Application of hydrocyclones for recovery of fine gold from placer material

Alaska and other gold areas have seen a sharp resurgence of placer mining in the last few years. Mines using sluice boxes usually recover gold down to 100 mesh, but recovery of gold finer than this size is a function of particle shape factor, sluice box design and operating parameters. It is felt that a concentrating device is needed to recover gold finer than 100 mesh that may not be recoverable in a sluice box. The device should be capable of processing a large volume of water and solids discharged from the sluice-box. Compound water cyclones, successfully used in the coal processing industry, seem to offer solutions. A system using these devices could recover a concentrate which would be one twenty fifth the size of the original solids in a two stage process. It is not intended to produce a finished product with cyclones, but to reduce bulk so that the reduced concentrate, free of slimes, could further be treated by flotation, gravity methods, or cyanidation to isolate the gold. This report addresses only the application of hydrocyclones for concentrating gold from placer material.Submitted to Mining and Mineral Resources Research Institute, Office of Surface Mining, U.S. Department of Interior, Washington, D.C. Grant No. G519400

A Comparative Study: Change Detection and Querying Dynamic XML Documents

The efficient management of the dynamic XML documents is a complex area of research. The changes and size of the XML documents throughout its lifetime are limitless. Change detection is an important part of version management to identify difference between successive versions of a document. Document content is continuously evolving. Users wanted to be able to query previous versions, query changes in documents, as well as to retrieve a particular document version efficiently. In this paper we provide comprehensive comparative analysis of various control schemes for change detection and querying dynamic XML documents

Studies on morphometry and hydrology of Gandhisagar Reservoir with special reference to its fisheries

Gandhisagar, the second largest reservoir of India is located in Mandsaur district of Madhya Pradesh at latitude 24°44'N and longitude 75°33'E at an altitude of 403.56m MSL in orientation from NE to SE. It has an extensive water spread area of 66000 ha at full reservoir level with a maximum and mean depth of 49.52 and 11.73 m respectively. The maximum length and width of the reservoir are 112 and 16km having a total shore line of 442km. Details of catchment area, bathymetry, standard hydrological data giving water level relation of the basin to water spread area, volume and fish production and the bottom topographical details of 11 experimental fishing stations and 6 fish landing centres are discussed

The local power of the gradient test

The asymptotic expansion of the distribution of the gradient test statistic is derived for a composite hypothesis under a sequence of Pitman alternative hypotheses converging to the null hypothesis at rate $n^{-1/2}$, $n$ being the sample size. Comparisons of the local powers of the gradient, likelihood ratio, Wald and score tests reveal no uniform superiority property. The power performance of all four criteria in one-parameter exponential family is examined.Comment: To appear in the Annals of the Institute of Statistical Mathematics, this http://www.ism.ac.jp/editsec/aism-e.htm

Influence of different storage temperatures and packing material in extending shelf life and quality attributes of palmyrah (Borassus flabellifer L.) neera

Palmyrah neera (inflorescence sap) is susceptible to natural fermentation at ambient temperature within a few hours of extraction due to enzymatic and microbial activity. Once fermented, neera becomes toddy which is unsuitable as a health drink or as a value-added product. Therefore, a study was carried out to investigate the influence of different packing materials and storage conditions on the shelf life and to keep the quality of palmyrah neera. The experiment was conducted in a completely randomised factorial design with two factors at unequal levels replicated thrice. HDPE 50 micron pouch (P1), PET bottle (P2) and glass bottle (P3) and cold storage at 2 oC (S1), cold storage at 4 oC (S2) and refrigerated storage (8-10 oC) (S3) were the packing material and storage conditions respectively used during experimentation. Physio-chemical properties viz., total soluble solids, pH and reducing sugars showed an increasing trend up to the 4th week of storage. At the same time, phenols, titrable acidity and alcohol content increased up to the 6th week of storage. Maximum total soluble solids (10.80 oBrix), reducing sugars (5.76%), minimum phenolic content (0.323 mg) and titrable acidity (1.116%) were recorded when palmyrah neera was packed in HDPE 50 micron pouch, whereas the maximum total soluble solids (10.83oBrix), reducing sugars (5.75%), minimum phenolic content (0.322 mg) and titrable acidity (1.14%) were recorded when palmyrah neera was stored at 2 oC. Among the different packing material and storage conditions, HDPE 50 micron and storage at 2 oC was effective in extending the shelf life and quality attributes of palmyrah neera

A spherical perfect lens

It has been recently proved that a slab of negative refractive index material acts as a perfect lens in that it makes accessible the sub-wavelength image information contained in the evanescent modes of a source. Here we elaborate on perfect lens solutions to spherical shells of negative refractive material where magnification of the near-field images becomes possible. The negative refractive materials then need to be spatially dispersive with $\epsilon(r) \sim 1/r$ and $\mu(r)\sim 1/r$. We concentrate on lens-like solutions for the extreme near-field limit. Then the conditions for the TM and TE polarized modes become independent of $\mu$ and $\epsilon$ respectively.Comment: Revtex4, 9 pages, 2 figures (eps

Amplification of evanescent waves in a lossy left-handed material slab

We carry out finite-difference time-domain (FDTD) simulations, with a specially-designed boundary condition, on pure evanescent waves interacting with a lossy left-handed material (LHM) slab. Our results provide the first full-wave numerical evidence for the amplification of evanescent waves inside a LHM slab of finite absorption. The amplification is due to the interactions between the evanescent waves and the coupled surface polaritons at the two surfaces of the LHM slab and the physical process can be described by a simple model.Comment: 4 pages, 2 figure

Observation of the Smectic C -- Smectic I Critical Point

We report the first observation of the smectic C--smectic I (C--I) critical point by Xray diffraction studies on a binary system. This is in confirmity with the theoretical idea of Nelson and Halperin that coupling to the molecular tilt should induce hexatic order even in the C phase and as such both C and I (a tilted hexatic phase) should have the same symmetry. The results provide evidence in support of the recent theory of Defontaines and Prost proposing a new universality class for critical points in layered systems.Comment: 9 pages Latex and 5 postscript figures available from [email protected] on request, Phys.Rev.Lett. (in press

Scintillation Counters for the D0 Muon Upgrade

We present the results of an upgrade to the D0 muon system. Scintillating counters have been added to the existing central D0 muon system to provide rejection for cosmic ray muons and out-of-time background, and to provide additional fast timing information for muons in an upgraded Tevatron. Performance and results from the 1994-1996 Tevatron run are presented.Comment: 30 pages, 25 postscript figure