scholarly journals Three-Dimensional Ultra-Short Base Line Based Underwater Acoustical Localization Utilizing Modified Newton Algorithm

IEEE Access ◽  
2021 ◽  
pp. 1-1
Author(s):  
Xiang Li ◽  
Xin Liu ◽  
Long Qu ◽  
Yi Lou ◽  
Sibo Sun
2021 ◽  
Author(s):  
Fergus Imrie ◽  
Thomas E. Hadfield ◽  
Anthony R. Bradley ◽  
Charlotte M. Deane

AbstractGenerative models have increasingly been proposed as a solution to the molecular design problem. However, it has proved challenging to control the design process or incorporate prior knowledge, limiting their practical use in drug discovery. In particular, generative methods have made limited use of three-dimensional (3D) structural information even though this is critical to binding. This work describes a method to incorporate such information and demonstrates the benefit of doing so. We combine an existing graph-based deep generative model, DeLinker, with a convolutional neural network to utilise physically-meaningful 3D representations of molecules and target pharmacophores. We apply our model, DEVELOP, to both linker and R-group design, demonstrating its suitability for both hit-to-lead and lead optimisation. The 3D pharmacophoric information results in improved generation and allows greater control of the design process. In multiple large-scale evaluations, we show that including 3D pharmacophoric constraints results in substantial improvements in the quality of generated molecules. On a challenging test set derived from PDBbind, our model improves the proportion of generated molecules with high 3D similarity to the original molecule by over 300%. In addition, DEVELOP recovers 10 × more of the original molecules compared to the base-line DeLinker method. Our approach is general-purpose, readily modifiable to alternate 3D representations, and can be incorporated into other generative frameworks. Code is available at https://github.com/oxpig/DEVELOP.


1988 ◽  
Vol 254 (4) ◽  
pp. H804-H810 ◽  
Author(s):  
F. X. Witkowski ◽  
P. A. Penkoske

Many current attempts at electrophysiological elucidation of cardiac arrhythmia mechanisms have centered around activation sequence mapping. This is most commonly performed with polarized unipolar or bipolar metal electrodes, which, because of unstable direct current (DC) base-line potentials, necessitate alternating current (AC)-coupled amplification. An ideal nonpolarizable unipolar electrode offers unhindered exchange of charge allowing for stable DC recordings of biological electrical activity. In addition to activation information, DC unipolar recordings enable quantitation of systolic and diastolic potentials, other low-frequency phenomena of interest such as repolarization, as well as rapid recovery from such rapid extreme potential shifts such as defibrillation. Previous attempts to apply nonpolarizable electrodes to transmural cardiac investigations required complex wick electrode techniques to prevent mechanical movement of the fluid-metal interface when chlorided silver wire was used. We have developed a technique to fabricate miniature sintered Ag-AgCl electrodes that are mounted at various locations on a 20-gauge stainless steel needle permitting stable transmural DC unipolar electrogram recordings in vivo. The electrodes are low noise, rugged, sterilizable, and reusable and should prove useful in three-dimensional electrophysiological characterization of the heart.


2012 ◽  
Vol 60 (5) ◽  
pp. 2431-2441 ◽  
Author(s):  
Aria Abubakar ◽  
Tarek M. Habashy ◽  
Guangdong Pan ◽  
Mao-Kun Li

Author(s):  
Bob Mischo ◽  
Andre´ Burdet ◽  
Thomas Behr ◽  
Reza S. Abhari

This paper presents a study of the impact of casing injection on the blade tip leakage. The investigation includes both the flow physics and the consequences on overall performance. With the use of three-dimensional CFD together with a feature-based injection model, the flow structure related to the injection is revealed inside the tip region. The effects on performance of different injection configurations are compared to a baseline configuration without injection. The predictions are validated with an extensive experimental database made available in a companion paper (GT2007-27269). A detailed investigation of flow physics changes in the tip region is presented for one injection configuration. It appears that the tip leakage vortex is shifted axially downward when injecting from the casing. Special attention is laid on the unsteady flow field that establishes due to the relative motion of the rotor and the stationary injection holes on the casing. Both time averaged data and instantaneous snapshots are used to reveal that the flow in the tip gap region, especially near the pressure side lip, appears to get a fluctuating character. It turns out that the tip gap mass flow is reduced by about 11% relatively to the base line when injecting from the casing. In addition, it fluctuates by as much as 1.4% over its mean value. As a corollary a fluctuation of the total injected fluid mass flow is found, of an order of 2.2%. A flow model synthesizing the observed phenomena is presented.


Author(s):  
A. Marn ◽  
E. Go¨ttlich ◽  
D. Cadrecha ◽  
H. P. Pirker

The demand of further increased bypass ratio of aero engines will lead to low pressure turbines with larger diameters which rotate at lower speed. Therefore, it is necessary to guide the flow leaving the high pressure turbine to the low pressure turbine at larger diameters minimising the losses and providing an adequate flow at the LP-turbine inlet. Due to costs and weight this intermediate turbine duct has to be as short as possible. This would lead to an aggressive (high diffusion) s-shaped duct geometry. It is possible to shorten the duct simply by reducing the length but the risk of separation is rising and losses increase. Another approach to shorten the duct and thus the engine length is to apply a so called integrated concept. These are novel concepts where the struts, mounted in the transition duct, replace the usually following LP-vane row. This configuration should replace the first LP-vane row from a front bearing engine architecture where the vane needs a big area to hold bearing services. That means the rotor is located directly downstream of the strut. This means that the struts have to provide the downstream blade row with undisturbed inflow with suitable flow angle and Mach number. Therefore, the (lifting) strut has a distinct three dimensional design in the more downstream part while in the more upstream part it has to be cylindrical to be able to lead through supply lines. In spite of the longer chord compared with the base design this struts have a thickness to chord ratio of 18%. To apply this concept a compromise must be found between the number of struts (weight), vibration, noise and occurring flow disturbances due to secondary flows and losses. The struts and the outer duct wall have been designed by ITP. The inner duct was kept the same as for the base line configuration (designed by MTU). The aim of the design was to have similar duct outflow conditions (exit flow angle and radial mass flow distribution) as the base design with which it is compared in this paper. This base design consists of a single transonic HP-turbine stage, an aggressive s-shaped intermediate turbine duct and an LP-vane row. Both designs used the same HP-turbine and were run in the continuously operating Transonic Test Turbine Facility (TTTF) at Graz University of Technology under the same engine representative inlet conditions. The flow field upstream and downstream the LP-vane and the strut, respectively has been investigated by means of five hole probes. A rough estimation of the overall duct loss is given as well as the upper and lower weight reduction limit for the integrated concept. This work is part of the EU-project AIDA (Aggressive Intermediate Duct Aerodynamics, Contract: AST3-CT-2003-502836).


1999 ◽  
Vol 35 (25) ◽  
pp. 2189 ◽  
Author(s):  
M.A. Player ◽  
J. van Weereld ◽  
A.R. Allen ◽  
D.A.L. Collie

1987 ◽  
Vol 87 (2) ◽  
pp. 241-248
Author(s):  
P.B. Noble

The locomotory trajectories of MOS-11 cells migrating in a three-dimensional hydrated collagen lattice have been determined using a computer-assisted optical sectioning unit. The trajectories have been quantified using a three-dimensional continuous-time Markov probability theory consisting of eight directional states and one stationary state; in the latter the cells are not locomoting. Markov analysis shows that these cells are locomoting in a random manner with regard to direction and remain stationary for about three times as long as they are locomoting. Analysis of persistence also implies random locomotion. Compilation of the distribution of angles between steps reveals that the cells exhibit a predilection for turns around 30 degrees and 150 degrees on either side of the previous step. Time-lapse video recordings show that the cells are bi-polar with ruffling membranes at opposite poles. Ruffling, and hence locomotion, occurs alternately at one pole and then the other, which would account for the distribution of angles encountered. The mean speed of the cells was of the order of 3 microns min-1 including the time stopped and approximately twice this if the time stopped (state 0) is not included. The results obtained provide base-line data on the locomotory characteristics of MOS-11 cells locomoting in a 1.2 mg ml-1 collagen gel. It is now possible to study the role of various matrix components in cell locomotion. Such studies are of importance to embryology, wound healing, host defence mechanisms and the invasion of cancer cells.


1986 ◽  
Vol 108 (2) ◽  
pp. 111-119 ◽  
Author(s):  
R. B. Little ◽  
H. W. Wevers ◽  
D. Siu ◽  
T. D. V. Cooke

A three-dimensional finite element model of the proximal tibia has been developed to provide a base line for further modeling of prosthetic resurfaced tibiae. The geometry for the model was developed by digitizing coronal and transverse sections made with the milling machine, from one fresh tibia of average size. The load is equally distributed between the medial and lateral compartments over contact areas that were reported in the literature. An indentation test has been used to measure the stiffness and the ultimate strength of cancellous bone in four cadaver tibiae. These values provided the statistical basis for characterising the inhomogeneous distribution of the cancellous bone properties in the proximal tibia. All materials in the model were assumed to be linearly elastic and isotropic. Mechanical properties for the cortical bone and cartilage have been taken from the literature. Results have been compared with strain gage tests and with a two-dimensional axisymmetric finite element model both from the literature. Qualitative comparison between trabecular alignment, and the direction of the principal compressive stresses in the cancellous bone, showed a good relationship. Maximum stresses in the cancellous bone and cortical bone, under a load which occurs near stance phase during normal gait, show safety factors of approximately eight and twelve, respectively. The load sharing between the cancellous bone and the cortical bone has been plotted for the first 40 mm distally from the tibial eminence.


1966 ◽  
Vol 25 ◽  
pp. 227-229 ◽  
Author(s):  
D. Brouwer

The paper presents a summary of the results obtained by C. J. Cohen and E. C. Hubbard, who established by numerical integration that a resonance relation exists between the orbits of Neptune and Pluto. The problem may be explored further by approximating the motion of Pluto by that of a particle with negligible mass in the three-dimensional (circular) restricted problem. The mass of Pluto and the eccentricity of Neptune's orbit are ignored in this approximation. Significant features of the problem appear to be the presence of two critical arguments and the possibility that the orbit may be related to a periodic orbit of the third kind.


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