426 research outputs found
Probabilistic analysis of security attacks in cloud environment using hidden Markov models
© 2020 John Wiley & Sons, Ltd. The rapidly growing cloud computing paradigm provides a cost-effective platform for storing, sharing, and delivering data and computation through internet connectivity. However, one of the biggest barriers for massive cloud adoption is the growing cybersecurity threats/risks that influence its confidence and feasibility. Existing threat models for clouds may not be able to capture complex attacks. For example, an attacker may combine multiple security vulnerabilities into an intelligent, persistent, and sequence of attack behaviors that will continuously act to compromise the target on clouds. Hence, new models for detection of complex and diversified network attacks are needed. In this article, we introduce an effective threat modeling approach that has the ability to predict and detect the probability of occurrence of various security threats and attacks within the cloud environment using hidden Markov models (HMMs). The HMM is a powerful statistical analysis technique and is used to create a probability matrix based on the sensitivity of the data and possible system components that can be attacked. In addition, the HMM is used to provide supplemental information to discover a trend attack pattern from the implicit (or hidden) raw data. The proposed model is trained to identify anomalous sequences or threats so that accurate and up-to-date information on risk exposure of cloud-hosted services are properly detected. The proposed model would act as an underlying framework and a guiding tool for cloud systems security experts and administrators to secure processes and services over the cloud. The performance evaluation shows the effectiveness of the proposed approach to find attack probability and the number of correctly detected attacks in the presence of multiple attack scenarios
An efficient design of 45-nm CMOS low-noise charge sensitive amplifier for wireless receivers
Amplifiers are widely used in signal receiving circuits, such as antennas, medical imaging, wireless devices and many other applications. However, one of the most challenging problems when building an amplifier circuit is the noise, since it affects the quality of the intended received signal in most wireless applications. Therefore, a preamplifier is usually placed close to the main sensor to reduce the effects of interferences and to amplify the received signal without degrading the signal-to-noise ratio. Although different designs have been optimized and tested in the literature, all of them are using larger than 100 nm technologies which have led to a modest performance in terms of equivalent noise charge (ENC), gain, power consumption, and response time. In contrast, we consider in this paper a new amplifier design technology trend and move towards sub 100 nm to enhance its performance. In this work, we use a pre-well-known design of a preamplifier circuit and rebuild it using 45 nm CMOS technology, which is made for the first time in such circuits. Performance evaluation shows that our proposed scaling technology, compared with other scaling technology, extremely reduces ENC of the circuit by more than 95%. The noise spectral density and time resolution are also reduced by 25% and 95% respectively. In addition, power consumption is decreased due to the reduced channel length by 90%. As a result, all of those enhancements make our proposed circuit more suitable for medical and wireless devices
Monopolar and dipolar relaxation in spin ice HoTiO
When degenerate states are separated by large energy barriers, the approach
to thermal equilibrium can be slow enough that physical properties are defined
by the thermalization process rather than the equilibrium. The exploration of
thermalization pushes experimental boundaries and provides refreshing insights
into atomic scale correlations and processes that impact steady state dynamics
and prospects for realizing solid state quantum entanglement. We present a
comprehensive study of magnetic relaxation in HoTiO based on
frequency-dependent susceptibility measurements and neutron diffraction studies
of the real-time atomic-scale response to field quenches. Covering nearly ten
decades in time scales, these experiments uncover two distinct relaxation
processes that dominate in different temperature regimes. At low temperatures
(0.6K<T<1K) magnetic relaxation is associated with monopole motion along the
applied field direction through the spin-ice vacuum. The increase of the
relaxation time upon cooling indicates reduced monopole conductivity driven by
decreasing monopole concentration and mobility as in a semiconductor. At higher
temperatures (1K<T<2K) magnetic relaxation is associated with the reorientation
of monopolar bound states as the system approaches the single-spin tunneling
regime. Spin fractionalization is thus directly exposed in the relaxation
dynamics
A Secure Cluster-Based Multipath Routing Protocol for WMSNs
The new characteristics of Wireless Multimedia Sensor Network (WMSN) and its design issues brought by handling different traffic classes of multimedia content (video streams, audio, and still images) as well as scalar data over the network, make the proposed routing protocols for typical WSNs not directly applicable for WMSNs. Handling real-time multimedia data requires both energy efficiency and QoS assurance in order to ensure efficient utility of different capabilities of sensor resources and correct delivery of collected information. In this paper, we propose a Secure Cluster-based Multipath Routing protocol for WMSNs, SCMR, to satisfy the requirements of delivering different data types and support high data rate multimedia traffic. SCMR exploits the hierarchical structure of powerful cluster heads and the optimized multiple paths to support timeliness and reliable high data rate multimedia communication with minimum energy dissipation. Also, we present a light-weight distributed security mechanism of key management in order to secure the communication between sensor nodes and protect the network against different types of attacks. Performance evaluation from simulation results demonstrates a significant performance improvement comparing with existing protocols (which do not even provide any kind of security feature) in terms of average end-to-end delay, network throughput, packet delivery ratio, and energy consumption
A Lightweight and Efficient Digital Image Encryption Using Hybrid Chaotic Systems for Wireless Network Applications
Due to limited processing capabilities and other constraints of most wireless networks, many existing security algorithms do not consider the network efficiency. This is because most of these security solutions exhibit intolerable overhead and consider only securing scalar data, which are not suitable for other data types such as digital images, hence affecting the provided security level and network performance. Thus, in this paper, we propose a lightweight and efficient security scheme based on chaotic algorithms to efficiently encrypt digital images. Our proposed algorithm handles digital images in two phases: Firstly, digital images are split into blocks and compressed by processing them in frequency domain instead of Red-Green-Blue (RGB) domain. The ultimate goal is to reduce their sizes to speed up the encryption process and to break the correlation among image pixel values. Secondly, 2D Logistic chaotic map is deployed in key generation, permutation, and substitution stages for image pixel shuffling and transposition. In addition, 2D Henon chaotic map is deployed to change the pixel values in the diffusion stage in order to enhance the required level of security and resist various security attacks. Security performance analysis based on standard test images shows that our proposed scheme overcomes the performance of other existing techniques
Quantum Criticality without Tuning in the Mixed Valence Compound beta-YbAlB4
Fermi liquid theory, the standard theory of metals, has been challenged by a
number of observations of anomalous metallic behavior found in the vicinity of
a quantum phase transition. The breakdown of the Fermi liquid is accomplished
by fine-tuning the material to a quantum critical point using a control
parameter such as the magnetic field, pressure, or chemical composition. Our
high precision magnetization measurements of the ultrapure f-electron based
superconductor {\beta}-YbAlB4 demonstrate a scaling of its free energy
indicative of zero-field quantum criticality without tuning in a metal. The
breakdown of Fermi-liquid behavior takes place in a mixed-valence state, in
sharp contrast with other known examples of quantum critical f-electron systems
that are magnetic Kondo lattice systems with integral valence.Comment: 26 pages, 7 figures including supporting online matelial
Antihypertensive, antidyslipidemic and endothelial modulating activities of Orchis mascula
The objective of this study was to investigate the possible mode(s) of action for the medicinal use of Orchis mascula (OM) (family Orchidaceae) in hypertension and dyslipidemia. In spontaneously hypertensive rats (SHRs), OM significantly (
Ring-Exchange Interaction Effects on Magnons in Dirac Magnet CoTiO
In magnetically ordered materials with localized electrons, the fundamental
magnetic interactions are due to exchange of electrons [1-3]. Typically, only
the interaction between pairs of electrons' spins is considered to explain the
nature of the ground state and its excitations, whereas three-, four-, and
six-spin interactions are ignored. When these higher order processes occur in a
loop they are called cyclic or ring exchange. The ring-exchange interaction is
required to explain low temperature behavior in bulk and thin films of solid
He [4-8]. It also plays a crucial role in the quantum magnet LaCuO
[9,10]. Here, we use a combination of time domain THz (TDTS) and magneto-Raman
spectroscopies to measure the low energy magnetic excitations in CoTiO, a
proposed Dirac topological magnon material [11,12] where the origin of the
energy gap in the magnon spectrum at the Brillouin zone center remains unclear.
We measured the magnetic field dependence of the energies of the two lowest
energy magnons and determine that the gap opens due to the ring-exchange
interaction between the six spins in a hexagon. This interaction also explains
the selection rules of the THz magnon absorption. Finally, we clarify that
topological surface magnons are not expected in CoTiO. Our study
demonstrates the power of combining TDTS and Raman spectroscopies with theory
to identify the microscopic origins of the magnetic excitations in quantum
magnets.Comment: 7 pages, 4 figures in main text, 26 pages and 11 figures in
supplemen
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