5,654 research outputs found
THE IMPACT OF HISTORICAL AND REGIONAL LINKAGES ON FREE TRADE IN THE AMERICAS: A GRAVITY MODEL ANALYSIS ACROSS SECTORS
This paper estimates the impact of regional linkages (i.e. regional trading agreements) and historical linkages (i.e. neo-colonial trade ties) on trade pattern in the Western Hemisphere using the gravity model of international trade. The estimation is made at the aggregate trade level as well as on the disaggregated level by using trade data corresponding to food products and manufactured goods respectively. The evidence suggests that significant distortions of trade patterns due to regional and historical linkages exist. It seems that smaller economies are more receptive to the effects of regionalism than larger ones and that the food sector is more affected by distortions than the manufactured goods sector.International Relations/Trade,
Complexity Reduction for Parameter-Dependent Linear Systems
We present a complexity reduction algorithm for a family of
parameter-dependent linear systems when the system parameters belong to a
compact semi-algebraic set. This algorithm potentially describes the underlying
dynamical system with fewer parameters or state variables. To do so, it
minimizes the distance (i.e., H-infinity-norm of the difference) between the
original system and its reduced version. We present a sub-optimal solution to
this problem using sum-of-squares optimization methods. We present the results
for both continuous-time and discrete-time systems. Lastly, we illustrate the
applicability of our proposed algorithm on numerical examples
Design of State-based Schedulers for a Network of Control Loops
For a closed-loop system, which has a contention-based multiple access
network on its sensor link, the Medium Access Controller (MAC) may discard some
packets when the traffic on the link is high. We use a local state-based
scheduler to select a few critical data packets to send to the MAC. In this
paper, we analyze the impact of such a scheduler on the closed-loop system in
the presence of traffic, and show that there is a dual effect with state-based
scheduling. In general, this makes the optimal scheduler and controller hard to
find. However, by removing past controls from the scheduling criterion, we find
that certainty equivalence holds. This condition is related to the classical
result of Bar-Shalom and Tse, and it leads to the design of a scheduler with a
certainty equivalent controller. This design, however, does not result in an
equivalent system to the original problem, in the sense of Witsenhausen.
Computing the estimate is difficult, but can be simplified by introducing a
symmetry constraint on the scheduler. Based on these findings, we propose a
dual predictor architecture for the closed-loop system, which ensures
separation between scheduler, observer and controller. We present an example of
this architecture, which illustrates a network-aware event-triggering
mechanism.Comment: 17 pages, technical repor
Recommended from our members
A Cultural Criminology of ‘New’ Jihad: Insights from Propaganda Magazines
The backgrounds and modus operandi of more recent jihadi terrorists tend to share factors and characteristics more typically associated with non-political violence such as mass- killings and gang violence. Their attacks, moreover, seem to have been precipitated not by the direct instructions of a formal hierarchy but by the encouragement of propaganda produced and disseminated by networked, media-savvy terrorist groups. It is necessary to explain how these ‘recruitment’ efforts work. Cultural criminology with its understanding of the relationship between mediated meaning and individual experience, can provide such an analysis. The paper presents a qualitative document analysis of 32 propaganda magazines produced by the Islamic State and Al-Qaeda. It demonstrates that they contain significantly more than religious rhetoric and military strategy. Rather, they are part of a process that crystalizes a jihadi subculture that appeals to disaffected and/or marginalized, excitement- seeking youths. The magazines cultivate violence by constructing a militarized style that celebrates outlaw status, where violence is eroticized and aestheticized. They idealize the notion of a jihadi terrorist that is tough and willing to commit brutal violence. The lifestyle portrayed offers the possibility of heroism, excitement, belonging and imminent fame, themes often espoused by conventional, Western consumer culture. The magazines occasionally draw on street jargon, urban music, fashion, films and video games. The subcultural model of jihadi propaganda we explicate provides a novel way of understanding terrorist recruiting tactics and motivations that are not necessarily in opposition to contemporary conventional criminal and ‘mainstream’ cultures, but in resonance with them
Absolute Properties of the Eclipsing Binary Star V501 Herculis
V501 Her is a well detached G3 eclipsing binary star with a period of
8.597687 days for which we have determined very accurate light and
radial-velocity curves by using robotic telescopes. Results of these data
indicate that the component stars have masses of 1.269 +/- 0.004 and 1.211 +/-
0.003 solar masses, radii of 2.001 +/- 0.003 and 1.511 +/- 0.003 solar radii,
and temperatures of 5683 +/- 100K and 5720 +/- 100K, respectively. Comparison
with the Yonsei-Yale series of evolutionary models results in good agreement at
an age of about 5.1 Gyr for a somewhat metal rich composition. Those models
indicate that the more massive, larger, slightly cooler star is just beyond
core hydrogen exhaustion while the less massive, smaller, slightly hotter star
has not quite reached core hydrogen exhaustion. The orbit is not yet
circularized, and the components are rotating at or near their
pseudosynchronous velocities. The distance to the system is 420 +/- 30 pc
- …