Characterization of highly-oriented ferroelectric Pb_xBa_(1-x)TiO_3

Pb_xBa_(1-x)TiO_3 (0.2 ≾ x ≾ 1) thin films were deposited on single-crystal MgO as well as amorphous Si_3N_4/Si substrates using biaxially textured MgO buffer templates, grown by ion beam-assisted deposition (IBAD). The ferroelectric films were stoichiometric and highly oriented, with only (001) and (100) orientations evident in x-ray diffraction (XRD) scans. Films on biaxially textured templates had smaller grains (60 nm average) than those deposited on single-crystal MgO (300 nm average). Electron backscatter diffraction (EBSD) has been used to study the microtexture on both types of substrates and the results were consistent with x-ray pole figures and transmission electron microscopy (TEM) micrographs that indicated the presence of 90° domain boundaries, twins, in films deposited on single-crystal MgO substrates. In contrast, films on biaxially textured substrates consisted of small single-domain grains that were either c or a oriented. The surface-sensitive EBSD technique was used to measure the tetragonal tilt angle as well as in-plane and out-of-plane texture. High-temperature x-ray diffraction (HTXRD) of films with 90° domain walls indicated large changes, as much as 60%, in the c and a domain fractions with temperature, while such changes were not observed for Pb_xBa_(1-x)TiO_3 (PBT) films on biaxially textured MgO/Si_3N_4/Si substrates, which lacked 90° domain boundaries

The Quark-Gluon Plasma Equation of State and The Generalized Uncertainty Principle

The quark-gluon plasma (QGP) equation of state within a minimal length scenario or Generalized Uncertainty Principle (GUP) is studied. The Generalized Uncertainty Principle is implemented on deriving the thermodynamics of ideal QGP at a vanishing chemical potential. We find a significant effect for the GUP term. The main features of QCD lattice results were quantitatively achieved in case of $n_{f}=0$, $n_{f}=2$ and $n_{f}=2+1$ flavors for the energy density, the pressure and the interaction measure. The exciting point is the large value of bag pressure especially in case of $n_{f}=2+1$ flavor which reflects the strong correlation between quarks in this bag which is already expected. One can notice that, the asymptotic behavior which is characterized by Stephan-Boltzmann limit would be satisfied.Comment: 9 Pages, 8 figure

Graded ferroelectric capacitors with robust temperature characteristics

Ferroelectric thin films offer the possibility of engineering the dielectric response for tunable components in frequency-agile rf and microwave devices. However, this approach often leads to an undesired temperature sensitivity. Compositionally graded ferroelectric films have been explored as a means of redressing this sensitivity, but experimental observations vary depending on geometry and other details. In this paper, we present a continuum model to calculate the capacitive response of graded ferroelectric films with realistic electrode geometries by accurately accounting for the polarization distribution and long-range electrostatic interactions. We show that graded c-axis poled BaxSr_(1−xT)iO_3 BST parallel plate capacitors are ineffective while graded a-axis poled BST coplanar capacitors with interdigitated electrodes are extremely effective in obtaining high and temperature-stable dielectric properties

The impact of digitization on the religious sphere:televangelism as an example

Over the past few decades, televangelism has emerged as one important media phenomenon, inter alia, among Muslim communities. As a phenomenon, televangelism is interesting in many respects; it is a manifestation of the phenomenon of "info-tainment" as televangelists integrate entertainment features such as sound effects and music in their sermons. It is also a manifestation of the rise of the celebrity culture as televangelists have become 'media celebrities' with thousands of hundreds of fans and followers on social media networks. Thematically, this study is divided into two main sections. First. I delineate the characteristics of televangelism as a novel form of religious expression in which televangelists adopt a modern style and use colloquial language; and in which televangelists present religion as a source of individual change. I have argued that these features seem to have granted televangelists popularity particularly among Muslim youth who view televangelism as a new form of religious expression that is modern in appearance and relevant to their everyday lives. The study has further highlighted the importance of digital media technologies in popularizing televangelists' programmes and sermons. Drawing on two case studies of popular televangelists, namely Amr Khaled and Hamza Yusuf, the study has shown that televangelists draw on a plethora of digital media tools to extend the visibility of their programmes including websites and social media networks. The study has found that televangelists' fans play an important role in popularizing televangelists' programmes. Moreover, the study relates televangelism to the rise of digital Islam. The study has argued that digitization and the increase of literacy rates have changed the structure of religious authority in the twenty first century, giving rise to new voices that are competing for authority. Having provided an explanatory framework for the phenomenon of televangelism, the study moves in the second section to critique televangelism. Drawing on Carrette and King's Selling Spirituality, one issue that the study raises is the extent to which televangelism fits into the modern form of 'spiritualities'. Rather than being a critical reflection of the consumer culture, modern spiritualities seem to 'smooth out' resistance to the hegemony of capitalism and consumerism. I have proposed that it is through a content-related analysis of televangelists' sermons that one can get a nuanced understanding of how the discourses of particular televangelists can possibly relate to dominant (capitalist) ideologies, how structures of power are represented in their discourses and what their texts may reveal about the socio-historical contexts of Muslims in the twenty first century

New sensing methods for scheduling variable rate irrigation to improve water use efficiency and reduce the environmental footprint : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Soil Science at Massey University, Palmerston North, New Zealand

Figures are re-used under an Attribution 4.0 International (CC BY 4.0) license, or are not copyrighted.Irrigation is the largest user of allocated freshwater, so conservation of water use should begin with improving the efficiency of crop irrigation. Improved irrigation management is necessary for humid areas such as New Zealand in order to produce greater yields, overcome excessive irrigation and eliminate nitrogen losses due to accelerated leaching and/or denitrification. The impact of two different climatic regimes (Hawkes Bay, Manawatū) and soils (free and imperfect drainage) on irrigated pea (Pisum sativum., cv. ‘Ashton’) and barley (Hordeum vulgare., cv. ‘Carfields CKS1’) production was investigated. These experiments were conducted to determine whether variable-rate irrigation (VRI) was warranted. The results showed that both weather conditions and within-field soil variability had a significant effect on the irrigated pea and barley crops (pea yield - 4.15 and 1.75 t/ha; barley yield - 4.0 and 10.3 t/ha for freely and imperfectly drained soils, respectively). Given these results, soil spatial variability was characterised at precision scales using proximal sensor survey systems: to inform precision irrigation practice. Apparent soil electrical conductivity (ECa) data were collected by a Dualem-421S electromagnetic (EM) survey, and the data were kriged into a map and modelled to predict ECa to depth. The ECa depth models were related to soil moisture (θv), and the intrinsic soil differences. The method was used to guide the placement of soil moisture sensors. After quantifying precision irrigation management zones using EM technology, dynamic irrigation scheduling for a VRI system was used to efficiently irrigate a pea crop (Pisum sativum., cv. ‘Massey’) and a French bean crop (Phaseolus vulgaris., cv. ‘Contender’) over one season at the Manawatū site. The effects of two VRI scheduling methods using (i) a soil water balance model and (ii) sensors, were compared. The sensor-based technique irrigated 23–45% less water because the model-based approach overestimated drainage for the slower draining soil. There were no significant crop growth and yield differences between the two approaches, and water use efficiency (WUE) was higher under the scheduling regime based on sensors. ii To further investigate the use of sensor-based scheduling, a new method was developed to assess crop height and biomass for pea, bean and barley crops at high field resolution (0.01 m) using ground-based LiDAR (Light Detection and Ranging) data. The LiDAR multi-temporal, crop height maps can usefully improve crop coefficient estimates in soil water balance models. The results were validated against manually measured plant parameters. A critical component of soil water balance models, and of major importance for irrigation scheduling, is the estimation of crop evapotranspiration (ETc) which traditionally relies on regional climate data and default crop factors based on the day of planting. Therefore, the potential of a simpler, site-specific method for estimation of ETc using in-field crop sensors was investigated. Crop indices (NDVI, and canopy surface temperature, Tc) together with site-specific climate data were used to estimate daily crop water use at the Manawatū and Hawkes Bay sites (2017-2019). These site-specific estimates of daily crop water use were then used to evaluate a calibrated FAO-56 Penman-Monteith algorithm to estimate ETc from barley, pea and bean crops. The modified ETc–model showed a high linear correlation between measured and modelled daily ETc for barley, pea, and bean crops. This indicates the potential value of in-field crop sensing for estimating site-specific values of ETc. A model-based, decision support software system (VRI–DSS) that automates irrigation scheduling to variable soils and multiple crops was then tested at both the Manawatū and Hawkes Bay farm sites. The results showed that the virtual climate forecast models used for this study provided an adequate prediction of evapotranspiration but over predicted rainfall. However, when local data was used with the VRI–DSS system to simulate results, the soil moisture deficit showed good agreement with weekly neutron probe readings. The use of model system-based irrigation scheduling allowed two-thirds of the irrigation water to be saved for the high available water content (AWC) soil. During the season 2018 – 2019, the VRI–DSS was again used to evaluate the level of available soil water (threshold) at which irrigation should be applied to increase WUE and crop water productivity (WP) for spring wheat (Triticum aestivum L., cv. ‘Sensas’) on the sandy loam and silt loam soil zones at the Manawatū site. Two irrigation thresholds (40% and 60% AWC), were investigated in each soil zone along with a rainfed control. Soil water uptake pattern was affected mainly by the soil type rather than irrigation. The soil iii water uptake decreased with soil depth for the sandy loam whereas water was taken up uniformly from all depths of the silt loam. The 60% AWC treatments had greater irrigation water use efficiency (IWUE) than the 40% AWC treatments, indicating that irrigation scheduling using a 60% AWC trigger could be recommended for this soil-crop scenario. Overall, in this study, we have developed new sensor-based methods that can support improved spatial irrigation water management. The findings from this study led to a more beneficial use of agricultural water

Standard Calculation of Fault Current Contribution of Doubly Fed Induction Generator-Based Wind Turbine

The fault current contribution of the doubly fed induction generator-based wind turbines (DFIG-WTs) is dictated by a combination of factors, including the electrical parameters of the machine and the controller configuration of the converters. A detailed manufacturer-based simulation model for DFIG-WT was used for detailed analysis of the controller influences on short-circuit parameters. Based on the analysis, new approximate expressions of the short-circuit parameters were introduced and a new mathematical model of the short-circuit current were developed. The mathematical models and the expressions were later validated using nonlinear optimization for parameter extraction. Subsequently, a new method was introduced for fault current contribution calculation in a simple and reliable way similar to IEC-60909. The method is based on linearization and a newly introduced correction factor that takes the influence of the controller into account. Finally, the new introduced method was tested on a small wind farm and the results show better accuracy in comparison with IEC-60909