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Editorial: Simulating Normal and Arrhythmic Dynamics: From Sub-cellular to Tissue and Organ Level
No full textPotential of Early Direct Injection (EDI) for simultaneous NOx and soot emission reduction in a heavy duty turbocharged diesel engine
No full textEarly Direct Injection (EDI) in diesel engines with multiple injections has the potential to simultaneously reduce Nitrogen Oxide (NOx) and soot. The current work involved carrying out three-dimensional Computational Fluid Dynamic (CFD) simulations and engine experiments in order to evaluate EDI strategies on a heavy-duty diesel-fuelled engine operating at 25% load with the motivation to operate in Homogeneous Charge Compression Ignition (HCCI) mode. A uniformity Index (UI) parameter was defined to assess charge homogeneity. Results showed significant in-homogeneity and presence of wall-film for EDI. Simulations were conducted to assess improvement of charge homogeneity by several strategies; narrow spray included angle, injection timing, multiple injections and intake air heating. The maximum UI achieved by EDI was 0.78. Further work involved engine experimentation to assess the EDI strategy with dual injection. The first injection timing was varied from 90 degrees to 20 degrees Before Top Dead Center (BTDC) with cooled Exhaust Gas Recirculation (EGR) rate of 20%. The effect of EGR rate (0 to 35%) on the combustion behaviour was studied. An Optimized EDI (OptimEDI) strategy was developed which consisted of triple injections with fuel mass split ratio of 41%-45%-14% and an early first injection. This strategy gave 20% NOx and soot reduction simultaneously over the conventional Compression Ignition (CI) mode
Optimising graphene visibility in van der Waals heterostructures
No full textGraphene constitutes one of the key elements in many functional van der Waals heterostructures. However, it has negligible optical visibility due to its monolayer nature. Here we study the visibility of graphene in various van der Waals heterostructures and include the effects of the source spectrum, oblique incidence and the spectral sensitivity of the detector to obtain a realistic model. A visibility experiment is performed at different wavelengths, resulting in a very good agreement with our calculations. This allows us to reliably predict the conditions for better visibility of graphene in van der Waals heterostructures. The framework and the codes provided in this work can be extended to study the visibility of any 2D material within an arbitrary van der Waals heterostructure
SMOOTH POINTS IN OPERATOR SPACES AND SOME BISHOP-PHELPS-BOLLOBAS TYPE THEOREMS IN BANACH SPACES
No full textWe introduce the notion of approximate norm attainment set of a bounded linear operator between Banach spaces and use it to obtain a complete characterization of smooth points in the space of compact linear operators, provided the domain space is reflexive and Kadets-Klee. We also apply the concept to characterize strong BPB property (sBPBp) of a pair of Banach spaces. We further introduce uniform epsilon-BPB approximation of a bounded linear operator and uniform strong BPB property (uniform sBPBp) with respect to a given family of norm one linear operators and explore some of the relevant properties to illustrate its connection with earlier studies on Bishop-Phelps-Bollobas type theorems in Banach spaces. It is evident that our study has deep connections with the study of smooth points in operator spaces. We obtain a complete characterization of uniform sBPBp for a pair of Banach spaces, with respect to a given family of norm one bounded linear operators between them. As the final result of this paper, we prove that if X is a reflexive Kadets-Klee Banach space and Y is any Banach space, then the pair (X, Y) has sBPBp for compact operators. Our results extend, complement and improve some of the earlier results in this context
Photo and thermal induced Bi2Se3 formation from Bi/GeSe2 hetero junction layer for topological insulator
No full textIn the present paper, we report the evolution of Bi2Se3 topological phase from the Bi diffusion into GeSe(2 )layer in the Bi/GeSe(2 )hetero junction film with light and thermal energy. The photo and thermal induced changes in the structural and optical properties of thermally evaporated Bi/GeSe2 bilayer film has been studied by various characterization techniques. The amorphous to crystalline phase transition and the formation of Bi2Se3 topological phase was confirmed from the X-ray diffraction analysis. The deposition as well as diffusion of Bi into GeSe2 layer changed the optical constants like transmitivity, absorption power, optical band gap, Urbach energy, Tauc parameter as studied from UV-Vis-NIR spectroscopy. The transmission power decreased after thermal annealing and laser irradiation where the reverse effect was found in case of absorption coefficient. The optical band gap decreased after diffusion which can be explained on the basis of density of defect states with an increase in disorder. Scanning electron microscopy investigations showed that the surface morphology was influenced by the diffusion phenomena. The Raman analysis also confirms the Bi(2)Se(3 )phase evolution with appropriate vibrational peaks. The modifications in optical parameters with thermal and light induced diffusion can be used in various optical applications using such metal/chalcogenides heterojunction layers
Analytical Estimation of Turn ON Switching Loss of SiC MOSFET and Schottky Diode Pair From Datasheet Parameters
No full textEstimation of switching loss at the early stages of design is essential for determination of switching frequency and selection of power devices. Analytical estimation similar to gate charge method results in fastest and easiest computation when compared with simulation or double pulse test based experimental approach. This paper presents an analytical estimation method of turn ON switching loss of a SiC MOSFET and SiC Schottky barrier diode (SBD) pair from datasheet parameters and using values of common source and dc bus inductances. Turn ON losses are considered as they dominate the total switching loss. The presented method models the quadratic nature of the transfer characteristics and results in better estimation of current rise time when compared with the linear approximation used in the literature. During voltage fall, the non-linear nature of the parasitic capacitances of both the switch and the diode are considered. The simulation and experimental results confirm the accuracy of the presented method over a range of operating conditions for two 1.2-kV discrete SiC MOSFET and SBD pairs of different current ratings
AutoBoT: Resilient and Cost-Effective Scheduling of a Bag of Tasks on Spot VMs
No full textMany data and task parallel applications can be modeled as a Bag of Tasks (BoT), and scheduled on distributed systems such as Grids, Clusters, and Clouds. We propose AutoBoT, a collection of scheduling strategies for BoTs with hard deadlines on Cloud Virtual Machines (VMs), to lower the overall monetary cost-a distinctive factor for Clouds. Besides reliable fixed-price VMs, AutoBoT uniquely reduces costs by including preemptible spot-priced VMs that are much cheaper, but are unreliable and have time-variant pricing. It guarantees timely completion by making active runtime decisions on pricing, number of VMs to acquire/release, and on task placement, checkpointing and migration. Our rigorous simulations of 7 Million BoT runs sampled from the Google cluster workload uses a realistic Cloud model and 6 months of Amazon EC2 pricing data to compare AutoBoT against two baseline algorithms. We analyze the impact of BoT size, data centers, time periods, deadline duration, loss budget and checkpointing strategies. AutoBoT often gives approximate to 80% profit and rare but bounded losses, compared to using only fixed-price VMs. Further, its 100 percent completion guarantee is 23-42 percent better than using only spot-priced VMs which offer a similar profit
Combined measurements of Higgs boson couplings in proton- proton collisions at v s=13TeV
No full textCombined measurements of the production and decay rates of the Higgs boson, as well as its couplings to vector bosons and fermions, are presented. The analysis uses the LHC proton-proton collision data set recorded with the CMS detector in 2016 at fb-1. The combination is based on analyses targeting the five main Higgs boson production mechanisms (gluon fusion, vector boson fusion, and associated production with a W or Z boson, or a top quark-antiquark pair) and the following decay modes: H, ZZ, WW, , bb, and . Searches for invisible Higgs boson decays are also considered. The best-fit ratio of the signal yield to the standard model expectation is measured to be =1.17 +/- 0.10, assuming a Higgs boson mass of 125.09. Additional results are given for various assumptions on the scaling behavior of the production and decay modes, including generic parametrizations based on ratios of cross sections and branching fractions or couplings. The results are compatible with the standard model predictions in all parametrizations considered. In addition, constraints are placed on various two Higgs doublet models
High-Q On-Chip C-Band Inductor With a Nanocrystalline MnZn-Ferrite Film Core
No full textThe miniaturized on-chip inductor was developed for the C-band (4-8 GHz) and beyond, to meet the requirements of upcoming 5G technology devices. This paper presents the deposition of nanocrystalline manganese-zinc ferrite (MnxZn1-xFe2O4; x = 0.5) thin films in a CMOS-compatible way on top of an on-chip inductor structure. A 200 nm-thick film was conformally deposited directly on a foundry-fabricated inductor after removing the top passivation layer by dry etching. The Q-factor is found to be enhanced by 10% at the upper end (8 GHz) of the C-band, while the self-resonance frequency of the inductor is up-shifted to 21 from 16 GHz. The film on a dummy Si (100) substrate exhibits saturation magnetization (4 pi M-S = 160 mT) and coercivity (H-C = 3.5 mT) much lower than for the bulk material. The film was deposited by a rapid (<5 min) and low-temperature (<200 degrees C) solution-based process under microwave irradiation (2.45 GHz) of 300 W. This is the first report of an on-chip C-band inductor with a manganese-zinc ferrite film core
HyPar: A divide-and-conquer model for hybrid CPU-GPU graph processing
No full textEfficient processing of graph applications on heterogeneous CPU-GPU systems require effectively harnessing the combined power of both the CPU and GPU devices. This paper presents HyPar, a divide-and-conquer model for processing graph applications on hybrid CPU-GPU systems. Our strategy partitions the given graph across the devices and performs simultaneous independent computations on both the devices. The model provides a simple and generic API, supported with efficient runtime strategies for hybrid executions. The divide-and-conquer model is demonstrated with five graph applications and using experiments with these applications on a heterogeneous system it is shown that our HyPar strategy provides equivalent performance to the state-of-art, optimized CPU-only and GPU-only implementations of the corresponding applications. When compared to the prevalent BSP approach for multi-device executions of graphs, our HyPar method yields 74%-92% average performance improvements