Small Size Ones Research Articles

Particle sizes crucially affected the release of additives from tire wear particles during UV irradiation and mechanical abrasion

In the environment, tire wear particles (TWPs) could release various additives to induce potential risk, while the effects of particle size on the additive release behavior and ecological risk from TWPs remain unknown. This study investigated the effects and mechanisms of particle sizes (>2 mm, 0.71–1 mm, and <0.1 mm) on the release behavior of TWPs additives under mechanical abrasion and UV irradiation in water. Compared to mechanical abrasion, UV irradiation significantly increased the level of additives released from TWPs. Especially, the additive releasing characteristics were critically affected by the particle sizes of TWPs, manifested as the higher release in the smaller-size ones. After 60 d of UV irradiation, the concentration of antioxidant N-(1,3-dimethylbutyl)-N′-phenyl-p-phenylenediamine (6PPD) reached 10.79 mg/L in the leachate of small-sized TWPs, 2.78 and 5.36 times higher than that of medium-sized and large-sized TWPs. The leachate of the small-sized TWPs also showed higher cytotoxicity. •OH and O2•- were identified as the main reactive oxygen species (ROS), which exhibited higher concentrations and dramatic attack on small-sized TWPs to cause pronounced fragmentation and oxidation, finally inducing the higher release of additives. This paper sheds light on the crucial effects and mechanism of particle sizes in the release behavior of TWPs additives, provides useful information to assess the ecological risk of TWPs.

Study of migration and coalescence of voids driven by electric current stressing in solder interconnects using phase field simulation

Voids in solder interconnects play a crucial role in influencing performance and reliability of solder interconnects, and even lead to the open failure of electronics, especially when high density electric current flowing through the solder interconnects. In this paper, the morphological evolution and migration behaviour of the voids in the solder domain of solder interconnects under electric current stressing is investigated using a developed phase field model. Results show that the surface energy drives the coalescence of voids, and large size voids grow up at the expense of small size ones. The voids migrate along the electric current direction, and the current density distribution and void distribution interactively affect the evolution and migration of the voids. The high magnitude of electric field can potentially induce the open-circuit failure, and the void size is affected by the electric field. Moreover, the voltage across the solder domain increases as the voids migrate to the cathode side. Furthermore, the electric field can promote the void coarsening, and the void migration velocity increases almost linearly with the magnitude of the electric field.

BzATP Activates Satellite Glial Cells and Increases the Excitability of Dorsal Root Ganglia Neurons In Vivo.

The purinergic system plays an important role in pain transmission. Recent studies have suggested that activation of P2-purinergic receptors (P2Rs) may be involved in neuron-satellite glial cell (SGC) interactions in the dorsal root ganglia (DRG), but the details remain unclear. In DRG, P2X7R is selectively expressed in SGCs, which closely surround neurons, and is highly sensitive to 3’-O-(4-Benzoyl) benzoyl-ATP (BzATP). Using calcium imaging in intact mice to survey a large number of DRG neurons and SGCs, we examined how intra-ganglionic purinergic signaling initiated by BzATP affects neuronal activities in vivo. We developed GFAP-GCaMP6s and Pirt-GCaMP6s mice to express the genetically encoded calcium indicator GGCaM6s in SGCs and DRG neurons, respectively. The application of BzATP to the ganglion induced concentration-dependent activation of SGCs in GFAP-GCaMP6s mice. In Pirt-GCaMP6s mice, BzATP initially activated more large-size neurons than small-size ones. Both glial and neuronal responses to BzATP were blocked by A438079, a P2X7R-selective antagonist. Moreover, blockers to pannexin1 channels (probenecid) and P2X3R (A317491) also reduced the actions of BzATP, suggesting that P2X7R stimulation may induce the opening of pannexin1 channels, leading to paracrine ATP release, which could further excite neurons by acting on P2X3Rs. Importantly, BzATP increased the responses of small-size DRG neurons and wide-dynamic range spinal neurons to subsequent peripheral stimuli. Our findings suggest that intra-ganglionic purinergic signaling initiated by P2X7R activation could trigger SGC-neuron interaction in vivo and increase DRG neuron excitability.

A network SIRX model for the spreading of COVID-19

Infectious diseases, such as the current COVID-19, have a huge economic and societal impact. The ability to model its transmission characteristics is critical to minimize its impact. In fact, predicting how fast an infection is spreading could be a major factor in deciding on the severity, extent and strictness of the applied mitigation measures, such as the recent lockdowns. Even though modelling epidemics is a well studied subject, usually models do not include quarantine or other social measures, such as those imposed in the recent pandemic. The current work builds upon a recent paper by Maier and Brockmann (2020), where a compartmental SIRX model was implemented. That model included social or individual behavioural changes during quarantine, by introducing state X, in which symptomatic quarantined individuals are not transmitting the infection anymore, and described well the transmission in the initial stages of the infection. The results of the model were applied to real data from several provinces in China, quite successfully. In our approach we use a Monte-Carlo simulation model on networks. Individuals are network nodes and the links are their contacts. We use a spreading mechanism from the initially infected nodes to their nearest neighbours, as has been done previously. Initially, we find the values of the rate constants (parameters) the same way as in Maier and Brockmann (2020) for the confirmed cases of a country, on a daily basis, as given by the Johns Hopkins University. We then use different types of networks (random Erdős–Rényi, Small World, and Barabási–Albert Scale-Free) with various characteristics in an effort to find the best fit with the real data for the same geographical regions as reported in Maier and Brockmann (2020). Our simulations show that the best fit comes with the Erdős–Rényi random networks. We then apply this method to several other countries, both for large-size countries, and small size ones. In all cases investigated we find the same result, i.e. best agreement for the evolution of the pandemic with time is for the Erdős–Rényi networks. Furthermore, our results indicate that the best fit occurs for a random network with an average degree of the order of 〈k〉≈ 10–25, for all countries tested. Scale Free and Small World networks fail to fit the real data convincingly.

Which firms survive in a crisis? Investigating Gibrat’s Law in Greece 2001–2014

The paper employs a panel dataset of more than 40,000 Greek firms over the period 2001–2014 to examine the size-related patterns of survival and turnover growth before and after the financial and debt crisis that hit Greece in 2010. Our findings suggest that larger-size firms were, in general, more likely to survive in the market than smaller size ones and this relative advantage only grew further during the crisis. However, the rate of growth in turnover for the surviving firms is negatively associated with their size, thus refuting Gibrat’s Law in Greece.

Advanced Beverage Can Crusher Machines: A Review

Beverage Can crushing machine is a device, which is used to compact scrap metal Cansinto small size ones, and, in turn, the Canswould be reused later as new products. Many designs for the Can crushers are applied for such compacting process, some simple and other complicated. This work presents a review study for the advanced or up to date beverage Can crusher machines. Several issues described new designs for the advanced Cans crushing processes are presented in the current study.

A Novel Detector Based on Convolution Neural Networks for Multiscale SAR Ship Detection in Complex Background

Convolution neural network (CNN)-based detectors have shown great performance on ship detections of synthetic aperture radar (SAR) images. However, the performance of current models has not been satisfactory enough for detecting multiscale ships and small-size ones in front of complex backgrounds. To address the problem, we propose a novel SAR ship detector based on CNN, which consist of three subnetworks: the Fusion Feature Extractor Network (FFEN), Region Proposal Network (RPN), and Refine Detection Network (RDN). Instead of using a single feature map, we fuse feature maps in bottom–up and top–down ways and generate proposals from each fused feature map in FFEN. Furthermore, we further merge features generated by the region-of-interest (RoI) pooling layer in RDN. Based on the feature representation strategy, the CNN framework constructed can significantly enhance the location and semantics information for the multiscale ships, in particular for the small ships. On the other hand, the residual block is introduced to increase the network depth, through which the detection precision could be further improved. The public SAR ship dataset (SSDD) and China Gaofen-3 satellite SAR image are used to validate the proposed method. Our method shows excellent performance for detecting the multiscale and small-size ships with respect to some competitive models and exhibits high potential in practical application.

Late Turolian Mesopithecus (Mammalia: Cercopithecidae) from Axios Valley (Macedonia, Greece): earliest presence of M. monspessulanus in Europe

The fossil mammal localities of the Axios Valley (Macedonia, Greece) yielded a rich collection of Mesopithecus remains, which were first described at the beginning of the 1990s. The late Turolian Dytiko localities include several specimens of Mesopithecus, which were originally separated in two size-related forms: the relatively larger-sized M. cf. or aff. pentelicus, and the relatively smaller-sized M. cf. monspessulanus. However, some Dytiko specimens were only partially described, or remained even undescribed because the cranium either was still in connection with the mandible or was markedly deformed. Later, careful cleaning of the materials and their revision based on larger comparative samples indicate that they represent two distinct species: the relatively larger-sized specimens belong to M. pentelicus, while the relatively smaller-sized ones to M. monspessulanus. The Dytiko M. pentelicus has slightly smaller dental dimensions compared to M. pentelicus from Pikermi, indicating a possible trend for size decrease. The Dytiko M. monspessulanus, although close to the typical form of this species, has somewhat larger dimensions. The semi-terrestrial M. pentelicus disappeared at the end of the Miocene, while some of its populations adapted to the wetter and more woody Pliocene habitats, finally giving origin to M. monspessulanus, whose elbow-joint indicates an arboreal lifestyle. M. monspessulanus was widely distributed in Europe, but its remains are very scarce and are all from the Pliocene. Some questionable indications for the presence of M. monspessulanus in the latest Miocene come from some Italian Messinian sites (Gravitelli, Baccinello V3), but this scenario still needs verification. However, even if its presence in some Italian localities was confirmed, the Dytiko M. monspessulanus nonetheless represents the earliest known occurrence of this species in Europe, as the Dytiko fauna is considered as latest Turolian (pre-Messinian, 7.0–6.0Ma).

Alien war: ectoparasite load, diet and temporal niche partitioning in a multi-species assembly of small rodents

Interspecific interactions shape the structure of animal communities, and they rely on a number of multifactorial mechanisms, including e.g. activity rhythms, ectoparasite prevalence, predation pressure and food habits. Despite this, no study has analysed multispecies interactions by combining such a high number of aspects, mostly because the experimental manipulation of studied populations is rarely possible. In our work, we assessed several aspects of interspecific interactions in a rodent assembly composed by three species, by examining diet and temporal- niche partitioning, as well as relevant ectoparasite load and predation pressure, in a natural environment. We analysed stomach contents and ectoparasite load of 78 individuals belonging to all the species, whereas activity rhythms were measured with camera trapping (2200 night-traps, throughout 1 year). Our findings showed that the largest-sized species, i.e. the brown rat Rattus norvegicus was the strongest competitor and may affect diet, temporal behaviour and susceptibility to parasites of smaller-sized ones, i.e. the black rat Rattus rattus and the house mouse Mus domesticus. Larger-sized species showed a broader trophic niche with respect to smaller-sized ones, whereas the smallest species seemed to avoid the largest ones by shifting its temporal activity when the latter was mostly inactive. Larger-sized species may also act as potential predators towards smaller ones, which are also more vulnerable to ectoparasite infestation and to the predation by the only raptor bird present in the study area, the barn owl Tyto alba. We therefore highlight the importance to carry out community-wide studies, to understand interspecific intraguild relationships.

Temporal shifts in the distribution of murine rodent body size classes at Liang Bua (Flores, Indonesia) reveal new insights into the paleoecology of Homo floresiensis and associated fauna

Liang Bua, the type locality of Homo floresiensis, is a limestone cave located in the western part of the Indonesian island of Flores. The relatively continuous stratigraphic sequence of the site spans the past ∼190 kyr and contains ∼275,000 taxonomically identifiable vertebrate skeletal elements, ∼80% of which belong to murine rodent taxa (i.e., rats). Six described genera are present at Liang Bua (Papagomys, Spelaeomys, Hooijeromys, Komodomys, Paulamys, and Rattus), one of which, Hooijeromys, is newly recorded in the site deposits, being previously known only from Early to Middle Pleistocene sites in central Flores. Measurements of the proximal femur (n = 10,212) and distal humerus (n = 1186) indicate five murine body size classes ranging from small (mouse-sized) to giant (common rabbit-sized) are present. The proportions of these five classes across successive stratigraphic units reveal two major changes in murine body size distribution due to significant shifts in the abundances of more open habitat-adapted medium-sized murines versus more closed habitat-adapted smaller-sized ones. One of these changes suggests a modest increase in available open habitats occurred ∼3 ka, likely the result of anthropogenic changes to the landscape related to farming by modern human populations. The other and more significant change occurred ∼60 ka suggesting a rapid shift from more open habitats to more closed conditions at this time. The abrupt reduction of medium-sized murines, along with the disappearance of H. floresiensis, Stegodon florensis insularis (an extinct proboscidean), Varanus komodoensis (Komodo dragon), Leptoptilos robustus (giant marabou stork), and Trigonoceps sp. (vulture) at Liang Bua ∼60–50 ka, is likely the consequence of these animals preferring and tracking more open habitats to elsewhere on the island. If correct, then the precise timing and nature of the extinction of H. floresiensis and its contemporaries must await new discoveries at Liang Bua or other as yet unexcavated sites on Flores.

Particle breakage of granular materials during sample preparation

Particle breakage is commonly observed in granular materials when subjected to external loads. It was found that particle breakage would occur during both sample preparation and loading stages. However, main attention was usually paid to the particle breakage behaviour of samples during loading stage. This study attempts to explore the breakage behaviour of granular materials during sample preparation. Triaxial samples of rockfill aggregates are prepared by layered compaction method to achieve different relative densities. Extents of particle breakage based on the gradings before and after test are presented and analysed. It is found that particle breakage during sample preparation cannot be ignored. Gradings after test are observed to shift away from the initial grading. Aggregates with larger size that appear to break are more than the smaller-sized ones. Irrespective of the initial gradings, an increase in the extent of particle breakage with the increasing relative density is observed during sample preparation.

Phase field simulation of microstructural evolution and thermomigration-induced phase segregation in Cu/Sn58Bi/Cu interconnects under isothermal aging and temperature gradient

Sn-Bi based alloys are widely used as thermal interfacial materials, solders in electronic packaging, thermal fuse and low temperature resistant performance electronic components. However, the inherent tendency of microstructure coarsening and phase segregation in Sn-Bi alloys under thermal loading can easily lead to the inhomogeneous mechanical and thermal response behavior, which can promote crack initiation and expansion near the interface between two major phases (i.e., Bi-rich and Sn-rich phases), and this has brought about serious reliability concern for the above applications and thus attracted increasing attention in recent years. In this study, a phase field model is developed to simulate the microstructural evolution and phase segregation behavior of the eutectic Sn58Bi solder in a line-type Cu/Sn58Bi/Cu interconnect under the condition of isothermal aging and temperature gradient respectively. Results show that the Bi-rich phase and Sn-rich phase distribute inhomogeneously in the Sn58Bi alloy matrix of the solder interconnect during thermal aging; the large size Bi-rich phase particles grow up at the expense of the small size ones, and the value of coarsening exponent n is 0.17. Under temperature gradient, Bi atoms migrate along the direction of the heat flux, and consequently a Bi-rich phase segregation layer forms on the cold end, while a Sn-rich phase area is left on the hot end. The relationship between the temperature gradient distribution and the microstructural characteristics is well revealed. Moreover, the phase segregation under temperature gradient induces the decrease of thermal conductivity, which in turn deteriorates the heat transfer performance of solder interconnects. In addition, comparing the coarsening behavior of the Bi-rich phase under temperature gradient with that during isothermal aging, it is clear that the temperature gradient leads to faster coarsening of the Bi-rich phase, and there is a linear relationship between the mean equivalent radius of the Bi-rich phase and nondimensional time. Finally, the study of thermomigration kinetics of the Bi-rich phase shows that the thickness of the Bi-rich phase segregation layer increases almost linearly with nondimensional time, which is consistent with the theoretical analysis.

Segmentation Refinement of Small-Size Juxta-Pleural Lung Nodules in CT Scans

Background: In order to evaluate the growth rate of lung cancer, pulmonary nodule segmentation is an essential and crucial step. Segmentation of juxta-pleural pulmonary nodule in CT scans, especially small size ones, is still a challenge. Objectives: To better support the following radiomics analysis, this study aims to propose and develop a novel segmentation method for small-size juxta-pleural pulmonary nodules. Materials and Methods: In this study, we investigated and developed a novel approach based on transition region thresholding and chain code analysis to segment juxta-pleural pulmonary nodules. First, we cropped the region of interest (ROI) from the lung CT scans, and enhanced the nodule regions by using an anisotropic diffusion algorithm. Second, to extract the foreground pixels (including the attached chest wall) from ROIs, we applied an adaptive segmentation process by incorporating a threshold segmentation method with transition region analysis. Third, we smoothed the lung contour by using iterative weighted averaging algorithm. Then, we utilized chain code analysis to repair lung parenchyma boundaries. Finally, we obtained the segmentation result by overlapping the extracted foreground with the repaired lung parenchyma mask. Results: To validate the performance of the proposed segmentation approach, we selected 50 juxta-pleural nodules with diameter ranges from 5 mm to 10 mm from Lung Image Database Consortium (LIDC) database. Compared with the ground truth generated by radiologists, we achieved an average overlap rate of 76.93% ± 0.06 with a false positive rate of 13.09% ± 0.09. Conclusion: After comparing and analyzing the segmentation results, we found that our approach outperformed the method reported in other literature. The experimental results demonstrated that our new method is an effective approach to segment small-size juxta-pleural pulmonary nodules accurately.

Analyzing Pellets and Feces of African Royal Terns (Thalasseus maximus albididorsalis) Results in Different Estimates of Diet Composition

A frequently used method to estimate diet composition is based on the identification of fish otoliths present in pellets and feces. However, whether pellets and feces provide similar unbiased estimates of the diet remains poorly understood. The diet of African Royal Terns (Thalasseus maximus albididorsalis) breeding in the Parc National du Delta du Saloum, Senegal, was studied. Prey species composition based on otoliths in freshly regurgitated pellets and a mixture of pellets and feces (excrement) accumulated near nests during the incubation period were compared. Altogether, 59 fish species were identified. Pellets contained far less prey species than excrement. Maximum diet overlap between excrement and pellets varied between 0.34 and 0.43 (mean = 0.36). Differences between minimum and maximum overlap between both sample types were small in all years. Pellets contained almost exclusively large otoliths (widths 3.0–8.5 mm), whereas excrement contained two fractions: large sized ones, identical to those present in the pellets and smaller-sized ones (0.5–3.0 mm) originating from feces. It is hypothesized that large otoliths cannot pass the intestinal tracts of the birds and are therefore regurgitated. Differences in prey species composition in pellets and excrement could potentially be explained by a combination of seasonal changes in availability of prey species and size of otoliths. Neither pellets nor feces alone give an unbiased picture of the diet of African Royal Terns.

Hyperspectral Image Classification With Imbalanced Data Based on Orthogonal Complement Subspace Projection

Conventional classification algorithms have shown great success for balanced classes. In remote sensing applications, it is often the case that classes are imbalanced. This paper proposes a novel solution to solve the problem of imbalanced training samples in hyperspectral image classification. It consists of two parts: one is for large-size sample sets and the other is for small-size sets. Specifically, an algorithm based on the orthogonal complement subspace projection (OCSP) is proposed to select samples from large-size classes, and an algorithm also based on OCSP is proposed to create artificial samples for small-size ones. The impact on representation-based classifiers, i.e., sparse and collaborative representation classifiers and traditional classifiers (e.g., support vector machine), is investigated. Experimental results demonstrate that the proposed solution can outperform other existing solutions in the literature.

Impacto do controle do mexilhão-dourado no custo de produção de tilápia em tanques-rede

Este trabalho avaliou o impacto econômico do controle do mexilhão-dourado na criação de tilápia-do-nilo em tanques-rede de diferentes volumes e escalas de produção. Foram selecionadas 12 pisciculturas situadas no reservatório Ilha Solteira, no rio Paraná (SP/MS), e em Canoas II e Chavantes, no rio Paranapanema (SP/PR). As informações de desembolsos e capital necessários para calcular o custo do controle do mexilhão foram obtidas por meio de questionário apresentado aos piscicultores. Foram contabilizados os gastos com mão de obra, manutenção e depreciação da infraestrutura e equipamentos utilizados na limpeza; manutenção e depreciação adicional dos tanques-rede; e energia elétrica ou combustí­­vel gastos em serviços de limpeza. As empresas de grande porte foram as que tiveram os menores custos incrementais, independentemente do volume dos tanques-rede. A depreciação e a manutenção dos tanques-rede foram os fatores que mais impactaram o custo para o controle de mexilhão, a uma taxa média de 69,89%. O menor custo incremental foi observado nas pisciculturas de grande porte (R$ 0,45 kg fish-1), seguido das de médio e pequeno porte (R$ 1,00 kg fish-1). O impacto econômico médio foi de 11,48% (grande porte), 27,25% (médio porte) e 25,81% (pequeno porte). Considerando o volume dos tanques-rede esse impacto variou entre 7,83% em tanques de 108 m3 e 19,22% em tanques de 6 m3 .&#x0D;

Collusion, profitability and welfare: Theory and evidence

In a differentiated oligopoly model with free entry, the static welfare loss from collusion is larger the lower the entry cost, the larger the market size and the higher the degree of product differentiation. The cartel overcharge is larger the lower the entry cost and the larger the market size, and is independent of the degree of product differentiation. These theoretical results are consistent with evidence from a natural experiment of policy reform, the introduction of cartel law in the UK in the late 1950s. Price-cost margins declined after the breakdown of cartels in low-capital and larger-sized industries relative to capital-intensive and smaller-sized ones. There is weaker evidence of a fall in price-cost margins in consumer good and advertising-intensive relative to producer good and low-advertising industries. Crucially, these effects are not observed for industries that were not affected by the cartel law. A comparison of these findings with evidence on the incidence of collusion suggests that the welfare loss from collusive pricing may often be smaller in industries where cartels tend to form than in those where collusion is more difficult to sustain.

Efficiency and Effectiveness of State Transport Undertakings in India: A DEA Approach

The Indian bus transport industry is dominated by the publicly owned State Transport Undertakings (STUs). Most of the STUs have, over the years, accumulated financial losses. However, since STUs offer their services with a social aim, financial losses faced by them may not be bad per se. For publicly owned organizations, efficiency and effectiveness are more important than mere profitability. This paper attempts to measure the efficiency and effectiveness of fifteen major STUs in India for the period 2003-04 to 2013-14 using Data Envelopment Analysis (DEA). The paper also examines STUs’ scale elasticity and its relationship with firm size. It is found that the STUs operating in the state of West Bengal are not only the least efficient but also the least effective whereas Andhra Pradesh state road transport corporation, which is the largest bus transport operator in the world, is the most efficient and effective operator. In general, there is a strong positive correlation between STUs’ efficiency and their effectiveness. On the other hand, there is a negative relationship between size of the STUs and returns to scale; large size firms are showing decreasing returns to scale whereas small size ones are operating on increasing returns to scale. Therefore, a size correction through mergers, demergers or altering scale of operation, as the case may be, will be economically prudent.

Coauthorship and citation networks for statisticians

We have collected and cleaned two network data sets: Coauthorship and Citation networks for statisticians. The data sets are based on all research papers published in four of the top journals in statistics from $2003$ to the first half of $2012$. We analyze the data sets from many different perspectives, focusing on (a) centrality, (b) community structures, and (c) productivity, patterns and trends. For (a), we have identified the most prolific/collaborative/highly cited authors. We have also identified a handful of "hot" papers, suggesting "Variable Selection" as one of the "hot" areas. For (b), we have identified about $15$ meaningful communities or research groups, including large-size ones such as "Spatial Statistics", "Large-Scale Multiple Testing", "Variable Selection" as well as small-size ones such as "Dimensional Reduction", "Objective Bayes", "Quantile Regression", and "Theoretical Machine Learning". For (c), we find that over the 10-year period, both the average number of papers per author and the fraction of self citations have been decreasing, but the proportion of distant citations has been increasing. These suggest that the statistics community has become increasingly more collaborative, competitive, and globalized. Our findings shed light on research habits, trends, and topological patterns of statisticians. The data sets provide a fertile ground for future researches on or related to social networks of statisticians.

Comparison of Power Requirements: Flapping vs. Fixed Wing Vehicles

The power required by flapping and fixed wing vehicles in level flight is determined and compared. Based on a new modelling approach, the effects of flapping on the induced drag in flapping wing vehicles are mathematically described. It is shown that flapping causes a significant increase in the induced drag when compared with a non-flapping, fixed wing vehicle. There are two effects for that induced drag increase; one is due to tilting of the lift vector caused by flapping the wings and the other results from changes in the amount of the lift vector during flapping. The induced drag increase yields a significant contribution to the power required by flapping wing vehicles. Furthermore, the power characteristics of fixed wing vehicles are dealt with. It is shown that, for this vehicle type, the propeller efficiency plays a major role. This is because there are considerable differences in the propeller efficiency when taking the size of vehicles into account. Comparing flapping and fixed wing vehicles, the conditions are shown where flapping wing vehicles have a lower power demand and where fixed wing vehicles are superior regarding the required power. There is a tendency such that fixed wing vehicles have an advantage in the case of larger size vehicles and flapping wing vehicles have an advantage in the case of smaller size ones.