bluuebunny/crossref_metadata_2025_split huggingface dataset:
Rotodynamic Pump Efficiency Variations Due to Changes of Operating Speed or Temperature
Authors: Neumann B 
Published: February 2007

The same pump is often required to operate at speeds and temperatures different from those at which it was tested by the manufacturer. This can be and is frequently done with appropriate design measures taken to meet the most stringent operating conditions dictated by the highest operating speed and temperature. In other cases testing of the unit at its design speed (or temperature) may be impractical and too costly to he justified. In all cases a prediction of the unit's performance at its full operating conditions is important, particularly for high-power, large or high-speed machines. Theoretical considerations and test evidence show that changes of performance do take place at varying speed and temperature. These changes are due mainly to the variation of the flow Reynolds number. However, a reliable method of quantifying these changes has been and still is a matter of controversy. A large number of formulae has been published by different authors in an effort to establish a general rule of efficiency ‘scaling’ for all hydraulic machines. Initially all losses of the machine were considered; it was found later that certain types of losses (kinetic) should not be ‘scaled’. However, in all cases, it is still expected that the higher the increment of speed (or temperature) in relation to test, the higher the efficiency improvement for all hydraulic machines. The present work suggests that each category of energy loss behaves in a different fashion at increased speed or temperature. Therefore, whereas some losses remain constant at all speeds, other losses vary at different rates with Reynolds number. For this reason it follows that, in certain circumstances, an ‘optimum’ speed ratio or temperature ratio may exist at which efficiency increment would become a maximum. Two expressions describing such an optimum speed ratio and temperature ratio in terms of the loss breakdown of the pump are developed and discussed. An analysis of the expressions shows that, in certain circumstances, which may easily occur in practice, a loss of efficiency rather than an increment can occur with increased speed (or temperature). Moreover, since disc friction and volumetric losses exert a major influence on the magnitude and the position of the optimums, the individual unit breakdown of losses in test conditions is required to make a reliable performance prediction for speeds (or temperatures) different from test speeds (or temperatures).
A Study on an Improved Direct Search Interpolation Method for Two-Axis CNC Thermal Cutting Systems
Authors: Lho T-J , Na S-J 
Published: February 2007

A microcomputer-based reference pulse software interpolator, which can be effectively applied for two-axis computer numerical control (CNC) systems such as those used in plasma arc cutting and laser beam cutting machines, is proposed in the present study. The proposed interpolation method is based upon searching in two or three directions for the minimum path error, while the axes of motion do not move simultaneously in the stairs approximation method and the basis for selecting an interpolating point is not related to any criteria of path error in the digital differential analyses (DDA) method. Accordingly, this method has many advantages over the other two competing methods, such as small maximum path error of only a half basic length unit (BLU), uniform velocity along the cutter path, high degree of path smoothness and maximum velocity allowable. Since the velocity of the proposed CNC system is controlled through adjusting two interrupt interval times at each interpolation step, a constant velocity can be maintained along any cutting path. The proposed interpolation algorithm is very simple and can be easily applied for the practical CNC systems, since it is based on transforming the interpolating paths in all interpolating cases to those in one typical case.
A Study on Parameter Optimization With Numerical Heat Conduction Model For Circumferential Gas Tungsten Arc (GTA) Welding of Thin Pipes
Authors: Lho T-J , Na S-J 
Published: February 2007

One of the important problems to be solved in welding engineering is to develop a mathematical method for the determination of optimum process parameters. In order to estimate the optimal process parameters in circumferential gas tungsten arc (GTA) welding of thin pipes, an objective was chosen to maintain a uniform bead width over the full circumferential joint, while the constraints consist of the capacity limit of the welding power source and equipment used. A transient three-dimensional finite difference model (FDM) of the heat conduction flow in the circumferential GTA welding of pipes was adopted for calculating the temperature field considering the temperature-dependent thermal properties of the workpiece, and consequently for determining the resultant bead width in circumferential welding of the pipe workpiece. An efficient optimization model for the numerical heat conduction flow was proposed to evaluate the optimal welding current with a given welding velocity for a required bead width. Its solution was obtained by employing the steepest descent method (SDM), where the initial value of the welding current was estimated by using the linear complementary problem (LCP), and the welding currents in the middle part of the pipe were interpolated by the least-squares approximation method of the second order. The experimental results of the bead formation showed that the developed mathematical model can be effectively applied to obtain the optimal welding condition in circumferential welding of thin pipes, especially thin pipes with a small diameter and high thermal conductivity.
Supply Chain Dynamics—The Change Engineering Challenge of the Mid 1990s
Authors: Towill D R 
Published: February 2007

Much has been written concerning the supply chain demand amplification problem, best described by the ‘law of industrial dynamics’. Broadly speaking, if a supply chain can find a way to fluctuate, it will. The paper defines supply chains and reviews their current state of development. By way of a simulation example, the importance of good, shared, information flow is highlighted, as are several other strategies that lie more within the control of individual businesses. Good supply chain operation requires adequate design, led by a product champion committed to systems change. Persuasive evidence to support the product champion is therefore offered. Examples include internally generated demand amplification caused by human schedulers; an industrial supply chain case history; supply chain redesign via simulation; and a review of a proposed effectiveness framework which offers the possibility of integrating both modelling and design phases. The methodologies that are described herein may be universally applied to any industrial or commercial sector in which there is a value-added process. They have found great favour in the automotive industry, which is manifestly an area of endeavour where customer selectivity leads directly to the ‘demand chain’ viewpoint. However, a health care supply chain example also appears in the paper because it contains an important feature which could be duplicated to great advantage in many other applications. This is the opportunity taken to build customer-driven ‘phase advance’ or predictive capability into the system in order to improve the flow of both orders and products.
Developments in Two-Stroke Cycle Engine Exhaust Emissions
Authors: Kenny R G 
Published: February 2007

This paper is concerned with the exhaust emissions from two-stroke cycle spark ignition engines and the means being investigated to reduce them. The simple two-stroke engine has inherently low levels of NOx emissions and high levels of hydrocarbon emissions. The reasons for these emissions characteristics are explained by reference to the open literature. The two-stroke engine is used in a wide range of applications including low-cost, low-output mopeds and high-performance motorcycles. More recently there has been a resurgence of interest in the two-stroke as an alternative to the four-stroke engine for automotive use. A number of the recently reported approaches to emissions control are reviewed, including the use of exhaust oxidation catalysts in simple low-cost engines and direct fuel injection on more costly, multi-cylinder engines.
Monitoring of Gasoline Fuel Distribution in a Research Engine
Authors: Winklhofer E , Fraidl G K , Plimon A 
Published: February 2007

Fuel distribution in gasoline engines has significant influence on the cyclic stability of charge ignition and combustion, and hence on engine performance parameters related to the variation of combustion and heat release. There are numerous ways to influence in-cylinder fuel distribution by means of mixture preparation systems, engine aspiration or by combustion chamber geometry itself. However, methods to observe in-cylinder fuel distribution are scarce, and very often charge distribution—homogeneous or highly stratified—is just heuristically assessed, based on engine performance data. Therefore, a method has been devised which allows observation of vaporized fuel in the cylinders of optically accessed engines. The method, based on the absorption of infra-red laser light radiation by hydrocarbon molecules, needs optical access to the combustion chamber to transmit a laser beam of appropriate wavelength and to monitor the attenuation caused by absorption and scattering. The paper describes the concept of the measurement technique and its application to an optically accessed single-cylinder research engine. The engine is equipped with a transparent cylinder liner to allow investigation of the entire cylinder volume. In order to evaluate the feasibility of the method, the response of the line-of-sight absorption measurements to various engine operating modes was investigated. A comparison with actual engine data showed that fuel distribution, as governed by the injector operating mode, can have significant influence on combustion and cycle-to-cycle stability.
The Use of Tangential Offtakes for Energy Savings in Process Industries
Authors: O'Doherty T , Biffin M , Syred N 
Published: February 2007

Swirling flows occur in many processes within industry with little consideration given to pressure recovery. High tangential velocities occur in the exhaust nozzle which have been shown to persist for up to 20 pipe diameters downstream. This kinetic energy is dissipated by turbulence and friction and is unnecessarily lost. There is potential to recover this energy and reduce operating costs. This paper shows that a tangential offtake with associated diffuser can be used to recover up to 45 per cent of the pressure loss, with an accompanying reduction in energy consumption. It has particular application in the cement and process industries, and has been tested on a novel prototype cement raw meal preheater tower.
An Experimental Study on the Lateral Impact of Fully Clamped Mild Steel Pipes
Authors: Jones N , Birch S E , Birch R S , Zhu L , Brown M 
Published: February 2007

This report presents some experimental data that were recorded from 130 impact tests on mild steel pipes in two drop hammer rigs. The pipes were fully clamped across a span which was ten times the corresponding outside pipe diameters which lie between 22 and 324 mm. All of the pipes except five had wall thicknesses of 2 mm approximately and were impacted laterally by a rigid wedge indenter at the mid span, one-quarter span or near to a support. The impact velocities ranged up to 14 m/s and caused various failure modes. Some comparisons between two sets of experimental results indicate that the laws of geometrically similar scaling are almost satisfied over a scale range of approximately five.
A Method for Measuring the Dynamic Behaviour of the Rome-Florence High-Speed Track Switch Manoeuvring System
Authors: Bracciali A , Biagiotti M 
Published: February 2007

A mathematical model of the dynamic loads induced at a switch machine and at the rails by the passing of a train was formulated and validated by physical tests. Attention was focused specifically on the switch machine itself and therefore the data gathered refers strictly to the attachment elements of the switch machine to the track and locally the track in the area of attachment. The research is part of a series of projects that aim to establish the factors that must be considered during the design of a switch machine. An accurate mathematical model of the connection elements between the track and the switch machine is helpful, especially in this period of widespread adoption of high-speed trains and the new working conditions that this imposes, in order to ascertain the characteristics of the accelerations transmitted to the switch machine and, as a consequence, to design the connection system of the machine to the track, based on these criteria. The data acquired can also be used for the construction of a realistic test bench to further improve test procedures. The pursuit of this project is a fundamental step in understanding the factors involved in the design of a switch machine.
Design of High-Tech Metre Gauge Coaches on Indian Railways
Authors: Wadhwa K B L 
Published: February 2007

This paper traces the steps taken by the Research Designs and Standards Organisation (RDSO) of Indian Railways in the past to improve the metre gauge bogie design, which resulted in crossing the age-old speed barrier of 75 km/h, initially in 1977, when the Pink City Express was introduced at a maximum permissible speed of 100 km/h. The ‘Sperling ride index’ achieved at that time at the 110 km/h test speed was nearing 3.2 in the lateral mode and 3.33 in the vertical mode. Major design modifications are described that were carried out in the conventional metre gauge bogie/body, using indigenous technology, while designing high-tech metre gauge (MG) coaches. These are suitable for running on Indian Railways' track at a maximum permissible speed of 120 km/h and at the same time provide superior riding characteristics (with sperling ride index restricted to 2.75) comparable to those available on the main line coaches of 1000 mm gauge in the developed countries of the world.
British Aerospace Hawk into the 1990s
Authors: Chisnall G 
Published: February 2007

The paper covers a review of the British Aerospace Hawk aircraft programme. An overview of the main development events and entry into RAF service is included, which emphasizes the versatility of the basic concept. This was deliberately designed in by the original team in order to maximize the subsequent export potential of the aircraft. That this was an outstanding success is shown in the outline of the main export variants to date. This background gives context to the main body of the paper, in which the new Hawk aircraft developments, the 100 and 200 series respectively, are described. These advanced versions are intended to maintain the market dominance of Hawk throughout the 1990s and beyond. A final, brief review of the broader environment within which BAe is carrying out its private venture development of Hawk is included as a conclusion to the paper.
Working Top-Down: Cost Estimating before Development Begins
Authors: Pugh P G 
Published: February 2007

The present state of the art of cost estimating is reviewed with particular reference to its employment in connection with strategic decisions such as whether to launch a major project or not and, hence, when information concerning the project is limited and/or incomplete. The processes of ‘top-down’ cost estimating are described in sequence, starting with the gathering of data and its analysis followed by the formulation of costing assumptions and the derivation of cost-estimating relationships and ending in the application of those to yield cost estimates for the project in question. At each stage, the description is accompanied by practical advice and warnings of some common pitfalls.
A Three-Dimensional Morphometrical Study of the Distal Human Femur
Authors: Zoghi M , Hefzy M S , Fu K C , Jackson W T 
Published: February 2007

The objective of this paper is to present a method to describe the three-dimensional variations of the geometry of the three portions forming the distal part of the human femur: the medial and lateral femoral condyles and the intercondylar fossa. The contours of equally spaced sagittal slices were digitized on the distal femur to determine its surface topography. Data collection was performed using a digitizer system which utilizes low-frequency, magnetic field technology to determine the position and orientation of a magnetic field sensor in relation to a specified reference frame. The generalized reduced gradient optimization method was used to reconstruct the profile of each slice utilizing two primitives: straight-line segments and circular arcs. The profile of each slice within the medial femoral condyle was reconstructed using two circular arcs: posterior and distal. The profile of each slice within the lateral femoral condyle was reconstructed using three circular arcs: posterior, distal and anterior. Finally, the profile of each slice within the intercondylar fossa was reconstructed using two circular arcs: proximal-posterior and anterior, and a distal-posterior straight-line segment tangent to the proximal-posterior circular arc. Combining the data describing the profiles of the different slices forming the distal femur, the posterior portions of each of the medial and lateral femoral condyles were modelled using parts of spheres having an average radius of 20 mm. The anterior portion of the lateral condyle was approximated to a right cylinder having its circular base parallel to the sagittal plane with an average radius of 26 mm. The anterior portion of the intercondylar fossa was modelled using an oblique cylinder having its circular base parallel to the sagittal plane with an average radius of 22 mm. Furthermore, it is suggested that the distal portion of the lateral femoral condyle could be modelled using parts of two oblique cones while the distal portion of the medial femoral condyle could be modelled using a part of a single oblique cone, all cones having their circular bases parallel to the sagittal plane. It is also suggested that the posterior portion of the intercondylar fossa could be modelled using two oblique cones: a proximal cone having its base parallel to the sagittal plane and a distal cone having its base parallel to the frontal plane.
Shear Flow in Multi-Cell Sections
Authors: Grant C 
Published: February 2007

Traditional shear flow calculations for thin-walled multi-cell sections subjected to bending have ignored developments in topological algebra that exploit the independence of a network topology from its physical characteristics. By treating the section as a set of thin limbs connected at end nodes, network theory originally developed for electrical circuits can be applied to the problem. Flow rules similar to those formulated by Kirchhoff almost a century and a half ago are derived from conditions of equilibrium and compatibility. Each limb of the section behaves as a flow generator which drives the flow around the network. A complete solution can be derived for shear flow and for warping displacement in every limb by solving a relatively small number of fundamental circuit equations, equal to the number of independent circuits in the network. Matrices employed in the solution can be formed directly from the section's topological description.
Real Evaluation of Thermal Comfort in the Car Passenger Compartment
Authors: Della Rolle C , Romitelli G F 
Published: February 2007

Thermal comfort is in increasing demand from motorists bound to cover more mileage than ever before in car driving. As a result car makers are striving for improved climate conditions inside the car to meet passenger demand for more comfortable trips. A crucial question arises: ‘How can such improved conditions be developed into a product, when a dynamic system capable of responding to customers' subjective sensations does not exist?’ They cannot be achieved through the conventional ‘robust design’ philosophy or the engineering shelf approach whose main targets are: product development from the design stages, a reduced lead time to market, the set-up of competitive products, as well as an ‘objective’ measurement of the end product performance. What is actually needed in designing satisfactory air conditioners is a dynamic simulation system capable of instantly monitoring ‘subjective’ sensations variously experienced by car passengers. To this end, a piece of gauging equipment was set up at Fiat to measure thermo fluid dynamic comfort conditions in real time, and trace back any local discomfort sources. The manikin used for such tests was a valuable example of providing a measuring instrument to meet subjective customers' requirements. Such a dummy is normally employed in Fiat climatic wind tunnels to determine a comfort index according to standard specifications. Reference limits were defined to correlate both experimental and test results with actual customers' requirements. Useful suggestions were also included to improve every sensor used throughout testing.
The importance of NO2 in Bench Tests for Precombustion Deposits in the Spark Ignition Engine Intake System
Authors: Chou T L , Priestman G H 
Published: February 2007

Most previous laboratory-scale deposit simulator studies have considered mainly fuel or lubricant composition and properties, with no consideration of possible effects of NOx, which may affect initiation of the deposit formation process and the overall rate at which deposition occurs. In this study a laboratory-scale deposit simulator was developed which produced thin deposit films by spraying gasoline on to a heated aluminium sleeve to investigate the effects of temperature, NO2 and possible gasoline blending components, on deposit formation. The amount of deposit collected is indicative of the deposit-forming tendency of the test fuel. The deposit film composition was analysed using Fourier transform infrared (FTIR) spectroscopy. The results of the experiments indicate that deposit formation is indeed sensitive to NO2, in addition to the effects of temperature and the molecular structure of the hydrocarbons. Thus the effect of NOx in deposit-related studies is important and should not be ignored. The FTIR analyses showed that when using NO2 the deposits are of a very similar structure to those produced in a real engine test. The analyses also gave some insight into the role of NO2 in the deposit formation mechanism.
Identification of Support Conditions of Buried Pipes Using a Vibrating Pig
Authors: Köpke U G , Hunt H E M 
Published: February 2007

This paper describes a method for monitoring the variation in support condition of pipelines using a vibration technique. The method is useful for detecting poor support of buried pipelines and for detecting spanning and depth of cover in sub-sea lines. Variation in the pipe support condition leads to increased likelihood of pipe damage. Under roadways, poorly supported pipe may be damaged by vehicle loading. At sea, spanned sections of pipe are vulnerable to ocean current loading and also to snagging by stray anchors in shallow waters. A vibrating ‘pig’ has been developed and tested on buried pipelines. Certain features of pipe support, such as voids and hard spots, display characteristic responses to vibration, and these are measured by the vibrating pig. Post-processing of the measured vibration data is used to produce a graphical representation of the pipeline support and certain ‘feature characteristics’ are identified. In field tests on a pipeline with deliberately constructed support faults, features detected by the vibrating pig are in good agreement with the known construction.