Evaluating the value of collaboration systems in collocated teams: A longitudinal analysis

Distributed work structure has increased the importance of group work. Consequently, the usage of collaboration systems that support group work has increased exponentially. However, limited research exists on why collocated group members use collaborative system and how their perceptions about the system change from project initiation to project completion. The study proposes resource management support, coordination support, and evaluation support as key aspects based on which collocated users form beliefs about collaboration system value. Based on technology acceptance model and expectancy disconfirmation theory, we propose a model that examines the evolution of user beliefs from pre to post-adoption stage. Further, we argue that users may engage in different information processing strategies as part of the belief change process. The research model was examined based on longitudinal data collected from student groups working on a software application development project over a three month period. The results show that users deemed all features to be valuable at the pre-adoption stage. However, at the post-adoption stage evaluation support was the only factor that had a direct influence on collaboration system usefulness. While the impact of other support factors was mediated through the confirmation process. Further, users engaged in high information processing in revising their beliefs about collaboration system features, when they experienced a high level of dissonance. On the contrary, a dual information processing approach was visible in the context of support features that required adjustment or update to beliefs from pre to post-adoption stage. The study provides three core areas around which designers can structure collaboration system features to make it more useful. It also provides theoretical insights into the process through which user cognitions about collaboration system value change over time.     

A model for output evaluation of an intelligent robotic assembly station

The evolution of intelligent robots has brought widespread changes in the concept of automatic assembly. An intelligent robot can successfully accomplish assembly in a multiple end product processing and unstructured component part(s) handling environment. This advanced capability of the robot dictates a major change in their basic output characteristics. For example, task service time of an intelligent assembly robot is no longer completely deterministic like that of an ordinary pick-and-place type robot. In this paper, a typical component insertion type assembly task is analyzed to show that the task service time is a random variable consisting of two (2) parts, a deterministic component and a stochastic component. Thus, with the assumption of exponential part input an assembly station served by a single intelligent robot is modeled as an M/G/1 queueing model. A robot availability factor is also introduced into the service time random variable. Closed form expressions for important system performance parameters are obtained under the assumption of three (3) different probability distributions for the stochastic part of the service time random variable.     

A parallel algorithm for the enumeration of the spanning trees of a graph

As is well known, the strategy of divide-and-conquer is widely used in problem solving. The method of partitioning is also a fundamental strategy for the design of a parallel algorithm. The problem of enumerating the spanning trees of a graph arises in several contexts such as computer-aided design and computer networks. A parallel algorithm for solving the problem is presented in this paper. It is based on the principle of the inclusion and exclusion of sets, and not directly based on the partitioning of the graph itself. The results of the preliminary experiments on a MIMD system appear promising.     

On the design of intelligent robotic agents for assembly

Robotic agents can greatly be benefited from the integration of perceptual learning in order to monitor and adapt to changing environments. To be effective in complex unstructured environments, robots have to perceive the environment and adapt accordingly. In this paper it is discussed a biology inspired approach based on the adaptive resonance theory (ART) and implemented on an KUKA KR15 industrial robot during real-world operations (e.g. assembly operations). The approach intends to embed naturally the skill learning capability during manufacturing operations (i.e., within a flexible manufacturing system).The integration of machine vision and force sensing has been useful to demonstrate the usefulness of the cognitive architecture to acquire knowledge and to effectively use it to improve its behaviour. Practical results are presented, showing that the robot is able to recognise a given component and to carry out the assembly. Adaptability is validated by using different component geometry during assemblies and also through skill learning which is shown by the robot’s dexterity.     

A note on the lower bound of edge guards of polyhedral terrains

Bose et al. [P. Bose et al., Guarding polyhedral terrains, Comput. Geom., Theory Appl. 6 (1997), pp. 173–185.] proved that ? (4n?4)/13 ? edge guards are sometimes necessary to guard an n-vertex polyhedral terrain. Subsequently, Kau?i? et al. [B. Kau?i?, B. ?alik, and F. Novak, On the lower bound of edge guards of polyhedral terrains, Int. J. Comput. Math. 80 (2003), pp. 811–814.] claimed to find an inconsistency in the proof and used Bose et al. ’s proof technique to prove a weaker lower bound of ? (2n?4)/7 ? edge-guards. They declared that a proof of the original lower bound of ? (4n?4)/13 ? remains an open issue. The purpose of this note is simply to point out that the issue is not open and that Bose et al. ’s original proof is correct. We present the original proof of ? (4n?4)/13 ? at a level of detail to hopefully remove any misunderstanding of the result.     

A comparison of two learning mechanisms for the automatic design of fuzzy diagnosis systems for rotating machinery

In this paper, we approach the problem of automatically designing fuzzy diagnosis rules for rotating machinery, which can give an appropriate evaluation of the vibration data measured in the target machines. In particular, we explain the implementation to this aim and analyze the advantages and drawbacks of two soft computing techniques: knowledge-based networks (KBN) and genetic algorithms (GA). An application of both techniques is evaluated on the same case study, giving special emphasis to their performance in terms of classification success and computation time.A reduced version of this paper first appeared under the title “A comparative assessment on the application of knowledge-based networks and genetic algorithms to the design of fuzzy diagnosis systems for rotating machinery”, published in the book “Soft Computing in Industry—Recent Appliactions” (Springer Engineering).     

Using genetic algorithms for early schedulability analysis and stress testing in real-time systems

Reactive real-time systems have to react to external events within time constraints: Triggered tasks must execute within deadlines. It is therefore important for the designers of such systems to analyze the schedulability of tasks during the design process, as well as to test the system's response time to events in an effective manner once it is implemented. This article explores the use of genetic algorithms to provide automated support for both tasks. Our main objective is then to automate, based on the system task architecture, the derivation of test cases that maximize the chances of critical deadline misses within the system; we refer to this testing activity as stress testing. A second objective is to enable an early but realistic analysis of tasks' schedulability at design time. We have developed a specific solution based on genetic algorithms and implemented it in a tool. Case studies were run and results show that the tool (1) is effective at identifying test cases that will likely stress the system to such an extent that some tasks may miss deadlines, (2) can identify situations that were deemed to be schedulable based on standard schedulability analysis but that, nevertheless, exhibit deadline misses.

Stability analysis for multi-agent systems using the incidence matrix: Quantized communication and formation control

The spectral properties of the incidence matrix of the communication graph are exploited to provide solutions to two multi-agent control problems. In particular, we consider the problem of state agreement with quantized communication and the problem of distance-based formation control. In both cases, stabilizing control laws are provided when the communication graph is a tree. It is shown how the relation between tree graphs and the null space of the corresponding incidence matrix encode fundamental properties for these two multi-agent control problems.     

A geometric method for determining joint rotations in the inverse kinematics of robotic manipulators

An inverse‐kinematics algorithm has been developed to evaluate the joint rotations of a robotic manipulator given the orientation of its hand link. The method mimics the way a person would determine the joint rotations by assembling the links comprising the robot mechanism and making adjustments in the joint displacements until the hand link is in the desired situation. An example is given where it is shown that the method is reasonably robust, can be applied to any design of robot, and is competitive with alternative highly‐mathematical, specific‐robot specialized, computational‐intensive schemes. ©2000 John Wiley & Sons, Inc.     

A strengthened analysis of a local algorithm for the minimum dominating set problem in planar graphs

In recent years growing interest in local distributed algorithms has widely been observed. This results from their high resistance to errors and damage, as well as from their good performance, which is independent of the size of the network. A local deterministic distributed algorithm finding an approximation of a Minimum Dominating Set in planar graphs has been presented by Lenzen et al., and they proved that the algorithm returns a 130-approximation of the Minimum Dominating Set. In this article we will show that the algorithm is two times more effective than was previously assumed, and we prove that the algorithm by Lenzen et al. outputs a 52-approximation to a Minimum Dominating Set. Therefore the gap between the lower bound and the approximation ratio of the best yet local deterministic distributed algorithm is reduced by half.     

Observability analysis for structured bilinear systems: A graph-theoretic approach

This paper is devoted to the generic observability analysis for structured bilinear systems using a graph-theoretic approach. On the basis of a digraph representation, we express in graphic terms the necessary and sufficient conditions for the generic observability of structured bilinear systems. These conditions have an intuitive interpretation and are easy to check by hand for small systems and by means of well-known combinatorial techniques for large-scale systems.     

A Fast Bit-Parallel Algorithm for Computing the Subset Partial Order

A given collection of sets has a natural partial order induced by the subset relation. Let the size N of the collection be defined as the sum of the cardinalities of the sets that comprise it. Algorithms have recently been discovered that compute the partial order in worst-case time O(N ² / log N) . This paper gives implementations of a variant of a previously proposed algorithm which exploit bit-parallel operations on a RAM with -bit words. One is shown to have a worst-case complexity of O(N ² log log N / log ² N) operations. This is the first known o(N ² / log N) worst case or randomized expected running time for this problem. Received March 1, 1996; revised December 24, 1997.     

A comparison of methods for the control of redundantly-actuated robotic systems

Mechanical hands, legged vehicles and cooperating manipulators are robotic systems containing closed kinematic chains which are typically driven by more actuators than required. As a result, the force distribution existing in these systems cannot be determined simply from the governing rigid-body statics or dynamics equations since these equations are underdetermined. Techniques have been proposed to overcome this obstacle — the most common being to formulate an optimization problem whose solution will be a force distribution which is optimal in a prescribed sense. A second approach which has been suggested is one in which the elasticity of the constituent bodies is considered in order to render the force-distribution problem determinate, in a manner analogous to the techniques typically used in structural mechanics to analyze hyperstatic structures. A third approach would be to deactivate certain actuators in order to reduce the number of unknowns so that the problem becomes determinate. In the present paper, these methods are compared and the first is shown to yield the best results.     

A genetic algorithm for the optimisation of assembly sequences

This paper describes a Genetic Algorithm (GA) designed to optimise the Assembly Sequence Planning Problem (ASPP), an extremely diverse, large scale and highly constrained combinatorial problem. The modelling of the ASPP problem, which has to be able to encode any industrial-size product with realistic constraints, and the GA have been designed to accommodate any type of assembly plan and component. A number of specific modelling issues necessary for understanding the manner in which the algorithm works and how it relates to real-life problems, are succinctly presented, as they have to be taken into account/adapted/solved prior to Solving and Optimising (S/O) the problem. The GA has a classical structure but modified genetic operators, to avoid the combinatorial explosion. It works only with feasible assembly sequences and has the ability to search the entire solution space of full-scale, unabridged problems of industrial size. A case study illustrates the application of the proposed GA for a 25-components product.     

电话自动计费器网络管理系统设计与实现

过去的电话自动计费器大都没有网络管理和自动拨号等功能。为了解决这些电话自动计费器不易管理、修改费率困难、收费漏洞大等问题,突破传统计费器的设计思路,运用计算机通信和网络技术设计了一种电话自动计费器网络管理系统,给出了管理中心、电话自动计费器等主要部件的软、硬件框图。该系统适用于城市公用电话自动计费器的网络管理。     

A methodology for evaluation of task performance in robotic systems: a case study in vision-based localization

We investigated the performance of an agent that uses visual information in a partially unknown and changing environment in a principled way. We propose a methodology to study and evaluate the performance of autonomous agents. We first analyze the system theoretically to determine the most important system parameters and to predict error bounds and biases. We then conduct an empirical analysis to update and refine the model. The ultimate goal is to develop self-diagnostic procedures. We show that although simple models can successfully predict some major effects, empirically observed performance deviates from theoretical predictions in interesting ways.     

A framework for modular analysis and exploration of heterogeneous embedded systems

The increasing complexity of heterogeneous systems-on-chip, SoC, and distributed embedded systems makes system optimization and exploration a challenging task. Ideally, a designer would try all possible system configurations and choose the best one regarding specific system requirements. Unfortunately, such an approach is not possible because of the tremendous number of design parameters with sophisticated effects on system properties. Consequently, good search techniques are needed to find design alternatives that best meet constraints and cost criteria. In this paper, we present a compositional design space exploration framework for system optimization and exploration using SymTA/S, a software tool for formal performance analysis. In contrast to many previous approaches pursuing closed automated exploration strategies over large sets of system parameters, our approach allows the designer to effectively control the exploration process to quickly find good design alternatives. An important aspect and key novelty of our approach is system optimization with traffic shaping.     

A comparison of parallelism in interface designs for computer-based learning environments

In this paper we discuss an experiment that was carried out with a prototype, designed in conformity with the concept of parallelism and the Parallel Instruction theory (the PI theory). We designed this prototype with five different interfaces, and ran an empirical study in which 18 participants completed an abstract task. The five basic designs were based on hypotheses of the PI theory that for solving tasks on screens all task relevant information must be in view on a computer monitor, as clearly as possible. The condition with two parallel frames and the condition with one long web page appeared to be the best design for this type of task, better than window versions that we normally use for our computer simulations on the web. We do not only describe the results of the abstract task in the five conditions, but we also discuss the results from the perspective of concrete, realistic tasks with computer simulations. The interface with two parallel frames is the best solution here, but also the interface with long web pages (‘virtual parallelism’) is a great favourite in practice when doing realistic tasks.     

A model for calculation of the costs of poor assembly ergonomics (part 1)

In product development there are many design requirements to meet and often tough project budgets to keep. Requirements that are considered not profitable will often be neglected, which affects assembly ergonomics. The objective of this study was to develop a calculation model for application in practice that enables calculation of costs of poor assembly quality related to assembly ergonomic conditions. The model is meant to be used by engineers and stakeholders in the design or redesign of manual assembly solutions. For that purpose, manual assembly tasks of 47061 cars at high, moderate and low physical load levels were analyzed with respect to assembly-related quality errors and corresponding action costs during production and on the market. The results showed that ergonomics high risk issues had 5–8 times as many quality errors as low risk issues and the earlier these were found the less were the action costs. The action costs for errors that were discovered late in assembly were 9.2 times more costly compared to early repair of errors in the factory. The action costs for quality errors that were found and corrected on the market were further 12.2 times more expensive to correct compared to actions taken in the factory. Examples are shown of how to apply the calculation model that was developed based on the obtained quality data.     

A method for the automatic analysis of the sleep macrostructure in continuum

Sleep staging is one of the most important tasks within the context of sleep studies. For more than 40 years the gold standard to the characterization of patient’s sleep macrostructure has been based on set of rules proposed by Rechtschaffen and Kales and recently modified by the American Academy of Sleep Medicine. Nevertheless the resulting map of sleep, the so-called hypnogram, has several limitations such as its low temporal resolution and the unnatural characterization of sleep through the assignment of discrete sleep states. This study reports an automatic method for the characterization of the structure of the sleep. The main intention is to overcome limitations of epoch-based sleep staging by obtaining a more continuous evolution of the sleep of the patient. The method is based on the use of fuzzy inference in order to avoid binary decisions, provide soft transitions and enable concurrent characterization of the different states. It is proven, in addition, how the new proposed continuous representation can still be used to generate the classical epoch-based hypnogram.