RSA Variant with Improved Computational Performance and Memory Usage

: Substantial research has been conducted to compare web servers or to compare databases, but very limited research combines the two. Node.js and Golang (Go) are popular platforms for both web and mobile application back-ends, whereas MySQL and Go are among the best open source databases with different characters. Using MySQL and MongoDB as databases, this study aims to compare the performance of Go and Node.js as web applications back-end regarding response time, CPU utilization, and memory usage. To simulate the actual web server workload, the flow of data traffic on the server follows the Poisson distribution. The result shows that the combination of Go and MySQL is superior in CPU utilization and memory usage, while the Node.js and MySQL combination is superior in response time.

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MINLP formulations for continuous piecewise linear function fitting

Computational Optimization and Applications ◽

10.1007/s10589-021-00268-5 ◽

2021 ◽

Author(s):

Noam Goldberg ◽

Steffen Rebennack ◽

Youngdae Kim ◽

Vitaliy Krasko ◽

Sven Leyffer

Keyword(s):

Linear Function ◽

Piecewise Linear ◽

Piecewise Linear Function ◽

Mixed Integer ◽

Function Fitting ◽

Computational Performance ◽

Integer Nonlinear Programming ◽

Minlp Model ◽

Necessary Constraints ◽

Continuous Piecewise Linear Function

AbstractWe consider a nonconvex mixed-integer nonlinear programming (MINLP) model proposed by Goldberg et al. (Comput Optim Appl 58:523–541, 2014. 10.1007/s10589-014-9647-y) for piecewise linear function fitting. We show that this MINLP model is incomplete and can result in a piecewise linear curve that is not the graph of a function, because it misses a set of necessary constraints. We provide two counterexamples to illustrate this effect, and propose three alternative models that correct this behavior. We investigate the theoretical relationship between these models and evaluate their computational performance.

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Detecting Apples in the Wild: Potential for Harvest Quantity Estimation

Sustainability ◽

10.3390/su13148054 ◽

2021 ◽

Vol 13 (14) ◽

pp. 8054

Author(s):

Artur Janowski ◽

Rafał Kaźmierczak ◽

Cezary Kowalczyk ◽

Jakub Szulwic

Keyword(s):

Image Analysis ◽

Pilot Study ◽

Production Management ◽

Satellite System ◽

Morphological Operations ◽

Computational Performance ◽

Analysis Methods ◽

Manual Counting ◽

In The Wild ◽

Global Navigation Satellite

Knowing the exact number of fruits and trees helps farmers to make better decisions in their orchard production management. The current practice of crop estimation practice often involves manual counting of fruits (before harvesting), which is an extremely time-consuming and costly process. Additionally, this is not practicable for large orchards. Thanks to the changes that have taken place in recent years in the field of image analysis methods and computational performance, it is possible to create solutions for automatic fruit counting based on registered digital images. The pilot study aims to confirm the state of knowledge in the use of three methods (You Only Look Once—YOLO, Viola–Jones—a method based on the synergy of morphological operations of digital imagesand Hough transformation) of image recognition for apple detecting and counting. The study compared the results of three image analysis methods that can be used for counting apple fruits. They were validated, and their results allowed the recommendation of a method based on the YOLO algorithm for the proposed solution. It was based on the use of mass accessible devices (smartphones equipped with a camera with the required accuracy of image acquisition and accurate Global Navigation Satellite System (GNSS) positioning) for orchard owners to count growing apples. In our pilot study, three methods of counting apples were tested to create an automatic system for estimating apple yields in orchards. The test orchard is located at the University of Warmia and Mazury in Olsztyn. The tests were carried out on four trees located in different parts of the orchard. For the tests used, the dataset contained 1102 apple images and 3800 background images without fruits.

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Computational Performance of Disparate Lattice Boltzmann Scenarios under Unsteady Thermal Convection Flow and Heat Transfer Simulation

Computation ◽

10.3390/computation9060065 ◽

2021 ◽

Vol 9 (6) ◽

pp. 65

Author(s):

Aditya Dewanto Hartono ◽

Kyuro Sasaki ◽

Yuichi Sugai ◽

Ronald Nguele

Keyword(s):

Heat Transfer ◽

Steady State ◽

Natural Convection ◽

Lattice Boltzmann ◽

Numerical Results ◽

Convection And Heat Transfer ◽

Steady State Condition ◽

Physical Systems ◽

Flow And Heat Transfer ◽

Computational Performance

The present work highlights the capacity of disparate lattice Boltzmann strategies in simulating natural convection and heat transfer phenomena during the unsteady period of the flow. Within the framework of Bhatnagar-Gross-Krook collision operator, diverse lattice Boltzmann schemes emerged from two different embodiments of discrete Boltzmann expression and three distinct forcing models. Subsequently, computational performance of disparate lattice Boltzmann strategies was tested upon two different thermo-hydrodynamics configurations, namely the natural convection in a differentially-heated cavity and the Rayleigh-Bènard convection. For the purposes of exhibition and validation, the steady-state conditions of both physical systems were compared with the established numerical results from the classical computational techniques. Excellent agreements were observed for both thermo-hydrodynamics cases. Numerical results of both physical systems demonstrate the existence of considerable discrepancy in the computational characteristics of different lattice Boltzmann strategies during the unsteady period of the simulation. The corresponding disparity diminished gradually as the simulation proceeded towards a steady-state condition, where the computational profiles became almost equivalent. Variation in the discrete lattice Boltzmann expressions was identified as the primary factor that engenders the prevailed heterogeneity in the computational behaviour. Meanwhile, the contribution of distinct forcing models to the emergence of such diversity was found to be inconsequential. The findings of the present study contribute to the ventures to alleviate contemporary issues regarding proper selection of lattice Boltzmann schemes in modelling fluid flow and heat transfer phenomena.

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New general mixed-integer linear programming model for mobile workforce management

Optimization and Engineering ◽

10.1007/s11081-021-09597-0 ◽

2021 ◽

Author(s):

András Éles ◽

István Heckl ◽

Heriberto Cabezas

Keyword(s):

Programming Model ◽

Time Windows ◽

Mutual Exclusion ◽

Parallel Execution ◽

Mixed Integer ◽

Management Problem ◽

Routing Problem ◽

Workforce Management ◽

Computational Performance ◽

Wide Range

AbstractA mathematical model is introduced to solve a mobile workforce management problem. In such a problem there are a number of tasks to be executed at different locations by various teams. For example, when an electricity utility company has to deal with planned system upgrades and damages caused by storms. The aim is to determine the schedule of the teams in such a way that the overall cost is minimal. The mobile workforce management problem involves scheduling. The following questions should be answered: when to perform a task, how to route vehicles—the vehicle routing problem—and the order the sites should be visited and by which teams. These problems are already complex in themselves. This paper proposes an integrated mathematical programming model formulation, which, by the assignment of its binary variables, can be easily included in heuristic algorithmic frameworks. In the problem specification, a wide range of parameters can be set. This includes absolute and expected time windows for tasks, packing and unpacking in case of team movement, resource utilization, relations between tasks such as precedence, mutual exclusion or parallel execution, and team-dependent travelling and execution times and costs. To make the model able to solve larger problems, an algorithmic framework is also implemented which can be used to find heuristic solutions in acceptable time. This latter solution method can be used as an alternative. Computational performance is examined through a series of test cases in which the most important factors are scaled.

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Semiparametric likelihood inference for heterogeneous survival data under double truncation based on a Poisson birth process

Japanese Journal of Statistics and Data Science ◽

10.1007/s42081-021-00128-w ◽

2021 ◽

Author(s):

Achim Dörre

Keyword(s):

Survival Data ◽

Process Model ◽

Optimization Method ◽

Finite Sample ◽

Birth Process ◽

Dimensional Parameter ◽

Lifetime Distributions ◽

Computational Performance ◽

Semiparametric Likelihood ◽

Double Truncation

AbstractWe study a selective sampling scheme in which survival data are observed during a data collection period if and only if a specific failure event is experienced. Individual units belong to one of a finite number of subpopulations, which may exhibit different survival behaviour, and thus cause heterogeneity. Based on a Poisson process model for individual emergence of population units, we derive a semiparametric likelihood model, in which the birth distribution is modeled nonparametrically and the lifetime distributions parametrically, and define maximum likelihood estimators. We propose a Newton–Raphson-type optimization method to address numerical challenges caused by the high-dimensional parameter space. The finite-sample properties and computational performance of the proposed algorithms are assessed in a simulation study. Personal insolvencies are studied as a special case of double truncation and we fit the semiparametric model to a medium-sized dataset to estimate the mean age at insolvency and the birth distribution of the underlying population.

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Modeling and Simulation Techniques Used in High Strain Rate Projectile Impact

Mathematics ◽

10.3390/math9030274 ◽

2021 ◽

Vol 9 (3) ◽

pp. 274

Author(s):

Derek G. Spear ◽

Anthony N. Palazotto ◽

Ryan A. Kemnitz

Keyword(s):

High Strain Rate ◽

Strain Rate ◽

Smoothed Particle Hydrodynamics ◽

High Strain ◽

Lagrangian Analysis ◽

Computational Performance ◽

Lagrangian Modeling ◽

Analysis Technique ◽

Particle Hydrodynamics ◽

Smoothed Particle

A series of computational models and simulations were conducted for determining the dynamic responses of a solid metal projectile impacting a target under a prescribed high strain rate loading scenario in three-dimensional space. The focus of this study was placed on two different modeling techniques within finite element analysis available in the Abaqus software suite. The first analysis technique relied heavily on more traditional Lagrangian analysis methods utilizing a fixed mesh, while still taking advantage of the finite difference integration present under the explicit analysis approach. A symmetry reduced model using the Lagrangian coordinate system was also developed for comparison in physical and computational performance. The second analysis technique relied on a mixed model that still made use of some Lagrangian modeling, but included smoothed particle hydrodynamics techniques as well, which are mesh free. The inclusion of the smoothed particle hydrodynamics was intended to address some of the known issues in Lagrangian analysis under high displacement and deformation. A comparison of the models was first performed against experimental results as a validation of the models, then the models were compared against each other based on closeness to experimentation and computational performance.

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