bluuebunny/crossref_metadata_2025 huggingface dataset:
Frugivorous Birds in Taman Hutan Raya Sultan Thaha Syaifuddin Jambi, Jambi
Authors: Abdillah N K , Mulyani Y A , Rahman D A
Published: July 2020

Frugivorous birds play an important role in forests regeneration by dispersing seeds from the fruit that has been digested by the bird. Taman Hutan Raya Sultan Thaha Syaifuddin is one of the disturbed forests in Jambi Province. In 2015, the province experienced a large fire that nearly devoured its entire area and left very little natural forest. The current land cover includes logged-over secondary forest, after-burnt forest and shrubs, oil palm plantation and some rubber plantation. The objective of this study was to document and compare the species composition of frugivorous birds in the four habitat types. Point counts with a radius of 50 m was used to document the birds. Fifteen sample points with 10 min duration were established in each of the four habitats. Fourteen frugivorous bird species belonging to 6 families were identified. Natural forest held the highest richness and diversity of frugivorous birds (D
Mg
=2.484, H’=2.05), while the oil palm plantation held the lowest richness and diversity (D
Mg
: 0.887, H’=0.74). Sooty-headed Bulbul (Pycnonotus aurigaster) and Orange-bellied Flowerpecker (Dicaeum trigonostigma) were dominant in every habitat.
Relationship between growth sites and content of steroids and sterols from Pikajar (Schizaea digitata)
Authors: Firmanul Arifin Yudi , Suhartono Eko , Hamidah Siti
Published: July 2020

One of the plants known to play a role as a drug in Kalimantan is Pikajar (Schizaea digitata). This species has long been known to ethnic Dayak Meratus in South Kalimantan as traditional medicine. Conservation efforts are not done yet, so this species will be endangered. This study was conducted to determine the characteristic habitat and phytochemical confounds of the root, leave, and flower which it was planted in a different site (natural forest, in-situ and ex-situ). The phytochemical confounds of the root, leave, and the flower was analyzed to use Harborne method. S. digitata tended to grow well on habitats at altitude 164-214 m asl with a pH of 4.3-4.6, N of 0.12-0.15, P of 0.15-0.90mg/100g, C of 2.0-2.2%. It has been successfully cultivated in-situ and ex-situ with growth like natural growth. From a quantitative phytochemical test, there is a difference in the content of secondary metabolites, especially in each part of the plant (roots, leaves, and flowers). The content of steroids and sterols which are a source of treatment for impotence, maintaining stamina, and lumbago shows that the largest part of the leaf contains steroids and sterols compared to roots and flowers, namely 39.5mg/ml, 18.8 mg/ml, 5.2mg/ml respectively. The steroids and sterols content in each growing site shows quite similar (the natural habitat of 21.6mg/ml, in-situ of 22.6mg/ml and ex-situ of 19.3mg/ml).
The characteristics of Pinus mercusii resin productivity flow pattern
Authors: Abdillah E , Muharyani N , Na’iem M
Published: July 2020

Pinus merkusii Jungh et de Vriese belongs to the pine species that grows naturally in Indonesia, particularly in Sumatra: Aceh, Tapanuli and Kerinci. The Perhutani has managed and developed P merkusii as a source for the state revenue. Wood and resin are the most important products of the P merkusii tree.The purpose of this study was to understand the effect of the tree growth based on its resin productivity and its characteristic flow pattern per unit time to support the completion of the project. This study was conducted at KPH Banyumas Barat in March-October 2018. The height and periphery of the trees were the data parameters for the growth evaluation. The resin productivity was evaluated for a year based on the characteristic flow pattern approach by using the drill tapping method on 201 sample trees which was repeated weekly. According to the statistical analysis, the tree’s periphery has a positive effect on the resin productivity whereas the height has a negative one, which means that the cultivation of the pine tree is highly affected by the selected sylviculture. The research showed, by conducting a systematic measurement of the resin productivity of the 201 chosen trees reveals the existence of a good characteristic of resin pattern productivity in 10 individuals trees. The characteristic of resin productivity output pattern sequentially increased with a peak in May-August. This characteristic data is very useful for the Perhutani to optimize the cultivation of the entire P merkusii class for future endeavors.
Economic valuation on carbon sequestration and carbon stocks at green open space based on cost of illness
Authors: Marisha S , Sunarya S , Yustiana Y
Published: July 2020

Green open space is an open area to grow plants that functions as a balancer to urban ecosystems. Unfortunately, the condition of the green open space has declined and impact on human health at a certain level. This study aims to measure the value of ecosystem services for carbon sequestration and stock based on Cost of Illness (COI). The study was conducted at Tegalega, sub area of Bandung City, which is the most populous area in Bandung. Data collection was carried out in two activites. The tree data collection was done by sampling as much as 15%. On the other hand, the health problem data collection was done through interviews with COI method. The results showed that the potential of green open space in absorbing carbon was 126,321.96 kg CO2.hectare−1.year−1 and carbon stocks in current green open space were 47,319 kg.hectare−1. The value of COI from the availability of curent green open space is IDR 288,777,324,987 per year. This value shows the high costs of health that caused by carbon pollution to human in a certain area. The average value of one tree with the service of absorbing and storing carbon is IDR 1,236,566,136.
Financial analysis of coffee from agroforest managed by women farmers group in Tanggamus Lampung
Authors: Nurrochmat N A , Khalifah N N , Kusumadewi D A , Triyantari A , Hidayat F R , Novianti C
Published: July 2020

Coffee (Coffea robusta) is one of the most important products of the community forest (HKm) of Beringin Jaya in Tanggamus Lampung. A women farmers group called KWT Himawari is managing the business of coffee processing. The KWT Himawari was established in 2014 and currently operating a set of coffee processing equipment. This group produces several coffee brands, i.e. Kopi Codot (bat battered coffee), Kopi Merah (red coffee), and Kopi Premium (premium coffee). This study aims to evaluate business feasibility of the coffee processing of KWT Himawari using the financial criteria of Net Present Value (NPV), Benefit Cost Ratio (BCR) and Internal Rate of Return (IRR) within an investment period of 15-years. This study concludes that without any improvement in the business process, the KWT Himawari will potentially lose hundreds million rupiah, indicated by the negative Net Present Value (NPV) of (IDR 181,518,037), Internal Rate of Return (IRR) of (5.245%) and Benefit Cost Ratio (BCR) of 0.781 or less than 1. This study suggests some business improvement to make the women group business feasible. The improved business of coffee processing, so called optimal business model, will make the business profitable with a great potential gain, i.e. NPV of IDR 2,356,763,475, BCR of 1.33 and IRR of 259.57%. The optimal business model can be reached by optimizing production and market that provides several multiplier effects, such as increasing the women’s group income, raising the employment absorption, and stabilizing price of raw coffee from farmers around the forest area.
Clustering Potential Area of Fusarium Oxysporum As A Disease of Garlic
Authors: Purwayoga V , Sitanggang I S
Published: July 2020

The decrease of garlic production can be caused by several factors, one of the main factors is a disease. The main disease of garlic is Fusarium Oxysporm (FO) or known as the rotten base. The decrease in garlic production can be reduced by identifying which areas are likely to be attacked by FO. This study aims to determine clusters of the areas in Central Java Province as the largest producer of garlic in Indonesia which is potentially affected by FO so that this disease can be prevented. This study uses the weather data of 2017 including temperature, humidity, and wind velocity for clustering the potential areas attacked by FO. The algorithm used is K-Means clustering. The best clustering results are obtained at number of clusters K=10, it was obtained from several experiments to determine the number of K. The most potential month for FO breeding is October. The results show that 37 % of areas in October 2017 fall into the minimum category, 63 % FO the area belong to the medium attack category and no one is included in the maximum category due to the fact that daily weather conditions do not fit into that category. October became a potential period because that period was the period with the highest number of regions included in the medium category.
Spatial and Temporal Clustering Analysis of Hotspot Pattern Distribution of Critical Land in Kalimantan, Indonesia
Authors: Kirana AP , Sitanggang IS , Syaufina L , Bhawiyuga A
Published: July 2020

Geographic information systems (GIS) can play a vital function in fire prevention by predicting potential hotspot for fires. This paper presents the analysis of hotspot data in Kalimantan from 2008 to 2018 based on spatial and temporal aspects. Spatiotemporal cluster analysis with Kulldorff’s Scan Statistic (KSS) methods. KSS method is used to explore the spatial temporal patterns. This approach was originally designed to detect clusters and to determine their significance by Monte Carlo replication. the result shows that the provinces with the highest hotspot occurrence cluster are Central Kalimantan and West Kalimantan provinces. Based on critical land area, the cluster distributions of hotspot are dominated in ‘Rather Critical’ and ‘Potential to Critical’ area. Based on land used, the cluster distributions of hotspot are dominated ‘Swamp Shrub’ and ‘Mixed Dry Agriculture Land’. For temporal aspect, the result shows most hotspot occurred in August, September and October. In conclusion, the hotspot detected varied according to year, months and regions. Understanding hotspot patterns enables the allocation of resources for forest fire planning and management. Results showed that the approach is effective for detecting hotspot clusters and cluster accuracy is 91%.
Potential hyperaccumulator plants for sustainable environment in tropical habitats
Authors: Castaňares Edgar , Lojka Bohdan
Published: July 2020

Hyperaccumulators are rare ability of plants to accumulate excessive concentration of elements on roots and shoot tissues without any evidence of physiological stress. However, less research has been conducted in different environmental habitats. Hence, this study was conducted in Mount Magdiwata and Peatland Forest of La Paz, Philippines. The objectives of this research were to identify hyperaccumulator plants as well as analyze soil and plant elemental accumulations. Sampling stations were designated in stratified habitats. Collected soil and plant specimens were analyzed in the laboratory and data were interpreted using SPSS software. Cratoxylum sumatranum (Jack ) Blume, Syngramma alismifolia ( C. Presl ) J.Sm., Mitragyna speciosa Korth, Pneumatopteris laevis ( Mett ) Holtta and Pneumatopteris glabra ( Cope ) Holtt were species that shown hyperaccumulation criterion and had significant accumulation capacity in respective habitats. Manganese had accumulation capacity in the leaves of Mitragyna speciosa Korth above the thresholds level for heavy metal concentrations at 22393 mg/kg−1. Soil element Mg has higher accumulation in the leaves at 5257 mg/kg−1and Fe at 4298 mg/kg−1 both major soil elements had shown significant results. The accumulation capability of this identified species were prospective sources of hyperaccumulator plants onwards to phytoremediation technology to cleanse environmental toxicity.
OSB (Oriented Strand Board Green Building): Utilization of OSB Betung Bamboo (Dendrocalamus asper (Schult. F.) Backer ex Heyne) by Testing Physical and Mechanical Properties to Optimize Eco-Friendly Construction in Indonesia
Authors: Ramatia D , Yosrilrafiq M , Aranti A
Published: July 2020

The National Institute of Building Science (US) states that building materials that come from nature can produce greenhouse gas emissions such as 35% of carbon dioxide, 49% of sulfur dioxide, and 25% of nitrogen oxides. These gasses cause the construction will be unfriendly for the environment, so we need a green construction materials. Bamboo is one of the alternative green constructions because the easiest way to build, elastic and resistant to earthquake, as well as easily repaired in case of damage. OGB (Oriented Strand Board Green Building) is a solution in the use of betung bamboo for green building construction by conducting several tests. This test aims to determine the physical and mechanical properties of betung bamboo by using phenol-formaldehyde (PF) with adhesive contents of 6%, 7%, and 8%. The results showed that the differences in adhesive content of 6%, 7%, and 8% significantly affect the value of density, moisture content, water absorption, thickness, and internal bonding. OGB can be used as a solution for improving eco-friendly building construction in Indonesia.
Spectral Colour Characteristic’s (Red, Green, Blue) of Sick Acacia Mangium Stand
Authors: Abdalla D , Ramdan H , Dungani R
Published: July 2020

Forest protection management are important activities and integrated from the forest resource management system. One of the activities in forest protection is evaluating stand health in a particular forest region. These activities are important because it helps decision making to perform sustainable forest management. Evaluating stand health on a bigger scale needs more cost, time, and manpower. To overcome this obstacle, there is a need for supporting technology. The technology also needs to suffice within the development of remote sensing. flying drones is a suitable technology that could evaluate stand health. This research has the goal to determine the spectral characteristics of A.mangium leaf in order to identify the area and position of sick trees. This research is executed in A.mangium stand at KPH Bogor. The method that is being used is hyperspectral imaging analysis to determine the characteristic of RGB (Red,Green,Blue). Spectral analysis is sampled from 85 trees on 7 plot at site 23B RPH Maribaya BKPH Parung Panjang KPH Bogor using simple random sampling. The result of this research shows that trees in healthy condition, sick condition, and the dead condition has different spectral RGB value. RGB value for healthy trees is 121-149(B1),167-189(B2), 120-142(B3). For sick trees the RGB value is 151-165(B1), 183-205(B2), 145-165(B3). For dead trees the RGB values are 192-202(B1), 202-212(B2), 167-199(B3). As trees condition worsen, the RGB value increases. The pattern of RGB band composition is similar but has different values. This indicates the changing process of leaf color from healthy to sick. On the other hand the interval of RGB band is small enough to notice there is a difference in the color of the tree’s status. This research shows that spectral analysis from drone image could be used to analyze forest’s stand health
Alstonia scholaris R.Br Bark Extract as Diabetes Medicine
Authors: Zuraida  , Sulistiyani
Published: July 2020

Pulai (Alstonia scholaris R.Br) is one of leading vegetation for forest plantations. Besides being a timber forest product, it has high value on non-timber forest product such as animal feed, black board, chewing gum, and medicine. Utilization of pulai leaves as medicine such as for wounds, intestinal worms, malaria, hypertension, and heart disease had been reported, but research on pulai bark as antidiabetes is still limited. This study aimed to study phytochemical compound, toxicity, and in vitro inhibition activity of α-glucosidase enzyme of pulai bark crude extrac as antidiabetes. Pulai bark extraction done by maceration method using 96% ethanol resulted in 4.39% yield. Phytochemical test contained flavonoid, saponin, alkaloid and tannin. Pulai crude extract toxicity tested by Brine Shrimp Lethality Test (BSLT) method, resulted in LC50 value of 461 μg/mL indicated moderate toxicity. Testing of in vitro inhibition activity of α-glucosidase enzyme resulted in IC50 value of 152.99 μg/mL. Based on the research, 96% of ethanol crude extract pulai bark had bioactivity, and flavonoids, alkaloids and tannins content appeared to have important role in inhibition activity of α-glucosidase enzyme.
Spatiotemporal Pattern Distribution of Drought Area using MODIS Vegetation Health Index. Case Study: Paddy Field in East Java, Indonesia
Authors: Kirana AP , Ririd ARTH , Ariyanto R , Amalia EL , Bhawiyuga A
Published: July 2020

Drought is the main natural disasters in Indonesia. Study of spatial and temporal drought pattern distribution is great significance for disaster prevention and mitigation. Agricultural drought assessment was used to monitor agricultural sustainability, particularly in East Java as the national centre for agricultural production in Indonesia This study aimed to detect the spatial and temporal pattern of agricultural drought using Vegetation Health Index (VHI) and illustrated drought characteristics in East Java, Indonesia during 2017-2018. In this research, we use LST and EVI data from MODIS Terra satellite data. We used LST for calculating TCI, and EVI for calculating VCI. VHI were obtained by TCI and VCI score. The result showed that all drought-affected areas were experienced by moderate droughts. Bojonegoro, Magetan and Gresik district has the highest drought level compared to another district in East Java. Drought area increased significantly in September to October, which is dry season in Indonesia and cover 69.13% of agricultural area.
Cooling effect to mitigate Urban Heat Island by Pterocarpus indicus, Swietenia macrophylla and Samanea saman In Bandung, West Java Indonesia
Authors: Ihsan F , Rosleine D
Published: July 2020

Urban Heat Island (UHI) has been detected in Bandung since 2001 and it can be mitigated by planting trees such as Pterocarpus indicus (angsana), Swietenia macrophylla (mahogany), and Samanea saman (trembesi). This research was conducted to measure temperature reduction by those road side trees at seven locations. Parameters were tree characteristics including shape and area of canopy, Plant Area Index (PAI), and leaf morphology (shape and arrangement), air temperature, relative air humidity, transmissivity, and surface temperature. Microclimate and edaphic data were measured in sunny day or partly cloudy. Data were analyzed using One-way ANOVA (Kruskal-Wallis test) to clarify significance differences among parameters in each tree species and measured reduction of discomfort index (dDI%). Air temperature in open area is 33.81±2.32°C, while surface temperature is 37.29±6.63°C. Result shows that trees have varies ability to decrease air and surface temperature. The highest reduction of air (A) and surface (S) temperature is shown by S. saman (A=3.80±1.21°C and S=10.49±2.84°C), then followed by S. macrophylla (A=3.10±1.94°C and S=5.64±5.51°C), and P. indicus (A=2.28±1.73°C and S=5.26±4.30°C). S. saman which has wide canopy with moderate leaf density can reduce air and surface temperature effectively, followed by S. macrophylla with narrow canopy and high leaf density; and P. indicus with narrow canopy with low leaf density. Thus, tree character with broad canopy and dense leaves such as S. saman can be recommended as shading tree to mitigate UHI in urban areas.
Household Captive Breeding: Women Empowerment in Wildlife Conservation
Authors: Sunkar A , Ma’rufi N , Masy’ud B
Published: July 2020

Conservation activities involving women are often less addressed. Considering site-level conservation is very important, women have higher opportunities to be engaged in household conservation activities due to higher leisure time. Women also have nurtured and caring personalities, variables necessary for wildlife survival in captive breeding. This study analysed protected bird captive breeding profiles and determined the roles of women involved and their impacts on the survival of the birds in captivity. The study was conducted from January to April 2017 at 90 protected bird captivities with 122 respondents comprised of 24 breeders in Bogor City and District, and 98 in Klaten District. Harvard gender analysis was used to analyse the roles of women, while qualitative analysis was used to determine the profiles of the captive breeding and the women involved. The relation between women’s involvement and the percentage of bird survival was analysed using t-test with two independent samples of a 5% standard error. The percentage of women involved in captive breeding was between 34.17 to 56.25%. Women contributed to the family’s income both as workers (35-100%) and owners (30-100%). They are 31-40 years of age, hold high school diplomas, married with the youngest child in elementary-junior high school. At the household scale, women contributed to 68.76% of the total breeding activities. Results showed that the percentage of birds’ surviving at household captive breeding is higher under the care of women. This study justified the importance of involving women in wildlife conservation, which would contribute to decreased forest and environmental degradation.
Citizen science networks for waterbird monitoring: Case study of the Asian Waterbird Census in Indonesia
Authors: Gumilang R S , Mardiastuti A , Kusrini M D , Noor Y R
Published: July 2020

Citizen science is a public participation research involving citizen participation, whose outcomes are often advancements in scientific research and increase the public’s understanding. This study is aimed to identify the characteristics of volunteers who joined the Asian Waterbird Census (AWC), a part of the long-term global annual monitoring initiative by Wetlands International. Data were gathered through analysis of documentations (year 2015-2019), observation, and deep interview. The number of participants has increased, with the highest was 379 persons in 2019 (an average of 233 persons/year), with half comprised of university graduates (Bachelor or above). There were 5 types of groups involved in AWC: student/universities (34%), NGOs (27%), individuals (19%), government employees (16%), and private sectors (3%). Females’ participation was quite high (43%). About 18% of participants and 44% of the groups, have been joining AWC at least twice, indicating that AWC was an interesting activity. Reasons to join were identified as: increasing personal values, personal scientific development, strengthening social relationships/networks, recreational, and develop a career. Information on AWC schedules was obtained mostly through social media Whatsapp (35%) and Facebook (32%), the organizer (i.e. Wetlands International Indonesia; 37%) and participants’ networks (37%). About 73% of the participants were able to observe less than 100 bird species. Participants’ constraints during the AWC were ability of bird identification, limitation of proper equipment, and low accessibility to potential observation sites. Our study indicated that understanding the characteristics of participants might help to improve the citizen science program, as well as to recruit and retain volunteers.
Effect of 6-BAP application on shoot production of Melaleuca alternifolia seedlings
Authors: Amelia Z R , Supriyanto  , Wulandari A S
Published: July 2020

Melaleuca alternifolia (tea tree) is one of the families of Myrtacea, which produces essential oils from their leaves, called tea tree oil (TTO) that is used as ingredients for cosmetics, antiseptics and pesticides. TTO leaves production of M. alternifolia plants can be increased by stimulating the growth of new shoots using 6-BAP hormone. The purpose of this study was to obtain appropriate dosage of 6-BAP to induce shoots in M. alternifolia seedlings. This research was conducted at the Dramaga Permanent Nursery in Bogor for 6 weeks from July-Agustus 2019 with M. alternifolia seedlings originating from grafts over 4 months old. Completely randomized design (CRD) with different 6-BAP concentration treatments in 5 replicates was used. The 6-BAP (benzyl amino purine) with a concentration of 5 ppm, 10 ppm, 15 ppm, 20 ppm and without hormone (as control) were sprayed on the leaves and stem. The results showed that 6-BAP affected shoot length and number of leaves. Spraying with 5 ppm 6-BAP dose increased the length of shoots and the number of leaves after 6 weeks of application amounting to 1.9% and 11.4%, respectively.
Application of the method of dynamic programming for solving the optimal unit commitment problem in distribution networks with local distributed generation
Authors: Dimishkovska Natasha , Iliev Atanas
Published: July 2020

The continuous growth of communities leads to an increase in electrical energy usage. Besides the technological advance of power systems, still, there are outages which lead to an interruption in the power supply. The implementation of distributed generation provides usage of the local renewable energy sources for satisfying local power needs which in good manner complexes the distribution networks. However, because the distributed energy resources depend on the weather conditions, the islanded work is not quite reliable. Grid-connected distributed energy resources have enhanced power supply reliability. In this paper, a dynamic programming model is used for the optimisation of power generation by the local distributed energy resources. Assuming the distributed energy resources have storage systems, the model takes into account the battery charge at the moment and the availability of the distributed energy resources depending on the weather conditions and whether is day or night. It is assumed that the distributed energy resources have equal power capacities. Case study reviews a low voltage distribution network with plenty of distributed energy resources from different renewable energy sources implemented and a cluster of household consumers.
On the use of blockchain technologies in smart home applications
Authors: Pazhev G , Spasov Gr , Shopov M , Petrova G
Published: July 2020

The paper presents an implementation of a smart home architecture with two gateways based on collaboration of blockchain technology and Internet of Things (IoT) Message oriented middleware (MOM) architecture for management of internal home appliances. A basic overview of IoT MOM, MQTT (Message Queue Telemetry Transfer) protocol and blockchain architectures is made and the key characteristics and consensus algorithms are presented. Some challenges and the Ethereum smart contracts concept of the blockchain technology are discussed.
Gamification of courses in the e-learning environment
Authors: Gachkova Mariya , Somova Elena , Gaftandzhieva Silvia
Published: July 2020

The paper presents a study in the field of gamification of learning, in particular – in structural gamification. The four-stages cyclic (Learning – Evaluation – Rewarding – Ranking) gamification learning model is proposed. The used gamified elements (level, story/history, challenge, team, time frame, game progress, status (avatar), bonus, badge, reward, hidden treasures, combo and leaderboard) with their impact to the learner’s motivation are explained. Two plug-ins are designed, developed and tested with real users. One of the plug-ins changes the design of the learning course in game-like view, while the other ranks the students in a leaderboard with their avatars, according to their course progress. The short explanation of the experiment with learners is done and part of the statistical results from the conducted survey in five areas (practical applicability; motivation; design and accessibility; interactivity and communication; and intelligibility) are shown.
Dynamical stresses in the high class wind turbine blades caused in nonhomogeneous nonstationary wind field. Part 1 Dynamical model
Authors: Kralov I , Genov J , Angelov I
Published: July 2020

The wind turbines of a high class are with considerable sizes. For this reason, the consideration of the fluid field as a homogeneous when performing the aerodynamic analysis is not quite correct. In addition, due to the gusts and horizontal turbulence, the wind field is also nonstationary. All this causes dynamic, time-varying loads and fatigue. The determination of these loads is a major aim of this publication. The turbine blades are considered as Euler-Bernoulli beams under the impact of the aerodynamic thrust and torque forces as well as from this of the centrifugal force. The finite element method is applied to solve the partial differential equations describing the model under consideration. Two-node elements with four degrees of freedom for each node and a cubic, polynomial approximation of modal shapes were used. The deformations are relatively small in the separated finite elements and this makes it possible to apply the superposition principle.
Application of multi-axis force/torque sensor system for experimental study of small unmanned aerial vehicles propulsion systems – Preliminary results
Authors: Serbezov V , Panayotov H , Todorov M , Penchev S
Published: July 2020

The experimental evaluation of the performance of small propellers plays important role in the process of multicopter UAV design perfection. This paper presents a small UAV propeller test stand, based on a multi-axis Force/Torque sensor system. The system makes possible to measure the thrust, torque and the pitching moment or lateral force (when in oblique flow) of the tested propeller. The data processing of the experimental results is discussed. Results for static, axial flow and oblique flow conditions are presented. Some conclusions about the measurement methodology are drawn. The results verify that the test bench has good accuracy and is easy for operation.
Aerodynamic testing of rotors and propellers for small unmanned aerial vehicles at Technical University - Sofia
Authors: Panayotov F , Serbezov V , Todorov M
Published: July 2020

The recent massive introduction of small unmanned aerial vehicles (UAVs) brought the problem of absence of reliable aerodynamic data and models for propulsion systems that work at low Reynolds numbers. At the same time the new capabilities of modern measuring equipment permit detailed experimental investigations of the aerodynamic characteristics of such systems. This paper presents the results of work in this direction, carried out at, or with serious contribution of the Department of Aeronautics at Technical University of Sofia. Two test benches are presented. The first one is for static testing of small helicopter rotors. It is designed also with provisions for installation in suitable wind tunnels. The second one is a test stand for evaluation of electric power plants for unmanned aircraft vehicles. It can be used statically, or may be installed on the roof of an automobile for mobile testing. As an illustration experimental results are given for a specific model helicopter rotor and a small airplane propeller.
Use of modern software solutions and systems for analysis and reconstruction of road accidents
Authors: Damyanov I S
Published: July 2020

This study examines the possibilities of investigating a road accident and provides initial data for the reconstruction of road accidents using photogrammetric techniques. Compared to the conventional practice of road accident reconstruction, photogrammetry saves time, money and is an effective method for investigating road accidents. The use of unmanned aerial vehicles - UAVs and mapping software enables the collection of collecting the data needed to investigate, analyze and reconstruct road accidents. The measurement results can be considered as initial information for a technique for repairing damage analysis. The study shows that photogrammetry has an increasing potential for application in the investigation and recovery of road accidents.
Crack propagation evaluation using virtual prototyping techniques
Authors: Kamberov K H , Ivanov Ts T , Zlatev B N
Published: July 2020

A methodology for crack propagation using virtual prototyping (VP) is demonstrated. It is based on a classical approach to assess crack propagation, improved with finite element analysis tools. It enables to examine in detail all aspects of crack formation and to evaluate the probability of its occurrence. Performed demonstration is based on Al2O3 substrate laser scribing process and its assessment in direction of possible crack occurrence. Presented study gives basic directions on application of virtual prototyping in crack initiation and propagation prediction. This approach gives the opportunity to monitor various parameters as stresses and to predict influence of various design changes over examined physical process output parameters.
Classification of parts used in mechatronic products and produced by permanent-mold casting methods
Authors: Zaharinov V , Malakov I , Nikolov S , Dimitrova R , Stambolov G
Published: July 2020

The paper presents the results from a research on parts used in mechatronic products and produced by the permanent-mold casting methods of gravity die casting and die casting. An overview and analysis of different definitions for mechatronic systems and examples of mechatronic products is made. As a result, a new definition for a mechatronic product is proposed. Various classifications of mechatronic products are analysed and deemed too general for the purposes of the current research. Permanent-mold casting methods are analysed and their advantages and disadvantages are pointed out. Arguments as to why these methods are suitable for producing mechatronic product parts are given. Based on the proposed definition for mechatronic product, the analysed classifications, and the overview of the permanent-mold casting methods a new classification is proposed. The classification is used for classifying permanent-mold cast parts used in mechatronic products. The parts are classified in six groups with regard to their application in the mechatronic product. In addition, the classification gives information regarding permanent-mold casting method used, material, and mechatronic product that includes the part.
Corrosion behaviour of aluminium alloys EN AW-6026 and EN AW-6082 in a sulphuric acid medium
Authors: Kamarska Kalina
Published: July 2020

The corrosion behaviour of aluminium alloys EN AW-6026 and EN AW-6082 in 0,1 M and 1 M sulphuric acid solutions at different temperatures has been investigated by using gravimetric techniques and a digital microscope. The study revealed that the corrosion rate increases with higher temperature and concentration of H2SO4. The surface attack increased with the increasing of the concentration of sulphuric acid and the temperature. Alloys EN AW-6026 and EN AW-6082 have a higher corrosion resistance at 25 °C.
Analysis of significant floods in Bulgarian Danube region till 2010 y
Authors: Velichkova Rositsa
Published: July 2020

Floods in Bulgaria are natural hazards that occur often and make huge damage. In current work the significant floods for Danube region are discussed. An analysis for the period till 2010 is made. The rivers which cause most damages in that region are shown.
Convection-induced singularity suppression in the Keller-Segel and other non-linear PDEs
Authors: Iyer Gautam , Xu Xiaoqian , Zlatoš Andrej
Published: July 2020

In this paper we study the effect of the addition of a convective term, and of the resulting increased dissipation rate, on the growth of solutions to a general class of non-linear parabolic PDEs. In particular, we show that blow-up in these models can always be prevented if the added drift has a small enough dissipation time. We also prove a general result relating the dissipation time and the effective diffusivity of stationary cellular flows, which allows us to obtain examples of simple incompressible flows with arbitrarily small dissipation times.

As an application, we show that blow-up in the Keller-Segel model of chemotaxis can always be prevented if the velocity field of the ambient fluid has a sufficiently small dissipation time. We also study reaction-diffusion equations with ignition-type nonlinearities, and show that the reaction can always be quenched by the addition of a convective term with a small enough dissipation time, provided the average initial temperature is initially below the ignition threshold.
Positivity sets of supersolutions of degenerate elliptic equations and the strong maximum principle
Authors: Birindelli Isabeau , Galise Giulio , Ishii Hitoshi
Published: July 2020

We investigate positivity sets of nonnegative supersolutions of the fully nonlinear elliptic equations

F
(
x
,
u
,
D
u
,

D
2

u
)
=
0

F(x,u,Du,D^2u)=0

in

Ω
\Omega

, where

Ω
\Omega

is an open subset of

R

N

\mathbb {R}^N

, and the validity of the strong maximum principle for

F
(
x
,
u
,
D
u
,

D
2

u
)
=
f

F(x,u,Du,D^2u)=f

in

Ω
\Omega

, with

f
∈

C

(
Ω
)

f\in \mathrm {C}(\Omega )

being nonpositive. We obtain geometric characterizations of positivity sets

{
x
∈
Ω

:

u
(
x
)
>
0
}

\{x\in \Omega \,:\, u(x)>0\}

of nonnegative supersolutions

u
u

and establish the strong maximum principle under some geometric assumption on the set

{
x
∈
Ω

:

f
(
x
)
=
0
}

\{x\in \Omega \,:\, f(x)=0\}

.
Singularity formation for the fractional Euler-alignment system in 1D
Authors: Arnaiz Victor , Castro Ángel
Published: July 2020

We study the formation of singularities for the Euler-alignment system with influence function

ψ
=

k
α

|

x

|

1
+
α

\psi =\frac {k_\alpha }{|x|^{1+\alpha }}

in 1D. As in [Commun. Math. Sci. 17 (2019), pp. 1779–1794] the problem is reduced to the analysis of a nonlocal 1D equation. We show the existence of singularities in finite time for any

α
\alpha

in the range

0
>
α
>
2

0>\alpha >2

in both the real line and the periodic case and with just a point of vacuum.
Log BPS numbers of log Calabi-Yau surfaces
Authors: Choi Jinwon , van Garrel Michel , Katz Sheldon , Takahashi Nobuyoshi
Published: July 2020

Let

(
S
,
E
)

(S,E)

be a log Calabi-Yau surface pair with

E
E

a smooth divisor. We define new conjecturally integer-valued counts of

A

1

\mathbb {A}^1

-curves in

(
S
,
E
)

(S,E)

. These log BPS numbers are derived from genus 0 log Gromov-Witten invariants of maximal tangency along

E
E

via a formula analogous to the multiple cover formula for disk counts. A conjectural relationship to genus 0 local BPS numbers is described and verified for del Pezzo surfaces and curve classes of arithmetic genus up to 2. We state a number of conjectures and provide computational evidence.
Torsion points of order 2𝑔+1 on odd degree hyperelliptic curves of genus 𝑔
Authors: Bekker Boris , Zarhin Yuri
Published: July 2020

Let

K
K

be an algebraically closed field of characteristic different from

2
2

, let

g
g

be a positive integer, let

f
(
x
)
∈
K
[
x
]

f(x)\in K[x]

be a degree

2
g
+
1

2g+1

monic polynomial without multiple roots, let

C

f

:

y
2

=
f
(
x
)

\mathcal {C}_f: y^2=f(x)

be the corresponding genus

g
g

hyperelliptic curve over

K
K

, and let

J
J

be the Jacobian of

C

f

\mathcal {C}_f

. We identify

C

f

\mathcal {C}_f

with the image of its canonical embedding into

J
J

(the infinite point of

C

f

\mathcal {C}_f

goes to the zero of the group law on

J
J

). It is known [Izv. Math. 83 (2019), pp. 501–520] that if

g
≥
2

g\ge 2

, then

C

f

(
K
)

\mathcal {C}_f(K)

contains no points of orders lying between

3
3

and

2
g

2g

.

In this paper we study torsion points of order

2
g
+
1

2g+1

on

C

f

(
K
)

\mathcal {C}_f(K)

. Despite the striking difference between the cases of

g
=
1

g=1

and

g
≥
2

g\ge 2

, some of our results may be viewed as a generalization of well-known results about points of order

3
3

on elliptic curves. E.g., if

p
=
2
g
+
1

p=2g+1

is a prime that coincides with

char
⁡
(
K
)

\operatorname {char}(K)

, then every odd degree genus

g
g

hyperelliptic curve contains at most two points of order

p
p

. If

g
g

is odd and

f
(
x
)

f(x)

has real coefficients, then there are at most two real points of order

2
g
+
1

2g+1

on

C

f

\mathcal {C}_f

. If

f
(
x
)

f(x)

has rational coefficients and

g
≤
51

g\le 51

, then there are at most two rational points of order

2
g
+
1

2g+1

on

C

f

\mathcal {C}_f

. (However, there exist odd degree genus

52
52

hyperelliptic curves over

Q

\mathbb {Q}

that have at least four rational points of order 105.)
On the number of tame concealed convex subcategories in cycle-finite algebras
Authors: Malicki Piotr
Published: July 2020

We prove that for every cycle-finite algebra

A
A

the number of pairwise different tame concealed convex subcategories of the convex hull of the support of an indecomposable

A
A

-module is bounded by

3
3

.
The first cohomology, derivations, and the reductivity of a (meromorphic open-string) vertex algebra
Authors: Huang Yi-Zhi , Qi Fei
Published: July 2020

We give a criterion for the complete reducibility of modules satisfying a composability condition for a meromorphic open-string vertex algebraVVusing the first cohomology of the algebra. For aVV-bimoduleMM, letH^∞1(V,M)\hat {H}^{1}_{\infty }(V, M)be the first cohomology ofVVwith the coefficients inMM, which is canonically isomorphic to the quotient space of the space of derivations fromVVtoWWby the subspace of inner derivations. LetZ^∞1(V,M)\hat {Z}^{1}_{\infty }(V, M)be the subspace ofH^∞1(V,M)\hat {H}^{1}_{\infty }(V, M)canonically isomorphic to the space of derivations obtained from the zero mode of the right vertex operators of weight11elements such that the difference between the skew-symmetric opposite action of the left action and the right action on these elements are Laurent polynomials in the variable. If<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="ModifyingAbove upper H With caret Subscript normal infinity Superscript 1 Baseline left-parenthesis upper V comma upper M right-parenthesis equals ModifyingAbove upper Z With caret Subscript normal infinity Superscript 1 Baseline left-parenthesis upper V comma upper M right-parenthesis">H^∞1(V,M)=Z^∞1(V,M)\hat {H}^{1}_{\infty }(V, M)= \hat {Z}^{1}_{\infty }(V, M)for everyZ\mathbb {Z}-gradedVV-bimoduleMM, then every leftVV-module satisfying a composability condition is completely reducible. In particular, since a lower-boundedZ\mathbb {Z}-graded vertex algebraVVis a special meromorphic open-string vertex algebra and leftVV-modules are in fact what has been called generalizedVV-modules with lower-bounded weights (or lower-bounded generalizedVV-modules), this result provides a cohomological criterion for the complete reducibility of lower-bounded generalized modules for such a vertex algebra. We conjecture that the converse of the main theorem above is also true. We also prove that when a grading-restricted vertex algebraVVcontains a subalgebra satisfying some familiar conditions, the composability condition for grading-restricted generalizedVV-modules always holds and we need<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="ModifyingAbove upper H With caret Subscript normal infinity Superscript 1 Baseline left-parenthesis upper V comma upper M right-parenthesis equals ModifyingAbove upper Z With caret Subscript normal infinity Superscript 1 Baseline left-parenthesis upper V comma upper M right-parenthesis">H^∞1(V,M)=Z^∞1(V,M)\hat {H}^{1}_{\infty }(V, M)= \hat {Z}^{1}_{\infty }(V, M)only for everyZ\mathbb {Z}-gradedVV-bimoduleMMgenerated by a grading-restricted subspace in our complete reducibility theorem.
Impact of Apoidea (Hymenoptera) on the World’s Food Production and Diets
Authors: Lorenzo-Felipe Israel , Blanco Carlos A , Corona Miguel
Published: July 2020

Bees and some wasp species of the superfamily Apoidea pollinate most of the crops used for food and feed, producing different impacts on agricultural production. Despite the considerable importance of Apoidea, the relevance of this group’s impact on global crop production and human diets is controversial. To measure the pollination effect of these insects on crop production, factors such as the myriad of agricultural practices, different crop varieties, fluctuating pollinators’ densities, constantly changing environmental conditions, and demands for food items in a diverse diets must be considered. An ‘Apoidea impact factor’ (AIF), a value calculated taking into consideration the effect of this superfamily on enhancing crop production through pollination, the diversity of crops in a given area, the area planted by specific crops, and agricultural output, was calculated for 176 agricultural crops. Consistently with previous estimations, our results show that Apoidea have a direct impact on 66% of the 128 most important agricultural crops consumed in the world. However, the analysis of the impact of Apoidea on global production and human consumption revealed a different perspective: Apoidea pollination affects only 16% of the total tonnage output, 14% of the cultivated area, and 9% of the kilocalories consumed. Because 25 of the most cultivated crops in the world do not require, or are slightly affected by Apoidea pollination, and these plants grow in 84% of the world’s cropland, constituting 50% of the world’s diet, and 89% of the kilocalories consumed by peoples around of the world, the AIF at the world level is reduced to 11% of food consumed, and 6% of the kilocalories. The AIF, when applied to a small geographical scale, for example, the municipality or county level rather than country or state level, becomes more useful identifying areas where bees and wasps have greater impact in agriculture. In this report, we update the widely popular quote ‘One out of every three bites of food we eat is a result of pollinators like honey bees’ to a more accurate one: ‘nearly 5% of the food we eat, and about 10% of the calories we burn have a direct relationship with Apoidea pollination’. This new estimate does not diminish the need for pollinators for many of the world’s most nutritious foods, but merely suggests that these foods do not provide an extensive part of the human diet. The AIF can be used to identify specific areas where these pollinators have greater impact and direct conservation efforts directly into them. This approach can serve as a better estimate of the role of these pollinators in our food, using data-driven arguments.
Discovery and Mediation Analysis of Cross-Phenotype Associations Between Asthma and Body Mass Index in 12q13.2
Authors: Salinas Yasmmyn D , Wang Zuoheng , DeWan Andrew T
Published: July 2020

Twin studies suggest that shared genetics contributes to the comorbidity of asthma and obesity, but candidate-gene studies provide limited evidence of pleiotropy. We conducted genome-wide association analyses of asthma and body mass index (BMI; weight (kg)/height (m)2)) among 305,945 White British subjects recruited into the UK Biobank in 2006–2010. We searched for overlapping signals and conducted mediation analyses on genome-wide-significant cross-phenotype associations, assessing moderation by sex and age at asthma diagnosis, and adjusting for confounders of the asthma-BMI relationship. We identified a genome-wide-significant cross-phenotype association at rs705708 (asthma odds ratio = 1.05, 95% confidence interval: 1.03, 1.07; P = 7.20 × 10−9; and BMI β = −0.065, 95% confidence interval: −0.087, −0.042; P = 1.30 × 10−8). rs705708 resides on 12q13.2, which harbors 9 other asthma- and BMI-associated variants (all P < 5 × 10−5 for asthma; all but one P < 5 × 10−5 for BMI). Follow-up analyses of rs705708 show that most of the BMI association occurred independently of asthma, with consistent magnitude between men and women and persons with and without asthma, irrespective of age at diagnosis; the asthma association was stronger for childhood versus adult asthma; and both associations remained after confounder adjustment. This suggests that 12q13.2 displays pleiotropy for asthma and BMI. Upon further characterization, 12q13.2 might provide a target for interventions that simultaneously prevent or treat asthma and obesity.