11,543 research outputs found
Throughput Scaling Laws for Wireless Networks with Fading Channels
A network of n communication links, operating over a shared wireless channel,
is considered. Fading is assumed to be the dominant factor affecting the
strength of the channels between transmitter and receiver terminals. It is
assumed that each link can be active and transmit with a constant power P or
remain silent. The objective is to maximize the throughput over the selection
of active links. By deriving an upper bound and a lower bound, it is shown that
in the case of Rayleigh fading (i) the maximum throughput scales like
(ii) the maximum throughput is achievable in a distributed fashion. The upper
bound is obtained using probabilistic methods, where the key point is to upper
bound the throughput of any random set of active links by a chi-squared random
variable. To obtain the lower bound, a decentralized link activation strategy
is proposed and analyzed.Comment: Submitted to IEEE Transactions on Information Theory (Revised
Self-Gravitational Corrections to the Cardy-Verlinde Formula and the FRW Brane Cosmology in SdS_5 Bulk
The semiclassical corrections to the Cardy-Verlinde entropy of a
five-dimensional Schwarzschild de-Sitter black hole (SdS_5) are explicitly
evaluated. These corrections are considered within the context of KKW analysis
and arise as a result of the self-gravitation effect. In addition, a
four-dimensional spacelike brane is considered as the boundary of the SdS_5
bulk background. It is already known that the induced geometry of the brane is
exactly given by that of a radiation-dominated FRW universe. By exploiting the
CFT/FRW-cosmology relation, we derive the self-gravitational corrections to the
first Friedmann-like equation which is the equation of the brane motion. The
additional term that arises due to the semiclassical analysis can be viewed as
stiff matter where the self-gravitational corrections act as the source for it.
This result is contrary to standard analysis that regards the charge of SdS_5
bulk black hole as the source for stiff matter. Furthermore, we rewrite the
Friedmann-like equation in a such way that it represents the conservation
equation of energy of a point particle moving in a one-dimensional effective
potential. The self-gravitational corrections to the effective potential and,
consequently, to the point particle's motion are obtained. A short analysis on
the asymptotic behavior of the 4-dimensional brane is presented.Comment: 16 pages, LaTeX; (v2) references added and correcte
An IOT based Solar Integrated Home Security System by using GSM Module and Raspberry pi
At present the world advancement depends on its technology. IoT (Internet of Things) is the latest technology which connects the devices over a network using cloud computing and web applications to for efficient operation. Home security systems comprise a GSM module and Raspberry Pi with relay which is door security sensors. These systems can response rapidly when burglar intrudes in a home, office etc. And alerts the respective holder. Suspected activities are conveyed to user through SMS or CALL or SNAP SHOT of the burglar to the mobile by using GSM technology the total system is operated a single credit card sized computer that is Raspberry Pi
HEER: Hybrid Energy Efficient Reactive Protocol for Wireless Sensor Networks
Wireless Sensor Networks (WSNs) consist of numerous sensors which send sensed
data to base station. Energy conservation is an important issue for sensor
nodes as they have limited power.Many routing protocols have been proposed
earlier for energy efficiency of both homogeneous and heterogeneous
environments. We can prolong our stability and network lifetime by reducing our
energy consumption. In this research paper, we propose a protocol designed for
the characteristics of a reactive homogeneous WSNs, HEER (Hybrid Energy
Efficient Reactive) protocol. In HEER, Cluster Head(CH) selection is based on
the ratio of residual energy of node and average energy of network. Moreover,
to conserve more energy, we introduce Hard Threshold (HT) and Soft Threshold
(ST). Finally, simulations show that our protocol has not only prolonged the
network lifetime but also significantly increased stability period.Comment: 2nd IEEE Saudi International Electronics, Communications and
Photonics Conference (SIECPC 13), 2013, Riyadh, Saudi Arabi
Do Life Style Factors And Socioeconomic Variables Explain Why Black Women Have A Remarkably Higher Body Mass Index (BMI) Than White Women In The United States? Findings From The 2010 National Health Interview Survey
Objective: There are marked inequalities in body mass index (BMI), overweight, and obesity across ethnic groups. We sought to examine the extent to which lifestyle factors and socioeconomic variables explain the higher BMI in Black women compared to White women in the United States.
Methods: We used data from the 2010 National Health Interview Survey (NHIS) and limited the sample to non-Hispanic Black and non-Hispanic White women (n = 9,491). We employed normal regression and compared the association of race with BMI before and after adjusting for lifestyle factors (diet, physical activity, smoking, and drinking) and socioeconomic variables (education, ratio of income to poverty threshold, occupation, and home ownership). Data analysis was performed in 2012.
Results: The difference between the BMI of Black and White women decreased from 2.91 to 2.17 Kg/m2 (i.e. a decrease of 27.2%) after adjusting for lifestyle factors and socioeconomic variables. Multivariate results also showed that higher consumption of fruit/vegetables and beans, lower consumption of red meat and sugar sweetened beverages, physical activity, smoking, regular drinking, and higher socioeconomic status were associated with lower BMI.
Conclusions: Lifestyle factors and socioeconomic variables explain about a quarter of the BMI inequality between Black and White women. Thus, interventions that promote healthy eating and physical activity among Blacks as well as social policies that ameliorate socioeconomic inequalities between races might be able to reduce the current BMI inequality between Black and White women
Rethinking interpretation: Input-agnostic saliency mapping of deep visual classifiers
Saliency methods provide post-hoc model interpretation by attributing input
features to the model outputs. Current methods mainly achieve this using a
single input sample, thereby failing to answer input-independent inquiries
about the model. We also show that input-specific saliency mapping is
intrinsically susceptible to misleading feature attribution. Current attempts
to use 'general' input features for model interpretation assume access to a
dataset containing those features, which biases the interpretation. Addressing
the gap, we introduce a new perspective of input-agnostic saliency mapping that
computationally estimates the high-level features attributed by the model to
its outputs. These features are geometrically correlated, and are computed by
accumulating model's gradient information with respect to an unrestricted data
distribution. To compute these features, we nudge independent data points over
the model loss surface towards the local minima associated by a
human-understandable concept, e.g., class label for classifiers. With a
systematic projection, scaling and refinement process, this information is
transformed into an interpretable visualization without compromising its
model-fidelity. The visualization serves as a stand-alone qualitative
interpretation. With an extensive evaluation, we not only demonstrate
successful visualizations for a variety of concepts for large-scale models, but
also showcase an interesting utility of this new form of saliency mapping by
identifying backdoor signatures in compromised classifiers.Comment: Accepted for publication in AAAI 202
Artificial leaf device for hydrogen generation from immobilised C. reinhardtii microalgae
We developed a fully biomimetic leaf-like device for hydrogen production which allows incorporated fabric-immobilised microalgae culture to be simultaneously hydrated with media and harvested from the produced hydrogen in a continuous flow regime without the need to replace the algal culture. Our leaf device produces hydrogen by direct photolysis of water resulting from redirecting the photosynthetic pathways in immobilised microalgae due to the lack of oxygen. In contrast to the many other reports in the literature on batch photobioreactors producing hydrogen from suspension culture of microalgae, we present the first report where this is done in a continuous manner from a fabric-immobilised microalgae culture. The reported artificial leaf device maximises the sunlight energy utilisation per gram of algae and can be upscaled cheaply and easily to cover large areas. We compared the production of hydrogen from both immobilised and suspended cultures of C. reinhardtii microalgae under sulphur, phosphorus and oxygen deprived conditions. The viability and potential of this approach is clearly demonstrated. Even though this is a first prototype, the hydrogen yield of our artificial leaf device is twenty times higher per gram of algae than in previously the reported batch reactors. Such leaf-like devices could potentially be made from flexible plastic sheets and installed on roofs and other sun-exposed surfaces that are inaccessible by photovoltaic cells. The ability to continuously produce inexpensive hydrogen by positioning inexpensive sheets onto any surface could have an enormous importance in the field of biofuels. The proposed new concept can provide a cleaner and very inexpensive way of bio-hydrogen generation by flexible sheet-like devices
Performance analysis of d-dimensional quantum cryptography under state-dependent diffraction
Standard protocols for quantum key distribution (QKD) require that the sender
be able to transmit in two or more mutually unbiased bases. Here, we analyze
the extent to which the performance of QKD is degraded by diffraction effects
that become relevant for long propagation distances and limited sizes of
apertures. In such a scenario, different states experience different amounts of
diffraction, leading to state-dependent loss and phase acquisition, causing an
increased error rate and security loophole at the receiver. To solve this
problem, we propose a pre-compensation protocol based on pre-shaping the
transverse structure of quantum states. We demonstrate, both theoretically and
experimentally, that when performing QKD over a link with known,
symbol-dependent loss and phase shift, the performance of QKD will be better if
we intentionally increase the loss of certain symbols to make the loss and
phase shift of all states same. Our results show that the pre-compensated
protocol can significantly reduce the error rate induced by state-dependent
diffraction and thereby improve the secure key rate of QKD systems without
sacrificing the security.Comment: 10 pages, 6 figure
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