Energetic Solutions Research Articles

Combustion behavior of NMP-001, a nitromethane-based green rocket propellant

Hydrazine’s carcinogenic and toxic nature makes its use in space propulsion expensive and necessitates careful launch campaign planning, which may cause delays. One already established alternative is to use energetic salt-based ionic solution propellants. However, the costs remain high because these salts are costly and highly regulated energetic materials. Additionally, propellants based on these energetic salts produce much higher temperatures during decomposition and combustion, as is the case for hydrazine. Consequently, expensive refractory metal-based alloys and high-temperature oxidation-resistant catalytic reactors must be used, which further drives up the costs. Alternatively, hydrogen peroxide may be used, though only in applications with a low specific impulse requirement. This study explores an alternative approach: using nitromethane, a commonly available laboratory solvent. NMP-001 is a nitromethane-based monopropellant that contains additives that allow for low-pressure combustion and reduce sensitivity to mechanical stimuli. Multiple combustion chamber configurations with varying characteristic lengths were tested in rocket combustion experiments. With the 11.5 m L∗-configuration, a 15.1 bar low-pressure limit could be determined. The 7.3 and 5.0 m L∗-configurations yielded a 16.2 and 28.3 bar low-pressure combustion limits, respectively. These outcomes are significantly below the 30 bar limit reported in the literature. Despite using only a simple heat-sink combustion chamber with a non-sophisticated injector element and a non-optimized propellant formulation, combustion was 83 to 95 % efficient with a C* ranged between 1133 to 1302 m/s. These figures are higher than for hydrogen peroxide and are comparable to the theoretical performance of state-of-the-art green liquid monopropellants.

DETERMINATION OF THE BIOMETHANE POTENTIAL OF DIFFERENT TYPES OF MANURE FROM EXTENSIVE ANIMAL FARMING

Livestock production is a potential environmental pollutan because of the high concentartions of animals on the small area. Production of biogas with anaerobic degradation from organic waste is one of the pledge alternative energetic solutions, especially from organic manure made from animal farming and other residuals of agricultural production.The aim of this paper was to determine posibillity of using manure different origin from extensive animal breeding for production of biogas in labaratory conditions. The results obtained will be based on posibillity of use waste streams from extensive animal husbandry as basic substrate for anaerobic digestion.In this regard, cosubstrates were formed as mixture 1 chicken excrement; mixture 2 sheep manure; mixture 3 cow manure; all three basic substrates were in mixture with the sludge from the wastewater treatment plant. The results showed production of 71,5 ml CH4/gVS for mixture 1, 68,65 ml CH4/gVS for mixture 2 and 48,68 ml CH4/gVS for mixture 3. KEYWORDS:extensive breeding, manure, anaerobic digestion, biogas, biomethane potentional

The possibility of tachyons as soliton solutions in [formula omitted] dimensions via [formula omitted]-field models

Tachyons or hypothetical faster-than-light (FTL) particles would fail the principle of causality. Such particles may only be imagined when they have no energy and momentum and, thus, no observable interaction. In this paper, we show that the classical relativistic field theory with non-standard Lagrangian densities (k-field models) does not rule out the existence of FTL particle-like solutions (solitons) with zero energy and momentum in 3+1 dimensions. However, contrary to our expectation, we show that it is possible to have k-field models that lead to energetic FTL soliton solutions in 3+1 dimensions.

Evidence of nonlinearity tailoring in static and dynamic responses of honeycomb and auxetic hourglass lattice metastructures

Nature’s morphology and optimal energetic solutions remain the key motivation for designing cellular-based lattice structures. Understanding the nonlinear dynamical behaviors that arise from different lattice topologies of such structures in the metastructure framework is crucial for their successful implementation in various novel designs and technologies related to vibration and shape control. This paper presents a study of the static and dynamic response of auxetic and honeycomb lattices with hourglass or dome-shaped metastructures. The potential tailoring of nonlinearity of such responses through various design parameters that play a vital role in shaping the dynamic properties of such structures is discussed here. The impact of cell design parameters on the resulting macroscopic behavior is assessed using both numerical simulations and experimental studies. The transition from softening to hardening nonlinear dynamic responses is reported with cell topologies ranging from the regular honeycomb to auxetic topologies that are widely used as fundamental cells of cellular materials design. The experimental study is based on the time responses measured to verify the numerical predictions. The experimental system consists of different 3D printed hourglass samples based on the auxetic and honeycomb lattices on which dynamic testing using a laser Doppler vibrometer is performed. The design strategies proposed in this paper can be integrated into a wide range of lattice-based materials for noise and vibration control applications and biomedical devices.

Energetic solutions to rate-independent large-strain elasto-plastic evolutions driven by discrete dislocation flow

This work rigorously implements a recent model of large-strain elasto-plastic evolution in single crystals where the plastic flow is driven by the movement of discrete dislocation lines. The model is geometrically and elastically nonlinear, that is, the total deformation gradient splits multiplicatively into elastic and plastic parts, and the elastic energy density is polyconvex. There are two internal variables: The system of all dislocations is modeled via one-dimensional boundaryless integral currents, whereas the history of plastic flow is encoded in a plastic distortion matrix-field. As our main result, we construct an energetic solution in the case of a rate-independent flow rule. Besides the classical stability and energy balance conditions, our notion of solution also accounts for the movement of dislocations and the resulting plastic flow. Because of the path-dependence of plastic flow, a central role is played by so-called “slip trajectories”, that is, the surfaces traced out by moving dislocations, which we represent as integral 2-currents in space-time. The proof of our main existence result further crucially rests on careful a priori estimates via a nonlinear Gronwall-type lemma and a rescaling of time. In particular, we have to account for the fact that the plastic flow may cause the coercivity of the elastic energy functional to decay along the evolution, and hence the solution may blow up in finite time.

AUTONOMOUS MOBILE ROBOT WITH HYBRID PEM FUEL-CELL AND ULTRACAPACITORS ENERGY SYSTEM. DEDALO 2.0

This paper presents a hybrid configuration combining a hydrogen fuel cell and ultracapacitors to create an energy storage system. Hybrid topology is constructed using a SEPIC converter, which connects the fuel cell with the DC bus whereas a bidirectional Buck-Boost converter links the ultracapacitors group with the DC bus. The main aim is to increase the efficiency of the hybrid power system applied about an autonomous mobile robot. An active Fuel Cell voltage control strategy is presented to manage the power flows. In addition, the overall efficiency of the proposed hybrid power system at overload operation is higher than the conventional one. In this paper, an autonomous mobile robot was converted from a conventional lead-acid or lithium-ion battery to a hybrid PEM Fuel-Cell and ultracapacitors as the power source. The integration of UCaps as element of energy storage on the robot was studied with the aim to improve the energetic solution

ULISES: AUTONOMOUS MOBILE ROBOT USING ULTRACAPACITORS-STORAGE ENERGY SYSTEM.

Recent technology improvements enabled ultracapacitors (UCaps) to be an interesting option for short-term power applications, such as in industry, automotive and traction drives, regenerative energy system, telecommunication and medical equipment. UCaps are being developed as an alternative to pulse batteries. To be an attractive alternative, ultracapacitors must have at least one order of magnitude higher power and a much longer shelf and cycle life than batteries. UCaps have much lower energy density than batteries and their low energy density is, in most cases, the factor that determines the feasibility of their use in a particular power application. The main advantages of UCaps are that they can provide high power capability (60-120s is typical), excellent reversibility (90-95% or higher) and long cycle life (>105 cycles). Thus they exhibit 20-200times larger capacitance per unit volume or mass than conventional capacitors. In this paper, an autonomous mobile robot was converted from a conventional lead-acid or lithium-ion battery to an ultracapacitors as the power source. The integration of UCaps as element of energy storage on the robot was studied with the main of optimizing the energetic solution. The design of the ultracapacitors based power supply system is outlined.

A potential coupling of reforming and electrolysis for producing renewable hydrogen from landfill gas

Organic sold waste disposed of in landfills undergoes a mostly anaerobic process which generates a mixture of methane (CH4), carbon dioxide (CO2) and other various gases such as nitrogen, oxygen, sulphides, and non-methane organic compounds (NMOC), known as landfill gas (LFG). Being composed mostly of CH4 and CO2, landfill gas is a potent greenhouse gas (GHG). As a result, various waste treatment interventions are required to minimize the potential catastrophic damage to the environment from direct greenhouse gas emissions from landfills. One effective solution is combustion to generate electricity exploiting methane’s flammability properties. Biomass-based power plants have been present for decades. However, the combustion process is accompanied by a remarkable production of thermal energy which is typically not exploited and therefore lost to the ambient. The current work presents an energetic solution to manage organic waste by employing green hydrogen production. To do so, a hybrid layout based on a cogeneration unit (CHP) fed with landfill gas is considered. The electrical power produced by the CHP is used to produce hydrogen through low-temperature water electrolysis. Furthermore, due to the significant waste heat available in the system, excess thermal power is employed for the methane steam reforming process through a heat recovery section. Hydrogen produced from the reforming section is green since the input is from landfill gas, which is considered renewable. The levelized cost of hydrogen produced from such a hybrid layout is obtained and compared with non-renewable sources in this field. In addition, the annual H2 production rate is calculated for a capacity factor equal to 70%. The results show an annual Hydrogen production of about 167 t/y. LCOH at the stack of about 2 €/kg is reported.

Energy optimization of an electrical supply network by the integration of renewable source Case study: ADE - Adrar

This research lies within the scope of environmental research for seeking solutions for the optimizations of energy in the electrical supply network ADE- Adrar (Algérienne des Eaux d’Adrar/Algeria). Indeed, the principal aiming of this research is the integration of renewable resources (energy independence and sustainable development) that it pushes us to consider from now on the energy problem not only according to the economic point of view, but also according to an ecological point of view (reduction of CO2 emission). This with us encouraged to develop our systems of energy on the basis of distributed generation on a large scale including/understanding renewable energy and the high-output energetic solutions.

Energetic evolutions for linearly elastic plates with cohesive slip

A quasistatic model for a horizontally loaded thin elastic composite at small strains is studied. The composite consists of two adjacent plates whose interface behaves in a cohesive fashion with respect to the slip of the two layers. We allow for different loading–unloading regimes, distinguished by the presence of an irreversible variable describing the maximal slip reached during the evolution. Existence of energetic solutions, characterized by equilibrium conditions together with energy balance, is proved by means of a suitable version of the Minimizing Movements scheme. A crucial tool to achieve compactness of the irreversible variable are uniform estimates in Hölder spaces, obtained through the regularity theory for elliptic systems. The case in which the two plates may undergo a damage process is also considered.

Peculiarities of structural, electrokinetic, energetic, and magnetic properties semiconductive solid solution Lu1-xVxNiSb

The structural, electrokinetic, energetic, and magnetic properties of the new semiconductive solid solution Lu1-xVxNiSb, х=0–0.10, were studied. It was shown that V atoms could simultaneously occupy different crystallographic positions in different ratios, generating structural defects of acceptor and donor nature. This creates corresponding acceptor and donor bands in the bandgap εg of Lu1-xVxNiSb. The mechanism of the formation of two acceptor bands with different depths of occurrence has been established: a small acceptor band εА2, formed by defects due to the substitution of Ni atoms by V ones in the 4c position, and band εА1, generated by vacancies in the LuNiSb structure. The ratio of the concentrations of generated defects determines the position of the Fermi level εF and the conduction mechanisms. The investigated solid solution Lu1-xVxNiSb is a promising thermoelectric material.

Elastoplastic Deformations of Layered Structures

We formulate a large-strain model of single-slip crystal elastoplasticity in the framework of energetic solutions. The numerical performance of the model is compared with laboratory experiments on the compression of a stack of papers.

Existence results in large-strain magnetoelasticity

We investigate variational problems in large-strain magnetoelasticity, in both the static and the quasistatic settings. The model contemplates a mixed Eulerian–Lagrangian formulation: while deformations are defined on the reference configuration, magnetizations are defined on the deformed set in the actual space. In the static setting, we establish the existence of minimizers. In particular, we provide a compactness result for sequences of admissible states with equi-bounded energies which gives the convergence of the composition of magnetizations with deformations. In the quasistatic setting, we consider a notion of dissipation which is frame-indifferent and we show that the incremental minimization problem is solvable. Then we propose a regularization of the model in the spirit of gradient polyconvexity and we prove the existence of energetic solutions for the regularized model.

Assessment of Integrated Solutions for the Combined Energy Efficiency Improvement and Seismic Strengthening of Existing URM Buildings

The European building stock is an aging infrastructure, mainly built prior to building codes. Furthermore, 65% of these buildings are located in seismic regions, which need to be both energetic and seismically retrofitted to comply with performance targets. Given this, this manuscript presents integrated constructive solutions that combine both energy efficiency improvement and seismic strengthening. The goal and novelty is to design and to evaluate one-shot, compatible, noninvasive, and complementary solutions applied to the façades of buildings with a minimum cost. To do so, different constraints have been borne in mind: the urban environment, achievable seismic and energy performance targets, and reduced construction costs. The method was applied to an old Spanish neighbourhood constructed in the 1960s. Different retrofitting packages were proposed for an unreinforced masonry case study building. A sensitivity analysis was performed to assess the effects of each configuration. A benefit/cost ratio was proposed to comparatively assess and to rank the solutions. The results of the seismoenergetic performance assessment showed that improving the behaviour of walls leads to higher benefit ratios than improving the openings. However, this latter strategy generates much lower construction costs. Integrating seismic into energetic retrofitting solutions supposes negligible additional costs but can improve the seismic behaviour of buildings by up to 240%. The optimal solution was the addition of higher ratios of steel grids and intermediate profiles in openings while adding thermal insulation in walls and renovating the window frames with PVC and standard 4/6/4 double glazing.

Energetic solutions for the coupling of associative plasticity with damage in geomaterials

We prove existence of globally stable quasistatic evolutions, referred to as energetic solutions, for a model proposed by Marigo and Kazymyrenko in 2019. The behaviour of geomaterials under compression is studied through the coupling of Drucker–Prager plasticity model with a damage term tuning kinematical hardening. This provides a new approach to the modelling of geomaterials, for which non associative plasticity is usually employed. The kinematical hardening is null where the damage is complete, so there the behaviour is perfectly plastic. We analyse the model combining tools from the theory of capacity and from the treatment of linearly elastic materials with cracks.

Constructed p-2D/n-2D BiOCl/BiVO4 Nanoheterostructure for Photocatalytic Antibacterial Activity

Degradation of harmful organic pollutants using semiconductor materials has been represented as one of the energetic solution for wastewater treatment. A novel visible light photocatalyst of BiOCl/BiVO4 (BCl-BV) with a p-n heterojunction structure catalyst were synthesized using a simple hydrothermal method. Specifically, 1 g of BiOCl (BCL) powder was added to 100 mL of DW, followed by using drop casting of Bi(NO3)3 and Na2VO4 at various concentrations (0.25, 0.5, 0.75, and 1 mM). The structural and physical properties of synthesized materials are investigated by X-Ray Diffraction, FESEM measurement, EDS analysis and UV-Visible spectroscopy. Under visible-light irradiation, the photocatalytic activity of of synthesized materials were evaluated for the degradation of rhodamine (RhB), methylene orange (MO), and methylene blue (MB) concentrations. In comparison to pure BiOCl and BiVO4, the heterojunction significantly improved photodegradation efficiency for rhodamine (RhB), methylene orange (MO), and methylene blue (MB) under visible-light irradiation (> 400 nm). This is attributed to the B type heterojunction structure with a strong oxidative ability and efficient charge separation and transfer across the BiOCl/BiVO4 interface. Finally, the antibacterial activity of BiOCl, BiVO4,, and BiOCl/BiVO4 heterojunction was improved and reveal the strong interaction of BiVO4 and heterojunction BiOCl/BiVO4 with the bacterial membrane and higher generation of ROS through strong oxides like activity.

Energy Consumption Improvement of a Healthcare Monitoring System: Application to LoRaWAN

Recent advances in wireless communication technologies are having a great impact on people’s life, especially in the field of healthcare industry that provides a remote monitoring enabling medical staff to follow up the patient and diagnose his disease. LoRa wireless technology is becoming one of the most energetic effective solutions for Wireless Body Area Networks (WBANs) communications. In this work, we propose a LoRa-based low power healthcare WBAN platform called <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">HeaLoRa</i> for an adaptive patient monitoring process. Physicians can remotely monitor patient’s temperature, oxygen saturation level, blood pressure and heart rate to prevent any abnormality. Moreover, data acquisition and transmission are controlled based on a power consumption optimization strategy aiming to reduce redundant data. Based on the Early Warning Score (EWS), the system configuration is dynamically adapted, using a Fuzzy logic controller that makes the decision about the system sleep mode duration and the sent data rate. Furthermore, an analytical model of the energy consumption for acknowledged LoRa transmission is presented in this paper. The graphical abstract of the paper illustrates a medical application of a wireless body area network system where LoRa technology is used to transmit the data to a gateway then the data is transmitted to the doctor using IP based technology. By comparing with a reference system, the simulation results indicate that our system consumes 3 to 10 times less of energy depending on the studied scenario.

Elastoplasticity of gradient-polyconvex materials

We propose a model for rate-independent evolution in elastoplastic materials under external loading, which allows large strains. In the setting of strain-gradient plasticity with multiplicative decomposition of the deformation gradient, we prove the existence of the so-called energetic solution. The stored energy density function is assumed to depend on gradients of minors of the deformation gradient which makes our results applicable to shape-memory materials, for instance.

A vanishing-inertia analysis for finite-dimensional rate-independent systems with nonautonomous dissipation and an application to soft crawlers

We study the approximation of quasistatic evolutions, formulated as abstract finite-dimensional rate-independent systems, via a vanishing-inertia asymptotic analysis of dynamic evolutions. We prove the uniform convergence of dynamical solutions to the quasistatic one, employing the concept of energetic solution. Motivated by applications in soft locomotion, we allow time-dependence of the dissipation potential, and translation invariance of the potential energy.

Relating a Rate-Independent System and a Gradient System for the Case of One-Homogeneous Potentials

We consider a non-negative and one-homogeneous energy functional {{mathcal {J}}} on a Hilbert space. The paper provides an exact relation between the solutions of the associated gradient-flow equations and the energetic solutions generated via the rate-independent system given in terms of the time-dependent functional {{mathcal {E}}}(t,u)= t {{mathcal {J}}}(u) and the norm as a dissipation distance. The relation between the two flows is given via a solution-dependent reparametrization of time that can be guessed from the homogeneities of energy and dissipations in the two equations. We provide several examples including the total-variation flow and show that equivalence of the two systems through a solution dependent reparametrization of the time. Making the relation mathematically rigorous includes a careful analysis of the jumps in energetic solutions which correspond to constant-speed intervals for the solutions of the gradient-flow equation. As a major result we obtain a non-trivial existence and uniqueness result for the energetic rate-independent system.