Dzhanibekov effect in a physics classroom

2021 ◽  
Vol 57 (1) ◽  
pp. 015019
Author(s):  
O Lozovenko ◽  
Yu Minaiev ◽  
R Lutai
Keyword(s):  
Experimental Research ◽  
Main Idea ◽  
Upward Flow ◽  
Research Projects ◽  
Moments Of Inertia ◽  
Principal Moments Of Inertia ◽  
Novel Approach ◽  
Spinning Top ◽  
Rotational Phase ◽  
External Form

Abstract The purpose of this publication is to present a novel approach to the demonstration of the Dzhanibekov effect. The main idea of our version is to use a lightweight spinning top of a spherical external form but distinct principal moments of inertia floating in the upward flow of air. As a result, the Dzhanibekov effect can be easily demonstrated anywhere on Earth: in any classroom, or even in the ‘home-lab’. The proposed demonstration allows one to observe the periodical flipping motion of the asymmetrical top with the clearly seen quasi-stable rotational phase. It may also become the base for various theoretical and experimental research projects for students.

scholarly journals Method for assessment of matching of total ankle joint endoprostheses based on CT data

2020 ◽  
Vol 6 (3) ◽  
pp. 396-397
Author(s):  
Heiner Martin ◽  
Josephine Wittmüß ◽  
Thomas Mittlmeier ◽  
Niels Grabow
Keyword(s):  
Cross Sections ◽  
Spline Functions ◽  
Moments Of Inertia ◽  
Cad System ◽  
Principal Moments Of Inertia ◽  
Principal Axes ◽  
Ct Data ◽  
The One ◽  
Relative Differences ◽  
Systemic Design

AbstractThe investigation of matching of endoprosthesis tibial components to the bone cross section is of interest for the manufacturer as well as for the surgeon. On the one hand, a systemic design of the prosthesis and the assortment is possible, on the other hand, a better matching implantation is enabled on the basis of experience of this study. CT sections were segmented manually using a CAD system and fitted by spline functions, then superseded with cross sections of the tibial component of a modified Hintermann H3 prosthesis. The principal moments of inertia, the direction of the principal axes and the area of the section were evaluated. Based on the relative differences of the principal moments of inertia, recommendations for application of the different prosthesis size and its selection with the surgery can be made.

scholarly journals Principles of adaptive element spacing in linear array antennas

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Tanzeela Mitha ◽  
Maria Pour
Keyword(s):  
Antenna Arrays ◽  
Communication Systems ◽  
Linear Array ◽  
Main Idea ◽  
Phase Center ◽  
Array Configuration ◽  
Array Antennas ◽  
Center Location ◽  
Novel Approach ◽  
Array Performance

AbstractA novel approach to linear array antennas with adaptive inter-element spacing is presented for the first time. The main idea is based upon electronically displacing the phase center location of the antenna elements, which determine their relative coordinates in the array configuration. This is realized by employing dual-mode microstrip patch antennas as a constitutive element, whose phase center location can be displaced from its physical center by simultaneously exciting two modes. The direction and the amount of displacement is controlled by the amplitude and phase of the modes at the element level. This in turn facilitates reconfiguring the inter-element spacing at the array level. For instance, a uniformly-spaced array could be electronically transformed into a non-uniform one without any mechanical means. The proposed idea is demonstrated in two- and three-element linear antenna arrays. The technique has the potential to control the radiation characteristics such as sidelobe levels, position of the nulls, and the beamwidths in small arrays, which are useful for adaptively controlling the array performance in emerging wireless communication systems and radars.

scholarly journals Reflections on the Ethics of Social Experimentation

2015 ◽  
Vol 6 (1) ◽  
Author(s):  
Macartan Humphreys
Keyword(s):  
Public Policy ◽  
Adverse Effects ◽  
Experimental Research ◽  
Social Benefits ◽  
Research Projects ◽  
Ethical Guidelines ◽  
Social Scientists ◽  
Standard Procedures ◽  
Power Differentials ◽  
Social Experimentation

AbstractSocial scientists are increasingly engaging in experimental research projects of importance for public policy in developing areas. While this research holds the possibility of producing major social benefits, it may also involve manipulating populations, often without consent, sometimes with potentially adverse effects, and often in settings with obvious power differentials between researcher and subject. Such research is currently conducted with few clear ethical guidelines. In this paper I discuss research ethics as currently understood in this field, highlighting the limitations of standard procedures and the need for the construction of appropriate ethics, focusing on the problems of determining responsibility for interventions and assessing appropriate forms of consent.

scholarly journals A Novel Approach for Robust Perceptual Image Hashing

2021 ◽  
Vol 14 (3) ◽  
pp. 38
Author(s):  
Azhar Hadmi ◽  
Awatif Rouijel
Keyword(s):  
Side Information ◽  
Main Idea ◽  
Jpeg Compression ◽  
Image Hashing ◽  
Novel Approach ◽  
Perceptual Hash ◽  
Short Signature ◽  
Robust Image ◽  
Tampered Image ◽  
The Stability

Perceptual image hashing system generates a short signature called perceptual hash attached to an image before transmission and acts as side information for analyzing the trustworthiness of the received image. In this paper, we propose a novel approach to improve robustness for perceptual image hashing scheme for generating a perceptual hash that should be resistant to content-preserving manipulations, such as JPEG compression and Additive white Gaussian noise (AWGN) also should differentiate the maliciously tampered image and its original version. Our algorithm first constructs a robust image, derived from the original input by analyzing the stability of the extracted features and improving their robustness. From the robust image, which does perceptually resemble the original input, we further extract the final robust features. Next, robust features are suitably quantized allowing the generation of the final perceptual hash using the cryptographic hash function SHA1. The main idea of this paper is to transform the original image into a more robust one that allows the extraction of robust features. Generation of the robust image turns out be quite important since it introduces further robustness to the perceptual image hashing system. The paper can be seen as an attempt to propose a general methodology for more robust perceptual image hashing. The experimental results presented in this paper reveal that the proposed scheme offers good robustness against JPEG compression and Additive white Gaussian noise.

The whirling of a spinning top

1950 ◽  
Vol 2 (1) ◽  
pp. 9-14
Author(s):  
J. Morris
Keyword(s):  
High Speed ◽  
Moments Of Inertia ◽  
Prime Movers ◽  
Rotating Shafts ◽  
The Common ◽  
The Stability ◽  
Spinning Top

SummaryThis paper has been compiled because of the applicability of the treatment of the stability of the motion of the common spinning top to the problem of the whirling of rotating shafts, carrying loads of appreciable moments of inertia. This problem is assuming renewed interest and importance, especially in the drives of contra-propeller systems and the more recent high speed prime movers.

Interactive Models for Virtual Enterprises

2011 ◽  
pp. 316-333
Author(s):  
Håvard D. Jorgensen ◽  
John Krogstie
Keyword(s):  
Case Studies ◽  
Ad Hoc ◽  
Virtual Enterprises ◽  
Major Result ◽  
Research Projects ◽  
Model Driven ◽  
Visual Model ◽  
Novel Approach ◽  
Interactive Models ◽  
And Performance

This chapter presents a novel approach to the development, integration, and operation of virtual enterprises (VEs). The approach is based on the idea of interactive models. An interactive model is a visual model of enterprise aspects that can be viewed, traversed, analyzed, simulated, adapted, and executed by the participants of the VE. The approach has been developed in several research projects, where experiences from industrial case studies are used as a basis for validation and further enhancement. A major result of this work is the model-driven infrastructure that integrates and supports VEs. The main innovative contributions of this infrastructure include concurrent modelling, metamodelling, management and performance of work, integrated support for ad hoc and structured processes, and customizable model- and process-driven integration.

Explaining Algorithms

2011 ◽  
pp. 2261-2279
Author(s):  
Tomasz Muldner ◽  
Elhadi Shakshuki
Keyword(s):  
Distance Education ◽  
Main Idea ◽  
Top Down ◽  
Levels Of Abstraction ◽  
Visualization System ◽  
Client Server ◽  
Novel Approach ◽  
Visualization Systems ◽  
Explanation System ◽  
Server Architecture

This article presents a novel approach for explaining algorithms that aims to overcome various pedagogical limitations of the current visualization systems. The main idea is that at any given time, a learner is able to focus on a single problem. This problem can be explained, studied, understood, and tested, before the learner moves on to study another problem. Toward this end, a visualization system that explains algorithms at various levels of abstraction has been designed and implemented. In this system, each abstraction is focused on a single operation from the algorithm using various media, including text and an associated visualization. The explanations are designed to help the user to understand basic properties of the operation represented by this abstraction, for example its invariants. The explanation system allows the user to traverse the hierarchy graph, using either a top-down (from primitive operations to general operations) approach or a bottom-up approach. Since the system is implemented using a client-server architecture, it can be used both in the classroom setting and through distance education.

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