Heuristic approach to allocation of trucks in a transportation system

This paper considers the problem of how luggages should be assign to each truck for the transportation system consists of a depot, a fixed area and two types of luggages, called schedule problem. The main purpose of this paper is to propose a procedure for the problem subject to keep the balance of work loads among truck drivers. The procedure is based on 3 (heuristic) rules for replacing the addresses of each luggage with the ‘conventional address,’ converting size of each luggage into ‘weight’ and introducing a measure to keep the balance of work loads. The procedure consists of three stages according to ‘priority’ of the types of luggages. A case study is presented that demonstrate the practical usefulness of the procedure.     

Genetic programming: principles and applications

Genetic algorithms (GA) has given rise to two new fields of research where (global) optimisation is of crucial importance: ‘genetic based machine learning’ (GBML) and ‘genetic programming’ (GP). An introduction by the authors to GA and GBML was given in two previous papers (Eng. Appl. Artif. Intell. 9(6) (1996) 681; Eng. Appl. Artif. Intell. 13(4) (2000) 381). In this paper, the last domain (GP) will be introduced, thereby making up a trilogy which gives a general overview of the whole field. In this third part, an overview will be given of the basic concepts of GP as defined by Koza. A first (educational) example of GP is given by solving a simple symbolic regression of a sinus function. Finally, a more complex application is presented in which GP is used to construct the mathematical equations for an industrial process. To this end, the case study ‘fibre-to-yarn production process’ is introduced. The goal of this study is the automatic development of mathematical equations for the prediction of spinnability and (possible) resulting yarn strength. It is shown that (relatively) simple equations can be obtained which describe accurately 90% of the fibre-to-yarn database.     

Neural networks deterioration models for serviceability condition of buried stormwater pipes

Buried stormwater pipe networks play a key role in surface drainage systems for urban areas of Australia. The pipe networks are designed to convey water from rainfall and surface runoff only and do not transport sewage. The deterioration of stormwater pipes is commonly graded into structural and serviceability condition using CCTV inspection data in order to recognize two different deterioration processes and consequences. This study investigated the application of neural networks modelling (NNM) in predicting serviceability deterioration that is associated with reductions of pipe diameter until a complete blockage. The outcomes of the NNM are predictive serviceability condition for individual pipes, which is essential for planning proactive maintenance programs, and ranking of pipe factors that potentially contribute to the serviceability deterioration. In this study the Bayesian weight estimation using Markov Chain Monte Carlo simulation was used for calibrating the NNM on a case study in order to account for the uncertainty often encountered in NNM's calibration using conventional back-propagation weight estimation. The performance and the ranked factors obtained from the NNM were also compared against a classical model using multiple discrimination analysis (MDA). The results showed that the predictive performance of the NNM using Bayesian weight estimation is better than that of the NNM using conventional backpropagation and MDA model. Furthermore, among nine input factors, ‘pipe age’ and ‘location’ appeared insignificant whilst ‘pipe size’, ‘slope’, ‘the number of trees’ and ‘climatic condition’ were found consistently important over both models for serviceability deterioration process. The remaining three factors namely, ‘structure’, ‘soil’ and ‘buried depth’ might be redundant factors. A better and more consistent data collection regime may help to improve the predictive performance of the NNM and identify the significant factors.     

Consumer-oriented versus technology-oriented systems: designing services for people

Current computer systems providing consumer services seem to be designed primarily on ‘technology-oriented’ thinking, based on the ‘efficiency’ and the operating methods of the computer. To be of benefit to a wider variety of consumers, the system design may have to reflect a more ‘consumer-oriented’ approach, based on factors such as the needs, preferences, skills and knowledge of the user. This article demonstrates the differences between user evaluations of two computer systems designed to help in house-hunting, modelled on (a) consumer-oriented, and (b) technology-oriented approaches. Although particularly relevant to consumer systems, the article may have important implications for consumer and public services in general.     

What does the representation talk back to you?

Our research goal is to support designers with interactive systems by exploring the relationship among representations, their meanings, and their effects. This paper first outlines amplifying representational talkback (ART), a prototype system which we have developed to instantiate our research framework. We then reinterpret the essence of the ART system by illustrating the ART approach with other people's work in Semiotic Approaches to User Interface Design presented at the ACM CHI 2000 workshop. We identify critical aspects of the system from four points: (1) interactions with representations ‘I’ produced; (2) representations as indices for thoughts; (3) hands-on representations; and (4) limiting the automation. By having the ART system as an object-to-thing-with, we argue that communication with interactive computational tools had better been regarded as interaction with representations.     

Assessment of turbulence-transport models including non-linear rng eddy-viscosity formulation and second-moment closure for flow over a backward-facing step

A computational study is performed in which the predictive capabilities of a range of eddy-viscosity and second-moment-closure models are examined by reference to a separated flow behind a backward-facing step in an expanding channel. The models include three second-moment-closure variants, all being of the ‘Launder-Reece-Rodi’ type, two RNG k—ε forms, one combining the RNG approach with a non-linear eddy-viscosity formulation, and a low-Re k—ε model. The study demonstrates that to achieve a solution similar to that returned by second-moment closure, the RNG formulation needs to be implanted into a non-linear eddy-viscosity framework; neither returns, on its own, the correct behaviour, not even for mean-flow features. Moreover, relatively minor variations within second-moment closure—specifically, such relating to wall-induced effects on turbulence isotropisation and to stress diffusion—can significantly alter the overall performance of the closure. All models specifically designed to return realistic solutions for normal stresses seriously over-estimate anisotropy.     

Accurate and efficient nonlinear formulation of a nine-node shell element with spurious mode control

A nine-node Lagrangian shell finite element is presented for full nonlinear analysis of shell-type structures. The formulation is based on the assumption of large displacements, finite rotations, and small strains. The major focus is on the robustness, accuracy, and efficiency of the finite element. Uniform reduced (2 x 2) quadrature is used for evaluation of the element stiffness and recovery of element nodal forces, and an improved ‘ projection operator ’ procedure is employed for stabilization of the resulting spurious zero-energy modes. Efficient techniques are described for calculation of shape function derivatives, performance of local-to-global transformations, and determination of the ‘ stabilization coefficients ’ of the artificial mode control procedure. Numerical integration is employed through the thickness of the element for accurate evaluation of the plastic response in moderately thick shells. The projection operator employed for the mode stabilization is orthogonal to constant, linear, and quadratic displacement fields in the local Cartesian (x′, y′) coordinates at each of the 2 × 2 Gauss quadrature stations. As a result, the flat-plate pure-bending patch tests are not affected for arbitrary element sizes. The resulting element is essentially free of membrane and shear locking problems, and it has not shown any signs of spurious zero energy mode effects for a large number of linear and nonlinear tests.     

Defining a taxonomy of output modalities from an HCI perspective

The paper addresses an issue that must be resolved to produce a scientifically sound and practically useful reference model for intelligent multimedia presentation systems (IMP systems), namely that of providing, from the point of view of Human-Computer Interaction (HCI), a systematic understanding of the types of output information to be presented by IMP systems. The term ‘medium’, as it is used in the context of multimedia systems, is too coarse-grained for distinguishing between different types of output information. The paper introduces the notion of (representational) ‘modalities’ to enable sufficiently fine-grained distinctions to be made. For the term itself to be meaningful, ‘multimodal’ presentations must be composed of unimodal representations. In the approach presented, unimodal representations are defined from a small number of basic properties whose combinations specify the ‘generic’ level of a taxonomy of unimodal output modalities. Additional basic property distinctions serve to generate the more fine-grained ‘atomic’ and ‘sub-atomic’ levels in a hierarchical fashion. The taxonomy is set up with the aim of satisfying four basic requirements, viz. completeness, orthogonality, relevance and intuitiveness. A concluding discussion illustrates the practical use of the taxonomy.     

Locating systems at work: implications for the development of active badge applications

The paper reports findings from a sociological examination of the use of ‘active badge’ location information systems in two research laboratories. The use, distribution and control of location information is examined in reference to the social roles individuals have in what will be called the ‘moral order’ of workplaces. Suggestions for subsequent versions of location systems are made, and the use of sociological methods in design remarked.     

A computer program for an illness-death process with time-dependent covariates

This paper presents a computer program for estimating transition probabilities between states in a stochastic model for an illness-death process which incorporates time-dependent covariates. Parameters are estimated by the method of maximum likelihood using the Newton-Raphson iterative procedure. The program provides the standard normal deviate statistics as well as the value of the maximum of the likelihood function which can be used on repeated applications to test hypotheses concerning coefficients associated with covariates. Although this program is demonstrated by using a model with two ‘illness’ states and two ‘death’ states, it is also suitable for analyzing data with models involving fewer states, such as the analysis of survival time with covariates assuming a proportional hazard model.     

Unix and ADA - local area networks Helping users use Unix

When it comes time to write some computer code the hardware of choice today is a workstation running the Unix operating system. This paper considers the problem of new users faced with Unix. It presents a number of possible solutions and elaborates on one which provides a graphical help system. This latter help system may be accessed via a pointing device which leads initially to a picture of a help structure, nodes in the structure may be selected to display the associated help text. The texts are structure to address the needs of differing users, ‘new’ through to ‘competent’.     

Comparison of several discrete arithmetic schemes for simulating a constrained jet and a lab-scale tangential fired furnace

For tangential fired furnace, the false diffusion will occur when the flow is oblique to the grid lines. It is a major factor to cause serious errors to the prediction of tangential fired furnace. In order to decrease this false diffusion, this study has considered several alternative to the widely used upwind-differencing scheme with the aim of identifying which could be regarded as the most suitable in a general-purpose solving procedure for tangential furnace. The representations adopted are ‘hybrid’, ‘quick’ and ‘27-point’ treatments. Here, ‘27-point’ is a new discrete arithmetic scheme developed by the authors. All these schemes are used to simulate a constrained jet and a lab-scale tangential furnace and to compare solutions with the datum. Overall, the ‘27-point’ approximation emerged as the most satisfactory for simulating tangential furnace.     

Topological models for boundary representation: a comparison with n-dimensional generalized maps

In boundary representation, a geometric object is represented by the union of a ‘topological’ model, which describes the topology of the modelled object, and an ‘embedding’ model, which describes the embedding of the object, for instance in three-dimensional Euclidean space. In recent years, numerous topological models have been developed for boundary representation, and there have been important developments with respect to dimension and orientability. In the main, two types of topological models can be distinguished. ‘Incidence graphs’ are graphs or hypergraphs, where the nodes generally represent the cells of the modelled subdivision (vertex, edge, face, etc.), and the edges represent the adjacency and incidence relations between these cells. ‘Ordered’ models use a single type of basic element (more or less explicitly defined), on which ‘element functions’ act; the cells of the modelled subdivision are implicitly defined in this type of model. In this paper some of the most representative ordered topological models are compared using the concepts of the n-dimensional generalized map and the n-dimensional map. The main result is that ordered topological models are (roughly speaking) equivalent with respect to the class of objects which can be modelled (i.e. with respect to dimension and orientability).     

Thermal comfort and clothing insulation of resting tent occupants at high altitude

Thirty-nine males and 18 females, in six groups, participated in six high altitude treks (each lasting 3–4 weeks and climbing up to 5500 m) in the Himalaya and Karakoram. Inverse relationships between mean overnight total insulation (sleeping bag plus clothing) and air temperature in tents were recorded for all treks. Average overnight thermal sensations varied little with air temperature as the subjects modified their clothing insulation to maintain thermal sensations warmer than ‘neutral’ for all treks. For combined treks, subjects adjusted their mean overnight total insulation up to 7 clo for thermal sensations of between 0 (‘neutral’) and +1 (‘slightly warm’) on average, measured on the standard seven-point thermal sensation scale developed for everyday low-altitude conditions. Very few subjects (3% of all daily responses, on average) reported ‘cool’ or ‘cold’ sensations. General tent discomfort increased with altitude suggesting that subjects interpreted tent comfort predominantly in terms of thermal outdoor conditions.     

Continuous exposure to noisy work environments does affect preferred leisure noise levels

Although noise research concentrates principally on the workplace, recent studies have shown that preferred leisure noise may be as loud as 10 dBA higher than workplace levels. This two-phase study compared leisure noise preferences for workers who were exposed to either a ‘loud’ (≥ 85 dBA) or ‘not loud’ (< 85 dBA) work environment. Phase 1 examined 110 subjects' noise level preferences that were recorded before and after work for a one-day observation. Phase 2 recorded 12 additional subjects' preferences for five consecutive days. Analysis of both phases' results determined that leisure noise levels prior to work were not significantly different. Those exposed to the ‘loud’ environment preferred noise levels significantly higher (6.5 to 9 dBA) than their before work levels. Over the five consecutive days (Phase 2) only the ‘loud’ group preferred noise levels significantly higher after work (Day 5 versus Day 1). Thus, it can be concluded that ‘loud’ work environments and consecutive daily exposure to these environments do influence preferred leisure noise levels.     

The Internet: global information superhighway for the future

The information revolution is bringing people of different backgrounds from around the world into a global information superhighway. The Internet provides a global platform connecting thousands of networks around the world. There is a variety of information available on the Internet for the users. It has been considered as a forum for users to share worldwide information resources. The resources are so vast that many of us really cannot grasp or understand the Internet fully. It has become a ‘global information library’ which allows the users to participate in the group discussion, search for any information, start any discussion with others and so on. It can be considered as a hybrid environment of postal services, citizen's band radio, libraries and neighborhood community centers where we (‘we’ is mainly used in this paper in its generic form) can spend time with our friends (‘our’ is also mainly used generically). Internet users (Internauts) share jokes, gossip in on-line conferences and join special groups to keep abreast of their specific interests. The main objective of this tutorial is to discuss various services on the Internet, their implementations, various Internet tools, and interconnection to the Internet. Other important issues like the Internet addressing, domain name system, IP addressing, etc. are discussed in detail in order to understand some design concepts. A brief list of the different types of browsers for different platforms is given. A discussion on future of the Internet is given via different advances and tools defined to provide security, interconnectivity and other related issues.     

Addition and removal of information for a knowledge base with incomplete information

A knowledge base containing incomplete information in the form of disjunctions and negative information shows difficulties regarding the update operators. In this paper simple and straightforward definitions are given for an ‘adding’ operator (‘+’) and a ‘removing’ operator (‘−’) using Hebrand models.     

Getting to know each other—Artificial social intelligence for autonomous robots

This paper proposes a research direction to study the development of ‘artificial social intelligence’ of autonomous robots which should result in ‘individualized robot societies’. The approach is highly inspired by the ‘social intelligence hypothesis’, derived from the investigation of primate societies, suggesting that primate intelligence originally evolved to solve social problems and was only later extended to problems outside the social domain. We suggest that it might be a general principle in the evolution of intelligence, applicable to both natural and artificial systems. Arguments are presented why the investigation of social intelligence for artifacts is not only an interesting research issue for the study of biological principles, but may be a necessary prerequisite for those scenarios in which autonomous robots are integrated into human societies, interacting and communicating both with humans and with each other. As a starting point to study experimentally the development of robots' ‘social relationships’, the investigation of collection and use of body images by means of imitation is proposed. A specific experimental setup which we use to test the theoretical considerations is described. The paper outlines in what kind of applications and for what kind of robot group structures social intelligence might be advantageous.     

Quorum and connected dominating sets based location service in wireless ad hoc, sensor and actuator networks

Location service provides position of mobile destination to source node to enable geo-routing. In existing quorum-based location service protocols, destination node registers its location along a ‘column’ while source node makes a query along a ‘row’. Grid and quorum-based location service is based on division of network into square grids, and selecting ‘leader’ location server node in each grid. Location updates, leader reelection and information transfer are performed whenever destination and leader nodes are moving to a different grid. We propose here to apply connected dominating sets (DS) as an alternative to grids. We also improved basic quorum, and applied on DS-quorum (DS based quorum) better criterion for triggering local information exchanges and global location updates, by meeting two criteria: certain distance movement and certain number of observed link changes with (DS) nodes. Backbones created by DS nodes (using 1-hop neighborhood information) are small size, do not have a parameter like grid size, and preserve network connectivity without the help of other nodes. Location updates and destination searches are restricted to backbone nodes. Both methods use ‘hello’ messages to learn neighbors. While this suffices to construct DS, grid leader (re)election requires additional messages. Simulation results show that using DS as backbone for quorum construction is superior to using grid as backbone or no backbone at all. The proposed DS-quorum location service can achieve higher (or similar) success rate with much less communication overhead than grid-based approaches.     

The living in a lattice rule language

This paper presents a rule-based query language for an object-oriented database model. The database model supports complex objects, object identity, classes and types, and a class/type hierarchy. The instances are described by ‘object relations’ which are functions from a set of objects to value sets and other object sets. The rule language is based on object-terms which provide access to objects via the class hierarchy. Rules are divided into two classes: object-preserving rules manipulating existing objects (yielding a new ‘view’ on objects available in the object base) and object-generating rules creating new objects with properties derived from existing objects. The derived object sets are included in a class lattice. We give conditions for whether the instances of the ‘rules’ heads are ‘consistent’, i.e. represent object relations where the properties of the derived objects are functionally determined by the objects.