Comments on “The Cramer-Rao lower bounds for signals withconstant amplitude and polynomial phase”

For original paper see IEEE Trans. Signal Processing, vol.39, p.749-52 (March 1991). Different expressions for the Cramer-Rao lower bounds (CRLBs) of constant amplitude polynomial phase signals embedded in white Gaussian noise appear in the literature. The present paper revisits the derivation of the bounds reported by Peleg and Porat (1991) and indicates that the resulting expressions depend on the interval over which the signal is defined. The proper choice of the interval is the one that centers the signal around zero and results in the minimum lower bounds     

Thermal Processes During Mechanical Treatment of ZnO and ZnO-TiO2 Powders and their Role in the Formation of Defect Structure

We used electron paramagnetic resonance (EPR) to determine the dependence of the defect structure of zinc oxide powders on the physical characteristics of admixed particles during prolonged mechanical treatment (MT). Our results demonstrate a sequential two-stage thermal process contributing to the defect structure during MT. In the first stage of MT a collective break-up process of individual ZnO particles occurs and the defects are caused by hyper-rapid thermal defects annealing (HRTDA) of the particles. The second stage of defect formation is associated with annealing effects caused by heat accumulation.     

Fast and accurate NURBS fitting for reverse engineering

Fast and accurate fitting of non-uniform rational B-spline (NURBS) curves and surfaces through large sets of measured data is an important problem in applications such as reverse engineering and geometric modelling. This paper presents a method for realising significant improvements in the computational efficiency of this task. The basic idea is that the sparsity structures of the relevant matrices that are specific to the problem of NURBS fitting can be precisely defined and that full exploitation of these structures leads to significant savings in both computational and storage requirements. These savings allow for a large number of control points to be used in order to define the surface and consequently to improve the accuracy of shape representation. The achieved computational complexity is linear in both the number of measured points and the number of control points while the storage requirements of the algorithm are linear with the number of control points only. The complexity analysis, as well as the analysis of actual running times is presented. The results demonstrate that, using this approach, highly complex shapes may be modelled accurately with a single NURBS surface.     

All-optical erasable programmable read-only memory (EPROM) based onLiNbO3 channel waveguides

The erasable programmable read-only memory (EPROM) consists of three channel waveguides. Two are made by the proton-exchange technique to construct a directional coupler as the read-in and read-out units. The third, placed in between the other two, is made by the Ti-indiffusion technique to function as the memory storage unit as well as the control channel. The operation principle is based on the combination of the directional coupler switch and the photorefractive effect. The EPROM also operates as an all-optical switch if a short-pulsed laser with high-energy density is used to write and erase, and the speed should be on the nanosecond time scale or even faster. Theoretical calculation of some typical designs shows that very small light energy (0.06-0.6 mJ) is needed for the device operation     

G. V. Samsonov’s search for the essential nature of the sintering process

We present the original concepts of sintering developed by G. V. Samsonov. The concepts under discussion represent the fundamental concepts of the electronic theory of sintering. Momcilo M. Ristic. Well-known Yugoslavian scientist. Professor. Academician of the Serbian Academy of Arts and Sciences. foreign member of the Ukrainian Academy of Sciences, foreign member of the Russian Academy of Technical Sciences, foreign member of the Macedonian Academy of Arts and Sciences, honorary member of the Serbian Chemical Society, honorary member of the International Biographical Institute, member of the American Ceramic Society, organizer and active member of the International Institute for the Science of Sintering. Serbian Academy of Arts and Sciences, Belgrade. Translated from Poroshkovaya Metallurgiya. Nos. 1–2, pp. 12–16, January–February, 1998.     

Cramer-Rao bound for nonlinear filtering with Pd<1 and itsapplication to target tracking

The paper investigates the Cramer-Rao bound for discrete-time nonlinear filtering in the case where the probability of detection of a sensor is less than unity. The theoretical formula involves the evaluation of exponentially growing number of possible miss/detection sequences. An approximation of the theoretical bound for practical applications, such as target tracking, where the number of sensor scans is large, is proposed. An application of the developed techniques to the well-known filtering problem of tracking a re-entry ballistic object is also presented     

Effect of radiation-induced oxide-trapped charge on mobility inp-channel MOSFETs

It is shown that radiation-induced oxide-trapped charge contributes to an increase in mobility in p-channel MOSFETs. A new scattering mechanism involving retardation of surface-roughness scattering due to oxide-trapped charge is proposed in order to explain the observed mobility increase     

The preparation and properties of zinc coordination complexes of poly(4-vinylpyridine-co-n-butyl methacrylate) copolymers

Two poly(4-vinylpyridine-co-n-butyl methacrylate) copolymers containing 14.2 and 30.0 mol% of 4-vinylpyridine residues were prepared by free radical copolymerization reactions. Insoluble complexes were obtained for each copolymer by reaction with zinc chloride. The coordination complexes obtained had a molar ratio of 4-vinylpyridine residues to zinc atoms close to 2 in both cases. The rheological behavior of each of these complexes has been compared to that of the corresponding metal-free copolymers, which were recovered by decomplexation. The metal complexed polymers exhibited much higher glass transition temperatures and much longer high temperature relaxation times than the corresponding uncomplexed copolymers.     

Experimental study of anisotropy dependent geodesic lenses

The effect of anisotropy on focal lengths of geodesic lenses has been investigated with a novel experimental method. The measured relative difference for TE and TM (transverse electric and transverse magnetic)-mode focal lengths, for 10° off-axis propagation, was 6.33%; this compares well with the theoretical prediction of 6.6%     

A CAD/CAM system for die design and manufacture

The manufacture of directionally solidified cast turbine blades relies on the precise casting of wax patterns of the actual turbine blade. This, in turn, requires the design and manufacture of a complex die. A CAD/CAM system is presented specifically for producing manufacturing information for dies based on basic data defining the shape of a turbine blade. The system is based around a UNIX graphics workstation which forms part of a CIM system being developed as part of an SERC Teaching Company based at Rolls-Royce plc, Derby.