A novel integrated modeling approach for filter diagnosis in gas turbine air intake system

Due to the complex and harsh environmental factors, the useful life of the filter in the gas turbine air intake system is usually less than its design life. When the filter is seriously degraded, the power and thermal efficiency of the gas turbine will decrease obviously due to the increase of inlet pressure loss. For evaluating the health condition of filters in the air intake system, this work forms a filter pressure loss model with the defined health index for the filter and five external environmental and control factors. By integrating the gas path component model, the combined model is applied in a real data set and the results show that (i) the proposed health index is efficient in representing the degradation state of the filter, (ii) the influencing factors on the pressure loss are successfully decoupled and their contributions on the pressure are quantitatively estimated, and (iii) the integrated model of filter pressure loss and gas path component can be used to better estimate the deterioration states of the filter as well as the gas turbine performance.

Connected Fundamental Groups and Homotopy Contacts in Fibered Topological (C, R) Space

The algebraic as well as geometric topological constructions of manifold embeddings and homotopy offer interesting insights about spaces and symmetry. This paper proposes the construction of 2-quasinormed variants of locally dense p-normed 2-spheres within a non-uniformly scalable quasinormed topological (C, R) space. The fibered space is dense and the 2-spheres are equivalent to the category of 3-dimensional manifolds or three-manifolds with simply connected boundary surfaces. However, the disjoint and proper embeddings of covering three-manifolds within the convex subspaces generates separations of p-normed 2-spheres. The 2-quasinormed variants of p-normed 2-spheres are compact and path-connected varieties within the dense space. The path-connection is further extended by introducing the concept of bi-connectedness, preserving Urysohn separation of closed subspaces. The local fundamental groups are constructed from the discrete variety of path-homotopies, which are interior to the respective 2-spheres. The simple connected boundaries of p-normed 2-spheres generate finite and countable sets of homotopy contacts of the fundamental groups. Interestingly, a compact fibre can prepare a homotopy loop in the fundamental group within the fibered topological (C, R) space. It is shown that the holomorphic condition is a requirement in the topological (C, R) space to preserve a convex path-component. However, the topological projections of p-normed 2-spheres on the disjoint holomorphic complex subspaces retain the path-connection property irrespective of the projective points on real subspace. The local fundamental groups of discrete-loop variety support the formation of a homotopically Hausdorff (C, R) space.

Competenze lessicali in italiano L2: gli eventi di moto in testi narrativi

This paper deals with a case of lexical cross-linguistic influence from a source language, known as conceptual transfer. In particular, narratives in Italian L2 produced by different L1 learners are examined. The theoretical framework adopted is lexical typology as developed by L. Talmy, according to which languages fall into two types as to how they encode motion events: The so-called verb-framed languages would tend to lexicalize the semantic component of the Path (eg the movement from inside to outside or vice versa) in the verb (eg It. uscire "to go out"); the satellite-framed languages preferentially encode the Path component outside the verb (eg in Eng. in the satellite out, as in "The boy ran out"). The preferences adopted in each L1 are supposed to influence production in L2. The presentation of the data in Italian L2 allows us to observe the subtle role that the L1s play in this lexical domain and to recommend giving attention to typological differences between L2 and L1 in the classroom.

Hybrid Model-Based and Data-Driven Diagnostic Algorithm for Gas Turbine Engines

Data-driven algorithms require large and comprehensive training samples in order to provide reliable diagnostic solutions. However, in many gas turbine applications, it is hard to find fault data due to proprietary and liability issues. Operational data samples obtained from end-users through collaboration projects do not represent fault conditions sufficiently and are not labeled either. Conversely, model-based methods have some accuracy deficiencies due to measurement uncertainty and model smearing effects when the number of gas path components to be assessed is large. The present paper integrates physics-based and data-driven approaches aiming to overcome this limitation. In the proposed method, an adaptive gas path analysis (AGPA) is used to correct measurement data against the ambient condition variations and normalize. Fault signatures drawn from the AGPA are used to assess the health status of the case engine through a Bayesian network (BN) based fault diagnostic algorithm. The performance of the proposed technique is evaluated based on five different gas path component faults of a three-shaft turbofan engine, namely intermediate-pressure compressor fouling (IPCF), high-pressure compressor fouling (HPCF), high-pressure turbine erosion (HPTE), intermediate-pressure turbine erosion (IPTE), and low-pressure turbine erosion (LPTE). Robustness of the method under measurement uncertainty has also been tested using noise-contaminated data. Moreover, the fault diagnostic effectiveness of the BN algorithm on different number and type of measurements is also examined based on three different sensor groups. The test results verify the effectiveness of the proposed method to diagnose single gas path component faults correctly even under a significant noise level and different instrumentation suites. This enables to accommodate measurement suite inconsistencies between engines of the same type. The proposed method can further be used to support the gas turbine maintenance decision-making process when coupled with overall Engine Health Management (EHM) systems.

Toward CO2 and CH4 measurements by ground-based observations of surface-scattered sunlight: Instrumentation and experiments

<div> <div>Precise knowledge of sources and sinks in the carbon cycle is desired to understand its sensitivity to climate change, and to account and verify man-made emissions. An important role herein play extended sources like urban areas. While in-situ measurements of carbon dioxide (CO<sub>2</sub>) and methane (CH<sub>4</sub>) are highly accurate but localized, satellites measure column-integrated concentrations over an extended footprint. Our innovative measurement technique aims at determining CO<sub>2</sub> and CH<sub>4</sub> concentrations on the scale of a few kilometers near the ground, and therefore fills the sensitivity gap between in-situ and satellite measurements.</div> <div> </div> <div>Our development starts out from the EM27/SUN Fourier transform spectrometer, which is a reliable, mobile and commercially available spectrometer for the measurement of CO<sub>2</sub> and CH<sub>4</sub> column densities using direct sunlight spectra. We increased the radiometric sensitivity of the instrument by enhancing optical throughput and replacing the detector module by a thermoelectrically cooled detector. This enables the measurement of surface scattered sunlight spectra in the range of 4000 - 11000 cm<sup>-1</sup> under various viewing directions. Our setup is independent of sun position and exhibits a high sensitivity to the concentrations in the lower boundary layer, due to the near ground horizontal path component.</div> <div> </div> <div>Here, we report progress on our instrumental developments, as well as first retrievals of column averaged CO<sub>2</sub> and CH<sub>4</sub> mole fractions from ground-scattered sunlight spectra recorded with this setup. We present the instrument modifications and extensions to the experimental setup: A Lambertian reflector allows for reference measurements without horizontal path component, a coaligned camera enables specific targeting and the motorized tracking system facilitates automated alternation between multiple targets. We characterize the setup with a spectral resolution of 0.54 ± 0.03 cm<sup>-1</sup> a signal to noise ratio above 200 for solar zenith angles < 85°, and precision of 1.8 ppm and 9 ppb regarding the inferred column averaged CO<sub>2</sub> and CH<sub>4</sub> mole fractions obtained from retrievals with a simple radiative transfer model, neglecting atmospheric scattering.</div> </div>

Foliations with non-compact leaves on surfaces

The paper studies non-compact surfaces obtained by gluing strips R × (−1, 1) with at most countably many boundary intervals along some of these intervals. Every such strip possesses a foliation by parallel lines, which gives a foliation on the resulting surface. It is proved that the identity path component of the group of homeomorphisms of that foliation is contractible.

Novel Techniques for Noise-Tolerance in Combinational Critical-Path Circuit Components

The continued scaling of the device and interconnect in the deep submicron jurisdiction of the complementary metal oxide semiconductor (CMOS) very large scale design (VLSI) has brought many new design challenges and exposed the limitations of the traditional VLSI design. One of the most severe problems in the deep submicron is that the circuit tend to malfunction by producing incorrect outputs in the event of inputs that have glitch. Such noise problem has emerged as the critical reliability problem in the deep submicron, in addition to the power dissipation problem. In this proposal, new research is proposed to counter the noise problem through novel circuit design techniques and methodologies. As we continue in deep submicron, the reliability of such designs is reduced as the output levels of such circuit suffer because of voltage scaling. We present our research along with the results and then describe the further proposed research. The research techniques are described using the combinatorial gates which serve as the critical path component in many designs. Also, an efficient flip-flop CD, that is conditionally discharged when there is no input changes and the input remains high to high, is proposed. This new flip-flop reduces the switching state activity, and is almost glitch-less at the output. The results from our proposed techniques demonstrate at least 2.3x the noise-immunity over the best known results in the literature.