Converting the traction power of kites into electricity can be a low cost solution for wind energy. Reliable control of both trajectory and tether reeling is crucial. The present study proposes a ...modelling framework describing the dynamic behaviour of the interconnected system components, suitable for design and optimization of the control systems. The wing, bridle, airborne control unit and tether are represented as a particle system using spring-damper elements to describe their mechanical properties. Two kite models are proposed: a point mass model and a four point model. Reeling of the tether is modelled by varying the lengths of constituent tether elements. Dynamic behaviour of the ground station is included. The framework is validated by combining it with the automatic control system used for the operation of a kite power system demonstrator. The simulation results show that the point mass model can be adjusted to match the measured behaviour during a pumping cycle. The four point model can better predict the influence of gravity and inertia on the steering response and remains stable also at low tether forces. Compared to simple one point models, the proposed framework is more accurate and robust while allowing real-time simulations of the complete system.
•We present a kite power system model with an improved one- and 4-point kite model.•It includes a dynamic model of the winch and a segmented tether model.•The sensitivity of the models for steering input was validated with measurement data.•The flight paths of the models have been validated using measurement data.•The models can simulate kite power systems with a high accuracy in real time.
New kite-shaped textures are designed in this paper to improve the lubrication performance of tribological systems under hydrodynamic lubrication. Moreover, pressure distribution and load-carrying ...capacity of the kite-shaped textures under fixed working conditions are solved using Reynolds' equation based on the form of mass conservation. Lastly, the influence of kite-shaped textures on the friction coefficient under different geometric parameters is investigated. Moreover, a double-layer composite kite-shaped texture is designed, and the influence of parameters on lubrication performance is investigated. Numerical simulations and experiments are used to find the optimal parameters and effectively reduce the friction coefficient, thus providing a reference for reducing frictional wear in mechanical systems under full-film oil lubrication conditions.
Anthropogenic activity results in production of wastes, including litter in the environment. The problem of waste pollution is especially noticeable and usually discussed from the perspective of ...marine environments. It is significantly less addressed in terrestrial habitats, where the spatial dispersion of litter makes it difficult to assess the degree of pollution and its impact on the ecosystems. In this study, we present the problem of littering the terrestrial environments in the context of their inclusion in raptor nests, which are relatively rare elements of these ecosystems and because they comprise the top positions in their trophic chains, are exemplary bioindicators. During the breeding season we quantitatively and qualitatively assessed the anthropogenic debris present in the nests of 48 Back Kites (Milvus migrans) and Red kites (Milvus milvus). We found that the prevalence of litter in the nests was 100% for both species. The average number of litter items and average total area of litter recorded per nest was 31.3 and 0.44 m2, respectively and differed between species, where higher values were recorded for the Black Kite than for the Red Kite (53.1 vs. 23.8 and 0.54 m2 vs. 0.34 m2, respectively). Taking into account the average nest surface area of both studied species (0.33 m2 and 0.57 m2, respectively), obtained values indicate large littering of the studied nests. Furthermore, 71% of identified debris items were plastics which constituted 65% of the total surface of all recorded debris. Our study suggests a high availability of litter in the terrestrial habitats that constitute the breeding territories of the two sympatric study species.
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•We studied litter in nests of Red and Black Kites.•The prevalence of litter was 100%.•On average 32.1 litter items with a total area of 0.44 m2 were recorded per nest.•The study suggests a high availability of litter in kite territories, ergo – terrestrial ecosystems.
The flavonoid naringenin is abundantly present in pomelo peels, and the unprocessed naringenin in wastes is not friendly for the environment once discarded directly. Fortunately, the hydroxylated ...product of eriodictyol from naringenin exhibits remarkable antioxidant and anticancer properties. The P450s was suggested promising for the bioconversion of the flavonoids, but less naturally existed P450s show hydroxylation activity to C3′ of the naringenin. By well analyzing the catalytic mechanism and the conformations of the naringenin in P450, we proposed that the intermediate Cmpd I ((porphyrin)Fe = O) is more reasonable as key conformation for the hydrolyzation, and the distance between C3′/C5′ of naringenin to the O atom of CmpdI determines the hydroxylating activity for the naringenin. Thus, the “flying kite model” that gradually drags the C-H bond of the substrate to the O atom of CmpdI was put forward for rational design. With ab initio design, we successfully endowed the self-sufficient P450-BM3 hydroxylic activity to naringenin and obtained mutant M5-5, with
k
cat
,
K
m
, and
k
cat
/
K
m
values of 230.45 min
−1
, 310.48 µM, and 0.742 min
−1
µM
−1
, respectively. Furthermore, the mutant M4186 was screened with
k
cat
/
K
m
of 4.28-fold highly improved than the reported M13. The M4186 also exhibited 62.57% yield of eriodictyol, more suitable for the industrial application. This study provided a theoretical guide for the rational design of P450s to the nonnative compounds.
Key points
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The compound I is proposed as the starting point for the rational design of the P450BM3
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“Flying kite model” is proposed based on the distance between O of Cmpd I and C3′/C5′ of naringenin
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Mutant M15-5 with 1.6-fold of activity than M13 was obtained by ab initio modification
Graphical abstract
A Kite-based Airborne Wind Energy Conversion System (KAWECS) works by harnessing the kinetic energy from the wind and converting it into electric power. The study of the dynamics of KAWECS is ...fundamental in researching and developing a commercial-scale KAWECS. Testing an actual KAWECS in a location with suitable wind conditions is only sometimes a trusted method for conducting research. A KAWECS emulator was developed based on a Permanent Magnet Synchronous Machine (PMSM) drive coupled with a generator to mimic the kite’s behaviour in wind conditions. Using MATLAB-SIMULINK, three different power ratings of 1 kW, 10 kW, and 100 kW systems were designed with a kite surface area of 2.5 m2, 14 m2, and 60 m2, respectively. The reel-out speed of the tether, tether force, traction power, drum speed, and drum torque were analysed for a wind speed range of 2 m/s to 12.25 m/s. The satellite wind speed data at 10 m and 50 m above ground with field data of the kite’s figure-of-eight trajectories were used to emulate the kite’s characteristics. The results of this study will promote the use of KAWECS, which can provide reliable and seamless energy flow, enriching wind energy exploitation under various installation environments.
We investigate a construction of an integral residuated lattice starting from an integral residuated lattice and two sets with an injective mapping from one set into the second one. The resulting ...algebra has a shape of a Chinese cascade kite, therefore, we call this algebra simply a kite. We describe subdirectly irreducible kites and we classify them. We show that the variety of integral residuated lattices generated by kites is generated by all finite-dimensional kites. In particular, we describe some homomorphisms among kites.
Introduction: Kites were first introduced by the Chinese more than three thousand years ago, but in places like India, Pakistan and Afghanistan, Kite flying is celebrated in unique way. People enjoy ...cutting down others kites and there is an instinct to catch the threads of the “Cut-Kite” and rejoice the gain. In this study conducted at a tertiary care emergency medicine department to understand demographic profile and injuries related in such a festive celebration, occurring in one urban area, to spread awareness and reduce such incidence.
Methodology: This cross-sectional descriptive study was conducted using preformatted form in consecutive two year.
Results: Among 83 cases we studied, 81% were male. 65% were in the age group of 11-40. 70% incidences took place in noon and evening hours. 68.67 % presented in 108 ambulance services, 43% presented with fall from height (terraces), 34 % had road traffic accidents because of strings and festival related excitement. Maximum had fall from 1 storey buildings. 56% received Out Patient based treatment. Among the admitted patients 15% had head injury, 2 cut throat, 9.7% had fractures and 1 had to undergo laparotomy, 2 died eventually during the hospital stay because of grievous injuries.
Conclusion: This study re-emphasizes the importance of spreading awareness and increasing the care, particularly of children during such an enjoyable festival.
Energy harvesting based on tethered kites benefits from exploiting higher wind speeds at higher altitudes. The setup considered in this paper is based on a pumping cycle. It generates energy by ...winching out at high tether forces, driving an electrical generator while flying crosswind. Then it winches in at a stationary neutral position, thus leaving a net amount of generated energy.
The focus of this paper is put on the flight control design, which implements an accurate direction control towards target points and allows for a flight with an eight-down pattern. An extended overview on the control system approach, as well as details of each element of the flight controller, is presented. The control architecture is motivated by a simple, yet comprehensive model for the kite dynamics.
In addition, winch strategies based on an optimization scheme are presented. In order to demonstrate the real world functionality of the presented algorithms, flight data from a fully automated pumping-cycle operation of a small-scale prototype are given. The setup is based on a 30m2 kite linked to a ground-based 50kW electrical motor/generator by a single line.
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•Energy generation by flight and winch control in pumping cycles.•Control design based on a simple model for tethered kite dynamics.•Overview on flight control setup and detailed description of respective elements.•Pattern control by target points and winch strategies for different cycle phases.•Discussion of data from a 30m2 kite linked to a ground-based 50kW motor/generator.
This manuscript documents an engineering proof of concept. We demonstrate that a deep-water demersal trawl targeting northern shrimp (Pandalus borealis) can be spread without otter boards using ...nothing more than flexible foils (i.e., kites) mounted near the wings of the trawl. A combination of numerical simulation, physical modeling in a flume tank, and full-scale sea trials were used to optimize the horizontal spreading of the demersal trawl. Spacing between the foils and the angle of attack to the direction of tow were found to be important parameters. To our knowledge this is the first successful attempt to spread a demersal trawl full-scale at-sea using nothing but flexible foils.
•A proof of concept – using foils to spread a deep-water demersal trawl without otter boards or contact with the seabed.•Numerical simulation, physical modeling in a flume tank, and sea trials were used to develop the innovative technology.•Spacing between the kites and angle of attack were found to affect the lift and drag of the fishing system.
This paper presents two novel semi-analytical models for predicting the aerodynamic performance of crosswind kite power systems (CKPSs), where the kite induction effects on the oncoming flow are ...taken into account. The blade element momentum theory forms the backbone of the models. The effects of reel-out ratio, solidity factor, rotor incidence angle, side-slip angle and tether drag are included in the formulation for the axial induction factor and power output. For simplicity, the wake rotation and the tangential induction factor are neglected. Aerodynamic model 1 is developed for predicting the reel-out power with uniform inflow assumption, and it is suitable for CKPSs with ground-based power generation. Aerodynamic model 2, on the other hand, can predict both the reel-out and torque powers with either uniform or non-uniform inflow assumption, and the model can be used for CKPSs with ground-based, or on-board power generation, or with the combination of the two. Some parametric studies have been conducted for a generic kite system with pre-defined aerodynamic efficiency parameters to highlight the effects of incidence and side-slip angles. In addition, a particular CKPS and its variants are examined to show the individual and combined effects of incidence angle, side-slip angle, tether drag and airfoil shape on the induction factor and power output.
•Two semi-analytical aerodynamic models for crosswind kites have been developed.•Induction effects, elevation, side slip and tether drag have been considered.•Aerodynamic model 1 can be used for predicting power output of pumping kites.•Aerodynamic model 2 is suitable for pumping mode, drag mode or their combination.•Aerodynamic model 2 can be used with non-uniform inflow distribution at the rotor.
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