Complementary Energies Research Articles

A new low-carbon project scheduling problem with renewable and traditional energy: A comprehensive analysis and its solution

Employing multi-energy complementarity in project energy supply proves to be an efficient strategy for accomplishing low-carbon project scheduling. However, current project scheduling problems primarily concentrate on traditional single-energy models. They optimize schedules to reduce energy emissions but often neglect the potential of renewable energy. This paper integrates project scheduling and renewable energy as interrelated aspects. Based on a renewable energy supply model grounded in the generation characteristics of renewable energy sources, a model for MC-MRCPSPM (multi-mode resource-constrained project scheduling problem with multiple complementary energies in the manufacturing context) is constructed and a memetic algorithm is employed for its resolution. The research findings conclusively demonstrate that using renewable energy as a power source during project execution leads to an average reduction of approximately 58.8% in carbon emissions, with a justifiable 14.73% increase in energy costs. Employing a multi-energy complementarity approach in project scheduling effectively reduces carbon emissions while maintaining reasonable energy costs and offers project managers greater decision-making flexibility.

Static, dynamic and buckling behavior of functionally graded beams with tunable inclusions

The introduction of microstructurally tunable materials endorses functionally graded (FG) beams with distinctly inspiring functionalities and mechanical properties. In order to facilitate the multiscale design of FG beams and evaluations of corresponding mechanical behavior, analytical solutions are developed in the present research on the static, dynamic and buckling responses of FG beams reinforced with graphene platelets, porosity or origami inclusions, etc. To facilitate the analytical derivation as well as numerical extension, this paper establishes a theoretical framework, firstly formulating the principle of virtual work and reciprocal theorem of work for the FG beams, and then deriving and proving the principles of minimum potential and complementary energies, the former of which is used for the establishment of the variational principles for the static bending, free vibration and buckling phenomenon in the present work. Following the proposed variational principles and considering Timoshenko beam theory, the strong-form partial differential governing equations as well as the corresponding boundary conditions can be obtained for static bending, free vibration and buckling responses of FG beams. The Ritz method is finally employed to obtain the explicit expressions of transverse bending and rotation as well as the frequencies and critical loads for FG beams with different boundary conditions. What’s more, it should be noted that the FG of the beams is achieved through tailoring micromechanical parameters, such as volume fraction and distribution of reinforcement, which are usually unevenly distributed. The mechanical responses of FG beams are also predicted through micromechanics approaches, such as Halpin-Tsai expression. Conventional GPL distributions as well as graphene origami (GOri) distributions with negative Poisson's ratios (NPR) are also presented to validate the analytical derivation and solutions. Finally, the proposed solutions are employed to investigate the effect of the microstructural parameters on the effective behavior of FG beams.

On variational principles in coupled strain-gradient elasticity

Strain-gradient elasticity is a special case of high-gradient theories in which the potential energy density depends on the first and second gradient of the displacement field. The presence of a coupling term in the material law leads to a non-diagonal quadratic form of the stored energy, which makes it difficult for the derivation of fundamental theorems. In this article, two variational principles of the minimum of potential and complementary energies are argued in the context of the coupled strain-gradient elasticity theory. The basis of the proofs of both variational principles is the equivalent transformation of the stain and strain-gradient energy density that allows to avoid the complication related to the presence of the fifth-rank coupling tensor in the equation for the potential energy density and leads to diagonalization of the quadratic form of the stored energy. This transformation enables to inverse Hook’s law, to determine compliance tensors, and to obtain closed-form relation for the complementary energy. After that the proofs of both principles of a minimum of potential and complementary energies are provided in the usual manner adopted in the classical theory of elasticity.

Textured HTM-free perovskite/PbS quantum dot solar cell: Optical and electrical efficiency improvement by light trapping control

In recent years, have been seen a leap at the opportunity of investigation tandem solar cells. This due to the complementary bandgap energies of various layers which leads to enhancement of the light absorption and the power conversion efficiency (PCE) of this type of solar cells. In this numerical based study, a new hole transport material (HTM) free perovskite/quantum dot solar cell, exploiting a finite element method (FEM), has been conducted for the first time. The series connection of perovskite (CH3NH3PbI3, 1.55 eV) and colloidal quantum dot (CQD) of lead sulphide (PbS-CQD, 1.3 eV) as light-carrier absorber layers is analysed to achieve the optimal performance with short-circuit current (Jsc) = 25.4 mA/cm2, open-circuit voltage (Voc) = 0.8 V, fill factor (FF) = 0.84. The simulation results illustrate that tandem solar cell yields an overall PCE of 17.2%, exceeding that of 14.53 % of bare perovskite absorbing layer in planar perovskite solar cell (PSC). To enhance the light absorption within the absorber layer and consequently to achieve a higher efficiency, pyramidal texturing of layers, as an effective light-management method was investigated and it reveals that the Jsc and PCE is increased to 29.3 mA/cm2 and 19.52% respectively. Comparing to the planar perovskite architecture, PCE is improved from 14.53% to 19.52%, indicating a great potential of nanostructure designing in tandem solar cells.

A constitutive model for materials with directionally strain locking microstructures

Strain locking materials have a limit to the extent to which they can be stretched along one or more axes. The strain limit can be due to the reorientation of stiffening phases at microstructural or molecular scales along the direction of the applied load. Both natural and manmade composites can exhibit such a response when initially wavy fibers or other corrugated structures gradually straighten and limit the extensibility of the material. A new constitutive model is developed for materials that exhibit strain locking along a preferred axis. The model assumes the microstructure is composed of linear elastic material with embedded zig-zag shaped fiber phase that is oriented along the preferred locking axis. The response is governed by a complementary energy density function which is partitioned into separate portions that represent the complementary energies within the fibers and the matrix respectively. A new, nonlinear form for the complementary energy density function of strain locking fibers is derived based on a relationship between the applied stress and the strain of the fiber. An example material that exhibits strain locking longitudinally but is transversely linear-elastic is considered. The behaviors of the example material under tension and compression along the longitudinal and transverse axis are illustrated. A comparison is made with FEM modeling of a strain locking microstructure explicitly fitting the constitutive model parameters with both FEM simulated and experimental data for real material.

Effective anti-plane moduli of couple stress composites containing elliptic multi-coated nano-fibers with interfacial damage and variational bounds

Prediction of the anti-plane moduli of solids consisting of a given distribution of unidirectionally aligned elliptic multi-coated fibers with interfacial damage is the focus of this paper. The fibers and their coating layers may be in the order of nano or micro scales. All the constituent phases of the composite are supposed to be described in terms of couple stress elasticity. Accordingly, the bounds for the overall shear moduli of the aforementioned composites are provided by employing the principles of minimum potential and complementary energies. Certain subtleties associated with the elliptic multi-coated fibers for three cases of pure sliding (completely damaged), imperfect (partially damaged), and perfect (undamaged) interface conditions will be discussed. The inherent anisotropy introduced due to the ellipse geometry of the fibers’ cross-sections is addressed. The effects of the ellipse aspect ratio as well as its size, interfacial damage, and rigidity on the effective anti-plane moduli of such composites will be examined.

Estimating the energy in current signals during electrical sounding: a novel approach

Despite the rapidity in the use of electrical sounding/expanding probe technique in the study of hydrology, mineralogy, contamination, and other geophysically based studies over decades, it appears that our ability to identify the relationships between the energy loaded in direct currents injected into the ground between two electrodes at low polarizing frequency is not yet realized and hence the drive for this research. This study is insightfully undertaken to address this problem by establishing the novel links associated with the existing geo-resistivity theories and the two complementary energies, the voltage-driven energy called charging energy and the charge-driven energy called the discharging energy. This was achieved by sorting the resistivity values realized from electrical sounding technique into regimes (trends of resistivities representing certain geologic layers) and plotting each regime in a location against the signal current low polarizing frequency measured from the relationship between power line frequency and the ratio of potential to current separations. The two energies, which are determinable from the slopes of regressed resistivity-period plots and the novel relations established in this work, depend on the dynamic parameters βv and βq, which are respectively called the voltage geometric index of energy and charge geometric index of energy. These indices connect earth resistivity to energy and frequency/relaxation period. Calculating the energy for each sounding at its polarizing frequency, the complementary charging and discharging energies were traced to be dependent on conductivity/resistivity of the geological sequence/regimes. The established equations, graphs, and contour maps give insightful and expanded information on the dependence of energy loaded on injected currents into the ground. The charging energy, which is enhanced in arenaceous layers, has low conductivity and is believed to have high permittivity and low energy loss factor, which is not determined in this work while discharging energy in argillites is high as conductivity and energy loss factor increase at decreasing permittivity. In all cases, the currents and its loaded energy are in comparatively minute magnitudes.

A finite strain non-parametric hyperelastic extension of the classical phenomenological theory for orthotropic compressible composites

The phenomenological linear theory of orthotropic compressible materials is employed systematically in the engineering and scientific analysis of a large scope of bulk and composite materials. However, at finite elastic strains, multiscale and fiber-based parametric models are typically employed, which material parameters are fitted to macroscopic experimental data using optimization procedures. Phenomenological extensions of the linear theory capable of effectively modelling such a large scope of materials are not available. What we present in this work is a simple extension of the linear theory to finite strains such that at every deformation level, the infinitesimal theory is fully recovered. The model is based in non-parametric spline complementary energies employing an energy decomposition compatible with the classical infinitesimal expression at all strain levels. No material parameter is explicitly involved because the spline-based stress energies are numerically computed (not fitted) directly from experimental data. We show the applicability of the model to capture (1) the behavior of orthotropic bimodulus materials consistent with hyperelasticity (a novel formulation also presented herein), (2) orthotropic auxetic foams, and (3) composites at finite strains.

A monolithic nanostructured-perovskite/silicon tandem solar cell: feasibility of light management through geometry and materials selection

The use of several layers of different materials, taking advantage of their complementary bandgap energies, improves the absorption in multi-junction solar cells. Unfortunately, the inherent efficiency increment of this strategy has a limitation: each interface introduces optical losses. In this paper, we study the effects of materials and geometry in the optical performance of a nanostructured hybrid perovskite – silicon tandem solar cell. Our proposed design increases the performance of both subcells by managing light towards the active layer, as well as by minimizing reflections losses in the interfaces. We sweep both refractive index and thickness of the transport layers and the dielectric spacer composing the metasurface, obtaining a range of these parameters for the proper operation of the device. Using these values, we obtain a reduction in the optical losses, in particular they are more than a 33% lower than those of a planar cell, mainly due to a reduction of the reflectivity in the device. This approach leads to an enhancement in the optical response, widens the possibilities for the manufacturers to use different materials, and allows wide geometrical tolerances.

Continuous fatigue damage prediction of a rubber fibre composite structure using multiaxial energy‐based approach

AbstractThis paper details an advanced method of continuous fatigue damage prediction of rubber fibre composite structures. A novel multiaxial energy‐based approach incorporating a mean stress correction is presented and also used to predict the fatigue life of a commercial vehicle air spring. The variations of elastic strain and complementary energies are joined to form the energy damage parameter. Material parameter α is introduced to adapt for any observed mean stress effect as well as being able to reproduce the well‐known Smith‐Watson‐Topper criterion. Since integration to calculate the energies is simplified, the approach can be employed regardless of the complexity of the thermo‐mechanical load history. Several numerical simulations and experimental tests were performed in order to obtain the required stress‐strain tensors and the corresponding fatigue lives, respectively. In simulations, the rubber material of the air spring was simulated as nonlinear elastic. The mean stress parameter α, which controls the influence of the mean stress on fatigue life, was adjusted with respect to those energy life curves obtained experimentally. The predicted fatigue life and the location of failure are in very good agreement with experimental observations.

Identification of Heterogeneous Elastoplastic Behaviors Using the Constitutive Equation Gap Method

Recent developments in imaging techniques now facilitate local field measurements (e.g. strain, temperature, etc.). In this study, we identify the spatial distribution of material properties and local stress fields using an inverse identification method based on the constitutive equation gap (CEG). The CEG concept is based both on minimization of a cost function equal to the sum of the potential and complementary energies, and on the deviation between the measured and computed strain fields. We propose a new approach for identifying heterogeneous property fields (mechanical parameters and stress) using a secant elastoplastic tensor and a measured strain field obtained by full-field measurement. The reliability of the method is checked using finite element simulation data as reference full-field measurements. The method is then applied on noisy displacement fields to assess its robustness. Finally, the developed inverse method is tested on real measured data.

Plate theory as the variational limit of the complementary energy functionals of inhomogeneous anisotropic linearly elastic bodies

We consider a sequence of linear hyper-elastic, inhomogeneous and fully anisotropic bodies in a reference configuration occupying a cylindrical region of height . We study, by means of Γ-convergence, the asymptotic behavior as goes to zero of the sequence of complementary energies. The limit functional is identified as a dual problem for a two-dimensional plate. Our approach gives a direct characterization of the convergence of the equilibrating stress fields.

Towards a complete characterization of the effective elasticity tensors of mixtures of an elastic phase and an almost rigid phase

The set $GU_f$ of possible effective elastic tensors of composites built from two materials with positive definite elasticity tensors $\BC_1$ and $\BC_2=\Gd\BC_0$ comprising the set $U=\{\BC_1,\Gd\BC_0\}$ and mixed in proportions $f$ and $1-f$ is partly characterized in the limit $\Gd\to\infty$. The material with tensor $\BC_2$ corresponds to a material which (for technical reasons) is almost rigid in the limit $\Gd\to \infty$. The paper, and the underlying microgeometries, have many aspects in common with the companion paper "On the possible effective elasticity tensors of 2-dimensional printed materials". The chief difference is that one has a different algebraic problem to solve: determining the subspaces of stress fields for which the thin walled structures can be rigid, rather than determining, as in the companion paper, the subspaces of strain fields for which the thin walled structure is compliant. Recalling that $GU_f$ is completely characterized through minimums of sums of energies, involving a set of applied strains, and complementary energies, involving a set of applied stresses, we provide descriptions of microgeometries that in appropriate limits achieve the minimums in many cases. In these cases the calculation of the minimum is reduced to a finite dimensional minimization problem that can be done numerically. Each microgeometry consists of a union of walls in appropriate directions, where the material in the wall is an appropriate $p$-mode material, that is almost rigid to $6-p\leq 5$ independent applied stresses, yet is compliant to any strain in the orthogonal space. Thus the walls, by themselves, can support stress with almost no deformation. The region outside the walls contains "Avellaneda material" that is a hierarchical laminate which minimizes an appropriate sum of elastic energies.

On the possible effective elasticity tensors of 2-dimensional and 3-dimensional printed materials

The set $GU_f$ of possible effective elastic tensors of composites built from two materials with elasticity tensors $\BC_1>0$ and $\BC_2=0$ comprising the set $U=\{\BC_1,\BC_2\}$ and mixed in proportions $f$ and $1-f$ is partly characterized. The material with tensor $\BC_2=0$ corresponds to a material which is void. (For technical reasons $\BC_2$ is actually taken to be nonzero and we take the limit $\BC_2\to 0$). Specifically, recalling that $GU_f$ is completely characterized through minimums of sums of energies, involving a set of applied strains, and complementary energies, involving a set of applied stresses, we provide descriptions of microgeometries that in appropriate limits achieve the minimums in many cases. In these cases the calculation of the minimum is reduced to a finite dimensional minimization problem that can be done numerically. Each microgeometry consists of a union of walls in appropriate directions, where the material in the wall is an appropriate $p$-mode material, that is easily compliant to $p\leq 5$ independent applied strains, yet supports any stress in the orthogonal space. Thus the material can easily slip in certain directions along the walls. The region outside the walls contains "complementary Avellaneda material" which is a hierarchical laminate which minimizes the sum of complementary energies.

The Importance of a Male Presence in College Counseling

The Taoist concept of yin and yang asserts that in order to have a healthy equilibrium in society, as in nature, integration must be achieved between two complementary and interdependent energies. ...

Effects of conjugated polymer incorporation on the morphology and energy harvesting of solution-processed, phthalocyanine-based thin films

Here, we investigate the morphology, spectral absorption bandwidth and energy transfer in solution-processed, phthalocyanine-based thin films blended with conjugated polymer materials with complementary absorption bands. Unary, binary, and ternary solutions of the solution- processable phthalocyanine derivative 2,3,9,10,16,17,23,24-octakis(octyloxy)-29H,31H-phthalocyanine (Oct-Pc) and the conjugated polymers poly(9,9-dioctylfluorenyl-2,7-diyl) (PFO) and poly(3-hexylthiophene) (P3HT) were used to prepare sub-55-nm-thick unary-phase and blended thin films. Spectroscopic analysis shows that absorption band full-width-at-half-maximum (FWHM) values increase from between 60nm and 160nm for the individual materials to greater than 450nm for the composite ternary-blend thin film due to the complementary bandgap energies and spectral absorption bands of the constituent materials. Additionally, photoluminescence and transient absorption measurements show very efficient transfer of excited-state energy in the wider band-gap materials (donors) to the narrower band-gap material (acceptor). Resonant energy or charge transfer occurs with efficiencies between 90% and 100% for the various blends. Atomic-force microscopy and grazing-incidence, wide-angle X-ray scattering data indicate that P3HT and Oct-Pc exhibit the poorest blending. This correlates with the lowest donor photoluminescence quenching efficiency due to the extended separation of the P3HT chains from Oct-Pc molecules. However, addition of a relatively small fraction of PFO disrupts Oct-Pc crystallinity and enables improved mixing and energy transfer between P3HT and Oct-Pc.

Fatigue life prediction using multiaxial energy calculations with the mean stress effect to predict failure of linear and nonlinear elastic solids

An approach is presented that enables the calculation of elastic strain energy in linear and nonlinear elastic solids during arbitrary thermomechanical load cycles. The approach uses the simple fact that the variation of both strain and complementary energies always forms a rectangular shape in stress–strain space, hence integration is no longer required to calculate the energy. Furthermore, the approach considers the mean stress effect so that predictions of fatigue damage are more realistically representative of real-life experimental observations. By doing so, a parameter has been proposed to adjust the mean stress effect. This parameter α is based on the well-known Smith–Watson–Topper energy criterion, but allows consideration of other arbitrary mean stress effects, e.g. the Bergmann type criterion.The approach has then been incorporated into a numerical method which can be applied to uniaxial and multiaxial, proportional and non-proportional loadings to predict fatigue damage. The end result of the method is the cyclic evolution of accumulated damage. Numerical examples show how the method presented in this paper could be applied to a nonlinear elastic material.

Capacity allocation of hybrid solar-wind energy system based on discrete probabilistic method

Complementary renewable energies like wind and solar power may be more sufficient to satisfy reliability requirements. This paper proposes a quantitative capacity allocation method of a hybrid wind and solar energy system. First, discrete probability distributions are established to model the random factors including the volatility of power outputs and the failure of components. Then a multiobjective optimization model is formulated with objectives of minimization of the total investment, the nodal voltages violating limits probability, and power supply inadequacy probability. For the purpose of fast probability computing with a satisfactory precision degree, an innovative probabilistic load flow algorithm is introduced, which deals with means and increments of random variables separately and uses cumulants as well as Gram--Charlier series to obtain probabilistic distributions of state variables. A modified parallel elitist nondominated sorting genetic algorithm II is used to search the Pareto optimal configuration solutions.

Calcium micro-depositions in jugular truncular venous malformations revealed by Synchrotron-based XRF imaging

It has been recently demonstrated that the internal jugular vein may exhibit abnormalities classified as truncular venous malformations (TVMs). The investigation of possible morphological and biochemical anomalies at jugular tissue level could help to better understand the link between brain venous drainage and neurodegenerative disorders, recently found associated with jugular TVMs. To this end we performed sequential X-ray Fluorescence (XRF) analyses on jugular tissue samples from two TVM patients and two control subjects, using complementary energies at three different synchrotrons. This investigation, coupled with conventional histological analyses, revealed anomalous micro-formations in the pathological tissues and allowed the determination of their elemental composition. Rapid XRF analyses on large tissue areas at 12.74 keV showed an increased Ca presence in the pathological samples, mainly localized in tunica adventitia microvessels. Investigations at lower energy demonstrated that the high Ca level corresponded to micro-calcifications, also containing P and Mg. We suggest that advanced synchrotron XRF micro-spectroscopy is an important analytical tool in revealing biochemical changes, which cannot be accessed by conventional investigations. Further research on a larger number of samples is needed to understand the pathogenic significance of Ca micro-depositions detected on the intramural vessels of vein walls affected by TVMs.

Homogenization of quadratic complementary energies: a duality example

We study an example in two dimensions of a sequence of quadratic functionals whose limit energy density, in the sense of $\Gamma $-convergence, may be characterized as the dual function of the limit energy density of the sequence of their dual functionals. In this special case, $\Gamma $-convergence is indeed stable under the dual operator. If we perturb such quadratic functionals with linear terms this statement is no longer true.