A Product–Delay algorithm for graphic design

A Product–Delay algorithm is presented for creating graphic designs on a computer. In this algorithm two functions u(t) and v(t) are multiplied yielding a function x(t). Another function y(t) is formed by delaying or advancing x(t) by a fixed amount of time t. These functions are evaluated over a suitable time interval and the results are plotted in the x–y plane. For appropriate choices of the functions and parameters, the x–y displays exhibit interesting geometric patterns. In this paper the algorithm is illustrated with a pair of sine and square waves. It is shown that a wide variety of graphic designs can be created with these simple waveforms. By virtue of its simplicity this algorithm can be programmed easily and quickly using general purpose software such as Maple, Matlab or Mathematica. It can be executed on standard platforms such as IBM PC compatibles, Macintosh computers or workstations. Some results in polar coordinates are also given.     

Bainite morphologies in a 0.2 C–1.5 Mn steel

The isothermal transformation products of austenite over a wide range of temperatures and times in the bainitic range in a 0.2 wt.% C–1.5 wt.% Mn steel have been studied by transmission electron microscopy in order to characterise the bainitic microstructures in low-carbon low-alloy steels. Widmanstätten ferrite has formed with alternate layers of austenite (martensite) as a transition product at 600 and 500°C that has finally transformed on further isothermal transformation to either pearlite (at 600°C) or upper bainite (at 500°C). This type of transformation product was referred to as BI bainite by earlier investigators, but on the basis of the present investigation it is concluded that such ferrite-austenite (martensite) structures are not bainitic as this is not the final transformation product either at 600 or 500°C. Both upper bainite and lath-type lower bainite are formed at 450°C while the transformation product has been only lath-type lower bainite at 400°C.     

Performance management of manufacturing system networks

Performance management of communication networks is critical for speed, reliability, and flexibility of information exchange between different components, subsystems, and sectors (e.g., factory, engineering design, and administration) of production process organizations in the environment of computer integrated manufacturing (CIM). Essential to this distributed total manufacturing system is the integrated communications network over which the information leading to process interactions and plant management and control is exchanged. Such a network must be capable of handling heterogeneous traffic resulting from intermachine communications at the factory floor, CAD drawings, design specifications, and administrative information. The objective is to improve the efficiency in handling various types of messages, e.g., control signals, sensor data, and production orders, by on-line adjustment of the parameters of the network protocol.This paper presents a conceptual design, development, and implementation of a network performance management scheme for CIM applications including flexible manufacturing. The performance management algorithm is formulated using the concepts of: (1) Perturbation analysis of discrete event dynamic systems; (2) stochastic approximation; and (3) learning automata. The proposed concept for performance management can also serve as a general framework to assist design, operation, and management of flexible manufacturing systems.The performance management procedure has been tested via emulation on a network test bed that is based on the manufacturing automation protocol (MAP) which has been widely used for CIM networking. The conceptual design presented in this paper offers a step forward to bridging the gap between management standards and users' demands for efficient network operations since most standards such as ISO and IEEE address only the architecture, services, and interfaces for network management.This work was supported in part by National Science Foundation under Research Grant No. DDM-90-15173.     

An application of wavelet analysis to paleoproductivity records from the Southern Ocean

We have performed wavelet analysis of the paleoproductivity records from the southeastern Atlantic sector of the Southern Ocean. In particular, we have applied a continuous wavelet transform to the phosphorus-to-titanium (P/Ti) ratios obtained from the Ocean Drilling Program (ODP) Sites 1089 and 1094 over the past ～600 kyr, and computed their wavelet power spectra in order to elucidate the spectral–temporal aspects of phosphorus deposition at these sites. Because data are unevenly sampled in time, they are first resampled using a uniform sampling interval prior to wavelet analysis. The wavelet power spectra of the P/Ti data are presented on a time-period plane from which the dominant periodicities of P export and their duration in time are discerned by visual inspection. Our results indicate that at the ODP Site 1089, the strongest P export occurs within a periodic band with the most dominant period of ～100 kyr, which corresponds to the eccentricity period of Milankovitch cyclicity. On the other hand, at the ODP Site 1094, which is completely covered with ice during the glacial times, the strongest periodicity of P export is found to be around 82 kyr. This periodicity is twice the period of the 41-kyr Milankovitch obliquity cycle, implying that obliquity forcing drives the productivity at this site in a period doubling scenario. Given the strong influence of ice cover at this site, another implication is that sea ice extent itself is strongly influenced by the obliquity signal, and productivity simply responds to the availability of ice-free conditions. We have also performed wavelet analysis of the carbonate production data at the ODP Site 1089, and found a dominant periodicity of ～100 kyr. In addition, a few weaker decadal-scale periodicities are observed in both P/Ti and carbonate data which can be linked to Milankovitch cycles.     

A new characterization technique for trimethylsilylated products of old cement pastes

Twenty-year-old and laboratory-prepared completely hydrated cement pastes were investigated by the trimethylsilylation technique. The resulting derivatives were separated by both gas and gel permeation chromatography (GPC). Separation of the non-volatile fraction of the trimethylsilyl derivatives was more efficient by the GPC technique. The trimethylsilyl derivatives of SiO₄^4? and Si₂O₇^6? ions were easily identified by GPC. The constitutions of the other silicate anion derivatives separated by GPC were inferred on the basis of their molecular weights, relative to those of SiO₄^4? and Si₂O₇^6? ions.     

PAPR reduction using twin symbol hybrid optimization-based PTS and multi-chaotic-DFT sequence-based encryption in CP-OFDM system

Photonic Network Communications - Orthogonal frequency division multiplexing (OFDM) is considered as one of the most significant transmission methodologies of the recent past. Moreover, it permits...     

Studies of the trimethylsilyl derivatives of unhydrated cement and hydrated cement pastes by fourier transform infrared spectroscopy

Trimethylsilyl derivatives (T-derivatives) of unhydrated cement and hydrated cement pastes were studied by Fourier transform infrared spectroscopy. The infrared spectra of all these derivatives are very similar. However, when the spectrum of the T-derivatives of the unhydrated cement is subtracted from those of the hydrated pastes, a difference in the characteristics of the siloxane bands is observed in the subtracted spectra. The implications of these observed changes to cement hydration process is discussed.     

Enhanced visible photoluminescence in ZnO quantum dots by promotion of oxygen vacancy formation

We report on the synthesis of ZnO quantum dots (QDs) rich in oxygen vacancies by inducing an oxygen deficient environment. The precise tunability of particle size is achieved by counter ion capping of the precursor used for synthesis. The prepared QDs show size tunable visible emission with high quantum yield.     

A GENERALIZED PERTURBATION APPROACH TO THE ANALYSIS OF MASS TRANSFER WITH CHEMICAL REACTION

A generalized perturbation approach is presented for the analysis of the simultaneous absorption of two gases in a liquid accompanied by a chemical reaction. The main objective is to derive approximate analytical solutions for the enhancement factors of the solute gases, for all reaction rates. The method consists of constructing a regular perturbation solution for slow reaction, whose convergence is accelerated by means of an Euler transformation, thereby extending its range of utility for larger reaction rates. Convergence is further improved by suppressing the leading singularity of the Euler-transformed series. The accelerated solution is found to predict the enhancement factors very accurately in the slow, intermediate and fast reaction regimes, and in particular, approach the boundary layer limit associated with fast reaction.