1,324 research outputs found
AdSplit: Separating smartphone advertising from applications
A wide variety of smartphone applications today rely on third-party
advertising services, which provide libraries that are linked into the hosting
application. This situation is undesirable for both the application author and
the advertiser. Advertising libraries require additional permissions, resulting
in additional permission requests to users. Likewise, a malicious application
could simulate the behavior of the advertising library, forging the user's
interaction and effectively stealing money from the advertiser. This paper
describes AdSplit, where we extended Android to allow an application and its
advertising to run as separate processes, under separate user-ids, eliminating
the need for applications to request permissions on behalf of their advertising
libraries.
We also leverage mechanisms from Quire to allow the remote server to validate
the authenticity of client-side behavior. In this paper, we quantify the degree
of permission bloat caused by advertising, with a study of thousands of
downloaded apps. AdSplit automatically recompiles apps to extract their ad
services, and we measure minimal runtime overhead. We also observe that most ad
libraries just embed an HTML widget within and describe how AdSplit can be
designed with this in mind to avoid any need for ads to have native code
Entanglement dynamics following a sudden quench: an exact solution
We present an exact and fully analytical treatment of the entanglement
dynamics for an isolated system of coupled oscillators following a sudden
quench of the system parameters. The system is analyzed using the solutions of
the time dependent Schrodinger's equation, which are obtained by solving the
corresponding nonlinear Ermakov equations. The entanglement entropies exhibit a
multi-oscillatory behaviour, where the number of dynamically generated time
scales increases with . The harmonic chains exhibit entanglement revival and
for larger values of , we find near-critical logarithmic scaling for
the entanglement entropy, which is modulated by a time dependent factor. The
case is equivalent to the two site Bose-Hubbard model in the tunneling
regime, which is amenable to empirical realization in cold atom systems.Comment: Figure for large N added, discussion related with near critical
scaling behavior adde
Quire: Lightweight Provenance for Smart Phone Operating Systems
Smartphone apps often run with full privileges to access the network and
sensitive local resources, making it difficult for remote systems to have any
trust in the provenance of network connections they receive. Even within the
phone, different apps with different privileges can communicate with one
another, allowing one app to trick another into improperly exercising its
privileges (a Confused Deputy attack). In Quire, we engineered two new security
mechanisms into Android to address these issues. First, we track the call chain
of IPCs, allowing an app the choice of operating with the diminished privileges
of its callers or to act explicitly on its own behalf. Second, a lightweight
signature scheme allows any app to create a signed statement that can be
verified anywhere inside the phone. Both of these mechanisms are reflected in
network RPCs, allowing remote systems visibility into the state of the phone
when an RPC is made. We demonstrate the usefulness of Quire with two example
applications. We built an advertising service, running distinctly from the app
which wants to display ads, which can validate clicks passed to it from its
host. We also built a payment service, allowing an app to issue a request which
the payment service validates with the user. An app cannot not forge a payment
request by directly connecting to the remote server, nor can the local payment
service tamper with the request
Non-rotating and rotating neutron stars in the extended field theoretical model
We study the properties of non-rotating and rotating neutron stars for a new
set of equations of state (EOSs) with different high density behaviour obtained
using the extended field theoretical model. The high density behaviour for
these EOSs are varied by varying the meson self-coupling and
hyperon-meson couplings in such a way that the quality of fit to the bulk
nuclear observables, nuclear matter incompressibility coefficient and
hyperon-nucleon potential depths remain practically unaffected. We find that
the largest value for maximum mass for the non-rotating neutron star is
. The radius for the neutron star with canonical mass is km provided only those EOSs are considered for which maximum mass is
larger than as it is the lower bound on the maximum mass measured
so far. Our results for the very recently discovered fastest rotating neutron
star indicate that this star is supra massive with mass and
circumferential equatorial radius km.Comment: 28 pages, 12 figures. Phys. Rev. C (in press
Annihilation of vortex dipoles in an Oblate Bose-Einstein Condensate
We theoretically explore the annihilation of vortex dipoles, generated when
an obstacle moves through an oblate Bose-Einstein condensate, and examine the
energetics of the annihilation event. We show that the gray soliton, which
results from the vortex dipole annihilation, is lower in energy than the vortex
dipole. We also investigate the annihilation events numerically and observe
that the annihilation occurs only when the vortex dipole overtakes the obstacle
and comes closer than the coherence length. Furthermore, we find that the noise
reduces the probability of annihilation events. This may explain the lack of
annihilation events in experimental realizations.Comment: 8 pages and 9 figure
Integration of Service-Learning into Civil and Environmental Engineering Curriculum
Service-learning is defined as integrating the community service experience of students with their academic study so that learning is enhanced. The level of student participation in community service is at an all time high as students feel the need to confront today\u27s technical and societal problems. However, service-learning is more than community service or volunteerism. Service-learning as defined above, integrates the community service experience with the student’s academic study (note the hyphen in service-learning means that both are considered equal). This enhances learning which is a fundamental goal of colleges and universities. Boyer highlights the need for service-learning stating that At no time in our history has the need been greater for connecting the work of the academy to the social and environmental changes beyond the campus. Service-learning is a campus wide learning pedagogy including a range of disciplines and has been implemented at over 600 institutions; however, not as widely implemented in engineering and science. A noteworthy contribution in the engineering education, is the Engineering Projects in Community Service (EPICS) program at Purdue University (http://epics.ecn.purdue.edu) that partners undergraduate students and local community not-for-profit organizations to solve engineering-based problems in the community
Correlations in the properties of static and rapidly rotating compact stars
Correlations in the properties of the static compact stars (CSs) and the ones
rotating with the highest observed frequency of 1122Hz are studied using a
large set of equations of state (EOSs). These EOSs span various approaches and
their chemical composition vary from the nucleons to hyperons and quarks in
-equilibrium. It is found that the properties of static CS, like, the
maximum gravitational mass and radius corresponding to t he canonical mass and supramassive or
non-supramassive nature of the CS rotating at 1122 Hz are strongly correlated.
In particular, only those EOSs yield the CS rotating at 1122Hz to be
non-supramassive for which \left (\frac{M_{\rm max}^{\rm stat}}{M_\odot}\right
)^{1/2} \left (\frac{10{\rm km}}{R_{1.4}^{\rm stat}})^{3/2} is greater than
unity. Suitable parametric form which can be used to split the plane into the regions of different
supramassive nature of the CS rotating at 1122Hz is presented. Currently
measured maximum gravitational mass 1.76 of PSR J0437-4715 suggests
that the CS rotating at 1122Hz can be non-supramassive provided km.Comment: 13 pages, 4 figures, Appearing in Phys. Rev.
A Method for Dynamic Characterization and Response Prediction Using Ground Vibration Test(GVT)Data for Unknown Structures.
The Objective Of This Proposed Work Is To Develop A Reliable Method For Dynamic Characterization And Prediction Of Dynamic Response Of Structures Of Known/Unknown Configurations, By Processing The Free Vibration Data Generated Experimentally From The Ground Vibration Tests (GVT)Of The Prototype Vehicles. The Methodology Would Make Use Of The Measured Dynamic Data In Terms Of Mode Shapes, Natural Frequencies, Modal Damping, Point Impedances Etc.And Generate Modal (Scaled) Stiffness And Inertia Information That Will Be Used For Prediction Of Response Characteristics Of The Prototype Structure .
With These Objectives, The Present Work Develops The Mathematical Formulation Of The Method, And Demonstrates Its Reliability By Performing The Experiment On A Simple Cantilever Beam To Determine Its Dynamic Characteristics. Results On Scaled Modal Stiffness And Inertia, Generated Through The Method Using Experimental (GVT) Data Show Excellent Agreement With Those Generated By FE And Analytical Models .It Must Be Noted That A Valid Benchmarking Is Performed With The Condition That The Experimental Procedure Is 'Blind' To The Actual Stiffness And Inertia Distributions As Used In FEM Or Analytical Models . Agreement Of The Predicted Response Of The Structure With That From Direct Experiment And Those From The FE And Analytical Models Indicates That This Method Will Be A Promising Tool To Predict The Dynamic And Aeroelastic Characteristics Of Any Prototype Vehicle In The Future.
Once The Reliability Of The Method Is Established,It Can Be Extended To Determine The Dynamic And Aeroelastic Characteristics Of All Aircraft For Which Dynamic Characteristics Are Available From A Ground -; Vibration Test (GVT)
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