asymmetrical shape
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2021 ◽  
pp. 364-374

The south-eastern part of the Bükk Mountains and the eastern side of its foothill, the Bükkalja are among the less explored regions of Hungary. Based on our examinations on the field, we found that the asymmetrical valley sections, the tipped escarpments and the formation of the Kisgyőr Basin cannot be explained by the differences in the rock quality. The asymmetrical shape of these landforms and the stream captures identified in the research area indicate significant structural geological changes. In our work, we proved the asymmetry in the topography by performing swath profile analysis, and we also examined the elevation data of the areas covered by the welded ignimbrites of the Tar Dacite Tuff Formation. The results confirmed our field observations. We found that, contrary to the results of previous research, the geological structural processes played a fundamental role in the formation of the Kisgyőr Basin and its surroundings.


2021 ◽  
Author(s):  
Bahram Raeisi

Tilting ducted fans attached to the wing tips of vertical take-off and landing unmanned aerial vehicles (VTOL UAVs) define new applications for these types of vehicles. This new configuration gives VTOL UAVs the ability to hover like helicopters and fly forward like airplanes. These abilities provide VTOL UAVs with possibility of using any arbitrary location for take-off and landing combined with enhanced range and speed. The thrust vectoring is another advantage of this new configuration, which can be used in most of the necessary maneuvers. The flow behaviour around tilting ducted fans needs to be studied as it has significant effects on the performance of the VTOL UAVs. The first objective of this research is to investigate the use of asymmetrical shape for the external body of ducted fans. This geometry can generate additional lift in cruise mode, which can lead to more applications for the VTOL UAVs by saving more energy. Both CFD and experimental methods showed noticeable improvement in the lift velocity (Vind) of the inlet flow to the rotor plane. This is required for computing aerodynamic coefficients necessary for stability and control analysis of the proposed VTOL UAV. “Actuator Disk Model” combined with the assumption of “Constant Delivered Power” to the propeller were used successfully to calculate Vind for the CFD simulations. The third objective is using CFD coefficient by using an asymmetrical ducted fan. The second objective is to predict the induced simulation for predicting aerodynamic forces and pitching moments of the tilting ducted fans in the transition conditions for different tilting rates. The effects of the stall and flow separation on the aerodynamic coefficients were discussed and compared for both ducted fans. The fourth objective is using the aerodynamic coefficients of the tilting ducted fans to predict and compare the level flight conditions of the proposed VTOL UAV during transition between cruise mode and hover. Results of this research demonstrate satisfactory agreement between CFD simulations and wind tunnel tests for all of these objectives, which could predict the aerodynamic behaviour of the proposed VTOL UAV during transition between cruise mode and hover.


2021 ◽  
Author(s):  
Bahram Raeisi

Tilting ducted fans attached to the wing tips of vertical take-off and landing unmanned aerial vehicles (VTOL UAVs) define new applications for these types of vehicles. This new configuration gives VTOL UAVs the ability to hover like helicopters and fly forward like airplanes. These abilities provide VTOL UAVs with possibility of using any arbitrary location for take-off and landing combined with enhanced range and speed. The thrust vectoring is another advantage of this new configuration, which can be used in most of the necessary maneuvers. The flow behaviour around tilting ducted fans needs to be studied as it has significant effects on the performance of the VTOL UAVs. The first objective of this research is to investigate the use of asymmetrical shape for the external body of ducted fans. This geometry can generate additional lift in cruise mode, which can lead to more applications for the VTOL UAVs by saving more energy. Both CFD and experimental methods showed noticeable improvement in the lift velocity (Vind) of the inlet flow to the rotor plane. This is required for computing aerodynamic coefficients necessary for stability and control analysis of the proposed VTOL UAV. “Actuator Disk Model” combined with the assumption of “Constant Delivered Power” to the propeller were used successfully to calculate Vind for the CFD simulations. The third objective is using CFD coefficient by using an asymmetrical ducted fan. The second objective is to predict the induced simulation for predicting aerodynamic forces and pitching moments of the tilting ducted fans in the transition conditions for different tilting rates. The effects of the stall and flow separation on the aerodynamic coefficients were discussed and compared for both ducted fans. The fourth objective is using the aerodynamic coefficients of the tilting ducted fans to predict and compare the level flight conditions of the proposed VTOL UAV during transition between cruise mode and hover. Results of this research demonstrate satisfactory agreement between CFD simulations and wind tunnel tests for all of these objectives, which could predict the aerodynamic behaviour of the proposed VTOL UAV during transition between cruise mode and hover.


This paper discusses the analysis results of determining the bandwidth and working frequency of a bi-circular antenna design. The analysis was carried out using three approaches, namely the FDTD simulation method, the measurement method using a network analyzer on the fabrication results of the antenna design, and the method of applying the bi-polygonal antenna model to the bi-circular antenna design. The novelty in this research is the application of the bi-polygonal antenna model and the comparison of the results of determining the bandwidth and working frequency of a bi-circular antenna with these three methods. Based on the results of the analysis using these three methods, it was found that different bandwidth values and the same antenna working frequency value were 2.45 GHz. The modeling results give a narrow and symmetrical form of return loss vs. frequency curve, the simulation results give a wide and slightly symmetrical form of return loss vs. frequency curve, and the measurement results give a wide and asymmetrical shape of return loss vs. frequency curve.


2021 ◽  
pp. 32-40
Author(s):  
Liliya Chertenko

The production of such footwear as riding boots requires additional equipment like a special mold for the formation of bootlegs, which are made using intermediate frame parts to ensure rigidity and preserving shape. The special mold of riding boots is a stylized shape of the leg from its foot to knee. The lower part corresponding to the shoe last is designed based on the parameters of the average foot, taking into account the requirements of biomechanics, physiology, and aesthetic features of the shoe style. The upper part repeats the parameters of the shin and has a specifi c asymmetrical shape, which ensures a stylish and perfect form of the riding boot. To obtain the initial data for designing the mold, there were performed anthropometric measurements of the shins of young women whose feet sizes correspond to the average ones in the selected sample. Designing of the lower part of the mold was carried out on the basis of the average parameters of the foot in Crispin LastMaker software complex using the method of reverse engineering. Designing of the general shape was performed in the PowerShape software environment by means of the features of surface, solid, and hybrid modeling. This type of boots must be made with several width-girth parameters, and the possibility to make boots with diff erent designs must be provided. Therefore, in order to e ff ectively use the molding means (a boot-tree), in the work, there was proposed the transforming mold, which allows making boots of diff erent widths and with diff erent shapes of the toe part due to its struc ture consisting of four parts changing the relative position and individual elements due to which it is possible to achieve multipurpose usage. Objective. Development of an improved shape, design, and method of designing a boot-tree molding means based on the foot 3d scan and shin measurements using the features of modern CAD software.Topicality of the work is based on the need to equip footwear production with the advanced lasts and molding means taking into account the requirements of ergonomics and fashionable design. Novelty. The proposed structure of the boot-tree developed on the basis of foot measurements is designed using a combination of reverse and direct modeling of the shape, which allows achieving the ideal and unique 3D shape combining ergonomic features and beautiful design. Such design method allows using the available digital equipment to obtain the initial data.


2020 ◽  
Vol 31 ◽  
pp. 478-491
Author(s):  
H. Rashid ◽  
G. Hussain ◽  
K. Rehman ◽  
S. Khan ◽  
Mohammed Alkahtani ◽  
...  

2020 ◽  
pp. 1-40
Author(s):  
Steven Foley ◽  
Maziar Toosarvandani

In many languages with clitic or other weak pronouns, a Person-Case Constraint (Perlmutter 1971, Bonet 1991) prohibits certain combinations of these pronouns on the basis of their person features. This article explores the crosslinguistic variation in such constraints, starting with several closely related Zapotec varieties. These restrict combinations of clitics not just on the basis of person, but also on the basis of a finely articulated, largely animacy-based gender system. Operating within a larger combinatorial space, these constraints offer a new perspective on the typology of Phi-Case Constraints (ΦCCs) more generally. This typology has an overall asymmetrical shape correlating with the underlying syntactic position of pronominal arguments. We develop a principled theory of this typology that incorporates three hypotheses: (a) ΦCCs arise from how a functional head Agrees with clitic pronouns, subject to intervention-based locality (Anagnostopoulou 2003, Béjar and Rezac 2003, 2009); (b) the variation in these constraints arises from variation in the relativization of probes (Anagnostopoulou 2005, Nevins 2007, 2011); and (c) clitic and other weak pronouns have no inherent need to be licensed via Agree with a functional head. Under this account, the crosslinguistic typology of ΦCCs has the potential to shed light on the grammatical representation of person and gender.


Sensors ◽  
2020 ◽  
Vol 20 (3) ◽  
pp. 829 ◽  
Author(s):  
Steponas Ašmontas ◽  
Maksimas Anbinderis ◽  
Aurimas Čerškus ◽  
Jonas Gradauskas ◽  
Algirdas Sužiedėlis ◽  
...  

We propose a new design microwave radiation sensor based on a selectively doped semiconductor structure of asymmetrical shape (so-called bow-tie diode). The novelty of the design comes down to the gating of the active layer of the diode above different regions of the two-dimensional electron channel. The gate influences the sensing properties of the bow-tie diode depending on the nature of voltage detected across the ungated one as well as on the location of the gate in regard to the diode contacts. When the gate is located by the wide contact, the voltage sensitivity increases ten times as compared to the case of the ungated diode, and the detected voltage holds the same polarity of the thermoelectric electromotive force of hot electrons in an asymmetrically shaped n-n+ junction. Another remarkable effect of the gate placed by the wide contact is weak dependence of the detected voltage on frequency which makes such a microwave diode to be a proper candidate for the detection of electromagnetic radiation in the microwave and sub-terahertz frequency range. When the gate is situated beside the narrow contact, the two orders of sensitivity magnitude increase are valid in the microwaves but the voltage sensitivity is strongly frequency-dependent for higher frequencies.


Paleo-aktueel ◽  
2019 ◽  
pp. 45-53
Author(s):  
Annet Nieuwhof ◽  
Reinder Reinders

Shovel, spade or side rudder? A special find from Ezinge. In 1933, excavations in the terp of Ezinge (province of Groningen) uncovered an object made out of oak in a house dating from the beginning of the 5th century BC. The object was recorded as a wooden shovel. Its asymmetrical shape, in combination with its lack of handle and its perforated shaft, however, suggest that it may not be a shovel (or a spade), although the possibility cannot be ruled out altogether. The shape of the object seems suitable for use as a side rudder, used to steer a long, dugout canoe powered by multiple paddlers. The earliest side rudders reported in the literature from northwestern Europe are from the late Roman period in southern Scandinavia. If the object could be proven to be a side rudder, it would be a rare find. It would also be one of a very small number of finds that can be associated with boats in the maritime landscape where Ezinge was situated. We recommend experimental research to better understand the use of dugout canoes and side rudders, and to reassess similar objects that have been recorded as shovels or spades.


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