6,835,527 research outputs found
Small digital recording head has parallel bit channels, minimizes cross talk
A small digital recording head consists of closely spaced parallel wires, imbedded in a ferrite block to concentrate the magnetic flux. Parallel-recorded information bits are converted into serial bits on moving magnetic tape and cross talk is suppressed
A Model of the Double Magnetic Cycle of the Sun
It has been argued that the solar magnetic cycle consists of two main
periodic components: a low-frequency component (Hale's 22-year cycle) and a
high-frequency component (quasi-biennial cycle). The existence of the double
magnetic cycle on the Sun is confirmed using Stanford, Mount Wilson and Kitt
Peak magnetograph data from 1976 to 1996 (solar cycles 21 and 22). In the frame
of the Parker's dynamo theory a model of the double magnetic cycle is
presented. This model is based on the idea of two dynamo sources separated in
space. The first source of the dynamo action is located near the bottom of the
convection zone, and the second operates near the top. The model is formulated
in terms of two coupled systems of non-linear differential equations. It is
demonstrated that in the case of weak interaction between the two dynamo
sources the basic features of the double magnetic cycle such as existence of
two component and observed temporal variations of high-frequency component can
be reproduced.Comment: 6 pages, 2 figure
Entrepreneurial learning in family business
This paper draws on a situated learning perspective to examine learning in the context of family business. It draws on the experience of two generations, the founders of a business and their successors from the next generation of the same family. In-depth interviews provide an insight into learning about business as articulated by families who own and manage a business spanning more than one generation. The study relies on their narratives as a way of knowing and as a form of communication. Narrative interpretation throws into relief aspects of learning in the context of a family business. A review of the entrepreneurial learning literature offers theoretical insights but it also highlights the existing research focus on the individual, predominately male, entrepreneur. This paper challenges that assumption and reveals the complex intergenerational dynamics of family and business. It contributes towards a re-conceptualisation of entrepreneurial learning as socially situated, embedded in participation in the social practices of the family and the business
A New Superconformal Mechanics
In this paper we propose a new supersymmetric extension of conformal
mechanics. The Grassmannian variables that we introduce are the basis of the
forms and of the vector-fields built over the symplectic space of the original
system. Our supersymmetric Hamiltonian itself turns out to have a clear
geometrical meaning being the Lie-derivative of the Hamiltonian flow of
conformal mechanics. Using superfields we derive a constraint which gives the
exact solution of the supersymmetric system in a way analogous to the
constraint in configuration space which solved the original non-supersymmetric
model. Besides the supersymmetric extension of the original Hamiltonian, we
also provide the extension of the other conformal generators present in the
original system. These extensions have also a supersymmetric character being
the square of some Grassmannian charge. We build the whole superalgebra of
these charges and analyze their closure. The representation of the even part of
this superalgebra on the odd part turns out to be integer and not spinorial in
character.Comment: Superfield re-define
Simultaneous processing of vibration test data
Data from record tracks of all accelerometers is injected simultaneously into electronic circuits which convert inputs into single, composite graphical representation. Three adequate methods of processing data: peak acceleration at a frequency, average of all channels, and quad-mean of all channels
An Introduction to Pure Spinor Superstring Theory
In these lecture notes presented at the 2015 Villa de Leyva Summer School, we
give an introduction to superstring theory. We begin by studying the particle
and superparticle in order to get a better understanding on the superstring
side. Afterwards, we review the pure spinor formalism and end by computing the
scattering amplitude for three gravitons at tree-level.Comment: Villa de Leyva Summer School 2015 proceedings, 28 pages, 2 figure
A Cooperative Emergency Navigation Framework using Mobile Cloud Computing
The use of wireless sensor networks (WSNs) for emergency navigation systems
suffer disadvantages such as limited computing capacity, restricted battery
power and high likelihood of malfunction due to the harsh physical environment.
By making use of the powerful sensing ability of smart phones, this paper
presents a cloud-enabled emergency navigation framework to guide evacuees in a
coordinated manner and improve the reliability and resilience in both
communication and localization. By using social potential fields (SPF),
evacuees form clusters during an evacuation process and are directed to
egresses with the aid of a Cognitive Packet Networks (CPN) based algorithm.
Rather than just rely on the conventional telecommunications infrastructures,
we suggest an Ad hoc Cognitive Packet Network (AHCPN) based protocol to prolong
the life time of smart phones, that adaptively searches optimal communication
routes between portable devices and the egress node that provides access to a
cloud server with respect to the remaining battery power of smart phones and
the time latency.Comment: This document contains 8 pages and 3 figures and has been accepted by
ISCIS 2014 (29th International Symposium on Computer and Information
Sciences
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