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Simulation of evaporation and propulsion of small particles in a laser beam
摘要： The technique of numerical simulation of laser surface evaporation of small particles ranging in size from tens to several millimeters falling into the field of laser radiation is developed. The interaction of a laser beam with solid or liquid particles freely flying in a gas-dispersed stream is accompanied by heating and evaporation of the material, which occurs only from the irradiated part of the particle surface. The result is a reactive force created by the laser, which depends on the characteristics of the radiation and the physical properties of the particle material. The technique allows describing the pre-threshold, near-threshold and super-threshold modes of evaporation and is designed to calculate the light propulsion force due to the vapor recoil pressure arising from the irradiated part of the particle surface in the range of Mach numbers to unity. The Meshcherskii equation is used to simulate the reactive acceleration of particles. It is shown that, in the case of a pulsed laser effect, the theory is in good agreement with experimental data on reactive acceleration of aluminum, corundum, and graphite particles. A distinctive feature of the technique is the ability to calculate the gas dynamic parameters of steam and recoil pressure in a wide range of the power density of the absorbed laser radiation from 10 to 10,000 GW/m2.
关键词： laser surface evaporation,reactive force,vapor recoil pressure,small particles,Meshcherskii equation
更新于2025-09-23 15:19:57
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Temperature measurement in double-sided laser-heated diamond anvil cell and reaction of carbon
摘要： In this work, a double-sided laser-heated diamond anvil cell facility for studies at extreme conditions of pressure and temperature that has been developed is described in detail. Phase transitions occurring at extreme conditions can be mapped by accurate measurements of pressure and temperature. Micrometer-sized diamond crystals having regular facets have been synthesized at a pressure of 18 GPa and temperature 1785 K, which is con?rmed by visual inspection, micro-Raman and ?eld emission scanning electron micrograph measurements. A low-temperature gradient is observed across the sample surface during the formation of micrometer-sized diamond crystals. Our observation restricts the use of steel gasket as it can react with carbon (C) transported from the diamond anvil. The reaction of C with one of the potential thermal insulating medium Al2O3 is observed in the X-ray diffraction measurements.
关键词： Laser-heated diamond anvil cell,High pressure,Reaction of carbon
更新于2025-09-23 15:19:57
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Visualising improved peritoneal perfusion at lower intra-abdominal pressure by fluorescent imaging during laparoscopic surgery: A randomised controlled study
摘要： Background: Laparoscopy is the gold standard for many surgical procedures and is embraced as minimally invasive surgery in the enhanced recovery after surgery programme. Lowering intra-abdominal pressure during laparoscopy may decrease the degree of surgical injury and further enhance patient outcomes. This study aims to assess the effect of low pressure pneumoperitoneum on peritoneal perfusion during laparoscopic surgery. Materials and methods: We performed a prospective randomized intervention study in 30 adults undergoing colorectal robot assisted laparoscopic surgery at a secondary care medical center in the Netherlands between June and December 2018. A 3 minute video recording of the parietal peritoneum was made with the Da Vinci? Firefly mode following intravenous injection of 0.2 mg/kg indocyanine green at a pneumoperitoneum pressure of 8, 12 or 16 mmHg. Observers were blinded for the level of intra-abdominal pressure that was used. Fluorescent intensity in [-] over time was extracted from each video in MATLAB. Time to reach maximal fluorescent intensity (TMFI) and maximum fluorescent intensity (MFI) were compared among groups. The study was registered at clinicaltrials.gov (NCTXXXXXXXX). Results: Mean TMFI was shorter at low pressure (8 mmHg) than standard pressure (12 and 16 mmHg): 44 ± 12 versus 58 ± 18 seconds (p=0.032), respectively. Mean MFI was higher at 8 mmHg than 12 and 16 mmHg (222 ± 25 versus 188 ± 54, p=0.033). Regression analysis identified intra-abdominal pressure, mean arterial pressure and female gender as significant predictors of peritoneal perfusion. Conclusion: Low pressure pneumoperitoneum was associated with improved perfusion of the parietal peritoneum. Current available evidence supported feasibility and enhanced postoperative recovery. Future investigations should focus on optimizing factors that facilitate lower intra-abdominal pressure and explore effects on other clinically relevant patient outcomes such as anastomotic leakage and immune homeostasis.
关键词： intra-abdominal pressure,ischemia-reperfusion injury,pneumoperitoneum,perfusion,laparoscopic surgery,immune homeostasis
更新于2025-09-23 15:19:57
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Laser Cutting Parameters Effect on 316L Stainless Steel Surface
摘要： Laser cutting is a cutting technology that enables fast processing in high precision. This technology utilizes high temperatures generated by engine to perform the cutting process. Selection of cutting parameters becomes the main factor to determine the cutting surface quality. Cutting parameters in the form of cutting speed and gas pressure are varied between 60 mm/minute - 100 mm/minute and 17 bar - 21 bar to examine the effect on surface character. The character of the laser-cutting surface on 316L series stainless steel material was observed related to the roughness, hardness and microstructure. The results showed that the parameters of cutting speed and gas pressure had an effect on the cutting surface. Changes in cutting speed has more effect on surface roughness while gas pressure has more effect on cutting surface hardness. Observations on the surface also illustrated that there were differences in cutting quality along with the deeper penetration performed by the laser.
关键词： gas pressure,hardness,cutting speed,surface roughness
更新于2025-09-23 15:19:57
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Microstructural investigation of inkjet printed Cu(In,Ga)Se2 thin film solar cell with improved efficiency
摘要： Inkjet printed copper indium gallium diselenide (CIGS) thin film solar cell has attracted tremendous attention because of its various technological benefits as a non-vacuum process. Focused efforts in selenization of inkjet printed films to make the process feasible, are desired. In this work, microstructural investigation of inkjet printed precursor film selenized by rapid thermal processing (RTP) is presented. The optimization of selenization time for transforming metal nitrates precursor ink to CIGS thin film is investigated. Based on the results, the growth mechanism to form CIGS from inkjet printed CIG precursor films is proposed. Systematic study on the molybdenum diselenide (MoSe2) phase evolution during the two-step atmospheric pressure selenization process at the CIGS-Mo interface and its effect on device performance are carried out. Non-uniform inter-diffusion of indium (In) and gallium (Ga) during selenization, resulting in double-layered CIGS, one of the major reason limiting the performance of the devices is investigated through XRD, Raman, FESEM, EDS and Mott-Schottky analysis. The significant improvement in device efficiency from 0.4% to 4.2% is achieved due to microstructural improvement in CIGS films. Investigation on the mechanism of microstructural growth with selenization time affecting final device performance is presenting in this work.
关键词： CIGS,Rapid thermal processing,Microstructural growth,Inkjet printing,Atmospheric pressure selenization
更新于2025-09-23 15:19:57
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Numerical simulation of a coupled system of Maxwell equations and a gas dynamic model
摘要： It is known that both linear and nonlinear optical phenomena can be produced when the plasmon in metallic nanostructures are excited by the external electromagnetic waves. In this work, a coupled system of Maxwell equations and a gas dynamic model including a quantum pressure term is employed to simulate the plasmon dynamics of free electron fluid in different metallic nanostructures using a discontinuous Galerkin method. Numerical benchmarks demonstrate that the proposed numerical method can simulate both the high order harmonic generation and the nonlocal effect from metallic nanostructures. Based on the switch-on-and-off investigation, we can conclude that the quantum pressure term in gas dynamics is responsible for the bulk plasmon resonance. In addition, for the dielectric-filled nano-cavity, a coupled effective polarization model is further adopted to investigate the optical behavior of bound electrons. Concerning the numerical setting in this work, a strengthened influence of bound electrons on the generation of high order harmonic waves has been observed.
关键词： quantum pressure,Discontinuous Galerkin method,Maxwell equations,nonlocal effect,high order harmonic generation,gas dynamic model
更新于2025-09-23 15:19:57
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Scanning atmospheric-pressure plasma jet treatment of nickel oxide with peak temperature of a??500 ?°C for fabricating pa??ia??n structure perovskite solar cells
摘要： Scanning atmospheric-pressure plasma jet (APPJ) treatment of nickel oxide with a peak temperature of 500 °C was performed for fabricating p–i–n structure perovskite solar cells (PSCs). APPJ post-treatment leading to enhanced light scattering in PSCs that in turn increases the haze of NiO on FTO glass, improves the cell efficiency. APPJ treatment on NiO also improves the wettability to facilitate the follow-up deposition of CH3NH3PbI3. This also leads to better PSC performance. X-ray photoelectron spectroscopy indicates that APPJ treatment results in fewer C–N bonds and reduced NiAc2 content, suggesting more complete conversion of the liquid precursor into NiO. With three APPJ scans, the average PCE improves from 11.91% to 13.47%, with the best-performing PSC achieving an efficiency of 15.67%.
关键词： X-ray photoelectron spectroscopy,light scattering,Scanning atmospheric-pressure plasma jet,perovskite solar cells,wettability,nickel oxide
更新于2025-09-23 15:19:57
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Growth of Single-Crystal Cd0.9Zn0.1Te Ingots Using Pressure Controlled Bridgman Method
摘要： We report growth of single-crystal Cd0.9Zn0.1Te ingots while using the pressure-controlled Bridgman method. The Cd pressure was controlled during growth to suppress its evaporation from the melt and reduce the size of Te inclusions in the as-grown crystals. The accelerated crucible rotation technique (ACRT) was used to suppress constitutional supercooling. The fast accelerating and slow decelerating rotation speeds were optimized. Two-inch Cd0.9Zn0.1Te single-crystal ingots without grain boundaries or twins were grown reproducibly. Glow discharge mass spectrometry results indicate the e?ective segregation coe?cients of Zn and In dopants are 1.24 and 0.18, respectively. The full width half maximum (FWHM) of X-ray rocking curve was approximately 22.5 ”, and the IR transmittance was approximately 61%, indicating high crystallinity. The mean size of the Te inclusions was approximately 13.4 μm. Single-crystal wafers were cut into 5 × 5 × 2 mm3 slices and then used to fabricate gamma ray detectors. The energy resolution and peak-to-valley ratio maps were constructed while using 59.5 keV gamma ray measurements, which proved the high uniformity of detection performance.
关键词： ACRT,CZT single-crystal ingot,pressure control,Bridgman method
更新于2025-09-23 15:19:57
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Cavitation inception pressure and bubble cloud formation due to the backscattering of high-intensity focused ultrasound from a laser-induced bubble
摘要： Cavitation bubble cloud formation due to the backscattering of high-intensity focused ultrasound (HIFU) from a laser-induced bubble in various water temperatures and dissolved oxygen (DO) has been investigated. A laser-induced bubble generated near the geometrical focus of HIFU is utilized to yield intense negative pressure by the backscattering. Optical observation with a high-speed video camera and pressure measurement with a fiber-optic probe hydrophone are conducted simultaneously to understand the forming process of a bubble cloud and corresponding pressure field by the backscattering. Optical observation shows that a bubble cloud grows stepwise forming multiple layers composed of tiny cavitation bubbles, and the cavitation inception position is consistent with the local minimum pressure position simulated with the ghost fluid method. The bubble cloud grows larger in the opposite direction of HIFU propagation, and the absolute value of the cavitation inception pressure decreases with an increase in water temperature. The linear correlation between cavitation inception pressure and water temperature agrees with that given by Vlaisavljevich, Xu, Maxwell, Mancia, Zhang, Lin, Duryea, Sukovich, Hall, Johnsen, and Cain [IEEE Trans. Ultrason. Ferroelectr. Freq. Control 63, 1064–1077 (2016)]. However DO has minor dependence on the cavitation inception pressure when DO is degassed sufficiently. Furthermore, the gas nucleus size that might exist in the experiment has been estimated by using bubble dynamics.
关键词： Dissolved oxygen,Water temperature,Bubble cloud formation,Cavitation inception pressure,Laser-induced bubble,High-intensity focused ultrasound,Cavitation
更新于2025-09-23 15:19:57
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Monitoring of type IV composite pressure vessels with multilayer fully integrated optical fiber based distributed strain sensing
摘要： We present the results of distributed fiber optic strain sensing for condition monitoring of a hybrid type IV composite fully wrapped pressure vessel using multilayer integrated optical fibers. Distributed strain sensing was performed for a total number of 252,000 load cycles until burst of the vessel. During this ageing test material fatigue could be monitored and spatially localized. Critical material changes were detected 17,000 cycles before material failure. Results have been validated by acoustic emission analysis.
关键词： Hybrid composite pressure vessel,Acoustic emission analysis,Structural health monitoring,Distributed fiber optic sensing
更新于2025-09-23 15:19:57