scholarly journals Analyzing Evolutionary Optimization in Noisy Environments

2018 ◽  
Vol 26 (1) ◽  
pp. 1-41 ◽  
Author(s):  
Chao Qian ◽  
Yang Yu ◽  
Zhi-Hua Zhou
Keyword(s):  
Minimum Spanning Tree ◽  
Search Algorithm ◽  
Combinatorial Problems ◽  
Maximum Matching ◽  
Noise Tolerance ◽  
Threshold Selection ◽  
Noisy Environments ◽  
Exact Evaluation ◽  
Negative Effect ◽  
The One

Many optimization tasks must be handled in noisy environments, where the exact evaluation of a solution cannot be obtained, only a noisy one. For optimization of noisy tasks, evolutionary algorithms (EAs), a type of stochastic metaheuristic search algorithm, have been widely and successfully applied. Previous work mainly focuses on the empirical study and design of EAs for optimization under noisy conditions, while the theoretical understandings are largely insufficient. In this study, we first investigate how noisy fitness can affect the running time of EAs. Two kinds of noise-helpful problems are identified, on which the EAs will run faster with the presence of noise, and thus the noise should not be handled. Second, on a representative noise-harmful problem in which the noise has a strong negative effect, we examine two commonly employed mechanisms dealing with noise in EAs: reevaluation and threshold selection. The analysis discloses that using these two strategies simultaneously is effective for the one-bit noise but ineffective for the asymmetric one-bit noise. Smooth threshold selection is then proposed, which can be proved to be an effective strategy to further improve the noise tolerance ability in the problem. We then complement the theoretical analysis by experiments on both synthetic problems as well as two combinatorial problems, the minimum spanning tree and the maximum matching. The experimental results agree with the theoretical findings and also show that the proposed smooth threshold selection can deal with the noise better.

Multi-AUV Underwater Cooperative Search Algorithm based on Biological Inspired Neurodynamics Model and Velocity Synthesis

2015 ◽  
Vol 68 (6) ◽  
pp. 1075-1087 ◽  
Author(s):  
Xiang Cao ◽  
Daqi Zhu
Keyword(s):  
Autonomous Underwater Vehicle ◽  
Search Algorithm ◽  
Integrated Approach ◽  
Underwater Vehicle ◽  
Ocean Currents ◽  
Ocean Current ◽  
Cooperative Search ◽  
Search Path ◽  
Negative Effect ◽  
Underwater Target

Ocean currents impose a negative effect on Autonomous Underwater Vehicle (AUV) underwater target searches, which lengthens the search paths and consumes more energy and team effort. To solve this problem, an integrated algorithm is proposed to realise multi-AUV cooperative search in dynamic underwater environments with ocean currents. The proposed integrated algorithm combines the Biological Inspired Neurodynamics Model (BINM) and Velocity Synthesis (VS) method. Firstly, the BINM guides a team of AUVs to achieve target search in underwater environments; BINM search requires no specimen learning information and is thus easier to apply to practice, but the search path is longer because of the influence of ocean current. Next the VS algorithm offsets the effect of ocean current, and it is applied to optimise the search path for each AUV. Lastly, to demonstrate the effectiveness of the proposed integrated approach, simulation results are given in this paper. It is proved that this integrated algorithm can plan shorter search paths and thus the energy consumption is lower compared with BINM.

Intelligent Process Planning Implemented As an Integrated Module of CIM

1997 ◽  
Author(s):  
Dusan N. Sormaz ◽  
Behrokh Khoshnevis
Keyword(s):  
Process Planning ◽  
Search Algorithm ◽  
Computer Integrated Manufacturing ◽  
Planning System ◽  
Process Selection ◽  
Process Sequencing ◽  
Knowledge Based ◽  
Completion Process ◽  
Integrative Process ◽  
The One

Abstract In this paper we describe an architecture of a new integrative process planning system as a part of computer integrated manufacturing research system. The process planning procedure is comprised of three phases: feature completion, process selection and process sequencing. We applied a knowledge-based approach to feature completion and process selection, and the space search algorithm for process sequencing. Description of these phases is provided and underlying knowledge representation explained. Integration between the process planning, on the one side, and CAD and scheduling, on the other, is discussed. System implementation has been described and several examples of the system execution are shown.

scholarly journals Minimizing Power Consumption of an Experimental HVAC System Based on Parallel Grid Searching

Energies ◽  
2020 ◽  
Vol 13 (8) ◽  
pp. 2083 ◽  
Author(s):  
Wangqi Xiong ◽  
Jiandong Wang
Keyword(s):  
Power Consumption ◽  
Graphics Processing Units ◽  
Optimization Problem ◽  
Search Algorithm ◽  
Experimental Studies ◽  
Optimal Solution ◽  
Hvac System ◽  
Convex Optimization Problem ◽  
The One ◽  
Graphics Processing

This paper proposes a parallel grid search algorithm to find an optimal operating point for minimizing the power consumption of an experimental heating, ventilating and air conditioning (HVAC) system. First, a multidimensional, nonlinear and non-convex optimization problem subject to constraints is formulated based on a semi-physical model of the experimental HVAC system. Second, the optimization problem is parallelized based on Graphics Processing Units to simultaneously compute optimization loss functions for different solutions in a searching grid, and to find the optimal solution as the one having the minimum loss function. The proposed algorithm has an advantage that the optimal solution is known with evidence as to the best one subject to current resolutions of the searching grid. Experimental studies are provided to support the proposed algorithm.

scholarly journals Die taal of die cheetah? Perspektiewe op die belang van taalsigbaarheid by die nuwe Vrystaatse nommerplaat as openbare teken

Literator ◽  
2007 ◽  
Vol 28 (2) ◽  
pp. 119-144 ◽  
Author(s):  
T. Du Plessis
Keyword(s):  
Graphic Design ◽  
Motor Vehicle ◽  
The Other ◽  
Free State ◽  
Linguistic Features ◽  
Positive Identification ◽  
Other Hand ◽  
Negative Effect ◽  
The One

The language or the cheetah? Perspectives on the importance of language visibility on the new Free State number plate as public sign This article investigates the importance of language visibility on the new Free State number plate, on the basis of a survey that was conducted during 2002 among a representative group of motor-vehicle owners in the province. This survey tested the opinions of respondents in respect of two aspects. On the one hand, opinions regarding the illustrated design of the new number plate which was introduced in 2002, were tested; and on the other hand, opinions concerning the linguistic features of the number plate were also investigated. In this article, selected responses to two sets of questions relating to the above will be compared, in order to determine the effect of the graphic design of the new number plate on respondents’ opinions regarding language visibility. A positive identification therewith would provide an indication of the degree to which the negative effect of reduced language visibility on the illustrated number plate in the province’s two main languages, by this minimised.

Not too close, not too far: Urbanisation and life satisfaction along the urban hierarchy

Urban Studies ◽  
2020 ◽  
pp. 004209802096239
Author(s):  
Camilla Lenzi ◽  
Giovanni Perucca
Keyword(s):  
Life Satisfaction ◽  
Urban Economics ◽  
Positive Association ◽  
Well Being ◽  
City Size ◽  
Urban Hierarchy ◽  
Developed Economies ◽  
Positive Externalities ◽  
Negative Effect ◽  
The One

Empirical evidence on the effect of urbanisation on individual self-reported well-being generally points to a negative effect of urbanisation and city size, at least in most developed economies. This article aims to re-assess this conclusion by claiming that this approach overlooks the fact that a city’s positive externalities may expand well beyond the urban boundaries, as postulated in urban economics theory. Based on survey data on self-reported life satisfaction derived from different waves of Eurobarometer surveys in the period 2005–2010 covering 21 European Union member countries, the article empirically verifies the existence of a positive association between urbanisation and individual well-being, depending on the proximity to settings of higher rank in the urban hierarchy. In particular, it shows that the higher the distance from a city larger than the one of residence of the respondent, the lower the probability of being satisfied with life.

Voice Activity Based on Noise Estimation in Noisy Environments

2012 ◽  
Vol 239-240 ◽  
pp. 409-414
Author(s):  
Shi Lin Liu ◽  
Zheng Pei
Keyword(s):  
Decision Trees ◽  
Noise Level ◽  
Wavelet Decomposition ◽  
Noise Estimation ◽  
Noisy Environments ◽  
Zero Crossing ◽  
Zero Crossing Rate ◽  
Simulation Results ◽  
The One ◽  
Voice Activity

An improved project based on decision trees in noisy environments is proposed for robust endpoints detection. Firstly, the noise level of the environment is estimated by wavelet decomposition, and then whether the denoising process is done according to the noise level is determined. Next, the thresholds are obtained by decision trees for the signal. Finally, endpoints are detected by the double thresholds on different importance of the energy and zero-crossing rate (ZCR) in the corresponding situation. The simulation results indicate that the proposed method based on noise estimation can obtain the same accurate data by computing less than the one with decision trees.

Analysis and interpretation of long term light trap data for Helicoverpa punctigera (Lepidoptera; Noctuidae) in Australia: population changes and forecasting pest pressure

1996 ◽  
Vol 86 (5) ◽  
pp. 547-557 ◽  
Author(s):  
D. Maelzer ◽  
M.P. Zalucki ◽  
R. Laughlin
Keyword(s):  
Light Trap ◽  
South Australia ◽  
Positive Influence ◽  
Weather Data ◽  
Early Season ◽  
South Wales ◽  
Spring Generation ◽  
Negative Effect ◽  
The One ◽  
Trap Catches

AbstractUsing regression analysis the early season dynamics of Helicoverpa punctigera (Wallengren) were determined from long series of light trap catches (10–19 years) from three sites in Australia (Narrabri and Trangie in New South Wales, and Turretfield in South Australia). The size of the second spring generation (G2, the one causing major pest problems in summer cropping regions) was strongly related to the size of the first spring generation (G1). In most cases, rainfall in early winter had a positive influence on the size of G2, whereas rainfall in spring had a negative effect. Regressions were found to account for 49 to 93% of the annual variation in G2, depending on site. The use of light trap catches and weather data to forecast pest levels from a few months to a few weeks in advance is discussed, along with the improved understanding of early season H. punctigera dynamics.

A unified alignment algorithm for bilingual data

2011 ◽  
Vol 19 (1) ◽  
pp. 33-60 ◽  
Author(s):  
CHRISTOPH TILLMANN ◽  
SANJIKA HEWAVITHARANA
Keyword(s):  
Dynamic Programming ◽  
Speech Recognition ◽  
Search Algorithm ◽  
Alignment Algorithm ◽  
Comparable Data ◽  
Beam Search ◽  
Sentence Level ◽  
Unified Algorithm ◽  
The One ◽  
Document Level

AbstractThe paper presents a novel unified algorithm for aligning sentences with their translations in bilingual data. With the help of ideas from a stack-based dynamic programming decoder for speech recognition (Ney 1984), the search is parametrized in a novel way such that the unified algorithm can be used on various types of data that have been previously handled by separate implementations: the extracted text chunk pairs can be either sub-sentential pairs, one-to-one, or many-to-many sentence-level pairs. The one-stage search algorithm is carried out in a single run over the data. Its memory requirements are independent of the length of the source document, and it is applicable to sentence-level parallel as well as comparable data. With the help of a unified beam-search candidate pruning, the algorithm is very efficient: it avoids any document-level pre-filtering and uses less restrictive sentence-level filtering. Results are presented on a Russian–English, a Spanish–English, and an Arabic–English extraction task. Based on simple word-based scoring features, text chunk pairs are extracted out of several trillion candidates, where the search is carried out on 300 processors in parallel.

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