James J. Sharp

Methodologies for Problem Solving: An Engineering Approach.

Abstract Learning how to approach and solve problems which relate to real world situations is an integral part of the education of many higher and further education students and is particularly relevant to students studying for a professional or vocational degree. This paper outlines the nature of problems experienced by engineers and indicates how engineering students are taught to approach the identification and solution of the types of problems which they will experience as practicing professionals. Methodologies used are of general interest and may be applicable in other, unrelated, disciplines.

Treatment of fuel peat to enhance moisture removal

Abstract Dewatering of peat by mechanical pressing can be greatly improved by treatments, such as addition of electrolytes and freezing and thawing, which break down the colloidal peat structure. Particularly, by addition of 9.4% lime to peat, followed by freezing, thawing and pressing at ≈8.27 MPa, the moisture content can be reduced from 90% to ≈50%. The improvement gained is commercially advantagous.

The use of labyrinth weirs for water level control

ABSTRACT Labyrinth weirs have particular advantages for water level control in flat land. At low flows intake structures require a certain minimum depth but the maximum depth at high flows must be limited to prevent extensive upstream flooding. Typically this is achieved using a low weir surmounted by a controllable undershot gate that is closed at low flows and opened as the flow increases. A labyrinth weir is an attractive alternative that fulfils the same purpose. In this structure the crest length is made significantly longer than the width of the river; this is achieved by having a planform that consists of repeating geometric cycles, typically trapezoidal in form. The long crest length means that it can pass large flows at low heads. Water levels at low flows are maintained simply by the height of the weir crest. The economic advantages of labyrinth weirs are demonstrated with respect to a weir constructed on the Ciwadas River in Indonesia. This was designed to handle flood flows of 200 m3/s and to ...

A Note on Energy Dissipation

The dissipation of energy in a stilling basin is often increased by the use of blocks and baffles which create additional eddies and turbulence in the flow. These are beneficial in decreasing the specific energy of the flow and in lowering depths downstream of the hydraulic jump. However it must be appreciated, by students and teachers alike, that dissipation of additional energy will increase downstream velocities. Although this should be obvious from a specific energy diagram the effects may easily be overlooked. This brief paper helps to clarify the extent of the velocity increase and provides quantitative data showing the relationship between velocity increase and specific energy decrease.

Dimensional Analysis of Synovial Joints

Prior to undertaking experiments or developing a mathematical model of a complex phenomenon it is necessary to do some preliminary work in an attempt to gain some understanding of the physics involved and to identify the relevant parameters. Although usually thought of as a tool for physical modelling, dimensional analysis really provides a basic framework for thinking about a problem and this is useful whether the end result is intended to be a physical or a mathematical model. Students of complex systems would thus be well advised to begin with a partial analysis with the intention of obtaining some fundamental understanding of the phenomenon under consideration. Identification of the variables involved leads to the development of functional equations and a set, or sets, of dimensionless parameters. These parameters provide the modeller with a guide to the parameters which might appear, separately or in combination, in any complete solution. In many cases, a complex system may be usefully broken down into a number of subsystems each of which may be treated separately, but with the outputs from some subsystems (the dependent parameters) being the inputs (the independent parameters) to other subsystems or to the main system. The example given here refers to a study of joints of the human body where dimensional analysis was used as a preliminary tool in a larger investigation designed to lead eventually to a finite element model. The paper attempts to show how such an analysis can be helpful: (1) in thinking about the problem; (2) in identifying the dimensionless parameters which provide a potential framework for a more complete solution; and (3) in breaking down a very complex problem into a number of related subsystems which can be more easily solved.

Mixing Tubes for Improving Dilution at Small Outfalls

The effects of pre-dilution devices and mixing tubes on overall initial dilution between discharge point and surface are considered. A novel shape of tube is studied in which the three dimensional jet is converted to a two dimensional flow through a slot at the end of the mixing tube. This is shown experimentally to be generally similar but perhaps slightly better than traditional cylindrical mixing tubes.

Reply: Hydrotechnical studies of Peter's River

The authors agree with Dr. Russell and thank him for his comments. His method and computer program were used by the authors in an earlier conference paper dealing with the same subject (Lye and Sharp 1993). There the 1983 flood was first considered to be the highest in the last 100 years and then the highest in the last 50 years. The underlying flood distribution was assumed to be lognormal and the uncertainty in the parameters of the distribution was estimated using the recorded flows. Dr. Russell has used a slightly different approach. His analysis assumed the Gumbel distribution as

Treatment of fuel peat by the addition of lime with a freeze-thaw cycle

Abstract Dewatering of fuel peat by mechanical pressing can be greatly improved by treating the peat with lime and then running it through a freeze-thaw cycle. Results are presented for different concentrations of lime and different types of treatment.