A Custom VLSI Chip Set for Digital Signal Processing in High-Speed Voiceband Modems

Systems modems intended for use in relatively large private networks are characterized by high performance, reliability and flexibility to support network management, and multiple modes of operation and user features. This paper describes a programmable digital signal processor which is teamed with a 16-bit microprocessor in a dual processor architecture satisfying the requirements of high-speed voiceband systems modems. The architecture of the two custom integrated circuits which form the basis of the signal processor is presented. This processor has novel arithmetic, data structure address generation, and program flow-control capabilities, which result in a high utilization of the arithmetic unit and a low program overhead for housekeeping tasks. Some of these features are illustrated by programming examples.     

Comparison of chlorination and chloramination practices on microbial inactivation efficiencies within a scaled‐up water distribution network using central composite design

Disinfection practices reduce the incidence of water‐borne diseases but may result in formation of disinfection byproducts (DBPs) in raw water that are reported to be carcinogenic. Central composite design (CCD) was employed in the present study for optimization of disinfectant dose and contact time with the rationale to evaluate if an optimal balance could be achieved between minimal DBPs formation and effective microbial inactivation with either free or combined chlorine in treated water within a lab‐scale prototype network to simulate real water distribution network conditions. After a series of experimental runs based upon design of experiments (DoE) by CCD, dose was found to be the most significant factor (P < 0.01) in determining DBPs formation in both disinfectant’s applications. Where, contact time significantly (P < 0.01) affected bacterial inactivation in chlorination experiments, in contrast, dose was effective in chloramination experiments. Thus, it was concluded that the optimal balance may be achieved in the water networks with the help of multifactorial optimization when disinfectant dose was maintained near 3 mg/L as applied chlorine dose in both disinfection cases, while contact time was 62 and 155 min for chlorine and chloramine, respectively.     

Kinetic study of crude oil-to-chemicals via steam-enhanced catalytic cracking in a fixed-bed reactor

This study presents new experimental results on the direct conversion of crude oil to chemicals via steam-enhanced catalytic cracking. We have organized the experimental results with a kinetics model using crude oil and steam co-feed in a fixed-bed flow reactor at reaction temperatures of 625, 650, and 675°C over the Ce-Fe/ZSM-5 catalyst. The model let us find optimum conditions for crude oil conversion, and the order of the steam cracking reaction was 2.0 for heavy oil fractions and 1.0 for light oil fractions. The estimated activation energies for the steam cracking reactions ranged between 20 and 200 kJ/mol. Interestingly, the results from kinetic modelling helped in identifying a maximum yield of light olefins at an optimized residence time in the reactor at each temperature level. An equal propylene and ethylene yield was observed between 650 and 670°C, indicating a transition from dominating catalytic cracking at a lower temperature to a dominating thermal cracking at a higher temperature. The results illustrate that steam-enhanced catalytic cracking can be utilized to effectively convert crude oil into basic chemicals (52.1% C2-C4 light olefins and naphtha) at a moderate severity (650°C) as compared to the conventional high-temperature steam cracking process.     

Spectral and kinetic characterization of orange-red emitting Sr3Al2O6:Eu/Smphosphor

We report, for the first time Sm³⁺ doped nanocrystalline Sr₃Al₂O₆ phosphor. Effect of Eu³⁺ doping in the present host is also studied. XRD results match with standard data from JCPDS file confirming cubic structure with Pa3 space group. PL Maximum for Eu/Sm is obtained at 590 nm and 573 nm respectively, and corresponds to orange-red region of electromagnetic spectrum. Morphology of combustion synthesized powder is platelet, while for calcined powders, cubic shaped crystallites are obtained. Information on various trapping parameters is obtained from thermally stimulated Luminescence (TSL) studies. Non-shifting T_m property is applied to define the order of kinetics and is thereafter assumed as 1. T_m − T_stop procedure and repeated initial rise method are applied to estimate apparent activation energies and peak positions. Further, chi-square minimization procedures via computerized glow curve deconvolution (CGCD) technique provide best-fit results. The figure of merit for deconvoluted Eu and Sm doped samples are 0.48% and 0.67% respectively. The apparent activation energies for Eu doped samples are 0.89 eV, 1.05 eV, 1.30 eV, while, for Sm doped samples, the activation energies are 0.84 eV and 1.06 eV. Persistence behavior of the present phosphor is attributed to contribution due to shorter and longer components as are obtained during phosphorescence decay studies. In both the cases; probability of recombination is more in comparison to the retrapping within a quasi continuous framework of trapping sites.     

Numerical treatment of nonlinear Emden–Fowler equation using stochastic technique

The article is based on the approximate solution of a well known Lane–Emden–Fowler (LEF) equation. A trial solution of the model is formulated as an artificial feed-forward neural network containing unknown weights which are optimized in an unsupervised way. The proposed scheme is tested successfully on various test cases of initial value problems of LEF equations. The reliability and effectiveness is validated through comprehensive statistical analysis.     

Project Oriented Problem Based Learning: A Wireless Sensor Network Perspective

Every nation rely on latest engineering technologies to foster in today’s technological era. Wireless Sensor Networks (WSNs) is one of the latest emerging technologies being the center of interest of today’s researchers. All the researchers work hard to produce quick deliverables through Research and Development (RandD) and by applying different learning pedagogues. Currently, the learning pedagogues in Engineering RandD are Project Based Learning and Problem Based Learning (PBL). Based on these pedagogues, this paper propose and implements a hybrid pedagogy called Project Oriented PBL (PO-PBL) which is time effective and result oriented learning pedagogy. It has resulted in providing impetus to RandD in WSNs. Further the proposed pedagogy is divided into two paradigms namely PO-PBL Macro Model and PO-PBL Micro Model. We observed that PO-PBL Macro Model results in optimal number of deliverables in time restricted manner over large scale. Moreover, we have also implemented PO-PBL Micro Model, compared it with PO-PBL Macro Model and propose PO-PBL Micro Model as basis for designing self-learning algorithm for WSNs devices.     

Prediction of Evaporation Losses in Wet Cooling Towers

The accurate prediction of all aspects of cooling tower behavior is very important. Accurately predicting evaporation losses is significant because water in cooling towers is cooled primarily through the evaporation of a portion of the circulating water, which causes the concentration of dissolved solids and other impurities to increase. An empirical relation is developed on the basis of ASHRAE's rule of thumb that is simple and accurate with a wide range of applicability. The predicted values are in good agreement with experimental data as well as predictions made by an accurate mathematical model.