Solvent extraction separation of titanium(IV), vanadium(V) and iron(III) from simulated waste chloride liquors of titanium minerals processing industry by the trialkylphosphine oxide Cyanex 923

The solvent extraction of magnesium(II), aluminium(III), titanium(IV), vanadium(V), chromium(III), manganese(II) and iron(III) from hydrochloric acid solutions has been investigated using the trialkylphosphine oxide Cyanex 923 (TRPO) in kerosene as extractant. The results demonstrate that titanium(IV), vanadium(V) and iron(III) are extracted into kerosene as TiOCl₂·2TRPO, VO₂Cl·TRPO and HFeCl₄·2TRPO, respectively. On the other hand magnesium(II), aluminium(III), chromium(III) and manganese(II) are not extracted with TRPO from hydrochloric acid solutions (1.0–4.0 mol dm^?3) under the experimental conditions. IR spectral studies of the extracted complexes were further used to clarify the nature of the extracted complexes. The effect of the diluent on the extraction of titanium(IV), vanadium(V) and iron(III) has been studied and correlated with the dielectric constant. The loading capacity of the TRPO system has been evaluated and the potential for the separation and recovery of titanium(IV), vanadium(V) and iron(III) from simulated waste chloride liquors of the titanium minerals processing industry has been assessed. Copyright © 2004 Society of Chemical Industry     

A study of protean systems—Redundancy optimization in consecutive-k-out-of-n:F systems

A Protean system is a system that is subject to changes from time to time. A consecutive-k-out-of-n:F system that has a fluctuation of demand on the system performance, may be classed under Protean systems. The changing demand may be handled by improving the system performance using some extra resources. In this paper, the extra resources considered are in the form of i.i.d. components. These components are allocated with the objective of maximising the system reliability. There are three methods developed in this paper. The first method is developed by formulating the problem mathematically. The second method involves enumeration of all possible allocations of a given number of i.i.d. components. The third method is a heuristic, based on component reliability importance. The accuracy of the heuristic is established by comparing it with the second method. These two methods are compared using computer programs developed by one of the authors.     

A novel quad source/drain metal nanocrystal memory device for multibit-per-cell storage

Based on the 2-bit-per-cell metal nanocrystal memories, a novel quad source/drain device capable of 4 bits per cell data storage is demonstrated. Along with the new device structure, a reliable parallel read scheme with low V/sub DS/ is also proposed and verified for 4-bit-per-cell operations. The proposed read scheme requires 1.125 read operations on average to read out the 4 bits stored in a cell, while minimizing the read disturb and interference between the different storage bits.     

Design of serial concatenated MSK schemes based on density evolution

We consider the design of convolutional codes and low density parity check (LDPC) codes with minimum-shift keying (MSK) when the receiver employs iterative decoding and demodulation. The main idea proposed is the design of coded schemes that are well matched to the iterative decoding algorithm being used rather than to hypothetical maximum-likelihood decoding. We first show that the design is crucially dependent on whether the continuous phase encoder (CPE) is realized in recursive form or in nonrecursive form. We then consider the design of convolutionally coded systems and low density parity check codes with MSK to obtain near-capacity performance. With convolutional codes, we show that it is possible to improve the performance significantly by using a mixture of recursive and nonrecursive realizations for the CPE. For low density parity check codes, we show that codes designed for binary phase shift keying are optimal for MSK only if the nonrecursive realization is used; for the recursive realization, we design new LDPC codes based on the concept of density evolution. We show that these codes outperform the best known codes for MSK and have lower decoding complexity.     

Upper and Lower Bounds for Selection on the Mesh

A distance-optimal algorithm for selection on the mesh has proved to be elusive, although distance-optimal algorithms for the related problems of routing and sorting have recently been discovered. In this paper we explain, using the notion of adaptiveness, why techniques used in the currently best selection algorithms cannot lead to a distance-optimal algorithm. For worst-case inputs we apply new techniques to improve the previous best upper bound of 1.22n of Kaklamanis et al. [7] to 1.15n . This improvement is obtained in part by increasing the adaptiveness of previous algorithms. Received May 25, 1995; revised June 1, 1996.     

Band-rejection fibre filter using periodic core deformation

Grating-based all-fibre bandstop filters were fabricated by introducing periodic deformations in the core of the fibre with a CO₂ laser by first ablating the surface of the fibre and then annealing it. These devices, which can be tailored to any wavelength, have a broad bandwidth (10 nm), high peak wavelength rejection (>20 dB), low insertion loss (<0.3 dB), a very flat response outside the rejection band, and a short physical length (6 mm)     

Millimeter wave backscatter measurements in support of collision avoidance applications

Millimeter-wave short range radar systems have unique advantages in surface navigation applications, such as military vehicle mobility, aircraft landing assistance, and automotive collision avoidance. In collision avoidance applications, characterization of clutter due to terrain and roadside objects is necessary in order to maximize the signal-to-clutter ratio (SCR) and to minimize false alarms. The results of two types of radar cross section (RCS) measurements at 95 GHz are reported in this paper. The first set of measurements presents data on the normalized RCS (NRCS) as well as clutter distributions of various terrain types at low grazing angles of 5° and 7.5°. The second set of measurements presents RCS data and statistics on various types of roadside objects, such as metallic and wooden sign posts. These results are expected to be useful for designers of short-range millimeter-wave collision avoidance radar systems.     

ITU-T standardization of audiovisual communication systems in ATMand LAN environments

This paper presents the ITU-T Study Group 15 development of H-series Recommendations that allow interworking between different audiovisual communication terminals manufactured by different equipment providers. The paper focuses on H.310 and H.321 systems for broad-band ATM environments and H.322 and H.323 systems for LAN environments where the quality of service may or may not be guaranteed. The paper first lists the Recommendations developed by the ITU-T for audiovisual communication systems and the network environments in which they may be used. It then describes the design philosophy, the network specific characteristics, and hardware trials for each system. Then it describes the communication control protocol defined in H.245 which is used commonly by different audiovisual communication systems. Finally, the paper discusses interworking scenarios for communication between the different types of terminal on different networks