Risk Management of Unmanned Aerial Vehicles

This paper presents an efficient risk management model for unmanned aerial vehicles or UAVs. Our proposed risk management establishes a cyclic model with a continuous and iterative structure that is very adaptable to agile methods and all IT-related resources. This model can be used in many applications, but as a case study, we have discussed it for UAVs. The increasing use of UAVs or drones in many fields and the existence of different threats is the main reason to have an efficient risk management method for them. In this paper, we cover risks based on IT-driven assets to decrease the chance of losing any data, failing the equipment or the system, and missing the reputation or credit based on cyclic and iterative flow. Our current risk management model for UAVs or drones is based on qualitative measures and can cover most of IT-based risks

A Novel Memetic Feature Selection Algorithm

Feature selection is a problem of finding efficient features among all features in which the final feature set can improve accuracy and reduce complexity. In feature selection algorithms search strategies are key aspects. Since feature selection is an NP-Hard problem; therefore heuristic algorithms have been studied to solve this problem. In this paper, we have proposed a method based on memetic algorithm to find an efficient feature subset for a classification problem. It incorporates a filter method in the genetic algorithm to improve classification performance and accelerates the search in identifying core feature subsets. Particularly, the method adds or deletes a feature from a candidate feature subset based on the multivariate feature information. Empirical study on commonly data sets of the university of California, Irvine shows that the proposed method outperforms existing methods

Variations in wood density, annual ring width and vessel properties of quercus brantii affected by crown dieback

Funding: This research received no external funding. Acknowledgments: We would like to thank A. Hawasi and S. Soltani for their kind help during this work.Peer reviewedPublisher PD

Variation in wood density and shrinkage in two latex timber clones of rubber trees in different planting densities

Wood density and types of shrinkage were examined in two rubberwood latex timber clones of rubber (Hevea brasiliensis) namely RRIM 2020 and RRIM 2025, planted at densities of 500, 1000, 1500, and 2000 trees/ha, within a trial plot. The mean wood density showed a low descending trend towards high planting densities in both clones. Wood density was significantly and negatively correlated with planting density. The strength of correlation was moderate. The mean longitudinal shrinkage in both clones and tangential shrinkages in clone RRIM 2020 showed no significant difference among planting densities. The tangential (in RRIM 2025), radial and volumetric shrinkages in both clones decreased from low to high planting densities and the differences were more pronounced between densities of 500 trees/ha and 2000 trees/ha. The magnitudes of correlation between these shrinkages and planting density were low. The regression models indicated that wood density could be more ascribed by planting density followed by volumetric shrinkage. This study exhibited low variations in wood density and shrinkages among clones and the respective planting densities; however, RRIM 2025 was more stable than RRIM 2020

Water repellent effect and dimension stability of beech wood impregnated with nano-zinc oxide

The objective of this study was to quantify the influence of zinc oxide nanoparticles (nano-ZnO) on the water repellency and dimensional stability of beech wood. Beech wood blocks were treated with a nano-ZnO solution at four treatment levels (0, 10,000, 20,000, and 40,000 ppm) using a modified dip method. Also, a thermal treatment was performed at 60 and 120°C. After conditioning the samples, water absorption, volumetric swelling, water repellency effectiveness, and anti-shrink/anti-swell efficiency were determined within 24 h of soaking time. The results indicated that the nano-ZnO used for wood modification greatly improved dimensional stability and reduced the hygroscopicity of the wood. In addition, the Fourier-transform infrared spectroscopy (FTIR) analysis suggested a strong interaction between the nano-ZnO and the chemical components of wood. The heat treatment effectively improved the effects of nano-ZnO

Arbuscular mycorrhizal fungal symbiosis with Sorbus torminalis does not vary with soil nutrients and enzyme activities across different sites

Effects of soil chemical properties on arbuscular mycorrhizal fungal (AMF) symbiosis with wild service tree (Sorbus torminalis L. Crantz) were examined for study the rates of root colonization at three forest sites: Kheiroud, Lalis, and Takrin in northern Iran. Soil characteristics including pH, available phosphorus (P), potassium (K), organic matter, total nitrogen, acid and alkaline phosphatase activities, CaCO3, spore density (SD) and AMF colonization of soil and root samples were analyzed. The study sites were investigated in spring and autumn to highlight the effects of soil chemical properties on AMF statues for better nurseries and reforestation management of this rare tree species in forests. Changes in soil pH, P, K, organic matter, total nitrogen, acid and alkaline phosphatase, CaCO3, SD, and AMF colonization of soil and root samples were analyzed at the study sites. K, pH, root colonization, SD and acid phosphatase activity showed no significant differences among sites in spring and autumn, while total nitrogen, P, organic matter and alkaline phosphatase activities showed significant differences among sites and seasons. AMF colonization rates were more than 51% and 32% of roots in spring and autumn, respectively. No correlation between root colonization and soil chemical parameters in spring and autumn were detected. There was no correlation between percentage of AM root colonization and SD nor other soil parameters in spring and autumn. SD and CaCO3 were significantly negatively correlated in spring and autumn. Despite differences in soil characteristics, the results showed that SD and root colonization were not significantly different among the sites. They also showed that wild service trees had strong symbiosis with AMF, while soil properties might not have a significant effect on this symbiosis. Therefore, colonized seedlings can be considered as an appropriated method for reforestation and conservation of this rare tree species

Radial variation of fiber dimenstions, annual ring width, and wood density from natural and plantation trees of Alder (Alnus glutinosa) wood

The aim of this research was to determine radial variations of some wood properties from natural and plantation trees of Alnus glutinosa. Oven-dried wood density (WD), fiber cell features, and annual ring width (ARW) were determined in radial positions of stem at breast height of tree. The results showed that the cultivation methods had significant influence on the fiber length (FL), fiber diameter (FD) and ARW. The effect of interaction between radial position and cultivation methods on anatomical features was not significant, except for cell wall thickeness (CWT). Fiber cell features and WD increased with distance from pith for both cultivations trees. The ARW decreased with increasing the cambial age in both cultivation methods. The average of FL and ARW in plantation trees was higher than those in natural trees. Widest FD was found in natural forest. There were significant relationships between ARW-WD and WD-FD for natural forest and between ARW-WD, ARW-CWT and WD-FL for plantation forest. About 67 % of WD variation in natural and plantation trees were related to FD and ARW, respectively. Due to high FL and ARW, wood from planted trees could be suitable for paper production than wood from natural trees

How Tree Decline Varies the Anatomical Features in Quercus brantii

Funding: This research was funded by Ilam University, grant number 805‑1397‑12.Peer reviewedPublisher PD

Phenotypic and molecular characterization of Neofusicoccum mangiferae, the causal agent of black locust decline

The last few years have seen the rapid and obvious deterioration, wilt, and death of black locust trees in urban and sub-urban areas of Markazi province, Iran. These swift changes are having a serious effect on the landscape and urban forestry. This study was conducted using phenotypic and molecular methods to identify the causal agent of the decline and death of the black locust trees. Pathogen isolation from infested trees was achieved using a potato dextrose agar medium. All the isolates of the fungus produced arthroconidia, making identification using morphological properties possible. Neofusicoccum mangiferae was implicated as the cause of the black locust decline via standard taxonomic criteria for diseased trees. In a pathogenicity test that involved the insertion of a mycelial plug of the respective isolates under the bark, similar symptoms were produced as natural infection. Species classification was confirmed by analysis of the internal transcribed spacer (ITS) sequencing