In-shoe plantar tri-axial stress profiles during maximum-effort cutting maneuvers.
Cong, Yan; Lam, Wing Kai; Cheung, Jason Tak-Man; Zhang, Ming
2014-12-18
Soft tissue injuries, such as anterior cruciate ligament rupture, ankle sprain and foot skin problems, frequently occur during cutting maneuvers. These injuries are often regarded as associated with abnormal joint torque and interfacial friction caused by excessive external and in-shoe shear forces. This study simultaneously investigated the dynamic in-shoe localized plantar pressure and shear stress during lateral shuffling and 45° sidestep cutting maneuvers. Tri-axial force transducers were affixed at the first and second metatarsal heads, lateral forefoot, and heel regions in the midsole of a basketball shoe. Seventeen basketball players executed both cutting maneuvers with maximum efforts. Lateral shuffling cutting had a larger mediolateral braking force than 45° sidestep cutting. This large braking force was concentrated at the first metatarsal head, as indicated by its maximum medial shear stress (312.2 ± 157.0 kPa). During propulsion phase, peak shear stress occurred at the second metatarsal head (271.3 ± 124.3 kPa). Compared with lateral shuffling cutting, 45° sidestep cutting produced larger peak propulsion shear stress (463.0 ± 272.6 kPa) but smaller peak braking shear stress (184.8 ± 181.7 kPa), of which both were found at the first metatarsal head. During both cutting maneuvers, maximum medial and posterior shear stress occurred at the first metatarsal head, whereas maximum pressure occurred at the second metatarsal head. The first and second metatarsal heads sustained relatively high pressure and shear stress and were expected to be susceptible to plantar tissue discomfort or injury. Due to different stress distribution, distinct pressure and shear cushioning mechanisms in basketball footwear might be considered over different foot regions.
Active axial stress in mouse aorta.
Agianniotis, A; Rachev, A; Stergiopulos, N
2012-07-26
The study verifies the development of active axial stress in the wall of mouse aorta over a range of physiological loads when the smooth muscle cells are stimulated to contract. The results obtained show that the active axial stress is virtually independent of the magnitude of pressure, but depends predominately on the longitudinal stretch ratio. The dependence is non-monotonic and is similar to the active stress-stretch dependence in the circumferential direction reported in the literature. The expression for the active axial stress fitted to the experimental data shows that the maximum active stress is developed at longitudinal stretch ratio 1.81, and 1.56 is the longitudinal stretch ratio below which the stimulation does not generate active stress. The study shows that the magnitude of active axial stress is smaller than the active circumferential stress. There is need for more experimental investigations on the active response of different types of arteries from different species and pathological conditions. The results of these studies can promote building of refined constrictive models in vascular rheology. Copyright © 2012 Elsevier Ltd. All rights reserved.
Axial residual stresses in boron fibers
Behrendt, D. R.
1978-01-01
A method of measuring axial residual stresses in boron fibers is presented. With this method, the axial residual stress distribution as a function of radius is determined from the fiber surface to the core including the average residual stress in the core. Such measurements on boron on tungsten (B/W) fibers show that the residual stresses for 102, 142, 203, and 366 micron diam fibers are similar, being compressive at the surface and changing monotonically to a region of tensile stress within the boron. At approximately 25% of the original radius, the stress reaches a maximum tensile stress of about 860 MN sq m and then decreases to a compressive stress near the tungsten boride core. Data are presented for 203-micron diam B/W fibers that show annealing above 900 C reduces the residual stresses. A comparison between 102-micron diam B/W and boron on carbon (B/C) show that the residual stresses are similar in the outer regions of the fibers, but that large differences near and in the core are observed. Fracture of boron fibers is discussed.
Kilburn-Toppin, Fleur; Arthurs, Owen J.; Tasker, Angela D.; Set, Patricia A.K. [Addenbrooke' s Hospital, Cambridge University Teaching Hospitals NHS Foundation Trust, Department of Radiology, Box 219, Cambridge (United Kingdom)
2013-07-15
Maximum intensity projection (MIP) images might be useful in helping to differentiate small pulmonary nodules from adjacent vessels on thoracic multidetector CT (MDCT). The aim was to evaluate the benefits of axial MIP images over axial source images for the paediatric chest in an interobserver variability study. We included 46 children with extra-pulmonary solid organ malignancy who had undergone thoracic MDCT. Three radiologists independently read 2-mm axial and 10-mm MIP image datasets, recording the number of nodules, size and location, overall time taken and confidence. There were 83 nodules (249 total reads among three readers) in 46 children (mean age 10.4 {+-} 4.98 years, range 0.3-15.9 years; 24 boys). Consensus read was used as the reference standard. Overall, three readers recorded significantly more nodules on MIP images (228 vs. 174; P < 0.05), improving sensitivity from 67% to 77.5% (P < 0.05) but with lower positive predictive value (96% vs. 85%, P < 0.005). MIP images took significantly less time to read (71.6 {+-} 43.7 s vs. 92.9 {+-} 48.7 s; P < 0.005) but did not improve confidence levels. Using 10-mm axial MIP images for nodule detection in the paediatric chest enhances diagnostic performance, improving sensitivity and reducing reading time when compared with conventional axial thin-slice images. Axial MIP and axial source images are complementary in thoracic nodule detection. (orig.)
49 CFR 230.24 - Maximum allowable stress.
2010-10-01
... 49 Transportation 4 2010-10-01 2010-10-01 false Maximum allowable stress. 230.24 Section 230.24... Allowable Stress § 230.24 Maximum allowable stress. (a) Maximum allowable stress value. The maximum allowable stress value on any component of a steam locomotive boiler shall not exceed 1/4 of the ultimate...
High-resolution axial MR imaging of tibial stress injuries
Mammoto Takeo
2012-05-01
Full Text Available Abstract Purpose To evaluate the relative involvement of tibial stress injuries using high-resolution axial MR imaging and the correlation with MR and radiographic images. Methods A total of 33 patients with exercise-induced tibial pain were evaluated. All patients underwent radiograph and high-resolution axial MR imaging. Radiographs were taken at initial presentation and 4 weeks later. High-resolution MR axial images were obtained using a microscopy surface coil with 60 × 60 mm field of view on a 1.5T MR unit. All images were evaluated for abnormal signals of the periosteum, cortex and bone marrow. Results Nineteen patients showed no periosteal reaction at initial and follow-up radiographs. MR imaging showed abnormal signals in the periosteal tissue and partially abnormal signals in the bone marrow. In 7 patients, periosteal reaction was not seen at initial radiograph, but was detected at follow-up radiograph. MR imaging showed abnormal signals in the periosteal tissue and entire bone marrow. Abnormal signals in the cortex were found in 6 patients. The remaining 7 showed periosteal reactions at initial radiograph. MR imaging showed abnormal signals in the periosteal tissue in 6 patients. Abnormal signals were seen in the partial and entire bone marrow in 4 and 3 patients, respectively. Conclusions Bone marrow abnormalities in high-resolution axial MR imaging were related to periosteal reactions at follow-up radiograph. Bone marrow abnormalities might predict later periosteal reactions, suggesting shin splints or stress fractures. High-resolution axial MR imaging is useful in early discrimination of tibial stress injuries.
Axial stress localization facilitates pressure propagation in gelled pipes
Norrman, Jens; Skjæraasen, Olaf; Oschmann, Hans-Jörg; Paso, Kristofer; Sjöblom, Johan
2016-03-01
Paraffin wax-oil gels are unique rheological fluids which undergo shear degradation starting at a deformation (shear strain level) of approximately 1%. Flow commencement in pipelines filled with wax-oil gels is a complex hydrodynamic process involving propagation of acoustic, diffusive, and rheological degradation pressure wave fronts. Dynamic simulation informed by qualified rheological relations provides useful insight into the physical nature of these flow processes. Eulerian simulations are presented which emulate known physical phenomena and essential characteristics of wax-gel flow dynamics. A constitutive rheological equation set accounts for deformation-driven reduction in yield stress and viscosity terms. No explicit time-dependent rheological parameters are utilized in the equations. Rheological yielding alters the nature of the dominant pressure wave from inherently diffusive towards self-sharpening. Axial stress localization effectively sequentializes the gel breakage process, quantified by reduced length of the pressure wave-front zone. Ultimately, axial stress localization allows flow in longer pipe segments, albeit with a concomitant time delay. Viscous behavior and yielding degradation behavior are shown to account for upward and downward concavity in transient axial pressure profiles, respectively. Overall, a unique synergy between gel compressibility and gel degradation is revealed. Deformation-coupled interaction between compressibility and degradation allows pressure propagation and subsequent sustained flow through a gel material which is otherwise immobile in the incompressible case.
The Effect of Axial Stress on YBCO Coils
Sampson, W.; Anerella, M.; Cozzolino, J.P.; Gupta, R.C.; Shiroyanagi, Y.; Evangelou, E.
2011-03-28
The large aspect ratio of typical YBCO conductors makes them ideal for constructing solenoids from pancake style coils. An advantage of this method is that each subunit can be tested before assembly into the finished magnet. The fact that conductors are available in relatively short lengths is another reason for using such a fabrication technique. The principal drawback is the large number of joints required to connect the coils together. When very high field solenoids such as those contemplated for the muon collider are built in this way the magnetic forces between pancakes can be very large. Extensive measurements have been made on the effect of stress on short lengths of conductor, but there is little or no data on the effect of intercoil loading. The experiment described in this paper was designed to test the ability of YBCO coils to withstand these forces. A spiral wound 'pancake' coil made from YBCO coated conductor has been stressed to a pressure of 100MPa in the axial direction at 77K. In this case axial refers to the coil so that the force is applied to the edge of the conductor. The effect on the critical current was small and completely reversible. Repeatedly cycling the pressure had no measureable permanent effect on the coil. The small current change observed exhibited a slight hysteretic behaviour during the loading cycle.
Alatawneh, Natheer; Rahman, Tanvir; Lowther, David A.; Chromik, Richard
2017-06-01
Electric machine cores are subjected to mechanical stresses due to manufacturing processes. These stresses include radial, circumferential and axial components that may have significant influences on the magnetic properties of the electrical steel and hence, on the output and efficiencies of electrical machines. Previously, most studies of iron losses due to mechanical stress have considered only radial and circumferential components. In this work, an improved toroidal tester has been designed and developed to measure the core losses and the magnetic properties of electrical steel under a compressive axial stress. The shape of the toroidal ring has been verified using 3D stress analysis. Also, 3D electromagnetic simulations show a uniform flux density distribution in the specimen with a variation of 0.03 T and a maximum average induction level of 1.5 T. The developed design has been prototyped, and measurements were carried out using a steel sample of grade 35WW300. Measurements show that applying small mechanical stresses normal to the sample thickness rises the delivered core losses, then the losses decrease continuously as the stress increases. However, the drop in core losses at high stresses does not go lower than the free-stress condition. Physical explanations for the observed trend of core losses as a function of stress are provided based on core loss separation to the hysteresis and eddy current loss components. The experimental results show that the effect of axial compressive stress on magnetic properties of electrical steel at high level of inductions becomes less pronounced.
Toward Improved Rotor-Only Axial Fans—Part II: Design Optimization for Maximum Efficiency
Sørensen, Dan Nørtoft; Thompson, M. C.; Sørensen, Jens Nørkær
2000-01-01
Numerical design optimization of the aerodynamic performance of axial fans is carried out, maximizing the efficiency in a designinterval of flow rates. Tip radius, number of blades, and angular velocity of the rotor are fixed, whereas the hub radius andspanwise distributions of chord length...
On some method of the space elevator maximum stress reduction
Ambartsumian S. A.
2007-03-01
Full Text Available The possibility of the realization and exploitation of the space elevator project is connected with a number of complicated problems. One of them are large elastic stresses arising in the space elevator ribbon body, which are considerably bigger that the limit of strength of modern materials. This note is devoted to the solution of problem of maximum stress reduction in the ribbon by the modification of the ribbon cross-section area.
Christopher Chukwutoo Ihueze
2017-01-01
Full Text Available This article employed the Hertz contact stress theory and the finite element method to evaluate the maximum contact pressure and the limit stresses of orange fruit under transportation and storage. The elastic properties of orange fruits subjected to axial and axial contact were measured such that elastic limit force, elastic modulus, Poisson’s ratio and bioyield stress were obtained as 18 N, 0.691 MPa, 0.367, 0.009 MPa for axial compression and for radial loading were 15.69 N, 0.645 MPa, 0.123, 0.010 MPa. The Hertz maximum contact pressure was estimated for axial and radial contacts as 0.036 MPa. The estimated limiting yield stress estimated as von Mises stresses for the induced surface stresses of the orange topologies varied from 0.005 MPa–0.03 MPa. Based on the distortion energy theory (DET the yield strength of orange fruit is recommended as 0.03 MPa while based on the maximum shear stress theory (MSST is 0.01 MPa for the design of orange transportation and storage system.
A review of creep analysis and design under multi-axial stress states
Yao, H.-T. [School of Mechanical and Power Engineering, East China University of Science and Technology, 130, Meilong Street, PO Box 402, Shanghai 200237 (China); Xuan Fuzhen [School of Mechanical and Power Engineering, East China University of Science and Technology, 130, Meilong Street, PO Box 402, Shanghai 200237 (China)], E-mail: fzxuan@ecust.edu.cn; Wang Zhengdong; Tu Shantung [School of Mechanical and Power Engineering, East China University of Science and Technology, 130, Meilong Street, PO Box 402, Shanghai 200237 (China)
2007-10-15
The existence of multi-axial states of stress cannot be avoided in elevated temperature components. It is essential to understand the associated failure mechanisms and to predict the lifetime in practice. Although metal creep has been studied for about 100 years, many problems are still unsolved, in particular for those involving multi-axial stresses. In this work, a state-of-the-art review of creep analysis and engineering design is carried out, with particular emphasis on the effect of multi-axial stresses. The existing theories and creep design approaches are grouped into three categories, i.e., the classical plastic theory (CPT) based approach, the cavity growth mechanism (CGM) based approach and the continuum damage mechanics (CDM) based approach. Following above arrangements, the constitutive equations and design criteria are addressed. In the end, challenges on the precise description of the multi-axial creep behavior and then improving the strength criteria in engineering design are presented.
Fatigue life prediction method for contact wire using maximum local stress
Kim, Yong Seok; Haochuang, Li; Seok, Chang Sung; Koo, Jae Mean [Sungkyunkwan University, Suwon (Korea, Republic of); Lee, Ki Won; Kwon, Sam Young; Cho, Yong Hyeon [Korea Railroad Research Institute, Uiwang (Korea, Republic of)
2015-01-15
Railway contact wires supplying electricity to trains are exposed to repeated mechanical strain and stress caused by their own weight and discontinuous contact with a pantograph during train operation. Since the speed of railway transportation has increased continuously, railway industries have recently reported a number of contact wire failures caused by mechanical fatigue fractures instead of normal wear, which has been a more common failure mechanism. To secure the safety and durability of contact wires in environments with increased train speeds, a bending fatigue test on contact wire has been performed. The test equipment is too complicated to evaluate the fatigue characteristics of contact wire. Thus, the axial tension fatigue test was performed for a standard specimen, and the bending fatigue life for the contact wire structure was then predicted using the maximum local stress occurring at the top of the contact wire. Lastly, the tested bending fatigue life of the structure was compared with the fatigue life predicted by the axial tension fatigue test for verification.
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TRANSIENT TORSIONAL WAVE IN FINITE HOLLOW CYLINDER WITH INITIAL AXIAL STRESS
Huiming Wang; Weiqiu Chen
2008-01-01
An analytical solution is obtained for transient torsional vibration of a finite hollow cylinder with initial axial stress. The cylinder is subjected to dynamic shearing stress at the internal surface and is fixed at the external surface. The basic equations are presented and the solution is obtained by means of Fourier series expansion technique and the separation of variables method.The effects of the initial stress on the natural frequencies and transient torsional responses are presented and discussed.
Parametric Equation of Stress Concentration Factor for Circular X-Joints Under Axial Loads
QU Shu-ying; ZHANG Guo-dong; ZHANG Bao-feng; WANG Xin-jian
2007-01-01
In engineering practice,tubular X-joints have been widely used in offshore structures.The fatigue failure of tubular X-joints in offshore engineering is mainly caused by axial tensile stress.In this study,the stress concentration factor distribution along the weld toe in the hot spot stress region for tubular X-joints subject to axial loads have been analyzed by use of finite element method.Through numerical analysis,it has been found that the peak stress concentration factor is located at the saddle position.Thereafter,80 models have been analyzed,and the effect of the geometric parameters of a tubular X-joint on the stress concentration factor has been investigated.Based on the experimental values of the numerical stress concentration factor,a parametric equation to calculate the stress concentration factor of tubular X-joints has been proposed.The accuracy of this equation has been verified against the requirement of the Fatigue Guidance Review Panel,and the proposed equation is found capable of producing reasonably accurate stress concentration factor values for tubular X-joints subject to axial loads.
Fatigue Failure Results for Multi-Axial versus Uniaxial Stress Screen Vibration Testing
Wayne E. Whiteman
2002-01-01
Full Text Available To date, the failure potential and prediction between simultaneous multi-axial versus sequentially applied uniaxial vibration stress screen testing has been the subject of great debate. In most applications, current vibration tests are done by sequentially applying uniaxial excitation to the test specimen along three orthogonal axes. The most common standards for testing military equipment are published in MIL-STD-810F and NAVMAT P-9492. Previous research had shown that uniaxial testing may be unrealistic and inadequate. This current research effort is a continuing effort to systematically investigate the differences between fatigue damage mechanisms and the effects of uniaxial versus tri-axial testing. This includes assessing the ability of the tri-axial method in predicting the formation of damage mechanisms, specifically looking at the effects of stress or fatigue failure. Multi-axial testing achieves the synergistic effect of exciting all modes simultaneously and induces a more realistic vibration stress loading condition. As such, it better approximates real-world operating conditions. This paper provides the latest results on the differences between multi-axial and uniaxial testing of a simple notched cantilever beam.
Xiang Luo
2016-07-01
Full Text Available Recently, Vernier permanent magnet (VPM machines, one special case of magnetic flux-modulated (MFM machines, benefiting from their compact, simple construction and low-speed/ high-torque characteristics, have been receiving increasing interest. In this paper, the Vernier structure is integrated with an axial-flux PM machine to obtain the magnetic gear effect and produce an improved torque density for direct-drive wind power generation application. Another advantage of the proposed machine is that the stator flux rotating speed can be relatively high when the shaft speed is low. With this benefit, sensorless control strategy can be easily implemented in a wide speed range. In this paper, an improved sliding mode observer (SMO is proposed to estimate the rotor position and the speed of the proposed machine. With the estimated shaft speeds, the maximum power point tracking (MPPT control strategy is applied to maximize the wind power extraction. The machine design and the sensorless MPPT control strategy are verified by finite element analysis and experimental verification.
Dynamic buckling of elastic-plastic cylindrical shells and axial stress waves
徐新生; 苏先樾; 王仁
1995-01-01
The mechanism for bifurcation of elastic-plastic buckling of the semi-infinite cylindrical shell under impacting axial loads is proposed based on the theory of stress wave. Numerical results on three kinds of end supports and step and impulse loads are given.
Nijhuis, A; Ilyin, Y; Abbas, W [Faculty of Science and Technology, Low Temperature Division, University of Twente, PO Box 217, 7500 AE Enschede (Netherlands)], E-mail: a.nijhuis@tnw.utwente.nl
2008-06-15
We have measured the critical current (I{sub c}) of a high current density Nb{sub 3}Sn strand subjected to spatial periodic bending, periodic contact stress and uniaxial strain. The strand is destined for the cable-in-conduit conductors (CICC) of the European dipole (EDIPO) 12.5 T superconducting magnet test facility. The spatial periodic bending was applied on the strand, using the bending wavelengths from 5 to 10 mm with a peak bending strain of 1.5%, a periodic contact stress with a periodicity of 4.7 mm and a stress level exceeding 250 MPa. For the uniaxial strain characterization, the voltage-current characteristics were measured with an applied axial strain from -0.9% to +0.3%, with a magnetic field from 6 to 14 T, temperature from 4.2 to 10 K and currents up to almost 900 A. In addition the axial stiffness was determined by a tensile axial stress-strain test. The characterization of the strand is essential for understanding the behaviour of the strand under mainly axial thermal stress variation during cool down and transverse electromagnetic forces during charging, which is essential for the design of the CICC for the dipole magnet. The strand appears to be fully reversible in the compressive regime during the axial strain testing, while in the tensile regime, the behaviour is already irreversibly degraded when reaching the maximum in the critical current versus strain characteristic. The degradation is accentuated by an immediate decrease of the n value by a factor of 2. The parameters for the improved deviatoric strain description are derived from the I{sub c} data, giving the accuracy of the scaling with a standard deviation of 4 A, which is by far within the expected deviation for the large scale strand production of such a high J{sub c} strand. The I{sub c} versus the applied bending strain follows the low resistivity limit, indicative of full interfilament current transfer, while a strong decrease is observed at a peak bending strain of {approx}0
The multi-axial material fatigue under the combined loading with mean stress in three dimensions
Fojtík F.
2009-12-01
Full Text Available This contribution describes the application of Fuxa's conjugated strength criterion on the experimental results under combined loading of specimens made from common construction steel 11523.0, melt T31052. The specimens were stepwise loaded by the torque amplitude, combination of torque amplitude and tension pre-stress, further by the amplitude of the torque in combination with inner overpressure and axial tension force. The last set of specimens was loaded by the torque amplitude in combination with inner and external overpressure and with axial tension force. To obtain the data required as the input values for the conjugated criterion the stress/strain analysis of the specimens by the finite element method in software ANSYS was performed. The experiments were performed on modified testing machine equipped by overpressure chamber.
Effect of temperature and pressure on stress of impeller in axial-centrifugal combined compressor
Xinqian Zheng
2016-06-01
Full Text Available Axial-centrifugal combined compressors are commonly used, and the stresses of their impeller are important and influenced by temperature and pressure. The effects of temperature and pressure on the stresses of the impeller with different inlet conditions are investigated. Conjugate heat transfer analysis and three-dimensional structural finite element analysis are used to get the stresses of the impeller. The effects of temperature and pressure are obtained by comparing the equivalent (Von-Mises stresses between cases taking and not taking them into account. From the result, the temperature effect is surprisingly large for low inlet temperature, reaching 57% of the total equivalent stress, and should be carefully considered. The effect strongly relates with the inlet conditions and the disk thermal boundary conditions. Thus, the later can’t be treated as adiabatic as usual. For certain inlet conditions, the stress of the impeller can be improved by adjusting the disk thermal boundary conditions. In addition, the temperature mainly affects the stress on the disk and the root of the blade. The pressure effect is small for low inlet temperature and can be sufficiently large for high inlet temperature. Furthermore, the pressure mainly influences the stress on the blade part and can reduce the stresses at the inducer of a negative-lean impeller.
dos Santos, Mateus Bertolini Fernandes; Bacchi, Atais; Consani, Rafael Leonardo Xediek; Correr-Sobrinho, Lourenço
2015-01-01
The aim of this study was to evaluate the axial tightening force applied by conventional and diamondlike carbon (DLC)-coated screws and to verify, through three-dimensional finite element analysis (FEA), the stress distribution caused by different framework materials and prosthetic screws in overdenture frameworks with different misfit levels. The axial tightening force applied by the screw was evaluated by means of a titanium matrix connected to a load cell. Conventional titanium or DLC-coated screws were tightened with a digital torque wrench, and the load values were recorded. The values were applied in an FEA to a bar-clip attachment system connected to two 4.0 × 11-mm external-hexagon titanium implants placed in an anterior edentulous arch. DLC-coated and conventional screws were modeled with their respective axial forces obtained on the experimental evaluation for three bar framework materials (titanium, nickel-chromium, and cobalt-chromium) and three levels of misfit (100, 150, and 200 μm). Von Mises stresses for prosthetic components and maximum principal stress and microstrains (maximum principal strains) for bone tissue were measured. The mean force applied by the conventional screw was 25.55 N (± 1.78); the prosthetic screw coated with a DLC layer applied a mean force of 31.44 N (± 2.11), a statistically significant difference. In the FEA, the DLC screw led to higher stresses on the framework; however, the prosthetic screw suffered lower stress. No influence of screw type was seen in the bone tissue. Titanium frameworks reduced the stress transmitted to the bone tissue and the bar framework but had no influence on the screws. Higher misfit values resulted in an increased stress/strain in bone tissue and bar framework, which was not the case for retention screws.
Buckling of un—stiffened cylindrical shell under non—uniform axial compressive stress
宋昌永
2002-01-01
This paper provides a review of recent research advances and trends in the area of stability of unstiffened circular cylindrical shells subjected to general non-uniform axial compressive stresses.Only the more important and interesting aspects of the research,judged from a personal viewpoint,are discussed.They can be crudely classified into four categories:(1) shells subjected to non-uniform loads;(2) shells on discrete supports;(3) shells with intended cutouts/holes;and (4) shells with non-uniform settlements.
Buckling of un-stiffened cylindrical shell under non-uniform axial conpressive stress
宋昌永
2002-01-01
This paper provides a review of recent research advances and trends in the area of stability of un-stiffened circular cylindrical shells subjected to general non-uniform axial compressive stresses. Only the more important and interesting aspects of the research, judged from a personal viewpoint, are discussed. They can be crudely classified into four categories: (1) shells subjected to non-uniform loads; (2) shells on discrete supports; (3) shells with intended cutouts/holes; and (4) shells with non-uniform settlements.
Permeability Changes of Coal Cores and Briquettes under Tri-Axial Stress Conditions
Wierzbicki, Mirosław; Konečný, Pavel; Kožušníková, Alena
2014-12-01
The paper is dealing with the permeability of coal in triaxial state of stress. The permeability of coal, besides coal's methane capacity, is the main parameter determining the quantity of methane inflow into underground excavations. The stress in a coal seam is one of the most important factors influencing coal permeability therefore the permeability measurements were performed in tri-axial state of stress. The hydrostatic three-axial state of stress was gradually increased from 5 MPa with steps of 5 MPa up to a maximum of 30 MPa. Nitrogen was applied as a gas medium in all experiments. The results of the permeability measurements of coal cores from the "Zofiówka" mine, Poland, and three mines from the Czech Republic are presented in this paper. As a "reference", permeability measurements were also taken for coal briquettes prepared from coal dust with defined porosity. It was confirmed that the decreasing porosity of coal briquettes affects the decreasing permeability. The advantage of experimentation on coal briquettes is its good repeatability. From the experimental results, an empirical relation between gas permeability and confining pressure has also been identified. The empirical relation for coal briquettes is in good correspondence with published results. However, for coal cores, the character of change differs. The influence of confining pressure has a different character and the decrease in permeability is stronger due to the increasing confining pressure Przepuszczalność węgla, oprócz pojemności sorpcyjnej względem metanu jest głównym parametrem określającym dopływ metanu do podziemnych wyrobiskach górniczych. W warunkach naturalnych wartość przepuszczalności jest ściśle związana ze stanem naprężenia w pokładzie węgla. W pracy przedstawiono wyniki pomiarów przepuszczalności wykonanych w trójosiowym stanie naprężenia. Hydrostatyczny trójosiowy stan naprężenia stopniowo zwiększano od 5 MPa do maksymalnie 30 MPa z krokiem
FINITE ELEMENT FOR STRESS-STRAIN STATE MODELING OF TWO-LAYERED AXIALLY SYMMETRIC SHELLS
K. S. Kurochka
2015-07-01
Full Text Available Subject of Research. Computation of composite material designs requires application of numerical methods. The finiteelement method usage is connected with surface approximation problems. Application of volumetric and laminar elements leads to systems with large sizes and a great amount of computation. The objective of this paper is to present an equivalent two-layer mathematical model for evaluation of displacements and stresses of cross-ply laminated cone shells subjected to uniformly distributed load. An axially symmetric element for shell problems is described. Method. Axially symmetric finite element is proposed to be applied in calculations with use of correlation for the inner work of each layer separately. It gives the possibility to take into account geometric and physical nonlinearities and non-uniformity in the layers of the shell. Discrete mathematical model is created on the base of the finite-element method with the use of possible motions principle and Kirchhoff–Love assumptions. Hermite element is chosen as a finite one. Cone shell deflection is considered as the quantity sought for. Main Results. One-layered and two-layered cone shells have been considered for proposed mathematical model verification with known analytical and numerical analytical solutions, respectively. The axial displacements of the two-layered cone are measured with an error not exceeding 5.4 % for the number of finite elements equal to 30. The proposed mathematical model requires fewer nodes to define the finite element meshing of the system and much less computation time. Thereby time for finding solution decreases considerably. Practical Relevance. Proposed model is applicable for computation of multilayered designs under axially symmetric loads: composite high-pressure bottles, cylinder shaped fiberglass pipes, reservoirs for explosives and flammable materials, oil and gas storage tanks.
Estimation of the Axial Stress in High-Tension Bolt by Acoustoelastic Method
Chun, Hae Hwa; Lee, Tae Hoon; Jhang, Kyung Young [Hanyang University, Seoul (Korea, Republic of); Kim, Noh Yu [Korea University of Technology and Education, Cheonan (Korea, Republic of)
2006-10-15
The evaluation of clamping condition has been regarded as the main issue in the safety-maintenance of the clamped high-tension bolts. For this, this paper proposes a method to estimate the axial stress by measuring the Tofu (Time-Of-Flight) of ultrasonic wave, which is based on the acetylsalicylate or the dependency of sound speed on the stress. In this method, however, the variation of sound speed within the range of stress induced under the field condition is very small, and thus the accuracy of the Tofu measurement is important. We adopted the phase detection method using tone-burst ultrasonic wave to measure the precise Tofu. In order to verify the usefulness of the proposed method experiments are carried out and the results were compared with the stress measured by the strain gage. The results show good agreement with each other, and from these we can conclude that the proposed method is highly useful fnr the evaluation of clamping condition in the clamped high-tension bolts
Ji Pei
2016-04-01
Full Text Available Axial-flow pump with a two-way passage has been widely employed in irrigation and drainage projects. Because of the shape of the two-way inlet passage, the impeller easily induces vibration due to unstable turbulent flow. This vibration results in structural cracks and even hinders the safe operation of the pump. Deformation and stress distributions in the impeller were calculated using two-way coupled fluid–structure interaction simulations, and a quantitative analysis of blade deformation and stress is carried out to determine the structure critical region. The results show that the values of deformation and stress significantly decrease with an increasing flow rate and a decreasing head, and the maximum total deformation can be found in the impeller rim, while the maximum equivalent stress can be obtained near the impeller hub. The total deformations in the blade rim decrease from blade leading edge to trailing edge, and the equivalent stress in the blade hub initially increases and then declines, and in the end, it rapidly increases from the blade outlet to inlet. These results reveal the deformation and stress in the impeller to ensure reliability and specific theoretical guidance for the structural optimization design of a pump device.
Maximum twin shear stress factor criterion for sliding mode fracture initiation
黎振兹; 李慧剑; 黎晓峰; 周洪彬; 郝圣旺
2002-01-01
Previous researches on the mixed mode fracture initiation criteria were mostly focused on opening mode fracture. In this study, the authors proposed a new criterion for mixed mode sliding fracture initiation, which is the maximum twin shear stress factor criterion. The authors studied a finite width plate with central slant crack, subject to a far-field uniform uniaxial tensile or compressive stress.
Elastic Plastic Stress Distributions in Weld-bonded Lap Joint under Axial Loading
Essam A. Al-Bahkali
2014-06-01
Full Text Available Weld-bonding process is increasingly used in many industries such like automobile and aerospace. It offers significant improvements of sheet metal joints in static, dynamic, corrosion, noise resistance, stiffness and impact toughness properties. A full understanding of this process, including the elastic-plastic stress distribution in the joint, is a must for joints design and automation of manufacturing. Also, the modelling and analysis of this process, though it is complex, proves to be of prime importance. Thus, in this study a systematic experimental and theoretical study employing Finite Element Analysis (FEA is conducted on the weld-bonded joint, fabricated from Austenitic Stainless steel (AISI 304 sheets of 1.00 mm thickness and Epoxy adhesive Araldite 2011, subjected to axial loading. Complete 3-D finite element models are developed to evaluate the normal, shear and triaxial Von Mises stresses distributions across the entire joint, in both the elastic and plastic regions. The, needed quantities and properties, for the FE modelling and analysis, of the base metals and the adhesive, such like the elastic-plastic properties, modulus of elasticity, fracture limit, the nugget and Heat Affected Zones (HAZ properties, etc., are obtained from the experiments. The stress distribution curves obtained are found to be consistent with those obtained from the FE models and in excellent agreement with the experimental and theoretical published data, particularly in the elastic region. Furthermore, the stress distribution curves obtained for the weld-bonded joint display the best uniform smooth distribution curves compared to those obtained for the spot and bonded joint cases. The stress concentration peaks at the edges of the weld-bonded region, are almost eliminated resulting in achieving the strongest joint.
Stress-In-Motion (SIM) system for capturing tri-axial tyre-road interaction in the contact patch
De Beer, Morris
2013-08-01
Full Text Available A unique measuring system for the quantification of tri-axial (3-D) tyre contact force (or stress) distributions was designed, developed and used in several studies since 1994. The uniqueness of the system is defined by a textured measuring surface...
Kosogor, Anna
2016-06-01
An influence of axial mechanical stress on the hysteresis of martensitic transformation and ordinary magnetostriction of ferromagnetic shape memory alloy has been described in the framework of a Landau-type theory of phase transitions. It has been shown that weak stress can noticeably reduce the hysteresis of martensitic transformation. Moreover, the anhysteretic deformation can be observed when the applied mechanical stress exceeds a critical stress value. The main theoretical results were compared with recent experimental data. It is argued that shape memory alloys with extremely low values of shear elastic modulus are the candidates for the experimental observation of large anhysteretic deformations.
G. Meneghetti
2014-10-01
Full Text Available The energy dissipated to the surroundings as heat in a unit volume of material per cycle, Q, was recently proposed by the authors as fatigue damage index and it was successfully applied to correlate fatigue data obtained by carrying out fully reversed stress- and strain-controlled fatigue tests on AISI 304L stainless steel plain and notched specimens. The use of the Q parameter to analyse the experimental results led to the definition of a scatter band having constant slope from the low- to the high-cycle fatigue regime. In this paper the energy approach is extended to analyse the influence of mean stress on the axial fatigue behaviour of unnotched cold drawn AISI 304L stainless steel bars. In view of this, stress controlled fatigue tests on plain specimens at different load ratios R (R=-1; R=0.1; R=0.5 were carried out. A new energy parameter is defined to account for the mean stress effect, which combines the specific heat loss Q and the relative temperature variation due to the thermoelastic effect corresponding to the achievement of the maximum stress level of the stress cycle. The new two-parameter approach was able to rationalise the mean stress effect observed experimentally. It is worth noting that the results found in the present contribution are meant to be specific for the material and testing condition investigated here.
Suhir, E.
2009-02-01
We consider a bi-material assembly with a 'piecewise-continuous' bonding layer. The layer is characterized by different elastic constants of its 'pieces' (segments) and is assumed to be thin. Young's moduli of all the 'pieces' of the bonding layer are significantly lower than the moduli of the adherend materials. In such a situation the coefficient of thermal expansion (CTE) of the bonding material need not be accounted for. Only the interfacial compliance of the bonding layer is important. This is indeed the case for the majority of electronic, opto-electronic or photonic assemblies. We consider the situation when the assembly is manufactured at an elevated temperature and is subsequently cooled down to a low (say, room) temperature. The objective of the analysis is to develop a simple, easy-to-use and physically meaningful analytical ('mathematical') predictive model for the evaluation of the interfacial shearing stresses that arise at the boundaries of the 'pieces' (segments) of the bonding layer and at the assembly edge. The basic equation is obtained for the thermally induced forces acting in the adherends' cross-sections that correspond to the boundaries between the dissimilar portions of the bonding layer. This equation has the form of the theorem of three (bending) moments in the theory of multi-span beams lying on separate simple supports and could therefore be called the 'theorem of three axial forces'. We show, as an illustration, how this equation could be employed to design a bi-material assembly with an inhomogeneous bonding layer and with low interfacial shearing stresses. Low shearing stresses will certainly result in lower peeling stresses as well. The numerical example is carried out for an assembly with a relatively high-modulus bonding material in its mid-portion (aimed primarily at providing good adhesion and, if necessary, good heat transfer as well) and a low-modulus material in its peripheral portions (aimed primarily at bringing down the
Incorporation of Mean/Maximum Stress Effects in the Multiaxial Racetrack Filter
Marco Antonio Meggiolaro
2016-10-01
Full Text Available This work extends the Multiaxial Racetrack Filter (MRF to incorporate mean or maximum stress effects, adopting a filter amplitude that depends on the current stress level along the stress or strain path. In this way, a small stress or strain amplitude event can be filtered out if associated with a non-damaging low mean or peak stress level, while another event with the very same amplitude can be preserved if happening under a more damaging high mean or peak stress level. The variable value of the filter amplitude must be calculated in real time, thus it cannot depend on the peak or mean stresses along a load event, because it would require cycle identification and as so information about future events. Instead, mean/maximum stress effects are modeled in the filter as a function of the current (instantaneous hydrostatic or normal stress along the multiaxial load path, respectively for invariantbased and critical-plane models. The MRF efficiency is evaluated from tension-torsion experiments in 316L stainless steel tubular specimens under non-proportional (NP load paths, showing it can robustly filter out nondamaging events even under multiaxial NP variable amplitude loading histories
Kim, K. M.; Smetana, P.
1990-03-01
Growth of large diameter Czochralski (CZ) silicon crystals require complete elimination of dislocations by means of Dash technique, where the seed diameter is reduced to a small size typically 3 mm in conjunction with increase in the pull rate. The maximum length of the large CZ silicon is estimated at the fracture stress limit of the seed neck diameter ( d). The maximum lengths for 200 and 300 mm CZ crystals amount to 197 and 87 cm, respectively, with d = 0.3 cm; the estimated maximum weight is 144 kg.
Ogawa, Akira; Anzou, Hideki; Yamamoto, So; Shimagaki, Mituru
2015-11-01
In order to control the maximum tangential velocity Vθm(m/s) of the turbulent rotational air flow and the collection efficiency ηc (%) using the fly ash of the mean diameter XR50=5.57 µm, two secondary jet nozzles were installed to the body of the axial flow cyclone dust collector with the body diameter D1=99mm. Then in order to estimate Vθm (m/s), the conservation theory of the angular momentum flux with Ogawa combined vortex model was applied. The comparisons of the estimated results of Vθm(m/s) with the measured results by the cylindrical Pitot-tube were shown in good agreement. And also the estimated collection efficiencies ηcth (%) basing upon the cut-size Xc (µm) which was calculated by using the estimated Vθ m(m/s) and also the particle size distribution R(Xp) were shown a little higher values than the experimental results due to the re-entrainment of the collected dust. The best method for adjustment of ηc (%) related to the contribution of the secondary jet flow is principally to apply the centrifugal effect Φc (1). Above stated results are described in detail.
Creep measurements confirm steady flow after stress maximum in extension of branched polymer melts
Javier Alvarez, Nicolas; Román Marín, José Manuel; Huang, Qian;
2013-01-01
We provide conclusive evidence of nonmonotonic mechanical behavior in the extension of long-chain branched polymer melts. While nonmonotonic behavior is known to occur for solids, for the case of polymeric melts, this phenomenon is in direct contrast with current theoretical models. We rule out...... the possibility of the overshoot being an experimental artifact by confirming the existence of steady flow after a maximum in the ratio of stress to strain rate versus strain under both constant stress and constant strain-rate kinematics. This observation indicates the omission of important physics from current...
Design of reinforced concrete walls casted in place for the maximum normal stress of compression
T. C. Braguim
Full Text Available It is important to evaluate which designing models are safe and appropriate to structural analysis of buildings constructed in Concrete Wall system. In this work it is evaluated, through comparison of maximum normal stress of compression, a simple numerical model, which represents the walls with frame elements, with another much more robust and refined, which represents the walls with shells elements. The designing of the normal stress of compression it is done for both cases, based on NBR 16055, to conclude if the wall thickness initially adopted, it is enough or not.
Optimal design of the gerotor (2-ellipses) for reducing maximum contact stress
Kwak, Hyo Seo; Li, Sheng Huan [Dept. of Mechanical Convergence Technology, Pusan National University, Busan (Korea, Republic of); Kim, Chul [School of Mechanical Design and Manufacturing, Busan Institute of Science and Technology, Busan (Korea, Republic of)
2016-12-15
The oil pump, which is used as lubricator of engines and auto transmission, supplies working oil to the rotating elements to prevent wear. The gerotor pump is used widely in the automobile industry. When wear occurs due to contact between an inner rotor and an outer rotor, the efficiency of the gerotor pump decreases rapidly, and elastic deformation from the contacts also causes vibration and noise. This paper reports the optimal design of a gerotor with a 2-ellipses combined lobe shape that reduces the maximum contact stress. An automatic program was developed to calculate Hertzian contact stress of the gerotor using the Matlab and the effect of the design parameter on the maximum contact stress was analyzed. In addition, the method of theoretical analysis for obtaining the contact stress was verified by performing the fluid-structural coupled analysis using the commercial software, Ansys, considering both the driving force of the inner rotor and the fluid pressure, which is generated by working oil.
A MIXED MODE FRACTURE CRITERION BASED ON THE MAXIMUM TANGENTIAL STRESS IN BRITTLE INCLUSION
Ji Changjiang; Li Zhonghua; Sun Jun
2005-01-01
A closed-form solution for predicting the tangential stress of an inclusion located in mixed mode Ⅰ and Ⅱ crack tip field was developed based on the Eshelby equivalent inclusion theory. Then a mixed mode fracture criterion, including the fracture direction and the critical load, was established based on the maximum tangential stress in the inclusion for brittle inclusioninduced fracture materials. The proposed fracture criterion is a function of the inclusion fracture stress, its size and volume fraction, as well as the elastic constants of the inclusion and the matrix material. The present criterion will reduce to the conventional one as the inclusion having the same elastic behavior as the matrix material. The proposed solutions are in good agreement with detailed finite element analysis and measurement.
Finite Element Analysis of the Maximum Stress at the Joints of the Transmission Tower
Itam, Zarina; Beddu, Salmia; Liyana Mohd Kamal, Nur; Bamashmos, Khaled H.
2016-03-01
Transmission towers are tall structures, usually a steel lattice tower, used to support an overhead power line. Usually, transmission towers are analyzed as frame-truss systems and the members are assumed to be pin-connected without explicitly considering the effects of joints on the tower behavior. In this research, an engineering example of joint will be analyzed with the consideration of the joint detailing to investigate how it will affect the tower analysis. A static analysis using STAAD Pro was conducted to indicate the joint with the maximum stress. This joint will then be explicitly analyzed in ANSYS using the Finite Element Method. Three approaches were used in the software which are the simple plate model, bonded contact with no bolts, and beam element bolts. Results from the joint analysis show that stress values increased with joint details consideration. This proves that joints and connections play an important role in the distribution of stress within the transmission tower.
On the impact of multi-axial stress states on trailing edge bondlines in wind turbine rotor blades
Noever Castelos, Pablo; Balzani, Claudio
2016-09-01
For a reliable design of wind turbine systems all of their components have to be designed to withstand the loads appearing in the turbine's lifetime. When performed in an integral manner this is called systems engineering, and is exceptionally important for components that have an impact on the entire wind turbine system, such as the rotor blade. Bondlines are crucial subcomponents of rotor blades, but they are not much recognized in the wind energy research community. However, a bondline failure can lead to the loss of a rotor blade, and potentially of the entire turbine, and is extraordinarily relevant to be treated with strong emphasis when designing a wind turbine. Modern wind turbine rotor blades with lengths of 80 m and more offer a degree of flexibility that has never been seen in wind energy technology before. Large deflections result in high strains in the adhesive connections, especially at the trailing edge. The latest edition of the DNV GL guideline from end of 2015 demands a three-dimensional stress analysis of bondlines, whereas before an isolated shear stress proof was sufficient. In order to quantify the lack of safety from older certification guidelines this paper studies the influence of multi-axial stress states on the ultimate and fatigue load resistance of trailing edge adhesive bonds. For this purpose, detailed finite element simulations of the IWES IWT-7.5-164 reference wind turbine blades are performed. Different yield criteria are evaluated for the prediction of failure and lifetime. The results show that the multi-axial stress state is governed by span-wise normal stresses. Those are evidently not captured in isolated shear stress proofs, yielding non-conservative estimates of lifetime and ultimate load resistance. This finding highlights the importance to include a three-dimensional stress state in the failure analysis of adhesive bonds in modern wind turbine rotor blades, and the necessity to perform a three-dimensional characterization
Interaction of fatigue and creep of GH33 under multi-axial stress at high temperature
无
2003-01-01
Low-cycle fatigue experiments of tension-compression, torsion and tension-torsion with holding time were performed.The interaction law of creep and fatigue under multiaxial stress at high temperature was investigated, and the micro-mechanism ofequilibrium diagrams was analyzed. A united equation of fatigue life under multiaxial stress was proposed.
Badescu, V.; Murariu, V.; Rotariu, O; Rezlescu, N.
1996-01-01
The theory of magnetic particles′ capture on a HGMF-axial magnetic filter cell with bounded flow field is presented. The equations of particle motion for both potential and laminar flow are obtained. By analytical solving of these equations, the trajectories of particles are established. The flow velocity of the fluid suspension for the case of potential flow is set equal with the velocity averaged across the tube section for the laminar flow. Thus, it is possible to make a comparison between...
Gonzalez, L.G. [Departamento de Electronica y Comunicaciones, Universidad de los Andes, nucleo la Hechicera, 5101 Merida (Venezuela); Figueres, E.; Garcera, G. [Grupo de Sistemas Electronicos Industriales, Universidad Politecnica de Valencia, Camino de vera s/n, 46022 Valencia (Spain); Carranza, O. [Escuela Superior de Computo, Instituto Politecnico Nacional, Av. Juan de Dios Batiz s/n, 07738 DF (Mexico)
2010-07-15
This paper presents an improved maximum-power-point tracking algorithm for wind-energy-conversion-systems. The proposed method significantly reduces the turbine mechanical stress with regard to conventional techniques, so that both the maintenance needs and the medium time between failures are expected to be improved. To achieve these objectives, a sensorless speed control loop receives its reference signal from a modified Perturb and Observe algorithm, in which the typical steps on the reference speed have been substituted by a fixed and well-defined slope ramp signal. As a result, it is achieved a soft dynamic response of both the torque and the speed of the wind turbine, so that the whole system suffers from a lower mechanical stress than with conventional P and O techniques. The proposed method has been applied to a wind turbine based on a permanent magnet synchronous generator operating at variable speed, which is connected to the distribution grid by means of a back to back converter. (author)
ON THE ORIGIN OF STRESS PEAK IN UNI-AXIAL STRETCHING OF AMORPHOUS POLYMERS
QIAN Renyuan; SHEN Jingshu
1997-01-01
Rubber of high molar mass, like cis-polybutadiene, shows a stress peak on the engineering stress-strain curve during stretching at room temperature. In this work cispolybutadiene samples were swollen in a poor solvent, CHCla/EtOH (1/1 v/v), for different times. It was found that both the initial modulus and the stress peak on stretching decreased in magnitude with increasing swelling time and the peak disappeared entirely after1 hour of swelling. On further swelling the initial modulus increased somewhat and a small stress peak re-appeared after swelling for 2 h. The disappearance of the stress peak after swelling is interpreted as the result of disruption of cohesional entanglements present in the initial rubber sample. The re-appearance of a small stress peak and the increase of modulus on further swelling are interpreted as being of the same nature as the phenomenon of anti-plasticization. It is the result of forming some new cohesional entanglements of larger binding energies through longer range chain segmental motions excited after the disruption of the previously existing cohesional entanglements in the rubber. Thus an understanding of the stress peak on stretching a high molar mass rubber and the phenomenon of anti-plasticization on molecular level has been put forward.
Lager, J. R.
1975-01-01
A cylindrical shell structure 3.66 m (144 in.) high by 4.57 m (180 in.) diameter was designed using a wide variety of materials and structural concepts to withstand design ultimate combined loading 1225.8 N/cm (700 lb/in.) axial compression and 245.2 N/cm (140 lb/in.) torsion. The overall cylinder geometry and design loading are representative of that expected on a high performance space tug vehicle. The relatively low design load level results in designs that use thin gage metals and fibrous-composite laminates. Fabrication and structural tests of small panels and components representative of many of the candidate designs served to demonstrate proposed fabrication techniques and to verify design and analysis methods. Three of the designs evaluated, honeycomb sandwich with aluminum faceskins, honeycomb sandwich with graphite/epoxy faceskins, and aluminum truss with fiber-glass meteoroid protection layers, were selected for further evaluation.
Li Xuejun; Qiu Weiliang; Yuan Yincai; Li Ping
2006-01-01
The relation between the maximum contact stress ratio and deflection angle is derived from Hertz contact theory when the deflection of rotary kiln supporting wheel happens. According to the analysis of practical example, the maximum contact stress ratio within the deflection range of rotary kiln supporting wheel is listed. The contact stress will increase largely when rotary kiln supporting wheel deflects with little angle,which probably will result in accidents correlating to safety. This will provide theory conference for the design,the operating condition analysis and adjusting of the rotary kiln.
Sung Woo Park
2015-03-01
Full Text Available The safety of a multi-span waler beam subjected simultaneously to a distributed load and deflections at its supports can be secured by limiting the maximum stress of the beam to a specific value to prevent the beam from reaching a limit state for failure or collapse. Despite the fact that the vast majority of accidents on construction sites occur at waler beams in retaining wall systems, no safety monitoring model that can consider deflections at the supports of the beam is available. In this paper, a maximum stress estimation model for a waler beam based on average strains measured from vibrating wire strain gauges (VWSGs, the most frequently used sensors in construction field, is presented. The model is derived by defining the relationship between the maximum stress and the average strains measured from VWSGs. In addition to the maximum stress, support reactions, deflections at supports, and the magnitudes of distributed loads for the beam structure can be identified by the estimation model using the average strains. Using simulation tests on two multi-span beams, the performance of the model is evaluated by estimating maximum stress, deflections at supports, support reactions, and the magnitudes of distributed loads.
THERMAL STRESS FIELD WHEN CRACK ARREST IN AN AXIAL SYMMETRY METAL DIE USING ELECTROMAGNETIC HEATING
无
2006-01-01
In order to solve the thermal stress field around crack tip in metal die when crack prevention using electromagnetic heating, a metal die with a half-embedded round crack was selected as the study object. The complex function method was used as a basis for the theoretical model of the space crack prevention in metal dies using electromagnetic heating. The crack arrest was accomplished by a pulse current discharge through the inner and outer. The theoretical analysis results show that the temperature around the crack tip rises instantly above the melting point of the metal. Small welded joints are formed at a small sphere near the crack tip inside the metal die by metal melting as a result of the heat concentration effect when the current pulse discharged. The thermal compressive stress field appears around the crack tip at the moment. The research results show that the crack prevention using electromagnetic heating can decrease the stress concentration and forms a compressive stress area around the crack tip, and also prevents the main crack from propagating further, and the goal of crack preventing can be reached.
Ehlers, R.
1986-01-01
For a linear-elastic cylinder with an axial through crack subject to internal pressure loading, stress intensity factors and crack opening areas were calculated by the finite element method. Wall thickness and crack length were varied for constant mean radius of the cylinder, thus varying the shell parameter lambda with 2.5
Shape transformations of soft matter governed by bi-axial stresses.
Thérien-Aubin, Héloïse; Moshe, Michael; Sharon, Eran; Kumacheva, Eugenia
2015-06-21
Rational design of the programmable soft matter requires understanding of the effect of a complex metric on shape transformations of thin non-Euclidean sheets. In the present work, we explored experimentally and using simulations how simultaneous or consecutive application of two orthogonal perturbations to thin patterned stimuli-responsive hydrogel sheets affects their three-dimensional shape transformations. The final shape of the sheet is governed by the metric, but not the order, in which the perturbations are applied to the system, and is determined by the competition of small-scale bidirectional stresses. In addition, a new, unexpected transition from a planar state to an equilibrium helical shape of the hydrogel sheet is observed via a mechanism that is yet to be explained.
Vasile Cojocaru
2016-12-01
Full Text Available Several methods can be used in the FEM studies to apply the loads on a plain bearing. The paper presents a comparative analysis of maximum stress obtained for three loading scenarios: resultant force applied on the shaft – bearing assembly, variable pressure with sinusoidal distribution applied on the bearing surface, variable pressure with parabolic distribution applied on the bearing surface.
Ándonios D. Tsolakis
2011-01-01
Full Text Available Problem statement: Main purpose of this study was to investigation toothed gear loading problems using the Finite Element Method. Approach: We used Niemann's equations to compare maximum bending stress which was developed at critical gear-tooth flank point during gear meshing, applied for three distinct spur-gear sizes, each having different teeth number, module and power rating. Results: The results emerging after the application of Niemann's equations were compared to the results derived by application of the Finite Element Method (FEM for the same gear-loading input data. Results are quite satisfactory, since von Mises' equivalent stresses calculated with FEM are of the same order with the results of classical analytical method. Conclusion: Judging from the emerging results, deviation of the two methods, analytical (Niemann's equations and computational (FEM, referring to maximum bending stress is fairly slight, independently of the applied geometrical and loading data of each gear.
Blackwood, R.L.
1980-05-15
There are now available sufficient data from in-situ, pre-mining stress measurements to allow a first attempt at predicting the maximum stress magnitudes likely to occur in a given mining context. The sub-horizontal (lateral) stress generally dominates the stress field, becoming critical to stope stability in many cases. For cut-and-fill mining in particular, where developed fill pressures are influenced by lateral displacement of pillars or stope backs, extraction maximization planning by mathematical modelling techniques demands the best available estimate of pre-mining stresses. While field measurements are still essential for this purpose, in the present paper it is suggested that the worst stress case can be predicted for preliminary design or feasibility study purposes. In the Eurpoean continent the vertical component of pre-mining stress may be estimated by adding 2 MPa to the pressure due to overburden weight. The maximum lateral stress likely to be encountered is about 57 MPa at depths of some 800m to 1000m below the surface.
Shao, Y. F.; Song, F.; Jiang, C. P.; Xu, X. H.; Wei, J. C.; Zhou, Z. L.
2016-02-01
We study the difference in the maximum stress on a cylinder surface σmax using the measured surface heat transfer coefficient hm instead of its average value ha during quenching. In the quenching temperatures of 200, 300, 400, 500, 600 and 800°C, the maximum surface stress σmmax calculated by hm is always smaller than σamax calculated by ha, except in the case of 800°C; while the time to reach σmax calculated by hm (fmmax) is always earlier than that by ha (famax). It is inconsistent with the traditional view that σmax increases with increasing Biot number and the time to reach σmax decreases with increasing Biot number. Other temperature-dependent properties also have a small effect on the trend of their mutual ratios with quenching temperatures. Such a difference between the two maximum surface stresses is caused by the dramatic variation of hm with temperature, which needs to be considered in engineering analysis.
Analysis of Maximum Shear Stress of Asphalt Pavement%沥青路面最大剪应力分析
陈光伟; 费国新; 陈荣生
2012-01-01
Factors and variation of the maximum shear stress of the typical semi-rigid asphalt pavement and bridge deck pavement in Jiangsu were calculated and analyzed using ABAQUS software. The maximum shear stress distribution was consistent with the semi-rigid asphalt pavement and bridge deck pavement and the maximum shear stress level was close under the level. The maximum shear stress showed a positive correlation with the verticaland horizontal vehicle loads and was significantly affected by the loads. The maximum shear stress decreased as the pavement thickness and modulus increase, and increased as the semi-rigid base thickness and modulus increase, but the increase value was small. Thereby these analysis above would provides an academic basis for solving the rutting problem.%采用ABAQUS软件对典型半刚性基层沥青路面及桥面铺装层中最大剪应力影响因素及变化规律进行了计算与分析。分析表明：半刚性基层沥青路面与水泥混凝土桥面铺装层最大剪应力分布与变化规律基本一致，在相同荷载条件作用下，最大剪应力水平亦接近；最大剪应力与车辆垂直荷载和水平荷载作用呈正比关系，最大剪应力受其影响显著；最大剪应力随着面层或铺装层厚度、模量的增加而相应地变小，随着半刚性基层厚度与模量的增加而变大。以上抗剪影响因素及变化规律的研究为解决车辙问题提供了一定的理论基础。
Witting, Nanna; Andersen, Linda K; Vissing, John
2016-01-01
musculature involvement in the majority of myopathies in which paraspinal musculature was examined. Even in diseases named after a certain pattern of non-axial muscle affection, such as facioscapulohumeral and limb girdle muscular dystrophies, affection of the axial musculature was often severe and early...
Feinberg, Rose K; Hu, JunMei; Weaver, Mark A; Fillingim, Roger B; Swor, Robert A; Peak, David A; Jones, Jeffrey S; Rathlev, Niels K; Lee, David C; Domeier, Robert M; Hendry, Phyllis L; Liberzon, Israel; McLean, Samuel A
2017-04-01
Posttraumatic stress disorder (PTSD) symptoms and pain after traumatic events such as motor vehicle collision (MVC) have been proposed to be mutually promoting. We performed a prospective multicenter study that enrolled 948 individuals who presented to the emergency department within 24 hours of MVC and were discharged home after evaluation. Follow-up evaluations were completed 6 weeks, 6 months, and 1 year after MVC. Path analysis results supported the hypothesis that axial pain after MVC consistently promotes the maintenance of hyperarousal and intrusive symptoms, from the early weeks after injury through 1 year. In addition, path analysis results supported the hypothesis that one or more PTSD symptom clusters had an influence on axial pain outcomes throughout the year after MVC, with hyperarousal symptoms most influencing axial pain persistence in the initial months after MVC. The influence of hyperarousal symptoms on pain persistence was only present among individuals with genetic vulnerability to stress-induced pain, suggesting specific mechanisms by which hyperarousal symptoms may lead to hyperalgesia and allodynia. Further studies are needed to better understand the specific mechanisms by which pain and PTSD symptoms enhance one another after trauma, and how such mechanisms vary among specific patient subgroups, to better inform the development of secondary preventive interventions.
Wijesekara, Waruna; Rosendahl, Lasse; Wu, NingYu;
Oxide thermoelectric materials are promising candidates for energy harvesting from mid to high temperature heat sources. In this work, the oxide thermoelectric materials and the final design of the high temperature thermoelectric module were developed. Also, prototypes of oxide thermoelectric...... generator were built for high temperature applications. This paper specifically discusses the thermoelectric module design and the prototype validations of the design. Here p type calcium cobalt oxide and n type aluminum doped ZnO were developed as the oxide thermoelectric materials. Hot side and cold side...... temperatures were used as 1100 K and 400 K respectively. Using analytical methods, the optimum thermoelement length and the thermoelements area ratio were explored in order to provide the maximum power output by the uni-couple and it is compared to methods reported in literature. Based on operating conditions...
Sung Woo Park; Byung Kwan Oh; Hyo Seon Park
2015-01-01
The safety of a multi-span waler beam subjected simultaneously to a distributed load and deflections at its supports can be secured by limiting the maximum stress of the beam to a specific value to prevent the beam from reaching a limit state for failure or collapse. Despite the fact that the vast majority of accidents on construction sites occur at waler beams in retaining wall systems, no safety monitoring model that can consider deflections at the supports of the beam is available. In this...
Hakoyama, Tomoyuki; Kuwabara, Toshihiko
2013-12-01
A servo-controlled tension-internal pressure testing machine with an optical 3D deformation analysis system (ARAMIS) was used to measure the multi-axial plastic deformation behavior of a high-strength steel sheet for a range of strain from initial yield to fracture. The testing machine is capable of applying arbitrary principal stress or strain paths to a tubular specimen using an electrical, closed-loop servo-control system for axial force and internal pressure. Tubular specimens with an inner diameter of 44.6 mm were fabricated from a high-strength steel sheet with a tensile strength of 590 MPa and a thickness of 1.2 mm by roller bending and laser welding. Several linear and non-linear stress paths in the first quadrant of the stress space were applied to the tubular specimens in order to measure the forming limit curve (FLC) and forming limit stress curve (FLSC) of the as-received test material, in addition to the contours of plastic work and the directions of plastic strain rates. The contours of plastic work and the directions of plastic strain rates measured for the linear stress path experiments were compared with those calculated using selected yield functions in order to identify the most appropriate yield function for the test material. Moreover, a Marciniak-Kuczyński type (M-K) forming limit analysis was performed using the most appropriate yield function. The calculated and measured FLC and FLSC were compared in order to validate the M-K approach. The path-dependence of the FLC and FLSC was also investigated.
Kosyna, G.; Krasmann, H. (Technische Univ. Braunschweig, Pfleiderer-Inst. fuer Stroemungsmaschinen (Germany))
1992-08-01
When installing blowers, it is not always possible to ensure an optimum fluidic afflux, which can thus produce a change in the operating behaviour compared with the design. Using as an example an axial blower blade with small hub ratio and high aerodynamic blade load, under simulated non-rotation symmetrical allflux conditions, it was possible to show that with the examined distrubance configuration no extreme worsening was produced with regard to the achievable pressure increases and efficiencies of the blower stage. (orig.).
吴志荣; 胡绪腾; 宋迎东
2013-01-01
工程中的大多构件承受着复杂的载荷形式,将单轴疲劳模型应用到多轴载荷情况已不能满足工程精度的要求,多轴载荷下的疲劳寿命计算日益引起人们的重视.基于临界平面的思想,结合Fatemi-Socie(FS)模型和Smith-Watson-Topper(SWT)参数各自的优点,提出一种新的多轴疲劳寿命预测模型.该模型以最大切应变幅与最大切应变幅平面上修正SWT参数的和作为多轴疲劳损伤控制参量,此参量可以同时考虑非比例附加循环硬化和平均应力对材料多轴疲劳寿命的影响,能同时适用于比例和非比例加载下的多轴疲劳问题.采用纯钛Ti、BT9钛合金、304不锈钢、S45C钢和1045HR钢5种材料多轴疲劳试验数据对提出的模型进行评估和验证,对几种材料比例和非比例加载下的多轴疲劳寿命预测结果大都分布在试验结果的2倍分散带之内,结果表明提出的多轴疲劳寿命模型具有较高的预测精度.%The most components of engineering structures are usually subjected to a complex loading. It is unable to meet the requirements of engineering precision if a uniaxial fatigue model is used under multi-axial loading. The calculation of fatigue life prediction under multiaxial loading causes people's attention more and more. A new multiaxial fatigue life prediction model is proposed based on the critical plane criteria. The model integrates the respective advantages of Fatemi-Socie(FS) model and Smith-Watson-Topper(SWT) parameter. The damage parameter in this model takes the sum of the maximum shear strain amplitude and the modified SWT parameter on the maximum shear strain amplitude plain. It can consider the effects of additional cyclic hardening due to non-proportional loading and mean stress on the multi-axial fatigue life of material. The proposed model can be applied to proportional and non-proportional loading. The model is evaluated by the multiaxial fatigue test data of pure titanium, BT9
Mills, Dean E; Johnson, Michael A; McPhilimey, Martin J; Williams, Neil C; Gonzalez, Javier T; Barnett, Yvonne A; Sharpe, Graham R
2014-04-15
The influence of oxidative stress, diaphragm fatigue, and inspiratory muscle training (IMT) on the cytokine response to maximum sustainable voluntary ventilation (MSVV) is unknown. Twelve healthy males were divided equally into an IMT or placebo (PLA) group, and before and after a 6-wk intervention they undertook, on separate days, 1 h of (1) passive rest and (2) MSVV, whereby participants undertook volitional hyperpnea at rest that mimicked the breathing and respiratory muscle recruitment patterns commensurate with heavy cycling exercise. Plasma cytokines remained unchanged during passive rest. There was a main effect of time (P ventilation and increases in plasma IL-6 concentration. In conclusion, increases in plasma IL-1β and IL-6 concentrations during MSVV were not due to diaphragm fatigue or DNA damage in PBMC. Increases in plasma IL-6 concentration during MSVV are attenuated following IMT, and the plasma IL-6 response is dependent upon the level of respiratory muscle work and minute ventilation.
Uni-axial compaction of a granular material
Morland, L. W.; Sawicki, A.; Milne, P. C.
1993-11-01
S HEARING OF GRANULAR materials causes rearrangement of the granular structure which induces irreversible volume decrease and shear strain, in addition to reversible strain. The model adopted describes the reversible compression and shear by hypoelastic laws, and the irreversible compaction and shear by evolutionary laws. The latter are differential relations defining the progress of irreversible strain as an appropriate time-independent monotonie loading parameter increases, which incorporate dependence on the current state, and which prescribe a direction for the irreversible shear strain increment. The model is described by four material functions and two material constants, and has been shown to determine valid initial response to applied shear stress. We apply the model to the compaction of a granular material in uni-axial strain, which is described by two simultaneous differential equations for the axial stress and compaction with the axial strain as independent variable, together with algebraic relations for the pressure and lateral stress. The equation forms for loading-increasing axial stress—and unloading—decreasing axial stress-are distinct. Reformulation as differential equations for the pressure and the principal stress difference shows that the pressure derivative depends only on two of the material functions and one constant. The axial strain and lateral stress measured during a complete load-unload cycle on a sand determine the pressure and stress difference derivatives which are correlated directly with the model differential relations. Two material functions and one constant are determined by an optimization procedure from the complete loadunload ressure data, then the remaining two functions and constant from the stress difference data. Solution of the resulting model differential equations reproduces accurately the axial strain and lateral stress variations during the experimental loading cycle. In addition, model predictions for load
V. M. Prokhorenko
2013-10-01
Full Text Available The paper proposes a variant for solving the problem of reduction of longitudinal residual stresses in near-root region of a circumferential welded joint of section of steam pipeline by FEM simulation of the stress-strain state of repaired section of a circumferential weld in the zone of lack of root penetration on a thin-wall shell of 89 mm diameter and 6 mm wall thickness from steel 20. The result of solving the problem is total distribution of stresses and residual plastic deformations in the repaired zone.
Investigation of Aluminum-Copper Tube Hydroforming with Axial Feeding
Parto D., M.; Seyedkashi, S. M. H.; Liaghat, Gh.; Naeini, H. Moslemi; Panahizadeh R., V.
2011-01-01
Hydroforming of a two-layered Aluminum-Copper tube is investigated numerically and experimentally. Pressure is applied through a nonlinear path along with symmetrical axial feeding. ABAQUS/Explicit commercial code is used for finite element simulation of the process. ASTM C11000 Copper alloy is used as inner layer and ASTM AA1050A Aluminum alloy is used as outer layer. The simulation results show that the part can be successfully formed under internal pressure of 40 MPa with 8 mm axial displacement. Stress distributions on both inner and outer tubes are compared and maximum thinning on their wall is also discussed. Different friction conditions are applied on the process using different coefficients of friction and their effects are investigated on thinning percentage of inner and outer tubes and also on axial feeding. It is observed that finite element results are in good agreement with experimental results.
Mean stress effect under Multi-Axial High Cycle Fatigue loading for cast A356-T6 alloy
Houria M. Iben
2014-06-01
The obtained results show clearly that: (i the mean stress has detrimental, it is more significant in tension, lesser in tension-torsion case and slightly in torsion tests. (ii The improved DSG criterion describes very well the trend of the fatigue limit as a function of defect size and SDAS.
Salces Judit
2011-08-01
Full Text Available Abstract Background Reference genes with stable expression are required to normalize expression differences of target genes in qPCR experiments. Several procedures and companion software have been proposed to find the most stable genes. Model based procedures are attractive because they provide a solid statistical framework. NormFinder, a widely used software, uses a model based method. The pairwise comparison procedure implemented in GeNorm is a simpler procedure but one of the most extensively used. In the present work a statistical approach based in Maximum Likelihood estimation under mixed models was tested and compared with NormFinder and geNorm softwares. Sixteen candidate genes were tested in whole blood samples from control and heat stressed sheep. Results A model including gene and treatment as fixed effects, sample (animal, gene by treatment, gene by sample and treatment by sample interactions as random effects with heteroskedastic residual variance in gene by treatment levels was selected using goodness of fit and predictive ability criteria among a variety of models. Mean Square Error obtained under the selected model was used as indicator of gene expression stability. Genes top and bottom ranked by the three approaches were similar; however, notable differences for the best pair of genes selected for each method and the remaining genes of the rankings were shown. Differences among the expression values of normalized targets for each statistical approach were also found. Conclusions Optimal statistical properties of Maximum Likelihood estimation joined to mixed model flexibility allow for more accurate estimation of expression stability of genes under many different situations. Accurate selection of reference genes has a direct impact over the normalized expression values of a given target gene. This may be critical when the aim of the study is to compare expression rate differences among samples under different environmental
Hartl Christoph
2015-01-01
Full Text Available Feasible product geometries manufactured with micro-hydroforming, as well as process stability are crucially influenced by the microstructure of the used tube material. The higher ratio of grain size to tube wall thickness dk/t0 in micro-hydroforming, compared to conventional tube hydroforming, leads to an increase of scattering of process parameters and instabilities. This paper presents experimental and theoretical results for the micro-hydroforming of tubes made from stainless steel and from platinum with a focus on the correlations between the microstructure of the workpiece material, the stress state during forming and the resulting stability of the forming process. Investigated tube dimensions were 800 µm outer diameter and 40 µm wall thickness of the steel tubes, respectively 1650 µm and 76 µm of the platinum tubes. The average ratio dk/t0 was about 0.3 for the steel material and about 0.9 for the platinum alloy. It has been shown that superimposed axial stresses are suitable to reduce the restricting influence of an increased ratio dk/t0 and to improve the forming result as well as the process stability.
Warltier David C
2005-10-01
Full Text Available Abstract Introduction The success of vascular stents in the restoration of blood flow is limited by restenosis. Recent data generated from computational fluid dynamics (CFD models suggest that the vascular geometry created by an implanted stent causes local alterations in wall shear stress (WSS that are associated with neointimal hyperplasia (NH. Foreshortening is a potential limitation of stent design that may affect stent performance and the rate of restenosis. The angle created between axially aligned stent struts and the principal direction of blood flow varies with the degree to which the stent foreshortens after implantation. Methods In the current investigation, we tested the hypothesis that stent foreshortening adversely influences the distribution of WSS and WSS gradients using time-dependent 3D CFD simulations of normal arteries based on canine coronary artery measurements of diameter and blood flow. WSS and WSS gradients were calculated using conventional techniques in ideal (16 mm and progressively foreshortened (14 and 12 mm stented computational vessels. Results Stent foreshortening increased the intrastrut area of the luminal surface exposed to low WSS and elevated spatial WSS gradients. Progressive degrees of stent foreshortening were also associated with strut misalignment relative to the direction of blood flow as indicated by analysis of near-wall velocity vectors. Conclusion The current results suggest that foreshortening may predispose the stented vessel to a higher risk of neointimal hyperplasia.
Liu, Wei; Lu, Jian; Leung, Lai-Yung R.; Xie, Shang-Ping; Liu, Zhengyu; Zhu, Jiang
2015-02-22
This paper investigates the changes of the Southern Westerly Winds (SWW) and Southern Ocean (SO) upwelling between the Last Glacial Maximum (LGM) and preindustrial (PI) in the PMIP3/CMIP5 simulations, highlighting the role of the Antarctic sea ice in modulating the wind stress effect on the ocean. Particularly, a discrepancy may occur between the changes in SWW and westerly wind stress, caused primarily by an equatorward expansion of winter Antarctic sea ice that undermines the wind stress in driving the liquid ocean. Such discrepancy may reflect the LGM condition in reality, in view of that the model simulates this condition has most credible simulation of modern SWW and Antarctic sea ice. The effect of wind stress on the SO upwelling is further explored via the wind-induced Ekman pumping, which is reduced under the LGM condition in all models, in part by the sea-ice “capping” effect present in the models.
孙宗颀
2001-01-01
When a crack is subjected to shear force, crack branching usually occurs. Theoretical study shows that the crack branching under shear loading is caused by tensile stress, but not caused by shear fracture. The co-plane shear fracture could be obtained if compressive stress with given direction is applied to the specimen, subsequently, calculated shear fracture toughness, KⅡ C, is larger than KⅠ C. A prerequisite of possible occurrence of mode Ⅱ fracture was proposed. The study of shear fracture shows that the maximum circumferential stress theory considered its criterion as a parametric equation of a curve in KⅠ, KⅡ plane is incorrect; the predicted ratio KⅡ C/KⅠ C=0.866 is incorrect too.
Experimental and Numerical Investigation of an Axial Rotary Blood Pump.
Schüle, Chan Yong; Thamsen, Bente; Blümel, Bastian; Lommel, Michael; Karakaya, Tamer; Paschereit, Christian Oliver; Affeld, Klaus; Kertzscher, Ulrich
2016-04-18
Left ventricular assist devices (LVADs) have become a standard therapy for patients with severe heart failure. As low blood trauma in LVADs is important for a good clinical outcome, the assessment of the fluid loads inside the pump is critical. More specifically, the flow features on the surfaces where the interaction between blood and artificial material happens is of great importance. Therefore, experimental data for the near-wall flows in an axial rotary blood pump were collected and directly compared to computational fluid dynamic results. For this, the flow fields based on unsteady Reynolds-averaged Navier-Stokes simulations-computational fluid dynamics (URANS-CFD) of an axial rotary blood pump were calculated and compared with experimental flow data at one typical state of operation in an enlarged model of the pump. The focus was set on the assessment of wall shear stresses (WSS) at the housing wall and rotor gap region by means of the wall-particle image velocimetry technique, and the visualization of near-wall flow structures on the inner pump surfaces by a paint erosion method. Additionally, maximum WSS and tip leakage volume flows were measured for 13 different states of operation. Good agreement between CFD and experimental data was found, which includes the location, magnitude, and direction of the maximum and minimum WSS and the presence of recirculation zones on the pump stators. The maximum WSS increased linearly with pressure head. They occurred at the upstream third of the impeller blades and exceeded the critical values with respect to hemolysis. Regions of very high shear stresses and recirculation zones could be identified and were in good agreement with simulations. URANS-CFD, which is often used for pump performance and blood damage prediction, seems to be, therefore, a valid tool for the assessment of flow fields in axial rotary blood pumps. The magnitude of maximum WSS could be confirmed and were in the order of several hundred Pascal.
Chen, Kan; Liu, Xiang; Matsuki, Takayuki
2015-01-01
Inspired by the abundant experimental observation of axial vector states, we study whether the observed axial vector states can be categorized into the conventional axial vector meson family. In this paper we carry out analysis based on the mass spectra and two-body Okubo-Zweig-Iizuka-allowed decays. Besides testing the possible axial vector meson assignments, we also predict abundant information for their decays and the properties of some missing axial vector mesons, which are valuable to further experimental exploration of the observed and predicted axial vector mesons.
Numerical study on air-structure coupling dynamic characteristics of the axial fan blade
Chen, Q. G.; Xie, B.; Li, F.; Gu, W. G.
2013-12-01
In order to understand the dynamic characteristics of the axial-flow fan blade due to the effect of rotating stress and the action of unsteady aerodynamic forces caused by the airflow, a numerical simulation method for air-structure coupling in an axial-flow fan with fixed rear guide blades was performed. The dynamic characteristics of an axial-flow fan rotating blade were studied by using the two-way air-structure coupling method. Based on the standard k-ε turbulence model, and using weak coupling method, the preceding six orders modal parameters of the rotating blade were obtained, and the distributions of stress and strain on the rotating blade were presented. The results show that the modal frequency from the first to the sixth order is 3Hz higher than the modal frequency without considering air-structure coupling interaction; the maximum stress and the maximum strain are all occurred in the vicinity of root area of the blade no matter the air-structure coupling is considered or not, thus, the blade root is the dangerous location subjected to fatigue break; the position of maximum deformation is at the blade tip, so the vibration of the blade tip is significant. This study can provide theoretical references for the further study on the strength analysis and mechanical optimal design.
Lee, H.; Haimson, B.
2007-12-01
drillhole wall conditions is drastically different from that conventionally expected, but is compatible with breakout formation mechanism in granite (Haimson, Int. J. Rock Mech., 2007). All the 'unjacketed' true triaxial strength data can be fitted by a simple function in the octahedral shear stress versus octahedral normal stress domain, yielding a Nadai-type true triaxial strength criterion. The criterion can be used in conjunction with breakouts that have been located within the cored zone to yield the maximum horizontal in situ stress σH when the other two principal stress are known. Assuming that the state of stress at breakout-drillhole intersections (located for example by BHTV logging) is sufficient to bring about brittle failure (Vernik and Zoback, 1992), one can substitute the known principal stresses there (obtained from the Kirsch solution) for the corresponding values in the criterion. The in situ σv is given by the overburden density, σh is typically obtained from hydrofrac shut-in pressures, breakout width is extracted from BHTV logs, borehole fluid pressure is a function of its density, and the Poisson's ratio is obtained from mechanical lab testing. The only unknown, σH, is thus readily computed. An actual computation was not carried out because data on hydrofrac pressures and breakout dimensions were not available at the time of this submission.
王海; 穆康; 陈荣淋; 戚志博; 俞缙
2012-01-01
Concrete-cored sand-gravel pile is a new and typical composite material pile. Theoretical a-nalysis of core pile axial stress are carried out based on Mindlin displacement solution in elastic semi-infinite body and composite material mechanics. Regularities of distribution of core pile axial stress under different axial loads, grade of concret and elastic modulus of sandy soil are deduced, theoretical results are compared with field test results. The comparison results show that theoretical analysis results are accordant with field test results and they can be verified each other. Theoretical study has significant value for analysis of performance mechanism of concrete-cored sand-gravel pile.%劲性砂桩是一种新型复合材料桩.基于弹性半无限空间的Mindlin位移解及复合材料力学原理,对劲性砂桩中混凝土芯桩轴向应力分布进行理论分析研究,得到劲性砂石桩芯桩轴力分布函数,讨论了不同荷载、混凝土芯桩标号、砂土弹性模量情况下芯桩轴向应力分布规律,并与现场芯桩轴向应力测试结果进行对比分析.研究表明:该理论分析结果与现场试验所显示的规律基本一致,验证了理论研究的合理性.该研究对于了解劲性砂桩的荷载传递规律和工作机制具有一定的理论价值.
加劲肋对轴心受压圆管柱脚应力的影响%The Influence of Stiffening Rib on Axial Compression Round String Stress
张向红
2014-01-01
Exposed column base is applied most frequently in al forms of column foot, and the calculation of column foot motherboard has become a critical problem. According to the different forms of stif ening rib, this paper compares the stress of axial compression string round feet, analyzes the effect of stif eners on the heel stress.%外露式柱脚是在所有柱脚形式中应用得最多的一种，柱脚底板的计算就成为一个至关重要的问题。本文针对不同的加劲肋形式，对轴心受压圆管柱脚的应力进行对比，分析加劲肋对柱脚应力的影响。
Kinkhabwala, Ali
2013-01-01
The most fundamental problem in statistics is the inference of an unknown probability distribution from a finite number of samples. For a specific observed data set, answers to the following questions would be desirable: (1) Estimation: Which candidate distribution provides the best fit to the observed data?, (2) Goodness-of-fit: How concordant is this distribution with the observed data?, and (3) Uncertainty: How concordant are other candidate distributions with the observed data? A simple unified approach for univariate data that addresses these traditionally distinct statistical notions is presented called "maximum fidelity". Maximum fidelity is a strict frequentist approach that is fundamentally based on model concordance with the observed data. The fidelity statistic is a general information measure based on the coordinate-independent cumulative distribution and critical yet previously neglected symmetry considerations. An approximation for the null distribution of the fidelity allows its direct conversi...
黄昌龙; 万小朋
2011-01-01
根据波音737CL飞机龙骨梁ADF环形天线组件固定孔区域的剥蚀特征,采用有限元分析和盐雾环境暴露试验研究了正应力在剥蚀中的作用.结果表明,纵向L方向及长横向LT方向压应力可加速7150铝合金的剥蚀的形成和扩展;L方向、LT方向拉应力以及短横向ST方向压应力抑制合金的剥蚀的形成和扩展.%Based on an investigation of the exfoliation corrosion（EFC） evolution around ADF antenna installing holes on aluminum alloy 7150-T77511 keel beam for aircraft B737CL,the effect of axial stress on the EFC was studied by means of finite element analysis and corrosion test in salt fogging environment.The results showed that compressive stress along directions L and LT accelerated EFC,whilst tensile stress along directions L and LT,and compressive stress along direction ST retarded EFC.
Optimization of residual heat removal pump axial thrust and axial bearing
Schubert, F.
1996-12-01
The residual heat removal (RHR) pumps of German 1300 megawatt pressurized-water reactor (PWR) power plants are of the single stage end suction type with volute casing or with diffuser and forged circular casing. Due to the service conditions the pumps have to cover the full capacity range as well as a big variation in suction static pressure. This results in a big difference in the axial thrust that has to be borne by the axial bearing. Because these pumps are designed to operate without auxiliary systems (things that do not exist can not fail), they are equipped with antifriction bearings and sump oil lubrication. To minimize the heat production within the bearing casing, a number of PWR plants have pumps with combined axial/radial bearings of the ball type. Due to the fact that the maximum axial thrust caused by static pressure and hydrodynamic forces on the impeller is too big to be borne by that type of axial bearing, the impellers were designed to produce a hydrodynamic axial force that counteracts the static axial force. Thus, the resulting axial thrust may change direction when the static pressure varies.
Residual stress around the cortical surface in bovine femoral diaphysis.
Yamada, Satoshi; Tadano, Shigeru
2010-04-01
Residual stress in living tissue plays an important role in mechanical strength. We have reported that residual stress exists in the bone tissue of a rabbit's tibiofibula. The purpose of this study is to measure the residual stress around the outer cortical region of bovine femoral diaphysis and to discuss the distribution of the stress. This work proposed the sin(2) psi method of X-ray diffraction to the measurement of residual stresses in bone tissue. In this method, residual stress can be estimated from the variation in the interplanar spacings orientated to a number of directions without the lattice strain in the stress direction. Four-point bending tests of strip specimens taken from bovine femoral diaphysis were carried out during X-ray irradiation in advance. In the proximal, middle, and distal sections of bovine femoral diaphyses, the residual stresses at the cortical surface were measured using characteristic Mo-Kalpha X-rays. The bending tests of strip specimens with X-ray irradiation showed that the method could reliably estimate residual stresses in the bone tissue. The residual stress of the bone axial direction was larger than that of the circumferential direction. The stresses in the middle part of five diaphyses along the bone axial direction were tensile. The maximum stress was 162 MPa at the lateral position and the minimum was 78 MPa at the posterior position. The residual stress in the bone axial direction varies around the circumferential region. In addition, the bone axial distributions of residual stresses were different in the proximal, middle, and distal sections of the individual femur. Furthermore, it was confirmed that residual stress in the bone tissue was released by the cutting out of the specimen. The residual stresses in bone tissue could be measured by this method. The results show that residual stress in the bone axial direction at the cortical surface in bovine femoral diaphysis is tensile and varies around the circumferential
J. Huffer
2004-09-28
The purpose of this calculation is to develop axial profiles for estimating the axial variation in burnup of a boiling water reactor (BWR) assembly spent nuclear fuel (SNF) given the average burnup of an assembly. A discharged fuel assembly typically exhibits higher burnup in the center and lower burnup at the ends of the assembly. Criticality safety analyses taking credit for SNF burnup must account for axially varying burnup relative to calculations based on uniformly distributed assembly average burnup due to the under-burned tips. Thus, accounting for axially varying burnup in criticality analyses is also referred to as accounting for the ''end effect'' reactivity. The magnitude of the reactivity change due to ''end effect'' is dependent on the initial assembly enrichment, the assembly average burnup, and the particular axial profile characterizing the burnup distribution. The set of bounding axial profiles should incorporate multiple BWR core designs and provide statistical confidence (95 percent confidence that 95 percent of the population is bound by the profile) that end nodes are conservatively represented. The profiles should also conserve the overall burnup of the fuel assembly. More background on BWR axial profiles is provided in Attachment I.
The Stress and Stiffness Analysis of Diaphragm
Qu Dongyue
2017-01-01
Full Text Available Diaphragm coupling with its simple structure, small size, high reliability, which can compensate for its input and output displacement deviation by its elastic deformation, is widely used in aerospace, marine, and chemical etc. This paper uses the ANSYS software and its APDL language to analysis the stress distribution when the diaphragm under the load of torque, axial deviation, centrifugal force, angular deviation and multiple loads. We find that the value of maximum stress usually appears in the outer or inner transition region and the axial deviation has a greater influence to the distribution of the stress. Based on above, we got three kinds of stiffness for axial, angular and torque, which the stiffness of diaphragm is nearly invariable. The results can be regard as an important reference for design and optimization of diaphragm coupling.
[Management of axial spondyloarthritis].
Kiltz, U; Baraliakos, X; Braun, J
2016-11-01
The term spondyloarthritis (SpA) is now increasingly used to classify and diagnose patients who are characterized by inflammation in the axial skeleton and peripheral manifestations (arthritis and enthesitis). The management of SpA should be tailored according to the current manifestations of the disease, the disease activity and functional impairment. The current article focuses on diagnosis and therapy in patients with axial SpA. Diagnostic procedures are discussed in light of diagnostic utility and feasibility in daily routine care. Cornerstones of treatment in patients with axial SpA are a combination of regular exercise and pharmacological treatment options aiming at anti-inflammatory strategies.
Notari, Alessio; Tywoniuk, Konrad
2016-12-01
We analyze in detail the background cosmological evolution of a scalar field coupled to a massless abelian gauge field through an axial term phi/fγ F ~F, such as in the case of an axion. Gauge fields in this case are known to experience tachyonic growth and therefore can backreact on the background as an effective dissipation into radiation energy density ρR, which can lead to inflation without the need of a flat potential. We analyze the system, for momenta k smaller than the cutoff fγ, including the backreaction numerically. We consider the evolution from a given static initial condition and explicitly show that, if fγ is smaller than the field excursion phi0 by about a factor of at least Script O (20), there is a friction effect which turns on before the field can fall down and which can then lead to a very long stage of inflation with a generic potential. In addition we find superimposed oscillations, which would get imprinted on any kind of perturbations, scalars and tensors. Such oscillations have a period of 4-5 efolds and an amplitude which is typically less than a few percent and decreases linearly with fγ. We also stress that the curvature perturbation on uniform density slices should be sensitive to slow-roll parameters related to ρR rather than dot phi2/2 and we discuss the existence of friction terms acting on the perturbations, although we postpone a calculation of the power spectrum and of non-gaussianity to future work and we simply define and compute suitable slow roll parameters. Finally we stress that this scenario may be realized in the axion case, if the coupling 1/fγ to U(1) (photons) is much larger than the coupling 1/fG to non-abelian gauge fields (gluons), since the latter sets the range of the potential and therefore the maximal allowed phi0~ fG.
Axial Halbach Magnetic Bearings
Eichenberg, Dennis J.; Gallo, Christopher A.; Thompson, William K.
2008-01-01
Axial Halbach magnetic bearings have been investigated as part of an effort to develop increasingly reliable noncontact bearings for future high-speed rotary machines that may be used in such applications as aircraft, industrial, and land-vehicle power systems and in some medical and scientific instrumentation systems. Axial Halbach magnetic bearings are passive in the sense that unlike most other magnetic bearings that have been developed in recent years, they effect stable magnetic levitation without need for complex active control.
Tolan, Dina; Gandin, Valentina; Morrison, Liam; El-Nahas, Ahmed; Marzano, Cristina; Montagner, Diego; Erxleben, Andrea
2016-07-01
The use of Pt(IV) complexes as pro-drugs that are activated by intracellular reduction is a widely investigated approach to overcome the limitations of Pt(II) anticancer agents. A series of ten mono- and bis-carboxylated Pt(IV) complexes with axial indole-3-acetic acid (IAA) and indole-3-propionic acid (IPA) ligands were synthesized and characterized by elemental analysis, ESI-MS, FT-IR, 1H and 195Pt NMR spectroscopy. Cellular uptake, DNA platination and cytotoxicity against a panel of human tumor cell lines were evaluated. All the complexes are able to overcome cisplatin-resistance and the most potent complex, cis,cis,trans-[Pt(NH3)2Cl2(IPA)(OH)] was on average three times more active than cisplatin. Mechanistic studies revealed that the trend in cytotoxicity of the Pt(IV) complexes is primarily consistent with their ability to accumulate into cancer cells and to increase intracellular basal reactive oxygen species levels, which in turn results in the loss of mitochondrial membrane potential and apoptosis induction. The role of the indole acid ligand as a redox modulator is discussed.
ON WALL SHEAR STRESS OF ARTERY
Liu Zhao-rong; Liu Bao-yu; Qin Kai-rong
2003-01-01
In this paper, a method was proposed that the wall shear stress of artery could be determined by measuring the centerline axial velocity and radial motion of arterial wall simultaneously.The method is simple in application and can get higher precision when it is used to determine the shear stress of arterial wall in vivo.As an example, the shear stress distribution in periodic oscillatory flow of human carotid was calculated and discussed.The computed results show that the shear stress distribution at any given instant is almost uniform and will be zero at the centerline and tends to maximum at the vessel wall.
Altered Axial Skeletal Development
The axial skeleton is routinely examined in standard developmental toxicity bioassays and has proven to be sensitive to a wide variety of chemical agents. Dysmorphogenesis in the skull, vertebral column and ribs has been described in both human populations and in laboratory anima...
Konstandinos G. Raptis
2012-01-01
Full Text Available Purpose of this study is the consideration of loading and contact problems encountered at rotating machine elements and especially at toothed gears. The later are some of the most commonly used mechanical components for rotary motion and power transmission. This fact proves the necessity for improved reliability and enhanced service life, which require precise and clear knowledge of the stress field at gear tooth. This study investigates the maximum allowable stresses occurring during spur gear tooth meshing computed using Niemannâs formulas at Highest Point of Single Tooth Contact (HPSTC. Gear material, module, power rating and number of teeth are considered as variable parameters. Furthermore, the maximum allowable stresses for maximum power transmission conditions are considered keeping the other parameters constant. After the application of Niemannâs formulas to both loading cases, the derived results are compared to the respective estimations of Finite Element Method (FEM using ANSYS software. Comparison of the results derived from Niemannâs formulas and FEM show that deviations between the two methods are kept at low level for both loading cases independently of the applied power (either random or maximum and the respective tangential load.
Matsuyoshi MORI
1997-04-01
Full Text Available Estudou-se comparativamente, pelo método do elemento finito em modelo bidimensional de segundo pré-molar inferior, a distribuição de tensões internas, geradas sob carga axial de 30 kgf em três pontos (contatos principal e estabilizante, em dente natural hígido e em dente endodonticamente tratado. O programa utilizado para o processamento do elemento finito foi o SAP90. Os resultados indicaram maior acúmulo de tensões na metade vestibular, tanto no dente hígido quanto no dente restaurado. As tensões foram mais intensas sob o ponto de aplicação de cargas nos dois modelos. No dente restaurado, as tensões foram maiores devido ao maior módulo de elasticidade dos materiais restauradores, demonstrando que existem diferenças na distribuição das tensões no dente e na base óssea dos dois modelosThis study compared the internal stress distribution in a sound tooth with that in an endodontically treated tooth, by the finite element method, in a two-dimensional, lower premolar model, under an axial load of 30 kgf applied to three points (primary occlusal contact and stabilizing occlusal contact. Results indicated that there was a greater cumulation of stress in the buccal half of both teeth. In both models, peak stress was observed at the places where loads were applied. The restored tooth presented greater stress due to the greater Young's modulus of the utilized restoring materials. It was therefore demonstrated that there are differences in the distribution of internal stress between both models
Surface nanoscale axial photonics
Sumetsky, M
2011-01-01
Dense photonic integration promises to revolutionize optical computing and communications. However, efforts towards this goal face unacceptable attenuation of light caused by surface roughness in microscopic devices. Here we address this problem by introducing Surface Nanoscale Axial Photonics (SNAP). The SNAP platform is based on whispering gallery modes circulating around the optical fiber surface and undergoing slow axial propagation readily described by the one-dimensional Schr\\"odinger equation. These modes can be steered with dramatically small nanoscale variation of the fiber radius, which is quite simple to introduce in practice. The extremely low loss of SNAP devices is achieved due to the fantastically low surface roughness inherent in a drawn fiber surface. In excellent agreement with the developed theory, we experimentally demonstrate localization of light in quantum wells, halting light by a point source, tunneling through potential barriers, dark states, etc. This demonstration, prototyping basi...
Temporal and spatial patterns of zooplankton in the Chesapeake Bay turbidity maximum
M. R. Roman; D. V. Holliday; L. P. Sanford
2001-01-01
We measured the distribution of hydrographic parameters, currents, phytoplankton fluorescence, suspended sediments and zooplankton in axial transects through the Chesapeake Bay estuarine turbidity maximum (ETM) seasonally...
Masi, Alfonse T
2014-01-01
Ankylosing spondylitis and axial spondyloarthropathy have characteristic age- and sex-specific onset patterns, typical entheseal lesions, and marked heritability, but the integrative mechanisms causing the pathophysiological and structural alterations remain largely undefined. Myofascial tissues are integrated in the body into webs and networks which permit transmission of passive and active tensional forces that provide stabilizing support and help to control movements. Axial myofascial hypertonicity was hypothesized as a potential excessive polymorphic trait which could contribute to chronic biomechanical overloading and exaggerated stresses at entheseal sites. Such a mechanism may help to integrate many of the characteristic host, pathological, and structural features of ankylosing spondylitis and axial spondyloarthritis. Biomechanical stress and strain were recently documented to correlate with peripheral entheseal inflammation and new bone formation in a murine model of spondyloarthritis. Ankylosing spondylitis has traditionally been classified by the modified New York criteria, which require the presence of definite radiographic sacroiliac joint lesions. New classification criteria for axial spondyloarthritis now include patients who do not fulfill the modified New York criteria. The male-to-female sex ratios clearly differed between the two patient categories - 2:1 or 3:1 in ankylosing spondylitis and 1:1 in non-radiographic axial spondyloarthritis - and this suggests a spectral concept of disease and, among females, milder structural alterations. Magnetic resonance imaging of active and chronic lesions in ankylosing spondylitis and axial spondyloarthritis reveals complex patterns, usually interpreted as inflammatory reactions, but shows similarities to acute degenerative disc disease, which attributed to edema formation following mechanical stresses and micro-damage. A basic question is whether mechanically induced microinjury and immunologically mediated
Razzaq, Zia
1989-01-01
Straight or curved hat-section members are often used as structural stiffeners in aircraft. For instance, they are employed as stiffeners for the dorsal skin as well as in the aerial refueling adjacent area structure in F-106 aircraft. The flanges of the hat-section are connected to the aircraft skin. Thus, the portion of the skin closing the hat-section interacts with the section itself when resisting the stresses due to service loads. The flexural fatigue life of such a closed section is estimated using materially nonlinear axial fatigue characteristics. It should be recognized that when a structural shape is subjected to bending, the fatigue life at the neutral axis is infinity since the normal stresses are zero at that location. Conversely, the fatigue life at the extreme fibers where the normal bending stresses are maximum can be expected to be finite. Thus, different fatigue life estimates can be visualized at various distances from the neural axis. The problem becomes compounded further when significant portions away from the neutral axis are stressed into plastic range. A theoretical analysis of the closed hat-section subjected to flexural cyclic loading is first conducted. The axial fatigue characteristics together with the related axial fatigue life formula and its inverted form given by Manson and Muralidharan are adopted for an aluminum alloy used in aircraft construction. A closed-form expression for predicting the flexural fatigue life is then derived for the closed hat-section including materially nonlinear action. A computer program is written to conduct a study of the variables such as the thicknesses of the hat-section and the skin, and the type of alloy used. The study has provided a fundamental understanding of the flexural fatigue life characteristics of a practical structural component used in aircraft when materially nonlinear action is present.
ANALYSIS OF PULSATILE BLOOD FLOW IN AXIALLY MOVING ARTERIES
无
2000-01-01
In order to study motional properties of pulsatile blood flow in axially moving arteries, the authors derived some expressions of the pulsatile blood flow from the basic equations of motion for blood and vascular walls, including an axial blood velocity equation, a flow rate equation and a wall shear stress equation, which described not only the overall axial movement of the arteries but also the elastic properties of the vascular walls, discussed the effects of the arterial wall elasticity on the wall shear stress in coronary arteries in terms of these expressions, and analyzed changes of motional properties of pulsatile blood flow between an elastic arterial tube model and a rigid tube model. The results proved the inference by J.E. Moore Jr. et al. (1994) that the axial movement of arteries be as important in determining coronary artery hemodynamics as the elastic property of the vascular wall.
Walt Wells
2008-01-01
Full Text Available Our objective in this paper is to solve a second order differential equation for a long, simply supported column member subjected to a lateral axial load using Heun's numerical method. We will use the solution to find the critical load at which the column member will fail due to buckling. We will calculate this load using Euler's derived analytical approach for an exact solution, as well as Euler's Numerical Method. We will then compare the three calculated values to see how much they deviate from one another. During the critical load calculation, it will be necessary to calculate the moment of inertia for the column member.
Operating characteristics of heavy loaded cylindrical journal bearing with variable axial profile
Stanislaw Strzelecki
2005-12-01
Full Text Available During the operation of turbounit its bearings displace as a result of heat elongation of bearings supports. It changes the static deflection line of rotor determined during assembly of the turbounit, causing an increase in the stresses on the bearing edges and a decrease in the dynamic state of the machine. One of possibilities to avoid the edge stresses is to apply the bearings with variable axial profile, e.g. hyperboloidal, convex profile in the axial cross-section of bearing. Application of journal bearings with hyperboloidal profile allows to extend the bearing operation range without the stress concentration on the edges of bush. These bearings successfully carry the extreme load in conditions of misaligned axis of journal and the bush eliminating the necessity of using self-aligning bearings. Operating characteristics of bearing include the resulting force, attitude angle, oil film pressure and temperature distributions, minimum oil film thickness, maximum oil film temperature. In literature there is a lack of data on the operating characteristics of heavy loaded hyperboloidal journal bearings operating at the conditions of adiabatic oil film and static equilibrium position of the journal. For the hyperboloidal bearing the operating characteristics have been obtained. Different values of length to diameter ratio, assumed shape and inclination ratio coefficients have been assumed. Iterative solution of the Reynolds', energy and viscosity equations was applied. Adiabatic oil film, laminar flow in the bearing gap as well as aligned and misaligned orientation of journal in the bush were considered.
Buckling localization in a cylindrical panel under axial compression
Tvergaard, Viggo; Needleman, A.
2000-01-01
Localization of an initially periodic buckling pattern is investigated for an axially compressed elastic-plastic cylindrical panel of the type occurring between axial stiffeners on cylindrical shells. The phenomenon of buckling localization and its analogy with plastic flow localization in tensile...... test specimens is discussed in general. For the cylindrical panel, it is shown that buckling localization develops shortly after a maximum load has been attained, and this occurs for a purely elastic panel as well as for elastic-plastic panels. In a case where localization occurs after a load maximum...
Changes in internal stress distributions during yielding of square prismatic gold nano-specimens
Batra, R.C., E-mail: rbatra@vt.edu [Department of Engineering Science and Mechanics, M/C 0219, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061 (United States); Pacheco, A.A. [Universidad del Norte, Department of Mechanical Engineering, Barranquilla (Colombia)
2010-05-15
We use molecular statics simulations with the tight-binding potential to analyze stress evolution in nanosize square prismatic gold specimens of different aspect ratios (length/width) deformed in either simple tension/compression or tension/compression. In the former case atoms on end faces are displaced axially but are free to move laterally, and in the latter case atoms on end faces are restrained from moving laterally during their axial displacement. It is found that the stress distribution in the unloaded reference configuration is non-uniform, and it satisfies the local and the global equilibrium equations. Large values of the von Mises stress and the maximum shear stress occur on atoms located at the third layer beneath the traction free surfaces forming different patterns for specimens loaded in tension and compression. The specimen is assumed to yield when its total strain energy drops noticeably. Maximum values of the von Mises stress and the maximum shear stress at yielding are essentially independent of specimen's length for specimens deformed in tension. For specimens deformed in compression, wave-like patterns of stresses along the axial centroidal axis are observed when the specimen yields.
Build Axial Gradient Field by Using Axial Magnetized Permanent Rings
无
2002-01-01
Axial magnetic field produced by an axial magnetized permanent ring was studied. For two permanent rings, if they are magnetized in the same directions, a nearly uniform axial field can be produced. If they are magnetized in opposite direction,an axial gradient magnetic field can be generated, with the field range changing from -B0 to B0. A permanent magnet with a high axial gradient field was fabricated, the measured results agree with the PANDIRA calculation very well. For wider usage,it is desirable for the field gradient to be changed. Some methods to produce the variable gradient field are presented. These kinds of axial gradient magnetic field can also be used as a beam focusing for linear accelerator if the periodic field can be produced along the beam trajectory. The axial magnetic field is something like a solenoid, large stray field will leak to the outside environment if no method is taken to control them. In this paper, one method is illustrated to shield off the outside leakage field.
Notari, Alessio
2016-01-01
We analyze in detail the background cosmological evolution of a scalar field coupled to a massless abelian gauge field through an axial term $\\frac{\\phi}{f_\\gamma} F \\tilde{F}$, such as in the case of an axion. Gauge fields in this case are known to experience tachyonic growth and therefore can backreact on the background as an effective dissipation into radiation energy density $\\rho_R$, which which can lead to inflation without the need of a flat potential. We analyze the system, for momenta $k$ smaller than the cutoff $f_\\gamma$, including numerically the backreaction. We consider the evolution from a given static initial condition and explicitly show that, if $f_\\gamma$ is smaller than the field excursion $\\phi_0$ by about a factor of at least ${\\cal O} (20)$, there is a friction effect which turns on before that the field can fall down and which can then lead to a very long stage of inflation with a generic potential. In addition we find superimposed oscillations, which would get imprinted on any kind of...
Composite Axial Flow Propulsor for Small Aircraft
2005-01-01
This work focuses on the design of an axial flow ducted fan driven by a reciprocating engine. The solution minimizes the turbulization of the flow around the aircraft. The fan has a rotor - stator configuration. Due to the need for low weight of the fan, a carbon/epoxy composite material was chosen for the blades and the driving shaft.The fan is designed for optimal isentropic efficiency and free vortex flow. A stress analysis of the rotor blade was performed using the Finite Element Method....
Study of axial magnetic effect
Braguta, Victor [IHEP, Protvino, Moscow region, 142284 Russia ITEP, B. Cheremushkinskaya street 25, Moscow, 117218 (Russian Federation); School of Biomedicine, Far Eastern Federal University, Ajax 10 Building 25, Russian island, Vladivostok, 690922 (Russian Federation); Chernodub, M. N. [CNRS, Laboratoire de Mathématiques et Physique Théorique, Université François-Rabelais Tours, Fédération Denis Poisson, Parc de Grandmont, 37200 Tours, France Department of Physics and Astronomy, University of Gent, Krijgslaan 281, S9, B-9000 Gent (Belgium); School of Biomedicine, Far Eastern Federal University, Ajax 10 Building 25, Russian island, Vladivostok, 690922 (Russian Federation); Goy, V. A. [School of Natural Sciences, Far Eastern Federal University, Sukhanova street 8, Vladivostok, 690950 (Russian Federation); Landsteiner, K. [Instituto de Física Teórica UAM/CSIC, C/ Nicolás Cabrera 13-15, Universidad Autónoma de Madrid, Cantoblanco, 28049 Madrid (Spain); Molochkov, A. V. [School of Biomedicine, Far Eastern Federal University, Ajax 10 Building 25, Russian island, Vladivostok, 690922 (Russian Federation); Ulybyshev, M. [ITEP, B. Cheremushkinskaya street 25, Moscow, 117218 Russia Institute for Theoretical Problems of Microphysics, Moscow State University, Moscow, 119899 (Russian Federation)
2016-01-22
The Axial Magnetic Effect manifests itself as an equilibrium energy flow of massless fermions induced by the axial (chiral) magnetic field. Here we study the Axial Magnetic Effect in the quenched SU(2) lattice gauge theory with massless overlap fermions at finite temperature. We numerically observe that in the low-temperature hadron phase the effect is absent due to the quark confinement. In the high-temperature deconfinement phase the energy flow is an increasing function of the temperature which reaches the predicted asymptotic T{sup 2} behavior at high temperatures. We find, however, that energy flow is about one order of magnitude lower compared to a theoretical prediction.
... diabetes. Shopdiabetes.org: Your Stress-Free System for Family Dinners! - 2017-03-book-oclock-scramble.html Shopdiabetes.org Your Stress-Free System for Family Dinners! A year of delicious meals to help prevent ...
... sudden negative change, such as losing a job, divorce, or illness Traumatic stress, which happens when you ... stress, so you can avoid more serious health effects. NIH: National Institute of Mental Health
Slow axial drift in three-dimensional granular tumbler flow
Zaman, Zafir; D'Ortona, Umberto; Umbanhowar, Paul B.; Ottino, Julio M.; Lueptow, Richard M.
2013-07-01
Models of monodisperse particle flow in partially filled three-dimensional tumblers often assume that flow along the axis of rotation is negligible. We test this assumption, for spherical and double cone tumblers, using experiments and discrete element method simulations. Cross sections through the particle bed of a spherical tumbler show that, after a few rotations, a colored band of particles initially perpendicular to the axis of rotation deforms: particles near the surface drift toward the pole, while particles deeper in the flowing layer drift toward the equator. Tracking of mm-sized surface particles in tumblers with diameters of 8-14 cm shows particle axial displacements of one to two particle diameters, corresponding to axial drift that is 1-3% of the tumbler diameter, per pass through the flowing layer. The surface axial drift in both double cone and spherical tumblers is zero at the equator, increases moving away from the equator, and then decreases near the poles. Comparing results for the two tumbler geometries shows that wall slope causes axial drift, while drift speed increases with equatorial diameter. The dependence of axial drift on axial position for each tumbler geometry is similar when both are normalized by their respective maximum values.
FINITE ELEMENT ANALYSIS OF AXIAL FEED BAR ROLLING
C.G. Xu; G.H. Liu; G.S. Ren; Z. Shen; C.P. Ma; W. W. Ren
2007-01-01
A flexible technique of hot working of bars by axial feed rolling was introduced. The processdeformation, strain field, stress field, and temperature field of the parts are analyzed by finite elementmethod (FEM)-simulation software DEFORM-3D. The material flow rule and tool load have beeninvestigated.
Maximum Autocorrelation Factorial Kriging
Nielsen, Allan Aasbjerg; Conradsen, Knut; Pedersen, John L.
2000-01-01
This paper describes maximum autocorrelation factor (MAF) analysis, maximum autocorrelation factorial kriging, and its application to irregularly sampled stream sediment geochemical data from South Greenland. Kriged MAF images are compared with kriged images of varimax rotated factors from...
Abbas, Musharaf; Hasham, Hasan Junaid; Baig, Yasir
2016-02-01
Numerical-based finite element investigation has been conducted to explain the effect of bond coat thickness on stress distribution in traditional and nanostructured yttria-stabilized zirconia (YSZ)-based thermal barrier coatings (TBC). Stress components have been determined to quantitatively analyze the mechanical response of both kinds of coatings under the thermal shock effect. It has been found that maximum radial tensile and compressive stresses that exist at thermally grown oxide (TGO)/bond coat interface and within TGO respectively decrease with an increase in bond coat thickness. Effect of bond coat thickness on axial tensile stresses is not significant. However, axial compressive stresses that exist at the edge of the specimen near bond coat/substrate interface decrease appreciably with the increase in bond coat thickness. Residual stress profile as a function of bond coat thickness is further explained for comparative analysis of both coatings to draw some useful conclusions helpful in failure studies of TBCs.
2007-11-02
in axial turbomachines and use the data to address turbulence and flow modeling issues that are specific to such complex environments. The motivation...stress modeling for LES. The report describes in detail our unique two-stage axial- turbomachine flow visualization facility, specifying the instruments
Dynamic response of the occipito-atlanto-axial (C0-C1-C2) complex in right axial rotation.
Chang, H; Gilbertson, L G; Goel, V K; Winterbottom, J M; Clark, C R; Patwardhan, A
1992-05-01
The torque-angular deformation in right axial rotation until failure of the ligamentous occipito-atlanto-axial complex subjected to variable loading rate (dynamic) axial torque was characterized using a biaxial MTS system. A special fixture and gear box that permitted right axial rotation of the specimen until failure without imposing any additional constraints were used to obtain the data. The specimens were divided into three groups and tested until failure at three different dynamic loading rates: 50, 100, and 400 degrees/s. A previous study by the authors provided data for quasi-static (4 degrees/s) loading conditions. The torque versus rotation curves can be divided into two straight regions and two transition zones. The plots clearly indicated that at loading rates higher than 4 degrees/s, the specimens became stiffer in the region of steadily increasing resistance prior to failure. The increase in stiffness was maximum at 100 degrees/s. The stiffness decreased somewhat at 400 degrees/s in comparison with 100 degrees/s, but this decrease was not significant. The resulting torque-right axial rotation curves were also examined to estimate the magnitude of maximum resistance (torque) and the corresponding angular rotation value. The average maximum resistance torque increased from 13.6 Nm at 4 degrees/s to 27.8 Nm at 100 degrees/s. The corresponding right angular rotation data (65-78 degrees), however, did not show any significant variation with loading rate. Posttest dissection of the specimens indicated that the type of injury observed was related to the rate of axial loading imposed on a specimen during testing.(ABSTRACT TRUNCATED AT 250 WORDS)
Instability of Meridional Axial System in f(R) Gravity
Sharif, M
2015-01-01
We analyze dynamical instability of non-static reflection axial stellar structure by taking into account generalized Euler's equation in metric $f(R)$ gravity. Such an equation is obtained by contracting Bianchi identities of usual anisotropic and effective stress-energy tensors, which after using radial perturbation technique gives modified collapse equation. In the realm of $R+\\epsilon R^n$ gravity model, we investigate instability constraints at Newtonian and post-Newtonian approximations. We find that instability of meridional axial self-gravitating system depends upon static profile of structure coefficients while $f(R)$ extra curvature terms induce stability to the evolving celestial body.
Silicon nanowire-based ring-shaped tri-axial force sensor for smart integration on guidewire
Han, Beibei; Yoon, Yong-Jin; Hamidullah, Muhammad; Tsu-Hui Lin, Angel; Park, Woo-Tae
2014-06-01
A ring-shaped tri-axial force sensor with a 200 µm × 200 µm sensor area using silicon nanowires (SiNWs) as piezoresistive sensing elements is developed and characterized. The sensor comprises a suspended ring structure located at the center of four suspended beams that can be integrated on the distal tip of a guidewire by passing through the hollow core of the sensor. SiNWs with a length of 6 µm and a cross section of 90 nm × 90 nm are embedded at the anchor of each silicon bridge along direction as the piezoresistive sensing element. Finite element analysis has been used to determine the location of maximum stress and the simulation results are verified with the experimental measurements. Taking advantage of the high sensitivity of SiNWs, the fabricated ring-shaped sensor is capable of detecting small displacement in nanometer ranges with a sensitivity of 13.4 × 10-3 µm-1 in the z-direction. This tri-axial force sensor also shows high linearity (>99.9%) to the applied load and no obvious hysteresis is observed. The developed SiNW-based tri-axial force sensor provides new opportunities to implement sensing capability on medical instruments such as guidewires and robotic surgical grippers, where ultra-miniaturization and high sensitivity are essential.
Relativistic RPA in axial symmetry
Arteaga, D Pena; 10.1103/PhysRevC.77.034317
2009-01-01
Covariant density functional theory, in the framework of self-consistent Relativistic Mean Field (RMF) and Relativistic Random Phase approximation (RPA), is for the first time applied to axially deformed nuclei. The fully self-consistent RMF+RRPA equations are posed for the case of axial symmetry and non-linear energy functionals, and solved with the help of a new parallel code. Formal properties of RPA theory are studied and special care is taken in order to validate the proper decoupling of spurious modes and their influence on the physical response. Sample applications to the magnetic and electric dipole transitions in $^{20}$Ne are presented and analyzed.
Axial Current and Noether Charge
Mahato, Prasanta
2012-01-01
A decade ago, a Lagrangian density has been proposed by the author where only the local symmetries of the Lorentz subgroup of (A)ds group is retained. This formalism has been found to produce some results encompassing that of standard Einstein-Hilbert formalism. In the present article, the conserved axial vector matter currents, constructed in some earlier paper, have been found to be a result of Noether's theorem. PACS: 04.20.Fy, 04.20.Cv, 11.40.-q Keywords: Torsion, Axial Current, Noether's Theorem
Unsteady flows in a single-stage transonic axial-flow fan stator row
Hathaway, Michael Dale
Detailed measurements of the unsteady velocity field within the stator flow of a transonic axial-flow fan were acquired using a laser anemometer. They were obtained on axisymmetric surfaces located at 10 and 50 percent span from the shroud, with the fan operating at maximum efficiency at design speed. The ensemble-average and variance of the measured velocities are used to identify rotor-wake-generated (deterministic) unsteadiness and turbulence, respectively. Correlations of both deterministic and turbulent velocity fluctuations provide information on the characteristics of unsteady interactions within the stator row. These correlations are derived from the Navier-Stokes equation in a manner similar to deriving the Reynolds stress terms, whereby various averaging operators are used to average the aperiodic, deterministic, and turbulent velocity fluctuations known to be present in multistage turbomachines. The correlations of deterministic and turbulent velocity fluctuations throughout the axial fan stator row are presented. In particular, amplification and attenuation of both types of unsteadiness are shown to occur within the stator blade passage.
Keller, Hanne Dauer
2015-01-01
Kapitlet handler om stress som følelse, og det trækker primært på de få kvalitative undersøgelser, der er lavet af stressforløb.......Kapitlet handler om stress som følelse, og det trækker primært på de få kvalitative undersøgelser, der er lavet af stressforløb....
Keller, Hanne Dauer
2015-01-01
Kapitlet handler om stress som følelse, og det trækker primært på de få kvalitative undersøgelser, der er lavet af stressforløb.......Kapitlet handler om stress som følelse, og det trækker primært på de få kvalitative undersøgelser, der er lavet af stressforløb....
Axially Symmetric, Spatially Homothetic Spacetimes
Wagh, S M; Wagh, Sanjay M.; Govinder, Keshlan S.
2002-01-01
We show that the existence of appropriate spatial homothetic Killing vectors is directly related to the separability of the metric functions for axially symmetric spacetimes. The density profile for such spacetimes is (spatially) arbitrary and admits any equation of state for the matter in the spacetime. When used for studying axisymmetric gravitational collapse, such solutions do not result in a locally naked singularity.
Thermophoresis of Axially Symmetric Bodies
2007-11-02
Sweden Abstract. Thermophoresis of axially symmetric bodies is investigated to first order in the Knudsen-mimber, Kn. The study is made in the limit...derived. Asymptotic solutions are studied. INTRODUCTION Thermophoresis as a phenomenon has been known for a long time, and several authors have approached
Axial structure of the nucleon
Veronique Bernard; Latifa Elouadrhiri; Ulf-G Meissner
2002-01-01
We review the current status of experimental and theoretical understanding of the axial nucleon structure at low and moderate energies. Topics considered include (quasi)elastic (anti)neutrino-nucleon scattering, charged pion electroproduction off nucleons and ordinary as well as radiative muon capture on the proton.
Composite Axial Flow Propulsor for Small Aircraft
R. Poul
2005-01-01
Full Text Available This work focuses on the design of an axial flow ducted fan driven by a reciprocating engine. The solution minimizes the turbulization of the flow around the aircraft. The fan has a rotor - stator configuration. Due to the need for low weight of the fan, a carbon/epoxy composite material was chosen for the blades and the driving shaft.The fan is designed for optimal isentropic efficiency and free vortex flow. A stress analysis of the rotor blade was performed using the Finite Element Method. The skin of the blade is calculated as a laminate and the foam core as a solid. A static and dynamic analysis were made. The RTM technology is compared with other technologies and is described in detail.
Aerothermal optimization of partially shrouded axial turbines[Dissertation 17138
Porreca, L.
2007-07-01
This work presents the results of an aerodynamic and thermal study of three different shrouded axial turbine configurations (turbomachinery). The blade geometry of the turbine stages and the tip clearances of the test cases under investigation are identical although the shroud design is different. The first test case (RRD) is representative of a full shroud geometry while the second (CPS) and third (EPS) test cases adopt different partial shroud arrangements. In the EPS case, a shroud platform is added to cover the blade throat. Partial shrouds are sometimes used in industrial application in order to benefit from the aerodynamic advantage of shrouded configuration as well as reducing thermal load and mechanical stress on the blade root. However, the optimal compromise between mechanical issues and aerodynamic performances is still an open issue due to the resulting highly 3-dimensional unsteady flow field, difficulty of achieve an optimal cooling and severe heat load on the shroud sealing fins. An experimental investigation is carried out in order to quantify the effect of the shroud geometry on the aerodynamic performances and to study the resultant flow field in all test cases. The analysis has been conducted in an experimental low-speed axial turbine facility at the Turbomachinery Laboratory at ETH Zurich. Steady and fast response aerodynamic probe technology (FRAP) has been used to characterize the flow field. Moreover, a stereoscopic PIV technique has been design and applied in this experimental facility for the first time. The flow field analysis shows that the effect of the shroud geometry is significant from 60% blade height span to the tip. Tip leakage vortex in the first rotor is originated in the partial shroud test cases while the full shroud case present only a weak indigenous tip passage vortex. Secondary flows development in the following second stator resulted to be greatly affected by the leakage/main flow interaction of the first rotor. The
Maximum Autocorrelation Factorial Kriging
Nielsen, Allan Aasbjerg; Conradsen, Knut; Pedersen, John L.; Steenfelt, Agnete
2000-01-01
This paper describes maximum autocorrelation factor (MAF) analysis, maximum autocorrelation factorial kriging, and its application to irregularly sampled stream sediment geochemical data from South Greenland. Kriged MAF images are compared with kriged images of varimax rotated factors from an ordinary non-spatial factor analysis, and they are interpreted in a geological context. It is demonstrated that MAF analysis contrary to ordinary non-spatial factor analysis gives an objective discrimina...
Optimization of axial blowers. Optimierung von Axial-Ventilatoren
Bolte, W.
1992-08-01
For the optimum possible design of axial blowers, trials are evaluated in the article, which are based on the grid profile examined by N. Scholz. The computation for the pressure number and the primary degree of efficiency are shown as well as the evaluation of the effect of the Reynolds and mach number on the degree of efficiency and determination of the secondary losses. In a final example, the dimensions of a blower are computed from the data determined during the trials. (orig.).
Jensen, Line Skov; Lova, Lotte; Hansen, Zandra Kulikovsky; Schønemann, Emilie; Larsen, Line Lyngby; Colberg Olsen, Maria Sophia; Juhl, Nadja; Magnussen, Bogi Roin
2012-01-01
Stress er en tilstand som er meget omdiskuteret i samfundet, og dette besværliggør i en vis grad konkretiseringen af mulige løsningsforslag i bestræbelsen på at forebygge den såkaldte folkesygdom. Hovedkonklusionen er, at selv om der bliver gjort meget for at forebygge, er der ikke meget der aktivt kan sættes i værk for at reducere antallet af stressramte, før en fælles forståelse af stressårsager og effektiv stresshåndtering er fremlagt. Problemformuleringen er besvaret gennem en undersø...
View of the Axial Field Spectrometer
1980-01-01
The Axial Field Spectrometer, with the vertical uranium/scintillator calorimeter and the central drift chamber retracted for service. One coil of the Open Axial Field Magnet is just visible to the right.
[Axial spondyloarthritis and ankylosing spondylitis].
Nordström, Dan; Kauppi, Markku
2010-01-01
Current classification criteria for ankylosing spondylitis do not allow diagnosis before radiographic changes are visible in sacroiliacal joints. The the new axial spondyloarthropathy (SpA) criteria include axial SpA without radiographic changes as well as established ankylosing spondylitis, recognizing them as a continuum of the same disease. This is of major importance as the burden of early SpA is comparable to that of later stage disease. Diagnosis relies on inflammatory MRI findings which is the most significant change compared to earlier criteria. Emerging data on the efficacy of tumor necrosis factor (TNF) alpha blocking therapies already in early but also in established disease have given new promising alternatives for treatment of this often very cumbersome disease, that rarely responds to classic DMARDs.
Axial Spondyloarthritis: An Evolving Concept
Nelly Ziadé
2015-07-01
Full Text Available Axial spondyloarthritis (AxSpA is the prototype of a family of inter-related yet heterogeneous diseases sharing common clinical and genetic manifestations: the spondyloarthritides (SpAs. The condition mainly affects the sacroiliac joints and axial skeleton, and has a clear classification scheme, wider epidemiological data, and distinct therapeutic guidelines when compared with other SpAs. However, the concept of AxSpA has not been immutable over time and has evolved tremendously on many levels over the past decades. This review identifies the evolution of the AxSpA concept at two levels. First, at the level of classification, the old classifications and rationales leading to the current Assessment of SpondyloArthritis international Society (ASAS classification are reviewed, and the advantages and drawbacks are discussed. Second, at the therapeutic level, current and future treatments are described and treatment strategies are discussed.
Plasticity around an Axial Surface Crack in a Cylindrical Shell
Krenk, Steen
1979-01-01
This paper presents a plasticity model for deep axial surface cracks in pressurised pipes. The model is used in an investigation of the relative merits of fracture criteria based on COD and plastic instability. Recent investigations have shown that the inconsistency of the singular bending stress...... with increasing depth. The method avoids iterations and enables, for any load and crack length, calculation of the smallest crack depth which would cause instability....
Aerodynamic modelling and optimization of axial fans
Noertoft Soerensen, Dan
1998-01-01
A numerically efficient mathematical model for the aerodynamics of low speed axial fans of the arbitrary vortex flow type has been developed. The model is based on a blade-element principle, whereby the rotor is divided into a number of annular stream tubes. For each of these stream tubes relations for velocity, pressure and radial position are derived from the conservation laws for mass, tangential momentum and energy. The equations are solved using the Newton-Raphson methods, and solutions converged to machine accuracy are found at small computing costs. The model has been validated against published measurements on various fan configurations, comprising two rotor-only fan stages, a counter-rotating fan unit and a stator-rotor stator stage. Comparisons of local and integrated properties show that the computed results agree well with the measurements. Optimizations have been performed to maximize the mean value of fan efficiency in a design interval of flow rates, thus designing a fan which operates well over a range of different flow conditions. The optimization scheme was used to investigate the dependence of maximum efficiency on 1: the number of blades, 2: the width of the design interval and 3: the hub radius. The degree of freedom in the choice of design variable and constraints, combined with the design interval concept, provides a valuable design-tool for axial fans. To further investigate the use of design optimization, a model for the vortex shedding noise from the trailing edge of the blades has been incorporated into the optimization scheme. The noise emission from the blades was minimized in a flow rate design point. Optimizations were performed to investigate the dependence of the noise on 1: the number of blades, 2: a constraint imposed on efficiency and 3: the hub radius. The investigations showed, that a significant reduction of noise could be achieved, at the expense of a small reduction in fan efficiency. (EG) 66 refs.
Prediction of three dimensional maximum isometric neck strength.
Fice, Jason B; Siegmund, Gunter P; Blouin, Jean-Sébastien
2014-09-01
We measured maximum isometric neck strength under combinations of flexion/extension, lateral bending and axial rotation to determine whether neck strength in three dimensions (3D) can be predicted from principal axes strength. This would allow biomechanical modelers to validate their neck models across many directions using only principal axis strength data. Maximum isometric neck moments were measured in 9 male volunteers (29±9 years) for 17 directions. The 3D moments were normalized by the principal axis moments, and compared to unity for all directions tested. Finally, each subject's maximum principal axis moments were used to predict their resultant moment in the off-axis directions. Maximum moments were 30±6 N m in flexion, 32±9 N m in lateral bending, 51±11 N m in extension, and 13±5 N m in axial rotation. The normalized 3D moments were not significantly different from unity (95% confidence interval contained one), except for three directions that combined ipsilateral axial rotation and lateral bending; in these directions the normalized moments exceeded one. Predicted resultant moments compared well to the actual measured values (r2=0.88). Despite exceeding unity, the normalized moments were consistent across subjects to allow prediction of maximum 3D neck strength using principal axes neck strength.
Maximum likely scale estimation
Loog, Marco; Pedersen, Kim Steenstrup; Markussen, Bo
2005-01-01
A maximum likelihood local scale estimation principle is presented. An actual implementation of the estimation principle uses second order moments of multiple measurements at a fixed location in the image. These measurements consist of Gaussian derivatives possibly taken at several scales and/or ...
Golimumab for treatment of axial spondyloarthritis.
Rios Rodriguez, Valeria; Poddubnyy, Denis
2016-02-01
Axial spondyloarthritis comprises two forms: nonradiographic (nonradiographic axial spondyloarthritis) and radiographic (better known as ankylosing spondylitis), which are often considered as two stages of one disease. Historically, all currently available TNF-α inhibitors were first investigated in ankylosing spondylitis and later on in nonradiographic axial spondyloarthritis. This year, EMA has granted golimumab approval for the treatment of active nonradiographic axial spondyloarthritis based on the recently published data from the GO-AHEAD study. This article summarizes recent data on efficacy and safety of golimumab in the treatment of ankylosing spondylitis and nonradiographic axial spondyloarthritis.
ZHANG Neng-hui; WANG Jian-jun; CHENG Chang-jun
2007-01-01
Under the consideration of harmonic fluctuations of initial tension and axially velocity, a nonlinear governing equation for transverse vibration of an axially accelerating string is set up by using the equation of motion for a 3-dimensional deformable body with initial stresses. The Kelvin model is used to describe viscoelastic behaviors of the material. The basis function of the complex-mode Galerkin method for axially accelerating nonlinear strings is constructed by using the modal function of linear moving strings with constant axially transport velocity. By the constructed basis functions, the application of the complex-mode Galerkin method in nonlinear vibration analysis of an axially accelerating viscoelastic string is investigated. Numerical results show that the convergence velocity of the complex-mode Galerkin method is higher than that of the real-mode Galerkin method for a variable coefficient gyroscopic system.
Material characterisation of nanowires with intrinsic stress
Mills, S.; Sader, J. E.; Boland, J. J.
2017-09-01
When fabricating nanowires (NWs) in a doubly-clamped beam configuration it is possible for a residual axial stress to be generated. Here, we show that material characterisation of metal and semiconductor NWs subjected to residual axial stress can be problematic. Benchmark measurements of the Young’s modulus of NWs are performed by sectioning a doubly-clamped NW into two cantilevered wires, eliminating residual axial stress. Use of models for doubly-clamped beams that incorporate the effects of residual stress are found to lead to ambiguity in the extracted Young’s modulus as a function of displacement fit range, even for NWs with no residual stress. This is due to coupling of bending and axial stress effects at small displacements, and the limited displacement range of force curves prior to fracture or plastic deformation. This study highlights the importance of fabricating metal and semiconductor NWs that exhibit little or no residual axial stress for materials characterisation.
Maximum information photoelectron metrology
Hockett, P; Wollenhaupt, M; Baumert, T
2015-01-01
Photoelectron interferograms, manifested in photoelectron angular distributions (PADs), are a high-information, coherent observable. In order to obtain the maximum information from angle-resolved photoionization experiments it is desirable to record the full, 3D, photoelectron momentum distribution. Here we apply tomographic reconstruction techniques to obtain such 3D distributions from multiphoton ionization of potassium atoms, and fully analyse the energy and angular content of the 3D data. The PADs obtained as a function of energy indicate good agreement with previous 2D data and detailed analysis [Hockett et. al., Phys. Rev. Lett. 112, 223001 (2014)] over the main spectral features, but also indicate unexpected symmetry-breaking in certain regions of momentum space, thus revealing additional continuum interferences which cannot otherwise be observed. These observations reflect the presence of additional ionization pathways and, most generally, illustrate the power of maximum information measurements of th...
赵永翔; 王金诺; 高庆
2001-01-01
拓展经典极大似然法到Langer模型，提出了估计三参数、Langer和Basquin三种常用疲劳应力-寿命模型P-S-N曲线及其置信限的统一方法。方法用于处理极大似然法疲劳试验得到的S-N数据。该试验在特别关注的参考载荷试验一组试样，其余试样在不同载荷下试验。以参考载荷试验数据的统计参量为基础，按照每个模型中材料常数协同处于相同概率水平原则，将曲线表示为对数疲劳寿命均值和均方差线的广义形式，至多4个材料常数。曲线中的材料常数按极大似然原理采用数学规划法求出。45＃碳钢缺口试样(kt＝20）对称循环加载试验数据的分析说明了方法的有效性。分析还揭示合理模型有必要通过比较拟合效果、预计误差和应用安全性来确定。三参数模型的拟合效果最好，Langer模型稍差，Basquin模型较差。从拟合效果、预计误差和应用安全性角度，Basquin模型不适于描述该套数据。此外，经典极大似然法估计结果可能因受局部统计参量影响而给出非安全估计，有必要发展改进的可以最大限度减小这种影响的方法。%A unified classical maximum likelihood approach for estimating P-S-N curves of the three commonly used fatigue stress-life relations, namely three parameter, Langer and Basquin, is presented by extrapolating the classical maximum likelihood method to the Langer relation. This approach is applied to deal with the S-N data obtained from a so-called maximum likelihood method-fatigue test. In the test, a group of specimens are tested at a so-called reference load, which is specially taken care of by practice, and residual specimens are individually fatigued at different loads. The approach takes a basis of the local statistical parameters of the logarithms of fatigue lives at the reference load. According to an assumption that the material constants in each relation are concurrently in
Torsional and axial damping properties of the AZ31B-F magnesium alloy
Anes, V.; Lage, Y. E.; Vieira, M.; Maia, N. M. M.; Freitas, M.; Reis, L.
2016-10-01
Damping properties for the AZ31B-F magnesium alloy were evaluated for pure axial and pure shear loading conditions at room temperature. Hysteretic damping results were measured through stress-strain controlled tests. Moreover, the magnesium alloy viscous damping was measured with frequency response functions and free vibration decay, both results were obtained by experiments. The axial and shear damping ratio (ASDR) has been identified and described, specifically for free vibration conditions.
Microstructural and Residual Stress Development due to Inertia Friction Welding in Ti-6246
Attallah, Moataz M.; Preuss, Michael; Boonchareon, Chatri; Steuwer, Axel; Daniels, John E.; Hughes, Darren J.; Dungey, Christopher; Baxter, Gavin J.
2012-09-01
A thorough investigation has been performed to assess the microstructural properties, mechanical properties (hardness and elastic modulus), and residual stress development in Ti-6Al-2Sn-4Zr-6Mo (Ti-6246) inertia friction welds in the as-welded and postweld heat-treated conditions. It was evident that the thermomechanical deformation in the weld region occurred above the β transus, forming dynamically recrystallized β grains and precipitating acicular α within the β grains, which resulted in a localized hardness increase. In the heat-affected zone, a ghost microstructure of the base metal formed because of the absence of sufficient time for diffusion, resulting in Mo segregation in the prior primary α plates. Energy-dispersive synchrotron X-ray diffraction and neutron diffraction were used to assess the residual stress development in the three principal directions. The variation in the unstrained lattice parameters across the weld regions was established by imposing a stress balance on the axial stress component in the radial direction. It was found that the maximum stresses occurred in the hoop direction, with significantly lower stresses present in the radial and axial directions. The maximum tensile hoop stresses were located at ~4 mm from the weld centerline and not at the dynamically recrystallized β-rich weld zone. This was associated with the α → β phase transformation and the subsequent acicular α precipitation within the region surrounding the weld centerline.
Axial Globe Length in Congenital Ptosis.
Takahashi, Yasuhiro; Kang, Hyera; Kakizaki, Hirohiko
2015-01-01
To compare axial globe length between affected and unaffected sides in patients with unilateral congenital ptosis. This prospective observational study included 37 patients (age range: 7 months to 58 years). The axial globe length, margin reflex distance-1 (MRD-1), and refractive power were measured. The axial globe length difference was calculated by subtracting the axial globe length on the unaffected side from that of the affected side. The relationships among axial globe length differences, MRD-1 on the affected sides, and patient ages were analyzed using multiple regression analysis. No significant differences were found in the axial globe length between sides (P = .677). The axial globe length difference was 0.17 ± 0.30 mm (mean ± standard deviation), and two patients (5.4%), aged 32 to 57 years, showed axial globe length more than 0.67 mm longer (corresponding to a refractive power of 2 diopters) on the affected side compared to the unaffected side. The multiple regression model between axial globe length difference, patient age, and MRD-1 on the affected sides was less appropriate (YAGL = 0.003XAGE-0.048XMRD-1 +0.112; r = 0.338; adjusted r2 = 0.062; P = .127). The cylindrical power was greater on the affected side (P = .046), although the spherical power was not different between sides (P = .657). No significant difference was identified in the axial globe length between sides, and only 5% of non-pediatric patients showed an axial globe length more than 0.67 mm longer on the affected side. Congenital ptosis may have little effect on axial globe length elongation, and the risk of axial myopia-induced anisometropic amblyopia may be low in patients with unilateral congenital ptosis. Copyright 2015, SLACK Incorporated.
A velocity parameter for the correlation of axial fan noise
Wright, T.
1982-08-01
An aerodynamic parameter that relates subsonic axial fan noise to the fundamental flow behavior in the blade row of a fan is proposed. The parameter is the peak or maximum blade surface velocity in the rotating reference frame and includes, either explicitly or implicitly, the influence of tip speed, volume flow rate, pressure rise, shaft horsepower and efficiency. Correlation of the noise associated with a very broad range of axial fans yields good agreement and collapse of data when compared to currently used correlation methods. Use of this parameter, rather than those based on overall performance, allows trade-off studies to be made within a given performance requirement so that a minimum noise configuration may be designed or selected.
Maximum Likelihood Associative Memories
Gripon, Vincent; Rabbat, Michael
2013-01-01
Associative memories are structures that store data in such a way that it can later be retrieved given only a part of its content -- a sort-of error/erasure-resilience property. They are used in applications ranging from caches and memory management in CPUs to database engines. In this work we study associative memories built on the maximum likelihood principle. We derive minimum residual error rates when the data stored comes from a uniform binary source. Second, we determine the minimum amo...
Maximum likely scale estimation
Loog, Marco; Pedersen, Kim Steenstrup; Markussen, Bo
2005-01-01
A maximum likelihood local scale estimation principle is presented. An actual implementation of the estimation principle uses second order moments of multiple measurements at a fixed location in the image. These measurements consist of Gaussian derivatives possibly taken at several scales and....../or having different derivative orders. Although the principle is applicable to a wide variety of image models, the main focus here is on the Brownian model and its use for scale selection in natural images. Furthermore, in the examples provided, the simplifying assumption is made that the behavior...... of the measurements is completely characterized by all moments up to second order....
Axial Vector $Z'$ and Anomaly Cancellation
Ismail, Ahmed; Tsao, Kuo-Hsing; Unwin, James
2016-01-01
Whilst the prospect of new $Z'$ gauge bosons with only axial couplings to the Standard Model (SM) fermions is widely discussed, examples of anomaly-free renormalisable models are lacking in the literature. We look to remedy this by constructing several motivated examples. Specifically, we consider axial vectors which couple universally to all SM fermions, as well as those which are generation-specific, leptophilic, and leptophobic. Anomaly cancellation typically requires the presence of new coloured and charged chiral fermions, and we argue that the masses of these new states must generally be comparable to that of the axial vector. Finally, an axial vector mediator could provide a portal between SM and hidden sector states, and we also consider the possibility that the axial vector couples to dark matter. If the dark matter relic density is set due to freeze-out via the axial vector, this strongly constrains the parameter space.
Axial vector Z‧ and anomaly cancellation
Ismail, Ahmed; Keung, Wai-Yee; Tsao, Kuo-Hsing; Unwin, James
2017-05-01
Whilst the prospect of new Z‧ gauge bosons with only axial couplings to the Standard Model (SM) fermions is widely discussed, examples of anomaly-free renormalisable models are lacking in the literature. We look to remedy this by constructing several motivated examples. Specifically, we consider axial vectors which couple universally to all SM fermions, as well as those which are generation-specific, leptophilic, and leptophobic. Anomaly cancellation typically requires the presence of new coloured and charged chiral fermions, and we argue that in a large class of models masses of these new states are expected to be comparable to that of the axial vector. Finally, an axial vector mediator could provide a portal between SM and hidden sector states, and we also consider the possibility that the axial vector couples to dark matter. If the dark matter relic density is set due to freeze-out via the axial vector, this strongly constrains the parameter space.
Diabetes mellitus and the eye: axial length
Huntjens, B.; O’Donnell, C.
2006-01-01
Background and aims: The refractive error of the eye is dependent on its axial length. Refractive error is known to fluctuate significantly in poorly controlled diabetic patients. Recently it has been reported that human eyes fluctuate in axial length during the day. However, this change is not detectable in all subjects, suggesting physiological influences such as diet. The purpose of this study was to investigate fluctuations in axial length and blood glucose levels (BGLs) in diabetic patie...
Instability of meridional axial system in f(R) gravity
Sharif, M.; Yousaf, Z. [University of the Punjab, Department of Mathematics, Lahore (Pakistan)
2015-05-15
We analyze the dynamical instability of a non-static reflection axial stellar structure by taking into account the generalized Euler equation in metric f(R) gravity. Such an equation is obtained by contracting the Bianchi identities of the usual anisotropic and effective stress-energy tensors, which after using a radial perturbation technique gives a modified collapse equation. In the realm of the R + εR{sup n} gravity model, we investigate instability constraints at Newtonian and post-Newtonian approximations. We find that the instability of a meridional axial self-gravitating system depends upon the static profile of the structure coefficients, while f(R) extra curvature terms induce the stability of the evolving celestial body. (orig.)
Laboratory Test Setup for Cyclic Axially Loaded Piles in Sand
Thomassen, Kristina; Ibsen, Lars Bo; Andersen, Lars Vabbersgaard
2017-01-01
conditions for all tests. For verifications purposes six static tension tests conducted at three different vertical effective stress levels of 0, 35 and 70 kPa. The load-displacement curves showed that the test setup provides repeatable test results. A preliminary comparison between the unit shaft friction......This paper presents a comprehensive description and the considerations regarding the design of a new laboratory test setup for testing cyclic axially loaded piles in sand. The test setup aims at analysing the effect of axial one-way cyclic loading on pile capacity and accumulated displacements....... Another aim was to test a large diameter pile segment with dimensions resembling full-scale piles to model the interface properties between pile and sand correctly. The pile segment was an open-ended steel pipe pile with a diameter of 0.5 m and a length of 1 m. The sand conditions resembled the dense sand...
System Study for Axial Vane Engine Technology
Badley, Patrick R.; Smith, Michael R.; Gould, Cedric O.
2008-01-01
The purpose of this engine feasibility study was to determine the benefits that can be achieved by incorporating positive displacement axial vane compression and expansion stages into high bypass turbofan engines. These positive-displacement stages would replace some or all of the conventional compressor and turbine stages in the turbine engine, but not the fan. The study considered combustion occurring internal to an axial vane component (i.e., Diesel engine replacing the standard turbine engine combustor, burner, and turbine); and external continuous flow combustion with an axial vane compressor and an axial vane turbine replacing conventional compressor and turbine systems.
F. TopsÃƒÂ¸e
2001-09-01
Full Text Available Abstract: In its modern formulation, the Maximum Entropy Principle was promoted by E.T. Jaynes, starting in the mid-fifties. The principle dictates that one should look for a distribution, consistent with available information, which maximizes the entropy. However, this principle focuses only on distributions and it appears advantageous to bring information theoretical thinking more prominently into play by also focusing on the "observer" and on coding. This view was brought forward by the second named author in the late seventies and is the view we will follow-up on here. It leads to the consideration of a certain game, the Code Length Game and, via standard game theoretical thinking, to a principle of Game Theoretical Equilibrium. This principle is more basic than the Maximum Entropy Principle in the sense that the search for one type of optimal strategies in the Code Length Game translates directly into the search for distributions with maximum entropy. In the present paper we offer a self-contained and comprehensive treatment of fundamentals of both principles mentioned, based on a study of the Code Length Game. Though new concepts and results are presented, the reading should be instructional and accessible to a rather wide audience, at least if certain mathematical details are left aside at a rst reading. The most frequently studied instance of entropy maximization pertains to the Mean Energy Model which involves a moment constraint related to a given function, here taken to represent "energy". This type of application is very well known from the literature with hundreds of applications pertaining to several different elds and will also here serve as important illustration of the theory. But our approach reaches further, especially regarding the study of continuity properties of the entropy function, and this leads to new results which allow a discussion of models with so-called entropy loss. These results have tempted us to speculate over
Unsteady Flows in Axial Turbomachines
Marble, F. E.; Rannie, W. D.
1957-01-01
Of the various unsteady flows that occur in axial turbomachines certain asymmetric disturbances, of wave length large in comparison with blade spacing, have become understood to a certain extent. These disturbances divide themselves into two categories: self-induced oscillations and force disturbances. A special type of propagating stall appears as a self-induced disturbance; an asymmetric velocity profile introduced at the compressor inlet constitutes a forced disturbance. Both phenomena have been treated from a unified theoretical point of view in which the asymmetric disturbances are linearized and the blade characteristics are assumed quasi-steady. Experimental results are in essential agreement with this theory wherever the limitations of the theory are satisfied. For the self-induced disturbances and the more interesting examples of the forced disturbances, the dominant blade characteristic is the dependence of total pressure loss, rather than the turning angle, upon the local blade inlet angle.
Peter Svenonius
2007-01-01
Full Text Available Many languages have specialized locative words or morphemes translating roughly into words like ‘front,’ ‘back,’ ‘top,’ ‘bottom,’ ‘side,’ and so on. Often, these words are used instead of more specialized adpositions to express spatial meanings corresponding to ‘behind,’ ‘above,’ and so on. I argue, on the basis of a cross-linguistic survey of such expressions, that in many cases they motivate a syntactic category which is distinct from both N and P, which I call AxPart for ‘Axial Part’; I show how the category relates to the words which instantiate it, and how the meaning of the construction is derived from the combination of P[lace] elements, AxParts, and the lexical material which expresses them.
Regularized maximum correntropy machine
Wang, Jim Jing-Yan
2015-02-12
In this paper we investigate the usage of regularized correntropy framework for learning of classifiers from noisy labels. The class label predictors learned by minimizing transitional loss functions are sensitive to the noisy and outlying labels of training samples, because the transitional loss functions are equally applied to all the samples. To solve this problem, we propose to learn the class label predictors by maximizing the correntropy between the predicted labels and the true labels of the training samples, under the regularized Maximum Correntropy Criteria (MCC) framework. Moreover, we regularize the predictor parameter to control the complexity of the predictor. The learning problem is formulated by an objective function considering the parameter regularization and MCC simultaneously. By optimizing the objective function alternately, we develop a novel predictor learning algorithm. The experiments on two challenging pattern classification tasks show that it significantly outperforms the machines with transitional loss functions.
Shihab A. Romeed
2012-01-01
Full Text Available Non-carious cervical tooth lesions for many decades were attributed to the effects of abrasion and erosion mainly through toothbrush trauma, abrasive toothpaste, and erosive acids. However, though the above may be involved, more recently a biomechanical theory for the formation of these lesions has arisen, and the term abfraction was coined. The aim of this study was to investigate the biomechanics of abfraction lesions in upper canine teeth under axial and lateral loading conditions using a three-dimensional finite element analysis. An extracted human upper canine tooth was scanned by μCT machine (Skyscan, Belgium. These μCT scans were segmented, reconstructed, and meshed using ScanIP (Simpleware, Exeter, UK to create a three-dimensional finite element model. A 100 N load was applied axially at the incisal edge and laterally at 45° midpalatally to the long axis of the canine tooth. Separately, 200 N axial and non-axial loads were applied simultaneously to the tooth. It was found that stresses were concentrated at the CEJ in all scenarios. Lateral loading produced maximum stresses greater than axial loading, and pulp tissues, however, experienced minimum levels of stresses. This study has contributed towards the understanding of the aetiology of non-carious cervical lesions which is a key in their clinical management.
Thermal characterization of phacoemulsification probes operated in axial and torsional modes.
Zacharias, Jaime
2015-01-01
To analyze temperature increases and identify potential sources of heat generated when sleeved and sleeveless phacoemulsification probes were operated in axial and torsional modes using the Infiniti Vision System with the Ozil torsional handpiece. Phacodynamics Laboratory, Pasteur Ophthalmic Clinic, Santiago, Chile. Experimental study. Two computer-controlled thermal transfer systems were developed to evaluate the contribution of internal metal stress and tip-to-sleeve friction on heat generation during phacoemulsification using axial and torsional ultrasound modalities. Both systems incorporated infrared thermal imaging and used a black-body film to accurately capture temperature measurements. Axial mode was consistently associated with greater temperature increases than torsional mode whether tips were operated with or without sleeves. In tests involving bare tips, axial mode and torsional mode peaked at 51.7°C and 34.2°C, respectively. In an example using sleeved tips in which a 30.0 g load was applied for 1 second, temperatures for axial mode reached 45°C and for torsional mode, 38°C. Friction between the sleeved probe and the incisional wall contributed more significantly to the temperature increase than internal metal stress regardless of the mode used. In all experiments, the temperature increase observed with axial mode was greater than that observed with torsional mode, even when conditions such as power or amplitude and flow rate were varied. Tip-to-sleeve friction was a more dominant source of phaco probe heating than internal metal stress. The temperature increase due to internal metal stress was greater with axial mode than with torsional mode. Dr. Zacharias received research funding from Alcon Laboratories, Inc., to conduct this study. He has no financial or proprietary interest in any material or method mentioned. Copyright © 2015 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.
Equalized near maximum likelihood detector
2012-01-01
This paper presents new detector that is used to mitigate intersymbol interference introduced by bandlimited channels. This detector is named equalized near maximum likelihood detector which combines nonlinear equalizer and near maximum likelihood detector. Simulation results show that the performance of equalized near maximum likelihood detector is better than the performance of nonlinear equalizer but worse than near maximum likelihood detector.
Cheeseman, Peter; Stutz, John
2005-01-01
A long standing mystery in using Maximum Entropy (MaxEnt) is how to deal with constraints whose values are uncertain. This situation arises when constraint values are estimated from data, because of finite sample sizes. One approach to this problem, advocated by E.T. Jaynes [1], is to ignore this uncertainty, and treat the empirically observed values as exact. We refer to this as the classic MaxEnt approach. Classic MaxEnt gives point probabilities (subject to the given constraints), rather than probability densities. We develop an alternative approach that assumes that the uncertain constraint values are represented by a probability density {e.g: a Gaussian), and this uncertainty yields a MaxEnt posterior probability density. That is, the classic MaxEnt point probabilities are regarded as a multidimensional function of the given constraint values, and uncertainty on these values is transmitted through the MaxEnt function to give uncertainty over the MaXEnt probabilities. We illustrate this approach by explicitly calculating the generalized MaxEnt density for a simple but common case, then show how this can be extended numerically to the general case. This paper expands the generalized MaxEnt concept introduced in a previous paper [3].
Health and imaging outcomes in axial spondyloarthritis
Machado, P.M.
2016-01-01
This thesis focuses on the assessment and monitoring of health and imaging outcomes in axial spondyloarthritis (SpA) and the relationship between these outcomes. Four major contributions to the understanding and management of axial SpA were made: 1) the improvement and facilitation of the assessment
Universal Axial Fluctuations in Optical Tweezers
Ribezzi-Crivellari, Marco; Ritort, Felix
2015-01-01
Optical tweezers allow the measurement of fluctuations at the nano-scale, in particular fluctuations in the end-to-end distance in single molecules. Fluctuation spectra can yield valuable information, but they can easily be contaminated by instrumental effects. We identify axial fluctuations, i.e. fluctuations of the trapped beads in the direction of light propagation, as one of these instrumental effects. Remarkably, axial fluctuations occur on a characteristic timescale similar to that of conformational (folding) transitions, which may lead to misinterpretation of the experimental results. We show that a precise measurement of the effect of force on both axial and conformational fluctuations is crucial to disentangle them. Our results on axial fluctuations are captured by a simple and general formula valid for all optical tweezers setups and provide experimentalists with a general strategy to distinguish axial fluctuations from conformational transitions.
Novel Integration Radial and Axial Magnetic Bearing
Blumenstock, Kenneth; Brown, Gary
2000-01-01
Typically, fully active magnetically suspended systems require one axial and two radial magnetic bearings. Combining radial and axial functions into a single device allows for more compact and elegant packaging. Furthermore, in the case of high-speed devices such as energy storage flywheels, it is beneficial to minimize shaft length to keep rotor mode frequencies as high as possible. Attempts have been made to combine radial and axial functionality, but with certain drawbacks. One approach requires magnetic control flux to flow through a bias magnet reducing control effectiveness, thus resulting in increased resistive losses. This approach also requires axial force producing magnetic flux to flow in a direction into the rotor laminate that is undesirable for minimizing eddy-current losses resulting in rotational losses. Another approach applies a conical rotor shape to what otherwise would be a radial heteropolar magnetic bearing configuration. However, positional non-linear effects are introduced with this scheme and the same windings are used for bias, radial, and axial control adding complexity to the controller and electronics. For this approach, the amount of axial capability must be limited. It would be desirable for an integrated radial and axial magnetic bearing to have the following characteristics; separate inputs for radial and axial control for electronics and control simplicity, all magnetic control fluxes should only flow through their respective air gaps and should not flow through any bias magnets for minimal resistive losses, be of a homopolar design to minimize rotational losses, position related non-linear effects should be minimized, and dependent upon the design parameters, be able to achieve any radial/axial force or power ratio as desired. The integrated radial and axial magnetic bearing described in this paper exhibits all these characteristics. Magnetic circuit design, design equations, and magnetic field modeling results will be presented.
Novel Integrated Radial and Axial Magnetic Bearing
Blumenstock, Kenneth A.; Brown, Gary L.; Powers, Edward I. (Technical Monitor)
2000-01-01
Typically, fully active magnetically suspended systems require one axial and two radial magnetic bearings. Combining radial and axial functions into a single device allows for more compact and elegant packaging. Furthermore, in the case of high-speed devices such as energy storage flywheels, it is beneficial to minimize shaft length to keep rotor mode frequencies as high as possible. Attempts have been made to combine radial and axial functionality, but with certain drawbacks. One approach requires magnetic control flux to flow through a bias magnet reducing control effectiveness, thus resulting in increased resistive losses. This approach also requires axial force producing magnetic flux to flow in a direction into the rotor laminate that is undesirable for minimizing eddy-current losses resulting in rotational losses. Another approach applies a conical rotor shape to what otherwise would be a radial heteropolar magnetic bearing configuration. However, positional non-linear effects are introduced with this scheme and the same windings are used for bias, radial, and axial control adding complexity to the controller and electronics. For this approach, the amount of axial capability must be limited. It would be desirable for an integrated radial and axial magnetic bearing to have the following characteristics, separate inputs for radial and axial control for electronics and control simplicity, all magnetic control fluxes should only flow through their respective air gaps and should not flow through any bias magnets for minimal resistive losses, be of a homopolar design to minimize rotational losses, position related non-linear effects should be minimized, and dependent upon the design parameters, be able to achieve any radial/axial force or power ratio as desired. The integrated radial and axial magnetic bearing described in this paper exhibits all these characteristics. Magnetic circuit design, design equations, and analysis results will be presented.
Transverse Vibration of Axially Moving Functionally Graded Materials Based on Timoshenko Beam Theory
Suihan Sui
2015-01-01
Full Text Available The transverse free vibration of an axially moving beam made of functionally graded materials (FGM is investigated using a Timoshenko beam theory. Natural frequencies, vibration modes, and critical speeds of such axially moving systems are determined and discussed in detail. The material properties are assumed to vary continuously through the thickness of the beam according to a power law distribution. Hamilton’s principle is employed to derive the governing equation and a complex mode approach is utilized to obtain the transverse dynamical behaviors including the vibration modes and natural frequencies. Effects of the axially moving speed and the power-law exponent on the dynamic responses are examined. Some numerical examples are presented to reveal the differences of natural frequencies for Timoshenko beam model and Euler beam model. Moreover, the critical speed is determined numerically to indicate its variation with respect to the power-law exponent, axial initial stress, and length to thickness ratio.
Behavior of Unbonded Flexible Risers Subject to Axial Tension
任少飞; 唐文勇; 郭晋挺
2014-01-01
Owing to nonlinear contact problems with slip and friction, a lot of limiting assumptions are made when developing analytical models to simulate the behavior of an unbonded flexible riser. Meanwhile, in order to avoid convergence problems and excessive calculating time associated with running the detailed finite element (FE) model of an unbonded flexible riser, interlocked carcass and zeta layers with complicated cross section shapes are replaced by simple geometrical shapes (e.g. hollow cylindrical shell) with equivalent orthotropic materials. But the simplified model does not imply the stresses equivalence of these two layers. To solve these problems, based on ABAQUS/Explicit, a numerical method that is suitable for the detailed FE model is proposed. In consideration of interaction among all component layers, the axial stiffness of an eight-layer unbonded flexible riser subjected to axial tension is predicted. Compared with analytical and experimental results, it is shown that the proposed numerical method not only has high accuracy but also can substantially reduce the calculating time. In addition, the impact of the lay angle of helical tendons on axial stiffness is discussed.
Spahn, G; Wittig, R
2003-01-01
Explanations concerning the physical properties of hyaline cartilage are different. It was the intention of this study to determine the material parameters of hyaline cartilage under axial load (elasticity, plasticity, elasticity and module pressure stress to break). Specimens from the medial femoral condyle (chondro-cortical ships) from adult female domestic pigs (n=28) were used for the experiments. The specimens were completely embedded in plaster to minimize shearing. Axial load was carried out by an universal mechanical testing machine (Zwick Z2.5/TS1S, Ulm, Germany) to determine elastic and plastic deformation and pressure stress to break. Axial load up to 5 MPa produces an almost elastic deformation, an increasing axial load results in a plastic deformation. In the range of 3 to 5 MPa the principle of Hooke is valid. The elasticity module amounted to 39.2 +/- 11.9 N/mm(2), determined under 3.8 MPa axial load. An axial load of 25.8 +/- 5.2 MPa (sigma max ) causes a break of cartilage. A strong correlation between break resistance and thickness of the chondral slice (r=0.71; p .05) was observed. The low module of chondral elasticity characterizes this tissue as "soft". Moderate axial load causes an ideal elastic, higher axial load a plastic deformation. The medium pressure to break to amounted 25.8 MPa. The medium pressure to break of 25.8 MPa is comparable with the forces produced by an unrestrained limited downfall from a height of 4.3 m. It must be concluded that isolated chondral fractures are rare consequences of a trauma as long as accompanying ligamentous or osseous damages are not found.
An Assessment of Cumulative Axial and Torsional Fatigue in a Cobalt-Base Superalloy
Kalluri, Sreeramesh; Bonacuse, Peter J.
2010-01-01
is discussed. Possible reasons for the observed differences between the computed and observed summations of cycle fractions are rationalized in terms of the observed ever lutions of cyclic axial and shear stress ranges in the cumulative fatigue tests.
The effect of suspension concentration on the buildup evolution in a HGMF-axial magnetic filter
Murariu, V.; Rezlescu, N.; Rotariu, O.; Badescu, V.
1998-01-01
In this work the influence of solid particles concentration from suspension on the buildup evolution for a single wire from a magnetic filter working in axial configuration is presented. The buildup differential equations are solved and the surface contour of the buildup at different moments is obtained. It is evidenced the existence of a suspension concentration for which the radial deposit extension is maximum.
Axial force measurement for esophageal function testing
Flemming H Gravesen; Peter Funch-Jensen; Hans Gregersen; Asbjφrn Mohr Drewes
2009-01-01
The esophagus serves to transport food and fluid from the pharynx to the stomach. Manometry has been the "golden standard" for the diagnosis of esophageal motility diseases for many decades. Hence, esophageal function is normally evaluated by means of manometry even though it reflects the squeeze force (force in radial direction) whereas the bolus moves along the length of esophagus in a distal direction. Force measurements in the longitudinal (axial) direction provide a more direct measure of esophageal transport function. The technique used to record axial force has developed from external force transducers over in-vivo strain gauges of various sizes to electrical impedance based measurements. The amplitude and duration of the axial force has been shown to be as reliable as manometry. Normal, as well as abnormal, manometric recordings occur with normal bolus transit, which have been documented using imaging modalities such as radiography and scintigraphy. This inconsistency using manometry has also been documented by axial force recordings. This underlines the lack of information when diagnostics are based on manometry alone. Increasing the volume of a bag mounted on a probe with combined axial force and manometry recordings showed that axial force amplitude increased by 130% in contrast to an increase of 30% using manometry. Using axial force in combination with manometry provides a more complete picture of esophageal motility, and the current paper outlines the advantages of using this method.
Axial force measurement for esophageal function testing.
Gravesen, Flemming H; Funch-Jensen, Peter; Gregersen, Hans; Drewes, Asbjørn Mohr
2009-01-14
The esophagus serves to transport food and fluid from the pharynx to the stomach. Manometry has been the "golden standard" for the diagnosis of esophageal motility diseases for many decades. Hence, esophageal function is normally evaluated by means of manometry even though it reflects the squeeze force (force in radial direction) whereas the bolus moves along the length of esophagus in a distal direction. Force measurements in the longitudinal (axial) direction provide a more direct measure of esophageal transport function. The technique used to record axial force has developed from external force transducers over in-vivo strain gauges of various sizes to electrical impedance based measurements. The amplitude and duration of the axial force has been shown to be as reliable as manometry. Normal, as well as abnormal, manometric recordings occur with normal bolus transit, which have been documented using imaging modalities such as radiography and scintigraphy. This inconsistency using manometry has also been documented by axial force recordings. This underlines the lack of information when diagnostics are based on manometry alone. Increasing the volume of a bag mounted on a probe with combined axial force and manometry recordings showed that axial force amplitude increased by 130% in contrast to an increase of 30% using manometry. Using axial force in combination with manometry provides a more complete picture of esophageal motility, and the current paper outlines the advantages of using this method.
New Anomaly of the Axial-Vector Current
HE Han-Xin
2001-01-01
By computing the axial-vector current operator equation, we find the anomalous axial-vector curl equation besides the well-known anomalous axial-vector divergence equation (the Adler-Bell-Jackiw anomaly) and discuss its implication.``
Numerical investigation on the axial interaction between buried district heating pipes and soil
Weidlich, Ingo; Achmus, Martin
2008-09-15
Pipe-soil interaction has to be taken into account in the design of district heating (DH) pipes. The investigation presented here focuses on the effect of the reduction of axial friction forces due to cyclic axial displacements and the corresponding stress redistribution. Calculations with a three-dimensional finite element model were carried out in which a standard situation of a buried DH pipe was studied. A significant reduction of friction with cyclic axial displacements was obtained, although no temperature loading and thus no radial expansion of the pipe was considered. The reason for the friction force decrease is a densification of the soil beneath the pipe, which leads to a decrease of the normal stress acting between pipe and soil.
Performance Analysis of CFRP Composite Strips Confined RC Columns under Axial Compression
J. Raja Murugadoss
2015-01-01
Full Text Available In an attempt to mitigate the high cost of FRP composite strengthening, an experimental investigation was carried out that sought to achieve efficient and most favorable FRP strengthening using CFRP composite strips. 50 mm wide CFRP composite strips were used in two different spacings (20 mm and 40 mm to confine columns. The test results of the column confined with smaller spacing (20 mm showed significant restraint of axial deformation of the column and enhanced the strength capacity to a maximum of 99.20% compared to that of reference column. In contrast, the column confined by strips with larger spacing (40 mm failed by crushing of concrete alone, which occurred even before the CFRP strips reached their ultimate strain. In addition, the embodied energy that exists in the CFRP strips could not be utilized effectively. The stress and strength enhancement ratio of this present study was compared with the previous research that has been conducted on columns confined with full wrapping. From the obtained results, it is recommended that CFRP strips with a spacing of 20 mm be used to improve the strength capacity of the RC column; in addition, this wrapping technique provides economic benefits compared to a column confined with full wrapping.
Numerical simulation of stress and deformation of in-service welding onto gas pipeline
Chen Yuhua; Wang Yong; Han Bin; Wang Zhengfang
2006-01-01
SYSWELD was used to simulate in-service welding process of gas pipeline of X70 pipeline steel. Welding thermal cycle, stress and deformation of in-service welded joint were studied. The results show that peak temperature of coarse grain heat-affected zone (CGHAZ) of in-service welding onto gas pipeline is the same with routine welding, but t8/5 ,t8/3 and t8/1 decrease at certain degree. For the zone near welded seam, axial stress and hoop stress in the inner pipe wall are compressive stress when welding source passes through the cross-section that is studied, but residual axial stress and residual hoop stress after welded are all tensile stress. Transient deformation and residual deformation are all convex deformation compared with the original pipe diameter size. Deformation achieves maximum when welding thermal source passes through the cross-section that is studied and then decreases during the cooling process after welding.
Axial force measurement for esophageal function testing
Gravesen, Flemming Holbæk; Funch-Jensen, Peter; Gregersen, Hans
2009-01-01
force transducers over in-vivo strain gauges of various sizes to electrical impedance based measurements. The amplitude and duration of the axial force has been shown to be as reliable as manometry. Normal, as well as abnormal, manometric recordings occur with normal bolus transit, which have been...... force (force in radial direction) whereas the bolus moves along the length of esophagus in a distal direction. Force measurements in the longitudinal (axial) direction provide a more direct measure of esophageal transport function. The technique used to record axial force has developed from external...... documented using imaging modalities such as radiography and scintigraphy. This inconsistency using manometry has also been documented by axial force recordings. This underlines the lack of information when diagnostics are based on manometry alone. Increasing the volume of a bag mounted on a probe...
Axial Super-resolution Evanescent Wave Tomography
Pendharker, Sarang; Newman, Ward; Ogg, Stephen; Nazemifard, Neda; Jacob, Zubin
2016-01-01
Optical tomographic reconstruction of a 3D nanoscale specimen is hindered by the axial diffraction limit, which is 2-3 times worse than the focal plane resolution. We propose and experimentally demonstrate an axial super-resolution evanescent wave tomography (AxSET) method that enables the use of regular evanescent wave microscopes like Total Internal Reflection Fluorescence Microscope (TIRF) beyond surface imaging, and achieve tomographic reconstruction with axial super-resolution. Our proposed method based on Fourier reconstruction achieves axial super-resolution by extracting information from multiple sets of three-dimensional fluorescence images when the sample is illuminated by an evanescent wave. We propose a procedure to extract super-resolution features from the incremental penetration of an evanescent wave and support our theory by 1D (along the optical axis) and 3D simulations. We validate our claims by experimentally demonstrating tomographic reconstruction of microtubules in HeLa cells with an axi...
How to diagnose axial spondyloarthritis early
Rudwaleit, M.; van der Heijde, D.; Khan, M.; Braun, J.; Sieper, J.
2004-01-01
Background: Chronic low back pain (LBP), the leading symptom of ankylosing spondylitis (AS) and undifferentiated axial spondyloarthritis (SpA), precedes the development of radiographic sacroiliitis, sometimes by many years.
Axial thermal rotation of slender rods.
Li, Dichuan; Fakhri, Nikta; Pasquali, Matteo; Biswal, Sibani Lisa
2011-05-06
Axial rotational diffusion of rodlike polymers is important in processes such as microtubule filament sliding and flagella beating. By imaging the motion of small kinks along the backbone of chains of DNA-linked colloids, we produce a direct and systematic measurement of axial rotational diffusivity of rods both in bulk solution and near a wall. The measured diffusivities decrease linearly with the chain length, irrespective of the distance from a wall, in agreement with slender-body hydrodynamics theory. Moreover, the presence of small kinks does not affect the chain's axial diffusivity. Our system and measurements provide insights into fundamental axial diffusion processes of slender objects, which encompass a wide range of entities including biological filaments and linear polymer chains.
Nonperturbative Aspects of Axial Vector Vertex
ZONG Hong-Shi; CHEN Xiang-Song; WANG Fan; CHANG Chao-Hsi; ZHAO En-Guang
2002-01-01
It is shown how the axial vector current of current quarks is related to that of constituent quarks within the framework of the global color symmetry model.Gluon dressing of the axial vector vertex and the quark self-energy functions are described by the inhomogeneous Bethe-Salpeter equation in the ladder approximation and the Schwinger Dyson equation in the rainbow approximation,respectively.
Numerical simulation of axial flow compressors.
Jesuino Takachi Tomita
2002-01-01
This work deals with the numerical simulation of axial flow compressors, from design to performance prediction. The stage performance prediction uses the meanline flow properties. Stage-stacking is used to analyse a multi-stage compressor. A computer program, written in FORTRAN, was developed and is able to design an axial flow compressor given air mass flow, total pressure ratio, overall efficiency and design speed. All geometrical data relevant to the compressor performance prediction is ca...
Failure processes in embedded monolayer graphene under axial compression.
Androulidakis, Charalampos; Koukaras, Emmanuel N; Frank, Otakar; Tsoukleri, Georgia; Sfyris, Dimitris; Parthenios, John; Pugno, Nicola; Papagelis, Konstantinos; Novoselov, Kostya S; Galiotis, Costas
2014-06-12
Exfoliated monolayer graphene flakes were embedded in a polymer matrix and loaded under axial compression. By monitoring the shifts of the 2D Raman phonons of rectangular flakes of various sizes under load, the critical strain to failure was determined. Prior to loading care was taken for the examined area of the flake to be free of residual stresses. The critical strain values for first failure were found to be independent of flake size at a mean value of -0.60% corresponding to a yield stress up to -6 GPa. By combining Euler mechanics with a Winkler approach, we show that unlike buckling in air, the presence of the polymer constraint results in graphene buckling at a fixed value of strain with an estimated wrinkle wavelength of the order of 1-2 nm. These results were compared with DFT computations performed on analogue coronene/PMMA oligomers and a reasonable agreement was obtained.
Wave propagation in axially moving periodic strings
Sorokin, Vladislav S.; Thomsen, Jon Juel
2017-04-01
The paper deals with analytically studying transverse waves propagation in an axially moving string with periodically modulated cross section. The structure effectively models various relevant technological systems, e.g. belts, thread lines, band saws, etc., and, in particular, roller chain drives for diesel engines by capturing both their spatial periodicity and axial motion. The Method of Varying Amplitudes is employed in the analysis. It is shown that the compound wave traveling in the axially moving periodic string comprises many components with different frequencies and wavenumbers. This is in contrast to non-moving periodic structures, for which all components of the corresponding compound wave feature the same frequency. Due to this "multi-frequency" character of the wave motion, the conventional notion of frequency band-gaps appears to be not applicable for the moving periodic strings. Thus, for such structures, by frequency band-gaps it is proposed to understand frequency ranges in which the primary component of the compound wave attenuates. Such frequency band-gaps can be present for a moving periodic string, but only if its axial velocity is lower than the transverse wave speed, and, the higher the axial velocity, the narrower the frequency band-gaps. The revealed effects could be of potential importance for applications, e.g. they indicate that due to spatial inhomogeneity, oscillations of axially moving periodic chains always involve a multitude of frequencies.
An Unbroken Axial Vector Current Conservation Law
Sharafiddinov, Rasulkhozha S
2015-01-01
The mass, energy and momentum of the neutrino of a true flavor have an axial-vector nature. As a consequence, the left-handed truly neutral neutrino in an axial-vector field of emission can be converted into a right-handed one and vice versa. This predicts the unidenticality of masses, energies and momenta of neutrinos of the different components. Recognizing such a difference in masses, energies, momenta and accepting that the left-handed axial-vector neutrino and the right-handed antineutrino of true neutrality refer to long-lived C-odd leptons, and the right-handed truly neutral neutrino and the left-handed axial-vector antineutrino are of short-lived fermions of C-oddity, we would write a new CP-even Dirac equation taking into account the flavor symmetrical axial-vector mass, energy and momentum matrices. Their presence explains the spontaneous mirror symmetry violation, confirming that an axial-vector current conservation law has never violated. They reflect the availability of a mirror Minkowski space i...
Parallax error in long-axial field-of-view PET scanners—a simulation study
Schmall, Jeffrey P.; Karp, Joel S.; Werner, Matt; Surti, Suleman
2016-07-01
There is a growing interest in the design and construction of a PET scanner with a very long axial extent. One critical design challenge is the impact of the long axial extent on the scanner spatial resolution properties. In this work, we characterize the effect of parallax error in PET system designs having an axial field-of-view (FOV) of 198 cm (total-body PET scanner) using fully-3D Monte Carlo simulations. Two different scintillation materials were studied: LSO and LaBr3. The crystal size in both cases was 4 × 4 × 20 mm3. Several different depth-of-interaction (DOI) encoding techniques were investigated to characterize the improvement in spatial resolution when using a DOI capable detector. To measure spatial resolution we simulated point sources in a warm background in the center of the imaging FOV, where the effects of axial parallax are largest, and at several positions radially offset from the center. Using a line-of-response based ordered-subset expectation maximization reconstruction algorithm we found that the axial resolution in an LSO scanner degrades from 4.8 mm to 5.7 mm (full width at half max) at the center of the imaging FOV when extending the axial acceptance angle (α) from ±12° (corresponding to an axial FOV of 18 cm) to the maximum of ±67°—a similar result was obtained with LaBr3, in which the axial resolution degraded from 5.3 mm to 6.1 mm. For comparison we also measured the degradation due to radial parallax error in the transverse imaging FOV; the transverse resolution, averaging radial and tangential directions, of an LSO scanner was degraded from 4.9 mm to 7.7 mm, for a measurement at the center of the scanner compared to a measurement with a radial offset of 23 cm. Simulations of a DOI detector design improved the spatial resolution in all dimensions. The axial resolution in the LSO-based scanner, with α = ± 67°, was improved from 5.7 mm to 5.0 mm by
Analyses of axial, lateral and circumferential deformations of rock specimen in triaxial compression
WANG Xue-bin
2008-01-01
The axial, lateral and circumferential strains were analyzed for a rock specimen subjected to shear failure in the form of a shear band bisecting the specimen in triaxial compression. Plastic deformation of the specimen stemmed from shear strain localization initiated at the peak shear stress. Beyond the onset of strain localization, the axial, lateral and circumferential strains were decomposed into two parts, respectively. One is the elas-tic strain described by general Hooke's law. The other is attributable to the plastic shear slips along shear band with a certain thickness dependent on the internal length of rock.The post-peak circumferential strain-axial strain curve of longer specimen is steeper than that of shorter specimen, as is consistent with the previous experiments. In elastic stage,the circumferential strain-axial strain curve exhibits nonlinear characteristic, as is in agreement with the previous experiment since confining pressure is loaded progressively until a certain value is reached. When the confining pressure is loaded completely, the circumferential strain-axial strain curve is linear in elastic and strain-softening stages. The predicted circumferential strain-axial strain curve in elastic and strain- softening stages agrees with the previous experiment.
Atlanto-axial subluxation after pyogenic spondylitis of the atlanto-occipital joint.
Tsunoda, Kazuhiko; Iizuka, Haku; Sorimachi, Yasunori; Ara, Tsuyoshi; Nishinome, Masahiro; Takechi, Yasuhiko; Takagishi, Kenji
2011-07-01
This report presents a case of atlanto-axial subluxation after treatment of pyogenic spondylitis of the atlanto-occipital joint. A 60-year-old male had 1-month history of neck pain with fever. Magnetic resonance imaging showed inflammation around the odontoid process. Intravenous antibiotic therapy was administrated immediately. After 6 weeks, CRP had returned almost to normal. After 4 months, laboratory data was still normal, but the patient experienced increasing neck pain. Lateral cervical radiography in the neutral position showed instability between C1 and C2. Computed tomography showed a bony union of the atlanto-occipital joint and severe destruction of the atlanto-axial joint on the left side. Transarticular screw fixation for the atlanto-axial joint was performed. A lateral cervical radiograph in the neutral position after surgery showed a solid bony union. Neck pain improved following surgery. We speculate that spondylitis of the atlanto-occipital joint induced a loosening of the transverse ligament and articulation of the atlanto-axial joint. A bony fusion of the atlanto-occipital joint after antibiotic treatment resolved the pyogenic inflammation concentrated stress to the damaged atlanto-axial joint, resulting in further damage. The atlanto-axial instability was finally managed by the insertion of a transarticular screw.
Overall bolt stress optimization
Pedersen, Niels Leergaard
2013-01-01
The state of stress in bolts and nuts with International Organization for Standardization metric thread design is examined and optimized. The assumed failure mode is fatigue, so the applied preload and the load amplitude together with the stress concentrations define the connection strength....... Maximum stress in the bolt is found at the fillet under the head, at the thread start, or at the thread root. To minimize the stress concentration, shape optimization is applied. Nut shape optimization also has a positive effect on the maximum stress. The optimization results show that designing a nut......, which results in a more evenly distribution of load along the engaged thread, has a limited influence on the maximum stress due to the stress concentration at the first thread root. To further reduce the maximum stress, the transition from bolt shank to the thread must be optimized. Stress reduction...
Wei Li
2016-10-01
Full Text Available The interior defect-induced fracture of surface-hardened metallic materials in the long life region has become a key issue on engineering design. In the present study, the axial loading test with fully reversed condition was performed to examine the fatigue property of a surface-carburized low alloy gear steel in the long life region. Results show that this steel represents the duplex S-N (stress-number of cycles characteristics without conventional fatigue limit related to 107 cycles. Fatigue cracks are all originated from the interior inclusions in the matrix region due to the inhabitation effect of carburized layer. The inclusion induced fracture with fisheye occurs in the short life region below 5 × 105 cycles, whereas the inclusion induced fracture with fine granular area (FGA and fisheye occurs in the long life region beyond 106 cycles. The stress intensity factor range at the front of FGA can be regarded as the threshold value controlling stable growth of interior long crack. The evaluated maximum inclusion size in the effective damage volume of specimen is about 27.29 μm. Considering the size relationships between fisheye and FGA, and inclusion, the developed life prediction method involving crack growth can be acceptable on the basis of the good agreement between the predicted and experimental results.
Li, Wei; Deng, Hailong; Liu, Pengfei
2016-10-18
The interior defect-induced fracture of surface-hardened metallic materials in the long life region has become a key issue on engineering design. In the present study, the axial loading test with fully reversed condition was performed to examine the fatigue property of a surface-carburized low alloy gear steel in the long life region. Results show that this steel represents the duplex S-N (stress-number of cycles) characteristics without conventional fatigue limit related to 10⁷ cycles. Fatigue cracks are all originated from the interior inclusions in the matrix region due to the inhabitation effect of carburized layer. The inclusion induced fracture with fisheye occurs in the short life region below 5 × 10⁵ cycles, whereas the inclusion induced fracture with fine granular area (FGA) and fisheye occurs in the long life region beyond 10⁶ cycles. The stress intensity factor range at the front of FGA can be regarded as the threshold value controlling stable growth of interior long crack. The evaluated maximum inclusion size in the effective damage volume of specimen is about 27.29 μm. Considering the size relationships between fisheye and FGA, and inclusion, the developed life prediction method involving crack growth can be acceptable on the basis of the good agreement between the predicted and experimental results.
Pozzo, L; Cavallarin, L; Antoniazzi, S; Guerre, P; Biasibetti, E; Capucchio, M T; Schiavone, A
2013-05-01
The European Commission Recommendation 2006/576/EC indicates that the maximum tolerable level of ochratoxin A (OTA) in poultry feeds is 0.1 mg OTA/kg. Thirty-six 1-day-old male broiler chicks were divided into two groups, a control (basal diet) and an OTA (basal diet + 0.1 mg OTA/kg) group. The OTA concentration was quantified in serum, liver, kidney, breast and thigh samples. The thiobarbituric acid reactive substances (TBARS) content were evaluated in the liver, kidney, breast and thigh samples. The glutathione (GSH) content, and catalase (CAT) and superoxide dismutase (SOD) activity were measured in the liver and kidney samples. Histopathological traits were evaluated for the spleen, bursa of Fabricius and liver samples. Moreover, the chemical composition of the meat was analysed in breast and thigh samples. In the OTA diet-fed animals, a serum OTA concentration of 1.15 ± 0.35 ng/ml was found, and OTA was also detected in kidney and liver at 3.58 ± 0.85 ng OTA/g f.w. and 1.92 ± 0.21 ng OTA/g f.w., respectively. The TBARS content was higher in the kidney of the ochratoxin A group (1.53 ± 0.18 nmol/mg protein vs. 0.91 ± 0.25 nmol/mg protein). Feeding OTA at 0.1 mg OTA/kg also resulted in degenerative lesions in the spleen, bursa of Fabricius and liver. The maximum tolerable level of 0.1 mg OTA/kg, established for poultry feeds by the EU, represents a safe limit for the final consumer, because no OTA residues were found in breast and thigh meat. Even though no clinical signs were noticed in the birds fed the OTA-contaminated diet, moderate histological lesions were observed in the liver, spleen and bursa of Fabricius.
Reducing axial mixing in flotation columns
Al Taweel, A.M.; Ramadan, A.M. [Technical Univ. of Nova Scotia, Halifax (Canada). Chemical Engineering Dept.; Moharam, M.R.; Hassan, T.A. [Al Azhar Univ., Cairo (Egypt); El Mofty, S.M. [Cairo Univ., Giza (Egypt)
1995-10-01
The axial mixing characteristics of a pilot-scale flotation column were investigated with the objective of identifying means to mitigate the extent of axial mixing that adversely affects its grade/recovery performance. A wide range of design and operating conditions wa investigated and the experimental results, obtained using the dynamic response method, were analyzed using three axial mixing models. The dynamic response of the column can best be described using the axial dispersion model. The results obtained suggest that the value of the axial dispersion coefficient, E{sub L}, can be significantly reduced by judicial selection of hydrodynamic conditions and/or the use of column inserts that suppress the onset of hydrodynamic instabilities inherent to the operation of conventional flotation columns. Up to 40% reduction in the value of E{sub L} was thus obtained by using spargers that produce more uniform bubble sizes, while up to 30% reductions were obtained by controlling the residual frother concentration. 33 refs., 7 figs.
Axial super-resolution evanescent wave tomography.
Pendharker, Sarang; Shende, Swapnali; Newman, Ward; Ogg, Stephen; Nazemifard, Neda; Jacob, Zubin
2016-12-01
Optical tomographic reconstruction of a three-dimensional (3D) nanoscale specimen is hindered by the axial diffraction limit, which is 2-3 times worse than the focal plane resolution. We propose and experimentally demonstrate an axial super-resolution evanescent wave tomography method that enables the use of regular evanescent wave microscopes like the total internal reflection fluorescence microscope beyond surface imaging and achieve a tomographic reconstruction with axial super-resolution. Our proposed method based on Fourier reconstruction achieves axial super-resolution by extracting information from multiple sets of 3D fluorescence images when the sample is illuminated by an evanescent wave. We propose a procedure to extract super-resolution features from the incremental penetration of an evanescent wave and support our theory by one-dimensional (along the optical axis) and 3D simulations. We validate our claims by experimentally demonstrating tomographic reconstruction of microtubules in HeLa cells with an axial resolution of ∼130 nm. Our method does not require any additional optical components or sample preparation. The proposed method can be combined with focal plane super-resolution techniques like stochastic optical reconstruction microscopy and can also be adapted for THz and microwave near-field tomography.
Axial super-resolution evanescent wave tomography
Pendharker, Sarang; Shende, Swapnali; Newman, Ward; Ogg, Stephen; Nazemifard, Neda; Jacob, Zubin
2016-12-01
Optical tomographic reconstruction of a 3D nanoscale specimen is hindered by the axial diffraction limit, which is 2-3 times worse than the focal plane resolution. We propose and experimentally demonstrate an axial super-resolution evanescent wave tomography (AxSET) method that enables the use of regular evanescent wave microscopes like Total Internal Reflection Fluorescence Microscope (TIRF) beyond surface imaging, and achieve tomographic reconstruction with axial super-resolution. Our proposed method based on Fourier reconstruction achieves axial super-resolution by extracting information from multiple sets of three-dimensional fluorescence images when the sample is illuminated by an evanescent wave. We propose a procedure to extract super-resolution features from the incremental penetration of an evanescent wave and support our theory by 1D (along the optical axis) and 3D simulations. We validate our claims by experimentally demonstrating tomographic reconstruction of microtubules in HeLa cells with an axial resolution of $\\sim$130 nm. Our method does not require any additional optical components or sample preparation. The proposed method can be combined with focal plane super-resolution techniques like STORM and can also be adapted for THz and microwave near-field tomography.
Hongwei MA; Haokang JIANG
2005-01-01
This paper presents an experimental investigation of the characteristics of three-dimensional turbulent wakes of an isolated axial compressor rotor and a single-stage axial compressor rotor. The wakes were measured from hub to tip using a single-slant hot-wire and a four-hole conical high frequency pressure probe. The experiments were made at both design and near stall conditions. Variations of mean velocities, total pressure, static pressure and turbulence stresses in the wakes are shown and interpreted. The experimental data from the isolated compressor rotor wake are compared with that from the single-stage compressor rotor.
Borisevich, V. D.; Potanin, E. P.
2017-07-01
The possibility of using a rotating magnetic field (RMF) in a plasma centrifuge (PC), with axial circulation to multiply the radial separation effect in an axial direction, is considered. For the first time, a traveling magnetic field (TMF) is proposed to drive an axial circulation flow in a PC. The longitudinal separation effect is calculated for a notional model, using specified operational parameters and the properties of a plasma, comprising an isotopic mixture of 20Ne-22Ne and generated by a high frequency discharge. The optimal intensity of a circulation flow, in which the longitudinal separation effect reaches its maximum value, is studied. The optimal parameters of the RMF and TMF for effective separation, as well as the centrifuge performance, are calculated.
Prince, D. C., Jr.; Wisler, D. C.; Hilvers, D. E.
1975-01-01
The results of a program of experimental and analytical research in casing treatments over axial compressor rotor blade tips are presented. Circumferential groove, axial-skewed slot and blade angle slot treatments were tested at low speeds. With the circumferential groove treatment the stalling flow was reduced 5.8% at negligible efficiency sacrifice. The axial-skewed slot treatment improved the stalling flow by 15.3%; 1.8 points in peak efficiency were sacrificed. The blade angle slot treatment improved the stalling flow by 15.0%; 1.4 points in peak efficiency were sacrificed. The favorable stalling flow situations correlated well with observations of higher-than-normal surface pressures on the rotor blade pressure surfaces in the tip region, and with increased maximum diffusions on the suction surfaces. Annulus wall pressure gradients, especially in the 50 to 75% chord region, are also increased and blade surface pressure loadings are shifted toward the trailing edge for treated configurations.
Impact of Periodic Unsteadiness on Performance and Heat Load in Axial Flow Turbomachines
Sharma, Om P.; Stetson, Gary M.; Daniels, William A,; Greitzer, Edward M.; Blair, Michael F.; Dring, Robert P.
1997-01-01
Results of an analytical and experimental investigation, directed at the understanding of the impact of periodic unsteadiness on the time-averaged flows in axial flow turbomachines, are presented. Analysis of available experimental data, from a large-scale rotating rig (LSRR) (low speed rig), shows that in the time-averaged axisymmetric equations the magnitude of the terms representing the effect of periodic unsteadiness (deterministic stresses) are as large or larger than those due to random unsteadiness (turbulence). Numerical experiments, conducted to highlight physical mechanisms associated with the migration of combustor generated hot-streaks in turbine rotors, indicated that the effect can be simulated by accounting for deterministic stress like terms in the time-averaged mass and energy conservation equations. The experimental portion of this program shows that the aerodynamic loss for the second stator in a 1-1/2 stage turbine are influenced by the axial spacing between the second stator leading edge and the rotor trailing edge. However, the axial spacing has little impact on the heat transfer coefficient. These performance changes are believed to be associated with the change in deterministic stress at the inlet to the second stator. Data were also acquired to quantify the impact of indexing the first stator relative to the second stator. For the range of parameters examined, this effect was found to be of the same order as the effect of axial spacing.
Bearing Capacities of Different-Diameter Concrete-Filled Steel Tubes under Axial Compression
Wenjing Wang
2016-01-01
Full Text Available The bearing capacities of concrete-filled steel tubes are normally derived through experiments with small-scale specimens, but it is uncertain whether such derivations are appropriate for the much larger components used in practical engineering. This study therefore investigates the effect of different diameters (219, 426, 630, and 820 mm on the axial compression of short concrete columns in steel (Q235 tubes. It is found that the peak nominal stress decreases with increasing specimen size and that the axial bearing capacity is determined by three separate components: the cylinder compressive strength of the concrete, the improvement in strength due to the confining effect of the steel tube, and the longitudinal strength of the steel tube. At peak load, increases in the specimen diameter reduce the hoop stresses in the steel tube, thereby reducing the strengthening effect of confinement. Vertical stress in the steel tube is increased with diameter; therefore, the axial bearing capacity of the steel tube is directly related to the specimen size. Size effect coefficients for these three aspects of bearing capacity are defined and used to develop a size-dependent model for predicting the axial bearing capacity of large, concrete-filled steel tubes. The model is then validated against experimental data.
Atlanto-axial infection after acupuncture.
Robinson, A; Lind, C R P; Smith, R J; Kodali, V
2015-12-11
A 67-year-old man presented with neck cellulitis following acupuncture for cervical spondylosis. Blood cultures were positive for methicillin-sensitive Staphylococcus aureus. Increased neck pain and bacteraemia prompted MRI, which showed atlanto-axial septic arthritis without signs of infection of the tissues between the superficial cellulitic area and the atlanto-axial joint, thus making direct extension of infection unlikely. It is more likely that haematogenous spread of infection resulted in seeding in the atlanto-axial joint, with the proximity of the arthritis and acupuncture site being coincidental. Acupuncture is a treatment option for some indolent pain conditions. As such, acupuncture services are likely to be more frequently utilised. A history of acupuncture is rarely requested by the admitting doctor and seldom offered voluntarily by the patient, especially where the site of infection due to haematogenous spread is distant from the needling location. Awareness of infectious complications following acupuncture can reduce morbidity through early intervention.
Axial symmetry and conformal Killing vectors
Mars, M; Mars, Marc; Senovilla, Jose M.M.
1993-01-01
Axisymmetric spacetimes with a conformal symmetry are studied and it is shown that, if there is no further conformal symmetry, the axial Killing vector and the conformal Killing vector must commute. As a direct consequence, in conformally stationary and axisymmetric spacetimes, no restriction is made by assuming that the axial symmetry and the conformal timelike symmetry commute. Furthermore, we prove that in axisymmetric spacetimes with another symmetry (such as stationary and axisymmetric or cylindrically symmetric spacetimes) and a conformal symmetry, the commutator of the axial Killing vector with the two others mush vanish or else the symmetry is larger than that originally considered. The results are completely general and do not depend on Einstein's equations or any particular matter content.
Axial flow positive displacement worm gas generator
Murrow, Kurt David (Inventor); Giffin, Rollin George (Inventor); Fakunle, Oladapo (Inventor)
2010-01-01
An axial flow positive displacement engine has an inlet axially spaced apart and upstream from an outlet. Inner and outer bodies have offset inner and outer axes extend from the inlet to the outlet through first, second, and third sections of a core assembly in serial downstream flow relationship. At least one of the bodies is rotatable about its axis. The inner and outer bodies have intermeshed inner and outer helical blades wound about the inner and outer axes respectively. The inner and outer helical blades extend radially outwardly and inwardly respectively. The helical blades have first, second, and third twist slopes in the first, second, and third sections respectively. The first twist slopes are less than the second twist slopes and the third twist slopes are less than the second twist slopes. A combustor section extends axially downstream through at least a portion of the second section.
Improving the lattice axial vector current
Horsley, R. [Edinburgh Univ. (United Kingdom). School of Physics and Astronomy; Nakamura, Y. [RIKEN Advanced Institute for Computational Science, Kobe (Japan); Perlt, H.; Schiller, A. [Leipzig Univ. (Germany). Inst. fuer Theoretische Physik; Rakow, P.E.L. [Liverpool Univ. (United Kingdom). Theoretical Physics Div.; Schierholz, G. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Zanotti, J.M. [Adelaide Univ. (Australia). CSSM, Dept. of Physics
2015-11-15
For Wilson and clover fermions traditional formulations of the axial vector current do not respect the continuum Ward identity which relates the divergence of that current to the pseudoscalar density. Here we propose to use a point-split or one-link axial vector current whose divergence exactly satisfies a lattice Ward identity, involving the pseudoscalar density and a number of irrelevant operators. We check in one-loop lattice perturbation theory with SLiNC fermion and gauge plaquette action that this is indeed the case including order O(a) effects. Including these operators the axial Ward identity remains renormalisation invariant. First preliminary results of a nonperturbative check of the Ward identity are also presented.
Organocatalytic atroposelective synthesis of axially chiral styrenes
Zheng, Sheng-Cai; Wu, San; Zhou, Qinghai; Chung, Lung Wa; Ye, Liu; Tan, Bin
2017-05-01
Axially chiral compounds are widespread in biologically active compounds and are useful chiral ligands or organocatalysts in asymmetric catalysis. It is well-known that styrenes are one of the most abundant and principal feedstocks and thus represent excellent prospective building blocks for chemical synthesis. Driven by the development of atroposelective synthesis of axially chiral styrene derivatives, we discovered herein the asymmetric organocatalytic approach via direct Michael addition reaction of substituted diones/ketone esters/malononitrile to alkynals. The axially chiral styrene compounds were produced with good chemical yields, enantioselectivities and almost complete E/Z-selectivities through a secondary amine-catalysed iminium activation strategy under mild conditions. Such structural motifs are important precursors for further transformations into biologically active compounds and synthetic useful intermediates and may have potential applications in asymmetric synthesis as olefin ligands or organocatalysts.
Improving the lattice axial vector current
Horsley, R; Perlt, H; Rakow, P E L; Schierholz, G; Schiller, A; Zanotti, J M
2015-01-01
For Wilson and clover fermions traditional formulations of the axial vector current do not respect the continuum Ward identity which relates the divergence of that current to the pseudoscalar density. Here we propose to use a point-split or one-link axial vector current whose divergence exactly satisfies a lattice Ward identity, involving the pseudoscalar density and a number of irrelevant operators. We check in one-loop lattice perturbation theory with SLiNC fermion and gauge plaquette action that this is indeed the case including order $O(a)$ effects. Including these operators the axial Ward identity remains renormalisation invariant. First preliminary results of a nonperturbative check of the Ward identity are also presented.
Tripathi, Siddhi; Amarnath, Gowdagere Shamanna; Muddugangadhar, Byrasandra Channapa; Sharma, Ashish; Choudhary, Suchismita
2014-12-01
To assess the effect of preparation taper, height and margin design under different loading conditions on cement lute stress. A 3-D FE model of an upper second premolar and molar was developed from CT scan of human skull using software programmes (MIMICS, Hypermesh and ANSYS). 10° and 30° taper, 3 and 5 mm preparation height and shoulder and chamfer finish lines were used. Type 1 Glass ionomer cement with 24 μm lute width was taken and the model was loaded under 100 N horizontal point load, vertical point load distributed axial load. The maximum shear stress and Von Mises stress within the cement lute were recorded. The maximum shear stresses ranged from 1.70 to 3.93 MPa (horizontal point loading), 0.66 to 3.04 MPa (vertical point loading), 0.38 to 0.87 MPa (distributed loading). The maximum Von Mises stresses ranged from 3.39 to 10.62 MPa (horizontal point loading), 1.93 to 8.58 MPa (vertical point loading) and 1.49 to 3.57 MPa (distributed loading). The combination of 10° taper and 5 mm height had the lowest stress field while the combination of 30° taper and 5 mm height had the highest stress field. Distributed axial loading shows least stress, better stress homogenization and gives a favorable prognosis for the fixed prostheses. Smaller preparation taper of 10° is biomechanically more acceptable than a 30° taper. It is desirable to decrease taper as height increases. The chamfer margin design is associated with greater local cement stresses toward the margins that could place the cement at greater risk for microfracture and failure.
Behaviour of M30 Grade concrete with confinement under axial compression
C.Vinil Babu
2014-09-01
Full Text Available The strength and durability of concrete have undergone continuous improvement. Over the years and these improved materials are now commonly used. In the present experimental investigation the behaviour of M30 grade concrete with and without confinement for different percentages of replacement of silica fume is studied under axial compression as per IS mix design. The 150mm x 300mm cylindrical specimens were cast with and without confinement and investigating the mechanical properties like axial compressive strength and stress – strain behaviour. It was observed that the confinement of concrete has increased the 28days strength for different percentages of confinement and that the peak stress and corresponding strain at peak stress increased with increase in percentages of confinement
郑文杰; 贺鸿志; 黄峙; 杨芳; 郭宝江
2003-01-01
研究了硒(Na 2SeO3)和碲(Na 2TeO 3)胁迫对钝顶螺旋藻(Spirulina platensis)和极大螺旋藻(Spirulina maximum)生长的影响.结果表明,两种藻对硒、碲表现出不同的耐性.对于S.platenis,CSe≤200mg/L促进生长,CTe＜100mg/L影响不大,CTe≥100mg/L抑制生长,CSa≥800mg/L或CTe=400mg/L藻死亡;而对于S.maiximum,CSe=25 mg/L时促进生长,CTe≤25mg/L无影响,CTe≥50 mg/L明显抑制生长,Cse≥800mg/L或CTe≥600 mg/L则死亡.而在培养周期内分次添加硒、碲,当累计达到CSe(CTe)=800mg/L,两种藻仍能正常生长.表明硒、碲添加方式不同,产生明显不同的效应.
Axial loaded MRI of the lumbar spine
Saifuddin, A. E-mail: asaifuddin@aol.com; Blease, S.; MacSweeney, E
2003-09-01
Magnetic resonance imaging is established as the technique of choice for assessment of degenerative disorders of the lumbar spine. However, it is routinely performed with the patient supine and the hips and knees flexed. The absence of axial loading and lumbar extension results in a maximization of spinal canal dimensions, which may in some cases, result in failure to demonstrate nerve root compression. Attempts have been made to image the lumbar spine in a more physiological state, either by imaging with flexion-extension, in the erect position or by using axial loading. This article reviews the literature relating to the above techniques.
Water Ingestion Into Axial Flow Compressors
1976-08-01
AFAPL-TR-76-77 WATER INGESTION INTO AXIAL FLOW COMPRESSORS PURDUE UNIVERSITY SCHOOL OF AERONAUTICS AND ASTRONA UTICS S WEST LAFAYETTE, INDIANA 47907...CIPIENT’S CATALOG NUMBER TITL _07" 0 EREO Final i-7 0 Water Ingestion Into Axial Flow Compressorse 1 Auq 75 -: 31 Au0 a6 114o’ H-WPAFB-T-76-l:P ."CO TACT...necessary and Idenify by block number) Water ingestion , turbomachinery, and jet engines. 20 ABSTRACT (Contlinue on tov.ras side Hi necessary and Identify
«FLARES» IN AXIAL SPONDYLOARTHRITIS
Sh. F. Erdes
2016-01-01
Full Text Available The clear definition of the concept of «flare in axial spondyloarthritis» is of paramount importance for clinical trials and routine practice in particular. It will be able to unify the characteristics of outcomes over a particular period of time on the one hand and to standardize therapeutic approaches on the other. On 4 February 2016, the journal Annals of Rheumatic Diseases published the on-line paper «Preliminary definitions of 'flare' in axial spondyloarthritis, based on pain, BASDAI and ASDAS-CRP: an ASAS initiative» by L. Gossec et al., which was devoted to this topic.
Optimization of Axial Intensity Point Spread Function
WANG Haifeng; GAN Fuxi; CHEN Zhongyu
2001-01-01
It is known that for the converged laser beam, the axial intensity distribution corresponds to a Gaussian curve, that is, the intensity on the focal plane is the peak intensity. When it defocuses, the intensity would decrease rapidly. In optical data storage, for instance, we expect the intensity within a certain distance to be almost equal. In this paper, we propose to use a pure phase superresolution apodizer to optimize the axial intensity distribution of the converged laser beam and at the same time improve the resolution. The intensity point spread function remains almost identical in a wide range within the focal depth.
Axial Nucleon form factors from lattice QCD
Alexandrou, C; Carbonell, J; Constantinou, M; Harraud, P A; Guichon, P; Jansen, K; Korzec, T; Papinutto, M
2010-01-01
We present results on the nucleon axial form factors within lattice QCD using two flavors of degenerate twisted mass fermions. Volume effects are examined using simulations at two volumes of spatial length $L=2.1$ fm and $L=2.8$ fm. Cut-off effects are investigated using three different values of the lattice spacings, namely $a=0.089$ fm, $a=0.070$ fm and $a=0.056$ fm. The nucleon axial charge is obtained in the continuum limit and chirally extrapolated to the physical pion mass enabling comparison with experiment.
Axial Vircator for Electronic Warfare Applications
L. Drazan
2009-12-01
Full Text Available This paper deals with a high power microwave generator with virtual cathode – vircator in axial release for electronic warfare applications. The classification of directed energy weapons microwave (DEWM is introduced together with basic block diagrams of a particular class of DEWM. In the paper, methods for designing vircator pulsed power supply, axial vircator structure, measurement methods and experimental results are presented. The vircator in electromagnetic ammunition is powered by magneto-cumulative generator and in weapons for defense of objects (WDO, it is powered by Marx generator. The possible applications of a vircator in the DEWM area are discussed.
Scalar Resonances in Axially Symmetric Spacetimes
Ranea-Sandoval, Ignacio F
2015-01-01
We study properties of resonant solutions to the scalar wave equation in several axially symmetric spacetimes. We prove that non-axial resonant modes do not exist neither in the Lanczos dust cylinder, the $(2+1)$ extreme BTZ spacetime nor in a class of simple rotating wormhole solutions. Moreover, we find unstable solutions to the wave equation in the Lanczos dust cylinder and in the $r^2 <0$ region of the extreme $(2+1)$ BTZ spacetime, two solutions that possess closed timelike curves. Similarities with previous results obtained for the Kerr spacetime are explored.
ANALYSIS OF THE AXIAL GAP VS FIBERBOARD MOISTURE CONTENT IN A 9975 SHIPPING PACKAGE
Daugherty, W.
2013-09-30
The fiberboard assembly within a 9975 shipping package contains a modest amount of moisture, which can migrate to the cooler regions of the package when an internal heat load is present. Typically, this leads to increased moisture levels in the bottom fiberboard layers, along with elevated chloride levels which can leach from the fiberboard. Concerns have been raised that this condition could lead to corrosion of the stainless steel drum. It has been postulated that checking the axial gap at the top of the package against the current 1 inch maximum criterion provides a sufficient indication regarding the integrity of the fiberboard and drum. This report estimates the increase in axial gap that might be expected for a given moisture increase in the bottom fiberboard layers, and the likelihood that the increase will create a nonconforming condition that will lead to identification of the moisture increase. Using data relating the fiberboard moisture content with the degree of compaction under load, the present analysis indicates that the axial gap will increase by 0.282 inch as the bottom fiberboard layers approach the saturation point. This increase will cause approximately 58% of packages with otherwise nominal package component dimensions to fail the axial gap criterion, based on a survey of axial gap values recorded in K-Area surveillance activities. As the moisture content increases above saturation, the predicted increase in axial gap jumps to 0.405 inch, which would result in 92% or more of all packages failing the axial gap criterion. The data and analysis described in this report are specific to cane fiberboard. While it is expected that softwood fiberboard will behave similarly, such behavior has not yet been demonstrated.
韩铁林; 师俊平; 陈蕴生; 李伟红
2016-01-01
This article take the actual rock mass project as a background, triaxial compression for sandstone specimen under axial unloading and radial unloading—this path is realized on WDT-1500 reactive material testing machine. The test results show that the failure of sandstone specimen don’t appear peak stress under axial unloading and radial unloading—this path, to define the inflection point of stress drop of (The maximum principal stress-minimum principal stress)∼the minimum principal stress curves of sandstone for failure strength. The stress drop and the axial strain of resilience of sandstone specimens were happened under axial unloading and radial unloading, which had no obvious elasticity and yield step before rock specimens’ failure. The lateral deformation is larger than the axial deformation in the process of test,and volumetric strain of the sandstone specimen is always in a state of expansion. The strength of sandstone is reduced relative to triaxial compression. the deformation property and strength property of sandstone under this path are mainly influenced by initial axial pressure and initial radial pressure,but the influence of the unloading speed of radial pressure is not clear. The failure characteristics of samples often present mixed zhang-shear failure under axial unloading and radial unloading.%本文以实际岩体工程为背景，利用WDT-1500仪器开展了轴向、侧向同时卸荷条件下砂岩的三轴试验。结果表明：轴、侧向同卸荷这种卸荷路径下，砂岩试样破坏时并没有出现应力峰值，为了定义试样的破坏强度，将最大与最小主应力差随最小主应力的变化关系曲线上应力跌落的拐点处的应力值定义为破坏强度。砂岩变形初始段发生应力跌落和轴向应变回弹，破坏前无明显的弹性和屈服阶段；试验的过程中，砂岩的侧向变形明显大于轴向变形，其体积应变一直处于膨胀状态；相对于砂岩的常规三
The Effect of Ultrapolish on a Transonic Axial Rotor
Roberts, William B.; Thorp, Scott; Prahst, Patricia S.; Strazisar, Anthony
2005-01-01
Back-to-back testing has been done using NASA fan rotor 67 in the Glenn Research Center W8 Axial Compressor Test Facility. The rotor was baseline tested with a normal industrial RMS surface finish of 0.5-0.6 m (20-24 microinches) at 60, 80 and 100% of design speed. At design speed the tip relative Mach number was 1.38. The blades were then removed from the facility and ultrapolished to a surface finish of 0.125 m (5 microinch) or less and retested. At 100% speed near the design point, the ultrapolished blades showed approximately 0.3 - 0.5% increase in adiabatic efficiency. The difference was greater near maximum flow. Due to increased relative measurement error at 60 and 80% speed, the performance difference between the normal and ultrapolished blades was indeterminate at these speeds.
Non-destructive testing of biaxial stress state in ferromagnetic materials
Vengrinovich, V. L.; Vintov, D. A.; Dmitrovich, D. V.
2014-02-01
The technique for biaxial stress state quantitative non destructive testing using magnetic, namely Barkhausen Noise, measurements is developed and checked experimentally. The main elaboration concerns the application of uni-axial calibration data for bi-axial stress measurement in the material which treatment pre-history is not definitely known. The article is aimed to get over difficulties, accompanying factual nondestructive stress evaluation, implied from its tensor nature. The developed technique of stress calibration and measurement assumes the bi-axial stress components recovery from uni-axial magnetic and Barkhausen noise measurement results. The complete technology, based on new calibration procedure with grid diagrams is considered in the article.
Hathaway, Michael D.
1986-01-01
Measurements of the unsteady velocity field within the stator row of a transonic axial-flow fan were acquired using a laser anemometer. Measurements were obtained on axisymmetric surfaces located at 10 and 50 percent span from the shroud, with the fan operating at maximum efficiency at design speed. The ensemble-average and variance of the measured velocities are used to identify rotor-wake-generated (deterministic) unsteadiness and turbulence, respectively. Correlations of both deterministic and turbulent velocity fluctuations provide information on the characteristics of unsteady interactions within the stator row. These correlations are derived from the Navier-Stokes equation in a manner similar to deriving the Reynolds stress terms, whereby various averaging operators are used to average the aperiodic, deterministic, and turbulent velocity fluctuations which are known to be present in multistage turbomachines. The correlations of deterministic and turbulent velocity fluctuations throughout the axial fan stator row are presented. In particular, amplification and attenuation of both types of unsteadiness are shown to occur within the stator blade passage.
LDA measurements on the turbulent flow characteristics of a small-sized axial fan
Kim, Jang Kweon [Kunsan National Univ., Kunsan (Korea, Republic of)
2001-07-01
The operating point of a small-sized axial fan for refrigerator is strongly dependent upon the system resistance. Therefore, the turbulent flow characteristics around a small-sized axial fan may change significantly according to the operating point. This study represents three-dimensional turbulent flow characteristics around a small-sized axial fan measured at the four operating points such as {phi}=0.1, 0.18, 0.25 and 0.32 by using fiber-optic type LDA system. This LDA system is composed of a 5 W Argon-ion laser, two optics in back-scatter mode, three BSA's, a PC, and a three-dimensional automatic traversing system. A kind of paraffin fluid is utilized for supplying particles by means of fog generator. Mean velocity profiles downstream of a small--sized axial fan along the radial distance show that both the streamwise and the tangential components exist predominantly in downstream except {phi}=0.1 and have a maximum value at the radial distance ratio of about 0.8, but the radial component, which its velocity is relatively small, is acting role that only turns flow direction to the outside or the central part of axial fan. Moreover, all of the velocity components downstream at {phi}=0.1 show much smaller than those upstream due to the static pressure rise at the low-flowrate region.
HUANG Lin; JIAN Guang-de; QIU Xiao-ming
2007-01-01
The synergistic stabilizing effect of gyroviscosity and sheared axial flow on the Rayleigh-Taylor instability in Z-pinch implosions is studied by means of the incompressible viscid magneto-hydrodynamic equations. The gyroviscosity (or finite Larmor radius) effects are introduced in the momentum equation through an anisotropic ion stress tensor. Dispersion relation with the effect of a density discontinuity is derived. The results indicate that the short-wavelength modes of the Rayleigh-Taylor instability are easily stabilized by the gyroviscosity effects. The long wavelength modes are stabilized by the sufficient sheared axial flow. However, the synergistic effects of the finite Larmor radius and sheared axial flow can heavily mitigate the Rayleigh-Taylor instability. This synergistic effect can compress the Rayleigh-Taylor instability to a narrow wave number region. Even with a sufficient gyroviscosity and large enough flow velocity, the synergistic effect can completely suppressed the Rayleigh-Taylor instability in whole wave number region.
OECD Maximum Residue Limit Calculator
With the goal of harmonizing the calculation of maximum residue limits (MRLs) across the Organisation for Economic Cooperation and Development, the OECD has developed an MRL Calculator. View the calculator.
Excitation modes in non-axial nuclei
Leviatan, A.; Ginnochio, J.N.
1990-01-01
Excitation modes of non-axial quadrupole shapes are investigated in the framework of interacting boson models. Both {gamma}-unstable and {gamma}-rigid nuclear shapes are considered for systems with one type of boson as well as with proton-neutron bosons. 6 refs.
Cystic lesions accompanying extra-axial tumours
Lohle, PNM; Wurzer, HAL; Seelen, PJ; Kingma, LM; Go, KG
1999-01-01
We examined the mechanism of cyst formation in extra-axial tumours in the central nervous system (CNS). Cyst fluid, cerebrospinal fluid (CSF) and blood plasma were analysed in eight patients with nine peritumoral cysts: four with meningiomas, two with intracranial and two spinal intradural schwannom
Knowledge Based Design of Axial Flow Compressor
Dinesh kumar.R
2015-05-01
Full Text Available In the aerospace industry with highly competitive market the time to design and delivery is shortening every day. Pressure on delivering robust product with cost economy is in demand in each development. Even though technology is older, it is new for each customer requirement and highly non-liner to fit one in another place. Gas turbine is considered one of a complex design in the aircraft system. It involves experts to be grouped with designers of various segments to arrive the best output. The time is crucial to achieve a best design and it needs knowledge automation incorporated with CAD/CAE tools. In the present work an innovative idea in the form of Knowledge Based Engineering for axial compressor is proposed, this includes the fundamental design of axial compressor integrated with artificial intelligence in the form of knowledge capturing and programmed with high level language (Visual Basis.Net and embedded into CATIA v5. This KBE frame work eases out the design and modeling of axial compressor design and produces 3D modeling for further flow simulation with fluid dynamic in Ansys-Fluent. Most of the aerospace components are developed through simulation driven product development and in this case it is established for axial compressor.
Investigations on Experimental Impellers for Axial Blowers
Encke, W.
1947-01-01
A selection of measurements obtained on experimental impellers for axial blowers will be reported. In addition to characteristic curves plotted for low and for high peripheral velocities, proportions and blade sections for six different blower models and remarks on the design of blowers will be presented.
Wave propagation in axially moving periodic strings
Sorokin, Vladislav S.; Thomsen, Jon Juel
2017-01-01
The paper deals with analytically studying transverse waves propagation in an axially moving string with periodically modulated cross section. The structure effectively models various relevant technological systems, e.g. belts, thread lines, band saws, etc., and, in particular, roller chain drive...
Research on Flow Characteristics of Supercritical CO2 Axial Compressor Blades by CFD Analysis
Takagi, Kazuhisa; Muto, Yasushi; Ishizuka, Takao; Kikura, Hiroshige; Aritomi, Masanori
A supercritical CO2 gas turbine of 20MPa is suitable to couple with the Na-cooled fast reactor since Na - CO2 reaction is mild at the outlet temperature of 800K, the cycle thermal efficiency is relatively high and the size of CO2 gas turbine is very compact. In this gas turbine cycle, a compressor operates near the critical point. The property of CO2 and then the behavior of compressible flow near the critical point changes very sharply. So far, such a behavior is not examined sufficiently. Then, it is important to clarify compressible flow near the critical point. In this paper, an aerodynamic design of the axial supercritical CO2 compressor for this system has been carried out based on the existing aerodynamic design method of Cohen1). The cycle design point was selected to achieve the maximum cycle thermal efficiency of 43.8%. For this point, the compressor design conditions were determined. They are a mass flow rate of 2035kg/s, an inlet temperature of 308K, an inlet static pressure of 8.26MPa, an outlet static pressure of 20.6MPa and a rotational speed of 3600rpm. The mean radius was constant through axial direction. The design point was determined so as to keep the diffusion factor and blade stress within the allowable limits. Number of stages and an expected adiabatic efficiency was 14 and 87%, respectively. CFD analyses by FLUENT have been done for this compressor blade. The blade model consists of one set of a guide vane, a rotor blade and a stator blade. The analyses were conducted under the assumption both of the real gas properties and also of the modified ideal gas properties. Using the real gas properties, analysis was conducted for the 14th blade, whose condition is remote from the critical point and the possibility of divergence is very small. Then, the analyses were conducted for the blade whose conditions are nearer to the critical point. Gradually, divergence of calculation was encountered. Convergence was relatively easy for the modified ideal
Effects of the three-dimensional residual stresses on the mechanical properties of arterial walls.
Zheng, Xianbing; Ren, Jiusheng
2016-03-21
Effects of the three-dimensional residual stresses on the mechanical properties of arterial walls are analyzed in this paper, based on the model which considered the bending and stretching both in the circumferential and axial directions of the three distinct arterial layers. Moreover, different constitutive models are proposed to quantify the nonlinear mechanics of the three distinct layers and the important constituents, i.e. elastin, collagen fibers and smooth muscle cells (SMCs), are all taken into account. The stress distributions and pressure-radius curves of the arterial wall are given in details. Results demonstrate that the maximum values of the circumferential stress and the corresponding stress gradient in the media under the mean arterial pressure are reduced significantly as a consequence of the SMCs. The bending in the axial direction of the media and the opening angle of the intima have an obvious impact on the mechanical behaviors of arterial walls. This study may not only develop the understanding of effects of the three-dimensional residual stresses on the arterial wall response, but also can increase the accuracy of the analyses for patient-specific studies used for the treatments of arterial diseases. Copyright © 2016 Elsevier Ltd. All rights reserved.
Estimation of the shear stress on the surface of an aortic valve leaflet.
Weston, M W; LaBorde, D V; Yoganathan, A P
1999-01-01
The limited durability of xenograft heart valves and the limited supply of allografts have sparked interest in tissue engineered replacement valves. A bioreactor for tissue engineered valves must operate at conditions that optimize the biosynthetic abilities of seeded cells while promoting their adherence to the leaflet matrix. An important parameter is shear stress, which is known to influence cellular behavior and may thus be crucial in bioreactor optimization. Therefore, an accurate estimate of the shear stress on the leaflet surface would not only improve our understanding of the mechanical environment of aortic valve leaflets, but it would also aid in bioreactor design. To estimate the shear stress on the leaflet surface, two-component laser-Doppler velocimetry measurements have been conducted inside a transparent polyurethane valve with a trileaflet structure similar to the native aortic valve. Steady flow rates of 7.5, 15.0, and 22.5 L/min were examined to cover the complete range possible during the cardiac cycle. The laminar shear stresses were calculated by linear regression of four axial velocity measurements near the surface of the leaflet. The maximum shear stress recorded was 79 dyne/cm2, in agreement with boundary layer theory and previous experimental and computational studies. This study has provided a range of shear stresses to be explored in bioreactor design and has defined a maximum shear stress at which cells must remain adherent upon a tissue engineered construct.
Advanced AC permanent magnet axial flux disc motor for electric passenger vehicle
Kliman, G. B.
1982-01-01
An ac permanent magnet axial flux disc motor was developed to operate with a thyristor load commutated inverter as part of an electric vehicle drive system. The motor was required to deliver 29.8 kW (40 hp) peak and 10.4 kW (14 hp) average with a maximum speed of 11,000 rpm. It was also required to run at leading power factor to commutate the inverter. Three motors were built.
Maximum margin Bayesian network classifiers.
Pernkopf, Franz; Wohlmayr, Michael; Tschiatschek, Sebastian
2012-03-01
We present a maximum margin parameter learning algorithm for Bayesian network classifiers using a conjugate gradient (CG) method for optimization. In contrast to previous approaches, we maintain the normalization constraints on the parameters of the Bayesian network during optimization, i.e., the probabilistic interpretation of the model is not lost. This enables us to handle missing features in discriminatively optimized Bayesian networks. In experiments, we compare the classification performance of maximum margin parameter learning to conditional likelihood and maximum likelihood learning approaches. Discriminative parameter learning significantly outperforms generative maximum likelihood estimation for naive Bayes and tree augmented naive Bayes structures on all considered data sets. Furthermore, maximizing the margin dominates the conditional likelihood approach in terms of classification performance in most cases. We provide results for a recently proposed maximum margin optimization approach based on convex relaxation. While the classification results are highly similar, our CG-based optimization is computationally up to orders of magnitude faster. Margin-optimized Bayesian network classifiers achieve classification performance comparable to support vector machines (SVMs) using fewer parameters. Moreover, we show that unanticipated missing feature values during classification can be easily processed by discriminatively optimized Bayesian network classifiers, a case where discriminative classifiers usually require mechanisms to complete unknown feature values in the data first.
Maximum Entropy in Drug Discovery
Chih-Yuan Tseng
2014-07-01
Full Text Available Drug discovery applies multidisciplinary approaches either experimentally, computationally or both ways to identify lead compounds to treat various diseases. While conventional approaches have yielded many US Food and Drug Administration (FDA-approved drugs, researchers continue investigating and designing better approaches to increase the success rate in the discovery process. In this article, we provide an overview of the current strategies and point out where and how the method of maximum entropy has been introduced in this area. The maximum entropy principle has its root in thermodynamics, yet since Jaynes’ pioneering work in the 1950s, the maximum entropy principle has not only been used as a physics law, but also as a reasoning tool that allows us to process information in hand with the least bias. Its applicability in various disciplines has been abundantly demonstrated. We give several examples of applications of maximum entropy in different stages of drug discovery. Finally, we discuss a promising new direction in drug discovery that is likely to hinge on the ways of utilizing maximum entropy.
Lei, Xiao; Narsu, B.; Yun, Guohong; Li, Jiangang; Yao, Haiyan
2016-05-01
Surface effects play a deterministic role in the physical and mechanical properties of nanosized materials and structures. In this paper, we present a self-consistent theoretical scheme for describing the elasticity of nanowires. The natural frequency and the critical compression force of axial buckling are obtained analytically, taking into consideration the influences of lower symmetry, additional elastic parameters, surface reconstruction, surface elasticity, and residual surface stress. Applications of the present theory to elastic systems for the axially oriented Si and Cu nanowires and Ag axially oriented nanowires yield good agreement with experimental data and calculated results. The larger positive value of the new elastic parameter c12α taken into account for Si oriented nanowires drives the curves of natural frequency and critical compression force versus thickness towards the results obtained from density functional theory simulation. Negative surface stress decreases the critical load for axial buckling, thus making the nanowires very easy to bend into various structures. The present study is envisaged to provide useful insights for the design and application of nanowire-based devices.
Jian Guangde; Huang Lin; Qiu Xiaoming
2005-01-01
The assembling stabilizing effect of the finite Larmor radius (FLR) and the sheared axial flow (SAF) on the Rayleigh-Taylor instability in Z-pinch implosions is studied by means of the incompressible finite Larmor radius magnetohydrodynamic (MHD) equations. The finite Larmor radius effects are introduced in the momentum equation with the sheared axial flow through an anisotropic ion stress tensor. In this paper a linear mode equation is derived that is valid for arbitrary kL, where k is the wave number and L is the plasma shell thickness. Numerical solutions are presented. The results indicate that the short-wavelength modes of the RayleighTaylor instability are easily stabilized by the individual effect of the finite Larmor radius or the sheared axial flow. The assembling effects of the finite Larmor radius and sheared axial flow can heavily mitigate the Rayleigh-Taylor instability, and the unstable region can be compressed considerably.
Masi, Alfonse T.
2014-01-01
Ankylosing spondylitis and axial spondyloarthropathy have characteristic age- and sex-specific onset patterns, typical entheseal lesions, and marked heritability, but the integrative mechanisms causing the pathophysiological and structural alterations remain largely undefined. Myofascial tissues are integrated in the body into webs and networks which permit transmission of passive and active tensional forces that provide stabilizing support and help to control movements. Axial myofascial hype...
Masi, Alfonse T.
2014-01-01
Ankylosing spondylitis and axial spondyloarthropathy have characteristic age- and sex-specific onset patterns, typical entheseal lesions, and marked heritability, but the integrative mechanisms causing the pathophysiological and structural alterations remain largely undefined. Myofascial tissues are integrated in the body into webs and networks which permit transmission of passive and active tensional forces that provide stabilizing support and help to control movements. Axial myofascial hype...
Greenslade, Thomas B., Jr.
1985-01-01
Discusses a series of experiments performed by Thomas Hope in 1805 which show the temperature at which water has its maximum density. Early data cast into a modern form as well as guidelines and recent data collected from the author provide background for duplicating Hope's experiments in the classroom. (JN)
Abolishing the maximum tension principle
Dabrowski, Mariusz P
2015-01-01
We find the series of example theories for which the relativistic limit of maximum tension $F_{max} = c^2/4G$ represented by the entropic force can be abolished. Among them the varying constants theories, some generalized entropy models applied both for cosmological and black hole horizons as well as some generalized uncertainty principle models.
Abolishing the maximum tension principle
Mariusz P. Da̧browski
2015-09-01
Full Text Available We find the series of example theories for which the relativistic limit of maximum tension Fmax=c4/4G represented by the entropic force can be abolished. Among them the varying constants theories, some generalized entropy models applied both for cosmological and black hole horizons as well as some generalized uncertainty principle models.
K Athiannan; R Palaninathan
2004-02-01
This paper presents experimental studies on buckling of cylindrical shell models under axial and transverse shear loads. Tests are carried out using an experimental facility specially designed, fabricated and installed, with provision for in-situ measurement of the initial geometric imperfections. The shell models are made by rolling and seam welding process and hence are expected to have imperfections more or less of a kind similar to that of real shell structures. The present work thus differs from most of the earlier investigations. The measured maximum imperfections $\\delta_{\\text{max}}$ are of the order of $\\pm 3t$ (t = thickness). The buckling loads obtained experimentally are compared with the numerical buckling values obtained through ﬁnite element method (FEM). In the case of axial buckling, the imperfect geometry is obtained in four ways and in the case of transverse shear buckling, the FE modelling of imperfect geometry is done in two ways. The initial geometric imperfections affect the load carrying capacity. The load reduction is considerable in the case of axial compression and is marginal in the case of transverse shear buckling. Comparisons between experimental buckling loads under axial compression, reveal that the extent of imperfection, rather than its maximum value, in a specimen inﬂuences the failure load. Buckling tests under transverse shear are conducted with and without axial constraints. While differences in experimental loads are seen to exist between the two conditions, the numerical values are almost equal. The buckling modes are different, and the experimentally observed and numerically predicted values are in complete disagreement.
A cylindrical shell with an axial crack under skew-symmetric loading.
Yuceoglu, U.; Erdogan, F.
1973-01-01
The skew-symmetric problem for a cylindrical shell containing an axial crack is considered. It is assumed that the material has a special orthotropy - namely, that the shear modulus may be evaluated from the measured Young's moduli and Poisson ratios and is not an independent material constant. The problem is solved within the confines of an eighth-order linearized shallow shell theory. As numerical examples, the torsion of an isotropic cylinder and that of a specially orthotropic cylinder (titanium) are considered. The membrane and bending components of the stress intensity factor are calculated and are given as functions of a dimensionless shell parameter. In the torsion problem for the axially cracked cylinder the bending effects appear to be much more significant than that found for the circumferentially cracked cylindrical shell. Also, as the shell parameter increases, unlike the results found in the pressurized shell, the bending stresses around crack ends do not change sign.
Ross, Mark Hamilton
Experimental and computational studies were conducted to study the role of the tip leakage flow in axial compressor stall and the relationship between the tip clearance flow flow field and surge margin extension from circumferential groove casing treatment. The CFD results were used to identify the existence of an interface between the approach ow and the tip-leakage flow. The experiments used a surface streaking visualization method to identify the time-averaged location of this interface as a line of zero axial shear stress at the casing. The axial position of this line, denoted xzs, moved upstream with decreasing ow coefficient in both the experiments and computations. The line was consistently located at the rotor leading edge plane at the stalling flow coefficient, regardless of in flow boundary condition. These results were successfully modeled using a control volume approach that balanced the reverse axial momentum ux of the tip-leakage flow with the momentum flux of the approach fluid. Non-uniform tip clearance measurements demonstrated that movement of the interface upstream of the rotor leading edge plane leads to the generation of short length scale rotating disturbances. Therefore, stall was interpreted as a critical point in the momentum flux balance of the approach ow and the reverse axial momentum flux of the tip-leakage flow. Experimental measurements of surge margin extension from seven CGCT configurations with a fixed groove geometry demonstrated that the contribution of individual grooves in a multi-groove casing to surge margin extension is an (a) additive and (b) linear function of the smooth wall tip clearance axial momentum ux at the location of a each groove. Extending the axial momentum model to include the in uence of a CGCT showed that circumferential grooves reduce the tip leakage flow axial momentum through radial transport. The equivalent force due to a circumferential groove was demonstrated to be related to the smooth wall tip
Piping inspection carriage having axially displaceable sensor
Zollinger, William T.; Treanor, Richard C.
1994-01-01
A pipe inspection instrument carriage for use with a pipe crawler for performing internal inspections of piping surfaces. The carriage has a front leg assembly, a rear leg assembly and a central support connecting the two assemblies and for mounting an instrument arm having inspection instruments. The instrument arm has a y-arm mounted distally thereon for axially aligning the inspection instrumentation and a mounting block, a linear actuator and axial movement arm for extending the inspection instruments radially outward to operably position the inspection instruments on the piping interior. Also, the carriage has a rotation motor and gear assembly for rotating the central support and the front leg assembly with respect to the rear leg assembly so that the inspection instruments azimuthally scan the piping interior. The instrument carriage allows performance of all piping inspection operations with a minimum of moving parts, thus decreasing the likelihood of performance failure.
Direct optical nanoscopy with axially localized detection
Bourg, N; Dupuis, G; Barroca, T; Bon, P; Lécart, S; Fort, E; Lévêque-Fort, S
2014-01-01
Evanescent light excitation is widely used in super-resolution fluorescence microscopy to confine light and reduce background noise. Herein we propose a method of exploiting evanescent light in the context of emission. When a fluorophore is located in close proximity to a medium with a higher refractive index, its near-field component is converted into light that propagates beyond the critical angle. This so-called Supercritical Angle Fluorescence (SAF) can be captured using a hig-NA objective and used to determine the axial position of the fluorophore with nanometer precision. We introduce a new technique for 3D nanoscopy that combines direct STochastic Optical Reconstruction Microscopy (dSTORM) imaging with dedicated detection of SAF emission. We demonstrate that our approach of a Direct Optical Nanoscopy with Axially Localized Detection (DONALD) yields a typical isotropic 3D localization precision of 20 nm.
Axial flow positive displacement worm compressor
Murrow, Kurt David (Inventor); Giffin, Rollin George (Inventor); Fakunle, Oladapo (Inventor)
2010-01-01
An axial flow positive displacement compressor has an inlet axially spaced apart and upstream from an outlet. Inner and outer bodies have offset inner and outer axes extend from the inlet to the outlet through first and second sections of a compressor assembly in serial downstream flow relationship. At least one of the bodies is rotatable about its axis. The inner and outer bodies have intermeshed inner and outer helical blades wound about the inner and outer axes respectively. The inner and outer helical blades extend radially outwardly and inwardly respectively. The helical blades have first and second twist slopes in the first and second sections respectively. The first twist slopes are less than the second twist slopes. An engine including the compressor has in downstream serial flow relationship from the compressor a combustor and a high pressure turbine drivingly connected to the compressor by a high pressure shaft.
Matrix calculus for axially symmetric polarized beam.
Matsuo, Shigeki
2011-06-20
The Jones calculus is a well known method for analyzing the polarization of a fully polarized beam. It deals with a beam having spatially homogeneous polarization. In recent years, axially symmetric polarized beams, where the polarization is not homogeneous in its cross section, have attracted great interest. In the present article, we show the formula for the rotation of beams and optical elements on the angularly variant term-added Jones calculus, which is required for analyzing axially symmetric beams. In addition, we introduce an extension of the Jones calculus: use of the polar coordinate basis. With this calculus, the representation of some angularly variant beams and optical elements are simplified and become intuitive. We show definitions, examples, and conversion formulas between different notations.
Photoelastic analysis of stresses transmitted by complete dentures lined with hard or soft liners.
Pereira, Izabella P; Consani, Rafael L X; Mesquita, Marcelo F; Nóbilo, Mauro A A
2015-10-01
Stresses transmitted on the alveolar bone ridge by lined conventional complete mandibular dentures can decrease the bone absorption level. The aim of this in vitro study was to evaluate the stresses induced on the alveolar bone ridge of lined conventional complete mandibular dentures by using photoelastic analysis. One maxillary and three mandibular conventional dentures were developed for the following treatments: 1 - Unlined denture (control), 2 - Denture lined with resin-based material, and 3 - Denture lined with silicone-based material. The photoelastic analysis took place with the dentures in the position of maximum intercuspation, and the mandibular photoelastic models were axially loaded with 10 kgf (98 N). Unlined denture (control) presented stresses along the model, especially on the anterior and left lateral sides with less stresses on the right side. On the left lateral side, the denture base lined with resin-based material demonstrated similar stresses to that of the control; however, lower stresses occurred in the premolar and retromolar regions. Denture bases lined with silicone-based material showed decreased fringe orders and homogeneous distribution of induced stresses. Both lined dentures exhibited lower stresses when compared to unlined dentures. Silicone-based material provided a more homogeneous distribution of stresses. Copyright © 2015 Elsevier B.V. All rights reserved.
Consistent formulation of the spacelike axial gauge
Burnel, A.; Van der Rest-Jaspers, M.
1983-12-15
The usual formulation of the spacelike axial gauge is afflicted with the difficulty that the metric is indefinite while no ghost is involved. We solve this difficulty by introducing a ghost whose elimination is such that the metric becomes positive for physical states. The technique consists in the replacement of the gauge condition nxA = 0 by the weaker one partial/sub 0/nxAroughly-equal0.
Transonic Axial Splittered Rotor Tandem Stator Stage
2016-12-01
compressor rotor was designed incorporating a splitter vane between the principal blades . Historical experiments conducted by Dr. Arthur J...conventional rotor design . The stage is composed of the rotor and stator. The flow of the air passing through the rotor is turned, and the flow is required...derived results achieved the best blade geometry for design continuation. The best circumferential and axial placement for the splitter blade was
Multimode interaction in axially excited cylindrical shells
2014-01-01
Cylindrical shells exhibit a dense frequency spectrum, especially near the lowest frequency range. In addition, due to the circumferential symmetry, frequencies occur in pairs. So, in the vicinity of the lowest natural frequencies, several equal or nearly equal frequencies may occur, leading to a complex dynamic behavior. So, the aim of the present work is to investigate the dynamic behavior and stability of cylindrical shells under axial forcing with multiple equal or nearly equal natural fr...
Axial flux permanent magnet brushless machines
Gieras, Jacek F; Kamper, Maarten J
2008-01-01
Axial Flux Permanent Magnet (AFPM) brushless machines are modern electrical machines with a lot of advantages over their conventional counterparts. They are being increasingly used in consumer electronics, public life, instrumentation and automation system, clinical engineering, industrial electromechanical drives, automobile manufacturing industry, electric and hybrid electric vehicles, marine vessels and toys. They are also used in more electric aircrafts and many other applications on larger scale. New applications have also emerged in distributed generation systems (wind turbine generators
Enhancement of Optical Coherence Tomography Axial Resolution by Spectral Shaping
孙汕; 郭继华; 高湔松; 薛平
2002-01-01
We propose a new method of changing the spectrum shape to improve the axial resolution of optical coherencetomography (OCT). Theoretical analysis shows that certain spectral shaping can shorten the coherence length.Comparisons of the simulation and experimental measurements of spectral shape and axial resolution of OCTare given, showing that the axial resolution of OCT is enhanced by a factor of 1.4.
EFFECTIVE STRESS AND STRAIN IN FINITE DEFORMATION
周喆; 秦伶俐; 黄文彬; 王红卫
2004-01-01
Whether the concept of effective stress and strain in elastic-plastic theory is still valid under the condition of finite deformation was mainly discussed. The uni-axial compression experiments in plane stress and plane strain states were chosen for study. In the two kinds of stress states, the stress- strain curve described by logarithm strain and rotated Kirchhoff stress matches the experiments data better than the curves defined by other stressstrain description.
Direct optical nanoscopy with axially localized detection
Bourg, N.; Mayet, C.; Dupuis, G.; Barroca, T.; Bon, P.; Lécart, S.; Fort, E.; Lévêque-Fort, S.
2015-09-01
Evanescent light excitation is widely used in super-resolution fluorescence microscopy to confine light and reduce background noise. Here, we propose a method of exploiting evanescent light in the context of emission. When a fluorophore is located in close proximity to a medium with a higher refractive index, its near-field component is converted into light that propagates beyond the critical angle. This so-called supercritical-angle fluorescence can be captured using a high-numerical-aperture objective and used to determine the axial position of the fluorophore with nanometre precision. We introduce a new technique for three-dimensional nanoscopy that combines direct stochastic optical reconstruction microscopy (dSTORM) with dedicated detection of supercritical-angle fluorescence emission. We demonstrate that our approach of direct optical nanoscopy with axially localized detection (DONALD) typically yields an isotropic three-dimensional localization precision of 20 nm within an axial range of ∼150 nm above the coverslip.
Axial gravity, massless fermions and trace anomalies
Bonora, L.; Cvitan, M.; Prester, P. Dominis; Pereira, A. Duarte; Giaccari, S.; Štemberga, T.
2017-08-01
This article deals with two main topics. One is odd parity trace anomalies in Weyl fermion theories in a 4d curved background, the second is the introduction of axial gravity. The motivation for reconsidering the former is to clarify the theoretical background underlying the approach and complete the calculation of the anomaly. The reference is in particular to the difference between Weyl and massless Majorana fermions and to the possible contributions from tadpole and seagull terms in the Feynman diagram approach. A first, basic, result of this paper is that a more thorough treatment, taking account of such additional terms and using dimensional regularization, confirms the earlier result. The introduction of an axial symmetric tensor besides the usual gravitational metric is instrumental to a different derivation of the same result using Dirac fermions, which are coupled not only to the usual metric but also to the additional axial tensor. The action of Majorana and Weyl fermions can be obtained in two different limits of such a general configuration. The results obtained in this way confirm the previously obtained ones.
Bessel beam CARS of axially structured samples
Heuke, Sandro; Zheng, Juanjuan; Akimov, Denis; Heintzmann, Rainer; Schmitt, Michael; Popp, Jürgen
2015-01-01
We report about a Bessel beam CARS approach for axial profiling of multi-layer structures. This study presents an experimental implementation for the generation of CARS by Bessel beam excitation using only passive optical elements. Furthermore, an analytical expression is provided describing the generated anti-Stokes field by a homogeneous sample. Based on the concept of coherent transfer functions, the underling resolving power of axially structured geometries is investigated. It is found that through the non-linearity of the CARS process in combination with the folded illumination geometry continuous phase-matching is achieved starting from homogeneous samples up to spatial sample frequencies at twice of the pumping electric field wave. The experimental and analytical findings are modeled by the implementation of the Debye Integral and scalar Green function approach. Finally, the goal of reconstructing an axially layered sample is demonstrated on the basis of the numerically simulated modulus and phase of the anti-Stokes far-field radiation pattern. PMID:26046671
Golimumab for the treatment of axial spondyloarthritis.
Gelfer, Gita; Perry, Lisa; Deodhar, Atul
2016-01-01
Axial spondyloarthritis (axSpA) is a chronic, immune-mediated inflammatory disease of the axial skeleton that includes ankylosing spondylitis (AS) and non-radiographic axial spondyloarthritis (nr-axSpA). Patients with AS experience chronic pain due to sacroiliac joint and spinal inflammation, and may develop spinal ankylosing with syndesmophyte formation. Tumor necrosis factor α inhibitors (TNFi) have shown promise in the management of AS and axSpA by targeting the underlying inflammatory process, and providing symptomatic relief. Whether they alter the progression of the disease is uncertain. Golimumab is a fully human IgG1 monoclonal antibody that targets and downregulates the pro-inflammatory cytokine TNF-α. The use of golimumab has been shown to reduce the signs and symptoms of axSpA as well as improve patient function and quality reported outcomes. This review focuses on the biological rationale and the results of clinical trials with golimumab for the treatment of axSpA.
Dynamic control of knee axial deformities
E. E. Malyshev
2013-01-01
Full Text Available The authors have evaluated the clinical examination of the patients with axial malalignments in the knee by the original method and device which was named varovalgometer. The measurements were conducted by tension of the cord through the spina iliaca anterior superior and the middle of the lower pole of patella. The deviation of the center of the ankle estimated by metal ruler which was positioned perpendicular to the lower leg axis on the level of the ankle joint line. The results of comparison of our method and computer navigation in 53 patients during the TKA show no statistically significant varieties but they differ by average 5° of valgus in clinical examination in comparison with mechanical axis which was identified by computer navigation. The dynamic control of axial malalignment can be used in clinical practice for estimation of the results of treatment of pathology with axial deformities in the knee; for the control of reduction and secondary displacement of the fractures around the knee; for assessment of instability; in planning of correctional osteotomies and intraoperative control of deformity correction; for estimation of Q angle in subluxation and recurrent dislocation of patella; in planning of TKA; during the growth of child it allows to assess the progression of deformity.
Yoganandan, Narayan; Stemper, Brian D; Pintar, Frank A; Baisden, Jamie L; Shender, Barry S; Paskoff, Glenn
2008-03-01
In contrast to clinical studies wherein loading magnitudes are indeterminate, experiments permit controlled and quantifiable moment applications, record kinematics in multiple planes, and allow derivation of moment-angulation corridors. Axial and coronal moment-angulation corridors were determined at every level of the subaxial cervical spine, expressed as logarithmic functions, and level-specificity of range of motion and neutral zones were evaluated. segmental primary axial and coupled coronal motions do not vary by level. Although it is known that cervical spine responses are coupled, segment-specific corridors of axial and coronal kinematics under axial twisting moments from healthy normal spines are not reported. Ten human cadaver columns (23-44 years, mean: 34 +/- 6.8) were fixed at the ends and targets were inserted to each vertebra to obtain kinematics in axial and coronal planes. The columns were subjected to pure axial twisting moments. Range of motion and neutral zone for primary-axial and coupled-coronal rotation components were determined at each spinal level. Data were analyzed using factorial analysis of variance. Moment-rotation angulations were expressed using logarithmic functions, and mean +/-1 standard deviation corridors were derived at each level for both components. Moment-angulations responses were nonlinear. Each segmental curve for both components was well represented by a logarithmic function (r2 > 0.95). Factorial analysis of variance indicated that the biomechanical metrics are spinal level-specific (P specific responses. The presentation of moment-angulation corridors for both metrics forms a dataset for the normal population. These segment-specific nonlinear corridors may help clinicians assess dysfunction or instability. These data will assist mathematical models of the spine in improved validation and lead to efficacious design of stabilizing systems.
Zhang, Chaobi; Chen, Jian Yun; Xu, Qiang; Li, Jing [School of Civil and Hydraulic Engineering, Dalian University of Technology, Dalian (China)
2015-08-15
In order to analyze the mechanical properties of two-way different configurations of prestressed concrete members subjected to axial loading, a finite element model based on the nuclear power plant containments is demonstrated. This model takes into account the influences of different principal stress directions, the uniaxial or biaxial loading, and biaxial loading ratio. The displacement-controlled load is applied to obtain the stress-strain response. The simulated results indicate that the differences of principal stress axes have great effects on the stress-strain response under uniaxial loading. When the specimens are subjected to biaxial loading, the change trend of stress with the increase of loading ratio is obviously different along different layout directions. In addition, correlation experiments and finite element analyses were conducted to verify the validity and reliability of the analysis in this study.
Din, Ghiyas Ud [Department of Nuclear Engineering, Pakistan Institute of Engineering and Applied Sciences (PIEAS), P.O. Nilore, Islamabad (Pakistan); Isotope Applications Division, Pakistan Institute of Nuclear Science and Technology (PINSTECH), P.O. Nilore, Islamabad (Pakistan)], E-mail: fac192@pieas.edu.pk; Chughtai, Imran Rafiq; Inayat, Mansoor Hameed [Department of Chemical and Materials Engineering, Pakistan Institute of Engineering and Applied Sciences (PIEAS), P.O. Nilore, Islamabad (Pakistan); Khan, Iqbal Hussain [Isotope Applications Division, Pakistan Institute of Nuclear Science and Technology (PINSTECH), P.O. Nilore, Islamabad (Pakistan)
2008-12-15
Axial dispersion, holdup and slip velocity of dispersed phase have been investigated for a range of dispersed and continuous phase superficial velocities in a pulsed sieve plate extraction column using radiotracer residence time distribution (RTD) analysis. Axial dispersion model (ADM) was used to simulate the hydrodynamics of the system. It has been observed that increase in dispersed phase superficial velocity results in a decrease in its axial dispersion and increase in its slip velocity while its holdup increases till a maximum asymptotic value is achieved. An increase in superficial velocity of continuous phase increases the axial dispersion and holdup of dispersed phase until a maximum value is obtained, while slip velocity of dispersed phase is found to decrease in the beginning and then it increases with increase in superficial velocity of continuous phase.
Effect of axial force on the performance of micromachined vibratory rate gyroscopes.
Hou, Zhanqiang; Xiao, Dingbang; Wu, Xuezhong; Dong, Peitao; Chen, Zhihua; Niu, Zhengyi; Zhang, Xu
2011-01-01
It is reported in the published literature that the resonant frequency of a silicon micromachined gyroscope decreases linearly with increasing temperature. However, when the axial force is considerable, the resonant frequency might increase as the temperature increases. The axial force is mainly induced by thermal stress due to the mismatch between the thermal expansion coefficients of the structure and substrate. In this paper, two types of micromachined suspended vibratory gyroscopes with slanted beams were proposed to evaluate the effect of the axial force. One type was suspended with a clamped-free (C-F) beam and the other one was suspended with a clamped-clamped (C-C) beam. Their drive modes are the bending of the slanted beam, and their sense modes are the torsion of the slanted beam. The relationships between the resonant frequencies of the two types were developed. The prototypes were packaged by vacuum under 0.1 mbar and an analytical solution for the axial force effect on the resonant frequency was obtained. The temperature dependent performances of the operated mode responses of the micromachined gyroscopes were measured. The experimental values of the temperature coefficients of resonant frequencies (TCF) due to axial force were 101.5 ppm/°C for the drive mode and 21.6 ppm/°C for the sense mode. The axial force has a great influence on the modal frequency of the micromachined gyroscopes suspended with a C-C beam, especially for the flexure mode. The quality factors of the operated modes decreased with increasing temperature, and changed drastically when the micromachined gyroscopes worked at higher temperatures.
Effect of Axial Force on the Performance of Micromachined Vibratory Rate Gyroscopes
Zhengyi Niu
2010-12-01
Full Text Available It is reported in the published literature that the resonant frequency of a silicon micromachined gyroscope decreases linearly with increasing temperature. However, when the axial force is considerable, the resonant frequency might increase as the temperature increases. The axial force is mainly induced by thermal stress due to the mismatch between the thermal expansion coefficients of the structure and substrate. In this paper, two types of micromachined suspended vibratory gyroscopes with slanted beams were proposed to evaluate the effect of the axial force. One type was suspended with a clamped-free (C-F beam and the other one was suspended with a clamped-clamped (C-C beam. Their drive modes are the bending of the slanted beam, and their sense modes are the torsion of the slanted beam. The relationships between the resonant frequencies of the two types were developed. The prototypes were packaged by vacuum under 0.1 mbar and an analytical solution for the axial force effect on the resonant frequency was obtained. The temperature dependent performances of the operated mode responses of the micromachined gyroscopes were measured. The experimental values of the temperature coefficients of resonant frequencies (TCF due to axial force were 101.5 ppm/°C for the drive mode and 21.6 ppm/°C for the sense mode. The axial force has a great influence on the modal frequency of the micromachined gyroscopes suspended with a C-C beam, especially for the flexure mode. The quality factors of the operated modes decreased with increasing temperature, and changed drastically when the micromachined gyroscopes worked at higher temperatures.
Study on Constitutive Model for Root System of Korshinsk peashrub in Axial Tension
Guo-jian Feng
2015-12-01
Full Text Available Constitutive model for root system of Korshinsk peashrub (Caragana korshinskii Kom. in axial tension is an important tool for analyzing the mechanism of soil reinforcement of root system. This model enables a mechanical analysis on strength and deformation of root system and root-soil complex. We carried out axial tension test of root system of Korshinsk peashrub in this paper and discussed the stress-strain relation. Based on the experimental results, the constitutive model for root system of Korshinsk peashrub in axial tension was established. Results showed that: (1 When the strain was smaller than 4%, the stress-strain relation was linear for single root, corresponding to linear elastic deformation; when the strain was larger than 4%, the single root underwent plastic deformation; (2 Elastic modulus of the root system was related to root diameter by a power function. The smaller the root diameter, the higher the elastic modulus was; (3 Root diameter was related to the ultimate tensile strength of root also by a power function. The smaller the root diameter, the higher the ultimate tensile strength of root was; (4 The tensile stress-strain curve of the root system divided into ascending segment and descending segment, which was fitted by parabola and curvilinear model, respectively.
Gravesen, F H; McMahon, B P; Drewes, A M; Gregersen, H
2008-03-01
The oesophagus serves to transport food and fluid from the pharynx to the stomach. Oesophageal function is usually evaluated by means of manometry which is a proxy of the force in the radial direction. However, force measurements in the axial direction will provide a better measure of oesophageal transport function. The aim of this study was to develop a probe based on electrical impedance measurements to quantify the axial force generated by oesophageal contractions, i.e. probe elongation was associated with the axial force. Calibration with weights up to 200 g was done. The dispersion, creep, temperature and bending dependence were studied at the bench. Subsequently, the probe was tested in vivo in a healthy human volunteer. The probe showed good reproducibility and the dispersion was <0.04. Some dependence on temperature, creep and bending was found. Interpolation of the calibration curves made it possible to compensate for temperature fluctuations. The maximum deviation was 6.1 +/- 3.7% at loads of 50 g. The influence of creep showed a maximum net creep of 6.1 g after 8 s. The swallowed bolus size correlated with the axial force measurements (P = 0.038) but not with manometric measurements. In conclusion, the new technique measures axial force in the oesophagus and may in the future provide valuable information about oesophageal function.
Maximum Genus of Strong Embeddings
Er-ling Wei; Yan-pei Liu; Han Ren
2003-01-01
The strong embedding conjecture states that any 2-connected graph has a strong embedding on some surface. It implies the circuit double cover conjecture: Any 2-connected graph has a circuit double cover.Conversely, it is not true. But for a 3-regular graph, the two conjectures are equivalent. In this paper, a characterization of graphs having a strong embedding with exactly 3 faces, which is the strong embedding of maximum genus, is given. In addition, some graphs with the property are provided. More generally, an upper bound of the maximum genus of strong embeddings of a graph is presented too. Lastly, it is shown that the interpolation theorem is true to planar Halin graph.
Remizov, Ivan D
2009-01-01
In this note, we represent a subdifferential of a maximum functional defined on the space of all real-valued continuous functions on a given metric compact set. For a given argument, $f$ it coincides with the set of all probability measures on the set of points maximizing $f$ on the initial compact set. This complete characterization lies in the heart of several important identities in microeconomics, such as Roy's identity, Sheppard's lemma, as well as duality theory in production and linear programming.
Hongwei MA; Baihe LI
2008-01-01
This paper presents a numerical investigation of effects of axial non-uniform tip clearances on the aerodynamic performance of a transonic axial compressor rotor (NASA Rotor 37). The three-dimensional steady flow field within the rotor passage was simulated with the datum tip clearance of 0.356 mm at the design wheel speed of 17188.7 rpm. The simulation results are well consistent with the measurement results, which verified the numeri-cal method. Then the three-dimensional steady flow field within the rotor passage was simulated respectively with different axial non-uniform tip clearances. The calculation results showed that optimal axial non-uniform tip clearances could improve the compressor performance, while the efficiency and the pressure ratio of the com-pressor were increased. The flow mechanism is that the axial non-uniform tip clearance can weaken the tip leak-age vortex, blow down low-energy fluids in boundary layers and reduce both flow blockage and tip loss.
Lee, Ryan K.L.; Griffith, James F.; Ng, Alex W.H.; Law, Eric K.C. [The Chinese University of Hong Kong, Department of Imaging and Interventional Radiology, Prince Of Wales Hospital, Hong Kong (China); Tse, W.L.; Wong, Clara W.Y.; Ho, P.C. [The Chinese University of Hong Kong, Department of Orthopedics and Traumatology, Prince Of Wales Hospital, Hong Kong (China)
2017-03-15
To compare axial and oblique axial planes on MR arthrography (MRA) and multidetector CT arthrography (CTA) to evaluate dorsal and volar parts of scapholunate (SLIL) and lunotriquetral interosseous (LTIL) ligaments. Nine cadaveric wrists of five male subjects were studied. The visibility of dorsal and volar parts of the SLIL and LTIL was graded semi-quantitatively (good, intermediate, poor) on MRA and CTA. The presence of a ligament tear was determined on arthrosocopy and sensitivity, specificity and accuracy of tear detection were calculated. Oblique axial imaging was particularly useful for delineating dorsal and volar parts of the LTIL on MRA with overall 'good' visibility increased from 11 % to 78 %. The accuracy of MRA and CTA in revealing SLIL and LTIL tear was higher using the oblique axial plane. The overall accuracy for detecting SLIL tear on CTA improved from 94 % to 100 % and from 89 % to 94 % on MRA; the overall accuracy of detecting LTIL tear on CTA improved from 89 % to 100 % and from 72 % to 89 % on MRA Oblique axial imaging during CT and MR arthrography improves detection of tears in the dorsal and volar parts of both SLIL and LTIL. (orig.)
The Testability of Maximum Magnitude
Clements, R.; Schorlemmer, D.; Gonzalez, A.; Zoeller, G.; Schneider, M.
2012-12-01
Recent disasters caused by earthquakes of unexpectedly large magnitude (such as Tohoku) illustrate the need for reliable assessments of the seismic hazard. Estimates of the maximum possible magnitude M at a given fault or in a particular zone are essential parameters in probabilistic seismic hazard assessment (PSHA), but their accuracy remains untested. In this study, we discuss the testability of long-term and short-term M estimates and the limitations that arise from testing such rare events. Of considerable importance is whether or not those limitations imply a lack of testability of a useful maximum magnitude estimate, and whether this should have any influence on current PSHA methodology. We use a simple extreme value theory approach to derive a probability distribution for the expected maximum magnitude in a future time interval, and we perform a sensitivity analysis on this distribution to determine if there is a reasonable avenue available for testing M estimates as they are commonly reported today: devoid of an appropriate probability distribution of their own and estimated only for infinite time (or relatively large untestable periods). Our results imply that any attempt at testing such estimates is futile, and that the distribution is highly sensitive to M estimates only under certain optimal conditions that are rarely observed in practice. In the future we suggest that PSHA modelers be brutally honest about the uncertainty of M estimates, or must find a way to decrease its influence on the estimated hazard.
Alternative Multiview Maximum Entropy Discrimination.
Chao, Guoqing; Sun, Shiliang
2016-07-01
Maximum entropy discrimination (MED) is a general framework for discriminative estimation based on maximum entropy and maximum margin principles, and can produce hard-margin support vector machines under some assumptions. Recently, the multiview version of MED multiview MED (MVMED) was proposed. In this paper, we try to explore a more natural MVMED framework by assuming two separate distributions p1( Θ1) over the first-view classifier parameter Θ1 and p2( Θ2) over the second-view classifier parameter Θ2 . We name the new MVMED framework as alternative MVMED (AMVMED), which enforces the posteriors of two view margins to be equal. The proposed AMVMED is more flexible than the existing MVMED, because compared with MVMED, which optimizes one relative entropy, AMVMED assigns one relative entropy term to each of the two views, thus incorporating a tradeoff between the two views. We give the detailed solving procedure, which can be divided into two steps. The first step is solving our optimization problem without considering the equal margin posteriors from two views, and then, in the second step, we consider the equal posteriors. Experimental results on multiple real-world data sets verify the effectiveness of the AMVMED, and comparisons with MVMED are also reported.
Sharf Abdusalam M.
2014-03-01
Full Text Available In the oil and gas industries, understanding the behaviour of a flow through an annulus gap in a vertical position, whose outer wall is stationary whilst the inner wall rotates, is a significantly important issue in drilling wells. The main emphasis is placed on experimental (using an available rig and computational (employing CFD software investigations into the effects of the rotation speed of the inner pipe on the axial velocity profiles. The measured axial velocity profiles, in the cases of low axial flow, show that the axial velocity is influenced by the rotation speed of the inner pipe in the region of almost 33% of the annulus near the inner pipe, and influenced inversely in the rest of the annulus. The position of the maximum axial velocity is shifted from the centre to be nearer the inner pipe, by increasing the rotation speed. However, in the case of higher flow, as the rotation speed increases, the axial velocity is reduced and the position of the maximum axial velocity is skewed towards the centre of the annulus. There is a reduction of the swirl velocity corresponding to the rise of the volumetric flow rate.
Lei Cao
2016-01-01
Full Text Available Clearance flows in the sidewall gaps of centrifugal pumps are unsteady as well as main flows in the volute casing and impeller, which may cause vibration and noise, and the corresponding pressure fluctuations are related to the axial clearance size. In this paper, unsteady numerical simulations were conducted to predict the unsteady flows within the entire flow passage of a centrifugal pump operating in the design condition. Pressure fluctuation characteristics in the volute casing, impeller, and sidewall gaps were investigated with three axial clearance sizes. Results show that an axial clearance variation affects the pressure fluctuation characteristics in each flow domain by different degree. The greatest pressure fluctuation occurs at the blade pressure surface and is almost not influenced by the axial clearance variation which has a certainly effect on the pressure fluctuation characteristics around the tongue. The maximum pressure fluctuation amplitude in the sidewall gaps is larger than that in the volute casing, and different spectrum characteristics show up in the three models due to the interaction between the clearance flow and the main flow as well as the rotor-stator interaction. Therefore, clearance flow should be taken into consideration in the hydraulic design of centrifugal pumps.
Dilipkumar Bhanudasji Alone
2014-01-01
Full Text Available This paper presents experimental results of a single stage transonic axial flow compressor coupled with low porosity bend skewed casing treatment. The casing treatment has a plenum chamber above the bend slots. The depth of the plenum chamber is varied to understand its impact on the performance of compressor stage. The performance of the compressor stage is evaluated for casing treatment and plenum chamber configurations at two axial locations of 20% and 40%. Experimental results reveal that the stall margin of the compressor stage increases with increase in the plenum chamber volume. Hot-wire measurements show significant reduction in the turbulence intensity with increase in the plenum chamber volume compared to that with the solid casing at the stall condition. At higher operating speeds of 80% and at 20% axial coverage, the stall margin of the compressor increases by 20% with half and full plenum depth. The improvement in the peak stage efficiency observed is 4.6% with half plenum configuration and 3.34% with the full plenum configuration. The maximum improvement in the stall margin of 29.16% is obtained at 50% operating speed with full plenum configurations at 40% axial coverage.
Three-dimensional model and simulation of vacuum arcs under axial magnetic fields
Wang, Lijun; Jia, Shenli; Zhou, Xin; Wang, Haijing; Shi, Zongqian
2012-01-01
In this paper, a three-dimensional (3d) magneto-hydro-dynamic (MHD) model of axial magnetic field vacuum arcs (AMFVAs) is established. Based on this model, AMFVAs are simulated and analyzed. Three-dimensional spatial distributions of many important plasma parameters and electric characteristics in AMFVAs can be obtained, such as ion number density, ion temperature, electron temperature, plasma pressure, current densities along different directions (x, y, and z), ion velocities along different directions, electric fields strength along different directions, and so on. Simulation results show that there exist significant spiral-shaped rotational phenomena in the AMFVAs, this kind of rotational phenomenon also can be verified by the many related experiments (AMFVAs photographs, especially for stronger AMF strength). For current simulation results of AMFVAs, the maximal rotational velocity at anode side is about 1100 m/s. Radial electric field is increased from arc center to arc edge; axial electric field is decreased from cathode side to anode side. Radial electric field at arc edge can be larger than axial electric field. Azimuthal electric field in most regions is much smaller than radial and axial electric field, but it can reach about 1.19 kV/m. Radial magnetic field is the smallest one compared with other components, it reaches to maximum value at the position near to anode, it can influence arc characteristics.
A geometrical model of vertical translation and alar ligament tension in atlanto-axial rotation.
Boszczyk, B M; Littlewood, A P; Putz, R
2012-08-01
biconvex atlanto-axial joints, reduces alar fibre elongation to 23.3%. The biconvex configuration of the atlanto-axial joints is an integral feature of the functionality of upper cervical spine as it allows gradual vertical translation of the atlas against the axis during axial rotation, with gradual tensing of the alar ligaments. Vertical translation on its own, however, does not explain the tolerance of the alar ligaments towards the maximum of 40° of rotation and is most likely synergistic with the effects of the coupled motion of occipitocervical extension during rotation.
Co-axial multicusp source for low axial energy spread ion beam production
Lee, Y; Leung, K N; Vujic, J L; Williams, M D; Zahir, N
1999-01-01
A co-axial multicusp ion source has been designed and tested. This source uses a new magnetic filter configuration. This magnetic filter is efficient in modifying the plasma potential distribution which can reduce the axial energy spread of the extracted ion beam. Energy spreads as low as 0.6 eV have been obtained. The electron temperature in this source has also been found to be about 0.1 eV. Furthermore, the new source configuration is capable of adjusting the radial plasma potential distribution which can improve the transverse ion energy, which results in a low beam emittance. The co-axial source can be used for a number of different applications such as ion projection lithography and radioactive ion beam projects.
Co-axial multicusp source for low axial energy spread ion beam production
Lee, Y. E-mail: yylee@lbl.gov; Gough, R.A.; Leung, K.N.; Vujic, J.; Williams, M.D.; Zahir, N
1999-09-01
A co-axial multicusp ion source has been designed and tested. This source uses a new magnetic filter configuration. This magnetic filter is efficient in modifying the plasma potential distribution which can reduce the axial energy spread of the extracted ion beam. Energy spreads as low as 0.6 eV have been obtained. The electron temperature in this source has also been found to be about 0.1 eV. Furthermore, the new source configuration is capable of adjusting the radial plasma potential distribution which can improve the transverse ion energy, which results in a low beam emittance. The co-axial source can be used for a number of different applications such as ion projection lithography and radioactive ion beam projects.
Co-axial multicusp source for low axial energy spread ion beam production
Lee, Y.; Gough, R. A.; Leung, K. N.; Vujic, J.; Williams, M. D.; Zahir, N.
1999-09-01
A co-axial multicusp ion source has been designed and tested. This source uses a new magnetic filter configuration. This magnetic filter is efficient in modifying the plasma potential distribution which can reduce the axial energy spread of the extracted ion beam. Energy spreads as low as 0.6 eV have been obtained. The electron temperature in this source has also been found to be about 0.1 eV. Furthermore, the new source configuration is capable of adjusting the radial plasma potential distribution which can improve the transverse ion energy, which results in a low beam emittance. The co-axial source can be used for a number of different applications such as ion projection lithography and radioactive ion beam projets.
Axial flow heat exchanger devices and methods for heat transfer using axial flow devices
Koplow, Jeffrey P.
2016-02-16
Systems and methods described herein are directed to rotary heat exchangers configured to transfer heat to a heat transfer medium flowing in substantially axial direction within the heat exchangers. Exemplary heat exchangers include a heat conducting structure which is configured to be in thermal contact with a thermal load or a thermal sink, and a heat transfer structure rotatably coupled to the heat conducting structure to form a gap region between the heat conducting structure and the heat transfer structure, the heat transfer structure being configured to rotate during operation of the device. In example devices heat may be transferred across the gap region from a heated axial flow of the heat transfer medium to a cool stationary heat conducting structure, or from a heated stationary conducting structure to a cool axial flow of the heat transfer medium.
Choi, Hyun Jin; Lee, Kyung Hee; Kim, Na Hee; Kim, Jun Ho; Hyun, In Young; Ryu, Jeong-Seon
2015-01-01
The purpose is to assess the value of adding coronal images for the identification of metastatic supraclavicular lymph nodes (LNs). Two radiologists reviewed axial images and combined axial and coronal images using thoracic computed tomography (CT) of 386 patients whose maximum standardized uptake value measured in a supraclavicular LN was ≥2.0 on a positron emission tomography. We compared sensitivity and agreement between readers before and after the addition of coronal images. For combined images, agreement was almost perfect (κ=0.982), and sensitivity was significantly higher (90.4%, Psupraclavicular metastasis. Copyright © 2015 Elsevier Inc. All rights reserved.
Cacti with maximum Kirchhoff index
Wang, Wen-Rui; Pan, Xiang-Feng
2015-01-01
The concept of resistance distance was first proposed by Klein and Randi\\'c. The Kirchhoff index $Kf(G)$ of a graph $G$ is the sum of resistance distance between all pairs of vertices in $G$. A connected graph $G$ is called a cactus if each block of $G$ is either an edge or a cycle. Let $Cat(n;t)$ be the set of connected cacti possessing $n$ vertices and $t$ cycles, where $0\\leq t \\leq \\lfloor\\frac{n-1}{2}\\rfloor$. In this paper, the maximum kirchhoff index of cacti are characterized, as well...
Generic maximum likely scale selection
Pedersen, Kim Steenstrup; Loog, Marco; Markussen, Bo
2007-01-01
The fundamental problem of local scale selection is addressed by means of a novel principle, which is based on maximum likelihood estimation. The principle is generally applicable to a broad variety of image models and descriptors, and provides a generic scale estimation methodology. The focus...... on second order moments of multiple measurements outputs at a fixed location. These measurements, which reflect local image structure, consist in the cases considered here of Gaussian derivatives taken at several scales and/or having different derivative orders....
Experimental Investigation of Axial and Beam-Riding Propulsive Physics with TEA CO2 laser
Kenoyer, D. A.; Salvador, I.; Myrabo, L. N.; Notaro, S. N.; Bragulla, P. W.
2010-10-01
A twin Lumonics K922M pulsed TEA CO2 laser system (pulse duration of approximately 100 ns FWHM spike, with optional 1 μs tail, depending upon laser gas mix) was employed to experimentally measure both axial thrust and beam-riding behavior of Type ♯200 lightcraft engines, using a ballistic pendulum and Angular Impulse Measurement Device (AIMD, respectively. Beam-riding forces and moments were examined along with engine thrust-vectoring behavior, as a function of: a) laser beam lateral offset from the vehicle axis of symmetry; b) laser pulse energy (˜12 to 40 joules); c) pulse duration (100 ns, and 1 μs); and d) engine size (97.7 mm to 161.2 mm). Maximum lateral momentum coupling coefficients (CM) of 75 N-s/MJ were achieved with the K922M laser whereas previous PLVTS laser (420 J, 18 μs duration) results reached only 15 N-s/MJ—an improvement of 5x. Maximum axial CM performance with the K922M reached 225 N-s/MJ, or about ˜3x larger than the lateral CM values. These axial CM results are sharply higher than the 120 N/MW previously reported for long pulse (e.g., 10-18 μs) CO2 electric discharge lasers.
Analysis and Calculation of Axial Stiffness of Tubular X-joints under Compression on Braces
QIU Guo-zhi; ZHAO Jin-cheng
2009-01-01
This paper introduces the influence factors of axial stiffness of tubular X-joints. The analysis model of tubular joints using plate and shell finite element method is also made. Systematic single-parameter analysis of tubular X-joints is performed using Ansys program. The influences of those factors, including ratio of brace diameter to chord diameter (β), ratio of chord diameter to twice chord thickness (γ), ratio of brace wall thickness to that of chord (τ), brace-to-chord intersection angle (θ), and chord stress ratio, ratio of another brace diameter to chord diameter, in-plane and out-of-plane moment of braces, etc., on stiffness of tubular X-joints are analyzed.Two non-dimensional parameters-joint axial stiffness factor ηN and axial force capacity factor ωN are proposed,and the relationship curve of the two factors is determined. Computational formulas of tubular X-joint axial stiffness are obtained by multi-element regression technology. The formulas can be used in design and analysis of steel tubular structures.
CFD Numerical Simulation of the Complex Turbulent Flow Field in an Axial-Flow Water Pump
Wan-You Li
2014-09-01
Full Text Available Further optimal design of an axial-flow water pump calls for a thorough recognition of the characteristics of the complex turbulent flow field in the pump, which is however extremely difficult to be measured using the up-to-date experimental techniques. In this study, a numerical simulation procedure based on computational fluid dynamics (CFD was elaborated in order to obtain the fully three-dimensional unsteady turbulent flow field in an axial-flow water pump. The shear stress transport (SST k-ω model was employed in the CFD calculation to study the unsteady internal flow of the axial-flow pump. Upon the numerical simulation results, the characteristics of the velocity field and pressure field inside the impeller region were discussed in detail. The established model procedure in this study may provide guidance to the numerical simulations of turbomachines during the design phase or the investigation of flow and pressure field characteristics and performance. The presented information can be of reference value in further optimal design of the axial-flow pump.
Axial Tomography from Digitized Real Time Radiography
Zolnay, A. S.; McDonald, W. M.; Doupont, P. A.; McKinney, R. L.; Lee, M. M.
1985-01-18
Axial tomography from digitized real time radiographs provides a useful tool for industrial radiography and tomography. The components of this system are: x-ray source, image intensifier, video camera, video line extractor and digitizer, data storage and reconstruction computers. With this system it is possible to view a two dimensional x-ray image in real time at each angle of rotation and select the tomography plane of interest by choosing which video line to digitize. The digitization of a video line requires less than a second making data acquisition relatively short. Further improvements on this system are planned and initial results are reported.
Ankylosing Spondylitis versus Nonradiographic Axial Spondyloarthritis
Glintborg, Bente; Sørensen, Inge J; Østergaard, Mikkel
2017-01-01
OBJECTIVE: To compare baseline disease activity and treatment effectiveness in biologic-naive patients with nonradiographic axial spondyloarthritis (nr-axSpA) and ankylosing spondylitis (AS) who initiate tumor necrosis factor inhibitor (TNFi) treatment and to study the role of potential confounders....../disease duration/TNFi-type/smoking/baseline disease activity) on TNFi adherence and response [e.g., Bath Ankylosing Spondylitis Activity Index (BASDAI) 50%/20 mm]. RESULTS: The study included 1250 TNFi-naive patients with axSpA (29% nr-axSpA, 50% AS, 21% lacked radiographs of sacroiliac joints). Patients...
Tunable axial potentials for atom chip waveguides
Stickney, James A; Imhof, Eric; Kroese, Bethany R; Crow, Jonathon A R; Olson, Spencer E; Squires, Matthew B
2014-01-01
We present a method for generating algebraically precise magnetic potentials along the axis of a cold atom waveguide near the surface of an atom chip. With a single chip design consisting of several wire pairs, various axial potentials can be created, including double wells, triple wells, and pure harmonic traps with suppression of higher order terms. We characterize the error along a harmonic trap between the expected algebraic form and magnetic field simulations and find excel- lent agreement, particularly at small displacements from the trap center. Finally, we demonstrate experimental control over the bottom fields of an asymmetric double well potential.
Cervical Spine Axial Rotation Goniometer Design
Emin Ulaş Erdem
2012-06-01
Full Text Available To evaluate the cervical spine rotation movement is quiet harder than other joints. Configuration and arrangement of current goniometers and devices is not always practic in clinics and some methods are quiet expensive. The cervical axial rotation goniometer designed by the authors is consists of five pieces (head apparatus, chair, goniometric platform, eye pads and camera. With this goniometer design a detailed evaluation of cervical spine range of motion can be obtained. Besides, measurement of "joint position sense" which is recently has rising interest in researches can be made practically with this goniometer.
Through-Flow Calculations in Axial Turbomachinery
1976-10-01
downstzega of the effective throat which is displaced upstream away from its kominal plano flow •_stion. Test data .-n nigh deflection blading tested in...AXIAL PIE ANGs-L;- VrELOC.I- T/Y SI~NG,’ c (,o nd) 2 .959 00 SO~ IS~N1RO iCoWLE tNJ\\\\ NJ\\v ON45l~5INi +U~SWC E.AAINZN5W~N3~6 8Lk5~ P-tO RM~ C -5A
Single Band Helical Antenna in Axial Mode
Parminder Singh
2012-11-01
Full Text Available Helical antennas have been widely used in a various useful applications, due to their low weight and low profile conformability, easy and cheap realization.Radiation properties of this antenna are examined both theoretically and experimentally. In this paper, an attempt has been made to investigate new helical antenna structure for Applications. CST MWS Software is used for the simulation and design calculations of the helical antennas. The axial ratio, return loss, VSWR, Directivity, gain, radiation pattern is evaluated. Using CST MWS simulation software proposed antenna is designed/simulated and optimized. The antenna exhibits a single band from 0 GHz to 3 GHz for GPS and several satellite applications
Economics and Maximum Entropy Production
Lorenz, R. D.
2003-04-01
Price differentials, sales volume and profit can be seen as analogues of temperature difference, heat flow and work or entropy production in the climate system. One aspect in which economic systems exhibit more clarity than the climate is that the empirical and/or statistical mechanical tendency for systems to seek a maximum in production is very evident in economics, in that the profit motive is very clear. Noting the common link between 1/f noise, power laws and Self-Organized Criticality with Maximum Entropy Production, the power law fluctuations in security and commodity prices is not inconsistent with the analogy. There is an additional thermodynamic analogy, in that scarcity is valued. A commodity concentrated among a few traders is valued highly by the many who do not have it. The market therefore encourages via prices the spreading of those goods among a wider group, just as heat tends to diffuse, increasing entropy. I explore some empirical price-volume relationships of metals and meteorites in this context.
Bougherara, H; Zdero, R; Mahboob, Z; Dubov, A; Shah, S; Schemitsch, E H
2010-10-01
This study proposes a novel hybrid total knee replacement (TKR) design to improve stress transfer to bone in the distal femur and, thereby, reduce stress shielding and consequent bone loss. Three-dimensional finite element (FE) models were developed for a standard and a hybrid TKR and validated experimentally. The Duracon knee system (Stryker Canada) was the standard TKR used for the FE models and for the experimental tests. The FE hybrid device was identical to the standard TKR, except that it had an interposing layer of carbon fibre-reinforced polyamide 12 lining the back of the metallic femoral component. A series of experimental surface strain measurements were then taken to validate the FE model of the standard TKR at 3000 N of axial compression and at 0 degreeof knee flexion. Comparison of surface strain values from FE analysis with experiments demonstrated good agreement, yielding a high Pearson correlation coefficient of R(2)= 0.94. Under a 3000N axial load and knee flexion angles simulating full stance (0O degree, heel strike (200 degrees, and toe off (600 degrees during normal walking gait, the FE model showed considerable changes in maximum Von Mises stress in the region most susceptible to stress shielding (i.e. the anterior region, just behind the flange of the femoral implant). Specifically, going from a standard to a hybrid TKR caused an increase in maximum stress of 87.4 per cent (O0 degree from 0.15 to 0.28 MPa), 68.3 per cent (200 degrees from 1.02 to 1.71 MPa), and 12.6 per cent (600 degrees from 2.96 to 3.33 MPa). This can potentially decrease stress shielding and subsequent bone loss and knee implant loosening. This is the first report to propose and biomechanically to assess a novel hybrid TKR design that uses a layer of carbon fibrereinforced polyamide 12 to reduce stress shielding.
AERODYNAMIC AND BLADING DESIGN OF MULTISTAGE AXIAL FLOW COMPRESSORS
Crouse, J. E.
1994-01-01
with fourth-degree polynomial functions of path distance from the maximum thickness point. Input to the aerodynamic and blading design program includes the annulus profile, the overall compressor mass flow, the pressure ratio, and the rotative speed. A number of input parameters are also used to specify and control the blade row aerodynamics and geometry. The output from the aerodynamic solution has an overall blade row and compressor performance summary followed by blade element parameters for the individual blade rows. If desired, the blade coordinates in the streamwise direction for internal flow analysis codes and the coordinates on plane sections through blades for fabrication drawings may be stored and printed. The aerodynamic and blading design program for multistage axial-flow compressors is written in FORTRAN IV for batch execution and has been implemented on an IBM 360 series computer with a central memory requirement of approximately 470K of 8 bit bytes. This program was developed in 1981.
Coherent and random apparent stresses in periodically unsteady flows
Kehoe, Anthony Byrd
1990-08-01
The transitional flow field downstream of a smooth, symmetrically constricted Sylgard pipe was measured with a two color, two component Laser Doppler Anemometer for both pulsatile and steady flows. Vibrations in the flow system were induced with an exciter/shaker and were monitored with an accelerator. The vibration has little effect on the value of the maximum axial and radial turbulence intensities. A frequency domain signal processing technique to separate the disturbance velocity into coherent and random components was modified to guarantee that the sum of the decomposed velocity components equaled the original disturbance velocity. Results of the velocity separation demonstrated that the velocity disturbances prior to turbulent transition consisted almost entirely of coherent velocity fluctuations. The maximum apparent shear stress was found to occur just after the turbulent transition and consisted almost entirely of the random component. The data suggest that if the absolute magnitude of the apparent stress is the determining factor in red blood cell destruction, then the coherent apparent stress is not a significant destruction mechanism. However, the exact mechanism in hemolysis are not identified.
LOAD CARRYING CAPABILITY OF LIQUID FILLED CYLINDRICAL SHELL STRUCTURES UNDER AXIAL COMPRESSION
QASIM H. SHAH
2011-08-01
Full Text Available Empty and water filled cylindrical Tin (Sn coated steel cans were loaded under axial compression at varying loading rates to study their resistance to withstand accidental loads. Compared to empty cans the water filled cans exhibit greater resistance to axially applied compression loads before a complete collapse. The time and load or stroke and load plots showed three significant load peaks related to three stages during loading until the cylinder collapse. First peak corresponds to the initial structural buckling of can. Second peak occurs when cylindrical can walls gradually come into full contact with water. The third peak shows the maximum load carrying capability of the structure where pressurized water deforms the can walls into curved shape until can walls fail under peak pressure. The collapse process of water filled cylindrical shell was further studied using Smooth Particle Hydrodynamics (SPH technique in LSDYNA. Load peaks observed in the experimental work were successfully simulated which substantiated the experimental work.
Single Rod Vibration in Axial Flow
Weichselbaum, Noah; Wang, Shengfu; Bardet, Philippe
2013-11-01
Fluid structure interaction of a single rod in axial flow is a coupled dynamical system present in many application including nuclear reactors, steam generators, and towed antenna arrays. Fluid-structure response can be quantified thanks to detailed experimental data where both structure and fluid responses are recorded. Such datum deepen understanding of the physics inherent to the system and provide high-dimensionality quantitative measurements to validate coupled structural and CFD codes with various level of complexity. In this work, single rods fixed on both ends in a concentric pipe, are subjected to an axial flow with Reynolds number based on hydraulic diameter of Re =4000. Rods of varying material stiffness and diameter are utilized in the experiment resulting in a range of dimensionless U between 0.5 and 1, where U = (ρA/EI)1/2uL. Experimental measurements of the velocity field around the rod are taken with PIV from time-resolved Nd:YLF laser and a high speed CMOS camera. Three-dimensional and temporal vibration and deflection of the rod is recorded with shadowgraphy utilizing two sets of pulsed high power LED and dedicated CMOS camera. Through integration of these two diagnostics, it is possible to reconstruct the full FSI domain providing unique validation data.
Multi-frequency axial transmission bone ultrasonometer.
Tatarinov, Alexey; Egorov, Vladimir; Sarvazyan, Noune; Sarvazyan, Armen
2014-07-01
The last decade has seen a surge in the development of axial transmission QUS (Quantitative UltraSound) technologies for the assessment of long bones using various modes of acoustic waves. The condition of cortical bones and the development of osteoporosis are determined by numerous mechanical, micro-structural, and geometrical or macro-structural bone properties like hardness, porosity and cortical thickness. Such complex manifestations of osteoporosis require the evaluation of multiple parameters with different sensitivities to the various properties of bone that are affected by the disease. This objective may be achieved by using a multi-frequency ultrasonic examination The ratio of the acoustic wavelength to the cortical thickness can be changed by varying the frequency of the ultrasonic pulse propagating through the long bone that results in the change in composition of the induced wave comprised of a set of numerous modes of guided, longitudinal, and surface acoustic waves. The multi-frequency axial transmission QUS method developed at Artann Laboratories (Trenton, NJ) is implemented in the Bone Ultrasonic Scanner (BUSS). In the current version of the BUSS, a train of ultrasonic pulses with 60, 100, 400, 800, and 1200 kHz frequencies is used. The developed technology was tested on a variety of bone phantoms simulating normal, osteopenic, and osteoporotic bones. The results of this study confirm the feasibility of the multi-frequency approach for the assessment of the processes leading to osteoporosis.
Piper, T; Piper, J
2012-09-01
Axial phase-darkfield-contrast (APDC) has been developed as an illumination technique in light microscopy which promises significant improvements and a higher variability in imaging of several transparent 'problem specimens'. With this method, a phase contrast image is optically superimposed on an axial darkfield image so that a partial image based on the principal zeroth order maximum (phase contrast) interferes with an image, which is based on the secondary maxima (axial darkfield). The background brightness and character of the resulting image can be continuously modulated from a phase contrast-dominated to a darkfield-dominated character. In order to achieve this illumination mode, normal objectives for phase contrast have to be fitted with an additional central light stopper needed for axial (central) darkfield illumination. In corresponding condenser light masks, a small perforation has to be added in the centre of the phase contrast providing light annulus. These light modulating elements are properly aligned when the central perforation is congruent with the objective's light stop and the light annulus is conjugate with the phase ring. The breadth of the condenser light annulus and thus the intensity of the phase contrast partial image can be regulated with the aperture diaphragm. Additional contrast effects can be achieved when both illuminating light components are filtered at different colours. In this technique, the axial resolution (depth of field) is significantly enhanced and the specimen's three-dimensional appearance is accentuated with improved clarity as well as fine details at the given resolution limit. Typical artefacts associated with phase contrast and darkfield illumination are reduced in our methods.
On the maximum mass of magnetised white dwarfs
Chatterjee, D; Chamel, N; Novak, J; Oertel, M
2016-01-01
We develop a detailed and self-consistent numerical model for extremely-magnetised white dwarfs, which have been proposed as progenitors of overluminous Type Ia supernovae. This model can describe fully-consistent equilibria of magnetic stars in axial symmetry, with rotation, general-relativistic effects and realistic equations of state (including electron-ion interactions and taking into account Landau quantisation of electrons due to the magnetic field). We study the influence of each of these ingredients onto the white dwarf structure and, in particular, on their maximum mass. We perform an extensive stability analysis of such objects, with their highest surface magnetic fields reaching $\\sim 10^{13}~G$ (at which point the star adopts a torus-like shape). We confirm previous speculations that although very massive strongly magnetised white dwarfs could potentially exist, the onset of electron captures and pycnonuclear reactions may severely limit their stability. Finally, the emission of gravitational wave...
LI Xiaohe; LI Zhijun; GAO Shang
2015-01-01
Objective:To analysis through the mouth atlanto-axial vertebral anterior plate fixation in finite element for the development of the segmental anterior fixation surgery and to provide the reference of inner plant im-provement. Methods:One case, male, 36 years old, 64 kg weight was randomly selected from January 2014 to our hospital to check no-skull - atlanto-axial vertebral disease . It was scanned by 0. 625 mm thin layer, Image data were rebuilted in the Mimics 16. 01 software, Pro/ENGINEER 4. 0 software was used to rebuilt atlanto-axial vertebral anterior plate, After reconstruction of steel screw 3 d model according to the classic through the mouth , the model was imported into Mimics 16. 01 and the model surface was meshed and material was assigned, The mod-el was forced 80 N vertical loading, the surface was applied 15 nm torque, to simulat three motion state example, forward bends, stretch, side-bending, The stress and deformation of screw and rod were measured. Results: At-lanto-axial vertebral three-dimensional reconstruction model were divided into 14 514 individual grid, 7 257 nodes, the model was loaded, The stress of upper screw root in bend was biggest (62. 34 ±5. 52) Mpa (F=73. 23, P<0. 05, the difference was statistically significant). A screw of the root and the top, lateral stress was the largest, respectively were (78. 42 ± 5. 5. 14) Mpa (F=112. 32, P<0. 05);(95. 48 ± 7. 12 Mpa (F=62. 32, P<0. 05), the difference was statistical significance; Under three different motion state and a screw root stress, Upper screw root stress in bending forward was greater than the lower (forward bends, stretch and lateral bending state , t value were 12. 2, 9. 23, 22. 98, P<0. 05, differences were statistically significant), and in the lateral current screw root stress was greater than the upper; In the same movement state, the top was greater than the root, the differences were statistically significant (forward bends, stretch and lateral bending state after
Objects of maximum electromagnetic chirality
Fernandez-Corbaton, Ivan
2015-01-01
We introduce a definition of the electromagnetic chirality of an object and show that it has an upper bound. The upper bound is attained if and only if the object is transparent for fields of one handedness (helicity). Additionally, electromagnetic duality symmetry, i.e. helicity preservation upon scattering, turns out to be a necessary condition for reciprocal scatterers to attain the upper bound. We use these results to provide requirements for the design of such extremal scatterers. The requirements can be formulated as constraints on the polarizability tensors for dipolar scatterers or as material constitutive relations. We also outline two applications for objects of maximum electromagnetic chirality: A twofold resonantly enhanced and background free circular dichroism measurement setup, and angle independent helicity filtering glasses.
Maximum mutual information regularized classification
Wang, Jim Jing-Yan
2014-09-07
In this paper, a novel pattern classification approach is proposed by regularizing the classifier learning to maximize mutual information between the classification response and the true class label. We argue that, with the learned classifier, the uncertainty of the true class label of a data sample should be reduced by knowing its classification response as much as possible. The reduced uncertainty is measured by the mutual information between the classification response and the true class label. To this end, when learning a linear classifier, we propose to maximize the mutual information between classification responses and true class labels of training samples, besides minimizing the classification error and reducing the classifier complexity. An objective function is constructed by modeling mutual information with entropy estimation, and it is optimized by a gradient descend method in an iterative algorithm. Experiments on two real world pattern classification problems show the significant improvements achieved by maximum mutual information regularization.
The strong maximum principle revisited
Pucci, Patrizia; Serrin, James
In this paper we first present the classical maximum principle due to E. Hopf, together with an extended commentary and discussion of Hopf's paper. We emphasize the comparison technique invented by Hopf to prove this principle, which has since become a main mathematical tool for the study of second order elliptic partial differential equations and has generated an enormous number of important applications. While Hopf's principle is generally understood to apply to linear equations, it is in fact also crucial in nonlinear theories, such as those under consideration here. In particular, we shall treat and discuss recent generalizations of the strong maximum principle, and also the compact support principle, for the case of singular quasilinear elliptic differential inequalities, under generally weak assumptions on the quasilinear operators and the nonlinearities involved. Our principal interest is in necessary and sufficient conditions for the validity of both principles; in exposing and simplifying earlier proofs of corresponding results; and in extending the conclusions to wider classes of singular operators than previously considered. The results have unexpected ramifications for other problems, as will develop from the exposition, e.g. two point boundary value problems for singular quasilinear ordinary differential equations (Sections 3 and 4); the exterior Dirichlet boundary value problem (Section 5); the existence of dead cores and compact support solutions, i.e. dead cores at infinity (Section 7); Euler-Lagrange inequalities on a Riemannian manifold (Section 9); comparison and uniqueness theorems for solutions of singular quasilinear differential inequalities (Section 10). The case of p-regular elliptic inequalities is briefly considered in Section 11.
Masaki Kawachi
2014-01-01
Full Text Available The effects of wavenumber and chirality on the axial compressive behavior and properties of wavy carbon nanotubes (CNTs with multiple Stone-Wales defects are investigated using molecular mechanics simulations with the adaptive intermolecular reactive empirical bond-order potential. The wavy CNTs are assumed to be point-symmetric with respect to their axial centers. It is found that the wavy CNT models, respectively, exhibit a buckling point and long wavelength buckling mode regardless of the wavenumbers and chiralities examined. It is also found that the wavy CNTs have nearly the same buckling stresses as their pristine straight counterparts.
Yijie Huang
2015-01-01
Full Text Available A new mechanical model for analysing the behaviour of axially loaded recycled aggregate concrete filled steel tubes (RACFSTs stub columns is presented in this study. The model is derived from the typical elastoplasticity, the nonlinear elastic mechanics, and the properties of materials. Based on the mechanical model, a novel numerical program is developed. The mechanical model and the numerical program are adopted to study the effect of recycled coarse aggregate (RCA replacement percentage on RACFST mechanical behaviour. The complete load-deformation relationship of specimens, the steel tube axial and circumferential stresses, and the performance of the confined core concrete and the variation of interaction are also investigated. The analytical results indicate that this model is able to capture the mechanical behaviour of RACFST. It is also found that the axial and circumferential stresses of steel tube change nonlinearly during the loading stages. It is concluded that the behaviour of the confined core concrete is significantly influenced by the confining pressure. The steel tube confinement could improve the mechanical behaviour of RAC effectively and the RCA replacement percentage slightly changes the response of core concrete. Finally, the relations between confined core concrete and confining pressure are analysed.
Multiaxial fatigue criterion based on parameters from torsion and axial S-N curve
M. Margetin
2016-07-01
Full Text Available Multiaxial high cycle fatigue is a topic that concerns nearly all industrial domains. In recent years, a great deal of recommendations how to address problems with multiaxial fatigue life time estimation have been made and a huge progress in the field has been achieved. Until now, however, no universal criterion for multiaxial fatigue has been proposed. Addressing this situation, this paper offers a design of a new multiaxial criterion for high cycle fatigue. This criterion is based on critical plane search. Damage parameter consists of a combination of normal and shear stresses on a critical plane (which is a plane with maximal shear stress amplitude. Material parameters used in proposed criterion are obtained from torsion and axial S-N curves. Proposed criterion correctly calculates life time for boundary loading condition (pure torsion and pure axial loading. Application of proposed model is demonstrated on biaxial loading and the results are verified with testing program using specimens made from S355 steel. Fatigue material parameters for proposed criterion and multiple sets of data for different combination of axial and torsional loading have been obtained during the experiment.
Study on the Axial Dispersion of Liquid in Column Flotation
周鵾; 曾爱武; 高长宝; 余国琮
2003-01-01
An experimental study on the axial dispersion of liquid was carried out in a 0.382-m-ID flotation column packed with different structured packings or free of packings. The correlations of axial Peclet numbers with the liquid and gas superficial Reynolds numbers were developed for various packings. Among the packings tested, it is found that in the column packed with 250Y or 350Y packings the axial dispersion is the lowest. The addition of frother can decrease the axial dispersion. By the simulation analysis of the one-dimension dispersion model of packed flotation column, it is found that small axial dispersion, high collection rate constant and low axial liquid velocity can increase the collection zone recovery.
Optimizing the top profile of a nanowire for maximum forward emission
Wang Dong-Lin; Yu Zhong-Yuan; Liu Yu-Min; Guo Xiao-Tao; Cao Gui; Feng Hao
2011-01-01
The optimal top structure of a nanowire quantum emitter single photon source is significant in improving performance.Based on the axial symmetry of a cylindrical nanowire,this paper optimizes the top profile of a nanowire for the maximum forward emission by combining the geometry projection method and the finite element method.The results indicate that the nanowire with a cambered top has the stronger emission in the forward direction,which is helpful to improve the photon collection efficiency.
Axial Compressive Strength of Foamcrete with Different Profiles and Dimensions
Othuman Mydin M.A.
2014-01-01
Full Text Available Lightweight foamcrete is a versatile material; primarily consist of a cement based mortar mixed with at least 20% volume of air. High flow ability, lower self-weight, minimal requirement of aggregate, controlled low strength and good thermal insulation properties are a few characteristics of foamcrete. Its dry densities, typically, is below 1600kg/m3 with compressive strengths maximum of 15MPa. The ASTM standard provision specifies a correction factor for concrete strengths of between 14 and 42MPa to compensate for the reduced strength when the aspect height-to-diameter ratio of specimen is less than 2.0, while the CEB-FIP provision specifically mentions the ratio of 150 x 300mm cylinder strength to 150 mm cube strength. However, both provisions requirements do not specifically clarify the applicability and/or modification of the correction factors for the compressive strength of foamcrete. This proposed laboratory work is intended to study the effect of different dimensions and profiles on the axial compressive strength of concrete. Specimens of various dimensions and profiles are cast with square and circular cross-sections i.e., cubes, prisms and cylinders, and to investigate their behavior in compression strength at 7 and 28 days. Hypothetically, compressive strength will decrease with the increase of concrete specimen dimension and concrete specimen with cube profile would yield comparable compressive strength to cylinder (100 x 100 x 100mm cube to 100dia x 200mm cylinder.
High-Frequency Axial Fatigue Test Procedures for Spectrum Loading
2016-07-20
REPORT NO: NAWCADPAX/TIM-2016/49 HIGH - FREQUENCY AXIAL FATIGUE TEST PROCEEDURES FOR SPECTRUM LOADING by David T. Rusk, AIR...OF THE NAVY NAVAL AIR WARFARE CENTER AIRCRAFT DIVISION PATUXENT RIVER, MARYLAND NAWCADPAX/TIM-2016/49 20 July 2016 HIGH - FREQUENCY AXIAL...Technical Information Memorandum 3. DATES COVERED 4. TITLE AND SUBTITLE High - Frequency Axial Fatigue Test Procedures for Spectrum Loading
A technique to determine a desired preparation axial inclination.
Parker, M Harry; Ivanhoe, John R; Blalock, John S; Frazier, Kevin B; Plummer, Kevin D
2003-10-01
The guidelines recommended in the literature for the convergence angle of a crown preparation vary from 3 to 24 degrees. There is a lack of guidelines on techniques to achieve a specific axial inclination. The purpose of this article was to present a practical technique, with a diamond rotary cutting instrument of known axial inclination, to determine the diamond rotary cutting instrument angulations required to achieve the desired axial inclination of a preparation.
Design and Test of a Transonic Axial Splittered Rotor
2015-06-15
AXIAL SPLITTERED ROTOR A new design procedure was developed that uses commercial-off-the-shelf software (MATLAB, SolidWorks , and ANSYS-CFX) for the...TRANSONIC AXIAL SPLITTERED ROTOR Report Title A new design procedure was developed that uses commercial-off-the-shelf software (MATLAB, SolidWorks , and...that uses commercial-off-the-shelf software (MATLAB, SolidWorks , and ANSYS-CFX) for the geometric rendering and analysis of a transonic axial
Rotordynamics of Turbine Labyrinth Seals with Rotor Axial Shifting
Jinxiang Xi; Rhode, David L.
2006-01-01
Rotors in high-performance steam turbines experience a significant axial shifting during starting and stopping processes due to thermal expansion, for example. This axial shifting could significantly alter the flow pattern and the flow-induced rotordynamic forces in labyrinth seals, which in turn, can considerably affect the rotor-seal system performance. This paper investigates the influence of the rotor axial shifting on leakage rate as well as rotordynamic forces in hi...
Pedersen, Niels Leergaard
2013-01-01
The state of stress in bolts and nuts with ISO metric thread design is examined and optimized. The assumed failure mode is fatigue so the applied preload and the load amplitude together with the stress concentrations define the connection strength. Maximum stress in the bolt is found at, the fillet...... under the head, at the thread start or at the thread root. To minimize the stress concentration shape optimization is applied....
Pedersen, Niels Leergaard
2013-01-01
The state of stress in bolts and nuts with ISO metric thread design is examined and optimized. The assumed failure mode is fatigue so the applied preload and the load amplitude together with the stress concentrations define the connection strength. Maximum stress in the bolt is found at, the fillet...... under the head, at the thread start or at the thread root. To minimize the stress concentration shape optimization is applied....
Kandouci Chahr-Eddine; Adjal Yassine
2014-01-01
This present paper deals with a mathematical description of linear axial and torsional vibrations. The normal and tangential stress tensor components produced by axial-torsional deformations and vibrations in the propeller and intermediate shafts, under the influence of propeller-induced static and variable hydrodynamic excitations are also studied. The transfer matrix method related to the constant coefficients of differential equation solutions is used. The advantage of the latter as compared with a well-known method of transfer matrix associated with state vector is the possibility of reducing the number of multiplied matrices when adjacent shaft segments have the same material properties and diameters. The results show that there is no risk of buckling and confirm that the strength of the shaft line depends on the value of the static tangential stresses which is the most important component of the stress tensor.
Bohnenstiehl, D. R.; Dziak, R. P.; Caplan-Auerbach, J.; Haxel, J. H.; Mann, M. E.; Pennington, C.; Weis, J.; Womack, N.; Levy, S.
2015-12-01
Tidal stress changes are known to modulate the timing of microearthquakes within many mid-ocean ridge volcanic systems. At Axial Volcano, located on the Juan de Fuca Ridge, earthquakes occur preferentially when volumetric extension peaks near times of low ocean tide. Autonomous ocean-bottom hydrophone (OBH, 2007-2011) and cabled ocean bottom seismometer (OBS, Nov. 2014-) data are used to quantify the strength of tidal triggering in time periods before the April 2011 and April 2015 eruptions at Axial Volcano. The mean percent excess at times of low ocean-tide is ~14% (16% std) in the four years prior to the 2011 eruption and ~18% (17% std) in the five months prior to the 2015 eruption. The sensitivity of earthquakes to tidal stress does not evolve systematically prior to either eruption; however, this pattern is disturbed by much larger stress changes associated with the onset of dike intrusion. Following dike injection and eruption, seismicity rates drop sharply. As seismicity rates continue to rise in the months following the 2015 eruption, real-time data available from the cabled OBS network will be used quantify temporal patterns in microearthquake activity as dike induced stresses are relaxed and the magma chamber inflates.
Gil, Christopher M.
1998-01-01
An experimental program to determine flow surfaces has been established and implemented for solution annealed and aged IN718. The procedure involved subjecting tubular specimens to various ratios of axial-torsional stress at temperatures between 23 and 649 C and measuring strain with a biaxial extensometer. Each stress probe corresponds to a different direction in stress space, and unloading occurs when a 30 microstrain (1 micro eplison = 10(exp -6) mm/mm) offset is detected. This technique was used to map out yield loci in axial-torsional stress space. Flow surfaces were determined by post-processing the experimental data to determine the inelastic strain rate components. Surfaces of constant inelastic strain rate (SCISRS) and surfaces of constant inelastic power (SCIPS) were mapped out in the axial-shear stress plane. The von Mises yield criterion appeared to closely fit the initial loci for solutioned IN718 at 23 C. However, the initial loci for solutioned IN718 at 371 and 454 C, and all of the initial loci for aged IN718 were offset in the compression direction. Subsequent loci showed translation, distortion, and for the case of solutioned IN718, a slight cross effect. Aged IN718 showed significantly more hardening behavior than solutioned IN718.
The axial ratio of hcp iron at the conditions of the Earth's inner core
Gannarelli, C M S; Gillian, M J
2004-01-01
We present ab initio calculations of the high-temperature axial c/a ratio of hexagonal-close-packed (hcp) iron at Earth's core pressures, in order to help interpret the observed seismic anisotropy of the inner core. The calculations are based on density functional theory, which is known to predict the properties of high-pressure iron with good accuracy. The temperature dependence of c/a is determined by minimising the Helmholtz free energy at fixed volume and temperature, with thermal contributions due to lattice vibrations calculated using harmonic theory. Anharmonic corrections to the harmonic predictions are estimated from calculations of the thermal average stress obtained from ab initio molecular dynamics simulations of hcp iron at the conditions of the inner core. We find a very gradual increase of axial ratio with temperature. This increase is much smaller than found in earlier calculations, but is in reasonable agreement with recent high-pressure, high-temperature diffraction measurements. This result...
A new design and computational fluid dynamics study of an implantable axial blood pump.
Koochaki, Mojtaba; Niroomand-Oscuii, Hanieh
2013-12-01
Considering small thoracic space, using implantable ventricular assist device requires reduction in a pump size. Among many available blood pumps, axial blood pumps have attracted greatly because of their small size. In this article, a new miniature axial blood pump has been designed and studied which can be easily implanted in the human body. In this design, the pump overall length decreased by a little increasing in the pump diameter, and new blade geometry is used to produce a streamlined, idealized, and nonobstructing blood flow path in the pump. By means of computational fluid dynamic, the flow pattern through the pump has been predicted and overall pump performance and efficiency has been computed. Also, to ensure a reliable VAD design, two methods for checking wall shear stress were used to confirm that this pump wouldn't cause serious blood damage.
Application of two-axial rolling for multicore Bi(2223)/Ag tapes
Kovác, P.; Husek, I.; Kopera, L.
1997-12-01
Multicore Ag-sheathed Bi(2223) tapes have been prepared by OPIT technique using the two-axial rolling deformation by active `Turk's head' roller. In comparison to wire drawing, the presented technique allows one to avoid the tensile stress during composite deformation and to increase the BSCCO-core density. A better homogeneity of filaments has been obtained by two-axial rolling. The transport critical current 0953-2048/10/12/025/img1 and its angular dependencies have been measured for single and 36 filament rectangular wires and tapes. Total tape widening influences the transport current density considerably but 0953-2048/10/12/025/img1 anisotropy at 0.1 T and 77 K is affected only slightly. Reduced 0953-2048/10/12/025/img1 anisotropy has been measured in a single core wire which has texturing of grains in two perpendicular rolling planes.
Strength and Deformation of Axially Loaded Fiber-Reinforced Polymer Sheet Confined Concrete Columns
李静; 钱稼茹; 蒋剑彪
2004-01-01
Experimental results of 29 axially loaded fiber-reinforced polymer sheet (FS) confined concrete columns and two reference plain concrete columns are introduced. Twenty four column specimens were confined with carbon fiber sheet (CFS) and five column specimens were hybrid confined with both CFS and glass fiber sheet (GFS). The influence of aspect ratio, FS material, initial axial force ratio, and FS confinement degree on the strength and deformation of columns were studied. Based on the experimental results, the equations of complete stress-strain curve of CFS confined concrete are proposed. These equations are suitable for the nonlinear analysis of square and rectangular section columns. Suggestions of applying FS to confine concrete columns are presented.
Modular functional organisation of the axial locomotor system in salamanders.
Cabelguen, Jean-Marie; Charrier, Vanessa; Mathou, Alexia
2014-02-01
Most investigations on tetrapod locomotion have been concerned with limb movements. However, there is compelling evidence that the axial musculoskeletal system contributes to important functions during locomotion. Adult salamanders offer a remarkable opportunity to examine these functions because these amphibians use axial undulations to propel themselves in both aquatic and terrestrial environments. In this article, we review the currently available biological data on axial functions during various locomotor modes in salamanders. We also present data showing the modular organisation of the neural networks that generate axial synergies during locomotion. The functional implication of this modular organisation is discussed.
Energy Dissipation in Sandwich Structures During Axial Compression
Urban, Jesper
2002-01-01
The purpose of this paper is to investigate the energy dissipation in sandwich structures during axial crushing. Axial crushing tests on six sandwich elements are described. The sandwich elements consist of a polyurethane core and E-glass/Polyester skin. The elements compare to full-scale structu......The purpose of this paper is to investigate the energy dissipation in sandwich structures during axial crushing. Axial crushing tests on six sandwich elements are described. The sandwich elements consist of a polyurethane core and E-glass/Polyester skin. The elements compare to full...
Maximum entropy production in daisyworld
Maunu, Haley A.; Knuth, Kevin H.
2012-05-01
Daisyworld was first introduced in 1983 by Watson and Lovelock as a model that illustrates how life can influence a planet's climate. These models typically involve modeling a planetary surface on which black and white daisies can grow thus influencing the local surface albedo and therefore also the temperature distribution. Since then, variations of daisyworld have been applied to study problems ranging from ecological systems to global climate. Much of the interest in daisyworld models is due to the fact that they enable one to study self-regulating systems. These models are nonlinear, and as such they exhibit sensitive dependence on initial conditions, and depending on the specifics of the model they can also exhibit feedback loops, oscillations, and chaotic behavior. Many daisyworld models are thermodynamic in nature in that they rely on heat flux and temperature gradients. However, what is not well-known is whether, or even why, a daisyworld model might settle into a maximum entropy production (MEP) state. With the aim to better understand these systems, this paper will discuss what is known about the role of MEP in daisyworld models.
Maximum stellar iron core mass
F W Giacobbe
2003-03-01
An analytical method of estimating the mass of a stellar iron core, just prior to core collapse, is described in this paper. The method employed depends, in part, upon an estimate of the true relativistic mass increase experienced by electrons within a highly compressed iron core, just prior to core collapse, and is signiﬁcantly different from a more typical Chandrasekhar mass limit approach. This technique produced a maximum stellar iron core mass value of 2.69 × 1030 kg (1.35 solar masses). This mass value is very near to the typical mass values found for neutron stars in a recent survey of actual neutron star masses. Although slightly lower and higher neutron star masses may also be found, lower mass neutron stars are believed to be formed as a result of enhanced iron core compression due to the weight of non-ferrous matter overlying the iron cores within large stars. And, higher mass neutron stars are likely to be formed as a result of fallback or accretion of additional matter after an initial collapse event involving an iron core having a mass no greater than 2.69 × 1030 kg.
Maximum Matchings via Glauber Dynamics
Jindal, Anant; Pal, Manjish
2011-01-01
In this paper we study the classic problem of computing a maximum cardinality matching in general graphs $G = (V, E)$. The best known algorithm for this problem till date runs in $O(m \\sqrt{n})$ time due to Micali and Vazirani \\cite{MV80}. Even for general bipartite graphs this is the best known running time (the algorithm of Karp and Hopcroft \\cite{HK73} also achieves this bound). For regular bipartite graphs one can achieve an $O(m)$ time algorithm which, following a series of papers, has been recently improved to $O(n \\log n)$ by Goel, Kapralov and Khanna (STOC 2010) \\cite{GKK10}. In this paper we present a randomized algorithm based on the Markov Chain Monte Carlo paradigm which runs in $O(m \\log^2 n)$ time, thereby obtaining a significant improvement over \\cite{MV80}. We use a Markov chain similar to the \\emph{hard-core model} for Glauber Dynamics with \\emph{fugacity} parameter $\\lambda$, which is used to sample independent sets in a graph from the Gibbs Distribution \\cite{V99}, to design a faster algori...
Aerodynamic Modelling and Optimization of Axial Fans
Sørensen, Dan Nørtoft
A numerically efficient mathematical model for the aerodynamics oflow speed axial fans of the arbitrary vortex flow type has been developed.The model is based on a blade-element principle, whereby therotor is divided into a number of annular streamtubes.For each of these streamtubes relations...... for velocity, pressure andradial position are derived from the conservationlaws for mass, tangential momentum and energy.The resulting system of equations is non-linear and, dueto mass conservation and pressure equilibrium far downstream of the rotor,strongly coupled.The equations are solved using the Newton...... distributionsof pitch angle and chord length have been chosen as independent variablesin the optimizations.Besides restricting the geometry of the rotor,constraints have been added to ensure a required pressure rise as well asnon-stalled flow conditions.Optimizations have been performed tomaximize the mean value...
The Axial Part Phrase in Japanese
Kaori Takamine
2007-01-01
Full Text Available In this paper, I investigate the categorial status of spatial terms in locative/directional expressions in Japanese. I will show that a certain class of spatial terms have a distinct categorial status from both regular postpositions and nouns. On one hand, syntactic diagnostics such as doubling, coordination by to, and co-occurrence with demonstratives indicate that these spatial terms belong to a nominal category rather than to a postpositional category. On the other hand, the fact that these spatial terms are modified by range modifiers indicates that they are more similar to regular postpositions than to nouns. On the basis of these diagnostics, I will argue that spatial terms in Japanese need to be assigned a new category Axial Part Phrase which is proposed by Svenonius 2006.
Aerodynamics of advanced axial-flow turbomachinery
Serovy, G. K.; Kavanagh, P.; Kiishi, T. H.
1980-01-01
A multi-task research program on aerodynamic problems in advanced axial-flow turbomachine configurations was carried out at Iowa State University. The elements of this program were intended to contribute directly to the improvement of compressor, fan, and turbine design methods. Experimental efforts in intra-passage flow pattern measurements, unsteady blade row interaction, and control of secondary flow are included, along with computational work on inviscid-viscous interaction blade passage flow techniques. This final report summarizes the results of this program and indicates directions which might be taken in following up these results in future work. In a separate task a study was made of existing turbomachinery research programs and facilities in universities located in the United States. Some potentially significant research topics are discussed which might be successfully attacked in the university atmosphere.
Casimir Energy in the Axial Gauge
Esposito, G; Kirsten, K; Esposito, Giampiero; Kamenshchik, Alexander Yu.; Kirsten, Klaus
2000-01-01
The zero-point energy of a conducting spherical shell is studied by imposing the axial gauge via path-integral methods, with boundary conditions on the electromagnetic potential and ghost fields. The coupled modes are then found to be the temporal and longitudinal modes for the Maxwell field. The resulting system can be decoupled by studying a fourth-order differential equation with boundary conditions on longitudinal modes and their second derivatives. The exact solution of such equation is found by using a Green-function method, and is obtained from Bessel functions and definite integrals involving Bessel functions. Complete agreement with a previous path-integral analysis in the Lorenz gauge, and with Boyer's value, is proved in detail.
2011-01-10
...: Establishing Maximum Allowable Operating Pressure or Maximum Operating Pressure Using Record Evidence, and... facilities of their responsibilities, under Federal integrity management (IM) regulations, to perform... system, especially when calculating Maximum Allowable Operating Pressure (MAOP) or Maximum Operating...
A maximum in the strength of nanocrystalline copper
Schiøtz, Jakob; Jacobsen, Karsten Wedel
2003-01-01
We used molecular dynamics simulations with system sizes up to 100 million atoms to simulate plastic deformation of nanocrystalline copper. By varying the grain size between 5 and 50 nanometers, we show that the flow stress and thus the strength exhibit a maximum at a grain size of 10 to 15...... nanometers. This maximum is because of a shift in the microscopic deformation mechanism from dislocation-mediated plasticity in the coarse-grained material to grain boundary sliding in the nanocrystalline region. The simulations allow us to observe the mechanisms behind the grain-size dependence...
Axial focusing of energy from a hypervelocity impact on earth
Boslough, M.B.; Chael, E.P.; Trucano, T.G.; Crawford, D.A.
1994-12-01
We have performed computational simulations to determine how energy from a large hypervelocity impact on the Earth`s surface would couple to its interior. Because of the first-order axial symmetry of both the impact energy source and the stress-wave velocity structure of the Earth, a disproportionate amount of energy is dissipated along the axis defined by the impact point and its antipode (point opposite the impact). For a symmetric and homogeneous Earth model, all the impact energy that is radiated as seismic waves into the Earth at a given takeoff angle (ray parameter), independent of azimuthal direction, is refocused (minus attenuation) on the axis of symmetry, regardless of the number of reflections and refractions it has experienced. Material on or near the axis of symmetry experiences more strain cycles with much greater amplitude than elsewhere, and therefore experiences more irreversible heating. The focusing is most intense in the upper mantle, within the asthenosphere, where seismic energy is most effectively converted to heat. For a sufficiently energetic impact, this mechanism might generate enough local heating to create an isostatic instability leading to uplift, possibly resulting in rifting, volcanism, or other rearrangement of the interior dynamics of the planet. These simulations demonstrate how hypervelocity impact energy can be transported to the Earth`s interior, supporting the possibility of a causal link between large impacts on Earth and major internally-driven geophysical processes.
Internal resonance of axially moving laminated circular cylindrical shells
Wang, Yan Qing; Liang, Li; Guo, Xing Hui
2013-11-01
The nonlinear vibrations of a thin, elastic, laminated composite circular cylindrical shell, moving in axial direction and having an internal resonance, are investigated in this study. Nonlinearities due to large-amplitude shell motion are considered by using Donnell's nonlinear shallow-shell theory, with consideration of the effect of viscous structure damping. Differently from conventional Donnell's nonlinear shallow-shell equations, an improved nonlinear model without employing Airy stress function is developed to study the nonlinear dynamics of thin shells. The system is discretized by Galerkin's method while a model involving four degrees of freedom, allowing for the traveling wave response of the shell, is adopted. The method of harmonic balance is applied to study the nonlinear dynamic responses of the multi-degrees-of-freedom system. When the structure is excited close to a resonant frequency, very intricate frequency-response curves are obtained, which show strong modal interactions and one-to-one-to-one-to-one internal resonance phenomenon. The effects of different parameters on the complex dynamic response are investigated in this study. The stability of steady-state solutions is also analyzed in detail.
STUDY OF AXIAL VELOCITY IN GAS CYCLONES BY 2D-PIV, 3D-PIY, AND SIMULATION
Zhengliang Liu; Jinyu Jiao; Ying Zheng
2006-01-01
The axial velocity distribution in a gas cyclone has been examined with two-dimensional particle image velocimetry (2D-PIV) and three-dimensional particle image velocimetry (3D-PIV) experiments in this study. Due to the limitation of 2D-PIV configuration, the contamination generated by the strong tangential velocity in the cyclone can be registered in the axial velocity detected by 2D-PIV. Efficient methods are proposed in this work to remove this contamination. The contamination-removed 2D-PIV data agree well with 3D-PIV results. The distributions of the axial velocity are also computed by the Reynolds stress model (RSM) and verified using the PIV experimental results. Reasonable agreements are obtained.
The Sherpa Maximum Likelihood Estimator
Nguyen, D.; Doe, S.; Evans, I.; Hain, R.; Primini, F.
2011-07-01
A primary goal for the second release of the Chandra Source Catalog (CSC) is to include X-ray sources with as few as 5 photon counts detected in stacked observations of the same field, while maintaining acceptable detection efficiency and false source rates. Aggressive source detection methods will result in detection of many false positive source candidates. Candidate detections will then be sent to a new tool, the Maximum Likelihood Estimator (MLE), to evaluate the likelihood that a detection is a real source. MLE uses the Sherpa modeling and fitting engine to fit a model of a background and source to multiple overlapping candidate source regions. A background model is calculated by simultaneously fitting the observed photon flux in multiple background regions. This model is used to determine the quality of the fit statistic for a background-only hypothesis in the potential source region. The statistic for a background-plus-source hypothesis is calculated by adding a Gaussian source model convolved with the appropriate Chandra point spread function (PSF) and simultaneously fitting the observed photon flux in each observation in the stack. Since a candidate source may be located anywhere in the field of view of each stacked observation, a different PSF must be used for each observation because of the strong spatial dependence of the Chandra PSF. The likelihood of a valid source being detected is a function of the two statistics (for background alone, and for background-plus-source). The MLE tool is an extensible Python module with potential for use by the general Chandra user.
Vestige: Maximum likelihood phylogenetic footprinting
Maxwell Peter
2005-05-01
Full Text Available Abstract Background Phylogenetic footprinting is the identification of functional regions of DNA by their evolutionary conservation. This is achieved by comparing orthologous regions from multiple species and identifying the DNA regions that have diverged less than neutral DNA. Vestige is a phylogenetic footprinting package built on the PyEvolve toolkit that uses probabilistic molecular evolutionary modelling to represent aspects of sequence evolution, including the conventional divergence measure employed by other footprinting approaches. In addition to measuring the divergence, Vestige allows the expansion of the definition of a phylogenetic footprint to include variation in the distribution of any molecular evolutionary processes. This is achieved by displaying the distribution of model parameters that represent partitions of molecular evolutionary substitutions. Examination of the spatial incidence of these effects across regions of the genome can identify DNA segments that differ in the nature of the evolutionary process. Results Vestige was applied to a reference dataset of the SCL locus from four species and provided clear identification of the known conserved regions in this dataset. To demonstrate the flexibility to use diverse models of molecular evolution and dissect the nature of the evolutionary process Vestige was used to footprint the Ka/Ks ratio in primate BRCA1 with a codon model of evolution. Two regions of putative adaptive evolution were identified illustrating the ability of Vestige to represent the spatial distribution of distinct molecular evolutionary processes. Conclusion Vestige provides a flexible, open platform for phylogenetic footprinting. Underpinned by the PyEvolve toolkit, Vestige provides a framework for visualising the signatures of evolutionary processes across the genome of numerous organisms simultaneously. By exploiting the maximum-likelihood statistical framework, the complex interplay between mutational
Concentration influences on recovery in a high gradient magnetic separation axial filter
Murariu, V.; Rezlescu, N.; Rotariu, O.; Badescu, V. [Inst. of Technical Physics, Iasi (Romania)
1998-05-01
The buildup differential equations for the case of a single wire in high gradient magnetic filtration (HGMF)-axial configuration taking into account the suspension concentration are solved. A new equation for the deposit contour surface at different moments and for different suspension concentrations are obtained. The existence of a particulate suspension concentration, for which the radial extension velocity of deposit is maximum, is evidenced. The recovery for an ordered ferromagnetic matrix is calculated. The influence of the solid particle concentration from suspension on the filtration efficiency is presented.
Xiang Xu
2013-09-01
Full Text Available This paper presents a novel method to nonlinearly investigate the dynamics of the coupled axial and torsional vibrations in the circular cross section beam of the steam turbine generator using the FFT analysis. Firstly, the coupled axial and torsional vibrations of a beam are proved by equivalent law of shearing stress and different boundary conditions. Then, a nonlinear mathematical model of the coupled axial and torsional vibrations is established by the Galerkin method. Lastly, the fast Fourier transform (FFT is employed to investigate the coupled effect of the beam vibration. A practical calculation example is calculated numerically and the coupled mechanism of the beam’s axial and torsional vibrations is analyzed in detail. The analysis results show that the frequencies of the coupled response would be existed in some special orders and the coupled response frequencies are smaller than the single vibration. Since for the first time the coupled mechanism of the beam’s axial and torsional vibrations is theoretically analyzed, the findings in this work may provide directive reference for practical engineering problems in design of steam turbine generators.
Arunachalam Sangeetha
2012-01-01
Full Text Available Context: To understand the effect of masticatory and parafunctional forces on the integrity of the prosthesis and the underlying cement layer. Aims: The purpose of this study was to evaluate the stress pattern in the cement layer and the fixed prosthesis, on subjecting a three-dimensional finite element model to simulated occlusal loading. Materials and Methods: Three-dimensional finite element model was simulated to replace missing mandibular first molar with second premolar and second molar as abutments. The model was subjected to a range of occlusal loads (20, 30, 40 MPa in two different directions - vertical and 30° to the vertical. The cements (zinc phosphate, polycarboxylate, glass ionomer, and composite were modeled with two cement thicknesses - 25 and 100 μm. Stresses were determined in certain reference points in fixed prosthesis and the cement layer. Statistical Analysis Used: The stress values are mathematic calculations without variance; hence, statistical analysis is not routinely required. Results: Stress levels were calculated according to Von Mises criteria for each node. Maximum stresses were recorded at the occlusal surface, axio-gingival corners, followed by axial wall. The stresses were greater with lateral load and with 100-μm cement thickness. Results revealed higher stresses for zinc phosphate cement, followed by composites. Conclusions: The thinner cement interfaces favor the success of the prosthesis. The stresses in the prosthesis suggest rounding of axio-gingival corners and a well-established finish line as important factors in maintaining the integrity of the prosthesis.
Through flow analysis within axial flow turbomachinery blade rows
Girigoswami, H.
1986-09-01
Using Katsanis' Through Flow Code, inviscid flow through an axial flow compressor rotor blade as well as flow through inlet guide vanes are analyzed and the computed parameters such as meridional velocity distribution, axial velocity distribution along radial lines, and velocity distribution over blade surfaces are presented.
Improved axial position detection in optical tweezers measurements
Dreyer, Jakob Kisbye; Berg-Sørensen, Kirstine; Oddershede, Lene
2004-01-01
We investigate the axial position detection of a trapped microsphere in an optical trap by using a quadrant photodiode. By replacing the photodiode with a CCD camera, we obtain detailed information on the light scattered by the microsphere. The correlation of the interference pattern with the axial...
Testing of Axially Loaded Bucket Foundation with Applied Overburden Pressure
Vaitkunaite, Evelina; Ibsen, Lars Bo; Nielsen, Benjaminn Nordahl
This report analyses laboratory testing data performed with a bucket foundation model subjected to axial loading. The examinations were conducted at the Geotechnical laboratory of Aalborg University. The report aims at showing and discussing the results of the static and cyclic axial loading tests...
Test Setup for Axially Loaded Piles in Sand
Thomassen, Kristina
The test setup for testing axially static and cyclic loaded piles in sand is described in the following. The purpose for the tests is to examine the tensile capacity of axially loaded piles in dense fully saturated sand. The pile dimensions are chosen to resemble full scale dimension of piles used...... in offshore pile foundations today....
An Unbroken Axial-Vector Current Conservation Law
Sharafiddinov, Rasulkhozha S.
2016-04-01
The mass, energy and momentum of the neutrino of a true flavor have an axial-vector nature. As a consequence, the left-handed truly neutral neutrino in an axial-vector field of emission can be converted into a right-handed one and vice versa. This predicts the unidenticality of masses, energies and momenta of neutrinos of the different components. Recognizing such a difference in masses, energies, momenta and accepting that the left-handed axial-vector neutrino and the right-handed antineutrino of true neutrality refer to long-lived C-odd leptons, and the right-handed truly neutral neutrino and the left-handed axial-vector antineutrino are of short-lived fermions of C-oddity, we would write a new CP-even Dirac equation taking into account the flavor symmetrical axial-vector mass, energy and momentum matrices. Their presence explains the spontaneous mirror symmetry violation, confirming that an axial-vector current conservation law has never violated. They reflect the availability of a mirror Minkowski space in which a neutrino is characterized by left as well as by right space-time coordinates. Therefore, it is not surprising that whatever the main purposes experiments about a quasielastic axial-vector mass say in favor of an axial-vector mirror Minkowski space-time.
A new approach to radial and axial gauges
Weigert, Heribert; Heinz, Ulrich
1992-03-01
We develop a new path integral formulation of QCD in radial and axial gauges. This formalism yields free propagators which are free of gauge poles. We find that radial gauges are ghost free. In axial gauges ghosts cannot generally be excluded from the formalism due to the need to fix the residual gauge freedom.
Development of an axial suspended AMB experimental bench for load and disturbance tests
R. Gouws
2015-06-01
Full Text Available This paper provides the development of an axial suspended active magnetic bearing (AMB experimental bench for load and disturbance tests. This test bench must be capable of levitating a 2 kg steel disc at a stable working distance of 3 mm and a maximum attraction distance of 6 mm. The suspension is accomplished by two electromagnets producing upward and downward attraction forces to support the steel disc. An inductive sensor measures the position of the steel disc and relays this to a PC based controller board (dSPACE® controller. The control system uses this information to regulate the electromagnetic force on the steel disc. The intent is to construct this system using relatively low-cost, low-precision components, and still be able to stably levitate the 2 kg steel disc with high precision. The dSPACE® software (ControlDesk® was used for data acquisition. In this paper, an overview of the system design is presented, followed by the axial AMB model design, inductive sensor design, actuating unit design and controller development and implementation. The paper concludes with results obtained from the dSPACE® controller and evaluation of the axial suspended AMB experimental bench with load and disturbance tests.
Volar morphology of the distal radius in axial planes: a quantitative analysis.
Oura, Keiichiro; Oka, Kunihiro; Kawanishi, Yohei; Sugamoto, Kazuomi; Yoshikawa, Hideki; Murase, Tsuyoshi
2015-04-01
To investigate the cause of rupture of the flexor pollicis longus (FPL) after volar plate fixation of distal radius fractures, previous studies have examined the shape of the distal radius in the sagittal plane or in the lateral view. However, there are no reports on the anatomical shape of the volar surface concavity of the distal radius in the axial plane. We hypothesized that this concavity might contribute to the mismatch between the plate and the surface of the radius. To test this hypothesis, we constructed three-dimensional models of the radius and FPL based on computed tomography scans of 70 normal forearms. We analyzed axial cross-sectional views with 2 mm intervals. In all cases, the volar surface of the distal radius was concave in the axial plane. The concavity depth was maximum at 6 mm proximal to the palmar edge of the lunate fossa and progressively decreased toward the proximal radius. FPL was closest to the radius at 2 mm proximal to the palmar edge of the lunate fossa. The volar surface of the distal radius was externally rotated from proximal to distal. These results may help to develop new implants which fit better to the radius and decrease tendon irritation.
Remaining useful life prediction based on the Wiener process for an aviation axial piston pump
Wang Xingjian; Lin Siru; Wang Shaoping; He Zhaomin; Zhang Chao
2016-01-01
An aviation hydraulic axial piston pump’s degradation from comprehensive wear is a typical gradual failure model. Accurate wear prediction is difficult as random and uncertain char-acteristics must be factored into the estimation. The internal wear status of the axial piston pump is characterized by the return oil flow based on fault mechanism analysis of the main frictional pairs in the pump. The performance degradation model is described by the Wiener process to predict the remaining useful life (RUL) of the pump. Maximum likelihood estimation (MLE) is performed by utilizing the expectation maximization (EM) algorithm to estimate the initial parameters of the Wiener process while recursive estimation is conducted utilizing the Kalman filter method to estimate the drift coefficient of the Wiener process. The RUL of the pump is then calculated accord-ing to the performance degradation model based on the Wiener process. Experimental results indi-cate that the return oil flow is a suitable characteristic for reflecting the internal wear status of the axial piston pump, and thus the Wiener process-based method may effectively predicate the RUL of the pump.
Axial vibration analysis of nanocones based on nonlocal elasticity theory
Shu-Qi Guo; Shao-Pu Yang
2012-01-01
Carbon nanocones have quite fascinating electronic and structural properties,whose axial vibration is seldom investigated in previous studies.In this paper,based on a nonlocal elasticity theory,a nonuniform rod model is applied to investigate the small-scale effect and the nonuniform effect on axial vibration of nanocones.Using the modified Wentzel-Brillouin-Kramers (WBK) method,an asymptotic solution is obtained for the axial vibration of general nonuniform nanorods.Then,using similar procedure,the axial vibration of nanocones is analyzed for nonuniform parameters,mode number and nonlocal parameters.Explicit expressions are derived for mode frequencies of clamped-clamped and clamped-free boundary conditions.It is found that axial vibration frequencies are highly overestimated by the classical rod model because of ignorance of the effect of small length scale.
On Stationary Axially Symmetric Solutions in Brans-Dicke Theory
Kirezli, Pınar
2015-01-01
Stationary axially symmetric Brans-Dicke-Maxwell solutions are re-examined in the framework of the Brans-Dicke theory. We see that, employing a particular parametrization of the standard axially symmetric metric simplifies the procedure of obtaining the Ernst equations for axially symmetric electro-vacuum space-times for this theory. This analysis also permit us to construct a two parameter extension in both Jordan and Einstein frames of an old solution generating technique frequently used to construct axially symmetric solutions for Brans-Dicke theory from a seed solution of General Relativity. As applications of this technique, several known and new solutions are constructed including a general axially symmetric BD-Maxwell solution of Plebanski-Demianski with vanishing cosmological constant, i.e. the Kinnersley solution and general magnetized Kerr-Newman type solutions. Some physical properties and circular motion of test particles for a particular subclass of Kinnersley solution, i.e. Kerr-Newman-NUT type ...
Verkaik, A. C.; Beulen, B. W. A. M. M.; Bogaerds, A. C. B.; Rutten, M. C. M.; van de Vosse, F. N.
2009-02-01
To monitor biomechanical parameters related to cardiovascular disease, it is necessary to perform correct volume flow estimations of blood flow in arteries based on local blood velocity measurements. In clinical practice, estimates of flow are currently made using a straight-tube assumption, which may lead to inaccuracies since most arteries are curved. Therefore, this study will focus on the effect of curvature on the axial velocity profile for flow in a curved tube in order to find a new volume flow estimation method. The study is restricted to steady flow, enabling the use of analytical methods. First, analytical approximation methods for steady flow in curved tubes at low Dean numbers (Dn) and low curvature ratios (δ) are investigated. From the results a novel volume flow estimation method, the cos θ-method, is derived. Simulations for curved tube flow in the physiological range (1≤Dn≤1000 and 0.01≤δ≤0.16) are performed with a computational fluid dynamics (CFD) model. The asymmetric axial velocity profiles of the analytical approximation methods are compared with the velocity profiles of the CFD model. Next, the cos θ-method is validated and compared with the currently used Poiseuille method by using the CFD results as input. Comparison of the axial velocity profiles of the CFD model with the approximations derived by Topakoglu [J. Math. Mech. 16, 1321 (1967)] and Siggers and Waters [Phys. Fluids 17, 077102 (2005)] shows that the derived velocity profiles agree very well for Dn≤50 and are fair for 50100), no analytical approximation method exists. In the position of the maximum axial velocity, a shift toward the inside of the curve is observed for low Dean numbers, while for high Dean numbers, the position of the maximum velocity is located at the outer curve. When the position of the maximum velocity of the axial velocity profile is given as a function of the Reynolds number, a "zero-shift point" is found at Re=21.3. At this point the shift in
Axial Vibration Confinement in Nonhomogenous Rods
S. Choura
2005-01-01
Full Text Available A design methodology for the vibration confinement of axial vibrations in nonhomogenous rods is proposed. This is achieved by a proper selection of a set of spatially dependent functions characterizing the rod material and geometric properties. Conditions for selecting such properties are established by constructing positive Lyapunov functions whose derivative with respect to the space variable is negative. It is shown that varying the shape of the rod alone is sufficient to confine the vibratory motion. In such a case, the vibration confinement requires that the eigenfunctions be exponentially decaying functions of space, where the notion of spatial domain stability is introduced as a concept dual to that of the time domain stability. It is also shown that vibration confinement can be produced if the rod density and/or stiffness are varied with respect to the space variable while the cross-section area is kept constant. Several case studies, supporting the developed conditions imposed on the spatially dependent functions for vibration confinement in vibrating rods, are discussed. Because variation in the geometric and material properties might decrease the critical buckling loads, we also discuss the buckling problem.
Computerized axial tomography in clinical pediatrics.
McCullough, D C; Kufta, C; Axelbaum, S P; Schellinger, D
1977-02-01
Computerized axial tomography (CAT), a noninvasive radiologie method, provides a new dimension in screening and diagnosis of intracranial pathology. Evaluation of 725 scans in infants and children demonstrates that CAT may be performed with negligible risk, although sedation and restraint are essential to the successful performance of studies in children under 6 years of age. CAT is the preferred initial diagnostic method in suspected hydrocephalls and is accurate in the detection and precise localization of brain tumors. The management of hydrocephalus and brain tumors has been significantly altered by the availability of CAT. Few invasive neuroradiologic procedures are required and pneumography is especially curtailed. Serial scanning is the best available method of monitoring ventricular alterations in hydrocephalus, tumor size during radiotherapy or chemotherapy, and postoperative recurrence of benign neoplasms. Complex intracranial anomalies are detectable with computerized tomography, but complete definition of pathology often requires angiography and air studies. Limited clinical experience in detecting neonatal intraventricular hemorrhage suggests that CAT will be a valuable tool for futlre investigations of that problem.
Multimode interaction in axially excited cylindrical shells
Silva F. M. A.
2014-01-01
Full Text Available Cylindrical shells exhibit a dense frequency spectrum, especially near the lowest frequency range. In addition, due to the circumferential symmetry, frequencies occur in pairs. So, in the vicinity of the lowest natural frequencies, several equal or nearly equal frequencies may occur, leading to a complex dynamic behavior. So, the aim of the present work is to investigate the dynamic behavior and stability of cylindrical shells under axial forcing with multiple equal or nearly equal natural frequencies. The shell is modelled using the Donnell nonlinear shallow shell theory and the discretized equations of motion are obtained by applying the Galerkin method. For this, a modal solution that takes into account the modal interaction among the relevant modes and the influence of their companion modes (modes with rotational symmetry, which satisfies the boundary and continuity conditions of the shell, is derived. Special attention is given to the 1:1:1:1 internal resonance (four interacting modes. Solving numerically the governing equations of motion and using several tools of nonlinear dynamics, a detailed parametric analysis is conducted to clarify the influence of the internal resonances on the bifurcations, stability boundaries, nonlinear vibration modes and basins of attraction of the structure.
Axially Symmetric Post-Newtonian Stellar Systems
Camilo Akímushkin
2010-06-01
Full Text Available We introduce a method to obtain self-consistent, axially symmetric disklike stellar models in the first post-Newtonian (1PN approximation. By using in the field equations of the 1PN approximation a distribution function (DF corresponding to a Newtonian model, two fundamental equations determining the 1PN corrections are obtained. The rotation curves of the corrected models differs from the classical ones and the corrections are clearly appreciable with values of the mass and radius of a typical galaxy. On the other hand, the relativistic mass correction can be ignored for all models. Resumen. Presentamos un método para obtener modelos estelares discoidales, axialmente simétricos, auto-consistentes en la primera aproximación post-Newtoniana (1PN. Usando en las ecuaciones de campo de la aproximación 1PN una función de distribución conocida (DF que corresponde a un modelo Newtoniano, se obtienen dos ecuaciones fundamentales para determinar las correcciones 1PN. Las curvas de rotación de los modelos corregidos difieren de las clásicas y las correcciones son claramente apreciables con los valores de la masa y el radio de una galaxia típica. Por otro lado, la corrección relativista de la masa se puede ignorar para todos los modelos.
New treatment targets for axial spondyloarthritis.
Sieper, Joachim
2016-12-01
Axial spondyloarthritis (axSpA) patients can be divided into those with structural damage in the SI joint visible on X-rays, termed radiographic axSpA or AS, and those in an earlier phase of the disease, without structural damage in the SI joint, termed non-radiographic axSpA. TNF-blockers have been shown to be highly effective in the treatment of active axSpA. Interestingly, conventional DMARDs and also non-TNF-blocker biologics targeting IL-1, IL-6 and T cells (abatacept) are not effective. Recent interest has focused on the cytokines IL-23 and IL-17 as potential treatment targets in axSpA. An open-label trial with ustekinumab showed a good efficacy in AS patients. Two placebo-controlled phase 3 trials with a mAb blocking IL-17, secukinumab, showed a good reduction in disease activity, similar to that shown for TNF blockers. Probably triggered by inflammation, new bone formation is another hallmark in AS and a potentially important treatment target. However, a previously reported inhibitory effect of NSAID treatment could not be confirmed in a recent NSAID trial.
Vertebrate Axial Patterning: From Egg to Asymmetry.
Houston, Douglas W
2017-01-01
The emergence of the bilateral embryonic body axis from a symmetrical egg has been a long-standing question in developmental biology. Historical and modern experiments point to an initial symmetry-breaking event leading to localized Wnt and Nodal growth factor signaling and subsequent induction and formation of a self-regulating dorsal "organizer." This organizer forms at the site of notochord cell internalization and expresses primarily Bone Morphogenetic Protein (BMP) growth factor antagonists that establish a spatiotemporal gradient of BMP signaling across the embryo, directing initial cell differentiation and morphogenesis. Although the basics of this model have been known for some time, many of the molecular and cellular details have only recently been elucidated and the extent that these events remain conserved throughout vertebrate evolution remains unclear. This chapter summarizes historical perspectives as well as recent molecular and genetic advances regarding: (1) the mechanisms that regulate symmetry-breaking in the vertebrate egg and early embryo, (2) the pathways that are activated by these events, in particular the Wnt pathway, and the role of these pathways in the formation and function of the organizer, and (3) how these pathways also mediate anteroposterior patterning and axial morphogenesis. Emphasis is placed on comparative aspects of the egg-to-embryo transition across vertebrates and their evolution. The future prospects for work regarding self-organization and gene regulatory networks in the context of early axis formation are also discussed.
Nitinol stent design - understanding axial buckling.
McGrath, D J; O'Brien, B; Bruzzi, M; McHugh, P E
2014-12-01
Nitinol׳s superelastic properties permit self-expanding stents to be crimped without plastic deformation, but its nonlinear properties can contribute towards stent buckling. This study investigates the axial buckling of a prototype tracheobronchial nitinol stent design during crimping, with the objective of eliminating buckling from the design. To capture the stent buckling mechanism a computational model of a radial force test is simulated, where small geometric defects are introduced to remove symmetry and allow buckling to occur. With the buckling mechanism ascertained, a sensitivity study is carried out to examine the effect that the transitional plateau region of the nitinol loading curve has on stent stability. Results of this analysis are then used to redesign the stent and remove buckling. It is found that the transitional plateau region can have a significant effect on the stability of a stent during crimping, and by reducing the amount of transitional material within the stent hinges during loading the stability of a nitinol stent can be increased.
Corrosion Fatigue of High-Strength Titanium Alloys Under Different Stress Gradients
Baragetti, Sergio; Villa, Francesco
2015-05-01
Ti-6Al-4V is the most widely used high strength-to-mass ratio titanium alloy for advanced engineering components. Its adoption in the aerospace, maritime, automotive, and biomedical sectors is encouraged when highly stressed components with severe fatigue loading are designed. The extents of its applications expose the alloy to several aggressive environments, which can compromise its brilliant mechanical characteristics, leading to potentially catastrophic failures. Ti-6Al-4V stress-corrosion cracking and corrosion-fatigue sensitivity has been known since the material testing for pressurized tanks for Apollo missions, although detailed investigations on the effects of harsh environment in terms of maximum stress reduction have been not carried out until recent times. In the current work, recent experimental results from the authors' research group are presented, quantifying the effects of aggressive environments on Ti-6Al-4V under fatigue loading in terms of maximum stress reduction. R = 0.1 axial fatigue results in laboratory air, 3.5 wt.% NaCl solution, and CH3OH methanol solution at different concentrations are obtained for mild notched specimens ( K t = 1.18) at 2e5 cycles. R = 0.1 tests are also conducted in laboratory air, inert environment, 3.5 wt.% NaCl solution for smooth, mild and sharp notched specimens, with K t ranging from 1 to 18.65, highlighting the environmental effects for the different load conditions induced by the specimen geometry.
A Constitutive Model for Uni-axial Compaction of Non-adhesive Corn Stalk Powder
Zhao Dong; Sun Yanling
2004-01-01
In order to study mechanical behaviors of corn stalk powder during the compaction, the yield criterion for corn stalk powder is proposed with a plasticity theory. From the stress-strain curves of uni-axial compaction test for corn stalk powder, the constitutive model, in which the equations are modified by experiments on corn stalk powder, is adopted to describe plastic behaviors of powder, and is discussed based on the incremental theory and deformation theory. The numerical results agree well with the experimental ones.
Modeling of FRP-jacketed RC columns subject to combined axial and lateral loads
Lee, Chung-Sheng
2006-01-01
To successfully use the fiber-reinforced-polymer (FRP) overlay technique for the seismic retrofit and the blast- hardening of RC columns, the mechanical behavior of the FRP-confined concrete needs to be understood and its response needs to be accurately predicted. Although a number of studies have been conducted to-date, it is still not clear how the main parameters affect the axial stress- strain response of a FRP-confined concrete cylinder. In particular, while it is understood that FRP jac...
Structural and optical properties of axial silicon-germanium nanowire heterojunctions
Wang, X.; Tsybeskov, L., E-mail: tsybesko@njit.edu [ECE Department, New Jersey Institute of Technology, Newark, New Jersey 07102 (United States); Kamins, T. I. [Department of Electrical Engineering, Stanford University, Stanford, California 94305 (United States); Wu, X.; Lockwood, D. J. [National Research Council, Ottawa, Ontario K1A 0R6 (Canada)
2015-12-21
Detailed studies of the structural and optical properties of axial silicon-germanium nanowire heterojunctions show that despite the 4.2% lattice mismatch between Si and Ge they can be grown without a significant density of structural defects. The lattice mismatch induced strain is partially relieved due to spontaneous SiGe intermixing at the heterointerface during growth and lateral expansion of the Ge segment of the nanowire. The mismatch in Ge and Si coefficients of thermal expansion and low thermal conductivity of Si/Ge nanowire heterojunctions are proposed to be responsible for the thermally induced stress detected under intense laser radiation in photoluminescence and Raman scattering measurements.
Lim, Tau Meng; Cheng, Shanbao; Chua, Leok Poh
2009-07-01
Axial flow blood pumps are generally smaller as compared to centrifugal pumps. This is very beneficial because they can provide better anatomical fit in the chest cavity, as well as lower the risk of infection. This article discusses the design, levitated responses, and parameter estimation of the dynamic characteristics of a compact hybrid magnetic bearing (HMB) system for axial flow blood pump applications. The rotor/impeller of the pump is driven by a three-phase permanent magnet brushless and sensorless motor. It is levitated by two HMBs at both ends in five degree of freedom with proportional-integral-derivative controllers, among which four radial directions are actively controlled and one axial direction is passively controlled. The frequency domain parameter estimation technique with statistical analysis is adopted to validate the stiffness and damping coefficients of the HMB system. A specially designed test rig facilitated the estimation of the bearing's coefficients in air-in both the radial and axial directions. Experimental estimation showed that the dynamic characteristics of the HMB system are dominated by the frequency-dependent stiffness coefficients. By injecting a multifrequency excitation force signal onto the rotor through the HMBs, it is noticed in the experimental results the maximum displacement linear operating range is 20% of the static eccentricity with respect to the rotor and stator gap clearance. The actuator gain was also successfully calibrated and may potentially extend the parameter estimation technique developed in the study of identification and monitoring of the pump's dynamic properties under normal operating conditions with fluid.
Internal stress field at Mount Vesuvius: A model for background seismicity at a central volcano
de Natale, Giuseppe; Petrazzuoli, Stefano M.; Troise, Claudia; Pingue, Folco; Capuano, Paolo
2000-07-01
We propose a model to explain the background seismicity occurring at Somma-Vesuvius in its present, mostly quiescent period. A finite element procedure has been used to simulate the stress field due to gravitational body forces in an axisymmetric volcano characterized by a central high-rigidity anomaly. Results emphasize the important effect of axial high-rigidity, which concentrates at its borders stresses resulting from the gravitational load of the volcanic edifice, as well as external (regional) stresses. The joint effect of the gravitational loading and of the presence of the anomaly produces stresses very close to or above the critical rupture threshold. The observed spatial concentrations of seismicity and moment release correlate well with peaks of computed maximum shear stress. Seismicity is then interpreted as due to small stress perturbations concentrated around the high-rigidity core and added to a system already close, to the failure threshold. This model can explain the widely observed occurrence of background seismicity at central volcanoes worldwide.
F. Aguilar Parés
1999-01-01
Full Text Available Durante el movimiento de un material en un transportador de sinfín surge una fuerza en dirección axial que influye en laselección de uno de los cojinetes de apoyo del equipo. En el artículo aparecen algunas soluciones constructivas que tienen encuentan la fuerza axial. Por otro lado se establece la relación entre la fuerza axial y el empuje axial y se precisa de quiendepende el sentido del empuje axial. Por último se propone un modelo matemático que relaciona la fuerza axial con la potenciarequerida por el equipo.Palabras claves: Transportador de sinf in, fuerza axial , empuje axial ._________________________________________________________________________AbstractDuring the movement of material in a screw conveyor surge a force in axial direction that influence in the selection of one ofthe equipment support bearings. Some constructive solutions appear in the article for considering the axial force. In the otherhand it is established the relation between axial force and axial thurst and it is precised whose direction thurst axial depend of.Finally it is proposed a mathematic model that relates the axial force with the power required by the equipment.Key words: Screw conveyor, axial force, axial thurst .
Tunable Clamped–Guided Arch Resonators Using Electrostatically Induced Axial Loads
Alcheikh, Nouha
2017-01-04
We present a simulation and experimental investigation of bi-directional tunable in-plane clamped-guided arch microbeam resonators. Tensile and compressive axial forces are generated from a bi-directional electrostatic actuator, which modulates the microbeam stiffness, and hence changes its natural frequency to lower or higher values from its as-fabricated value. Several devices of various anchor designs and geometries are fabricated. We found that for the fabricated shallow arches, the effect of the curvature of the arch is less important compared to the induced axial stress from the axial load. We have shown that the first mode resonance frequency can be increased up to twice its initial value. Additionally, the third mode resonance frequency can be increased up to 30% of its initial value. These results can be promising as a proof-of-concept for the realization of wide-range tunable microresonators. The experimental results have been compared to finite-element simulations, showing good agreement among them.
Analysis of blade vibration response induced by rotating stall in axial compressor
2012-01-01
An experimental and numerical study was conducted to investigate the forced response of blade vibration induced by rotating stall in a low speed axial compressor.Measurements have been made of the transient stalling process in a low speed axial compressor stage.The CFD study was performed using solution of 3-dimensional Navier-Stokes equations,coupled with structure finite element models for the blades to identify modal shapes and structural deformations simultaneously.Interactions between fluid and structure were managed in a coupled manner,based on the interface information exchange until convergence in each time step.Based on the rotating stall measurement data obtained from a low speed axial compressor,the blade aeroelastic response induced by the rotating stall flow field was analyzed to study the vibration characteristics and the correlation between the phenomena.With this approach,good agreement between the numerical results and the experimental data was observed.The flow phenomena were well captured,and the results indicate that the rotating field stall plays a significant role in the blade vibration and stress affected by the flow excitation.
Turning maneuvers in sharks: Predicting body curvature from axial morphology.
Porter, Marianne E; Roque, Cassandra M; Long, John H
2009-08-01
Given the diversity of vertebral morphologies among fishes, it is tempting to propose causal links between axial morphology and body curvature. We propose that shape and size of the vertebrae, intervertebral joints, and the body will more accurately predict differences in body curvature during swimming rather than a single meristic such as total vertebral number alone. We examined the correlation between morphological features and maximum body curvature seen during routine turns in five species of shark: Triakis semifasciata, Heterodontus francisci, Chiloscyllium plagiosum, Chiloscyllium punctatum, and Hemiscyllium ocellatum. We quantified overall body curvature using three different metrics. From a separate group of size-matched individuals, we measured 16 morphological features from precaudal vertebrae and the body. As predicted, a larger pool of morphological features yielded a more robust prediction of maximal body curvature than vertebral number alone. Stepwise linear regression showed that up to 11 features were significant predictors of the three measures of body curvature, yielding highly significant multiple regressions with r(2) values of 0.523, 0.537, and 0.584. The second moment of area of the centrum was always the best predictor, followed by either centrum length or transverse height. Ranking as the fifth most important variable in three different models, the body's total length, fineness ratio, and width were the most important non-vertebral morphologies. Without considering the effects of muscle activity, these correlations suggest a dominant role for the vertebral column in providing the passive mechanical properties of the body that control, in part, body curvature during swimming. (c) 2009 Wiley-Liss, Inc.
Jelen, Karel; Klouckova, Katerina; Zeman, Josef; Kubovy, Petr; Fanta, Ondrej
2012-01-01
vibration or other type of load. Or conversely before and after relaxation on a bed. Results of this work will be further analyzed, verified and evaluation procedures will be improved. We expect to find dependencies between excitation and resonance frequencies during the transfer via the axial system, the rheological properties of the axial system components and the physical nature of the load of the axial system. They are then going to be applicable for the prevention of injuries of the axial system, physiotherapy practices in the rehabilitation of post-operative conditions, the dosage of training loads of athletes, in determining the effects of job stress regimes and their prevention.
Active axial spondyloarthritis: potential role of certolizumab pegol
Ranatunga S
2014-02-01
Full Text Available Sriya Ranatunga, Anne V Miller Department of Internal Medicine, Southern Illinois University School of Medicine, Springfield, IL, USA Abstract: The axial spondyloarthropathies are a group of chronic inflammatory diseases that predominantly affect the axial joints. This group includes ankylosing spondylitis and nonradiographic axial spondyloarthropathy. While the pathogenesis of axial spondyloarthropathies is not clear, immunologically active tissues primarily include the entheses, ie, the areas where ligaments, tendons, and joint capsules attach to bone and to the annulus fibrosis at the vertebrae. One of the major mediators of the immune response in this group of diseases is tumor necrosis factor-alpha (TNFα. Blockade of TNFα results in reduced vascularity and inflammatory cell infiltration in the synovial tissues of affected joints. Certolizumab pegol (CZP is an Fc-free, PEGylated anti-TNFα monoclonal antibody. CZP has unique properties that differ from other available TNFα inhibitors by virtue of its lack of an Fc region, which minimizes potential Fc-mediated effects, and its PEGylation, which improves drug pharmacokinetics and bioavailability. It has been shown in clinical trials that CZP improves patient outcomes and reduces inflammation in the sacroiliac joints and spine in both ankylosing spondylitis and nonradiographic axial spondyloarthropathies. These data support CZP as a treatment option for axial spondyloarthropathies. Keywords: axial spondyloarthropathy, certolizumab pegol, anti-tumor necrosis factor-alpha, therapy
Axial elongation following prolonged near work in myopes and emmetropes.
Woodman, Emily C; Read, Scott A; Collins, Michael J; Hegarty, Katherine J; Priddle, Scott B; Smith, Josephine M; Perro, Judd V
2011-05-01
To investigate the influence of a period of sustained near work upon axial length in groups of emmetropes (EMM) and myopes. Forty young adult subjects (20 myopes and 20 emmetropes) were recruited for the study. Myopes were further classified as early onset (EOM), late onset (LOM), stable (SM) or progressing (PM) subgroups. Axial length was measured with the IOLMaster instrument before, immediately after and then again 10 min after a continuous 30 min near task of 5 D accommodation demand. Measures of distance objective refraction were also collected. Significant changes in axial length were observed immediately following the near task. EOM axial length elongated on average by 0.027±0.021 mm, LOM by 0.014±0.020 mm, EMM by 0.010±0.015 mm, PM by 0.031±0.022 mm and SM by 0.014±0.018 mm. At the conclusion of the 10 min regression period, axial length measures were not significantly different from baseline values. Axial elongation was observed following a prolonged near task. Both EOM and PM groups showed increases in axial length that were significantly greater than emmetropes.
Receiver function estimated by maximum entropy deconvolution
吴庆举; 田小波; 张乃铃; 李卫平; 曾融生
2003-01-01
Maximum entropy deconvolution is presented to estimate receiver function, with the maximum entropy as the rule to determine auto-correlation and cross-correlation functions. The Toeplitz equation and Levinson algorithm are used to calculate the iterative formula of error-predicting filter, and receiver function is then estimated. During extrapolation, reflective coefficient is always less than 1, which keeps maximum entropy deconvolution stable. The maximum entropy of the data outside window increases the resolution of receiver function. Both synthetic and real seismograms show that maximum entropy deconvolution is an effective method to measure receiver function in time-domain.
Brusov, Peter; Brusov, Pavel
2009-05-01
The whole collective mode spectrum in axial and planar phases of superfluid 3He with dispersion corrections is calculated for the first time. In axial A-phase the degeneracy of clapping modes depends on the direction of the collective mode momentum k with respect to the vector l (mutual orbital moment of Cooper pairs), namely: the mode degeneracy remains the same as in case of zero momentum k for k‖ l only. For any other directions there is a threefold splitting of these modes, which reaches maximum for k ⊥ l. In planar 2 D-phase, which exists in the magnetic field (at H> H C ) we find that for clapping modes the degeneracy depends on the direction of the collective mode momentum k with respect to the external magnetic field H, namely: the mode degeneracy remains the same as in case of zero momentum k for k‖ H only. For any other directions different from this one (for example, for k ⊥ H) there is twofold splitting of these modes. The obtained results imply that new interesting features can be observed in ultrasound experiments in axial and planar phases: the change of the number of peaks in ultrasound absorption into clapping mode. One peak, observed for these modes by Ling et al. (J. Low Temp. Phys. 78:187, 1990), will split into two peaks in a planar phase and into three peaks in an axial phase under the change of ultrasound direction with respect to the external magnetic field H in a planar phase and with respect to the vector l in an axial phase. In planar phase, some Goldstone modes in the magnetic field become massive (quasi-Goldstone) and have a similar twofold splitting under the change of ultrasound direction with respect to the external magnetic field H. The obtained results as well will be useful under interpretation of the ultrasound experiments in axial and planar phases of superfluid 3He.
Maximum Power from a Solar Panel
Michael Miller
2010-01-01
Full Text Available Solar energy has become a promising alternative to conventional fossil fuel sources. Solar panels are used to collect solar radiation and convert it into electricity. One of the techniques used to maximize the effectiveness of this energy alternative is to maximize the power output of the solar collector. In this project the maximum power is calculated by determining the voltage and the current of maximum power. These quantities are determined by finding the maximum value for the equation for power using differentiation. After the maximum values are found for each time of day, each individual quantity, voltage of maximum power, current of maximum power, and maximum power is plotted as a function of the time of day.
Yeow, C H; Lee, P V S; Goh, J C H
2010-01-19
Anterior tibial loading is a major factor involved in the anterior cruciate ligament (ACL) injury mechanism during ski impact landing. We sought to investigate the direct contribution of axial impact compressive load to anterior tibial load during simulated ski landing impact of intact knee joints without quadriceps activation. Twelve porcine knee specimens were procured. Four specimens were used as non-impact control while the remaining eight were mounted onto a material-testing system at 70 degrees flexion and subjected to simulated landing impact, which was successively repeated with incremental actuator displacement. Four specimens from the impacted group underwent pre-impact MRI for tibial plateau angle measurements while the other four were subjected to histology and microCT for cartilage morphology and volume assessment. The tibial plateau angles ranged from 29.4 to 38.8 degrees . There was a moderate linear relationship (Y=0.16X; R(2)=0.64; p<0.001) between peak axial impact compressive load (Y) and peak anterior tibial load (X). The anterior and posterior regions in the impacted group sustained surface cartilage fraying, superficial clefts and tidemark disruption, compared to the control group. MicroCT scans displayed visible cartilage deformation for both anterior and posterior regions in the impacted group. Due to the tibial plateau angle, increased axial impact compressive load can directly elevate anterior tibial load and hence contribute to ACL failure during simulated landing impact. Axial impact compressive load resulted in shear cartilage damage along anterior-posterior tibial plateau regions, due to its contribution to anterior tibial loading. This mechanism plays an important role in elevating ACL stress and cartilage deformation during impact landing.
Shape Manifestation of Respiration in the Axial System
Eliška Slawiková
2014-07-01
Full Text Available Shape Manifestation of Respiration in the Axial System The aim of the study was to evaluate the effect of respiration on the shape changes of the axial system. Our approach focuses more on the analysis of respiratory function and their implementation within the complex axial system – the trunk. The results of this pilot study will use as evidence for further study of relationship between respiration and physiotherapy. Now we are looking for an answer to the question, at what level of the human body reflected the influence of respiration and its use in physiotherapy. This pilot study was attended by two women and one man aged 25–40 years, who were not selected for the study according to predetermined conditions. The same characteristic features of all three prarticipants were sedentary job connected with excessive mental strain, occasional low back pain (usually after a long sitting and the absence of acute or chronic respiratory diseases. Another common feature of the participants was the absence of structural changes in the spine. During the experiment was monitored maximum inhalation and maximum exhalation, and respiratory maneuver Kapalabhati, often used as one of the basic yoga breathing exercises. To detect trunk movement during the respiratory maneuver, we opted for a Qualysis – 3D torso topography. At the same time spirometer panned changes in volume over time, both exhaled and inhaled air. The purpose of this study was to assess symptoms and implementation of respiratory maneuvers in the axial system, particularly the chest and abdominal area. During the experiment, we followed the differences in reaction of the chest and abdomen in respiratory maneuver in the direction vertical, antero-posterior and lateral. The difference in these indicators at different phases of the respiratory maneuver confirms our assumption of the possibility of influencing the selected folders axial system through appropriately selected respiratory maneuver
Bhoi, P.R. [Department of Mechanical Engineering, L and T-Sargent and Lundy Limited, L and T Energy Centre, Near Chhani Jakat Naka, Baroda 390 002 (India); Channiwala, S.A. [Department of Mechanical Engineering, Sardar Vallabhbhai National Institute of Technology, Deemed University, Ichchhanath, Surat 395 007, Gujarat (India)
2009-03-15
This paper presents the emission characteristics and axial flame temperature distribution of producer gas fired premixed burner. The producer gas fired premixed burner of 150 kW capacity was tested on open core throat less down draft gasifier system in the present study. A stable and uniform flame was observed with this burner. An instrumented test set up was developed to evaluate the performance of the burner. The conventional bluff body having blockage ratio of 0.65 was used for flame stabilization. With respect to maximum flame temperature, minimum pressure drop and minimum emissions, a swirl angle of 60 seems to be optimal. The experimental results also showed that the NO{sub x} emissions are inversely proportional to swirl angle and CO emissions are independent of swirl angle. The minimum emission levels of CO and NO{sub x} are observed to be 0.167% and 384 ppm respectively at the swirl angle of 45-60 . The experimental results showed that the maximum axial flame temperature distribution was achieved at A/F ratio of 1.0. The adiabatic flame temperature of 1653 C was calculated theoretically at A/F ratio of 1.0. Experimental results are in tune with theoretical results. It was also concluded that the CO and UHC emissions decreases with increasing A/F ratio while NO{sub x} emissions decreases on either side of A/F ratio of 1.0. (author)
Tensile Property of Bi-axial Warp Knitted Structure
沈为
2003-01-01
The tensile property of bi-axial warp knitted fabrics is tested and compared with that of the plain weave fabric. The results show that there are obvious differences between the tensile property of a bi-axial warp knitted fabric and that of a plain weave fabric.The former can give fuller play to the property of a high modulus yarn than the latter. The tensile strength of a bi-axial warp knitted fabric is linear with the number of yarns in the direction of force.
The axial charges of the hidden-charm pentaquark states
Wang, Guang-Juan; Zhu, Shi-Lin
2016-01-01
With the chiral quark model, we have calculated the axial charges of the pentaquark states with $(I,I_3)=(\\frac{1}{2},\\frac{1}{2})$ and $J^{P}=\\frac{1}{2}^{\\pm},\\frac{3}{2}^{\\pm},\\frac{5}{2}^{\\pm}$. The $P_c$ states with the same $J^P$ quantum numbers but different color-spin-flavor configurations have very different axial charges, which encode important information on their underlying structures. For some of the $J^{P}=\\frac{3}{2}^{\\pm}$ or $\\frac{5}{2}^{\\pm}$ pentaquark states, their axial charges are much smaller than that of the proton.
Dynamic Analysis of Axial Magnetic Forces for DVD Spindle Motors
2000-01-01
The axial magnetic force, induced by the complicated flux linkage distribution from rotor magnet and stator slotted, is constructed by different relative heights and calculated by 3D finite element method (FEM) to analyze the dynamic characteristics for a DVD spindle motor. The axial magnetic force is designed to provide an axial stiffness and govern the natural frequency of the dynamic performance. According to the simulation results and experimental measurements, the dynamic behaviors are significantly improved with a variation of relative height of rotor magnet and stator slotted on a DVD spindle motor.
Gravitational waves from the axial perturbations of hyperon stars
Wen De-Hua; Yan Jing; Liu Xue-Mei
2012-01-01
The eigen-frequencies of the axial w-mode oscillations of hyperon stars are examined.It is shown that as the appearance of hyperons softens the equation of state of the super-density matter,the frequency of gravitational waves from the axial w-mode of hyperon star becomes smaller than that of a traditional neutron star at the same stellar mass.Moreover,the eigenfrequencies of hyperon stars also have scaling universality.It is shown that the EURO thirdgeneration gravitational-wave detector has the potential to detect the gravitational-wave signal emitted from the axial w-mode oscillations of a hyperon star.
Dispositivos de asistencia ventricular de tipo axial
Albert Miralles Cassina
2009-04-01
Full Text Available El uso de dispositivos de asistencia ventricular se ha ido extendiendo en las últimas décadas. La mejora de los resultados ha ido acompañada del diseño de nuevos aparatos más pequeños y eficientes como son las bombas de flujo axial. las características técnicas básicas de estos dispositivos se hallan en la generación de un flujo continuo unidireccional conseguido mediante sistemas de turbina que obtienen su alimentación de una fuente eléctrica. Las ventajas principales de estos dispositivos son: su facilidad de implantación por su tamaño reducido, su prolongada durabilidad gracias a su sencillo diseño y su eficiencia energética al utilizar energía eléctrica. Su utilidad se ha podido demostrar en diferentes indicaciones de asistencia circulatoria mecánica, como en el caso de puente al trasplante o dispositivo de recuperación miocárdica, si bien donde radica más interés es en su uso como sistemas de asistencia circulatoria mecánica definitiva. Existe una variedad de modelos de diversos diseños. Son dispositivos que permiten soporte normalmente univentricular izquierdo, que se implantan en el tórax con cánula de entrada a nivel ventricular y cánula de salida a nivel aórtico. En este artículo se efectúa una descripción de los principales sistemas disponibles en la actualidad, comentando las características técnicas, ventajas e inconvenientes y un resumen de la experiencia existente.
Revealing atropisomer axial chirality in drug discovery.
LaPlante, Steven R; Edwards, Paul J; Fader, Lee D; Jakalian, Araz; Hucke, Oliver
2011-03-07
An often overlooked source of chirality is atropisomerism, which results from slow rotation along a bond axis due to steric hindrance and/or electronic factors. If undetected or not managed properly, this time-dependent chirality has the potential to lead to serious consequences, because atropisomers can be present as distinct enantiomers or diastereoisomers with their attendant different properties. Herein we introduce a strategy to reveal and classify compounds that have atropisomeric chirality. Energy barriers to axial rotation were calculated using quantum mechanics, from which predicted high barriers could be experimentally validated. A calculated rotational energy barrier of 20 kcal mol(-1) was established as a suitable threshold to distinguish between atropisomers and non-atropisomers with a prediction accuracy of 86%. This methodology was applied to subsets of drug databases in the course of which atropisomeric drugs were identified. In addition, some drugs were exposed that were not yet known to have this chiral attribute. The most valuable utility of this tool will be to predict atropisomerism along the drug discovery pathway. When used in concert with our compound classification scheme, decisions can be made during early discovery stages such as "hit-to-lead" and "lead optimization," to foresee and validate the presence of atropisomers and to exercise options of removing, further stabilizing, or rendering the chiral axis of interest more freely rotatable via SAR design, thereby decreasing this potential liability within a compound series. The strategy can also improve drug development plans, such as determining whether a drug or series should be developed as a racemic mixture or as an isolated single compound. Moreover, the work described herein can be extended to other chemical fields that require the assessment of potential chiral axes.
Yasuyuki Nishi
2016-01-01
Full Text Available We proposed a portable and ultra-small axial flow hydraulic turbine that can generate electric power comparatively easily using the low head of open channels such as existing pipe conduits or small rivers. In addition, we proposed a simple design method for axial flow runners in combination with the conventional one-dimensional design method and the design method of axial flow velocity uniformization, with the support of three-dimensional flow analysis. Applying our design method to the runner of an ultra-small axial flow hydraulic turbine, the performance and internal flow of the designed runner were investigated using CFD analysis and experiment (performance test and PIV measurement. As a result, the runners designed with our design method were significantly improved in turbine efficiency compared to the original runner. Specifically, in the experiment, a new design of the runner achieved a turbine efficiency of 0.768. This reason was that the axial component of absolute velocity of the new design of the runner was relatively uniform at the runner outlet in comparison with that of the original runner, and as a result, the negative rotational flow was improved. Thus, the validity of our design method has been verified.
Axial electron channeling statistical method of site occupancy determination
YE; Jia
2001-01-01
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Rawat, Roopa; Agrawal, Neha; Patil, Nilesh S.
2017-01-01
Since 1984 the diagnosis of ankylosing spondylitis (AS) has been based upon the modified New York (mNY) criteria with mandatory presence of radiographic sacroiliitis, without which the diagnosis is not tenable. However, it may take years or decades for radiographic sacroiliitis to develop delaying the diagnosis for long periods. It did not matter in the past because no effective treatment was available. However, with the availability of a highly effective treatment, namely, tumour necrosis factor-α inhibitors (TNFi), the issue of early diagnosis of AS acquired an urgency. The Assessment of SpondyloArthritis International Society (ASAS) classification criteria published in 2009 was a significant step towards this goal. These criteria described an early stage of the disease where sacroiliitis was demonstrable only on MRI but not on standard radiograph. Therefore, this stage of the disease was labelled “nonradiographic axial SpA” (nr-axSpA). But questions have been raised if, in search of early diagnosis, specificity was compromised. The Federal Drug Administration (FDA, USA) withheld approval for the use of TNFi in patients with nr-axSpA because of issues related to the specificity of these criteria. This review attempts to clarify some of these aspects of the nr-axSpA-AS relationship and also tries to answer the question whether ASAS classifiable radiographic axial spondyloarthritis (r-axSpA) term can be interchangeably used with the term AS. PMID:28555158
Pektaş, Ömer; Tönük, Ergin
2014-11-01
At the interface between the jawbone and the roots of natural teeth, a thin, elastic, shock-absorbing tissue, called the periodontal ligament, forms a cushion which provides certain flexibility under mechanical loading. The dental restorations supported by implants, however, involve comparatively rigid connections to the jawbone. This causes overloading of the implant while bearing functional loading together with neighboring natural teeth, which leads to high stresses within the implant system and in the jawbone. A dental implant, with resilient components in the upper structure (abutment) in order to mimic the mechanical behavior of the periodontal ligament in the axial direction, was designed, analyzed in silico, and produced for mechanical testing. The aims of the design were avoiding high levels of stress, loosening of the abutment connection screw, and soft tissue irritations. The finite element analysis of the designed implant revealed that the elastic abutment yielded a similar axial mobility with the natural tooth while keeping stress in the implant at safe levels. The in vitro mechanical testing of the prototype resulted in similar axial mobility predicted by the analysis and as that of a typical natural tooth. The abutment screw did not loosen under repeated loading and there was no static or fatigue failure.
Su, Guoshao; Feng, Xiating; Wang, Jinhuan; Jiang, Jianqing; Hu, Lihua
2017-08-01
During deep underground excavation, dynamic ejection failure of a highly stressed rock mass near an excavated boundary is easily triggered by a dynamic disturbance in the tunnel axial direction, induced by blasting on the tunnel face. Such a dynamic ejection failure is usually called remotely triggered rockburst, and it poses a threat to underground construction. To clarify the characteristics of remotely triggered rockburst, the development of remotely triggered rockbursts of granite rock specimens was investigated using an improved true-triaxial test system. Experimental results show that with increasing static Z-direction stress (i.e., in situ tangential stress on the cross section of the tunnel), rockburst is triggered more easily and the kinetic energy of ejected fragments increases. Under other constant static stresses and dynamic disturbance, with increasing horizontal stress including X-direction stress (i.e., in situ axial stress) or Y-direction stress (i.e., in situ radial stress on the cross section of the tunnel), rockburst is more difficult to trigger and the kinetic energy of the ejected fragments decreases. Under constant static stresses, once the amplitude and frequency of the dynamic loading exceed their thresholds, the rockburst intensity increases rapidly and the rockburst can be triggered much more easily with small increments of the amplitude and frequency. Furthermore, Z-direction strain increases during the dynamic disturbance process, indicating that the ultimate energy-storage capacity of the specimen decreases with increasing damage. When the elastic strain energy is greater than the ultimate energy-storage capacity of the damaged specimen, part of the residual elastic energy is converted into kinetic energy of the ejected fragments.
Effect of axial groove and resin luting cements on the retention of complete cast metal crowns
K Rajkumar
2009-01-01
Full Text Available Background : The design of the tooth preparation and the cementing medium are important consid-erations in the retention of crowns and fixed partial dentures. The purpose of this invitro study was to determine the effect of axial groove on the retention of complete cast metal crowns using two resin luting cements. Methods: Forty freshly extracted intact human molar teeth were prepared in their long axis to receive complete cast metal crowns. The specimens were randomly divided into two groups (one control and one study group. An axial groove of uniform size and shape was made on the prepared teeth under the study group. Axial surface area of prepared teeth specimens was measured. Complete cast metal crowns were fabricated for each specimen. Specimens of each group were divided into subgroups of 10 samples and were cemented with two resin luting cements, RelyX Unicem® and Calibra®, re-spectively. The cemented crowns were loaded in tension using a Universal Instron testing machine. The maximal tensile strength was recorded. Data were compared using the Mann-Whitney U test (α=0.05. Results: No significant differences in the tensile stress values were noted between the control (mean: 5.76±0.392 MPa and study (mean: 5.93±0.751 MPa groups cemented with RelyX Unicem. No sig-nificant differences in the tensile stress values were noted between the control (mean: 4.92±0.641 MPa and study (mean: 5.15 ±0.478 MPa groups cemented with Calibra. However, significant dif-ference in the tensile stress values was found between the two resin cements in the control and study groups. Conclusion: Axial groove placed in tooth preparations for resin bonded complete cast metal crowns had no statistically significant effect on retention. The use of (RelyX Unicem® yielded greater reten-tion values when compared to Calibra®.
Investigation of the turbulent swirl flow in pipe generated by axial fans using PIV and LDA methods
Čantrak Đorđe S.
2015-01-01
Full Text Available In this paper is presented experimental investigation of the turbulent swirl flow in pipe generated by axial fans. Two various models of industrial axial fans are used. One of these is axial fan W30, model AP 400, Minel, Serbia and has seven blades and outer diameter 0.397m. Second axial fan SP30 is model TGT/2-400-6, S&P, Spain, has six blades and outer diameter 0.386m. This results with greater clearance in the second case. Blades were adjusted for both fans at the angle of 30° at the outer diameter. Test rig length is 27.74-D, where D is average inner diameter app. 0.4 m. Measurements are performed in two measuring sections downstream the axial fans (z/D = 3.35 and z/D = 26.31 with one-component laser Doppler anemometry (LDA system and stereo particle image velocimetry (SPIV. Obtained Reynolds numbers, calculated on the basis of the average axial velocity (Um in the first measuring section are for fan SP30 Re = 226757, while for fan W30 Re = 254010. Integral flow parameters are determined such as average circulation and swirl number. Significant downstream axial velocity transformation occurs for both fans, while circumferential velocity is decreased, but non-dimensional velocity profile remains the same. Circumferential velocity distribution for both fans in the central zone corresponds to the solid body, while in r/R > 0.4, where D = 2R, distribution is more uniform. Radial velocity in the case of fan SP30 has almost zero values in the measuring section z/D = 3.35, while its values are significantly increased in the downstream section with the maximum in the vortex core region. On the contrary radial velocity decreases downstream for fan W30 and has also maximum value in the vortex core region for both measuring sections. Level of turbulence, skewness and flatness factors are calculated on the basis of the experimental data. The highest levels of turbulence for circumferential velocity are reached in the vortex core region for both fans
Radial breathing mode of carbon nanotubes subjected to axial pressure.
Lei, Xiao-Wen; Ni, Qing-Qing; Shi, Jin-Xing; Natsuki, Toshiaki
2011-08-11
In this paper, a theoretical analysis of the radial breathing mode (RBM) of carbon nanotubes (CNTs) subjected to axial pressure is presented based on an elastic continuum model. Single-walled carbon nanotubes (SWCNTs) are described as an individual elastic shell and double-walled carbon nanotubes (DWCNTs) are considered to be two shells coupled through the van der Waals force. The effects of axial pressure, wave numbers and nanotube diameter on the RBM frequency are investigated in detail. The validity of these theoretical results is confirmed through the comparison of the experiment, calculation and simulation. Our results show that the RBM frequency is linearly dependent on the axial pressure and is affected by the wave numbers. We concluded that RBM frequency can be used to characterize the axial pressure acting on both ends of a CNT.
The geometrical theory of diffraction for axially symmetric reflectors
Rusch, W.; Sørensen, O.
1975-01-01
The geometrical theory of diffraction (GTD) (cf. [1], for example) may be applied advantageously to many axially symmetric reflector antenna geometries. The material in this communication presents analytical, computational, and experimental results for commonly encountered reflector geometries...
Time Domain Terahertz Axial Computed Tomography Non Destructive Evaluation Project
National Aeronautics and Space Administration — We propose to demonstrate key elements of feasibility for a high speed automated time domain terahertz computed axial tomography (TD-THz CT) non destructive...
Open-Axial-Field Magnet at ISR intersection I8
1979-01-01
This axial field spectrometer left the central collision region unobstructed in order to ease analysis of secondary particles emitted at large angle. The ISR circulating beams were passing through a hole in the magnet poles.
Axial mesodermal dysplasia complex: a new case with parental consanguinity.
Mota, C R; Azevedo, M; Rocha, G; Manuela, F; Coelho, R; Lima, M R
2000-01-01
A female is described with axial mesodermal dysplasia complex (AMDC) born to a consanguineous couple. This is thought to be the first description of a patient with AMDC born to consanguineous parents.
Axial Stringy System of the Kerr Spinning Particle
Burinskii, A
2004-01-01
The structure of classical spinning particle based on the Kerr-Newman black hole (BH) solution is investigated. For large angular momentum, $|a|>>m$, the BH horizons disappear exposing a naked ringlike source which is a circular relativistic string. It was shown recently that electromagnetic excitations of this string lead to the appearance of an extra axial stringy system which consists of two half-infinite strings of opposite chirality. In this paper we consider the relation of this stringy system to the Dirac equation. We also show that the axial strings are the Witten superconducting strings and describe their structure by the Higgs field model where the Higgs condensate is used to regularize axial singularity. We argue that this axial stringy system may play the role of a classical carrier of the wave function.
Time Domain Terahertz Axial Computed Tomography Non Destructive Evaluation Project
National Aeronautics and Space Administration — In this Phase 2 project, we propose to develop, construct, and deliver to NASA a computed axial tomography time-domain terahertz (CT TD-THz) non destructive...
Uniform Decay for Solutions of an Axially Moving Viscoelastic Beam
Kelleche, Abdelkarim, E-mail: kellecheabdelkarim@gmail.com [Université des Sciences et de la Technologie Houari Boumediene, Faculté des Mathématiques (Algeria); Tatar, Nasser-eddine, E-mail: tatarn@Kfupm.edu.sa [King Fahd University of Petroleum and Minerals, Department of Mathematics and Statistics (Saudi Arabia)
2017-06-15
The paper deals with an axially moving viscoelastic structure modeled as an Euler–Bernoulli beam. The aim is to suppress the transversal displacement (transversal vibrations) that occur during the axial motion of the beam. It is assumed that the beam is moving with a constant axial speed and it is subject to a nonlinear force at the right boundary. We prove that when the axial speed of the beam is smaller than a critical value, the dissipation produced by the viscoelastic material is sufficient to suppress the transversal vibrations. It is shown that the rate of decay of the energy depends on the kernel which arise in the viscoelastic term. We consider a general kernel and notice that solutions cannot decay faster than the kernel.
Axial Anomaly in Lattice Abelian Gauge Theory in Arbitrary Dimensions
Fujiwara, T; Wu, K; Fujiwara, Takanori; Suzuki, Hiroshi; Wu, Ke
1999-01-01
Axial anomaly of lattice abelian gauge theory in hyper-cubic regular lattice in arbitrary even dimensions is investigated by applying the method of exterior differential calculus. The topological invariance, gauge invariance and locality of the axial anomaly determine the explicit form of the topological part. The anomaly is obtained up to a multiplicative constant for finite lattice spacing and can be interpreted as the Chern character of the abelian lattice gauge theory.
Axially symmetric volume constrained anisotropic mean curvature flow
Palmer, Bennett
2011-01-01
We study the long time existence theory for a non local flow associated to a free boundary problem for a trapped non liquid drop. The drop has free boundary components on two horizontal plates and its free energy is anisotropic and axially symmetric. For axially symmetric initial surfaces with sufficiently large volume, we show that the flow exists for all time. Numerical simulations of the curvature flow are presented.
Axial myopia in computed and magnetic resonance tomography
Beyer-Enke, S.A.; Goerich, J.; Gamroth, A.
1987-08-01
The case of a 44-year old woman suffering from amblyopia on the left eye with unilateral proptosis caused by axial (progressive) myopia is presented. The clinical and radiological findings were discussed in reference to the literature. The diagnosis was established by ruling out neoplastic, inflammatory or endocrine causes for the exophtalmos. CT and MR scans revealed an enlarged left globe without evidence of orbital masses. The findings were regarded as typical for the diagnosis at axial myopia.
Watson's theorem and the $N\\Delta(1232)$ axial transition
Alvarez-Ruso, L; Nieves, J; Vacas, M J Vicente
2016-01-01
We present a new determination of the $N\\Delta$ axial form factors from neutrino induced pion production data. For this purpose, the model of Hernandez et al., Phys. Rev. D76, 033005 (2007) is improved by partially restoring unitarity. This is accomplished by imposing Watson's theorem on the dominant vector and axial multipoles. As a consequence, a larger $C_5^A(0)$, in good agreement with the prediction from the off-diagonal Goldberger-Treiman relation, is now obtained.
Method to Measure Tone of Axial and Proximal Muscle
2011-01-01
The control of tonic muscular activity remains poorly understood. While abnormal tone is commonly assessed clinically by measuring the passive resistance of relaxed limbs1, no systems are available to study tonic muscle control in a natural, active state of antigravity support. We have developed a device (Twister) to study tonic regulation of axial and proximal muscles during active postural maintenance (i.e. postural tone). Twister rotates axial body regions relative to each other about the ...
Axially astigmatic surfaces: different types and their properties
Malacara-Doblado, Daniel; Malacara-Hernandez, Daniel; Garcia-Marquez, Jorge L.
1996-12-01
Axially astigmatic surfaces have different curvatures in orthogonal diameters. Toroidal and spherocylindrical optical surfaces are two mathematically different special cases of axially astigmatic surfaces as noted by Menchaca and Malacara (1986), but they are almost identical in the vicinity of the optical axis. The different between these two surfaces increases when the distance to the optical axis increases. We study the general properties of astigmatic surfaces and some special interesting cases.
Aerodynamics and combustion of axial swirlers
Fu, Yongqiang
A multipoint lean direct injection (LDI) concept was introduced recently in non-premixed combustion to obtain both low NOx emissions and good combustion stability. In this concept, a key feature is the injection of finely atomized fuel into the high-swirling airflow at the combustor dome that provides a homogenous, lean fuel-air mixture. In order to achieve the fine atomization and mixing of the fuel and air quickly and uniformly, a good swirler design should be studied. The focus of this dissertation is to investigate the aerodynamics and combustion of the swirling flow field in a multipoint Lean Direct Injector combustor. A helical axial-vaned swirler with a short internal convergent-divergent venturi was used. Swirlers with various vane angles and fuel nozzle insertion lengths have been designed. Three non-dimensional parameter effects on non-reacting, swirling flow field were studied: swirler number, confinement ratio and Reynolds number. Spray and combustion characteristics on the single swirler were studied to understand the mechanism of fuel-air mixing in this special configuration. Multi-swirler interactions were studied by measuring the confined flow field of a multipoint swirler array with different configurations. Two different swirler arrangements were investigated experimentally, which include a co-swirling array and a counter-swirling array. In order to increase the range of stability of multipoint LDI combustors, an improved design were also conducted. The results show that the degree of swirl and the level of confinement have a clear impact on the mean and turbulent flow fields. The swirling flow fields may also change significantly with the addition of a variety of simulated fuel nozzle insertion lengths. The swirler with short insertion has the stronger swirling flow as compared with the long insertion swirler. Reynolds numbers, with range of current study, will not alter mean and turbulent properties of generated flows. The reaction of the spray
The inverse maximum dynamic flow problem
BAGHERIAN; Mehri
2010-01-01
We consider the inverse maximum dynamic flow (IMDF) problem.IMDF problem can be described as: how to change the capacity vector of a dynamic network as little as possible so that a given feasible dynamic flow becomes a maximum dynamic flow.After discussing some characteristics of this problem,it is converted to a constrained minimum dynamic cut problem.Then an efficient algorithm which uses two maximum dynamic flow algorithms is proposed to solve the problem.
Physically-Based Reduced Order Modelling of a Uni-Axial Polysilicon MEMS Accelerometer
Sarah Zerbini
2012-10-01
Full Text Available In this paper, the mechanical response of a commercial off-the-shelf, uni-axial polysilicon MEMS accelerometer subject to drops is numerically investigated. To speed up the calculations, a simplified physically-based (beams and plate, two degrees of freedom model of the movable parts of the sensor is adopted. The capability and the accuracy of the model are assessed against three-dimensional finite element simulations, and against outcomes of experiments on instrumented samples. It is shown that the reduced order model provides accurate outcomes as for the system dynamics. To also get rather accurate results in terms of stress fields within regions that are prone to fail upon high-g shocks, a correction factor is proposed by accounting for the local stress amplification induced by re-entrant corners.
Physically-based reduced order modelling of a uni-axial polysilicon MEMS accelerometer.
Ghisi, Aldo; Mariani, Stefano; Corigliano, Alberto; Zerbini, Sarah
2012-10-17
In this paper, the mechanical response of a commercial off-the-shelf, uni-axial polysilicon MEMS accelerometer subject to drops is numerically investigated. To speed up the calculations, a simplified physically-based (beams and plate), two degrees of freedom model of the movable parts of the sensor is adopted. The capability and the accuracy of the model are assessed against three-dimensional finite element simulations, and against outcomes of experiments on instrumented samples. It is shown that the reduced order model provides accurate outcomes as for the system dynamics. To also get rather accurate results in terms of stress fields within regions that are prone to fail upon high-g shocks, a correction factor is proposed by accounting for the local stress amplification induced by re-entrant corners.
THE DYNAMIC BUCKLING OF ELASTIC-PLASTIC COLUMN SUBJECTED TO AXIAL IMPACT BY A RIGID BODY
Han Zhijun; Wang Jingchao; Cheng Guoqiang; Ma Hongwei; Zhang Shanyuan
2005-01-01
The dynamic buckling of an elastic-plastic column subjected to axial impact by a rigid body has been discussed in this paper. The whole traveling process of elastic-plastic waves under impact action is analyzed with the characteristics method. The regularity of stress changes in both column ends and the first separating time of a rigid body and column are obtained. By using the energy principle and taking into account the propagation and reflection of stress waves the lateral disturbance equation is derived and the power series solution is given. In addition,the critical buckling condition can be obtained from the stability analysis of the solution. By numerical computation and analysis, the relationship among critical velocity and impact mass,hardening modulus, and buckling time is given.
Maximum permissible voltage of YBCO coated conductors
Wen, J.; Lin, B.; Sheng, J.; Xu, J.; Jin, Z. [Department of Electrical Engineering, Shanghai Jiao Tong University, Shanghai (China); Hong, Z., E-mail: zhiyong.hong@sjtu.edu.cn [Department of Electrical Engineering, Shanghai Jiao Tong University, Shanghai (China); Wang, D.; Zhou, H.; Shen, X.; Shen, C. [Qingpu Power Supply Company, State Grid Shanghai Municipal Electric Power Company, Shanghai (China)
2014-06-15
Highlights: • We examine three kinds of tapes’ maximum permissible voltage. • We examine the relationship between quenching duration and maximum permissible voltage. • Continuous I{sub c} degradations under repetitive quenching where tapes reaching maximum permissible voltage. • The relationship between maximum permissible voltage and resistance, temperature. - Abstract: Superconducting fault current limiter (SFCL) could reduce short circuit currents in electrical power system. One of the most important thing in developing SFCL is to find out the maximum permissible voltage of each limiting element. The maximum permissible voltage is defined as the maximum voltage per unit length at which the YBCO coated conductors (CC) do not suffer from critical current (I{sub c}) degradation or burnout. In this research, the time of quenching process is changed and voltage is raised until the I{sub c} degradation or burnout happens. YBCO coated conductors test in the experiment are from American superconductor (AMSC) and Shanghai Jiao Tong University (SJTU). Along with the quenching duration increasing, the maximum permissible voltage of CC decreases. When quenching duration is 100 ms, the maximum permissible of SJTU CC, 12 mm AMSC CC and 4 mm AMSC CC are 0.72 V/cm, 0.52 V/cm and 1.2 V/cm respectively. Based on the results of samples, the whole length of CCs used in the design of a SFCL can be determined.
On the performance of circular concrete-filled high strength steel columns under axial loading
Mohamed Mahmoud El-Heweity
2012-06-01
Full Text Available This work presents a numerical study to investigate the performance of circular high-strength steel tubes filled with concrete (CFT under monotonic axial loading. A model is developed to implement the material constitutive relationships and non-linearity. Calibration against previous experimental data shows good agreement. A parametric study is then conducted using the model and compared with codes provisions. Strength and ductility of confined concrete are of primary concern. Variables considered are yield stress of steel tube and column diameter. The assessment of column performance is based on axial load carrying capacities and enhancements of both strength and ductility due to confinement. Two parameters namely strength enhancement factor (Kf and ductility index (μ are clearly defined and introduced for assessment. Results indicate that both concrete strength and ductility of CFT columns are enhanced but to different extents. The ductile behaviors are significantly evident. The increase in yield stress of steel tube has a minimal effect on concrete strength but pronounced effect on concrete ductility. However, reduction in ductility is associated with using high-tensile steel of Grade 70. The overall findings indicate that the use of high-strength tube in CFT columns is not promising. This finding may seriously be considered in seismic design.
Meso-Scale Damage Simulation of 3D Braided Composites under Quasi-Static Axial Tension
Zhang, Chao; Mao, Chunjian; Zhou, Yexin
2017-01-01
The microstructure of 3D braided composites is composed of three phases: braiding yarn, matrix and interface. In this paper, a representative unit-cell (RUC) model including these three phases is established. Coupling with the periodical boundary condition, the damage behavior of 3D braided composites under quasi-static axial tension is simulated by using finite element method based on this RUC model. An anisotropic damage model based on Murakami damage theory is proposed to predict the damage evolution of yarns and matrix; a damage-friction combination interface constitutive model is adopted to predict the interface debonding behavior. A user material subroutine (VUMAT) involving these damage models is developed and implemented in the finite element software ABAQUS/Explicit. The whole process of damage evolution of 3D braided composites under quasi-static axial tension with typical braiding angles is simulated, and the damage mechanisms are revealed in detail in the simulation process. The tensile strength properties of the braided composites are predicted from the calculated stress-strain curves. Numerical results agree with the available experiment data and thus validates the proposed damage analysis model. The effects of certain material parameters on the predicted stress-strain responses are also discussed by numerical parameter study.
Piezoelectric ZnO-CNT nanotubes under axial strain and electrical voltage
Zhang, Jin; Wang, Ruijie; Wang, Chengyuan
2012-09-01
This paper aims to study the mechanical responses of a piezoelectric composite nanotube subject to an axial strain and electrical voltage. The nanotubes are fabricated by coating carbon nanotubes (CNTs) with zinc oxide (ZnO) nanocrystal. The axial buckling of the ZnO-CNTs nanotubes (ZCNTs) is investigated by using a composite Euler beam model accounting for the piezoelectricity of the coating layer. Particular attention is paid to the strengthening effect of the core CNT and the effect of the piezoelectricity of the outer ZnO layer. Pre-buckling analysis is also conducted to study the static deformation prior to the buckling. Analytical solutions are obtained based on the theory of three-dimensional elasticity and piezoelectricity. In particular, a tensile radial stress is achieved at the ZnO-CNT interface, which tends to separate the ZnO layer from core CNT and may generate delamination in composite ZCNTs. The size-dependence and physical basis of such an interface stress is thus discussed in details for ZCNTs.
Stress tracking in thin bars by eigenstrain actuation
Schoeftner, J.; Irschik, H.
2016-11-01
This contribution focuses on stress tracking in slender structures. The axial stress distribution of a linear elastic bar is investigated, in particular, we seek for an answer to the following question: in which manner do we have to distribute eigenstrains, such that the axial stress in a bar is equal to a certain desired stress distribution, despite external forces or support excitations are present? In order to track a certain time- and space-dependent stress function, smart actuators, such as piezoelectric actuators, are needed to realize eigenstrains. Based on the equation of motion and the constitutive relation, which relate stress, strain, displacement and eigenstrains, an analytical solution for the stress tracking problem is derived. The starting point for the derivation of a solution for the stress tracking problem is a semi-positive definite integral depending on the error stress which is the difference between the actual stress and the desired stress. Our derived stress tracking theory is verified by two examples: first, a clamped-free bar which is harmonically excited is investigated. It is shown under which circumstances the axial stress vanishes at every location and at every time instant. The second example is a support-excited bar with end mass, where a desired stress profile is prescribed.
Axial blanket for 16NGF Angra 1 fuel type
Sadde, Luciano Martins; Faria, Eduardo Fernandes [Industrias Nucleares do Brasil (INB), Resende, RJ (Brazil)]. E-mails: sadde@inb.gov.br; faria@inb.gov.br; Sang-Keun You [Korea Nuclear Fuel Co. Ltd. (KNFC), Taejon (Korea, Republic of)]. E-mail: skyou@knfc.co.kr
2007-07-01
Angra-1, Kori-2 and Krsko are nuclear power plants with the same design. However, the fuel assemblies have some differences in design due to the countries strategies and the differences in the fabrication process. The 16NGF (16x16 Next Generation Fuel) was developed by INB, KNFC and Westinghouse in order to be used in these three nuclear power plants and the 'Axial Blanket' is one of the new features for the 16NGF design. The main purpose of the Axial Blanket Optimization study is to determine which axial blanket enrichment and length would provide the better fuel cycle cost benefit. All of the calculations were performed using Gadolinium as Burnable Absorber and solid pellets type for Axial Blanket. The results indicate 1.8 w/o U235 enrichment and 8 inches length as the best option of Axial Blanket from the fuel cycle cost benefit standpoint. The economy is about 1.8%. The difference in the reload cost in the range between 1.5 and 2.6 w/o U235 enrichment and for the 6 and 8 inches length is not so significant. Due that, from the Fq limit standpoint and also for longer cycle length requirements, a higher axial blanket enrichment (2.6 w/o) and shorter length (6 inches) is recommended. (author)
Reactive control of subsonic axial fan noise in a duct.
Liu, Y; Choy, Y S; Huang, L; Cheng, L
2014-10-01
Suppressing the ducted fan noise at low frequencies without varying the flow capacity is still a technical challenge. This study examines a conceived device consisting of two tensioned membranes backed with cavities housing the axial fan for suppression of the sound radiation from the axial fan directly. The noise suppression is achieved by destructive interference between the sound fields from the axial fan of a dipole nature and sound radiation from the membrane via vibroacoustics coupling. A two-dimensional model with the flow effect is presented which allows the performance of the device to be explored analytically. The air flow influences the symmetrical behavior and excites the odd in vacuo mode response of the membrane due to kinematic coupling. Such an asymmetrical effect can be compromised with off-center alignment of the axial fan. Tension plays an important role to sustain the performance to revoke the deformation of the membrane during the axial fan operation. With the design of four appropriately tensioned membranes covered by a cylindrical cavity, the first and second blade passage frequencies of the axial fan can be reduced by at least 20 dB. The satisfactory agreement between experiment and theory demonstrates that its feasibility is practical.
Axial scanning in confocal microscopy employing adaptive lenses (CAL).
Koukourakis, Nektarios; Finkeldey, Markus; Stürmer, Moritz; Leithold, Christoph; Gerhardt, Nils C; Hofmann, Martin R; Wallrabe, Ulrike; Czarske, Jürgen W; Fischer, Andreas
2014-03-10
In this paper we analyze the capability of adaptive lenses to replace mechanical axial scanning in confocal microscopy. The adaptive approach promises to achieve high scan rates in a rather simple implementation. This may open up new applications in biomedical imaging or surface analysis in micro- and nanoelectronics, where currently the axial scan rates and the flexibility at the scan process are the limiting factors. The results show that fast and adaptive axial scanning is possible using electrically tunable lenses but the performance degrades during the scan. This is due to defocus and spherical aberrations introduced to the system by tuning of the adaptive lens. These detune the observation plane away from the best focus which strongly deteriorates the axial resolution by a factor of ~2.4. Introducing balancing aberrations allows addressing these influences. The presented approach is based on the employment of a second adaptive lens, located in the detection path. It enables shifting the observation plane back to the best focus position and thus creating axial scans with homogeneous axial resolution. We present simulated and experimental proof-of-principle results.
Relationship Between Retinal Vein Occlusion and Axial Length
San-Chang Tsai
2003-09-01
Full Text Available This study examined whether axial length is a local risk factor for central retinal vein occlusion (CRVO and branch retinal vein occlusion (BRVO. The study group consisted of 40 patients with unilateral CRVO and 77 patients with unilateral BRVO. The control group included 67 individuals who matched the study group patients in age, systemic hypertension, and diabetes mellitus status. The axial lengths of affected and fellow eyes of patients and controls were measured using A-scan ultrasonography. The axial length of affected eyes was statistically significantly shorter than that of unaffected eyes in the BRVO group (p < 0.05 but not in the CRVO group (p = 0.05. There were also statistically significant differences in axial length between control eyes and affected eyes in both the CRVO group (p < 0.05 and BRVO group (p < 0.05. Thus, shorter axial length could be a risk factor for developing CRVO and BRVO. The axial lengths of affected eyes in retinal vein occlusion patients tend to be shorter than those of unaffected eyes, especially in BRVO patients.
Castillo, A.; Torres, M.; Ortiz, J. J.; Perusquia, R.; Hernandez, J. L.; Montes, J. L. [ININ, 52750 La Marquesa, Estado de Mexico (Mexico)]. e-mail: jacm@nuclear.inin.mx
2008-07-01
In the present work the preliminary results were obtained with the zoctli system whose purpose is the axial design of assembly of nuclear fuel under certain considerations. For the mentioned design well-know cells were already used and that they have been proven in diverse cycles of operation in the nuclear power plant of Laguna Verde. The design contemplates fuels assemblies of 10x10 and with 2 water channels. The assembly was distributed in 6 axial zones according to its structure. In order to take to end the optimization is was used the well-known technique like Path relinking and to find the group of previous solutions required by this technique uses the technical Taboo search. In order to work with Path relinking, 5 trajectories was taken in to account from a set of 5 previous solutions generated with theTaboo search, the update of the group of solutions is carried out in dynamic form. In the case of the Taboo search it was used a list of variable size, it was implement an aspiration approach, it was used the vector of frequencies and due to the cost of the evaluation of the objective function, only it was review 5% of the vicinity. For the objective function was considered the limit thermal, the axial profile of power, the effective multiplication factor and the margin of having turned off in cold. In order to prove the design system, it was used a balance cycle with a value of reference of 0.9928 for the effective multiplication factor that is equivalent to a produced energy of 10896 MWd/TU at the end of operation to full power. The designed assemblies were placed both in one of lots different from fresh assemblies on which it counts the referred cycle. At the end one a comparison with the results obtained with other techniques and under similar conditions is made. The results obtained until the moment show an appropriate performance of the system. It is possible to indicate that a small inconvenient is the amount of consumed resources of calculation during
Structure of the Anayet Permian basin (Axial Zone, Central Pyrenees)
Rodriguez, L.; Cuevas, J.; Tubía, J. M.
2012-04-01
The Anayet Permian basin was generated by strike-slip tectonics that opened subsident basins with pull-apart geometries in the western Spanish Axial Zone (between the Aragon and Tena valleys). A continental succession of Permian age, that represents the first post-variscan deposits in the area, fills the basin and covers discordantly Devonian to Carboniferous limestones, sandstones and slates. Permian deposits have been classically divided in four main detrital groups, with three basic volcanic episodes interbedded (Gisbert, 1984, Bixel, 1987): the Grey Unit (50-120 m, Estefanian to Kungurian) with slates, conglomerates, tobaceous slates, coal and pyroclastic deposits, the Transition Unit (50 m maximum) showing grey and red sandstones and lutites with oolitic limestones intercalated, the Lower Red Unit (250 m) composed of cross-bedded red sandstones and andesitic volcanic rocks at the top, and finally the Upper Red Unit (400 m minimum, top eroded) formed by three fining up megasequences of carbonates, red sandstones and lutites with lacustrine carbonates intercalated and alkali basalts at the top. Increasingly older rocks are found towards the western part of the basin, where its depocenter is located. South-vergent angular folds deform the Permian sedimentary succession. Fold axes are N115 °E-trending, almost horizontal and are characterized by a remarkably constant orientation. Folds exhibit a long limb dipping slightly to the north and a short vertical limb, occasionally reversed. In the Anayet basin four main folds, with a wavelength of 400 m, can be distinguished, two anticlines and two synclines, with minor folds associated. Related to the angular folds an axial plane foliation, E-trending and dipping 40 to 60° to the north, is developed in the lutites. The more competent rocks, conglomerates and breccias, only locally show a spaced fracture cleavage. No main thrusts have been detected in Permian rocks. However, minor scale decollements, usually low angle
Improvement of Axial Reflector Cross Section Generation Model for PWR Core Analysis
Shim, Cheon Bo; Lee, Kyung Hoon; Cho, Jin Young [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)
2016-10-15
This paper covers the study for improvement of axial reflector XS generation model. In the next section, the improved 1D core model is represented in detail. Reflector XS generated by the improved model is compared to that of the conventional model in the third section. Nuclear design parameters generated by these two XS sets are also covered in that section. Significant of this study is discussed in the last section. Two-step procedure has been regarded as the most practical approach for reactor core designs because it offers core design parameters quite rapidly within acceptable range. Thus this approach is adopted for SMART (System-integrated Modular Advanced Reac- Tor) core design in KAERI with the DeCART2D1.1/ MASTER4.0 (hereafter noted as DeCART2D/ MASTER) code system. Within the framework of the two-step procedure based SMART core design, various researches have been studied to improve the core design reliability and efficiency. One of them is improvement of reflector cross section (XS) generation models. While the conventional FA/reflector two-node model used for most core designs to generate reflector XS cannot consider the actual configuration of fuel rods that intersect at right angles to axial reflectors, the revised model reflects the axial fuel configuration by introducing the radially simplified core model. The significance of the model revision is evaluated by observing HGC generated by DeCART2D, reflector XS, and core design parameters generated by adopting the two models. And it is verified that about 30 ppm CBC error can be reduced and maximum Fq error decreases from about 6 % to 2.5 % by applying the revised model. Error of AO and axial power shapes are also reduced significantly. Therefore it can be concluded that the simplified 1D core model improves the accuracy of the axial reflector XS and leads to the two-step procedure reliability enhancement. Since it is hard for core designs to be free from the two-step approach, it is necessary to find
Analysis of Thermal Stresses and Strains Developing during the Heat Treatment of Windmill Shaft
Cebo-Rudnicka A.
2017-06-01
Full Text Available In the paper the results of evaluation of the temperature and stress fields during four cycles of the heat treatment process of the windmill shaft has been presented. The temperature field has been calculated from the solution to the heat conduction equation over the whole heat treatment cycles of the windmill shaft. To calculate the stress field an incremental method has been used. The relations between stresses and strains have been described by Prandtl-Reuss equation for the elastic-plastic body. In order to determine the changes in the temperature and stress fields during heat treatment of the windmill shaft self-developed software utilizing the Finite Element Method has been used. This software can also be used to calculate temperature changes and stress field in ingots and other axially symmetric products. In the mathematical model of heating and cooling of the shaft maximum values of the strains have been determined, which allowed to avoid the crack formation. The critical values of strains have been determined by using modified Rice and Tracy criterion.
Generalised maximum entropy and heterogeneous technologies
Oude Lansink, A.G.J.M.
1999-01-01
Generalised maximum entropy methods are used to estimate a dual model of production on panel data of Dutch cash crop farms over the period 1970-1992. The generalised maximum entropy approach allows a coherent system of input demand and output supply equations to be estimated for each farm in the sam
20 CFR 229.48 - Family maximum.
2010-04-01
... month on one person's earnings record is limited. This limited amount is called the family maximum. The family maximum used to adjust the social security overall minimum rate is based on the employee's Overall..., when any of the persons entitled to benefits on the insured individual's compensation would, except...
The maximum rotation of a galactic disc
Bottema, R
1997-01-01
The observed stellar velocity dispersions of galactic discs show that the maximum rotation of a disc is on average 63% of the observed maximum rotation. This criterion can, however, not be applied to small or low surface brightness (LSB) galaxies because such systems show, in general, a continuously
Duality of Maximum Entropy and Minimum Divergence
Shinto Eguchi
2014-06-01
Full Text Available We discuss a special class of generalized divergence measures by the use of generator functions. Any divergence measure in the class is separated into the difference between cross and diagonal entropy. The diagonal entropy measure in the class associates with a model of maximum entropy distributions; the divergence measure leads to statistical estimation via minimization, for arbitrarily giving a statistical model. The dualistic relationship between the maximum entropy model and the minimum divergence estimation is explored in the framework of information geometry. The model of maximum entropy distributions is characterized to be totally geodesic with respect to the linear connection associated with the divergence. A natural extension for the classical theory for the maximum likelihood method under the maximum entropy model in terms of the Boltzmann-Gibbs-Shannon entropy is given. We discuss the duality in detail for Tsallis entropy as a typical example.
Mokhtarikhoee, Sepideh; Jannesari, Alireza; Behroozi, Hamid; Mokhtarikhoee, Saeedeh
2008-01-01
Connectors in fixed partial dentures (FPDs) are the weakest areas and responsible for failure in most cases. Optimizing the design of connectors will lead to higher strength and better performance of all-ceramic FPDs. The aim of this study was to use the finite element method in order to simulate the effect of connector width on stress distribution in all-ceramic FPDs. Three 3-dimensional finite element models for a 3-unit FPD made of IPS-Empress 2 representing a lower first molar were created and a static load of 500 N was applied axially at mid pontic area. By choosing three different widths, 3 mm, 4 mm, 5 mm for connectors, three models I,II, and III for complete assembly of teeth and connectors were created. Maximum stress occurred in the connector area in all models. Compared to model I, stress decreased 24% in model III; so the wider connector lead to lower stress values. Connectors are the most regular area for the fracture in all-ceramic FPDs because of high concentration of stress. Decreasing the width of connector raises the stress and increases the risk for fracture. Also, maximum stress in bridges is less than half of the strength of IPS-Empress2 and no failure is expected for all cases. This in vitro study of 3-unit all ceramicFPDs made with IPS-Empress2 shows that an increase in the width of connector reduces the stress concentration and improves the likelihood of long-term prognosis. Also, IPS-Empress2 can be used in posterior regions in many cases.
Kai Yan
2015-01-01
Full Text Available A predictive model for droplet size and velocity distributions of a pressure swirl atomizer has been proposed based on the maximum entropy formalism (MEF. The constraint conditions of the MEF model include the conservation laws of mass, momentum, and energy. The effects of liquid swirling strength, Weber number, gas-to-liquid axial velocity ratio and gas-to-liquid density ratio on the droplet size and velocity distributions of a pressure swirl atomizer are investigated. Results show that model based on maximum entropy formalism works well to predict droplet size and velocity distributions under different spray conditions. Liquid swirling strength, Weber number, gas-to-liquid axial velocity ratio and gas-to-liquid density ratio have different effects on droplet size and velocity distributions of a pressure swirl atomizer.
Investigation of axial power gradients near a control rod tip
Loberg, John, E-mail: John.Loberg@fysast.uu.se [Uppsala University, Department of Physics and Astronomy, Division of Applied Nuclear Physics, Box 525, SE-75120 Uppsala (Sweden); Osterlund, Michael, E-mail: Michael.Osterlund@fysast.uu.se [Uppsala University, Department of Physics and Astronomy, Division of Applied Nuclear Physics, Box 525, SE-75120 Uppsala (Sweden); Bejmer, Klaes-Hakan, E-mail: Klaes-Hakan.Bejmer@vattenfall.com [Vattenfall Nuclear Fuel AB, Jaemtlandsgatan 99, 162 60 Vaellingby, Stockholm (Sweden); Blomgren, Jan, E-mail: Jan.Blomgren@vattenfall.com [Vattenfall Nuclear Fuel AB, Jaemtlandsgatan 99, 162 60 Vaellingby, Stockholm (Sweden); Kierkegaard, Jesper, E-mail: Jesper.Kierkegaar@vattenfall.com [Vattenfall Nuclear Fuel AB, Jaemtlandsgatan 99, 162 60 Vaellingby, Stockholm (Sweden)
2011-07-15
Highlights: > Pin power gradients near BWR control rod tips have been investigated. > A control rod tip is modeled in MCNP and compared to simplified 2D/3D geometry. > Small nodes increases pin power gradients; standard nodes underestimates gradients. > The MCNP results are validated against axial gamma scan of a controlled fuel pin. - Abstract: Control rod withdrawal in BWRs induces large power steps in the adjacent fuel assemblies. This paper investigates how well a 2D/3D method, e.g., CASMO5/SIMULATE5 computes axial pin power gradients adjacent to an asymmetrical control-rod tip in a BWR. The ability to predict pin power gradients accurately is important for safety considerations whereas large powers steps induced by control rod withdrawal can cause Pellet Cladding Interaction. The computation of axial pin power gradients axially around a control rod tip is a challenging task for any nodal code. On top of that, asymmetrical control rod handles are present in some BWR designs. The lattice code CASMO requires diagonal symmetry of all control rod parts. This introduces an error in computed pin power gradients that has been evaluated by Monte Carlo calculations. The results show that CASMO5/SIMULATE5, despite the asymmetrical control rod handle, is able to predict the axial pin power gradient within 1%/cm for axial nodal sizes of 15-3.68 cm. However, a nodal size of 3.68 cm still causes underestimations of pin power gradients compared with 1 cm nodes. Furthermore, if conventional node sizes are used, {approx}15 cm, pin power gradients can be underestimated by over 50% compared with 1 cm nodes. The detailed axial pin power profiles from MCNP are corroborated by measured gamma scan data on fuel rods irradiated adjacent to control rods.
Axial length as a risk factor to branch retinal vein occlusion
Timmerman, EA; deLavalette, VWR; vandenBrom, HJB
1997-01-01
Purpose: To determine whether axial length is a factor in branch retinal vein occlusion. Methods: Axial length measurements in a group of 24 patients with a unilateral branch retinal Vein occlusion were compared with the axial length measurements in a control group. axial length measurements were ta
Hernandez, P. [Lawrence Berkeley Lab., CA (United States)
1995-02-01
This paper is an expansion of engineering notes prepared in 1961 to address the question of how to wind circular coils so as to obtain the maximum axial field with the minimum volume of conductor. At the time this was a germain question because of the advent of superconducting wires which were in very limited supply, and the rapid push for generation of very high fields, with little concern for uniformity.
Effect of residual stress on peak cap stress in arteries.
Vandiver, Rebecca
2014-10-01
Vulnerable plaques are a subset of atherosclerotic plaques that are prone to rupture when high stresses occur in the cap. The roles of residual stress, plaque morphology, and cap stiffness on the cap stress are not completely understood. Here, arteries are modeled within the framework of nonlinear elasticity as incompressible cylindrical structures that are residually stressed through differential growth. These structures are assumed to have a nonlinear, anisotropic, hyperelastic response to stresses in the media and adventitia layers and an isotropic response in the intima and necrotic layers. The effect of differential growth on the peak stress is explored in a simple, concentric geometry and it is shown that axial differential growth decreases the peak stress in the inner layer. Furthermore, morphological risk factors are explored. The peak stress in residually stressed cylinders is not greatly affected by changing the thickness of the intima. The thickness of the necrotic layer is shown to be the most important morphological feature that affects the peak stress in a residually stressed vessel.
Haddad, H.; Dejean, C.; Henriques de Figueiredo, B.; Sargos, P.; Caron, J. [Departement de radiotherapie, institut Bergonie, centre regional de lutte contre le cancer de Bordeaux et du Sud-Ouest, 229, cours de l' Argonne, 33076 Bordeaux cedex (France); Stoeckle, E. [Departement de chirurgie, institut Bergonie, centre regional de lutte contre le cancer de Bordeaux et du Sud-Ouest, 229, cours de l' Argonne, 33076 Bordeaux cedex (France); Bui, B.N.; Italiano, A. [Departement d' oncologie medicale, institut Bergonie, centre regional de lutte contre le cancer de Bordeaux et du Sud-Ouest, 229, cours de l' Argonne, 33076 Bordeaux cedex (France); Gille, O. [Service d' orthopedie, groupe hospitalier Pellegrin, CHU de Bordeaux, place Amelie-Raba-Leon, 33076 Bordeaux cedex (France); Kantor, G. [Departement de radiotherapie, institut Bergonie, centre regional de lutte contre le cancer de Bordeaux et du Sud-Ouest, 229, cours de l' Argonne, 33076 Bordeaux cedex (France); Universite Victor-Segalen Bordeaux 2, 146, rue Leo-Saignat, 33076 Bordeaux cedex (France)
2011-08-15
Purpose. - To evaluate the feasibility of helical tomo-therapy intensity-modulated radiotherapy for the treatment of axial and para-spinal tumours. Patients and methods. - Fourteen consecutive patients with axial and para-spinal tumours at the Bergonie Institute between June 2007 and June 2009 were analysed. Various localizations were observed: four paravertebral tumours, five primitive vertebral tumours and six ilio-sacral or sacral tumours. Results. - The dose prescribed to the median of the planning target volume (PTV) varied from 45 to 68 Gy depending on histology. The maximum dose delivered to the PTV (D near max or D 2%) was 60.6 Gy (range 46.3-69.1). In the five cases where the tumour was located close to the spinal cord, the median value of D near max was 40.1 Gy (range 37.8-45.4). In the seven where the tumour was situated close to the cauda equina, the median value of D near max was 46.5 Gy (range 39.2-60). For two cases in whom the sciatic nerve was the nervous structure at risk, the D near max was 64.4 and 67 Gy. Six patients were in complete remission, six patients suffered a relapse at a median follow-up of 14.5 months (4-24), two died following local tumour progression and metastasis, tumoral stabilisation had been obtained in two patients. Treatment was well tolerated and was never interrupted in all patients. Conclusions. - Results from this preliminary series are encouraging, particularly concerning the good tolerance of this new intensity-modulated radiotherapy presently more available than proton therapy. (authors)
Development and Testing of an Axial Halbach Magnetic Bearing
Eichenberg, Dennis J.; Gallo, Christopher A.; Thompson, William K.
2006-01-01
The NASA Glenn Research Center has developed and tested a revolutionary Axial Halbach Magnetic Bearing. The objective of this work is to develop a viable non-contact magnetic thrust bearing utilizing Halbach arrays for all-electric flight, and many other applications. This concept will help to reduce harmful emissions, reduce the Nation s dependence on fossil fuels and mitigate many of the concerns and limitations encountered in conventional axial bearings such as bearing wear, leaks, seals and friction loss. The Axial Halbach Magnetic Bearing is inherently stable and requires no active feedback control system or superconductivity as required in many magnetic bearing designs. The Axial Halbach Magnetic Bearing is useful for very high speed applications including turbines, instrumentation, medical systems, computer memory systems, and space power systems such as flywheels. Magnetic fields suspend and support a rotor assembly within a stator. Advanced technologies developed for particle accelerators, and currently under development for maglev trains and rocket launchers, served as the basis for this application. Experimental hardware was successfully designed and developed to validate the basic principles and analyses. The report concludes that the implementation of Axial Halbach Magnetic Bearings can provide significant improvements in rotational system performance and reliability.
Method to measure tone of axial and proximal muscle.
Gurfinkel, Victor S; Cacciatore, Timothy W; Cordo, Paul J; Horak, Fay B
2011-12-14
The control of tonic muscular activity remains poorly understood. While abnormal tone is commonly assessed clinically by measuring the passive resistance of relaxed limbs, no systems are available to study tonic muscle control in a natural, active state of antigravity support. We have developed a device (Twister) to study tonic regulation of axial and proximal muscles during active postural maintenance (i.e. postural tone). Twister rotates axial body regions relative to each other about the vertical axis during stance, so as to twist the neck, trunk or hip regions. This twisting imposes length changes on axial muscles without changing the body's relationship to gravity. Because Twister does not provide postural support, tone must be regulated to counteract gravitational torques. We quantify this tonic regulation by the restive torque to twisting, which reflects the state of all muscles undergoing length changes, as well as by electromyography of relevant muscles. Because tone is characterized by long-lasting low-level muscle activity, tonic control is studied with slow movements that produce "tonic" changes in muscle length, without evoking fast "phasic" responses. Twister can be reconfigured to study various aspects of muscle tone, such as co-contraction, tonic modulation to postural changes, tonic interactions across body segments, as well as perceptual thresholds to slow axial rotation. Twister can also be used to provide a quantitative measurement of the effects of disease on axial and proximal postural tone and assess the efficacy of intervention.
Design and Simulation of Axial Flow Maglev Blood Pump
Huachun Wu
2011-03-01
Full Text Available The axial flow maglev blood pump (AFMBP has become a global research focus and emphasis for artificial ventricular assist device, which has no mechanical contact, mechanical friction, compact structure and light weight, can effectively solve thrombus and hemolysis. Magnetic suspension and impeller is two of the important parts in the axial flow maglev blood pump, and their structure largely determines the blood pump performance. The research adopts electromagnetic and fluid finite element analysis, and puts forward a method to design the magnetic suspension and impeller of axial flow blood pump, which tacks into account the small volume of axial blood pump. The magnetic bearing’s characteristics are evaluated by electromagnetic finite element analysis. The Blades have been designed by calculating aerofoil bone line, and make simulation analysis for different thicken ways of blade by Fluent software, and make a conclusion that the blade thickened with certain rules has better characteristics in the same conditions. The results will provide some guidance for design of axial flow maglev blood pump, and establish theoretical basis for application of the implantable artificial heart pump.
Light weakly coupled axial forces: models, constraints, and projections
Kahn, Yonatan; Krnjaic, Gordan; Mishra-Sharma, Siddharth; Tait, Tim M. P.
2017-05-01
We investigate the landscape of constraints on MeV-GeV scale, hidden U(1) forces with nonzero axial-vector couplings to Standard Model fermions. While the purely vector-coupled dark photon, which may arise from kinetic mixing, is a well-motivated scenario, several MeV-scale anomalies motivate a theory with axial couplings which can be UV-completed consistent with Standard Model gauge invariance. Moreover, existing constraints on dark photons depend on products of various combinations of axial and vector couplings, making it difficult to isolate the effects of axial couplings for particular flavors of SM fermions. We present a representative renormalizable, UV-complete model of a dark photon with adjustable axial and vector couplings, discuss its general features, and show how some UV constraints may be relaxed in a model with nonrenormalizable Yukawa couplings at the expense of fine-tuning. We survey the existing parameter space and the projected reach of planned experiments, briefly commenting on the relevance of the allowed parameter space to low-energy anomalies in π0 and 8Be∗ decay.
An Axial Vector Photon in a Mirror World
Sharafiddinov, Rasulkhozha S
2015-01-01
The unity of symmetry laws emphasizes, in the case of a mirror CP-even Dirac Lagrangian, the ideas of the left- and right-handed axial-vector photons referring to long- and short-lived bosons of true neutrality, respectively. Such a difference in lifetimes expresses the unidenticality of masses, energies and momenta of axial-vector photons of the different components. They define the unified field theory equation of C-odd particles with an integral spin. Together with a new equation of a theory of truly neutral particles with the half-integral spin, the latter reflects the availability in their nature of the second type of the local axial-vector gauge transformation responsible for origination in the Lagrangian of C-oddity of an interaction Newton component giving an axial-vector mass to all the interacting particles and fields. The mirror axial-vector mass, energy and momentum operators constitute a CP-invariant equation of quantum mechanics, confirming that each of them can individually influence on matter ...
Light Weakly Coupled Axial Forces: Models, Constraints, and Projections
Kahn, Yonatan; Mishra-Sharma, Siddharth; Tait, Tim M P
2016-01-01
We investigate the landscape of constraints on MeV-GeV scale, hidden U(1) forces with nonzero axial-vector couplings to Standard Model fermions. While the purely vector-coupled dark photon, which may arise from kinetic mixing, is a well-motivated scenario, several MeV-scale anomalies motivate a theory with axial couplings which can be UV-completed consistent with Standard Model gauge invariance. Moreover, existing constraints on dark photons depend on products of various combinations of axial and vector couplings, making it difficult to isolate the effects of axial couplings for particular flavors of SM fermions. We present a representative renormalizable, UV-complete model of a dark photon with adjustable axial and vector couplings, discuss its general features, and show how some UV constraints may be relaxed in a model with nonrenormalizable Yukawa couplings at the expense of fine-tuning. We survey the existing parameter space and the projected reach of planned experiments, briefly commenting on the relevan...
Light Weakly Coupled Axial Forces: Models, Constraints, and Projections
Kahn, Yonatan [Princeton U.; Krnjaic, Gordan [Fermilab; Mishra-Sharma, Siddharth [Princeton U.; Tait, Tim P. [UC, Irvine
2016-09-28
We investigate the landscape of constraints on MeV-GeV scale, hidden U(1) forces with nonzero axial-vector couplings to Standard Model fermions. While the purely vector-coupled dark photon, which may arise from kinetic mixing, is a well-motivated scenario, several MeV-scale anomalies motivate a theory with axial couplings which can be UV-completed consistent with Standard Model gauge invariance. Moreover, existing constraints on dark photons depend on products of various combinations of axial and vector couplings, making it difficult to isolate the effects of axial couplings for particular flavors of SM fermions. We present a representative renormalizable, UV-complete model of a dark photon with adjustable axial and vector couplings, discuss its general features, and show how some UV constraints may be relaxed in a model with nonrenormalizable Yukawa couplings at the expense of fine-tuning. We survey the existing parameter space and the projected reach of planned experiments, briefly commenting on the relevance of the allowed parameter space to low-energy anomalies in pi^0 and 8-Be* decay.
Amphiregulin Antibody and Reduction of Axial Elongation in Experimental Myopia
Wen Jun Jiang
2017-03-01
Full Text Available To examine the mechanism of ocular axial elongation in myopia, guinea pigs (age: 2–3 weeks which either underwent unilateral or bilateral lens-induced myopization (group 1 or which were primarily myopic at baseline (group 2 received unilateral intraocular injections of amphiregulin antibody (doses: 5, 10, or 15 μg three times in intervals of 9 days. A third group of emmetropic guinea pigs got intraocular unilateral injections of amphiregulin (doses: 0.25, 0.50 or 1.00 ng, respectively. In each group, the contralateral eyes received intraocular injections of Ringer's solution. In intra-animal inter-eye comparison and intra-eye follow-up comparison in groups 1 and 2, the study eyes as compared to the contralateral eyes showed a dose-dependent reduction in axial elongation. In group 3, study eyes and control eyes did not differ significantly in axial elongation. Immunohistochemistry revealed amphiregulin labelling at the retinal pigment epithelium in eyes with lens-induced myopization and Ringer's solution injection, but not in eyes with amphiregulin antibody injection. Intraocular injections of amphiregulin-antibody led to a reduction of lens-induced axial myopic elongation and of the physiological eye enlargement in young guinea pigs. In contrast, intraocularly injected amphiregulin in a dose of ≤1 ng did not show a significant effect. Amphiregulin may be one of several essential molecular factors for axial elongation.
Axial clamp for nuclear reactor head penetration conoseal joints
Hackley, T.A.
1987-03-31
A method is described for forming a sealed coupling between two bodies, each body presenting an annular abutment surface. The respective bodies are arranged so that their respective annular abutment surfaces are axially adjacent one another, defining a space therebetween, wherein a deformable gasket is disposed within the space. The method comprises: providing one of the bodies with an annular projection; providing the other body with threads for receiving an annular locknut which can be tightened to bear against the annular projection of the one body; applying an external axial forced to the bodies for compressing the abutment surfaces together against the gasket to form a seal between the bodies; immobilizing the bodies relative to one another while the external force is being applied to the bodies by hand-tightening an annular locknut via the threads of the other body until the locknut abuts the annular projection of the one body, substantially preventing relative axial movement between the bodies when the external axial force is withdrawn; and withdrawing the external axial force applied to the bodies, leaving the two bodies coupled together via the seal.
An Axial-Vector Photon in a Mirror World
Sharafiddinov, Rasulkhozha S.
2016-03-01
The unity of symmetry laws emphasizes, in the case of a mirror CP-even Dirac Lagrangian, the ideas of the left- and right-handed axial-vector photons referring to long- and short-lived bosons of true neutrality, respectively. Such a difference in lifetimes expresses the unidenticality of masses, energies and momenta of axial-vector photons of the different components. They define the unified field theory equation of C-odd particles with an integral spin. Together with a new equation of a theory of truly neutral particles with the half-integral spin, the latter reflects the availability in their nature of the second type of the local axial-vector gauge transformation responsible for origination in the Lagrangian of C-oddity of an interaction Newton component giving an axial-vector mass to all the interacting particles and fields. The mirror axial-vector mass, energy and momentum operators constitute a CP-invariant equation of quantum mechanics, confirming that each of them can individually influence on matter field. Thereby, findings suggest at the level of the mass-charge structure of gauge invariance a new equation for the C-noninvariant Lagrangian.
Yu, Xinxin; Lin, Ting; Lv, Huafei; Pan, Sujuan; Wu, Shijun; Zeng, Di; Jiang, Yufeng; Wang, Yuhua; Yang, Hongqin; Huang, Yide; Peng, Yiru
2016-10-01
Metal phthalocyanines (MPcs) have been found to be a promising photosensitizers for photodynamic therapy (PDT) of cancers and non-cancer diseases. Nevertheless, phthalocyanines are substantially limited in clinical applications owing to their poor solubility, aggregation and insufficient selectivity for cancer cells. Catechol is an important pharmaceutical intermediate, playing important in vivo biological activity in medicine. Using catechol (pyrocatechin) as axial ligands, utilizing of the pharmaceutical effect of catechins, could improve the bioavailability, and achieve synergistic therapeutic effect in PDT. To address these issues, a novel catechol axially substituted tetra-α-(pentyloxy) titanium(IV) (TiPc(OC5H11)4-Catechol) was synthesized. The structure of TiPc(OC5H11)4-Catechol was characterized by elemental analysis, IR, 1HNMR and MS methods. The photophysical properties of TiPc(OC5H11)4 and TiPc(OC5H11)4-Catechol have been studied by UV/Vis and steady-state fluorescence spectra. After being axially substituted with catechin groups, no obviously intensity and position of maximum wavelength in Q-band of TiPc(OC5H11)4 and TiPc(OC5H11)4-Catechol were observed. The fluorescence intensity of TiPc(OC5H11)4 was stronger than that of TiPc(OC5H11)4-Catechol, but the fluorescence lifetime of TiPc(OC5H11)4-Catechol was longer than that of TiPc(OC5H11)4. TiPc(OC5H11)4-Catechol may be considered as a promising photosensitizer for PDT.
Dimensions of the human sclera: Thickness measurement and regional changes with axial length.
Norman, Richard E; Flanagan, John G; Rausch, Sophie M K; Sigal, Ian A; Tertinegg, Inka; Eilaghi, Armin; Portnoy, Sharon; Sled, John G; Ethier, C Ross
2010-02-01
Scleral thickness, especially near the region of the optic nerve head (ONH), is a potential factor of interest in the development of glaucomatous optic neuropathy. Our goal was to characterize the scleral thickness distribution and other geometric features of human eyes. Eleven enucleated human globes (7 normal and 4 ostensibly glaucomatous) were imaged using high-field microMRI, providing 80 microm isotropic resolution over the whole eye. The MRI scans were segmented to produce 3-D corneoscleral shells. Each shell was divided into 15 slices along the anterior-posterior axis of the eye, and each slice was further subdivided into the anatomical quadrants. Average thickness was measured in each region, producing 60 thickness measurements per eye. Hierarchical clustering was used to identify trends in the thickness distribution, and scleral geometric features were correlated with globe axial length. Thickness over the whole sclera was 670 +/- 80 microm (mean +/- SD; range: 564 microm-832 microm) over the 11 eyes. Maximum thickness occurred at the posterior pole of the eye, with mean thickness of 996 +/- 181 microm. Thickness decreased to a minimum at the equator, where a mean thickness of 491 +/- 91 microm was measured. Eyes with a reported history of glaucoma were found to have longer axial length, smaller ONH canal dimensions and thinner posterior sclera. Several geometrical parameters of the eye, including posterior scleral thickness, axial length, and ONH canal diameter, appear linked. Significant intra-individual and inter-individual variation in scleral thickness was evident. This may be indicative of inter-individual differences in ocular biomechanics. Copyright 2009 Elsevier Ltd. All rights reserved.
Huang, Jinxin; Yuan, Qun; Tankam, Patrice; Clarkson, Eric; Kupinski, Matthew; Hindman, Holly B.; Aquavella, James V.; Rolland, Jannick P.
2015-03-01
In biophotonics imaging, one important and quantitative task is layer-thickness estimation. In this study, we investigate the approach of combining optical coherence tomography and a maximum-likelihood (ML) estimator for layer thickness estimation in the context of tear film imaging. The motivation of this study is to extend our understanding of tear film dynamics, which is the prerequisite to advance the management of Dry Eye Disease, through the simultaneous estimation of the thickness of the tear film lipid and aqueous layers. The estimator takes into account the different statistical processes associated with the imaging chain. We theoretically investigated the impact of key system parameters, such as the axial point spread functions (PSF) and various sources of noise on measurement uncertainty. Simulations show that an OCT system with a 1 μm axial PSF (FWHM) allows unbiased estimates down to nanometers with nanometer precision. In implementation, we built a customized Fourier domain OCT system that operates in the 600 to 1000 nm spectral window and achieves 0.93 micron axial PSF in corneal epithelium. We then validated the theoretical framework with physical phantoms made of custom optical coatings, with layer thicknesses from tens of nanometers to microns. Results demonstrate unbiased nanometer-class thickness estimates in three different physical phantoms.
Rautenberg, M., E-mail: mrautenb@gmail.com [AREVA, AREVA NP, 10 rue Juliette Récamier, 69456 Lyon (France); CIRIMAT, CNRS/UPS/INPT, 4 allée Emile Monso, 31030 Toulouse (France); Poquillon, D. [CIRIMAT, CNRS/UPS/INPT, 4 allée Emile Monso, 31030 Toulouse (France); Pilvin, P. [LIMATB, University Bretagne-Sud, rue de Saint-Maudé, 56321 Lorient (France); Grosjean, C. [AREVA, AREVA NP, 10 rue Juliette Récamier, 69456 Lyon (France); CIRIMAT, CNRS/UPS/INPT, 4 allée Emile Monso, 31030 Toulouse (France); Cloué, J.M. [AREVA, AREVA NP, 10 rue Juliette Récamier, 69456 Lyon (France); Feaugas, X. [LEMMA, Université de La Rochelle, Avenue Michel Crépeau, 17042 La Rochelle (France)
2014-04-01
Zirconium alloys are widely used in the nuclear industry. Several components, such as cladding or guide tubes, undergo strong mechanical loading during and after their use inside the pressurized water reactors. The current requirements on higher fuel performances lead to the developing on new Zr based alloys exhibiting better mechanical properties. In this framework, creep behaviors of recrystallized Zircaloy-4 and M5™, have been investigated and then compared. In order to give a better understanding of the thermal creep anisotropy of Zr-based alloys, multi-axial creep tests have been carried out at 673 K. Using a specific device, creep conditions have been set using different values of β = σ{sub zz}/σ{sub θθ}, σ{sub zz} and σ{sub θθ} being respectively the axial and hoop creep stresses. Both axial and hoop strains are measured during each test which is carried out until stationary creep is stabilized. The steady-state strain rates are then used to build isocreep curves. Considering the isocreep curves, the M5™ alloy shows a largely improved creep resistance compared to the recrystallized Zircaloy-4, especially for tubes under high hoop loadings (0 < β < 1). The isocreep curves are then compared with simulations performed using two different mechanical models. Model 1 uses a von Mises yield criterion, the model 2 is based on a Hill yield criterion. For both models, a coefficient derived from Norton law is used to assess the stress dependence.
Stress analysis in platform-switching implants: a 3-dimensional finite element study.
Pellizzer, Eduardo Piza; Verri, Fellippo Ramos; Falcón-Antenucci, Rosse Mary; Júnior, Joel Ferreira Santiago; de Carvalho, Paulo Sérgio Perri; de Moraes, Sandra Lúcia Dantas; Noritomi, Pedro Yoshito
2012-10-01
The aim of this study was to evaluate the influence of the platform-switching technique on stress distribution in implant, abutment, and peri-implant tissues, through a 3-dimensional finite element study. Three 3-dimensional mandibular models were fabricated using the SolidWorks 2006 and InVesalius software. Each model was composed of a bone block with one implant 10 mm long and of different diameters (3.75 and 5.00 mm). The UCLA abutments also ranged in diameter from 5.00 mm to 4.1 mm. After obtaining the geometries, the models were transferred to the software FEMAP 10.0 for pre- and postprocessing of finite elements to generate the mesh, loading, and boundary conditions. A total load of 200 N was applied in axial (0°), oblique (45°), and lateral (90°) directions. The models were solved by the software NeiNastran 9.0 and transferred to the software FEMAP 10.0 to obtain the results that were visualized through von Mises and maximum principal stress maps. Model A (implants with 3.75 mm/abutment with 4.1 mm) exhibited the highest area of stress concentration with all loadings (axial, oblique, and lateral) for the implant and the abutment. All models presented the stress areas at the abutment level and at the implant/abutment interface. Models B (implant with 5.0 mm/abutment with 5.0 mm) and C (implant with 5.0 mm/abutment with 4.1 mm) presented minor areas of stress concentration and similar distribution pattern. For the cortical bone, low stress concentration was observed in the peri-implant region for models B and C in comparison to model A. The trabecular bone exhibited low stress that was well distributed in models B and C. Model A presented the highest stress concentration. Model B exhibited better stress distribution. There was no significant difference between the large-diameter implants (models B and C).
A dual method for maximum entropy restoration
Smith, C. B.
1979-01-01
A simple iterative dual algorithm for maximum entropy image restoration is presented. The dual algorithm involves fewer parameters than conventional minimization in the image space. Minicomputer test results for Fourier synthesis with inadequate phantom data are given.
Maximum Throughput in Multiple-Antenna Systems
Zamani, Mahdi
2012-01-01
The point-to-point multiple-antenna channel is investigated in uncorrelated block fading environment with Rayleigh distribution. The maximum throughput and maximum expected-rate of this channel are derived under the assumption that the transmitter is oblivious to the channel state information (CSI), however, the receiver has perfect CSI. First, we prove that in multiple-input single-output (MISO) channels, the optimum transmission strategy maximizing the throughput is to use all available antennas and perform equal power allocation with uncorrelated signals. Furthermore, to increase the expected-rate, multi-layer coding is applied. Analogously, we establish that sending uncorrelated signals and performing equal power allocation across all available antennas at each layer is optimum. A closed form expression for the maximum continuous-layer expected-rate of MISO channels is also obtained. Moreover, we investigate multiple-input multiple-output (MIMO) channels, and formulate the maximum throughput in the asympt...
Photoemission spectromicroscopy with MAXIMUM at Wisconsin
Ng, W.; Ray-Chaudhuri, A.K.; Cole, R.K.; Wallace, J.; Crossley, S.; Crossley, D.; Chen, G.; Green, M.; Guo, J.; Hansen, R.W.C.; Cerrina, F.; Margaritondo, G. (Dept. of Electrical Engineering, Dept. of Physics and Synchrotron Radiation Center, Univ. of Wisconsin, Madison (USA)); Underwood, J.H.; Korthright, J.; Perera, R.C.C. (Center for X-ray Optics, Accelerator and Fusion Research Div., Lawrence Berkeley Lab., CA (USA))
1990-06-01
We describe the development of the scanning photoemission spectromicroscope MAXIMUM at the Wisoncsin Synchrotron Radiation Center, which uses radiation from a 30-period undulator. The article includes a discussion of the first tests after the initial commissioning. (orig.).
Maximum-likelihood method in quantum estimation
Paris, M G A; Sacchi, M F
2001-01-01
The maximum-likelihood method for quantum estimation is reviewed and applied to the reconstruction of density matrix of spin and radiation as well as to the determination of several parameters of interest in quantum optics.
The maximum entropy technique. System's statistical description
Belashev, B Z
2002-01-01
The maximum entropy technique (MENT) is applied for searching the distribution functions of physical values. MENT takes into consideration the demand of maximum entropy, the characteristics of the system and the connection conditions, naturally. It is allowed to apply MENT for statistical description of closed and open systems. The examples in which MENT had been used for the description of the equilibrium and nonequilibrium states and the states far from the thermodynamical equilibrium are considered
19 CFR 114.23 - Maximum period.
2010-04-01
... 19 Customs Duties 1 2010-04-01 2010-04-01 false Maximum period. 114.23 Section 114.23 Customs... CARNETS Processing of Carnets § 114.23 Maximum period. (a) A.T.A. carnet. No A.T.A. carnet with a period of validity exceeding 1 year from date of issue shall be accepted. This period of validity cannot be...
Maximum-Likelihood Detection Of Noncoherent CPM
Divsalar, Dariush; Simon, Marvin K.
1993-01-01
Simplified detectors proposed for use in maximum-likelihood-sequence detection of symbols in alphabet of size M transmitted by uncoded, full-response continuous phase modulation over radio channel with additive white Gaussian noise. Structures of receivers derived from particular interpretation of maximum-likelihood metrics. Receivers include front ends, structures of which depends only on M, analogous to those in receivers of coherent CPM. Parts of receivers following front ends have structures, complexity of which would depend on N.
Healthy Lifestyle Stress management Job stress can be all-consuming — but it doesn't have to be. Address your triggers, keep perspective and ... stress triggers, it's often helpful to improve time management skills — especially if you tend to feel overwhelmed ...
Dynamic Behavior of Axially Functionally Graded Pipes Conveying Fluid
Chen An
2017-01-01
Full Text Available Dynamic behavior of axially functionally graded (FG pipes conveying fluid was investigated numerically by using the generalized integral transform technique (GITT. The transverse vibration equation was integral transformed into a coupled system of second-order differential equations in the temporal variable. The Mathematica’s built-in function, NDSolve, was employed to numerically solve the resulting transformed ODE system. Excellent convergence of the proposed eigenfunction expansions was demonstrated for calculating the transverse displacement at various points of axially FG pipes conveying fluid. The proposed approach was verified by comparing the obtained results with the available solutions reported in the literature. Moreover, parametric studies were performed to analyze the effects of Young’s modulus variation, material distribution, and flow velocity on the dynamic behavior of axially FG pipes conveying fluid.
Bistability between equatorial and axial dipoles during magnetic field reversals
Gissinger, Christophe; Schrinner, Martin; Dormy, Emmanuel
2012-01-01
Numerical simulations of the geodynamo in presence of an heterogeneous heating are presented. We study the dynamics and the structure of the magnetic field when the equatorial symmetry of the flow is broken. If the symmetry breaking is sufficiently strong, the m = 0 axial dipolar field is replaced by an hemispherical magnetic field, dominated by an oscillating m = 1 magnetic field. Moreover, for moderate symmetry breaking, a bistability between the axial and the equatorial dipole is observed. In this bistable regime, the axial magnetic field exhibits chaotic switches of its polarity, involving the equatorial dipole during the transition period. This new scenario for magnetic field reversals is discussed within the framework of the Earth's dynamo.
Bistability between equatorial and axial dipoles during magnetic field reversals.
Gissinger, Christophe; Petitdemange, Ludovic; Schrinner, Martin; Dormy, Emmanuel
2012-06-08
Numerical simulations of the geodynamo in the presence of heterogeneous heating are presented. We study the dynamics and the structure of the magnetic field when the equatorial symmetry of the flow is broken. If the symmetry breaking is sufficiently strong, the m=0 axial dipolar field is replaced by a hemispherical magnetic field, dominated by an oscillating m=1 magnetic field. Moreover, for moderate symmetry breaking, a bistability between the axial and the equatorial dipole is observed. In this bistable regime, the axial magnetic field exhibits chaotic switches of its polarity, involving the equatorial dipole during the transition period. This new scenario for magnetic field reversals is discussed within the framework of Earth's dynamo.
Numerical analysis of cavitation within slanted axial-flow pump
张睿; 陈红勋
2013-01-01
In this paper, the cavitating flow within a slanted axial-flow pump is numerically researched. The hydraulic and cavitation performance of the slanted axial-flow pump under different operation conditions are estimated. Compared with the experimental hydraulic performance curves, the numerical results show that the filter-based model is better than the standard k-e model to predict the parameters of hydraulic performance. In cavitation simulation, compared with the experimental results, the proposed numerical method has good predicting ability. Under different cavitation conditions, the internal cavitating flow fields within slanted axial-flow pump are investigated. Compared with flow visualization results, the major internal flow features can be effectively grasped. In order to explore the origin of the cavitation performance breakdown, the Boundary Vorticity Flux (BVF) is introduced to diagnose the cavitating flow fields. The analysis results indicate that the cavitation performance drop is relevant to the instability of cavitating flow on the blade suction surface.
Unsteady cooperative flow type in the axial compressor
ZHENG Xinqian; ZHOU Sheng; HOU Anping; XIONG Jinsong
2005-01-01
For increasing the performance of the axial compressor, a method for realizing unsteady cooperative flow type is proposed in this paper as a critical objective in the new generation of the axial compressor design system. Unsteady excitations were utilized to trigger the transformation from the unsteady natural flow pattern into the unsteady cooperative flow pattern, resulting in increment of aerodynamic performances of axial compressor. Numerical simulations show that distinct positive effect can be obtained for the 2D cascade in a wide range of subsonic working conditions. No positive effect can be observed under the 2D supersonic working conditions and unsteady excitations have little influence on the flow field space-time structure. However, positive effect can be obtained under the 3D transsonic working conditions. In addition, engineering applications of unsteady cooperative flow type are discussed.
Ball Screw Actuator Including an Axial Soft Stop
Wingett, Paul T. (Inventor); Forrest, Steven Talbert (Inventor); Abel, Steve (Inventor); Woessner, George (Inventor); Hanlon, Casey (Inventor)
2016-01-01
An actuator includes an actuator housing, a ball screw, and an axial soft stop assembly. The ball screw extends through the actuator housing and has a first end and a second end. The ball screw is coupled to receive a drive force and is configured, upon receipt of the drive force, to selectively move in a retract direction and an extend direction. The axial soft stop assembly is disposed within the actuator housing. The axial soft stop assembly is configured to be selectively engaged by the ball screw and, upon being engaged thereby, to translate, with compliance, a predetermined distance in the extend direction, and to prevent further movement of the ball screw upon translating the predetermined distance.
Liquid Axial Mixing in Packed Tower at Elevated Pressure
唐忠利; 张鹏; 等
2003-01-01
Liquid phase axial mixing was measured with the tracer technique in a packed column with inner diameter of 0.15m,in which the structured packing,Mellapak 350Y,was installed.Tap water as the liquid phase flowed down through the column and stagnant gas was at elevated pressure ranging from atmospheric to 2.0MPa.The model parameters of Bo andθwere estimated with the least square method in the time domain.As liquid flow rate was increased,the liquid axial mixing decreased.under our experimental conditions,the effect of pressure on Bo number on single liquid phase was negligible,and eddy diffusion was believed to be the primary cause of axial mixing in liquid phase.
Yamazaki, K; Umezu, M; Koyanagi, H; Kitamura, M; Eishi, K; Kawai, A; Tagusari, O; Niinami, H; Akimoto, T; Nojiri, C
1992-01-01
A new intraventricular axial flow blood pump has been designed and developed as an implantable left ventricular assist device (LVAD). The pump consists of a tube housing (10 cm in length and 14 mm in diameter), a three-vane impeller combined with a guide vane, and a DC motor. This pump is introduced into the LV cavity through the LV apex, and the outlet cannula is passed antegrade across the aortic valve. Blood is withdrawn from the LV through the inlet ports at the pump base, and discharged into the ascending aorta. A pump flow of > 8 L/min was obtained against 90 mmHg differential pressure in the mock circulatory system. In an acute dog model, this pump could produce a sufficient output of 200 ml/kg/min. In addition, the pump flow profile demonstrated a pulsatile pattern, although the rotation speed was fixed. This is mainly due to the changes in flow rate during a cardiac cycle--that is, during systole, the flow rate increases to the maximum, while the differential pressure between the LV and the aorta decreases to the minimum. Thus, this simple and compact axial flow blood pump can be a potential LVAD, with prompt accessibility and need for less invasive surgical procedures.
Energy absorption of aluminum alloy thin-walled tubes under axial impact
Sun, Hongtu; Wang, Jian [Ludong University, Yantai (China); Shen, Guozhe; Hu, Ping [Dalian University of Technology, Dalian (China)
2016-07-15
Aluminum alloys are important technological materials for achieving the lightweight design of automotive structures. Many works have reported on the deformation and energy absorption of thin-walled tubes. Multicorner tubes with extra concave corners in the cross section were presented in this study to improve the energy absorption efficiency of aluminum alloy thin-walled tubes. The axial crushing of square and multicorner thin-walled tubes was simulated with the same cross-sectional perimeter. The method of folding element was applied to predict the crushing behavior of the thin-walled tubes under axial impact. The corners on the cross section were discussed to determine their effect on the energy absorption performance of thin-walled tubes. Results showed that the increasing performance of energy absorption of aluminum alloy thin-walled tubes was caused by the increasing number of corners on the cross section of multicorner tubes. Both the number and size of corners had an important effect on the crushing force efficiency of multicorner tubes. The maximum crushing force efficiency of multicorner tubes was 11.6% higher than that of square tubes with the same material consumption of thin-walled tubes. The multicorner tubes with 12 corners showed better energy absorption performance than the tubes with more than 12 corners; this high number of corners could lead to the small size of corners or unstable deformations. The high energy absorption performance of multicorner tubes prefers increasing the corner number and corner size of adjacent sides at the same time.
Li, Zhang; Jin, Yingzi; Huashu, Dou; Yuzhen, Jin
2013-10-01
To reduce the influence of adverse flow conditions at the fan hub and improve fan aerodynamic performance, a modification of conventional axial fan blades with numerical and experimental investigation is presented. Hollow blade root is manufactured near the hub. The numerical and experimental results show that hollow blade root has some effect on the static performance. Static pressure of the modified fan is generally the same with that of the datum fan, while, the efficiency curve of the modified fan has a different trend with that of the datum fan. The highest efficiency of the modified fan is 10% greater than that of the datum fan. The orthogonal experimental results of fan noise show that hollow blade root is a feasible method of reducing fan noise, and the maximum value of noise reduction is about 2 dB. The factors affecting the noise reduction of hollow blade root are in the order of importance as follows: hollow blade margin, hollow blade height and hollow blade width. The much smoother pressure distribution of the modified fan than that of the datum fan is the main mechanism of noise reduction of hollow blade root. The research results will provide the proof of the parameter optimization and the structure design for high performance and low noise small axial fans.
Low-pressure reversible axial fan with straight profile blades and relatively high efficiency
Spasić Živan T.
2012-01-01
Full Text Available The paper presents the design and operating characteristics of a model of reversible axial fan with only one impeller, whose reversibility is achieved by changing the direction of rotation. The fan is designed for the purpose of providing alternating air circulation in wood dryers in order to reduce the consumption of electricity for the fan and increase energy efficiency of the entire dryer. To satisfy the reversibility of flow, the shape of the blade profile is symmetrical along the longitudinal and transversal axes of the profile. The fan is designed with equal specific work of all elementary stages, using the method of lift forces. The impeller blades have straight mean line profiles. The shape of the blade profile was adopted after the numerical simulations were carried out and high efficiency was achieved. Based on the calculation and conducted numerical simulations, a physical model of the fan was created and tested on a standard test rig, with air loading at the suction side of the fan. The operating characteristics are shown for different blade angles. The obtained maximum efficiency was around 0.65, which represents a rather high value for axial fans with straight profile blades.
SEXUAL DIMORPHISM OF MAXIMUM FEMORAL LENGTH
Pandya A M
2011-04-01
Full Text Available Sexual identification from the skeletal parts has medico legal and anthropological importance. Present study aims to obtain values of maximum femoral length and to evaluate its possible usefulness in determining correct sexual identification. Study sample consisted of 184 dry, normal, adult, human femora (136 male & 48 female from skeletal collections of Anatomy department, M. P. Shah Medical College, Jamnagar, Gujarat. Maximum length of femur was considered as maximum vertical distance between upper end of head of femur and the lowest point on femoral condyle, measured with the osteometric board. Mean Values obtained were, 451.81 and 417.48 for right male and female, and 453.35 and 420.44 for left male and female respectively. Higher value in male was statistically highly significant (P< 0.001 on both sides. Demarking point (D.P. analysis of the data showed that right femora with maximum length more than 476.70 were definitely male and less than 379.99 were definitely female; while for left bones, femora with maximum length more than 484.49 were definitely male and less than 385.73 were definitely female. Maximum length identified 13.43% of right male femora, 4.35% of right female femora, 7.25% of left male femora and 8% of left female femora. [National J of Med Res 2011; 1(2.000: 67-70
Regional brain axial and radial diffusivity changes during development.
Kumar, Rajesh; Nguyen, Haidang D; Macey, Paul M; Woo, Mary A; Harper, Ronald M
2012-02-01
The developing human brain shows rapid myelination and axonal changes during childhood, adolescence, and early adulthood, requiring successive evaluations to determine normative values for potential pathological assessment. Fiber characteristics can be examined by axial and radial diffusivity procedures, which measure water diffusion parallel and perpendicular to axons and show primarily axonal status and myelin changes, respectively. Such measures are lacking from widespread sites for the developing brain. Diffusion tensor imaging data were acquired from 30 healthy subjects (age 17.7 ± 4.6 years, range 8-24 years, body mass index 21.5 ± 4.5 kg/m(2), 18 males) using a 3.0-Tesla MRI scanner. Diffusion tensors were calculated, principal eigenvalues determined, and axial and radial diffusivity maps calculated and normalized to a common space. A set of regions of interest was outlined from widespread brain areas within rostral, thalamic, hypothalamic, cerebellar, and pontine regions, and average diffusivity values were calculated using normalized diffusivity maps and these regions of interest masks. Age-related changes were assessed with Pearson's correlations, and gender differences evaluated with Student's t-tests. Axial and radial diffusivity values declined with age in the majority of brain areas, except for midhippocampus, where axial diffusivity values correlated positively with age. Gender differences emerged within putamen, thalamic, hypothalamic, cerebellar, limbic, temporal, and other cortical sites. Documentation of normal axial and radial diffusivity values will help assess disease-related tissue changes. Axial and radial diffusivities change with age,with fiber structure and organization differing between sexes in several brain areas. The findings may underlie gender-based functional characteristics, and mandate partitioning age- and gender-related changes during developmental brain pathology evaluation.
Gharib-Zahedi, Mohammad Reza; Tafazzoli, Mohsen; Böhm, Michael C.; Alaghemandi, Mohammad
2013-11-01
Using reverse nonequilibrium molecular dynamics simulations the influence of intermolecular bridges on the thermal conductivity (λ) in carbon nanotube (CNT) bundles has been investigated. The chosen cross linkers (CH2, O, CO) strengthen the transversal energy transport relative to the one in CNT bundles without bridges. The results showed that λ does not increase linearly with the linker density. The efficiency of the heat transport is determined by the number of linkers in the direction of the heat flux, the type of the linker, and their spatial ordering. The influence of a forced axial stress on the transversal λ has been also studied. The observed λ reduction with increasing axial stretching in a neat CNT bundle can be (over)compensated by cross linkers. The present computational data emphasize the contribution of phonons to the transversal heat transport in CNT bundles with intertube bonds.
Vector and Axial Currents in Wilson Chiral Perturbation Theory
Aoki, Sinya; Sharpe, Stephen R
2009-01-01
We reconsider the construction of the vector and axial-vector currents in Wilson Chiral Perturbation Theory (WChPT), the low-energy effective theory for lattice QCD with Wilson fermions. We discuss in detail the finite renormalization of the currents that has to be taken into account in order to properly match the currents. We explicitly show that imposing the chiral Ward identities on the currents does, in general, affect the axial-vector current at O(a). As an application of our results we compute the pion decay constant to one loop in the two flavor theory. Our result differs from previously published ones.
Self-collimated axial jets from thin accretion disks
Tirabassi, Giulio; Carlevaro, Nakia; Benini, Riccardo
2012-01-01
We show how an appropriate stationary crystalline structure of the magnetic field can induce a partial fragmentation of the accretion disk, generating an axial jet composed of hot rising plasma twisted in a funnel-like structure by the rotation of the system. The most important feature of the obtained jet is its high degree of collimation, naturally arising from the condition for its existence. The presence of non-zero dissipative effects allows the plasma ejection throughout the axial jet and the predicted values of the accretion rate are in agreement with observations.
Spectral analysis in thin tubes with axial heterogeneities
Ferreira, Rita
2015-01-01
In this paper, we present the 3D-1D asymptotic analysis of the Dirichlet spectral problem associated with an elliptic operator with axial periodic heterogeneities. We extend to the 3D-1D case previous 3D-2D results (see [10]) and we analyze the special case where the scale of thickness is much smaller than the scale of the heterogeneities and the planar coefficient has a unique global minimum in the periodic cell. These results are of great relevance in the comprehension of the wave propagation in nanowires showing axial heterogeneities (see [17]).
An effective theory for QCD with an axial chemical potential
Andrianov, Alexander A; Espriu, Domenec; Planells, Xumeu
2013-01-01
We consider the low energy realization of QCD in terms of meson fields when an axial chemical potential is present; a situation that may be relevant in heavy ion collisions. We shall demonstrate that the presence of an axial charge constitutes an explicit source of parity breaking. The eigenstates of strong interactions do not have a definite parity and interactions that would otherwise be forbidden compete with the familiar ones. In this work, we first focus on scalars and pseudoscalars that are described by a generalized linear sigma model; and next, we give some hints on how the Vector Meson Dominance model describes the vector sector.
Fermion decoupling and the axial anomaly on the lattice
Banerjee, H; De, Asit K.
1999-01-01
By an explicit calculation of the continuum limit of the triangle graph amplitude in lattice QED we show that in the axial Ward identity the ABJ anomaly exactly cancels the pseudoscalar density term in the limit of infinite fermion mass $m$. The result, a reflection of decoupling of the heavy fermion, provides a convenient framework for computing the flavor-singlet or U(1) axial anomaly in non-Abelian gauge theories on lattice. Our calculations on the lattice are performed using Wilson fermions but the results are general.
The axial topographic high at intermediate and fast spreading ridges
Carbotte, Suzanne M.; MacDonald, Ken C.
1994-12-01
An axial topographic high is commonly observed at both fast spreading ridges and some segments of intermediate spreading ridges. At fast rates the axial high is primarily created by the buoyancy of hot rock and magma beneath the rise. As newly formed crust is transported off axis, little vestige of an axial high is observed on the ridge flanks. In contrast, at intermediate rates, a significant component of the positive topography may be a volcanic construction, preserved on the ridge flanks as abyssal hills, which are slit axial volcanoes. We suggest this difference in the nature of the axial high reflects a lithosphere strong enough to support construction of a volcanic crestal ridge at intermediate spreading rates, but only rarely at fast rates. Relict overlap ridges, found within the discordant zones left by overlapping spreading centers, is one class of ridge-flank topography which appears to have a significant volcanic constructional component even at fast spreading ridges. Unlike topography away from these discontinuities, the relief and shape of overlapping spreading centers is preserved as relict ridge tips are rafted onto the ridge flanks. Reduced magma supply at these discontinuities may give rise to an axial lithosphere strong enough to support volcanic construction of overlap ridges. Low axial lithospheric strength may also account for the lack of normal faults within the innermost 1-2 km of fast, and some intermediate, spreading ridges. With a thin/weak brittle layer at the ridge crest, tensile failure will predominate and few normal faults will form. Depths to the axial magma chamber reflector observed in multi-channel seismic data limit the thickness of the brittel layer on axis to less than 1-2 km for much of the East Pacific Rise (EPR). This depth is comparable to depths over which tensile failure within the oceanic crust will predominate, estimated from the Griffith criteria for fracture initiation (approx. 0.5-1.5 km). As the brittle layer
Recent Results on High-Pressure Axial Blowers
Eckert, B.
1947-01-01
Considerable progress has, in recent times, been attained in the development of the high-pressure axial blower by well-planned research. The efforts are directed toward improving the efficiencies, which are already high for the axial blower, and in particular the delivery pressure heads. For high pressures multistage arrangements are used. Of fundamental importance is the careful design of all structural parts of the blower that are subject to the effects of the flow. In the present report, several recent results and experiences are reported, which are based on results of German engine research.
The seismic design of axial blower using Ansys
Im, Hyung Bin; Kim, Kang Sung; Heo, Jin Wook; Chung, Jin Tai [Hanyang Univ., Seoul (Korea, Republic of)
2001-07-01
The seismic design for an axial blower is the procedure in which the Required Response Spectrum(RRS) is computed by using the Floor Response Spectrum(FRS). The seismic design is very important to reduce severe damages from an earthquake; therefore, the seismic design has been a great concern in engineering society. In this study, after finite element modeling is established by using Ansys, the modal data are obtained such as the natural frequencies, the participation factor, and so on. With these data, the RRS is acquired by a numerical approach. The seismic safety of the axial blower is evaluated.
Numerical simulation of stress distribution in Al2 O3-TiC/Q235 diffusion bonded joints
无
2008-01-01
The distributions of the axial stress and shear stress in Al2O3-TiC/Q235 diffusion bonded joints were studied using finite element method (FEM). The effect of interlayer thickness on the axial stress and shear stress was also investigated. The results indicate that the gradients of the axial stress and shear stress are great near the joint edge. The maximal shear stress produces at the interface of the Al2O3-TiC and Ti interlayer. With the increase of Cu interlayer thickness, the magnitudes of the axial stress and shear stress first decrease and then increase. The distribution of the axial stress changes greatly with a little change in the shear stress. The shear fracture initiates at the interface of the Al2O3-TiC/ Ti interlayer with high shear stress and then propagates to the Al2O3-TiC side, which is consistent with the stress FEM calculating results.
... Kids to Be Smart About Social Media Childhood Stress KidsHealth > For Parents > Childhood Stress Print A A ... and feel stress to some degree. Sources of Stress Stress is a function of the demands placed ...
Pham, M. S.; Creuziger, A.; Iadicola, M.; Rollett, A. D.
2017-02-01
This study investigates the joint impact of preferred texture and latent hardening on the plastic anisotropy of face centered cubic (FCC) materials. The main result is that both aspects have significant impact on the anisotropy, but the two can either counteract each other or synergistically reinforce each other to maximize anisotropy. Preferred texture results in significant anisotropy in plastic yielding. However, the latent hardening significantly alters the texture-induced anisotropy. In addition, one latent hardening type can cancel out the anisotropy of another type. Consequently, if all dislocation-based latent hardening types are included at the same level as the self-hardening, the result might not reveal the complexity of plastic anisotropy. The present study of the synergistic influence of detailed latent hardening and texture presented helps provide new insights into the complex anisotropic behavior of FCC materials during multi-axial forming. the stress at which the material initially yields is not a function of material orientation with respect to the frame of the test (i.e., isotropic yielding); there exists a multi-axial yield locus that is described by a single value of stress that corresponds to yield in uniaxial tension (i.e., stress equivalency); on hardening, the multi-axial yield locus expands by the same amount in every direction in the π-plane, which is the plane that has its normal parallel to [111] in the deviatoric stress space (i.e., isotropic hardening); there is an associated flow rule, i.e., the strain increment is normal to the yield locus.
Axial electric wake field inside the induction gap exited by the intense electron beam
ZHANG Kai-Zhi; ZHANG Huang; LONG Ji-Dong; YANG Guo-Jun; HE Xiao-Zhong; WANG Hua-Cen
2008-01-01
While an intense electron beam passes through the accelerating gaps of a linear induction accelerator,a strong wake field will be excited.In this paper a relatively simple model is established based on the interaction between the transverse magnetic wake field and the electron beam,and the numerical calculation in succession generates a magnetic wake field distribution along the accelerator and along the beam pulse as well.The axial electric wake field is derived based on the relation between field components of a resonant mode.According to some principles in existence,the influence of this field on the high voltage properties of the induction gap is analyzed.The Dragon-I accelerator is taken as an example,and its maximum electric wake field is about 17 kV/cm,which means the effect of the wake field is noticeable.
Separation control using synthetic vortex generator jets in axial compressor cascade
Xinqian Zheng; Sheng Zhou; Anping Hou; Zhengli Jiang; Daijun Ling
2006-01-01
An experimental investigation conducted in a high-speed plane cascade wind tunnel demonstrates that unsteady flow control by using synthetic(zero mass flux)vortex generator jets can effectively improve the aerodynamic performances and reduce(or eliminate) flow separation in axial compressor cascade.The Mach number of the incoming flow is up to 0.7 and most tested cases are at Ma=0.3.The incidence is 10° at which the boundary layer is separated from 70% of the chord length.The roles of excitation frequency,amplitude,location and pitch angle are investigated.Preliminary results show that the excitation amplitude plays a very important role.The optimal excitation location is just upstream of the separation point,and the optimal pitch angle is 35°.The maximum relative reduction of loss coefficient is 22.8%.
The Multivariate Watson Distribution: Maximum-Likelihood Estimation and other Aspects
Sra, Suvrit
2011-01-01
This paper studies fundamental aspects of modelling data using multivariate Watson distributions. Although these distributions are natural for modelling axially symmetric data (i.e., unit vectors where $\\pm \\x$ are equivalent), for high-dimensions using them can be difficult. Why so? Largely because for Watson distributions even basic tasks such as maximum-likelihood are numerically challenging. To tackle the numerical difficulties some approximations have been derived---but these are either grossly inaccurate in high-dimensions (\\emph{Directional Statistics}, Mardia & Jupp. 2000) or when reasonably accurate (\\emph{J. Machine Learning Research, W. & C.P., v2}, Bijral \\emph{et al.}, 2007, pp. 35--42), they lack theoretical justification. We derive new approximations to the maximum-likelihood estimates; our approximations are theoretically well-defined, numerically accurate, and easy to compute. We build on our parameter estimation and discuss mixture-modelling with Watson distributions; here we uncover...
Dorival Pedroso da Silva
2010-01-01
Full Text Available The purpose of this research was to evaluate the maximum stress around osseointegrated implants and alveolar ridge, in a mandible with left partial resection through a photoelastic mandibular model. The first group consisted of two implants: traditional model (T, implants placed in the position of both canines; fulcrum model (F, implants placed in the position of left canine CL and right lateral incisor LiR. Both models linked through a bar and clips. The second group was consisted of three implants, with implants placed in the position of both canines (CR and CL and the right lateral incisor (LiR, which composed four groups: (1 model with 3 “O” rings, (2 model 2 ERAs, bar with clips, (3 model 2 ERAs bar without clips; (4 model “O” ring bar and ERA. An axial and an oblique load of 6.8 kgf was applied on a overdenture at the 1st Pm, 2nd Pm, and 1st M. Results showed that the area around the left canine (CL was practically free of stress; the left lateral incisor (LiL developed only small tensions, and low stress in all the other cases; the right canine tooth suffered the largest concentrations of stress, mainly with the ERA retention mechanism.
Zhu, Zhiwen; Zhang, Wendi; Xu, Jia
2014-01-01
A kind of shape memory alloy (SMA) hysteretic nonlinear model is developed, and the stochastic bifurcation characteristics of SMA intravascular stents subjected to radial and axial excitations are studied in this paper. A new nonlinear differential item is introduced to interpret the hysteretic phenomena of SMA strain-stress curves, and the dynamic model of SMA intravascular stent subjected to radial and axial stochastic excitations is established. The conditions of the system's stochastic stability are determined, and the probability density function of the system response is obtained. Finally, the stochastic Hopf bifurcation characteristics of the system are analyzed. Theoretical analysis and numerical simulation show that the system stability varies with bifurcation parameters, and stochastic Hopf bifurcation occurs in the process; there are two limit cycles in the stationary probability density of the system response in some cases, which means that there are two vibration amplitudes whose probability are both very high; jumping phenomena between the two vibration amplitudes appears with the change of conditions, which may cause stent fracture or loss. The results of this paper are helpful for application of SMA intravascular stent in biomedical engineering fields.
Reassessing the Plastic Hinge Model for Energy Dissipation of Axially Loaded Columns
R. M. Korol
2014-01-01
Full Text Available This paper investigates the energy dissipation potential of axially loaded columns and evaluates the use of a plastic hinge model for analysis of hi-rise building column collapse under extreme loading conditions. The experimental program considered seven axially loaded H-shaped extruded aluminum structural section columns having slenderness ratios that would be typical of floor-to-ceiling heights in buildings. All seven test specimens initially experienced minor-axis overall buckling followed by formation of a plastic hinge at the mid-height region, leading to local buckling of the flanges on the compression side of the plastic hinge, and eventual folding of the compression flanges. The experimental energy absorption, based on load-displacement relations, was compared to the energy estimates based on section plastic moment resistance based on measured yield stress and based on measured hinge rotations. It was found that the theoretical plastic hinge model underestimates a column’s actual ability to absorb energy by a factor in the range of 3 to 4 below that obtained from tests. It was also noted that the realizable hinge rotation is less than 180°. The above observations are based, of course, on actual columns being able to sustain high tensile strains at hinge locations without fracturing.
Jabulani R. Barber
2014-01-01
Full Text Available The mechanical response of thirteen different helical multi-walled carbon nanocoils to axial compression is reported. Each nanocoil was attached to the apex of a cantilever probe tip; its dimensions and orientation relative to the tip apex were determined with scanning electron microscopy. The atomic force microscope was employed to apply a cyclic axial load on the nanocoil. Its mechanical response was determined by simultaneous collection of the thermal resonance frequency, displacement, and oscillation amplitude of the cantilever-nanotube system in real time. Depending upon compression parameters, each coil underwent buckling, bending, and slip-stick motion. Characteristic features in the thermal resonance spectrum and in the force and oscillation amplitude curves for each of these responses to induced stress are presented. Following compression studies, the structure and morphology of each nanocoil were determined by transmission electron microscopy. The compression stiffness of each nanocoil was estimated from the resonant frequency of the cantilever at the point of contact with the substrate surface. From this value, the elastic modulus of the nanocoil was computed and correlated with the coiled carbon nanotube’s morphology.
Design Optimization of an Axial Fan Blade Through Multi-Objective Evolutionary Algorithm
Kim, Jin-Hyuk; Choi, Jae-Ho; Husain, Afzal; Kim, Kwang-Yong
2010-06-01
This paper presents design optimization of an axial fan blade with hybrid multi-objective evolutionary algorithm (hybrid MOEA). Reynolds-averaged Navier-Stokes equations with shear stress transport turbulence model are discretized by the finite volume approximations and solved on hexahedral grids for the flow analyses. The validation of the numerical results was performed with the experimental data for the axial and tangential velocities. Six design variables related to the blade lean angle and blade profile are selected and the Latin hypercube sampling of design of experiments is used to generate design points within the selected design space. Two objective functions namely total efficiency and torque are employed and the multi-objective optimization is carried out to enhance total efficiency and to reduce the torque. The flow analyses are performed numerically at the designed points to obtain values of the objective functions. The Non-dominated Sorting of Genetic Algorithm (NSGA-II) with ɛ -constraint strategy for local search coupled with surrogate model is used for multi-objective optimization. The Pareto-optimal solutions are presented and trade-off analysis is performed between the two competing objectives in view of the design and flow constraints. It is observed that total efficiency is enhanced and torque is decreased as compared to the reference design by the process of multi-objective optimization. The Pareto-optimal solutions are analyzed to understand the mechanism of the improvement in the total efficiency and reduction in torque.