1,596 research outputs found
Spin and charge modulations of a half-filled extended Hubbard model
We introduce and analyze an extended Hubbard model, in which intersite
Coulomb interaction as well as a staggered local potential (SLP) are
considered, on the square lattice at half band filling, in the thermodynamic
limit. Using both Hartree-Fock approximation and Kotliar and Ruckenstein slave
boson formalism, we show that the model harbors charge order (CO) as well as
joint spin and charge modulations (SCO) at finite values of the SLP, while the
spin density wave (SDW) is stabilized for vanishing SLP, only. We determine
their phase boundaries and the variations of the order parameters in dependence
on the SLP, as well as on the on-site and nearest-neighbor interactions.
Domains of coexistence of CO and SCO phases, suitable for resistive switching
experiments, are unraveled. We show that the novel SCO systematically turns
into the more conventional SDW phase when the zero-SLP limit is taken. We also
discuss the nature of the different phase transitions, both at zero and finite
temperature. In the former case, no continuous CO to SDW (or SCO) phase
transition occurs. In contrast, a paramagnetic phase (PM), which is accompanied
with continuous phase transitions towards both spin or charge ordered phases,
sets in at finite temperature. A good quantitative agreement with numerical
simulations is demonstrated, and a comparison between the two used approaches
is performed.Comment: 17 pages, 7 figure
Synthesis, properties and performance of organic polymers employed in flocculation applications
Flocculation is a common technique that is widely used in many industrial applications to promote solid–liquid separation processes. The addition of a polymeric flocculant allows for the destabilization of suspended colloidal particles, and thus significantly increases their sedimentation rate. Polymeric flocculants are generally divided into four categories, which include non-ionic, cationic, anionic, and amphoteric polymers. This minireview article summarises important information on the recent design and synthesis of polymeric materials from these four categories. In addition, their properties and flocculation efficiency are also presented and discussed
Synthesis of ultra-high molecular weight ABA triblock copolymers via aqueous RAFT-mediated gel polymerisation, end group modifications and chain coupling
The synthesis of ultra-high molecular weight (UHMW) polymers using reversible deactivation radical polymerisation techniques remains a challenge and has been the centre of attention only in a limited number of studies. Although UHMW polymers were synthesised in these research studies, the complexity in architecture has mainly been limited to linear homopolymers and AB diblock copolymers. We hereby report a new pathway to synthesise UHMW ABA triblock copolymers using a combination of reversible addition–fragmentation chain transfer (RAFT) polymerisation, end-group modification by aminolysis and chain coupling. A simple aqueous RAFT-mediated gel polymerisation technique was initially employed to synthesise high molecular weight AB diblock copolymers with low dispersities (Đ 1000k; Đ < 1.70)
Loop-corrected Higgs masses in the NMSSM with inverse seesaw mechanism
In this study, we work in the framework of the Next-to-Minimal extension of the Standard Model (NMSSM) extended by six singlet leptonic superfields. Through the mixing with the three doublet leptonic superfields, the non-zero tiny neutrino masses can be generated through the inverse seesaw mechanism. While R-parity is conserved in this model lepton number is explicitly violated. We quantify the impact of the extended neutrino sector on the NMSSM Higgs sector by computing the complete one-loop corrections with full momentum dependence to the Higgs boson masses in a mixed on-shell- DR ¯¯¯¯¯¯¯¯¯¯ renormalization scheme, with and without the inclusion of CP violation. The results are consistently combined with the dominant two-loop corrections at O(αt(αs+αt)) to improve the predictions for the Higgs mixing and the loop-corrected masses. In our numerical study we include the constraints from the Higgs data, the neutrino oscillation data, the charged lepton flavor-violating decays li→lj+γ, and the new physics constraints from the oblique parameters S, T, U. We present in this context the one-loop decay width for li→lj+γ. The loop-corrected Higgs boson masses are included in the Fortran code NMSSMCALC-nuSS
Short-term load forecasting using regression based moving windows with adjustable window-sizes
This paper presents a regression based moving window model for solving the short-term electricity forecasting problem. Moving window approach is employed to trace the demand pattern based on the past history of load and weather data. Regression equation is then formed and least square method is used to determine the parameters of the model. In this paper, a new concept associated with cooling and heating degree is used to establish the relationship between electricity demand and temperature, which is one of the key climatic variables. In addition, Pearson\u27s correlation has been employed to investigate the interdependency of electricity demand between different time periods. These analyses together with the data in the holiday period provide the supportive information for the appropriate selection of the window size. A case study has been reported in this paper by acquiring the relevant data for the state of New South Wales, Australia. The results are then compared with a neural network based model. The comparison shows that the proposed moving window approach with the different window sizes outperforms conventional neural network technique in small time scales i.e., from 30 minuntes to 1 day ahead
Impact of Farmers’ Adoption of Good Agricultural Products on Total Factor Productivity Change: The Case of Grape and Apple Production in Vietnam
Development of agricultural production with Good Agricultural Practices (GAP) standards is an objective trend of sustainable agriculture. This research employed data envelopment analysis (DEA) and ordinary least square (OLS) Regression to quantify impact of farmers’ adoption of GAP on the Total Factor Productivity Change (TFPCH) in investment in grape and apple production in Ninh Thuan of Vietnam. The results show that farmers’ adoption of GAP positively influenced on increase on total factor productivity. Therefore, it is necessary to find-out solutions to speed up farmers’ investment in development of agriculture with GAP standards. Keywords: GAP, TFPCH, impact, farmer household, Vietna
- …