Directed chaos in a billiard chain with transversal magnetic field

In generic Hamiltonian systems with a mixed phase space chaotic transport may be directed and ballistic rather than diffusive. We investigate one particular model showing this behaviour, namely a spatially periodic billiard chain in which electrons move under the influence of a perpendicular magnetic field. We analyze the phase-space structure and derive an explicit expression for the chaotic transport velocity. Unlike previous studies of directed chaos our model has a parameter regime in which the dispersion of an ensemble of chaotic trajectories around its moving center of mass is essentially diffusive. We explain how in this limit the deterministic chaos reduces to a biased random walk in a billiard with a rough surface. The diffusion constant for this simplified model is calculated analytically

Signature of directed chaos in the conductance of a nanowire

We study the conductance of chaotic or disordered wires in a situation where equilibrium transport decomposes into biased diffusion and a counter-moving regular current. A possible realization is a semiconductor nanostructure with transversal magnetic field and suitably patterned surfaces. We find a non-trivial dependence of the conductance on the wire length which differs qualitatively from Ohm's law by the existence of a characteristic length scale and a finite saturation value

Designing a Pipeline for Predicting Power Grid Stability with Artificial Neural Network (ANN)

Renewable energy sources are becoming more popular, providing a much-needed alternative to traditional, limited, and climate-unfriendly energy sources. Wireless sensors, cloud computing, cyber security, and wide-area monitoring are basic communication and control technologies for smart grid applications. Design of communication and control architectures for the adoption of smart energy grids for rural loads and distributed energy, including energy storage solutions. In this work, a Machine Learning module called scikit-learn is used for pre-processing of labeled input data by using StandardScaler, KFold for cross-validation, and Confusion matrix for measuring performance. Also, the ML technique uses the binary classification method to divide the ‘stabf’ data into two parts as stable and unstable. Here deep learning-based Artificial Neural Network (ANN) has been used to evaluate the result and to predict new grid data to enhance stability. ANN takes 12 input nodes in the input layer and three hidden layers out of which two hidden layer takes 24 nodes and another one takes 12 nodes and an output layer consisting of a single node. Adam optimizer has been used for model compilation and loss function calculation ‘binary_crossentropy’ is used. Finally, after successful completion of the evaluation process, this model gives a test accuracy result of 98.33%

Use of waste polyethylene in bituminous concrete mixes

Bituminous Concrete (BC) is a composite material mostly used in construction projects like road surfacing, airports, parking lots etc. It consists of asphalt or bitumen (used as a binder) and mineral aggregate which are mixed together & laid down in layers then compacted. Now a days, the steady increment in high traffic intensity in terms of commercial vehicles, and the significant variation in daily and seasonal temperature put us in a demanding situation to think of some alternatives for the improvisation of the pavement characteristics and quality by applying some necessary modifications which shall satisfy both the strength as well as economical aspects. Also considering the environmental approach, due to excessive use of polythenes in day to day business, the pollution to the environment is enormous. Since the polythenes are not biodegradable, the need of the current hour is to use the waste polythene in some beneficial purposes. This paper presents a research conducted to study the behavior of BC mix modified with waste polythene. Various percentages of polythene are used for preparation of mixes with a selected aggregate grading as given in the IRC Code. The role of polythene in the mix is studied for various engineering properties by preparing Marshall samples of BC mixtures with and without polymer. Marshall properties such as stability, flow value, unit weight, air voids are used to determine optimum polythene content for the given grade of bitumen (80/100)

Biodiesel: Freedom from Dependence on Fossil Fuels?

In view of the depleting oil reserves and exponential rise in petroleum prices, the search for alternative sources of fuel is very timely and important. The present paper addresses the underlying issues in biodiesel production from biomaterials and sustainable production and supply of first-generation biofuels, especially the one from jatropha. The agencies and research institutions involved in the production of biofuels and the national and international efforts made in this regard are discussed here. There is also a dire need of a step towards large-scale production and supply of second-generation biofuels, although in infant stage, to strengthen the world economy in general and Indian economy in particular. However, the production of biofuels are likely to have serious socio-economic implications especially to the lesser developed societies. This needs serious attention from policy makers and public at large

Dynamic response of pile foundations under coupled vibration

For the dynamic response of pile foundation under coupled vibration single piles and 2 x 2 group piles with length to diameter ratios 10,15 and 20 have taken. For group piles, spacing to diameter ratios of 2, 3 and 4 for each length to diameter ratio were used. Formulation of the theory of plane strain model of Novak (Novak, 1974) for horizontal and rocking vibrations to predict the dynamic response of single pile and pile group. Static interaction factors (El-Sharnouby and Novak, 1986) were determined to account pile-soil-pile interaction. By using Novak’s plane strain model with static interaction factor approach the frequency independent dynamic response of both single pile and group of pile for horizontal vibration and rocking were determined. Finally the predicted response of single and group piles were compared with the observed response reported in Manna (2009

Stochastic boundary conditions for molecular dynamics simulations

In this paper we develop a stochastic boundary conditions (SBC) for event-driven molecular dynamics simulations of a finite volume embedded within an infinite environment. In this method, we first collect the statistics of injection/ejection events in periodic boundary conditions (PBC). Once sufficient statistics are collected, we remove the PBC and turn on the SBC. In the SBC simulations, we allow particles leaving the system to be truly ejected from the simulation, and randomly inject particles at the boundaries by resampling from the injection/ejection statistics collected from the current or previous simulations. With the SBC, we can measure thermodynamic quantities within the grand canonical ensemble, based on the particle number and energy fluctuations. To demonstrate how useful the SBC algorithm is, we simulated a hard disk gas and measured the pair distribution function, the compressibility and the specific heat, comparing them against literature values.Comment: 24 pages, 16 figure

Complexity results for the Pilot Assignment problem in Cell-Free Massive MIMO

Wireless communication is enabling billions of people to connect to each other and the internet, transforming every sector of the economy, and building the foundations for powerful new technologies that hold great promise to improve lives at an unprecedented rate and scale. The rapid increase in the number of devices and the associated demands for higher data rates and broader network coverage fuels the need for more robust wireless technologies. The key technology identified to address this problem is referred to as Cell-Free Massive MIMO (CF-mMIMO). CF-mMIMO is accompanied by many challenges, one of which is efficiently allocating limited resources. In this paper, we focus on a major resource allocation problem in wireless networks, namely the Pilot Assignment problem (PA). We show that PA is strongly NP-hard and that it does not admit a polynomial-time constant-factor approximation algorithm. Further, we show that PA cannot be approximated in polynomial time within $\mathcal{O}(K^2)$ (where $K$ is the number of users) when the system consists of at least three pilots. Finally, we present an approximation lower bound of $1.058$ (resp. $\epsilon|K|^2$, for $\epsilon >0$) in special cases where the system consists of exactly two (resp. three) pilots.Comment: 20 pages, 0 figure