scholarly journals Frequency Response Evaluation of Guitar Bodies with Different Bracing Systems

Symmetry ◽  
2020 ◽  
Vol 12 (5) ◽  
pp. 795
Author(s):  
Mircea Mihălcică ◽  
Mariana D. Stanciu ◽  
Sorin Vlase
Keyword(s):  
Structural Features ◽  
Dynamic Force ◽  
Classical Guitar ◽  
Elastic Symmetry ◽  
Frequency Responses ◽  
Points Of View ◽  
Coupled Plates ◽  
Natural Composite ◽  
Theoretical Results ◽  
Symmetric Systems

Wood is a natural composite, having a porous structure, with a complex elastic symmetry specific to orthotropic solid, influenced by three mutually perpendicular planes of elastic symmetry. The classical guitar is obtained from different wooden species, each of them having their own elastic properties and, as a whole, forming a lignocellulosic composite structure. Generally, some constructive parts of the classical guitar body are based on symmetry, starting from the structural features of wooden plates, which are symmetrically cut, and some patterns of the stiffening bars. The other elements, such as the strings system, are not symmetric. This study aims to evaluate the frequency responses of the guitar body as a symmetrical mechanical system from constructive points of view. Because theoretical results (analytic and numeric) regarding the symmetrical systems cannot be applied to quasi-symmetric systems, the dynamic response was analyzed from experiments performed on four types of classical guitar body (without neck), different from each other by the pattern of stiffening bars placed inside of the top plate. The experiments were performed using a Brüel&Kjær mini-shaker to excite the structure, and the signal was captured with accelerometers. The symmetric behavior of coupled plates from the guitar body was noticed in the case of an applied dynamic force of 110 Hz and 440 Hz, but in the case of 146 Hz, 588 Hz, 720 Hz, quasi skew symmetrical modes were recorded.

Research of Product Design in Physically Processed Type Based on Bamboo Composite Characteristics

2011 ◽  
Vol 382 ◽  
pp. 30-33 ◽  
Author(s):  
Li Li Zhang ◽  
Dong Yang Lin
Keyword(s):  
Mechanical Properties ◽  
Composite Material ◽  
Product Design ◽  
Small Diameter ◽  
Structural Features ◽  
Chemical Components ◽  
Thin Wall ◽  
Geometric Configurations ◽  
Natural Composite ◽  
Line Type

Being a natural composite material, bamboo’s biological anatomy structure, chemical components and particularities in mechanical properties have some influences on the processing and manufacturing of bamboo materials. Based on micromechanical analysis and the combination of structural features of its hollow type curved surface and cleavability, this paper discusses about the feasibility about extension design of bamboo pole as a whole for modeling elements, any possible varieties by vertical and horizontal segmentation for diversified combinational designs like enclosure and assembly; as well as rationality about designing products models in association with line-type materials after cleavage and separation. In the meantime, it presents difficulties in processing and utilization owing to bamboo material’s characteristics in geometric configurations such as small diameter, hollowness, multisections, thin wall and taperingness, and also its only longitudinal fibers.

Analysis of typical locomotion of a symmetric hexapod robot

Robotica ◽  
2009 ◽  
Vol 28 (6) ◽  
pp. 893-907 ◽  
Author(s):  
Z.-Y. Wang ◽  
X.-L. Ding ◽  
A. Rovetta
Keyword(s):  
Fault Tolerance ◽  
Energy Management ◽  
Research Community ◽  
Robot Kinematics ◽  
Walking Ability ◽  
The Novel ◽  
Hexapod Robot ◽  
Points Of View ◽  
Hexapod Robots ◽  
Theoretical Results

SUMMARYIn recent years hexagonal hexapod robots gained the interest of international research community. The aim of this paper is twofold. First, after summarizing all known gaits of such robots, we introduce some improvements both for normal conditions and for fault tolerance. Then we show the advantages of hexagonal hexapod robots over rectangular ones by comparing different gaits from theoretical and experimental points of view. Stability, fault tolerance, turning ability, and terrain adaptability are analyzed. For reaching these aims we also introduce a robot kinematics that considers at the same time supporting and transferring legs. The trajectories of feet are described as well. Finally, single leg stride selection is studied for side wave and for kick-off gaits to optimize walking ability and energy management.The theoretical results presented herein have been validated with experiments conducted on a prototype of the Novel Robotics System for Planetary Exploration (Rovetta et al., “New Robot Concepts for Mars Soil Exploration: Mechanics and Functionality,” ASTRA 2004, Eighth ESA Workshop on Advanced Space Technologies for Robotics and Automatian, Nordwijk, The Netherlands Nov. 2–4, 2004) (NOROS), developed by Politecnico di Milano and Beijing University of Astronautics and Aeronautics, and the results are summarized in this paper.

scholarly journals An Investigation on Pervasive Technologies for IoT-based Thermal Monitoring

Sensors ◽  
2019 ◽  
Vol 19 (3) ◽  
pp. 663 ◽  
Author(s):  
Edoardo Giusto ◽  
Filippo Gandino ◽  
Michele Greco ◽  
Michelangelo Grosso ◽  
Bartolomeo Montrucchio ◽  
...  
Keyword(s):  
Radio Frequency Identification ◽  
Large Scale ◽  
Battery Life ◽  
Home Automation ◽  
Hvac System ◽  
Thermal Monitoring ◽  
System A ◽  
Frequency Identification ◽  
Points Of View ◽  
Theoretical Results

Indoor thermal monitoring is a crucial requirement for home automation, which fits inside the ever-growing Internet of Things (IoT) paradigm. The IoT ecosystem aims at connecting every device exploiting specific functions, deployed in a particular place, in order to give the chance to the users to monitor and/or control some aspects of their life, or to demand this task to a proper software. In the thermal monitoring context, IoT provides new opportunities for a dense and/or large-scale distribution of sensors, which have to gather data in order to effectively control the Heating, Ventilation and Air Conditioning (HVAC) system. Several wireless technologies can be exploited for this scope. However, they involve different benefits and drawbacks. In particular, this study is focused on Radio Frequency Identification (RFID) and Bluetooth®, which represent two well-known wireless technological standards used by commercial electronics but suitable also for pervasive IoT systems. These technologies are discussed and compared from several points of view, i.e., flexibility, reliability, battery life and cost of the system. A theoretical analysis highlights their benefits for the application context and evaluates their suitability to dense and large-scale monitoring systems. The theoretical results are supported by an experimental analysis based on the implementation and test of two different systems, one using RFID and the other using Bluetooth technology.

scholarly journals Исследование структурных особенностей дентина методами микротомографии и просвечивающей электронной микроскопии

2020 ◽  
Vol 90 (9) ◽  
pp. 1449
Author(s):  
Т.С. Аргунова ◽  
Ж.В. Гудкина ◽  
М.Ю. Гуткин ◽  
Д.В. Зайцев ◽  
А.Е. Калмыков ◽  
...  
Keyword(s):  
Structural Features ◽  
Human Teeth ◽  
Dentinal Tubules ◽  
X Ray ◽  
Transmission Electron ◽  
Secondary Cracks ◽  
Mode Ii Crack ◽  
The Matrix ◽  
Dentin Matrix ◽  
Natural Composite

Dentin of human teeth is a natural composite material with a layered hierarchical structure; it is formed by micro- and nanostructures whose complex relations obey the laws not yet fully understood. In order to understand the effect of the dentin structure on its mechanical properties, a study of dentin samples prepared from human molars and subjected to a uniaxial compression was made. Synchrotron X-ray microtomography and transmission electron microscopy were employed to investigate the elements of dentin matrix and the tubules which cross the matrix. Single structural features based on the interaction of the elements, as well as the properties of the dentinal tubules, which can stop crack propagation have been investigated. A model is proposed for calculating the conditions of stopping of a mode II crack by generation of secondary cracks caused by the stresses over the surfaces of the tubules.

scholarly journals Properties of Fourier Syntheses and New Syntheses

Crystals ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 538
Author(s):  
Maria Cristina Burla ◽  
Benedetta Carrozzini ◽  
Giovanni Luca Cascarano ◽  
Carmelo Giacovazzo ◽  
Giampiero Polidori
Keyword(s):  
Structural Model ◽  
Point Of View ◽  
Special Role ◽  
Fourier Synthesis ◽  
Practical Applications ◽  
Phase Extension ◽  
Points Of View ◽  
Theoretical Results

In this study, the properties of observed, difference, and hybrid syntheses (hybrid indicates a combination of observed and difference syntheses) are investigated from two points of view. The first has a statistical nature and aims to estimate the amplitudes of peaks corresponding to the model atoms, belonging or not belonging to the target structure; the amplitudes of peaks related to the target atoms, missed or shared with the model; and finally, the quality of the background. The latter point deals with the practical features of Fourier syntheses, the special role of weighted syntheses, and their usefulness in practical applications. It is shown how the properties of the various syntheses may vary according to the available structural model and, in particular, how weighted hybrid syntheses may act like an observed and difference or a full hybrid synthesis. The theoretical results obtained in this paper suggest new Fourier syntheses using novel Fourier coefficients: their main features are first discussed from a mathematical point of view. Extended experimental applications show that they meet the basic mission of the Fourier syntheses, enhancing peaks corresponding to the missed target atoms, depleting peaks corresponding to the model atoms not belonging to the target, and significantly reducing the background. A comparison with the results obtained via the most popular modern Fourier syntheses is made, suggesting a role for the new syntheses in modern procedures for phase extension and refinement. The most promising new Fourier synthesis has been implemented in the current version of SIR2014.

scholarly journals The Nature of the Chemical Bond in Linear Three-Body Systems: From I3–to Mixed Chalcogen/Halogen and Trichalcogen Moieties

2007 ◽  
Vol 2007 ◽  
pp. 1-46 ◽  
Author(s):  
M. Carla Aragoni ◽  
Massimiliano Arca ◽  
Francesco A. Devillanova ◽  
Alessandra Garau ◽  
Francesco Isaia ◽  
...  
Keyword(s):  
Chemical Bond ◽  
Energy Surface ◽  
Structural Data ◽  
Closed Shell ◽  
Structural Features ◽  
Donor Acceptor ◽  
Structural Database ◽  
Three Body ◽  
Van Der Waals Radii ◽  
Symmetric Systems

The 3 centre-4 electrons (3c-4e) and the donor/acceptor or charge-transfer models for the description of the chemical bond in linear three-body systems, such as I3–and related electron-rich (22 shell electrons) systems, are comparatively discussed on the grounds of structural data from a search of the Cambridge Structural Database (CSD). Both models account for a total bond order of 1 in these systems, and while the former fits better symmetric systems, the latter describes better strongly asymmetric situations. The 3c-4e MO scheme shows that any linear system formed by three aligned closed-shell species (24 shell electrons overall) has reason to exist provided that two electrons are removed from it to afford a 22 shell electrons three-body system: all combinations of three closed-shell halides and/or chalcogenides are considered here. A survey of the literature shows that most of these three-body systems exist. With some exceptions, their structural features vary continuously from the symmetric situation showing two equal bonds to very asymmetric situations in which one bond approaches to the value corresponding to a single bond and the second one to the sum of the van der Waals radii of the involved atoms. This indicates that the potential energy surface of these three-body systems is fairly flat, and that the chemical surrounding of the chalcogen/halogen atoms can play an important role in freezing different structural situations; this is well documented for the I3–anion. The existence of correlations between the two bond distances and more importantly the linearity observed for all these systems, independently on the degree of their asymmetry, support the state of hypervalency of the central atom.

scholarly journals Experimental demonstration of coherence flow in PT- and anti-PT-symmetric systems

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Yu-Liang Fang ◽  
Jun-Long Zhao ◽  
Yu Zhang ◽  
Dong-Xu Chen ◽  
Qi-Cheng Wu ◽  
...  
Keyword(s):  
Experimental Data ◽  
Standard Deviation ◽  
Future Study ◽  
Symmetric System ◽  
Experimental Demonstration ◽  
Periodic Oscillations ◽  
Single Qubit ◽  
Quantum Properties ◽  
Theoretical Results ◽  
Symmetric Systems

AbstractNon-Hermitian parity-time ($${{{{{{{\mathcal{P}}}}}}}}{{{{{{{\mathcal{T}}}}}}}}$$ P T ) and anti-parity-time ($${{{{{{{\mathcal{APT}}}}}}}}$$ APT )-symmetric systems exhibit novel quantum properties and have attracted increasing interest. Although many counterintuitive phenomena in $${{{{{{{\mathcal{P}}}}}}}}{{{{{{{\mathcal{T}}}}}}}}$$ P T - and $${{{{{{{\mathcal{APT}}}}}}}}$$ APT -symmetric systems were previously studied, coherence flow has been rarely investigated. Here, we experimentally demonstrate single-qubit coherence flow in $${{{{{{{\mathcal{P}}}}}}}}{{{{{{{\mathcal{T}}}}}}}}$$ P T - and $${{{{{{{\mathcal{APT}}}}}}}}$$ APT -symmetric systems using an optical setup. In the symmetry unbroken regime, we observe different periodic oscillations of coherence. Particularly, we observe two complete coherence backflows in one period in the $${{{{{{{\mathcal{P}}}}}}}}{{{{{{{\mathcal{T}}}}}}}}$$ P T -symmetric system, while only one backflow in the $${{{{{{{\mathcal{APT}}}}}}}}$$ APT -symmetric system. Moreover, in the symmetry broken regime, we observe the phenomenon of stable value of coherence flow. We derive the analytic proofs of these phenomena and show that most experimental data agree with theoretical results within one standard deviation. This work opens avenues for future study on the dynamics of coherence in $${{{{{{{\mathcal{P}}}}}}}}{{{{{{{\mathcal{T}}}}}}}}$$ P T - and $${{{{{{{\mathcal{APT}}}}}}}}$$ APT -symmetric systems.

Synthesis and structure of stable 1,2-diaryldisilyne

2010 ◽  
Vol 82 (3) ◽  
pp. 603-612 ◽  
Author(s):  
Takahiro Sasamori ◽  
Joon Soo Han ◽  
Koji Hironaka ◽  
Nozomi Takagi ◽  
Shigeru Nagase ◽  
...  
Keyword(s):  
Triple Bond ◽  
Theoretical Calculations ◽  
Structural Features ◽  
Stable Compound ◽  
Theoretical Results ◽  
Bond Character ◽  
Methyl Phenyl

A novel 1,2-diaryldisilyne, BbtSi≡SiBbt (Bbt = 2,6-bis[bis(trimethylsilyl)methyl]-4-[tris(trimethylsilyl)methyl]phenyl), was synthesized as a stable compound by reduction of the corresponding 1,2-dibromodisilene, Bbt(Br)Si=Si(Br)Bbt. The spectral and structural features of this first stable 1,2-diaryldisilyne are revealed, and the Si≡Si triple-bond character is evaluated with the aid of detailed theoretical calculations. The triple-bond characters of BbtSi≡SiBbt and BbtGe≡GeBbt are compared based on experimental and theoretical results.

scholarly journals THE CONTENT OF TYPES OF COMMUNICATION IN THE PEDAGOGICAL PROCESS

2021 ◽  
pp. 180-191
Author(s):  
Bakhytzhan Begenbekovna Ospanova ◽  
Gulmira Mukhamedzhanovna Tulekova
Keyword(s):  
Business Communication ◽  
Structural Features ◽  
Communication Process ◽  
Depth Of Penetration ◽  
Professional Characteristics ◽  
Points Of View ◽  
Definition Of ◽  
Collaborative Activities ◽  
Pedagogical Goals ◽  
Spatial And Temporal Characteristics

The article is devoted to the description of various approaches to the interpretation of communication as a complex, multifunctional and multicomponent process. Types of communication are distinguished depending on a number of grounds, signs, criteria. The article presents the scientific points of view of domestic and foreign scientists on the understanding and definition of the term communication, shows the types of communication, identified with regard to content functional and structural features, taking into account the spatial and temporal characteristics of the communication process, as well as other grounds: by sphere of activity, by degree of mediation, by orientation, by depth of penetration, by types of communication of subjects, by professional characteristics. In addition, the criteria for classifying types of communication are also the nature, goals, forms of expression and direction of communication, etc. In the light of the global challenges of our time, the problems of remote business communication, including business communication in mentoring activities, are being updated. Within the framework of mentoring, business communication is carried out taking into account certain standards based on the constructivist paradigm, which provides for the implementation of external and internal pedagogical goals. In the distance format, business communication is aimed both at solving the problems of individual educational trajectory of a particular student («teacher ↔ student»), and at organizing joint collaborative activities of students («teacher ↔ students», «student ↔ students», «students ↔ students»).

Sign in / Sign up

Export Citation Format

Share Document