Energy Margin Research Articles

High temperature superconductors for fusion applications and new developments for the HTS CroCo conductor design

Recent improvements in the superconducting performance and technical maturity of high-temperature-superconductors (HTS) lead to considerations of using HTS in future fusion magnets in addition to the presently used low-temperature superconductors (LTS). Compact high field magnet systems entirely made of HTS for compact tokamaks, hybrid HTS-LTS magnets for enhanced operational capabilities (e.g. larger flux swing) in conventional tokamaks and future stellarator devices with HTS magnet systems are presently investigated. An overview of recent concepts, developments and designs of HTS-based future fusion magnet systems is given and a number of physical and technical challenges will be addressed, too: In particular, the so-called second generation HTS Rare-Earth-Barium-Copper-Oxide (REBCO) shows an excellent superconducting performance over a wide range of magnetic fields and temperatures. The layered architecture of these technical REBCO conductors and the ceramic nature of REBCO lead to mechanical challenges at high Lorentz forces, which is relevant for cable-in-conduit-conductors (CICC) of future fusion magnets due to the high currents and high field strengths. Different high-current cable concepts for future fusion magnets are discussed. High loads are not only a challenge for potential future HTS conductors but also for the conductor jackets and the coil casing of the magnet systems. An increase of the numbers of load cycles on the path towards a future fusion power plant requires superior mechanical strength. The high critical temperature of HTS materials allows to design HTS CICC with a noticeably higher minimum quench energy and temperature margin compared to LTS conductors – but leads inevitably to substantially slower quench propagation velocity and challenges related to quench detection. Recent results from numerical modeling and experimental investigation of quench in high-current HTS CrossConductor (HTS CroCo) based CICC are addressed.

Sodium Retrieval from Sap May Permit Maintenance of Carbohydrate Reserves in Mature Xylem Tissues of a Salt-tolerant Hybrid Pistachio Rootstock Exposed to 100 mm NaCl

Salinity’s many stresses may not kill a relatively salt-tolerant perennial in one season, but they can still deplete or modify nonstructural carbohydrate (NSC) pools. Any change to the quantity or quality of NSC reserves may have detrimental effects on phenology and reproduction, as well as yield, in tree crops. This study integrates salinity’s infringement on the energy margins of pistachio rootstock ‘UCB-1’ (an interspecific hybrid of Pistacia atlantica and P. integerrima) at senescence by measuring sugar and starch pools in wood, bark, and roots after treatment with ≈100 days of moderate to high salinity (50–100 mm NaCl and 10–20 mm CaCl2). Supported by a second experiment using sodium orthovanadate (NaOV) to block active xylem retrieval in the same hybrid pistachio rootstock, we conclude that retrieval of Na+ from xylem sap may allow for the preservation of NSC pools (particularly, starch) in mature xylem tissues by limiting the demand for carbon-based osmoticum (sugars). In contrast, younger growing tissues (bark and fine roots) were found to counteract salinity by degrading carbon-dense starch into osmotically active sugars at the expense of total NSC reserves, suggesting a physiological shift toward protection/isolation from environmentally pervasive but potentially toxic salts in these tissues.

Feasibility study of novel rapid ramp-down procedure in MgB2 MRI magnet using persistent current switch with high off-resistivity

Dry magnets using high temperature superconductors and MgB2 are attractive options to depart from dependence on liquid helium in MRI scanners. In the dry magnets, however, lack of thermal mass of cryogen makes a controlled quench difficult and extends time for restarting the magnets after the quench. In this study, a novel rapid ramp-down procedure, which can be substituted for the controlled quench in emergency rundown, is proposed, and its feasibility is proven for a 1.5 T whole-body MgB2 MRI magnet. In this procedure, a power supply receives current from a persistent current switch (PCS), the PCS is turned off by heating, the power supply is interrupted by a breaker, and the stored energy in the magnet is mostly consumed at an external resistor. Owing to the large energy margin of MgB2 wires, the AC loss during the ramp-down does not bring a quench of the MgB2 coils. A niobium–titanium sheathed MgB2 wire 0.60 mm in diameter is made, and a PCS with high off-resistivity is designed using this wire. The shunt current during the ramp-down does not bring the burnout of the PCS when the wire length is sufficiently long, typically hundreds of metres. Because heat generation inside the cryostat during the ramp-down is a few per cent of the stored energy in the magnet, the magnet is not heated excessively. As a result, the proposed ramp-down procedure should shorten the downtime of MRI scanners.

Soybean and maize cultivation in South America: Environmental comparison of different cropping systems

Maize and soybean are two widely spread crops for food, feed and biofuel production, and in South America there are some of the most important producing countries in the world. This study investigates the environmental impact linked to their agricultural production in a sub-tropical South American context, starting from primary data relating to a cultivated area in eastern Paraguay. To this end, the Life Cycle Assessment approach was adopted in a cradle-to-farm gate perspective, evaluating eight different impact categories. In particular, two widespread intra-annual rotations were compared, both of which consider soybean as a first-season crop, alternating in the second-season with maize or soybean itself. Environmental results were expressed both in a crop-to-crop approach (per t of individual product) and with four different units expressing the land management function (1 ha year −1 ); the productive function (1 GJ ha −1 year −1 and 1 t of crude protein ha −1 year −1 ) and finally the financial function (1 USD of gross margin ha −1 year −1 ) of the two different cropping systems. In the cropping system approach, results expressed per hectare of cultivated area and per t of crude protein produced do not see one cropping system performing better than the other consistently over the evaluated impact categories. The soybean-maize rotation, on the other hand, appeared clearly more efficient from an environmental point of view in terms of gross energy and gross margin produced per hectare per year. The lack of a shared consensus on the most appropriate and comprehensive way to express the results of LCA studies on cropping systems makes difficult the selection of the best system. In particular, there are still on-going limitations and controversies in selecting the most appropriate functional unit for cropping systems LCA. • The environmental impact for different crop system was evaluated. • LCA was applied with a from cradle to farm gate perspective. • Different functional unit were considered. • The soybean-maize rotation is more efficient from an environmental point of view. • Depending on the selected functional unit the relative comparison changes.

Techno Economic Evaluation and Feasibility Analysis of a Hybrid Net Zero Energy Building in Pakistan: A Case Study of Hospital

The current study is an economic evaluation and feasibility study of hybrid microgrid Net Zero Energy Buildings in Pakistan. A Net Zero Energy approach is proposed for a two-story hospital building situated in Taxila, Pakistan. Consequently, to design a hybrid Net Zero Energy Building, the solar radiation potential of the subject location and electricity usage of the hospital are estimated. The proposed hybrid microgrid Net Zero Energy Building comprises photovoltaic modules and converters. However, the thermal load is computed as a grid-connected hybrid system. Economic evaluation is performed by using economic indicators of the net present cost and the payback period. Also, initial and operational costs are determined, to determine the profitability of the project. Results show that the analysis is a cost-effective approach and has a payback period of 2.53y. Additionally, the per-unit cost of electricity is reduced to 0.12 USD/kWh. Moreover, the energy produced by a hybrid system is 10.24% more economical than that of the pre-working grid system. Results explain the reduction in the cost of energy and profit margin in electricity generation and the increase in electricity production and feasibility of hybrid Net Zero Energy Buildings in Pakistan. Research will help to develop an approach toward an IEA task 47 in Pakistan with the possible development of simulation-based installations of Net Zero Energy Buildings in the health sector in Pakistan.

Profitability of insect farms

Despite growing interest from entrepreneurs, knowledge on the profitability of commercial-scale insect production is scarce. Insight into the economic figures of insect production is needed by farmers aiming to start insect farms, by banks seeking to provide financing, and by governments planning policy interventions. This review provides an overview of the profitability and underlying economic figures relating to the production of Hermetia illucens, Alphitobius diaperinus, Tenebrio molitor and Acheta domesticus. To enhance data interpretation, we also provide a brief overview of the global insect sector, with specific attention to farm-level operational practices. Sales prices refer to fresh larvae, dried larvae or larvae meal, whereas operational costs include costs for feed, labour, electricity, water and gas. Operational cost components differ per insect species, and therefore the relevant margins are specified for three insect species. The energy, feed, and labour margin for production of H. illucens ranges from € -798 to 15,576 per tonne of dried larvae. The feed and labour margin for production of T. molitor ranges from € 7,620 to 13,770 per tonne of fresh larvae. For production of A. domesticus the feed margin ranges from € 12,268 to 78,676 per tonne of larvae meal. The margin range for A. diaperinus cannot be estimated, due to a lack of data in the literature. The ranges mainly reflect the differences in sales prices, which are found to heavily depend on the geographical market location, type of market (feed or food) and quantity sold. Major operational costs include feed and labour, with feed costs varying substantially within and between insect species. The economic figures and margins presented in this article provide a foundation for the further development of the insect production sector.

Effects of Environment Temperature on The Attenuation of Quasi-Spherical EFP Velocity

A comparison of multiple quasi-spherical EFP warhead tests conducted during different seasons of the year revealed that EFP velocities in the cold season were low. In this paper, the experimental phenomenon is analyzed theoretically base on the principles of EFP and flight dynamics. Due to the difference of air density caused by the different temperature, the aerodynamic drag of EFP with the same aerodynamic shape and initial velocity is obviously different. Because of the hypervelocity of EFP, The impact velocity of EFP on target is also significantly affected after flying over 100 meters. In the paper, the flight velocities of a quasi-spherical EFP at different temperatures is calculated by MATLAB, which is in good agreement with the experimental results. It is necessary to consider the change of environment temperature in engineering practice of quasi-spherical EFP warhead in order to improve kinetic energy margin.

Critical current density defined at low electric field criterion and energy margin of superconducting MgB2 wires in wide temperature and magnetic field range

High-temperature superconductors (HTS) and MgB2 may potentially improve the usability of superconducting magnets dramatically owing to their large energy margin. When HTS and MgB2 wires are used for magnets operated in the persistent current mode, such as in magnetic resonance imaging (MRI) scanners, the electric field generated in the wires must be lower than 10−10 V m−1. In this paper, critical current density, J c, defined at an electric field criterion of 10−10 V m−1 is evaluated from a magnetisation decay measurement for state-of-the-art monofilamentary MgB2 wires. By using the obtained J c, a critical line of our multifilamentary MgB2 wire is shown on the temperature-magnetic field plane. Here, the critical line is defined as a line on which an electric field of 10−10 V m−1 is generated at a coil current density of 150 A mm−2. The area inside the critical line is demonstrated to be large enough to fulfil the requirement of 1.5 T MRI scanners operated at 10K–15K. In addition, the iso energy-margin lines are shown on the temperature-magnetic field plane and compared with those of NbTi wires. The MgB2 wire has an order of magnitude greater energy margin than the NbTi wires in most of the area inside the critical line. This suggests that the MgB2 wire is highly unlikely to be quenched due to mechanical disturbances.

Effect of wingtip connection on the energy and flight endurance performance of solar aircraft

This study explores the effects of wingtip connection on decreasing energy consumption and increasing flight endurance for solar aircraft. The Oswald efficiency factor, induced drag coefficient and power consumption are derived as the models of the number of wingtip connected aircraft. As the energy margin model is related to the number of connected solar aircraft, a flight endurance margin model is proposed to evaluate the advantages of wingtip connection quantitatively. With the numerical method developed, researches on the energy and flight endurance performance for a given example wingtip-connected solar aircraft are performed. Moreover, the impacts of solar cell efficiency, flight date and latitude on the advantages of wingtip connection for solar aircraft are explored. The results suggest that the wingtip connection design enables solar aircraft to decrease induced drag coefficient, increase flight endurance and range effectively when the aircraft is only powered by battery. The wingtip connection design is more effective to increase the flight endurance and improve the maximum perpetual flight latitude with more connected solar aircrafts and higher solar cell efficiency, especially in the flight condition with high solar elevation angle and more daylight hours. However, as the number of connected solar aircraft increases, the effect of one more connected aircraft on these advantages decreases because the effect of wingtip connection on decreasing induced drag coefficient decreases with increasing aspect ratio.

Sub-nW Microcontroller With Dual-Mode Logic and Self-Startup for Battery-Indifferent Sensor Nodes

In this article, a battery-indifferent microcontroller unit (MCU) with wide power-performance scaling is presented to enable continuous operation with a sub-mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> on-chip solar cell, even when the battery runs out of energy. The MCU is based on dual-mode standard cells to extend power-performance flexibility well beyond allowed by voltage-scaled CMOS logic. Ripple power gating is introduced to allow the processor to boot under scarce light intensity and no battery energy. The dual-mode logic is experimentally characterized at the gate level, analyzing the underlying tradeoffs among power, energy, delay, and noise margin. Compared with voltage-scaled CMOS logic, dual-mode logic is shown to reduce the minimum power/gate by 750 × to enable purely harvested operation while having comparable energy/gate to prolong battery-powered operation. The proposed ripple power gating self-startup technique enables MSP430-compatible MCU cold start with an on-chip 0.54-mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> solar cell at a dim 55-lx light condition.

RETRACTED ARTICLE: Multi objective dragonfly algorithm for congestion management in deregulated power systems

Congestion in transmission corridors are the major bother for deregulated power system’s operation. Generator rescheduling along with demand alteration is a traditional remedy for transmission line congestion. According to market clearing process, the system operator (SO) has to pay a certain amount of cost to the market participants for rescheduling the generation and demand. This kind of redispatch related congestion management (CM) procedure is mainly carried out to reduce the congestion cost, but they are failing to provide an attention in power systems security. The risky generator’s power shifts may diminish the voltage and transient stability of the power system. So power system security should be included in the congestion management procedure. In this proposed multi objective congestion management procedure, rescheduling of active power is carried out to improve/retain the power systems security along with a congestion cost reduction. Voltage security margin (λ) and corrected transient energy margin (CTEM) provides a measure for power system security level. Multi Objective Dragonfly Algorithm (MODA) is employed to trace the non dominated solutions for three conflicting objectives. Fuzzy decision making principle is applied to select the best Pareto solution depends on the objective’s significances. The goodness of the MODA optimization approaches is experimented in congestion alleviation of New England 39 bus systems and solutions are compared with some reputed methods.

PRECISION OF ANTHROPOMETRIC EQUATIONS TO ESTIMATE TOTAL ENERGY EXPENDITURE OF OLDER ADULTS WITH SARCOPENIA: A CROSS SECTIONAL STUDY

Purpose: The accuracy and errors of prediction of equations that estimate energy expenditure are unknown to seniors with sarcopenia. This study assessed the precision of predictive equations to estimate energy needs of sarcopenic seniors. Methods: Ninety-four community-dwelling older adults (female: 66; mean age: 75.9[5.7]) were tested for body dimensions derived from DXA. Performance tests and diagnosis of sarcopenia were performed. The total energy expenditure (TEE) of sarcopenic seniors (n=10) was measured by accelerometry and compared with three anthropometric equations: DRIs, Escott-Stump with upper (Escott-Stumpupp) and low energy margin (Escott-Stumplow). Results: Except for height, all other variables of body dimensions of sarcopenic seniors were smaller than non-sarcopenic ones (p&lt;0.05). The slightly lower TEE values in the Escott-Stumplow equation were not different from accelerometry (-53kcal; t=0.606; p=0.560) but were overestimated by the DRIs (+358kcal; t=-3.163; p=0.011) and Escott-Stumpupp (+240kcal; t=-5.817; p&lt;0.001), confirmed due to lack of agreement (Bland-Altman) with measured TEE. Conclusion: Smaller body dimensions of sarcopenic seniors suggest that their energy needs should be estimated from specific resources. The TEE assessed by the Escott-Stumplow equation was similar to that measured by accelerometry and therefore may be a good alternative for sarcopenic seniors where direct measurement of TEE is not possible.

Review On Optimal Mathematical Workload Allocation Models In Energy Consumption Using Fog-Cloud Networks

This paper provides information regarding different approaches in terms of energy consumption and delay in transmission which helps in finding out the optimized solution over fog-cloud networks. As we are very much familiar about the concept of cloud and fog computing which holds huge amount of data via different routing protocol and many other sources. Also, there is increase in need of localized services of mobile users. For such cases, we have insufficient in cloud resources which motivates the access of fog based computing these days. It provides the resources locally to the users which pre-stores data used in cloud and then distributes to the end users with fast-rate. Generally, routing of data consumes lots of energy or power because it follows the concept of packet forwarding through various intermediate networking nodes in a systematic manner. There are several factors and metrics which helps in optimizing power consumption for routing activity as provided minimum of the power and delay. The paper includes introduction of basic concept of minimization of energy consumption and margin in fog- cloud networks and discuss about some more optimized techniques to simplify the results. Also, we developed a problem based on workload allocation which suggests the best way to allocate workload in between the fog-cloud networks by considering minimum energy consumption with the specific constrained service delay. For better simulation, the mentioned problem can be divided in to three sub problems relative to subsystems. Each sub problem can be solved individually by considering some networking constraints and after that we combine three subsystems and get the minimized results in terms of energy consumption and delay in transmission. We use primal problem using approximation method in this case. Finally, we propose some more modified techniques by considering previous simulations and numerical results so that we can get more accuracy in results. This helps in saving of communication bandwidth, improvement in performance of fog and cloud computing.

An Evaluation of Flux-Coupling Type SFCL Placement in Hybrid Grid System Based on Power Quality Risk Index

Due to the expansion of restructured electricity markets and consequently power network operation approaching dynamic and static margins, the probability of transient instability has remarkably been increased. To reduce the transient instability risk or probabilistic cost of power quality, the present study focuses on determining the optimum location of a flux-coupling type SFCL. To this end, the candidate locations with lower related transient instability risk are selected as the best locations for installing flux-coupling type SFCLs. Nowadays, the type of SFCL employed in this study, which enjoys the benefits of both resistive and inductive type SFCLs, is a suitable means for enhancing the transient stability of electrical grids. Despite being another useful approach in transient stability evaluation, the equal-area criterion is merely restricted to the analysis of the stability of a single-machine power system connected to an infinite bus and also a two-machine power system. The online approach employed in this study is based on the corrected transient energy margin (CTEM), some probabilistic factors, and the cost of transient instability. Furthermore, CTEM index is a useful tool for calculating the critical clearing time (CCT). Therefore, in recent years, this index has become more and more useful. The studies carried out on the IEEE New England 39-bus test system ascertain the high applicability of the proposed method.

Effect of solar cell efficiency and flight condition on optimal flight control and energy performance for Z-shaped wing stratospheric solar aircraft

The parameters of solar cell efficiency, flight date of year, latitude and sun elevation angle are important to energy conversion of solar cells, which affect optimal flight control and energy performance of Z-shaped solar aircraft. This work is mainly focusing on studying the effect of varying these parameters on optimum attitude planning, optimum wing morphing control and maximum net energy input for Z-shaped solar aircraft. This study shows that, with higher solar cell efficiency, the solar aircraft prefers to more daylight hours configured as Z-shaped wing, larger morphing angle and larger angle between projection of sunlight and wingspan axis, which enhances to achieve more net power input. For the middle and high latitudes in winter with low sun elevation angles, the Z-shaped solar aircraft tends to large morphing angles and small angles between projection of sunlight and wingspan axis. For the low and middle latitudes of the other seasons with high sun elevation angles, it prefers to small morphing angles to make its central wing totally expose to the sunlight, and orient flight attitude to make the projection of sunlight coincide with wingspan axis. Moreover, the research on the impact of solar cell efficiency shows that, compared with the planar wing, the optimal Z-shaped wing is more effective to improve energy margin and extend perpetual flight days with the same increase of solar cell efficiency. The results can provide valuable engineering reference on optimum wing morphing control and optimum attitude planning for Z-shaped stratospheric solar aircraft.

Influence of N-Substitution on the Formation and Oxidation of NHC–CAAC-Derived Triazaalkenes

We have studied the effect of N-substitution on the course of the reaction of imidazolium triflate. The reaction of N-heterocyclic carbene with N-tBu-substituted pyrrolinium triflate afforded 2-(pyrrolidin-2-yl)-imidazolium triflate, 3R. Treatment of 3R with potassium bis(trimethylsilyl)amide (KHMDS) leads to either the dealkylation product 4 or the deprotonation product, triazaalkene 5, depending on the N-substitution at the imidazolium moiety. Density functional studies using the B3LYP/TZVP setup have been employed to explore various pathways for the dealkylation reaction and the calculated energies support the dealkylation by a large energy margin compared to the deprotonatation process. Theoretical calculations revealed that dealkylation reaction is thermodynamically more favorable than deprotonation. The triazaalkene 5 could be oxidized by AgOTf to the corresponding radical cation 6 and dication 7 in-situ. While 6 and 7 could not be isolated, the formation of the former is inferred by electron paramagnetic resonance spectroscopy and its abstraction of a H-atom to afford 3Me. Similarly, the formation of the dication 7 is inferred by its ready elimination of isobutylene affording 8.

Energy optimization and investigation for Z-shaped sun-tracking morphing-wing solar-powered UAV

To achieve perpetual flight, solar-powered UAVs (SPUAVs) need to convert sufficient solar energy into electricity during daylight flight. However, perpetual flight at middle and high latitude regions in winter days still poses great challenges for gaining enough solar energy due to the low sun elevation angle and short daylight duration. Among measures for flight endurance enhancement, tracking the sun through changing geometry of wing and orienting flight direction may be an effective design scheme for gaining more solar energy. In this paper, the energy optimization method for Z-shaped sun-tracking morphing-wing SPUAV is developed and used to investigate the advantages on energy performance of the optimal Z-shaped wing over the conventional planar wing. Energy optimization for a whole year's flight shows that the optimal Z-shaped wing is capable of achieving longer flight endurance, improving perpetual flight latitude and extending perpetual flight date efficiently compared with the planar wing, especially for the middle and high latitude regions during winter days. The investigation on implications of conversion efficiency of solar cells indicates that, with higher conversion efficiency of solar cells, the optimal Z-shaped wing is more effective to collect more net energy, retain more energy margin and achieve perpetual flight at higher latitude. The Z-shaped sun-tracking morphing-wing design combined with the energy optimization method proposed is helpful to increase flight endurance and improve perpetual flight latitude for SPUAVs.

Identification of Key Influencing Factors of Sustainable Development for Traditional Power Generation Groups in a Market by Applying an Extended MCDM Model

With the deepening reform of the power market, the external environment of China’s power industry is going through a huge change. China’s traditional power generation groups (TPGGs), with assets all over the country, are, due to a lack of market awareness about energy policies, facing serious challenges in developing competitive advantages, improving power transaction modes, optimizing profit models, and even realizing basic corporate strategies. In this study, we focus on identifying the key factors influencing sustainable development in an unprecedented market environment for TPGGs, so as to achieve overall sustainable development for the whole power generation sector in China. A hybrid framework based on Multiple-Criteria Decision-Making (MCDM) was proposed to recognize the key influencing factors under vague rule conditions. We developed a novel method combining three different MCDM methods with triangular fuzzy numbers (TFNs), fuzzy Delphi, fuzzy Decision-Making Trial and Evaluation Laboratory (DEMATEL), and Analytic Network Process (ANP), to cover uncertainty and make the problem-solving approach closer to the actual problem. A series of analyses indicate that the final 14 factors covering the five dimensions are considered to be important factors in the sustainable development of TPGGs. Based on the results, it can be said that “Gross energy margin” and “Pricing bidding strategy” dominate the impacts of TPGG’s sustainable development. Finally, we give some advice relating to practical measures to help TPGGs achieve sustainable development in the market-oriented industry environment.

Thermal efficiency extends distance and variety for honeybee foragers: analysis of the energetics of nectar collection and desiccation by Apis mellifera.

The desiccation of nectar to produce honey by honeybees ( Apis mellifera L.) is an energy-intensive process, as it involves a quasi-isothermal change in the concentration of sugars from typically 20 to 80% by vaporization (honey ripening). This analysis creates mathematical models for: the collected nectar to honey ratio; energy recovery ratio; honey energy margin; and the break-even distance, which includes the factors of nectar concentration and the distance to the nectar from the nest; energetics of desiccation and a new factor, thermal energy efficiency (TEE) of nectar desiccation. These models show a significant proportion of delivered energy in the nectar must be used in desiccation, and that there is a strong connection between TEE and nest lumped thermal conductance with colony behaviour. They show the connection between TEE and honeybee colony success, or failure, in the rate of return, in terms of distance or quality of foraging. Consequently, TEE is a key parameter in honeybee populations and foraging modelling. For bee keeping, it quantifies the summer benefits of a key hive design parameter, hive thermal conductance and gives a sound theoretical basis for improving honey yields, as seen in expanded polystyrene hives.

Onboard trajectory generation for gyroplane unpowered landing based on optimal lift-to-drag ratio target

To achieve the autonomous unpowered landing for gyroplanes, an onboard trajectory generation method is presented in this paper. As a pivotal variable in the proposed method, the Lift-to-Drag Ratio will be uniquely determined in different phases by finding the maximum for the energy margin during approaching and the energy decrease at terminal landing. Especially, autorotation constraint, the primary requirement of gyroplanes for flight stability, has been considered as a limitation factor through this procedure. Furthermore, a geometrically constrained three-dimensional trajectory profile is employed, in which a multi-circle Heading Align Cone is proposed to improve its applicability. Accordingly, a predictor–corrector algorithm is derived and described for trajectory generation with initial variance and terminal requirements. Employing the algorithm onboard, by adjusting few geometric parameters dynamically, a feasible trajectory reference that meets the specified constraints can be generated efficiently. Results from numerical calculation and closed-loop simulation under different scenarios demonstrate the effectiveness and robustness of the approach.