scholarly journals Damping control in viscoelastic beam dynamics

2020 ◽  
Vol 26 (19-20) ◽  
pp. 1753-1764 ◽  
Author(s):  
Elena Pierro
Keyword(s):  
Deep Understanding ◽  
Beam Dynamics ◽  
Viscoelastic Beam ◽  
Practical Applications ◽  
Research Fields ◽  
Damping Control ◽  
Beam Geometry ◽  
Viscoelastic Modulus ◽  
Transversal Vibrations

Viscoelasticity plays a key role in many practical applications and in different research fields, such as in seals, sliding-rolling contacts, and crack propagation. In all these contexts, a proper knowledge of the viscoelastic modulus is very important. However, experimental characterization of the frequency-dependent modulus, carried out through different standard procedures, still presents some complexities; then possible alternative approaches are desirable. For example, experimental investigation of viscoelastic beam dynamics would be challenging, especially for the intrinsic simplicity of this kind of test. This is why a deep understanding of damping mechanisms in viscoelastic beams is found to be a quite important task to better predict their dynamics. With the aim to enlighten damping properties in such structures, an analytical study of the transversal vibrations of a viscoelastic beam is presented in this article. Some dimensionless parameters are defined, depending on the material properties and the beam geometry, which enable to accurately design the beam dynamics. In this way, by properly tuning such disclosed parameters, for example the dimensionless beam length or a chosen material, it is possible to enhance or suppress some resonant peaks, one at a time or more simultaneously. This is a remarkable possibility to efficiently control damping in these structures, and the results presented in this article may help in elucidating experimental procedures for the characterization of viscoelastic materials.

Characterization of intergranular cuprous oxide in polycrystalline YBa2Cu3O7-x

1988 ◽  
Vol 46 ◽  
pp. 880-881
Author(s):  
Bradley L. Thiel ◽  
Chan Han R. P. ◽  
Kurosky L. C. Hutter ◽  
I. A. Aksay ◽  
Mehmet Sarikaya
Keyword(s):  
Grain Boundary ◽  
Cuprous Oxide ◽  
Room Temperature ◽  
Boundary Phase ◽  
Spectroscopic Techniques ◽  
Transition Width ◽  
Practical Applications ◽  
Thin Foils ◽  
Superconducting Oxides

The identification of extraneous phases is important in understanding of high Tc superconducting oxides. The spectroscopic techniques commonly used in determining the origin of superconductivity (such as RAMAN, XPS, AES, and EXAFS) are surface-sensitive. Hence a grain boundary phase several nanometers thick could produce irrelevant spectroscopic results and cause erroneous conclusions. The intergranular phases present a major technological consideration for practical applications. In this communication we report the identification of a Cu2O grain boundary phase which forms during the sintering of YBa2Cu3O7-x (1:2:3 compound).Samples are prepared using a mixture of Y2O3. CuO, and BaO2 powders dispersed in ethanol for complete mixing. The pellets pressed at 20,000 psi are heated to 950°C at a rate of 5°C per min, held for 1 hr, and cooled at 1°C per min to room temperature. The samples show a Tc of 91K with a transition width of 2K. In order to prevent damage, a low temperature stage is used in milling to prepare thin foils which are then observed, using a liquid nitrogen holder, in a Philips 430T at 300 kV.

Processing and characterization of YBa2Cu3O7−x/Ag composites

1990 ◽  
Vol 48 (4) ◽  
pp. 46-47
Author(s):  
Jafar Javadpour ◽  
Bradley L. Thiel ◽  
Sarikaya Mehmet ◽  
Ilhan A. Aksay
Keyword(s):  
Composite System ◽  
Precursor Solution ◽  
Microstructural Development ◽  
Superconducting Properties ◽  
Practical Applications ◽  
Nitrate Precursor ◽  
Cold Pressed ◽  
Tape Cast ◽  
Composite Samples

Practical applications of bulk YBa2Cu3O7−x materials have been limited because of their inadequate critical current density (jc) and poor mechanical properties. Several recent reports have indicated that the addition of Ag to the YBa2Cu3O7−x system is beneficial in improving both mechanical and superconducting properties. However, detailed studies concerning the effect of Ag on the microstructural development of the cermet system have been lacking. Here, we present some observations on the microstructural evolution in the YBa2Cu3O7−x/Ag composite system.The composite samples were prepared by mixing various amounts (2.5 - 50 wt%) AgNO3 in the YBa2Cu3O7−x nitrate precursor solution. These solutions were then spray dried and the resulting powders were either cold pressed or tape cast. The microstructures of the sintered samples were analyzed using SEM (Philips 515) and an analytical TEM (Philips 430T).The SEM micrographs of the compacts with 2.5 and 50 wt% Ag addition sintered at 915°C (below the melting point of Ag) for 1 h in air are displayed in Figs. 1 and 2, respectively.

scholarly journals A New Statistical Biomechanics Modeling of Physical and Biochemical Bone Strength Parameters

2000 ◽  
Author(s):  
Alfred B. O. Soboyejo ◽  
Karl E. Nestor
Keyword(s):  
Bone Strength ◽  
Biochemical Parameters ◽  
Broiler Chickens ◽  
Management Practices ◽  
Physical Parameters ◽  
Structural Failure ◽  
Practical Applications ◽  
Good Management ◽  
Biomechanical Parameters

Abstract New multiparameter biomechanics models are developed in this work for the characterization of bone strengths in broiler chickens and turkeys, as functions of the major physical and biochemical parameters, which can contribute to mechanical properties of bone strengths in these birds, under good management practices. Theoretical and experimental methods have been developed in this study to model bone strength as functions of (a) the physical parameters only and (b) the biochemical parameters only, which can affect bone strength. The choice of any particular methodology will depend on the availability of either the physical or biochemical parameters, which can be obtained from experimental data. Possible useful practical applications of the statistical biomechanics principles developed in this technical paper, particularly in the field of bone strength enhancement in turkeys and broiler chickens will be discussed. In view of the problems described, the major objectives of the present study are as follows: (1) To develop new multiparameter biomechanics models for the characterization of bone strengths in turkeys and broiler chickens as functions of the major physical only, or biomechanical parameters only, which can contribute to bone strength in these birds, under conditions of good management of these birds. This study will consider only the compressive buckling as the mode of structural failure in the cellular material of the bone. (2) To highlight briefly the possible practical applications of the statistical biomechanics principles, which will be developed in this study to the genetic improvement of bone strengths in broiler chickens and turkeys.

scholarly journals Regeneration: Why junk DNA might matter

2018 ◽  
Author(s):  
Carlos Díaz-Castillo
Keyword(s):  
Natural Variation ◽  
Spatial Organization ◽  
Natural Phenomena ◽  
Collective Knowledge ◽  
Junk Dna ◽  
Research Fields ◽  
Biological Variables ◽  
The Individual

The ability of certain natural species to restore or regenerate missing structures has been a recurrent source of inspiration to forge our collective knowledge, from being used to adorn mythological figures with superhuman powers to permitting controlled reproducible observations that help setting the bases of entire research fields such as experimental biology and regenerative medicine. In spite of being one of the oldest natural phenomena under study, what makes certain species able or unable to regenerate missing parts is still largely a mystery. Recent advancements towards the highly detailed characterization of the sequence, the spatial organization, and the expression of genomes is offering a new standpoint to address the study of the natural variation in regenerative responses. An intriguing observation that has not yet conveniently pursued is that species with remarkable regenerative abilities tend to have genomes loaded with junk DNA (jDNA), i.e., genetic elements presumed to be useless for the benefit of the individual, whereas species for taxa with limited regenerative abilities tend to have jDNA-poor genomes. Here, I use existing knowledge on the role of jDNA as genome evolution facilitator and its non-random chromosome and nuclear distributions to speculate about two non-excluding ways through which the variation in jDNA genomic content might end up enhancing or limiting regenerative responses. The present piece aims to go beyond the confines of correlational studies between biological variables and to lay sensible conceptual grounds for future hypothesis-driven attempts to substantiate the genomic determinants of the natural variation of regenerative responses.

Implementation, Characterization and Application of Path Changing Switch based Arbiter PUF on FPGA as a lightweight Security Primitive for IoT

2022 ◽  
Vol 27 (3) ◽  
pp. 1-26
Author(s):  
Mahabub Hasan Mahalat ◽  
Suraj Mandal ◽  
Anindan Mondal ◽  
Bibhash Sen ◽  
Rajat Subhra Chakraborty
Keyword(s):  
Complete Characterization ◽  
Effect Of Temperature ◽  
Practical Applications ◽  
Gate Arrays ◽  
Heterogeneous Technologies ◽  
Field Programmable ◽  
Arbiter Puf ◽  
Programmable Gate Arrays ◽  
Secure Authentication

Secure authentication of any Internet-of-Things (IoT) device becomes the utmost necessity due to the lack of specifically designed IoT standards and intrinsic vulnerabilities with limited resources and heterogeneous technologies. Despite the suitability of arbiter physically unclonable function (APUF) among other PUF variants for the IoT applications, implementing it on field-programmable gate arrays (FPGAs) is challenging. This work presents the complete characterization of the path changing switch (PCS) 1 based APUF on two different families of FPGA, like Spartan-3E (90 nm CMOS) and Artix-7 (28 nm CMOS). A comprehensive study of the existing tuning concept for programmable delay logic (PDL) based APUF implemented on FPGA is presented, leading to establishment of its practical infeasibility. We investigate the entropy, randomness properties of the PCS based APUF suitable for practical applications, and the effect of temperature variation signifying the adequate tolerance against environmental variation. The XOR composition of PCS based APUF is introduced to boost performance and security. The robustness of the PCS based APUF against machine learning based modeling attack is evaluated, showing similar characteristics as the conventional APUF. Experimental results validate the efficacy of PCS based APUF with a little hardware footprint removing the paucity of lightweight security primitive for IoT.

Synthesis and Characterization of Zirconium Metal Complexes Derived from Benzene-1, 4-dicarboxylic acid

2020 ◽  
Vol 42 (6) ◽  
pp. 919-919
Author(s):  
Hafiz Muhammad Arshad Hafiz Muhammad Arshad ◽  
Shazia Khurshid Shazia Khurshid ◽  
Shahzad Sharif Shahzad Sharif ◽  
Muhammad Ali Muhammad Ali ◽  
Muhammad Dilshad Muhammad Dilshad ◽  
...  
Keyword(s):  
Metal Complexes ◽  
Dicarboxylic Acid ◽  
Terephthalic Acid ◽  
Research Work ◽  
Early Developmental Stage ◽  
Practical Applications ◽  
Secondary Building Units ◽  
Ft Ir ◽  
Zirconium Metal

Amongst organo-metallic frameworks (OMFs), the metallic framework having Zirconium metal indicate fascinating structural properties and excellent stability. Such organo-metallic frameworks (OMFs) function as a potential material for practical application. Even though these particular organo-metallic frameworks are in the early developmental stage but considerable advancements have been carried out recently. We studied the characterization of zirconium-based organo-metallic frameworks. We built Zr-based OMFs by four different synthetic ways. Initially, upgraded preparation under green and commercially feasible conditions has been carried out by modifying Zr-OMFs. Zirconium based OMFs having different structures are then classified and explained based on various organic ligands and zirconium-based secondary building units. We have synthesized the zirconium metal complexes; they have been characterized on the bases of FT-IR and CHNS analyzer. FT-IR results show binding of metal with the Benzene-1, 4-dicarboxylic acid [C6H4 (COOH) 2]. Zirconium metal can bind with the organic substances for the construction of a variety of complexes. From my research work, it is concluded that zirconium metal forms a polymeric complex with terephthalic acid. In which oxygen atoms of Terephthalic acid form bridging structure with the zirconium metal. Our study based on a particular type of OMF is likely expected to present guidance for in-depth exploration of OMFs towards practical applications. It is concluded that the metal-organic frameworks (MOFs) of zirconium metal have many applications in the field of chemistry, biology and other numerous fields of science

"THE WHOLE KABARDA WILL GREET THIS ACT WITH A SENSE OF GREAT MORAL SATISFACTION...". ARTICLE OF G. BAYEV "ABOUT JOINING OF MINOR KABARDA TO THE GREAT KABARDA

Kavkazologiya ◽  
2021 ◽  
pp. 86-107
Author(s):  
D.N. PRASOLOV ◽  
Keyword(s):  
Deep Understanding ◽  
Cultural Development ◽  
Information Support ◽  
The Public ◽  
Economic Problems ◽  
Explanatory Note ◽  
History Of ◽  
Economic Modernization ◽  
Detailed Work

In publicist writings of G. Bayev were reflected many issues of socio-cultural development of the peoples of the Terek region in the second half of XIX – early XX centuries. Considerable attention Ossetian public figure paid to social and economic problems of peoples of Nalchik district. In particular they were treated in a context of functioning of their self-government – Congress of entrusted of the Great and Minor Kabarda and Five mountain societies. In January 1905, nine villages of Minor Kabarda concluded with G. Bayev an agreement to represent their interests in the petition to restore the unity of Great and Minor Kabarda within the Nalchik district. In the course of fulfilling of this task G. Bayev prepared an explanatory note and organised its information support. The basic positions of the petition's substantiation were stated in the article published in several issues of "Pyatigorskiy listok" at the beginning of June 1905. By its substantive qualities the material represented a detailed work on the history of the public self-government of Kabardians in the genre of zemstvo journalism. G. Bayev's systematic characterization of cultural and historical preconditions and administrative expediency of reunion of Great and Minor Kabarda convincingly testified to a deep understanding of socially significant tasks and the ways of their achievement necessary for socio-political and economic modernization of the territory. The result of his petition was the order of the viceroy of Caucasus I.I. Vorontsov-Dashkov of August 24, 1905 to incorporate the villages of Minor Kabarda to the Nalchik okrug. The publication of G. Bayev's article introduces into scientific circulation an informative source testifying to the formation of constructive skills of socio-state interaction in political culture of peoples of Terskaya oblast’ initiated by representatives of national intelligentsia of the region.

Some new approaches to probability distributions

1980 ◽  
Vol 12 (04) ◽  
pp. 903-921 ◽  
Author(s):  
S. Kotz ◽  
D. N. Shanbhag
Keyword(s):  
Probability Distributions ◽  
Random Variables ◽  
Representation Theorems ◽  
Practical Applications ◽  
New Approaches ◽  
Characterization Of Distributions ◽  
Stability Theorems ◽  
Conditional Expectations

We develop some approaches to the characterization of distributions of real-valued random variables, useful in practical applications, in terms of conditional expectations and hazard measures. We prove several representation theorems generalizing earlier results, and establish stability theorems for two general characteristics introduced in this paper.

scholarly journals Fabrication of Ultra-High Aspect Ratio (>420:1) Al2O3 Nanotube Arraysby Sidewall TransferMetal Assistant Chemical Etching

Micromachines ◽  
2020 ◽  
Vol 11 (4) ◽  
pp. 378 ◽  
Author(s):  
Hailiang Li ◽  
Changqing Xie
Keyword(s):  
Aspect Ratio ◽  
High Aspect Ratio ◽  
Chemical Etching ◽  
Atomic Layer ◽  
Nanotube Arrays ◽  
Al2o3 Layer ◽  
Practical Applications ◽  
Aspect Ratios ◽  
Layer Deposition

We report a robust, sidewall transfer metal assistant chemical etching scheme for fabricating Al2O3 nanotube arrays with an ultra-high aspect ratio. Electron beam lithography followed by low-temperature Au metal assisted chemical etching (MacEtch) is used to pattern high resolution, high aspect ratio, and vertical silicon nanostructures, used as a template. This template is subsequently transferred by an atomic layer deposition of the Al2O3 layer, followed by an annealing process, anisotropic dry etching of the Al2O3 layer, and a sacrificial silicon template. The process and characterization of the Al2O3 nanotube arrays are discussed in detail. Vertical Al2O3 nanotube arrays with line widths as small as 50 nm, heights of up to 21 μm, and aspect ratios up to 420:1 are fabricated on top of a silicon substrate. More importantly, such a sidewall transfer MacEtch approach is compatible with well-established silicon planar processes, and has the benefits of having a fully controllable linewidth and height, high reproducibility, and flexible design, making it attractive for a broad range of practical applications.

Integrating the whole from the sum of the parts: vignettes in computational biology

2017 ◽  
Vol 1 (3) ◽  
pp. 241-243
Author(s):  
Jeffrey Skolnick
Keyword(s):  
Deep Learning ◽  
Drug Discovery ◽  
Synthetic Biology ◽  
Personalized Medicine ◽  
Computational Biology ◽  
Biological Systems ◽  
Deep Understanding ◽  
Biological Processes ◽  
Practical Applications ◽  
Biological Variables

As is typical of contemporary cutting-edge interdisciplinary fields, computational biology touches and impacts many disciplines ranging from fundamental studies in the areas of genomics, proteomics transcriptomics, lipidomics to practical applications such as personalized medicine, drug discovery, and synthetic biology. This editorial examines the multifaceted role computational biology plays. Using the tools of deep learning, it can make powerful predictions of many biological variables, which may not provide a deep understanding of what factors contribute to the phenomena. Alternatively, it can provide the how and the why of biological processes. Most importantly, it can help guide and interpret what experiments and biological systems to study.

Sign in / Sign up

Export Citation Format

Share Document