Robust Fault Detection and Isolation Based on Finite-frequency H?/H∞ Unknown Input Observers and Zonotopic Threshold Analysis

This work proposes a robust fault detection and isolation scheme for discrete-time systems subject to actuator faults, in which a bank of H₋/H_∞ fault detection unknown input observers (UIOs) and a zonotopic threshold analysis strategy are considered. In observer design, finite-frequency H₋ index based on the generalized Kalman-Yakubovich-Popov lemma and H_∞ technique are utilized to evaluate worst-case fault sensitivity and disturbance attenuation performance, respectively. The proposed H₋/H_∞ fault detection observers are designed to be insensitive to the corresponding actuator fault only, but sensitive to others. Then, to overcome the weakness of predefining threshold for FDI decision-making, this work proposes a zonotopic threshold analysis method to evaluate the generated residuals. The FDI decision-making relies on the evaluation with a dynamical zonotopic threshold. Finally, numerical simulations are provided to show the feasibility of the proposed scheme.     

NOx adsorption behavior of LaFeO3 and LaMnO3+δ and its influence on potentiometric sensor response

NO_x adsorption behavior on LaFeO₃ (LFO) and LaMnO_3+δ (LMO) was characterized using temperature controlled methods and mass spectrometry. Temperature program desorption revealed decomposition of complex surface species formation when NO or NO₂ was adsorbed on LFO and LMO. LFO exhibited higher adsorption capacity for NO_x species than LMO and was shown to be more active for NO_x surface conversion. Both effects were attributed to the different B-site cations, with iron in LFO in the 3+ valence state, and manganese in LMO in the 3+ and 4+ valence states. Results from diffuse reflectance infrared spectroscopy were used to identify specific nitrite and nitrate species that are formed on the surfaces of LFO and LMO at room temperature. Temperature programmed reaction revealed a complex NO₂ decomposition mechanism to NO and O₂ for LFO and LMO in which the formation of nitrite and nitrate species serve as intermediates below ∼600 °C. NO_x sensing mechanisms were considered and predicted based on the types and quantities of surface species formed.     

Biomass measurements and relationships with Landsat‐7/ETM+ and JERS‐1/SAR data over Canada's western sub‐arctic and low arctic

Information on biomass distribution is needed to estimate GHG emissions and removals from land use changes in Canada's north for UNFCCC reporting. This paper reports aboveground biomass measurements along the Dempster Highway transect in 2004, and around Yellowknife and the Lupin Gold Mine in 2005. The measured aboveground biomass ranges are 10–100 t ha^?1 for woodlands, 1–100 t ha^?1 for shrub sites, and 0.5–10 t ha^?1 for grass/herbs sites. The root mean squared error (RMSE) of measurements is 21%, and the median absolute percentage error (MedAPE) is 14%. The combination of JERS backscatter and Landsat TM4/TM5 gives the best biomass equation for the Dempster Highway transect, with r ² = 0.72 when using a one‐step approach (i.e. using all points) and 0.78 when using a two‐step approach (i.e. stratifying data into three classes: grass, shrub, and woodlands). The two‐step approach reduces the MedAPE from 53% to 33%. The validation against Yellowknife & Lupin data indicates that the equations have good transferability. The improvement of two‐step approach over the one‐step approach, however, is not significant for the validation dataset, suggesting that the one‐step approach is as good as the two‐step approach when applied over areas outside where the equations are developed. The relationships and error analysis of this study, as well as the final estimate of GHG emission/removal over Canada's north have been incorporated into Canada's 2006 UNFCCC report.     

Self-Monitoring Machines and anωHierarchy of Loops

An ordinal hierarchy of recursive functions is developed based on the level to which a function requires a machine computing it to monitor and make decisions concerning itself. The major theorem states that the functions with self-monitoring level belowω^ωare precisely the class of loop functions (or primitive recursive functions).     

α-MoO3/TiO2 core/shell nanorods: Controlled-synthesis and low-temperature gas sensing properties

Crystalline α-MoO₃/TiO₂ core/shell nanorods are fabricated by a hydrothermal method and subsequent annealing processes under H₂/Ar flow and in the ambient atmosphere. The shell layer is composed of crystalline TiO₂ particles with a diameter of 2-6 nm, and its thickness can be easily controlled in the range of 15-45 nm. The core/shell nanorods show enhanced sensing properties to ethanol vapor compared to bare α-MoO₃ nanorods. The sensing mechanism is different from that of other one-dimensional metal oxide core/shell nanostructures due to very weak response of TiO₂ nanoparticles to ethanol. The enhanced sensing properties can be explained by the change of type II heterojunction barrier formed at the interface between α-MoO₃ and TiO₂ in the different gas atmosphere. The present results demonstrate a novel sensing mechanism available for gas sensors with high performance.     

Using Pro/E and ANSYS to Build Finite Element Models

1 Introduction Pro/E, a well-known software package for three-dimensional part design, is the key product of American PTC Company. It has been adopted as a new standard for CAD/CAE/CAM and widely used in mechanical design around the world. Pro/E software has powerful functions and excellent versatility. It supports complex part design, mould design, sheet-metal part design, assembly modeling, NC machining and processing, finite element analysis, mechanical simulation analysis, and more…     

Hessenberg and Hessenberg/triangular forms in linear system thcory†

In this paper we distinguish between free Hessenberg forms, where only the system matrix is transformed into a special structure, and system Hessenberg forms, where either an input or output matrix is simultaneously simplified. We show how the freedom in the choice of the transformation matrix for the free Hessenberg form can be used to obtain a unique system Hessenberg form. We discuss numerical aspects and outline some basic applications for both types of Hessenberg forms in control and system theory. We show that the system Hessenberg form can be extremely sensitive to perturbations, a property not necessarily shared by the free Hessenberg form. Several examples are explored, and a first-order perturbation analysis is given. Analogous aspects are also discussed for the Hessenberg/triangular forms resulting from reduction of a matrix pencil. The main emphasis of this paper is on systems with one input.     

On Model, Memory Management and Interface in EDBMS/3

Engineering application domains need database management systems to supply them with a good means of modeling,a high data access efficiency and a language interface with strong functionality.This paper presents a semantic hypergraph model based on relations,in order to express many-to-many relations among objects belonging to different semantic classes in engineering applications.A management mechanism expressed by the model and the basic data of engineering databases are managed in main memory.Especially,different objects are linked by different kinds of semantics defined by users,therefore the table swap,the record swap and some unnecessary examinations ar reduced and the access efficiency of the engineering data is increased.C language interface that includes some generic and special functionality is proposed for closer connection with application programs.     

Structure and humidity sensing properties of La1−xKxCo0.3Fe0.7O3−δ perovskite

The effects of K-substitution at La-site of La_1−xK_xCo_0.3Fe_0.7O_3-δ perovskite on its structure and humidity sensing properties were studied in detail. The XRD, SEM-EDS, N₂ adsorption-desorption measurements (BET), ICP-AES and XPS were used to characterize the microstructure of La_1−xK_xCo_0.3Fe_0.7O_3−δ perovskite. The results show that the partial substitution of K at La-site has no obvious effect on the crystal phase, morphology and surface area of samples, but leads to the increased oxygen vacancies and surface enriched K⁺. The sensitivity of humidity sensor based on all samples was evaluated by measuring the impedance response to the humidity changes. The partial substitution of K at La-site significantly enhanced the humidity sensitivity of La_1−xK_xCo_0.3Fe_0.7O_3−δ perovskite at low relative humidity (RH). By correlating the structure of material with its sensing properties, the probable reasons that lead to the remarkable sensitivity enhancement of the K-substitution samples compared with the unsubstituted sample (LaCo_0.3Fe_0.7O_3−δ) were given; moreover, the sensing mechanism was also discussed by the complex impedance spectra in detail.     

Vertex fault tolerance of optimal-κ graphs and super-κ graphs

A connected graph G is optimal-κ if κ(G)=δ(G). It is super-κ if every minimum vertex cut isolates a vertex. An optimal-κ graph G is m-optimal-κ if for any vertex set S⊆V(G) with |S|?m, G−S is still optimal-κ. We define the vertex fault tolerance with respect to optimal-κ, denoted by Oκ(G), as the maximum integer m such that G is m-optimal-κ. The concept of vertex fault tolerance with respect to super-κ, denoted by Sκ(G), is defined in a similar way. In this paper, we show that min{κ₁(G)−δ(G),δ(G)−1}?Oκ(G)?δ(G)−1 and min{κ₁(G)−δ(G)−1,δ(G)−1}?Sκ(G)?δ(G)−1, where κ₁(G) is the 1-extra connectivity of G. Furthermore, when the graph is triangle free, more refined lower bound can be derived for Oκ(G).     

Simultaneous MSMR and SSM/I observations and analysis of sea‐ice characteristics over the Antarctic region

Polar sea ice has been monitored quasi‐continuously over the last 30 years using passive microwave radiometers onboard three satellites in polar orbit, namely Nimbus‐5, Nimbus‐7 and Defense Meteorological Satellite Program (DMSP) series. A short overlap between Scanning Multichannel Microwave Radiometer (SMMR) on Nimbus‐7 and Special Sensor Microwave Imager (SSM/I) onboard DMSP allowed inter‐calibration of the two sensors leading to a consistent series of long‐term sea‐ice measurements since 1978. With the launch of Multifrequency Scanning Microwave Radiometer (MSMR) onboard OCEANSAT‐1 in the polar sun‐synchronous orbit during 1999, India developed the capability to monitor the polar sea ice on a regular basis. The concurrent availability of SSM/I and MSMR over the last few years presents a valuable opportunity to attempt an inter‐comparison of MSMR with SSM/I measurements and derived sea‐ice parameters.

In this paper, we present an indirect validation of the brightness temperatures (T _b) observed by MSMR with near‐simultaneous measurements from SSM/I over the Antarctic and Southern Polar Ocean regions. Simultaneous MSMR and SSM/I data from two contrasting seasons—summer and winter—for the 1999–2000 period have been used. Analysis includes a comparison of T _b scatterograms to achieve confidence in the quantitative use of the T _b data to derive various geophysical parameters, e.g. sea‐ice concentration and extent. Additionally, the T _b images produced by the two sensors are compared to establish the capability of MSMR in reliable two‐dimensional portrayal of all the sea and continental ice features over the Antarctic Region. Based on a regression analysis between MSMR observed T _b in different frequency channels and polarizations, and SSM/I‐derived sea‐ice concentration (SIC) values, we have developed algorithms to estimate SIC over the Southern Polar Ocean from MSMR data. The MSMR algorithms allow estimation of SIC with better than 10% rms error. MSMR SIC images faithfully capture the observed distribution of sea ice in all the sectors of the Southern Ocean both during summer and winter periods. Using the MSMR‐derived SIC, we have also derived monthly sea‐ice extent (SIE) estimates for a period extending for about 20 months from the beginning of the launch of MSMR. These estimates show excellent agreement with values derived from SSM/I. These analyses bring out the very high level of compatibility in the measurements and derived sea‐ice parameters produced by the two sensors.     

A New Taxonomy of Linux/Unix Operating System and Network Vulnerabilities

This paper analyzes the existing taxonomies of software vulnerability, describes the actuality of researches on software vulnerability. Then this paper lists the major characters describing software vulnerabilities, which include cause, location, impact, remedy, verification, detect and attack characters. For Unix/Linux operation systems, this paper proposes a two-dimensional taxonomy of software vulnerability based on location and cause attributes, describes the choosing reason of taxonomic attributes, and the classification scheme is described in detail. Design vulnerabilities are important class of vulnerabilities, but no classification identifies the types of design vulnerabilities in further detail yet, so this paper pays attention to design vulnerabilities.     

Stationary IPA estimates for nonsmooth G/G/1/∞ functionals via palm inversion and level-crossing analysis

We give stationary estimates for the derivative of the expectation of a nonsmooth function of bounded variationf of the workload in a G/G/1/ queue, with respect to a parameter influencing the distribution of the input process. For this, we use an idea of Konstantopoulos and Zazanis [1992] based on the Palm inversion formula, however avoiding a limiting argument by performing the level-crossing analysis thereof globally, via Fubini's theorem. This method of proof allows to treat the case where the workload distribution has a mass at discontinuities off and where the formula of Konstantopoulos and Zazanis [1992] has to be modified. The case where the parameter is the speed of service or/and the time scale factor of the input process is also treated using the same approach.This article has been presented at the 31 st IEEE CDC, Dec. 16–18, 1992, Tucson, Arizona.     

Synthesis and gas sensing properties of bundle-like α-Fe2O3 nanorods

Bundle-like α-Fe₂O₃ nanostructures were successfully synthesized by a simple calcination of β-FeOOH precursor derived from a hydrothermal method in the presence of poly(vinyl pyrrolidone). The as-prepared products were characterized by X-ray power diffraction, field emission scanning electron microscopy, and transmission electron microscopy. The results indicated that bundle-like nanostructures were composed of well-aligned single crystalline nanorods with the diameters of 20-30 nm and the lengths of 200-300 nm. The gas sensing properties of as-prepared products were investigated. It was found that the sensor based on α-Fe₂O₃ nanostructure exhibited high response, quick response-recovery, and good repeatability to acetone at 250 °C.     

Computation of Peak Output for Inputs Restricted in L2 and L∞ Norms Using Finite Difference Schemes and Convex Optimization

Control systems designed by the principle of matching gives rise to problems of evaluating the peak output. This paper proposes a practical method for computing the peak output of linear time-invariant and non-anticipative systems for a class of possible sets that are characterized with many bounding conditions on the two- and/or the infinity-norms of the inputs and their derivatives. The original infinite-dimensional convex optimization problem is approximated as a large-scale convex programme defined in a Euclidean space, which are associated with sparse matrices and thus can be solved efficiently in practice. The numerical results show that the method performs satisfactorily, and that using a possible set with many bounding conditions can help to reduce the design conservatism and thereby yield a better match.     

On the Euler sequence spaces which include the spaces ?p and ?∞ I

In the present paper, we introduce the Euler sequence space consisting of all sequences whose Euler transforms of order r are in the space ?_p of non-absolute type which is the BK-space including the space ?_p and prove that the spaces and ?_p are linearly isomorphic for 1 ? p ? ∞. Furthermore, we give some inclusion relations concerning the space . Finally, we determine the α-, β- and γ-duals of the space for 1 ? p ? ∞ and construct the basis for the space , where 1 ? p < ∞.     

Solving the generalized sylvester matrix equation Σ i=1p AiXBi + Σ j=1q CjYDj=E over reflexive and anti-reflexive matrices

A matrix P ∈ ℝ ^n×n is called a generalized reflection if P ^T = P and P ²=I. An n×n matrix A is said to be a reflexive (anti-reflexive) with respect to P if A PAP (A = −PAP). In the present paper, two iterative methods are derived for solving the generalized Sylvester matrix equation Σ _i=1 ^p A _i XB _i + Σ _j=1 ^q C _j YD _j =E (including the Sylvester and Lyapunov matrix equations as special cases) over reflexive and anti-reflexive matrices respectively. It is proven that the iterative methods, respectively, consistently converge to the reflexive and anti-reflexive solutions of the matrix equation for any initial reflexive and anti-reflexive matrices. Finally, a numerical example is given to demonstrate the effectiveness of the derived methods.     

V International Conference and Exhibition “Computer-Aided Design and Manunfacture Product Data Manager (CAD/CAM/PDM-2005)” October 25–27, 2005

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V International Conference and Exhibition “Computer-Aided Design and Manunfacture Product Data Manager (CAD/CAM/PDM-2005)” October 25–27, 2005