A new modulated structure consisting of periodic （1120） stacking faults （SFs） in the α-Fe2O3 nanowires （NWs） formed by the thermal oxidation of Fe foils is reported, using a combination of high-resolution trans...
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A new modulated structure consisting of periodic （1120） stacking faults （SFs） in the α-Fe2O3 nanowires （NWs） formed by the thermal oxidation of Fe foils is reported, using a combination of high-resolution transmission electron microscopy （HRTEM） observations and HRTEM image simulations. The periodicity of the modulated structure is 1.53 nm, which is ten times （3500） interplanar spacing and can be described by a shift of every ten （3500） planes with 1/2 the interplanar spacing of the （1120） plane. An atomic model for the Fe203 structure is proposed to simulate the modulated structure. HRTEM simulation results confirm that the modulated structure in α-Fe2O3 NWs is caused by SFs.
The paper addresses the coupled motion of a 6 degree of freedom robot and a snake-like dexterous manipulator (SDM) designed for the treatment of bone defects behind the implant during total hip arthroplasty revision s...
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The paper addresses the coupled motion of a 6 degree of freedom robot and a snake-like dexterous manipulator (SDM) designed for the treatment of bone defects behind the implant during total hip arthroplasty revision surgery. We have formulated the problem as a weighted, multi-objective constraint, linear optimization. A remote center of motion (RCM) acts as a virtual constraint for the robot. The coupled robot kinematics does not assume piecewise-constant curvature for the SDM. We have evaluated our method by simulating the coupled system inside a potential lesion area.
Positron emission tomography (PET) and magnetic resonance imaging (MRI) have revolutionized the disease characterization as they enable the simultaneous measurement of functional and anatomical information of the body...
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Positron emission tomography (PET) and magnetic resonance imaging (MRI) have revolutionized the disease characterization as they enable the simultaneous measurement of functional and anatomical information of the body. However, the whole body simultaneous PET/MRI has been limited by its high cost. To address this issue, we are developing an RF-transmissive PET insert system that can be inserted into an MRI system without requiring modifications to the MR hardware system. Our PET system prototype consists of 16 PET detector modules in a 32 cm ring pattern with small gaps between them. By using electro-optical signal transmission technology, the PET insert is electrically floating relative to the MRI RF ground which allows the PET detector insert to be RF-penetrable. The inter-modular gaps and the electrical floating enable the RF fields of MRI body coil to pass through with some attenuation. We performed 2D electromagnetic simulations and experiments in a 3-T MR system to understand the degree to which a ring of electrically floating Faraday cages facilitates the RF transmissivity. The electromagnetic simulation results showed that the grounded PET insert blocks the RF field while the electrically floating PET insert allows the RF field to uniformly transmit through the gaps with some attenuation. The MRI attenuation experiments showed that the transmit attenuation was -3.47 dB and similarly the receive attenuations were -3.40 and -3.94 dB for GE and SE sequences, respectively. We have shown from both simulations and experiments that the RF field of the MRI body coil can penetrate a PET ring through small inter-modular gaps, when the PET ring is electrically floating with respect to the MR system.
Electrical actuation is investigated in two kinds of chiral smectic liquid-crystal elastomers (LCEs) with different domain structures LCE1 and LCE2: The latter is better than the former in orientational order. Trackin...
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Electrical actuation is investigated in two kinds of chiral smectic liquid-crystal elastomers (LCEs) with different domain structures LCE1 and LCE2: The latter is better than the former in orientational order. Tracking fluorescent beads dispersed on the samples enables us to measure the two-dimensional strain tensors in ferroelectric elastomer films. It turns out that the electric-field-induced strain is polarity dependent and the type of molecular orientation responsible for the strain is specified. In LCE1 the shear strain is dominant, whereas in LCE2 it is comparable to the elongation strain, which is explained by the rotation of the principal axes. The essential differences of the two elastomers are observed in the eigenvalues of the strain tensors. The absolute values for LCE1 are larger than those for LCE2. The difference is discussed on the basis of the domain structures.
Assessing the validity of measurement/model comparisons in fisheries acoustics is difficult, due to the uncertainty in ground truth for acoustic measurements obtained in the open water. One way to overcome this is to ...
Assessing the validity of measurement/model comparisons in fisheries acoustics is difficult, due to the uncertainty in ground truth for acoustic measurements obtained in the open water. One way to overcome this is to utilize laboratory measurements, where fish school parameters may be more well known. The primary purpose of this work was to investigate the feasibility of measuring the acoustic properties of a small group of live fish in a laboratory tank using a steady state subtraction method [J. Acoust. Soc. Am. 112, 1366-1376 (2002)]. Transfer function measurements were obtained in a fresh water tank that contained an enclosed group of goldfish (Carassius auratus auratus), in order to describe their resonance scattering behavior. The experimental results were compared with an existing predictive model [J. Acoust. Soc. Am. 99, 196-208 (1996)], which incorporates both multiple scattering effects between fish, and coherent interaction of their individual scattered fields. Computational modeling, experimental details and data/model comparison will be presented. This technique can be extended to larger tanks and other fish species.
作者：
Ji WangBin ZhouX.Sherry LiuAaron J.FieldsArnav SanyalXiutao ShiMark AdamsTony M.KeavenyX.Edward GuoDepartment of Mechanical Engineering
University of California Berkeley Berkeley CA U.S.A. Department of Mechanical Engineering University of California Berkeley Berkeley CA U.S.A. Department of Applied Physics and Applied MathematicsColumbia University New York New York U.S.A. Bone Bioengineering Laboratory
Department of Biomedical Engineering Columbia University New York New YorkU.S.A. Bone Bioengineering Laboratory Department of Biomedical Engineering Columbia University New York New YorkU.S.A. McKay Orthopaedic Research Laboratory
Department of Orthopaedic Surgery University of Pennsylvania Philadelphia PA U.S.A. Department of Orthopaedic Surgery University of California San Francisco San Francisco CA U.S.A.
We apply r-p adaptive time-implicit Discontinuous Galerkin (DG) methods to 2-D hypersonic flow problems. Previous applications of DG method were limited to viscous hypersonic flows. Here we extend DG to chemically rea...
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