Designing and producing a bird-inspired unmanned sailplane

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Göksel Keskin ◽  
Seyhun Durmus ◽  
Muharrem Karakaya ◽  
Melih Cemal Kushan
Keyword(s):  
Fuel Efficiency ◽  
Traffic Monitoring ◽  
Dynamics Simulation ◽  
Design Parameters ◽  
Flight Performance ◽  
Bird Flight ◽  
Flight Duration ◽  
Content Type ◽  
Battery Capacity ◽  
Almost All

Purpose Increasing endurance was a very appropriate subject for the biomimetic approach. The study aims to design and manufacture a long-lasting mini unmanned aerial vehicle (UAV) using active gliding and soaring. Design/methodology/approach The endurance of mini UAVs is limited by battery or fuel capacity, and it is not always possible to increase these energy sources due to the fuselage size. Long endurance aircraft are required in various areas such as silent environment and traffic monitoring or search and rescue. Literature research on bird flight performance conducted to determine design parameters. These parameters are used in the theoretical design of the UAV for optimization. Computational fluid dynamics simulation and flight tests of the UAV performed to figure out the success of the design. Findings For a mini UAV to be produced in this class, it has been observed that it is more accurate to examine birds instead of gliders due to the size similarity. The UAV design reaches a 27.5 L/D (Glide ratio) ratio in the theoretical approach. However, flight results approved max L/D ratio is around 25 at the sea level. This flight performance is enough to outperform in glide ratio of Wandering albatrosses. Practical implications Sailplanes are known as sport aircraft. However, recent projects focus on glider designs due to fuel efficiency and silent tracking. Stemme S-14 that carries a high-resolution camera is one of the examples of these projects. The unmanned glider design can lead to these implications in the UAVs at least during the stand-by period in the air. Thanks to low weight, UAVs do not require strong thermals, which allows flying almost all over the world. Originality/value Researchers generally focus on increasing the battery capacity or the performance of the UAV. However, this study’s concentration is to increase the flight duration of the UAV by using geographical currents. For this purpose, taking advantage of bird morphology is quite a new topic. Also, glider type designs are rarely found in the field.

scholarly journals Aerodynamic performance of flying discs

2018 ◽  
Vol 90 (2) ◽  
pp. 390-397
Author(s):  
Noorfazreena Kamaruddin ◽  
Jonathan Potts ◽  
William Crowther
Keyword(s):  
Design Methodology ◽  
Aerodynamic Characteristics ◽  
Design Parameters ◽  
Flight Performance ◽  
Content Type ◽  
Six Degree Of Freedom ◽  
Design Factors ◽  
Drag Ratio ◽  
Lift To Drag Ratio ◽  
Practical Implications

Purpose The purpose of this paper is to examine geometrical design influence of various types of flying discs on their flight performance from the aerodynamics perspective. Design/methodology/approach The lift, drag and moment coefficients of the discs were measured experimentally using a wind tunnel. Three types of golf discs and four sets of simpler parametric discs were studied to analyze and isolate the effect of design factors on these aerodynamic characteristics. Full six degree-of-freedom simulations of the discs were performed to visualize their flight trajectories and attitudes. These simulations, combined with the experimental data, provide details on the well-known “S-shaped” ground-path traced by a flying disc. Findings This paper reveals two key parameters to evaluate the flight performance of a disc: its coefficient of lift-to-drag ratio (CL/CD) and, more importantly, its coefficient of pitching moment (CM). The latter influences the tendency of the disc to yaw from its intended path, and the former influences its throwing distance. Practical implications The work suggests that to optimize the flight performance of a disc, the magnitudes and gradient of its CM should be minimized and its trim-point shifted from origin, while its CL/CD should be maximized with a flatter peak. Originality/value In this paper, the design parameters and the aerodynamic characteristics of various types of flying discs are analysed, compared and discussed in depth. Recommendations of design improvements to enhance the performance of any flying disc are offered as well.

Lumbosacral intersegmental epispinal axons and ectopic ventral nerve rootlets

1987 ◽  
Vol 67 (2) ◽  
pp. 269-277 ◽  
Author(s):  
Wesley W. Parke ◽  
Ryo Watanabe
Keyword(s):  
Nerve Root ◽  
Sensory Nerve ◽  
Conus Medullaris ◽  
Spinal Nerve ◽  
Nerve Fibers ◽  
Ventral Horn ◽  
Spinal Nerve Roots ◽  
Nerve Roots ◽  
Content Type ◽  
Almost All

✓ An epispinal system of motor axons virtually covers the ventral and lateral funiculi of the human conus medullaris between the L-2 and S-2 levels. These nerve fibers apparently arise from motor cells of the ventral horn nuclei and join spinal nerve roots caudal to their level of origin. In all observed spinal cords, many of these axons converged at the cord surface and formed an irregular group of ectopic rootlets that could be visually traced to join conventional spinal nerve roots at one to several segments inferior to their original segmental level; occasional rootlets joined a dorsal nerve root. As almost all previous reports of nerve root interconnections involved only the dorsal roots and have been cited to explain a lack of an absolute segmental sensory nerve distribution, it is believed that these intersegmental motor fibers may similarly explain a more diffuse efferent distribution than has previously been suspected.

Applicability of the DUNDRUM-1 in a forensic Belgium setting

2019 ◽  
Vol 21 (1) ◽  
pp. 85-94 ◽  
Author(s):  
Petra Habets ◽  
Inge Jeandarme ◽  
Harry G. Kennedy
Keyword(s):  
Repeated Measurements ◽  
Security Level ◽  
Rater Reliability ◽  
Content Type ◽  
Forensic Patients ◽  
Item Level ◽  
Dundrum Toolkit ◽  
Male Patients ◽  
Receive Treatment ◽  
Almost All

Purpose Criteria to determine in which level of security forensic patients should receive treatment are currently non-existent in Belgium. Research regarding the assessment of security level is minimal and few instruments are available. The DUNDRUM toolkit is a structured clinical judgement instrument that can be used to provide support when determining security level. The purpose of this paper is to investigate the applicability and validity of the DUNDRUM-1 in Flanders. Design/methodology/approach The DUNDRUM-1 was scored for 50 male patients admitted at the forensic units in the public psychiatric hospital Rekem. Some files were rated by three researchers who were blind to participants’ security status, resulting in 33 double measurements. Findings Almost all files (96 per cent) contained enough information to score the DUNDRUM-1. Average DUNDRUM-1 final judgement scores were concordant with a medium security profile. No difference was found between the current security levels and the DUNDRUM-1 final judgement scores. Inter-rater reliability was excellent for the DUNDRUM-1 final judgement scores. On item level, all items had excellent to good inter-rater reliability with the exception of one item institutional behaviour which had an average inter-rater reliability. Practical implications The DUNDRUM-1 can be a useful tool in Flemish forensic settings. It has good psychometric properties. More research is needed to investigate the relationship between DUNDRUM-1 scores and security level decisions by the courts. Originality/value This is the first study that investigated the applicability of the DUNDRUM-1 in a Belgian setting, also a relative large number of repeated measurements were available to investigate the inter-rater reliability of the DUNDRUM-1.

Workspace, dexterity and dimensional optimization of microhexapod

2015 ◽  
Vol 35 (4) ◽  
pp. 341-347 ◽  
Author(s):  
E. Rouhani ◽  
M. J. Nategh
Keyword(s):  
Degrees Of Freedom ◽  
Optimization Problem ◽  
Screw Theory ◽  
Design Parameters ◽  
Dimensional Synthesis ◽  
Content Type ◽  
Workspace Analysis ◽  
The Difference ◽  
Flexure Joints ◽  
6 Degrees Of Freedom

Purpose – The purpose of this paper is to study the workspace and dexterity of a microhexapod which is a 6-degrees of freedom (DOF) parallel compliant manipulator, and also to investigate its dimensional synthesis to maximize the workspace and the global dexterity index at the same time. Microassembly is so essential in the current industry for manufacturing complicated structures. Most of the micromanipulators suffer from their restricted workspace because of using flexure joints compared to the conventional ones. In addition, the controllability of micromanipulators inside the whole workspace is very vital. Thus, it is very important to select the design parameters in a way that not only maximize the workspace but also its global dexterity index. Design/methodology/approach – Microassembly is so essential in the current industry for manufacturing complicated structures. Most of the micromanipulators suffer from their restricted workspace because of using flexure joints compared to the conventional ones. In addition, the controllability of micromanipulators inside the whole workspace is very vital. Thus, it is very important to select the design parameters in a way that not only maximize the workspace but also its global dexterity index. Findings – It has been shown that the proposed procedure for the workspace calculation can considerably speed the required calculations. The optimization results show that a converged-diverged configuration of pods and an increase in the difference between the moving and the stationary platforms’ radii cause the global dexterity index to increase and the workspace to decrease. Originality/value – The proposed algorithm for the workspace analysis is very important, especially when it is an objective function of an optimization problem based on the search method. In addition, using screw theory can simply construct the homogeneous Jacobian matrix. The proposed methodology can be used for any other micromanipulator.

scholarly journals A Distinctive and Host-Restricted Gut Microbiota in Populations of a Cactophilic Drosophila Species

2017 ◽  
Vol 83 (23) ◽  
Author(s):  
Vincent G. Martinson ◽  
Javier Carpinteyro-Ponce ◽  
Nancy A. Moran ◽  
Therese A. Markow
Keyword(s):  
Sonoran Desert ◽  
Natural Habitat ◽  
Natural Food ◽  
Content Type ◽  
Columnar Cacti ◽  
Social Bees ◽  
Insect Gut ◽  
Almost All ◽  
Natural Settings ◽  
Bacterial Groups

ABSTRACT Almost all animals possess gut microbial communities, but the nature of these communities varies immensely. For example, in social bees and mammals, the composition is relatively constant within species and is dominated by specialist bacteria that do not live elsewhere; in laboratory studies and field surveys of Drosophila melanogaster, however, gut communities consist of bacteria that are ingested with food and that vary widely among individuals and localities. We addressed whether an ecological specialist in its natural habitat has a microbiota dominated by gut specialists or by environmental bacteria. Drosophila nigrospiracula is a species that is endemic to the Sonoran Desert and is restricted to decaying tissues of two giant columnar cacti, Pachycereus pringlei (cardón cactus) and Carnegiea gigantea (saguaro cactus). We found that the D. nigrospiracula microbiota differs strikingly from that of the cactus tissue on which the flies feed. The most abundant bacteria in the flies are rare or completely absent in the cactus tissue and are consistently abundant in flies from different cacti and localities. Several of these fly-associated bacterial groups, such as the bacterial order Orbales and the genera Serpens and Dysgonomonas, have been identified in prior surveys of insects from the orders Hymenoptera, Coleoptera, Lepidoptera, and Diptera, including several Drosophila species. Although the functions of these bacterial groups are mostly unexplored, Orbales species studied in bees are known to break down plant polysaccharides and use the resulting sugars. Thus, these bacterial groups appear to be specialized to the insect gut environment, where they may colonize through direct host-to-host transmission in natural settings. IMPORTANCE Flies in the genus Drosophila have become laboratory models for microbiota research, yet the bacteria commonly used in these experiments are rarely found in wild-caught flies and instead represent bacteria also present in the food. This study shows that an ecologically specialized Drosophila species possesses a distinctive microbiome, composed of bacterial types absent from the flies' natural food but widespread in other wild-caught insects. This study highlights the importance of fieldwork-informed microbiota research.

Gated communities in Ankara: are they a tool of social segregation?

2017 ◽  
Vol 10 (5) ◽  
pp. 687-702
Author(s):  
Leyla Alkan-Gökler
Keyword(s):  
Socioeconomic Status ◽  
Design Methodology ◽  
Gated Communities ◽  
Content Type ◽  
Positive View ◽  
Social Segregation ◽  
Show Evidence ◽  
Local Residents ◽  
Almost All ◽  
The Impact

Purpose Gated communities, surrounded by walls or fences, have emerged as a new trend in almost all cities in Turkey, and are homogenous in terms of the socioeconomic status of their occupants. Within these communities, several facilities and services are provided that are available only to the residents, with restrictions on access from the outside, and this has led to criticisms of social segregation. This study aims to analyze the impact of these communities on social segregation in Ankara, through two different surveys aimed at investigating the attitudes of the residents of local neighborhoods and gated communities toward each other. Design/methodology/approach This paper analyzes how the process of gating has affected social segregation in Ankara through two separate surveys: with the residents of gated communities and with the residents of local neighborhoods around these gated communities. Findings The study revealed that the residents of gated communities tended to have a positive view of the residents of local neighborhoods. In contrast, the responses of the local residents show evidence of feelings of social segregation, based on the presence of the high walls, fences and guards that are in place to keep them out of the community. Originality/value This study shows that, although segregation from the rest of the society is not the main reason for gating, the emergence of gated communities in Ankara leads inevitably to a socially and economically segregated city in which local residents feel excluded from these gated areas.

Analytic Optimization of Cost Effective Thermoelectric Generation on Top of Rankine Cycle

2013 ◽  
Author(s):  
Kazuaki Yazawa ◽  
Yee Rui Koh ◽  
Ali Shakouri
Keyword(s):  
Steam Turbine ◽  
Fuel Efficiency ◽  
Cost Effective ◽  
Rankine Cycle ◽  
Energy Conversion Efficiency ◽  
Design Parameters ◽  
Steam Temperature ◽  
Combined System ◽  
Fuel Consumption Rate ◽  
The Impact

Thermoelectric (TE) generators have a potential advantage of the wide applicable temperature range by a proper selection of materials. In contrast, a steam turbine (ST) as a Rankine cycle thermodynamic generator is limited up to more or less 630 °C for the heat source. Unlike typical waste energy recovery systems, we propose a combined system placing a TE generator on top of a ST Rankine cycle generator. This system produces an additional power from the same energy source comparing to a stand-alone steam turbine system. Fuel efficiency is essential both for the economic efficiency and the ecological friendliness, especially for the global warming concern on the carbon dioxide (CO2) emission. We report our study of the overall performance of the combined system with primarily focusing on the design parameters of thermoelectric generators. The steam temperature connecting two individual generators gives a trade-off in the system design. Too much lower the temperature reduces the ST performance and too much higher the temperature reduces the temperature difference across the TE generator hence reduces the TE performance. Based on the analytic modeling, the optimum steam temperature to be designed is found near at the maximum power design of TE generator. This optimum point changes depending on the hours-of-operation. It is because the energy conversion efficiency directly connects to the fuel consumption rate. As the result, physical upper-limit temperature of steam for ST appeared to provide the best fuel economy. We also investigated the impact of improving the figure-of-merit (ZT) of TE materials. As like generic TE engines, reduction of thermal conductivity is the most influential parameter for improvement. We also discuss the cost-performance. The combined system provides the payback per power output at the initial and also provides the significantly better energy economy [$/KWh].

Investigation of sustainability of lubricated journal bearing under relevant design parameters

2018 ◽  
Vol 70 (4) ◽  
pp. 789-804 ◽  
Author(s):  
M.M. Shahin ◽  
Mohammad Asaduzzaman Chowdhury ◽  
Md. Arefin Kowser ◽  
Uttam Kumar Debnath ◽  
M.H. Monir
Keyword(s):  
Aspect Ratio ◽  
Elastic Strain ◽  
Journal Bearing ◽  
Design Parameters ◽  
Content Type ◽  
Computational Fluid Dynamics Cfd ◽  
Stress Formation ◽  
Bearing Design ◽  
The Stability ◽  
Bearing Friction

Purpose The purposes of the present study are to ensure higher sustainability of journal bearings under different applied loads and to observe bearing performances such as elastic strain, total deformation and stress formation. Design/methodology/approach A journal bearing test rig was used to determine the effect of the applied load on the bearing friction, film thickness, lubricant film pressure, etc. A steady-state analysis was performed to obtain the bearing performance. Findings An efficient aspect ratio (L/D) range was obtained to increase the durability or the stability of the bearing while the bearing is in the working condition by using SAE 5W-30 oil. The results from the study were compared with previous studies in which different types of oil and water, such as Newtonian fluid (NF), magnetorheological fluid (MRF) and nonmagnetorheological fluid (NMRF), were used as the lubricant. To ensure a preferable aspect ratio range (0.25-0.50), a computational fluid dynamics (CFD) analysis was conducted by ANSYS; the results show a lower elastic strain and deformation within the preferable aspect ratio (0.25-0.50) rather than a higher aspect ratio using the SAE 5W-30 oil. Originality/value It is expected that the findings of this study will contribute to the improvement of the bearing design and the bearing lubricating system.

scholarly journals Phylogenetic Grouping and Virulence Potential of Extended-Spectrum-β-Lactamase-Producing Escherichia coli Strains in Cattle

2012 ◽  
Vol 78 (13) ◽  
pp. 4677-4682 ◽  
Author(s):  
Charlotte Valat ◽  
Frédéric Auvray ◽  
Karine Forest ◽  
Véronique Métayer ◽  
Emilie Gay ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Virulence Determinants ◽  
Phylogenetic Groups ◽  
Content Type ◽  
E Coli ◽  
Extended Spectrum ◽  
Specific Distribution ◽  
Extended Spectrum Beta Lactamases ◽  
Phylogenetic Grouping ◽  
Almost All

ABSTRACTIn line with recent reports of extended-spectrum beta-lactamases (ESBLs) inEscherichia coliisolates of highly virulent serotypes, such as O104:H4, we investigated the distribution of phylogroups (A, B1, B2, D) and virulence factor (VF)-encoding genes in 204 ESBL-producingE. coliisolates from diarrheic cattle. ESBL genes, VFs, and phylogroups were identified by PCR and a commercial DNA array (Alere, France). ESBL genes belonged mostly to the CTX-M-1 (65.7%) and CTX-M-9 (27.0%) groups, whereas those of the CTX-M-2 and TEM groups were much less represented (3.9% and 3.4%, respectively). One ESBL isolate wasstx1andeaepositive and belonged to a major enterohemorrhagicE. coli(EHEC) serotype (O111:H8). Two other isolates wereeaepositive butstxnegative; one of these had serotype O26:H11. ESBL isolates belonged mainly to phylogroup A (55.4%) and, to lesser extents, to phylogroups D (25.5%) and B1 (15.6%), whereas B2 strains were quasi-absent (1/204). The number of VFs was significantly higher in phylogroup B1 than in phylogroups A (P= 0.04) and D (P= 0.02). Almost all of the VFs detected were found in CTX-M-1 isolates, whereas only 64.3% and 33.3% of them were found in CTX-M-9 and CTX-M-2 isolates, respectively. These results indicated that the widespread dissemination of theblaCTX-Mgenes within theE. colipopulation from cattle still spared the subpopulation of EHEC/Shiga-toxigenicE. coli(STEC) isolates. In contrast to other reports on non-ESBL-producing isolates from domestic animals, B1 was not the main phylogroup identified. However, B1 was found to be the most virulent phylogroup, suggesting host-specific distribution of virulence determinants among phylogenetic groups.

Demonstration of the relationship between MSD and online learning during the COVID-19 pandemic

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Kochu Therisa Karingada ◽  
Michael Sony
Keyword(s):  
Online Learning ◽  
Undergraduate Students ◽  
Online Survey ◽  
Cross Sectional Study ◽  
The Body ◽  
Body Parts ◽  
Cross Sectional ◽  
Content Type ◽  
The Right ◽  
Almost All

PurposeThe COVID-19 pandemic lockdown has caught many educational institutions by surprise and warranted an abrupt migration from offline to online learning. This has resulted in an education change, without any time for due consideration, as regards its impact on musculoskeletal disorders (MSD) on students. The purpose of this study is to investigate MSD related to online learning during the COVID-19 pandemic lockdown.Design/methodology/approachA cross-sectional study was conducted on undergraduate students in India. In total, 261 students participated in this online survey.FindingsThe study finds that around 80% of students have reported some symptom in the head, neck and eyes since they started online learning. In total, 58% have reported MSD symptom in the right shoulder and 56% in the right hand fingers. Besides, more than 40 % of students experienced some MSD symptoms, in almost all the body parts studied, due to online learning. Correlation analysis is conducted between time spent on online learning per day and MSD symptoms.Originality/valueThis is the first study conducted on MSD and online learning during COVID-19 pandemic.

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