Accelerated Method for Surface View Factor Evaluation Based on Error Estimation

2014 ◽  
Vol 136 (7) ◽  
Author(s):  
Roman Koptelov ◽  
German Malikov ◽  
Vladimir Lisienko ◽  
Raymond Viskanta
Keyword(s):  
Error Estimation ◽  
Standard Method ◽  
Continuous Furnace ◽  
Computation Time ◽  
View Factor ◽  
Simple Criterion ◽  
Surface View ◽  
Minimum Number ◽  
Factor Evaluation

An algorithm for choosing the number of quadrature nodes before calculation of a view factor is proposed. Simple criterion is introduced that allows one to estimate the error in the computed view factor. The algorithm allows one to save much computation time by always using the minimum number of nodes for each pair of surface zones and insures a desired accuracy. The algorithm is applied for model of a continuous furnace and is compared with a standard method which uses predefined number of nodes at each surface. The proposed algorithm is many times faster and also more accurate than the standard one.

scholarly journals Analyzing Tie-Breaking Strategies for the A* Algorithm

2018 ◽  
Author(s):  
Augusto B. Corrêa ◽  
André G. Pereira ◽  
Marcus Ritt
Keyword(s):  
State Space ◽  
Standard Method ◽  
State Of The Art ◽  
The State ◽  
Heuristic Function ◽  
A Algorithm ◽  
Minimum Number ◽  
Previous State

For a given state space and admissible heuristic function h there is always a tie-breaking strategy for which A* expands the minimum number of states [Dechter and Pearl, 1985]. We say that these strategies have optimal expansion. Although such a strategy always exists it may depend on the instance, and we currently do not know a tie-breaker that always guarantees optimal expansion. In this paper, we study tie-breaking strategies for A*. We analyze common strategies from the literature and prove that they do not have optimal expansion. We propose a novel tie-breaking strategy using cost adaptation that has always optimal expansion. We experimentally analyze the performance of A* using several tie-breaking strategies on domains from the IPC and zero-cost domains. Our best strategy solves significantly more instances than the standard method in the literature and more than the previous state-of-the-art strategy. Our analysis improves the understanding of how to develop effective tie-breaking strategies and our results also improve the state-of-the-art of tie-breaking strategies for A*.

scholarly journals Investigation of Sheltering Effect on Global Solar Radiation Data Measured by Weather Stations

2019 ◽  
Vol 93 ◽  
pp. 02002
Author(s):  
Keh-Chin Chang ◽  
Hung-Hsun Chen
Keyword(s):  
Solar Radiation ◽  
Calculation Method ◽  
Global Solar Radiation ◽  
View Factor ◽  
Weather Station ◽  
Measuring Process ◽  
Radiation Data ◽  
Factor Evaluation ◽  
Weather Stations ◽  
Sheltering Effect

In instalment of pyranometers at the weather stations for measuring global solar radiation, it often cannot avoid appearance of obstacles in their surroundings. Investigation of sheltering effect on measurement of global solar radiation is performed through introducing the shelter view factor. Evaluation of the shelter view factor is made by means of a fisheye-lens photograph together with the calculation method developed by Steyn (1980). Taitung weather station (TWS) is chosen for the study. The shelter view factor for the pyranometer installed at TWS is estimated to be 11.8%. Measurements of global solar radiation are conducted at a place where is located nearby TSW but with the condition of zero shelter view factor. Comparison of the data measured at these two sites indicates 4% - 25% deviations of global solar radiation observed in different months of 2017. It suggests a need of the correction to the sheltering effect in the measuring process of global solar radiation at the weather stations except those who are not subject to surrounding obstacles in the sky dome.

Fast Optimization of a Linear Induction Motor by 3-Level Space Mapping Technique

2013 ◽  
Vol 416-417 ◽  
pp. 195-202
Author(s):  
Jin Lin Gong ◽  
Frédéric Gillon ◽  
Pascal Brochet
Keyword(s):  
Computation Time ◽  
Kriging Model ◽  
Space Mapping ◽  
Mapping Technique ◽  
3D Fem ◽  
Linear Induction Motor ◽  
Electric And Magnetic Fields ◽  
Minimum Number ◽  
Mapping Techniques ◽  
Output Space

For the design and analysis of a linear electrical motor, an analytical solution of electric and magnetic fields is barely achieved with the required accuracy, due to the end and edge effects, and the nonlinear characteristic of the materials. Optimal design with the finite element models (FEM) is often expensive, in terms of the computation time. The space-mapping techniques allow having an affordable computation cost with a minimum number of computationally expensive FEM evaluations. In this paper, based on a kriging model, a 2D FEM and a 3D FEM, a 3-level adapted output space-mapping technique is employed. The results show that the proposed algorithm allows saving a substantial amount of computation time compared to conventional 2-level output space-mapping technique.

scholarly journals A New Technique of Removing Blind Spots to Optimize Wireless Coverage in Indoor Area

2013 ◽  
Vol 2013 ◽  
pp. 1-10
Author(s):  
A. W. Reza ◽  
K. Dimyati ◽  
K. A. Noordin ◽  
M. J. Islam ◽  
M. S. Sarker ◽  
...  
Keyword(s):  
Computation Time ◽  
Blind Spot ◽  
New Technique ◽  
Maximum Coverage ◽  
Coverage Model ◽  
Minimum Number ◽  
Wireless Coverage ◽  
A New Technique ◽  
Coverage Prediction ◽  
Blind Spots

Blind spots (or bad sampling points) in indoor areas are the positions where no signal exists (or the signal is too weak) and the existence of a receiver within the blind spot decelerates the performance of the communication system. Therefore, it is one of the fundamental requirements to eliminate the blind spots from the indoor area and obtain the maximum coverage while designing the wireless networks. In this regard, this paper combines ray-tracing (RT), genetic algorithm (GA), depth first search (DFS), and branch-and-bound method as a new technique that guarantees the removal of blind spots and subsequently determines the optimal wireless coverage using minimum number of transmitters. The proposed system outperforms the existing techniques in terms of algorithmic complexity and demonstrates that the computation time can be reduced as high as 99% and 75%, respectively, as compared to existing algorithms. Moreover, in terms of experimental analysis, the coverage prediction successfully reaches 99% and, thus, the proposed coverage model effectively guarantees the removal of blind spots.

Consistency Between Convergence of Dynamic Assignment and Stochasticity of Microsimulation: Implication for Number of Runs

2017 ◽  
Vol 2667 (1) ◽  
pp. 88-95
Author(s):  
Neeraj Saxena ◽  
Vinayak V. Dixit ◽  
S. Travis Waller
Keyword(s):  
Network Performance ◽  
Dynamic Network ◽  
Computation Time ◽  
User Equilibrium ◽  
Medium Size ◽  
Modeling Framework ◽  
Network Characteristics ◽  
Dynamic Assignment ◽  
Minimum Number ◽  
Valid Estimate

Dynamic transportation models route vehicles by using the principles of dynamic user equilibrium. These models include a dynamic network loading (DNL) module that is used to evaluate link costs. However, an element of stochasticity creeps into the modeling framework when the analytical dynamic assignment (DA) procedure is used along with a stochastic microscopic DNL. A methodologically correct way of approaching this problem is by solving the entire DA with a microscopic DNL (DA-microDNL) model until convergence for a given random seed and then repeating the process with different seed values. This paper proposes an approach to determine the minimum number of replications of the DA-microDNL model to determine a statistically valid estimate of the measure of effectiveness (MOE). The approach was tested on a small and medium-size network having different demand and network characteristics. Results show that running the integrated DA-microDNL framework for a minimum number of replications provides a statistically significant MOE at much lower computation time. The consistent estimates obtained by using this approach would provide robust information to transportation planners and practitioners in evaluating the impacts of several policy decisions on network performance.

scholarly journals Differential Evolution Algorithm for Multilevel Assignment Problem: A Case Study in Chicken Transportation

2018 ◽  
Vol 23 (4) ◽  
pp. 55 ◽  
Author(s):  
Sasitorn Kaewman ◽  
Tassin Srivarapongse ◽  
Chalermchat Theeraviriya ◽  
Ganokgarn Jirasirilerd
Keyword(s):  
Differential Evolution ◽  
Assignment Problem ◽  
Differential Evolution Algorithm ◽  
Computation Time ◽  
Search Performance ◽  
De Algorithm ◽  
Minimum Number ◽  
Average Computation Time ◽  
Two Stages

This study aims to solve the real-world multistage assignment problem. The proposed problem is composed of two stages of assignment: (1) different types of trucks are assigned to chicken farms to transport young chickens to egg farms, and (2) chicken farms are assigned to egg farms. Assigning different trucks to the egg farms and different egg farms to the chicken farms generates different costs and consumes different resources. The distance and the idle space in the truck have to be minimized, while constraints such as the minimum number of chickens needed for all egg farms and the longest time that chickens can be in the truck remain. This makes the problem a special case of the multistage assignment (S-MSA) problem. A mathematical model representing the problem was developed and solved to optimality using Lingo v.11 optimization software. Lingo v.11 can solve to optimality only small- and medium-sized test instances. To solve large-sized test instances, the differential evolution (DE) algorithm was designed. An excellent decoding method was developed to increase the search performance of DE. The proposed algorithm was tested with three randomly generated datasets (small, medium, and large test instances) and one real case study. Each dataset is composed of 12 problems, therefore we tested with 37 instances, including the case study. The results show that for small- and medium-sized test instances, DE has 0.03% and 0.05% higher cost than Lingo v.11. For large test instances, DE has 3.52% lower cost than Lingo v.11. Lingo v.11 uses an average computation time of 5.8, 103, and 4320 s for small, medium and large test instances, while DE uses 0.86, 1.68, and 8.79 s, which is, at most, 491 times less than Lingo v.11. Therefore, the proposed heuristics are an effective algorithm that can find a good solution while using less computation time.

scholarly journals Analysis of transition cost and model parameters in speaker diarization for meetings

2021 ◽  
Vol 2021 (1) ◽  
Author(s):  
Beatriz Martínez-González ◽  
José M. Pardo ◽  
José A. Vallejo-Pinto ◽  
Rubén San-Segundo ◽  
Javier Ferreiros
Keyword(s):  
Computation Time ◽  
Superior Performance ◽  
Vector System ◽  
Model Parameters ◽  
Speaker Diarization ◽  
Minimum Duration ◽  
Test Set ◽  
Penalty Term ◽  
Dinner Party ◽  
Minimum Number

AbstractThere has been little work in the literature on the speaker diarization of meetings with multiple distance microphones since the publications in 2012 related to the last National Institute of Standards (NIST) Rich Transcription Evaluation Campaign in 2009 (RT09). Lately, the Second DIHARD Challenge Evaluation has also covered diarization at dinner party meetings that include multiple distant microphones. Dinner party meetings are somehow harder than office meetings because their participants can move freely around the room. In this paper, we studied some of the algorithms on speaker diarization for meetings with multiple distant microphones for the NIST Rich Transcription Evaluation Campaign in 2007 (RT07) and RT09 and provide definite and clear improvements. On the one hand, little or no care has been taken to the problem of penalizing or favoring transitions between speakers other than proposing a minimum duration of a speaker turn or calculating the speakers’ probabilities using Variational Bayes (VB). We have studied this issue and determined that a transition penalty term is needed that should be independent both of the number of active speakers and the minimum duration of speaker turns. On the other hand, the determination of a method to automatically select the right number of parameters is crucial in developing good models for speakers. Previous studies have proposed the dynamic selection of the number of parameters based on the duration of the speaker’s speech with a mixed performance when tested at one distant microphone meetings or multiple distant microphones meetings. In this paper, we propose a new method that takes into account both the duration of speaker’s speech to determine a minimum number of parameters, and the question of overfitting issue to determine a maximum number of them, also taking into account the computation time in order to reduce it.We have carried out experiments to support our findings, and we have been able to improve our baseline speaker error rate with multiple distant-microphone meetings. Both methods achieve improved performance over the baseline. The first method obtains a 21.6% decrease in relative speaker error for the development set and a 4.6% decrease in relative speaker error for the test set (RT09). The second method obtains a 46.47% decrease in relative speaker error for the development set and a 17.54% decrease in relative speaker error for the test set. Both methods complement each other, and when they are applied in combination, we obtain a 47.2% decrease in relative speaker error for the development set and a 22.02% decrease in relative speaker error for the test set.The performance obtained with our proposal is outstanding in some subsets of the development test such as the NIST RT07 and among the best for RT09 using our proposed simple modifications. Furthermore, with our algorithm we obtain gains in computation time without jeopardizing performance. Results with a different publicly available database, augmented multiparty interaction (AMI) obtains a 28.44% decrease in relative speaker error confirming the validity of our methods. Preliminary experiments with a single stream (mfcc) endorse the validity of our findings. Comparisons with an x-vector system deliver superior performance of our system on unseen test data.

View-Factor Evaluation by Quadrature over Triangles

1998 ◽  
Vol 12 (1) ◽  
pp. 118-120 ◽  
Author(s):  
C. K. Krishnaprakas
Keyword(s):  
View Factor ◽  
Factor Evaluation

scholarly journals A Fast, Accurate and Easy to Implement Method for Pose Recognition of an Intramedullary Nail using a Tracked C-arm

2014 ◽  
Vol XL-5 ◽  
pp. 217-223 ◽  
Author(s):  
H. Esfandiari ◽  
S. Amiri ◽  
D.D. Lichti ◽  
C. Anglin
Keyword(s):  
Intramedullary Nail ◽  
Accuracy Assessment ◽  
Computation Time ◽  
X Ray ◽  
Main Challenge ◽  
Lower Radiation Dose ◽  
Minimum Number ◽  
Automated Technique ◽  
Orthopaedic Community ◽  
Better Than

A C-arm is a mobile X-ray device that is frequently used during orthopaedic surgeries. It consists of a semi-circular, arc-shaped arm that holds an X-ray transmitter at one end and an X-ray detector at the other. Intramedullary nail (IM nail) fixation is a popular orthopaedic surgery in which a metallic rod is placed into the patient's fractured bone (femur or tibia) and fixed using metal screws. The main challenge of IM-nail fixation surgery is to achieve the X-ray shot in which the distal holes of the IM nail appear as circles (desired view) so that the surgeon can easily insert the screws. Although C-arm X-ray devices are routinely used in IM-nail fixation surgeries, the surgeons or radiation technologists (rad-techs) usually use it in a trial-and-error manner. This method raises both radiation exposure and surgery time. In this study, we have designed and developed an IM-nail distal locking navigation technique that leads to more accurate and faster screw placement with a lower radiation dose and a minimum number of added steps to the operation to make it more accepted within the orthopaedic community. The specific purpose of this study was to develop and validate an automated technique for identifying the current pose of the IM nail relative to the C-arm. An accuracy assessment was performed to test the reliability of the navigation results. Translational accuracy was demonstrated to be better than 1 mm, roll and pitch rotations better than 2° and yaw rotational accuracy better than 2–5° depending on the separate angle. Computation time was less than 3.5 seconds.

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