Search

This paper investigates the spatial distributions of electron beam-evaporated atoms and electron beam-induced plasma in the coating process. The materials evaporated by electron beams first form vapour and then a little of plasma is generated in the vapour. The spatial distributions of electron beam-induced atoms and plasma play an important role on the coating uniformity of composition and thickness. The radial distribution of coating deposition thickness of electron beam-evaporated atoms predicted by this study agrees with the available experimental data. The predicted distribution of ion density in the electron beam-induced plasma agrees with the available measured data. The results reveal that the normalized coating thicknesses at the divergence angle of 6 and 14 degrees of vapor source, respectively, are 0.8 and 0.2 of these at divergence angle of 0 degree of vapor source for titanium and aluminum evaporated separately. The similar tendency for the decreasing coating thickness with the radial distance is also obtained for the co-evaporation of aluminum, titanium, and copper. High rotation rate of substrate of vapor source leads to the small deposition rate. Most ions in the electron beam-induced plasma are attracted by electrons of the electon beam and are located at the neighbourhood of the beam region. Therefore, the ion and ion-attracted electron densities rapidly decrease with the increasing radial distance from the electron beam.

Cancer cells can be killed by magnetic-nanoparticles-induced hysteresis heat under an external alternating magnetic field. However, the hysteresis heat-induced temperature must be precisely controlled to prevent damages to the ambient normal tissue from cancer cells. Therefore, this study employs a heat model to analyze the variation of temperature with time in magnetic nanoparticles within cancer. Results show that the temperature increase with time predicted from this study is consistent with the available experimental data. The effect of anisotropy constant on temperature rise with time is presented. The anisotropy constant makes the behaviours of temperature variation significantly different.

The variation of the specific power-loss with the anisotropy constant takes an approximately exponential form when magnetic nanoparticles (MNPs) are subjected to external alternating magnetic fields, and the distribution of the specific power-loss along the anisotropy constant shifts with temperature. Furthermore, the rate of increase in the temperature of MNPs used for hyperthermia depends significantly on the specific power-loss. Hence, the temperature characteristics of hyperthermia are affected by the specific power-loss. In this work, we develop a thermal model to analyze the effect of specific power-loss on temperature characteristics in MNPs uses for tumor hyperthermia. The results predicted by using the thermal model in this study are consistent with the available experimental data. The rate of increase of the temperature evidently varies at different temperatures due to different specific power-losses. An abrupt temperature rise occurs at the highest value in the distribution of the specific power-loss versus anisotropy constant. On the other hand, a slow temperature rise occurs when the intersection between the anisotropy constant of the MNPs and the specific power-loss distribution along the anisotropy constant at a some certain temperature corresponds with low specific power-loss.

Magnetic nanoparticles (MNPs) subjected to external alternating magnetic field can induce heat in MNPs due to hysteresis, which is usually employed for tumor hyperthermia. An effective hyperthermia treatment should selectively kill the tumor cells without damaging the ambient healthy tissue. Hence, it is important for hyperthermia to correctly control the alternating magnetic field-induced temperature of MNPs in the tumor. This work develops a thermal model to analyze various forms of temperature-rise with time in magnetic nanoparticles for tumor hyperthermia. Results show that there are horizontal, linear rise, square root, exponential decay and abrupt temperature-rise lines with time in MNPs. The horizontal, linear rise, and square root temperature lines with time are consistent with the available experimental data. It is worthily noted that the form of abrupt temperaturerise with time can result in harm to the normal cells or tissue. If the abrupt temperature-rise does not be controlled and predicted well.

This paper analytically investigates an ultrashort pulsed laser nanoscale processing for aluminum nitride (AIN) and lead zirconate titanate (PZT) ceramics. Processing characteristics of an ultra-short pulsed laser is different from that of long-pulsed laser due to ultrahigh intensity, ultrahigh power, and ultrashort time. The ultrasmall processing for materials can achieved by an ultra-short pulsed laser. This study proposes a model to analyze an ultrashort pulsed laser nanoscale processing for aluminum nitride (AIN) and lead zirconate titanate (PZT) ceramics. The effects of optical penetration absorption and thermal diffusion on temperature are also discussed. The results reveal that the variation of ablation rate with laser fluences predicted by this work agrees with the available measured data for an ultrashort pulsed laser processing for AIN and PZT. For femtosecond lasers, the optical absorption and thermal diffusion, respectively, governs the ablated depth per pulse at the low and high laser fluences. The thermal diffusion length is small relative to the optical penetration depth for femtosecond laser. The optical penetration absorption governs the temperature in the workpiece. On the other hand, for the picosecond laser, the thermal diffusion length is large compared to the optical penetration depth. The thermal diffusion determines the temperature in the workpiece.

An ultra-fast pulsed laser for materials processing can obtain submicrometer- to nanometer-sized parts or patterns (precision or accuracy) because the heat cannot diffuse in time for an ultra-fast pulsed duration, and this causes a threshold of ablation in multi-photoabsorption. The optical and thermal effects significantly affect the processing quality of an ultrashort pulsed laser for materials. This study utilizes a Laplace transform method to display the optical and thermal effects on the temperature field and the ablated depth of an ultrashort pulsed laser processing of materials. The results reveal that If an ultrafast pulsed laser-induced heat can keep the irradiated region above the evaporated temperature until the thermal diffusion occurs in the lattice of materials, thermal ablation occurs. The optical ablation can get a better processing quality due to less thermal diffusion. This study theoretically elucidates that the depth of optical ablation approximates the product of an optical absorption length and the logarithm of the ratio of laser fluence to laser fluence threshold. It has also been shown that the optical and thermal ablation, respectively, occur in low and high laser fluence because the optical ablation depends directly on the main source of the incident ultrashort pulsed laser. However, the thermal ablation is determined by the residual heat directly from the incident ultrashort pulsed laser after the optical ablation. The increase rate of the ablated depth per pulse with laser fluence is actually lower at high laser fluences than that at low laser fluences because the thermal ablation using the residual heat directly from the incident ultrashort pulsed laser is governed at high laser fluences. This study will provide the closed-form of a solution that elucidate the direct optical ablation and sequent thermal ablation for the ultra-fast pulsed laser photo-thermal processing.

Characteristics of picosecond laser processing for poly(methyl methacrylate) (PMMA) are studied in this text. Poly(methyl methacrylate) (PMMA) can be applied to micro- or nano-scale electronic devices. Short-pulsed laser is usually used for noncontact processing of nanoscale patterning of poly(methyl methacrylate) (PMMA). This study considers optical energy of laser to be transferred into decomposition energy of poly(methyl methacrylate) (PMMA). Using the condition of the energy balance at the decomposition interface, the variation of the ablation rate with the logarithm of the laser fluence is calculated for poly(methyl methacrylate) (PMMA) and agrees with the measured data. This study also discusses parametric effects of poly(methyl methacrylate) (PMMA) on the variation of the ablation rate with the logarithm of the laser fluence.

Due to system deficiencies, the ethylene industry company of Sinopec Maoming Company, water purification plant mud scraper often led to transmission chain pulled off. In cognizance of this phenomenon, this paper presents a new control method which improved start method and off-chain automatic monitoring system by the inverter, the reliability and stability of system greatly improved. Practice has proved that the design fully meet the predicted requirements.

CeO 2 nanocrystals with different morphologies were synthesized by adjusting the pH value of the starting solution in water-in-oil microemulsion. The obtained samples were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), thermogravimetric analysis and different thermal analysis (TGA/DTA), Brunauer–Emmet–Teller (BET) surface area measurement, ultraviolet–visible absorption (UV–vis) spectroscopy and photoluminescence (PL) spectroscopy. Results show that the morphologies of CeO 2 were transformed from granular to spherical and to rod-like while the pH of the starting solution varied from 5 to 8 and to 11. All samples were indexed to the phase of CeO 2 and Ce(OH) 4 , and the molar ratio of CeO 2 to Ce(OH) 4 was deduced to be about 0.25. The morphologies of CeO 2 nanocrystals had but slight influence on their specific surface areas, UV–vis spectra and PL spectra. The band gap energies of different morphological samples were estimated by UV–vis spectroscopic method.

For the complex nonlinear model of photovoltaic cells, traditional evolution strategy is easy to fall into the local optimal and its identification time is too long when taking parameters identification, then the difference algorithm is proposed in this study, which is to solve the problems of parameter identification in photovoltaic cell model, where it is very difficult to achieve with other identification algorithms. In this method, the random data is selected as the initial generation; the successful evolution to the next generation is done through a certain strategy of difference algorithm, which can achieve the effective identification of control parameters. It is proved that the method has a good global optimization and the fast convergence ability, and the simulation results are shown that the differential evolution has high identification ability and it is an effective method to identify the parameters of photovoltaic cells, where the photovoltaic cells can be widely used in other places with these parameters.