- 标题
- 摘要
- 关键词
- 实验方案
- 产品
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SCExAO/CHARIS Near-IR High-contrast Imaging and Integral Field Spectroscopy of the HIP 79977 Debris Disk
摘要： We present new, near-infrared (1.1–2.4 μm) high-contrast imaging of the bright debris disk surrounding HIP 79977 with the Subaru Coronagraphic Extreme Adaptive Optics system (SCExAO) coupled with the CHARIS integral field spectrograph. SCExAO/CHARIS resolves the disk down to smaller angular separations of (0.11; r ～ 14 au) and at a higher significance than previously achieved at the same wavelengths. The disk exhibits a marginally significant east–west brightness asymmetry in H band that requires confirmation. Geometrical modeling suggests a nearly edge-on disk viewed at a position angle of ～114°.6 east of north. The disk is best-fit by scattered-light models assuming strongly forward-scattering grains (g ～ 0.5–0.65) confined to a torus with a peak density at r0 ～ 53–75 au. We find that a shallow outer density power law of αout = ?1 to ?3 and flare index of β = 1 are preferred. Other disk parameters (e.g., inner density power law and vertical scale height) are more poorly constrained. The disk has a slightly blue intrinsic color and its profile is broadly consistent with predictions from birth ring models applied to other debris disks. While HIP 79977?s disk appears to be more strongly forward-scattering than most resolved disks surrounding 5–30 Myr old stars, this difference may be due to observational biases favoring forward-scattering models for inclined disks versus lower inclination, ostensibly neutral-scattering disks like HR 4796A’s. Deeper, higher signal-to-noise SCExAO/CHARIS data can better constrain the disk’s dust composition.
关键词： stars: individual (HIP 79977),circumstellar matter,techniques: high angular resolution,planetary systems
更新于2025-09-23 15:23:52
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Automatic hip geometric feature extraction in dxa imaging using regional random forest
摘要： BACKGROUND: Hip fracture is considered one of the salient disability factors across the global population. People with hip fractures are prone to become permanently disabled or die from complications. Although currently the premier determiner, bone mineral density has some notable limitations in terms of hip fracture risk assessment. OBJECTIVES: To learn more about bone strength, hip geometric features (HGFs) can be collected. However, organizing a hip fracture risk study for a large population using a manual HGFs collection technique would be too arduous to be practical. Thus, an automatic HGFs extraction technique is needed. METHOD: This paper presents an automated HGFs extraction technique using regional random forest. Regional random forest localizes landmark points from femur DXA images using local constraints of hip anatomy. The local region constraints make random forest robust to noise and increase its performance because it processes the least number of points and patches. RESULTS: The proposed system achieved an overall accuracy of 96.22% and 95.87% on phantom data and real human scanned data respectively. CONCLUSION: The proposed technique’s ability to measure HGFs could be useful in research on the cause and facts of hip fracture and could help in the development of new guidelines for hip fracture risk assessment in the future. The technique will reduce workload and improve the use of X-ray devices.
关键词： contour traversing,random forest,DXA imaging system,hip geometric features
更新于2025-09-19 17:15:36
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[IEEE 2019 International Conference on Optical MEMS and Nanophotonics (OMN) - Daejeon, Korea (South) (2019.7.28-2019.8.1)] 2019 International Conference on Optical MEMS and Nanophotonics (OMN) - Electromagnetic FPCB micromirror scanning laser rangefinder
摘要： Since several years, the number of total hip arthroplasty revision surgeries is substantially growing. One of the main reasons for this procedure to become necessary is the loosening or damage of the prothesis, which is facilitated by bone necrosis at the implant–bone interface. Electrostimulation is one promising technique, which can accelerate the growth of bone cells and, therefore, enhance the anchorage of the implant to the bone. We present computational models of an electrostimulative total hip revision system to enhance bone regeneration. In this study, the influence of uncertainty in the conductivity of bone tissue on the electric field strength and the beneficial stimulation volume for an optimized electrode geometry and arrangement is investigated. The generalized polynomial chaos technique is used to quantify the uncertainty in the stimulation volumes with respect to the uncertain conductivity of cancellous bone, bone marrow, and bone substitute, which is used to fill defective areas. The results suggest that the overall beneficial stimulation areas are only slightly sensitive to the uncertainty in conductivity of bone tissue. However, in the proximity of tissue boundaries, larger uncertainties, especially in the transition between beneficial and understimulation areas, can be expected.
关键词： Electrical stimulation,finite-element method,multiobjective optimization,uncertainty quantification,total hip arthroplasty (THA) revision
更新于2025-09-19 17:13:59
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Research on Post-processing Microstructure and Property of Titanium Components with Selective Laser Melting (SLM)
摘要： Additive manufacturing of titanium component holds promise to deliver benefit such as reduced cost, weight and carbon emissions during both manufacture and use. To capitalize on the benefits, it must be shown that the mechanical performance of parts produced by additive manufacturing can meet design requirement that are typically based on wrought material performance properties. Of particular concern for safety critical structures is the fatigue property of parts produced by additive manufacturing. Microstructure evolution, and its influence on mechanical properties of the alloy in the as-fabricated condition, has been documented by various researchers. However, fatigue crack propagation and the effects of the directional structure have not been sufficiently studied, imposing a barrier for this technology’s potential extension to high-integrity applications. In this study, fatigue life (S-N) and fatigue crack growth (FCG) both parallel and perpendicular to the build directions was studied. The interaction between the directional as-fabricated SLM microstructure and FCG was investigated and compared to that of the hot isostatic pressing (HIP) specimens with and without the stress relief after fabricating with SLM.
关键词： Titanium Components,Selective Laser Melting (SLM),Hot Isostatic Pressing (HIP),Fatigue Property,Microstructure
更新于2025-09-19 17:13:59
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Evolution of the Structure and Properties of High-Chromium Heat-Resistant VZh159 Alloy Prepared by Selective Laser Melting: Part II
摘要： The evolution of the structural-phase state of the VZh159 alloy fabricated by selective laser melting after various types of thermal exposure and hot isostatic pressing (HIP) is studied. The effect of a long 500-h exposure at temperatures of 800 and 900°C on the phase composition and morphology of structural components is determined. The short-term and long-term strength of the material in various conditions are studied. It is shown that the segregation of dispersed particles of the σ phase after the gas-static treatment followed by aging and after prolonged exposure at high temperatures does not have a significant negative effect on the plastic and strength characteristics of the alloy. The long-term strength of the synthesized metal after the 500-h exposure at a temperature of 900°C corresponds to the certified values for the deformed semifinished product of the VZh159 alloy.
关键词： boride,heat treatment,σ-phase,HIP,gas-static treatment,VZh159,selective laser melting (SLM),transmission electron microscopy,cellular structure
更新于2025-09-19 17:13:59
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[IEEE 2019 21st International Middle East Power Systems Conference (MEPCON) - Cairo, Egypt (2019.12.17-2019.12.19)] 2019 21st International Middle East Power Systems Conference (MEPCON) - Optimal Allocation of Reactive Power Compensation in a Distribution Network with Photovoltaic System Integration
摘要： Since several years, the number of total hip arthroplasty revision surgeries is substantially growing. One of the main reasons for this procedure to become necessary is the loosening or damage of the prothesis, which is facilitated by bone necrosis at the implant–bone interface. Electrostimulation is one promising technique, which can accelerate the growth of bone cells and, therefore, enhance the anchorage of the implant to the bone. We present computational models of an electrostimulative total hip revision system to enhance bone regeneration. In this study, the influence of uncertainty in the conductivity of bone tissue on the electric field strength and the beneficial stimulation volume for an optimized electrode geometry and arrangement is investigated. The generalized polynomial chaos technique is used to quantify the uncertainty in the stimulation volumes with respect to the uncertain conductivity of cancellous bone, bone marrow, and bone substitute, which is used to fill defective areas. The results suggest that the overall beneficial stimulation areas are only slightly sensitive to the uncertainty in conductivity of bone tissue. However, in the proximity of tissue boundaries, larger uncertainties, especially in the transition between beneficial and understimulation areas, can be expected.
关键词： Electrical stimulation,finite-element method,multiobjective optimization,uncertainty quantification,total hip arthroplasty (THA) revision
更新于2025-09-19 17:13:59
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Evolution of the Structure and Properties of High-Chromium Heat-Resistant VZh159 Alloy Prepared by Selective Laser Melting: Part I
摘要： The evolution of the structural-phase state of the VZh159 alloy fabricated by selective laser melting after various types of thermal exposure and hot isostatic pressing (HIP) is studied. The effect of a long 500-h exposure at temperatures of 800 and 900°C on the phase composition and morphology of structural components is determined. The short-term and long-term strength of the material in various conditions are studied. It is shown that the segregation of dispersed particles of the σ phase after the gas-static treatment followed by aging and after prolonged exposure at high temperatures does not have a significant negative effect on the plastic and strength characteristics of the alloy. The long-term strength of the synthesized metal after the 500-h exposure at a temperature of 900°C corresponds to the certified values for the deformed semifinished product of the VZh159 alloy.
关键词： σ phase,VZh159,HIP,heat treatment,boride,transmission electron microscopy,gas-static treatment,selective laser melting (SLM),cellular structure
更新于2025-09-19 17:13:59
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Laser Resonance Frequency Analysis: A Novel Measurement Approach to Evaluate Acetabular Cup Stability During Surgery
摘要： Artificial joint acetabular cup stability is essential for successful total hip arthroplasty. However, a quantitative evaluation approach for clinical use is lacking. We developed a resonance frequency analysis (RFA) system involving a laser system that is fully contactless. This study aimed to investigate the usefulness of laser RFA for evaluating acetabular cup stability. First, the finite element method was performed to determine the vibration mode for analysis. Second, the acetabular cup was press-fitted into a reamed polyurethane cavity that replicated the human acetabular roof. The implanted acetabular cup was vibrated with pulse laser irradiation and the induced vibration was detected with a laser Doppler vibrometer. The time domain signal from the vibrometer was analyzed by fast Fourier transform to obtain the vibration frequency spectrum. After laser RFA, the pull-down force of the acetabular cup was measured as conventional implant fixation strength. The frequency of the first highest amplitude between 2 kHz and 6 kHz was considered as the resonance peak frequency, and its relationship with the pull-down force was assessed. The peak frequency could predict the pull-down force (R2 = 0.859, p < 0.000). Our findings suggest that laser RFA might be useful to measure acetabular cup stability during surgery.
关键词： implant stability,laser,resonance frequency analysis,total hip arthroplasty,finite element method,acetabular cup
更新于2025-09-16 10:30:52
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Laser dimple texturing – applications, process, challenges, and recent developments: a review
摘要： Laser dimple texturing has been a surge in the surface to surface contact applications like the cutting tool/workpiece interaction, piston-cylinder assembly, bearings, prosthetic hip & knee joints, blanking punch- die assembly, etc. to control the friction and wear between the interactions. In this article, the first part presented about a broad literature review on an effect of dimple texture in various industrial applications like bio-implant components and cutting tools. In the second part, detailed information has discussed on a process of laser dimple texturing and influence of laser process parameters such as laser wavelength, laser energy, number of pulses, pulse duration and focal distance on dimple geometry. The third part describes a comprehensive literature review on challenges/limitations of laser dimple texturing process like heat affected zone, tensile residual stresses, bulges around the dimple, etc. Finally, in the fourth part, proper attention has given on recent developments like laser shock peen texturing, laser texturing under water and post-processing techniques to overcome the limitations of laser surface texturing process.
关键词： Friction,Hip & knee joints,Wear,Cutting tool,Laser peen texturing,Heat affected zone,Laser dimple texture
更新于2025-09-12 10:27:22
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Effect of Hot Isostatic Pressing on Al-10%Si-0.4%Mg Alloy Fabricated by Selective Laser Melting; レーザ積層造形により作製したAl-10%Si-0.4%Mg合金における熱間等方加圧処理の影響;
摘要： In this study, we investigated the effects of hot isostatic pressing (HIP) on the mechanical properties of an Al-10%Si-0.4%Mg alloy fabricated by selective laser melting (SLM). In addition, the effect of internal porosity on the mechanical properties of the alloy was also investigated. After the HIP, the internal porosity of the alloy decreased, while its elongation to failure (EL) improved significantly. However, the 0.2% proof stress (PS) and the tensile strength (TS) of the HIPed alloy were significantly lower than those of the as-built state. This can be attributed to the microstructural changes that occurred at elevated temperatures during the HIP. In addition, the PS and TS of the as-built alloy decreased with an increase in the internal porosity. On the other hand, in the case of the HIPed alloy, the PS and TS were not affected by the internal porosity. However, EL was sensitive to the internal porosity. The EL of the HIPed alloy decreased with an increase in its initial internal porosity. This is because the diffusion bonding during the HIP was imperfect owing to the presence of oxidized scales. Hence, it is imperative to optimize the laser irradiation conditions for the fabrication of aluminum alloy by SLM.
关键词： aluminum alloy,selective laser melting (SLM),hot isostatic pressing (HIP),additive manufacturing (AM),internal porosity
更新于2025-09-11 14:15:04