Design and assessment of a multiple sensor fault tolerant robust control system

This paper presents an enhanced robust control design structure to realise fault tolerance towards sensor faults suitable for multi-input-multi-output (MIMO) systems implementation. The proposed design permits fault detection and controller elements to be designed with considerations to stability and robustness towards uncertainties besides multiple faults environment on a common mathematical platform. This framework can also cater to systems requiring fast responses. A design example is illustrated with a fast, multivariable and unstable system, that is, the double inverted pendulum system. Results indicate the potential of this design framework to handle fast systems with multiple sensor faults

Practical design considerations for secondary air injection in wood-burning cookstoves: An experimental study

Billions of households worldwide cook using biomass fires and suffer from the toxic smoke emitted into their homes. Laboratory studies of wood-burning cookstoves demonstrate that secondary air injection can greatly reduce the emission of harmful air pollution, but these experimental advancements are not easily translated into practical cookstove designs that can be widely adopted. In this study, we use a modular cookstove platform to experimentally quantify the practical secondary air injection design requirements (e.g., flow rate, pressure, and temperature) to reduce mass emissions of particulate matter (PM), carbon monoxide (CO), and black carbon (BC) by at least 90% relative to a traditional cooking fire. Over the course of 111 experimental trials, we illuminate the physical mechanisms that drive emission reductions, and outline fundamental design principles to optimize cookstove performance. Using the experimental data, we demonstrate that low-cost (<$10) fans and blowers are available to drive the secondary flow, and can be independently powered using an inexpensive thermoelectric generator mounted nearby. Furthermore, size-resolved PM measurements show that secondary air injection inhibits particle growth, but the total number of particles generated remains relatively unaffected. We discuss the potential impacts for human health and investigate methods to mitigate the PM formation mechanisms that persist

The interferon-stimulated gene IFITM3 restricts West Nile virus infection and pathogenesis

The interferon-induced transmembrane protein (IFITM) family of proteins inhibit infection of several different enveloped viruses in cell culture by virtue of their ability to restrict entry and fusion from late endosomes. As few studies have evaluated the importance of Ifitm3 in vivo in restricting viral pathogenesis, we investigated its significance as an antiviral gene against West Nile virus (WNV), an encephalitic flavivirus, in cells and mice. Ifitm3(−/−) mice were more vulnerable to lethal WNV infection, and this was associated with greater virus accumulation in peripheral organs and central nervous system tissues. As no difference in viral burden in the brain or spinal cord was observed after direct intracranial inoculation, Ifitm3 likely functions as an antiviral protein in nonneuronal cells. Consistent with this, Ifitm3(−/−) fibroblasts but not dendritic cells resulted in higher yields of WNV in multistep growth analyses. Moreover, transcomplementation experiments showed that Ifitm3 inhibited WNV infection independently of Ifitm1, Ifitm2, Ifitm5, and Ifitm6. Beyond a direct effect on viral infection in cells, analysis of the immune response in WNV-infected Ifitm3(−/−) mice showed decreases in the total number of B cells, CD4(+) T cells, and antigen-specific CD8(+) T cells. Finally, bone marrow chimera experiments demonstrated that Ifitm3 functioned in both radioresistant and radiosensitive cells, as higher levels of WNV were observed in the brain only when Ifitm3 was absent from both compartments. Our analyses suggest that Ifitm3 restricts WNV pathogenesis likely through multiple mechanisms, including the direct control of infection in subsets of cells. IMPORTANCE As part of the mammalian host response to viral infections, hundreds of interferon-stimulated genes (ISGs) are induced. The inhibitory activity of individual ISGs varies depending on the specific cell type and viral pathogen. Among ISGs, the genes encoding interferon-induced transmembrane protein (IFITM) have been reported to inhibit multiple families of viruses in cell culture. However, few reports have evaluated the impact of IFITM genes on viral pathogenesis in vivo. In this study, we characterized the antiviral activity of Ifitm3 against West Nile virus (WNV), an encephalitic flavivirus, using mice with a targeted gene deletion of Ifitm3. Based on extensive virological and immunological analyses, we determined that Ifitm3 protects mice from WNV-induced mortality by restricting virus accumulation in peripheral organs and, subsequently, in central nervous system tissues. Our data suggest that Ifitm3 restricts WNV pathogenesis by multiple mechanisms and functions in part by controlling infection in different cell types

Low temperature properties of holographic condensates

In the current work we study various models of holographic superconductors at low temperature. Generically the zero temperature limit of those models are solitonic solution with a zero sized horizon. Here we generalized simple version of those zero temperature solutions to small but non-zero temperature T. We confine ourselves to cases where near horizon geometry is AdS^4. At a non-zero temperature a small horizon would form deep inside this AdS^4 which does not disturb the UV physics. The resulting geometry may be matched with the zero temperature solution at an intermediate length scale. We understand this matching from separation of scales by setting up a perturbative expansion in gauge potential. We have a better analytic control in abelian case and quantities may be expressed in terms of hypergeometric function. From this we calculate low temperature behavior of various quatities like entropy, charge density and specific heat etc. We also calculate various energy gaps associated with p-wave holographic superconductor to understand the underlying pairing mechanism. The result deviates significantly from the corresponding weak coupling BCS counterpart.Comment: 17 Page

Fermion correlators in non-abelian holographic superconductors

We consider fermion correlators in non-abelian holographic superconductors. The spectral function of the fermions exhibits several interesting features such as support in displaced Dirac cones and an asymmetric distribution of normal modes. These features are compared to similar ones observed in angle resolved photoemission experiments on high T_c superconductors. Along the way we elucidate some properties of p-wave superconductors in AdS_4 and discuss the construction of SO(4) superconductors.Comment: 49 pages, 11 figure

d+idd+id Holographic Superconductors

A holographic model of $d+id$ superconductors based on the action proposed by Benini, Herzog, and Yarom [arXiv:1006.0731] is studied. This model has a charged spin two field in an AdS black hole spacetime. Working in the probe limit, the normalizable solution of the spin two field in the bulk gives rise to a $d+id$ superconducting order parameter at the boundary of the AdS. We calculate the fermion spectral function in this\ superconducting background and confirm the existence of fermi arcs for non-vanishing Majorana couplings. By changing the relative strength $\gamma$ of the $d$ and $id$ condensations, the position and the size of the fermi arcs are changed. When $\gamma =1$, the spectrum becomes isotropic and the spectral function is s-wave like. By changing the fermion mass, the fermi momentum is changed. We also calculate the conductivity for these holographic $d+id$ superconductors where time reversal symmetry has been broken spontaneously. A non-vanishing Hall conductivity is obtained even without an external magnetic field.Comment: 24 pages,17 figures, Add more discussions on hall conductivity, two new figures, Matched with published versio

Innovative sponge-based moving bed-osmotic membrane bioreactor hybrid system using a new class of draw solution for municipal wastewater treatment

© 2016 Elsevier Ltd. For the first time, an innovative concept of combining sponge-based moving bed (SMB) and an osmotic membrane bioreactor (OsMBR), known as the SMB-OsMBR hybrid system, were investigated using Triton X-114 surfactant coupled with MgCl2 salt as the draw solution. Compared to traditional activated sludge OsMBR, the SMB-OsMBR system was able to remove more nutrients due to the thick-biofilm layer on sponge carriers. Subsequently less membrane fouling was observed during the wastewater treatment process. A water flux of 11.38 L/(m2 h) and a negligible reverse salt flux were documented when deionized water served as the feed solution and a mixture of 1.5 M MgCl2 and 1.5 mM Triton X-114 was used as the draw solution. The SMB-OsMBR hybrid system indicated that a stable water flux of 10.5 L/(m2 h) and low salt accumulation were achieved in a 90-day operation. Moreover, the nutrient removal efficiency of the proposed system was close to 100%, confirming the effectiveness of simultaneous nitrification and denitrification in the biofilm layer on sponge carriers. The overall performance of the SMB-OsMBR hybrid system using MgCl2 coupled with Triton X-114 as the draw solution demonstrates its potential application in wastewater treatment

Domain Wall Holography for Finite Temperature Scaling Solutions

We investigate a class of near-extremal solutions of Einstein-Maxwell-scalar theory with electric charge and power law scaling, dual to charged IR phases of relativistic field theories at low temperature. These are exact solutions of theories with domain wall vacua; hence, we use nonconformal holography to relate the bulk and boundary theories. We numerically construct a global interpolating solution between the IR charged solutions and the UV domain wall vacua for arbitrary physical choices of Lagrangian parameters. By passing to a conformal frame in which the domain wall metric becomes that of AdS, we uncover a generalized scale invariance of the IR scaling solution, indicating a connection to the physics of Lifshitz fixed points. Finally, guided by effective field theoretic principles and the physics of nonconformal D-branes, we argue for the applicability of domain wall holography even in theories with AdS critical points, namely those theories for which a scalar potential is dominated by a single exponential term over a large range

Awake chronic mouse model of targeted pial vessel occlusion via photothrombosis

Animal models of stroke are used extensively to study the mechanisms involved in the acute and chronic phases of recovery following stroke. A translatable animal model that closely mimics the mechanisms of a human stroke is essential in understanding recovery processes as well as developing therapies that improve functional outcomes. We describe a photothrombosis stroke model that is capable of targeting a single distal pial branch of the middle cerebral artery with minimal damage to the surrounding parenchyma in awake head-fixed mice. Mice are implanted with chronic cranial windows above one hemisphere of the brain that allow optical access to study recovery mechanisms for over a month following occlusion. Additionally, we study the effect of laser spot size used for occlusion and demonstrate that a spot size with small axial and lateral resolution has the advantage of minimizing unwanted photodamage while still monitoring macroscopic changes to cerebral blood flow during photothrombosis. We show that temporally guiding illumination using real-time feedback of blood flow dynamics also minimized unwanted photodamage to the vascular network. Finally, through quantifiable behavior deficits and chronic imaging we show that this model can be used to study recovery mechanisms or the effects of therapeutics longitudinally.R01 EB021018 - NIBIB NIH HHS; R01 MH111359 - NIMH NIH HHS; R01 NS108472 - NINDS NIH HHSPublished versio

Holographic Superconductors from Einstein-Maxwell-Dilaton Gravity

We construct holographic superconductors from Einstein-Maxwell-dilaton gravity in 3+1 dimensions with two adjustable couplings $\alpha$ and the charge $q$ carried by the scalar field. For the values of $\alpha$ and $q$ we consider, there is always a critical temperature at which a second order phase transition occurs between a hairy black hole and the AdS RN black hole in the canonical ensemble, which can be identified with the superconducting phase transition of the dual field theory. We calculate the electric conductivity of the dual superconductor and find that for the values of $\alpha$ and $q$ where $\alpha/q$ is small the dual superconductor has similar properties to the minimal model, while for the values of $\alpha$ and $q$ where $\alpha/q$ is large enough, the electric conductivity of the dual superconductor exhibits novel properties at low frequencies where it shows a "Drude Peak" in the real part of the conductivity.Comment: 25 pages, 13 figures; v2, typos corrected; v3, refs added, to appear in JHE