[en] Electromagnetic form factors are fundamental quantities in describing the underlying electromagnetic structure of nucleons. While proton electromagnetic form factors have been determined with good precision, neutron form factors are known poorly, largely due to the lack of free neutron targets. Jefferson Lab Hall A experiment E95-001, a ''precise measurement of the transverse asymmetry A_T' from the quasielastic ³He(e, e') process,'' was therefore designed to determine precisely the neutron magnetic form factor, G_Mⁿ at low momentum transfer values and was successfully completed in Spring 1999. High precision A_T'data in the quasi-elastic region at Q² values of 0.1 to 0.6 (GeV/c)² were obtained using a high-pressure spin-exchange optically-pumped polarized ³He gas target with an average polarization of 30%, a longitudinally polarized e^- beam, and two High Resolution Spectrometers: HRSe and HRSh. HRSe was employed to detect scattered electrons from the quasi-elastic kinematic region, and HRSh was employed as a elastic polarimetry to monitor the product of the beam and target polarizations. The extraction of form factors is usually model-dependent. Significant constraints on theoretical calculations are provided bu additional high precision quasi-elastic asymmetry data at Q² values of 0.1 and 0.2 (GeV/c)² in ³He breakup region, where effects of final state interactions (FSI) and meson exchange currents (MEC) are expected to be large [71]. G_Mⁿ is extracted from a non-relativistic Faddeev calculation which includes both FSI and MEC at Q² values of 0.1 and 0.2 (GeV/c)². The uncertainties of G_Mⁿ at these Q² values are comparable to those of recent experiments with deuterium targets [58]. At the higher Q² values from this experiment, G_Mⁿ is extracted from Plane-Wave Impulsive Approximation (PWIA) calculations with a relatively large theoretical uncertainty of 2-4%. Thus a reliable extraction of G_Mⁿ from A(prime)_T at higher Q ² values (especially at Q² values of0.3 and 0.4 (GeV/c)²) requires improved theoretical calculations including FSI, MEC, and relativistic effects. However, those G_Mⁿ results extracted from PWIA at higher Q² values from the experiment still show overall a good agreement with the most recent deuterium measurements. The analysis of asymmetries and the extraction of G_Mⁿ from both the Faddeev calculations and the PWIA calculations are reported in this thesis

[en] During nuclear power plant operation, the coolant in the primary loop will decompose to hydrogen and oxygen under radiation condition. Oxygen will aggravate the corrosion of stainless steel in the primary loop, reducing the equipment reliability and increasing the radioactive activation products. Normally nuclear power plants use the primary loop hydrogen injection to inhibit the radiation decomposition of the primary coolant. Traditional nuclear power plant uses the chemical and volume control tank to reduce the pressure of coolant and inject low pressure hydrogen. AP1000 use the high-pressure hydrogen injection technology, because there is no chemical and volume control tank in AP1000 nuclear power plant. This paper introduces the current high-pressure hydrogen injection scheme used by AP1000, analyzes the possible problems during operation, and suggests the improved scheme. (authors)

[en] Nano-ceria coating was deposited onto a chromium oxide forming alloy through galvanostatic cathodic electro-deposition method in cerium nitrate electrolyte. The electrochemical behavior and influence of main deposition parameters of current density, deposition time, and temperature were studied. It was seen that the crystal size decreased with increasing of current density while micro-cracks were also observed at higher current density. Slightly increasing of crystal size and smoothing of surface morphology were seen with increasing of deposition time. It was reported that the bath temperature has the most significant effect on crystal size and surface morphology of the deposit. Green rust as corrosion product was also observed with deposition temperatures higher than 35 °C. Optimized deposition parameters were used to produce homogeneous, continuous and green rust-free coatings which enhance the oxidation resistance of alloy 230. The electro-deposition process was found to be an accessible and efficient method to prepare nano-crystalline ceria coating. - Highlights: • Electrodeposition was used to make ceria coating on a chromium oxide forming alloy; • Deposition parameters of current density, time and temperature were investigated; • Crystal size and morphology of coating vary with changing of deposition parameters; • Coating prepared with optimized parameters reduced oxidation rate of alloy 230.

[en] Highlights: • Volatiles, particularly proteins, play a key role in sludge combustion. • Sludge combustion performance varies with different sludge organic concentrations. • Carbohydrates significantly affect the combustion rate in the second stage. • Combustion performance of digested sludge is more negative compared with others. - Abstract: Wastewater treatment plants produce millions of tons of sewage sludge. Sewage sludge is recognized as a promising feedstock for power generation via combustion and can be used for energy crisis adaption. We aimed to investigate the quantitative effects of various sludge characteristics on the overall sludge combustion process performance. Different types of sewage sludge were derived from numerous wastewater treatment plants in Beijing for further thermogravimetric analysis. Thermogravimetric–differential thermogravimetric curves were used to compare the performance of the studied samples. Proximate analytical data, organic compositions, elementary composition, and calorific value of the samples were determined. The relationship between combustion performance and sludge composition was also investigated. Results showed that the performance of sludge combustion was significantly affected by the concentration of protein, which is the main component of volatiles. Carbohydrates and lipids were not correlated with combustion performance, unlike protein. Overall, combustion performance varied with different sludge organic composition. The combustion rate of carbohydrates was higher than those of protein and lipid, and carbohydrate weight loss mainly occurred during the second stage (175–300 °C). Carbohydrates have a substantial effect on the rate of system combustion during the second stage considering the specific combustion feature. Additionally, the combustion performance of digested sewage sludge is more negative than the others

[en] Highlights: • The copper surface with main face (220) has a better anti-corrosion ability. • The copper surface with main faces (200) and (111) show poor anti-corrosion ability. • More energetic electrons on (220) face lead it to be effectively protected. - Abstract: When the MBT"−:Cl"− ratio is 50–10:1 in a solution containing of NaCl and Na-MBT (sodium salt of 2-mercaptobenzothiazole), the copper sample-1 (S1) was passivated; when the ration is 10–5:1, it was corroded. The copper sample-2 (S2) had no anti-corrosive ability in all solutions with MBT"−:Cl"− = 50–5:1. First-principle calculation revealed that the Cu atoms of (220) face, the main face of S1, have more unsaturated and energetic electrons than that of (200) and (111) faces, the main faces of S2. The highest chemical activation of the (220) face leads the S1 surface to show a better anti-corrosive ability.

[en] Single crystals of 6H–SiC were irradiated at room temperature with 20 MeV carbon ions at fluences of 1.5 × 10¹⁵ and 6.0 × 10¹⁵ cm⁻². Raman measurements were performed to study irradiation induced damage and the in-depth damage profile of SiC. A clear change of damage from the surface down to the stopping region of carbon ions as simulated by SRIM is exhibited. The affected area as detected by Raman is in good agreement with SRIM predictions while a little shallower dpa profile is observed. The partial disorder defined in the present work as a function of depth is demonstrated. A shift of the position of the TO peak towards lower wavenumbers with in-depth damage and then to higher wavenumbers beyond the most damaged region indicates that tensile strain due to defects has a backward V-curve distribution. The damaged layer is subjected to a compressive in-plane stress associated with the out-of-plane strain and the magnitude of this stress also has a backward V-curve depth profile. The evolution of line width of the TO peak with depth clearly shows the density of defects reaches the higher level at the most damaged region. The Raman spectroscopy scanning technique is proved to be a powerful tool for profiling of crystal damage induced by high-energy ion implantation

[en] Highlights: • A composite-PCMs wall in a full-scale room was tested in three seasons. • A regular energy-saving wall was introduced for comparison. • A reduction of 24.32% and 10–30% of the cooling and heating loads was obtained. • 9–72% of the heat loss was reduced with air-conditioner off under winter cases. • 45–74% of interior wall surface temperature fluctuation was reduced in mid-seasons. - Abstract: This paper aims to evaluate the year-round applicability of a kind of composite-PCMs wall (PCM-wall). The test was carried out in a full-scale room with a net dimension of 3.25 m (L) ∗ 3.86 m (W) ∗ 2.91 m (H) in three seasons, and comparisons were made with a regular energy-saving wall. Specific thermal capacity of the PCM-bricks was carried out according to DSC tests. Then thermal performance mainly including of energy-saving effect during summer and winter, reduction of interior wall surface temperature fluctuation during midseason was investigated. Results showed a reduction of about 0.2 °C for the maximum interior wall surface temperature, a time delay of about 1–2 h and a reduction of 24.32% of the cooling load for the PCM-wall under summer conditions. For the midseason cases, the PCM-wall was under the phase transition temperature range and could completely resist the ambient thermal disturbance. Besides, fluctuation of the interior wall surface temperature could be effectively reduced. For the winter cases, the PCM-wall could reduce 10–30% of the heating load. Additionally, as for the cases where air-conditioner was off during daytime (8:30–18:30) or nighttime (18:00–9:00 (next day)), a reduction of 9–72% of the heat lost from the interior wall surface could be achieved. To summarize, the PCM-wall performed more excellent thermal behavior all the year round.

[en] Water-induced changes in the morphology and optical properties of an ultrathin Ag film (3 nm thickness) have been studied by use of ultraviolet-visible (UV-Vis) spectroscopy, atomic force microscopy (AFM) and surface-enhanced Raman scattering (SERS) spectroscopy. A confocal micrograph shows that infinite regular Ag rings with almost uniform size (4 μm) emerge on the film surface after the ultrathin Ag film was immersed into water. The AFM measurement further confirms that the Ag rings consist of some metal holes with pillared edges. The UV-Vis spectrum shows that an absorption band at 486 nm of the Ag film after the immersion in water (I-Ag film) blue shifts by 66 nm with a significant decrease in absorbance, which is attributed to the macroscopic loss of some Ag atoms and the change in the morphology of the Ag film. The polarized UV-Vis spectra show that a band at 421 nm due to the normal component of the plasmon oscillation blue shifts after immersing the ultrathin Ag film into water. This band is found to be strongly angle-dependent for p-polarized light, indicating that the optical properties of the ultrathin Ag film are changed. The I-Ag film is SERS-active, and the SERS enhancement depends on different active sites on the film surface. Furthermore, it seems that the orientation of an adsorbate is related to the morphology of the I-Ag film

[en] Sandwich-type MgB_2/Boron/MgB_2 Josephson junctions were fabricated using magnetron sputtering system. The rapid-anneal process was adopted to replace traditional way of annealing, trying to solve the problem of interdiffusion and oxidation with multilayer films. The boron film was used as barrier layer to avoid the introduction of impurities and improve reproducibility of the junctions. The bottom MgB_2 thin films deposited on c-plane sapphire substrate exhibits a critical temperature T_C of 37.5 K and critical current density J_C at 5 K of 8.7 × 10"6 A cm"−"2. From the XRD pattern, the bottom MgB_2 thin film shows c-axis orientation, whereas the top MgB_2 became polycrystalline as Boron barrier layer grown thicker. Therefore, all junction samples show lower T_C than single MgB_2 thin film. The junctions exhibit excellent quasiparticle characteristics with ideal dependence on temperature and Boron barrier thickness. Subharmonic gap structure was appeared in conductance characteristics, which was attributed to the multiple Andreev reflections (MAR). The result demonstrates great promise of this new fabrication technology for MgB_2 Josephson junction fabrication. - Highlights: • Sandwich-type MgB_2/Boron/MgB_2 Josephson junctions were fabricated. • The junctions were annealed after deposition with the rapid-anneal process. • The highest critical current is 25.3 mA at 5 K and remains non-zero near 25 K. • Subharmonic gap features can be observed in the dI/dV – V curves

[en] Highlights: • We report the combined effect of dual ion beam irradiated yttria-stabilized zirconia. • The displacement damage created by dual ion beam is simply additive. • MSDA model can explain the irradiation effects of dual ion beam. • YSZ is irradiation resistance under high irradiation fluence. - Abstract: The combined effect of dual ion beam irradiated yttria-stabilized zirconia was investigated through Rutherford backscattering spectrometry/channeling (RBS/C), high resolution X-ray diffraction (HRXRD), atomic force microscopy (AFM) and transmission electron microscopy (TEM). Compared with other experimental results of single ion beam irradiation, a multistep damage accumulation model can also explain the irradiation effects of dual ion beam. Irradiation damage created by Ar + He ions are simply additive and no synergy effect has been observed. The variation trends of step height and displacement damage are similar. The synergic effects of displacement damage between heavy recoil atoms and α-particle in nuclear waste matrices will not cause more serious damage than the sum of two kinds of ions. The two experimental damage peaks are consistent with those calculated using stopping and range of ions in matter (SRIM). Phase stability and irradiation resistance is further confirmed by high resolution transmission electron microscopy (HRTEM)