Search results

The unilateral axle counting sensor is an important railway signal device that detects a train. For efficient and stable detection, the amplitude of induced electromotive force and its changes must be big enough. Therefore, the purpose of this study is to find a way to design and optimize the sensor structure quickly and accurately.

With the help of extensive electromagnetic field calculations, the study puts forward a modified model based on the finite element method, establishes an independent air domain around the sensor, wheel and the railway and adopts a unique grid division method. It offers a design optimization method of the induction coil angles and its spatial location with respect to the excitation coil by using the combination weighting algorithm.

The modified modeling method can greatly reduce the number of finite element mesh and the operation time, and the method can also be applied to other areas. The combination weighting algorithm can optimize the structure of the sensor quickly and accurately.

This study provides a way to design and optimize the structure of the sensor and a theoretical basis for the development. The results can improve and expand the technology of the axle counting sensor.

Investigates the differences in protocols between arbitral tribunals and courts, with particular emphasis on US, Greek and English law. Gives examples of each country and its way of using the law in specific circumstances, and shows the variations therein. Sums up that arbitration is much the better way to gok as it avoids delays and expenses, plus the vexation/frustration of normal litigation. Concludes that the US and Greek constitutions and common law tradition in England appear to allow involved parties to choose their own judge, who can thus be an arbitrator. Discusses e‐commerce and speculates on this for the future.

Gives introductory remarks about chapter 1 of this group of 31 papers, from ISEF 1999 Proceedings, in the methodologies for field analysis, in the electromagnetic community. Observes that computer package implementation theory contributes to clarification. Discusses the areas covered by some of the papers ‐ such as artificial intelligence using fuzzy logic. Includes applications such as permanent magnets and looks at eddy current problems. States the finite element method is currently the most popular method used for field computation. Closes by pointing out the amalgam of topics.

A computational procedure based on a hybrid Lagrangian‐Eulerian discrete‐vortical element formulation and conformal transformation schemes are employed in this study to simulate the interaction of an air jet with swirling air flow inside a two‐dimensional cylinder. Such an investigation is of importance to many flow‐related industrial and environmental problems, such as mixing, cooling, combustion and dispersion of air‐borne or water‐borne contaminants because of the role of vortices in the global transport of matter and heat. The basis for the simulation is discussed and numerical results compared with theoretical results for the velocity field and streamfunction obtained by the method of images. The swirling air motion and the features of a real jet are well simulated and numerical results are validated by predictions of theory to within 20 per cent. To illustrate the merging and interaction processes of vortices and the formation of large eddies, velocity vectors, particle trajectories and streamline contours are presented.

The recently proposed concept solution for improving blast-survivability of the light tactical military vehicles is critically assessed using combined finite-element/discrete-particle computational methods and tools. The purpose of this paper is to propose a concept that involves the use of side-vent-channels attached to the V-shaped vehicle underbody. Since the solution does not connect the bottom and the roof or pass through the cabin of a light tactical vehicle, this solution is not expected to: first, reduce the available cabin space; second, interfere with the vehicle occupants’ ability to scout the surroundings; and third, compromise the vehicle’s off-road structural durability/reliability. Furthermore, the concept solution attempts to exploit ideas and principles of operation of the so-called “pulse detonation” rocket engines in order to create a downward thrust on the targeted vehicle.

To maximize the downward thrust effects and minimize the extent of vehicle upward movement, standard engineering-optimization methods and tools are employed for the design of side-vent-channels.

The results obtained confirmed the beneficial effects of the side-vent-channels in reducing the blast momentum, although the extent of these effects is relatively small (3-4 percent).

To the authors’ knowledge, the present work is the first public-domain report of the side-vent-channel blast-mitigation concept.

To present numerical approaches to the solution of physically coupled non‐linear problems, which frequently happen to be characterized by their multi‐domain character.

By adopting coupled solution strategies a considerable attention is devoted, in order to obtain a computationally efficient numerical algorithm, to the selection of appropriate space and time discretization, as well as to a proper discrete approximation method used.

Coupling of two methods, the finite element method and the boundary element method, respectively, has proved to be computationally exceedingly advantageous, particularly in case of moving domains.

As specific case studies computer simulation of an induction heating problem and a mushy‐state forming problem are considered. A thorough discussion on the coupling effects, characterizing the evolutions of respective physical quantities' fields, is given, and their impact on those evolutions is identified.

This paper presents efficient numerical strategies for the solution of a certain class of multi‐physics and multi‐domain problems.

The purpose of this paper is to apply the Developmental Model of Vocational Excellence (DMVE) in the domain of air traffic control and to describe the characteristics and predictors related to air traffic controllers’ (ATCO) vocational expertise and excellence. Based on DMVE, the study analyses the role of natural abilities (gifts), intrinsic characteristics (self-regulatory abilities) and extrinsic conditions (domain and non-domain specific factors) in ATCOs’ vocational development.

The target population of the multiple case study consisted of ATCOs in Finland (N = 300), of which 28 were interviewed. The interviewees represented four different airports. Initially, three key personnel interviews were conducted to validate the structured theme interview instrument that was subsequently used for the 28 interviews. The data set also included the ATCOs’ aptitude test scores and training records. Employee assessments were used to determine their on-the-job performance level (expertise vs excellence). The research questions were examined using theoretical concept analysis. The qualitative data analysis was conducted with content analysis and Bayesian classification modelling.

The findings indicate that cognitive skills, self-reflection, volition and goal-orientation are considered to be ATCOs’ most important vocational characteristics in addition to interpersonal, intrapersonal and spatial skills. The main differences between the ATCOs representing vocational expertise and those representing vocational excellence were related to self-regulation; motivation and volition in particular proved to be somewhat stronger in the latter group.

It was acknowledged that there are limitations in the present study. First, the four airports were not selected randomly. Although they represent different types of airports (and ATCO job profiles) in Finland quite well, future studies should include comparative aspect to airports in other countries. Second, the number of participants (N = 28) in the study was quite small, limiting generalization of the results to the target population (N = 300). Future research on this domain should be extended to include also quantitative measurements, allowing more generalizable results. Third, although the analysis for the research question 3 was based on a technique that is not sensitive to missing values (BCM), missing data in ATCOs’ aptitude test scores, training records and employee assessments added uncertainty to the results.

ATCOs’ highly controlled and pre-defined work presents a challenge to work motivation, which is seen as one of the determining factors in safety in air traffic controlling (ATC). In the future, more emphasis should be placed on the prerequisites of professional development such as leadership (human resource management, feedback, employees’ opportunity to influence), working environment (physical and social environment), educational possibilities and career progression, as well as professional benefits (salary and working hours).

Although ATC is a fairly studied topic since 1970s, most studies related to ATCOs have concentrated on training, learning on the job, cognitive capacity and processing and stress tolerance. This study extends the emerging research in the field on self-regulation by adopting DMVE to investigate its role, alongside natural abilities and domain and non-domain specific factors, to vocational talent development in different skill acquisition stages.

Better identification of comfort preferences and occupant behaviour drivers is expected to improve buildings’ user-centred designs and energy operations. To understand the underline drivers of occupant behaviours in office buildings, this study aims to evaluate the inter-relationships among occupant energy behaviours, indoor environmental quality satisfaction, user control and social-psychological factors influencing occupant behaviours in New Zealand offices.

Using an occupant perception survey, this study identifies the occupant behaviour patterns based on multi-domain comfort preferences. A case study was conducted in five office spaces of a university in Auckland, New Zealand. Data were collected from 52 occupants and analysed using descriptive and binary logistic regression analysis. Indoor environmental quality, user control, motivational, opportunity and ability factors were the independent variables considered. A model to predict the behaviours using environmental, building and social-psychological aspects was developed.

The results showed that the primary sources of indoor environmental quality discomfort were related to thermal and air quality, while occupants’ indoor environmental quality satisfaction correlated with their comfort preferences. The outcomes emphasise how the connection between building systems and occupants’ comfort preferences affect the choice of occupant behaviours in offices. Also, the primary occupant behaviours were drinking hot and cold beverages, opening/closing windows and internal doors and adjusting clothing. The binary logistic regression analysis showed that occupants’ perceived user control satisfaction is the main driver for increasing window actions. No other independent variable showed a statistically significant association with other behaviours.

This study adopted a novel approach to assess the combined effects of comfort preferences, occupant energy behaviours and various environmental, building and socio-psychological factors for modelling energy-saving behaviours in office buildings.

The purpose of this paper is to address the problem of substitution of steel with fiber-reinforced polymer-matrix composite in military-vehicle hull-floors, and identifies and quantifies the associated main benefits and shortcomings.

The problem is investigated using a combined finite-element/discrete-particle computational analysis. Within this analysis, soil (in which a landmine is buried), gaseous detonation products and air are modeled as assemblies of discrete, interacting particles while the hull-floor is treated as a Lagrangian-type continuum structure. Considerable effort has been invested in deriving the discrete-material properties from the available experimental data. Special attention has been given to the derivation of the contact properties since these, in the cases involving discrete particles, contain a majority of the information pertaining to the constitutive response of the associated materials. The potential ramifications associated with the aforementioned material substitution are investigated under a large number of mine-detonation scenarios involving physically realistic ranges of the landmine mass, its depth of burial in the soil, and the soil-surface/floor-plate distances.

The results obtained clearly revealed both the benefits and the shortcomings associated with the examined material substitution, suggesting that they should be properly weighted in each specific case of hull-floor design.

To the authors’ knowledge, the present work is the first public-domain report of the findings concerning the complexity of steel substitution with composite-material in military-vehicle hull-floors.

In Part I, an intelligent acoustic emission (AE) locator is described while the Part II discusses a blind source separation, time delay estimation and location of two continuous AE sources. AE analysis is used for characterization and location of developing defects in materials. AE sources often generate a mixture of various statistically independent signals. A difficult problem of AE analysis is a separation and characterization of signal components when the signals from various sources and the mode of mixing are unknown. Recently, blind source separation (BSS) by independent component analysis (ICA) has been used to solve these problems. The purpose of this paper is to demonstrate the applicability of ICA to locate two independent simultaneously active AE sources on an aluminum band specimen. The method is promising for non‐destructive testing of aircraft frame structures by AE analysis.