Stabilisation of non-linear systems with unknown growth rate by adaptive output feedback

In recent years, several results have been proposed on the global stabilisation of non-linear systems with unknown linear growth rate. However, these works are limited in the sense that they consider only one particular form of non-linear systems–mostly either triangular or feedforward form. We propose an adaptive output feedback control scheme which can deal with both triangular or feedforward non-linear systems with unknown linear growth rate in a unified framework. Thus, our result broadens the class of non-linear systems under consideration over the existing results.     

Software generated device exception for more intensive device-related software testing: An industrial field study

It is more important to properly handle exceptions, than to prevent exceptions from occurring, because they arise from so many different causes. In embedded systems, a vast number of exceptions are caused by hardware devices. In such cases, numerous software components are involved in these hardware device-originated exceptions, ranging from the device itself to the device driver, the kernel, and applications. Therefore, it takes a lot of time to debug software that fails to handle exceptions. This paper proposes a lightweight device exception testing method, and a related automation tool, AMOS v3.0. The proposed method artificially triggers more realistic device exceptions in runtime, and monitors how software components handle exceptions in detail. AMOS v3.0 has been applied to the exception testing of car-infotainment systems in an automobile company. The results based on this industrial field study have revealed that 39.13% of the failures in exception handling were caused by applications, 36.23% of the failures were caused by device drivers, and 24.64% were derived from the kernel. We conclude that the proposed method is highly effective, in that it can allow developers to identify the root cause of failure for exception handling.     

An output feedback tracking controller for systems diffeomorphic to the non-linear observer form

An output feedback tracking controller is proposed for single-input, single-output non-linear systems that are diffeomorphic to the non-linear observer form. Difficulty in obtaining the output injection terms of the non-linear observer form is solved by a numerical technique and the interpolation method using the radial basis function (RBF) network. The trained RBF networks approximate output injection terms in a compact interval and are utilized for building a non-linear observer. In constructing the output tracking controller the backstepping control method is adopted based on the state estimates.     

A new framework for two loop disturbance rejection control

In this paper, a new framework of a two loop disturbance rejection control and its design methodology are proposed. The framework consists of a robust internal-loop compensator (RIC) to eliminate disturbances and an external-loop controller to achieve nominal control performance. As the main contribution of this paper, we define the design problem of the RIC as a regulation control problem, then show that this new definition with the RIC structure provides more design flexibility and less implementation constraints, which allows us to design the RIC aggressively against a specific disturbance. This is verified through a comparative structural analysis with a disturbance observer (DOB) and an adaptive robust control (ARC). Two design examples of the RIC are given, along with practical issues that should be considered in the design procedure. The proposed framework is demonstrated by simulations and experiments.     

Scratch-resistant hydrophobic and oleophobic coatings prepared by simple PECVD method

A simple and conventional PECVD method was adopted to synthesize scratch-resistant hydrophobic and oleophobic films, by varying the process condition. The film was designed to be 3 layered. The first SiOx layer was coated on the substrate using OMCTS and O₂, followed by O₂ plasma treatment; hydrocarbon-based hydrophobic film was synthesized using HMDS as a second layer; and finally, CFx-based film was coated using C₂F₆. The first and second layers were synthesized using RF power of 13.56 MHz, while MF power of 40 kHz was used for the CFx layer for ion-assisted deposition. The water contact angle was measured to be 110°–115°, and the oil contact angle was 84° for the best obtained sample. The pencil hardness was measured to be 7H for anti-scratch property. XPS was adopted to analyze the chemical structure and showed that highly cross-linked dense structured film was synthesized.     

Bonding characteristics and corrosion resistance of silane–cerium-treated aluminum adherend

A silane–cerium treatment was applied on an aluminum adherend to simultaneously improve the bonding performance and corrosion resistance of the adhesively bonded aluminum joint in cryogenic applications, such as with liquefied natural gas containment tanks. The lap shear strengths and corrosion performances of the adhesively bonded joints composed of treated aluminum adherends were measured with respect to the silane–cerium treatment and the surface pretreatment on the aluminum adherend. The bonding characteristics of the aluminum adherend were investigated by measuring the water contact angle and conducting the potentiodynamic polarization test after the aluminum adherends with different surface treatments of silane–cerium were immersed in a 0.5?M NaCl solution. In addition, the surfaces were analyzed with scanning electron microscopy, X-ray photoelectron spectroscopy, and Fourier transform infrared spectroscopy to characterize the chemical compositions of the silane–cerium-treated aluminum adherend. The experimental results show that an appropriate silane–cerium treatment on the aluminum adherend produces an effective corrosion-resistant layer and that it has a highly reliable bonding characteristic for the adhesive joint at a cryogenic temperature of ?150?°C.     

Strain effect on recovery behaviors from circular deformation of natural rubber vulcanizate

The recovery behaviors of vulcanized natural rubber from circular deformation were studied by varying sample length to investigate the influence of the degree of applied strain to the sample. The stress and strain varied uniformly across the thickness of the sample, and the degree of applied stress and strain to the sample decreased with increasing the sample length. The linear sample was made into a circular form and thermally aged in a convection oven. The recovery was measured after removing from the circular deformation. The recovery increased by decreasing the sample length. The difference in recoveries of the samples with different lengths reduced at high temperature. The short sample had higher heat‐resisting property for recovery than the long sample. The experimental results were explained by the rearrangement and stabilization of the deformed rubber chains as well as the crosslink density change. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

On a class of branching problems in broadcasting and distribution

We introduce the following network optimization problem: given a directed graph with a cost function on the arcs, demands at the nodes, and a single source s, find the minimum cost connected subgraph from s such that its total demand is no less than lower bound D. We describe applications of this problem to disaster relief and media broadcasting, and show that it generalizes several well-known models including the knapsack problem, the partially ordered knapsack problem, the minimum branching problem, and certain scheduling problems. We prove that our problem is strongly NP-complete and give an integer programming formulation. We also provide five heuristic approaches, illustrate them with a numerical example, and provide a computational study on both small and large sized, randomly generated problems. The heuristics run efficiently on the tested problems and provide solutions that, on average, are fairly close to optimal.