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81.
At the very core of most automated sorting systems— for example, at airports for baggage handling and in parcel distribution centers for sorting mail—we find closed-loop tilt tray sortation conveyors. In such a system, trays are loaded with cargo as they pass through loading stations, and are later tilted upon reaching the outbound container dedicated to a shipment’s destination. This paper addresses the question of whether the simple decision rules typically applied in the real world when deciding which parcel should be loaded onto what tray are, indeed, a good choice. We formulate a short-term deterministic scheduling problem where a finite set of shipments must be loaded onto trays such that the makespan is minimized. We consider different levels of flexibility in how to arrange shipments on the feeding conveyors, and distinguish between unidirectional and bidirectional systems. In a comprehensive computational study, we compare these sophisticated optimization procedures with widespread rules of thumb, and find that the latter perform surprisingly well. For almost all problem settings, some priority rule can be identified which leads to a low-single-digit optimality gap. In addition, we systematically evaluate the performance gains promised by different sorter layouts. 相似文献
82.
Yunji Jung Yulong Xi Seoungjae Cho Wei Song Simon Fong Kyungeun Cho 《Multimedia Tools and Applications》2017,76(9):11429-11447
The objective of this study is to solve the problem of user data not being precisely received from sensors because of sensing region limitations in invoked reality (IR) space, distortion of colors or patterns by lighting, and blocking or overlapping of a user by other users. The sensing scope range is thus expanded using multiple sensors in the IR space. Moreover, user feature data are accurately identified by user sensing. Specifically, multiple sensors are employed when not all of user data are sensed because they overlap with data of other users. In the proposed approach, all clients share the user feature data from multiple sensors. Accordingly, each client recognizes that the user is the same individual on the basis of the shared data. Furthermore, the identification accuracy is improved by identifying the user features based on colors and patterns that are less affected by lighting. Therefore, accurate identification of the user feature data is enabled, even under lighting changes. The proposed system was implemented based on system performance analysis standards. The practicality and system performance in identifying the same person using the proposed method were verified through an experiment. 相似文献
83.
Yongrui?QinEmail author Quan?Z.?Sheng Nickolas?J.?G.?Falkner Lina?Yao Simon?Parkinson 《World Wide Web》2017,20(5):915-937
Since today’s real-world graphs, such as social network graphs, are evolving all the time, it is of great importance to perform graph computations and analysis in these dynamic graphs. Due to the fact that many applications such as social network link analysis with the existence of inactive users need to handle failed links or nodes, decremental computation and maintenance for graphs is considered a challenging problem. Shortest path computation is one of the most fundamental operations for managing and analyzing large graphs. A number of indexing methods have been proposed to answer distance queries in static graphs. Unfortunately, there is little work on answering such queries for dynamic graphs. In this paper, we focus on the problem of computing the shortest path distance in dynamic graphs, particularly on decremental updates (i.e., edge deletions). We propose maintenance algorithms based on distance labeling, which can handle decremental updates efficiently. By exploiting properties of distance labeling in original graphs, we are able to efficiently maintain distance labeling for new graphs. We experimentally evaluate our algorithms using eleven real-world large graphs and confirm the effectiveness and efficiency of our approach. More specifically, our method can speed up index re-computation by up to an order of magnitude compared with the state-of-the-art method, Pruned Landmark Labeling (PLL). 相似文献
84.
Keerthy Kusumam Tomáš Krajník Simon Pearson Tom Duckett Grzegorz Cielniak 《野外机器人技术杂志》2017,34(8):1505-1518
This paper describes a 3D vision system for robotic harvesting of broccoli using low‐cost RGB‐D sensors, which was developed and evaluated using sensory data collected under real‐world field conditions in both the UK and Spain. The presented method addresses the tasks of detecting mature broccoli heads in the field and providing their 3D locations relative to the vehicle. The paper evaluates different 3D features, machine learning, and temporal filtering methods for detection of broccoli heads. Our experiments show that a combination of Viewpoint Feature Histograms, Support Vector Machine classifier, and a temporal filter to track the detected heads results in a system that detects broccoli heads with high precision. We also show that the temporal filtering can be used to generate a 3D map of the broccoli head positions in the field. Additionally, we present methods for automatically estimating the size of the broccoli heads, to determine when a head is ready for harvest. All of the methods were evaluated using ground‐truth data from both the UK and Spain, which we also make available to the research community for subsequent algorithm development and result comparison. Cross‐validation of the system trained on the UK dataset on the Spanish dataset, and vice versa, indicated good generalization capabilities of the system, confirming the strong potential of low‐cost 3D imaging for commercial broccoli harvesting. 相似文献
85.
We show that biogeography-based optimization (BBO) is a generalization of a genetic algorithm with global uniform recombination (GA/GUR). Based on the common features of BBO and GA/GUR, we use a previously-derived BBO Markov model to obtain a GA/GUR Markov model. One BBO characteristic which makes it distinctive from GA/GUR is its migration mechanism, which affects selection pressure (i.e., the probability of retaining certain features in the population from one generation to the next). We compare the BBO and GA/GUR algorithms using results from analytical Markov models and continuous optimization benchmark problems. We show that the unique selection pressure provided by BBO generally results in better optimization results for a set of standard benchmark problems. We also present comparisons between BBO and GA/GUR for combinatorial optimization problems, include the traveling salesman, the graph coloring, and the bin packing problems. 相似文献
86.
87.
Chris JacksonAuthor Vitae Simon J. Hollis Author Vitae 《Microprocessors and Microsystems》2011,35(2):139-151
We address routing in Networks-On-Chip (NoC) architectures that use irregular mesh topologies with Long-Range Links (LRL). These topologies create difficult conditions for routing algorithms, as standard algorithms assume a static, regular link structure and exploit the uniformity of regular meshes to avoid deadlock and maintain routability. We present a novel routing algorithm that can cope with these irregular topologies and adapt to run-time LRL insertion and topology reconfiguration. Our approach to accommodate dynamic topology reconfiguration is to use a new technique that decomposes routing relations into two stages: the calculation of output ports on the current minimal path and the application of routing restrictions designed to prevent deadlock. In addition, we present a selection function that uses local topology data to adaptively select optimal paths.The routing algorithm is shown to be deadlock-free, after which an analysis of all possible routing decisions in the region of an LRL is carried out. We show that the routing algorithm minimises the cost of sub-optimally placed LRL and display the hop savings available. When applied to LRLs of less than seven hops, the overall traffic hop count and associated routing energy cost is reduced. In a simulated 8 × 8 network the total input buffer usage across the network was reduced by 6.5%. 相似文献
88.
Maria Koutantji Peter McCulloch Shabnam Undre Sanjay Gautama Simon Cunniffe Nick Sevdalis Rachel Davis Piers Thomas Charles Vincent Ara Darzi 《Cognition, Technology & Work》2008,10(4):275-285
We developed a module for surgical team training using briefings in simulated crisis scenarios and here we report preliminary
findings. Nine surgical teams (34 trainees) participated in a pre-training simulation, followed by an interactive workshop
on briefing and checklists, and then a post-training simulation. Both technical and non-technical skills were assessed via
observation during simulations by expert trainers who provided feedback on performances at the end of simulation. Trainees
also reported their attitudes to briefings and evaluated the training. Pre-training attitudes to briefing were positive, some
of which improved post-training and trainees’ evaluation of the training was positive. Surgeons’ technical skill improved
significantly post-training, but their decision-making skill was rated lower than other non-technical skills, compared to
other trainees. The training did not appear to greatly improve non-technical skill performance. Training surgical teams in
simulation is feasible but much more work is needed on measurement development and training strategy to confirm its efficacy
and utility. 相似文献
89.
An important area of Human Reliability Assessment in interactive systems is the ability to understand the causes of human
error and to model their occurrence. This paper investigates a new approach to analysis of task failures based on patterns
of operator behaviour, in contrast with more traditional event-based approaches. It considers, as a case study, a formal model
of an Air Traffic Control system operator’s task which incorporates a simple model of the high-level cognitive processes involved.
The cognitive model is formalised in the CSP process algebra. Various patterns of behaviour that could lead to task failure
are described using temporal logic. Then a model-checking technique is used to verify whether the set of selected behavioural
patterns is sound and complete with respect to the definition of task failure. The decomposition is shown to be incomplete
and a new behavioural pattern is identified, which appears to have been overlooked in the informal analysis of the problem.
This illustrates how formal analysis of operator models can yield fresh insights into how failures may arise in interactive
systems.
相似文献
Antonio Cerone (Corresponding author)Email: |
Simon ConnellyEmail: |
Peter LindsayEmail: |
90.
Steve Whittaker Simon Tucker Kumutha Swampillai Rachel Laban 《Personal and Ubiquitous Computing》2008,12(3):197-221
Although many recent systems have been built to support Information Capture and Retrieval (ICR), these have not generally
been successful. This paper presents studies that evaluate two different hypotheses for this failure, firstly that systems
fail to address user needs and secondly that they provide only rudimentary support for ICR. Having first presented a taxonomy
of different systems built to support ICR, we then describe a study that attempts to identify user needs for ICR. On the basis
of that study we carried out two user-oriented evaluations. In the first, we carried out a task-based evaluation of a state-of-the-art
ICR system, finding that it failed to provide users with abstract ways to view meetings data, and did not present users with
information categories that they considered to be important. In a second study, we introduce a new method for comparative
evaluation of different techniques for accessing meetings data. The second study showed that simple interface techniques that
extracted key information from meetings were effective in allowing users to extract gist from meetings data. We conclude with
a discussion of outstanding issues and future directions for ICR research. 相似文献