Abstract: We present a theoretical investigation on the structural,
electronic properties and vibrational mode of nitrogen impurities
in ZnO. The atomic structures, formation and transition energies
and vibrational modes of (NO3)i interstitial or NO4 substituting
on an oxygen site ZnO were computed using ab initio total energy
methods. Based on Local density functional theory, our calculations
are in agreement with one interpretation of bound-excition
photoluminescence for N-doped ZnO. First-principles calculations
show that (NO3)i defects interstitial or NO4 substituting on an
Oxygen site in ZnO are important suitable impurity for p-type doping
in ZnO. However, many experimental efforts have not resulted in
reproducible p-type material with N2 and N2O doping. by means of
first-principle pseudo-potential calculation we find that the use of NO
or NO2 with O gas might help the experimental research to resolve
the challenge of achieving p-type ZnO.
Abstract: The climate change causes a change in all aspects of society. While the expansion of renewable energies proceeds, industry could not be convinced based on general studies about the potential of demand side management to reinforce smart grid considerations in their operational business. In this article, a procedure model for a case-specific data-driven decision support for industrial energy management based on a holistic data analytics approach is presented. The model is executed on the example of the strategic decision problem, to integrate the aspect of renewable energies into industrial energy management. This question is induced due to considerations of changing the electricity contract model from a standard rate to volatile energy prices corresponding to the energy spot market which is increasingly more affected by renewable energies. The procedure model corresponds to a data analytics process consisting on a data model, analysis, simulation and optimization step. This procedure will help to quantify the potentials of sustainable production concepts based on the data from a factory. The model is validated with data from a printer in analogy to a simple production machine. The overall goal is to establish smart grid principles for industry via the transformation from knowledge-driven to data-driven decisions within manufacturing companies.
Abstract: The current work aims to study the rainbow like-structure observed in the elastic scattering of alpha particles on both 12C and 16O nuclei. We reanalyzed the experimental elastic scattering angular distributions data for α+12C and α+16O nuclear systems at different energies using both optical model and double folding potential of different interaction models such as: CDM3Y1, DDM3Y1, CDM3Y6 and BDM3Y1. Potential created by BDM3Y1 interaction model has the shallowest depth which reflects the necessity to use higher renormalization factor (Nr). Both optical model and double folding potential of different interaction models fairly reproduce the experimental data.
Abstract: Continuous carbon fiber reinforced plastics (CFRP) exhibit a high application potential for lightweight structures due to their outstanding specific mechanical properties. Embedded metal elements, so-called inserts, can be used to join structural CFRP parts. Drilling of the components to be joined can be avoided using inserts. In consequence, no bearing stress is anticipated. This is a distinctive benefit of embedded inserts, since continuous CFRP have low shear and bearing strength. This paper aims at the investigation of the load bearing capacity after preinduced damages from impact tests and thermal-cycling. In addition, characterization of mechanical properties during dynamic high speed pull-out testing under different loading velocities was conducted. It has been shown that the load bearing capacity increases up to 100% for very high velocities (15 m/s) in comparison with quasi-static loading conditions (1.5 mm/min). Residual strength measurements identified the influence of thermal loading and preinduced mechanical damage. For both, the residual strength was evaluated afterwards by quasi-static pull-out tests. Taking into account the DIN EN 6038 a high decrease of force occurs at impact energy of 16 J with significant damage of the laminate. Lower impact energies of 6 J, 9 J, and 12 J do not decrease the measured residual strength, although the laminate is visibly damaged - distinguished by cracks on the rear side. To evaluate the influence of thermal loading, the specimens were placed in a climate chamber and were exposed to various numbers of temperature cycles. One cycle took 1.5 hours from -40 °C to +80 °C. It could be shown that already 10 temperature cycles decrease the load bearing capacity up to 20%. Further reduction of the residual strength with increasing number of thermal cycles was not observed. Thus, it implies that the maximum damage of the composite is already induced after 10 temperature cycles.
Abstract: The interest in air conditioning using renewable energies is increasing. The thermal energy produced from the solar energy can be converted to useful cooling and heating through the thermochemical or thermophysical processes by using thermally activated energy conversion systems. The ambient air contains so much water that very high dehumidification rates are required. For a continuous dehumidification of the process air, the water adsorbed on the desiccant material has to be removed, which is done by allowing hot air to flow through the desiccant material (regeneration). A solid desiccant cooling system transfers moisture from the inlet air to the silica gel by using two processes: Absorption process and the regeneration process. The main aim of this paper is to study how the dehumidification rate, the generation temperature and many other factors influence the efficiency of a solid desiccant system by using TRNSYS software. The results show that the desiccant system could be used to decrease the humidity rate of the entering air.
Abstract: The total mass attenuation coefficients m/r, of some halides such as, NaCl, KCl, CuCl, NaBr, KBr, RbCl, AgCl, NaI, KI, AgBr, CsI, HgCl2, CdI2 and HgI2 were determined at photon energies 279.2, 320.07, 514.0, 661.6, 1115.5, 1173.2 and 1332.5 keV in a well-collimated narrow beam good geometry set-up using a high resolution, hyper pure germanium detector. The mass attenuation coefficients and the effective atomic cross sections are found to be in good agreement with the XCOM values. From these mass attenuation coefficients, the effective atomic cross sections sa, of the compounds were determined. These effective atomic cross section sa data so obtained are then used to compute the effective atomic numbers Zeff. For this, the interpolation of total attenuation cross-sections of photons of energy E in elements of atomic number Z was performed by using the logarithmic regression analysis of the data measured by the authors and reported earlier for the above said energies along with XCOM data for standard energies. The best-fit coefficients in the photon energy range of 250 to 350 keV, 350 to 500 keV, 500 to 700 keV, 700 to 1000 keV and 1000 to 1500 keV by a piecewise interpolation method were then used to find the Zeff of the compounds with respect to the effective atomic cross section sa from the relation obtained by piece wise interpolation method. Using these Zeff values, the electron densities Nel of halides were also determined. The present Zeff and Nel values of halides are found to be in good agreement with the values calculated from XCOM data and other available published values.
Abstract: This paper reports the effects of laser energy on the characteristics of bubbles generated in the weld zone and the formation of new chemical bonds at the Polyethylene Terephthalate (PET)/Ti joint interface in laser joining of PET to Ti. The samples were produced by using different laser energies ranging from 1.5 J – 6 J in steps of 1.5 J, while all other joining parameters remained unchanged. The types of chemical bonding at the joint interface were analysed by the x-ray photoelectron spectroscopy (XPS) depth-profiling method. The results show that the characteristics of the bubbles and the thickness of the chemically bonded interface, which contains the laser generated bonds of Ti–C and Ti–O, increase markedly with increasing laser energy input. The tensile failure load of the joint depends on the combined effect of the amount and distribution of the bubbles formed and the chemical bonding intensity of the joint interface.
Abstract: The ionization yield of ion tracks in polymers and bio-molecular systems reaches a maximum, known as the Bragg peak, close to the end of the ion trajectories. Along the path of the ions through the materials, many electrons are generated, which produce a cascade of further ionizations and, consequently, a shower of secondary electrons. Among these, very low energy secondary electrons can produce damage in the biomolecules by dissociative electron attachment. This work deals with the calculation of the energy distribution of electrons produced by protons in a sample of polymethylmethacrylate (PMMA), a material that is used as a phantom for living tissues in hadron therapy. PMMA is also of relevance for microelectronics in CMOS technologies and as a photoresist mask in electron beam lithography. We present a Monte Carlo code that, starting from a realistic description of the energy distribution of the electrons ejected by protons moving through PMMA, simulates the entire cascade of generated secondary electrons. By following in detail the motion of all these electrons, we find the radial distribution of the energy that they deposit in PMMA for several initial proton energies characteristic of the Bragg peak.
Abstract: A hybrid energy system is a combination of renewable energy sources with back up, as well as a storage system used to respond to given load energy requirements. Given that the electrical output of each renewable source is fluctuating with changes in weather conditions, and since the load demand also varies with time; one of the main attributes of hybrid systems is to be able to respond to the load demand at any time by optimally controlling each energy source, storage and back-up system. The induced optimization problem is to compute the optimal operation control of the system with the aim of minimizing operation costs while efficiently and reliably responding to the load energy requirement. Current optimization research and development on hybrid systems are mainly focusing on the sizing aspect. Thus, the aim of this paper is to report on the state-of-the-art of optimal operation control of hybrid renewable energy systems. This paper also discusses different challenges encountered, as well as future developments that can help in improving the optimal operation control of hybrid renewable energy systems.
Abstract: Wireless Sensor Networks (WSNs) have many advantages. Their deployment is easier and faster than wired sensor networks or other wireless networks, as they do not need fixed infrastructure. Nodes are partitioned into many small groups named clusters to aggregate data through network organization. WSN clustering guarantees performance achievement of sensor nodes. Sensor nodes energy consumption is reduced by eliminating redundant energy use and balancing energy sensor nodes use over a network. The aim of such clustering protocols is to prolong network life. Low Energy Adaptive Clustering Hierarchy (LEACH) is a popular protocol in WSN. LEACH is a clustering protocol in which the random rotations of local cluster heads are utilized in order to distribute energy load among all sensor nodes in the network. This paper proposes Connected Dominant Set (CDS) based cluster formation. CDS aggregates data in a promising approach for reducing routing overhead since messages are transmitted only within virtual backbone by means of CDS and also data aggregating lowers the ratio of responding hosts to the hosts existing in virtual backbones. CDS tries to increase networks lifetime considering such parameters as sensors lifetime, remaining and consumption energies in order to have an almost optimal data aggregation within networks. Experimental results proved CDS outperformed LEACH regarding number of cluster formations, average packet loss rate, average end to end delay, life computation, and remaining energy computation.
Abstract: Elastic scattering of Protons and deuterons from 11B nuclei at different p, d energies have been analyzed within the framework of optical model code (ECIS88). The elastic scattering of 3He+11B nuclear system at different 3He energies have been analyzed using double folding model code (FRESCO). The real potential obtained from the folding model was supplemented by a phenomenological imaginary potential, and during the fitting process the real potential was normalized and the imaginary potential optimized. Volumetric integrals of the real and imaginary potential depths (JR, JW) have been calculated for 3He+11B system. The agreement between the experimental data and the theoretical calculations in the whole angular range is fairly good. Normalization factor Nr is calculated in the range between 0.70 and 1.236.
Abstract: The reduction of GHG emissions in buildings is a focus area of national energy policies in Europe, because buildings are responsible for a major share of the final energy consumption. It is at local scale where policies to increase the share of renewable energies and energy efficiency measures get implemented. Municipalities, as local authorities and responsible entity for land-use planning, have a direct influence on urban patterns and energy use, which makes them key actors in the transition towards sustainable cities. Hence, synchronizing urban planning with energy planning offers great potential to increase society’s energy-efficiency; this has a high significance to reach GHG-reduction targets. In this paper, the actual linkage of urban planning and energy planning in Denmark and Germany was assessed; substantive barriers preventing their integration and driving factors that lead to successful transitions towards a holistic urban energy planning procedures were identified.
Abstract: A torsional piezoelectric ultrasonic transducer design
is proposed to measure shear moduli in soft tissue with direct
access availability, using shear wave elastography technique. The
measurement of shear moduli of tissues is a challenging problem,
mainly derived from a) the difficulty of isolating a pure shear wave,
given the interference of multiple waves of different types (P, S,
even guided) emitted by the transducers and reflected in geometric
boundaries, and b) the highly attenuating nature of soft tissular
materials. An immediate application, overcoming these drawbacks,
is the measurement of changes in cervix stiffness to estimate the
gestational age at delivery. The design has been optimized using
a finite element model (FEM) and a semi-analytical estimator of
the probability of detection (POD) to determine a suitable geometry,
materials and generated waves. The technique is based on the time
of flight measurement between emitter and receiver, to infer shear
wave velocity. Current research is centered in prototype testing and
validation. The geometric optimization of the transducer was able
to annihilate the compressional wave emission, generating a quite
pure shear torsional wave. Currently, mechanical and electromagnetic
coupling between emitter and receiver signals are being the research
focus. Conclusions: the design overcomes the main described
problems. The almost pure shear torsional wave along with the short
time of flight avoids the possibility of multiple wave interference.
This short propagation distance reduce the effect of attenuation, and
allow the emission of very low energies assuring a good biological
security for human use.
Abstract: This paper presents the modeling and the control of a grid-connected photovoltaic system (PVS). Firstly, the MPPT control of the PVS and its associated DC/DC converter has been analyzed in order to extract the maximum of available power. Secondly, the control system of the grid side converter (GSC) which is a three-phase voltage source inverter (VSI) has been presented. A special attention has been paid to the control algorithms of the GSC converter during grid voltages imbalances. Especially, three different control objectives are to achieve; the mitigation of the grid imbalance adverse effects, at the point of common coupling (PCC), on the injected currents, the elimination of double frequency oscillations in active power flow, and the elimination of double frequency oscillations in reactive power flow. Simulation results of two control strategies have been performed via MATLAB software in order to demonstrate the particularities of each control strategy according to power quality standards.
Abstract: Elastic scattering of α-particles from 9Be and 11B
nuclei at different alpha energies have been analyzed. Optical model
parameters (OMPs) of α-particles elastic scattering by these nuclei at
different energies have been obtained. In the present calculations, the
real part of the optical potential are derived by folding of nucleonnucleon
(NN) interaction into nuclear matter density distribution of
the projectile and target nuclei using computer code FRESCO. A
density-dependent version of the M3Y interaction (CDM3Y6), which
is based on the G-matrix elements of the Paris NN potential, has been
used. Volumetric integrals of the real and imaginary potential depth
(JR, JW) have been calculated and found to be energy dependent.
Good agreement between the experimental data and the theoretical
predictions in the whole angular range. In double folding (DF)
calculations, the obtained normalization coefficient Nr is in the range
0.70–1.32.
Abstract: This research work presents the surface
thermodynamics approach to M-TB/HIV-Human sputum
interactions. This involved the use of the Hamaker coefficient
concept as a surface energetics tool in determining the interaction
processes, with the surface interfacial energies explained using van
der Waals concept of particle interactions. The Lifshitz derivation for
van der Waals forces was applied as an alternative to the contact
angle approach which has been widely used in other biological
systems. The methodology involved taking sputum samples from
twenty infected persons and from twenty uninfected persons for
absorbance measurement using a digital Ultraviolet visible
Spectrophotometer. The variables required for the computations with
the Lifshitz formula were derived from the absorbance data. The
Matlab software tools were used in the mathematical analysis of the
data produced from the experiments (absorbance values). The
Hamaker constants and the combined Hamaker coefficients were
obtained using the values of the dielectric constant together with the
Lifshitz Equation. The absolute combined Hamaker coefficients
A132abs and A131abs on both infected and uninfected sputum samples
gave the values of A132abs = 0.21631x10-21Joule for M-TB infected
sputum and Ã132abs = 0.18825x10-21Joule for M-TB/HIV infected
sputum. The significance of this result is the positive value of the
absolute combined Hamaker coefficient which suggests the existence
of net positive van der waals forces demonstrating an attraction
between the bacteria and the macrophage. This however, implies that
infection can occur. It was also shown that in the presence of HIV,
the interaction energy is reduced by 13% conforming adverse effects
observed in HIV patients suffering from tuberculosis.
Abstract: Electrostatic interaction energy (ΔEEDL) is a part of the Extended Derjaguin-Landau-Verwey-Overbeek (XDLVO) theory, which, together with van der Waals (ΔEVDW) and acid base (ΔEAB) interaction energies, has been extensively used to investigate the initial adhesion of bacteria to surfaces. Electrostatic or electrical double layer interaction energy is considerably affected by surface potential; however it cannot be determined experimentally and is usually replaced by zeta (ζ) potential via electrophoretic mobility. This paper focusses on the effect of ionic concentration as a function of pH and the effect of mineral grain size on ζ potential. It was found that both ionic strength and mineral grain size play a major role in determining the value of ζ potential for the adhesion of P. putida to hematite and quartz surfaces. Higher ζ potential values lead to higher electrostatic interaction energies and eventually to higher total XDLVO interaction energy resulting in bacterial repulsion.
Abstract: In the present study, the kinetics of thermal
degradation of a phenolic and lignin reinforced phenolic foams, and
the lignin used as reinforcement were studied and the activation
energies of their degradation processes were obtained by a DAEM
model. The average values for five heating rates of the mean
activation energies obtained were: 99.1, 128.2, and 144.0 kJ.mol-1 for
the phenolic foam; 109.5, 113.3, and 153.0 kJ.mol-1 for the lignin
reinforcement; and 82.1, 106.9, and 124.4 kJ.mol-1 for the lignin
reinforced phenolic foam. The standard deviation ranges calculated
for each sample were 1.27-8.85, 2.22-12.82, and 3.17-8.11 kJ.mol-1
for the phenolic foam, lignin and the reinforced foam, respectively.
The DAEM model showed low mean square errors (
Abstract: Using the first-principles full-potential linearized
augmented plane wave plus local orbital (FP-LAPW+lo) method
based on density functional theory (DFT), we have investigated the
electronic structure and magnetism of full Heusler alloys Co2ZrGe
and Co2NbB. These compounds are predicted to be half-metallic
ferromagnets (HMFs) with a total magnetic moment of 2.000 B per
formula unit, well consistent with the Slater-Pauling rule.
Calculations show that both the alloys have an indirect band gaps, in
the minority-spin channel of density of states (DOS), with values of
0.58 eV and 0.47 eV for Co2ZrGe and Co2NbB, respectively.
Analysis of the DOS and magnetic moments indicates that their
magnetism is mainly related to the d-d hybridization between the Co
and Zr (or Nb) atoms. The half-metallicity is found to be relatively
robust against volume changes. In addition, an atom inside molecule
AIM formalism and an electron localization function ELF were also
adopted to study the bonding properties of these compounds, building
a bridge between their electronic and bonding behavior.
As they have a good crystallographic compatibility with the lattice of
semiconductors used industrially and negative calculated cohesive
energies with considerable absolute values these two alloys could be
promising magnetic materials in the spintronic field.
Abstract: Evaluated nuclear decay data for the 217Po nuclide is
presented in the present work. These data include recommended
values for the half-life T1/2, α-, β-- and γ-ray emission energies and
probabilities. Decay data from 221Rn α and 217Bi β—decays are
presented. Q(α) has been updated based on the recent published work
of the Atomic Mass Evaluation AME2012. In addition, the logft
values were calculated using the Logft program from the ENSDF
evaluation package. Moreover, the total internal conversion electrons
and the K-shell to L-shell and L-shell to M-shell and to N-shell
conversion electrons ratios K/L, L/M and L/N have been calculated
using Bricc program. Meanwhile, recommendation values or the
multi-polarities have been assigned based on recently measurement
yield a better intensity balance at the 254 keV and 264 keV gamma
transitions.