Setting the absolute threshold of vision

The performance of sensory systems in many cases is limited by the physical nature of the stimulus. For vision, the quantal nature of light limits detection by dark-adapted observers; only now are we beginning to be aware of the subtleties in the biophysical mechanisms underlying this exquisite sensitivity

Fostering Production of Pharmaceutical Products in Developing Countries

The ways in which pharmaceutical products are currently developed, manufactured, and distributed fail to meet the needs of developing countries. The recent emergence of new infectious diseases, the associated surge of healthcare nationalism, and the prevalence of substandard and falsified drugs have strengthened substantially the net benefits of augmenting the capacity of developing countries to produce such products locally. Most previous efforts to do so have foundered. The chance of success in the future would be maximized by the adoption of five strategies : (a) clarifying the zones of discretion created by the relevant treaties to ensure that local firms have the freedom to operate; (b) the use of “production triangles” (collaborations among developing-country governments, local firms, and developed-country pharmaceutical firms) to reduce regulatory impediments and to ensure that there exist adequate markets for locally produced products; (c) developing the human capital base in developing countries through initiatives such as an international apprenticeship system; (d) strengthening the legal and administrative apparatus for preventing the dissemination in developing countries of substandard and falsified drugs; and (e) reliance on regional economic communities to create economies of scale and to ensure that medicines are made available to all residents of all developing countries, while also stimulating competition among local firms. These strategies would both save many lives and strengthen the economic and social development of developing and least-developed countries

Molten Salt Thermal Energy Storage Systems

The feasibility of storing thermal energy at temperatures of 450 C to 535 C in the form of latent heat of fusion was examined for over 30 inorganic salts and salt mixtures. Alkali carbonate mixtures were chosen as phase-change storage materials in this temperature range because of their relatively high storage capacity and thermal conductivity, moderate cost, low volumetric expansion upon melting, low corrosivity, and good chemical stability. Means of improving heat conduction through the solid salt were explored

Helicopter gearbox bearing fault detection using separation techniques and envelope analysis

The main gearbox (MGB) is a crucial part of a helicopter. MGB bearings suffer intensively from stress and friction during flights hence concerns for their health condition and detecting potential defects become critical for the sake of operation safety and system reliability. In this study, bearing defects were seeded in the second epicyclic stage bearing of a commercial Class A helicopter MGB. Vibration and tachometer signals were recorded simultaneously for the purpose of fault diagnosis. The tests were carried out at different power and speed conditions for various seeded bearing defects. This paper presents a comparison of signal processing techniques employed to identify the presence of the defects masked by strong background noise generated from an operation helicopter MGB

Ferromagnetism in Fe-substituted spinel semiconductor ZnGa2_2O4_4

Motivated by the recent experimental observation of long range ferromagnetic order at a relatively high temperature of 200K in the Fe-doped ZnGa$_2$O$_4$ semiconducting spinel, we propose a possible mechanism for the observed ferromagnetism in this system. We show, supported by band structure calculations, how a model similar to the double exchange model can be written down for this system and calculate the ground state phase diagram for the two cases where Fe is doped either at the tetrahedral position or at the octahedral position. We find that in both cases such a model can account for a stable ferromagnetic phase in a wide range of parameter space. We also argue that in the limit of high Fe$^{2+}$ concentration at the tetrahedral positions a description in terms of a two band model is essential. The two $e_g$ orbitals and the hopping between them play a crucial role in stabilizing the ferromagnetic phase in this limit. The case when Fe is doped simultaneously at both the tetrahedral and the octahedral position is also discussed.Comment: 10 pages, 9 figures, added text, J. Phys. Cond. Mat. (to appear

Data Quality Assessment Using a Sliding Window Cumulative Sum Control Chart

2012 S.C. Water Resources Conference - Exploring Opportunities for Collaborative Water Research, Policy and Managemen

Improvement and Optimization of Performance of Iron Ore Beneficiation Plant

JSW steel in an integrated steel plant of 2.5 Mtpa crude steel capacity and is being expanded to 10 Mtpa in phases. The plant facilities include 3 Mt Iron Ore Beneficiation Plant, 4.2 Mt Pellet Plant, 1.6 Mt Corex iron making, 0.9 Mt Blast Furnace, 2.5 Mt BOF — CCP and 2 Mt Hot Strip Mill. In order to control alumina in iron ore fines, the iron ore beneficiation plant was installed based on in-house developed process. During its operation of last two years, number of improvements and innovations have been introdu-ced to improve the reduction in alumina, improve yield and reduce moisture of concentrate

Development of Beneficiation Process for High Alumina Iron Ores of Bellary-Hospet Region

JSW Steel is operating a 4.2 Mtpa capacity Pellet Plant to produce iron oxide pellets from the iron ore fines avail-able in the surrounding Bellary-Hospet region of southern India. Iron ore fines which get generated during mining are soft and rich in alumina with high amount of ultra fines. These characteristics of iron ore fines make it difficult to produce good grade pellets for use in COREX iron making units. Apart from this, high alumina in the pellets increases the slag volume in Corex, which demands additional heat energy, resulting in increased fuel rate. Hence, it was decided to set up a beneficiation plant to reduce the alumina content of the ore fines. Iron ore fines from several sources available in the Bellary- Hospet region were evaluated for their suitability for beneficiation as each source differs in chemistry, particle size distribution and washability characteris-tics. A technique called "Sizewise Washability Technique" was developed to study the washability characteristics of the ore fines to determine the extent of alumina reduction on washing and corresponding yield of concentrate. Iron ore fines from 13 sources were tested and were classified as Preferable, Tolerable and Not- Washable depending on their suitability for beneficiation. Mineralogical studies were also undertaken to understand the liberation characterist-ics of gangue minerals to achieve proper alumina reduction during beneficiation