Harvesting Structures Research Articles

Genetic control of parameters of harvest structure elements in the corn diallel complex

The article discusses the results of the use of diallel analysis in the study of self-pollinated maize lines. The average values of the elements of the structure of the grain yield in self-pollinated lines, as well as the average group indicators of hybrids, are noted. The effects of the general and dispersion of the specific combinative ability of lines are revealed. The ranking of the average group values of hybrids by the weight of the cob was carried out, which made it possible to arrange the lines in the following sequence: CL 7 < X 46 < SE 19 < Od 28 < KS 25 < LV 32 < Bg 1266 < Om 255 < Uk12 D 2 < RSK 25 < Om 232 < Mk 130 U < RSK 3 s< RSK 7 < RN 26 < Mk 11. In 2016-2019 A significant influence on the manifestation of the weight of the cob, the weight of the grain from the cob, the yield of grain, the number of grains in a row and the grains on the cob of the paratypical component of the dispersion (E) was noted.

A Gis-Based Parametric Analysis of Irrigational Tanks in the Oldest Civilized City in India-Madurai

The irrigational tanks being traditional Water harvesting structures designed by rulers and chieftains dating back centuries. These are constructed in such a way that they act as a major water resource in drought-prone rural communities. The main aim of this paper is to develop a GIS-based Parametric Maps of Maximum Capacity(MC), Maximum Water Level(MWL), Ayacut Area(AA), Water Spread Area(WSA), Sub-basins and Basins of irrigational Tanks which form the basic irrigation information system to assist agriculturalists, farmers, and Government organization for the proper maintenance of irrigation tanks with suitable indexing parameters, to mitigate & forecast the water and food requirements by evaluating currently available water for the given population density and irrigation lands. The study area selected is the oldest civilized city in India which is in the state of Tamilnadu-Madurai district, which is served by the Vaigai River and consists of 1338 tanks. This GIS-based information system assists the decision-makers to perform surveillance, evaluate the efficiency of the tank at any space & time and take proper managerial methods to utilize the resources economically.

Sand dams for sustainable water management: Challenges and future opportunities

Sand dams are impermeable water harvesting structures built to collect and store water within the volume of sediments transported by ephemeral rivers. The artificial sandy aquifer created by the sand dam reduces evaporation losses relative to surface water storage in traditional dams. Recent years have seen a renaissance of studies on sand dams as an effective water scarcity adaptation strategy for drylands. However, many aspects of their functioning and effectiveness are still unclear. Literature reviews have pointed to a range of research gaps that need further scientific attention, such as river corridors and network dynamics, watershed-scale impacts, and interaction with social dynamics. However, the scattered and partially incomplete information across the different reviews would benefit from an integrated framework for directing future research efforts. This paper is a collaborative effort of different research groups active on sand dams and stems from the need to channel future research efforts on this topic in a thorough and coherent way. We synthesize the pivotal research gaps of a) unclear definition of “functioning” sand dams, b) lack of methodologies for watershed-scale analysis, c) neglect of social aspects in sand dam research, and d) underreported impacts of sand dams. We then propose framing future research to better target the synthesized gaps, including using the social-ecological systems framework to better capture the interconnected social and biophysical research gaps on sand dams, fully utilizing the potential of remote sensing in large-scale studies and collecting sand dam cases across the world to create an extensive database to advance evidence-based research on sand dams.

50 years of spring wild turkey harvest in Indiana, 1970–2019

AbstractFifty years (1970–2019) of spring hunting of eastern wild turkeys (Meleagris gallopavo silvestris) has occurred in Indiana, spanning turkey population restoration in the state. A conservative spring harvest structure of a single bird bag, relatively short seasons with a late April opening date was in place for all spring seasons. Herein, we examined trends in state‐wide harvest parameters over time and modeled annual harvest at the county level to examine drivers of harvest. Statewide, harvests, hunter numbers, success rates, and effort initially increased as restoration progressed, with increases in areas open to hunting and days of hunting opportunity. Spring harvests peaked during 2006–2010 and declined 4.7% during 2015–2019. Hunter success peaked during 1998–2002 at 27 ± 0.7% (mean ± SE), then declined to 21 ± 0.6% during 2015–2019. After 1993, spring trips/hunter began to level off with 5 ± 0.46 trips/hunter during 2015–2019. The subadult portion of harvest grew during 1970–1974, stabilized at 30 ± 2.0% during 1976–95, and then declined to 17 ± 1.4% during 2015–2019. Two‐year old males comprised 49% ± 1.5% of the harvest during 1985–2009, then shifted during 2015–2019 to 41 ± 1.5% 2‐yr‐olds and 42 ± 2.8% males ≥3 yr of age. The conservative spring season structures maintained through the restoration era with restricted county fall seasons (1 bird bag either sex, 12‐day firearm initiated post‐restoration in 2005) likely buffered spring harvests from declining production in recent years. We used a 2‐step approach to model annual harvest at the county level. First, we fit a piecewise temporal model with 2 breakpoints to capture the underlying growth of post‐restoration harvest, and its changing slope over time. Second, we added explanatory covariates to the model to explore potential mechanisms for differences in harvest across space and time. Using a generalized linear mixed model, we included variables related to harvest age structure, landscape composition, and restoration effect. Harvests leveled off over time with the best harvest model showing geometric growth for the first 16 years of harvest, followed with moderate growth for 17–39 years of harvest, before leveling off after 40 years under a conservative season structure. The primary model drivers of annual harvest were the proportion of 2‐yr‐olds in the harvest, followed by the number of years between stocking and harvest and the number of turkeys released on the landscape, landscape edge density, and forest clumpiness. Our model results emphasized the importance of production, supported turkey restoration techniques, and demonstrated the suitability of landscapes with diverse land cover types. Ultimately, the availability of quality brood cover along with climatic shifts toward increased precipitation, will influence production trends critical to sustaining current turkey population levels. These changes will in turn, influence the level of 2‐yr‐old males in subsequent spring harvests, hunter success, and the future of the open‐permit structure, depending on the level of hunter demand.

Anti-Overturning Fully Symmetrical Triboelectric Nanogenerator Based on an Elliptic Cylindrical Structure for All-Weather Blue Energy Harvesting

HighlightsThe novel elliptical cylindrical structure (EC) provided an excellent self-stability, high sensitivity in small agitations, and most importantly, a distinctive anti-overturning capability for the EC-triboelectric nanogenerator (EC-TENG).Benefitting from the fully symmetrical design, the EC-TENG could maintain the original output after being overturned under extreme conditions, distinguishing itself from previous TENGs.Two built-in TENGs designed for use in rough seas and tranquil seas improved the collection efficiency for all-weather wave energy.

Realization of an efficient wide-angle solar selective absorber via the impedance matching

Constructing the solar absorber with high omnidirectional absorption has great potential for enhanced solar energy conversion. Although varieties of strategies have been carried out to enhance the solar absorption at the near-normal incidence and achieve the selective solar absorbers (SSAs) with high optical performance, the wide-angle absorber is rarely investigated. Here, we experimentally demonstrated a wide-angle high absorption solar selective absorber configurated with the W–SiO 2 cermet-based quasi-optical cavity structure for effective solar harvesting. It can realize a wideband absorption in the wavelength range of 300–1400 nm at the normal incidence, and maintain the average omnidirectional absorption of ∼95% over the incident angle ranges from 8 to 80°, which ascribes to the impedance matching between the absorber and the free space at a large incident angle. The SSA also demonstrates a large solar absorption of around 70% at the incident angle of 80°. A remarkable temperature increase of ∼40 °C relative to ambient temperature was achieved for the SSA directly exposed to the outdoor sunshine without solar concentration in the subtropical city of Shenzhen. • The W–SiO 2 based quasi-optical cavity absorber demonstrates an angle-insensitive absorption at up to 60° incident angle. • The wide-angle absorption is realized via matching the wave impedance between absorber and incidence medium. • The wide-angle solar absorber demonstrates an omnidirectional absorption of 95% among 8–85°. • This absorber indicates superior stability at 500 °C in vacuum and can maintain at ∼70 °C as directly exposed to outdoor sunlight.

Spherical Triboelectric Nanogenerator Based on Eccentric Structure for Omnidirectional Low Frequency Water Wave Energy Harvesting

AbstractOcean wave energy is a promising green energy source, but it is difficult to exploit on a large scale due to its low frequency and the random uncertainty of its direction. In this study, a spherical eccentric structured triboelectric nanogenerator (Se‐TENG) is designed to harvest omnidirectional low‐frequency water wave energy. Power management circuits (PMM) are designed to optimize the utilization of water wave energy at low frequencies for large‐scale conversion and storage. It is found that the output performance of the Se‐TENG device is influenced by the frequency of the water waves, with the best output performance at a water wave frequency of 2.0 Hz, given that the wave amplitude is 9 cm. It is verified that within the Se‐TENG, the parallel connections of eccentric structured triboelectric nanogenerators (E‐TENGs) are more conducive to energy storage and conversion. In addition, the Se‐TENG used in conjunction with an energy storage device is able to successfully power light‐emitting diodes (LEDs) and digital thermometers, demonstrating its ability to harvest low‐frequency water wave energy in random directions. The unique structure of the Se‐TENG offers an innovative and effective way of gathering blue energy on a large scale.

Modelling of meteorological drought in the foothills of Central Himalayas: A case study in Uttarakhand State, India

In the present study, Meteorological Drought (MD) has been analyzed using India Meteorological Department (IMD) criteria, and Standardized Precipitation Index (PI Standard ) in the foothills of central Himalayan region of Uttarakhand State, India. Rainfall time series at two weather stations, namely Pantnagar and Dehradun stations were selected. For the evaluation of PI Standard method, the moving sums of rainfall data were arranged in monthly time series at the time scales of 1, 3, 6, 12, and 24 months. The rainfall data were analyzed after sequencing it in a time series for testing the different statistical distributions including the Gamma distribution, Normal and Log-Normal distribution. As a result, the Gamma distribution was found most suitable for fitting based on Kolmogorov-Smirnov test at 5% level of significance. Since PI Standard applies the running sum of the rainfall values at different time scales of 1–24 months and more number of variables were used for statistical distributions. The short-term drought monitoring in month of PI Standard -1 and PI Standard -3 was done whereas, for the long-term drought monitoring PI Standard -12 and PI Standard -24 was used for management of water resources. This approach gave better valuation and monitoring of the meteorological drought. The finding is helpful to manage water including rainwater harvesting and water storage structure, irrigation scheduling and yielding the crop. Further, PI Standard were used to predict the drought and submergence conditionsin both stations as a ready reference at 3 or 12 month time scales. The information derived from investigation might be appropriate used for the rainwater harvesting along with proper planning and management of crop planning and water resource storage structure in the area of rainfed and/or drought categories affected by region under the study.

Development of a novel process to select suitable sites for establishing water harvesting structures in Central Gujarat, India

Development of a novel process to select suitable sites for establishing water harvesting structures in Central Gujarat, India

Synergetic metal-semiconductor interaction: Single-atomic Pt decorated CdS nano-photocatalyst for highly water-to-hydrogen conversion

Solar driven water-to-hydrogen conversion is a promising technology for the typical sustainable production mode, so increasing efforts are being devoted to exploit high-performance photocatalytic materials. Cadmium sulfide (CdS) is widely used to prepare highly active photocatalysts owing to its merits of broadband-light harvesting and feasible band structure. However, the slow photo-carriersʹ migration in CdS body structure generally results in high-frequency carriers recombination, which leads to unsatisfied photoactivity. Metallic single-atom surface decoration is an effective method to build the strong metal-support interaction for promotion of photo-carriersʹ migration. Herein, a simple light-induced reduction procedure was proposed to decorate single-atomic Pt on the surface of CdS nanoparticles for highly photocatalytic HER activity. Research showed that the synergetic metal (Pt)-semiconductor (CdS) interaction significantly promoted the body-to-surface (BTS) photo-carriers’ migration of CdS, thereby the high light-to-fuel conversion efficiency (AQY500 nm = 25.70%) and 13.5-fold greater simulated sunlight driven HER rate of bare CdS was achieved by this CdS-Pt nano-photocatalyst. Based on the photo-electrochemical analysis and density functional theory calculations, the remarkably improved HER photoactivity can be attributed to the enhanced light-harvesting, promoted BTS electron migration and reduced reaction energy barriers. This study provides a facile procedure to obtain CdS based photocatalyst with metallic single-atom sites for high-performance HER photocatalysis.

Water Footprint Assessment of Rainfed Crops with Critical Irrigation under Different Climate Change Scenarios in SAT Regions

Semi-Arid Tropical (SAT) regions are influenced by climate change impacts affecting the rainfed crops in their productivity and production. Water Footprint (WF) assessment for rainfed crops on watershed scale is critical for water resource planning, development, efficient crop planning, and, better water use efficiency. A semi-arid tropical watershed was selected in lower Krishna river basin having a 4700 ha area in Telangana, India. Soil and Water Assessment Tool (SWAT) was used to estimate the water balance components of watershed like runoff, potential evapotranspiration, percolation, and effective rainfall for base period (1994 to 2013) and different climate change scenarios of Representative Concentration Pathways (RCP) 2.6, 4.5 and 8.5 for the time periods of 2020, 2050 and 2080. Green and blue WF of rainfed crops viz., maize, sorghum, groundnut, redgram and cotton were performed by considering rainfed, and two critical irrigations (CI) of 30mm and 50mm. It indicated that the effective rainfall (ER) is less than crop evapo-transpiration (ET) during crop growing period under different RCPs, time periods, and base period. The green WF under rainfed condition over different RCPs and time periods had decreasing trend for all crops. The study suggested that in the rainfed agro-ecosystems, the blue WF can significantly reduce the total WF by enhancing the productivity through critical irrigation management using on farm water resources developed through rainwater harvesting structures. The maximum significant reduction in WF over the base period was observed 13–16% under rainfed, 30–32% with 30 mm CI and 40–42% with 50 mm CI by 2080. Development of crop varieties particularly in oilseeds and pulses which have less WF and higher yields for unit of water consumed could be a solution for improving overall WF in the watersheds of SAT regions.

Identifying rainwater harvesting structure sites using MCDM-based GIS approach: a mitigation measure for drought in sub-humid red and lateritic zones of West Bengal, India

Identifying rainwater harvesting structure sites using MCDM-based GIS approach: a mitigation measure for drought in sub-humid red and lateritic zones of West Bengal, India

SITE SUITABILITY ANALYSIS FOR GROUNDWATER MANAGEMENT IN RIVER BASIN OF INDIA

In this study, site suitability analysis for Groundwater management in river basin has been carried out by constructing runoff harvesting structures like percolation pond and check dam. The site suitability for different groundwater recharge is determined by considering spatially varying parameters like sub basin area, runoff potential, slope and fracture pattern. GIS tool used to store, analyse and integrate spatial and attribute information pertaining to drainage, runoff, slope and fracture. The SCS-CN method used to derive runoff potential in terms of runoff coefficient (ratio between the runoff and rainfall) which is classified into three classes, viz., high (&gt;40%), moderate (20–40%) and low (&lt;20%). IMSD specifications for water recharging /harvesting structures, parameters such as effective storage, and rock mass permeability are considered to augment effective groundwater storage. In GIS software, by using an overlay and decision tree concepts, potential water harvesting sites are identified. The derived sites are field investigated for suitability and implementation. The suitability map provides vision in selecting harvesting structures such as anicut, percolation ponds and check dams. In Luni river basin area 38 check dams and seven percolation ponds found were suitable for groundwater recharging and water harvesting.

Integrated piezo-tribo hybrid acoustic-driven nanogenerator based on porous MWCNTs/PVDF-TrFE aerogel bulk with embedded PDMS tympanum structure for broadband sound energy harvesting

In this work, a novel type of acoustic-driven nanogenerator (ANG) that integrates piezoelectric and triboelectric effects is reported for broadband sound energy harvesting. With an internal structure combining beam-like porous multi-walled carbon nanotubes/polyvinylidene fluoride-trifluoroethylene (MWCNTs/PVDF-TrFE) aerogel and polydimethylsiloxane (PDMS) tympanum, the integrated MWCNTs/PVDF-TrFE/PDMS (MCPP) ANG achieves efficient collection of acoustic energy through the enhanced vibration and friction generated internally. Besides, by eliminating the need for a contact separation structure or an external resonator cavity, this design greatly simplifies the structure and contributes to the flexibility and durability of the device. The MCPP ANG, with 20 wt% sodium carboxymethyl cellulose (SCMC), 2 wt% MWCNTs and 5% w/v PDMS, reaches an optimal output of 34.4 V and 1.74 μA under 150 Hz and 115 dB sound stimulation, corresponding to an areal power density of 11.62 mW/m2. It possesses a broad working bandwidth from 110 Hz to 400 Hz, and can directly illuminate 7 light-emitting diodes (LEDs) in series. Employing a novel, simple and effective structural design, the ANG proposed here achieves flexible and stable acoustic collection, offering a promising path toward sound spectrum analysis, noise detection and power supply for various low-power sensors.

Assessment of drought stress in arid olive groves using HidroMORE model

The olive tree is well known for being adapted to the arid conditions of the Mediterranean basin. However, prolonged drought periods which are expected to become more frequent because of climate change could result in severe water stress. In order to map the spatial distribution of drought stress in the olive groves in the arid regions of southeastern Tunisia (governorate of M denine), we made recourse to the HidroMORE model (based mainly on FAO56 ET, NDVI from Sentinel 2 images and other physical parameters) to compute the water balance in a GIS environment. The outputs were compared to in situ soil water content measurements in four selected sites representing the various agro-ecological zones (mountains, piedmont, inner plain and coast) of the study site during the observation period from January 2016 to December 2019. The model outputs performed relatively well (the overall correlation coefficient R2=0.72; index of agreement IA=0.76). The simulation results show that during normal years or average droughts, the water stress is least in the mountain and piedmont zones because of the additional runoff water supplied by the traditional water harvesting structures (Jessour and Tabias) and in the coastal zone, thanks to the higher air humidity and rainfall. In contrast, the olives in the inner plains are the most affected. Nevertheless, in case of severe droughts, the stress is generalised. Thus, the model could be used as a decision tool for prioritizing areas of intervention for drought control and mitigation (supplemental irrigation for trees safeguard, etc.)

Understanding the capacity of key actors and their role in the seed potato systems: The case of Eritrea

Understanding the combined effects of the biophysical, socioeconomic, and institutional components of a seed system can help to improve the effectiveness of seed system interventions. This study examined whether and how institutional factors are contributing to the inadequate supply of quality seed potato in Eritrea and identified where and how bottlenecks within the seed systems might improve the efficacy of seed potato interventions. The research methodology included semi-structured interviews with seed potato system actors, focus group discussions with farmers and local experts, a review of seed potato intervention program reports, farm visit reports, and other literature. The study identified some structural system failures that block the effective functioning of the seed potato intervention. The study recommendations include (i) investment in climate-smart technologies (such as water harvesting structures and new varieties) as well as for electricity supply in the high grades seed production center (ii) shifting the traditional supply-driven approach to a demand driven approach for greater participation of the actors in the seed potato intervention (iii) strengthening the human skill of the actors for greater interaction and collaboration between the different government actors and (iv) developing local strategies to encourage decentralized service provision systems. In the longer term, consideration should be given to greater private sector participation in sourcing and supply of seed and other inputs, even as a pilot-scale activity.

Identifying Suitable Location for Surface Rainwater Harvesting Using GIS and Analytical Hierarchy Process

Rainwater harvesting is old but auspicious technology of sustainable water resource management. In general, the immediate barriers for installing rainwater harvesting techniques is a universal problem which includes the availability of suitable place, initial cost, lack of desired, sound technology etc. The present paper mainly focuses on finding suitable locations for surface rainwater harvesting structures, validation and characterization of these areas using GIS and AHP methods. For validation and characterization of the location google earth and associated thematic layers have been used. The identification of appropriate locations for RWH structures for the Asansol Urban Area in Paschim Burdwan district of West Bengal has been made by utilizing eight different thematic layers in GIS environment. Different GIS layers such as surface elevation, land-use/land-cover, drainage, depression, geology, slope, rainfall and lineament have been used for identifying the suitable location. The result of the study depicts that most of the identified locations as high (10.62%) and very high (4.12%) are suitable for constructing any kind of natural or manmade RWH structure. The present method is comparatively cost effective and time saving which may be convenient for sustainable water resource management planning across the water scarce area in the world.

Assessment of Water Resources in Sana’a Region, Yemen Republic (Case Study)

Yemen is a water-scarce country with inadequate freshwater, considerable groundwater depletion, and a lack of adequate surface water. This study aims to assess water resources and identify the current water situation in Sana’a region, which includes the governorate of Sana’a and the country’s capital, Sana’a city. A variety of data from different sources was collected and analyzed. Remote sensing (RS) and GIS techniques in combination with the Arc Hydro model were utilized. Water demand and supply for domestic and agricultural purposes were estimated. The results show that there is insufficient water to meet the needs of the region’s yearly population growth rates of 3.2 and 4.5% in Sana’a governorate and Sana’a city, respectively. The amount of observed rainfall varies spatially and temporally, ranging between 160 and 367 mm per year. There are 233 water structures, 168 dams, and 65 reservoirs, with a storage capacity of 64.65 and 0.24 Mm3 (million cubic meters), respectively. In Sana’a basin, groundwater abstraction increased significantly from about 25 Mm3 in 1970 to around 330 Mm3 in 2020, while groundwater recharge was about 80 Mm3 in 2020. The estimated water demand for domestic use was in the range of approximately 106–128 and 199–241 Mm3 in Sana’a governorate, whereas in Sana’a city, it was in the range of about 249–302 and 607–737 Mm3 for 2020 and 2040, respectively. The estimated agriculture water demand was between 1.14 and 1.53 Bm3 (billion cubic meters) in 2007, and declined to 801 Mm3 and 1.16 Bm3 in 2018 due to the reduction in the cultivated area by about 33% from 2007 to 2018, which was attributed to a lack of water. The estimated water deficit ranges between 500 and 723 Mm3 during 2007 and 2018. This study concluded that the estimated water supply and demand for the past 12 years from 2007 to 2018 resulted in a supply that was less than the demand in each year, indicating that the available water resources were insufficient to fulfill demand. The significant gap between water supply and demand means withdrawal from the stored groundwater. Thus, groundwater is at high risk. Constructing more water harvesting structures, adopting water conservation, water resource management, and making groundwater artificial recharge are recommended to meet the water demand and conserve non-renewable resources in the coming decades. The results obtained from this study would help decision makers to make appropriate plans to achieve the SDGs in Sana’a region.

Anthracene‐Bridged Sensitizers for Dye‐Sensitized Solar Cells with 37% Efficiency under Dim Light

AbstractNew anthracene‐bridged organic dyes CXC12 and CXC22 are designed and synthesized for high‐efficiency dye‐sensitized solar cells (DSSCs) under dim light. Compared to their parent dye TY6, CXC dyes have additional anthracene‐acetylene group to extend the π‐conjugation of the molecules, resulting in red‐shifted absorption and an enhanced molar extinction coefficient. The absorption spectra of CXC12 and CXC22 with a maximum located at 561 and 487 nm, respectively, match to those of AM 1.5G sunlight and T5 fluorescent light better than that of TY6 (419 nm). It was initially anticipated that long alkoxyl chains introduced to the 2,6‐position of the bridged anthracenyl in CXC12 will retard charge recombination and dye molecular aggregation, and achieve a higher device open‐circuit voltage. However, adsorption of CXC12 molecules on the photoanode dramatically decrease to less than half as compared to that of CXC22 and TY6, resulting in lower short‐circuit current and thus power conversion efficiency. Among these three anthracene‐based dyes, CXC22 has the most appropriate molecular structure for light harvesting and striking the balance between dye loading and molecular aggregation, to exhibit a remarkable power conversion efficiency as high as 37.07% under dim‐light. Therefore, this work shows the potential of anthracene‐bridged organic dyes for indoor photovoltaic applications.

Efficient nano-photonic antennas based on dark states in quantum emitter rings.

Nanoscopic arrays of quantum emitters can feature highly sub-radiant collective excitations with a lifetime exponentially growing with emitter number. Adding an absorptive impurity as an energy dump in the center of a ring shaped polygon allows to exploit this feature to create highly efficient single photon antennas. Here among regular polygons with an identical center absorbing emitter, a nonagon exhibits a distinct optimum of the absorption efficiency. This special enhancement originates from the unique emergence of a subradiant eigenstate with dominant center occupation. Only for nine emitters the sum of coupling strengths of each emitter to all others matches the center to the ring coupling. Analogous to a parabolic mirror the antenna ring then concentrates incoming radiation at its center without being significantly excited itself. Similar large efficiency enhancements, which even prevail for broadband excitation, can also be engineered for other antenna sizes by tailoring the frequency and magnitude of the central absorber. Interestingly, for very small structures a quantum treatment predicts an even stronger enhancement for the single photon absorption enhancement than a classical dipole model. As natural light harvesting structures are often based on ring shaped structures, the underlying principle might be exploited there as well.