A 1.8-V 2.4/5.15-GHz dual-band LCVCO in 0.18-/spl mu/m CMOS technology

A dual band, fully integrated, low phase-noise and low-power LC voltage-controlled oscillator (VCO) operating at the 2.4-GHz industrial scientific and medical band and 5.15-GHz unlicensed national information infrastructure band has been demonstrated in an 0.18-/spl mu/m CMOS process. At 1.8-V power supply voltage, the power dissipation is only 5.4mW for a 2.4-GHz band and 8mW for a 5.15-GHz band. The proposed VCO features phase-noise of -135dBc/Hz at 3-MHz offset frequency away from the carrier frequency of 2.74GHz and -126dBc/Hz at 3-MHz offset frequency away from 5.49GHz. The oscillator is tuned from 2.2 to 2.85GHz in the low band (2.4-GHz band) and from 4.4 to 5.7GHz in the high band (5.15-GHz band).     

Generalized patchwork algorithm for image watermarking

This paper presents the generalized patchwork algorithm (GPA), which is an extension of the modified patchwork algorithm (MPA). The MPA embeds watermarks additively and changes the mean of the pixels accordingly. In this paper, we take multiplicative watermarks into consideration where the GPA can change the variance of pixels. The GPA combines both additive watermarks and multiplicative watermarks. The embedding functions of the GPA determine embedding parameters adaptively according to the host signals. Detection functions also determine thresholds adaptively. Embedding and detection functions based on the test of statistical hypotheses are presented in this paper. Simulation results show the effectiveness of the GPA. The proposed algorithm is sufficiently robust against various signal processing operations, especially against compression attacks.     

Signal Processing for Large Bandwidth and Long Duration Waveform SAR

We first show that for some kinds of signals a bandwidth and time duration reduction technique can be used to simulate waveform distortions caused by moving targets, that is, it is correct to measure the waveform distortions at very large TB with relatively small by reducing TB and increasing while keeping TB unchanged, where T is the duration of the transmitted signal, B is the bandwidth and is the relative speed of targets. We then study the waveform distortions in SAR signals caused by moving antenna. Based on the bandwidth and time duration reduction technique, a lot of time and memory are saved in simulations. We then confirm by simulations that waveform distortions do pose problems when processing very large bandwidth and long duration SAR data using conventional SAR processing methods. Finally we propose the concepts of wideband and narrowband processing of SAR data. Models are set up for wideband and narrowband SAR data processing, and new methods are presented for reconstructing targets using the proposed models. Simulations show that the methods can improve the quality of the simulated SAR images.     

Analytical profiling of biosynthetic intermediates involved in the gentamicin pathway of Micromonospora echinospora by high-performance liquid chromatography using electrospray ionization mass spectrometric detection

In the present study, we developed a sensitive and highly selective method of detecting the biosynthetic intermediates involved in the gentamicin pathway from a cell culture of Micromonospora echinospora. A novel extraction method utilizing a dual solid-phase extraction (SPE) technique was employed to purify and recover all of the gentamicin-related components from the cell culture broth, and high-performance liquid chromatography (HPLC) coupled with electrospray ionization mass spectrometry (ESI-MS/MS) was used to analyze the extractant for gentamicin intermediates. The pH of the culture broth was adjusted to an acidic condition of pH 2 prior to the extraction. The samples were first cleaned with a reversed-phase AccuBOND C(18) cartridge, and then the aminoglycosidic components were purified using a cationic exchanger OASIS MCX cartridge. The detection limit of a gentamicin standard spiked in blank medium processed by this method was found to be approximately 5 ng for each component of the gentamicin C complex, and the mean recovery for each component of standard gentamicin was above 91% when analyzed by HPLC-ESI-MS/MS. We further demonstrated that this method enables the analytical profiling of the gentamicin-related compounds produced by wild-type M. echinospora ATCC 15835, which mainly produces the gentamicin C complex, and the UV-induced mutant strain KCTC 10506BP, which produces gentamicin B as the major product. Seven intermediates (paromamine, gentamicin A2, B, X2, A, JI-20A, and JI-20B) besides the gentamicin C complex were detected in the culture broth of both M. echinospora strains when analyzed by MS/MS for the distinct fragmentation patterns of each gentamicin component. This report displays the first example of the HPLC profiling in a wide range of structurally related biosynthetic intermediates involved in the gentamicin pathway.     

The Linear Arrangement Problem Parameterized Above Guaranteed Value

A linear arrangement (LA) is an assignment of distinct integers to the vertices of a graph. The cost of an LA is the sum of lengths of the edges of the graph, where the length of an edge is defined as the absolute value of the difference of the integers assigned to its ends. For many application one hopes to find an LA with small cost. However, it is a classical NP-complete problem to decide whether a given graph G admits an LA of cost bounded by a given integer. Since every edge of G contributes at least one to the cost of any LA, the problem becomes trivially fixed-parameter tractable (FPT) if parameterized by the upper bound of the cost. Fernau asked whether the problem remains FPT if parameterized by the upper bound of the cost minus the number of edges of the given graph; thus whether the problem is FPT "parameterized above guaranteed value." We answer this question positively by deriving an algorithm which decides in time O(m + n + 5.88^k) whether a given graph with m edges and n vertices admits an LA of cost at most m + k (the algorithm computes such an LA if it exists). Our algorithm is based on a procedure which generates a problem kernel of linear size in linear time for a connected graph G. We also prove that more general parameterized LA problems stated by Serna and Thilikos are not FPT, unless P = NP.     

Development of least-square-based two-dimensional finite-difference schemes and their application to simulate natural convection in a cavity

In this paper, two-dimensional mesh-free finite-difference schemes for solving incompressible viscous flows are presented. The method is based on the use of a weighted least-square approximation procedure together with a Taylor series expansion of the unknown function. Discretization error for derivatives is investigated analytically on the uniform mesh and the convergence property of the method is numerically tested. The role of the weighting function playing in the method is studied. Neumann-type boundary condition is treated by applying locally orthogonal boundary grids. Application to a problem of natural convection in a cavity is demonstrated on three different types of point distribution.     

A 20‐node hexahedron element with enhanced distortion tolerance

This paper presents a distortion resistant 20‐node hexahedron element that employs two different sets of shape functions for the trial and test functions. The formulation seeks to satisfy the continuity and completeness requirements by exploiting the intrinsic properties of these two sets of shape functions. Several test problems are used to assess the performance of the element under various mesh distortions. The ability of the proposed as well as the classical 20‐node element to maintain solution accuracy under severe mesh distortions has been studied. The proposed element exhibits a very high tolerance to mesh distortions. In particular, for problems involving linear and quadratic displacement fields, the element is capable of reproducing exact solution under all admissible geometrical distortions of the mesh. For test problems involving higher‐order displacement fields, the performance of the present element is in general better than that of the classical element. Copyright © 2004 John Wiley & Sons, Ltd.     

Path and Oracle Discovery Protocol for Centralized Bandwidth Reservation Mechanisms

The introduction of Differential Service architecture has initiated interests in centralized bandwidth reservation via an oracle with each network domain defining its own oracle. The centralized bandwidth reservation mechanism requires knowledge of network topology and reservation paths in the domain to control access to premium services as well as log usage. We propose a new reactive protocol, Path and Oracle Discovery Protocol (PODP), to facilitate the management of networks with centralized bandwidth reservations. This protocol discovers the routers traversed by the network connection request and the respective domain oracle. PODP is able to respond to network path changes at minimum network overhead and storage requirements compared to other methods. A prototype router and oracle supporting the PODP has been successfully developed and tested across multiple domains.     

Elastic mesh technique for 3D BIM simulation with an application to underwater explosion bubble dynamics

The proposed elastic mesh technique (EMT) is a mesh regulation technique, which is based on the assumption that the segments of a mesh are elastic. EMT can be employed in conjunction with the boundary integral method (BIM) for the simulation of three-dimension bubble dynamics in which problems relating to severe mesh distortion as the bubble evolves are a common occurrence. With EMT, the mesh is advanced not by the material velocity, but the optimum shift velocity obtained by minimizing the total elastic energy stored in every segment of the mesh at each time step. In doing so, the prohibitively small time stepping associated with small meshes without EMT in order to maintain numerical stability is mitigated to a large extent. An important feature is that the EMT scheme accords the user the flexibility to implement a non-uniform optimum constitutive relation governing the elastic behavior of mesh segment and which can be further varied with time. Tests were performed for an underwater explosion bubble exhibiting the dynamics of strong jet development with and without EMT for comparison, and the consideration of incorporating EMT as a hybrid system serving as an alternative to the required mesh refinement which is computationally intensive. A full three-dimension simulation of explosion bubble(s) and in the presence of the free surface were further carried out to elucidate the associated flow physics.     

A method for connecting solution-phase enzyme activity assays with immobilized format analysis by mass spectrometry

This paper reports an enzyme activity assay that combines the assets of both homogeneous and solid-phase formats. In this method, enzyme reactions are carried out in solution using substrates that are tagged with an immobilization reagent that allows the substrates to be selectively immobilized to self-assembled monolayers (SAMs), for direct analysis by matrix assisted laser desorption ionization time-of-flight (MALDI-TOF) mass spectrometry (MS). As a model enzyme reaction, this work examined the transfer of a methyl group from S-adenosyl-l-methionine (AdoMet) to an arginine side chain of a peptide substrate by the enzyme protein arginine methyltransferase 1 (RMT1). A cysteine-terminated peptide substrate was methylated by RMT1 in solution and then applied to a maleimide-presenting SAM to give selective immobilization of the peptide. Time-dependent analysis of methylation using MALDI-TOFMS clearly showed that both the presence and relative amount of the two reaction products-the mono- and dimethylated peptides-can be conveniently evaluated. This assay strategy is rapid, takes advantage of solution-phase assay conditions, avoids the use of labels and complicated purification steps, and is applicable to multianalyte analyses.