Hydromorphodynamics Simulation for Selected Stretch of Euphrates River within Al-Anbar Governorate

In this study, the hydromorphodynamic simulation of a stretch of the Euphrates River was conducted. The stretch of the Euphrates River extended from Haditha dam to the city of Heet in Al-Anbar Governorate and it is estimated to be 124.4 km. Samples were taken from 3 sites along the banks of the river stretch using sampling equipment. The samples were taken to the laboratory for grain size analysis where the median size (D50) and sediment load were determined. The hydromorphodynamic simulation was conducted using the NACY 2DH solver of the iRIC model.  The model was calibration using the Manning roughness,    sediment load, and median particle size and the validation process showed that the error between the simulation and the recorded data was minimum. After calibration, three different scenarios were considered and the scenarios were based on different river discharges (low, average, and flood discharge).  Four statistical indices were used to check the predicted values of the velocities and water depth in various sections of the Euphrates River section at the city of Heet and these indices were Mean Absolute Deviation (MAD), Mean Square Error (MSE), Root MSE (RMSE), and the Mean Absolute Percentage Error (MAPE). For velocity, values of the above indices for the first scenario were found to be 0.19, 0.046, 0.21, and 0.17 respectively. However, for water depth, values for the above statistical indices were found to be 0.07, 0.01, 0.01, and 0.13 respectively. The values confirmed the accuracy of the prediction of model iRIC Nacy2DH.

Air Curtain Design Optimization of Refrigerated Vertical Display Cabinet using CFD

This paper presents computational investigations to address some of the design parameters that have significant effects on the performance of the refrigerated display cabinets. These parameters include air curtain velocity, width, discharge angle and positioning of the air curtain outlet from the front edge of the top shelf, also the effect of using a honeycomb on the flow path at the air curtain outlet. A 3D CFD model was constructed to assess the effect of the side flow on the performance of the vertical display cabinet. The suitability of using 2D CFD to carry out the display cabinet design optimisation was also considered. Experimental work was then carried out to validate the numerical work: there was good agreement between the data generated from the numerical work with the experimental results. It was determined that for the length of the cabinet considered in this investigation, the flow can be assumed to be two-dimensional, for most of the cabinet length. The results also indicate that optimum air curtain mass flow rate should account for nearly a third of the total air mass flow rate inside the display cabinet

Spin-orbit coupling and the conservation of angular momentum

In nonrelativistic quantum mechanics, the total (i.e. orbital plus spin) angular momentum of a charged particle with spin that moves in a Coulomb plus spin-orbit-coupling potential is conserved. In a classical nonrelativistic treatment of this problem, in which the Lagrange equations determine the orbital motion and the Thomas equation yields the rate of change of the spin, the particle's total angular momentum in which the orbital angular momentum is defined in terms of the kinetic momentum is generally not conserved. However, a generalized total angular momentum, in which the orbital part is defined in terms of the canonical momentum, is conserved. This illustrates the fact that the quantum-mechanical operator of momentum corresponds to the canonical momentum of classical mechanics.Comment: 10 pages, as published by Eur. J. Phy

Relativistic Aharonov-Casher Phase in Spin One

The Aharonov-Casher (AC) phase is calculated in relativistic wave equations of spin one. The AC phase has previously been calculated from the Dirac-Pauli equation using a gauge-like technique \cite{MK1,MK2}. In the spin-one case, we use Kemmer theory (a Dirac-like particle theory) to calculate the phase in a similar manner. However the vector formalism, the Proca theory, is more widely known and used. In the presence of an electromagnetic field, the two theories are `equivalent' and may be transformed into one another. We adapt these transformations to show that the Kemmer theory results apply to the Proca theory. Then we calculate the Aharonov-Casher phase for spin-one particles directly in the Proca formalism.Comment: 12 page

Comment on `Electromagnetic force on a moving dipole'

Using the Lagrangian formalism, the electromagnetic force on a moving dipole derived by Kholmetskii, Missevitch and Yarman (2011, Eur. J. Phys. 32, 873) is found to be missing some important terms.Comment: The version as accepted by Eur. J. Phys.; 4 page

Hybrid THz architectures for molecular polaritonics

Physical and chemical properties of materials can be modified by a resonant optical mode. Such recent demonstrations have mostly relied on a planar cavity geometry, others have relied on a plasmonic resonator. However, the combination of these two device architectures have remained largely unexplored, especially in the context of maximizing light-matter interactions. Here, we investigate several schemes of electromagnetic field confinement aimed at facilitating the collective coupling of a localized photonic mode to molecular vibrations in the terahertz region. The key aspects are the use of metasurface plasmonic structures combined with standard Fabry-Perot configurations and the deposition of a thin layer of glucose, via a spray coating technique, within a tightly focused electromagnetic mode volume. More importantly, we demonstrate enhanced vacuum Rabi splittings reaching up to 200 GHz when combining plasmonic resonances, photonic cavity modes and low-energy molecular resonances. Furthermore, we demonstrate how a cavity mode can be utilized to enhance the zero-point electric field amplitude of a plasmonic resonator. Our study provides key insight into the design of polaritonic platforms with organic molecules to harvest the unique properties of hybrid light-matter states.Comment: 7 pages (5 Figures) + 7 pages Appendix (5 Figures), updated versio

A shift from cattle to camel and goat farming can sustain milk production with lower inputs and emissions in north sub-Saharan Africa’s drylands

Climate change is increasingly putting milk production from cattle-based dairy systems in north sub-Saharan Africa (NSSA) under stress, threatening livelihoods and food security. Here we combine livestock heat stress frequency, dry matter feed production and water accessibility data to understand where environmental changes in NSSA’s drylands are jeopardizing cattle milk production. We show that environmental conditions worsened for ∼17% of the study area. Increasing goat and camel populations by ∼14% (∼7.7 million) and ∼10% (∼1.2 million), respectively, while reducing the dairy cattle population by ∼24% (∼5.9 million), could result in ∼0.14 Mt (+5.7%) higher milk production, lower water (−1,683.6 million m3, −15.3%) and feed resource (−404.3 Mt, −11.2%) demand—and lower dairy emissions by ∼1,224.6 MtCO2e (−7.9%). Shifting herd composition from cattle towards the inclusion of, or replacement with, goats and camels can secure milk production and support NSSA’s dairy production resilience against climate change

Partial discharge detection using low cost RTL-SDR model for wideband spectrum sensing

Partial discharge (PD) is one of the predominant factors to be controlled to ensure reliability and undisrupted functions of power generators, motors, Gas Insulated Switchgear (GIS) and grid connected power distribution equipment, especially in the future smart grid. The emergence of wireless technology has provided numerous opportunities to optimise remote monitoring and control facilities that can play a significant role in ensuring swift control and restoration of HV plant equipment. In order to monitor PD, several approaches have been employed, however, the existing schemes do not provide an optimal approach for PD signal analysis, and are very costly. In this paper an RTL-SDR (Software Defined Radio) based spectrum analyser has been proposed in order to provide a potentially low cost solution for PD detection and monitoring. Initially, a portable spectrum analyser has been used for PD detection that was later replaced by an RTL-SDR device. The proposed schemes exhibit promising results for spectral detection within the VHF and UHF band

Analysis of human performance as a measure of mental fatigue

In our day to day, we often experience a sense of being tired due to mental or physical workload. Along with that, there is also a feeling of degrading performance, even after the completion of simple tasks. These mental states however, are often not felt consciously or are ignored. This is an attitude that may result in human error, failure, and may lead to potential health problems together with a decrease in quality of life. States of acute mental fatigue may be detected with the close monitoring of certain indicators, such as productivity, performance and health indicators. In this paper, a model and prototype are proposed to detect and monitor acute acute fatigue, based on non-invasive Humancomputer Interaction (HCI). This approach will enable the development of better working environments, with an impact on the quality of life and the work produced.This work was developed in the context of the project CAMCoF - Contextaware Multimodal Communication Framework funded by ERDF - European Regional Development Fund through the COMPETE Programme (operational programme for competitiveness) and by National Funds through the FCT - Funda ção para a Ciência e a Tecnologia (Portuguese Foundation for Science and Technology) within project FCOMP-01-0124-FEDER-028980