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A method for energy modeling and simulation implementation of machine tools of selective laser melting
摘要： Additive manufacturing (AM) technologies are providing promising solutions to production of unique parts at reduced material and energy consumptions. However, recent studies show that the sustainable advantage of AM is not always achieved. For ensuring the sustainability of the AM processes, quantification and assessment of the levels of resource consumptions should be carried out at the design phase. To enable the energy prediction and evaluation of AM, this work proposes a method for energy modeling and simulation implementation of AM machines and applies the method to a machine tool of selective laser melting (SLM). Furthermore, the developed simulation approach is validated using an experimental comparison and has been applied in a use case to realize an energy efficiency-oriented AM process design.
关键词： bond graph,energy simulation,selective laser melting,additive manufacturing,power flow modeling
更新于2025-09-23 15:21:01
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Cardiac Computed Tomography 2.0
摘要： Computed tomography angiography (CTA) is now an established diagnostic option for patients with chest pain. It is a safe alternative to functional testing, provides diagnostic certainty, is a good gatekeeper for downstream invasive angiography, and increases the diagnostic yield when invasive angiography is eventually needed. CTA-driven care is associated with more relief of angina and generates optimal medical therapy associated with reduced death and myocardial infarction. However, CT angiography can lead to more cardiac catheterizations as well as more coronary revascularization. CTA shows good sensitivity, but also suffers from suboptimal specificity; thus, one cannot be sure, lacking other functional test results, that more revascularization procedures are necessary or beneficial compared to operating on lesions with demonstrated ischemia.
关键词： Fractional Flow Reserve,Myocardial Perfusion Imaging,Cardiac Computed Tomography,Coronary Artery Disease,CT Angiography
更新于2025-09-23 15:21:01
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Abrasive flow machining (AFM) finishing of conformal cooling channels created by selective laser melting (SLM)
摘要： Conformal cooling channels are widely adopted in the mold industry because of rapid and uniform cooling during injection molding. These complicated cooling channel geometries become feasible via selective laser melting (SLM) technology. However, the SLM fabricated internal channel surface shows high surface roughness of about 10 μm Ra. This rough surface can cause stress concentration, reducing the fatigue life of the mold. Therefore, the objective of this study is to investigate the surface finish of the SLM fabricated conformal channels by abrasive flow machining (AFM), which is widely used in the surface finishing of internal channels. To fulfill this objective, a combination of single/multiple and straight/helical channels for conformal cooling channel geometries are employed. Seven different types of conformal cooling channels (?3mm) inside the bar are fabricated using SLM. The bar is put in the AFM fixture, and the internal channels are polished by flowing AFM media (ULV50%-54) through the channel at the same extrusion pressure of 80 bars for ten cycles. Fourteen bars (seven before AFM and seven after AFM) are machined to have the internal channel surfaces exposed for surface roughness measurement. Surface topographies of the exposed surfaces of seven types of internal channels are obtained using focus variation microscopy. The areal roughness parameters, such as arithmetical mean height (Sa) on the internal channel surfaces before and after AFM. By comparing SLM as-built conformal channel surfaces with AFM finished ones, AFM is shown to be effective in improving all SLM conformal cooling channels’ arithmetical mean height, Sa. Areal roughness parameters, such as developed interfacial area ratio (Sdr), root mean square gradient (Sdq), reduced peak height (Spk), reduced valley height (Svk), and skewness (Ssk), on those internal surfaces, were found to be sensitive to surface finishing by AFM.
关键词： Conformal cooling channel,Selective laser melting (SLM),Abrasive flow machining (AFM),Straight/helical and single/multiple channels,Areal roughness parameters
更新于2025-09-23 15:21:01
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Porphyrins as Photoredox Catalysts in Csp2-H Arylations: Batch and Continuous Flow Approaches
摘要： We have investigated both batch and continuous flow photoarylations of enol-acetates to yield different α-arylated aldehyde and ketone building blocks by using diazonium salts as the aryl-radical source. Different porphyrins were used as SET photocatalysts, and photophysical as well as electrochemical studies were performed to rationalize the photoredox properties and suggest mechanistic insights. Notably, the most electron-deficient porphyrin (meso-tetra(pentafluorophenyl)porphyrin) shows the best photoactivity as an electron-donor in the triplet excited-state, which was rationalized by the redox potentials of excited states and the turnover of the porphyrins in the photocatalytic cycle. Scope, a two-step continuous protocol and multigram-scale reactions are also presented revealing a robust, cost-competitive and easy methodology, highlighting the significant potential of porphyrins as SET photocatalysts.
关键词： Diazonium Salts,Photoredox Catalysts,Porphyrins,Batch and Continuous Flow,Csp2-H Arylations
更新于2025-09-23 15:21:01
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Scaling-up UV-mediated Intramolecular-Photo-Dehydro-Diels-Alder reactions using a Homemade High-Performance Annular Continuous-Flow Reactor
摘要： In this communication, we present a self-made annular continuous-flow reactor, which can be used in the UV/Vis-range in an internal numbering-up manner. As a model reaction, we chose a powerful and batch scale-limited benzoannelation method, which is an intramolecular Photo-Dehydro-Diels-Alder (IMPDDA) reaction. The scaling-up potential of this particular photochemical benchmark reaction towards the preparation of macrocylic (1,7)naphthalenophanes by variation of selected flow parameters is presented.
关键词： flow photochemistry,scaling-up,photocycloaddition,Photo-Dehydro-Diels-Alder reaction
更新于2025-09-23 15:21:01
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Spectroscopic Analyses - Developments and Applications || Application of Flow-Injection Spectrophotometry to Pharmaceutical and Biomedical Analyses
摘要： The discovery of new drugs, especially when many samples have to be analyzed in the minimum of time, demand the improvement or development of new analytical methods. Various techniques may be employed for this purpose. In this context, this chapter gathers the collection of paper and represents the review of past work on spectrophotometric technique coupled to a continuous flow system to determine low concentrations of several chemical species in different kinds of pharmaceutical and biological samples. A short historical background of the flow-injection analysis technique and a brief discussion of the basic principles and potential are presented. Part of this chapter is devoted to describing the sample preparation techniques, principles, and figures of merit of analytical methods. Representative applications of flow-injection spectrophotometry to pharmaceutical and biomedical analysis are also described.
关键词： biomedical samples,flow-injection,pharmaceutical,spectrophotometry
更新于2025-09-23 15:21:01
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[IEEE 2018 25th IEEE International Conference on Image Processing (ICIP) - Athens, Greece (2018.10.7-2018.10.10)] 2018 25th IEEE International Conference on Image Processing (ICIP) - Scene-Adaptive Image Acquisition for Focus Stacking
摘要： Focus stacking is a promising technique to extend depth of field in general photography by fusing images captured at different focusing distances. In this paper, we propose a round-trip scene-adaptive image acquisition system to automatically capture focal stack and fuse a high quality all-in-focus image. Based on scene analysis, we cover entire depth range of the scene in the forward optical scanning and refine all objects’ focusing positions accurately in the backward scanning. With captured images, we firstly extract depth map and all-in-focus image with combination of max-gradient flow and blur kernel estimation. Secondly, a superpixel-level Gaussian Fitting is proposed to determine the next location to capture. Experiments on simulated data show that our method attain high quality all-in-focus image with fewer captured images.
关键词： all-in-focus,max-gradient-flow,image acquisition,superpixel,Gaussian-Fitting
更新于2025-09-23 15:21:01
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[IEEE 2017 5th RSI International Conference on Robotics and Mechatronics (ICRoM) - Tehran, Iran (2017.10.25-2017.10.27)] 2017 5th RSI International Conference on Robotics and Mechatronics (ICRoM) - Robustness Enhancement of optical flow sensors accuracy to surface texture variations using point tracking algorithm
摘要： Novel architecture of high precision localization using optical flow sensor (OFS) combined with Iterative Point Tracking Algorithm (IPTA) is proposed. This work focuses on attenuation of OFS' sensitivity dependency on texture of surface over which sensor is moving. The aim for the design of experimental setup is to verify how much a robustness of OFS’s sensitivity on various surfaces improves. In this regard, four different surfaces' texture including iron, paper, textile and granite stone is opted. Experimental results indicate that sensor's resolution via IPTA on surfaces of iron, paper, textile and granite stone respectively equal to 382, 460, 528 and 448 CPI. Optimal value of the algorithm parameters is calculated via Genetic Algorithm (GA). We show that IPTA is one of the effective algorithms that can enhance the robustness of OFS' resolution to surface's texture variations.
关键词： Optical flow sensor,point tracking algorithm,Surface Texture,high accuracy planar localization,Genetic algorithm
更新于2025-09-23 15:21:01
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Ocular blood flow by laser speckle flowgraphy to detect cerebral ischemia during carotid endarterectomy
摘要： Laser speckle flowgraphy (LSFG) is a noninvasive technique that can measure relative blood flow velocity in the optic fundus contributed by the ophthalmic artery, the main first branch originating from the internal carotid artery (ICA). The aim of this study was to assess the feasibility of ocular blood flow measurement by LSFG to detect ischemic stress due to carotid clamping during carotid endarterectomy (CEA). Nineteen patients undergoing CEA with ocular blood flow measurement by LSFG and intraoperative monitoring (IOM) were prospectively enrolled between August 2016 and March 2019. The mean blur rate (MBR) of ocular blood flow by LSFG, representing relative blood flow of the branch of the retinal artery originating from the optic nerve head, was compared between before and after carotid clamping during CEA. The correlation between the reduction ratio of MBR and the regional saturation oxygen (rSO2) index by near infrared spectroscopy was investigated. Ocular blood flow measurement by LSFG could not be performed in one patient with a severe cataract. In the other 18 patients, LSFG could be performed in all 106 sessions during surgery. The MBR reduction ratio between before and after carotid clamping ranged from ? 12 to 100%. The MBR reduction ratio was positively correlated with the rSO2 index (r = 0.694, 95% confidence interval: 0.336–0.877, p = 0.001). The MBR reduction ratio of ocular blood flow by LSFG after carotid clamping was significantly correlated with the rSO2 index. The ocular blood flow by LSFG could be considered an adjunct modality for evaluating cerebral ischemic tolerance during CEA.
关键词： Ocular blood flow,Laser speckle flowgraphy,Cerebral blood flow,Carotid endarterectomy
更新于2025-09-23 15:19:57
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Luminescence interference to two-colour toluene laser-induced fluorescence thermometry in a particle-laden flow
摘要： We present the use of two-colour toluene planar laser-induced fluorescence (LIF) to obtain spatially resolved measurements of the gas temperature ( T g ) in a particle-laden turbulent flow under sufficiently dense particle loading that the interference from laser interactions with the particles is significant. The effect of the ratio of volumetric flow rates of the particle phase to the gas phase ( ?? ) on the accuracy and precision of two-colour toluene LIF thermometry was systematically investigated for three particle materials, alumina, zinc activated zinc oxide (ZnO:Zn) and polymethyl methacrylate (PMMA), each of which has differing interactions with the excitation laser. The PMMA particles were spherical and mono-disperse with diameters of 6 to 40 μm , while the alumina and ZnO:Zn particles had diameters in the range 1–40? μm and 2–200?μm, respectively. The results show that the accuracy of the gas temperature measurement is insensitive to particle size for the PMMA particles, but dependent on the instantaneous particle loading. Importantly, reliable measurements can be performed in the dense two-way coupling regime, with the measurement being accurate to within 5?°C for ???<?2.5 × 10?4 for the PMMA particles and for ?? < 7.6 × 10?4 for the alumina and ZnO:Zn particles.
关键词： volumetric flow rates,gas temperature measurement,particle-laden flow,two-colour toluene LIF,particle materials
更新于2025-09-23 15:19:57