Minimum Energy Input Research Articles

Degree of controllability for linear unstable systems

The degree of controllability is a measure to check how controllable a given system is, which makes up for the weak points of traditional methods for checking controllability. There are many definitions of the degree of controllability, and the most widely used measure is represented by controllability Gramian. This measure has physical meaning of minimum input energy to change the states. However, it is hard to use this method for unstable systems because the steady-state value of Gramian cannot be defined. Therefore, the degree of controllability for unstable systems is proposed in this paper. The definition of the measure is minimum control input energy to change the state from an arbitrary initial condition to an arbitrary final condition. The derivation result shows that the measure is the sum of two terms, one represented by Gramian of a stable subsystem and the other represented by Gramian of a subsystem that has mirror image poles of an anti-stable subsystem. These Gramians can be obtained by solving two Lyapunov equations. A simple numerical example shows the usefulness of the proposed measure of degree of controllability.

Sugarcane biorefineries: Case studies applied to the Brazilian sugar–alcohol industry

The use of biomasses is becoming increasingly appealing alternative, to give an partial solution lack of energy, with an ecofriendly approach, having on sugarcane a solid fundament; that receives the new and valuable complement of the innovative concept of the biorefineries it is productive installations, that can be summarized as to reach the higher overall yield from the raw materials, with the lowest environmental impact, at minimum energy input and giving the maximum of the energy output. The biorefinery is the true valuable option of a wide diversification, with by-products like the single cell protein and biogas from the distillery vinasse, new oxidants like methanol, second generation biofuels, biobutanol, etc.In this context this paper presents a study of five different configurations of biorefineries. Each case study being a system based on an autonomous distillery or sugar mill with an annexed distillery and coproduction of methanol from bagasse. The paper includes the use of sugarcane harvest residues (mainly straw) and a BIG–GT plant (Biomass Integrated Gasification–Gas Turbine) as alternatives to fulfill the energy demands of the complex.

THE INFLUENCE OF SIZE FRACTION ON THE COMPRESSIBILITY OF PINE SAWDUST AND THE EFFECTIVENESS CRITERION FOR DENSIFICATION

Particulate matter from biomass, e.g. wood sawdust, is very diverse. The basic parameter describing the densification process of particulate matter is its compressibility, quantified by the coefficient of compressibility. Knowing this coefficient for a specific material is a basic prerequisite for the application of compressibility equations describing the densification process, and for calculating the workload in the production process of high-grade solid biofuel. This paper deals with a methodology for determining the compressibility factor for sawdust on the basis of experiments to quantify pine sawdust. The experiments were performed in two stages. The first stage was an experimental investigation of the influence of size fraction on the final compressibility of pine sawdust. The results show the behaviour of the pressure load when the parameters of the particulate matter are changed. In the second stage, the experiments are evaluated and optimized to achieve minimum energy input of the process and a maximum degree of densification. The research results will be used to develop new technologies and machinery for biomass densification to achieve a high-grade solid biofuel.

Towards a Framework for Discussing and Assessing CO2 Utilisation in a Climate Context

Abstract This paper aims to place discussions about CO 2 utilisation onto a more secure foundation from the perspective of climate change mitigation. A conceptual framework is proposed that comprises three criteria for evaluating CO 2 utilisation options from the viewpoint of emission reduction potential. This framework places life cycle analysis at its forefront. Examples of emissions benefits for thermodynamic minimum energy inputs and possible real-world conditions are used to show that not all CO 2 utilisation is equally beneficial from a climate perspective. Most current and potential uses of CO 2 do not appear to yet satisfy the three main criteria of emission reduction benefits, revenue to cover CO 2 feedstock costs and meaningful scale. The notable exceptions are certain (geographically limited) approaches to enhanced oil recovery (CO2-EOR). Due to the energy required to convert CO 2 to useful products it appears highly likely that reducing CO 2 emissions through CO 2 utilisation will only be possible if the electricity (and, in some cases, the thermal energy) inputs are from renewable sources. This raises questions about the most appropriate use of renewable resources, especially if they are to be employed for the purpose of partially mitigating emissions from large stationary fossil fuel combustion plants. It also raises questions about how to match the potential revenue from and scale of CO 2 utilisation based on variable renewable resources with investments in CO 2 capture at meaningful scales. CO 2 utilisation options that can proceed without a CO 2 capture and purification step or can be located in regions where CCS is an ongoing commercial business may offer good opportunities for further development if they can scale to multi-million tonne per year activities. Climate policies that aim to support revenues for CO 2 utilisation activities will need to carefully consider how the fossil fuel value chain allocates liability for environmental damages associated with life cycle emissions; these are likely to be greater than zero but not accurately predictable.

Energy-saving trajectory planning for a toggle mechanism driven by a PMSM

In this paper, energy-saving trajectories are planned for a toggle mechanism driven by a permanent magnet synchronous motor (PMSM). The point-to-point (PTP) trajectory is described by a high-degree polynomial, which satisfies the end conditions of displacement, velocity, acceleration and jerk at the initial and final times. The real-coded genetic algorithm (RGA) method is employed to obtain the mechatronic system’s parameters, and to determine the coefficients of the polynomial, and its fitness function is the inverse of various input energies. The numerical simulations and experiments are compared among several degrees’ polynomials during the whole operation motion. Finally, it is found that the input absolute electrical energy (IAEE) occurs when the highest-degree polynomial is chosen. From the percentage of relative error with respect to the absolute input energy of a 7-degree polynomial, it is found that the percentage of relative error achieves 32% as the degree is 24 with enough for minimum input energy degree. The proposed methodology described in this research has the contribution. It can be applied to any mechatronic system which is required to design a minimum-energy point to point trajectory.

Trajectory planning based on minimum absolute input energy for an LCD glass-handling robot

The main idea of this paper is to design a novel point-to-point (PTP) trajectory based on minimum absolute input energy (MAIE) for an LCD glass-handing robot, which is driven by a permanent magnet synchronous motor (PMSM). The mechatronic system is described by a mathematical model of electrical and mechanical coupling equations. To generate the MAIE PTP trajectory, we employ a high-degree polynomial and compare with the trapezoidal, cycloidal and zero-jerk trajectories for various constraint conditions, which satisfy their corresponding desired constraints of angular displacement, speed, acceleration and jerk at the start and end times. The real-coded genetic algorithm (RGA) is used to search for the coefficients of high-degree polynomials for the PTP trajectories, and the inverse of absolute input electrical energy is adopted as a fitness function. From numerical simulations, it is found that either increasing the degree number of polynomials or decreasing the constraints at the start and end times will decrease the absolute input electrical energy. The proposed methodology for designing the MAIE PTP trajectory can also be applied to any mechatronic system driven by a PMSM.

A comparison of the energy consumption of rainfed durum wheat under different management scenarios in southern Italy

An energy consumption analysis comparing 12 management scenarios of durum wheat grown in southern Italy was carried out in order to identify the most energy efficient system with regard to productivity.The results showed that yield parameters were significantly affected by the tillage system and revealed that conservation tillage entailed the fewest field operations and lowest energy requirements with higher yield.Nitrogen rates had slight effects on yield parameters, whereas a linear relationship was found between increasing energy input and increasing nitrogen fertilizer. The highest proportion of energy input came from diesel fuel, followed by nitrogen fertilizer.Total input energy used per hectare increased with the increase in management intensity. However, per 1 kg of grain, energy intensity was directly linked to grain yield. The lowest average of 1.8 MJ kg−1 was for conservation tillage, followed by intensive tillage with 2.9 MJ kg−1, whereas reduced tillage was the most energy intense with 3.1 MJ kg−1.Conservation tillage of durum wheat in southern Italy can be used to maintain or increase productivity with only a minimum energy input.

Minimum Input Energy Trajectory Design of the Mechatronic Elevator System

The mechatronic elevator system driven by a permanent magnet synchronous motor (PMSM) is modeled by both the mechanical and electrical equations. The dimensionless forms are also derived for the purpose of practicable movements. In this paper, the minimum-input energy trajectory (MIET) and minimum control effort trajectory (MCET) based on Hamiltonian function and the five-degree (5-D) normalized polynomial trajectory are designed and compared. From the numerical simulations comparisons; it is found that the MIET has the minimum input absolute electrical energy (IAEE).

Acetylene Ignition Process in Combustion Thermal Spray

The acetylene ignition process in combustion thermal spray is typical of a laminar diffusion jet. It has all the features of a free jet. The aim of this research is to obtain the detail sparking ignition evolution process and the chemical reaction time scale and calculate the critical radius and minimum energy input required to produce a self-propagating flame in an acetylene fuel jet. Experiments are carried out by using a unique high-speed continuous CCD camera. The results show that the full sparking ignition time needs about 8 ms and this time scale can be used in the calculation of the flame flow fields in the combustion thermal spray jet.

Experimental Investigations on a Layer of HMX Explosive Crystals in Response to Drop-Weight Impact

Drop-weight experiments are performed on a thin layer of cyclotetramethylene tetranitramine (HMX) explosive crystals. The drop-weight impact machine is equipped with high-speed photographic systems. Experimental results show the effects of drop heights, mass of particles, and distributed density on compaction, deformation, transparency, reaction violence, and burning propagation. The aim is to establish a link between mechanical and thermal responses for a single layer of granular explosives. Minimum input energy and adequate number of particles, as well as sufficient mutual interactions among particles in the granular explosive sample, are necessary prerequisites for hot spot ignition and growth to burning. The course of the response, instead of a simple “go” or “no go” criterion is emphasized as a critical consideration in ranking material sensitivity.

Optimal capacity design of eccentrically braced steel frameworks using nonlinear response history analysis

Presented in this paper is an optimal capacity design method for steel building frameworks by adopting a nonlinear response history analysis procedure as the evolution tool for the structures under extreme earthquake loading. Minimum structural weight, minimum seismic input energy, and maximum hysteretic energy of fuse members are identified as design objectives. The design constraints include plastic deformation limit on every frame member and total deformation limit on each inter-story drift. The design optimization method employs a multi-objective genetic algorithm to search for optimal member section sizes from among commercially available steel section shapes. The design method is illustrated in details for a three-story eccentrically-braced steel frame.

Minimum energy desynchronizing control for coupled neurons

We employ optimal control theory to design an event-based, minimum energy, desynchronizing control stimulus for a network of pathologically synchronized, heterogeneously coupled neurons. This works by optimally driving the neurons to their phaseless sets, switching the control off, and letting the phases of the neurons randomize under intrinsic background noise. An event-based minimum energy input may be clinically desirable for deep brain stimulation treatment of neurological diseases, like Parkinson's disease. The event-based nature of the input results in its administration only when it is necessary, which, in general, amounts to fewer applications, and hence, less charge transfer to and from the tissue. The minimum energy nature of the input may also help prolong battery life for implanted stimulus generators. For the example considered, it is shown that the proposed control causes a considerable amount of randomization in the timing of each neuron's next spike, leading to desynchronization for the network.

Thermodynamic analysis of solar thermochemical CO2 capture via carbonation/calcination cycle with heat recovery

Thermodynamic analysis of an ideal solar-driven cycle for the capture of carbon dioxide using a CaO-based carbonation/calcination cycle is performed for gas mixtures with compositions corresponding to those of atmospheric air and power plant flue gases. Solar energy input requirements are examined as a function of CO2 molar fraction in the input gas, gas phase heat recovery, solid phase heat recovery, and carbonation and calcination temperatures. Gas phase heat recovery can reduce the solar energy input requirements by 22–99%, with the largest gains occurring at lower CO2 molar fractions. Solid phase heat recovery can reduce the solar energy input requirements by 0.1–26%, with the largest gains occurring at higher CO2 molar fractions. For a carbonation temperature of 673 K and a calcination temperature of 1273 K, over 45 MJ per mol of CO2 captured is required for a CO2 concentration of 300 ppm with no heat recovery. The minimum solar energy input required with perfect gas and solid heat recovery is 207 kJ per mol of CO2 captured.

Minimum-Energy Point-to-Point Trajectory Planning for a Motor-Toggle Servomechanism

In this paper, we propose a novel minimum-energy point-to-point (PTP) trajectory planning method for a motor-toggle servomechanism, which is described by the mathematical model of a mechatronic system. To generate the mechatronic trajectory, we employed the real-coded genetic algorithm (RGA) to search for the minimum-energy trajectory for the PTP motion profile, which is described by a polynomial with suitable conditions of position, velocity, and acceleration at the start and end points. The RGA algorithm determines the coefficients of polynomials with the fitness function of minimum-energy input, and is performed in numerical simulations and experiments. The results are compared with those of the S-curve by a traditional proportional-integral control. The proposed methodology can also be applied to any mechatronic system driven by a motor.

Influence of Aeration Rate on the Physio-Chemical Characteristics of Biodried Dairy Manure - Wheat Straw Mixture

Animal manure is a prime candidate for thermochemical conversion (co-firing, gasification, and pyrolysis) except for its high moisture content. Biodrying is a promising solution to reduce manure moisture with minimum energy input. This study investigated the effects of different aeration rates; low (0.05 L/min/kg VM), medium (0.80 L/min/kgVM), and high (1.50 L/min/kgVM), on the biodrying of dairy manure mixed with wheat straw. The moisture content dropped in 21 days from 56% to 28%, 34%, and 35% wb under high, medium, and low aeration rates, respectively. The heating value of the mixture decreased from 16.19 MJ/kgdry to 14.31, 13.79, and 13.83 MJ/kgdry under high, medium, and low aeration, respectively. Evaluation of energy consumption to remove a unit mass of moisture showed that high aeration levels required the least energy input, 7.84 MJ/kgH2O, followed by low aeration at 7.93 MJ/ kgH2O, while the medium aeration had a relatively high energy cost for water removal, 9.09 MJ/ kgH2O. The high aeration level was superior in terms of both drying energy and time requirements to the other rates considered. Comparison showed that high aeration level biodrying (1.50 L/min/kgVM) exceeded the range of conventional drying energy demand. However, the ratio of external fossil fuel demand was much lower in biodrying (due to the auto-thermal effect) than in conventional drying.

Heat Dissipation using Minimum Counter Flow Jet Ejection During Spacecraft Re-Entry

Abstract A major problem of spacecraft re-entry is the extreme heat generated. Sink and ablation cooling are commonly used but the cost of building and implementing such heat protection systems is very high. The issue of heat dissipation has, therefore, been an extensive area of research. Various passive and active methods of flow control have been attempted. Unfortunately, no viable cost effective methodologies have yet been possible to develop. At the University of New South Wales, various methods of active flow control technologies for application to subsonic and supersonic flows with a bias towards higher efficiency and lower energy usage are been explored. In this paper, a new approach of deploying minimum counter flow jet ejection as an active flow control method for heat dissipation is attempted. The concept relies on imparting sufficient momentum on the strong bow shock wave formed to induce oscillation but low enough to avoid instability during the flow interaction. To test the concept, an Apollo command module has been employed. It has been subjected to a free stream Mach number of 3 and a two-dimensional numerical flow simulation using ANSYS as the computational fluid dynamics tool has been performed for several cases of counter flow jet injection imparted on the bow shock wave formed and the interaction with the oncoming flow through the frontal stagnation point of the test module and compared with no injection case. Results obtained are highly promising. It appears that substantial heat reduction on the body is possible using the new approach. This finding may be of high practical significance and open up the possibility of developing a new thermal protective system using active flow control of dissipating and reducing heat during spacecraft re-entry with minimum energy input.

An Minimum-Energy-Based High-Degree Polynomial Trajectory Planning and Tracking Control for an LCD Glass-handling Robot

A new method of minimum-energy point-to-point (PTP) trajectory planning is proposed for an LCD glass-handing robot, which is driven by a permanent magnet synchronous motor (PMSM). The variable structure controller (VSC) is designed to track the trajectories and compensate LuGre model of frictional torque effects. The robot system is described by a mechanical equation and an electrical equation. To generate the minimum-energy trajectory, we employ a high-degree polynomial with suitable end-point conditions. The real-coded genetic algorithm (RGA) is used to search for the coefficients of the polynomial with the fitness function of minimum-energy input. Finally, numerical simulations of the minimum-energy inputs are compared for various degrees of polynomials. It is concluded that the proposed methodology can effectively design the minimum-energy trajectory, and the nonlinear VSC can track the designed trajectories for the robot system driven by a PMSM.

Dimensionless analysis of the global techno-economic feasibility of solar-hydrogen systems for constant year-round power supply

A novel dimensionless approach to analysing the capability of a solar electricity supply system with seasonal hydrogen storage to supply a constant load throughout the year is presented. The only input required specific to the location is its solar ratio, defined as the minimum daily solar energy input during the year divided by the maximum. As well as yielding an estimate of the saving in installed primary solar electricity generating capacity, the approach gives an indicative evaluation of the economic viability of adding the hydrogen storage to a photovoltaic-based solar supply, either for a large-scale grid or small scale autonomous application. The model has been validated using the results obtained from the more comprehensive RSHAP simulation model (RMIT Solar-Hydrogen Analysis Program). The dimensionless model is applied to a selection of 78 cities with varying latitudes across all five continents. For a round-trip storage efficiency of around 45% and the base-case unit costs of components assumed, solar-hydrogen systems would be economic in 55% of these cities. At 50% storage efficiency and/or lowered unit costs, solar-hydrogen systems would become viable in the vast majority of the cities, excepting those near the equator where the net benefits of adding storage are lower because of the more constant solar radiation over the year.

Silicon-based bridge wire micro-chip initiators for bismuth oxide–aluminum nanothermite

We present a micro-manufacturing process for fabricating silicon-based bridge wire micro-chip initiators with the capacity to liberate joules of chemical energy at the expense of micro joules of input electrical energy. The micro-chip initiators are assembled with an open material reservoir utilizing a novel 47 °C melting point solder alloy bonding procedure and integrated with a bismuth oxide–aluminum nanothermite energetic composite. The electro-thermal conversion efficiency of the initiators is enhanced by the use of a nanoporous silicon bed which impedes thermal coupling between the bridge wire and bulk silicon substrate while maintaining the structural integrity of the device. Electrical behaviors of the ignition elements are investigated to extract minimum input power and energy requirements of 382.4 mW and 26.51 µJ, respectively, both in the absence and presence of an injected bismuth oxide–aluminum nanothermite composition. Programmed combustion of bismuth oxide–aluminum nanothermite housed within these initiators is demonstrated with a success rate of 100% over a 30 to 80 µJ range of firing energies and ignition response times of less than 2 µs are achieved in the high input power operation regime. The micro-initiators reported here are intended for use in miniaturized actuation technologies.

Energy-based design optimization of steel building frameworks using nonlinear response history analysis

Presented in this paper is a design optimization method for steel building frameworks subjected to seismic loading using a nonlinear response history analysis procedure. Minimum weight, minimum seismic input energy and maximum hysteretic energy of fuse members are identified as the three design objectives. Design constraints include the limits on inter-story drift and plastic rotation of member sections. The design optimization method employs a multi-objective genetic algorithm to search for optimal member section sizes from among commercially available steel section shapes. The design method is illustrated for a moment-resisting steel frame of a three-story building. It is concluded the proposed optimization methodology is an effective and efficient application of the capacity-design principle to building frameworks under earthquake loading.