; volume of elements exceeding 0.2% strains correlated with the central load cell forces. For helmet-A, volumes exceeding brain pressure threshold were: 5-93%. All elements crossed the pressure limit for helmet-B. For both helmets, no brain elements exceeded peak principal strain limit. These findings advance our understanding of skull and brain biomechanics from helmet-head contact forces.

  4. Texture analyses of Sauropod dinosaur bones from Tendaguru

    Energy Technology Data Exchange (ETDEWEB)

    Pyzalla, A.R. [TU Wien, Institute of Material Science and Technology, Karlsplatz 13-308, A-1040 Vienna (Austria) and MPI fuer Eisenforschung GmbH, Max-Planck-Str. 1, D-40237 Duesseldorf (Germany)]. E-mail: pyzalla@mpie.de; Sander, P.M. [University of Bonn, Institute of Palaeontology, Nusseallee, D-53115 Bonn (Germany); Hansen, A. [TU Clausthal, Institute of Materials Science and Engineering. A, Structural Materials: Properties, Microstructure and Processingnd GKSS Research Centre Geesthacht GmbH, Geesthacht, Max-Planck-Str.1, D-21502 Geesthacht (Germany); Ferreyro, R. [TU Wien, Institute of Material Science and Technology, Karlsplatz 13-308, A-1040 Vienna (Austria); Yi, S.-B. [TU Clausthal, Institute of Materials Science and Engineering. A, Structural Materials: Properties, Microstructure and Processingnd GKSS Research Centre Geesthacht GmbH, Geesthacht, Max-Planck-Str.1, D-21502 Geesthacht (Germany); MPI fuer Eisenforschung GmbH, Max-Planck-Str. 1, D-40237 Duesseldorf (Germany); Stempniewicz, M. [TU Wien, Institute of Material Science and Technology, Karlsplatz 13-308, A-1040 Vienna (Austria); Brokmeier, H.-G. [TU Clausthal, Institute of Materials Science and Engineering. A, Structural Materials: Properties, Microstructure and Processingnd GKSS Research Centre Geesthacht GmbH, Geesthacht, Max-Planck-Str.1, D-21502 Geesthacht (Germany)

    2006-11-10

    The apatite texture of fossil Brachiosaurus brancai and Barosaurus africanus sauropod bones from the excavation site at Tendaguru, Tanzania, was characterized by neutron diffraction pole figures. The results obtained reveal predominantly <0 0 0 1>-fibre textures of the apatite; the fibre direction coincides with the longitudinal direction of the long bones of the skeletons. Neutron pole figures further indicate that other texture types may also be present. Texture strength is similar to dinosaur tendons and contemporary turkey tendon studied by others. Variations of texture strength across the bone wall cross-sections are not significantly large.

  5. Intelligent Risk Assessment for Dewatering of Metro-Tunnel Deep Excavations

    Directory of Open Access Journals (Sweden)

    X. W. Ye

    2012-01-01

    Full Text Available In recent years, China has been undergoing a metro railway construction boom in order to alleviate the urban traffic congestion problem resulting from the rapid urbanization and population growth in many metropolises. In the construction of metro systems, deep excavations and continuous dewatering for construction of the metro tunnels and stations remain a challenging and high risk task in densely populated urban areas. Intelligent computational methods and techniques have exhibited the exceptional talent in dealing with the complicated problems inherent in the deep excavation and dewatering practice. In this paper, an intelligent risk assessment system for deep excavation dewatering is developed and has been applied in the project of Hangzhou Metro Line 1 which is the first metro line of the urban rapid rail transit system in Hangzhou, China. The specific characteristics and great challenges in deep excavation dewatering of the metro-tunnel airshaft of Hangzhou Metro Line 1 are addressed. A novel design method based on the coupled three-dimensional flow theory for dewatering of the deep excavation is introduced. The modularly designed system for excavation dewatering risk assessment is described, and the field observations in dewatering risk assessment of the airshaft excavation of Hangzhou Metro Line 1 are also presented.

  6. Excavation on the Baozitou Shell- mound Site in Nanning City, Guangxi%广西南宁市豹子头贝丘遗址的发掘

    Institute of Scientific and Technical Information of China (English)

    中国社会科学院考古研究所广西工作队; 广西壮族自治区文物工作队; 南宁市博物馆

    2003-01-01

    The Baozitou site is an important riverbank shell-mound site in the Nanning area.Excavation there revealed substantial cultural and natural remains in good stratigraphieal order, including pottery, stone, bone and shell artifacts for daily use and implements of production, as well as bones of aquatic and terrestrial animals as remains of diet. The cultural deposits can be divided into two phases.Belonging to the Dingshishan culture on the whole, they provide new evidence for understanding its pe-riodization and distribution. In addition, vestiges of primitive ceramics were revealed on the site. As the first discovery of this sort in Guangxi and even in all South China, they are of great significance to studying into the making technology of proto-pottery, including the selection of clay and temper and thefiring method of products.

  7. The Restitution of “Çifte Hamam” in Ahlat According to Final Excavation Outcomes

    OpenAIRE

    AKSULU, Behiye; KARAMAĞARALI, Nakış; SAĞIROĞLU, Özlem

    2013-01-01

    The excavation of Ancient Ahlat City has started 45 years ago by Prof.Dr. Prof.Dr. Haluk Karamağaralı, and resumed under the chairmanship of Assoc. Prof. Dr. Nakıs Karamağaralı from 2005 to 2010. The excavations of old hamam were finalized at the end of the excavation season of 2010. The bath has two parts which arespecialized for women and men. Both parts has a cross shaped plan and has 2500 m2 area in total. The bath is a unique building found in Anatolia with four the iwans and eight halve...

  8. Research on Application of Regression Least Squares Support Vector Machine on Performance Prediction of Hydraulic Excavator

    Directory of Open Access Journals (Sweden)

    Zhan-bo Chen

    2014-01-01

    Full Text Available In order to improve the performance prediction accuracy of hydraulic excavator, the regression least squares support vector machine is applied. First, the mathematical model of the regression least squares support vector machine is studied, and then the algorithm of the regression least squares support vector machine is designed. Finally, the performance prediction simulation of hydraulic excavator based on regression least squares support vector machine is carried out, and simulation results show that this method can predict the performance changing rules of hydraulic excavator correctly.

  9. Mechanical effects of excavation rebound of arch dam bedrock and better concreting time of dam body

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    In high ground stress zone, rebound deformation of excavation of arch dam bedrock has a significant impact on the structural behavior, design and construction of arch dam. Based on the analysis of mechanical effects of excavation rebound, with both stress and deformation as two constraint conditions and deformation modulus as a controlling condition, the method to determine a better concreting time of dam body was put forward. All of these play an important guiding role in the excavation of dam bedrock and the construction of dam body.

  10. Modelling of an hydraulic excavator using simplified refined instrumental variable(SRIV)algorithm

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Instead of establishing mathematical hydraulic system models from physical laws usually done with the problems of complex modelling processes,low reliability and practicality caused by large uncertainties,a novel modelling method for a highly nonlinear system of a hydraulic excavator is presented.Based on the data collected in the excavator's arms driving experiments,a data-based excavator dynamic model using Simplified Refined Instrumental Variable(SRIV)identification and estimation algorithms is established.The validity of the proposed data-based model is indirectly demonstrated by the performance of computer simulation and the real machine motion control experiments.

  11. Large excavations and multi-disciplinary studies in deep underground laboratories

    Directory of Open Access Journals (Sweden)

    Wang Joseph S.Y.

    2014-01-01

    Full Text Available Since 2013, we have gathered some information on excavations recently completed, renovated, or planned in Asia, Europe, North and South America. In this review, we presented what we learned on both the large excavations and on multi-disciplinary studies. Large excavations in physics laboratories are driven by the needs associated with designing next generation of experiments to detect rare events. Some existing physics laboratories are interested to use available spaces for geo-sciences studies, including microbiological research for deep life. Summary of recent progress will be discussed.

  12. EXCAVATION OF PITS (CHANNELS BY IMPACT OF PULSE POWER LOADING

    Directory of Open Access Journals (Sweden)

    Anakhaev Koshkinbai Nazirovich

    2017-08-01

    Full Text Available The paper provides an innovative hydromechanical solution of the problem of profiles development of pits and channels by impact of pulse (blasting power load on a surface of homogeneous soil mass, for example, when excavating solid rocks, frozen soil, etc. Thus, soil would be considered as an ideal heavy liquid (disregarding its mechanical strength and plastic properties. The solution of this problem is achieved by the method of consecutive conformal mappings of physical flow region (in the form of Kirchhoff complex on the region of complex potential (in the form of a rectangle. Thus, the new technique of geometrical image generation of the latter in the presence in the flow region of a fixed point with discontinuous variations of pressure head-flow function and the direction of speed of flow and representation of an elliptic sine of Jacobi by means of elementary functions are used. The received analytical functional dependencies allow to determine an outline of a funnel of the soil ejection and all the required hydromechanical characteristics of flow (head-flow function, function of flow, speed of flow, etc.. Thus, the soil ejection funnel outline (for a benchmark problem completely coincides with subproduct of the known rigorous solution of Lavrentyev-Kuznetsov.

  13. Modeling and parameter estimation for hydraulic system of excavator's arm

    Institute of Scientific and Technical Information of China (English)

    HE Qing-hua; HAO Peng; ZHANG Da-qing

    2008-01-01

    A retrofitted electro-bydraulic proportional system for hydraulic excavator was introduced firstly. According to the principle and characteristic of load independent flow distribution(LUDV)system, taking boom hydraulic system as an example and ignoring the leakage of hydraulic cylinder and the mass of oil in it,a force equilibrium equation and a continuous equation of hydraulic cylinder were set up.Based On the flow equation of electro-hydraulic proportional valve, the pressure passing through the valve and the difference of pressure were tested and analyzed.The results show that the difference of pressure does not change with load, and it approximates to 2.0 MPa. And then, assume the flow across the valve is directly proportional to spool displacement andis not influenced by load, a simplified model of electro-hydraulic system was put forward. At the same time, by analyzing the structure and load-bearing of boom instrument, and combining moment equivalent equation of manipulator with rotating law, the estimation methods and equations for such parameters as equivalent mass and bearing force of hydraulic cylinder were set up. Finally, the step response of flow of boom cylinder was tested when the electro-hydraulic proportional valve was controlled by the stepcurrent. Based on the experiment curve, the flow gain coefficient of valve is identified as 2.825×10-4m3/(s·A)and the model is verified.

  14. Groundwater flow modelling of the excavation and operational phases - Forsmark

    Energy Technology Data Exchange (ETDEWEB)

    Svensson, Urban (Computer-aided Fluid Engineering AB, Lyckeby (Sweden)); Follin, Sven (SF GeoLogic AB, Taeby (Sweden))

    2010-07-15

    As a part of the license application for a final repository for spent nuclear fuel at Forsmark, the Swedish Nuclear Fuel and Waste Management Company (SKB) has undertaken a series of groundwater flow modelling studies. These represent time periods with different climate conditions and the simulations carried out contribute to the overall evaluation of the repository design and long-term radiological safety. The modelling study reported here presents calculated inflow rates, drawdown of the groundwater table and upconing of deep saline water for different levels of grouting efficiency during the excavation and operational phases of a final repository at Forsmark. The inflow calculations are accompanied by a sensitivity study, which among other matters handles the impact of parameter heterogeneity, different deposition hole rejection criteria, and the SFR facility (the repository for short-lived radioactive waste located approximately 1 km to the north of the investigated candidate area for a final repository at Forsmark). The report also presents tentative modelling results for the duration of the saturation phase, which starts once the used parts of the repository are being backfilled.

  15. Glass-metal objects from archaeological excavation: corrosion study

    Science.gov (United States)

    Greiner-Wronowa, Elżbieta; Zabiegaj, Dominika; Piccardo, Paolo

    2013-12-01

    This paper contributes to the investigations on history, technology, and degradation of middle age objects (metallic rings with mounted glass beads) recently excavated under the Main Square in Krakow (Poland). Moreover, they were discovered in soil layers differing by chemical composition and microclimate parameters. Historical material is indeed very limited in terms of quantity and sample size, and the following nondestructive analyses were applied: scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDXS), X-ray diffraction (XRD), and X-ray fluorescence spectroscopy (XRF). The glass and the metal were separately tested. Metallography on cross-sections (by both optical and scanning electron microscopy) was applied only on microfragments sampled from metallic rings. The achieved results pointed out how the local microclimate affected the degradation of the analyzed rings developing locally different corrosion processes. Each tested glass of "ring eye" shows a specific chemical composition. All glass pieces were covered by silica gel, and locally more advanced corrosion has been found.

  16. Inducible models of bone loss.

    Science.gov (United States)

    Doucette, Casey R; Rosen, Clifford J

    2014-12-11

    Bone is an essential organ that not only confers structural stability to the organism, but also serves as a reservoir for hematopoietic elements and is thought to affect systemic homeostasis through the release of endocrine factors as well as calcium. The loss of bone mass due to an uncoupling of bone formation and bone resorption leads to increased fragility that can result in devastating fractures. Further understanding of the effects of environmental stimuli on the development of bone disease in humans is needed, and they can be studied using animal models. Here, we present established and novel methods for the induction of bone loss in mice, including manipulation of diet and environment, administration of drugs, irradiation, and surgically induced hormone deficiency. All of these models are directly related to human cases, and thus, can be used to investigate the causes of bone loss resulting from these interventions. Copyright © 2014 John Wiley & Sons, Inc.

  17. Bone Densitometry (Bone Density Scan)

    Science.gov (United States)

    ... of DXA Bone Densitometry? What is a Bone Density Scan (DXA)? Bone density scanning, also called dual-energy x-ray absorptiometry ( ... is today's established standard for measuring bone mineral density (BMD). An x-ray (radiograph) is a noninvasive ...

  18. Bone marrow aspiration

    Science.gov (United States)

    Iliac crest tap; Sternal tap; Leukemia - bone marrow aspiration; Aplastic anemia - bone marrow aspiration; Myelodysplastic syndrome - bone marrow aspiration; Thrombocytopenia - bone marrow aspiration; Myelofibrosis - bone marrow aspiration

  19. Parametric Optimization and Prediction Tool for Lunar Surface Systems Excavation Tasks Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Honeybee Robotics proposes to develop a software tool for facilitating lunar excavation system trades in support of selecting an optimal architecture. This will...

  20. Bullialdus Crater: Excavation and Exposure of an Mg- or Alkali-Suite Pluton?

    Science.gov (United States)

    Klima, R. L.; Cahill, J. T. S.; Hagerty, J.; Lawrence, D.

    2012-07-01

    The reflectance spectra of Bullialdus Crater suggest an enhancement of OH^- relative to the surroundings. We examine local mineralogy and the spatial distribution of local Th and OH^- signatures to investigate the composition of the excavated pluton.

  1. 3D deformation effect and optimal excavated design of surface mine

    Institute of Scientific and Technical Information of China (English)

    WANG Shu-ren; FENG Ji-li

    2009-01-01

    The three-dimensional (3D) deformation effect of the slope engineering under the step-by-step excavation for the Antaibao surface mine was analyzed using the FLAC3D technique. An optimal excavated scheme with a relatively steeper slope angle of 47° instead of 30° was successfully implemented at the west wall in the geological section 73200 of the mine area, where the 3D effect of the nonlinear large deformation of the slope was taken into account. Based on the above research conclusion, put forward the countermeasures of shortening mining length, excavating by different regions, timely foot backfilling to protect the excavated slope, and monitoring and feedback adjustment by studying the nonlinear effect. The results show that these countermeasures are effective in controlling maximum deformation and increasing the stability of the slope.

  2. Method of Assessment of Hard Rock Workability using Bucket Wheel Excavators

    Science.gov (United States)

    Machniak, Łukasz; Kozioł, Wiesław

    2017-03-01

    A new hypothesis concerning a process of the mining solid rocks using bucket wheel excavators (BWE). Destroying of the rock mass structure is a result of breaking and not, as so far accepted, of cutting. This approach excludes, for the description of solid rock workability using bucket wheel excavators, used classifications based on individual linear or surface resistances of cutting. The possibility of a replacement mechanism for determining of the workability by bucket wheel excavators using rippers was assumed. On this basis, an innovative method for assessing the workability of solid rocks was developed, which is a combination of an derived empirical energy relationship LSE of breaking by tractor rippers from a compressive strength, a seismic wave velocity, a density of solid rock, and the modified classification of workability by bucket wheel excavators according to Bulukbasi (1991). The proposed method allows for multi-parameter assessment of the workability class based on the parameters that are independent variables in the specified dependencies.

  3. Energy-saving analysis of hydraulic hybrid excavator based on common pressure rail.

    Science.gov (United States)

    Shen, Wei; Jiang, Jihai; Su, Xiaoyu; Karimi, Hamid Reza

    2013-01-01

    Energy-saving research of excavators is becoming one hot topic due to the increasing energy crisis and environmental deterioration recently. Hydraulic hybrid excavator based on common pressure rail (HHEC) provides an alternative with electric hybrid excavator because it has high power density and environment friendly and easy to modify based on the existing manufacture process. This paper is focused on the fuel consumption of HHEC and the actuator dynamic response to assure that the new system can save energy without sacrificing performance. Firstly, we introduce the basic principle of HHEC; then, the sizing process is presented; furthermore, the modeling period which combined mathematical analysis and experiment identification is listed. Finally, simulation results show that HHEC has a fast dynamic response which can be accepted in engineering and the fuel consumption can be reduced 21% to compare the original LS excavator and even 32% after adopting another smaller engine.

  4. Performance predictions for mechanical excavators in Yucca Mountain tuffs; Yucca Mountain Site Characterization Project

    Energy Technology Data Exchange (ETDEWEB)

    Ozdemir, L.; Gertsch, L.; Neil, D.; Friant, J. [Colorado School of Mines, Golden, CO (United States). Earth Mechanics Inst.

    1992-09-01

    The performances of several mechanical excavators are predicted for use in the tuffs at Yucca Mountain: Tunnel boring machines, the Mobile Miner, a roadheader, a blind shaft borer, a vertical wheel shaft boring machine, raise drills, and V-Moles. Work summarized is comprised of three parts: Initial prediction using existing rock physical property information; Measurement of additional rock physical properties; and Revision of the initial predictions using the enhanced database. The performance predictions are based on theoretical and empirical relationships between rock properties and the forces-experienced by rock cutters and bits during excavation. Machine backup systems and excavation design aspects, such as curves and grades, are considered in determining excavator utilization factors. Instanteous penetration rate, advance rate, and cutter costs are the fundamental performance indicators.

  5. Calculation of the Chilling Requirement for Air Conditioning in the Excavation Roadway

    Directory of Open Access Journals (Sweden)

    Yueping Qin

    2015-10-01

    Full Text Available To effectively improve the climate conditions of the excavation roadway in coal mine, the calculation of the chilling requirement taking air conditioning measures is extremely necessary. The temperature field of the surrounding rock with moving boundary in the excavation roadway was numerically simulated by using finite volume method. The unstable heat transfer coefficient between the surrounding rock and air flow was obtained via the previous calculation. According to the coupling effects of the air flow inside and outside air duct, the differential calculation mathematical model of air flow temperature in the excavation roadway was established. The chilling requirement was calculated with the selfdeveloped computer program for forecasting the required cooling capacity of the excavation roadway. A good air conditioning effect had been observed after applying the calculated results to field trial, which indicated that the prediction method and calculation procedure were reliable.

  6. Re-Excavation of Seti First Tomb, Kv17, Luxor, Egypt

    National Research Council Canada - National Science Library

    Ayman HAMED

    2013-01-01

    .... Seti I tomb, is considered as the deepest opening in the valley, not mentioning the risk in re-excavation the tomb, harsh atmospheric conditions inside the tunnel, measured and monitored by author...

  7. Sub-Surface Excavation of Transient Craters in Porous Targets: Explaining the Impact Delay

    Science.gov (United States)

    Bowling, T. J.; Melosh, H. J.

    2012-03-01

    We numerically investigate the subsurface excavation of the transient crater in the earliest moments after the Deep Impact event. At high target porosities the crater remains hidden from observation long enough to explain the "impact delay."

  8. 探讨血清中微量元素与骨密度%Study on Trace Elements in Serum and Bone Mineral Density

    Institute of Scientific and Technical Information of China (English)

    邹毅; 李桂财; 叶茂; 冷华伟; 张玉峰

    2016-01-01

    Osteoporosis is the most common metabolic disease of the whole body, osteoporosis is mainly related to the intake of some minerals, excessive and uneven. It was found that the contents of trace elements in serum were mainly affected by calcium, zinc, iron, copper, phosphorus and magnesium. Therefore, the trace elements in the serum of osteoporosis prevention, diagnosis and treatment will have a very important role.%骨质疏松症是目前最常见的全身代谢疾病,骨质疏松症主要与某些矿物质的摄取不足、过量及不均衡有关。发现血清中的微量元素主要有钙、锌、铁、铜、磷、镁的含量影响着骨密度。因此,血清中微量元素在骨质疏松症的预防、诊断及治疗中将具有十分重要的作用。

  9. Critical Damage Analysis of WC-Co Tip of Conical Pick due to Coal Excavation in Mines

    Directory of Open Access Journals (Sweden)

    Saurabh Dewangan

    2015-01-01

    Full Text Available WC-Co based tools are widely used in the field of coal and rock excavation because of their unique combination of strength, hardness, and resistance to abrasive wear. Conical pick is one of the coal cutting tools. The tip of the pick is made of WC-Co material. As coal and rock are heterogeneous elements, they pose various constraints during excavation. As a result the tools wear out during the process. Other parameters like cutting techniques, tool orientation, and environmental conditions also affect the tool significantly. The wearing phenomenon greatly reduces the service life of the tools and thereby cuts down the production rate. To prevent such wearing process, it is important to investigate the different wear mechanisms in WC-Co. Simultaneously, there has to be an ongoing endeavour for the development of better quality WC-Co. This paper focuses on different wear mechanisms in a conical pick which has been used in a continuous miner machine for coal cutting. The worn out surface has been observed by using FE-SEM (field emission scanning electron microscopy and EDS (energy dispersive X-ray spectroscopy. The mechanisms, namely, coal/rock intermixing, cracking and crushing of WC grains, and adhesion of rock particles, have been predominantly investigated in this study. A little indication of corrosive decay in the WC grain has also been reported. The EDS has detected material concentration in a selected area or point of the worn-out surface. The spectrograph confirms the presence of coal/rock materials. Elements such as W, C, Ca, K, O, and Co have been mainly found in different concentrations at different positions.

  10. Excavated pulmonary nodules: an unusual clinical presentation of lung metastasis in two cases

    Directory of Open Access Journals (Sweden)

    Lalya Issam

    2010-06-01

    Full Text Available Abstract Background Excavated pulmonary metastasis are rare. We present two cases of excavated pulmonary nodules proved to be metastases from osteosarcoma and gallblader lymphoma. Case presentation The first one is 39-year-old man in whom cholecystectomy made the diagnosis of primary non-Hodgkin's lymphoma of the gallbladder. He presented in chest CT scan excavated nodules that had been biopsied and confirmed the diagnosis of non hodgkin lymphoma. He underwent 8 courses of chemotherapy CHOP 21 with complete remission. The second one is an 21 years old man who presented a right leg osteoblastic osteosarcoma with only excavated pulmonary nodules in extension assessment. He had 3 courses of polychemotherapy API (doxorubicin, platinum, and ifosfamide with partial response. Unfortunately, he died following a septic shock. Review of the literature shows that excavated pulmonary nodules as metastasis are rare but we should consider this diagnosis every time we are in front of a cancer. Chest computed tomography is the best diagnosis imaging that could make this diagnosis. Differential diagnosis between benign and malignant bullous lesions is important because surgical excision affects survival in some malignancies. Conclusions Although pulmonary nodules are the most common cancer metastasis, a differential diagnosis of a concurrent primary malignancy should always be considered every time we have excavated lesions, even in patients with known malignant disease. Thorough chest evaluation is important, as multiple primary malignancies may occur concomitantly.

  11. Recovery of Missing Persons in Cyprus: Heavy Equipment Methods and Techniques for Complex Well Excavations.

    Science.gov (United States)

    Ceker, Deren; Stevens, William D

    2015-11-01

    This technical note presents the methods and techniques developed by the Bi-communal Forensic Team (BCFT) of the Committee on Missing Persons in Cyprus (CMP) used to excavate and exhume the remains of missing persons, many of whom were buried in deep wells at sites across the island of Cyprus during the conflict period of the 1960s and 1970s. A total of 493 Turkish Cypriots and 1508 Greek Cypriots were officially reported missing by the two communities as a result of the conflict. Since the team's formation, in 2005, the BCFT has excavated 114 wells, resulting in the recovery of 195 missing individuals from 35 of these well excavations. The standard excavation approach used by the BCFT, especially for deep well recovery, consists of "ramp," "pocket," and "pool" components. These excavation features enable CMP archaeologists to excavate deep wells safely and efficiently while simultaneously permitting time for thorough documentation and unimpeded recovery of human remains. The team uses three variants of this approach to cope with the variety of geological, physical, and hydrological contexts faced in Cyprus' wells, including hard and soft landforms, the presence or absence of water, and limitations imposed by surrounding infrastructure. The "terracing", "double-ramp", and "single-ramp" variations are detailed with respect to the environmental contexts which prescribe their use. The BCFT's general procedures for human remains recovery and standard well safety protocols conclude the article.

  12. In situ experiments on width and evolution characteristics of excavation damaged zone in deeply buried tunnels

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    The seven long tunnels of Jinping II hydropower station are deeply buried.The width and evolution characteristics of excavation damaged zone(EDZ) are the key problem to the design of tunnels excavation and supports.In order to study this problem,several specific experimental tunnels with different overburden and geometric sizes were excavated at this site.Digital borehole camera,sliding micrometer,cross-hole acoustic wave equipment and acoustic emission apparatus were adopted.This paper introduced the comprehensive in situ experimental methods through pre-installed facilities and pre-drilled boreholes.Typical properties of the surrounding rock mass,including cracks,deformation,elastic wave and micro fractures,were measured during the whole process of the tunnel excavation.The width and characteristics of formation and evolution of tunnels EDZ were analyzed under different construction methods involving of TBM and drilling and blasting,the test tunnels were excavated by full-face or two benches.The relationships between EDZ and tunnel geometry sizes,overburden and excavation method were described as well.The results will not only contribute a great deal to the analysis of rock mass behavior in deeply buried rock mass,but also provide direct data for support design and rockburst prediction.

  13. Load transfer through the radiocarpal joint and the effects of partial wrist arthrodesis on carpal bone behaviour: a finite element study.

    Science.gov (United States)

    Gíslason, M K; Stansfield, B; Bransby-Zachary, M; Hems, T; Nash, D H

    2012-11-01

    A finite element model of the wrist was developed to simulate mechanical changes that occur after surgery of the wrist. After partial arthrodesis, the wrist will experience altered force transmission during loading. Three different types of partial arthrodesis were investigated - radiolunate, radioscaphoid, and radioscapholunate - and compared with the healthy untreated wrist. The results showed that the compressive forces on the radiocarpal joint decreased compared with the untreated wrist with both radiolunate and radioscaphoid fusions. The load transmission through the midcarpal joints varied depending on arthrodesis type. The forces in the extrinsic ligaments decreased with the fusion, most noticeably in the dorsal radiotriquetral ligament, but increased in the dorsal scaphotriquetral ligament. From the results of the study it can be concluded that the radioscapholunate fusion shows the most biomechanically similar behaviour out of the three fusion types compared with the healthy wrist. The modelling described in this paper may be a useful approach to pre-operative planning in wrist surgery.

  14. Techniques of Excavation and Documentation in the Terramara of St. Rosa of Poviglio, XXX Campaign: The Experience of Two Postgraduate Students

    Directory of Open Access Journals (Sweden)

    Nicolò Donati

    2014-08-01

    Full Text Available The excavations of terramara S. Rosa of Poviglio (RE, of the Middle-Late Bronze Age, arrived at the XXX campaign, have gained a large knowledge of the site, thanks to the contribution of many collaborators with different academic background. Multidisciplinarity of the research and attention at publishing and promotion of the area arise as essential elements of the project. It is worth to mention also the close-knit and competent team and the logistic organization well strengthened in time.

  15. Development of a Titanium Plate for Mandibular Angle Fractures with a Bone Defect in the Lower Border: Finite Element Analysis and Mechanical Test

    Directory of Open Access Journals (Sweden)

    Douglas Rangel Goulart

    2015-09-01

    Full Text Available Objectives: The aim of the present study was to develop a plate to treat mandibular angle fractures using the finite element method and mechanical testing. Material and Methods: A three-dimensional model of a fractured mandible was generated using Rhinoceros 4.0 software. The models were exported to ANSYS®, in which a static application of displacement (3 mm was performed in the first molar region. Three groups were assessed according to the method of internal fixation (2 mm system: two non-locking plates; two locking plates and a new design locking plate. The computational model was transferred to an in vitro experiment with polyurethane mandibles. Each group contained five samples and was subjected to a linear loading test in a universal testing machine. Results: A balanced distribution of stress was associated with the new plate design. This plate modified the mechanical behavior of the fractured region, with less displacement between the fractured segments. In the mechanical test, the group with two locking plates exhibited greater resistance to the 3 mm displacement, with a statistically significant difference when compared with the new plate group (ANOVA, P = 0.016. Conclusions: The new plate exhibited a more balanced distribution of stress. However, the group with two locking plates exhibited greater mechanical resistance.

  16. Study on trace element of Yue ware unearthed at different kiln sites

    Institute of Scientific and Technical Information of China (English)

    吴隽; 李家治; 郭景坤; 徐锴; 陈宝林

    1999-01-01

    The contents of trace element of Yue ware excavated in Shaoxing, Shanglinhu, Shangyu kiln sites and Hangzhou palace were analyzed by NAA technique. The data of trace element compositions were treated by statistical analysis. It is found that the sources of raw materials used in Shaoxing, Shanglinhu, Shangyu kiln sites are different and stable. Especially the discriminant function predicted for porcelain bodies provides high discriminatory power according to production site. It shows that Yue ware specimens excavated in Hangzhou palace were fired in Shanglinhu. It indicates the special function of trace element in the studies on site identification.

  17. The application of high resolution fluxgate gradiometery as an aid to excavation planning and strategy formulation

    Directory of Open Access Journals (Sweden)

    James Lyall

    1996-09-01

    Full Text Available The excavation of the Late Roman and Anglian settlement at West Heslerton, North Yorkshire, has been one of the largest excavations undertaken in England in the last twenty years. It has been the setting for a number of developments and experiments in the application of 'the new technology' to field archaeology. Parts of the site, which extended over c.20 Ha., proved to have high magnetic susceptibility and were ideally suited for magnetic prospection techniques. Feature visibility contrasts were, however, frequently low and therefore a series of experiments were undertaken using high resolution fluxgate gradiometer surveys following removal of the topsoil. The results of the high resolution surveys undertaken on the cleaned excavation surface proved highly successful in providing an enhanced pre-excavation plan, adding considerable detail to the surveys undertaken prior to the start of the excavation. The careful examination of the results, using G-Sys geographic data management software, which enabled the magnetic data, finds plots and digitised plans to be fully integrated, indicated areas where stratigraphic relationships could be tested and assisted in the development and re-definition of the excavation strategy as it progressed. Following initial small area tests in 1991, nearly two hectares were documented in this way during 1995 facilitating the completion of a targeted sampling operation which ensured the completion of the excavation within the limited budget available. The approach proved highly successful and offers great potential for use on sites which have a high magnetic susceptibility and are liable to large area destruction as occurs in the case of mineral extraction or subsoil ploughing operations.

  18. SLOPE STABILITY EVALUATION AND EQUIPMENT SETBACK DISTANCES FOR BURIAL GROUND EXCAVATIONS

    Energy Technology Data Exchange (ETDEWEB)

    MCSHANE DS

    2010-03-25

    After 1970 Transuranic (TRU) and suspect TRU waste was buried in the ground with the intention that at some later date the waste would be retrieved and processed into a configuration for long term storage. To retrieve this waste the soil must be removed (excavated). Sloping the bank of the excavation is the method used to keep the excavation from collapsing and to provide protection for workers retrieving the waste. The purpose of this paper is to document the minimum distance (setback) that equipment must stay from the edge of the excavation to maintain a stable slope. This evaluation examines the equipment setback distance by dividing the equipment into two categories, (1) equipment used for excavation and (2) equipment used for retrieval. The section on excavation equipment will also discuss techniques used for excavation including the process of benching. Calculations 122633-C-004, 'Slope Stability Analysis' (Attachment A), and 300013-C-001, 'Crane Stability Analysis' (Attachment B), have been prepared to support this evaluation. As shown in the calculations the soil has the following properties: Unit weight 110 pounds per cubic foot; and Friction Angle (natural angle of repose) 38{sup o} or 1.28 horizontal to 1 vertical. Setback distances are measured from the top edge of the slope to the wheels/tracks of the vehicles and heavy equipment being utilized. The computer program utilized in the calculation uses the center of the wheel or track load for the analysis and this difference is accounted for in this evaluation.

  19. Energy substrate used by workers of leaf-cutting ants during nest excavation

    Directory of Open Access Journals (Sweden)

    Roberto S. Camargo

    2013-12-01

    Full Text Available Energy substrate used by workers of leaf-cutting ants during nest excavation. In this study we aimed to ascertain whether leaf-cutting ant workers lose body reserves (fat or sugars as a function of nest excavation. For each treatment, we isolated 10 workers of Atta sexdens into two experimental groups, Control (C- without excavation and Soil (S- with excavation, which were kept for different time intervals (0, 24, 48 or 72 hours, totaling 700 tested workers. We then determined the concentration of soluble carbohydrates and total lipid content in them. The total carbohydrates were determined colorimetrically, based on the reaction between carbohydrates and sulfuric acid-phenol. For determination of lipids, the insects were immersed in organic solvent until they reached a constant weight. Our results showed that carbohydrates are consumed during nest excavation activities. In the experimental groups S24, S48 and S72, there was an average reduction of 5.82 (20.42%, 14.31 (44.96% and 13.27 (43.96% µ.mg-1 in soluble sugar when compared with the experimental groups that did not excavate. Furthermore, the lipids were not used during this activity. With respect to dry mass of the workers, their values were C0 = 8%, C24 = 10.4%, C48 = 9.2%, C72 = 10%, S24 = 9.2%, S48 = 8.7% and S72 = 8.5%. Our results show experimentally that the source of energy for nest excavation is carbohydrates, whereas lipids are conserved for other activities.

  20. Excavations at Kanjetar and Kaj on the Saurashtra Coast, Gujarat

    Digital Repository Service at National Institute of Oceanography (India)

    Gaur, A.S.; Sundaresh; Abhayan, G.S.; Joglekar, P.P.

    . Interestingly one bone could be identified to that of Genus Equus; but the species could not be securely identified. Six fragments of the domestic cat were recovered that belong to a single animal. There were no cut marks on all these fragments but all were... cakes, beads, etc. which indicates that Kanjetar was not an urban centre, and may be categorized as a village settlement. The role of the site in overseas trade is not securely identifiable. The pottery of Kanjetar closely resembles with the Prabhas...

  1. The influence of various occlusal materials on stresses transferred to implant-supported prostheses and supporting bone: a three-dimensional finite-element study.

    Science.gov (United States)

    Sevimay, Mujde; Usumez, Aslihan; Eskitascioglu, Gurcan

    2005-04-01

    The aim of this numerical analysis was to evaluate the amount and localization of stress that occurs with various materials used in implant-crown design under functional forces. Computer-aided design techniques and a finite-element stress analysis method were used for evaluation. A 4.1 x 10-mm implant placed in the mandibular second premolar area was simulated and analyzed. Simulation and analysis were performed with the use of COSMOS/M software and Pro/Engineer 2000i on a Dual Pentium III 1-GHz computer. Crown designs were as follows: porcelain fused to noble metal crown, porcelain fused to base metal crown, In-Ceram porcelain crown, and IPS Empress 2 porcelain crown. A 300-N vertical force was applied to the centric relation stop points of the crowns. The results of this study indicated that different types of restorative materials play an important role in the amount and distribution of the stresses in the superstructure and the implant. The highest stress values were observed in the IPS Empress 2 porcelain crown design (600 MPa). Porcelain fused to base metal and In-Ceram framework designs transferred less stress to abutment. Type of restorative materials used in implant crown designs are significant factors in the amount and distribution of the stresses on superstructure and implant under functional forces. Porcelain fused to base metal (149 MPa) and In-Ceram (173 MPa) crown designs induced higher von Mises stress values within the framework than porcelain fused to noble metal (108 MPa) and IPS Empress 2 (119 MPa) porcelain crown designs.

  2. Choice of rock excavation methods for the Swedish deep repository for spent nuclear fuel

    Energy Technology Data Exchange (ETDEWEB)

    Baeckblom, Goeran [Conrox, Stockholm (Sweden); Christiansson, Rolf [Swedish Nuclear Fuel and Waste Management Co., Stockholm (Sweden); Lagerstedt, Leif [SwedPower AB, Stockholm (Sweden)

    2004-09-01

    Choice of rock excavation methods will or may have implications for a number of issues like repository layout, long term and operational safety, environmental impact, design of and operation of transport vehicles and methodology for backfilling the repository before closure as well as effects on costs and schedules. To fully analyse the issues at hand related to selection of excavation methods, SKB organized a project with the objectives: To investigate and compare principal technical solutions for rock excavation, both methods that are used at present but also methods that may be feasible 10 years from now; To assess how the selection of excavation method influences the design and operation of the deep repository; To present a definition of the Excavation Damaged/Disturbed Zone and practical methods for measurements of EDZ; To present advantages and disadvantages with different excavation methods for the various tunnels and underground openings as a basis for selection of preferred excavation methods; To present the Design Justification Statement for the selection of particular excavation methods for the different tunnels and openings in the deep repository to underpin a decision on excavation method; and To present background data that may be required for the evaluation of the long term safety of the deep repository. Main alternatives studied are very smooth blasting, excavation with a tunnel-boring machine (TBM) and excavation with horizontal pull-reaming using more or less conventional raise-boring equipment. The detailed studies were carried through in co-operation with major suppliers and end-users of the technology. An observation in this study is that all excavation technologies are mature; no major breakthroughs are foreseen within a 10 year period but it is likely that for any technology selected, SKB would specifically fine-tune the design of the equipment and work procedures in view of requirements and site specific conditions. Excavation methods have

  3. Time-since-death and bone weathering in a tropical environment.

    Science.gov (United States)

    Ross, Ann H; Cunningham, Sarah L

    2011-01-30

    The structural breakdown of skeletal remains follows a lengthy decomposition process, progressing from the appearance of cracking along the bone to complete loss of shape and skeletal integrity, that can occur in as early as 6 years or as long as 30. The length of time a set of skeletal remains takes to decompose depends heavily upon its micro-environment, the local context in which decomposition agents act on remains. Critical changes in the micro-context can drastically increase or slow the process. The burial of remains below the surface has been found to effectively shut out many of the most destructive decaying agents, such as the natural elements and insect and animal activity. This causes an increase in the amount of time needed to breakdown the skeletal remains. A better understanding of the decomposition process in varying micro-contexts is important for the ability to correctly estimate time since burial. This can aid not only in understanding of archaeological remains, but also in the identification of individuals in modern forensic and human rights cases. This study details the observations made during the excavation and analysis of burials on the Isla de Coiba off the coast of Panama. The excavation took place during the summer 2003 in an effort to identify several individuals who were believed to be part of the 'disappeared', people who went missing and believed to have been murdered under orders by the Torrijos and Noriega military regimes. Through the fieldwork analysis a decomposition timeline, specific for the Coiba micro-environment, was created. This new set of stages can be used to estimate time since burial in other areas whose local context is similar to that found on Coiba.

  4. Current concepts:supplementation of tough bone elements magnesium, zinc, copper, and manganese, for the prevention and treatment of osteoporotic fractures%骨质疏松性骨折防治新概念:补充韧骨元素镁、锌、铜、锰

    Institute of Scientific and Technical Information of China (English)

    周建烈; 陈声

    2012-01-01

    Routine supplementation of calcium and vitamin D is effective for the prevention and treatment of osteoporosis, and it can reduce the rate of osteoporotic fractures further. Bone strength is determined by bone mineral density and bone quality. Bone mineral density depends on highly mineralized inorganic salts ( calcium, phosphorus, magnesium, etc. ). Bone quality is mainly composed of organic bone matrix collagen fibers. Trace elements, especially copper, manganese and zinc, are necessary for the synthesis of collagen. This paper mainly describes the role of magnesium, zinc, copper, and manganese in the prevention and treatment of osteoporosis and osteoporotic fractures. A new concept of supplementation of tough bone elements such as magnesium, zinc, copper, and manganese for the prevention and treatment osteoporotic fracture is proposed.%常规补充钙和维生素D可防治骨质疏松,进一步减少骨质疏松性骨折发病率.骨强度由骨密度和骨质量决定,骨密度由高度矿化的无机盐(钙、磷、镁等)组成,骨质量主要由有机骨基质胶原纤维组成,而胶原蛋白合成必需有微量元素参加,特别是铜、锰和锌.本文主要介绍镁、锌、铜、锰对骨质疏松症和骨质疏松性骨折防治的作用和临床研究,提出骨质疏松性骨折防治的新概念:补充韧骨元素镁、锌、铜、锰.

  5. Feasibility evaluation for excavation of Naghshe Jahan Square subway station by underground methods

    Institute of Scientific and Technical Information of China (English)

    Morteza Abdi Cherlo; Hamid Hashemolhosseini; Masoud Cheraghi; Saeed Mahdevari

    2013-01-01

    In recent years, in reaction to the increasing usage of urban areas, the excavation of underground spaces has been developed. One of the most challenging issues encountered by engineers is the construction of subway stations as large underground spaces at shallow depth with soft surrounding soils. In this paper, Naghshe Jahan Square subway station located in Isfahan, Iran, has been simulated by geomechanical finite difference method (FDM). This station is located under important historical structures. Therefore, the ground displacement and surface settlement induced by the excavation of the subway station should be strictly controlled. Many of such problems are affected by selected excavation method. For these reasons, different underground excavation methods associated with construction have been studied. In this study, sequential excavation method and large-diameter curved pipe roofing method are used and the numerical results of the two methods are compared. The presence of groundwater table obliges us to choose special techniques for the stability of the ground around the subway station during construction;hence compressed air and ground freezing techniques are utilized in the simulations of the subway station. Finally, after choosing appropriate support systems, the large-diameter curved pipe roofing method with 1.5 m spacing between curved pipes is proposed.

  6. Dig-face monitoring during excavation of a radioactive plume at Mound Laboratory, Ohio

    Energy Technology Data Exchange (ETDEWEB)

    Josten, N.E.; Gehrke, R.J.; Carpenter, M.V.

    1995-12-01

    A dig-face monitoring system consists of onsite hardware for collecting information on changing chemical, radiological, and physical conditions in the subsurface soil during the hazardous site excavation. A prototype dig-face system was take to Mount Laboratory for a first trial. Mound Area 7 was the site of historical disposals of {sup 232}Th, {sup 227}Ac, and assorted debris. The system was used to monitor a deep excavation aimed at removing {sup 227}Ac-contaminated soils. Radiological, geophysical, and topographic sensors were used to scan across the excavation dig-face at four successive depths as soil was removed. A 3-D image of the contamination plumes was developed; the radiation sensor data indicated that only a small portion of the excavated soil volume was contaminated. The spatial information produced by the dig-face system was used to direct the excavation activities into the area containing the {sup 227}Ac and to evaluate options for handling the separate {sup 232}Th plume.

  7. Digging Soil Experiments for Micro Hydraulic Excavators based on Model Predictive Tracking Control

    Science.gov (United States)

    Tomatsu, Takumi; Nonaka, Kenichiro; Sekiguchi, Kazuma; Suzuki, Katsumasa

    2016-09-01

    Recently, the increase of burden to operators and lack of skilled operators are the issue in the work of the hydraulic excavator. These problems are expected to be improved by autonomous control. In this paper, we present experimental results of hydraulic excavators using model predictive control (MPC) which incorporates servo mechanism. MPC optimizes digging operations by the optimal control input which is calculated by predicting the future states and satisfying the constraints. However, it is difficult for MPC to cope with the reaction force from soil when a hydraulic excavator performs excavation. Servo mechanism suppresses the influence of the constant disturbance using the error integration. However, the bucket tip deviates from a specified shape by the sudden change of the disturbance. We can expect that the tracking performance is improved by combining MPC and servo mechanism. Path-tracking controls of the bucket tip are performed using the optimal control input. We apply the proposed method to the Komatsu- made micro hydraulic excavator PC01 by experiments. We show the effectiveness of the proposed method through the experiment of digging soil by comparing servo mechanism and pure MPC with the proposed method.

  8. Study on test and preparation of load spectrum of hydraulic excavator

    Science.gov (United States)

    Zhang, Hong; Feng, Guodi; Zhang, Haijun; Wang, Xiaofeng; Zhang, Yingzhi

    2017-01-01

    Due to harsh working conditions, the components of hydraulic excavator are subject to large amount of alternating load and random load during the operation and they are seriously damaged. The test of load signal and preparation of load spectrum for the hydraulic excavator are studied in this paper. In the first place, pretreatment of filtering and noise reduction for load signal is conducted based on experimental test on site and experimental working condition analysis. After the load signal is processed in sections, distribution fitting is performed for information like mean amplitude after rain flow counting with the approach of probability statistics to get the probability distribution function for mean value and amplitude value. Finally the two dimensional load spectrum for mean amplitude is obtained and program spectrum loading solution of fatigue experiment is given. The study of load signal test and load spectrum preparation method for hydraulic excavator conducted in this paper is of great significance for clarification of load distribution of excavator and further reliability test of excavator.

  9. Numerical simulation for influence of excavation and blasting vibration on stability of mined-out area

    Institute of Scientific and Technical Information of China (English)

    XU Guo-yuan; YAN Chang-bin

    2006-01-01

    Dynamic analysis steps and general flow of fast lagrangian analysis of continua in 3 dimensions (FLAC3D) were discussed. Numerical simulation for influence of excavation and blasting vibration on stability of mined-out area was carried out with FLAC3D. The whole analytical process was divided into two steps, including the static analysis and the dynamic analysis which were used to simulate the influence of excavation process and blasting vibration respectively. The results show that the shape of right upper boundary is extremely irregular after excavation, and stress concentration occurs at many places and higher tensile stress appears. The maximum tensile stress is higher than the tensile strength of rock mass, and surrounding rock of right roof will be damaged with tension fracture. The maximum displacement of surrounding rock is 4.75 mm after excavation. However, the maximum displacement increases to 5.47 mm after the blasting dynamic load is applied. And the covering area of plastic zones expands obviously, especially at the foot of right upper slope. The analytical results are in basic accordance with the observed results on the whole. Damage and disturbance on surrounding rock to some degree are caused by excavation, while blasting dynamic load increases the possibility of occurrence of dynamic instability and destruction further. So the effective supporting and vibration reducing measures should be taken during mining.

  10. Analysis methods for excavation and tunneling; Kussaku koji ni kansuru kaiseki shuho

    Energy Technology Data Exchange (ETDEWEB)

    Kobayashi, A. [Iwate Univ., Morioka (Japan). Faculty of Agriculture

    1995-09-01

    The effect of groundwater in excavation is a problem regarding the issue of the excavation work. Accordingly, effective measures for spring water, deformation, stability and so forth may be expected if proper exploration of groundwater behavior in excavation is possible beforehand. However, highly reliable forecast is difficult in reality. The main reason for it is that it is not so easy to find out the nonuniformity of permeability of the ground. Seepage flow analysis method can be used if only the movement of groundwater is to be predicted, However, even for this, it is difficult to identify the prominent channel route in the ground beforehand. In existing analysis, only the appropriateness of prediction of whole flow out quantity from the excavation side can be discussed. In addition, finding out the sudden water gushing or escaped water beforehand is very difficult. However, prediction can be possible using numerical analysis in case of comparatively uniform ground. In this report, effect of groundwater behavior prediction on the analysis of excavation work is described and its evaluation method is outlined. 19 refs., 6 figs.

  11. Excavation of the Kangjiatun City-site in Beipiao City,Liaoning%辽宁北票市康家屯城址发掘简报

    Institute of Scientific and Technical Information of China (English)

    辽宁省文物考古研究所

    2001-01-01

    The Kangjiatun city-site is located 0.5km north of the Xiaobotai Gully at Kangjiatunvillage in Beipiao city, western Liaoning, lying on the second terrace on the southern bank of the DalingRiver, and belongs to the Lower Xiajiadian culture. In 1997-2000, it was continuously excavated in atotal area of 8,500 sq m, which resulted in the revelation of city walls, defensive projections along citywalls, a moat, and countyard walls, stone-paved roads, house-foundations, stone-built pits, “stone cases”, etc. in the city. According to stratigraphical evidence, including the superimposition and intrusion ofbuildings, the city-site can be divided into three phases. The excavation brought to light not only pottery,stone, bone and other artifacts, but also rather clear conditions of the layout and structure of the buildings in the city during the middle and late phases. Thus the site provides important data for studying theshape, layout and structure of city-sites in the Lower Xiajiadian culture, as well as human living and so-ial form in those cities.

  12. Biological reclamation of areas degraded after the excavation of lignite and copper ores

    Directory of Open Access Journals (Sweden)

    Agnieszka Mocek-Płóciniak

    2014-09-01

    Full Text Available The article contains basic assumptions of biological reclamation of the areas degraded in excavation of various industrial resources. Opencast or depth excavation always leads to intrusion in the natural environment. As a result, inner and outer spoil tips and post-flotation pits and containers – which are post-mining lands – are developed. After the excavation, such areas need a series of reclamation operations which incorporate technical and biological actions whose aim is to restore their environmental and utilitarian values. Reclamation of degraded areas should incorporate mainly actions which lead to preparation of grounds and enhancing their chemism, as well as biological operations targeted at the renovation of their biological activity (microbiological and enzymatic. A proper architecture of the spoil tip and the quality of post-mining ground ought to be developed in order to make post-industrial barrens change into farming or landscape areas and therefore, enhance the attractiveness of these transformed anthropogenic areas.

  13. GTP-based Integral Real-3D Spatial Model for Engineering Excavation GIS

    Institute of Scientific and Technical Information of China (English)

    WU Lixin; SHI Wenzhong

    2004-01-01

    Engineering excavation GIS (E2GIS) is a real-3D GIS serving for geosciences related to geo-engineering, civil engineering and mining engineering based on generalized tri-prism (GTP) model. As two instances of GTP model, G-GTP is used for the real-3D modeling of subsurface geological bodies, and E-GTP is used for the real-3D modeling of subsurface engineering excavations.In the light of the discussions on the features and functions of E2GIS, the modeling principles of G-GTP and E-GTP are introduced. The two models couple together seamlessly to form an integral model for subsurface spatial objects including both geological bodies and excavations. An object-oriented integral real-3D data model and integral spatial topological relations are discussed.

  14. A Study on Web Data Excavation%Web数据挖掘研究

    Institute of Scientific and Technical Information of China (English)

    程军锋

    2013-01-01

    With the rapid development of computer network, Web data is increasing rapidly. To unearth valuable data and knowledge from massive Web data is an important data excavation technology. This paper has an analysis of the contents and process of Web data excavation, and emphasizes the necessity of the algorithm of Web data excavation.%  随着计算机网络的快速发展,Web数据量呈快速增长,在海量的Web数据中发现有价值的数据和知识,是数据挖掘技术的重要应用。分析和研究Web数据挖掘的内容和过程,介绍Web数据挖掘的算法十分必要。

  15. Development of dust collection and removal technology of comprehensive mechanized excavation face

    Institute of Scientific and Technical Information of China (English)

    MA Heng; LI Yu-cheng; LIU Jian

    2008-01-01

    To solve the problem of excavation face dust control,the theory of dust removal after collection was put forward.Through a large number of theoretical and experimental researches,a new wind screen dust-collection system which was applied to comprehensive excavation face was developed.To set a wind dam in jet stream box,achieve the function of multi-stage and multiple-level regulation,lots of experimentation was carried out to obtain higher jet stream velocity with the minimum loss of energy.Experiments show that the slit width in the exports of wind screen dust-collection system should be 10 to 15 mm.For the general excavation roadway,after wind attenuation,the velocity can be greater than 3 m/s at the roof which meets the requirements of respirable dust control.

  16. Development of dust collection and removal technology of comprehensive mechanized excavation face

    Institute of Scientific and Technical Information of China (English)

    MA Heng; LI Yu-cheng; LIU Jian

    2008-01-01

    To solve the problem of excavation face dust control, the theory of dust removal after collection was put forward. Through a large number of theoretical and experimental researches, a new wind screen dust-collection system which was applied to comprehen-sive excavation face was developed. To set a wind dam in jet stream box, achieve the function of multi-stage and multiple-level regulation, lots of experimentation was carried out to obtain higher jet stream velocity with the minimum loss of energy. Experiments show that the slit width in the exports of wind screen dust-collection system should be 10 to 15 mm. For the general excavation roadway, after wind attenuation, the velocity can be greater than 3 m/s at the roof which meets the requirements of respirable dust control.

  17. Bronze and Iron Age Finds from Romuald's Cave, Istria: 2014 Excavation Season.

    Science.gov (United States)

    Janković, Ivor; Ahern, James C M; Mihelić, Sanjin; Premuzić, Zrinka

    2015-12-01

    Archaeological excavations in Romuald's Cave (Lim Channel, Istria, Croatia) have yielded evidence of human activity stretching back to the Middle Palaeolithic. This paper reports on recent Bronze Age/Early Iron Age discoveries uncovered during excavations as part of the Croatian National Science Foundation funded project: "Archaeological Investigations into the Late Pleistocene and Early Holocene of the Lim Channel, Istria". Fragmentary skeletal remains from at least two individuals were excavated, and a direct radiocarbon date from one of the remains is commensurate with a Bronze Age attribution. The recovered ceramics confirm this age attribution, although they range from the Middle Bronze Age to incipient Iron Age in character. Furthermore, the ceramics indicate that the human activities in Romuald's Cave were associated with the nearby settlements of Gradina and St. Martin.

  18. Optimum Design of Highway Excavation Slope Angle: Evidence from Dawu Section of Jingzhu Highway

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The optimum design of the highway excavation slope angle is one of the most important problems to the highway construction and to the slope improvement. The Dawu Section of Jingzhu (Beijing-Zhuhai) Highway is taken as an example to illustrate the study method for excavation slope angle design.The analysis of the engineering condition from different angles with different factors shows that the stability of the slope is calculated by using residual pushing force and the Sarma method. Then the sensitive analysis of the slope stability is conducted by using residual pushing force method. Finally, the optimum angle of design is presented on the precondition of ensuring the whole stability of slope and the economic reasonability. The study results show that the most sensitive factors are the shear strength parameter and t he seismic force, and that the optimum excavation slope angle is 60°.``

  19. Bone cutting.

    Science.gov (United States)

    Giraud, J Y; Villemin, S; Darmana, R; Cahuzac, J P; Autefage, A; Morucci, J P

    1991-02-01

    Bone cutting has always been a problem for surgeons because bone is a hard living material, and many osteotomes are still very crude tools. Technical improvement of these surgical tools has first been their motorization. Studies of the bone cutting process have indicated better features for conventional tools. Several non-conventional osteotomes, particularly ultrasonic osteotomes are described. Some studies on the possible use of lasers for bone cutting are also reported. Use of a pressurised water jet is also briefly examined. Despite their advantages, non-conventional tools still require improvement if they are to be used by surgeons.

  20. Teleservice for hydraulic excavators operating in open-cast mines; Teleservice bei Tagebau-Hydraulikbaggern

    Energy Technology Data Exchange (ETDEWEB)

    Poettker, A. [Terex Germany GmbH und Co. KG, Dortmund (Germany)

    2005-04-01

    Hydraulic excavators in open-cast mines are cost-intensive capital assets, which must be constantly observed during production in order to ensure availability. Teleservice is one way of reducing the service costs. As open-cast mines are generally developed in areas with a poor infrastructure, the excavators can be reliably reached only via satelite. Several network operators with different data transmission rates are suitable according to the required purpose. Satellite communication is expensive compared to the fixed network. New intelligent network topologies (MANET) are currently undergoing the first field tests. (orig.)

  1. Assessment of the Impact of Geomechanical Parameters Variability on Underground Excavations Stability Using Response Surface Method

    Science.gov (United States)

    Pytel, Witold; Świtoń, Joanna

    2013-03-01

    Recognition of properties of the rock mass surrounding a mineral deposit is particularly important for the mining operations at greater depths. Since the rock mass is usually not homogeneous, and its parameters have characteristics of randomness, underground workings safety issue should always be analysed taking into account the dispersion of the values of these parameters around their mean values. In order to assess the impact of geotechnical parameters uncertainty on the excavation stability one uses the appropriate statistical approach. In this paper, by analysing successive combinations of geomechanical parameters of the rock in the measured range, we examined the effect of their variability on risk of underground excavation instability using response surface method.

  2. Dynamic simulation and optimal control strategy for a parallel hybrid hydraulic excavator

    Institute of Scientific and Technical Information of China (English)

    Xiao LIN; Shuang-xia PAN; Dong-yun WANG

    2008-01-01

    The primary focus of this study is to investigate the control strategies of a hybrid system used in hydraulic excavators. First, the structure and evaluation target of hybrid hydraulic excavators are analyzed. Then the dynamic system model including batteries, motor and engine is built as the simulation environment to obtain control results. A so-called multi-work-point dynamic control strategy, which has both closed-loop speed PI (proportion integral) control and direct torque control, is proposed and studied in the simulation model. Simulation results indicate that the hybrid system with this strategy can meet the power demand and achieve better system stability and higher fuel efficiency.

  3. To the Optimal Use of Technological Capabilities of the Excavator – Dragline in Construction

    OpenAIRE

    Khayrullin Rustam

    2016-01-01

    The mathematical model of motion of system “boom on a turning platform – bifilar suspended bucket” was created. As a control function, we choose the moment of force relatively non-movable base. The length of suspension of the bucket is assumed to be constant. The bucket of excavator is suspended bifilar. The bucket and the arrow needs to be moved from initial rest final rest position. The results of solution of the problem of rapid movement of bucket of excavator - dragline are presented. The...

  4. National Advanced Drilling and Excavation Technologies Institute. Status report, March 1997

    Energy Technology Data Exchange (ETDEWEB)

    Peterson, C.

    1997-12-31

    The National Advanced Drilling and Excavation Technologies (NADET) program is intended to pool support, talent, and technologies of the industries dependent upon drilling and excavation technologies to initiate, coordinate, and sustain programs capable of developing substantial technological advances. The NADET Institute has been funded by the DOE Office of Geothermal Technologies and is now supporting seven projects aimed at advanced geothermal drilling technologies. The Institute seeks to broaden its base of funding and technological support from both government and industry sources. Encouraging progress has been made with the support of dues-paying industrial members and industrial sponsorship of a substantial drilling research study.

  5. CONSTANT WORK-POINT CONTROL FOR PARALLEL HYBRID SYSTEM WITH CAPACITOR ACCUMULATOR IN HYDRAULIC EXCAVATOR

    Institute of Scientific and Technical Information of China (English)

    ZHANG Yanting; WANG Qingfeng; XIAO Qing; FU Qiang

    2006-01-01

    Limitations of various accumulators in hybrid hydraulic excavator are analyzed. A program using capacitor as the accumulator based on constant work-point control is put forward. A simulating experimental system of hybrid construction machinery is established, and experimental study on constant work-point control for parallel hybrid system with capacitor accumulator is carried out using the pressure and flow rate derived from boom cylinder of hydraulic excavator in actual work as the simulating loads. A program of double work-point control is proposed and proved by further experiments.

  6. Excavation of the Zishan Site in Yuyao City,Zhejiang%浙江余姚市鲻山遗址发掘简报

    Institute of Scientific and Technical Information of China (English)

    浙江省文物考古研究所; 厦门大学历史系

    2001-01-01

    The Zishan site is an important Neolithic site in the Yaojiang River valley and belongs to the Hemudu culture. Noticeable achievements were obtained through excavation in 1996. The site contains deep deposits and rich remains, including tombs, ash-pits and wells. Beneath the eighth layer,remains of pile-dwellings have discovered in three units in an extensive area and can be reliably divided into two phases with respective technical features. Among the unearthed objects are many types of pottery articles, as well as a wide variety of wooden, bone and flint-chipped artifacts. The site corresponds to the Hemudu site in deposition, cultural aspect, cultural character and chronological attribution, and the new-discovered plentiful data enrich to a good extent our understanding of the contents of the Hemudu culture and have great importance to the study of the culture's developmental links and related problems.

  7. Excavation on the Xiaobalang Site in Huanan County, Heilongjiang%黑龙江桦南县小八浪遗址的发掘

    Institute of Scientific and Technical Information of China (English)

    黑龙江省佳木斯市文物管理站

    2002-01-01

    The Xiaobalang site lies on North Hill at Xiaobalang Village in Huanan County, Heilongjiang Province. In 1994, the Jiamusi Municipal Station for the Preservation of Ancient Monuments carried out there excavation in cooperation with Jilin University, and revealed an area of 1,450 sq m. The work brought to light eight house-foundations, six ash-pits and three tombs. The unearthed objects include various pottery vessels, stone tools, irons, bronzes and bone, horn and ivory artifacts, as well as “wuzhu” coins and animal remains. The site shows much similarity to the Guntuling site in cultural connotation and must have belonged to the Guntuling culture. It goes back roughly to the Han-Wei period according to 14C-dating and the features of the unearthed coins.

  8. 河北邢台市葛家庄10号墓的发掘%Excavation of Tomb 10 at Gejiazhuang, Xingtai City,Hebei

    Institute of Scientific and Technical Information of China (English)

    河北省文物研究所; 邢台市文物管理处

    2001-01-01

    This tomb is located north of Gejiazhuang village of Nandaguo township in the southwest of Xingtai city, Hebei, and was excavated in November 1993 to May 1994. It is a knife-shaped earth shaft. Although it was seriously robbed in ancient times, still a batch of important funeral objects was unearthed from the tomb pit. Among them are bronzes, jade and stone artifacts, lacquer-, bone-and shell-ware, and gold- and silver-covered articles, of which the bronzes include vessel details, weapons,chariot fittings, tools and musical instruments. Judged by its grave goods and inscriptions, the tomb must go back to the turn from the Spring-and-Autumn to the Warring States period. The chamber and coffin structure, funeral objects and size of the tomb suggest that the tomb-owner might have been an important minister of the Jin state.

  9. 新疆哈密市艾斯克霞尔墓地的发掘%Excavation of the Askchar Cemetery in Hami City, Xinjiang

    Institute of Scientific and Technical Information of China (English)

    新疆文物考古研究所; 哈密地区文物管理所

    2002-01-01

    This cemetery lies about 30km southwest of Wubao Township in Hami City, and was excavated in 1999 by the Xinjiang Institute of Cultural Relics and Archaeology. The work resulted in the revelation of 32 earth-pit tombs, mostly single burials in a flexed sideways position. The human remains are wrapped in leather coats and covered with leather masks on the face. Among the unearthed and collected objects, pottery and wooden wares come first in quantity, stone tools and bronzes next, and bone and horn artifacts, woolen textiles and leather articles are still smaller in number. The burial ground is roughly identical with the Yanbulake and Wubao cemeteries in tomb form and grave goods, and must have been of the Yanbulake culture. The tombs date from 3000BP and belong to the Bronze Age.

  10. 河北邢台县东先贤遗址发掘简报%Excavation on the Dongxianxian Site in Xingtai County, Hebei

    Institute of Scientific and Technical Information of China (English)

    河北省文物研究所

    2002-01-01

    In March~April 1996, the Hebei Provincial Institute of Cultural Relics excavated the Dongxianxian site in an area of 550 sq m. The vestiges discovered there are mainly ash-pits, and also pottery-making kilns, tombs, etc. The ash-pits have a circular, oval, rectangular or irregular mouth. The objects unearthed are largely pottery; the rest include stone, bone, horn and shell artifacts. In the pottery, gray sandy ware comes first in amount, then gray clay one. The vessels belong principally to the types of li tripod, gui food container, basin, yah steamer, jia tripod, jar and urn. Analyses of the stratigraphical evidence of the site and the shape of the pottery show that the site can be roughly divided into two phases. The first phase dates approximately from the turn between the Shang and the Zhou period, while the second, from the early Western Zhou.

  11. Nest Enlargement in Leaf-Cutting Ants: Relocated Brood and Fungus Trigger the Excavation of New Chambers

    Science.gov (United States)

    Römer, Daniela; Roces, Flavio

    2014-01-01

    During colony growth, leaf-cutting ants enlarge their nests by excavating tunnels and chambers housing their fungus gardens and brood. Workers are expected to excavate new nest chambers at locations across the soil profile that offer suitable environmental conditions for brood and fungus rearing. It is an open question whether new chambers are excavated in advance, or will emerge around brood or fungus initially relocated to a suitable site in a previously-excavated tunnel. In the laboratory, we investigated the mechanisms underlying the excavation of new nest chambers in the leaf-cutting ant Acromyrmex lundi. Specifically, we asked whether workers relocate brood and fungus to suitable nest locations, and to what extent the relocated items trigger the excavation of a nest chamber and influence its shape. When brood and fungus were exposed to unfavorable environmental conditions, either low temperatures or low humidity, both were relocated, but ants clearly preferred to relocate the brood first. Workers relocated fungus to places containing brood, demonstrating that subsequent fungus relocation spatially follows the brood deposition. In addition, more ants aggregated at sites containing brood. When presented with a choice between two otherwise identical digging sites, but one containing brood, ants' excavation activity was higher at this site, and the shape of the excavated cavity was more rounded and chamber-like. The presence of fungus also led to the excavation of rounder shapes, with higher excavation activity at the site that also contained brood. We argue that during colony growth, workers preferentially relocate brood to suitable locations along a tunnel, and that relocated brood spatially guides fungus relocation and leads to increased digging activity around them. We suggest that nest chambers are not excavated in advance, but emerge through a self-organized process resulting from the aggregation of workers and their density-dependent digging behavior

  12. Nest enlargement in leaf-cutting ants: relocated brood and fungus trigger the excavation of new chambers.

    Science.gov (United States)

    Römer, Daniela; Roces, Flavio

    2014-01-01

    During colony growth, leaf-cutting ants enlarge their nests by excavating tunnels and chambers housing their fungus gardens and brood. Workers are expected to excavate new nest chambers at locations across the soil profile that offer suitable environmental conditions for brood and fungus rearing. It is an open question whether new chambers are excavated in advance, or will emerge around brood or fungus initially relocated to a suitable site in a previously-excavated tunnel. In the laboratory, we investigated the mechanisms underlying the excavation of new nest chambers in the leaf-cutting ant Acromyrmex lundi. Specifically, we asked whether workers relocate brood and fungus to suitable nest locations, and to what extent the relocated items trigger the excavation of a nest chamber and influence its shape. When brood and fungus were exposed to unfavorable environmental conditions, either low temperatures or low humidity, both were relocated, but ants clearly preferred to relocate the brood first. Workers relocated fungus to places containing brood, demonstrating that subsequent fungus relocation spatially follows the brood deposition. In addition, more ants aggregated at sites containing brood. When presented with a choice between two otherwise identical digging sites, but one containing brood, ants' excavation activity was higher at this site, and the shape of the excavated cavity was more rounded and chamber-like. The presence of fungus also led to the excavation of rounder shapes, with higher excavation activity at the site that also contained brood. We argue that during colony growth, workers preferentially relocate brood to suitable locations along a tunnel, and that relocated brood spatially guides fungus relocation and leads to increased digging activity around them. We suggest that nest chambers are not excavated in advance, but emerge through a self-organized process resulting from the aggregation of workers and their density-dependent digging behavior

  13. Nest enlargement in leaf-cutting ants: relocated brood and fungus trigger the excavation of new chambers.

    Directory of Open Access Journals (Sweden)

    Daniela Römer

    Full Text Available During colony growth, leaf-cutting ants enlarge their nests by excavating tunnels and chambers housing their fungus gardens and brood. Workers are expected to excavate new nest chambers at locations across the soil profile that offer suitable environmental conditions for brood and fungus rearing. It is an open question whether new chambers are excavated in advance, or will emerge around brood or fungus initially relocated to a suitable site in a previously-excavated tunnel. In the laboratory, we investigated the mechanisms underlying the excavation of new nest chambers in the leaf-cutting ant Acromyrmex lundi. Specifically, we asked whether workers relocate brood and fungus to suitable nest locations, and to what extent the relocated items trigger the excavation of a nest chamber and influence its shape. When brood and fungus were exposed to unfavorable environmental conditions, either low temperatures or low humidity, both were relocated, but ants clearly preferred to relocate the brood first. Workers relocated fungus to places containing brood, demonstrating that subsequent fungus relocation spatially follows the brood deposition. In addition, more ants aggregated at sites containing brood. When presented with a choice between two otherwise identical digging sites, but one containing brood, ants' excavation activity was higher at this site, and the shape of the excavated cavity was more rounded and chamber-like. The presence of fungus also led to the excavation of rounder shapes, with higher excavation activity at the site that also contained brood. We argue that during colony growth, workers preferentially relocate brood to suitable locations along a tunnel, and that relocated brood spatially guides fungus relocation and leads to increased digging activity around them. We suggest that nest chambers are not excavated in advance, but emerge through a self-organized process resulting from the aggregation of workers and their density

  14. Secondary Excavation of the Koguryo Mountain Castle at ,Shitaizi,Shenyang City,Liaoning%辽宁沈阳市石台子高句丽山城第二次发掘简报

    Institute of Scientific and Technical Information of China (English)

    沈阳市文物考古工作队

    2001-01-01

    The secondary excavation of the Shitaizi mountain castle was carried out on the basis of the first digging. It covered an area of 450 sq m. The recorded remains include the excavated sites of the northwestern, eastern, southern and southwestern city-gates, the reservoir and officers-mustering terrace vestiges known through trial diggings, and the drains discovered at the northwestern and eastern city-gates. Among the unearthed objects are pottery (the urn, jar, dish, basin, fu cauldron, bowl, dou stemmed vessel, vessel cover, spindle whorl and disc), bronzes (the buckle, arrowhead and plaque), irons(the arrowhead, armor plate, nail, paring knife, awl, hook, ring, axe, door-nail, door-axle and its base,and cap-like cover), stone tools (the perforated stone, grindstone, spindle whorl and adze) and bone and antler artifacts. The present excavation indicates that this mountain castle was twice damaged by fire.The city-gate structural members found on the gate-sites, such as iron-cast door-leaves, door-axles and their bases, rivets and loops, are all discovered for the first time at Koguryo mountain castle and provide very valuable material for studying the shape and structure of mountain-castle gates in that period.

  15. Elemental distribution in human femoral head

    Energy Technology Data Exchange (ETDEWEB)

    Santos, C., E-mail: catia.santos@itn.pt [Dep. Física, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica (Portugal); Centro de Física Nuclear da Universidade de Lisboa, 1649-003 Lisboa (Portugal); Campus Tecnológico e Nuclear, IST/CTN, Universidade Técnica de Lisboa E.N. 10, 2686-953 Sacavém (Portugal); Fonseca, M. [Dep. Física, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica (Portugal); Centro de Física Nuclear da Universidade de Lisboa, 1649-003 Lisboa (Portugal); Universidade Europeia|Laureate International Universities, 1500-210 Lisboa (Portugal); Corregidor, V. [Campus Tecnológico e Nuclear, IST/CTN, Universidade Técnica de Lisboa E.N. 10, 2686-953 Sacavém (Portugal); Silva, H. [Dep. Física, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica (Portugal); Centro de Física Nuclear da Universidade de Lisboa, 1649-003 Lisboa (Portugal); Campus Tecnológico e Nuclear, IST/CTN, Universidade Técnica de Lisboa E.N. 10, 2686-953 Sacavém (Portugal); Luís, H.; Jesus, A.P. [Dep. Física, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica (Portugal); Centro de Física Nuclear da Universidade de Lisboa, 1649-003 Lisboa (Portugal); and others

    2014-07-15

    Osteoporosis is the most common bone disease with severe symptoms and harmful effects on the patient quality of life. Because abnormal distribution and concentration of the major and trace elements may help to characterize the disease, ion beam analysis is applied to the study of bone samples. Proton Induced X-ray Emission and Elastic Backscattering Spectrometry are applied for qualitative and quantitative analysis of an osteoporotic bone sample, for the determination of the Ca/P ratio and analysis of the distribution of major and trace elements. The analysis was made both in trabecular and cortical bone and the results are in agreement with the information found in literature.

  16. Elemental distribution in human femoral head

    Science.gov (United States)

    Santos, C.; Fonseca, M.; Corregidor, V.; Silva, H.; Luís, H.; Jesus, A. P.; Branco, J.; Alves, L. C.

    2014-07-01

    Osteoporosis is the most common bone disease with severe symptoms and harmful effects on the patient quality of life. Because abnormal distribution and concentration of the major and trace elements may help to characterize the disease, ion beam analysis is applied to the study of bone samples. Proton Induced X-ray Emission and Elastic Backscattering Spectrometry are applied for qualitative and quantitative analysis of an osteoporotic bone sample, for the determination of the Ca/P ratio and analysis of the distribution of major and trace elements. The analysis was made both in trabecular and cortical bone and the results are in agreement with the information found in literature.

  17. Microgravity and bone cell mechanosensitivity

    Science.gov (United States)

    Klein-Nulend, J.; Bacabac, R. G.; Veldhuijzen, J. P.; Van Loon, J. J. W. A.

    2003-10-01

    The capacity of bone tissue to alter its mass and structure in response to mechanical demands has long been recognized but the cellular mechanisms involved remained poorly understood. Bone not only develops as a structure designed specifically for mechanical tasks, but it can adapt during life toward more efficient mechanical performance. Mechanical adaptation of bone is a cellular process and needs a biological system that senses the mechanical loading. The loading information must then be communicated to the effector cells that form new bone or destroy old bone. The in vivo operating cell stress derived from bone loading is likely the flow of interstitial fluid along the surface of osteocytes and lining cells. The response of bone cells in culture to fluid flow includes prostaglandin (PG) synthesis and expression of prostaglandin G/H synthase inducible cyclooxygenase (COX-2). Cultured bone cells also rapidly produce nitric oxide (NO) in response to fluid flow as a result of activation of endothelial nitric oxide synthase (ecNOS), which enzyme also mediates the adaptive response of bone tissue to mechanical loading. Earlier studies have shown that the disruption of the actin-cytoskeleton abolishes the response to stress, suggesting that the cytoskeleton is involved in cellular mechanotransduction. Microgravity, or better near weightlessness, is associated with the loss of bone in astronauts, and has catabolic effects on mineral metabolism in bone organ cultures. This might be explained as resulting from an exceptional form of disuse under near weightlessness conditions. However, under near weightlessness conditions the assembly of cytoskeletal elements may be altered since it has been shown that the direction of the gravity vector determines microtubular pattern formation in vivo. We found earlier that the transduction of mechanical signals in bone cells also involves the cytoskeleton and is related to PGEZ production. Therefore it is possible that the

  18. Monitoring the Excavation Damaged Zone in Opalinus clay by three dimensional reconstruction of the electrical resistivity in the Mont Terri gallery G-04

    Science.gov (United States)

    Lesparre, N.; Adler, A.; Nicollin, F.; Gibert, D.; Nussbaum, C.

    2012-04-01

    The characteristics of opalinus clay have been studied in the last years for its capacity to retain radionuclide transport as a low permeable rock. This formation presents thereby suitable properties for hosting repository sites of radioactive waste. The Mont Terri underground rock laboratory (Switzerland) has been excavated in opalinus clay layer in order to develop experiences improving the knowledge on the physico-chemical properties of the rock. The study of electrical properties furnishes information on the rock structure, its anisotropy and the changes of these properties with time (Nicollin et al., 2010 ; Thovert et al., 2011). Here the three dimensional reconstruction of the electrical resistivity aims at monitoring the temporal evolution of the excavation damaged zone. Three rings of electrodes have been set-up around the gallery and voltage is measured between two electrodes while a current is injected between two others (Gibert et al., 2006). Measurements have been achieved from July 2004 until April 2008 before, during and after the excavation of the gallery 04. In this study we develop a computational approach to reconstruct three dimensional images of the resistivity in the vicinity of the electrodes. A finite element model is used to represent the complex geometry of the gallery. The measurements inferred from a given resistivity distribution are estimated using the software EIDORS (Adler and Lionheart, 2006), this constitutes the forward problem. The reconstruction of the media resistivity is then implemented by fitting the estimated to the measured data, via the resolution of an inverse problem. The parameters of this inverse problem are defined by mapping the forward problem elements into a coarser mesh. This allows to reduce drastically the number of unknowns and so increases the robustness of the inversion. The inversion is executed with the conjugate gradient method regularised by an analysis of the Jacobian singular values. The results show an

  19. Probabilistic analysis of soil: Diaphragm wall friction used for value engineering of deep excavation, north/south metro Amsterdam

    NARCIS (Netherlands)

    Buykx, S.M.; Delfgaauw, S.; Bosch, J.W.

    2009-01-01

    The excavation of deep building pits often requires a check against failure by uplift of low permeability ground layers below excavation level. Whenever the weight of these soil layers is less than the pore-water pressure underneath, measures to resist buoyancy are to be considered. The measures mos

  20. Finite Element Analysis on Crural Bone Stress Changes after Partial Fibulectomy%有限元分析部分腓骨切除对小腿骨受力的影响

    Institute of Scientific and Technical Information of China (English)

    李韵; 贺西京; 李栋才

    2001-01-01

    部分腓骨切除广泛运用于腓骨移植术及腓骨肿瘤、外伤等治疗中。经过术后随访及离体力学实验分析,许多作者认为切除侧小腿的并发症是值得重视的问题,但仍存在争论。本研究采用计算机有限元模拟技术,对部分腓骨切除前后该侧下肢腓骨的受力情况进行分析。结果发现:切除术明显改变了腓骨内应力分布及分载能力,从而影响了距骨内外侧的应力分布,降低了踝关节的稳定性,并对临床观察到的并发症表现作了解释和讨论。%Partial fibulectomy is widely used in fibula transplantation and the treatment of fibular tumor and injury. After follow-up surveys and biomechanical experiments, many authors believe it is important to pay attention to the postoperative complications in leg,which now still remains in dispute. For the first time finite element analysis is used to find out the mechanical characteristics of crural bone before and after partial fibulectomy. Our results show that resection would alter significantly the stress distribution in tibia, fibula and the medial & lateral parts of talus, so influent the ankle joint stability. Causes of postoperative complications were also discussed.

  1. Screw-bone finite element models for screw pullout simulation%螺钉-骨抗拔出力试验有限元模型的建立与验证

    Institute of Scientific and Technical Information of China (English)

    严亚波; 裴国献; 桑宏勋; 马真胜; 雷伟

    2013-01-01

    Objective To establish screw-bone finite element (FE) models for screw pullout simulation.Methods A pedicle screw model with a diameter of 6.5 mm,a model of screw-low density porous foam and a model of screw-high density porous foam were established and validated against the published data.Next,a screw-bone model was established and imported into the ANSYS software for FE simulation to study the dynamic bone responses during screw pullout according to the criteria set by American Association for Testing Materials (ASTM).A velocity loading of 0.01 mm/s with a maximum displacement of 2.7 mm was applied on the screw.For validation,the screw-foam models with 2 different densities were used for comparison of the pullout forces with the experimental data published.Results In validation,the predicted pullout forces were 2028.8 N in the high density foam model and 607.0 N in the low density foam model,respectively.They were in good agreement with the data of Hashemi et al.(2132.5 ± 119.3 N and 688.2 ±91.4 N,respectively).The load-displacement curves in the FE models were similar to the published (1.8 mm versus 1.5mm).In the simulation of screw pullout,the areas around the crew changed in volume in the process of pullout.Conclusion The dynamic screw-bone FE model established and validated by the present study can be used in simulation of pullout of pedicle screws to study mechanical bone responses to the pullout.%目的 建立螺钉-骨抗拔出力试验的动态有限元模型,模拟螺钉的拔出过程. 方法 基于螺钉的国标尺寸,建立直径为6.5 mm的椎弓根螺钉模型,并建立对应骨组织的高密度和低密度多孔泡沫三维模型进行验证,最后建立螺钉-骨模型研究螺钉拔出过程中骨骼的动态响应.在Ansys中对三维模型进行网格划分,并按照美国材料试验协会(ASTM)标准对螺钉进行拔出力加载分析.拔出方向为轴向拔出,拔出速度为0.01 mm/s.建立模型后,对模型进行加载计算并与

  2. Establishing time-dependent model of deformation modulus caused by bedrock excavation rebound by inverse analysis method

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Rock rebound relaxation deformation,or even rock burst,caused by the excavation of dam base and abutment or high rock slope affects their stability and results in the fall of mechanical properties of the rock.So an inverse analysis method was proposed in this paper to establish the time-dependent model of deformation modulus caused by excavation rebound.The basic principle is based on the combination of observed data of the excavation rebound deformation of dam abutment or rock slope,and the calculated rebound deformation by FEM under ground stress at the corresponding time in the excavation process.The norm of the residuals of observed data and calculated data are taken as the objective function.Accordingly,the time-dependent model of bedrock deformation modulus can be established.The method displays its significance in the design of excavation,construction and operation management of dam base and high slope.

  3. Property and provenance study of fancy celadon samples excavated from the Noble Burials of the Yue State at Hongshan, China

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    The Noble Burials of the Yue State at Hongshan in Wuxi City with many fancy burial objects were excavated by Archaeology Institute of Jiangsu Province and Xishan District Committee for Administration of Cultural Relics of China. It was appraised as one of the ten major archaeological excavations in 2004. Some precious ceramic samples excavated from this site are very important for studying the development history of Chinese ceramics, especially for studying the origin of porcelain. With the cooperation of Archaeology Institute of Nanjing Museum, the ceramic samples excavated from the Noble Burials of the Yue State at Hongshan were collected and systematically analyzed. Compared with the celadon samples produced in Yue-kiln site during later Eastern Han Dynasty (25–220 A.D.), some important topics such as the provenance and properties of the ceramic samples excavated from the Noble Burials of the Yue State at Hongshan were deeply studied.

  4. Investigation of a Medieval Pilgrim Burial Excavated from the Leprosarium of St Mary Magdalen Winchester, UK

    Science.gov (United States)

    Tucker, Katie; Filipek-Ogden, Kori; Montgomery, Janet; Cameron, Jamie; O’Connell, Tamsin; Evans, Jane; Marter, Phil; Taylor, G. Michael

    2017-01-01

    We have examined the remains of a Pilgrim burial from St Mary Magdalen, Winchester. The individual was a young adult male, aged around 18–25 years at the time of death. Radiocarbon dating showed the remains dated to the late 11th–early 12th centuries, a time when pilgrimages were at their height in Europe. Several lines of evidence in connection with the burial suggested this was an individual of some means and prestige. Although buried within the leprosarium cemetery, the skeleton showed only minimal skeletal evidence for leprosy, which was confined to the bones of the feet and legs. Nonetheless, molecular testing of several skeletal elements, including uninvolved bones all showed robust evidence of DNA from Mycobacterium leprae, consistent with the lepromatous or multibacillary form of the disease. We infer that in life, this individual almost certainly suffered with multiple soft tissue lesions. Genotyping of the M.leprae strain showed this belonged to the 2F lineage, today associated with cases from South-Central and Western Asia. During osteological examination it was noted that the cranium and facial features displayed atypical morphology for northern European populations. Subsequently, geochemical isotopic analyses carried out on tooth enamel indicated that this individual was indeed not local to the Winchester region, although it was not possible to be more specific about their geographic origin. PMID:28125649

  5. Indicating street vitality in excavated towns: Spatial configurative analyses applied to Pompeii

    NARCIS (Netherlands)

    Van Nes, A.

    2014-01-01

    The aim of this contribution is to show how it is possible to indicate degrees of street life and economic attractiveness in excavated towns through micro- and macro-spatial configurative analyses. The space syntax method is able to calculate the spatial configuration of built environments and

  6. Stability calculation method of slope reinforced by prestressed anchor in process of excavation.

    Science.gov (United States)

    Li, Zhong; Wei, Jia; Yang, Jun

    2014-01-01

    This paper takes the effect of supporting structure and anchor on the slope stability of the excavation process into consideration; the stability calculation model is presented for the slope reinforced by prestressed anchor and grillage beam, and the dynamic search model of the critical slip surface also is put forward. The calculation model of the optimal stability solution of each anchor tension of the whole process is also given out, through which the real-time analysis and checking of slope stability in the process of excavation can be realized. The calculation examples indicate that the slope stability is changed with the dynamic change of the design parameters of anchor and grillage beam. So it is relatively more accurate and reasonable by using dynamic search model to determine the critical slip surface of the slope reinforced by prestressed anchor and grillage beam. Through the relationships of each anchor layout and the slope height of various stages of excavation, and the optimal stability solution of prestressed bolt tension design value in various excavation stages can be obtained. The arrangement of its prestressed anchor force reflects that the layout of the lower part of bolt and the calculation of slope reinforcement is in line with the actual. These indicate that the method is reasonable and practical.

  7. Numerical investigation of the convex effect on the behavior of crossing excavations

    Institute of Scientific and Technical Information of China (English)

    Min ZHANG; Xing-hua WANG; Guang-cheng YANG; You WANG

    2011-01-01

    A 3D numerical model considering the soil-structure interaction is presented in this paper to examine the ground movement and internal force during the construction of Qingdao North Metro Station,China with a special focus on the convex effect of the crossing excavation.The influence of intersection angles and soil resilience characteristics on deformation behavior is discussed,and the suitability of two alternative constitutive models applied in excavation simulation is also considered.The analysis results show that a notable convex effect appears to be associated with the crossing excavation,and the intersection is the key area requiring special attention.The displacements at the corner decrease with increasing crossing angles.The axial loads of struts along the retaining pile wall are unequal,and the values near the cross section are generally larger than the average loads of the left-sided ones.The modified Cam-Clay (MCC) model,which is capable of describing the loading-unloading criterion and identifying the stiffness difference of strain hardening between loading and unloading,can yield a relatively high accuracy of estimation for the behavior of excavations in comparison to the Mohr-Coulomb (MC) model.Furthermore,slight soil deformation resilience after unloading can reduce the ground surface settlement and enhance the ground stability.

  8. Improving work load and comfort of operators on modified hydraulic excavators in rail road maintenance

    NARCIS (Netherlands)

    Grinten, M.P. van der; Houtman, I.I.D.

    2000-01-01

    In small-scale projects of mechanized maintenance of rail roads special equipped hydraulic excavators (HE) are used in several maintenance tasks. One task concerns the exchange of the old crossbars and ballast under the rails by new materials (MCE-task). This task requires high precision of the HE-o

  9. Over-excavation forecast of underground opening by using Bayes discriminant analysis method

    Institute of Scientific and Technical Information of China (English)

    GONG Feng-qiang; LI Xi-bing; ZHANG Wei

    2008-01-01

    A method to forecast the over-excavation of underground opening by using the Bayes discriminant analysis(BDA) theory was presented. The Bayes discriminant analysis theory was introduced. Based on an engineering example, the factors influencing the over-excavation of underground opening were taken into account to build a forecast BDA model, and the prior information about over-excavation of underground opening was also taken into consideration. Five parameters influencing the over-excavation of opening, including 2 groups of joints, 1 group of layer surface, extension and space between structure faces were selected as geometric parameters. Engineering data in an underground opening were used as the training samples. The cross-validation method was introduced to verify the stability of BDA model and the ratio of mistake-discrimination was equal to zero after the BDA model was trained. Data in an underground engineering were used to test the discriminant ability of BDA model. The results show that five forecast results are identical with the actual situation and BDA can be used in practical engineering.

  10. Stabilizing coal quality when developing deposits of complex structure using bucket wheel excavators

    Energy Technology Data Exchange (ETDEWEB)

    Belyakov, Yu.I.; Pushkin, S.P. (Kievskii Inzhenerno-Stroitel' nyi Institut (USSR))

    1989-07-01

    Using the example of the complex geological conditions found in the Ehkibastuz basin, describes a method of computerized simulation that may be used to forecast the ash content of coal. This method may be applied to vertical and horizontal coal extraction and takes into account the excavator's technical parameters, the load carrying capacity of the rail wagons used to transport the coal, the geological condition of the seam layers, and the type of bucket wheel excavator used. Based on the results of investigation into variations in ash content, claims that the coefficient of variation in the ash content of coal transported by rail wagons to electric power plants may be reduced by selecting technology according to the seam's angle of dip. Recommends that excavators with a wheel diameter of 10-13 m (e.g. the SPs(k)-2000 or EhRShRD-5000) be used on angles of dip of 0-50 degrees and excavators with a wheel diameter of 6-7 m (e.g. the EhRP-1250) be used on angles of dip of 50-90 degrees. Replacing the EhRP-1250 by the ERShRD-5000 in the Bogatyr' coal mine would reduce the coefficient of ash content variation by 40%. 4 refs.

  11. Seismic analysis of nailed vertical excavation using pseudo-dynamic approach

    Science.gov (United States)

    Sarangi, Piyush; Ghosh, Priyanka

    2016-12-01

    An attempt has been made to study the behavior of nailed vertical excavations in medium dense to dense cohesionless soil under seismic conditions using a pseudo-dynamic approach. The effect of several parameters such as angle of internal friction of soil ( ϕ), horizontal ( k h) and vertical ( k v) earthquake acceleration coefficients, amplification factor ( f a), length of nails ( L), angle of nail inclination ( α) and vertical spacing of nails ( S v) on the stability of nailed vertical excavations has been explored. The limit equilibrium method along with a planar failure surface is used to derive the formulation involved with the pseudo-dynamic approach, considering axial pullout of the installed nails. A comparison of the pseudo-static and pseudo-dynamic approaches has been established in order to explore the effectiveness of the pseudo-dynamic approach over pseudo-static analysis, since most of the seismic stability studies on nailed vertical excavations are based on the latter. The results are expressed in terms of the global factor of safety (FOS). Seismic stability, i.e., the FOS of nailed vertical excavations is found to decrease with increase in the horizontal and vertical earthquake forces. The present values of FOS are compared with those available in the literature.

  12. Natural Diet of Coral-Excavating Sponges Consists Mainly of Dissolved Organic Carbon (DOC)

    NARCIS (Netherlands)

    Mueller, B.; de Goeij, J.M.; Vermeij, M.J.A.; Mulders, Y.; van der Ent, E.; Ribes, M.; van Duyl, F.C.

    2014-01-01

    Coral-excavating sponges are the most important bioeroders on Caribbean reefs and increase in abundance throughout the region. This increase is commonly attributed to a concomitant increase in food availability due to eutrophication and pollution. We therefore investigated the uptake of organic

  13. Stepwise excavation may enhance pulp preservation in permanent teeth affected by dental caries

    DEFF Research Database (Denmark)

    Bjørndal, Lars

    2011-01-01

    ARTICLE TITLE AND BIBLIOGRAPHIC INFORMATION: Ways of enhancing pulp preservation by stepwise excavation-a systematic review. Hayashi M, Fujitani M, Yamaki C, Momoi Y. J Dent 2011;39(2):95-107. Epub 2010 Dec 3. REVIEWER: Lars Bjørndal, DDS, PhD, Dr Odont PURPOSE/QUESTION: To determine the clinical...

  14. Simulating the time-dependent behaviour of excavations in hard rock

    CSIR Research Space (South Africa)

    Malan, DF

    2002-10-01

    Full Text Available associated with using viscoelastic theory to simulate the time-dependent behaviour of hard rock, a viscoelastic convergence solution for the incremental enlargement of a tabular excavation is discussed. Data on the time dependent deformation of a tunnel...

  15. National advanced drilling and excavation technologies program: Summary of third meeting of interested Federal agencies

    Energy Technology Data Exchange (ETDEWEB)

    None

    1993-12-07

    The purpose of the meeting was: (1) to discuss a proposal by the Massachusetts Institute of Technology (MIT) outlining a National Advanced Drilling and Excavation Technologies Program, (2) to brief participants on events since the last meeting, and (3) to hear about drilling research activities funded by the Department of Energy. The meeting agenda is included as Attachment B.

  16. The 2010-2011 excavation season at Al Zubarah, north-west Qatar

    DEFF Research Database (Denmark)

    Richter, Tobias; al-Naimi, Faisal; Yeomans, Lisa

    2012-01-01

    This paper briefly summarizes the results of the 2010–2011 archaeological fieldwork at the late eighteenth–twentieth-century abandoned city of al-Zubarah in north-west Qatar. The excavations in five areas inside the town, covering courtyard houses, a suq, a palatial compound, and a midden are dis...

  17. Subsurface Tiltmeter Observations of Solid Earth Tides and Rock Excavation in Northeastern Illinois

    Science.gov (United States)

    Lancelle, C.; Volk, J.; Fratta, D.; Wang, H. F.

    2013-12-01

    Tiltmeter arrays in the Main Injector Neutrino Oscillation Search (MINOS) Near Detector Hall at Fermilab and the Lafarge - Conco Mine record solid earth tides and mechanical unloading due to excavation. The arrays are located approximately 100 meters underground in the Galena-Platteville dolomite in Northeastern Illinois. Just off of the MINOS Near Detector Hall a new cavern was excavated to house the Off-axis Neutrino Appearance Experiment (NOvA) program near detector. The recorded excavation response in the MINOS Near Detector Hall due to the NOvA cavern excavation is approximately thirteen times a point-load estimated response calculated using laboratory-determined properties. This discrepancy is likely due to variations in Young's Modulus in the rock in a field versus laboratory scale, although seasonal effects causing long term trends in the data could be part of this response. Amplitudes of measured solid earth tides differ from the amplitudes of theoretical solid earth tides by up to 40 percent for both arrays. This is likely due to a local heterogeneity or discontinuity.

  18. The Li(f)e of the Self: Missing Persons and Auto/Archeological Excavations

    Science.gov (United States)

    Burdick, Jake

    2014-01-01

    This article describes and enacts a process of autobiographical inquiry, auto/archeology, which seeks to address problematic confluences of memory and identity in reconstructing one's historical narrative. Drawing on curriculum theory and Lacanian psychoanalysis, the author describes a process of excavation in which understandings of a prior…

  19. Onshore excavation at Bet Dwarka Island, in the Gulf of Kachchh, Gujarat

    Digital Repository Service at National Institute of Oceanography (India)

    Gaur, A.S.; Sundaresh

    and bullock carts might reflect a past reality. Radiocarbon dates of the lowest level of BDK-II is 2040- 1860 years B.P. Excavation of the present Dwarka suggests that around the Christian Era the sea level was lower than the present (Sankalia 1966...

  20. Excavation-drier method of energy-peat extraction reduces long-term climatic impact

    Energy Technology Data Exchange (ETDEWEB)

    Silvan, N.; Silvan, K.; Laine, J. [Finnish Forest Research Inst., Parkano (Finland)], e-mail: niko.silvan@metla.fi; Vaisanen, S.; Soukka, R. [Lappeenranta Univ.of Techology (Finland)

    2012-11-01

    Climatic impacts of energy-peat extraction are of increasing concern due to EU emissions trading requirements. A new excavation-drier peat extraction method has been developed to reduce the climatic impact and increase the efficiency of peat extraction. To quantify and compare the soil GHG fluxes of the excavation drier and the traditional milling methods, as well as the areas from which the energy peat is planned to be extracted in the future (extraction reserve area types), soil CO{sub 2}, CH{sub 4} and N{sub 2}O fluxes were measured during 2006-2007 at three sites in Finland. Within each site, fluxes were measured from drained extraction reserve areas, extraction fields and stockpiles of both methods and additionally from the biomass driers of the excavation-drier method. The Life Cycle Assessment (LCA), described at a principal level in ISO Standards 14040:2006 and 14044:2006, was used to assess the long-term (100 years) climatic impact from peatland utilisation with respect to land use and energy production chains where utilisation of coal was replaced with peat. Coal was used as a reference since in many cases peat and coal can replace each other in same power plants. According to this study, the peat extraction method used was of lesser significance than the extraction reserve area type in regards to the climatic impact. However, the excavation-drier method seems to cause a slightly reduced climatic impact as compared with the prevailing milling method. (orig.)

  1. ZEDEX - A study of damage and disturbance from tunnel excavation by blasting and tunnel boring

    Energy Technology Data Exchange (ETDEWEB)

    Emsley, S. [Golder Associates, Maidenhead (United Kingdom); Olsson, Olle; Stenberg, L. [Swedish Nuclear Fuel and Waste Co., Figeholm (Sweden); Alheid, H.J. [Federal Inst. for Geosciences and Natural Resources, Hannover (Germany); Falls, S. [Queens Univ., Kingston, ON (Canada)

    1997-12-01

    The objectives of the ZEDEX project were to understand the mechanical behaviour of the excavation disturbed zone (EDZ) with respect to its origin, character, magnitude of property change, extent and its dependence on excavation method. Excavation with normal smooth blasting, blasting with low shock explosives and tunnel boring were studied. The drifts are located at Aespoe at a depth of 420 m, the profiles are circular and 5 m in diameter. The results have shown that there is a damaged zone, close to the drift wall dominated by changes in rock properties which are irreversible, and that there is a disturbed zone beyond the damaged zone that is dominated by changes in stress state and mainly reversible. There is no distinct boundary between the two zones. The results from ZEDEX indicate that the role of the EDZ as a preferential pathway to radionuclide transport is limited to the damaged zone. The extent of the damaged zone can be limited through application of appropriate excavation methods. By limiting the extent of the damaged zone it should also be feasible to block pathways in the damaged zone by plugs placed at strategic locations 68 refs, 92 figs, 31 tabs

  2. Study on passive earth pressure acting on the embedment of an earth retaining wall for braced excavation work in cohesive soil; Nenseido jiban ni okeru kussaku dodomeheki neirebu no judo doatsu ni kansuru kenkyu

    Energy Technology Data Exchange (ETDEWEB)

    Nakamura, H. [Pacific Consultants K.K., Tokyo (Japan); Hirashima, K. [Yamanashi University, Yamanashi (Japan). Faculty of Engineering

    1995-12-15

    Passive earth pressure exerts a great influence on the stress and deformation of earth retaining walls in braced excavation. To calculate this pressure, conventional ultimate earth pressure equation, or Rankine-Resals and Coulomb`s equation, are currently applied respectively to cohesive and sandy soil. However, these intentional equation to determine passive earth pressure do not adequately take into account the excavation width during work and the shearing resistance on the earth retaining wall surface. This paper deals with cohesive soil only, deriving a calculation equation for passive earth pressure, which takes into account excavation width and the shearing resistance of the earth retaining wall surface. Then, constants in this equation are determined using the calculation results obtained from the finite element method with blasts-plastic elements. The calculation results are also compared with measured values in the model test in order to check the applicability of the calculation equation for passive earth pressure thus obtained. Finally, this paper proposes a practicable calculation equation for passive earth pressure. 13 refs., 10 figs., 10 tabs.

  3. Ground Stabilization for foundation and excavation construction in Florida karst topography

    Science.gov (United States)

    Almaleh, L. J.; Grob, J. D.; Gorny, R. H.

    1993-12-01

    The construction of additional facilities at the Florida Power Corporation's Crystal River Energy Complex required an extensive stabilization program to construct foundations for approximately one half mile of cooling towers. This paper presents an overview of the techniques and methods used in the construction of additional facilities at the Crystal River Generating Station. Excavations for intake and discharge structures were to be more than 20 ft below the water table. Cooling tower foundations were constructed on extensively solutioned Florida limerock located on the central Gulf Coast of Florida. Hybrid ground modification techniques were used to stabilize soft or loose soils and solution features in the underlying limerock, allowing mat and spread footing foundations to be used for most of the facility. The ground modification techniques were used to detect, collapse, densify, and fill solution features below the structure foundations. The bearing capacity after ground modification was verified by field load tests. Subsurface investigations indicated that sheet pile excavations with grouted seals were the optimal technique for cofferdam excavations in the limerock formation. Existing collapsed caverns were encountered during construction of the cofferdam for the intake structure and the adjacent discharge structure, requiring a fast-track design change, considerable field coordination, and daily modifications to accommodate the varied conditions encountered. Tied-back soldier pile cofferdam construction was combined with grouting, underwater excavation, and a massive, unreinforced, concrete tremie slab with grouted anchors, and installed off a barge to provide a dewatered excavation. This project involved the use of hybrid soil-rock anchors to anchor one of the largest continuous placement tremie seals installed in Florida. Other excavations used sheeting and grouting of the underlying limerock formation to provide a dewatered excavation. Ground modification

  4. Bone x-ray

    Science.gov (United States)

    ... or broken bone Bone tumors Degenerative bone conditions Osteomyelitis (inflammation of the bone caused by an infection) ... Multiple myeloma Osgood-Schlatter disease Osteogenesis imperfecta Osteomalacia Osteomyelitis Paget disease of the bone Rickets X-ray ...

  5. 边坡侧面挖掘对建筑稳定性的影响——以重庆为例%Effect of Side Slope Excavation on Construction Stability-Taking Chongqing as an Example

    Institute of Scientific and Technical Information of China (English)

    黄治国

    2016-01-01

    Study in Chongqing mountain area construction side slope excavation of the effect on the stability of the building, to Chongqing slope safety design of the building to provide accurate basis. The current envelope with positive slope excavation construction earthquake-resistance design, does not take into account the effect of horizontal displacement difference, this will lead to the structure of the structure is not stable, safe hidden trouble. Put forward a kind of side slope mining in Chongqing mountain building based on the finite element method. According to the finite element analysis of stress on the construction side slope excavation model is set up, using the side slope excavation under the structure of the geometric equations, the structural equation and energy equation and the stiffness equation, the winning side slope excavation under the structure of the balance equation, the complete side slope excavation analysis of the stability of the building. The simulation experimental results show that the improved method can carry on the more precise to the slope stability of the building performance analysis, the effect is satisfactory.%研究重庆山区建筑中边坡侧面挖掘对建筑稳定性的影响,能够为重庆坡地建筑物的安全设计提供准确的依据.当前采用边坡正面挖掘进行建筑抗震性的包络设计,没有考虑横向位移差的作用,这样就会导致建筑物的结构不稳定,带来安全隐患.提出一种基于有限元的重庆山区建筑中边坡侧面挖掘的方法.根据有限元分析法建立边坡侧面挖掘下建筑的受力模型,利用边坡侧面挖掘下建筑物的几何方程、结构方程与势能方程求出单元刚度方程,最终获得边坡侧面挖掘下建筑物的平衡方程,完成边坡侧面挖掘对建筑稳定性的分析.仿真实验结果表明,改进方法能够对坡地建筑物的稳定性能进行更精确的分析,效果令人满意.

  6. [Bone disease in Gaucher's disease].

    Science.gov (United States)

    Roca Espiau, Mercedes

    2011-09-01

    The exposition aims, is to review the pathophysiological mechanisms of bone marrow involvement and the patterns of marrow infiltration by Gaucher cells. We have reviewed the different methods of assessment of bone marrow infiltration and its temporal development. Qualitative methods include simple radiography, magnetic resonance imaging (MRI), computed tomography (CT) and radioisotope. The simple radiography is the basic element, but its sensitivity is limited and only allows for assessing changes and trabecular bone remodeling MRI allows us to appreciate the bone marrow infiltration, detection of complications and response to therapy. Radioisotopes can contribute to the differential diagnosis of osteomyelitis and bone crises. Among the quantitative methods are the QCSI (quantitative chemical shift imaging) and the dual-energy X-ray absorptiometry (DEXA), as well as new quantitative techniques of CT, MRI and ultrasound densitometry. The QCSI performed an assessment of fat content of bone marrow in the spine. DEXA quantifies bone density by measuring the attenuation coefficient. The semiquantitative methods have various "scores" to establish criteria for generalized bone disease endpoints of disease progression and response to therapy.

  7. Regulation of insulin-like growth factor I transcription by cyclic adenosine 3',5'-monophosphate (cAMP) in fetal rat bone cells through an element within exon 1: protein kinase A-dependent control without a consensus AMP response element

    Science.gov (United States)

    McCarthy, T. L.; Thomas, M. J.; Centrella, M.; Rotwein, P.

    1995-01-01

    Insulin-like growth factor I (IGF-I) is a locally synthesized anabolic growth factor for bone. IGF-I synthesis by primary fetal rat osteoblasts (Ob) is stimulated by agents that increase the intracellular cAMP concentration, including prostaglandin E2 (PGE2). Previous studies with Ob cultures demonstrated that PGE2 enhanced IGF-I transcription through selective use of IGF-I promoter 1, with little effect on IGF-I messenger RNA half-life. Transient transfection of Ob cultures with an array of promoter 1-luciferase reporter fusion constructs has now allowed localization of a potential cis-acting promoter element(s) responsible for cAMP-stimulated gene expression to the 5'-untranslated region (5'-UTR) of IGF-I exon 1, within a segment lacking a consensus cAMP response element. Our evidence derives from three principal observations: 1) a transfection construct containing only 122 nucleotides (nt) of promoter 1 and 328 nt of the 5'-UTR retained full PGE2-stimulated reporter expression; 2) maximal PGE2-driven reporter expression required the presence of nt 196 to 328 of exon 1 when tested within the context of IGF-I promoter 1; 3) cotransfection of IGF-I promoter-luciferase-reporter constructs with a plasmid encoding the alpha-isoform of the catalytic subunit of murine cAMP-dependent protein kinase (PKA) produced results comparable to those seen with PGE2 treatment, whereas cotransfection with a plasmid encoding a mutant regulatory subunit of PKA that cannot bind cAMP blocked PGE2-induced reporter expression. Deoxyribonuclease I footprinting of the 5'-UTR of exon 1 demonstrated protected sequences at HS3A, HS3B, and HS3D, three of six DNA-protein binding sites previously characterized with rat liver nuclear extracts. Of these three regions, only the HS3D binding site is located within the functionally identified hormonally responsive segment of IGF-I exon 1. These results directly implicate PKA in the control of IGF-I gene transcription by PGE2 and identify a segment of

  8. Regulation of insulin-like growth factor I transcription by cyclic adenosine 3',5'-monophosphate (cAMP) in fetal rat bone cells through an element within exon 1: protein kinase A-dependent control without a consensus AMP response element

    Science.gov (United States)

    McCarthy, T. L.; Thomas, M. J.; Centrella, M.; Rotwein, P.

    1995-01-01

    Insulin-like growth factor I (IGF-I) is a locally synthesized anabolic growth factor for bone. IGF-I synthesis by primary fetal rat osteoblasts (Ob) is stimulated by agents that increase the intracellular cAMP concentration, including prostaglandin E2 (PGE2). Previous studies with Ob cultures demonstrated that PGE2 enhanced IGF-I transcription through selective use of IGF-I promoter 1, with little effect on IGF-I messenger RNA half-life. Transient transfection of Ob cultures with an array of promoter 1-luciferase reporter fusion constructs has now allowed localization of a potential cis-acting promoter element(s) responsible for cAMP-stimulated gene expression to the 5'-untranslated region (5'-UTR) of IGF-I exon 1, within a segment lacking a consensus cAMP response element. Our evidence derives from three principal observations: 1) a transfection construct containing only 122 nucleotides (nt) of promoter 1 and 328 nt of the 5'-UTR retained full PGE2-stimulated reporter expression; 2) maximal PGE2-driven reporter expression required the presence of nt 196 to 328 of exon 1 when tested within the context of IGF-I promoter 1; 3) cotransfection of IGF-I promoter-luciferase-reporter constructs with a plasmid encoding the alpha-isoform of the catalytic subunit of murine cAMP-dependent protein kinase (PKA) produced results comparable to those seen with PGE2 treatment, whereas cotransfection with a plasmid encoding a mutant regulatory subunit of PKA that cannot bind cAMP blocked PGE2-induced reporter expression. Deoxyribonuclease I footprinting of the 5'-UTR of exon 1 demonstrated protected sequences at HS3A, HS3B, and HS3D, three of six DNA-protein binding sites previously characterized with rat liver nuclear extracts. Of these three regions, only the HS3D binding site is located within the functionally identified hormonally responsive segment of IGF-I exon 1. These results directly implicate PKA in the control of IGF-I gene transcription by PGE2 and identify a segment of

  9. Bone pain

    DEFF Research Database (Denmark)

    Frost, Charlotte Ørsted; Hansen, Rikke Rie; Heegaard, Anne-Marie

    2016-01-01

    Skeletal conditions are common causes of chronic pain and there is an unmet medical need for improved treatment options. Bone pain is currently managed with disease modifying agents and/or analgesics depending on the condition. Disease modifying agents affect the underlying pathophysiology...... of the disease and reduce as a secondary effect bone pain. Antiresorptive and anabolic agents, such as bisphosphonates and intermittent parathyroid hormone (1-34), respectively, have proven effective as pain relieving agents. Cathepsin K inhibitors and anti-sclerostin antibodies hold, due to their disease...... modifying effects, promise of a pain relieving effect. NSAIDs and opioids are widely employed in the treatment of bone pain. However, recent preclinical findings demonstrating a unique neuronal innervation of bone tissue and sprouting of sensory nerve fibers open for new treatment possibilities....

  10. Bone graft

    Science.gov (United States)

    ... around the area. The bone graft can be held in place with pins, plates, or screws. Why ... Orthopaedic Surgery, San Francosco, CA. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the ...

  11. Spectroscopic analysis of bones for forensic studies

    Science.gov (United States)

    Tofanelli, Mirko; Pardini, Lorenzo; Borrini, Matteo; Bartoli, Fulvio; Bacci, Alessandra; D'Ulivo, Alessandro; Pitzalis, Emanuela; Mascherpa, Marco Carlo; Legnaioli, Stefano; Lorenzetti, Giulia; Pagnotta, Stefano; de Holanda Cavalcanti, Gildo; Lezzerini, Marco; Palleschi, Vincenzo

    2014-09-01

    The elemental analysis of human bones can give information about the dietary habits of the deceased, especially in the last years of their lives, which can be useful for forensic studies. The most important requirement that must be satisfied for this kind of analysis is that the concentrations of analyzed elements are the same as ante mortem. In this work, a set of bones was analyzed using Laser-Induced Breakdown Spectroscopy (LIBS) and validated using Inductively Coupled Plasma-Optical Emission Spectroscopy (ICP-OES), in order to compare those two techniques and to investigate the effect of possible alterations in the elemental concentrations' proportion resulting from the treatment usually applied for preparing the bones for traditional forensic analysis. The possibility that elemental concentrations' changes would occur after accidental or intentional burning of the bones was also studied.

  12. Spectroscopic analysis of bones for forensic studies

    Energy Technology Data Exchange (ETDEWEB)

    Tofanelli, Mirko [Applied and Laser Spectroscopy Laboratory, Institute of Chemistry of Organometallic Compounds, Research Area of CNR, Via G. Moruzzi, 1, 56124 Pisa (Italy); Pardini, Lorenzo [Institut für Physik und IRIS Adlershof, Humboldt-Universität zu Berlin, Zum Großen Windkanal 6, 12489 Berlin (Germany); Borrini, Matteo [Research Centre in Evolutionary Anthropology and Palaeoecology, School of Natural Sciences and Psychology, Liverpool John Moores University, Byrom Street, Liverpool (United Kingdom); Bartoli, Fulvio; Bacci, Alessandra [Department of Biology, University of Pisa, Via A. Volta, 4, 56126 Pisa (Italy); D’Ulivo, Alessandro; Pitzalis, Emanuela; Mascherpa, Marco Carlo; Legnaioli, Stefano; Lorenzetti, Giulia; Pagnotta, Stefano [Applied and Laser Spectroscopy Laboratory, Institute of Chemistry of Organometallic Compounds, Research Area of CNR, Via G. Moruzzi, 1, 56124 Pisa (Italy); Holanda Cavalcanti, Gildo de [Instituto de Fìsica, Universidade Federal Fluminense, Av. Gal. Milton Tavares de Souza, s/no Campus da Praia Vermelha, CEP 24210-346, Niterói, Rio de Janeiro (Brazil); Lezzerini, Marco [Department of Earth Sciences, University of Pisa, Via Santa Maria, 53, 56126 Pisa (Italy); Palleschi, Vincenzo, E-mail: vincenzo.palleschi@cnr.it [Applied and Laser Spectroscopy Laboratory, Institute of Chemistry of Organometallic Compounds, Research Area of CNR, Via G. Moruzzi, 1, 56124 Pisa (Italy)

    2014-09-01

    The elemental analysis of human bones can give information about the dietary habits of the deceased, especially in the last years of their lives, which can be useful for forensic studies. The most important requirement that must be satisfied for this kind of analysis is that the concentrations of analyzed elements are the same as ante mortem. In this work, a set of bones was analyzed using Laser-Induced Breakdown Spectroscopy (LIBS) and validated using Inductively Coupled Plasma–Optical Emission Spectroscopy (ICP-OES), in order to compare those two techniques and to investigate the effect of possible alterations in the elemental concentrations' proportion resulting from the treatment usually applied for preparing the bones for traditional forensic analysis. The possibility that elemental concentrations' changes would occur after accidental or intentional burning of the bones was also studied. - Highlights: • The LIBS analysis of (animal) bones is presented, to establish its feasibility for forensic studies. • Untreated bones and bones subjected to high temperatures (boiled, burned) were analyzed. • A simple calibration, using a single reference sample, gave reasonable quantitative results. • The comparison of the results demonstrates that LIBS analysis can provide nutritional information. • The nutritional information obtained are the same on untreated, boiled and burned bones.

  13. 3D Finite Element Simulation of Tunnel Boring Machine Construction Processes in Deep Water Conveyance Tunnel

    Institute of Scientific and Technical Information of China (English)

    ZHONG Denghua; TONG Dawei

    2009-01-01

    Applying stiffness migration method, a 3D finite element mechanical model is established to simulate the excavation and advance processes. By using 3D nonlinear finite element method, the tunnel boring machine (TBM) excavation process is dynamically simulated to analyze the stress and strain field status of surrounding rock and segment. The maximum tensile stress of segment ring caused by tunnel construction mainly lies in arch bottom and presents zonal distribution. The stress increases slightly and limitedly in the course of excavation. The maxi-mum and minimum displacements of segment, manifesting as zonal distribution, distribute in arch bottom and vault respectively. The displacements slightly increase with the advance of TBM and gradually tend to stability.

  14. Air Quality and Microclimatic Parameters During Excavation of Mala Kapela Tunnel

    Directory of Open Access Journals (Sweden)

    Mario Klanfar

    2015-06-01

    Full Text Available During excavation of the Mala Kapela tunnel, measurements of harmful gases concentration, ventilation parameters and microclimatic parameters were performed. Measurements were done in 17 occasions during period of 16 months, along the advance of the tunnel excavation. Consequently, large amount of data was obtained, in different tunnel chainages, ventilation ducts length, and in different work operations during the excavation. Main sources of harmful gases during tunnel excavation are explosives and diesel equipment. The concentration of the same mainly depends on explosive charge and overall diesel equipment power, present at the excavation face of the tunnel. Continuous measurements of the concentration of carbon monoxide (CO and dioxide (CO2, and nitrogen oxide (NO and dioxide (NO2 was performed during drilling, blasting, and loading and haulage operations. Measurements were done in 45 cases in total. Recorded data was analysed, where peak concentrations were joined to corresponding operation and the tunnel chainage. Regulations on threshold limit values were used to determine if concentrations rise above the permissible ones. In case they do, the time required for dilution of gases below permissible concentration was noted. Typically, concentrations of all measured gases rise rapidly after blasting. Afterwards, ventilation system acts to dilute them and maintain them relatively constant until the end of loading and haulage. According to measurements in this research, highest concentrations and longest time of dilution were found after blasting. At the same time, concentration of all measured gases exceeds permissible values. Carbon monoxide is found to exceed permissible values during all work operations. It shows most frequent transgression above the limit (in 33 to 100% of cases and highest time of dilution (up to 40 min. Air supply to the excavation face was measured in 25 cases. It was correlated to the length of ventilation ducts, as

  15. Organ printing: the future of bone regeneration?

    Science.gov (United States)

    Fedorovich, Natalja E; Alblas, Jacqueline; Hennink, Wim E; Oner, F Cumhur; Dhert, Wouter J A

    2011-12-01

    In engineered bone grafts, the combined actions of bone-forming cells, matrix and bioactive stimuli determine the eventual performance of the implant. The current notion is that well-built 3D constructs include the biological elements that recapitulate native bone tissue structure to achieve bone formation once implanted. The relatively new technology of organ/tissue printing now enables the accurate 3D organization of the components that are important for bone formation and also addresses issues, such as graft porosity and vascularization. Bone printing is seen as a great promise, because it combines rapid prototyping technology to produce a scaffold of the desired shape and internal structure with incorporation of multiple living cell types that can form the bone tissue once implanted.

  16. Ground Penetration Radar (GPR) Studies in Kureyşler Dam Rescue Excavations, Kütahya, Turkey

    Science.gov (United States)

    Mutlu, S.; Tün, M.; Pekkan, E.; Ecevitoğlu, B.; Guney, Y.

    2016-12-01

    Kureyşler Dam Rescue Excavations shows up as an important archaeological study implemented in Kütahya. It provides valuable data on and deepens our understanding of the Inner Western Anatolian region alongside Seyitömer and Çiledir Mound Excavations. The rescue excavations were started with the aim of determining the cultural artefacts that would be flooded by Kureyşler Irrigation Dam. Rescue excavations in archaeology, mostly called salvage archaeology, is archaeological survey and excavation applied in areas revealed by some constructions. These works must be undertaken in the shortest possible time, unlike traditional survey and excavation. Use of ground penetrating radar (GPR) allows field archaeologists to quickly discover and map buried archaeological features. This study describes the use of GPR during a rescue archaeology campaign at the Kureyşler Irrigation Dam, in Kütahya (Turkey). Closely spaced GPR transects were collected in a grid-based approach, covering three different areas from the site, using GSSI Sir 3000 System, with antennae frequency of 400MHz. Ground penetrating radar data were evaluated with a few commercial software. According to the interpretation of geophysical data, we suggested some excavation sites. The ancient ruins were found in the suggested area quite successful.

  17. A Top Pilot Tunnel Preconditioning Method for the Prevention of Extremely Intense Rockbursts in Deep Tunnels Excavated by TBMs

    Science.gov (United States)

    Zhang, Chuanqing; Feng, Xiating; Zhou, Hui; Qiu, Shili; Wu, Wenping

    2012-05-01

    The headrace tunnels at the Jinping II Hydropower Station cross the Jinping Mountain with a maximum overburden depth of 2,525 m, where 80% of the strata along the tunnels consist of marble. A number of extremely intense rockbursts occurred during the excavation of the auxiliary tunnels and the drainage tunnel. In particular, a tunnel boring machine (TBM) was destroyed by an extremely intense rockburst in a 7.2-m-diameter drainage tunnel. Two of the four subsequent 12.4-m-diameter headrace tunnels will be excavated with larger size TBMs, where a high risk of extremely intense rockbursts exists. Herein, a top pilot tunnel preconditioning method is proposed to minimize this risk, in which a drilling and blasting method is first recommended for the top pilot tunnel excavation and support, and then the TBM excavation of the main tunnel is conducted. In order to evaluate the mechanical effectiveness of this method, numerical simulation analyses using the failure approaching index, energy release rate, and excess shear stress indices are carried out. Its construction feasibility is discussed as well. Moreover, a microseismic monitoring technique is used in the experimental tunnel section for the real-time monitoring of the microseismic activities of the rock mass in TBM excavation and for assessing the effect of the top pilot tunnel excavation in reducing the risk of rockbursts. This method is applied to two tunnel sections prone to extremely intense rockbursts and leads to a reduction in the risk of rockbursts in TBM excavation.

  18. Effects of statistical distribution of joint trace length on the stability of tunnel excavated in jointed rock mass

    Directory of Open Access Journals (Sweden)

    Kayvan Ghorbani

    2015-12-01

    Full Text Available The rock masses in a construction site of underground cavern are generally not continuous, due to the presence of discontinuities, such as bedding, joints, faults, and fractures. The performance of an underground cavern is principally ruled by the mechanical behaviors of the discontinuities in the vicinity of the cavern. During underground excavation, many surrounding rock failures have close relationship with joints. The stability study on tunnel in jointed rock mass is of importance to rock engineering, especially tunneling and underground space development. In this study, using the probability density distribution functions of negative exponential, log-normal and normal, we investigated the effect of joint trace length on the stability parameters such as stress and displacement of tunnel constructed in rock mass using UDEC (Universal Distinct Element Code. It was obtained that normal distribution function of joint trace length is more critical on the stability of tunnel, and exponential distribution function has less effect on the tunnel stability compared to the two other distribution functions.

  19. Investigations of Ancient Terra-cotta Sarcophagi, Excavated in Enez (Ainos Turkey, by Instrumental Neutron Activation Analysis

    Directory of Open Access Journals (Sweden)

    Sevim Akyuz

    2015-12-01

    Full Text Available Ten terra-cotta sarcophagi, together with a terra-cotta aryballos (perfume jar, excavated in Su Terazisi necropolis of Enez-Turkey (Ancient Ainos, were investigated by Instrumental Neutron Activation Analysis (INAA, to determine the concentration of thirty two chemical elements: Na, K, Ca, Fe, Sc, Cr, Mn, Co, Ni, Cu, Zn, As, Se, Br, Rb, Sr, Sb, Cs, Ba, La, Ce, Nd, Sm, Eu, Tb, Dy, Yb, Lu, Hf, Ta, Th and U. The dataset was submitted to multivariate statistical analysis. The classification was done by cluster analysis. The results demonstrated the occurrence of two different groups of terra-cotta samples. Group I contains nine sarcophagi and terra-cotta aryballos whereas group II contains only one sample (E09-ST5-M26. High correlations between La and Ce (r2 = 0.92, and U and Th (r2 = 0.91 indicated that local clay was used for manufacturing the terra-cotta sarcophagi and aryballos but probably the claybed used for E09-ST5-M26 was different from that of others.

  20. Low Bone Density

    Science.gov (United States)

    ... Information › Bone Density Exam/Testing › Low Bone Density Low Bone Density Low bone density is when your ... compared to people with normal bone density. Detecting Low Bone Density A bone density test will determine ...

  1. A three-dimensional finite element analysis of a passive and friction fit implant abutment interface and the influence of occlusal table dimension on the stress distribution pattern on the implant and surrounding bone

    Directory of Open Access Journals (Sweden)

    Hasan Sarfaraz

    2015-01-01

    Conclusion : It can thus be concluded that the conical connection distributes more stress to the implant body and dissipates less stress to the surrounding bone. A narrow occlusal table considerably reduces the occlusal overload.

  2. 江苏宜兴市骆驼墩新石器时代遗址的发掘%Excavation on the Neolithic Luotuodun Site in Yixing City, Jiangsu

    Institute of Scientific and Technical Information of China (English)

    南京博物院考古研究所

    2003-01-01

    In November 2001-July 2002, the Institute of Archaeology, Nanjing Museum, carried out a large-scale excavation on the Luotuodun site in Yixing City, Jiangsu Province. They revealed a large number of tombs, ash-pits, house-foundations, shell deposits and sacrificial vestiges of the Majiabang culture and a few tombs and ash-pits of the Songze and Liangzhu cultures. The urn-burials of the Majiabang culture are the first discovered remains of this kind in the lower Changjiang River valley. The site yielded lots of stone implements, pottery vessels, bone artifacts, jade objects, animal bones and carbonized rice grains. The discoveries on the site made up a gap in our understanding of the prehistoric culture in the western Taihu Lake area and have great significance to the study of the Neolithic Age and civilizing course in the lower Changjiang River valley.

  3. Excavation at the Beiyangtai Site in the Fengfeng Mine, Handan City,Hebei%河北邯郸市峰峰矿区北羊台遗址发掘简报

    Institute of Scientific and Technical Information of China (English)

    河北省文物研究所; 邯郸市文物管理处; 峰峰矿区文物管理所

    2001-01-01

    In June-September 1996, the Hebei Provincial Institute of Cultural Relics and other units carried out a rescuing excavation at the Beiyangtai site, in an area of 2,478 sq m, which led to the discovery of predynastic and late Shang culture remains, including more than 200 cultural relics. In the predynastic Shang deposits, the remains include mainly round, oval, rectangular and irregular ash-pits;the objects are largely pottery, and stone tools, bone artifacts, oracle bones and shell articles occur in a smaller number. They belong to the Zhanghe type of predynastic Shang culture and go back roughly to the period directly prior to Cheng Tang conquering the Xia. As for late Shang cultural remains, there is only a shallow ditch with li tripod, dou stemmed vessel and other shards. Their date must not have been later than the Miaopu I period, i.e. corresponding to the Wu Ding reign.

  4. Bone strength and material properties of the glenoid

    DEFF Research Database (Denmark)

    Frich, Lars Henrik; Jensen, N.C.; Odgaard, A.;

    1997-01-01

    The quality of the glenoid bone is important to a successful total shoulder replacement. Finite element models have been used to model the response of the glenoid bone to an implanted prosthesis. Because very little is known about the bone strength and the material properties at the glenoid, thes...

  5. Bone marrow transplant

    Science.gov (United States)

    Transplant - bone marrow; Stem cell transplant; Hematopoietic stem cell transplant; Reduced intensity nonmyeloablative transplant; Mini transplant; Allogenic bone marrow transplant; Autologous bone marrow transplant; Umbilical ...

  6. Crucial problems on security assessment of a building site adjacent to an excavated high slope

    Institute of Scientific and Technical Information of China (English)

    文海家; ZHANG; Jialan; 等

    2002-01-01

    The subject of this work is the assessment on the stability of an excavated high slope in order to insure the security of the building site adjacent to the slope,which is frequently encountered in town construction in mountainous areas due to terrain limit.On the base of some typical engineering cases in Chongqing,several crucial problems on security assessment of building site adjacent to an excavated high slope,including the natural geological conditions and man-destroyed degree,engineering environment,potential failure pattern of the high slope,calculation parameters and analysis methods,are roundly discussed.It is demonstrated that the conclusion of security assessment can be determined according to the aspects above-mentioned,and the security assessment is one of the fundamental data to insure the safety of the related construction,site and buildings.

  7. Characterization studies of late Ottoman ceramics recovered from Istanbul Tekfur Palace excavation

    Energy Technology Data Exchange (ETDEWEB)

    Geckinli, A.E. [Istanbul Technical Univ. (Turkey). Chemistry and Metallurgical Engineering Faculty; Goektas, A.A.; Sueer, A. [Canakkale Ceramic Factory, Research and Development Lab., Can- Canakkale (Turkey); Yenisehirlioglu, F. [Hacettepe Univ., Dept. of History of Art, Beytepe-Ankara (Turkey)

    2002-07-01

    Tekfur Palace in Istanbul was used as a royal factory for ceramic and glass production between 1719- 1730. Excavation was started at Tekfur Palace in 1995 and lots of ceramic fragments including tiles, European porcelains and, various red and white body pottery were recovered. In addition to those sherds, raw and painting materials, frit and slag were also found. In this paper, the first report on the characterization of ten selected excavated underglaze decorated and also undecorated Tekfur tiles are given. The results compared with the 16. Century high quality Iznik tiles in order to investigate the reasons of the decline of quality in Ottoman ceramic technology during the 18{sup th} Century. (orig.)

  8. THRESHOLD CONDITION FOR CHOCKING IN OPEN CHANNELS AND EXCAVATION OF TAILRACE

    Institute of Scientific and Technical Information of China (English)

    NI Han-gen; LIU Ya-kun

    2005-01-01

    On the basis of energy and continuity equations a general threshold condition for chocking in open channels is obtained and a representation in terms of the Froude number at the upstream section and other parameters is given to predict whether the chocking phenomenon occurs or not at the downstream section.From the general threshold condition for chocking the limit contraction ratios of the channel width are introduced for both with and without the energy losses and a criterion for excavation of the tailrace to avoid chocking is derived.An example shows that using these criterion and the representation proposed for calculating flow depth it is very easy to determine the scheme of the excavation of the open channels.

  9. Preliminary report on the field surveys and excavations in the vicinity of Berettyóújfalu

    Directory of Open Access Journals (Sweden)

    András Füzesi

    2016-02-01

    Full Text Available The staff of the Institute of Archaeological Sciences at the Eötvös Loránd University carried out rescue excavationsprior to the construction of the M4 motorway in Hajdú-Bihar County in 2015. Within the frames of this project theopportunity was given to unearth approximately 5 hectares of a multi-period site east of the city of Berettyóújfalu.Before this excavation systematic field surveys had been carried out on the same site in a 24 hectares large area inthe frames of an OTKA (Hungarian Scientific Researh Fund project in 2013. Thus there is a possibility to compare thedata of the fieldwalking with the results of the excavation.

  10. Optimal Control for a Parallel Hybrid Hydraulic Excavator Using Particle Swarm Optimization

    Directory of Open Access Journals (Sweden)

    Dong-yun Wang

    2013-01-01

    Full Text Available Optimal control using particle swarm optimization (PSO is put forward in a parallel hybrid hydraulic excavator (PHHE. A power-train mathematical model of PHHE is illustrated along with the analysis of components’ parameters. Then, the optimal control problem is addressed, and PSO algorithm is introduced to deal with this nonlinear optimal problem which contains lots of inequality/equality constraints. Then, the comparisons between the optimal control and rule-based one are made, and the results show that hybrids with the optimal control would increase fuel economy. Although PSO algorithm is off-line optimization, still it would bring performance benchmark for PHHE and also help have a deep insight into hybrid excavators.

  11. Regolith Advanced Surface Systems Operations Robot (RASSOR) Phase 2 and Smart Autonomous Sand-Swimming Excavator

    Science.gov (United States)

    Sandy, Michael

    2015-01-01

    The Regolith Advanced Surface Systems Operations Robot (RASSOR) Phase 2 is an excavation robot for mining regolith on a planet like Mars. The robot is programmed using the Robotic Operating System (ROS) and it also uses a physical simulation program called Gazebo. This internship focused on various functions of the program in order to make it a more professional and efficient robot. During the internship another project called the Smart Autonomous Sand-Swimming Excavator was worked on. This is a robot that is designed to dig through sand and extract sample material. The intern worked on programming the Sand-Swimming robot, and designing the electrical system to power and control the robot.

  12. On the dissipation of negative excess porewater pressure induced by excavation in soft soil

    Institute of Scientific and Technical Information of China (English)

    LI Yu-qi; YING Hong-wei; XIE Kang-he

    2005-01-01

    Unloading induces negative excess porewater pressure in soil mass around a foundation pit during excavation. In this work, the dissipation rule of negative excess porewater pressure after excavation was studied. Analytical formulas for calculating the negative excess porewater pressures and the effective stresses were derived based on one-dimensional consolidation theory and Terzaghi's effective stress principle. The influence of the dissipation of negative excess porewater pressure on earth pressure inside and outside a foundation pit and the stability of the retaining structure were analyzed through a numerical example. It was indicated that the dissipation of negative excess porewater pressure is harmful to the stability of the retaining structure and that rapid construction can make full use of the negative porewater pressure.

  13. Reducing Environmental Impact of Aggregate Excavation in Small Tropic Pacific Islands

    Institute of Scientific and Technical Information of China (English)

    薛春汀

    2004-01-01

    Excavating sands and gravel on land in combination with constructing reservoirs for storing fresh water is an ideal approach in atolls. Appropriate mining of gravel from the prograding gravel beach is acceptable. Digging reef rock close to the edge of the wide ocean reef flat without surface loose sediments on it or sand beach can be accepted. Excavating sand from some depths in lagoon is a scientific approachparticularly important for urbanized atolls. However, selecting appropriate sites for mining sand other than at some depths in lagoon is suitable to rural islands without dense populations. These sites include up drift side of long groin on the reef fiat,partly filled access channel-port, outlet of artificial channel and lagoon margin on the prograding coast.

  14. To the Optimal Use of Technological Capabilities of the Excavator – Dragline in Construction

    Directory of Open Access Journals (Sweden)

    Khayrullin Rustam

    2016-01-01

    Full Text Available The mathematical model of motion of system “boom on a turning platform – bifilar suspended bucket” was created. As a control function, we choose the moment of force relatively non-movable base. The length of suspension of the bucket is assumed to be constant. The bucket of excavator is suspended bifilar. The bucket and the arrow needs to be moved from initial rest final rest position. The results of solution of the problem of rapid movement of bucket of excavator - dragline are presented. The structure of an optimal control law has been calculated by means of maximum Pontryagin’s principle and the method of control parameterization. A simple technique of calculations of optimal bucket trajectories has been developed. The dynamic of optimal control laws of the bucket and the arrow has been studied. Special software is created.

  15. Excavating silences and tensions of agency|passivity in science education reform

    Science.gov (United States)

    Rivera Maulucci, Maria S.

    2010-12-01

    I reflect on studies by Rodriguez and Carlone, Haun-Frank, and Kimmel to emphasize the ways in which they excavate silences in the science education literature related to linguistic and cultural diversity and situating the problem of reform in teachers rather than contextual factors, such as traditional schooling discourses and forces that serve to marginalize science. I propose that the current push for top-down reform and accountability diminishes opportunities for receptivity, learning with and from students in order to transform teachers' practices and promote equity in science education. I discuss tensions of agency and passivity in science education reform and argue that attention to authentic caring constitutes another silence in the science education literature. I conclude that the current policy context positions teachers and science education researchers as tempered radicals struggling against opp(reg)ressive reforms and that there is a need for more studies to excavate these and other silences.

  16. The Excavation of a Monastic Fishing Establishment at Oldstead Grange, North Yorkshire

    Directory of Open Access Journals (Sweden)

    Richard Kemp (with a pottery report by Wendy Sherlock

    1999-12-01

    Full Text Available Excavations directed by the writer in 1982-3 for the University of York Archaeological Society uncovered the foundations of a small structure on the shores of a fishpond that belonged to Byland Abbey in the 14th century. The site's location, combined with a number of associated lead net weights, suggest that it was connected with organised, large-scale, fish farming.

  17. Excavation and aggregation as organizing factors in de novo construction by mound-building termites.

    Science.gov (United States)

    Green, Ben; Bardunias, Paul; Turner, J Scott; Nagpal, Radhika; Werfel, Justin

    2017-06-14

    Termites construct complex mounds that are orders of magnitude larger than any individual and fulfil a variety of functional roles. Yet the processes through which these mounds are built, and by which the insects organize their efforts, remain poorly understood. The traditional understanding focuses on stigmergy, a form of indirect communication in which actions that change the environment provide cues that influence future work. Termite construction has long been thought to be organized via a putative 'cement pheromone': a chemical added to deposited soil that stimulates further deposition in the same area, thus creating a positive feedback loop whereby coherent structures are built up. To investigate the detailed mechanisms and behaviours through which termites self-organize the early stages of mound construction, we tracked the motion and behaviour of major workers from two Macrotermes species in experimental arenas. Rather than a construction process focused on accumulation of depositions, as models based on cement pheromone would suggest, our results indicated that the primary organizing mechanisms were based on excavation. Digging activity was focused on a small number of excavation sites, which in turn provided templates for soil deposition. This behaviour was mediated by a mechanism of aggregation, with termites being more likely to join in the work at an excavation site as the number of termites presently working at that site increased. Statistical analyses showed that this aggregation mechanism was a response to active digging, distinct from and unrelated to putative chemical cues that stimulate deposition. Agent-based simulations quantitatively supported the interpretation that the early stage of de novo construction is primarily organized by excavation and aggregation activity rather than by stigmergic deposition. © 2017 The Author(s).

  18. Structural responses of secondary lining of high-speed railway tunnel excavated in loess ground

    OpenAIRE

    Zhang, Dingli; Fang, Qian; Li, Pengfei; Wong, Louis

    2013-01-01

    To systematically study the mechanical properties and structural responses of the secondary lining for high-speed railway tunnels excavated in loess ground, on-site monitoring was performed to measure the contact pressure between the primary lining and secondary lining. It is found that the contact pressure reaches its first peak value when the tunnel formwork carriage is removed. The load acting on secondary lining is in the form of deformation pressure, which is different from the loose pre...

  19. Remediation of PCB contaminated soils in the Canadian Arctic: excavation and surface PRB technology.

    Science.gov (United States)

    Kalinovich, Indra; Rutter, Allison; Poland, John S; Cairns, Graham; Rowe, R Kerry

    2008-12-15

    The site BAF-5 is located on the summit of Resolution Island, Nunavut, just southeast of Baffin Island at 61 degrees 35'N and 60 degrees 40'W. The site was part of a North American military defense system established in the 1950s that became heavily contaminated with PCBs during and subsequent, its operational years. Remediation through excavation of the PCB contaminated soil at Resolution Island began in 1999 and at its completion in 2006 approximately 5 tonnes of pure PCBs in approximately 20,000 m3 of soil were remediated. Remediation strategies were based on both quantity of soil and level of contamination in the soil. Excavation removed 96% of the PCB contaminated soil on site. In 2003, a surface funnel-and-gate permeable reactive barrier was design and constructed to treat the remaining contamination left in rock crevices and inaccessible areas of the site. Excavation had destabilized contaminated soil in the area, enabling contaminant migration through erosion and runoff pathways. The barrier was designed to maximize sedimentation through settling ponds. This bulk removal enabled the treatment of highly contaminated fines and water through a permeable gate. The increased sediment loading during excavation required both modifications to the funnel and a shift to a more permeable, granular system. Granulated activated charcoal was chosen for its ability to both act as a particle retention filter and adsorptive filter. The reduction in mass of PCB and volume of soils trapped by the funnel of the barrier indicate that soils are re-stabilizing. In 2007, nonwoven geotextiles were re-introduced back into the filtration system as fine filtering could be achieved without clogging. Monitoring sites downstream indicate that the barrier system is effective. This paper describes the field progress of PCB remediation at Resolution Island.

  20. Numerical Analysis of Advanced Displacement in Construction Progress of Tunnel Excavation with Weak Surrounding Rock

    Directory of Open Access Journals (Sweden)

    Qian Zhang

    2013-07-01

    Full Text Available Analysis of advanced displacement in construction progress of tunnel excavation with weak surrounding rock is carried out by numerical method and comparison of model test result. In allusion to the problems of regional landslides and extruded large-deformation seriously impacting the stability of rock mass in construction process of large-section tunnel with weak surrounding rock, the elastic-plastic numerical simulation relying on Liangshui tunnel of Lan-Yu railroad is conducted on mechanical behaviors and deformation steric effect of tunnel construction and the calculation results are compared with the modeling data. The research results show that: the steric effect of excavation face is the dominant factor in the incidence of working face and the stress of surrounding rocks gradually releases from excavation face; the range of 0.5~1 times the cave diameter around rock mass in front of working face is the disturbance range and the key area of stabilization and reinforcement for wake surrounding rock. According to the analysis and construction practice, the supporting structure of large-section tunnel with weak surrounding rock should be established as soon as possible to control the displacement change of surrounding rock in the range of load-bearing ring, reduce disturbance and improve the self-bearing capability of surrounding rock. Because of the distinct excavation steric effect of weak surrounding rock, the secondary lining structure must be established in time to bear the later pressure and restrict the large displacement of surrounding rock. The research results can provide reliable basis for engineering stability control of analogous tunnels.