More readings from One man's wilderness : the journals of Richard L. Proenneke, 1974-1980 /

Includes index.

Revue de Bretagne

Title varies: 1857-1888, Revue de Bretagne et de Vendée; 1899-1901, Revue de Bretagne, de Vendée & d'Anjou

Vuelo de cisnes : díptico pasional /

Series name on front cover: Obras Completas; also printed at head of on front end paper; titles in series printed on both pasted-down endpapers.

Biographical memoirs /

List of papers contained in v. 1-9 is given in National Academy of Sciences. Proceedings... Index... 1915-24, 1926.

Mémoires de la Société nationale des antiquaires de France.

Also numbered in series of 10 vols. each; v. 31- called sér. 4, v. 1-

Annual Report of the Board of Commissioners of Public Charities

Found Also In Series of Public Documents

Biblioteca storica del risorgimento italiano.

Numbered in series of 12 numbers each.

Madjalah ilmu alam untuk Indonesia. Indonesian journal for natural science

Volumes 4-66 also numbered in series

DHEW health research principles /

Contains conference report from the National Conference on Health Research Principles held October 3 and 4, 1978 at the National Institutes of Health.

Oriens Christianus.

Editor: 19 A. Baumstark.

Mathematical modelling

The development of a new process model of cement grinding in two-stage mills is discussed. The new model has been used to simulate cement grinding and predicting mill performance in open and closed circuit configuration. The new model considered the two-compartment mill as perfectly mixed slices in series. The breakage rate function uses the back calculation technique to determine offline using drop weight and abrasion tests.

Cascaded DC-DC converter connection of photovoltaic modules

New residential scale photovoltaic (PV) arrays are commonly connected to the grid by a single dc-ac inverter connected to a series string of pv panels, or many small dc-ac inverters which connect one or two panels directly to the ac grid. This paper proposes an alternative topology of nonisolated per-panel dc-dc converters connected in series to create a high voltage string connected to a simplified dc-ac inverter. This offers the advantages of a converter-per-panel approach without the cost or efficiency penalties of individual dc-ac grid connected inverters. Buck, boost, buck-boost, and Cuk converters are considered as possible dc-dc converters that can be cascaded. Matlab simulations are used to compare the efficiency of each topology as well as evaluating the benefits of increasing cost and complexity. The buck and then boost converters are shown to be the most efficient topologies for a given cost, with the buck best suited for long strings and the boost for short strings. While flexible in voltage ranges, buck-boost, and Cuk converters are always at an efficiency or alternatively cost disadvantage.

A theoretical exploration of catchment-scale sediment delivery

This paper proposes a theoretical explanation of the variations of the sediment delivery ratio (SDR) versus catchment area relationships and the complex patterns in the behavior of sediment transfer processes at catchment scale. Taking into account the effects of erosion source types, deposition, and hydrological controls, we propose a simple conceptual model that consists of two linear stores arranged in series: a hillslope store that addresses transport to the nearest streams and a channel store that addresses sediment routing in the channel network. The model identifies four dimensionless scaling factors, which enable us to analyze a variety of effects on SDR estimation, including (1) interacting processes of erosion sources and deposition, (2) different temporal averaging windows, and (3) catchment runoff response. We show that the interactions between storm duration and hillslope/channel travel times are the major controls of peak-value-based sediment delivery and its spatial variations. The interplay between depositional timescales and the travel/residence times determines the spatial variations of total-volume-based SDR. In practical terms this parsimonious, minimal complexity model could provide a sound physical basis for diagnosing catchment to catchment variability of sediment transport if the proposed scaling factors can be quantified using climatic and catchment properties.

Modelling sediment delivery ratio over the Murray Darling Basin

This paper presents a scientific and technical description of the modelling framework and the main results of modelling the long-term average sediment delivery at hillslope to medium-scale catchments over the entire Murray Darling Basin (MDB). A theoretical development that relates long-term averaged sediment delivery to the statistics of rainfall and catchment parameters is presented. The derived flood frequency approach was adapted to investigate the problem of regionalization of the sediment delivery ratio (SDR) across the Basin. SDR, a measure of catchment response to the upland erosion rate, was modeled by two lumped linear stores arranged in series: hillslope transport to the nearest streams and flow routing in the channel network. The theory shows that the ratio of catchment sediment residence time (SRT) to average effective rainfall duration is the most important control in the sediment delivery processes. In this study, catchment SRTs were estimated using travel time for overland flow multiplied by an enlargement factor which is a function of particle size. Rainfall intensity and effective duration statistics were regionalized by using long-term measurements from 195 pluviograph sites within and around the Basin. Finally, the model was implemented across the MDB by using spatially distributed soil, vegetation, topographical and land use properties under Geographic Information System (GIs) environment. The results predict strong variations in SDR from close to 0 in floodplains to 70% in the eastern uplands of the Basin. (c) 2005 Elsevier Ltd. All rights reserved.

Two way power flow using GTO thyristors

Two-way power flow is nothing new and has been in practical use using line commutated converters for at least 50 years. With these types of converters, reversal of power flow can be achieved by increasing the firing angle of the devices beyond 90 degrees thus producing a negative DC voltage. Line commutated converters have several known disadvantages including: the direct current cannot be reversed, the power factor decreases when the firing angle increases and the harmonics are high on the line current. To tackle the above problems a forced commutated converter can be used. The power factor can be unity and the harmonics can be reduced. Many researchers have used PWM with different control techniques to serve the above purposes. In each converter arm, they used a forced commutated device with an antiparallel diode. Under the rectification mode of operation the current path is preponderantly through the diodes and under the inverter operation the current flows preponderantly through the forced commutated devices. Although their results were encouraging and gave a unity power factor with nearly sinusoidal current, the main disadvantage was that there were difficulties in controlling the power factor when the system is needed to operate at lagging or leading power factor. In this work, a new idea was introduced by connecting two GTOs antiparallel instead of a diode and a GTO. A single phase system using two GTO converters which are connected in series was built. One converter operates as a rectifier and the other converter operates as an inverter. In the case of the inversion mode and in each inverter arm one GTO is operated as a diode simply by switching it always on and the other antiparallel GTO is operated as a normal device to carry the inverter current. In case of the rectification mode, in each arm one GTO is always off and the other GTP is operated as a controlled device. The main advantage is that the system can be operated at lagging or leading power factor.